Qatar Foundation Annual Research Conference Proceedings Volume 2016 Issue 1
- تاريخ المؤتمر: 22-23 Mar 2016
- الموقع: Qatar National Convention Center (QNCC), Doha, Qatar
- رقم المجلد: 2016
- المنشور: ٢١ مارس ٢٠١٦
441 - 460 of 656 نتائج
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Does the Transmission of Viral Infectious Diseases Depend on Social Network Contacts, Weather Conditions and Animal Ownership? A Look at Common Cold in Qatar
المؤلفون: Nithiya RajaduraiCommon cold is a viral infection of the upper respiratory tract that brings discomfort to people for few days to few weeks. Although, seasonal common cold is widespread during wintertime, the disease can be contracted all year round. Initially common cold was believed to be link to exposure to cold air because of its widespread during that period; the disease has been categorized as infectious disease there after (William and Sheldon, 2009). Common cold can bring about serious economic hardship or downfall to workforce because it often results in absenteeism from work or school (Babak et al., 2009). The disease is the most commonly encountered infectious disease in human and most frequent illness managed by general practitioner. It was reported that about 25 million people visit doctors yearly in the USA alone with common cold (Heikkinen and Jarvinen, 2003). Common cold can be caused by a variety of virus that depends on a number of factors such season and age, with rhinoviruses been the most common cause of common cold. Heikkinen and Jarvinen, 2003 provide extensive literature on common cold that include causes, epidemiology, clinical diagnosis, treatment and prevention. The effect of weather conditions is very crucial in infectious disease modeling. Social network contacts are vital when seeking to understand and predict the spread of infectious diseases inhuman populations. The transmission of infectious disease has been linked to social contact behavior (Willem et al., 2012, Wallinga et al., 2006) and animal contacts (Kifle et al., 2015, Jones et al., 2008). The frequency of infection may depend on the number of social and animal contacts. The spread of infectious disease can be control through understanding the dynamics of social contact behavior and animal contact. It is reported that adults get the illness two to three times in a year while children are infected five to seven times a year (Babak Amra et al., 2009, Heikkinen and Jarvinen, 2003) The objectives of this project are: a) To explore the dynamics of transmission of the common cold between different age groups. b) To investigate the effect of social contact patterns on the disease incidence. c) To estimate the effects of other associated risk factors such climatic and environmental variables. d) To investigate the effect of socioeconomic background such as family size, education, contact type and so on. To explore the influence of animal ownership on the frequency of the infectiousness. Conceptual Framework and data collection This study will look at the relationship between common cold and climatic changes with the effects of social contact through the development of flexible predictor statistical models. We shall combine flexible statistical models for network data to study these relationships. The data sets will be collected by the undergraduate students over a period of 3-4 months within Qatar through the use of surveys. The social network contact survey which includes the illness status and some demographic variables will be conducted within and outside Qatar University. Recruited participants will cut across different age groups, nationality and gender. An adapted version of the social contact survey POLYMOD (Improving Public Health Policy in Europe through the Modelling and Economic Evaluation of Interventions for the Control of Infectious Diseases) will be used for contact diaries. The participants will be asked if they could be contact again via email or telephone (in a month or so) for completion of the second diary. Firstly, they will be asked to answer few demographic questions such as, the number of family member, age, gender, country and educational attainment. Secondly, for each participant, the daily number of social contacts will be recorded as well as contact type. Participants will be asked if they engaged in a direct conversation with someone else at most three meters away or touched someone else (e.g. shaking hands or kisses on the chick), this was considered as a “physical” contact, even if not a word was spoken. In additional to social network contact, participants will be asked about their interaction with animal. Ownership of animal which is defined as having at least one live animal in the household in which the participant was spending the majority of his/her time. Animals with be categorized into four classes: pets (cat, dog, fish), livestock (horse, sheep, camel, cow), poultry (chicken, turkey, pigeon) and “other”. And lastly, each participant will be asked about his/her illness status will be asked (such as onset date and severity). The climatic data sets that will be used are mean daily temperature, humidity and dust aerosol. The collection of the daily climatic data will commence at least a weeks before the survey. Few weeks later (between 2-4 weeks), participants will be contacted again via email or telephone with similar follow-up questionnaire for the second social contact diary. Modeling techniques Logistic regression is a technique used for making predictions when the dependent variable is a dichotomy, and the independent variables are continuous and/or discrete. For analysis of social network data (clustered), random effect term will be added to the regression model to account for the correlation in the data. The resulting model is a mixed model including the usual fixed effects for the regressors plus the random effects in the predictor. Development of generalized linear mixed models (GLMM) for dichotomous data has been an active area of statistical research. Several approaches, usually adopting a logistic or probit regression model and various methods for incorporating and estimating the influence of the random effects, have been developed. The mixed-effects logistic regression model is a common choice for analysis of correlated dichotomous data and is arguably the most popular GLMM.
References
Babak A, Hamid S, Shahin S, Mohammad G. (2006) Prevalence of the Common Cold Symptoms and Associated Risk Factors in a Large Population Study. Tanaffos 5(3): 13-17.
Heikkinen T, Jarvinen A. (2003) The common cold. The Lancet, 361 (9351): 51-59.
Jones K, Patel N, Levy M, Storeygard A, Balk D, Gittleman J, et al. (2008) Global trends in emerging infectious diseases. Nature 451: 990-993. doi: 10.1038/nature06536 PMID: 18288193.
Kifle YW, Goeyvaerts N, Van Kerckhove K, Willem L, Faes C, Leirs H, et al. (2015) Animal Ownership and Touching Enrich the Context of Social Contacts Relevant to the Spread of Human Infectious Diseases. PLoS ONE 10(7): doi:10.1371/ journal.pone.0133461.
Wallinga J, Teunis P, Kretzschmar M. (2006) Using data on social contacts to estimate age-specific transmission parameters for respiratory-spread infectious agents. American Journal of Epidemiology 164: 936-944.
Willem L, Van Kerckhove K, Chao DL, Hens N, Beutels P. (2012) A Nice Day for an Infection? Weather Conditions and Social Contact Patterns Relevant to Influenza Transmission. PLoS ONE 7(11): doi:10.1371/journal.pone.0048695.
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AMPK Activation Attenuates Albumin-induced Alterations in Renal Tubular Cells In Vitro
المؤلفون: Soumaya Allouch and Shankar MunusamyBackground: Chronic kidney disease (CKD) is characterized by progressive decline in renal function; if left untreated, it ultimately results in end-stage renal disease (ESRD), a condition that demands either dialysis or kidney transplant for survival. CKD and ESRD are associated with a multitude of complications ranging from increased hospitalization to accelerated cardiovascular events and mortality. Currently, type-2 diabetes and hypertension are the two major risk factors for CKD. With the increasing incidence and prevalence of these conditions globally, the patient population with CKD is expanding worldwide. According to local sources, CKD affects about 13% of Qatar's population, and the prevalence of ESRD, the advanced phase of CKD, in Qatar was found to be 212 per million patients. The increased risk of complications associated with CKD in conjunction with its high prevalence in Qatar and in the rest of the world, necessitates its prevention and management as a high national and international priority. Elevated urinary albumin excretion (commonly referred to as proteinuria) is not only a hallmark of renal disease, but also strongly associated with the development and progression of CKD. Albuminuria is thought to induce endoplasmic reticulum (ER) stress, consequently triggering AKT pathway and resulting in inhibition of AMP-activated kinase (AMPK). AMPK, a fuel sensor present in cells, is primarily involved in the regulation of fatty acid oxidation and ATP synthesis. Inactivation of AMPK was found to trigger mTOR (mammalian target of rapamycin) pathway, and subsequently inhibit autophagy (a defense mechanism) and induce epithelial-to-mesenchymal transition (EMT). These signaling changes eventually accelerate renal cell apoptosis, and manifest into CKD. Thus, the objectives of this study are: 1) to standardize and characterize an in vitro model of albumin-induced renal cell injury using normal rat kidney proximal tubular (NRK-5E) cells, and 2) to explore the effect of AMPK activation on ER stress, AKT, mTOR, EMT, autophagy and apoptosis that are thought to mediate renal cell injury during proteinuria using the developed in vitro model of albumin-induced renal cell injury. Methods: NRK-52E cells were grown to 60% confluency and then serum-starved for 24 hours to arrest cell proliferation. Cells were then exposed to albumin, at concentrations ranging from 1 to 30 mg/ml, for 24 to 72 hours. At specific endpoints, cells were assessed for induction of ER stress and alterations in the status of AKT, AMPK, mTOR and autophagy and changes in cellular senescence via x-galactosidase (an enzyme that is expressed in senescent cells) staining. Following standardization of albumin-induced renal cell injury model, studies were performed in the presence and absence of AMPK activator metformin (1 mM) for 24 to 72 hours. Cells were then assessed for alterations in the status of AMPK, AKT and mTOR, and the markers of ER stress, EMT, autophagy and apoptosis. Results: Exposure to albumin for 72 hours caused a dose-dependent increase in cellular senescence in NRK-52E cells. In contrast, cells exposed to albumin for 24 and 48 hours did not reveal any marked changes in cellular senescence. A 4-fold induction in ER stress marker CHOP and the EMT marker a-SMA was noted. Moreover, higher concentrations of albumin, particularly 30 mg/ml, caused severe induction of ER stress and EMT, marked by 20-fold increase in CHOP and 6-fold increase in a-SMA respectively. Similarly, the phosphorylation of AKT and P70S6K (a downstream target of mTOR) was increased by more than 1.5-fold in cells subjected to albumin treatment. In addition, albumin treatment caused a dose-dependent reduction in AMPK phosphorylation and about 66% decrease in the expression of autophagy marker LC3-II. The above changes were observed in conjunction with prominent dose-dependent induction of apoptotic markers - caspase-3 and caspase-12 ranging between 1.5 to 3.5-fold and 3 to 5-fold respectively in cells exposed to albumin. In contrast, metformin co-treatment restored the levels of phosphorylated AMPK, and suppressed activation of AKT and P70S6K in NRK-52E cells exposed to albumin. Notably, metformin also prevented albumin-induced EMT; this was marked by a 50% decrease in a-SMA and a 60% increase in E-cadherin expression. In addition, 2.5-fold increase in LC3-II expression was noted. Intriguingly, the pro-apoptotic protein CHOP was induced following treatment with metformin; nonetheless, the expression of apoptotic markers caspase-12 and caspase-3 was reduced by 80% and 70% respectively, indicating that metformin protected the cells against albumin-induced apoptosis. Conclusion: Albumin treatment induces ER stress, and activates AKT, EMT and apoptosis, with concomitant decreases in autophagy and inactivation of AMPK in renal tubular cells. Activation of AMPK via metformin treatment suppresses AKT and mTOR activation, and prevents EMT and apoptosis, but increases autophagy and ER stress in renal tubular cells. Further studies are required to understand the mechanisms by which metformin differentially modulates ER stress and apoptosis in renal cells under proteinuria. Together, our findings suggest that AMPK activation via metformin could serve as a potential therapeutic strategy to prevent and/or treat the development of CKD in patients with established proteinuria.
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Antimicrobial Modification of LDPE Using Non-thermal Plasma
المؤلفون: Salma Habib, Mariam Ali S A Al-Maadeed and Anton PopelkaLow-density polyethylene (LDPE) represents polymer having good chemical and physical characteristics for which it is widely used in many applications, such as biomedical and food packaging industry. This polymer excels by good transparency, flexibility, low weight and cost which makes it suitable material compared to non-polymer packaging materials. However, its hydrophobicity cause many limitations for antimicrobial activity which can result in absence of some characteristics required in food packaging applications. For that purpose, some researches have done experiments to modify the polymer surface to increase the surface free energy (hydrophilicity). This can be done by introducing some polar functional groups into the LDPE surface which will permit an increment of its surface free energy and so its wettability or adhesion without any disruption in its bulk properties [1]. One of the most preferable modification techniques is known as non-thermal radio-frequency discharge plasma, and it is preferred technique due to the ability to modify only thin surface layer leading to noticable improvement of the surface properties [2].Moreover, it represents environmentally friendly technique since it does not require the use of any hazardous chemicals or dangerous radiations and therefore non-thermal plasma is highly recommended for food packaging applications [1]. In addition, the surface modification of LDPE can lead to the enhancement of the antimicrobial activity, which was the main purpose of this research. Food packaging materials requires preventing any growth of bacteria, fungal, or any other microbial organisms for health and food safety. Some approved preservatives are commonly used directly in foods to preserve them form microorganisms growth and spoilage. Nowadays, some innovative ways are applied to graft acrylic acid on polymers surfaces [3] for biomedical applications to create an effective layer for an immobilization of antibacterial agents and this results in bacteria prevention on the LDPE surface. In this research, we focused on grafting of sorbic acid as one of the most commonly used preservatives in food and beverage for being safe, and effective in bacteria inhibition (whether pathogenic strains or spoilage kinds), molds, and yeasts [4]. It is also used in cosmetic industries since it has good compatibility with skin and it is easily usable [5]. For the potential enhancement of the antimicrobial efficiency, chitosan representing antimicrobial agent was used for the immobilization on sorbic acid created layer. Chitosan (a derivative of chitin polysaccharide) was chosen as a natural occurring antimicrobial agent (from crabs shrimps, and other sea shells [5]) that has strong and effective antimicrobial activity along with its nontoxicity, biofunctionality, biodegradability, and biocompatibility [6]. In this study, the LDPE surface was modified by several modification steps. The first step involved the modification of the LDPE surface by non-thermal radio-frequency discharge plasma as a radical graft initiator for the subsequently polymerization of sorbic acid containing double bonds. In the next step, grafting of sorbic acid was carried out immediately after plasma treatment allowing the interaction of plasma created radicals on LDPE surface with sorbic acid. Final step was focused on the immobilization of chitosan on grafted sorbic acid platform. Each modification step was analyzed by different analytical techniques and methods to obtain detailed information about the modification process. The surface parameters changes after modification of the LDPE surface, such as surface free energy (contact angles measurements), graft yield (gravimetric measurements) surface morphology (scanning electron microscopy and atomic force microscopy) and chemistry (Fourier transform infrared spectroscopy with attenuated total reflectance) were obtained allowing understanding the modification process.
Acknowledgement
The authors gratefully acknowledge use of the services and facilities of the Center for Advanced Materials (CAM) and Central Laboratory Unit of Qatar University, Qatar.
References
[1] S.K. Pankaj, C. Bueno-Ferrer, N.N. Misra, V. Milosavljević, C.P. O'Donnell, P. Bourke, et al., Applications of cold plasma technology in food packaging, Trends Food Sci. Technol. 35 (2014) 5-17. doi:10.1016/j.tifs.2013.10.009.
[2] T.D. Martins, R.A. Bataglioli, T.B. Taketa, F.D.C. Vasconcellos, M.M. Beppu, Surface modification of polyelectrolyte multilayers by high radio frequency air plasma treatment, Appl. Surf. Sci. 329 (2015) 287-291. doi:10.1016/j.apsusc.2014.12.010.
[3] A. Popelka, I. Novák, M. Lehocký, I. Junkar, M. Mozetič, A. Kleinová, et al., A new route for chitosan immobilization onto polyethylene surface., Carbohydr. Polym. 90 (2012) 1501-8. doi:10.1016/j.carbpol.2012.07.021.
[4] S.S. Sumner, J.E. Marcy, The Effect of Sorbic Acid on The Survival of Staphylococcus aureus on Shredded Cheddar and Mozzarella Cheese By Alison K. Roberts Thesis submitted to the Faculty of Virginia Polytechnic Institute and State in partial fulfillment of the requirements for t, (n.d.). http://scholar.lib.vt.edu/theses/available/etd-03102003-151240/unrestricted/ALISONTHESIS.pdf.
[5] F. Devlieghere, A. Vermeulen, J. Debevere, Chitosan: antimicrobial activity, interactions with food components and applicability as a coating on fruit and vegetables, Food Microbiol. 21 (2004) 703-714. doi:10.1016/j.fm.2004.02.008.
[6] M. Aider, Chitosan application for active bio-based films production and potential in the food industry: Review, LWT-Food Sci. Technol. 43 (2010) 837-842. doi:10.1016/j.lwt.2010.01.021.
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The Impact of Long-term Medicines Use: Linguistic Validation of the Living with Medicines Questionnaire
المؤلفون: Amani ZidanIntroduction: Polypharmacy (or the use of multiple medications at the same time by the same patient) could expose the patient to health risks and add an extra burden on the life of these patients in addition to the burden of illness. The Living with Medicines Questionnaire (LMQ) was developed to assess the burden of polypharmacy from the patient's perspective. This tool includes items relating to the use of medication and expressed as statements for which the respondents indicates his/her agreement using five-points Likert-type. There is a need to make available such a measure to contribute information generated from the Arabic-speaking world and to share research findings through an Arabic version of the LMQ, which is culturally equivalent to the original English tool. Objectives: We aimed at translating and culturally adapting the Living with Medicines Questionnaire into the Arabic context through a structured process utilizing best practices in translation and cultural adaptation. Methods: As means for adhering to best practice, permission to use the LMQ was sought from the developers, and a protocol for its translation and cultural adaptation was developed using guidelines developed by the International Society for Pharmacoeconomics and Outcomes Research (ISPOR) for the translation and cultural adaptation process for patient-reported outcomes measures. Two forward translations were produced, compared, and reconciled into the first reconciled version. This version was then back translated into English and compared with the original tool leading to the second reconciled version. The emerging Arabic version of the LMQ was cognitively tested among purposively selected individuals to test the linguistic and cultural equivalence and produce the final Arabic translation. The results were documented and shared with the developers of the LMQ. Results: A comprehensive protocol, with the potential to inform future similar studies elsewhere, was developed and used as a guide to produce an Arabic version of the LMQ that is representative of the original tool, and suitable for the Arabic culture. No major issues were found in the demographics section of the questionnaire or the instructions to answer the questions. Issues identified and related to cultural and linguistic equivalence of some terms were resolved by re-wording some items in the tool. A total of seven people were purposively selected to be interviewed in order to assess the LMQ Arabic version in areas related to comprehension, time burden, and acceptability. Individuals were selected with consideration to balanced gender distribution, age, ethnicity/nationality, education, and all with Arabic language as their mother tongue. The cognitive debriefing exercise generated comments regarding the original tool's construct and its Arabic equivalent, which were communicated to the developers of the LMQ for their consideration while conducting further comparative studies. Conclusion: Through following methods based on best practice, we have joined the international efforts into the development of the first questionnaire aiming to measure medication burden in the Arabic-speaking region. We now make available a culturally equivalent Arabic translation of the Living with Médicines Questionnaire for use in Arabic speaking countries in research and/or clinical practice. However, further validation tests are needed to be conducted among Arabic-speaking population.
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Anti-proliferative and Anti-metastatic Effect of Aqueous Extract of Origanum Syriacum on Aggressive Human Breast Cancer Cells
المؤلفون: Amal Shahada Alkahlout, Ali Eid, Ipek Goktepe and Alaeldin SalehAround the world as well as in Qatar, breast cancer is characterized among the highest rates of mortalities that are cancer related. Alarmingly, statistics have shown that the incidence of breast cancer is slightly higher in Qatari women than other Arab countries in the region. This evidence suggests the importance of focusing research on understanding and treatment of breast cancer in Qatar. Current treatment options for breast cancer includes; chemotherapy, surgery, and radiotherapy. Chemotherapy and radiotherapy are associated with undesired side effects; thus, many people tend to look for alternative treatments. Herbal treatments have been used as an alternative to traditional cancer therapies in recent years. Several studies have shown that herbs contain bioactive compounds, including flavonoids, steroids, as well as others, which exert anti-oxidative, anti-proliferative, and anti-inflammatory properties. One of the most commonly used herbs in the Arabian Gulf region is Origanum syriacum. It is known to have anti-oxidative effect. Unfortunately, studies are extremely limited in terms of understanding its anti-carcinogenic effect. Therefore, this study was carried out to determine the effect of O. syriacum aqueous extract (OSE) on an aggressive type of breast cancer (MDA-MB-231) cells. O. syriacum extract was prepared by dissolving the ground dried leaves in water and then drying it using a rotarvapor. Viability of MDA-MB-231 cells in the presence or absence of increasing concentration of OSE was examined by MTT assay. The flow cytometry was used to test the cell cycle progression in the presence of OSE. Moreover, the migratory capacity of MDA-MB-231 cells was determined by Boyden chamber and scratch assay. The invasiveness of MDA-MB-231 in the absence and presence of OSE was investigated using the Matrigel coated wells. Furthermore, adherence of MDA-MB-231 cells to fibronectin was tested with and without OSE. The oxidative stress of the different concentrations of OSE against MDA-MB-231 was determined using ROS-glo assay. Finally, western blot analysis was performed to test the metastatic ability (occludin expression) as well as autophagy marker (LC3A/B expression). The results indicated that OSE decreased the proliferation of MDA-MB-231 cells in a time and a concentration dependent manner. The highest anti-proliferative effects of OSE were observed at concentrations of 0.8 mg/ml and above after 24, 48 and 72 hrs of exposure. Furthermore, OSE arrested cells in G1 phase of cell cycle. Also, migratory capacity of MDA-MB-231 cells declined in the presence of OSE at a concentration of 1.2 mg/ml. Moreover, OSE inhibited the adhesive property along with the invasiveness of aggressive breast cancer cell line. Supporting the above results, an increase in occludin expression was observed in cells treated with OSE indicating that O. syriacum extract has an anti-metastatic capacity. Additionally, the production of ROS as well as the expression of LC3A/B proteins increased in MDA-MB-231 cells treated with OSE at concentration of 1.2 mg/ml. Our results demonstrate that Origanum syriacum may have a potential to be used as a supplemental therapy for patients suffering from malignant breast cancer. Further insight into understanding molecular mechanisms and safety of OSE using in vivo studies should be carried out to fully understand its activity at the molecular level and determine its safe use in the treatment/prevention of breast cancer.
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Antibiotic Susceptibility and Plasmid Profile of Vibrio Vulnificus Isolated from Mussels in Qatar
المؤلفون: Mohammed Aldulaimi, Sahila Abd.Mutalib, Màaruf Abd.Ghani and Noura AlhashmiAntibiotic Susceptibility and Plasmid Profile of Vibrio vulnificus isolated from mussels in Qatar Vibrio vulnificus infections are the worldwide public health problems associated with illnesses resulting from consumption of raw or partially cooked seafood and exposure with the contaminated sea water. Infections of V. vulnificus are reported in many different countries in America, Europe and Asia notably in USA, South Korea, Taiwan, Malaysia and Saudi Arabia. The aim of this study is to isolate and identify V. vulnificus from Mussels in Qatar and detect antibiotic susceptibility and plasmid profiles. A total of 87 Mussels, 50 from Doha and 37 from Akhor were examined for the presence of V. vulnificus using Thiosulfate-citrate-bile salts-sucrose agar (TCBS) and Chromagar Vibrio (CV), 18% of Doha samples were positive and 13.5% of Alkhor samples were positive, 9 of 14 isolates from Doha and 5 of 14 isolates from Alkhor. The antibiotic susceptibility tests were performed for 12 antibiotics by the disc diffusion method. For molecular identification of the isolates, the 16S ribosomal RNA gene fragment was amplified by polymerase chain reaction (PCR) and the nucleotide data were subjected to Basic Local Alignment Search Tool (BLAST) for analysis, Sequence comparison with public databases resulted in 96-100% similarity with V. vulnificus in 15 (60%), 99-100% similarity with V. paheamolyticus in 5 (20%); and 5 (20%), were identified as the non-vibrio species, The analysis of evolutionary relationships among isolates in this study was represented in seven cluster groups. The cluster A referred to non-vibrio isolates whereas the clusters B, C, E, F, and G included V. vulnificus.
V. paraheamolyticus was only represented in the cluster D. 16S rDNA-based identification confirmed the conventional identification for isolates. The morphological and biochemical test detected V. vulnificus in 32% of the Mussels samples all of which showed resistance for two to eight antibiotics. Plasmids were found in 88% of the isolates with 10 different profiles having two to four plasmids. Based on 16S rRNA gene sequence homology 15 isolates were identified as V. vulnificus, five as other Vibrios and five as nonvibrios. We have observed a marked difference between morphological methods and molecular methods in identification of V. vulnificus indicating the in adequacy of the morphological technique in discriminating the Vibrio species. The occurrence of V. vulnificus in the Mussels samples is quite high so consumption of uncooked and semicooked Mussels should be avoided in order to prevent food-borne infection by this pathogenic bacterium. There are observed a marked difference between morphological methods and molecular methods in identification of V. vulnificus indicating the in adequacy of the morphological technique in discriminating the Vibrio species. The occurrence of V. vulnificus in the cockle samples is quite high so consumption of uncooked and semicooked cockles should be avoided in order to prevent food-borne infection by this pathogenic bacterium. Antibiotic susceptibility. Bacterial isolates showing resistance to more than six antibiotics contained more than three plasmids. Plasmids are known to carry antibiotic resistance genes. Otherwise, V. vulnificus isolates in which no plasmids could detected also has resistance to some of antibiotics, that mean antibiotic resistance genes may also be carried on the chromosome of bacteria.
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Predicting Weight Loss in Online Social Media
المؤلفون: Tiago Oliveira Cunha, Ingmar Weber and Hamed HaddadiObesity is a major public health problem which adversely impacts mortality and quality of life, also it is associated with significantly increased risk of more than 20 chronic diseases and health conditions [Thiese et al., 2015]. According to the World Health Organization, the prevalence of obesity has nearly doubled within the last 30 years, which has led to an impressive estimate of 402 million obese people worldwide. The etiology of obesity is complex and encompasses a wide range of genetic, physiological, behavioral, cultural, social and environmental factors. Before the appearance of online social media, factors associated with obesity could only be measured in the real-world. However, with social environments moving online, the escalating number of interactions in online communities has created a great opportunity to study huge amount of user-generated content that comprises various topics related to obesity. These topics include people's experiences, recommendations and feedback about certain medications, medical procedures, diets or exercises, and emotional support in the form of encouragement, sympathy, and success stories. Analyzing and exploring these topics can give health practitioners various insights into community dynamics, such as the effects of online social support on community members and the profile of influential members, as well as provide important information to design effective online health intervention strategies [Bennett and Glasgow, 2009]. Online communities can be used to understand and promote health behavior as well as disseminate health innovations. But still little is known about how these communities can help enhance health conditions, such as weight loss. Advantages of online communities include access to many peers with the same health concerns, convenient communication spanning geographic distances, and anonymity (if desired) for discussion of sensitive issues [Hwang et al., 2010]. In this study, we are interested in answering the research question of whether it is possible to use online user generated content to predict success or failure of weight loss and weight maintenance. Concretely, this work investigates if there is a relation between online users behavior and the likelihood of them losing weight in an online Reddit weight loss community, namely “loseit”. Data collected include posts, comments and other metadata (i.e., timestamp, user name, number of upvotes) from August 2010 to November 2014.
In total, we obtained 70, 949 posts and 922, 245 comments. These data were generated by 107,886 unique users. The community encourages users to post their weight and progress along time, sharing experiences. Our aim is to show that social media can be exploited to help health practitioners to understand obesity dynamics, delivering more personalized treatments and improving patient-centered care. In this direction, our findings aid health practitioners to design early warning systems or effective online health interventions strategies that can be incorporated into social media platforms and lead to more effective treatment. These systems may provide great benefit to patients, for example, by integrating recommendation systems that can help users make important decisions, such as choosing the right type of diet or exercise for their obesity condition. We believe that exploring novel approaches to understand and address obesity is crucial to realize Qatar's National Vision 2030 of a healthy population.
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Inhibition of the Akt Kinase Down-regulates ERK, Bcl-2 and Survivin and Suppresses Proliferation and Survival of Murine VEGF-dependent Angiosarcoma Cells
Introduction: Angiosarcomas are rare and malignant neoplasms that involve abnormal proliferation and migration of cancerous endothelial cells. Angiosarcomas can arise in any region of the body, but tend to be found in the skin, soft tissue, and liver. They are associated with high mortality rate due to their aggressiveness and high rate of metastasis. Therapeutic strategies for treating angiosarcomas involve use of cytotoxic drugs and radiotherapy. However, patient-resistance to these approaches is commonly reported. Hence, there is a need to further understand molecular mechanisms underlying angiosarcomas and explore novel therapeutic targets. Furthermore, because abnormal angiogenesis underlies nearly all types of cancer, a better understanding of cellular pathways regulating cancer endothelial cell function may also lead to development of novel anti-angiogenic therapies. The PI3K/AKT/mTOR signaling pathway plays an important role in regulating cell proliferation and is also regarded as one of the most commonly dis-regulated pathway in cancer. Inhibitors have been developed targeting these signaling proteins and their therapeutic potential has been evaluated in different studies. However, there is little known about the relevance of this signaling pathway to angiosarcomas. Therefore, in this study, we explored the anticancer therapeutic potential of targeting the PI3K/AKT/mTOR signaling pathway using inhibitors of PI3K, AKT or mTOR in a murine VEGF-dependent angiosarcoma cell line. Methods: Cell culture: MS1-VEGF cells (mouse endothelial cells capable of inducing angiosarcomas) were used. Cells were maintained in Dulbecco's Modified Eagle Medium, which was supplemented by 5% fetal bovine serum, 1% penicillin/streptomycin, and 11 mM glucose. Concentration-response experiments: The inhibitors used were: PI3K - LY294002 (10 μM); Akt – AKTi 1/2 inhibitor (AKTi, 10 μM); and mTOR - Temsirolimus (4 μM). LY294002 is a selective inhibitor of PI3K, but is not yet in clinical use. AKTi 1/2 is a non-ATP competitive inhibitor of Akt isoforms 1 and 2. Temsirolimus is a specific inhibitor of mTOR, and has been clinically used for the treatment of advanced renal cell carcinoma. The treatments were conducted over a 48 h period, with DMSO serving as the solvent control. Experiments was repeated at least three times using cells cultured in 12 or 6-well sterile tissue culture plates (Falcon). Cells were incubated in a 5% CO2 incubator at 37 °C. At the end of the treatment period, cell counts were performed and trypan blue dye exclusion was used to assay cell viability. This was done by pipetting a small volume of cell suspension mixed with trypan blue onto a dual chamber counting slide (Bio-Rad TC20 Automated Cell Counter). Proliferation Assay: In order to further assess the effectiveness of the inhibitors, proliferation assays were performed. Cells plated in 96-well plates with the inhibitors for 48 h were treated with the CellTiter 96 Aqueous One Solution reagent (Promega) and incubated in the CO2 incubator at 37 °C for 3 h. A PerkinElmer 2104 plate reader was used (EnVision software) to measure absorbance (at 492 nm). Western blots: Western blots were used to detect the expression of several proteins linked to the PI3K/Akt/mTOR pathway and also to study changes resulting from treatment with inhibitors. Primary antibodies recognizing mTOR, AKT, PI3K, eNOS, LC3B, Beclin-1, ERK, Survivin, and Bcl-2 were used. All proteins probed have known roles in cell proliferation/apoptosis/autophagy. Images were captured using GeneSnap software on a PerkinElmer Geliance 600 imaging system. Quantitiy One (Biorad) was used to analyze Western blot data. Flow cytometry: Cell cycle analysis was performed on the LSR Fortessa analyzer (BD Biosciences) by staining fixed and permeabilized cells with propidium iodide. Data was processed with FACS Diva 8.0 software (BD Biosciences). Data analysis: All the data was analyzed using the statistical software GraphPad Prism 5.0 (GraphPad Software, Inc. CA, USA). Data is presented as mean ± SEM. Statistical analysis was performed with using ‘t’ test or one-way analysis of variance (ANOVA). Post-hoc comparisons between groups after ANOVA were performed by Tukey's multiple comparison tests. ‘p’ values less than 0.05 were considered to be statistically significant. Results: Incubation of MS1 VEGF cells with LY294002, Akt-i ½ or Temsirolimus caused a reduction in cell number, indicating reduced cell proliferation. The Akt-i ½ was the most effective among the three and also caused a strong reduction ( < 25% viability) in cell viability (unlike LY294002 and Temsirolimus). Proliferation assays performed in 96-well plates indicate a reduction in MS1 VEGF cell proliferation with all three inhibitors, and Akt-i ½ was again the most effective in these assays. Cell cycle analysis revealed a robust increase in ‘sub G0/G1 population’ after treatment with Akt-i ½ (Control - 8% vs Akt-i ½ - 43%), suggesting an increase in cell death. To investigate the mechanisms underlying the actions of the inhibitors, western blot experiments were performed. The data (n = 4) demonstrated down-regulation of the anti-apoptotic Bcl family protein Bcl-2 and the inhibitor of apoptosis protein survivin after treatment with Akt-i ½ (but not LY294002 or Temsirolimus). Treatment with Akt-i ½ also reduced the phosphorylation of Akt and ERK proteins. Furthermore, there was a strong increase in the expression of the autophagy marker LC3B-II after treatment with Akt-i ½. Immuno-staining experiments confirmed aggregation of LC3B-II after Akt-I ½ treatment, suggesting an induction of autophagy. Inhibition of autophagy by 3-methyladenosine (3-MA) reversed Akt-i ½-induced LC3B-II puncta formation and also significantly enhanced Akt-i ½-induced cell toxicity. This suggests that autophagy induction acts as a cell survival mechanism after Akt inhibition. To investigate if Bcl-2 and survivin could be downstream effectors of Akt-i ½, experiments were performed using specific inhibitors: YM155 for survivin and TW37 for Bcl-2. A combination of YM155 and TW37 induced robust changes in cell cycle, increased the ‘sub G0/G1 population’ (Control - 9% vs. TW37 + YM155 - 38%) and reduced the proportion of cells in G0/G1, S as well as G2/M phase. Discussion: The data revealed promising anti-proliferative actions for LY294002, Temsirolimus and Akt-i ½ in MS1 VEGF cells. The drug, Akt-i ½, drug was particularly effective and also substantially reduced cell viability. The data also suggest that Bcl-2 and survivin may be critical components of the anti-proliferative action of Akt-i ½ thus making it a highly effective agent. The data also revealed that the cells induced autophagy as a survival mechanism when Akt was inhibited. In conclusion, multiple signaling pathways and proteins regulate MS1 VEGF cell proliferation and survival, which are targeted by Akt-i ½. Future studies: Future investigations will focus primarily on direct evaluation of apoptosis by flow cytometry and if possible experiments in nude mice to evaluate in vivo drug efficacy.
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Evaluation of a Cumulative Performance-based Assessment for Pharmacy Students in Qatar
المؤلفون: Ahmed Sobh, Kyle John Wilby, Mohamed Izham, Mohammad Diab and Zubin AustinBackground: Objective structured clinical examinations (OSCEs) are considered the most psychometrically robust form of clinical skills assessment in the health professions. In 2014, the College of Pharmacy at Qatar University (CoP-QU) piloted the first cumulative OSCE for graduating students in collaboration with the Supreme Council of Health and the University of Toronto. Since then, interest has grown in measuring the psychometric properties of this examination to ensure adequate reliability, validity and defensibility. Objectives: This study aimed to evaluate the psychometric properties of the OSCE conducted in 2015 at the CoP-QU. A secondary objective of this study was to identify quality improvement opportunities for design, implementation, and evaluation of the OSCE. Methods: The psychometric analysis occurred as follows: We calculated cut scores and pass rates of the 10 stations being used in the OSCE assessment using borderline regression method. Predictive validity of undergraduate courses grades with OSCE grades were calculated using correlation and regression statistics. Concurrent validity of similar cumulative exams were evaluated using Pearson correlation. Risk of bias was calculated using Spearman correlation between assessors' analytical (checklist sheet of required tasks to be performed in a station) and global (the score of whole performance including communication skills on a scale from 1 to 5) scoring. Content validity was assessed quantitatively using 18 student-feedback forms and qualitatively through focus groups with OSCE participants and contributors (total of 5 assessors, 3 students, 3 administrators, 3 standardized patients). Interrater reliability was assessed using intra-class correlation coefficients (ICCs). Construct validity was evaluated by comparing interrater reliability between the first and second OSCE cycles. Cronbach's alpha was used to determine internal consistency of students' performance in all stations in terms of global and total scores. Correlation statistics were conducted at α level < 0.05. Results: Out of 50% allocated for global score and 50% for analytical score per station, and based on the cut scores calculated for every station, average pass rate per analytical checklist grades in all stations was 70.4%, while average pass rate calculated for total scores in all stations was 79.2%. Four courses simulating professional skills of OSCE, two adapted undergraduate formative OSCEs, and a Medicinal Chemistry course, the control, correlated with the OSCE grades as follow, 0.72 (P < 0.01), 0.47 (P < 0.05), 0.43 (P>0.05), 0.65 (P < 0.01), 0.78 (P < 0.01), 0.61 (P < 0.01), and 0.36 (P>0.05) respectively. OSCE grades can be moderately predicted by Professional skills course grades (52.3%) and its practical assessment (61.2%). Average correlation between analytical and global grades for all assessors was 0.52. A total of 90% of the stations were deemed to reflect practice, according to student perceptions. The average ICC of analytical checklists scores, global scores, and total scores were 0.88 (0.71-0.95), 0.61 (0.19-0.82), and 0.75 (0.45-0.88) respectively. Cronbach's alpha of students' performance in global scores across stations was 0.87, and 0.93 in terms of total scores. Conclusion: The cumulative OSCE conducted in 2015 showed acceptable validity and reliability as a high stakes examination and therefore is suitable to be implemented as a mandatory core curriculum component for student pharmacist assessment in Qatar.
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Metal Organic Framework as a Potential Drug Carrier for Pulmonary Arterial Hypertension
Pulmonary arterial hypertension (PAH) is a progressive, debilitating and fatal condition [1]. Current PAH therapy relies on vasodilator drugs, which are seriously limited by their systemic side effects. We suggest that advances made in the field of nanomedicine could be used to improve the utility of drugs to treat PAH. Whilst not currently used clinically, metal organic frameworks (MOFs) such as the Material from Institute Lavoisier (MIL) class, are good candidates since (i) they can be tailored to accommodate different types of drugs including those with the molecular weights of PAH medications (MW; 300-500) [2], (ii) are biocompatible and biodegradable [3]; (iii) have a large internal surface area and low density with commensurate high drug loading capacity; (iv) are thermal and mechanically stable; and (v)have a long drug release period with the ability to incorporate different functional groups [2, 4-6]. However, the idea that nanomedicines can be used to treat PAH is very new and the use of MOFs in this regard is untested. Thus, we must first: (i) validate their chemical structure/stability, (ii) establish MOF cytotoxicity and effect on inflammatory responses in relevant cell types and (iii) investigate their behaviour in vivo model. In PAH, endothelial cells are critical cells to target. This is because the role of endothelial cells in releasing a delicate balance of vasoactive hormones is disrupted in PAH where cardioproective mediators such as nitric oxide and prostacyclin are reduced whilst the release of the constrictor peptide endothelin (ET)-1 is increased. Indeed, current PAH drugs work to boost nitric oxide and prostacyclin pathways and to block ET-1 receptor signalling. Aim: The aims of this work are to (i) synthesis and characterise MOFs designed to accommodate PAH drugs; (ii) to investigate the cytotoxic effect of MOFs in a comprehensive range of cell models relevant to PAH in vitro and the toxicity and distribution of MOFs in vivo. Methods: The nanoporous iron MOF (MIL-89), and a polyethylene glycol formulation (MIL-89 PEG) were prepared as previously described [2], then characterized using infrared spectroscopy (IR), powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). Endothelial cells grown from human blood progenitors of control subjects and PAH patients were cultured as we have done previously [7] and the effect of MOFs on viability determined using the AlamarBlue® Assay. In addition the effect of MOFs on endothelial cell inflammatory function was determined by measuring the release of the cytokine CXCL8 and on markers of PAH disease by measuring ET-1 using specific ELISAs. To investigate the effects of MOFs in vivo rats were injected with the MOF MIL-89 (50 mg/kg) in glucose solution twice a week for various times up to two weeks, while the control group was injected with glucose solution only. Animals were killed and tissues including; blood, heart, lung, brain, thymus, liver and kidney as well as urine and faeces were collected at days 1,3,7,10 and 14. Results: MIL-89 and MIL-89 PEG retained functional groups, and were crystalline, spherical and stable in air up to 200 °C. Neither preparations caused toxicity in cells grown from control donors or patients with PAH at concentrations up to 10 μg/ml (Fig. 1). Interestingly, both preparations of MOFs displayed anti-inflammatory effects; inhibiting CXCL8 and ET-1 release from endothelial cells from healthy donors as well as from PAH patients (Fig. 1). These MIL-89 had no affect on body weight of the rats and did not cause any gross changes in their lungs (Fig. 2). Conclusion: Both MIL-89 and MIL-89 PEG represent non-toxic potential drug-carriers with predicted molecular capacity for the current PAH medications, which include treprostinil sodium, bosentan and sildenafil. Furthermore, they both display some evidence of anti-inflammatory properties in vitro that may be of therapeutic benefit in the treatment of PAH. MIL-89 had no overt toxic effects in vivo, although these will need to be explored in more detail in future studies.
References
1. Archer, S.L., E.K. Weir, and M.R. Wilkins, Basic science of pulmonary arterial hypertension for clinicians: new concepts and experimental therapies. Circulation, 2010. 121(18): p. 2045-2066.
2. Horcajada, P., et al., Porous metal-organic-framework nanoscale carriers as a potential platform for drug delivery and imaging. Nat Mater, 2010. 9(2): p. 172-178.
3. Huxford, R.C., J. Della Rocca, and W. Lin, Metal-organic frameworks as potential drug carriers. Curr Opin Chem Biol, 2010. 14(2): p. 262-268.
4. Kızılel, S.K.a.S., Biomedical Applications of Metal Organic Framework, 2010, Department of Chemical and Biological Engineering: Koc- University, Rumelifeneri Yolu, 34450, Sarıyer, Istanbul, Turkey.
5. Ferey, G., et al., A chromium terephthalate-based solid with unusually large pore volumes and surface area. Science, 2005. 309(5743): p. 2040-2042.
6. Horcajada, P., et al., Metal-organic frameworks as efficient materials for drug delivery. Angew Chem Int Ed Engl, 2006. 45(36): p. 5974-5978.
7. Reed, D.M., et al., Morphology and vasoactive hormone profiles from endothelial cells derived from stem cells of different sources. Biochem Biophys Res Commun, 2014. 455(3-4): p. 172-177.
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Identification and Structural Analysis of Natural Product Inhibitors of Human Alpha-Amylase to Target Diabetes Mellitus
المؤلفون: Ameena Muhamed AliIntroduction: Noninsulin dependent diabetes mellitus (NIDDM) or Diabetes Type 2 is a major health challenge worldwide. In 2014 the World Health Organization (WHO) revealed that the percentage of adults with fasting glucose ≥ 7.0 mmol/L accounts for 9% globally. Moreover, the highest percentage was in the Eastern Mediterranean Region with 26.8 ± 0.4%. Type 2 diabetes is a complex metabolic disorder associated with high level of glucose in blood (hyperglycemia) which lead to long-term pathogenic conditions such as: neuropathy, retinopathy, nephropathy and a consequent decrease in quality of life and increased mortality rate.
Starch is the main source of energy for most living organisms; in humans it is digested over several stages that involve different amylolytic enzymes, such as α-Amylase and α-Glucosidase. Alpha Amylase is the major secretory product (about 5–6%) of the pancreas and salivary glands, playing a core role in starch and glycogen digestion. The control of postprandial hyperglycemia is an important strategy in the management of Type 2 diabetes; lifestyle modification and/or the use of medications such as insulin and α-Glucosidase inhibitors are the available treatments to date. Acrabose is a prominently used α-Glucosidase inhibitor for diabetes and obesity control, however it has many side effects and limitations. Numerous in vivo studies (REFS) have shown that many plant extracts inhibit the key enzymes of digestion (α-Amylase and α-Glucosidase) and the use of naturally occurring inhibitors is potentially the most effective and safest approaches for treating diabetes. Aims: Short-term aim: To clone, express and purify human α-Amylase protein using different yeast expression systems. Followed by protein (c0)crystallization and structural analysis.
Long-term aim: Screening natural products (plant extracts) based on their traditional use followed by co-crystallisation of selected inhibitors. This will be complemented by inhibitors designed in silico based on the ANCHOR.QUERY approach (REF). Finally, identified compounds will be characterised by biophysical and kinetic studies. Methodology: Human α-Amylase has been cloned into two vectors pHIPZ-4 and pPIC9k, each with its own set of primers, restriction enzymes and dedicated expression host (pHIPZ-4: Hansenula polymorpha and pPIC9k: Pichia pastoris, respectively). After transformation, the grown colonies were tested for the presence of the target gene by colony PCR and digestion with cloning enzymes. Positive colonies were re-inoculated in growth media and recombinant plasmid was recovered. The plasmids were then transformed into competent yeast cells by electroporation. For H. polymorpha, cells were grown in minimal media with glucose (MM/G) for two days followed by induction of expression with 0.5% (v/v) MeOH. Protein was purified by lysing the cells and passing the lysate through Ni-NTA beads. Finally protein was identified with by Western blot using HisProbe-HRP antibody. Results: Human α-Amylase gene was successfully cloned in both vectors pHIPZ-4 and pPIC9k according to colony PCR and digestion judgment on Agarose gel. However, the expression of α-Amylase protein in H. polymorpha system is insufficient to support the downstream work. Analysis of secreted expression using Pichia pastoris is currently underway and the results will be reported at the meeting. Conclusion: Human α-Amylase was successfully cloned in both vectors and stably transformed to E. coli competent cells. The positive colonies were confirmed for the present of targeted gene then transformed to yeast cells.
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Elucidating T7-like Bacteriophage Isolated from Qatar's Sand
المؤلفون: Aya AbdelaalA bacteriophage is a virus that infects a bacteria, it uses the bacteria as a host to further replicate by controlling the replication and protein synthesis machinery of the cell. They are composed of a protein capsule and DNA or RNA genome. Bacteriophages are used in the treatment of bacterial infections, known as the phage therapy. This results from phages invading the bacteria, as they undergo a lytic cycle, where the replication and protein synthesis machinery is used to produce virions, that later cause the cell to lyse, thus killing the bacteria. This technique has higher efficiency compared to the use of antibiotics as bacteria can develop a resistance against antibiotics, while remaining susceptible to the infection of the phage. In addition, phages can evolve and adapt to new mutations that might arise in the bacteria. Lastly, phages might be engineered to contain a survival gene needed by the bacteria to ensure that the bacteria will replicate and synthesize the new virons, leading to lysis and death.
This research explores the potential of the use of bacteriophages in the treatment of water, to disinfect the water from microbial bacterial and other bacteria that were used to detoxify the water. Phages were previously extracted from Qatar's sand and were used as the infecting agents. The model host chosen is Arthobacter bacteria, which is a denitrification bacteria, as it is similar to the bacteria used in water treatment. Denitrifying bacteria reduce nitrates to nitrogen-containing gases, allowing for the recycling of nitrogen back to the atmosphere.
The goal of my research is to analyze the genome of a phage extracted from Qatar's Sand. A culture of Arthobacter grown in Smeg media was used as a host. Unlike the normal optimal growth temperature of Arthobacter at 32 °C, it was shown that higher phage titer was produced when the culture was grown to saturation in smeg media at 37 °C. In addition, the culture was initially grown in luria Broth which is rich in nutrients including tryptone, yeast extract and NaCl. However, low phage titer was produced compared to switching the media to smeg media, which contains Middlebrook 7H9 broth base with supplements of albumin, dextrose and salts.
After manipulating the growth conditions of the host culture to obtain the highest titer, the optimum conditions were found to be a saturated culture of Arthobacter grown in Smeg media at 37 °C. Later, lysis conditions of the phage were optimized by varying several factors. First, the type of the top agar and plates used for pour plating were varied. Several top agars were used this includes LB top agar, LB top agar in 1 mM CaCl2 and PYCA top agar. It was concluded that the top agar that resulted in the highest titer was LB top agar in 1 mM CaCl2. Several plates have been used for pour plating this include LB plates and PYCA plates. Plaques formed using LB plates produced unclear plaques, this unclearness is an indication of persistence of the lysogenic state and not the lytic state. In the lysogenic state the phage genome gets incorportated into the host genome and replicates along with the cell cycle, thus remaining in a dormant state. On the other hand, in the lystic cycle, the phage uses the replication and protein synthesis machinery to produce more phages, that will later lead to lysis. In contrast, PYCA plates containing CaCl2 formed clearer plaques, indicating dominance of the lytic state. Therefore, addition of calcium in the top agar and the plates aided in the phages’ shift from the lysogenic cycle to the lytic cycle. This correlates with previous work, where calcium was shown to be essential for the penetration of the phage's genome into the host.
Finally, the incubation temperature of the plates containing the infected host Arthobacter by Qatar's sand's phage was varied. Initially the plates were incubated at 32 °C, however no plaques were formed. When the temperature was later increased to 37 °C, lysis was observed and a high phage titer was obtained.
After obtaining a high titer lysate, the DNA was isolated and a sample of the phage was sent to obtain an electron micrograph image of the phage. A restriction enzyme digest was preformed on the isolated DNA and the profile created was compared to the profile of lambda phage. Both the phages are lytic and lyse at similar temperatures, which allows for comparisons.
Lastly, motifs were identified between the Qatar's sand bacteriophage and T7 bacteriophage using blast tools in a previously extracted and sequenced Qatar's sand phage, primers will then be designed to verify if they exist in the actual phage.
Future work will focus on the analyzing the sequence of the phage to identify potential lysis genes, In addition, strengthening the lytic ability of the phage by cloning the gene of lysozyme into a T7-based vector system and test its adaptability to temperature using Arthrobacter as the host system.
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A Digitally Controlled Pseudo-Hysteretic Buck Converter for Low Power Biomedical Implants
المؤلفون: Paul Jung-Ho Lee, Amine Bermak and Man Kay LawBackground: Low power biomedical implants usually harvest energy from a small inductor coil or optical energy sources. Those sources can supply very limited amount of energy to the target system because of poor power transfer efficiency and size limitation. Thus, we have to supply as much as energy directly to the load, without wasting energy from auxiliary devices from electrical driving. To save the energy dissipated as heat, when the power supply voltage is excessively large compared to the voltage at the load, we can choose a class-H amplifier-like strategy, where supply voltage tracks the voltage waveform at the load. Among many power conversion topologies that can modulate the supply voltage, the SMPS (Switching Mode Power Supply) is the most promising one; because reverse energy recovery can be used by taking back the charge accumulated on the load capacitor. The CCM buck converter, shown in Fig. 1, can possibly work as a voltage tracking power supply modulator. However, we must employ a complicated auxiliary circuit components, such as the Type-III compensator, which greatly hampers its application for biomedical implant applications due to several external passive components. Proposed Power Converter: Therefore we propose a proposed digitally controlled hysteretic buck converter that is composed of 3 parts: power conversion, digital control, and pulse generation. Its controller can be implemented without bulky external passive components, but can quickly adapt the fast transient with a simple digital controller which incorporates just 1 comparator.
Figure 2 shows the power conversion part of the proposed buck converter. It is composed of power PMOS (W/L = 2 mm/0.5 μm), NMOS (W/L = 1 mm/0.5 μm), an active diode amplifier driving the NMOS, a 1 uH inductor, and a 1 uF capacitor. The power supply is 3.3 V. It adopts a typical buck converter configuration, where target switching frequency is 10 MHz. The NMOS active diode circuit is employed for minimizing the conduction loss across the NMOS body diode, when the energy stored in the inductor is released. The first stage of the active diode is common gate differential amplifier, of which the positive terminal is connected to GND and the negative input terminal is connected to the switching side of the inductor. The second stage of the active diode is common source amplifier stage, which serves to boost gain and increase the slew rate. Because it uses the negative feedback, the stability should be carefully checked. The simulated gain of the active diode was around 60 dB, with a 3 dB bandwidth of about 100 kHz.
In biomedical implant applications, the fast transient response is important, because the required power supply voltage can abruptly change, i.e. when an electrical stimulator changes the phase from anodic pulse to cathodic pulse. Thus, we propose a digital controller which can support such a fast transient response, which can make a voltage discursion of 1 V in less than 1 us. Figure 3 shows the proposed pseudo-hysteretic controller, for driving the power PMOS of the proposed power converter. It receives the reference voltage and the current output voltage as inputs, and then compares them. It asserts ‘1’ to report to the digital pulse generator (fsm_pulse_gen), when the reference voltage is higher than output voltage. The digital pulse generator increases the duty ratio when the comparator output is ‘1’, and decreases the duty ratio when the comparator output is ‘0’. The key of the control mechanism is binary weighted duty control. In this scheme, initially, the duty can jump by a predetermined maximum, being 16, and then, when the SMPS output approaches to the initial target voltage, the incremental amount decreased by half, being 8, and then again by half, being 4, and so on. The simulation result of the proposed power converter with the pseudo-hysteretic controller, which tracks reference voltage is shown in Fig. 4. In the beginning the converter operates in CCM, when the output voltage rapidly catch up the reference voltage; this is done by the digital controller which crank up the duty cycle to the maximum in a short period. Once the output supply voltage begins to be stabilized by crossing the reference voltage line, the converter changes the operation mode from CCM to DCM. Conclusion: We introduce a digitally controlled hysteretic buck converter with an active diode, intended for biomedical implant applications, featuring low-power consumption and fast transient response. For achieving these features, the associated digital controller employs the binary weighted duty update scheme, with overhead of a simple input processing comparator. An NMOS active diode can further decrease the wasted energy source by removing the loss that can be incurred from body diode conduction.
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Diabetes Awareness Among High School Students in Qatar
المؤلفون: Sara AmaniDiabetes is a disease that occurs when there is an abundance of glucose in the blood stream and the body cannot produce enough insulin in the pancreas to transfer the sugar from the blood to other areas in the body for energy. Type 1 and Type 2 diabetes are both prevalent in Qatar however, Type 2 diabetes is more common and it is mainly what is causing the epidemic Qatar is facing. Type 1 diabetes is inherited and is not related to eating habits or lifestyle, and it is diagnosed in juvenile years. However, Type 2 diabetes can be caused by obesity, unhealthy eating habits, and lack of exercise and overall fitness. It is treatable but not curable and can be treated by maintaining a healthy diet, regular exercise, insulin intakes, and oral medication.
Diabetes is the 3rd most common cause of death in Qatar after road accidents and heart disease (http://www.worldlifeexpectancy.com/country-health-profile/qatar). In fact, in 2011, Qatar ranked 6th for the highest percentage of diabetes in the world. The amount of overweight adolescents in Qatar is very large resulting in higher diabetes rates amongst children and young adults. The percentage of overweight children doubled from 17% in 1997 to 35% in 2007 according to The Peninsula newspaper. Awareness is crucial at this age because most of the human body fat is put on during teenage years when the body is constantly growing and it is very important to maintain a healthy weight at this time.
Students at the secondary school level should understand whether or not they are at risk of developing this disease compared to ordinary people. Each student should know their chances of risk due to their family relations, history, and habits. In Qatar we find that the parents of many students our age face diabetes because of the habits of their parents and so on, therefore all of us are at a higher risk. The fact that fast food is so available and practical keeps people, especially those at a young age constantly consuming such unhealthy products. With the statistics of obesity so alarmingly high, education and awareness is the only key to solving the problem. We plan on increasing the diabetic awareness at our school by conducting surveys, presenting posters, interviewing students, as well as working hand-in-hand with the Qatar Diabetes Association (QDA) to be as successful as possible.
Although many efforts are being made by the government, many students do not know enough about the danger that they may be putting themselves in, and the consequences that result because of their actions. Many students at this age are allowed to choose what they eat and their diets are not regulated by parents anymore, therefore they need to learn to make proper choices. The high temperatures in Qatar also make it inconvenient to exercise outside, however there are numerous alternatives. The goal of this research is to enlighten our peers with this given information and compare their knowledge of diabetes before and after. Awareness is the first step to prevention, and that needs to begin at a young age. Research Methods: The first step to our project on spreading awareness about diabetes is to know the level at which the students are already aware. Therefore, using Google Forums, we will create a survey with questions about how much the students already know about diabetes, if they know of family history, if they have been tested, if they know the symptoms, etc. Once we have fully created the survey, we will email the link to all of the high school students at our high school asking them to each fill out the survey with the appropriate responses. In order to insure that we have accurate gatherings, we will each interview an equal amount of students randomly and record their answers to work from there.
After receiving 189 responses from the high school students we began to analyze the results. Only 22% of the students had been tested for or against diabetes. Out of those who had been checked 48% had checked more than a year ago. 58% of the students knew of family members with diabetes. Most had checked the correct symptoms for diabetes along with a lot of unrelated ones like coughing or vomiting. Also for the things you could do to prevent diabetes, 8% responded with “washing your hands”, 30% responded with “not smoking”, and surprisingly even 3% responded with “dressing modestly”. After witnessing the high percentage of wrong responses, it was made clear that we definitely had to increase our effort in educating our peers.
Once discussing the open ended question of “What do you know about diabetes?” we ranked each student's response out of 10 (Based on the below scale). Then, we performed a chi-squared statistical test to compare our expected value of 7/10 to 3.323/10 which was the average student rank. This proved a significant difference between the levels of awareness we expected from the students, to what we actually received.
The data from the survey proved the indeed lack of awareness among the students of the high school level. We created fun awareness posters and posted them on glass doors to the cafeteria, science wing and specific lockers where they were most visible to the student population. Results and Discussion: Upon the completion of our presentation to the 10th grade health class, we conducted a second survey regarding what the students had learned and the quality of our presentation. The table below shows the responses received from the students after the presentation. Conclusions: Unfortunately at the beginning of this research, we were shocked at noticing the extreme lack of awareness amongst our student population. Considering the high rates of diabetes in the State of Qatar, we expected a basic understanding about the disease especially since many people here are prone to it. It is very alarming that which current trends it is expected that 73% of men and 69% of women would have reached obesity in the country by 2030. Indeed it can be stated that a lot of work needs to be done.
One of the major purposes of this research was to gain insight about this issue and it is quite obvious that these high rates are leading to a huge problem in the nation. Fortunately Qatar has been working hard to increase awareness with events like National Sports Day and hosting events like the 2022 world cup to promote fitness in the country. As mentioned previously, since diabetes type 2 is the major concern because it is developed later in life and is preventable, young students are the target for spreading information too. Habits develop during the adolescent years so spreading the word among students at this age is critical.
This research was very successful in promoting awareness in our own school, but from what we have learned, there is a long way to go in order to decrease the high statistical quantities of diabetes rates. Benefit to students: The Qatar National Research Strategy (QNRS) principle were designed to increase the quality of research occurring in Qatar. The third most important area of research in Qatar was health and under the Addressing National Health Priorities column, Type II diabetes was first in importance. We feel that by following the research plan addressed by H.H. Sheikha Moza that our research could have a strong impact on the research culture in Qatar indeed.
Some of the specific benefits to the students participating in this project include the following;
- How to conduct literature survey
- An increased knowledge and understanding about Diabetes, its causes, preventions and symptoms
- The seriousness of the issue worldwide and in Qatar
- The realization that the awareness of the students they spoke to increased so much that they can now give a lecture about the topic to their peers
- Presentation skills, video, poster, lecture
- Survey design
- How to conduct statistical analysis using statistical software
- Incorporating creative ways in educating their peers
- Communicating with professional societies such as Qatar Diabetes Association
- Took part in the joint program of Qatar Diabetes Association Sports Day event for the Action on Diabetes Campaign
- Interviewing skills as the asked questions of students and health care professionals working with diabetes
- Time management with creating a Letter of Intent and Proposal Report on time
- How to work as a team and how to divide the tasks to cover all requirements efficiently and effectively
- It is noteworthy to mention that the entire research methodology and the final report were fully prepared and conducted by the two students involved. The teacher's role was solely advisory
Qatar National Research Strategy (QNRS) mentions that diabetes is the 3rd most important area of research for QNRS.
Presenting the information about Diabetes to the high school student body, will not only benefit the students and teachers themselves in insuring their health and being aware of what may happen if they do not control some unnecessary desires, but it will inform them about the SSREP program in Qatar. As students participating in a research project during our secondary school years, presenting to our peers will allow them to realize the benefits that come from conducting research projects and inspire them to contribute in the following years.
Acknowledgement
Qatar National Research Fund – SSREP Program
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Is it the time for Hepatitis E virus (HEV) Testing for Blood Donors in Qatar?
المؤلفون: Gheyath Nasrallah, Laila Hedaya, Fatima Ali, Abdellatif Alhusaini, Enas Al Absi, Mariam Sami and Sara TalebBackground: HEV is the etiologic agent of acute hepatitis E. Although HEV usually causes a self-limiting infection, the disease may develop into a chronic or fulminant form of Hepatitis. Sporadic HEV infections spread in several developed countries; however, outbreaks usually occur in regions where sanitation is low, in particular, in developing countries where water flooding frequently occurs. In addition, religious background, life style, hygienic practices, and the economic status have been linked to HEV infection. Fecal-oral is the established route of transmission, however, infections through blood transfusion were recently documented in many developed and developing countries. This recent finding raises the question: is there is a need for HEV screening prior transfusion or transplantation? Studies related to this issue, in the Middle East are scarce. Although the CDC HEV epidemiological map, classifies the Arabian Gulf countries including Qatar as endemic or highly endemic, to the best of our knowledge, no HEV population –based epidemiological study were conducted in Qatar. HEV infection is usually detected using IgM and IgG serological tests and confirmed by molecular tests for detection of viral RNA. Yet, commercially available HEV serological kits are not validated, and needs further investigation. Aim and Methods: Qatar has a diverse population due to increased number of expatriate workers. The majority of these workers usually come from low economic status countries that are highly endemic for HEV such as Egypt, Sudan, India and other South East Asian countries. This fact highlights the need for an epidemiological study concerning HEV prevalence in Qatar. Accordingly, we hypothesize that HEV seroprevalence in Qatar is elevated, and therefore, there is a risk of HEV transfusion transmitted infections in Qatar's blood bank. The goals of this study are (i) to investigate the seroprevalence of HEV (anti-HEV IgM/IgG) among healthy blood donors in Qatar and (ii) to evaluate performance of 5 common commercially available anti-HEV IgG and IgM kits (manufactures by Wantai Biological Pharmacy, China; MP Biomedicals & Diagnostic Automation, USA; and Euroimmun & Mikrogen Diagnostik; Germany). All of these kits are solid phase ELISA based, except the Mikrogen kit which is immunoblot based. A total of 4056 blood donor samples were collected from healthy blood donors visited the Blood Donation Center at Hamad Medical Corporation (HMC) over a period of three years (2013-2015). For seroprevalence study, plasma were separated and tested for the presence of HEV IgG and IgM using Wantai ELISA kit, which, is the most commonly used serological kit according to literature. For statistical analysis, chi-square test was performed and results were considered statistically significant when the p-value were less than 0.05. Results: Out of total 4056 analyzed samples, almost one quarter of blood donors, 829 (20.45%) tested positive for anti-HEV IgG and only 21 (0.52%) blood samples tested positive for anti-HEV IgM. As shown in Fig. 1, HEV seroprevalence was associated with age group (P
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Antimicrobial and Cytotoxic Activity of Streptomyces sp. Isolated from Desert Soils, Qatar
المؤلفون: Sameera Shanawaz ShaikhStreptomyces are Gram positive aerobic bacteria from the phylum Actinobacteria with close to 570 known species. They are popular for providing a variety of compounds having medicinal properties including - antibiotics, antifungals, antitumor amongst others. Various researches in the past have tested these properties of Streptomyces sp. and species including Streptomyces avermitilis, Streptomyces venezuelae, Streptomyces aureofaciens, Streptomyces clavuligerns and Streptomyces erythrens have been found effective in producing these varied compounds. For instance, S. avermitilis produces avermectins which are used to treat river blindness while S. venezuelae secretes chloramphenicol. Additionally S. venezuelae has been suggested as ideal test organism for studies based on physiology and also for analysis of differentiation on biochemical basis (Chater, 2013). Although a high number of metabolites of Streptomyces are now available in the health care industry as effective drugs for a variety of diseases, increasing number of cases of antibiotic resistance is threatening global public health. The emergence of resistance has resulted in drug ineffectiveness and there is a wide search for suppressing these strains. Such resistance has been identified to have occurred due to both phenotypic and genotypic modifications (Suzuki, Horinouchi, & Furusawa, 2015). Properties of Streptomyces and increasing cases of antibiotic resistance have fuelled research to identify more and more species of Streptomyces and to look out for novel metabolites released from them. Other reasons for the need of identifying newer compounds include the breakout of new diseases in the second half of the last century, incompetence in fighting naturally resistant bacteria such as P.aerogenosa that causes fatal infections and the toxic effects resulting from consumption of currently available antibiotic drugs (Sanchez & Demain, 2011).
Hence this research attempted to study antimicrobial properties of three Streptomyces species isolated from the desert soil of Qatar. The antimicrobial properties were assessed firstly through direct testing against five test organisms - Escherichia coli and Pseudomonas sp. as Gram-negative bacteria, Candida albicans as fungi, Staphylococcus aureus and Streptococcus faecolis as Gram-positive bacteria. The three strains designated as sp. A, sp. B and sp. D exhibited good inhibition of the test organisms. Acetone, ethanol, ethyl acetate and methanol were used to prepare extracts of the three species and were used to re-assess antibacterial properties and also determine anticancer and antifungal properties. Antimicrobial properties were re-tested using disc-diffusion and puncture method while anticancer properties were studied by subjecting HCT-116 cancer cells to two different concentrations of extracts – 0.05%(v/v) and 0.5%(v/v). Acetone extracts showed some kind of inhibitory pattern hence a third concentration of 5%(v/v) was tested. Antifungal properties were examined by testing all extracts at 10%(v/v) against Aspergillus niger and Penicillium sp. Acetone extracts of all three species A,B and D displayed high inhibition of Aspergillus niger with 99.07% ± 0.12, 99.2% ± 0.01 and 99.19% ± 0.00 inhibition percentages respectively, and also inhibited growth of Penicillium sp. with 82.62% ± 1.62, 79.63% ± 0.11 and 87.44% ± 0.2 inhibition percentage respectively (% as compared to acetone control). These extracts were then re-tested at two other concentrations of 2.5%(v/v) and 5%(v/v). While the extracts at these concentrations were effective against Aspergillus niger, they could not inhibit growth of Penicillium sp.
References
Chater, K. F. (2013). Streptomyces. In S. M. Hughes (Ed.), Brenner's Encyclopedia of Genetics (Second Edition) (pp. 565–567). San Diego: Academic Press.
Sanchez, S., & Demain, A. L. (2011). 1.12 – Secondary Metabolites. In M. Moo-Young (Ed.), Comprehensive Biotechnology (Second Edition) (pp. 155–167). Burlington: Academic Press.
Suzuki, S., Horinouchi, T., & Furusawa, C. (2015). Suppression of antibiotic resistance acquisition by combined use of antibiotics. Journal of Bioscience and Bioengineering(0). doi: http://dx.doi.org/10.1016/j.jbiosc.2015.02.003
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A Close Look at the Genome and the Unbalanced Stratification of the Qatari Population
Microsatellites are segments of the DNA comprised of repeated sequences of 4 to 8-base pair units that are found throughout the genome of eukaryotes. Most microsatellites are located at non-coding regions of the genome and consequently mutations in the microsatellite regions are often not causatives of disease. This allows these regions to be highly polymorphic in a population and gives a signature DNA marker for each individual. At the same time, it is often expected to see a wide genetic diversity of alleles present in the populations. In humans, microsatellites, or short tandem repeats (STRs) are standard genetic markers used for human identification in forensic cases and parentage determination.
Databases of allele frequencies from various ethnic groups have been established in various parts of the world. In Qatar, as close-kin marriages are customary, homozygosity and possible reduced genetic variability have been a concern. A previous study, however, has concluded that the standard forensic markers are a valid tool for human identification because no substantive reduction of genetic variation has been observed as a result of consanguinity in the Qatari community.
In a more recent study, it has been determined that the Qatari population is subdivided into three main ethnic groups, of Bedouin, African or Persian ancestry. This segregation has been genetically significant through studies in single nucleotide polymorphism, or SNP studies. Since SNPs and microsatellite DNA are inherited in a similar fashion, it is expected that there are different allele frequencies for assessed microsatellite loci for each of the populations. Moreover, the allelic heterogeneity in a population is closely linked to interbreeding. Since the Qatari Bedouin population has been closely associated with the practice of consanguinity as evidenced through SNP studies, it is therefore also expected to see higher homozygosity in the Bedouin subpopulation as compared to the other two subpopulations.
In recent years diabetes occurrences in the Qatari populations have reached an epidemic level. Like many other diseases where both lifestyle as well as genetics may play a role in the onset of this disease, the microsatellite loci may serve as markers genetically linked to some of the non-communicable disease such as diabetes.
The main aim of this study is to understand the genetic variability across the subpopulations of the Qatari nationals. The result can be used to develop new forms of personalized health care that is specific to members of the stratified Qatari subpopulations. The information allows for more efficient treatments and better management to the growing Qatari populations. To accomplish these goals, blood samples are collected from 300 individuals, with 100 from each subpopulation. AmpFISTR® Identifiler® Plus PCR Amplification Kit is used for a multiplex analysis of 15 tetranucleotide loci. The resulting data are analyzed to produce allele frequencies of each of the loci for the corresponding subpopulations. The gene diversity within and among the subpopulations are analyzed and the detection of consanguinity through the application of Hardy-Weinberg is discussed. The sub-profiles for each of the three Qatari subpopulations – Bedouin, African and Persian – are presented. Finally, the concept of personalized health care with respect to diabetes is introduced and the clinical applications relevant to the populations are discussed.
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Reflex System for Intelligent Robotics
المؤلفون: Ahmad Yaser Alhaddad and John-John CabibihanBackground and Purpose: Great advances have occurred in the field of robotics in the past few years. The integration of robotics in our daily life became not only limited to manufacturing or industrial usage, but also in health care delivery, aerospace, humanitarian aids and others. Most of the existing robots systems rely on the programmer to set the rule it plays within the working environment or rely on a trainer to teach the system what should and need to be done and where they are ought to move. Other robotic systems might involve more intelligent systems to explore and handle tasks within their environment. Most of these systems are usually situated to work within well organized and planned environment. Having modifications on any of the parameters of the environment might produce unpredictable consequences. Depending on the complexity of the system and how intelligent it is, the consequences might be unfavorable in achieving the goals intended and reducing oneself-damages.
Species in nature represents rich source of innovative ideas and creative concepts that can be investigated by researchers. Nature has been inspiring scientists into developing new ways of looking at things, by observing the various living organisms' behaviors in their own habitats. Behavior-based roboticists are concerned with the development of robots based on observing and the studying of neuroscience, psychology and ethology of animals in nature. Humans, animals and plants physiology is yet another rich source of researching potential (Fig. 1). For example, reflexes in living organisms represent a means of survival in the outer environment and means of regulating internal body operations. If we could observe and try to mimic some of the reflex behaviors, we could end up with a machine (E.g. Robots) that has the ability to avoid dangerous situations and keep the outer structure intact.
Figure 1: The potential of reflex systems in intelligent robotics. Objective: Adopting an intelligent reflex system in the robot system similar to that found in humans, animals, and plants can have significant advantages on the overall behavior of the system. A reflex system can improve the risk avoiding capabilities in the unfavorable scenarios. Design: The approach toward reflex based robotic system involves the intensive investigation and review of the fundamental concepts found in the reflex systems of human, animals, and plants. Attention to details, such as the behavior of the organism when subjected to a certain stimulus and the latency it takes for the reflex arc to execute the right response, are among the most important things to consider when trying mimicking the behavior of a living organism. A deduced conceptual model should be based on the distinguishing components found in the reflex arc. An actual design based on this proposed model, will include the basic components that can be achieved by using electronic/mechanical components that are at the same time analogous in function to the ones found in the reflex arc. For example, to mimic the temperature sensing capabilities of a human hand, a simple one-point temperature sensor will not be sufficient to give a desirable realistic result. Instead, a sophisticated flexible array that is capable to sense the temperature at any point must be used. Another design consideration is the controlling method to be used. Will it be centralized or decentralized or a mix of both? Regardless of the answer the controlling mechanism involved should be independent of a central controller (i.e. the brain) and it must be localized to achieve the desirable fast response as that founded in the reflex arc. Conclusion: The reflex based robotic system will be unique and innovative for the applications intended. The system can be incorporated with pre-existing systems to add value especially in the field of medical robotics and more specifically in prosthetics. Artificial reflex systems will add great value, protective feature and life-like sensation for a smarter prosthetic artefacts. With the implementation of the reflex arc at the right latencies and order, the gap between artificial and the actual hand should get narrower.
Acknowledgment
This publication was made possible by the support of an NPRP grant from the Qatar National Research Fund (NPRP 7-673-2-251). The statements made herein are solely the responsibility of the authors.
Keywords
Intelligent Robotics, Reflex System, Prosthetics
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Preparation and Characterization of Letrozole-Loaded Poly (D,L-Lactide) Nanoparticles for Breast Cancer Therapy
المؤلفون: Bayan Alemrayat, Abdelbary Elhissi and Husam YounesIntroduction: Breast cancer has been ranked first as the most prevalent type of cancer and the leading cause of cancer-related mortality among women worldwide. Letrozole (LTZ), an aromatase inhibitor, has been shown to be an effective and relatively safe agent for the treatment of hormonally-positive breast cancer in postmenopausal women. However, the drug suffers from poor water solubility and rapid metabolism, leading to low oral bioavailability, and thus, lower anticancer effects at target sites. Interestingly, polymer-based nanoparticles (NPs) have been reported to be effective drug delivery systems as integrating drugs into these carriers have presented substantial improvements in drugs tissue distribution and tissue selectivity with superior pharmacokinetic profiles. Therefore, this study was designed to incorporate LTZ into an FDA approved polymer; poly (D,L-Lactide) (PDLLA) nanoparticles to improve its physiochemical properties and bioavailability. Methods: Emulsion-solvent evaporation technique was used to produce LTZ-PDLLA NPs. Briefly, 250 mg PDLLA was mixed with different w/w ratios of LTZ (10-30%) in 20 ml dichloromethane. The prepared solution was slowly poured via a syringe into an aqueous phase (140 ml) to form an emulsion which was followed by a two-step sonication. The emulsion was sonicated using Branson® B5510 ultrasonic cleaner at 40 KHz frequency for 30 minutes, vortexed for 2 minutes, then sonicated again for another 30 minutes. Solvent was allowed to evaporate completely by stirring for 2 hours at room temperature. The resultant dispersed particles were centrifuged at 8500 rpm, 5 °C for 2 hours. Supernatant was discarded and the pellet comprising the NPs was dried under vacuum over 48 hours. The obtained NPs were characterized using Scanning Electron Microscope (SEM), Zetasizer, Differential Scanning Calorimeter (DSC), X-Ray Diffractometer (XRD), & Ultra Performance Liquid Chromatography (UPLC). Results: LTZ-PDLLA nanoparticles were prepared with a high yield that reached 85%. The NPs were spherical in shape with smooth surfaces across all LTZ loadings. An increase was seen in particle size from 242 nm to 365 nm upon increasing LTZ concentration from 0% to 30% w/w. Such finding was expected since larger contents of LTZ would definitely contribute to the increase in the diameter of the enclosing polymer. Particles were polydisperse in general with a polydispersity index (PDI) ranging from 0.38 to 0.44 and this was mainly due to the fact that non-uniform force was applied to each droplet injected into the aqueous medium while producing the emulsion. DSC and XRD analyses confirmed the crystalline nature of LTZ that was lost after being incorporated into the amorphous polymer, PDLLA. This will have a great impact on the dissolution rate and later on the release rate from PDLLA in which amorphous particles tend to be released easily and in a more controlled fashion than crystalline counterparts. The actual content of LTZ loaded inside PDLLA was expressed as entrapment efficiency and calculated via UPLC analysis through subtracting the amount of LTZ present in the supernatant from the initial amount of LTZ added in each formulation. Very high entrapment efficiency was obtained with all formulations ranging from 87.9% with 10% LTZ-PDLLA up to 96.7% with 30% LTZ-PDLLA. As such, high concentrations of LTZ can be delivered to the target sites with minimum drug loadings. Conclusion: LTZ-PDLLA nanoparticles were successfully prepared with high entrapment efficiency using emulsion-solvent evaporation technique. The physiochemical properties and entrapment efficiency were dependent on LTZ concentration. Future work should focus on reducing the wide size distribution by formulating monodisperse particles which would allow uniform tissue distribution and longer sustained release actions upon administration. Additionally, in-vitro testing is needed to evaluate the efficacy and safety of the new formulations.
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Favoring Inhibitory Synaptic Drive Mediated by Gabaa Receptors in the Basolateral Nucleus of the Amygdala Efficiently Reduces Pain Symptoms in Neuropathic Mice
المؤلفون: Kamoun NisrinePain is an emotion and neuropathic pain symptoms are modulated by supraspinal structures such as the amygdala. If the central nucleus of the amygdala is often named as the “nociceptive amygdala”, little is known on the role of the basolateral amygdala. Here, we monitored the mechanical nociceptive thresholds of in a mouse model of neuropathic pain and infused modulators of the glutamate/GABAergic transmission in the BLA via chronically-implanted can nulas. First, we found that NMDA-type glutamate receptor antagonist (MK-801) exerted a potent anti-allodynic effect whereas a transient allodynia was induced after perfusion of bicuculline, a GABAA receptor antagonist. Potentiating GABAA receptor function using diazepam (DZP) or etifoxine (EFX, a nonbenzodiazepine anxiolytic) fully but transiently alleviated mechanical allodynia. Interestingly, the anti-allodynic effect of EFX disappeared in animals incapable of producing 3alpha-steroids. DZP had a similar effect but of shorter duration. As indicated by patch-clamp recordings of BLA neurons, these effects were mediated by a potentiation of GABAA R-mediated synaptic transmission. Together with a presynaptic elevation of miniature IPSC frequency, the duration and amplitude of GABAA mIPSCs was also increased (postsynaptic effect). The analgesic contribution of endogenous neurosteroid seemed to be exclusively postsynaptic. This study highlights the importance of BLA and of the local inhibitory/excitatory neuronal network activity while setting the mechanical nociceptive threshold. Furthermore, it appears that promoting inhibition in this specific nucleus could fully alleviate pain symptoms. Therefore BLA could be a novel interesting target to develop pharmacological or non pharmacological therapies.
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