Qatar Foundation Annual Research Forum Volume 2012 Issue 1
- تاريخ المؤتمر: 21-23 Oct 2012
- الموقع: Qatar National Convention Center (QNCC), Doha, Qatar
- رقم المجلد: 2012
- المنشور: ٠١ أكتوبر ٢٠١٢
101 - 150 of 469 نتائج
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Early detection and treatment of chronic hepatitis C in a community-based setting in Doha, Qatar: A dynamic preventive model
Background: Detecting early infection of chronic hepatitis C (CHC) can prevent late-stage complications including the need for transplant and death. However, screening hepatitis C virus for early detection of the disease has not been found to be beneficial in average risk individuals according to US Food and Drug Administration guidelines. Objectives: The primary aim of this study was to detect infection with hepatitis C antibodies using a rapid immunochromatographic assay in a community setting. The secondary aims included assessment of prevalence rate, disease characteristics and response to the standard treatment. Methods: A screening survey of 13,704 people (0.9% of the population) was conducted from December 2008 through July 2010. It was carried out in three phases involving 4000, 3212 and 6492 average and high risk people. Hepatitis C antibodies were detected using a colloidal gold enhanced rapid immunochromatographic assay. The diagnosis of CHC was confirmed by measuring the viral load using highly sensitive molecular assays. All patients that were detected as having at least stage 1 disease on the liver biopsy were offered standard treatment with pegylated interferon and ribavirin. The complete cost of investigation and treatment was either state funded or supported through governmental charities. Results: 272 (2%) people were detected to have antibodies against hepatitis C virus. 148 subjects (62%) consented for further confirmation of the disease by molecular assays. 69 subjects (70%) agreed to be treated of which 18 were finally excluded due to detection of minimal disease (stage zero) on the liver biopsy. Overall, 78% of patients were detected as having mild disease (stage 1-2) on histology. Of the 51 actually treated with dual antiviral therapy, 37 (72.4%) responded to the treatment and achieved a sustained viral response (SVR). The response rate was found to be superior to the standard of care at present. The screening strategy resulted in six times better the response rate (odds ratio 6.4, p-value 0.002, 95% CI 2.0-20.5). Conclusion: Hepatitis C was detected in 2% of the population using this novel method. A dynamic model (screening) resulted in detection of mild disease with a consequently higher response rate compared to the standard of care.
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Computational analysis of a mutation in cardiac myosin binding protein-C
المؤلفون: Magdi Yacoub, Poornima Gajendrarao and Navaneeth KrishnamoorthyThe cardiac muscle contraction is regulated by a set of proteins known as sarcomeric proteins, which are components of thick and thin filaments. Mutation in these proteins especially cardiac myosin binding protein-C, a multi-domain (C0-C10) protein, is one of the major causes of hypertrophic cardiomyopathy (HCM). However, structure-function relationship of this protein is unclear. Mutation E258K, which is located in the C-terminal of domain C1, has been shown to be associated with HCM in Egypt. Hence, the purpose of the study was to understand the molecular basis of this missense mutation. Molecular modelling study was performed using the available crystal structure of the domain C1. Here, we have carried out molecular dynamic simulations for both WT and E258K for 10 ns, and the structures that showed major changes were considered for further analyses. Our results suggest that the mutation can change the local structural stability through altering a series of intramolecular interactions. Moreover, as the mutation results in replacement of a negative amino acid by a positive one, thus, it affects the surface electrostatic properties of the domain (Figure). Hence, it might interfere with the binding to neighbouring domains and with the other sarcomeric proteins such as actin and myosin. E258K appears to affect the structural integrity of the domain C1 both directly and indirectly. It is hoped that these findings can help to understand the molecular mechanism of the disease.
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Biochemical and cellular characterization of human atherosclerotic carotid plaque and blood flow: Implications for stroke prevention
المؤلفون: Ahmed Khattab, Leopold Streletz, Dirk Deleu, David Wertheim, Nick Petford, Joseph Kwan, Lasantha Wijesinghe and Steve AllenBackground and Objectives: The Arabian Gulf region is rapidly developing, with major changes in lifestyle that can increase the risk of cardiovascular diseases, including stroke. Stroke constitutes a major cause of morbidity and mortality in Qatar. This research focuses mainly on ischaemic stroke, aiming to study carotid plaque morphology at biochemical, cellular and molecular levels. The objectives are to identify markers that can be measured in surrogate tissues (e.g., blood) in order to identify patients at risk of developing the criteria for clinical intervention to prevent or reduce the risk of stroke. Methods: Fifteen carotid plaques were collected from routine carotid endarterectomy surgery. A range of laboratory techniques were used, including SDS-PAGE, Western blotting, histology, immuno-histochemistry, DD-PCR, flow-modelling, bright-field and laser scanning confocal microscopy (LSCM). Results: Levels of matrix metalloproteinase-3 (MMP-3) and its precursor (pro-MMP-3) were higher in echolucent than in echogenic plaques, especially near regions of ulceration, necrosis and where the fibrous cap was thin or torn. Isoforms of nitric oxide synthase (NOS) were seen in all carotid plaques irrespective of intraplaque features however, levels of inducible NOS (NOS-II) were higher in echolucent than in echogenic plaques. Higher levels of immunoreactive superoxide dismutase were observed in plaques with higher degree of stenosis (>75%-80% measured by ultrasonography). 3D imaging using LSCM showed evidence of carotid plaque vulnerability demonstrated by reduced fibrous cap thickness and a large lipid-necrotic core with evidence of cracking. Five PCR products were identified in echogenic plaques and three PCR products were identified in echolucent plaques which were absent from echogenic plaques. Some of these PCR bands are the products of genes which appear to be up- or down-regulated during plaque development. Blood flow simulation models showed how blood velocity changes could occur associated with reduction in lumen diameter caused by the plaque. Conclusions: Our findings could help in understanding factors affecting plaque morphology. The switching 'off or on' of genes and their encoded proteins may play an important role in stabilisation or destabilisation of carotid plaques. This may lead to digestion of fibrous tissue, leading to thinning or tearing of the fibrous cap and to plaque disruption, initiating embolization and stroke.
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Involvement of renal cytochrome P450 and arachidonic acid metabolites in diabetic nephropathy
المؤلفون: Stephanie Eid, Miran Jaffa, Ayad Jaffa, Fuad Ziyadeh and Assaad EidBackground and Objectives: Diabetic nephropathy (DN), a serious complication of diabetes, is characterized by hyperfiltration, hypertrophy, extracellular matrix accumulation, fibrosis and proteinuria leading to loss of renal function. In renal hypertrophy, tubules increase in size and cause accumulation of the extracellular matrix, and are also associated with alterations in renal sodium handling as well as hypertension; processes linked by involvement of the arachidonic acid (AA) metabolites 20-HETE and EETs. This study aims to determine the specific AA-metabolizing CYP450 isoforms present in proximal tubules (PT) that are altered by high glucose (HG) in cultured PTs, and in an animal model of diabetes. It intends to investigate the effects of alterations in CYP isoforms and/or AA-metabolite levels in DN. This work will investigate the mechanism of PT injury and the effect of inhibition of AA-metabolites in vitro and will also provide insight into the cross-talk between CYP450 isoforms and other sources of reactive oxygen species (ROS). Methods: Immunohistochemistry, hypertrophy, apoptosis, fibrosis, ROS generation, 20-HETE and EET formation, CYP4A and Nox protein expression, and mRNA levels were measured in vitro and in vivo. Results: Exposure of PT cells to HG resulted in apoptosis and hypertrophy. HG treatment increased ROS production and was associated with CYP4A and CYP2C upregulation, 20-HETE and EETs formation, and Nox oxidases upregulation. The effects of HG on Nox proteins and mRNA expression, matrix protein accumulation and apoptosis were blocked by HET0016, an inhibitor of CYP4A, and were mimicked by 20-HETE. Inhibition of EETs in vitro promoted the effects of HG on cultured proximal tubular cells. In parallel, the levels of CYPs 2B, 2C, and 4A were assessed in a rat model of streptozotocin-induced diabetes. There was significant induction of expression and activity over control of these CYPs associated with an increase in ROS production, Noxs expression, PTs injury, and this was prevented by insulin therapy. Conclusion: Our results indicate that hyperglycemia in diabetes has a significant effect on the expression of AA-metabolizing CYPs, manifested by increased AA metabolism, and might thus alter kidney function through alteration of type and amount of AA metabolites; this pathway is through an oxidative stress-dependant mechanism.
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Ubiquitous monitoring system for critical cardiac abnormalities
المؤلفون: Uvais Qidwai, Junaid Chaudhry and Mohammed ShakirIt is desirable to have a monitoring system that can keep a constant surveillance on the conditions of the heart and its related patterns. This is particularly important in many patients with critical cardiac abnormalities. This can be very convenient in clinical settings but may not be possible for individuals who are not in hospital and are in their day-to-day activities. Wearable ECG-based systems have been proposed for such situations and can perform such monitoring in real life. However, detecting the abnormality in near real-time is still a challenge in these systems. Similarly, what information should be relayed to doctors or other caregivers and how soon this can be achieved is a very hot area of research at present. This work presents a monitoring system that embeds an intelligent wearable data acquisition system with unique identification algorithms requiring very little computational time and simple threshold based classification. Once this is done, the related information is passed to a gateway system that can communicate the criticality flags as well as the actual ECG waveform data to the pre-defined data node that connects it to the doctor and/or other clinical representatives. We have used an Android-based cellphone as the gateway. The presented system focuses on intelligent health monitoring with possible wearable application for long-term monitoring and updating in real-time of patient's ECG conditions to the physician.
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TNRC9 (TOX3) downregulates BRCA1 expression and promotes breast cancer aggressiveness
Background: Although the linkage between germline mutations of BRCA1 and hereditary breast/ovarian cancers is well established, recent evidence suggests that altered expression of wild type BRCA1 might contribute to the sporadic forms of breast cancer. The mechanism underlying the downregulation BRCA1 expression is not well understood. It might be dependent upon repressor activity that governs histone acetylation and DNA accessibility at the BRCA1 promoter. TNRC9 (TOX3) gene, highly associated with breast cancer susceptibility, encodes a nuclear protein of uncertain function but can modify chromatin structure. We hypothesized that constitutive expression of TNRC9 could be relevant to breast cancer biology through the modulation of BRCA1 activity. Methods: We assessed the associations of TNRC9 gene amplification with breast cancer onset and survival. The search for targets and effects of TNRC9 was performed using multifaceted molecular approaches. Results: The TNRC9 gene is often amplified and overexpressed in breast cancer, particularly in advanced breast cancer. TNRC9 gene amplification is associated with reduced disease-free and metastasis-free survival rates. TNRC9 significantly increased breast cancer cell proliferation, migration and survival of exposure to apoptotic stimuli, and tumor progression both in vitro and in mice models. Gene expression profiling, protein analysis and in silico assays of large datasets of breast and ovarian cancer samples suggested that TNRC9 and BRCA1 expression are inversely correlated. TNRC9 binds not only to BRCA1 promoter but also to the CREB complex, a BRCA1-transcriptional regulator. TNRC9 downregulates the expression of BRCA1 by altering the methylation status of its promoter. Conclusions: Our study unveils a molecular basis for a TNRC9 role in breast cancer and highlights a new paradigm in BRCA1 regulation.
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Screening for novel natural and synthetic inhibitors for human α-amylases and their structure determination: An effective approach to control diabetes mellitus and obesity
Background: Non-insulin-dependent diabetes mellitus (NIDDM) is one of the most common adult diseases caused by a secretory decrease in insulin from pancreatic Langerhans cells and/or peripheral cells which become resistant to the action of insulin as in the case of obesity. Serious side effects such as retinopathy, neuropathy, and cataracts are also brought about by its long-term manifestation. At present, the direct clinical therapy in NIDDM is to optimize or control the postprandial blood glucose (PBG) level. Polysaccharide degrading enzyme, such as α-amylase catalyzes the cleavage of starch to produce glucose and other smaller polysaccharides which leads to an increase of the glucose level in the blood. Thus, the retardation of the action of this enzyme by suitable inhibitors may be one of the most effective approaches to control NIDDM. Objectives: The aim of this work was to screen, isolate and determine the structure of novel inhibitors for human polysaccharide degrading enzymes, salivary and pancreatic α-amylases, using natural resources and synthetic compounds. Methods: We prepared the total extracts of several herbs and plants collected from different locations in Egypt and in Qatar randomly and based on traditional use. Each extract was assayed for potential amylase inhibitors. The potential inhibitors were isolated using silica gel chromatography. The structure of each inhibitor was determined using elemental analysis, IR, 1H-NMR, MS and 13C-NMR. Hundreds of synthetic compounds have also been tested for inhibition capabilities. Results: Our study demonstrated that the total extract of four plants showed a significant inhibition of human saliva and pancreatic α-amylases. The active compounds from two plants were isolated and their structures determined. Three synthetic compounds with a significant but variable degree of inhibition of human saliva α-amylase and pancreatic amylase were identified. Conclusion: The novel inhibitors isolated in this study could form the basis for clinical trials to demonstrate the effectiveness of these compounds in lowering the glucose level in NIDDM patients and obese people.
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Akt-activated endothelium constitute the niche for residual disease and resistance to bevacizumab in ovarian cancer
Background: Ovarian cancer is the second leading cause of cancer-related death in women worldwide. Despite optimal cytoreduction and adequate adjuvant therapy, many patients will experience disease recurrence. Targeted therapies have been evaluated in ovarian cancer as a method to overcome resistant disease. Antiangiogenic therapy such as bevacizumab (Avastin; Genentech) has limited efficacy. Indeed, it increases hypoxia, drug resistance and, tumor rebound phenomenon observed after withdrawal. Hypothesis: We hypothesized that abnormalities in the tumor endothelium contribute to tumor growth which may be a direct source for chemotactic factors and might be responsible for residual microscopic disease and rebound effect following antiangiogenic treatment. Methods: Using a feeder-free Matrigel and spheroid models of ovarian cancer, we examined the effect of bevacizumab on residual disease. We used Akt-activated endothelial cells (EC) that replicates tumor endothelial biology and controls tumor growth, and human umbilical vein endothelial cells (HUVEC) to investigate the antiangiogenic activity of bevacizumab by angiogenesis and migration assays. We conducted an XTT assay to examine the effect of bevacizumab on proliferation of vascular endothelial growth factor (VEGF) producing human ovarian cancer cell lines. Finally, expression of FGF-2, phospho-Akt was assessed by Western blotting and flow cytometry. Results: We demonstrated the role of Akt-activated ECs in supporting expansion and self-renewal of ovarian cancer cells (OCC) in a residual disease context. We demonstrated that OCCs activate the endothelium, which displays resistance to bevacizumab. Bevacizumab had no effect on the proliferation of Akt-activated ECs, but significantly inhibited angiogenesis and delayed wound healing in HUVEC. We demonstrated that in this setting the cross-talk between cancer cells and ECs activates Pi3k/Akt inducing an autocrine loop through the pro-angiogenic factor fibroblast growth factor-2 (FGF-2) bypassing the VEGF-R pathway. We demonstrated that FGF-2 blocking would efficiently reverse the resistance to bevacizumab. Conclusion: Our data highlights the role of an activated endothelium in the constitution of the residual disease and resistance to bevacizumab. These results hint on the concept of using combination therapy to override drug resistance in ovarian cancer and to suppress or eradicate residual disease.
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Trends in the mortality and short-term morbidity outcomes of ≤32 week gestation babies in the State of Qatar between 2002 and 2011: A PEARL study analysis
المؤلفون: Sajjad ur Rahman, Najeeb Hameed, Hussain Parappil, Nuha Nimeri, Sarrah El Tinay, Walid El Ansari and Mohammad TahirBackground and Objectives: Preterm births are a major cause of neonatal mortality and morbidity. The number of preterm births is increasing due to assisted reproductive technology. The intensive care of preterm babies and follow-up care of their post-discharge morbidities takes up a major share of healthcare expenditure. PEARL study analyzed trends in mortality and pre-discharge morbidity outcomes of ≤32 week gestation preterm babies in the State of Qatar between 2002 and 2011. Methods: The 2011 data of ≤32 week babies, collected prospectively using predesigned, structured questionnaires by a trained fulltime research team, was ascertained from Qatar's National Perinatal Registry (Q-Peri-Reg). Comparative data for 2002 was ascertained retrospectively from the medical records of the Women's Hospital, Hamad Medical Corporation. The data was analyzed for outcome measures. The 2011 data was also compared with 2010 report of Vermont Oxford Network (VON) database, which is an international benchmark of quality of care in NICU's worldwide. Results: Between 2002 and 2011 the birth rate of ≤32 week babies increased significantly from 1.19% to 1.75% (p=0001) while their mortality decreased significantly (p <0.05) from 239/1000 to 163.4/1000 respectively. There was a significant decrease in the RR of Grade 3 IVH (p <0.012) and a non-significant decrease (p=0.500) in Grade 4 IVH and CLD at 36 weeks. There was a significant increase in the RR of symptomatic PDA (p=0.018), NEC (p=0.003) and ROP stage 3 and above (p=0.001) and non-significant increase in the RR of cystic PVL (p=0.470) (Table 1). Qatar's ≤32 weeks mortality and some morbidity outcomes were comparable with VON 2010 database report. Conclusions: The mortality and select short-term morbidity outcomes of ≤32 week gestation babies have improved significantly over the last decade though their birth rate has increased. There is a need to focus on further reduction in morbidity.
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Mutations in a zinc finger protein causing a novel autosomal recessive mental retardation syndrome identified through homozygosity mapping and whole exome sequencing of a single affected individual
المؤلفون: Marios Kambouris, Tawfeg Ben-Omran, Yasser Al-Sarraj, Rehab Ali, Khaoula Erraffi, Wesal Habbab and Hatem El-ShantiA consanguineous Arab family affected by a novel autosomal recessive disorder characterized by severe mental retardation and failure to thrive, was studied by Illumina 700K SNP genotyping, candidate gene mutation screening and whole exome sequencing for one affected member. Clinical findings include ptosis, bilateral epicanthic folds, striking midface hypoplasia, downturned mouth corners, thin upper vermillion, prominent ears, bilaterally short fourth metatarsal bone, bilateral fifth finger camptodactyly, mildly limited mobility in both knees and hypotonia. The gene was mapped by homozygosity mapping to 4 possible genome intervals, as the number of family members was insufficient for a significant LOD score. The positional candidate MAP2K1 was sequenced. No pathogenic mutations were identified. Whole exome target enrichment sequencing was performed on ABI SOLiD 4 System and Illumina HiSeq platforms for a single affected individual. Six non-synonymous variants were positioned within the homozygosity intervals. Two affecting evolutionary highly conserved amino acids with damaging effects according to PolyPhen and SIFT protein-modeling software, which were validated by Sanger sequencing to determine whether variants co-segregated with the disease phenotype. The variants were absent in 188 ethnically matched control chromosomes. One gene shows very limited expression in the brain while the other, a zinc finger protein, appears to be the disease causing mutation. Zinc finger proteins, a family of DNA and RNA binding proteins are transcriptional regulators controlling developmental cascades of gene expression especially during fetal brain development. Mutations in zinc finger domains interfere with normal brain development, are associated with non-syndromic X-linked mental retardation with impairments in adaptive behavior, and manifest during the developmental period causing severe mental retardation. The c.C5054G [p.S1685W] mutation affects 2 of the 3 ZNF407 isoforms, is located in the last third of the zinc finger domains and affects a serine residue in the alpha-helical part adjoining two zinc finger domains. This is thought to eliminate the functionality of downstream domains and interferes with expression of various genes under ZNF407 control during fetal brain development. Homozygosity mapping and whole exome sequencing of a single affected individual was the most effective, least labor intensive and most economical approach in identifying the mutation for this novel autosomal recessive zinc finger protein that causes a mental retardation syndrome.
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In vivo assessment of reactive oxygen species in the brain using novel dihydroethidium-based methodology
المؤلفون: Amro Wagih Wafi, Heinrich Lob and Robin DavissonReactive oxygen species (ROS), e.g. superoxide, hydrogen peroxide, peroxynitrite, are important mediators for many cell signaling processes. In the central nervous system, cardiovascular function is tightly regulated by cell signaling in specific nuclei (the subfornical organ (SFO), paraventricular nucleus (PVN), and rostral venterolateral medulla (RVLM)) and an imbalance of ROS in these nuclei contributes to the development cardiovascular diseases, e.g. hypertension. There are limitations to quantify and localize ROS in brain tissue. The current state-of-the-art method to measure ROS in the brain is in situ quantification of dihydroethidium (DHE) fluorescence using confocal microscopy. DHE is a cell permeable compound, which upon reaction with ROS forms red fluorescent 2-hydroxyethidium. However, in situ DHE imaging has a number of technical problems. Recent developments with in vivo DHE methods may circumvent these problems but, this methodology has not been well established for brain, particularly cardioregulatory nuclei. The aim of this study was to test whether in vivo DHE methodology using either systemic or direct brain administration of DHE, may be an alternative to in situ DHE. Mice were injected with lipopolysaccharide (LPS) (8 micrograms/g i.p.) to elicit ROS production in the brain. In control groups we injected saline or LPS and tempol (200 microliters of 10 mM tempol, i.p.), which is a ROS scavenger. Three hours later mice were injected with DHE (150 microliters of 150 micrograms/mouse, i.p.) and brains were harvested one hour later. In a second experiment we administered DHE via an intracerebroventricular (ICV, 1 microliter of 10 micromolar DHE) cannula (including the same controls), which allows direct delivery of DHE to the brain. Our results show that LPS caused increased DHE fluorescence intensity in the SFO, RVLM and PVN but not in control areas e.g. the cortex when DHE was administrated intraperitoneally. Saline- and tempol-treated mice showed much lower DHE fluorescence. The distribution pattern was similar in both experiments. In conclusion, this study shows that DHE administered either systemically or directly into the brain leads to effective detection of LPS-induced ROS formation in brain centers important in cardiovascular homeostasis and may be an important alternative to in situ DHE.
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The incidence of of polycystic ovary syndrome among reproductive females in the state of Qatar: A cross-sectional study
المؤلفون: Yumna Zia, Sumaya Rahman, Elham Sharif and Nasser RizkBackground & Objectives: Stein-Leventhal syndrome commonly known as polycystic ovary syndrome (PCOS) is the most common endocrinopathy among reproductive females. PCOS is a multisystem challenge causing not only gynecological issues such as irregular menstrual cycles, hyperandrogenism and infertility but also causing insulin resistance, type 2 diabetes and cardiovascular diseases. The objective of our study was to determine the incidence of PCOS among reproductive females at Qatar University using the National Institutes of Health (NIH), the Rotterdam consensus (Rott.) and the Androgen Excess Society (AES) criteria to determine the common phenotypes and hormonal parameters found in Qatar. Our aim was also to conduct a community-based study to make up for the lack of work done in female healthcare. Methods: A sample size of 121 females between the ages of 18-25 years were evaluated for symptoms of PCOS using family history of PCOS, body mass index and hormonal analysis. The sample was divided into the following four groups: control (n= 49), irregular menstrual cycles only (n= 13) , hyperandrogenism only (n= 27) and PCOS group (n= 31). Blood was drawn for measurement of TSH, progesterone, insulin, estradiol, SHBG, testosterone, DHEAS and prolactin. Modified Ferriman-Gallwey score was used for the evaluation of hirsutism. Results: The incidence of PCOS was found to be 25.83% (n= 31) using the Rotterdam criteria. Lower values were achieved using AES (20.83%, n= 25) and NIH (19.17%, n =23) definitions. Among our PCOS group, 16.13% (n= 5) were Qataris, 48.39% (n= 15) were Asians, 22.58% (n= 7) were Africans and 12.90% (n= 4) Europeans. Among the clinical features, family history of PCOS (p=0.037), hirsutism (p= 0) and irregular menstrual cycles (p= 0) were found to be significant factors in the PCOS group. Biochemical analysis showed elevated testosterone, elevated DHEAS and decreased SHBG hormones to be significant factors found in the PCOS group. Insulin and prolactin did not show any significant differences between the groups. Four individuals from the PCOS group were aware of their condition while 87% were unaware of their condition. Conclusions: Our study revealed a fairly significant prevalence of PCOS in the region and indicated a lack of awareness among people about their condition. There is need for government initiatives towards adequate investigations, management and treatment of PCOS.
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In silico design of selective high affinity ligands to block CD81-Plasmodium falciparum sporozoites interaction
المؤلفون: Reem Rafik Al Olaby, Ali Sultan, Rod Balhorn and Hassan ME AzzazyBackground and Objectives: Around one million deaths result from malaria each year worldwide. The infection starts by the inoculation of sporozoites by female Anopheles mosquito into the host. The mechanism of invasion of sporozoites into the host is not clear to date. CD81 is considered the only host receptor to be significant for the invasion of sporozoites. The aim of the first phase of this project is to identify potential ligands that binds with high affinity to the residues in CD81 involved in CD81-malaria sporozoites interaction in silico, use them to generate selective high affinity ligands (SHALs) and use these SHALs to inhibit the interaction of CD81-sporozoites, thus preventing progression of malaria infection. Methods and Results: AutoDockTools 1.5.6 was used to prepare the crystal structures of the CD81-LEL protein (1G8Q) by deleting water molecules, adding polar hydrogens, and assigning Gasteiger charges and to create a grid bounding box, which provided the desired grid parameter file using 0.375 A spacing. Autoligand, an AutoDock tool, was used to identify several binding sites on CD81. Fill points were created using a 1 A grid, and the calculations were performed using 10 to 210 fill points. AutoDock 4.2 was used to screen 30,000 ligands obtained from different libraries (NCI_DSII and Asinex) to identify small molecules that might bind to each site. The docking results were analyzed and virtual screening hits for each binding site on CD81-LEL were ranked according to selection criteria required for the design of promising SHALs. Distances between pairs of bound ligands were estimated and used to design several SHALs that should bind selectively to CD81. Conclusion: New computational tools have been used to design in silico several SHAL-based inhibitors that have the potential to prevent entry of Plasmodium falciparum sporozoites into hepatocytes and thus malaria infection.
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High prevalence of the ApoE Arg145Cys dyslipidemia at-risk polymorphism in African-derived populations
Background: Apolipoprotein E (ApoE), a protein component of blood lipid particles, plays an important role in lipid transport and delivery. Single polymorphisms in residues 112 and 158 define the common E2, E3 and E4 alleles. In a study of Qataris, we observed that 17.4% of the African-derived genetic subgroup were heterozygotes for the rare Arg145Cys (R145C) variant that functions as a dominant trait with incomplete penetrance associated with dyslipidemia. Based on this, we hypothesized that the R145C polymorphism may be common in African-derived populations. Methods: The prevalence of the R145C variant worldwide was assessed in the 1000 Genomes Project (1000G) and then in 1012 Caucasians and 1226 African-Americans in New York City. Lipid profiles of the Qatari and New York R145C+ heterozygotes were compared to controls. Results: R145C+ Qatari heterozygotes had higher triglyceride levels compared to Qatari controls (p <0.007). The 1000Gs data demonstrated that the R145C polymorphism is rare in non-African derived populations, but present in 4.9-12.3% of Sub-Saharan African-derived populations. The R145C polymorphism was rare in New York City Caucasians (1/1012, 0.1%), but strikingly, 53 (4.3%) of 1226 New York City African-Americans were R145C+ heterozygotes, with an average of 52% higher fasting triglyceride levels compared to African-American R145C- controls (p <0.002). Conclusions: Based on these observations, there are likely to be millions worldwide derived from Sub-Saharan Africans that are ApoE R145C+. While larger epidemiological studies will be necessary to determine the long-term consequences of this polymorphism, the available evidence suggests it is a common cause of a mild triglyceride dyslipidemia.
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Laparoscopy in pediatric emergencies
المؤلفون: Tariq O Abbas, Ahmed Hayati and Mansour AliAims: Although laparoscopy is rapidly becoming the procedure of choice in adults, there are obstacles to its use in children. We analyzed our institution's experiences with laparoscopic procedures performed in children over the last 5 years, with particular emphasis on emergency procedures. Methods: We retrospectively evaluated the records of patients less than 14 years of age who had undergone laparoscopy for non-trauma related emergency conditions between January 2006 and December 2010 in our institution. Clinical parameters evaluated included operation time, total length of hospital stay, and postoperative complications. Results: Over the study period, children less than 14 years old underwent 482 laparoscopic procedures, 300 on an emergency basis and 182 electively. The majority of procedures were laparoscopic appendectomies, with most of the others being resections of ovarian cysts, Meckel's diverticula, or adhesiolyses. We observed improvement in outcomes over the 5-year period, as shown by decreased operation times and shorter postoperative hospital stays. Moreover, the numbers of laparoscopically performed procedures increased over time. Conclusion: Laparoscopy provides excellent results, including better exposure and cosmetic outcomes, when used for emergency operations in children. In our institution, the numbers and types of laparoscopic procedures have increased over time, and their outcomes have improved.
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Stroke prevention therapy in elderly patients hospitalized with atrial fibrillation: A 20-year experience from Qatar
Objectives: Stroke prevention therapy with oral anticoagulants (OAC) is reported to be under-utilized in patients with atrial fibrillation (AF) despite the overwhelming evidence supporting their use for stroke prevention. Rates and trends of the use of OAC from the developing world in this setting are lacking particularly in elderly patients. The aim of this study is to evaluate trends of utilization of OAC in elderly patients hospitalized with AF in a real-world population in a Middle-Eastern country over 20 years. Methods: Retrospective analysis of prospective registry of all patients aged above 70 years hospitalized with AF in Qatar from 1991 through 2010 was made. Rate and trends of OAC use was examined over the 20 years of the study. Results: During the 20-years period; 744 patients above the age of 70 years old were hospitalized for AF. Overall 26.1% of these patients received OAC with warfarin at hospital discharge while 60.2% received anti-platelets therapy with aspirin. The use of warfarin in this elderly group was significantly trending higher over the study period from 3.7% in the earlier years of the study to 39.5% in the latter years (P= 0.001). Anti-platelets therapy with aspirin also significantly increased from 47.4% in the earlier years of the study to 67.3% in the latter years (P= 0.001) [Table]. Conclusions: Although our study demonstrates that stroke prevention therapy with OAC and anti-platelets therapy are used with increasing frequency in elderly patients aged above 70 years over the 20-year study period, nonetheless they remain under-utilized. Further prospective studies are needed to investigate the reasons behind under-utilization of OAC in our region to help guide healthcare providers involved in the care of elderly people with AF to maximize potential benefit from OAC and anti-platelets while minimizing the hemorrhagic risk associated with these drugs.
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Identification of a novel mutation in a glycosylation type I defect gene causing a unique phenotype by homozygosity mapping and whole exome sequencing of an affected individual
المؤلفون: Yasser Al-Sarraj, Mohammed Tolefat, Hatem El-Shanti and Marios KambourisA consanguineous Qatari family affected by a novel autosomal recessive disorder characterized by severe mental retardation, retinal degeneration, optic nerve atrophy, ataxic gait and edematous puffiness of hands was studied by genome-wide SNP genotyping with Illumina 200K SNP-chips, candidate gene mutation screening and whole exome sequencing for one affected member. Homozygosity mapping indicated a 19.6 MB segment in the long arm of chromosome 4 from 55.8-56.0 Mb. LOD score is calculated for the region of homozygosity to establish linkage. This interval contains more than 100 genes, none of which has been implicated in any of the relevant phenotype. Candidate genes within the region of homozygosity were prioritized by examination of their physiologic roles and possibility of producing the disease phenotype. Screening 30 positional candidate genes showed no pathogenic mutations. Whole exome target enrichment sequencing was performed on ABI SOLiD4 for a single-affected individual. Three non-synonymous variants were positioned within the homozygosity intervals. At the same time a report appeared in the literature describing an Iranian family with very similar clinical characteristics with a defect in the Steroid 5 alpha-Reductase 3 [SRD5A3] gene. This gene localizes within the homozygosity interval and it showed one novel missense variation c.T744G/p.F248L on whole exome sequencing in our Qatari family. The mutation was validated by Sanger sequencing, it co-segregates with the disease phenotype and is not present in the 1000 genome database. The mutation is predicted to be damaging by Polyphen and SIFT protein-modeling software and it is absent in 162 ethnically matched control chromosomes. The protein encoded by this gene is a 318 amino acid enzyme that belongs to the steroid 5-alpha reductase family, and polyprenol reductase subfamily. This protein is necessary for the conversion of polyprenol into dolichol, which is required for the synthesis of dolichol-linked monosaccharides and the oligosaccharide precursor used for N-linked glycosylation of proteins. Mutations in this gene are associated with congenital disorder of glycosylation type I. Biochemical testing reconfirmed a glycosylation defect in the affected individuals. This family presents a unique phenotype in the spectrum of glycosylation defect related disorders.
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Quantitative serum proteomics facilitates diabetes biomarker discovery and validation in a Qatari population
المؤلفون: Prabhjit Kaur, Nasser Rizk, Noura Younes, Mahmoud Zirie and Amrita K CheemaBackground: The incidence and prevalence of type 2 diabetes mellitus (T2DM) is on the rise in Qatar. The pathogenesis of T2DM is complex owing to molecular heterogeneity in the afflicted population. Current diagnostic methods rely on blood glucose measurements, which are non-informative with respect to progression of the disease to other associated pathologies. Thus predicting the risk and development of T2DM-related complications like cardiovascular disease remains a major challenge. Methods: We have used a combination of quantitative methods for characterization of circulating serum biomarkers of T2DM using a cohort of non-diabetic control subjects (n=76) and patients diagnosed with T2DM (n=106). In this case-control study, the samples were randomly divided as training and validation data sets. In the first step iTRAQ (isobaric tagging for relative and absolute quantification) based protein expression profiling was performed for identification of proteins displaying a significant differential expression in the two study groups. Five of these protein markers were selected for validation using multiple reaction-monitoring mass spectrometry (MRM-MS) and further confirmed with Western Blot and QRTPCR analysis. Results: We report the identification and verification of several biomarker candidates that can be potentially used for subset stratification of T2DM cohort. We identified a total of 227 high confidence proteins corresponding to 1393 peptides with greater than 95% confidence representing >40% sequence coverage. GO analysis predicted the differentially expressed proteins to be involved in a wide variety of cellular and metabolic processes. A total of 124 proteins showed a fold change of 2 or more between the control and T2DM serum samples. We report a set of five proteins viz. apolipoprotein-A-1, vitamin D binding protein, fibronectin, afamin and transthyretin as potent biomarkers, which are significantly up-regulated in diabetics. Conclusion: Our study revealed that many distinct molecular networks and metabolic pathways were activated in T2DM. It is hoped that future studies with larger cohorts as well those that focus on dissecting mechanistic roles will enhance our understanding of pathogenesis of T2DM and contribute to the development of targeted therapeutics in accordance with the personalized medicine paradigm.
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Hyperinsulinaemia and hyperleptinaemia are BMI independent features of morbid obesity in a Qatari, compared to a Caucasian, population: Effect of surgical weight loss.
Background: Recent trends suggest that the sharpest increases in the prevalence of obesity are in countries of the Middle East, especially in Qatar. Early and rapid onset of the disease in this population, along with a primarily abdominal omental deposition of adipose tissue, is closely associated with insulin resistance, whilst longer duration of obesity in Caucasians is associated with maintenance of insulin sensitivity, independently of BMI. The impact of more aggressive treatments for obesity, such as surgery, on the metabolic health of the Qataris is not known. Objectives: To test the hypothesis that inherent differences between the Qataris and Caucasians in adipose tissue secretory function and sensitivity to insulin determines their response to interventions that reduce their adipose tissue mass. Methods: Non-diabetic morbidly obese subjects were recruited from Qatari and Caucasian patients awaiting weight reduction surgery (Al-Emadi Hospital, Doha, Qatar and Whittington Hospital, London, UK). Anthropometric measures were recorded. Blood samples were obtained before, and in a sub-set after weight loss for determination of lipids, glucose, insulin and adipokines. Insulin resistance was measured by HOMA. Results: The Qataris were significantly younger (p=0.005), despite having comparable BMI (Qatari 47.7±7.0; Caucasian 48.4±7.6 kg/m-2, p=0.70). They also had lower diastolic blood pressure and a better lipid profile. However, the Qataris had significantly higher insulin and HOMA index of insulin resistance, and higher leptin and interleukin-6. Also, in Qataris, leptin was negatively correlated with a number of risk factors for metabolic syndrome, independent of BMI. However, these correlations seem to be BMI-dependent in Caucasians. Further, weight loss in Caucasians did not significantly change insulin sensitivity but did reduce dyslipidemia. While in Qataris, characterized by high insulin resistance, weight loss causes sharp reduction in insulin resistance but not in dyslipidemia. Conclusion: Obesity in Qatari subjects was accompanied by a higher degree of hyperinsulinaemia and hyperleptinaemia compared to Caucasians. The nature of obesity and high insulin resistance in Qataris makes it amenable to aggressive weight loss treatment, whereas in Caucasians other less aggressive treatments for obesity may be applicable.
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MicroRNA-181a* targets nanog in a subpopulation of CD34+ cells isolated from peripheral blood
المؤلفون: Mohamed Emara, Paul Mintz, Pal Sætrom, Vikash Reebye, Marie B Lundbæk, Joanna P Nicholls, Nagy A Habib and Abdelali HaoudiBackground and Objectives: Hematopoietic stem cells (HSC) are the most widely studied and characterized adult stem cells, which play an essential role in sustaining the formation of blood and immune system. The ease of their manipulation, the lack of serious ethical issues, and, in the autologous setting, the absence of their immunogenicity, have made them an attractive tool for developing stem cell-based therapies. Exploiting the properties of HSC by microRNA (miRNA) profiling offers an attractive approach to identify new regulators of stem cell fate. Although numerous miRNA have been screened from hematopoietic stem cells (HSC), the targets corresponding to many of these miRNA have not yet been fully elucidated. Therefore the objective of this study is to generate a miRNA profile from a subpopulation of adherent CD34+ HSC isolated from G- colony-stimulating factor mobilized peripheral blood aiming to understand the role of selected miRNA in regulating HSC stemness. Methods: CD34+ cells from patients' blood were isolated using a CD34+ isolation kit (Miltenyi Biotec) according to the manufacturer's protocol. miRNA profiling of adherent and nonadherent CD34+ cells was done using TaqMan Array MicroRNA Cards. Nanog expression levels was tested using a dual-luciferase reporter construct for miR-181a* or its mutant variant and Nanog 3′ UTR mRNA. Results: In this study, we have identified eight clusters of miRNA that were differentially expressed in an adherent subpopulation of CD34+ stem cells. Further analysis of one of the clusters by bioinformatics revealed that a miRNA, miR-181a*, which is highly expressed in the adherent CD34+ cells, affects the expression levels of Nanog, a stem cell surrogate marker. We show specifically by reporter assay and mutational analysis that miR-181a* targets a seedless 3′ compensatory site in the 3′UTR of Nanog and affects gene expression. We demonstrate that inhibiting miR-181a* upregulates the Nanog expression level, in addition to an increase in alkaline phosphatase activity. Conclusions: In conclusion, our results highlight a new stem cell-related target for the miR-181 family and show that miR-181a* directly targets Nanog in a subpopulation of CD34+ stem cells suggesting a possible role of miR-181a* in regulation of adherent CD34+ HSC cells stemness.
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Depot-specific differences in vascular noradrenergic sensitivity in morbidly obese Qataris
Background & Objectives: Expanding adipose tissue in obesity requires effective vasoreactivity to combat hypoxia and its consequences, such as insulin resistance and type 2 diabetes. While recent evidence suggests that the adipose tissue is highly angiogenic, the tissue arteriolar vasoreactivity has been less investigated. Furthermore, the omental adipose tissue (OAT) synthesizes greater levels of vasocontrictive molecules, such as cytokines and catecholamines, compared to the sub-cutaneous (SAT) depot and these are likely to impact the maintenance of vascular tone leading to greater susceptibility to hypoxia. The aim of the study was to investigate differences in the contractile responses of adipose tissue arterioles between the SAT and OAT depots in an insulin-resistance prone, morbidly obese Qatari population. Methods: SAT and OAT from obese non-diabetic Qatari patients (age 29, BMI 43, HOMA 2.69), undergoing weight reducing surgery were used to investigate tissue noradrenaline (NA)-mediated vasoconstriction by wire myography. Vessels were cut into segments (~2 mm) and mounted on a dual wire myograph (510A) for measurement of isometric tension. Cumulative concentration-response curves were then constructed for noradrenaline (10-9 -10-5 M). Curves were also constructed for potassium Chloride (KCl, 1-70 mM). Results: Arterioles from SAT showed greater sensitivity to NA compared to OAT (log EC50 -6.9±0.1 vs -6.1±0.2 p<0.05). The SAT curve was clearly shifted to the left of OAT although the maximum tensions for both were not statistically different. For KCl, maximum tension was greater in the SAT than in the OAT vessels but there were no differences in their sensitivities. Conclusions: OAT arterioles from morbidly obese Qataris were less sensitive to noradrenaline mediated vasoconstriction compared to SAT vessels; however, the contractile responses of the two depots to KCl were comparable. Therefore differences in adrenoceptor density/function may underlie the depot specific responses. The consequences of these differences between the arterioles are currently under investigation.
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Challenges of reliability testing in Qatar: Patient willingness for participation by mail or in person in a novel research instrument in Doha, Qatar.
المؤلفون: Amal Khidir, Maha Elnashar, Huda Abdelrahim, Maya Hammoud, Humna Asad and Michael FettersBackground: Novel survey instrument development requires reliability testing, but limited information informs the preferred approach in Qatar. The testing of survey characteristics of the Multi-Cultural Assessment Inventory-Qatar (MAI-Q), a novel multicultural assessment tool in Arabic, English, Hindi and Urdu, provided the opportunity to investigate survey distribution procedures. Objective: To determine willingness to participate, and response rates during survey reliability testing by mail and in person. Methodology: To examine participation preferences and rates, patients were recruited through HMC and six primary health centers. When recruited, subjects could choose to take the MAI-Q a second time for the reliability testing in person or by mail. Subjects were either scheduled for follow-up in-person, or were sent the survey in a prepaid, preaddressed envelope. Results: Among 387 subjects who initially took the survey, 177 (46%) declined taking the survey a second time for reliability testing. Of 210 subjects who agreed to take the survey a second time for reliability testing, 145/210 (69%) chose mail, and 65/210 (31%) were offered and chose in person follow-up. Actual follow-up to complete reliability testing was only 29/145 (21%) by post but 40/65 (63%) in person. Conclusion: These findings reveal challenges researchers face when developing and distributing surveys in Qatar. Nearly half of subjects initially recruited were not willing to participate in follow-up testing. Among those agreeing to follow-up testing, the majority chose mail, but only a fifth of them returned instruments. The majority of subjects who chose in person follow up completed testing. These data inform researchers about the tough choices for developing and conducting surveys in Qatar.
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Clinical Research activity in Qatar and the WHO Eastern Mediterranean region: A quantitative analysis.
المؤلفون: Raghib Ali and Abdul Bari BenerBackground and Objectives: Clinical research has led to some of the most important advances in improving human health including the discovery of important risk factors for heart disease, diabetes and cancer as well as treatments for common diseases which have led to unprecedented increases in life expectancy. Unfortunately despite having nearly 600 million people, the Eastern Mediterranean region (EMR) is one of the most underdeveloped parts of the world in terms of clinical research (3.1 clinical studies per million people versus a global average of 19 per million.) However, this overall figure masks important differences between the 22 countries of the EMR and our objective was to quantify clinical research activity in Qatar and other countries of the EMR. Methods: We used data from clinicaltrials.gov (a registry of publicly and privately supported clinical studies of human participants) which lists all clinical research studies being conducted in every country. We quantified clinical research activity by dividing the number of studies in each country by its population to get the metric number of clinical studies per million people. Results: Qatar had the second highest clinical research activity in the EMR at 18 studies / million people. There was a very wide variation in the number of studies ranging from 36 / million people (Lebanon) to 0 studies / million people (Somalia) with the average across the region being 3.1. Full results are shown in Table 1. Conclusion: Qatar's level of clinical research activity was far above the average for the region and almost reaches the global average. This is a remarkable achievement considering that clinical research only began in Qatar a few years ago. Given Qatar's commitment to, and funding for, clinical research it is likely that Qatar will become the regional leader in clinical research in the near future.
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Design of new high resolution quadratic time-frequency distributions for monitoring newborn health outcomes
المؤلفون: Taoufik Ben Jabeur and Boualem BoashashBackground: In order to monitor the health of new borns , high performance sensors are placed on the body to record information from different organs: nervous system (EEG signals), heartbeat and fetal movement (accelerometer signals). As the received data are non-stationary signals, Quadratic Time-frequency distributions (QTFDs) are often used to represent the energy, temporal and spectral characteristics of these signals. The suitable QTFD should conserve a high resolution and removes the cross-terms artifacts given by inner- and outer- terms. The inner-terms artifacts are observed in mono-component signals. Due to the Quadratic form of the QTFD, outer-terms are added to inner-terms if the signal contains more than one component. Recent QTFDs such as Wigner-Ville distribution, Spectrogram, B distribution, Modified B-Distribution, Choi-Williams, focus on the elimination of outer-terms whereas few works dealt with the inner-terms artifacts. Objectives: This work aims at designing a new kernel that takes into account the presence of both inner-terms and outer-terms artifacts. The proposed QTFD should remove these artifacts while maintaining a high resolution. Methods: A theoretical analysis of the localization of the inner-terms is given. Based on this analysis, we propose first a new kernel that removes the inner-terms for mono-component signal. Multicomponent signals are also considered, in which case we extend the proposed kernel in order to take into account the presence of the outer-terms. Results and conclusion: The resulting TFDs are compared with other methods using several examples of mono-component and multi-component signals. Some real data representing EEG signals and fetal movement are also used. The different simulations indicate that the proposed TFDs are more efficient to the existing ones, leading to potential significant improvement in newborn health outcomes. This work is supported by Qatar National Research Fund, NPRP project No 09-626-2-243
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Liver image segmentation from CT data
المؤلفون: Sarada Prasad Dakua and Julien Abi-NahedBackground & Objectives Despite its long track record, segmentation in medical image computing still remains an active field of research, largely due to the complexities of in-vivo anatomical structures. We present a novel segmentation algorithm based on chaotic theory; the preliminary results show the potential of the technique. Methods: Henri Poincare first developed (later revisited by Lorentz) this chaotic model by observing a significant deviation in output through his "three-body-system" when the input is varied even slightly. This theory can be applied to image segmentation ensuring deterministic convergence by keeping initial conditions constant. The scenario is analogous to "iron particles moving randomly in a cell and a strong magnet is suddenly placed on its center". Though the process is chaotic, now it becomes periodic and is easy to solve. The probability of a particle to reach the magnet can be found by solving the magnetostatic version of Laplacian equation. The image is treated as a graph; a seed point is placed both on foreground and background individually and the node potentials are calculated in each case. The label map is built by considering the maximum of two probabilities at a node. Finally, gradient operation on the label map determines the coordinates that carry nonzero value as the desired contour coordinates. Results: The qualitative results shown in Fig. 1 reflect the method accuracy when compared to the ground-truth data. The liver CT datasets are collected from MICCAI 2007 workshop. For a single image, it takes nearly 3 sec to complete the operation on a system with 2GB RAM core2duo processor. Conclusions: This paper has presented a fast and simple graph-based segmentation algorithm based on chaotic theory which is deterministic and time efficient. In future, we intend to explore its behavior on different subjects and modalities as well.
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The development of a set of shared core IPE competencies and evaluation criteria for Qatar: The process and the product
المؤلفون: Brad JohnsonInterprofessional Education (IPE) is defined by the World Health Organization (WHO) as the process by which a group of practicing health-care professionals work together in order to provide promotive, preventive, curative, rehabilitative and other health-related services. WHO strongly encourages efforts to develop and integrate IPE into educational health-care programs for patients' benefits. For this to occur, a set of shared core competencies must be developed and used as a base on which to build and strengthen interprofessional skills in health-care professionals. Little or no research has been made to develop a set of IPE shared core competencies in Qatar. This article describes the method and results of the competency specification process developed by our team. At a first stage, a list of domains with their descriptions were developed using a card-sorting approach. A pyramid model with IPE at the top was also developed. The second stage was to develop the list of shared core competencies related to the domains developed above. The method used was a Delphi-based approach. One of the necessary steps was to draft candidate competencies based on 8 local experts and review of relevant literature. Based on this, feedback from local experts was integrated in an iterative process. The list of competencies was reduced from 20 statements approximately per domain to an average of 6 statements per domain. A rubric was also developed which can be used to evaluate students on the dimensions outlined in the shared core competencies.
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Does religious fasting in the Islamic holy month of Ramadan predispose to atrial fibrillation? A population-based study
المؤلفون: Amar M Salam, Hajar A AlBinali, Abdul Wahid Al-Mulla, Rajvir Singh and Jassim Al SuwaidiBackground and Objectives: Over one billion Muslims religiously fast worldwide during the month of Ramadan. Fasting during Ramadan is essentially a radical change in lifestyle for the period of one lunar month, so it is important to see whether this change predisposes patients to developing atrial fibrillation (AF). Our objective in this study is to investigate whether Ramadan fasting has any effect on the number of hospitalizations with AF in a geographically defined Islamic population. Methods: We conducted a retrospective review of clinical data study on all Qatari patients in Qatar for a period of 20 years (January 1991 through December 2010) who were hospitalized with AF. Patients were divided according to the time of presentation in relation to the month of Ramadan; 1 month before, during and 1 month after Ramadan. The number of hospitalizations for AF in various time periods was analyzed. The age of presentation, gender, cardiovascular risk factor profiles and outcome were analyzed. Results: Of the 41,453 patients treated during the 20-year period, 14,814 of them were Qataris, 8758 being males and 6056 females. Overall, 1718 Qatari patients were hospitalized for AF and their mean age and standard deviation was 61±16 years, 47.3% were hypertensive, 7.5% were current smokers and 39.2% were diabetics. The overall mortality was 5.9%. The number of hospitalizations for AF was not significantly different in Ramadan (143 cases) when compared to a month before Ramadan (136 cases) and a month after Ramadan (151 cases); p = 0.95. There was no significant difference found in the baseline clinical characteristics, presentation, or mortality in patients presenting in various time periods (p = non-significant for all) [Table]. Conclusions: This population-based study demonstrates for the first time no significant difference in the number of hospitalizations for AF and related morbidity and mortality while fasting in Ramadan when compared to the non-fasting months. We therefore conclude that religious Ramadan fasting does not predispose to the development of AF.
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Assessment of ultrasonic-assisted enzymatic digestion of complex protein mixtures by high-resolution mass spectrometry
المؤلفون: Shaima S Dib, Anja M Billing, Shareef J Antar and Johannes GraumannBackground & Objectives Large-scale proteome analysis by mass spectrometry is commonly preceded by enzymatic digestion of proteins. The conventional protocol for in-solution digest of complex protein mixtures includes trypsin and is performed at room temperature for at least 12h. To improve this time-consuming method we assessed the efficiency of focused ultrasound-assisted enzymatic digest. It has previously been shown that ultrasonication can dramatically reduce digestion time. However, it is not known how this affects protein identification and quantification when applied to complex protein mixtures such as whole cell lysates. Here, we explore in-depth the proteome of embryonic stem cells comparing trypsin-digestion methods with and without ultrasound support side-by-side. Methods In-solution protein digest Protein extracts were digested with sequencing-grade trypsin (Promega) for 1, 5, 10, 20, 30, 40min and 1h in the presence or absence of focused ultrasonication (Covaris). A conventional digestion overnight was included. Reactions were stopped by acidification and heat. Peptides were desalted by reverse phase C18 StageTips. Mass spectrometry Peptides were analyzed on a QExactive (Thermo Scientific) coupled to Easy nLC 1000 (Proxeon). Raw files were processed by MaxQuant v1.3.0.3 software. Peptide searches were performed by Andromeda search engine against the UniProt database. Results and Conclusions Focused ultrasonication clearly enhanced the enzymatic digestion and can be implemented in the daily workflow of mass spectrometry-based proteome analysis.
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Uropathogens from Qatari type 2 diabetics with asymptomatic bacteriuria: Antibiotic sensitivity, virulence factors and phylogenetic groups of isolated Escherichia coli
المؤلفون: Nahla Afifi, Asma Al-Thani, Soliman Ewis, Asmaa Abu Abdullah, Haneen Albardawil, Heba Yasin and Wazeera RoubanThe urinary tract infections (UTIs) are among the most common bacterial infections in diabetic patients, especially asymptomatic bacteriuria. The aim of this study is to investigate the causative organisms of ABU in type 2 diabetic patients, the phylogenetic grouping and the antibiotic sensitivity pattern of the causative organism in order to determine the drug of choice to cure ASB in diabetics. One hundred & sixty eight men were recruited from attendants of the out-patients clinics at the Army Force Medical Unit in Qatar and were divided into two groups; Group 1 (130 type 2 diabetics) and Group 2 (38 non-diabetic subjects). We found that 20% of diabetic patients had ASB and Escherichia coli was the most prevalent pathogen (92.31%). Genotypic study showed that the most prevalent E. coli groups responsible for UTI belonged to group A and B2 (33.3% for each group). Moreover , Nitrofurantoin was the most sensitive antibiotic for the groups B2, B1 ,D (100%) and 75% for group A. Phenotypic study by SEM showed that there is variation in the diameter. The B1 group had the largest width and length (L= 2.391 ± 0.483)(W=622.667 ± 51.215) while group D was the shortest (L=1.876 ± 0.247) and group A had the lowest width (W=580.21 ± 44.93). Further comparison of virulence factors with symptomatic diabetics is required to determine why ASB lacked symptoms in spite of the presence of virulent genes.
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Viral etiology of acute gastroenteritis among hospitalized patients in Doha, Qatar: A pilot study
المؤلفون: Asma Althani, Maide Mustafa Yuksel, Said Aldahry and Najah Mohamed Al LawatiIntroduction: Acute gastroenteritis is a widespread disease that is characterized by diarrhea, vomiting and abdominal pain. It has high morbidity and mortality rate globally. Bacteria, parasites and mostly viruses cause acute gastroenteritis. Most frequent viruses are norovirus, adenovirus, astrovirus and rotavirus. Objectives: To determine the prevalence of the four viruses in the stool samples of patients who were treated at HGH with complaints of acute gastroenteritis. The samples which had been submitted to the microbiology laboratory at HGH, were analyzed by real time-PCR method at Qatar University. The second objective was to compare between ELISA, IMCG and RT-PCR in terms of sensitivity and specificity. Methodology: 288 stool samples and corresponding patients' data were obtained from microbiology laboratory in HMC between 15-Jun-2009 to1-Nov-2009. They were transported to the research lab of biomedical science program- Health Department at Qatar University, where laboratory experiments involving RT-PCR were performed. Statistical analysis was carried out using Excel program. Results: Out of total 288 fecal samples, 131 (45.5%) were positive for the presence of viruses that cause gastroenteritis. Norovirus (28.5%) was the most prevalent, followed by rotavirus (10.4%), adenovirus (6.25%) and astrovirus (0.30%). Conclusion: Norovirus is the most common source of acute gastroenteritis among hospitalized patients, followed by rotavirus. Real time-PCR technique used in this study was found to be more sensitive and specific. By taking RT-PCR as a reference, ELISA and IMCG are found to be similarly low in sensitivity and specificity.
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Phenylephrine induced Na+/H+ exchanger isoform 1 expression modulates cell viability in human embryonic kidney (HEK 293) cells.
المؤلفون: Iman Abdelaziz, Taqdees Mahroof and Fatima MraicheBackground: Na+/H+-exchanger isoform 1 (NHE1) is a ubiquitously expressed housekeeping glycoprotein that functions to regulate intracellular pH. Current reports have suggested that NHE1 is crucial to cell survival in the context of chronic kidney disease. The cellular mechanism by which NHE1 stimulates cell survival requires further investigation. Osteopontin (OPN), is a macrophage chemotactic protein that has been linked to tissue injury in non‐diabetic kidney disease. Whether expression of NHE1 counteracts the role of osteopontin in human embryonic kidney (HEK 293) cells remains to be elucidated. Objective: To establish whether upregulation of NHE1 expression counteracts the negative effects of osteopontin expression in HEK 293. Results: Our results did not reveal protein expression of NHE1 or OPN in HEK 293 under basal conditions. However, the HEK 293 cells overexpressed both NHE1 and OPN following 24-hour stimulation with PE (10uM). The expression of both NHE1 and OPN did not significantly alter the cell viability of the HEK 293 cells. This was verified using trypan blue. Conclusion: NHE1 activation in HEK 293 cells acts as a defense mechanism against apoptotic stress.
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Automated feature detection on ECG waveforms
المؤلفون: Abdul Jaleel Palliyali, Reza Tafreshi, Nasreen Mohsin and Leyla TafreshiThis work presents the development of an algorithm for analyzing ECG waveforms. The identification of the various waveforms on an ECG is the first and most crucial step in any automated analysis. The algorithm developed is capable of detecting all important waveforms. These include the Q,R,S,R' and S' waves, J and ST points and onset and offset of P and T waves. The various techniques utilized in their detection include adaptive thresholding, parabolic curve fitting, modified derivatives and temporal coherence. After detecting the waveforms, various measurements are obtained from the points detected. These include the polarity of the waveforms, the ST elevation, morphology of ST segment, QRS width and T wave morphologies. These measurements can easily be utilized for diagnosing the ECG for various abnormalities. The developed detection and measurement algorithm stands out from previous works in a number of ways. It is comprehensive and capable of detecting all the important ECG waveforms. It works well even on atypical ECG beats with secondary R' and S' waves. The adaptive thresholding approach minimizes the dependence on fixed hard thresholds. The synchronous behavior of ECG recordings across leads is exploited to improve accuracy. The performance of the algorithm was validated on 40 sample 12-lead ECG data of two minutes each. To validate performance on abnormal ECG waveforms, 20 datasets from patients diagnosed for myocardial infarction (MI) were included. An overall detection accuracy of 98.5% was obtained.
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Primary coronary intervention for myocardial infarction in Qatar: First nationwide program
We have designed the first nationwide primary percutaneous coronary intervention (PPCI) program for ST elevation myocardial infarction (STEMI) in Qatar. Guidelines emphasize the door to balloon time (DBT) which should not exceed 90 minutes. This interval reflects the efficiency of the hospital system in the rapid recognition and transfer of the STEMI patient to the catheterization laboratory for PPCI. Although DBT is clearly important and is in the forefront of planning for the wide PPCI program, it is not the only important time interval. Myocardial necrosis begins before the patient arrives to the hospital and even before first medical contact, so time is of the essence. Therefore, our primary PCI program includes a nationwide awareness program for the population and for health care professionals to reduce the pre-hospital delay. We have also taken steps to improve the pre-hospital diagnosis of STEMI. In addition to equipping all ambulances to perform 12-lead ECGs we will establish advanced wireless transmission of the ECG to our heart center and to the smart phone of the consultant on-call for the PPCI service. This will ensure that the patient is transferred directly to the cath lab without unnecessary delay in the emergency rooms. A single phone-call system allows the first medic making the diagnosis to activate the PPCI team. The emergency medical system is acquiring capability to track the exact position of each ambulance using GPS technology to give an accurate estimate of the time needed to arrive to the patient or to the hospital. We also plan for medical helicopter evacuation from far or inaccessible areas. A comprehensive research database is being established to enable specific pioneering research projects and clinical trials, either as a single center or in collaboration with other regional or international centers. The PPCI program is a collaborative effort between the HMC and the QCRC. Qatar will be the first country in the world to have a unified nationwide PPCI program. This program is a model that may be adopted regionally and in developing countries to improve outcomes of patients with STEMI.
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Think small: The zebrafish as a novel disease model in QCRC
المؤلفون: Magdi Yacoub, Thomas Brand and Jan SchlueterAnimal models are essential to understand the molecular and cellular basis of human pathologies. The zebrafish has gained significant attention as a novel model system and has several advantages over rodent models, including: (1) genetic and physiological similarity to humans, (2) a high fertility rate, (3) external fertilization, (4) ease of genetic manipulation, (5) enlarging library of heart-specific reporter genes, (6) ability to survive with a dysfunctional heart, (7) transparency enabling powerful imaging modalities. The zebrafish heart has only two chambers but beats with a heart rate comparable to humans. Several genetic models have been engineered, which successfully model cardiac conditions. Random integration of reporter genes by transposon-mediated transgenesis generated a large number of zebrafish lines, specifically labeling different cardiac cell types and tissues. These include marker genes that label the myocardium, epicardium, endocardium, the conduction system, and atrioventricular and aortic valves (see Figure). Such reporter lines are useful to monitor specific cardiac cell populations and to study their role in disease processes. Similar efforts have recently been employed to identify the cell population responsible for cardiac regeneration. Gene mutations identified in humans causing cardiomyopathies have been introduced in zebrafish and successfully modeled the disease process in this species. Moreover, chemical genetic approaches have been successfully employed to identify small molecules, which are able to reverse pathological conditions such as hypertrophic cardiomyopathy. These examples demonstrate the power and versatility of this model organism, which will pave the way for novel therapeutic opportunities to treat cardiovascular disease. In the Qatar Cardiovascular Research Center we plan to utilize the zebrafish model to study the genetic basis of aortic valve disease, hypertrophic cardiomyopathy, and heart failure. A zebrafish lab will be established in Doha as part of the network in order to develop local expertise and to contribute to the overall research efforts.
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Late stimulation of myocardial recovery, following insertion of a continuous flow LVAD
المؤلفون: Magdi Yacoub, Sherif Helmy, Mohamed Al Hashemi, Cesare Terracciano, Michael Ibrahim, Robert Bonow and Amr BadrThe use of mechanical assist devices for the treatment of advanced heart failure has increased dramatically in recent years. Significant recovery of myocardial function following insertion of left ventricular assisted device (LVAD) occurs in a small percentage of patients due to unloading alone. Several strategies for enhancing the degree of recovery using combination therapy have been introduced. Most of these strategies depend on early use of pharmacologic agents to stimulate reverse remodelling followed by inducing physiologic hypertrophy. We here report the use of the funny current inhibitor ivabradine late after insertion of Heart Mate II in Doha. This was performed following experimental studies in a small animal model which showed the drug induces reverse re-modelling when used in combination with unloading by abdominal heart transplantation. Sequential studies were performed using non-invasive myocardial function and exercise testing after reducing the pump speed to 6,000 RPM, which in effect stops forward flow through the pump. This was performed under full heparinisation. These tests have shown progressive recovery of function following the institution of the combination therapy. Further studies using LVAD's as a platform for recovery are being investigated at QCRC. These studies include formal exercise program and gene and cell therapy. In addition, an extensive basic science program to investigate the mechanisms of recovery is in progress.
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Investigation of genes that are related to colorectal cancer and liver metastasis
المؤلفون: Hassan Adawn, Rania Georges and Martin R. BergerProgression of colorectal cancer (CRC) culminates in liver metastasis. To identify genes that are involved in the metastatic phenotype, cDNA microarrays were used to analyze mRNA expression profiles of CC531 rat colon adenocarcinoma cells for changes related to their homing into the liver. Briefly, CC531 cells were intraportally implanted into the liver of Wag-Rij rats and re-isolated after 3, 6, 9, 14 and 21 days. Altogether 2919 genes from ca. 25000 genes were deregulated as a response to metastasis formation into the liver. Candidates from promising gene families were chosen for further analysis using different in vitro models and human CRC samples. These gene families included the claudins and the insulin-like growth factor binding proteins (IGFBPs). For claudins, it was shown that the initial phase of rat CRC cell homing into the liver involves a transient down-regulation of several claudins. Also it was shown that siRNA silencing of Cldn1 and Cldn4 increased migration and reduced colony formation, with these phenotypes being consistent with metastatic homing. Correspondingly, human CRC samples showed increased Cldn1 and Cldn4 expression in UICC stages l-lll, and significantly reduced expression in stage IV and in liver metastasis. Additionally, the IHC analysis revealed that the expression of Cldn1, Cldn4 and Cldn3 in liver metastasis specimens was lower than in the corresponding primary carcinomas. Taken together, metastasizing cells require a transient reduction in claudin expression for liberation from the primary tumor and then initialization metastatic growth in the liver. For IGFBPs it was shown that deregulation of IGFBP3 and IGFBP7 is related to the metastatic behavior of CRC cells. In CRC patients, a significant correlation between the expression levels of these genes was noticed but no relation to overall survival was registered. Further, the patients' age was inversely correlated with the expression of IGFBP3. Silencing of IGFBP3 and/or IGFBP7 in human and rat colorectal cancer cell lines reduced proliferation, colony formation, and for IGFBP3, also migration. These results indicate that IGFBP3 and 7 cannot be simply assigned to the group of tumor suppressors, but have additional properties, which become evident only in the context of cancer progression and metastasis formation.
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Spatio-temporal characterization of the blood flow in the aortic root
المؤلفون: Magdi Yacoub and Ryo ToriiBackground: The flow profile in the aortic root constitutes a major determinant of coronary and systemic blood flow, depending on the size, shape and dynamism of the aortic root. The aims of this study are to evaluate patterns of flow in the aortic root in health, disease and following different root replacement procedures. Methods: A total of 54 subjects underwent phase-contrast cardiovascular magnetic resonance (PC-CMR). Of those, 29 patients with well functioning aortic valve substitutes had undergone aortic root replacement > 10 years earlier. They were divided into 3 groups: autografts (n = 13, 47±9 years), stentless porcine xenografts (n = 10, 77±8 years) and homografts (n = 6, 71±11 years). The remaining patients had bicuspid aortic valve (BAV, n = 4, 32±17 years) and obstructive hypertrophic cardiomyopathy (HCM, n = 6, 43±9 years). A cohort of 15 healthy volunteers (31±5 years) served as controls to determine normal spatio-temopral flow patterns. Results: The aortic root flow profiles showed differential patterns: (1) BAV patients had a high velocity jet through the narrow valve orifice; (2) HCM patients had eccentric flow patterns due to the obstruction in the left ventricular outflow tract; (3) flow through the autograft valve was triangular in shape reflecting ideal orifice shape of a triliaflet valve, similar to normal controls and (4) flow patterns through the xenografts and homografts are more disrupted than autografts. The maximum velocities for BAV, HCM, autograft, xenograft, homograft and control groups, respectively, were: 2.6±1.8 m/s, 1.6±0.2 m/s, 1.2±0.2 m/s, 2.1±0.9 m/s, 1.7±0.4 m/s, 1.0±0.3 m/s. Conclusions: Flow profiles in the aortic root vary markedly according to the type of disease and root substitute. Among the tissue root substitute options, the Ross procedure best reproduces normal flow dynamics.
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Examining secular trends in the utilization of warfarin among Middle Eastern Arab and South Asian patients hospitalized with atrial fibrillation: 20-year experience from Qatar (1991-2010)
المؤلفون: Amar M Salam, Hajar A AlBinali, Abdul Wahid Al-Mulla, Rajvir Singh and Jassim Al SuwaidiObjectives: There is paucity of data relevant to anticoagulation rates and trends of treatment in patients with atrial fibrillation (AF) in developing countries and whether there are ethnic differences in the utilization of warfarin as some reports have suggested. The aim of this study is to evaluate trends of utilization of warfarin in Arab and South Asian patients hospitalized with AF in a real-world population in a Middle Eastern country. Methods: Retrospective analysis of prospective registry of all patients hospitalized with AF in Qatar from 1991 through 2010 was made. Rate and trends of warfarin use was examined in relation to ethnicity over the years of the study. Results: During the 20 year period; 2857 Arabs and 548 Asians were hospitalized for AF. The mean age of Arabs was 58 years and of Asians 49 years. Overall, 31.8% of Arabs and 39.4% of Asians received warfarin at hospital discharge (p= 0.001). The overall use of warfarin was significantly trending higher from 17 % in the earlier years of the study to 44.1% in the latter years but no differences were found between Arabs and Asians throughout the study period except at the latter years of the study when it was significantly higher in Asians (53% Asians vs. 41.7% Arabs; p= 0.009). Conclusions: Although the trend is significantly increasing over time, warfarin remains underutilized in patients hospitalized with AF irrespective of ethnicity. There is an urgent need for prospective studies to investigate warfarin contraindications, relative warfarin efficacy and bleeding risks in our region to help guide healthcare providers prescribing warfarin and consequently reduce the risk of AF-related disabling strokes.
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An echocardiographic screening of school children for rheumatic heart disease in Aswan, Egypt
المؤلفون: Magdi Yacoub and Susie KotitIntroduction: The global burden of rheumatic heart disease continues to be extremely high, with the main brunt being borne by developing countries. However, the prevalence and disease characteristics vary widely in different populations. Egypt hosts 80 million individuals and is known to be endemic for rheumatic heart disease. Methods: Cross sectional screening of a cohort of randomly selected 3062 school children between the ages of 5 and 15 years in Aswan, a "neglected "part of Egypt. The schools were stratified by area and age group and randomly selected using computer generated random-number. After ethical approval, the children underwent detailed physical and transthoracic echocardiographic examination. A set of rigid criteria including structural and functional changes in left sided valves, were used to determine the presence, distribution and severity of rheumatic affection. The disease was categorized into definite and possible. Findings: The mean age of the children examined was 10 (2*6) years with slight male preponderance (58.7%) which was representative of the whole school population. None of the children were on penicillin prophylaxis or were known to have cardiac disease. Definite and probable rheumatic valve affection was present in 23 and 13*4 per thousand respectively. Mitral valve affection (mainly regurgitation )was present in 96%, aortic regurgitation in 2.9% and combination of both in 1.4%. Left ventricular function was normal in all patients. Auscultation revealed a murmur in 7.1% of children with echocardiographic evidence of rheumatic heart disease showing a 14 fold increased detection rate by echocardiography. Interpretation: Asymptomatic rheumatic heart disease is common in school children in Aswan. The disease affects predominantly the mitral valve producing regurgitation in the majority, These findings are important for instituting early secondary prevention and stimulating future development of specific biomarkers and vaccine development.
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Characterization of wall biomechanics of the pulmonary autograft after the Ross procedure
المؤلفون: Magdi Yacoub, Ryo Torii and Michael IbrahimBackground: There is continuing concern about the risk of long-term autograft dilatation and rupture following the Ross procedure. The aim of this study is to characterize the neo-aortic valve in terms of morphology and wall distensibility. Methods: Among 108 Ross patients undergoing yearly echocardiographic assessment in our unit, 17 (16%) had aortic root diameters of >45mm (DG) 14 ± 1 years after operation. In an attempt to characterize the autograft morphology and dynamics, 11 patients (age 47 ± 10) with dilated autografts underwent cardiac multi-slice computed tomography (CT). Dimensions and distensibility of the aortic root were derived from the cine-CT images. Morphological observation was also made with rapid prototyping models based on the multi-slice CT. The patients were compared with 11 age-matched normal controls (C, age 47 ± 9). Results: Sinus diameters (Ds) were increased in DG compared to C (50 ± 3 mm vs 31 ± 4 mm, p < 0.01). The non-coronary sinus of the autograft tended to enlarge to a greater extent than other two sinuses. Aortic diameters (Da) were also increased in DG (35 ± 6 mm vs 28 ± 3 mm, p < 0.01). DG patients had similar cyclic strain (7.2 ± 3.8% vs 8.3 ± 3.6%, p = 0.13) and distensibility (25 ± 14 vs 34 ± 14 MPa-1, p = 0.20). Conclusions: These data support the notion that the autograft root has similar physical properties to the normal aortic root despite significant dilation. This may have implications for both the selection of aortic root substitutes and the clinical management of Ross patients presenting with dilated roots.
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Molecular modeling of mutations of the human cardiac troponin T hotspot codon 102 associated with hypertrophic cardiomyopathy in Egypt
المؤلفون: Magdi Yacoub, Navaneeth Krishnamoorthy and Poornima GajendraraoHypertrophic cardiomyopathy is the most common inherited heart diseases associated with a large number of mutations in several sarcomere proteins that regulate striated muscle contraction. The 3-dimensional structural and biophysical consequences of these mutations and their impact on the genotype-phenotype relationship remains poorly understood. Mutations in cardiac TroponinT (cTnT) have been reported to purport an increased risk of sudden cardiac deaths. Mutational hotspots such as codon 102 (Arg92 Moolman et al., 1997) of cTnT have been observed in several populations, including recently by our group in Egypt. In an attempt to explain this observation, we have performed molecular modelling of specific key mutations at codon 102, Arg102. The X-ray structure of the core domain of human cardiac troponin complex (cTnC, cTnI and cTnT) has been used for this study after constructing the missing regions. The resultant structure and the mutants were subjected to structural rigidity analysis and mutational modelling. In addition, molecular dynamics simulations were performed to understand the binding of functionally important calcium ions with the troponin complex. Our results suggest that the location of Arg102 in cTnT is instrumental to create a molecular bridge through hydrogen bonds (Figure) between secondary structural elements, in order to hold the core structure together. The loss of this molecular bridge by the key mutations (such as Arg102Leu) could produce conformational changes and affect natural binding of calcium ions, which are essential for regulation of muscle functions. This mechanism can explain the important structural consequences of mutations in this codon, associated with frequent progression of LV dysfunction, as well as the occurrence of ventricular arrhythmias secondary to the intracellular consequences of profound energetic and Ca++ handling derangement.
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Designer scaffolds for tissue engineering heart valves
المؤلفون: Magdi Yacoub, Navaneeth Krishnamoorthy and Jerome SohierCollagen fibers are essential components of tissues and an important protein in the extracellular matrix, which maintains the structural and mechanical integrity of tissues while providing key signals to regulate cell functions. Although animal-based collagens can be used as biomaterial for tissue engineering heart valves, they cause infections and lack flexibility. These limitations have stimulated the exploration of collagen mimetic peptides (CMPs) through a bottom-up approach using computational modeling followed by experiments. Here, a 3D-structure of 3-helices of CMP was used to model the new CMPs to identify its structural stability and hotspots. These data assist in introducing charged residues by mutations to cross-link 3-helices and to add binding motif (GFOGER) for integrin in the CMP structures. The helical stability and self-association of the mutated CMPs have been validated using molecular dynamics (MD) simulations, surface electrostatic calculation followed by biochemical experiments using HPLC and mass spectrometry. The modelling analyses indicated that the CMPs show the desired structural properties for self-assembly and high affinity towards integrin binding. The introduction of the charged residues increased the possibilities for helical cross-link (gelation). The results suggest that altering the positions and length of hydrophobic repeats (GPO) of CMPs could improve thermal stability (Figure). The structural properties of the modelled CMPs were reproduced in experimental conditions. Our study provides potential peptide candidates that promise to show some inherent structural properties of native collagen in silico and in vitro. These properties are required to produce functional scaffolds for tissue engineering heart valves.
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Towards understanding molecular mechanisms of calficic aortic stenosis (CAS)
المؤلفون: Magdi Yacoub, Najma Latif and Adrian ChesterRecent studies have demonstrated that CAS is an active, regulated disease process akin to atherosclerosis, in which resident cells undergo remodeling and transformation. Normal valves harbor a low percentage of smooth muscle cells (SMCs) however their role in CAS is not defined. We analyzed 12 normal and 22 calcified valves for early and late differentiated SMC markers by immunocytochemistry. Expression of myocardin and myocardin-related transcription factors (MRTFA/B) was analyzed. TGFβ1 was used to activate MRTFs in valve interstitial cells and transmission electron microscopy (TEM) was used to detect the presence of SMCs in areas of calcification. The expression of SMC markers calponin, SM1, SM2 and SM22 was increased in all 22 calcified valves with caldesmon, SMC myosin, SMC α-actin and desmin increased in 40-91% of calcified valves. SMC markers were abundantly and aberrantly expressed in surface and microvessel endothelial cells and vasculature in 40% of the calcified valves. Normal valves showed expression of myocardin, MRTF-A and -B in the base of the ventricularis, similar to the pattern of SMC in normal valves. An aberrant expression of myocardin, MRTF-A and MRTF-B, was found in 71%, 53% and 67%, respectively, of calcified valves, in a similar pattern to the aberrant expression of SMC markers. In calcified valves the expression of MRTFs was nuclear in both valve interstitial cells and endothelial cells suggestive of activation. Nuclear expression of MRTF-A was increased by 11-fold in VICs treated with TGFβ1 (10ng/ml) (p<0.05). TEM of the fibrosa layer of calcified valves showed bundles of SMCs and SMC-derived foam cells. In conclusion, SMCs are are aberrantly expressed around calcified nodules and in endothelial cells in CAS with myocardin and MRTFs, key regulators of SMC expression, abundantly expressed. These findings strongly suggest that the SMC phenotype plays an important role in the pathophysiology of CAS.
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Biphasic nanofibrillar matrices for valve tissue engineering
المؤلفون: Magdi Yacoub, Adrian Chester and Jerome SohierOur strategy for heart valve tissue engineering uses autologous cells to populate appropriate template matrices.The goal is to create a suitable scaffold supporting proper cell growth while reproducing the specific mechanical properties of native heart valves extracellular matrix (ECM). Accordingly, aligned and non-aligned nanofibrillar structures of different porosities were prepared and evaluated with regards to their mechanical properties and their ability to support human adipose derived stem cell (hADSC) colonization and growth. Nanofibrillar structures were obtained by jet-spraying poly (ε-caprolactone) dissolved in chloroform at different concentrations (0.0733, 0.0833 and 0.1033 mg/ml). Morphological evaluations of the structures were performed using scanning electron microscopy and porosity calculated. hADSCs (600,000) were top and rotary seeded on nanofibrillar discs (diameter 1 cm and thickness 0.8 mm) and cultured in 10 ml of complete medium under rotation (10 rpm) for 20 days. Histology (DAPI staining) and DNA quantification characterized the resulting cellularized structures. Jet-spraying polymers resulted in biphasic structures composed of both a dense and a nanofibrillar layer (Fig. 1-A). The nanofibers could either be of random orientation (isotropic) or well aligned (anisotropic). Isotropic matrices showed an increase in porosity when increasing polymer solution (96 to 97 %). Mechanical properties were inversely related to matrice porosities. Anisotropic matrices were stiffer than isotropic ones (elastic modulus up to 22 and 2 MPa respectively). hADSC proliferated significantly over 20 days within the scaffolds (up to 5-fold DNA increase), regardless of structure and porosity. The constructs dense polymer layer was favored by the cells up to 10 culture days, but after 20 days, the cells tended to bridge the entire scaffolds thicknesses (Fig. 1-B). This study highlights the potential of biphasic nanofibrillar matrices as substrate for valve engineering, particularly with regards to their elevated mechanical properties and capacity to support cellular population and proliferation.
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Reproducing human heart valves anisotropy with a nanotechnology approach
المؤلفون: Magdi Yacoub, Jerome Sohier and Adrian ChesterTopology and organization of cell environment is an important regulator of differentiation and function. In view of heart valve tissue engineering, we devised a biomimetic scaffold that supports proper cell growth and cell-matrix interactions by reproducing the specific anisotropic fibrillar structure of valves extracellular matrix (ECM). We hypotheseized that high porosity levels of novel nanofibrillar matrices allow extensive cell colonization while nanofiber anisotropy influences cell phenotype. Iso- and anisotropic nanofibrillar structures were obtained with an innovative jet-spraying method that allows the formation polymer nanofibers by the air-stream diffraction of a poly (ε-caprolactone) solution in chloroform. Human adipose derived stem cells (hADSCs) and human valve interstitial cells (hVICs) were rotary seeded (600000 and 500000 cells respectively) on nanofibrillar discs and cultured for 20 days in 10 ml of complete medium under rotation (10 rpm). Isotropic and well aligned nanofibers (anisotropic, 600 nm diameter) were obtained from sprayed polymer (Fig. 1-A). Valve mechanical anisotropy was mimicked by scaffold elasticity, which was increased longitudinally to fiber alignment (from 0.3 to 0.7 Mpa) and decreased orthogonally (from 0.3 to 0.01 Mpa). Further fine-tuning of scaffolds mechanical anisotropy could be obtained by orthogonally associating anisotropic layers of different thickness. Iso- and anisotropic matrices allowed an extensive cellular proliferation (6-fold DNA increase) regardless of cell type. Although cells were more homogeneously distributed within anisotropic scaffolds after seeding, they populated the entire scaffold thickness within 10 days (Fig.1-B) and produced their own ECM (collagen I, III and elastin) regardless of scaffold architecture. Anisotropy induced elongated hADSCs morphology that followed nanofibers' main orientation (Fig. 1-C). hVICS followed the same nanofibers-induced orientation pattern when cultured in anisotropic scaffolds. In conclusion, highly porous anisotropic matrices reproducing valve ECM structure are excellent substrate for cell population while providing an efficient tool to study cells/environment interaction for producing engineered cardiovascular tissues.
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Influence of sedentary lifestyle on body weight in Qatari school children
المؤلفون: Mahmoud Abdallah Alkhateib, Mohammed Al-Zoghbi, Mohammed Saleh and Hamda QutbaBackground & Objectives: School children among the most vulnerable groups that pass critical periods of physical, mental, and developmental growth are in need of special nutrition and health care. Little is known about the nutritional status of school children in Qatar. The aim of the present investigation is to determine the anthropometrics measurements (height, weight and body mass index) of Qatari school children, comparing the study results with the international reference population and to determine the relationship between obesity and lifestyle. Methods: Study was conducted on a sample from Qatari school children. A representative sample (1500 children) were selected between the ages of 6-12 from 23 schools using multistage cluster random sample, while 200 cases from each age group were targeted as primary sampling unit. Data about number of physical education classes, hours of physical activity per week, and information about the sedentary life style were obtained by utilizing a standardized self-administered questionnaire. Results: The current results showed that the percentage of body weight for Qatari children were significantly higher than the reference values while their body height percentage were significantly lower than the reference. Using the WHO (2007) classification of BMI for children, 8%, 16% and 23% of studied children had thinness, overweight and obesity, respectively. The majority of children (55.1%) spent more than 2 hours daily watching TV, surfing the internet or playing electronic games, 25.8% didn't report any kind of physical activity and 48.8% had physical activity less than one hour/day. The current study showed that there is a significant relationship between children's physical activity and prevalence of overweight and obesity. Conclusions: The current work looks at school children in Qatar to create a more complete picture of the current state of health and help to determine how lifestyle and environmental changes can be mitigated as a causal factor of obesity and therefore lifelong poor health.
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What are the changes in oxidative stress and DNA in response to cycling in a thermal challenging environment?
المؤلفون: Wade KnezBackground A hot environment is associated with an increase in core temperature and dehydration. However, there are minimal data investigating the time course of changes in oxidative stress and DNA in response to cycling in a hot environment. Additionally, it is not known whether there is a critical point in core temperature for the production of oxidative stress or DNA modification. Subsequently, this research investigated the time course of changes in markers of oxidative stress and DNA modification during and after exercise in a hot environment. Methods Eight cyclists (age=30.9±2.2yrs; height=177.9±4.1cm; mass=74.5±4.5kg) completed a cycling VO2max in hot conditions (35°C, 70%RH) to determine 60% of peak power output (PPO). One week later they returned and cycled at this intensity until they reached a core temperature of 38.5°C. Blood was sampled before, during, and after (0, 10, 25, 35, post 10 and post 20 mins) exercise to determine changes in oxidative stress and DNA. Statistical analysis was completed using linear mixed models with a level of significance set at p≤0.05. Results Cycling at 60% of PPO until core temperature reached 38.5°C resulted in a significant increase in oxidative stress over the exercise bout. Data showed that oxidative stress increased during exercise period (0-10, 25, 35 min [0 min post]) and decreased from 0-post to post 20 min recovery. After correcting for multiple comparisons, there was a tendency towards significance from 0 mins to the completion of the exercise bout. However, no changes were observed in the modification of DNA during exercise or recovery. No relationship was observed among the changes in blood markers and core temperature. Conclusion Research shows that regular exercise protects against exercise-induced changes in oxidative stress and DNA. This research shows that this relationship extends to exercising in a hot environment. Changes in oxidative stress appeared to be more sensitive to exercise duration than core temperature. Furthermore, these data showed that there was no critical core temperature for the development of oxidative stress. However, the current project was limited to a maximum core temperature of 38.5°C. Future research should continue exercise beyond this point to develop a clearer understanding.
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Predictors of in-hospital mortality among Middle Eastern Arab and South Asian patients hospitalized with atrial fibrillation: Analysis from a 20-year registry in Qatar (1991-2010)
المؤلفون: Amar M Salam, Hajar A AlBinali, Abdul Wahid Al-Mulla, Rajvir Singh and Jassim Al SuwaidiObjectives: Although predictors of mortality have been identified in major atrial fibrillation (AF) clinical trials, most of the data were limited to studies in the developed world and included mainly Caucasian patients. The aim of this study is to identify predictors of mortality in Middle Eastern Arab and South Asian patients hospitalized with AF in a real-world population in a Middle Eastern country. Methods: Retrospective analysis of prospective registry of all patients hospitalized with AF in Qatar from 1991 through 2010 was made. Ethnicity, clinical characteristics and co-morbidities were analyzed in relation to mortality. Results: During the 20 year period; 2857 Arabs and 548 Asians were hospitalized for AF. There were 138 deaths among Arabs and 14 among Asians (4.8% versus 2.6%, p= 0.02). Multivariate analysis of predictors of in-hospital mortality identified chronic renal impairment and acute coronary syndromes as independent predictors of poor outcome among patients hospitalized with AF whereas ethnicity was not [Table]. Conclusions: In this region, the risk of in-hospital mortality for patients hospitalized with AF remains increased in patients who have chronic renal impairment or acute coronary syndromes irrespective of ethnicity. Patients at high risk may benefit from aggressive monitoring and intervention in order to reduce mortality.
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Determining the significance of observed mutations in ovarian tumors using a random expectation model
المؤلفون: Najeeb Halabi, Joel Malek and Arash RafiiBackground and Objectives: Recent next generation sequencing studies of different cancers reveal a varied spectrum of mutations with patients having dozens to hundreds of mutations with little overlap in mutations between different patients. A difficult problem is to understand which of the observed mutations contribute to tumorigenesis. While several approaches have been used to determine significantly mutated genes, these approaches do not calculate random expectation mutation frequencies. Here, we develop a simulation of random mutagenesis and compare observed mutation frequencies (Fo) to random expectation frequencies (Fr) to identify genes that are likely to be selected for or against in tumors. Methods: Our random simulation method, implemented in Matlab, applies a different mutation probability for A or T bases, G or C bases and CpG repeats. Mutation simulation was done on Agilent's 50 Mb exon library. Mutations are reported on a gene level. Each simulation was run for 100 trials with each trial consisting of 316 repeats. The 100 trials enables calculation of standard deviations for random mutation frequencies. We also carried out a bootstrap analysis of observed data to estimate standard deviations of observed mutations. We calculated differences between Fo and Fr using ratio and rank comparisons. Results: We applied our approach to ovarian cancer data reported by the The Cancer Genome Atlas in 2011. We found a significant difference between observed mutations and random expectation mutations. Random mutations correlate well with the length of a gene (R2=0.54 for one trial) while almost no correlation is seen with observed mutations (R2=0.11). We also found one set of genes that is mutated at higher frequencies than expected while another set of genes is mutated at lower frequencies than expected. Conclusions: Our simulated mutagenesis method is a novel approach to determining significance of observed mutations in cancer. Application of this model to ovarian cancer data shows a significant discrepancy between expected and observed mutations possibly indicating that most observed gene mutations are selected for. In addition, our approach reveals specific genes that may be implicated in tumorigenesis. These genes are good candidates for further study.
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The outcomes of sleeve gastrectomy for treatment of morbidly obese adolescents in Hamad General Hospital
المؤلفون: Mohammed Al Kuwari, Michel Gagner, Davit Sargsyan, Moataz Bashah and Mohammed RizwanIntroduction: Obesity is a global problem affecting adolescents and teens with profound psychological and medical sequelae. The role of bariatric surgery in adolescents remains controversial. The aim of the study is to report our results with sleeve gastrectomy in this population. Goal of study: To study the efficacy of sleeve gastrectomy as a treatment for obese adolescents in terms of weight loss, comorbidity resolution and safety of procedure. Methods: Retrospective review of our records of all patients under the age of 19 who underwent laparoscopic sleeve gastrectomy in Hamad General Hospital in the years 2010-2012. Variables studied included; age, BMI, preoperative and postoperative weight, sex, comorbidities, length of stay, operative time, and early or late onset complications. Results: Out of 700 patients from our institute, 37 patients (5%) were adolescents. 45% males N=17 and 55% females N=20. Mean age was 17 ±1.5. Mean length of stay was 3.6 ±0.8. Mean operative time was 64 ±17 minute. Mean preoperative weight 141 ±27 kgs (200-94.) Mean BMI 51±8.8 kg/m2 (72-35). With regard to comorbidities, one person had obstructive sleep apnea and reported resolution. Mean follow up was 8 months (17-1), mean post op BMI 38 ±11.8 kg/m2 (23-70), mean excess weight loss -28% (4-45%). Mortality 0%. Morbidity 0%. Conclusion: Laparoscopic sleeve gastrectomy is a safe option for treatment of obese adolescents. It is particularly effective in this particular group with satisfactory safety profile and adequate weight loss. However, longer follow up is needed to evaluate the long term effects of the surgery.
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