Persistent vomiting in patients with diabetes.
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Addison Disease↗
Biomedical subjects
S G Gilbey
Publications and source records attributed to S G Gilbey.
Individuals from multiplex insulin-dependent diabetes mellitus (IDDM) families express higher levels of TCRBV2S1 than controls.
T lymphocytes recognise peptide antigens through the T cell antigen receptor, which is composed of variable alpha and beta chains. There are forty-six functional variable regions on the beta chain. In this study the expression of the T cell receptor beta-chain variable regions 2S1 and 3S1, in a large cohort of multiplex insulin-dependent diabetes mellitus families, have been determined by use of monoclonal antibodies and flow cytometry. Peripheral blood was collected from these multiplex families and three control groups, healthy individuals, sporadic insulin-dependent diabetes mellitus patients and non-insulin-dependent diabetes mellitus patients. The level of TCRBV2S1 expression in the multiplex families was significantly higher than all the control groups for both the CD4+ and CD8+ T lymphocyte subsets. Detailed analysis of the family data showed that this increased expression was not associated with age, sex, HLA type or the diabetic phenotype. The TCRBV3S1 expression in all the diabetic cohorts was significantly lower than the healthy controls, in the CD4 subset only. Detailed analysis of the family data showed only the fathers TCRBV3S1 expression was lower than the healthy controls. This study gives further insight into TCRBV usage which could reflect the mechanism of the autoimmune response in IDDM multiplex families.
Adolescent↗
Male pseudohermaphroditism resulting from a novel mutation in the human steroid 5 alpha-reductase type 2 gene (SRD5A2).
The enzyme steroid 5 alpha-reductase, via NADPH, catalyses the conversion of testosterone to dihydrotestosterone, which is required for the embryonic differentiation of the external male genitalia and the prostate. An impairment of this reaction causes a form of male pseudohermaphroditism in which genetic males differentiate predominantly as phenotypic females. Molecular analysis of the 5 alpha-reductase type 2 gene in a patient with confirmed biochemical 5 alpha-reductase deficiency has resulted in the identification of a novel mutation, GAA to AAA, at codon 200. This mutation produces an amino acid change from glutamic acid to lysine, and may affect the ability of the enzyme to bind its co-factor.
3-Oxo-5-alpha-Steroid 4-Dehydrogenase↗
Lack of acute effect of amylin (islet associated polypeptide) on insulin sensitivity during hyperinsulinaemic euglycaemic clamp in humans.
It is suggested that amylin (islet associated polypeptide), co-secreted with insulin from the pancreatic beta cells acts as a circulating hormone which opposes the action of insulin on muscle and increases hepatic glucose production. We have tested the effect of amylin in human subjects on postabsorptive glucose homeostasis and on insulin sensitivity using the euglycaemic hyperinsulinaemic clamp. The amylin used opposed insulin-mediated glucose disposal in rat soleus muscle at concentrations of 10 nmol/l. Seven subjects were studied on two occasions and infused with either amylin or placebo for 6 h, initially when postabsorptive and then during a euglycaemic hyperinsulinaemic clamp. Mean plasma amylin concentrations during the first 3 h were 2006 +/- 327 pmol/l during amylin infusion and 20 +/- 9 pmol/l during the control infusion. Amylin infusion had no effect on postabsorptive plasma concentrations of insulin (control: 32 +/- 16 vs amylin: 25 +/- 8 pmol/l) or glucose (5.1 +/- 0.1 vs 5.3 +/- 0.1 mmol/l). During the clamp, amylin concentrations were 1636 +/- 422 pmol/l when it was infused and 24 +/- 6 during control infusions. Plasma glucose and insulin concentrations were well matched during the control and amylin infusions (glucose: 4.7 +/- 0.1 vs 4.8 +/- 0.1 mmol/l; insulin: 198 +/- 37 vs 195 +/- 22 pmol/l). Exogenous glucose infusion rates were a mean of 13% lower than control values during the amylin infusion but were not statistically different (p = 0.17).(ABSTRACT TRUNCATED AT 250 WORDS)
Adult↗
Naloxone-induced anorexia increases neuropeptide Y concentrations in the dorsomedial hypothalamus: evidence for neuropeptide Y-opioid interactions in the control of food intake.
We measured neuropeptide Y (NPY) concentration in microdissected hypothalamic nuclei, by radioimmunoassay, and NPY mRNA in the hypothalamus in rats treated systemically with the nonspecific opioid antagonist, naloxone, to produce mild anorexia. Twenty rats were treated with daily SC injections of naloxone (7.5 mg/kg); 20 were treated with vehicle alone. Naloxone produced a 7% reduction in food intake (p < 0.01) and a reduction in weight gain (p < 0.002). Neuropeptide Y concentrations were increased specifically in the dorsomedial nucleus of the hypothalamus (DMN) in rats treated with naloxone (6.8 +/- 0.7 fmol/micrograms protein vs. 3.1 +/- 1.0 fmol/micrograms protein, p < 0.05, n = 10 per group). Total hypothalamic NPY mRNA was unchanged. Neuropeptide Y-opioid interactions may be important in the control of food intake.
Animals↗
Localization of metastatic gastroenteropancreatic tumours by somatostatin receptor scintigraphy with [111In-DTPA-D-Phe1]-octreotide.
Most gastroenteropancreatic tumours express somatostatin receptors, allowing imaging using radiolabelled somatostatin analogues. Octreotide can be modified by coupling a DTPA moiety to the N-terminal D-phenylalanine to allow labelling with In111. We studied the comparative effectiveness of this radiopharmaceutical in identifying tumour extent. Twenty-two patients with metastatic gastroenteropancreatic tumours were scanned using [111In-DTPA-D-Phe1]-octreotide. In 11 patients with the carcinoid syndrome, one of six primary lesions was identified by CT scanning and by [111In-DTPA-D-Phe1]-octreotide scanning. Hepatic metastases were present in all patients, 9 of whom had positive scintigraphy. Two other sites of intra-abdominal uptake and four distant sites, not previously identified, were demonstrated. Five other distant sites were confirmed to be carcinoid metastases. All 11 patients with other gastroenteropancreatic tumours had positive scans, demonstrating 7/9 primary lesions, 12 intra-abdominal lesions, including hepatic metastases in all cases, and one distant lesion, all previously identified. Thus [111In-DTPA-D-Phe1]-octreotide imaging effectively identified the extent of metastatic disease from gastroenteropancreatic tumours, and confirmed lesions whose significance was uncertain following previous imaging procedures.
Adult↗
The effect of central blockade of kappa-opioid receptors on neuropeptide Y-induced feeding in the rat.
Neuropeptide Y (NPY) and the endogenous kappa-opioid receptor ligand, dynorphin (dyn), stimulate feeding when injected centrally in the rat. Norbinaltorphimine (norBNI, 25 nmol) reduced the feeding response to NPY (2.4 nmol) by 67% (P < 0.02). An additive effect of dynorphin and NPY was seen on food intake (saline 0.8 +/- 0.1, dyn 1.9 +/- 0.4, NPY 6.1 +/- 1.4, dyn and NPY 9.7 +/- 2.2). A component of NPY-induced feeding may be mediated by kappa-opioid neuronal systems.
Animals↗
Amino acid infusion blocks renal tubular uptake of an indium-labelled somatostatin analogue.
The Indium-labelled somatostatin analogue pentetreotide has been successfully developed for imaging of somatostatin receptor positive tumours. However there is significant renal tubular uptake of the radiolabelled peptide, which can obscure upper abdominal tumours and would preclude its use for targeted radiotherapy. The aim of this study was to determine whether amino acid infusion, which has been shown to block renal tubular peptide reabsorption, diminishes renal parenchymal uptake of this radiolabelled analogue. Eight patients being scanned with the 111In-labelled somatostatin analogue, pentetreotide, for localisation of gastroenteropancreatic tumours received an infusion of synthetic amino acids. The ratio of isotope uptake in kidney to that in spleen was assessed, and compared to the ratio for matched control patients, to determine if amino acid infusion reduced renal parenchymal uptake of the radiopharmaceutical. The amount of isotope in the urine was determined to ensure that any effect of the amino acid infusion was unrelated to changes in clearance. Infusion of amino acids significantly reduced renal parenchymal uptake of isotope at 4 h. There was a non-significant increase in urinary clearance of isotope over the 4 h, consistent with reduced reuptake and a lack of effect on glomerular filtration rate. This technique, by preventing renal damage, may allow the use of this somatostatin analogue for local radiotherapy, and could be of wider value in blocking tubular re-uptake of potentially nephrotoxic agents, such as radiolabelled Fab fragments.
Adult↗
Insulin and intestinal epithelial cell proliferation.
The effects of modification of the levels of endogenous plasma insulin on intestinal epithelial cell proliferation were investigated in rats maintained by total parenteral nutrition (TPN) using either a TPN diet that was high in glucose, or a low glucose (hypocaloric) TPN diet and in orally fed rats (normal and sham operated). The rats were put on their respective treatments for 7 days and were then injected with vincristine sulphate to arrest cells as they entered metaphase. Intestinal tissue was fixed for the determination of crypt cell production rate (CCPR) and blood plasma was taken for hormone radioimmunoassay. Sham operation had no effect on either plasma hormone levels or on CCPR. The standard TPN diet was associated with significantly reduced levels of gastrin, peptide YY and enteroglucagon. Gastrin and PYY were further reduced by the hypocaloric diet. However, plasma insulin was much increased in the TPN but not in the hypocaloric group. Small intestinal CCPR was reduced in the TPN groups, but no difference was observed between the standard and the low calorie TPN diets. The lack of difference in CCPR between the two TPN diets despite the massive elevation of plasma insulin strongly suggests that insulin does not have a substantial role in the control of gastrointestinal epithelial cell renewal.
Administration, Oral↗
Increases in neuropeptide Y content and gene expression in the hypothalamus of rats treated with dexamethasone are prevented by insulin.
The neurotransmitter neuropeptide Y (NPY) is abundant in the hypothalamus where its actions include the potent stimulation of food intake. The peripheral metabolic and hormonal signals involved in its regulation are not clear. The aim of this study was to investigate possible actions of corticosteroids and insulin on hypothalamic NPY synthesis and content in vivo. We measured NPY content in individual hypothalamic nuclei, and hypothalamic NPY mRNA by Northern blotting in whole hypothalamus in rats treated with dexamethasone (0.4 mg/kg/day) and dexamethasone plus insulin (60 U/kg/day), compared to controls. The effect of stopping dexamethasone treatment was also studied. Dexamethasone treatment produced significant increases in NPY in the paraventricular (11.0 +/- 1.3 vs. 7.1 +/- 0.4 fmol/micrograms protein, p < 0.05) and arcuate (6.2 +/- 0.3 vs. 3.8 +/- 0.2 fmol/microgram protein, p < 0.001) nuclei of the hypothalamus, paralleled by a 38% increase in total hypothalamic NPY mRNA (p < 0.05). These changes were not seen in the group treated with dexamethasone plus insulin. In the group in whom dexamethasone was stopped, NPY mRNA was unchanged compared to controls, but peptide content remained increased in the arcuate but not the paraventricular nucleus (arcuate 7.7 +/- 0.7 vs. 5.5 +/- 0.7, PVN 4.9 +/- 1.0 vs. 4.7 +/- 0.9 fmol/microgram protein). Thus hypothalamic NPY and its mRNA were increased by corticosteroid administration, and this effect was prevented by systemic insulin treatment. This dual regulatory system for hypothalamic NPY may be important in the control of food intake by corticosteroids and insulin.
Animals↗
Increased neuropeptide-Y messenger ribonucleic acid (mRNA) and decreased neurotensin mRNA in the hypothalamus of the obese (ob/ob) mouse.
The obese hyperglycaemic ob/ob mouse exhibits hyperphagia and other abnormalities of hypothalamic function. We measured hypothalamic concentrations of four peptides implicated in the control of appetite and energy expenditure, neuropeptide-Y (NPY), neurotensin, galanin, and somatostatin, by RIA and their respective mRNAs using semiquantitative Northern blotting. Using lean (+/+) mice as controls, we found unchanged concentrations of NPY, galanin, and somatostatin and a 25% reduction in neurotensin (P < 0.01). Neurotensin mRNA was similarly decreased (by 30%; P < 0.02), while NPY mRNA was increased 3-fold (P < 0.01). Centrally administered neurotensin decreases food intake, whereas NPY potently stimulates food intake. An increase in NPY gene expression together with reductions in neurotensin concentration and mRNA in the hypothalamus may be implicated in the development of hyperphagia and other neuroendocrine abnormalities seen in the ob/ob mouse.
Animals↗
A role for neuropeptide-Y, dynorphin, and noradrenaline in the central control of food intake after food deprivation.
A marked increase in food intake is observed in the rat after central injection of neuropeptide-Y (NPY), dynorphin, or noradrenaline (NA). Levels of both NPY and dynorphin are increased in the hypothalamus of food-deprived rats. The aim of this study was to explore the role of NPY, dynorphin, and NA in the central control of feeding after a period of food deprivation. We have investigated the effect of intracerebroventricular injection of a monoclonal antibody to NPY (NPYAb), a potent and selective kappa-opioid receptor antagonist norbinaltorphimine (norBNI), and the alpha-adrenergic antagonist phentolamine on fast-induced food intake. In animals provided with food after a 24-h fast, NPYAb given 10 min before presentation of food reduced food intake by 30% (P < 0.01) compared to that of animals pretreated with an antibody to chloroquine. A similar (34%; P < 0.05) reduction in fast-induced feeding occurred after pretreatment with norBNI. If norBNI was given together with NPYAb, then a reduction of 51% (P < 0.05) was observed. Pretreatment with phentolamine reduced fast-induced food intake by 39% (P < 0.05), with no evidence of an additive effect when phentolamine was given together with NPYAb. These data would support a role for endogenous NPY, dynorphin, and NA in the mediation of fast-induced feeding. NPY would seem to act independently of dynorphin, but through the same mechanism as NA.
Animals↗
Pleural involvement in the carcinoid syndrome.
Tissue fibrosis is a recognized complication of the carcinoid syndrome but pleural changes have not been described. Prompted by the finding of severe pleural thickening in two patients with the metastatic carcinoid syndrome but no thoracic metastases or previous pleural disease we reviewed the chest radiographs and CT scans in 50 patients with the carcinoid syndrome investigated from 1981 to 1990. Pleural abnormality was noted in 14 of the 50 patients (28%), five of whom had other possible causes for pleural disease. However, nine (18%) patients had 'idiopathic' pleural thickening. Pleural disease had developed within 2 years of the diagnosis in all cases, and seven of the nine patients had fibrosis elsewhere (heart valves, skin or mesentery). There were no features to suggest a more rapid disease progression in the patients with pleural disease. We suggest that the pleural abnormality is a complication of metastatic carcinoid disease.
Humans↗
The physiology of calcitonin gene-related peptide in the islet compared with that of islet amyloid polypeptide (amylin).
Following the discovery of a second gene containing a CGRP-like sequence, we demonstrated that "beta-CGRP" was indeed translated as a 37-amino acid peptide in vivo and was the predominant form of CGRP produced by the enteric nervous system. The presence of CGRP in the islet has been reported by several groups. We now show that beta-CGRP is again the major form. Another 37-amino acid peptide was recently isolated from islet amyloid deposits and found to have approximately 50% amino acid sequence homology with CGRP. Islet amyloid polypeptide, or amylin, is co-localized with insulin to the beta-cell secretory granule and is synthesized and released in parallel with insulin in response to a range of physiological and pharmacological stimuli. IAPP was subsequently shown, like CGRP, to inhibit the release of insulin pharmacologically. Interestingly, it was also shown to decrease the uptake of glucose by striated muscle, though it was considerably less potent than CGRP. This led to the suggestion that IAPP might be a circulating hormone regulating peripheral insulin sensitivity. Infusion of IAPP in human volunteers to produce plasma concentrations more than 100-fold higher than those seen physiologically, however, failed to alter peripheral glucose disposal. We conclude that beta-CGRP and IAPP are likely to play a role in local paracrine control of the islet.
Amyloid↗
Very high concentrations of islet amyloid polypeptide are necessary to alter the insulin response to intravenous glucose in man.
Islet amyloid polypeptide (IAPP) is a beta-cell peptide that can oppose insulin action in animal systems, but has not been shown to have any action in man; previously, we failed to show an effect of infused IAPP on iv glucose tolerance in human volunteers. We have reexamined its effects at even higher concentrations in six volunteers who received iv glucose (0.5 g/kg) during infusions of IAPP (25 and 50 pmol/kg.min) or normal saline. IAPP rose from a mean basal of 14.7 +/- 5.3 pmol/L to peak levels of 1,420 +/- 110, 2,240 +/- 140, and 27.7 +/- 9 pmol/L, respectively. IAPP at 25 pmol/kg.min had no effect on the plasma glucose disposal rate or the total incremental insulin response, but, in contrast, at 50 pmol/kg.min decreased the insulin response to glucose compared to the saline infusion (incremental area under the curve, 11,276 +/- 2,353 vs. 17,549 +/- 2,687 U; mean +/- SEM; P less than 0.02). This decrease was observed both during the first phase (0-10 min postglucose) insulin response (3,210 +/- 985 vs. 4,382 +/- 815 U; P less than 0.05) and the second phase response (11-90 min, 8,520 +/- 1,719 vs. 13,679 +/- 2,326 U; P less than 0.03). Glucose disposal rate, however, was unaffected (2.0 +/- 0.2 vs. 1.9 +/- 0.2). Thus, circulating IAPP concentrations greater than 90 times normal postprandial peaks were necessary to affect the insulin response to glucose. IAPP appears unlikely to be a circulating hormone influencing carbohydrate metabolism in man.
Adult↗
Increased neuropeptide Y content in individual hypothalamic nuclei, but not neuropeptide Y mRNA, in diet-induced obesity in rats.
Neuropeptide Y (NPY) is the most powerful appetite stimulant known, and chronic administration leads to obesity. The hypothalamic content of NPY varies with nutritional status, suggesting that it is of physiological importance. We measured NPY in specific hypothalamic nuclei and NPY mRNA in the hypothalamus by Northern blotting in rats made obese by feeding a highly palatable diet compared with controls fed standard chow. In animals fed the palatable diet, NPY concentrations were increased in the paraventricular nucleus (mean +/- S.E.M.; 19.5 +/- 2.3 vs 11.1 +/- 1.1 fmol/micrograms protein, P less than 0.02), the arcuate nucleus (20.4 +/- 3.3 vs 9.3 +/- 0.6 fmol/micrograms protein, P less than 0.01), the medial preoptic area (9.1 +/- 0.9 vs 5.9 +/- 0.7 fmol/micrograms protein, P less than 0.02) and the anterior hypothalamus (2.7 +/- 0.2 vs 2.0 +/- 0.1 fmol/micrograms, P less than 0.02). Hypothalamic NPY mRNA measured by Northern blot analysis was, however, unchanged. These results suggest that the increase in NPY was due to decreased release rather than increased NPYergic activity. The findings are in accord with the neuroendocrine disturbance and increased thermogenesis observed in this model of obesity.
Animals↗
Islet amyloid polypeptide: production by an osteoblast cell line and possible role as a paracrine regulator of osteoclast function in man.
1. The recently discovered peptide islet amyloid polypeptide shows considerable sequence homology with calcitonin-gene-related peptide, itself an alternative product of the calcitonin gene. The possibility that islet amyloid polypeptide might affect calcium homoeostasis and bone cell function was investigated. 2. Islet amyloid polypeptide messenger RNA was found to be expressed by human HTb 96 osteoblast-like cells in culture, and islet amyloid polypeptide immunoreactivity was present in the cell culture medium. 3. Infusion of islet amyloid polypeptide (150 pmol min-1 kg-1) caused a fall in serum calcium and phosphate concentrations in five patients with Paget's disease of the bone. This was similar to that caused by infusion of calcitonin (50 pmol min-1 kg-1). 4. These findings raise the possibility that islet amyloid polypeptide may act as a local factor within bone, produced by osteoblasts and regulating osteoclast function. The possibility of an action of islet amyloid polypeptide on the renal handling of calcium seems unlikely but is not totally excluded.
Aged↗