Correlation of cardiovascular and neuroendocrine tests of autonomic function in diabetes

Six normal subjects and 16 insulin-dependent diabetics with varying degrees of autonomic damage each had blood sampled for norepinephrine and pancreatic polypeptide for fifteen minutes after a mixed meal and intravenous (IV) edrophonium (Tensilon). The normal subjects showed a brisk but short-lived rise in norepinephrine after edrophonium (average maximum increase 70% between 2 and 6 minutes), as did most diabetics. However, diabetics with cardiovascular reflex evidence of sympathetic damage showed no rise in norepinephrine. Pancreatic polypeptide concentrations increased up to 400% above baseline after a mixed meal in both the normal and the diabetic group with normal cardiovascular reflexes. There was no significant rise in pancreatic polypeptide either in the diabetics with parasympathetic damage alone or in those with additional sympathetic damage. These results provide further evidence for the diffuse nature of the damage in diabetic autonomic neuropathy.

Endocrine and exocrine pancreatic function in treated coeliac disease

Pancreatic function was assessed prospectively in a group of 18 treated adult coeliac patients, most of whom were asymptomatic. The para-aminobenzoic acid (PABA) test indicated exocrine pancreatic insufficiency in three patients, all of whom had persisting gastrointestinal symptoms. Arginine, 5 g intravenously, was used to stimulate pancreatic islet cells; basal and stimulated concentrations of plasma insulin, C-terminal glucagon, N-terminal glucagon, and blood glucose did not differ from asymptomatic nondiabetic control subjects. After gluten withdrawal, coeliac patients who responded clinically had no evidence of significant pancreatic impairment, but consideration of exocrine pancreatic insufficiency is worthwhile in those patients with persisting symptoms.

Gastric emptying of a solid-liquid meal and gastro-intestinal hormone responses in patients with erosive oesophagitis

Abnormal gastric motility has been recognised recently in some patients with excessive gastro-oesophageal reflux. The cause of this motility disturbance is unknown. A dual isotope study has been used to assess gastric emptying of solid and liquid components of a test meal in 16 patients with erosive oesophagitis and in 16 control subjects. The release of insulin, gastrin, pancreatic polypeptide, gastric inhibitory polypeptide and neurotensin in response to the test meal was monitored in all subjects. A significant delay in both solid and liquid emptying was observed in patients with erosive oesophagitis. However, they demonstrated no alteration in the pattern of hormone release in response to the test meal.

Circulating gastrointestinal hormones in patients with flatulent dyspepsia, with and without gallbladder disease

Fasting and post-prandial circulating levels of insulin, gastrin, gastric inhibitory polypeptide, pancreatic polypeptide and neurotensin were measured in patients with flatulent dyspepsia, with and without gallbladder disease and post-cholecystectomy. Levels were also measured in non-dyspeptic patients with gallbladder disease and normal controls. There were no consistent significant differences from controls for fasting and post-prandial responses in patients with a history of dyspepsia or those who experienced dyspepsia at the time of the test. In patients with gallbladder disease, with and without dyspepsia, there was a reduced neurotensin response compared to normal controls. It is concluded that circulating levels of these hormones are not related to symptoms of flatulent dyspepsia.

Meal-stimulated neurotensin immunoreactivity in plasma following gastric surgery: characterisation with two region-specific antisera

Plasma neurotensin (NT) response to a simple fatty meal, administered via an indwelling naso-gastric tube, has been assessed in two groups of subjects following gastric surgery without resection, and in healthy controls. Two region-specific NT antisera were employed in the radioimmunoassay (RIA) of plasma samples. The first, NT3, recognises only NT 1-13 in plasma extracts, while the second, GNT 21, recognises NT 1-13, NT 1-11 and NT 1-8 equally. In addition, plasma extracts were subjected to reverse-phase high performance liquid chromatography, fractions from which were subjected to each region-specific RIA. There was no significant response to the test meal in the healthy controls. However, both groups of post-gastric surgery subjects, who had undergone either vagotomy and pyloroplasty (V & P) or vagotomy and gastrojejunostomy (V & GJ), displayed significant increases in both intact and N-terminal plasma NT immunoreactivity (IR). The integrated responses of the V & P and V & GJ groups were also significantly higher than the control response but did not differ significantly from one another. The proportion of intact NT to total N-terminal NT-IR in each group was not significantly different.

The effect of oral alcohol on gastroenteropancreatic hormones in volunteers

This study has examined changes in gastrointestinal hormones induced by alcohol. Ten normal volunteers consumed an orange and carbohydrate-containing drink on two separate occasions, with and without 50g alcohol. There was a significant hyperglycaemia associated with alcohol ingestion but no difference was noted in insulin or gastric inhibitory polypeptide in the two groups. Gastrin release was stimulated by alcohol but pancreatic polypeptide release and N-terminal glucagon release were both suppressed by alcohol. There was no difference in release of secretin or C-terminal glucagon in either group.

The effect of chronic treatment with a non-selective beta-adrenoceptor antagonist on the enteroinsular axis and intermediary metabolites

In a single-blind randomized placebo-controlled cross-over study in hypertensive patients we have examined the effects of treatment with the non-selective beta-adrenoceptor antagonist nadolol on the responses of glucose, intermediary metabolites and the hormones of the enteroinsular axis to the ingestion of a mixed meal. During treatment with nadolol the plasma insulin concentration 30 min after ingesting the meal was significantly lower than on placebo and the plasma glucose rose more slowly. Plasma concentrations of GIP tended to be higher during nadolol than placebo treatment. No significant effects of treatment with nadolol were noted on pancreatic glucagon or intermediary metabolites.

Characterization of immunoreactive forms of pancreatic polypeptide in islet cell tumors using antisera with different regional specificities

Tumor tissue from a heterogeneous group of patients with clinically and histologically diagnosed islet cell tumors has been assessed for pancreatic polypeptide (PP) content using radioimmunoassay. Immunoreactive forms of PP, obtained by gel filtration of tissue extracts, were detected using antisera with different regional specificities. Normal pancreatic tissue contained one form of PP coeluting with human PP whereas, tumor tissue from patients with insulinoma, Zollinger-Ellison, and WDHA (watery diarrhea hypokalemic achlorhydric) syndromes contained, in addition, higher molecular weight forms of immunoreactive PP. Furthermore, a lower molecular weight form was detected in tumor tissue from a Zollinger-Ellison syndrome patient. The high molecular weight forms of immunoreactive PP were not recognized using a C-terminal-specific antiserum, whereas the smaller form was only detected using this antiserum. The variation in cross-reactivity observed with two antisera in this study emphasizes the limitations of using a single antiserum to detect molecular forms of peptide hormones, particularly those in islet cell tumors.

Pulmonary hypertension, systemic lupus erythematosus, and the contraceptive pill

Pulmonary hypertension in systemic lupus erythematosus (SLE) in the absence of chronic parenchymal lung disease or pulmonary emboli is rare. We report such a case with an acute and rapidly progressive onset of symptoms in a patient who had started taking the contraceptive pill eight months previously.

Influence of a transplantable insulinoma on the pancreatic status of insulin and pancreatic polypeptide in the rat

The effect of endogenous hyperinsulinaemia, produced by syngeneic transplantation of rat insulinoma at an extrapancreatic site, on pancreatic insulin and pancreatic polypeptide has been examined by radioimmunoassay and immunohistochemistry. Twenty days after subcutaneous transplantation, tumour-bearing rats exhibited marked hyperinsulinaemia and hypoglycaemia, with plasma pancreatic polypeptide concentrations similar to controls. Immunoreactive insulin levels in the head and tail of pancreas of tumour-bearing rats were reduced by 90-95% compared with control animals. Immunoreactive pancreatic polypeptide levels in the head of the pancreas were reduced by 70%, but the relatively low levels of peptide in the pancreatic tail were similar in tumour-bearing and control rats. Insulin and pancreatic polypeptide cells were weakly immunofluorescent in tumour-bearing rat pancreas. In conclusion, the presence of an insulinoma at an extrapancreatic site resulted in a severe depletion of endogenous insulin and pancreatic polypeptide, suggesting that there is a functional relationship between the beta and pancreatic polypeptide cell.

Cimetidine fails to suppress the rise in plasma secretin during fasting

The effects of cimetidine on plasma secretin were studied during prolonged fasting in order to determine whether gastric acid output influences secretin release under these circumstances. Twenty healthy volunteers starved for 36 h and were refed with oral glucose. They were given placebo or cimetidine (1.6 g daily) for 24 h before and during the starvation period. After 12 h fasting plasma secretin like immunoreactivity (SLI) was lower (P less than 0.02) in the cimetidine group than in the placebo group. After 36 h plasma SLI was higher (P less than 0.001) in both groups compared to the 12 h value but there was no statistically significant difference between the 2 groups. Refeeding caused prompt suppression of plasma SLI in both groups. Plasma gastrin was lower (P less than 0.001) after 36 h than 12 h in the placebo group only, but there was no significant difference between the groups. Blood glycerol (P less than 0.01) and 3 hydroxybutyrate (P less than 0.02) concentrations were higher after 36 h than after 12 h fasting in both groups. During fasting, sufficient to cause mobilisation of fat and ketosis, cimetidine failed to suppress plasma SLI. This may be due to inadequate suppression of gastric acid output or to some alternative stimulus to secretin release during fasting.

Vincristine-induced abnormalities of gastrointestinal regulatory peptide cells of the rat. An immunocytochemical study

The microtubule-disrupting drug vincristine is a common component of anti-cancer chemotherapeutic regimes, which produces acute constipation as a side effect. Although generally attributed to damage to the myenteric plexus, the precise mechanism of this disturbance is unknown. In addition, vincristine causes marked aberrations in the secretory response of pancreatic endocrine tissue in both man and rats. No information is available on its possible effect on regulatory peptides of the gastrointestinal tract. In this study we have produced vincristine-induced constipation in rats at a dosage comparable with that employed in the treatment of human subjects. Immunocytochemistry revealed concomitant disturbances in cells exhibiting immunoreactivity for gastrin in the antrum, for gastric inhibitory polypeptide and 5-hydroxytryptamine in the duodenum, for enteroglucagon in the colon, and for somatostatin in all three sites. These widespread effects are transient in nature with normal cell numbers and morphology being reestablished within 6 days. It is suggested that the observed effects are a direct result of microtubule disruption and that gastrointestinal regulatory peptide and amine immunoreactive cells have a rapid regeneration potential.

Effect of acarbose on biochemical responses and clinical symptoms in dumping syndrome

A dose of 50 mg of acarbose was administered with a standard breakfast to 13 subjects with dumping syndrome. Significant attenuation of hyperglycaemia (p less than 0.01) was observed, and rises in plasma gastric inhibitory polypeptide, insulin and enteroglycagon were reduced (p less than 0.05). Plasma levels of neurotensin, vasoactive intestinal polypeptide and somatostatin were not affected. Dumping score was reduced, but this did not achieve statistical significance. In a longer-term study, 9 patients took acarbose, 50 mg t.i.d., for 1 month. No significant reduction in the number or severity of dumping attacks was observed, but a majority expressed a preference for the drug and some individuals experienced a marked improvement of symptoms.

Gastrointestinal hormones in anorexia nervosa

A study was undertaken of fasting and post-prandial blood levels of glucose and a number of gastrointestinal hormones in patients with anorexia nervosa. After an overnight fast their blood levels of glucose, insulin and pancreatic glucagon were significantly lower than those of age-sex matched healthy volunteers. There were no significant differences in the levels of gastrin, total glucagon-like immunoreactivity, vasoactive intestinal polypeptide, pancreatic polypeptide, secretin and gastric inhibitory polypeptide. Serial blood samples were taken for up to two hours after the ingestion of a standard mixed meal (450 kcal) and these showed a significant glucose intolerance, a reduced and delayed insulin response, and a reduced release of gastric inhibitory polypeptide, as compared with the controls. There was an increased release of pancreatic polypeptide but the difference in the post-prandial hormone profile between patients and controls for gastrin did not reach statistical significance.

Suppression of somatostatin release by duodenogastric reflux in dogs

The effect of duodenogastric reflux on systemic and portal venous blood concentrations of somatostatin has been studied in the dog. Duodenogastric reflux suppressed somatostatin concentrations in both systemic and portal venous blood, but this did not occur when bile alone was diverted into the stomach. The suppression was also much less marked when truncal vagotomy accompanied the reflux. These findings suggest that altered somatostatin activity may play a part in the production of the pathophysiological changes occurring in clinical conditions such as peptic ulceration, in which there is an increase in duodenogastric reflux.

The effect of starvation on the gastro-entero-pancreatic hormonal and metabolic responses to exercise. (GEP hormones in starvation and exercise)

Gastro-entero-pancreatic hormonal and metabolic responses to bicycle ergometer exercise for one hour following twelve hours fasting (P1) and 36 hours fasting (P2) were compared. During P1 plasma secretin and blood glycerol increased. Pre-exercise concentrations of plasma C-terminal glucagon-like-immunoreactivity (C-GLI), secretin, blood glycerol, 3-hydroxybutyrate and lactate were higher after 36 hours fasting than 12 hours fasting. During P2 glycerol rose sharply while secretin, C-GLI and 3-hydroxybutyrate remained higher than during P1. A role for secretin and C-GLI in accelerated lipolysis during fasting and exercise is possible.

Physiological circulating levels of secretin-like immunoreactivity in the human do not stimulate free fatty acid production

An in vivo study was carried out to establish whether infused secretin, which achieves physiological levels of secretin-like immunoreactivity (SLI), promotes lipolysis. Six healthy volunteers received two infusions after separate 8 h overnight fasts. The paired infusions of either 500 ml of normal saline or 150 C.U. of porcine secretin in 500 ml of normal saline were infused at a constant rate of 1.38 ml/min. Venous blood was sampled at 0, 1, 2, 3, 4, 5 and 6 h after the infusion started. Mean plasma concentrations of SLI were significantly higher after infusion of saline with secretin in comparison to infusion of saline alone but remained within the physiological range. Mean serum free fatty acid (FFA) and 3-hydroxybutyrate concentrations rose significantly with time during both infusions but the mean FFA and 3-hydroxybutyrate concentrations did not differ significantly between infusions at each time of assessment. We conclude that a lipolytic role for secretin has not been shown to be of importance in relation to the in vivo rise in FFA concentrations observed in the fasting normal subject.

Predicting the need for insulin therapy in late onset (40-69 years) diabetes mellitus

A six-year prospective study of 144 newly diagnosed, symptomatic diabetic patients aged 40-69 years showed that 21 (15%) required insulin therapy, commencing 1-61 months after diagnosis. The plasma insulin response to oral glucose was assessed at the time of diagnosis. All 12 patients with very low peak insulin response (less than or equal to 6 mU/l) required insulin therapy. Thirty-six patients had an intermediate insulin response (greater than 6 less than or equal to 18 mU/l); of these, 7 with a mean weight 88% (range 73-96%) of average body weight required insulin, while 29 with a mean weight 117% (range 98-158%) of average body weight, did not. Ninety-six patients had a peak insulin response (greater than 18 mU/l); 2 patients whose weights were 96% and 100% of average body weight, required insulin, while the remainder did not. Consideration of initial body weight and peak insulin response provides a useful prediction of the eventual need for insulin.

Glucagonoma syndrome demonstrating giant duodenal villi

A 39 year old man developed an itchy bullous rash in the perineum and on the extremities. Six years later, after giant intestinal villi had been noted at endoscopy, a diagnosis of the glucagonoma syndrome was made. Investigation revealed a large tumour of the pancreatic body and tail. The molecular species of glucagon secreted by the tumour were characterised using the combined purification procedures of immunoaffinity chromatography followed by gel filtration.

Radioimmunoassay for pancreatic polypeptide, and its age-related changes in concentration

Pancreatic polypeptide (PP), a recently discovered pancreatic hormone, is potentially a marker for endocrine tumors. Consequently, we devised a radioimmunoassay for it, using antisera (raised in rabbits) to bovine PP, 125I-labeled bovine PP (purified by anion-exchange chromatography), and human PP standards. Concentrations circulating in fasting, normal subjects were measured. Statistical analysis of the results revealed a skewed distribution. An age-related increase was also observed. Evaluating PP concentrations in sera from 23 patients with endocrine tumors, we found increased values in a few cases of Zollinger-Ellison syndrome, medullary carcinoma of the thyroid, carcinoid syndrome, and one tumor producing vasoactive intestinal polypeptide (VIPoma). In contrast, values from five insulinomas and one glucagonoma were within the normal reference interval. Thus, an increased value for PP in a fasting individual may suggest the diagnosis of an endocrine tumor but is not a diagnostic prerequisite.

Radioimmunoassay for pancreatic polypeptide, and its age-related changes in concentration

Pancreatic polypeptide (PP), a recently discovered pancreatic hormone, is potentially a marker for endocrine tumors. Consequently, we devised a radioimmunoassay for it, using antisera (raised in rabbits) to bovine PP, 125I-labeled bovine PP (purified by anion-exchange chromatography), and human PP standards. Concentrations circulating in fasting, normal subjects were measured. Statistical analysis of the results revealed a skewed distribution. An age-related increase was also observed. Evaluating PP concentrations in sera from 23 patients with endocrine tumors, we found increased values in a few cases of Zollinger-Ellison syndrome, medullary carcinoma of the thyroid, carcinoid syndrome, and one tumor producing vasoactive intestinal polypeptide (VIPoma). In contrast, values from five insulinomas and one glucagonoma were within the normal reference interval. Thus, an increased value for PP in a fasting individual may suggest the diagnosis of an endocrine tumor but is not a diagnostic prerequisite.