Biomedical subjects
J Cowan
Publications and source records attributed to J Cowan.
Time for a stock-aid.
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Pressor inhibition of angiotensin-induced ACTH secretion.
We investigated whether the pressor effects of systemically administered angiotensin II (AII) influence ACTH secretion. Adrenalectomized barbiturate-anesthetized mongrel dogs with constant low resting cortisol concentrations due to slow constant cortisol infusion received either bolus injections (2.5 micrograms kg-1) or 15-min i.v. infusions of a low dose (12.5 ng kg-1min-1) of AII during which blood samples were taken for ACTH and cortisol determinations. In sequential continuous experiments in each dog, blood pressure was allowed to increase in response to AII administration or was controlled by means of concurrent i.v. injections or infusions of the hypotensive drug papaverine, or by blood withdrawal from the vena cava. When the arterial pressure rise induced by AII was substantially attenuated or prevented by papaverine administration or blood withdrawal, mean ACTH secretion rates increased 400-800% and mean ACTH concentrations increased by 280-500%. On the other hand, AII administration alone caused large increases in mean arterial blood pressure but did not increase ACTH secretion significantly above control levels. These data suggest that when endogenous AII levels are elevated without a concurrent increase in blood pressure, as occurs during hypovolemia or sodium depletion, AII may have a significant influence on ACTH secretion.
Preoperative ranitidine and metoclopramide.
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Reproductive patterns and thalassaemia major.
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Variable distributions of serum creatine kinase reference values. Relationship to exercise activity.
Although the effect of exercise on serum creatine kinase (CK: EC 2.7.3.2) activity is well known, no standard protocol for blood collection conditions has been developed. Variable frequency distributions of CK activities have been reported for reference range samples from different laboratories and have been attributed to laboratory differences. In this study the frequency distributions of creatine kinase activities (CK: EC 2.7.3.2) in serum samples obtained from the same groups of volunteers varied from a normal Gaussian distribution, to skewed distributions, on different occasions. In one collection extremely high CK values followed the performance of an eccentric exercise step test 5-8 days previously. In 2 students serum CK activities had not returned to resting values 12 and 15 days later. Peak serum CK values occurred within 24 h of other types of exercise. Serum CK frequency distributions in blood samples obtained from a group of nurses was skewed, whereas the distribution in mothers of school children was Gaussian. When repeat samples were obtained from the nurses after instruction to avoid exercise, the distribution became Gaussian. In view of the increasing levels of physical activity in the community, a standard protocol for serum CK analysis is required, in which exercise activity over the previous three weeks should be documented. Test subjects should be counselled to avoid unusual eccentric exercise and sampling should include 3 tests at least 1 week apart.
Incidence of homozygous beta-thalassaemia in New South Wales, 1961-1976.
A case-finding survey yielded 58 persons with transfusion-dependent homozygous beta-thalassaemia who lived either in New South Wales or in the Australian Capital Territory. Of those born between 1961 and 1976 in New South Wales, nearly 70% were of Greek or Greek-Cypriot origin and 18% of Italian origin. The New South Wales incidence rates for homozygous beta-thalassaemia were estimated as follows: one in 934 births, Greek origin; one in 264 births, Cypriot origin and one in 3441 births, Italian origin.
The specific inhibition of cellular clonogenic proliferation using 211At labelled lectins and antibodies--I.
A monoclonal antibody with a broad anti-human leucocyte specificity, designated BK 19.45 and the plant lectin Concanavalin A have been labelled with the alpha-emitting cyclotron produced radiohalogen astatine-211. Both human and murine tumour cell lines and human leukemic bone marrow samples have been specifically labelled with these radioactive proteins. In all cases the amount of 211At bound to the cells is directly correlated with a decrease in cellular reproductive potential as shown by the ability of the cells to proliferate in a clonogenic assay. For the labelled monoclonal antibody experiments, the radiation dose needed to yield 37% cell survival, the D37 dose, may be achieved with an average of 12 211At atoms/cell.
Marijuana and memory for feelings.
1. This experiment tested the hypothesis that marijuana intoxication results in an impaired memory for feeling states. 2. Marijuana intoxication during memory testing--that is, after the subjects had observed and recorded their feelings, decreased accuracy of memory for feelings of fatigue, as measured by the Profile on Mood States (POMS). 3. Marijuana given prior to the period of self-observation, impaired accuracy of memory for feelings as measured by several POMS scales.
Health visiting and the nursing process. II. Putting the health visiting process into practice.
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Human tumor cloning: feasibility and clinical correlations.
The human tumor cloning system is a soft agar technique which allows the growth of human tumors in vitro. We report here our experience with culturing 2,365 patients' tumors in the system. Overall 1,844 (78%) have formed colonies in vitro. However, only 51% have formed greater than or equal to 30 colonies per 500,000 cells plated. Despite the limitations of inadequate growth for some tumors there are a number of clinical applications for the system, which are reported here. These include: (1) Use of the system to predict for sensitivity of an individual patient's tumor to a particular chemotherapeutic agent; (2) screening new anticancer agents to predict for in vivo activity; 3) monitoring patients' bone marrows for tumor involvement; and (4) use of the number of colonies which form in the assay as a prognostic factor for survival. All of these clinical applications are in their infancy of development and will require carefully designed prospective trials to determine the final place of the human tumor cloning system in the practice of clinical oncology.
A report on student health services.
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Incidence of Duchenne muscular dystrophy in New South Wales and Australian Capital Territory.
A survey was conducted during 1977 to 1978 to determine the incidence of Duchenne muscular dystrophy in New South Wales and the Australian Capital Territory. Ninety-nine cases born between 1960 and 1971 were ascertained representing an incidence rate of 18.6 per 100 000 liveborn males. Over 60% of the ascertained males were isolated cases, and only 7% of affected males had an affected males relative in a previous generation in the female line. Categorisation of ascertained cases as either "theoretically preventable" or not shows that genetic counselling alone in the present circumstances is insufficient to reduce the incidence rate significantly.
Cyanide toxicity following nitroprusside induced hypotension.
Several recently reported deaths following the use of sodium nitroprusside have been attributed to the accumulation of the nitroprusside metabolite, cyanide. In this study, brief nitroprusside infusions (mean = 36 minutes) were administered in currently recommended doses during intracranial surgery. The peak blood cyanide following the infusions was 65.2 +/- 17.5 microgram per cent (mean +/- SE) (n = 13). It occurred within 45 minutes after infusion. The highest cyanide level detected was 205 microgram per cent, which is within the range of reported lethal blood cyanide levels. Metabolic acidosis developed in the four patients with the highest blood cyanide levels (range 90-205 microgram per cent). This occurred between 45 and 180 minutes following the cyanide peak. Blood ATP levels were depressed in the same patients. These findings are indicative of disturbed aerobic metabolism. We conclude that there is evidence of cyanide toxicity when nitroprusside is infused into patients using currently recommended doses. We recommend that for short infusions the dose of sodium nitroprusside should not exceed 0.5 mg/kg.
Absorption of crystalline folic acid in man.
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Drug dependence in a journal club.
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