Developmental defects of the ventromedial hypothalamic nucleus and pituitary gonadotroph in the Ftz-F1 disrupted mice

Ad4BP (or SF-1) has been identified as a transcription factor which regulates all the steroidogenic P450 genes in the peripheral organs, and is encoded by the mammalian homologue of Drosophila FTZ-F1 gene. mRNA coding for Ad4BP was detected in the hypothalamus and pituitary of rats by RT-PCR. Immunohistochemical analyses using an antiserum to Ad4BP in the brain and pituitary revealed that the transcription factor is expressed in nuclei of the dorsomedial part of the ventromedial hypothalamus (dmVMH) and in some subpopulation of the adenohypophysial cells. Double immunostaining of the pituitary for Ad4BP and trophic peptide hormones, FSH, TSH, and ACTH, indicated a restricted localization of Ad4BP to the gonadotroph. Disruption of the mouse Ftz-F1 gene was clarified to induce severe defects in the organization of the dmVMH and the function of the pituitary gonadotroph. However, some of the dm VMH neurons and pituitary gonadotrophs persisted, which provided a sharp contrast to complete agenesis of the peripheral steroidogenic tissues (adrenal and gonads) in the mutant mouse. Additional abnormalities were seen in the ventrolateral part of VMH and dorsomedial hypothalamic nucleus, both of which do not express Ad4BP but have strong reciprocal fiber-connections with the dmVMH. Aromatase P450-containing cells in the medial preoptico-amygdaloid region, which were devoid of Ad4BP, persisted even in the brain of the gene disrupted mice. The present results clearly showed that the hypothalamic and pituitary Ad4BPs are essential to normal development of the functional VMH and gonadotroph through some mechanism distinct from that in the peripheral steroidogenic tissues.

Irradiation induces WAF1 expression through a p53-independent pathway in KG-1 cells

WAF1 binds to cyclin-Cdk complexes and inhibits their activity, causing cell cycle arrest. Previous studies have shown that expression of WAF1 is induced through the p53-dependent pathway; WAF1 is induced in cells with functional p53 but not in cells with either mutant p53 or no 53. Human myeloblastic leukemia cells KG-1 had no constitutive expression of p53, and irradiation did not induce p53. However, irradiation increased WAF1 expression in KG-1 cells and other cell lines containing mutant p53. The KG-1 cells constitutively produced low levels of tumor necrosis factor (TNF); irradiation markedly increased the production of TNF. Notably, induction of WAF1 mRNA by irradiation was blocked by anti-TNF antibody. Furthermore, exogenously added TNF increased levels of WAF1 mRNA in these cells. Irradiation increased the rate of WAF1 transcription 3-fold, and the half-life (t1/2) of WAF1 mRNA in these cells increased from < 1 h in unirradiated cells to > 4 h in irradiated cells. These findings indicate that increased levels of WAF1 transcripts occur, at least in part, through a pathway of TNF production and that the increase in WAF1 mRNA observed after irradiation is regulated by both transcriptional and posttranscriptional mechanisms. Our present study strongly suggests that an alternative pathway of induction of WAF1 occurs independent of activation by p53.

Presence of estrogen receptors in aromatase-immunoreactive neurons in the mouse brain

The present study was undertaken to demonstrate estrogen receptors in aromatase-immunoreactive neurons showed the immunoreactivity for estrogen receptors in the cell nuclei in the medial subdivision of the bed nucleus of the stria terminalis and the posterodorsal division of the medial amygdaloid nucleus, but a few did in the medial preoptic area. These results suggest that aromatase-immunoreactive neurons in the former two areas are regulated by steroids through estrogen receptors in their cell nuclei.

Irradiation increases manganese superoxide dismutase mRNA levels in human fibroblasts. Possible mechanisms for its accumulation

Irradiation induces the production of superoxide radicals (O2.-), which play an important causative role in radiation damage. Manganese superoxide dismutase (MnSOD) is a mitochondrial enzyme involved in scavenging O2..-. This study examined MnSOD gene regulation by irradiation in WI38 human fibroblasts. Unstimulated fibroblasts constitutively expressed MnSOD activity and mRNA; irradiation markedly increased MnSOD activity and mRNA levels. The increase in MnSOD transcripts by irradiation was both time- and dose-dependent. WI38 fibroblasts constitutively produce low levels of interleukin-1 (IL-1). The induction of MnSOD mRNA by irradiation was partially blocked by anti-IL-1 antibodies, and treatment of cells with IL-1 also increased MnSOD mRNA levels. Inhibition of the cyclo-oxygenase pathway with indomethacin augmented the induction MnSOD mRNA by irradiation and prostaglandin E2 inhibited the accumulation of MnSOD mRNA by irradiation. Transcriptional run-on analysis showed that irradiation increased the rate of MnSOD transcription 2-fold. Stability studies of MnSOD mRNA in these cells showed that the half-life increased from < 1.5 h in unirradiated cells to > 4 h in irradiated cells. These results suggest that induction of the MnSOD gene after irradiation is regulated, at least in part, by IL-1 production and that increased levels of MnSOD transcripts also occur through a pathway of endogenous prostaglandin E2 production. Our data indicate that the increase in MnSOD mRNA observed after irradiation occurs through both transcriptional and post-transcriptional mechanisms.

Neurofilament-associated protein phosphatase 2A: its possible role in preserving neurofilaments in filamentous states

Neurofilament phosphatase (NF-phosphatase) activity, which dephosphorylates NF proteins phosphorylated by cyclic AMP-dependent protein kinase (A-kinase), was detected in NF fractions prepared from bovine spinal cords. This phosphatase was suggested to be associated with NFs by gel filtration and sedimentation analysis and was further demonstrated by dephosphorylation-dependent binding assay of NFs to microtubules. The NF-associated NF-phosphatase was identified as a type of protein phosphatase 2A (PP2A) by (i) its complete inhibition with 100 nM okadaic acid, at which concentration the purified type 1 protein phosphatase (PP1) was inhibited only 25%; (ii) the absence of effect of inhibitor-2, a specific inhibitor of PP1, on the NF-phosphatase activity; and (iii) the detection of 38-kDa catalytic and 65-kDa regulatory subunits of PP2A by immunoblotting. The NF-associated PP2A was partially solubilized from NFs by a high concentration of MgSO4, and the solubilized PP2A was suggested by gel filtration to be a dimeric holoenzyme consisting of a 38-kDa catalytic and a 65-kDa regulatory subunit. Phosphorylated NF-L, which is assembly incompetent, was induced to assemble into filaments by dephosphorylation with PP2A. These results suggest a role of NF-associated PP2A in preserving filamentous forms of NF in neurons.

cDNA cloning of BR gamma, a novel brain-specific isoform of the B regulatory subunit of type-2A protein phosphatase

A cDNA clone for a novel isoform of the B regulatory subunit of type 2A protein phosphatase (BR) was isolated from a rat brain cDNA library by hybridization under low-stringency conditions with the BR beta cDNA fragment as a probe. The novel cDNA encodes a protein of 447 amino acids. The identities of amino acid sequences of the novel isoform with those of rat BR alpha and BR beta were 80% and 85%, respectively, with a unique sequence at the C-terminal. Since this isoform is thought to be encoded by a third gene for the B regulatory subunit, it was named BR gamma. The mRNA for BR gamma was 4.2 kb. The expression level of BR gamma was high in the brain and spinal cord of rats, and its expression was also detected in mouse and human brains, but in contrast to BR beta, it was not detected in the testes of rats or mice. Thus BR gamma is though to be a brain-specific isoform of the B regulatory subunit.

Portal vein reconstruction using an internal jugular vein as a graft: report of a case

We report the case of a 41-year-old man with pancreatic carcinoma invading the portal vein who was successfully treated by portal vein resection combined with pancreatoduodenectomy and reconstruction using an autointernal jugular vein. The internal jugular vein is an ideal graft for portal vein replacement because it has sufficient length, a well-matched diameter, and there is no venous insufficiency after unilateral resection. Nevertheless, this is the first report of portal vein reconstruction using the internal jugular vein as a graft.

Report on the first annual survey of home parenteral nutrition in Japan

An annual survey of the current national status of home parenteral nutrition (HPN) in Japan was begun in 1991, with a total of 231 registered patients from 142 institutions providing adequate data for evaluation and analysis. HPN was given for an average of 683 +/- 764 days to 93 patients with malignant diseases and 138 with benign disease, including 53 with inflammatory bowel disease and 79 with short bowel syndrome, 107 (46.3%) of whom were successfully rehabilitated. By the end of 1990, 61% of the patients investigated were still on HPN, 7% had already completed HPN, and 26% had died, the deceased accounting for 54% of the patients with malignant diseases and 7% of those with benign diseases. A total of 321 catheters had been used by all 231 patients, the most common being the subcutaneously implanted type, accounting for 33% of all catheters. By the end of 1990, 32% of these 321 catheters were still in place, 18% had been removed on the termination of HPN and 44% had been removed due to complications of total parenteral nutrition, including 20% for catheter fever. Rehospitalization was required in 62% of the patients, the cause being HPN-related in 21% of the total patients. Metabolic complications were experienced by 60% of the patients, but none of these were severe although 6% required hospitalization.(ABSTRACT TRUNCATED AT 250 WORDS)

Inhibition of aromatase activity in human placental microsomes by 13-retro-antiprogestins

Mifepristone (RU 486), used clinically for the termination of early pregnancy, and its acetyl and 13-retro (13 alpha) analogs show potent antiproliferative effects against estrogen-dependent human breast tumors and endometriosis. However, there has been no report on direct inhibition of aromatase by antiprogesterones. Aromatase inhibitors have been shown to be effective against estrogen-dependent breast cancer. We evaluated the inhibition of aromatase by various antiprogestins (ZK 112.993, ZK 98.734, ZK 114.043, ZK 98.299, and ZK 114.863). Human placental microsomes were incubated with [1 beta-3H,4-14C] androstenedione (3-114 nM) in the presence of NADPH, with or without putative inhibitors (10-200 microM). Aromatase activity was assessed by tritium release to water from the 1 beta-position of the substrate. ZK 112.993 and ZK 98.734 did not show any inhibitory effect. The statistical analysis of the data using standard errors was obtained from replicate experiments. ZK 114.043 showed slight inhibition with a Ki of 54.8 +/- 6.4 microM (m +/- SE, n = 6) against androstenedione aromatization. The two 13-retro-steroids, ZK 98.299 and ZK 114.863, showed aromatase inhibition with Ki values of 19.0 +/- 1.5 microM (n = 7) and 12.7 +/- 0.94 microM (n = 7), respectively, which is weak with respect to some known potent inhibitors, but significant when compared with the other antiprogestins which were tested. The results suggest that the unnatural 13-retro-antiprogestin conformation may have a better fit to the aromatase active site than the natural 13 beta-antiprogestin conformation. (Steroids 60:234-238, 1995).

Characterization of the inactivation of nitric oxide synthase by NG-methyl-L-arginine: evidence for heme loss

The nitric oxide synthases (NOS) are a unique family of P450-type hemoproteins that catalyze the formation of .NO and citrulline from L-arginine, oxygen, and NADPH. NG-Methyl-L-arginine (L-NMA) has been shown to function as a slow, partially uncoupled alternate substrate and mechanism-based inhibitor of the inducible NOS [Olken, N. M., & Marletta, M. A. (1993) Biochemistry 32, 9677-9685]. In this report, the inactivation of NOS by L-NMA has been investigated in detail. Inactivation fails to occur under an argon atmosphere, establishing turnover dependence. The partition ratio, defined as the number of molecules of citrulline formed per NOS monomer inactivated, is 108 +/- 3. By utilizing NG-methyl-L-[2,3-3H2]arginine and NG-[14C]methyl-L-arginine, the stoichiometry of radiolabeling is 0.11 +/- 0.01 equiv of tritium and 0.41 +/- 0.10 equiv of carbon-14 per inactivated NOS monomer. Dialysis under native conditions does not change this stoichiometry. However, dialysis of NOS following denaturation decreases the stoichiometry of radiolabeling to 0.08 +/- 0.04 equiv of tritium and 0.12 +/- 0.04 equiv of carbon-14 per inactivated NOS monomer. Absolute and CO-reduced difference spectroscopy indicates that inactivation of L-NMA is accompanied by a substantial loss of the heme chromophore, which is not prevented by catalase. HPLC analysis of NOS heme following inactivation with L-NMA indicates substantial loss of heme. These findings suggest that multiple mechanisms may contribute to the loss of NOS activity by L-NMA, including heme loss and possibly protein and cofactor modification.

Inactivation of horseradish peroxidase by 3,5-dicarbethoxy-2,6-dimethyl-4-ethyl-1,4-dihydropyridine

In the presence of H2O2, horseradish peroxidase (HRP) catalyzes the one-electron oxidation of a porphyrinogenic agent, 3,5-dicarbethoxy-2,6-dimethyl-4-ethyl-1,4-dihydropyridine (DDEP), leading to formation of an ethyl radical, inactivation of the enzyme, and formation of an altered heme product. The loss of heme during the inactivation of HRP was dependent on the duration of exposure to DDEP as well as the concentration of H2O2 and DDEP. The pseudo first order rate constant for the oxidation of DDEP by compound I of HRP at pH 7.4 was 0.07 min-1, and the maximal extent of heme loss was 35%. The altered heme product, which was isolated by reverse phase HPLC, was characterized by the use of mass and 1H NMR spectrometry as a substitution product of a C2H4OH moiety for a meso proton of the prosthetic heme [meso-(hydroxyethyl)heme]. The source of the oxygen in the C2H4OH moiety appeared not to be H2O2 or H2O as 18O was not incorporated in the heme adduct when H2(18)O2 or H2(18)O was used. The DDEP-mediated reaction did not form the expected delta-meso-ethylheme adduct analogous to the ethyl radical-mediated inactivation of HRP by ethylhydrazine (EH) [Ator et al. (1987) J. Biol. Chem. 262, 14954-14960]. However, we have found that meso-(hydroxyethyl)heme was formed in the EH-mediated reaction, albeit in apparently lower amounts than delta-meso-ethylheme. Perhaps the proximity of the heme to the ethyl radical may play a role in determining the nature of the heme products formed.

Immunocytochemical localization of aromatase in the ovary of superovulated cattle, pigs and sheep

The localization of aromatase, an enzyme converting androgens to estrogen, in the ovaries of superovulated cattle, pigs and sheep was studied immunocytochemically in the preovulatory and postovulatory period using anti-human placental aromatase cytochrome P-450 antiserum. Immunostaining for aromatase was detected in the granulosa cells of preovulatory follicles of all species studied. Theca interna cells were stained in preovulatory follicles in the pig but not in cattle and sheep. Interstitial gland cells, cumulus cells and oocytes were unstained in all species. In cattle and pig the corpora lutea were unstained whereas they displayed staining in the sheep. Preantral and small antral follicles were unstained during both the preovulatory and postovulatory period in all species. It is concluded that granulosa cells of preovulatory follicles are the main residence for aromatase activity in superovulated cattle, pig and sheep, whereas the activity of theca interna and corpora lutea is species specific.

Immunocytochemical localization of aromatase-containing neurons in the rat brain during pre- and postnatal development

The present immunohistochemical study demonstrates the ontogenetic appearance of aromatase-immunoreactive neurons in several discrete regions of the hypothalamus and limbic system in the rat brain, using a purified antibody against human placental aromatase cytochrome P450. Immunoreactive cells were first detected in the preoptic area on the 13th day of embryonic life (E13), and additionally in the bed nucleus of the stria terminalis on E15. Labeled cells were also found in the medial amygdaloid nucleus and the ventromedial nucleus on E16, and some were detected in the arcuate nucleus on E19. As gestation progressed, the number and the immunoreactivity of these cells gradually increased and peaked within definite periods of perinatal life and thereafter declined or disappeared. The immunoreactive cells were also found in the central amygdaloid nucleus and the lateral septal nucleus, and in the ventral pallidum, after the 14th day of postnatal life (P14) and 30th day (P30), respectively. The distribution of aromatase-immunoreactive neurons was similar between the sexes, while the immunoreactivity was higher in males than in females after late gestational days. No immunoreaction was detectable in other regions of the telencephalon or midbrain at any time periods studied. The aromatase-immunoreactive neurons in the specific regions may be involved in the sexual differentiation of the brain.

pH-dependent one- and two-electron oxidation of 3,5-dicarbethoxy-2,6-dimethyl-4-ethyl-1,4-dihydropyridine catalyzed by horseradish peroxidase

The porphyrinogenic agent 3,5-dicarbethoxy-2,6-dimethyl-4-ethyl-1,4-dihydropyridine (DDEP) is known to inactivate hepatic cytochrome P450 (P450) enzymes 2C11, 2C6, and 3A1 [Correia et al. (1987) Arch. Biochem. Biophys. 258, 436-451] by different mechanisms. The inactivation of P450 2C11 and 2C6 appears to be due to the ethylation of the heme in the active sites of the enzymes [Augusto et al. (1982) J. Biol. Chem. 257, 11288-11295], whereas the inactivation of P450 3A1 appears to involve the covalent binding of the heme to the apoprotein [Correia et al. (1987)]. Moreover, we have found that DDEP inactivates horseradish peroxidase (HRP) pretreated with hydrogen peroxide. In this system, DDEP was oxidized predominately to 3,5-dicarbethoxy-2,6-dimethyl-4-ethylpyridine (EDP) under weakly acidic conditions and predominately to 3,5-dicarbethoxy-2,6-dimethylpyridine (DP) under basic conditions. The loss of heme and the formation of altered heme products were also pH-dependent and were correlated with the formation of DP and the inactivation of HRP. Thus the inactivation of HRP appears to depend on the formation of an ethyl radical, which presumably reacts with the heme in the active site of the enzyme. Similar product ratios were obtained for the oxidation of DDEP by K3Fe(CN)6, indicating that product ratios of DP over EDP are mainly determined by the pH of buffer. These results, in addition to semiemperical calculations (AM1) for the oxidation of DDEP in the gas phase, are consistent with the idea that the inhibitor undergoes a single-electron oxidation to form the DDEP radical cation, the fate of which depends on the environment of the active site of the enzyme. The proposed formation of a radical cation by the abstraction of an electron from nitrogen is consistent with the finding of low intramolecular isotope effects of the metabolism of 3,5-dicarbethoxy-2,6-dimethyl-[4-2H,4-1H]-1,4-dihydropyridine by P450 2C11 and 3A4. Under basic or aprotic conditions, the radical dissociates to form DP and the ethyl radical, which reacts with the heme, thereby inactivating the enzyme. Under acidic or polar conditions, the radical undergoes an additional one-electron oxidation to form EDP.(ABSTRACT TRUNCATED AT 400 WORDS)

Immunolocalization of steroidogenic enzymes P450scc, 3 beta HSD, P450c17 and P450arom in the corpus luteum of the Hokkaido brown bear (Ursus arctos yesoensis) in relation to delayed implantation

The objective was the immunocytochemical localization of steroidogenic enzymes in the corpus luteum of Hokkaido brown bears during the period of delayed implantation. Cholesterol side-chain cleavage cytochrome P450 (P450scc), 3 beta-hydroxysteroid dehydrogenase (3 beta HSD), 17 alpha-hydroxylase cytochrome P450 (P450c17) and aromatase cytochrome P450 (P450arom) were localized as biosynthetic sites of pregnenolone, progesterone, androgens, and oestrogens, respectively. Ovaries containing corpora lutea were obtained from three mature bears during the expected delayed implantation period and ovarian sections were immunostained by the avidin-biotin-peroxidase complex method using polyclonal antibodies generated against steroidogenic enzymes of mammalian origin. P450scc and 3 beta HSD were localized in all luteal cells, whereas P450c17 (0.4-5.1% of 1000 cells) and P450arom (7.1-11.2% of 1000 cells) were localized in only a few luteal cells. These data suggest that luteal cells contain steroidogenic enzymes required for progesterone synthesis but also have a minimum capability for synthesizing androgen and oestrogen during the delayed implantation period in Hokkaido brown bears.

Steroidogenic activity of atretic follicles in the cycling hamster ovary and relation to ultrastructural observations

To evaluate the relation between the steroidogenic activity and cell proliferation of individual follicles in mature hamster ovaries during the estrous cycle, the localization of enzymes involved in estrogen biosynthesis and bromodeoxyuridine (BrdU) incorporation were examined immunohistochemically. Moreover, granulosa cells from the early atretic follicle were examined by scanning and transmission electron microscopy. Immunoreactivity for aromatase was localized in the granulosa cells of healthy developing follicles and Graafian follicles, as well as in newly formed granulosa lutein cells. In the healthy follicles of an ovulation cycle, intensity of aromatase immunoreactivity was suddenly decreased on day 3. The theca interna cells of healthy developing follicles were immunopositive for 17 alpha-hydroxylase/C17-C20 lyase (17 alpha-lyase) from day 2 to the morning of day 4, but on the evening of day 4 most theca interna cells were immunonegative except for only a few cells of the large Graafian follicles. BrdU incorporation was observed in the granulosa cells of healthy developing follicles, in the endothelial cells of capillaries around the developing follicles, and of newly formed corpora lutea. Very early morphological signs of atresia was the pyknotic change of a few granulosa cells lining the antral cavity. In that follicle, the number of BrdU-incorporating granulosa cells was suddenly decreased whilst immunoreactivity of aromatase and 17 alpha-lyase were gradually decreased. These data suggest that the mechanism of the loss of aromatase activity from the granulosa cells of atretic follicles appears to differ from that in cycling follicles.(ABSTRACT TRUNCATED AT 250 WORDS)

Localization of aromatase in equine Leydig cells

Stallion testes secrete large amounts of estrogens, but the cellular location of the enzyme that converts androgens to estrogens, cytochrome P450 aromatase, has not been determined. The goal of the present study was to immunocytochemically localize stallion testicular aromatase using a polyclonal antibody generated against human placental cytochrome P450 aromatase. Testes were obtained from 12 stallions from 2 to 23 years of age, during both the breeding and non-breeding seasons. Immunoreactivity was confined to the Leydig cells in all testes examined. No immunostaining was observed in the Sertoli or germ cells. Heterogeneity in the level of immunostaining among individual Leydig cells was observed. The results of this study indicate that in postpubertal, adult, and aged stallions, testicular aromatase is located in Leydig cells.

Structure of the novel heme adduct formed during the reaction of human hemoglobin with BrCCl3 in red cell lysates

It was previously shown that the reductive debromination of BrCCl3 to trichloromethyl radical by human hemoglobin leads to formation of dissociable altered heme products, two of which are identical to those formed from myoglobin and one which is novel. In this study, we have elucidated the structure of this novel adduct with the use of mass spectrometry, as well as 1H and 13C NMR as a substitution product of a -C(Cl) = CCl2 moiety for a beta-hydrogen atom on the prosthetic heme's ring I vinyl group. From studies with the use of 13C-enriched BrCCl3, it was determined that the added carbon atoms were derived from 2 eq of BrCCl3. A mechanism that involves multiple reductive events and a radical cation heme intermediate is proposed. Consistent with this mechanism, cellular reductants were found to selectively enhance the amount of this novel dissociable heme adduct. These studies reveal fine differences between myoglobin and hemoglobin in the accessibility of reactive intermediates to the ring I vinyl group, as well as the potential importance of cellular reductants on the course of heme alteration.

Suicide inactivation of aromatase in human placenta and uterine leiomyoma by 5 alpha-dihydronorethindrone, a metabolite of norethindrone, and its effect on steroid-producing enzymes

Norethindrone (NET; 17 alpha-ethynyl-19-nortestosterone), a progestogen component of the contraceptive pill, irreversibly inhibits aromatase activity in human placental microsomes. However, it is known also to be aromatized in vitro and in vivo to produce a biologically very active estrogen called ethynylestradiol (EE2). It is therefore inappropriate to administer a high dose of NET to estrogen-dependent cancer patients for a prolonged time period. In this study, we focused on 5 alpha-dihydronorethindrone (5 alpha-DHNET), a metabolite of NET that is not aromatizable, and the inhibitory effects of 5 alpha-DHNET on human placental and uterine leiomyoma microsomal aromatase and other steroid synthetases. 5 alpha-Dihydronorethindrone showed weak affinity for both estrogen and progestogen receptors. It inhibited significantly human placental aromatase activity in a dose-dependent manner (Ki = 9.0 mumol/l; Kinact = 0.024/min), as well as that of uterine leiomyoma, but did not influence cholesterol side-chain cleavage or 17 alpha-hydroxylase, 21-hydroxylase or 11 beta-hydroxylase activities. These results suggest that 5 alpha-DHNET may be useful as an aromatase inhibitor, whose use in large doses is expected to reduce the size of estrogen-dependent tumors.

Selective inhibition of the 12-lipoxygenase pathway of arachidonic acid metabolism by L-arginine or sodium nitroprusside in intact human platelets

L-arginine (1-100 microM) or sodium nitroprusside (1-100 microM) caused a concentration dependent decrease in the metabolism of exogenously added arachidonic acid via the 12-lipoxygenase pathway in intact human platelets, as determined by the use of an HPLC assay. NG-monomethyl-L-arginine, but not the D-isomer of this compound, diminished the inhibitory effect of L-arginine. The D isomer of arginine had no effect. The cyclooxygenase pathway was much less susceptible to these effects. This study indicated that nitric oxide formed in intact human platelets selectively inhibited 12-lipoxygenase over that of cyclooxygenase and suggests that such inhibition may be an important regulatory mechanism.

Neuronal aromatase expression in preoptic, strial, and amygdaloid regions during late prenatal and early postnatal development in the rat

Brain aromatase has been considered to be an important clue in elucidating the actions of androgen on brain sexual differentiation. Using highly specific anti-P450arom antiserum, the regional and subcellular distributions were immunohistochemically evaluated in the preoptic, strial, and amygdaloid regions of developing rat brains. Aromatase-immunoreactive (AROM-I) neurons were classified into three groups. The first, in which immunostaining occurs only during certain pre- or neonatal days (E16-P2), included the anterior medial preoptic nucleus, the periventricular preoptic nucleus, neurons associated with the strial part of the preoptic area, and the rostral portion of the medial preoptic nucleus. The second is a striking AROM-I cell group in the "medial preopticoamygdaloid neuronal arc," which extends from the medial preoptic nucleus to the principal nucleus of the bed nucleus of the stria terminalis and the posterodorsal part of the medial amygdaloid nucleus. The AROM-I neurons appeared by E16, reaching a peak in staining intensity between E18 and P2 and diminishing after the perinatal stage. After P14, a third group of AROM-I neurons emerged in the lateral septal nucleus, the oval nucleus of the bed nucleus of the stria terminalis, and the central amygdaloid nucleus. The second group was thought to be the major aromatization center in developing rat brains, while the center might partly shift to the third group of neurons after the late infantile stage. The distribution and developmental patterns were basically similar in males and females, suggesting that the neonatally prominent aromatase is not induced by male-specific androgen surges occurring around birth. On immunoelectron microscopy, subneuronal aromatase was predominantly localized on the nuclear membrane and endoplasmic reticulum, which appeared to be appropriate for the efficient conversion of androgen into estrogen just prior to binding to the nuclear receptors.

6H-pyrazolo[4,5,1-de]acridin-6-ones as a novel class of antitumor agents. Synthesis and biological activity

The 7-substituted 6H-pyrazolo[4,5,1-de]acridin-6-ones with (aminoalkyl)amino and/or (hydroxyalkyl)amino groups in the side chains were synthesized by bromination using N-bromosuccinimide and the subsequent reaction with amines from the 7-substituted 5-bromo-2-methyl-6H-pyrazolo-[4,5,1-de]acridin-6-one. The substitution reaction of the amines with alkyl bromide (the C2 position) and aryl bromide (the C5 position) was accomplished by choosing the proper reaction conditions. These compounds show DNA intercalating ability in ethidium fluorescence assay and antiproliferative activity against Hela S3 cells. Impressive antitumor activity in vivo against murine P388 leukemia and murine sarcoma 180 solid tumor in mice was demonstrated for the 7-hydroxy analogs. In addition, some of these showed excellent antitumor activity against adriamycin-resistant murine P388 leukemia (P388/ADM) in mice.

Immunocytochemical localization of aromatase in the ovary of superovulated cattle, pigs and sheep

The localization of aromatase, an enzyme converting androgens to estrogen, in the ovaries of superovulated cattle, pigs and sheep was studied immunocytochemically in the preovulatory and postovulatory period using anti-human placental aromatase cytochrome P-450 antiserum. Immunostaining for aromatase was detected in the granulosa cells of preovulatory follicles of all species studied. Theca interna cells were stained in preovulatory follicles in the pig but not in cattle and sheep. Interstitial gland cells, cumulus cells and oocytes were unstained in all species. In cattle and pig the corpora lutea were unstained whereas they displayed staining in the sheep. Preantral and small antral follicles were unstained during both the preovulatory and postovulatory period in all species. It is concluded that granulosa cells of preovulatory follicles are the main residence for aromatase activity in superovulated cattle, pig and sheep, whereas the activity of theca interna and corpora lutea is species specific.

Tobacco alkaloid derivatives as inhibitors of breast cancer aromatase

The 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). MDA-MB-231 cells induced by 250 nM dexamethasone or 1 mM (Bt)2cAMP were slightly more sensitive to both inhibitors. Kinetic analyses showed that inhibition by N-(4-hydroxyundecanoyl)anabasine is competitive with respect to androstenedione as substrate, with apparent Ki values of 0.2 microM against microsomal aromatase activity derived from both (Bt)2cAMP-induced MDA-MB-231 cells and human breast tumor tissue. The corresponding apparent Ki against human placental microsomal aromatase activity was 0.4 microM. These results indicate that acyl derivatives of nornicotine and anabasine block estrogen formation in breast tumor cells and tissue and could contribute to the decreased intra-tissue estrogen levels in women who smoke.