Simultaneous determination of wave speed and arrival time of reflected waves using the pressure-velocity loop

This is the post print version of the article. The official published version can be found at the link below.In a previous paper we demonstrated that the linear portion of the pressure–velocity loop (PU-loop) corresponding to early systole could be used to calculate the local wave speed. In this paper we extend this work to show that determination of the time at which the PU-loop first deviates from linearity provides a convenient way to determine the arrival time of reflected waves (Tr). We also present a new technique using the PU-loop that allows for the determination of wave speed and Tr simultaneously. We measured pressure and flow in elastic tubes of different diameters, where a strong reflection site existed at known distances away form the measurement site. We also measured pressure and flow in the ascending aorta of 11 anaesthetised dogs where a strong reflection site was produced through total arterial occlusion at four different sites. Wave speed was determined from the initial slope of the PU-loop and Tr was determined using a new algorithm that detects the sampling point at which the initial linear part of the PU-loop deviates from linearity. The results of the new technique for detecting Tr were comparable to those determined using the foot-to-foot and wave intensity analysis methods. In elastic tubes Tr detected using the new algorithm was almost identical to that detected using wave intensity analysis and foot-to-foot methods with a maximum difference of 2%. Tr detected using the PU-loop in vivo highly correlated with that detected using wave intensity analysis (r 2 = 0.83, P < 0.001). We conclude that the new technique described in this paper offers a convenient and objective method for detecting Tr, and allows for the dynamic determination of wave speed and Tr, simultaneously

Can air pollution affect tear film stability? a cross-sectional study in the aftermath of an explosion accident

<p>Abstract</p> <p>Background</p> <p>After an explosion and fire in two tanks containing contaminated oil and sulphur products in a Norwegian industrial harbour in 2007, the surrounding area was polluted. This caused an intense smell, lasting until the waste was removed two years later. The present study reports examinations of tear film break up time among the population. The examinations were carried out because many of the people in the area complained of sore eyes. The purpose of the study was to assess the relationship between living or working close to the polluted area and tear film stability one and a half years after the explosion.</p> <p>Methods</p> <p>All persons working or living in an area less than six kilometres from the explosion site were invited to take part in the study together with a similar number of persons matched for age and gender living more than 20 kilometres away. Three groups were established: workers in the explosion area and inhabitants near the explosion area (but not working there) were considered to have been exposed, and inhabitants far away (who did not work in the explosion area) were considered to be unexposed. A total of 734 people were examined, and the response rate was 76 percent. Tear film stability was studied by assessing non-invasive break-up time (NIBUT) using ocular microscopy. In addition Self-reported Break Up Time (SBUT) was assessed by recording the time the subject could keep his or hers eyes open without blinking when watching a fixed point on a wall. Background information was obtained using a questionnaire. Non-parametric Wilcoxon-Mann-Whitney-tests with exact p-values and multiple logistic regression analyses were performed.</p> <p>Results</p> <p>Both NIBUT and SBUT were shorter among the male exposed workers than among the inhabitants both near and far away from the explosion area. This was also found for SBUT among males in a multiple logistic regression analysis, adjusting for age and smoking.</p> <p>Conclusions</p> <p>Reduced tear film stability was found among workers in an area where an explosion accident had occurred.</p

Negative Effects of Paternal Age on Children's Neurocognitive Outcomes Can Be Explained by Maternal Education and Number of Siblings

Background: Recent findings suggest advanced paternal age may be associated with impaired child outcomes, in particular, neurocognitive skills. Such patterns are worrisome given relatively universal trends in advanced countries toward delayed nuptiality and fertility. But nature and nurture are both important for child outcomes, and it is important to control for both when drawing inferences about either pathway. Methods and Findings: We examined cross-sectional patterns in six developmental outcome measures among children in the U.S. Collaborative Perinatal Project (n = 31,346). Many of these outcomes at 8 mo, 4 y, and 7 y of age (Bayley scales, Stanford Binet Intelligence Scale, Graham-Ernhart Block Sort Test, Wechsler Intelligence Scale for Children, Wide Range Achievement Test) are negatively correlated with paternal age when important family characteristics such as maternal education and number of siblings are not included as covariates. But controlling for family characteristics in general and mother’s education in particular renders the effect of paternal age statistically insignificant for most developmental measures. Conclusions: Assortative mating produces interesting relationships between maternal and paternal characteristics that can inject spurious correlation into observational studies via omitted variable bias. Controlling for both nature and nurture reveals little residual evidence of a link between child neurocognitive outcomes and paternal age in these data. Result

Influence of the central-to-peripheral arterial stiffness gradient on the timing and amplitude of wave reflections

In individuals with compliant aortas, peripheral muscular artery stiffness exceeds central elastic artery stiffness. With ageing, central stiffness increases, with little change in peripheral stiffness, resulting in a reversal of the normal stiffness gradient. This reversal may reduce wave reflection amplitude, due to movement of the major “effective” reflection site further from the heart. To test this, we investigated the relationship among arterial stiffness gradients (normal and reversed), wave reflection amplitude and reflection site distance. Subjects aged ≥50years were recruited from the Anglo-Cardiff Collaborative Trial. Central stiffness was assessed by carotid-femoral pulse wave velocity (cfPWV). In study 1, peripheral PWV was also measured in the arm (carotid-radial, crPWV), and in study 2 in the leg (femoral- dorsalis pedis, fpPWV). Reflection site distance was calculated from cfPWV and reflected wave travel time. Subjects were dichotomized into those with a normal stiffness gradient (peripheral>central PWV), or a reversed gradient (peripheral<central PWV). In study 1, reflection site distance was greater in subjects with a reversed gradient (P<0.01), whereas time to reflection was lower (P<0.001). Both augmentation pressure (P<0.001) and augmentation index (P<0.05) were greater in subjects with a reversed gradient. In study 2, augmentation pressure, augmentation index and reflection site distance were greater in subjects with a reversed stiffness gradient (P<0.01, P<0.05 and P<0.01, respectively), and time to reflection was not different between groups. A reversed arterial stiffness gradient is associated with increased reflection site distance and a paradoxical increase in reflected wave amplitude, and augmentation index

Perceived crime and traffic safety is related to physical activity among adults in Nigeria

Background: Neighborhood safety is inconsistently related to physical activity, but is seldom studied in developing countries. This study examined associations between perceived neighborhood safety and physical activity among Nigerian adults. Methods: In a cross-sectional study, accelerometer-based physical activity (MVPA), reported walking, perceived crime and traffic safety were measured in 219 Nigerian adults. Logistic regression analysis was conducted, and the odds ratio for meeting health guidelines for MVPA and walking was calculated in relation to four safety variables, after adjustment for potential confounders. Results: Sufficient MVPA was related to more perception of safety from traffic to walk (OR = 2.28, CI = 1.13-6.25) and more safety from crime at night (OR = 1.68, CI = 1.07-3.64), but with less perception of safety from crime during the day to walk (OR = 0.34, CI = 0.06- 0.91). More crime safety during the day and night were associated with more walking. Conclusions: Perceived safety from crime and traffic were associated with physical activity among Nigerian adults. These findings provide preliminary evidence on the need to provide safe traffic and crime environments that will make it easier and more likely for African adults to be physically active

Differential gene expression in male and female rainbow trout embryos prior to the onset of gross morphological differentiation of the gonads

<p>Abstract</p> <p>Background</p> <p>There are large differences between the sexes at the genetic level; these differences include heterogametic sex chromosomes and/or differences in expression of genes between the sexes. In rainbow trout (<it>Oncorhynchus mykiss</it>) qRT-PCR studies have found significant differences in expression of several candidate sex determining genes. However, these genes represent a very small fraction of the genome and research in other species suggests there are large portions of the transcriptome that are differentially expressed between the sexes. These differences are especially noticeable once gonad differentiation and maturation has occurred, but less is known at earlier stages of development. Here we use data from a microarray and qRT-PCR to identify genes differentially expressed between the sexes at three time points in pre-hatch embryos, prior to the known timing of sexual differentiation in this species.</p> <p>Results</p> <p>The microarray study revealed 883 differentially expressed features between the sexes with roughly equal numbers of male and female upregulated features across time points. Most of the differentially expressed genes on the microarray were not related to sex function, suggesting large scale differences in gene expression between the sexes are present early in development. Candidate gene analysis revealed <it>sox9</it>, <it>DMRT1</it>, <it>Nr5a1 </it>and <it>wt1 </it>were upregulated in males at some time points and <it>foxl2</it>, <it>ovol1</it>, <it>fst </it>and <it>cyp19a1a </it>were upregulated in females at some time points.</p> <p>Conclusion</p> <p>This is the first study to identify sexual dimorphism in expression of the genome during embryogenesis in any fish and demonstrates that transcriptional differences are present before the completion of gonadogenesis.</p

Structural Analysis of the Essential Resuscitation Promoting Factor YeaZ Suggests a Mechanism of Nucleotide Regulation through Dimer Reorganization

Extent: 8p.Background: The yeaZ gene product forms part of the conserved network YjeE/YeaZ/YgjD essential for the survival of many Gram-negative eubacteria. Among other as yet unidentified roles, YeaZ functions as a resuscitation promoting factor required for survival and resuscitation of cells in a viable but non-culturable (VBNC) state. Methodology/Principal Findings: In order to investigate in detail the structure/function relationship of this family of proteins we have performed X-ray crystallographic studies of Vibrio parahaemolyticus YeaZ. The YeaZ structure showed that it has a classic actin-like nucleotide-binding fold. Comparisons of this crystal structure to that of available homologues from E. coli, T. maritima and S. typhimurium revealed two distinctly different modes of dimer formation. In one form, prevalent in the absence of nucleotide, the putative nucleotide-binding site is incomplete, lacking a binding pocket for a nucleotide base. In the second form, residues from the second subunit complete the nucleotide-binding site. This suggests that the two dimer architectures observed in the crystal structures correspond to a free and a nucleotide-bound form of YeaZ. A multiple sequence alignment of YeaZ proteins from different bacteria allowed us to identify a large conserved hydrophobic patch on the protein surface that becomes exposed upon nucleotide-driven dimer re-arrangement. We hypothesize that the transition between two dimer architectures represents the transition between the ‘on’ and ‘off’ states of YeaZ. The effect of this transition is to alternately expose and bury a docking site for the partner protein YgjD. Conclusions/Significance: This paper provides the first structural insight into the putative mechanism of nucleotide regulation of YeaZ through dimer reorganization. Our analysis suggests that nucleotide binding to YeaZ may act as a regulator or switch that changes YeaZ shape, allowing it to switch partners between YjeE and YgjD.Inci Aydin, Yumiko Saijo-Hamano, Keiichi Namba, Connor Thomas and Anna Roujeinikov

Detection of serum MMP-7 and MMP-9 in cholangiocarcinoma patients: evaluation of diagnostic accuracy

<p>Abstract</p> <p>Background</p> <p>Cholangiocarcinoma is an aggressive tumor with a tendency for local invasion and distant metastases. Timely diagnosis is very important because surgical resection (R0) remains the only hope for a cure. However, at present, there is no available tumor marker that can differentiate cholangiocarcinoma from benign bile duct disease. Previous studies have demonstrated that matrix metalloproteinase (MMP)-7 and MMP-9 are frequently expressed in cholangiocarcinoma specimens.</p> <p>Methods</p> <p>This study was designed to determine whether the serum levels of MMP-7 and MMP-9 can discriminate cholangiocarcinoma patients from benign biliary tract disease patients in comparison to carcinoembryonic antigen (CEA) and carbohydrate antigen 19-9 (CA19-9). We measured the level of CEA, CA19-9, MMP-7 and MMP-9 in the serum of 44 cholangiocarcinoma and 36 benign biliary tract diseases patients.</p> <p>Results</p> <p>Among the serum levels of CEA, CA19-9, MMP-7 and MMP-9, only the serum MMP-7 level was significantly higher in the patients with cholangiocarcinoma (8.9 ± 3.43 ng/ml) compared to benign biliary tract disease patients (5.9 ± 3.03 ng/ml) (<it>p </it>< 0.001). An receiver operating characteristic (ROC) curve analysis revealed that the detection of the serum MMP-7 level is reasonably accurate in differentiating cholangiocarcinoma from benign biliary tract disease patients (area under curve = 0.73; 95% CI = 0.614–0.848). While the areas under the curve of the ROC curves for CEA, CA19-9 and MMP-9 were 0.63 (95% CI = 0.501–0.760), 0.63 (95% CI = 0.491–0.761) and 0.59 (95% CI = 0.455–0.722), respectively.</p> <p>Conclusion</p> <p>Serum MMP-7 appears to be a valuable diagnostic marker in the discrimination of cholangiocarcinoma from benign biliary tract disease. Further prospective studies for serum MMP-7 measurement should be carried out to further investigate the potential of this molecule as a biomarker of cholangiocarcinoma.</p

Assessing Conservation Values: Biodiversity and Endemicity in Tropical Land Use Systems

Despite an increasing amount of data on the effects of tropical land use on continental forest fauna and flora, it is debatable whether the choice of the indicator variables allows for a proper evaluation of the role of modified habitats in mitigating the global biodiversity crisis. While many single-taxon studies have highlighted that species with narrow geographic ranges especially suffer from habitat modification, there is no multi-taxa study available which consistently focuses on geographic range composition of the studied indicator groups. We compiled geographic range data for 180 bird, 119 butterfly, 204 tree and 219 understorey plant species sampled along a gradient of habitat modification ranging from near-primary forest through young secondary forest and agroforestry systems to annual crops in the southwestern lowlands of Cameroon. We found very similar patterns of declining species richness with increasing habitat modification between taxon-specific groups of similar geographic range categories. At the 8 km2 spatial level, estimated richness of endemic species declined in all groups by 21% (birds) to 91% (trees) from forests to annual crops, while estimated richness of widespread species increased by +101% (trees) to +275% (understorey plants), or remained stable (- 2%, butterflies). Even traditional agroforestry systems lost estimated endemic species richness by - 18% (birds) to - 90% (understorey plants). Endemic species richness of one taxon explained between 37% and 57% of others (positive correlations) and taxon-specific richness in widespread species explained up to 76% of variation in richness of endemic species (negative correlations). The key implication of this study is that the range size aspect is fundamental in assessments of conservation value via species inventory data from modified habitats. The study also suggests that even ecologically friendly agricultural matrices may be of much lower value for tropical conservation than indicated by mere biodiversity value

Agreement on Web-based Diagnoses and Severity of Mental Health Problems in Norwegian Child and Adolescent Mental Health Services

Objective: This study examined the agreement between diagnoses and severity ratings assigned by clinicians using a structured web-based interview within a child and adolescent mental health outpatient setting. Method: Information on 100 youths was obtained from multiple informants through a web-based Development and Well-Being Assessment (DAWBA). Based on this information, four experienced clinicians independently diagnosed (according to the International Classification of Diseases Revision 10) and rated the severity of mental health problems according to the Health of the Nation Outcome Scales for Children and Adolescents (HoNOSCA) and the Children’s Global Assessment Scale (C-GAS). Results: Agreement for diagnosis was κ=0.69-0.82. Intra-class correlation for single measures was 0.78 for HoNOSCA and 0.74 for C-GAS, and 0.93 and 0.92, respectively for average measures. Conclusions: Agreement was good to excellent for all diagnostic categories. Agreement for severity was moderate, but improved to substantial when the average of the ratings given by all clinicians was considered. Therefore, we conclude that experienced clinicians can assign reliable diagnoses and assess severity based on DAWBA data collected online