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PubMed1992

Shigella-type pathomechanism in the "mouse model".

A strain of Escherichia coli K-12 carrying the 140-Megadalton virulence plasmid of the enteroinvasive E. coli--J53(pSPl)--showed high virulence in the "mouse model", in chick embryos, but not in the Serény test. It expresses the outer membrane proteins thermoregulatedly, encoded also by the virulence plasmid. In orally infected streptomycin-pretreated mice this strain infects only the large bowel, shows adherence to the epithelial surface, but in its first step preferentially to the mucus excreted by the goblet cells. Epithelial penetration and intracellular multiplication occurs with a characteristic localization of bacteria in the depth of crypts. Consequence of the infection is degeneration of the epithelial surface, its denudation.

Animals↗
PubMedDate not supplied

[Expression of cathepsins D and L during neoplastic transformation of fibroblasts].

Study of the expression of the aspartyl cathepsin D-like and cysteine cathepsin L-like proteinases was carried out on a model system of rat embryo fibroblasts. The model system employed makes it possible to distinguish two discrete successive stages of transformation in vitro: immortalization and tumorigenic transformation. The dynamics of expression and subcellular distribution of proteinases throughout the transformation process was followed. It was shown that in immortalized and transformed cells the activities of the aspartyl and cysteine proteinases were expressed to a variable degree and the expression was dependent on the time of cell cultivation. The increase in both the aspartyl cathepsin D-like proteinase and cysteine cathepsin L- and B-like proteinase activities was correlated with the stage of fibroblast transformation. At all stages studied of transformation, the major part of cathepsin L-like proteinase activity was localized within the cell, while among secreted proteinases the cathepsin D-like proteinase was apparently predominant. It was found that the secreted cathepsin D-like proteinase in all cell cultures studied was complexed with the inhibitor.

Animals↗
PubMed1988

Ovariectomized steroid-treated mares as embryo transfer recipients and as a model to study the role of progestins in pregnancy maintenance.

Embryo transfer into ovariectomized steroid-treated mares was used as a model to evaluate various progestin/estradiol treatments and to determine the level of progesterone necessary for the maintenance of pregnancy in mares. Once a donor mare was in estrus and had a >/=35 mm follicle, an ovariectomized recipient was selected and assigned to one of three groups: 1) 1 mg estradiol (E(2)) was injected subcutaneously daily until the donor mare ovulated; on the day of the donor mare's ovulation, daily intramuscular injections of 300 mg progesterone (P4) were commenced and continued until the end of the experiment (Day 35); 2) E(2) and P4 treatments were identical except E(2) was continued daily until Day 20; and 3) The same E(2) treatment as Group 1, 0.044 mg altrenogest per kilogram body weight were administered daily until Day 35. Embryos were recovered 7 d after the donor mare's ovulation and were transferred via surgical flank incision. Twenty additional embryos (controls) were transferred into intact recipients that ovulated 1 d before to 3 d after the donor. Pregnancy rates did not differ (P>0.05) among groups at Days 14 or 35. Pregnancy rates at Day 35 for mares administered injectable P4 (70%) were identical to those given altrenogest. Overall, pregnancy rates for ovariectomized-progestin treated recipients (28 of 40, 70%) were similar (>0.05) to that of intact mares (16 of 20, 80%). Dose of P4 was decreased in Groups 1 and 2 to 200 mg (Days 35 to 39), 100 mg (Days 40 to 44), 50 mg (Days 45 to 49) and 0 mg (>/=Day 50). Blood samples were collected once on Days 34, 35, 39, 40, 44, 45, 49 and 50 and assayed for P4. Dose of altrenogest was decreased to 0.022, 0.011, 0.0055 and 0 mg per kilogram body weight at Days 35 to 39, 40 to 44, 45 to 49 and >/=50. Number of mares in Groups 1 and 2 that lost their pregnancy while given 200, 100, 50 or 0 mg P4 was 0, 2, 8 and 4, respectively. Doses of 0.022, 0.011, 0.0055 and 0 mg altrenogest per kilogram body weight resulted in 0, 6, 4 and 3 mares aborting. Fetal death did not occur until concentrations of P4 decreased below 2.56 ng/ml 24 h after injection.

Journal Article↗
PubMed2005

Algorithm to predict assisted reproductive technology pregnancy outcome reveals minimal embryo synergy.

A mathematical model was developed to calculate the implantation probability for individual embryos based on the pregnancy outcome of in vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI) cases with multiple embryos transferred. This model was used to calculate implantation probabilities of embryos of 31 morphological types using the outcome of 1,200 IVF/ICSI cases. The algorithm was validated by comparing the calculated pregnancy probability and multiple pregnancy probability with the actual outcome of 281 separate IVF/ICSI cases. Finally, an estimation of embryo synergy was calculated.

Algorithms↗
PubMedDate not supplied

[Model studies of the effect of structural changes in cleaving embryo on electrical parameters of cellular interactions].

Two models of the embryo developing from one initial cell by cleavage division are considered. Equivalent electrical schemes were constructed, changes in electrical coupling coefficient (Kec) and input resistance (ri) of the embryos during cleavage were estimated. Considerable influence of cleavage-related changes of membrane parameters on Kec and ri appears at the first five--ten cleavages and essentially depends on the ratio of contact and incontact membrane resistances. A comparison of the estimated curves of Kec and ri with experimental ones (loach and axolotl embryos) has shown that the model curves with the ratio rm/rc equalling 100 and 1000 are very close to the real ones.

Animals↗
PubMed1994

In vitro treatment of embryos with epidermal growth factor improves viability and increases the implantation rate of blastocysts transferred to recipient mice.

OBJECTIVE: Our purpose was to study, by means of a mouse embryo donation model, the possible role of epidermal growth factor in the development of preimplantation embryos. STUDY DESIGN: Seven blastocysts developed either in vivo or in vitro, with or without treatment with epidermal growth factor, were transferred to a uterine horn of pseudopregnant recipient mice on day 3 (the presence of a vaginal plug indicated day 1 of pseudopregnancy). Recipients were killed on day 8 of pseudopregnancy, and the number of implantation sites was counted. RESULTS: The implantation rate in recipient mice of in vitro-cultured blastocysts was significantly lower than that of embryos grown in vivo (i.e., 57.1% vs 84.2%) (p < 0.001). Treatment of embryos in vitro with epidermal growth factor, 10 ng/ml, effectively prevented a decrease in implantation rate (77.9%). CONCLUSION: Epidermal growth factor may play a stimulatory role in the development of the preimplantation mouse embryo.

Animals↗
PubMed2004

[Establishment of model human stem cell of transplantation into myocardium of chick embryos].

OBJECTIVE: To establish an animal model of human stem cell transplantation into myocardium in chick embryos. METHODS: Hoechsst 33,258 labeled human primordial germ cells (hPGC) were microsurgically injected into the myocardium of 633 chick embryos of 3-4 days development. Ten days after, the hearts were isolated from the 94 surviving chick embryos, embedded, and sliced. In situ hybridization (ISH) with human specific DNA Alu probe was conducted on the sections with fluorescence to detect the existence of transplanted PGC. Immunohistochemistry with human-myocardium-specific antibody cTnT was conducted on the adjacent sections to observe the differentiation of human myocardial cells. RESULTS: ISH showed that PGC were detected in the myocardium of chick embryos 10 days post-operationally. Immunohistochemistry showed that the myocardium added with antibody in adjacent sections was cTnT-positive and the myocardium untreated with antibody was cTNT-negative. Successful cell transplantation occurred in 15.3% +/- 2.4% of chick embryos. CONCLUSION: Establishment of an animal model of cell transplantation of human stem cells into myocardium in chick embryos is feasible.

Animals↗
PubMed2003

Endometrial receptivity: selective adhesion competence of rabbit uterine epithelium for trophoblast but not for various tumor cells.

A modification of an established in vitro model for embryo implantation was used to probe the receptive uterine epithelium for any specificity of interaction with various invasive cells other than trophoblast. Endometrial explants consisting of stroma and epithelium taken from pseudopregnant rabbits were cultured in the presence of progesterone in order to regenerate a complete epithelial lining while maintaining the receptive state. Such precultured fragments were brought into contact with multicellular spheroids of different invasive tumor cell lines from different species. In contrast to the trophoblast of the rabbit blastocyst (previous publication), none of the tumor cell lines was able to adhere to intact epithelium of endometrial fragments nor to penetrate it. The uterine epithelium was also an insurmountable barrier for tumor cell spheroids confronted with the epithelium of fresh complex explants consisting of endometrium and myometrium or for spheroids introduced into the uterine lumen of pregnant/pseudopregnant rabbits at the periimplantation phase. However, all tumor cells were able to adhere to and mostly also to invade into the endometrial stroma when it was exposed artificially, i.e. when the epithelium was removed. These results suggest that the receptivity of rabbit uterine epithelium shows a remarkable selectivity with respect to cell type (trophoblast) and species (rabbit, not human, mouse, or rat).

Animals↗
PubMed1975

[Study of the role of colicins in the formation of microbial association in experiments in chick embryos].

Experiments were conducted on chick embryos; conditions of formation of bacterial cenosis of Shigella sonnei and E. coli were reproduced. The role of colicinogenia in the formation of bacterial cenosis was demonstrated. An accumulation of colicines in high titres (1: 5120- 1:2560) in the chick embryonic cavity was noted in combined or separate cultivation of colicinogenic shigellae and E. coli. An intergenera transmission of the col-factor was traced in experiments on chick embryos. The data obtained served as foundation for recommendation of the accessible and economic model (chick embryos) for the in vivo study of colicinogenia of the enteric bacteria representatives.

Animals↗
PubMed1997

Cryopreservation of oocytes and embryos: use of a mouse model to investigate effects upon zona hardness and formulate treatment strategies in an in-vitro fertilization programme.

Mouse oocytes and embryos were obtained following ovulation induction of (C57B16 x CBA) F1 animals. Zonae pellucidae were exposed to alpha-chymotrypsin in phosphate-buffered medium (PB1) supplemented with 3 mg/ml bovine serum albumin upon a heated stage (37 degrees C) and were observed constantly through an inverted microscope. The endpoint of the bioassay was the limits of the zona no longer being seen clearly at x 200 magnification, and the time taken for each zona to dissolve was recorded. A dose-dependent response in dissolution time was clearly seen, with 1% alpha-chymotrypsin being chosen as the routine working solution. Cryopreservation of 2-cell mouse embryos using propanediol did not cause zona hardening but induced a small and significant softening, as gauged by the time taken for zona dissolution (2181 +/- 167 versus 1864 +/- 82 s). Zona hardening was not suspected to occur after the freezing of human embryos as there was no difference in implantation rates per embryo for in-vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI) treatment cycles between fresh [IVF: 63/644 (9.7%); ICSI: 51/330 (15.5%)] and frozen embryos [IVF: 36/458 (7.9%); ICSI: 18/112 (16.1%)]. Conversely, significant hardening of the zonae of mature oocytes was seen following cryopreservation (747 +/- 393 s) compared with freshly ovulated oocytes (151 +/- 68 s). It is concluded that (i) the freezing of murine oocytes with propanediol results in zona hardening, implying a possible benefit of ICSI after the cryopreservation of human oocytes, and (ii) the cryopreservation of embryos is not associated with zona hardening or reduced implantation, making microdissection of the zona in such cases generally unwarranted.

Animals↗
PubMed1998

Amnio-allantoic fluid exchange for prevention of intestinal damage in gastroschisis II: Effects of exchange performed by using two different solutions.

The prevention of intestinal damage in gastroschisis was reported after amnio-allantoic fluid (AAF) exchange using serum saline. However it is not clear why AAF exchange prevents intestinal damage. Are some harmful chemicals withdrawn from AAF by exchange or sodium content of AAF is merely increased? A study was planned to find the end results of AAF exchange performed by using two different solutions in the chicken embryo gastroschisis model. After creation of gastroschisis, three groups were studied. In the first group AAF exchange was not performed. In the second group AAF exchange was performed using 0.075% NaCl solution (physiologic saline for chicken). In the third group AAF exchange was performed using 0.054% NaCl plus 1% dextrose solution. Exchange with two different solutions prevented cellular infiltration and fibrous peel formation in intestines which are observed in the non-treatment group. In the third group, intestinal edema was an additional pathologic finding. This study shows that in gastroschisis, the intestines outside the abdominal cavity are very sensitive to the quality of the fluid in which they are bathed. The intestinal damage resembling that encountered in human gastroschisis can be prevented by removing the harmful chemicals from AAF by exchange.

Allantois↗
PubMed1997

Serum concentrations of oestradiol-17beta, progesterone, relaxin and chorionic gonadotrophin during blastocyst implantation in natural pregnancy cycle and in embryo transfer cycle in the rhesus monkey.

The present study was undertaken to assess the temporal association between the profiles of serum concentrations of oestradiol-17beta, progesterone, chorionic gonadotrophin (CG) and relaxin in pregnancies established naturally, and after embryo transfer, as well as in failed pregnancies in rhesus monkeys. In naturally mated cycles (group 1) a conception rate of 75% was obtained. In group 1, the mean day of CG detection in serum was 11.5 +/- 1.9 day post-ovulation, and for relaxin, 9.0 +/- 2.5 day post-ovulation. In group 2, embryo transfer to synchronous, non-mated surrogate recipients was performed; seven embryo transfer cycles yielded three pregnancies which were allowed to continue to term and normal infants were delivered. In embryo transfer cycles the mean day of CG detection was 14.8 +/- 1.8 day post-ovulation, and for relaxin, 11.4 +/- 2.6 day post-ovulation. A delay of about 3 days was observed in the appearance in circulation of CG (P < 0.05) and also of relaxin (P < 0.05) between natural mated and embryo transfer conception cycles. Significant differences (P < 0.05 for progesterone and P < 0.03 for oestradiol) were obtained for the areas under the curves for progesterone and oestradiol between days 12 and 16 in conception cycles compared with failed pregnancies. These data provide the first observation of the normal hormonal signals associated with maternal recognition of transferred embryos during the peri-implantation period, and suggest that the use of such an experimental primate embryo transfer model may help to elucidate components of maternal and embryonic signal-response mechanisms during embryo implantation.

Abortion, Veterinary↗
PubMed2006

Antisense inhibition of cyclin D1 expression is equivalent to flavopiridol for radiosensitization of zebrafish embryos.

PURPOSE: Flavopiridol, a small molecule pan-cyclin inhibitor, has been shown to enhance the radiation response of tumor cells both in vitro and in vivo. The clinical utility of flavopiridol, however, is limited by toxicity, previously attributed to pleiotropic inhibitory effects on several targets affecting multiple signal transduction pathways. Here we used zebrafish embryos to investigate radiosensitizing effects of flavopiridol in normal tissues. METHODS AND MATERIALS: Zebrafish embryos at the 1- to 4-cell stage were treated with 500 nM flavopiridol or injected with 0.5 pmol antisense hydroxylprolyl-phosphono nucleic acid oligomers to reduce cyclin D1 expression, then subjected to ionizing radiation (IR) or no radiation. RESULTS: Flavopiridol-treated embryos demonstrated a twofold increase in mortality after exposure to 40 Gy by 96 hpf and developed distinct radiation-induced defects in midline development (designated as the "curly up" phenotype) at higher rates when compared with embryos receiving IR only. Cyclin D1-deficient embryos had virtually identical IR sensitivity profiles when compared with embryos treated with flavopiridol. This was particularly evident for the IR-induced curly up phenotype, which was greatly exacerbated by both flavopriridol and cyclin D1 downregulation. CONCLUSIONS: Treatment of zebrafish embryos with flavopiridol enhanced radiation sensitivity of zebrafish embryos to a degree that was very similar to that associated with downregulation of cyclin D1 expression. These results are consistent with the hypothesis that inhibition of cyclin D1 is sufficient to account for the radiosensitizing action of flavopiridol in the zebrafish embryo vertebrate model.

Animals↗
PubMed1999

A three-dimensional model of the mouse at embryonic day 9.

This paper describes a digital, three-dimensional model of the mouse embryo at E9. The model was made by reconstruction from images of serial histological sections digitally warped to remove distortions and has a resolution of approximately 9 microns. The model can be digitally resectioned in any plane to provide images which resemble conventional histological sections. The main tissues have been identified and delineated by digital painting so that the anatomical components can be visualized and manipulated in 3-D surface- and volume-rendered views. This provides a three-dimensional definition of anatomy that will provide a useful tool for interpreting and understanding spatial data in mouse embryos. The anatomy of the model is discussed where it provides landmarks for interpretation and navigation or where it is unexpected in light of existing descriptions of the E9 mouse embryo. The complete anatomy is not presented in this paper but will be available on CD-ROM. A detailed description of the technical aspects of the construction of the model is included in an appendix. The model is the first of a series that will form the basis for an atlas/database of mouse development. This reconstruction and its associated anatomy are available in a variety of data formats with some supporting software from http:@genex.hgu.mrc.ac.uk/.

Anatomy, Cross-Sectional↗
PubMed2003

Ex ova chick chorioallantoic membrane as a novel model for evaluation of tissue responses to biomaterials and implants.

One of the major obstacles in developing rationale strategies to control inflammation and fibrosis surrounding implants is the lack of a simple and inexpensive in vivo model to screen tissue reactions to various biomaterials and implants. To begin to fill this gap, we have developed an ex ova model of the chick embryo chorioallantoic membrane (CAM) for testing of tissue reaction to biomaterials and implants. For these studies, we evaluated tissue reactions (inflammation and fibrosis) to two commonly used biomaterials (nylon and silastic) grossly and histologically in the ex ova CAM. Nylon mesh was incorporated within the CAM tissue 4 days postplacement. After 8 days postplacement, the nylon mesh was totally incorporated into the CAM. Histologically, little or no inflammation was seen associated with the incorporated nylon mesh at any time point. In the case of silastic tubing, significant incorporation of the CAM was seen grossly by 1-2 days postplacement. Incorporation of the tubing continued at day 8 postplacement of the silastic tubing, with ingrowth of the CAM into the lumen of the tubing. Histological evaluation of CAMs indicated that no significant tissue reactions (inflammation or fibrosis) occurred in the CAM tissue surrounding the silastic tubing or in the CAM tissue and vasculature that had grown into the silastic tubing. To our knowledge, this report represents the first investigation of the usage of the ex ova CAM model, a shell-less chick embryo model (ex ova), as an in vivo model to test the tissue reactions to biomaterials and implants.

Allantois↗
PubMed2006

Modeling segmental patterning in Drosophila: Maternal and gap genes.

We propose a new mathematical model describing the establishment of maternal and gap proteins segmental patterning along the antero-posterior axis of the Drosophila early embryo. This model is based on experimental data and, without recurring to pre-defined activation thresholds, predicts qualitatively and quantitatively the expression patterns of the maternal and gap proteins, as well as the expression patterns of proteins resulting from mRNA ectopic expression and from some loss-of-function mutations. We conclude that the gap genes segmental patterning and consequent spatial organization of the embryo is determined by three main factors: (1) the initial positioning of the maternal bicoid and torso mRNA inside the egg, and subsequent diffusion of the corresponding proteins; (2) the structure of the genetic regulatory network; (3) the role of conservation laws in the establishment of steady and non-uniform spatial distributions of non-diffusing proteins.

Animals↗
PubMed1992

Preclinical models for human pre-embryo biopsy and genetic diagnosis. II. Polymerase chain reaction amplification of deoxyribonucleic acid from single lymphoblasts and blastomeres with mutation detection.

OBJECTIVE: To demonstrate the use of the polymerase chain reaction in the amplification of deoxyribonucleic acid (DNA) from single human lymphoblasts and mouse blastomeres. Amplified target genes for diagnosis of sickle cell anemia and Tay-Sachs are shown. Similarly, the sparce fur mouse model for ornithine transcarbamylase deficiency was used as an X-linked system for demonstration of mutation detection after biopsy of a single blastomere. A new diagnostic method for the detection of the ornithine transcarbamylase mutation using the restriction enzyme Mse I is presented. Accuracy and reproducibility were assured. DESIGN: Polymerase chain reaction proficiency test for amplification from single cells was studied. Also, accuracy of mutation detection systems was demonstrated. SETTING: Laboratories of The Jones Institute for Reproductive Medicine, Department of Obstetrics and Gynecology, Eastern Virginia Medical School. PATIENTS, PARTICIPANTS: We used the sparse fur mouse model and human blood cells. INTERVENTIONS: Pre-embryo biopsy, polymerase chain reaction amplification, and mutation detection were performed. MAIN OUTCOME MEASURES: Accuracy and reproducibility of DNA amplification without contamination, as well as efficient diagnostic analysis, from both single somatic and embryonic cells were shown. RESULTS: DNA amplification from single cells was uniformly rapid (6 to 10 hours) reproducible (n = 220) and accurate (n = 52). CONCLUSIONS: Our findings support the feasibility of clinical application for pre-embryo biopsy and genetic diagnosis of specific heritable diseases.

Amino Acid Sequence↗