Showing papers by "University of Saskatchewan published in 2008"

H2S as a Physiologic Vasorelaxant: Hypertension in Mice with Deletion of Cystathionine γ-Lyase

Abstract: Studies of nitric oxide over the past two decades have highlighted the fundamental importance of gaseous signaling molecules in biology and medicine The physiological role of other gases such as carbon monoxide and hydrogen sulfide (H2S) is now receiving increasing attention Here we show that H2S is physiologically generated by cystathionine γ-lyase (CSE) and that genetic deletion of this enzyme in mice markedly reduces H2S levels in the serum, heart, aorta, and other tissues Mutant mice lacking CSE display pronounced hypertension and diminished endothelium-dependent vasorelaxation CSE is physiologically activated by calcium-calmodulin, which is a mechanism for H2S formation in response to vascular activation These findings provide direct evidence that H2S is a physiologic vasodilator and regulator of blood pressure

Birth Weight and Risk of Type 2 Diabetes: A Systematic Review

Abstract: Context Low birth weight is implicated as a risk factor for type 2 diabetes. However, the strength, consistency, independence, and shape of the association have not been systematically examined. Objective To conduct a quantitative systematic review examining published evidence on the association of birth weight and type 2 diabetes in adults. Data Sources and Study Selection Relevant studies published by June 2008 were identified through literature searches using EMBASE (from 1980), MEDLINE (from 1950), and Web of Science (from 1980), with a combination of text words and Medical Subject Headings. Studies with either quantitative or qualitative estimates of the association between birth weight and type 2 diabetes were included. Data Extraction Estimates of association (odds ratio [OR] per kilogram of increase in birth weight) were obtained from authors or from published reports in models that allowed the effects of adjustment (for body mass index and socioeconomic status) and the effects of exclusion (for macrosomia and maternal diabetes) to be examined. Estimates were pooled using random-effects models, allowing for the possibility that true associations differed between populations. Data Synthesis Of 327 reports identified, 31 were found to be relevant. Data were obtained from 30 of these reports (31 populations; 6090 diabetes cases; 152 084 individuals). Inverse birth weight–type 2 diabetes associations were observed in 23 populations (9 of which were statistically significant) and positive associations were found in 8 (2 of which were statistically significant). Appreciable heterogeneity between populations (I 2 = 66%; 95% confidence interval [CI], 51%-77%) was largely explained by positive associations in 2 native North American populations with high prevalences of maternal diabetes and in 1 other population of young adults. In the remaining 28 populations, the pooled OR of type 2 diabetes, adjusted for age and sex, was 0.75 (95% CI, 0.70-0.81) per kilogram. The shape of the birth weight–type 2 diabetes association was strongly graded, particularly at birth weights of 3 kg or less. Adjustment for current body mass index slightly strengthened the association (OR, 0.76 [95% CI, 0.70-0.82] before adjustment and 0.70 [95% CI, 0.65-0.76] after adjustment). Adjustment for socioeconomic status did not materially affect the association (OR, 0.77 [95% CI, 0.70-0.84] before adjustment and 0.78 [95% CI, 0.72-0.84] after adjustment). There was no strong evidence of publication or small study bias. Conclusion In most populations studied, birth weight was inversely related to type 2 diabetes risk.

Subacute ruminal acidosis in dairy cows: the physiological causes, incidence and consequences.

Abstract: During subacute ruminal acidosis (SARA) rumen pH is depressed for several hours per day due to accumulation of volatile fatty acids and insufficient rumen buffering. Surveys suggested an incidence of SARA of between 19% and 26% in early and mid-lactation dairy cows. Causes of SARA include feeding excessive amounts of non-structural carbohydrates and highly fermentable forages, and insufficient dietary coarse fiber. Consequences of SARA include feed intake depression, reduced fiber digestion, milk fat depression, diarrhea, laminitis, liver abscesses, increased production of bacterial endotoxin and inflammation characterized by increases in acute phase proteins. The increase in endotoxin is similar among methods for SARA induction, but depends on the diet fed before induction. Increases in acute phase proteins vary among methods of SARA induction, even when the methods result in similar rumen pH depressions. This suggests that the inflammatory response might not be solely due to bacterial endotoxin in the rumen.

Solid acid catalyzed biodiesel production from waste cooking oil

Abstract: Various solid acid catalysts were evaluated for the production of biodiesel from low quality oil such as waste cooking oil (WCO) containing 15 wt.% free fatty acids. The zinc stearate immobilized on silica gel (ZS/Si) was the most effective catalyst in simultaneously catalyzing the transesterification of triglycerides and esterification of free fatty acid (FFA) present in WCO to methyl esters. The optimization of reaction parameters with the most active ZS/Si catalyst showed that at 200 °C, 1:18 oil to alcohol molar ratio and 3 wt.% catalysts loading, a maximum ester yield of 98 wt.% could be obtained. The catalysts were recycled and reused many times without any loss in activity.

Heuristic evaluation for games: usability principles for video game design

Abstract: Most video games require constant interaction, so game designers must pay careful attention to usability issues. However, there are few formal methods for evaluating the usability of game interfaces. In this paper, we introduce a new set of heuristics that can be used to carry out usability inspections of video games. The heuristics were developed to help identify usability problems in both early and functional game prototypes. We developed the heuristics by analyzing PC game reviews from a popular gaming website, and the review set covered 108 different games and included 18 from each of 6 major game genres. We analyzed the reviews and identified twelve common classes of usability problems seen in games. We developed ten usability heuristics based on the problem categories, and they describe how common game usability problems can be avoided. A preliminary evaluation of the heuristics suggests that they help identify game-specific usability problems that can easily be overlooked otherwise.

Positive polynomials and sums of squares

Abstract: Preliminaries Positive polynomials and sums of square Krivine's Positivstellensatz The moment problem Non-compact case Archimedean $T$-modules Schmudgen's Positivstellensatz Putinar's question Weak isotropy of quadratic forms Scheiderer's local-global principle Semidefinite programming and optimization Appendix 1: Tarski-Seidenberg theorem Appendix 2: Algebraic sets Bibiography

High-Precision Laser Spectroscopy D/H and 18O/16O Measurements of Microliter Natural Water Samples

Abstract: Newly available gas analyzers based on off-axis integrated cavity output spectroscopy (OA-ICOS) lasers have been advocated as an alternative to conventional isotope-ratio mass spectrometers (IRMS) for the stable isotopic analysis of water samples In the case of H2O, OA-ICOS is attractive because it has comparatively low capital and maintenance costs, the instrument is small and field laboratory portable, and provides simultaneous D/H and 16O/18O ratio measurements directly on H2O molecules with no conversion of H2O to H2, CO, or H2/CO2−water equilibration required Here we present a detailed assessment of the performance of a liquid-water isotope analyzer, including instrument precision, estimates of sample memory and sample mass effects, and instrumental drift We provide a recommended analysis procedure to achieve optimum results using OA-ICOS Our results show that, by using a systematic sample analysis and data normalization procedure routine, measurement accuracies of ± 08‰ for δD and ±01‰ δ18O ar

Measuring innovation culture in organizations

Abstract: Purpose – Academic and practitioner interest has focused on innovation as a method of competitive differentiation and as a way to create customer value. However, less attention has been devoted to developing a measure of innovation culture. The purpose of this paper is to develop an empirically‐based comprehensive instrument for measuring an organization's innovation culture.Design/methodology – This paper describes a procedure which explicates the innovation culture construct, and proposes a multi‐item measure of innovation culture predicated on exploratory factor analysis. These descriptors were derived from extant literature, key informant interviews, and a survey of over 282 employees from the financial services industry.Findings – Findings suggest that an innovation culture scale may best be represented through a structure that consists of seven factors identified as innovation propensity, organizational constituency, organizational learning, creativity and empowerment, market orientation, value orie...

Bullying: Are Researchers and Children/Youth Talking about the Same Thing?.

Abstract: Given the rapid increase in studies of bullying and peer harassment among youth, it becomes important to understand just what is being researched. This study explored whether the themes that emerge...

Guidelines for the management of chronic kidney disease

Abstract: New guidelines for the management of chronic kidney disease have been developed by the Canadian Society of Nephrology (Appendix 1 contains the full-text guidelines; available at [www.cmaj.ca/cgi/content/full/179/11/1154/DC1][1]). These guidelines describe key aspects of the management of chronic

Corticosterone in feathers is a long-term, integrated measure of avian stress physiology

Abstract: 1. Stress has pervasive consequences for the well-being of animals. Currently, understanding how individuals cope with stressors is typically accomplished via short-term quantification of blood glucocorticoids released after activation of the hypothalamic-pituitary-adrenal (HPA) axis. 2. We investigated whether the amount of corticosterone (CORT) deposited in growing feathers provides a long-term, integrated measure of HPA activity in birds using captive red-legged partridges Alectoris rufa as a model species. 3. We examined CORT levels in primary feathers induced to grow at the same time as stress series were performed with a capture and restraint protocol. Plasma CORT titres after stress-induced stimulation, but not baseline values, correlated with feather CORT. Feather levels showed the same pattern as plasma of decline across the breeding season, but more severely. 4. For females, CORT in naturally moulted flank feathers was highly and positively correlated with the number of eggs laid in the previous few months, but not clutch size of the following year. For males, the amount of black on a feather, known to be a social signal, was positively correlated with its CORT level. 5. The analysis of feather CORT is a novel methodology that allows for meaningful interpretations of how individuals respond to environmental perturbations and adjust to life-history stages. 6. The analysis of feather hormones has the unique advantages of allowing for experimentation and sampling at any time of the year with minimal investigator-induced impacts and artefacts, and shows the HPA activity of an individual with a flexible time frame from days to months depending on the length of time taken to grow the feather. As this technique can be applied to living or dead birds, or feathers picked up after moult, it provides the ultimate non-invasive physiological measure of considerable benefit in terms of animal welfare and sampling effort.

International variation in rates of uptake of preventive options in BRCA1 and BRCA2 mutation carriers.

Abstract: Several options for cancer prevention are available for women with a BRCA1 or BRCA2 mutation, including prophylactic surgery, chemoprevention and screening. The authors report on preventive practices in women with mutations from 9 countries and examine differences in uptake according to country. Women with a BRCA1 or BRCA2 mutation were contacted after receiving their genetic test result and were questioned regarding their preventive practices. Information was recorded on prophylactic mastectomy, prophylactic oophorectomy, use of tamoxifen and screening (MRI and mammography). Two thousand six hundred seventy-seven women with a BRCA1 or BRCA2 mutation from 9 countries were included. The follow-up questionnaire was completed a mean of 3.9 years (range 1.5-10.3 years) after genetic testing. One thousand five hundred thirty-one women (57.2%) had a bilateral prophylactic oophorectomy. Of the 1,383 women without breast cancer, 248 (18.0%) had had a prophylactic bilateral mastectomy. Among those who did not have a prophylactic mastectomy, only 76 women (5.5%) took tamoxifen and 40 women (2.9%) took raloxifene for breast cancer prevention. Approximately one-half of the women at risk for breast cancer had taken no preventive option, relying solely on screening. There were large differences in the uptake of the different preventive options by country of residence. Prophylactic oophorectomy is now generally accepted by women and their physicians as a cancer preventive measure. However, only the minority of women with a BRCA1 or BRCA2 mutation opt for prophylactic mastectomy or take tamoxifen for the prevention of hereditary breast cancer. Approximately one-half of women at risk for breast cancer rely on screening alone.

Probing Cold Dense Nuclear Matter

Abstract: The protons and neutrons in a nucleus can form strongly correlated nucleon pairs. Scattering experiments, in which a proton is knocked out of the nucleus with high-momentum transfer and high missing momentum, show that in carbon-12 the neutron-proton pairs are nearly 20 times as prevalent as proton-proton pairs and, by inference, neutron-neutron pairs. This difference between the types of pairs is due to the nature of the strong force and has implications for understanding cold dense nuclear systems such as neutron stars.

Sessile serrated adenoma (SSA) vs. traditional serrated adenoma (TSA)

Abstract: The morphologic distinction between various serrated polyps of the colorectum may be challenging. The distinction between sessile serrated adenoma (SSA) and traditional serrated adenoma (TSA) may be difficult using currently available criteria mostly based on cytologic characteristics. We have evaluated 66 serrated polyps including 29 SSA, 18 TSA, and 19 hyperplastic polyps for overall shape of the polyps, architectural features of individual crypts, the presence of eosinophilic cytoplasm, size and distribution of the proliferation and maturation zones, as well as Ki-67 and CK20 expression. The extent of the expression of CK20 and Ki-67 could not distinguish between the 3 types of serrated polyps, but the distribution of their expression was very helpful and differences were statistically significant. The distribution of Ki-67+ cells was the single most helpful distinguishing feature of the serrated polyp type (P<0.0001, chi test). Hyperplastic polyps had regular, symmetric, and increased Ki-67 expression. SSA had irregular, asymmetric, and highly variable expression of Ki-67. TSA had low Ki-67 expression, which was limited to "ectopic crypts" and admixed tubular adenomalike areas. In serrated polyps, ectopic crypt formation (ECF) defined by the presence of ectopic crypts with their bases not seated adjacent to the muscularis mucosae was nearly exclusive to TSA and was found in all cases, while the presence of cytologic atypia and eosinophilia of the cytoplasm were characteristic, but not limited to TSA. No evidence of ECF, but nevertheless abnormal distribution of proliferation zone was characteristic of SSA, whereas HP had neither. The presence of the ECF defines TSA in a more rigorous fashion than previous diagnostic criteria and also explains the biologic basis of exuberant protuberant growth associated with TSA and the lack of such growth in SSA. Recognition of this phenomenon may also help in exploring the genetic and molecular basis for differences between SSA and TSA, because these architectural abnormalities may well be a reflection of abnormalities in genetically programmed mucosal development.

Superconductivity in hydrogen dominant materials: Silane

Abstract: The metallization of hydrogen directly would require pressure in excess of 400 gigapascals (GPa), out of the reach of present experimental techniques. The dense group IVa hydrides attract considerable attention because hydrogen in these compounds is chemically precompressed and a metallic state is expected to be achievable at experimentally accessible pressures. We report the transformation of insulating molecular silane to a metal at 50 GPa, becoming superconducting at a transition temperature of Tc = 17 kelvin at 96 and 120 GPa. The metallic phase has a hexagonal close-packed structure with a high density of atomic hydrogen, creating a three-dimensional conducting network. These experimental findings support the idea of modeling metallic hydrogen with hydrogen-rich alloy.

Multistate Wind Energy Conversion System Models for Adequacy Assessment of Generating Systems Incorporating Wind Energy

Abstract: Wind energy is considered to be a very promising alternative for power generation because of its tremendous environmental, social, and economic benefits. Electrical power generation from wind energy behaves quite differently from that of conventional sources. The fundamentally different operating characteristics of those facilities, therefore, affect the power system reliability in a manner different from that of the conventional systems. This paper is focused on the development of suitable models for wind energy conversion systems, in adequacy assessments of generating systems, using wind energy. These analytical models can be used in the conventional generating system adequacy assessment utilizing analytical or Monte Carlo state-sampling techniques. This paper shows that a five-state wind energy conversion system model can be used to provide a reasonable assessment of the practical power system adequacy studies, using an analytical method, or a state-sampling simulation approach.

Exercise for Fibromyalgia: A Systematic Review

Abstract: Objective Fibromyalgia (FM) is a syndrome expressed by chronic widespread pain often associated with reduced physical function. Exercise is a common recommendation in management of FM. We evaluated the effects of exercise training on global well-being, selected signs and symptoms, and physical function in individuals with FM. Methods We searched Medline, Embase, CINAHL, SportDiscus, PubMed, PEDro, and the Cochrane Central Register for Controlled Trials to July 2005 and included randomized trials evaluating cardiorespiratory endurance, muscle strength, and flexibility. Methodological quality was assessed using the van Tulder and Jadad instruments. Training protocols were evaluated using American College of Sports Medicine (ACSM) guidelines. Clinical heterogeneity limited meta-analysis to 6 aerobic and 2 strength studies. Results There were 2276 subjects across the 34 studies; 1264 subjects were assigned to exercise interventions. Metaanalysis of 6 studies provided moderate-quality evidence that aerobic-only exercise training at ACSM-recommended intensity levels has positive effects on global well-being (SMD 0.49, 95% CI 0.23–0.75) and physical function (SMD 0.66, 95% CI 0.41–0.92) and possibly on pain (SMD 0.65, 95% CI –0.09 to 1.39) and tender points (SMD 0.23, 95% CI –0.18 to 0.65). Strength and flexibility remain underevaluated; however, strength training may have a positive effect on FM symptoms. Conclusion Aerobic-only training has beneficial effects on physical function and some FM symptoms. Strength-only training may improve FM symptoms, but requires further study. Large, high-quality studies of exercise-only interventions that provide detailed information on exercise prescription and adherence are needed.

Effects of metal content on activity and stability of Ni-Co bimetallic catalysts for CO2 reforming of CH4

Abstract: Ni-Co bimetallic catalyst with a general formula of Ni-Co-Al-Mg-O prepared using coprecipitation has shown excellent stability and high activity for CO2 reforming of CH4 in our previous research. This paper focuses on the effects of Ni-Co content of the catalyst, attempting to avoid carbon formation on the catalyst. Catalyst samples with Ni and Co loadings ranging between 1.83 and 14.5 wt.% and 2.76 and 12.9 wt.%, respectively, were prepared and the activity and stability for CO2 reforming of CH4 was tested at 750 °C and 1 atm using a high GHSV of 180,000 mL/gcat h. The results show that catalysts with lower Ni-Co content (1.83–3.61 wt.% for Ni and 2.76–4.53 wt.% for Co) had higher and more stable activity with no deactivation and no detectable carbon formation and that those of higher Ni-Co content (5.28–14.5 wt.% for Ni and 7.95–12.9 wt.% for Co) experienced apparent deactivation with significant carbon formation in 250 h time-on-stream tests. Catalyst characterizations using TEM, XRD, H2-TPR, TG/DTG-TPO, N2-physisorption, and CO-chemisorption indicate that catalyst with lower Ni-Co content has larger surface area, smaller metal particles and better metal dispersion and therefore gives rise to better catalytic performance. The absence of large metal particles (>10 nm) is believed essential to the complete suppression of the carbon formation during reaction.

Fischer–Tropsch synthesis: A review of water effects on the performances of unsupported and supported Co catalysts

Abstract: Fischer–Tropsch synthesis (FTS) process aims at converting synthesis gas to liquid fuels. Due to high activity and long catalyst life, cobalt-based catalyst is currently the catalyst of choice for gas to liquid (GTL) technology. Water is most undesirable byproduct of FTS process. Due to low water–gas-shift (WGS) activity of cobalt-based catalyst, the water concentration rises with time-on-stream (TOS) in FTS. This paper reviews the effects of water on the performances of various cobalt catalysts for FTS. The effects of water on FTS is quite complex and depends on the support and its nature, Co metal loading, its promotion with noble metals, and preparation procedure. Added water up to certain concentrations has positive effects (in terms of higher CO conversion, C 5+ selectivity, olefin selectivity and lower methane and CO 2 selectivity) on unsupported cobalt oxide catalysts. If the effects of support are taken into account, water has positive effect for silica-supported catalysts. The effects are negative for alumina where as for titania support, water has little positive effect. However in general, oxidation of cobalt active site depending on the cluster size and water partial pressure, the removal of transport restrictions via the formation of water-rich intra-pellet liquids, and kinetic effects have been considered as the main responsible factors. The effects are strongly influenced by the cobalt cluster size as well as on pore size of the support. Addition of noble metals at low cobalt loading increases the dispersion of cobalt on the support and hence improves its activity. Higher cobalt dispersion enhances the negative impact of water especially at higher water partial pressures under FTS conditions.

Physiological roles of plant glycoside hydrolases

Abstract: The functions of plant glycoside hydrolases and transglycosidases have been studied using different biochemical and molecular genetic approaches. These enzymes are involved in the metabolism of various carbohydrates containing compounds present in the plant tissues. The structural and functional diversity of the carbohydrates implies a vast spectrum of enzymes involved in their metabolism. Complete genome sequence of Arabidopsis and rice has allowed the classification of glycoside hydrolases in different families based on amino acid sequence data. The genomes of these plants contain 29 families of glycoside hydrolases. This review summarizes the current research on plant glycoside hydrolases concerning their principal functional roles, which were attributed to different families. The majority of these plant glycoside hydrolases are involved in cell wall polysaccharide metabolism. Other functions include their participation in the biosynthesis and remodulation of glycans, mobilization of energy, defence, symbiosis, signalling, secondary plant metabolism and metabolism of glycolipids.

Postnatal Inflammation Increases Seizure Susceptibility in Adult Rats

Abstract: There are critical postnatal periods during which even subtle interventions can have long-lasting effects on adult physiology. We asked whether an immune challenge during early postnatal development can alter neuronal excitability and seizure susceptibility in adults. Postnatal day 14 (P14) male Sprague Dawley rats were injected with the bacterial endotoxin lipopolysaccharide (LPS), and control animals received sterile saline. Three weeks later, extracellular recordings from hippocampal slices revealed enhanced field EPSP slopes after Schaffer collateral stimulation and increased epileptiform burst-firing activity in CA1 after 4-aminopyridine application. Six to 8 weeks after postnatal LPS injection, seizure susceptibility was assessed in response to lithium–pilocarpine, kainic acid, and pentylenetetrazol. Rats treated with LPS showed significantly greater adult seizure susceptibility to all convulsants, as well as increased cytokine release and enhanced neuronal degeneration within the hippocampus after limbic seizures. These persistent increases in seizure susceptibility occurred only when LPS was given during a critical postnatal period (P7 and P14) and not before (P1) or after (P20). This early effect of LPS on adult seizures was blocked by concurrent intracerebroventricular administration of a tumor necrosis factor α (TNFα) antibody and mimicked by intracerebroventricular injection of rat recombinant TNFα. Postnatal LPS injection did not result in permanent changes in microglial (Iba1) activity or hippocampal cytokine [IL-1β (interleukin-1β) and TNFα] levels, but caused a slight increase in astrocyte (GFAP) numbers. These novel results indicate that a single LPS injection during a critical postnatal period causes a long-lasting increase in seizure susceptibility that is strongly dependent on TNFα.