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Biomedical subjects

R Wilkinson

Publications and source records attributed to R Wilkinson.

At least 325 records · Page 18Linked to original sources
PubMed1985

The effect of propranolol on circulating thyroid hormone measurements in thyrotoxic and euthyroid subjects.

Circulating concentrations of total and free thyroid hormones and thyroid hormone binding proteins were measured in thyrotoxic and euthyroid subjects treated with propranolol. In the thyrotoxic group, total triiodothyronine (T3) concentration fell after propranolol therapy, suggesting an effect of the drug on the peripheral conversion of thyroxine (T4) to T3. In euthyroid subjects, a rise in circulating concentrations of free T4 and reverse T3 (rT3) was observed, while only a small decrease in free T3 was evident. Thyroxine binding globulin (TBG) concentration fell during propranolol treatment while thyroxine binding prealbumin (TBPA) concentration rose. The changes observed in the euthyroid state are consistent with inhibition of peripheral deiodination of T4 and rT3; an additional effect of propranolol on binding protein metabolism was evident.

Humans↗
PubMed1985

Renal function and blood pressure after donor nephrectomy.

Pre- and post-nephrectomy renal function and blood pressure were compared in 75 subjects who had donated a kidney for transplantation during the past 20 years. The function of the remaining kidney was not adversely affected by prolonged compensatory hyperfiltration. However, an increased prevalence of hypertension was found in 'long-term' kidney donors.

Blood Pressure↗
PubMed1985

The renin-angiotensin-aldosterone system in decompensated cirrhosis: its activity in relation to sodium balance.

Plasma renin activity (PRA), plasma renin concentration (PRC), plasma angiotensin II concentration (AII), plasma and urinary aldosterone (PA, UA) and urinary sodium excretion (UNaV) were measured in 51 normal controls, 16 patients with decompensated cirrhosis (i.e. ascites and/or oedema present) in sodium equilibrium (Group 1) and 13 patients with decompensated cirrhosis in a phase of active sodium retention (Group 2). In Group 1 the mean supine and erect values, although lower, were not significantly different from controls. In Group 2 the mean values were significantly elevated, but several individual values were within the normal range; there were significant direct relationships between plasma renin activity and plasma renin concentration (r = 0.85, p less than 0.001 erect), plasma renin concentration and plasma angiotensin II concentration (r = 0.86, p less than 0.001 erect), and plasma angiotensin II concentration and plasma aldosterone (r = 0.70, p less than 0.01 erect). In Group 2 there was an inverse correlation between urinary sodium excretion and both urinary aldosterone (r = -0.50) and erect plasma aldosterone (r = -0.36) but, perhaps because of the narrow range of sodium excretion rates, significance was not reached. The normal values in Group 1 indicate that hyperaldosteronism is not essential for the maintenance of established ascites, but do not exclude a role for aldosterone in the control of sodium excretion if it is accepted that renal tubular sensitivity to aldosterone is increased in these patients. In Group 2, the raised mean plasma and urinary aldosterone levels and the trend towards an inverse relationship with urinary sodium excretion suggests a role for aldosterone in the active retention of sodium. It appears that stimulation of the renin-angiotensin system is the major factor in the elevation of plasma aldosterone; there was no relationship between plasma aldosterone and either plasma sodium or potassium levels. The mechanism of renin hypersecretion is unclear but this may represent part of a sympathetically mediated response in order to maintain blood pressure. The close relationship between plasma renin activity and plasma renin concentration indicates that the former is a valid measure of circulating renin levels in cirrhosis, despite low renin-substrate levels.

Aldosterone↗
PubMed1985

Renal osteodystrophy and metastatic calcification in long-term continuous ambulatory peritoneal dialysis.

The biochemical data and drug histories related to bone disease were extracted from the case records of 47 patients who had been treated by continuous ambulatory peritoneal dialysis (CAPD) for more than two years. These data were reviewed in conjunction with the skeletal surveys done over the same period in all patients, with particular reference to secondary hyperparathyroidism, osteomalacia and non-visceral metastatic calcification. Paired bone biopsies were available in 20 of these patients and the histology was quantitated. In the majority of our patients secondary hyperparathyroidism was controlled or improved on CAPD. Osteomalacia also improved in two of the three patients in whom it was initially present and did not develop in any patient whilst on CAPD. We did, however, note a high incidence of non-visceral metastatic calcification. Small vessel calcification developed in 19.6 per cent of patients, large vessel calcification developed in 23.9 per cent and soft tissue calcification developed in 21.7 per cent of patients. We conclude that CAPD, as a form of treatment for end-stage renal disease, satisfactorily controls the osteodystrophy associated with renal failure in the majority of patients. The significance of the high incidence of non-visceral metastatic calcification remains to be established.

Adult↗
PubMed1985

Evaluation of the intact hormone assay in the study of parathyroid autograft function.

Parathyroid autograft function was studied using radioimmunoassay measuring intact parathormone (iPTH) and C-terminal PTH (C-PTH). Blood samples were taken from graft and non-graft arms pre- and post-dialysis. The intact assay showed an appreciably greater differential gradient pre- and post-dialysis than the C-terminal assay. We conclude that particularly in patients with chronic renal failure the intact assay is of greater value in monitoring graft function than the commonly used C-terminal assay. It may also be of value in distinguishing between graft overactivity and ectopic cervical parathyroid tissue in cases of recurrent hyperparathyroidism following apparently total parathyroidectomy and autotransplantation.

Humans↗
PubMed1985

Dual lumen subclavian catheters for haemodialysis.

The dual lumen catheter has recently been developed as a subclavian vascular access device for haemodialysis. This paper describes our preliminary experience with two currently available catheters of this design: the Shiley Dual Lumen Catheter, and the Quinton-Mahurkar Dual Lumen Catheter. The performance of both catheters, characterised by high blood flow rate capabilities, low venous resistances and minimal recirculation, is superior to that of other types of subclavian haemodialysis cannula.

Aged↗
PubMed1985

Renovascular hypertension: ten years' experience in a regional centre.

In a unit serving a population of three million, 60 hypertensive patients with renovascular disease were identified over a 10-year period. The presence of renovascular disease was usually suggested by intravenous urography (IVU), although this was falsely negative in 21 per cent of cases; isotope renography (IR) was normal in a similar proportion of patients (25 per cent). Eight patients were treated medically and 52 underwent surgical procedures; nephrectomy in 32, autotransplantation in 10, by pass graft in six and percutaneous transluminal angioplasty in four. Twenty-three per cent of patients were cured, 37 per cent improved and 40 per cent unchanged one year after surgery, but the response could not be accurately predicted. Clinical features were of some value in that those patients most likely to benefit from surgery were younger, had less severe hypertension of shorter duration, smoked less, had less severe retinopathy and less cardiomegaly. There was also a trend for those with better renal function and less electrocardiographic evidence of left ventricular hypertrophy to benefit from surgery. The IVU and IR did not predict response to surgery but arteriographic appearances of fibromuscular dysplasia indicated there should be a favourable response. The renal vein renin ratio, basal or stimulated, was of no prognostic value since approximately two-thirds of patients with ratios above or below the threshold value had some benefit from surgery. We conclude that the surgical treatment of renovascular hypertension is worthwhile but the number of patients suitable for surgery is small. Clinical features and the results of simple investigations provided the best guide to surgical outcome in our patients.

Adult↗
PubMed1984

Priority reading.

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Attitude of Health Personnel↗
PubMed1984

Factors affecting development of peritonitis in continuous ambulatory peritoneal dialysis.

A questionnaire based survey in patients receiving continuous ambulatory peritoneal dialysis showed that there was an increased incidence of upper respiratory tract symptoms (suggestive of viral illness) in the 14 days before the development of peritonitis. No other factors were identified that might distinguish patients who develop peritonitis. The possibility that viral infections predispose to peritonitis by altering host defence mechanisms in patients receiving this form of renal replacement therapy warrants further study.

Humans↗
PubMed1984

Hepatitis B as a sexually transmitted disease in a black South African population.

This study compares the hepatitis B surface antigen (HBsAg) and anti-hepatitis B antibody (anti-HBs) statuses of 1 032 Black patients with syphilis (338 male and 694 female) with those of 3 021 (758 male and 2 263 female--anti-HBs) and 8 310 (3 257 male and 5 053 female--HBsAg) unpaid blood donors with a negative syphilis test result who were of similar ethnic origin. The results for the groups of males showed no statistically significant differences even when the HBsAg and anti-HBs results were summed to provide an index of previous hepatitis B infection. In contrast, the group of females with syphilis had a significantly higher incidence of both markers compared with the blood donors (HBsAg in 7,20% v. 3,46% of controls and anti-HBs in 50,14% v. 41,05%). These findings would seem to support the view that hepatitis B viral infection may be more easily transmitted from males to females during sexual contact than vice versa.

Female↗
PubMed1984

Surgical aspects of continuous ambulatory peritoneal dialysis--3 years experience.

Since January 1979, 122 patients (mean age 38.5 years, range 5-72 years) with chronic renal failure have been treated with continuous ambulatory peritoneal dialysis (CAPD). Peritoneal access was achieved by inserting silicone rubber Tenckhoff peritoneal dialysis catheters (Quinton, Seattle, Washington) by an open (76 per cent) or closed technique. Actuarial analysis showed a patient survival of 98 and 94 per cent and a success rate of 88 and 64 per cent at 1 and 2 years, respectively. Currently, 74 patients are using CAPD and 8 have been treated for 30-36 months. Thirty-five patients (29 per cent) required two or more peritoneal catheters and 69 per cent of these patients are still on CAPD. Catheter-related peritonitis was the most frequent complication (233 separate episodes in 94 patients) and necessitated catheter removal in 16 per cent of episodes, although 37 per cent of patients from whom catheters were removed because of peritonitis later resumed CAPD. Extravasation of dialysate from the peritoneal cavity (31 episodes) and catheter obstruction (31 episodes) required surgical replacement of catheters in 8 and 23 cases, respectively. Twenty patients (16 per cent) developed 24 abdominal hernias, only one of which caused failure of CAPD. Infective and mechanical complications of CAPD frequently require surgical intervention but only occasionally result in failure of the technique, and even multiple catheter replacements are compatible with successful long term CAPD.

Abdomen↗
PubMed1984

A comparison of propranolol and nadolol pharmacokinetics and clinical effects in thyrotoxicosis.

For a comparison of propranolol and nadolol pharmacokinetics and clinical effects, 20 newly diagnosed patients with thyrotoxicosis were randomly selected to receive as sole therapy, either propranolol, 40 mg every 6 hours for 14 days, or nadolol, 80 mg each morning for 14 days. The study was repeated when the patients were in the euthyroid state. There was a similar and highly significant degree of beta blockade and amelioration of symptoms of thyrotoxicosis at the end of the dosage interval (trough), i.e., 24 hours after nadolol or 6 to 8 hours after propranolol. Trough and peak serum levels of propranolol were significantly lower when the patients were in a thyrotoxic state than when they were in a euthyroid state, whereas the pharmacokinetics of nadolol were not appreciably altered by thyrotoxicosis. In thyrotoxicosis, trough levels of propranolol and nadolol were significantly inversely correlated with derived creatinine clearance values. In the symptomatic treatment of thyrotoxicosis, nadolol, a once-daily nonmetabolized beta blocker, has certain advantages compared with propranolol. It is preferred by patients, is more convenient, and probably aids compliance.

Adolescent↗
PubMed1984

Atenolol pharmacokinetics in patients on continuous ambulatory peritoneal dialysis.

The elimination of atenolol (20 mg i.v.) has been studied in seven patients with renal failure on continuous ambulatory peritoneal dialysis (CAPD). Although atenolol was eliminated in the peritoneal fluid, the amount recovered in 24 h was relatively low (1.2 +/- 0.15 mg). The calculated urinary (n = 4) and peritoneal (n = 7) clearance was 0.289 +/- 0.058 l/h and 0.152 +/- 0.018 l/h respectively. This was considerably less than calculated total body clearance (1.21 +/- 0.086 l/h). The kinetics of atenolol in CAPD are worthy of further study.

Adult↗
PubMed1984

Measurement of free thyroxine and free triiodothyronine in thyrotoxicosis and hypothyroidism.

Free T4 and free T3 concentrations in thyrotoxic and hypothyroid patients at presentation differentiated those with thyroid disease from euthyroid control subjects and were closely correlated with T4/TBG ratio. A further group of thyrotoxic patients was followed serially during treatment with carbimazole. Measurements of free T4 and free T3 against closely reflected thyroid status with changes in the hormone measurements being paralleled by changes in T4/TBG ratio.

Carbimazole↗