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Biomedical subjects

S Black

Publications and source records attributed to S Black.

At least 145 records · Page 8Linked to original sources
PubMed1983

A novel thiol-dependent arsenite-sensitive valyl-tRNA synthetase activity from yeast.

Arsenite strongly inhibits the activation by thiols of a fraction of the valyl-tRNA synthetase in yeast extracts that precipitates in low concentrations of ammonium sulfate. Once activated, however, the enzyme is insensitive to arsenite. It is suggested that arsenite blocks the function of an enzyme-bound hydrogen-transferring agent that mediates reduction of the enzyme and normally serves as part of an oxido-reduction regulatory mechanism. On gel filtration, much of the arsenite-sensitive activity behaves as a complex of about 500,000 molecular weight, whereas the behavior of the arsenite-insensitive activity is consonant with the molecular weight of 130,000 previously reported for yeast valyl-tRNA synthetase.

Amino Acyl-tRNA Synthetases↗
PubMed1983

Linoleate and possibly linolenate deficiency in a patient on long-term intravenous nutrition at home.

A 39-year-old female with scleroderma was maintained on total parenteral nutrition (TPN) at home for four years. She received 2 units of a 10% fat emulsion per week in which 55% of the fatty acids were from linoleate and 7% from linolenate. She was initially placed on TPN because she had difficulty in swallowing due to scleroderma. At the end of four years she had a triene:tetraene ratio of greater than 1. There was evidence of alterations in membrane function due to essential fatty acid deficiency including CNS involvement (blindness, impaired hearing and disorientation) as well as respiratory insufficiency. The diagnosis of membrane involvement was made from gas chromatography (gc) and gc-mass spectroscopy (ms) analysis of red cell membranes which were deficient in linoleate. The patient's immediate cause of death was from respiratory insufficiency.

Adult↗
PubMed1983

Response of the seminiferous epithelium of the mouse exposed to low dose high energy (HZE) and electromagnetic radiation.

This study was undertaken to observe the response of a rapidly dividing cell population (spermatogonial) to Helium and Argon ions as compared to x-rays. Low doses (below 100 rads) were used to more nearly simulate radiation encountered during space missions. The methods used proved compatible for both light and electron microscope studies. The average relative biological effectiveness (RBE) for Helium ions is 1, while Argon is twice as effective in killing spermatogonial cells. Part of this mixed population of cells exhibits a higher sensitivity to radiation below 15 rads. Quantitation of the radiation effects by counting the necrotic cells is not feasible because of their rapid removal, therefore all measurements were done using the surviving fraction (S/So) of spermatogonial cells.

Animals↗
PubMed1982

The assessment of binge eating severity among obese persons.

The purpose of this study was to conduct an assessment of binge eating severity among obese persons. Two questionnaires were developed. A 16-item Binge Eating Scale was constructed describing both behavioral manifestations (e.g., eating large amounts of food) and feeling/cognitions surrounding a binge episode (e.g., guilt, fear of being unable to stop eating). An 11-item Cognitive Factors Scale was developed measure two cognitive phenomena thought to be related to binge eating: the tendency to set unrealistic standards for a diet (e.g., eliminating "favorite foods") and low efficacy expectations for sustaining a diet. The results showed that the Binge Eating Scale successfully discriminated among persons judged by trained interviewers to have either no, moderate or severe binge eating problems. Significant correlation between the scales were obtained such that severe bingers tended to set up diets which were unrealistically strict while reporting low efficacy expectations to sustain a diet. The discussion highlighted the differences among obese persons on binge eating severity and emphasized the role of cognitions in the relapse of self control of eating.

Adult↗
PubMed1982

Management of Candida peritonitis with intravenous amphotericin: Peritoneal fluid antibiotic levels.

The child presented in this report received intravenous amphotericin B 0.5 mg/kg every 36 hours, for dialysis-associated Candida peritonitis. Just prior to her third dose of amphotericin B, the peritoneal fluid concentration of this drug was 0.1 mcg/ml, and the simultaneous serum level was 0.2 mcg/ml. An hour following the third amphotericin B dose, the peritoneal fluid and serum concentrations were 0.2 and 0.4 mcg/ml respectively. The minimal inhibitory concentration (MIC) of amphotericin B for the C. albicans isolated from this patient was 0.05 mcg/ml, and the minimal lethal concentration (MLC) was 0.1 mcg/ml. Treatment included concurrent 5-fluorocytosine, and catheter removal. This is the first time that measurements of concentrations of amphotericin B in the peritoneal fluid have been reported in a child with peritonitis.

Amphotericin B↗
PubMed1981

A reinvestigation of the role of the grey crescent in axis formation in xenopus laevis.

Gravitationally induced displacements of the contents of the frog egg can predictably determine the orientation of the subsequent dorsal-ventral axis of the embryo, regardless of the original position of sperm entry or of the grey crescent. In certain conditions, these displacements in the egg can also lead to the formation of a second axis, that is, to twinning. The previously reported ability of grafts of grey crescent cortex to induce secondary axes in recipient eggs is interpreted here as an unrecognized twinning effect of gravity. Our results lead to question the classic interpretation of the grey crescent as a dorsal determinant in amphibian development.

Animals↗
PubMed1980

Oxygen consumption for lower extremity exercises in normal subjects and burned patients.

The purpose of this study was to compare the oxygen requirements for normal subjects and burned patients during rest and while performing two separate exercises of the quadriceps femoris muscles. The oxygen consumption of 10 normal subjects and 10 burned patients while at rest and while performing each exercise was measured. The resting and exercising oxygen-consumption levels for burned patients were significantly greater (p < .01) than for normal subjects. However, the mean difference in increased oxygen consumption during two exercises for normal subjects and for burned patients was not significant (p > .05). The elevated resting and exercising oxygen-consumption levels in burned patients were considered to be related to the hypermetabolic response characteristic of thermally injured patients.

Adolescent↗
PubMed1980

Retinal changes in rats flown on Cosmos 936: A cosmic ray experiment.

Ten rats, five centrifuged during flight to simulate gravity and five stationary in flight and experiencing hypogravity, orbited the Earth. No differences were noted between flight-stationary and flight-centrifuged animals, but changes were seen between these two groups and ground controls. Morphological alterations were observed comparable to those in the experiment flown on Cosmos 782 and to the retinal cells exposed to high-energy particles at Berkeley. Affected cells in the outer nuclear layer showed swelling, clearing of cytoplasm, and disruption of the membranes. Tissue channels were again found, similar to those seen on 782. After space flight, preliminary data indicated an increase in cell size in montages of the nuclear layer of both groups of flight animals. This experiment shows that weightlessness and environmental conditions other than cosmic radiation do not contribute to the observed damage of retinal cells.

Animals↗
PubMed1979

Hydrogen bonding in solution between the uracil ring and the peptide backbone demonstrated by nuclear magnetic resonance spectroscopy.

Proton and 13C nuclear magnetic resonance measurements indicate that uracil derivatives dissolved in chloroform bind to glycine and phenylalanine tripeptide derivatives through pairs of hydrogen bonds. The N(3)--H and C(4)=0 groups of the uracil ring appear to interact with the C=0 and N--H groups, respectively, of individual amino acid residues, suggesting a fundamental complementarity between uracil and the peptide backbone. The binding occurs in the same concentration range as the hydrogen bonding between derivatives of adenine and uracil under comparable conditions.

Glycine↗
PubMed1978

Cosmic ray effects on the eyes of rats flown on Cosmos No. 782, experimental K-007.

The eyes from six rats were fixed at the recovery site in Russia after they had circled the earth for 19.5 d in a 62.8 degree orbit. The eyes of six more flight rats were fixed 25 d later. These two preparations and eyes exposed to 1000 rad of neon and argon were compared to obtain data on possible radiation effects on the retina. Most of the flight eye tissue was normal; however, necrotic nuclei were found in the outer nuclear layer and channels were located in the outer segment area. Macrophages were seen between the pigment layer and outer segments. Comparison of the Day zero znd 25-d postflight eyes suggested some possible recovery. Light flashes seen by space travelers and damage from cosmic rays appear to arise from two different sites of interaction. The flashes are created by cosmic ray transversal of the outer segments while pathologic change, when it occurs, is quite possibly from interaction with some part of the nucleus. Nevertheless, direct interaction with other cellular components could also occur. Other factors, such as secondaries from spacecraft shielding, may play an important role.

Animals↗