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01 mei 2010, Contains fulltext : 89305.pdf (publisher's version ) (Closed access), Smoking is a common risk factor for many diseases. We conducted genome-wide association meta-analyses for the number of cigarettes smoked per day (CPD) in smokers (n = 31,266) and smoking initiation (n = 46,481) using samples from the ENGAGE Consortium. In a second stage, we tested selected SNPs with in silico replication in the Tobacco and Genetics (TAG) and Glaxo Smith Kline (Ox-GSK) consortia cohorts (n = 45,691 smokers) and assessed some of those in a third sample of European ancestry (n = 9,040). Variants in three genomic regions associated with CPD (P < 5 x 10(-8)), including previously identified SNPs at 15q25 represented by rs1051730[A] (effect size = 0.80 CPD, P = 2.4 x 10(-69)), and SNPs at 19q13 and 8p11, represented by rs4105144[C] (effect size = 0.39 CPD, P = 2.2 x 10(-12)) and rs6474412-T (effect size = 0.29 CPD, P = 1.4 x 10(-8)), respectively. Among the genes at the two newly associated loci are genes encoding nicotine-metabolizing enzymes (CYP2A6 and CYP2B6) and nicotinic acetylcholine receptor subunits (CHRNB3 and CHRNA6), all of which have been highlighted in previous studies of smoking and nicotine dependence. Nominal associations with lung cancer were observed at both 8p11 (rs6474412[T], odds ratio (OR) = 1.09, P = 0.04) and 19q13 (rs4105144[C], OR = 1.12, P = 0.0006).

Contains fulltext : 88507.pdf (publisher's version ) (Closed access)

Tegenwoordig wordt er bij ecologisch en biologisch veldonderzoek al meer gebruik gemaakt van (non)invasieve onderzoeksmethoden variërend van bijvoorbeeld het vangen, merken, verdoven, inbrengen van een zender tot het afnemen van bloed bij dieren. De huidige artikel 12 opleidingen zijn gericht op handelingen aan dieren in biomedische experimenten. Echter de handelingen in veldbiologische experimenten zijn anders van aard en dat vereist specifieke kennis van de werknemer om het dierenwelzijn te waarborgen. Het hoofddoel van het project Artikel 12 Wildlife is het ontwikkelen van een curriculum ‘Artikel 12 Wildlife’ dat past binnen het huidige Bama stelsel. Dit om te voorzien in de vraag naar kundig personeel die dergelijke handelingen aan in het wild levende (proef)dieren kunnen en mogen verrichten.

Contains fulltext : 79889.pdf (publisher's version ) (Open Access), Phenylketonuria (PKU) is a classical example of an inherited metabolic disease, in which mental retardation can be prevented successfully by using a diet. However, in adult PKU new problems occur, such as vitamin deficiencies, osteoporosis and the maternal PKU syndrome. The aim of this review article is to provide guidelines for the clinician to understand and manage PKU in adults.

Contains fulltext : 81796.pdf (publisher's version ) (Closed access), OBJECTIVE: The objective was to investigate whether it is justified to discourage trials with less than 80% power. Trials with low power are unlikely to produce conclusive results, but their findings can be used by pooling then in a meta-analysis. However, such an analysis may be biased, because trials with low power are likely to have a nonsignificant result and are less likely to be published than trials with a statistically significant outcome. STUDY DESIGN AND SETTING: We simulated several series of studies with varying degrees of publication bias and then calculated the "real" one-sided type I error and the bias of meta-analyses with a "nominal" error rate (significance level) of 2.5%. RESULTS: In single trials, in which heterogeneity was set at zero, low, and high, the error rates were 2.3%, 4.7%, and 16.5%, respectively. In multiple trials with 80%-90% power and a publication rate of 90% when the results were nonsignificant, the error rates could be as high as 5.1%. When the power was 50% and the publication rate of non-significant results was 60%, the error rates did not exceed 5.3%, whereas the bias was at most 15% of the difference used in the power calculation. CONCLUSION: The impact of publication bias does not warrant the exclusion of trials with 50% power.

Contains fulltext : 81732.pdf (publisher's version ) (Open Access), BACKGROUND: Examination of the 2-dimensional probability distribution of thyroid-stimulating hormone (TSH) and free thyroxine (FT(4)) shows that the widths of the TSH and FT(4) reference intervals derived from this bivariate distribution are mutually interdependent, an aspect commonly ignored when interpreting thyroid testing results with separate reference intervals for TSH and FT(4). We desired to establish and critically evaluate a composite reference interval for TSH and FT(4) to allow bivariate classification of biochemical thyroid conditions. METHODS: FT(4) and TSH results of 871 healthy individuals [361 women and 510 men, 18-40 years old, without history of thyroid-related disease or medication, negative for anti-thyroid peroxidase (anti-TPO) antibody] were transformed to standard normal variables by logarithmic transformation with correction for skewness and subsequent normalization. We established a 95% reference interval of the distance of each FT(4)/TSH pair of values to the center of the 2-dimensional probability distribution. RESULTS: The bivariate 95% reference interval is enclosed by a circular profile with radius 2.45 SD. By contrast, conventional reference intervals comprise a square with the boundaries of -1.96 and +1.96 SD for both FT(4) and TSH that enclose only 90% of all data. Compared with the +/-1.96 SD square, the bivariate reference interval classified 4% fewer of 3651 healthy individuals older than 40 years as subclinically hyperthyroid and 14% fewer of 712 anti-TPO-positive healthy individuals as subclinically hypothyroid. CONCLUSIONS: Conventional application of separate cutoff values for FT(4) and TSH leads to overestimation of the incidence of subclinical thyroid disease. Application of a composite overall reference interval is recommended.

Contains fulltext : 80002.pdf (publisher's version ) (Closed access), BACKGROUND: Spina bifida is a class of neural tube defects, which are congenital malformations of the central nervous system with a prevalence of 0.5 to 12 per 1000 births globally. In this article we attempt to identify genes related to folate and its metabolic pathways that are involved in the etiology of spina bifida. METHODS: We selected 50 folate metabolism-related genes and genotyped polymorphisms in those genes. Eighty-seven polymorphisms in 45 genes passed quality controls. Associations with spina bifida were investigated in 180 patients and 190 controls. For those polymorphisms that were nominally associated with spina bifida risk, the relation with serum and red blood cell folate, vitamin B(12), and homocysteine was evaluated in controls. RESULTS: A polymorphism in CUBN was significantly associated with decreased spina bifida risk, after correction for multiple testing, and was related to increased vitamin B(12) (p = 0.039) and red blood cell folate (p = 0.001). The CUBN gene encodes the intrinsic factor-cobalamin receptor (or cubilin), a peripheral membrane protein that acts as a receptor for intrinsic factor-vitamin B(12) complexes. Vitamin B(12) is an important cofactor in the folate metabolism, and low B(12) status in mothers has been linked to neural tube defects in children. Other interesting findings include nominally significant associations with polymorphisms in TRDMT1, ALDH1L1, SARDH, and SLCA19A1 (RFC1). CONCLUSION: Our study indicates interesting new candidate genes and functional pathways for further study and confirms earlier findings. None of the genes CUBN, TRDMT1, ALDH1L1, or SARDH have been investigated previously for association with spina bifida.

Contains fulltext : 80084.pdf (publisher's version ) (Closed access), Psoriasis is a common inflammatory skin disease with a prevalence of 2-3% in individuals of European ancestry. In a genome-wide search for copy number variants (CNV) using a sample pooling approach, we have identified a deletion comprising LCE3B and LCE3C, members of the late cornified envelope (LCE) gene cluster. The absence of LCE3B and LCE3C (LCE3C_LCE3B-del) is significantly associated (P = 1.38E-08) with risk of psoriasis in 2,831 samples from Spain, The Netherlands, Italy and the United States, and in a family-based study (P = 5.4E-04). LCE3C_LCE3B-del is tagged by rs4112788 (r(2) = 0.93), which is also strongly associated with psoriasis (P < 6.6E-09). LCE3C_LCE3B-del shows epistatic effects with the HLA-Cw6 allele on the development of psoriasis in Dutch samples and multiplicative effects in the other samples. LCE expression can be induced in normal epidermis by skin barrier disruption and is strongly expressed in psoriatic lesions, suggesting that compromised skin barrier function has a role in psoriasis susceptibility.

Contains fulltext : 81259.pdf (publisher's version ) (Closed access), CONTEXT AND OBJECTIVE: The metabolic syndrome (MetS) indicates an increased cardiovascular risk. The objective of the present study was to determine the impact of the MetS and its individual traits on subclinical atherosclerosis, as measured with six noninvasive measurements of atherosclerosis (NIMA) in a 50- to 70-yr-old Dutch population-based cohort. Furthermore, we determined the impact of three different definitions of the MetS. DESIGN: We performed NIMA in 1517 participants of the Nijmegen Biomedical Study. The MetS was defined by definitions of the National Cholesterol Education Program, International Diabetes Federation, and the World Health Organization. RESULTS: Participants with the MetS (National Cholesterol Education Program) were characterized by increased subclinical atherosclerosis compared with participants without any trait of the MetS, as reflected by lower ankle-brachial index at rest [percent change (95% confidence interval), M: -5.2% (-9; -1), F: -3.1% (-6; -1)] and after exercise [M: -7.7% (-17;+2), F: -6.6% (-11; -2)], higher augmentation index [M: +4.8% (+3; +7), F: +1.9% (+4; +18)], increased pulse wave velocity [M: +22.8% (+15;+32), F: +20.5% (+14; +28)], increased intima-media thickness [M: +9.3% (+5; +13), F: +6.9% (+3; +11)], and thicker plaques [M: +17.6% (-2; +41), F: +26.6% (+5; +53)]. Most intriguingly, the number of traits was strongly associated with the severity of subclinical atherosclerosis because all NIMA gradually deteriorated with increasing number of traits present; NIMA were already deteriorated when one or two traits were present and further deteriorated when four or five traits of the MetS were present. Similar result were found when International Diabetes Federation and World Health Organization definitions of the MetS were used. CONCLUSIONS: For cardiovascular risk prediction, it is more important to take into account the presence of each individual trait and the number of traits of the MetS than to diagnose the presen

Contains fulltext : 80466.pdf (publisher's version ) (Open Access), BACKGROUND: Previous studies have extensively documented antimicrobial and chemotactic activities of beta-defensins. Human beta-defensin-2 (hBD-2) is strongly expressed in lesional psoriatic epidermis, and recently we have shown that high beta-defensin genomic copy number is associated with psoriasis susceptibility. It is not known, however, if biologically and pathophysiologically relevant concentrations of hBD-2 protein are present in vivo, which could support an antimicrobial and proinflammatory role of beta-defensins in lesional psoriatic epidermis. METHODOLOGY/PRINCIPAL FINDINGS: We found that systemic levels of hBD-2 showed a weak but significant correlation with beta defensin copy number in healthy controls but not in psoriasis patients with active disease. In psoriasis patients but not in atopic dermatitis patients, we found high systemic hBD-2 levels that strongly correlated with disease activity as assessed by the PASI score. Our findings suggest that systemic levels in psoriasis are largely determined by secretion from involved skin and not by genomic copy number. Modelling of the in vivo epidermal hBD-2 concentration based on the secretion rate in a reconstructed skin model for psoriatic epidermis provides evidence that epidermal hBD-2 levels in vivo are probably well above the concentrations required for in vitro antimicrobial and chemokine-like effects. CONCLUSIONS/SIGNIFICANCE: Serum hBD-2 appears to be a useful surrogate marker for disease activity in psoriasis. The discrepancy between hBD-2 levels in psoriasis and atopic dermatitis could explain the well known differences in infection rate between these two diseases.

Contains fulltext : 80860.pdf (publisher's version ) (Closed access), BACKGROUND: Previous reports showed inconsistent results about the potential role of flow-mediated dilatation (FMD) in cardiovascular(CV) risk prediction. Few data are available about the role of nitroglycerin-mediated dilatation (NMD), but recently, brachial artery diameter(BAD) appeared to have predictive value in CV risk prediction.We determined the relation of FMD, BAD and NMD with known CV risk factors and intima-media thickness (IMT), a well-established surrogate marker of atherosclerosis, in a community-based population, the Nijmegen Biomedical Study (NBS). MATERIALS AND METHODS: FMD, BAD and NMD were measured in the brachial, and IMT in the common carotid artery ultrasononically in 337 participants, aged 50-70 years. Traditional clinical and biochemical parameters were determined. RESULTS: Both FMD and NMD were not correlated with most CV risk factors or prevalent CVD. However, both IMT and BAD did show significant correlations with CV risk factors. In accordance, both IMT and BAD were significantly correlated with prevalent CVD (r=0.62 and r=-0.37, respectively) . Furthermore, FMD was not correlated with IMT and did hardly (R2=1.1%) improve the prediction of IMT by CV risk factors in regression analysis. However, both BAD and NMD did correlate with IMT (r=-0.29 and r=0.25, respectively). CONCLUSION: In our study, FMD and NMD were not related to known CV risk factors and prevalent CVD, and FMD was not correlated with IMT, a surrogate marker of atherosclerosis. Most intriguingly, BAD was significantly correlated with some CV risk factors, prevalent CVD and IMT. So, BAD is a potential valuable tool in CV risk prediction in middle-aged low-risk populations, whereas FMD is not.

Contains fulltext : 80199.pdf (publisher's version ) (Closed access), BACKGROUND: The aim of this study was to investigate whether inflammatory markers (interleukin-6 [IL-6] and C-reactive protein [CRP]) in the acute phase of deep vein thrombosis (DVT) are associated with elevated venous outflow resistance (VOR), thrombosis score (TS), reflux and the development of clinical post-thrombotic syndrome (PTS). METHODS: In 110 patients with a first DVT, plasma concentrations of IL-6 and CRP were determined on the day of admission. VOR, TS and reflux were measured 7 days, 1 and 3 months after diagnosis. After 1 year patients were evaluated for PTS using the Clinical, Etiologic, Anatomic and Pathophysiologic (CEAP) classification and Villalta scale. RESULTS: Median levels of IL-6 and CRP were 7 pg mL(-1) and 21 mg L(-1), respectively. After 3 months, VOR was elevated in 33 patients (30%), TS in 33 (30%) and reflux in 57 (52%). Incidence of PTS was 36.7% using CEAP>or=3 and 35.4% using Villalta-scale>or=5. Elevated levels of IL-6 and CRP were related to higher outcomes of VOR after 3 months [relative risks (RR) 2.4 (95% CI 1.5-3.9) and 1.4 (1.1-3.3), respectively] and for IL-6 to TS [1.5 (1.1-2.1)]. For reflux no relation was found. After 90 days, elevated outcomes of VOR, TS and reflux were related to PTS after 1 year. The association of IL-6 and CRP with PTS was weak using the CEAP classification with a RR of 1.2 (0.7-2.2) and 1.8 (0.9-3.3) and absent according to the Villalta scale 0.6 (0.2-1.4) and 1.2 (0.6-2.5), respectively. CONCLUSION: The results of this study suggest that inflammation might play a role in incomplete thrombus clearance, venous outflow obstruction and the development of PTS after 1 year.

Contains fulltext : 79709.pdf (publisher's version ) (Closed access), OBJECTIVE: The purpose of this randomized study was to evaluate the influence of immediate multilayer compression bandages before application of elastic stockings in the acute phase of deep-vein thrombosis (DVT) on development of the post-thrombotic syndrome (PTS). METHODS: Sixty-nine patients with acute symptomatic DVT were randomized to immediate bandaging (n = 34) or no bandaging (n = 35). After reduction of edema sized-to-fit elastic stockings were applied in all patients after 7-14 days. Follow-up visits and non-invasive examinations were planned after 7, 30 and 90 days and 1 year. Venous outflow resistance (VOR) was measured by strain gauge plethysmography. Thrombosis score (TS) and reflux were measured by duplex scanning. After one year patients were evaluated for clinical PTS using both the clinical scale of the CEAP classification and the Villalta score. RESULTS: Improvement of clinical symptoms and decrease of leg circumference was better on day 7 in the bandaging group, but after 1 and 3 months clinical symptoms had improved equally in both groups. In 7 patients in the no-bandaging group a bandage was applied after all because of persistent edema after 10 days. There were no differences in VOR, TS and reflux. Using the CEAP classification the incidence of PTS was 39% in patients with bandages and 42% in patients without bandages (RR 0.91, 95% CI 0.50-1.66). Using the Villalta score the incidence of PTS was resp. 29 and 33% (RR 0.87, 95% CI 0.41-1.8). There was no difference in severity of PTS. CONCLUSION: Immediate multilayer compression bandaging in the acute phase of DVT is effective in reducing edema and complaints in the first week, but has no effect on thrombus regression, valve incompetence and the development of clinical PTS after 1 year.

RU Radboud Universiteit Nijmegen, 30 september 2009, Promotores : Kiemeney, L.A.L.M., Hermus, A.R.M.M. Co-promotores : Heijer, M. den, Blom, H.J., Contains fulltext : 80617.pdf (publisher's version ) (Open Access), Homocysteine is a sulphur-containing intermediate in one-carbon metabolism. Plasma total homocysteine (tHcy) concentration is associated to common diseases including venous thrombosis and neural tube defects (NTD). Identification of genetic determinants of plasma tHcy concentration can contribute to clarification of the underlying pathogenic processes. In the last 13 years, a focus on single locus association studies of functional variants has resulted in establishment of the MTHFR677C>T polymorphism as a genetic determinant of plasma tHcy concentrations. In this thesis, we looked beyond the single locus effects of evident candidate DNA variants and beyond the traditional genetic epidemiological study designs. The first part of the thesis describes a linkage study for plasma tHcy and four candidate-gene association studies for plasma tHcy, related metabolites, recurrent venous thrombosis (RVT), and NTD. The genome wide-linkage analysis revealed three regions that might harbour genetic determinants for plasma tHcy. Extensive association studies for over 40 one-carbon metabolism-related genes led to identification of novel candidates and known DNA variants that each had small contributions in plasma tHcy variation (<<2%); these studies also underlined the relative importance of MTHFR677C>T and CBS variants. Using multi-locus analysis we found a strongly associated five-locus interacting genotype that explained 17% of plasma tHcy variation in our population. Simultaneous analysis of candidate genes for plasma tHcy and folate and methionine concentrations indicated heterogeneity in genetic determinants for the three metabolites. The UCP2 45bp del was found to influence recurrent venous thrombosis risk and variants in CUBN and TRDMT1 were associated with NTD but not via plasma tHcy concentration. In the second part of the thesis, a new hybrid design is proposed which is shown to allow a powerful and flexible identification of both maternal and offspring genetic effects c

Contains fulltext : 80479.pdf (publisher's version ) (Closed access), The hepatic peptide hormone hepcidin plays a central role in body iron metabolism. Despite its promise as a biomarker, the availability of high-sensitive hepcidin assays is still limited. We developed and validated a RadioImmunoAssay (RIA) to measure hepcidin quantitatively in human serum. This assay exhibited a very low detection limit (0.02 microg/l), low imprecision (coefficient of variation-range 4.4-6.2%) and good linearity and recovery (range: 81-105%). Hepcidin levels of samples of controls and patients with iron deficiency and inflammation showed an excellent correlation with our previously described quantitative time-of-flight mass spectrometry assay (range 2.5-266.8 microg/l, r = 0.92, P < 0.0001). The RIA detected: (i) differences in mean hepcidin levels between men (n = 29) and women (n = 35), (ii) differences between individuals of different HFE-genotypes (n = 60) and (iii) daily increases in hepcidin levels (n = 64). The assay (i) is easy to perform and many samples can be processed within one assay-run, (ii) shows accurate, reproducible and high-sensitive measurements and (iii) is anticipated to be particularly useful to study the effects of pathological and physiological stimuli on hepcidin levels in the lower range.

Contains fulltext : 81561.pdf (publisher's version ) (Closed access), Kidney stone disease is a common condition. To search for sequence variants conferring risk of kidney stones, we conducted a genome-wide association study in 3,773 cases and 42,510 controls from Iceland and The Netherlands. We discovered common, synonymous variants in the CLDN14 gene that associate with kidney stones (OR = 1.25 and P = 4.0 x 10(-12) for rs219780[C]). Approximately 62% of the general population is homozygous for rs219780[C] and is estimated to have 1.64 times greater risk of developing the disease compared to noncarriers. The CLDN14 gene is expressed in the kidney and regulates paracellular permeability at epithelial tight junctions. The same variants were also found to associate with reduced bone mineral density at the hip (P = 0.00039) and spine (P = 0.0077).

In maart 2009 is het KIGO project Artikel 12 Wildlife van start gegaan. Dit project is onderdeel van het GKC programma ‘Welzijn van dieren’. Aanleiding voor dit project is dat in toenemende mate bij ecologisch en biologisch veldonderzoek gebruik gemaakt van wordt van (non)invasieve onderzoeksmethoden variërend van bijvoorbeeld het vangen, merken, verdoven, inbrengen van een zender tot het afnemen van bloed. Hierbij is mogelijk sprake van enig ongerief voor de dieren. Formeel vallen een aantal van deze handelingen onder de Wet op de Dierproeven (Wod) en moet degene die deze handelingen verricht bevoegd zijn voor het uitvoeren daarvan (artikel 9 of 12 status ex Wod). Op dit moment zijn er in de Wod nog geen aparte bepalingen voor werkenden in de veldbiologische sector opgenomen. Er is echter sprake van toenemende maatschappelijke belangstelling voor een maatschappelijk verantwoorde ethische behandeling van dieren.

Contains fulltext : 71309.pdf (publisher's version ) (Closed access), Psoriasis is a common inflammatory skin disease with a strong genetic component. We analyzed the genomic copy number polymorphism of the beta-defensin region on human chromosome 8 in 179 Dutch individuals with psoriasis and 272 controls and in 319 German individuals with psoriasis and 305 controls. Comparisons in both cohorts showed a significant association between higher genomic copy number for beta-defensin genes and risk of psoriasis.

Contains fulltext : 69271.pdf (publisher's version ) (Closed access), BACKGROUND: Plasma methylmalonic acid (MMA) is a specific marker for functional cobalamin deficiency. This deficiency can give rise to non-specific but serious symptoms in childhood such as developmental delay, convulsions and failure to thrive and may even lead to irreversible neurological damage. AIM OF THE STUDY: To analyse plasma MMA concentrations in Dutch children and to evaluate possible factors influencing its concentration. METHODS: A number of 186 Dutch children aged 0-19 years were analysed cross-sectionally. Blood was collected to measure MMA, total homocysteine (tHcy), cobalamin (Cbl) and serum creatinine concentrations. In addition, information about medical history, age and sex was recorded. RESULTS: The geometric mean (GM) plasma MMA concentration was 0.17 micromol/l (95% CI 0.07-0.42) and the GM tHcy was 6.6 micromol/l (95% CI 3.1-13.9). There is a slight positive correlation between plasma MMA and age in children >1 year (r = 0.211, P < 0.05). Plasma MMA concentrations were significantly higher in children with low Cbl concentrations. No significant difference in MMA, Cbl, tHcy or creatinine concentrations between sexes could be observed. Regression analysis showed that Cbl was the strongest determinant of plasma MMA (regression coefficient -0.414, P < 0.05). The association between MMA and Cbl is stronger at increasing age (P for trend 0.045). CONCLUSIONS: Plasma Cbl is the main determinant of MMA in this group of Dutch children. The strength of the association increased with increasing age.

Contains fulltext : 69311.pdf (publisher's version ) (Closed access), OBJECTIVE: Analysis of the value of intraoperative parathormone (PTH) measurement in patients with primary hyperparathyroidism. DESIGN: Prospective study. METHOD: Evaluation of the value of intraoperative measurement ofPTH in 75 patients (including 19 patients with multiple endocrine neoplasia(MEN)-1 syndrome) who underwent parathyroidectomy in 2001-2005. RESULTS: The so-called Miami-criterion (PTH concentration 10 min after excision at least 50% below the value measured prior to the first incision) correctly predicted the success of the operation in 91% of the subjects. The success rate was correctly predicted as follows: in subgroups of patients with MEN-1 syndrome, 85%, patients after exclusion of MEN-1, 94%, and patients in whom a solitary adenoma was likely after preoperative localization studies, 97%. In 13% of the total number of operations, PTH-measurements led to further exploration, removal of additional parathyroid tissue and normocalcemia postoperatively. In patients without MEN-1 syndrome, in whom a solitary adenoma was likely on the basis of preoperative investigations, it was possible to limit the operation to a unilateral procedure in 87%. CONCLUSION: In the majority of patients with primary hyperparathyroidism, intraoperative PTH-measurement in combination with preoperative imaging studies leads to patients being cured with a unilateral instead of a bilateral operation.

RU Radboud Universiteit Nijmegen, 10 januari 2008, Promotor : Wevers, R.A. Co-promotores : Blom, H.J., Heijer, M. den, Contains fulltext : 71350.pdf (Publisher’s version ) (Open Access)

Contains fulltext : 71438.pdf (publisher's version ) (Closed access), OBJECTIVES: H19 is an imprinted gene coding for an oncofetal RNA that is down-regulated postnatally. Reactivation of the H19 gene has been observed in bladder tumors, and H19 expression has been associated with early recurrence of disease. In this study we examined whether sequence variants within the H19 gene are associated with the risk of developing bladder cancer. METHODS: Five tagging single nucleotide polymorphisms (tagSNPs) covering the H19 gene and its promoter region were selected with the use of Haploview software. One hundred and seventy-seven bladder cancer patients who were referred to our university hospital were genotyped for these tagSNPs. The genotypes were compared with those of a random sample of 204 controls of the general population. RESULTS: A significantly decreased risk of bladder cancer was found for the rs2839698 TC genotype (odds ratio [OR], 0.60; 95% confidence interval (95%CI), 0.36-0.99), but not for CC homozygotes. The rs2839698 TC genotype was especially associated with a reduced risk of developing non-muscle-invasive disease (OR, 0.52; 95%CI, 0.28-0.94). Borderline significantly decreased risks of bladder cancer were found for the rs2107425 CT genotype (OR, 0.66; 95%CI, 0.43-1.00), but not for TT homozygotes or for T allele carriers of rs217727 (OR, 0.74; 95%CI, 0.51-1.06). Haplotype analysis did not result in stronger associations with bladder cancer compared with the single-locus analyses. CONCLUSIONS: An SNP polymorphism in the non-protein-encoding H19 gene is associated with a decreased risk of developing non-muscle-invasive bladder cancer. This association was found for only heterozygotes, not for homozygotes.

Contains fulltext : 69593.pdf (publisher's version ) (Closed access)

Contains fulltext : 70671.pdf (publisher's version ) (Closed access), BACKGROUND: Endothelial nitric oxide synthase (eNOS) produces nitric oxide, which plays a role in vasodilatation and in the regulation of cell growth and apoptosis. eNOS-deficient mice have impaired cardiac development resulting in congenital heart defects (CHDs). In humans, a single nucleotide polymorphism in the gene coding for eNOS (894G>T) is associated with birth defects. METHODS: We investigated the eNOS 894G>T polymorphism in relation to CHDs using a case-control study and a case-parent study. Possible interaction with maternal cigarette smoking during pregnancy and periconceptional folic acid supplementation was also investigated in a case-only approach. RESULTS: The eNOS 894G>T polymorphism was genotyped in 170 CHD-affected children, in 161 of their mothers, 215 control children and 240 control women. For the case-parent study, 135 complete triads were available. The sum of eNOS 894 GT and TT vs. GG genotypes in children was associated with increased CHD risk [odds ratio, OR 1.5 (95% CI 1.03-2.31)]. There was no preferential transmission of the 894T allele [OR 1.2 (95% CI 0.81-1.69)]. Overall, the maternal eNOS 894 GT or TT vs. GG genotypes were not associated with increased CHD risk. The maternal 894TT genotype in combination with maternal smoking was associated with an increased risk, particularly for a subgroup of other than conotruncal heart defects [OR 3.3 (95% CI 1.00-11.1)]. No interaction with periconceptional folic acid supplementation was observed. CONCLUSIONS: Our data indicate that the eNOS 894G>T polymorphism is associated with increased CHD risk. The study also provides evidence of a possible gene-environment interaction effect on CHD risk between the maternal eNOS 894G>T variant and maternal cigarette smoking during pregnancy. This observation should be interpreted with caution because of the relatively small subgroups. Further study in a larger group of CHD subjects is required.

Contains fulltext : 69561tits.pdf (publisher's version ) (Closed access), Adiponectin is secreted from adipocytes in different multimers, of which the high molecular weight (HMW) form is supposed to mediate favorable metabolic and anti-atherogenic effects. We determined adiponectin multimers in 29 female and 22 male patients with familial combined hyperlipidemia (FCH) and 51 age-, gender-, and BMI-matched controls in relation to cardiovascular disease (CVD). We observed a clear sexual dimorphism of total adiponectin and its multimers. Female, but not male, FCH patients had significant lower total adiponectin and both HMW and low molecular weight (LMW) adiponectin than controls. The adiponectin sensitivity index (ASI), reflected by HMW/total adiponectin, and the LMW/HMW adiponectin ratio did not differ significantly between FCH females and control females. However, FCH females with CVD exhibited significantly lower ASI (34.2+/-10.1% vs 46.0+/-7.1%) and higher LMW/HMW ratio (1.5+/-0.8 vs 0.7+/-0.3) compared to FCH females without CVD, reflecting a more atherogenic adiponectin multimer distribution.

Contains fulltext : 69151.pdf (publisher's version ) (Closed access), Adult human height is one of the classical complex human traits. We searched for sequence variants that affect height by scanning the genomes of 25,174 Icelanders, 2,876 Dutch, 1,770 European Americans and 1,148 African Americans. We then combined these results with previously published results from the Diabetes Genetics Initiative on 3,024 Scandinavians and tested a selected subset of SNPs in 5,517 Danes. We identified 27 regions of the genome with one or more sequence variants showing significant association with height. The estimated effects per allele of these variants ranged between 0.3 and 0.6 cm and, taken together, they explain around 3.7% of the population variation in height. The genes neighboring the identified loci cluster in biological processes related to skeletal development and mitosis. Association to three previously reported loci are replicated in our analyses, and the strongest association was with SNPs in the ZBTB38 gene.

Contains fulltext : 69270.pdf (publisher's version ) (Open Access), Several conditions apparent at birth, e.g., neural tube defects (NTDs) and cardiac anomalies, are associated with polymorphisms in folate-related genes, such as the 677C --> T polymorphism of the methylenetetrahydrofolate reductase (MTHFR) gene. Similar associations have been established for several constitutional chronic diseases in adulthood, such as schizophrenia, cardiovascular diseases, dementia, and even neoplasias in different organ systems. This spectrum of developmental anomalies and constitutional diseases may be linked to high-risk conceptions related to preovulatory overripeness ovopathy (PrOO). Some developmental anomalies, such as NTDs, are to a large extent prevented by supplementation of folic acid before conception, but supplementation does not seem to prevent cardiovascular disease or cognitive decline. These diverging results can be elucidated by introduction of the PrOO concept, as MTHFR polymorphisms and inherent low folate levels induce both non-optimal maturation of the oocyte and unsuccessful DNA methylation and demethylation, i.e. epigenetic mutations. The PrOO concept is testable and predicts in a random population the following: (1) female carriers of specific genetic MTHFR variants exhibit more ovulatory disturbances and inherent subfecundity traits, (2) descendents from a carrier mother, when compared with those from a wild-type mother, are more frequently conceived in PrOO high-risk conditions and, thus, (3) disadvantaged in life expectancy. If so, some MTHFR polymorphisms represent a novel, genetically determined, PrOO high-risk conception category comparable to those which are environmentally and behaviorly influenced. These high-risk conditions may cause developmental anomalies and defective epigenetic reprogramming in progeny. The interaction between genetic and environmental factors is a plausible mechanism of multifactorial inheritance.

Contains fulltext : 70006.pdf (publisher's version ) (Closed access), BACKGROUND: Overt and subclinical hyperthyroidism are both well-known independent risk factors for atrial fibrillation. We aimed to investigate the association of high-normal thyroid function with the development of atrial fibrillation in a prospective population-based study in the elderly. METHODS: The association between thyroid-stimulating hormone (TSH) levels and atrial fibrillation was examined in 1426 subjects with TSH levels in the normal range (0.4-4.0 mU/L) and without atrial fibrillation at baseline. In 1177 of the 1426 persons in this group, we also examined the association between free thyroxine levels within the normal range (0.86-1.94 ng/dL [to convert to picomoles per liter, multiply by 12.871]) and atrial fibrillation. During a median follow-up of 8 years, 105 new cases of atrial fibrillation were identified. Hazard ratios (HRs) were calculated with 95% confidence intervals (CIs) using Cox proportional hazards models after adjustment for age, sex, current smoking, former smoking, body mass index, systolic blood pressure, hypertension, history of myocardial infarction, presence of heart failure, left ventricular hypertrophy on the electrocardiogram, diabetes mellitus, total cholesterol level, and time of the drawing of blood samples. RESULTS: The risk of atrial fibrillation was associated with the TSH level. The multivariate adjusted HR was 1.94 (95% CI, 1.13-3.34, lowest vs highest quartile; P for trend, .02). The multivariate adjusted level of free thyroxine showed a graded association with risk of atrial fibrillation (HR, 1.62; 95% CI, 0.84-3.14, highest vs lowest quartile; P for trend, .06). CONCLUSION: Within the normal range of thyroid parameters, persons with high-normal thyroid function are at an increased risk of atrial fibrillation.

Contains fulltext : 70547.pdf (publisher's version ) (Closed access), A persistent increase in incidence of thyroid carcinoma (TC) has been reported worldwide. The aim of our study was to assess trends in incidence and mortality of TC in The Netherlands between 1989 and 2003 and to examine whether these trends correlate with changes in diagnostic practices such as changes in the number of fine needle aspiration biopsies (FNAB) and/or thyroid surgeries. Population-based incidence and mortality data were retrieved from the Netherlands Cancer Registry. Data concerning FNAB and thyroid surgeries were obtained through the nationwide network and registry of histo- and cytopathology in The Netherlands (PALGA). Overall, the incidence of TC remained unchanged. However, there was a slight increase in incidence of papillary TC of 2.1% per year (p < 0.001) particularly in stage I tumors, possibly, in part, because of a marked increase in use of FNAB. Appropriate iodine intake, reduced radiation exposure and a more conservative diagnostic approach toward asymptomatic thyroid nodules may explain why this increase is less pronounced compared to other countries. Incidence of other subtypes of TC decreased (follicular TC, 1.3% per year, p = 0.02 and anaplastic TC, 7.1% per year, p = 0.006) or remained unchanged (medullary TC). The number of FNABs per year progressively increased from 1,093 in 1989 to 4,123 in 2003, whereas the number of thyroid surgeries decreased from 3,419 in 1989 to 2,825 in 2003. The mortality rates decreased by 2.3% per year (p = 0.01). The decrease in incidence of both follicular and anaplastic TC is assumed to be largely responsible for the decrease in TC mortality rates.

Contains fulltext : 71130.pdf (publisher's version ) (Closed access), BACKGROUND: Hyperhomocysteinemia has been associated with an increased risk of venous thrombosis, which might be mediated through an oxidative stress dependent mechanism. The function of uncoupling protein-2 (UCP2) is still under debate, but it has been suggested to play a role in reduction of mitochondrial reactive oxygen species. In the present study, we investigated whether the 45 bp deletion/insertion (del/ ins) polymorphism in the UCP2 gene is associated with elevated homocysteine levels and whether it might be associated with an increased risk of recurrent venous thrombosis (RVT). METHODS: The 45 bp del/ins polymorphism in the UCP2 gene was genotyped by PCR analysis in 161 RVT cases and 386 controls of Caucasian origin in which fasting- and post-load homocysteine levels were previously determined. Statistical analysis was performed to assess whether the UCP2 45 bp del/ins polymorphism was associated with plasma total homocysteine levels and venous thrombosis risk. RESULTS: Post-load homocysteine levels were positively associated with UCP2 45 bp ins/ins genotype (P = 0.02). None of the UCP2 45 bp ins/del genotypes were associated with fasting plasma homocysteine levels. The frequency of the UCP2 45 bp ins/ins genotype was 12.4% in RVT cases compared to 8.3% in controls, which resulted in an odds ratio of 1.8 (95% CI 1.0-3.4). CONCLUSIONS: The results of our study show that the common 45 bp del/ins polymorphism in the UCP2 gene is associated with hyperhomocysteinemia, which might increase the risk of venous thrombosis. However, the mechanism is not fully understood and additional studies should be performed to confirm our findings.

Contains fulltext : 69712.pdf (publisher's version ) (Closed access), BACKGROUND: An impaired DNA methylation has been suggested to underlie the complex etiology of neural tube defects (NTDs). Previously, we have demonstrated that inhibition of methylation by periodate oxidized adenosine (Adox) results in a widening of the anterior neuropore (ANP) in our in vitro chick embryo model. Since DNA methylation is the chief regulator of gene expression, we hypothesize that inhibition of methylation by Adox in our in vitro chick embryo model will affect the expression of genes that may be involved in neurulation. In the present study, we therefore examined differential gene expression between Adox-treated and control chick embryos, using the Affymetrix Genechip Chicken Genome Array. METHODS: Chick embryos of 4/5 somites were cultured in vitro with saline (control) or Adox and cranial parts were excised. Gene expression profiling was determined using the Affymetrix Genechip Chicken Genome Array on RNA isolated from two pools of Adox-treated cranial parts (n = 12) and two pools of saline-treated cranial parts (n = 12). Microarray data were validated by QPCR analysis. RESULTS: In the Adox-treated chick embryos, 45 probesets were up-regulated (fold > or = 2.0, p < 0.05) and 32 probesets were down-regulated (fold < or = 0.5, p < 0.05). Of the 15 genes selected for QPCR analysis, the up-regulation of phosphoserine phosphatase (PSPH), unc-51-like kinase 1 (ULK1), and chemokine (C-X-C motif) ligand 12/stromal cell-derived factor 1 (CXCL12/SDF-1) was confirmed. CONCLUSIONS: Inhibition of methylation by Adox affects gene expression in our in vitro chick embryo model. Further research will focus on the gene-specific methylation patterns of PSPH, ULK1, and CXCL12/SDF-1 and the role of the products of these genes in neurulation.

Contains fulltext : 71436.pdf (publisher's version ) (Closed access), BACKGROUND: Evidence is emerging for the association of aberrant homocysteine-methylation cycle and increased risk of schizophrenia. METHODS: We examined the prevalence of the catechol-O-methyltransferase (COMT) 324G>A (Val108/158Met) and methylenetetrahydrofolate reductase (MTHFR) 677C>T polymorphisms in 252 patients with schizophrenia and 405 control subjects. All subjects were of Dutch ancestry. RESULTS: The COMT 324AA genotype was not associated with an increased risk of schizophrenia (odds ratio (OR)=1.38 [95% CI: 0.88-2.16], P=0.162), and the MTHFR 677TT genotype showed a nearly significant increased risk for schizophrenia (OR=1.65 [95% CI: 0.97-2.82], P=0.067). The odds ratio for schizophrenia associated with joint occurrence of the COMT 324AA and MTHFR 677TT genotype was 3.08 (95% CI: 1.08-8.76) (P=0.035). Increasing number of low enzyme activity alleles in the COMT and MTHFR genotype combinations were associated with an increased risk of schizophrenia (test for trend, P=0.017). CONCLUSIONS: Our findings do not support a major role for the COMT 324AA and MTHFR 677TT genotype alone, but the combination of both genotypes might increase schizophrenia susceptibility.

RU Radboud Universiteit Nijmegen, 11 januari 2007, Promotor : Hermus, A.R.M.M. Co-promotores : Heijer, M. den, Blom, H.J., Item does not contain fulltext, Homocysteine is a intermediary product of protein metabolism. A high concentration of homocysteine in the blood is associated with a higher risk of cardiovascular disease, including venous thrombosis. Homocysteine levels are in part determined by genetic factors and vitamin intake (such as vitamin B12). The main goal of the presented research was to identify genetic factors (polymorphisms) that affect homocysteine levels and to assess if these polymorphisms also increased the risk of recurrent venous thrombosis. In addition, we evaluated vitamin B12 as a risk factor of recurrent venous thrombosis. We investigated a polymorphism in the catechol-O-methyltransferase gene, which is involved in so-called 'transmethylation reactions', in relation to homocysteine levels. Individuals carrying this polymorphism had higher homocysteine levels than subjects that did not carry this variant. In addition, this polymorphism was more common in recurrent venous thrombosis cases than the general population. This supports the hypothesis that high homocysteine reflects a disturbed transmethylation, which increases venous thrombosis risk. We also developed a method to study metabolites in the blood that report on the ability of our body to perform transmethylation reactions. It appeared that the way the blood samples were stabilized was of great importance for the reliability of our method. Future studies will have to point out whether a disturbed transmethylation is involved in the aetiology of venous thrombosis. Finally, we show that a low vitamin B12 status, which is a cause of high homocysteine levels, is associated with an increased risk of recurrent venous thrombosis. Measuring methylmalonic acid, a marker of intracellular vitamin B12 availability, seems more suitable for measuring vitamin B12 status than plasma vitamin B12 itself.

Contains fulltext : 52671.pdf (publisher's version ) (Closed access), OBJECTIVE: Durable blockade of tumour necrosis factor-alpha (TNF-alpha) in patients with rheumatoid arthritis (RA) suppresses disease activity and its progression. Cardiovascular diseases are 1.5-2-fold more frequent in RA patients than in the general population. Although TNF-alpha has well-established effects on lipid metabolism, the long-term effects of TNF-alpha blockade on lipid pattern are still unclear. In the present study, we investigated the effects of 1-year therapy with anti-TNF on the lipid profile of RA patients. METHODS: Disease activity (DAS28) and plasma lipoproteins concentrations (total, HDL and LDL-cholesterol, triglycerides, ApoA, ApoB) were assessed in 55 RA patients and 55 controls. The whole RA group was followed up for 6 months, and 31 of the patients were followed up for 1 year. RESULTS: In RA patients, DAS28 decreased after 2 weeks from the start of therapy (p<0.001) and remained low during the entire study duration. Short-term effects of anti-TNF on plasma lipid concentrations seemed beneficial and anti-atherogenic. However, these changes did not persist: plasma concentrations of total and LDL-cholesterol and the atherogenic index increased after 6 months and 1 year from the start of therapy. During therapy, the changes in disease activity and inflammatory status were inversely correlated with changes in plasma total and HDL cholesterol levels and positively correlated with the variation of atherogenic index. CONCLUSION: We conclude that one-year therapy with infliximab is likely to lead to a more pro-atherogenic pattern of the plasma lipids concentrations. However, the overall impact of these changes on the cardiovascular risk is more complex, considering the strong anti-inflammatory effects of anti-TNF drugs.

Item does not contain fulltext, BACKGROUND: Folate is important in purine and thymidylate synthesis and, via homocysteine remethylation, facilitates S-adenosylmethionine-dependent transmethylation. Low folate availability leads to hyperhomocysteinemia, which is a risk factor for arterial vascular disease and venous thrombosis. Genetic variation in folate-metabolizing genes may affect folate availability and hence confer a greater risk of venous thrombosis. METHODS: We genotyped the thymidylate synthase (TYMS) 28-bp repeat and 6-bp deletion, and the reduced folate carrier (RFC1) 80G>A and AICAR transformylase/inosine monophosphate (IMP) cyclohydrolase (ATIC) 346C>G polymorphisms in population-based controls (n=431), and assessed their effect on plasma total homocysteine (tHcy), and serum and red blood cell (RBC) folate. We investigated the associations between these variants and disease risk in a retrospective case-control study on recurrent venous thrombosis (n=173) as well. RESULTS: None of the genotypes, alone or in combination, were associated with major changes in tHcy. However, the TYMS 28-bp repeat was associated with serum and RBC folate levels. We found no evidence that the genetic variants studied were associated with recurrent venous thrombosis risk. CONCLUSIONS: The TYMS 28-bp repeat and 6-bp deletion, and RFC1 80G>A and ATIC 346C>G polymorphisms are not associated with tHcy, but we did observe an association between the TYMS 28-bp repeat and serum and RBC folate in a general population. None of the polymorphisms was associated with recurrent venous thrombosis risk.

Contains fulltext : 53566.pdf (publisher's version ) (Closed access), We analysed the diversity of tenascin-X (TNX) species in serum and studied parameters that could affect determination of TNX levels in serum. Using western blot analysis we identified at least seven distinct TNX species, ranging from 75 kDa to the presumably full-length 450 kDa form. Purification of serum TNX followed by sequence analysis positively identified two major TNX species of 75 and 140 kDa. We found that serum TNX binds to tropoelastin but not to fibrillar collagens. We conclude that serum TNX is composed of distinct molecular species that retain functional activity.

Contains fulltext : 53092.pdf (publisher's version ) (Open Access), A disturbed methylation has been proposed as a mechanism via which homocysteine is associated with diseases like vascular disease, neural tube defects and mental disorders. Catechol-O-methyltransferase (COMT) is involved in the S-adenosylmethionine-dependent methylation of catecholamines and catecholestrogens and in this way contributes to homocysteine synthesis. COMT dysfunction has been related to schizophrenia and breast cancer. We hypothesized that COMT dysfunction by virtue of functional genetic polymorphisms may affect plasma total homocysteine (tHcy). Our primary objective was to study the association between common COMT polymorphisms and tHcy. Secondly, we evaluated these polymorphisms as a risk factor for recurrent venous thrombosis. We obtained genotype data from four polymorphisms in the COMT gene (rs2097603, rs4633, rs4680 [324G>A] and rs174699) from 401 population-based controls. We performed haplotype analysis to investigate the association between common haplotypes and tHcy. In addition, we assessed the rs4680 variant as a genetic risk factor in a case-control study on recurrent venous thrombosis (n = 169). We identified a common haplotype that was significantly associated with tHcy levels. This effect was largely explained by the rs4680 variant, resulting in an increase in tHcy of 10.4% (95% CI 0.01 to 0.21, p = 0.03) for 324AA compared with 324GG subjects. Interestingly, we found that the 324AA genotype was more common in venous thrombosis patients (OR 1.61 [95% CI 0.97 to 2.65], p = 0.06) compared to control subjects. We show that the COMT rs4680 variant modulates tHcy, and might be associated with venous thrombosis risk as well.

Contains fulltext : 53572.pdf (publisher's version ) (Closed access), Homocysteine may have a thrombogenic effect through inhibition of inactivation of factor Va by activated protein C. Because factor V Leiden also leads to resistance of factor V to activated protein C, it would be possible that both factors show interaction for the risk of venous thrombosis. This has been reported in some studies, but not in others. We performed a metaanalysis to investigate a possible interaction between factor V Leiden and hyperhomocysteinemia, including 825 subjects with venous thrombosis and 2,109 controls, for the risk of venous thrombosis. In addition, we assessed a possible interaction between factor V Leiden and MTHFR 677TT genotype (the most common genetic determinant of homocysteine levels), including 2,547 subjects with venous thrombosis and 4,327 controls. We also investigated the interaction effect of factor V Leiden and hyperhomocysteinemia in a large case-only study using data of the VITRO study, including 2,077 subjects with first-time venous thrombosis. The meta-analysis yielded no evidence for additive or multiplicative interaction between factor V Leiden and hyperhomocysteinemia [relative excess risk due to interaction (RERI) -1.77 (95%CI -8.61 to 5.08) and multiplicative interaction term 0.86 (95%CI 0.35 to 2.14)]. The case-only study also showed no interaction effect [0.58 (95%CI 0.29 to 1.16)]. Also the metaanalysis on factor V Leiden and MTHFR 677TT yielded no evidence of interaction; RERI 0.13 (95%CI -3.60 to 3.86) and multiplicative interaction term 1.23 (95%CI 0.72 to 2.11). Both the meta-analyses of published studies and a large case-only study did not show evidence for interaction between factor V Leiden and hyperhomocysteinemia for risk of venous thrombosis.

RU Radboud Universiteit Nijmegen, 29 maart 2007, Promotor : Hermus, A.R.M.M. Co-promotores : Heijer, M. den, Blom, H.J., Borm, G.F., Contains fulltext : 51620.pdf (Publisher’s version ) (Open Access)

Contains fulltext : 53106.pdf (publisher's version ) (Closed access), BACKGROUND: Hyperhomocysteinemia has been associated with vascular disease in many epidemiologic studies, but only a few have reported on the relation between hyperhomocysteinemia and aneurysms of the abdominal aorta (AAAs). Although these studies showed higher homocysteine concentrations in patients with AAA than in controls, little attention had been given to possible confounding factors. Most patients with AAA are of older age, have an impaired renal function, and have other risk factors for cardiovascular disease. This matched case-control study investigated the relation between homocysteine concentration (before and after methionine loading) and AAA, taking into account possible confounders such as age, sex, and concentrations of creatinine and B vitamins. METHODS: Patients with a history of AAA were recruited from the outpatient clinic; 60% had already undergone surgery for their AAA. They were asked to invite a friend or neighbor to participate as a control subject (age-matched and sex-matched). Concentrations of homocysteine, vitamin B6, vitamin B12, folate, and creatinine were determined in the fasting state, and blood was taken for methylenetetrahydrofolate reductase (MTHFR) mutation analysis. Six hours after oral methionine loading, the postmethionine load homocysteine concentration was determined. RESULTS: Univariate analysis showed an odds ratio (OR) of 2.2 (95% confidence interval (CI), 0.9 to 5.5) for the risk of AAA for the highest quartile of homocysteine concentration. After adjustment for creatinine, the OR was markedly reduced to 1.24 (95% CI, 0.42 to 3.66), and this risk further attenuated in the multivariate analysis. Univariate analysis of the B vitamins showed an increased risk of AAA for the bottom quartile of vitamin B6 (OR, 3.75; 95% CI, 1.22 to 11.54), which even increased after adjustments. The relative risk associated with the MTHFR 677TT polymorphism was 2.1 (95% CI, 0.9 to 5.3). CONCLUSION: Vitamin B6, but not homocysteine, is an inde

Contains fulltext : 53203.pdf (publisher's version ) (Closed access), To identify interacting loci in genetic epidemiological studies the application of multi-locus methods of analysis is warranted. Several more advanced classification methods have been developed in the past years, including multiple logistic regression, sum statistics, logic regression, and the multifactor dimensionality reduction method. The objective of our study was to apply these four multi-locus methods to simulated case-control datasets that included a variety of underlying statistical two-locus interaction models, in order to compare the methods and evaluate their strengths and weaknesses. The results showed that the ability to identify the interacting loci was generally good for the sum statistic method, the logic regression and MDR. The performance of the logistic regression was more dependent on the underlying model and multiple comparison adjustment procedure. However, identification of the interacting loci in a model with two two-locus interactions of common disease alleles with relatively small effects was impaired in all methods. Several practical and methodological issues that can be considered in the application of these methods, and that may warrant further research, are identified and discussed.

Contains fulltext : 53690.pdf (publisher's version ) (Closed access), The Nijmegen Biomedical Study is a population-based cross-sectional study conducted in the eastern part of the Netherlands. As part of the overall study, we provide reference values of estimated glomerular filtration rate (GFR) for this Caucasian population without expressed risk. Age-stratified, randomly selected inhabitants received a postal questionnaire on lifestyle and medical history. In a large subset of the responders, serum creatinine was measured. The GFR was then measured using the abbreviated Modification of Diet in Renal Disease (MDRD) formula. To limit possible bias, serum creatinine was calibrated against measurements performed in the original MDRD laboratory. The study cohort included 2823 male and 3274 female Caucasian persons aged 18-90 years. A reference population of apparently healthy subjects was selected by excluding persons with known hypertension, diabetes, cardiovascular- or renal diseases. This healthy study cohort included 1660 male subjects and 2072 female subjects, of which 869 of both genders were 65 years or older. The median GFR was 85 ml/min/1.73 m(2) in 30-to 34-year-old men and 83 ml/min/1.73 m(2) in similar aged women. In these healthy persons, GFR declined approximately 0.4 ml/min/year. Our study provides age- and gender-specific reference values of GFR in a population of Caucasian persons without identifiable risk.

Contains fulltext : 53016.pdf (publisher's version ) (Closed access), The dihydrofolate reductase (DHFR) enzyme is important for folate availability, folate turnover and DNA synthesis. The 19-bp deletion in intron-1 of DHFR has been associated with the risk of having spina bifida affected offspring, supposedly by changing DHFR gene expression. A 9-bp repeat in exon 1 of the mutS homolog 3 (MSH3) gene was recently demonstrated to be also located in the 5'UTR of DHFR and may possibly affect DHFR gene expression as well. We examined the association between these DHFR variants and spina bifida risk and investigated their effect on DHFR expression. Our study population, consisting of 121 mothers of a spina bifida affected child, 109 spina bifida patients, 292 control women and 234 pediatric controls was screened for the DHFR 19-bp deletion and the DHFR 9-bp repeat. DHFR gene expression was measured in 66 spina bifida patients, using real-time PCR analysis. In this study population, the DHFR 19-bp del/del genotype was not associated with spina bifida risk in mothers and children (OR: 0.8; 95%CI: 0.4-1.5 and OR: 1.2; 95%CI: 0.6-2.2, respectively) and both the WT/del and the del/del genotype did not affect DHFR expression relative to the WT/WT genotype (relative expression=0.89, p=0.46 and relative expression=1.26, p=0.24, respectively). The DHFR 9-bp repeat was not associated with spina bifida risk in mothers and children. DHFR expression of the 6/6 allele was 73% increased compared to the 3/3 allele, although not significantly (relative expression=1.73, p=0.09). We did not find evidence for an effect of the DHFR 19-bp deletion or 9-bp repeat on spina bifida risk in mothers and children. An effect of the 6/6 repeat genotype on DHFR expression cannot be ruled out.

Contains fulltext : 52674.pdf (publisher's version ) (Closed access), Disturbances in folate metabolism may increase the risk of certain malignancies, congenital defects and cardiovascular diseases. The gene dihydrofolate reductase (DHFR) is primarily involved in the reduction of dihydrofolate, generated during thymidylate synthesis, to tetrahydrofolate in order to maintain adequate amounts of folate for DNA synthesis and homocysteine remethylation. In order to reveal possible variation that may affect plasma total homocysteine (tHcy), serum folate and red blood cell (RBC) folate levels, we sequenced the DHFR coding region as well as the intron-exon boundaries and DHFR flanking regions from 20 Caucasian individuals. We identified a 9-bp repeat in the 5'-upstream region that partially overlapped with the 5'-untranslated region, and several single-nucleotide polymorphisms, all in non-coding regions. We screened subjects for the 9-bp repeat (n=417), as well as the recently reported 19-bp deletion in intron 1 (n=330), and assessed their associations with plasma tHcy, serum and RBC folate levels. The 19-bp del/del genotype was associated with a lower plasma tHcy (-14.4% [95% confidence interval: -23.5 to -4.5], P=0.006) compared with the wild-type genotype. This may suggest that intracellular folate levels are affected.

Contains fulltext : 51621.pdf (publisher's version ) (Closed access), The Vitamins and Thrombosis (VITRO) study investigated the effect of homocysteine lowering by daily supplementation of B vitamins on the risk reduction of deep vein thrombosis (DVT) and pulmonary embolism (PE). Patients between 20 to 80 years old with a first objectively confirmed proximal DVT or PE in the absence of major risk factors and a homocysteine concentration above the 75th percentile of a reference group were asked to participate (hyperhomocysteinemic group). A similar study was conducted in a random sample of patients with a homocysteine below the 75th percentile of the reference group (normohomocysteinemic group). After informed consent was obtained, patients were randomized to daily multivitamin supplementation (5 mg folic acid, 50 mg pyridoxine, and 0.4 mg cyanocobalamin) or placebo and were followed for 2.5 years. End points were objectively diagnosed recurrent DVT or PE. A total of 701 patients were enrolled (360 in the hyperhomocysteinemic and 341 in the normohomocysteinemic group). The number of recurrent events of venous thrombosis was 43 of 353 in the vitamin group (54/1000 py) and 50 of 348 in the placebo group (64/1000 py). The hazard ratio associated with vitamin treatment was 0.84 (95% CI, 0.56-1.26): 1.14 (95% CI, 0.65-1.98) in the hyperhomocysteinemic group and 0.58 (95% CI, 0.31-1.07) in the normohomocysteinemic group. The results of our study do not show that homocysteine lowering by B vitamin supplementation prevents recurrent venous thrombosis.

Contains fulltext : 51838.pdf (publisher's version ) (Closed access)

Contains fulltext : 51642.pdf (publisher's version ) (Closed access), The 894G>T single nucleotide polymorphism (SNP) in the endothelial NOS (NOS3) gene, has recently been associated with embryonic spina bifida risk. In this study, a possible association between the NOS3 894G>T SNP and spina bifida risk in both mothers and children in a Dutch population was examined using both a case-control design and a transmission disequilibrium test (TDT). Possible interactions between the NOS3 894G>T SNP and the MTHFR 677C>T SNP, elevated plasma homocysteine, and decreased plasma folate concentrations were also studied. The NOS3 894TT genotype did not increase spina bifida risk in mothers or children (OR 1.50, 95%CI 0.71-3.19 and OR 1.78, 95%CI 0.75-4.25, respectively). The TDT demonstrated no preferential transmission of the NOS3 894T allele (Chi2=0.06, P=0.81). In combination with the MTHFR 677TT genotype or elevated plasma homocysteine concentrations, the NOS3 894GT/TT genotype increased maternal spina bifida risk (OR 4.52, 95%CI 1.55-13.22 and OR 3.38, 95%CI 1.46-7.84, respectively). In our study population, the NOS3 894GT/TT genotype might be a risk factor for having a spina bifida affected child in mothers who already have an impaired homocysteine metabolism.

Contains fulltext : 53641.pdf (publisher's version ) (Closed access), BACKGROUND: Periconceptional folic acid supplementation may protect against congenital heart defects (CHDs). Identification of candidate genes in folate metabolism has suggested that the 677C-->T polymorphism in the methylenetetrahydrofolate reductase (MTHFR) gene may be particularly associated with the risk of CHDs. AIM: To assess the relationship between MTHFR 677C-->T and CHDs by literature review and meta-analysis. METHODS: Studies were identified by searches of electronic literature for papers focussing on MTHFR 677C-->T and the risk of any type of CHD. Both case-control comparisons and transmission-disequilibrium tests (TDTs) in family-based designs were included. RESULTS: We found 13 eligible studies. Of 10 case-control studies, four focused on the fetal polymorphism, two studied the maternal polymorphism, and a further four investigated both. Three further publications used a family-based association study to assess the effect of the T allele on cardiac development. Overall analysis yielded odds ratios of 1.3 (95%CI 0.97-1.73) and 1.2 (95%CI 0.83-1.74) for fetal and maternal MTHFR TT genotypes, respectively. TDTs revealed no association between fetal 677T allele and CHDs. DISCUSSION: This relatively small meta-analysis found no substantial evidence of increased CHD risk in individuals with MTHFR 677CT and TT genotypes. Heterogeneity regarding population background, study design and type of heart defects complicates the pooling and comparison of the studies. The effect of modification by periconceptional folic acid intake should be taken into account. Further larger studies and well-defined phenotypic subcategory analyses are needed to decide whether the MTHFR 677C-->T polymorphism of the affected child and/or their mother is truly a risk factor for the development of CHDs.

Contains fulltext : 51448.pdf (publisher's version ) (Closed access), BACKGROUND: Hyperhomocysteinemia has been associated with vascular disease in many epidemiological studies. However, the pathophysiology is unclear. It is postulated that increased levels of homocysteine induce an inflammatory response in endothelial cells, mediated by pro-inflammatory cytokines and chemokines. The aim of this study was to investigate whether plasma concentrations of interleukin-6, interleukin-8, C-reactive protein, and monocyte chemoattractant protein-1 are increased with higher plasma homocysteine concentrations and whether decreasing homocysteine by vitamin supplementation decreases the concentration of these markers. METHODS: Plasma homocysteine, interleukin-6, interleukin-8, C-reactive protein, and monocyte chemoattractant protein-1 concentrations were measured in 230 volunteers before and after 8 weeks of multivitamin supplementation (folic acid, B(6), and B(12)). RESULTS: At baseline, plasma homocysteine concentration was weakly associated with interleukin-8, but not with interleukin-6, C-reactive protein or monocyte chemoattractant protein-1. Vitamin supplementation resulted in a significant decrease in homocysteine concentration, but no effect on interleukin-6, interleukin-8, C-reactive protein or monocyte chemoattractant protein-1 was observed. CONCLUSIONS: At baseline homocysteine was only weakly correlated with interleukin-8, but not with interleukin-6, C-reactive protein or monocyte chemoattractant protein-1. Vitamin supplementation affected homocysteine concentration, but not cytokine levels. The hypothesis that hyperhomocysteinemia increases arteriosclerotic or thrombotic risk through vascular inflammation was not supported by this study.