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Biomedical subjects

H Spielmann

Publications and source records attributed to H Spielmann.

At least 91 records · Page 5Linked to original sources
PubMed1975

Lactate dehydrogenase X: effects of antibody on mouse gametes but not on early development.

A rabbit antiserum specific for LDH-X, the spermatozoal form of mouse lactate dehydrogenase, was prepared. This antiserum had no effect on fertility of female mice when injected before or after insemination. Similarly, there was no toxicity to the embryo when high concentrations of the antiserum were added to cultures of 2-cell and 8- to 16-cell embryos. There was, however, a moderate inhibitory effect on fertilization in vitro, which may be attributable to a direct action of antiserum to LDH-X on sperm.

Animals↗
PubMed1975

Gel isoelectric focusing of mouse lactate dehydrogenase: heterogeneity of the isoenzymes A4 and X4.

LDH of mouse organs (including testis) was investigated by isoelectric focusing in polyacrylamide gels. The number of LDH bands in this pattern considerably exceeds the five (six in testis) of the standard electrophoretic pattern. An attempt was made to identify these bands as tetrameric isoenzymes formed by random association of different subunits. This included isoelectric focusing of purified LDH A, B, and X, two-dimensional separation of LDH, urea treatment of LDH, staining with specific substrates, and comparison of different organs. Further experiments were performed to exclude artifacts possibly produced by the isoelectric focusing technique. Different strains of mice were also investigated. The results demonstrate that in addition to the common five LDH bands (A4-B4) one set of five bands is formed by LDH A (A41-A42) and another one by LDH X (X 41-X42). Moreover, an unusual band was found which has a lower molecular weight and no affinity to the other isoenzymes. The data suggest that the heterogeneity of the LDH pattern revealed by isoelectric focusing arises from post-transcriptional events rather than from a number of additional genes.

Animals↗
PubMed1975

Different patterns of energy metabolism in the rat and mouse zygate.

The development of rat zygotes in vitro to the two-cell stage occurred if lactate, phosphoenolpyruvate (PEP), pyruvate or oxaloacetate were present in the media. When rat and mouse zygotes were cultured in the same droplet of medium containing lactate or PEP, mouse zygotes did not develop to the two-cell stage but the rat zygotes cleaved.

Animals↗
PubMedDate not supplied

Embryotoxicity of stable isotopes and use of stable isotopes in studies of teratogenetic mechanisms.

Experiments on teratogenic effects of stable isotopes from our own and other laboratories are evaluated. In the first series of investigations, the enrichment of the stable isotope 13C derived from U-13C-glucose was studied in mouse embryos at various stages of development, including limb buds in organ culture. Preimplantation mouse embryos incubated in vitro in 13C-enriched medium for 48 hours showed normal development during subsequent differentiation in vitro and also in vivo after embryo transfer to faster mothers. These embryos were 15% to 20% enriched in 13C. Administration of U-13-C-glucose to pregnant mice during organogenesis led to an increase of the absolute 13C content of the embryo for several days after the end of isotope administration, whereas the enrichment in maternal tissue decreased. No alterations of embryonic development were detected due to stable isotope enrichment. Development of cultured mouse limb buds was unaffected by incubation with 82 mol% U-13C-glucose as judged from morphologic and biochemical criteria. The second part of the article describes the value of deuterium-labeled drugs as probes into the mechanism of activation of teratogenic metabolites. A comparison of the pharmacokinetics as well as the teratogenicity between cyclophosphamide and some specific deuterium-labeled analogues showed that the isotope effect observed can be related to a particular metabolic pathway crucial for teratogenic activation by this drug.

Animals↗
PubMedDate not supplied

Cytotoxic and genotoxic effects of bromodeoxyuridine during in vitro labelling for sister-chromatid differentiation in preimplantation mouse embryos.

Exposure of preimplantation mouse embryos in culture to bromodeoxyuridine (BrdU) in the concentration range of 10(-9) to 2 x 10(-6) M allows sister-chromatid differentiation at the morula and blastocyst stage. The same BrdU concentrations induced no chromosomal aberrations, but a prolongation of the cell cycle and an increase of the SCE frequency. Even at the lowest BrdU concentration for sister-chromatid differentiation (10(-9) M the background level for SCE was found to be significantly higher in early embryos than in fetal or adult tissues of the mouse. Therefore, the high SCE frequency seems to be characteristic of undifferentiated embryonic cells. Methodological recommendations are also given for SCE assay in preimplantation mouse embryos.

Animals↗
PubMedDate not supplied

Permanent embryonic germ cell lines of BALB/cJ mice--an in vitro alternative for in vivo germ cell mutagenicity tests.

To offer a sensitive and predictive in vitro method to assess germ cell mutagenicity, we established primordial germ (PG) cell-derived permanent female and male embryonic germ (EG) cell lines of the mouse (strain BALB/cJ). The differences in developmental sensitivity of EG cells and differentiated fibroblast cells of the mouse cell line 3T3 to genotoxicants were tested comparatively under identical test conditions. Cytotoxicity assay was measured by the MTT test and genotoxic effects were determined by sister chromatid exchanges (SCE) rates induced by standard reference mutagens. Both methods are used to assign the chemicals to two classes of in vivo reproductive toxicity, non- and strongly genotoxic to germ cells. Applying linear discriminant analysis, a biostatistical prediction model (PM) was developed for the female cell line EG(3). This procedure identified a single variable, the Ig(SCE(200)EG(3)) as the statistically significant concentration related increase of 200% in the mean number of SCEs per metaphase spread after 3 h of exposure to be sufficient for separation into the classes: non- and strongly genotoxic to germ cells. Applying this PM to the training set of five genotoxic and three non-genotoxic test chemicals, 100% correct classifications were obtained.

3T3 Cells↗
PubMedDate not supplied

Lessons learned from validation of in vitro toxicity test: from failure to acceptance into regulatory practice.

As no scientific approach or regulatory guidelines existed for the experimental validation of in vitro toxicity tests, in 1990 a US/European validation workshop agreed in Amden (Switzerland) on a simple definition of the validation process. Several international validation studies failed, although they were conducted according to these recommendations. Taking into account the lessons learned from this experience, a second validation workshop was held by ECVAM in Amden in 1994 to develop a more precisely defined validation concept. Prevalidation and the development of biostatistically defined prediction models were added as essential elements to the validation process. In 1995/1996 the ECVAM validation procedure was officially accepted by EU member countries and at the international level by the US regulatory agencies and the OECD. The improved validation concept was immediately introduced into ongoing validation studies. In 1996 the ECVAM/COLIPA validation study of the in vitro phototoxicity test, which was conducted according to the ECVAM/OECD validation concept, was finished successfully and in 1998 a supporting study on UV-filter chemicals was undertaken. In 1998 the 3T3 NRU PT in vitro phototoxicity test was the first experimentally validated in vitro toxicity test that was recommended for regulatory purposes by ESAC, the ECVAM Scientific Advisory Committee, and by the DG ENV of the EU Commission. Meanwhile, two in vitro skin corrosivity tests have successfully been validated by ECVAM. Finally, in June 2000 the three experimentally validated tests were accepted by EU member states for regulatory purposes as the first in vitro toxicity tests. In addition, ECVAM has funded a successful validation study of three in vitro embryotoxicity tests, which was conducted in 12 European laboratories and finished in July 2000. The three tests validated in this study were the whole embryo culture (WEC) test applied to rat embryos, the micromass (MM) test employing primary cultures of dissociated mouse limb bud cells and the mouse embryonic stem cell test (EST). Examples will be given of successful validation studies during the past decade with particular reference to in vitro toxicity tests that were evaluated for regulatory purposes either by the US validation centre ICCVAM or ECVAM in the fields of sensitisation, phototoxicity and embryotoxicity

Animal Testing Alternatives↗
PubMedDate not supplied

Regulatory use of (Q)SARs in toxicological hazard assessment strategies.

In 2001, the European Commission published a policy statement ("White Paper") on future chemicals regulation and risk reduction that proposed the use of non-animal test systems and tailor-made testing approaches, including (Q)SARs, to reduce financial costs and the number of test animals employed. The authors have compiled a database containing data submitted within the EU chemicals notification procedure. From these data, (Q)SARs for the prediction of local irritation/corrosion and/or sensitisation potential were developed and published. These (Q)SARs, together with an expert system supporting their use, will be submitted for official validation and application within regulatory hazard assessment strategies. The main features are: two sets of structural alerts for the prediction of skin sensitisation hazard classification as defined by the European risk phrase R43, comprising 15 rules for chemical substructures deemed to be sensitising by direct action with cells or proteins, and three rules for substructures acting indirectly, i.e., requiring biochemical transformation; a decision support system (DSS) for the prediction of skin and/or eye lesion potential built from information extracted from our database. This DSS combines SARs defining reactive chemical substructures relevant for local lesions to be classified, and QSARs for the prediction of the absence of such a potential. The role of the BfR database, and (Q)SARs derived from it, in the use of current and future (EU) testing strategies for irritation and sensitisation is discussed.

Animal Testing Alternatives↗