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排序方式: 共有119条查询结果,搜索用时 250 毫秒
81.
The genetic variability of the gonochoric Leptestheria dahalacensis (Rüppel, 1837) was studied through the analysis of mitochondrial and nuclear (microsatellite loci) markers in eight Italian and two Central European populations. Mitochondrial data exhibited a low variability, as only six mitotypes were scored: five in Italy and one for both Central European samples, with a very low number of substitutions. All analysed microsatellite loci were variable, with 3–5 alleles per locus and 1–4 alleles per population. All populations were at the Hardy–Weinberg equilibrium, with the exceptions of two samples for locus ldAC-16, due to heterozygote excess, and of four populations for locus ldAC-11, probably linked to the presence of null alleles. A substantial population structuring was found between Central European and Italian samples for both utilized markers. This observation may be explained by isolation by distance and/or recent isolation events. On the other hand, the absence of a clear inter-pond variability in Italian sample comparisons may be ascribed to high dispersal ability in the short range. Handling editor: K. Martens  相似文献   
82.
Presence of functional TLR2 and TLR4 on human adipocytes   总被引:2,自引:2,他引:0  
In addition to the well-known role of adipose tissue in energy metabolism, it has recently been demonstrated that this tissue can secrete a large array of molecules, including inflammatory cytokines. Furthermore, recent studies suggest that adipose cells can behave as immune cells. Therefore, the aim of this study was to determine the presence of the two most prominent ‘pattern recognition receptors’ for bacterial and fungal cell wall components, TLR2 and TLR4 on human adipose cells, as well as to assess their functionality. We demonstrated that TLR2 and TLR4 were expressed at relatively high levels (compared to a monocyte cell line) on the surface of human adipose cells. Stimulation of human adipocytes with lipopolysaccharide (LPS), or with lipoteichoic acid (LTA), two specific ligands of TLR4 and TLR2, respectively, induced a strong increase in TNFα production. The specificity of the response was demonstrated by the use of anti-TLR4 and anti-TLR2 blocking antibodies, which were able to decrease LPS- or LTA-induced TNFα secretion. Thus, it is clear that these receptors are functional in human adipocytes. This study adds weight to the argument that human fat tissue plays a potential role in innate immunity. Sandrine Bés-Houtmann, Régis Roche, Christian Lefebvre d’Hellencourt and Maya Cesari have contributed equally to this work.  相似文献   
83.
A series of 4-amino-5-vinyl-3(2H)-pyridazinones and analogues were synthesized and their antinociceptive effect was evaluated in the mouse abdominal constriction model. Several of the novel compounds showed ED(50) values in the range 6-20mg/kg/sc and demonstrated to be able to completely protect all the treated animals from the effect of the noxious stimulus at 30 mg/kg/sc. SAR studies confirmed the essential role played by an amino or substituted amino function at position 4 and by a vinyl group at position 5 of the diazine system.  相似文献   
84.
The estimation of the time of exposure of a picture portraying an action increases as a function of the amount of movement implied in the action represented. This effect suggests that the perceiver creates an internal embodiment of the action observed as if internally simulating the entire movement sequence. Little is known however about the timing accuracy of these internal action simulations, specifically whether they are affected by the level of familiarity and experience that the observer has of the action. In this study we asked professional pianists to reproduce different durations of exposure (shorter or longer than one second) of visual displays both specific (a hand in piano-playing action) and non-specific to their domain of expertise (a hand in finger-thumb opposition and scrambled-pixels) and compared their performance with non-pianists. Pianists outperformed non-pianists independently of the time of exposure of the stimuli; remarkably the group difference was particularly magnified by the pianists’ enhanced accuracy and stability only when observing the hand in the act of playing the piano. These results for the first time provide evidence that through musical training, pianists create a selective and self-determined dynamic internal representation of an observed movement that allows them to estimate precisely its temporal duration.  相似文献   
85.
Abstract. The ultrastructure of the male gonad of Eulimnadia texana (Branchiopoda, Spinicaudata) has been observed for the first time to investigate the sexuality of a well-studied case of androdioecy in the animal kingdom. The male gonad is a double structure located in the hemocoel throughout the entire body length on each side of the midgut. Male gametes originate from the wall and mature centripetally toward the lumen; the proliferative activity is very high and continuous and therefore the mature gonad is full of numerous germ cells. Inside the lumen several degenerative stages are found mixed with sperm cells and spermatids, the latter two being not easily distinguishable because of the slight differences between them. The evolutionary meaning of the degenerative process in E. texana male gametes is difficult to explain, and we propose some hypotheses about its possible role or cause in the studied population: (a) to help build spermatophores, (b) to act as a trophic component for viable sperm, (c) as a manifestation of inbreeding depression, and/or (d) to regulate the number of sperm cells.  相似文献   
86.
Ten fragments of a wood-inhabiting polypore were found in the early Neolithic village of ‘La Marmotta’ (Anguillara Sabazia, Rome), formerly located on the shore of the Bracciano Lake. Five of these were found in three different huts, and two outside near other structures. Some fragments of the partly degraded specimens were used for DNA sequencing in order to the identity of the fungus, which proved to be Daedaleopsis tricolor. Pharmacological aspects of this and other previously discovered prehistoric polypores are also noted.  相似文献   
87.
88.
Amphetamines are a group of sympathomimetic drugs that exhibit strong central nervous system stimulant effects. d-Amphetamine ((+)-alpha-methylphenetylamine) is the parent drug in this class to which all others are structurally related. In drug discovery, d-amphetamine is extensively used either for the exploration of novel mechanisms involving the catecholaminergic system, or for the validation of new behavioural animal models. Due to this extensive use of d-amphetamine in drug research and its interest in toxicologic–forensic investigation, a specific and high-throughput method, with minimal sample preparation, is necessary for routine analysis of d-amphetamine in biological samples. We propose here a sensitive, specific and high-throughput bioanalytical method for the quantitative determination of d-amphetamine in rat blood using MS3 scan mode on a hybrid triple quadrupole-linear ion trap mass spectrometer (LC–MS/MS/MS). Blood samples, following dilution with water, were prepared by fully automated protein precipitation with acetonitrile containing an internal standard. The chromatographic separation was achieved on a Waters XTerra C18 column (2.1 mm × 30 mm, 3.5 μm) using gradient elution at a flow rate of 1.0 mL/min over a 2 min run time. An Applied Biosystems API4000 QTRAP™ mass spectrometer equipped with turbo ion-spray ionization source was operated simultaneously in MS3 scan mode for the d-amphetamine and in multiple reaction monitoring (MRM) for the internal standard. The MS/MS/MS ion transition monitored was m/z 136.1 → 119.1 → 91.1 for the quantitation of d-amphetamine and for the internal standard (rolipram) the MS/MS ion transition monitored was m/z 276.1 → 208.2. The linear dynamic range was established over the concentration range 0.5–1000 ng/mL (r2 = 0.9991). The method was rugged and sensitive with a lower limit of quantification (LLOQ) of 0.5 ng/mL. All the validation data, such as accuracy, precision, and inter-day repeatability, were within the required limits. This method was successfully applied to evaluate the pharmacokinetics of d-amphetamine in rat. On a more general extent, this work demonstrated that the selectivity of the fragmentation pathway (MS3) can be used as alternative approach to significantly improve detection capability in complex situation (e.g., small molecules in complex matrices) rather than increasing time for sample preparation and chromatographic separation.  相似文献   
89.
Whole seminal plasma (SP) enhances the function and fertility of frozen/thawed ram sperm. The objective of the current study was to investigate whether SP proteins capable of binding to molecules from the sperm plasma membrane were conserved among ram breeds, and whether these proteins were sufficient to overcome cryopreservation-induced reductions in sperm quality. Whole ram SP, obtained from rams of various breeds, improved progressive motility of frozen/thawed sperm at all times evaluated (P < 0.05); however, it did not improve total motility (15 min, P = 0.480; 30 min, P = 0.764; and 45 min, P = 0.795). To identify SP proteins responsible for this effect, a new method was developed to retain SP proteins that bound specifically to the sperm membrane by immobilization of sperm membrane proteins. These proteins specifically bound to the sperm surface, especially the acrosomal region. Lactotransferrin, epididymal secretory protein E1, Synaptosomal-associated protein 29, and RSVP-20 were identified (mass spectrometry) in this fraction. The retained SP proteins fraction repaired ultrastructural damage of frozen/thawed sperm and, with the addition of fructose, significantly improved motility of frozen/thawed sperm. We concluded that SP proteins that bound to the sperm membrane were conserved among ram breeds, and that when added to frozen/thawed semen (along with an energy source), they repaired ram sperm damage and enhanced sperm motility.  相似文献   
90.
Abstract

A new contribution to the knowledge of Laboulbeniales (Ascomycetes) parasitic on Italian Staphylinidae (Insecta, Coleoptera).—Two new Laboulbeniales occurring on Italian Staphylinidae are described: Camptomyces europaeus, parasitic on Astenus thoracicus Baudi (Paederinae) and Corethromyces sardous, parasitic on Pseudobium labile (Er.) (Paederinae). Furthermore, the following species are reported for the first time in Italy: Compsomyces verticillatus (Thaxt.), Haplomyces texanus Thaxt., Smeringomyces anomalus (Thaxt.) and Teratomyces actobii Thaxt.  相似文献   
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