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Biomedical subjects

B F Clarke

Publications and source records attributed to B F Clarke.

At least 91 records · Page 5Linked to original sources
PubMed1983

A controlled trial of sorbinil, an aldose reductase inhibitor, in chronic painful diabetic neuropathy.

A double-blind, randomized, placebo-controlled cross-over trial of the aldose reductase inhibitor sorbinil was undertaken in 15 patients (age 35-68 yr) with chronic painful diabetic neuropathy. Treatment was evaluated by subjective pain responses, clinical examination, vibration perception threshold, motor and sensory nerve electrophysiology, and cardiovascular reflex tests of autonomic nerve function. Among the many measurements, only pain, tendon reflex scores, and sural sensory potential amplitude improved significantly during sorbinil administration, while scores of clinical sensory examination deteriorated. Four patients experienced an idiosyncratic reaction that rapidly recovered on discontinuing the drug. This study suggests that aldose reductase inhibitor treatment with suggests that aldose reductase inhibitor treatment with sorbinil may have an effect on symptomatic diabetic neuropathy in man.

Adult↗
PubMed1983

Abnormalities of ambulatory 24-hour heart rate in diabetes mellitus.

Twenty-one normal subjects and 64 diabetics with varying severity of autonomic damage underwent 24-h ambulatory EKG monitoring. No diabetics had the "sick sinus syndrome," and the frequency of arrhythmias was no higher than in the normal subjects. The diabetics had higher mean hourly heart rates, and with increasing autonomic damage there was reduction in diurnal heart rate variation. The mean waking and sleeping heart rates were higher in the diabetics. The maximum heart rates were not significantly different, but the minimum heart rates were significantly higher in the diabetics. These previously unrecognized abnormal 24-h heart rate patterns provide further evidence of damage to the heart rate-controlling mechanisms in diabetes mellitus.

Adult↗
PubMed1983

Nerve function and metabolic control in teenage diabetics.

Peripheral somatic and autonomic nerve function have been studied in 79 teenage (16-19 yr) diabetics and 20 age- and sex-matched normal controls. Almost three-quarters of the diabetics (72%) had abnormal peripheral somatic nerve function tests, and one-third (31%) had abnormal cardiac parasympathetic tests. Both motor and sensory peripheral somatic nerve abnormalities were related to poor prevailing glycemic control (HbA1) and duration of diabetes. Thus, the 27 patients with three or more (maximum six) peripheral nerve abnormalities had significantly higher HbA1 levels (P less than 0.001) and longer duration of diabetes (P less than 0.01) than the 22 with no abnormalities. Individual peripheral somatic nerve tests almost invariably correlated only with HbA1 (median motor, P less than 0.05; peroneal motor, P less than 0.001; sural sensory, P less than 0.001) or duration of diabetes (median sensory, P less than 0.001). Sensory potential amplitude, as well as conduction velocity, was frequently reduced, implying axonal involvement. These findings suggest that abnormal peripheral and autonomic nerve function are common in young insulin-dependent diabetics and that poor metabolic control is a major determinant of the damage. DIABETES 32:142-147, February 1983.

Adolescent↗
PubMed1983

Familial distribution of thyroid disease and diabetes: further evidence for aetiological heterogeneity of diabetes mellitus.

The prevalences of thyroid disease, insulin-dependent and non-insulin-dependent diabetes were compared in first degree relatives of diabetics with and without coexisting autoimmune thyroid disease. Thyroid disease was more common in siblings of diabetics with thyroid disease than in those of diabetics without thyroid disease. Insulin-dependent diabetes was more common in siblings of diabetics with a personal or family history of thyroid disease than in those of diabetics without such a history. The prevalence of non-insulin-dependent diabetes was unrelated to that of thyroid disease but was greater in siblings of non-insulin-dependent diabetics than in those of insulin-dependent diabetics. These findings add further support to the aetiological distinction between insulin-dependent and non-insulin-dependent diabetes and suggest that further heterogeneity exists within the population of insulin-dependent diabetics based on the presence of a personal or family history of thyroid disease.

Adult↗
PubMed1983

Non-insulin-treated ICA positive and negative diabetics are equally insulin resistant.

Insulin action was assessed in 5 cytoplasmic islet cell antibody (ICA) positive non-diabetics, 8 ICA positive (type I) non-insulin-treated diabetics, 7 ICA negative insulin-treated diabetics by measurement of steady state plasma glucose (SSPG) levels during a combined intravenous infusion of propranolol, adrenaline, glucose and insulin. SPPG values of ICA positive and negative non-diabetics were similar and their combined value (4.0 +/- 0.5 mmol/l) was significantly lower (p less than 0.01 and less than 0.01) than those (11.5 +/- 1.9 and 11.3 +/- 2.2 mmol/l) of ICA positive and negative diabetics, indicating that both groups of diabetics were similarly insulin resistant. Similar correlations were observed between SSPG and HbA1 levels when considering all ICA positive subjects (r = 0.89, p less than 0.001) and all ICA negative subjects (r = 0.73, p less than 0.01). Conventional insulin treatment (2.6 months) in 4 ICA positive diabetics improved insulin action in each case with a reduction in mean SSPG concentration from 14.0 +/- 2.3 to 8.5 +/- 3.4 mmol/l. Thus, ICA positive and negative diabetics, of equivalent degree of carbohydrate intolerance, are equally insulin resistant. Insulin treatment may improve, but appears not to normalise, insulin action in ICA positive (type I) diabetics.

Adult↗
PubMed1982

Glycosylated hemoglobin and its temporal relationship to plasma glucose in non-insulin dependent (type 2) diabetes mellitus.

Total glycosylated hemoglobin (HbAI) and random plasma glucose were measured at monthly intervals for 6 mo in 33 non-insulin dependent (type 2) diabetics. The mean HbAI and mean plasma glucose in individual patients over the 6 mo showed a close correlation (p less than 0.001). A significantly higher HbAI (p less than 0.001) for a given plasma glucose was seen in those patients receiving combined chlorpropamide and metformin therapy (n = 14) than in those receiving chlorpropamide alone (n = 19). For each patient correlation coefficients were calculated between plasma glucose and HbAI with time lags of 0.1 and 2 mo. The coefficients with no time lag showed a significant tendency to be positive (p less than 0.01) whereas those with time lags of 1 or 2 mo were not significant. A constant proportional variability of both HbAI and plasma glucose over time was demonstrated, the mean coefficient of variation for HbAI being 8.4 +/- 2.7% and for plasma glucose 22.3 +/- 9.7%. We conclude that HbAI provides an index of plasma glucose control, not during the preceding few months as was previously thought but, during the previous few weeks. In terms of variability from month to month a single HbAI determination was equivalent to approximately the mean of 3 single plasma glucose values.

Blood Glucose↗
PubMed1982

Preservation of the hypoxic drive to breathing in diabetic autonomic neuropathy.

1. Unexplained cardiorespiratory arrests have been reported in patients with diabetic autonomic neuropathy and these could be due to denervation of the carotid chemoreceptors. 2. We have studied the ventilatory response to transient hypoxia (Ve/Peto2) during exercise in 22 male diabetic patients, six with symptomatic and cardiovascular evidence to suggest diabetic autonomic neuropathy (DAN+) and 12 without these features (DAN-). 3. There was no difference in the ventilatory response to transient hypoxia between the different groups of diabetic patients (Ve/Peto2 in DAN+ patients = -0.9 +/- 0.2 litre min-1 kPa-1; Ve/Peto2 in DAN- patients = -1.2 +/- 0.6 litres min-1 kPa-1) even allowing for differences in the level of exercise achieved (CO2 production in DAN+ patients = 743 +/- 103 ml/min; CO2 production in DAN- patients = 800 +/- 144 ml/min). These results fell within our normal range for ventilatory response to transient hypoxia at this level of exercise. 4. The heart rate response to transient hypoxia varied within the groups but was significantly (P less than 0.05) less in the patients with established diabetic autonomic neuropathy. 5. We conclude that the peripheral chemoreceptors are intact in diabetic autonomic neuropathy and that other mechanisms must be implicated in the unexpected cardiorespiratory arrests seen in these patients.

Adult↗
PubMed1982

Alpha 2-macroglobulin and proliferative retinopathy in type 1 diabetes.

Serum alpha 2-macroglobulin (alpha 2m) and total glycosylated haemoglobin (HbA1) concentrations were measured in 110 insulin dependent Type 1 diabetics with minimal or no fundoscopic retinopathy, referred to as non-retinopaths, and in 52 proliferative retinopaths. Proteinuria was recorded in 8 (7%) non-retinopaths and 29 (56%) retinopaths and was accompanied by elevated alpha 2m concentrations in both groups of diabetics but only significantly so in the non-retinopaths. Diabetics without proteinuria showed a significant correlation between alpha 2m concentration and duration of diabetes, HbA1 and age (being higher at extremes of age). Alpha 2m concentrations were significantly higher in retinopaths than in non-retinopaths without proteinuria when allowance was made for the influence of age and duration of diabetes on alpha 2m. This difference may be attributed to the higher HbA, levels found in retinopaths than in non-retinopaths and was no longer evident when account was taken of the prevailing HbA1 concentration in individual patients.

Adult↗
PubMed1982

HLA antigens and other risk factors in the development of retinopathy in type 1 diabetes.

Factors possibly influencing the development of diabetic retinopathy were studied in 112 randomly selected type 1 diabetics having no or minimal retinopathy (group A) and in 82 type 1 diabetics with known severe diabetic retinopathy. The latter comprised those with severe background retinopathy (group B, n = 17) and those having proliferative retinopathy without (group C, n = 38) and with group D, n = 27) diabetic nephropathy. Nonretinopaths (group A) were of similar sex ratio, body weight, and age at diagnosis of diabetes but had been diabetic longer (p less than 0.001) and were thus older (p less than 0.001) than retinopaths (groups B-D). The distribution of HLA antigens of the A, B, and C loci was similar in nonretinopaths and retinopaths with the exception that HLA B7 showed a reduced (p less than 0.05) prevalence in the retinopaths (6% versus 17%) and was singularly underrepresented in group D, where no patients had this antigen. Mean postprandial plasma glucose and HbA1 concentrations were higher (p less than 0.01 and p less than 0.001) and cigarette smoking was more prevalent (p less than 0.01) in the retinopathy groups B-D than in group A. Systolic and diastolic blood pressures were similar in groups A-C, with higher (p less than 0.001) values only in group D. There was no association between insulin antibody binding in the serum or measurable plasma C-peptide immunoreactivity and retinopathy status. The risk of development of diabetic retinopathy in type 1 diabetes may be related to HLA-associated genetic factors and to cigarette smoking.

Adult↗
PubMed1982

The clinical features of diabetic impotence: a preliminary study.

Twenty-seven diabetic men with erectile impotence were given physical and psychosexual assessments. Physical assessment included vascular and neurological evaluation. Psychosexual assessment was by means of a semi-structured interview. Seven potent diabetic men formed a control group. Patients with erectile failure had a varied clinical picture which differed from the stereotype of diabetic impotence: morning erections were preserved in over a half (55 per cent), eight patients (30 per cent) had intact spontaneous erections, and sexual interest was reduced in 12 patients (44 per cent). In 13 patients (48 per cent) ejaculation was disturbed and a further four patients (15 per cent) described unusual disorders of sexual function. Within the group there were no differences in clinical picture between those with and without autonomic neuropathy, retinopathy or potential psychogenic factors.

Adult↗
PubMed1981

Heart rate changes in diabetes mellitus.

Resting heart rates were measured lying, sitting, and standing in 61 diabetics with varying degrees of cardiovascular reflex abnormalities. Those with parasympathetic abnormalities alone had the highest heart rates, while those with both parasympathetic and sympathetic involvement had slightly less rapid heart rates, which were still faster than those in diabetics with normal cardiovascular reflexes. 38 other diabetics in whom autonomic function tests had been done at least three times had a similar pattern of resting heart rate. 25 had unchanged tests: those with parasympathetic involvement alone had the highest heart rates. The other 13 subjects whose autonomic function changed from normal to abnormal showed a sequential increase in heart rate as cardiac parasympathetic damage developed, followed by a fall in heart rate, but not back to normal, as sympathetic damage developed as well. The increased resting heart rates in diabetics may be due in some patients to cardiac parasympathetic damage alone and in others to combined parasympathetic and cardiac sympathetic damage. The sequential heart rate changes support the view that the vagus nerve is affected before the cardiac sympathetic nerves.

Adolescent↗
PubMed1981

Diabetic control in patients treated with once or twice-daily insulin injections, including a comparison of conventional beef and highly purified pork insulins.

Twenty patients were changed from a single daily injection of beef insulin (a mixture of soluble and protamine zinc insulin) to two daily injections (mixtures of soluble and isophane insulins). This was associated with a reduction, one month later, in the concentration of glycosylated haemoglobin (HbA1) and in the degree of late evening glycosuria. A reduction was shown 6 months later in antibody binding of beef and pork insulin by serum. Subsequent conversion to a twice daily regime of highly purified pork insulin was not associated with further improvement in diabetic control, but was associated after 1 month with a reduction in daily insulin dose, and after 5 months with a further reduction in antibody binding of beef and pork insulin by serum. Patients failing to show a C-peptide response to intravenous glucagon had a fall in HbA1 after conversion from a once to a twice daily insulin regime, which correlated inversely with insulin antibody binding estimated at the beginning of the study.

Adolescent↗
PubMed1981

The clinical features of diabetes with coexisting autoimmune thyroid disease.

A study was made of the clinical features of diabetics with coexisting Graves' disease (n = 117) or primary hypothyroidism (n = 98). Those with Graves' disease developed thyroid dysfunction and diabetes at an earlier age than patients with primary hypothyroidism. There was, however, no difference between the two groups in respect of sex ratio nor proportion of subjects requiring insulin treatment. In contrast to the general diabetic population, 87% of diabetics with thyroid disease were female, 56% required insulin treatment and of patients requiring insulin from diagnosis, the median age at diagnosis of diabetes was 36 years. A strong correlation was observed between age at diagnosis of diabetes and that of hyperthyroidism (r = 0.71, p less than 0.001) or hypothyroidism (r = 0.65, p less than 0.001). With increasing age at diagnosis of diabetes the interval between diagnosis of diabetes and thyroid disease diminished. The mean +/- SEM interval between diagnosis of diabetes and that of thyroid dysfunction was longer in hypothyroid (6.7 +/- 1.2 years) than in hyperthyroid diabetics (-2.4 +/- 1.2 years). Neither insulin-dependent nor non-insulin dependent diabetics with associated thyroid disease exhibited a significant seasonal variation in diagnosis or symptomatic onset of diabetes. It is conceivable that where diabetes accompanies autoimmune thyroid disease in the same patient, both conditions may share a common and coincident pathogenesis which is unrelated to acute environmental influences.

Adolescent↗
PubMed1981

Cardiac autonomic neuropathy in diabetes: comparison of measures of R-R interval variation.

Five different methods of analysing R-R interval (heart rate) variation were compared, using a computer technique, in 61 diabetics with a wide range of responses to autonomic function testing. Two methods differentiated best between the diabetics with and without autonomic damage: (1) the standard deviation of the mean R-R interval recorded for 5 min during quiet breathing with the subject either sitting or standing; (2) the difference between the maximum and minimum heart rates recorded over 1 min during deep breathing at six breaths per minute, again with the subject either sitting or standing. For routine clinical usage we conclude that recording the heart rate for 1 min on an ECG, while the subject sits and breaths deeply at six breaths per minute, and then measuring the difference between the maximum and minimum heart rate, is the most practical method currently available. For research purposes either this method or the standard deviation method during quiet breathing for 5 min, should be used.

Adult↗