The interaction of lipid peroxides with cellular proteins has been postulated to contribute to cellular aging. A potential
target for such effects is tubulin, the building block of microtubules. We examined the concentration-dependent effects of
phosphatidylcholine hydroperoxides on the ability of tubulin to polymerize into microtubules. The results demonstrated that
even very low concentrations of peroxides were sufficient to interfere with the tubulin and, therefore, the microtubule function.
Decreased tubulin activity (as measured by tubulin GTPase activity) showed correlation with the modification of methionine
and cysteine in tubulin and a change in the tubulin conformational state as indicated by fluorescence and ultraviolet spectroscopic
measurements. As no effect on electric conductivity was observed, indicating that modulation of ionic binding was not involved,
the interaction mechanism may be a hydrophobic one. 相似文献
In this paper, the authors propose a method that incorporates mechanisms for handling ambiguity in speech and the ability of humans to create associations, and for formulating conversations based on rule base knowledge and common knowledge. Go beyond the level that can be achieved, using only conventional natural language processing and vast repositories of sample patterns. In this paper, the authors propose a method for computer conversation sentences generated using newspaper headlines as an example of how the common knowledge and associative ability are applied. 相似文献
The cover image, by Yuko Shimamura et al, is based on the Research Article Inhibitory effects of Japanese horseradish (Wasabia japonica) on the formation and genotoxicity of a potent carcinogen, acrylamide, DOI: 10.1002/jsfa.8055 .
Positron annihilation line-shape analysis is sufficiently sensitive to detect microstructural defects such as vacancies and dislocations. We are developing a portable positron annihilation system and applying this technique to fatigue damage in type 316 stainless steel and SA508 low alloy steel. The positron annihilation technique was found to be sensitive in the early fatigue life, i.e. up to 10% of the fatigue life, but showed little sensitivity in later stages of the fatigue life in type 316 stainless steel and SA508 low alloy steel. Type 316 stainless steel a higher positron annihilation sensitivity than that of SA508. It was considered that the amount of dislocation density change in the stainless steel was greater than that in the low alloy steel, because the initial microstructure contained a low dislocation density because of the solution heat treatment for the type 316 stainless steel. 相似文献
Cholesterol ozonation was carried out in ethanol-containing aqueous or nonaqueous solvent, and the ozonized products were
analyzed by chemiluminescence detection-HPLC with on-line electrospray MS (HPLC-CL-MS) and characterized on the basis of NMR
and FABMS. After the ozonolysis of cholesterol in water/ethanol (aqueous system) as well as in chloroform/ethanol (nonaqueous
system), a unique ethoxyhydroperoxide molecule (7α-ethoxy-3β-hydroxy-5α-B-homo-6-oxacholestane-5-hydroperoxide, termed “7α-ethoxy-5-OOH”)
appeared as main ozonation product. In addition to structural analysis, we confirmed the remarkable cytotoxicity of 7α-ethoxy-5-OOH
toward human lung adenocarcinoma A549 cells and found that its cytotoxicity is superior to that of the commonly known autoxidized
cholesterol (3β-hydroxycholest-5-ene-7-one). Hence, 7α-ethoxy-5-OOH is a toxic molecule of primary importance, arising during
cholesterol ozonation in the presence of ethanol. 相似文献
A modified method without using benzene for quantitative determination of total carbonyl compounds in heated and frying fats
and oils has been developed. The analysis is done by the reaction of 2,4-dinitrophenylhydrazine (2,4-DNP) with aldehydes and
ketones in 2-propanol. The optimal wavelength to determine the total carbonyl compounds is 420 nm where the 2,4-dinitrophenylhydrazone
(2,4-DNPH) derivatives from saturated and unsaturated aldehydes and ketones had the same molar absorption coefficient. The
modified method for the estimation of total carbonyl compounds in heated and frying oils using 2-propanol instead of benzene
as a solvent had a good correlation with the conventional method. 相似文献
Uromodulin, a urinary protein synthesized and secreted from the thick ascending limb (TAL) of the loop of Henle, is associated with hypertension through the activation of sodium reabsorption in the TAL. Uromodulin is a potential target for hypertension treatment via natriuresis. However, its biological function in epithelial cells of the distal nephron segment, particularly the collecting duct, remains unknown. Herein, we examined the regulation of uromodulin production during water deprivation in vivo as well as the effect of uromodulin on the activity of the water channel aquaporin−2 (AQP2) in vitro and in vivo using transgenic mice. Water deprivation upregulated uromodulin production; immunofluorescence experiments revealed uromodulin adhesion on the apical surface of the collecting duct. Furthermore, the activation of AQP2 was attenuated in mice lacking uromodulin. Uromodulin enhanced the phosphorylation and apical trafficking of AQP2 in mouse collecting duct cells treated with the vasopressin analog dDAVP. The uromodulin-induced apical trafficking of AQP2 was attenuated via endocytosis inhibitor treatment, suggesting that uromodulin activates AQP2 through the suppression of endocytosis. This study provides novel insights into the cross−talk between TAL and the collecting duct, and indicates that the modulation of uromodulin is a promising approach for diuresis and hypertension treatment. 相似文献