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During their biological life, proteins are exposed in a cumulative way to irreversible nonenzymatic posttranslational modifications that are responsible for their molecular aging and generate specific by-products called 'posttranslational modification derived products' (PTMDPs). PTMDPs are involved in the pathogenesis of various diseases such as diabetes mellitus, renal insufficiency and atherosclerosis, and are potential biomarkers in clinical practice. Nonenzymatic glycation refers to the spontaneous binding of glucose and reducing sugars to free amino groups and is amplified by oxidative processes (referred to as 'glycoxidation'). It generates many reactive by-products such as aldehydes and leads to the formation of 'advanced glycation end products' (AGEs). AGEs accumulate in vivo, alter tissue organization and activate membrane receptors such as RAGE, which triggers inflammatory responses. Carbamylation is due to the binding of isocyanic acid, formed in vivo either by spontaneous dissociation of urea or by action of myeloperoxidase on thiocyanate, and generates homocitrulline from lysine groups. Carbamylation leads to alteration of the structural and biological properties of proteins, and favors inflammation and atherosclerosis. PTMDPs may be assayed by different methods, among others LC-MS/MS or immunoassays, constitute a promising field of investigation in basic research and are potential major biomarkers in laboratory medicine.

Abstract Background Lower limb arterial calcification is a frequent, underestimated but serious complication of diabetes. The DIACART study is a prospective cohort study designed to evaluate the determinants of the progression of lower limb arterial calcification in 198 patients with type 2 diabetes. Methods Lower limb arterial calcification scores were determined by computed tomography at baseline and after a mean follow up of 31.20 ± 3.86 months. Serum RANKL (Receptor Activator of Nuclear factor kB Ligand) and bone remodeling, inflammatory and metabolic parameters were measured at baseline. The predictive effect of these markers on calcification progression was analyzed by a multivariate linear regression model. Results At baseline, mean ± SD and median lower limb arterial calcification scores were, 2364 ± 5613 and 527 respectively and at the end of the study, 3739 ± 6886 and 1355 respectively. Using multivariate analysis, the progression of lower limb arterial log calcification score was found to be associated with (β coefficient [slope], 95% CI, p-value) baseline log(calcification score) (1.02, 1.00–1.04, p

Abstract Background Accumulation of advanced glycation end-products (AGEs) is involved in age-related osteoarthritis (OA). Glyoxalase (Glo)-1 is the main enzyme involved in the removal of AGE precursors, especially carboxymethyl-lysine (CML). We aimed to investigate the expression of several AGEs and Glo-1 in human OA cartilage and to study chondrocytic Glo-1 regulation by inflammation, mediated by interleukin (IL)-1β. Methods Ex vivo, we quantified AGEs (pentosidine, CML, methylglyoxal-hydroimidazolone-1) in knee cartilage from 30 OA patients. Explants were also incubated with and without IL-1β, and we assessed Glo-1 protein expression and enzymatic activity. In vitro, primary cultured murine chondrocytes were stimulated with increasing concentrations of IL-1β to assess Glo-1 enzymatic activity and expression. To investigate the role of oxidative stress in the IL-1β effect, cells were also treated with inhibitors of mitochondrial oxidative stress or nitric oxide synthase. Results Ex vivo, only the human cartilage CML content was correlated with patient age (r = 0.78, p = 0.0031). No statistically significant correlation was found between Glo-1 protein expression and enzymatic activity in human cartilage and patient age. We observed that cartilage explant stimulation with IL-1β decreased Glo-1 protein expression and enzymatic activity. In vitro, we observed a dose-dependent decrease in Glo-1 mRNA, protein quantity, and enzymatic activity in response to IL-1β in murine chondrocytes. Inhibitors of oxidative stress blunted this downregulation. Conclusion Glo-1 is impaired by inflammation mediated by IL-1β in chondrocytes through oxidative stress pathways and may explain age-dependent accumulation of the AGE CML in OA cartilage.

Même si la vigne reste parmi les plantes cultivées une des plus économes en eau, se pose maintenant la question de la disponibilité et de l'accessibilité à la ressource en eau naturelle de qualité: eaux souterraines (infiltration, nappes), eaux de surface stagnantes (lacs, retenues de barrages) ou en écoulement (rivières, fleuves), eaux de mer, eaux usées traitées (REUT). Certaines de ces eaux peuvent contenir des composés d'intérêts nutritionnels pour les plantes, mais aussi être riches en sels dissous. L'objet de cette communication est d'étudier les technologies permettant d'affiner la teneur en sel de l'eau d'irrigation pour la vigne, quel que soit son origine et son niveau initial. Les techniques membranaires, osmose inverse, nanofiltration et électrodialyse sont ainsi comparées techniquement et évaluées économiquement. Les unes, nanofiltration et osmose inverse, à partir de membranes poreuses ou denses sous pression, consiste en une séparation de quasi tous les éléments dissous de l'eau (anions, cations, mais y compris les nutriments azotés, et minéraux) et ce quel que soit, pour l'osmose inverse, la salinité de l'eau initiale (e.g. eau de mer). L'autre l'électrodialyse, à partir de membranes denses ne filtre pas l'eau, mais extrait une quantité pilotable en ligne, de sels dissous (Na+ et Cl− en particulier sélectionnables) sous l'effet d'un champ électrique, afin de l'adapter aux sols ou plantes concernés

Apolipoprotein[a] phenotyping is a critically important method to explore the role of kringle-4 repeat number as a modulator of lipoprotein[a]-associated cardiovascular risk. The availability of a kringle-4 number-based reference standard is therefore necessary for a reliable and generally accepted classification of apo[a] phenotypes. We propose here a battery of recombinant apo[a] isoforms that may be used as the reference standard in various gel systems. Five plasmids encoding for r-apo[a] containing a known number (n = 9, 13, 17, 25, 33) of plasminogen-like kringle-4 copies were constructed, and transfected into the human embryonic kidney cell line 293. The electrophoretic mobility of the recombinant apo[a] isoforms expressed by these cells in a hollow-fiber bioreactor was determined after reduction by SDS-gel (agarose, acrylamide or a mixture of both) electrophoresis and immunoblotting using an antibody specific for human apo[a]. The equation of the linear relationship between log r-apo[a] kringle number and relative migration was used to determine the isoform size of apo[a] in normal human plasma. A very good correlation (r = 0.97) was found with the genotype (pulsed-field gel eletrophoresis of kpnI-digested restriction fragments of genomic DNA) and among electrophoretic methods. The proposed recombinant standard offers the possibility to identify apo[a] isoforms within a large range of molecular sizes, 9 to 33 kringle-4 copies, using simple electrophoretic techniques and a nomenclature based on its molecular structure, i.e., the number of kringle-4 repeats.—Anglés-Cano, E., S. Loyau, G. Cardoso-Saldaña, R. Couderc, and P. Gillery. A novel kringle-4 number-based recombinant apo[a] standard for human apo[a] phenotyping. J. Lipid Res. 1999. 40: 354–359.

The main propose of this study is to characterize the impact of chronological aging on mechanical, structural, biochemical, and morphological properties of type I collagen. We have developed an original approach combining a stress-strain measurement device with a portable Raman spectrometer to enable simultaneous measurement of Raman spectra during stress vs strain responses of young adult, adult and old rat tail tendon fascicles (RTTFs). Our data showed an increase in all mechanical properties such as Young's modulus, yield strength, and ultimate tensile strength with aging. At the molecular level, Raman data revealed that the most relevant frequency shift was observed at 938 cm−1 in Old RTTFs, which is assigned to the C–C. This suggested a long axis deformation of the peptide chains in Old RTTFs during tensile stress. In addition, the intensity of the band at 872 cm−1, corresponding to hydroxyproline decreased for young adult RTTFs and increased for the adult ones, while it remained unchanged for Old RTTFs during tensile stress. The amide III band (1242 and 1265 cm−1) as well as the band ratios I 1631 / I 1663 and I 1645 / I 1663 responses to tensile stress were depending on mechanical phases (toe, elastic and plastic). The quantification of advanced glycation end-products by LC-MS/MS and spectrofluorometry showed an increase in their content with aging. This suggested that the accumulation of such products was correlated to the alterations observed in the mechanical and molecular properties of RTTFs. Analysis of the morphological properties of RTTFs by SHG combined with CT-FIRE software revealed an increase in length and straightness of collagen fibers, whereas their width and wavy fraction decreased. Our integrated study model could be useful to provide additional translational information to monitor progression of diseases related to collagen remodeling in musculoskeletal disorders. Type I collagen is the major component of the extracellular matrix. Its architectural and structural organization plays an important role in the mechanical properties of many tissues at the physiological and pathological levels. The objective of this work is to develop an integrated approach to bring a new insight on the impact of chronological aging on the structural organization and mechanical properties of type I collagen. We combined a portable Raman spectrometer with a mechanical tensile testing device in order to monitor in real time the changes in the Raman fingerprint of type I collagen fibers during the mechanical stress. Raman spectroscopy allowed the identification of the type I collagen bonds that were affected by mechanical stress in a differential manner with aging. [Display omitted] [ABSTRACT FROM AUTHOR]

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