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Biomedical subjects

D K Banerjee

Publications and source records attributed to D K Banerjee.

At least 37 records · Page 2Linked to original sources
PubMed1993

Activity of sparfloxacin against Mycobacterium leprae measured by the proportional bactericidal test.

The activity of 25 mg/kg and 50 mg/kg sparfloxacin was measured against Mycobacterium leprae in normal (immunocompetent) mouse foot pads by the proportional bactericidal test. This was compared with the action of 25, 50, and 150 mg/kg ofloxacin by the same method. Sparfloxacin, at both concentrations, was found to be strongly bactericidal by this method, comparable to 150 mg/kg ofloxacin.

Animals↗
PubMed1992

Monoclonal antibody to amphomycin. A tool to study the topography of dolichol monophosphate in the membrane.

Understanding the topographical orientation of dolichol monophosphate (Dol-P) in the membrane of the endoplasmic reticulum (ER) is of utmost importance for studying the regulation of asparagine-linked protein glycosylation in eukaryotic cells. This was practically impossible due to the nonavailability of a suitable probe. Recent studies on the specific interaction between a lipopeptide, amphomycin, and Dol-P, provided an insight to develop a monospecific antibody to amphomycin which could recognize the amphomycin-Dol-P complex in order to detect Dol-P immunocytochemically in the ER membrane. We report herein the successful production of a monoclonal antibody to amphomycin. The antibody belongs to the IgG+IgM subclasses and is specific for amphomycin when analyzed by the enzyme-linked immunoassay and immunoblot procedures. The antibody recognizes with equal potency both the native amphomycin and also mild acid-hydrolyzed amphomycin from which N-terminal fatty acylated aspartic acid has been removed. Preincubation of amphomycin with the antibody partially reduced the inhibitory action of amphomycin on dolichol phosphate mannosyltransferase (EC 2.4.1.83). Furthermore, exposure of capillary endothelial cells to amphomycin, followed by the monoclonal antibody to amphomycin, followed sequentially by staining with FITC-conjugated goat anti-mouse IgG and examination under a fluorescent microscope gives intense fluorescence at the perinuclear region of the cell with a structure reminiscent of the ER.

Amino Acid Sequence↗
PubMed1992

Expression of blood clotting factor VIII:C gene in capillary endothelial cells.

The essential role of Factor VIII:C (FVIII:C, anti-hemophilia factor A) as a cofactor for Factor IXa-dependent activation of Factor X has been established. In this paper, we describe that capillary endothelial cells from bovine adrenal medulla express active FVIII:C gene. Accumulation of FVIII:C in conditioned media from an 8-day-old culture is approximately twice as high as that stored in the cell when immunoprecipitated FVIII:C was analyzed for its ability to convert Factor X to Factor Xa. Analysis of [35S]methionine-labeled and immunoprecipitated FVIII:C from cells or conditioned media on SDS-PAGE under fully denatured conditions indicated that the newly synthesized FVIII:C consists of heavy chain of M(r) 200,000 and light chain of M(r) 46,000. The secreted FVIII:C in the non-reduced condition however, has a molecular weight of 270,000 which suggests that in native protein, the heavy and light chains are held together by S-S bonds. Furthermore, susceptibility of the immunoprecipitated FVIII:C to N-glycanase digestion establishes that the endothelial cells derived FVIII:C contains asparagine-linked carbohydrate side chains.

Adrenal Medulla↗
PubMed1992

The reliability of urinary cytology in the detection of tumours of urinary bladder.

Detection of urinary bladder tumours by cytological examination of urine was carried out on 193 patients suffering from haematuria. The patients comprised 149 new cases and 44 follow-up cases previously diagnosed as bladder cancer. Urinary bladder malignancy was detected in 72 of new cases and 20 of follow-up cases by cytological examination of urine. Reliability of the findings was checked by histopathological examination of the biopsy material removed from bladder by cystoscopy which detected malignancy in 84 of new cases and 16 of follow-up cases. Thus the sensitivity of cytological examination of urine in detecting bladder malignancy was 92% and specificity of 88%. False positive result was 4% and false negative result was 12%.

Adenocarcinoma↗
PubMed1992

An experimental study to evaluate the bactericidal activity of ofloxacin against an established Mycobacterium leprae infection.

The bactericidal effect of a new quinolone, ofloxacin (OFLO), was determined on an established Mycobacterium leprae infection in nude mice. Various drug regimens, including combinations of drugs, were examined for different treatment periods. OFLO and rifampin (RMP) individually failed to produce significant killing after treatment with a single large dose. However, when single large doses of OFLO and RMP were given in combination, a 100-fold reduction in viability was achieved. For a longer period of treatment both of these drugs, at lower doses, produced a moderate reduction in viability. The addition of dapsone to the lower dose of OFLO resulted in a significant reduction in viability, while lower doses of RMP and OFLO together produced a moderate reduction in viability.

Animals↗
PubMed1991

Characterization of the heat shock response in Mycobacterium bovis BCG.

We have for the first time characterized the heat shock response in mycobacteria both at the level of transcription, by RNA extraction, Northern (RNA) blotting, and hybridization with gene-specific probes for the Mycobacterium tuberculosis 65- and 71-kDa heat shock proteins (HSPs), and at the level of translation, by [35S]methionine labelling, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and autoradiography. We observed increased synthesis of 40-, 65-, 71-, and 90-kDa proteins, which appear to be major HSPs in mycobacteria. The 40-, 71-, and 90-kDa HSPs are coordinately regulated in terms of temperature requirements and kinetics of induction but differ in the levels of expression. The 65- and 71-kDa HSPs are differentially regulated in response to temperature, with different kinetics and levels of induction. mRNA transcript sizes for the 71-, 65-, 40-, and 30-kDa proteins were found to be broadly consistent with DNA sequence open reading frames. A maximum increase of about 69-fold in the levels of mRNA for the 71-kDa HSP after 45 min of heat shock at 45 degrees C was observed, whereas the 65-kDa HSP mRNA increased only 5-fold. It was also found that in M. bovis BCG, as in Escherichia coli, a major control mechanism of the heat shock response is operative at the level of transcription. An ability to characterize the heat shock response in mycobacteria provides an experimental model with which to study environmentally regulated gene expression and an opportunity to identify virulence genes, which may coregulate as part of the heat shock regulon.

Blotting, Northern↗
PubMed1991

Insulin and IGF-1 manifest differential effects in a clonal capillary endothelial cell line.

125I-insulin (10 fmoles) binding plus internalization (BI) to a clonal capillary endothelial (CE) cell line reached to a steady state after 20 min. Acid-washed fraction accounted for nearly half of the total specifically-bound hormone. Dissociation constants (Kd) for insulin-surface receptor in acid-extractable fraction were 0.04 nM (high affinity) and 4.7 nM (low affinity) with a total number of 210,000 high affinity receptors per cell. When 125I-labeled IGF-1 (15 fmoles) was incubated similarly, BI reached only a quasi-equilibrium by 6 min and continued to increase thereafter. 2-Deoxyglucose transport in these cells was stimulated by insulin whereas IGF-1 inhibited its entry.

Animals↗
PubMed1990

Role of extracellular signaling on endothelial cell proliferation and protein N-glycosylation.

In vitro studies of angiogenic phenomenon have been limited due to nonavailability of a simple and biologically relevant model of the capillary wall. Recent development of a capillary endothelial cell line from the vascular bed of bovine adrenal medulla made us to study the effect of heparin, thrombin, thyroxine, glucagon, insulin, and phorbol myristate acetate (PMA) on the proliferative and metabolic activities such as glycosylation of asparagine-linked glycoproteins of these cells in culture. Out of six different agents studied here, only heparin, thrombin, and thyroxine reduced the doubling time of these cells by 24 hr with no observed morphological abnormality. Glucagon, showed marginal reduction in the cell doubling time. By contrast, insulin and PMA enhanced the doubling time. Insulin treatment though induced the S phase of cell cycle but it blocked the cells entry into the G2 + M phase. PMA arrested the cells in G0/G1 phase. The cellular response to protein N-glycosylation is increased in the presence of thyroxine, insulin, and thrombin and the effect is dose dependent. Further analysis on SDS-PAGE indicated that glycosylation of 80-120 kDa and 43 kDa glycoprotein species are enhanced when these cells are treated with insulin and thrombin. Glycopeptide generated from these glycoproteins suggested that they all carry "high mannose" and "complex" type oligosaccharide chains attached to their protein core.

Animals↗
PubMed1990

Time-related decrease of substance P and CGRP in central and peripheral projections of sensory neurones in Mycobacterium leprae infected nude mice: a model for lepromatous leprosy in man.

We have previously shown the depletion of cutaneous calcitonin gene-related peptide (CGRP)- and substance P-containing nerves in human leprosy. The aims of this study were to investigate the temporal effects of leprosy on nerves in skin and spinal cord. Tissues were taken from nude mice, 6 and 12 months after inoculation of Mycobacterium leprae into the hind footpads, and from age-matched controls. Sections were immunostained with antisera to substance P or CGRP. After 6 months of infection, substance P- and CGRP-immunoreactive nerves were reduced in skin from all body areas; by 12 months, the reduction was substantially greater. In the spinal cord, sensory fibres immunoreactive for substance P had decreased compared with controls at 6 and 12 months [by 60 per cent (0.022 mm2) and 80 per cent (0.048 mm2), respectively, P less than 0.001], as with CGRP [30 per cent (0.018 mm2) (P less than 0.02) and 40 per cent (0.028 mm2) (P less than 0.01), respectively]. CGRP immunoreactivity was completely absent in motor neurones after 12 months of infection. Loss of CGRP- and substance P-immunoreactive fibres in skin and spinal cord, and CGRP in motor neurones is in accord with impaired pain sensation and muscle weakness in leprosy.

Animals↗
PubMed1990

Effect of simultaneous administration of interferon-gamma and chemotherapy against Mycobacterium leprae in experimental infection in nude mice.

The possibility of synergy between immunotherapy with recombinant interferon-gamma (IFN-gamma) and chemotherapy with rifampin (RMP) and dapsone (DDS) against Mycobacterium leprae was examined in nude mice. IFN-gamma alone failed to show any effect on the growth of M. leprae in the nude mouse foot pad. No synergy was demonstrable between DDS, either at 0.0001% or at 0.001%, and IFN-gamma. A subinhibitory level of RMP with IFN-gamma was also ineffective, but RMP at 0.006% with IFN-gamma produced a statistically significant enhancement of killing (26-fold) when compared with RMP at 0.006% only. It should be emphasized, however, that results obtained in the immunodeficient nude mouse model may not be comparable to those which might have been given by lepromatous leprosy patients.

Animals↗
PubMed1989

Amphomycin inhibits mannosylphosphoryldolichol synthesis by forming a complex with dolichylmonophosphate.

The inhibitory effect of the lipopeptide antibiotic amphomycin on the mechanism of mannosylphosphoryldolichol biosynthesis by calf brain rough endoplasmic reticulum membranes has been studied extensively. Calf brain rough endoplasmic reticulum membranes when incubated with varying concentrations of GDP-mannose in the presence and absence of amphomycin showed no significant difference in apparent Km for GDP-mannose (1.08 and 1.37 microM, respectively). However, the Vmax was reduced to 0.17 pmol/mg protein/min in the presence of amphomycin as compared with 1.86 pmol/mg protein/min in its absence. On the other hand, when mannosylphosphoryldolichol synthase activity was measured in the presence of amphomycin and as a function of dolichylmonophosphate (Dol-P) concentrations, the shape of the substrate velocity curve changed from a rectangular hyperbola to a sigmoid. The Hill coefficients (n) for this reaction were calculated to be 2.02 and 1.22 in the presence and absence of the antibiotic and the corresponding Km values for Dol-P were found to be 333 and 47.3 microM, respectively. In separate experiments when radiolabeled antibiotic was reacted with Dol-P in the presence of Ca2+, a complex was formed. The complex formation was dependent on both Ca2+ in the reaction mixture and fatty acid residue on the antibiotic. Similar complex formation was also observed with undecaprenylmonophosphate. No such complex, however, was formed with dolichylpyrophosphate, with undecaprenylpyrophosphate, or with their free alcohols (dolichol or undecaprenol). Furthermore, when an equimolar mixture of Dol-P and phosphatidylserine was reacted with the antibiotic under identical conditions, the complex formation was observed selectively with Dol-P. These data demonstrated that amphomycin interacted with the active site of the glycosyl-carrier lipid (Dol-P), thereby preventing its participation at the enzymatic reaction.

Animals↗
PubMed1989

Interleukin-1 production by human monocytes in ageing and disease.

Interleukin-1 mediates the febrile response which is often said to be reduced in the elderly. Interleukin-1 production by monocytes cultured in vitro and stimulated with bacterial lipopolysaccharide was measured. Three groups of subjects were studied; 40 normal young, 33 well elderly and 40 elderly with a history of repeated infection. No difference in interleukin-1 secretion was found between the groups. When the group with recurrent infection was subdivided into those with a history of fever and those with no record of fever accompanying their infection, the group without fever produced significantly less interleukin-1 (p = 0.035).

Adolescent↗