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Biomedical subjects

S Wendt

Publications and source records attributed to S Wendt.

At least 19 recordsLinked to original sources
PubMed2007

Enzyme replacement therapy with agalsidase alfa in children with Fabry disease.

AIM: To assess the effects of enzyme replacement therapy (ERT) in children with Fabry disease. METHODS: Safety and efficacy of ERT with agalsidase alfa, 0.2 mg/kg infused over 40 minutes every 2 weeks for 23 weeks, were studied in a multicentre open-label trial in nine boys and four girls. Median age at the start of the study was 11.0 years (range 3.5-18 years). RESULTS: Fifty-four adverse events were reported in 11 patients. No serious adverse events related to ERT were reported. Twelve of the 54 adverse events were considered possibly or probably related to ERT. Infusion reactions (8 mild, 3 moderate) occurred in four boys, in seven infusions. One boy developed IgG antibodies, although he continued to make good clinical progress. At the end of the study, two of the four boys and the one girl on regular pain medication at baseline had stopped taking analgesics. Brief Pain Inventory (BPI) scores decreased in most patients by week 12 and were sustained until the end of the study. This change was greater in the boys, who had higher (worse) BPI scores at baseline. Pain-related quality of life (QoL) scores also decreased during the study. Plasma globotriaosylceramide concentrations and urinary globotriaosylceramide:sphingomyelin ratios decreased after 12 and 23 weeks of therapy, particularly in the boys. Increases in sweat volume were recorded in three out of five of the boys and in one of two girls tested after 23 weeks of treatment. CONCLUSION: ERT with agalsidase alfa in children with Fabry disease is well tolerated and, in the short term, appears to decrease pain and to improve pain-related QoL.

Adolescent↗
PubMed2006

Formation and splitting of paired hydroxyl groups on reduced TiO2(110).

A combination of high-resolution scanning tunneling microscopy and density functional theory is utilized to study the interaction of water with the reduced TiO2(110)-(1 x 1) surface. As the direct product of water dissociation in oxygen vacancies, paired hydroxyl groups are formed. These pairs are immobile and stable unless they interact with adsorbed water molecules. As a result of these interactions, protons are transferred to adjacent oxygen rows, thereby forming single hydroxyl groups. Additionally, we show that hydroxyl groups facilitate the diffusion of water molecules over the oxygen rows.

Journal Article↗
PubMed2005

Susceptibility of different eukaryotic cell lines to SARS-coronavirus.

In order to define and characterize target cells of SARS-coronavirus (SARS-CoV) we studied the susceptibility of 23 different permanent and primary eukaryotic cell lines to SARS-coronavirus. Beneath Vero E6 cells SARS- Coronavirus infection could also be demonstrated in two pig cell lines (POEK, PS) and one human cell line (Huh-7) using the indirect immunofluorescence assay and a newly established quantitative real-time PCR. In all susceptible cell lines mRNA of the Angiotensin-converting enzyme 2 (ACE2), the functional receptor for SARS-CoV infection, could be detected by RT-PCR. Our results show that there is a correlation between the abundance of ACE2 mRNA and SARS-CoV susceptibility.

Angiotensin-Converting Enzyme 2↗
PubMed2001

The influence of stocking rate on transmission of helminth parasites in pigs on permanent pasture during two consecutive summers.

This study was made to elucidate the transmission of nematode infections in outdoor pigs at different stocking rates during two consecutive seasons. Five pigs (Group 1A) inoculated with low doses of Oesophagostomum dentatum, Ascaris suum, and Trichuris suis and five helminth-naïve pigs (Group 1B) were turned out together in June 1996 on each of four pastures at stocking rates of 100, 240 (two pastures) and 576m(2) per pig, respectively. The pigs were slaughtered in early October, and pasture infectivity was subsequently measured using helminth-naïve tracer pigs (Tracer). In 1997, 10 helminth-naïve pigs were turned out on each pasture in May (Group 2) and again in August (Group 3), and allowed to graze for 12 weeks. The percentage of grass cover was reduced considerably at the high stocking rate in comparison to the other stocking rates. Transmission of all three helminths was observed on all pastures. In 1996, the O. dentatum faecal egg counts and worm burdens were significantly higher in pigs at the high stocking rate compared to pigs at the other stocking rates. O. dentatum did not survive the winter and pigs of Group 2 were inoculated with 3000 larvae each to reintroduce this parasite. Ascaris suum ELISA values and worm counts were highest at the high stocking rate in 1997 (Group 3). Transmission of T. suis was not significantly influenced by stocking rate. The results indicate that transmission of O. dentatum, and to some extent A. suum is influenced by stocking rate. However, both A. suum and T. suis eggs are still expected to constitute a high risk of infection on intensively used pastures where eggs may accumulate for years. The relationship between host density and helminth transmission seems more complex for grazing/rooting pigs than for grazing ruminants. This may be due to the differences in behaviour of the animals and the resulting differences in microclimate of the developing eggs/larvae.

Animal Husbandry↗
PubMed2001

Retinal pigment epithelium melanin granules are phagocytozed by Müller glial cells in experimental retinal detachment.

The ability of retinal Müller glial cells to perform phagocytosis in vivo is studied in a rabbit model of experimental retinal detachment where pigment epithelial cells are occasionally detached together with the neural retina. While macrophages and/or microglial cells phagocytoze most of the cellular debris at the sclerad surface of the detached retinae, some Müller cells accumulate melanin granules. The granules are virtually intact at the ultrastructural level, and are surrounded by a membrane. They are often located close to the sclerad end of the cells, but some are distributed throughout the outer stem process up to the soma. It is concluded that rabbit Müller cells in vivo are capable of phagocytosis and of transporting the phagocytozed material within their cytoplasm.

Animals↗
PubMed2001

[Restructuring of the specialized job market for people with disabilities through legislative reform of the Rehabilitation Act--consequences for the workshops for the disabled].

The legal basis for employment of people with disabilities in sheltered Workshops for the Disabled (Werkstätten für Behinderte, WfB) had hitherto been shaped by the 1961 Federal Social Assistance Act, the 1969 Employment Promotion Act, the 1974 Severely Disabled Persons Act with the related Workshop Ordinances of 1980 and 1996. The Act on Combating Unemployment of Severely Disabled Persons, effective as of Oct. 1, 2000 has now created a new legal foundation, which also is aimed at enhancing Workshop employees' horizontal mobility into the general job market, inter alia providing for access to Supported Employment arrangements and for availability of selective placement and support services (Integrationsfachdienste, IFD) throughout Germany. These Services also are intended as points of contact in the counselling of severely disabled school leavers in relation to placement opportunities in competitive jobs and/or integration projects or firms. Discussed from a legal perspective are the differences in sociolegal respects between such projects for severely disabled persons and employment in Workshops for the Disabled, as well as implications for the Workshops' own economic activity, also making reference to the forthcoming Book 9 of the Social Code.

Persons with Disabilities↗
PubMed2001

Facilitation of artificial retinal detachment for macular translocation surgery tested in rabbit.

PURPOSE: For macular translocation surgery, the native attached retina has to be detached either locally or completely. Although different surgical techniques are used, there is a general search for supporting procedures that facilitate and accelerate the retinal detachment. METHODS: Pars plana vitrectomies were performed in pigmented rabbits. In all experimental groups, a local retinal detachment was created by infusing the test solution with a thin glass micropipette attached to a glass syringe. In control animals a standard balanced salt solution was used at room temperature, in combination with a standard vitrectomy light source. In two test groups, a calcium- and magnesium-free solution was used for the vitrectomy, under illumination by a standard light source in group I (solution at room temperature) and group II (solution heated up to body temperature). In group III the rabbits were dark-adapted for half an hour, and then, during surgery, a red filter was used in front of the light source (standard balanced salt solution at room temperature). After the rabbits were killed at the end of surgery, the adherence of the retinal pigment epithelium (RPE) to the neural retina in the detachment area was quantified microscopically, and the morphologic integrity of the detached retinal tissue was examined by light and electron microscopy. No electrophysiology was performed. RESULTS: In all four groups, it was possible to detach the retina. The maximum adherence of the RPE cells to the neural retina was observed in the control group. Virtually no decrease in adherence was found in test group II (36 degrees C solution without calcium and magnesium), whereas a significant decrease was seen in both group I (calcium- and magnesium-free solution at room temperature) and group III (dark adaptation-red light technique; standard balanced salt solution at room temperature). In none of the experimental groups was any obvious damage of the retinal structure observed, even after exposure to the test solutions for 60 minutes. CONCLUSIONS: Both dark adaptation (red illumination) and the use of a calcium chloride- and magnesium chloride-free solution (at room temperature) can facilitate retinal detachment in macular translocation surgery. Both techniques are proposed as a gentle support for the operation, because they protect an intact RPE cell layer and do not cause retinal damage at the ultrastructural level.

Animals↗
PubMed2000

Atomic-scale structure and catalytic reactivity of the RuO(2)(110) surface

The structure of RuO(2)(110) and the mechanism for catalytic carbon monoxide oxidation on this surface were studied by low-energy electron diffraction, scanning tunneling microscopy, and density-functional calculations. The RuO(2)(110) surface exposes bridging oxygen atoms and ruthenium atoms not capped by oxygen. The latter act as coordinatively unsaturated sites-a hypothesis introduced long ago to account for the catalytic activity of oxide surfaces-onto which carbon monoxide can chemisorb and from where it can react with neighboring lattice-oxygen to carbon dioxide. Under steady-state conditions, the consumed lattice-oxygen is continuously restored by oxygen uptake from the gas phase. The results provide atomic-scale verification of a general mechanism originally proposed by Mars and van Krevelen in 1954 and are likely to be of general relevance for the mechanism of catalytic reactions at oxide surfaces.

Journal Article↗
PubMed2000

Nose-rings and transmission of helminth parasites in outdoor pigs.

Five growing pigs experimentally infected with low doses of Oesophagostomum dentatum, Ascaris suum, and Trichuris suis were turned out with 5 helminth-naïve pigs on each of 3 pastures in June 1996 (Group 1). On one pasture all pigs received nose-rings. After slaughter of Group 1 in October, pasture infectivity was monitored using helminth-naïve, unringed tracer pigs. In 1997, helminth-naïve young pigs were turned out on the contaminated pastures in May (Group 2) and again in August (Group 3). Again all pigs on one pasture received nose-rings. All pigs and pastures were followed parasitologically and reduction in grass cover was monitored. Based on the acquisition of infection by the naïve pigs in Group 1, the estimated minimal embryonation times for eggs deposited on pasture were 23-25 days for O. dentatum, 5-6 weeks for A. suum and 9-10 weeks for T. suis. Results from tracer pigs and grass/soil samples indicated that pasture infectivity was light both years. Free-living stages of O. dentatum did not survive the winter. The nose-rings reduced rooting considerably, resulting in three-fold more grass cover on the nose-ring pasture compared to the control pastures by the end of the experiment. Nevertheless, the nose-rings did not significantly influence parasite transmission.

Animals↗
PubMed1999

Free radical-induced inactivation of creatine kinase: influence on the octameric and dimeric states of the mitochondrial enzyme (Mib-CK).

Free radicals of X-ray-induced water radiolysis, either directly or indirectly via their reaction products, reduce the activity of both dimeric cytoplasmic muscle-type creatine kinase (MM-CK) and octameric mitochondrial creatine kinase (Mi-CK) to virtually zero. Similarly values of the characteristic D(37)-dose of enzyme inactivation (dose required to reduce enzyme activity to 37%) were found for the two isoenzymes of CK under identical conditions. Octamer stability was not significantly affected within the dose range considered. However, both the dissociation of octamers into dimers by a transition-state analogue complex (TSAC), and the reassociation of the dimers into octamers, showed dose-dependent reduction. Binding of the TSAC to the active centre was found to protect the enzyme against inactivation by free radicals. No protection was observed for the radiation-induced decrease of the endogenous tryptophan fluorescence. The experimental results are in line with the following interpretation: (i) the reduction of Mi(b)-CK dimer association is due to free radical-induced modification of Trp-264, situated at the dimer/dimer interface; (ii) the active-site Trp-223 is not a prime target for free radicals and is not involved in the inactivation of the enzyme; (iii) the inhibition of TSAC-induced dissociation of Mi(b)-CK, like enzyme inactivation, is primarily due to a modification of the active-site Cys-278.

Animals↗
PubMed1999

Octamer-dimer transitions of mitochondrial creatine kinase in heart disease.

Mitochondrial creatine kinase (Mi-CK) occurs in dimeric and octameric forms, both in vitro and in vivo. The Mi-CK octamer, however, is the predominant form in vivo and is important for various functions of the protein. In the present study we show for the first time a significant decrease of the octamer/dimer ratio in vivo, related to ischemia-induced damage, and a similar decrease of octamer stability in vitro, induced by peroxynitrite (PN) radicals. We used animal models to induce ischemia in two different ways: acute ischemia in intact heart (Langendorff perfusion) and chronic ischemia in vivo (LAD-infarction). In both models, impairment of heart function and mitochondrial energy metabolism was associated with a significant decrease of Mi-CK octamer/dimer ratios and of Mi-CK activities. These findings, together with recent data showing that the formation of PN is induced in ischemia and that Mi-CK is a prime target of peroxynitrite (PN)-induced damage, suggest that oxygen radicals generated during ischemia and reoxygenation could be an important factor for the decreased octamer stability. To test this hypothesis, we studied the effect of PN on pure Mi-CK in vitro, both on dissociation of octamers and reassociation of dimers. At 1 m m PN 66% of Mi-CK octamers dissociated into dimers, whereas octamerization of PN-modified dimers was already completely inhibited at 100 microm PN. Our data indicate that PN-induced damage could be responsible for the octamer-dimer transition of Mi-CK in ischemia. A loss of Mi-CK octamers would impair the channeling of high energy phosphate out of mitochondria and hence heart function in general.

Animals↗
PubMed1998

Mass spectrometric mapping of ion channel proteins (porins) and identification of their supramolecular membrane assembly.

Mass spectrometric peptide mapping, particularly by matrix-assisted laser desorption-ionization (MALDI-MS), has recently been shown to be an efficient tool for the primary structure characterization of proteins. In combination with in situ proteolytic digestion of proteins separated by one- and two-dimensional sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), mass spectrometric peptide mapping permits identification of proteins from complex mixtures such as cell lysates. In this study we have investigated several ion channel membrane proteins (porins) and their supramolecular assembly in mitochondrial membranes by peptide mapping in solution and upon digestion in the gel matrix. Porins are integral membrane proteins serving as nonspecific diffusion pores or as specific systems for the transport of substrates through bacterial and mitochondrial membranes. The well-characterized porin from Rhodobacter capsulatus (R.c.-porin) has been found to be a native trimeric complex by the crystal structure and was used as a model system in this study. R.c.-porin was characterized by MALDI-MS peptide mapping in solution, and by direct in situ-gel digestion of the trimer. Furthermore, in this study we demonstrate the direct identification of the noncovalent complex between a mitochondrial porin and the adenine nucleotide translocator from rat liver, by MALDI-MS determination of the specific peptides due to both protein sequences in the SDS-PAGE gel band. The combination of native gel electrophoresis and mass spectrometric peptide mapping of the specific gel bands should be developed as a powerful tool for the molecular identification of protein interactions.

Electrophoresis, Polyacrylamide Gel↗
PubMed1991

Imipenem resistance in Acinetobacter baumanii is due to altered penicillin-binding proteins.

The comparison of a clinical Acinetobacter baumanii isolate (strain No. 4852/88) and its selected imipenem-resistant (IMR) clone exhibited a complex reorganization of the penicillin-binding proteins (PBPs) with diminished labelling of all PBPs except the 24-kD PBP which showed an increased binding of 14C-penicillin. This protein could not be saturated by preincubation of membranes with imipenem at 8-fold the MIC of imipenem, thus indicating PBP alterations responsible for imipenem resistance. In A. baumanii 4852/88 seven PBPs with the apparent molecular weights of 94, 84, 65, 61, 48, 40 and 24 kD could be detected. beta-Lactamase production was barely detectable in any case and could not be enhanced in the presence of various beta-lactams as the inducer. The outer membrane proteins were found identical in both the wild-type strain and the Im clone. So far, imipenem-resistant A. baumanii isolates have been isolated twice in our diagnostic laboratory; however, no implications on the future relevance of the above findings can be made.

Acinetobacter↗