PubMed Health⌕ Search

Biomedical subjects

R Engst

Publications and source records attributed to R Engst.

At least 37 records · Page 2Linked to original sources
PubMed1984

[The enzymatic degradation of DDT. 1. Main degradation pathways].

First investigations on the degradation of DDT were already carried out at the beginning of its application. Its metabolism, however, is not yet absolutely clear till now. Main degradation pathways are considered: Reductive dechlorinations, successive dehydrochlorinations to unsaturated compounds as well as oxidations to aldehydes, alcohol and carboxylic acid. Decarboxylations of carboxylic acids are considered to be dependent on the species concerned. Between various organisms only quantitative differences are evident.

Aedes↗
PubMed1983

[Formation and occurrence of cancer-producing hydrocarbons in cereals and possibilities for their reduction].

According to the authors' investigations every inhabitant of the GDR takes between 0.2 and 1.0 mg BaP. per year by food consumption including amounts of 0.03 to 0.17 mg on account of cereals and mill products. For the contamination of cereals the following sources are in consideration: environmental contamination on account of industry dust (distant from industry 0.1 to 0.6, near to industry 0.3 to 4.2 micrograms BaP/kg), passing over from soil to plant (with model experiments with soils more than 10 000 micrograms BaP/kg up to 22.3 micrograms BaP/kg dry matter) as well as technologically caused contamination for instance by direct fume-and-gas drying (with the use of raw lignite up to 10 micrograms BaP/kg). As it can be concluded from model experiments BaP passes to flour at milling in dependence of the extraction rate. By separating the husks prior to milling more than 50% of BaP can be removed from the stock.

Air Pollutants↗
PubMed1982

Metabolism of alpha-hexachlorocyclohexane. Free metabolites in urine and organs of rats.

k1. The alpha-isomer of 1,2,3,4,5,6-hexachlorocyclohexane (HCH) is converted in rats to 1,2,4-trichlorobenzene, 2,3,4-trichlorophenol, 2,4,6-trichlorophenol, other trichlorophenols, and 2,3,4,6-tetrachlorophenol, which were excreted in urine. 2. Alpha-HCH is also converted to 3,4,6/5-pentachlorocyclohexene which is detectable in kidneys, but not in urine. 3. The results of this study are discussed with references to earlier work and to gamma-HCH metabolism.

Animals↗
PubMed1979

[Determination and the hygienic-toxicologic significance of patulin in fruit and fruit products].

The combination of extracting, chromatographic and fluorescence densitometric steps permits to determine patulin in fruits and fruit products with great precision and sensitivity. The limit of detection is 10 microgram/kg; the recovery rates range from 86 to 92% with a variation coefficient lying between 5.6 and 13.6%. Interferences due to patulin-simulating substances are widely excluded. Patulin concentrations ranging from 0.3 to 42 mg/kg were found in the brown-rotten portions of apples. Juices domestically prepared from healthy fruits and fruits rid of rotten portions, respectively, contained no patulin. On the contrary, patulin concentrations ranging from 0.02 to 0.3 mg/l were observed in commercial apple juices. As to products with subsequent mould infection, patulin values up to 50 mg/l were found in apple juices, and up to 0.4 mg/kg in peach preserves. In a further 24 commercial fruit and vegetable juices, patulin was not detectable even not in cider, in cereals which had gone mouldy spontaneously, and in bread samples. The fruits and fruit products were analysed not only for patulin, but also for aflatoxin and ochratoxin; the latter two, however, were found in none of the samples examined. The possibilities of manufacturing patulin-free products are discussed.

Chromatography, Thin Layer↗
PubMed1979

[Interactions of toxic trace elements with special regard to selenium].

The significance of the trace elements in nutrition is often decisively affected by the interaction of trace elements with other trace elements and of trace elements with other substances. These processes, which include synergistic and antagonistic effects, are of great importance not only to the essentiality, but also to the toxicity of trace elements. There is considerable experience with interactions of essential elements. There is considerable experience with interactions of essential elements or of elements in essential concentrations. On contrast, there is a scarcity of information pertaining to toxic effects that are influenced by synergisms and antagonisms. This situation is illustrated by some examples and especially by the role of selenium. It is shown that these problems deserve closer attention.

Cations↗
PubMed1979

[Effect of the trace element supply on element dependent enzymes in man].

Whole blood samples from 40 male and 40 female individuals were analyzed for zinc, copper, selenium and iron, and in part also for cadmium and lead. Correlations were established between the element contents and the activities of blood enzymes (carbo-anhydrase, leucine aminopeptidase, lactate dehydrogenase, alkaline phosphatase, glutathione peroxidase). The zinc-copper ratio exerted no effect on the zinc-dependent enzymes. There was a correlation between the glutathione peroxidase activity and the selenium content in whole blood (r greater than 0.73). A cluster analysis was performed. In women, the authors stated a significant effect of oral contraceptives especially on the zinc and copper balance. It was evidenced that detectable (more marked) changes in the mineral equilibrium are not produced in all cases by the contraceptives. Nevertheless, changes in the mineral equilibrium are likely to occur in 25% of all women. In the present study further changes (for example in enzymes) were observed in 50% of all women. The results obtained from the male individuals were indicative of certain relationships between the zinc-copper ratio and the content of total lipids or lipid fractions in human blood.

Adult↗
PubMed1979

[Determination of residues of the fungicide benzimidazole carbamic acid methyl ester and its metabolites 2-aminobenzimidazole and benzimidazole].

The authors describe a method for extracting and determining benzimidazole carbamic acid methyl ester (MBC) in the presence of its metabolites 2-aminobenzimidazole and benzimidazole. The determination is performed thin-layer and paper chromatographically using visual spot comparison. A sensitive biological method is employed for the detection of MBC. The metabolites are assayed by chemical procedures. The smallest amounts of residues that the authors could detect were: 0.01 p.p.m. of MBC and approximately 0.2 p.p.m. of the metabolites, the recovery rate ranging from 70--85%.

Benzimidazoles↗
PubMed1979

[Contamination of foods and feeding stuffs from selected areas of the Erfurt district with lead and cadmium. I. Determination of lead and cadmium in vegetable material by inverse voltammetry].

An inverse voltammetric method is used for determining the trace elements lead and cadmium in vegetable foods and feeding stuffs. The organic meterials are mineralized by nitric acid vapour and, in the second stage, with the addition of perchloric acid. The procedure is very sensitive and suited for routine work. The detection limits are: 0.66 ng/ml for lead, and 0.30 ng/ml for cadmium. The error of the method is: VPb = 20.5% and VCd = 28.6%. The respective recoveries of amounts of lead and cadmium added to the samples prior to digestion were: 102.0 +/- 10.8% and 101.6 +/- 11.4%.

Animal Feed↗
PubMed1977

[Comparative studies on the contamination of foods by cancerogenic hydrocarbons in the Soviet Union and in the GDR (author's transl)].

Investigations on the relationship of the environmental contamination with cancer are shown to be necessary. Epidemiologic investigations point to a connection of the increased occurence of cancer in the gastro-intestinal tract with dietetic factors. The high cancer rate in the gastro-intestinal tract (amongst other factors) is discussed as a result of the uptake of exogenic foreign matterns with the food. The possibilities of the contamination by cancerogenic compounds are summarized. The necessity of international co-operation in the field of finding out, as far as possible, sources and degree of food contamination by cancerogenic compounds is motivated beginning with polycyclic aromatic compounds, whereby at present benzo-(a)-pyrene comes into question as a reference substance. The laying down of controllable hygienic norms as preliminarily tolerable limits in the proper sense of an unavoidable dose are discussed. They could be a basis of oncological preventive measures (minimization or elimination of cancerogenic compounds in foods).

Benzopyrenes↗
PubMed1977

[Contamination of the environment with hexachlorobenzene].

The causes of hexachlorobenzene (HCB) contamination of the environment are of complex nature. Besides the microbial metabolism of lindane to HCB, the pyrolysis of pentachlorophenol (wood impregnation), the chlorine treatment of lignin-containing lyes and possible contaminations with active agents which are industrially synthetized from polychlorbenzenes must be regarded as causes being in part still hypothetical.

Chemical Phenomena↗
PubMed1977

[Determination and occurence of aflatoxin M1 and B1 in milk and dairy products].

The described method enables a simultaneous identification and determination of aflatoxin M1 and B1 in milk and dairy products by means of a self-registering fluorescence spectrophotometer with a thin-layer chromatographic accessory, directly from the plate. The semiquantitative estimation on the thin-layer chromatographic plate enables also routine analyses in the hygienic practice. The recovery rates for aflatoxin M1 and B1 in milk are about 83 and 82%, respectively -- the detection limit is about 0.1 microng per kg. The recovery rates for aflatoxin M1 and B1 in milk powder are about 89 and 94%, respectively -- the detection limit is bout 0.5 microng per kg. The reproducibility is given with a standard deviation between +/- 1.1 and 6,3% and a variation coeffecient of 1.3 and 6.7, respectively. 4 of 24 analized samples of commercial winter milk were aflatoxin M1-positive, whereas aflatoxin B1 could not be found. One of the milk powder products, a sample of the infant food, "Ki-Na", made in the GDR, contained, however aflatoxin B1. Aflatoxin M1 could not be found. Food-hygienic-toxicological conclusions are discussed.

Aflatoxins↗