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101.
Hristov KL Cui X Brown SM Liu L Kellett WF Petkov GV 《American journal of physiology. Cell physiology》2008,295(5):C1344-C1353
We investigated the role of large-conductance Ca(2+)-activated K(+) (BK) channels in beta3-adrenoceptor (beta3-AR)-induced relaxation in rat urinary bladder smooth muscle (UBSM). BRL 37344, a specific beta3-AR agonist, inhibits spontaneous contractions of isolated UBSM strips. SR59230A, a specific beta3-AR antagonist, and H89, a PKA inhibitor, reduced the inhibitory effect of BRL 37344. Iberiotoxin, a specific BK channel inhibitor, shifts the BRL 37344 concentration response curves for contraction amplitude, net muscle force, and tone to the right. Freshly dispersed UBSM cells and the perforated mode of the patch-clamp technique were used to determine further the role of beta3-AR stimulation by BRL 37344 on BK channel activity. BRL 37344 increased spontaneous, transient, outward BK current (STOC) frequency by 46.0 +/- 20.1%. In whole cell mode at a holding potential of V(h) = 0 mV, the single BK channel amplitude was 5.17 +/- 0.28 pA, whereas in the presence of BRL 37344, it was 5.55 +/- 0.41 pA. The BK channel open probability was also unchanged. In the presence of ryanodine and nifedipine, the current-voltage relationship in response to depolarization steps in the presence and absence of BRL 37344 was identical. In current-clamp mode, BRL 37344 caused membrane potential hyperpolarization from -26.1 +/- 2.1 mV (control) to -29.0 +/- 2.2 mV. The BRL 37344-induced hyperpolarization was eliminated by application of iberiotoxin, tetraethylammonium or ryanodine. The data indicate that stimulation of beta3-AR relaxes rat UBSM by increasing the BK channel STOC frequency, which causes membrane hyperpolarization and thus relaxation. 相似文献
102.
Motion detection, noise reduction, texture suppression, and contour enhancement by spatiotemporal Gabor filters with surround inhibition 总被引:2,自引:0,他引:2
We study the orientation and speed tuning properties of spatiotemporal three-dimensional (3D) Gabor and motion energy filters as models of time-dependent receptive fields of simple and complex cells in the primary visual cortex (V1). We augment the motion energy operator with surround suppression to model the inhibitory effect of stimuli outside the classical receptive field. We show that spatiotemporal integration and surround suppression lead to substantial noise reduction. We propose an effective and straightforward motion detection computation that uses the population code of a set of motion energy filters tuned to different velocities. We also show that surround inhibition leads to suppression of texture and thus improves the visibility of object contours and facilitates figure/ground segregation and the detection and recognition of objects. 相似文献
103.
Ana PM Oliveira Rosana Gentile Arnaldo Maldonado Júnior Eduardo J Lopes Torres Silvana C Thiengo 《Memórias do Instituto Oswaldo Cruz》2015,110(6):739-744
The aim of this study was to analyse the infection dynamics ofAngiostrongylus
cantonensis in its possible intermediate hosts over two years in an urban
area in the state of Rio de Janeiro where the presence ofA.
cantonensis had been previously recorded in molluscs. Four of the seven
mollusc species found in the study were exotic.Bradybaena similaris
was the most abundant, followed byAchatina fulica,
Streptaxis sp., Subulina octona,
Bulimulus tenuissimus, Sarasinula linguaeformis
and Leptinaria unilamellata. Only A. fulica
and B. similaris were parasitised by A.
cantonensis and both presented co-infection with other helminths. The
prevalence of A. cantonensisin A. fulica was more
than 50% throughout the study. There was an inverse correlation between the
population size ofA. fulica and the prevalence of A.
cantonensis and abundance of the latter was negatively related to
rainfall. The overall prevalence of A. cantonensis in B.
similariswas 24.6%. A. fulica was the most important
intermediary host of A. cantonensis in the studied area
andB. similaris was secondary in importance for A.
cantonensis transmission dynamics. 相似文献
104.
105.
To form a coherent percept of the environment, our brain combines information from different senses. Such multisensory integration occurs in higher association cortices; but supposedly, it also occurs in early sensory areas. Confirming the latter hypothesis, we unequivocally demonstrate supra-additive integration of touch and sound stimulation at the second stage of the auditory cortex. Using high-resolution fMRI of the macaque monkey, we quantified the integration of auditory broad-band noise and tactile stimulation of hand and foot in anaesthetized animals. Integration was found posterior to and along the lateral side of the primary auditory cortex in the caudal auditory belt. Integration was stronger for temporally coincident stimuli and obeyed the principle of inverse effectiveness: greater enhancement for less effective stimuli. These findings demonstrates that multisensory integration occurs early and close to primary sensory areas and--because it occurs in anaesthetized animals--suggests that this integration is mediated by preattentive bottom-up mechanisms. 相似文献
106.
Models of rheumatoid arthritis (RA) in laboratory animals are important tools for research into pathogenic mechanisms and
the development of effective, safe therapies. Rodent models (rats and mice) have provided important information about the
pathogenic mechanisms. However, the evolutionary distance between rodents and humans hampers the translation of scientific
principles into effective therapies. The impact of the genetic distance between the species is especially seen with treatments
based on biological molecules, which are usually species-specific. The outbred nature and the closer anatomical, genetic,
microbiological, physiological, and immunological similarity of nonhuman primates to humans may help to bridge the wide gap
between inbred rodent strain models and the heterogeneous RA patient population. Here we review clinical, immunological and
pathological aspects of the rhesus monkey model of collagen-induced arthritis, which has emerged as a reproducible model of
human RA in nonhuman primates. 相似文献
107.
108.
Summary The hydrazide derivative of polyacrylate-coated glass was used for the immobilization of glucose oxidase (GO) from Penicillium vitale after periodate oxidation of its carbohydrate moiety. Periodate oxidation of the carbohydrate residues did not influence catalytic activity of the enzyme. Immobilized GO is extremely stable both at 4°C and 25°C for extended period. 相似文献
109.
Ernesta Malinauskyte Paul A. Cornwell Louise Reay Neil Shaw Jordan Petkov 《Biopolymers》2020,111(11):e23401
Hair proteins are significantly affected by environmental pH. This impact tends to increase with prior hair damage. To understand how pH affects bleached hair properties, we utilized a number of techniques allowing for the determination of hair thermal properties, swelling and water sorption, and dry and wet tensile properties. At pH 5, hair proteins had the best structural integrity, as determined by differential scanning calorimetry and the highest tensile modulus. At pH 10, protein cross-linking density decreased, water content and hair cross-sectional diameter increased. Alkaline treatment, when compared with pH 5, did not reduce intermediate filament conditions (evaluated via enthalpy measurement) nor mechanical property performance in the wet state. In contrast to alkaline-treated hair, bleached hair equilibrated at pH 3 behaved very differently: it contained two different crosslink density zones, was the least stiff in dry and stiffest in wet conditions. Additionally, it absorbed less water and had the lowest diameter because of reduced water binding by protonated carboxyl groups. The pH 3 to 10 did not affect the mechanical strength of bleached hair in dry or wet conditions. 相似文献
110.