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Biomedical subjects

W J Kalk

Publications and source records attributed to W J Kalk.

At least 37 records · Page 2Linked to original sources
PubMed1991

Hypertension, proteinuria and azotaemia in diabetes.

The prevalence of hypertension was evaluated in 479 white subjects with diabetes, according to the type of diabetes and the presence of persistent proteinuria as a marker for diabetic nephropathy. Hypertension was uncommon in 178 insulin dependent diabetic subjects without proteinuria (5%) (mean age 25.0 +/- 12.5 years), but occurred in 23% of 58 patients with proteinuria (mean age 28.9 +/- 14.1 years) and in 90% with azotaemia (P less than 0.00001). Among patients with non-insulin-dependent diabetes hypertension was found in 25% of 170 without renal disease (mean age 48.0 +/- 10.3 years) and in 53% of 53 (mean age 51.4 +/- 13.0 years) with proteinuria (P = 0.0002). We conclude that the prevalence of hypertension among subjects with diabetes depends on the type of diabetes, age, and the presence and severity of diabetic renal involvement.

Adolescent↗
PubMed1991

Hospital management of voluntary total fasting among political prisoners.

In 1989 20 political detainees, held without trial for up to 32 months, were admitted, on hunger strike, to the Johannesburg Hospital, South Africa. Most were held under the regulations of the State of Emergency (since revoked) and 5 were held incommunicado under section 29 of the Internal Security Act (still in force). Guidelines for ethical management were based on the Declaration of Tokyo, which included the understanding that such detentions constituted mental torture. Conditions of detention in hospital were complicated by police interference in medical and nursing care, and by the chaining of some prisoners to their beds. Doctors are in a unique position to protest against inhuman treatment of prisoners, and should use this authority.

Adolescent↗
PubMed1991

Hypoglycemia in hepatocellular carcinoma: failure of short-term growth hormone administration to reduce enhanced glucose requirements.

The mechanism of tumor-associated hypoglycemia was investigated in 10 (six hypoglycemic and four normoglycemic) southern African blacks with hepatocellular carcinoma. The mean basal blood glucose concentration was significantly lower (2.4 +/- 0.1 v 3.6 +/- 0.2 mmol/L; P less than .01) and steady-state exogenous glucose requirements were increased fourfold (3.6 +/- 0.6 v 0.97 +/- 0.2 mg/kg/min; P less than .01) in the hypoglycemic compared with the normoglycemic patients. Plasma insulin and C-peptide levels were suppressed to the lower limit of sensitivity of each of the assays in both groups of patients. The concentrations of insulin-like growth factors (IGF) I and II were lower (19 +/- 1.6 v 25 +/- 4.6 insulin-like growth factors (IGF) I and II were lower (19 +/- 1.6 v 25 +/- 4.6 ng/L) and higher (230 +/- 42 v 173 +/- 40 ng/L), respectively, in the hypoglycemic patients, although the differences were not statistically significant. Of the counterregulatory hormones measured, only the growth hormone (GH) concentration was significantly lower in the hypoglycemic patients (0.9 +/- 0.2 v 18.6 +/- 5.6 micrograms/L; P less than .01). Correction of the plasma GH level into the high-normal physiological range in two hypoglycemic patients failed to reduce steady-state exogenous glucose requirements. However, the glucose requirements were reduced from 2.6 to 1.1 mg/kg/min in the same two patients when "acromegalic" plasma concentrations of GH were achieved. We conclude that steady-state glucose requirements are increased in black patients with hypoglycemia complicating hepatocellular carcinoma, and that short-term correction of the associated hyposomatotropism fails to reduce the enhanced requirements.

Blood Glucose↗
PubMed1990

The acute effects of glucosidase inhibition on post-meal glucose increments in insulin-dependent diabetics.

The effects of glucosidase inhibition on postprandial glucose tolerance was studied in 11 insulin-dependent diabetics. In comparison with placebo, 50 mg miglitol was able to lower the incremental glucose response significantly at 30 minutes and 60 minutes when insulin was injected: (i) 30 minutes before the meal (2,3 +/- 0,5 mmol/l v. 0,37 +/- 0,2 mmol/l; P less than 0,001; and 5,0 +/- 0,7 mmol/l v. 1,1 +/- 0,8 mmol/l; P less than 0,001); and (ii) immediately before the meal (2,3 +/- 0,5 mmol/l v. 2,2 +/- 0,9 mmol/l; P less than 0,001) respectively. The incremental glucose area under the curve when insulin was injected 30 minutes before breakfast was also significantly reduced on miglitol in comparison with placebo (0,67 +/- 0,15 mmol/l v. 0,16 +/- 0,14 mmol/l; P less than 0,01). The effect of miglitol was more evident when insulin was injected 30 minutes before rather than immediately before the meal. No significant adverse effects were encountered. It is concluded that: (i) miglitol safely reduces the early post-meal glucose increments in insulin-dependent diabetics; and (ii) its effect enhances the hypoglycaemic response of an appropriately timed injection of insulin.

1-Deoxynojirimycin↗
PubMed1990

Prior long term glycaemic control and insulin therapy in insulin-dependent diabetic adolescents with microalbuminuria.

Adolescence seems to be a period of increased risk for the initiation of diabetic renal disease in insulin-dependent diabetic children. Poor glycaemic control is a risk factor for diabetic nephropathy. We have therefore evaluated prior long-term glycaemic control in 23 diabetic adolescents with microalbuminuria (albumin excretion rate (AER) 20-200 micrograms/min, median 39.0 micrograms/min) and in 23 matched diabetic controls with AER less than 20 micrograms/min (median 9.3 micrograms/min). Glycaemic control was assessed by mean HbA1 and clinic blood glucose levels over a period ranging from 12 to 84 months (median 48 months). Mean HbA1 was 13.6 +/- 2.0% in the microalbuminuric subjects, compared to 11.5 +/- 2.2% in the controls (P less than 0.002); mean blood glucose levels were 13.5 +/- 3.0 and 11.4 +/- 3.0 mmol/l, respectively (P less than 0.02). There appeared to be a 'threshold effect' (mean HbA1 greater than 12.0%), above which the development of microalbuminuria was more likely. More patients with microalbuminuria than controls had been treated with a single rather than twice-daily insulin injections (P less than 0.001), and glycaemic control was significantly worse in patients treated with one injection. We conclude that poor long term glycaemic control is a risk factor for microalbuminuria, and that improving control during childhood is likely to reduce the prevalence of later microalbuminuria. Two insulin injections, of combined intermediate and short-acting preparations, are more likely to provide better control than a single daily insulin dose.

Adolescent↗
PubMed1990

The prevalence of micro-albuminuria and glomerular hyperfiltration in young patients with IDDM.

We have assessed the prevalence of two risk factors for diabetic nephropathy, i.e., micro-albuminuria and a raised glomerular filtration rate (GFR), in 127 insulin-dependent diabetic patients aged 13-36 years. Micro-albuminuria (albumin excretion rate (AER) 20-200 micrograms/min) was found in 46 subjects (36%) and GFR was elevated (greater than 135 ml/min/1.73 m2) in 43 (34%). The prevalence of supranormal GFR declined and that of micro-albuminuria rose progressively with the increasing duration of diabetes. While age and sex distribution were similar in subjects with and without raised AER, duration of diabetes was significantly longer, blood pressure (BP) was significantly greater and age of onset was lower in the micro-albuminuria group. Blood pressure was significantly elevated only in the patients with AER of 70-200 micrograms/min; there was a linear trend for BP to rise as AER increased. Stepwise logistic regression analysis indicated that duration of diabetes (P less than 0.0001), age of onset of diabetes (P less than 0.005) and current glycaemic control (HbA1) (P less than 0.01) were risk factors for micro-albuminuria. The association with a rising blood pressure appears to be secondary to the renal involvement. In this cross-sectional study an association of micro-albuminuria with a raised GFR could not be demonstrated.

Adult↗
PubMed1989

Incidence and causes of hyperthyroidism in blacks.

Between 1974 and 1984 688 black patients with hyperthyroidism were seen at one clinic. Graves' disease made up 88% of cases, with a female: male ratio of 7,9:1. The average annual incidence for females was 8,75/100,000 and for males 0,70/100,000. There appeared to be a progressive increase in incidence (60%) over the period. A bimodal age distribution was observed with peaks at 35-54 years (almost exclusively Graves' disease) and in those older than 64 years (Graves' disease 66%, nodular goitres 34%). Although hyperthyroidism seems rare in rural Africa, 59% of the patients surveyed (N = 88) had been born in such an area and were urban migrants. Moreover, some ethnic groups were disproportionately represented. In one of these (Tswana-speaking), 81% had migrated from rural areas of endemic goitre, usually as adults. It is concluded that hyperthyroidism remains relatively uncommon in the black population in this region. The incidence of Graves' disease, but not of toxic nodular goitre, appears to be increasing rapidly. The process of urbanisation, including possible increases in dietary iodide, may contribute to this apparent increase in Graves' disease in urban areas.

Adolescent↗
PubMed1989

Clinical and biochemical responses to nadolol and clonidine in hyperthyroidism.

Some features of hyperthyroidism mimic sympathetic nervous system overactivity. We have compared the clinical (scored on the Wayne Therapeutic Index), hemodynamic (blood pressure and heart rate) and biochemical (plasma epinephrine, norepinephrine, glucose, free fatty acids, insulin, growth hormone and free thyroxine index) effects of clonidine (alpha 2-agonist, which reduces plasma catecholamine levels) with those of nadolol (non-selective beta adrenergic receptor antagonist) in ten female hyperthyroid patients. Each patient received nadolol for 1 week followed by clonidine for 1 week in a single-blind manner. All measurements were made before treatment and then repeated at the end of the nadolol and clonidine treatment periods. Thyroid function remained unaltered during the study. Both agents caused significant clinical improvement--the mean Wayne Index score was 18 pretreatment, 2 on nadolol and 6 on clonidine (P less than .003 for each). Heart rate was reduced by both drugs, but blood pressure was unchanged. Side effects occurred in eight out of ten patients while on clonidine. Nadolol increased plasma concentrations of epinephrine from 47 +/- 18 pg/mL to 87 +/- 24 pg/mL, and norepinephrine from 241 +/- 154 pg/mL to 338 +/- 224 pg/mL (P less than .001 for each). In contrast, clonidine depressed norepinephrine levels from 241 +/- 154 pg/mL to 110 +/- 49 pg/mL (P less than .001) without lowering plasma epinephrine significantly. Plasma free fatty acids tended to fall on both agents compared to pretreatment levels. The blood glucose, insulin and growth hormone concentrations were unaffected by either drug.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

Drug therapy for Graves' disease in blacks--very low rates of remission.

The rates of remission after a course of antithyroid drugs in 71 black and 45 white patients with Graves' disease were compared. One year after stopping therapy 27% of blacks and 47% of whites were in remission (P less than 0.01); at 2 years the proportions were 7% and 27% respectively (P less than 0.05). Small size of goitre only was a weak predictor of remission; duration of therapy did not influence the outcome. HLA A2 and B17 may be less frequent in black patients who remain in remission (P = 0.048 and 0.067 respectively). The data suggest that it is not worth while undertaking a trial of medical therapy in unselected black patients with Graves' disease.

Adult↗
PubMed1987

Hypercalcaemia in the Johannesburg Hospital. Differential diagnosis and physician awareness of primary hyperparathyroidism.

A 1-year retrospective study of all serum profiles of patients with hypercalcaemia analysed at the Johannesburg Hospital was carried out to ascertain the causes of hypercalcaemia and physician awareness of primary hyperparathyroidism. Hypercalcaemia was found in 560 subjects (2.9% of 19,200), but in 147 of these (26%) this was not confirmed by repeat estimations. Malignant tumours were the commonest cause (38.4%) and accounted for the most severe hypercalcaemia (mean serum calcium 2.93 mmol/l). Renal disease resulted in significant hypercalcaemia, at times requiring parathyroidectomy. Drug-associated hypercalcaemia was usually mild and reversible on drug withdrawal. Although primary hyperparathyroidism occurred in 21.3% of cases, overall physician awareness of the disease was poor (39%). 'Incidental' profile hypercalcaemia (P less than 0.005) and hypertension (P less than 0.005) were frequent presenting features in this study. Renal disease (P less than 0.001) occurred infrequently.

Calcium↗
PubMed1987

Plasma C-peptide and insulin responses to intravenous glucagon stimulation in idiopathic haemochromatosis.

Beta-cell reserve was investigated in 15 patients with proven idiopathic haemochromatosis (IHC) (7 normoglycaemic haemochromatotic patients, 4 non-insulin-requiring diabetics and 4 insulin-requiring diabetics) by measuring the response of plasma C-peptide, insulin and glucose to a 2 mg intravenous bolus of glucagon, and compared with that in 5 lean normal subjects. The corresponding C-peptide/insulin molar ratios were also calculated. Despite the significant fasting hyperglycaemia in the insulin-requiring haemochromatotic diabetics, mean fasting C-peptide concentrations were similar in all four groups. However, after glucagon stimulation the C-peptide response was significantly reduced in the insulin-requiring group over the whole period of observation. A trend in insulin response to glucagon was noted, with the highest values in the non-diabetic haemochromatotic patients, followed by the controls and then by the non-insulin-requiring diabetics, although there were no significant differences. In contrast, C-peptide/insulin molar ratios after glucagon were significantly reduced in the normoglycaemic IHC group. These results suggest the presence of at least two abnormalities of insulin metabolism in IHC--a progressive reduction in beta-cell function and a diminished rate of removal of insulin by the liver.

Adult↗
PubMed1987

The effect of kallikrein on spermatozoal ATP and other semen parameters.

Kallikrein promotes the release of kinins, which have been shown in in vitro studies to improve motility, viability and metabolism in human spermatozoa. The effects of kallikrein therapy on 25 males attending an infertility clinic was assessed, regarding endogenous spermatozoal ATP content, as well as other semen parameters. Thirteen of the 25 patients showed an improvement in either count, morphology, motility, viability, or a combination of these, after 3 months Kallikrein therapy. ATP levels in responders dropped by 58.8% (p less than 0.001). In nonresponders ATP levels did not change significantly. This indicates that improvement in spermatozoal parameters corresponds with increased ATP consumption, following Kallikrein therapy.

Adenosine Triphosphate↗
PubMed1986

Primary hyperparathyroidism. A study of 100 patients in Johannesburg.

This study comprised 100 white patients with primary hyperparathyroidism treated between 1975 and 1984. Of these, 75 attended Johannesburg Hospital and 25 were managed by private practitioners. The mean age was 56.4 +/- 1.4 years at the time of diagnosis. There were almost twice as many women as men. In patients attending Johannesburg Hospital there was a progressive increase in the detection rate after 1979, which corresponded with the introduction of automated multichannel serum analysis. The commonest major complications were renal stones (54%), renal insufficiency (27%), a history of skeletal fractures (12%), radiographic evidence of osteopenia (38%) and peptic ulcers (20%). Bone disease was particularly common in postmenopausal women (64%). Other notable features were the frequency of weakness and fatigue (40%) and hypertension (45%). Coincidental thyroid abnormalities were frequent (18%). Ninety-three patients were treated surgically; 76 (81.7%) had a single adenoma. Our findings are compared with those of other large series. This study indicates the need for a greater awareness of this condition and earlier diagnosis to forestall the development of its harmful complications, and for the collection of additional information from a prospective study.

Adolescent↗