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Biomedical subjects

F O Simpson

Publications and source records attributed to F O Simpson.

At least 73 records · Page 4Linked to original sources

Review of long-term treatment with labetalol.

1 Labetalol has been used to treat 163 patients at the Dunedin Hypertension Clinic for periods up to 6.5 y, and of 128 patients in a New Zealand multicentre study for 2 yr. 2 Labetalol was often effective when other anti-hypertensive agents, including beta-blockers, had failed. It was usually given with a diuretic. 3 Mean daily dose was 700 mg (range 100-2400 mg). No tolerance to the anti-hypertensive effect was seen. 4 Some postural-induced decrease in blood pressure on labetalol was common. 5 Side-effects led to withdrawal of labetalol in about 25% of patients, mainly during the first few months of therapy. Another 25% had minor side-effects but could continue with the drug. 6 There were three types of side-effects (in order of frequency): (a) non-specific, (b) related to alpha-blockade and (c) related to beta-blockade. The latter were much less troublesome than on "pure" beta-blockers. 7 There was no significant evidence of renal haematological or hepatic toxicity. 8 Anti-nuclear antibody tests became positive on labetalol in about 15%, usually at low titres but in one patient the titre increased to a high level and fell when labetalol was stopped. 9 In a subset of 25 patients who took labetalol for the longest time (up to 6.5 yr) there was a 16% incidence of anti-mitochondrial antibodies.

Adolescent↗

Effect of captopril on blood pressure, total body sodium and fluid consumption of genetically hypertensive (GH) and normotensive (N) rats.

Captopril was administered in the drinking fluid to normotensive rats and rats of the New Zealand genetically hypertensive (GH) strain. It lowered BP in both strains of rat, particularly in rats deprived of sodium; in these rats BP rose again when the drug was stopped even though there was no access to sodium. Thus captopril appeared to lower blood pressure not by reduction in total exchangeable sodium but by some other mechanism, presumably inhibition of vasoconstriction. Total exchangeable sodium did not change significantly in rats treated with captopril and having access to salt in the drinking fluid, though it fell in rats deprived of sodium. Captopril caused an increase in fluid intake, particularly intake of 0.5% NaCl solution and this may have compensated for any loss of body sodium. It was not clear whether the thirst for water and the desire for salt were due to effects of captopril in the CNS or were secondary to increased excretion of salt and water.

Animals↗

Cigarettes and accelerated hypertension.

The smoking and drinking habits of 58 patients with accelerated hypertension were compared with those of a control group of 58 patients with benign hypertension, each individually matched for age, sex and date of presentation. Thirty-eight (66 percent) of the patients with accelerated hypertension were regular smokers compared to 26 (45 percent) of the control group. This excess of smokers was significant, but the average number of cigarettes smoked by smokers in the two groups was similar. The number of patients known to consume alcohol was the same in the two groups; and there were no significant differences in amount of alcohol drunk. Smoking and alcohol habits were not related. Thirty-six patients (62 percent) with accelerated hypertension had serum creatinine levels greater than 0.12 mmol/l compared with nine (16 percent) of the control group. Seventeen (29 percent) patients with accelerated hypertension were known to have died compared with five (9 percent) of the control group. This survey confirms that, as shown by recent studies in Britain, smoking is more common in patients presenting with accelerated than with benign hypertension. It appears that hypertensive patients who smoke regularly are more likely to develop the accelerated phase than those who do not.

Alcohol Drinking↗

Intrarenal blood flow distribution in the genetically hypertensive rat.

Distribution of intrarenal blood flow has been measured in genetically hypertensive (GH) and normotensive (N) rats (aged 17--23 weeks) by a 133Xe washout technique without opening the abdominal cavity. Three different specific flow compartments were found in the rats. The distribution of the intrarenal blood flow to the fast compartment was reduced in the GH rats when compared with the N rats and the rate of flow in it was also reduced. The flow rate in the second compartment was the same in the two strains, the distribution to it being relatively greater in the GH rats. The mean renal blood flow index (in ml/min/g of kidney) was reduced in the GH rats. It is not at present clear whether these differences are due to the hypertension or represent a causative factor in the hypertension.

Animals↗

Age, adiposity, blood pressure and blood lipids in a rural New Zealand population.

Multiple regression analysis of data on age, blood pressure, adiposity and blood lipids from a rural New Zealand population of over 1200 adults has been undertaken. The results show that rises in blood lipids over time in the population are independent of age and correlate significantly with adiposity. Thus plasma cholesterol and triglycerides correlate with adiposity (expressed as Quetelet's index or skinfold thickness) in men whereas significant correlation in women was only between adiposity and plasma triglycerides. Systolic and diastolic blood pressure in men was strongly correlated with their plasma triglycerides, but not cholesterol, when the effect of age and adiposity was removed. In women however only a weak correlation was observed between plasma triglycerides and systolic blood pressure. The significance of the findings is discussed.

Adult↗

A method of intrarenal blood flow measurement using xenon-133 in the intact rat.

A method is described for measuring distribution of intrarenal blood flow in anesthetized rats by a xenon-133 washout technique that avoids the trauma of opening the abdominal cavity and manipulating the kidney. Precise delivery of the tracer to the kidney and fine collimation of the radiation reduces the amount of tracer required. Washout curve analysis is achieved by a multifit computer program that accepts only count rates and time as input data.

Animals↗

Long-term measurement of total exchangable sodium in one- and two-kidney Golblatt rats.

Total exchangeable sodium (Nae) was measured by wholebody counting of 22Na in 1- and 2-kidney Goldblatt rats before, and for 12 weeks after, renal artery clipping. In 1-kidney Goldblatt rats, Nae relative to body weight increased immediately after the clipping procedure and then fell though not to normal levels; from the 10th to the 12th week it again rose rapidly, probably secondary to vascular damage. In 2-kidney Goldblatt rats, Nae relative to body weight increased immediately after the clipping procedure but by the 5th day it was back to normal and remained normal thereafter. Consideration of the values for absolute Nae (i.e. expressed in mmol per rat) casts some doubt on the reality of the sodium 'retention', except in the 1-kidney Goldblatt rats in the later stages of their hypertension. Immediately after surgery temporary loss of weight (presumably mainly affecting fat stores and muscle) probably accounts for much of the rise in Nae relative to body weight.

Animals↗

Hypertension.

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Adult↗

Comparison of tienilic acid with cyclopenthiazide in hyperuricaemic hypertensive patients.

Tienilic acid, a diuretic with uricosuric properties, was compared with cyclopenthiazide, in an open, random-order, within-patient crossover study (3 months on each drug) in 36 hyperuricaemic hypertensive patients. All were on an established dose of cyclopenthiazide; most were also on a beta-blocker which they continued to take in their usual dose. A mean dose of 210 mg of tienilic acid gave the same antihypertensive and diuretic effect as a mean dose of 0.41 mg of cyclopenthiazide. Serum uric acid was very much lower when patients were on tienilic acid (0.29 mmol/l) than on cyclopenthiazide (0.50 mmol/l). Apart from slightly higher serum-chloride and serum-urea during the period on tienilic acid, no major differences in serum-electrolytes, renal-function tests, glucose tolerance, and fasting lipids were observed. Audiometric tests showed that tienilic acid was not ototoxic. S.G.O.T. and S.G.P.T. rose to pathological values in 3 women when they were on tienilic acid, to a lesser extent, in 2 men when they were on cyclopenthiazide. There is no definite evidence that the changes in the transaminases were related to tienilic acid. Some postural hypotension or slight fluid retention occurred during the initial, dose-finding period, and 3 patients had mild indigestion but no patient had to discontinue the trial because of side-effects.

Blood Pressure↗

The Milton Survey. 2. Blood pressure and heart rate.

Blood pressure and heart rate were measured in 1,206 adult inhabitants of Milton, about 82 percent of the adult population. Mean blood pressure for the various 10 year age groups was very similar to that found in other comparable societies. There was quite a high prevalence of blood pressure levels of 160/95 mmHg or over, especially in the older age groups. Blood pressure was lower in young women than in young men but rose more steeply with age in women than in men, so that in old age it was higher in women than men even though antihypertensive treatment was much more common in the women. Heart rate was higher in women than in men; in both sexes, heart rate correlated strongly with blood pressure. Quetelet's index (weight/height) also correlated strongly with blood pressure; this suggests once again that the amount of hypertension in the community might be reduced if body weight could be kept at desirable levels.

Adolescent↗