bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nucleolar proteins and ultrastructure in bovine in vivo developed, in vitro produced, and parthenogenetic cleavage‐stage embryos
Authors: Laurincik J. , Schmoll F. , Mahabir E. , Schneider H. , Stojkovic M. , Zakhartchenko V. , Prelle K. , Hendrixen P.J.M. , Voss P.L.A.M. , Moeszlacher G.G. , Avery B. , Dieleman S.J. , Besenfelder U. , Müller M. , Ochs R.L. , Wolf E. , Schellander K. , Maddox‐Hyttel P. 
Published: March 2003

AbstractIn the present study, ribosomal RNA (rRNA) gene activation, monitored through nucleolus development, was studied by autoradiography following 3H‐uridine incubation, transmission electron microscopy, and immunofluorescence confocal laser scanning microscopy of key nucleolar proteins involved in rRNA transcription (topoisomerase I, upstream binding factor, and RNA polymerase I) and processing (fibrillarin, nucleolin, and nucleophosmin) in in vivo developed, in vitro produced, and parthenogenetic bovine embryos. In general, in vivo developed embryos displayed formation of fibrillo‐granular nucleoli during the 4th post‐fertilization cell cycle. During the previous stages of development, nucleolus precursor bodies (NPBs) were observed. However, on some occasions the initial steps of nucleolus formation were observed already at the 2‐ and 4‐cell stage in cases where such embryos were collected from superovulated animals together with later embryonic stages presenting nucleolar development and autoradiographic labeling. The in vitro produced embryos displayed very synchronous formation of fibrillo‐granular nucleoli and autoradiographic labeling during the 4th cell cycle. In vivo developed and in vitro produced embryos displayed allocation of nucleolar proteins to fibrillar and granular compartments of the developing nucleoli during the 4th cell cycle. The parthenogenetic embryos typically displayed formation of fibrillo‐ granular nucleoli during the 5th cell cycle and autoradiographic labeling was not observed until the morula stage. Moreover, the 1‐, 2‐, and 4‐cell parthenogenetic embryos practically lacked NPBs. On the other hand, parthenogenetic embryos displayed allocation of nucleoar proteins to nuclear entities during the 4th cell cycle. In conclusion, both in vivo developed and in vitro produced bovine embryos displayed activation of transcription and nucleolar development during the 4th cell cycle. However, in vivo developed embryos flushed together with later developmental stages displayed premature activation of these processes. Parthenogenetic bovine embryos, on the other hand, displayed a delayed activation. Mol. Reprod. Dev. 65: 73–85, 2003. © 2003 Wiley‐Liss, Inc.
Immunolocalization of multiple Gα subunits in mammalian spermatozoa and additional evidence for Gαs
Authors: Baxendale Rhona W. , Fraser Lynn R. 
Published: March 2003

AbstractLike somatic cells, mammalian spermatozoa appear to contain several different heterotrimeric G protein α‐subunits that could mediate specialized cell responses. However, the precise Gα subunits present, their subcellular location and their possible roles are still incompletely defined. In this study, using commercially available specific antibodies, we have shown by immunoblotting that Gαs is present in human and mouse sperm lysates. Immunolocalization using intact spermatozoa from both species revealed this protein to be in the acrosomal cap region and the flagellum, particularly the principal piece. Treatment of permeabilized mouse spermatozoa with cholera toxin led to enhanced ADP‐ribosylation of a protein the same size as Gαs, as well as an increase in cAMP, providing further proof for Gαs. Evidence for the presence and distinct localizations of Gαi2, Gαi3, Gαo, Gαq/11, and Gαolf was also obtained. Of particular interest was Gαi2 which, like Gαs, was present in the acrosomal cap region and flagellum, the same regions where stimulatory and inhibitory adenosine receptors are localized. These observations are consistent with our hypothesis that G proteins mediate adenosine receptor modulation of adenylyl cyclase, with consequent alterations in cAMP production, apparently crucial for the spermatozoon's acquisition and maintenance of fertilizing ability. Mol. Reprod. Dev. 65: 104–113, 2003. © 2003 Wiley‐Liss, Inc.
Nuclear envelope proteins and neuromuscular diseases
Authors: Östlund Cecilia , Worman Howard J. 
Published: March 2003

AbstractSeveral neuromuscular diseases are caused by mutations in emerin and A‐type lamins, proteins of the nuclear envelope. Emery–Dreifuss muscular dystrophy is caused by mutations in emerin (X‐linked) or A‐type lamins (autosomal dominant). Mutations in A‐type lamins also cause limb‐girdle muscular dystrophy type 1B, dilated cardiomyopathy with conduction defect, and Charcot–Marie–Tooth disorder type 2B1. They also cause partial lipodystrophy syndromes. The functions of emerin and A‐type lamins and the mechanisms of how mutations in these proteins cause tissue‐specific diseases are not well understood. The mutated proteins may cause structural damage to cells but may also affect processes such as gene regulation. This review gives an overview of this topic and describes recent advances in identification of disease‐causing mutations, studies of cells and tissues from subjects with these diseases, and animal and cell culture models. Muscle Nerve 27: 393–406, 2003
CBA/J mice infected with Trypanosoma cruzi: An experimental model for inflammatory myopathies
Authors: Andersson John , Englund Pernilla , Sunnemark Dan , Dahlstedt Anders , Westerblad Håkan , Nennesmo Inger , Örn Anders , Lundberg Ingrid E. 
Published: March 2003

AbstractIdiopathic inflammatory myopathies are inflammatory disorders of unknown origin, characterized by muscle weakness. The aim of our study was to establish and characterize an animal model for chronic inflammatory myopathy which would permit investigations of the role of T‐cells in chronic myositis as well as of the mechanisms for muscle weakness in chronic inflammatory muscle disorders. CBA/J mice were infected with the protozoan parasite Trypanosoma cruzi. Immunohistochemistry was used to characterize the distribution and composition of inflammatory infiltrates, and demonstrated a chronic focal inflammation comprised mainly of T‐cells and macrophages in infected mice. The inflammatory infiltrates were predominantly found in the endomysium and, to a lesser extent, in perivascular areas. CD8+ T‐cells were found to have invaded nonnecrotic muscle fibers. Degenerating muscle fibers were also found, as well as an increased number of central muscle nuclei. The murine model described in this article may be useful in studying certain aspects of idiopathic inflammatory myopathies such as the role of T‐cells in chronic muscle inflammation and chronic myocytotoxicity. Muscle Nerve 27:442–448, 2003
Cross‐bridge mechanisms of muscle weakness in multiple sclerosis
Authors: Garner Dena J.P. , Widrick Jeffrey J. 
Published: March 2003

AbstractVastus lateralis muscle biopsies were obtained from six individuals with multiple sclerosis (MS) having an Expanded Disability Status Score of 4.75 ± 0.28, and from six age‐ and gender‐matched individuals without MS. Biopsies from the MS group showed fewer fibers (31 ± 4 vs. 46 ± 4%) containing the type IIa myosin heavy chain (MHC) isoform exclusively. However, the percentage of fibers coexpressing type IIa and IIx MHC increased in direct proportion with MS disability status. The average unloaded shortening velocity of skinned fibers containing type I or IIa MHC did not differ between subject groups. Peak Ca2+‐activated force was 11–13% lower in fibers from the MS group due to atrophy (type I and IIa fibers) and reduced specific force (type I fibers). Increasing intracellular inorganic phosphate (0–30 mM) or hydrogen ion (pH 7.0–6.2) reduced Ca2+‐activated force in a manner that was independent of MS status. Thus, fibers from the MS group showed a subtle shift in fast MHC isoform coexpression and a modest reduction in cross‐bridge number, density, or average force, with no change in maximal cross‐bridge cycling rate or susceptibility to intracellular metabolites. These changes explain part of the muscle weakness and fatigue experienced by individuals with MS. Muscle Nerve 27: 456–464, 2003
Diagnostic value of nerve biopsy for atypical chronic inflammatory demyelinating polyneuropathy: Evaluation of eight cases
Authors: Vallat Jean‐Michel , Tabaraud François , Magy Laurent , Torny Frédéric , Bernet‐Bernady Patricia , Macian Francisco , Couratier Philippe 
Published: March 2003

AbstractThe diagnosis of chronic inflammatory demyelinating polyneuropathy (CIDP) relies primarily on clinical and electrophysiologic examination, but the nerve biopsy findings may be supportive, especially in atypical cases. In order to define the usefulness of nerve biopsy in this disease, we retrospectively studied 44 consecutive patients whom we classified as having CIDP on pathological grounds. We found that 8 of these 44 patients had pathological findings indicative of CIDP but did not meet any of the usually accepted electrophysiological criteria for its diagnosis. Among these eight patients, five responded favorably to conventional therapy. All of these eight patients had an electrophysiological pattern of generalized axonopathy with additional subtle findings suggestive of demyelination that prompted us to perform a nerve biopsy. Our data suggest that a significant number of patients with unrecognized CIDP are erroneously classified as having chronic idiopathic axonal polyneuropathy. CIDP should be suspected if the electrophysiological examination displays subtle abnormalities suggestive of demyelination, even in the presence of a prominent axonal pattern. Nerve biopsy in these patients may reveal abnormalities suggestive of CIDP and guide therapeutic options. Muscle Nerve 27: 478–485, 2003
Abnormal coupling of knee and hip moments during maximal exertions in persons with cerebral palsy
Authors: Thelen Darryl D. , Riewald Scott A. , Asakawa Deanna S. , Sanger Terence D. , Delp Scott L. 
Published: March 2003

AbstractThe motions of lower‐limb extension, adduction, and internal rotation are frequently coupled in persons with cerebral palsy (CP) and are commonly referred to as an extension synergy. However, the underlying joint moments that give rise to these coupled motions are not well understood. We hypothesized that maximal voluntary exertions in a direction of one component of a synergy (e.g., hip extension) would result in the concurrent presence of other components of the synergy in subjects with CP but not in control subjects. To test this hypothesis, we measured three‐dimensional moments about the hip and knee as nine subjects with spastic CP and six control subjects performed maximal isometric exertions of the hip and knee flexors and extensors. During maximal hip extension exertions, control subjects simultaneously generated a knee flexion moment, whereas CP subjects generated a knee extension moment (P < 0.05) and a larger hip internal rotation moment than did controls (P < 0.05). During maximal knee extension exertions, control subjects generated a hip flexion moment, whereas CP subjects generated a hip extension moment (P < 0.05). The patterns of joint moments generated by CP subjects are consistent with an extension synergy and may underlie the coupled motion patterns of the lower extremity in such persons. Muscle Nerve 27: 486–493, 2003
Relationship between the positive temperature coefficient of resistivity and dynamic rheological behavior for carbon black‐filled high‐density polyethylene
Authors: Zheng Qiang , Song Yihu , Wu Gang , Song Xubing 
Published: March 2003

AbstractStudies on the relationship between resistivity and dynamic rheological properties of carbon black‐filled high‐density polyethylene (CB/HDPE) composites were carried out. Change of resistivity ρ is associated with the dynamic modulus before the positive temperature coefficient/negative temperature coefficient (PTC/NTC) transition temperature. When the temperature approaches the melting point of HDPE, ρ increases rapidly with a decreasing modulus, corresponding to PTC transition. The resistivity‐dynamic viscoelasticity relationship in the PTC region can be divided into two parts in which the changes of ρ with storage modulus G′ and loss modulus G″ can be described by the scaling laws given by the critical storage modulus and loss modulus G′c and G″c; adjustable parameters ρ′1c, ρ′2c, ρ″1c and ρ″2c; and nonlinear exponents n and m, respectively. The accordance between the experimental data and the scaling functions of the dimensionless quantities (G′/G′c − 1) and (G″/G″c − 1) in the PTC transition region suggests that the ρ jump may be the result of a modulus‐induced percolation. G′c and G″c increase, but the four scaling resistivitis, ρ′1c, ρ′2c, ρ″1c, and ρ″2c, decrease with increasing CB concentration, implying that the microstructure change of the composites is the determinant factor for the PTC behavior and the resistivity‐dynamic modulus relationship. However, ρ′2c and ρ″2c exhibit no scaling dependence. It is suggested that a threshold concentration exists for the modulus of the composites on the basis of examining the plot of both G′c and G″c against CB concentration. The scaling laws G′ ∼ Φx and G″ ∼ Φy hold for the concentration dependence of the critical modulus when Φ > Φc and the estimated values of x and y are 1.10 ± 0.10 and 0.89 ± 0.29, respectively. The resistivity‐dynamic modulus can shift to form a master curve. The horizontal factors aG′ and aG″ and the vertical factors a′ and a″ are relevant to the concentration dependence of the dynamic modulus or PTC behavior. It is believed that the former would be involved in changing the mechanical microstructure formed by the complicated interaction of CB particle and polymer segments, and the latter would be involved in the overall changes of conducting a network during the PTC transition region. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 983–992, 2003
Dialdehyde starch‐crosslinked chitosan films and their antimicrobial effects
Authors: Tang Rupei , Du Yumin , Fan Lihong 
Published: March 2003

AbstractFor improved mechanical and water‐swelling properties of chitosan films, a series of transparent films were prepared with dialdehyde starch as a crosslinking agent. Fourier transform infrared and X‐ray analysis results demonstrated that the formation of Schiff's base disturbed the crystallization of chitosan. The mechanical properties and water‐swelling properties of the films were significantly improved. The best values of the tensile strength and breaking elongation were 113.1 MPa and 27.0%, respectively, when the dialdehyde starch content was 5%. All the crosslinked films still retained obvious antimicrobial effects toward S. aureus and E. coli, and they showed potential for biomedical applications. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 993–997, 2003
Smectic structures in electrochemically prepared poly(3,4‐ethylenedioxythiophene) films
Authors: Breiby Dag W. , Samuelsen Emil J. , Groenendaal L. “Bert” , Struth Bernd 
Published: March 2003

AbstractSub‐micrometer layers of electrochemically prepared methyl‐ and decyl‐substituted poly(3,4‐ethylenedioxythiophene) (PEDOT) carrying perchlorate counterions have been examined with grazing incidence X‐ray diffraction with synchrotron radiation. The materials were found to be partially crystalline, and the data could be ascribed to a model of sheets of π‐π stacked polymer chains with a smectic ordering of these sheets. An unsubstituted PEDOT sample with the polymeric polystyrenesulfonic acid as a counterion was also investigated and turned out to be essentially amorphous. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 945–952, 2003
Warpage prediction of optical media
Authors: Fan Bingfeng , Kazmer David O. , Bushko Wit C. , Theriault Richard P. , Poslinski Andrew J. 
Published: March 2003

AbstractThe warpage of injection–compression‐molded optical media, such as compact discs and digital video discs, due to asymmetric cooling during production is predicted. Thermally induced stress is calculated with a nonisothermal compressible flow simulation with a viscoelastic constitutive model. A finite element analysis is formulated with axisymmetric plate elements based on Kirchhoff thin‐plate theory to simulate the warpage of the disc due to the asymmetric thermal stress and gravity after demolding. Simulation results of warpage for compact‐disc‐recordable moldings are compared with experimental observations under different processing conditions, such as the melt temperature, mold temperature, and packing pressure, with an optical grade of polycarbonate. The comparison shows that the simulation well predicts the effects of various processing conditions. Both the simulation and experiment indicate that of the processing conditions, the mold temperature has the greatest effect on warpage. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 859–872, 2003
Miscibility and ferroelectric behavior in blends of poly(vinylidene fluoride/trifluoroethylene) and poly(vinyl acetate)
Authors: Tang Yiwen , Scheinbeim Jerry 
Published: March 2003

AbstractThe blend system containing a poly(vinylidene fluoride/trifluoroethylene) [P(VDF/TrFE)] copolymer (68/32 mol %) and poly(vinyl acetate) (PVAc) was miscible from the results of differential scanning calorimetry (DSC) studies that exhibit the presence of a single, composition‐dependent glass transition temperature (Tg) and a strong melting point depression for the semicrystalline P(VDF/TrFE) component. However, differences between the DSC and dielectric measurements, which showed a separate P(VDF/TrFE) Tg peak, suggests that the P(VDF/TrFE)/PVAc blends are actually partially miscible. Because of the lower dielectric constant of PVAc and the reduced sample crystallinity caused by the addition of PVAc, both the dielectric constant and the remanent polarization of the copolymer blends decrease with increasing PVAc content. The presence of a small amount of PVAc stabilized the anomalous ferroelectric behavior of ice–water‐quenched P(VDF/TrFE), and the blend portrayed normal polarization reversal behavior after adding only 1 wt % PVAc. The piezoelectric response suggests small changes with an increasing number of poling cycles. It is believed that PVAc affects the D‐E hysteresis behavior at the interface between crystalline and amorphous phases, although much work remains to be done to confirm this hypothesis. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 927–935, 2003
Flame retardancy and smoke suppression of magnesium hydroxide filled polyethylene
Authors: Kim Sangcheol 
Published: March 2003

AbstractIn this work, halogen‐free, flame‐retarded polyethylene was investigated to study the effect of inorganic fillers on the improvement of flame retardancy and the suppression of smoke density. Through analyses on the thermal stability and smoke density, it was found that the flame retardancy developed by magnesium hydroxide could effectively be increased by the additional incorporation of zinc borate and talc. Furthermore, a synergistic effect was observed when zinc borate and talc were incorporated together. This result was confirmed by the observation of fire performance with cone calorimetry. A morphological study supported the idea that the improvement in the flame retardancy and the suppression of smoke density was due to hard and compact charred layers formed by the interactions between polymer and inorganic fillers. The charred layers provided a good thermal and flame barrier. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 936–944, 2003
Crystallization and morphology of poly(vinylidene fluoride)/poly(3‐hydroxybutyrate) blends. I. Spherulitic morphology and growth by polarized microscopy
Authors: Liu Jieping , Jungnickel Bernd‐J. 
Published: March 2003

AbstractThe development of the poly(3‐hydroxybutyrate) (PHB) morphology in the presence of already existent poly(vinylidene fluoride) (PVDF) spherulites was studied by two‐stage solidification with two separate crystallization temperatures. PVDF formed irregular dendrites at lower temperatures and regular, banded spherulites at elevated temperatures. The transition temperature of the spherulitic morphology from dendrites to regular, banded spherulites increased with increasing PVDF content. A remarkable amount of PHB was included in the PVDF dendrites, whereas PHB was rejected into the remaining melt from the banded spherulites. When PVDF crystallized as banded spherulites, PHB could consequently crystallize only around them, if at all. In contrast, PHB crystallized with a common growth front, starting from a defined site in the interfibrillar regions of volume‐filling PVDF dendrites. It formed by itself dendritic spherulites that included a large number of PVDF spherulites. For blends with a PHB content of more than 80 wt %, for which the PVDF dendrites were not volume‐filling, PHB first formed regular spherulites. Their growth started from outside the PVDF dendrites but could later interpenetrate them, and this made their own morphology dendritic. These PHB spherulites melted stepwise because the lamellae inside the PVDF dendrites melted at a lower temperature than those from outside. This reflected the regularity of the two fractions of the lamellae because that of those inside the dendrites of PVDF was controlled by the intraspherulitic order of PVDF, whereas that from outside was only controlled by the temperature and the melt composition. The described morphologies developed without mutual nucleating efficiency of the components. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 873–882, 2003
Mapping of periglacial geomorphology using kite/balloon aerial photography
Authors: Boike Julia , Yoshikawa Kenji 
Published: March 2003

AbstractKite and balloon aerial photography is introduced as a remote‐sensing method for periglacial features and vegetation. High‐resolution aerial pictures obtained by this method from Alaskan study sites are used for geometric analysis of ice‐wedge networks, quantification of patterned ground, and mapping of water and vegetation. High‐resolution aerial photographs could be an important data set for monitoring changes in permafrost pattern, periglacial processes and vegetation over time and space. Copyright © 2003 John Wiley & Sons, Ltd.
The development of periglacial geomorphology: 1‐ up to 1965
Authors: French Hugh 
Published: March 2003

AbstractThe earliest observations upon cold, non‐glacial processes and phenomena were made in the eighteenth and nineteenth centuries by the European explorers of the vast sub‐arctic regions of North America and Eurasia. The initial beginnings of periglacial geomorphology can be traced to Lozinski and the participants of the XI International Geological Congress excursion to Spitzbergen in 1910–11. The real growth in periglacial geomorphology occurred in the two decades after the Second World War. By the mid‐1960s periglacial geomorphology was recognized as a descriptive branch of climatic geomorphology. There were two broad sub‐categories: (i) Pleistocene and Quaternary studies dealing largely with the mid‐latitudes, and (ii) present‐day process studies conducted in the sub‐arctic and arctic regions of North America and Scandinavia. Permafrost studies were being conducted in relative isolation in North America and the Soviet Union, not only to each other, but also to mainstream periglacial geomorphology. The merging of all these interests, and the development of quantitative, process‐oriented studies aimed at understanding periglacial landforms did not come about for several more decades. Copyright © 2003 John Wiley & Sons, Ltd.