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91.
The dispensable N-terminus of iso-1-cytochrome c (iso-1) in the yeast Saccharomyces cerevisiae was replaced by 11 different amphipathic structures. Rapid degradation of the corresponding iso-1 occurred, with the degree of degradation increasing with the amphipathic moments; and this amphipathic-dependent degradation was designated ADD. ADD occurred with the holo-forms in the mitochondria but not as the apo-forms in the cytosol. The extreme mutant type degraded with a half-life of approximately 12 min, whereas the normal iso-1 was stable over hours. ADD was influenced by the +/– state and by numerous chromosomal genes. Most importantly, ADD appeared to be specifically suppressed to various extents by deletions of any of the YME1, AFG3, or RCA1 genes encoding membrane-associated mitochondrial proteases, probably because the amphipathic structures caused a stronger association with the mitochondrial inner membrane and its associated proteases. The use of ADD assisted in the differentiation of substrates of different mitochondrial degradation pathways. 相似文献
92.
Hyperbaric oxygenation mitigates focal cerebral injury and reduces striatal dopamine release in a rat model of transient middle cerebral artery occlusion 总被引:16,自引:0,他引:16
Yang ZJ Camporesi C Yang X Wang J Bosco G Lok J Gorji R Schelper RL Camporesi EM 《European journal of applied physiology》2002,87(2):101-107
The usefulness of the administration of hyperbaric oxygen (HBO) in the treatment of acute focal cerebral ischemia remains
debatable. A significant association exists between focal cerebral injury and an excessive release of extracellular dopamine
(DA). In vivo microdialysis was used in the present study to examine the effect of HBO on DA release in the striatum during
ischemia and reperfusion in rats. The histological changes occurring were also evaluated. Focal cerebral ischemia was induced
by occlusion of the middle cerebral artery (MCA) using a surgically placed intraluminal filament. Control rats (n=8) were subjected to 1 h of ischemia, whilst the study rats (n=8) were in addition treated with HBO (2.8 atmospheres of absolute pressure 100% O2) during ischemia. Both groups were returned to breathing room air at normal pressure during reperfusion. Microdialysis samples
were continuously collected at 15 min intervals at 2 μl·min–1. The [mean (SE)] increase in release of striatal DA attained significance after 30 min of occlusion of MCA [170 (24)%], and
continued to increase [268 (26)% at 45 min] reaching a peak level at 60 min [672 (59)%] before returning to the baseline level
during the late reperfusion phase. There was no significant change in the level of DA in HBO treated rats during the period
of ischemia. A significant reduction in edema and neuronal shrinkage were observed by histological examination in HBO treated
rats when compared to the control rats. The results showed that HBO, when administered during ischemia, offered significant
neuroprotection in our experimental model of transient focal cerebral ischemia in the rat. The mechanism seems to imply, at
least in part, a reduced level of DA.
Electronic Publication 相似文献
93.
Mature T cells residing in peripheral lymphoid organs have frequent contact with antigen presenting cells (APC). Such contact may be required for T cell survival, but the degree to which signals in mature T cells are induced by TCR recognition of self peptide/MHC complexes is unclear. We have used induction of the early growth response gene 1 (Egr1) as an indicator of signal transduction in 3.L2 (I-Ek-restricted) T cells interacting with APC in the absence of exogenous antigen. The data show that Egr1 can be induced in 3.L2 T cells by TCR recognition of self peptides presented by I-Ek. However, a more transient induction of Egr1 can be induced in 3.L2 T cells interacting with dendritic cells derived from class II/beta2m double-deficient mice. Egr1 induction after T cell-APC contact was also observed in a freshly isolated polyclonal CD4 T cell population. The data suggest that self peptide/MHC recognition by the TCR induces a signal in T cells and that dendritic cells can also induce a more transient T cell signal by an MHC-independent mechanism. 相似文献
94.
心理弹性(resilience)研究综述 总被引:23,自引:1,他引:23
弹性(resilience)日益为心理学界所关注,已经成为心理学的一个重要研究领域。文章追溯了弹性研究的渊源,介绍了众多研究者对于弹性的认识,回顾了弹性领域研究的进展情况,对以往的研究进行了评价,对以后的研究进行了展望。 相似文献
95.
Paolo Cerretelli Bruno Grassi Lei Xi Federico Schena Claudio Marconi Michael Meyer Guido Ferretti 《European journal of applied physiology》1995,71(4):287-294
To gain an insight into the origin of the phase I ventilatory response to exercise (ph I) in humans, pulmonary ventilation WE) and end-tidal partial pressures of oxygen and carbon dioxide (P
ETO2 and P
ETCO2, respectively) were measured breath-by-breath in six male subjects during constant-intensity exercise on the cycle ergometer at 50, 100 and 150 W, with eupnoeic normocapnia (N) or hyperpnoeic hypocapnia (H) established prior to the exercise test. Cardiac output (Q2) was also determined beat-by-beat by impedance cardiography on eight subjects during moderate exercise (50 W), and the C02 flow to the lungs (Q2·CvCO2 where CvCO2 is concentration of CO2 in mixed veneous blood) was estimated with a time resolution of one breathing cycle. In N, the initial abrupt increase of PE during ph I (VE approximately 18 l · min–1 above rest) was followed by a transient fall. When P
ETCO2 started to increase (and P
ETO2 decreased) VE increased again (phase II ventilatory response, ph II). In H, during ph I VE was similar to that of N. By contrast, during ph II VE kept gradually decreasing and started to increase only when P
ETCO2 had returned to approximately 40 mmHg (5.3 kPa). Thus, as a result of the prevailing initial conditions (N or H) a temporal shift of the time-course of VE during ph II became apparent. No correlation was found between C02 flow to the lungs and VE during ph I. These results are interpreted as suggesting that an increased C02 flow to the lungs does not constitute an important factor for the initial hyperventilatory response to exercise. They are rather compatible with a neural origin of ph I, and would support the neurohumoral theory of ventilatory control during exercise. 相似文献
96.
冠状病毒是所有RNA病毒中基因组最大的病毒,具有胃肠道、呼吸道或神经系统嗜性,常引起人普通感冒或动物胃肠道、呼吸系统疾病,而SARS-CoV则引起人的严重急性呼吸道综合征。研究冠状病毒分子生物学特征对阐明其病毒粒子的发生、感染和致病机制有重要意义。本文就冠状病毒的分子生物学特征包括冠状病毒基因组特征,编码蛋白的结构及功能等方面的研究进展作一综述。 相似文献
97.
Although Hedgehog (HH) signaling plays a critical role in patterning the ventral midbrain, its role in early midbrain specification is not known. We examined the midbrains of sonic hedgehog (Shh) and smoothened (Smo) mutant mice where HH signaling is respectively attenuated and eliminated. We show that some ventral (Evx1+) cell fates are specified in the Shh-/- mouse in a Ptc1- and Gli1-independent manner. HH-independent ventral midbrain induction was further confirmed by the presence of a Pax7-negative ventral midbrain territory in both Shh-/- and Smo-/- mice at and before embryonic day (E) 8.5. Midbrain signaling centers are severely disrupted in the Shh-/- mutant. Interestingly, dorsal markers are up-regulated (Wnt1, Gdf7, Pax7), down-regulated (Lfng), or otherwise altered (Zic1) in the Shh-/- midbrain. Together with the increased cell death seen specifically in Shh-/- dorsal midbrains (E8.5-E9), our results suggest specific regulation of dorsal patterning by SHH, rather than a simple deregulation due to its absence. 相似文献
98.
低频超声透皮给药的研究进展与应用 总被引:1,自引:0,他引:1
低频超声可以增强包括大分子药物在内的许多药物的透皮传输,其主要机制是超声的空化作用,大多数人认为是通过改变角质层角化细胞排列结构来提高皮肤渗透能力的.低频超声透皮给药已被人们用于离体实验和动物活体实验,到目前为止,无论是小分子透皮传输还是大分子透皮传输都有很多成功的例子.但是真正通过低频超声透皮导入药物进行治疗的临床应用报道很少,需要更进一步大量的临床试验以确定其安全性与实用价值.一旦其安全性得以证实,合适的低频超声透皮仪研制成功,低频超声快速透皮必将成为一种安全、有效、可控、经济的新型给药方式. 相似文献
99.
Incoronata Tritto San Xi Li Laura Boggioni Maria Carmela Sacchi Paolo Locatelli Aideen O'Neill 《Macromolecular chemistry and physics.》1997,198(5):1347-1361
Ethylene polymerizations and norbornene oligomerizations catalysed by Cp2Ti13CH3Cl/MAO (Cp: cyclopentadienyl; MAO: methylaluminoxane) mixtures have been carried out at different temperatures (from -20°C to 20°C), in order to test the validity of carbene mechanisms in α-olefin polymerizations. Depending on the temperature, different ratios of the cationic species [Cp2Ti13CH3]+[Cl · MAO]? and precursors of the alkylidene Cp2Ti = 13CH2 exist. The in situ polymerization of 13C enriched ethylene was monitored by 13C NMR spectroscopy. Moreover, catalytic activity was determined and polyethylene samples were analyzed by 13C NMR and gel permeation chromatography (GPC). The following evidence has been provided against the carbene mechanism in the α-olefin polymerization with titanocene based catalysts: (a) in the in situ ethylene polymerization experiments the appearance of polyethylene signals is concurrent with the decrease of cationic [Cp2Ti13CH3]+[Cl · MAO]? signals and is not related to the intensity of the alkylidene Cp2Ti = 13CH2 signals; (b) from the 13C NMR analysis of polyethylene chain-end groups the 13C enrichment of Cp2Ti13CH3Cl has only been found in the methyl chain-end group and not in the methylene of the propyl chain-end group, as should have been the case if the carbene mechanism had been valid; (c) from norbornene oligomerization (at 0°C) the addition product 2-13C enriched methyl-norbornane has been identified. Moreover, the identification of a 13C enriched methylidene-norbornane dimer at higher temperatures has revealed the possibility of norbornene addition to titanium carbenes through the formation of titanacyclobutane without the opening of the norbornene ring. However, this process requires higher energies with respect to the Cossee type insertion. 相似文献
100.
汉区少数民族学生文化疏离感研究 总被引:2,自引:0,他引:2
目的:提出文化疏离感的操作性定义和初步的理论构想,为我国少数民族的文化认同和文化适应,以及少数民族青少年的教育培养提供比较重要的参考资料,为疏离感理论的丰富起到一定积极作用.方法:自编<汉区少数民族学生文化疏离感量表>,进行信效度考察以后对678名汉区少数民族学生进行调查.结果:1.文化疏离感及其四个子维度在地区主效应上均表现出显著差异,在年龄主效应上差异不显著;文化分离感和不和谐感在性别主效应上差异显著.2.文化疏离感及其两个子维度(文化孤立感和文化分离感)在年龄和地区,以及在年龄、地区和性别的交互作用上均表现出显著差异.3.影响文化疏离感及其文化孤立感、文化分离感、被控感三个维度的主要变量是学生小学前后居住地区的改变,而影响不和谐感的主要变量是性别.结论:小学前后居住地的改变会影响少数民族学生文化疏离感. 相似文献