Differences in glycosylation patterns of heat shock protein, gp96: implications for prostate cancer prevention

Heat shock protein gp96 induces a tumor-specific protective immunity in a variety of experimental tumor models. Because the primary sequences of the glycoprotein, gp96 are identical between tumor and normal tissues, the peptides associated with gp96 and/or the posttranslational modifications of gp96, determine its immunogenicity. Gp96-associated peptides constitute the antigenic repertoire of the source tissue; thus, purified gp96-peptide complexes have clinical significance as autologous cancer vaccines. However, the role of altered glycosylation and its contribution in the biological as well as immunologic activity of gp96 still remains uncharacterized. We examined the cancer-specific glycosylation patterns of gp96. To this end, monosaccharide compositions of gp96 were compared between normal rat prostate and two cancerous rat prostate tissues, nonmetastatic/androgen-dependent Dunning G and metastatic/androgen-independent MAT-LyLu, as well as two human nonmetastatic prostate cancer cell lines, androgen-dependent LnCaP and androgen-independent DU145. Marked differences were observed between the gp96 monosaccharide compositions of the normal and cancerous tissues. Furthermore, gp96 molecules from more aggressive cellular transformations were found to carry decreasing quantities of several monosaccharides as well as sum total content of neutral and amino sugars. We believe that the unique glycosylation patterns contribute to cellular phenotype and that the posttranslational modifications of gp96 may affect its functional attributes.     

Head and neck squamous cell carcinoma: the role of post-operative adjuvant radiotherapy

BACKGROUND: Head and neck squamous cell carcinoma (HNSCC) is one of the leading cancers in India. Since a large majority present in loco-regionally advanced stages, surgery followed by adjuvant post-operative radiotherapy (PORT) has been the mainstay of treatment for resectable HNSCC. AIM: To identify clinico-pathologic factors that could have an impact on outcome in HNSCC in the postoperative setting. MATERIALS AND METHODS: A retrospective review of 348 previously untreated patients with HNSCC who received PORT following curative surgery. The outcome measures were local control, loco-regional control, and disease free survival (DFS). RESULTS: With a median follow-up of 36 months (range: 2-127 months) for surviving patients, the 5-year local control, loco-regional control, and DFS was 79%, 63%, and 56%, respectively for all patients. On univariate analysis, site of primary was an independent prognostic factor for all the outcome measures (P = 0.005, 0.02, and 0.04, respectively) with oral cavity lesions faring the worst. Peri-nodal extension (PNE) affected loco-regional control (P = 0.002) and DFS (P = 0.0005), but was not predictive for local control (P = 0.9852). Cut margin positivity predicted for inferior local control alone (P = 0.03), the significance of which was lost on multivariate analysis. Cox regression analysis however confirmed the significance of primary site and PNE as independent prognostic factors. CONCLUSION: Primary site and PNE are independent factors predicting outcome in the postoperative radiotherapeutic management of HNSCC.     

Recent developments of structure based beta-secretase inhibitors for Alzheimer's disease

The amyloid-beta (Abeta) peptide is the principal components of the senile plaques found in the brains of patients with Alzheimer's disease (AD). The poorly soluble 40-42 amino acid peptide, formed from the cleavage of the Abeta precursor protein (APP) by two proteases, is believed to play a central role in the pathogenesis of AD. Beta-secretase (memapsin 2, BACE1), a membrane-anchored aspartic protease, is responsible for the initial step of APP cleavage leading to the generation of Abeta. Identification and structural determination of beta-secretase have established it to be a primary drug target for AD therapy and stimulated active studies on the inhibitors of this protease. Here we review more recent developments in the design and testing of structure-based beta-secretase inhibitors.     

Effect of tumour necrosis factor-alpha (TNF-alpha) on protein synthesis by mouse preimplantation stage embryos in vitro

Successful blastocyst implantation depends upon the synchronous dialogue between age- and stage-matched embryo and adequately primed maternal endometrium. Endometrial signals present in the uterine lumen influence the growth and the viability of preimplantation stage embryo. Thus, uterine secretion of embryotoxic cytokines may affect the preimplantation stage embryo. Our previous study in the rhesus monkey has indicated that tumor necrosis factor-alpha (TNF-alpha) is one such candidate present in the uterine lumen, which may act as an embryotoxic agent. In the present study, the effect of TNF-alpha on de novo protein synthesis by mouse morulae (n = 100) and blastocysts (n = 100) in vitro was investigated by 2D-polyacrylamide gel electrophoresis. A total of 35 and 40 protein spots were detected in lysates of control morulae and blastocysts, respectively. Exposure of embryos to TNF-alpha (50 ng/ml) reduced the number of protein spots to 15 and 17 compared to that of control morulae and blastocysts. Seven spots in morula and 13 protein spots in blastocyst flourograms showed quantitative changes in their expressions with exposure to TNF-alpha. Morulae and blastocysts exposed to TNF-alpha expressed 8 and 17 protein spots, respectively, that were not seen in control embryos. It appears from the present study that exposure of preimplantation stage embryos to TNF-alpha affects their protein synthesis both quantitatively and qualitatively.     

QSAR modeling on dopamine D2 receptor binding affinity of 6-methoxy benzamides

QSAR modeling was performed on 58 (S) N-[(1-ethyl-2-pyrrolidinyl) methyl]-6-methoxy benzamides as dopamine (DA) D2 receptor antagonists to identify the structural requirements for DA D2 receptor binding affinity. The study pointed out that the presence of hydrophobic substituents at R3 position and electron-donating groups at R5 position increased the biological activity. Substitutions at phenyl ring favored the binding affinity of these benzamides. Ethyl group and iodine at R3 position were advantageous to the activity whereas nitro group at phenyl ring hindered the antagonistic activity.     

Design and synthesis of peptidomimetic severe acute respiratory syndrome chymotrypsin-like protease inhibitors

Design, synthesis, and biological evaluation of peptidomimetic severe acute respiratory syndrome chymotrypsin-like protease (SARS-3CLpro) inhibitors for severe acute respiratory syndrome coronavirus (SARS-CoV) are described. These inhibitors exhibited antiviral activity against SARS-CoV in infected cells in the micromolar range. An X-ray crystal structure of our lead inhibitor (4) bound to SARS-3CLpro provided important drug-design templates for the design of small-molecule inhibitors.     

Structural analysis of isoform-specific inhibitors targeting the tetrahydrobiopterin binding site of human nitric oxide synthases

Nitric oxide synthesized from l-arginine by nitric oxide synthase isoforms (NOS-I-III) is physiologically important but also can be deleterious when overproduced. Selective NOS inhibitors are of clinical interest, given their differing pathophysiological roles. Here we describe our approach to target the unique NOS (6R,1'R,2'S)-5,6,7,8-tetrahydrobiopterin (H(4)Bip) binding site. By a combination of ligand- and structure-based design, the structure-activity relationship (SAR) for a focused set of 41 pteridine analogues on four scaffolds was developed, revealing selective NOS-I inhibitors. The X-ray crystal structure of rat NOS-I dimeric-oxygenase domain with H(4)Bip and l-arginine was determined and used for human isoform homology modeling. All available NOS structural information was subjected to comparative analysis of favorable protein-ligand interactions using the GRID/concensus principal component analysis (CPCA) approach to identify the isoform-specific interaction site. Our interpretation, based on protein structures, is in good agreement with the ligand SAR and thus permits the rational design of next-generation inhibitors targeting the H(4)Bip binding site with enhanced isoform selectivity for therapeutics in pathology with NO overproduction.     

Effectiveness of emergency argon laser retinopexy performed by trainee doctors

OBJECTIVE: To report the outcomes following treatment of retinal tears with argon laser photocoagulation by trainee doctors as an emergency procedure. METHODS: Retrospective, case note analysis of 100 consecutive patients treated between August 2000 and December 2002 at a tertiary referral hospital. RESULTS: The case notes of 100 consecutive patients (41 male, 59 female) with a mean age of 57.5 years were reviewed. Out of these 90 were symptomatic. The follow-up period ranged from 1 week to 8 months. All patients had argon laser retinopexy in the Emergency department. The on-call Registrar performed the procedure on 94 patients, and Senior House Officers performed the other six. A total of 98 procedures were performed on the slit lamp and two by laser indirect ophthalmoscope. In all, 24 patients needed further treatment with either indirect laser, cryotherapy, or surgery. At the last follow-up, all the patients had anatomically attached retinas. CONCLUSION: A significant proportion of patients (24%) undergoing laser retinopexy in the emergency department needed further treatment. The relative inexperience in using the indirect laser, together with its unavailability in the Emergency department, may be the contributory factors. There seems to be scope for supervised training in using the laser indirect ophthalmoscope for the trainees in the Ophthalmic Emergency department.     

In vitro and in vivo antimicrobial action of tea: the commonest beverage of Asia

The methanolic extract of leaves of Camellia sinensis (L) O. KUNTZE was screened for antimicrobial property against 111 bacteria comprising 2 genera of Gram positive and 7 genera of Gram negative bacteria. Most of these strains were inhibited by the compound at 10-50 microg/ml level and few strains were sensitive even at lower concentrations (5 microg/ml). The bacteria could be arranged in the decreasing order of sensitivity towards the compound in the following manner: Staphylococcus aureus, Vibrio cholerae, Escherichia coli, Shigella spp., Salmonella spp., Bacillus spp., Klebsiella spp. and Pseudomonas aeruginosa. The antibacterial activity of compound could also be confirmed in vivo. When it was given to Swiss strain of white mice at different dosages (30, 60 microg/mouse), it could significantly protect the animals challenged with 50 MLD of Salmonella typhimurium NCTC 74. According to Chi square test the in vivo data were highly significant (p<0.001).     

Attenuation of hyperglycemia and hyperlipidemia in streptozotocin-induced diabetic rats by aqueous extract of seed of Tamarindus indica

Streptozotocin (STZ)-induced diabetic rats were divided into mild diabetic (MD) and severe diabetic (SD) on the basis of fasting blood glucose (FBG) levels. Diabetes was confirmed here by intravenous glucose tolerance test (GTT), biochemical assay of glycogen content in liver and skeletal muscle, glucose-6-phosphatase activity in liver, and serum insulin levels. Hyperlipidemia developed in these experimental diabetic rats was assessed by quantification of total cholesterol (TC), high-density lipoprotein cholesterol (HDLc), low-density lipoprotein cholesterol (LDLc) and triglyceride (TG) in serum. Aqueous extract of seed of Tamarindus indica was given to MD and SD rats at the dose of 80 mg and 120 mg/0.5 ml distilled water/100 g body weight/d respectively for 14 d. Significant attenuation of hyperglycemia was indicated by measuring FBG, glycogen level and glucose-6-phosphatase activity along with monitoring of intravenous GTT and serum insulin level. Similarly, correction of hyperlipidemia in diabetic rats after this extract supplementation was confirmed by significant reduction in the levels of above-mentioned hyperlipidemic indicators. Intravenous GTT was performed that highlights the antidiabetic action of this extract is not due to its effect on the intestinal rate of glucose absorption but may be due to modulation of intracellular glucose utilization in target organs. This study focus the efficacy of this extract for the management of experimental diabetes in rat model which may shed some light on the scientific basis of ancient herbal therapy in this line using this seed.