bluuebunny/crossref_metadata_2025_split huggingface dataset:
A challenging synthesis of new 1,3,4‐thiadiazole derivatives starting from 2‐acylamino‐3,3‐dichloroacrylonitriles
Authors: Golovchenko Oleksandr V. , Pilyo Stepan G. , Brovarets Vladimir S. , Chernega Alexander N. , Drach Boris S. 
Published: September 2004

AbstractAvailable 2‐acylamino‐3,3‐dichloroacrylonitriles, when treated with hydrazine hydrate, provide 2‐alkyl‐ or 2‐aryl‐5‐hydrazino‐1,3‐oxazole‐4‐carbonitriles that readily add alkyl or aryl isothiocyanates and the adducts formed recyclize on heating. Finally, the synthesis results in 5‐alkyl(aryl)amino‐1,3,4‐thiadiazol‐2‐yl(acylamino)acetonitriles or the products of their further cyclization, 2‐(5‐amino‐1,3‐ oxazol‐2‐yl)‐1,3,4‐thiadiazole derivatives. The structures of the novel substituted 1,3,4‐thiadiazoles are corroborated spectroscopically as well as by X‐ray diffraction method. © 2004 Wiley Periodicals, Inc. Heteroatom Chem 15:454–458, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20041
Nitrogen heterocycles from trimethylbenzenes
Authors: Shklyaev Yu. V. , Ismagilov R. R. , Rozhkova Yu. S. , Fatykhov A. A. , Abdrakhmanov I. B. , Tolstikov A. G. , Dembitsky V. M. 
Published: September 2004

AbstractThe reaction between 1,2,4‐trimethylbenzene 1, isobutyric aldehyde, and cyanoacetic ester afforded a mixture of three products: 3,3,5,6,8‐ pentamethyl‐1,2,3,4‐tetraisoquinolylidene‐1‐acetic acid ether (2) and its 3,3,5,6,7‐pentamethyl‐(3)‐ and 3,3,6,7,8‐pentamethyl‐1,2,3,4‐tetraisoquinolyli‐ dene‐1‐acetic acid ether isomers (3) in ratio 1:5:1. © 2004 Wiley Periodicals, Inc. Heteroatom Chem 15:471–476, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20045
Fossil hyrax dung and evidence of Late Pleistocene and Holocene vegetation types in the Namib Desert
Authors: Scott Louis , Marais Eugene , Brook George A. 
Published: September 2004

AbstractPollen was derived from fossil dung of herbivorous hyraxes, deposited in a rock shelter on the highest mountain in Namibia, Dâures or Brandberg, situated on the Namib Desert margin. Radiocarbon dating ranging in age between modern times and 30 000 yr BP showed it represents the first empirical pollen evidence of continental palaeovegetation during the Late Pleistocene along the western escarpment of southern Africa. The initial results indicate Last Glacial Maximum vegetation differed totally from the current pattern as vegetation types were dominated by small Asteraceae shrubs, in contrast to those of the Holocene and modern times which show more succulents, grass and woody elements (arboreal pollen). The results suggest that Cape floral communities did not reach into the tropics along the western escarpment of Africa, despite such pollen types occurring in marine cores. Copyright © 2004 John Wiley & Sons, Ltd.
Surface‐enhanced Raman scattering of 3‐mercaptopropionic acid adsorbed on a colloidal silver surface
Authors: Castro J. L. , López‐Ramírez M. R. , Arenas J. F. , Otero J. C. 
Published: September 2004

AbstractChemisorption of 3‐mercaptopropionic acid (3MPA) on a colloidal silver surface was investigated using surface‐enhanced Raman scattering (SERS). The ν(SH) vibration has never been observed in the SERS of 3MPA recorded over a wide range of pH. That behaviour enables us to deduce that the SH group is deprotonated and links to the metal forming an AgS bond but, in contrast, the carboxylic or carboxylate groups do not link to the metal. The carboxylic group is preserved even at pH values at which they should be deprotonated and only under rather basic conditions (pH ≥ 8) do the carboxylic groups dissociate. Consequently, the behaviour of 3MPA adsorbed on colloidal silver is analogous to that observed by Kudelski on a silver electrode. Finally, it is observed in all the SERS spectra recorded at any pH that it is the T‐conformer, defined around the C(2)C(3) bond, which adsorbs preferentially. Copyright © 2004 John Wiley & Sons, Ltd.
Micellar effects on a ligand substitution reaction: Kinetics of the formation of [Fe(CN)5(μ‐pz)Ru(NH3)5]−, from [Fe(CN)5H2O]3− and [Ru(NH3)5pz]2+, in the presence of anionic micelles
Authors: Jiménez Rafael , Bueno Elena , Cano Israel , Corbacho Elizabeth , Fernández M. Eugenia , Gómez Lidia , Graciani Jesús , Hernández María , Matitos M. Teresa , Ortíz José , López‐Cornejo Pilar , Prado‐Gotor Rafael 
Published: September 2004

AbstractThe kinetics of substitution of H2O by Ru(NH3)5pz2+ (pz = pyrazine) in Fe(CN)5H2O3− have been studied in micellar aqueous solutions of sodium dodecylsulfate (SDS). Experimental results are discussed by using an approach based on the transition‐state theory. This approach is better than others based on the pseudophase model, which can also be used, because it is able to give a clear meaning to the parameters of the model. Trends in the observed reactivity are explained by a change in the degree of association of one of the reactants to the micelles (Ru(NH3)5pz2+ in the present work). This association is governed by an equilibrium constant that depends on the electrostatic potential at the surface of the micelles. © 2004 Wiley Periodicals, Inc. Int J Chem Kinet 36: 627–633, 2004
Kinetics of N‐bromination of 2‐oxazolidinone
Authors: Amoedo F. A. , Antelo J. M. , Arce F. , Parajó M. , Teixeiro E. 
Published: September 2004

AbstractThe kinetics of N‐bromination of 2‐oxazolidinone by transfer of Br from sodium hypobromite, N‐bromosuccinimide (NBS), or N‐bromoacetamide (NBA) were determined spectrophotometrically, at pH between 4.6 and 12.45 (depending on the brominating agent). The reaction with hypobromite was of first order with respect to both the hypobromite and the substrate. The bromination of oxazolidinone with NBS (or NBA) has been found to be a reversible process of order one with respect to both NBA (or NBA) and oxazolidinone in the forward direction, and order one with respect to SI (or ACAM) and the resulting N‐bromo‐oxazolidinone in the other. The pH dependence of the reaction rate was in keeping with a mechanism in which all the brominating agents (HOBr, BrO−, NBS and NBA) react predominantly with the anion of the substrate. Bimolecular bromination rate constants increased in the order BrO− < NBA < NBS < HOBr. © 2004 Wiley Periodicals, Inc. Int J Chem Kinet 36: 642–649, 2004
A study on the hydrolysis of bis(nitrophenyl)phosphate catalyzed by N‐methyldiethanolamine‐Ce(III) complex
Authors: Yuanqin Zhang , Fan Liu , Qingxiang Xiang , Junru Xiong 
Published: September 2004

AbstractThe hydrolysis of bis(p‐nitrophenyl)phosphate (BNPP) catalyzed by N‐methyldiethanolamine‐Ce(III) complex in the presence and absence of cetyltrimethylammonium bromide (CTAB) and Brij35 surfactants at pH 7.20 and 303 K has been studied. The experimental results indicate that N‐methyldiethanolamine‐Ce(III) complex remarkably accelerates the hydrolysis of BNPP. The observed first‐order rate constant of the hydrolysis of BNPP catalyzed by N‐methyldiethanolamine‐Ce(III) complex at pH 7.20 and 303 K is 1.22 × 10−2 s−1, which is 1.09 × 109 times of that of spontaneous hydrolysis of BNPP at pH 7. It is close to the activity of natural enzyme. A general quantitative treatment of the catalytic reaction involved a ternary complex as MmLlS has also been proposed in this paper. Applying this method to the catalytic hydrolysis of BNPP, we have obtained its thermodynamic and kinetic parameters. CTAB and Brij35 surfactant micelles obviously influence the rate constants of the catalytic hydrolysis of BNPP. Brij35 micelles promote the catalytic hydrolysis of BNPP, while CTAB micelles inhibit it. © 2004 Wiley Periodicals, Inc. Int J Chem Kinet 36: 687–692, 2004
Tcf binding sequence and position determines β‐catenin and Lef‐1 responsiveness of MMP‐7 promoters
Authors: Gustavson Mark D. , Crawford Howard C. , Fingleton Barbara , Matrisian Lynn M. 
Published: September 2004

AbstractThe matrix metalloproteinase‐7 (MMP‐7) gene is a target of β‐catenin transactivation. Expression of the T‐cell factor, Lef‐1, enhances transcriptional activation of the human MMP‐7 promoter by β‐catenin, but represses activation of the mouse MMP‐7 promoter, both activities through consensus Tcf binding sites. The mouse promoter has a single Tcf binding element (mTBE) located downstream of the transcriptional start site, while the human promoter has two Tcf binding elements (hTBE1, hTBE2), both located upstream of the transcriptional start. hTBE1 and hTBE2 also differ in sequence from mTBE. Here we demonstrate that positioning of mTBE, upstream or downstream of the transcriptional start site dictated whether Lef‐1 functioned as an activator or repressor, respectively. Sequence differences between mTBE and hTBE sites determined the potency of these activities, with hTBE sites being weaker. Mutational analysis of mTBE showed that increased Lef‐1 activity mapped to G · C base pairings at 5′ and 3′ ends, and correlated with a threefold increase in Lef‐1 binding affinity in vitro. Heterologous promoters with high affinity binding sites were 115‐fold more responsive to β‐catenin than those with low affinity sites. Converting low affinity Tcf binding sites to high affinity sites increased β‐catenin responsiveness of the mouse and human promoters by 2–3 fold, and ectopic expression of Lef‐1 increased β‐catenin responsiveness for promoters with low affinity binding sequences. We concluded that sequence and position of Tcf binding sites can determine the extent of β‐catenin‐Lef‐1 responsiveness for β‐catenin target genes. © 2004 Wiley‐Liss, Inc.
Immunolocalization of bovine sperm protease BSp120 by light and electron microscopy during capacitation and the acrosome reaction: Its role in in vitro fertilization
Authors: cesari Andreina , Sánchez Jorge J. , Biancotti Juan C. , Vazquez‐Levin Mónica H. , Kaiser Germán , Palma Gustavo A. , Alberio Ricardo , Vincenti Amanda E. , FornÉs Miguel W. 
Published: September 2004

AbstractMammalian fertilization involves various steps in which the participation of specific enzymes has been demonstrated by numerous studies. Acrosin is one of the most widely acrosomal protease in mammalian spermatozoa studied, including bovine; however, other proteases have also been described. A new trypsin‐like serine protease named bovine serine protease of 120 kDa (BSp120) and its pre‐cursor BSp66 (66 kDa) were identified in bovine spermatozoa. Cytological and ultrastructural immunolocalization studies on BSp120 were performed in live and fixed cells. Immunoflorescence assays with specific polyclonal antibodies revealed localization of BSp120 on the sperm head, with a signal homogeneously distributed over the acrosome resembling a horseshoe. After the acrosome reaction, sperm showed a patchy pattern in the acrosomal cap. Immune electron microscopy analysis indicated that BSp120 is located over the head plasma membrane of capacitated spermatozoa and acrosome reacting spermatozoa. To assess BSp120 function in sperm‐oocyte interaction, in vitro fertilization studies were conducted. Oocytes were incubated with spermatozoa pre‐treated with anti‐BSp120, anti‐guinea pig acrosin, and anti‐BSp120 plus anti‐guinea pig acrosin. Pre‐treatment of bovine spermatozoa with antibodies towards each protein did not significantly modify fertilization rates. However, when both anti‐acrosin and anti‐BSp120 antibodies were simultaneously added, there was a significant decrease in the fertilization rate, suggesting that both enzymes may be required for fertilization. Altogether, the results from the present study described the localization of BSp120 over the acrosome of bovine sperm, and suggest its involvement in fertilization. Mol. Reprod. Dev. 69: 411–418, 2004. © 2004 Wiley‐Liss, Inc.
Species‐related differences in blastocyst quality are associated with differences in relative mRNA transcription
Authors: Rizos Dimitrios , Gutierrez‐Adan Alfonso , Moreira Pedro , O'Meara Ciara , Fair Trudee , Evans Alex C.O. , Boland Maurice P. , Lonergan Patrick 
Published: September 2004

AbstractThe objective of this study was to compare the relative transcript abundance of several important candidate genes between ovine and bovine blastocysts. Blastocysts were produced by in vitro maturation, fertilization, and subsequent culture in one of two formulations of synthetic oviduct fluid medium (SOF1 and SOF2). From each IVF replicate groups of 10 bovine and 10 ovine blastocysts from each of the two media were used for analysis of mRNA relative abundance. Transcript levels for mitochondrial Mn‐superoxide dismutase (MnSOD), survivin, and glucose transport 5 (Glut‐5) were significantly higher in ovine blastocysts than bovine (P < 0.05), while transcripts for Connexin 31 (Cx31), interferon tau (IFN‐τ), and sarcosine oxidase (SOX) were significantly more abundant in bovine blastocysts (P < 0.01). For the two remaining transcripts, E‐cadherin (E‐cad) and Na/K ATPase (Na/K), there was no difference. Culture of bovine embryos in SOF2 resulted in a significant increase in the level of expression of MnSOD and Glut‐5 (P < 0.05) compared to those bovine embryos cultured in SOF1. For all the other transcripts, except survivin, there was a significant decrease in the relative abundance. Culture of sheep embryos in either SOF1 or SOF2 did not have a major influence on transcript abundance; of the eight transcripts examined, the relative abundance of only one, SOX, was significantly altered. Bovine blastocysts produced in SOF2 had significantly higher survival rates at 24, 48, and 72 hr and significantly higher hatching rates following vitrification and warming than those cultured in SOF1 (P < 0.001). In conclusion, we have quantified for the first time the mRNA expression of a set of important developmental genes in sheep blastocysts and we have demonstrated that these differences between species in their adaptability to culture conditions, manifested in differences in embryo morphology and cryotolerance, are related to differences in mRNA relative abundance. The results also highlight the usefulness of transcript analysis as a marker of embryo quality. Mol. Reprod. Dev. 69: 381–386, 2004. © 2004 Wiley‐Liss, Inc.
Chorionic gonadotropin regulates the transcript level of VHL, p53, and HIF‐2α in human granulosa lutein cells
Authors: Herr D. , Keck C. , Tempfer C. , Pietrowski Detlef 
Published: September 2004

AbstractThe ovarian corpus luteum plays a critical role in reproduction being the primary source of circulating progesterone. After ovulation the corpus luteum is build by avascular granulosa lutein cells through rapid vascularization regulated by gonadotropic hormones. The present study was performed to investigate whether this process might be influenced by the human chorionic gonadotropin (hCG)‐dependent expression of different tumor suppressor genes and hypoxia dependent transcription factors. RNA was isolated from cultured granulosa lutein cells, transcribed into cDNA, and the transcript level of following genes were determined: RB‐1, VHL, NF‐1, NF‐2, Wt‐1, p53, APC, and hypoxia inducible factor‐1 (HIF‐1), ‐2, and ‐3α. Additionally, the influence of hCG on the expression of VHL, p53, and HIf2α were investigated. We demonstrate that in human granulosa lutein cells the tumor suppressor genes RB‐1, VHL, NF‐1, NF‐2, Wt‐1, p53, and APC and the hypoxia dependent transcription factors HIF‐1α, ‐2α, and ‐3α are expressed. In addition, we showed that hCG regulates the expression of p53, VHL, and HIF‐2α. Our results indicate that hCG may determine the growth and development of the corpus luteum by mediating hypoxic and apoptotic pathways in human granulosa lutein cells. Mol. Reprod. Dev. 69: 397–401, 2004. © 2004 Wiley‐Liss, Inc.
Protein synthesis and mRNA storage in cattle oocytes maintained under meiotic block by roscovitine inhibition of MPF activity
Authors: Vigneron Céline , Perreau Christine , Dalbiès‐Tran Rozenn , Joly Catherine , Humblot Patrice , Uzbekova Svetlana , Mermillod Pascal 
Published: September 2004

AbstractRoscovitine, a specific inhibitor of MPF kinase activity, has been shown to block efficiently and reversibly the meiotic resumption of oocytes from different species, including cattle. In view to verify that oocytes maintain germinal vesicle like molecular activities under roscovitine treatment, we compared in the present study the M‐phase Promoting Factor (MPF) and Mitogen Activated Protein (MAP) kinase activities; protein synthesis and phosphorylation patterns in oocytes and cumulus cells; and CDK1 and Cyclin B messengers storage under control culture and under roscovitine inhibition. We observed that roscovitine induced a full and reversible inhibition of MPF kinase activity and of the activating phosphorylation of both ERK1/2 MAPK. During in vivo maturation, there was a highly significant increase in the relative mRNA level of both cyclin B1 and CDK1 whereas during in vitro culture, the relative amount of CDK1 messenger was reduced. These messengers may be used as markers for the optimization of in vitro maturation treatment. Roscovitine reversibly prevented this drop in relative quantities of CDK1 messenger. Oocytes cultured in the presence of roscovitine maintained a GV like profile of protein synthesis except that two proteins of 48 and 64 kDa specific of matured oocytes also appeared under roscovitine treatment. However, roscovitine did not prevent most of the modifications of protein phosphorylation pattern observed during maturation. In conclusion, results of this study revealed that the use of roscovitine did not prevent all the events related to maturation of bovine oocytes. Mol. Reprod. Dev. 69: 457–465, 2004. © 2004 Wiley‐Liss, Inc.
A cyclic adenosine 3′,5′‐monophosphate‐induced tyrosine phosphorylation of syk protein tyrosine kinase in the flagella of boar spermatozoa
Authors: Harayama Hiroshi , Muroga Mai , Miyake Masashi 
Published: September 2004

AbstractA cyclic adenosine 3′,5′‐monophosphate (cAMP)‐dependent protein tyrosine phosphorylation is involved in the expression of fertilizing ability in mammalian spermatozoa. However, there are only limited data concerning the identification of protein tyrosine kinase (PTK) that is activated by the cAMP signaling. In this study, we have shown data supporting that boar sperm flagellum possesses a unique cAMP–protein kinase A (PKA) signaling cascade leading to phosphorylation of Syk PTK at the tyrosine residues of the activation loop. Ejaculated spermatozoa were washed and then incubated in a modified Krebs–Ringer HEPES medium (mKRH) containing polyvinyl alcohol (PVA) plus 0.1 mM cBiMPS (a cell‐permeable cAMP analog), 0.25 mM sodium orthovanadate (Na3VO4) (a protein tyrosine phosphatase (PTP) inhibitor) or both at 38.5°C for 180 min. Aliquots of the sperm suspensions were recovered before and after incubation and then used to detect sperm tyrosine‐phosphorylated proteins by Western blotting and indirect immunofluorescence. In the Western blotting, the anti‐phosphotyrosine monoclonal antibody (4G10) recognized several bands including 72‐kDa protein in the protein extracts from spermatozoa that were incubated solely with cBiMPS. The tyrosine phosphorylation in these sperm proteins was dependent on cBiMPS and enhanced by the addition of Na3VO4. The 72‐kDa tyrosine‐phosphorylated protein was apparently reacted with the anti‐phospho‐Syk antibody (Tyr525/526). Indirect immunofluorescence revealed that the connecting and principal pieces of spermatozoa incubated with cBiMPS and Na3VO4 were stained with the anti‐phospho‐Syk antibody. However, the reactivity of the 72‐kDa protein with the anti‐phospho‐Syk antibody was reduced by the addition of H‐89 (a PKA inhibitor, 0.01–0.1 mM) to the sperm suspensions but not affected by the pretreatment of spermatozoa with BAPTA‐AM (an intracellular Ca2+ chelator, 0.1 mM). Fractionation of phosphorylated proteins from the spermatozoa with a detergent Nonidet P‐40 suggested that the 72‐kDa tyrosine‐phosphorylated protein might be a cytoskeletal component. Based on these findings, we have concluded that the cAMP–PKA signaling is linked to the Ca2+‐independent tyrosine phosphorylation of Syk in the connecting and principal pieces of boar spermatozoa. Mol. Reprod. Dev. 69: 436–447, 2004. © 2004 Wiley‐Liss, Inc.
Cytoplasmic localization during testicular biogenesis of the murine mRNA for Spam1 (PH‐20), a protein involved in acrosomal exocytosis
Authors: Morales Carlos R. , Badran Haitham , El‐Alfy Mohamed , Men Hongsheng , Zhang Hong , Martin‐Deleon Patricia A. 
Published: September 2004

AbstractThe Sperm Adhesion Molecule1 (SPAM1) is the most widely conserved sperm antigen with important roles in mammalian fertilization. Light and electron microscopy were used to localize, by in situ hybridization, the cellular and subcellular sites of Spam1 mRNA in the murine testis. Transcripts were first detected in step 3 round spermatids, gradually increased until step 8 and abruptly decreased between steps 9–11. They were predominantly localized near the ER and were not dispersed throughout the cytoplasm. Immunohistochemistry revealed that Spam1 is present on both the head and tail of sperm in the seminiferous tubules, and provided support for transcriptional regulation of its transcript. Immunocytochemistry confirmed the location of Spam1 on the tail of testicular sperm and demonstrated that it is localized to both the principal piece and the midpiece. Spam1 on epididymal sperm is localized to the midpiece of the tail and changes from a uniform distribution on the head in the caput to a regionalized pattern, first on the posterior and then on the anterior head, in caudal sperm. Spam1 on the surface of caudal sperm was shown to mediate the increase in acrosome reactions induced by the synergistic effects of HA and progesterone, as confirmed in sperm from the Rb(6.16) translocation‐bearing mice which are Spam1 mutants. The similar response of human and mouse sperm to these agonists of the acrosome reaction, underscores the usefulness of the mouse as a model to study physiological aspects of SPAM1 in humans where, unlike the mouse, it is the only sperm hyaluronidase. Mol. Reprod. Dev. 69: 475–482, 2004. © 2004 Wiley‐Liss, Inc.
Copolymerization of 3‐buten‐1‐ol and propylene with an isospecific zirconocene/methylaluminoxane catalyst
Authors: Hagihara Hideaki , Tsuchihara Kenji , Sugiyama Junichi , Takeuchi Kazuhiko , Shiono Takeshi 
Published: September 2004

AbstractThe copolymerization of propylene and 3‐buten‐1‐ol protected with alkylaluminum [trimethylaluminum (TMA) or triisobutylaluminum] was conducted with an isospecific zirconocene catalyst [rac‐dimethylsilylbis(1‐indenyl)zirconium dichloride], combined with methylaluminoxane as a cocatalyst, in the presence of additional TMA or H2 as the chain‐transfer reagent if necessary. The results indicated that end‐hydroxylated polypropylene was obtained in the presence of the chain‐transfer reagents because of the formation of dormant species after the insertion of the 3‐buten‐1‐ol‐based monomer followed by chain‐transfer reactions. The selectivity of the chain‐transfer reactions was influenced by the alkylaluminum protecting the comonomer and the catalyst structure. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5600–5607, 2004
Comparative study of 2‐amino and 3‐aminobenzoic acid copolymerization with aniline synthesis and copolymer properties
Authors: Salavagione Horacio J. , Acevedo Diego F. , Miras Maria C. , Motheo Artur J. , Barbero Cesar A. 
Published: September 2004

AbstractPolyanilines soluble in an aqueous basic medium were synthesised by copolymerization of aniline (ANI) with both 2 and 3‐aminobenzoic acids (ABA). Different composition copolymers were prepared by varying the ANI/ABA feed ratio. Poly(aniline‐co‐2‐aminobenzoic acid) (PANI2ABA) and poly(aniline‐co‐3‐aminobenzoic acid) (PANI3ABA) displayed differences in their properties, such as specific charge and fluorescence behavior because the reactivity of 2‐aminobenzoic (2ABA) and 3‐aminobenzoic (3ABA) acids are very different. The new materials were characterized by X‐ray photoelectron, Fourier transform infrared, and Raman spectroscopies. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5587–5599, 2004