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Biomedical subjects

S K Ghosh

Publications and source records attributed to S K Ghosh.

At least 145 records · Page 8Linked to original sources
PubMed1989

Evidence for a new rotavirus subgroup in India.

Monoclonal antibodies specific for rotavirus subgroup 1 (SG1) and subgroup 2 (SG2) were used to analyse by enzyme immunoassay (EIA) the subgroups of human rotavirus isolates obtained from three different parts of India during the period September 1985 to July 1987. We identified one isolate which failed to react with either SG1 or SG2 specific monoclonal antibodies, although it reacted well with a monoclonal antibody specific for group A rotaviruses. This finding suggests that it belongs to a new rotavirus subgroup. Further, another isolate was found to belong to SG1 although it had a 'long' electropherotype.

Antibodies, Monoclonal↗
PubMed1989

Listeria monocytogenes meningitis in previously healthy adults.

A retrospective study of four sporadic cases of Listeria monocytogenes meningitis is reported. Contrary to the conventional epidemiology these patients were adults who were not immuno-compromised. Although all four cases produced positive cerebrospinal fluid cultures, in three, listeria was not microscopically identified. Protein and glucose contents of cerebrospinal fluids were variable and all samples showed lymphocytic pleocytosis. All four had neutrophil leucocytosis in peripheral blood. The unwary may dismiss lymphocytic meningitis as being of 'viral' origin, thereby making an important diagnostic misjudgement of vital therapeutic importance. Intravenous ampicillin is the drug of first choice for treatment of listeria meningitis; third generation cephalosporins are ineffective.

Adult↗
PubMed1989

Recurrent pyogenic meningitis--a retrospective study.

Records of 17 patients who had two or more attacks of pyogenic meningitis were collected from eight centres in the United Kingdom for retrospective analysis. Thirteen patients had intracranial abnormality; of seven with head injury five produced cerebrospinal fluid rhinorrhoea. The first of the 28 attacks seen in these occurred between a few weeks and 12 years of the head injury. Pneumococci were identified in 25 episodes in cerebrospinal fluid. Of six patients without a history of head injury, one had 'spontaneous cerebrospinal fluid rhinorrhoea' and five had pathological changes of the ear. Various organisms were found in the cerebrospinal fluid during the 12 attacks in these five. Four of the 17 patients had primary complement deficiency (C7, C5, C4 and C3b inhibitor); 10 (possibly 11) of 16 attacks in these cases were due to Neisseria meningitidis. Routine radiological investigations including computerized tomography did not always identify the abnormality; radioactive cisternography can help to establish cerebrospinal fluid leak. All 58 episodes of pyogenic meningitis in these 17 patients with different underlying disease responded to conventional treatment with antibiotics without mortality and without undue morbidity. Surgical procedures in intracranial disease had variable success. Correction of complement deficiency is not practical at present. In some patients prophylaxis with antimicrobial drugs is the only method of preventing future attacks.

Adolescent↗
PubMed1989

Drug resistant P. falciparum in Madras (Tamil Nadu) and district Jabalpur (Madhya Pradesh).

WHO micro in vitro tests for chloroquine resistance in P. falciparum were carried out during November, 1987 in Madras city, Tamil Nadu and in Kundam PHC of Jabalpur district, Madhya Pradesh. Out of 6 samples tested from Madras city, 5 showed resistance to chloroquine. Likewise, out of 14 samples tested in Jabalpur, 12 (85.7%) showed resistance to chloroquine. All the 20 samples showed normal susceptibility to mefloquine.

Adolescent↗
PubMed1988

Purification and molecular identification of two protein methylases I from calf brain. Myelin basic protein- and histone-specific enzyme.

Two different molecular species of protein methylases I (S-adenosylmethionine:protein-arginine N-methyltransferase, EC 2.1.1.23), one specific for myelin basic protein (MBP) and the other for histone, have been purified from calf brain to near homogeneity, as discerned by nondenaturing polyacrylamide gel electrophoresis. Although both methylases share some common properties, such as utilization of S-adenosyl-L-methionine as the methyl donor and methylation of protein-bound arginine residues, they are distinctly different from each other in molecular weight and in catalytic, as well as the immunological, properties. The MBP-specific protein methylase I (approximately 500 kDa) methylates MBP preferentially (Km = 2 X 10(-7) M) and histone to a much lesser extent (Km = 1 X 10(-4) M), while the histone-specific methylase I (approximately 275 kDa) methylates histone only. Both methylases exhibit two major subunit bands on sodium dodecyl sulfate-polyacrylamide gel electrophoresis: 100 and 72 kDa for the MBP-specific and 110 and 75 kDa for the histone-specific. At 0.5 mM p-chloromercuribenzoate, about 50% of the MBP-specific enzyme remained as active, while most of the histone-specific enzyme activity was lost. In 2 mM guanidine HCl, approximately 90% of the former enzyme activity remained while nearly complete inactivation of the latter enzyme was observed. The enzymes also exhibited quite different inactivation profiles toward high temperature (45-65 degrees C); MBP-enzyme was stable up to 50 degrees C and was rapidly inactivated at higher temperatures with an inflection point at about 57 degrees C. However, under the identical conditions, histone-enzyme was inactivated progressively and linearly in the same temperature range. Finally, Western immunoblot analysis of polyclonal antibodies directed against either enzyme exhibited no cross-reactivity with the other.

Animals↗
PubMed1988

Genetic analysis fo the mycobacillin biosynthetic pathway in Bacillus subtilis B3.

Twelve mycobacillin-negative (My-) mutants of Bacillus subtilis B3 were isolated from an auxotrophically tagged mycobacillin producer organism. In whole-cell fermentations of some of these My- mutants a penta- and a nonapeptide accumulated; these peptides were also obtained in a cell-free system in which a new tripeptide was also detected. The amino acid composition, N- and C-terminal residues and amino acid sequence of these peptides agreed with those of equivalent segments of the mycobacillin molecule. The mycobacillin-synthesizing enzyme can be divided into three fractions that catalyse different steps in biosynthesis, and the defective enzyme fractions in the various mutant strains were identified by reconstitution experiments in vitro. The defects were further pin-pointed in mutant enzyme fractions by an ATP in equilibrium Pi exchange reaction and also by cell-free synthesis involving the use of membrane-bound enzyme. The defects so identified indicated the formation of tri-, penta- and nonapeptides as intermediates in the mycobacillin biosynthetic pathway.

Amino Acids↗
PubMed1987

Idiotype-specific T lymphocytes responsible for the selection of somatic variants of a B cell hybrid.

A B cell hybrid (2C3E1), which when cultivated in vitro stably expresses a serologically defined private idiotype on the cell surface, undergoes a somatic variation which culminates in the generation of idiotype-negative variants when propagated as a tumor in syngeneic BALB/c mice. Lyt-1+ and Lyt-2- BALB/c T cells derived from appropriately primed spleen cells when co-cultured with 2C3E1 tumor cells in vitro are responsible for the generation or selection of the idiotype-negative tumor variants. The idiotype-specific effector T cells responsible for the variant production in vitro and in vivo are triggered either by viable or irradiated 2C3E1 tumor cells, but not by soluble idiotype-positive monoclonal antibody secreted by the tumor. The idiotype-positive antibody did stimulate the production of the effector T cells when the soluble protein was covalently linked to the plasma membrane of BALB/c spleen cells, but not when the idiotype-positive protein was presented on allogeneic C57BL/6 spleen cells. A single exposure of spleen cells to 2C3E1 cells in vivo was sufficient to prime the idiotype-specific T cells, but the frequency and reproducibility of variant selection increased when the in vivo primed effector T cells were restimulated by irradiated 2C3E1 cells in vitro prior to co-cultivation with the wild-type 2C3E1 cells. The initial variant B cell lines could be segregated into several different phenotypes. However, after extensive cultivation either in vitro or after repeated transfer in vivo, all of the variant cell lines acquired a single stable phenotype that was characterized by the loss of both the surface and secreted idiotype marker and antigen-binding activity associated with the wild-type 2C3E1 cells.

Animals↗
PubMed1987

Heat sensitivity and membrane properties of metastasizing and non-metastasizing rat mammary tumors.

Paired lines of metastasizing and non-metastasizing transplantable rat mammary tumors were studied for their sensitivity to hyperthermia. The metastasizing TMT-081 and SMT-2A tumors were markedly more sensitive to heat injury as measured by tumor growth delay than were their non-metastatic counterparts MT-100 and MT-W9B. The metastasizing MT-081 tumor was also significantly more sensitive than the SMT-2A tumor. The differences in heat sensitivity were not the result of differences in intra-tumor temperatures attained during water bath heating. A more likely explanation for the variable response obtained with these tumors after heat treatment may be the inherent differences in stability and composition of their cellular membranes, particularly the plasma membrane.

Adenocarcinoma↗
PubMed1987

Photogrammetric technique applied to anthropometric study of hands.

Being concerned with physical anthropometric dimensions to explore avenues of research on hands and their working strategies, a research study was made to develop a suitable method by using available photogrammetric resources. The paper discusses the optimums of details found by this study, viz., the use of a Wild C-40 stereometric camera (for obtaining stereoscopic photographs) and the use of a Wild A7 stereorestitution instrument equipped with digital data acquisition accessories (for obtaining all dimensional information). Three-dimensional data at 21 specific points and for nine specific distances were obtained on each hand of ten persons. Test observations indicate, inter alia, a dimensional accuracy of the order of +/- 0.3 mm obtainable through the working system. Cartographic presentations made in support of the digital data are found to be of help. This also permits to obtain additional data as may be necessary at times. Photogrammetry has the advantage of reducing and maintaining to a minimum all sorts of manipulations necessary in such studies.

Anthropometry↗
PubMed1987

Expression of mu and gamma 1 membrane forms of immunoglobulin segregate in somatic cell hybrids.

In the present investigation, we have utilized the somatic cell hybridization technique to generate an experimental model for studying the differential expression of membrane (mIg) and secreted (sIg) forms of immunoglobulin that characterize different stages of B cell development. We describe here that fusion of the dextran-binding myeloma, MOPC 104E (mu, lambda 1) and the phthalate-binding B cell hybridoma, 2C3E1 (gamma 1, kappa) results in the formation of antigen-specific, double hybrids (tribrids) that coexpress both parental secreted forms of Ig but express only one of the two possible membrane forms of immunoglobulin (Ig). This segregated expression of membrane Ig is a new and unexpected finding that has been substantiated here by both immunological and biochemical methods. Analysis by SDS-containing polyacrylamide gels (SDS-PAGE) reveals distinct and characteristic migration patterns for each of the four Ig heavy chains in the tribrids (mu membrane, mu secreted, gamma 1 membrane and gamma 1 secreted). Immunochemical analysis of the immunoglobulin from the tribrids confirms the coexpression of both secreted forms of immunoglobulin in most of the tribrid lines tested and indicates that about 30% of the tribrids express only phthalate-specific gamma 1 membrane Ig, while 38% express only dextran-binding mu membrane Ig. About 30% of the tribrids secrete both antibodies but express no membrane form and less than 1% are non-secretors. Approximately 2% initially express both membrane forms of Ig, as determined by immunocytoadherence assay using appropriate target cells but subsequently express only one membrane form during propagation in vitro. SDS-PAGE analysis of surface labeled tribrids confirms that in tribrids expressing membrane Ig, only a single mIg is synthesized. These results suggest that the expression of the secreted and membrane forms of immunoglobulin are separately regulated and the tribrids represent a model with which to study the mechanisms involved in the regulation of each structurally distinct immunoglobulin form.

Animals↗
PubMed1987

Isolation and identification of gram negative bacteria from raw baled cotton and synthetic textile fibers with special reference to environmental GNB and endotoxin concentrations of textile mill.

The objective of this study was to examine the gram-negative bacterial (GNB) content of Indian raw baled cotton fibers and to compare with the U.S. cottons. Airborne endotoxin also was estimated in the different work places of the mill. On comparison with data on U.S. cottons, GNB content was found to be as high as in U.S. cottons. Moreover, endotoxin concentration of cardroom dust from an Indian cotton mill was found to be significantly (P less than 0.01) higher than in the research laboratory of the same cotton mill as well as in the cardroom of a synthetic mill.

Air Microbiology↗
PubMed1986

Role of ATP and enzyme-bound nascent peptides in the control of elongation for mycobacillin synthesis.

The enzyme fraction A, a constituent of the three-fraction (A, B and C) enzyme complex mycobacillin synthetase, elongated tri- and tetra-peptides, under enzyme-bound conditions, to tetra- and penta-peptides respectively in the presence of the 'next' amino acid (in the mycobacillin sequence). The enzyme fraction B synthesized hexapeptide from free pentapeptide and the next amino acid, but synthesized heptapeptide from hexapeptide only under enzyme-bound conditions in the presence of the next amino acid. Similarly, the enzyme fraction C synthesized decapeptide from free nonapeptide in the presence of the next amino acid, but undecapeptide only from enzyme-bound decapeptide in the presence of the next amino acid during the elongation process. The Km values for the initiating reactions for each of the three enzyme fractions were 6-7-fold lower than those for the succeeding reactions catalysed by each of the enzyme fractions. The specificity of the initiation and elongation is discussed in the light of these findings.

Adenosine Triphosphate↗
PubMed1986

Characterization of three-fraction mycobacillin synthetase.

Mycobacillin synthetase lacks aspartic acid racemase, alanine racemase and glutamic acid racemase activities. The enzyme also does not respond to ATP-[32P]Pi exchange, nor does it catalyse the antibiotic synthesis in presence of amino acids of configuration opposite to that present in the molecule. Preincubation with optical isomers of opposite configuration inhibited the ATP-[32P]Pi exchange reaction to the extent of 60-90%. None of the three fractions of mycobacillin synthetase contained a pantothenic acid arm. Two molecules of ATP are required to synthesize one peptide bond of mycobacillin. Intermediate peptides of mycobacillin are not covalently linked to the three-fraction mycobacillin synthetase.

Adenosine Triphosphate↗