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Biomedical subjects

C Hawkey

Publications and source records attributed to C Hawkey.

At least 37 records · Page 2Linked to original sources
PubMed1985

Role of calcium in the induction of cardiac hypertrophy and myofibrillar disarray. Experimental studies of a possible cause of hypertrophic cardiomyopathy.

The role of calcium in the pathogenesis of hypertrophic cardiomyopathy was investigated experimentally. For this purpose the calcium antagonist verapamil and the calcium ionophore A23187 were administered to pregnant rats together with triac in order to observe their effect on triac induced myocardial disarray and hypertrophy in developing rat hearts. At a low dose verapamil reduced both the level of disarray and hypertrophy, but a higher dose produced hypertrophy when given alone. A23187 did not appreciably potentiate the actions of triac when given in combination but when administered alone produced both disarray and hypertrophy. Verapamil prevents the inward movement of calcium ions to the myocardial cell, whereas A23187 increases the inflow of calcium ions. The results suggest that the actions of triac in producing myocardial disarray and hypertrophy are attributable to an increased concentration of intracellular calcium.

Animals↗
PubMed1985

A phylogenetic study of the structural and functional characteristics of corticosteroid binding globulin in primates.

A monospecific antiserum against human corticosteroid binding globulin (hCBG) has been used to identify structural similarities between hCBG and CBG in the blood of other primates and representative species of different vertebrate classes. Double immunodiffusion analysis indicated that only CBG in Old World monkeys and apes cross-react with the hCBG antiserum. This was confirmed by a solid-phase radioimmunoassay for hCBG which also demonstrated that CBG in apes is immunologically identical to hCBG and that Old World monkey CBG comprises most, but not all, of the hCBG epitopes. The electrophoretic mobilities of human, gorilla and gibbon CBG were similar (RF 0.50-0.51), but differed from Old World monkey CBG (RF 0.44-0.49) and chimpanzee CBG (RF 0.47). Although serum/plasma cortisol binding capacities were similar in Old World primates, the dissociation half-times (t 1/2) of cortisol were higher from human and ape CBG (18-25 min) than from Old World monkey CBG (14-18 min). The steroid binding specificities of human and ape (CBG corticosterone greater than cortisol greater than progesterone greater than or equal to testosterone) were also different from those of Old World monkey CBG (corticosterone much greater than cortisol approximately equal to progesterone greater than testosterone). Lemur plasma cortisol binding capacity and CBG dissociation t 1/2 of cortisol were similar to hCBG, but its steroid binding specificity was different (cortisol greater than corticosterone greater than progesterone greater than or equal to testosterone) and it did not cross-react with the hCBG antiserum.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1982

Immunologic studies of factor VIII coagulant activity (VIII:C). 2. Factor VIII in selected vertebrates.

Cross reactive antigens to factor VIII have been measured in a range of vertebrate phyla. VIII coagulant antigen (VIII:CAg) measured using a human antibody was in general, much lower than reported values of VIII coagulant activity (VIII:C) except in simians and the guinea pig. The dose response curve for the assay was parallel in all cases. Factor VIII-related antigen (VIIIR:Ag) measured using rabbit antibody to human VIIIR:Ag was low or absent in most species except simians and the dose response curve was non-parallel to the human standard except with goat plasma. Avians lacked cross-reactive material.

Animals↗
PubMed1977

Effect of triac on the developing heart.

Triac (diethanolamine salt of triiodothyroacetic acid) was administered by intramuscular injection to 12 pregnant female rats. These were divided into a control group and three other groups, each receiving different doses of triac. The effect of triac on the hearts of their offspring was studied morphologically. Histological examination showed evidence of only mild hypertrophy, but ultrastructurally, disarray of myocardial fibrils and other changes similar to those observed in patients with hypertrophic cardiomyopathy were found in the litter of the group receiving the highest dose. It is suggested that thyroid function should be studied in patients with obscure cardiac disease.

Animals↗
PubMed1976

The effect of beta adrenergic blockade upon exercise-induced changes in blood coagulation and fibrinolysis.

Exercise stress is known to stimulate blood coagulation and fibrinolysis possibly as a result of sympatho-adrenal stimulation of the beta adrenergic receptor. In order to test this hypothesis five men exercised on four separate occasions with and without prior beta adrenergic blockade with oxprenolol, propranolol and pindolol. The increase in plasma adrenaline and noradrenaline concentration was much greater during exercise under beta blockade but activation of fibrinolysis was enhanced as well. Factor VIII levels did not change significantly during any of the experiments. These results suggest that the activation of fibrinolysis by exercise is not mediated by the beta adrenergic receptor. The influence of beta adrenergic blockade on the change in factor VIII with exercise was inconclusive.

Adrenergic beta-Antagonists↗
PubMed1976

The coagulation and fibrinolytic response to splenectomy.

The responses of the coagulation and fibrinolytic systems in nine patients with Hodgkin's disease undergoing splenectomy and lymph node mapping have been compared with those in nine patients undergoing elective upper abdominal operation for benign conditions. Differences have been noted in base line levels of fibrinogen, prothrombin, partial thromboplastin time and euglobulin lysis time. Platelet count increases were exaggerated following splenectomy, but other parameters of coagulation activity behaved similarly in the two groups. There is no evidence from this study to support the suggestion that blood coagulability is increased more markedly following splenectomy than it is after other upper abdominal operations.

Abdomen↗
PubMed1975

The influence of beta-adrenergic blockade upon baseline blood coagulation and fibrinolytic activity and upon the responses to venous occlusion.

Twenty volunteers were assessed for baseline coagulation (Thrombelastography, Factor VIII and platelet count) and fibrinolytic (Euglobulin Lysis Time and Fibrin(ogen) Degradation Products) activity two hours after ingestion of 60 mgm propranolol or an identical placebo administered on a double blind basis. The responses of these parameters to a fifteen minute period of venous occlusion was also assessed. Beta adrenergic blockade reduced baseline FDP titres but did not affect other parameters, nor the local response to venous occlusion. During occlusion no significant change in coagulation activity could be detected in the non-occluded arm, but a small but statistically significant shortening of ELT was observed. Since this effect was prevented by propranolol it is probably mediated through adrenergic mechanisms. Adrenergic stimuli appear to influence episodes of coagulation and fibrinolysis during everyday activity, but do not contribute to baseline levels of coagulation or fibrinolytic function.

Adult↗
PubMed1974

Adrenergic, coagulation, and fibrinolytic responses to heat.

Two groups of volunteers were exposed to heat in a sauna bath-one group for 10 minutes and the other for 15. There was no change in plasma adrenaline concentration until the subjects emerged from the sauna bath, when there was a slight increase in concentration. Factor VIII and thrombo-elastograph patterns did not change but marked activation of fibrinolysis was stimulated by exposure to heat. These findings support the concept that fibrinolysis is not mediated by direct adrenergic activity.

Adult↗
PubMed1971

A laboratory study of spontaneous platelet aggregation.

During studies on platelet aggregation using the EEL platelet aggregation meter, 8% of the individuals tested were found to have platelets which aggregated spontaneously when citrated, platelet-rich plasma was stirred at 37 degrees C. The EEL aggregation meter differs from other machines in that it incorporates a vertical stirrer which subjects platelets to greater mechanical force. When using this machine it is suggested that spontaneous platelet aggregation is related to increased mechanical fragility of the platelets and low levels of plasma ADP-inhibitor.

Adenine Nucleotides↗