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Dive into the research topics where Jon O. Kristinsson is active.

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Featured researches published by Jon O. Kristinsson.


International Journal of Cancer | 2013

Barrett associated MHC and FOXF1 variants also increase esophageal carcinoma risk

Polat Dura; Elke M. van Veen; Jody Salomon; Rene H. M. te Morsche; Hennie M.J. Roelofs; Jon O. Kristinsson; Theo Wobbes; Ben J. Witteman; Adriaan C. Tan; Joost P. H. Drenth; Wilbert H.M. Peters

Barretts esophagus, with gastroesophageal reflux disease and obesity as risk factors, predisposes to esophageal adenocarcinoma (EAC). Recently a British genome wide association study identified two Barretts esophagus susceptibility loci mapping within the major histocompatibility complex (MHC; rs9257809) and closely to the Forkhead‐F1 (FOXF1; rs9936833) coding gene. An interesting issue is whether polymorphisms associated with Barretts esophagus, are also implicated in esophageal carcinoma (EC), and more specifically EAC genesis. Assessing the individual genetic susceptibility can help identify high risk patients more prone to benefit from surveillance programs. Our hypothesis: Barrett associated MHC and FOXF1 variants modify EC risk in Caucasians. In a Dutch case‐control study, 431 patients with EC and 605 healthy controls were included. Polymorphisms at chromosomes 6p21 (MHC) and 16q24 (FOXF1) were determined by means of real‐time polymerase chain reaction (RT‐PCR). Logistic regression analysis was used to calculate odds ratios with 95% confidence intervals. The FOXF1 rs9936833 variant C allele was associated with an increased EAC susceptibility; OR, [95% CI]; 1.21, [0.99–1.47]. A sex‐stratified analysis revealed a similar association in males; 1.24 [1.00–1.55]. The variant MHC rs9257809 G allele as well as the MHC heterozygous AG genotype significantly increased ESCC risk; 1.76 [1.16–2.66] and 1.74 [1.08–2.80], respectively. Sex‐stratification showed that the variant G allele was especially present in female patients; 2.32 [1.04–5.20]. In conclusion, this study provides evidence that MHC rs9257809 and FOXF1 rs9936833 variants, associated with Barretts esophagus, also increase ESCC and EAC susceptibility in Caucasians. FOX proteins are transcription factors involved in organogenesis of the GI tract, while MHC haplotypes are strongly associated with smoking behavior, a crucial risk factor for ESCC. Assessing the individual genetic susceptibility can help identify high risk patients more prone to benefit from (Barrett) surveillance programs.


European Journal of Cancer Prevention | 2013

GWAS-uncovered SNPs in PLCE1 and RFT2 genes are not implicated in Dutch esophageal adenocarcinoma and squamous cell carcinoma etiology.

Polat Dura; Caro V.V. Bregitha; Rene H. M. te Morsche; Hennie M.J. Roelofs; Jon O. Kristinsson; Theo Wobbes; Ben J. Witteman; Adriaan C. Tan; Joost P. H. Drenth; Wilbert H.M. Peters

Susceptibility to esophageal carcinoma (EC) is influenced by the interaction between genetic and environmental factors. To clarify the etiology of EC, several genome-wide association studies have identified single nucleotide polymorphisms (SNPs) in PCLE1 and RFT2 genes as esophageal squamous cell carcinoma (ESCC) susceptibility loci in Asian populations. This study aimed to determine whether these SNPs also modify the risk of esophageal adenocarcinoma (EAC) and ESCC in western populations of Caucasian ethnicity. A European case–control study including 349 EC patients and 580 controls matched for age, sex, geographical location, and race was carried out. The SNPs rs2274223 in the PCLE1 gene at chromosome 10q23 and rs13042395 in the RFT2 gene at chromosome 20p13 were determined using PCR. Genotype distributions were compared between patients and controls, and odds ratios with 95% confidence intervals were calculated. The total EC group included 86 patients with ESCC and 258 patients with EAC. The distribution of PLCE1 and RFT2 genotypes did not differ between patients with EAC or ESSC, and the controls. In contrast to the modulation of the risk of ESCC in Asians, it is unlikely that the PLCE1 rs2274223 and RFT2 13042395 SNPs play a role in EAC or ESCC susceptibility in Dutch Caucasians.


International Journal of Oncology | 2012

High enzyme activity UGT1A1 or low activity UGT1A8 and UGT2B4 genotypes increase esophageal cancer risk

Polat Dura; Jody Salomon; Rene H. M. te Morsche; Hennie M.J. Roelofs; Jon O. Kristinsson; Theo Wobbes; Ben J. Witteman; Adriaan C. Tan; Joost P. H. Drenth; Wilbert H.M. Peters

Esophageal cancer (EC) has a globally increasing incidence with poor curative treatment options and survival rates. Environmental and dietary factors have crucial roles in esophageal carcinogenesis. Polymorphisms in the UGT genes, a superfamily of enzymes essential for the detoxification of carcinogens, may alter enzyme activity and subsequently may play a role in EC etiology. Rather than solely establishing differences in genotype distribution, we investigated whether functional polymorphisms in UGT genes that can predict enzyme activity in vivo, may influence EC risk. A case-control study including 351 Caucasian EC patients and 592 Caucasian controls was conducted and polymorphisms in seven UGT genes were determined, using the polymerase chain reaction. On the basis of allelic in vitro enzyme activity measurements, genotypes were categorized according to their predicted in vivo enzyme activity into high, medium and low categories. Predicted enzyme activity groups were combined and compared between patients and controls. The UGT1A1 and UGT1A8 predicted high enzyme activity genotypes were significantly more (OR=1.62; 95% CI, 1.02-2.56) and less frequent (OR=0.36; 95% CI, 0.15-0.84) among patients with esophageal squamous cell carcinoma (ESCC), respectively. High (OR=0.42; 95% CI, 0.22-0.84) and medium (OR=0.25; 95% CI, 0.12-0.52) activity UGT2B4 genotypes were significantly less often present in ESCC patients. No association was detected between UGT genotypes and esophageal adenocarcinoma (EAC) risk. Polymorphisms in UGT genes, resulting in altered enzyme activity genotypes, do not seem modifiers of EAC risk. However, the predicted high activity UGT1A1 genotype, associated with low serum levels of the antioxidant bilirubin, was associated with an increased ESCC risk. The UGT1A8 and UGT2B4 genotypes associated with decreased predicted enzyme activities, were significantly associated with an increased risk of ESCC, probably by a decreased detoxification of carcinogens.


BMC Gastroenterology | 2007

Gastroparesis in patients with inactive Crohn's disease: a case series

Jon O. Kristinsson; Wim P.M. Hopman; Wim J.G. Oyen; Joost P. H. Drenth

BackgroundFew studies have described patients with foregut dysmotility in inflammatory bowel disease. The aim of this case series was to evaluate clinical characteristics of 5 patients with inflammatory bowel disease and symptoms and signs of upper gut dysmotility.Case presentationsWe describe a series of four patients with Crohns disease and one with indeterminate colitis who presented with severe symptoms and signs of gastroparesis. We reviewed medical records of all cases. Gastric emptying of a solid meal was assessed by scintigraphy. Small bowel enteroclysis, gastroduodenoscopy and colonoscopy with biopsies were performed to estimate the activity of the disease and to exclude organic obstruction. None of the patients had any signs of active inflammation or stricture. All of the patients had markedly delayed gastric emptying with a mean t 1/2 of 234 minutes (range 110–380 minutes; normal values 54–94 minutes).ConclusionClinicians should consider impaired gastric emptying when evaluating patients with Crohns disease and severe symptoms of upper gut dysmotility, which cannot be attributed to active inflammation or organic obstruction of the digestive tract. Symptoms in these patients are refractory to various therapeutic interventions including tube feeding and gastric surgery.


Oncology Reports | 2012

EPHX1 polymorphisms do not modify esophageal carcinoma susceptibility in Dutch Caucasians.

Polat Dura; Caro V.V. Bregitha; Rene H. M. te Morsche; Hennie M.J. Roelofs; Jon O. Kristinsson; Theo Wobbes; Ben J. Witteman; Adriaan C. Tan; Joost P. H. Drenth; Wilbert H.M. Peters

Esophageal cancer (EC) has a globally increasing incidence with poor curative treatment options and survival rates. Crucial risk factors are exposure to toxins or carcinogens. Microsomal epoxide hydrolase (mEH) is a biotransformation enzyme essential for the detoxification of xenobiotics. Polymorphisms in exon 3 and exon 4 of the microsomal epoxide hydrolase gene (EPHX1) modify catalytic activity of this enzyme and subsequently may play a role in EC etiology. This case-control study investigated whether these polymorphisms in the EPHX1 gene influence esophageal cancer susceptibility in a Dutch Caucasian population. A case-control study including 349 Caucasian EC patients and 581 Caucasian healthy controls was conducted and the polymorphisms Tyr113His (exon 3) and His139Arg (exon 4) in the EPHX1 gene were determined, using polymerase chain reaction. The distribution of exon 3 and exon 4 genotypes were compared between cases and controls. Analyses included a stratification according to tumor histology; esophageal adenocarcinoma (EAC) or squamous cell carcinoma (ESCC). Furthermore, on the basis of allelic in vitro enzyme activity assays, exon 3 and 4 genotypes were combined and categorized according to their predicted high, medium or low enzyme activity. Homozygosity and heterozygosity for both exon 3 and 4 polymorphisms were correlated with a decreased esophageal squamous cell carcinoma risk. Heterozygosity and homozygosity for both polymorphisms correlated with an increased and a decreased esophageal adenocarcinoma risk, respectively. Predicted intermediate and high activity genotypes were risk and protective factors for esophageal squamous cell carcinoma and esophageal adenocarcinoma, respectively. However, none of these associations were statistically significant. In conclusion, the polymorphisms in exon 3 and exon 4 of the EPHX1 gene do not seem to be modifiers of esophageal squamous cell carcinoma or esophageal adenocarcinoma risk in Dutch Caucasians.


BMC Gastroenterology | 2013

No role for glutathione S-transferase genotypes in Caucasian esophageal squamous cell or adenocarcinoma etiology: an European case-control study

Polat Dura; Jody Salomon; Rene H. M. te Morsche; Hennie M.J. Roelofs; Jon O. Kristinsson; Theo Wobbes; Ben J. Witteman; Adriaan C. Tan; Joost P. H. Drenth; Wilbert H.M. Peters

BackgroundIdentifying and monitoring high-risk patients can aid the prevention of esophageal cancer (EC). The interaction of environmental risk factor exposure and genetic susceptibility may contribute to the etiology of EC. Biotransformation enzymes such as Glutathione S-Transferases (GSTs ) detoxify mutagenic and genotoxic compounds and therefore control the rate of detoxification of carcinogens. Functional polymorphisms in the genes coding for GSTs alter their enzyme activity in vitro, and were reported to modify EC risk in Asians. We hypothesized that altered enzyme activity GST genotypes influence the susceptibility for esophageal adeno- (EAC) and squamous cell carcinoma (ESCC) in Caucasians.MethodsWe performed a case–control study including 440 Caucasian patients with EC and 592 healthy Caucasian controls matched for age and sex. Functional polymorphisms were selected and genotypes were determined in GST classes Alpha, Mu, Theta and Pi by means of polymerase chain reaction. Genotypes were classified into predicted high, intermediate and low enzyme activity categories based on in vitro activity data. The distribution of the activity genotypes were compared between patients with EAC or ESCC, and controls. Odds ratios (OR) with 95% confidence intervals (CI) were calculated by logistic regression analyses. Gene-gene interactions were tested and for comparison purposes, the predicted low and intermediate activity genotypes were combined. Genotypes with similar risks for EAC or ESCC were combined and analyzed for multiplicative effects.ResultsOur analyses includes 327 patients with EAC and 106 patients with ESCC. Low or intermediate activity enzyme genotypes for GSTM1, GSTA1, GSTP1 I105V and A114V as well as for GSTT1, did not significantly modify the risk for ESCC or EAC in our Dutch population.ConclusionFunctional genotypes in GST genes are not involved in EAC or ESCC susceptibility in Caucasians, in contrast to results on ESCC from Asia or Africa.


Journal of Human Genetics | 2013

Polymorphisms in alcohol-metabolizing enzymes and esophageal carcinoma susceptibility : a Dutch Caucasian case-control study

Polat Dura; T. Berkers; E.M. van Veen; Jody Salomon; R.H.M. te Morsche; Hennie M.J. Roelofs; Jon O. Kristinsson; Theo Wobbes; Ben J. Witteman; Adriaan C. Tan; J.P.H. Drenth; Wilbert H.M. Peters

Esophageal cancer (EC), mainly consisting of squamous cell carcinoma (ESCC) in the Eastern world and adenocarcinoma (EAC) in the Western world, is strongly associated with dietary factors such as alcohol use. We aimed to clarify the modifying role in EC etiology in Caucasians of functional genotypes in alcohol-metabolizing enzymes. In all, 351 Caucasian patients with EC and 430 matched controls were included and polymorphisms in CYP2E1, ADH and near ALDH2 genes were determined. In contrast to the results on ESCC in mainly Asian studies, we found that functional genotypes of alcohol-metabolizing enzymes were not significantly associated with EAC or ESCC in an European population.


Frontline Gastroenterology | 2015

Clinical trial: free fatty acid suppositories compared with enema as bowel preparation for flexible sigmoidoscopy

Orri Thor Ormarsson; Gudrun Marta Asgrimsdottir; Thorsteinn Loftsson; Einar Stefánsson; Jon O. Kristinsson; Sigrún H. Lund; Einar Björnsson

Objectives The purpose of this trial was to evaluate the efficacy and safety of recently developed suppositories containing free fatty acids as a bowel-cleansing agent prior to flexible sigmoidoscopy and compare them with Klyx (docusate sodium/sorbitol). Design A controlled, non-inferiority, single-blind, randomised study on outpatients undergoing flexible sigmoidoscopy. Setting Department of Gastroenterology, Landspitali-University Hospital and endoscopic clinic. Patients 53 outpatients undergoing flexible sigmoidoscopy. Intervention Participants were randomised to receive either free fatty acid suppositories (28) or a standard bowel preparation with Klyx enema (25). In the study group, two suppositories were administered the evening before as well as 2 h prior to the sigmoidoscopy. In the control group, Klyx enema (120 mL) was administered the evening before and repeated 2 h prior to the procedure. Main outcome measurements Quality of the bowel cleansing, height of scope insertion and safety. Results The mean height of scope insertion and bowel cleansing was 43 cm (SD=13.4) in the study group and 48 cm (SD=10.4) in the control group (NS). The investigating physicians were less satisfied with the bowel preparation in the study group compared with the control group with a difference of 20% (p<0.016). The amount of faeces noted in the rectum was similar in both groups with no significant difference (p<0.56). No serious side effects, toxic reaction or irritation were observed. Conclusions The suppositories are well tolerated with no significant side effects. The suppositories had distinct bowel emptying effect and as effective as Klyx in rectal cleansing. Although physicians satisfaction was slightly lower, the height of scope insertion was similar. Trial registration number EudraCT nr.: 2010-018761-35.


Gastroenterology | 2012

Su1843 High Enzyme Activity UGT1A1 or Low Activity Ugt1a8 and Ugt2b4 Genotypes Increase Esophageal Cancer Risk

Polat Dura; Jody Salomon; Rene H. M. te Morsche; Hennie M.J. Roelofs; Jon O. Kristinsson; Theo Wobbes; Ben J. Witteman; Adriaan C. Tan; Joost P. H. Drenth; Wilbert H.M. Peters

Esophageal cancer (EC) has a globally increasing incidence with poor curative treatment options and survival rates. Environmental and dietary factors have crucial roles in esophageal carcinogenesis. Polymorphisms in the UGT genes, a superfamily of enzymes essential for the detoxification of carcinogens, may alter enzyme activity and subsequently may play a role in EC etiology. Rather than solely estab- lishing differences in genotype distribution, we investigated whether functional polymorphisms in UGT genes that can predict enzyme activity in vivo, may influence EC risk. A case-control study including 351 Caucasian EC patients and 592 Caucasian controls was conducted and polymorphisms in seven UGT genes were determined, using the polymerase chain reaction. On the basis of allelic in vitro enzyme activity measurements, genotypes were categorized according to their predicted in vivo enzyme activity into high, medium and low categories. Predicted enzyme activity groups were combined and compared between patients and controls. The UGT1A1 and UGT1A8 predicted high enzyme activity genotypes were significantly more (OR=1.62; 95% CI, 1.02-2.56) and less frequent (OR=0.36; 95% CI, 0.15-0.84) among patients with esophageal squamous cell carcinoma (ESCC), respectively. High (OR=0.42; 95% CI, 0.22-0.84) and medium (OR=0.25; 95% CI, 0.12-0.52) activity UGT2B4 genotypes were signifi - cantly less often present in ESCC patients. No association was detected between UGT genotypes and esophageal adenocar- cinoma (EAC) risk. Polymorphisms in UGT genes, resulting in altered enzyme activity genotypes, do not seem modifiers of EAC risk. However, the predicted high activity UGT1A1 genotype, associated with low serum levels of the antioxidant bilirubin, was associated with an increased ESCC risk. The UGT1A8 and UGT2B4 genotypes associated with decreased predicted enzyme activities, were significantly associated with an increased risk of ESCC, probably by a decreased detoxifi - cation of carcinogens.


Scandinavian Journal of Gastroenterology | 2018

Incidence, diagnostic, treatment and outcome of patients diagnosed with cancer of the pancreas during 1986–2009: a population-based study

Sara B. Jonsdottir; Gunnar Juliusson; Jon O. Kristinsson; Johann P. Hreinsson; Jon G. Jonasson; Einar S. Björnsson

Abstract Objective: Limited data exist on the changes in the epidemiology of pancreatic cancer and outcomes over the last decades in population-based cohorts. We aimed to compare the incidence of pancreatic cancer, diagnostic, treatment and survival among patients diagnosed over the period 1986–2009. Materials and methods: A retrospective, nationwide, population-based study. All patients diagnosed with pancreatic cancer in Iceland in two periods, 1986–1997 (P1) and 1998–2009 (P2) were identified through the Icelandic Cancer Registry and relevant clinical information obtained from medical records. Results: A total of 645 patients were identified, 296 in P1 and 349 in P2 (NS). The incidence during P1 was 6.8 per 100,000 inhabitants and 6.2 during P2 (NS). Among biopsy-proven cancers, adenocarcinoma was diagnosed in 89% of the cases in P1 and in P2 in 93% of the cases. Overall 38 (14%) in P1 underwent resection and 22 (7%) in P2 (p < .0004). Patients diagnosed in P2 had longer survival at 6 months (p = .015, log-rank test) and one year (p = .0206) after diagnosis. A total of 4/296 (1.4%) in P1 survived more than 5 years and 3/349 (0.9%) in P2 (NS). Conclusions: The incidence among patients with pancreatic cancer in Iceland did not show major changes during the last 20 years. Diagnostic approach has changed considerably demonstrating more patients that are not ‘resectable’. Survival rate at 6 months and one year has improved over the last two decades whereas the 5-year prognosis has not improved.

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Ben J. Witteman

Wageningen University and Research Centre

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Joost P. H. Drenth

Radboud University Nijmegen

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Polat Dura

Radboud University Nijmegen

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Theo Wobbes

Radboud University Nijmegen

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Jody Salomon

Radboud University Nijmegen

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