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Biomedical subjects

S Nikolaus

Publications and source records attributed to S Nikolaus.

At least 19 recordsLinked to original sources
PubMed2006

Detection of diverse bacterial signatures in atherosclerotic lesions of patients with coronary heart disease.

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.

Adult↗
PubMed2006

The FCGR2A--Arg131 variant is no major mortality factor in the elderly--evidence from a German centenarian study.

The functional single nucleotide polymorphism rs1801274 in the FCGR2A gene (His131Arg) influences the efficiency of hIgG2 binding, the main isotype produced in response to encapsulated bacteria like Streptococcus pneumoniae and Haemophilus influenzae. In contrast to the receptor with the His131 allele, FcgammaRIIa-Arg131 binds hIgG2 poorly and carriers of this variant have been shown to be much more susceptible to succumb to bacterial pneumonia or meningitis. As bacteraemic pneumonia is one of the leading causes of death in elderly individuals, we hypothesized that the Arg131 variant could be a major mortality factor in the old. We analysed the FCGR2A-His131Arg polymorphism in a group of 408 German centenarians and two samples of younger Germans aged 60-75 and 18-49 years, respectively. No statistically significant differences were observed between the three age groups, neither at the allele nor at the genotype level. Apparently, the ability to reach old age is largely unaffected by the genetically determined efficacy of the FCGR2A-based immune response. However, the severely reduced ability of FCGR2A-131Arg carriers to eliminate encapsulated bacteria must apparently be compensated by an alternative mechanism, possibly involving other genetic survival factors.

Adolescent↗
PubMed2005

[Pharmacologic therapy for inflammatory bowel diseases: hopes, disappointments].

Because the etiology of inflammatory bowel diseases is unclear, no causative therapy is available. However, pathophysiology of the disease offers a lot of possibilities to disrupt the inflammatory cascade that maintains the inflammatory process. The aim of every therapy is to maintain remission as long as possible and to amend the natural course of the disease. Pharmacotherapy includes 5-Aminosalicylates, glucocorticoids, immunosupressants (methotrexate, azathioprine) as well as specific pharmacologic interventions like monoclonal antibodies directed against TNF-alpha (Infliximab). Important supportive tools are available to improve symptoms like diarrhea and pain. Dietetic treatment and surgical procedures represent important alternatives or supplement pharmacotherapeutic interventions.

Anti-Inflammatory Agents↗
PubMed2005

[State-of-the-art of small animal imaging with high-resolution SPECT].

During the recent years, in vivo imaging of small animals using SPECT has become of growing relevance. Along with the development of dedicated high-resolution small animal SPECT cameras, an increasing number of conventional clinical scanners has been equipped with single or multipinhole collimators. This paper reviews the small animal tomographs, which are operating at present and compares their performance characteristics. Furthermore, we describe the in vivo imaging studies, which have been performed so far with the individual scanners and survey current approaches to optimize molecular imaging with small animal SPECT.

Animals↗
PubMed2004

Definition of polymorphisms and haplotypes in the interleukin-12B gene: association with IL-12 production but not with Crohn's disease.

Interleukin-12 (IL-12) is a key cytokine for the induction of Th1 immune responses. Recently, functional polymorphisms in IL-12p40 (IL12B) were found to be associated with susceptibility to several autoimmune diseases. Similarly, variation in IL12B might be involved in susceptibility to Crohn's disease (CD), a chronic inflammatory bowel disorder associated with high IL-12 expression. We searched for additional polymorphism in IL12B and genotyped a large cohort of CD patients. Differential in vitro secretors of IL-12 were tested for polymorphism. Polymorphisms were analyzed using the intrafamilial transmission disequilibrium test (TDT) and by case-control analysis. A novel polymorphism was strongly associated with differential expression of IL-12. However, no association with susceptibility to CD was seen for this and other polymorphisms. The high level of conservation is consistent with the key regulatory role of IL-12. The lack of association with IL12B makes it unlikely that this gene is directly involved in the susceptibility to CD.

Base Sequence↗
PubMed2004

Depression and anxiety in different thyroid function states.

Previous studies on hypothyroid subjects have indicated serious psychiatric symptoms affecting the patients' quality of life. The present prospective cross-sectional study's aim was to examine these symptoms in thyroid patients with different functional states. A total of 254 patients (age: 56 +/- 14 years [mean +/- standard deviation], 181 female, 73 male) referred to a hospital for radioiodine treatment of hyperthyroidism or for follow-up of differentiated thyroid cancer, respectively, were included. All patients underwent the twelve-item general health questionnaire, which is an instrument for detecting mood disturbances. Euthyroid and hyperthyroid patients did not differ significantly in their general health questionnaire score (11 +/- 5 vs. 11 +/- 7), nor did subclinical hyperthyroid (11 +/- 6) or subclinical hypothyroid subjects (12 +/- 5). In contrast, hypothyroid patients showed a significantly higher mean score (17 +/- 7, p < 0.001, ANOVA). Binary logistic regression revealed that hypothyroidism increases age and gender-adjusted risk for critical mood deterioration by seven-fold. Thus, hypothyroidism represents a widely underestimated functional condition that may severely affect mental health.

Adult↗
PubMed2004

Review article: exploration of the genetic aetiology of inflammatory bowel disease--implications for diagnosis and therapy.

Genomic technologies offer new approaches to the investigation of the aetiology and pathophysiology of inflammatory bowel disease. An important field relevant to inflammatory bowel disease therapy is the pharmacogenetic investigation of gene variations that may predict responses to certain medications in order to target these therapeutic interventions more precisely. To date, only about 12,000 of the estimated 30,000-50,000 human genes have been characterized. Therefore, the use of techniques for a global analysis of gene expression may allow the identification of new pathways or molecules in the therapeutic mechanisms of drugs. Recently, NOD2 has been identified as the first disease gene in inflammatory bowel disease. DLGS and OCTN-1 have been named as further disease genes. Although the detection of disease-associated variants has greatly advanced our understanding of the primary events that lead to the development of inflammatory bowel disease in a subgroup of patients with Crohn's disease, the implications of the findings for diagnostic and therapeutic algorithms are less clear. However, it appears that there is a clear association between certain subphenotypes of Crohn's disease and the disease-associated variants in the NOD2 gene. It can be anticipated that genomic findings will profoundly influence the future therapy of inflammatory bowel disease.

Gastrointestinal Agents↗
PubMed2003

Interferon beta-1a in ulcerative colitis: a placebo controlled, randomised, dose escalating study.

BACKGROUND: and aims: Administration of interferon (IFN)-beta may represent a rational approach to the treatment of ulcerative colitis through its immunomodulatory and anti-inflammatory effects. The present study was performed to evaluate the efficacy and tolerability of IFN-beta-1a. METHODS: Patients (n=18) with moderately active ulcerative colitis were randomised to receive IFN-beta-1a or placebo. IFN-beta-1a was started at a dose of 22 micro g three times a week subcutaneously, and the dose was increased at two week intervals to 44 micro g and then to 88 micro g if no response was observed. The maximum duration of treatment was eight weeks. End points were clinical treatment response, defined as a decrease of at least 3 points from baseline in the ulcerative colitis scoring system (UCSS) symptoms score and induction of endoscopically confirmed remission. RESULTS: Baseline characteristics and disease severity were similar in both groups. Data from 17 patients are included in this report (10 patients in the IFN-beta-1a group and seven patients in the placebo group). Clinical response was achieved in five patients (50%) in the IFN-beta-1a group and in one (14%) in the placebo group (P=0.14). Remission was achieved in three patients in the IFN-beta-1a group and in none in the placebo group (p=0.02). Most adverse reactions associated with IFN-beta-1a were influenza-like symptoms or injection site reactions, and were mild or moderate in severity. CONCLUSIONS: IFN-beta-1a may represent a promising novel treatment approach in ulcerative colitis.

Adjuvants, Immunologic↗
PubMed2002

Activation of signal transducer and activator of transcription (STAT) 1 in human chronic inflammatory bowel disease.

BACKGROUND: Increased expression of proinflammatory cytokines, including tumour necrosis factor alpha, interleukin 6, and interferon gamma, as well as activation of proinflammatory signalling molecules such as nuclear factor kappa B, is characteristic of inflammatory bowel disease (IBD). AIMS: To investigate expression and activation of signal transducer and activator of transcription (STAT) 1 in patients with IBD. PATIENTS: Patients with active IBD (n=42), disease specificity controls (n=8), and normal controls (n=12) were investigated. METHODS: Expression and activation of STAT1 were assessed by western blotting and electrophoretic mobility shift assays in extracts of endoscopic colonic biopsies. Cellular localisation was determined by immunohistochemistry. RESULTS: Western blots and immunohistochemical staining revealed an increase in STAT1 expression and activation in mucosal samples from ulcerative colitis and to a lesser extend in Crohn's disease patients. High levels of suppressor of cytokine signalling (SOCS)-3 expression, an inhibitor of STAT activation, were observed in Crohn's disease patients and normal controls in western blot experiments whereas no differences were observed for SOCS-1 expression. Phosphorylated (p) STAT1 was mainly detected in monocytic cells and neutrophils in the inflamed mucosa. Induction of remission by systemic glucocorticoids led to a decrease in levels of pSTAT1. In vitro studies indicated a direct effect of steroid treatment on STAT1 activation. CONCLUSIONS: Expression and activation of STAT1 are predominantly heightened in ulcerative colitis and may therefore play an important role in the pathophysiology of colonic inflammation.

Anti-Inflammatory Agents↗
PubMed2002

Distribution of 5HT2A receptors in the human brain: comparison of data in vivo and post mortem.

AIM: The study presented here firstly compares the distribution of the binding potential of the serotonin-5HT2A receptor as measured in vivo with data of receptor density taken from literature. Secondly, the sensitivity of the method to detect gradual differences in receptor densities is evaluated. METHODS: Positron emission tomography (PET) studies were carried out in 6 healthy volunteers using the selective serotonin-5HT2A ligand 18F-altanserin. The binding potential was quantified in 12 regions using Logan's graphical method and the equilibrium method. These data were compared to the distribution of receptor density as taken from literature. RESULTS: The binding data in vivo correlated to autoradiography data (post mortem) with r = 0.83 (Pearson regression coefficient; p < 0.0001). A difference in the receptor density between two regions could be detected with p < 0.05 when it amounted at least to 18%. CONCLUSION: This study demonstrates a good agreement between in vivo data obtained with 18F-altanserin and PET in healthy volunteers and the true autoradiographically determined distribution of 5HT2A receptors in human brains. The in vivo method seems to be sensitive enough to detect changes in receptor density of more than 18%.

Adult↗
PubMed2001

Association between insertion mutation in NOD2 gene and Crohn's disease in German and British populations.

Background Genetic predisposition to inflammatory bowel disease (IBD) has been shown by epidemiological and linkage studies. Genetic linkage of IBD to chromosome 16 has been previously observed and replicated in independent populations. The recently identified NOD2 gene is a good positional and functional candidate gene since it is located in the region of linkage on chromosome 16q12, and activates nuclear factor (NF) kappaB in response to bacterial lipopolysaccharides. Methods We sequenced the coding region of the NOD2 gene and genotyped an insertion polymorphism affecting the leucine-rich region of the protein product in 512 individuals with IBD from 309 German or British families, 369 German trios (ie, German patients with sporadic IBD and their unaffected parents), and 272 normal controls. We then tested for association with Crohn's disease and ulcerative colitis. Findings Family-based association analyses were consistently positive in 95 British and 99 German affected sibling pairs with Crohn's disease (combined p<0.0001); the association was confirmed in the 304 German trios with Crohn's disease. No association was seen in the 115 sibling pairs and 65 trios with ulcerative colitis. The genotype-specific disease risks conferred by heterozygous and homozygous mutant genotypes were 2.6 (95% CI 1.5-4.5) and 42.1 (4.3-infinity), respectively. Interpretation The insertion mutation in the NOD2 gene confers a substantially increased susceptibility to Crohn's disease but not to ulcerative colitis.

Alleles↗
PubMed2001

Absence of efficacy of subcutaneous antisense ICAM-1 treatment of chronic active Crohn's disease.

BACKGROUND & AIMS: ISIS-2302, an antisense oligonucleotide directed against intercellular adhesion molecule 1, was effective in steroid refractory Crohn's disease in a pilot trial. The aim of this study was to investigate safety and efficacy of ISIS-2302 in chronic active Crohn's disease (CACD). METHODS: A dose-interval, multicenter, placebo-controlled trial was conducted in 75 patients with steroid-refractory CACD (Crohn's Disease Activity Index [CDAI], 200-400). The primary endpoint was steroid-free remission (CDAI <150) at week 14. RESULTS: Only 2 of 60 (3.3%) ISIS-2302-treated and no placebo patients reached the primary endpoint. Steroid-free remission at week 26 (secondary endpoint) was reached in 8 of 60 (13.3%) active treatment and 1 of 15 (6.7%) placebo patients. A greater proportion of ISIS-2302-treated than placebo patients achieved a steroid dose <10 mg/day at weeks 14 and 26 (48.3% vs. 33.3% and 55.0% vs. 40.0%, respectively, and a glucocorticoid dose of 0 mg [prednisone equivalent] at week 26 [23.3% vs. 6.7%, respectively]). Treatment with ISIS-2302 was safe. The most common side effects were injection site reactions in the active treatment group (23% in ISIS-2302-treated patients vs. none in placebo patients). No statistically significant differences in the frequency of side effects were detected between dose groups. CONCLUSIONS: The trial did not prove clinical efficacy of ISIS-2302 based on the primary endpoint. Positive trends were observed in some of the secondary endpoints.

Adult↗
PubMed2001

Increased expression of IL-16 in inflammatory bowel disease.

BACKGROUND: Inflammatory bowel disease (IBD) is characterised by infiltration of inflamed mucosal regions with CD4(+) T lymphocytes and other mononuclear cells. Interleukin (IL)-16 exerts a strong chemoattractant activity on CD4(+) cells. Moreover, IL-16 activates expression and production of proinflammatory cytokines such as IL-1beta, IL-6, IL-15, and tumour necrosis factor alpha (TNF-alpha) in human monocytes. AIM: To examine if IL-16 expression is increased in IBD patients compared with healthy controls. METHODS: Twenty one patients with IBD (10 with ulcerative colitis (UC), 11 with Crohn's disease (CD)), seven disease specificity controls (DSC), and seven healthy controls were studied. Biopsies were taken during colonoscopies and IL-16 mRNA as well as protein expression were investigated by reverse transcriptase-polymerase chain reaction, ELISA, western blot, and immunohistochemistry. RESULTS: IL-16 mRNA and protein expression in the colonic mucosa of IBD patients were increased twofold compared with healthy controls, DSC, or IBD patients under steroid treatment. Most of the detected IL-16 protein was in its bioactive 17 kDa form and was predominantly expressed in eosinophils. Increased IL-16 expression in UC patients appeared to be mainly restricted to the inflamed regions of the colonic mucosa. Levels of caspase 3, which processes the 68 kDa IL-16 precursor molecule into the biological active 17 kDa form, were not increased. CONCLUSIONS: Our results provide evidence that IL-16 expression is significantly increased in the inflamed colonic mucosa of IBD patients but not in control individuals, DSC, or patients under steroid treatment. Therefore, upregulation of IL-16 expression seems to be specific for chronic intestinal inflammation and could lead to increased secretion of other proinflammatory cytokines in IBD.

Adult↗
PubMed2001

Imaging of striatal dopamine D(2) receptors with a PET system for small laboratory animals in comparison with storage phosphor autoradiography: a validation study with (18)F-(N-methyl)benperidol.

UNLABELLED: Several groups have developed high-resolution PET systems and shown the feasibility of in vivo studies on small laboratory animals. In this investigation, one of these systems was validated for the performance of receptor imaging studies. For this, the radiotracer concentrations obtained in the same animals with PET and with autoradiography were quantified, and the correspondence between both methods was assessed by means of correlation analysis. METHODS: Striatal radioactivity was measured in 10 Sprague-Dawley rats after injection of 60 +/- 10 MBq of the dopamine D(2) receptor ligand (18)F-(N-methyl)benperidol in 6 time frames of 6 min each. On completion of the scans, animals were killed, and their brains were removed and sectioned using a cryostat microtome. Coronal slices were subjected to storage phosphor autoradiography with BaFBr:Eu(2+)-coated imaging plates. Striatal radioactivity was quantified in both modalities using region-of-interest analysis and activity standards. RESULTS: After partial-volume correction, the median of striatal radioactivity concentration measured with PET was 0.40 MBq/cm(3) (25th percentile, 0.32; 75th percentile, 0.44). Radioactivity concentrations determined by means of storage phosphor autoradiography amounted to 0.42 MBq/cm(3) (25th percentile, 0.24; 75th percentile, 0.51). Correlation of striatal radioactivity values yielded a Pearson correlation coefficient of 0.818 (P = 0.002). Radioactivity accumulation in Harder's glands led to an overestimation of striatal activity concentrations by approximately 5%. The median of striatal radioactivity concentration after spillover correction decreased slightly to 0.38 MBq/cm(3) (25th percentile, 0.30; 75th percentile, 0.43). Correlation of striatal radioactivity values after spillover correction yielded a Pearson correlation coefficient of 0.824 (P = 0.002). CONCLUSION: The results show a significant positive correlation between radioactivity values obtained with PET and storage phosphor autoradiography used as the gold standard. Because we applied a selective dopamine D(2) receptor radioligand and because radioactivity concentrations could be reliably quantified in the target region, we may infer that in vivo receptor binding studies will be possible in small laboratory animals.

Animals↗
PubMed2000

Mechanisms in failure of infliximab for Crohn's disease.

BACKGROUND: Expression of tumour necrosis factor-alpha (TNF-alpha) is increased in patients with Crohn's disease. Nuclear factor kappa B (NFkappaB) controls transcription of inflammation genes. Treatment with monoclonal antibodies to TNF (infliximab) in refractory Crohn's disease results in a remission rate of 30-50% after 4 weeks. We aimed to assess the clinical and immunological mechanism of failure to respond to infliximab. METHODS: 24 patients with steroid refractory, chronic active Crohn's disease (Crohn's disease activity index [CDAI]>200), who showed an inflammatory manifestation in the sigmoid colon, had a single infusion of infliximab (5 mg/kg bodyweight) and were followed up for 16 weeks. Secretion capacity for TNF-alpha was assessed in whole-blood cytokine assays and nuclear concentrations of NFkappaB p65 were determined in colonic mucosal biopsy samples. FINDINGS: 21 (88%) of 24 patients were in remission (CDAI<150) after 1 week, ten (42%) at 4 weeks, five (21%) at 8 weeks, and two (8%) of 24 at 12 and 16 weeks. Six (29%) of 21 patients who reached remission in week 1 relapsed at week 4, 13 (62%) at week 8, 17 (81%) at week 12, and 19 (90%) at week 16. Infliximab downregulated secretion of TNF-alpha in all patients to undetectable concentrations (day 1 after infusion). Relapsers were characterised by a rise in TNF-alpha secretion capacity and by increase of mucosal nuclear NFkappaB p65 before reactivation of clinical symptoms. INTERPRETATION: Infliximab greatly improved clinical symptoms in 88% of patients with Crohn's disease after 1 week. Response in some patients was of short duration. Reactivation of the mucosal and the systemic immune system preceded clinical relapse.

Antibodies, Monoclonal↗