Biomedical subjects

S Buntenkötter

Publications and source records attributed to S Buntenkötter.

At least 19 recordsLinked to original sources

PubMed1996

[Richard Völker and the scientific film (short documentary report)].

In a brief documentary report the role of the scientific teaching film is described. In this context Richard VOLKER is appreciated as film author.

Audiovisual Aids↗

PubMed1994

Effects of static and time-varying (50-Hz) magnetic fields on reproduction and fetal development in rats.

Mated Wistar rats were chronically exposed to a static magnetic field (MF) from day 1 to day 20 of pregnancy. Flux density of the MF was 30 mTesla (mT), i.e., within the range of exposures of operators of magnetic resonance imaging (MRI) devices. For comparison with effects of this static field, a time-varying (50-Hz) MF of the same flux density was used. In both experiments, i.e., static or 50-Hz MF exposure, sham-exposed groups of dams served as controls. On day 20, the dams were sacrificed for reproductive and teratological assessment. The litters were evaluated for numbers of implantations, fetal deaths and resorptions, gross external, visceral, and skeletal malformations, and fetal weights. No adverse effects were seen in the dams during MF exposure. The mean number of living fetuses per litter was significantly decreased in the group with static MF exposure, but not the group with 50-Hz MF exposure. Further differences between the two types of field exposure were observed with respect to minor (skeletal) fetal anomalies which were increased in the 50-Hz but not the static MF group. No serious malformations were seen in any group. In both MF-exposed groups, increased skeletal ossification was found, possibly indicating an accelerated prenatal development. In a second experiment with static MF (30 mT) in which dams were exposed for the whole period of pregnancy, and postnatal growth and development of offspring were studied, the postnatal growth was significantly enhanced in offspring following their prenatal MF exposure.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1993

Effects of magnetic fields on mammary tumor development induced by 7,12-dimethylbenz(a)anthracene in rats.

A series of epidemiological studies have indicated associations between exposure to magnetic fields (MFs) and a variety of cancers, including breast cancer. In order to test the possibility that MF acts as a cancer promoter or copromoter, four separate experiments have been conducted in rats in which the effects of chronic exposure to MFs on the development of mammary tumors induced by 7,12-dimethylbenz(a)anthracene (DMBA) were determined. Female rats were exposed in magnetic coils for 91 days (24 h/day) to either alternating current (AC; 50 Hz)-MF or direct current (DC)-MF. Magnetic flux density of the DC-MF was 15 mT. Two AC-MF exposures used a homogeneous field with a flux density of 30 mT (rms); one used a gradient field with flux density ranging from 0.3-1 microT. DMBA (5 mg) was administered orally at the onset of MF exposure and was repeated thrice at intervals of 1 week. In each experiment, 18-36 animals were exposed in 6 magnetic coils. The same number of rats were used as sham-exposed control. These control animals were treated with DMBA and were placed in dummy coils in the same room as the MF-exposed rats. Furthermore, groups of age-matched rats (reference controls) were treated with DMBA but housed in another room to exclude any MF exposure due to the magnetic stray field from the MF produced by coils. At the end of the exposure or sham-exposure period, tumor number and weight or size of tumors were determined at necropsy. Results were as follows: In sham-exposed animals or reference controls, the tumor incidence varied between 50 and 78% in the 4 experiments. The average number of mammary tumors per tumor-bearing animal varied between 1.6 and 2.9. In none of the experiments did MFs significantly alter tumor incidence, but in one of the experiments with AC-MF exposure at 30 mT, the number of tumors per tumor-bearing animal was significantly increased. Furthermore, exposure to a DC-MF at 15 mT significantly enhanced the tumor weight. Exposure to a gradient AC-MF at 0.3-1 microT exerted no significant effects. These experiments seem to indicate that MFs at high flux densities may act as a promoter or copromoter of breast cancer. However, this interpretation must be considered only a tentative conclusion because of the limitations of this study, particularly the small sample size used for MF exposure and the lack of repetition of data.

9,10-Dimethyl-1,2-benzanthracene↗

PubMed1993

Exposure of rats to a 50-Hz, 30-mT magnetic field influences neither the frequencies of sister-chromatid exchanges nor proliferation characteristics of cultured peripheral lymphocytes.

The issue of potential carcinogenic effects of extremely low-frequency (50/60-Hz) electric and magnetic fields (EMF) has developed almost completely from epidemiological studies suggesting a link between residential or occupational exposure to EMF and an elevated risk of various cancers. Concerning chromosome-altering effects of EMF, in vitro studies gave ambiguous results and only few in vivo studies have been done. In the present study, we investigated the effect of long-term exposure of rats to a 50-Hz, 30-mT magnetic field (MF) on cell proliferation and frequencies of sister-chromatid exchanges (SCE) in peripheral lymphocytes of rats following exposure to MF for 7 or 28 days. As a positive control, rats were treated with cyclophosphamide. In contrast to cyclophosphamide, MF exposure influenced neither SCE frequencies nor proliferation characteristics of cultured peripheral lymphocytes.

Animals↗

PubMed1993

[80 year constitution of the rectorate of the School of Veterinary Medicine Hannover].

On the July 18th 1993, the School of Veterinary Medicine existed for 215 years. The School named royal "Rossarzneischule" was founded under the direction of the "Oberhofrossarzt" JOHANN ADAM KERSTING by means of the royal order of George III, King of England and Duke of Hannover, in 1778. Shortly afterwards it had expanded to the royal "Thierarznei-Schule" and the School of Veterinary Medicine obtained its present name in 1887. A constitution of the rectorate was obtained in March 31 by royal decree. The inauguration of the first rector, BERNHARD MALKMUS, took place on June 16th in 1913. Up to now, 36 rectors held office at this university. An epilogue of this constitution indicates the early history from 1887-1913. A chronology of the rectors is shown at the end of this paper.

Germany↗

PubMed1985