Investigation of non-enzymatic glycosylation of human serum albumin using ion trap-time of flight mass spectrometry.

Non-enzymatic glycosylation or glycation involves covalent attachment of reducing sugar residues to proteins without enzyme participation. Glycation of glucose to human serum albumin in vivo is related to diabetes and many other diseases. We present an approach using liquid chromatography coupled to an electrospray ionization source of a hybrid ion trap-time of flight (IT-TOF-MS/MS) tandem mass spectrometer to identify the glycation sites on serum albumin from both a healthy person and a diabetic patient. The MetID software, which is commonly used for screening metabolites, is adapted for peptide fingerprinting based on both m/z values and isotopic distribution profiles. A total of 21 glycation sites from the healthy person and 16 glycation sites from the diabetic patient were identified successfully. We also demonstrate the use of matrix assisted laser desorption ionization-time of flight mass spectrometry to estimate the incorporation ratio of glucose to albumin during glycation. Results from this study show that the glycation in healthy person is more complicated than previously thought. Further analysis of incorporation ratio distribution may be necessary to accurately reflect the change of serum albumin glycation in diabetic patients.

Tyrosine nitrations impaired intracellular trafficking of FSHR to the cell surface and FSH-induced Akt-FoxO3a signaling in human granulosa cells.

Many infertile women suffered from poor ovarian response, and increased reactive oxygen species with age might mediate the poor ovarian response to FSH. In this study, we collected follicular fluids and isolated granulosa cells from female patients. Increased levels of peroxynitrite, tyrosine nitrations of FSH receptor (FSHR) and apoptosis were obviously detectable with decreased FSHR protein expressions in granulosa cells of the poor ovarian responders. In KGN (a human ovarian granulosa cell line) cells, exogenous peroxynitrite could sequester FSHR in the cytoplasm, and these dislocated FSHR might suffer from proteasome-mediated degradations. Here, we identified four peroxynitrite-mediated nitrated tyrosine residues of FSHR. Site-directed mutagenesis of FSHR revealed that Y626 was pivotal for intracellular trafficking of FSHR to the cell surface. Akt-induced inactivation of FoxO3a was required for the repression of FSH on granulosa cell apoptosis. However, peroxynitrite impaired FSH-induced Akt-FoxO3a signaling, while FSHR-Y626A mutant took similar effects. In addition, FoxO3a knockdown indeed impaired FSH-mediated cell survival, while FoxO3a-S253A mutant reversed that significantly.

Adsorption and co-adsorption of graphene oxide and Ni(II) on iron oxides: A spectroscopic and microscopic investigation.

Graphene oxide (GO) may strongly interact with toxic metal ions and mineral particles upon release into the soil environment. We evaluated the mutual effects between GO and Ni (Ni(II)) with regard to their adsorption and co-adsorption on two minerals (goethite and hematite) in aqueous phase. Results indicated that GO and Ni could mutually facilitate the adsorption of each other on both goethite and hematite over a wide pH range. Addition of Ni promoted GO co-adsorption mainly due to the increased positive charge of minerals and cation-π interactions, while the presence of GO enhanced Ni co-adsorption predominantly due to neutralization of positive charge and strong interaction with oxygen-containing functional groups on adsorbed GO. Increasing adsorption of GO and Ni on minerals as they coexist may thus reduce their mobility in soil. Extended X-ray absorption fine structure (EXAFS) spectroscopy data revealed that GO altered the microstructure of Ni on minerals, i.e., Ni formed edge-sharing surface species (at RNi-Fe∼3.2 Å) without GO, while a GO-bridging ternary surface complexes (at RNi-C∼2.49 Å and RNi-Fe∼4.23 Å) was formed with GO. These findings improved the understanding of potential fate and toxicity of GO as well as the partitioning processes of Ni ions in aquatic and soil environments.

Modulations of Keap1-Nrf2 signaling axis by TIIA ameliorated the oxidative stress-induced myocardial apoptosis.

Mounting evidence has strongly implicated oxidative stress in the development of cardiac dysfunction, and myocardial apoptosis contributes to the pathogenesis of heart failure. Quantitative cardiac proteomics data revealed that pressure load by TAC resulted in a significant decline in mitochondrial metabolic activity, where TIIA (Tanshinone IIA sulfonate) treatment reversed it in vivo, which might be mediated by Nrf2. In NRVMs, TIIA treatment ameliorated H2O2-induced caspase-3/9 activations through the suppression of p38 and mTOR signaling pathways, where caspase-mediated cleavage of YY1 and PARP resulted in the defects in mitochondrial biogenesis and DNA repair, and this event finally led to cardiomyocyte apoptosis. Mass spectrometry analysis showed that TIIA hydrophobically interacted with Keap1 (the cytoplasmic repressor of Nrf2) and induced its degradation in vitro. Site-directed mutagenesis of Keap1 identified V122/V123/I125 to be the critical residues for the TIIA-induced de-dimerization and degradation of Keap1. Besides, TIIA treatment also epigenetically up-regulated Nrf2 gene transcription, where it hypomethylated the first 5 CpGs of Nrf2 promoter. Furthermore, cardiac-specific Nrf2 knockout mice exhibited the significantly dampened anti-apoptotic effects of TIIA.

The enhancement roles of layered double hydroxide on the reductive immobilization of selenate by nanoscale zero valent iron: Macroscopic and microscopic approaches.

Herein, we utilized nanoscale zero-valent iron loaded on layered double hydroxide (NZVI/LDH) to immobilize Se(VI) and evaluated the enhancement role of LDH in the NZVI reaction system. The structural characterization indicated that LDH could stabilize and disperse NZVI as well as prevent NZVI from oxidation, thereby increasing iron reactivity. Batch experiments displayed that, compared with those by NZVI, both extent and rate of Se(VI) immobilized by NZVI/LDH significantly increased, owing to the prominent synergistic effect ascribing from adsorption and reduction. Kinetics studies under a series of conditions showed that Se(VI) reaction could be well described by pseudo first-order model. The performance of Se(VI) immobilization was inhibited to a considerable extent by most of co-existing ions, Nevertheless, the presence of Cu2+ improved performance of NZVI/LDH due to its role as a catalyst or medium of charge transfer during reduction. XANES revealed that LDH acted as a promoter for complete reduction of Se(VI) into Se(0)/Se(-II) over a wide pH range, whereas EXAFS suggested that LDH acted as a scavenger for insoluble products, making more reactive sites exposure to Se(VI) for reduction. These results suggested that NZVI/LDH as a promising candidate exhibited potential application in remediation of wastewaters containing Se(VI).

Macroscopic and spectroscopic studies of the enhanced scavenging of Cr(VI) and Se(VI) from water by titanate nanotube anchored nanoscale zero-valent iron.

Herein, a promising titanate nanotubes (TNT) anchored nanoscale zero-valent iron (NZVI) nanocomposite (NZVI/TNT) was synthesized, characterized and used for the enhanced scavenging of Cr(VI) and Se(VI) from water. The structural identification indicated that NZVI was uniformly loaded on TNT, thereby, the oxidation and aggregation of NZVI was significantly minimized. The macroscopic experimental results indicated that NZVI/TNT exhibited higher efficiency as well as rate on Cr(VI) and Se(VI) scavenging resulted from the good synergistic effect between adsorption and reduction. Besides, TNT can weaken the inhibitory effect of co-existing humic acid (HA) and fulvic acid (FA) on the scavenging of Cr(VI) and Se(VI) by NZVI, since TNT showed strong adsorption for HA and FA that inhibit potential reactivity. XPS analysis suggested that surface-bound Fe(II) played a critical role in Cr(VI) and Se(VI) scavenging. XANES analysis demonstrated that TNT acted as a promoter for the almost complete transformation of Cr(VI) into Cr(III), and Se(VI) into Se(0)/Se(-II) in NZVI system. EXAFS analysis indicated that TNT acted as a scavenger for insoluble products, and thus more reactive sites can be used for Cr(VI) and Se(VI) reduction. The excellent performance of NZVI/TNT provide a potential material for purification and detoxification of Cr(VI) and Se(VI) from wastewater.

Application of on-line nanoLC-IT-TOF in the identification of serum ß-catenin complex in mice scald model.

Severe burn shock remains an unresolved clinical problem with an urgent need to explore novel therapeutic treatments. Intracellular ß-catenin, through interaction with other proteins, has been reported to be able to regulate the size of cutaneous wounds. Higher expression of ß-catenin is associated with larger sized wounds. However, the identification of serum ß-catenin complex is difficult and has been rarely reported. The exploitation of more binding partners can contribute to uncovering the exact mechanisms behind serum ß-catenin mediated biological effects. Here, we describe a method that consists of immunoprecipitation, SDS-PAGE, in-gel digestion, and nanoLC coupled to LCMS-IT-TOF for the investigation of serum ß-catenin complex in mice scald model. Among selected gel bands obtained from the protein gels, a total of 31 peptides were identified and sequenced with high statistical significance (p<0.01). Three proteins (alpha-2-marcoglobulin, serine protease inhibitor A3K, and serine protease inhibitor A1A) were identified and validated with high reliability and high reproducibility. It was inferred that these proteins might interact with serum ß-catenin, which could affect the wound healing resulting from burn shock. Our study demonstrated that the on-line coupling of nano-LC with a LCMS-IT-TOF mass spectrometer was capable of sensitive and automated characterization of the serum ß-catenin complex in mice scald model.

[Analysis of the difference in the tissue surfaces between the old and new upper complete dentures].

OBJECTIVE: To investigate the reduction in residual ridges of maxillary edentulous models duplicated from old and new complete dentures using the 3-D data analysis. METHODS: Twenty-six pairs of maxillary edentulous models copied from the fitting surfaces of new and old upper complete dentures were selected for this study. The 3-D data were collected with a laser scanning system. The data were matched using Geomagic Studio 8 and Rapidform2006 software and then the fitting surfaces of new complete dentures were analyzed in comparison with old ones. RESULTS: The total amount of morphologic change of fitting surface [(39.8+/-14.2)%] was greater than the change of width [(28.2+/-16.0)%]; the area reduction of the residual ridge in anterior region [(43.0+/-15.2)%] was larger than that in posterior region [(36.1+/-14.1)%]; and the area reduction of residual ridge in buccal aspect [(42.9+/-13.8)%] was larger than that in lingual aspect [(35.5+/-15.2)%]. All the differences were statistically significant (P<0.05). CONCLUSIONS: The results of this study reveal that 3-D analysis of the whole change of the residual ridge is significant and verify that the residual ridge resorption of edentulous maxilla in three dimensions is greater in buccal aspect than in lingual aspect and greater in anterior region than in posterior region.