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Biomedical subjects

B Hoffmann

Publications and source records attributed to B Hoffmann.

283 records · Page 16Linked to original sources
PubMedDate not supplied

Investigations on the occurrence of non-extractable residues of trienbolone acetate in cattle tissues in respect to their bioavailability and immunological reactivity.

3H-trienbolone acetate (TBA) was injected/implanted in cattle and the distribution of radioactivity in liver and muscular tissue was determined, applying rigorously standardized organic or aqueous extraction procedures, either directly or following enzymatic hydrolysis and proteolytic procedures. These steps yielded almost 100% recovery of the radioactivity and indicated that only between 5% and 15% of the total residues present was extractable with organic solvents. The remaining radioactivity was either soluble in aqueous media or stayed bound to tissue structures. Similarly processed liver tissue from a calf treated with 3500 mg TBA 68 days prior to slaughter was examined by applying radioimmunoassay for the determination of TBA/trienbolone (TBOH). Indications of the presence of trienic-steroid type residues were only obtained for fractions containing residues extractable with organic solvents.

Anabolic Agents↗
PubMedDate not supplied

Technical aspects of plasma leakage prevention in microporous capillary membrane oxygenators.

A limiting factor in using microporous capillary membrane oxygenators (CMO) for long-term extracorporeal lung support is leakage. Application of heparin-coated CMO requires additional examination because leakage is probably caused by the temperature conditions of the gas, the blood and the circuit environment, and the surface tension phenomenon at the micropores. The authors designed a thermostatized box in which the temperature of flowing gas (Tg) and blood (Tb), and the interior temperature of the box (Ti) could be regulated independently. Tb was adjusted to the animal's body temperature, and Tg was kept about 2 degrees C higher to prevent condensation of the evaporated fluid from the blood side, through the micropores, into the gas phase. Ti was maintained between Tg and Tb. The saturated outlet gas could therefore condense only outside the box. This system was used during 5 days of venovenous bypass using a covalently heparin-bonded (Carmeda) CMO (Maxima, Medtronic) in four adult sheep. No plasma leakage occurred, the surface tension of condensate water remained constant, and the gas exchange capacity of CMO was unchanged.

Animals↗
PubMedDate not supplied

[The relationship of plasmids from environmental Yersinia isolates and the virulence plasmid of enteropathogenic Yersinia strains].

The human pathogenic strains of Yersinia harbour a conserved plasmid carrying the Yop virulon. The virulence plasmid of Yersinia enterocolitica strains belonging to the serogroups O:3 and O:9 were used as probes to detect homologous sequences in plasmids of "avirulent" Yersinia strains. "Avirulent" Yersinia strains (Y. enterocolitica biogroup 1A, Y. intermedia, Y. kristensenii and Y. frederiksenii) lack the virulence plasmid. They are widely distributed in the environment and can frequently be isolated from clinical samples. Hybridisation experiments revealed a number of common genetic elements of the virulence plasmid and the plasmids of "avirulent" Yersinia strains. These elements were identified as genes involved in plasmid replication, as an endonuclease gene and as mobile genetic elements. However, none of the plasmid encoded virulence genes was present in the plasmids of "avirulent" Yersinia strains. The frequent occurrence and the possible etiological relevance of "avirulent" isolates will be discussed.

Animals↗
PubMedDate not supplied

[Interaction of sex steroids, prostaglandins (6-keto-PGF1 alpha, PGF2 alpha) and beta adrenergic agonists (adrenaline, fenoterol-Partusisten) in the human non-pregnant myometrium in vitro].

The in vitro effects of epinephrine and fenoterol (Partusisten) on contractility and prostaglandin (6-keto-PGF1 alpha, PGF2 alpha) production of human, non-pregnant myometrial strips dependent on the phase of the menstrual cycle and after pretreatment with estrogens and progesterone are reported. Superfusion of epinephrine (100 ng/ml) stimulated contractility and PG-synthesis of myometrial tissue from the proliferative phase of the cycle, whereas fenoterol (10 ng/ml) had only a little inhibitory effect. After pretreatment with conjugated estrogens (Presomen) the maximal epinephrine-stimulated contractions were correlated to a further increase in PGF2 alpha-synthesis even during fenoterol superfusion. In myometrial tissue obtained during the secretory phase of the cycle, both epinephrine and fenoterol had a significant inhibitory effect on spontaneous contractions associated with an increase in 6-keto-PGF1 alpha-production. After pretreatment with an estrogen-progestin combination (Primosiston) fenoterol superfusion resulted in a complete inhibition of myometrial contractions. These results demonstrate that estrogens increase the myometrial sensitivity to catecholamines leading to increased contractility and increased PGF2 alpha-synthesis, whereas progesterone probably mediates the beta-adrenergic inhibitory effect on myometrial contractions. Thus, the contractions inhibiting effect of the betamimetic drug fenoterol associated with decreased PGF2 alpha- und increased prostacyclin (PGI2) synthesis depends on the effect of progesterone in human, non-pregnant myometrium.

6-Ketoprostaglandin F1 alpha↗