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 47,337 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A description of the different stages of Trypanosoma (M.) melophagium in different regions of the gut of the sheep ked (Melophagus ovinus) as observed by the SEM is presented. The extensive pile carpet or palisade colonization of the midgut and pylorus is described. The method of attachment and the relationship of the parasites to the microvilli in the midgut and the cuticle of the pylorus and ileum observed by other methods are confirmed. The micro-structure of the surfaces themselves in the regions of the gut to which parasites attach are described. The use of the technique for the study of other similar systems is discussed.
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PMID:Trypanosoma (megatrypanum) melophagium in the sheep ked, Melophagus ovinus. A scanning electron microscope (SEM) study of the parasites and the insect gut wall surfaces. 3 51

RDEC-1 is a piliated strain of Escherichia coli that was isolated from and produces diarrhea in rabbits without invading the mucosa or synthesizing one of the classical enterotoxins. Previous histological and fluorescent-antibody studies of RDEC-1 diarrhea revealed an acute inflammatory response and large numbers of RDEC-1 associated with (adhering to) the mucosal surface of the ileum, cecum, and colon. The purpose of the present investigation was to further elucidate the histopathology by scanning (SEM) and transmission (TEM) electron microscopy. SEM revealed aggregates of bacteria on the surface of the gut; their distribution was patchy in the ileum and diffuse in the cecum and colon. Bacteria were in contact with each other and appeared to be closely associated with the epithelial surface. TEM showed that the brush border region of the epithelial cells was found to be in varying stages of degeneration, and the bacteria could not be seen adhering to the mucosal cells unless the brush border was absent. Bacteria were in close contact only with epithelial cells that had lost their brush border. The space between the bacteria and the epithelial cells was 11 nm, and it appeared to be filled, in most cases, with densely stained material. This E. coli rarely penetrated epithelial cells, but when it did; it was found in the supranuclear region and never reached the lamina propria. From previous and present studies, it seems probable that RDEC-1 produces diarrhea in rabbits by a mechanism that may be cytotoxic and differs from the classic mechanisms by which E. coli produces diarrhea.
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PMID:Scanning and transmission electron microscopic study of Escherichia coli O15 (RDEC-1) enteric infection in rabbits. 34 19

The effects of various hexoses upon immunoreactive insulin (IRI) secretion, glucose disposal, and gastric inhibitory polypeptide (GIP) release have been compared in 10 normal nonobese men. Rapid iv infusion (0.5 g/kg in 3 min) of D-mannose resulted in significant ITI release, the peak levels approaching those after D-glucose infusion. D-Galactose, however, was ineffective. The 60-min urine excretions of mannose, galactose, and glucose were 35 +/- 7%, 16 +/- 4%, and 5.5 +/- 0.7% (mean +/- SEM) of the administered dose, respectively. All subjects also received 50 g oral glucose, mannose, galactose, and fructose on different days, each followed by an iv glucose infusion 30 min later. The ingestion of glucose or galactose resulted in a similar increment of GIP (P less than 0.01), followed by a similar increment in the IRI response to iv glucose. Furthermore, the glucose disposal rate increased 2.5-fold compared to that after iv glucose alone (P less than 0.001). However, oral msnnose or oral fructose caused no significant GIP release, yet the IRI response to a subsequent iv glucose load was moderately augmented after oral mannose or oral fructose when compared to iv glucose alone. In addition, there was a similar enhancement of glucose disposal of the iv glucose load after both oral mannose and oral fructose (P less than 0.01). From these studies we conclude that 1) galactose does not elicit IRI secretion per se, yet, like glucose, potentiates GIP and IRI secretion; 2) mannose, despite weak transport across gut or kidney, evokes significant betacytotropic effects; and 3) mannose- and fructose-induced enhancement of glucose disposal might be mediated by a factor(s) other than GIP.
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PMID:Metabolic effects of glucose, mannose, galactose, and fructose in man. 47 51

Somatostatin-like immunoreactivity (SLI) has been demonstrated by radioimmunoassay (RIA) in rat serum using an antiserum specific for somatostatin and cross-reacting maximally with the biologically important area on the peptide. The RIA has a sensitivity of 35 pg/ml. SLI dilutes in parallel with synthetic somatostatin standard in the RIA and shows characteristics similar to synthetic somatostatin on Sephadex G-25 (f) gel chromatography eluting largely as a single peak with 1 M acetic acid. Significant regional differences in serum SLI are present. A positive gradient was found in paired samples from aorta (mean+/-SEM, 0.304+/-0.024 ng/ml) and portal vein (0.495+/-0.047 ng/ml) consistent with the known presence of somatostatin in gut and pancreas, and a negative gradient was noted between paired samples from portal vein (0.523+/-0.076 ng/ml) and hepatic vein (0.290+/-0.048 ng/ml) indicating hepatic clearance. No significant differences were demonstrated between aorta and confluence of cerebral venous sinuses or between aorta and inferior vena cava (IVC). After intragastric glucose, a significant and marked elevation of portal SLI was observed, maximal at 5 min (0.416+/-0.137 vs. 1.55+/-0.30 ng/ml at 5 min). A significant biphasic elevation of portal SLI also occurred after intravenous glucose. After both routes of glucose administration, the patterns of portal SLI followed closely those of portal glucose and insulin. By contrast, IVC SLI failed to reflect these changes.Thus, SLI in the rat shows chromatographic similarity with synthetic somatostatin. Regional differences in serum levels are marked; the highest concentrations being found in the portal venous effluent of pancreas and gut. Furthermore, glucose causes elevation of portal SLI in a pattern similar to portal insulin and glucose and without concomitant elevation in IVC. This differential elevation of SLI after glucose is consistent with a hormonal action within the portal system as a direct effect of somatostatin on the liver has previously been demonstrated. In addition, the liver is important in the clearance of portal SLI, possibly to prevent extraportal effects in response to gut and pancreatic stimulation. Finally, it is clear that regional sampling of serum for SLI measurement may be critical in the investigation of the putative physiological roles for somatostatin.
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PMID:Somatostatin-like immunoreactivity in rat blood. Characterization, regional differences, and responses to oral and intravenous glucose. 65 2

The present investigation was designed to quantitatively assess the possible influence of countercurrent exchange on passive absorption from the small intestine of the dog. Villus blood flow was measured with a modification of the microsphere method. Simultaneously, the absorption from the gut lumen of five diffusible gases (H2, He, CH4, 133Xe, and CO) was determined. Villus blood flow averaged 0.247 +/- 0.03 (SEM) ml/min per g. The observed absorption of H2, He, CH4, and 133Xe was only 16.2 +/- 1.8, 12.8 +/- 2.3, 12.0 +/- 1.8, and 15.8 +/- 1.4 %, respectively, of what this villus blood flow could carry away if it reached perfect equilibrium with the luminal gases. This low absorption rate could result from diffusion limitation to absorption or countercurrent exchange. The diffusive permeability of the barrier seperating the luminal gases and villus blood flow was assessed by measuring the absorption rate of CO. Because absorbed CO binds tightly to hemoglobin, it cannot exchange, and when present in low concentrations its uptake is entirely diffusion limited. Knowledge of the diffusion rate through tissue of the unbound gases relative to that of CO made it possible to calculate the degree to which each of the unbound gases should equilibrate with villus tip blood. The percentage equilibration between lumen and blood at the villus tip for H2, He, CH4, and 133Xe was 99.7, 99.9, 75.6, and 36.0% , respectively. Each of these values greatly exceeded the percentage equilibration of blood leaving the villus (calculated from the observed absorption rate and villus blood flow) and indicated an exchange of 83.8, 87.2, 84.1, and 56.1% of initially absorbed H2, He, CH4, and 133Xe. This result is in accord with theoretical calculations which suggest that countercurrent exchange should be exceedingly efficient in the dog. The striking effect of countercurrent exchange on passive absorption in the dog differs from our previous studies in the rabbit where no exchange was demonstrated. This marked species difference may result from anatomical differences in villus architecture. The dog has long, densely packed villi while the rabbit has broad, widely spaced villi. In the dog, only the villus tips may equilibrate with the lumen, hence a countercurrent gradient may be established in the villus. The entire villus of the rabbit may equilibrate with the lumen and no gradient for countercurrent exchange can therefore be established.
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PMID:Quantitation of countercurrent exchange during passive absorption from the dog small intestine: evidence for marked species differences in the efficiency of exchange. 83 78

The intestinal absorption of sodium taurocholate was studied in the near-term fetal and neonatal dog. Absorption rates were measured in vivo in isolated loops of fetal jejunum and ileum. Absorption was also measured in vitro in everted sacs and rings of fetal and neonatal jejunum and ileum. The maximal rates of taurocholate absorption observed after instillation of 1 micronmol taurocholate into closed segments of fetal jejunum and ileum with intact blood supply were not significantly different (P less than 0.2), and equalled 0.282+/-0.026 (mean+/-SEM) and 0.347+/-0.051 micronmol/h per 10-cm segment length jejunum and ileum, respectively. Similarly, the rates of absorption from open segments of jejunum and ileum perfused with 0.4 and 1.0 mM taurocholate were nearly identical (0.232+/-0.040 and 0.255+/-0.039, respectively at 0.4 mM, and 0.470+/-0.065 and 0.431+/-0.013, respectively at 1.0 mm) (P greater than 0.2). At perfusate concentrations of 4.0 mM, moreoever, jejunal absorption exceeded ileal absorption (1.490+/-0.140 and 0.922+/-0.200, respectively (P less than 0.05). As expected, concentration of taurocholate by the mucosa was readily demonstrated in adult ileal, but not in adult jejunal everted rings. In contrast, there were no significant differences in mucosal uptake of taurocholate by fetal jejunal and ileal rings. Fetal ileal mucosal concentrations were not significantly above those in the incubation medium after 1-h exposure of the mucosa to 0.003, 0.03, and 0.3 mM taurocholate. Uptake was proportional to incubation medium concentration over the full range of values. This was also true of tissues from 1-wk-old neonates. However, by 2 wk of age, ileal mucosal concentration of taurocholate was evident and adult levels were attained by 5 wk of age. It is concluded that taurocholate is absorbed by the fetal gut and that ileal absorption is no more efficient than jejunal absorption. Although active glucose transport was demonstrable in both jejunum and ileum, it was not possible to demonstrate an ileal mechanism for active transport of taurocholate in the fetus. Active ileal transport was not demonstrable in the newborn until at least 2 wk after birth.
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PMID:Fetal bile salt metabolism. The intestinal absorption of bile salt. 86 98

Peripherally harvested lymphocytes have been labelled with 51Cr, reinjected into human subjects and their distribution then studied. Evidence is presented which suggests faecal loss of 51Cr represents loss of T lymphocytes and that there is normally a pathway of lymphocyte removal into the gut of probable importance in lymphocyte migration streams. In 9 normal subjects, without structural intestinal disease, faecal loss of lymphocytes over 5 days was 0.20% (SEM +/- 0.06) whereas in 5 patients with untreated coeliac disease faecal loss was 1.13 +/- 0.34%, in 7 with Crohn's disease it was 1.01 +/- 0.21% and in 5 with intestinal lymphangiectasia loss was 0.61 +/- 0.10%. In 1 patient with acute tropical sprue, enteric loss was 0.97%. By contrast, faecal loss was normal in 3 coeliac patients in remission on a gluten-free diet. Measurements were also made using an external counter. In contrast to the normals, where count rates steadily diminished, an increasing activity was recorded over the umbilicus over 7 days after dose administration in all the disease categories studied with the exception of the treated coeliacs. The finding of an increased enteric loss of lymphocytes may explain many of the immunological abnormalities in the conditions studied.
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PMID:The distribution and enteric loss of 51Cr-labelled lymphocytes in normal subjects and in patients with coeliac disease and other disorders of the small intestine. 95 24

Gut-associated lymphoid cells are modulated by several gut hormones. We postulated that lymphokine-associated-killer (LAK) cell cytotoxicity of lymphocytes isolated from the gut mucosa may be increased by substance P (SP). Intestinal lamina propria mononuclear cells (LPMC) and colonic cancer cells were isolated from operative specimens by successive mechanical and enzymatic dissociation methods. Effector LAK cells were induced by culturing LPMC with recombinant interleukin-2 at a concentration of 250 U/ml. Substance P (10(-5) M) was added to the culture medium. Targets consisted of fresh colon cancer cells, HT-29 (cultured human colon cancer cell line), and control cell lines. After 4 days of incubation, cytotoxicity was measured using a 4-h 51Cr release assay. LAK cells alone showed moderate cytotoxicity against HT-29 and none against fresh colon cancer cells. LAK cells generated in the presence of substance P showed moderate cytotoxicity against HT-29 and strong cytotoxicity against fresh colorectal cancer cells. The percentage of cytotoxicity +/- SEM at various effector to target ratios was [(*) denotes P < 0.05 compared with above]: [table: see text] We conclude that substance P significantly increases LAK cell cytotoxicity against fresh colon cancer cells, but not against cultured cells.
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PMID:Substance P increases in vitro lymphokine-activated-killer (LAK) cell cytotoxicity against fresh colorectal cancer cells. 127 74

Increased concentrations of fecal bile acids have been suggested to be associated with increased risk of colorectal cancer. Fecal bile acid profiles were determined in 12 healthy Finnish women who included in their normal diets for 2-week periods in turn three different types of bread, 200-300 g/day. The breads contained either low-fiber wheat, whole-meal wheat, or whole-grain rye. During consumption of rye bread, the total mean concentration of fecal free bile acids was 4.77 +/- 0.90 mumol/g of dry feces (mean +/- SEM), which was much lower than with the normal omnivorous diet (8.05 +/- 1.56 mumol/g) or during administration of the low-fiber wheat bread (8.83 +/- 1.56 mumol/g) or the whole-meal wheat bread (7.88 +/- 1.34 mumol/g) (P less than 0.05). This decrease was mainly caused by increased proportions of saponifiable bile acids (P less than 0.01). During intake of the whole-grain rye bread, 46% +/- 3% of the fecal bile acids were in their saponifiable forms; this percentage was 30% +/- 3% during the control period, 30% +/- 4% during the low-fiber wheat bread period, and 27% +/- 4% during the whole-meal wheat bread period. It is concluded that the type of bread significantly effects concentrations of cocarcinogenic and comutagenic free lithocholic and deoxycholic acids by changing modes of conjugation in the gut.
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PMID:Fecal bile acid metabolic pattern after administration of different types of bread. 132 33

The techniques commonly used to evaluate the transit of contents through the gut feature some limitations for being either inaccurate, invasive, inconvenient, or potentially dangerous for the subjects. Aim of this study was to establish a safe, noninvasive and accurate technique for the measurement of segmental oroanal transit time. We localized an orally ingested magnetic marker by means of a biomagnetic instrumentation that allows us to identify in a three-dimensional pattern the position of a biomagnetic source inside the body. The biomagnetic localizations were compared with the anatomical data obtained by magnetic resonance imaging investigations. The study was performed in 12 healthy subjects, and scans were taken every hour up to the arrival of the marker into the cecum; thereafter, scans were taken every 4 hr up to the elimination of the marker. In 99% of the isofield maps obtained from each field scan, the marker was localized within the bowel walls. The mean oroanal transit time was 56 +/- 5 hr, the mouth-to-cecum transit time was 13 +/- 1.7 hr, and the total colonic transit time was 43.5 +/- 5 hr (mean +/- SEM). Segmental colon transit did not show major differences among the regions considered, although most of the time was spent in the right colon. In fact, a good correlation was found between transit time through the right colon and oroanal and total colonic transit (r = 0.77, P < 0.02, r = 0.79, P < 0.02 respectively). In conclusion, this method might be a safe alternative to the techniques presently used in the clinical setting for the measurement of intestinal transit.
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PMID:Measurement of segmental transit through the gut in man. A novel approach by the biomagnetic method. 139


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