bluuebunny/crossref_metadata_2025_split huggingface dataset:
Inhibition of the human sperm acrosome reaction by proteinase inhibitors
Authors: De Jonge C. J. , Mack S. R. , Zaneveld L. J. D. 
Published: February 2005

AbstractThe analogue of the second messenger cAMP, dibutyryl cAMP (dbcAMP), was shown to induce the human sperm acrosome reaction to the same extent as calcium ionophore A23187, providing preliminary evidence for the involvement of the adenylate cydase system in the acrosome reaction (AR) of human spermatozoa. Using the human synchronous acrosome reaction system, proteinase inhibitors were tested for their effect on the dbcAMP‐induced human sperm acrosome reaction. The proteinase inhibitor 4′‐acctamidophenyl4‐guanidinoben‐zoate (AGB), an inhibitor of proacrosin activation and of acrosin, when added at either the onset of incubation or to capacitated spermatozoa, 5 min prior to stimulation by dbcAMP, significantly (P < 0.01) inhibited the acrosome reaction at final concentrations of 1 × 10−4 M to 1 × 10−6 M in comparison to dbcAMP treatment alone. At concentrations less than 1 × 10−6 M, no significant inhibitory effect was seen. Similarly, para‐aminobenzamidine (pAB), also an inhibitor of proacrosin activation and of acrosin, significantly (P < 0.01) inhibited the dbcAMP‐induced acrosome reaction at final concentrations of 1 × 10‐4 M to I × 10‐6 M when added at either the onset of incubation or to capacitated spermatozoa, 5 min prior to stimulation by dbcAMP, in comparison to stimulation by dbcAMP alone. However, at concentrations less than 1 × 10−6 M, no significant (P > 0.05) inhibitory effect was seen. These results indicate that a serine proteinase, most likely acrosin, has a role in the human sperm acrosome reaction and suggest that the enzyme functions after the involvement of the adenylate cyclase system.
Development in vitro of investment‐free marsupial embryos during cleavage and early blastocyst formation
Authors: Selwood Lynne 
Published: February 2005

AbstractTwenty embryos at the cleavage‐arrested four‐cell stage of the brown antechinus, Antechinus stuartii, were used to develop a method to obtain investment‐free embryos by incubation at 35°C in 2.5% pancreatin, 0.05% trypsin, and 0.05% pronase. Control intact embryos and the investment‐free embryos were incubated in Dulbccco's Modified Eagle's Medium with high glucose and 10% foetal calf serum in 5% CO2 in air at 35°C for 48 h. Release of embryos from the investments (shell, muooid, and zona pcllucida) took 4–4½ h in pancreatin, 6 h in trypsin, and 55 min to 1¼ h in pronase. Embryonic survival in vitro was best following pronase digestion. Pronase concentrations of 0.05%, 0.1 %, 0.25%, 0.5%, and 1.0% were used to free one‐to 16‐cell stage embryos of brown antechinus and the stripe‐faced dunnart, Sminthopsis macroura. from their investments. Postincubation survival and development of embryos in vitro was best using between 0.05% and 0.25% pronase. Blastomeres in both intact and investment‐free embryos shared similar characteristics during cleavage and blastocyst formation. The combined effect of these characteristics was that in intact embryos, no morula was formed, and the blastocyst developed, when cell numbers were high enough (about 32 cells), as a unilaminar structure flattened against the zona pellucida and without an inner cell mass. In investment‐free embryos, the blastomeres dispersed over the base of the culture vessel. The investments were necessary to confine the blastomeres, to provide a surface for blastomere flattening, and to allow normal cellular associations to develop.
Chemical N‐desulfation of heparin negates its ability to capacitate bovine spermatozoa
Authors: Milter David J. , Ax Roy L. 
Published: February 2005

AbstractHeparin specifically and saturably binds to bovine spermatozoa and stimulates capacitation as assessed by the ability of spermatozoa to undergo a zona pellucida‐induced acrosome reaction (AR) in vitro. However, the structural features of heparin important for capacitation are poorly understood The purpose of this study was to determine the importance of the sulfatc content of heparin for its potency to bind to bull spermatozoa and promote agglutination and capacitation. The pyridine salt of heparin was Nndesulfated, which reduced its mean sulfate content from 19.7% to 11.6%. The N‐desulfated heparin was then resulfated by incubation with trimcthylamine sulfur trioxide for 6,12, or 24 hr, raising sulfate to original concentrations. Heparin but not N‐desulfated beparin competed with [3H]‐heparin to bind to spermatozoa. Heparin at 11.6 μg/ml reduced [3H]‐heparin binding by half when competing with a saturating concentration of the radidabeled compound (12 μg/ml). N‐desulfated heparin did not displace [3H]‐heparin. Heparin, resulfated 6 hr or 12 hr, was equal to native heparin in binding potency. Heparin at 50,100, or 250 μg/ml caused more than 40% of the cells to head‐to‐head agglutinate in aggregates of 8 or more. N‐desulfated heparin did not cause agglutination. After spermatozoa were incubated with 0, 5,10, 50, 100, or 250 μg/ml of heparin for 4 hr, 100 μg/ml of lysophosphatidylcholine (LPC)‐induccd AR within 20 min in 21.3, 37.7, 27.8, 45.3, 54.2, or 42.5% of the cells, respectively. Sperm exposed to the same concentrations of N‐dcsulfated heparin exhibited AR of 17.7,27.3,24.3,22.5,27.7, or 33.8%, respectively, following exposure to LPG Resulfated heparin did not agglutinate or capacitate spermatozoa. In conclusion, N‐desulfation of heparin abolished heparin's ability to bind to, agglutinate, and capacitate bovine spermatozoa. Resulfation of N‐desulfated heparin restored binding activity but not agglutination or capacitation activity.
Blastocyst formation and hatching in vitro following zona drilling of mouse and human embryos
Authors: Malter Henry E. , Cohen Jacques 
Published: February 2005

AbstractHatching in vitro was studied following zona drilling of 507 two‐cell mouse embryos using three methods: 1) acidic Tyrode's (AT), 2) partial zona dissection (PZD) using a sharp micronecdle, and 3) zona chiseling (CH), using a large beveled needle. PZD and CH were performed while the embryos were kept in a sucrose/PBS solution. Hatching was compared to 191 umnicromanipulated controls. The incidences of cavitation and completion of hatching did not differ between groups, however more micromanipulated embryos (20–25%) hatched partially than controls (9%). The zona pellucida thinned in 59/59 (100%) control blastocysts during expansion, but in only 3/205 (2%) micromanipulated blastocysts. The hatching gap was wide in all control embryos, but smaller in 96/129 (75%) micromanipulated embryos. Partially hatched blastocysts with a ‘figure‐8’ shape were found in 59/129 (46%) micromanipulated embryos and in none of the 39 hatching controls. Hatching usually occurred a day earlier in micromanipulated embryos as 214/218 (98%) had started extruding on day 5 as compared to 20/59 (27%) control blastocysts. Fifty percent of 1‐day‐old human oocytes were fertilized following PZD and reinsemination and 15/31 (48%) were monospermic. Thirteen monospermic embryos cleaved, six compacted and four cavitatcd—of these, three extruded through the PZD incision upon expansion. The zonae did not thin and one blastocyst twinned spontaneously as it was caught between the thick ridges of the PZD hole. Results indicate that the hatching process is abnormal following zona drilling; more embryos start hatching, extrusion occurs earlier, and many become trapped which may lead to artificial twinning or the formation of trophoblastic vesicles.
Development of human male pronucleus: Ultrastructure and timing
Authors: Tesarik Jan , Kopecny Vaclav 
Published: February 2005

AbstractThe process of human male pronuclear formation was studied using an experimental model based on in vitro inseminated human zona‐free eggs prepared from oocytes that failed to fertilize in a clinical in vitro fertilization program. The main ultrastructural changes in penetrated sperm nuclei transforming into pronuclei were used to define four stages of pronuclear development. The first two stages, representing partial (Stage 1) and total (Stage 2) sperm chromatin decondensation, appeared as early as 1 hr after mixing of gametes. This rapid initial phase was followed by a more lengthy array of events leading to transformation of decondensed sperm nuclei into fully developed male pronuclei (Stages 3 and 4). Stage 3 was characterized by reformation of the nuclear envelope, reorganization of chromatin, and the assembly of nuclcolar precursors. It was not completed until 12 hr after in vitro insemination when fully developed male pronuclei (Stage 4) were first observed. In some eggs pronuclei did not reach Stage 4 at all. The results of this study provide a morphological background for further research into molecular aspects of human male pronuclear development and its regulation.
Production of bovine tetrapolid embryos by electrofusion and their developmental capability in vitro
Authors: Iwasaki S. , Kono T. , Fukastu H. , Nakahara T. 
Published: February 2005

AbstractOptimal conditions of electrofusion for blastomeres of two‐cell bovine embryos to produce tetraploid embryos were investigated. The high fusion rate (73–95%), viability, and develop mental capacity were obtained under a field strength of 1.0 kV/cm with direct current pulses of 10 or 25 μsec duration applied twice. Cytological study showed that 78.6% (11/14 embryos) of embryos exposed to electrofusion had tetraploid chromosome sets and the others were diploid or hexaploid. The tetraploid embryos had the capability to develop up to morulae stage in vitro.
Immunogold distribution of actin during sperimiogenesis in the normal rabbit and after experimental cryptorchidism
Authors: Fouquet Jean‐Pierre , Kann Marie‐Louise , Courtens Jean‐Luc , Ploöen Leif 
Published: February 2005

AbstractImmunogold procedures for actin detection were used in combination with experimental cryptorchidism in the rabbit as a modei to shed more light on the function of subacrosomal actin during spermiogenesis. In the normal testis, actin was localized in the perinuclcar substance (PNS) from round spermatid onward but it was not detected in late spermatids. Actin labeling in each type of spermatid was essentially unmodified after 24 hr of cryptorchidism. However, among relevant immediate and delayed effects, discontinuous acrosomes overlying a continuous PNS with normal actin labeling were noted. Nuclear invaginations were seen in combination with subacrosomal dilatations: at this site actin labeling was found only in the PNS closely apposed to the nuclear envelope. In subacrosomal areas lacking PNS, actin labeling also was lacking. These results suggest that the subacrosomal actin (F‐actin) is a component of the PNS that is tightly bound to the nuclear envelope rather than the overlying inner acrosomal membrane. Therefore, a function for the subacrosomal actin either in anchoring the acrosome to the nucleus or in capping the inner acrosomal membrane appears unlikely. The data rather suggest a capping function for the nuclear membrane during spermiogenesis.
Structural features of isolated generative cells and their protoplasts from pollen of some liliaceous plants
Authors: Tanaka Ichiro , Nakamura Sumio , Miki‐Hirosige Hisako 
Published: February 2005

AbstractLarge quantities of intact generative cells and their protoplasts were isolated from pollen protoplasts of four liliaceous plants, and their structural features were investigated. The generative cells, liberated from the vegetative cell cytoplasm of the pollen protoplasts, were initially spindle‐shaped with two long, oppositely oriented extensions, and were surrounded by two cell membranes, one on each side of a wall of uniform thickness. The generative nuclei, stained with 4′,6‐diamidino‐2‐phenylindole (DAPI), showed ellipsoidal and highly condensed chromatin, whereas the generative cell cytoplasm, whose quantity was widely different from species to species, showed no fluorescence, suggesting the absence of plastid and mitochondria! DNA, although many mitochondria were present. The isolated generative cells, which were spindle‐shaped at first, became spherical in shape in vitro. Immunocytochemistry and transmission electron microscopy revealed that this change was associated with the depolymerization of an axial array of microtubules present in generative cells in situ. These results are discussed in relation to the function of the generative cell within the bicellular pollen of angiosperms.
Devlopment of chimaeric two‐cell mouse embryos produced by allogenic exchange of single nucleus from two‐ and eight‐cell embryos
Authors: Kono Tomohireo , Tsunoda Yukio , Watanabe Tadao , Nakahara Tatsuo 
Published: February 2005

AbstractSynchronous or asynchronous chimaeras were produced by transplanting a single nucleus of two‐ and eight‐cell embryos from CD‐lxCD‐1 or BALB/CxBALB/C albino strains into one enucleated blastomere of a late Fl (C57/BLxCBA) × Fl two‐cell embryo. The cytoplasmic volume of the blastomere was reduced in some instances by 50%. These chimaeric embryos were cultured in vitro and transferred to pseudopregnant recipients. The distribution of each component to the pups and to the day‐10 embryos after transfer to recipients was determined by examining their coat color and by glucose phosphate isomerase analysis, respectively. The contribution of progeny of the nuclear‐transplanted cell with nonreduced cytoplast to the pups was 83% when synchronous; this proportion decreased to 43% when asynchronous because the progeny tended to migrate to the trophoblast and/or to the primitive endoderm. When the recipient cytoplast was reduced by 50%, the contribution of the nuclear‐transplanted cell progeny to the pups was 79% when synchronous and 80% when asynchronous. This shows that allogenic exchange of a single nucleus at the two‐cell stage by nuclear transfer is an effective procedure for producing highly asynchronous mouse chimaeras and suggests that larger and advanced blastomeres tend to be excluded from the inner cell mass of the embryo, but smaller, advanced blastomeres do not.
Development of a noninvasive ultramicrofluorometric method for measuring net uptake of glutamine by single preimplantation mouse embryos
Authors: Gardner D. K. , Clarke R. N. , Lechene C. P. , Biggers J. D. 
Published: February 2005

AbstractA noninvasive ultramicrofluorometric method for measuring net uptake of glutamine by single preimplantation mouse embryos is described. A linear relationship was found between fluorescence intensity of NADH produced and glutamine concentration (R2 = 0.985). Single embryos were placed in 20 nl drops of medium containing 0.5 mM glutamine, and the medium was sampled after 2 hr incubation at 37°C. Changes in net glutamine uptake were determined in one‐cell, two‐cell, and eight‐cell embryos and blastocysts incubated in medium containing no energy substrates (glucose, pyruvate, and lactate). The median glutamine uptake increased significantly from 0.480 and 0.270 pmoles/embryo/2 hr at the one‐cell and two‐cell stages, respectively, to 1.610 pmoles/embryo/2 hr at the blastocyst stage. Mean glutamine uptake was compared in the presence or absence of energy substrates at several developmental stages. A highly significant reduction of glutamine uptake in the presence of substrates was observed at the one‐cell and two‐cell stages of development. At the eight‐cell stage, glutamine uptake was only marginally reduced in the presence of substrates, and no effect was found at the blastocyst stage. These data may partially explain the beneficial effect of glutamine on the culture of early mouse embryos through the two‐cell block of development.
Changes in the rat sperm head during epididymal transit
Authors: Fornés Miguel W. , de Rosas Juan C. 
Published: February 2005

AbstractMorphological changes in sperm are one aspect of a maturation process during epididymal transit in marnrnals. The literature mentions only, for different strains of rats, a remodeling and decrease in size of the acrosome. In the present work, the sperm were obtained from caput, corpus, and cauda epididymis of the albino rat. Samples were processed for scanning electron microscopy, with routine techniques, and for light microscopy and video microscopy. It appeared, with these techniques, that the acrosomal curvature and the whole head surface area of the rat sperm decrease during the epididymal transit. To measure these changes, a geometrical method was designed, and surface measurements were made using a computer program. It was found that the caput sperm head has the greatest surface area and a sharper acrosome bend than the cauda sperm. In an attempt to explain the above‐mentioned changes, the suggestion is offered that some compactation of the nucleus and acrosomal material could be related to the decrease of the surface area.
Correlated errors in biased surrogates: study designs and methods for measurement error correction
Authors: Spiegelman D. , Zhao B. , Kim J. 
Published: February 2005

AbstractA measurement error model proposed previously allows for correlations between subject‐specific biases and between random within‐subject errors in the surrogates obtained from two modes of measurement. However, most of these model parameters are not identifiable from the standard validation study design, including, importantly, the attenuation factor needed to correct for bias in relative risk estimates due to measurement error. We propose validation study designs that permit estimation and inference for the attenuation factor and other parameters of interest when these correlations are present. We use an estimating equations framework to develop semi‐parametric estimators for these parameters, exploiting instrumental variables techniques. The methods are illustrated through application to data from the Nurses' Health Study and Health Professionals' Follow‐up Study, and comparisons are made to more restrictive models. Copyright © 2005 John Wiley & Sons, Ltd.
Methods for Fabricating Microarrays of Motile Bacteria
Authors: Rozhok Sergey , Shen Clifton K.‐F. , Littler Pey‐Lih H. , Fan Zhifang , Liu Chang , Mirkin Chad A. , Holz Richard C. 
Published: February 2005

AbstractMotile bacterial cell microarrays were fabricated by attaching Escherichia coli K‐12 cells onto predesigned 16‐mercaptohexadecanoic acid patterned microarrays, which were covalently functionalized with E. coli antibodies or poly‐L‐lysine. By utilizing 11‐mercaptoundecyl‐penta(ethylene glycol) or 11‐mercapto‐1‐undecanol as passivating molecules, nonspecific binding of E. coli was significantly reduced. Microcontact printing and dip‐pen nanolithography were used to prepare microarrays for bacterial adhesion, which was studied by optical fluorescence and atomic force microscopy. These data indicate that single motile E. coli can be attached to predesigned line or dot features and binding can occur via the cell body or the flagella of bacteria. Adherent bacteria are viable (remain alive and motile after adhesion to patterned surface features) for more than four hours. Individual motile bacterial cells can be placed onto predesigned surface features that are at least 1.3 μm in diameter or larger. The importance of controlling the adhesion of single bacterial cell to a surface is discussed with regard to biomotor design.
Accuracy of magnetic resonance imaging for measuring fetal sheep lungs and other organs
Authors: Jani J. , Breysem L. , Maes F. , Boulvain M. , Roubliova X. , Lewi L. , Vaast P. , Biard J.‐M. , Cannie M. , Deprest J. 
Published: February 2005

AbstractObjectiveLung volume measurement by fetal magnetic resonance imaging (fetMRI) has been used to predict survival of fetuses with isolated congenital diaphragmatic hernia (CDH). So far, the accuracy and precision of fetMRI for volumetry of either the normal or hypoplastic developing lung has not been formally studied.MethodsA total of nine sheep carrying 14 fetuses underwent fetMRI under general anesthesia at a mean of 118 days' gestational age (term = 145 days). A total of 61 organs were measured in nine normal fetal sheep and five that underwent surgical creation of diaphragmatic hernia (DH), so as to induce pulmonary hypoplasia. Lungs were measured on T2‐WI (weighted images) in three different planes, while liver and kidneys were measured in the axial (T1‐WI) and sagittal (T2‐WI) planes, respectively. Necropsy was done within 24 h after fetMRI to determine the volume postmortem by the water displacement method. Values were linearly correlated and a Bland and Altman analysis was done for volume measurement comparison, calculating means ± SD, bias (mean of the difference of volume measurements), precision (SD of the difference) and absolute and proportionate limits of agreement for both methods. The accuracy of fetMRI volume measurement was determined for different organ groups by calculating the median relative error and precision index, both being measures of error in proportion to the magnitude of the volume measured, as a clinically relevant proxy of potential errors.ResultsThe fetMRI volume measurements were on average larger than postmortem volumes, except for the kidneys. Kidney volume determination had a relative error of 29%, while measurements of larger organs had larger relative errors (42% for liver). Normal lungs were less accurately measured in the coronal or sagittal than in the axial plane (relative error 53%, 73% and 38%, respectively; P < 0.05 for sagittal vs. axial). Axially‐measured lung volumes were more accurate for lungs of normal sheep compared to DH lungs (relative error 38% vs. 73%, respectively; P < 0.05).ConclusionFetMRI measured systematically higher volumes for organs such as fetal liver or lung. This may be related to fluid loss or lack of perfusion at the time of necropsy. Measurement of lung volume by fetMRI was most accurate in the axial plane. Measurements of lung and liver volumes by fetMRI in normal sheep were both in agreement with volumes measured at necropsy. Loss of accuracy for DH‐lungs in comparison with the accuracy when measuring other similarly small organs, such as kidneys, suggests that fetMRI measurements can be less accurate for hypoplastic lungs related to CDH. With improving hardware, it might become easier to render the fetal lung and determine its volume reliably. Copyright © 2005 ISUOG. Published by John Wiley & Sons, Ltd.
Parallelization of divide-and-conquer in the Bird-Meertens formalism
Authors: Gorlatch Sergei , Lengauer Christian 
Published: February 2005

AbstractAn SPMD parallel implementation schema for divide-and-conquer specifications is proposed and derived by formal refinement (transformation) of the specification schema. The specification is in the form of a mutually recursive functional definition. In a first phase, a parallel functional program schema is constructed which consists of a communication tree and a functional program that is shared by all nodes of the tree. The fact that this phase proceeds by semantics-preserving transformations in the Bird-Meertens formalism of higher-order functions guarantees the correctness of the resulting functional implementation. A second phase yields an imperative distributed message-passing implementation of this schema. The derivation process is illustrated with an example: a two-dimensional numerical integration algorithm.