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Biomedical subjects

J Roberts

Publications and source records attributed to J Roberts.

At least 613 records · Page 34Linked to original sources
PubMed1977

Red blood cell glycolysis and potassium type in sheep.

Based on the observations made on human and dog red blood cells, it was recently proposed that the response of red cell glycolysis to variations in the levels of specific cations in an evolutionary adaptation in response to a specific cellular environment. We have now examined the effect of K+ and Na+ on the activity of pyruvate kinase (PK) in the red blood cells from 2 genetically different types of sheep high potassium (HK) and low potassium (LK). The results indicate that K+ stimulate glucose consumption and the activity of PK in both types of sheep. It thus appears that red cell PK from LK sheep does not fit into the concept of cellular environment and PK activity.

Adaptation, Physiological↗
PubMed1977

Isolation, crystallization, and properties of indolyl-3-alkane alpha-hydroxylase. A novel tryptophan-metabolizing enzyme.

Indolyl-3-alkane alpha-hydroxylase, a novel tryptophan-metabolizing enzyme, was prepared in crystalline form from soil isolate organism Pseudomonas XA. Emission spectroscopy and atomic absorption analyses of purified enzyme revealed the presence of iron (0.8 mol/mol of protein), and a number of observations supported the presence of heme prosthetic group (1.1 mol/mol of protein). The S20,w value of indolyl-3-alkane alpha-hydroxylase is 10.2 S, and the molecular weight by sedimentation equilibrium ultracentrifugation is 250,000. The E1%280 of the enzyme is 21, and the isoelectric point by isoelectric focusing on ampholine polyacrylamide gel plates is 4.8. The enzyme catalyzes hydroxylation on the side chain of a variety of 3-substituted indole compounds, including certain tryptophan-containing oligopeptides. The reaction product from tryptamine was identified by proton nuclear magnetic resonance and gas chromatography/mass spectroscopy analyses. While the indole ring remained intact, hydroxylation occurred at the side chain carbon adjacent to the ring. Nuclear magnetic resonance studies indicated that hydroxylation always took place at the same position when the substrate was tryptophan methyl ester, tryptophol, indole-3-propionate, or indole-3-butyrate. No other chemical change occurred when these substrates were incubated with the enzyme. The Km value of indolyl-3-alkane alpha-hydroxylase for L-tryptophan is 2.4 X 10(-6) M, at pH 7.2. The enzyme is inhibited by potassium cyanide (0.1 mM) or hydroxylamine (1mM), but not by NaBH4 (25 mM), aminooxyacetic acid (7mM), quinacrine (1 mM), chlortetracycline (1 mM), p-mercuribenzoate (0.1 mM), or ethylenediaminetetraacetate (1 mM). The plasma half-life (t1/2) of indolyl-3-alkane alpha-hydroxylase in tumor-bearing mice is approximately 25 h.

Amino Acids↗
PubMed1977

Biochemical polymorphism and the 2,3-diphosphoglycerate in the sheep red blood cells.

There was no significant difference in the level of 2,3-DPG in the red blood cells of sheep of different haemoglobin types (Hb A and Hb B) or potassium types (HK and LK). However, low glutathione (GSHL) sheep had significantly higher (p less than 0.01) level of 2,3-DPG in their red blood cells than high glutathione (GSHH) sheep. There was also significant effect of interactions between glutathione, haemoglobin and potassium types (p less than 0.05) and glutathione and haemoglobin types (p less than 0.01) on red cell 2,3-DPG levels.

Animals↗
PubMed1977

Predicting child abuse: signs of bonding failure in the maternity hospital.

Fifty children referred to the Park Hospital because of actual or threatened abuse were compared with 50 controls born at the same maternity hospital. Five factors were significantly more common in the abused group than among their controls: (a) mother aged under 20 at birth of first child, (b) evidence of emotional disturbance, (c) referral of family to hospital social worker, (d) baby's admission to special care baby unit, (e) recorded concern over the mother's ability to care for child. Thirty-five of the abused group had two or more of these factors compared with only five of the control group. As these data were collected from information recorded routinely at the maternity hospital, it is possible to identify most abusing families when the child is born. Such identification must lead to a comprehensive assessment of each case followed by constructive preventive action.

Adolescent↗
PubMed1977

Erythrocyte 2,3-diphosphoglycerate in anaemic sheep.

Experimental anaemia resulted in an increase of red cell 2,3-DPG from 0.11 micronM/g Hb to 0.99 micronM in haemoglobin A sheep and from 0.21 micronM in haemoglobin B sheep. Production of haemoblobin Cas a result of anaemia was confined to haemoblobin A only. The results, therefore, appear to suggest that the rise in 2,3-DPG in the red blood cells of different haemoblobin types is independent of haemoblobin C.

Anemia↗
PubMed1977

Biochemical changes in the central nervous system with age in the rat.

Studies dealing with biochemistry of the central nervous system of rats have been reviewed. Data on the effects of age on enzyme activity and cellular substrates have been summarized in tabular form. In general, it can be concluded that biochemical functions dealing with anabolism decrease whereas those dealing with catabolism increase as aging progresses.

Aging↗
PubMed1977

Age changes in the neuromuscular system of rats.

Data relating to the effects of aging on the neuromuscular system of rats have been reviewed and summarized. Age effects of muscle, nerve and neuromuscular junction are presented only in a descriptive, qualitative manner, primarily due to paucity of well controlled experimentation in this area. Certain morphological and biochemical changes taking place with aging of the neuromuscular system are discussed, but no conclusive hypotheses can be presented at this time explaining diminution of motor activity in old animals.

Aging↗
PubMed1977

The Credit-Incentive system: motivating the participation of patients in a day hospital.

The Credit-Incentive System, a modified token economy, is a means of motivating the participation of day hospital patients in therapeutic activities through the use of contingent rewards. Credits are earned by patients for engaging in a wide variety of prosocial tasks and activities and can be spent for coffee, a free lunch, special time with professional staff, recreational events, and time off from the treatment centre. The receipt of credits is accompanied by social approval and recognition from the staff and other patients. Evaluations have shown that the credit system doubles the participation rate of patients in a partial hospitalization programme. The system also enhanced group cohesiveness, provides practice and feedback for cognitive re-integration, and offers opportunities of learning self-management. The results of two experiments suggest that the symbolic and social rewards mediated by the credits are the most important components of their effectiveness.

Adolescent↗