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Biomedical subjects

G Engelhardt

Publications and source records attributed to G Engelhardt.

At least 73 records · Page 4Linked to original sources

Inhibition of phenylamide hydrolysis by Bacillus sphaericus with methylcarbamate and organophosphorus insecticides.

The degradation of the phenylamide herbicides monolinuron, linuron, and solan by cultures of Bacillus sphaericus ATCC 12123 was inhibited by the methylcarbamate insecticides metmercapturon, aldicarb, propoxur, and carbaryl and by the organophosphorus insecticides fenthion and parathion. The extent of inhibition was largest with metmercapturon and smallest with parathion inhibition of hydrolysis of the two phenylurea herbicides was greater than of the acylanilide compound. Tests with crude enzyme preparations of aryl acylamidase derived from B. sphaericus showed that the inhibition of the hydrolysis of linuron with methylcarbamates is a competitive one. The insecticides tested did induce the enzyme, nor could they serve as its substrate.

Amidohydrolases↗

[On the pharmacology of 9,10-dihydro-10-(1-methyl-4-piperidylidene)-9-anthrol (WA 335), a histamine and serotonin antagonist (author's transl)].

The substance 9,10-dihydro-10-(1-methyl-4-piperidylidene)-9-anthrol (WA 335) was examined for its antagonistic effects against histamine and serotonin, for its atropine-like properties as well as for a series of other qualities in comparison with cyproheptadine and pimethixene. The anti-histamine and anti-serotonin activities of compound WA 335 on the smooth muscle and the capillary do not only exceed that of cyproheptadine but also that of pimethixene. WA 335 shows an extremely strong binding to histamine and serotonin receptors. In the dose range in which it causes already an antamine effect, its oral absorption is very good. The anti-anaphylactic effect is much stronger than that of cyproheptadine. Like pimethixene and cyproheptadine, WA 335 has no distinct antagonistic qualities against bradykinin. The anticholinergic effects of WA 335 are dependent on the test object. In examinations on the bronchus of the guinea pig and the pupil of the mouse, the atropine-like efficiency corresponds to that of cyproheptadine; it is stronger on the stimulated vagus of the cat and less efficient than cyproheptadine on the stomach of the rat. WA 335 has distinct central atropine-like properties. It possesses a strong surface anesthetic activity. The effects of WA 335 on circulation are dependent on species. In contrast to pimethixene, compound WA 335 like cyproheptadine potentiates the effects of norepinephrine in cats. The reduction of the carotid sinus reflex in the cat is more distinct after WA 335 than after pimethixene and corresponds to that produced by cyproheptadine. Higher doses of WA 335 than are necessary to demonstrate antaminic effects are needed to provoke central nervous effects. WA 335 shows no analgesic potency in mice. The influence on body temperature in the rat is similar to that of cyproheptadine. WA 335 is equally efficient as pimethixene with regard to the inhibition of spontaneous motility and prolongation of barbiturate sleep in mice, and shows the same anti-emetic activity as does chlorpromazine in dogs. In contrast to chlorpromazine the behaviour of dogs and cats is distinctly altered already by doses of WA 335 which cause a slight sedation.

Analgesics↗

Purification and properties of an aryl acylamidase of Bacillus sphaericus, catalyzing the hydrolysis of various phenylamide herbicides and fungicides.

From Bacillus sphaericus ATCC 12123 an aryl acylamidase (EC 3.5.1.13) was purified to homogeneity by ion exchange chromatography, gel filtration, and polyacrylamide gel electrophoresis. The enzyme is inducible by various phenylamides of the acylanilide, phenylcarbamate, and methoxysubstituted phenylurea type. It has a molecular weight of 75,000. Enzyme activity was inhibited by sulfhydryl reagents, several metal ions, and 3,4-dichloroaniline (a product of linuron degradation). A requirement for divalent metal ions in enzyme activity could not be demonstrated. In the presence of 6 M urea an irreversible inactivation of the enzyme occurred. The hydrolysis of L-alanine-4-nitroanilide was competitively inhibited by puromycin.

Amides↗

Di(isononyl) phthalate (DINP) and di(isodecyl) phthalate (DIDP) are not mutagenic.

Recently there have been reports of liver and kidney tumors in rodents following long-term exposure to di(isononyl) phthalate (DINP). Mechanistic studies suggested that the liver tumors were a consequence of peroxisomal proliferation, whereas the kidney tumors (found only in male rats) were associated with induction of alpha(2u)-globulin. Because both peroxisomal proliferation and alpha(2u)-globulin are considered to be non-genotoxic carcinogenic processes, it seemed appropriate to investigate the genotoxic potential of DINP. Additional studies were also conducted on di(isodecyl) phthalate (DIDP), a structurally related substance that also induces peroxisomal proliferation, although it has not been tested in a carcinogenicity bioassay. The DINP was tested in Salmonella, in vitro cytogenetics and mouse micronucleus assays, whereas DIDP was evaluated in a mouse micronucleus test. All of these tests produced negative results, i.e. neither phthalate was mutagenic in any of the test systems. These data are consistent with results of other published and unpublished genotoxicity tests and provide support for the hypothesis that the liver and kidney tumors induced by DINP were the result of non-genotoxic processes.

Animals↗