The Experts below are selected from a list of 249 Experts worldwide ranked by ideXlab platform
Arkady Torchinsky - One of the best experts on this subject based on the ideXlab platform.
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Bone loss in adult offspring induced by low-dose exposure to Teratogens
Journal of Bone and Mineral Metabolism, 2012Co-Authors: Arkady Torchinsky, Limor Mizrahi, Shoshana Savion, Vladimir Toder, Ron Shahar, Eugene KobylianskyAbstract:Maternal malnutrition during pregnancy was shown by numerous studies to result in the birth of offspring exhibiting altered bone characteristics, which are indicative of bone loss. We hypothesized that not only maternal malnutrition but also some developmental toxicants (Teratogens) given at a dose inducing neither structural anomalies nor growth retardation can detrimentally affect skeletal health in adult offspring. To check this hypothesis, pregnant mice were exposed to a single injection of 5-aza-2-deoxycytidine (5-AZA) (a teratogen capable of inducing phocomelia of the hind limbs) at a sub-threshold teratogenic dose. Micro-computed tomography scanning revealed that femora of 5-month-old male offspring exposed in uterus to 5-AZA had trabecular microarchitecture indicative of bone loss. Furthermore, exposure to 5-AZA increased the susceptibility of offspring to postnatal chronic mild stress, which has been shown to induce bone loss in mice. While exploring possible mechanisms underlying this phenomenon, we observed that the expression of some microRNAs, which have been demonstrated as regulators of key osteoblastogenic genes, was altered in hind limb buds of embryos exposed to 5-AZA. Furthermore, the expression of receptor activator of nuclear factor kappa B ligand (RANKL) in femoral stromal/osteoblastic cells of 5-month-old offspring of 5-AZA-treated females was found to be increased. Collectively, this study implies for the first time that single low-dose exposure to a teratogen can induce bone loss in adult offspring, possibly via alteration of embryonic microRNAs and RANKL expression.
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p53 regulates cyclophosphamide teratogenesis by controlling caspases 3 8 9 activation and nf κb dna binding
Reproduction, 2007Co-Authors: Olga Pekar, Shoshana Savion, Amos Fein, V Toder, Nataly Molotski, Arkady TorchinskyAbstract:The tumor suppressor protein p53 regulates the sensitivity of embryos to such human Teratogens as ionizing radiation, diabetes, and cytostatics. Yet, the molecular mechanisms whereby it fulfills this function remain undefined. We used p53 heterozygous (p53 C/K ) female mice mated with p53 C/K males and then exposed to cyclophosphamide (CP) to test whethercaspases 3, 8, and 9 and the transcription factor nuclear factor (NF)-kB may serve as p53 targets. Mice were exposed to CPon day 12 of pregnancyand killed on days 15 and 18 of pregnancy to evaluate CP-induced teratogenic effect. The brain and limbs of embryos harvested 24 h after CP treatment were used to evaluate NF-kB (p65) DNA-binding activity by an ELISA-based method, the activity of the caspases by appropriate colorimetric kits, apoptosis, and cell proliferation by TUNEL, and 5 0 -bromo-2 0 -deoxyuridine incorporation respectively. We observed that the activation of caspases 3, 8, and 9 and the suppression of NF-kB DNA binding following CP-induced teratogenic insult took place only in teratologically sensitive organs of p53 C/C but not p53 K/K embryos. CP-induced apoptosis and suppression of cell proliferation were also more intensive in the former, and they exhibited a higher incidence of structural anomalies, such as open eyes, digit, limb, and tail anomalies. The analysis of the correlations between the p53 embryonic genotype, the activity of the tested molecules, and the CP-induced dysmorphic events at the cellular and organ level suggests caspases 3, 8, and 9 and NF-kB as components of p53-targeting mechanisms in embryos exposed to the teratogen.
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teratogen induced apoptotic cell death does the apoptotic machinery act as a protector of embryos exposed to Teratogens
Birth Defects Research Part C-embryo Today-reviews, 2005Co-Authors: Arkady Torchinsky, Amos Fein, V ToderAbstract:Considerable evidence has been collected demonstrating that many Teratogens induce apoptotic cell death in embryonic structures that turn out to be malformed in fetuses and newborns. Apoptosis is a genetically regulated process that is realized by the activation of death and prosurvival signaling cascades, and the interplay between these cascades determines whether the cell exposed to apoptotic stimuli dies or survives. Therefore, there is intense interest in understanding how the apoptotic machinery functions in embryos exposed to Teratogens. However, the interpretation of the results obtained remains problematic. The main problem is that excessive embryonic cell death, regardless of its nature, if uncompensated for, ultimately leads to maldevelopment or embryonic death. Therefore, we can easily interpret results when the intensity of teratogen-induced cell death and the severity or incidence of teratogeninduced anomalies directly correlate with each other. However, when teratogen-induced cell death is not followed by the formation of anomalies, a usual explanation is that teratogen-induced apoptotic cell death contributes to the renewal of teratogen-targeted cell populations by promoting the removal of injured cells. It is clear that such an explanation leaves vague the role of the antiapoptotic signaling mechanism (and, hence, the apoptotic machinery as a whole) with respect to protecting the embryo against teratogenic stress. In this review, we summarize the data from studies addressing the function of the apoptotic machinery in embryos exposed to Teratogens, and then we discuss approaches to interpreting the results of these studies. We hypothesize that activation of a proapoptotic signaling in teratogen-targeted cell populations is a necessary condition for an antiapoptotic signaling that counteracts the process of maldevelopment to be activated. If such a scenario is true, we need to modify our approaches to choosing molecular targets for studies addressing this topic. Birth Defects Research (Part C) 75: 353–361, 2005. © 2006 Wiley-Liss, Inc.
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Teratogen‐induced apoptotic cell death: Does the apoptotic machinery act as a protector of embryos exposed to Teratogens?
Birth Defects Research Part C-embryo Today-reviews, 2005Co-Authors: Arkady Torchinsky, Amos Fein, Vladimir ToderAbstract:Considerable evidence has been collected demonstrating that many Teratogens induce apoptotic cell death in embryonic structures that turn out to be malformed in fetuses and newborns. Apoptosis is a genetically regulated process that is realized by the activation of death and prosurvival signaling cascades, and the interplay between these cascades determines whether the cell exposed to apoptotic stimuli dies or survives. Therefore, there is intense interest in understanding how the apoptotic machinery functions in embryos exposed to Teratogens. However, the interpretation of the results obtained remains problematic. The main problem is that excessive embryonic cell death, regardless of its nature, if uncompensated for, ultimately leads to maldevelopment or embryonic death. Therefore, we can easily interpret results when the intensity of teratogen-induced cell death and the severity or incidence of teratogeninduced anomalies directly correlate with each other. However, when teratogen-induced cell death is not followed by the formation of anomalies, a usual explanation is that teratogen-induced apoptotic cell death contributes to the renewal of teratogen-targeted cell populations by promoting the removal of injured cells. It is clear that such an explanation leaves vague the role of the antiapoptotic signaling mechanism (and, hence, the apoptotic machinery as a whole) with respect to protecting the embryo against teratogenic stress. In this review, we summarize the data from studies addressing the function of the apoptotic machinery in embryos exposed to Teratogens, and then we discuss approaches to interpreting the results of these studies. We hypothesize that activation of a proapoptotic signaling in teratogen-targeted cell populations is a necessary condition for an antiapoptotic signaling that counteracts the process of maldevelopment to be activated. If such a scenario is true, we need to modify our approaches to choosing molecular targets for studies addressing this topic. Birth Defects Research (Part C) 75: 353–361, 2005. © 2006 Wiley-Liss, Inc.
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NF-κB DNA-binding activity in embryos responding to a teratogen, cyclophosphamide
BMC Developmental Biology, 2002Co-Authors: Arkady Torchinsky, Shoshana Savion, Lucy Lishanski, Orit Wolstein, Jeanne Shepshelovich, Hasida Orenstein, Zeev Zaslavsky, Howard Carp, Alexander Brill, Rivka DiksteinAbstract:Background The Rel/NF-κB transcription factors have been shown to regulate apoptosis in different cell types, acting as inducers or blockers in a stimuli- and cell type-dependent fashion. One of the Rel/NF-κB subunits, RelA, has been shown to be crucial for normal embryonic development, in which it functions in the embryonic liver as a protector against TNFα-induced physiological apoptosis. This study assesses whether NF-κB may be involved in the embryo's response to Teratogens. Fot this, we evaluated how NF-KappaB DNA binding activity in embryonic organs demonstraiting differential sensitivity to a reference teratogen, cyclophosphamide, correlates with dysmorphic events induced by the teratogen at the cellular level (excessive apoptosis) and at the organ level (structural anomalies).
Philip E. Mirkes - One of the best experts on this subject based on the ideXlab platform.
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Teratogen-induced activation of p53 in early postimplantation mouse embryos.
Toxicological Sciences, 2006Co-Authors: Hiromi Hosako, Sally A. Little, Marianne Barrier, Philip E. MirkesAbstract:Hyperthermia (HS) and 4-hydroperoxycyclophosphamide (4CP) activate the mitochondrial apoptotic pathway in day 9 mouse embryos. Previous microarray analyses Microarray analyses revealed that several p53 target genes are upregulated after exposure to HS or 4CP, suggesting a role for p53 in teratogen-induced apoptosis. To explore the role of p53, we assessed the activation of p53 in day 9 mouse embryos exposed to HS or 4CP in vitro. Both Teratogens induced the accumulation of p53 and phosphorylation of p53 at ser-15, two hallmarks of p53 activation. HS and 4CP also induced an increase in Noxa and Puma mRNAs, transcripts of two known proapoptotic p53 target genes; however, these two Teratogens did not induce significant increases in NOXA and PUMA proteins, suggesting that p53 does not activate the mitochondrial apoptotic pathway by transcriptionally upregulating the expression of NOXA and PUMA proteins. HS and 4CP also induced the expression of p21 mRNA and protein, suggesting a role for p53 in teratogen-induced cell cycle arrest. Previously, we also showed that HS and 4CP activate the apoptotic pathway in the embryo proper (head and trunk) but not in the heart. We now show that HS and 4CP induce a robust activation of p53 in the embryo proper but an attenuated induction in the heart. HS and 4CP induce the expression of p21 protein in majority of the cells in the embryo; however, expression of NOXA and PUMA proteins were not significantly induced in heads, hearts, or trunks of day 9 embryos. Overall, our results suggest that p53 may play a transcription-dependent role in teratogen-induced cell cycle arrest but a transcription-independent role in teratogen-induced apoptosis in day 9 mouse embryos exposed to HS or 4CP.
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Teratogen-induced activation of caspase-6 and caspase-7 in early postimplantation mouse embryos
Cell Biology and Toxicology, 2003Co-Authors: S.a. Little, Philip E. MirkesAbstract:Background : Previous work has shown that Teratogens such as hyperthermia (HS), 4-hydroperoxycyclophosphamide (4CP), and staurosporine (ST) induce cell death in day 9 mouse embryos by activating the mitochondrial apoptotic pathway. Key to the activation of this pathway is the activation of a caspase cascade involving the cleavage-induced activation of an initiator procaspase, caspase-9, and the downstream effector procaspase, caspase-3. For example, procaspase-3, an inactive proenzyme of 32 kDa is cleaved by activated caspase-9 to generate a large subunit of approximately 17 kDa and a small subunit of approximately 10 kDa. In turn, caspase-3 is known to target a variety of cellular proteins for proteolytic cleavage as part of the process by which dying cells are eliminated. Previous work has also shown that neuroepithelial cells are sensitive to teratogen-induced activation of this pathway and subsequent cell death whereas cells of the heart are resistant. Although caspase-3 is a key effector caspase activated by Teratogens, two other effector caspases, caspase-6 and caspase-7, are known; however, their role in teratogen-induced cell death is unknown. Methods : Because cleavage-induced generation of specific subunits is the most specific assay for activation of caspases, we have used antibodies that recognize the procaspase and one of its active subunits and a Western blot approach to assess the activation of caspase-6 and caspase-7 in day 9 mouse embryos (or heads, hearts and trunks isolated from whole embryos) exposed to HS, 4CP, and ST. To probe the relationship between teratogen-induced activation of caspase-9/caspase-3 and the activation of caspase-6/caspase-7, we used a mitochondrial-free embryo lysate with or without the addition of cytochrome c, recombinant active caspase-3, or recombinant active caspase-9. Results : Western blot analyses show that these three Teratogens, HS, 4CP, and ST, induce the activation of procaspase-6 (appearance of the 13 kDa subunit, p13) and caspase-7 (appearance of the 19 kDa subunit, p19) in day 9 mouse embryos. In vitro studies showed that both caspase-6 and caspase-7 could be activated by the addition of cytochrome c to a lysate prepared from untreated embryos. In addition, caspase-6 could be activated by the addition of either recombinant caspase-3 or caspase-9 to a lysate prepared from untreated embryos. In contrast, caspase-7 could be activated by addition of recombinant caspase-3 but only minimally by recombinant caspase-9. Like caspase-9/caspase-3, caspase-6 and caspase-7 were not activated in hearts isolated from embryos exposed to these three Teratogens. Conclusions : HS, 4CP and ST induce the cleavage-dependent activation of caspase-6 and caspase-7 in day 9 mouse embryos. Results using DEVD-CHO, a caspase-3 inhibitor, suggest that teratogen-induced activation of caspase-6 is mediated by caspase-3. In addition, our data suggest that caspase-7 is activated primarily by caspase-3; however, we cannot rule out the possibility that this caspase is also activated by caspase-9. Finally, we also show that teratogen-induced activation of caspase-6 and caspase-7 are blocked in the heart, a tissue resistant to teratogen-induced cell death.
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Teratogen-induced activation of the mitochondrial apoptotic pathway in the yolk sac of day 9 mouse embryos.
Birth Defects Research Part A-clinical and Molecular Teratology, 2003Co-Authors: Donna Soleman, Sally A. Little, Leanne Cornel, Philip E. MirkesAbstract:BACKGROUND: Using vital dyes, we have previously shown that while hyperthermia (HS), 4-hydroperoxycyclophosphamide (4CP), and staurosporine (ST) induce cell death within specific tissues (e.g., neuroepithelium) of day 9 mouse embryos, cells of the heart are resistant to the cell death-inducing potential of these Teratogens. Subsequent work has shown that teratogen-induced cell death is associated with activation of the mitochondrial apoptotic pathway, i.e., release of cytochrome c from mitochondria, activation/cleavage of procaspase-9, -3, and -2, inactivation of poly(ADP-ribose) polymerase, and internucleosomal fragmentation of DNA, whereas resistance to teratogen-induced cell death in the heart is associated with a failure to activate this pathway. Teratogen-induced activation of the mitochondrial apoptotic pathway is initiated between 2.5 and 5 hr after Teratogens are added to the culture medium. Because both the heart and the surrounding yolk sac are essential to successful development of mouse embryos during early postimplantation mouse development, we hypothesized that cells of the yolk sac are also resistant to teratogen-induced cell death. METHODS: To test our hypothesis, we cultured day 8.5 mouse conceptuses (embryo plus yolk sac) in whole embryo culture. On the morning of day 9, conceptuses were exposed to HS (43 degrees C for 15 min and then returned to 37 degrees C), 4CP (40 microM, 5-10 hr), or ST (0.5 microM 5-10 hr). At 5 and 10 hr after addition of teratogen, conceptuses were removed from culture and dissected into embryo and yolk sac. Activation of the mitochondrial apoptotic pathway was then assessed separately in embryos and yolk sacs using Western blot analysis to detect activation of procaspase-9, -3, and -2, enzyme assays to measure caspase-3-like activity, and immunohistochemistry to detect caspase-3 activation/cleavage in yolk sac cells. RESULTS: Although Western blot analysis revealed that procaspase-9, -3, and -2 were activated/cleaved in the embryo as early as the 5-hr time point, activation/cleavage of these caspases could not be detected in the yolk sac at either the 5- or 10-hr time point. Using an enzyme assay, we determined that caspase-3-like activity in the yolk sac was induced 1.7-fold by HS, 4.4-fold by 4CP, and 3.3-fold by ST. This compares to the embryo in which caspase-3-like activity was induced 45-fold by HS, 26-fold by 4CP, and 45-fold by ST. Using an antibody specific for the active p17 subunit of caspase-3 and immunohistochemistry, we were able to detect a small number of yolk sac cells showing caspase-3 activation. Thus, the low-level induction of caspase-3-like activity in the yolk sac is in part related to activation/cleavage of procaspase-3. CONCLUSIONS: Results presented indicate that cells of the extraembryonic yolk sac, like cells of the embryonic heart, are substantially more resistant to teratogen-induced activation of the mitochondrial apoptotic pathway and subsequent apoptosis compared to other embryonic tissues, particularly cells of the neuroepithelium.
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Teratogen-induced cell death in postimplantation mouse embryos: differential tissue sensitivity and hallmarks of apoptosis.
Cell Death & Differentiation, 1998Co-Authors: Philip E. Mirkes, Sally A. LittleAbstract:Teratogen-induced cell death is a common event in the pathogenesis associated with tissues destined to be malformed. Although the importance of this cell death is recognized, little information is available concerning the biochemistry of teratogen-induced cell death. We show that three Teratogens, hyperthermia, cyclophosphamide and sodium arsenite induce an increase in cell death in day 9.0 mouse embryos with concurrent induction of DNA fragmentation, activation of caspase-3 and the cleavage of poly (ADP-ribose) polymerase (PARP). Teratogen-induced cell death is also selective, i.e., some cells within a tissue die while others survive. In addition, cells within some tissues die when exposed to Teratogens while cells in other tissues are relatively resistant to teratogen-induced cell death. An example of the latter selectivity is seen in the cells of the developing heart, which are resistant to the cytotoxic potential of many Teratogens. We show that the absence of cell death in the heart is accompanied by the complete lack of DNA fragmentation, activtion of caspase-3 and the cleavage of PARP.
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induction of a heat shock response hsp 72 in rat embryos exposed to selected chemical Teratogens
Teratology, 1994Co-Authors: Philip E. Mirkes, Barbara Doggett, Leanne CornelAbstract:A monoclonal antibody to the 72 kD heat shock protein (HSP 72), Western blot analysis and 2-D gel electrophoresis/autoradiography were used to determine whether selected chemical Teratogens induced the synthesis and accumulation of HSP 72 in postimplantation rat embryos exposed in vitro. The chemical Teratogens studied include N-Acetoxy-2-acetylaminofluorene (N-Ac-AAF), cadmium chloride (CAD), cyclophosphamide (CP), sodium arsenite (AS), and sodium salicylate (SAL). Exposures to test chemicals were selected that produced obvious embryotoxicity characterized by abnormal development and growth retardation. Of the five chemical Teratogens studied, AS and SAL induced the synthesis and accumulation of HSP 72 in day 10 rat embryos. The kinetics of HSP 72 accumulation, however, differed between AS- and SAL-treated embryos. Maximal levels of HSP 72 were observed 24 hours after AS exposure and 10 hours after SAL exposure. N-Ac-AAF, CD, and CP induced obvious embryotoxicity; however, none of these chemical Teratogens induced HSP 72 at any of the timepoints assayed. Although only a small sample of chemical Teratogens was studied, our results suggest that the heat shock response, characterized by the synthesis and accumulation of HSP 72, is not a general biomarker for chemical Teratogens. © 1994 Wiley-Liss, Inc.
V Toder - One of the best experts on this subject based on the ideXlab platform.
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p53 regulates cyclophosphamide teratogenesis by controlling caspases 3 8 9 activation and nf κb dna binding
Reproduction, 2007Co-Authors: Olga Pekar, Shoshana Savion, Amos Fein, V Toder, Nataly Molotski, Arkady TorchinskyAbstract:The tumor suppressor protein p53 regulates the sensitivity of embryos to such human Teratogens as ionizing radiation, diabetes, and cytostatics. Yet, the molecular mechanisms whereby it fulfills this function remain undefined. We used p53 heterozygous (p53 C/K ) female mice mated with p53 C/K males and then exposed to cyclophosphamide (CP) to test whethercaspases 3, 8, and 9 and the transcription factor nuclear factor (NF)-kB may serve as p53 targets. Mice were exposed to CPon day 12 of pregnancyand killed on days 15 and 18 of pregnancy to evaluate CP-induced teratogenic effect. The brain and limbs of embryos harvested 24 h after CP treatment were used to evaluate NF-kB (p65) DNA-binding activity by an ELISA-based method, the activity of the caspases by appropriate colorimetric kits, apoptosis, and cell proliferation by TUNEL, and 5 0 -bromo-2 0 -deoxyuridine incorporation respectively. We observed that the activation of caspases 3, 8, and 9 and the suppression of NF-kB DNA binding following CP-induced teratogenic insult took place only in teratologically sensitive organs of p53 C/C but not p53 K/K embryos. CP-induced apoptosis and suppression of cell proliferation were also more intensive in the former, and they exhibited a higher incidence of structural anomalies, such as open eyes, digit, limb, and tail anomalies. The analysis of the correlations between the p53 embryonic genotype, the activity of the tested molecules, and the CP-induced dysmorphic events at the cellular and organ level suggests caspases 3, 8, and 9 and NF-kB as components of p53-targeting mechanisms in embryos exposed to the teratogen.
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teratogen induced apoptotic cell death does the apoptotic machinery act as a protector of embryos exposed to Teratogens
Birth Defects Research Part C-embryo Today-reviews, 2005Co-Authors: Arkady Torchinsky, Amos Fein, V ToderAbstract:Considerable evidence has been collected demonstrating that many Teratogens induce apoptotic cell death in embryonic structures that turn out to be malformed in fetuses and newborns. Apoptosis is a genetically regulated process that is realized by the activation of death and prosurvival signaling cascades, and the interplay between these cascades determines whether the cell exposed to apoptotic stimuli dies or survives. Therefore, there is intense interest in understanding how the apoptotic machinery functions in embryos exposed to Teratogens. However, the interpretation of the results obtained remains problematic. The main problem is that excessive embryonic cell death, regardless of its nature, if uncompensated for, ultimately leads to maldevelopment or embryonic death. Therefore, we can easily interpret results when the intensity of teratogen-induced cell death and the severity or incidence of teratogeninduced anomalies directly correlate with each other. However, when teratogen-induced cell death is not followed by the formation of anomalies, a usual explanation is that teratogen-induced apoptotic cell death contributes to the renewal of teratogen-targeted cell populations by promoting the removal of injured cells. It is clear that such an explanation leaves vague the role of the antiapoptotic signaling mechanism (and, hence, the apoptotic machinery as a whole) with respect to protecting the embryo against teratogenic stress. In this review, we summarize the data from studies addressing the function of the apoptotic machinery in embryos exposed to Teratogens, and then we discuss approaches to interpreting the results of these studies. We hypothesize that activation of a proapoptotic signaling in teratogen-targeted cell populations is a necessary condition for an antiapoptotic signaling that counteracts the process of maldevelopment to be activated. If such a scenario is true, we need to modify our approaches to choosing molecular targets for studies addressing this topic. Birth Defects Research (Part C) 75: 353–361, 2005. © 2006 Wiley-Liss, Inc.
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immunoteratology i mhc involvement in the embryo response to Teratogens in mice
American Journal of Reproductive Immunology, 1995Co-Authors: Arkady Torchinsky, Amos Fein, V ToderAbstract:PROBLEM: The present study was carried out to evaluate an involvement of MHC-associated maternal immunoreactivity in response to environmental Teratogens. METHODS: Two chemicals, cyclophosphamide (CP) and 2,3-quinoxalinedimetanol, 1,4-dioxide (QD) were used as the reference Teratogens (RT). The response to these RT was investigated in syngeneically and allogeneically mated CBA/J and C57B1/6 mice. In part of C57B1/6 female mice, paraaortic lymph nodes were extirpated 14 days before mating to allogeneic or syngeneic males. Twenty or 40 mg/kg of CP or 300 or 600 mg/kg of QD were injected on day 12 and 9 of pregnancy, accordingly (vaginal plug indicates day 1 of pregnancy). On day 19 of pregnancy implantation sites, resorptions, live and dead fetuses were recorded and live fetuses were examined with methods routinely used in applied teratology. RESULTS: Both mice strains showed equal response to Teratogens but the RT-induced effect was significantly weaker in allogeneic than syngeneic mouse combinations. Extirpation of draining lymph nodes dramatically increased the sensitivity to RT in allogeneically mated females but failed to alter that of syngeneically mated ones. CONCLUSION: The results of this study suggest that fetomaternal MHC incompatibility exerts the favourable influence on teratological resistance of the embryo and MHC-associated immunoreactivity of “mother-fetus” axis is possibly responsible for this effect.
Amos Fein - One of the best experts on this subject based on the ideXlab platform.
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p53 regulates cyclophosphamide teratogenesis by controlling caspases 3 8 9 activation and nf κb dna binding
Reproduction, 2007Co-Authors: Olga Pekar, Shoshana Savion, Amos Fein, V Toder, Nataly Molotski, Arkady TorchinskyAbstract:The tumor suppressor protein p53 regulates the sensitivity of embryos to such human Teratogens as ionizing radiation, diabetes, and cytostatics. Yet, the molecular mechanisms whereby it fulfills this function remain undefined. We used p53 heterozygous (p53 C/K ) female mice mated with p53 C/K males and then exposed to cyclophosphamide (CP) to test whethercaspases 3, 8, and 9 and the transcription factor nuclear factor (NF)-kB may serve as p53 targets. Mice were exposed to CPon day 12 of pregnancyand killed on days 15 and 18 of pregnancy to evaluate CP-induced teratogenic effect. The brain and limbs of embryos harvested 24 h after CP treatment were used to evaluate NF-kB (p65) DNA-binding activity by an ELISA-based method, the activity of the caspases by appropriate colorimetric kits, apoptosis, and cell proliferation by TUNEL, and 5 0 -bromo-2 0 -deoxyuridine incorporation respectively. We observed that the activation of caspases 3, 8, and 9 and the suppression of NF-kB DNA binding following CP-induced teratogenic insult took place only in teratologically sensitive organs of p53 C/C but not p53 K/K embryos. CP-induced apoptosis and suppression of cell proliferation were also more intensive in the former, and they exhibited a higher incidence of structural anomalies, such as open eyes, digit, limb, and tail anomalies. The analysis of the correlations between the p53 embryonic genotype, the activity of the tested molecules, and the CP-induced dysmorphic events at the cellular and organ level suggests caspases 3, 8, and 9 and NF-kB as components of p53-targeting mechanisms in embryos exposed to the teratogen.
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teratogen induced apoptotic cell death does the apoptotic machinery act as a protector of embryos exposed to Teratogens
Birth Defects Research Part C-embryo Today-reviews, 2005Co-Authors: Arkady Torchinsky, Amos Fein, V ToderAbstract:Considerable evidence has been collected demonstrating that many Teratogens induce apoptotic cell death in embryonic structures that turn out to be malformed in fetuses and newborns. Apoptosis is a genetically regulated process that is realized by the activation of death and prosurvival signaling cascades, and the interplay between these cascades determines whether the cell exposed to apoptotic stimuli dies or survives. Therefore, there is intense interest in understanding how the apoptotic machinery functions in embryos exposed to Teratogens. However, the interpretation of the results obtained remains problematic. The main problem is that excessive embryonic cell death, regardless of its nature, if uncompensated for, ultimately leads to maldevelopment or embryonic death. Therefore, we can easily interpret results when the intensity of teratogen-induced cell death and the severity or incidence of teratogeninduced anomalies directly correlate with each other. However, when teratogen-induced cell death is not followed by the formation of anomalies, a usual explanation is that teratogen-induced apoptotic cell death contributes to the renewal of teratogen-targeted cell populations by promoting the removal of injured cells. It is clear that such an explanation leaves vague the role of the antiapoptotic signaling mechanism (and, hence, the apoptotic machinery as a whole) with respect to protecting the embryo against teratogenic stress. In this review, we summarize the data from studies addressing the function of the apoptotic machinery in embryos exposed to Teratogens, and then we discuss approaches to interpreting the results of these studies. We hypothesize that activation of a proapoptotic signaling in teratogen-targeted cell populations is a necessary condition for an antiapoptotic signaling that counteracts the process of maldevelopment to be activated. If such a scenario is true, we need to modify our approaches to choosing molecular targets for studies addressing this topic. Birth Defects Research (Part C) 75: 353–361, 2005. © 2006 Wiley-Liss, Inc.
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Teratogen‐induced apoptotic cell death: Does the apoptotic machinery act as a protector of embryos exposed to Teratogens?
Birth Defects Research Part C-embryo Today-reviews, 2005Co-Authors: Arkady Torchinsky, Amos Fein, Vladimir ToderAbstract:Considerable evidence has been collected demonstrating that many Teratogens induce apoptotic cell death in embryonic structures that turn out to be malformed in fetuses and newborns. Apoptosis is a genetically regulated process that is realized by the activation of death and prosurvival signaling cascades, and the interplay between these cascades determines whether the cell exposed to apoptotic stimuli dies or survives. Therefore, there is intense interest in understanding how the apoptotic machinery functions in embryos exposed to Teratogens. However, the interpretation of the results obtained remains problematic. The main problem is that excessive embryonic cell death, regardless of its nature, if uncompensated for, ultimately leads to maldevelopment or embryonic death. Therefore, we can easily interpret results when the intensity of teratogen-induced cell death and the severity or incidence of teratogeninduced anomalies directly correlate with each other. However, when teratogen-induced cell death is not followed by the formation of anomalies, a usual explanation is that teratogen-induced apoptotic cell death contributes to the renewal of teratogen-targeted cell populations by promoting the removal of injured cells. It is clear that such an explanation leaves vague the role of the antiapoptotic signaling mechanism (and, hence, the apoptotic machinery as a whole) with respect to protecting the embryo against teratogenic stress. In this review, we summarize the data from studies addressing the function of the apoptotic machinery in embryos exposed to Teratogens, and then we discuss approaches to interpreting the results of these studies. We hypothesize that activation of a proapoptotic signaling in teratogen-targeted cell populations is a necessary condition for an antiapoptotic signaling that counteracts the process of maldevelopment to be activated. If such a scenario is true, we need to modify our approaches to choosing molecular targets for studies addressing this topic. Birth Defects Research (Part C) 75: 353–361, 2005. © 2006 Wiley-Liss, Inc.
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immunoteratology i mhc involvement in the embryo response to Teratogens in mice
American Journal of Reproductive Immunology, 1995Co-Authors: Arkady Torchinsky, Amos Fein, V ToderAbstract:PROBLEM: The present study was carried out to evaluate an involvement of MHC-associated maternal immunoreactivity in response to environmental Teratogens. METHODS: Two chemicals, cyclophosphamide (CP) and 2,3-quinoxalinedimetanol, 1,4-dioxide (QD) were used as the reference Teratogens (RT). The response to these RT was investigated in syngeneically and allogeneically mated CBA/J and C57B1/6 mice. In part of C57B1/6 female mice, paraaortic lymph nodes were extirpated 14 days before mating to allogeneic or syngeneic males. Twenty or 40 mg/kg of CP or 300 or 600 mg/kg of QD were injected on day 12 and 9 of pregnancy, accordingly (vaginal plug indicates day 1 of pregnancy). On day 19 of pregnancy implantation sites, resorptions, live and dead fetuses were recorded and live fetuses were examined with methods routinely used in applied teratology. RESULTS: Both mice strains showed equal response to Teratogens but the RT-induced effect was significantly weaker in allogeneic than syngeneic mouse combinations. Extirpation of draining lymph nodes dramatically increased the sensitivity to RT in allogeneically mated females but failed to alter that of syngeneically mated ones. CONCLUSION: The results of this study suggest that fetomaternal MHC incompatibility exerts the favourable influence on teratological resistance of the embryo and MHC-associated immunoreactivity of “mother-fetus” axis is possibly responsible for this effect.
Richard F Keeler - One of the best experts on this subject based on the ideXlab platform.
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ALKALOID Teratogens FROM LUPINUS, CONIUM, VERATRUM, AND RELATED GENERA
Effects of Poisonous Plants on Livestock, 2013Co-Authors: Richard F KeelerAbstract:I. ABSTRACT Certain naturally occurring congenital deformities in domestic livestock are produced by quinolizidine, piperidine, and steroidal alkaloid Teratogens from members of the Lupinus, Conium, and Veratrum genera when plants are ingested during gestation. The considerable structural and configurational specificity among the Teratogens have allowed speculations about compounds from other plants that are probably Teratogens. Some of the speculations have been verified.
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quinolizidine and piperidine alkaloid Teratogens from poisonous plants and their mechanism of action in animals
Veterinary Clinics of North America-food Animal Practice, 1993Co-Authors: Kip E Panter, Richard F KeelerAbstract:Quinolizidine and piperidine alkaloid Teratogens from Lupinus,Conium, and Nicotiana genera have been identified as causes ofbirth defects in livestock induced by poisonous plants. Manydefects now known to be related to poisonous plant ingestionwere once thought to have a genetic origin. This suppositiondelayed diagnosis, reporting, and understanding of such birthdefects, because breeders and producers feared the news wouldmake it difficult to sell breeding stock. Defects caused by quinolizidineand piperidine Teratogens include cleft palate andcontracture-type skeletal defects such as arthrogryposis, scoliosis,torticollis, and kyphosis. Teratogens have been identified,differences in susceptibility to teratogenic compounds amonglivestock species have been elucidated, periods of gestation whenspecific types of birth defects occur have been determined, andinformation about mechanism of action has been developed.
