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Biomedical subjects

M Wirth

Publications and source records attributed to M Wirth.

154 records · Page 9Linked to original sources
PubMed1983

Human embryonal cell carcinoma in nude mice.

A lymph node metastasis specimen from a human testicular embryonal carcinoma with elements of a choriocarcinoma was successfully xenotransplanted into nude mice and maintained until the tenth animal passage. Electron microscopy of the tumors in nude mice revealed details consistent with their epithelial origin. The xenotransplants retained the ability to synthesize human choriogonadotropic hormone during all animal passages, as evidenced by radioimmunoassay and immunoperoxidase staining techniques. The beta-human choriogonadotrophic hormone serum level correlated significantly with the tumor volume (p less than 0.05). The average amount of beta-human choriogonadotropic hormone measured in the serum of 94 animals was 587.8 ng/ml, ranging from 5 to 4000 ng/ml. The chromosomal analysis of tumors in nude mice revealed a human chromosomal pattern with modal numbers between 55 and 60 chromosomes, and a consistent trisomy of chromosome 1.

Animals↗
PubMed1982

Effect of linoleic acid-rich diet on blood pressure, lipids, catecholamines, and dopamine -beta-hydroxylase in spontaneously hypertensive rats.

Spontaneously hypertensive rats (SHR) and normotensive Wistar rats were fed a linoleic acid-rich (LAR) and -deficient (LAD) diet for 22 weeks, respectively. Although linoleic acid (LA) and arachidonic acid (AA) in serum and liver triglycerides markedly increased after a LAR diet, LA was significantly lower and AA was higher in SHR when compared to normotensive control rats. Thus, the percentage of both fatty acids remained different like in animals fed a commercial diet. On the contrary, in SHR and normotensive rats fed a LAD diet no differences in the LA and AA content could be found between the groups. In these rats, however, n-3 fatty acids (eicosapentaenoic and docosahexaenoic acids) in serum triglycerides were increased. Blood pressure, serum triglycerides and total cholesterol appeared unchanged, whereas HDL-cholesterol was increased after a LAR diet. Dopamine, adrenaline and noradrenaline content as well as dopamine-beta-hydroxylase activity were augmented in adrenal glands of SHR fed a LAR diet. In spite of distinct biochemical alterations the genetically determined hypertension in rats could not be influenced by a long-lasting diet containing a high amount of LA which has been proved to be effective on lowering blood pressure in other hypertensive rat models.

Animals↗
PubMed1981

Structural heterogeneity and subcellular distribution of nicotinic synapse-associated proteins.

Peripheral membrane proteins (Mr = 43,000) are associated with Torpedo membranes highly enriched in nicotinic receptor. These 43,000-dalton proteins are not required for ion translocation or other known receptor functions, but they have been implicated in constraint of the nicotinic receptor within the plane of the membrane bilayer. Sodium dodecyl sulfate-polyacrylamide electrophoresis allows partial resolution of the 43,000-dalton band into a doublet. We have carried out further analysis using two-dimensional gel electrophoresis, which reveals the existence of at least seven Coomassie blue-staining spots in the isoelectric focusing dimension. Peptide maps of the individual spots serve to elucidate the observed electrophoretic complexity. Three different membrane-bound proteins, designated v1, v2, and v3, were identified on the basis of their characteristic peptide maps which show no apparent homology in amino acid sequence. Two of these proteins, v1 and v2, are resolved into multiple spots in the isoelectric focusing dimension, but each group of isoelectric focusing variants has nearly identical peptide fingerprints. Of relevance to the putative role of these proteins in synaptic or receptor supramolecular structures is the observation that only v1 is exclusively membrane bound, and co-purifies with receptor whereas both v2 and v3 are also prominent proteins of the cytoplasm and are depleted from membrane fractions most enriched in receptor. These proteins may interact in the formation or maintenance of synaptic and nicotinic receptor supramolecular structures.

Animals↗
PubMed1981

Characterization of effector cells responsible for cell-mediated cytotoxicity in patients with carcinoma of the prostate.

In earlier experiments it has been shown that cellular cytotoxicity of patients with prostatic carcinoma (CaP) as measured by cytolysis of EB 33 target cells correlates with the extent of their tumor lesion: a high grade of cytotoxicity was observed only when CaP was confined to gland. In order to define a possible in vivo immunological host-tumor interaction, further characterization of the type of effector cell responsible for in vitro killing has been attempted. Effector cells could be either tumor-specific sensitized T cells, K cells, macrophages or NK cells. Antibody-dependent K-cell activity could most likely be excluded, since autologous and homologous serum did not affect the extent of EB 33 killing when added to the test medium. Further separation of effector cells by nylon wool columns resulted in increased cytolysis of EB 33 target cells. This can be due either to tumor-specific T-cell-mediated mechanisms or to an increased natural killer cell activity, as macrophages and B cells were significantly removed by this measure. Separation of T and NK cells is necessary to ascertain the effector cell responsible for the in vitro killing of tumor cells derived from human CaP.

Adult↗
PubMed1976

Detection of HBsAg and HBsAb in sweat.

HBsAg was detected in the sweat of 9/18 seropositive, but 0/20 seronegative probands. Frequency of detection correlated to serum titer of HBsAg, blood contamination and efficiency of sweat concentrating. On base of quantitative evaluations it is assumed, that blood and/or plasma contaminations are responsible for the presence of HBsAg in sweat. Since HBsAg and hepatitis virus B are of similar diameter, this mechanisms should work on the infectious agent too. Thus HBsAg could prove a marker, to calculate the infectivity of sweat in comparison to the corresponding serum specimen (10(-6) to 10(-7). HBsAb was detected in sweat too and was confined to HBsAb-seropositive probands (4/5). It is discussed, that the presence of HBsAb in sweat could provide protection against reinfections by contact and thus contribute to homologous immunity in hepatitis B.

Antibodies↗
PubMedDate not supplied

Direct monitoring of molecular recognition processes using fluorescence enhancement at colloid-coated microplates.

Direct monitoring of recognition processes at the molecular level is a valuable tool for studying reaction kinetics to assess affinity constants (e.g. drugs to receptors) and for designing rapid single step immunoassays. Methods currently used to gain information about binding processes predominantly depend on surface plasmon resonance. These systems use excitation with coherent light in attenuated total reflection geometry to obtain discrimination between surface-bound and free molecules in solution. Therefore labeling of the compounds is not necessary, but due to the complexity of the measuring setup the method is rather costly. In this contribution we present a simple method for performing kinetic single step biorecognition assays with fluorophore labeled compounds using the fluorescence enhancement properties of surface bound silver colloids. Silver colloids are bound to standard microplates via silanization of the plastic surface. Fluorophores close to this colloid coated surface show a significant gain in fluorescence compared to fluorophores farther away in the bulk solution. Therefore discrimination between surface bound and free fluorophores is possible and the binding of, for example, fluorophore labeled antibodies to antigens immobilized on the colloid surface results in increasing fluorescence intensity. Utilization of standard microplates makes this method fully compatible with conventional microplate processing and reading devices. Neither excitation with coherent laser light nor ATR geometry is required, the measurement is performed in a standard fluorescence microplate reader in front face geometry with a xenon flash lamp as excitation source. Methods for the preparation of colloid-coated microplates and fluorescence-enhanced biorecognition assays are presented. Additionally the dependence of the system performance on the structure and properties of the metal colloid coated surface is described. A two-component biorecognition model system shows a detection limit in the subnanomolar range. The ease of colloid-surface preparation and the high sensitivity makes fluorescence enhancement at colloid-coated microplates a valuable tool for studying reaction kinetics and performing rapid single-step immunoassays.

Adsorption↗
PubMedDate not supplied

Ketoprofen-poly(D,L-lactic-co-glycolic acid) microspheres: influence of manufacturing parameters and type of polymer on the release characteristics.

The effect of manufacturing parameters on the size and drug-loading of ketoprofen-containing biodegradable and biocompatible poly(DL-lactic-co-glycolic acid) (PLGA) microspheres prepared by the solvent evaporation method was investigated. For both drug-free and drug-loaded microspheres, smaller microspheres with a narrower size distribution were obtained when the stirring rate or the volume of the organic phase was increased. Incorporation of ketoprofen was found to increase with increasing volume of the organic phase and decreasing pH of the aqueous phase, but was independent of the acidity and the inherent viscosity of the PLGA used. The biphasic release profile of ketoprofen from the microspheres was dependent on the type of PLGA as well as the size and drug-loading, two parameters governed by the manufacturing process. The first burst effect was found to increase with the drug content, reduction of size of the microspheres and increasing inherent viscosity of the matrix, whereas acidity of the PLGA had no effect on the release of this acidic drug. A vigorous first burst effect was associated with reduced sustained delivery of ketoprofen, the rate of the delayed release phase being dependent on the inherent viscosity of the matrix, the size, the payload and the pH during preparation of the microspheres. Thus, by selection of the manufacturing parameters and the type of PLGA, it is possible to design a controlled drug delivery system for the prolonged release of ketoprofen, improving therapy by possible reduction of time intervals between peroral administration and reduction of local gastrointestinal side effects.

Anti-Inflammatory Agents, Non-Steroidal↗