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Biomedical subjects

L Bauer

Publications and source records attributed to L Bauer.

At least 73 records · Page 4Linked to original sources
PubMed1985

Synthesis, metabolism, and disposition of the antiinflammatory 3-[2-(4-methylphenyl)-thioethyl]-sydnone-5-14C in the rat.

The synthesis, as well as the in vivo and in vitro disposition, of 3-[2-(4-methylphenyl)thioethyl]-sydnone-5-14C (5) in the rat is described. After intraperitoneal injection of a single dose of 5 in female Sprague-Dawley rats, the distribution and excretion of radioactive substances was monitored (24 h). Radioactivity in the blood declined in a biphasic manner with half-lives of 0.55 and 15.2 h for the alpha- and beta-phase, respectively. About 8% of the administered radioactivity was detected in feces and approximately 90% in urine (24 h). In 3.75 h, 50% of the radio-dose was excreted in the urine. Tissue distribution studies demonstrated a selective uptake of radioactivity only by the adrenal glands and the ovaries. The radioactivity in these organs reached a maximum approximately 1 h after dosing and then declined rapidly. None of the parent drug was excreted from such a single dose (i.p. injection) which indicated rapid in vivo metabolism. Nor could there be found any metabolites related to the whole structure, for example, the sulfoxide or aromatic hydroxy compounds. The sydnone 5, its sulfoxide and unconjugated metabolites were detected and quantitated by GC/MS methodology using unlabelled authentic samples. Radioactive carbon dioxide was not detected during the in vivo or in vitro experiments, nor was it released from alkaline urine samples upon acidification. Radiolabelled urinary metabolites were glycolic acid-1-14C 9 (34%), its glycine conjugate 10 (52%) and 3-vinylsydnone-5-14C 11 (4%).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

[Phototoxic effect of polycyclic aromatic compounds on human fibroblast cultures].

The phototoxic effects of polycyclic aromatic hydrocarbons (PAH) benzo(a)pyrene, benzo(a)anthrazene, indeno(1,2,3-cd)pyrene, fluoranthene and perylene, and their relation to the known carcinogenicity of these compounds was examined with human fibroblastic cultures. Using different light filters it could be demonstrated that phototoxic effects on the cell cultures only occur with wave lengths shorter than 400 nm, that is in the longwave UV-region. With wave lengths longer than 400 nm, that is in the visible region of light, no cytotoxic effects could be detected. Irradiated with long-wave UV, the highly cancerogenic compounds benzo(a)pyrene, and indeno(1,2,3-cd)pyrene proved to be highly cytotoxic, the moderately cancerogenic benzo(a)anthrazene turned out to be distintly cytotoxic, fluoranthene supposed to be not cancerogenic, proved to be only slightly cytotoxic. Perylene that is considered not cancerogenic either, reacted completely indifferent. These results are completely compatible with those obtained earlier with ciliata (unicellular protozoa). They confirm the assumption that the so-called ciliata test (Tetrahymena pyriformis) can be used as a practicable test system to ascertain the carcinogenicity of PAH.

Carcinogens↗
PubMed1983

Bacterial and fungal isolates from Equidae with ulcerative keratitis.

Gram-negative bacteria were the most common microbial isolates from 38 eyes of 37 horses with ulcerative keratitis. Pseudomonas sp, Enterobacter group, and Acinetobacter sp were the most prevalent. Fungi were cultured from 15 eyes and included 7 genera, with Aspergillus sp being the most prevalent. Ten of the eyes with fungal keratitis had been treated with corticosteroids. Eleven of 38 eyes had mixed bacterial and fungal infections. Clinically, the most severe cases were those in which Aspergillus and gram-negative bacteria existed in a mixed infection. On the basis of susceptibility testing, gentamicin was highly efficacious (88.4%) against all bacterial isolates. Cephaloridine was slightly more efficacious than gentamicin against the gram-positive organisms. Only 32.3% of the gram-negative isolates were susceptible to chloramphenicol. Of the relatively small number of gram-positive organisms isolated, streptococci were more often susceptible to chloramphenicol, whereas staphylococci were more often susceptible to gentamicin.

Animals↗
PubMed1982

[Detection of Gm, Km, and EsD phenotypes in the dental pulp of human cadavers ].

Dental pulps of human cadavers (some of them putrefied) were investigated to determine the immunoglobulin markers G1m(1,2,3), G3m(5,10,21), Km(1), and the isozyme EsD. Reliable results were obtained in the Gm and Km typings, also in putrefied or skeletonized cadavers. EsD typings revealed that the phenotypes EsD(1) and EsD(2-1) are expressed in the dental pulp and can also be detected there in putrefied cadavers.

Carboxylesterase↗
PubMed1981

Syntheses and biological evaluation of 2- and 9-aminobenzonorbornenes as conformationally rigid analogs of amphetamines.

Isomers of the 2- and 9-aminobenzonorbornenes were prepared as rigid analogs of amphetamine and were employed to study the conformational requirements of indirectly acting sympathomimetic agents. Of this series of isomeric amines, the exo-2 and anti-9 isomers closely resemble the fully extended conformation of amphetamine. The other two amines, the endo-2 and syn-9 isomers, conformationally resemble the folded conformation of amphetamine. The isomers that resemble the extended conformation of amphetamine increased the spontaneous motor activity in mice while the isomers resembling the folded form either decreased or had no effect on motor activity. These compounds also were studied for their ability to accelerate the efflux of tritiated norepinephrine from vesicular and nonvesicular storage sites of isolated perfused rabbit atria; either alpha-methyl-p-tyrosine- or reserpine-pretreated rabbits were used. Amphetamine and the exo-2 and anti-9 isomers of aminobenzonorbornene could accelerate norepinephrine efflux from either compartment while the endo-2 and syn-9 isomers could accelerate the efflux from only the nonvesicular compartment at the concentrations studied. Fenfluramine and methylphenidate also were studied for their ability to accelerate efflux. Fenfluramine and methylphenidate resembled the aminobenzonorbornenes that correspond to the folded conformation of amphetamine in their ability to accelerate the efflux from nonvesicular storage. However, fenfluramine also resembled amphetamine and the aminobenzonorbornenes corresponding to the extended conformation of amphetamine in its ability to accelerate efflux from vesicular storage sites. The response to methylphenidate was similar to that of the aminobenzonorbornenes resembling the folded conformation of amphetamine.

Amphetamines↗
PubMed1977

[On the increase of phototoxic activities of polycyclic aromatic hydrocarbons produced by dish detergents (author's transl)].

Several bands of dish detergents were found in high dilutions to increase phototoxic cell damage produced by polycyclic hydrocarbons such as benzo(a)pyrene. A comparable increase in phototoxicity in the presence of detergents was observed following the phagocytic ingestion of photodynamically active soot particles by the test organisms, Tetrahymena pyriformis (ciliate). The results are considered in the light of earlier reports on increased carcinogenicity following detergent action of one of the brands used in this investigation (P) on benzo(a)-pyrene. Possible mechanisms of action of detergents producing the increase in respective activities are discussed.

Animals↗
PubMed1976

[On the interaction of polycyclic aromatic hydrocarbons and light with regard to its syncarcinogenic effects (author's transl)].

The rapidly growing pollution of the human biosphaere with potentially carcinogenic agents gives increased relevance to questions concerning the interaction of both chemical and physical agents in carcinogenesis. One such combination of environmental agents - that between polycyclic aromatic hydrocarbons and light - which heretofore has received little attention from workers in the field of environmental research, was investigated in the present paper. The phototoxic (cytotoxic) effects of carcinogenic aromatic hydrocarbons was demonstrated using ciliates of the species Tetrahymena pyriformis as the sensitive substrate. The experiments were conducted both with the chemically pure compounds and with native soot containing the adsorbed hydrocarbons. The following results were obtained: 1. Phototoxicity for ciliates of the highly carcinogenic benzo(a)pyrene may still be demonstrated in dilutions containing but 2 ppb (mug/l) of the substance, while the non-carcinogenic benzo(e)pyrene and fluorenthene are only weakly toxic in much higher concentrations. 2. The combination of benzo(a)pyrene and fluoranthene produced neither an additive nor a quenching effect, i.e., the resulting phototoxicity merely reflected the action of benzo(a)pyrene. 3. No phototoxic effect was observed in case of the fluorescent carcinogen, aflatoxin B1, in concentrations up to 200 ppb. This is taken to indicate that the property of fluorescence of carcinogenic substances by itself does not account for the phototoxic phenomenon. 4. The intense phototoxic activity of native soot ingested by the ciliates was shown to be dependent on the amount of polycyclic hydrocarbons contained. 5. Removal of polycyclic aromatic hydrocarbons from the soot particles by extraction with benzene resulted in the loss of phototoxic activity.

Aflatoxins↗
PubMed1975

Isolation and identification of three new flavones from Achillea millefolium L.

Column chromatography on silica gel of a petroleum ether extract of the flowering heads of Achillea millefolium L. allowed three flavones to be separated and identified. Spectral studies (PMR, mass spectrometry, and UV) and a comparison with data for compounds reported in the literature established the flavones as 5-hydroxy-3,6,7,4'-tetramethoxyflavone, artemetin, and casticin. These compounds have not been reported previously as constituents of A. millefolium.

Flavonoids↗