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The tolerance of healthy subjects to increasing rates of tube feeding was studied to better understand the etiology of diarrhea among tube-fed patients. Five volunteers were fed Osmolite HN by continuous duodenal infusion beginning at 314 kJ (75 kcal) [multiplied by kg body [wt.sup.-1] [multiplied by] [d.sup.-1] and progressing each until no longer tolerated. The five subjects were able to tolerate maximum 24-h infusions of 331-511 kJ [multiplied by] [kg.sup.-1] [multiplied by] [d.sup.-1] (198-340 mL/h). Diarrhea developed in only three subjects. Compared with nondiarrheal stools, the high-speed supernatant of the diarrheal stools had significantly higher concentrations of magnesium (192 [+ or -] mmol/L vs 139 [+ or -] 17 mmol/L, P = 0.005), lower concentrations of potassium and phosphorus, and similar concentrations of calcium. The mean carbohydrate, fat, and nitrogen contents were not significantly different. We conclude that normal adult males are remarkable tolerant to duodenal infusion of this typical, isotonic tube-feeding product. The diarrhea that occurred in three of the volunteers at very high infusion rates appeared to be osmotic and attributable predominantly to magnesium. Am J Clin Nutr 1993;57;73-80.

Total body water, body fat, body cell mass (BCM), extracellular mass (ECM), and the ECM-BCM ratio by impedance analysis were determined in 193 human immunodeficiency virus (HIV)-infected patients and 340 control subjects. Walter Reed (WR) classification was WR 2 in 26, WR 3-5 in 85, and WR 6 in 82 patients. Whereas resistance was increased, reactance and the phase angle were significantly reduced in all patient groups. Neither body weight nor body mass index (BMI) was affected in WR 2 patients, but BCM was reduced (31.9 [+ or -] 4.3 vs 35.8 [+ or -] 7.3 kg, P < 0.007) and ECM (31.2 [ + or -] 4.4 vs 28.8 [+ or - ] 3.8 kg) as well as ECM-BCM ratio increased (0.99 [+ or -] 0.14 vs 0.83 [+ or -] 0.16, P < 0.001). In contrast to WR classification, diarrhea did not correspond with malnutrition. A loss of BCM (malnutrition) occurred already in otherwise symptomless HIV-infected patients (WR 2). This effect can be measured by tetrapolar impedence analysis but not by body weight or BMI. Am J Clin Nutr 1993;57:15-9.

Diarrhea, a major health problem worldwide, is both a sign and a symptom. As a symptom, diarrhea has been described as an increase in stool frequency, an increase in stool volume, and/or a decrease in stool consistency. As a sign, diarrhea is characterized by an increase in stool water excretion to greater than 150 to 200 ml every 24 hours. Four mechanisms that may be responsible for the alterations in fluid and electrolyte movement associated with diarrhea are increased luminal osmolality, decreased fluid absorption, increased intestinal secretion, and altered intestinal motility. Specific pathogenic mechanisms for acute infectious diarrhea include tissue invasion, enterotoxin production, and adhesion of infectious agents to epithelial cells. Antidiarrheal agents remove secretagogues from the intestinal tract, stimulate fluid absorption, and inhibit electrolyte movement., Normal bowel function is characterized by the production of bowel movements (stools) ranging from two or three times a day to two or three times a week. When food passes through the gastrointestinal (GI) tract, it is mixed with water, and most of this water is reabsorbed in the large intestine. Problems affecting this organ can lead to the production of diarrhea. Diarrhea is defined as the frequent passage of unformed, watery stools and is a major health problem in third world countries. It can lead to severe dehydration and death, especially in infants, when not treated. Causative factors of diarrhea include: an increase in the ability of the intestinal contents to draw water into the GI tract, a decrease in the amount of water that is re-absorbed from the intestinal contents, an increase in intestinal movement, and an increase in the amount of water secreted by the intestines. All of these factors increase the water content of stool. Diarrhea lasting only a few days is often due to bacterial infection, which increases intestinal water secretion. Bacteria cause diarrhea by attaching directly onto the cells that line the intestines and by secreting toxins into the GI tract. Anti-diarrheal medications work largely by removing the offending agent from the intestines or by inhibiting intestinal movement. The latter method slows the transit time for food through the intestine, and leads to an increase in water reabsorption. As other causes of diarrhea are uncovered and understood, additional effective agents may be developed to help treat this disorder. (Consumer Summary produced by Reliance Medical Information, Inc.)

Background: Persons infected with human immunodeficiency virus (HIV) are at increased risk for diarrhea and enteric infections. We studied (1) the epidemiology of enteric pathogens associated with diarrhea, (2) the diagnostic yield of stool examination and endoscopic evaluation, (3) risks to develop diarrhea, and (4) the impact of diarrhea on patients' survival. Methods: A total of 1933 participants in the Swiss HIV Cohort Study were prospectively followed up for a median of 25.5 months. A total of 560 diarrheal episodes were evaluated by standardized stool examination. Endoscopic evaluation was performed in 25% of patients with chronic diarrhea. Results: The incidence of diarrhea was 14.2 per 100 person-years (95% confidence interval, 13.0-15.4). Among patients with CD4 cell counts below 0.05 X [10.sup.9]/L, the probability to develop diarrhea within 1, 2, and 3 years was 48.5%, 74.3%, and 95.6%, respectively. The risk to develop diarrhea was increased among patients with severe immunodeficiency, homosexual men, and patients taking antiretroviral therapy. Pneumocystis carinii chemoprophylaxis did not reduce the risk of diarrhea. Diarrhea was an independent negative predictor of survival. Enteric pathogens were detected in 16.5% of 212 acute diarrheal episodes and in 46% of 348 chronic diarrheal episodes. The sensitivity of histological and stool examination was similar except for the diagnosis of intestinal cytomegalovirus infection and leishmaniasis, which required invasive evaluation. Conclusions: Intestinal infections were diagnosed in less than 50% of chronic diarrheal episodes. The prevalence of enteric pathogens tended to decrease during the observation period, possibly because of improved antiretroviral therapy. Endoscopic evaluation did not improve the diagnostic yield compared with stool examination except for the diagnosis of cytomegalovirus enteritis and leishmaniasis. Arch Intern Med. 1999;159:1473-1480