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Mikhail Linetsky Cibin T. Raghavan Kaid Johar Xingjun Fan Vincent M. Monnier Abhay R. Vasavada Ram H. Nagaraj 《The Journal of biological chemistry》2014,289(24):17111-17123
Advanced glycation end products (AGEs) contribute to lens protein pigmentation and cross-linking during aging and cataract formation. In vitro experiments have shown that ascorbate (ASC) oxidation products can form AGEs in proteins. However, the mechanisms of ASC oxidation and AGE formation in the human lens are poorly understood. Kynurenines are tryptophan oxidation products produced from the indoleamine 2,3-dioxygenase (IDO)-mediated kynurenine pathway and are present in the human lens. This study investigated the ability of UVA light-excited kynurenines to photooxidize ASC and to form AGEs in lens proteins. UVA light-excited kynurenines in both free and protein-bound forms rapidly oxidized ASC, and such oxidation occurred even in the absence of oxygen. High levels of GSH inhibited but did not completely block ASC oxidation. Upon UVA irradiation, pigmented proteins from human cataractous lenses also oxidized ASC. When exposed to UVA light (320–400 nm, 100 milliwatts/cm2, 45 min to 2 h), young human lenses (20–36 years), which contain high levels of free kynurenines, lost a significant portion of their ASC content and accumulated AGEs. A similar formation of AGEs was observed in UVA-irradiated lenses from human IDO/human sodium-dependent vitamin C transporter-2 mice, which contain high levels of kynurenines and ASC. Our data suggest that kynurenine-mediated ASC oxidation followed by AGE formation may be an important mechanism for lens aging and the development of senile cataracts in humans. 相似文献
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Jang DS Su BN Pawlus AD Kang YH Kardono LB Riswan S Afriastini JJ Fong HH Pezzuto JM Kinghorn AD 《Phytochemistry》2006,67(16):1832-1837
A C29-triterpene, beccaridiol (1), a dihydrochalcone natural product, 2',4'-dihydroxy-3-(4-methoxyphenyl)-propiophenone (2), as well as three known compounds, 4'-hydroxy-1',2'-dihydro-beta-ionone, 4'-O-methyldavidigenin (3), and ursolic acid, have been isolated from an EtOAc-soluble extract of the leaves of Diplectria beccariana. Beccaridiol (1) was characterized as an ursane-type 28-nortriterpene possessing an unusual aromatic E-ring by spectroscopic data interpretation. The relative configuration of this unusual isolate was established by analyzing the observed NOESY NMR correlations, and the absolute stereochemistry of 1 was then determined based on the circular dichroism (CD) spectrum of its 2,3-di-p-bromobenzoate (1b) derivative. All isolates were evaluated for their potential cancer chemopreventive properties utilizing a cell culture assay to determine quinone reductase induction. 相似文献
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Anshul I Arora Kaid Johar Devarshi U Gajjar Darshini A Ganatra Forum B Kayastha Anuradha K Pal Alpesh R Patel S Rajkumar Abhay R Vasavada 《Journal of biosciences》2012,37(1):979-987
Specimens of the anterior lens capsule with an attached monolayer of lens epithelial cells (LECs) were obtained from patients (n?=?52) undergoing cataract surgery. Specimens were divided into three groups based on the type of cataract: nuclear cataract, cortical cataract and posterior subcapsular cataract (PSC). Clear lenses (n?=?11) obtained from donor eyes were used as controls. Expression was studied by immunofluorescence, real-time PCR and Western blot. Statistical analysis was done using the student’s t-test. Immunofluorescence results showed punctate localization of Cx43 at the cell boundaries in controls, nuclear cataract and PSC groups. In the cortical cataract group, cytoplasmic pools of Cx43 without any localization at the cell boundaries were observed. Real-time PCR results showed significant up-regulation of Cx43 in nuclear and cortical cataract groups. Western blot results revealed significant increase in protein levels of Cx43 and significant decrease of ZO-1 in all three cataract groups. Protein levels of alpha-catenin were decreased significantly in nuclear and cortical cataract group. There was no significant change in expression of beta-catenin in the cataractous groups. Our findings suggest that ZO-1 and alpha-catenin are important for gap junctions containing Cx43 in the LECs. Alterations in cell junction proteins may play a role during formation of different types of cataract. 相似文献
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Mohamed Boussaid Cesar Benito Mériem Kaid Harche Tomás Naranjo Mohamed Zedek 《Biochemical genetics》2010,48(9-10):857-872
Intermicrosatellite PCR [inter-simple sequence repeat (ISSR)-PCR] markers and cytogenetics criteria were used to assess the level of genetic diversity and genetic structure in 17 populations of Stipa tenacissima (Gramineae) from Algeria. All populations sampled in the steppe area were diploids (2n = 2x = 24), and those sampled in the dry area were hexaploids (2n = 6x = 72). The dendrogram based on ISSR-PCR showed homogeneity within populations and large variability among populations. All individuals of the same population were gathered and formed groups clearly separated in all populations. These groups were separated into two clusters related to biotope, one from the steppe area and the other from the dry area. AMOVA indicated low genetic diversity among populations (30% of variation) and high within populations (70%). This variation pattern would constitute an adaptive strategy to grow in various ecological conditions. 相似文献
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Matthias Diebold Alex Soltermann Selma Hottinger Sarah R. Haile Lukas Bubendorf Paul Komminoth Wolfram Jochum Rainer Grobholz Dirk Theegarten Sabina Berezowska Kaid Darwiche Filiz Oezkan Malcolm Kohler Daniel P. Franzen 《Respiratory research》2017,18(1):210