Biomedical subjects
V J Parfitt
Publications and source records attributed to V J Parfitt.
Outpatient assessment of residual growth hormone secretion in treated acromegaly with overnight urinary growth hormone excretion, random serum growth hormone and insulin like growth factor-1.
OBJECTIVE: To assess the outpatient investigations, overnight urinary growth hormone (uGH) excretion, random serum GH and insulin like growth factor 1 (IGF-1), and GH indices from the oral glucose tolerance test (OGTT) (fasting, nadir and mean GH), as measures of mean GH secretion in treated acromegaly, in comparison with a GH day series, which served as a gold standard. DESIGN: Prospective cross-sectional study, with patients admitted to a metabolic ward for the following investigations: random GH, IGF-1, 6 point GH day series (day 1), 9 h timed overnight uGH excretion, OGTT with GH response (day 2). Agreements between the mean GH during the day series and the other outcome measures, and the diagnostic performance of the latter, for the presence or absence of active acromegaly (mean GH during day series > or = 5 or < 5 mU/l, respectively) were determined. PATIENTS: 26 patients with treated acromegaly (11 with inactive acromegaly off drug therapy). MEASUREMENTS: Serum GH and uGH were measured by immunoradiometric assays and IGF-1 by radioimmunoassay. RESULTS: Agreements with the mean GH during the day series were perfect for the nadir GH during the OGTT with a 2 mU/l cutoff (Cohen's kappa (kappa) = 1, P < 0.00001), almost perfect for the fasting and mean GH throughout the OGTT (both kappa = 0.92, P < 0.0001) and random GH (kappa = 0.85, P < 0.0001), and substantial for the nadir GH with a 5 mU/l cutoff (kappa = 0.77, P < 0.0001), IGF-1 (kappa = 0.62, P < 0.001) and overnight uGH excretion (kappa = 0.61, P = 0.002). Nadir GH with a 2 mU/l cutoff was completely accurate for diagnosing the presence or absence of active acromegaly (positive and negative predictive values (% +/- standard error percentage) 100 +/- 8% and 100 +/- 10%). None of the outpatient tests used alone was an adequate diagnostic test (positive and negative predictive values: overnight uGH excretion -86 +/- 10% and 75 +/- 13%; random GH -100 +/- 11% and 85 +/- 11%; IGF-1 -92 +/- 10% and 71 +/- 13%) and so combinations of tests were assessed. The best was overnight uGH excretion plus random GH (positive and negative predictive values 88 +/- 9% and 100 +/- 12%). Using all three outpatient investigations, the positive predictive value of three raised results was 100 +/- 13%. CONCLUSIONS: In treated acromegaly, residual GH secretion can be reliably assessed with the OGTT, using standard diagnostic criteria. It can also be assessed on an outpatient basis with overnight uGH excretion and random GH, as direct measures, and IGF-1. If these are all normal, active acromegaly is excluded. Three raised results denote active acromegaly, and one or two raised results would need further investigation with a GH day series.
Effect of a very low fat diet on lipid peroxidation indices.
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Effect of a high fat meal on lipid peroxidation products.
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Use of thrombolysis for acute myocardial infarction in the presence of diabetic retinopathy in the UK, and associated ocular haemorrhagic complications.
Diabetic retinopathy is still regarded as a relative contraindication to the use of thrombolysis for myocardial infarction because of a perceived risk of intraocular haemorrhage. However, this complication has rarely been reported and the risk may be too small to justify withholding thrombolysis. A questionnaire survey was therefore conducted of members of the Medical and Scientific Section of the British Diabetic Association (BDA), to ascertain the exclusion criteria applied to the use of thrombolysis in patients with diabetic retinopathy in the UK and to identify any related ocular haemorrhagic complications. Replies were received from 128 physicians in 107 centres. Exclusion criteria applied were: any retinopathy 7 (5%), proliferative retinopathy and recent vitreous or pre-retinal haemorrhage 74 (58%), recent vitreous haemorrhage only 25 (20%), thrombolysis given regardless of retinopathy 22 (17%). No cases of intraocular haemorrhage following thrombolysis in diabetic myocardial infarction patients were identified. The risks of this complication appear to be very small and probably do not justify withholding thrombolytic therapy from diabetic patients with most forms of retinopathy, including proliferative.
Antioxidants in the Mediterranean diet.
It has been suggested that antioxidant vitamins or other antioxidants might inhibit the oxidation of low density lipoproteins into a particularly atherogenic form and preserve endothelial function. Antioxidants in the Mediterranean diet have been evaluated in relation to cardiovascular disease protection in this area. Observational epidemiologic data obtained from case-control, cohort or cross-cultural studies have consistently suggested that persons, such as those living in the Mediterranean area, who consume large amounts of antioxidant vitamins have a lower than average risk of cardiovascular disease. In another cross-cultural comparison, dietary intake, antioxidant status and plasma lipid peroxidation were compared in healthy young persons in Naples (Southern Italy) who consumed typical regional foods, and in Bristol (UK). The Naples group consumed more tomatoes and tomato juice, a higher proportion of monounsaturated fatty acids (from olive oil) and had a higher level of lipid antioxidant vitamin E (P = 0.005) and of beta carotene (P < 0.001) than the Bristol group. The intake of vitamin C, fresh fruit and vegetables, plasma vitamin A, serum selenium and copper levels did not differ. Several indices of plasma lipid peroxidation were significantly lower in the Naples group: conjugated dienes (P < 0.001), diene conjugation index (P = 0.019), lipid peroxides (P < 0.001). Dietary habits leading to relatively low levels of oxidized lipoproteins might contribute to the lower risk of coronary artery disease in Southern Italy.
A comparison of antioxidant status and free radical peroxidation of plasma lipoproteins in healthy young persons from Naples and Bristol.
Ischaemic heart disease mortality is much lower in Southern Italy than in the U.K. and this is not entirely explained by differences in classical risk factors. Differences in antioxidant intake, affecting free radical peroxidation of plasma lipoproteins, may be relevant. Therefore, dietary intake, antioxidant status and plasma lipid peroxidation were compared in healthy young persons eating typical regional diets from Naples (22) and Bristol (26). The Naples group consumed more fresh tomatoes, more fat as monounsaturates (from olive oil) and had higher plasma levels of the lipid antioxidants vitamin E (mean (SD; 95% CI) 29.1 (4.5; 26.8 to 31.3) vs 25.1 (3.86; 23.4 to 26.8) mumol.l-1, P = 0.005) and beta-carotene (4.74 (1.2; 4.14 to 5.34) vs 2.85 (0.8; 2.5 to 3.2) mumol.l-1, P < 0.001). Intakes of vitamin C, total uncooked fruit and vegetables, plasma vitamin A, serum selenium and copper levels were similar. All indices of plasma lipid peroxidation were significantly lower in the Naples group: conjugated dienes (median (interquartile range; non-parametric 95% CI)) 29 (21.5-39.9; 24 to 36.7) vs 41.5 (37-48.5; 38 to 44.5) mumol.l-1, P < 0.001; diene conjugation index 1.38 (1.02-1.55; 1.06 to 1.49) x 10(-2) vs 1.57 (1.43-1.74; 1.44 to 1.71) x 10(-2), P = 0.019; lipid peroxides (geometric mean (95% CI) 1.24 (1.12 to 1.37) vs 4.58 (3.84 to 5.46) mumol.l-1, P < 0.001.(ABSTRACT TRUNCATED AT 250 WORDS)
Benign intracranial hypertension after pituitary surgery for Cushing's disease.
An 11 year old girl underwent successful transsphenoidal pituitary adenomectomy for pituitary-dependent Cushing's syndrome. Three months after operation, just after stopping glucocorticoid replacement therapy, she developed benign intracranial hypertension. This resolved when exogenous glucocorticoids were restarted but occurred again when they were later stopped. On restarting glucocorticoids again, this second episode of intracranial hypertension resolved. This complication may have been due to the large fall in endogenous cortisol production after removal of her adenoma and subsequent persistent mild endogenous hypocortisolism.
The effects of high monounsaturated and polyunsaturated fat diets on vascular endothelium and the coagulation system in non-insulin dependent diabetes mellitus--related to changes in lipid peroxidation?
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Use of fructosamine and glycated haemoglobin to verify self blood glucose monitoring data in diabetic pregnancy.
Relationships between fructosamine and HbA1, and mean blood glucose over the previous 1-8 weeks, determined from self blood glucose monitoring with memory meters, were studied prospectively throughout 16 pregnancies in Type 1 diabetic women. Fructosamine correlated best (Spearman rank) with mean blood glucose over the previous 2 weeks in the first and second trimesters (0.5) and over the previous 1 week in the third trimester (0.39). HbA1 correlated best with mean blood glucose over the previous 8 weeks in the first and second trimesters (0.56), but over the previous 2 weeks in the third trimester (0.524) probably because of increased erythropoiesis in late pregnancy. From Deming regression models, 95% prediction intervals for mean blood glucose for fructosamine and HbA1 values were calculated, showing that fructosamine predicted levels of mean blood glucose more precisely than HbA1. These intervals can be used to estimate an individual pregnant diabetic woman's mean blood glucose from her fructosamine or HbA1 results and to verify self blood glucose monitoring data. In well-controlled diabetic pregnancy, both fructosamine and HbA1 reliably indicated trends in blood glucose but fructosamine estimated blood glucose levels more precisely.
Staphylococcal septicaemia complicating intracavernosal autoinjection therapy for impotence in a man with diabetes.
Intracavernosal injection of vasoactive drugs is a safe, effective, and commonly used treatment for impotence in diabetic men. In prospective studies infection has rarely occurred. We report a case of life-threatening Staphylococcal septicaemia complicating this treatment in a 61-year-old man with Type 2 diabetes, probably due to a combination of an unsterile technique and drug-induced priapism. Infection is a potential risk in diabetic men using intracavernosal injection therapy and those offered it should be informed of the importance of a scrupulous sterile technique and the need to seek urgent medical help for decompression if an erection persists for more than 4-6 h.
Maternal postprandial blood glucose levels influence infant birth weight in diabetic pregnancy.
Relationships between maternal glycaemia and neonatal birth weight were studied prospectively in 14 tightly controlled pregnant women with pre-existing type 1 diabetes mellitus. Maternal glycaemia throughout pregnancy was determined from daily self blood glucose (BG) monitoring with memory meters and fortnightly fructosamine (Fr) and glycated haemoglobin (HbA1) measurements. Mean non-fasting BG and mean HbA1 throughout pregnancy correlated strongly (Spearman rank) with birth weight (0.64 and 0.73 respectively), as did mean second trimester non fasting BG (0.54), HbA1 (0.7) and Fr (0.64) and mean third trimester HbA1 (0.65), whereas mean fasting BG showed no significant correlations with birth weight at any age of pregnancy. The disparity between the strong correlation of non fasting BG with birth weight and the poor correlation of fasting BG suggests that postprandial as opposed to basal glycaemia significantly influences foetal growth and neonatal size.
Effect of meal on retinal blood flow in IDDM patients.
OBJECTIVE: The effect of postprandial hyperglycemia on retinal blood flow was examined in 11 adults with insulin-dependent diabetes mellitus (IDDM) and 9 nondiabetic subjects. RESEARCH DESIGN AND METHODS: Retinal blood flow was measured with bidirectional laser Doppler velocimetry before and 60 and 120 min after a 50-g carbohydrate breakfast. Diabetic subjects were studied twice, being randomized to take their usual insulin (isoglycemic study) or to omit their morning short-acting insulin (hyperglycemic study). Nondiabetic subjects were studied once and received no insulin. RESULTS: Plasma glucose rose significantly (from 11.5 +/- 5.2 to 22.1 +/- 5.5 mM, P less than 0.001) during the hyperglycemic study but not during the isoglycemic or nondiabetic studies. There were no significant changes in blood pressure or retinal blood flow in any of the groups studied. CONCLUSIONS: Short-term hyperglycemia does not increase retinal blood flow.
Effects of high monounsaturated and polyunsaturated fat diets on plasma lipoproteins and lipid peroxidation in type 2 diabetes mellitus.
Increased free radical peroxidation of lipoproteins may contribute to the excess atherosclerosis in Type 2 diabetes mellitus and may be aggravated by increasing polyunsaturate intake. Increasing intake of monounsaturates might have similar hypolipidaemic effects while avoiding this problem. Therefore the effects of high monounsaturated and polyunsaturated fat diets on plasma lipoproteins and lipid peroxidation were compared, against each other and a relatively high saturated fat baseline diet, in 13 men with Type 2 diabetes and 12 healthy controls, randomized in crossover fashion to each diet. There were no differences in plasma lipoproteins between the monounsaturated and polyunsaturated fat diets in the diabetic and control groups separately, but when both groups were combined, high density lipoprotein cholesterol was higher on the monounsaturated fat diet (p = 0.04). Plasma lipid peroxidation was similar on the monounsaturated and polyunsaturated fat diets in both groups, but all indices of plasma lipid peroxidation in the diabetic group and lipid peroxides in the controls were significantly lower on these diets compared to the baseline diet. Both high monounsaturated and polyunsaturated fat diets increase hepatic metabolism of low density lipoprotein and shorten its circulating half-life and both may reduce lipid peroxidation, compared to high saturated fat diets, by this mechanism. On high polyunsaturated fat diets, this effect may offset any increased susceptibility of polyunsaturate enriched low density lipoprotein to peroxidation.