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Biomedical subjects

N W Oakley

Publications and source records attributed to N W Oakley.

At least 19 recordsLinked to original sources
PubMed1982

Diurnal profiles of plasma magnesium and blood glucose in diabetes.

In order to study the relation between plasma magnesium and blood glucose concentrations in diabetes, diurnal profiles were obtained in nine diabetic patients and five healthy subjects. A significant inverse relationship between the two variables was found in seven of the nine diabetic patients and in one healthy subject. This could not be attributed solely to changes in plasma albumin, and its mechanism is unclear. Plasma magnesium levels in diabetes are closely dependent on blood glucose concentration.

Adolescent↗
PubMed1980

Screening for diabetes during pregnancy.

Blood was taken for plasma glucose estimation one hour after oral ingestion of 50 g of glucose in 948 of 970 women booking at an antenatal clinic during one year. An abnormal result (greater than or equal to 7.7 mmol/l) was obtained in 74 subjects of whom 68 subsequently had an oral glucose tolerance test. Fourteen of these women (1.5 per cent of the study population) were found to have chemical diabetes.

Adult↗
PubMed1980

Evaluation of plasma glucose control in pregnancy complicated by chemical diabetes.

Two-hourly plasma glucose measurements were made over a 24-hour period in 24 pregnant women with chemical diabetes treated by dietary carbohydrate restriction alone. The values obtained between midnight and 0600 hours displayed the best correlation with the mean of the diurnal values, the strongest individual correlation being at 0200 hours. During the daytime, the mean of the plasma glucose values before breakfast (0600 hours) and lunch (1200 hours) and two hours after supper (2000 hours) provided the strongest correlation with the mean diurnal value and these are recommended as the routine sampling times for assessment of diabetic control in pregnant women with dietary treatment for chemical diabetes.

Adult↗
PubMed1979

Comparison of effects of different combined oral-contraceptive formulations on carbohydrate and lipid metabolism.

Oral glucose-tolerance tests were performed and fasting serum cholesterol and triglyceride levels measured in 1628 Caucasian women taking combined oestrogen/progestagen oral contraceptives (o.c.) and 577 women not taking O.C. The former were divided into six groups according to the composition of the O.C Glucose tolerance deteriorated in all O.C. groups containing oestrane progestagens (nortestosterone-derived) or the gonane, norgestrel, but was unaltered by O.C. containing a pregnane progestagen (derived from progesterone). The greatest deterioration was with O.C. containing 75 microgram or more oestrogen, and this was associated with impairment of the early insulin response to glucose. In O.C. containing a pregnane progestagen insulin secretion was unaffected. In the remaining O.C. groups insulin secretion was increased; this was most pronounced with the O.C. containing a gonane progestagen. Serum-cholesterol was elevated only with O.C. containing 75 microgram or more oestrogen and an oestrane progestagen and tended to be lower in O.C. containing a gonane progestagen. O.C.-induced hypertriglyceridaemia was oestrogen-dose-related, and this effect was potentiated by the pregnane progestagen. The gonane progestagen antagonised oestrogen-induced hypertriglyceridaemia.

Adult↗
PubMed1978

Metabolic effects of beta-sympathomimetic drugs and dexamethasone in normal and diabetic pregnancy.

Marked hyperglycaemia and hyperinsulinaemia were observed in two normal women in premature labour treated with an intravenous infusion of a beta-sympathomimetic drug and intramuscular dexamethasone injections. Similar therapy in a chemical diabetic patient caused diabetic ketoacidosis, while treatment of an insulin dependent diabetic with dexamethasone alone resulted in a major increase in her insulin requirements. It is suggested that the diabetogenic effects of beta-sympathomimetic drugs and dexamethasone may be additive and that regular plasma glucose estimations should be made when they are used, especially in patients with impaired glucose tolerance.

Adolescent↗
PubMed1977

Diurnal plasma free fatty acid profiles in normal and diabetic pregnancies.

Diurnal plasma free fatty acid (FFA) and glucose concentrations were measured in 23 normal women, 13 chemical diabetics, and 11 insulin-dependent diabetics in late pregnancy. The mean diurnal FFA value was lowest in the insulin-requiring diabetics and highest in the chemical diabetics. Although no association was found between percentile birthweight and maternal mean fasting or diurnal FFA, there was a positive correlation between percentile birthweight and both mean maternal fasting plasma glucose and mean diurnal glucose in normal and chemical diabetic women. These observations support the view that glucose is the major substrate used by the fetus, but birthweight may be influenced more by the total substrate crossing the placenta than by maternal levels of either glucose or FFA alone.

Adult↗
PubMed1977

Plasma human placental lactogen profiles over 24 hours in normal and diabetic pregnancy.

Plasma human placental lactogen (HPL) concentrations have been measured at frequent intervals over 24 hours in 24 normal women, 13 chemical and 13 insulin dependent diabetic patients during the third trimester of pregnancy. Most of the women studied displayed variation in HPL levels during the day, but there was no evidence of a diurnal rhythm, nor significant changes following meals or during the nocturnal fast. The mean plasma HPL concentrations over 24 hours in the chemical and insulin dependent diabetic patients (5-9+/-SD 1-3 and 5-9+/-1-7 microng/ml respectively) were greater than those in normal women (5-1+/-1-2 microng/ml) but this difference was not significant. No significant change in plasma HPL concentrations was observed during a five-hour oral glucose tolerance test in either the normal or chemical diabetic group. It is suggested that in normal pregnant women HPL does not itself contribute to glucose homeostasis but acts as a 'regulator' which alters the actions of certain maternal hormones to achieve a favourable environment for fetal growth.

Adult↗
PubMed1976

Effect of "fractionated" insulins on total plasma insulin binding capacity and insulin requirements in severe diabetes.

Serial observations of insulin requirement and total plasma insulin binding capacity have been carried out on six xevere diabetics whose treatment was changed from standard soluble and isophane (NPH) insulins to "fractionated" preparations (Nordisk Insulin Ltd). No correlation was found between initial insulin dose and binding capacity, but changes in these two functions during the study period were closely correlated, both for the group as a whole and for individual patients in whom falls in insulin dose occurred. It is concluded that highly purified insulins could be valuable in the treatment of insulin-resistant cases, that their use is frequently associated with a gradual reduction in insulin dose, and that estimation of total plasma insulin binding capacity may indicate which patients are most likely to benefit from fractionated insulin. No sudden change in insulin requirement was seen on changing to purified insulin preparations.

Adult↗
PubMed1975

Insulin metabolism, insulin sensitivity and hormonal responses to insulin infusion in patients taking oral contraceptive steroids.

The metabolism of unlabelled human monocomponent insulin was studied in a group of six patients being treated with combined oestrogen-progestogen oral contraceptives (OC) and compared with a group of ten normal subjects. The parameters of insulin metabolism were determined by a priming dose-continuous infusion technique which enabled measurements of metabolic clearance rate (MCR) of insulin to be made at four separate steady state hormone concentrations spanning the physiological range. In normal subjects MCR was greatest at low insulin concentrations, falling from 24.7 ml/kg/min. at 16 muU/ml to 11.4 ml/kg/min. at a mean concentration of 280 muU/ml. In the OC group, MCR averaged 20.5 ml/kg/min. and did not change with increasing plasma insulin concentration. The plasma half-disappearance time (T 1/2) was longer than normal in the OC group (5.6 vs. 4.4 min., p less than 0.05) despite a higher MCR. The prolonged T 1/2 indicated that the apparent distribution space was increased in those on OC (166.6 vs. 82.7 mg/kg., p less than 0.0025). The results are interpreted as indicating increased capillary permeability to insulin and increased peripheral degradation. The fact that MCR did not fall in the OC group with increasing plasma insulin concentrations whereas it did in normal subjects, suggested that OC leads to the loss of saturable component of insulin degradation that is present in normal subjects. Insulin sensitivity (as judged by induced hypoglycaemia) was reduced in the OC group while growth hormone responses were within the normal range. Plasma cortisol was increased in those taking OC but the response to insulin induced hyperglycaemia was less marked than normal. The results indicate a significant alteration in insulin metabolism in these subjects, which may contribute to the impairment of carbohydrate tolerance seen in some women taking combined OC.

Adult↗
PubMed1975

Carbohydrate metabolism in pregnancy. Part I. Diurnal plasma glucose profile in normal and diabetic women.

Diurnal plasma glucose profiles and oral glucose tolerance during pregnancy were studied in normal women, chemical diabetics, and insulin-requiring diabetics. In normal women the mean diurnal plasma glucose rose by only 0.22 mmol/1 (4 mg/100 m1) during pregnancy. Mild chemical diabetes resulted in an increase in both the mean diurnal glucose concentration and the fluctuation of plasma glucose levels during the day. Fluctuation in glucose concentration in insulin-dependent diabetics was about three times that found in non-diabetic women of similar gestation, with relative hyperglycaemia during the day and hypoglycaemia at night. In non-diabetic women and those with chemical diabetes the mean dirunal glucose correlated closely with the total area under the three-hour oral glucose tolerance curve and significantly, but less closely, with the two-hour glucose tolerance test value.

Blood Glucose↗
PubMed1975

Diabetic retinopathy.

Retinopathy is present in 60%-80% of long-term diabetics, and 5%-10% of diabetics surviving 20 yr from the time of diagnosis will be blind, mostly from retinopathy, which is now the commonest cause of newly diagnosed blindness in the 30-65 yr age group. The mean survival time after a diagnosis of retinopathy is only 5 yr. The natural history of diabetic retinopathy is now being understood more clearly. Mild background retinopathy, characterised by microaneurysms or scattered hard exudates, may progress to maculopathy, with macular vascular pathology leading to exudates and edema at the macula; this is most common in older patients. It may also lead to proliferative retinopathy, which may progress slowly with new vessels and fibrous-tissue formation, or rapidly with widespread capillary closure and soft-exudate formation, extensive neovascularisation, hemorrhages, and blindness. The changes of diabetic retinopathy can be documented using retinal photography, and several grading methods have been devised that are useful for evaluation treatment. The cause of diabetic retinopathy is still unclear. Evidence for incriminating genetic factors, growth-hormone excess, and hypoxia associated with changes in blood flow and retinal metabolism are reviewed. Insulin responses and plasma triglyceride seem to be different in maturity-onset diabetics with retinopathy when compared with those in whom this complication is absent. Most physicians agree that good diabetic control may both lower the incidence of retinopathy and reduce the speed of its progress. While there is little evidence that drugs are ever of much value in this condition, the role of photocoagulation both by laser and xenon arc is becoming clearer with increased experience of these techniques, and the current situation is reviewed. Pituitary ablation is a very drastic method of treatment and should never be used as a desperate measure in a patient with advanced proliferative disease. It is, however, the treatment of choice in early florid retinopathy, when it proves the only chance to arrest the condition. Some new techniques of vitreous surgery are now being developed and the possible role of these in the management of patients with advanced proliferative disease is briefly reviewed.

Adult↗
PubMed1975

The treatment of acromegaly with special reference to trans-sphenoidal hypophysectomy.

Experience in the management of 100 cases of acromegaly is described. Three quarters of these had been referred directly to the endocrine clinic at the Middlesex Hospital. The remainder were referred from the Royal Post-graduate Hospital because they were thought unsuitable for yttrium implantation. The patients were studied by clinical assessment of severity, by measurement of basal growth hormone levels on three separate mornings, and by a review of possible complications. Particular attention was paid to diabetes, hypertension, cardiomegaly, respiratory, vascular and skeletal changes as well as visual field defect. Aggressive treatment was recommended in 77 patients. It was not recommended in the remainder on account of age, intercurrent illness or the apparent mildness of the condition. Fifty-nine patients were treated by trans-sphenoidal hypophysectomy. In 46 of the 59 patients the mean basal growth hormone level has been reduced to 5 ng/ml or less. In 39 this followed operation, in five operation and subsequent X-ray therapy and in two operation and the continuing effect of previously implanted yttrium. Of these 46 patients in whom the growth hormone level has been reduced to normal, 26 do not show any deficiency of anterior pituitary trophic hormones, 13 have gonadotrophin defect (in eight of these it was present before the operation) and seven require full replacement therapy. One patient died at home six weeks after the operation from a pulmonary embolus. There was one case of CSF rhinorrhoea which stopped spontaneously and three of acute frontal sinusitis. Trans-sphenoidal hypophysectomy is shown to be an effective means of treating acromegaly. If the basal level of growth hormone is not reduced to normal by six weeks after operation, it is recommended that a course of X-ray therapy should be given. This does not apply if irradiation has been used before operation.

Acromegaly↗