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Biomedical subjects

S R Bloom

Publications and source records attributed to S R Bloom.

At least 973 records · Page 54Linked to original sources
PubMed1982

Pancreatic and gastrointestinal hormones in chronic pancreatitis.

Pancreatic and gut hormones have been measured in 39 patients with chronic pancreatitis, 16 of whom had severe pancreatic insufficiency. Patients with pancreatic insufficiency had significantly diminished fasting levels and postprandial rises of pancreatic polypeptide which were less than 20% of normal. Patients with chronic pancreatitis, with or without exocrine insufficiency, had two- to threefold higher plasma levels of motilin and enteroglucagon than controls. Plasma levels of insulin, pancreatic glucagon, gastric inhibitory polypeptide and gastrin were similar to normal in these patients. The pattern of response of these hormones to a test breakfast differs markedly from those seen in other gut disease states and may reflect pathophysiological mechanisms.

Adult↗
PubMed1982

Postnatal surges in plasma gut hormones in term and preterm infants.

Using sensitive radioimmunoassays we have measured and compared plasma concentrations of motilin, gastrin, enteroglucagon, neurotensin, gastric inhibitory polypeptide and pancreatic polypeptide in (a) 53 healthy, preterm infants at birth or preprandially at 2.5, 6, 13 or 24 days; (b) 45 normal, breast-fed, term infants at birth or preprandially at 6 or 16 days, and (c) 12 healthy fasting adults. Plasma concentrations of all six hormones rose during the neonatal period in both preterm and term infants, the first four of these hormones reaching levels which exceeded those seen in healthy fasting adults. The rate of increase and the magnitude of the changes were less in term infants than preterm infants. These changes in plasma hormone concentrations may be the result of enteral feeding. Gut hormones exert important effects on gut growth, secretion and motility and on intermediary metabolism, and the postnatal hormonal surges observed may play a key role in the postnatal adaptions to enteral feeding.

Aging↗
PubMed1982

Electron immunocytochemical localization of enkephalin-like material in catecholamine-containing cells of the carotid body, the adrenal medulla, and in pheochromocytomas of man and other mammals.

Enkephalin-like immunoreactivity has been localized to electron-dense secretory granules of cat and piglet carotid bodies and adrenal medullae, horse adrenal medulla, and also to human adrenal medulla and pheochromocytomas using a gold-labeled antibody technique performed at the electron microscopic level. The same granules were also demonstrated to exhibit dopamine-beta-hydroxylase-like immunoreactivity, which suggests a granular colocalization of amines and peptides in catecholamine-storing cells.

Adrenal Gland Neoplasms↗
PubMed1982

Acute rise of pancreatic polypeptide after electroconvulsive therapy.

Plasma pancreatic polypeptide concentrations rise by 320 +/- 81 per cent following administration of electroconvulsive therapy. This rise is observed in the first ten minutes despite premedication of patients with 0.6 mg atropine. Pancreatic polypeptide release is dependent on cholinergic tone and is very sensitive to atropine. The dramatic rise in pancreative polypeptide observed following electroconvulsive therapy probably results from vagal stimulation and reflects insufficient atropine premedication.

Atropine↗
PubMed1982

Elevated motilin levels in patients treated with antidepressant and neuroleptic drugs.

Constipation is a frequent effect of treatment with antidepressant and neuroleptic drugs as a result of interference with neuronal control of colonic muscular activity. Motilin, a circulating peptide, is involved in induction of myoelectric complexes in the colon. Significantly elevated circulating basal motilin levels were found in patients receiving tricyclic antidepressant drugs, mean 128 +/- 33 pmol/l (control 48 +/- 6 pmol/l) or neuroleptic therapy, mean 213 +/- 29 pmol/l (control 87 +/- 8 pmol/l).

Antidepressive Agents, Tricyclic↗
PubMed1982

Bombesin: action on gut hormones and calcium in man.

Bombesin, a peptide with widespread biological actions, has been demonstrated in human tissues by immunological methods. To investigate its effect in man, synthetic bombesin was infused at low doses in six male volunteers. Bombesin at 2.4 pmol kg-1 min-1 produced significant rises in plasma insulin, glucagon, pancreatic polypeptide, gastrin, cholecystokinin, motilin, glucose-dependent insulinotropic polypeptide, neurotensin, enteroglucagon, vasoactive intestinal polypeptide, and serum calcium. In contrast, bombesin caused a profound fall in parathyroid hormone levels and reduced plasma glucose concentrations. A late rise in plasma calcitonin was also observed. Bombesin had no significant effect on the pituitary hormones, TSH, GH, PRL, or cortisol. No hormonal changes or alterations in calcium were noted during saline infusions. Bombesin has a marked stimulatory effect on gastrointestinal hormones, which is unique and opposite to the effect of somatostatin, a potent inhibitor of gut hormone release. Bombesin also influences calcium-regulating hormones, either directly or through its action on gut hormones. The bombesin concentrations achieved with the dosages used were low enough to indicate a possible physiological role for the endogenous peptide.

Adult↗
PubMed1982

Regulatory peptides and neuron-specific enolase in the respiratory tract of man and other mammals.

This short review deals with the distribution and cellular localization, in the respiratory tract, of five regulatory peptides (substance P, bombesin, vasoactive intestinal polypeptide (VIP), cholecystokinin, and somatostatin) and of a newly discovered neuroendocrine enzyme marker, neuron-specific enolase. Bombesin is found in typical mucosal endocrine cells, whereas the other regulatory peptides--principally substance P and VIP--are found, in significant concentrations, in autonomic nerves of the wall of the airways. Substance P, a putative sensory neurotransmitter, is found in autonomic nerves closely associated with the mucosal epithelium and the bronchial smooth muscle. VIP nerves, on the other hand, appear predominantly to innervate blood vessels, seromucous glands of the upper respiratory tract, and bronchial smooth muscle. The presence of neuron-specific enolase in both mucosal APUD cells and autonomic nerves has established this newly discovered neuronal enzyme as a useful marker for the entire neuroendocrine system of the lung and its derivative neoplasms.

APUD Cells↗
PubMed1982

Peptidergic nerves.

In recent years the autonomic nervous system has been shown to consist of nerves containing a number of different neurotransmitter substances; a system far more complex than was originally thought. It has been demonstrated that a large part of the autonomic nervous system contains peptides, and that, in the gut, these nerves form a major complex that infiltrates the entire length and breadth of the tract. The detailed study of this peptidergic system has been facilitated by the development of specialised immunocytochemical methods, which have yielded information on the distribution and morphology of the various types of nerve. Thus, the distribution of these nerves can often be seen to parallel what is known about the actions of individual peptides. The majority of peptidergic nerves are intrinsic to the gut, forming, with the other intrinsic nerves, what appears to be a largely autonomous unit. This enteric system can be visualised as a "minibrain", under the general influence of the central nervous system but able to function, to a certain extent, by itself. The consequences of a breakdown in the normal functioning of this system can be seen in a number of gut diseases.

Animals↗
PubMed1982

Interdigestive motor activity in patients with systemic sclerosis.

Fasting antral, duodenal, and jejunal motor activity and plasma motilin and pancreatic polypeptide were studied in 14 patients with systemic sclerosis, 6 and 9 without clinical evidence of small bowel involvement, and 8 healthy control subjects. Normal interdigestive motor activity was present in control subjects and patients without intestinal involvement. However, cyclic motor activity was absent in 3 of the patients with intestinal disease and the motility index per interdigestive cycle (or per 6-h recording period in those without cyclic activity) was significantly less in the antrum (181 +/- 103 mm2 compared with 760 +/- 86 and 1116 +/- 96 mm2 for patients without involvement and healthy control subjects, respectively), duodenum (153 +/- 101 mm2 compared with 1425 +2- 186 nd 1055 +/- 241 mm2), and jejunum (268 +/- 131 mm2 compared with 1166 +/- 97 and 1105 +/- 128 mm2). Metoclopramide and bethanechol significantly increased motor activity at the three sites in all subjects but the magnitude of the metoclopramide response was less in patients with intestinal involvement. Fasting concentrations of motilin and pancreatic polypeptide exhibited cyclic variation with peak values occurring during phase 3 of the interdigestive cycle. Plasma motilin during each phase of motor activity was significantly higher in patients with scleroderma, with or without intestinal involvement, than in control subjects. The abnormal motor activity demonstrated here indicates a possible mechanism by which intestinal stasis and bacterial overgrowth could occur and by which clinical disturbances of intestinal transit might arise.

Adult↗
PubMed1982

Recent physiological studies of the alimentary autonomic innervation.

The optimum pattern of stimulation of the VIP-ergic fibres in the submaxillary gland of the cat has been investigated by comparing the effects of continuous stimulation at 2 Hz for 10 min with those of stimulation at 20 Hz for 1 sec intervals for the same period. Both the fall in submaxillary vascular resistance (SVR) and release of VIP from the gland are significantly increased when the same total number of impulses is delivered in bursts at the higher frequency. Comparison of submaxillary responses to stimulation in 1 sec bursts, over a wide range of frequencies, has shown that, in atropinised cats, the fall in SVR is linearly related to stimulus frequency over the range 2-60 Hz, and maximal at 80 Hz. In addition, the fall in SVR is linearly related to stimulus frequency over the range 2-60 Hz, and maximal at 80 Hz. In addition, the fall in SVR is linearly related to log VIP output from the gland over the whole of the frequency range 2-160 Hz. Stimulation in 1 sec bursts at 10 sec intervals has also shown that certain non-peptidergic autonomic responses are optimal at much higher stimulus frequencies than has hitherto been supposed on the basis of classical studies employing continuous stimulation. It is concluded that it is no longer justified to assume that autonomic nerve fibres are invariably characterised by low natural discharge frequencies or that they necessarily fire at relatively constant rates. The results obtained using bursts of stimuli also show how differential responses can be obtained in the same tissue simply by varying the stimulus frequency and pattern.

Animals↗
PubMed1982

The hormonal pattern of intestinal adaptation. A major role for enteroglucagon.

A number of human diseases with intestinal adaptation have been investigated, including acute infective diarrhoea, intestinal resection, jejuno-ileal bypass, coeliac disease, tropical sprue, chronic pancreatitis and cystic fibrosis. In all, the newly isolated hormone enteroglucagon appeared to be elevated in proportion to the degree of adaptation. In rats after gut resection and cold adaptation, enteroglucagon was also elevated and the degree of elevation correlated closely with the crypt cell production rate (CCPR). Chronic administration of somatostatin suppressed both enteroglucagon and CCPR, while bombesin stimulated both. A crude preparation of enteroglucagon was found to directly stimulate DNA synthesis in enterocyte cultures. It is thus concluded that, at present, the most likely candidate for the humoral component of intestinal adaptation is the hormonal peptide enteroglucagon.

Adaptation, Physiological↗
PubMed1982

Development of intestinal regulatory peptides in the human fetus.

The time of first appearance and subsequent development of eight regulatory peptides in the small and large intestine of human fetuses has been investigated. Gastrin, secretin, motilin, gastric inhibitory peptide, vasoactive intestinal peptide, enteroglucagon, and somatostatin were first detected as early as 8 wk of age, while neurotensin was only demonstrated at 12 wk. Adult patterns of distribution were established by 20 wk of age. Of the peptides examined only vasoactive intestinal peptide was localized to nerve fibers and these were seen clearly in the myenteric plexus at the 12-wk fetal stage and in the later fetuses in both the enteric plexuses. The concentrations of regulatory peptides increased steadily until term when they were close to adult levels. Secretin and vasoactive intestinal peptide showed only a single molecular size species by gel permeation chromatography but the other peptides showed multiple peaks, the ratios tending to change through the gestational period in favor of the smaller molecular sized moieties. Thus the regulatory peptide system of the gut is present in th early fetus and its role in the process of maturation requires investigation.

Chromatography, Gel↗
PubMed1982

The effects of naloxone and morphine on postprandial gastrointestinal hormone secretion.

Postprandial gastrointestinal hormone secretion was not affected by the intravenous administration of naloxone. However, after the administration of morphine, multiple effects were observed. Postprandial pancreatic polypeptide, motilin, and enteroglucagon secretion were abolished and there was a reduction in the secretion of insulin, gastric inhibitory polypeptide, and neurotensin. There was prolonged secretion of gastrin. Levels of vasoactive intestinal polypeptide, somatostatin, and pancreatic glucagon were not affected. Many of these changes can be accounted for by the ability of morphine to delay gastric emptying. The prolonged secretion of gastrin could result from a combination of impaired gastric emptying and reduced postprandial gastric acid secretion. Inhibition of vagal acetylcholine release is the most likely explanation for the abolition of pancreatic polypeptide secretion. With the exception of the effects on motilin, pancreatic polypeptide, and enteroglucagon secretion this study provides no evidence that opiate substances directly affect the secretion of gastrointestinal hormones.

Adult↗