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Biomedical subjects

S Merchant

Publications and source records attributed to S Merchant.

25 records · Page 2Linked to original sources
PubMed1986

Regulation by copper of the expression of plastocyanin and cytochrome c552 in Chlamydomonas reinhardi.

Plastocyanin and cytochrome c552 are interchangeable electron carriers in the photosynthetic electron transfer chains of some cyanobacteria and green algae (P. M. Wood, Eur. J. Biochem. 87:9-19, 1978; G. Sandmann et al., Arch. Microbiol. 134:23-27, 1983). Chlamydomonas reinhardi cells respond to the availability of copper in the medium and accordingly accumulate either plastocyanin (if copper is available) or cytochrome c552 (if copper is not available). The response occurs in both heterotrophically and phototrophically grown cells. We have studied the molecular level at which this response occurs. No immunoreactive polypeptide is detectable under conditions where the mature protein is not spectroscopically detectable. Both plastocyanin and cytochrome c552 appear to be translated (in vitro) from polyadenylated mRNA as precursors of higher molecular weight. RNA was isolated from cells grown either under conditions favorable for the accumulation of plastocyanin (medium with Cu2+) or for the accumulation of cytochrome c552 (without Cu2+ added to the medium). Translatable mRNA for preapoplastocyanin was detected in both RNA preparations, although mature plastocyanin was detected in C. reinhardi cells only when copper was added to the culture. Translatable mRNA for preapocytochrome, on the other hand, was detected only in cells grown under conditions where cytochrome c552 accumulates (i.e., in the absence of copper). We conclude that copper-mediated regulation of plastocyanin and cytochrome c552 accumulation is effected at different levels, the former at the level of stable protein and the latter at the level of stable mRNA.

Chlamydomonas↗
PubMed1979

A radiocolloid study of the reticulo-endothelial system in tropical diseases.

Radiocolloids were used to study the trapping function of the reticulo-endothelial system in 361 children with infectious or non-infectious tropical diseases. Responses of the system varied not only between different types of diseases but also between individuals suffering from the same type of disease, as illustrated (primarily) by numerous scans of the liver and spleen.

Child↗
PubMed1978

The effect of aerosol ipratropium bromide and salbutamol on exercise tolerance in chronic bronchitis.

In a double-blind placebo controlled trial in 24 patients fulfilling the MRC criteria for chronic bronchitis, ipratropium bromide 40 microgram and salbutamol 200 microgram produced similar and significant (P less than 0.001) increases in forced expiratory volume in one second (FEV1) and forced vital capacity (FVC). A greater increase in FEV1 and FVC was seen when both drugs were used together, but this increase did not differ significantly from that produced by either drug alone. Salbutamol increased 12-minute walking distance significantly (P less than 0.001) by 62 +/- 15 metres, whereas the increase of 43 +/- 15 metres observed after ipratropium was not significant (P less than 0.05). With both drugs in combination 12-minute walking distance increased by 72 +/- 15 metres, but this change was not significantly different from that observed with salbutamol alone. If aerosol bronchodilators in the doses used in this study are to be given with a view to improving exercise tolerance in such patients than salbutamol would appear to be the aerosol of choice.

Aerosols↗
PubMed1977

Frequency of inferior vena caval abnormalcy due to a juxtaposed pathology.

Radionuclide inferior vena cavagrams were done in 135 patients who had hepatomegaly, splenomegaly or a mass in the vicinity of the inferior vena cava (I.V.C.). 2-5mCi 66mTc phytate, 99mTc S colloid, 99mTc O4-, 99mTc-LIDA, 99mTc pyridoxyledene glutamate or 113mIn colloid were injected directly and rapidly into either a malleolar or a femoral vein while the patient lay supine under the 13.5'' detector head of a scinticamera. Rapid sequential scintiphotos were manually taken at approximately 1 sec. interval for 20-30 sec. Thus iliac vein, I.V.C., cardiopulmonary zone in infants, aorta and the arterial phase were visualized. 48% of these subjects had an abnormal I.V.C. and the depictions were interestingly varied, indicating that different patients responded in a different manner even to grossly similar pathologies. It became evident that this soft walled vessel could be compressed by both fluids and neoplastic tissue (Fig. 1, 2); the long I.V.C. channel could also be segmentally pushed away by a mass in its vicinity. (Fig. 2, 3, 4). An abnormal arterial flush usually differentiated between benign (Fig. 2) and malignant (Fig. 3) lesions, even when the mass was extra-hepatic (Fig. 4) and retiroperitoneal (Fig. 5). Such a systematic study of I.V.C. had not been possible earlier since the classical x-ray contrast inferior vena cavagram necessitates venous dissection, passage of a catheter, and the injection of large volume of fluid under an unphysiologically high pressure. The simplified radionuclide technique, however, permitted the study of neonates and critically ill subjects with massive ascites, while retaining a satisfactory reproducability.

Abdominal Muscles↗
PubMed1976

Radiorespirometric study of carbohydrate metabolism in childhood liver disease.

The need for a suitable parameter to evaluate patients with chronic liver disease has been felt for some time, especially in order to judge the response to surgical shunts and the influence of certain drugs and diets on the liver. Since the liver is a major organ for carbohydrate metabolism, it was decided to analyze the in vivo oxidation of such substrates as glucose and galactose labeled with 14C. Moderately advanced "Indian childhood cirrhosis" and idiopathic fatty hepatic infiltration were selected to represent diffuse chronic liver disease. Oral administration of 14C-U-glucose or 14C-1-galactose was followed by analyses of 14CO2 in breath by liquid scintillation counting. Conversion of 14C-glucose to 14CO2 was accelerated by both diseases. On the other hand, oxidation of 14C-galactose was slowed in fatty infiltration and was markedly subnormal in Indian childhood cirrhosis.

Carbon Dioxide↗