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排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
Seeing the Light: Protein Theories of General Anesthesia 总被引:1,自引:0,他引:1
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Giedd Jay N.; Snell John W.; Lange Nicholas; Rajapakse Jagath C.; Casey B. J.; Kozuch Patricia L.; Vaituzis A. Catherine; Vauss Yolanda C.; Hamburger Susan D.; Kaysen Debra; Rapoport Judith L. 《Cerebral cortex (New York, N.Y. : 1991)》1996,6(4):551-559
Brain magnetic resonance images (MRI) of 104 healthy childrenand adolescents, aged 418, showed significant effectsof age and gender on brain morphometry. Males had larger cerebral(9%) and cerebellar (8%) volumes (P < 0.0001 and P = 0.008.respectively), which remained significant even after correctionfor height and weight After adjusting for cerebral size, theputamen and globus pallidus remained larger in males, whilerelative caudate size was larger in females. Neither cerebralnor cerebellar volume changed significantly across this agerange. Lateral ventricular volume increased significantly inmales (trend for females), with males showing an increase inslope after age 11. In males only, caudate and putamen decreasedwith age (P = 0.007 and 0.05, respectively). The left lateralventricles and putamen were significantly greater than the rightP = 0.01 and 0.0001, respectively). In contrast, the cerebralhemispheres and caudate showed a highly consistent right greater-than-leftasymmetry (P < 0.0001 for both). All volumes demonstrateda high degree of variability. These findings highlight gender-specificmaturational changes of the developing brain and the need forlarge gender-matched samples in pediatric neuropsychiatric studies. 相似文献
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Summary: We have developed a novel experimental model of cancer immunity in the frog, Xenopus , which may provide a useful alternative to murine tumor models and a way to assess whether the control of tumor development is a fundamental function of the immune system of vertebrates. In Xenoptis , tumor immunity can be studied in two developmentally distinct immune systems. The larval immune system reflects characteristics of an ancestral system that appears to function without classical MHC class I antigen presentation and an efficient effector mechanism. The adult system appears more highly evolved in that it is remarkably similar to that of mammals and is able to generate a potent antitumor response. This amphibian model also provides a unique system with which to investigate a postulated role of heat shock proteins as components of an ancestral system of antigen presentation and/or immune surveillance that predates the antigen presentation pathway that exclusively involves MHC molecules. 相似文献
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I. Nicholas Crispe 《Clinical & developmental immunology》1995,4(4):257-261
The hypothesis that prothymocytes are distinct from and regulated independently of
multilineage hemopoietic progenitors was tested by enumeration of these two cell populations
in normal versus congenitally athymic (nude) mice. The absence of a thymus and of
peripheral T cells in nude mice had no effect on the frequency of either multilineage
progenitors (day 12 CFU-S) or prothymocytes (CFU-T), suggesting that there is no feedback
regulation of CFU-T frequency. Thymus seeding from the bone marrow is therefore likely
to be regulated by the availability of niches for prothymocyte maturation, rather than by
feedback control of prothymocyte production. 相似文献
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Vasodepressor reactions after orthotopic cardiac transplantation: Relationship to reinnervation status 总被引:1,自引:0,他引:1
Nicholas J. Morgan-Hughes MB Rose Anne Kenny MD Christopher D. Scott MB John H. Dark MB Janet M. McComb MD 《Clinical autonomic research》1994,4(3):125-129
Ventricular vagal nerve endings are thought to trigger vasodepressor syncope. Reports of vasodepressor reactions associated with donor bradycardia after cardiac transplantation have led to speculation that vagal reinnervation occurs. We assessed reinnervation status in seven patients 23–36 months (median 24 months) post-transplantation. Heart rate responses to vagal manoeuvres (respiration, Valsalva) and sympathetic stimuli (exercise and injection of tyramine into the coronary artery supplying the sinus node) were measured. All patients underwent 60 min of 60° head-up tilt with foot plate support. During tilt four of the seven had vasodepressor reactions with a fall in mean arterial pressure of 20–90 mmHg. During vasodepression two patients had falls in donor heart rate of 13 and 40% relative to peak heart rate during tilt. These two patients had evidence of functional sympathetic reinnervation. By contrast the two patients without donor bradycardia during vasodepression had only limited or no evidence of sympathetic reinnervation. No patient had consistent evidence of parasympathetic reinnervation as judged by the heart rate response to vagal manoeuvres. Headup tilt can thus produce vasodepressor reactions with donor bradycardia after cardiac transplantation in the absence of consistent evidence of vagal reinnervation. Left ventricular nerve endings may not be the only mediators of tilt-induced vasodepressor reactions in man. Donor bradycardia during vasodepression may reflect sympathetic withdrawal and not vagal reinnervation. 相似文献