Embryonic stem cells are conventionally differentiated by modulating specific growth factors in the cell culture media. Recently the effect of cellular mechanical microenvironment in inducing phenotype specific differentiation has attracted considerable attention. We have shown the possibility of inducing endoderm differentiation by culturing the stem cells on fibrin substrates of specific stiffness [1]. Here, we analyze the regulatory network involved in such mechanically induced endoderm differentiation under two different experimental configurations of 2-dimensional and 3-dimensional culture, respectively. Mouse embryonic stem cells are differentiated on an array of substrates of varying mechanical properties and analyzed for relevant endoderm markers. The experimental data set is further analyzed for identification of co-regulated transcription factors across different substrate conditions using the technique of bi-clustering. Overlapped bi-clusters are identified following an optimization formulation, which is solved using an evolutionary algorithm. While typically such analysis is performed at the mean value of expression data across experimental repeats, the variability of stem cell systems reduces the confidence on such analysis of mean data. Bootstrapping technique is thus integrated with the bi-clustering algorithm to determine sets of robust bi-clusters, which is found to differ significantly from corresponding bi-clusters at the mean data value. Analysis of robust bi-clusters reveals an overall similar network interaction as has been reported for chemically induced endoderm or endodermal organs but with differences in patterning between 2-dimensional and 3-dimensional culture. Such analysis sheds light on the pathway of stem cell differentiation indicating the prospect of the two culture configurations for further maturation.

Embryonic stem cells (ESC) have two main characteristics: they can be indefinitely propagated in vitro in an undifferentiated state and they are pluripotent, thus having the potential to differentiate into multiple lineages. Such properties make ESCs extremely attractive for cell based therapy and regenerative treatment applications (1). However for its full potential to be realized the cells have to be differentiated into mature and functional phenotypes, which is a daunting task. A promising approach in inducing cellular differentiation is to closely mimic the path of organogenesis in the in vitro setting. Pancreatic development is known to occur in specific stages (2), starting with endoderm, which can develop into several organs, including liver and pancreas. Endoderm induction can be achieved by modulation of the nodal pathway through addition of Activin A (3) in combination with several growth factors (4-7). Definitive endoderm cells then undergo pancreatic commitment by inhibition of sonic hedgehog inhibition, which can be achieved in vitro by addition of cyclopamine (8). Pancreatic maturation is mediated by several parallel events including inhibition of notch signaling; aggregation of pancreatic progenitors into 3-dimentional clusters; induction of vascularization; to name a few. By far the most successful in vitro maturation of ESC derived pancreatic progenitor cells have been achieved through inhibition of notch signaling by DAPT supplementation (9). Although successful, this results in low yield of the mature phenotype with reduced functionality. A less studied area is the effect of endothelial cell signaling in pancreatic maturation, which is increasingly being appreciated as an important contributing factor in in-vivo pancreatic islet maturation (10,11). The current study explores such effect of endothelial cell signaling in maturation of human ESC derived pancreatic progenitor cells into insulin producing islet-like cells. We report a multi-stage directed differentiation protocol where the human ESCs are first induced towards endoderm by Activin A along with inhibition of PI3K pathway. Pancreatic specification of endoderm cells is achieved by inhibition of sonic hedgehog signaling by Cyclopamine along with retinoid induction by addition of Retinoic Acid. The final stage of maturation is induced by endothelial cell signaling achieved by a co-culture configuration. While several endothelial cells have been tested in the co-culture, herein we present our data with rat heart microvascular endothelial Cells (RHMVEC), primarily for the ease of analysis.

BACKGROUND Routes of transmission of hepatitis B virus (HBV)/HIV infections are similar and there is a significant rate of co-infection in patients. A study was recently carried out in NHS Fife, Scotland from February 2007 - February 2008 to estimate the prevalence of HBV/HIV co-infection, occult HBV infection and immunisation status against HBV in a cohort of patients with HIV attending the departments of infectious diseases and genitourinary medicine. METHODS Case notes were reviewed retrospectively (n = 70). Details on patient demographics, risk category, nadir/current CD4 count, HIV viral load and vaccination history were analysed. HBV markers (HBsAg/anti-HBs/anti-HBc/HBV DNA) and alanine transaminase (ALT) levels were tested prospectively if these tests had not been carried out in the previous 12 months. RESULTS AND CONCLUSION Prevalence of HBV/HIV co-infection was 5.6% of which 2.8% of patients had occult infection and 22.9% had evidence of previous exposure. Although HBV is preventable by vaccination, only 24.2% of patients had been vaccinated against it. Improvements could therefore be made in the field of prevention with vaccination and monitoring the immune response in this cohort. KEYWORDS: Prevalence; Immunization status; Hepatitis B Virus; HIV.

Ellagic acid (EA), a plant polyphenol known for its wide-range of health benefits was encapsulated within self-assembled threonine based peptide microtubes. The microtubes were assembled using the synthesized precursor bolaamphiphile bis(N-α-amido threonine)-1,5-pentane dicarboxylate. The self-assembly of the microstructures was probed at varying pH. In general, tubular formations were observed at a pH range of 4-6. The formed microtubes were then utilized for fabrication with EA. We probed the ability of the microtubes as drug release vehicles for EA as well as for antibacterial applications. It was found that the release of EA was both pH and concentration dependent. The biocompatibility as well as cytotoxicity of the EA-fabricated microtubes was examined in the presence of mammalian normal rat kidney (NRK) cells. Finally the antibacterial effects of the EA incorporated peptide microtubes was examined against Escherichia coli and Staphylococcus aureus.

BACKGROUND Organophosphorus (OP) poisoning is a major health problem all over the world, particularly in the developing countries. AIM The present study aims to explore the clinical and epidemiological features found in patients presenting with OP poisoning. MATERIALS AND METHODS A 1-year cross-sectional study was conducted on patients presenting with clinical features of OP poisoning in a tertiary care medical college. RESULTS A total of 968 patients presented during the study period. Poisoning with suicidal intent (82.02%) was more common than the accidental one (17.98%). Majority of the patients were housewives (42%) followed by farmers, shopkeepers, laborers, students. Methyl parathion was the most common poison consumed by the patients (35.74%) followed by diazinon, chlorpyriphos, dimicron. Nausea and vomiting (85.02%) was the most common symptom while miosis was the most common sign observed in 91.94% patients. A total of 56 patients of OP poisoning died (5.78%) with respiratory failure being the primary cause of death followed by CNS depression, cardiac arrest, and septicaemia. CONCLUSION The present study showed that majority of the patients were of young age with females outnumbering males. Poisoning with suicidal intent was more common than accidental. Nausea and vomiting was the most common symptom reported by the patients while miosis was the most common sign observed by the treating physicians of the research team.

The mechanisms by which human embryonic stem cells (hESC) differentiate to endodermal lineage have not been extensively studied. Mathematical models can aid in the identification of mechanistic information. In this work we use a population-based modeling approach to understand the mechanism of endoderm induction in hESC, performed experimentally with exposure to Activin A and Activin A supplemented with growth factors (basic fibroblast growth factor (FGF2) and bone morphogenetic protein 4 (BMP4)). The differentiating cell population is analyzed daily for cellular growth, cell death, and expression of the endoderm proteins Sox17 and CXCR4. The stochastic model starts with a population of undifferentiated cells, wherefrom it evolves in time by assigning each cell a propensity to proliferate, die and differentiate using certain user defined rules. Twelve alternate mechanisms which might describe the observed dynamics were simulated, and an ensemble parameter estimation was performed on each mechanism. A comparison of the quality of agreement of experimental data with simulations for several competing mechanisms led to the identification of one which adequately describes the observed dynamics under both induction conditions. The results indicate that hESC commitment to endoderm occurs through an intermediate mesendoderm germ layer which further differentiates into mesoderm and endoderm, and that during induction proliferation of the endoderm germ layer is promoted. Furthermore, our model suggests that CXCR4 is expressed in mesendoderm and endoderm, but is not expressed in mesoderm. Comparison between the two induction conditions indicates that supplementing FGF2 and BMP4 to Activin A enhances the kinetics of differentiation than Activin A alone. This mechanistic information can aid in the derivation of functional, mature cells from their progenitors. While applied to initial endoderm commitment of hESC, the model is general enough to be applicable either to a system of adult stem cells or later stages of ESC differentiation.

OBJECTIVE: Although significant research has detailed angiogenesis during development and cancer, little is known about cardiac angiogenesis, yet it is critical for survival following pathological insult. The transcription factor c-Myc is a target of anticancer therapies because of its mitogenic and proangiogenic induction. In the current study, we investigate its role in cardiac angiogenesis in a cell-dependent and gene-specific context. METHODS AND RESULTS: Angiogenesis assays using c-Myc-deficient cardiac endothelial cells and fibroblasts demonstrate that c-Myc is essential to vessel formation, and fibroblast-mediated vessel formation is dependent on c-Myc expression in fibroblasts. Gene analyses revealed that c-Myc-mediated gene expression is unique in cardiac angiogenesis and varies in a cell-dependent manner. In vitro 3-dimensional cultures demonstrated c-Myc's role in the expression of secreted angiogenic factors, while also providing evidence for c-Myc-mediated cell-cell interactions. Additional in vivo vascular analyses support c-Myc's critical role in capillary formation and vessel patterning during development and also in response to a pathological stimulus where its expression in myocytes is required for angiogenic remodeling. CONCLUSIONS: These data demonstrate that proper c-Myc expression in cardiac fibroblasts and myocytes is essential to cardiac angiogenesis. These results have the potential for novel therapeutic applications involving the angiogenic response during cardiac remodeling.

Porphyrins have been used for photodynamic therapy (PDT) against a wide range of targets like bacteria, viruses and tumor cells. In this work, we report porphyrin-conjugated multi-walled carbon nanotubes (NT-P) as potent antiviral agents. Specifically, we used Protoporphyrin IX (PPIX), which we attached to acid-functionalized multi-walled carbon nanotubes (MWNTs). We decided to use carbon nanotubes as scaffolds because of their ease of recovery from a solution through filtration. In the presence of visible light, NT-P was found to significantly reduce the ability of Influenza A virus to infect mammalian cells. NT-P may be used effectively against influenza viruses with little or no chance of them developing resistance to the treatment. Furthermore, NT-P can be easily recovered through filtration which offers a facile strategy to reuse the active porphyrin moiety to its fullest extent. Thus NT-P conjugates represent a new approach for preparing ex vivo reusable antiviral agents.

The use of computer and information technology is on an escalation. The internet, one of the key developments in this field, provides instant access to latest medical information. The present study was conducted (i) to estimate the extent and purpose of internet usage among undergraduate (UG) and postgraduate (PG) medical students,(ii) to identify factors that encourage the students to use internet for medical information,(iii) to assess the need for incorporating computer education in medical curriculum. A prospective, cross-sectional, questionnaire-based study was conducted on 150 students of Burdwan Medical College and Hospital between June 2009 and December 2009. Majority of the students accessed internet from their home PC (42% UGs and 52% PGs).Common search engines browsed commonly by both UGs and PGs include Google and yahoo. Regarding principles of telemedicine and evidence-based medicine, majority of the PGs are well versed while UGs are not (p-value 0.0001). Almost all students agreed to incorporate computer education in medical curriculum. Primary source of medical information was textbook for UGs (62%) and internet for the PGs (48%). Majority of UGs (48%) used internet as a ready source of information thus saving time while PGs (68%) primarily relied on internet for recent advances in their disciplines. The primary purposes of internet use are educational for both UGs and PGs. The data obtained indicates that majority of the medical students participating in the present study embrace and use internet to access medical information. It also justifies the need to incorporate internet and associated information technology into existing medical curriculum.

Type 1 diabetes affects more than a million people in the United States and many more across the world. While pharmaceutical interventions and insulin supplementation are the most commonplace treatment of diabetes, these are not essentially cures and can potentially lead to long-term complications. Transplantation of insulin-producing Islets of Langerhans from donor pancreas has been established as a promising alternative to diabetes therapy. While successful islet transplantation has the potential of providing a cure, the primary hurdles to be overcome for it to be clinically viable are the scarcity of donor islets and immune rejection of transplanted islets. Recent advances in stem cell culture and differentiation techniques have established stem cells as a likely source of transplantable islets. Different stem cell sources have been induced toward pancreatic differentiation using specific chemical perturbations along with use of specific substrates. An approach to overcoming the second hurdle of immune rejection of transplantable islets is to encapsulate the islets in specific biomaterials. In this review, we discuss the extensive use of various substrates for pancreatic differentiation of different stem cell sources, along with different biomaterial designs used for islet transplantation.