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Biomedical subjects

W J Kalk

Publications and source records attributed to W J Kalk.

At least 19 recordsLinked to original sources
PubMed1992

Fat, protein and carbohydrate content of diets of white insulin-dependent diabetic adolescents and young adults.

Dietary habits and serum cholesterol levels were surveyed in 39 young insulin-dependent diabetic subjects (mean age (+/- SD) 17.7 +/- 4.0 years, 21 females, 18 males). All had received the routine dietary advice that total carbohydrate, fat and protein consumption should constitute more than 45-50%, less than 30-35% and less than 20% respectively of total energy intake. Of the subjects 27 (69%) consumed more fat and 21 (54%) less carbohydrate than recommended. Fat consumption correlated positively with total energy (r = 0.747; P less than 0.00001) and negatively with carbohydrate intake (r = -0.757; P less than 0.00001), suggesting that restrictions placed on carbohydrate energy sources were offset by greater fat ingestion. Serum cholesterol exceeded the recommended ideal of 5.2 mmol/l in over half the subjects, and correlated positively with body mass index. Dietary advice to insulin-dependent diabetic patients must emphasise the freer consumption of unrefined carbohydrates, so as to reduce fat intake.

Adolescent↗
PubMed1992

The relationship between the development and progression of microalbuminuria and arterial blood pressure in type 1 (insulin-dependent) diabetes mellitus.

OBJECTIVE: to investigate the association between urinary albumin excretion and arterial blood pressure in type 1 (insulin-dependent) diabetes. RESEARCH DESIGN AND METHODS: urinary albumin excretion and blood pressures were followed prospectively for a mean period of 26 months (range 18-29 months) in 46 young type 1 (insulin-dependent) diabetic subjects without overt nephropathy. Supine blood pressures (BP) were measured by a single observer using a random zero sphygmomanometer. Albumin excretion was assessed at baseline by a timed clinic excretion rate (AER; microalbuminuria = AER greater than 33 micrograms/min), and at follow-up in at least two urine specimens by the albumin/creatinine (A/Cr) ratio (micro-albuminuria = A/Cr greater than 3.7 mg/mmol). RESULTS: 39 subjects initially had normal AERs. Seven had developed microalbuminuria at follow-up: their mean BP rose from 114 +/- 13/62 +/- 13 to 119 +/- 7/77 +/- 5 mmHg (for diastolic BP, P less than 0.05), while there was no change in the mean BP in the remaining 32 patients. A rise in diastolic BP of greater than 10 mmHg occurred in five of the seven subjects who developed microalbuminuria, and in only seven of 32 who did not (P = 0.02). In the seven patients in whom microalbuminuria persisted (n = 3) or progressed to overt proteinuria (n = 4), BP increased from 123 +/- 12/70 +/- 14 to 139 +/- 12/88 +/- 10 mmHg (P less than 0.02 for both). CONCLUSIONS: this study has shown that BP is normal before the onset of microalbuminuria, and that a rise in diastolic BP accompanies the development or progression of microalbuminuria. The rate of rise in BP may be more important than the absolute level in defining 'hypertension' in young diabetic patients with microalbuminuria.

Adult↗
PubMed1992

Influence of dietary protein on glomerular filtration and urinary albumin excretion in insulin-dependent diabetes.

We investigated the effects of dietary constituents on glomerular filtration (GFR) and albumin excretion rates (AERs) in a cross-sectional study in 39 young subjects with insulin-dependent diabetes. Dietary protein intake correlated significantly in patients with GFRs less than 150 mL/min per 1.73 m2 (r = 0.53, n = 23, P = 0.009), but not with AER. GFR also correlated with mean blood glucose at a concentration less than 12.0 mmol/L (r = 0.61, P = 0.0035). Protein and fat intakes were similar in patients with and without microalbuminuria (AER greater than 20 mg/L) but long-term glycemic control was worse in the former [HbA1 12.4 +/- 2.9% (mean +/- SD) and 10.6 +/- 2.1%, respectively, P = 0.043]. In seven patients, short-term reduction of dietary protein from 2.0 to 1.0 to 0.5 g.kg-1.d-1 produced a progressive fall in GFR by 11.6 +/- 6.0 and 9.6 +/- 5.9 mL/min, respectively (P less than 0.05), but did not consistently affect AER. We conclude that both dietary protein and glycemic control influence GFR but neither alone appears to explain glomerular hyperfiltration. Microalbuminuria was associated with poor glycemic control but not with dietary fat or protein consumption.

Adolescent↗
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↗
PubMed1979

Comparison of 99mTc and 131I scans in thyroid function studies.

Thyroid function was studied in 170 patients, using technetium-99m (99Tc) and oral radio-iodine (131I); 110 patients had normal thyroid function, and 60 had hyperthyroidism. The 20-minute 99mTc uptake gave an accurate assessment of thyroid function in 95% of patients, and the 24-hour 131I uptake was accurate in 92%. One hundred 99mTc and 131I scintiscans were compared by 3 observers. Scans obtained with each isotope were of comparable quality, and in only 1 patient were both scans of poor quality. 99mTc is as good as 131I for assessing thyroid function and morphology, but has several advantages over 131I.

Evaluation Studies as Topic↗
PubMed1979

Insulin secretion and pancreatic exocrine function in patients with chronic pancreatitis.

The relationship between insulin responses to oral glucose and pancreatic exocrine function were examined in 15 patients with chronic pancreatitis. Good correlations were found between the insulin responses and exocrine pancreatic function measured as the concentrations of pancreatic enzymes in duodenal juice after intravenous cholecystokinin-pancreazymin (CCK-PZ). There appears to be a roughly parallel loss of endocrine and exocrine function in the course of chronic pancreatitis.

Administration, Oral↗
PubMed1978

Post-thyroidectomy thyrotoxicosis.

94 patients with postoperative recurrent hyperthyroidism were evaluated for duration of remission, goitre size, and response to radio-iodine (131I). 6 patients required 131I therapy within twelve months of operation--5 had large remnants because of inadequate surgery. 57% of patients relapsed within 5 years, but 16% relapsed after 20 years and 8% after more than 30 years. Estimated goitre weights ranged from 4 g to 65 g, and goitre size was unrelated to the duration of remission. All patients were treated with 131I. 23% of the patients became hypothyroid in the first postoperative year and 10% in the second year. The results indicate that postoperative thyrotoxicosis can recur decades after operation. Operation seems to sensitise the thyroid to the early effects of radiation by 131I.

Adult↗
PubMed1977

An evaluation of the effects of some sulphonylureas on platelet function.

The effect of the sulphonylureas gliclazide (S 852) and glibenese on platelet function, blood lipid levels and the control of diabetes, was prospectively evaluated in 12 maturity-onset diabetic subjects by means of a double-blind crossover study. Including the pretrial period, platelet aggregation in response to collagen was uniformly lower than in matched normal controls, but neither drug produced any additional effect on platelet function. Control of blood glucose levels was no better than with comparable agents, and no measurable changes occurred in blood lipid levels. The drugs had no significant side-effects and were well tolerated. It is concluded that neither agent offers special advantages over other sulphonylureas, particularly in regard to platelet function.

Blood Glucose↗