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Biomedical subjects

J Y Chou

Publications and source records attributed to J Y Chou.

At least 145 records · Page 8Linked to original sources
PubMed1980

Synthesis of first trimester placental alkaline phosphatase in cultured human term placental cells.

Alkaline phosphatase activity in human placental cells transformed by a tsA mutant of simian virus 40 (SV40) can be greatly induced by growing these cells at 40 degrees C, the temperature at which the tsA transformants regain their nontransformed phenotype. The induction of alkaline phosphatase in these cells requires the synthesis of both RNA and protein. The induced alkaline phosphatase from a SV40 tsA30 mutant-transformed term placental cell line (TPA30-1) was purified, characterized, and compared with alkaline phosphatase from term placenta and first trimester placenta. The form of alkaline phosphatase found in TPA30-1 cells differs from the phosphatase of term placenta in physiochemical and immunological properties. The TPA30-1 phosphatase is, however, indistinguishable from the alkaline phosphatase of human first trimester placenta by several criteria, including electrophoretic mobility, apparent molecular weight (Mr = 165,000), size of monomeric subunit (Mr = 77,000), heat lability, and sensitivity to inhibition by amino acids and EDTA. In addition, alkaline phosphatase from both TPA30-1 cells and first trimester placenta can be inactivated by antiserum to liver alkaline phosphatase but not by antiserum to term placental alkaline phosphatase. The induction of first trimester phosphatase in cells derived from term placenta provides a system for the study of alkaline phosphatase gene regulation in human placenta.

Alkaline Phosphatase↗
PubMed1980

Establishment of a fetal rat liver cell line that retains differentiated liver functions.

Fetal rat liver cells were transformed with a temperature-sensitive A mutant (tsA255) of simian virus 40. A CLONAL CELL LINE, RLA255-4, which was temperature sensitive in the maintenance of the transformed phenotype, was isolated. This cell line expressed the transformed phenotype (rapid growth, high cell density, overgrowth of normal cells, and cloning in soft agar) at the permissive temperature (33 degrees C) and the nontransformed phenotype (slower growth, lower saturation density, decreased efficiency of overgrowth of normal cells, and lower cloning efficiency in soft agar) at the restrictive temperature (40 degrees C). The tsA255-transformed cells expressed differentiated liver functions under controllable conditions. At the permissive temperature, they produced low levels of albumin and transferrin, whereas at the restrictive temperature the transformed phenotype was lost and the production of these hepatic proteins was greatly enhanced. RLA255-4 cells contained functional receptors for glucagon, as shown by the stimulation of intracellular cyclic AMP accumulation by glucagon. The response to glucagon was dose dependent (Kact = 5 x 10(-8) M) and could be demonstrated in cells grown at both permissive and restrictive temperatures after 7 days in culture (i.e., at a cell density of approximately 4 x 10(5) cells per cm2 or higher). Addition of cortisol to the culture medium enhanced the glucagon response selectively at the restrictive temperature.

Albumins↗
PubMed1980

Effects of sodium butyrate and 5-bromo-2'-deoxyuridine on the synthesis of human chorionic gonadotropin in human placental cells transformed by tsA mutants of simian virus 40.

The synthesis of hCG and its subunits was studied in simian virus 40 (SV40) tsA mutant-transformed human first trimester and term placental cells at 33 C (the temperature at which the cells have the transformed phenotype) and 40 C (the temperature at which the temperature-sensitive tsA transformants regain their nontransformed phenotype). In the presence of sodium butyrate at 33 C, synthesis of both hCG and hCG alpha was greatly induced in the tsA transformants. at 40 C, hCG synthesis was induced by sodium butyrate, although to a lesser extent than at 33 C. Yet, hCG alpha synthesis was inhibited by sodium butyrate at 40 C. In the presence of 5-bromo-2'-deoxyuridine (BrdUrd) at 33 C, hCG synthesis was not affected in the transformed first trimester placental cells and was induced in the transformed term placental cells. In the presence of BrdUrd at 40 C, hCG synthesis was induced in both forms of placental cells. The synthesis of the free hCG alpha-subunit appeared to be controlled differently. At 33 C, hCG alpha synthesis was also induced by BrdUrd. At 40 C, however, hCG alpha synthesis was inhibited by BrdUrd. hCG synthesis was induced and hCG alpha synthesis was inhibited by sodium butyrate and BrdUrd in the tsA-transformed placental cells grown at 40 C. Whereas the synthesis of both hCG and hCG alpha in choriocarcinoma cells has been reported to be inhibited by both sodium butyrate and BrdUrd. Our data indicate that the effects of sodium butyrate and BrdUrd on the production of hCG, but not hCG alpha, were different in the SV40 tsA-transformed placental cells and choriocarcinoma cells.

Bromodeoxyuridine↗
PubMed1980

Effects of adenosine cyclic nucleotides on the synthesis of human chorionic gonadotropin in transformed human placental cells.

The synthesis of human chorionic gonadotropin (HCG) and its subunits was studied in simian virus 40 (SV40) tsA mutant-transformed human first-trimester and term placental cells at 33 degrees (the temperature at which the cells have the transformed phenotype) and at 40 degrees (the temperature at which the tsA transformants regain their nontransformed phenotype). 8-Bromo cyclic adenosine 3':5'-monophosphate (8BrcAMP) and dibutyryl cyclic adenosine 3':5'-monophosphate (Bt2cAMP) greatly induced the synthesis of human chorionic gonadotropin alpha (HCG alpha) with little or no stimulation of the synthesis of HCG in transformed placental cells grown at 33 degrees or 40 degrees. The ratio of HCG alpha to HCG in these cells, therefore, increased in the presence of either nucleotide. 8BrcAMP and Bt2cAMP also greatly induced the synthesis of HCG alpha in nontransformed secondary placental cells (at 6th to 20th passage), although the synthesis of HCG was not detectable in these cells under the experimental conditions used. The synthesis of HCG as well as HCG alpha was stimulated in choriocarcinoma cells by 8BrcAMP and Bt2cAMP. The ratio of HCG alpha to HCG in uninduced choriocarcinoma cells increased during growth in culture. 8BrcAMP stimulated the synthesis of HCG preferentially in these cells, thus decreasing the ratio of HCG alpha to HCG. Our data indicate that adenosine cyclic nucleotides have different effects on the production of HCG but not on HCG alpha in SV40 tsA-transformed placental cells and choriocarcinoma cells.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1979

Characterization of alkaline phosphatases from human first trimester placentas.

Alkaline phosphatase from human first trimester placentas was purified, characterized, and compared with alkaline phosphatases from term placenta and liver. Three forms of first trimester placental alkaline phosphatase (I, IIa, and IIb) were isolated; their relative amounts were 35%, 39%, and 26%, respectively. Phosphatases I and IIa were found to be dimers, whereas phosphatase IIb appeared to be a tetramer consisting of two dimers of phosphatase I or IIa. Phosphatase I was indistinguishable from liver phosphatase by several criteria including apparent molecular weight (Mr = 165,000), size of the monomeric subunit (Mr = 77,000), heat liability, insensitivity to inactivation by antiserum against term placental alkaline phosphatase, and sensitivity to inactivation by antiserum against liver alkaline phosphatase. In addition, phosphatase I and liver phosphatase were equally sensitive to inhibition by amino acids, levamisole, l-p-bromotetramisole, and EDTA. Phosphatase IIa, in contrast, was indistinguishable from term placental alkaline phosphatase by the same criteria: apparent molecular weight (Mr = 115,000), size of the monomeric subunit (Mr = 63,000), heat stability, inactivation by antiserum against term placental alkaline phosphatase, and sensitivity to inhibition by various compounds. These findings clearly demonstrate the existence of two distinct placental alkaline phosphatases, one (phosphatase I) specific for the first trimester placenta and the other (phosphatase IIa) occurring in both first trimester and term placentas.

Alkaline Phosphatase↗
PubMed1979

Regulation of the induction of alkaline phosphatase in choriocarcinoma cells by sodium butyrate.

Alkaline phosphatase is induced in human choriocarcinoma cells by short-chain fatty acids, especially sodium butyrate. This fatty acid increases the phosphatase activity immediately and in a nearly linear fashion. Only phosphatase with an alkaline pH optimum is induced. Both the induced alkaline phosphatase and the basal enzyme are precipitated by antiserum against term-placental alkaline phosphatase, but the choriocarcinoma phosphatase is less stable to heating than is the term-placental enzyme. The induction of alkaline phosphatase activity requires cellular synthesis of protein, RNA and DNA. The regulation of induction probably occurs at the transcriptional level.

Alkaline Phosphatase↗
PubMed1978

Regulation of the synthesis of human chorionic gonadotropin by strains of HeLa cells in culture.

Thirty-seven strains of HeLa cells were examined for their ability to synthesize human chorionic gonadotropin (hCG) and its alpha subunit (hCG-alpha) in culture. Synthesis of hCG-alpha and hCG also was investigated in the presence of sodium butyrate and 5-bromo-2'-deoxyuridine (BrdUrd). All HeLa strains synthetized hCG-alpha in culture. Sodium butyrate increased the synthesis of hCG-alpha in all HeLa cells; BrdUrd increased synthesis in 32 of the 37 strains examined. Although few HeLa strains synthesized hCG in the absence of inducers, hCG was detected in most strains in the presence of sodium butyrate. The synthesis of hCG and its alpha subunit is, therefore, a stable genetic characteristic of HeLa cells.

Bromodeoxyuridine↗
PubMed1978

Human placental cells transformed by tsA mutants of simian virus 40: a model system for the study of placental functions.

Human placental cells were transformed with wild-type simian virus 40 (SV40) and temperature-sensitive SV40 mutants of the A and B classes. Four criteria for transformation were used: decreased generation time, increased saturation density, increased efficiency of growth on plastic, and ability to overgrow a nontransformed monolayer. Cell lines transformed by tsA mutants lost the transformed phenotype at the restrictive temperature (40 degrees); therefore, the A function of SV40 is required for the maintenance of the transformed phenotype activity, an inhibition of human chorionic gonadotropin synthesis, and an increase in thymidine kinase activity were seen when human placental cells transformed by wild-type or tsB mutants of SV40 were grown at 33 degrees or 40 degrees and when tsA transformants were grown at 33 degrees. When tsA transformants were grown at 40 degrees, alkaline phosphatase activity and human chorionic gonadotropin synthesis were greatly stimulated and thymidine kinase activity was greatly reduced, approximating their levels in the placenta.

Alkaline Phosphatase↗
PubMed1978

Establishment of clonal human placental cells synthesizing human choriogonadotropin.

Seven clonal human placental cell lines were established by transformation of human first-trimester placental cells with simian virus 40. These transformed cells synthesized native human choriogonadotropin (chorionic gonadotropin) (hCG) as well as the free alpha and beta subunits of hCG. The amount of native hCG synthesized by these cells was, however, lower than the amount of free beta subunit. (Both hCG and the beta subunit are detected by the radioimmunoassay for beta subunit, but only hCG is detected by the radioreceptor assay.) The alpha and beta subunits produced by these transformed placental cells were heterogeneous in size; the sizes of the predominant alpha and beta species, however, corresponded to those of urinary alpha and beta subunits, respectively. The seven cell lines transformed by simian virus 40 had chromosome numbers from the near diploid to the near tetraploid range. Fluorescent staining demonstrated the Y chromosome in all the transformants. Furthermore, B-type glucose-6-phosphate dehydrogenase (D-glucose-6-phosphate: NADP+ 1-oxidoreductase; EC 1.1.1.49) was present in all seven lines. These characteristics ruled out possible HeLa contamination of the transformed lines. Regulation of the synthesis of alpha and beta subunits plus hCG in these transformed human placental cells differed from the regulation in choriocarcinoma cells.

Bromodeoxyuridine↗
PubMed1978

Regulation of the synthesis of human chorionic gonadotrophin by 5-bromo-2'-deoxyuridine and dibutyryl cyclic AMP in trophoblastic and nontrophoblastic tumor cells.

Synthesis of hCG and its alpha subunit (hCG-alpha) by trophoblastic tumor cell lines (JEG-3, Reid, and BeWo) and by nontrophoblastic tumor cell lines [ChaGo and three HeLa lines (HeLa CCL2, HeLa S3, and HeLa 65)] was studied. cAMP, dibutyryl cAMP, and 8-bromo-cAMP induced, but 5-bromo-2'-deoxyuridine inhibited, the synthesis of hCG-alpha and hCG in trophoblastic tumor cells, Addition of 5-bromo-2'-deoxyuridine partially blocked the induction by dibutyryl cAMP in these cells. The synthesis of hCG-alpha and hCG in nontrophoblastic tumor cells was stimulated by dibutyryl cAMP. cAMP and 8-bromo-cAMP, however, did not affect the synthesis of hCG-alpha, although the synthesis of hCG was enhanced. 5-Bromo-2'-deoxyuridine induced hCG-alpha synthesis but did not affect hCG synthesis in nontrophoblastic tumor cells. In HeLa S3 and HeLa 65 cells, the amount of hCG-alpha and hCG produced in the presence of dibutyryl cAMP and 5-bromo-2'-deoxyuridine together was greater than the total hormone produced by each inducer separately. Our data indicate that the regulation of the production of hCG-alpha and hCG differs in trophoblastic and nontrophoblastic tumors.

Bromodeoxyuridine↗
PubMed1977

Induction of placental alkaline phosphatase in choriocarcinoma cells by 5-bromo-2'-deoxyuridine.

Growth of choriocarcinoma cells in the presence of 5-bromo-2'-deoxyuridine (BrdUrd) results in a 30- to 40-fold increase in alkaline phosphatase activity. The effects of BrdUrd is specific for phosphatase with an alkaline pH optimum. The induction by BrdUrd is probably not due to the production of an altered enzyme, since the induced enzyme resembles the basal enzyme in thermal denaturation and kinetic properties. Enzyme induction can be prevented by thymidine but not by deoxycytidine or deoxyuridine. The induction of alkaline phosphatase appears to require incorporation of the BrdUrd into cellular DNA. The presence of BrdUrd in the growth medium is not necessary for alkaline phosphatase induction in proliferating cells containing BrdUrd-substituted genomes. However, enzyme induction and maintenance of the induced levels of alkaline phosphatase in nonproliferating cells containing BrdUrd-substituted DNA requires the presence of the analogues in the medium. The induction of alkaline phosphatase by BrdUrd in probably an indirect process.

Alkaline Phosphatase↗