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Biomedical subjects

M C Browning

Publications and source records attributed to M C Browning.

At least 55 records · Page 3Linked to original sources
PubMed1985

The clinical and metabolic responses to early surgical treatment for hyperthyroid Graves' disease: a comparison of three pre-operative treatment regimens.

We have compared the clinical and metabolic responses of three groups of patients undergoing subtotal thyroidectomy for hyperthyroid Graves' disease. These patients were prepared for surgery with propranolol alone, propranolol plus potassium iodide or the long acting beta-adrenoceptor antagonist nadolol plus potassium iodide. Pre-treatment with potassium iodide reduced serum T4 to normal or subnormal in all patients. Patients in the propranolol group had significantly higher pulse rates and temperatures after operation and one patient developed an exacerbation of the hypermetabolic state. The perioperative rise in serum cortisol and blood glucose was delayed in patients in the propranolol group and this was also noted in one severely hyperthyroid patient on propranolol + potassium iodide. Nadolol was administered once daily as compared to multiple daily doses with propranolol. Despite this, plasma nadolol levels were consistently higher throughout the perioperative period while propranolol levels in patients on both propranolol alone and propranolol + potassium iodide were highly variable and sometimes undetectable. We conclude that, in the rapid preparation of patients with hyperthyroid Graves' disease for surgery, the combination of nadolol + potassium iodide has significant advantages over the other two regimens.

Adult↗
PubMed1984

Intrarenal aneurysm of the renal artery in children.

Two children with hypertension had intrarenal aneurysms in the renal artery. In both children, renovascular hypertension was documented by renal vein renin assay showing elevated renin secretion from the involved kidney and suppression of renin secretion from the contralateral kidney. Transcatheter embolization of a segmental artery cured the hypertension in one case. A nephrectomy performed in the other case, because of multiple intrarenal aneurysms, was curative. Intrarenal renal artery aneurysms are an uncommon cause of renovascular hypertension in children. The aneurysms may be mycotic or congenital in origin, or secondary to diffuse vasculitis. Although spontaneous resolution of the aneurysms may occur when due to vasculitis, treatment of most aneurysms is usually necessary. Transcatheter embolization of solitary aneurysms is an attractive alternative to partial nephrectomy, since it allows maximal preservation of renal parenchyma with minimal morbidity.

Aneurysm↗
PubMed1983

The sensitivity of peripheral blood lymphocytes to growth inhibition by hydrocortisone is not determined by their OKT4:OKT8 ratio.

Normal adult human subjects show considerable variation in sensitivity to depression of the activation phase of mitogen-induced lymphocyte growth by the natural glucocorticoid, hydrocortisone. In a study of 21 subjects, the slope of the log-dose response to hydrocortisone was unrelated to the relative numbers of cells in the two major T-cell subpopulations stained by the OKT4 and OKT8 monoclonal antibodies. It is concluded that the extent of the glucocorticoid-induced suppression of early mitogen-stimulated lymphocyte growth is probably not determined by relative numbers of the various immunoregulatory lymphocytes.

Adult↗
PubMed1983

Interaction of ischemic and antibiotic-induced injury in the rabbit kidney.

The tubular necrosis produced by transient unilateral ischemia, three toxic cephalosporins, and the aminoglycoside neomycin were studied separately and in different combinations in the rabbit kidney. It was found that (1) mildly damaging transient ischemia (25 min) and a minimally toxic dose of the rapidly secreted cephalosporin cephaloglycin (60 mg/kg of body weight) are synergistically damaging; (2) there is no synergy between ischemia and the nonsecreted cephalosporin cephaloridine (90 mg/kg); and (3) ischemia and neomycin (100 mg/kg per day for three days) are not additively damaging, but the aminoglycoside has an additive effect with the combined insults of ischemia and cefazolin (500 mg/kg). Studies of transport showed that ischemia potentiates cephalosporin toxicity probably because it increases postischemic antibiotic concentrations in proximal tubular cells and that this increased uptake is the result of transiently augmented tubular secretion. Although this ischemic protocol reduced inulin clearance by 40%, it increased cephaloglycin secretion by an amount more than sufficient to overcome the decrease in filtration.

Acute Kidney Injury↗
PubMed1983

Reactivity and binding of beta-lactam antibiotics in rabbit renal cortex.

In studies designed to evaluate the reactivity of the beta-lactam antibiotics in the rabbit kidney, the binding to cortical macromolecules of isotopically labeled cephaloglycin (highly toxic) was compared in vivo and in vitro with that of cephalothin (minimally toxic) and benzylpenicillin (nontoxic). Three hours after administration of equal doses, the amounts of firmly bound antibiotic in whole cortex and in nuclear, mitochondrial, microsomal and cytosolic fractions of cortex were greatest for cephaloglycin (cortical concentration 7% of that measured at 0.5 hr), intermediate for cephalothin (2%) and least for benzylpenicillin (1%); the amounts of firmly bound antibiotic were unrelated to the earlier, peak cortical concentrations. Binding to cortical microsomes in vitro showed a similar pattern (greatest for cephaloglycin, least for benzylpenicillin); in addition, the binding in vitro of cephaloglycin was decreased by the addition of an NADPH-generating system and was not decreased by piperonyl butoxide. These studies provide evidence that the spontaneous reactivity of the beta-lactam ring may be an important determinant of the nephrotoxicity of the cephalosporins and fail to support the existence of a role of the cytochrome P-450 mixed-function oxidases in this reactivity.

Animals↗
PubMed1982

Nadolol and potassium iodide in combination in the surgical treatment of thyrotoxicosis.

With the two aims of rapidly reducing circulating thyroid hormone levels and controlling the symptoms of thyrotoxicosis, we have prepared 17 thyrotoxic patients for subtotal thyroidectomy, using a combination of potassium iodide administered for 10 days and the long acting beta-adrenoceptor antagonist nadolol. All 17 patients had normal serum thyroxine levels after 10 days of such treatment although 10 still showed elevation of serum tri-iodothyronine and considerable elevation in the most severely toxic patient. All patients were, however, clinically euthyroid preoperatively. Nadolol was administered once daily, hence avoiding the problems of drug administration in the immediate postoperative period, and plasma nadolol concentrations were high throughout the perioperative period. Serum thyroxine and tri-iodothyronine levels were significantly lower and reverse tri-iodothyronine levels higher 24 h postoperatively than before operation. All patients remained stable throughout the perioperative period. We conclude that this regimen has a number of advantages in the preparation of patients for thyroidectomy, in reducing the degree of thyrotoxicosis, in convenience of drug administration and in ensuring adequate circulating concentrations of beta-adrenoceptor antagonist whilst still retaining a relatively short preoperative phase of drug treatment.

Adrenergic beta-Antagonists↗
PubMed1982

Prevention of cephalosporin nephrotoxicity by other cephalosporins and by penicillins without significant inhibition of renal cortical uptake.

Prevention of cephalosporin nephrotoxicity in animal models by probenecid or p-aminohippurate requires treatment regimen that produce sustained inhibition of cortical accumulation of the toxic antibiotic. In contrast, cephaloridine nephrotoxicity in the rabbit can be prevented by a limited single dose of cephalothin. In the present report further studies were done in which it was demonstrated that cephaloridine nephrotoxicity can be prevented by doses of other cephalosporins or penicillins that produce little or no reduction of the cortical concentrations of toxic cephalosporin. More limited studies revealed similar protection by benzylpenicillin against cephaloglycin, also without reduction of cortical concentration. Finally, similar limited-dose administration of penicillin eliminated tha additive toxicity of cefazolin and neomycin. This selective protection against the toxic cephalosporins by the less toxic or nontoxic cephalosporins and by the penicillins, without inhibition of overall cortical accumulation of the toxic antibiotic, may provide a subcellular probe for the study of the molecular basis of cephalosporin nephrotoxicity.

Animals↗
PubMed1982

Adrenocortical suppression in workers employed in manufacturing synthetic glucocorticosteroids: solutions to a problem.

Earlier studies showed gross adrenocortical suppression in three workers employed in manufacturing synthetic glucocorticoids. A further nine had either recognisable abnormalities of their responses to tetracosactrin or evidence of chronic skin contact with glucocorticoids. By 1978 the mean morning cortisol concentration of 20 workers employed in active steroid processes was 235 nmol/1 +/- 28.6 (8.5 microgram/ml +/- 1.04), which was significantly lower than the value of 428 nmol/l +/- 37.7 (15.5 microgram/ml +/- 1.40) obtained in a control group of 19 men (p less than 0.005). The mean morning cortisol of workers employed in processing steroids believed to be physiologically inactive, 306 nmol/l +/- 22.4 (11.1 microgram/ml +/- 0.81), was also significantly lower than this control group (0.01 greater than p greater than 0.005). Improvement of protection for workers together with operational and plant changes resulted in a significant rise in the mean morning cortisol values of workers until, in 1979, men employed in all steroid processes had concentrations that did not differ from those of a control group.

Adrenal Cortex Diseases↗
PubMed1981

Altered endocrine response to partial thyroidectomy in propranolol-prepared hyperthyroid patients.

The endocrine response to partial thyroidectomy in a group of twenty hyperthyroid patients prepared with propranolol alone was compared to that of a matched control group of ten euthyroid patients. In propranolol-prepared patients the glucose response to surgery was reduced (P less than 0.05) for up to 4 h post-operatively and biochemical hypoglycaemia was noted in one patient. Both thyroxine and triiodothyronine (T3) fell significantly, associated with a marked rise in reverse T3. Growth hormone levels were higher (P less than 0.05) both pre- and post-operatively in propranolol-prepared patients, whereas prolactin levels, although similar pre-operatively, were lower (P less than 0.05) in these patients post-operatively. Cortisol and ACTH levels were lower (P less than 0.05) both before and following thyroidectomy in propranolol-prepared patients. These results suggest that the endocrine response to surgical stress is markedly altered in propranolol-prepared hyperthyroid patients.

Adrenocorticotropic Hormone↗
PubMed1981

Effects of two histamine H2-receptor blocking drugs on basal levels of gonadotrophins, prolactin, testosterone and oestradiol-17 beta during treatment of duodenal ulcer in male patients.

In a study of 51 male patients with duodenal ulcer, treatment with cimetidine was accompanied by an increase in basal levels of serum testosterone. Treatment with ranitidine, a new histamine H2-receptor antagonist, produced no such effect. It is concluded that cimetidine had antiandrogenic activity in man which is separate from the histamine H2-receptor blocking activity.

Adult↗
PubMed1981

Clinical and endocrine aspects of treatment with ranitidine.

Ranitidine has been shown to heal the majority of duodenal ulcers during treatment with 300 or 320 mg daily for 4 to 8 weeks. Twice-daily dosage improved compliance. Subsequent maintenance treatment with ranitidinie, 150 mg at night prevented relapse in the majority of patients during 6-months' follow-up. Ranitidine did not appear to have any anti-androgenic effects.

Administration, Oral↗
PubMed1981

The effect of strenuous physical exercise on circulating blood lymphocytes and serum cortisol levels.

Venous blood was removed from healthy subjects immediately before and at intervals after exercise on a bicycle ergometer. Immediately after exercise, the subjects developed a lymphocytosis in which (a) the E-rosette percentage fell by 10% but their absolute number in the circulating blood rose by more than 70%, (b) the percentage of PHA-stimulated cells fell, but their absolute numbers increased considerably and (c) the absolute numbers of Con A- and PWM-responding cells increased. The numbers of lymphocytes in the various subpopulations had returned virtually to the pre-exercise levels 15 minutes after stopping exercise. During the response to exercise, the characteristics of the cells in the various subpopulations did not show any major changes, despite considerable and rapid fluctuations in numbers: it is suggested that exercise discharges intravascularly sequestered cells and that cortisol may be involved in re-sequestration of stress-released cells. It is recommended that, in clinical studies on circulating lymphocyte numbers and populations, the patient should be rested for at least 15 minutes before venesection.

Adolescent↗