Trapping Nitric Oxide by Surface Hydroxyls on Rutile TiO₂(110)

Hydroxyls are omnipresent on oxide surfaces under ambient conditions. While they unambiguously play an important role in many catalytic processes, it is not well-understood how these species influence surface chemistry at atomic scale. We investigated the adsorption of nitric oxide (NO) on a hydroxylated rutile TiO₂(110) surface with scanning tunneling microscopy (STM), X-ray/ultraviolet photoemission spectroscopy (XPS/UPS), and density functional theory (DFT) calculations. At room temperature adsorption of NO is only possible in the vicinity of a surface hydroxyl, and leads to a change of the local electronic structure. DFT calculations confirm that the surface hydroxyl-induced excess charge is transferred to the NO adsorbate, which results in an electrostatic stabilization of the adsorbate and, consequently, a significantly stronger bonding

Changes in Uric Acid Levels following Bariatric Surgery Are Not Associated with <em>SLC2A9</em> Variants in the Swedish Obese Subjects Study

<div><h3>Context and Objective</h3><p>Obesity and <em>SLC2A9</em> genotype are strong determinants of uric acid levels. However, data on <em>SLC2A9</em> variants and weight loss induced changes in uric acid levels are missing. We examined whether the changes in uric acid levels two- and ten-years after weight loss induced by bariatric surgery were associated with <em>SLC2A9</em> single nucleotide polymorphisms (SNPs) in the Swedish Obese Subjects study.</p> <h3>Methods</h3><p>SNPs (N = 14) identified by genome-wide association studies and exonic SNPs in the <em>SLC2A9</em> gene locus were genotyped. Cross-sectional associations were tested before (N = 1806), two (N = 1664) and ten years (N = 1201) after bariatric surgery. Changes in uric acid were compared between baseline and Year 2 (N = 1660) and years 2 and 10 (N = 1172). A multiple testing corrected threshold of P = 0.007 was used for statistical significance.</p> <h3>Results</h3><p>Overall, 11 of the 14 tested <em>SLC2A9</em> SNPs were significantly associated with cross-sectional uric acid levels at all three time points, with rs13113918 showing the strongest association at each time point (R² = 3.7−5.2%, 3.9×10⁻²²≤p≤7.7×10⁻¹¹). One SNP (rs737267) showed a significant association (R² = 0.60%, P = 0.002) with change in uric acid levels from baseline to Year 2, as common allele homozygotes (C/C, N = 957) showed a larger decrease in uric acid (−61.4 µmol/L) compared to minor allele carriers (A/X: −51.7 µmol/L, N = 702). No SNPs were associated with changes in uric acid from years 2 to 10.</p> <h3>Conclusions</h3><p>SNPs in the <em>SLC2A9</em> locus contribute significantly to uric acid levels in obese individuals, and the associations persist even after considerable weight loss due to bariatric surgery. However, we found little evidence for an interaction between genotype and weight change on the response of uric acid to bariatric surgery over ten years. Thus, the fluctuations in uric acid levels among the surgery group appear to be driven by the weight losses and gains, independent of <em>SLC2A9</em> genotypes.</p> </div

Diurnal urinary output after different types of bariatric surgery.

<p>Diurnal urinary output (U-Volume) in absolute values (upper panel) and in relation to body weight (lower panel) after gastric bypass surgery (GBP), after pure restrictive bariatric surgery (VBG/B) and in non-operated obese controls. Changes from baseline (Δ) at the 2 y and 10 y follow-up visits are displayed. Data are mean values adjusted for sex, age, baseline BMI and the baseline level of the respective variables. The bars represent the 95% confidence intervals. Differences between groups (upper panel) are given as mean (95% confidence intervals).*<i>P</i><0.01 and ***<i>P</i><0.001.</p

Cross-sectional associations between serum uric acid levels and <i>SLC2A9</i> SNPs in SOS bariatric surgery patients when number of subjects has been maximized locally.

<p>All models are adjusted for age, sex, and body weight. β values represent change in cross-sectional uric acid level (µmol/L) per copy of minor allele carried. To convert µmol/L to mg/dL divide values by 59.48.</p

Associations between changes in serum uric acid levels and <i>SLC2A9</i> SNPs in SOS bariatric surgery patients when number of subjects has been maximized locally.

<p>All models are adjusted for age, sex, and percent change in body weight. β values represent change in changes in uric acid level (µmol/L) per copy of minor allele carried. To convert µmol/L to mg/dL divide values by 59.48.</p

Basic characteristics of SOS subjects with DNA and data for uric acid levels in the total sample and by surgery group.

<p>Main effect P value is for the main effect of surgery technique on variable of interest. For variables showing a significant main effect of surgery technique, post-hoc pair-wise comparisons were run to test the mean difference between the combined banding group (vertical banded gastroplasty and banding) and gastric bypass group. N represents the number of subjects with DNA and data for uric acid level at each time point. To convert µmol/L to mg/dL divide values by 59.48.</p

Fungal colonization enriches nitrogen content of colonized surface litter (NS) relative to that of uncolonized golden-yellow litter (C) and litter remaining after grey surface is stripped by termites (S).

<p>C/N ratios (8a) and %C (8b) of colonized litter were significantly lower than that of uncolonized and stripped litter. %N of colonized litter was significantly higher than that of uncolonized and stripped litter (n = 5; error bars = 1 SE; p<0.001).</p

Termites (<i>Psammotermes allocerus</i>) consume fungal-colonized litter.

<p>Perennial <i>Stipagrostis ciliata</i> litter with termite casts intact (2a). Termite cast has been removed, showing termites (arrows) stripping the grey outer layer, leaving the golden-yellow interior (2b). Note the small remaining portion of grey litter in the upper center. Standing litter from 2a with cast removed showing that all grey outer surface has been stripped by termites inside the cast (2c). Examples of <i>S</i>. <i>sabulicola</i> stem litter used in the C/N analysis (2d): grey litter (upper right) was compared with golden-yellow stripped material (left and bottom) from inside termite casts and golden-yellow standing litter as seen in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0126977#pone.0126977.g001" target="_blank">Fig 1A</a>.</p

Weight reduction independent changes from baseline after GBP and VBG/B at the 10 year follow up (multiple linear regression analyses).

a<p><b>:</b> Unadjusted difference between year 10 and baseline within each group. Minus signs denote reductions. Means (±SD) ^bDifference between year 10 and baseline within each group after adjustment for change in body mass index (BMI), sex, age, baseline BMI and the baseline level of the respective variables. Minus signs denote reductions. Mean values.</p>b<p><b>:</b> Difference between year 10 and baseline after adjustment for change in body mass index (BMI), sex, age, baseline BMI and the baseline level of the respective variables. Minus signs denote reductions. Mean values.</p>c<p>: Difference between gastric bypass surgery (GBP) and pure restrictive bariatric surgery (VBG/B) after adjustment for BMI change, sex, age, baseline BMI and the baseline level of the respective variables. Minus signs denote larger reductions in GBP compared to VBG/B group. Figures between brackets denote 95% confidence interval.</p>#<p>Daily salt intake was calculated by multiplying urinary sodium values by 0.0585 (molecular weight of NaCl: 58.5).</p>*<p>P<0.05,</p>**<p>P<0.01 and ***P<0.001 for test of difference between the GBP group and the VBG/B group in adjusted changes, using multiple linear regression.</p

Surface moisture availability at Gobabeb Research and Training Centre, Namib Desert.

<p>High humidity (>95%), rainfall and fog precipitation over a seven-year continuous period (1982–1989) at GRTC. Data retrieved from the long-term data records of the GRTC First Order Meteorological Station, obtained on autographic drum recorders.</p><p>Surface moisture availability at Gobabeb Research and Training Centre, Namib Desert.</p