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Biomedical subjects

D G Johnston

Publications and source records attributed to D G Johnston.

At least 19 recordsLinked to original sources
PubMed1992

Detection of premature atherosclerosis by high-resolution ultrasonography in symptom-free hypopituitary adults.

Retrospective analysis suggests that there is increased mortality from vascular disease in hypopituitary adults, but vascular status before death is unknown. High resolution B-mode ultrasonic imaging of both carotid and femoral arteries was therefore done in 34 adult hypopituitary patients on routine replacement therapy and was compared with that in 39 matched controls. Changes were related to risk factors for vascular disease. Carotid intima-media thickness was greater in patients than in controls (mean [SD] 0.74 [0.16] vs 0.65 [0.13] mm, p < 0.02). This difference was seen in middle-aged and elderly patients. More patients than controls had one or more atheromatous plaques (65% vs 41%, p < 0.05). The percentage of individual arteries with a plaque was also higher in patients (32% vs 18%, p < 0.005). In multiple regression analysis, patients' age was the dominant factor determining carotid intima-media thickness. Symptom-free adults with hypopituitarism show an increased prevalence of atherosclerosis.

Adult↗
PubMed1992

Decrease in erythrocyte glycophorin sialic acid content is associated with increased erythrocyte aggregation in human diabetes.

1. Sialic acid moieties of erythrocyte membrane glycoproteins are the principal determinants of the negative charge on the cell surface. The resultant electrostatic repulsion between the cells reduces erythrocyte aggregation and hence the low shear rate viscosity and yield stress of blood. 2. Using g.c.-m.s., a decrease in sialic acid content has been observed in the major erythrocyte membrane glycoprotein, glycophorin A, obtained from nine diabetic patients compared with that from seven normal control subjects [median (range): 3.30 (0.01-11.90) versus 18.60 (3.20-32.60) micrograms/100 micrograms of protein, P less than 0.02]. 3. Erythrocyte aggregation, measured by viscometry as the ratio of suspension viscosity to supernatant viscosity (LS/S) in fibrinogen solution, was increased in ten diabetic patients compared with ten normal control subjects (mean +/- SEM, 37.6 +/- 1.3 versus 33.8 +/- 0.6, P less than 0.02). 4. In the patients in whom both viscometry and carbohydrate analysis were performed, the decrease in erythrocyte glycophorin sialylation and the increase in erythrocyte aggregation in fibrinogen solution were related statistically (LS/S correlated negatively with glycophorin sialic acid content, r = 0.73, P less than 0.05). 5. Decreased glycophorin sialylation provides an explanation at the molecular level for increased erythrocyte aggregation and it may be important in the pathogenesis of vascular disease in diabetes.

Adult↗
PubMed1992

Abnormalities of intermediary metabolism following a gestational diabetic pregnancy.

OBJECTIVE: The aim of this study was to compare intermediary metabolism in glucose tolerant women with previous gestational diabetes and control women without a history of gestational diabetes. SUBJECTS: Fifteen women with previous gestational diabetes and 15 controls individually matched for race, age and body mass index were included. Only subjects with normal glucose tolerance were included in this study. METHODS: Plasma glycerol, 3-OH butyrate, non-esterified fatty acids (NEFA), glucose and insulin were measured fasting and following a 75 g oral glucose load. RESULTS: The women with previous gestational diabetes and their matched controls were of similar racial origin, age and body mass index. There was no difference between those with previous gestational diabetes and controls in fasting glycerol, 3-OH butyrate, NEFA, glucose or insulin concentrations. Following the oral glucose load, glycerol, 3-OH butyrate and NEFA concentrations fell in both groups. However, compared with controls at 120 minutes, those with previous gestational diabetes had significantly higher concentrations of glycerol (median 57, range 24-216 vs 27, range 8-89 mumols/l, P less than 0.005) and 3-OH butyrate (9, range 1-18 vs 5, range 2-11 mumols/l, P less than 0.01). NEFA concentrations were similar in the two groups. Despite similar glucose concentrations during the oral glucose tolerance test the insulin response during the first 60 minutes following oral glucose was significantly reduced in the subjects with previous gestational diabetes when compared with controls (insulin area, 0-60 minutes; 2172, range 788-4767 vs 2830, range 996-4784 pmol min/l, P less than 0.05). CONCLUSIONS: Women with a previous history of gestational diabetes, despite having normal glucose tolerance, have defective insulin release with resultant abnormalities of intermediary metabolism.

3-Hydroxybutyric Acid↗
PubMed1992

Postprandial thermogenesis is reduced in polycystic ovary syndrome and is associated with increased insulin resistance.

OBJECTIVE: In order to investigate the possible causes and effects of obesity in polycystic ovary syndrome resting energy expenditure, postprandial thermogenesis and insulin resistance were measured in 14 polycystic ovary syndrome subjects and in 14 controls. DESIGN: A cross-sectional study of a selected group of patients was performed. PATIENTS: Seven of the PCOS subjects were obese and seven lean. Controls were individually matched for age, race, weight, body mass index (BMI) lean body mass and percentage fat. The obese, but not lean, polycystic ovary syndrome subjects had a greater waist:hip ratio than controls (median (range) obese PCOS 0.865 (0.823-0.960) vs obese control 0.804 (0.823-0.940), P less than 0.025). MEASUREMENTS: Metabolic rate was measured by continuous indirect calorimetry and insulin sensitivity was assessed by a short insulin tolerance test. RESULTS: The resting energy expenditure (REE) was similar in PCOS subjects and controls (median (range), 6796 (5489-7774) vs 6833 (4893-8492) kJ/day). REE correlated with LBM in the PCOS group (r = 0.83, P less than 0.00) and the control group (r = 0.82, P less than 0.001). Postprandial thermogenesis was reduced in polycystic ovary syndrome (obese: median 45.4 (range 33.6-100.0) vs 86.5 (67.2-109.2) kJ (P less than 0.05); lean: 79.4 (73.5-108.4) vs 89.9 (76.0-109.2) kJ (P less than 0.05). Fasting insulin (9.7 +/- 3.6 vs 4.4 +/- 0.8 mU/l, P less than 0.05) and postprandial incremental insulin rise (163 +/- 31 vs 116 +/- 15 mU/l, P less than 0.025) were higher in polycystic ovary syndrome. Insulin sensitivity was reduced in polycystic ovary syndrome (obese: median 136 (range 92-169) vs 173 (109-225) mumol/l/min (P less than 0.05); lean: 161 (138-225) vs 194 (161-253) mumol/l/min (P less than 0.05)). The reduction in insulin sensitivity correlated with the reduced postprandial thermogenesis in the polycystic ovary syndrome group (r = 0.75, P less than 0.01). CONCLUSION: These results confirm previous reports of hyperinsulinaemia and insulin resistance in polycystic ovary syndrome. Furthermore, polycystic ovary syndrome subjects have a reduced postprandial thermogenesis which is related statistically to the reduced insulin sensitivity. The decreased postprandial thermogenesis may predispose women with polycystic ovary syndrome to weight gain.

Adult↗
PubMed1992

The response of hepatic lipase and serum lipoproteins to acute hyperinsulinaemia in type 2 diabetes.

Hepatic lipase has a putative role in the catabolism of HDL particles and, while its activity is dependent upon insulin in the rat, no such insulin responsiveness has been demonstrated in man. We studied 21 patients with type 2 diabetes to examine whether hepatic lipase activity was influenced by hyperinsulinaemia during a 2-4 h isoglycaemic clamp study. Acute changes in lipids, lipoproteins and apolipoproteins were also documented in pre- and post-clamp serum. Hepatic lipase activity during hyperinsulinaemia was compared with activity measured after an equivalent period without insulin. For comparison, nine non-diabetic subjects (matched for age and body mass index) underwent similar clamp studies. In the control experiment without insulin, hepatic lipase activity did not change significantly (mean 9.7 (range 2.3-22.3) in the morning and 9.9 (3.0-22.5) mmol h-1 l-1 in the afternoon, NS). In contrast, after the hyperinsulinaemic clamp, hepatic lipase activity fell significantly in diabetic subjects from 12.8 (4.4-30.6) to 10.4 (3.3-31.3) mmol h-1 l-1, P less than 0.0002 along with serum triglycerides and total and LDL cholesterol. The change in hepatic lipase activity was positively related to the fasting apoprotein B concentration (Spearman r = 0.54, P = 0.016). In the normal subjects, a similar decline in hepatic lipase activity was observed during hyperinsulinaemia (from 15.1 (9.8-32.7) to 12.6 (6.3-28.3) mmol h-1 l-1, P less than 0.01) along with decreases in total, HDL and LDL cholesterol, triglycerides and apoproteins A1 and B.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Ethnic differences in insulin secretion in women at risk of future diabetes.

The plasma glucose and insulin responses to oral glucose were studied in 44 women who had previously had gestational diabetes, but had reverted to normal glucose tolerance. Twenty were White, 14 Black, and 10 Asian. A group of race-, age- and weight-matched controls was also studied. Fasting values of glucose and insulin did not differ significantly between the study group and controls. During the 2 h 75-g OGTT the White and Black previously gestational-diabetic women had similar plasma glucose values to their controls, while the Asian previously gestational-diabetic women had significantly higher glucose values at 30 min (9.2 +/- 0.6 (+/- SE) vs 7.1 +/- 0.3 mmol l-1, p less than 0.02) and at 60 min (8.6 +/- 0.8 vs 6.2 +/- 0.4 mmol l-1, p less than 0.02). Compared with their race-matched controls, the White previously gestational-diabetic women had significantly lower insulin values at 60 min (median 41 range 2-91) vs 56 (15-118) mU l-1, p less than 0.05), and the Black previously gestational-diabetic women had lower values at both 30 min (17 (4-116) vs 53 (22-197) mU l-1) and 60 min (36 (4-148) vs 99 (12-169) mU l-1, p less than 0.05). The insulin values were similar during the OGTT in the Asian previously gestational-diabetic women and their controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

High prevalence of gestational diabetes in women from ethnic minority groups.

The influence of ethnic origin, body mass index, and parity on the frequency of gestational diabetes was assessed in 11,205 consecutive women attending a multiracial antenatal clinic in London, where all women were screened for gestational diabetes. Logistic regression was used to model the relationship between gestational diabetes and ethnic origin, age, body mass index (BMI), and parity. Results were presented as adjusted odds ratios, where the reference categories are White women, age < 25 years, BMI < 27, and parity < 3. Ethnic origin was the dominant influence on the prevalence of gestational diabetes. Women from ethnic groups other than White had a higher frequency of gestational diabetes than White women (2.9% vs 0.4%, p < 0.001). Compared to White women the relative risk of gestational diabetes in the other ethnic groups was: Black 3.1 (95% confidence limits 1.8-5.5), South East Asian 7.6 (4.1-14.1), Indian 11.3 (6.8-18.8), and miscellaneous 5.9 (3.5-9.9). Increasing age was an independent risk factor. The relative risk was higher in women > or = 35 years in all ethnic groups other than in South East Asian women. Obesity (BMI > or = 27) was a further independent risk factor in all ethnic groups except in the Indian and South East Asian women. Parity > or = 3 increased the relative risk of gestational diabetes in the White, Black, and South East Asian women only.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1992

Myocardial dysfunction in treated adult hypopituitarism: a possible explanation for increased cardiovascular mortality.

OBJECTIVE: To assess cardiac structure and function in patients with treated hypopituitarism and to determine their relation to the degree of growth hormone deficiency and body composition pattern. DESIGN: 26 patients with treated hypopituitarism were studied by cross sectional and Doppler echocardiography and by exercise testing. The results were analysed and their relation to the degree of growth hormone deficiency and body composition determined. SETTING: All tests were performed in the department of cardiology and the unit of metabolic medicine at a tertiary referral centre. PATIENTS: Patients with hypopituitarism referred for endocrine assessment. MAIN OUTCOME MEASURES: Left ventricular mass, left ventricular diastolic function, and exercise capacity in patients with hypopituitarism and their relation to growth hormone deficiency. RESULTS: Mean (SD) serum concentration of insulin-like growth factor 1 (IGE-1), a measure of growth hormone deficiency, was 82.4 (45) micrograms/l. Lean body mass calculated by measuring total body potassium was 50 (9) kg. All patients had a normal left ventricular mass index and a normal left ventricular ejection fraction. Eight patients had abnormal left ventricular diastolic function. There was a significant correlation between IGF-1 and left ventricular mass (r = 0.45, p less than 0.02). Lean body mass was also significantly correlated with left ventricular mass (r = 0.78, p less than 0.0001) and left ventricular diastolic function (r = -0.63, p less than 0.01). The mean exercise duration was 8.6 (3.6) minutes. There was a significant correlation between serum IGF-1 and the rate-pressure product on exercise (r = 0.47, p less than 0.01). Seven patients had planar ST segment depression greater than 0.1 mV during exercise testing. In five of these patients there was rapid resolution of ST segment depression immediately after exercise. Two patients developed considerable ST segment depression, and subsequent coronary angiography showed normal coronary arteries. Exercise-induced ST segment depression was not related to the severity or duration of growth hormone deficiency or serum cholesterol concentration. CONCLUSIONS: This study suggests that left ventricular mass and the rate-pressure product are related to the degree of growth hormone deficiency, that left ventricular diastolic dysfunction is frequently seen in hypopituitarism, and that these patients may have ischaemic-like ST segment changes during exercise testing. These findings may explain the increased cardiovascular mortality in patients with hypopituitarism and may also have implications for growth hormone replacement therapy in adults.

Adult↗
PubMed1992

Metabolic changes and vascular risk factors in hypopituitarism.

Adults with hypopituitarism die prematurely, and the excess mortality is from vascular disease. On echocardiography we have demonstrated abnormalities of myocardial diastolic function in hypopituitary adults, indicating possible early ischaemic change. Peripheral arterial disease is evident on ultrasonography. Vascular risk factors have also been examined. Impaired glucose tolerance and unrecognized diabetes are common in hypopituitary adults. Total cholesterol levels are elevated, particularly in hypopituitary women. The role of growth hormone (GH) deficiency in the vascular disease and in the vascular-risk-factor abnormalities is unknown at present. Prolonged GH therapy causes a decrease in the levels of fasting total cholesterol, without any adverse effects on glucose homeostasis. GH therapy trials in adults will clarify the role of GH in the excess vascular risk of hypopituitarism. Prolonged GH therapy will be necessary for the vascular effects to be defined.

Adult↗
PubMed1992

Preparation and characterization of an antibody specific to the rat dopamine D2 receptor.

Antibodies specific to the dopamine D2 receptor have been raised in rabbits using synthetic peptides. The resulting antiserum was sensitive to picogram quantities of peptide as measured by enzyme-linked immunoassay and was shown to have a 33% cross-reactivity with partially purified D2 receptor protein. No detectable cross-reactivity with similarly prepared fungal membranes was observed. D2 receptor preparations from normal rat pituitary cells were used in Western blot analysis. Bands of M(r) = 95,000 and 34,000 were detected in these preparations with a third faint band at 120,000. These correspond to the pituitary D2 receptor.

Animals↗
PubMed1991

A defect in insulin release in women at risk of future non-insulin-dependent diabetes.

1. A study on seven Caucasian glucose-tolerant women with previous gestational diabetes and seven matched control subjects is presented. The insulin response to oral glucose, insulin sensitivity and fasting glucose production rates were measured by using a 75 g oral glucose tolerance test, an insulin tolerance test and a non-radioactive tracer, [6,6-2H]glucose, respectively. 2. Fasting plasma glucose levels were similar between the women with previous gestational diabetes and the control subjects (4.8 +/- 0.3 versus 4.7 +/- 0.2 mmol/l), as were fasting plasma insulin levels (median 4 m-units/l, range 1-13 m-units/l versus median 4 m-units/l, range 1-24 m-units/l). After oral glucose the 60 min plasma glucose levels in the women with previous gestational diabetes were significantly higher (8.5 +/- 0.6 versus 6.7 +/- 0.8 mmol/l, P less than 0.05), whereas the plasma insulin level was significantly lower at both 30 min (median 23 m-units/l, range 4-47 m-units/l versus median 55 m-units/l, range 23-100 m-units/l, P less than 0.02) and at 60 min (median 23 m-units/l, range 4-43 m-units/l versus median 60 m-units/l, range 16-126 m-units/l, P less than 0.02). 3. Insulin sensitivity, expressed as the slope of the regression line of plasma glucose level against time after intravenous infusion of insulin (0.05 unit/kg), was similar in the women with previous gestational diabetes and the control subjects (mean slope, -0.17 +/- 0.01 versus -0.17 +/- 0.01). 4. Fasting glucose production rates were similar in the women with previous gestational diabetes and the control subjects (2.2 +/- 0.3 versus 1.9 +/- 0.1 mg min-1 kg-1).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Feedback inhibition of insulin secretion in type 2 diabetes.

1. The purpose of the present study was to examine the ability of insulin to inhibit its own secretion in type 2 diabetes independently of the prevailing plasma glucose concentration. 2. The responses of the plasma C-peptide concentration to sustained hyperinsulinaemia were assessed during a 200 min isoglycaemic clamp study in 14 patients with type 2 diabetes and seven age- and weight-matched control subjects. The arterialized venous plasma glucose concentration was clamped at approximately 0.3 mmol/l below each subject's own basal level and was not permitted to rise above the basal level. 3. In the fasting state, the plasma C-peptide concentration was slightly, but not significantly, higher in the diabetic patients than in the control subjects (667 versus 413 pmol/l, respectively, P = 0.07), but it remained significantly higher in the diabetic patients during the clamp studies in absolute terms (minimum plasma C-peptide concentration 400 pmol/l in diabetic patients versus 151 pmol/l in control subjects, P less than 0.05) and was suppressed to a lesser extent when expressed as a percentage change from basal (35.8% in diabetic patients versus 59.4% in control subjects, P less than 0.01). 4. In order to investigate whether a high plasma glucose concentration was maintaining the plasma C-peptide concentration in the diabetic patients, six of these patients underwent a second clamp study at euglycaemia (plasma glucose concentration 5.2 mmol/l). Under these conditions, the plasma C-peptide concentration was suppressed to the same extent as in the control subjects (from 623 to 195 pmol/l, a change of 62.7%).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Metabolic effects of pharmacological adrenergic blockade in phaeochromocytoma.

Twelve-hour hormonal and metabolic profiles were performed in a 68-year-old woman with a benign adrenal phaeochromocytoma (a) prior to adrenergic blockade, (b) after the establishment of pharmacological alpha-blockade with phenoxybenzamine, (c) after combined alpha and beta-blockade with phenoxybenzamine and propranolol, and (d) after successful surgery and withdrawal of medication. Pretreatment, (a) vs (d), significant elevations (12-h mean +/- SD) were observed in the concentrations of noradrenaline (44.9 +/- 14.4 vs 2.3 +/- 0.7 nmol/l, P less than 0.01), glucose (6.9 +/- 1.9 vs 5.0 +/- 1.0 mmol/l, P less than 0.05), glycerol (0.22 +/- 0.02 vs 0.07 +/- 0.01 mmol/l, P less than 0.01), non-esterified fatty acids (0.71 +/- 0.28 vs 0.34 +/- 0.08 mmol/l, P less than 0.01), and total ketone bodies (0.08 +/- 0.03 vs 0.03 +/- 0.02 mmol/l, P less than 0.01). Alpha-blockade, (b) vs (a), was associated with an increase in noradrenaline levels (P less than 0.01) but not with any significant alterations in intermediary metabolite concentrations. Following the establishment of combined alpha and beta-blockade, (c) vs (b), plasma noradrenaline returned to its pretreatment level while the concentrations of glycerol, fatty acids and ketone bodies were normalized. A completely physiological 12-h blood glucose profile, however, was observed only post-operatively. No significant differences were observed in mean plasma insulin levels between the four studies. These results indicate impaired regulation of multiple aspects of carbohydrate, lipid and ketone body metabolism in our patient.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenal Gland Neoplasms↗
PubMed1991

Abnormalities in fasting circulating proinsulin concentration in mild gestational diabetes.

Fasting plasma proinsulin, insulin and glucose concentrations were measured in ten women with mild gestational diabetes and ten controls matched for race, age (32 +/- 6 vs 31 +/- 6 years), body mass index (28 +/- 8 vs 27 +/- 6) and gestational week (24 +/- 4 vs 25 +/- 4 weeks). There was no significant difference in fasting plasma glucose between these gestational diabetics and their controls (median 4.7, range 3.7-6.0 mmol/l vs 4.5, range 3.4-5.3 mmol/l). The fasting proinsulin levels were significantly higher in the gestational diabetics compared with the controls (median 12.2, range less than 4-14.8 pmol/l vs 5.8, range less than 4-12.8 pmol/l, P less than or equal to 0.02, Wilcoxon Summed Rank Test), while the calculated intact insulin levels (immunoreactive insulin minus proinsulin) were significantly lower (median 14.5, range 6.3-81.8 pmol/l vs 51.6, range 11.7-312 pmol/l, P less than or equal to 0.01). The ratio of proinsulin to calculated intact insulin was significantly higher in the gestational diabetics than the controls (median 0.66, range 0.16-2.04 vs 0.12, range 0.03-0.62), P less than or equal to 0.01). These results demonstrate that gestational diabetics, with normal fasting plasma glucose values, have abnormalities in pancreatic beta-cell secretion, which are likely to be important both in the aetiology of gestational diabetes and non-insulin dependent diabetes.

Adult↗
PubMed1991

Dopamine, the dopamine D2 receptor and pituitary tumours.

Dopamine plays an important role in the hypothalamic-pituitary axis where its major effects are to inhibit pituitary hormone secretion and cell division. Chronic dopamine deficiency has been postulated as a cause of pituitary tumour formation and several lines of evidence exist to suggest that a functional deficiency may develop as a result of defective dopamine receptor action. The available data suggest that a number of sites in the dopamine-D2 receptor-second messenger pathways may be implicated. These abnormalities are reflected in the variety of responses to dopamine and its agonists which have been observed in pituitary tumours both in the clinical situation and in cultured cells in vitro. Whilst it seems likely that the primary defect in pituitary tumour formation lies within the pituitary itself, the role of hypothalamic factors in facilitating tumour growth remains to be explored. Further studies of the dopamine receptor and its function will be of value not only in pathophysiological studies of human pituitary adenomas, but also in the development of new pharmacological agents to treat patients with these tumours.

Dopamine↗
PubMed1991

Correlation of plasma insulin and insulin-like growth factor-I with indices of androgen transport and metabolism in women with polycystic ovary syndrome.

OBJECTIVE: Polycystic ovary syndrome (PCOS) is said to be associated with hyperinsulinaemia. Insulin stimulates androgen production by ovarian tissue in vitro and previous studies have identified a positive correlation of insulin with androstenedione. The aim of the present study was to discover whether insulin levels correlate with clinical presentation and with markers of androgen transport and metabolism in women with PCOS. DESIGN: Within-group analysis of clinical and biochemical characteristics of a consecutive series of women with PCOS, focusing on correlations of plasma insulin with clinical presentation and androgens. Insulin levels were also compared with a control group of normal women. PATIENTS: Forty-seven women who presented with hirsutism, cycle abnormalities or both, with ultrasound proven PCOS, were recruited. Mean age was 26.6 +/- 0.7 years (mean +/- SEM), BMI 27.3 +/- 1.2 kg/m2. MEASUREMENTS: Plasma insulin levels were measured at 30-minute intervals for 3 hours following a 75 g glucose load. Blood was also taken for measurement of testosterone (T), androstenedione (A), free testosterone (fT), sex hormone binding globulin (SHBG) and insulin-like growth factor-I (IGF-I). Androsterone glucoronide (AG), a marker of peripheral androgen metabolism, was also measured. RESULTS: Neither basal insulin nor the sum of insulin measurements during the glucose tolerance test (sumINS) in women with PCOS were significantly different from a control group with normal ovaries. Within the PCOS group, basal insulin was greater in women with irregular cycles or amenorrhoea than in those with regular ovulatory menses (8.0 +/- 1.1 vs 3.1 +/- 1.5 mU/l, P less than 0.01) despite similarly raised androgen levels. Both basal insulin and sumINS correlated with BMI in women with PCO (r = 0.37, P less than 0.05 and r = 0.64, P less than 0.01 respectively) but not in controls. There was no significant correlation between insulin or IGF-I levels and T, A or AG despite a positive correlation of AG (but no other androgen) with BMI. SHBG showed an inverse correlation and fT correlated positively with sumINS (r = -0.51, P less than 0.01; r = 0.39, P less than 0.05). Regression analysis of each of the androgens on the other variables demonstrated no significant relationship between insulin and androgens. CONCLUSIONS: These data suggest that, in vivo, the major effect of insulin on androgen secretion is mediated by changes in SHBG rather than by direct stimulation of ovarian androgen production. Higher insulin concentrations in anovulatory compared with ovulatory women with hyperandrogenaemia may indicate that insulin resistance in the ovary contributes to the mechanism of anovulation in PCOS.

Adult↗
PubMed1991

The effect of subcutaneous injection site on absorption of human growth hormone: abdomen versus thigh.

OBJECTIVES: To investigate whether growth hormone (GH) absorption is site dependent. DESIGN AND MEASUREMENTS: Human growth hormone (hGH, Norditropin) 4 IU, was injected subcutaneously on two separate occasions: into the thigh on one occasion and into the abdomen on a second occasion. Blood was sampled for GH, insulin, glucose, non-esterified fatty acids and glycerol at baseline and hourly for 12 hours. Serum insulin-like growth factor I was measured at baseline, and after 12 and 24 hours. SUBJECTS: Eleven healthy young adults (8 M, 3 F). RESULTS: Following the injection serum GH had risen by 1 hour and peaked by 3-6 hours. The peak GH and growth hormone area under the curve were significantly higher after injection in the abdomen compared with the thigh (GH peak (mean +/- SEM) 103 +/- 20 vs 41 +/- 8 mU/l, P = 0.002 and GH area 528 +/- 86 vs 239 +/- 34 mU/l h, P = 0.003 respectively). Serum insulin-like growth factor I at 12 and at 24 hours showed a significant rise from the baseline level, but no significant difference was observed between the two injection sites. No significant difference in plasma insulin, glucose, non-esterified fatty acids or glycerol was observed between the two methods of injection. CONCLUSION: Subcutaneously injected GH is better absorbed from the abdominal site than from the thigh.

Abdomen↗