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Biomedical subjects

S B Roy

Publications and source records attributed to S B Roy.

At least 19 recordsLinked to original sources
PubMed1994

Development of high-molar-mass cellobiase complex by spontaneous protein-protein interaction in the culture filtrate of Termitomyces clypeatus.

The 450 kDa cellobiase from Termitomyces clypeatus which migrates as a single band on IEF, PAGE and SDS-PAGE, was found to possess appreciable sucrase activity. The fungus produced sucrase and cellobiase constitutively in different media but with different activity ratios. The kinetics of secretion of the two enzymes was similar under in vivo and in vitro conditions. HPGPLC analysis of the culture filtrates indicated the presence of both sucrase and cellobiase in the same protein fractions of different molar mass, even in the 30-kDa protein fraction. No free sucrase or cellobiase could be detected in the culture filtrates. It was also observed that fractionation of cellobiase by (NH4)2SO4 precipitation was different with different amounts of associated sucrase activity present in the culture filtrate. The (NH4)2SO4-precipitated cellobiase fraction also contained cellobiases in proteins of widely varied molar mass ranges. However, none of the low-molar mass proteins other than the 450-kDa enzyme could be purified, as all low-molar-mass fractions spontaneously aggregated to the 450-kDa enzyme. Hydrophobic chromatography of the (NH4)2SO4-precipitated fractions followed by HPGPLC of the eluted active fraction yielded both cellobiase-free sucrase and a very low sucrase-containing cellobiase fraction. The cellobiase fraction, homogeneous in PAGE, was also a high-molar-mass protein complex dissociating into a number of protein bands on SDS-PAGE.(ABSTRACT TRUNCATED AT 250 WORDS)

Basidiomycota↗
PubMed1981

Reduced physical work capacity at high altitude--a role for left ventricular dysfunction.

Physical work capacity is reduced in sea level residents--lowlanders (LL) as compared to high altitude residents--highlanders (HL). To determine possible etiologies, cardiac performance was studied in two groups of healthy male volunteers (13 LL and 11 HL) utilizing systolic time intervals during rest, submaximal and maximal exercise. The LL were studied at sea level and subsequently during 10 days of residence at an altitude of 3658 m. The HL were studied at high altitude alone. The LL were restudied 30-45 min after administration of intravenous furosemide at high altitude. Mean maximal oxygen uptake (VO2max) was reduced by 26% in the LL group at high altitude in comparison to sea level values and by 20% in relation to the HL group. Cardiac performance was estimated by the pre-ejection period/left ventricular ejection time ratio. This index was significantly increased in the LL group at high altitude in comparison to sea level values during submaximal and maximal exercise (P less than 0.01). Intravenous furosemide in the LL group increased the heart rate (P less than 0.05) at rest and during exercise but VO2max and cardiac performance were unchanged. It is hypothesized that reduced physical work capacity at high altitude in the LL group may be related to depression of cardiac performance in these subjects. Administration of intravenous furosemide did not influence cardiac performance in the LL group at high altitude.

Adult↗
PubMed1977

Metoprolol--a new cardioselective beta-adrenoceptor blocking agent for treatment of tachyarrhythmias.

The antiarrhythmic effect of the cardioselective beta-adrenoceptor blocking agent metoprolol, given intravenously, was studied in 44 patients with various tachyarrhythmias, including patients with congestive heart failure and signs of digitalis intoxication. All patients with atrial tachycardia (12 cases) reverted to normal sinus rhythm. In 3 out of 18 patients with atrial fibrillation, sinus rhythm was restored, and in the others there was a significant reduction in ventricular rate. In 6 of 10 patients with ventricular ectopic beats, and 1 of 2 patients with ventricular tachycardia, the ectopic rhythm was abolished. The drug was well tolerated, without any significant changes in blood pressure, even by patients with signs of digitalis intoxication and varying degrees of pulmonary or peripheral circulatory congestion. Metoprolol is of clinical value for treatment of tachyarrhythmias, especially those of supraventricular origin.

Adolescent↗
PubMed1975

Relationship of pulmonary artery diastolic and pulmonary artery wedge pressures in mitral stenosis.

Resting and exercise hemodynamic studies were performed in 22 patients with mitral stenosis (14 men and 19 women; average age, 25 years) in normal sinus rhythm with normal pulmonary vascular resistances. A normal pulmonary vascular resistance was assumed when the resting pressure gradient between the pulmonary artery diastolic and mean pulmonary artery wedge pressures was 5 mm. Hg or less. A satisfactory correlation existed between the pulmonary artery wedge and pulmonary artery diastolic pressures at rest (r equals 0.9017) and during exercise (r equals 0.8670). A method of predicting pulmonary artery wedge pressure from pulmonary artery diastolic pressure during exercise was formulated. The correlation between the predicted and measured exercise pulmonary artery wedge pressures was very close (r equals 0.9561). It is suggested that during exercise the pulmonary artery diastolic pressure can be modified as above and substituted for mean pulmonary artery wedge pressure if the resting gradient between pulmonary artery wedge and pulmonary artery diastolic pressure is known.

Adolescent↗
PubMed1975

Effects of high altitude hypoxia on left ventricular systolic time intervals in man.

Effects of high altitude hypoxia on systolic time intervals were examined in 34 healthy men: 20 sea level residents studied at rest and at the end of 3 minutes steady isometric (handgrip) exercise at sea level and then serially for the first 5 days and on the tenth day, at an altitude of 3658 m, and I4 permanent residents at high altitude studied at high altitude. In the sea level residents there was a significant increase in the pre-ejection period (PEP), abbreviation of the left ventricular ejection time (LVET), both corrected for heart rate, and prolongation of the PEP/LVET ratio at high altitude. The maximum changes were seen on days 2 and 3; these parameters tended to approach sea level control values by the tenth day. The systolic time interval values of high altitude residents were similar to the control values of the sea level residents obtained at sea level but significantly different from the changes in the sea level values seen in the first 4 days at high altitude. It thus appears that while the high altitude residents do not show any left ventricular dysfunction as determined by systolic time intervals, healthy sea level residents when exposed to high altitude hypoxia show a significant depression of the left ventricular function for at least the first 4 days. This might be a contributing factor in the genesis of high altitude pulmonary oedema.

Adult↗
PubMed1974

Transthoracic electrical impedance in cases of high-altitude hypoxia.

Changes in transthoracic electrical impedance (T.E.I.) due to high-altitude hypoxia (3,658 m) have been measured in 20 young, healthy Indian soldiers. They were first studied at sea level (198 m) and then rapidly transported by air to 3,658 m, where they were studied daily from day 1 to day 5 and then on days 8 and 10. The mean (+/-S.D.) T.E.I. at sea level (34.6+/-0.6Omega) fell sharply to 29.6+/-0.8Omega, 30.3+/-0.9Omega, and 30.5+/-1.1Omega on days 1, 2, and 3 (P <0.001) and levelled off at 31.5+/-0.7Omega on day 10, which was comparable to the mean value obtained in 13 persons permanently resident at high altitude (32.2+/-0.7Omega). Five sea-level residents who had acute mountain sickness (A.M.S.) or high-altitude pulmonary oedema (H.A.P.O.) had a still lower mean value (22.5+/-1.1Omega). One normal healthy subject who at sea level had a T.E.I. of 34.7Omega developed H.A.P.O. when the T.E.I. fell to 21.1Omega. Ninety minutes after the administration of 80 mg of intravenous frusemide the value increased to 35.5Omega. In another subject with A.M.S. who received 40 mg of frusemide intravenously the T.E.I. rose from 21.9 to 33.2Omega.Since the study was non-invasive the changes in impedance could not be correlated objectively with alterations in either pulmonary blood volume or pulmonary extravascular water space. In the subject, however, with x-ray evidence of H.A.P.O. and a low T.E.I. intravenous frusemide produced a marked rise in T.E.I. together with clearing of the chest x-ray picture within 24 hours, indicating an inverse relationship between impedance and thoracic fluid volume. It is suggested that with further objective verification in man the measurement of T.E.I. may be a potentially promising technique for the early detection of increased pulmonary fluid volume.

Adult↗