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Biomedical subjects

M Ghosh

Publications and source records attributed to M Ghosh.

At least 37 records · Page 2Linked to original sources
PubMed2000

Rapid detection of respiratory viruses by centrifugation enhanced cultures from children with acute lower respiratory tract infections.

BACKGROUND: Acute respiratory tract infection (ARI) is the major cause of morbidity and mortality in young children in developing countries. Information on viral aetiology in ARI in India is very limited. OBJECTIVE: The aim of the study was to define the role of viruses in acute lower respiratory tract infections (ALRTI) in children in India using centrifugation enhanced cultures followed by indirect immunofluorescence (IIF). STUDY DESIGN: Nasopharyngeal aspirates (NPAs) were collected from children from September 1995 to April 1997, attending paediatric clinic of All India Institute of Medical Sciences (AIIMS) with symptoms of ALRTI. Virus isolation was done by centrifugation enhanced cultures using HEp-2, LLC-MK2 and MDCK cells. The viruses were identified at 24-48 h post inoculation by IIF staining using monoclonal antibodies to respiratory syncytial virus (RSV), parainfluenza virus (PIV), influenza virus and adenovirus. RESULTS: Of 200 NPA samples, 89 (44.5%) were positive for one or more viral pathogens. RSV was detected in 34 (17%) of all ALRTI cases followed by influenza viruses in 29 (14.5%), PIVs in 23 (11.5%) and adenoviruses in three (1.5%). In 79 children with bronchiolitis, RSV was most frequently isolated (25%) pathogen, while in bronchopneumonia cases (101) the most common viral pathogen was influenza virus (17%). In eight cases (4%) of ALRTI dual infections were detected. In 100 NPA specimens IIF staining on direct cell smears was carried out and viruses were detected in only 17%. RSV and influenza virus infection peaked from September to December, where as PIV infections were more frequent from January to April. CONCLUSION: Respiratory viruses accounted for 44.5% of cases of ALRTI in India and the results of viral aetiology could be given in 24-48 h using centrifugation enhanced cultures. RSV was the most common viral agent associated with ALRTI in children under 5 years of age with greater association with bronchiolitis.

Adenoviruses, Human↗
PubMed2000

Structure of human transthyretin complexed with bromophenols: a new mode of binding.

The binding of two organohalogen substances, pentabromophenol (PBP) and 2,4,6-tribromophenol (TBP), to human transthyretin (TTR), a thyroid hormone transport protein, has been studied by in vitro competitive binding assays and by X-ray crystallography. Both compounds bind to TTR with high affinity, in competition with the natural ligand thyroxine (T(4)). The crystal structures of the TTR-PBP and TTR-TBP complexes show some unusual binding patterns for the ligands. They bind exclusively in the 'reversed' mode, with their hydroxyl group pointing towards the mouth of the binding channel and in planes approximately perpendicular to that adopted by the T(4) phenolic ring in a TTR-T(4) complex, a feature not observed before. The hydroxyl group in the ligands, which was previously thought to be a key ingredient for a strong binding to TTR, does not seem to play an important role in the binding of these compounds to TTR. In the TTR-PBP complex, it is primarily the halogens which interact with the TTR molecule and therefore must account for the strong affinity of binding. The interactions with the halogens are smaller in number in TTR-TBP and there is a decrease in affinity, even though the interaction with the hydroxyl group is stronger than that in the TTR-PBP complex.

Binding Sites↗
PubMed2000

Evaluation of a PCR primer based on the isocitrate dehydrogenase gene for detection of Helicobacter pylori in feces.

In order to improve detection and identification of Helicobacter pylori in highly contaminated samples, we evaluated new specific primers based on the DNA base sequence within the isocitrate dehydrogenase (icd) gene to amplify a 1,200-bp DNA segment. The specificity of the icd primer was tested against DNA derived from various bacteria, including 7 Helicobacter species and a panel of 1 gram-variable, 2 gram-positive, and 16 gram-negative bacteria, as well as DNA from houseflies and feces from H. pylori-negative patients. The primers permitted the detection of all clinical H. pylori isolates tested, but no reactions were observed with negative controls. Several procedures for DNA extraction from feces were evaluated using PCR with icd primers. The lower limits of detection of H. pylori DNA from two different sources containing the same number of H. pylori organisms, a pure culture and feces spiked with H. pylori, were established for each extraction method tested. The results were 8.0 x 10(3) CFU/ml for cultures of pure H. pylori, and 8.0 x 10(6) CFU/ml for H. pylori from feces, using the phenol-chloroform method; 8.0 x 10(2) and 7.0 x 10(3) CFU/ml, respectively, for a glass matrix and chaotropic solution protocol; 8.0 x 10(2) and 7.0 x 10(3) CFU/ml, respectively, for the QIAamp tissue kit; and 5.0 x 10(2) and 5.0 x 10(3) CFU/ml, respectively, for the XTRAX DNA extraction kit. We conclude that the use of the icd gene as a primer for PCR represents a specific and sensitive assay for detection of H. pylori in highly contaminated samples.

Animals↗
PubMed2000

Cyclooxygenase expression in the gallbladder.

The COX expressions were evaluated separately in the epithelium and in the stroma of gallbladder cancer, chronic cholecystitis, xanthogranulomatous cholecystitis (XGC) and the normal gallbladder. In normal gallbladder COX-2 expression rate was significantly higher in the epithelium than in the stroma. The COX-2 expression rate in the epithelium of non-cancerous adjacent epithelium to cancerous lesion was significantly lower than those not only of cancer, but also chronic cholecystitis, XGC and normal gallbladder. In stroma, the COX-2 expression rate in cancer, chronic cholecystitis and XGC were significantly higher than that of the normal gallbladder. The rate in non-cancerous adjacent stroma to cancer is significantly lower than that of cancer and XGC. However, the difference of rate between of normal and of chronic cholecystitis was not significant. The COX-2 expression rates were significantly higher in both the epithelium and the stroma in the well and moderately differentiated cancer group than in the poorly and undifferentiated cancer group. Our results suggest that COX-2 expression in the gallbladder may be regulated by various factors and not directly related to carcinogenesis. The significance of its repression in the non-cancerous adjacent tissue to cancer lesion should be re-evaluated.

Cholecystitis↗
PubMed1999

Inhibition of phosphatase activity by positively-charged cyclodextrins.

[formula: see text] Aminocyclodextrins are known to bind phosphate esters such as phosphotyrosine and p-nitrophenyl phosphate. This paper describes the inhibition of phosphate ester hydrolysis, as catalyzed by lambda-protein phosphatase and acid phosphatase, that is caused by such binding interactions. ROESY studies provide structural information about the cyclodextrin-aryl phosphate complexes. In addition, these experiments are used to generate approximations of the rates of dissociation of the noncovalent complexes.

Acid Phosphatase↗
PubMed1999

Structural characterisation of a uracil containing hairpin DNA by NMR and molecular dynamics.

Three-dimensional (3D) structure of a hairpin DNA d-CTAGAGGATCCTTTUGGATCCT (22mer; abbreviated as U4-hairpin), which has a uracil nucleotide unit at the fourth position from the 5' end of the tetra-loop has been solved by NMR spectroscopy. The(1)H resonances of this hairpin have been assigned almost completely. NMR restrained molecular dynamics and energy minimisation procedures have been used to describe the 3D structure of the U4 hairpin. This study establishes that the stem of the hairpin adopts a right handed B-DNA conformation while the T(12)and U(15)nucleotide stack upon 3' and 5' ends of the stem, respectively. Further, T(14)stacks upon both T(12)and U(15)while T(13)partially stacks upon T(14). Very weak stacking interaction is observed between T(13)and T(12). All the individual nucleotide bases adopt ' anti ' conformation with respect to their sugar moiety. The turning phosphate in the loop is located between T(13)and T(14). The stereochemistry of U(15)mimics the situation where uracil would stack in a B-DNA conformation. This could be the reason as to why the U4-hairpin is found to be the best substrate for its interaction with uracil DNA glycosylase (UDG) compared to the other substrates in which the uracil is at the first, second and third positions of the tetra-loop from its 5' end, as reported previously.

Carbohydrates↗
PubMed1999

Nuclear localization of the protein from the open reading frame x1 of the Borna disease virus was through interactions with the viral nucleoprotein.

Previous studies have predicted the presence of a small open reading frame (ORFx1) located between ORF-1 and ORF-2 of the Borna disease viral (BDV) genome. The ORFx1 is expressed as a p10 protein that is localized in the nucleus and cytoplasm of BDV-infected cells. In this study, we cloned the nucleotide sequence of ORFx1 into expression vectors and showed that it is expressed as p10. An anti-p10 serum gave nuclear and cytoplasmic staining of cells persistently infected with BDV. Immunoprecipitation of p10 from BDV-infected cells coprecipitated the p40 nucleoprotein N and the 24-kDa viral phosphoprotein P. Transient transfection of noninfected cells showed that p10 and p40 can be coprecipitated and revealed that p10 localized in the cytoplasm was imported into the nucleus in the presence of the BDV p40 N. In vitro protein-protein interaction studies on solid phase showed the direct interaction of the p10 with the BDV N protein. The subcellular distribution of p10 and its interaction with p40 suggest that this protein may play a role in the nuclear replication and/or transcription of BDV.

Amino Acid Sequence↗
PubMed1999

Molecular cloning and expression of adenosine kinase from Leishmania donovani: identification of unconventional P-loop motif.

The unique catalytic characteristics of adenosine kinase (Adk) and its stage-specific differential activity pattern have made this enzyme a prospective target for chemotherapeutic manipulation in the purine-auxotrophic parasitic protozoan Leishmania donovani. However, nothing is known about the structure of the parasite Adk. We report here the cloning of its gene and the characterization of the gene product. The encoded protein, consisting of 345 amino acid residues with a calculated molecular mass of 37173 Da, shares limited but significant similarity with sugar kinases and inosine-guanosine kinase of microbial origin, supporting the notion that these enzymes might have the same ancestral origin. The identity of the parasite enzyme with the corresponding enzyme from two other sources so far described was only 40%. Furthermore, 5' RNA mapping studies indicated that the Adk gene transcript is matured post-transcriptionally with the trans-splicing of the mini-exon (spliced leader) occurring at nt -160 from the predicted translation initiation site. The biochemical properties of the recombinant enzyme were similar to those of the enzyme isolated from leishmanial cells. The intrinsic tryptophan fluorescence of the enzyme was substrate-sensitive. On the basis of a multiple protein-alignment sequence comparison and ATP-induced fluorescence quenching in the presence or the absence of KI and acrylamide, the docking site for ATP has been provisionally identified and shown to have marked divergence from the consensus P-loop motif reported for ATP- or GTP-binding proteins from other sources.

Acrylamide↗
PubMed1999

Pathways of As(III) detoxification in Saccharomyces cerevisiae.

Saccharomyces cerevisiae has two independent transport systems for the removal of arsenite from the cytosol. Acr3p is a plasma membrane transporter that confers resistance to arsenite, presumably by arsenite extrusion from the cells. Ycf1p, a member of the ABC transporter superfamily, catalyzes the ATP-driven uptake of As(III) into the vacuole, also producing resistance to arsenite. Vacuolar accumulation requires a reductant such as glutathione, suggesting that the substrate is the glutathione conjugate, As(GS)3. Disruption of either the ACR3 or YCF1 gene results in sensitivity to arsenite and disruption of both genes produces additive hypersensitivity. Thus, Acr3p and Ycf1p represent separate pathways for the detoxification of arsenite in yeast.

ATP-Binding Cassette Transporters↗
PubMed1999

Evaluation of toxicity of beta-tethymustine, a new anticancer compound, in mice.

The toxicity of beta-tethymustine, a potential anticancer compound 1 ((Cancer Lett., 119 (1997) 7-12) was assessed in normal as well as in Ehrlich ascites carcinoma (EAC), Sarcoma-180 (S-180) and Dalton' s Lymphoma (DL) tumour-bearing Swiss male mice by measuring drug-induced changes in haematological parameters, femoral bone marrow cellularity and splenic cellularity on days 9, 15 and 21 following drug treatment at the optimum dose of 8.0 mg/kg body weight from days 1 to 7. Detailed studies were also made by noting sequential changes in the above parameters in normal and EAC-bearing mice on days 12 and 18, respectively. The results indicate that the compound did not adversely affect haematopoiesis as it was observed that no significant decrease in haematological parameters and femoral marrow cellularity occurred in treated groups. Initial hyposplenic activity was, however, noted in EAC and normal treated groups on day 9 which soon reached normal count within 7-10 days after termination of drug therapy. Drug-induced hepatotoxicity and nephrotoxicity were also sequentially evaluated in normal and tumour-bearing mice on days 9, 15 and 21 but no such toxicities were detected. Also, body weight, skin and hair texture, and behavioural pattern (food and water intake and activity) did not reflect any toxic reaction in host mice at this optimum dose.

Animals↗
PubMed1999

CD40 and Bcl2 expression in squamous cell carcinoma of the lung: correlation with apoptosis, survival, and other clinicopathological factors.

CD40 is a cell surface receptor which, when ligated, modulates apoptosis in some cell types, perhaps via activation of the expression of members of the Bcl2 gene family. This study sought to determine whether expression of CD40 in a series of 134 squamous cell carcinomas (SCCs) of the lung was related to apoptosis or clinical parameters, either alone or in connection with Bcl2 expression. Sections of SCCs were stained for CD40 and Bcl2 by immunohistochemical techniques. An index was determined for these two markers by counting stained and unstained malignant cells under high power. Sections were also stained by haematoxylin and eosin for determination of the apoptotic index by counting apoptotic bodies. About 40 per cent of SCCs expressed CD40 in at least some of the malignant cells, with about 10 per cent essentially uniformly stained. Similar proportions expressed Bcl2, with a tendency for expression to be mutually excluisve. Apoptosis did not correlate with CD40 expression, nor was there evidence of a co-operative or an antagonistic effect with Bcl2. Bcl2 expression, on the other hand, correlated significantly with the apoptosis score. CD40 expression showed no significant relationship with survival or any other clinicopathological parameter except ploidy. Bcl2 expression, however, correlated with longer survival. It is concluded that CD40 expression in SCC of the lung does not by itself relate to apoptosis, nor is it a useful indicator of prognosis.

Adult↗
PubMed1999

Evaluation of 2-(methylaminosulfonyl)-1-(arylsulfonyl)hydrazines as anticancer agents.

Seven new 2-(methylaminosulfonyl)- 1-(arylsulfonyl)hydrazines were prepared and evaluated as potential antitumor agents in vivo against murine Ehrlich ascites carcinoma (EAC). Borderline in vivo activity in EAC was exhibited by two compounds. All of them were screened in vitro against a battery of human tumor cell lines at the National Cancer Institute (NCI), USA. One of them, namely compound 2f(NSC No. 649 752) displayed highly significant specificity in two different cell lines as non-small cell lung cancer line HOP-18 and in CNS cancer line SNB-19. The compounds assessed in vitro for anti-HIV activity also at the NCI, however, have not reached the criteria of significant activity. The alkylating activity of the compounds was determined by measuring the absorbance of the alkylated product of 4-(4-nitrobenzyl)pyridine. It was found that they are capable of acting as chemical alkylating agents.

Animals↗
PubMed1998

Development and control of the circadian pacemaker for melatonin release in the chicken pineal gland.

UNLABELLED: Melatonin (MT) release from explanted pineal glands of 3- to 20-week-old chicken was investigated in a 5-day perifusion system. Both the chicken and the explanted glands were exposed to various environmental lighting regimens. OBSERVATIONS: (1) The explanted chicken pineal is sensitive to direct light. Continuous illumination during the in vitro period abolishes the circadian rhythm of the MT secretion in 3 days. Continuous darkness has limited effect. (2) Reverse illumination completely reverses the MT cycle in 2 days. (3) Rhythmic illumination with short (6-h) periods only slightly modulates the MT release pattern: the basic, 24-h periodicity is preserved. (4) The circadian MT pacemaker develops normally and becomes synchronized to the day even if the chicken has never experienced alteration in the environmental illumination (those hatched and bred under continuous illumination). The explanted pineal from these chickens exhibits normal MT cycle and light sensitivity. Conclusion, Chicken pineal contains a complete, genetically coded circadian pacemaker with a fixed frequency. The pacemaker is synchronized to the day by the altered environmental illumination and by at least one other, unknown environmental factor. With altered illumination, in vitro, the 24-h periodicity of the pacemaker cannot be changed significantly, but its phase can be shifted. In contrast to conclusions obtained from in vivo observation in mammals, light seems to stimulate MT secretion from the avian pineal in vitro. For development and daily synchronization of the circadian MT pacemaker in the chicken pineal gland, periodic changes in the environmental illumination are not necessary.

Animals↗
PubMed1998

Kreb's TCA cycle in Halobacterium salinarum investigated by 13C nuclear magnetic resonance spectroscopy.

Kreb's tricarboxylic (TCA) cycle was studied in Halobacterium salinarum cells grown in the presence of glucose or alanine. The cells were incubated with 13C-labeled substrate and the labeling pattern of various carbon positions in glutamate was monitored by 13C-NMR spectroscopy. [2-13C]pyruvate, when used as a substrate, led mainly to signals for C-1 and C-5 glutamate, with some C-3 glutamate. [3-13C]pyruvate as a substrate produced signals, mainly C-2, C-3, and C-4 glutamate, with some C-1 and C-5 glutamate. The multiplicity of the signals and observation of a C-1 signal in this case indicates extensive cycling of the label in the TCA cycle. Isotopomer analysis of glutamate labeling suggested that of the total pyruvate entering the TCA cycle, the flux through pyruvate:ferredoxin oxidoreductase was 90% while that through pyruvate carboxylase was 10%. Only 53% of the total acetyl-CoA was produced from the added labeled pyruvate, the rest being generated endogenously. In the presence of nitrogen, mainly transamination reaction products were formed in the case of both these substrates.

Alanine↗
PubMed1998

The structure and function of the PQQ-containing quinoprotein dehydrogenases.

Bacterial methanol and glucose dehydrogenases containing a novel type of prosthetic group, subsequently identified as pyrrolo-quinoline quinone (PQQ), were first described about 30 years ago. Quinoproteins were originally defined as proteins containing PQQ but this definition has since been broadened to include those proteins containing other types of quinone-containing prosthetic groups, and the X-ray structures of representatives of each type of quinoprotein have recently been published. This review is mainly concerned with the structure and function of the PQQ-containing methanol dehydrogenase, whose structure has been determined at high resolution, and related proteins. Their basic structure consists of a 'propeller' fold superbarrel made up of 8-sheet 'propeller blades' which are held together by novel tryptophan-docking motifs. In methanol dehydrogenase the PQQ in the active site is coordinated to a Ca2+ ion and is maintained in position by a stacked tryptophan and a novel 8-membered ring structure made up of a disulphide bridge between adjacent cysteine residues. This review describes these features and discusses them in relation to previously proposed mechanisms for this enzyme.

Alcohol Oxidoreductases↗
PubMed1998

Skin banking in the UK: the need for proper organization.

Skin banking was set up in Sheffield in 1991 to provide a readily available source of allograft material to be used both for research purposes and also as a means of providing immediate wound cover for major burns patients. Once skin was available, however, clinical demand for it both within and outside Sheffield, outstripped the resources to run the bank. Logistical difficulties were encountered in the day to day running of the bank. These revolved around shortage of staff available for harvesting, the relative lack of public awareness of skin donation, shortage of banked skin as the bank became more widely known and lack of space and finance to expand. The decision was made to transfer the now established skin bank to the National Blood Service where it now operates with staff and resources dedicated specifically to this purpose. Experience leads to the suggestion that there is a clinical need for allograft skin in the UK which is not being met at the present time. There is a need for dedicated properly resourced skin banks and for the Department of Health to introduce regulation, monitoring and inspection of skin bank facilities in order to safeguard standards.

Blood Banks↗