) Maceil, C. E.; In The Encyclopedia of Nuclear Magnetic Resonance

Evanescent-wave cavity ring-down spectroscopy has been applied to a planar fused-silica surface covered with crystal violet (CV + ) cations to characterize the silanol groups indirectly. A radiation-polarization dependence of the adsorption isotherm of CV + at the CH 3 CN/silica interface is measured and fit to a two-site Langmuir equation to determine the relative populations of two different types of isolated silanol groups. CV + binding at type I sites yields a free energy of adsorption of -29.9 ( 0.2 kJ/mol and a saturation surface density of (7.4 ( 0.5) × 10 12 cm -2 , whereas the values of -17.9 ( 0.4 kJ/mol and (3.1 ( 0.4) × 10 13 cm -2 are obtained for the type II sites. The CV + cations, each with a planar area of ∼120 Å 2 , seem to be aligned randomly while lying over the SiOtype I sites, thereby suggesting that this type of site may be surrounded by a large empty surface area (>480 Å 2 ). In contrast, the CV + cations on a type II sites are restricted with an average angle of ∼40°tilted off the surface normal, suggesting that the CV + cations on these sites are grouped closely together. The average tilt angle increases with increasing concentration of crystal violet so that CV + cations may be separated from each other to minimize the repulsion of nearby CV + and SiOH sites. Adsorption behavior of organic molecules on silica surfaces has been the major theme of interface studies for improving the efficiency of chromatographic separations. When cationic molecules are involved, the strong electrostatic interaction with the negatively charged silanol (SiOH) groups on the surface of the stationary-phase silica may cause unwanted peak broadening and tailing, mainly from a slow kinetic response of the electrostatic adsorption. [1][2][3][4][5][6] The surface charge density is one of the primary factors influencing the strength of electrostatics. Accordingly, insight into how the cationic molecules interact with the local silanol groups of the silica surface should aid in the improvement of the design of surface modifications. Silanol groups play the main role in influencing the interfacial adsorption behavior, possessing an average surface density of ∼4.9 × 10 14 cm -2 on the silica surface 7-9 or an average surface area of 20.4 Å 2 per silanol group. As compared to silica sol particles, which have higher surface areas of (0.1-5) × 10 22 Å 2 /g, 7-9 only a few studies focus on characterization of silanol groups on a planar silica surface. 10-12 Ong et al. 10 first reported that isolated and vicinal silanol groups both exist at the water/silica interface possessing different pK a values of 4.9 and 8.5, with corresponding surface populations of 19 and 81%, respectively. These results were confirmed by means of cross-polarization magic angle spinning NMR 13 and fluorescence microscopy. 14 The isolated silanol groups with pK a ) 4.9 are anticipated to be separated far from each other (>5.5 Å), permitting proton dissociation. The vicinal silanol groups are located so closely as to form hydrogen bonds directly with their neighbors (<3.3 Å), which share 46% of the surface population, or through a water-molecule bridge (3.5-5.5 Å), which covers ∼35% of the surface population. 12,[15][16][17] By using second harmonic generation (SHG) with a cationic crystal violet (CV + ) molecular probe to investigate the local density distribution of the isolated silanols (pK a ) 4.9) on the planar fusedsilica surface, Xu and co-workers 12 classified them into two types. The first type of silanol group is anticipated to be surrounded by a large empty surface area (g120 Å 2 ) with a surface density o

Adipocyte dysfunction in a mouse model of polycystic ovary syndrome (PCOS): evidence of adipocyte hypertrophy and tissue-specific inflammation.

Clinical research shows an association between polycystic ovary syndrome (PCOS) and chronic inflammation, a pathological state thought to contribute to insulin resistance. The underlying pathways, however, have not been defined. The purpose of this study was to characterize the inflammatory state of a novel mouse model of PCOS. Female mice lacking leptin and insulin receptors in pro-opiomelanocortin neurons (IR/LepR(POMC) mice) and littermate controls were evaluated for estrous cyclicity, ovarian and adipose tissue morphology, and body composition by QMR and CT scan. Tissue-specific macrophage infiltration and cytokine mRNA expression were measured, as well as circulating cytokine levels. Finally, glucose regulation during pregnancy was evaluated as a measure of risk for diabetes development. Forty-five percent of IR/LepR(POMC) mice showed reduced or absent ovulation. IR/LepR(POMC) mice also had increased fat mass and adipocyte hypertrophy. These traits accompanied elevations in macrophage accumulation and inflammatory cytokine production in perigonadal adipose tissue, liver, and ovary. These mice also exhibited gestational hyperglycemia as predicted. This report is the first to show the presence of inflammation in IR/LepR(POMC) mice, which develop a PCOS-like phenotype. Thus, IR/LepR(POMC) mice may serve as a new mouse model to clarify the involvement of adipose and liver tissue in the pathogenesis and etiology of PCOS, allowing more targeted research on the development of PCOS and potential therapeutic interventions

IR/LepR^POMC females are hyperglycemic and show hyperglycemia during pregnancy.

<p>A. IR/LepR^POMC female glucose levels under basal conditions (n = 6–7) ** p<0.01. B. Fasted glucose levels in a second cohort of females, before pregnancy and on gestational day 12 and 15 (Black circles are control dams, open triangles are IR/LepR^POMC dams; n = 11–12) * p<0.05, compared with controls at same timepoint; ⁺ p<0.05, compared with pre-pregnancy values of same group. C. Glucose tolerance testing (2 g/kg) performed on day 15–18 of gestation. (Black circles are control dams, open triangles are IR/LepR^POMC dams; n = 6). Mean ± SEM.</p

IR/LepR^POMC females have reduced ovulation but show normal cycling suppression from fasting.

<p>A. Example of delay in resumption of estrous cycles measured by vaginal cytology taken before, during, and after a 48 hour fast. B. Delay from fast quantified for control (white bars) or IR/LepR^POMC (black bars) mice, n = 9–13 (not significant). Mean ± SEM.</p

Serum inflammatory markers are normal in IR/LepR^POMC Females.

<p>Cytokine levels were measured in serum by Bio-Plex cytokine array, n = 4–5. Mean ± SEM.</p><p>Tumor Necrosis Factor-alpha (TNF-α), Interferon-gamma (INF-γ),</p><p>monocyte chemotactic protein-1 (MCP-1).</p

IR/LepR^POMC Females have tissue-specific low-grade inflammation.

<p>A. Immunostaining for macrophage marker F4/80 in adipose tissue. F4/80 staining (FITC) was merged with DAPI to identify activated macrophages. B. Adipose tissue F4/80 gene expression. C. Adipose tissue CD11c gene expression. D. Adipose tissue IL-6 gene expression. E. Adipose tissue IL-1β gene expression. F. Ovary IL-6 gene expression. G. Liver IL-1β gene expression. Mean ± SEM, n = 4–5 *  =  p<.05 and **  =  p<.01 compared with controls.</p