Interactions between gastric volume and duodenal nutrients in the control of liquid gastric emptying.
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We examined the relationships between gastric volume and duodenal glucose load in the regulation of gastric emptying in adult male rhesus monkeys. Intragastric glucose loads (0.125 g/ml) of volumes ranging from 150 to 375 ml empty from the stomach at the same rate from 20 to 120 min. However, to achieve these equivalent emptying rates, progressively larger volumes were emptied in the initial 20 min with increasing gastric volume. Duodenal glucose infusions dose dependently inhibited the 10-min emptying of various volumes of intragastric saline. Although increasing gastric volume resulted in increased emptying, duodenal glucose right-shifted the relationship between initial gastric volume and volume emptied. These data demonstrate that liquid nutrient gastric emptying represents an interaction between gastric volume and nutrient-induced duodenal feedback. For controlled duodenal caloric delivery rates to be established, sufficient nutrient emptying must occur to increase the magnitude of duodenal feedback to withhold a given gastric volume. (+info)
A comparison of the effects of dietary cellulose and fermentable galacto-oligosaccharide, in a rat model of colorectal carcinogenesis: fermentable fibre confers greater protection than non-fermentable fibre in both high and low fat backgrounds.
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The objective of this experiment was to compare the effects of diets with either a non-fermentable fibre source (cellulose) or a fermentable fibre source [galacto-oligosaccharide (GOS)], combined with different levels of dietary fat, on the development of colorectal cancer. Male Wistar rats were fed AIN76-based diets with either a low or high level of cellulose, or a low or high level of GOS, for 9 months. The fat content of the diets was low, medium or high. All rats were treated with 1,2-dimethylhydrazine to induce colorectal tumours. Generally, the tumour incidence increased with increasing fat content in the diet. Despite marked faeces bulking, dietary cellulose either had no effect or an enhancing effect on the formation of colorectal tumours in general, although the development of carcinomas was decreased. GOS appeared to be highly protective against the development of colorectal tumours, as was demonstrated by an inhibitory effect on tumour incidence, multiplicity and size, regardless of the fat content of the diet. Neither fibre source influenced the bromodeoxyuridine labelling index determined in colon crypts or tumours. In animals fed high-GOS diets, the caecal content was significantly increased in weight and significantly decreased in pH. It was concluded that tumorigenesis was enhanced by increased fat content of the diet, and that the diets containing fermentable GOS conferred a greater protection against colorectal cancer than did the diets containing non-fermentable cellulose. (+info)
Part of quercetin absorbed in the small intestine is conjugated and further secreted in the intestinal lumen.
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Rutin and quercetin absorption and metabolism were investigated in rats after in situ perfusion of jejunum plus ileum (15 nmol/min). In contrast to rutin, a high proportion of quercetin (two-thirds) disappeared during perfusion, reflecting extensive transfer into the intestinal wall. Net quercetin absorption was not complete (2.1 nmol/min), inasmuch as 52% were reexcreted in the lumen as conjugated derivatives (7.7 nmol/min). Enterohepatic recycling contribution of flavonoids was excluded by catheterization of the biliary duct before perfusion. After a 30-min perfusion period, 0.71 microM of quercetin equivalents were detected in plasma, reflecting a significant absorption from the small intestine. The differential hydrolysis of effluent samples by glucuronidase and/or sulfatase indicates that the conjugated forms released in the lumen were 1) glucuronidated derivatives of quercetin and of its methoxylated forms (64%) and 2) sulfated form of quercetin (36%). In vitro quercetin glucuronides synthetized using jejunal and ileal microsomal fractions were similar to those recovered in the effluent of perfusion. These data suggest that glucuronidation and sulfatation take place in intestinal cells, whereas no glucurono-sulfoconjugates could be detected in the effluent. The present work shows that a rapid quercetin absorption in the small intestine is very effective together with its active conjugation in intestinal cells. (+info)
Typing Listeria monocytogenes by random amplified polymorphic DNA (RAPD) fingerprinting.
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Twenty epidemiologically unrelated Listeria monocytogenes strains isolated from different animals, locations and on different dates in Japan were classified into 18 types by the random amplified polymorphic DNA (RAPD) fingerprinting technique with four primers. Further, seven epidemiologically related L. monocytogenes strains isolated from raw milk and a bulk tank on a dairy farm represented the same RAPD type suggesting that they were all of the same origin. Therefore, RAPD-polymerase chain reaction (PCR) analysis, which is rapid, simple and inexpensive to perform, can be used in surveys as a convenient epidemiological technique. (+info)
An esophagogastroduodenal anastomosis model for esophageal adenocarcinogenesis in rats and enhancement by iron overload.
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The aim of this study is to establish a good animal model for esophageal adenocarcinoma (EAC) and to test the hypothesis that iron over-nutrition enhances EAC formation. With rats, esophagogastroduodenal anastomosis (EGDA) was accomplished by anastomosing the duodenum to the gastroesophageal junction. Iron supplementation was given by i.p. injection of iron dextran (4 mg Fe/kg/week). This model mimics the development of human EAC by introducing mixed reflux of gastric and duodenal contents. At 40 weeks after surgery, the body weight, food intake, hemoglobin, total serum iron, transferrin saturation, serum albumin, and plasma levels of alpha-tocopherol, gamma-tocopherol and retinol of the EGDA rats were not significantly different from those of the non-operated controls. The animals generally had only mild esophagitis, except that the area surrounding the anastomosis opening had more severe esophagitis. Columnar-lined esophagus (CLE), CLE with dysplasia, and EAC were diagnosed in 53.5, 34.9 and 25.6%, respectively, of the 43 rats. Intraperitoneal iron supplementation significantly enhanced esophageal lesions with CLE, CLE with dysplasia, and EAC to 78.0, 53. 7 and 53.7%, respectively, of the 41 rats. All the tumors were well-differentiated mucinous adenocarcinomas at the squamocolumnar junction area, where most iron deposition was observed. EGDA avoids nutritional problems seen in other animal models for EAC. We believe that direct anastomosis of squamous epithelium to columnar epithelium and mixed reflux of gastric and duodenal contents lead to the formation of CLE and EAC. With this model, we demonstrated that iron supplementation significantly enhanced EAC formation, suggesting that iron over-nutrition could also be a risk factor for human EAC. (+info)
H(+)/solute-induced intracellular acidification leads to selective activation of apical Na(+)/H(+) exchange in human intestinal epithelial cells.
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The intestinal absorption of many nutrients and drug molecules is mediated by ion-driven transport mechanisms in the intestinal enterocyte plasma membrane. Clearly, the establishment and maintenance of the driving forces - transepithelial ion gradients - are vital for maximum nutrient absorption. The purpose of this study was to determine the nature of intracellular pH (pH(i)) regulation in response to H(+)-coupled transport at the apical membrane of human intestinal epithelial Caco-2 cells. Using isoform-specific primers, mRNA transcripts of the Na(+)/H(+) exchangers NHE1, NHE2, and NHE3 were detected by RT-PCR, and identities were confirmed by sequencing. The functional profile of Na(+)/H(+) exchange was determined by a combination of pH(i), (22)Na(+) influx, and EIPA inhibition experiments. Functional NHE1 and NHE3 activities were identified at the basolateral and apical membranes, respectively. H(+)/solute-induced acidification (using glycylsarcosine or beta-alanine) led to Na(+)-dependent, EIPA-inhibitable pH(i) recovery or EIPA-inhibitable (22)Na(+) influx at the apical membrane only. Selective activation of apical (but not basolateral) Na(+)/H(+) exchange by H(+)/solute cotransport demonstrates that coordinated activity of H(+)/solute symport with apical Na(+)/H(+) exchange optimizes the efficient absorption of nutrients and Na(+), while maintaining pH(i) and the ion gradients involved in driving transport. (+info)
Technical note: a device for obtaining time-integrated samples of ruminal fluid.
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A device was adapted to allow for time-integrated sampling of fluid from the rumen via a cannula. The sampler consisted of a cup-shaped ceramic filter positioned in the ventral rumen of a cannulated cow and attached to a tube through which fluid entering the filter was removed continuously using a peristaltic pump. Rate of ruminal fluid removal using the device was monitored over two 36-h periods (at 6-h intervals) and was not affected (P > .05) by time, indicating that the system was not susceptible to clogging during this period. Two cows having ad libitum access to a totally mixed ration were used in a split-block design to evaluate the utility of the system for obtaining time-integrated samples of ruminal fluid. Ruminal fluid VFA concentration and pattern in samples collected in two replicated 8-h periods by the time-integrated sampler (at 1-h intervals) were compared with composite samples collected using a conventional suction-strainer device (at 30-min intervals). Each 8-h collection period started 2 h before or 6 h after feeding. Results indicated that total VFA concentration was not affected (P > .05) by the sampling method. Volatile fatty acid patterns were likewise unaffected (P > .05) except that acetate was 2.5% higher (P < .05) in samples collected 2 h before feeding and valerate was 5% higher (P < .05) in samples collected 6 h after feeding by the suction-strainer device. Although significant, these differences were not considered physiologically important. We concluded that use of the ceramic filter improved the sampling of ruminal fluid by simplifying the technique and allowing time-integrated samples to be obtained. (+info)
Acute zolpidem overdose--report of two cases.
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This report describes two cases of acute zolpidem overdose. The decedent in the first case was a 36-year-old female found dead in bed in her secured home. She had a history of psychiatric illness, including paranoid disorder, depression with panic episodes, and post-traumatic stress disorder. She was treated with risperidone and sertraline. Nine months prior to her death, the decedent was also prescribed zolpidem (Ambien). The postmortem examination revealed white foam within the larynx and upper trachea, which is indicative of pulmonary edema. Toxicological analyses of the urine showed the presence of caffeine, risperidone, and zolpidem. Subsequent quantitation of postmortem iliac serum revealed 5.6 microg/L of 9-hydroxyrisperidone and the following zolpidem concentrations: blood (subclavian), 4.5 mg/L; blood (iliac), 7.7 mg/L; vitreous humor, 1.6 mg/L; bile, 8.9 mg/L; urine, 1.2 mg/L; liver, 22.6 mg/kg; and gastric contents, 42 mg. The second case involved a 58-year old female, also found dead in bed, with white foam around her mouth. The decedent had a 25-year history of hypertension and mental illness--manic depression and schizophrenia. She was medicated with carbamazepine, naproxen, risperidone, and zolpidem. The postmortem examination revealed cardiomegaly, pulmonary edema, hepatomegaly, mild coronary atherosclerosis, and no signs of trauma. Toxicological analyses of the urine showed the presence of zolpidem and carbamazepine and metabolite. Zolpidem concentrations were as follows: blood (iliac), 1.6 mg/L; vitreous humor, 0.52 mg/L; bile, 2.6 mg/L; liver, 12 mg/kg; and gastric contents, 0.9 mg. The zolpidem blood concentrations of these cases are consistent with those of the previously published fatalities. The blood/vitreous humor ratios of zolpidem were 2.81 (subclavian) and 4.81 (iliac) in the first case and 3.08 (iliac) in the second case. These ratios, along with the sampling times of blood and vitreous humor for both cases, are not conclusive to indicate a definitive presence or absence of postmortem drug redistribution of zolpidem. The cause of death for both cases was determined to be acute zolpidem overdose, and manner of death was suicide. (+info)