Endoscopic ultrasound of the canine abdomen

The aim of this study was to develop a standardized procedure for examination of the canine abdomen using endoscopic ultrasound and to describe the organs and structures that could be identified transgastrically. The abdomen of four healthy dogs and two cadavers were examined with endoscopic ultrasound. Five anatomic landmarks were used for standardized imaging of the cranial abdomen. These were the portal vein, splenic head and body, duodenum, left kidney, and aorta. High-resolution images of the following organs and structures could be made: distal esophagus, gastric wall from the cardia to the pylorus, liver, caudal vena cava, hepatic lymph nodes, liver hilus, and associated vessels, trifurcation of the celiac artery as well as the path of its branches and the left pancreatic limb and body. Structures that were more difficult to image were the distal duodenum and right pancreatic limb, the entire jejunum, ileum, and cecum as well as the tail of the spleen. Endoscopic ultrasound allowed excellent visualization of the gastric wall and regional structures without interference with gas artefacts. Centrally located organs such as the pancreas could be well examined transgastrically with endoscopic ultrasound without interference by overlying intestinal segments as is common with transabdominal ultrasound.

Effects of vasopressin on microcirculatory blood flow in the gastrointestinal tract in anesthetized pigs in septic shock

BACKGROUND: Vasopressin increases arterial pressure in septic shock even when alpha-adrenergic agonists fail. The authors studied the effects of vasopressin on microcirculatory blood flow in the entire gastrointestinal tract in anesthetized pigs during early septic shock. METHODS: Thirty-two pigs were intravenously anesthetized, mechanically ventilated, and randomly assigned to one of four groups (n=8 in each; full factorial design). Group S (sepsis) and group SV (sepsis-vasopressin) were made septic by fecal peritonitis. Group C and group V were nonseptic control groups. After 300 min, group V and group SV received intravenous infusion of 0.06 U.kg.h vasopressin. In all groups, cardiac index and superior mesenteric artery flow were measured. Microcirculatory blood flow was recorded with laser Doppler flowmetry in both mucosa and muscularis of the stomach, jejunum, and colon. RESULTS: While vasopressin significantly increased arterial pressure in group SV (P<0.05), superior mesenteric artery flow decreased by 51+/-16% (P<0.05). Systemic and mesenteric oxygen delivery and consumption decreased and oxygen extraction increased in the SV group. Effects on the microcirculation were very heterogeneous; flow decreased in the stomach mucosa (by 23+/-10%; P<0.05), in the stomach muscularis (by 48+/-16%; P<0.05), and in the jejunal mucosa (by 27+/-9%; P<0.05), whereas no significant changes were seen in the colon. CONCLUSION: Vasopressin decreased regional flow in the superior mesenteric artery and microcirculatory blood flow in the upper gastrointestinal tract. This reduction in flow and a concomitant increase in the jejunal mucosa-to-arterial carbon dioxide gap suggest compromised mucosal blood flow in the upper gastrointestinal tract in septic pigs receiving low-dose vasopressin.

Perioperative fluid management: comparison of high, medium and low fluid volume on tissue oxygen pressure in the small bowel and colon

BACKGROUND AND OBJECTIVE: Insufficient blood flow and oxygenation in the intestinal tract is associated with increased incidence of postoperative complications after bowel surgery. High fluid volume administration may prevent occult regional hypoperfusion and intestinal tissue hypoxia. We tested the hypothesis that high intraoperative fluid volume administration increases intestinal wall tissue oxygen pressure during laparotomy. METHODS: In all, 27 pigs were anaesthetized, ventilated and randomly assigned to one of the three treatment groups (n = 9 in each) receiving low (3 mL kg-1 h-1), medium (7 mL kg-1 h-1) or high (20 mL kg-1 h-1) fluid volume treatment with lactated Ringer's solution. All animals received 30% and 100% inspired oxygen in random order. Cardiac index was measured with thermodilution and tissue oxygen pressure with a micro-oximetry system in the jejunum and colon wall and subcutaneous tissue. RESULTS: Groups receiving low and medium fluid volume treatment had similar systemic haemodynamics. The high fluid volume group had significantly higher mean arterial pressure, cardiac index and subcutaneous tissue oxygenation. Tissue oxygen pressures in the jejunum and colon were comparable in all three groups. CONCLUSIONS: The three different fluid volume regimens tested did not affect tissue oxygen pressure in the jejunum and colon, suggesting efficient autoregulation of intestinal blood flow in healthy subjects undergoing uncomplicated abdominal surgery.

Upregulation of toll-like receptors in chronic enteropathies in dogs

Background: Inflammatory bowel disease (IBD) is thought to result from a dysregulated interaction between the host immune system and commensal microflora. Toll-like receptors (TLRs) recognize microbe-associated molecular patterns (MAMPs), but their role in enteropathies in dogs is unknown. Hypothesis: That there is a dysregulation of TLRs recognizing bacterial MAMPs in dogs with IBD. Animals: Sixteen healthy beagles and 12 dogs with steroid-treated (ST) and 23 dogs with food-responsive (FR) diarrhea. Methods: Prospective, observational study. mRNA expression of canine TLR2, 4, and 9 was evaluated by quantitative real-time RT-PCR in duodenal and colonic biopsies obtained before and after standard therapy. Samples from control dogs were taken at necropsy, with additional biopsies of stomach, jejunum, ileum, and mesenteric lymph node in 6 dogs. Results: There were significant differences (P small intestine >/= colon). Before therapy, ST expressed more mRNA than control dogs for all 3 receptors (P < .05). There were no significant differences between pretreatment and posttreatment values, even though 32/35 dogs improved clinically. No associations were found when comparing receptor mRNA expression with either histology or clinical activity scores. Conclusions and Clinical Importance: Bacteria-responsive TLR2, 4, and 9 are upregulated in duodenal and colonic mucosa in IBD. This might lead to increased inflammation through interaction with the commensal flora. The absence of significant changes after therapy despite clinical improvement might point toward the existence of a genetic predisposition to IBD as described in human IBD.

Role of selective alpha and beta adrenergic receptor mechanisms in rat jejunal longitudinal muscle contractility

Gut motility is modulated by adrenergic mechanisms. The aim of our study was to examine mechanisms of selective adrenergic receptors in rat jejunum. Spontaneous contractile activity of longitudinal muscle strips from rat jejunum was measured in 5-ml tissue chambers. Dose-responses (six doses, 10(-7) -3 x 10(-5)M) to norepinephrine (NE, nonspecific), phenylephrine (PH, alpha1), clonidine (C, alpha2), prenalterol (PR, beta1), ritodrine (RI, beta2), and ZD7714 (ZD, beta3) were evaluated with and without tetrodotoxin (TTX, nerve blocker). NE(3 x 10(-5)M) inhibited 74 +/- 5% (mean +/- SEM) of spontaneous activity. This was the maximum effect. The same dose of RI(beta2), PH(alpha1), or ZD(beta(3)) resulted in an inhibition of only 56 +/- 5, 43 +/- 4, 33 +/- 6, respectively. The calculated concentration to induce 50% inhibition (EC50) of ZD(beta3) was similar to NE, whereas higher concentrations of PH(alpha1) or RI(beta2) were required. C(alpha2) and PR(beta1) had no effect. TTX changed exclusively the EC50 of RI from 4.4 +/- 0.2 to 2.7 +/- 0.8% (p < 0.04). Contractility was inhibited by NE (nonspecific). PH(alpha1), RI(beta2), and ZD(beta3) mimic the effect of NE. TTX reduced the inhibition by RI. Our results suggest that muscular alpha1, beta2, and beta3 receptor mechanisms mediate adrenergic inhibition of contractility in rat jejunum. beta2 mechanisms seem to involve also neural pathways.

Tularemia in a common marmoset (Callithrix jacchus) diagnosed by 16S rRNA sequencing

We report a case of tularemia in a common marmoset (Callithrix jacchus) diagnosed by determination of the isolate's 16S ribosomal RNA (rRNA) gene sequence. Pathological examination of the animal revealed a multifocal acute necrotizing hepatitis, interstitial nephritis, splenitis, and lymphangitis of the mandibular, retropharyngeal, and cervical and mesenteric lymph nodes. Moreover, multiple foci of acute necrosis were found in the epithelium of the jejunum and the interstitium of the lung. Bacteriological investigations revealed a septicemia. The isolated infectious agent was uncommon, not routinely diagnosed in our laboratory and therefore difficult to identify by conventional tools in a reasonable time and effort. thus, we decided to perform a genetic analysis based on the 16S rRNA gene sequence. Thereby, an infection with Francisella tularensis, the causative agent of tularemia, was unambiguously diagnosed. This shows the great advantage 16S rRNA gene sequencing has as a general identification approach for unusual or rare isolates.

Clinical parameters, intestinal function, and IGF1 concentrations in colostrum-deprived and colostrum-fed newborn pony foals.

Colostrum (COL) contains cytokines and growth factors that may enhance intestinal development in neonates. The hypothesis of this study was that besides providing immunoglobulins, COL is important for intestinal function and meconium release in foals. Newborn foals were either fed COL (n = 5) or an equal amount of milk replacer (MR, n = 7) during the first 24 hours of life. To ensure passive immunity, all foals received 1 L plasma. Postnatal development, meconium release, intestinal motility, white blood cell count, insulin-like growth factor 1, and intestinal absorptive function (xylose absorption test) were evaluated. Clinical findings and meconium release were not affected by feeding of COL or MR. Ultrasonography revealed a slightly larger jejunum and stomach in group COL versus MR (P < 0.05). The percentage of polymorphonuclear leucocytes was higher in foals of group MR versus group COL (P < 0.05) and the percentage of lymphocytes was lower in MR compared with COL foals (P < 0.05). Plasma insulin-like growth factor 1 concentration increased during the first 14 days after birth in both groups. A xylose absorption test on Day 5 revealed similar increases in plasma xylose concentrations after oral intake. In conclusion, feeding of COL versus MR was without effect on meconium release and intestinal absorptive function. Differences between foals fed COL and MR with regard to intestinal function are apparently without clinical relevance. In foals that have not received maternal COL, there is no major risk of intestinal problems if they are fed MR and provided with immunoglobulins by transfusion of plasma.

Implementation of a virtual correlative light and transmission electron microscope

In the long run, the widespread use of slide scanners by pathologists requires an adaptation of teaching methods in histology and cytology in order to target these new possibilities of image processing and presentation via the internet. Accordingly, we were looking for a tool with the possibility to teach microscopic anatomy, histology, and cytology of tissue samples which would be able to combine image data from light and electron microscopes independently of microscope suppliers. With the example of a section through the villus of jejunum, we describe here how to process image data from light and electron microscopes in order to get one image-stack which allows a correlation of structures from the microscopic anatomic to the cytological level. With commercially available image-presentation software that we adapted to our needs, we present here a platform which allows for the presentation of this new but also of older material independently of microscope suppliers.

Early stages of experimental colon carcinogenesis inhibit mast cell-dependent mucosal immune function of the distal colon

Inhibition of local host immune reactions is one mechanism contributing to tumor progression. To determine if alterations in local immune functioning occur during colon carcinogenesis, a model mucosal immune response, type I hypersensitivity against the intestinal parasite Trichinella spiralis, was first characterized in normal mice and then examined during experimental colon carcinogenesis. Segments of sensitized colon mounted in Ussing chambers and challenged with T. spiralis-derived antigen resulted in a rise in short-circuit current ($\rm\Delta I\sb{sc}$) that was antigen-specific and inhibited by furosemide, implicating epithelial Cl$\sp-$ secretion as the ionic mechanism. The immune-regulated Cl$\sp-$ secretion by colonic epithelial cells required the presence of mast cells with surface IgE. Inhibition of potential anaphylactic mediators with various pharmacological agents in vitro implicated prostaglandins and leukotrienes as the principal mediators of the antigen-induced $\rm\Delta I\sb{sc}$, with 5-hydroxytryptamine also playing a role. Distal colon from immune mice fed an aspirin-containing diet (800 mg/kg powdered diet) ad libitum for 6 wk had a decreased response to antigen, confirming the major role of prostaglandins in generating the colonic I$\sb{\rm sc}$. To determine the effects of early stages of colon carcinogenesis on this mucosal immune response, mice were immunized with T. spiralis 1 day after or 8 wk prior to the first of 6 weekly injections of the procarcinogen 1,2-dimethylhydrazine (DMH). Responsiveness to antigenic challenge was suppressed in the distal colon 4-6 wk after the final injection of DMH. One injection of DMH was not sufficient to inhibit antigen responsiveness. The colonic epithelium remained sensitive to direct stimulation by exogenous Cl$\sp-$ secretagogues. Decreased antigen-induced $\rm\Delta I\sb{sc}$ in the distal colon was not due to systemic immune suppression by DMH, as the proximal colon and jejunum maintained responsiveness to antigen. Also, rejection of a secondary T. spiralis infection from the small intestine was not altered. Tumors eventually developed 25-30 wk after the final injection of DMH only in the distal portions of the colon. These results suggest that early stages of DMH-induced colon carcinogenesis manipulate the microenvironment such that mucosal immune function, as measured by immune-regulated Cl$\sp-$ secretion, is suppressed in the distal colon, but not in other regions of the gut. Future elucidation of the mechanisms by which this localized inhibition of immune-mediated ion transport occurs may provide possible clues to the microenvironmental changes necessary for tumor progression in the distal colon. ^

Gastrointestinal ultrasonography of normal Standardbred neonates and frequency of asymptomatic intussusceptions.

BACKGROUND Ultrasonographic appearance of the gastrointestinal (GI) tract of equine neonates has not been completely described. OBJECTIVES To describe (1) sonographic characteristics of the GI segments in normal nonsedated equine neonates, (2) intra- and interobserver variation in wall thickness, and (3) the sonographic appearance of asymptomatic intussusceptions, and (4) to compare age and sonographic findings of foals with and without asymptomatic intussusceptions. ANIMALS Eighteen healthy Standardbred foals ≤5 days of age. METHODS Prospective, cross-sectional blinded study. Gastrointestinal sonograms were performed stall-side. Intraobserver variability in wall thickness measurements was determined by calculating the coefficient of variation (CV). The Bland-Altman method was used to assess interobserver bias. Student's t-test and Fisher's exact test were used to test the association among presence of intussusceptions, age, and selected sonographic findings. RESULTS The reference ranges (95% predictive interval) for wall thickness were 1.6-3.6 mm for the stomach, 1.9-3.2 mm for the duodenum, 1.9-3.1 mm for the jejunum, 1.3-2.2 mm for the colon, and 0.8-2.7 mm for the cecum. Intraobserver wall thickness CV ranged from 8 to 21% for the 2 observers for 5 gastrointestinal segments. The interobserver bias for wall thickness measurements was not significant except for the stomach (0.14 mm, P < .05) and duodenum (0.29 mm, P < .05). Diagnostic images of mural blood flow could not be obtained. Asymptomatic intussusceptions were found in 10/18 neonates. Associations between sonographic variables or age and the presence of intussusceptions were not found. CONCLUSIONS AND CLINICAL IMPORTANCE Sonographic characteristics of the GI tract of normal Standardbred neonates can be useful in evaluating ill foals. Asymptomatic small intestinal intussusceptions occur in normal Standardbred neonates.

Ceco-cecal intussusception in a Simmental heifer

This report describes the clinical, laboratory and ultrasonographic findings in a Simmental heifer with a ceco-cecal intussusception. The general condition of the heifer was moderately reduced and it showed mild colic signs. Physical examination revealed a firm longish mass visible and palpable in the right flank. Findings upon rectal examination, fecal output und defecation were normal. Ultrasound examination of the mass revealed features typical for an intussusception. Based on the slow development of symptoms, normal fecal output and ultrasonography findings, a ceco-cecal intussusception was diagnosed. Right flank laparatomy was performed under general anaesthesia, and an end-to-side anastomosis between the jejunum and the spiral colon was made after resection of the intussuscepted intestines. Recovery was uneventful.

Bile Acids Induce Glucagon-Like Peptide 2 Secretion with Limited Effects on Intestinal Adaptation in Early Weaned Pigs

Early weaning is a stressful event characterized by a transient period of intestinal atrophy that may be mediated by reduced secretion of glucagon-like peptide (GLP) 2. We tested whether enterally fed bile acids or plant sterols could increase nutrient-dependent GLP-2 secretion and improve intestinal adaptation in weanling pigs. During the first 6 d after weaning, piglets were intragastrically infused once daily with either deionized water -control-, chenodeoxycholic acid -CDC; 60mg/kg body weight-, or b-sitoesterol -BSE; 100 mg/kg body weight-. Infusing CDC increased plasma GLP-2 -P menor que 0.05- but did not affect plasma GLP-1 and feed intake. The intestinal expression of Glp2r -glucagon-like peptide 2 receptor-, Asbt -sodium-dependent bile acid transporter-, Fxr -farnesoid X receptor-, and Tgr5 -guanosine protein?coupled bile acid receptor- genes were not affected by CDC treatment. The intragastric administration of CDC did not alter the weight and length of the intestine, yet increased the activation of caspase-3 in ileal villi -P menor que 0.02- and the expression of Il6 -interleukin 6; P menor que 0.002- in the jejunum. In contrast, infusing BSE did not affect any of the variables that were measured. Our results show that the enteral administration of the bile acid CDC potentiates the nutrient-induced secretion of endogenous GLP-2 in early-weaned pigs. Bile acid?enhanced release of GLP-2, however, did not result in improved intestinal growth, morphology, or inflammation during the postweaning degenerative phase.

Proteinase-activated receptor 2 (PAR2)-activating peptides: Identification of a receptor distinct from PAR2 that regulates intestinal transport

The effects of PAR2-activating PAR2-activating peptides, SLIGRL (SL)-NH2, and trans-cinnamoyl-LIGRLO (tc)-NH2 were compared with the action of trypsin, thrombin, and the PAR1 selective-activating peptide: Ala-parafluoroPhe-Arg-cyclohexylAla-Citrulline-Tyr (Cit)-NH2 for stimulating intestinal ion transport. These agonists were added to the serosa of stripped rat jejunum segments mounted in Ussing chambers, and short circuit current (Isc) was used to monitor active ion transport. The relative potencies of these agonists also were evaluated in two bioassays specific for the activation of rat PAR2: a cloned rat PAR2 cell calcium-signaling assay (PAR2-KNRK cells) and an aorta ring relaxation (AR) assay. In the Isc assay, all agonists, except thrombin, induced an Isc increase. The SL-NH2-induced Isc changes were blocked by indomethacin but not by tetrodotoxin. The relative potencies of the agonists in the Isc assay (trypsin≫SL-NH2>tc-NH2>Cit-NH2) were strikingly different from their relative potencies in the cloned PAR2-KNRK cell calcium assay (trypsin≫>tc-NH2 ≅ SL-NH2≫>Cit-NH2) and in the AR assay (trypsin≫>tc-NH2 ≅ SL-NH2). Furthermore, all agonists were maximally active in the PAR2-KNRK cell and AR assays at concentrations that were one (PAR2 -activating peptides) or two (trypsin) orders of magnitude lower than those required to activate intestinal transport. Based on the distinct potency profile for these agonists and the considerable differences in the concentration ranges required to induce an Isc effect in the intestinal assay compared with the PAR2-KNRK and AR assays, we conclude that a proteinase-activated receptor, pharmacologically distinct from PAR2 and PAR1, is present in rat jejunum and regulates intestinal transport via a prostanoid-mediated mechanism.

Luminal trypsin may regulate enterocytes through proteinase-activated receptor 2

Proteinase-activated receptor 2 (PAR-2) is a recently characterized G-protein coupled receptor that is cleaved and activated by pancreatic trypsin. Trypsin is usually considered a digestive enzyme in the intestinal lumen. We examined the hypothesis that trypsin, at concentrations normally present in the lumen of the small intestine, is also a signaling molecule that specifically regulates enterocytes by activating PAR-2. PAR-2 mRNA was highly expressed in the mucosa of the small intestine and in an enterocyte cell line. Immunoreactive PAR-2 was detected at the apical membrane of enterocytes, where it could be cleaved by luminal trypsin. Physiological concentrations of pancreatic trypsin and a peptide corresponding to the tethered ligand of PAR-2, which is exposed by trypsin cleavage, stimulated generation of inositol 1,4,5-trisphosphate, arachidonic acid release, and secretion of prostaglandin E2 and F1α from enterocytes and a transfected cell line. Application of trypsin to the apical membrane of enterocytes and to the mucosal surface of everted sacs of jejunum also stimulated prostaglandin E2 secretion. Thus, luminal trypsin activates PAR-2 at the apical membrane of enterocytes to stimulate secretion of eicosanoids, which regulate multiple cell types in a paracrine and autocrine manner. We conclude that trypsin is a signaling molecule that specifically regulates enterocytes by triggering PAR-2.

Eotaxin is required for the baseline level of tissue eosinophils

Eotaxin is an eosinophil-selective chemokine that is constitutively expressed in a variety of organs such as the intestine. Previous studies have demonstrated that the recruitment of eosinophils during inflammation is partially dependent on eotaxin, but the function of constitutive eotaxin during homeostasis has not been examined. To elucidate the biological role of this molecule, we now examine tissue levels of eosinophils in healthy states in wild-type and eotaxin-deficient mice. The lamina propria of the jejunum of wild-type mice is demonstrated to express eotaxin mRNA, but not mRNA for the related monocyte chemoattractant proteins. Wild-type mice contained readily detectable eosinophils in the lamina propria of the jejunum. In contrast, mice genetically deficient in eotaxin had a large selective reduction in the number of eosinophils residing in the jejunum. The reduction of tissue eosinophils was not limited to the jejunum, because a loss of thymic eosinophils was also observed in eotaxin-deficient mice. These studies demonstrate that eotaxin is a fundamental regulator of the physiological trafficking of eosinophils during healthy states. Because a variety of chemokines are constitutively expressed, their involvement in the baseline trafficking of leukocytes into nonhematopoietic tissue should now be considered.