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At least 91 records · Page 5Linked to original sources
PubMed1986

Passage of herpes simplex virus type 1 on chick embryo fibroblasts confers virulence for chick embryos.

The pathogenesis of chorioallantoic membrane (CAM) infection with herpes simplex virus 1 and 2 (HSV-1 and HSV-2) as well as chick embryo fibroblast (CEF) passaged HSV-1 was studied. It was found that HSV-2 is at least a million-fold more virulent than HSV-1 as measured by pfu/LD50 ratios for the embryo. Serial passage of HSV-1 in vitro on CEF cells selected for a virus (CEFP10) which, unlike its parental HSV-1 strain, is able to kill the embryo. The restriction endonuclease maps of CEFP10 and its parental strain are indistinguishable and the mechanism of the increased virulence of CEFP10 was demonstrated to be its enhanced replication in chick embryo cells both in vivo and in vitro. In contrast, despite its inferior replicative ability, HSV-2 was found to have a biologically important specific invasiveness function that is not simply related to overall viral replication. Finally, the ability to isolate HSV-1 (CEFP10) virulent for the chick embryo after passage in vitro illustrates that tissue culture passage of HSV in appropriate cells may actually increase virulence for the animal host.

Animals↗
PubMed1980

Study of some enzyme activities in cultured chick embryo brain nerve cells treated by chick embryo brain extracts.

Brain extracts from 8-day-old chick embryos have been shown to influence morphological development of dissociated brain cells from 7-day-old chick embryos in culture. Stimulatory effects on size of the neuronal somas and on growth of long processes were observed by adding the cytosol of the brain extract or the dialysate of the cytosol. These morphological changes parallel modifications of various enzyme activities according to the age of the cultures. Adenyl cyclase, (Na+,K+)- and Mg2+-ATPase, 5'-nucleotidase, choline acetyltransferase, and acetylcholinesterase activities were studied between 5 and 14 days of culture. Adenyl cyclase activity was strongly stimulated at 8 days by both extracts. (Na+,K+)- and Mg2+-ATPase activities were stimulated in 8-day-old cultures only by the dialysate. 5'-Nucleotidase activity was stimulated in 8-day-old cultures by the dialysate and in 11-day-old cultures by both extracts. Choline acetyltransferase activity was stimulated by the cytosol in 8-day-old cultures and by the dialysate in 11-day-old cultures. The total acetylcholinesterase activity was higher in 8-, 11-, and 14-day-old cultures treated with the cytosol. When the cells were treated with the dialysate, the activity was only higher in 14-day-old cultures. We also found that following the addition of brain extracts, the specific activity of the enzymes we studied was enhanced and became close to the values found in vivo during embryogenesis. Thus in parallel to the morphological modifications observed in nerve cell cultures treated by embryo brain extracts, biochemical variations especially involved in synaptogenesis and membrane development could be measured.

Acetylcholinesterase↗
PubMed1981

Role of haem in the induction of cytochrome P-450 by phenobarbitone. Studies in chick embryos in ovo and in cultured chick embryo hepatocytes.

The role of haem synthesis during induction of hepatic cytochrome P-450 haemoproteins was studied in chick embryo in ovo and in chick embryos hepatocytes cultured under chemically defined conditions. 1. Phenobarbitone caused a prompt increase in the activity of 5-aminolaevulinate synthase, the rate-limiting enzyme of haem biosynthesis, and in the concentration of cytochrome P-450. This induction response occurred without measurable initial destruction of the haem moiety of cytochrome P-450. 2. When intracellular haem availability was enhanced by exogenous haem or 5-aminolaevulinate, phenobarbitone-medicated induction of cytochrome P-450 was not affected in spite of the well known repression of 5-aminolaevulinate synthase by haem. These data are consistent with the concept that haem does not regulate the synthesis of cytochrome P-450 haemoproteins. 3. Acetate inhibited haem biosynthesis at the level of 5-aminolaevulinate formation. When intracellular haem availability was diminished by treatment with acetate, phenobarbitone-medicated induction was decreased. 4. This inhibitory effect of acetate on cytochrome P-450 induction was reversed by exogenous haem or its precursor 5-aminolaevulinate. These data suggest that inhibition of haem biosynthesis does not decrease synthesis of apo-cytochrome P-450. Moreover, they indicate that exogenous haem can be incorporated into newly formed aop-cytochrome P-450.

5-Aminolevulinate Synthetase↗
PubMed1982

Labelling of prolyl hydroxylase tetrameric subunits in freshly isolated chick-embryo tendon cells and in certain chick-embryo tissues in vivo.

The labelling of the subunits of prolyl 4-hydroxylase tetramers was studied in freshly isolated chick-embryo tendon cells and in chick-embryo tissues. In the former both the alpha- and beta-subunits of the tetramer were labelled during a 4 h labelling and 2 h chase period, although the radioactivity in the beta-subunit was much lower than in the alpha-subunit. The corresponding subunits of the enzyme from 12-day chick-embryo cartilaginous bone and heart were labelled in 7 h, again the beta-subunit much less than the alpha-subunit, the ratio of radioactivity in the beta-subunit to that in the alpha-subunit (beta/alpha-radioactivity) being 0.20 and 0.32 respectively. The beta/alpha-radioactivity then increased almost linearily with time between 7 and 24 h, by 9.5-fold in the cartilaginous bone and 3-fold in the heart, and beta/alpha-radioactivity values above 1.0 were reached. The free beta-subunit-size protein (the beta'-protein), which is also present in cells, had been labelled quite heavily by 7 h. The beta/alpha-radioactivity at 7h, determined in four tissues with different ratios of prolyl hydroxylase tetramers to total immunoreactive protein (tetramer percentage), was low in tissues with a high tetramer percentage. It is thus proposed that only a minor fraction of the beta'-protein must be processed to the tetrameric beta-subunit and utilized in the synthesis of the prolyl 4-hydroxylase tetramers.

Animals↗
PubMed1992

In vitro evaluation of plasticizer activity on the growth and metabolism of chick embryo fibroblasts and on the development of chick embryo lungs.

Administration of di(2-ethylhexyl) phthalate (DEHP) to primary cultures of chick embryo fibroblasts brought about a decrease in cell proliferation rate after 48 h and an inhibition of both DNA and protein synthesis measured by [3H]thymidine and [3H]leucine, respectively, after 48 h. The growth of chick embryo lung rudiments in vitro was also depressed by DEHP treatment. Lung rudiment were smaller in DEHP-treated embryos after 6 days' treatment. These results indicate that DEHP has a cytostatic effect on embryonic cells and tissues.

Animals↗
PubMed1994

Distribution of TNF alpha-like proteins correlates with some regions of programmed cell death in the chick embryo.

Early chick embryos have previously been shown to express tumor necrosis factor-alpha-cross-reactive proteins (TNF alpha-CRPs) in a developmentally regulated manner, thus implicating these proteins in programmed cell death and in tissue remodeling. In this study, cells undergoing DNA fragmentation have been identified, using terminal deoxynucleotide transferase (TdT) mediated dUTP-biotin nick-end-labeling (TUNEL), during the embryonic development of the chick, between stages 18 and 29. DNA fragmentation is indicative of cells undergoing programmed cell death. TUNEL-positive cells were identified in several well documented areas of programmed cell death, including the limb buds, the heart, spinal motoneurons, dorsal root ganglia, and the ventral horn of the neural tube. In addition, other areas of cell death were identified including the floor plate and the mesonephros. In several locations, a close correlation was noted between the presence of TUNEL-positive cells and regions of TNF alpha-immunoreactivity. These regions included the ventral horn and marginal zone of the neural tube, spinal motoneurons, paravertebral ganglia, parts of the myotome, mesenchyme of the body wall, and the mesonephros. In addition, using the TNF alpha-sensitive L929-8 bioassay it was shown that homogenate of stage 18 chick embryos is cytotoxic to L929-8 cells and that this toxicity can be reduced using neutralizing antibodies to mouse TNF alpha. This bioassay allowed us to estimate the mean concentration of TNF alpha-like activity in embryo homogenate, which is within the range of physiological (pg/ml) levels of TNF alpha found in other systems. These results suggest that proteins with TNF alpha-like activity may have a role in programmed cell death in some tissues during early chick embryo development.

Animals↗