bluuebunny/crossref_metadata_2025_split huggingface dataset:
Specific localization of transcription factors in the chromatin of mouse mature spermatozoa
Authors: Pittoggi Carmine , Magnano Anna Rosa , Sciamanna Ilaria , Giordano Roberto , Lorenzini Rodolfo , Spadafora Corrado 
Published: August 2002

AbstractWe previously characterized a nuclease‐hypersensitive fraction of mouse sperm chromatin, which is organized in a typical nucleosomal structure. A partial genomic library was constructed with the DNA from the nuclease‐hypersensitive chromatin, which revealed a high content in retroposon/retroviral DNA sequences. Here we report that the cloned nuclease‐hypersensitive DNA also contains clusters of potential sites for transcription factors: among those, binding sites for Oct‐1, Oct‐4, TBP, Ets‐1, and C/EBP are most abundant. This observation prompted us to ask whether mature spermatozoa contain the corresponding protein factors. Indirect immunofluorescence experiments show that all analyzed factors are indeed present in the sperm heads. Moreover, transcription factors are associated with the nuclease‐hypersensitive chromatin of spermatozoa, as endogenous nucleases that degrade the hypersensitive fraction also cause the concomitant release of transcription factors from sperm cells into the medium. Band‐shift assays with proteins extracted from the supernatant, and immunofluorescence analysis of sperm pellets, indicate that transcription factors are largely recovered in the supernatant while being absent or poorly retained in spermatozoa. The possible involvement of these factors in early embryogenesis is discussed. Mol. Reprod. Dev. 60: 97–106, 2001. © 2001 Wiley‐Liss, Inc.
Nuclear transfer in cattle with non‐transfected and transfected fetal or cloned transgenic fetal and postnatal fibroblasts
Authors: Zakhartchenko Valeri , Mueller Sigrid , Alberio Ramiro , Schernthaner Wolfgang , Stojkovic Miodrag , Wenigerkind Hendrik , Wanke Rüdiger , Lassnig Caro , Mueller Mathias , Wolf Eckhard , Brem Gottfried 
Published: August 2002

AbstractThe efficiency of nuclear transfer (NT) using two primary cultures of fetal fibroblasts (FF1 and FF2) was compared vs. the same cultures transfected with an expression vector in which the bovine prochymosin coding sequence is placed under the control of the bovine αS1‐casein promoter (TFF1 and TFF2). In addition, fibroblasts of a cloned transgenic fetus (TRFF1) derived from TFF1 and ear skin fibroblasts of a 1‐month‐old cloned transgenic calf (TRCF1) derived from TRFF1 were used as nuclear donors. Embryos reconstructed from FF1 (44%) and FF2 (52%) developed to the blastocyst stage at a significantly (P < 0.05) higher rate than those derived from TFF1 (24%) and TFF2 (27%). The proportions of cleaved embryos and blastocysts were significantly (P < 0.05) higher with TRFF1 than with TRCF1 used as nuclear donors (75 vs. 66% and 33 vs. 16%, respectively). Transfer of NT embryos derived from FF2 and TFF2 to recipients resulted in similar pregnancy rates on day 30 (52 and 48%, respectively). However, with TFF2 embryos, the majority of pregnancies (8/11; 73%) was lost in the first and second trimesters of gestation, whereas 4/11 (36%) pregnancies with FF2 embryos were lost during the full period of in vivo development. Of 11 FF2 and 6 TFF2 born calves (25 and 13% of transferred embryos, respectively), 6 and 3 survived including one oversized FF2 calf. After transfer of TRFF1 and TRCF1 NT embryos to recipients, initial pregnancy rate was as a tendency higher in the TRFF1 (49%) than in the TRCF1 group (30%). The majority (14/17) of TRFF1 pregnancies and all TRCF1 pregnancies were lost in the first and second trimester. A high proportion of TRFF1 calves (5/8) showed increased body weights, and only two calves which were also large survived. These findings demonstrate that (i) extended culture associated with transfection and selection procedures may induce changes of donor cells which markedly decrease the efficiency of nuclear transfer and (ii) these changes are not reversed by recloning. Mol. Reprod. Dev. 60:362‐369, © 2001 Wiley‐Liss, Inc.
Effect of sperm cryopreservation on sperm DNA stability and progeny development in rainbow trout
Authors: Labbe Catherine , Martoriati Alain , Devaux Alain , Maisse Gerard 
Published: August 2002

AbstractThis study was carried out to test how sperm cryopreservation affected nuclear DNA stability and whether progeny development was modified when eggs were fertilized with cryopreserved spermatozoa. The “comet assay” (alkaline single‐cell gel electrophoresis assay) was adapted to trout spermatozoa to estimate DNA stability as measured by alkali‐induced DNA strand break formation. Because trout eggs develop in water after fertilization (oviparous species) and that eggshell is easy to clear up after fixative treatment, progeny development was assessed from the blastodisc flattening stage of the embryos to the first feeding stage of the hatched fries by direct observation. All parameters under study were analyzed on each sperm and comparisons between parameters were made using paired data. Freeze–thawing of sperm slightly but significantly increased the percentage of nuclei showing altered DNA after comet assay. This increase was correlated to the decrease in fertilization rates of sperm, but the absolute percentage of altered nuclei was not predictive of the absolute fertilization ability of sperm. Assessment of progeny development showed that survival rate and abnormality rate obtained after fertilization with cryopreserved sperm were not different from those obtained with fresh sperm. It is concluded that trout sperm cryopreservation only slightly affected sperm DNA stability and that the use of cryopreserved spermatozoa did not impair offspring survival and quality. Mol. Reprod. Dev. 60:397‐404, © 2001 Wiley‐Liss, Inc.
Cryopreservation alters membrane sulfhydryl status of bull spermatozoa: Protection by oxidized glutathione
Authors: Chatterjee Suvro , de Lamirande Eve , Gagnon Claude 
Published: August 2002

AbstractCryopreservation induces extensive biophysical and biochemical changes in the membrane of spermatozoa that ultimately decrease the fertility potential of the cells. Sulfhydryl groups of sperm proteins regulate a number of activities of the cells. Qualitative and quantitative analyses of sulfhydryl groups in the sperm membrane were performed by fluorescence microscopy, fluorimetry and electrophoresis. Fluorimetric analysis using 5‐iodoacetamidofluoresceine indicated a two‐fold increase in the content of sulfhydryl groups in sperm membrane after a freezing/thawing cycle. Electrophoresis of Triton‐soluble sperm proteins after labeling with 3‐(N‐maleimidylpropionyl) biocytin indicated that proteins of 40–65 and 34 kDa range expose more sulfhydryl groups after cooling at 4°C and freezing/thawing. Cryopreservation of spermatozoa changed the distribution pattern of sulfhydryl groups on sperm surface measured with fluorescence microscopy using 5‐iodoacetamidofluoresceine. The percentage of spermatozoa labeled at the level of the mid‐piece decreased by 50 and 90% after cooling and freezing/thawing, respectively. Spin labeling studies showed a 15% faster rotational diffusion (mobility) of sulfhydryl containing proteins in the membrane of frozen/thawed spermatozoa as compared to that of fresh spermatozoa. Addition of glutathione, reduced (GSH) or oxidized (GSSG), to the cryoprotectant partially prevented the effects of freezing/thawing, such as higher exposure of sulfhydryl groups, changes in the cellular distribution, and enhanced rotational diffusion of sulfhydryl containing proteins of sperm membrane. Addition of GSSG to the cryoprotectant reduced by 35% the loss of motility of spermatozoa undergoing a freezing/thawing cycle. We concluded that cryopreservation perturbs sperm membrane sulfhydryl containing proteins and that these modifications could be partially prevented by the addition of GSSG to the cryopreservation medium. Mol. Reprod. Dev. 60: 498–506, 2001. © 2001 Wiley‐Liss, Inc.
Direct injection of foreign DNA into mouse testis as a possible in vivo gene transfer system via epididymal spermatozoa
Authors: Sato Masahiro , Ishikawa Aki , Kimura Minoru 
Published: August 2002

AbstractWe have attempted to transfect testicular spermatozoa with plasmid DNA by direct injection into testes to obtain transgenic animals [this technique was thus termed “testis‐mediated gene transfer (TMGT)”]. When injected males were mated with superovulated females 2 and 3 days after injection, (i) high efficiencies (more than 50%) of gene transmission were achieved in the mid‐gestational F0 fetuses, (ii) the copy number of plasmid DNA in the fetuses was estimated to be less than 1 copy per diploid cell, and (iii) overt gene expression was not found in these fetuses. These findings suggest the possibility that plasmid DNA introduced into a testis is rapidly transported to the epididymis and then incorporated by epididymal spermatozoa. The purpose of this study was to elucidate the mechanism of TMGT by introducing trypan blue (TB) or Hoechst 33342 directly into testis. We found that TB is transported to the ducts of the caput epididymis via rete testis within 1 min after testis injection, and TB reached the corpus and cauda epididymis within 2–4 days after injection. Staining of spermatozoa isolated from any portion of epididymis was observed 4 days after injection of a solution containing Hoechst 33342. Injection of enhanced green fluorescent protein (EGFP) expression vector/liposome complex into testis resulted in transfection of epithelial cells of epididymal ducts facing the lumen, although the transfection efficiency appeared to be low. In vivo electroporation toward the caput epididymis immediately after injection of EGFP expression vector into a testis greatly improved the uptake of foreign DNA by the epididymal epithelial cells. PCR analysis using spermatozoa isolated from corpus and cauda epididymis 4 days after injection of a DNA/liposome complex into testis revealed exogenous DNA in these spermatozoa even after treatment with DNase I. These findings indicate that exogenous DNA introduced into tesits is rapidly transported to epididymal ducts via the rete testis and efferent ducts, and then incorporated by epithelial cells of epididymis and epididymal spermatozoa. Mol. Reprod. Dev. 61: 49–56, 2002. © 2002 Wiley‐Liss, Inc.
Identification of the major tyrosine phosphorylated protein of capacitated hamster spermatozoa as a homologue of mammalian sperm a kinase anchoring protein
Authors: Jha Kula Nand , Shivaji S. 
Published: August 2002

AbstractThe molecular basis of mammalian sperm capacitation is unique in that, it is associated with a protein kinase A (PKA) dependent upregulation of protein tyrosine phosphorylation. Therefore, PKA activity during capacitation would be crucial for the downstream events of protein tyrosine phosphorylation, and mechanisms may exist to ensure that PKA phosphorylates its specific substrate. This could be achieved by bringing PKA close to its substrate, a function normally carried out by an A‐kinase anchoring protein (AKAP). We showed previously that cauda epididymidal spermatozoa of hamster undergo a capacitation‐dependent increase in protein tyrosine phosphorylation. In the present study, evidence is provided that two major tyrosine phosphorylated proteins of molecular weight 97 and 83 kDa are the hamster homologues of mouse pro‐AKAP82 and AKAP82, and have been designated as hamster pro‐AKAP83 and AKAP83 respectively. Hamster AKAP83 resembled the mouse AKAP82 with respect to its molecular weight, pI (pH 5–5.5) and cDNA and amino acid sequences. Sequence analysis indicated that the primary structure of pro‐AKAP83 was highly conserved and exhibited 91% identity with mouse and rat AKAP82. Further, the functional domains, namely the region involved in binding the regulatory subunit of PKA and the proteolytic cleavage site between pro‐AKAP83 and AKAP83, were identical with that observed in rat and mouse pro‐AKAP82 and AKAP82. Immunoblot analysis using polyclonal hamster anti‐AKAP83 antibodies indicated that AKAP83 was present both in caput and cauda epididymidal spermatozoa. The antibody also identified the pro‐AKAP82 and AKAP82 in mouse caput and cauda epididymidal spermatozoa. Immunofluorescence studies indicated that AKAP83 in hamster spermatozoa was localized along the length of principal piece of the tail. It was also demonstrated that hamster pro‐AKAP83/AKAP83 gene expression was testis specific and was not expressed in other organs in either sex. This is the first report implicating AKAP in capacitation in rodents. Mol. Reprod. Dev. 61: 258–270, 2002. © 2002 Wiley‐Liss, Inc.
Planar strip array (PSA) for MRI
Authors: Lee Ray F. , Westgate Charles R. , Weiss Robert G. , Newman David C. , Bottomley Paul A. 
Published: August 2002

AbstractParallel, spatial‐encoded MRI requires a large number of independent detectors that simultaneously acquire signals. The loop structure and mutual coupling in conventional phased arrays limit the number of coils and therefore the potential reduction in minimum scan time achievable by parallel MRI tchniques. A new near‐field MRI detector array, the planar strip array (PSA), is presented that eliminates the coupling problems and can be extended to a very large number of detectors and high MRI frequencies. Its basic structure is an array of parallel microstrips with a high permittivity substrate and overlay. The electromagnetic (EM) wavelength can be adjusted with the permittivity, and the strip lengths tuned to a preselected fraction of the wavelength of the MRI frequency. EM wave analysis and measurements on a prototype four‐element PSA reveal that the coupling between the strips vanishes when the strip length is either an integer times a quarter wavelength for a standing‐wave PSA, or a half wavelength for a travelling‐wave PSA, independent of the spacing between the strips. The analysis, as well as phantom and human MRI experiments performed by conventional and parallel‐encoded MRI with the PSA at 1.5 T, show that the decoupled strips produce a relatively high‐quality factor and signal‐to‐noise ratio, provided that the strips are properly terminated, tuned, and matched or coupled to the preamplifiers. Magn Reson Med 45:673–683, 2001. © 2001 Wiley‐Liss, Inc.
Perfusion imaging using dynamic arterial spin labeling (DASL)†
Authors: Barbier Emmanuel L. , Silva Afonso C. , Kim Seong‐Gi , Koretsky Alan P. 
Published: August 2002

AbstractRecently, a technique based on arterial spin labeling, called dynamic arterial spin labeling (DASL (Magn Reson Med 1999;41:299–308)), has been introduced to measure simultaneously the transit time of the labeled blood from the labeling plane to the exchange site, the longitudinal relaxation time of the tissue, and the perfusion of the tissue. This technique relies on the measurement of the tissue magnetization response to a time varying labeling function. The analysis of the characteristics of the tissue magnetization response (transit time, filling time constant, and perfusion) allows for quantification of the tissue perfusion and for transit time map computations. In the present work, the DASL scheme is used in conjuction with echo planar imaging at 4.7 T to produce brain maps of perfusion and transit time in the anesthetized rat, under graded hypercapnia. The data obtained show the variation of perfusion and transit time as a function of arterial pCO2. Based on the data, CO2 reactivity maps are computed. Magn Reson Med 45:1021–1029, 2001. Published 2001 Wiley‐Liss, Inc.
Analysis of volume MRI and MR spectroscopic imaging data for the evaluation of patients with brain tumors
Authors: Nelson Sarah J. 
Published: August 2002

AbstractThe combination of volumetric MRI and multivoxel localized MR spectroscopic imaging (MRSI) data provides the potential for quantifying variations in tissue morphology and function. These techniques have numerous applications for the evaluation of neurological diseases. While state‐of‐the‐art whole‐body MR scanners are able to acquire both types of data, there have been relatively few reports which have presented clinical applications of the technology. One of the reasons for this has been the need to develop software for reconstruction and reliable interpretation of 3D imaging and spectral data. In this article, we describe the strategy developed for quantitative analysis of combined MRI and MRSI examinations from patients with brain tumors and evaluate the key components of this procedure using both simulations and empirical data from phantoms, normal volunteers, and patients. Important factors are the use of volume or interleaved multislice anatomic images as a reference, the reconstruction and correction of the spectral data for frequency, phase, and baseline distortions and consideration of the characteristics of the coil, RF pulses used for spatial selection, and phase encoding procedures. These studies show that the metabolic parameters most critical for distinguishing tumor from normal and necrotic tissue were relative levels of choline and NAA. Levels of creatine and lactate were found to be variable, both in terms of their spatial distribution within individual lesions and between different patients. Magn Reson Med 46:228–239, 2001. © 2001 Wiley‐Liss, Inc.
On the theoretical basis of perfusion measurements by dynamic susceptibility contrast MRI
Authors: Kiselev V.G. 
Published: August 2002

AbstractA quantitative analysis was undertaken to calibrate the perfusion quantification technique based on tracking the first pass of a bolus of a blood pool contrast agent. A complete simulation of the bolus passage, of the associated changes in the T2 and T signals, and of the data processing was performed using the tracer dilution theory, an analytical theory of the MR signal from living tissues and numerical simulations. The noise was excluded in the simulation in order to analyze the ultimate accuracy of the method. It is demonstrated that the relationship between the contrast agent concentration and the associated changes in the transverse relaxation rate shows essentially different forms in studied tissue and in the reference artery. This effect results in systematic deviations of the measured blood flow, blood volume, and the residue function obtained with conventional processing from their true values. The error depends on the microvascular composition, the properties of the contrast agent, and the weights of the various compartments in the total signal. The results show that dynamic susceptibility contrast MRI can reach the goal of absolute perfusion quantification only with additional input from measurements of the microvascular architecture. Alternatively, the method can be used to provide such information if the perfusion is quantified by another modality. Magn Reson Med 46:1113–1122, 2001. © 2001 Wiley‐Liss, Inc.
Myotonic dystrophy type 1 (DM1) presenting with laryngeal stridor and vocal fold paresis
Authors: Ahmadian Jennifer L. , Heller Scott L. , Nishida Takashi , Altman Kenneth W. 
Published: August 2002

AbstractMyotonic dystrophy type 1 (DM1) is the most common inherited muscle disorder and may present in numerous ways due to characteristic multisystem involvement. We report a 47‐year‐old man who presented with an 8‐year history of slowly progressive dyspnea and episodic stridor. The laryngeal paresis was documented with videostroboscopy and laryngeal electromyography, and treated with tracheostomy and antimyotonia agents. © 2002 Wiley Periodicals, Inc. Muscle Nerve 25: 000–000, 2002
The spread of transgene expression at the site of gene construct injection
Authors: O'Hara Amanda J. , Howell John McC , Taplin Ross H. , Fletcher Sue , Lloyd Frances , Kakulas Byron , Lochmüller Hanns , Karpati George 
Published: August 2002

AbstractSeven 2‐day‐old golden retriever pups were given focal intramuscular injections of a first generation adenovirus–dystrophin minigene construct and adenovirus–β‐galactosidase construct as a 2:1 mixture into the left anterior tibial muscle. The spread of transgene expression within the anterior tibial muscle was compared with the spread of methylene blue dye after identical injection into the contralateral muscle. Transgene expression 5–7 days after intramuscular injection was shown to extend between 5.8 and 11.6 mm along the biopsied muscle length (range of biopsy lengths 11.1–12.2 mm). The level of transgene expression at 2–2.5‐mm intervals from the site of injection was significantly related to the distance from the site of injection (dystrophin, P = 0.009; β‐galactosidase, P = 0.015). The spread of methylene blue dye within the anterior tibial muscle ≤24 h after identical intramuscular injection demonstrated a similar pattern to the transgene expression, with dye staining measured between 5.5 and 8.5 mm along the muscle sample length (range of biopsy lengths 5.6–15.6 mm). The greatest transgene expression and dye staining was measured 2–2.5 mm proximal to the site of injection with a maximum of 23% of muscle fibers expressing the dystrophin transgene, 95.2% expressing the β‐galactosidase transgene, and 98% of the tissue section stained with methylene blue dye. These results suggest transgene expression after focal intramuscular injection is relatively localized around the site of injection. Further research is required to develop techniques that will provide transgene expression throughout the length and breadth of a muscle. © 2001 John Wiley & Sons, Inc. Muscle Nerve 24: 488–495, 2001.
Variation in motor threshold with frequency using kHz frequency alternating current
Authors: Ward Alex R. , Robertson Valma J. 
Published: August 2002

AbstractWe investigated the frequency dependence of motor thresholds over the frequency range 1 kHz to 25 kHz. Alternating current (AC), ramped in intensity, was applied transcutaneously, and the induced wrist extensor torque was measured. Plots of log torque versus stimulus voltage were used to accurately determine thresholds. Three kinds of sinusoidal AC stimuli were compared: continuous, 10 ms bursts at 50 Hz, and 50‐Hz single‐cycle. Differences were attributed to summation of subthreshold depolarizations. The variation in relative thresholds (continuous/single‐cycle and burst/single‐cycle) indicates that summation occurs more efficiently at higher kHz frequencies. The observed frequency and waveform dependence provides evidence for high‐frequency nerve fiber firing rates and fiber dropout when continuous or modulated AC is used, with the effects increasing with AC frequency. The form of the motor response evoked at high frequencies has features that suggest that frequencies above 10‐kHz have little or no useful clinical role in rehabilitation procedures. © 2001 John Wiley & Sons, Inc. Muscle Nerve 24: 1303–1311, 2001
Obstetric lesions of the brachial plexus
Authors: van Dijk J. Gert , Pondaag Willem , Malessy Martijn J. A. 
Published: August 2002

AbstractThe few studies on prognosis of obstetric lesions of the brachial plexus that are not hampered by selection bias or a short follow‐up suggest that functional impairment persists in 20–25% of cases, more than commonly thought. Electromyography (EMG), potentially useful for prognosis, is often considered of little value. Denervation in the first week of life has been interpreted as evidence of an antenatal lesion, but is the logical result of the short axonal length affected. EMG performed at close to the time of possible intervention (3 months) usually shows a discrepancy: motor unit potentials are seen in clinically paralyzed muscles. This can be explained in five ways: an overly pessimistic clinical examination; overestimation of EMG recruitment due to small muscle fibers; persistent fetal innervation; developmental apraxia; or misdirection, in which axons reach inappropriate muscles. Further research into the pathophysiology of obstetric lesions of the brachial plexus is needed to improve prognostication. © 2001 John Wiley & Sons, Inc. Muscle Nerve 24: 1451–1461, 2001