Secretory pathways in Salmonella Typhimurium-induced fluid accumulation in the porcine small intestine.

The involvement of 5-hydroxytryptamine (5-HT) and 5-HT3 receptors and prostaglandin E2 (PGE2) in Salmonella Typhimurium-induced fluid accumulation in the porcine small intestine was investigated. Salmonella Typhimurium (10(8) and 10(10) cfu) and cholera toxin (CT; 20 microg) were instilled for 8 and 11 h in ligated loops in the porcine jejunum and ileum. Fluid accumulation and concentrations of Na+, K+, Cl-, 5-HT and PGE2 in the fluid accumulated in the loops were measured. The fluid accumulation was also measured when Salmonella Typhimurium (10(10) cfu) and CT (20 microg) were instilled for 8 h in ligated loops in jejunum and ileum in pigs given subcutaneous injections of saline or the 5-HT3 receptor antagonist ondansetron (200 microg/kg). Salmonella Typhimurium (10(10) cfu) and CT both induced fluid accumulation in jejunum and ileum after 8 and 11 h. Both treatments also induced an increase in luminal release of 5-HT and PGE2. The accumulated fluid was iso-osmotic and hyperosmotic in CT- and Salmonella Typhimurium-treated loops, respectively. Ondansetron reduced the Typhimurium-induced fluid accumulation in both jejunum and ileum by c. 40%, while it failed to reduce the response to CT. These results demonstrate that 5-HT and PGE2 are released and 5-HT3 receptors activated in the secretory pathway of Typhimurium in the porcine small intestine.

In vitro maintenance of Schistosoma japonicum and surgical transfer from donor to naïve recipient pigs.

An objective of this study was to find a culture medium and a temperature range suitable for in vitro maintenance of adult Schistosoma japonicum during surgical transplantation experiments. Adult S. japonicum were cultivated in four different media (NCTC 135, NCTC 109, RPMI 1640 and 0.85% physiological saline) supplemented with 10% heat-inactivated normal pig serum (hiNPS) at either 4 degrees C, 22-25 degrees C (room temperature) or 37 degrees C. Based on survival and morphologic evaluation, NCTC 135 at room temperature was found to be the best medium/temperature combination for maintenance of worms. An additional objective was to develop a method for transplanting adult S. japonicum from experimentally infected donor pigs to naïve recipient pigs. Six Landrace/Yorkshire crossbred pigs were used as donors to supply worms for two recipient pigs. Worms for transplantation were obtained by perfusion of the mesenteric veins of the donor pigs and maintained for a maximum of 3 h in NCTC 135 + 10% hiNPS at room temperature. A total of 148 and 132 worms were surgically transferred by way of an infusion tube into caecal veins of the two recipients. Six weeks after transplantation, 14% and 36% of the transferred worms were recovered by perfusion and subsequent manual inspection of the mesenteric veins of the two recipient pigs, respectively. The successful results suggest that surgical transfer of S. japonicum worms from donor to naïve recipient pigs may be useful for future studies on population genetics, dynamics and regulation in the pig/S. japonicum model.

Experimental transfer of Ascaris suum from donor pigs to helminth naive pigs.

The difficulties in experimentally establishing patent intestinal infections with the pig large roundworm Ascaris suum make transfer of adult or larval stages a potentially important method of inducing this infection. Adult worms and 10-day-old larvae were transferred by stomach tube to untreated pigs and pigs treated with the gastric acid pump inhibitor omeprazole, as well as surgically directly into the small intestine of pigs. Transfer of adult worms resulted in patent infections with comparable worm survival rates in all 3 recipient groups but with a nonsignificant decrease in egg production after transfer to untreated pigs. Thus, it is possible with oral transfer of adult worms to achieve infections with more or less known numbers and sexes of the parasites, as well as producing patent infections in hosts that have never experienced a hepato-tracheal migration. Whereas the orally transferred 10-day-old L3/L4 larvae did not establish well, surgical transfer of larvae to helminth-naive recipient pigs resulted in high recovery rates 1 wk after transfer in 3 out of 5 pigs.

Critical differences of clinical chemical components in blood from Red Danish dairy cows based on weekly measurements.

The critical difference, which may help to judge whether the difference between two consecutive analytical results may be safely ascribed to natural variation or not, was calculated for 12 clinical chemical components determined in blood samples collected once a week for 5 consecutive weeks from 19 clinically healthy Red Danish dairy cows. For each clinical chemical component, the total variance of the analytical results was divided into the component of variance between cows (S2Inter), the component of variance for weeks within cows (S2Intra) and the component of variance for measurements (S2Anal) using nested analysis of variance. The critical difference calculated in absolute values from S2Intra and S2Anal was 0.15 mu kat per 1 for alanine aminotransferase, 0.55 mu kat per 1 for aspartate aminotransferase, 0.57 mu kat per 1 for alkaline phosphatase, 0.14 mu kat per 1 for gamma-glutamyltransferase, 1.95 mu kat per 1 for creatine kinase, 2.23 mmol per 1 for urea, 22 mu mol per 1 for creatinine, 2.4 g per 1 for albumin, 10.0 g per 1 for serum protein Total, 0.71 mmol per 1 for glucose, 0.54 mmol per 1 for calcium and 0.25 mmol per 1 for magnesium. These critical differences may be used as guidelines to evaluate the difference between two consecutive analytical results in cows. However, the analytical results should not be assessed by the critical differences alone, but should also be compared with the corresponding reference intervals.

Critical differences of clinical-chemical parameters in blood from Red Danish dairy cows.

The purpose of the present study was to calculate the critical differences between two analytical results for 23 routinely used bovine clinical-chemical parameters. The critical difference can be used to judge whether the difference between two consecutive analytical results from the same animal is due to natural variation or not. From 20 cows, blood samples were collected once daily for five days, and the interindividual variance, the intra-individual variance, and the analytical variance were calculated using nested analysis of variance. The critical difference both in absolute values and in percentages was calculated from these variances. The main conclusions were that the critical difference in percentages was in general between 10 and 40 per cent but varied from 10.6 per cent for sodium to 280.2 per cent for lactate and that the analytical variation was generally in accordance with accepted standards, although the analytical variation for alkaline phosphatase, total serum protein, urea and fructosamine should be improved.

Critical difference of some bovine haematological parameters.

The purpose of the present study was to calculate the critical difference between 2 analytical results for the red blood cell count (RBC), the white blood cell count (WBC), the haemoglobin concentration (Hb), and the haematocrit (PCV) in blood from Red Danish Dairy cows. The critical difference can help to judge whether the difference between 2 consecutive analytical results from the same animal may be safely ascribed to natural variation or not. To calculate the critical differences, blood samples from 20 clinically healthy lactating cows were collected once daily for 5 consecutive days. The total variance of the analytical results was divided into the component of variance between cows (S2Inter), the component of variance for days within cows (S2Intra), and the component of variance for measurements (S2Anal) using nested analysis of variance. The critical difference was then calculated from S2Intra and S2Anal as 0.61 x 10(12)/l for RBC, 2.2 x 10(9)/l for WBC, 0.79 mmol/l for Hb, and 0.07 for PCV. The critical differences may be used as guidelines to indicate potentially important changes in the parameters. However, the analytical results should not be assessed by the critical differences alone, but should also be compared to the corresponding reference intervals.

Effect of age on the secretory capacity of pig small intestine in vivo and in vitro.

The effect of age on the secretory response of pig small intestine to in vivo challenge by cholera toxin (CT) was investigated. The small intestine of 14-day-old pigs was more sensitive to CT challenge than that of 14-wk-old animals. In the 14-day jejunum CT-induced fluid secretion was five times that observed in the 14-wk tissue. Similarly, the 14-day ileum produced a fourfold higher secretion than the 14-wk ileum, although the magnitude of ileal secretion was markedly lower than that observed in the jejunum at the same CT dose. This reduced response to CT with age was not due to a reduced secretory capacity of the tissue, since supramaximal doses of prostaglandin E2 and theophylline induced a similar response in tissue from both age groups in vitro. We conclude that these results are consistent with the hypothesis that an antisecretory factor, which naturally inhibits fluid losses in enterotoxigenic diarrhea, is produced in older animals.

Effect of ondansetron on Salmonella typhimurium-induced net fluid accumulation in the pig jejunum in vivo.

Two major pathophysiological mechanisms explaining the diarrhoea induced by Salmonella typhimurium have been suggested to be: (a) invasion of the intestine by the bacteria, and (b) an enterotoxin resembling Vibrio cholerae toxin. Cholera toxin is a potent secretagogue in pig small intestine and induces secretion partly by activating 5-hydroxytryptamine receptors, following release of 5-hydroxytryptamine. Ondansetron is a selective 5-hydroxytryptamine-3 receptor antagonist, which reduces the cholera toxin-evoked fluid accumulation in pig jejunum. The aim of this study was to investigate the effect of ondansetron on Salmonella typhimurium-induced fluid accumulation in ligated loops of pig jejunum in vivo. 10(10) colony-forming units of the bacteria was injected into loops and incubated for 8 hr. 200 mg x kg-1 ondansetron given subcutaneously reduced the Salmonella typhimurium-induced fluid accumulation by about 40%. This results suggests the involvement of 5-hydroxytryptamine and 5-hydroxytryptamine-3 receptors in Salmonella typhimurium-induced diarrhoea.

Secretory response to cholera toxin in the porcine jejunum under different types of general anaesthesia.

Investigations of intestinal secretion are often performed under anaesthesia. This study evaluates the influence of anaesthetic agents on the intestinal secretion induced by cholera toxin (CT) in the pig. CT was instilled for 4 h in ligated jejunal loops under anaesthesia with halothane, saffan, alpha-chloralose, or propofol. Cardiovascular parameters, blood gas data, plasma cortisol levels, net fluid accumulation, intraluminal mediators (serotonin (5-HT), prostaglandin E2 (PGE2)) and electrolyte concentrations in the accumulated fluid were determined. The systolic blood pressure and heart rate was highest for saffan-anaesthetized pigs (blood pressure: saffan > alpha-chloralose > propofol = halothane; heart rate: saffan > alpha-chloralose = propofol = halothane), while blood gases and cortisol levels were within the same range. CT induced a dose-dependent fluid accumulation under all four anaesthetics. The fluid accumulation was significantly higher in pigs treated with saffan, alpha-chloralose and propofol than in halothane-treated pigs (saffan = alpha-chloralose > propofol > halothane). There was no significant difference in electrolyte concentrations in the accumulated fluid or in the luminal content of 5-HT and PGE2 between anaesthetics. The results demonstrate that anaesthetic agents profoundly influence the secretory response in the small intestine and indicate the importance of the choice of anaesthetic in this type of experiment.