Platelet-Activating Factor Quantification Using Reversed Phase Liquid Chromatography and Selected Reaction Monitoring in Negative Ion Mode

Platelet‐activating factor (PAF) is a potent biologically active phospholipid that mediates human physiological and pathophysiologic responses. PAF levels increase transiently and are typically assessed by techniques with limitations related to expense, sensitivity, pre‐analysis derivatization and interference with isobaric molecules. This study elucidates a facile, accurate liquid chromatography–mass spectrometry analytical method for PAF. In negative ion mode using electrospray ionization, collisionally‐activated dissociation analysis showed a unique product ion for acetate adducts of PAF molecular species representing the loss of methyl acetate from the polar head group and loss of a part of the acetate group from the sn‐2 position. This product ion was exploited for selected reaction monitoring of PAF molecular species following separation by reversed‐phase liquid chromatography. Standard calibration responses were determined, and this method was able to detect as low as 100 fmol of PAF. Finally, PAF molecular species were quantified in human neutrophils and monocytes.     

Dietary trans-Fatty Acid Induced NASH is Normalized Following Loss of trans-Fatty Acids from Hepatic Lipid Pools

Previous experiments in mice showed that dietary trans-fats could play a role in non-alcoholic steatohepatitis (NASH) yet little is known about the accumulation trans-fats in hepatic lipid pools in relationship to liver injury. NASH is also associated with obesity yet improves with only modest weight loss. To distinguish the role of obesity versus sustained consumption of a trans-fat containing diet in causing NASH, mice with obesity and NASH induced by consuming a high trans-fat diet for 16?weeks were subsequently fed standard chow or maintained on trans-fat chow for another 8?weeks. The accumulation, partitioning and loss of trans-fats in the major hepatic lipid pools during and after trans-fat consumption were determined. Obese mice switched to standard chow remained obese but steatohepatitis improved. trans-fats were differentially incorporated into the major hepatic lipid pools and the loss of trans-fats after crossover to control chow was greatest in the cholesteryl ester pool. In summary, dietary changes can improve the biochemical and histopathological changes of NASH despite persistent obesity in mice. Analysis of hepatic lipids confirmed that dietary trans-fats accumulate in the major lipid pools and are released differentially with diet normalization. The substantial loss of trans-fats from the cholesteryl ester pool in parallel with improvement in NASH suggests that this pool of trans-fats could play a role in the pathogenesis of NASH.     

2004年世界电子业--快乐日子又来了!

2003年:半导体业重返好时光 iSuppli公司预计,2003年世界半导体市场销售将增长13.9%,与2002年的增长1.6%不可同日而语.     

Evaluating the impact of energy interventions: home audits vs. community events

New Zealand’s housing stock tends to be of low thermal quality that can adversely affect the health and well-being of occupants as well as costing more than necessary to heat. Householders need information and motivation to make material changes and adopt new practices to achieve warmer and more energy-efficient homes. This study compares two different types of energy interventions with householders in three different suburbs in Dunedin, New Zealand. Two suburbs received a home energy audit whereby an auditor surveyed each house and provided personalised advice. Householders in the third suburb took part in community energy events that included general advice and practical workshops. The impacts of these interventions were evaluated through pre- and post-intervention surveys and post-intervention interviews. Home energy audits were successful in encouraging change both behavioural and practical, where it was possible. The energy events promoted community engagement and awareness relating to energy-saving actions. Participant feedback suggests that a combination of both types of intervention may be most effective in promoting household change, beginning with energy events in communities before offering home energy audits. This would enable people to share their thoughts and concerns about energy with the support of their social networks and engender trust in the process, before offering personalised audits. Overall, the results show that interventions need to be correctly targeted to appropriate communities to be effective.     

Chemotaxis in shear flow: Similarity solutions of the steady-state chemoattractant and bacterial distributions

When chemotactic bacteria are exposed to a concentration gradient of chemoattractant while flowing along a channel, the bacteria accumulate at the interface between the chemoattractant source and bacterial suspension. Assuming that the interface is no-slip, we can apply the shear flow approximation near the no-slip boundary and solve a steady-state convection-diffusion model for both chemoattractant and bacterial concentrations. We suggest similarity solutions for the two-dimensional problem and identify a critical length scale η_c for bacteria chemotaxis in a given concentration gradient. The analysis identifies three dimensionless groups representing, respectively, chemotactic sensitivity, the chemotaxis receptor constant, and the bacteria diffusion coefficient, which typically show coupled effects in experimental systems. We study the effect of the dimensionless groups separately and provide understanding of the system involving shear flow and chemotaxis.     

Examination of arsenic speciation in sulfidic solutions using X-ray absorption spectroscopy

Both thioarsenites and thioarsenates have been demonstrated to exist in sulfidic waters, yet there is uncertainty regarding the geochemical conditions that govern the formation of these arsenic species. The purpose of this research was to use advanced spectroscopy techniques, speciation modeling, and chromatography to elucidate the chemical speciation of arsenic in sulfidic solutions initially containing arsenite and sulfide. Results of X-ray absorption spectroscopy (XAS) show that experimental solutions contained mixtures of arsenite and thioarsenites with increasing substitution of sulfur for oxygen on arsenic as the sulfide concentration increased. Experimental samples showed no evidence of polymeric arsenic species, or transformation of thioarsenites to thioarsenates. The arsenic speciation measured using XAS was similar to predictions obtained from a thermodynamic model for arsenic speciation, excluding thioarsenate species in sulfidic systems. Our data cast some doubt on the application of chromatographic methods for determining thioarsenates and thioarsenites (or mixtures) in natural waters in cases where the arsenic oxidation state cannot be independently verified. The same chromatographic peak positions proposed for thioarsenates can be explained bythioarsenite species. Furthermore, sample dilution was shown to change the species distribution and care should be taken to avoid sample dilution prior to chromatographic analysis.     

Correction to Ford and Collins (2010).

Reports an error in "Self-esteem moderates neuroendocrine and psychological responses to interpersonal rejection" by Máire B. Ford and Nancy L. Collins (Journal of Personality and Social Psychology, 2010[Mar], Vol 98[3], 405-419). This article contained a misspelling in the last name of the first author in the below reference. The complete correct reference is included. The online version of the article has been corrected. (The following abstract of the original article appeared in record 2010-02829-005.) In this study, the authors investigated self-esteem as a moderator of psychological and physiological responses to interpersonal rejection and tested an integrative model detailing the mechanisms by which self-esteem may influence cognitive, affective, and physiological responses. Seventy-eight participants experienced an ambiguous interpersonal rejection (or no rejection) from an opposite sex partner in the context of an online dating interaction. Salivary cortisol was assessed at 5 times, and self-reported cognitive and affective responses were assessed. Compared with those with high self-esteem, individuals with low self-esteem responded to rejection by appraising themselves more negatively, making more self-blaming attributions, exhibiting greater cortisol reactivity, and derogating the rejector. Path analysis indicated that the link between low self-esteem and increased cortisol reactivity was mediated by self-blame attributions; cortisol reactivity, in turn, mediated the link between low self-esteem and increased partner derogation. Discussion centers on the role of self-esteem as part of a broader psychobiological system for regulating and responding to social threat and on implications for health outcomes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Dual band tunable EBG

An electromagnetic bandgap (EBG) surface that can be independently tuned over two separate frequency bands is demonstrated. The EBG consists of a dual layer of square element based designs with varactor diodes. The EBG tuning ranges for each band were from 600 to 1200 and 1700 to 2600 MHz.     

The role of physical health functioning, mental health, and sociodemographic factors in determining the intensity of mental health care use among primary care medical patients.

The present study examined sociodemographic and attitudinal predisposing factors (gender, age, marital status, health insurance, household income, attitudes about mental health care), and need/illness variables (depression severity, physical and mental health functional status) as predictors of past-year mental health care use intensity (i.e., visit counts) and use/nonuse. The sample included 283 adult primary care patients from the Midwestern United States in a cross-sectional study. Nonlinear regression models demonstrated that past-year treatment use intensity was significantly associated with both married status and poorer physical health functioning, while the use (vs. nonuse) of treatment was associated with depression severity. A sociodemographic and attitudinal multivariate predictor model only explained 5% of the variance in treatment use intensity, but a need/illness model significantly contributed an additional 23% variance. Poorer physical health functioning was significant in predicting treatment use intensity, while depression severity was significant in predicting the use (vs. nonuse) of treatment. Results demonstrate the particular importance of physical health problems in determining the intensity of mental health care use, and depression severity in determining the use/nonuse of treatment, notwithstanding the restricted sociodemographic contour of the sample. (PsycINFO Database Record (c) 2010 APA, all rights reserved)