Vicente P. Dinoso

Ultrastructural changes of the canine gastric mucosa after topical application of graded concentrations of ethanol

Changes in the fine structure of the gastric mucosa following exposure to graded concentrations of ethanol were studied in dogs. 300 ml of 12.5, 20, and 40%, vol/vol, were instilled intragastrically for 30 min. Mucosa from the midbody and midantrum along the greater curvature was examined by light and electron microscopy. Ethanol produced a gradation of changes in the surface epithelial cells and in the lamina propria without affecting the parietal cells and chief cells. 12.5% ethanol produced widened and irregular intercellular spaces while 20 and 40% disrupted the apical cell membrane with concomitant exudation of mucin into the gastric lumen. These changes were more severe after 40% ethanol. The tight junction between cells remained intact following exposure to the lower concentrations of ethanol, but focal separation of cell junctions was observed in severely damaged areas. Quantitation of protein, sodium, and potassium concentrations in the gastric contents revealed marked increases following exposure to ethanol which correlated with the concentration. These studies provide additional morphological data on the relationship between structural changes and functional abnormalities induced by agents which break the gastric mucosal barrier.

Characterization of a Hyperactive Segment at the Rectosigmoid Junction

During a study of intraluminal motor patterns of the colon and rectum, spontaneous wave activity of a continuous complex type was observed at the rectosigmoid junction in constipated subjects. To assess the frequency and characteristics of this hyperactive segment, 36 subjects with colonic motor disorders and 12 healthy controls were studied. Eighteen of 24 patients with constipation (75%) and 1 of 7 subjects with asymptomatic diverticulosis exhibited a persistent hyperactive segment at the rectosigmoid junction. Neither secretin nor cholecystokinin influenced the wave activity of the hyperactive segment. In contrast, atropine and glucagon inhibited markedly all wave activity and decreased the motility index of this segment significantly, suggesting overactivity of the muscarinic effector cells. It is concluded that a segmental area of overactivity exists at the rectosigmoid junction in most constipated subjects regardless of their underlying disorders.

Effects of ethanol on the gastric mucosa of the Heidenhain pouch of dogs.

The effect of ethanol on the mucosa of the Heidenhain pouch in dogs was studied by instilling ethanol in concentrations of 10, 20 and 40% using changes in ionic fluxes of an acid solution and mucosal alterations to measure the effects of ethanol. The instillation of 20 or 40% ethanol resulted in increased insorption of H+ and increased exorption of Na+ into the pouch lumen. Following the administration of 20 and 40% ethanol, the mucous layer and mucin content of the lining epithelial cells decreased markedly. Hourly bathing with the acid test solution aggravated the injury and induced bleeding, but hourly instillation of a buffer solution minimized the damage. Ionic fluxes returned to pre-ethanol levels 2 hr after 20% ethanol and 3–4 hr after 40% ethanol. Partial restoration of mucosal damage occurred in 4–6 hr and was complete in 24 hr.

Serial pH Changes in the Duodenal Bulb During Smoking

The effect of smoking on the pH of the duodenal bulb was studied in 10 normosecretors and 10 hypersecretors using a Beckman pH electrode. The pH was monitored during three study periods, basal, smoking, and postsmoking, of 1 hr each. The pH remained below 3.5 significantly longer during the smoking period compared to the basal period for both groups. The bulbar pH remained under 3.5 during the smoking period longer in the hypersecretor group compared to the normosecretor group (60 versus 20%). Hypersecretors who were smokers exhibited acidic bulbar pH values longer and more consistently than hypersecretor-nonsmokers during smoking. In 5 hypersecretors with data for both bulbar pH and bicarbonate output, inhibition of bicarbonate output during smoking was generally associated with acidic pH values in the bulb. These observations suggest that the association between cigarette smoking and peptic ulcer disease may be attributable to, in part, the persistently acidic pH values in the duodenal bulb during smoking. This study further suggests that the degree and the duration of acidification of the duodenal bulb during smoking are influenced by the secretory and the smoking status of the subject.

Effect of intraduodenal administration of essential amino acids and sodium oleate on motor activity of the sigmoid colon.

The effects of the intraduodenal administration of solutions of essential amino acids and 5% sodium oleate on motor activity of the sigmoid colon was studied in 11 normal subjects and in 1 patient with a previous antrectomy. A marked increase in motor activity was observed during administration of both solutions in all subjects, including the patient with antrectomy. Intravenous infusion of pentagastrin, in a dose of 0.6 μg per kg per hr, in 6 subjects did not influence motor activity of the sigmoid colon significantly. These observations suggest that the increased motor activity of the sigmoid colon, observed in response to exposure of the duodenum to essential amino acids and sodium oleate, could result from release of endogenous cholecystokinin.

Gastric and pancreatic function in patients with end-stage renal disease.

Gastroduodenal disease such as peptic ulcer and duodenitis is increased in patients with end-stage renal disease. Gastric hypersecretion of acid proposed as the underlying mechanism has been disputed because peptic ulcer has occurred even in those with normal or low gastric acid secretion. We studied the pancreatic exocrine secretion of bicarbonate (HCO3) and the concentration of plasma pepsinogens in addition to gastric acid secretion in 15 patients on chronic hemodialysis, 10 patients wih previous renal transplantation and compared them with 10 subjects without gastrointestinal or renal disease. We confirmed hypersecretion of gastric acid in renal disease. We confirmed hypersecretion of gastric acid in renal patients on chronic hemodialysis but not in transplant patients. In addition, we found basal but hyposecretion of HCO3 and hyperpepsinogenemia in both renal groups. These observations suggest that the high incidence of gastroduodenal disease in end-stage renal disease might, in part, be due to the simultaneous occurrence of gastric acid hypersecretion, basal hyposecretion of HCO3 by the pancreas, and hyperpepsinogenemia.