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J M Rhoads

Publications and source records attributed to J M Rhoads.

15 recordsLinked to original sources
PubMed1992

L-glutamine with D-glucose stimulates oxidative metabolism and NaCl absorption in piglet jejunum.

To explore the relationship between intestinal fluid absorption and oxidative metabolism, we measured the effects of amino acids and glucose on piglet jejunal ion transport and oxygen consumption (QO2) in vitro. Jejunal QO2 was stimulated by L-glutamine and D-glucose but not by the nonmetabolizable organic solutes methyl beta-D-glucoside or L-phenylalanine. QO2 was maximally enhanced by the combination of D-glucose and L-glutamine (5 mM). Even though 5 mM L-glutamine was previously found to be insufficient to stimulate NaCl absorption, 5 mM L-glutamine enhanced jejunal NaCl flux when combined with equimolar mucosal D-glucose. Either D-glucose or methyl beta-D-glucoside caused an increase in short-circuit current (Isc), an increase in Na+ absorption in excess of Isc, and a decrease in Cl- secretion, when L-glutamine was substituted for D-glucose (10 mM) on the serosal side. This relationship suggests that mucosal sugars, if combined with L-glutamine, enhance neutral NaCl absorption as well as electrogenic Na+ flow. (Aminooxy)acetate, an inhibitor of alanine aminotransferase, abolished the stimulation of QO2 and the NaCl-absorptive response to L-glutamine. We conclude that the oxidative metabolism fueled by L-glutamine is linked to a NaCl-absorptive mechanism in the intestine. We propose that the CO2 produced by glutamine metabolism yields carbonic acid, which dissociates to H+ and HCO3-, which may stimulate parallel antiports in the apical membrane.

Absorption↗
PubMed1991

L-glutamine stimulates jejunal sodium and chloride absorption in pig rotavirus enteritis.

Rotavirus enteritis is the leading cause of diarrhea in infants worldwide. A research priority of the World Health Organization is to develop oral rehydration solutions containing amino acids or other additives that will stimulate intestinal absorption more efficiently than the current glucose-based oral rehydration solutions. Glutamine is the principal metabolic fuel of the small bowel and a putative stimulator of mucosal repair. This report describes the transport response to mucosal L-glutamine following intestinal injury caused by porcine rotavirus. Peak symptoms and mucosal damage were observed 2-7 days after oral rotavirus inoculation. In vitro transport studies of the maximally injured region, the midjejunum (80% reduction in lactase), surprisingly, showed transport responses to L-glutamine (30 mmol/L) and L-alanine (30 mmol/L) that were similar qualitatively and quantitatively to those observed in control tissue. Subsequent application of mucosal D-glucose (30 mmol/L) caused additional stimulation of electrogenic Na+ transport, but the response to glucose was blunted (P less than 0.05) in the infected tissues. Glutamine and alanine enhanced Na+ absorption to a similar degree (2-2.5 muEq.cm-2.h-1), but glutamine stimulated equal amounts of electrogenic and electroneutral NaCl absorption, whereas alanine had no significant effect on net Cl- flux. Glutamine is a potentially useful substrate for investigation in oral rehydration solutions for infant diarrhea.

Alanine↗
PubMed1991

Microvillus inclusion disease. In vitro jejunal electrolyte transport.

Microvillus inclusion disease is an inherited intestinal brush border membrane defect that causes severe fluid and electrolyte malabsorption. In an infant with microvillus inclusion disease (confirmed by electron microscopic evaluation of rectal, jejunal, and gallbladder mucosae), basal stool output was massive (greater than 125 mL . kg-1 . day-1) and was not altered by treatment with clonidine or octreotide. A proximal jejunostomy with mucous fistula was placed, allowing separation of proximal from distal tract outputs (60 mL . kg-1 . day-1 and 100 mL . kg-1 . day-1, respectively). A 10-cm jejunal segment was excised during surgery and mounted in Ussing chambers for determination of transepithelial Na+ and Cl fluxes. Compared with intestine of normal infants, this infant's epithelium showed transmural conductance and unidirectional ion fluxes that were only 30% of normal. With respect to both Na+ and Cl, the excised jejunum was in a net secretory state. Theophylline (5 mmol/L) increased net Cl secretion slightly. In response to mucosal D-glucose (30 mmol/L), jejunal mucosal-to-serosal Na+ flux doubled. In the infant, glucose-electrolyte solution administered intrajejunally did not significantly change stool output, suggesting that all of the solution (40 mL/kg) was absorbed. Subtotal enterocolectomy, in theory, could have decreased purging by 66% in this infant with microvillus inclusion disease, but diarrhea would still have been significant.

Biological Transport, Active↗
PubMed1991

Hemorrhagic colitis and pseudomelanosis coli in ipecac ingestion by proxy.

This report describes a toddler with chronic diarrhea, vomiting, and hypotonia due to surreptitious administration of syrup of ipecac by his mother (Munchausen's syndrome by proxy). Several features of this case distinguish it from previous reports of chronic ipecac ingestion in childhood: the development of grossly bloody stools; radiologic, endoscopic, and biopsy evidence of a chronic moderate colitis resembling ulcerative colitis; and the histologic finding of pseudomelanosis coli, providing an important clue to toxic ingestion. The significance and possible mechanism for genesis of pseudomelanosis coli is discussed. This case emphasizes the variability in presentation and difficulty in diagnosing long-term ipecac ingestion by proxy. Ipecac toxicity should be considered in children with unexplained colitis and vomiting.

Biopsy↗
PubMed1990

Development of L-glutamine-stimulated electroneutral sodium absorption in piglet jejunum.

Glutamine is the primary metabolic fuel of the small intestine. To determine the effects of glutamine on intestinal electrolyte transport, piglet (3 days to 3 wk old) jejunum was bathed in Ussing chambers in a buffer containing 10 mM serosal glucose, and the effects of different concentrations of mucosal L-glutamine and D-glucose on short-circuit current and transmucosal Na+ and Cl- transport were measured. Resting jejunum secreted Na+ and Cl- in an electrogenic manner. In contrast to mucosal D-glucose (30 mM), which promoted electrogenic Na+ absorption (1.8 mueq.cm-2.h-1), mucosal L-glutamine (30 mM) stimulated both Na+ (2.7 mueq.cm-2.h-1) and Cl- (2.2 mueq.cm-2.h-1) absorption. This NaCl-absorptive jejunal response depended on the presence of both Na+ and Cl-, did not appear until animals were greater than 7 days of age, and was not observed with glucose, phenylalanine, or mannitol. Serosal, as well as mucosal, glutamine (30 mM) promoted electroneutral NaCl absorption. A small electrogenic Na(+)-absorptive response to L-glutamine was also observed. The effect of L-glutamine on jejunal NaCl transport resembles that of other metabolic fuels on colonic transport; its mechanism remains to be determined. We conclude that glutamine promotes electroneutral salt absorption in the small intestine.

Aging↗
PubMed1989

Diminished brush border membrane Na-dependent L-alanine transport in acute viral enteritis in piglets.

We studied sodium-dependent uptake of L-alanine into small intestinal brush border membrane vesicles (BBMV) isolated from piglets 40 h after infection with transmissible gastroenteritis (TGE) virus. Vesicles from TGE-infected pigs and uninfected litter-mate controls showed comparable degrees of enrichment and purity. In BBMV prepared by conventional techniques, [3H]L-alanine "overshoot" (peak uptake/equilibrium uptake) in the presence of a Na gradient was preserved in TGE BBMV, unlike [3H]D-glucose "overshoot," which was reduced. When these experiments were repeated using vesicles of greater purity, initial rates of Na-dependent L-alanine influx were reduced in BBMV from infected piglets under voltage clamped conditions with valinomycin. These studies demonstrate a specific amino acid transport defect in the small intestinal epithelium during acute viral diarrhea. They demonstrate too that brush border L-alanine-Na co-transport, although reduced, is present after viral damage, confirming previous studies that showed additive effects of amino acid and glucose on jejunal epithelial Na+ transport in transmissible gastroenteritis. Our findings support the concept that, in viral enteritis, oral rehydration solutions containing amino acid and glucose have a theoretical advantage over glucose electrolyte solutions because they facilitate brush border Na+ entry by two carrier mechanisms.

Acute Disease↗
PubMed1988

Effect of glucocorticoid on piglet jejunal mucosa during acute viral enteritis.

We measured the effect of pharmacological doses of glucocorticoid on piglet jejunal structure and function during acute viral diarrhea. Weaned piglets, infected experimentally with transmissible gastroenteritis virus, a coronavirus that induces a diarrheal illness similar to human rotavirus infection, received methylprednisolone (30 mg/kg) or saline intramuscularly at 48 and 72 h after infection; noninfected littermate controls were similarly injected with methylprednisolone. Animals were killed at 96 h, at the height of diarrhea, and jejunal epithelium was studied in vitro. Transmissible gastroenteritis, as expected, induced structural, enzyme, and Na transport abnormalities. Methylprednisolone did not affect small intestinal structure or function of noninfected control piglets. In transmissible gastroenteritis-infected piglets, jejunal villi were longer and glucose-facilitated Na absorption was greater after methylprednisolone than after saline treatment. Increased glucose stimulation of Na flux in vitro in the methylprednisolone-treated infected group was not attributable to enhanced Na+-K+-ATPase activity and occurred despite persistence of the virus within mucosal cells, shown by immunofluorescence microscopy. In this piglet model of viral diarrhea, early regeneration of absorptive surface that precedes recovery of disaccharidase function is accelerated by glucocorticoid therapy.

Acute Disease↗
PubMed1979

Brief reactive psychosis: a psychodynamic interpretation.

The diagnosis "brief reactive psychosis" leaves little implied in the way of etiology or treatment approach. Three case histories are presented to illustrate the term, followed by brief summaries of the major dynamics involved. The older diagnostic term "hysterical psychosis" is discussed, and a parallel is drawn between this form of brief reactive psychosis and others so that they may be psychodynamically understood and that treatment may be rationally based upon this model.

Adult↗
PubMed1977

Overwork.

Overwork, ie, working beyond one's endurance and recuperative capacities, may be a hazard in certain personality types engaged in open-ended occupations. Some persons appear to lack an inner "governor" and for various reasons ignore the commonplace signs that inform one of the need for rest or recreation. If they are engaged in occupations that do not have a finite workday, they may at times exceed their bodies' ability to recover. Clusters of symptoms may then develop, some of which may mimic serious physical ailments. Treatment depends on diagnosing the extent of illness and eliciting the underlying causes. Correction involves enforced rest, therapy that may vary from counseling to hospitalization and specialized treatment, but that must include the reeducation of the person to be aware of and make provision for his physical and emotional needs.

Adult↗
PubMed1976

Host-range properties of murine xenotropic and ecotropic type-C viruses.

Host-range properties of xenotropic (x-tropic) and ecotropic mouse type-C viruses were determined. NB-tropic viruses replicated only in mouse and rat cells, whereas x-tropic viruses, which do not exogenously infect mouse cells, grew in cells from various other mammalian species. Great variability in susceptibilities to x-tropic viruses was demonstrated in cells from heterologous species and in cells from a single species (human). Although rat cells were susceptible to both types of viruses, hamster cells were uniformly resistant. In addition, the x-tropic viruses crossed class barriers to infect cells of avian species but not insect, fish, or reptile cells.

Animals↗