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Biomedical subjects

C Ross

Publications and source records attributed to C Ross.

At least 145 records · Page 8Linked to original sources
PubMed1981

First-year medical students and the aging patient: a curricular model.

First-year medical students at UCLA are introduced to the special health problems of the elderly by a process in which they interview symptomatic volunteers at both extended care and ambulatory care facilities. In. addition, they interview healthy elderly volunteers to gain information on gerontology and lifespan development, with supplementation from selected readings, films, lectures and panels. This curricular model seems effective in reducing prejudice about the aged and in training future physicians to render humane competent care in the field of geriatrics.

Aged↗
PubMed1978

Extent of recovery from neonatal damage to the cortical visual system in cats.

Cats that received either marginal or marginal plus extramarginal lesions as 3-day-old kittens were assessed on a series of tests of visually guided behavior. These cats were not conspicuously different from normal controls in avoiding obstacles or in activity level. Yet these same operated cats were severely impaired in performance on the visual cliff and in visual discrimination learning, even when the lesions were limited to the geniculocortical portion of the visual system. However, maximum losses in pattern and form discrimination learning were observed only in cats with severe retrograde degeneration in both the lateral geniculate nucleus and the complex of the pulvinar and nucleus lateralis posterior. Photically evoked potentials were recorded in the lateral regions of the neocortex more reliably from operated cats that had made fewer errors in discrimination learning than from more severely debilitated cases; this relation was present even among cases with nearly equivalent amounts of retrograde degeneration in the visual thalamus. These findings suggest that in the cat (a) recovery of vision is incomplete after neonatal lesions of the visual cortex and (b) a cortical system lateral to the geniculocortical projections may be involved in pattern vision.

Animals↗
PubMed1975

A survey of hospital services for suicidal persons.

A person who threatens or attempts suicide, arriving for treatment at any 1 of 10 hospitals serving a suburban area in the Bay Area of California, will be met with a variety of responses by different kinds of personnel, depending on the hospital to which he comes. In half of the hospitals, he could be subsequently discharged without psychiatric consultation of any kind. Follow-through on any outpatient referral would usually be left up to him. Although a few hospitals attend to the problem of suicidal persons in many important respects, other hospitals pay little attention to these same aspects. Because of the important role of the hospital in the prevention of suicide, it is recommended that the hospital's function in dealing with suicidal patients be better defined, extended, and made more consistent.

Aftercare↗
PubMed1974

Effects of Cycloheximide upon Formation of Ribonucleic Acid Cytidylic and Uridylic Acids.

Concentrations of cycloheximide as low as 3 mug/ml inhibited incorporation of labeled orotic acid or uridine into RNA cytidylic acid of soybean (Glycine max) hypocotyl sections. Even lower concentrations of this well known protein synthesis inhibitor interfered with conversion of labeled cytidine into RNA uridylic acid. Both cycloheximide and puromycin inhibited absorption of (3)H-phenylalanine and its incorporation into protein, but puromycin did not significantly affect the labeling patterns of RNA cytidylic and uridylic acids when orotic acid-6-(14)C was fed. Results give further support to the hypothesis that cycloheximide inhibits the interconversion of uridine and cytidine nucleotides, presumably by acting as a glutamine antagonist in the glutamine-dependent reaction catalyzed by cytidine triphosphate synthetase.

Journal Article↗
PubMed1973

Adenosine 5'-triphosphate-sulfurylase in corn roots and its partial purification.

ATP-sulfurylase (ATP-sulfate adenyltransferase, EC 2.7.7.4) was found in nonparticulate fractions of both roots and leaves of Zea mays L. seedlings using two detection methods. Addition of exogenous pyrophosphatase was essential for maximum rates of conversion of (35)SO(4) (2-) to labeled adenosine phosphosulfate in unpurified root extracts, but not in unpurified leaf extracts. In the presence of exogenous pyrophosphatase, the enzyme from roots exhibited specific activities as high as those obtained with the leaf enzyme. The root enzyme was purified 33-fold by centrifugation and column chromatography procedures. Its molecular weight obtained by Sephadex gel filtration was about 42,000. Its Km for pyrophosphate was 7 mum, while for adenosine phosphosulfate, the Km was 1.35 mum. None of the enzyme fractions studied converted adenosine phosphosulfate into detectable amounts of 3'-phosphoadenosine-5'-phosphosulfate. ATP-sulfurylase was also found in roots of corn seedlings grown aseptically. The data suggest that at least the first reaction in sulfate reduction might proceed as effectively in roots as in shoots.

Journal Article↗
PubMed1971

Pyrimidine metabolism in cotyledons of germinating alaska peas.

Cotyledons from Pisum sativum L. cv. Alaska seeds were excised 12, 36, 108, 132, and 156 hours after imbibition in aerated distilled water. They were then incubated under aseptic conditions for 6 hours in solutions containing either uridine-2-(14)C or orotic acid-6-(14)C. Uridine was more extensively degraded to (14)CO(2) at all germination stages than was orotate, and these rates remained essentially constant at each stage. Incorporation of each compound into RNA increased about 2-fold from the 12th to the 156th hour, although the total RNA present decreased slightly over this interval. Paper chromatography of soluble labeled metabolites produced from orotate showed that the capacity to metabolize this pyrimidine increased markedly as germination progressed. Radioactivity in uridine-5'-P, uridine diphosphate-hexoses, and uridine diphosphate increased most, while smaller or less consistent increases in uridine, uracil, uridine triphosphate, and an unidentified UDPX compound were also observed. The data suggest that orotate metabolism was initially limited by orotidine-5'-phosphate pyrophosphorylase or by 5-phosphoribosyl-1-pyrophosphate. Incorporation of uridine into RNA appeared to be limited at the earliest germination periods by conversion of uridine-5'-P to uridine diphosphate. Thus, during the 1st week of germination the orotic acid pathway and a salvage pathway converting uridine into RNA become activated.

Journal Article↗
PubMed1971

Development of Pyrimidine-metabolizing Enzymes in Cotyledons of Germinating Peas.

Mechanisms controlling conversion of orotic acid-6-(14)C to uridine-5'-phosphate in cotyledons of germinating Alaska peas (Pisum sativum L.) were investigated. The content of 5-phosphoribosyl-1-pyrophosphate was very low in dry seeds, increased to a maximum after about 12 hours of imbibition, and then rapidly declined. Orotidine-5'-phosphate pyrophosphorylase and orotidine-5'-phosphate decarboxylase activities more than doubled during the first 24 hours of germination and then also decreased. These results do not account for the continuous increases of orotate anabolism in such cotyledons as we observed previously. The initial increases in activities of these two enzymes were unaffected by cycloheximide, while the subsequent decreases were less rapid in the presence of this inhibitor. Activities of cotyledonary cytidine deaminase and uridine hydrolase also increased during imbibition, but the activity of only the latter showed a decrease after imbibition was completed. Cycloheximide inhibited the initial rapid increase in uridine hydrolase activity but had little effect on its subsequent decline. Cycloheximide had only slight inhibitory effects on the development of cytidine deaminase activity during the first 62 hours. The evidence suggests that uridine hydrolase might be synthesized de novo during the first few days of germination, but that the other three enzymes might not be.

Journal Article↗