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H Merten

Publications and source records attributed to H Merten.

4 recordsLinked to original sources
PubMed2000

[Continuous bone distraction with the help of a microhydraulic cylinder].

Distraction osteogenesis of the mandible is one treatment option in mandibular hypoplasia. Usually, a non-continuous distraction mode is applied. The aim of the present study was to establish continuous bone distraction using a microhydraulic cylinder. Using a submandibular approach, the mandible was dissected subperiostally on one side in four mini-pigs; corticotomy was performed and the microhydraulic cylinder fixed with two bicortical screws. The hydraulic tube was connected with an automatic hydropneumatic injector system. Following 7 days at rest, a continuous distraction of 1.5 mm per day was performed for 14 days. After 2 and 4 weeks postoperatively, the animals were killed and X-rays taken. The mandible was then removed en bloc and microscopic evaluation of the sections was performed. The microhydraulic cylinder was easy to apply and to handle. The continuous stimulus did induce direct mineralisation of longitudinal oriented collagenous fibre bundles. Bony regeneration seems to be accelerated, which might reduce the postoperatively stabilizing phase.

Animals↗
PubMed1993

Genotoxicity assessment of waste products of aluminum plasma etching with the SOS chromotest.

We evaluated 36 characteristic waste products from the plasma etching of aluminum for genotoxicity with the SOS chromotest. The majority of the samples showed genotoxic activity in tester strain Escherichia coli PQ37 without metabolic activation using S9 mix. In the presence of S9, a deactivation of the samples was regularly observed. Comparable studies with the Salmonella/microsome (Ames) test using tester strains Salmonella typhimurium TA98 and TA100 indicated actual mutagenicity of waste products. Gas chromatograms of the organic constituents of all waste products were performed in parallel with the genotoxicity assays. In contrast to the similarity of the peak patterns of all chromatograms, the biological effects of individual waste samples showed large differences. Information on chemical composition and the SOS chromotest results of a representative sample recovered over a period of 2 years is given. For this sample, the influences of sample preparation and cytotoxic matrix effects on the test parameters are also shown.

Aluminum↗
PubMed1993

Genotoxicity studies in semiconductor industry. 1. In vitro mutagenicity and genotoxicity studies of waste samples resulting from plasma etching.

Solid waste samples taken from the etching reactor, the turbo pump, and the waste air system of a plasma etching technology line in semiconductor production were studied as to their genotoxic properties in a bacterial repair test, in the Ames/Salmonella microsome assay, in the SOS chromotest, in primary mouse hepatocytes, and in Chinese hamster V79 cell cultures. All three waste samples were found to be active by inducing of unscheduled DNA-synthesis in mouse hepatocytes in vitro. In the bacterial rec-type repair test with Proteus mirabilis, waste samples taken from the turbo pump and the vacuum pipe system were not genotoxic. The waste sample taken from the chlorine-mediated plasma reactor was clearly positive in the bacterial repair assay and in the SOS chromotest wit Escherichia coli. Mutagenic activity was demonstrated for all samples in the presence and absence of S9 mix made from mouse liver homogenate. Again, highest mutagenic activity was recorded for the waste sample taken from the plasma reactor, while samples collected from the turbo pump and from the waste air system before dilution and liberation of the air were less mutagenic. For all samples chromosomal damage in V79 cells was not detected, indicating absence of clastogenic activity in vitro. Altogether, these results indicate generation of genotoxic and mutagenic products as a consequence of chlorine-mediated plasma etching in the microelectronics industry and the presence of genotoxins even in places distant from the plasma reactor. Occupational exposure can be expected both from the precipitated wastes and from chemicals reaching the environment with the air stream.

Animals↗