Qatar Foundation Annual Research Forum Volume 2011 Issue 1

Background: The reasons behind the differences in the levels of discordancy (that is one partner testing HIV positive while the other testing HIV negative) among spousal and cohabiting partnerships affected by HIV across sub-Saharan Africa (SSA) remain inadequately understood. Recently, many randomized clinical trials have shown substantial efficacies for several prevention interventions among these partnerships.

Moreover, there has been an intense debate about the priority of HIV prevention interventions among discordant couples relative to other prevention approaches such as among commercial sex networks.

Objective: To describe and explain patterns of HIV infection among spousal and cohabiting sexual partnerships, across a range of settings in SSA.

Methods: Demographic health survey (DHS) data for 20 countries in SSA were used to estimate the prevalence of HIV sero-discordancy among stable partnerships with at least one HIV-infected individual in the partnership (P), prevalence of discordancy among all stable partnerships in the population (S), prevalence of discordancy among the entire sexually active population (A), and prevalence of discordancy among HIV infected individuals (I).

Results: Two distinct patterns of HIV among stable partnerships were observed. Countries with low HIV prevalence had a high discordancy prevalence among P and I ranging from 48.4–87.8% and 30.6–60.0%, respectively, but low discordancy prevalence among S and A ranging from 0.4–6.4% and 0.2–3.8%, respectively. Conversely, countries at hyper-endemic HIV epidemics had a low discordancy prevalence among P and I ranging from 36.3–58.5% and 17.2–46.0%, respectively, but high discordancy prevalence among S and A ranging from 9.3–17.2% and 5.8–8.3%, respectively.

Conclusions: Two distinct patterns of HIV in stable partnerships were observed. In high prevalence settings, many partnerships were affected by HIV but relatively few were discordant, whilst the opposite was true for low prevalence settings. This pattern may be arising from variations in the HIV transmission probability which is dependent on biological and behavioral factors and might also be affected by the frequency of infection from external partners especially in high prevalence countries. These findings may complicate considerations for rolling out prevention interventions among stable discordant partnerships in SSA.

Background: Empirical evidence suggests that HIV incidence rate within stable discordant sexual partnerships in sub-Saharan Africa (SSA) varies between 1.2 and 19.0 per 100 person-years. Estimating HIV incidence rate within stable discordant partnerships is critical for determining the contribution of HIV sero-conversions among these partnerships to total HIV incidence.

Objective: To estimate HIV incidence rate within stable discordant partnerships using nationally representative data and explore potential underlying factors contributing to their variability across a range of epidemic settings in SSA.

Methods: We constructed a mathematical model based on competing-hazards formalism to estimate HIV incidence rate within stable discordant partnerships across 20 countries in SSA. We also used the model to analyze the patterns of HIV discordancy in SSA. The model was parameterized using Demographic Health Survey data and analyses were conducted at endemic equilibrium. Sensitivity analyses were performed to explore the dependence on the dynamical drivers of discordancy.

Results: Our model fitted well the empirical epidemiological measures of HIV discordancy and yielded an estimate for HIV incidence rate among discordant partnerships of 14.7 per 100 person-years (95% CI 9.9–19.4 per 100 person-years). HIV incidence rate ranged between 3.9 and 34.9 per 100 person-years across the countries. We also identified HIV incidence rate within stable discordant partnerships and HIV incidence rate from sources external to the partnership (or equivalently HIV prevalence) as key determinants of the variability in discordancy measures across SSA.

Conclusions: Our estimate for the HIV incidence rate among discordant partnerships agrees well with empirical estimates for this measure. There is however considerable variability across the countries. Biological and behavioral factors including differences in transmission rates such as due to male circumcision, may have contributed to the variability in HIV incidence rates among discordant partnerships across SSA. More research is needed to elucidate the determinants of this variability in incidence rates.

Background: Hepatitis C virus (HCV) currently infects around 2% of the world's population. Among all nations, HCV prevalence ranges from 0.01% in Scandinavia to 3% in North Africa, with one exception: Egypt. Egypt has the highest prevalence of HCV in the world, estimated nationally at 14.7%. Numerous HCV prevalence studies have published various estimates from different Egyptian communities, suggesting that Egypt, relative to the other nations of the world, might be experiencing an intense ongoing HCV transmission.

Objectives: To review all the evidence on the epidemiology of HCV transmission among different population groups in Egypt.

Methods: This was a systematic review following the PRISMA guidelines of all prevalence data on HCV infection in Egypt. Sources of data included PubMed, international organizations' reports and databases, and country-level reports and databases. Measures were classified into different population categories according to risk of infection.

Results: Seventy-four studies have measured HCV prevalence in Egypt in populations at varying levels of risk. Among Egypt's general population, HCV prevalence in pregnant women was 8.6%, and among blood donors it ranged between 9.0% and 23.2%. A nationally representative survey reported a prevalence of 14.7%. Among populations at high risk of infection, HCV prevalence was found to be as high as 58.3% in multi-transfused children, and 87.5% in adult dialysis patients. Among populations at intermediate risk, diabetic children had a prevalence of 3.1%, barbers a prevalence of 12.3%, health care workers a prevalence of 15.7%, and prisoners a prevalence of 31.4%. Common risk factors appear to be parenteral anti-schistosomal therapy, frequent transfusions, injections or surgical procedures.

Conclusion: Egypt has experienced, and possibly continues to experience, a large HCV epidemic. Prevention measures need to be implemented targeting HCV transmission routes such as better infection control practices in health and dental care facilities, hemodialysis centers, and reducing the excessive numbers of non-therapeutic injections.

Urinary bladder cancer is one of the most common cancers worldwide and has a high recurrence rate. It has the highest lifetime cost of care per patient due to long follow-up cystoscopic surveillance after surgery to detect the high risk of recurrence.

This research develops a portable custom cystoscopic procedure to improve the efficiency and accuracy of the bladder cancer surveillance. The system uses a segmented bending mechanism that is inserted into the bladder via the urethra to steer a flexible imaging probe to provide a comprehensive diagnostic tool for review by an urologist as illustrated in Fig. 1. The position and orientation of the camera locating at the tip of the probe can be automatically controlled remotely to scan the entire bladder surface.

The structure of the bending segment is shown in Fig. 2. The segment bending is tendon driven. Four distributed small wires are connected to the segment body via guiding rings. The wires to control the distal segments are also guided through the mechanism via the rings of proximal segments. The bending angle and bending direction of a segment can be controlled by pulling and releasing its four wires accordingly. The design of the mechanism and the forward/inverse kinematics simulation were finished. A mockup model is under construction to verify the proposed design.

Images abstracted from the video are used to reconstruct a 3D panorama of the whole bladder surface. Our 3D and image mosaicking software is under developed by our collaborator at University of Washington, USA.

Background: Chronic hypertension is a deadly disease that affects nearly 30–36% of the adult population in Qatar and the regional. Inositol 1,4,5-triphosphate receptors (IP3R) are intracellular calcium (Ca²⁺) channels that mediate the release of Ca2+ from sarcoplasmic reticulum in response to IP3 binding. A rise in cytoplasmic Ca²⁺ mediated by voltage-dependent L-type Ca²⁺ (CaL) channels and IP3-dependent Ca²⁺ release can enhance vascular smooth muscle cells (VSMC) contractility and determine peripheral vascular resistance.

Objective: The goal of this study is to elucidate the role of IP3R in hypertension.

Methods: Two rat models of hypertension and the A7r5 rat embryonic aortic cells are used in this project. Proteins for western blot were isolated from small mesenteric arteries (SMA) from hypertensive rats and A7r5 cells. Contraction measurements were performed in isolated arterial rings mounted for tension-recording assays. Contraction was induced with KCl and the phospholipase C (PLC) activator m-3M3FBS. The modulation of the vasoconstrictor responsiveness of SMA by IP3R and nitric oxide (NO) was depicted in a pressurized SMA incubated in the presence or absence of 2-APB (IP3R blocker) and L-NAME (NO synthase inhibitor). A7r5 basal Ca²⁺ levels were assessed using a fluorescence Ca²⁺ imaging system.

Results: Our preliminary results show that IP3R is up regulated in SMA from two different hypertensive rat models and following membrane depolarization in A7r5 cells. This up regulation is associated with an enhanced myogenic tone in response to activation of the PLC-IP3 pathway in SMA and with an increased basal Ca²⁺ levels in A7r5 cells. In contrast, pharmacological inhibition of IP3R alters the vasoconstriction response of pressurized vessels. Furthermore, IP3R upregulation and basal Ca²⁺ increase are lost in A7r5 cells treated with Nifedipine (CaL channels blocker) and drugs that block the Calcineurin-NFAT pathway before depolarization with KCl.

Conclusions: These findings improve our basic understanding of the etiology of hypertension by defining the abnormalities of IP3-dependent Ca²⁺ signaling in VSMC. This may provide novel insights into the pathogenesis of hypertension and set the groundwork for developing novel therapeutic targets for the treatment of hypertension.

Each olfactory sensory neuron in the mammalian nose selects just a single member of the large odorant receptor (OR) gene family. The core processes regulating OR selection may involve mechanisms that limit initial OR transcription and once a single OR is chosen, repress subsequent activations. We have used a genetic strategy to monitor the transcriptional permissiveness of the OR gene P2 by inserting an exogenous promoter, the tetracycline-dependent transactivator responsive promoter (teto), into its start site through homologous recombination. We observe that the OR locus limits the expression of the teto: repressing it outside of the wild type P2 zone while allowing sporadic activation from within its zone. Staged conditional expression experiments reveal that the receptor locus becomes fully repressed over time and that this repression does not require the receptor's open reading frame. Further, the exogenous promoter is inhibited by an OR transgene that similarly suppresses the endogenous receptor repertoire. Neurons in which both P2 alleles bear the teto-modified insertion show predominantly monoallelic expression, despite the genetic potential to express both. Finally, we observe that OR genes are expressed from the edge of pericentromeric heterochromatin. These data support a model of initiation of OR choice limited by non-permissive OR chromatin and maintained by repression of the non-selected OR genes.

Background: Single nucleotide polymorphisms (SNPs) may be causally related to breast cancer risk or be indirectly associated with breast cancer risk through linkage disequilibrium with a causal sequence variant. Risk-associated SNPs will have different frequencies among women with or without breast cancer and can be detected using genetic association studies. Recently, several genome-wide association studies (GWAS) have identified novel risk alleles for breast cancer including those related to FGFR2, TNRC9, MAP3K1, LSP1 genes and other locus. Replication in independent population samples is essential for validation of the results of any genome-wide association. Since the genetic variants (SNPs) are common, they are likely to be shared across different populations with diverse ancestry backgrounds. It would be of interest to determine and investigate the potential implications of these novel markers revealed by genome-wide association studies to predict the “sporadic” breast cancer risk and progression in MENA populations.

Methods: Using TaqMan® SNP genotyping assays, we characterize the variation of 9 SNPs (include rs1219648, rs2981582, rs8051542, rs12443621, rs3803662, rs889312, rs3817198, rs13387042 and rs13281615) for 520 patients with sporadic breast cancer and 360 healthy controls in the Tunisian population. The association between the genotypes and breast cancer susceptibility and tumors characteristics was estimated by computing odds ratio (OR) and 95% confidence levels from logistic regression analyses. Association of the genetic marker with the rates of breast cancer overall survival was assessed using univariate analysis.

Results: Two genetic variants in FGFR2 are significantly associated with the risk of breast cancer: rs1219648 AG/GG (OR=1.23, P=0.002) and rs2981582 AG/ AA (OR=1.33, P=0.003). Two significantly increased risks of breast cancer were respectively associated with T allele of rs8051542 in TNRC9 (OR=1.43, P=0.0003) and C allele of rs889312 in MAP3K1 (OR=1.33, P=0.006). The AG and GG genotypes of rs2981582 in FGFR2 have a significant association with a high risk of lymph node metastasis and a decreased overall survival in breast cancer patients.

Conclusion: Our results for the first time replicated the results of breast cancer GWAS in the Arabic population and indicated that some polymorphisms are associated with increased breast cancer risk and disease progress in the Tunisian population.

Background: Prevalence of metabolic syndrome is directly correlated with increasing occurrence of obesity characterized by accumulation of fat in visceral, lower body, and upper body subcutaneous depots. In a number of species, brown adipose tissue (BAT) converts triglycerides into heat by non-shivering thermogenesis, thus controlling the amount of white adipose tissue. Until recently, BAT was thought to be mostly absent in adult humans but now sizeable BAT depots have been visualized by Positron Emission Tomography (PET) and Computed Tomography (CT) scanning. Relatively little is known about the signaling pathways differentially regulated in brown adipocytes compared to white adipocytes. However, our progress of understanding is hindered by the paucity of well-characterized reliable in vitro model systems.

Objectives: The aim of this study is to characterize the only in vitro model of human BAT cell line, and to identify signature genes for BAT, and compounds implicated in the enhancement of brown phenotype.

Methods: A human BAT cell line, PAZ6, was previously created by immortalizing somatic cells using the large T antigen of Simian Virus 40. The expression of BAT associated markers has been verified by real time RT-PCR done on RNA and immunoblot using specific antibodies performed on cell lysates and supernatants, before and after differentiation and treatment with various compounds such as adrenergic receptor agonist (isoproterenol) and PPAR agonist (rosiglitazone).

Results: We have identified several BAT associated markers, including PDRM16 and the 3 adrenergic receptor. This marker is highly expressed in PAZ6 cells compared to the white adipocyte. In addition, we demonstrate that these cells share a common precursor with myocytes but not with white adipocytes. Our results show that several genes are up-regulated after PPAR gamma activation. Moreover, we confirm that these cells respond to Beta adrenergic agonist treatment. Finally, we identify that the transcription factor farnesoid X Receptor (FXR) induces the expression of BAT associated marker following treatment by its agonist : CDCA.

Conclusions: The PAZ6 cells constitute a readily available surrogate for human brown adipocytes to develop pharmacologic strategies to promote BAT expansion and activation.

The prevalence of insulin resistance and diabetes has shown a dramatic worldwide increase. In Qatar, the prevalence of diabetes is twice that of the United States today, possibly due to lifestyle and dietary changes. Diabetes has an enormously adverse impact on the afflicted population leading to patient mortality, morbidity and staggering health care costs to the nation. Untreated or inadequately treated diabetes results in serious health complications including eye, heart, kidney and nerve damage.

Mass spectrometry based molecular profiling is a powerful tool for interrogation of the underlying molecular alterations which define the etiology and patho-physiology of a complex disease such as diabetes. As a part of the QNRF funded study, we have used ultra performance liquid chromatography (UPLC) in conjunction with high resolution quadrupole time of flight mass spectrometry (Q-TOFMS) for proteomic and metabolomic profiling of bio-fluids derived from diabetic and healthy individuals recruited at the Qatar University Hopsital. The overall goal of this project was to investigate the changes in the molecular profiles in the two groups (normal and diabetic) at the protein and small molecule metabolite level and correlate these changes to define putative biomarkers with potentially diagnostic or prognostic clinical value. We have used a “smart pooling strategy” for bio-fluids from each group to enhance disease associated differences. LCMS/MS based metabolomic analysis of the diabetic and normal pre and post meal metabolome was followed by bioinformatics analysis to identify dysregulated metabolites. Additionally, we have used iTRAQ based UPLC-QTOFMS/MS for quantitative proteomic profiling.

These data were taken together for integrated functional pathway analysis to correlate the changes. Furthermore, we have used a validation cohort for targeted quantitation of candidate markers using multiple-reaction monitoring mass spectrometry. The results will be discussed in context of the state of art technology used for studying pathway perturbations resulting in a diabetic phenotype. A part of this study reported at the HUPO2010, won a “young investigator award” for Dr. Cheema. The ARF presents a unique opportunity to present results from this exciting study, deliberate upon the challenges faced and elaborate on the plans for future studies aimed at a mechanistic insight.

Background: The functional relevance of strength and power measures as an index of functional performance (i.e., sprinting speed) in soccer remains unclear.

Objective: The aim of this study was to investigate the relationships among mechanical variables related to strength and power tests and their influences on sprinting speed in professional soccer players across their life-span.

Methods: Isokinetic measures (quadriceps (Q) peak torques and power at 60°/s and 300°/s), kinetic outputs of the counter-movement jump (CMJ), and sprinting speed (the first 5 m split time (i.e., initial speed) and the 15 to 20 m split time (i.e., leading sprint) of a 20 m sprint), were measured in 224 professional soccer players (age 23.7 ± 4.4 y, body mass 71.4±8.8 kg and height 1.75±0.06 m).

Results: The values for each variable for the fast and slow groups are displayed in Table 1. All the mechanical variables were significantly different between the fast and slow players regardless of the results were ranked according to 5 m or 15–20 m times. The results of the multiple regression analyses identified CMJ height as the best predictor of sprinting performance for the 5 m (R=0.39, P=0.000) and 15–20 m (R=0.51, P=0.000) sprint.

Conclusions: All the mechanical variables could discriminate between the fast and slow players. However, a great degree of unexplained variance still remains indicating there may be better mechanical predictors of sprinting speed in soccer players.