bluuebunny/crossref_metadata_2025_split huggingface dataset:
Kinetics and mechanism of ligand exchange of coordinated cyanide in hexacyanoferrate(II) by nitroso‐R‐salt in the presence of mercury(II) as a catalyst
Authors: Naik R. M. , Sarkar Joy , Chaturvedi D. D. 
Published: February 2005

AbstractThe kinetics of Hg(II)‐catalyzed reaction between hexacyanoferrate(II) and nitroso‐R‐salt has been followed spectrophotometrically by monitoring the increase in absorbance at 720 nm, the λmax of green complex, [Fe(CN)5 N‐R‐salt]3− as a function of pH, ionic strength, temperature, concentration of reactants, and the catalyst. In this reaction, the coordinated cyanide ion in hexacyanoferrate(II) gets replaced by incoming N‐R‐salt under the following specified reaction conditions: temperature = 25 ± 0.1°C, pH = 6.5 ± 0.2, and I = 0.1 M (KNO3). The stoichiometry of the complex has been established as 1:1 by mole ratio method. The rate of catalyzed reaction is slow at low pH values and then increases with pH and attains a maximum value between 6.5 and 6.7. The rate finally falls again at higher pH values due to nonavailability of [H+] ions needed to regenerate the catalytic species. The rate of reaction increases initially with [N‐R‐salt] and attains a maximum value and then levels off at higher [N‐R‐salt]. The rate of reaction shows a variable order dependence in [Fe(CN)64−] ranging from unity at lower concentration to 0.1 at higher concentrations. The effect of [Hg2+] on the reaction rate shows a complex behavior and the same has been explained in detail. The activation parameters for the catalyzed reactions have been evaluated. A most plausible mechanistic scheme has been proposed based on the experimental observations. © 2005 Wiley Periodicals, Inc. Int J Chem Kinet 37: 222–232, 2005
Kinetics and mechanism of the C2H5O2 + NO reaction: A temperature and pressure dependence study using chemical ionization mass spectrometry
Authors: Bardwell Max W. , Bacak Asan , Raventós M. Teresa , Percival Carl J. , Sanchez‐Reyna Gabriela , Shallcross Dudley E. 
Published: February 2005

AbstractThe overall rate coefficient (k1) for the reaction of C2H5O2 + NO has been measured using the turbulent flow CIMS technique. The temperature dependence of the rate coefficient was investigated between 203 and 298 K. Across the temperature range, the experimentally determined rate coefficients showed good agreement with previous studies and were fitted using an Arrhenius type analysis to yield the expression k1 = (1.75) × 10−12 exp[(462 ± 19)/T] cm3 molecule−1 s−1. Experiments were carried out in the pressure range of 100–200 Torr within the stated temperature range, where the rate coefficients were shown to be invariant with pressure. The branching ratio of the reaction was also assessed as a function of temperature and was found to proceed 100 ± 5% via the C2H5O + NO2 reactive channel. This work represents the first temperature and pressure study over which the branching ratio has been studied. © 2005 Wiley Periodicals, Inc. Int J Chem Kinet 37: 253–260, 2005
Improved Adhesion of UV Treated EVA Copolymer by Adding Small Amounts of Fillers
Authors: Landete‐Ruiz María Dolores , Martín‐Martínez José Miguel 
Published: February 2005

AbstractThe influence of adding small amounts of calcium carbonate or sepiolite fillers on the adhesion properties of UV surface‐treated ethylene vinyl acetate copolymer (EVA) was studied. In this paper, it has been demonstrated that the addition of 3‐7 wt% filler enhanced the extent of the surface modifications (wettability, surface chemistry, roughness) and increased the adhesion of EVA. These effects were more marked when 7 wt% sepiolite filler was added to EVA, likely due to its higher aspect ratio.
Effect of Unmodified and Surface Treated Fumed Silica on the Polymerization of HEMA
Authors: Tertykh Valentin , Bolbukh Yulia , Yanishpolskii Victor 
Published: February 2005

AbstractThermal polymerization of 2‐hydroxyethylmethacrylate (HEMA) and radical polymerization initiated by an acrylamid complex of cobalt nitrate in the presence of unmodified and surface treated silicas have been investigated. It has been found that the introduction of fillers, especially silicas with grafted silicon hydride groups, makes an essential effect on the rate and degree of the HEMA polymerization.
The Effect of Glass Fibre and a Phosphorus‐Containing Flame Retardant on the Flammability of Recycled PET
Authors: Maspoch Maria Lluïsa , Ferrando Haritz E. , Vega Diego , Gordillo Antonio , Velasco José Ignacio , Martínez Antonio B. 
Published: February 2005

AbstractThe availability of scrap poly(ethylene terephthalate) (PET) from post‐consumer bottles is increasing as the post‐consumer collecting systems are becoming more usual in daily life. PET is well known as a high‐performance engineering thermoplastic because of its good thermal stability, chemical resistance, and excellent mechanical properties. Many efforts have been carried out to use this material in housings of electronic applications. However, the flammability of PET is a shortcoming in some of these applications.In this study, our attempt is to incorporate a non‐halogenated flame retardant, in form of a phosphorus‐containing compound, together with a commercial glass fibre grade to achieve UL94 test V‐0 rating for PET. An investigation of thermal stability and flammability (HDT, UL94 V‐test) and mechanical (tensile, flexural and impact tests) properties of glass fibre filled PET samples is reported as a function of fraction of flame retardant.This work shows the influence of the filler content and the interfacial filler/matrix adhesion on the flame retardant and the mechanical properties.
Reply: Levodopa in the treatment of Parkinson's disease: Current controversies
Authors: Olanow C. Warren , Agid Yves , Mizuno Yoshi 
Published: February 2005

AbstractThe original articles to which this Letter refers have published in Movement Disorders: Current Controversies: Levodopa in the Treatment of Parkinson's Disease, by Sharma, Vassallo, and Ross and Levodopa in the Treatment of Parkinson's Disease: Current Controversies, by Gerlach, Reichmann, and Riederer.
Current controversies: Levodopa in the treatment of Parkinson's disease
Authors: Sharma Jagdish C. , Vassallo M. , Ross I.N. 
Published: February 2005

AbstractCompanion letters have been published in Movement Disorders: Levodopa in the Treatment of Parkinson's Disease: Current Controversies, by Gerlach, Reichmann, and Riederer and Reply: Levodopa in the Treatment of Parkinson's Disease, by Olanow, Agid, and Mizuno.
Microtubule formation from maternal tubulins during sea urchin embryogenesis: Measurement of soluble and insoluble tubulin pools
Authors: Gong Zhiyuan , Brandhorst Bruce P. 
Published: February 2005

AbstractThe mass of tubulin protein in developing embryos of the sea urchin Lytechinus pictus was measured using a radiodilution immunoassay based on densitometric analysis of immunoprecipitated tubulins resolved electrophoretically. The tubulins constitute an average of 360 ± 35 pg per egg, or 0.66% of the total protein, and there is no significant change in their concentration during embryogenesis. The masses of soluble and polymerized tubulins were measured for extracts prepared under conditions that stabilize microtubules. In eggs, a maximum of 14% of the tubulin is insoluble, and this increases throughout embryogenesis to 67% at pluteus stage (72 hr). The concentration of tubulin in eggs is at least 500 μg/ml, well above the critical concentration for tubulin assembly in vitro, yet microtubules have not been observed in eggs. The mass of newly synthesized tubulin, estimated from the mass of tubulin mRNA per embryo, accounts for a small fraction of the total tubulin by the end of gastrulation but for over half of the tubulin by the 72‐hr pluteus stage. These observations are consistent with a model in which the declining level of unpolymerized tubulin controls the stability of tubulin mRNA, providing an autogenous regulation of the ontogenetic pattern of tubulin synthesis during sea urchin embryogenesis (Gong and Brandhorst, Development 102: 31–43).
Identification of specific gene sequences in preimplantation embryos by genomic amplification: Detection of a transgene
Authors: King Donna , Wall Robert J. 
Published: February 2005

AbstractEndogenous and foreign DNA sequences can be detected in an extremely small number of cells via sequence amplification in vitro. The polymerase chain reaction (PCR) technique applied in multiple cycles allows the amplification of specific short regions of the genome to levels that can be detected by DNA blotting techniques. Cow and mouse blastocysts were analyzed by PCR for the presence of an endogenous single copy gene or an integrated foreign gene. The endogenous single‐copy gene encoding the β chain of bovine luteinizing hormone was detectable in cow blastocysts and in purified bovine genomic DNA representing as few as 25 cells. To determine whether exogenous genes (transgenes) can be detected in preimplantation embryos, transgenic male mice hemizygous for the prokaryotic gene encoding neomycin resistance where bred to nontransgenic females, and the resulting blastocysts were analyzed. The neo gene was detected in approximately half of the embryos. The capability to identify specific gene sequences in a limited number of embryonic cells affords investigators the opportunify to study genetics in early development.
Nucleologenesis and the onset of transcription in the eight‐cell bovine embryo: Fine‐structural autoradiographic study
Authors: Kopečný V. , Fléchon J. E. , Camous Sylvaine , Fulka J. 
Published: February 2005

AbstractEight‐cell cow embryos were isolated and cultured in vitro in a medium enriched with 200 μCi of [5‐3H]uridine for 20 min. Epon ultrathin sections of the embryos were investigated for the nucleolar morphology and for the appearance and localization of the sites of [5‐3H]uridine incorporation by means of electron microscopic autoradiography. In addition to this, a general pattern of replicated embryonal DNA distribution was revealed by [methyl‐3H]thymidine incorporation and light microscopic autoradiography.The essential phases of the transformation of the small nucleous precursor body (NPB) into a vast, functionally fully active nucleolus, characterized by typical nucleolar substructural components, are taking place within the eight‐cell stage. This process differed in its morphology from the nucleologenetic process in early embryogenesis of other mammals, especially of that in the mouse.The first sign of NPB, transformation was the appearance of a large central vacuole followed later on by perinucleolar chromatin penetration into NPB, documented by both morphology and [3H]thymidine autoradiography. In some cases, concentration of dense fibrillar material forming clumps or stalks was seen in the central vacuole.The following rapid nucleolar development was characterized by the formation of secondary vacuoles concomitant with the onset of [5‐3H]uridine incorporation into the dense fibrillar component and with the appearance of the first granules in the otherwise fibrillar structure of the nucleolus. During the late eight‐cell stage, the still‐rounded nucleolus developed features of a reticulated nucleolus known from somatic cells intensively synthesizing rRNA: a dense fibrillar component with associated labeling encircling fibrillar centers and a well‐developed granular component. The labeled dense fibrillar component was observed mostly in the central area of the nucleolus; early embryonic NPB dense fibrous material not involved in transcription was disappearing rapidly. At the transition to the 16‐cell stage the nucleoli lost their rounded shape because of the accumulation of a large amount of granular component, and they occupied a considerable part of the nucleus. In conclusion, the appearance of the nucleolar vacuole in eight‐cell cow embryo is the starting point for following morphogenetic events linked with the onset of transcription.
Posttranscriptional control of human homeobox gene expression in induced NTERA‐2 embryonal carcinoma cells
Authors: Simeone Antonio , Acampora Dario , D'Esposito Maurizio , Faiella Antonio , Pannese Maria , Scotto Luigi , Montanucci Manuela , D'Alessandro Gaetana , Mavilio Fulvio , Boncinelli Edoardo 
Published: February 2005

AbstractWe have studied the expression of four human homeobox genes representative of four different clusters (i.e., HOX‐1, HOX‐2, HOX‐3 and HOX‐5) in the embryonal carcinoma (EC) cell line NT2/D1. Following treatment with retinoic acid (RA), these cells differentiate into several cell types, including neurons, and steadily accumulate polyadenylated transcripts derived from the genes in a period ranging from 18 hr to 14 days of RA treatment. The sizes of major transcripts in differentiated EC cells coincide with those previously detected by the same probes in human embryos. Nuclear run‐on transcriptional analysis showed no difference in the transcription rate of the four homeobox genes in differentiated vs. undifferentiated EC cells. Inhibition of protein synthesis by 5–18 hr of treatment of undifferentiated cells with cycloeximide causes accumulation of some homeobox transcripts at levels comparable to those observed after 18 hr of RA induction, although it does not cause superinduction in fully differentiated cells. These data suggest that the activation of homeobox gene expression in RA‐induced EC cells is controlled, at least in part, by posttranscriptional mechanisms.
Production of transgenic sheep with growth‐regulating genes
Authors: Rexroad Caird E. , Hammer Robert E. , Bolt Douglas J. , Mayo Kelly E. , Frohman Lawrence A. , Palmiter Richard D. , Brinster Ralph L. 
Published: February 2005

AbstractPronuclei of fertilized sheep ova were injected with fusion genes consisting of the mouse metallothionein‐I promotor/regulator ligated to either the structural gene for bovine growth hormone (mMTbGH) or to a minigene for human growth hormone‐releasing factor (mMThGRF). From a total of 842 sheep ova injected with mMTbGH and transferred into recipient ewes, 47 lambs were born. Two of the lambs were transgenic with mMTbGH, and both had bGH mRNA present in liver, kidney, and gut. In one lamb, plasma growth hormone was as high as 700 ng/ml. From a total of 435 sheep ova injected with mMThGRF and transferred to recipients, 54 lambs were born and 9 fetuses were collected. Nine of the 63 had integrated the mMThGRF gene. One of the nine had high concentrations of immunoassayable hGRF in its plasma and high variable plasma concentrations of ovine growth hormone. The lamb that expressed the hGRF gene did not release GH in response to an hGRF challenge. Four of five fetal offspring of a nonexpressing mMThGRF transgenic ram also contained the mMThGRF gene and, like the sire, failed to express the gene as determined by either liver hGRF mRNA or by plasma hGRF. Growth of the single transgenic lamb expressing hGRF was similar to control lambs. These studies demonstrate efficient introduction of genes into the sheep genome and indicate that transgenes are expressed and heritable.
DNA sequence and pattern of expression of the sea urchin (Paracentrotus lividus) α‐tubulin genes
Authors: Gianguzza F. , Bernardo M. G. Di , Sollazzo M. , Palla F. , Ciaccio M. , Carra E. , Spinelli G. 
Published: February 2005

AbstractTo study the molecular aspects of the regulation of transcription of a multigene family, we have isolated and sequenced cDNA and genomic clones coding for the α‐tubulin of the sea urchin Paracentrotus lividus. Two cDNA clones, Pα 10 and Pα 4, contain respectively the coding information for 391 C‐terminal and for 338 N‐terminal amino acids of the 452 residues that constitute the complete protein. They show silent nucleotide substitutions only, suggesting that Pα 10 and Pα 4 represent the cloned copies of two allelic gene transcripts, which encode for two α‐tubulin isoforms with identical amino acid sequence in the region of the overlap. The comparison of the predicted amino acid sequence of the composite Pα 4–10 and of the mouse M α‐6 (Villasante et al., Mol. Cell Biol 1986; 6:2409–2419) reveals a conservation of 97% between the two polypeptides. By RNA blotting hybridization six major α‐tubulin transcripts were identified. Two, of 3.5 kb and 2.0 kb, are expressed in the unfertilized eggs and during early cleavage. The other two maternal mRNAs, of 2.4 kb and 1.8 kb, are expressed in both early and late cleavage embryos, but in the intestine the 1.8 kb RNA, which specifically reacted with the 3′ specific probe of the Pα 10 cDNA, is the only transcript detected. Finally, the 1.5 kb and 1.9 kb mRNAs represent the transcription of stage‐ and tissue‐specific genes, respectively. In fact, the former becomes detectable at blastula stage and accumulates during late development, whereas the latter is found in the testis only. The sequence data of the 3′ terminus of the α‐3 genomic clone suggests that it encodes for a divergent α‐tubulin, and it most probably corresponds to the testis‐specific gene.
Mouse transition protein 1 is translationally regulated during the postmeiotic stages of spermatogenesis
Authors: Yelick Pamela C. , Kwon Yunhee Kim , Flynn James F. , Borzorgzadeh Adel , Kleene Kenneth C. , Hecht Norman B. 
Published: February 2005

AbstractTransition protein 1 (TP1) is a small basic nuclear protein that functions in chromatin condensation during spermatogenesis in mammals. Here, recently identified cDNA clones encoding mouse transition protein 1(mTP1) were used to characterize the expression of the mTP1 mRNA during spermatogenesis. Southern blot analysis demonstrates that there is a single copy of the gene for transition protein 1 in the mouse genome. Northern blot analysis demonstrates that mTP1 mRNA is a polyadenylated mRNA approximately 600 bases long, which is first detected at the round spermatid stage of spermatogenesis. mTP1 mRNA is not detectable in poly(A)+ RNAs isolated from mouse brain, kidney, liver, or thigh muscle. mTP1 mRNA is translationally regulated in that it is first detected in round spermatids, but no protein product is detectable until approximately 3 days later in elongating spermatids. In total cellular RNA isolated from stages in which mTP1 is synthesized, the mTP1 mRNA is present as a heterogeneous class of mRNAs that vary in size from about 480 to 600 bases. The shortened, heterogeneous mTP1 mRNAs are found in the polysome region of sucrose gradients, while the longer, more homogeneous mTP1 mRNAs are present in the postmonosomal fractions.
Histone gene expression during sea urchin spermatogenesis: An in situ hybridization study
Authors: Poccia Dominic , Lieber Toby , Childs Geoffrey 
Published: February 2005

AbstractThe expression of testis‐specific and adult somatic histone genes in sea urchin testis was investigated by in situ hybridization. The testis‐specific histone genes (Sp H2B‐1 of Strongylocentrotus purpuratus and Sp H2B‐2 of Lytechinus pictus) were expressed exclusively in a subset of male germ line cells. These cells are morphologically identical to replicating cells pulse‐labeled with 3H‐thymidine. Genes coding for histones expressed in adult somatic and late embryo cells (H2A‐β for S. purpuratus and H3‐1 for L. Pictus) were expressed in the same germ line cells, as well as in the supportive cells (nutritive phagocytes) of the gonad. All histone mRNAs detected in the male germ lineage declined precipitously by the early spermatid stage, before cytoplasmic reduction. The data suggest that both testis‐specific and adult somatic histone genes are expressed in proliferating male germ line cells. Testis‐specific gene expression is restricted to spermatogonia and premeiotic spermatid, but somatic histone expression is not. The decline of histone mRNA in nondividing spermatids is not merely a consequence of cytoplasmic shedding, but probably reflects mRNA turnover.
Transgenic offspring by transcaryotic implantation of transgenic ovaries into normal mice
Authors: Brem Gottfried , Baunack Eva , Müller Mathias , Winnacker Ernst‐Ludwig 
Published: February 2005

AbstractFemale transgenic mice may be unable to reproduce successfully if the product encoded by the transgene results in pathological changes or affects the fertility of the mouse. To approach this problem, we have produced chimaeras by transferring the ovaries of transgenic mice into normal mice of the same strain. Such chimaeras will be an ideal tool for investigating the interactions between transgenic ovaries and normal mice or vice versa. Here we show that, using this method, we were able to get large numbers of transgenic offspring even from founder transgenic female mice that were themselves infertile as a result of the overexpression of growth hormone genes. Although none of the ovary recipients were given immunosuppressant treatment, 60% of the recipients had biologically active ovaries over a mean period of about 100 days.
Proacrosin activation and acrosin release during the guinea pig acrosome reaction
Authors: Nuzzo Nancy A. , Anderson Robert A. , Zaneveld Lourens J. D. 
Published: February 2005

AbstractThe kinetics of proacrosin activation and release from guine pig spermatozoa during the nonsynchronous acrosome reaction were studied. Epididymal spermatozoa were incubated at 37°C in a defined medium (pH 7.8) containing 1.7 mM Ca2+. After 195 min, 78% of the motile spermatozoa had undergone the acrosome reaction as determined by light microscopy. Acrosin and proacrosin levels in the spermatozoa and medium were measured at the beginning of the incubation period. Most of the total acrosin activity (78%) was associated with the spermatozoa, of which greater than 90% was in the form of proacrosin. Proacrosin represented a small, stable fraction (23%) of the total acrosin in the medium; it did not activate to acrosin while in the medium. After 195 min, a decrease in sperm‐associated total acrosin (42%; p < 0.05) was accompanied by an increase in the total acrosin level in the medium (115%; P < 0.05). No change in the relative proacrosin content (percent of total acrosin) was evident in either medium or spermatozoa. Additional experiments quantified acrosin and proacrosin during the progression of the acrosome reaction. Both the loss of sperm‐associated total acrosin and the increase in total acrosin levels in the medium were highly correlated with the fraction of acrosome‐reacted spermatozoa (r = 0.954 and 0.922, respectively; P < 0.001). However, the rate of acrosin appearance in the medium was only 60% (P < 0.001) of the rate of acrosin loss from the spermatozoa. The fractional proacrosin content of spermatozoa (94%) and medium (31%) remained unchanged during the acrosome reaction (r = 0.15 and 0.30, respectively; P > 0.1). From these data, it was possible to estimate the total acrosin content of acrosome‐intact spermatozoa (434 mlU/107 spermatozoa), and the fractions of the total sperm acrosin levels that are (1) released as active acrosin (37%), (2) released as proacrosin (17%), (3) inactivated (36%), and (4) associated with the spermatozoa (10%) during the acrosome reaction. The data suggest that proacrosin activation occurs within the spermatozoa, prior to distruption of the acrosome; this finding is consistent with the contention that acrosin is an active component of the mechanism underlying the acrosome reaction.