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Biomedical subjects

E T Mystkowska

Publications and source records attributed to E T Mystkowska.

15 recordsLinked to original sources
PubMed2001

Embryotoxicity of magainin-2-amide and its enhancement by cyclodextrin, albumin, hydrogen peroxide and acidification.

BACKGROUND: The channel-forming antimicrobial peptide, magainin-2-amide, interacts preferentially with negatively charged, non cholesterol-containing membranes, including those of sperm, oocytes and cells of pre-implantation embryos. Cyclodextrin and albumin remove membrane cholesterol and together with hydrogen peroxide (H2O2) are potential enhancers of embryotoxicity. METHODS: Two-cell murine embryos were cultured in vitro with magainin-2-amide at a high effective concentration (250 microg/ml) and at subthreshold concentrations (166 and 200 microg/ml). Embryos treated with sub-threshold concentrations of magainin were additionally treated with cyclodextrin, bovine serum albumin or H2O2 or were cultured under acidified conditions. Cell viability was verified with propidium iodide and fluorescein diacetate. RESULTS: The embryotoxic effect of magainin and H2O2 was dose- and time-dependent. Cyclodextrin, H2O2, acidification of the medium, and to a lesser extent albumin, enhanced the embryotoxicity of magainin at sub-threshold concentrations. CONCLUSION: Magainin on its own is highly embryotoxic. Its embryotoxicity is enhanced by cyclodextrin, albumin, H2O2 and acidification. Thus, magainin which has antibacterial, antifungal and antiprotozoal activity may also have a potential role as a contraceptive agent. The harmful effects of various concentrations of the exogenous H2O2 on 2-cell stage mouse embryos are reported here, to the best of our knowledge, for the first time.

Animals↗
PubMed1995

[Draize test and alternative methods for evaluating irritation from chemical substances].

The eye irritancy test in rabbits (Draize test) is currently the method used to evaluate the hazard or safety of chemical substances. To reduce the need for animal testing some new procedures as alternative were elaborated. We present a review of method used as well as evaluation of sensitivity and repeatability of alternative tests applied in laboratories of European Economic Communities.

Animal Testing Alternatives↗
PubMed1992

Hermaphroditism in young mouse chimeras.

Among 23 5-day old mouse chimeras, 11 were sex chimeras. Four of them were hermaphrodites, six were males and one was female. In the gonads of three hermaphrodites fragments of ovarian tissue were very small. Growing oocytes were observed not only in ovotestes but also in testes. The course of transformation of ovotestes into testes is discussed.

Animals↗
PubMed1991

Fourier analysis of the nuclear and cytoplasmic shapes of living two-cell murine embryos.

Living two-cell mouse embryos were flushed out from the oviduct 17, 24 and 36 hours after fertilization in order to obtain cells in the G1S, early G2 and late G2 phases of the second cell cycle. The nuclei of the living cells were stained with Hoechst 33342. The coordinates of the contour shapes of the entire cells (cellular contours) were registered by contour image processing with a TV camera coupled with a computer; the contours of the nuclei were computed by means of a digitizer coupled with the computer. Fourier analysis of the cellular and nuclear contours revealed systematic modifications in the folding of the cells and nuclei in the course of the murine second cell cycle. The progression of cells through the second cell cycle was correlated with an increasing diversification of cellular and nuclear shape, with the diversification being much more pronounced in the nuclear shapes.

Animals↗
PubMed1990

In vivo staining of mouse preimplantation embryos with Hoechst 33342.

Female mice bearing secondary oocytes or preimplantation embryos of various stages were injected with Hoechst 33342 (H 33342), either intravenously or intraperitoneally and sacrificed at various intervals afterward. The dye penetrated through the wall of oviduct and stained the nuclei of its cells as well as mitotic chromosomes of secondary oocytes, the pronuclei of one-cell embryos, and nuclei of blastomeres and polar bodies. The nuclear fluorescence was observed in living cells flushed out of the oviduct as well as in those fixed in oviduct, embedded in paraffin, and sectioned. H 33342 injected in a dose of 10 micrograms/g of body weight failed to interfere with preimplantation development of stained embryos as indicated by the number of blastocysts per mouse and number of cells per blastocyst.

Animals↗
PubMed1987

Modification of cell division by phorbol ester in preimplantation mouse embryos.

2-cell mouse embryos were treated in vitro with a 2 h pulse of phorbol myristate acetate (PMA) at 32nd, 38th and 50th h after hCG, then chased in culture for up to 46 h. Embryos were fixed at various time intervals of chasing, then stained and inspected. Some embryos were carefully inspected with a video recording system, every 1.44s and the cell divisions (cytokinesis) as well as formation of large, single blastomeres, each from two smaller ones, were recorded. PMA pulse let to the suppression of cell divisions. The rate of the suppression was time dependent: with a delay of 0-1, 12 and 18 h between the PMA pulse and time of scheduled cell division about 99, 87 and 44% of 2-cell embryos remained at this stage of development, for at least 10 h, respectively, and 90, 58 and 12% of their blastomeres revealed binuclearity. Since we found that PMA-mediated formation of binuclearity was not the effect of cell fusions, it was assumed that the inhibition of cytokinesis preceded by karyokinesis was responsible for binuclearity. PMA effect on cell divisions was reversible. PMA-treated embryos revealed formation of large, single blastomeres, each from two smaller ones. If cell division appeared after PMA pulse, in about 52% of 3- to 6-cell embryos, the large blastomere formation was recorded in the course of the subsequent 38 h. Large blastomere formation was concluded to be the result of either cell fusion or reversion of incompleted cytokinesis brought about by PMA.

Animals↗
PubMed1979

Factors regulating the degree and extent of experimental chimaerism in the mouse.

The degree of chimaerism of the coat, bone marrow and cornea in mouse chimaeras obtained by aggregation of an albino inbred embryo of A strain with an A X CBA-T6T6 hybrid was investigated. Out of 21 individuals born, 18 were chimaeras. Statistically significant correlation has been demonstrated between chimaerism of the coat, bone marrow and the cornea. The contribution of the two components appears to be affected by two factors: first, variable participation of the two components inthe embryonic ectoderm of the chimaeric egg cyclinder, and second, the rate of proliferation of the two cell lines. A photometric method is described which permits the quantitative evaluation of coat chimaerism. The method is sensitive and reliable.

Animals↗
PubMed1976

Implantation and early postimplantation development of the bank vole Clethrionomys glareolus, Schreber.

The development of the bank vole Clethrionomys glareolus is described from implantation to the formation of the foetal membranes. The embryonic development of this species combines features of primitive rodent species, for example Geomys bursarius and highly specialized ones, for examples Mus musculus. The egg-cylinder is formed by invagination into the blastocoelic cavity of the inner cell mass and polar trophoblast overlying it; this resembles in many respects the early stages of development of primitive species. The fully formed egg-cylinder, however, resembles that of the mouse and the formation of foetal membranes is also similar to that in Muridae. It is concluded that in the bank vole and also in other rodents, the extra-embryonic ectoderm of the egg-cylinder is derived from the polar trophoblast rather than from the inner cell mass.

Animals↗
PubMed1975

Preimplantation development in vivo and in vitro in bank voles, Clethrionomys glareolus, treated with PMSG and HCG.

Ovulation can be induced in the bank vole by PMSG and HCG and takes place 9 1/2 to 11 1/2 hr after administration of HCG. The number of eggs obtained varied from 1 to 30 (average 9.3). The highest ovulation rates were observed when PMSG and HCG were administered 41 to 43 1/2 hr apart. The embryos attained the blastocyst stage 96 hr after HCG injection. Bank vole eggs can be cultured in chemically defined media beginning with the eight-cell stage; only 25% of four-cell eggs developed to blastocysts in vitro.

Animals↗
PubMed1975

Development of mouse-bank vole interspecific chimaeric embryos.

One bank vole (Clethrionomys glareolus) embryo and two mouse embryos were combined at the 8- to 16-blastomere stage and cultured in vitro for 33-47 h. In 66% of cases single regular blastocysts were formed. The chimaeric composition of blastocysts was confirmed karyologically. Out of the 222 blastocysts transplanted to 49 pseudopregnant mouse recipients, a total of 52 implantations were found in 20 recipients. Among the 52 implantations, 14 contained embryos and the remaining were resorptions. The majority of embryos were abnormal and fell into two categories: (1) groups of cells surrounded by Reichert's membrane and lying freely in a cavity filled with giant trophoblastic cells, (2) small and retarded egg-cylinders usually composed of endoderm and ectoderm only, and containing a proamniotic cavity. The ectoplacental cone of these embryos was poorly developed or lacking altogether. Two normal-looking embryos were recovered on the 9th and 10th day (4-somite and ca. 12-somite stage). Chimaerism of the younger embryo was confirmed karyologically. No evidence of chimaerism was available in the case of older embryo which was examined histologically. Thirteen implantations examined between 11th and 17th day contained only resorptions. It is suggested that the main cause of the heavy mortality of chimaeric embryos is the profound difference in the course of embryogenesis of these two species immediately following implantation.

Animals↗