Search PubMed⌕ Search

Biomedical subjects

R Clark

Publications and source records attributed to R Clark.

At least 361 records · Page 20Linked to original sources
PubMed1979

Thrombosis: a study of coagulation parameters and mechanisms during allograft rejection.

Thrombosis of the microvasculature has been recognized at the end product of organ rejection, but the exact biological pathway through which this occurs has not been clarified. Normal, factor VII deficient and heterozygous hemophilic (factor VIII) dogs were grouped to study the intrinsic and extrinsic clotting and platelet mechanisms during unmodified renal allograft rejection. The observed alterations of the hemostatic mechanisms are related to the changes observed in the microvasculature. Six groups of donor-recipient animals were studied: Group I -autografts (control); Group II - normal to normal allografts with bilateral nephrectomy; Group III - heterozygotes for factor VIII deficiency; Group IV - normal to normal allografts with unilateral nephrectomy; Group V - normal to factor VII deficiency without nephrectomy; and Group VI - normal to normal allografts with unilateral nephrectomy and dipyridamole. Each engrafted animal was followed pre- and posttransplantation for change in the blood clotting factors, fibrin split products, platelets, white blood cells, renal function and microvasculature. The animals with factor VII deficiency rejected in a similar fashion as the control animals. The group with impaired factor VIII synthesis and platelet function had longer survival times. These data suggest that the intrinsic clotting pathway and platelets are the primary mechanism through which thrombosis occurs secondary to immune injury.

Animals↗
PubMed1979

Demonstration of two new endogenous "benzodiazepine-like" compounds from brain.

The recent report that purines are competitive inhibitors of specific [3H] diazepam binding to brain membranes has prompted further work concerning the characterization of possible endogenous ligands for the benzodiazepine receptor. In this report, two previously undescribed fractions capable of apparent competitive inhibition of [3H] diazepam binding are reported. Both factors are heat stable and resistant to proteolytic degradation. The larger factor (approximately 700 to 30,000 daltons) is present only in brain and pituitary. The smaller factor (500 to 600 daltons) is found in pituitary, liver, and muscle, but the highest levels are found in brain.

Animals↗
PubMed1979

Psychological aspects of dialysis: a semantic differential study.

As a consequence of technological advances over the last 15 years, patients suffering from terminal renal failure are now being kept alive for considerable periods of time, either by renal haemodialysis or, where appropriate and possible, by renal transplantation. The former necessarily imposes restrictions on the patients' lives which may be manifest at various levels. The basic aim of the study to be reported was to conduct an exploratory investigation of the psychological impact of dialysis on such patients, together with some of the factors that may influence their reactions to it. Using a Semantic Differential technique, 21 patients on dialysis were compared with a group of 21 healthy control subjects in terms of the personal meaning of selected concepts. Both groups were then subdivided on the basis of age, sex and, in the case of the patients, in terms of length of time on dialysis. Subgroup comparisons were then conducted. The findings suggest various hypotheses which have both theoretical and clinical implications.

Adult↗
PubMed1979

Modulation of the susceptibility of inbred and outbred rats to arthritis induced by cell walls of group A streptococci.

Inbred Buffalo rats were resistant to the induction of experimental arthritis induced by systemic injection of cell wall fragments in a crude whole-cell sonic extract of group A streptococci. This was in contrast to the susceptibility of outbred Sprague-Dawley and certain other inbred strains. Preliminary breeding studies indicated that genetic control of resistance of susceptibility is multigenic. When Buffalo rats were infected with a saline suspension of isolated cell wall fragments, chronic remittent arthritis developed. Suspension of isolated cell wall fragments, chronic remittent arthritis developed. Suspension of the isolated cell walls in the supernatant fraction of group A streptococci solubilized by sonication eliminated the arthropathogenicity in Buffalo rats. Thus, a component separable from the cell wall fraction can modulate the arthropathogenicity of cell walls in rats, but the effect depends upon the genetic background of the rat. The antibody response of Buffalo rats to the polysaccharide antigen of cell walls was also affected by the supernatant fraction of sonicated group A streptococci.

Animals↗
PubMed1979

Infant feeding and overweight in two Oxfordshire towns.

In a study of feeding and growth in the first year of life in two Oxfordshire market towns, the frequency of overweight babies was the same for the 'intervention' town (where a research health visitor gave intensive advice to mothers on feeding) as for the control town. Eighteen per cent of bottle-fed infants and three per cent of those breast fed were overweight at one year. It seems that an increase in the number of health visitors does not affect the frequency of overweight infants, but it may be that a greater emphasis on breast feeding might reduce the frequency.

Bottle Feeding↗
PubMed1978

A new variant of methylmalonic acidemia-defective coenzyme-apoenzyme binding in cultured fibroblasts.

Cultured fibroblasts from a patient with methylmalonic acidemia, clinically responsive to vitamin B-12, were studied in vitro. Kinetic analysis revealed abnormal binding of the coenzyme, 5'-deoxyadenosylcobalamin, for its methylmalonyl-CoA carbonylmutase apoenzyme, i.e., KM of 3.8 X 10(-5) M versus control KM of 1.5 X 10(-8) M. These data are interpreted as indicating a structural defect of the apoenzyme at the coenzyme binding site, and represent another variant of this genetic disorder.

Amino Acid Metabolism, Inborn Errors↗
PubMed1977

Noncirrhotic portal hypertension in Felty's syndrome.

A case of Felty's syndrome with nodular regenerative hyperplasia of the liver, presinusoidal portal hypertension, and bleeding esophageal varices is reported. Increased splenic blood flow may be a contributing factor to the development of the regenerative nodules. The portal hypertension is postulated to be a result of intrahepatic vascular compression.

Esophageal and Gastric Varices↗