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Biomedical subjects

S Vidyasagar

Publications and source records attributed to S Vidyasagar.

6 recordsLinked to original sources
PubMed2002

Effects of butyrate on active sodium and chloride transport in rat and rabbit distal colon.

Short chain fatty acids, particularly butyrate, stimulate electroneutral NaCl absorption from the colon. Their effect in colonic epithelia lacking basal electroneutral NaCl absorption is unknown. Butyrate is also reported to inhibit active Cl- secretion in the colon. The present studies were undertaken to investigate the inter-relationships between the effects of butyrate on active Na+ and Cl- transport in the colon. Studies were carried out in rabbit distal colon (known to have predominant electrogenic Na+ absorption), rat distal colon (characterised by electroneutral Na+ absorption), and hyperaldosteronaemic rat distal colon (characterised by electrogenic Na+ absorption). The effect of cholera toxin (CT) was also noted. Potential difference, short-circuit current (I(SC)) and fluxes of Na+ and Cl- were measured in stripped mucosa under voltage-clamp conditions. Butyrate stimulated electroneutral Na+ and Cl- absorption in distal colon of normal and salt-depleted rats, and stimulated Na+ absorption in rabbit distal colon. Amiloride (10(-4) M) or CT did not inhibit this process. In rabbit distal colon, stimulation of Na+ absorption by butyrate was not dependent on the presence of Cl- in the medium. Butyrate significantly decreased conductance, decreased flux of sodium from serosa to mucosa (particularly in rabbit distal colon), and decreased I(SC). Net Cl- secretion, induced by CT, was completely inhibited by butyrate. Stimulation of Na+ absorption was independent of exposure to CT. Bumetanide reversed net Cl- secretion to net absorption, but did not alter Na+ or Cl- fluxes in tissues exposed to butyrate. Thus butyrate stimulates active Na+ absorption in colonic epithelia, with or without expression of basal Na+-H+ exchange. Independently, butyrate inhibits active Cl- secretion induced by cAMP in these epithelia.

Absorption↗
PubMed2001

Nitric oxide protects the intestine from the damage induced by laparotomy and gut manipulation.

BACKGROUND: The intestine is highly susceptible to free radical-induced damage, and our earlier work has shown that surgical stress induces the generation of oxygen free radicals in enterocytes, resulting in intestinal damage along with ultrastructural changes. Since nitric oxide (NO) is an important mediator of gastrointestinal function, this study looked at the effect of NO on surgical stress-induced intestinal alterations. MATERIALS AND METHODS: Control rats and rats pretreated with the NO donor l-arginine were subjected to surgical stress by opening the abdominal wall and handling the intestine as done during laparotomy. Enterocytes were isolated and homogenate prepared, and the protection offered by l-arginine against damage due to surgical stress was determined and compared with normal controls. Protection to structural as well as functional aspects of the intestine was also examined. RESULTS: Intestinal manipulation affected intestinal structure as assessed by electron microscopy. Functional impairment of the enterocyte was also evident, with increased xanthine oxidase activity resulting in production of superoxide anion. This impairment is more dramatic in the crypt cells. Increased protease activity was also seen following laparotomy and handling. Pretreatment with the NO synthase substrate l-arginine prevented these damaging effects. Arginine protection was abolished in the presence of the NO synthase inhibitor NG-nitro-l-arginine methyl ester, indicating the role of NO. CONCLUSION: Stress in the small intestine due to any surgery can affect enterocyte structure and function. These damaging effects can be prevented by NO, an important modulator of cellular function.

Animals↗
PubMed1999

Vincristine (Vinca-alkaloid) as a sclerosing agent for malignant pleural effusions.

Vincristine, extracted from Vinca rosea Linn., is an effective antineoplastic chemotherapeutic drug used in oncology practice. This drug has never been used as a sclerosing agent for the treatment of malignant pleural effusion for reasons unknown. A study was conducted to examine the use of Vinca-Alkaloid as a sclerosing agent (pleurodesis) for the palliative treatment of malignant pleural effusions. The study included 15 patients, all diagnosed to have cytology-proven malignant pleural effusions. Intercostal tube drainage followed by chemical sclerotherapy with 2 mg vincristine was performed on all patients and a high success rate was noted. Twelve procedures out of 15 (12/15) achieved complete resolution of pleural fluid with a success rate of 80%. In two procedures the pleural effusion was reduced and then recurred but did not require re-aspiration. One procedure failed and repeated pleural aspiration was required. In this study, with adequate pleural drainage and the proper technique, vincristine was found to be an effective sclerosing agent for malignant pleural effusion. Further randomized trials are necessary in order to establish the role of this drug.

Adult↗
PubMed1989

Pseudohypertension with calcific aortic stenosis and angina pectoris.

A case of pseudohypertension as demonstrated by a very high systolic blood pressure (more than 280 mm of Hg) by sphygmomanometry and low blood pressure (148/30 mm of Hg) as evidenced by intra-arterial recording who also had severe calcific aortic stenosis, calcified right brachial artery and angina pectoris is described. This case is reported because of the unusual combination of lesions and the therapeutic challenge it poses.

Aged↗
PubMed1988

Infancy and early childhood follow-up of neonates with periventricular or intraventricular hemorrhage or isolated ventricular dilation: a case controlled study.

Survivors of periventricular or intraventricular hemorrhage and isolated ventricular dilation showed a higher incidence of major developmental problems in the motor areas than matched control subjects in infancy. This effect is still seen, but less evident in early childhood. Problems were mainly related to grades III and IV periventricular or intraventricular hemorrhage and isolated ventricular dilation. The outcome of newborns with grades I and II hemorrhage was benign.

Cerebral Hemorrhage↗