Biomedical subjects

D Ganser

Publications and source records attributed to D Ganser.

3 recordsLinked to original sources

PubMed2001

Microfabricated polycarbonate CE devices for DNA analysis.

The microchip capillary electrophoresis (CE) devices were fabricated in polycarbonate (PC) plastic material by compression molding. The molded devices were enclosed utilizing thermal bonding to another PC wafer. These thermal bonds do not yield up to an applied force equivalent to 150 psi. Aqueous fluid transport inside the plastic CE devices was enhanced by UV irradiation treatment of the hydrophobic polycarbonate plastic surfaces prior to thermal bonding. In comparison to glass microchannels, electroosmotic flow (EOF) in native PC channels is low and is independent of buffer pH at pH 7 and 9. UV irradiation of PC surfaces increases surface hydrophilicity and increases EOF. CE DNA separation was demonstrated in these PC CE devices with good resolution and run-to-run reproducibility. The on-chip PCR/CE analysis of a 500-bp region of bacteriophage lambda DNA was also demonstrated.

DNA↗

PubMed1998

Duplication of the Rdl GABA receptor subunit gene in an insecticide-resistant aphid, Myzus persicae.

Resistance to cyclodiene insecticides is associated with replacements of a single amino acid (alanine 302) in a gamma-aminobutyric acid (GABA) receptor subunit encoded by the single-copy gene Resistance to dieldrin (Rdl). Alanine 302 is predicted to reside within the second membrane-spanning region of the Rdl receptor, a region that is thought to line the integral chloride ion channel pore. In all cyclodiene-resistant insects studied to date, this same alanine residue is replaced either by a serine, or, in some resistant strains of Drosophila simulans, a glycine residue. Therefore, individuals can carry only two different Rdl alleles. In contrast, here we report the presence of up to four different Rdl-like alleles in individual clones of the green peach aphid, Myzus persicae. In addition to the wild-type copy of Rdl gene (encoding A302 or allele A), M. persicae carries three other alleles with the following amino acid replacements: A302-->Glycine (allele G), A302-->SerineTCG (allele S) and A302-->SerineAGT (allele S'). Evidence from direct nucleotide sequencing and Single Stranded Conformational Polymorphism (SSCP) analysis shows that at least three of these different Rdl alleles (i.e. A, G and S) are commonly present in individual aphids or aphid clones. Southern analysis using allele-specific probes and analysis of sequences downstream of the exon containing the resistance-associated mutation confirm the presence of two independent Rdl-like loci in M. persicae. One locus carries the susceptible alanine (A) and/or resistant glycine (G) allele while the other carries the two serine alleles (S or S'). Whereas resistance levels are correlated with the glycine replacement, the S allele was present in all aphid clones, regardless of their resistance status. These results suggest that target site insensitivity is associated with replacements at the first (A/G) but not the second (S/S') locus. Phylogenetic analysis of nucleotide sequences indicates that both putative aphid Rdl loci are monophyletic with respect to other insect Rdl genes and may have arisen through a recent gene duplication event. The implications of this duplication with respect to insecticide resistance and insect GABA receptor subunit diversity are discussed.

Alanine↗

PubMed1994

[A retrospective analysis of the treatment results in Hodgkin's disease in a radiotherapy clinic].

PURPOSE: Treatment results were reviewed in a retrospective analysis and compared with literature data. Prognostic factors for freedom from relapse and overall survival were identified. PATIENTS AND METHODS: We analyzed the history of 183 patients treated for Hodgkin's disease between 1977 and 1989 at the Department of Radiation Therapy at the University of Würzburg. There were 100 males and 83 females between 16 and 86 years of age. 70.5% of patients presented with early stage Hodgkin's disease (23.5% stage I and 47.0% stage II) and 29.5% had advanced stages (25.1% stage III and 4.4% stage IV). All patients were treated initially with radiotherapy, 114 had radiotherapy alone and 69 patients received combined modality treatment. RESULTS: Hundred and sixty-one patients (88.0%) reached a complete remission. Freedom from relapse was 73.7% at 5 years and 70.3% at 10 years for these patients, overall survival was 74.3% and 62.8% at 5 and 10 years for all patients. Prognostic factors for freedom from relapse were stage IV, B symptoms, age greater than 35 years and more than 3 involved lymph node regions. These factors also were relevant for overall survival, in addition mixed cellularity or lymphocyte depleted subtype, high erythrocyte sedimentation rate, failure to achieve a complete remission following initial treatment and relapse of Hodgkin's disease were identified as negative prognostic factors. Laparotomy staged patients who received radiotherapy only for stage I and II Hodgkin's disease had better outcome than clinically staged patients. Our data suggest that adequate therapy is able to reduce the impact of unfavourable prognostic factors. The outcome for patients with bulky mediastinal disease was similar to that in patients without a mediastinal mass. CONCLUSIONS: The optimal choice of treatment for patients with early stage Hodgkin's disease--combined modality treatment/radiotherapy alone/chemotherapy alone?--and for patients with advanced stages--consolidation radiotherapy?--remains an unresolved issue and needs further testing in large randomized trials considering acute and late complications. Staging laparotomy may be used only for a small group of patients who would receive radiotherapy alone as definitive treatment. Modifications of therapy clearly reduce the impact of negative prognostic factors.

Adult↗