Biomedical subjects
B McGrath
Publications and source records attributed to B McGrath.
Plasma catecholamines and the pressor response to saralasin.
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Plasma renin activity, plasma angiotensin II and extracellular fluid volume in patients after renal transplantation.
1. Patients with cadaveric renal transplants and plasma creatinine less than 177 micronmol/l who had their own kidneys removed were studied. 2. The renin-angiotensin system appeared to behave in a normal fashion in response to alterations in sodium intake and posture. 3. The renin-angiotensin system had no major role in the establishment or maintenance of hypertension. 4. Mean arterial pressure was directly related to expansion of the extracellular fluid volume.
Medico-legal problems. Medico-legal aspects of the student health service.
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Effects of dopamine on renal function in the rat isolated perfused kidney.
The renal effects of dopamine, the dopamine antagonist spiperone and the combination of dopamine and spiperone were examined in the isolated perfused rat kidney preparation. Studies were carried out at constant perfusion pressure and the following were measured at 10 min intervals for 1 h: perfusate flow; GFR (3H-inulin); urine flow rate; sodium, potassium and kallikrein excretion; perfusate renin concentration; perfusate and urinary-dopamine levels. Low-dose dopamine infusion (6 X 10(-10) mol/min) resulted in significant diuresis, natriuresis and kaluresis but little change in GFR. These effects were blocked by spiperone (10(-10) mol/min) which had no significant effects when infused alone. At a higher dose (10(-8) mol/min) dopamine significantly increased urine flow alone; this too was reversed by spiperone. Dopamine had no significant effects on perfusate flow, renin release or kallikrein excretion. Perfused control kidneys excreted amounts of dopamine (328 pmol/h, s.e.m. = 57, n = 6) far in excess of kidney dopamine content (49 pmol/g, s.e.m. = 6, n = 32). Renal handling of infused dopamine was dose-related; the fraction of the administered dose taken up and/or metabolized by the kidney on the higher dose infusion was considerably less than on the lower dose (40%, s.e.m. = 3 vs. 82%, s.e.m. = 6) while more was excreted (13%, s.e.m. = 3 vs. 2%, s.e.m. = 1). These studies indicate that dopamine at low doses can produce diuresis, natriuresis and kaluresis independently of extrarenal or haemodynamic influences and not mediated by renal renin or kallikrein systems. The kidney also exhibits a saturable capacity for dopamine uptake and/or metabolism.
Australian doctors and their postgraduate qualifications.
BACKGROUND: A key activity for doctors is lifelong learning. This may be as part of professional development, vocational registration, formal postgraduate study, e.g. university diplomas and degrees, or vocational training which leads to fellowship of a professional college. However, there are significant barriers of time and cost that prevent many doctors from participating in lifelong learning. METHOD: We examined the range of basic and postgraduate qualifications held by a representative sample of 1198 doctors provided by the HIC of Australian doctors. DISCUSSION: Significant numbers of general practitioners practise without a formal postgraduate qualification in general practice, unlike our specialist colleagues. However, postgraduate studies are undertaken in a variety of other formats and qualifications.
In vivo catecholamine extraction during continuous hemodiafiltration in inotrope-dependent patients.
Many critically ill patients require inotropic or vasopressor support to maintain adequate oxygen delivery. Removal of catecholamines by continuous hemodiafiltration (CHD) could alter exogenous catecholamine requirements. The authors have studied hemodynamic state, catecholamine clearances, and catecholamine requirements in 12 critically ill patients (mean APACHE II score, 24.5) receiving CHD. Hemodynamic parameters were assessed before CHD initiation, and at 4 and 24 hours of therapy. Simultaneous determinations of serum and ultradiafiltrate dopamine (D), norepinephrine (NE), and epinephrine (E) concentrations were obtained. There were no significant changes in any of many hemodynamic parameters measured during CHD. Mean catecholamine requirements were not altered by CHD. Plasma catecholamine levels were not significantly affected by CHD (mean values at 0, 4, and 24 hours: D: 10,801, 12,056, and 8,797 pg/ml; NE: 1124, 566, and 926 pg/ml; E: 1,420, 1,383, and 843 pg/ml). Catecholamine clearances from CHD (D:43.7 ml/min; NE: 43.5 ml/min; and E: 46.6 ml/min) resulted in daily excretion of only 379 micrograms D, 32.9 micrograms NE, and 37.2 micrograms E. Clearances of catecholamines by CHD represented a daily loss of less than 0.1% of the administered load. In conclusion, although CHD can remove circulating catecholamines, cumulative daily catecholamine extraction is minimal in pharmacologic terms, and has no impact on hemodynamic status.
Juvenile chronic arthritis.
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