Morphologic Changes in Photoreceptor Outer Segments Following Photic Injury
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Morphologic changes characteristic of mild and severe cell injury produced in retinal photoreceptors by a xenon arc coagulator were studied by light and electron microscopy. Mild or reactive cell changes consisting of a tubulovesicular rearrangement or breakdown of cell membranes differed considerably from the production of myriad focal densifications of cell membranes and associated ground substances occurring in the severe injuries. The latter alterations are considered to beirreversible and, therefore, a characteristic of necrosis.Keywords:
Cell injury
Leading off from two places on the same cell (of Nitella) with 0.001 M KCl we observe that a cut produces only a temporary negative current of injury. If we lead off with 0.001 M KCl from any cell to a neighboring cell we find that when sap comes out from the cut cell and reaches the neighboring intact cell a lasting negative "current of injury" is produced. This depends on the fact that the intact cell is in contact with sap at one point and with 0.001 M KCl at the other (this applies also to tissues composed of small cells). If we employ 0.1 M KCl in place of 0.001 M the current of injury with a single cell is positive (and is more lasting when a neighboring cell is present). Divergent results obtained with tissues and single cells may be due in part to these factors.
Nitella
Cell injury
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Cell injury
Cell mediated immunity
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The normal cell maintains a steady state, termed homeostasis, in which the internal milieu of the cell is kept within physiological parameters. The response of a cell to any change in its environment constitutes the pathophysiological basis of clinical symptoms. When cells are faced with physiological or pathological stress they respond in several ways, collectively known as cellular adaptation. When the capacity of the cell to adapt is exceeded, then the cell undergoes a series of changes referred to as cell injury. The degree of injury dictates whether the cell will recover (i.e. reversible cell injury) or progress to cell death (i.e. irreversible cell injury). The effect on the tissue will depend on the duration of the injury, the nature of the injurious agent, the proportion and types of cells affected and the ability of the tissue to regenerate.
Cell injury
Cell type
Cell damage
Homeostasis
Pathophysiology
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Ion selective alumina membranes and silica-coated membranes are studied to generate electric power from a concentration gradient by reverse electrodialysis. The surface in alumina membranes is usually positively charged when contacting an electrolyte. In alumina membranes, pore interior has higher positive ions than negative ions. On the other hand, the surface in alumina membranes with silica coating is usually negatively charged when contacting an electrolyte. Consequently, alumina membranes are ionic selective for positive ions and silica-coated membranes are ionic selective for negative ions. It is much easier to manufacture the porous membranes than ion exchange membranes. When an electrolyte concentration gradient is applied between the membranes, electric power is generated. Experimental investigation is conducted for the power generation from these alumina membranes and silica-coated membranes placed between two sodium chloride solutions with constant concentration ratio. Ion selectivity of alumina membranes and silica-coated membranes is constant as concentrations of the solutions increase. Due to relatively easy and low cost fabrication processing of alumina membranes, power generation from concentration gradients with alumina membranes could be widely used in a various application area.
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LDL can injure endothelial cells in culture. HDL can inhibit this injurious effect of DDL. This effect of LDL seems to be independent of the LDL-receptor pathway since LDL-receptor negative cells were also injured. Ehdocytotic uptake of LDL appear not to be necessary for the DDL- induced cell injury to occur because LDL can injure both endothelial cells and erythrocytes at 4°C. By using radioactive 125I-DDL an increasing amount of 125I-LDL was shown to be associated with the cell with increasing concentrations of 125I-LDL in the incubation medium. A corresponding increase in cell injury as measured by 51Cr-release was observed. Presence of HDL in the incubation medium reduced both the cell associated radioactivity and the 51Cr-release. Thus, a relationship between the amount of 125I-DDL associated with the cell and the degree of cell injury was present. In conclusion, association of DDL to the cell surface seems to be closely related to the mechanism by which DDL can induce cell injury. Any kind of endocytotic uptake of DDL is not a prerequisite for the occurrence of DDL-mediated cell injury.
Cell injury
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Abstract Twelve kinds of cation‐exchange membranes were treated with hydrogen peroxide. Some of them (Selemion CMV, Nepton CR‐61, Scrion C‐100, SAM‐1) were completely destroyed. Heterogeneity is believed to be present in that part of their chemical structures that is decomposable by the treatment. The other membranes were converted into porous membranes by the decomposition of the resinous part. Water permeabilities and electric resistances of the porous membranes were examined to evaluate the pore radius. It was concluded that the “paste method” membranes have a heterogeneity or localized distribution of the resinous part under 50 mμ. The “paste method” membranes seemed to resemble the “graft method” membranes in chemical structure and to be much different from the mosaic‐type membranes such as Permaplex and MC‐3142. These results were also supported by extraction of the membranes with appropriate solvents and observation by electron microscopy.
Ion Exchange Membranes
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