Minimal attachment of Pseudomonas aeruginosa to DNA modified surfaces

© 2018 Author(s). Extracellular deoxyribonucleic acid (eDNA) exists in biological environments such as those around medical implants since prokaryotic or eukaryotic cells can undergo processes such as autolysis, necrosis, and apoptosis. For bacteria, eDNA has been shown to be involved in biofilm formation and gene transfer and acts as a nutrient source. In terms of biofilm formation, eDNA in solution has been shown to be very important in increasing attachment; however, very little is known about the role played by surface immobilized eDNA in initiating bacterial attachment and whether the nature of a DNA layer (physically adsorbed or covalently attached, and molecular weight) influences biofilm formation. In this study, the authors shed light on the role that surface attached DNA plays in the early biofilm formation by using Si wafers (Si) and allylamine plasma polymer (AAMpp) coated Si wafers to adsorb and covalently immobilize salmon sperm DNA of three different molecular weights. Pseudomonas aeruginosa was chosen to study the bacterial interactions with these DNA functionalized surfaces. Characterization of surface chemistry and imaging of attached bacteria were performed via x-ray photoelectron spectroscopy (XPS), scanning electron microscopy, and epi-fluorescence microscopy. XPS results confirmed the successful grafting of DNA on the AAMpp and Si surfaces, and surprisingly the results showed that the surface attached DNA actually reduced initial bacterial attachment, which was contrary to the initial hypothesis. This adds speculation about the specific role played by DNA in the dynamics of how it influences biofilm formation, with the possibility that it could actually be used to make bacterial resistant surfaces

Structural, item, and test generalizability of the psychopathology checklist - revised to offenders with intellectual disabilities

The Psychopathy Checklist–Revised (PCL-R) is the most widely used measure of psychopathy in forensic clinical practice, but the generalizability of the measure to offenders with intellectual disabilities (ID) has not been clearly established. This study examined the structural equivalence and scalar equivalence of the PCL-R in a sample of 185 male offenders with ID in forensic mental health settings, as compared with a sample of 1,212 male prisoners without ID. Three models of the PCL-R’s factor structure were evaluated with confirmatory factor analysis. The 3-factor hierarchical model of psychopathy was found to be a good fit to the ID PCL-R data, whereas neither the 4-factor model nor the traditional 2-factor model fitted. There were no cross-group differences in the factor structure, providing evidence of structural equivalence. However, item response theory analyses indicated metric differences in the ratings of psychopathy symptoms between the ID group and the comparison prisoner group. This finding has potential implications for the interpretation of PCL-R scores obtained with people with ID in forensic psychiatric settings

Association between cognitive performance and cortical glucose metabolism in patients with mild Alzheimer's disease

Background: Neuronal and synaptic function in Alzheimer's disease (AD) is measured in vivo by glucose metabolism using positron emission tomography (PET). Objective: We hypothesized that neuronal activation as measured by PET is a more sensitive index of neuronal dysfunction than activity during rest. We investigated if the correlations between dementia severity as measured with the Mini Mental State Examination (MMSE) and glucose metabolism are an artifact of brain atrophy. Method: Glucose metabolism was measured using {[}F-18]fluorodeoxyglucose PET during rest and activation due to audiovisual stimulation in 13 mild to moderate AD patients (MMSE score >= 17). PET data were corrected for brain atrophy. Results: In the rest condition, glucose metabolism was correlated with the MMSE score primarily within the posterior cingulate and parietal lobes. For the activation condition, additional correlations were within the primary and association audiovisual areas. Most local maxima remained significant after correcting for brain atrophy. Conclusion: PET activity measured during audiovisual stimulation was more sensitive to functional alterations in glucose metabolism in AD patients compared to the resting PET. The association between glucose metabolism and MMSE score was not dependent on brain atrophy. Copyright (C) 2005 S. Karger AG, Basel

Measuring and Predicting Individual Differences in Executive Functions at 14 Months: A Longitudinal Study.

This study of 195 (108 boys) children seen twice during infancy (Time 1: 4.12 months; Time 2: 14.42 months) aimed to investigate the associations between and infant predictors of executive function (EF) at 14 months. Infants showed high levels of compliance with the EF tasks at 14 months. There was little evidence of cohesion among EF tasks but simple response inhibition was related to performance on two other EF tasks. Infant attention (but not parent-rated temperament) at 4 months predicted performance on two of the four EF tasks at 14 months. Results suggest that EF skills build on simpler component skills such as attention and response inhibition.ESR

Differential Item Functioning on Antisocial Behavior Scale Items for Adolescents and Young Adults from Single-Parent and Two-Parent Families

We investigated measurement equivalence in two antisocial behavior scales (i.e., one scale for adolescents and a second scale for young adults) by examining differential item functioning (DIF) for respondents from single-parent (n = 109) and two-parent families (n = 447). Even though one item in the scale for adolescents and two items in the scale for young adults showed significant DIF, the two scales exhibited non-significant differential test functioning (DTF). Both uniform and nonuniform DIF were investigated and examples of each type were identified. Specifically, uniform DIF was exhibited in the adolescent scale whereas nonuniform DIF was shown in the young adult scale. Implications of DIF results for assessment of antisocial behavior, along with strengths and limitations of the study, are discussed

Curtailment and Stochastic Curtailment to Shorten the CES-D

The Center for Epidemiologic Studies-Depression (CES-D) scale is a well-known self-report instrument that is used to measure depressive symptomatology. Respondents who take the full-length version of the CES-D are administered a total of 20 items. This article investigates the use of curtailment and stochastic curtailment (SC), two sequential analysis methods that have recently been proposed for health questionnaires, to reduce the respondent burden associated with taking the CES-D. A post hoc simulation based on 1,392 adolescents' responses to the CES-D was used to compare these methods with a previously proposed computerized adaptive testing (CAT) approach. Curtailment lowered average test lengths by as much as 22% while always matching the classification decision of the full-length CES-D. SC and CAT achieved further reductions in average test length, with SC's classifications exhibiting more concordance with the full-length CES-D than do CAT's. Advantages and disadvantages of each method are discussed. © The Author(s) 2012

Increased efficacy for in-house validation of real-time PCR GMO detection methods

To improve the efficacy of the in-house validation of GMO detection methods (DNA isolation and real-time PCR, polymerase chain reaction), a study was performed to gain insight in the contribution of the different steps of the GMO detection method to the repeatability and in-house reproducibility. In the present study, 19 methods for (GM) soy, maize canola and potato were validated in-house of which 14 on the basis of an 8-day validation scheme using eight different samples and five on the basis of a more concise validation protocol. In this way, data was obtained with respect to the detection limit, accuracy and precision. Also, decision limits were calculated for declaring non-conformance (>0.9%) with 95% reliability. In order to estimate the contribution of the different steps in the GMO analysis to the total variation variance components were estimated using REML (residual maximum likelihood method). From these components, relative standard deviations for repeatability and reproducibility (RSDr and RSDR) were calculated. The results showed that not only the PCR reaction but also the factors ‘DNA isolation’ and ‘PCR day’ are important factors for the total variance and should therefore be included in the in-house validation. It is proposed to use a statistical model to estimate these factors from a large dataset of initial validations so that for similar GMO methods in the future, only the PCR step needs to be validated. The resulting data are discussed in the light of agreed European criteria for qualified GMO detection methods