Biomedical subjects

Ciarán P Kelly

Publications and source records attributed to Ciarán P Kelly.

13 recordsLinked to original sources

PubMed2007

Quantifying gastric Helicobacter pylori infection: a comparison of quantitative culture, urease breath testing, and histology.

Although there are several methods to detect Helicobacter pylori infection, there is no simple validated test to quantify the density of infection, which is believed to play a major role in the pathogenesis of H. pylori-associated gastritis and peptic ulceration. The aim of this study was to evaluate and compare noninvasive and invasive tests for assessing the level of H. pylori infection so as to facilitate the development and clinical testing of new antibiotic treatments. Healthy volunteers (n=323) were screened for H. pylori infection by serology and, if positive (n=86), invited to undergo (13)C urea breath testing (UBT) (n=55). An increase of >2.4 parts per thousand (13)CO(2) at 15 min compared to baseline was considered a positive test. Total cumulative urease activity (mumol) at 60 min was also calculated. UBT-positive subjects underwent endoscopy and nine biopsies were obtained from defined sites for quantitative culture and histological grading using the modified Sydney System. A total of 19 subjects were studied, 4 of whom underwent repeat testing. All subjects were positive for H. pylori by serology, UBT, culture, and histology. The increase in (13)CO(2) at 30 min correlated with the total cumulative urease activity at 60 min (r (2)=0.92, P< 0.0001). Bacterial counts (log cfu/biopsy; mean+/-SD) were 3.9+/-0.5, 3.9+/-0.4, and 3.9+/-0.6 at the lesser curve antrum, greater curve antrum, and corpus, respectively. There was no significant correlation between UBT results and bacterial counts at any biopsy site. Nor was there any significant correlation between the histology grading and either the UBT or the bacterial counts at any site. This study indicates that there is little correlation among the three methods used to measure bacterial burden in H. pylori infection. Thus, decrements in bacterial numbers during single-agent therapy cannot be measured reliably by UBT and therefore cannot be used to evaluate the potential efficacy of novel agents to treat gastric H. pylori infection.

Adult↗

PubMed2006

Saccharomyces boulardii inhibits ERK1/2 mitogen-activated protein kinase activation both in vitro and in vivo and protects against Clostridium difficile toxin A-induced enteritis.

Saccharomyces boulardii (Sb), a probiotic yeast, protects against intestinal injury and inflammation caused by a wide variety of enteric pathogens, including Clostridium difficile. Given the broad range of protective effects of Sb in multiple gastrointestinal disorders, we hypothesize that Sb modulates host signaling pathways involved in intestinal inflammatory responses. In this study, we found that Sb culture supernatant (SbS) inhibits interleukin-8 production induced by C. difficile toxin A or IL-1beta in human colonocyte NCM460 cells in a dose-dependent fashion. Furthermore, SbS inhibited IL-1beta and toxin A induced Erk1/2 and JNK/SAPK but not p38 activation in NCM460 cells. To test whether this inhibition also occurs in vivo, we used a previously established mouse ileal loop model. On its own, SbS had no significant effect on basal fluid secretion or intestinal histology. However, Erk1/2 activation was significantly inhibited by SbS in toxin A exposed mouse ileal mucosa. In control loops, toxin A increased fluid secretion (2.2-fold), histological score (3.3-fold), and levels of the chemokine KC (4.5-fold). SbS pretreatment completely normalized toxin A mediated fluid secretion (p < 0.01), and histopathologic changes (p < 0.01) and substantially inhibited toxin A-associated KC increases (p < 0.001). In summary, the probiotic yeast S. boulardii inhibits C. difficile toxin A-associated enteritis by blocking the activation of Erk1/2 MAP kinases. This study indicates a new mechanism whereby Sb protects against intestinal inflammation and supports the hypothesis that Sb modulates host inflammatory signaling pathways to exert its beneficial effects.

Animals↗

PubMed2006

Body-mass index and symptoms of gastroesophageal reflux in women.

BACKGROUND: Overweight and obese persons are at increased risk for gastroesophageal reflux disease. An association between body-mass index (BMI)--the weight in kilograms divided by the square of the height in meters - and symptoms of gastroesophageal reflux disease in persons of normal weight has not been demonstrated. METHODS: In 2000, we used a supplemental questionnaire to determine the frequency, severity, and duration of symptoms of gastroesophageal reflux disease among randomly selected participants in the Nurses' Health Study. After categorizing women according to BMI as measured in 1998, we used logistic-regression models to study the association between BMI and symptoms of gastroesophageal reflux disease. RESULTS: Of 10,545 women who completed the questionnaire (response rate, 86 percent), 2310 (22 percent) reported having symptoms at least once a week, and 3419 (55 percent of those who had any symptoms) described their symptoms as moderate in severity. We observed a dose-dependent relationship between increasing BMI and frequent reflux symptoms (multivariate P for trend <0.001). As compared with women who had a BMI of 20.0 to 22.4, the multivariate odds ratios for frequent symptoms were 0.67 (95 percent confidence interval, 0.48 to 0.93) for a BMI of less than 20.0, 1.38 (95 percent confidence interval, 1.13 to 1.67) for a BMI of 22.5 to 24.9, 2.20 (95 percent confidence interval, 1.81 to 2.66) for a BMI of 25.0 to 27.4, 2.43 (95 percent confidence interval, 1.96 to 3.01) for a BMI of 27.5 to 29.9, 2.92 (95 percent confidence interval, 2.35 to 3.62) for a BMI of 30.0 to 34.9, and 2.93 (95 percent confidence interval, 2.24 to 3.85) for a BMI of 35.0 or more. Even in women with a normal baseline BMI, an increase in BMI of more than 3.5, as compared with no weight changes, was associated with an increased risk of frequent symptoms of reflux (odds ratio, 2.80; 95 percent confidence interval, 1.63 to 4.82). CONCLUSIONS: BMI is associated with symptoms of gastroesophageal reflux disease in both normal-weight and overweight women. Even moderate weight gain among persons of normal weight may cause or exacerbate symptoms of reflux.

Adult↗

PubMed2006

Saccharomyces boulardii produces a soluble anti-inflammatory factor that inhibits NF-kappaB-mediated IL-8 gene expression.

Saccharomyces boulardii (Sb) is a non-pathogenic yeast that ameliorates intestinal injury and inflammation caused by a wide variety of enteric pathogens. We hypothesized that Sb may exert its probiotic effects by modulation of host cell signaling and pro-inflammatory gene expression. Human HT-29 colonocytes and THP-1 monocytes were stimulated with IL-1beta, TNFalpha or LPS in the presence or absence of Sb culture supernatant (SbS). IL-8 protein and mRNA levels were measured by ELISA and RT-PCR, respectively. The effect of SbS on IkappaB alpha degradation was studied by Western blotting and on NF-kappaB-DNA binding by EMSA. NF-kappaB-regulated gene expression was evaluated by transient transfection of THP-1 cells with a NF-kappaB-responsive luciferase reporter gene. SbS inhibited IL-8 protein production in IL-1beta or TNFalpha stimulated HT-29 cells (by 75% and 85%, respectively; P<0.001) and prevented IL-1beta-induced up-regulation of IL-8 mRNA. SbS also inhibited IL-8 production, prevented IkappaB alpha degradation, and reduced both NF-kappaB-DNA binding and NF-kappaB reporter gene up-regulation in IL-1beta or LPS-stimulated THP-1 cells. Purification and characterization studies indicate that the S. boulardii anti-inflammatory factor (SAIF) is small (<1 kDa), heat stable, and water soluble. The probiotic yeast Saccharomyces boulardii exerts an anti-inflammatory effect by producing a low molecular weight soluble factor that blocks NF-kappaB activation and NF-kappaB-mediated IL-8 gene expression in intestinal epithelial cells and monocytes. SAIF may mediate, at least in part, the beneficial effects of Saccharomyces boulardii in infectious and non-infectious human intestinal disease.

Cells, Cultured↗

PubMed2005

Topical antisense oligonucleotide therapy against LIX, an enterocyte-expressed CXC chemokine, reduces murine colitis.

Epithelial neutrophil-activating peptide-78 (ENA-78), a member of the CXC chemokine subfamily, is induced by inflammatory cytokines in human colonic enterocyte cell lines and increased in the colon of patients with inflammatory bowel disease (IBD). Lipopolysaccharide-induced CXC-chemokine (LIX) was recently identified as the murine homolog of ENA-78. Here we show that, similar to ENA-78, inflammatory cytokine stimulation of a murine colonic epithelial cell line, MODE-K, results in increased LIX expression. Consistent with the expression pattern of ENA-78 in IBD, LIX expression is significantly increased in mice with colitis induced by the ingestion of dextran sodium sulfate (DSS). Treating mice with antisense oligonucleotides to LIX via rectal enema delivery before DSS treatment results in colonic enterocyte uptake and a significant reduction in neutrophil infiltration and severity of colitis. These findings indicate that LIX plays an integral role in the pathogenesis of DSS-induced colitis. Similarly, enterocyte-derived CXC chemokines may play a key role in regulating neutrophil recruitment and intestinal injury in IBD. The intracolonic administration of ENA-78 antisense oligonucleotides may be effective in treating distal ulcerative colitis in humans.

Animals↗

PubMed2005

Clostridium difficile toxoid vaccine in recurrent C. difficile-associated diarrhea.

BACKGROUND & AIMS: Recurrent C difficile -associated diarrhea (CDAD) is associated with a lack of protective immunity to C difficile toxins. A parenteral C difficile vaccine containing toxoid A and toxoid B was reported previously to be safe and immunogenic in healthy volunteers. Our aim was to examine whether the vaccine is also well tolerated and immunogenic in patients with recurrent CDAD. METHODS: Subjects received 4, 50-microg intramuscular inoculations of the C difficile vaccine over an 8-week period. Serum antitoxin antibodies were measured by ELISA, and toxin neutralizing activity was evaluated using the tissue culture cytotoxin assay. RESULTS: Three patients with multiple episodes of recurrent CDAD were vaccinated. Two of the 3 showed an increase in serum IgG antitoxin A antibodies (3-fold and 4-fold increases, respectively) and in serum IgG antitoxin B antibodies (52-fold and 20-fold, respectively). Both also developed cytotoxin neutralizing activity against toxin A and toxin B. Prior to vaccination, the subjects had required nearly continuous treatment with oral vancomycin for 7, 9, and 22 months, respectively, to treat recurrent episodes of CDAD. After vaccination, all 3 subjects discontinued treatment with oral vancomycin without any further recurrence. CONCLUSIONS: A C difficile toxoid vaccine induced immune responses to toxins A and B in patients with CDAD and was associated with resolution of recurrent diarrhea. The results of this study support the feasibility of active vaccination against C difficile and its toxins in high-risk individuals but must be validated in larger, randomized, controlled trials.

Adult↗

PubMed2004

Human antibody response to surface layer proteins in Clostridium difficile infection.

Clostridium difficile is a major cause of infectious diarrhoea in hospitalised patients. Surface layer proteins (SLPs) are the most abundant surface localised proteins expressed by C. difficile. The aim of this study was to examine the humoral immune response to C. difficile SLPs and its potential role in protection from C. difficile associated diarrhoea (CDAD). Serum antibodies to SLPs from C. difficile were measured by ELISA in a cohort of 146 patients (55 patients with CDAD, 34 asymptomatic carriers, and 57 controls). No significant difference was detected in serum IgM, IgA or IgG antibody levels between cases, carriers or control groups at any of the time points tested. However, patients with recurrent episodes of C. difficile diarrhoea had significantly lower IgM-anti-SLP levels than patients with a single episode on days 1, 3, 6 and 9 (p = 0.05, p = 0.009, p = 0.02, p = 0.049). The adjusted odds ratio for recurrent diarrhoea associated with a low day 3 serum IgM anti-SLP antibody level was 24.5 (95% confidence interval; 1.6-376.3). Further studies which examine the specific anti-SLP antibody responses to the colonising strain are warranted to determine if immune responses to C. difficile SLPs play a role in protection from CDAD.

Antibodies, Bacterial↗

PubMed2004

Update on the immunologic basis of Helicobacter pylori gastritis.

PURPOSE OF REVIEW: Helicobacter pylori is a ubiquitous bacterial pathogen that has evolved to chronically infect the gastric mucosal surface, evade host immune clearance, and cause peptic ulcer disease or gastric neoplasia in a significant minority of infected individuals. Understanding the colonization, persistence, and virulence determinants of the bacterium as well as the innate and adaptive immune responses of the host are critically important if we are to develop novel treatment strategies for eradication of infection and prevention of H. pylori-induced gastroduodenal disease. RECENT FINDINGS: Substantial progress has been made in understanding the role of CagA in altering gastric epithelial cell signaling pathways. Intracellular CagA has been shown to activate the Ras/MEK/ERK mitogen activated protein kinase cascade and to associate with epithelial tight-junction scaffolding protein ZO-1. CagA was shown to regulate cellular responses and possibly contribute to gastritis by phosphorylation-dependent pathways. A phosphorylation-independent mechanism for CagA intracellular effects has also been proposed. The potential for CagA to disrupt the apical junctional barrier and for the outer membrane protein oipA to promote IL-8 secretion and gastric inflammation have also been explored. A number of different mechanisms by which H. pylori escapes and evades host immune attack to cause chronic indolent inflammation have been uncovered. Meanwhile, the examination and development of new adjuvants and vaccine delivery mechanisms to induce mucosal immune responses against key bacterial antigens has been a continuing focus of investigation in both animal and human studies. SUMMARY: H. pylori induces gastritis through production of a variety of antigens, virulence factors, and soluble mediators. The bacterium also dysregulates, disarms, and evades host immune responses to maintain chronic colonization of the gastric mucosa. Understanding the mechanisms of its growth and survival in the human stomach are essential for the development of an effective vaccine and other novel eradication strategies.

Journal Article↗

PubMed2003

Clostridium difficile vaccine and serum immunoglobulin G antibody response to toxin A.

There is a strong association between serum antibody responses to toxin A and protection against Clostridium difficile diarrhea. A parenteral C. difficile toxoid vaccine induced very-high-level responses to anti-toxin A immunoglobulin G (IgG) in the sera of healthy volunteers. After vaccination, the concentrations of anti-toxin A IgG in the sera of all 30 recipients exceeded the concentrations that were associated with protection in previous clinical studies. Furthermore, the median concentration of serum anti-toxin A IgG in the test group was 50-fold higher than the previous threshold. These findings support the feasibility of using a vaccine to protect high-risk individuals against C. difficile-associated diarrhea and colitis.

Adult↗

PubMed2002

Celiac sprue.

Explore the source record for details and available documents.

Adult↗

PubMed2002

Underlying disease severity as a major risk factor for nosocomial Clostridium difficile diarrhea.

OBJECTIVE: To determine the diagnostic accuracy of an index of underlying disease severity (Horn's index) in identifying patients with a high probability of having nosocomial Clostridium difficile diarrhea as a complication of antimicrobial therapy. DESIGN: A prospective cohort study of 252 adult patients admitted to the hospital and receiving antibiotics. Risk facctors for C. difficile diarrhea were first determined retrospectively in a different cohort of 300 hospitalized patients (primary cohort) and then prospectively in this cohort of 252 hospitalized patients receiving antibiotics (secondary cohort). At the time of hospital admission, disease was rated by clinicians as mild (1), moderate (2), severe (3), or extremely severe (4) using a modified Horn's index. Multivariable logistic regression analysis was used to determine the odds ratio (OR) for C. difficile diarrhea associated with increasing levels of disease severity. SETTING: An urban teaching hospital affiliated with a medical school in Boston, Massachusetts. RESULTS: The incidence of nosocomial C. difficile diarrhea was 8.7% in the primary cohort and 11% in the secondary cohort In the prospective cohort study (secondary cohort), the OR for C. difficile diarrhea associated with extremely severe disease was 17.6 (95% confidence interval, 5.8 to 53.5). The sensitivity, specificity, and positive and negative predictive values of a Horn's index score of 3 or more (severe to extremely severe disease) as a predictor of nosocomial C. difficile diarrhea were 79%, 73%, 27%, and 96%, respectively. CONCLUSIONS: These findings provide a means of early stratification of hospitalized patients receiving antibiotics according to their risk for nosocomial C. difficile diarrhea. Patients with severe to extremely severe disease at the time of admission may benefit from careful monitoring of antibiotic prescribing and early attention to infection control issues. In the future, these "high-risk" patients may benefit from prophylaxis studies of novel agents being developed to prevent C. difficile diarrhea.

Adolescent↗

PubMed2002

Celiac sprue.

Celiac sprue, celiac disease, or gluten-sensitive enteropathy, is a malabsorption disorder of the small intestine that occurs after ingestion of wheat gluten in genetically susceptible individuals. This disease is characterized by intestinal malabsorption associated with villous atrophy of the small intestinal mucosa, clinical and histological improvement after adherence to strict gluten free diet, and relapse when gluten is reintroduced. Celiac sprue has a high prevalence in Western Europe and North America where it is estimated to affect 1:120 to 1:300 individuals. The pathogenesis of celiac sprue is related to inappropriate intestinal T-cell activation in HLA-DQ2 positive individuals triggered by antigenic peptides from wheat gluten or prolamins from barley and rye. Although previously thought to be mainly a disease of childhood onset, the diagnosis is increasingly being made in adults. There are a wide variety of presentations, which range from asymptomatic forms to severe diarrhea, weight loss and nutritional deficiencies. Extraintestinal manifestations including anemia, osteopenia or neurological disorders and associated conditions such as diabetes or hypothyroidism are commonly present. The availability of highly sensitive and specific serologic markers has dramatically facilitated the diagnosis of celiac sprue. However, the demonstration of characteristic histological abnormalities in a biopsy specimen of the small intestine remains the mainstay of diagnosis. Treatment consists of life-long avoidance of dietary gluten to control symptoms and to prevent both immediate and long-term complications.

Adult↗

PubMed2001

Health care costs and mortality associated with nosocomial diarrhea due to Clostridium difficile.

A total of 271 patients were prospectively followed up to determine whether patients whose hospital stay is complicated by diarrhea due to Clostridium difficile experience differences in cost and length of stay and survival rates when compared with patients whose stay is not complicated by C. difficile-associated diarrhea. Forty patients (15%) developed nosocomial C. difficile-associated diarrhea. These patients incurred adjusted hospital costs of $3669--that is, 54% (95% confidence interval [CI], 17%-103%)--higher than patients whose course was not complicated by C. difficile-associated diarrhea. The extra length of stay attributable to C. difficile-associated diarrhea was 3.6 days (95% CI, 1.5-6.2). C. difficile-associated diarrhea was not associated with excess 3-month or 1-year mortality after adjustment for age, comorbidity, and disease severity. On the basis of the findings of this study, a conservative estimate of the cost of this disease in the United States exceeds $1.1 billion per year.

Adult↗