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At least 127 records · Page 7Linked to original sources

PubMed1995

Hemodynamic changes in HH stage 34 chick embryos after treatment with all-trans-retinoic acid.

To obtain insight into the hemodynamics of abnormal cardiac development, a chick embryo model was recently developed in which a spectrum of double outlet right ventricle was induced with all-trans-retinoic acid. In Hamburger and Hamilton (HH) stage 34 white Leghorn chick embryos, we simultaneously measured dorsal aortic flow velocities with a 20 MHz pulsed Doppler velocity meter and vitelline artery blood pressures with a servonull system. These measurements were performed in embryos treated at HH stage 15 with 1 microgram of all-trans-retinoic acid (n = 47), or with the solvent DMSO (n = 15), and in control embryos (n = 21). After the wave form recordings were collected, all embryos were examined histologically. Embryos treated with all-trans-retinoic acid showed in 15 cases hearts with a rightward positioned aorta with an additional subaortic ventricular septal defect and 32 cases without septation abnormalities of the heart. The hemodynamic data were correlated with the morphology. Statistical comparison was performed between control and experimental values. There was no significant discrepancy in hemodynamics of sham-operated and control embryos. Heart rate, peak systolic and mean velocities, peak systolic and mean blood flows, and peak acceleration and stroke volume were reduced in embryos treated with all-trans-retinoic acid (p < 0.01). Furthermore, in the presence of a subaortic ventricular septal defect the diameter of the dorsal aorta was reduced. Pressure readings were not statistically significant. Our findings suggest that the hemodynamic changes are the result of a decrease in cardiac contraction force.

Animals↗

PubMed2005

Ascorbic acid inhibits ROS production, NF-kappa B activation and prevents ethanol-induced growth retardation and microencephaly.

In this study, we established an embryo model to study the effects of ethanol on fetal development. When embryos of Xenopus laevis (the African clawed frog) were exposed to ethanol, the resultant tadpoles had significantly reduced brain sizes (microencephaly) and retarded growth rates. These effects, similar to those observed in human fetal alcohol syndrome (FAS), were dose- and time-dependent. We further showed that the antioxidant ascorbic acid (vitamin C) could inhibit the ethanol-induced reactive oxygen species (ROS) production and NF-kappaB activation and protect the ethanol-treated embryos against microencephaly and growth retardation. These results suggest the involvement of NF-kappaB and oxidative stress in ethanol-mediated developmental defects, and the potential use of ascorbic acid as a new and effective protective agent for FAS.

Animals↗

PubMed1999

The effects of lithium on vascular development in the chick area vasculosa.

The effects of lithium on vascular development were examined using the chick embryo area vasculosa in shell-less culture as an experimental model. Embryos were explanted after 48 h in ovo and LiC1 (50, 100, 150 and 200 microg in 10 microl water) was applied to the centre of the blastodisc. Controls were untreated or given equimolar amounts of NaCl. At 24 h and 48 h after treatment, untreated and NaCl controls were identical, having well developed extraembryonic vessels. At doses of 100 microg and greater, LiCl significantly inhibited normal vascular development and expansion of the area vasculosa in the majority of explants. In many specimens blood islands continued to form but their assembly into primitive vessels was prevented, indicating that lithium affects the mechanism regulating the assembly of vascular endothelium. At the same time the embryos were alive but retarded in development compared with controls. When LiCl (150 microg) was applied to cultures explanted after 72 h in ovo (when the primary vascular network had already formed through vasculogenesis) no adverse effects were seen. This suggests that lithium affects vasculogenesis but not angiogenesis. Treatment with myo-inositol completely reversed the effects of lithium in a time dependent manner indicating that the phosphatidylinositol second messenger cycle may be involved in the cellular events of vasculogenesis. Finally the results of this study show that the yolk sac vasculature is particularly vulnerable to lithium and the consequent effects of this interference on embryonic development are discussed.

Animals↗

PubMed1995

Increased cell death and reduced neural crest cell numbers in ethanol-exposed embryos: partial basis for the fetal alcohol syndrome phenotype.

Fetal alcohol syndrome (FAS) is characterized by growth retardation, craniofacial malformations, and heart and neural defects; the cellular and molecular mechanism(s) responsible for ethanol's teratogenicity remains unknown. Although the phenotype suggests that prenatal ethanol exposure perturbs neural crest cell development, direct proof that these cells are an in utero target is still lacking. Previous research suggested that cranial neural crest cells are eliminated by ethanol-induced apoptosis. We tested this hypothesis using a chick embryo model of FAS. A single dose of ethanol, chosen to achieve a concentration of 35-42 mg/dl, was injected in ovo at gastrulation and resulted in growth retardation, craniofacial foreshortening, and disrupted hindbrain segmentation. Ethanol exposure enhanced cell death within areas populated by cranial neural crest cells, particularly in the hindbrain and craniofacial mesenchyme. In contrast, control embryos had limited cell death within these regions. Subsequent immunolabeling with neural crest cell-specific antibody revealed that ethanol treatment resulted in fewer neural crest cell numbers, whereas neural crest migration patterns were unaffected by ethanol. These results suggest that prenatal ethanol exposure leads to loss of cranial neural crest cells. Such a loss could result, in part, in the phenotype characteristic of FAS.

Animals↗

PubMed1987

Superiority of the chimpanzee animal model to study the pathogenicity of known Mycoplasma pneumoniae and reputed mycoplasma pathogens.

As far as we know, humans are the only known natural hosts for M. pneumoniae disease. Whereas volunteer studies have provided useful data on the pathogenesis of disease and efficacy of vaccines, experimentally inducing disease in humans raises serious ethical questions and has become increasingly difficult to defend. Thus, there is a genuine need for a satisfactory animal model to study M. pneumoniae disease. Using the cotton rat and developing chick embryo models, Eaton and co-workers (9-13) have clearly shown that the infectious "Eaton agent" was the cause of primary atypical pneumonia. After the causative agent was identified as M. pneumoniae (14), more definite and quantitative studies were possible. The hamster animal model has provided most of our information on the pathogenicity of strains, the pathogenesis of disease and the potency of inactivated vaccines. However, protective data obtained in hamsters immunized with the TS mutant vaccines did not correlate with data obtained in humans, raising concern regarding the use of the hamster animal model to evaluate the potency of live TS vaccines. The chimpanzee animal model has a number of advantages. Chimpanzees become clinically ill, show positive X-ray findings, and develop cold agglutinin titers. In fact, the experimentally induced disease in chimpanzees is remarkably similar to naturally occurring primary atypical pneumonia in patients. Because of the close genomic relationship, immunologic reagents prepared and used for human studies can also be used successfully in chimpanzee studies. The chimpanzee model also has some serious disadvantages. They are expensive to house and maintain and are generally not available to the scientific community. Nonetheless, chimpanzees are probably the best, most meaningful animal models established thus far to examine the infectious process, the immune response and the pathogenesis of this disease and to determine approaches to effective therapy and immunization of diseases produced by known pathogens, like M. pneumoniae, as well as reputed mycoplasma pathogens, such as M. genitalium and M. hominis.

Animals↗

PubMed2006

Cathepsin Cs are key for the intracellular survival of the protozoan parasite, Toxoplasma gondii.

Cysteine proteases play key roles in apicomplexan invasion, organellar biogenesis, and intracellular survival. We have now characterized five genes encoding papain family cathepsins from Toxoplasma gondii, including three cathepsin Cs, one cathepsin B, and one cathepsin L. Unlike endopeptidases cathepsin B and L, T. gondii cathepsin Cs are exopeptidases and remove dipeptides from unblocked N-terminal substrates of proteins or peptides. TgCPC1 was the most highly expressed cathepsin mRNA in tachyzoites (by real-time PCR), but three cathepsins, TgCPC1, TgCPC2, and TgCPB, were undetectable in in vivo bradyzoites. The specific cathepsin C inhibitor, Gly-Phe-dimethylketone, selectively inhibited the TgCPCs activity, reducing parasite intracellular growth and proliferation. The targeted disruption of TgCPC1 does not affect the invasion and growth of tachyzoites as TgCPC2 is then up-regulated and may substitute for TgCPC1. TgCPC1 and TgCPC2 localize to constitutive secretory vesicles of tachyzoites, the dense granules. T. gondii cathepsin Cs are required for peptide degradation in the parasitophorous vacuole as the degradation of the marker protein, Escherichia coli beta-lactamase, secreted into the parasitophorous vacuole of transgenic tachyzoites was completely inhibited by the cathepsin C inhibitor. Cathepsin C inhibitors also limited the in vivo infection of T. gondii in the chick embryo model of toxoplasmosis. Thus, cathepsin Cs are critical to T. gondii growth and differentiation, and their unique specificities could be exploited to develop novel chemotherapeutic agents.

Amino Acid Sequence↗

PubMed1997

Modelling the growth of salmonid embryos

A mechanistic model for the growth of salmonid embryos (prior to feeding) is developed with coupled differential equations describing anabolism and catabolism. The equations model changes in embryo and yolk sac masses in which the flux of nutrients to the embryo is controlled by geometric properties of the embryo and yolk. The rate parameter describing this flux is a well defined function of temperature. Water absorption is also a factor in determining mass. The model, describing the size and time-to-arrival at developmental stages, is fit to chinook salmon growth data from fertilization to complete yolk absorption.Copyright 1997 Academic Press Limited Copyright 1997 Academic Press Limited

Journal Article↗

PubMed2003

Studies on the toxicity of Punica granatum L. (Punicaceae) whole fruit extracts.

Current investigation focuses on the toxicity evaluation of whole fruit hydroalcoholic extract of Punica granatum L. (Punicaceae), used in Cuban traditional medicine a.o. for the treatment of respiratory diseases. Previous findings on the anti-influenza activity of Punica granatum extracts has given support to the ethnopharmacological application. In our study, in chick embryo model, it was found that doses of the extract of less than 0.1 mg per embryo are not toxic. The LD50 of the extract, determined in OF-1 mice of both sexes after intraperitoneal administration, was 731 mg/kg. Confidence limits were 565-945 mg/kg. At the doses of 0.4 and 1.2 mg/kg of extract, the repeated intranasal administration to Wistar rats produced no toxic effects in terms of food intake, weight gain, behavioural or biochemical parameters, or results of histopathological studies. We conclude that toxic effects of Punica granatum fruit extract occurred at higher doses than those effective in the models where the anti-viral activity has been studied or than those doses used in Cuban folk medicine.

Abnormalities, Drug-Induced↗

PubMed2004

Control of retinoic acid synthesis and FGF expression in the nasal pit is required to pattern the craniofacial skeleton.

Endogenous retinoids are important for patterning many aspects of the embryo including the branchial arches and frontonasal region of the embryonic face. The nasal placodes express retinaldehyde dehydrogenase-3 (RALDH3) and thus retinoids from the placode are a potential patterning influence on the developing face. We have carried out experiments that have used Citral, a RALDH antagonist, to address the function of retinoid signaling from the nasal pit in a whole embryo model. When Citral-soaked beads were implanted into the nasal pit of stage 20 chicken embryos, the result was a specific loss of derivatives from the lateral nasal prominences. Providing exogenous retinoic acid residue development of the beak demonstrating that most Citral-induced defects were produced by the specific blocking of RA synthesis. The mechanism of Citral effects was a specific increase in programmed cell death on the lateral (lateral nasal prominence) but not the medial side (frontonasal mass) of the nasal pit. Gene expression studies were focused on the Bone Morphogenetic Protein (BMP) pathway, which has a well-established role in programmed cell death. Unexpectedly, blocking RA synthesis decreased rather than increased Msx1, Msx2, and Bmp4 expression. We also examined cell survival genes, the most relevant of which was Fgf8, which is expressed around the nasal pit and in the frontonasal mass. We found that Fgf8 was not initially expressed along the lateral side of the nasal pit at the start of our experiments, whereas it was expressed on the medial side. Citral prevented upregulation of Fgf8 along the lateral edge and this may have contributed to the specific increase in programmed cell death in the lateral nasal prominence. Consistent with this idea, exogenous FGF8 was able to prevent cell death, rescue most of the morphological defects and was able to prevent a decrease in retinoic acid receptorbeta (Rarbeta) expression caused by Citral. Together, our results demonstrate that endogenous retinoids act upstream of FGF8 and the balance of these two factors is critical for regulating programmed cell death and morphogenesis in the face. In addition, our data suggest a novel role for endogenous retinoids from the nasal pit in controlling the precise downregulation of FGF in the center of the frontonasal mass observed during normal vertebrate development.

Acyclic Monoterpenes↗

PubMedDate not supplied

Metastatic potential of MDA435 and Hep2 cell lines in chorioallantoic membrane (CAM) model.

Chick embryo chorioallantoic membrane model is a very sensitive assay for studying metastasis in vivo. In this organism, tissue barriers provide a real support to demonstrate the infiltration pathway of two human tumoral cell stains: a line of breast adenocarcinoma (MDA435), and a line of larynx epidermoid carcinoma (Hep2). We studied the metastatic potential of these cells to migrate from the upper chorioallantoic membrane (CAM) to the lower CAM, using as marker a human p53 primer, known for flanking exclusively a human region of exon 8. Our results show that both cell lines possess the ability to migrate from the inoculation site (on the upper CAM) to distant sites of the CAM (lower CAM). A difference in the pattern of migration among the two cell lines was also observed. While Hep2 cells showed a uniform migration from the inoculation site, MDA435 cell line showed a different migration pattern consistent with the idea of two different populations within the same cell line.

Allantois↗

PubMed2006

Design, synthesis, and biological evaluation of 3,4-diarylmaleimides as angiogenesis inhibitors.

The new analogue 2 of combretastatin A-4 was discovered to be an inhibitor of tubulin polymerization with an IC50 of 7.6 microM and reduced angiogenesis in the in vivo chick embryo model. Interestingly, in a series of 2,3-diarylmaleimides closely related to this lead, no other compound was found to be active in the tubulin polymerization assay. However, by screening in the in vivo chick embryo assay 10 was identified as a potent angiogenesis inhibitor indicating an alternative target. Indeed, molecular modeling studies suggest a reasonable binding mode of 10 at the ATP-binding site of the model kinase CDK2. Motivated by these results, analogues of 10 were screened for inhibitory activity in a panel of 12 selected protein kinases and a high affinity of 10 to VEGF-R2 was found showing an IC50 of 2.5 nM. Structure-activity relationships (SAR) for this compound series with the isolated enzyme and equivalent antiangiogenic activity in the chick embryo assay are presented herein.

Adenosine Triphosphate↗

PubMed1995

Presence of activated macrophages in a murine model of early embryo loss.

PROBLEM: Even though our knowledge of the phenomenon at play at the fetoplacental interface has greatly advanced during the past years, a complete understanding of the reasons why the developing embryo is not rejected by maternal immune effector cells remains largely unknown. METHODS: We have used immunohistochemistry with the macrophage-specific markers F4/80 and MHC II to study the relationship between decidual infiltration and resorption in murine models of embryo loss between days 6 and 10 of gestation. RESULTS: Analysis of day 8 CBA/J x DBA/2 pregnancies has revealed 2 distinct populations of embryos. The majority (69.4%) expressed low levels of F4/80+ cells, but a minority (30.6%) expressed much higher level of the macrophage marker. In FBA/J x BALB/c, most embryos (91.7%) expressed low numbers of F4/80+ cells. As earlier experiments established that products of activated macrophages (TNF-alpha and nitric oxide) were implicated in embryo loss in this model, the activation status of the F4/80+ macrophages was assessed through the cell surface expression of MHC II. Again, a similar association was established: 30.6% of the CBA/J x DBA/2 embryos were infiltrated by significantly more MHC II+ cells than the control CBA/J x BALB/c mating. Finally, when coordinate expression of F4/80, MHC II and CD11b was assessed, it was found that an embryo significantly infiltrated by cells bearing one of the 3 markers was also heavily infiltrated by cells bearing the 2 other markers. CONCLUSIONS: This study has shown that the augmented infiltration of the deciduum with maternal macrophages is an early event which precedes spontaneous abortion of the early embryo.

Animals↗

PubMed2005

Experimental diabetes model in chick embryos treated with streptozotocin.

The aim of the present study was to investigate whether diabetes model can be made by treatment of streptozotocin (STZ) in chick embryos and this model can be used to predict the effect of drug. When STZ (0.3 mg/egg) was injected into the albumen of fertile eggs on the 14th day of incubation, level of blood glucose significantly increased than that of the control on the 17th day of incubation, and level of serum insulin significantly decreased. In addition, the enhanced level of blood glucose in STZ-treated embryos reduced by injection of human insulin. In conclusion, STZ-treated embryos may be applicable to evaluate human insulin and anti-diabetes drugs as an experimental diabetes model.

Animals↗

PubMed2005

Anti-proliferative and anti-leukemic activity of DDE46 (compound WHI-07), a novel bromomethoxylated arylphosphate derivative of zidovudine, and related compounds. Studies using human acute lymphoblastic leukemia cells and the zebrafish model.

The anti-proliferative effects of a novel bromomethoxylated arylphosphate derivative of zidovudine (compound DDE46, CAS 213982-96-8) were first examined in a zebra fish embryo model. DDE46 blocked the cell division at the 2-cell stage of the embryonic development followed by total cell fusion. DDE46 also inhibited the proliferation of the leukemic cell lines NALM-6 and MOLT-3. DDE46 enhanced the activity of the pro-apoptotic enzymes Caspase-3, Caspase-6, Caspase-8, and Caspase-9 leading to the apoptotic death of the leukemic cell line Jurkat. These results justify the further development of this agent as a new anti-leukemic drug candidate.

Animals↗

PubMed1980

Prevalence of type-specific group B streptococcal antibody in pregnant women.

Immunoglobulin G antibody against the four major serotypes of group B streptococcus was measured by indirect immunofluorescence in the sera of 200 consecutive pregnant women seen in the obstetric screening clinic of an urban teaching hospital. Antibody was detectable in 26% of undiluted sera against serotype Ia, 52% against serotype Ib, 82% against serotype II, and 45% against serotype III. Only 9% had antibody against all four GBS types. When serotype-specific antibody prevalences in 108 women with GBS vaginal colonization were compared with prevalences in noncolonized women, only women colonized with GBS type Ia were more likely to have antibody against Ia than noncolonized women. Antibody prevalences in sera from 54 mothers whose infants developed invasive GBS disease were significantly lower than those in colonized or noncolonized women. Since low titers of IF antibody to GBS III were present in some sera from mothers of infected infants, the data were analyzed based on IF antibody titers associated with passive protection in a chick embryo model of GBS septicemia. None of the sera from mothers of infected infants had antibody levels associated with chick embryo protection. Less than 10% of women had titers associated with chick embryo protection. These data suggest that the majority of pregnant women lack immunity to GBS, regardless of colonization status.

Adult↗

PubMed1997

The effect of the oviduct, uterine, and in vitro environments on zona thinning in the mouse embryo.

OBJECTIVE: To evaluate the impact of the oviduct, uterine, and in vitro environments on zona pellucida thinning in the mouse embryo. DESIGN: Female mice were stimulated with pregnant mare serum gonadotropin and mated and hCG injection. Unilateral oviduct ligation was performed on day 2 of gestation using the dorsal approach. The mice were divided into equal groups and killed on days 2, 3, 4, 5, and 10 of gestation. In vitro incubated embryos served as controls. Average daily zona thickness measurements were subjected to analysis of variance and paired Student's t-test. SETTING: The laboratory of the assisted reproductive program of Rush University Medical Center. MAIN OUTCOME MEASURE(S): Progressive daily decrease in average zona thickness. RESULT(S): Zona measurements of embryos flushed out of uterine horns, ligated oviducts, and in vitro incubation demonstrated statistically significant decreases in zona thickness, from 9.6 +/- 1.6 microns (day 3) to 6.0 +/- 0.8 microns (day 5), from 11.6 +/- 2.2 microns (day 2) to 6.0 +/- 1.6 microns (day 5), and from 11.1 +/- 2.0 microns (day 2) to 6.0 +/- 1.6 microns (day 5), respectively. There were no differences in average zona thickness for embryos in the same cell stage and same protocol day in all three locations. CONCLUSION(S): Zona thinning seems to be induced primarily by the dividing embryo before implantation. A substantial tubal and uterine contribution to zona thinning was not detected in this mouse embryo model.

Animals↗

PubMed1998

The interaction of ethanol and vitamin A as a potential mechanism for the pathogenesis of Fetal Alcohol syndrome.

The mechanism of the fetal embryopathology resulting from ethanol ingestion during pregnancy is not established. This review summarizes recent research on the interaction of ethanol and vitamin A in models that explore if an interaction between these two compounds might potentially be the mechanism for fetal alcohol syndrome. The rationale for this hypothesis includes the known facts that: (1) in adults, ethanol ingestion alters vitamin A metabolism and tissue distribution; (2) there are many phenotypic similarities between fetal alcohol syndrome and malformations of both vitamin A toxicity and deficiency; and (3) the vitamin A metabolite, retinoic acid (RA), is a potent mediator in embryogenesis and differentiation. One interaction that could possibly alter fetal development is that the synthesis of RA from retinol, catalyzed by alcohol dehydrogenase, might be competitively inhibited by ethanol leading to RA deficiency. Controversy over this hypothesis continues. Another model demonstrates in vivo effects of pregnant rat mother's ethanol consumption on retinol, retinyl ester, RA content, RA receptor (RAR) binding, and the levels of RAR expression in developing fetal organs. The variable responses in this model still need clarification, and specific defects resulting from specific RAR changes have not yet been identified. In a quail embryo model, ethanol treatment mimics vitamin A deficiency, and RA appears to prevent the adverse effects of ethanol. Finally, RA and ethanol reverse or block each other's effects in studies on isolated neuroblastoma cells. Taken together, these experiments show definite interactions between ethanol and vitamin A. Further studies are needed to determine if any of these mechanisms significantly contribute to prenatal ethanol consumption embryopathy; but, clearly this hypothesis is gaining experimental support.

Adult↗

PubMed1989

[The chick embryo as a model of fetal surgery: intestinal atresia].

Aiming at depicting the advantages of chick embryo as a model of fetal surgery we report on our experience of 402 operations carried out in an attempt to induce fetal intestinal obstruction. We have used fertile domestic hen (gallus gallus) eggs incubated at 37.5 degrees with 80% humidity and turned every hour. At the 12th day of incubation we coagulated, after exposing the umbilical cord, a small bowel loop in the physiologic umbilical hernia through a 1 cm-wide opening in the shell which was then sealed with plastic sterile adhesive. After sacrifice at the 15th day of the 76 surviving embryos (19%) we found type I intestinal atresia with localized meconium peritonitis and dilated proximal loop in 46 cases. In 3 out of them there was, like in some human newborns with intestinal obstruction, increased amount of bile-stained amniotic fluid. Both macroscopic and microscopic findings were identical to those usually found in human atresia and in that experimentally induced in fetus of other animal species. We firmly believe that our model is as good as any other for this purpose and, at the same time, it is cheaper and easier to handle.

Animals↗