Unique microbial-derived volatile organic compounds in portal venous circulation in murine non-alcoholic fatty liver disease.

BACKGROUND AND AIMS: Non-alcoholic fatty liver disease is now the leading liver disease in North America. The progression of non-alcoholic fatty liver disease to the inflammatory condition, non-alcoholic steatohepatitis is complex and currently not well understood. Intestinal microbial dysbiosis has been implicated in the development of non-alcoholic fatty liver disease and progression of non-alcoholic steatohepatitis. Volatile organic compounds are byproducts of microbial metabolism in the gut that may enter portal circulation and have hepatotoxic effects contributing to the pathogenesis of non-alcoholic steatohepatitis. To test this hypothesis, we measured volatile organic compounds in cecal luminal contents and portal venous blood in a mouse model of non-alcoholic steatohepatitis. METHODS: Gas chromatography-mass spectrometry analysis was conducted on cecal content and portal vein blood for volatile organic compound detection from mice fed a methionine and choline deficient diet, which induces non-alcoholic steatohepatitis. The colonic microbiome was studied by 16S rRNA gene amplification using the Illumina MiSeq platform. RESULTS: Sixty-eight volatile organic compounds were detected in cecal luminal content, a subset of which was also present in portal venous blood. Importantly, differences in portal venous volatile organic compounds were associated with diet-induced steatohepatitis establishing a biochemical link between gut microbiota-derived volatile organic compounds and increased susceptibility to non-alcoholic steatohepatitis. CONCLUSION: Our model creates a novel tool to further study the role of gut-derived volatile organic compounds in the pathogenesis of non-alcoholic steatohepatitis.

Exploring the interplay of barrier function and leukocyte recruitment in intestinal inflammation by targeting fucosyltransferase VII and trefoil factor 3.

Intestinal mucosal integrity is dependent on epithelial function and a regulated immune response to injury. Fucosyltransferase VII (Fuc-TVII) is an essential enzyme required for the expression of the functional ligand for E- and P-selectin. Trefoil factor 3 (TFF3) is involved in both protecting the intestinal epithelium against injury as well as aiding in wound repair following injury. The aim of the present study was to assess the interplay between barrier function and leukocyte recruitment in intestinal inflammation. More specifically, we aimed to examine how targeted disruption of Fuc-TVII either in wild-type or TFF3(-/-) mice would alter their susceptibility to colonic injury. TFF3 and Fuc-TVII double-knockout mice (TFF3/Fuc-TVII(-/-) mice) were generated by mating TFF3(-/-) and Fuc-TVII(-/-) mice. Colitis was induced by administration of dextran sodium sulfate (DSS) (2.5% wt/vol) in the drinking water. Changes in baseline body weight, diarrhea, and fecal blood were assessed daily. Upon euthanasia, extents of colonic inflammation were assessed macroscopically, microscopically, and through quantification of myeloperoxidase (MPO) activity. Colonic lymphocyte subpopulations were assessed at 6 days after administration of DSS by flow cytometry and immunohistochemistry. No baseline intestinal inflammation was found in TFF3/Fuc-TVII(-/-), TFF3(-/-), Fuc-TVII(-/-), or wild-type mice. Loss of Fuc-TVII resulted in a reduction in disease severity whereas TFF3(-/-) mice were markedly more susceptible to DSS-induced colitis. Remarkably, the loss of Fuc-TVII in TFF3(-/-) mice markedly decreased the severity of DSS-induced colitis as evidenced by reduced weight loss, diarrhea, decreased colonic MPO levels and improved survival. Furthermore, the loss of TFF3 resulted in increased severity of spontaneous colitis in IL-2/beta-microglobulin-deficient mice. These studies highlight the importance of the interplay between factors involved in the innate immune response, mucosal barrier function, and genes involved in regulating leukocyte recruitment and other aspects of the immune response.

The risk of gastrointestinal malignancies in cystic fibrosis: case report of a patient with a near obstructing villous adenoma found on colon cancer screening and Barrett's esophagus.

The life expectancy for cystic fibrosis (CF) patients has increased dramatically over the last 30 years. Although the overall cancer risk for CF patients does not appear to be increased there is a marked increased risk of gastrointestinal malignancies especially in the post lung transplant population. CF patients that do develop gastrointestinal malignancies do so at an earlier age and there is often a lag in the diagnosis and management of these individuals. We present a 39 year old male CF patient that underwent a colonoscopy for colon cancer screening and a large, near obstructing, villous adenoma of his ileum was found. The polyp was removed successfully via endoscopy without incident and there was no evidence of malignancy. An upper endoscopy revealed a long segment of Barrett's esophagus with no evidence of dysplasia. We present this case as well as a detailed review of the literature on cancer risk in CF and a discussion of the mechanisms that may be involved. We also present the risk of GI malignancies in non-CF patients as a guide on how to assess and manage the risk of GI malignancies in this ever-changing patient population.

Endoscopic management of gastric varices: efficacy and outcomes of gluing with N-butyl-2-cyanoacrylate in a North American patient population.

BACKGROUND: Gastric variceal bleeding is associated with significant morbidity and mortality in patients with portal hypertension. Outside of North America, gastric variceal injection of N-butyl-2-cyanoacrylate has been shown to be safe and effective. The majority of studies on this mode of therapy are in Asian populations in which the etiology of portal hypertension differs from North America. AIM: To assess the safety and efficacy of gastric variceal glue injection in a North American population. METHODS: Consecutive patients that underwent glue injection of gastric varices in the Calgary Health Region from 2001 to 2006 were assessed. RESULTS: Thirty-four patients (19 men, 15 women) underwent a total of 47 separate gluing procedures. Of those presenting with active bleeding at endoscopy, immediate hemostasis was achieved in 93.8% of patients. Rebleeding within 48 h of gluing was observed after four procedures. Gastric varices were eradicated in 84.0% of cases. Complications included superior mesenteric vein thrombosis in one patient. Twenty-eight (82.4%) patients were alive at the end of follow-up. The treatment failure-related mortality rate was 2.1%. CONCLUSIONS: The present study is one of the few to assess the role of gastric variceal gluing in a North American population. Glue injection with cyanoacrylate is safe and effective in the treatment of bleeding gastric varices.

A paradoxical reduction in susceptibility to colonic injury upon targeted transgenic ablation of goblet cells.

Goblet cells are the major mucus-producing cells of the intestine and are presumed to play an important role in mucosal protection. However, their functional role has not been directly assessed in vivo. In initial studies, a 5' flanking sequence of the murine intestinal trefoil factor (ITF) gene was found to confer goblet cell-specific expression of a transgene. To assess the role of goblet cells in the intestine, we generated transgenic mice in which approximately 60% of goblet cells were ablated by the expression of an attenuated diphtheria toxin (DT) gene driven by the ITF promoter; other cell lineages were unaffected. We administered 2 exogenous agents, dextran sodium sulfate (DSS) and acetic acid, to assess the susceptibility of mITF/DT-A transgenic mice to colonic injury. After oral administration of DSS, 55% of control mice died, whereas DT transgenic mice retained their body weight and less than 5% died. Similarly, 30% of the wild-type mice died after mucosal administration of acetic acid, compared with 3.2% of the transgenic mice. Despite the reduction in goblet-cell number, the total amount of ITF was increased in the mITF/DT-A transgenic mice, indicating inducible compensatory mechanisms. These results suggest that goblet cells contribute to mucosal protection and repair predominantly through production of trefoil peptides.

Reovirus decreases azoxymethane-induced aberrant crypt foci and colon cancer in a rodent model.

Reovirus type 3 Dearing has demonstrated oncolytic efficacy in vitro and in vivo against a variety of cancer cell lines, tumor xenografts and syngeneic cancer models. In this study, we investigated the effectiveness of reovirus against aberrant crypt foci (ACF) and colon cancer induced by the carcinogen azoxymethane (AOM) in an immunocompetent rat model. Sprague-Dawley rats received 15 mg/kg AOM intraperitoneally once per week for 4 weeks and reovirus was administered rectally once a week for 5 weeks starting 20 weeks after the last dose of AOM. Two weeks after completion of reovirus therapy, animals were examined for tumor burden in the colon and other tissues. Reovirus-treated animals showed a decrease in total ACF numbers (P=0.014), in large ACFs (P=0.0069) and in tumor number (P=0.03) compared to vehicle-treated animals. Fewer obstructing tumors in the colon (P=0.07) and duodenum (P=0.03) and reduced hepatic metastases were also noted. In addition, a tumor cell line derived from hepatic metastases was found to be susceptible to reovirus in vitro. Our results show that repeated rectal reovirus administration had some efficacy in the treatment and prevention of AOM-induced ACFs, colon cancers and metastases.

Gastric pouch adenocarcinoma and tubular adenoma of the pylorus: a field effect of dysplasia following bariatric surgery.

There are reports of gastric carcinoma following bariatric surgery, but it is unclear if these procedures predispose to malignancy. We present a case of a 60-year-old man who, 15 years after vertical banded gastroplasty (VBG), had a massive upper GI bleed. Endoscopy revealed a large tumor of the gastric pouch. Histology confirmed an intestinal type of gastric adenocarcinoma arising in a background of H. pylori-negative gastritis with atrophy, foveolar hyperplasia and intestinal metaplasia. An incidental tubular adenoma at the pylorus was also identified. The pathogenesis of gastric pouch carcinoma is discussed. The present example of neoplastic change in both the pouch and pylorus may indicate that a field effect for dysplasia develops subsequent to VBG.

The effects of pregnancy on the pharmacokinetics of infliximab and adalimumab in inflammatory bowel disease.

BACKGROUND: Transplacental transfer of infliximab and adalimumab results in detectable drug levels in the cord blood and infant. AIM: To determine if pregnancy influenced the pharmacokinetics of anti-TNF agents in women with inflammatory bowel disease. METHODS: Twenty-five women from the University of Calgary inflammatory bowel disease(IBD) pregnancy clinic on maintenance infliximab or adalimumab were recruited prospectively with serum bio-banking performed each trimester. Infliximab trough and adalimumab steady-state levels were the outcomes of interest and were analysed using the ANSER infliximab and adalimumab assays. Multivariate linear mixed-effects models were constructed to assess infliximab and adalimumab drug levels during pregnancy adjusting for the clinical covariates of albumin, BMI and CRP. RESULTS: Fifteen women (eight Crohn's disease, seven ulcerative colitis) received infliximab and 10 women with 11 pregnancies were treated with adalimumab. Median age was 29.6 years (IQR: 27.6-31.2 years). Median disease duration was 9.2 years (IQR: 3.16-15.0 years). Median trough infliximab concentrations were 8.50 µg/mL (IQR: 7.23-10.07 µg/mL), 10.31 µg/mL (IQR: 7.66-15.63 µg/mL) and 21.02 µg/mL (IQR: 16.01-26.70 µg/mL) at trimesters 1, 2 and 3 respectively. Significant changes in albumin and BMI (P < 0.05) but not CRP (P > 0.05) were documented throughout pregnancy. After adjusting for albumin, BMI and CRP, infliximab trough levels increased during pregnancy, by 4.2 µg/mL per trimester (P = 0.02), while adalimumab drug levels remained stable (P > 0.05). CONCLUSIONS: Infliximab levels rise during pregnancy, whereas adalimumab levels remain stable after accounting for changes in albumin, BMI and CRP. Therapeutic drug monitoring in the second trimester may be useful in guiding dosing in the third trimester.

Gut hormones, and short bowel syndrome: the enigmatic role of glucagon-like peptide-2 in the regulation of intestinal adaptation.

Short bowel syndrome (SBS) refers to the malabsorption of nutrients, water, and essential vitamins as a result of disease or surgical removal of parts of the small intestine. The most common reasons for removing part of the small intestine are due to surgical intervention for the treatment of either Crohn's disease or necrotizing enterocolitis. Intestinal adaptation following resection may take weeks to months to be achieved, thus nutritional support requires a variety of therapeutic measures, which include parenteral nutrition. Improper nutrition management can leave the SBS patient malnourished and/or dehydrated, which can be life threatening. The development of therapeutic strategies that reduce both the complications and medical costs associated with SBS/long-term parenteral nutrition while enhancing the intestinal adaptive response would be valuable. Currently, therapeutic options available for the treatment of SBS are limited. There are many potential stimulators of intestinal adaptation including peptide hormones, growth factors, and neuronally-derived components. Glucagon-like peptide-2 (GLP-2) is one potential treatment for gastrointestinal disorders associated with insufficient mucosal function. A significant body of evidence demonstrates that GLP-2 is a trophic hormone that plays an important role in controlling intestinal adaptation. Recent data from clinical trials demonstrate that GLP-2 is safe, well-tolerated, and promotes intestinal growth in SBS patients. However, the mechanism of action and the localization of the glucagon-like peptide-2 receptor (GLP-2R) remains an enigma. This review summarizes the role of a number of mucosal-derived factors that might be involved with intestinal adaptation processes; however, this discussion primarily examines the physiology, mechanism of action, and utility of GLP-2 in the regulation of intestinal mucosal growth.

Hematopoietic cell transplantation for Crohn's disease; is it time?

AIM: To review all studies in the literature that have assessed Hematopoietic cell transplantation (HCT) and Crohn's disease (CD) with the ultimate aims of determining if this is a viable treatment option for those with CD. A secondary aim was to review the above literature and determine if the studies shed further light on the mechanisms involved in the pathogenesis of CD. METHODS: An extensive Medline search was performed on all articles from 1970 to 2005 using the keywords; bone marrow transplant, stem cell, hematopoietic cell, Crohn's disease and inflammatory bowel disease. RESULTS: We identified one case in which a patient developed CD following an allogeneic HCT from a sibling suffering with CD. Evidence for transfer of the genetic predisposition to develop CD was also identified with report of a patient that developed severe CD following an allogeneic HCT. Following HCT it was found that the donor (that had no signs or symptoms of CD) and the recipient had several haplotype mismatches in HLA class III genes in the IBD3 locus including a polymorphism of NOD2/CARD15 that has been associated with CD. Thirty three published cases of patients with CD who underwent either autologous or allogeneic HCT were identified. At the time of publication 29 of these 33 patients were considered to be in remission. The median follow-up time was seven years, and twenty months for allogeneic and autologous HCT respectively. For patients who underwent HCT primarily for treatment of their CD there have been no mortalities related to transplant complications. CONCLUSION: Overall these preliminary data suggest that both allogeneic and autologous HCT may be effective in inducing remission in refractory CD. This supports the hypothesis that the hematolymphatic cells play a key role in CD and that resetting of the immune system may be a critical approach in the management or cure of CD.

NLRP3 regulates a non-canonical platform for caspase-8 activation during epithelial cell apoptosis.

Nod-like receptor, pyrin containing 3 (NLRP3) is characterized primarily as a canonical caspase-1 activating inflammasome in macrophages. NLRP3 is also expressed in the epithelium of the kidney and gut; however, its function remains largely undefined. Primary mouse tubular epithelial cells (TEC) lacking Nlrp3 displayed reduced apoptosis downstream of the tumor necrosis factor (TNF) receptor and CD95. TECs were identified as type II apoptotic cells that activated caspase-8, tBid and mitochondrial apoptosis via caspase-9, responses that were reduced in Nlrp3-/- cells. The activation of caspase-8 during extrinsic apoptosis induced by TNFα/cycloheximide (TNFα/CHX) was dependent on adaptor protein apoptosis-associated speck-like protein containing a CARD (ASC) and completely independent of caspase-1 or caspase-11. TECs and primary human proximal tubular epithelial cells (HPTC) did not activate a canonical inflammasome, caspase-1, or IL-1ß secretion in response to TNFα/CHX or NLRP3-dependent triggers, such as ATP or nigericin. In cell fractionation studies and by confocal microscopy, NLRP3 colocalized with ASC and caspase-8 in speck-like complexes at the mitochondria during apoptosis. The formation of NLRP3/ASC/caspase-8 specks in response to TNFα/CHX was downstream of TNFR signaling and dependent on potassium efflux. Epithelial ASC specks were present in enteroids undergoing apoptosis and in the injured tubules of wild-type but not Nlrp3-/- or ASC-/- mice following ureteric unilateral obstruction in vivo. These data show that NLRP3 and ASC form a conserved non-canonical platform for caspase-8 activation, independent of the inflammasome that regulates apoptosis within epithelial cells.

Herpes simplex virus type II infection of ileum mesothelium: a case report and review of the literature.

Disseminated herpes simplex virus (HSV) infection usually manifests in the immunocompromised. However, anecdotal examples of visceral HSV disease and viremia have complicated type I diabetes. A case of a 53-year-old type I diabetic patient with bowel obstruction one week subsequent to bronchitis is reported. At laparotomy, a perforated segment of ileum was associated with an adhesive peritoneal band. HSV cytopathic atypia and HSV immunohistochemical staining were confined to fibrocytes and mesothelial cells without involvement of the epithelium. Dissemination of symptomatic HSV pneumonia was verified by histology, immunohistochemistry, in situ hybridization, polymerase chain reaction and direct fluorescence antibody. Intravenous acyclovir resolved symptoms. This is a novel documentation of HSV complicating ileal adhesive band disease. Furthermore, this case indicates that the HSV cytopathic effect is not unique to the epithelium. Disseminated infection can manifest in myofibrocytes and mesothelium, distinguishing it from standard epithelial atypia of localized HSV infection.

Growth factors in inflammatory bowel disease.

The pathogenesis of both ulcerative colitis and Crohn's disease is unknown but these forms of inflammatory bowel disease (IBD) may be associated with an inability of the intestinal mucosa to protect itself from luminal challenges and/or inappropriate repair following intestinal injury. Numerous cell populations regulate these broad processes through the expression of a complex array of peptides and other agents. Growth factors can be distinguished by their actions regulating cell proliferation. These factors also mediate processes such as extracellular matrix formation, cell migration and differentiation, immune regulation, and tissue remodeling. Several families of growth factors may play an important role in IBD including: epidermal growth factor family (EGF) [transforming growth factor alpha (TGF alpha), EGF itself, and others], the transforming growth factor beta (TGF beta) super family, insulin-like growth factors (IGF), fibroblast growth factors (FGF), hepatocyte growth factor (HGF), trefoil factors, platelet-derived growth factor (PDGF), vascular endothelial growth factor (VEGF) and others. Collectively these families may determine susceptibility of IBD mucosa to injury and facilitate tissue repair.

Alternatives to Sulfasalazine: A Meta-analysis of 5-ASA in the Treatment of Ulcerative Colitis.

SUMMARY: : The purpose of this study was to assess the efficacy and safety of the newer release formulations of 5-aminosalicylic acid (5-ASA) compared with placebo or sulfasalazine (SASP) for the treatment of active disease and the maintenance of remission in ulcerative colitis. A computer-assisted literature search for relevant studies (1981-1996) was performed using MEDLINE, BIOS, and Science Citation Index, followed by a manual search of reference lists from previously retrieved articles, review articles, symposia proceedings, and abstracts from major gastrointestinal conferences. Studies were accepted for analysis if they were randomized, double-blinded, and controlled clinical trials of parallel design, with treatment durations of a minimum of 4 weeks for the treatment of active disease (19 studies), and a minimum of 6 months for maintenance therapy (16 studies). Based on an intention-to-treat principle, the outcomes of interest in the treatment of active disease were the failure to induce global/clinical remission, global/clinical improvement, endoscopic remission, or endoscopic improvement. For maintenance therapy, the primary measured outcome was the failure to maintain clinical or endoscopic remission. In active disease, 5-ASA was superior to placebo with regard to all measured outcome variables. For the failure to induce global/clinical improvement or remission, the pooled odds ratio was 0.39 [95% confidence interval (CI), 0.29-0.52]. A dose-response trend for 5-ASA was also observed. When 5-ASA was compared with SASP in active disease, the pooled odds ratio was 0.87 (CI, 0.63-1.20) for the failure to induce global/clinical improvement or remission, and 0.66 (CI, 0.42-1.04) for the failure to induce endoscopic improvement. In maintenance therapy, the pooled odds ratio for the failure to maintain clinical or endoscopic remission (withdrawals and relapses) for 5-ASA versus placebo was 0.48 (CI, 0.35-0.65) and versus SASP, 1.29 (CI, 1.06-1.57) at 6 months and 1.15 (0.89-1.50) at 12 months. SASP was not as well tolerated as 5-ASA in active disease despite their relatively similar tolerabilities in maintenance therapy. The newer 5-ASA preparations were superior to placebo for both active disease and maintenance of remission. In a patient population selected for tolerance to SASP, there is insufficient evidence to confirm their benefit over SASP for either active or maintenance therapy.

Hapten-induced chronic colitis in the rat: alternatives to trinitrobenzene sulfonic acid.

Hapten-induced colitis is a widely used model for the study of the intestinal inflammation and for the testing of novel therapies. However, the hapten utilized in this model, trinitrobenzene sulfonic acid, is difficult to obtain in some countries. We therefore compared this hapten to two structurally related haptens to determine if they could be substituted for trinitrobenzene sulfonic acid in terms of inducing chronic colitis in the rat. Rats received one of the three haptens intracolonically, and the severity of colonic inflammation was assessed 3 and 14 days later. Dinitrobenzene sulfonic acid produced colonic inflammation and ulceration that was indistinguishable from that induced by trinitrobenzene sulfonic acid at both time points. On the other hand, dinitrochlorobenzene produced acute colitis (3 days postadministration), but by Day 14 this inflammation had subsided. Dinitrobenzene sulfonic acid and trinitrobenzene sulfonic acid produced comparable levels of granulocyte infiltration into the colon (as measured by tissue myeloperoxidase activity and histology) at both time points. These studies suggest that for studies of up to at least 2 weeks in duration, dinitrobenzene sulfonic acid and trinitrobenzene sulfonic acid produce comparable levels of colonic inflammation. Dinitrobenzene sulfonic acid therefore offers a useful and less expensive alternative to trinitrobenzene sulfonic acid.

Benzocaine-induced methemoglobinemia: a condition of which all endoscopists should be aware.

Methemoglobinemia is a rare complication that can occur with the use of benzocaine-containing compounds. Two cases of methemoglobinemia are reported, and the pathophysiology and treatment of methemoglobinemia are reviewed. Both patients received topical 20% benzocaine spray before endoscopy. Immediately following the procedure, there was a reduction in O2 saturation assessed by pulse oximetry that was refractory to O2 therapy. Dramatic peripheral and central cyanosis developed. O2 saturation measured by pulse oximetry ranged from 83% to 87% on O2 by nasal prongs and 100% O2 by a nonrebreathing mask. Both patients were mildly confused and one patient complained of a significant headache. The diagnosis of methemoglobinemia was considered and arterial blood gas sampling was performed. In both patients, the arterial blood had a chocolate brown colour. A methemoglobin level of 48% and 18% was noted in patient 1 and patient 2, respectively. Both patients were treated with methylene blue, resulting in a significant improvement with gradual normalization of their O2 saturation within 10 min to 30 min. The use of benzocaine spray may not markedly alter the patient's perception of endoscopy and thus, the routine use of these agents should be questioned. If such agents are used, the physician must be aware of this association to prevent a delay in the diagnosis and management of this rare, but potentially lethal, condition.

Synchronous collagenous sprue and enteropathy-type T cell lymphoma: variants of the same disease.

A 64-year-old man with treated hypothyroidism had 10 months of diarrhea, abdominal pain, anorexia and recent involuntary 13.6 kg weight loss. He presented to hospital with an acute abdomen that had a radiological correlate of free air under the diaphragm. He was diagnosed with a perforated mid-jejunum due to an ulcerated enteropathy-type T cell lymphoma (ETL), complicating collagenous sprue and cryptic celiac disease. Polymerase chain reaction verified monoclonal gamma- and beta-T cell receptor gene rearrangements in the neoplasm. He had a complete resolution of symptoms when treated with a gluten-free diet in the postoperative period. This is apparently the first report describing collagenous sprue and ETL as synchronous lesions. Because atypical CD8+ lymphocytes are in both the collagenous sprue epithelium and ETL, the implication is that collagenous sprue is a noninvasive component of the ETL.

Octreotide in intestinal lymphangiectasia: lack of a clinical response and failure to alter lymphatic function in a guinea pig model.

Intestinal lymphangiectasia, which can be classified as primary or secondary, is an unusual cause of protein-losing enteropathy. The main clinical features include edema, fat malabsorption, lymphopenia and hypoalbuminemia. Clinical management generally includes a low-fat diet and supplementation with medium chain triglycerides. A small number of recent reports advocate the use of octreotide in intestinal lymphangiectasia. It is unclear why octreotide was used in these studies; although octreotide can alter splanchnic blood flow and intestinal motility, its actions on lymphatic function has never been investigated. A case of a patient with intestinal lymphangiectasia who required a shunt procedure after failing medium chain triglycerides and octreotide therapy is presented. During the management of this case, all existing literature on intestinal lymphangiectasia and all the known actions of octreotide were reviewed. Because some of the case reports suggested that octreotide may improve the clinical course of intestinal lymphangiectasia by altering lymphatic function, a series of experiments were undertaken to assess this. In an established guinea pig model, the role of octreotide in lymphatic function was examined. In this model system, the mesenteric lymphatic vessels responded to 5-hydroxytryptamine with a decrease in constriction frequency, while histamine administration markedly increased lymphatic constriction frequency. Octreotide failed to produce any change in lymphatic function when a wide range of concentrations were applied to the mesenteric lymphatic vessel preparation. In conclusion, in this case, octreotide failed to induce a clinical response and laboratory studies showed that octreotide did not alter lymphatic function. Thus, the mechanisms by which octreotide induced clinical responses in the cases reported elsewhere in the literature remain unclear, but the present study suggests that it does not appear to act via increasing lymphatic pumping.

HIV-related non-Hodgkin's lymphoma in Calgary.

OBJECTIVE: To determine the incidence of human immunodeficiency virus (HIV) associated non-Hodgkin's lymphoma (NHL) in a cohort of patients from a distinct geographic region (southern Alberta). The type and location of NHL as well as how it affected the survival of these patients was examined. PATIENTS AND METHODS: The Southern Alberta HIV Clinic in Calgary serves all of southern Alberta, which has an estimated population of one million. The clinic has provided primary care for 1086 patients from January 1983 to August 1995. Data were obtained by reviewing the clinic's database and patients' charts. RESULTS: Over a 12-year period, 39 cases of NHL were diagnosed in a group of 1086 HIV-infected patients. Presentation of NHL was at an extranodal site in all but four cases, with the most common sites being the bowel and central nervous system. The mean CD4 count on presentation with NHL was 143.4±37.4×10(6)/L (range 1 to 1219×10(6)/L). Mean survival was 1.25±0.25 years with a range from 0 (diagnosed on autopsy) to 6.45 years. Patients with a CD4 count of less than 200×10(6)/L and/or diagnosed with an AIDS-defining illness before development of NHL had significantly reduced survival (0.85 years versus 2.48 years, P<0.02 and 0.57 years versus 2.09 years, P<0.001, respectively). Patients who presented with NHL involving either nodes alone or central nervous system had significantly decreased survival (0.28 years and 0.29 years, respectively, P<0.05). Patients with NHL involving the gastrointestinal tract had a longer mean survival than those with NHL elsewhere (P<0.05). All but seven cases received therapy for NHL including chemotherapy, radiotherapy, surgery or combined therapy. Fifteen patients (47% of treated) achieved a complete response that led to improved survival (P<0.01). Patients tolerated surgery, chemotherapy and radiotherapy well and no deaths were due to NHL therapy. CONCLUSIONS: These data suggest that development of NHL in HIV is associated with reduced survival, and that survival is predominantly determined by CD4 count and site of involvement at the time of diagnosis of NHL.

Attenuation of Clostridium difficile toxin-induced damage to epithelial barrier by ecto-5'-nucleotidase (CD73) and adenosine receptor signaling.

BACKGROUND: Clostridium difficile (Cdf) releases toxins (TcdA and TcdB) that damage the intestinal epithelial barrier. Ecto-5'-nucleotidase (CD73) is expressed on intestinal epithelial cells, and it is hypothesized to protect against toxin-induced epithelial damage through the cleavage of 5'-AMP to adenosine (Ado) and subsequent activation of adenosine receptors (AdoRs). Herein, we sought to assess the potential protective effects of CD73 and AdoR signaling on the injurious effects of Cdf toxins. METHODS: Barrier function was assessed with T84 colonocytes. Transepithelial electrical resistance (TEER), paracellular fluorescein isothiocyanate (FITC)-dextran flux, and tight junction protein (ZO-1) integrity were monitored. Intrarectal installation of Cdf toxin was used to assess epithelial damage in vivo. KEY RESULTS: TcdA/B caused reduced TEER and increased paracellular flux in vitro. Concurrent treatment with 5'-AMP attenuated these responses to Cdf toxin; an effect that was blocked with ZM241385 (AdoRA2 antagonist). APCP, a CD73 inhibitor, also suppressed the protective effects of 5'-AMP on paracellular flux. 5'-AMP reduced toxin-induced disruption of ZO-1, an effect that was abolished by APCP and ZM241385. Inhibition of CD73 with APCP during Cdf toxin exposure led to increased intestinal barrier permeability and epithelial damage in vivo. Intrarectal instillation of 5'-AMP had no effect on toxin-induced intestinal injury. CONCLUSIONS & INFERENCES: Our data suggest that CD73 has a protective role against TcdA/B-induced damage. 5'-AMP treatment attenuated the damaging effects of Cdf toxin in vitro, and inhibitors of CD73 (APCP) and AdoRs (ZM241385) revealed that the cleavage of 5'-AMP to Ado was necessary for the protective effects. Inhibition of CD73 in vivo increases colonic tissue damage and epithelial permeability during Cdf toxin exposure.