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Biomedical subjects

F L Huang

Publications and source records attributed to F L Huang.

At least 109 records · Page 6Linked to original sources
PubMed1985

Vitamin A: a key nutrient for the maintenance of epithelial differentiation.

Vitamin A deficiency or benzo(a)pyrene instillation into tracheas of Syrian golden hamsters causes squamous metaplasia of tracheobronchial epithelium, normally a mucous secretory tissue. In the present studies, we have employed a tracheal organ culture system and have reproduced the in vivo phenomenon of squamous metaplasia during culturing under vitamin A free conditions as well as after carcinogen treatment. The squamous metaplasia induced by vitamin A deficiency, both in vivo and in vitro, was accompanied by an overall increase in keratin synthesis. Vitamin A deficient tracheas were shown to contain keratins of 50, 48, 46.5 Kd detected with the antibody AE1, and 58, 56 and 52 Kd detected with AE3. These proteins were either absent or present in much less quantity in control tracheas. In deficient tracheas 60 kd keratin was found to be located specifically in squamous suprabasal cells, and 55 and 50 Kd keratin proteins were found in a greatly expanded basal cell compartment. Following carcinogen exposure, the appearance of 60 kd keratin and the enhanced expression of 50 and 55 Kd keratins preceded the squamoid metaplastic response as detected morphologically. Both the keratin changes and the morphological changes were prevented by retinoid treatment.

Animals↗
PubMed1984

Hormone-regulated expression of cellular rasH oncogene in mammary carcinomas in rats.

Differential gene expression has been observed in hormone-dependent rat mammary carcinomas during their growth and regression. A 22K MW protein, a prominent in vitro translation product of the growing as compared to the regressing tumor, was identified as the c-rasH-21,000-dalton transforming protein (p21) using a monoclonal antibody that reacts specifically with Harvey-related p21 species. The amount of p21-translated protein sharply decreased in the translation products of the regressing tumors within 6 hours post ovariectomy or dibutyryl cyclic AMP treatment. The results show that an enhanced expression of the c-rasH oncogene is associated with hormone-dependent growth of mammary carcinomas in vivo and that suppression of this oncogene precedes the tumor regression induced by either hormone withdrawal or dibutyryl cyclic AMP treatment.

Animals↗
PubMed1984

Relationship between the anticarcinogenic effect of N6,O2'-dibutyryl cyclic adenosine 3',5'-monophosphate and modulation of gene expression and inhibition of binding of 7,12-dimethylbenz(alpha)anthracene to DNA of mammary cells.

Carcinogenic doses of 7,12-dimethylbenz(alpha)anthracene (DMBA) failed to induce mammary carcinoma in the rats that have received N6,O2'-dibutyryl cyclic adenosine 3',5'-monophosphate (DBcAMP) (Cancer Res., 43: 2736, 1983). We now report that the anticarcinogenic effect of DBcAMP correlates with its effect on DNA binding of the carcinogen and on gene expression. Cultured mammary epithelial cells in exponential phase of growth were used to determine the effect of DBcAMP on DMBA binding to DNA. DBcAMP inhibited the DMBA binding in carcinogen-susceptible mammary cells of 50-day-old rats, but it had no effect on the binding in the DMBA-resistant mammary cells of 35- and 110-day-old rats. The inhibitory effect of DBcAMP was appreciable at the concentration of 10(-7) M, one tenth the concentration of [3H]DMBA. DBcAMP at 10(-6) M concentration exhibited the maximal inhibition of DMBA binding; i.e., binding in DMBA-susceptible mammary cells was reduced to the level of binding observed in DMBA-resistant mammary cells. Polyadenylate-containing RNAs isolated from mammary glands of DMBA-susceptible rats (50-day-old) yielded translation products in vitro which bear a greater resemblance to translation products of growing DMBA-induced tumors than they do to products of messenger RNAs from regressing tumors or DMBA-resistant mammary glands of 110-day-old rats. DBcAMP administered to the susceptible rats resulted in changes in the translation products of the mammary glands; the translation products of the glands became similar to those of DMBA-resistant mammary glands or regressing tumors. DMBA feeding 1 day after DBcAMP treatment could not reverse this effect of DBcAMP. These data suggest that the role of cyclic adenosine 3',5'-monophosphate at the genomic level is responsible for the anticarcinogenesis of mammary cells.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1983

High-pressure liquid chromatographic separation of a mixture of corticosteroids, androgens, and progestins.

Fifteen steroids including corticosteroids, androgens, progestins, and their derivatives were completely separated by reverse-phase high-pressure liquid chromatography on a ChemcoPak 7 ODS-H column in 50 min. The elution procedures were first with water:methanol:acetonitrile:isopropanol 55:32:6.5:7.5 (v/v) for 15 min and followed with a linear gradient elution for 35 min from 0 to 80% of water:methanol:n-butanol 40:40:20 (v/v). The applicability of this method was successfully demonstrated in the analyses of the biological samples of carp plasma, testis, and head kidney.

Adrenal Cortex Hormones↗
PubMed1983

Alteration in gene expression at the onset of hormone-dependent mammary tumor regression.

Two hormone-dependent mammary carcinomas regressing after hormone removal, [one primary 7,12-dimethylbenz(alpha)-anthracene induced, and the other transplanted MTW9] were used as models to test the hypothesis that the regression of hormone-dependent mammary tumors is triggered by a modification of the genetic expression. In support of the hypothesis, we observed that: (1) the in vitro translation products of poly(A)+ RNAs differ between growing and regressing tumors; (b) the difference is localized in four protein bands (mr 53,000, 35,000, 22,000 and 20,000) of the electrophoretic pattern that decrease in their concentrations and one protein band (Mr 20,500) that increases during regression; (c) the changes in the translation products occur within 6 hr post-hormone removal, and the changes are reversed when resumption of tumor growth was induced by replenishment of the hormone to the host rats: and (d) three autonomously growing tumors exhibit a unique translation pattern which differs from that of hormone-dependent tumors, and the pattern does not change upon hormone removal. The results suggest that hormonal regulation of mammary tumor growth is related to specific genetic transcripts, and loss of hormone dependence of growth may correlate with the changes in this genetic control.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1981

Separation of subunits of pike eel gonadotropin by hydrophobic interaction chromatography.

Subunits of pike eel gonadotropin were dissociated in propionic acid and separated by hydrophobic interaction chromatography on phenyl-Sepharose CL-4B with a high yield (79%). Isolated subunits were homogeneous, as tested by sodium dodecyl sulphate disc electrophoresis and by N-terminal analysis. The biological activities of two subunits, S-I and S-II, were 0% and 2.8% of native molecule, respectively, as assayed by stimulation of androgen production on carp testes. Reassociated molecules restored about 75% activity.

Animals↗
PubMed1981

Isolation and characterization of gonadotropin isohormones from the pituitary gland of pike eel (Muraenesox cinereus).

Pike eel gonadotropins were isolated from pituitary glands by 40% alcohol-6% ammonium acetate, pH 5.1 extraction and were purified by DEAE-cellulose chromatography and electrophoresis into four electrophoretically homogeneous forms. These four isohormones were biologically identified as gonadotropins by the stimulation of 32 P-uptake in 1 day-old chick testes, by the induction of ovulation in catfish, and by the in vitro production of testosterone from isolated rat Leydig cells and of androgen from carp testes. The amino acid composition of the isohormones were similar to other known piscine gonadotropins (carp and salmon) and were composed of two non-identical subunits with Tyr and Ser as N-terminal amino acid residues. The molecular weights of two subunits were 15000 and 10500, respectively, as estimated by SDS-gel disc electrophoresis.

Amino Acids↗
PubMed1978

Control of rat skeletal-muscle phosphorylase phosphatase activity by adrenaline.

Administration of adrenaline to an isolated rat hindlimb preparation rapidly decreased muscle phosphorylase phosphatase (EC 3.1.3.17) activity and increased heat-stable and trypsin-labile phosphatase inhibitor activity. This was associated with increased tissue cyclic AMP concentrations, phosphorylase (EC 2.4.1.1) activation and glycogen synthase (EC 2.4.1.11) inactivation.

Animals↗
PubMed1977

Tissue culture of lens epithelial cells from normal and Nakano mice.

Lens epithelial cells from normal and Nakano adult mice have been cultured for over 1 year, and the cells have retained certain differentiated characteristics. Fluorescent antibody to mouse gamma crystallin reacted with the spherical lentoid bodies which appeared approximately 2 weeks after the start of the culture. The lentoid bodies also contained cells which had few cell organelles and homogenous cytoplasms. Both gamma crystallin production and loss of cellular organelles are characteristics of differentiated fiber cells rather than epithelial cells. An inhibitor of the Na-K ATPase is responsible for the hydration and subsequent cataract formation in the Nakamo mouse. The inhibitor of the Na-K ATPase was demonstrated in the lens in culture from the Nakamo mice, but no inhibitory activity was detected in the cultures from normal mice.

Adenosine Triphosphatases↗