Growth, photoluminescence, lifetime, and laser damage threshold studies of 1, 3, 5-triphenylbenzene (TPB) single crystal for scintillation application

The 1, 3, 5-triphenylbenzene (TPB) single crystal has been grown using slow cooling seed rotation technique. Optical transmittance of the grown crystal was obtained from UV-Visible analysis. The grown TPB crystal has good transmission in the entire visible region with a lower cutoff wavelength of 330 nm. The solubility of TPB material was determined using toluene as a solvent with different temperatures. The full width at half maximum is 18 arcsec, which indicates that the crystal is of good quality. The TPB crystal was excited (lambda (exc)) at 307 nm, and the corresponding emission (lambda (em)) has been observed at 352 nm. The laser-induced damage threshold (LDT) value of grown crystal is 1.25 GW/cm(2). Third-order nonlinear optical susceptibility chi (3) is determined using the Z-scan technique as 3.07422x10(-09) esu. The TPB crystal proves its suitability for scintillation applications and optoelectronic device fabrications

Association analysis of nine candidate gene polymorphisms in Indian patients with type 2 diabetic retinopathy

<p>Abstract</p> <p>Background</p> <p>Diabetic retinopathy (DR) is classically defined as a microvasculopathy that primarily affects the small blood vessels of the inner retina as a complication of diabetes mellitus (DM).It is a multifactorial disease with a strong genetic component. The aim of this study is to investigate the association of a set of nine candidate genes with the development of diabetic retinopathy in a South Indian cohort who have type 2 diabetes mellitus (T2DM).</p> <p>Methods</p> <p>Seven candidate genes (<it>RAGE, PEDF, AKR1B1, EPO, HTRA1, ICAM </it>and <it>HFE</it>) were chosen based on reported association with DR in the literature. Two more, <it>CFH </it>and ARMS2, were chosen based on their roles in biological pathways previously implicated in DR. Fourteen single nucleotide polymorphisms (SNPs) and one dinucleotide repeat polymorphism, previously reported to show association with DR or other related diseases, were genotyped in 345 DR and 356 diabetic patients without retinopathy (DNR). The genes which showed positive association in this screening set were tested further in additional sets of 100 DR and 90 DNR additional patients from the Aravind Eye Hospital. Those which showed association in the secondary screen were subjected to a combined analysis with the 100 DR and 100 DNR subjects previously recruited and genotyped through the Sankara Nethralaya Hospital, India. Genotypes were evaluated using a combination of direct sequencing, TaqMan SNP genotyping, RFLP analysis, and SNaPshot PCR assays. Chi-square and Fisher exact tests were used to analyze the genotype and allele frequencies.</p> <p>Results</p> <p>Among the nine loci (15 polymorphisms) screened, SNP rs2070600 (G82S) in the <it>RAGE </it>gene, showed significant association with DR (allelic P = 0.016, dominant model P = 0.012), compared to DNR. SNP rs2070600 further showed significant association with DR in the confirmation cohort (P = 0.035, dominant model P = 0.032). Combining the two cohorts gave an allelic P < 0.003 and dominant P = 0.0013). Combined analysis with the Sankara Nethralaya cohort gave an allelic P = 0.0003 and dominant P = 0.00011 with an OR = 0.49 (0.34 - 0.70) for the minor allele. In <it>HTRA1</it>, rs11200638 (G>A), showed marginal significance with DR (P = 0.055) while rs10490924 in LOC387715 gave a P = 0.07. No statistical significance was observed for SNPs in the other 7 genes studied.</p> <p>Conclusions</p> <p>This study confirms significant association of one polymorphism only (rs2070600 in <it>RAGE</it>) with DR in an Indian population which had T2DM.</p

Angiogenic potential of vitreous from proliferative diabetic retinopathy and eales' disease patients

Proliferative Diabetic Retinopathy (PDR) and Eales' Disease (ED) have different aetiologies although they share certain common clinical symptoms including pre-retinal neovascularization. Since there is a need to understand if the shared end-stage angiogenic pathology of PDR and ED is driven by common stimulating factors, we have studied the cytokines contained in vitreous from both patient groups and analyzed the angiogenic potential of these samples in vitro.Vitreous samples from patients with PDR (n = 13) and ED (n = 5) were quantified for various cytokines using a cytokine biochip array and sandwich ELISA. An additional group of patients (n = 5) with macular hole (MH) was also studied for comparison. To determine the angiogenic potential of these vitreous samples, they were analyzed for their ability to induce tubulogenesis in human microvascular endothelial cells. Further, the effect of anti-VEGF (Ranibizumab) and anti-IL-6 antibodies were studied on vitreous-mediated vascular tube formation.Elevated levels of IL-6, IL-8, MCP-1 and VEGF were observed in vitreous of both PDR and ED when compared to MH. PDR and ED vitreous induced greater levels of endothelial cell tube formation compared to controls without vitreous (P<0.05). When VEGF in vitreous was neutralized by clinically-relevant concentrations of Ranibizumab, tube length was reduced significantly in 5 of 6 PDR and 3 of 5 ED samples. Moreover, when treated with IL-6 neutralizing antibody, apparent reduction (71.4%) was observed in PDR vitreous samples.We have demonstrated that vitreous specimens from PDR and ED patients share common elevations of pro-inflammatory and pro-angiogenic cytokines. This suggests that common cytokine profiles link these two conditions

An investigation on the growth and propitiates of KDP admixtured ADP single crystals

ADP:KDP (85:15) mixed crystal was grown using slow cooling technique. The crystalline perfection of the grown crystal was studied using HRXRD curve. The homogeneity of KDP along the length of mixed crystal was analysed. Low Urbach energy value of the grown crystal indicates good crystallinity of the mixed crystals. Etch pit density was found using chemical etching studies. Vickers hardness studies indicate that the quality of the mixed crystal is more stable compared to ADP. The photoconductive nature and piezoelectric coefficient of the crystal were found. The laser stability of the crystal was observed at 532?nm using Nd:YAG laser

Proinflammatory cytokines and angiogenic and anti-angiogenic factors in vitreous of patients with proliferative diabetic retinopathy and eales' disease

Purpose: To investigate the mechanism of angiogenesis in proliferative diabetic retinopathy (PDR) and Eales' disease (ED) on the basis of the levels of proinflammatory cytokines, angiogenic growth factor, and antiangiogenic factor in the vitreous humor. Methods: Twenty-five patients with PDR, 10 patients with ED, and 25 with macular hole (MH) as control subjects were studied. The concentration of the proinflammatory cytokines interleukin-6 (IL-6), IL-8, IL-1&#946;; chemokine-monocyte chemoattractant protein-1 (MCP-1); angiogenic factor-vascular endothelial growth factor (VEGF); and antiangiogenic factor-pigment epithelium derived factor (PEDF) in the vitreous fluid obtained from the eyes during vitrectomy were measured by sandwich enzyme linked immunosorbent assay (ELISA). Results: IL-6, IL-8, MCP-1, and VEGF levels in the vitreous were significantly higher in PDR (P &lt; 0.0001) and ED (P &lt; 0.0001) than in MH patients. Conversely, the vitreous level of PEDF was significantly reduced in PDR (P &lt; 0.0001) but not in ED. A significant correlation was observed between VEGF and IL-6 in ED patients. Conclusion: The authors demonstrate the importance of VEGF in retinal neovascularization of ED which is an idiopathic inflammatory venous occlusion. Further study is required to understand the interrelationship between VEGF and inflammatory cytokines in PDR and ED

Familial exudative vitreoretinopathy (fevr). Clinical profile and management

Purpose: To report our experience with the diagnosis and management of Familial Exudative Vitreoretinopathy (FEVR) in a predominantly older Indian population.. Methods: This prospective interventional non-comparative case series included 38 patients of FEVR and their 23 family members. The diagnosis was established by clinical examination, fluorescein angiography and family screening. Prophylactic photocoagulation/cryotherapy or surgical treatment was done depending on the severity of the disease. Results: The mean age of the patients was 23.6 years. The fundus/fluorescein angiographic findings in 116 eyes of our 61 patients (6 eyes phthisical) were as follows: forty eight (41.4&#x0025;) eyes had only peripheral avascular zone, 8 (6.9&#x0025;) eyes had peripheral new vessels, and 35 (30.1&#x0025;) eyes had retinal detachments (RD) - 10 (8.6&#x0025;) exudative, 5 (4.3&#x0025;) tractional and 20 (17.2&#x0025;) rhegmatogenous. Prophylactic photocoagulation or cryotherapy was done in 34 eyes for retinal holes, local exudative detachments and bleeding new vessels. All the eyes retained stable vision over a mean follow-up of 16 months. Only 14 RDs were suitable for surgery: scleral buckling, vitrectomy or both. The reattachment rate was 85.7&#x0025; (12 of 14) and the best-corrected visual acuity (BCVA) improved to 5/60 or better in 50&#x0025; of these eyes over a 2-year follow-up. Conclusions: FEVR appears to be more common than reported. Timely diagnosis and intervention is essential in view of the lifelong progression of the disease, late exacerbations, frequent involvement of family members, and poor surgical results. A high index of suspicion, family screening and early prophylaxis are recommended to prevent avoidable blindness from this under- diagnosed disease