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Biomedical subjects

Gerhard Schwarz

Publications and source records attributed to Gerhard Schwarz.

7 recordsLinked to original sources
PubMed2003

DHPLC scoring of a SNP between promoter sequences of HMW glutenin x-type alleles at the Glu-D1 locus in wheat.

The promoter regions of HMW glutenin x-type genes at the Glu-D1 locus were surveyed for SNPs within a subpopulation of German bread wheat cultivars. On the basis of the promoter sequences of HMW glutenin subunit genes Glu-A1-x1, Glu-A1-x2, Glu-B1-x1, Glu-B1-x7, Glu-D1-x2, and Glu-D1-x5, an amplification refractory mutation system assay was designed to selectively amplify Dx-specific PCR fragments. Comparative sequence analysis among seven Glu-D1-x2 and seven Glu-D1-x5 wheat cultivars only confirmed a G-A transition in the promoter sequence to be a true polymorphism. SNP scoring by DHPLC of 95 German bread wheat cultivars, with the exception of cv. Anemos, showed that the transition completely agreed with the presence of HMW glutenin subunits 1Dx5 + 1Dy10 in SDS-PAGE. Therefore, the developed DHPLC assay is suitable for high-throughput genotyping to assist the selection of HMW glutenin genes in wheat quality breeding programs.

Alleles↗
PubMed2003

Evaluation of Erysiphe graminis f sp tritici field isolates for resistance to strobilurin fungicides with different SNP detection systems.

A single nucleotide polymorphism (snp) in the cytochrome b gene confers resistance to strobilurin fungicides in Erysiphe graminis DC fsp tritici Marchal. On the basis of this point mutation three different types of molecular markers have been developed. Cleaved amplified polymorphic sequences and allele-specific PCR were used to score resistant and sensitive isolates from specifically selected regional populations across Europe. The results of molecular tests were in total agreement with the resistance phenotypes revealed by in vivo tests. Serial dilutions of mixed samples (resistant/sensitive) delimited the detection for strobilurin-resistant alleles to a range of 10-50% for both marker classes. Due to these detection limits no mixture of mitochondria within individual isolates was found. Denaturing high performance chromatography was used to increase the detection sensitivity for the mutant allele. Although the detection limit was lowered to 5-10%, there was no evidence for the existence of mixed mitochondrial genotypes.

Drug Resistance, Fungal↗
PubMed2003

On translocation through a membrane channel via an internal binding site: kinetics and voltage dependence.

Here we present a model for maltodextrin translocation through maltoporin channels. In a first step, our theoretical analysis does consider the case of a single binding site for a given substrate in a structurally unaffected channel with a possibly different entrance barrier on either side. It is shown how by means of conventional electrical conductance measurements (including current noise analysis) the basic equilibrium and rate constants can be determined as functions of the applied voltage. Then also the net translocation rate of the substrate becomes accessible quantitatively. This most simple model mechanism has been extended to include a voltage-dependent fast conformational change of the channel that prevents the binding process. The so developed approach has been tested with experimental data for a single maltoporin trimer being reconstituted in black lipid membranes when studied in the presence of maltohexaose as the substrate. The experimental results turned out to be clearly incompatible with binding alone. They are, however, very satisfactorily fitted by pertinent theoretical curves if also inhibition of binding by a conformational transition is taken into account. Accordingly, quantitative evaluations of the underlying parameters and eventually of the translocation rate have been carried out successfully. Our analysis reveals a set of parameters necessary for an optimal translocation that nicely corresponds to natural conditions.

Bacterial Outer Membrane Proteins↗
PubMed2003

Proinflammatory role of fractalkine (CX3CL1) in rheumatoid arthritis.

OBJECTIVE: Fractalkine (CX3CL1) represents the sole member of the so-called CX3C chemokines. In rheumatoid arthritis (RA), functional studies suggest a role for this chemokine in monocyte chemotaxis and angiogenesis in the rheumatoid synovium. We analyzed the expression of fractalkine within different T cell subsets of the peripheral blood and expression of its receptor CX3CR1 within the rheumatoid synovium to further characterize its pathogenic role in RA. METHODS: Peripheral blood mononuclear cells (PBMC) were isolated from 17 patients with RA and analyzed by flow cytometry in comparison to healthy blood donors. To identify the T helper cell cytokine profile of fractalkine-expressing cells, flow cytometric analysis of PBMC was performed after stimulation with PMA and ionomycin. Expression of fractalkine and its receptor was characterized in RA synovium by immunohistochemistry and laser capture microdissection microscopy. RESULTS: Flow cytometric analysis of fractalkine-expressing T cell subsets revealed a low proportion of fractalkine-expressing CD4+ and CD8+ T cells in both RA patients and controls. In addition, fractalkine was predominantly expressed in CD4+ T cells with a Th1-type cytokine expression profile. In RA synovium, fractalkine was detected in synovial macrophages, dendritic cells, endothelial cells, and a small proportion of T cells. The fractalkine receptor CX3CR1 was found in synovial macrophages, dendritic cells, and T cells as well as in synovial fibroblasts. Fractalkine stimulation of cultured synovial fibroblasts resulted in a marked upregulation of matrix metalloproteinase-2 (MMP-2) production. CONCLUSION: The results suggest that fractalkine may represent a Th1-type chemokine. Upregulation of MMP-2 production in synovial fibroblasts upon fractalkine stimulation in vitro supports the hypothesis of a proinflammatory role of this chemokine in RA.

Adult↗
PubMed2002

Side-effects after inhalational anaesthesia for paediatric cerebral magnetic resonance imaging.

BACKGROUND: The aim of this study was to evaluate the type, incidence and duration of postprocedure side-effects in 168 children within the first 72 h after inhalational anaesthesia for magnetic resonance imaging (MRI). METHODS: Premedication and induction followed standardized routines. Maintenance of anaesthesia was performed with inhalational anaesthetics solely: isoflurane (n=60 of 112; 53%), sevoflurane (n=32 of 112; 29%), desflurane (n=12 of 112; 11%) or halothane (n= 8 of 112; 7%) using a strapped on face mask (FiO2=0.4; flow 5 l.min-1). When indicated, gadolinium was administered (n=45; OF 112; 40%). RESULTS: One hundred and twelve of 168 parents (67%) responded to questionnaires. In these 112 children, pathological MR findings were found supratentorially (n=31; 28%), infratentorially (n=9; 8%), extracerebrally (n=12; 11%) or combined (n=9; 8%). In 56 of these 112 children (50%), 14 different side-effects were reported. One hour after anaesthesia, 55 children suffered between one and four side-effects. Neurological side-effects were associated with age > or = 5 years (P < 0.01) or infratentorial pathophysiology (P < 0.01) and abdominal side-effects (P < 0.02), especially nausea (P < 0.001) with age > or = 5 years. CONCLUSIONS: Our findings indicate the need to inform parents of the incidence and variability of side-effects after inhalational anaesthesia for minimally invasive, diagnostic procedures, such as MRI.

Adolescent↗