bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of 6‐dimethylaminopurine on electrically activated in vitro matured porcine oocytes
Authors: Grupen Christopher G. , Mau James C. , McIlfatrick Stephen M. , Maddocks Simon , Nottle Mark B. 
Published: August 2002

AbstractThe effect of the protein kinase inhibitor, 6‐dimethylaminopurine (6‐DMAP), on the maturation promoting factor (MPF) activity, pronuclear formation, and parthenogenetic development of electrically activated in vitro matured (IVM) porcine oocytes was investigated. Oocytes were activated by exposure to two DC pulses, each of 1.5 kV/cm field strength and 60 μsec duration, applied 1 sec apart. In the first experiment, subsequent incubation with 2 or 5 mM 6‐DMAP for 3 hr increased the incidence of blastocyst formation compared with no treatment, whereas incubation with 2 or 5 mM 6‐DMAP for 5 hr did not. In the proceeding experiments, oocytes exposed to 6‐DMAP were incubated with 2 mM of the reagent for 3 hr. Assaying histone H1 kinase activity in the second experiment revealed that the levels of active MPF in electrically activated oocytes treated with 6‐DMAP were depleted more rapidly and remained depleted for longer compared with electrical activation alone. The kinetics of MPF activity following 6‐DMAP treatment were similar to that found in inseminated oocytes in the third experiment. The effect of 6‐DMAP was correlated with an increased incidence of parthenogenetic blastocyst formation. A fourth experiment was undertaken to examine the diploidizing effect of 6‐DMAP. Electrically activated oocytes treated with 6‐DMAP and cytochalasin B, either alone or in combination, displayed a higher incidence of second polar body retention compared with those that were untreated or treated with cycloheximide alone. After 6 days of culture in vitro, parthenotes exposed to 6‐DMAP, either alone or in combination with cytochalasin B, formed blastocysts at a greater rate compared with those exposed to cytochalasin B alone, cycloheximide alone or no treatment. The combined 6‐DMAP and cytochalasin B treatment induced the highest rate of blastocyst formation (47%), but the numbers of trophectoderm and total cells in these blastocysts were lower compared with those obtained following exposure to 6‐DMAP alone. These results suggest that the increased developmental potential of 6‐DMAP‐treated parthenotes may be attributable to the MPF‐inactivating effect of 6‐DMAP, rather than the diploidizing effect of 6‐DMAP. Mol. Reprod. Dev. 62: 387–396, 2002. © 2002 Wiley‐Liss, Inc.
Paternal influence on the time of first embryonic cleavage post insemination and the implications for subsequent bovine embryo development in vitro and fertility in vivo
Authors: Ward Fabian , Rizos Dimitrios , Corridan Doreen , Quinn Katherine , Boland Maurice , Lonergan Patrick 
Published: August 2002

AbstractThe objectives of this study were: (1) to evaluate the effect of sire on the time from insemination to first cleavage following insemination in vitro and the relationship of this parameter to field fertility and (2) to establish the relationship between the kinetics of cleavage in vitro and oocyte developmental competence for bulls of known field fertility. Frozen semen from six bulls with 150‐day non‐return rates ranging from 57–78% was used. In experiment 1, after insemination with semen from one of the six bulls, presumptive zygotes were transferred to IVC in droplets of synthetic oviduct fluid. Droplets were examined at 24, 27, 30, 33, 36, 42, and 48 hr after insemination and the number of cleaved oocytes was recorded. Blastocyst yield was recorded on Days 6‐, 7‐, and 8‐post insemination. In experiment 2, culture droplets were examined at 30, 36, and 48 hr after insemination. At each time point, the number of cleaved embryos was recorded and these embryos were transferred into new droplets and were cultured separately for the duration of the experiment. The proportion of embryos developing to the blastocyst stage was recorded for each of the groups for each bull. The best predictor of field fertility was a model containing 33‐hpi‐cleavage percentage only (r = 0.689, P < 0.0001). There was also a significant correlation between blastocyst yield and non‐return rate, with Day 7 blastocyst yield having the highest correlation (r = 0.356), although this was relatively low in comparison. In experiment 2, irrespective of sire, a significantly higher proportion of those early‐cleaving oocytes (before 30 hpi) developed to blastocysts than those cleaving later. In most cases, a higher proportion of blastocysts derived from early‐cleaving oocytes hatched from the zona pellucida suggesting that such blastocysts are of superior quality to those derived from late‐cleaving oocytes. In conclusion these data confirm our earlier observations that earliest cleaving zygotes are more competent in terms of development to the blastocyst stage than those that cleave later. This phenomenon is independent of the sire used. However, we have demonstrated that the kinetics of early embryonic development as measured by the timing of the first cleavage division post insemination vary between different bulls and that these differences can be used to discriminate between bulls of high and low bull field fertility. Mol. Reprod. Dev. 60: 47–55, 2001. © 2001 Wiley‐Liss, Inc.
Capacitation dependent activation of tyrosine phosphorylation generates two sperm head plasma membrane proteins with high primary binding affinity for the zona pellucida
Authors: Flesch F.M. , Wijnand E. , van de Lest C.H.A. , Colenbrander B. , van Golde L.M.G. , Gadella B.M. 
Published: August 2002

AbstractThe recognition and binding of sperm cells to the zona pellucida (the extracellular matrix of the oocyte) are essential for fertilization and are believed to be species specific. Freshly ejaculated sperm cells do not bind to the zona pellucida. Physiologically this interaction is initiated after sperm activation in the female genital tract (capacitation) via a yet unknown mechanism, resulting in the binding of a receptor in the apical sperm plasma membrane to the zona pellucida. In order to mimic this biochemically, we isolated zona pellucida fragments from gilt ovaries to prepare an affinity column with the intact zona pellucida structure and loaded this column with solubilized apical plasma membranes of boar sperm cells before and after in vitro capacitation. With this technique we demonstrated that two plasma membrane proteins of capacitated boar sperm cells showed high affinity for zona pellucida fragments. Further analysis showed that these proteins were tyrosine phosphorylated. Plasma membrane proteins from freshly ejaculated sperm cells did not exhibit any zona pellucida binding proteins, likely because these proteins were not tyrosine phosphorylated. Mol. Reprod. Dev. 60: 107–115, 2001. © 2001 Wiley‐Liss, Inc.
Male sterile mutant casanova gives clues to mechanisms of sperm–egg interactions in Drosophila melanogaster
Authors: Perotti Maria‐Elisa , Cattaneo Fabio , Pasini Maria E. , Vernì Fiammetta , Hackstein Johannes H.P. 
Published: August 2002

AbstractThe plasma membrane of the spermatozoa of Drosophila melanogaster contains two integral proteins with glycosidase activity, β‐N‐acetylglucosaminidase and α‐D‐mannosidase. Biochemical analysis and ultrastructural cytochemistry of spermatozoa of the autosomal male sterile mutant casanova reveal that at least one of these enzymes, β‐N‐acetylglucosaminidase, is crucial for sperm–egg interactions. casanova sperm are motile, morphologically normal, are transferred to the female at mating, but are unable to fertilize the eggs. The mutation was localised by deficiency mapping to the chromosomal region 95E8‐F7. Fluorimetric assays showed that the mutant's sperm have the same level of α‐D‐mannosidase activity as wild‐type sperm, whereas β‐N‐acetylglucosaminidase activity reaches only 51% of the wild‐type level. The biochemical characteristics of α‐D‐mannosidase and of the residual β‐N‐acetylglucosaminidase are the same as in wild‐type males. Ultrastructural localization of the enzymes indicated that casanova spermatozoa lacks β‐N‐acetylglucosaminidase on the plasma membrane covering the acrosome, whereas the location of this glycosidase at the terminal part of the sperm tail is indistinguishable from the wild‐type situation. The results strongly suggest that in Drosophila the β‐N‐acetylglucosaminidase of the plasma membrane covering the acrosome functions as a receptor for the glycoconjugates on the egg surface. We named the putative egg receptor EROS. This is the first evidence for an egg/sperm recognition system in insects. The mechanism is similar to those known from higher animals. Mol. Reprod. Dev. 60: 248–259, 2001. © 2001 Wiley‐Liss, Inc.
Proteome analysis of rat spermatogonia: Reinvestigation of stathmin spatio‐temporal expression within the testis
Authors: Guillaume Elisabeth , Evrard Bertrand , Com Emmanuelle , Moertz Ejvind , Jégou Bernard , Pineau Charles 
Published: August 2002

AbstractStathmin is a protein known to be involved in various cell processes including cell proliferation and differentiation. It has already been described in the testis but its recent identification using a proteomic approach in mitotic spermatogenetic stem cells named spermatogonia (Guillaume et al., 2000) has lead us to reinvestigate its expression within the testis. Stathmin and its mRNAs were studied in isolated cells by Western and Northern blots and in situ using immunohistochemistry. We demonstrated that stathmin is indeed expressed in spermatogonia, and that it is also intensively expressed in the meiotic spermatocytes and in the first generations of spermatids. Furthermore, we showed aggregations of the protein in the cytoplasm of the later generations of spermatids preceding its elimination at the time of spermiation. Our Northern blots reveal the presence of two stathmin transcripts of 1.1 and 3.2 kb within the testis from the fetal stage onwards, in spermatogonia, spermatocytes, and spermatids. However, the 3.2 kb RNA transcript was barely detectable in the spermatids. Stathmin expression is known to be associated with microtubule dynamics. Therefore, its expression in the germ line is most probably related to the extremely complex structural cellular rearrangements occurring in germ cells during spermatogenesis. However, the exact role of stathmin and the reason of the existence of two transcripts in the male germ lineage awaits further investigation. Mol. Reprod. Dev. 60: 439–445, 2001. © 2001 Wiley‐Liss, Inc.
Molecular cloning of Odf3 encoding a novel coiled‐coil protein of sperm tail outer dense fibers*†
Authors: Petersen Christoph , Aumüller Gerhard , Bahrami Masoud , Hoyer‐Fender Sigrid 
Published: August 2002

AbstractThe outer dense fibers (ODF) are the main cytoskeletal structures of the sperm tail found in animals with internal fecundation. They consist of at least 14 polypeptides from which only a few are identified due to difficulties in isolation of the protein components. Here we report the isolation and molecular characterization of Odf3, encoding a novel protein of rat sperm ODF. Odf3 is transcribed in testes and more specifically in spermatids but it is also expressed in epididymides and brain suggesting a possible involvement in building of the cellular cytoskeleton. Odf3 encodes a putative protein of ∼110 kDa. Secondary structure predictions indicated that ODF3 is a coiled‐coil protein. The identification of coiled‐coil proteins as constituents of outer dense fibers reveals a model for ODF formation. Mol. Reprod. Dev. 61: 102–112, 2002. © 2002 Wiley‐Liss, Inc.
Apoptosis and brain development
Authors: Roth Kevin A. , D'Sa Cleta 
Published: August 2002

AbstractNeuronal cell death in the embryonic brain was first recognized almost a century ago. Its significance for normal nervous system development and function has been a major focus of neuroscientific investigation ever since. Remarkable progress has been made in defining the cellular processes controlling neuronal cell death and studies performed over the last ten years have revealed extensive homology between the molecules regulating programmed cell death in Caenorhabditis elegans and apoptosis in mammalian cells. Targeted gene disruptions of members of the bcl‐2 and caspase gene families have demonstrated particularly significant roles for bcl‐x, bax, caspase‐9 and caspase‐3 in mammalian brain development. As expected from previous studies of synapse‐bearing neurons and neurotrophic factors, reduced neuronal cell death in mice bearing mutations in key pro‐apoptotic molecules resulted in increased numbers of neurons in a variety of neuronal subpopulations. However, targeted gene disruptions also demonstrated a heretofore underappreciated significance of neural precursor cell death and immature neuron death in nervous system development. Pathological activation of apoptotic death pathways may lead to neuroanatomic abnormalities and possibly to developmental disabilities. MRDD Research Reviews 2001;7:261–266. © 2001 Wiley‐Liss, Inc.
T2‐shortening by strongly magnetized spheres: A chemical exchange model†
Authors: Brooks Rodney A. 
Published: August 2002

AbstractIt is shown that a chemical exchange model can reproduce nuclear magnetic relaxation caused by diffusion of water molecules near strongly magnetized particles. The agreement is based on the similarity (but not equivalence) of the respective “visit‐limiting” mechanisms in the echo‐limited regime. The model leads to a single equation that predicts relaxation behavior in both the motional‐averaging and visit‐limited regimes. When combined with the static‐dephasing regime equation, the result is a simple theory (for spheres) that covers the entire range of diffusion times. Magn Reson Med 47:388–391, 2002. Published 2002 Wiley‐Liss, Inc.
T1 quantification with inversion recovery TrueFISP
Authors: Scheffler Klaus , Hennig Jürgen 
Published: August 2002

AbstractA snapshot FLASH sequence can be used to acquire the time course of longitudinal magnetization during its recovery after a single inversion pulse. However, excitation pulses disturb the exponential recovery of longitudinal magnetization and may produce systematic errors in T1 estimations. In this context the possibility of using the TrueFISP sequence to detect the recovery of longitudinal magnetization for quantitative T1 measurements was examined. Experiments were performed on different Gd‐doped water phantoms and on humans. T1 values derived from inversion recovery TrueFISP were in excellent agreement with the single‐point method even for flip angles up to 50°. In terms of T1 accuracy and SNR, the proposed method seems to be superior to the conventional inversion recovery snapshot FLASH technique. Magn Reson Med 45:720–723, 2001. © 2001 Wiley‐Liss, Inc.
Trabecular bone volume fraction mapping by low‐resolution MRI
Authors: Fernández‐Seara M.A. , Song H.K. , Wehrli F.W. 
Published: August 2002

AbstractTrabecular bone volume fraction (TBVF) is highly associated with the mechanical competence of trabecular bone. TBVF is ordinarily measured by histomorphometry from bone biopsies or, noninvasively, by means of high‐resolution microcomputed tomography and, more recently, by micro‐MRI. The latter methods require spatial resolution sufficient to resolve trabeculae, along with segmentation techniques that allow unambiguous assignment of the signal to bone or bone marrow. In this article it is shown that TBVF can be measured under low‐resolution conditions by exploiting the attenuation of the MR signal resulting from fractional occupancy of the imaging voxel by bone and bone marrow, provided that a reference signal is available from a marrow volume devoid of trabeculation. The method requires accurate measurement of apparent proton density, which entails correction for various sources of error. Key among these are the spatial nonuniformity in the RF field amplitude and effects of the slice profile, which are determined by B1 field mapping and numerical integration of the Bloch equations, respectively. By contrast, errors from variations in bone marrow composition (hematopoietic vs. fatty) between trabecular and reference site are predicted to be small and usually negligible. The method was evaluated in phantoms and in vivo in the distal radius and found to be accurate to 1% in marrow volume fraction. Finally, in a group of 12 patients of varying skeletal status, TBVF in the calcaneus was found to strongly correlate with integral bone mineral density of the lumbar vertebrae (r2 = 0.83, p < 0.0001). The method may fail in large imaging objects such as the human trunk at high magnetic field where standing wave and RF penetration effects cause intensity variations that cannot be corrected. Magn Reson Med 46:103–113, 2001. © 2001 Wiley‐Liss, Inc.
Effect of black blood MR image quality on vessel wall segmentation
Authors: Thomas Jonathan B. , Rutt Brian K. , Ladak Hanif M. , Steinman David A. 
Published: August 2002

AbstractBlack blood MRI has become a popular technique for measuring arterial wall area as an indicator of plaque size. Computer‐assisted techniques for segmenting vessel boundaries have been developed to increase measurement precision. In this study, the carotid arteries of four normal subjects were imaged at seven different fields of view (FOVs), keeping all other imaging parameters fixed, to determine whether spatial resolution could be increased at the expense of image quality without sacrificing precision. Wall areas were measured via computer‐assisted segmentation of the vessel boundaries performed repeatedly by two operators. Analysis of variance (ANOVA) demonstrated that the variability of wall area measurements was below 1.5 mm2 for in‐plane spatial resolutions between 0.22 mm and 0.37 mm. An inverse relationship between operator variability and the signal difference‐to‐noise ratio (SDNR) demonstrated that semi‐automatic segmentation of the wall boundaries was robust for SDNR >3, defining a criterion above which subjective image quality can be degraded without an appreciable loss of information content. Our study also suggested that spatial resolutions higher than 0.3 mm may be required to quantify normal wall areas to within 10% accuracy, but that the reduced SNR associated with the higher resolution may be tolerated by semi‐automated wall segmentation without an appreciable loss of precision. Magn Reson Med 46:299–304, 2001. © 2001 Wiley‐Liss, Inc.
Contractile properties of adjacent segments of single human muscle fibers
Authors: Wilkins John T. , Krivickas Lisa S. , Goldstein Richard , Suh Dongwon , Frontera Walter R. 
Published: August 2002

AbstractA comparison of the contractile properties of adjacent segments of single human muscle fibers may help to explain the interaction among nuclear domains within the myofiber. Biopsy samples were obtained from the vastus lateralis muscle of 20 healthy untrained women (age 18–79 years). Single fibers (n = 38) were dissected and cut into halves (segments A and B). Segment diameter and depth were measured using an image analysis system. Maximal force (Po) was recorded during activation with calcium (pCa 4.5). Maximal unloaded shortening velocity (Vo) was calculated using the slack test. Myosin heavy chain (MyHC) expression was determined using sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS‐PAGE). A significant difference (∼7%) in Po was seen between adjacent segments expressing type I MyHC that could not be attributed to differences in fiber size. Significant differences were observed in Vo even after adjusting for fiber type. A positive correlation was seen in Po (concordance coefficient Rho_C = 0.803) and Vo (Rho_C = 0.690) between segments, but concordance was less than perfect in both cases. Possible explanations for nonuniformity of contractile properties include random variations in physiological systems or variability of protein expression among nuclear domains. © 2001 John Wiley & Sons, Inc. Muscle Nerve 24: 1319–1326, 2001
Obtaining force–frequency curves with a single 3‐second train of stimuli
Authors: Meyers B.M. , Nguyen J. , Cafarelli E. 
Published: August 2002

AbstractWe devised a method to assess the force–frequency relationship (FFR) in human skeletal muscle that involved delivery of a single 2.8‐s train of shocks directly to the femoral nerve. This increasing‐frequency train (IFT) was based on a power function, with a range of stimulation frequencies beginning at 5 Hz and rising to 100 Hz. We compared the IFT to a standard series of constant‐frequency trains (CFT) under two conditions. Force–frequency curves were examined, first in response to altered muscle length and second, following fatigue. There was no leftward shift in the curve when the knee extensors were shortened, although maximal force increased. In contrast, we observed a rightward shift in the curve after fatigue with both protocols; the frequency required to develop 50% of maximal force increased by 48% (P < .01) with CFT and 58% (P < .001) with an IFT. The CFT produced an irregular pattern of low‐frequency fatigue recovery. In the IFT, low‐frequency fatigue was greatest at the onset of recovery and decreased linearly until 120 s. These experiments show that the IFT protocol reveals alterations in muscle performance similar to the more traditional CFT. However, it requires only 2.8 s to administer and was judged more tolerable by 70% of our subjects. This suggests that the IFT may be an effective alternative for determining the FFR in human muscle for clinical and experimental purposes. © 2001 John Wiley & Sons, Inc. Muscle Nerve 24: 1332–1338, 2001
Peripheral neuropathy in young‐old and old‐old patients
Authors: Verghese J. , Bieri P.L. , Gellido C. , Schaumburg H.H. , Herskovitz S. 
Published: August 2002

AbstractDiabetes is said to account for most cases of neuropathy in the elderly. We reviewed records of 223 young‐old (65–79 years) and 77 old‐old (≥80 years) patients referred for evaluation of neuropathic symptoms over a 9‐year period. We prospectively validated our findings in 102 consecutive elderly (77 young‐old) patients receiving intensive evaluation for neuropathy. Diabetes was the most common cause of neuropathy (41%), but was less common in the old‐old (25% versus 46%, P < 0.001). Idiopathic neuropathies were more common in the old‐old (39% versus 9%, P < 0.001). Alcoholic and nutritional neuropathies were uncommon in the old‐old. Electrophysiological studies showed that most patients had an axonal type of neuropathy. Sural and peroneal response amplitudes were poorly correlated with age. We obtained similar results in our prospective study. The distribution of causes of neuropathies in young‐old and old‐old patients, in a hospital‐based sample, is age‐related. Future studies need to include the old‐old to better understand the nature of neuropathy in the elderly. © 2001 John Wiley & Sons, Inc. Muscle Nerve 24: 1476–1481, 2001