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Ramesh Chandra

Publications and source records attributed to Ramesh Chandra.

64 records · Page 4Linked to original sources
PubMed2002

Design and structural analysis of hairpin-TFO for transcriptional activation of genes in S. cerevisiae.

Triplex forming oligonucleotides (TFOs) have the potential to modulate gene expression. While most of the experiments are directed towards triplex mediated inhibition of gene expression the strategy potentially could be used for gene specific activation. In an attempt to design a strategy for gene specific activation in vivo applicable to a large number of genes we have designed a TFO based activator-target system which may be utilized in Saccharomyces cerevisiae or any other system where Gal4 protein is ectopically expressed. The total genome sequence of Saccharomyces cerevisiae and expression profiles were used to select the target genes with upstream poly (pu/py) sequences. We have utilized the paradigm of Gal4 protein and its binding site. We describe here the selection of target genes and design of hairpin-TFO including the targeting sequences containing polypurine stretch found in the upstream promoter regions of weakly expressed genes. We demonstrate, the formation of hairpin-TFO, its binding to Gal4 protein, its ability to form triplex with the target duplex in vitro, the effect of polyethylenimine on complex formation and discuss the implication on in vivo transcription activation.

Base Sequence↗
PubMed2002

Synthesis of N-substituted piperazinyl carbamoyl and acetyl derivatives of tetrahydropapaverine: potent antispasmodic agents.

The synthesis and structure-activity-relationship (SAR) for a series of N-substituted piperazinyl carbamoyl 7-15 and piperazinyl acetyl 18-26 derivatives of tetrahydropapaverine have been carried out. The general synthetic methods of carbamoyl tetrahydropapaverine analogues involve N-substituted piperazines and carbamoyl imidazole tetrahydropapaverine as starting materials. Another route for synthesizing these compounds, involving the formation of carbamoyl imidazole piperazine has also been explored. Acylation of tetrahydropapaverine followed by substitution with various piperazinyl moities afforded the acetyl tetrahydropapaverine derivatives. Variously substituted piperazines have been used to monitor the effect of electron releasing and electron withdrawing substituents upon the antispasmodic activity of the molecules. Effect of varying electron densities on the antispasmodic activity, by altering the position of these groups on the benzene ring has also been monitored. Pharmacological methods involve the in vitro antispasmodic activity studies on a freshly removed guinea pig ileum using a force displacement transducer amplifier connected to a physiograph. Among the analogues synthesized in the present study, a promising compound 7, a potent muscle relaxant as compared to papaverine has been obtained.

Animals↗
PubMed2002

Psychogenic cough: a profile of 32 cases.

OBJECTIVE: Psychogenic or nervous cough has generally been viewed as a clinical oddity and largely ignored. Though it is not rare, its clinical profile is not yet well known. METHOD: In the present study, a series of 32 cases of psychogenic cough is reported. RESULTS: Of 32 cases, there were 19 females (59.4 percent) and 13 males (40.6 percent). A majority of patients had cough for more than one month. School phobia (in children) and fear of rejection and need for attention were the most common precipitating or perpetuating factors. Twenty patients (62.5 percent) had a psychiatric disorder, the most common being conversion disorder (21.9 percent) followed by mixed anxiety and depressive disorder (12.5 percent). Drug therapy and/or psychotherapy were used as treatment with 12 cases (37.5 percent) showing remission, 16 cases (50.0 percent) having improvement, and 4 cases (12.5 percent) continuing with the complaint. CONCLUSION: Further studies are warranted to study the treatment and outcome of this important psychiatric disorder.

Adult↗
PubMed2002

Profile of asymptomatic chronic HBV infection in India.

BACKGROUND & OBJECTIVES: In India, horizontal transmission in early childhood has been shown to be a significant mode of transmission of hepatitis B virus (HBV). This prospective, cross-sectional study was undertaken to study the biochemical, serological and histological profile of incidentally detected asymptomatic HBsAg positive subjects (IDAHS) picked up at a tertiary care referral centre. METHODS: In 157 (M:F::123:34) HBsAg positive subjects, clinical, biochemical, virological and histological assessment was done. The histological activity index (HAI) of > 3 was considered as chronic hepatitis. Serum was tested for HBsAg, HBeAg, HBeAb, HBV DNA and alanine transaminase (ALT). RESULTS: Seventy (45%) subjects were HBeAg and 83 (53%) anti-HBe positive. While 71 per cent of the subjects with elevated ALT had an HAI > 3, only 36 per cent with normal ALT showed significant histological changes (P < 0.001). Significant histopathological lesions in the liver biopsy were seen in 92 (59%) subjects, with moderate to severe lesions in 14. IDAHS who were HBeAg +ve were more likely to have significant histological lesion than those who were anti-HBe +ve (P < 0.01). In the anti-HBe +ve group, 35 of 57 (61%) subjects for whom HBV-DNA was available, were HBV-DNA positive. Anti-HBe+ve, HBV-DNA+ ve IDAHS with elevated ALT were more likely to have chronic hepatitis vis-a-vis those subjects in this group who had a normal ALT (P < 0.001). INTERPRETATION & CONCLUSION: ALT is a reliable discriminant of significant histological lesion in IDAHS. The relatively young mean age of Anti-HBe +ve IDAHS suggests an early age of infection and hence, early seroconversion or mutant virus infection in this cohort. A significant proportion of these IDAHS have HBV-DNA positivity and HAI > 3. Our results clearly demonstrate ongoing liver disease in asymptomatic, so-called "HBV carriers". We propose that the term hepatitis B 'carrier' should be abandoned and replaced by 'chronic HBV infection'.

Adolescent↗
PubMed2002

Larvicidal activity of latex and stem bark of Euphorbia tirucalli plant on the mosquito Culex quinquefasciatus.

The methanolic, chloroform and ether extracts of Euphorbia tirucalli latex and stem bark were evaluated for larvicidal activity against laboratory-reared larvae of Culex quinquefasciatus (Diptera: Culicidae), vector of the brancroftian filariasis and worst urban nuisance mosquito. The latex extracts contain more potent larvicidal components (177.14 mg/L-326.37 mg/L) than the stem bark extracts (237.663 mg/L-513.39 mg/L). The order of toxicity (LC50) for the latex extracts was Methanol extract (177.14 mg/L) > Chloroform (200.76 mg/L) > Ether (326.37 mg/L) while the rank of order of toxicity (LC50) of stem bark extracts was Ether (237.66 mg/L) > Chloroform (343.515 mg/L) > Methanol (513.387 mg/L), Higher doses (LC90 24 h of mosquito larvae) of each extract did not cause any mortality among fishes after 24 h. The study gave a weight into the possibility of formulating suitable preparation from the latex and stem bark extracts of the plant for use in mosquito control programme.

Animals↗
PubMedDate not supplied

Modulatory influence of tin-protoporphyrin on gossypol-induced alterations of heme oxygenase activity in male Wistar rats.

Gossypol--a male contraceptive is toxic and causes anorexia, reduction in body weight, hypokalemia etc. It prevents liberation of oxygen from oxyhemoglobin and has hemolytic effect on erythrocytes and leads to microcytic hypochromic anemia. SnPP has been shown to either competitively suppress or to significantly ameliorate a variety of naturally occuring or experimentally induced forms of jaundice in animals and man by inhibiting heme degradation. In this paper novel tissue-dependent response to differential dosing regimen of gossypol and gossypol in association with Sn-protoporphyrin (SnPP) is described. Gossypol was found to be a stimulator of heme oxygenase activity in the liver and kidney to varying degrees. This tissue response contrasted with that of the spleen, where gossypol decreased the activity of the enzyme. The increase in enzymatic activity was accompanied by a decline in the total microsomal protein content on gossypol administration. The gossypol mediated an increase of heme oxygenase activity, elevated bilirubin levels leading to hyperbilirubinemia. The stimulatory effect of gossypol was counteracted to a considerable extent when SnPP was simultaneously administered. Hence, we envision the importance of combined rather than single exposures in defining the realms of toxicology of these and other related drugs. We further envisage the existence of important gossypol-heme interactions in the regulation of heme metabolism.

Animals↗
PubMedDate not supplied

Stimulation of lipid peroxidation and impairment of glutathione-dependent defense system in Wistar rats treated with cryptopine, a rare non-narcotic opium alkaloid.

The present study was designed to evaluate the effect of repeated oral administration of cryptopine at differential dosing regimens (50, 100, 150, 200 mg/kg bwt) in vivo on lipid peroxide measures, glutathione levels (GSH) and activity of glutathione S-transferase (GST) and glutathione reductase (GR) in the liver, spleen, kidney and lung of Male Wistar rats after a 5 day treatment period. In all the tissues examined, we observed an increase in lipid peroxidation and a decline in glutathione content and activity of glutathione S-transferase and glutathione reductase in a dose-dependent manner. The decrease in GSH content did not definitively correlate with a concomitant increase of lipid peroxidation in all the tissues. Our results ensemble that the enhancement of lipid peroxidation in the tissues investigated is a consequence of depletion of glutathione to certain critical levels and impairment of the glutathione-dependent enzyme systems viz. GST and GR. Our study potentiates that decreased levels of GSH may lead to lipid peroxidation, one of the key events in cellular damage. The inhibition of GST also suggests that the detoxification of the alkaloid could be suppressed following acute exposures. Conclusively, it appears that cryptopine in vivo disturbs the cellular defense system, so that it tips in the direction of autoxidative lipid peroxidation, producing cytotoxicity.

Alkaloids↗
PubMedDate not supplied

Papaverine, an opium alkaloid influences hepatic and pulmonary glutathione S-transferase activity and glutathione content in rats.

The present study evaluates the effect of oral administration of papaverine at differential dosing regimens (100 mg/kg bw and 200 mg/kg bw) on the hepatic and pulmonary glutathione S-transferase (GST) activity and glutathione content (GSH) in male Wistar rats. Papaverine treatment caused a pronounced increase in GST activity and GSH content at the higher dosing level in the rat liver and lung. We conclude that papaverine, can possibly act as a chemopreventive agent against chemical carcinogenesis.

Animals↗
PubMedDate not supplied

Modulatory influence of noscapine on the ethanol-altered hepatic biotransformation system enzymes, glutathione content and lipid peroxidation in vivo in rats.

The modulatory potential of noscapine, an opium alkaloid was assessed on the ethanol-induced changes in hepatic drug metabolizing enzyme systems, glutathione content and microsomal lipid peroxidation. Noscapine was administered orally to male Wistar rats at a dose level of 200 mg/kg bw alone as well as in combination with 50% ethanol (v/v) for 5 days. Noscapine administration was associated with a approximately 91% decrease in hepatic microsomal cytochrome P-450 content. A decline of approximately 36% was observed in the NADPH-cytochrome c reductase activity on noscapine administration. The lowering of cytochrome P-450 levels on noscapine administration was accompanied by a concomitant increase in heme oxygenase activity as well as serum bilirubin levels. Our results indicate that the combination dosage of noscapine and ethanol antagonised the ethanol-induced elevation of cytochrome P-450 levels. Noscapine fed rats had decreased glutathione (GSH) content and enhanced lipid peroxidation compared to control rats as indexed by MDA method. Further, noscapine and ethanol coexposure produced a more pronounced elevation in lipid peroxidation and the glutathione levels also decreased significantly. We speculate on the basis of our results that the significant enhancement of lipid peroxidation on combination dosage of noscapine and ethanol is a consequence of depletion of glutathione to certain critical levels. The inhibition of glutathione-S-transferase (GST) as well as lowering of cytochrome P-450 suggests that the biotransformation of noscapine and ethanol is significantly altered following acute coexposures.

Animals↗