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Biomedical subjects

H C Simpson

Publications and source records attributed to H C Simpson.

At least 19 recordsLinked to original sources
PubMed1992

Screening programme for microvascular complications and hypertension in a community diabetic population.

The role of a community-based screening programme for microvascular complications of diabetes and hypertension was evaluated in the semi-rural town of Trowbridge (population 31,000). Of 405 diabetic patients identified (prevalence 1.31%), 358 (88%) attended for screening, 94 (26%) of whom were under hospital review for diabetes. In only 136 patients (38%) were all aspects of diabetes care found to be satisfactory. The remaining 222 patients included 162 patients with poor metabolic control (HbA1 greater than or equal to 12%), 118 who were hypertensive at screening, 13 with previously undiagnosed diabetic nephropathy, and 29 with undiagnosed potentially sight-threatening retinopathy. Overall standards of diabetes care in this community population appear inadequate, and might be improved by introduction of a simple screening programme for diabetic complications.

Adult↗
PubMed1990

Combination of insulin with glipizide increases peripheral glucose disposal in secondary failure type 2 diabetic patients.

Twenty Type 2 diabetic patients, recently converted to insulin because of inadequate control on oral hypoglycaemic agents, were studied. Endogenous insulin reserve was measured by glucagon stimulation, and insulin-mediated peripheral glucose disposal by a hyperglycaemic (11 mmol l-1) clamp, measurements being repeated after 8 weeks of glipizide or placebo therapy in addition to the patients' usual insulin. The study was randomized and double blind. Fasting and stimulated C-peptide levels did not change on glipizide or placebo. Insulin-mediated glucose disposal rose from 2.5 (1.5-8.0) (median (range] to 4.2 (2.3-8.4) mg kg-1 min-1 in the glipizide group (n = 9, p less than 0.01), but did not change in the placebo group. Glycosylated haemoglobin did not change in either group, but median fasting plasma glucose fell from 10.6 (6.1-15.1) to 9.0 (6.4-11.2) mmol l-1 in the glipizide group (p less than 0.02). Fasting insulin rose on glipizide from 10.1 (4.0-23.2) to 13.0 (6.4-33.8) mU l-1 (p less than 0.02). Insulin dosage fell in the glipizide group from 36 to 26 U day-1, as 4 patients experienced hypoglycaemic symptoms. HDL-Cholesterol fell in all patients on glipizide, from 0.94 (0.79-2.13) to 0.79 (0.62-1.95) mmol l-1 (p less than 0.01). Combination of insulin with the sulphonylurea glipizide in secondary failure Type 2 diabetic patients leads to increased insulin-mediated peripheral glucose disposal. Glipizide may have an adverse effect on HDL-cholesterol, which is unrelated to change in diabetic control.

Aged↗
PubMed1987

Endogenous vasopressin affects postural control of blood pressure in man.

1. Six healthy volunteers received intravenous infusions of isotonic (0.9% NaCl) and hypertonic (3% NaCl) saline on separate days. There were no significant changes in blood pressure or forearm blood flow, despite an increase in plasma arginine vasopressin (AVP) during hypertonic saline. 2. Immediately and 10 min after passive tilting to 50 degrees, mean forearm blood flow fell by 17.1 and 14.3% compared with the values in the supine position during isotonic saline and by 40.3 and 43.3% during hypertonic saline. Forearm vascular resistance rose by 23.6 and 17.8% with isotonic saline and by 80.2 and 88.2% with hypertonic saline for the two readings in the tilted compared with the supine position. 3. Tilting was associated with a 14.9 and 12.1% rise in diastolic blood pressure immediately and 10 min after assuming this position during hypertonic saline, and a rise of 6.4% in mean arterial pressure. 4. The results from this study are similar to those obtained previously, when small amounts of AVP were infused. They provide further evidence that AVP may have a physiological role in the postural regulation of blood pressure.

Adult↗
PubMed1986

Haemodynamic effects of vasopressin in man are related to posture.

Ten healthy volunteers received intravenous infusions of arginine vasopressin (AVP) at 0.1 m-unit min-1 kg-1 and 5% D-glucose on separate days. AVP caused a small fall in forearm blood flow and small rises in mean arterial pressure and systemic vascular resistance. Cardiac output was unaffected. When subjects were tilted to 50 degrees the fall in forearm blood flow was much greater, mean fall being 44.8% with AVP compared with 18.2% with D-glucose. Cardiac output also fell significantly more with AVP, and diastolic pressure, mean arterial pressure and systemic vascular resistance rose significantly more on tilting during AVP infusion than with D-glucose. Six of the same volunteers were given sequential infusions of 'low dose' (0.0125 m-unit min-1 kg-1) and 'high dose' (0.3 m-unit min-1 kg-1) AVP on a third occasion. Tilting still produced a mean fall in forearm blood flow of 41.2% during low dose infusion, despite a mean plasma AVP level of only 1.9 pg/ml, which is well within the physiological range. When the AVP concentration was increased 24-fold to the high dose, forearm blood flow fell only a further 8.8%. The low dose infusion was also associated with a marked fall in cardiac output on tilting and a rise in systemic vascular resistance. We conclude that AVP has profound haemodynamic effects in man at physiological concentrations. Although these effects are modest in the supine position, they become marked on tilting, suggesting a possible role for AVP in the postural control of blood pressure.

Adult↗
PubMed1984

A comparison of cholestyramine and probucol in the treatment of familial hypercholesterolaemia.

Twelve patients with familial hypercholesterolaemia (FH) who had not achieved satisfactory cholesterol levels on dietary advice alone were treated with cholestyramine for 6 months and probucol for 6 months in a randomised cross-over study to compare the relative effectiveness of the two drugs. Over the 6-month period, mean total cholesterol fell by 16.4% on cholestyramine and 12.7% on probucol. Cholestyramine produced a 17.4% fall in low density lipoprotein (LDL) cholesterol, no significant changes in very low density lipoprotein (VLDL) cholesterol or high density lipoprotein (HDL) cholesterol, a 21.4% increase in HDL cholesterol subfraction HDL2 and a 24.1% increase in the HDL/LDL cholesterol ratio. Triglyceride levels rose by 29.6% but remained within the normal range. Probucol produced a 11.7% fall in LDL cholesterol, a 9.9% fall in VLDL cholesterol, a 10% fall in total HDL cholesterol, a 37% fall in HDL cholesterol subfraction HDL2 and no change in the HDL/LDL cholesterol ratio. Triglyceride levels fell by 14%. The mean corrected QT interval increased from 0.418 to 0.434 s (P less than 0.01) on probucol but did not change significantly on cholestyramine (from 0.405 to 0.41 s). The two drugs have different metabolic effects on FH. Cholestyramine has a more marked effect on LDL cholesterol, favourably influences the HDL/LDL cholesterol ratio and is therefore considered to be the drug of choice.

Cholesterol↗
PubMed1983

Hypertriglyceridaemia and hypercoagulability.

18 patients with severe hypertriglyceridaemia (mean fasting plasma triglyceride 5.7 mmol/l) had significantly higher concentrations of plasma fibrinogen and clotting factor Xc than did a normolipidaemic comparison group. Fibrinolytic activity was significantly lower in the hyperlipidaemic patients. Six months of treatment (diet or diet and clofibrate) lowered the patients mean plasma triglyceride to 3.1 mmol/l and caused a fall of clotting factors VIIc and Xc and a significant rise in fibrinolytic activity. None of these variables changed in the comparison group. Raised fibrinogen and factor VIIc concentrations are risk factors for cardiovascular mortality, and raised factor Xc and lowered fibrinolytic activity have both been found in groups at high risk of ischaemic heart-disease. Despite the fact that in population studies triglycerides do not consistently appear to be an independent risk factor for ischaemic heart disease, these data suggest that a pronounced increase in triglycerides warrants energetic therapy because it may be associated with a "hypercoagulable state".

Adult↗
PubMed1982

Low dietary intake of linoleic acid predisposes to myocardial infarction.

Thirty-two men who had recently had a myocardial infarction were matched individually for age with controls who had no evidence of heart disease. The patients had a significantly lower proportion of linoleic acid and a higher proportion of palmitic acid in their plasma triglyceride fatty acids. Analysis of the composition of red-cell membrane phosphatidyl choline, which reflects long-term dietary fat intake, showed a significantly lower proportion of linoleic acid in the patients.These differences suggest that the type of dietary fat consumed might be an important factor in the genesis of ischaemic heart disease.

Adult↗
PubMed1982

Digestible carbohydrate--an independent effect on diabetic control in type 2 (non-insulin-dependent) diabetic patients?

Many studies have shown high carbohydrate, high fibre diets to benefit diabetic control, the improvement being attributed mainly to an effect of fibre. This study investigated the possible beneficial effects of the digestible carbohydrate component. A diet rich in carbohydrate was compared with a traditional low carbohydrate diet in 10 Type 2 (non-insulin-dependent) diabetic patients, using a crossover design; both diets contained less than 20 g dietary fibre/day. During 24-h metabolic profiles carried out after 4 weeks on each diet, the mean basal plasma glucose (mean of 03.00, 05.00 and 07.00 h values) was 5.3 mmol/l on the high carbohydrate diet and 5.9 mmol/l on the low carbohydrate diet (p less than 0.05), despite the 2-h post-prandial glucose (mean of three main meals) being higher on the high carbohydrate diet than on the low carbohydrate diet (8.7 versus 7.3 mmol/l, p less than 0.01). Overall diabetic control was the same throughout the study, as judged by a mean 24-h plasma glucose of 6.7 mmol/l on the high carbohydrate and 6.6 mmol/l on the low carbohydrate diet, and haemoglobin A1c percentage of 8.3 on both diets. Mean cholesterol was 4.55 mmol/l on both diets and fasting plasma triglyceride was 2.83 mmol/l on the high carbohydrate and 2.55 mmol/l on the low carbohydrate diet (p = NS). These results indicate that a diet rich in carbohydrate, but restricted in fibre, does not cause overall deterioration of diabetic control or lipid metabolism in stable Type 2 diabetic patients, and suggest that digestible carbohydrate has an effect on basal blood glucose independent of fibre.

Aged↗
PubMed1982

Insulin receptor binding increased by high carbohydrate low fat diet in non-insulin-dependent diabetics.

In comparison to a traditional low carbohydrate diet (LC), the effect of an isocaloric high carbohydrate, high fibre diet (HC) upon the insulin binding to mononuclear blood cells of seven non-insulin-dependent diabetics was examined. Each subject, in random order, took both diets for 6 weeks each. There was no significant difference in weight during either dietary period, but a significant (P less than 0.05) increase in the monocyte insulin binding activity on the HD diet (tracer specific binding: 4.2% HC; 3.5% LC). This was accompanied by a significantly (P less than 0.02) lower fasting plasma glucose concentration (LC = 7.1 mmol/l; HC = 6.1) without a significant change in the fasting plasma insulin level. In contrast to the usual low carbohydrate diet, a high carbohydrate diet tends to correct the lowered insulin receptor status observed in maturity-onset diabetics.

Body Weight↗
PubMed1981

A high carbohydrate leguminous fibre diet improves all aspects of diabetic control.

In a randomised cross-over study 18 nondependent (NIDDM) and 9 insulin-dependent (IDDM) diabetics were put on to a high carbohydrate diet containing leguminous fibre (HL) for 6 weeks, and also a standard low carbohydrate diet (LC) for 6 weeks. During two identical 24 h metabolic profiles mean preprandial and mean 2 hour postprandial blood glucoses were significantly lower on HL in both groups, as were also several overall measures of diabetic control, including the degree of glycosuria. Total cholesterol was reduced significantly on HL in both groups, and the HDL/LDL cholesterol ratio increased significantly on HL in the NIDDM group. A diet high in complex carbohydrate and leguminous fibre improves all aspects of diabetic control, and continued use of a low carbohydrate diet no longer appears justified.

Adult↗