Publications (12)51.83 Total impact
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Article: Immunizatiion history of children with inflammatory bowel disease.
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ABSTRACT: Protection against vaccine-preventable diseases is important in children with inflammatory bowel disease (IBD) due to frequent immunosuppressive therapy use. The chronic relapsing nature and treatment regimen of IBD may necessitate modified timing of immunizations. To evaluate the completeness of immunizations in children with IBD. Immunization records of all children with IBD followed at the Alberta Children's Hospital (Calgary, Alberta) were reviewed. For children with incomplete immunization according to the province of Alberta schedule, the reasons for such were clarified. Demographic data and age at diagnosis were also collected. Immunization records were obtained from 145 (79%) children with IBD. Fifteen children had incomplete routine childhood immunizations, including two with no previous immunizations. The most common incomplete immunizations included hepatitis B (n=9), diphtheria, tetanus, acellular pertussis at 14 to 16 years of age (n=7), and diphtheria, tetanus, acellular pertussis, inactivated polio at four to six years of age (n=6). The reasons for incomplete immunization included use of immunosuppressive therapy at time of scheduled immunization; IBD-related symptoms at time of scheduled immunization; parental refusal; recent move from elsewhere with different immunization schedule; unawareness of routine immunization; and needle phobia. Although the majority of children with IBD had complete childhood immunizations, suboptimal immunizations were present in 10%. With increasing use of immunosuppressive therapy in IBD, physicians caring for children with IBD must periodically evaluate immunization status and ensure the completeness of childhood immunizations.Canadian journal of gastroenterology = Journal canadien de gastroenterologie 04/2013; 27(4):213-6. · 1.21 Impact Factor -
Article: Immunogenicity and safety of influenza vaccination in children with inflammatory bowel disease
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ABSTRACT: Background:Protection against vaccine-preventable diseases is important in inflammatory bowel disease (IBD) because of increased susceptibility and severity of infection with immunosuppressive therapy. However, immunosuppressive therapy may affect vaccine response. This study aimed to evaluate immunogenicity and safety of influenza vaccination in children with IBD.Methods:In this prospective cohort study, 60 children with IBD and 53 healthy controls had serum collected for preimmunization hemagglutination-inhibition antibody titers to the 2008 inactivated influenza vaccine components. Three to 5 weeks following vaccine [A/Brisbane/10/2007(H3N2), A/Brisbane/59/2007(H1N1), B/Florida/4/2006] administration, all participants had serum collected for postimmunization titers. A 4-fold or greater increase between pre- and postimmunization titers indicated an immunogenic response; a postimmunization titer ≥1:40 indicated serologic protection. Children with IBD were classified into immunosuppression status by therapy.Results:Seventy percent, 72%, and 53% of children with IBD mounted an immunogenic response to H3N2, H1N1, and influenza B components, respectively. Among children with IBD, serologic protection was achieved in 95%, 98%, and 85% to H3N2, H1N1, and influenza B components, respectively. For influenza B, children with IBD were less likely to mount an immunogenic response compared to controls (53% versus 81%, P = 0.0009), and immunosuppressed children with IBD were less likely to achieve serologic protection compared to nonimmunosuppressed children with IBD (79% versus 100%, P = 0.02). The majority (98%) tolerated the vaccine.Conclusions:Although children with IBD achieve appropriate immunogenicity to influenza A, immunogenicity to influenza B appears to be diminished, especially with immunosuppressive therapy. (Inflamm Bowel Dis 2011;)Inflammatory Bowel Diseases 12/2011; 18(1):25 - 33. · 4.86 Impact Factor -
Article: Postoperative complications following colectomy for ulcerative colitis in children.
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ABSTRACT: Colectomy rates for ulcerative colitis (UC) and data on postcolectomy complications in children are limited. Thus, we assessed colectomy rates, early postcolectomy complications, and clinical predictors in children with UC undergoing a colectomy. Children (18 years old or older) with UC who underwent colectomy from 1983 to 2009 were identified (n=30). All of the medical charts were reviewed. The diagnostic accuracy of International Classification of Diseases codes for UC and colectomy were validated. The primary outcome was postoperative complications defined as Clavien-Dindo classification grade II or higher. The yearly incidence of colectomies for pediatric UC was calculated and temporal trends were evaluated. The sensitivity and positive predictive value of UC and colectomy International Classification of Diseases codes were 96% and 100%, respectively. The median ages at UC diagnosis and colectomy were 10.9 and 12.1 years, respectively. All of the children had pancolitis and 63% underwent emergent colectomy. Postoperatively, 33% experienced at least 1 complication. Patients with emergent colectomy were more likely to have a postoperative complication compared with patients with elective colectomy (90% vs 50%; P=0.03). For emergent colectomy, postoperative complications were associated with a disease flare of ≥2 weeks before admission (60% vs 0%; P=0.03) and >2 weeks from admission to colectomy (78% vs 22%; P=0.04). The average annual rate of pediatric colectomy was 0.059/100,000 person-years and stable from 1983 to 2009 (P>0.05). Colectomy UC was uncommon and rates have remained stable. Postcolectomy complications were common, especially in patients undergoing emergent colectomy. Optimizing timing of colectomy may reduce postoperative complications.Journal of pediatric gastroenterology and nutrition 12/2011; 54(6):763-8. · 2.18 Impact Factor -
Article: Immunogenicity and safety of influenza vaccination in children with inflammatory bowel disease.
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ABSTRACT: Protection against vaccine-preventable diseases is important in inflammatory bowel disease (IBD) because of increased susceptibility and severity of infection with immunosuppressive therapy. However, immunosuppressive therapy may affect vaccine response. This study aimed to evaluate immunogenicity and safety of influenza vaccination in children with IBD. In this prospective cohort study, 60 children with IBD and 53 healthy controls had serum collected for preimmunization hemagglutination-inhibition antibody titers to the 2008 inactivated influenza vaccine components. Three to 5 weeks following vaccine [A/Brisbane/10/2007(H3N2), A/Brisbane/59/2007(H1N1), B/Florida/4/2006] administration, all participants had serum collected for postimmunization titers. A 4-fold or greater increase between pre- and postimmunization titers indicated an immunogenic response; a postimmunization titer ≥1:40 indicated serologic protection. Children with IBD were classified into immunosuppression status by therapy. Seventy percent, 72%, and 53% of children with IBD mounted an immunogenic response to H3N2, H1N1, and influenza B components, respectively. Among children with IBD, serologic protection was achieved in 95%, 98%, and 85% to H3N2, H1N1, and influenza B components, respectively. For influenza B, children with IBD were less likely to mount an immunogenic response compared to controls (53% versus 81%, P = 0.0009), and immunosuppressed children with IBD were less likely to achieve serologic protection compared to nonimmunosuppressed children with IBD (79% versus 100%, P = 0.02). The majority (98%) tolerated the vaccine. Although children with IBD achieve appropriate immunogenicity to influenza A, immunogenicity to influenza B appears to be diminished, especially with immunosuppressive therapy.Inflammatory Bowel Diseases 04/2011; 18(1):25-33. · 4.86 Impact Factor -
Article: Association of Mycobacterium avium subspecies paratuberculosis with Crohn Disease in pediatric patients.
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ABSTRACT: The aim of the present study was to determine the prevalence of Mycobacterium avium subsp paratuberculosis (MAP) DNA in intestinal biopsies from pediatric patients with granulomatous Crohn disease (CD) or ulcerative colitis (UC), and matched control subjects without inflammatory bowel disease (IBD). DNA was extracted from formalin-fixed paraffin-embedded colonic and ileal biopsies from patients with CD (n = 22) or UC (n = 20), and from controls without IBD (n = 21). IS900 nested polymerase chain reaction was performed in triplicate to determine the presence of MAP-specific DNA. In mucosal biopsies from terminal ileum, IS900 amplicons were detected in 1 of 19 (5.2%) control subjects, 1 of 20 (5%) patients with UC, and 7 of 20 (35%) patients with CD (P < 0.05 vs controls, odds ratio 9.6). In colonic biopsies, IS900 amplicons were detected in 0 of 19 control subjects, 1 of 19 (5.2%) patients with UC, and 5 of 19 (26.3%) patients with CD (P < 0.05 vs controls, odds ratio 14.8). In patients with CD, there was no correlation between disease activity and the presence of IS900. Our technique enabled sensitive and specific detection of MAP DNA in archival endoscopic biopsy specimens. Although MAP-specific DNA can be detected in about 5% of intestinal biopsies from children with UC or controls without IBD, its presence was significantly associated with pediatric granulomatous CD, being particularly prevalent in ileal tissue. This easily defined clinical subset of patients may be useful for additional studies to determine the role of MAP in CD.Journal of pediatric gastroenterology and nutrition 02/2011; 52(2):170-4. · 2.18 Impact Factor -
Article: A new genetic subgroup of chronic granulomatous disease with autosomal recessive mutations in p40 phox and selective defects in neutrophil NADPH oxidase activity.
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ABSTRACT: Chronic granulomatous disease (CGD), an immunodeficiency with recurrent pyogenic infections and granulomatous inflammation, results from loss of phagocyte superoxide production by recessive mutations in any 1 of 4 genes encoding subunits of the phagocyte NADPH oxidase. These include gp91(phox) and p22(phox), which form the membrane-integrated flavocytochrome b, and cytosolic subunits p47(phox) and p67(phox). A fifth subunit, p40(phox), plays an important role in phagocytosis-induced superoxide production via a phox homology (PX) domain that binds to phosphatidylinositol 3-phosphate (PtdIns(3)P). We report the first case of autosomal recessive mutations in NCF4, the gene encoding p40(phox), in a boy who presented with granulomatous colitis. His neutrophils showed a substantial defect in intracellular superoxide production during phagocytosis, whereas extracellular release of superoxide elicited by phorbol ester or formyl-methionyl-leucyl-phenylalanine (fMLF) was unaffected. Genetic analysis of NCF4 showed compound heterozygosity for a frameshift mutation with premature stop codon and a missense mutation predicting a R105Q substitution in the PX domain. Parents and a sibling were healthy heterozygous carriers. p40(phox)R105Q lacked binding to PtdIns(3)P and failed to reconstitute phagocytosis-induced oxidase activity in p40(phox)-deficient granulocytes, with premature loss of p40(phox)R105Q from phagosomes. Thus, p40(phox) binding to PtdIns(3)P is essential for phagocytosis-induced oxidant production in human neutrophils and its absence can be associated with disease.Blood 09/2009; 114(15):3309-15. · 9.90 Impact Factor -
Article: Age of diagnosis influences serologic responses in children with Crohn's disease: a possible clue to etiology?
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ABSTRACT: Crohn's disease (CD) is often associated with antibodies to microbial antigens. Differences in immune response may offer clues to the pathogenesis of the disease. The aim was to examine the influence of age at diagnosis on the serologic response in children with CD. Data were drawn from 3 North American multicenter pediatric inflammatory bowel disease (IBD) research consortia. At or shortly after diagnosis, pANCA, ASCA IgA, ASCA IgG, anti-ompC, and anti-CBir1 were assayed. The results were compared as a function of age at CD diagnosis (0-7 years versus 8-15 years). In all, 705 children (79 <8 years of age at diagnosis, 626 >or=8 years) were studied. Small bowel CD was less frequent in the younger group (48.7% versus 72.6%; P < 0.0001), while colonic involvement was comparable (91.0% versus 86.5%). ASCA IgA and IgG were seen in <20% of those 0-7 years old compared to nearly 40% of those 8-15 years old (P < 0.001), while anti-CBir1 was more frequent in the younger children (66% versus 54%, P < 0.05). Anti-CBir1 detected a significant number of children in both age groups who otherwise were serologically negative. Both age at diagnosis and site of CD involvement were independently associated with expression of ASCA and anti-CBir1. Compared to children 8-15 years of age at diagnosis, those 0-7 years are more likely to express anti-CBir1 but only half as likely to express ASCA. These age-associated differences in antimicrobial seropositivity suggest that there may be different, and as yet unrecognized, genetic, immunologic, and/or microbial factors leading to CD in the youngest children.Inflammatory Bowel Diseases 12/2008; 15(5):714-9. · 4.86 Impact Factor -
Article: Increased immune reactivity predicts aggressive complicating Crohn's disease in children.
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ABSTRACT: The ability to identify children with CD who are at highest risk for rapid progression from uncomplicated to complicated phenotypes would be invaluable in guiding initial therapy. The aims of this study were to determine whether immune responses and/or CARD15 variants are associated with complicated disease phenotypes and predict disease progression. Sera were collected from 796 pediatric CD cases and tested for anti-Cbir1 (flagellin), anti-outer membrane protein C, anti-Saccharomyces cerevisiae, and perinuclear antineutrophil cytoplasmic antibody by using enzyme-linked immunosorbent assay. Genotyping (Taqman MGB) was performed for 3 CARD15 variants (single nucleotide polymorphisms 8, 12, and 13). Associations between immune responses (antibody sum and quartile sum score, CARD15, and clinical phenotype were evaluated. Thirty-two percent of patients developed at least 1 disease complication within a median of 32 months, and 18% underwent surgery. The frequency of internal penetrating, stricturing, and surgery significantly increased (P trend < .0001 for all 3 outcomes) with increasing antibody sum and quartile sum score. Nine percent of seropositive groups had internal penetrating/stricturing versus 2.9% in the seronegative group (P = .01). Twelve percent of seropositive groups underwent surgery versus 2% in the seronegative group (P = .0001). The highest antibody sum group (3) and quartile sum score group (4) demonstrated the most rapid disease progression (P < .0001). Increased hazard ratio was observed for antibody sum group 3 (7.8; confidence interval, 2.2-28.7), P < .002 and quartile sum score group 4 (11.0; confidence interval, 1.5-83.0, P < .02). The rate of complicated CD increases in children as the number and magnitude of immune reactivity increase. Disease progression is significantly faster in children expressing immune reactivity.Clinical gastroenterology and hepatology: the official clinical practice journal of the American Gastroenterological Association 07/2008; 6(10):1105-11. · 5.64 Impact Factor -
Article: Biliary atresia: the Canadian experience.
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ABSTRACT: To determine the outcomes of Canadian children with biliary atresia. Health records of infants born in Canada between January 1, 1985 and December 31, 1995 (ERA I) and between January 1, 1996 and December 31, 2002 (ERA II) who were diagnosed with biliary atresia at a university center were reviewed. 349 patients were identified. Median patient age at time of the Kasai operation was 55 days. Median age at last follow-up was 70 months. The 4-year patient survival rate was 81% (ERA I = 74%; ERA II = 82%; P = not significant [NS]). Kaplan-Meier survival curves for patients undergoing the Kasai operation at age < or = 30, 31 to 90, and > 90 days showed 49%, 36%, and 23%, respectively, were alive with their native liver at 4 years (P < .0001). This difference continued through 10 years. The 2- and 4-year post-Kasai operation native liver survival rates were 47% and 35% for ERA I and 46% and 39% for ERA II (P = NS). A total of 210 patients (60%) underwent liver transplantation; the 4-year transplantation survival rate was 82% (ERA I = 83%, ERA II = 82%; P = NS). This is the largest outcome series of North American children with biliary atresia at a time when liver transplantation was available. Results in each era were similar. Late referral remains problematic; policies to ensure timely diagnosis are required. Nevertheless, outcomes in Canada are comparable to those reported elsewhere.The Journal of pediatrics 12/2007; 151(6):659-65, 665.e1. · 4.02 Impact Factor -
Article: IL-23 receptor (IL-23R) gene protects against pediatric Crohn's disease.
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ABSTRACT: The IL-23 receptor (IL-23R) has been found to be associated with small bowel Crohn's disease (CD) in a whole genome association study. Specifically, the rare allele of the R381Q single nucleotide polymorphism (SNP) conferred protection against CD. It is unknown whether IL-23R is associated with IBD in children. The aim was to examine the association of IL-23R with susceptibility to IBD in pediatric patients. DNA was collected from 609 subjects (151 CD and 52 ulcerative colitis [UC] trios). Trios were genotyped for the R381Q SNP of the IL-23R gene and SNP8, SNP12, SNP13, of the CARD15 gene using Taqman. The transmission disequilibrium test (TDT) was used for association to disease using GENEHUNTER 2.0. The rare allele of R381Q SNP was present in 2.7% of CD and 2.9% UC probands. The CARD15 frequency was 31.5% (CD) and 18% (UC). The IL-23R allele was negatively associated with inflammatory bowel disease (IBD): the R381Q SNP was undertransmitted in children with IBD (8 transmitted [T] versus 27 untransmitted [UT]; P = 0.001). This association was significant for all CD patients (6 T versus 19 UT; P = 0.009), especially for non-Jewish CD patients (2 T versus 17 UT; P = 0.0006). TDT showed a borderline association for UC (2 T versus 8 UT; P = 0.06). As expected, CARD15 was associated with CD in children by the TDT (58 T versus 22 UT P = 0.00006), but not with UC. The protective IL-23R R381Q variant was particularly associated with CD in non-Jewish children. Thus, the initial whole genome association study based on ileal CD in adults has been extended to the pediatric population and beyond small bowel CD.Inflammatory Bowel Diseases 06/2007; 13(5):511-5. · 4.86 Impact Factor -
Article: Serum immune responses predict rapid disease progression among children with Crohn's disease: immune responses predict disease progression.
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ABSTRACT: Crohn's disease (CD) is a heterogeneous disorder characterized by diverse clinical phenotypes. Childhood-onset CD has been described as a more aggressive phenotype. Genetic and immune factors may influence disease phenotype and clinical course. We examined the association of immune responses to microbial antigens with disease behavior and prospectively determined the influence of immune reactivity on disease progression in pediatric CD patients. Sera were collected from 196 pediatric CD cases and tested for immune responses: anti-I2, anti-outer membrane protein C (anti-OmpC), anti-CBir1 flagellin (anti-CBir1), and anti-Saccharomyces-cerevisiae (ASCA) using ELISA. Associations between immune responses and clinical phenotype were evaluated. Fifty-eight patients (28%) developed internal penetrating and/or stricturing (IP/S) disease after a median follow-up of 18 months. Both anti-OmpC (p < 0.0006) and anti-I2 (p < 0.003) were associated with IP/S disease. The frequency of IP/S disease increased with increasing number of immune responses (p trend = 0.002). The odds of developing IP/S disease were highest in patients positive for all four immune responses (OR (95% CI): 11 (1.5-80.4); p = 0.03). Pediatric CD patients positive for > or =1 immune response progressed to IP/S disease sooner after diagnosis as compared to those negative for all immune responses (p < 0.03). The presence and magnitude of immune responses to microbial antigens are significantly associated with more aggressive disease phenotypes among children with CD. This is the first study to prospectively demonstrate that the time to develop a disease complication in children is significantly faster in the presence of immune reactivity, thereby predicting disease progression to more aggressive disease phenotypes among pediatric CD patients.The American Journal of Gastroenterology 02/2006; 101(2):360-7. · 7.28 Impact Factor -
Article: How to overcome the numerical instability of the scheme of divided differences?
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ABSTRACT: The scheme of divided differences is widely used in many approximation and interpolation problems. Computing the Newton coefficients of the interpolating polynomial is the first step of the Bj\"{o}rck and Pereyra algorithm for solving Vandermonde systems of equations (Cf. \cite{bjorck: 70}). Very often this algorithm produces very accurate solution. The problem of determining the Newton coefficients is intimately related with the problem of evaluation the Lagrange interpolating polynomial, which can be realized by many algorithms. For these reasons we use the uniform approach and analyze also Aitken's algorithm of the evaluation of an interpolating polynomial. We propose new algorithms that are always numerically stable with respect to perturbation in the function values and more accurate than the Aitken's algorithm and the scheme of divided differences, even for complex data.08/2004;
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2011
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The University of Calgary
- Department of Paediatrics
Calgary, Alberta, Canada
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