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Amphetamine significantly attenuated neural excitation, which was indexed by the onset of a myoclonic seizure, in young mice genetically predisposed to high levels of neural excitation and motor activity, whereas it increased excitation in mature mice of the same genetic stock. Apomorphine simulated the effects of amphetamine while clonidine did not. Consequently, it appears that a dopaminergic mechanism, which subsequently undergoes a developmental alteration, is mediating the paradoxical antiexcitatory effect of amphetamine. 相似文献
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Various types of experimental hyperlactatemia were induced in the normal anesthetized dog, and the changes in insulin secretion were measured in the pancreatico-duodenal vein. Hyperlactatemia was induced in the absence or in the presence of an infusion of sodium dichloroacetate (DCA), which activates pyruvate dehydrogenase. 1. Exogenous hyperlactatemia: The infusion of sodium L(+)lactate resulted in a strong increase in blood lactate level which was accompanied by a significant increase in the insulin output from the pancreatico-duodenal vein. The administration of DCA did not counteract the increase in lactate level and did not modify insulin output either. 2. Endogenous hyperlactatemia: This was induced either by pharmacological means: the subcutaneous injection of an antidiabetic biguanide, phenformin (20 mg/kg), or by physiological means: intense muscular work. In both cases an increase in the lactate level and in insulin output was recorded. The administration of DCA suppressed the hyperlactatemia and counteracted the increase in insulin output. These results show that there is a relationship between lactate level and insulin secretion, and give evidence for a role of endogenous lactate in the regulation of insulin secretion. 相似文献
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Cryptosporidium spp. in domestic dogs: the "dog" genotype 总被引:3,自引:0,他引:3
Morgan UM Xiao L Monis P Fall A Irwin PJ Fayer R Denholm KM Limor J Lal A Thompson RC 《Applied and environmental microbiology》2000,66(5):2220-2223
Genetic and phylogenetic characterization of Cryptosporidium isolates at two loci (18S rRNA gene and heat shock gene) from both Australian and United States dogs demonstrated that dog-derived Cryptosporidium isolates had a distinct genotype which is conserved across geographic areas. Phylogenetic analysis provided support for the idea that the "dog" genotype is, in fact, a valid species. 相似文献
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The influence of the two operator-like regions lying within or near the lac regulatory region on the binding of lac repressor to lac operator has been investigated. λdlac phages deleted either for the “second operator” in the beginning of the Z gene or deleted for the “third operator” at the end of the I gene were constructed. In in vitro binding experiments it could be shown that the deletion of secondary repressor binding sites from the lac regulatory region does not significantly alter the stability of the repressor—operator complex. Measuring the rate constant of association of repressor with operator in the presence of a 150-fold excess of unspecific DNA, we observed a concentration-dependent effect of the unspecific DNA, although the ratio of operator to non-operator DNA was kept constant. A small effect of the secondary binding sites is seen on the rate of association of repressor with operator, indicating that the secondary binding sites might play a role in facilitating association of repressor with operator under in vivo conditions. 相似文献
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Remijn GB Ito H Nakajima Y 《Journal of PHYSIOLOGICAL ANTHROPOLOGY and Applied Human Science》2004,23(6):243-247
Temporal aspects of the perceptual integration of audiovisual information were investigated by utilizing the visual "streaming-bouncing" phenomenon. When two identical visual objects move towards each other, coincide, and then move away from each other, the objects can either be seen as streaming past one another or bouncing off each other. Although the streaming percept is dominant, the bouncing percept can be induced by presenting an auditory stimulus during the visual coincidence of the moving objects. Here we show that the bounce-inducing effect of the auditory stimulus is paramount when its onset and offset occur in temporal proximity of the onset and offset of the period of visual coincidence of the moving objects. When the duration of the auditory stimulus exceeded this period, visual bouncing disappears. Implications for a temporal window of audiovisual integration and the design of effective audiovisual warning signals are discussed. 相似文献
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Y Har-Shai M Silbermann N D Reis C Zinman I Rubinstein Z Abassi O S Better 《Plastic and reconstructive surgery》1992,89(2):283-289
Visualization of the intramuscular microcirculation during and after compartmental syndrome was studied by microangiograms and histologic cross sections. A marked reduction in the circulation of the endomysial capillary network was found during compartment tamponade, whereas the perimysium arteriolar system was patent. Revascularization took place by formation of distorted blood vessels accompanied by intramuscular hematomas in muscles 7 and 14 days after the compartment insult. The cross sections show massive fibroblastic activity around blood vessels that caused concealed intramuscular pressure-ischemic contracture resulting in the foci of myofibrillar necrosis seen within normal muscle tissue. The muscle located in the tamponaded compartment profusely bleeds when it is touched, even though its viability is in doubt. The explanation for this clinical observation might be the abnormal intramuscular revascularization that was found in this work. 相似文献
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A C Jackson M Tabrizi M I Kotlikoff J R Voss 《Journal of applied physiology (Bethesda, Md. : 1985)》1984,57(4):1223-1230
A computer model of the mechanical properties of the dog respiratory system based on the asymmetrically branching airway model of Horsfield et al. (11) is described. The peripheral ends of this airway model were terminated by a lumped-parameter impedance representing gas compression in the alveoli, and lung and chest wall tissue properties were derived from measurements made in this laboratory. Using this model we predicted the respiratory system impedance and the distribution of pressures along the airways in the dog lung. Predicted total respiratory system impedances for frequencies between 4 and 64 Hz at three lung volumes were found to compare quite closely to measured impedances in dogs. Serial pressure distributions were found to be frequency-dependent and to result in higher pressures in the lung periphery than at the airway opening at some frequencies. The implications of this finding for high-frequency ventilation are discussed. 相似文献
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Francoise Vignaux Christophe Hitte Catherine Priat Jean-Claude Chuat Catherine Andre Francis Galibert 《Mammalian genome》1999,10(9):888-894
A dog whole-genome radiation hybrid (WGRH) panel including 126 clones was constructed by fusing dog fibroblasts irradiated
at 5000 rads with thymidine kinase-deficient hamster cells. The average retention frequency of the panel designated as RHDF5000
is 21%, and its resolution power is estimated at 600 kb. The data provided by typing 400 markers were used to estimate linkage
power changes subsequent to panel reduction. These changes were analyzed by recomputing typing data from five reduced panels.
From these simulations, the parameters allowing investigation of the evolution of the linkage power in the course of panel
reduction were determined. Guidelines for constructing a WGRH panel are proposed.
Received: 23 February 1999 / Accepted: 11 May 1999 相似文献
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