Saintpaulia (African violet) leaves are known to be damaged by a rapid temperature decrease when cold water is applied to the leaf surface; the injury is ascribed to the chloroplast damage caused by the cytosolic pH decrease following the degradation of the vacuolar membrane in the palisade cells. In this report, we present evidence for the involvement of Ca(2+) in facilitating the collapse of the vacuolar membrane and in turn in the temperature sensitivity of Saintpaulia leaves. In the presence of a Ca(2+) chelator (EGTA) or certain Ca(2+) channel inhibitors (Gd(3+) or La(3+)) but not others (verapamil or nifedipine), the pH of the vacuole, monitored through BCECF (2',7'-bis(carboxyethyl)-4 or 5-carboxyfluorescein) fluorescence, did not increase in response to a rapid temperature drop.
View Article and Find Full Text PDFIt is well known that saintpaulia leaf is damaged by the rapid temperature decrease when cold water is irrigated onto the leaf surface. We investigated this temperature sensitivity and the mechanisms of leaf damage in saintpaulia (Saintpaulia sp. cv.
View Article and Find Full Text PDFThe inhibition of estrogen biosynthesis by the use of aromatase inhibitors is emerging as a valuable approach to breast cancer therapy. Because smoking has a profound effect on estrogen-related processes we examined the ability of tobacco constituents to suppress estrogen production by breast cancer aromatase. N-n-octanoylnornicotine and N-(4-hydroxyundecanoyl) anabasine suppressed aromatase activity in culture of two human breast cancer cell lines, MDA-MB-231 (IC50 of 310 and 20 microM, respectively) and SK-BR-3 (IC50 of 450 and approximately 2 microM, respectively).
View Article and Find Full Text PDFBiochim Biophys Acta
May 1993
Mutant aromatase cytochrome P-450s, expressed in CHO cells after transfection with cDNAs, have been characterized in terms of their catalytic efficiencies. After solubilization from microsomes, specific aromatase P-450 content of wild-type and mutants Pro308Phe, Asp309Asn, Asp309Ala and Phe406Arg was quantitated by a sandwich enzyme-linked immunosorbent assay (ELISA). Microsomal aromatase activity was determined by the 3H-water method using [1 beta-3H]androstenedione as substrate.
View Article and Find Full Text PDFSite-directed mutagenesis experiments have been carried out to determine the structure-function relationship of human aromatase. By sequence comparison, the region in aromatase that corresponds to the distal helix of cytochrome P-450cam has been identified to be Gln-298 to Val-313. Eight aromatase mutants with changes in this region, i.
View Article and Find Full Text PDFJ Steroid Biochem Mol Biol
December 1992
Mutant forms of aromatase cytochrome P-450 bearing modifications of amino acid residues Pro308 and Asp309 and expressed in transfected Chinese hamster ovary cells were subjected to kinetic analysis and inhibition studies. The Km for androstenedione for expressed wild type (11.0 +/- 0.
View Article and Find Full Text PDFMurine hybridoma-derived monoclonal antibody (MCA) to Dunning rat prostate adenocarcinoma R-3327HIS (androgen independent type) has been produced by fusing P3x63 Ag8-653 myeloma cells with splenocytes of BALB/c mice which were immunized with R-3327HIS tumor cell membranes. One monoclonal antibody designated MCA-R1 (IgG2a subtype) produced an intense immunostaining of various androgen independent Dunning rat prostate tumor sublines (HIS, HIM, HIF, AT-1, AT-2, AT-3, MAT-Lu and MAY-Ly-Lu), but did not stain other tumors of rat origin or normal rat tissues. Marginal immunostaining was detected in the androgen responsive R-3327H and R-3327G tumor subline.
View Article and Find Full Text PDFHinyokika Kiyo
January 1988
The response of androgen-sensitive Noble (Nb) rat prostatic adenocarcinoma [2Pr-121D (1)] to varying doses (50 approximately 1,000 micrograms/kg body weight) of diethylstilbestrol (DES) was investigated and characterized with respect to cytosol and nuclear androgen binding profiles, histology and pattern of relapse. Inhibition of tumor growth was closely related to the dose of DES. Treatment at all but the lowest dose (50 micrograms/kg) initially caused tumor regression, whereas serum testosterone concentrations in all groups, including that receiving the lowest dose, were decreased to castrate levels.
View Article and Find Full Text PDFCancer Immunol Immunother
November 1987
A new spontaneously arisen murine breast tumor, designated JC, has been established in immunocompetent BALB/c mice. Upon reestablishment of tumor in vitro and in vivo, the epithelial murine tumor cells retained their original papillary adenocarcinoma morphology. Various immunotherapy protocols have been performed in previously implanted and progressively growing JC tumor in syngeneic hosts with a murine monoclonal antibody (McAb), F36/22 (IgG3).
View Article and Find Full Text PDFMechanically isolated epithelium and stroma from benign hypertrophic prostates were highly pure on the basis of histochemical and biochemical criteria. By electrophoretic analyses, whole cellular and nuclear proteins were compared among whole tissues, epithelium, and stroma. The characteristic protein profiles of benign hypertrophic prostates were reflected in the electrophoretic patterns of the stroma.
View Article and Find Full Text PDFThe effect of 4-methyl-4-aza-steroidal inhibitors of 5 alpha-reductase has been evaluated on tumor growth in the Noble rat model of prostatic adenocarcinoma. The growth characteristics of the tumor line 2Pr-121D(1) were consistent with heterogeneity of cell types, composed of androgen-sensitive and androgen-insensitive malignant cells. Both sodium 4-methyl-3-oxo-4-aza-5 alpha-pregnane-20 (s)-carboxylate and 17 beta-N,N-diethylcarbamoyl-4-methyl-4-aza-5 and 17 beta-N,N-diethylcarbamoyl-4-methyl-4-aza-5 alpha-androstan-3-one significantly retarded tumor progression.
View Article and Find Full Text PDFThe effect of sodium 4-methyl-3-oxo-4-aza-5 alpha-pregnane-20(s)-carboxylate (4-MAPC) on testosterone metabolism was investigated in rat and human prostates in organ culture. The general properties of the test system for androgen metabolism and response to inhibitors were in close agreement with in vivo observations. As an inhibitor of prostatic tumor 5 alpha-reductase, 4-MAPC was equally as effective as 17 beta-N,N-diethylcarbamoyl-4-methyl-4-aza-5 alpha-androstan-3-one, reported to be a potent 5 alpha-reductase inhibitor.
View Article and Find Full Text PDFThe studied 6-methylene-4-androsten-3-ones proved to be significantly inferior to 6-methylene-4-pregnene-3,20-dione and its 17-acetoxy derivative described in Part 1 as inhibitors of 4-ene-3-ketosteroid 5 alpha-reductase [1] in vitro. Surprisingly, the 6-methylene derivative of testosterone was only weakly active until acetylated, when an effective inhibitor was obtained. Etherification of the hydroxyl-group, its replacement by a hydrocarbon chain, or introduction of a substituent at C17 or on the methylene group led to virtual loss of activity.
View Article and Find Full Text PDFUsing a short-term organ culture assay, some 6-methylene derivatives of progesterone and testosterone have been evaluated for their effects on testosterone metabolism in rat and human prostatic tissues, and on DNA synthesis in explants from 7-day castrated rats. Comparative studies showed that the ability to inhibit 5 alpha-reductase activity was fairly specific with respect to structural requirements. Methylene substitution at the C6 position of the progesterone molecule was associated with high inhibitory activity.
View Article and Find Full Text PDFThe mechanism by which estrogens inhibit castration atrophy has been investigated morphologically and biochemically utilizing ventral prostate from Copenhagen rats. The suppression of weight loss and gross edematous appearance of the prostate associated with the in vivo effect of 17 beta-estradiol (E2) could not be accounted for by DNA and protein synthesis. Increase in the fluid content in the tissues was confirmed by demonstration of significant increase in the ratio of wet/dry tissue weights.
View Article and Find Full Text PDFEstramustine phosphate, a drug effective in a substantial number of patients with cancer of the prostate who had failed on other forms of therapy, has been shown to be split into its constituents, that is estradiol-17beta and the carbamate nitrogen mustard by non-cancerous and cancerous human prostatic tissues. This fact may explain, in part, the mechanism of action and efficacy of the drug in patients with cancer of the prostate. In addition to presenting results on the hydrolysis and its products accomplished by human prostatic tissues we discuss the limitations of extrapolating animal results with estramustine phosphate to the human condition and possible parameters that bear upon the insignificant toxic and estrogenic effects observed in patients given estramustine phosphate.
View Article and Find Full Text PDFCancer Treat Rep
August 1977
We have previously reported on test systems, based on 5alpha-reductase (5alpha-RA) and arginase activities and steroid deposition in animal prostates, potentially useful in screening drugs possibly effective in cancer of the prostate. Recently, we have concentrated on the development of other in vivo and in vitro systems which may prove of further value in testing such drugs. These systems include the following: (a) The effects of drugs on 5alpha-RA activity in human and animal non-malignant and human cancerous prostatic tissues in organ culture.
View Article and Find Full Text PDFShort-term organ culture of rat and human prostatic tissues has been utilized as a means of testing drlgs potentially useful in cancer of the prostate. Optimal conditions, particularly the concentration of T, have been established for organ culture of such tissues and the effects of various drugs on 5alpha-reductase activity (5alpha-RA) have been utilized as a means of ascertaining antiprostatic actions of the various compounds and drugs tested. Thus, it was shown that estracyt, estradiol-17beta, progesterone, and novel steroids and steroid-conjugates have definite effects on 5alpha-RA in this system.
View Article and Find Full Text PDF