Biomedical subjects

M Farrer

Publications and source records attributed to M Farrer.

9 recordsLinked to original sources

PubMed1992

A simple, sensitive technique for classification of apolipoprotein(a) isoforms by sodium dodecyl sulphate-polyacrylamide gel electrophoresis.

Lipoprotein(a) (Lp(a)) is a lipoprotein containing a unique glycoprotein, apolipoprotein(a) (apo(a)), which shows considerable heterogeneity of apparent molecular mass on sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). A unifying classification of isoform has been lacking. A simple sensitive procedure for classifying apo(a) isoforms was developed in which the relative mobility of apo(a) on SDS-PAGE was related to that of apolipoprotein (apo) B-100 (Rf vs B). After Western blotting apo(a) bands were visualised by a sensitive double antibody technique employing commercial polyclonal antibodies (sheep antihuman Lp(a) antibody, alkaline phosphatase-linked donkey antisheep antibody). The technique was sensitive (lower limit of detection 0.02 micrograms apo(a)) and had good reproducibility (coefficient of variation 0.9-6.4%). Ten isoform mobilities are described (less than 0.35, 0.40, 0.50, 0.60, 0.70, 0.80, 1.0, 1.10, greater than 1.15). Individuals may have single or double band phenotypes. This classification is compatible with those previously described and the method is suitable for many laboratories, as it employs standard equipment and commercially available materials.

Apolipoproteins A↗

PubMed1992

Effect of acute inhibition of lipolysis on operation of the glucose-fatty acid cycle in hepatic cirrhosis.

Hepatic cirrhosis is frequently associated with glucose intolerance and insulin resistance, but the mechanisms underlying the insulin insensitivity are unknown. Plasma concentrations of nonesterified fatty acids (NEFA) are typically elevated in cirrhosis, and the glucose-fatty acid cycle provides a mechanism by which fatty acids may play a role in regulating glucose metabolism. We have therefore investigated the effect of acute inhibition of lipolysis, using the nicotinic acid analogue, acipimox, in 10 male patients with cirrhosis. All subjects were studied in the postabsorptive state after a 10- to 12-hour fast and were given either acipimox 250 mg or a placebo orally 2 hours before a 75-g oral glucose tolerance test (OGTT) and an infusion of insulin (50 mU/kg/h) and glucose (6 mg/kg/min) (insulin sensitivity tests [IST]). The drug was taken in a double-blind crossover design for each test. During the 2 hours following acipimox, there were rapid decreases in plasma NEFA, glycerol, and 3-hydroxybutyrate, confirming inhibition of lipolysis, while there were significant decreases in glucose, insulin, and C-peptide (P less than .001) compared with patients receiving the placebo. Acipimox blunted the increase in glucose after oral glucose loading and decreased incremental glucose concentration (from 579 +/- 76 to 445 +/- 65 mmol/min/L, P less than .02) and incremental insulin concentration (from 13.4 +/- 2.5 to 9.0 +/- 1.4 U/min/L, P = .056) in the OGTT. Improvements in classification of glucose tolerance were seen in five subjects. During the IST, significant reductions occurred in steady-state blood glucose (to 8.8 +/- 1 mmol/L, P less than .02) and C-peptide (to 3.0 +/- 0.5 nmol/L, P less than .05).(ABSTRACT TRUNCATED AT 250 WORDS)

3-Hydroxybutyric Acid↗

PubMed1992

Acute metabolic and hormonal responses to the inhibition of lipolysis in non-obese patients with non-insulin-dependent (type 2) diabetes mellitus: effects of acipimox.

1. Increased rates of fatty acid oxidation are frequently observed in patients with non-insulin-dependent diabetes mellitus and may contribute to hyperglycaemia by both decreasing peripheral glucose disposal and, more importantly, by increasing the rate of gluconeogenesis and therefore hepatic glucose output. Despite this relationship between lipid and carbohydrate metabolism, fasting glucose concentrations do not fall acutely in patients with non-insulin-dependent diabetes mellitus when plasma non-esterified fatty acid concentrations and lipid oxidation rates are decreased, questioning the importance of this interaction to glycaemic control. We have therefore measured the acute changes that occur 120-150 min after administration of 500 mg of the antilipolytic agent acipimox in eight non-obese male patients with non-insulin-dependent diabetes mellitus. 2. After administration of acipimox, lipolysis was inhibited as reflected by lower plasma non-esterified fatty acid (0.05 +/- 0.02 versus 0.55 +/- 0.05 mmol/l, P less than 0.001) and blood glycerol (8 +/- 1 versus 56 +/- 8 mumol/l, P less than 0.001) concentrations. The lipid oxidation rate was decreased (0.63 +/- 0.05 versus 1.02 +/- 0.08 mg min-1 kg-1, P less than 0.001), whereas there was a significant increase in the carbohydrate oxidation rate (1.93 +/- 0.17 versus 1.22 +/- 0.18 mg min-1 kg-1, P = 0.02).(ABSTRACT TRUNCATED AT 250 WORDS)

3-Hydroxybutyric Acid↗

PubMed1992

A double blind study of the effect of acipimox on serum lipids, blood glucose control and insulin action in non-obese patients with type 2 diabetes mellitus.

Hyperlipidaemia, in particular raised concentrations of serum triglycerides, together with raised plasma non-esterified fatty acid concentrations, is common in patients with Type 2 (non-insulin-dependent) diabetes mellitus and may be associated with insulin insensitivity. Thirty non-obese Type 2 diabetic patients (15 controlled with diet alone and 15 with diet plus oral sulphonylurea therapy) were therefore recruited to take part in a double-blind, randomized, crossover comparison of acipimox (250 mg three times daily for 3 months) and placebo. Serum lipids, blood glucose control, insulin sensitivity, and glucose tolerance were measured before and after each treatment period. There was a significant decrease in serum triglycerides (2.05 +/- 1.08 vs 2.91 +/- 1.75: p < 0.005), cholesterol (5.66 +/- 1.02 vs 6.26 +/- 1.17: p = 0.0005), and apoprotein B (1.32 +/- 0.23 vs 1.44 +/- 0.25: p < 0.05) while HDL cholesterol and apoprotein A-1 concentrations were unchanged. There was no change in blood glucose control measured by fasting glucose, insulin, and HBA, concentrations, but there was a significant improvement in insulin action assessed by glucose-insulin infusion. Although plasma non-esterified fatty acid concentrations were lower during the oral glucose tolerance test after acipimox, there was no difference in either the peak or 2-h plasma glucose concentrations and the total area under the glucose curve did not change. Acipimox was well tolerated and no patients withdrew from the study for drug-related symptoms. Thus, acipimox effectively lowers serum cholesterol and triglycerides in patients with Type 2 diabetes without adversely altering blood glucose control, and appears to improve insulin sensitivity.

Analysis of Variance↗

PubMed1992

Relation between insulinemia, body mass index, and lipoprotein composition in healthy, nondiabetic men and women.

Altered lipoprotein composition may be a better predictor of cardiovascular disease than modestly increased serum lipid concentrations, although possible interactions between lipoprotein composition, obesity, and insulinemia have not been fully elucidated. Therefore, we investigated the association between different measures of insulinemia and lipoproteins in 297 healthy Caucasian men (body mass index [BMI] less than 27 in 233, greater than 27 [obese] in 64) and 295 healthy Caucasian women (BMI less than 25 in 198, greater than 25 [obese] in 97). Associations observed in both obese and nonobese men and women were between increasing tertiles of most insulin measures and serum triglyceride concentrations (p = 0.079-0.004) and the ratio of low density lipoprotein to high density lipoprotein cholesterol (p = 0.094-0.008). Graded reductions in the high density lipoprotein cholesterol to apolipoprotein A-I ratio were also recorded in obese women, with increasing tertiles of fasting (p = 0.014-0.007) and postglucose load (p = 0.001) serum insulin levels, after correcting for BMI and triglyceride concentrations. Less marked graded increases in the triglyceride to apolipoprotein B ratios were recorded in obese women with increasing tertiles of fasting (p = 0.001-0.006) and postglucose challenge (p = 0.081) insulinemic measures. In men with normal or slightly elevated cholesterol levels (fasting serum cholesterol less than 6.5 mmol/l), hyperapobetalipoproteinemia was recorded with increasing tertiles of insulinemia (p = 0.006, correcting for BMI and triglyceride concentrations), as well as in subjects with hypertriglyceridemia (fasting serum triglycerides greater than 1.70 mmol/l) (p = 0.004, correcting for BMI and age). Hyperinsulinemia and insulin resistance are associated with altered lipoprotein composition in obese women, presumably reflecting a complex interplay between sex hormones, body mass, and insulin action. Insulin resistance appears to be more associated with apolipoprotein B concentrations in men. The hyperinsulinemic nondiabetic subject may be at increased risk of cardiovascular disease because of altered concentrations of apolipoprotein concentrations and lipoprotein composition.

Adult↗

PubMed1991

A comparison of measurements of lean body mass derived by bioelectrical impedance, skinfold thickness and total body potassium. A study in obese and non-obese normal subjects.

The measurement of body composition is an important part of metabolic and epidemiological research, but most currently available methods are complex and expensive. We have, therefore, compared measurements of fat mass (FM) and lean body mass (LBM), obtained using a commercially available bioelectrical impedance monitor (The Holtain Body Composition Monitor) (IMP), and by measuring skinfold thickness (SFT), with values obtained by measuring total body potassium (TBK). Twenty subjects, 10 with a body mass index (BMI) less than 30 (kg m-2), (non-obese) and 10 with BMI greater than or equal to 30 (obese) took part in the study. There was a strongly significant linear relationship between LBM calculated from TBK and that calculated from impedance (IMP), in both non-obese and obese groups analysed separately (non-obese: r = 0.92; p less than 0.001 and obese: r = 0.92; p less than 0.001) and together (all: r = 0.89; p less than 0.001). LBM calculated from TBK was strongly linearly correlated with values derived from SFT for non-obese (r = 0.91; p less than 0.001) but not for obese subjects. Mean values of LBM of non-obese subjects derived by each method were not significantly different (TBK: 51.3 +/- 10.40 kg; IMP: 53.18 +/- 10.37 kg; SFT: 48.87 +/- 9.48 kg), but significant differences existed when the subjects were obese (TBK: 51.86 +/- 9.65 kg; IMP: 58.69 +/- 8.55 kg; SFT: 67.61 +/- 8.14 kg; p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Anthropometry↗

PubMed1991

The association of different measures of insulinaemia with vascular risk factors in healthy normoglycaemic normotensive non-obese men and women.

Hyperinsulinaemia is said to be a risk factor for cardiovascular disease, but the extent to which different insulinaemic measures are associated with vascular risk factors in ostensibly healthy individuals, and whether they operate independently in men and women, remains uncertain. The association between risk factors and various insulinaemic measures was examined in 148 men and 118 women who were normoglycaemic, normotensive, and non-obese (body mass index in men less than 27, in women less than 25). A 75 g glucose tolerance test was administered after blood sampling for fibrinogen, lipids, lipoproteins and insulin. Insulin was also measured after 1 and 2 hours. Significant univariate correlations (p less than 0.01) were most consistently recorded between insulinaemic measures and fasting serum triglycerides in men and women, whilst systolic blood pressure only correlated with insulinaemia in women, and diastolic blood pressure correlated with fasting and 2 hour insulinaemic measures in men and women. Inconsistent associations were noted with total serum cholesterol in men and women, with high density lipoprotein cholesterol, body mass index, apoprotein B and A1 in men, and with fibrinogen in women. Age was not correlated with any insulinaemic measure in men or women. Differences in vascular risk factors between quintiles of the insulinaemic measures were examined, after correction for body mass index. The dominant association with fasting and post-glucose load insulinaemic measures was with triglycerides, especially in women, with less frequent graded differences between quintiles observed for total cholesterol, and diastolic and systolic blood pressures in men and women. The incidence of other risk factors often only differed in the lowest or highest quintile in comparison to other quintiles, suggesting a threshold rather than a graded effect. Furthermore, differences in HDL cholesterol and apoprotein B were only recorded for top quintiles of post-glucose challenge/integrated insulinaemic measures in men, whilst serum fibrinogen concentrations only differed significantly in women in the top insulinaemic area under the curve quintile. In the absence of additional risk factors such as diabetes, hypertension and obesity, insulinaemic measures are not consistently related to blood pressure and measures of lipid metabolism and coagulation, and are thus a weak predictor of other cardiovascular risk factors. The vascular risk profile associated with insulin appears somewhat different in apparently healthy men and women.

Adult↗

PubMed1990

Morning serum cortisol concentrations after 2 mg inhaled beclomethasone dipropionate in normal subjects: effect of a 750 ml spacing device.

Large spacing devices have been shown to provide more selective delivery of an inhaled steroid to the lung but the effect on the hypothalamo-pituitary-adrenal suppression associated with high dose inhaled corticosteroids has been little studied. The effect of a large spacing device (Volumatic; 750 ml) on suppression of 0900 h cortisol after 2 mg inhaled beclomethasone dipropionate was therefore investigated in normal, healthy volunteers. Twenty four subjects (12 male, 12 female) took part in a randomised, double blind, placebo controlled cross over study in which a single dose of 2 mg beclomethasone dipropionate was taken at 2300 h on two occasions seven days apart, once from a metered dose inhaler alone and once from a metered dose inhaler attached to a 750 ml spacing device. The 0900 h serum cortisol concentration was the same on the morning before each administration (468 nmol/l, 95% confidence interval (CI) 390-561 nmol/l, day 1 v 479 nmol/l, 95% CI 463-494 nmol/l, day 8). The 0900 h serum cortisol concentration the following morning, however, was lower when 2 mg beclomethasone dipropionate was given by metered dose inhaler alone (182 (95% CI 128-264) nmol/l) than when it was given by a spacing device (363 (95% CI 281-475) nmol/l). These results suggest that a large spacing device attached to a metered dose inhaler may decrease the risk of hypothalamo-pituitary-adrenal suppression by high dose inhaled steroid treatment.

Administration, Inhalation↗

PubMed1978

Health centres.

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Community Health Services↗