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81.
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Verkman AS Matthay MA Song Y 《American journal of physiology. Lung cellular and molecular physiology》2000,278(5):L867-L879
Fluid transport across epithelial and endothelial barriers occurs in the neonatal and adult lungs. Biophysical measurements in the intact lung and cell isolates have indicated that osmotic water permeability is exceptionally high across alveolar epithelia and endothelia and moderately high across airway epithelia. This review is focused on the role of membrane water-transporting proteins, the aquaporins (AQPs), in high lung water permeability and lung physiology. The lung expresses several AQPs: AQP1 in microvascular endothelia, AQP3 in large airways, AQP4 in large- and small-airway epithelia, and AQP5 in type I alveolar epithelial cells. Lung phenotype analysis of transgenic mice lacking each of these AQPs has been informative. Osmotically driven water permeability between the air space and capillary compartments is reduced approximately 10-fold by deletion of AQP1 or AQP5 and reduced even more by deletion of AQP1 and AQP4 or AQP1 and AQP5 together. AQP1 deletion greatly reduces osmotically driven water transport across alveolar capillaries but has only a minor effect on hydrostatic lung filtration, which primarily involves paracellular water movement. However, despite the major role of AQPs in lung osmotic water permeabilities, AQP deletion has little or no effect on physiologically important lung functions, such as alveolar fluid clearance in adult and neonatal lung, and edema accumulation after lung injury. Although AQPs play a major role in renal and central nervous system physiology, the data to date on AQP knockout mice do not support an important role of high lung water permeabilities or AQPs in lung physiology. However, there remain unresolved questions about possible non-water-transporting roles of AQPs and about the role of AQPs in airway physiology, pleural fluid dynamics, and edema after lung infection. 相似文献
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Alzheimer’s disease (AD) is characterized by an excessive accumulation of toxic amyloid beta (Aβ) plaques and memory dysfunction. The onset of AD is influenced by age, genetic background, and impaired glucose metabolism in the brain. Several studies have demonstrated that diabetes involving insulin resistance and glucose tolerance could lead to AD, ultimately resulting in cognitive dysfunction. Even though the relationship between diabetes and AD was indicated by significant evidences, the critical mechanisms and metabolic alterations in diabetes induced AD are not clear until now. Recently, iron metabolism has been shown to play multiple roles in the central nervous system (CNS). Iron deficiency and overload are associated with neurodegenerative diseases. Iron binds to Aβ and subsequently regulates Aβ toxicity in the CNS. In addition, previous studies have shown that iron is involved in the aggravation of insulin resistance. Considering these effects of iron metabolism in CNS, we expect that iron metabolism may play crucial roles in diabetic AD brain. Thus, we review the recent evidence regarding the relationship between diabetes-induced AD and iron metabolism. 相似文献
86.
几个生态因子对黄盖鲽的影响 总被引:1,自引:0,他引:1
黄盖鲽(Psuedopleuronectes yokohameGünther)是鲽科中的冷温性鱼类,广泛分布在日本、朝鲜及我国的东海、黄海和渤海。地方种群多,洄游范尉小,适应能力强,既是底栖生物食性,又可耐较低的温度,虽非名贵鱼种,却具有一定的经济价值,在开展近海增殖时,不存在越冬和效益外流问题。因此,早在60年代,日本山口县和大分县的学者们,便开始着手该品种的人工孵化和增殖放流试验。80年代初已达年放流2—3cm的稚鱼苗7.0×10~6尾的水平。为了在渤海开展增殖工作,建立综 相似文献
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冬眠周期长短不同的蒙古黄鼠(Citellus dauricus)... 总被引:1,自引:0,他引:1
Adult Mongolian ground squirrels (Citellus dauricus) were kept at 5 degrees C in winter and divided into four experimental groups according to the bout length. The first group was not hibernating until decapitation. The bout length of the second group was between 4-10 days, the third group 11-17 days and the fourth group longer than 20 days. All pineals were sampled at the end of January. Morphometric analytical procedures were used to study the ultrastructure of the distal part of the pineal gland. The statistical results demonstrated that 1) the euthermic animals have larger cross areas of pinealocyte, longer and narrower Golgi apparatus and more number of saccules of each Golgi apparatus (P less than 0.01). But they also have smaller volume density of vaculoes, less lipid droplets and associated vesicles around Golgi apparatus (P less than 0.01). 2) the hibernating animals with variety of bout length had no significant differences in the number of mitochondria, lipid droplets, lysosomes, the size of Golgi apparatus and the cross areas of nucleus and cytoplasm (P greater than 0.05). However, the number and the cross areas of vacuoles were significantly increased with the bout length (P less than 0.01). This might suggest that the bout length was not related to the metabolic activity of pinealocytes in Citellus dauricus and vacuoles might play some important roles in maintenance of individual bout of hibernation in this species. 相似文献
89.
PDCD4基因在过氧化氢诱导喉癌细胞凋亡中的作用 总被引:2,自引:0,他引:2
目的探讨过氧化氢诱导喉癌细胞Hep-2凋亡过程中PDCD4基因表达的变化。方法以体外培养的喉癌细胞Hep-2为实验材料,不同浓度的过氧化氢作用于Hep-2细胞,噻唑蓝(MTT)比色法测定细胞生存率,采用吖啶橙染色、Ho33342/PI荧光双染进行形态学观察,RT-PCR及Western blot检测PDCD4 mRNA水平及蛋白表达的变化,评价在过氧化氢诱导喉癌细胞Hep-2凋亡过程中PDCD4基因的作用。结果过氧化氢(200μmol/L)作用Hep-2细胞24h,能够显著抑制细胞增殖,并诱导细胞凋亡,同时引起pdcd4 mRNA水平显著上调,PDCD4蛋白表达显著增加。结论本研究首次报道PDCD4基因可能在氧化胁迫诱导喉癌细胞凋亡中起关键作用。 相似文献
90.
Mg2+ can potentially influence bacterial adhesion directly through effects on electrostatic interactions and indirectly by affecting physiology-dependent attachment processes. However, the effects of Mg2+ on biofilm structure are largely unknown. In this study, Pseudomonas fluorescens was used to investigate the influence of Mg2+ concentration (0, 0.1 and 1.0 mM MgCl2) on biofilm growth. Planktonic and attached cells were enumerated (based on DAPI staining) while biofilm structures were examined via confocal laser scanning microscopy and three-dimensional structures were reconstructed. Mg2+ concentration had no influence on growth of planktonic cells but, during biofilm formation, Mg2+ increased the abundance of attached cells. For attached cells, the influence of Mg2+ concentration changed over time, suggesting that the role of Mg2+ in bacterial attachment is complex and dynamic. Biofilm structures were heterogeneous and surface colonization and depth increased with increasing Mg2+ concentrations. Overall, for P. fluorescens, Mg2+ increased initial attachment and altered subsequent biofilm formation and structure. 相似文献