Toxic pollution and parasitism in freshwater fish.

As aquatic habitats throughout the world are increasingly contaminated with toxic chemicals, toxicologist strive to determine what impact these substances will have an biological systems. So far, the effects of this type of pollution on fish parasites has received little attention, despite their important status as determinants of fish health. Robert Poulin discusses the many ways in which toxic pollution may affect infections of metazoan parasites in freshwater fish.

Dose-response relationship between lymph insulin and glucose uptake reveals enhanced insulin sensitivity of peripheral tissues.

To examine the role of transcapillary insulin transport to peripheral insulin sensitivity in vivo, we performed dose-response experiments in which both plasma and thoracic duct lymph insulin and glucose utilization (Rd) were measured in conscious dogs. Euglycemic clamps (n = 22) consisted of a 3-h activation period in which insulin was infused (rates: "physiological" 3.6, 5.

Mechanism of the irreversible inactivation of mouse ornithine decarboxylase by alpha-difluoromethylornithine. Characterization of sequences at the inhibitor and coenzyme binding sites.

Mouse ornithine decarboxylase (ODC) was expressed in Escherichia coli and the purified recombinant enzyme used for determination of the binding site for pyridoxal 5'-phosphate and of the residues modified in the inactivation of the enzyme by the enzyme-activated irreversible inhibitor, alpha-difluoromethylornithine (DFMO). The pyridoxal 5'-phosphate binding lysine in mouse ODC was identified as lysine 69 of the mouse sequence by reduction of the purified holoenzyme form with NaB[3H]4 followed by digestion of the carboxymethylated protein with endoproteinase Lys-C, radioactive peptide mapping using reversed-phase high pressure liquid chromatography and gas-phase peptide sequencing. This lysine is contained in the sequence PFYAVKC, which is found in all known ODCs from eukaryotes.

Androgens and breast cancer.

We have recently demonstrated that physiological levels of androgens exert direct and potent inhibitory effects on the growth of human breast cancer ZR-75-1 cells in vivo in nude mice as well as in vitro under both basal and estrogen-stimulated conditions. The inhibitory effect of androgens has also been confirmed on the growth of dimethylbenz(a)anthracene (DMBA)-induced mammary carcinoma in the rat. Such observations are in close agreement with the clinical data showing that androgens and the androgenic compound medroxyprogesterone acetate (MPA) have beneficial effects in breast cancer in women comparable to other endocrine therapies, including tamoxifen.

Personality and socialization correlates of vicarious emotional responding.

The relations of personality and family characteristics to adults' negative vicarious emotional responses to sympathy and distress films were examined. Ss reported more sympathy and less personal distress and exhibited less skin conductance as well as heart rate deceleration when viewing a sympathy-evoking film. Dispositional emotional intensity and fantasy empathy were associated with greater self-reported emotional responding and higher skin conductance.

Group-living and the richness of the parasite fauna in Canadian freshwater fishes.

An increased transmission of ectoparasites among individual animals is considered to be an inevitable cost of living in groups, since several kinds of ectoparasites require close proximity between large numbers of hosts for successful transmission. However, we do not know whether individuals belonging to group-living species incur a greater risk of ectoparasitism than individuals of solitary species. Here, using published data from 3 families (60 species) of Canadian freshwater fishes, I test the hypothesis that group-living species are host to more species of "contagious ectoparasites" (copepods and monogeneans) than solitary host species.

An early enlargement of the putrescine pool is required for growth in L1210 mouse leukemia cells under hypoosmotic stress.

Hypoosmotic stress is a potent inducer of ornithine decarboxylase (ODC) activity in a variety of mammalian cells, but the physiological relevance of this response has not been determined. To test whether an increased putrescine content confers a growth advantage at lower osmolarities, we compared the ability of L1210 mouse leukemia cells and of ODC-overproducing variants obtained from this cell line (D-R cells) to proliferate after a hypotonic shock (325----130 mosmol/kg). The growth rate of D-R cells at 130 mosmol/kg was greater than or equal to 5-fold higher than in L1210 cells; and unlike the ODC-overproducing strain, L1210 cells underwent up to a 90% loss of viability over time as seen after restoration of normosmotic growth conditions and by trypan blue exclusion tests.

Multiple actions of synthetic 'progestins' on the growth of ZR-75-1 human breast cancer cells: an in vitro model for the simultaneous assay of androgen, progestin, estrogen, and glucocorticoid agonistic and antagonistic activities of steroids.

This study was designed to assess the multiple steroid receptor mediated activities of a series of synthetic 'progestins' on breast cancer cell growth, using the human ZR-75-1 cell line which possesses functional estrogen (ER), androgen (AR), and glucocorticoid (GR) receptors as well as progesterone (PgR) receptors. Four 17-hydroxyprogesterone derivatives (chlormadinone acetate, CMA; cyproterone acetate, CPA; medroxyprogesterone acetate, MPA; and megestrol acetate, MGA) and two 19-nortestosterone derivatives (norethindrone, NRE, and norgestrel, NRG) were thus investigated. Based on the requirement of estrogens for PgR-mediated antiproliferative effects and the reversal of PgR-mediated action by insulin, it was found that although all 'progestins' could inhibit ZR-75-1 cell growth through the PgR at low concentrations, the relative contribution of this receptor in cell growth control is highly variable between compounds.

Responses of the fish ectoparasite Salmincola edwardsii (Copepoda) to stimulation, and their implication for host-finding.

The short-lived infective copepodid stages of the copepod Salmincola edwardsii, ectoparasitic on brook trout, Salvelinus fontinalis, are under strong selective pressure to evolve efficient host-finding mechanisms. In laboratory experiments, we quantified the effects of visual and mechanical stimulation on the activity of the copepodids. We found that shadows passing above the copepodids and shock waves passing through the water generated marked increases in the rate and length of upward swimming bursts, which resulted in more time spent suspended in the water column and greater distances travelled.

Identification of a 51-kilodalton calmodulin binding protein that changes during estrogen-stimulated cell growth.

Calmodulin-binding proteins (CaMBPs) were analyzed during estrogen-stimulated growth in the human breast cancer cell line ZR-75-1. A variety of Ca2(+)-dependent and -independent CaMBPs were observed to be present in these cells. Calmodulin (CaM) binding to a 51-kilodalton protein was shown to be Ca2(+)-dependent.

Regulation of ornithine decarboxylase expression by anisosmotic shock in alpha-difluoromethylornithine-resistant L1210 cells.

Ornithine decarboxylase (ODC) activity is known to be strongly enhanced in mammalian cells by a sudden reduction in ambient osmolality. The effect of hypoosmotic shock on the regulation of ODC protein and mRNA levels was studied in a variant L1210 mouse leukemia cell line (D-R cells) which expresses ODC at greater than or equal to 100-fold higher levels than the parental cells. Hypoosmotic stress increased ODC activity in proportion with the osmotic gradient imposed to both D-R cells and their normal counterparts.

Wide spectrum of steroids serving as substrates for the formation of lipoidal derivatives in ZR-75-1 human breast cancer cells.

Recently, several natural steroids have been found to be esterified to long-chain fatty acids (FAE) in various mammalian tissues. The purpose of the present study was to determine the ability of a series of 3H-labeled steroids to serve as substrates for the formation and accumulation of such non-polar derivatives in intact cells, using the hormone-responsive ZR-75-1 human breast cancer cell line as model. All 14 steroids tested were found to be converted, directly or following further metabolism, to lipoidal ester derivatives.

Interactions between estrogens, androgens, progestins, and glucocorticoids in ZR-75-1 human breast cancer cells.

The human breast cancer cell line ZR-75-1 possesses androgen, estrogen, progesterone, and glucocorticoid receptors, thus offering a good model to study the specific role of each class of steroids in the control of breast cancer growth. Although the stimulatory action of classical estrogens (E2 and estrone) is well known, we have found a potent mitogenic effect of the adrenal estrogen androst-5-ene-3 beta,17 beta-diol (delta 5-diol) at concentrations within the range of those found in the serum of adult women, thus suggesting that delta 5-diol might be the most important estrogen in women. Androgens, on the other hand, exert a potent inhibitory effect on basal ZR-75-1 cell growth and completely reverse the stimulatory effect of estrogens on the same parameter.

Effect of S-adenosyl-1,12-diamino-3-thio-9-azadodecane, a multisubstrate adduct inhibitor of spermine synthase, on polyamine metabolism in mammalian cells.

The effects of the potent spermine synthase inhibitor S-adenosyl-1,12-diamino-3-thio-9-azadodecane (AdoDatad) on polyamine biosynthesis have been studied in transformed mouse fibroblasts (SV 3T3 cells) and in mouse leukemia cells (L1210). A dose-dependent decrease in intracellular spermine concentration was observed in both cell lines when grown in the presence of the inhibitor. A major difference in the effects seen in these two cell lines was the cytotoxicity observed in L1210 cells exposed to the inhibitor, which contrasted with little or no effects on growth of SV 3T3 cells treated similarly.

Antiestrogenic properties of keoxifene, trans-4-hydroxytamoxifen, and ICI 164384, a new steroidal antiestrogen, in ZR-75-1 human breast cancer cells.

The agonistic/antagonistic properties of two non-steroidal antiestrogens, namely trans-4-monohydroxytamoxifen (OH-TAM) and keoxifene (LY156758), and the new steroidal antiestrogen ICI164384, a 7 alpha-alkylamide derivative of estradiol (E2), were assessed by measuring their effect on the proliferation of ZR-75-1 cells, an estrogen-responsive human breast cancer cell line. While subnanomolar concentrations of both OH-TAM and LY156758 had significant estrogenic stimulatory activity on cell growth in the absence of estrogens and higher concentrations were inhibitory, ICI164384 behaved exclusively as a growth inhibitor and more potently so than the two other compounds. The three antiestrogens had similar potency to inhibit the mitogenic effect of E2 and at 300 nM, all antiproliferative effects were completely reversible by the estrogen.

Effect of 1-amino-oxy-3-aminopropane on polyamine metabolism and growth of L1210 cells.

1-Amino-oxy-3-aminopropane (AOAP) was reported to inhibit several mammalian polyamine-biosynthetic enzymes in vitro, including ornithine decarboxylase (ODC) and S-adenosylmethionine decarboxylase (AdoMetDC) [Khomutov, Hyvönen, Karvonen, Kauppinen, Paalanen, Paulin, Eloranta, Pajula, Andersson & Pösö (1985) Biochem. Biophys. Res.

Progestin inhibition of estrogen-dependent proliferation in ZR-75-1 human breast cancer cells: antagonism by insulin.

The effect of R5020 [17,21-dimethyl-19-nor-4,9-pregnadiene-3,20-dione], a synthetic progestin, was studied in the hormone-responsive ZR-75-1 human breast cancer cell line. Following a 12-day incubation with increasing concentrations of R5020, the mitogenic effect of 17 beta-estradiol (E2, 1nM) was partially (60-80%) antagonized by the progestin, with a half-maximal effective concentration measured at about 30 pM. This effect of R5020 was completely reversed by the addition of physiological concentrations of bovine insulin, as well as by the potent antiprogestin RU486 [17 beta-hydroxy-11 beta-(4-dimethylaminophenyl)-17 alpha-(1-propynyl)-4, 9-estradien-3-one], but not by the antiandrogen hydroxyflutamide (alpha, alpha, alpha-trifluoro-2-methyl-4'-nitro-m-lactotoluidide).

Down-regulation of estrogen receptors by androgens in the ZR-75-1 human breast cancer cell line.

Much clinical evidence indicates that androgens have beneficial effects in the treatment of breast cancer in women. Physiological concentrations of androgens strongly inhibit both basal and estrogen-induced cell proliferation in the human breast cancer cell line ZR-75-1 through their interaction with the androgen receptor. The present study shows that androgens strongly suppress estrogen receptor (ER) and progesterone receptor contents in this model, as measured by radioligand binding and anti-ER monoclonal antibodies.

Extensive esterification of adrenal C19-delta 5-sex steroids to long-chain fatty acids in the ZR-75-1 human breast cancer cell line.

Estrogen-sensitive human breast cancer cells (ZR-75-1) were incubated with the 3H-labeled adrenal C19-delta 5-steroids dehydroepiandrosterone (DHEA) and its fully estrogenic derivative, androst-5-ene-3 beta,17 beta-diol (delta 5-diol) for various time intervals. When fractionated by solvent partition, Sephadex LH-20 column chromatography and silica gel TLC, the labeled cell components were largely present (40-75%) in three highly nonpolar, lipoidal fractions. Mild alkaline hydrolysis of these lipoidal derivatives yielded either free 3H-labeled DHEA or delta 5-diol.

Androgen and glucocorticoid receptor-mediated inhibition of cell proliferation by medroxyprogesterone acetate in ZR-75-1 human breast cancer cells.

Medroxyprogesterone acetate (MPA) is a synthetic progestin, currently used in the adjuvant treatment of advanced breast cancer, which induces remission rates (30-40%) comparable to those obtained with other types of endocrine therapies. Since, in addition to its progestin-like action, MPA exhibits androgen- and glucocorticoid-like activities in other tissues, the present study was designed to assess the relative contribution of the different steroid receptor systems in the direct action of MPA on breast cancer cell growth, using the ZR-75-1 human mammary carcinoma cell line as an in vitro model. Unlike pure progestins, MPA potently inhibited the proliferation of ZR-75-1 cells in a concentration-dependent manner either in the presence or in the absence of estrogens, and the addition of insulin had only marginal effects on its growth-inhibitory activity.

Androgens inhibit basal and estrogen-induced cell proliferation in the ZR-75-1 human breast cancer cell line.

This study describes the inhibitory effect of 5 alpha-dihydrotestosterone (5 alpha-DHT) and its precursors testosterone (T) and androst-4-ene-3,17-dione (delta 4-DIONE) on the growth of the estrogen-sensitive human breast cancer cell line ZR-75-1. In the absence of estrogens, cell proliferation measured after a 12-day incubation period was 50-60% inhibited by maximal concentrations of 5 alpha-DHT, T, or delta 4-DIONE with half-maximal effects (IC50 values) observed at 0.10, 0.

Castration levels of plasma testosterone have potent stimulatory effects on androgen-sensitive parameters in the rat prostate.

In order to assess the biological significance of low serum androgens comparable to those which remain after castration in men treated for prostate cancer. Silastic depots continuously releasing predetermined doses of testosterone (T) have been implanted into castrated adult male rats in the absence or presence of simultaneous treatment with the pure antiandrogen Flutamide. Quite remarkably, a 3- to 5-fold increase in prostate weight (P less than or equal to 0.

Effect of transient neonatal hypothyroidism on the free aspartic acid, glutamic acid, and GABA content of different central auditory regions in the rat.

The aspartic acid, glutamic acid, and gamma-aminobutyric acid (GABA) contents were determined in four central auditory system regions in rats with transient neonatal hypothyroidism compared with control ones: the ventral and dorsal parts of the cochlear nucleus, the central nucleus of the inferior colliculus, the auditory cortex, and in an extra-auditory structure, the substantia nigra pars reticulata. The animals were sacrificed at 50 days of age, brain tissue samples were taken out by microdissection, and the free amino acids were extracted. The amino acid content was assessed by double-isotope labelling following two-dimensional thin-layer chromatography separation.