Publications by authors named "Ralph Feltens"

In most bacterial type A RNase P RNAs (P RNAs), two major loop-helix tertiary contacts (L8-P4 and L18-P8) help to orient the two independently folding S- and C-domains for concerted recognition of precursor tRNA substrates. Here, we analyze the effects of mutations in these tertiary contacts in P RNAs from three different species: (i) the psychrophilic bacterium (), (ii) the mesophilic radiation-resistant bacterium () and (iii) the thermophilic bacterium (). We show by UV melting experiments that simultaneous disruption of these two interdomain contacts has a stabilizing effect on all three P RNAs.

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Background: Exposure to endocrine-disrupting chemicals can alter normal physiology and increase susceptibility to non-communicable diseases like obesity. Especially the prenatal and early postnatal period is highly vulnerable to adverse effects by environmental exposure, promoting developmental reprogramming by epigenetic alterations. To obtain a deeper insight into the role of prenatal bisphenol A (BPA) exposure in children's overweight development, we combine epidemiological data with experimental models and BPA-dependent DNA methylation changes.

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Background: Prenatal and early postnatal exposures to environmental factors are considered responsible for the increasing prevalence of allergic diseases. Although there is some evidence for allergy-promoting effects in children because of exposure to plasticizers, such as phthalates, findings of previous studies are inconsistent and lack mechanistic information.

Objective: We investigated the effect of maternal phthalate exposure on asthma development in subsequent generations and their underlying mechanisms, including epigenetic alterations.

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Di-(2-ethylhexyl)-phthalate (DEHP), an ubiquitous environmental contaminant, has been shown to cause adverse effects on glucose homeostasis and insulin sensitivity in epidemiological studies, but the underlying mechanisms are still unknown. We therefore tested the hypothesis that chronic DEHP exposure causes impaired insulin sensitivity, affects body weight, adipose tissue (AT) function and circulating metabolic parameters of obesity resistant 129S6 mice in vivo. An obesity-resistant mouse model was chosen to reduce a potential obesity bias of DEHP effects on metabolic parameters and AT function.

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Background: Culicoides biting midges are vectors of bluetongue and Schmallenberg viruses that inflict large-scale disease epidemics in ruminant livestock in Europe. Methods based on morphological characteristics and sequencing of genetic markers are most commonly employed to differentiate Culicoides to species level. Proteomic methods, however, are also increasingly being used as an alternative method of identification.

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In industrialized countries, people spend more time indoors and are therefore increasingly exposed to volatile organic compounds that are emitted at working places and from consumer products, paintings, and furniture, with chlorobenzene (CB) and 1,2-dichlorobenzene (DCB) being representatives of the halogenated arenes. To unravel the molecular effects of low concentrations typical for indoor and occupational exposure, we exposed human lung epithelial cells to CB and DCB and analyzed the effects on the proteome level by 2-D DIGE, where 860 protein spots were detected. A set of 25 and 30 proteins were found to be significantly altered due to exposure to environmentally relevant concentrations of 10(-2) g/m(3) of CB or 10(-3) g/m(3) of DCB (2.

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Purpose: To explore the presence of differentially expressed proteins in OSCC for discrimination of tumour and normal mucosa to establish potential biomarkers and therapeutic targets.

Experimental Design: Paired protein samples of 12 individuals (tongue cancer and non-cancerous mucosa) were separated by two-dimensional polyacrylamid gel electrophoresis. The protein patterns were compared pairwise and protein spots were quantified.

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Background: The use of molecular biology-based methods for species identification and establishing phylogenetic relationships has supplanted traditional methods relying on morphological characteristics. While PCR-based methods are now the commonly accepted gold standards for these types of analysis, relatively high costs, time-consuming assay development or the need for a priori information about species-specific sequences constitute major limitations. In the present study, we explored the possibility to differentiate between 13 different species from the genus Drosophila via a molecular proteomic approach.

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Styrene is a volatile organic compound that is widely used as an intermediate in many industrial settings. There are known adverse health effects at environmentally significant concentrations, but little is known about the molecular effect of exposure to styrene at sub-acute toxic concentrations. We exposed human lung epithelial cells, at a wide range of concentrations (1 mg/m(3)-10 g/m(3)), to styrene and analyzed the effects on the proteome level by 2-DE, where 1380 proteins spots were detected and 266 were identified unambiguously by MS.

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Chlorobenzene is a volatile organic compound (VOC) that is widely used as a solvent, degreasing agent and chemical intermediate in many industrial settings. Occupational studies have shown that acute and chronic exposure to chlorobenzene can cause irritation of the mucosa of the upper respiratory tract and eyes. Using in vitro assays, we have shown in a previous study that human bronchial epithelial cells release inflammatory mediators such as the cytokine monocyte chemoattractant protein-1 (MCP-1) in response to chlorobenzene.

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Conclusion: Changes in the metabolism of arachidonic acid (AA) might be part of a noise-induced compensatory mechanism with regional specificity.

Objectives: The released imbalance of prostaglandins and leukotrienes, both AA metabolites, might result in altered blood flow regulation in the inner ear and probably contributes to noise-induced hearing loss. The aim of this study was to gain further information about noise-dependent changes in AA metabolism in the mammalian cochlea.

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Styrene is a volatile organic compound (VOC) that is widely used as a solvent in many industrial settings. Chronic exposure to styrene can result in irritation of the mucosa of the upper respiratory tract. Contact of styrene with epithelial cells stimulates the expression of a variety of inflammatory mediators, including the chemotactic cytokine monocyte chemoattractant protein-1 (MCP-1).

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Vascular endothelial growth factor (VEGF) is a vascular permeability regulating, proangiogenic factor with neuroprotective properties. Its expression in the inner ear has been demonstrated, but little is known concerning its subcellular distribution or potential involvement in sound perception and adaptation to noise. Therefore, we determined the expression patterns and levels of VEGF and the three VEGF-receptors FLK, FLT and Neuropilin in the cochlea of guinea pigs, and examined the alterations occurring after noise exposure.

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The cyclooxygenase-2 isoform (COX-2) was found recently to be constitutively expressed in the guinea pig inner ear. To gain knowledge about its role in sound perception, alterations in the COX-2 level of moderate noise-stimulated cochleae were determined. Staining intensities were quantified in different regions using an immunohistochemical staining procedure and computer-assisted system.

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Endothelial nitric oxide synthase (eNOS) upregulation was identified 60 h after acute noise trauma in morphologically intact cells of the reticular lamina in the organ of Corti of the guinea pig in the second turn of the cochlea. Using gold-coupled anti-eNOS antibodies and electron microscopy, it was shown that eNOS expression was upregulated in all cell areas and cell types except inner hair cells. Furthermore, eNOS was found in the organelle-free cytoplasm and in mitochondria of various cell types.

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Aim: To characterize gene polymorphism of several cytokine gene in-patients with AIH and PBC and to analyze the difference of the polymorphism distribution between Chinese patients and healthy controls.

Methods: The study population consisted of 62 patients with AIH, and 77 patients with PBC. The genetic profile of four cytokines was analyzed by restriction fragment length polymorphism after specific PCR amplification (PCR-RFLP) or sequence-specific primers PCR (SSP-PCR).

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Background: Autoimmune hepatitis (AIH) and primary biliary cirrhosis (PBC) are two autoimmune diseases of unknown etiology. Genetic factors appear to be involved in the pathogenesis of both diseases. Vitamin D has been shown to exert multiple immunomodulatory effects, which acts through its own receptor (VDR).

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Aim: To investigate the association between Chinese patients with autoimmune hepatitis (AIH), primary biliary cirrhosis (PBC) and the polymorphisms of cytotoxic T lymphocyte-associated antigen-4 (CTLA-4) gene promoter (-318) and exon 1 (+49).

Methods: CTLA-4 promoter (-318 T/C) and exon1 (+49A/G) polymorphisms were genotyped via restriction fragment length polymorphism methods in 62 Chinese AIH patients, 77 Chinese PBC patients and 160 healthy controls.

Results: We found a significant association in CTLA-4 gene exon1 49 A/G polymorphism between PBC patients and controls (P = 0.

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Objective: Autoimmune hepatitis (AIH) and primary biliary cirrhosis (PBC) are two autoimmune diseases of unknown etiology. Genetic factors appear to be involved in the pathogenesis of both diseases. Tumor necrosis factor (TNF)-alpha is one of the proinflammatory cytokines and immunomodulators, and is implicated in the pathogenesis of AIH and PBC.

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Article Synopsis
  • The study aimed to investigate the link between vitamin D receptor (VDR) gene polymorphisms and autoimmune liver diseases, specifically autoimmune hepatitis (AIH) and primary biliary cirrhosis (PBC), in a Chinese population.
  • Using PCR-RELP, researchers analyzed VDR polymorphisms in patients and healthy controls, finding significant differences in VDR gene variants between AIH/PBC patients and healthy individuals.
  • The results indicate that specific VDR polymorphisms, particularly FokI and BsmI, are associated with an increased risk of AIH and PBC in the Chinese population, differing from trends observed in Caucasian groups.
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The RNase P protein gene (rnpA) completely overlaps the rpmH gene (encoding ribosomal protein L34) out of frame in the thermophilic bacterium Thermus thermophilus. This results in the synthesis of an extended RNase P protein (C5) of 163 aa and, by inference, of 240 aa in the related strain Thermus filiformis. Start codons of rnpA and rpmH, apparently governed by the same ribosome binding site, are separated by only 4 nt, which suggests a regulatory linkage between L34 and C5 translation and, accordingly, between ribosome and RNase P biosynthesis.

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Several tRNAs in the hyperthermophilic bacterium Aquifex aeolicus are encoded in clusters and as part of ribosomal RNA operons, implying the requirement for tRNA processing by ribonuclease P (RNase P). Intriguingly, neither a gene for the RNA nor the protein component of this ubiquitous ribonucleoprotein enzyme has been hitherto identified in the sequenced genome of A. aeolicus, despite extensive data mining.

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We have detected by nucleotide analog interference mapping (NAIM) AMPalphaS and IMPalphaS modifications in Bacillus subtilis RNase P RNA that interfere with binding of the homologous protein subunit. Interference as well as some enhancement effects were clustered in two main areas, in P10.1a/L10.

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