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R. Meyer J. Wiemer J. Dembski H. G. Haas 《Pflügers Archiv : European journal of physiology》1987,408(4):390-394
A method to monitor contraction of isolated myocytes by transmicroscopic photometry is illustrated. Two photodiodes are mounted inside an inverse microscope used for visual control of a cell. Illumination of one diode varies in proportion to changes in cell length. The contraction signal is amplified in a comparator circuit. Spatial resolution of the device is in the order of 1 m which corresponds to about 5% of cell shortening in the fully activated state of contraction. The method was tested on isolated myocytes from guinea-pig ventricle. Optical records of contraction in response to action potentials or during voltage clamp compare well with the contractile behaviour of multicellular preparations. 相似文献
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Co-culture techniques using fetal bovine uterine fibroblasts or bovine oviductal epithelial cells have improved embryonic development prior to replacement in humans. In initial co-culture trials, embryo development and implantation rates increased after just 1 day in culture. The most overt characteristics noted following co-culture were improved blastomere development and characteristics, reduced fragmentation, and the appearance of swollen blastomeres. In addition, an increase in the incidence of zona thickness variation was detected. Improved development of polyspermic and supernumerary embryos to the blastocyst stage was noted in initial trials. Retrospective analysis indicated that certain patient subgroups benefit the most from co-culture. As a result, co-culture is now applied routinely to patients that have previously failed attempts at in-vitro fertilization (IVF) and/or have endocrine imbalances such as polycystic ovarian syndrome and elevated day 3 concentrations of follicle stimulating hormone (FSH). The use of co-culture prior to or following cryopreservation has also proven to be beneficial to human embryos. The proposed beneficial mechanisms thought to improve embryonic development include a secretory and/or a scavenging role. Evidence describing the postulated benefits is discussed. 相似文献
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The variability in pregnancy rates achieved among in-vitro fertilization (IVF) clinics may be partially attributable to the disparate quality of the water used in the preparation of culture media. The removal of contaminants in the water is of paramount importance since water constitutes the predominant component in any media formulation. To assist in the selection, operation and maintenance of a water purification system, the level of contaminants must be carefully monitored. Conductivity and resistance are used to measure the purity of natural and ultrapure water respectively. Feed water is analysed by an assortment of direct chemical means to determine the necessary system filtration steps. In general, high quality water can be produced by combined reverse osmosis and electrodeionization of treated tap water. Processed water is supplied to an ultrapure water system to provide final polished water. A detailed water processing protocol is presented along with quality assurance guidelines to ensure the consistent production of high quality ultrapure water suitable for in-vitro human embryo culture. 相似文献
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G. Wiemer U. Hellwich A. Wellstein J. Dietz M. Hellwich D. Palm 《Naunyn-Schmiedeberg's archives of pharmacology》1982,321(4):239-246
Summary In reticulocyte-rich suspensions of red blood cells from rats extrusion of cAMP as a regulatory mechanism of intracellular cAMP was investigated.In response to isoprenaline and/or the phosphodiesterase inhibitors Ro 20-1724 and rolipram extrusion of cAMP increases dependent on the concentration of the drugs and time of exposure. However, these drugs exert their effects on the extrusion of cAMP only indirectly, i.e. via increased intracellular levels of cAMP, since the respective EC50-values of the drugs for intracellular accumulation and extrusion of cAMP are identical (isoprenaline: 50 nM; rolipram: 1 M; Ro 20-1724: 15 M).The dependence of the rate of extrusion on intracellular levels of cAMP is characterized by a typical concentration-effect relationship from which a maximal capacity of cAMP extrusion of 3–6 nmol/10 min/109 cells and a half maximal effective intracellular cAMP concentration of 40–50 nmol/109 cells can be derived. This relationship has been inferred from either kinetic or steady-state approaches. At rapidly changing intracellular levels of cAMP an apparent time lag of extracellular cAMP accumulation is obligatorily conditioned by this relationship. Vasodilating drugs which lower the ATP content of the cells as well as the uncoupler of oxidative phosphorylation, FCCP, inhibit the extrusive process (papaverine > FCCP > dipyridamole > dilazep hexobendine carbocromene) leading to a 3–5-fold increase of the intrato extracellular concentration gradient of cAMP.It is concluded that extrusion of cAMP is a saturable and energy-dependent process which regulates the intracellular cAMP concentration independent of the activities of adenylate cyclase and phosphodiesterase.This work was supported by a grant from the Deutsche Forschungsgemeinschaft 相似文献
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We have investigated the effects of mechanical elution of neutrophils from nylon-wool fiber (NWF) using the scanning electron microscope and biochemical analysis of elution fractions. We have determined that mechanical removal of neutrophils from nylon-wool fiber disrupts neutrophils adherent to nylon-wool fiber and augments release of granules, release of peripheral cytoplasmic fragments, and release of lactic dehydrogenase, a soluble cytoplasmic enzyme. Mechanical shearing of the adherent cell, and not adherence per se, causes the fragmentation. The extent of fragmentation is proportional to the NWF surface area available to neutrophils and is maximal at the temperature for optimal adherence and spreading. Agents that decrease cell spreading (n-ethylmaleimide and cold) diminish fragmentation. Cytochalasin B, an agent that destabilizes the neutrophil cortex, increases fragmentation. Fragmentation may be an important contributing cause of the abnormal morphology, function, and in vivo survival of nylon-wool-fiber procured human neutrophils. The prevention of fragmentation would appear to be necessary to insure the procurement of optimally functioning cells. Elution of NWF-adherent neutrophils in the cold might be a practical way to diminish neutrophil damage during clinical filtration leukapheresis. 相似文献
10.
Anne-Joy M de Graan Alex Sparreboom Peter de Bruijn Evert de Jonge Bronno van der Holt Erik A C Wiemer Jaap Verweij Ron H J Mathijssen Ron H N van Schaik 《British journal of clinical pharmacology》2015,80(3):560-568