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Apoptosis is the underlying mechanism of follicular atresia in the mammalian ovary. However, the apoptotic pathways governing this ovarian process are not completely elucidated. In the present study, expression of Fas and Fas ligand, the proximal members of the death receptor pathway, was evaluated in mouse ovarian follicles using immunofluorescence and in situ hybridization. Normal or atretic follicles were obtained from immature female Swiss mice after administration of 10 iu equine chorionic gonadotrophin for 48 or 72 h, respectively. Expression of both Fas and Fas ligand mRNA and protein was observed in granulosa cells of normal and atretic follicles. Although the oocytes of normal follicles failed to show any staining, those of atretic follicles stained intensely for Fas, indicating that the presence of Fas in the oocyte determines the fate of the follicle. 相似文献
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High voltage electron microscope (hvem) has been extensively used to produce radiation damage and to study the characteristics of defects so produced in crystalline
solids. To understand the defect production in metallic glasses and to evaluate the influence of such defects on physical
properties like crystallisation temperature etc., high voltage microscopy and subsequentin situ heating and observation has been extremely useful technique. This paper gives a qualitative overview of such work performed
in metallic glasses. In particular results obtained on a nickel based metallic glass using ahvem and an electron accelerator are presented. The advantages and limitations ofhvem irradiation are highlighted. 相似文献
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The optical responses of two sides of float glass in the soft-x-ray region were studied at the Indus-1 synchrotron facility. To the best of our knowledge these are the first experimentally obtained optical data for both sides of float glass in the soft-x-ray region. Optical constants delta and beta were determined by use of angle-dependent reflectance techniques in the wavelength range 80-200 A. On the side of the glass that was tin indiffused, a significant difference in delta value from that of the non-tin-side surface was observed. The measured data were compared with Henke's tabulated value of SiO2. The surface roughness of float glass was separately determined by hard-x-ray reflectivity to minimize the number of fitting variables. The effect of a contamination layer on the determination of optical constants was avoided by an appropriate sample-cleaning method. 相似文献
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Motor unit action potentials (MUAPs) were recorded with a standard concentric needle electrode inserted into the right biceps brachii muscle with different angular orientations of the beveled recording surface to the muscle fibers. Contrary to the predictions from computer simulations, the MUAP duration remained constant during needle rotation. This finding is used to reexamine the previous assumptions regarding the concentric needle's spatial uptake recording territory and the implications with respect to MUAP duration measurements. 相似文献
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The factors contributing to the duration of a motor unit action potential (MUAP) are believed to be well known, with both manual measurements and computer simulations agreeing with respect to MUAP durations approaching 10 ms. In this investigation, it is clearly demonstrated that use of a wide-open amplifier bandpass combined with signal-to-noise ratio enhancement results in MUAP durations approaching 30 ms recorded with either a macro or single-fiber electrode. Why the clinically recorded MUAP duration differs significantly from these physiologic durations is discussed. A hypothesis is presented whereby the major contributing factor toward MUAP duration is the total time of action potential transmembrane current flow along the muscle fiber from end-plate zone to musculotendinous junction. 相似文献
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MA Nandedkar J Palazzo SL Abbondanzo J Lasota M Miettinen 《Canadian Metallurgical Quarterly》1998,11(12):1204-1210
Leukocyte common antigen (CD45/LCA) and keratin expression are generally mutually exclusive in diagnostic surgical pathology. CD45 reactivity is a reliable indicator of the hematolymphoid nature of a tumor, whereas keratin reactivity is typical of epithelial differentiation (carcinomas and some sarcomas). Some lymphomas, however, might lack detectable CD45 expression, whereas occasional ones might express keratins. CD45 immunoreactivity has been considered exquisitely specific for hematopoietic cells. We report three undifferentiated or neuroendocrine carcinomas that showed membrane-associated immunoreactivity for CD45 in addition to showing distinctive keratin cocktail (AE1/AE3) and epithelial membrane antigen reactivity (all cases); also, keratin 7 was demonstrated in one case and keratin 19 in another. Two cases were lymph node metastases of undifferentiated carcinomas, one of them from the lungs and the other of an unknown origin; the former case showed neuroendocrine features. The third case represented a pulmonary large-cell undifferentiated carcinoma. These cases were negative for lineage-specific leukocyte antigens and did not show clonal immunoglobulin heavy-chain gene rearrangements. Electron microscopic studies demonstrated desmosomes and keratin-like tonofilaments in all three cases, thus confirming the epithelial nature of these tumors. The exceptional membrane staining for CD45 seen in these undifferentiated carcinomas might be comparable to experimentally detected incorporation of leukocyte antigens into the cell membranes of nonleukocytic cells in a leukocyte-rich environment. This rare diagnostic pitfall should be considered in the diagnostic surgical pathology of undifferentiated tumors. It is best avoided by employing a panel of leukocyte and epithelial antigens and by use of electron microscopy, if possible. 相似文献
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Ankur Nandedkar 《Computers in human behavior》2012,28(1):41-48
Piracy continues to be a threat to the global economy. Previous literature on factors influencing individual’s attitude towards piracy indicates that as perceived risk increases, individuals attitude of acceptance of piracy should decrease. In spite of the increased risks, some people pirate, there has been no explanation for this apparent paradox. We attempt to explain this paradox by using the concept of optimism bias. Results of structural equation modeling using a sample of 219 college students provide evidence that individuals having an optimism bias engage in piracy because they consider themselves to be at lower risk than average compared to a group. Implications for practice and future research avenues are discussed. 相似文献
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Nandedkar SD Nandedkar DS Barkhaus PE Stalberg EV 《IEEE transactions on bio-medical engineering》2004,51(12):2209-2211
The surface-recorded compound muscle action potential (CMAP) and electromyographic (EMG) interference pattern is used to compute the motor unit number index (MUNIX). The MUNIX demonstrated all known changes in the number of motor units in normal subjects, and in patients with amyotrophic lateral sclerosis (ALS). In normal subjects MUNIX decreased slightly with age and showed excellent reproducibility. In many ALS patients MUNIX was reduced even when the CMAP was normal. Lower MUNIX values were seen in weaker muscles. This is a noninvasive method that requires minimal electrical stimulation. It is performed in less than 5 min. This makes it suitable for serial EMG investigations. 相似文献