Biomedical subjects
Publications and source records attributed to Stefan Schreiber.
We performed a genome-wide association study of 19,779 nonsynonymous SNPs in 735 individuals with Crohn disease and 368 controls. A total of 7,159 of these SNPs were informative. We followed up on all 72 SNPs with P 0.4), these data suggest that the underlying biological process may be specific to Crohn disease.
BACKGROUND: Gallstones represent a prevalent and costly health problem. The changing epidemiology and the emerging non-surgical interventions for gallstone disease necessitate the definition of target populations for future therapies. This study aimed to define patterns of gallstone composition and identify demographic predictors of gallstone composition in a large sample of symptomatic gallstones from Northern Germany. METHODS: One thousand and seventy-four post-cholecystectomy gallstone specimens were obtained. Demographic and clinical information was provided by questionnaire (N = 1025 independent individuals with complete information). Two samples from each gallstone were analyzed using Fourier transformed infrared spectrometry. RESULTS: The most prevalent substance was cholesterol, which was detected in 95.0% of gallstone specimens. Bilirubin and bilirubinate were present in 30.0% and calcium was detected in 10.0% of the spectra. Ninety-two percent of measurements from the same stone yielded the same "main" substances, indicating a homogenous stone composition in most cases. Female sex and higher body mass index (BMI) were associated with the presence of cholesterol as a main substance in the gallstones (p < 0.001). CONCLUSION: The changing epidemiology of gallstone disease is reflected by a marked shift in stone composition: Only two percent of stones in this study were pigment stones as compared to 91% percent of stones containing cholesterol as a main substance. Obese individuals from Germany with a BMI > 30 kg/m2 have in 95% cholesterol-dominant gallstones and represent a potential target population for non-surgical interventions for the prevention or treatment of cholesterol stones.
OBJECTIVES: Approximately 80% of patients with primary sclerosing cholangitis (PSC) of Northern European origin have concurrent inflammatory bowel disease (IBD). The majority have ulcerative colitis, but there is also an association with Crohn's colitis. The pathogenetic link between PSC and IBD is unknown. We aimed to assess whether genetic risk factors in PSC can be identified on the basis of known IBD susceptibility genes and the shared PSC-IBD phenotype. METHODS: IBD-associated polymorphisms in the CARD15, TLR-4, CARD4, SLC22A4, SLC22A5, DLG5, and MDR1 genes were genotyped in a large cohort of 365 Scandinavian PSC patients and 368 healthy controls using TaqMan technology. RESULTS: No significant association between any of the investigated genetic IBD risk variants and overall susceptibility to PSC was observed. Apart from a tendency toward an increased carrier frequency of the mutant CARD15 alleles in PSC patients with concurrent Crohn's disease as compared with healthy controls (15.6%vs 9.0%, P = 0.22), no association with any of the polymorphisms investigated was evident even when considering only PSC patients with concurrent IBD. CONCLUSION: It seems unlikely that IBD-associated polymorphisms in the CARD15, TLR-4, CARD4, SLC22A4, SLC22A5, DLG5, and MDR1 genes confer susceptibility to PSC. The current knowledge of genetic risk factors in IBD may not contribute to our understanding of molecular mechanisms involved in the pathogenesis of PSC or the IBD phenotype in PSC.
Explore the source record for details and available documents.
Tuberculosis (TB) is one of the leading causes of death worldwide. The nucleotide-binding oligomerisation domain 2 protein (NOD2) has recently been recognised as a non-redundant recognition mechanism of Mycobacterium tuberculosis. The caspase recruitment domain-containing protein 15 gene (CARD15), which encodes the NOD2 protein, is a susceptibility gene for Crohn's disease (CD), a granulomatous, chronic inflammatory disorder. CARD15 was therefore investigated as a candidate gene in TB. We genotyped the R702W, G908R and 1007fs variants, previously associated with CD, in TB cases and controls from the admixed South African Coloured population. No statistically significant differences between cases and controls were observed for these variants. We determined that the CD-associated mutations occur at very low frequencies in this population. Our results indicate that CARD15 is not a major susceptibility gene for TB in the South African Coloureds.
AIM: To investigate whether the stimulation of peripheral blood mononuclear cells (PBMNC) with the cell debris and cell extraction of different probiotic strains is similar or species specific. METHODS: Three strains of bifidobacteria, 4 strains of lactobacilli, and E. coli nissle were sonicated and centrifuged in order to divide them into cell extract and cell debris. PBMNC were separated by density gradient and incubated for 36 h with either the cell debris or the cell extract of single strains of probiotic bacteria in doses from 10(2) to 10(8) CFU/mL. Cell supernatants were taken and interleukin (IL)-10, IL-1beta, and tumor necrosis factor (TNF)-alpha were determined by ELISA. RESULTS: Depending on the species super-family, the strains had different stimulation patterns. Except for both L. casei strains, the cell extract of bifidobacteria and lactobacilli had less stimulating capacity than cell debris, whereas the cell extract of E. coli nissle had similar stimulating properties to that of the cell debris of the strain and significantly more stimulating capacity than that of bifidobacteria and lactobacilli. The cell debris of bifidobacteria stimulated more cytokine release than the cell debris of lactobacilli. The cell debris of lactobacilli did not have a stimulating capacity when lower concentrations were used. Neither cell extraction nor cell debris had an inhibitory effect on the production of the tested cytokines by stimulated PBMNC. CONCLUSION: The incubation of probiotic strains, which have been used in clinical trials for inflammatory diseases, with immunocompetent cells leads to different species specific reactions. High IL-10 response to cell debris of bifidobacteria and E. coli nissle can be found. This corresponds to positive effects of bifidobacteria and E. coli nissle in clinical trials for inflammatory bowel disease compared to negative outcomes obtained with lactobacilli.
OBJECTIVE: To evaluate the relevance and necessity to account for the effects of population substructure on association studies under a case-control design in central Europe, we analysed three samples drawn from different geographic areas of Germany. Two of the three samples, POPGEN (n = 720) and SHIP (n = 709), are from north and north-east Germany, respectively, and one sample, KORA (n = 730), is from southern Germany. METHODS: Population genetic differentiation was measured by classical F-statistics for different marker sets, either consisting of genome-wide selected coding SNPs located in functional genes, or consisting of selectively neutral SNPs from 'genomic deserts'. Quantitative estimates of the degree of stratification were performed comparing the genomic control approach [Devlin B, Roeder K: Biometrics 1999;55:997-1004], structured association [Pritchard JK, Stephens M, Donnelly P: Genetics 2000;155:945-959] and sophisticated methods like random forests [Breiman L: Machine Learning 2001;45:5-32]. RESULTS: F-statistics showed that there exists a low genetic differentiation between the samples along a north-south gradient within Germany (F(ST)(KORA/POPGEN): 1.7 . 10(-4); F(ST)(KORA/SHIP): 5.4 . 10(-4); F(ST)(POPGEN/SHIP): -1.3 . 10(-5)). CONCLUSION: Although the F(ST )-values are very small, indicating a minor degree of population structure, and are too low to be detectable from methods without using prior information of subpopulation membership, such as STRUCTURE [Pritchard JK, Stephens M, Donnelly P: Genetics 2000;155:945-959], they may be a possible source for confounding due to population stratification.
Carnosine, a cytoprotective dipeptide found at very high concentrations in skeletal muscle, heart and brain, is cleaved in blood by serum carnosinase which is encoded by the CNDP1 gene. We recently found that homozygosity of a 5-leucine variant in the leader peptide of this enzyme protects diabetes mellitus patients against nephropathy. Hypothesising that the same allele could also be associated with longevity or a reduced incidence of cardiovascular problems, we examined the frequency of CNDP1 alleles in German centenarians, patients with premature coronary heart disease, and matched controls. A total of 1382 individuals was investigated. The 5-leucine allele was the most common allele in all groups investigated. There was no difference in allele or genotype frequency between centenarians and their control group, or between cardiovascular patients and their control group. The recently identified functional carnosinase variant therefore does neither contribute to longevity nor protect against coronary heart disease in our probands. In addition to the known trinucleotide repeat alleles in the CNDP1 gene, we detected a rare 8-leucine allele, a rare duplication, p.L13_V15dup, and a more common frameshift deletion, L17fsX20. Homozygosity for L17fsX20, estimated to have a prevalence of approximately 1:20,000, would be expected to cause carnosinaemia, an autosomal recessive trait with uncertain clinical relevance.
BACKGROUND AND AIMS: Onercept is a recombinant, soluble human p55 receptor to tumor necrosis factor-alpha. METHODS: A randomized, double-blind, placebo-controlled, dose-ranging trial was performed to evaluate the efficacy of onercept induction therapy in patients with Crohn's disease (CD). Patients (n = 207) with moderate-to-severe acute or chronic active CD were randomized to receive subcutaneous onercept (10, 25, 35, or 50 mg) or placebo 3 times weekly for 8 weeks. Primary analysis was induction of remission (defined as a CD activity index score < or = 150) at week 8. RESULTS: A total of 104 patients had acute active CD. Remission rates at week 8 were 23.5% for placebo (n = 17), and 34.8%, 20.0%, 26.1%, and 28.6% for onercept 10 mg (n = 23), 25 mg (n = 20), 35 mg (n = 23), and 50 mg (n = 21), respectively (P = .98). A total of 103 patients had chronic active CD. Remission rates at week 8 were 23.8% for placebo (n = 21), and 23.8%, 9.1%, 35.3%, and 13.6% for onercept 10 mg (n = 21), 25 mg (n = 22), 35 mg (n = 17), and 50 mg (n = 22), respectively (P = .66). There were no differences between treatment groups in the incidence of adverse events. However, mild-to-moderate injection-site reactions occurred in up to 12% of onercept-treated patients. CONCLUSIONS: Onercept was well tolerated but was not effective at the doses studied in patients with active CD.
To investigate the effect of long-term consumption of probiotic bacteria on viral respiratory tract infections (common cold, influenza), a randomized, double blind, controlled intervention study was performed during two winter/spring periods (3 and 5 month). Four hundred and seventy-nine healthy adults were supplemented daily with vitamins plus minerals with or without probiotic lactobacilli and bifidobacteria. The intake of the probiotic had no effect on the incidence of common cold infections (verum=158, control=153 episodes, influenza was not observed), but significantly shortened duration of episodes by almost 2 days (7.0+/-0.5 versus 8.9+/-1.0 days, p=0.045), reduced the severity of symptoms and led to larger increases in cytotoxic T plus T suppressor cell counts and in T helper cell counts.
BACKGROUND AND AIMS: Mutations in the DLG5 gene are associated with an increased risk of inflammatory bowel disease (IBD) in some European populations. Initial investigation of a British IBD population showed evidence of association of one of three DLG5 variants, R30Q, in a family-based collection but not in a case-control cohort. We have now examined the association of the R30Q polymorphism in a large cohort of British IBD cases, tested for interaction between the DLG5 and CARD15 genes and assessed possible association of DLG5 with clinical features of Crohn's disease (CD) and ulcerative colitis (UC). MATERIALS AND METHODS: DLG5 R30Q and the CARD15 polymorphisms, Arg702Trp, Gly908Arg and Leu1007fs were genotyped in 1,148 IBD cases and 749 controls. DLG5 R30Q was also analysed in cases stratified by CARD15 genotype, disease subtype and smoking history. RESULTS/FINDINGS: No significant difference in frequencies of the R30Q variant was observed between IBD cases (9.9%) and controls (10.1%) or in cases analysed separately as CD and UC. There was also no significant difference in the frequency of R30Q between CD cases carrying risk-associated CARD15 alleles and those that did not. The frequency of R30Q was higher in CD cases with ileal disease than cases without (p=0.042) and higher in CD cases who had smoked than in nonsmokers (p=0.009). INTERPRETATION/CONCLUSION: The R30Q variant in the DLG5 gene does not appear to be associated with an overall increase in the risk of disease in a British IBD cohort, but differences in its frequency in subgroups of CD patients warrant further investigation.
Signals of Notch transmembrane receptors function to regulate a wide variety of developmental cell fates. Here we investigate the role of Notch signaling in the development of mesodermal cell types by expressing a tamoxifen-inducible, activated form of Notch1 in embryonic stem cells (ESC). For differentiation of ESC into first mesodermal progenitor cells and then endothelial, mural, cardiac muscle and hematopoietic cells, the OP9 stroma co-culture system was used. Timed activation of Notch signaling by the addition of tamoxifen at various stages during differentiation of ESC into mesodermal cell lineages results in profound alterations in the generation of all of these cells. Differentiation of ESC into Flk1(+) mesodermal cells is inhibited by activated Notch. When Notch signaling is activated in mesodermal cells, generation of cardiac muscle, endothelial and hematopoietic cells is inhibited, favoring the generation of mural cells. Activation of Notch signaling in hematopoietic cells reduces colony formation and maintenance of hematopoiesis. These data suggest that Notch signaling plays a regulatory role in mesodermal development, cardiomyogenesis, the balanced generation of endothelial versus mural cells of blood vessels and hematopoietic development.
The microsomal triglyceride transfer protein (MTP) is required for the assembly and secretion of apolipoprotein B-containing lipoproteins. Emerging evidence has indicated that the functional MTP exon polymorphism I128T is associated with dyslipidemia and other traits of the insulin-resistance syndrome, and the T128 variant seems to confer a reduced stability of MTP, resulting in reduced binding of LDL particles. The aim of the study was to elucidate the association of this MTP polymorphism with parameters of postprandial metabolism. A total of 716 male subjects from a postprandially characterized cohort (MICK) and a nested case-control study (EPIC) of 190 incident type 2 diabetes cases and 380 sex- or age-matched controls were genotyped for the I128T exon polymorphism. In comparison to homozygote subjects of the wild allele, carriers of the less common allele of the MTP T128 genotype showed significantly lower postprandial insulin levels (P=0.017), lower diastolic blood pressure (P=0.049) and had a lower prevalence of impaired glucose metabolism and diabetes type 2 (P=0.03) in the MICK. Consistent with this, we found a lower incidence of type 2 diabetes in male subjects of the nested case-control study in the T128 genotype (P=0.007). These results suggest that the rare allele of the MTP I128T polymorphism may be protective against impaired glucose tolerance, type 2 diabetes and other parameters of the metabolic syndrome.
In Pyrosequencing, the addition of nucleotides to a primer-template hybrid is monitored by enzymatic conversion of chemical energy into detectable light. The technique yields both qualitative and quantitative sequence information because the chemical energy is released by a stoichiometric split off of pyrophosphates from incorporated deoxynucleotide triphosphates and a defined nucleotide dispensation order is given. Because Pyrosequencing works best if single-stranded DNA templates are used, template generation usually requires PCR with a target-specific biotinylated primer and a subsequent purification involving interaction of the biotin label with immobilized streptavidin. To circumvent the need for numerous and expensive template-specific biotinylated primers, we developed a method that uses the ligation of amplified DNA fragments into a plasmid vector, thereby facilitating subsequent PCR using a universal vector-specific biotinylated primer. This approach allows easy and straightforward isolation of single-stranded templates of any PCR product. As a proof of principle, we used the method for genotyping two single-nucleotide polymorphisms in the human genes CARD15 and A2M and for characterization of four multisite variations in the human DEFB104 gene.
Alterations in splicing patterns of genes contribute to the regulation of gene function by generating endogenous inhibitor or activator molecules. Nucleotide-binding and oligomerization domain (NOD) 2 is an intracellular receptor for bacterial cell wall components and plays an important role in initiating immune responses against cytoinvasive pathogens. NOD2 overexpression sensitizes intestinal epithelial cells toward bacterial cell wall components, activates the proinflammatory transcription factor NF-kappaB, and induces the subsequent release of the chemotactic cytokine IL-8. Here, we have assessed the regulation and function of a transcript isoform of NOD2, NOD2-S, generated by the skipping of the third exon, which encodes for a protein that is truncated within the second caspase recruitment (CARD) domain. NOD2-S is preferentially expressed in the human colon and is up-regulated by the antiinflammatory cytokine IL-10. Overexpression of NOD2-S down-regulates NOD2-induced NF-kappaB activation and IL-8 release. Moreover, NOD2-S also interferes with the maturation and secretion of pro-IL-1beta downstream of NOD2 and its adaptor molecule receptor-interacting protein kinase 2. We provide a molecular basis for these effects, as we show that NOD2-S interacts with both, NOD2 and receptor-interacting protein kinase 2 and inhibits the "nodosome" assembly by interfering with the oligomerization of NOD2. These data unveil another level of complexicity in the regulation of intracellular innate immunity and may have important implications for the molecular understanding of NOD/NALP protein-driven disease pathophysiology.
BACKGROUND: Bacterial infection has been discussed as a potential etiologic factor in the pathophysiology of coronary heart disease (CHD). This study analyzes molecular phylogenies to systematically explore the presence, frequency, and diversity of bacteria in atherosclerotic lesions in patients with CHD. METHODS AND RESULTS: We investigated 16S rDNA signatures in atherosclerotic tissue obtained through catheter-based atherectomy of 38 patients with CHD, control material from postmortem patients (n=15), and heart-beating organ donors (n=11) using clone libraries, denaturating gradient gel analysis, and fluorescence in situ hybridization. Bacterial DNA was found in all CHD patients by conserved PCR but not in control material or in any of the normal/unaffected coronary arteries. Presence of bacteria in atherosclerotic lesions was confirmed by fluorescence in situ hybridization. A high overall bacterial diversity of >50 different species, among them Staphylococcus species, Proteus vulgaris, Klebsiella pneumoniae, and Streptococcus species, was demonstrated in >1500 clones from a combined library and confirmed by denaturating gradient gel analysis. Mean bacterial diversity in atheromas was high, with a score of 12.33+/-3.81 (range, 5 to 22). A specific PCR detected Chlamydia species in 51.5% of CHD patients. CONCLUSIONS: Detection of a broad variety of molecular signatures in all CHD specimens suggests that diverse bacterial colonization may be more important than a single pathogen. Our observation does not allow us to conclude that bacteria are the causative agent in the etiopathogenesis of CHD. However, bacterial agents could have secondarily colonized atheromatous lesions and could act as an additional factor accelerating disease progression.
The competence network chronic inflammatory bowel disease (KN-CED) is one of 17 networks of competence initiated by the German Federal Ministry of Education and Research (BMBF). These networks are concerned with disease patterns which are characterized by their high frequency, high mortality rate or which present a large expense factor. The project-executing organization is the German Center for Air and Space Travel (DLR e. V.). The central structure of organization is the Telematic Platform for medical Networks (TMF e. V.). Aim of the KN-CED is to investigate, in their complexity, the incurable chronic diseases ulcerative colitis and Crohn's disease, particularly with regard to the causes of disease, the establishment of new therapy standards as well as patient care. To achieve this goal, the competence network is integrated into both national and international research associations and is also backed by the national self-help group DCCV and the pharmaceutical industry. Principal items of the competence network are the core facilities and their main focus on molecular genetics, animal and cell models and serum markers. Having stored the data of more than 4,000 patients so far, the central database of the competence network is one of the largest databases worldwide with regard to inflammatory bowel disease (IBD). The successful cooperation within the network is reflected in numerous publications. Thus, two of the three known genes of Crohn's disease were identified. Also with the participation of the competence network national guidelines for the diagnosis and therapy of IBD were generated.Furthermore, the competence network operates study centers where significant therapeutic developments in the field of biotechnological drugs are taking place. The analysis of existing structures of care as well as the development of standards of organization for patients with IBD top the research within the competence network and emphasize the claim to find comprehensive answers to the questions connected with IBD.
Recently, we described the association of genetic variation in the discs large homolog 5 (DLG5) gene with inflammatory bowel disease (IBD) in a large European study sample (Stoll et al. in Nat Genet 36:476-480, 2004). Here, we report that the R30Q variant constitutes a susceptibility factor for Crohn disease (CD) in men [odds ratio (OR)=2.49, 95% confidence interval (CI) 1.53-4.06, P<0.001] but not women (OR=1.01, 95% CI=0.70-1.45, P=0.979) using multivariate logistic regression analyses in a unified study sample from Germany, Italy and Quebec. R30Q is a significant predictor for CD in men even when accounting for CARD15 and IBD5 risk variants (adjusted OR=2.41, 95% CI=1.41-4.12, P=0.001). The observed association is driven by a gender-dependent transmission ratio distortion (TRD) among healthy controls (frequency of Q allele: men 5.2%, women 11.3%), an effect that is offset in CD patients (frequency of Q allele: men 10.1%, women 10.9%). This finding is further substantiated by two non-IBD study samples, one of which consists of a newborn screening sample (newborn males 7.1%; newborn females 11%, P=0.036). Further investigation of the observed TRD may contribute towards enlightening the role of DLG5 in physiological processes influencing transmission of chromosomes to the surviving offspring, which, in turn, may help in understanding its implication in the development of CD among men.