Biomedical subjects

Bernd Müller

Publications and source records attributed to Bernd Müller.

13 recordsLinked to original sources

PubMed2005

NO2-induced acute and chronic lung injury cause imbalance of glutathione metabolism in type II pneumocytes.

BACKGROUND: During inspiration the lung is exposed to numerous oxidants and therefore has developed a system of antioxidant defense. This organ, besides the liver, is the major source of glutathione (GSH) metabolism, from which type II pneumocytes are metabolically the most active cells. MATERIAL/METHODS: To analyze oxidative stress, rats were exposed to air (control) or to 10 ppm nitrogen dioxide (NO2) for 3 and 20 days to induce acute and chronic lung injury. As measure of oxidative stress, GSH/GSSG ratios in blood, bronchoalveolar lavage (BAL) and type II pneumocytes were determined. Lipid peroxidation (LPO) was also measured in type II cells. To investigate the basis of these observations, GSH metabolism in type II pneumocytes was studied, analyzing mRNA expression of gamma-glutamyl-cysteine synthetase (gamma-GCS), glutathione synthetase (GS), gamma-glutamyltranspeptidase (gamma-GT), glutathione peroxidases (GPXs) and glutathione reductase (GR). Furthermore, enzyme activities of GPX and GR were determined. RESULTS: In acute and chronic lung injury the GSH/GSSG ratio was reduced in blood and BAL, but there was no change in type II pneumocytes. LPO in type II cells was only reduced in acute lung injury. In both kinds of lung injury mRNA expression of gamma-GCS, GS and GPX3 decreased, while expression of gamma-GT and GR increased. GPX4 mRNA expression decreased in acute lung injury and increased in the chronic state. Enzyme activity of GPX and GR was generally increased in lung injury. CONCLUSIONS: In NO2 induced acute and chronic lung injury, GSH metabolism is imbalanced.

Acute Disease↗

PubMed2005

Interactions of poly(vinylpyrrolidone) with ibuprofen and naproxen: experimental and modeling studies.

PURPOSE: To elucidate the differences in the interaction of chiralic ibuprofen (IBP) and naproxen (NAP) with poly(vinylpyrrolidone) (PVP) in a solid state. METHODS: Drugs/PVP physical mixtures and solid dispersions were characterized by scanning electron microscope (SEM), Fourier transform infrared spectrometry (FT-IR), solid state (13)C NMR spectroscopy, and x-ray diffractometry. Molecular modeling study of the crystal structures and PVP was performed. RESULTS: A spontaneous conversion of IBP/PVP physical mixtures in a stable glasslike form (solid dispersion) was observed after storage. The enantiomer reacted more strongly than the racemate. NAP did not interact with PVP. The crystal structures of drugs showed differences in the hydrogen bonding, aromatic interactions, molecular energies, and distances inside the crystals. The trimer structure of PVP was built and optimized. It was proposed that each PVP monomer could interact with one IBP dimmer in contrast to NAP, where two out of three PVP monomers faced the catemer carboxylic groups. CONCLUSIONS: The differences in the interaction of PVP with racemic IBP, enantiomer IBP, and NAP can be related to the differences in their crystal structures. The correlation between the experimental data and the results of the molecular modeling analysis suggest that the IBP dimmer structures are likely to perform HB and aromatic interactions with PVP.

Calorimetry, Differential Scanning↗

PubMed2005

Cell-specific modulation of surfactant proteins by ambroxol treatment.

Ambroxol [trans-4-(2-amino-3,5-dibromobenzylamino)-cyclohexanole hydrochloride], a mucolytic agent, was postulated to provide surfactant stimulatory properties and was previously used to prevent surfactant deficiency. Currently, the underlying mechanisms are not exactly clear. Because surfactant homeostasis is regulated by surfactant-specific proteins (SP), we analyzed protein amount and mRNA expression in whole lung tissue, isolated type II pneumocytes and bronchoalveolar lavage of Sprague-Dawley rats treated with ambroxol i.p. (75 mg/kg body weight, twice a day [every 12 h]). The methods used included competitive polymerase chain reaction (RT-PCR), Northern blotting, Western immunoblotting, and immunohistochemistry. In isolated type II pneumocytes of ambroxol-treated animals, SP-C protein and mRNA content were increased, whereas SP-A, -B and -D protein, mRNA, and immunoreactivity remained unaffected. However, ambroxol treatment resulted in a significant increase of SP-B and in a decrease of SP-D in whole lung tissue with enhanced immunostaining for SP-B in Clara Cells. SP-A and SP-D were significantly decreased in BAL fluid of ambroxol-treated animals. The data suggest that surfactant protein expression is modulated in a cell-specific manner by ambroxol, as type II pneumocytes exhibited an increase in SP-C, whereas Clara cells exhibited an increase in the immunoreactivity for SP-B accounting for the increased SP-B content of whole lung tissue. The results indicate that ambroxol may exert its positive effects, observed in the treatment of diseases related to surfactant deficiency, via modulation of surfactant protein expression.

Ambroxol↗

PubMed2004

Impaired superoxide radical production by bronchoalveolar lavage cells from NO(2)-exposed rats.

Production of superoxide radicals is a central property of professional phagocytes used to combat invading microorganisms. Even though the number of macrophages and neutrophils is often increased in the lungs of patients with chronic lung diseases, these patients frequently suffer from bacterially induced exacerbations. To understand the underlying mechanisms, we investigated the production of superoxide radicals by bronchoalveolar lavage (BAL) cells in a rat NO(2) exposure model (10 ppm NO(2) for 1, 3, or 20 days). We showed that cells from NO(2)-exposed animals display a significantly impaired superoxide radical release after zymosan stimulation. The use of specific inhibitors (antimycin or diphenyleneiodonium [DPI]) revealed that the major enzyme systems, NADPH oxidase and complex III of the respiratory chain, are affected. In addition, we investigated gene expression and enzyme activities of antioxidant enzymes. mRNA expression was significantly enhanced for glutathione peroxidase (GPx)-3 and CuZn-superoxide dismutase (SOD) in BAL cells from animals exposed 3 and 20 days, and GPx and SOD enzyme activities were increased in BAL cells from rats exposed 20 days. In conclusion, concomitant occurrence of reduced production and increased scavenging of superoxide radicals resulted in the drastically impaired release of these radicals from BAL cells of NO(2)-exposed rats.

Animals↗

PubMed2004

Upregulation of the CLIP self peptide on mature dendritic cells antagonizes T helper type 1 polarization.

Dendritic cells (DCs) initiate and regulate immunity against foreign and self antigens. Here we identified more than 200 individual major histocompatibility complex class II-associated peptides on human DCs and found that mature DCs selectively upregulated the self peptide CLIP. CLIP cosegregated together with foreign antigenic peptides in tetraspan microdomains on the surface and localized to DC-T cell synapses. The increased representation of CLIP-major histocompatibility complex class II complexes favored polarization of autologous naive T cells toward the nonpolarized and T helper type 2 (T(H)2) phenotype. There was also a considerably higher T(H)2/T(H)1 ratio in H2-DM-deficient mice, which have a CLIP(hi) phenotype, in contrast to wild-type, CLIP(lo) mice. Thus, the self peptide CLIP on DCs qualifies as an endogenous regulator in priming of T helper cells by antagonizing the polarization toward the T(H)1 phenotype.

Antigen Presentation↗

PubMed2004

The angle between the Frankfort horizontal and the sella-nasion line. Changes in porion and orbitale position during growth.

AIM: The starting point of this study was the statement made in the literature that the angle between the two reference planes Frankfort horizontal (FH) and sella-nasion line (SN) changes relatively little during growth. The growth-induced relocation of the orbitale (Or; anterior reference point of the FH) in relation to SN is known from implant studies, whereas the relocation of the porion (Po; posterior reference point of the FH) has been the subject of only little research. The present study was aimed at analyzing the factors contributing to the almost constant angle between FH and SN. MATERIAL AND METHOD: The study material consisted of two groups of macerated skulls and the relevant lateral cephalograms. The first group comprised 32 skulls of individuals aged 2.5 to 5 years, and the second group ten skulls of individuals aged 18 to 20 years. A diagram showing the growth-dependent changes was prepared with reference to the mean values for the two groups. The cephalograms were superimposed on the anterior cranial base line at sella point (S). RESULTS: A 3.1 degrees increase in the angle between FH and SN during growth was recorded in our investigations. The distance between Or and SN increased by 3.9 mm while Po remained vertically almost constant with respect to SN. In sagittal direction the distance between Or and S also increased, while Po was displaced to almost the same extent in the opposite direction. The increasing vertical distance between the anterior and posterior reference points of FH and SN was largely compensated by the sagittal developments of the reference points Po and Or, so that the angle between these two planes changed very little. The relatively stable angle between FH and SN thus showed by no means a constant relationship of the four reference points to one another.

Adolescent↗

PubMed2003

Comparison of linear measurements in cephalometric studies.

Five longitudinal cephalometric studies were evaluated with regard to discrepancies in their methodology. The roentgenographic enlargement was determined for each study separately. One linear cephalometric distance was then depicted graphically with and without correction for enlargement. This revealed that, besides other inaccuracies in the method, it was primarily the neglecting of radiographic enlargement that created considerable distortion of linear dimensions. Growth velocity curves were computed for three selected dimensions and graphically depicted. The determination of a growth spurt according to accepted definitions was impossible in these growth velocity curves. Problems arising in the determination of a growth spurt are discussed.

Adolescent↗

PubMed2003

Glial-neuronal interactions following kainate injection in rats.

Limbic seizures were induced in rats by intraperitoneal injection of the glutamate receptor agonist kainic acid, followed, 24h later by injection of [1-13C]glucose and [1,2-13C]acetate. Analyses of forebrain extracts were performed using 13C magnetic resonance spectroscopy and HPLC. A significant increase in label derived from [1,2-13C]acetate was observed in glutamine and glutamate. Label in most metabolites derived from [1-13C]glucose was unchanged, however, a decrease was observed in [2-13C]GABA, possibly due to reduced GABA release, 24h after kainic acid injection. It should be noted that only astrocytes are able to utilize acetate as a substrate efficiently, whereas acetyl CoA derived from glucose is metabolized predominantly in the neuronal tricarboxylic acid cycle. No significant differences were found in total amounts of amino acids between the two groups. Thus, these results indicate that turnover of metabolites was increased predominantly in astrocytes whereas glutamatergic neurons were not affected. Previous results obtained using the same model [Neurosci. Lett. 279 (2000) 169] showed an increased turnover in both glutamatergic and GABAergic neurons 2 weeks after kainic acid injection. Combining the results from the two studies, it can be suggested that increased astrocytic activity 1 day after epileptic seizures results, subsequently, in an increased amino acid turnover in neurons.

Acetates↗

PubMed2003

Shift toward an alternatively activated macrophage response in lungs of NO2-exposed rats.

Inflammatory mechanisms are thought to play an important role in the pathogenesis of acute and chronic obstructive pulmonary diseases. In a rat inhalation model using continuous exposure to 10 ppm nitrogen dioxide for 1, 3, and 20 d, we investigated the inflammatory response with particular focus on the activation state of alveolar macrophages. Whereas the number of inflammatory cells and total protein concentration were increased in the bronchoalveolar lavage (BAL), the amount of the proinflammatory cytokine tumor necrosis factor-alpha was markedly reduced with increasing exposure time. In contrast, interleukin (IL)-10 and IL-6 were found at elevated levels and intracellular amounts of suppressor of cytokine signaling-3 protein increased in BAL cells. Upon in vitro lipopolysaccharide stimulation, BAL cells revealed reduced capability to produce the proinflammatory mediators tumor necrosis factor-alpha, IL-1 beta, and nitric oxide, but showed markedly increased transcription and protein release for IL-10. In addition, elevated levels of IL-6, scavenger receptor B, and suppressor of cytokine signaling-3 mRNA were detected in BAL cells from exposed animals. Analyses of highly purified alveolar macrophages indicated that changes in the activation state of these cells were responsible for the observed effects. In conclusion, a priming toward development of the alternatively activated macrophage phenotype occurred in the lungs of rats following nitrogen dioxide inhalation.

Administration, Inhalation↗

PubMed2002

The HCF136 protein is essential for assembly of the photosystem II reaction center in Arabidopsis thaliana.

Hcf136 encodes a hydrophilic protein localized in the lumen of stroma thylakoids. Its mutational inactivation in Arabidopsis thaliana results in a photosystem II (PHII)-less phenotype. Under standard illumination, PSII is not detectable and the amount of photosystem I (PSI) is reduced, which implies that HCF136p may be required for photosystem biogenesis in general. However, at low light, a comparison of mutants with defects in PSII, PSI, and the cytochrome b(6)f complex reveals that HCF136p regulates selectively biogenesis of PSII. We demonstrate by in vivo radiolabeling of hcf136 that biogenesis of the reaction center (RC) of PSII is blocked. Gel blot analysis and affinity chromatography of solubilized thylakoid membranes suggest that HCF136p associates with a PSII precomplex containing at least D2 and cytochrome b(559). We conclude that HCF136p is essential for assembly of the RC of PSII and discuss its function as a chaperone-like assembly factor.

Arabidopsis↗

PubMed2002

Differences in mRNA expression, protein content, and enzyme activity of superoxide dismutases in type II pneumocytes of acute and chronic lung injury.

The lung is protected against oxidative stress by a variety of antioxidants and type II pneumocytes seem to play an important role in antioxidant defense. Previous studies have shown that inhalation of NO2 results in acute and chronic lung injury. How the expression and enzyme activity of antioxidant enzymes are influenced in type II cells of different inflammatory stages has yet not been studied. To elucidate this question, we exposed rats to 10 ppm NO2 for 3 or 20 days to induce acute or chronic lung injury. From these and air-breathing rats, type II pneumocytes were isolated. The mRNA expression and protein content of CuZnSOD and MnSOD as well as total SOD-specific enzyme activity were determined. For the acute lung injury (3 d NO2), the expression of CuZnSOD mRNA was significantly increased, while MnSOD expression was significantly reduced after 3 days of NO2 exposure. For the chronic lung injury (20 d NO2), CuZnSOD expression was still enhanced, while MnSOD expression was comparable to control. In parallel to CuZnSOD mRNA expression, the protein amount was significantly increased in acute and chronic lung injury however MnSOD protein content exhibited no intergroup differences. Total SOD enzyme activity showed a significant decrease after 3 days of NO2 exposure and was similar to control after 20 days. We conclude that during acute and chronic lung injury in type II pneumocytes expression and protein synthesis of CuZnSOD and MnSOD are regulated differently.

Animals↗

PubMed2002

Surfactant protein B intron 4 variation in German patients with COPD and acute respiratory failure.

Chronic obstructive pulmonary disease (COPD) is a major health problem. Genetic factors that contribute to the disease have been postulated. The pulmonary surfactant protein B (SP-B), which is essential for normal lung function, is considered as a candidate gene for COPD in this case-control study. We studied the SP-B intron 4 size variants in 346 individuals. This group consisted of 118 patients with chronic bronchitis or COPD, including 24 patients with acute respiratory failure (ARF) in COPD, 118 matched controls without pulmonary disease and 110 healthy individuals (population control). The frequency of intron 4 variants was similar in either control group (10.9%, 14.4%, respectively), with a small increase in the COPD group (18.6%). This increase was due to a high increase of intron 4 variants in the ARF subgroup (37.5%, p = 0.003, OR 4.9, 95% CI: 1.76-13.6). The data indicate that SP-B intron 4 variants may associate with increased risk of ARF in COPD and may be used as a marker of susceptibility in this disease subgroup.

Acute Disease↗

PubMedDate not supplied

Mining knowledge for HEp-2 cell image classification.

HEp-2 cells are used for the identification of antinuclear autoantibodies (ANAs). They allow for recognition of over 30 different nuclear and cytoplasmic patterns, which are given by upwards of 100 different autoantibodies. The identification of the patterns has recently been done manually by a human inspecting the slides with a microscope. In this paper, we present results on the analysis and classification of cells using image analysis and data mining techniques. Starting from a knowledge acquisition process with a human operator, we developed an image analysis and feature extraction algorithm. The collection of the dataset was done based on an expert's image reading and based on the automatic extracted features. A dataset containing 132 features for each entry was set up and given to a data mining algorithm to find out the relevant features among this large feature set and to construct the classification knowledge. The classifier was evaluated by cross validation. The results gave the expert new insights into the necessary features and the classification knowledge and show the feasibility of an automated inspection system.

Algorithms↗