Publications by authors named "Vijayalakshmi Venkateshan"

Glaucoma is the second leading cause of blindness. Exfoliation syndrome (XFN) is a risk factor for exfoliation glaucoma (XFG) which is a secondary open angle glaucoma. XFG is difficult to manage with a worse prognosis. Though 40% of the XFN progress to XFG, there are no predictive markers to identify the susceptible patients. Herein, we analyze clinical data, ATP levels in aqueous humor and cytokines in plasma to identify alteration that help distinguish XFN from XFG. Our results show characteristic clinical features of XFG compared to XFN and controls. Elevated levels of ATP in aqueous humor were observed in XFG compared to XFN and cataract controls while elevated levels of plasma cytokines were observed in XFG compared to XFN, cataract controls and healthy controls. Microglia are immune cells in the retina implicated in glaucoma. TNFα plays a predominant role in microglial inflammation and is implicated in neurodegeneration. Using in vitro N9 microglial cell culture model, we demonstrate that TNFα modulated expression of cytokines and chemotaxis is dependent on P2 receptors like P2X, P2Y and P2Y. In addition, ATP also induce expression of TNFα which might act as a feed forward loop. The TNFα induced inflammation is dependent on downstream signaling modules like PI3K, JNK and ROS. Taken together, our results show that elevated ATP in aqueous humor, plasma cytokines and inflammation potentially involving microglia distinguish XFG from XFN. Purinergic receptors might be potential therapeutic targets in XFG.

Ethnopharmacological Relevance: Aloe vera (L.) Burm. f. extract has been medicinally used for over 5000 years in different cultures for its curative and therapeutic properties ranging from dermatitis to diabetes. It has been demonstrated to alleviate diabetes through its protective effects on pancreatic islets and by improving insulin secretion.

Aim Of The Study: To investigate the simultaneous effect of ethanolic A. vera gel extract on diabetes and obesogenic milieu in Streptozotocin-induced WNIN/GR-Ob mutant obese rats.

Materials And Methods: A total of 30 rats were grouped equally into WNIN/GR-Ob control (received water as a vehicle), WNIN/GR-Ob Diabetic rats (Streptozotocin-35 mg/kg bw), WNIN/GR-Ob Diabetic rats + Sitagliptin (10 mg/kg bw), WNIN/GR-Ob Diabetic rats + A. vera (300 mg/kg bw) and GR-Ob control + A. vera (300 mg/kg bw). After 4 weeks of treatment, fasting blood glucose, serum insulin, Homeostatic Model Assessment - Insulin Resistance and β-cell function, glucose-stimulated insulin secretion, Dipeptidyl peptidase-IV activity, and lipid profiles were studied. In addition, ultrastructural analysis of isolated islets and dual-energy X-ray absorptiometry analysis for body composition were also carried out.

Results: The A. vera treated group showed a significant reduction (p < 0.05) in triglyceride, Very low-density lipoprotein levels, Triglyceride to High-density lipoprotein ratio as well as fasting blood glucose levels and DPP-IV activity with a concomitant increase in the serum insulin levels. The increase in IR was observed in both WNIN/GR-Ob control and diabetic rats with a significant decrease in β-cell function in the diabetic rats as per Homeostatic Model Assessment values. Oral administration of A. vera was effective in both reducing Homeostatic Model Assessment-Insulin Resistance and increasing Homeostatic Model Assessment-β values. Also, the treated group demonstrated preservation of islets and a significant increase (p < 0.05) in the diameter of β-cell as evident through Scanning electron microscope analysis. The increase in lean body mass was manifested in the treated group with a reduction in Fat percent in comparison with other groups.

Conclusion: The beneficial effects of A. vera in WNIN/GR-Ob strain may be attributed to its ability to lower lipid profile thus improve insulin sensitivity and/or modulating β-cell function. Thus, it has great therapeutic potential as an herbal remedy for the treatment of diabetes and associated adverse effects such as obesity. The exact mechanism underlying the observation needs to be investigated further to explore the anti-obesity and anti-diabetic properties of A. vera and advocate its potential application as alternative medicine.

Background: Coronary artery disease (CAD) is the leading cause of death and disability worldwide. Lipoprotein associated phospholipase A (Lp-PLA) is an emerging biomarker for inflammation that has shown association with CAD. Its significance in the Asian Indian population is not clearly known. We sought to compare the possible association of various biomarkers of atherosclerosis along with Lp-PLA, in symptomatic individuals with CAD vs. healthy controls in Asian South-Indians.

Methods: We conducted a cross-sectional case control study at three centers in a South Indian population. A total of 100 CAD patients with acute coronary syndrome (ACS), 100 age and gender matched healthy controls participated, of which, 166 subjects or 83 case-control pairs with complete data for both participants were identified for the statistical analysis. Lp-PLA concentration and activity were measured using PLAC test and PLAC activity assay respectively (diaDexus Inc., San Francisco, CA, USA), while all other parameters were measured using standard commercially available kits.

Results: We enrolled a total of 200 subjects (mean age 50.7±9.6 years, 87.5% males). A total of 83 subjects completed the study in the CAD group (mean age 51 ±8.9 years, 85% males) and 83 subjects in the control group (mean age 50±8.9 years, 86.5% males). In the CAD group, Lp-PLA concentration positively correlated with TC (ρ=0.19, P=0.02), non-HDL-C (ρ=0.20, P=0.02), Lp-PLA activity (ρ=0.27, P=0.001) and Lp(a) (r=0.25, P=0.02). Lp-PLA activity correlated positively with TC (ρ=0.28, P=0.001), LDL-C (ρ=0.30, P<0.001), non-HDL-C (ρ=0.35, P<0.001), ApoB (ρ=0.35, P<0.001) and negatively correlated to HDL-C (ρ=-0.24, P=0.004). Cox proportionality hazards model revealed Lp-PLA concentration (β=0.006, SE =0.002, P=0.009) to have positive association with the event of CAD, while negative association was observed for ApoA1 (β=-0.06, SE =0.02, P=0.001). ROC analysis revealed that the highest quartile of Lp-PLA concentration to have area under curve (AUC) of 0.80 (95% CI, 0.65-0.9; P<0.001) with cut off value of >427 ng/mL and ApoA1 with AUC of 0.78 (95% CI, 0.70-0.85; P<0.001) with cut off value of ≤129.6 mg/dL with the optimum balance of sensitivity and specificity.

Conclusions: In this study population, circulating plasma Lp-PLA was found to be elevated in CAD group. ApoA1 showed negative association and Lp-PLA concentration showed positive association with risk for CAD. In the highest quartile, Lp-PLA concentration had the best diagnostic utility. Our results support the hypothesis that Lp-PLA may be a potential risk marker for CAD in Asian Indians.

Background: Long-term survival and functions of encapsulated islet grafts need to be evaluated in the absence of immunosuppression. The present study aimed to assess the viability and functions of macroencapsulated islets grafted in nonhuman primates without immunosuppression for 1 year.

Methods: Islet transplantations were performed in partially pancreatectomized rhesus monkeys (two autologous and four allogenic) without immunosuppression using immunoisolatory devices. Macroencapsulated islets were implanted subcutaneously (5000-8000 IEQ/device) at two sites (left thigh and interscapular region) and were explanted at 2, 6, and 12 months after implantation. Staining for viability and apoptosis, in vivo and in vitro glucose-stimulated insulin release, expression of insulin and glucagon genes, and histopathologic examination of the device were used to assess engraftment potential, viability, and functions of islets. Animals were regularly monitored for dietary intake, body weight, and fasting blood glucose levels after islet transplantation.

Results: Devices explanted showed vascularization at the end of 2, 6, and 12 months with occasional lymphocytes and minimal fibrosis outside the device. Flow cytometric analysis revealed 97.9%±1.5% and 94.3%±5.71% viable β cells in interscapular site and thigh in autologous recipients and 85.6%±4.01% (interscapular site) and 74.1%±12.05% (thigh) viable β cells in allogenic islet recipients. In vivo glucose challenge test revealed significantly increased glucose-stimulated insulin release (P=0.028) in the left thigh with implant (17.58±3.13 mU/L) compared with the thigh without implant (9.86±1.063 mU/L). Insulin and glucagon gene expression was evident in islets recovered from explanted device.

Conclusions: These results indicate that subcutaneous implantation of macroencapsulated islets is minimally invasive and has potential for transplantation without immunosuppression.

Fetal calf serum (FCS) is conventionally used for animal cell cultures due to its inherent growth-promoting activities. However animal welfare issues and stringent requirements for human transplantation studies demand a suitable alternative for FCS. With this view, we studied the effect of FCS, human AB serum (ABS), and human umbilical cord blood serum (UCBS) on murine islets of Langerhans and human bone marrow-derived mesenchymal-like cells (hBMCs). We found that there was no difference in morphology and functionality of mouse islets cultured in any of these three different serum supplements as indicated by insulin immunostaining. A comparative analysis of hBMCs maintained in each of these three different serum supplements demonstrated that UCBS supplemented media better supported proliferation of hBMCs. Moreover, a modification of adipogenic differentiation protocol using UCBS indicates that it can be used as a supplement to support differentiation of hBMCs into adipocytes. Our results demonstrate that UCBS not only is suitable for maintenance of murine pancreatic islets, but also supports attachment, propagation, and differentiation of hBMCs in vitro. We conclude that UCBS can serve as a better serum supplement for growth, maintenance, and differentiation of hBMCs, making it a more suitable supplement in cell systems that have therapeutic potential in human transplantation programs.

The object of the present study was to investigate the effect(s) of UV-B irradiation on the functional integrity, metabolic and detoxifying capacity of the isolated goat hepatocytes. Isolated goat hepatocytes were subjected to UV-B irradiation invitro for 0, 250, 500, 1250, 2500 and 7500 Joules/m2 which correspond to the irradiation time of 0, 1, 2, 5, 10 and 30 min. Cells were then analysed for Viability (Trypan blue exclusion test [TBE], 3-[4,5-dimethylthiozol-2yl]-2,5-diphenyltetrazolium bromide [MTT] assay, Membrane integrity (Lactate dehydrogenase [LDH] leakage, Lipid peroxidation) Detoxification (Ureagenesis, Cytochrome P450 activity [CYP450, Diazepam metabolism] and Glutathione-S-Transferase [GST] activity. The results show that there was no difference in functional, metabolic as well as detoxifying parameters of the hepatocytes when irradiated from 0-1250 Joules/m2, whereas a significant alteration was appreciable in the parameters such as LDH leakage, lipid peroxidation, and CYP450 activity when irradiated beyond 1250 Joules/m2. Our present findings suggest that the biologically compatible and feasible dose of UV-B irradiation for xenotransplantation appears to be 1250 Joules/m2.

Ultraviolet-B (UV-B) irradiation in the range of 280-320nm has shown to be a promising immunomodulatory tool in xenogenic hepatocyte transplantation. Most of the studies documenting the effect(s) of UV-B irradiation on hepatic transplantation have been carried out in small model systems with very little information available in larger animals. The aim of the present investigation was to study in vitro the effect(s) of UV-B irradiation (302 nm) at 0, 250, 500, 1250 and 2500 J/m2 on the viability and cellular responses in the isolated goat hepatocytes. The results showed that the cells irradiated at 0, 250, 500, 1250 and 2500 J/m2 demonstrated a viability of 90-95%. However, intracellular [Ca2+]i influx as quantitated by Flu 3-acetete showed a significant increase with irradiation as observed in confocal microscope. The intracellular pH (quantitated by the flourescence of BCCEF) although tend to show an increase with UV-B irradiation was not statistically significant. The present observations suggest that there is a modulation in the intracellular [Ca2+]i concentration within the hepatocytes at higher dose of UV-B irradiation without altering the viability of hepatocytes. These observations are significant for the xenotransplantation of cells.