PubMed Health⌕ Search

Biomedical subjects

S C Verma

Publications and source records attributed to S C Verma.

At least 19 recordsLinked to original sources
PubMed2007

Structure and function of latency-associated nuclear antigen.

Latency-associated nuclear antigen (LANA) encoded by open reading frame 73 (ORF73) is the major latent protein expressed in all forms of KSHV-associated malignancies. LANA is a large (222-234 kDa) nuclear protein that interacts with various cellular as well as viral proteins. LANA has been classified as an oncogenic protein as it dysregulates various cellular pathways including tumor suppressor pathways associated with pRb and p53 and can transform primary rat embryo fibroblasts in cooperation with the cellular oncogene Hras. It associates with GSK-3beta, an important modulator of Wnt signaling pathway leading to the accumulation of cytoplasmic beta-catenin, which upregulates Tcf/Lef regulated genes after entering into the nucleus. LANA also blocks the expression of RTA, the reactivation transcriptional activator, which is critical for the latency to lytic switch, and thus helps in maintaining viral latency. LANA tethers the viral episomal DNA to the host chromosomes by directly binding to its cognate binding sequence within the TR region of the genome through its C terminus and to the nucleosomes through the N terminus of the molecule. Tethering to the host chromosomes helps in efficient partitioning of the viral episomes in the dividing cells. Disruptions of LANA expression led to reduction in the episomal copies of the viral DNA, supporting its role in persistence of the viral DNA. The functions known so far suggest that LANA is a key player in KSHV-mediated pathogenesis.

Animals↗
PubMed2004

Enrichment and identification of bacteria capable of reducing chemical oxygen demand of anaerobically treated molasses spent wash.

AIMS: The aim of this study was to isolate and identify bacterial strains capable of using recalcitrant compounds of molasses spent wash as sole carbon source from the soils of abandoned sites of distillery effluent discharge and characterize their ability of reducing the chemical oxygen demand (COD) of the spent wash. METHODS AND RESULTS: The isolates were grouped into six haplotypes by amplified ribosomal DNA restriction analysis (ARDRA) and BOX-PCR. The phylogenetic position of the representatives of the six main haplotypes strains was determined by 16S rDNA sequencing. They showed maximum similarity to six genera viz. Pseudomonas, Enterobacter, Stenotrophomonas, Aeromonas, Acinetobacter and Klebsiella. The extent of COD (44%) reduced collectively by the six strains was equal to that reduced individually by Aeromonas, Acinetobacter, Pseudomonas and Enterobacter. With spent wash as sole carbon source, the COD reducing strains grew faster at 37 degrees C than 30 degrees C. CONCLUSIONS: Bacterial strains capable of degrading some of the recalcitrant compounds of anaerobically digested molasses spent wash can be isolated from the soils of abandoned sites of distillery effluent discharge. Biostimulation of these bacteria, which can degrade 44% of the carbon compounds of anaerobically digested molasses spent wash can be achieved by nitrogen fertilization and relatively higher temperature. SIGNIFICANCE AND IMPACT OF THE STUDY: Supplementation of nitrogen source and controlling the temperature can be used in evolving strategies for in situ bioremediation of anaerobically digested spent wash from distilleries.

Bacteria↗
PubMed2004

Molecular diversity of tannic acid degrading bacteria isolated from tannery soil.

AIMS: The aim of this study was to enrich and isolate bacteria from a tannery soil that were capable of utilizing tannic acid and gallic acid as sole source of carbon aerobically, and to characterize their diversity in order to identify efficient strains that can be used for tannin bioremediation. METHODS AND RESULTS: Bacterial strains were isolated after enrichment in minimal medium with tannic acid or gallic acid as sole carbon source. Polymerase chain reaction (PCR) restricted fragment length polymorphism of 16S rDNA [amplified ribosomal DNA restriction analysis (ARDRA)] and BOX-PCR was used to characterize their diversity. Two strains showing relatively high efficiency in degrading tannic acid and gallic acid were identified on the basis of carbon source utilization pattern (BIOLOG) and 16S rDNA sequence. CONCLUSIONS: Bacterial strains capable of degrading tannic acid and gallic acid could be grouped into six and seven clusters on the basis of ARDRA and BOX-PCR, respectively. On the basis of 16S rDNA sequence, the most efficient isolate degrading tannic acid belonged to Pseudomonas citronellolis, whereas the most efficient gallic acid degrader showed maximum phylogenetic relatedness to P. plecoglossicida. SIGNIFICANCE AND IMPACT OF THE STUDY: Aerobic tannic acid degraders such as the two strains isolated in this study can be used for tannin bioremediation, and in the study of genes involved in the production of tannase, an industrially important enzyme.

Benzoates↗
PubMed2001

Evaluation of plant growth promoting and colonization ability of endophytic diazotrophs from deep water rice.

A study of the diversity of endophytic bacteria present in seeds of a deepwater rice variety revealed the presence of seven types of BOX-PCR fingerprints. In order to evaluate the plant growth promoting potential the presence of nitrogenase, indole acetic acid production and mineral phosphate solubilization were estimated in the representative BOX-PCR types. The seven representatives of BOX-PCR types produced indole acetic acid, reduced acetylene and showed specific immunological cross-reaction with anti-dinitrogenase reductase antibody. Only four types showed mineral phosphate solubilizing ability. Comparison of cellulase and pectinase activities showed differences among different BOX-PCR types. PCR fingerprinting data showed that one strain isolated from the surface sterilized seeds as well as the aerial parts of the seedlings of rice variety showed low cellulase and pectinase but relatively high ARA. On the basis of 16S rDNA nucleotide sequence and BIOLOG system of bacterial identification, this strain was identified as Pantoea agglomerans. For studying the endophytic colonization this strain was genetically tagged with the reporter gene, gusA. Histochemical analysis of the seedling grown in hydroponics showed that the tagged strain colonized the root surface, root hairs, root cap, points of lateral root emergence, root cortex and the stelar region. Treatment of the roots with 2,4-D produced short thickened lateral roots which showed better colonization by P. agglomerans.

2,4-Dichlorophenoxyacetic Acid↗
PubMed2000

Management of anterior segment penetrating injuries with traumatic cataract by Pentagon approach in paediatric age group: constraints and outcome.

PURPOSE: To evaluate the efficacy of multiple combined procedure (Pentagon approach) as single-step secondary repair in cases of extensive keratolenticular trauma in paediatric age group. METHODS: Retrospective evaluation of 18 patients of penetrating injuries with sclerokeratolenticular trauma, who underwent multiple procedure as single-step secondary repair by a single team of two surgeons during a 4 year period. Surgical procedure included reconstruction of anterior segment, synechiolysis, excision of membrane, lensectomy, open sky vitrectomy, PC IOL implantation over frill and penetrating keratoplasty. Meticulous antiamblyopia measures were applied in all cases. RESULTS: Extensive vasoproliferative membrane, complicated cataract and anterior vitreous condensation were significant intra-operative hurdles. Moderate uveitis, secondary glaucoma, persistent epithelial defects were problems noted. Eleven (61.22%) patients attained good visual outcome. Regrafting was required in remaining cases due to delayed graft failure. CONCLUSION: Despite being a highly complex technique, Pentagon approach provides effective management profile in terms of graft success and functional outcome, especially in keratolenticular trauma, in children.

Amblyopia↗
PubMed1983

The inhibitory effect of clonidine on the oestrogen-primed rat isolated uterus.

The investigation was undertaken to study the mechanism of the inhibitory effects of clonidine on the oestrogen-primed rat isolated uterus. Clonidine produced dose-dependent relaxations of the rat isolated uterus which were competitively blocked by yohimbine but not by prazosin. Metiamide, a specific H2-histamine receptor antagonist, inhibited clonidine-induced responses only at a high concentration (1.0 X 10(-6)M). Propranolol, a beta-adrenoreceptor antagonist produced competitive antagonism of the clonidine responses. Like clonidine, noradrenaline also produced dose dependent relaxations of the rat isolated uterus. The responses to noradrenaline were not antagonized by either prazosin or yohimbine but were competitively antagonized by propranolol. The responses to clonidine were significantly inhibited by reserpine pretreatment (5 mg/kg; i.p., 24 h before) whilst responses to noradrenaline were significantly increased by this treatment. It is concluded that clonidine inhibits the uterus via an action on alpha 2-adrenoreceptors and possibly also to a lesser extent on H2-histamine receptors, leading ultimately to release of noradrenaline from endogenous stores which causes relaxation by acting on beta-adrenoreceptors.

Animals↗
PubMed1982

Mechanism of action of histamine in the estrogen-primed rat uterus.

Histamine produced a dose-dependent relaxation of uterine strips obtained from the estrogen-primed rat uterus. The responses to histamine were blocked competitively by metiamide (10(-8)-10(-8) M), a specific H2-receptor antagonist. Propranolol, a selective beta-receptor blocker also produced competitive antagonism of the responses to histamine in the same dose range (10(-8)-10(-6) M). The pA2 value obtained for metiamide (8.9) was not significantly different from that obtained for propranolol (8.6). Nialamide (2.2 X 10(-6) M), the monoamine oxidase inhibitor, and cocaine (4.3 X 10(-6) M), the selective noradrenaline uptake blocker, potentiated the responses to histamine. However bretylium (2.4 X 10(-5) M), and adrenergic neuron blocker inhibited the responses to histamine. The combined effect of tyramine and histamine was found to be additive. Our data suggest that the histamine-induced relaxation of rat uterus may be produced through the stimulation of presynaptic H2-receptors which causes the release of noradrenaline. The released noradrenaline acts on the postsynaptic beta-receptors and produces relaxation of the rat uterus.

Animals↗
PubMed1982

Cyclic AMP-dependent and independent positive inotropic effects of phenylephrine.

To summarize, a large number of studies indicate that the effects of phenylephrine on cardiac contractility are mediated through alpha-adrenoceptors, although not exclusively. There are an equally large number of reports indicating some beta-adrenoceptor stimulant effects of phenylephrine. Of the latter, some are based on the finding of antagonism by beta-receptor antagonists and some on the fact that phenylephrine is capable of elevating cyclic AMP levels, which is primarily a beta-, and not alpha-adrenoceptor effect. Although it is now widely accepted that phenylephrine elevates cyclic AMP levels, the contribution and significance of the elevated nucleotide levels to the overall positive inotropy of phenylephrine appears to be small. Alpha-Adrenoceptors may be involved with calcium, although the precise interaction between calcium and the alpha-adrenoceptor is not clear. Finally, the adrenergic effects seem to depend on the experimental and physiological conditions including calcium ion concentration, thyroid state and driving frequency.

Animals↗