Catabolism of 2,7-dichloro- and 2,4,8-trichlorodibenzofuran by Sphingomonas sp strain RW1.

Due to their physicochemical and toxicological properties, polychlorinated dibenzofurans are regarded as a class of compounds providing reason for serious environmental concern. While the nonhalogenated basic structure dibenzofuran is effectively mineralized by appropriate bacterial strains, its polychlorinated derivatives are not. To elucidate the ability of the strain Sphingomonas sp RW1 to metabolize some of these chlorinated derivatives, we performed turnover experiments using 2,7-dichloro- and 2,4,8-trichlorodibenzofuran. As indicated by the oxygen-uptake rates determined for these two chlorinated dibenzofurans, Sphingomonassp RW1 can catabolize these chlorinated dibenzofurans yielding small quantities of oxidation products, which we isolated and subsequently characterized employing GC/MS and (1)H- as well as (13)C-NMR spectroscopy. In the case of 2,7-dichlorodibenzofuran, two metabolites accumulated, which we identified as 6-chloro- and 7-chloro-2-methyl-4H-chromen-4-one. The single metabolite isolated from the turnover experiments performed with 2,4,8-trichlorodibenzofuran was unequivocally identified as 6,8-dichloro-2-methyl-4H-chromen-4-one.

[Continuous-wave Doppler ultrasound in the 2d and 3d trimester of pregnancy--normal values]. / CW-Dopplersonographie im 2. und 3. Schwangerschaftstrimenon--normalwerte.

Based on 427 patients with uneventful pregnancies and deliveries standard rates were established for the resistance index (RI) and the pulsatility index (PI) of the uterine, arcuate, and umbilical arteries. Percentiles, above all the 90th percentile, are more suitable localisation gauge than are standard deviations. In the observation period, i.e. from 18th to 42nd week of gestation, neither resistance nor pulsatility Index in the utero-placental compartment proved to be dependent on gestational age to any significant degree. By contrast, the umbilical artery showed a definite linear relation between the indices measured and gestational age. If the heart rates are in physiological ranges no clinically relevant effects of the heart rate on the measurement results were observed in either the maternal or the foetal compartment.

[Reproducibility of continuous wave Doppler studies in pregnancy]. / Reproduzierbarkeit von continuous-wave Doppleruntersuchungen in der Schwangerschaft.

The inter- and intraobserver variability of Doppler flow velocimetries of uterine, arcuate and umbilical arteries was studied using a 4 MHz continuous wave system in the second and third trimester of pregnancy. There was no significant variation in indices used to characterize the maximum frequency outline of waveforms of uteroplacental and umbilical arteries neither when two observers examined the same patient nor the examination was performed several times on the same day or over a 24 hour period by the same observer. In uteroplacental and umbilical arteries continuous wave measurements are highly accurate and are not inferior to the more expensive pulsed Duplex systems.