Elevated plasma free fatty acids increase cardiovascular risk by inducing plasma biomarkers of endothelial activation, myeloperoxidase and PAI-1 in healthy subjects

Background

Although there is a growing body of evidence showing that patients with type 2 diabetes mellitus (T2DM) have poor glycemic control in general, it is not clear whether T2DM patients with pre-existing cardiovascular diseases (CVD) are more or less likely to have good glycemic control than patients without pre-existing CVD. Our aim was to examine the degree of glycemic control among T2DM patients in Europe with and without pre-existing CVD.

Methods

This is a matched cohort study based on a multi-center, observational study with retrospective medical chart reviews of T2DM patients in Spain, France, United Kingdom, Norway, Finland, Germany, and Poland. Included patients were aged >= 30 years at time of diagnosis of T2DM, had added a SU or a PPARγ agonist to failing metformin monotherapy (index date) and had pre-existing CVD (cases). A control cohort with T2DM without pre-existing CVD was identified using 1:1 propensity score matching. With difference-in-difference approach, logistic and linear regression analyses were applied to identify differences in glycemic control by CVD during the follow up period, after controlling for baseline demographics, clinical information, and concurrent anti-hyperglycemic medication use.

Results

The percentage of case patients with adequate glycemic control relative to control patients during the 1st, 2nd, 3rd, and 4th years after the index date was 19.9 vs. 26.5, 16.8 vs. 26.5, 18.8 vs. 28.3, and 16.8 vs. 23.5 respectively. Cases were significantly less likely to have adequate glycemic control (odds ratio: 0.62; 95% confidence interval: 0.46-0.82) than controls after adjusting for baseline differences, secular trend, and other potential confounding covariates.

Conclusions

T2DM patients with pre-existing CVD tended to have poorer glycemic control than those without pre-existing CVD, all other factors being equal. It suggests that clinicians may need to pay more attention to glycemic control among T2DM patients with CVD.     

Optimizing a Proteomics Platform for Urine Biomarker Discovery

Biomarker discovery approaches in urine have been hindered by concerns for reproducibility and inadequate standardization of proteomics protocols. In this study, we describe an optimized quantitative proteomics strategy for urine biomarker discovery, which is applicable to fresh or long frozen samples. We used urine from healthy controls to standardize iTRAQ (isobaric tags for relative and absolute quantitation) for variation induced by protease inhibitors, starting protein and iTRAQ label quantities, protein extraction methods, and depletion of albumin and immunoglobulin G (IgG). We observed the following: (a) Absence of protease inhibitors did not affect the number or identity of the high confidence proteins. (b) Use of less than 20 μg of protein per sample led to a significant drop in the number of identified proteins. (c) Use of as little as a quarter unit of an iTRAQ label did not affect the number or identity of the identified proteins. (d) Protein extraction by methanol precipitation led to the highest protein yields and the most reproducible spectra. (e) Depletion of albumin and IgG did not increase the number of identified proteins or deepen the proteome coverage. Applying this optimized protocol to four pairs of long frozen urine samples from diabetic Pima Indians with or without nephropathy, we observed patterns suggesting segregation of cases and controls by iTRAQ spectra. We also identified several previously reported candidate biomarkers that showed trends toward differential expression, albeit not reaching statistical significance in this small sample set.With ongoing advances in mass spectrometry (MS) and proteomics technology, proteomics analysis is progressively occupying a central position in biomarker discovery platforms. Biofluids such as urine and blood are the preferred media for proteomics analysis because of their ease of collection and extensive history of use in clinical laboratory practice. Urine, in particular, is an information-rich fluid that can be collected non-invasively and in large quantities. Many urine proteins are produced or shed in the kidney and urogenital tract (1), making urine a promising proximal source of biomarkers for diseases affecting these structures.However, proteomics-based biomarker discovery in urine faces multiple challenges. Urine proteomics is complicated by low urine protein concentration, variations in pH, and high concentrations of salts and urea or other urine components that interfere with sample processing. The urine proteome can also change with individual variables such as hydration, diurnal change, diet, and physical activity as well as variation in sample collection, processing, and storage. In addition, urine proteomics shares the usual challenges of biomarker discovery in other biofluids such as throughput, cost, and the need for a reproducible and quantitative work flow.Isotopic or isobaric labeling methods to reduce variation, increase throughput, and enable quantitative analysis have been developed to address some of these challenges. One such method, isobaric tags for relative and absolute quantitation (iTRAQ)¹ (2), combines relative and absolute peptide quantification with multiplexing ability to enable an increased throughput as well as simultaneous comparison of up to eight samples within one experimental run. Variations induced by urine sample processing have been systematically evaluated for proteomics analyses using two-dimensional gel electrophoresis (3–6), differential gel electrophoresis (7), and liquid chromatography-coupled mass spectrometry (LC-MS) (5, 8, 9). However, no systematic analyses of urine sample collection and processing have been reported for iTRAQ.Before utilizing iTRAQ-based quantitative proteomics for urine biomarker discovery, we evaluated the impact of variation in several processing steps (addition of protease inhibitors, the starting protein quantities, quantity of the iTRAQ label, protein extraction methods, and depletion of abundant proteins) on iTRAQ protein identification and quantitation. Applying this optimized biomarker discovery protocol to small quantities of long frozen urine samples from the Pima longitudinal study of diabetic nephropathy, we observed patterns suggestive of segregation of cases and controls by iTRAQ spectra. We also observed trends toward differential expression in several proteins that had been identified as putative biomarkers in previous studies. However, given the small sample size, none of these proteins retained statistical significance after multiple testing correction.     

Suggestive Evidence for Darwinian Selection against Asparagine-Linked Glycans of Plasmodium falciparum and Toxoplasma gondii

We are interested in asparagine-linked glycans (N-glycans) of Plasmodium falciparum and Toxoplasma gondii, because their N-glycan structures have been controversial and because we hypothesize that there might be selection against N-glycans in nucleus-encoded proteins that must pass through the endoplasmic reticulum (ER) prior to threading into the apicoplast. In support of our hypothesis, we observed the following. First, in protists with apicoplasts, there is extensive secondary loss of Alg enzymes that make lipid-linked precursors to N-glycans. Theileria makes no N-glycans, and Plasmodium makes a severely truncated N-glycan precursor composed of one or two GlcNAc residues. Second, secreted proteins of Toxoplasma, which uses its own 10-sugar precursor (Glc₃Man₅GlcNAc₂) and the host 14-sugar precursor (Glc₃Man₉GlcNAc₂) to make N-glycans, have very few sites for N glycosylation, and there is additional selection against N-glycan sites in its apicoplast-targeted proteins. Third, while the GlcNAc-binding Griffonia simplicifolia lectin II labels ER, rhoptries, and surface of plasmodia, there is no apicoplast labeling. Similarly, the antiretroviral lectin cyanovirin-N, which binds to N-glycans of Toxoplasma, labels ER and rhoptries, but there is no apicoplast labeling. We conclude that possible selection against N-glycans in protists with apicoplasts occurs by eliminating N-glycans (Theileria), reducing their length (Plasmodium), or reducing the number of N-glycan sites (Toxoplasma). In addition, occupation of N-glycan sites is markedly reduced in apicoplast proteins versus some secretory proteins in both Plasmodium and Toxoplasma.Animals, fungi, and plants synthesize Asn-linked glycans (N-glycans) by means of a lipid-linked precursor containing 14 sugars (dolichol-PP-Glc₃Man₉GlcNAc₂) (26). Recently we used bioinformatics and experimental methods to show that numerous protists are missing sets of glycosyltransferases (Alg1 to Alg14) and so make truncated N-glycan precursors containing 0 to 11 sugars (46). For example, Entamoeba histolytica, which causes dysentery, makes N-glycan precursors that contain seven sugars (Man₅GlcNAc₂) (33). Giardia lamblia, a cause of diarrhea, makes N-glycan precursors that contain just GlcNAc₂ (41). N-glycan precursors may be identified by metabolic labeling with radiolabeled mannose (Entamoeba) or glucosamine (Giardia) (46). Unprocessed N-glycans of each protist may be recognized by wheat germ agglutinin 1 (WGA-1) (GlcNAc₂ of Giardia) or by the antiretroviral lectin cyanovirin-N (Man₅GlcNAc₂ of Entamoeba) (2, 33, 41).N-glycans are transferred from lipid-linked precursors to sequons (Asn-Xaa-Ser or Asn-Xaa-Thr, where Xaa cannot be Pro) on nascent peptides by an oligosaccharyltransferase (OST) (28). For the most part, transfer of N-glycans by the OST is during translocation, although there are human and Trypanosoma OSTs that transfer N-glycans after translocation (34, 45).N-glycan-dependent quality control (QC) systems for protein folding and endoplasmic reticulum (ER)-associated degradation (ERAD), which are present in most eukaryotes, are missing from Giardia and a few other protists that make truncated N-glycans (5, 26, 53). There is positive Darwinian selection for sequons (sites of N-glycans) that contain Thr in secreted and membrane proteins of organisms that have N-glycan-dependent QC (12). This selection occurs for the most part by an increased probability that Asn and Thr will be present in sequons rather than elsewhere in secreted and membrane proteins. In contrast, there is no selection on sequons that contain Ser, and there is no selection on sequons in the secreted proteins of organisms that lack N-glycan-dependent QC.For numerous reasons, we are interested in the N-glycans of Plasmodium falciparum and Toxoplasma gondii, which cause severe malaria and disseminated infections, respectively.(i) There has been controversy for a long time as to whether Plasmodium makes N-glycans. While some investigators identified a 14-sugar Plasmodium N-glycan resembling that of the human host (29), others identified no N-glycans (6, 22).(ii) There is also controversy concerning whether the N-glycans of Toxoplasma, after removal of Glc by glucosidases in the ER lumen, contain either 7 sugars (Man₅GlcNAc₂), like Entamoeba (32, 33), or 11 sugars (Man₉GlcNAc₂), like the human host (16, 19, 26). If it is Man₅GlcNAc₂, then Toxoplasma uses the dolichol-PP-linked glycan predicted by its set of Alg enzymes (32, 46). If it is Man₉GlcNAc₂, then Toxoplasma uses the dolichol-PP-linked glycan of the host cell (16, 19, 26).(iii) Both Plasmodium and Toxoplasma are missing proteins involved in N-glycan-dependent QC of protein folding (5).(iv) We hypothesize that there may be negative selection against N-glycans in Plasmodium and Toxoplasma, because the N-glycans added in the ER lumen during translocation will likely interfere with threading of nucleus-encoded apicoplast proteins into a nonphotosynthetic, chloroplast-derived organelle called the apicoplast (21, 35, 37, 48, 52, 54). Nucleus-encoded apicoplast proteins have a bipartite signal at the N terminus, which targets proteins first to the lumen of the ER and second to lumen of the apicoplast. This bipartite signal has been used in transformed plasmodia where green fluorescent protein (GFP) is targeted to the apicoplast with the bipartite signal of the acyl carrier protein (ACP_leader-GFP), to the secretory system with the signal sequence only (ACP_signal-GFP), and to the cytosol with the organelle-targeting transit peptide only (ACP_transit-GFP) (55). Similar constructs have been used to characterize signals that target nucleus-encoded proteins of Toxoplasma to the apicoplast (11, 25).Here we use a combination of bioinformatic, biochemical, and morphological methods to characterize the N-glycans of Plasmodium and Toxoplasma and to test our hypothesis that there is negative selection against N-glycans in protists with apicoplasts.     

Vacuum-ultraviolet photochemically initiated modification of polystyrene surfaces: morphological changes and mechanistic investigations.

Vacuum-ultraviolet (VUV) irradiation (lambda(exc): 172 +/- 12 nm) of polystyrene films in the presence of oxygen produced not only oxidatively functionalized surfaces, but generated also morphological changes. Whereas OH- and C[double bond, length as m-dash]O-functionalized surfaces might be used for e.g. secondary functionalization, enhanced aggregation or printing, processes leading to morphological changes open new possibilities of microstructurization. Series of experiments made under different experimental conditions brought evidence of two different reaction pathways: introduction of OH- and C[double bond, length as m-dash]O-groups at the polystyrene pathways is mainly due to the reaction of reactive oxygen species (hydroxyl radicals, atomic oxygen, ozone) produced in the gas phase between the VUV-radiation source and the substrate. However, oxidative fragmentation leading to morphological changes, oxidation products of low molecular weight and eventually to mineralization of the organic substrate is initiated by electronic excitation of the polymer leading to C-C-bond homolysis and to a complex oxidation manifold after trapping of the C-centred radicals by molecular oxygen. The pathways of oxidative functionalization or fragmentation could be differentiated by FTIR-ATR analysis of irradiated polystyrene surfaces before and after washing with acetonitrile and microscopic fluorescence analysis of the surfaces secondarily functionalized with the N,N,N-tridodecyl-triaza-triangulenium (TATA) cation. Ozonization of the polystyrene leads to oxidative functionalization of the polymer surface but cannot initiate the fragmentation of the polymer backbone. Oxidative fragmentation is initiated by electronic excitation of the polymer (contact-mode AFM analysis), and evidence of the generation of intermediate C-centred radicals is given e.g. by experiments in the absence of oxygen leading to cross-linking (solubility effects, optical microscopy, friction-mode AFM) and disproportionation (fluorescence).     

Construction of genetic linkage map of the medicinal and ornamental plant <Emphasis Type="Italic">Catharanthus roseus</Emphasis>

An integrated genetic linkage map of the medicinal and ornamental plant Catharanthus roseus, based on different types of molecular and morphological markers was constructed, using a F₂ population of 144 plants. The map defines 14 linkage groups (LGs) and consists of 131 marker loci, including 125 molecular DNA markers (76 RAPD, 3 RAPD combinations; 7 ISSR; 2 EST-SSR from Medicago truncatula and 37 other PCR based DNA markers), selected from a total of 472 primers or primer pairs, and six morphological markers (stem pigmentation, leaf lamina pigmentation and shape, leaf petiole and pod size, and petal colour). The total map length is 1131.9 cM (centiMorgans), giving an average map length and distance between two markers equal to 80.9 cM and 8.6 cM, respectively. The morphological markers/genes were found linked with nearest molecular or morphological markers at distances varying from 0.7 to 11.4 cM. Linkage was observed between the morphological markers concerned with lamina shape and petiole size of leaf on LG1 and leaf, stem and petiole pigmentation and pod size on LG8. This is the first genetic linkage map of C. roseus.     

Synthesis and evaluation of antifungal properties of a series of the novel 2-amino-5-oxo-4-phenyl-5,6,7,8-tetrahydroquinoline-3-carbonitrile and its analogues

A series of 2-amino-5-oxo-4-phenyl-5,6,7,8-tetrahydroquinoline-3-carbonitrile and various analogues have been synthesized in excellent isolated yields starting from various arylidenemalononitrile and 3-amino-2-cyclohexen-1-one in 1-propanol as solvent at reflux temperature in the absence of any added catalyst. All the synthesized compounds were evaluated for their antifungal activity. The relationship between functional group variation and biological activity of the evaluated compounds is discussed in the article.     

A halotolerant and thermotolerant <Emphasis Type="Italic">Bacillus</Emphasis> sp. degrades hydrocarbons and produces tensio-active emulsifying agent

A Bacillus sp. strain DHT, isolated from oil-contaminated soil, grew and produced biosurfactant when cultured in variety of substrate at salinities of up to 100 g l⁻¹ and temperatures up to 45°C. It was capable of utilizing crude oil, fuels, various pure alkanes and PAHs as a sole carbon and energy source across a wide range of temperature and salinity. Over the range evaluated, the degradation of hydrocarbon and biosurfactant production was not influenced by salinity (0–10% wv⁻¹) and temperature (30–45°C). The biosurfactant produced by the organism emulsified a range of hydrocarbons with hexadecane as the best substrate and toluene as the poorest. From 16S rDNA analysis, strain DHT was related to Bacillus licheniformis.     

Downregulation of high-isoelectric-point extracellular superoxide dismutase mediates alterations in the metabolism of reactive oxygen species and developmental disturbances in hybrid aspen

Transgenic hybrid aspen (Populus tremula L. x P. tremuloides Michx.) plants expressing a high-isoelectric-point superoxide dismutase (hipI-SOD) gene in antisense orientation were generated to investigate its function. Immunolocalization studies showed the enzyme to be localized extracellularly, in the secondary cell wall of xylem vessels and phloem fibers. The antisense lines of hipI-SOD exhibited a distinct phenotype; growth rate was reduced, stems were thinner and leaves smaller than in wild-type (WT) plants. The abundance of hipI-SOD was reduced in the bark and xylem of plants from these antisense lines. The vascular tissue of transgenic lines became lignified earlier than in WT plants and also showed an increased accumulation of reactive oxygen species (ROS). Xylem fibers and vessels were shorter and thinner in the transgenic lines than in WT plants. The total phenolic content was enhanced in the antisense lines. Furthermore, microarray analysis indicated that several enzymes involved in cell signaling, lignin biosynthesis and stress responses were upregulated in apical vascular tissues of transgenic plants. The upregulation of selected genes involved in lignin biosynthesis was also verified by real-time PCR. The results suggest that, in the transgenic plants, a premature transition into maturation occurs and the process is discussed in terms of the effects of increased accumulation of ROS due to reduced expression of hipI-SOD during development and differentiation.