bluuebunny/crossref_metadata_2025_split huggingface dataset:
Methylprednisolone reduces the early vascular permeability increase in spinal nerve roots induced by epidural nucleus pulposus application
Authors: Byröd Gunnar , Otani Koji , Brisby Helena , Rydevik Björn , Olmarker Kjell 
Published: February 2005

AbstractAutologous nucleus pulposus is known to have injurious effects on spinal nerve roots when applied epidurally. Both inflammatory and immunological mechanisms have been implicated in this regard. Various proinflammatory substances might be released or activated by nucleus pulposus and might affect the endoneural nerve root vessels. The present study assessed nucleus pulposus‐induced early vascular reactions and the possibility of blocking these reactions with intravenous, high‐dose, methylprednisolone pretreatment. In 25 pigs, the S2 and S3 nerve roots were exposed. In five pigs (control group), retroperitoneal fat was applied epidurally on the nerve roots, and the other 20 pigs had nucleus pulposus applied. This group was subdivided into the treatment group (n = 8), in which the pigs were pretreated with intravenous high‐dose methylprednisolone (30 mg/kg body weight), and the nontreatment group (n = 12), in which the pigs received a corresponding volume of saline solution. After 2 hours, Evans blue labeled albumin was injected intravenously 5 minutes before death. Endoneural extravasation of Evans blue labeled albumin was evaluated with fluorescence microscopy. A marked albumin leakage was found in 67% of the nontreated animals, in 25% of those in the treatment group, and in none of the control animals. These results demonstrate that nucleus pulposus can induce a rapid increase in endoneural vascular permeability in spinal nerve roots after epidural application. This increase can be partially prevented by pretreatment with high‐dose methylprednisolone.
Kinetics and mechanism of the reaction of N‐chlorosuccinimide with I− and OH−
Authors: Agulla B. , Antelo J. M. , Arce F. , Parajó M. 
Published: February 2005

AbstractIn this kinetic study of the reaction between the iodide ion and the N‐chlorosuccinimide, we have found that the reaction is first order in N‐chlorosuccinimide: namely, first order with respect to the iodide ion and first order with respect to the proton concentration. Based on the experimental results, we propose a mechanism consistent in Cl+ transfer from the N‐chlorosuccinimide to the iodide ion. We have found that the reaction presents general acid catalysis with a Brönsted exponent value of 0.10. In addition, given that the N‐chlorocompounds are not stable in aqueous solution, we have carried out a study on the influence of bases in the presence of N‐chlorosuccinimide. We have found that the reaction is first order in hydroxide ion, as well as in the 1,1,1,3,3,3‐hexafluoroisopropanoxide ion and the 2,2,2‐trifluorethoxide ion, which shows that the reaction is general‐base catalyzed. © 2005 Wiley Periodicals, Inc. Int J Chem Kinet 37: 243–252, 2005
Synthesis of Large‐Area Three‐Dimensional Polyaniline Nanowire Networks Using a “Soft Template”
Authors: Zhong Wenbin , Deng Jianyuan , Yang Yongsheng , Yang Wantai 
Published: February 2005

AbstractSummary: Three‐dimensional polyaniline (PANI) nanowire networks were synthesized in high yield using a “soft template” self‐assembled with hexadecyltrimethylammonium bromide and oxalic acid. The PANI nanowire networks had diameters from 35–100 nm depending on synthesis conditions and/or procedures. The networks and the “cross‐linking points” were clearly observed by field‐emission scanning electron microscopy and transmission electron microscopy. A possible mechanism for the formation of three‐dimensional PANI nanowire networks is discussed.FESEM image of PANI with three‐dimensional nanowire networks.magnified imageFESEM image of PANI with three‐dimensional nanowire networks.
Electroactive Shape‐Memory Polyurethane Composites Incorporating Carbon Nanotubes
Authors: Cho Jae Whan , Kim Jeong Won , Jung Yong Chae , Goo Nam Seo 
Published: February 2005

AbstractSummary: Electro‐active shape‐memory composites were synthesized using conducting polyurethane (PU) composites and multi‐walled carbon nanotubes (MWNTs). Surface modification of the MWNTs (by acid treatment) improved the mechanical properties of the composites. The modulus and stress at 100% elongation increased with increasing surface‐modified MWNT content, while elongation at break decreased. MWNT surface modification also resulted in a decrease in the electrical conductivity of the composites, however, as the surface modified MWNT content increased the conductivity increased (an order of 10−3 S · cm−1 was obtained in samples with 5 wt.‐% modified‐MWNT content). Electro‐active shape recovery was observed for the surface‐modified MWNT composites with an energy conversion efficiency of 10.4%. Hence, PU‐MWNT composites may prove promising candidates for use as smart actuators.The electro‐active shape‐recovery behavior of PU‐MWNT composites. The pictured transition occurs within 10 s when a constant voltage of 40 V is applied.magnified imageThe electro‐active shape‐recovery behavior of PU‐MWNT composites. The pictured transition occurs within 10 s when a constant voltage of 40 V is applied.
Rubber Powder – A Perspective Filler of Thermoplastics
Authors: Wagenknecht Udo , Steglich Stefanie , Wiessner Sven , Michael Hannes 
Published: February 2005

AbstractRubber powder, ground at ambient temperature, was compounded with polypropylene using only 16 L/D of a co‐rotating twin screw extruder. An optimum of extruder configuration and selected process parameters were found for compounds with a rubber filling rate of 50 wt.‐%. Restrictions of a reactive compounding were taken into account. The dispersion of the rubber powder is not a limiting process. A compound containing 70 wt.‐% rubber powder showed to be overfilled.
Levodopa in the treatment of Parkinson's disease: Current controversies
Authors: Gerlach Manfred , Reichmann Heinz , Riederer Peter 
Published: February 2005

AbstractCompanion letters have been published in Movement Disorders: Current Controversies: Levodopa in the Treatment of Parkinson's Disease, by Sharma, Vassallo, and Ross and Reply: Levodopa in the Treatment of Parkinson's Disease, by Olanow, Agid, and Mizuno.
In vitro effects of growth factors on rat germ cell RNA synthesis and their modulation by sertoli cell‐secreted proteins
Authors: Fradin S. , Barbey P. , Drosdowsky M. A. 
Published: February 2005

AbstractIn vitro rat germ cell RNA synthesis is influenced by growth factors. Basic fibroblast growth factor (0.1 to 100 ng/ml) increases [3H]uridine incorporation in round spermatids (RS) but not in pachytene spermatocytes (PS); this effect is potentiated by insulin (10 μg/ml) and blocked in the presence of Sertoli cell‐secreted proteins (SCSP). Somatomedin C (0.1 to 100 ng/ml) exhibits a similar effect when used alone without an influence by SCSP. Transforming growth factor β (0.1 to 10 ng/ml) acts on both cell types, but SCSP amplify this effect only in PS. These data suggest that growth factors synthesized in situ may play a role in the germ cell development and that their effects are moduiated by SCSP.
Detection of Y‐bearing spermatozoa by DNA‐DNA in situ hybridisation
Authors: West John D. , West Katrine M. , Aitken R. John 
Published: February 2005

AbstractIn situ hybridisation of a Y chromosome‐specific DNA probe to preparations of decondensed spermatozoa revealed approximately 46.7% labelled spermatozoa among 3,900 scored. This is not significantly different from the 50% expected if only the Y chromosome‐bearing spermatozoa are hybridised. Control hybridisations of Escherichia coli DNA and salmon testis DNA to decondensed sperm produced no significant labelling, whereas more than 99% of the spermatozoa were heavily labelled after hybridisation to total human DNA. These controls indicate that the methodology described in this paper renders the chromatin accessible for hybridisation and that the 50% hybridisation observed with the Y chromosome DNA probe was specific. In situ hybridisation with the Y probe therefore identifies the Y‐bearing spermatozoa, and the protocol described should prove useful in evaluating methods of separating Y‐bearing and X‐bearing spermatozoa.
Influence of single amino acids on the development of hamster one‐cell embryos in vitro
Authors: Bavister Barry D. , Arlotto Theresa 
Published: February 2005

AbstractOne‐cell hamster embryos placed in culture have always shown a complete block to development at the two‐cell stage. In a preliminary study using a chemically defined culture medium containing 20 amino acids (HECM‐1), many one‐cell embryos were able to escape the “two‐cell block” and develop to the four‐cell stage. Use of a simpler formulation containing only the amino acids hypotaurine and glutamine revealed marked inhibitory and stimulatory effects of adding the other amino acids. In the first experiment, 19 amino acids were separately examined for effects on one‐cell embryo development. Six amino acids (phenylalanine, valine, isoleucine, tyrosine, tryptophan, and arginine) inhibited embryo development (reduced mean cell number; MCN), and three others (glycine, cystine, and lysine) stimulated development (increased MCN), compared with basic medium containing only glutamine and hypotaurine (low control). When the responses with the six inhibitory amino acids were totalled, only 3 of 185 (2%) one‐cell embryos reached the six‐or seven‐cell stage compared to a total of 15 of 76 (20%) embryos that developed to these stages using the three stimulatory amino acids. When tested together in a second experiment, the six inhibitory amino acids significantly reduced the MCN, from 4.28 ± 0.44 (low control) to 3.71 ± 0.55. In this group, 17 of 117 (15%) of one‐cell embryos reached more than four‐cell and only 4 of 117 (3%) reached six‐ or 7‐cell stages, compared with 39 of 117 (33%) and 12 of 117 (10%), respectively, for the basal medium group. The stimulatory (glycine, cystine, lysine) and “neutral” (cysteine‐SH, proline, serine, threonine, histidine, alanine, hydroxyproline, leucine, aspartic acid, methionine) groups did not significantly alter the MCN, but both supported development of a substantial proportion of one‐cell embryos to more than four‐cell stages (38% and 48%, respectively, of 126 embryos in each group), and to six‐ or seven‐cell stages (20% and 29%, respectively, for the stimulatory and neutral groups). In these two groups, a few one‐cell embryos even reached the eight‐cell or blastocyst stages. This study shows that the type of amino acid in the culture medium has a profound influence on the number of cleavage divisions undergone by one‐cell hamster embryos and suggests that, at least in vitro, amino acids may play an important regulatory role in early preimplantation development in this species.
Culture media for mouse oocyte maturation affect subsequent embryonic development
Authors: van de Sandt J. J. M. , Schroeder A. C. , Eppig J. J. 
Published: February 2005

AbstractThese experiments were done to determine whether the culture medium used for the spontaneous maturation of mouse oocytes can affect the subsequent capacity of the ova to become fertilized and complete preimplantation development in vitro and development to live young. Oocytes obtained from antral follicles of gonadotropin‐primed immature mice underwent spontaneous maturation in control medium, i.e. Eagle's Minimum Essential Medium (MEM) supplemented with 5% fetal bovine serum, or in one of eight different media which were also supplemented with serum. All of the ova were fertilized in Whitten's medium and were assessed for cleavage to the 2‐cell stage and for further preimplantation development to blastocysts during culture in Whitten's medium. Three of the eight media used for oocyte maturation improved the capacity of the ova to develop to the blastocyst stage when compared with the control: Waymouth MB 752/1, MEM with non‐essential amino acids, and MEM Alpha; Waymouth medium promoted the highest frequency of development of ova to the blastocyst stage. Moreover, the blastocysts derived from oocytes that matured in Waymouth medium contained more cells than blastocysts derived from oocytes that matured in control medium. Although BGJb medium promoted the cleavage of eggs to the 2‐cell stage when present during oocyte maturation, it had a detrimental effect on their subsequent preimplantation developmental capacity. Following transfer to foster mothers, more 2‐cell stage embryos developed to live young after oocyte maturation in Waymouth medium (21%) than in control medium (13%). It is concluded that the medium used for oocyte maturation in vitro can affect processes involved in the subsequent development of the eggs and that, of the media tested, Waymouth MB 752/1 promoted the highest capacity for embryo development of maturing mouse oocytes.
Evidence for an increased sensitivity to Ca2+ in the flagella of sperm from tw32/+ mice
Authors: Lindemann Charles B. , Goltz Jason S. , Kanous Kathleen S. , Gardner Tressa K. , Olds‐Clarke Patricia 
Published: February 2005

AbstractThe majority of sperm from mice carrying the tw32 haplotype undergo hyperactivation sooner than sperm from +/+ mice of the same strains (Olds‐Clarke, Dev Biol 131:475–482, 1989). To investigate the mechanism underlying this abnormal motility, the Ca2+ sensitivity of their flagellar apparatus was compared to that of age‐ and strain‐matched controls using Triton X‐100‐extracted sperm. Under these conditions, the curvature of the sperm flagellum is controlled by the free calcium concentration. Sperm from mice carrying the tw32 haplotype consistently exhibited a change in flagellar curvature at lower free calcium concentrations than controls. In addition, intact sperm from tw32/+ mice were much more likely than congenic control sperm to have a hook‐like bend in the midpiece, which persisted throughout most of the beat cycle. Sperm exhibiting the hooked middle piece could be converted to a more normal appearance by 2mM procaine, which immobilizes cytoplasmic calcium. Thus an increased sensitivity of the sperm motor apparatus to calcium could be the cause of the precocious hyperactivation of sperm from mice carrying the tw32 haplotype.
Effects of gonadotropins and granulosa cell secretions on the maturation and fertilization of rat oocytes in vitro
Authors: Vanderhyden B. C. , Armstrong D. T. 
Published: February 2005

AbstractFully grown germinal vesiclestage oocytes are induced to resume meiosis and acquire the capacity to undergo fertilization in response to a surge of gonadotropins. The present study examined possible direct and indirect roles of gonadotropins in the maturation and fertilization of rat oocytes by determining 1) the effect of exogenous administration of gonadotropins (priming) to immature rats prior to oocyte collection on the capacity of oocytes to undergo maturation and fertilization in vitro, 2) the effect of follicle‐stimulating hormone (FSH) in the maturation media on the resumption of meiosis and subsequent capacity of oocytes to undergo fertilization, and 3) the capacity of oocytes to undergo maturation and fertilization following culture in preovulatory follicular fluid or in conditioned media obtained from gonadotropin‐stimulated granulosa cell (GC) cultures. In the first experiment, oocytes from unprimed rats underwent spontaneous meiotic maturation in vitro and 17% underwent subsequent fertilization. Priming increased the proportion of oocytes undergoing fertilization. Maturation of oocytes in media supplemented with various concentrations of FSH or for various lengths of time (6–16 h) in medium with 500 ng FSH/ml indicated that FSH slowed the rate of meiotic maturation, but had no effect on the capacity of the oocytes to be fertilized. Oocytes obtained from primed animals and cultured in the presence of preovulatory follicular fluid were fertilized in proportions similar to those cultured in serum‐containing medium. In the third experiment, medium conditioned by FSH‐stimulated GC for 40 h slowed the rate of meiotic maturation; the addition of luteinizing hormone (LH) to the FSH‐stimulated cells produced a medium in which the rate of oocyte maturation was not different from that of control oocytes (in medium from unstimulated cells). Medium conditioned by FSH‐ or LH‐stimulated GC, but not fibroblasts, increased the proportions of oocytes undergoing fertilization following maturation in those media. FSH + LH stimulation of GC increased the fertilization of oocytes to proportions significantly higher than with either gonadotropin alone. These data suggest that GC respond to gonadotropin stimulation by providing a factor(s) that regulates the rate of oocyte maturation and promotes the capacity of oocytes to undergo fertilization.
In vitro fertilization of horse follicular oocytes matured in vitro
Authors: Zhang J. J. , Muzs L. Z. , Boyle M. S. 
Published: February 2005

AbstractIn vitro fertilizing ability of stallion spermatozoa was assessed using horse follicular oocytes matured in vitro. After collection, stallion spermatozoa were either: 1) washed and incubated in TALP medium with 3 mg/ml bovine serum albumin (BSA) and 10 μg/ml heparin for 4 h, 2) washed and incubated in TALP with 3 mg/ml BSA for 3 h and cultured for a further 1 h with 1 mM caffeine and 5 mM dbcAMP, 3) washed and incubated in TALP medium with 3 mg/ml BSA at pH 7.9–8.2 for 2–4 h, or 4) diluted and incubated in TALP medium with 10 mg/ml BSA and 7.14 μM calcium ionophore A 23187 for 5–10 min followed by washing. After a given pretreatment, suspensions were diluted into B2 medium to a concentration of 5 × 106 sperm/ml and co‐incubated with oocytes for 12 h or 24–48 h. In the ionophoretreated group, 18 of 54 oocytes (33%) were fertilized by 12 h, and 11 of 45 (24%) cleaved by 24–48 h. Evidence of fertilization was not found in the oocytes incubated with spermatozoa from other treatment procedures.
Changes in calmodulin compartmentalization throughout capacitation and acrosome reaction in guinea pig spermatozoa
Authors: Trejo Raquel , Mújica Adela 
Published: February 2005

AbstractCalmodulin has been postulated as a mediator in the calcium‐dependent processes that culminate in the acrosome reaction. Changes in calmodulin compartmentalization as a consequence of the increased permeability to extracellular calcium during capacitation and acrosome reaction have been suggested. In the present study the temporal localization of calmodulin in guinea pig spermatozoa was studied during in vitro capacitation and acrosome reaction by indirect immunofluorescence. Capacitation was achieved by incubation in Tyrode medium supplemented with pyruvate, lactate, and glucose in the presence and in the absence of calcium. Acrosome reaction was elicited in three different conditions: 1) by transfer to minimal culture medium containing pyruvate and lactate (MCM‐PL) after in vitro capacitation, 2) by 0.003% Triton‐X 100 treatment, and 3) by A 23187 addition to sperm samples incubated in MCM‐PL. During capacitation, calmodulin was observed both in the acrosome and in the flagellum; this localization seemed to be independent of the presence of extracellular calcium and of exogenous substrates. Throughout the acrosome reaction, different stages of calmodulin compartmentalization were observed. It became clustered around the equatorial region just before or a little after the acrosome reaction had occurred. Later, it was observed around the postacrosomal region in the acrosome‐reacted sperm. The changes in calmodulin distribution were found to be dependent on the stage in the acrosome reaction.
Acrosome reaction of stallion spermatozoa evaluated with monoclonal antibody and zona‐free hamster eggs
Authors: Zhang J. , Boyle M. S. , Smith C. A. , Moore H. D. M. 
Published: February 2005

AbstractThe acrosome of the stallion spermatozoon was visualized by indirect immunofluorescence with monoclonal antibody (18.6) which recognized an integral acrosomal membrane component. Localization was confirmed by electron microscopy using peroxidase labelled antibody. In fresh semen samples (n = 19), 73.9 ± 9.1% of the spermatozoa from five fertile stallions displayed a uniform bright fluorescence over their acrosome region. In two semen samples from an infertile stallion only 28% and 35% of spermatozoa showed the same pattern of fluorescence. Spermatozoa from fertile stallions incubated for up to 12 hours in TALP medium maintained motility and exhibited a significant progressive loss of acrosomes as detected by immunofluorescence. Alternatively, a similar loss of acrosomes could be induced with calcium ionophore A23187 over a 90 minute incubation. Ultrastructural observations and incubation with zona‐free hamster eggs indicated that only with ionophore treatment was immunofluorescent acrosome loss correlated with a physiological acrosome reaction, while prolonged sperm incubation led to degenerative membrane changes. It was concluded that, if carefully validated, immunofluorescent localization of the acrosome of stallion sperm with monoclonal antibody could be used to monitor the acrosome reaction. Furthermore, definitive acrosome visualization would be valuable in assessing semen quality.
Cell‐cycle aspects of growth and maturation of mammalian oocytes
Authors: Motlík Jan , Kubelka Michal 
Published: February 2005

AbstractIn this review, recent data concerning growth and maturation of nonmammalian and mammalian female germ cells are compiled with regard to the increased understanding of somatic cells mitotic cycles, from yeast to human tissues. These data allow us to conclude that growing oocytes of nonvertebrates, lower vertebrates, and mammals resemble somatic cells in the G1 phase of the mitotic cycle in their metabolic and cell cycle behavior. Transcriptional and translational activity of growing oocytes and G1 somatic cells is not compatible with the activation of maturation promoting factor (MPF), with chromatin condensation or with nuclear membrane disintegration. Growing oocytes, even when they are in the dictyate stage of the first meiotic division, promptly inactivate MPF introduced into their cytoplasm by fusion or microinjection, just as do somatic interphase cells.In mammals, the LH surge induces “de novo” RNA and protein synthesis in granulosa cells. This metabolic change in granulosa cells abolishes their inhibitory activity, and meiosis in fully grown oocytes in preovulatory follicles is then resumed. Resumption of meiosis requires an activation of pre MPF molecules within oocytes. This can be achieved either without (mouse, rat, and rabbit) or with (pig, sheep, and cow) an active protein synthesis by the oocytes. The species specificity is probably dependent on the presence or absence of cyclin‐like and/or mos‐like molecules in fully grown oocytes. Both major events during GVBD, chromatin condensation, and nuclear envelope disintegration require protein phosphorylation. Experimentally, these two phosphorylation activities can be separated one from another. The active MPF molecules are amplified autocatalytically in amphibian and starfish oocytes. However, an increase of MPF activity in mouse and pig oocytes, similarly as in Rana pipiens and sturgeon oocytes, requires an active protein synthesis.