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Biomedical subjects

W Butte

Publications and source records attributed to W Butte.

At least 19 recordsLinked to original sources
PubMed2006

Revised reference value for pentachlorophenol in morning urine.

Reference values are continuously derived by the Human Biomonitoring Commission of the German Federal Environment Agency to give help in assessing the exposure of individuals or population groups in comparison to the background exposure. As environmental conditions may change reference values should be checked periodically and they have to be updated, if new data become available. The results of the German Environmental Survey 1998 (GerES III) showed the decreasing pentachlorophenol (PCP) exposure of the German adult population. Therefore, the reference value for PCP in morning urine was lowered: from 8 to 5 microg/l for adults (aged 18-69 years) living in homes where wood preservatives had not been used.

Adolescent↗
PubMed1999

A spectrophotometric assay for pyrethroid-cleaving enzymes in human serum.

A direct continuous spectrophotometric assay to measure pyrethroid-cleaving enzymes in human serum was developed using cis- and trans-alpha-naphthyl-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane carboxylate (cis- and trans-naphthyl-Cl2CA). These substrates show a structure very similar to the pyrethroids most often used (e.g. permethrin, cyfluthrin). The method is based on an increase in absorbance at 321 nm which occurs with the hydrolysis of the alpha-naphthyl esters to alpha-naphthol. The assay was optimised regarding type of buffer, pH and substrate concentrations, it was linear for at least 10 min at 37 degrees C. These esterases were completely inhibited by bis-(4-nitrophenylphosphate), a specific carboxyesterase inhibitor. They displayed a great individual variability in human serum, activities were between less than 40 and 1000 U/l for cis-naphthyl-Cl2CA, between less than 40 and 2000 U/l for trans-naphthyl-Cl2CA, respectively. However, a correlation of enzyme activity to sex or age could not be observed. Furthermore, the activity of pyrethroid-cleaving esterases did not correspond to the activities of acylesterase, arylesterase, acetylcholinesterase or butyrylcholinesterase.

Esterases↗
PubMed1995

Validation of estuarine gammarid collectives (Amphipoda: Crustacea) as biomonitors for cadmium in semi-controlled toxicokinetic flow-through experiments.

Concentrations of chemicals in organisms are regarded as being indicators of the bioavailable fraction of those substances in the environment. Three gammarid collectives (assemblages) from the Weser-estuary (NW Germany), showing different species compositions, were used as experimental units to evaluate their suitability as biomonitors. Uptake and clearance of cadmium was investigated in semi-controlled dynamic flow-through tests. Kinetic data obtained from two compartment models confirmed a net accumulation strategy of gammarids for Cd and resulted in similar bioconcentration factors (BCFs) within the same experimental treatments. Deviations in bioconcentration factors between two treatments (BCFs: 377-542 vs 947-1190, based on dry wt) obtained under similar exposures (17 +/- 2 and 23 +/- 2 microg Cd litre(-1)) could not be assigned to significant fluctuations of both Cd levels and particulate matter in the flow-through systems. The biological half-life of Cd in gammarids was 6 to 12 days. It is concluded that gammarid collectives of different species composition may be used as experimental units in biomonitoring studies. This conclusion was confirmed by homogeneous Cd concentrations in field samples of gammarids from the Weser-estuary (0.34 +/- 0.03 mg kg(-1) dry wt., mean +/- 95% confidence intervals, N = 58).

Journal Article↗
PubMed1994

Kinetics of bioconcentration and clearance of 28 polychlorinated biphenyl congeners in zebrafish (Brachydanio rerio).

Bioconcentration experiments were performed on 28 polychlorinated biphenyl (PCB) congeners with NCl = 2 to NCl = 10, evaluating them simultaneously. Bioconcentration factors (BCFs) were calculated from the uptake rate constant (k1) and the clearance rate constant (k2) as BCF = k1/k2. BCFs on a wet weight basis ranged from 7710 to 940,000. They were correlated with octanol-water partition coefficients (P). The curvilinear relationship between log BCF and log P based upon data covering the log P range 5.06 to 8.18. About a log P of 7.38, a range of "optimal lipophilicity," results in highest BCFs for PCBs, above which the degree of bioconcentration decreases.

Animals↗
PubMed1994

[Concentration of biocides in indoor rooms using pyrethroids as an example].

Pyrethroids are an analogous substance group to one of the oldest known, naturally occurring insecticides pyrethrum and have replaced a number of pesticides such as Lindane, DDT and PCP on the market. Biocides are more persistent indoors than in nature, which could lead to permanent health hazards for the people concerned. Within a few days after application pyrethroids are rarely detected in room air but can be traced for a long time on textiles, furniture and in dust particles (3, 8). The investigation results of approx. 100 analyses from dust and carpet samples show that approx. 1/3 of these samples are positive for at least one pyrethroid and contain a concentration of > 2 mg substance per kg sample. The evaluation of 35 air samples taken from rooms where substances containing pyrethroids had been used at least a month prior to the investigation (the samples were sampled on active charcoal or Chromosorb) showed that pyrethroids could no longer be traced above the detection limit of 0.05-0.1 micrograms/m3. We therefore think that when investigating a contamination of rooms by biocides it is more advisable to determine pyrethroid and its synergists in the suspended dust portion and corresponding dust sample rather than analysing air by adsorption to active charcoal, Chromosorb or other carrier materials. From the observed concentrations of biocides one could conclude that in an indoor setting secondary contamination by biocides plays a more significant role in the total-body-load than that of air contamination.

Air Pollution, Indoor↗
PubMed1991

Kinetics of bioaccumulation and clearance of isomeric hexachlorocyclohexanes.

Bioaccumulation experiments were performed on the hexachlorocyclohexane isomers alpha-HCH, beta-HCH, gamma-HCH and delta-HCH, testing them simultaneously. Bioaccumulation factors (BCFs) were calculated from the uptake rate constant (k1) and the clearance rate constant (k2) as: BCF = k1/k2. The BCFs of alpha-HCH (1100 +/- 175) and gamma-HCH (920 +/- 131) were similar. The BCFs of beta-HCH (1520 +/- 276) and delta-HCH (1640 +/- 269), also similar, were significantly higher than those of the alpha- and gamma-isomers.

Animals↗
PubMed1991

The induction of DNA strand breaks and formation of semiquinone radicals by metabolites of 2,4,5-trichlorophenol.

The industrial pollutant 2,4,5-trichlorophenol (2,4,5-TCP) was metabolized with postmitochondrial liver fraction from Aroclor-1254 induced rats. The generated metabolites induced single strand breaks in PM2 DNA. Among the metabolites produced are the 3,4,6-trichlorocatechol (TCC) and the 2,5-dichlorohydro-quinone (DCH), whereby the induction of DNA scission by DCH was approximately one hundred times greater than that of TCC. In the 2,4,5-TCP metabolization mixture radicals were observed by ESR. They were identified as the semiquinones of TCC and DCH. ESR studies confirmed that both TCC and DCH autoxidize in aqueous solution to their semiquinone radicals. The involvement of reactive oxygen species in the DNA strand scission was demonstrated by using DMSO, SOD, and catalase as scavengers. Inhibition of strand breaks with the scavenger enzymes did not give homogeneous results for DCH and TCC. This indicated that the directly damaging species might be different for DCH and TCC.

Animals↗
PubMed1983

The determination of pentachlorophenol and tetrachlorophenols in wadden sediment and clams (Mya arenaria) using triethylsulfonium hydroxide for extraction and pyrolytic ethylation.

A method to determine the concentration of pentachlorophenol and tetrachlorophenols in wadden sediments and clams is described. This method involves the extraction of lyophilized specimens with toluene under acidic conditions and the back extraction of the chlorophenols into a methanol/water solution of triethylsulfonium hydroxide. Upon injection of the methanol/water phase into the gaschromatograph a pyrolytic ethylation is performed and the ethylethers of pentachlorophenol and tetrachlorophenols formed thereby are separated in quartz capillary columns and detected by an electron capture detector. Using tribromophenol as internal standard the recovery rates for the chlorophenols were within the range of 76.7 and 98.8%. The method described does not require any evaporation or chromatographic clean-up steps. The detection limit was found to be 2 nmol/kg (approximately 500 ng/kg) for sediment and 0.1 mumol/kg (approximately 25 micrograms/kg) for clams. Its accuracy was verified by gaschromatography-mass spectrometry experiments.

Animals↗
PubMed1981

[Comparative determination of transcortin, total cortisol and free cortisol in the plasma of mothers, newborn and non-pregnant women (author's transl)].

We determined plasma transcortin, total cortisol and free cortisol in mothers, new borns and nonpregnant women. The blood samples were drawn immediately upon delivery. The mothers had significantly higher levels of total cortisol as well as free cortisol and transcortin when compared to non-pregnant women. The new borns had higher levels of total cortisol and free cortisol but unchanged levels of transcortin in comparison to normal subjects. Significant differences were also found with respect to total protein and albumin in all groups.

Blood↗
PubMed1978

Detoxication methods for bromureide poisoning. Comparison of haemodialysis, haemofiltration and haemoperfusion on bastard dogs.

The efficiency of different detoxication methods for Carbromal intoxications was evaluated on bastard dogs using haemofiltration, haemodialysis and haemoperfusion with coated charcoal and polystyrene resins. Clearance rates and eliminated amounts of Carbromal and bromine were compared. Haemoperfusion is most effective in the elimination of Carbromal and haemodialysis for removal of bromide ions. Haemofiltration was least effective for both and should therefore not be used for the treatment of Carbromal intoxications.

Animals↗
PubMed1977

P-Aminobenzoic acid derivatives. Mode of action and structure-activity relationships in a cell-free system (Escherichia coli).

The agonistic and antagonistic effects of nuclearly substituted p-aminobenzoic acids (PABA) on the folate-synthesizing system of E. coli have been studied in whole cell and cell-free systems. All studied derivatives form dihydropteroic acid analogues in the presence of a cell-free folate-synthesizing enzyme system. A thin-layer chromatographic system has been elaborated to determine the rate of analogue formation in the cell-free system. Physicochemical parameters of the PABA derivatives, such as pKa, pi, and Rm values, have been determined. These values have been used in a structure-activity analysis which revealed that the rate of analogue formation in the absence of PABA is independent of the lipophilic properties. Ionization seems to be the decisive factor for the incorporation. As all studied PABA derivatives are totally ionized under the experimental conditions, the rates of analogue formation are very similar with the exception of compounds bearing bulky groups in the 2 position. The variance in inhibitory power may therefore either be due to differences in the ability of the analogues to serve as metabolites or to competition with PABA.

4-Aminobenzoic Acid↗