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Biomedical subjects

D B Dunger

Publications and source records attributed to D B Dunger.

At least 145 records · Page 8Linked to original sources

Familial glucocorticoid deficiency with achalasia of the cardia associated with mixed neuropathy, long-tract degeneration and mild dementia.

This paper describes the progress of two previously reported brothers with familial glucocorticoid deficiency, achalasia of the cardia, and alacrima. In their early 'teens both boys developed polyneuropathy with sensory, motor and autonomic components, Parkinsonism, and signs of both dorsal column and pyramidal tract damage. The older boy also showed signs of dementia. Red cell folate levels were markedly reduced but plasma and CSF folate were normal. Serum B12 and erythrocyte concentrations were at or below the lower limit of normal CSF levels of homovanillic acid and 5-hydroxyindole acetic acid (the major metabolites of dopamine and serotonin in brain) were low, indicating impaired turnover of the two amines within the nervous system. Positron emission photometry scans in the older boy showed low binding of c-methyl-spiperone and reduced uptake of 18-F-L-fluorodopa in the striatum, confirming the impairment in dopamine metabolism and suggesting both reduced synthesis and reduced receptor density. Treatment with L-dopa up to 800 mg/day (along with carbidopa 200 mg/day) corrected the low CSF homovanillic acid levels and produced some improvement in the Parkinsonism but no other obvious clinical benefit. Empirical treatment with hydroxycobalamin (1000 micrograms three times a week) and folinic acid (15 mg/day) was without clinical effect. The cause of the neurological disorder, low red-cell folate concentrations, and amine disturbance remains unknown, as does the pathogenesis of the adrenocortical failure.

Adolescent↗

Half-life of exogenous growth hormone following suppression of endogenous growth hormone secretion with somatostatin in type I (insulin-dependent) diabetes mellitus.

OBJECTIVE: To estimate the half-life of growth hormone in young adult patients with type I (insulin-dependent) diabetes mellitus following bolus injection and prolonged exposure for the purpose of deconvolution analysis of plasma growth hormone profiles to determine growth hormone secretory rates. DESIGN: In the bolus study, an intravenous bolus injection of 100 mU of biosynthetic human growth hormone was given while endogenous growth hormone was suppressed by a continuous infusion of somatostatin under three different glucose clamp conditions: normoglycaemia (5 mmol/l) with normoinsulinaemia (65 pmol/l); hyperglycaemia (12 mmol/l) with normoinsulinaemia; and normoglycaemia with hyperinsulinaemia (360 pmol/l). In the infusion study, the effect of prolonged and repeated growth hormone exposure upon the growth hormone half-life was estimated. Three pulses of 60 minutes growth hormone infusion (6 mU/kg/pulse) two hours apart under euglycaemic somatostatin suppression were applied. PATIENTS: Six young adult patients with type I (insulin-dependent) diabetes mellitus were studied in both the bolus and the infusion study. RESULTS: Mean GH half-lives by mono-exponential analysis were not significantly different remaining unaltered by the short-term metabolic changes of hyperglycaemia and hyperinsulinaemia. Data were therefore pooled yielding an overall mean GH half-life of 13.6 minutes (range 11.9-19.4). Applying a bi-exponential model mean GH half-lives were 3.1 minutes (range 2.5-5.9) for the rapid phase of distribution of the hormone and 13.8 minutes (range 9.6-16.9) for the decay of GH from the circulation. The GH half-life during the infusions studies did not vary with repeated exposure but was significantly longer (mean half-life of 25.7 minutes; range 19.4-37.1) than during the bolus studies (P less than 0.001). CONCLUSIONS: The half-life of exogenous r-hGH is not affected by glucose or insulin concentrations but increases after prolonged GH exposure in young adults with type I (insulin-dependent) diabetes mellitus.

Adolescent↗

Sex hormone binding globulin levels in adolescent subjects with diabetes mellitus.

In normal adolescents there is a pubertal fall in circulating levels of sex hormone binding globulin (SHBG) in both sexes which is not explained by classically accepted mechanisms of control of SHBG. Recent in vitro and in vivo evidence has suggested that SHBG is inversely regulated by insulin. In view of this we have compared SHBG levels in 80 adolescent subjects with Type 1 diabetes to those in 61 normal adolescents. In both normals and in Type 1 diabetic subjects there was a pubertal fall in SHBG levels. Contrary to expectations, SHBG levels were not elevated in those with diabetes, but prepubertally were significantly lower in both sexes (boys mean +/- SD, 70 +/- 28 nmol l-1, normals 130 +/- 52 nmol l-1, p less than 0.001; girls, 61 +/- 17 nmol l-1, normals 110 +/- 23 nmol l-1, p = 0.01). In pubertal subjects no differences in SHBG levels were seen between the two groups, or between either sex within any group. In subjects with Type 1 diabetes SHBG levels were unrelated to metabolic control as reflected by HbA1 but were inversely related to pubertal stage (r = 0.55, p less than 0.001). In prepubertal subjects with diabetes, in whom abnormal SHBG levels were found, these levels were weakly related to insulin dose (r = 0.33, p less than 0.05); no such relationship was found in the other groups. The significance of the abnormal SHBG levels in prepubertal children with diabetes and its relationship to any irregularities of their sexual development is unclear.

Adolescent↗

Plasma and cerebrospinal fluid arginine vasopressin in patients with and without fever.

Hyponatraemia has been described in association with a number of acute infectious diseases, mainly bacterial and tuberculous meningitis and pneumonia, and has been attributed to inappropriate secretion of arginine vasopressin (AVP). The mechanism of inappropriate AVP production is uncertain, but there is experimental evidence to suggest that fever may stimulate secretion of AVP into plasma and cerebrospinal fluid. In this study, AVP concentrations in plasma and cerebrospinal fluid from 37 febrile children with infections have been compared with those from 27 afebrile control subjects. Ten of the febrile children had meningitis (eight bacterial, two viral) and the remainder a variety of other infectious diseases. Seventy four per cent of febrile infected children were hyponatraemic (serum sodium less than 135 mmol/l) compared with only 8% of the afebrile controls. Plasma AVP concentrations were significantly higher in the febrile patients (median 2.92 pmol/l, range 1.0-23.25, n = 28) than in controls (median 1.67 pmol/l, range 0.57-6.0, n = 14) but there was no significant difference in cerebrospinal fluid AVP concentrations. There was no difference in plasma AVP concentrations between patients with meningitis and those with infections not involving the central nervous system. Careful attention should be paid to fluid and electrolyte balance in all children with acute infections.

Adolescent↗

Insulin and growth factors adaptation to normal puberty.

Insulin and IGF-1 production were measured throughout childhood and puberty and into adult life. Basal insulin and IGF-1 secretion increased during puberty, falling back to prepubertal levels in adulthood. However, fasting glucose levels remained constant, implying an increase in tissue resistance to insulin coinciding with puberty.

Adaptation, Physiological↗

Diabetes insipidus. Current treatment recommendations.

Cranial diabetes insipidus (DI) arises when release of arginine vasopressin (AVP, antidiuretic hormone) in response to osmotic stimuli is inadequate. The correct diagnosis and management of cranial DI is particularly important when it arises as an acute complication of surgery, trauma or in subjects who lack thirst sensation. Desmopressin (1-desamino-8-D-arginine-vasopressin, DDAVP) provides an effective and convenient replacement therapy when given by the intranasal route. However, nasal administration is difficult for some patients, and in the future oral or transcutaneous desmopressin formulations may prove to be satisfactory alternatives. By contrast, treatments for nephrogenic DI, where there is failure of the antidiuretic response to endogenous or exogenous vasopressin, have been disappointing and water replacement remains the mainstay of therapy. An understanding of the physiology and pathophysiology of water homeostasis and correct interpretation of water balance and electrolyte data are essential for correct diagnosis and management of all cases of DI.

Arginine Vasopressin↗

Impact of increased growth hormone secretion on carbohydrate metabolism in adolescents with diabetes.

Growth hormone (GH) and fasting insulin concentrations rise during puberty in normal subjects. Any increase in GH secretion in adolescents with insulin-dependent diabetes mellitus (IDDM) might be expected to lead to further insulin resistance and metabolic disturbance. Despite the high incidence of delayed growth in IDDM, the relationship between GH, insulin-like growth factor I (IGF-I) and IGF binding protein 1 (IGFBP-1) has not been clearly established. Twenty-six adolescents with IDDM and 34 healthy siblings underwent measurement of their overnight GH secretory profiles (20.00-08.00 hours, 15-minute sampling). The diabetic subjects were studied either on their normal insulin regimen (n = 15) or during a euglycaemic clamp (n = 26). A second clamp study was undertaken (n = 7) with addition of pirenzepine to suppress GH secretion. GH profiles in the diabetic subjects were characterized by increases in both pulse amplitude and baseline GH concentrations. Deconvolution analysis also revealed an increase in the frequency of GH secretory episodes. In the subjects with diabetes, a direct link between the dawn rise in insulin requirements, increased concentrations of beta-hydroxybutyrate and the elevated concentrations of GH was established. These abnormalities were reversed by the suppression of GH pulse amplitude following pirenzepine. Serum IGF-I concentrations and IGF-I bioactivity in the diabetic subjects were low and were positively correlated with mean GH concentrations. In conclusion, well controlled adolescents with IDDM show persisting abnormalities of GH, beta-hydroxybutyrate and IGF-I despite normoglycaemia. The role of inappropriate insulin delivery in the development of these abnormalities is discussed.

3-Hydroxybutyric Acid↗

Pattern of secretion of bioactive and immunoreactive gonadotrophins in normal pubertal children.

OBJECTIVE: The aim was to investigate the relationship between the nocturnal pulsatile secretory patterns of immunoreactive and bioactive luteinizing hormone in normal children at various stages of puberty. DESIGN: Blood samples were taken at 15-minute intervals from 2000 hours to 0800 hours. Pubertal stage was assessed by the method of Tanner (1962). PATIENTS: Thirty-four healthy siblings (17 males, 17 females) of diabetic children were recruited (median age 13.1, range 9.1-20.9 years). They were of normal height, non-obese, and covered the range of puberty. MEASUREMENTS: Follicle stimulating and luteinizing hormone levels were measured by radioimmunoassay in all 34 subjects; bioactive LH (B-LH) was assayed in a subgroup of 13 subjects selected to encompass the range of normal puberty. Oestradiol (girls) and testosterone (boys) were also measured at hourly intervals. RESULTS: Immunoreactive luteinizing and follicle stimulating hormone concentrations showed a progressive rise during puberty in both sexes. FSH concentrations were significantly higher in females than in males at all stages of puberty. Overnight mean bioactive luteinizing hormone concentrations were higher than immunoreactive luteinizing hormone levels in all the girls studied (n = 7). Although the number of bioactive luteinizing hormone pulses (31) was greater than immunoreactive pulses (27), the profiles were generally very similar. In the early pubertal girls an increase in the bioactive: immunoreactive ratio was observed during the middle of the night with the onset of pulsatility. Oestrogen was detected in the girls in breast stage 4-5 but not in two of the early pubertal girls, despite pulses of immunoreactive and bioactive luteinizing hormone. The boys had higher mean bioactive than immunoreactive luteinizing hormone levels and overall bioactive and immunoreactive luteinizing hormone and testosterone concentrations increased with puberty stage. Concordance between bioactive and immunoreactive hormone pulses was good although more immunoreactive pulses (16) were seen than bioactive pulses (14). As in the girls, an increase in the bioactive: immunoreactive ratio was observed in the middle of the night with the onset of pulsatility at genital stage 2 but, in contrast to the oestrogen data in the girls, testosterone secretion always followed luteinizing hormone pulsatility overnight. CONCLUSION: We conclude that mean overnight immunoreactive luteinizing and follicle stimulating hormone concentrations increase during puberty in both sexes. Bioactive luteinizing hormone levels are two to three times higher than immunoreactive luteinizing hormone in both sexes, but there is very little discordance between immunoreactive and bioactive luteinizing hormone pulsatility. The bioactive: immunoreactive ratio increases with the occurrence of pulsatility overnight in early pubertal children. The relationship between these changes in bioactive and immunoreactive luteinizing hormone and sex steroids is clearest in boys where the nocturnal testosterone rise always follows pulsatile LH secretion.

Adolescent↗

Urinary growth hormone excretion during puberty in type 1 (insulin-dependent) diabetes mellitus.

The excretion of urinary growth hormone was measured by a highly sensitive direct immunoradiometric assay in a cross-sectional study during puberty in 70 children with Type 1 (insulin-dependent) diabetes mellitus and 94 normal children. In normal children (n = 24) and diabetic children (n = 17) overnight urinary growth hormone excretion correlated significantly with the mean overnight plasma concentration (r = 0.70, p less than 0.001, and r = 0.70, p less than 0.001), indicating that urinary GH excretion reflects the circulating endogenous GH level. Overnight urinary growth hormone excretion increased during puberty. In normal and in diabetic children there was a peak in boys at genital stage 4 (both p less than 0.01), and in girls at breast stage 2 (both p less than 0.02). The diabetic children excreted more urinary growth hormone than the normal children at every pubertal stage. Excretion of albumin, retinol binding protein and N-acetyl-beta-D-glucosaminidase was measured in urine from 38 diabetic children. Urinary growth hormone correlated weakly with urinary albumin (r = 0.49, p less than 0.01), retinol binding protein (r = 0.42, p less than 0.01), and N-acetyl-beta-D-glucosaminidase (r = 0.43, p less than 0.01). Urinary GH excretion was not related to blood glucose control (HbA1) in boys (n = 31) or girls (n = 39). The measurement of urinary growth hormone provides an assessment of endogenous growth hormone during puberty in normal and diabetic children. However, caution must be exercised in interpreting urinary growth hormone data from diabetic patients with increased excretion of albumin and retinol binding protein.

Acetylglucosaminidase↗

Siblings of children with diabetes: involvement, understanding and adaptation.

The psychosocial adjustment of 30 siblings (aged 8-18 years) of children with diabetes mellitus was studied. Although most were younger than the diabetic child, 55% were closely involved in the dietary management and insulin treatment of the diabetes, yet many had only a limited understanding of the disease. Most were well-adjusted. However, low levels of self-esteem were apparent among some subjects, who did not fee free to question their parents about diabetes (30%), who identified themselves as the member of the family most likely to receive blame (33%), and who reported spending more time at home with their families than their peers (40%). Nine children (30%) worried about becoming ill themselves. None believed that having a child with diabetes in the family had impaired relationships in the home. Six siblings (20%) also described some positive effects of the illness, particularly enhanced family closeness.

Adaptation, Psychological↗

Noonan's syndrome: abnormalities of the growth hormone/IGF-I axis and the response to treatment with human biosynthetic growth hormone.

Auxological and endocrine data from 6 children (3 male, 3 female) aged 8.5-12.8 years with Noonan's syndrome and the results of treatment with human biosynthetic growth hormone (hGH) are presented. All the children were short (Ht SDS -3.5 to -2.3) and height velocity SDS ranged between -1.76 and +0.03. The maximum plasma growth hormone (GH) response to standard provocation tests ranged from 17 to 52 mU/l, yet, plasma insulin-like growth factor I (IGF-I) concentrations were low or low normal. Overnight GH secretory profiles were normal in all but 2 children who had disordered pulsatility with high trough concentrations. In 5 children who have completed one year of hGH therapy mean height velocity increased from 4.8 to 7.4 cm/year and the height velocity SDS ranged from +0.2 to +3.75. This improvement was associated with an increase in plasma IGF-I in three subjects. These results suggest that a defect of the GH/IGF-I axis may be present in some children with Noonan's syndrome and hGH therapy may have a role in the management of the short stature in these children.

Age Determination by Skeleton↗

Evidence for temporal coupling of growth hormone, prolactin, LH and FSH pulsatility overnight during normal puberty.

The patterns of secretion of GH, LH, FSH and prolactin were determined over a single night (20.00-08.00 h; 15-min sampling) in 34 normal subjects (17 male, 17 female, aged 9.1-20.9 years). Plasma GH was measured by an immunoradiometric assay and LH, FSH and prolactin by radioimmunoassay in all samples. Data were analysed by Fourier transformation and cross-correlation after stationarization. The highest mean GH levels were noted in girls at Tanner stage 2/3 and in boys at stages 4/5. Prolactin levels were highest in girls at stage 4/5 and in boys at stage 2/3. LH and FSH showed a progressive rise by puberty stage in both sexes. The dominant pulse periodicities of GH and prolactin were 150-180 min in girls and 180 min in boys. LH and FSH pulse periodicity was around 90 min in early puberty and 180 min in later puberty in both sexes. LH and prolactin pulses showed a phase relationship with GH with a lag of 30-75 min (r = 0.32; P less than 0.001) and 30 min (r = 0.47; P less than 0.0001) respectively. Generally, LH and prolactin pulses were in phase (r = 0.42; P less than 0.0001) and there was a highly significant correlation (r = 0.64; P less than 0.0001) between FSH and LH pulsatility. Whereas mean overnight concentrations and pulse periodicity of the principal pituitary hormones varied between the sexes during early puberty, by the end of puberty a dominant pulse periodicity of around 150-180 min was established and there was remarkable temporal coupling of pulsatility.

Adolescent↗

Vasopressin antagonist in early postoperative diabetes insipidus.

23 patients without diabetes insipidus before transfrontal (hypothalamic) or trans-sphenoidal (pituitary) surgery were studied prospectively to investigate the pathogenesis of early postoperative diabetes insipidus. 12 patients who underwent trans-sphenoidal surgery and who did not develop diabetes insipidus were used as controls. All received prophylactic corticosteroid replacement. Blood samples were obtained immediately after operation, at the onset of diabetes insipidus, and 24 h later. Immediately after trans-sphenoidal pituitary surgery, plasma vasopressin (AVP) was raised but had fallen to subnormal concentrations by the onset of diabetes insipidus. After transfrontal hypothalamic surgery diabetes insipidus occurred sooner and was associated with high plasma AVP immunoreactivity--but the plasma showed no antidiuretic bioactivity and greatly attenuated the antidiuretic response to standard AVP. Early diabetes insipidus after hypothalamic surgery is associated with release of a substance, presumably an analogue, from the damaged hypothalamo-neurohypophyseal system, which acts as an antagonist to normal AVP activity; after trans-sphenoidal operations diabetes insipidus seems to be caused by failure of AVP release.

Adolescent↗

The growth hormone releasing hormone (GHRH) response to a mixed meal is blunted in young adults with insulin-dependent diabetes mellitus whereas the somatostatin response is normal.

Following a standard mixed meal, plasma concentrations of growth hormone releasing hormone (GHRH), somatostatin (SMS) and growth hormone (GH) were measured every 30 min for 300 min in six young adults with type I insulin-dependent diabetes mellitus (IDDM) and five normal controls. Mean blood glucose concentrations were higher and mean free insulin levels lower in the diabetics compared with controls both in fasting specimens and at all times following the mixed meal. Basal concentrations (mean +/- SEM) of GHRH were similar in diabetic (12.7 +/- 1.8 pg/ml) and control subjects (11.8 +/- 1.1 pg/ml). Following ingestion of the mixed meal, a rise in GHRH was observed in the control subjects maximal between 30 and 240 min (P less than 0.025) but the response was blunted in the diabetics. Mean GHRH concentrations were greater in the controls than in the diabetic subjects at all stages during the test, the maximum difference being noted at 120 mins (P less than 0.04). Basal SMS concentrations and those observed after the mixed meal were similar in diabetic and control subjects. These results indicate that glucose and insulin may play a role in the regulation of GHRH release following a mixed meal but circulating levels of GHRH and SMS are unlikely to be relevant to the abnormal regulation of GH in IDDM.

Adolescent↗

The growth hormone independent insulin-like growth factor-I binding protein BP-28 is associated with serum insulin-like growth factor-I inhibitory bioactivity in adolescent insulin-dependent diabetics.

The relationship between the growth hormone independent insulin-like growth factor binding protein (BP-28) and serum insulin-like growth factor-I (IGF-I) inhibitory bioactivity observed in diabetic serum was investigated in five poorly controlled adolescent type I diabetics. We have measured the in-vitro effects of purified BP-28 from amniotic fluid on serum IGF-I stimulated and basal cartilage sulphation and compared serum IGF-I bioactivity obtained from 24-h serum profiles from each diabetic subject with serum concentrations of BP-28 and IGF-I measured by specific radioimmunoassays. Purified BP-28 inhibited serum IGF-I stimulated and basal cartilage sulphation in vitro, in a dose-dependent manner. Serum IGF-I bioactivity of diabetic sera showed a change in activity over the 24-h period, with peak inhibitory bioactivity observed in each subject between 0800 and 1000 h. BP-28 concentrations in each individual showed a marked circadian rhythm with maximum peak levels occurring at 0800 h. Long-acting insulin administered in the evening in two of the diabetic subjects blunted the maximum peak level attained compared to the three diabetics who had long-acting insulin administered in the morning. IGF-I concentrations did not change over the 24-h period in each individual. The data shows that BP-28 inhibits serum IGF-bioactivity on cartilage in vitro. The changes in inhibitory bioactivity observed in diabetic serum are associated with similar changes in serum concentrations of BP-28. We propose that BP-28 is one of the IGF-I inhibitors observed in diabetic serum and that it may play a role in retarded growth and delayed puberty often seen in the adolescent diabetic.

Adolescent↗

The dawn phenomenon is related to overnight growth hormone release in adolescent diabetics.

We have investigated the relation between nocturnal insulin requirements and nocturnal growth hormone (GH) release in 26 diabetic adolescents at various puberty stages and have examined the effect of nocturnal GH suppression on pre-breakfast insulin requirement. In all the studies, euglycaemia was maintained overnight using a computer-calculated variable-rate insulin infusion, and 15-min blood samples were collected for GH assay. During initial clamp studies, insulin infusion rates were greater from 0500-0800 h (15.22 +/- 0.95 mU/kg/h, mean +/- SEM) than from 0100-0400 h (12.42 +/- 0.84 mU/kg/h, P less than 0.001). The increase in insulin infusion rate correlated with mean overnight GH concentration (r = 0.68, P less than 0.001), and was maximal at puberty stage 3 in both sexes. In seven of the subjects, a second identical clamp was performed following administration of 100 mg oral pirenzepine. During these studies, mean overnight GH levels were reduced by 11-85%, from 17.6 +/- 1.6 to 7.5 +/- 2.2 mU/l; P less than 0.01. Insulin requirements were not significantly different between the periods 0100-0400 and 0500-0800 h during these studies, and the reduction in pre-breakfast (0500-0800 h) insulin requirement when compared with the baseline studies correlated with the fall in GH secretion (rs = 0.82, P less than 0.01). The dawn increase in insulin requirement in adolescents with IDDM is related to the overnight GH secretion during puberty, and pre-breakfast insulin requirement can be reduced by suppressing nocturnal GH release.

Adolescent↗