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Biomedical subjects

J D Best

Publications and source records attributed to J D Best.

101 records · Page 6Linked to original sources
PubMed1982

The effect of chronic sulfonylurea therapy on hepatic glucose production in non-insulin-dependent diabetes.

In 20 patients with untreated non-insulin-dependent diabetes mellitus (NIDDM), there was a positive relationship between fasting plasma glucose (FPG) and glucose production rate, calculated by the isotope dilution technique (r = 0.72, P less than 0.001). This suggests that glucose production rate is an important determinant of FPG in untreated NIDDM. Fifteen patients were also studied during therapy with chlorpropamide for 3-6 mo. During therapy, FPG was lower (133 +/- 9 vs. 216 +/- 20 mg/dl, mean +/- SEM; P less than 0.001), glucose production was lower (59.5 +/- 2.0 vs 77.6 +/- 4.9 mg/m2/min; P less than 0.005), and there was a significant correlation between the fall in glucose production and the fall in FPG (r = 0.59, P less than 0.05). Fasting IRI levels increased in some, but not all, patients during chlorpropamide (untreated 18 +/- 2, treated 21 +/- 2 muU/ml; P= NS). However, there was a significant relationship between the percent rise in IRI and the fall in glucose production during treatment (r = 0.75, P less than 0.001). Patients with a rise in fasting insulin during therapy had a greater fall in glucose production than those whose insulin did not rise (25.4 +/- 8.1 vs. 7.8 +/- 2.4 mg/m2/min; P less than 0.005). When a low-dose insulin infusion was given to approximate the increases of portal venous insulin during therapy, similar falls of glucose production occurred. We conclude that inhibition of endogenous glucose production during chronic chlorpropamide therapy is an important mechanism for the lowering of FPG and that enhanced insulin secretion is the reason for the major part of this inhibition. The small fall in glucose production in those patients whose insulin level did not rise during therapy suggests an additional contribution by some other mechanism.

Adult↗
PubMed1981

Incidence of hypothyroidism after radioactive iodine therapy for thyrotoxicosis in Hong Kong Chinese.

The incidence of hypothyroidism in 1396 Chinese patients in Hong Kong treated for hyperthyroidism with 131I therapy is presented using the life-table method of analysis. One year after therapy only 6% of patients were hypothyroid, but the subsequent annual incidence was 3.5%, emphasising the need for life-time surveillance of these patients. A higher incidence of subsequent hypothyroidism was found in patients with diffuse surgical treatment, the total dose or number of doses of 131I, the severity of thyrotoxicosis and the age of the patient did not influence the rate of onset of hypothyroidism. The data suggest that in order to minimise the occurrence of hypothyroidism a lower dose of 131I per gram of thyroid mass should be used for patients with small diffuse glands.

Adult↗
PubMed1981

Glucose disposal is not proportional to plasma glucose level in man.

Metabolic clearance rate (MCR) of glucose has been defined as the rate of glucose utilization divided by the glucose concentration. This model of glucose transport has been widely used as a measure of hormonally regulated glucose disposal, on the assumption that glucose disposal rate is proportional to glucose concentration. To test this assumption, the relationship between glucose concentration and disposal rate was studied in man during infusion of somatostatin +/- exogenous insulin to achieve fixed plasma insulin levels of 1, 18, and 46 microM/ml on separate days. When glucose concentration was increased to more than twice basal fasting levels, the glucose disposal rate increased significantly at all three insulin levels. However, the increase was not proportional to the rise in glucose concentration, and MCR fell by 38%, 16%, and 11% at the low, medium, and high insulin levels, respectively. These results are explained by an alternative model of glucose transport in which insulin-independent tissues such as brain have a relatively fixed glucose uptake, while other tissues have glucose transport systems which take up glucose at a rate proportional to its plasma concentration. We conclude that MCR of glucose is not a good measure of hormonally regulated glucose disposal because it is partially dependent on the glucose concentration, particularly at low insulin levels.

Adult↗
PubMed1980

Evaluation of the three hour metyrapone test in adults.

The prolonged metyrapone test is used to assess the hypothalamic-pituitary-adrenal axis. The dynamic responses of cortisol, ACTH and 11-deoxycortisol over the 3 h of the single morning dose metyrapone test have been examined in fourteen normal adult subjects. In every case there was a rapid, sustained fall in cortisol, but the resultant ACTH responses were extremely variable and in two subjects did not exceed values obtained during the control studies. The rise in 11-deoxycortisol was also variable and in several instances occurred without any significant elevation in ACTH. In these cases, the rise in 11-deoxycortisol may be due to a normal level of production of steroids with a shift from cortisol to 1-deoxycortisol induced by the metyrapone. Thus, the hypothalamic-pituitary-adrenal axis may not be adequately tested, and this together with the high incidence of unpleasant side effects, makes the 3 h oral metyrapone test unsatisfactory for routine use in adults.

Adrenocorticotropic Hormone↗
PubMed1978

Insulinoma: poor recognition of clinical features is the major problem in diagnosis.

Traditionally it is taught that hypoglycaemia may cause a clinical picture which mimics a variety of neurological and psychiatric disorders. Yet patients with insulinoma continue to baffle many medical specialists, who presumably are not sufficiently aware of the clinical features of hypoglycaemia. After examining medical records of seventeen patients, diagnosed as suffering from "insulinoma" in major Melbourne hospitals from 1971 to 1976, it was evident that these patients frequently undergo extensive investigations for supposed neurological disorders, the correct diagnosis being missed until they develop catastrophic symptoms. Of these seventeen patients, the diagnosis was made with reasonable speed in only six cases, while eight patients were initially discharged from hospital with a completely erroneous diagnosis. It seems likely that a number of patients with insulinoma, whose symptoms are less dramatic than those reported here, are being mistakenly treated as having epileptiform or psychiatric disorders.

Adenoma, Islet Cell↗
PubMedDate not supplied

Insulin resistance syndrome in Australian aboriginal people.

1. Like many indigenous populations, Australian Aboriginal people have developed high rates of obesity, non-insulin-dependent diabetes mellitus (NIDDM) and cardiovascular and renal disease following the transition from a traditional to an 'urbanized' lifestyle. These conditions tend to cluster as part of the insulin resistance syndrome. 2. The prevalence of overweight people and obesity in Australian Aboriginal populations ranges from 0% in communities with a traditionally orientated lifestyle to well over 50% in the worst affected communities. There is a predominantly central pattern of fat deposition in both men and women, which is associated with greater insulin resistance and cardiovascular risk than is peripheral fat deposition. 3. Data from four previously published, population-based surveys in Aboriginal communities were combined to give a cohort of 1079 subjects of 15 years and older. Several conditions of the insulin resistance syndrome had a strong, positive association with increasing body mass index (BMI): NIDDM (both cross-sectionally and longitudinally), hypertension, dyslipidaemia and albuminuria. Remaining lean (BMI < 20 kg/m2) protected even older Aboriginal people from these conditions to a large extent. 4. Community based programmes to increase physical activity and improve dietary quality are likely to be the major means by which conditions associated with insulin resistance can be prevented in Aboriginal populations.

Female↗
PubMedDate not supplied

Attitudes of diabetic men after implantation of a semi-rigid penile prosthesis.

Erectile impotence is a common and distressing problem in diabetic men. In order to examine the impact of a penile prosthesis on the quality of life of the recipients, we mailed a questionnaire to all patients (N = 49) who received a semi-rigid (Small-Carrion) prosthesis at the Seattle VAMC from 1976 to 1981. Fourteen patients with diabetes and 23 without diabetes returned the questionnaire. Direct comparisons showed no statistically significant differences between the responses of the two groups. Based on a scale of 1-7 (1 = worst, 4 = no change, 7 = best), the general effect of the operation on the quality of life of the recipients was 5.7 +/- 0.3 (Mean +/- SEM); the quality of intercourse was 5.1 +/- 0.3; the patient's perception of his partner's response to the prosthesis was 5.2 +/- 0.3; and the patient's perception of postoperative changes in his relationship with his partner was 5.6 +/- 0.3. Eighty-three percent of the patients were satisfied with the performance of the prosthesis. Most of the patients (86%) felt that their preoperative expectations had been fulfilled and would elect to have the procedure if they had it to do over again. However, five patients (14%) stated that they would not elect the operation again because their partners did not appreciate the operation (N = 2); the operation produced severe, prolonged pain (N = 1); or the patient's expectations had not been fulfilled (N = 2). Preoperative counseling should be used to foster realistic patient and partner expectations. This operation, which appears to improve the quality of life for most diabetic patients with erectile impotence, should be considered a part of standard care and not as a cosmetic procedure or extraordinary care.

Coitus↗
PubMedDate not supplied

Acute and chronic effects of sulfonylurea drugs on pancreatic islet function in man.

The pancreatic islet can be viewed as an integrator of nutrient, neural, and hormonal signals. In normal people, glucose directly stimulates insulin release and also plays a key role as a potentiator of nonglucose stimulants of the B-cells. In patients with non-insulin-dependent diabetes mellitus (NIDDM), the direct effect of glucose on insulin secretion is markedly impaired. However, as hyperglycemia develops, basal insulin levels and insulin responses to nonglucose signals are maintained in many NIDD patients by the potentiating effect of hyperglycemia. Both acute and chronic administration of sulfonylurea drugs results in enhanced B-cell sensitivity to the potentiating effect of glucose. During sulfonylurea therapy this effect initially causes an increase in insulin level. However, as the glucose level falls during therapy the insulin level may tend to return toward pretreatment values, thereby masking the improvement of B-cell function. In NIDD patients with mild to moderate hyperglycemia (fasting plasma glucose less than 200 mg/dl), chronic sulfonylurea therapy results in the maintenance of near-normal insulin levels, but at a lower plasma glucose level. In patients with more severely impaired B-cell function, whose insulin levels before therapy are subnormal despite marked hyperglycemia, there is a net absolute increase in insulin levels during chronic sulfonylurea administration. Thus, some NIDD patients may show an increase in basal insulin levels during chronic sulfonylurea therapy while others may not; however, all patients who respond to sulfonylureas demonstrate increased B-cell sensitivity to glucose. Acute and chronic sulfonylurea treatment also results in a suppression of glucagon levels, an effect that may be secondary to the enhancement of B-cell function. The fall of plasma glucose during chronic sulfonylurea therapy is associated with a decrease in hepatic glucose production in NIDD patients. The magnitude of this effect is correlated with the degree of enhancement of basal insulin secretion. Thus, chronic sulfonylurea therapy clearly enhances pancreatic islet function in patients with NIDDM. We postulate that the major antihyperglycemic action of sulfonylurea therapy is mediated by this pancreatic effect.

Chlorpropamide↗