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Biomedical subjects

D P Jewell

Publications and source records attributed to D P Jewell.

At least 19 recordsLinked to original sources
PubMed2006

Review article: interactions between genotype and response to therapy in inflammatory bowel diseases.

BACKGROUND: More than half of the patients with inflammatory bowel diseases are candidates for immunosuppressive therapy. However, even the most effective drugs used in inflammatory bowel disease are only successful in about two-thirds of patients. Adverse events limit their use in a further substantial proportion of patients. Recent research has focussed on the possibility of predicting a drugs' efficacy and/or toxicity by identifying polymorphic variants in the genes encoding enzymes involved in metabolic pathways. AIM: To highlight recent advances and limitations in the field of pharmacogenetics in inflammatory bowel disease. RESULTS: Recent pharmacogenetic studies have mainly focussed on immunosuppressive agents including corticosteroids, azathioprine, methotrexate and infliximab. Several polymorphic genes encoding enzymes involved in the metabolism of these drugs have been identified including the inosine triphosphate pyrophosphatase in thiopurine therapy, the methylene tetrahydrofolate reductase in methotrexate therapy and polymorphisms in apoptosis genes in infliximab therapy. However, at the present time, genotyping for the variants of the thiopurine methyltransferase gene, an enzyme important for the metabolism of the thiopurine drugs, is the only useful test in clinical practice. CONCLUSIONS: Although the field of pharmacogenetics in inflammatory bowel disease is promising most new targets have so far failed to translate into clinical practice. Future pharmaceutical trials should include pharmacogenetic research to test appropriate candidate genes in a prospective manner.

Anti-Inflammatory Agents↗
PubMed2006

Killer Ig-like receptor (KIR) genotype and HLA ligand combinations in ulcerative colitis susceptibility.

Killer immunoglobulin-like receptors (KIRs) are expressed on natural killer cells and some T-cell subsets and produce either activation or inhibitory signals upon binding with the appropriate human leucocyte antigen (HLA) ligand on target cells. Recent genetic association studies have implicated KIR genotype in the development of several inflammatory conditions. Ulcerative colitis (UC) is an inflammatory disorder of the colonic mucosa that results from an inappropriate activation of the immune system driven by host bacterial flora. We developed a polymerase chain reaction-sequence specific primer (SSP)-based assay to genotype 194 UC patients and 216 control individuals for 14 KIR genes, the HLA-Cw ligand epitopes of the KIR2D receptors and a polymorphism of the lectin-like-activating receptor NKG2D. Initial analysis found the phenotype frequency of KIR2DL2 and -2DS2 to be significantly increased in the UC cohort (P=0.030 and 0.038, respectively). Logistic regression analysis revealed a protective effect conferred by KIR2DL3 in the presence of its ligand HLA-Cw group 1 (P=0.019). These results suggest that KIR genotype and HLA ligand interaction may contribute to the genetic susceptibility of UC.

Base Sequence↗
PubMed2006

Lack of association of MYO9B genetic variants with coeliac disease in a British cohort.

BACKGROUND AND AIMS: Development of coeliac disease involves an interaction between environmental factors (especially dietary wheat, rye, and barley antigens) and genetic factors (there is strong inherited disease susceptibility). The known human leucocyte antigen (HLA)-DQ2 and -DQ8 association explains only a minority of disease heritability. A recent study in the Dutch population suggested that genetic variation in the 3' region of myosin IXB (MYO9B) predisposes to coeliac disease. MYO9B is a Rho family GTPase activating protein involved in epithelial cell cytoskeletal organisation. MYO9B is hypothesised to influence intestinal permeability and hence intestinal antigen presentation. METHODS: Four single nucleotide polymorphisms were chosen to tag all common haplotypes of the MYO9B 3' haplotype block (exons 15-27). We genotyped 375 coeliac disease cases and 1366 controls (371 healthy and 995 population based). All individuals were of White UK Caucasian ethnicity. RESULTS: UK healthy control and population control allele frequencies were similar for all MYO9B variants. Case control analysis showed no significant association of any variant or haplotype with coeliac disease. CONCLUSIONS: Genetic variation in MYO9B does not have a major effect on coeliac disease susceptibility in the UK population. Differences between populations, a weaker effect size than originally described, or possibly a type I error in the Dutch study might explain these findings.

Adolescent↗
PubMed2006

Long-term follow-up of strictureplasty for Crohn's disease.

BACKGROUND: Strictureplasty is an effective means of alleviating obstructive Crohn's disease while conserving bowel length. The aim of this study was to establish long-term outcomes of strictureplasty. METHODS: Between 1978 and 2003, 479 strictureplasties were performed in 100 patients during 159 operations. Information on Crohn's disease, medical therapy, laboratory indices, surgical details, complication rates and outcomes was recorded. The primary endpoint was abdominal reoperation. RESULTS: Mean follow-up was 85.1 (range 0.2-240.9) months. The overall morbidity rate was 22.6 per cent, with septic complications in 11.3 per cent, obstruction in 4.4 per cent and gastrointestinal haemorrhage in 3.8 per cent. The 30-day mortality rate was 0.6 per cent and the procedure-related series mortality rate 3.0 per cent. Perioperative parenteral nutrition was the only marker for morbidity (P < 0.001). Reoperation rates were 52 per cent at a mean of 40.2 (range 0.2-205.8) months after a first, 56 per cent at 26.1 (range 3.5-63.5) months after a second, 86 per cent at 27.4 (range 1.4-74.5) months after a third, and 62.5 per cent at 25.9 (range 7.3-70.5) months following a fourth strictureplasty procedure. The major risk factor for reoperation was young age (P < 0.001). CONCLUSION: Long-term follow-up has confirmed the safety of strictureplasty in Crohn's disease. Morbidity is appreciable, although the surgical mortality rate is low. Reoperation rates are comparable following first and repeat strictureplasty procedures.

Adolescent↗
PubMed2006

IFN gamma and CXCR-1 gene polymorphisms in idiopathic bronchiectasis.

Idiopathic bronchiectasis is a disease of chronic, bacterial lung infection, unresolving inflammation and progressive lung damage. Bronchiectasis can be associated with autoimmune diseases including ulcerative colitis. Defects of both innate and adaptive immunity have been proposed. The airway inflammation is characterized by interleukin-8 (IL-8) expression and infiltration by neutrophils and T cells. Here we investigated two candidate gene polymorphisms that may contribute to disease susceptibility: a CXCR-1 (+2607 G/C) gene polymorphism that is implicated in IL-8 binding and neutrophil trafficking as well as the interferon-gamma (IFNgamma) (+874 T/A) polymorphism which is linked to levels of IFNgamma production. These polymorphisms were distributed similarly in the idiopathic bronchiectasis group and controls, suggesting that these two candidate gene polymorphisms are not associated with disease susceptibility.

Alleles↗
PubMed2005

Antagonists and non-toxic variants of the dominant wheat gliadin T cell epitope in coeliac disease.

BACKGROUND: Coeliac disease (CD) is due to an inappropriate T cell mediated response to specific gluten peptides. Measured by interferon gamma (IFN-gamma) ELISPOT, about half of the gliadin specific T cells induced with in vivo wheat gluten exposure in HLA-DQ2+ CD are specific for an alpha/beta-gliadin peptide (p57-73 QE65; QLQPFPQPELPYPQPQS) that includes two overlapping T cell epitopes (PFPQPELPY and PQPELPYPQ). AIM: To define minimally substituted variants of p57-73 QE65 universally devoid of IFN-gamma stimulatory capacity but capable of antagonising IFN-gamma secretion from polyclonal T cells specific for p57-73 QE65. METHODS: Peripheral blood mononuclear cells collected from 75 HLA-DQ2+ CD patients after in vivo gluten challenge were used in overnight ELISPOT assays to screen 218 single or double substituted variants of p57-73 QE65 for cytokine stimulatory and antagonist activity. RESULTS: The region p60-71 (PFPQPELPYPQP) and especially p64-67 (PELP) was sensitive to substitution. Twelve substitutions in p64-67 stimulated no IFN-gamma ELISPOT response. Among 131 partial agonists identified, 45 produced statistically significant inhibition of IFN-gamma ELISPOT responses when cocultured in fivefold excess with p57-73 QE65 (n = 10). Four substituted variants of p57-73 QE65 were inactive by IFN-gamma ELISPOT but consistently antagonised IFN-gamma ELISPOT responses to p57-73 QE65, and also retained interleukin 10 stimulatory capacity similar to p57-73 QE65. CONCLUSIONS: Altered peptide ligands of p57-73 QE65, identified using polyclonal T cells from multiple HLA-DQ2+ CD donors, have properties in vitro that suggest that a single substitution to certain alpha/beta-gliadins could abolish their capacity to stimulate IFN-gamma from CD4 T cells and also have anti-inflammatory or protective effects in HLA-DQ2+ CD.

Adult↗
PubMed2005

Synergy between TLR9 and NOD2 innate immune responses is lost in genetic Crohn's disease.

BACKGROUND: Nucleotide binding oligomerisation domain 2 (NOD2; also known as CARD15) mutations are associated with Crohn's disease but how mutations cause disease is poorly understood. Innate immune responses are reportedly enhanced by combined NOD2 ligand (muramyl dipeptide, MDP) and Toll-like receptor 4 ligand (TLR4, lipopolysaccharide) stimulation. Intestinal TLR signalling has a dual role-maintaining intestinal homeostasis and protection from injury as well as initiating inflammatory responses. TLR9 is functional in the intestinal epithelium where it is most strongly expressed in Paneth cells. AIMS: To study possible interactions between CpG DNA (TLR9 ligand) and MDP using primary human cells of differing NOD2 genotypes. SUBJECTS: NOD2 wild-type healthy controls (n = 7) and NOD2 homozygous Crohn's disease patients (n = 19), age and sex matched. METHODS: Peripheral blood mononuclear cells were stimulated with CpG DNA and MDP. Cytokines were measured by enzyme linked immunosorbent assay. RESULTS: Tumour necrosis factor alpha (TNF-alpha) and interleukin 8 (IL-8) responses to CpG DNA were similar in NOD2 wild-type and homozygous mutant cells. Concomitant NOD2 stimulation had a marked synergistic effect on CpG DNA induced TNF-alpha responses at 10-100 ng/ml MDP. A mean 2.1-fold increase in CpG DNA induced TNF-alpha responses and a mean 3.7-fold increase in IL-8 responses were observed in NOD2 wild-type cells with 10 ng/ml MDP. This effect was abolished in NOD2 homozygous cells. CONCLUSIONS: NOD2 stimulation normally enhances innate immune responses to CpG DNA. This marked synergistic effect is lost in Crohn's disease patients homozygous for NOD2 mutations, with implications for TLR mediated intestinal homeostasis and inflammation.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed2005

Oral methotrexate in ulcerative colitis.

BACKGROUND: We performed an audit of methotrexate for ulcerative colitis, because efficacy is unclear. Aim : To investigate the role of methotrexate in the management of ulcerative colitis. METHODS: Patients with ulcerative colitis treated with oral methotrexate at the inflammatory bowel disease clinics of Oxford and Wycombe General Hospital, UK, were evaluated. Efficacy was defined by remission (complete steroid withdrawal for >3 months) and response (good, partial or nil, proportionate reduction of steroids). RESULTS: There were 50 patients (42 ulcerative colitis alone; eight had rheumatoid arthritis associated with ulcerative colitis and were analysed separately). Indications for methotrexate in ulcerative colitis alone were azathioprine intolerance (31 of 42) and lack of benefit from azathioprine (11 of 42). The mean dose of methotrexate in ulcerative colitis alone was 19.9 mg/week for a median of 30 weeks (range: 7-395). Remission occurred in 42%. The response was good in 54% and partial in 18%. Side-effects occurred in 23%; 10% stopped treatment because of side-effects. Of those treated with methotrexate because of treatment failure with azathioprine, three of 11 achieved remission, but four came to colectomy within 90 days of starting methotrexate. The colitis remained in remission in seven of eight of those with RA treated with methotrexate and ulcerative colitis (mean dose 15.0 mg/week). CONCLUSION: Oral methotrexate (approximately 20 mg/week) is well-tolerated and moderately effective in steroid-dependent or steroid-refractory patients with ulcerative colitis.

Adolescent↗
PubMed2005

Enhanced metabolic cycling in subjects after colonic resection for ulcerative colitis.

Colonic resection leads to insulin resistance, but the mechanisms are unknown. We used an integrated approach to examine adipose tissue and skeletal muscle metabolism in patients lacking a colon. Ten healthy colectomized patients having undergone surgery for ulcerative colitis and 10 matched control subjects were studied with a hyperinsulinemic-euglycemic clamp to measure insulin sensitivity, an arteriovenous sampling meal tolerance study to measure postprandial substrate flux across adipose tissue and skeletal muscle, and adipose tissue and skeletal muscle biopsies to quantify the expression of genes involved in glucose and lipid metabolism. Colectomized subjects exhibited lower insulin sensitivity (homeostatic model assessment model, 33% reduction, P = 0.03; minimal model, 29% reduction, P = 0.05), elevated aldosterone (9-fold, P = 0.003), leptin (2.2-fold, P = 0.03), and an increased rate of nonesterified fatty acid and glycerol release from adipose tissue (P = 0.02) especially in the late postprandial period. The uptake of fatty acids into muscle was also significantly increased (P = 0.007), as were muscle CD36 and LPL mRNA expression compared with controls. In adipose tissue, hormone-sensitive lipase mRNA expression was increased (P = 0.015), whereas peroxisome proliferator-activated receptor-gamma expression was decreased (P = 0.02), as was that of CD36 (P = 0.001). In this study, alterations in fatty acid metabolism after colonic resection altered may have contributed to the impairment of insulin sensitivity.

Adult↗
PubMed2005

Cancer surveillance in ulcerative colitis.

BACKGROUND: Patients with ulcerative colitis are at a higher risk of developing colorectal cancer than those without the disease. Surveillance programmes are used routinely to detect dysplasia and cancer in patients with ulcerative colitis. However, such programmes are poorly effective. This article discusses possible improvements suggested by recent research. METHODS: Papers relating to cancer associated with ulcerative colitis and surveillance programmes to detect such cancer were identified using Medline searches. Further papers were identified from the reference lists of identified papers. RESULTS: The probability of cancer for all patients with ulcerative colitis regardless of disease extent was 2 per cent at 10 years, 8 per cent at 20 years and 18 per cent at 30 years; the overall prevalence of colorectal cancer in any patient was 3.7 per cent. Indications for colonoscopic surveillance are extensive disease for 8-10 years, especially in those with active inflammation, a family history of colorectal cancer and primary sclerosing cholangitis. Problems affecting surveillance include the diagnosis of dysplasia, difficulty in differentiating 'sporadic' adenomas from a dysplasia-associated lesion or mass, and decision making based on surveillance findings. Molecular genetic and endoscopic advances to alleviate these problems are discussed. CONCLUSION: Rates of detection of dysplasia can be improved by chromoendoscopy. Molecular genetics has the potential to identify patients most at risk of cancer and can differentiate between different types of lesion.

Aneuploidy↗
PubMed2005

Long-term function after restorative proctocolectomy.

PURPOSE: Early functional outcome after restorative proctocolectomy and formation of an ileoanal pouch is known to be good, but there are minimal data on the long-term function of the pouch. The aim of this study was to look at the long-term functional outcome in patients who had undergone restorative proctocolectomy and formation of an ileoanal pouch. METHODS: A total of 151 consecutive patients (96 males, 55 females) who underwent ileoanal pouch surgery between April 1983 and May 1993 were identified. Functional outcomes from the previous 12 months were appraised by a standardized questionnaire. RESULTS: The median age at surgery was 31 years (range, 6-63 years), with a median follow-up of 142 months (range, 100-221 months). Eighteen patients have had their pouches excised, with another patient being defunctioned. Therefore 19 patients (13 percent) had suffered pouch failure. Altogether, 115 patients were available for follow-up, and 98 patients (85 percent) returned questionnaires. The median pouch-emptying frequency was five times (range, 1-17) during the day and one time (range, 0-6) at night. A total of 74 percent of patients had perfect continence during the day. Most of the patients had no life-style restrictions related to the pouch, and 98 percent of patients would recommend a pouch to others. CONCLUSIONS: Long-term functional outcome after ileoanal pouch surgery is good in most patients. For patients requiring proctocolectomy, ileoanal pouch surgery can now be recommended as an excellent long-term option.

Adolescent↗
PubMed2005

Risks and benefits of azathioprine therapy.

The risk of lymphoma may be increased by about fourfold in patients with inflammatory bowel disease treated with thiopurines. The increased risk could be a result of the medications, the severity of the underlying disease, or a combination of the two.

Antimetabolites↗
PubMed2005

T cells in peripheral blood after gluten challenge in coeliac disease.

BACKGROUND: Current understanding of T cell epitopes in coeliac disease (CD) largely derives from intestinal T cell clones in vitro. T cell clones allow identification of gluten peptides that stimulate T cells but do not quantify their contribution to the overall gluten specific T cell response in individuals with CD when exposed to gluten in vivo. AIMS: To determine the contribution of a putative dominant T cell epitope to the overall gliadin T cell response in HLA-DQ2 CD in vivo. PATIENTS: HLA-DQ2+ individuals with CD and healthy controls. METHODS: Subjects consumed 20 g of gluten daily for three days. Interferon gamma (IFN-gamma) ELISPOT was performed using peripheral blood mononuclear cells (PBMC) to enumerate and characterise peptide and gliadin specific T cells before and after gluten challenge. RESULTS: In 50/59 CD subjects, irrespective of homo- or heterozygosity for HLA-DQ2, IFN-gamma ELISPOT responses for an optimal concentration of A-gliadin 57-73 Q-E65 were between 10 and 1500 per million PBMC, equivalent to a median 51% of the response for a "near optimal" concentration of deamidated gliadin. Whole deamidated gliadin and gliadin epitope specific T cells induced in peripheral blood expressed an intestinal homing integrin (alpha4beta7) and were HLA-DQ2 restricted. Peripheral blood T cells specific for A-gliadin 57-73 Q-E65 are rare in untreated CD but can be predictably induced two weeks after gluten exclusion. CONCLUSION: In vivo gluten challenge is a simple safe method that allows relevant T cells to be analysed and quantified in peripheral blood by ELISPOT, and should permit comprehensive high throughput mapping of gluten T cell epitopes in large numbers of individuals with CD.

Adult↗
PubMed2004

Human keratin 8 mutations that disturb filament assembly observed in inflammatory bowel disease patients.

We have identified miss-sense mutations in keratin 8 in a subset of patients with inflammatory bowel disease (Crohn disease and ulcerative colitis). Inflammatory bowel diseases are a group of disorders that are polygenic in origin and involve intestinal epithelial breakdown. We investigated the possibility that these keratin mutations might contribute to the course of the disease by adversely affecting the keratin filament network that provides mechanical support to cells in epithelia. The mutations (Gly62 to Cys, Ile63 to Val and Lys464 to Asn) all lie outside the major mutation hotspots associated with severe disease in epidermal keratins, but using a combination of in vitro and cell culture assays we show that they all have detrimental effects on K8/K18 filament assembly in vitro and in cultured cells. The G62C mutation also gives rise to homodimer formation on oxidative stress to cultured intestinal epithelial cells, and homodimers are known to be polymerization incompetent. Impaired keratin assembly resulting from the K8 mutations found in some inflammatory bowel disease patients would be predicted to affect the maintenance and re-establishment of mechanical resilience in vivo, as required during keratin cytoskeleton remodeling in cell division and differentiation, which may lead to epithelial fragility in the gut. Simple epithelial keratins may thus be considered as candidates for genes contributing to a risk of inflammatory bowel disease.

Actin Cytoskeleton↗
PubMed2004

Randomized, double-blind, placebo-controlled trial of oral aloe vera gel for active ulcerative colitis.

BACKGROUND: The herbal preparation, aloe vera, has been claimed to have anti-inflammatory effects and, despite a lack of evidence of its therapeutic efficacy, is widely used by patients with inflammatory bowel disease. AIM: To perform a double-blind, randomized, placebo-controlled trial of the efficacy and safety of aloe vera gel for the treatment of mildly to moderately active ulcerative colitis. METHODS: Forty-four evaluable hospital out-patients were randomly given oral aloe vera gel or placebo, 100 mL twice daily for 4 weeks, in a 2 : 1 ratio. The primary outcome measures were clinical remission (Simple Clinical Colitis Activity Index </= 2), sigmoidoscopic remission (Baron score </= 1) and histological remission (Saverymuttu score </= 1). Secondary outcome measures included changes in the Simple Clinical Colitis Activity Index (improvement was defined as a decrease of >/= 3 points; response was defined as remission or improvement), Baron score, histology score, haemoglobin, platelet count, erythrocyte sedimentation rate, C-reactive protein and albumin. RESULTS: Clinical remission, improvement and response occurred in nine (30%), 11 (37%) and 14 (47%), respectively, of 30 patients given aloe vera, compared with one (7%) [P = 0.09; odds ratio, 5.6 (0.6-49)], one (7%) [P = 0.06; odds ratio, 7.5 (0.9-66)] and two (14%) [P < 0.05; odds ratio, 5.3 (1.0-27)], respectively, of 14 patients taking placebo. The Simple Clinical Colitis Activity Index and histological scores decreased significantly during treatment with aloe vera (P = 0.01 and P = 0.03, respectively), but not with placebo. Sigmoidoscopic scores and laboratory variables showed no significant differences between aloe vera and placebo. Adverse events were minor and similar in both groups of patients. CONCLUSION: Oral aloe vera taken for 4 weeks produced a clinical response more often than placebo; it also reduced the histological disease activity and appeared to be safe. Further evaluation of the therapeutic potential of aloe vera gel in inflammatory bowel disease is needed.

Administration, Oral↗
PubMed2004

Perianal Crohn's disease.

BACKGROUND: The management of perianal Crohn's disease is difficult. A wide variety of treatment options exist although few are evidence based. METHODS: A search was conducted using the National Library of Medicine for articles on perianal Crohn's disease and its incidence, classification, assessment and management. RESULTS AND CONCLUSION: Perianal Crohn's disease can manifest as skin tags, ulcers, fissures, abscesses, fistulas or stenoses. Improved radiological imaging with endoanal anal ultrasonography and magnetic resonance imaging has improved its assessment and may be used to predict outcome after surgery. Many treatment options exist. During acute complications they are generally aimed at resolving the immediate problem and limiting damage to anal and perianal tissues; this may be a 'bridge' to definitive treatment. The likelihood of success of definitive treatment must be weighed against the risk of complications, especially faecal incontinence.

Aminosalicylic Acids↗