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Biomedical subjects

M Banerjee

Publications and source records attributed to M Banerjee.

At least 109 records · Page 6Linked to original sources
PubMed1991

Non-sporing anaerobes in hospital sepsis.

In comparison to normal controls, the non-sporing anaerobes were often isolated from orodental sepsis (42% to 44.4%), chronic suppurative otitis media (40%), septic abortion (40.3%), uterocervical wound (45.4%), vaginitis (50%) and cancer cervix (50%). This was true (40%) in perforating ulcers of foot in leprosy. These organisms were less frequently noted in abdominal (11%) and episiotomy (22.8%) wounds and leucorrhoea (33.3%). The role of non-sporing anaerobes was also suggested by the high percentage ratio of number of isolates to number of cases and by its primary isolation in moderate to heavy number. Barring the cases of cancer cervix, the aerobic bacteria were the most common (78.8% to 100%) in all other conditions.

Bacteria, Anaerobic↗
PubMed1990

Pyruvate-induced stimulation of nitrogenase activity in Aulosira fertilissima.

The effect of pyruvate on nitrogenase activity in the N2-fixing cyanobacterium Aulosira fertilissima has been studied. Addition of 0.01-1.0 mM concentrations of pyruvate to actively N2-fixing cultures stimulated the enzyme activity in light; the maximum stimulation was observed with 0.3 mM pyruvate. There was no detectable stimulation of nitrogenase activity in the dark. Addition of pyruvate had no effect on the growth rate. DCMU gradually inhibited nitrogenase activity, but supplementation of 0.3 mM pyruvate to such cultures restored normal activity. Furthermore, pyruvate-induced stimulation of nitrogenase activity was found to be stimulated by anaerobic conditions. The inactivation of nitrogenase activity by the addition of O2 was restored by pyruvate. From 14CO2 uptake studies it appears that the alga preferred to take up pyruvate even in the presence of 14CO2. Thus it appears that pyruvate is taken up and metabolized by the alga, which manifests the observed effects.

Carbon Dioxide↗
PubMed1990

Lung mechanics and airway reactivity in sheep during development of oxygen toxicity.

The causes of respiratory distress in O2 toxicity are not well understood. The purpose of this study was to better define the airway abnormalities caused by breathing 100% O2. Sheep were instrumented for measurements of dynamic compliance (Cdyn), functional residual capacity by body plethysmography (FRC), hemodynamics, and lung lymph flow. Each day Cdyn and FRC were measured before, during, and after the application of 45 min continuous positive airway pressure (CPAP) at 15 cmH2O. The amount of aerosol histamine necessary to reduce Cdyn 35% from baseline (ED35) was measured each day as was the response to aerosol metaproterenol. Cdyn decreased progressively from 0.083 +/- 0.005 (SE) 1/cmH2O at baseline to 0.032 +/- 0.004 l/cm H2O at 96 h of O2. Surprisingly, FRC did not decrease (1,397 +/- 153 ml at baseline vs. 1,523 +/- 139 ml at 96 h). The ED35 to histamine did not vary among days or from air controls. Metaproterenol produced a variable inconsistent increase in Cdyn. We also measured changes in Cdyn during changes in respiratory rate and static pressure-volume relationships in five other sheep. We found a small but significant frequency dependence of compliance and an increase in lung stiffness with O2 toxicity. We conclude that in adult sheep O2 toxicity reduces Cdyn but does not increase airway reactivity. The large reduction in Cdyn in O2 toxicity results from processes other than increased airway reactivity or reduced lung volume, and Cdyn decreases before the development of lung edema.

Animals↗
PubMed1990

Effect of metal chelators on thermoluminescence peaks of spinach chloroplasts and photosystem II particles: probing the water oxidation cycle with 8-hydroxyquinoline.

Inhibition of photosystem II (PS II) activity by 8-hydroxyquinoline (8-HQ) has been investigated in case of spinach chloroplasts and isolated photosystem II particles using the thermoluminescence technique. In presence of 8-HQ, water to methylviologen (MV) photoreduction in isolated chloroplasts is inhibited while the reduction of dichlorophenol indophenol is inhibited in both chloroplasts as well as in photosystem II particles. The activity can be restored fully by addition of diphenylcarbazide (DPC), suggesting that the donor side of water oxidation complex is affected. The changes in the thermoluminescence peaks indicate that the charge recombination processes involving S2 or S3 states of the Kok's cycle are probably affected by 8-HQ treatment.

Chelating Agents↗
PubMed1990

Chemical probes for water oxidation cycle of photosystem II: Part 2--Effect of histidine modifying reagent on thermoluminescence peaks of spinach chloroplasts.

A modification of water oxidation complex in spinach chloroplasts by rose bengal (RB), a known histidine modifying agent, has been studied using thermoluminescence (TL) technique. The changes in the TL profiles at low concentrations of the dye are explained on the basis of alterations in the protein dynamics while those at higher concentrations of the dye are related to the oxidation of histidine residues.

Chloroplasts↗
PubMed1989

Cytological and cytochemical (RNA) studies on rubral neurons after unilateral rubrospinal tractotomy: the impact of GM1 ganglioside administration.

The rubrospinal tract (RST) was cut unilaterally at C2-3 segment in 21 rats that were killed 3, 7, 10, 14, 28, 60, and 90 days later. Additionally, 14 rats, killed 14 or 28 days after lesioning, were treated postoperatively by daily intraperitoneal injections of GM1 ganglioside. Six unoperated, untreated rats served as controls. In untreated animals, axotomized neurons of the magnocellular division of the red nucleus (RN) exhibited cytoplasmic, nuclear, and nucleolar atrophy 7-10 days postoperatively. Atrophy progressed through the 90th postoperative day. Regression analyses disclosed a bimodal pattern to cytoplasmic and nucleolar atrophy, with an initial rapid phase changing to a slower but progressive mode from 14 days postoperatively. Nuclear atrophy proceeded in a unimodal manner. GM1 treatment did not affect these atrophic processes. Neuronal loss did not occur in the axotomized RN through the 60th postoperative day. Axotomized neurons of untreated rats showed significant and progressive reductions in mean somal (cytoplasmic) and nucleolar RNA from, respectively, the 7th and 14th postoperative day. GM1 partly prevented these RNA losses. Both in treated and untreated rats, spinal cord lesions contained many axonal sprouts 2 to 4 weeks after surgery, but newly generated axons did not traverse the rostro-caudal extent of any lesion.

Animals↗
PubMed1989

Kinetics of ethanolic fermentation of D-xylose by Klebsiella pneumoniae and its mutants.

The microbial production of ethanol from D-xylose by a new soil isolate of Klebsiella pneumoniae and the mutants K. pneumoniae MB-16 and MB-16-1048 was studied. Kinetic and physiological properties of the mutants were compared with those of the original isolate. The volumetric rates of ethanol formation by mutants MB-16-1048 and MB-16 and the original isolate were 1.58, 0.50, and 0.06 g liter-1 h-1, respectively. The cultivation times of mutants MB-16-1048 and MB-16 were 20 and 18 h, respectively, and that of the original isolate was 118 h. Both the mutants exhibited metabolic similarities with the original isolate. Ethanol was the major end product of fermentation in all three strains. Acetic acid and carbon dioxide were the other two important by-products of fermentation. Pyruvic acid was accumulated in significant proportions as an intermediate. The proportion of pyruvate in the original isolate was 54% of the total D-xylose utilized, whereas for MB-16 and MB-16-1048 the values were about 42 and 22%, respectively. The lower fractions of pyruvate in mutants MB-16 and MB-16-1048 showed up as a 41 and 82% improvement, respectively, over the original isolate in terms of the ethanol yield.

Acetates↗
PubMed1987

GAL1-GAL10 divergent promoter region of Saccharomyces cerevisiae contains negative control elements in addition to functionally separate and possibly overlapping upstream activating sequences.

The upstream activating sequence (UASG) of the adjacent and divergently transcribed GAL1 and GAL10 promoters of Saccharomyces cerevisiae regulates the induction of the corresponding genes in response to the presence of galactose. We constructed chimeric yeast promoters in which a different UAS, UASC from the iso-1-cytochrome c (CYC1) gene of S. cerevisiae, was fused at different locations upstream of GAL1 (UASC-GAL1 promoters) or GAL10 (UASC-GAL10 promoters) and used to monitor the activity of UASG in cells grown in the presence or absence of galactose. Though the CYC1 promoter is fully induced in yeast grown in glycerol medium, UASC-GAL chimeric promoters containing UASG were repressed as much as 400-fold (UASC-GAL1) or 1350-fold (UASC-GAL10) in this growth medium. Several distinct portions of the GAL1-GAL10 divergent promoter region blocked the UASC-induced expression of the GAL1 and GAL10 promoters, whereas others did not, suggesting that several distinct negative control elements are present that may repress transcription of GAL1 and GAL10 in the absence of galactose. The approximate locations of these negative control elements were delimited to sites adjacent to or possibly overlapping the sites at which the positive control protein GAL4 binds in UASG. Deletion derivatives of GAL4 that fail to induce transcription from the wild-type GAL promoters but retain the DNA binding domain significantly derepressed the expression of the UASC-GAL chimeric promoters. These results, combined with those of earlier studies, suggest the possibility that GAL4 normally induces transcription of GAL1 and GAL10 by blocking the activity of these negative control elements, in addition to stimulating transcription by a mechanism of positive control.

Chromosome Mapping↗
PubMed1987

Involvement of heat shock proteins in bacteriophage Mu development.

Growth of bacteriophage Mu was severely inhibited at elevated temperature in mutants defective in the heat shock genes dnaK, groEL, and groES and in the rpoH (htpR) regulatory mutant, but not in mutants defective in the heat shock genes dnaJ or grpE; growth of a mutant of Mu deficient in functions encoded in the accessory region of the Mu genome was inhibited in the latter two host mutants. Phage production in the dnaJ mutant was restored by growth in low-salt medium. The stage in Mu development primarily affected in all except the groE mutants was phage late transcription. In contrast, the groE mutants did not support growth of Mu at any temperature; neither Mu DNA replication nor transcription was inhibited in these strains, suggesting that groE is required for phage morphogenesis as observed with several other coliphages.

Bacteriophage mu↗
PubMed1986

Differential responses of carcinogen-induced fibrosarcoma of mice to altered regimes of cold exposure.

The effect of chronic and intermittent cold exposure was studied in benzo(a)pyrene-induced fibrosarcoma of mice. Chronic exposure to 5 degrees C caused decrease in incidence, increase in latent period, and inhibition of tumor growth. Intermittent exposures to +5 degrees C and -10 degrees C induced significant enhancement of tumor growth which increased with the lowering of temperature. Concomitant with the tumor growth alterations, stress reactions assessed by plasma corticosterone levels, differed in these two regimes. The elevation of plasma corticosterone levels correlates with the tumor growth enhancement which is probably mediated by corticosterone-induced immuno-suppression. Inhibition of tumors appears to be a result of adaptation to chronic stress, or metabolic alterations in cold. Physiological alterations of the host, depending upon the nature and duration and severity of the "stress" exposure, determines in our opinion probably the course of neoplastic development.

Animals↗
PubMed1985

Mapping of the c-myc, pvt-1 and immunoglobulin kappa genes in relation to the mouse plasmacytoma-associated variant (6;15) translocation breakpoint.

A variant mouse plasmacytoma (MPC)-associated translocation chromosome has arisen by pericentric inversion and exchange of the distal segments of a Robertsonian 6;15 fusion chromosome in the CAK TEPC 1198 mouse plasmacytoma, as described earlier. In situ hybridization was performed on the normal and the inverted Rb chromosomes, using myc and kappa probes. On the normal Rb chromosome, myc was in the 15 D2/3 region, whereas kappa hybridized in the 6 C2 area, as expected. On the inverted Rb chromosome, myc remains on the centrometric side of the translocation breakpoint on the chromosome 15-derived portion, whereas kappa has moved to the chromosome 6-derived segment that joined the same breakpoint on the telomeric side. Taken together with our recent demonstration that the murine c-myc locus is oriented 'head up' on chromosome 15, and with the results of Cory and co-workers concerning the relationship between the kappa gene and the associated pvt-1 region in the CAK TEPC 1198 tumor, the following conclusions can be drawn: (i) in the variant translocation of the CAK TEPC 1198 MPC, the breakage occurs 3' of the c-myc gene, as in the human Burkitt lymphoma-associated variant translocations; (ii) the pvt-1 gene on chromosome 15 is distal to the myc gene; (iii) the kappa light chain locus is oriented 'head up' on mouse chromosome 6 and faces pvt-1 and, beyond it, c-myc, in a head-to-tail configuration.

Animals↗
PubMed1985

A new approach to gene mapping by in situ hybridization on isolated chromosomes.

A new technique was developed for in situ hybridization on isolated murine chromosomes. The safety and relative rapidity of the method is due to the ready availability of large numbers of isolated "target" chromosomes with well preserved morphology. Its applicability was demonstrated by mapping c-myc to band 15D of Robertsonian (6;15) fusion chromosomes. This localization coincides with the cytogenetic mapping of the translocation breakpoints in mouse plasmacytomas that carry the typical rcpt (12;15) translocation.

Animals↗