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排序方式: 共有4625条查询结果,搜索用时 31 毫秒
41.
C. Bizet C. Barreau C. Harmant M. Nowakowski A. Pietfroid 《Research in microbiology》1997,148(9):799-809
The “Biotype-100” identification system (BioMérieux, La Balme-les-Grottes, France) based on carbon source utilization was evaluated for its ability to discriminate among 10 species of Rhodococcus, 7 species of Gordona and one species of Dietzia. The type strains of three species of Tsukamurella and 8 species of Nocardia were also included in the study. Results were compared with chemotaxonomic and conventional data. Carbon source utilization was shown to be reliable, rapid and easy to use when compared with standard identification methods. The 29 species tested were unambiguously separated by carbon source utilization tests. Rhodococcus equi was found to be heterogenous.Les galeries “Biotype-100” (BioMérieux) ont été utilisées pour différencier 10 espèces du genre Rhodococcus, 7 espèces du genre Gordona et 1 espèce du genre Dietzia entre elles. Les souchestypes de 3 espèces du genre Tsukamurella et 8 espèces du genre Nocardia ont été incluses dans cette étude. Les résultats ont été comparés avec ceux des études chimiotaxonomiques et ceux obtenus avec les galeries d'identification classiques. Les galeries Biotype-100 sont sûres, rapides et faciles à utiliser par rapport aux galeries classiques. Les 29 espèces étudiées ont été identifiées sans aucune difficulté. L'espèce Rhodococcus equi s'est révélée hétérogène. 相似文献
42.
Three different auditory stimulus paradigms were used to elicit P300 potentials. Normal subjects were tested on the classical rare target stimulus, single-stimulus and omitted-stimulus conditions. Noninvasive identification of the cerebral sources of the event-related potentials (ERPs) was performed using spatio-temporal multiple dipole modeling (BESA software) with individually sized spherical head models. The grand average data of each condition was first independently modeled and these models were used as starting values for modeling each individual subject's data. Models for the rare-stimulus condition and single-stimulus condition both consisted of 6 dipoles. Models for the omitted-stimulus condition consisted of 2 dipoles. The dipole locations of the final individual 6-dipole models for the rare and single-stimulus conditions did not differ significantly from each other or from one previous result obtained from a another group of subjects (Tarkka et al. 1995). Super-imposition of the dipole coordinates on the sterotaxic brain atlas suggests that bilateral deep medial temporal lobe structures are the major contributors to rare and single-stimulus P300s. Because both the wave form morphology and the source model of the P300 elicited by single stimulus were close to those of the rare-stimulus P300 it may be that the underlying neural mechanisms eliciting these P300 potentials are essentially the same. 相似文献
43.
Several alternative algorithms for computer-assisted derivationof measurements of movement characteristics from manually reconstructedtracks of progressively motile human spermatozoa were compared.Fifty tracks were reconstructed at 30 Hz from video recordingsand analysed using traditional manual methods and by four combinationsof computer algo rithms. The best algorithm set was identified(Video-mot.mdpt) and the values for the curvilinear,average path and linear velocities (VCVL, VAVE and VLIN respectively),the amplitude of lateral displacement of the sperm head aboutthe axis of progression (AH) and the number of times the spermhead crossed the average path (the beat/cross frequency,BXF) obtained using it were compared to those obtained by manualanalysis. There was a considerable time saving when the computer-assistedmethod was used and the values it gave for the various movementcharacteristics showed good correspondence with those obtainedmanually. In addition, repeated data entry and analysis wasfound to be highly reproducible. When the tracks were re-plottedat 6 Hz (as used by the multiple-exposure photomicrography methodfor sperm motility analysis) insufficient information remainedin the tracks for reliable determination of anything other thanVLIN We conclude that the Videomot.mdpt program provides reliablevalues for the movement characteristics of progressively motilehuman spermatozoa, and believe it will be of great value inthe validation of commercial systems providing automated spermmovement analysis and in laboratories which do not have accessto such costly equipment. 相似文献
44.
Jorge A. Negroni Elena C. Lascano Ricardo H. Pichel 《Annals of biomedical engineering》1987,15(1):35-50
We undertook a theoretical analysis of the source resistance of the left ventricle represented in a mean pressure-mean flow
diagram, using the chamber properties established in terms of the pressure-volume relationship. This analysis showed that
pairs of points should lie above the linear function proposed by Elzinga and Westerhof. A third-order polynomial function
would theoretically explain better than a linear relation or a parabolic fit the curved shape of experimentally obtained
relationships. The analysis resolves the discrepancy between Elzinga and Westerhof's theoretical concept of linear source
resistance and the actual nonlinear
relationship. 相似文献
45.
Massimiliano Valeriani Domenico Restuccia Vincenzo Di Lazzaro Domenica Le Pera Carmen Barba Pietro Tonali François Mauguiere 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》1998,120(3):306-315
Brain electrical source analysis (BESA) of the scalp electroencephalographic activity is well adapted to distinguish neighbouring
cerebral generators precisely. Therefore, we performed dipolar source modelling in scalp medium nerve somatosensory evoked
potentials (SEPs) recorded at 1.5-Hz stimulation rate, where all the early components should be identifiable. We built a four-dipole
model, which was issued from the grand average, and applied it also to recordings from single individuals. Our model included
a dipole at the base of the skull and three other perirolandic dipoles. The first of the latter dipoles was tangentially oriented
and was active at the same latencies as the N20/P20 potential and, with opposite polarity, the P24/N24 response. The second
perirolandic dipole showed an initial peak of activity slightly earlier than that of the N20/P20 dipolar source and, later,
it was active at the same latency as the central P22 potential. Lastly, the third perirolandic dipole exaplaining the fronto-central
N30 potential scalp distribution was constantly more posterior than the first one. In order to evaluate the effect of an increasing
repetition frequency on the activity of SEP dipolar sources, we applied the model built from 1.5-Hz SEPs to traces recorded
at 3-Hz and 10-Hz repetition rates. We found that the 10-Hz stimulus frequency reduced selectively the later of the two activity
phases of the first perirolandic dipole. The decrement in strength of this dipolar source can be explained if we assume that:
(a) the later activity of the first perirolandic dipole can represent the inhibitory phase of a “primary response”; (b) two
different clusters of cells generate the opposite activities of the tangential perirolandic dipole. An additional finding
in our model was that two different perirolandic dipoles contribute to the centro-parietal N20 potential generation.
Received: 5 August 1997 / Accepted: 26 November 1997 相似文献
46.
Marchetti C Gallego MA Defossez A Formstecher P Marchetti P 《Human reproduction (Oxford, England)》2004,19(5):1127-1134
BACKGROUND: Detection of apoptosis in sperm samples may help evaluate sperm quality. Recently, it has been suggested that in some ejaculated sperm populations, apoptosis is caspase dependent. The aim of this study was to investigate the presence of activated caspases and examine possible correlations with apoptosis and sperm parameters in semen samples prepared for IVF. METHODS: To detect activated caspases, neat semen from infertile patients and sperm prepared by PureSperm gradient were stained with the fluorescein isothyocyanate-Val-Ala-Asp-fluoromethylketone (FITC-VAD-fmk) and analysed by flow cytometry. Cell death was determined by DNA fragmentation (TUNEL) and mitochondrial membrane potential. Sperm parameters were studied by conventional microscopy. RESULTS: FITC-VAD-fmk stained sperm cells in situ and the subcellular labeling pattern was compatible with the known localization of caspases. A significant correlation was found between the frequency of FITC-VAD-fmk stained cells and cell death markers. In both prepared sperm and neat semen a negative correlation was found between the percentage of FITC-VAD-fmk positive cells and standard parameters (concentration/motility). FITC-VAD-fmk positive cells negatively correlated with high fertilization rates after IVF. CONCLUSIONS: Labelling of sperm cells with the activated caspases-reacting fluorochrome provides a sensitive assay for detection of sperm apoptosis. This cytometric assay can be helpful to test sperm before IVF. 相似文献
47.
Fertilization, pregnancy and embryo implantation rates after ICSI in cases of obstructive and non-obstructive azoospermia 总被引:2,自引:0,他引:2
De Croo I Van der Elst J Everaert K De Sutter P Dhont M 《Human reproduction (Oxford, England)》2000,15(6):1383-1388
The aetiology of azoospermia can be grossly divided into obstructive and non-obstructive causes. Although in both cases testicular spermatozoa can be used to treat male fertility, it is not well established whether success rates following intracytoplasmic sperm injection (ICSI) are comparable. Therefore, a retrospective analysis of fertilization, pregnancy and embryo implantation rates was performed following ICSI with testicular spermatozoa in obstructive or non-obstructive azoospermia. In total, 193 ICSI cycles were carried out with freshly retrieved testicular spermatozoa; in 139 cases of obstructive and 54 cases of non-obstructive azoospermia. The fertilization rate after ICSI with testicular spermatozoa in non-obstructive azoospermia was significantly lower than in obstructive azoospermia (67.8% versus 74.5%; P = 0.0167). Within the non-obstructive group, the fertilization rate in the group of maturation arrest (47.0%) was significantly lower than in case of Sertoli cell-only (SCO) syndrome (71.2%) or germ cell hypoplasia (79. 5%). Embryo quality on day 2 after ICSI was similar for all groups. Pregnancy rates per transfer between obstructive (36.8%) and non-obstructive groups (36.7%) were similar. In cases of maturation arrest the pregnancy rate per transfer was lowest (20.0%) although not significantly different from SCO syndrome or hypoplasia groups. Embryo implantation rates were not different between the obstructive (19.6%) and non-obstructive groups (25.8%), and were lowest in cases of germ cell hypoplasia (15.8%). This retrospective analysis shows that although fertilization rate after ICSI with testicular spermatozoa in non-obstructive azoospermia is significantly lower than in obstructive azoospermia, pregnancy and embryo implantation rates are similar. 相似文献
48.
Differential RNA fingerprinting as a tool in the analysis of spermatozoal gene expression 总被引:9,自引:1,他引:9
Miller David; Tang Pei-Zhong; Skinner Clare; Lilford Richard 《Human reproduction (Oxford, England)》1994,9(5):864-869
The apparent decline in human male fertility and the concomitantincrease in testicular pathology have prompted discussion ofthe underlying molecular mechanisms which may underpin theseobservations. While monitoring the expression of protamlne-2genes in the human ejaculate, we found a representative complementof sperm mRNAs following sequence-independent amplificationof reverse-transcribed cDNAs with the polymerase chain reaction(RT-PCR). The revelation of unique sperm-derived PCR productsusing this method suggests that it should now be possible toinvestigate gene expression in human spermatogenesis by differentialRNA fingerprinting of ejaculate spermatozoa. The Identificationof molecular markers and the corresponding genes associatedwith male Infertility will be considerably enhanced by theseinvestigations while obviating the requirement for invasivebiopsy. 相似文献
49.
Localization of Somatosensory Evoked Potentials in Primary Somatosensory Cortex: A Comparison Between PCA and MUSIC 总被引:1,自引:0,他引:1
The aim of this study was to test source modeling strategies for EEC-data from a clinical group of amputees. The experimental conditions (measuring time, age and condition of the patients) resulted in low quality EEC-data. Noise reduction was achieved by a principal component analysis (PCA) and a multiple signal classification (MUSIC). A comparison of the results of these two methods with traditional signal handling yielded superior results for the MUSIC algorithm. 相似文献
50.
Induction of capacitation in human spermatozoa in vitro by an endometrial sialic acid-binding protein 总被引:2,自引:0,他引:2
A Ca2+-dependent sialic acid-binding protein (SABP) of humanendometrium, which specifically bound to human sperm head plasmamembrane in vitro, was found to increase the percentage motilityand acrosome-reacted pattern of uncapacitated spermatozoa. Theprotein was synthesized in the endometrium and secreted intothe uterine fluid. This intra-uterine factor, which is apparentlyadvantageous in vitro in inducing human sperm capacitation,may play a significant role in promoting the postrelease maturationof ejaculated spermatozoa by enhancing 45Ca uptake into spermatozoaby a pathway which is insensitive to calcium-channel blockers.However, the 45Ca uptake could be enhanced on exposure to thedivalent cation ionophore A23187 and inhibited in the presenceof the calmodulin inhibitor trifluoperazine. The SABP also inducesan increase in intracellular Ca2+ in spermatozoa, as seen byFURA-2 AM studies. Furthermore, overlay studies show human SABPto be a Ca2+-binding protein. The data presented here suggestthat SABP induces invitro sperm capacitation and the subsequentacrosome reaction by increasing intracellular Ca2+ concentration. 相似文献