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Biomedical subjects

S Samuels

Publications and source records attributed to S Samuels.

At least 73 records · Page 4Linked to original sources
PubMed1978

The structure of a cytochrome oxidase-lipid model membrane.

The structure of "membranous cytochrome oxidase" has been investigated by X-ray diffraction, optical polarization spectroscopy and EPR spectroscopy. These studies indicate that the cytochrome oxidase molecules are oriented symmetrically in the membrane profile with a significant portion of their mass occurring within the extravesicular surface of the membrane; the oxidase molecultes span the membrane profile; the distribution of the oxidase molecules over the plane of these membranes is non-crystalline; the oxidase molecules contain bundles of alpha-helical polypeptide chain segments where the average orientation of the helices is normal to the membrane plane; and the average heme orientation within the oxidase molecules is such that the normal to the heme plane lies in the plane of the membrane.

Animals↗
PubMed1978

Effect of gamma-glutamyl cycle inhibitors on brain amino acid transport and utilization.

Two inhibitors of the gamma-glutamyl cycle, methionine sulfoximine (MSO) and 2-imidazolidone-4-carboxylic acid (ICA) were administered to C57LB/6J mice. Both agents resulted in a reduced rate of transport of tyrosine from blood to brain and a decreased rate of incorporation of tyrosine from plasma into brain protein. MSO administration also diminished to concentrations of brain tyrosine, dopamine, and norepinephrine. MSO decreased the transport rate of valine by brain as well as the rate of its incorporation into protein when expressed in relation to the plasma specific activity. The results demonstrate a significant role for the gamma-glutamyl cycle in the transport of large neutral amino acids from blood to brain.

Amino Acids↗
PubMed1978

Prediction of late survival in patients with mitral valve disease from clinical, hemodynamic, and quantitative angiographic variables.

Late follow-up (average = 7.2 years) has been obtained in 249 patients with mitral valve disease who had quantitative angiographic assessment of left ventricular function at thetime of initial catheterization in the 1960s. Surgically treated patients with mitral valve disease had significantly improved survival as compared to medically treated patients with mitral disease. The subgroup with mixed mitral stenosis and regurgitation and the subgroup with moderate impairment of ejection fraction account for this improved survival in surgically treated patients, which occurred despite greater functional and hemodynamic impairment in the surgical cohorts. Using univariate life table survival analysis, ten variables were found to be predictive of survival in the medical cohort, and three in the surgical cohort. With multivariate Cox's regression analysis, end-diastolic volume and arteriovenous oxygen difference were significantly predictive of survival in the medical cohort; age was predictive of survival in the surgical cohort.

Hemodynamics↗
PubMed1976

Amino acid transport inhibition: brain and behavioral correlates.

In vivo inhibition of uptake 14C-L-valine by brain following subcutaneous administration of either of two gamma-glutamyl cycle enzyme inhibitors, 2-imidazolidone-4-carboxylic acid (ICA), or, L-methionine-S-sulfoximine (MSO) is documented in C57BL/6J mice. Dose related decrease in exploratory activity, impairment of memory for foot shock, and reduced operant responding for food reinforcement parallels the time course for interference with uptake of a large neutral amino acid by these two compounds previously shown to inhibit different enzymes in the gamma-glutamyl cycle subserving active amino acid transport.

Amino Acids↗
PubMed1976

Rapid, colorimetric test for the determination of hippurate hydrolysis by group B Streptococcus.

A colorimetric test for the determination of hippurate hydrolysis was developed. Brain heart infusion broth made with 1% sodium hippurate served as the test medium. Hydrolysis was determined by the addition of two chemical developers, M (rhodamine B) and A (uranium acetate). A dark pink color indicated hydrolysis; no color change indicated no hydrolysis. The method was efficacious in either rapid or overnight incubation. One hundred twenty-five strains of group B, 44 strains of group A, 15 strains of group C, and 10 strains of group G Streptococcus were tested. By using the Lancefield method as the standard, there was 100% agreement with both the colorimetric and ferric chloride tests for hippurate hydrolysis, and 96% agreement with the CAMP test.

Hippurates↗
PubMed1975

Duodenal perforation: a rare complication of neonatal nasojejunal tube feeding.

Continuous nasojejunal drip is a common method of feeding low-birthweight neonates because it is relatively free of complications and provides nutritional requirements. We recently encountered a case of duodenal perforation caused by a feeding catheter. Recommendations are made that can prevent this complication in the future.

Birth Weight↗