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Biomedical subjects

William F Stenson

Publications and source records attributed to William F Stenson.

At least 19 recordsLinked to original sources
PubMed2007

Myd88-dependent positioning of Ptgs2-expressing stromal cells maintains colonic epithelial proliferation during injury.

We identified cellular and molecular mechanisms within the stem cell niche that control the activity of colonic epithelial progenitors (ColEPs) during injury. Here, we show that while WT mice maintained ColEP proliferation in the rectum following injury with dextran sodium sulfate, similarly treated Myd88(-/-) (TLR signaling-deficient) and prostaglandin-endoperoxide synthase 2(-/-) (Ptgs2(-/-)) mice exhibited a profound inhibition of epithelial proliferation and cellular organization within rectal crypts. Exogenous addition of 16,16-dimethyl PGE(2) (dmPGE(2)) rescued the effects of this injury in both knockout mouse strains, indicating that Myd88 signaling is upstream of Ptgs2 and PGE(2). In WT and Myd88(-/-) mice, Ptgs2 was expressed in scattered mesenchymal cells. Surprisingly, Ptgs2 expression was not regulated by injury. Rather, in WT mice, the combination of injury and Myd88 signaling led to the repositioning of a subset of the Ptgs2-expressing stromal cells from the mesenchyme surrounding the middle and upper crypts to an area surrounding the crypt base adjacent to ColEPs. These findings demonstrate that Myd88 and prostaglandin signaling pathways interact to preserve epithelial proliferation during injury using what we believe to be a previously undescribed mechanism requiring proper cellular mobilization within the crypt niche.

Animals↗
PubMed2006

Rapid transient absorption and biliary secretion of enantiomeric cholesterol in hamsters.

To probe the pathway and specificity of cholesterol absorption, the synthetic enantiomer of cholesterol (ent-cholesterol) and cholesterol were labeled with deuterium, gavaged into hamsters, and measured by negative ion mass spectrometry. Initial uptake of both tracers into the intestinal mucosa at 30 min was similar but cholesterol was temporarily retained there, whereas mucosal ent-cholesterol declined rapidly with concomitantly increased enrichment in both the systemic circulation and the gut lumen. In a 3 day fecal recovery study, ent-cholesterol was quantitatively recovered in the stool, whereas cholesterol absorption was 53.2%. ent-Cholesterol given by intracardiac injection was selectively secreted into bile, and the ratio of ent-cholesterol to cholesterol tracers in the gut lumen increased down the length of the small bowel, with the largest value being found in stool. ent-Cholesterol is efficiently taken up by the intestinal mucosa and undergoes transient enterohepatic recirculation, but it is quantitatively eliminated over 3 days as a result of selective secretion into bile and selective enrichment within the lumen of the intestine. These findings suggest that cholesterol absorption is structurally specific and likely to be mediated by enantiospecific cellular proteins.

Administration, Oral↗
PubMed2006

Celecoxib versus naproxen and diclofenac in osteoarthritis patients: SUCCESS-I Study.

PURPOSE: To evaluate the efficacy and upper gastrointestinal (UGI) safety of celecoxib, compared with nonspecific nonsteroidal anti-inflammatory drugs (NSAIDs), among patients with osteoarthritis. METHODS: A total of 13274 osteoarthritis patients from 39 countries were randomly assigned to double-blind treatment with either celecoxib 100 mg twice daily (BID), celecoxib 200 mg BID, or nonselective NSAID therapy (diclofenac 50 mg BID or naproxen 500 mg BID) for 12 weeks. Standard validated measures were used to assess osteoarthritis efficacy. Serious UGI events were evaluated by 2 blinded, independent, gastrointestinal events committees. RESULTS: Results from all primary efficacy assessments showed that both dosages of celecoxib were as effective as NSAIDs in treating osteoarthritis. Significantly more ulcer complications occurred within the nonselective NSAID group (0.8/100 patient-years) compared with the celecoxib group (0.1/100 patient-years) (odds ratio = 7.02; 95% confidence interval [CI], 1.46 to 33.80; P =.008). There were fewer ulcer complications in the celecoxib group compared with the NSAID group, both in patients taking concomitant aspirin and those not taking aspirin, but the difference reached statistical significance only in the latter comparison. The number of cardiovascular thromboembolic events was low and not statistically different between the groups (eg, myocardial infarction rates: celecoxib 10 events [0.55/100 patient-years] vs NSAIDs 1 event [0.11/100 patient-years], (P =.11), but the study was not powered to detect such differences. CONCLUSIONS: In the treatment of osteoarthritis, celecoxib is as effective as the nonspecific NSAIDs naproxen and diclofenac, but has significantly fewer serious upper gastrointestinal events.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed2006

Safety of celecoxib in patients with ulcerative colitis in remission: a randomized, placebo-controlled, pilot study.

BACKGROUND & AIMS: The safety of selective cyclooxygenase-2 inhibitors in patients with ulcerative colitis in remission is unknown. METHODS: We performed a placebo-controlled pilot trial to evaluate the safety of celecoxib in patients with ulcerative colitis in remission who had a present or past history of nonspecific arthritis, arthralgia, or other condition amenable to nonsteroidal anti-inflammatory drug therapy. A total of 222 patients with ulcerative colitis in remission were randomized to receive oral celecoxib 200 mg or placebo twice daily for 14 days. Remission was defined as a total Mayo Clinic score of 2 points or less and an endoscopic score of 1 point or less. Disease exacerbation was defined as a total Mayo Clinic score of 5 points or more and an increase in the endoscopic score of 1 point or more. The primary analysis was disease exacerbation through day 14 among patients who underwent randomization, had at least 1 dose of study drug, and had both endoscopy and Mayo Clinic disease activity index scores at the baseline and final assessments. RESULTS: Three percent of patients in the celecoxib group experienced disease exacerbation through day 14, as compared with 4% in the placebo group (P = .719). Eleven percent of patients in each group experienced a bowel-related adverse event (P > .20). CONCLUSIONS: Therapy with celecoxib for up to 14 days did not have a greater relapse rate than placebo in patients with ulcerative colitis in remission who had a present or past history of nonspecific arthritis, arthralgia, or other condition amenable to nonsteroidal anti-inflammatory drug therapy.

Adolescent↗
PubMed2006

Reactive hemophagocytic syndrome complicating the treatment of inflammatory bowel disease.

BACKGROUND AND AIMS: Reactive hemophagocytic syndrome (RHS) is a rare disease in which inappropriately activated macrophages consume bone marrow-derived cells. Most cases are associated with infection in the setting of immunodeficiency. The widespread use of immunosuppressive therapy in the treatment of inflammatory bowel disease (IBD) places patients with Crohn's disease and ulcerative colitis at risk of this complication. No concerted effort has been made to alert gastroenterologists of this condition, and treatment recommendations are lacking. The aims of this study were to describe the clinical and laboratory features of RHS associated with IBD and to review diagnostic criteria, treatment options, and pathogenesis. MATERIALS AND METHODS: Clinical and laboratory data were pooled from the clinical practice of the investigators and from published cases. Descriptive statistics were performed. RESULTS AND CONCLUSIONS: Seven cases of RHS complicating the treatment of IBD were identified. All patients were on immunosuppressive therapy, with nearly half taking >1 agent. All patients presented with fever, leukopenia, anemia, and hyperferritinemia. Infection by a member of the herpesvirus family or an intracellular pathogen precipitated RHS in 6 of 7 patients. The mortality rate was 29%. The diagnosis of RHS should be considered in patients with IBD taking immunosuppressive therapy who present with fever and cytopenia. Evaluation should begin with a serum ferritin. In patients with a serum ferritin > or =10,000 ng/mL, a bone marrow biopsy should be performed to confirm hemophagocytosis. If the initial evaluation is negative, then clinical suspicion should be maintained until the episode resolves.

Adult↗
PubMed2005

Increased prevalence of celiac disease and need for routine screening among patients with osteoporosis.

BACKGROUND: There is an increased prevalence of osteoporosis among patients with celiac disease. However, the relative prevalence of celiac disease among osteoporotic and nonosteoporotic populations is not known, and the benefit of screening the osteoporotic population for celiac disease remains controversial. METHODS: We evaluated 840 individuals, 266 with and 574 without osteoporosis, from the Washington University Bone Clinic by serologic screening for celiac disease. Individuals with positive serologic test results for antitissue transglutaminase or antiendomysial antibody were offered endoscopic intestinal biopsy to confirm the diagnosis of celiac disease. Individuals with biopsy-proven celiac disease were treated with a gluten-free diet and followed up for improvement in bone mineral density. RESULTS: Twelve (4.5%) of 266 patients with osteoporosis and 6 (1.0%) of 574 patients without osteoporosis tested positive by serologic screening for celiac disease. All but 2 serologically positive individuals underwent in-testinalbiopsy. Nine osteoporotic patients and 1 nonosteoporotic patient had positive biopsy results. The prevalence of biopsy-proven celiac disease was 3.4% among the osteoporotic population and 0.2% among the nonosteoporotic population. All biopsy-positive individuals tested positive by antitissue transglutaminase and antiendomysial antibody. The antitissue transglutaminase levels correlated with the severity of osteoporosis as measured by T score, demonstrating that the more severe the celiac disease the more severe the resulting osteoporosis. Treatment of the patients with celiac disease with a gluten-free diet resulted in marked improvement in T scores. CONCLUSIONS: The prevalence of celiac disease among osteoporotic individuals (3.4%) is much higher than that among nonosteoporotic individuals (0.2%). The prevalence of celiac disease in osteoporosis is high enough to justify a recommendation for serologic screening of all patients with osteoporosis for celiac disease.

Absorptiometry, Photon↗
PubMed2005

Fish oil fix.

Explore the source record for details and available documents.

Animals↗
PubMed2005

Differential role of tumor necrosis factor receptors in TNBS colitis.

BACKGROUND: Tumor necrosis factor alpha (TNFalpha) plays a central role in the pathology of T helper 1-mediated colitis such as Crohn's disease; however, the role of its 2 receptors in mediating pathology has not been fully explored. METHODS: Trinitrobenzene sulfonic acid colitis was used to induce colitis in mice lacking each of the TNF receptors (TNFRs) and in wild-type mice. TNFR1-/- mice lost more weight, became hypothermic, and had increased mortality compared with wild-type C57Bl/6 mice. TNFR2-/- mice, however, lost less weight, had normal temperatures, and had improved survival. RESULTS: Despite the improved clinical outcomes in TNFR2-/- mice, TNFalpha levels were increased in these mice. CONCLUSIONS: TNFalpha signaling through TNFR1 is protective in the trinitrobenzene sulfonic acid mouse model of inflammatory bowel disease.

Animals↗
PubMed2005

Opposing effects of tumor necrosis factor receptor 1 and 2 in sepsis due to cecal ligation and puncture.

Tumor necrosis factor (TNF)-alpha, a cardinal molecule in the cascade of sepsis-induced host injury, binds to two distinct receptors: tumor necrosis factor receptor (TNFR) 1 and TNFR2. We used the cecal ligation and puncture model of polymicrobial sepsis to elucidate the role of these receptors in sepsis pathogenesis. Mice lacking TNFR1 had prolonged survival with less hypothermia, whereas mice lacking TNFR2-/- had shortened survival and more profound hypothermia than wild-type mice. TNFR1-/- and TNFR2-/- mice had increased serum concentrations of interleukin (IL) 1beta and total TNF-alpha (free plus receptor bound) compared with wild-type mice, but there were no differences in IL6 or IL10 concentrations. Furthermore, free TNF-alpha was markedly elevated in the serum and peritoneal fluid of mice lacking TNFR2, supporting a role for this receptor in regulating the concentration of TNF-alpha. Lastly, apoptosis of ileal crypt epithelial cells was increased in mice lacking TNFR1, but there were no differences in lymphocyte apoptosis. These data suggest that in sepsis, TNFR1 mediates much of the TNF-alpha-induced pathology, whereas TNFR2 mediates protective effects.

Animals↗
PubMed2004

Dynamic antagonism between RNA-binding protein CUGBP2 and cyclooxygenase-2-mediated prostaglandin E2 in radiation damage.

Damage to intestinal epithelium limits the use of ionizing radiation (IR) in cancer therapy. Prostaglandins (PGs), generated through the action of cyclooxygenase-1 (COX-1) and COX-2 protect the intestinal stem cells from IR. In previous studies, we demonstrated that the RNA-binding protein CUGBP2 regulates the stability and translation of COX-2 mRNA by interacting with AU-rich sequences in 3' UTR. Here, we demonstrate a dynamic antagonistic relationship between CUGBP2 and COX-2. Both CUGBP2 and COX-2 are rapidly induced after IR in intestinal crypt epithelial cells in mice, but CUGBP2 protein expression is observed immediately and COX-2 protein expression is delayed. In contrast, administration of bacterial lipopolysaccharide induced COX-2 expression and PGE(2), resulting in the inhibition of CUGBP2 expression and radioprotection of the intestine. These effects were reversed by NS398, a COX-2-specific inhibitor, suggesting that lipopolysaccharide-mediated inhibition of CUGBP2 is a PG-dependent mechanism. Furthermore, CUGBP2 expression is higher in COX-1(-/-) and COX-2(-/-) mice than wild-type controls at basal conditions, which is further increased after IR.

Animals↗
PubMed2004

Apobec-1 protects intestine from radiation injury through posttranscriptional regulation of cyclooxygenase-2 expression.

BACKGROUND & AIMS: This study aimed to determine the role of the RNA binding protein apobec-1 in radioprotection of the intestine. METHODS: Apobec-1-deleted mice (APOBEC-1(-/-)) and wild-type controls were treated with 12 Gy of whole-body gamma-irradiation in a cesium irradiator. The number of surviving intestinal crypts was assessed 3.5 days after irradiation by using a clonogenic assay. Cyclooxygenase-2 messenger RNA and protein expression were determined by real-time polymerase chain reaction and Western blot, respectively. RNA stability was studied by examining the turnover of a chimeric transcript containing the cyclooxygenase-2 3' untranslated region cloned downstream of luciferase complementary DNA. Apobec-1 binding to the cyclooxygenase-2 3' untranslated region was studied by electrophoretic mobility shift and UV crosslinking assays. RESULTS: After gamma-irradiation, the survival of intestinal stem cells decreased significantly in APOBEC-1(-/-) mice. In wild-type mice treated with lipopolysaccharide before gamma-irradiation, intestinal stem cells were protected by marked increases in prostaglandin E 2 mediated by cyclooxygenase-2. No such effect was observed in the APOBEC-1(-/-) mice. The mechanism of this radioprotective effect involves the binding of apobec-1 to AU-rich sequences in the first 60 nucleotides of the 3' untranslated region of cyclooxygenase-2. Upon binding to the AU-rich sequences, apobec-1 stabilizes cyclooxygenase-2 messenger RNA. This stabilization process does not seem to be mediated by p38 mitogen-activated protein kinase pathways. CONCLUSIONS: Lipopolysaccharide increases intestinal stem cell survival through apobec-1-mediated regulation of cyclooxygenase-2 messenger RNA stability.

3' Untranslated Regions↗
PubMed2004

Prostaglandin E2 reduces radiation-induced epithelial apoptosis through a mechanism involving AKT activation and bax translocation.

Prostaglandin E2 (PGE2) synthesis modulates the response to radiation injury in the mouse intestinal epithelium through effects on crypt survival and apoptosis; however, the downstream signaling events have not been elucidated. WT mice receiving 16,16-dimethyl PGE2 (dmPGE2) had fewer apoptotic cells per crypt than untreated mice. Apoptosis in Bax(-/-) mice receiving 12 Gy was approximately 50% less than in WT mice, and the ability of dmPGE2 to attenuate apoptosis was lost in Bax(-/-) mice. Positional analysis revealed that apoptosis in the Bax(-/-) mice was diminished only in the bax-expressing cells of the lower crypts and that in WT mice, dmPGE2 decreased apoptosis only in the bax-expressing cells. The HCT-116 intestinal cell line and Bax(-/-) HCT-116 recapitulated the apoptotic response of the mouse small intestine with regard to irradiation and dmPGE2. Irradiation of HCT-116 cells resulted in phosphorylation of AKT that was enhanced by dmPGE2 through transactivation of the EGFR. Inhibition of AKT phosphorylation prevented the reduction of apoptosis by dmPGE2 following radiation. Transfection of HCT-116 cells with a constitutively active AKT reduced apoptosis in irradiated cells to the same extent as in nontransfected cells treated with dmPGE2. Treatment with dmPGE2 did not alter bax or bcl-x expression but suppressed bax translocation to the mitochondrial membrane. Our in vivo studies indicate that there are bax-dependent and bax-independent radiation-induced apoptosis in the intestine but that only the bax-dependent apoptosis is reduced by dmPGE2. The in vitro studies indicate that dmPGE2, most likely by signaling through the E prostaglandin receptor EP2, reduces radiation-induced apoptosis through transactivation of the EGFR and enhanced activation of AKT and that this results in reduced bax translocation to the mitochondria.

Animals↗
PubMed2003

TNFR1 mediates the radioprotective effects of lipopolysaccharide in the mouse intestine.

LPS is radioprotective in the mouse small intestine through a mechanism that includes the synthesis of cyclooxygenase-2 (COX-2) and PGE2. The goal of this study was to identify the intermediate steps in this process. We used wild-type (WT) C57BL/6 mice and knockouts for tumor necrosis factor receptors 1 and 2 (TNFR1-/-, TNFR2-/-) and recombination-activating gene 1-/- mice. Mice were given parenteral LPS and then subjected to 12 Gy total body gamma irradiation. The number of surviving intestinal crypts was assessed 3.5 days after irradiation using a clonogenic assay. Crypt cell apoptosis was assessed by histology. Parenteral administration of LPS induced COX-2 expression, PGE2 production, and radioprotection in WT and TNFR2-/- mice but not in TNFR1-/- mice. TNFR1-/- mice were radioprotected by administration of exogenous 16,16-dimethyl PGE2. Immunohistochemical studies localized TNFR1 and COX-2 expression to subeptihelial fibroblasts and villus epithelial cells. Radiation-induced apoptosis was reduced by pretreatment with LPS in WT and TNFR2-/- mice but not in TNFR1-/- mice. In the absence of LPS, crypt survival was elevated in TNFR1-/- when compared with WT mice. These findings demonstrate that TNFR1 function is required for LPS-induced radioprotection in C57BL/6 mice and define an essential role for TNFR1 function in the induction of COX-2 expression and PGE2 production in this process. The immunolocalization of TNFR1 and COX-2 expression to subepithelial fibroblasts following LPS administration suggests that this cell type plays an intermediate role in LPS-induced radioprotection in the intestine.

16,16-Dimethylprostaglandin E2↗
PubMed2003

Ionizing radiation up-regulates cyclooxygenase-2 in I407 cells through p38 mitogen-activated protein kinase.

The epithelial cell line I407 up-regulates cyclooxygenase-2 (COX-2) mRNA and protein expression following ionizing radiation exposure. Prostaglandin E2 (PGE2) production is concomitantly up-regulated. Irradiation of I407 cells also results in phosphorylation of the p38 mitogen-activated protein kinase and the p38 inhibitor SB203580 abrogates radiation-induced PGE2 synthesis. Wild-type p38alpha (p38alphaWT) and dominant-negative p38alpha (p38alphaDN) stable-transfectant clones of I407 cells were used to examine the role of the p38 mitogen-activated protein kinase pathway in the events controlling PGE2 synthesis after ionizing radiation. Treatment of p38alphaWT clones with gamma-radiation resulted in increased COX-2 protein levels and PGE2 synthesis similar to treated control-transfected cells. In contrast, the p38alphaDN clones failed to up-regulate COX-2 protein or increase PGE2 synthesis when irradiated. Exogenous arachidonate did not restore PGE2 synthesis by p38alphaDN cells. Radiation increased COX-2 mRNA stability and the p38 inhibitor SB203580 attenuated COX-2 mRNA stability in irradiated I407 cells. In contrast, irradiation had no effect on transcription from a COX-2 promoter/luciferase reporter plasmid in the presence or absence of SB203580. The data demonstrate a crucial role for p38alpha in COX-2 expression and PGE2 synthesis in an irradiated transformed epithelial cell line. Furthermore, they indicate that p38 activity is required at a step distal to arachidonate release, most probably COX-2 up-regulation, since exogenous arachidonate did not restore PGE2 synthesis.

Cells, Cultured↗
PubMed2003

Inhibition of indoleamine 2,3-dioxygenase augments trinitrobenzene sulfonic acid colitis in mice.

BACKGROUND & AIMS: Indoleamine 2,3-dioxygenase (IDO), an interferon gamma-induced intracellular enzyme, inhibits lymphocyte proliferation through tryptophan degradation. IDO is highly expressed in the mammalian intestine. We sought to determine whether IDO played a regulatory role in the T-cell helper 1 (Th1)-mediated trinitrobenzene sulfonic acid (TNBS) model of colitis. METHODS: Intrarectal TNBS was given to SJL/J mice along with either placebo or a specific IDO inhibitor. IDO protein and mRNA expression were assessed by Western blotting and real-time PCR. Colonic lamina propria mononuclear cells (LPMNCs) were isolated, fractionated, and cultured, in the presence and absence of IFN-gamma, to determine the cell type(s) expressing IDO. RESULTS: IDO is expressed by professional antigen-presenting cells in the lamina propria. Induction of TNBS colitis resulted in a significant increase in IDO mRNA (P = 0.005) and protein expression. IDO inhibition during TNBS colitis resulted in an 80% mortality compared with 10% for placebo-treated animals (P = 0.0089). IDO inhibition resulted in a more severe colitis both histologically and morphologically (P < 0.05) and significantly increased colonic proinflammatory cytokine expression compared with placebo-treated animals. CONCLUSIONS: IDO is expressed in the normal colon and is up-regulated in the setting of TNBS colitis. Inhibition of IDO during TNBS colitis resulted in increased mortality and an augmentation of the normal inflammatory response. These findings suggest that IDO plays an important role in the down-regulation of Th1 responses within the gastrointestinal tract.

Animals↗
PubMed2003

Fat-free foods supplemented with soy stanol-lecithin powder reduce cholesterol absorption and LDL cholesterol.

OBJECTIVE: The objective of this work was to show that fat-free, lecithin-formulated soy stanols lower cholesterol absorption and serum LDL cholesterol. DESIGN: Reduction in cholesterol absorption was measured in paired single-meal tests with or without formulated soy stanols (acute test), and changes in serum lipids were investigated in a 10-week, randomized, double-blind parallel trial in which formulated stanols or lecithin vehicle were given three times daily for the last 4 weeks (chronic test). SUBJECTS/SETTING: Forty-five normal or mildly hypercholesterolemic subjects were recruited for both studies. The 21 subjects (16 female, 5 male; mean age 32.5 years) in the absorption studies had the following mean lipid values: LDL cholesterol, 2.79 mmol/L and total cholesterol, 4.73 mmol/L. For the lipid reduction, 24 subjects (16 female, 8 male; mean age 50.6 years) were enrolled with mean LDL cholesterol and total cholesterol of 3.72 mmol/L and 5.66 mmol/L, respectively. INTERVENTION: Reduction in cholesterol absorption was measured using a lemonade beverage or egg whites that contained 625 mg stanols. Throughout the chronic study, subjects followed the American Heart Association Step I diet. During the 4-week treatment phase, subjects consumed daily a lemonade-flavored beverage containing either placebo or formulated soy stanols (1.9 g). MAIN OUTCOME MEASURES: Inhibition of cholesterol absorption was determined from the difference in plasma deuterated cholesterol enrichment after a test meal containing stanol-lecithin and one with lecithin vehicle only. In the chronic study, the primary endpoints were changes in LDL and total cholesterol. STATISTICAL ANALYSES PERFORMED: Paired or unpaired t tests were used to determine statistical significance. RESULTS: Stanol-lecithin reduced cholesterol absorption by 32.1% (P=.0045, n=10) and by 38.2% (P=.0022, n=11) when delivered in a lemonade-flavored beverage and in egg whites, respectively. Reduction in cholesterol absorption was strongly related to the initial level of absorbed cholesterol tracer in serum (r(s)=-0.739). Stanol-lecithin given in a beverage reduced total serum cholesterol by 10.1% (P=.0019, n=24) and LDL cholesterol by 14.3% (P=.0016, n=24). APPLICATIONS/CONCLUSIONS: Powdered soy stanol-lecithin lowers cholesterol absorption and LDL cholesterol when consumed in fat-free foods.

Adult↗