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Biomedical subjects

L J Miller

Publications and source records attributed to L J Miller.

At least 235 records · Page 13Linked to original sources
PubMed1983

The role of gastrointestinal hormones in the control of postprandial and interdigestive gastrointestinal function.

Gastric, pancreatic, biliary, and intestinal functions during interdigestive and postprandial periods can now be quantified and correlated with changes in gastrointestinal hormone concentrations. Through this type of study, we can begin to glimpse the physiological roles of gastrointestinal hormones. The segments of the gastrointestinal tract which regulate each digestive function can be determined by experimental manipulations in which postprandial chyme is diverted from or exposed to particular areas of the bowel through the use of occlusive balloons. These studies suggest that the upper gut is capable of regulating biliary and pancreatic function, while the stomach and the entire small bowel affect stomach function. In addition, gastric secretion is regulated more proximally than gastric emptying. Knowledge of the hormones present in different segments of the bowel permits hypothesis of their physiological regulatory functions.

Bicarbonates↗
PubMed1982

Human interdigestive and postprandial gastrointestinal motor and gastrointestinal hormone patterns.

Fasting gastrointestinal motor and hormone patterns were studied in 11 healthy volunteers. Cyclic motor activity was present in all subjects during fasting, but the duration and site of onset of each cycle were variable, even in the same subject. Fasting gastrin, GIP, and glucagon levels remained low and constant during the 8-hr study, while plasma motilin levels exhibited cyclic variation in 7 of the 11 subjects. Achlorhydria (induced with cimetidine in 5 of the 11 subjects) did not alter the pattern of fasting motor activity or plasma motilin. In the remaining six subjects, the effect of liquid nutrient meals was examined. Ingestion of a sodium chloride bolus failed to disrupt fasting cyclic activity, while all nutrient-containing solutions inhibited gastric phase-2 motor activity, the duration of inhibition being longest for the mixed and lipid meals. All nutrient meals released GIP, while only protein and mixed meals released gastrin, and the lipid meal released motilin. Our study confirms the rhythmicity of interdigestive motor cycles in man and demonstrates their lack of dependence on gastric acid secretion and some relationship to motilin cycles in certain individuals as determined by radioimmunoassay. Transition from fasting to fed pattern (after liquid meals) is characterized by the inhibition of phasic gastric pressure changes in the antrum and the development of irregular activity in the intestine, similar in pattern to fasting phase 2. Because the duration of interruption of the gastric interdigestive pattern by meals depends on their nutrient content, we conclude that dietary composition may be a major determinant of the fasting-fed motor balance in man.

Achlorhydria↗
PubMed1982

Pancreatic exocrine function in severe human chronic renal failure.

Patients with chronic renal failure have an abnormal immunoreactive gastrointestinal hormone profile, which is characterised by raised fasting serum concentrations of hormones that have antagonistic effects on exocrine pancreatic function. In addition, in this present study we have found that in renal insufficiency cholecystokinin disappears slowly from the plasma after a constant intravenous infusion of the hormone (p = 0.05 compared with healthy subjects). To evaluate whether the stimulatory or inhibitory hormones have a predominant effect, pancreatic exocrine function under conditions of mannitol perfusion of the duodenum and continuous intravenous cholecystokinin stimulation was studied in eight patients who had severe chronic renal failure and eight age-matched and sex-matched control subjects. Compared with healthy subjects, patients with renal insufficiency had hypersecretion of trypsin in response both to mannitol perfusion of the duodenum and to cholecystokinin stimulation (p less than 0.05). No significant differences in lipase secretion were noted between the patients with renal insufficiency and control subjects. These findings are consistent with the hypothesis that, of the abnormally raised fasting serum concentrations of gastrointestinal hormones found in renal insufficiency, hormones that stimulate rather than inhibit pancreatic exocrine function predominate. Secondly, the dissociation between trypsin and lipase outputs in chronic renal failure may suggest a differential trophic influence of stimulatory hormones -- that is, hypercholecystokininaemia -- on pancreatic exocrine enzyme secretion.

Adult↗
PubMed1982

Nutrient and bowel segment dependency of human intestinal control of gastric secretion.

The gastric secretory effects of protein, fat, and carbohydrate infused at different levels of the small bowel were investigated in seven healthy subjects. Similar caloric loads (53.4 kcal) of protein (essential amino acids), lipid (oleic acid), and carbohydrate (glucose) in isomolar (280 mosmol/l) similar pH (7.4) solutions were infused into 60-cm segments of small bowel (isolated between two occlusive balloons), located distal to the ligament of Treitz (proximal), proximal to the ileocecal valve (distal), and between the two (middle). A submaximal gastric secretory background was provided by continuous intravenous pentagastrin. Protein stimulated acid secretion in the proximal (increase of 8.7 meq/h, representing 84 +/- 5% of control level) and middle (increase of 1.9 meq/h, representing 16 +/- 2% of control level) segments, while it inhibited acid secretion when infused into the distal segment (decrease of 3.7 meq/h, representing 33 +/- 4% of control level). In contrast, both lipid and carbohydrate inhibited acid secretion similarly (33-38% of control level) at all levels of the bowel. The different effects of protein at different levels of the bowel could not be explained by differences in serum gastrin, different degrees of absorption, or different postabsorptive levels of alpha-amino nitrogen. This suggests the presence of hormonal (nongastrin) or neural mechanisms in the proximal bowel to stimulate acid secretion and/or in the distal bowel to inhibit acid secretion. Thus, factors that determine specific nutrient loads to specific segments of bowel can have important physiological effects on gastric acid secretion.

Adolescent↗
PubMed1982

Luteinizing hormone-releasing hormone involvement in the reproductive behavior of a male amphibian.

The present study demonstrates that an intracerebroventricular injection of luteinizing hormone-releasing hormone (LHRH) activates sexual behaviors and elevates the plasma androgen concentrations in rough-skinned newts (Taricha granulosa). The stimulatory effect of LHRH on male behavior may be a seasonal phenomenon, because LHRH stimulation of sexual behavior was only observed during the early part of the breeding season (November and December). When an active LHRH antagonist was injected into male newts, sexual behavior was suppressed. These studies indicate that endogenous LHRH is involved in regulating sexual behavior in this amphibian.

Animals↗
PubMed1982

Giant hypertrophic gastropathy (Ménétrier's disease): pharmacologic effects on protein leakage and mucosal ultrastructure.

Seven patients with giant hypertrophic gastropathy participated in a gastric intubation perfusion study to investigate the route and mechanism of protein leakage associated with this disease. All patients had gastric tight junctions wider than those in healthy controls. Acute administration of propantheline bromide reduced gastric albumin leakage (-50.7%, p less than 0.05) and concurrently decreased width of tight junctions (p less than 0.05) in all patients. Another antisecretory agent, cimetidine, had no consistent effect on protein leakage or on the width of tight junctions. Pentagastrin and bethanechol chloride increased protein loss but had no effect on the width of tight junctions. These results are consistent with the hypothesis that proteins may take a paracellular route via the tight junctions as they traverse the gastric mucosa and that this may have a cholinergic mechanism.

Adult↗
PubMed1981

Intestinal control of human postprandial gastric function: the role of components of jejunoileal chyme in regulating gastric secretion and gastric emptying.

Intestinal control of gastric secretion and emptying were studied in healthy humans by using intubation-marker-perfusion techniques. An occluding balloon was used to separate the jejunoileal test segment from the more proximal gut. Mixed-nutrient, semielemental meals (300 and 600 calories) were administered while varying the jejunal perfusate: normal saline, jejunal chyme or its protein (casein hydrolysate), lipid (oleic acid), or carbohydrate (maltose) components. The meal in contact with the stomach and duodenum increased gastric secretion above fasting levels. This was partially inhibited by whole chyme in contact with the jejunum, the lipid and carbohydrate components of chyme mediating this inhibition. Jejunoileal chyme inhibited gastric emptying, with all three nutrient components acting as inhibitors. Effects on gastric secretion and emptying were dose-dependent, being greater after the larger meal and most prominent in the early postprandial period; these effects on gastric emptying were more prominent than those on gastric secretion. These results suggest that the intestinal phase of gastric function is directed mainly toward regulation of the reservoir function of the stomach: to adapt the gastric delivery of nutrients and fluid to the capability for efficient digestion and absorption.

Adult↗
PubMed1980

Dysfunctions of the stomach with gastric ulceration.

Factors implicated in the pathogenesis of gastric ulcer were studied simultaneously in seven patients with strictly defined type 1 gastric ulcer (single benign ulcer above the incisura of the stomach) and in six healthy controls. After ingestion of an ordinary solid-liquid meal, patients with gastric ulcer demonstrated gastric hyposecretion of acid, pepsin, and water; delayed gastric emptying of solids with normal emptying of liquids; and increased intragastric concentrations of bile acids. These functional abnormalities appear to be interrelated. Metoclopramide, administered orally in a double-blind fashion, ameliorated the defect in the emptying of solids and the high concentrations of bile acid in the gastric contents. The ability of this drug to break this interdependent cycle suggests the need for further clinical investigation.

Achlorhydria↗
PubMed1980

Gastric, pancreatic, and biliary responses to meals in hyperthyroidism.

Upper gastrointestinal function in response to a mixed nutrient meal was evaluated in hyperthyroid patients, both before and after therapy, and in healthy controls. Gastric secretion, gastric emptying, and pancreatic secretion were all normal and normally integrated postprandially in the hyperthyroid patients. Bile acid output was reduced (P less than 0.05) in this group of patients relative to healthy controls. Duodenal bile acid concentrations, however, were above the critical micellar concentration in most of the hyperthyroid patients, and the bile acid output and concentration remained unchanged in all patients three months after treatment. After radioactive iodine therapy, when gastrointestinal symptoms were returning toward normal, a small but statistically significant increase in gastric secretion was observed. However, gastric emptying and pancreatic secretion, like biliary secretion, remained unchanged. Abnormalities responsible for the diarrhoea and steatorrhoea in hyperthyroidism appear to reside primarily distal to the duodenum. However, reduced bile acid output may be a contributory factor in some patients.

Adult↗
PubMed1980

Application of recategorized WISC-R scores for adjudicated adolescents.

Bannatyne's recategorization of WISC-R scores was applied to 97 juveniles who had been adjudicated by the juvenile court system to a diagnostic and evaluation unit in Eastern Alabama. Mean ranks werre analyzed using the Friedman test for repeated-measures analysis of variance. The total sample exhibited a significant mean rank pattern of scores in the following descending order: Spatial, Conceptual, Sequential, and Acquired Knowledge. Subgroup patterns varied for those youths with IQs 90 and above (Conceptual, Spatial, Sequential, and Acquired Knowledge) and IQs below 90 (Spatial, Sequential, Conceptual, and Acquired Knowledge). Pairwise comparisons using the Scheffé procedure indicated significant differences between the Spatial score and Acquired Knowledge score for the total group and those youths with IQs below 90. The study extended the application of recategorized scores for adjudicated youth suggested by Bannatyne (1968, 1971, 1974). This investigation affirms the need for further studies of the differential effect of IQ on the patterns of WISC-R scaled scores.

Adolescent↗
PubMed1980

Dyspepsia, antral motor dysfunction, and gastric stasis of solids.

Extensive gastric manometric and emptying studies were performed in a patient with postprandial dyspeptic symptoms which, for many years, had been diagnosed as functional complaints. After ingestion of a mixed, solid-liquid meal we observed marked gastric stasis of solids associated with a weak antral pressure response, whereas gastric emptying of fluids was normal. Fundic pressure activity, recorded separately, was also normal. This case may represent a pathophysiologic expression of the specific roles of the antrum in the emptying of solids (abnormal) and of the fundus in the emptying of liquids (normal) and shows that pathophysiologic abnormalities can sometimes be demonstrated in patients lumped under a "functional" category.

Aged↗