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Biomedical subjects

A Ghosh

Publications and source records attributed to A Ghosh.

At least 127 records · Page 7Linked to original sources
PubMed2000

Cloning, expression, and sequence analysis of the gene encoding the alkali-stable, thermostable endoxylanase from alkalophilic, mesophilic Bacillus sp. Strain NG-27.

Alkalophilic Bacillus sp. strain NG-27 produces a 42-kDa endoxylanase active at 70 degrees C and at a pH of 8.4. The gene for this endoxylanase was cloned and sequenced. The gene contained one open reading frame of 1,215 bases. An active site characteristic of the family 10 beta-glycanases was recognized between amino acids 303 and 313, with the active glutamate at position 310. Though highly thermostable, the enzyme contains no cysteine residue.

Amino Acid Sequence↗
PubMed2000

Comparison of anthropometric characteristics between normotensive and hypertensive individuals among a population of Bengalee Hindu elderly men in Calcutta, India.

A comparative investigation of 99 normotensive and 111 hypertensive Bengalee Hindu elderly men (aged 55 years and above) of Kalighat, South Calcutta, India, was undertaken to study differences in levels of adiposity, body fat distribution and body composition between these two groups. Results revealed that there were significant differences between normotensive (NT) and hypertensive (HT) subjects in the mean values for weight (p < 0.05), body mass index (BMI, p < 0.01); waist (p < 0.001) and hip circumferences (p < 0.05); waist-hip ratio (WHR, p < 0.001), conicity index (CI, p < 0.01) and fat free mass (FFM, p < 0.001). Percentile distributions for all these variables and indices showed consistently higher values among the HT patients as compared with NT subjects. However, the frequency of obesity (BMI > or = 25) was similar (NT = 6.1%, HT = 11.7%) in both groups. Thus, these results indicated that there existed significant differences in central adiposity and FFM between NT and HT subjects although their level of obesity was similar. Hypertensive individuals have significantly enhanced levels of central body fat distribution.

Aged↗
PubMed2000

Psychiatric morbidity of a rural Indian community. Changes over a 20-year interval.

BACKGROUND: Cross-sectional studies give no indication of the changes that may occur in the mental health status of a community in course of times. Studies should be designed to assess these changes. AIMS: To assess the changes, if any, in the prevalence of mental disorders in a rural community after an interval of 20 years in the context of its changing socio-economic conditions. METHOD: A door-to-door survey of the prevalence of psychiatric morbidity in two villages was conducted by a team of psychiatrists. The survey was repeated after 20 years by the same team and by the same method. Changes in the mental health status of the community were compared. RESULTS: Total morbidity per 1000 fell from 116.8 to 105.2. Morbidity in men fell from 86.9 to 73.5 per 1000 and in women from 146.8 to 138.3 per 1000. Rates of anxiety, hysteria and phobia had fallen dramatically and those of depression and mania had risen significantly. CONCLUSION: The level of psychiatric morbidity showed no statistically significant change. The morbidity pattern (relative proportion of type of morbidity), however, showed some interesting changes. Similar studies should be done on a larger sample.

Adolescent↗
PubMed2000

Impact of diazepam on pineal-adrenal axis in an avian model.

Diazepam, a benzodiazepine derivative, better known as a melatonin blocker in mammals, was injected into pigeons at a dose of 3 mg/kg body weight/day for 1 h, 1 day, 7 days and 15 days. This was done to investigate whether diazepam-induced changes in the pineal gland were reflected in the functioning of the adrenal gland. The results indicated that diazepam caused inhibition of pineal function and the degree of inhibition was very much time dependent. In addition, the pineal gland was unable to modulate the adrenomedullary hormonal titre yet it considerably influenced the physiology of the adrenal cortex.

Adrenal Glands↗
PubMed2000

The Cochrane Library: a resource for current reviews of clinical evidence.

The Cochrane Library is a tool for physicians and other health care practitioners seeking evidence to inform their decisions. The systematic reviews provide a high-quality synthesis of the current literature, saving time for busy people. To make the library more user-friendly, the collaboration plans to produce a consumer summary for each topic in the Database of Systematic Reviews and a cancer library aimed at the general public. In contrast to some of the questionable health-related resources on the Web, the Cochrane Library is an authoritative reference that can help physicians with everyday treatment decisions. The collaboration's commitment to keeping its resources up to date through vigorous support of reviewers should ensure that it remains a valuable Internet tool for physicians.

Databases as Topic↗
PubMed2000

Aspiration vs nonaspiration technique of cytodiagnosis--a critical evaluation in 160 cases.

The two sampling techniques were studied in 160 randomly selected cases of superficial swellings in various sites of the body. They were sampled by fine needle aspiration (FNA) and by non-aspiration (NA) (a needle without application of aspiration pressure). Cell samples were cytologically assessed and critically evaluated using five objective parameters. Contamination with blood was more in lymphnode, thyroid and liver lesions in aspiration smears than NA smears and values were statistically significant. Similarly when compared for the degree of cellular trauma and cellular degeneration statistically significant better results were obtained by nonaspiration technique for lymphnode lesions. Regarding amount of cellular material obtained by FNA, statistical significant better results were found for breast lesions only. Statistically significant better maintenance of architecture was observed only for thyroid lesions by NA technique. Better average scores were observed by NA technique for lymphnode and thyroid only. Categorizing all the smears obtained by FNA & NA on the basis of their scores according to predetermined criteria, greater number of diagnostically adequate specimens were obtained by FNA than by NA but the number of diagnostically superior specimens obtained by NA technique was found to be more than that by FNA. The difference was found to be statistically significant. However the number of inadequate smears was also more by NA technique than by FNA technique.

Biopsy, Needle↗
PubMed2000

Cervical cancer--the impact of clinical presentation, health and race on survival.

This study evaluated the association of race, comorbid illness, insurance status, and other prognostic factors on treatment and survival of patients with invasive carcinoma of the cervix, using as its methodology a retrospective study of patients with invasive carcinoma of the cervix treated from 1991 to 1998 at the University of Maryland. Of 161 such patients, 153 met the study criteria. Of these 153 women, 83 (54%) were African Americans and 70 (46%) were white. The mean (+/- SE) age of African American women was 52 +/- 1.8 years and that of white women was 50 +/- 1.8 years. African American women were more likely to present with stages II-IV disease (P = 0.01) and, as a consequence, underwent radiation therapy rather than surgery (P = 0.04). The survival of African American women with stage I-II disease was significantly lower than for white women. In the final regression model, stage III-IV disease (hazard ratio 3.2, 95% (CI 1.7, 6.1) African American race, (hazard ratio 1.9; 95% CI 1.0, 3.3) and comorbid illnesses (hazard ratio 2.3; 95% CI 1.3-4.0) were associated with poor survival. Adverse outcomes of African American women with cervical cancer persist after adjustment for stage of disease and other factors and are particularly apparent in stage I-II disease. The role of comorbid illness is deserving of further study.

Black or African American↗
PubMed1999

C-H.O hydrogen bonds in minor groove of A-tracts in DNA double helices.

Analysis of available B-DNA type oligomeric crystal structures as well as protein-bound DNA fragments (solved using data with resolution <2.6 A) indicates that in both data sets, a majority of the (3'-Ade) H2..O2(3'-Thy/Cyt) distances in AA.TT and GA.TC dinucleotide steps, are considerably shorter than their values in a uniform fibre model, and are smaller than their optimum separation distance. Since the electropositive C2-H2 group of adenine is in close proximity of the electronegative keto oxygen atoms of both pyrimidine bases in the antiparallel strand of the double-helical DNA structures, it suggests the possibility of intra-base-pair as well as cross-strand C-H..O hydrogen bonds in the minor groove. The C2-H2..O2 hydrogen bonds within the A.T base-pairs could be a natural consequence of Watson-Crick pairing. However, the close cross-strand interactions between the bases at the 3'-ends of the AA.TT and GA.TC steps arise due to the local sequence-dependent geometry of these steps. While the base-pair propeller twist in these steps is comparable to the fibre model, some of the other local parameters such as base-pair opening angle and inter-base-pair slide show coordinated changes, leading to these shorter C2-H2..O2 distances. Hence, in addition to the well-known minor groove hydration, it appears that favourable C2-H2..O2 cross-strand interactions may play a role in imparting a characteristic geometry to AA.TT and GA.TC steps, as well as An.Tn and GAn.TnC tracts, which leads to a narrow minor groove in these regions.

Base Pairing↗
PubMed1999

The nature of the catalytic domain of 2'-5'-oligoadenylate synthetases.

2'-5'-Oligoadenylate (2-5(A)) synthetases are a family of interferon-induced enzymes that are activated by double-stranded RNA. To understand why, unlike other DNA and RNA polymerases, they catalyze 2'-5' instead of 3'-5' phosphodiester bond formation, we used molecular modeling to compare the structure of the catalytic domain of DNA polymerase beta (pol beta) to that of a region of the P69 isozyme of 2-5(A) synthetase. Although the primary sequence identity is low, like pol beta, P69 can assume an alphabetabetaalphabetabetabeta structure in this region. Moreover, mutation of the three Asp residues of P69, which correspond to the three catalytic site Asp residues of pol beta, inactivated the enzyme without affecting its substrate and activator binding capacity, providing further credence to the concept that this region is the catalytic domain of P69. This domain is highly conserved among all 2-5(A) synthetase isozymes. Biochemical and mutational studies demonstrated that dimerization of the P69 protein is required for its enzyme activity. However, a dimer containing a wild type subunit and an inactive catalytic domain mutant subunit was also active. The rate of catalysis of the heterodimer was half of that of the wild type homodimer, although the two proteins bound double-stranded RNA and ATP equally well.

2',5'-Oligoadenylate Synthetase↗
PubMed1999

Isolation of a taxol-resistant Leishmania donovani promastigote mutant that exhibits a multidrug-resistant phenotype.

We raised a strain of Leishmania donovani in the laboratory that was resistant to 500 nM taxol. The IC50 of the wild-type strain for taxol was 35 nM and that of the taxol-resistant strain (T-500) was 1 microM. The T-500 strain exhibited a Mdr phenotype; it was also resistant to other unrelated drugs like vinblastine, adriamycin and the commonly used antimonial drugs pentostam and glucantime. Verapamil (20 nM), a calcium channel blocker, was found to reverse the resistance of T-500 to taxol. Acquired resistance to taxol has been reported to be mediated by alterations involving tubulin in cancer cells. Thus polymerisation assays with tubulin fractions in wild-type versus taxol-resistant cells (T-500) were performed in vitro. The tubulin fraction from T-500 was more resistant to in vitro polymerisation than the tubulin isolated from the wild-type, suggesting that this is one means by which the parasite may acquire resistance to taxol.

Animals↗
PubMed1999

Construction of a recombinant live oral vaccine from a non-toxigenic strain of Vibrio cholerae O1 serotype inaba biotype E1 Tor and assessment of its reactogenicity and immunogenicity in the rabbit model.

The disease cholera is an important cause of mortality in many developing countries. Though it can be controlled through improved sanitation, this goal is not easily attainable in many countries. Development of an efficacious vaccine offers the best immediate solution. A new oral candidate vaccine has been constructed from a non-toxigenic strain of Vibrio cholerae E1 Tor, Inaba, which is not only devoid of the cholera toxin (CT) virulence cassette but also is completely non-reactogenic in rabbit ileal loop assay. The strain, however, had toxR and tcpA genes. Through a series of manipulations, the ctxB gene of V. cholerae, responsible for the production of the 'B' subunit of the cholera toxin (CTB) was introduced into the cryptic hemolysin locus of the strain. The resulting strain, named vaccine attempt 1.3 (VA1.3), was found to be able to produce copious amounts of CTB. In the RITARD model this strain was found to be non-reactogenic and provided full protection against the challenge doses of both V. cholerae O1, classical and E1 Tor. In the immunized rabbit it invoked significant levels of anti-bacterial and anti-toxin immunity.

Administration, Oral↗
PubMed1999

Localization of DnaK and GroEL in Vibrio cholerae.

Though the GroEL and DnaK heat shock proteins are well characterized in prokaryotes, only scanty and controversial information exist about their cellular localization. In the present study, the localization of the heat shock proteins DnaK and GroEL in normal and heat shocked cells of Vibrio cholerae, was investigated both by immunogold labeling of ultrathin sections and biochemical methods. Much of the DnaK was found to be localized at the inner membrane in unstressed cells, most probably at the Bayer's adhesion sites. Data suggested that upon heat shock, the DnaK associated with the membrane continued to remain there, but the newly synthesized DnaK appeared mostly in the cytoplasm. GroEL in both stressed and unstressed cells was found mainly in the cytoplasm.

Bacterial Proteins↗
PubMed1999

Isolation of a laminin-binding protein from the protozoan parasite Leishmania donovani that may mediate cell adhesion.

Extracellular matrix (ECM)-binding proteins on the surface of Leishmania are thought to play a crucial role in the onset of leishmaniasis, as these parasites invade mononuclear phagocytes in various organs after migrating through the ECM. In a previous report, we presented several lines of evidence suggesting that Leishmania has a specific receptor for laminin, a major ECM protein, with a Kd in the nanomolar range. Here we describe the identification, purification and biochemical characterization of the Leishmania laminin receptor. When the outer membrane proteins of L. donovani were blotted on to nitrocellulose paper and probed with laminin, a prominent laminin-binding protein of 67 kDa was identified. The purified protein was isolated by a three-step process involving DEAE-cellulose, Con A (concanavalin A)-Sepharose and laminin-Sepharose affinity chromatography and was used to raise a monospecific antibody. The same protein was obtained when parasite membrane extracts were adsorbed to antibody affinity matrix and eluted with glycine. The affinity-purified protein bound to laminin in a detergent-solubilized form as well as after integration into artificial bilayers, and was subsequently characterized as an integral membrane protein. Metaperiodate oxidation and metabolic inhibition of glycosylation studies indicate the binding protein to be glycoprotein in nature and that N-linked oligosaccharides play a part in the interaction of laminin with the binding protein. Surface-labelled parasites attached to microtitre wells coated with laminin and the 67 kDa protein blocked the adhesion to laminin substrate. We propose that the 67 kDa protein is an adhesin involved in the attachment of Leishmania to host tissues.

Animals↗
PubMed1999

Enzymatic characteristics of recombinant medium isozyme of 2'-5' oligoadenylate synthetase.

P69 is an isozyme of the medium size class of human 2'-5' oligoadenylate synthetases. In this study, recombinant P69 was expressed and used for enzymological and structural investigations. Bacterially expressed P69 was inactive whereas the same protein expressed in insect cells was highly active. Whether this difference could be due to differential post-translational modifications of the protein was investigated. Mutations of appropriate residues showed that myristoylation of the protein was not necessary for enzyme activity. In contrast, inhibition of glycosylation of P69, by tunicamycin treatment of the insect cells, produced an enzymatically inactive protein. Recombinant P69 produced in insect cells was purified by affinity chromatography. It was a dimeric glycoprotein, very stable and completely dependent on double stranded (ds) RNA for activity. The enzyme catalyzed the non-processive synthesis of 2'-5'-linked oligoadenylate products containing up to 30 residues. 2'-O-Methylated dsRNA was incapable of activating P69 and a 25-base pair dsRNA was as effective as larger dsRNA. This expression system will be useful for large scale production of P69 and its mutants for structural studies.

2',5'-Oligoadenylate Synthetase↗
PubMed1999

Leishmania donovani: characterization and expression of ORFF, a gene amplified from the LDI locus.

The LD1 locus is a 27.5-kb region of chromosome 35 that is conserved among all species of Leishmania and is amplified in several different isolates. Here, we report the genomic distribution of ORFF, a gene from the LD1 region, and its expression at the RNA and protein levels in two Indian isolates of Leishmania donovani. In both of these isolates, ORFF was present as a single copy on chromosome 35. Densitometric analysis of ORFF mRNA abundance revealed relative abundance of 0.2 and 1.0 in AG83 and S-Lal, respectively. Antiserum against recombinant ORFF protein detected a protein of the predicted size ( approximately 34 kDa) in both strains. The protein is most abundant in mid-log-phase promastigotes and has a nuclear localization. The ORFF protein is preferentially expressed in L. donovani amastigotes but, in contrast, is expressed at higher levels in L. major promastigotes.

Animals↗