bluuebunny/crossref_metadata_2025_split huggingface dataset:
Retinoic Acid Receptors and Retinoids Are Up-Regulated in the Developing and Adult Rat Prostate by Neonatal Estrogen Exposure
Authors: Prins Gail S. , Chang William Y. , Wang Yan , van Breemen Richard B. 
Published: August 2002

AbstractExposure to estrogens during the neonatal period interrupts rat prostatic development by reducing branching morphogenesis and by blocking epithelial cells from entering a normal differentiation pathway. Upon aging, ventral prostates exhibit extensive hyperplasia, dysplasia, and massive lymphocytic infiltrate, suggesting that neonatal estrogens may predispose the prostate gland to precancerous lesions. Vitamin A (retinol) and their derivatives (retinoic acids) are known key developmental regulators that bind and activate retinoic acid receptors (RARs). To evaluate whether neonatal estrogenization alters the sensitivity of the developing rat prostate to retinoids, RARα, -β, and -γ cellular localization and protein levels were analyzed over the course of development and into adulthood by immunocytochemistry and Western analysis, whereas mRNA levels were measured using RT-PCR. In addition, intraprostatic retinol and retinoic acid levels were quantitated on d 10 and 90 using HPLC-mass spectroscopy. Male rats were given 25 μg estradiol benzoate or oil on d 1, 3, and 5 of life, and prostatic complexes were removed on d 6, 10, 15, 30, and 90. The RARs localized to distinct cell populations: RARβ was expressed within basal epithelial cells, RARα was localized to differentiated luminal epithelial cells and smooth muscle cells, and RARγ was expressed within periductal stromal cells. Over the normal course of development, total protein and mRNA levels for the RARs declined, so that the adult prostate possessed the lowest amounts of RAR. Exposure to estrogens during the neonatal period resulted in an immediate and sustained increase in RARα levels and in the number of cells that expressed RARβ, whereas RARγ levels were unaffected. Western analysis confirmed that total prostatic RAR protein levels were significantly increased, whereas RT-PCR demonstrated that RARα and RARβ mRNA levels were markedly elevated in response to estrogenic exposure. The total prostatic retinol content was tripled by estrogenic exposure on d 10 and 90, indicating that the ability to retain retinoids within the prostate was permanently increased. Intraprostatic levels of 9-cis- and all-trans-retinoic acid levels were reduced on d 10, whereas 13-cis-retinoic acid levels were increased in response to estrogens. In the adult prostates of rats exposed neonatally to estrogen, total retinoic acid levels were doubled due to significant increases in both 9-cis- and 13-cis-retinoic acids compared with those in control prostates. In summary, levels of specific RARs and their activating ligands are increased in the prostate gland after neonatal estrogenic exposure, and this effect is permanent throughout the life of the animal. Thus, we hypothesize that alterations in morphogenesis as well as dysplasia in the adult prostate may be mediated in part through augmentation of transcriptional signals in the retinoid pathway.
Stimulation of Hepatic Signal Transducer and Activator of Transcription 5b by GH Is Not Altered by 3-Methylcholanthrene
Authors: Timsit Yoav E. , Riddick David S. 
Published: August 2002

AbstractWe are investigating the mechanisms by which aromatic hydrocarbons, such as 3-methylcholanthrene (MC), suppress hepatic cytochrome P450 2C11 (CYP2C11) gene expression. CYP2C11 is an enzyme expressed in the liver of male rats and is regulated by a pulsatile pattern of GH secretion. We have previously shown that MC attenuates the stimulatory effect of GH on CYP2C11 expression in hypophysectomized male rats. In follow-up studies we evaluated the effect of MC on GH-stimulated signal transducer and activator of transcription 5b (STAT5b) phosphorylation, nuclear translocation, and DNA-binding activity. GH-stimulated increases in hepatic nuclear STAT5b and phospho-STAT5b levels were not different between groups of hypophysectomized rats receiving MC or vehicle. This observation was corroborated at the DNA-binding level by EMSA. We also measured GH-induced STAT5b activation in the H4IIE rat hepatoma cell line. STAT5b DNA-binding activity detected in GH-treated cells was not affected by MC. Immunocytochemistry experiments revealed no effect of MC on GH-stimulated STAT5b nuclear translocation in H4IIE cells. These in vivo and in vitro data suggest that interference with GH-stimulated STAT5b activation does not constitute a mechanism by which MC attenuates the stimulatory effect of GH on CYP2C11 gene expression.
Calcium Dynamics and Resting Transcriptional Activity Regulates Prolactin Gene Expression
Authors: Villalobos Carlos , Núñez Lucía , Faught William J. , Leaumont David C. , Boockfor Fredric R. , Frawley L. Stephen 
Published: August 2002

AbstractResearch on the regulation of hormone gene expression by calcium signaling is hampered by the difficulty of monitoring both parameters within the same individual, living cells. Here we achieved concurrent, dynamic measurements of both intracellular Ca2+ concentration ([Ca2+]i) and prolactin (PRL) gene promoter activity in single, living pituitary cells. Cells were transfected with the luciferase reporter gene under control of the PRL promoter and subjected to bioluminescence and fluorescence imaging before and after presentation of TSH-releasing hormone (TRH), a prototypic regulator of PRL secretion and gene expression that induces a transient Ca2+ release, followed by sustained Ca2+ influx. We found that cells displaying specific photonic emissions (i.e. mammotropes) showed heterogeneous calcium and transcriptional responses to TRH. Transcriptionally responsive cells always exhibited a TRH-induced [Ca2+]i increase. In addition, transcriptional responses were related to the rate of Ca2+ entry but not Ca2+ release. Finally, cells lacking transcriptional responses (but showing [Ca2+]i rises) exhibited larger levels of resting PRL promoter activity than transcriptionally responsive cells. Thus, our results suggest that the sustained entry of Ca2+ induced by TRH (but not the Ca2+ release) regulates transcriptional responsiveness. Superimposed on this regulation, the previous, resting PRL promoter activity also controls transcriptional responses.
Ghrelin Stimulates GH But Not Food Intake in Arcuate Nucleus Ablated Rats
Authors: Tamura Hideki , Kamegai Jun , Shimizu Takako , Ishii Shinya , Sugihara Hitoshi , Oikawa Shinichi 
Published: August 2002

Abstract
Ghrelin, an endogenous ligand for the GH secretagogue receptor 1a (GHS-R1a), was originally purified from the rat stomach. Ghrelin mRNA and peptide have also been detected in the hypothalamus and pituitary. Ghrelin is a novel acylated peptide that regulates GH release and energy metabolism. GHS-R1a mRNA is expressed in the pituitary gland as well as in several areas of the brain including the hypothalamus. In this study, we examined whether ghrelin could stimulate GH secretion and feeding in chronic GHRH, neuropeptide Y, and agouti-related protein deficient rats that were neonatally treated with monosodium glutamate (MSG), which destroys the neurons in the hypothalamic arcuate nucleus (ARC). Intravenous (iv) administration of rat ghrelin (10 μg/kg body weight) increased plasma GH levels significantly in the normal adult male rats during a GH trough period of pulsatile GH secretion, while iv injection of ghrelin in MSG-treated rats resulted in a markedly attenuated GH response. When rat ghrelin (10 μg/rat) was administered intracerebroventricular (icv), plasma GH levels were increased comparably in normal control and MSG-treated rats. However, the GH release after icv injection of ghrelin was markedly diminished compared with that after iv administration of a small amount of ghrelin in normal control rats (icv: 10 μg/rat, iv: approximately 4.0 μg/rat), indicating that the GH-releasing activity of exogenous ghrelin is route dependent and at least in part via hypothalamic ARC. The icv administration of 1 μg of ghrelin increased significantly 4-h food intake in normal control, whereas the peptide did not increase food intake in MSG-treated rats, indicating that the feeding response to ghrelin requires intact ARC. Taken together, the primary action of ghrelin on appetite control and GH releasing activity is via the ARC even though it might act on another type of GHS-R besides GHS-R1a.
Regulation of Microsomal P450, Redox Partner Proteins, and Steroidogenesis in the Developing Testes of the Neonatal Pig
Authors: Moran F. M. , Ford J. J. , Corbin C. J. , Mapes S. M. , Njar V. C. , Brodie A. M. , Conley A. J. 
Published: August 2002

AbstractTesticular growth and plasma androgen concentrations increase markedly in the first weeks of neonatal life of pigs. The regulation of steroidogenesis through this period was examined by measuring total microsomal cytochromes P450 (P450), 17α-hydroxylase/17,20-lyase P450 (P450c17) and aromatase P450 (P450arom) enzyme activities, and the redox partner proteins nicotinamide adenine dinucleotide phosphate, reduced form (NADPH)-cytochrome P450 reductase (reductase) and cytochrome b5 in testicular microsomes. Testes were collected from 1–24 d of age, and testicular development was suppressed by a GnRH antagonist in some animals from d 1–14. Both 17/20-lyase and aromatase activities increased from d 1–7 but not thereafter, and 17–20-lyase activity was always at least 200-fold higher than aromatase activity. Reductase decreased in wk 1, then increased to d 24. No changes were seen in cytochrome b5 expression. GnRH antagonist treatment suppressed plasma LH, testosterone and testes growth to d 14. 17,20-Lyase and aromatase activities in testicular microsomes were reduced by 20% and 50%, respectively. Total microsomal P450 concentration was reduced by 50% on d 7, but there was no effect of treatment on reductase or cytochrome b5 expression. These data support the hypothesis that the rise in neonatal testicular androgen secretion is more likely due to gonadotropin-stimulated gonadal growth, rather than specific P450c17 expression. Neither P450c17 nor P450arom can account for the decline in total microsomal P450. Reductase and cytochrome b5 expression appears to be constitutive, but reductase levels saturate both P450c17 and P450arom.
Postnatal Growth and Circulating ACTH and Cortisol Concentratoins during the First Month of Life in Cloned Lambs
Authors: Edwards Lisa , Peura Teija , Hartwich Katrina , Rudiger Skye , McMillen I. Caroline , Walker Simon 
Published: August 2002

Abstract
Recent studes have indicated that there is a decrease in perinatal survival of apparently normal animals produced by somatic-cell nuclear transfer. Here we report that the cortisol and adrenocorticotrophic hormone (ACTH) profiles of cloned lambs in the first 4 weeks of life are significantly different to that of control lambs. The growth of cloned lambs however was not different to controls. These findings demonstrate that endocrine development may be altered in apparently “normal” clones.
Review: Organotin compounds and their therapeutic potential: a report from the Organometallic Chemistry Department of the Free University of Brussels
Authors: Gielen Marcel 
Published: August 2002

AbstractAn overview of the development of antitumour organotin derivatives is presented and discussed for selected classes of compounds, such as tetraorganodicarboxylatodistannoxanes and related diorganotin dicarboxylates, and for triorganotin carboxylates. Among the carboxylate groups used are steroidcarboxylates and other biologically relevant carboxylates. High to very highin vitroactivities have been found, sometimes equalling that of doxorubicin. Solubility in water is an important issue, dominating thein vivotesting of compounds. Polar substituents, like fluorine or polyoxaalkyl moieties, improve the water solubility. Although organotin derivatives constitute a separate class of compounds, the comparison with cisplatin is inevitable. Among the observed toxicities, neurotoxicity, known from platinum cytostatics, and gastrointestinal toxicity, typical for many oncology drugs, have been detected, but to a lower extent. Further research to develop novel useful organotin antitumour compounds needs to be carried out. Copyright © 2002 John Wiley & Sons, Ltd.
Cobalt(II) tri‐tert‐butoxysilanethiolates: in search of models for catalytic metal site of liver alcohol dehydrogenase
Authors: Becker Barbara , Pladzyk Agnieszka , Konitz Antoni , Wojnowski Wieslaw 
Published: August 2002

AbstractThe reaction of dimeric [Co{SSi(OtBu)3}2(NH3)]2 (1) with 2‐picoline at 0 °C leads to the formation of a thiolate complex [Co{SSi(OtBu)3}2(NH3)(2‐Pic)] (3), with two different nitrogen ligands in the cobalt(II) coordination sphere. Dissolution of 1 in acetonitrile gives one cobalt(II) thiolate complex with two ammine ligands bonded to metal: [Co{SSi(OtBu)3}2(NH3)2]·MeCN (4). A second, unique, aqua‐ligated cobalt(II) thiolate — [Co{SSi(OtBu)3}3(H2O)]− +HNEt3 (5) — forms when CoCl2 reacts with an excess of (tBuO)3SiSH in the presence of triethylamine in water. The structures of 3, 4 and 5 were determined by X‐ray structure methods, revealing a distorted tetrahedral arrangement of ligands around cobalt. Under normal conditions, all three complexes are unstable. 3 loses ammonia to give stable [Co{SSi(OtBu)3}2(2‐Pic)] (2). A reverse reaction is also possible. Moreover, 2 is able to capture water, and there is spectral evidence that a complex [Co{SSi(OtBu)3}3(H2O)(2‐Pic)] with a CoNOS2 core, mimicking the cobalt‐substituted liver alcohol dehyrogenase active site, is formed in solution. Copyright © 2002 John Wiley & Sons, Ltd.
Grignard reagents in toluene solutions
Authors: Sassian M. , Panov D. , Tuulmets A. 
Published: August 2002

AbstractGrignard reagents were prepared from chloroalkanes and chlorobenzene in toluene in the presence of one or 0.5 equivalents of various organic bases (ethers and amines). Reagents with an average monosolvation can be obtained in high yields from primary or secondary alkyl chlorides and chlorobenzene. Diethyl ether is the most effective donor, in that it affords the reagents with a very small content of base. The kinetics of the reactions of n‐butylmagnesium chloride in diethyl ether, and of this Grignard reagent monosolvated with the ether in toluene, with alkylalkoxysilanes were investigated. Reactivity of the partially solvated reagent greatly exceeds that of the conventional Grignard reagent. Yields of addition and reduction reactions of mono‐ and semi‐solvated n‐butylmagnesium chlorides in toluene with a ketone, an aldehyde, and two esters were determined. The partially solvated reagents afford the addition products (tertiary alcohols) in yields better than, or at least comparable to, those obtained with the conventional Grignard reagents. Copyright © 2002 John Wiley & Sons, Ltd.
Communication: A complex with the cyclo‐R2Sb2S2 [R = CH(SiMe3)2] ligand
Authors: Breunig Hans Joachim , Ghesner Ioan , Lork Enno 
Published: August 2002

AbstractThe reaction of the cyclo oligomers R
nSb
nS
n [n = 2, 3; R = CH(SiMe3)2] with W(CO)5thf (thf = tetrahydrofuran) in thf results in trapping of the dimer in cyclo‐[R2Sb2S2][W(CO)5]2 (1). An X‐ray crystal structure analysis revealed that the complex contains a four‐membered antimony–sulfur ring in an almost planar conformation, where the alkyl groups occupy cis positions and the W(CO)5 units are bonded trans to the alkyl groups on the antimony atoms. Copyright © 2002 John Wiley & Sons, Ltd.
Review: Applications of novel sterically demanding aromatics in organometallic synthesis
Authors: Steele Barry R. , Micha‐Screttas Maria , Screttas Constantinos G. 
Published: August 2002

AbstractCatalytic amounts of the mixed reagents n‐BuLi and LiK(OCH2CH2NMe2)2 in combination with Mg(OCH2CH2OEt)2 promote the multiple and clean addition of ethylene to a series of alkyl aromatics to produce sterically demanding aromatic hydrocarbons and their functional derivatives. Copyright © 2002 John Wiley & Sons, Ltd.
Review: Synthesis of organometallics and catalytic hydrogenations in ionic liquids
Authors: Dyson Paul J. 
Published: August 2002

AbstractNew solvents provide synthetic chemists with the opportunity of conducting new reactions and carrying out new processes. In this paper the author's own work on organometallic chemistry in ionic liquids is reviewed and placed in context with studies from other groups in this area. Specifically, the paper will describe the use of ionic liquids in the synthesis of organometallic complexes and clusters and the use of ionic liquids in hydrogenation catalysis. The synthesis and reactivity of ionic liquids with organometallic anions will also be discussed. Copyright © 2002 John Wiley & Sons, Ltd.
N‐Pyrrolyl‐[N,N,N]‐bis(imino)pyridyl iron(II) and cobalt(II) olefin polymerization catalysts
Authors: Amort Christoph , Malaun Michael , Krajete Alexander , Kopacka Holger , Wurst Klaus , Christ Maria , Lilge Dieter , Kristen Marc O. , Bildstein Benno 
Published: August 2002

AbstractA series of new [N,N,N] 2,6‐bis(imino)pyridyl iron and cobalt halide complexes as precatalysts for the homo‐ and co‐polymerization of ethylene has been synthesized and evaluated for their catalytic performance. The novel key structural feature of these [N,N,N]MCl2 catalysts is their peripheral substitution with bulky N‐heterocyclic groups, including substituted N‐pyrrolyl, N‐indolyl, N‐carbazolyl, and N‐triazolyl moieties. The synthesis starts with the corresponding N‐amino‐N‐heterocycles, which were prepared by a modified Paal–Knorr condensation of 1,4‐diketones with mono‐protected hydrazines, or by electrophilic amination of benzannelated azoles. Condensation with 2,6‐diacetylpyridine or 2,5‐diformylthiophene afforded 14 different terdentate ligands, and complex formation with iron(II), iron(III), cobalt(II) yielded 23 different precatalysts. A single crystal structure analysis of one representative showed that these paramagnetic complexes have a distorted trigonal bipyramidal structure with orthogonal sterically shielding N‐azolyl groups. All the methylalumoxane‐activated iron(II) and cobalt(II) complexes with N‐pyrrolyl, N‐indolyl, and N‐carbazolyl substituents are highly active catalysts for the homo‐ and co‐polymerization of ethylene, producing polymers with comparatively narrow molecular weight distributions and with a wide range of molecular weights, dependent on the substitution pattern of the peripheral N‐azolyl substituents. The observed microstructures of the polymers vary from very highly branched to mostly linear, giving access to oligomers and polymers with an unusual broad spectrum of macroscopic physical properties. Copyright © 2002 John Wiley & Sons, Ltd.
Oxidative dehydrodimerization of manganese vinylidene complexes (η5‐C5R5)(CO)(L)MnCCHPh (R = Me, L = CO; R = H, L = PPh3)
Authors: Novikova Lyudmila N. , Peterleitner Mikhail G. , Sevumyan Karine A. , Semeikin Oleg V. , Valyaev Dmitri A. , Ustynyuk Nikolai A. 
Published: August 2002

AbstractThe oxidative dehydrodimerization of the phenylvinylidene manganese complexes (η5‐C5R5)(CO)(L)MnCCHPh (5: R=Me, L=CO; 6: R=H, L=PPh3) into the corresponding bis‐vinylidene compounds (η5‐C5R5)(CO)(L)MnCCPhCPhCMn(CO)(L)(η5‐C5R5) (7: R=Me, L=CO; 8: R=H, L=PPh3) was studied by cyclic voltammetry and chemical experiments. It was found that dehydrodimerization of 5 and 6 proceeds via direct C(β)C(β) coupling of the radical cations 5
+· and 6
+· to give dicationic bis‐carbyne complexes [(η5‐C5R5)(CO)(L)Mn≡CCPhHCPhHC≡Mn(CO)(L)(η5‐C5R5)]2+ (10
++: R=Me, L=CO; 11
++: R=H, L=PPh3), which can be converted into bis‐vinylidene complexes 7 and 8 respectively by reduction with (η‐C6H6)2Cr. In this process, binuclear 19‐electron bis‐carbyne compounds 10
·· and 11
·· undergo further transformation into the dimers 7 and 8 via homolysis of C(β)H bonds of the bis‐carbyne ligand, thus exhibiting rare examples of reductive activation of CH bonds in 19‐electron transition metal carbyne complexes. Copyright © 2002 John Wiley & Sons, Ltd.
Synthesis and biological activity of ‘3 + 1’ mixed ligand (3‐thiapentane‐1,5‐dithiolato)oxorhenium(V) complexes bearing 1,2,3,4‐tetrahydro(iso)quinoline and quinoline
Authors: Zablotskaya Alla , Segal Izolda , Germane Skaidrite , Shestakova Irina , Lukevics Edmunds , Kniess Torsten , Spies Hartmut 
Published: August 2002

Abstract‘3 + 1’ mixed ligand oxorhenium(V) complexes of the type ReO(SSS)S(CH2)
nHetN have been synthesized by the reaction of the preliminary prepared tetrahydro(iso)quinolyl containing monodentate ligands with chloro(3‐thiapentane‐1,5‐dithiolato)oxorhenium(V). The newly synthesized ligands and complexes were characterized by elemental analysis, IR, 1H, and 13C NMR spectroscopy. Metal complexes were screened for psychotropic and antitumour activities and receptor‐binding properties and were found to be active in this respect. Copyright © 2002 John Wiley & Sons, Ltd.
Some platinum(II) complexes derived from aromatic alkynes
Authors: Bruce Michael I. , Davy Julianne , Hall Ben C. , Galen Yvonne Jansen van , Skelton Brian W. , White Allan H. 
Published: August 2002

AbstractSeveral trans‐platinum(II) complexes, of the type R′{Pt(PBu3)2}R″{Pt(PR3)2}R′, where R′ and R″ are groups derived from a series of aromatic alkynes and diynes, have been prepared and characterized. Extensive spectroscopic data for these and other known related complexes are presented. A more precise structural study of trans‐Pt(C≡CC6H4C≡CPh)2(PBu3)2 (cf. Z. Kristallogr. 1998; 213: 483) is reported. Copyright © 2002 John Wiley & Sons, Ltd.
Di‐n‐butyltin aminoarylcarboxylates: structure, properties and in vitro antitumor activity
Authors: Pruchnik Florian P. , Bańbuła Małgorzata , Ciunik Zbigniew , Chojnacki Henryk , Latocha Małgorzata , Skop Barbara , Wilczok Tadeusz 
Published: August 2002

AbstractThe properties and structures of the tetranuclear dibutyltin complexes [Sn4(µ3‐O)2(C4H9‐n)8­{OOCC6H3(NH2)2‐3,4}4] (1), [Sn4(µ3‐O)2(C4H9‐n)8{OOCC6H3(NH2)2‐3,5}4] (2), [Sn4(µ3‐O)2(C4H9‐n)8­{OOC‐2‐C6H4NNC6H4N(CH3)2‐4}4] (3) are described. Complex 3 adopts a structure with a tetranuclear Sn4(µ3‐O)2 core. All tin atoms are five‐coordinate and form bonds with three oxygen atoms and two butyl ligands. Two carboxylates are bridging and two are terminal ligands. IR and NMR spectra indicate that the same structure is adopted by complexes 1 and 2. The molecular and electronic structures of complex 1 of C
i symmetry have been studied using the semi‐empirical PM3 formalism. The calculated structure and bond distances agree with X‐ray data. All complexes are effective antitumor agents. Copyright © 2002 John Wiley & Sons, Ltd.
UV laser photolysis of silacyclopent‐3‐ene: effect of admixtures on nature of chemically vapour‐deposited organosilicon films
Authors: Urbanová Markéta , Pola Josef 
Published: August 2002

AbstractExamination of ArF laser‐induced gas‐phase photolysis of silacyclopent‐3‐ene, occuring as extrusion of silylene, in the presence of admixtures reveals that photolysis is not interfered with in the presence of N2, CO and CO2, but it is in the presence of O2, 2‐C4F8, CH3OH, CD3OH, CF3CH2OH and CH3CO2H. Formation of volatile products and solid deposited films incorporating fluorine or oxygen atoms is interpreted in terms of reactions of silylene with the admixtures. Copyright © 2002 John Wiley & Sons, Ltd.