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Biomedical subjects

H Spielmann

Publications and source records attributed to H Spielmann.

At least 55 records · Page 3Linked to original sources
PubMed1987

Spontaneous and cyclophosphamide-induced sister-chromatid exchanges in diploid and endoreduplicated tetraploid metaphases of preimplantation mouse embryos.

Endoreduplicated tetraploid metaphases could for the first time be induced in preimplantation mouse embryos by culture in the suboptimum medium MEM. In such endomitoses sister-chromatid exchange (SCE) frequency was approximately the same during the first and the second cell cycle. However, when morulae and blastocysts were cultured in the presence of cyclophosphamide metabolites SCE frequency was increased predominantly during the second cell cycle. Compared to diploid metaphases a decreased SCE frequency was found under both conditions of endomitoses induction, which may be related to DNA-repair processes.

Animals↗
PubMed1987

Test guideline. Behavioral toxicity testing in animal experiments according to section 9, para. 1, No. 2 of the Chemicals Act (Chemikaliengesetz) of the Federal Republic of Germany.

The German Chemicals Act requires that chemicals are tested for behavioral toxicity at stage 2 of the testing procedure, i.e. if more than 1000 annual tons are produced. For this purpose a guideline was developed according to which data on behavioral toxicity are to be collected, which are based on cageside observations during longterm exposure. The protocol covers outer appearance, as well as motor, sensory, autonomic and central nervous system functions. Data are to be reported in tabular form and should be evaluated by taking all aspects of the toxicological profile into account.

Animals↗
PubMed1987

Studies on the embryotoxic risk of exposure to caffeine and ethanol during the preimplantation period in the mouse.

Pregnant mice were exposed before implantation to caffeine and ethanol to determine the dose-response relation for embryolethality during the preimplantation period. For risk estimation the embryotoxicity was evaluated at term and also 24 h after implantation. For ethanol no embryotoxic risk could be detected. Caffeine unexpectedly exhibited a high risk for embryoethality when compared to the maternal LD50. However, when taking into account realistic exposure levels an embryotoxic risk in early pregnancy can be excluded in humans for both caffeine and ethanol.

Animals↗
PubMed1986

[Evaluation of the embryotoxic risk of industrial chemicals in pregnancy].

For the first time exposure levels during pregnancy have been evaluated for industrial chemicals in the German list of "Maximal occupational exposure limits and biological tolerance levels of occupational chemicals 1985" (MAK-Werte-Liste). According to this evaluation only a single substance (methylmercury) is embryotoxic in man, a prenatal risk cannot be excluded for eight chemicals, and 18 chemicals are safe at occupational exposure limits (MAK-Werte). Furthermore, pregnant women should avoid exposure to any of the 112 carcinogenic chemicals of the list and to 26 substances which are under evaluation for embryotoxic properties. Occupational chemicals are subdivided into four pregnancy riskgroups and discussed with respect to prenatal counselling.

Abnormalities, Drug-Induced↗
PubMed1986

Studies on the embryotoxic risk of drug treatment during the preimplantation period in the mouse.

For risk evaluation of exposure to drugs in early pregnancy the dose-response relationship for embryotoxicity was determined in mice during the preimplantation period using cytotoxic drugs (cyclophosphamide, mitomycin, vinblastine) and therapeutic drugs which are embryotoxic in laboratory animals or in humans during organogenesis (diazepam, doxycycline, phenobarbital, rifamycin, tolbutamide). No malformations but only signs of retardation and a dose related increase in the resorption rate could be detected after treatment with some of the drugs at term even at dose levels close to the maternal LD50 (MLD50). A comparison of the embryolethal dose during the preimplantation period (ELD50) with the MLD50 revealed no risk for the therapeutic drugs, a slight risk for mytomycin and vinblastine and an unusually high risk for cyclophosphamide. The ELD50 for all drugs in this study was higher than the embryotoxic doses during organogenesis which is routinely determined for all drugs. It is concluded that for therapeutic drugs additional testing for embryotoxicity during early pregnancy is not required.

Animals↗
PubMed1985

Abnormal chromosome behavior in human oocytes which remained unfertilized during human in vitro fertilization.

Chromosomal abnormalities and abnormal embryonic development have previously been observed after human in vitro fertilization (IVF). Chromosomal abnormalities may arise not only after fertilization but even earlier during meiotic maturation of human oocytes in culture. Since chromosomal analysis is simple in oocytes during meiotic maturation, the chromosomal status was analyzed in oocytes which remained unfertilized in a human in vitro fertilization program. In 50 fertilization attempts the chromosomes of 62 unfertilized oocytes could be analyzed; 45 of them were in the process of meiotic maturation. In three oocytes two small polar bodies were observed 16-18 hr after insemination in the absence of fertilization. In one oocyte abnormal chromosome behavior was found during the first meiotic division, and in four oocytes during metaphase of the second meiotic division. These data suggest that chromosomal analysis of unfertilized oocytes in human IVF may improve the understanding human oocyte maturation and fertilization.

Chromosome Aberrations↗
PubMed1985

Development and sister chromatid exchange of mouse morulae and blastocysts cultured in rat serum containing active metabolites of cyclophosphamide.

To establish an in vitro test system in which sera from animals treated with various chemicals can be tested for embryotoxic effects during the preimplantation period, mouse morulae and blastocysts were cultured in the presence of rat serum (RS) from animals which had been treated with cyclophosphamide (CPA). Development during in vitro culture for 96 h, cell number, chromosomal aberrations and sister chromatid exchange (SCE) were the end-points tested in exposed embryos. SCE frequency was the most sensitive parameter, indicating embryotoxic effects in preimplantation mouse embryos after only 1 h of exposure to RS-CPA.

Animals↗
PubMed1985

[In-vitro-fertilization: chromosome analysis of unfertilized human oocytes].

Chromosomal abnormalities and abnormal embryonic development have been observed after human in vitro fertilisation (IVF). Such investigations are not permitted according to the ethical guidelines approved by the IVF team in Berlin ("Berliner Modell"). However, the chromosomal status was studied in oocytes which remained unfertilised in a human IVF programme. In 50 fertilisation attempts the chromosomes of 62 oocytes could be analysed. 45 of the oocytes were in the process of meiotic maturation. One of these showed abnormalities in the first meiotic division and seven during the second meiotic division. After fertilisation in addition to normal embryos, all of which were transferred to the mother, three embryos were triploid and six oocytes were fragmented. The results prove that in human IVF chromosome abnormalities can occur in oocytes already before fertilisation. The importance of the results for later stages of embryonic development is discussed.

Chromosome Aberrations↗
PubMed1984

Changes of the adenine ribonucleotide content during preimplantation development of mouse embryos in vivo and in vitro.

The amount of ATP, ADP and AMP and also the adenylate energy charge and the ATP/ADP ratio were determined in preimplantation mouse embryos (strain NMRI) in vivo. The ATP content decreased from 0.64 pmol at fertilization to 0.21 pmol in late blastocysts. ADP decreased from 0.1 pmol in the zygote to 0.06 pmol in 4-8-cell embryos and increased again to 0.15 pmol in late blastocysts. AMP changed considerably at the 1-cell and the 2-cell stage and increased from 0.04 to 0.2 pmol between the 4-cell and the late blastocyst stage. These developmental changes between fertilization and implantation result in a continuous decline of the total amount of adenine ribonucleotides (from 0.79 to 0.64 pmol), of the adenylate energy charge (from 0.87 to 0.45) and of the ATP/ADP ratio (from 6.4 to 1.4). In C57BL embryos developing to the 2-cell stage in vivo or in vitro there was a decrease in ATP content, as in NMRI embryos in vivo whereas the ATP content remained unchanged in NMRI embryos during culture to the 2-cell stage (no further development in vitro). In blastocysts cultured for 24 h in media supporting differentiation during implantation (MEM and NCTC-109) the content of ATP and ADP increased but AMP remained constant. The total adenine ribonucleotide content rose to 1 pmol and the ATP/ADP ratio and adenylate energy charge remained unchanged. After 48 h of culture in the two media to late blastocysts there was a decrease in ATP, an increase in AMP and a decline in adenylate energy charge and ATP/ADP ratio, as occurs in vivo.

Adenine Nucleotides↗
PubMed1983

Normal adenylate ribonucleotide content in mouse embryos homozygous for the t12 mutation.

The recently improved firefly luciferase assay was used to determine ATP, ADP or AMP in single preimplantation mouse embryos from crosses yielding lethal t12/t12 embryos. Normal values of the three adenylate ribonucleotides were found in freshly collected 2-cell and 4-cell embryos and during in vitro culture to the blastocyst stage. A decrease in adenylate ribonucleotide content was seen in putative t12/t12 embryos only when they were degenerating.

Adenine Nucleotides↗
PubMed1982

Teratogenic effects of cyproterone acetate and medroxyprogesterone treatment during the pre- and postimplantation period of mouse embryos. I.

Pregnant mice were treated with a single subcutaneous injection of either cyproterone acetate (CA) or medroxyprogesterone acetate (MPA). In the first experiment the animals received 5-900 mg/kg of the hormone before implantation (day 2 of pregnancy). CA treatment on day 2 caused a dose-dependent decrease in fetal weight and a significant dose-dependent increase in the rates of cleft palate and urinary tract abnormalities. Exencephaly and heart abnormalities were also significantly more frequent, but this increase was not dose-dependent. MPA treatment on day 2 was followed by sporadic increases in dead and resorbed fetuses, a decrease in fetal weight and an increase in the rates of cleft palate, and malformed or abnormally developed fetuses. None of these effects, however, was dose-dependent. In the second experiment the mice were given one single injection (30 mg/kg) of CA or MPA on any one of days 1-12 of gestation. Treatment with CA on one day between days 1 and 12 revealed that the specific sensitivity for abnormalities of the urinary tract was on days 5 and 6, for the respiratory tract on days 8 and 9, and for cleft palate on days 10 and 11. Treatment with MPA on one day between days 1 and 12 only revealed a high rate of respiratory and urinary tract abnormalities on day 9. After treatment with MPA cleft palate was again significantly more frequent in all treated groups, however, days of peak sensitivity were not detected. The long half-life of CA (60 hours) explains the teratogenic effect of high doses of this progestin after treatment on day 2 and also the pattern of abnormal development found after treatment with a single dose of CA on one of the days between day 1 and day 12.

Abnormalities, Drug-Induced↗
PubMed1982

Teratogenic effects of cyproterone acetate and medroxyprogesterone treatment during the pre- and postimplantation period of mouse embryos. II. Cyproterone acetate and medroxyprogesterone acetate treatment before implantation in vivo and in vitro.

The study was performed to investigate direct embryotoxic effects of maternal progestin treatment during the preimplantation period. In the first experiment pregnant mice received a single subcutaneous injection of either cyproterone acetate (CA) or medroxyprogesterone acetate (MPA) on day 2 of pregnancy (5-600 mg/kg). In a second experiment four-cell embryos were exposed to CA or MPA in vitro (3 or 30 micrograms/ml medium). Our results revealed: (1) After maternal treatment the number of live embryos was reduced after the highest CA dose. Development into blastocysts was inhibited in a dose-related manner after CA but not after MPA. The number of cells in morulae, blastocysts, and of the inner cell mass (ICM) of late blastocysts was not affected. (2) When morulae and blastocysts were cultured in vitro after maternal treatment, hatching, attachment, and trophoblast outgrowth were inhibited after high doses, but development and differentiation of the ICM were inhibited even after low doses. (3) Application of 30 micrograms/ml of CA or MPA in vitro was directly embryolethal. Three micrograms/ml did not affect development into blastocysts, but ICM development and differentiation were again inhibited during subsequent culture in hormone-free medium. (4) Qualitative protein synthesis was altered in morulae and blastocysts 24 hours after maternal CA treatment. According to our results high doses of progestins are embryotoxic before implantation, low doses have delayed effects on embryonic development that are particularly evident after implantation in vitro.

Animals↗
PubMed1982

Mutagenic, teratogenic and pharmacokinetic properties of cyclophosphamide and some of its deuterated derivatives.

To elucidate which metabolic pathway leads to the ultimate mutagenic and teratogenic metabolite of cyclophosphamide (CPA), the mutagenicity in vitro as well as the teratogenicity in vivo and the pharmacokinetics of CPA and several deuterated analogs (5,5-d2-CPA, 4,4-d2-CPA and 4,4-6,6-d4-CPA) were compared. 5,5-d2-CPA was less mutagenic (isotope effects between 1.7 and 12.3 were found for sister-chromatid exchanges and structural chromosomal aberrations in CHO cells and in the Ames test) and less teratogenic (deuterium isotope effect between 2 and 3) than CPA and the other deuterated analogs. Because the concentrations of 5,5-d2-CPA in pregnant mice and their embryos were equal to or even exceeded those of CPA and the other deuterated analogs, a particular metabolic pathway involving a fission of the C-D or C-H bond on the C-5 rather than the parent drug must be responsible for the isotope effect observed. It had previously been shown (Cox et al., 1976) that the 5,5-d2-CPA has a decreased anti-tumor activity in vivo (isotope effect 7-13) which was accompanied by a decreased formation of phosphoramide mustard and acrolein in vitro (isotope effect 5.3). Our results suggest that phosphoramide mustard is an important proximate metabolite of CPA with regard to the mutagenicity and teratogenicity of the drug. These results show for the first time that labeling of drugs with stable isotopes offers a promising approach to the study of the mechanism of the mutagenic and teratogenic actions of drugs.

Animals↗