Structures of Preferred Human IgV Genes-Based Protective Antibodies Identify How Conserved Residues Contact Diverse Antigens and Assign Source of Specificity to CDR3 Loop Variation.

The human Ab response to certain pathogens is oligoclonal, with preferred IgV genes being used more frequently than others. A pair of such preferred genes, IGVK3-11 and IGVH3-30, contributes to the generation of protective Abs directed against the 23F serotype of the pneumonococcal capsular polysaccharide of Streptococcus pneumoniae and against the AD-2S1 peptide of the gB membrane protein of human CMV. Structural analyses of Fab fragments of mAbs 023.102 and pn132p2C05 in complex with portions of the 23F polysaccharide revealed five germline-encoded residues in contact with the key component, l-rhamnose. In the case of the AD-2S1 peptide, the KE5 Fab fragment complex identified nine germline-encoded contact residues. Two of these germline-encoded residues, Arg91L and Trp94L, contact both the l-rhamnose and the AD-2S1 peptide. Comparison of the respective paratopes that bind to carbohydrate and protein reveals that stochastic diversity in both CDR3 loops alone almost exclusively accounts for their divergent specificity. Combined evolutionary pressure by human CMV and the 23F serotype of S. pneumoniae acted on the IGVK3-11 and IGVH3-30 genes as demonstrated by the multiple germline-encoded amino acids that contact both l-rhamnose and AD-2S1 peptide.

Discovery of inhibitors of Shiga toxin type 2 by on-plate generation and screening of a focused compound library.

A new microtiter-plate-based method for the rapid generation and evaluation of focused compound libraries was developed and applied to screening ligand analogues for the E. coli Shiga-like toxin Stx2a. The method is general, it mitigates the masking of intrinsic affinity gains by multivalency and enables the discovery of potential hits when starting from ligands that exhibit extremely low affinity with proteins that depend on multivalency for their function.

Use of N,O-dimethylhydroxylamine as an anomeric protecting group in carbohydrate synthesis.

The N,O-dimethyloxyamine-N-glycosides are introduced as anomerically protected building blocks for carbohydrate synthesis. These N-glycosides are stable to a variety of protecting group manipulations including acylation, alkylation, silylation, and acetal formation. The alkoxyamine-N-glycosides can be cleaved selectively with N-chlorosuccinimide to give the desired hemiacetals in excellent yield. Furthermore, these N-glycosides are stable to the activation conditions required for glycosylation using thioglycoside and trichloroacetimidate glycosyl donors suggesting N,O-dialkoxyamine-N-glycosides will be useful for complex oligosaccharide synthesis.

Real time HR-MAS NMR: application in reaction optimization, mechanism elucidation and kinetic analysis for heterogeneous reagent catalyzed small molecule chemistry.

A novel application of in situ (1)H high-resolution magic angle spinning (HR-MAS) NMR technique for real-time monitoring of H(2)SO(4)-silica promoted formation of 2, 2-disubstituted quinozolin-4(3H)-ones is reported. The detailed NMR spectroscopic data led to elucidation of the mechanism, reaction optimization, kinetics and quantitative analysis of the product accurately and efficiently. The translation of the optimized parameters obtained by (1)H HR-MAS NMR in the wet laboratory provided similar results. It is proposed that (1)H HR-MAS has a potential utility for optimization of various organic transformations in solid supported catalyzed reactions.

NIS/H2SO4-Silica: a mild and efficient reagent system for the hydrolysis of thioglycosides.

Chemoselective hydrolysis of a variety of thioglycosides in the presence of a wide range of protecting groups has been achieved by using N-iodosuccinimide and H(2)SO(4) immobilized on silica in good to excellent yields.

Early prediction of acute kidney injury by clinical features of snakebite patients at the time of hospital admission.

BACKGROUND: Snakebite is a major health problem in India. Venomous snakebite, which is an important medical hazard in several tropical countries including India, affects thousands of people per year and some of them develop acute kidney injury (AKI). AIMS: This study was performed to find out 1) early clinical predictors for acute kidney injury in snakebite patients at the time of hospital admission and 2) incidence of acute kidney injury in snakebite patients. MATERIALS AND METHODS: 171 consecutively admitted non-diabetic, non-hypertensive snakebite patients were examined. Multivariate linear regression analysis with 95 percent confidence interval (CI) was done for statistical analysis. Analyses were performed by software Statistical Package for the Social Sciences (SPSS) (17(th) version for Windows). RESULTS: Incidence of acute kidney injury was 43.27%. Development of acute kidney injury was independently associated with 20 min whole blood clotting test (20 min WBCT) (P value = 0.029; CI 95%), dark or brown color urine (P value = 0.000; CI 95%), and time interval between snakebite and anti-snake venom administration (P value = 0.000; CI 95%). Age (P value = 0.011; CI 95%) and presence of neurological signs (P value = 0.000; CI 95%) were negatively correlated with development of acute kidney injury. CONCLUSION: Incidence of acute kidney injury is slightly higher in our study than previous studies. Early prediction of acute kidney injury development in snakebite patients can be done by presence of black or brown urine, 20 min WBCT > 20 min, and increased time interval between snakebite and administration of anti-snake venom at the time of hospital admission. Young age group of snakebite patients develops acute kidney injury more commonly.

Carotid artery intima media thickness as a surrogate marker of atherosclerosis in patient with chronic renal failure on hemodialysis.

BACKGROUND: In patients with chronic renal failure (CRF), carotid artery intima media thickness (CAIMT) is increased when the patients are on hemodialysis. Vascular events caused by atherosclerosis are the major cause of death in patients undergoing hemodialysis. AIMS: This study was done to find out the relationship between carotid artery intima media thickness and hemodialysis in chronic renal failure patients independent of classical risk factors and also the relationship between CAIMT of hemodialyzed patients and nonhemodialyzed CRF patients. MATERIALS AND METHODS: In this observational study, CAIMT of 78 CRF patients was examined by B-mode ultrasonography. Glomerular filtration rate (GFR) was calculated by using the "Modification of Diet in Renal Disease" formula. CRF patients, who had been on regular hemodialysis treatment (treated thrice weekly) for at least 6 months, were identified as hemodialyzed patients. Data were analyzed by software Statistical package for the social Sciences (SPSS) (17(th) version). RESULTS: There was significant positive correlation between CAIMT and hemodialysis (P=0.045) independent of traditional risk factors. Hemodialyzed patients had higher mean CAIMT (1136.30±21.21 µm, P<0.001) than mean CAIMT of age and sex matched nondialyzed patients (959.30±23.01 µm). CONCLUSION: Hemodialysis is an independent risk factor for atherosclerosis in CRF patents. Hemodialyzed patients have significantly higher CAIMT than nondialyzed CRF patients.

Measurement of intima media thickness of carotid artery by B-mode ultrasound in healthy people of India and Bangladesh, and relation of age and sex with carotid artery intima media thickness: An observational study.

BACKGROUND: Carotid artery intima media is a surrogate marker of atherosclerosis and related with ethnicity, age, sex, traditional and non-traditional risk factors. Black ethnicity is related to greater mean and maximum carotid artery intima media thickness when compared to South Asians. Our study was done to find out the mean carotid artery intima media thickness (CAIMT) of normal healthy people of India and Bangladesh, and the relationship of non-modifiable risk factors such as age and sex with CAIMT. MATERIALS AND METHODS: In this observational study, CAIMT of 93 people were examined by B-mode ultrasonography. All subjects underwent a careful interview and clinical, radiological, biochemical examination. Data was analyzed by software statistical package for social sciences (SPSS) (17(th) version for window). RESULTS: In our study, the mean CAIMT of healthy subjects including all age group was (754.94 ± 11.96 micron.). Mean CAIMT was higher in age group of 61-80 years (908.75 ± 39.02 micron) than age group of 20-40 years (713.62 ± 16.59 micron) and 41-60 years (745.55 ± 13.05 micron). CAIMT was positively correlated with age (P value <0.001) and sex (P value=0.001). CONCLUSION: An aggregated analysis based on this study in different age groups of healthy people may be useful for assessing carotid artery abnormalities as an aid to defining abnormalities and predicting risk of atherosclerosis in individual healthy people living in India and Bangladesh.

Protecting-group-free synthesis of glycosyl 1-phosphates.

Glycosyl 1-phosphates enriched in the α-anomer are obtained without the use of protecting groups in two steps starting from the free hemiacetal. Condensation of free hemiacetals with toluenesulfonylhydrazide yields a range of glycosylsulfonohydrazide donors which can be oxidized using cupric chloride in the presence of phosphoric acid and the coordinating additive 2-methyl-2-oxazoline to give useful yields of the fully deprotected glycosyl 1-phosphates.

A study of atherosclerosis in patients with chronic renal failure with special reference to carotid artery intima media thickness.

OBJECTIVES: Cardiovascular disease is the leading cause of morbidity and mortality in patients with chronic renal failure (CRF). This study attempts to identify the factors responsible for atherosclerosis in CRF patients using carotid artery intima media thickness (CAIMT) as a surrogate marker of atherosclerosis. MATERIALS AND METHODS: CAIMT was measured by high-resolution B-mode ultrasonography in 100 CRF patients and 50 age- and sex-matched healthy controls. Data were analyzed by software SPSS (17(th) version) for Windows. RESULTS: CRF patients had a significantly higher CAIMT (1026.83 ± 17.19 micron, mean ± SE, P < 0.001) than age- and sex-matched healthy controls (722.46 ± 7.61 micron). There was inverse correlation between CAIMT and glomerular filtration rate (GFR) (P < 0.001) independent of traditional risk factors. There was also significant positive correlation between CAIMT and traditional risk factors of atherosclerosis. Ischemic heart disease (IHD) also showed positive correlation with CAIMT (P = 0.007) and inverse correlation with GFR (P = 0.005). CONCLUSIONS: There is high prevalence of atherosclerosis in CRF patients. CAIMT can be used to detect and predict future incidence of IHD in CRF patients.

Prevalence of rheumatic conditions in patients with diabetes mellitus in a tertiary care hospital.

Musculoskeletal disorders are common in diabetic subjects. The pathophysiology of these disorders in diabetic patients is not obvious. It could be due to connective tissue disorders, glycosylated end products, vasculopathy, neuropathy or combinations. A wide range of musculoskeletal syndromes have been described in association with diabetes, namely diabetic cheiro-arthropathy, adhesive capsulitis of shoulder, carpal tunnel syndrome, Dupuytren's contracture, hyperostosis, osteo-arthritis, hyperuricaemia, etc. This study was undertaken to find out the prevalence of these conditions in diabetes mellitus and to look for any associations with diabetic complications or therapy. A tertiary care centre-based cross-sectional study was carried out among 100 consecutive diabetic patients (WHO criteria) attending medicine department who were enrolled. The study was done at Calcutta National Medical College and Hospital, Kolkata, from March 2008 to February 2009. The diagnoses of the rheumatic conditions were made by unbiased clinical observations on the basis of standardised case definitions or criteria. Limited joint mobility (29%), adhesive capsulitis (18%), and osteo-arthritis of knee (27%) or hand (17%) were the most common rheumatic conditions in diabetics. Trigger finger (flexor tenosynovitis) and carpal tunnel syndrome were also present in 7% and 5% cases of diabetics respectively. Although hyperuricaemia was present in 9%, clinical gout was present in only 4%. There was no clear association of these syndromes with diabetic renal disease or micro-albuminuria. Most of these conditions were noted in chronic long duration diabetic subjects.

Synthesis of a core disaccharide from the Streptococcus pneumoniae type 23F capsular polysaccharide antigen.

The synthesis of methyl α-l-rhamnopyranosyl-(1→2)-ß-d-galactopyranoside and methyl α-l-rhamnopyranosyl-(1→2)-3-(glycer-2-yl-phosphate)-ß-d-galactopyranoside disaccharides from the Streptococcuspneumoniae type 23F capsular polysaccharide is reported. A simple protecting group strategy was followed using commercially available monosaccharides and phosphorylating reagents. H-Phosphonate and phosphoramidite coupling chemistries were explored for introducing the phosphodiester. Hydrazine hydrate was found to be a mild and efficient deacetylating agent, which was required to avoid phosphate migration during the deprotection of the phosphodiester functionalized disaccharide.