Structure-activity analysis of diffusible lipid electrophiles associated with phospholipid peroxidation: 4-hydroxynonenal and 4-oxononenal analogues.

Electrophile-mediated disruption of cell signal-ing is involved in the pathogenesis of several diseases including atherosclerosis and cancer. Diffusible and membrane bound lipid electrophiles are known to modify DNA and protein substrates and modulate cellular pathways including ER stress, antioxidant response, DNA damage, heat shock, and apoptosis. Herein we report on a structure-activity relationship for several electrophilic analogues of 4-hydroxynonenal (HNE) and 4-oxononenal (ONE) with regard to toxicity and anti-inflammatory activity. The analogues studied were the oxidation products of HNE and ONE, HNEA/ONEA, the in vivo hydrolysis products of oxidized phosphatidylcholine, COOH-HNE/COOH-ONE, and their methyl esters, COOMe-HNE/ONE. The reactivity of each compound toward N-acetylcysteine was determined and compared to the toxicity toward a human colorectal carcinoma cell line (RKO) and a human monocytic leukemia cell line (THP-1). Further analysis was performed in differentiated THP-1 macrophages to assess changes in macrophage activation and pro-inflammatory signaling in response to each lipid electrophile. HNE/ONE analogues inhibited THP-1 macrophage production of the pro-inflammatory cytokines, IL-6, IL-1ß, and TNFα, after lipopolysaccharide (LPS)/IFNγ activation. Inhibition of cytokine production was observed at submicromolar concentrations of several analogues with as little as 30 min of exposure. Phagocytosis of fluorescent beads was also inhibited by lipid electrophile treatment. Lipid electrophiles related to HNE/ONE are both toxic and anti-inflammatory, but the anti-inflammatory effects in human macrophages are observed at nontoxic concentrations. Neither toxicity nor anti-inflammatory activity are strongly correlated to the reactivity of the model nucleophile, N-acetylcysteine.

Assessment tools for evaluating fitness to drive: a critical appraisal of evidence.

BACKGROUND: Many office-based assessment tools are used by occupational therapists to predict fitness to drive. PURPOSE: To appraise psychometric properties of such tools, specifically predictive validity for on-road performance. METHODS: A literature search was conducted to identify assessment tools and studies involving on-road outcomes (behind-the-wheel evaluation, crashes, traffic violations). Using a standardized appraisal process, reviewers rated each tool's psychometric properties, including its predictive validity with on-road performance. FINDINGS: Seventeen measures met the inclusion criteria. Evidence suggests many tools do not have cutoff scores linked with on-road outcomes, although some had stronger evidence than others. Implications. When making a determination regarding driver fitness, clinicians should consider the psychometric properties of the tool as well as existing evidence concerning its utility in predicting on-road performance. Caution is warranted in using any one office-based tool to predict driving fitness; rather, a multifactorial-based assessment approach that includes physical, cognitive, and visual-perceptual components, is recommended.

Adaptations to support occupational engagement with age-related vision loss: A metasynthesis study.

BACKGROUND.: Age-related vision loss (ARVL) is a progressive process that adversely affects older adults' occupational engagement. As such, older adults often employ a variety of psychological adaptation strategies. PURPOSE.: The purpose of this study was to identify those psychological adaptation strategies employed by older adults aging with ARVL. METHOD.: This metasynthesis searched and identified 21 qualitative articles that described a link between psychological adaptation strategies and occupational engagement. FINDINGS.: The psychological strategies identified were categorized into five themes. The strategies of persisting with hope, positivity, and acceptance and portraying a self-image consistent with independence, competence, and self-reliance were well established in the literature, while other themes were more emerging, such as using humour, relying on religious/spiritual beliefs, and comparing the self to others. IMPLICATIONS.: By understanding the psychological adaptation strategies employed by older adults with ARVL, occupational therapists will be better positioned to guide their clients toward positive adaptive patterns.

Low Vision Rehabilitation, Age-Related Vision Loss, and Risk: A Critical Interpretive Synthesis.

PURPOSE: Given the centrality of risk in geriatric rehabilitation, it is critically important to attend to how conceptualizations of risk shape research, policies, and rehabilitation practices. This paper presents a critical interpretive synthesis (CIS) of literature addressing risk and low vision rehabilitation for older adults with age-related vision loss (ARVL) to identify key guiding assumptions regarding risk and discuss implications for what gets attended to, and not attended to, within research and rehabilitation. DESIGN AND METHODS: This CIS combined guidelines proposed by Dixon-Woods and colleagues (2006-Conducting a critical interpretive synthesis of the literature on access to healthcare by vulnerable groups. BMC Medical Research Methodology, 6, 35) and Alvesson and Sandberg (2011-Generating research questions through problematization. Academy of Management Review, 36, 247-271; 2013-Constructing research questions: Doing interesting research. London: Sage). The iterative review process involved 3 steps: literature search and selection, data extraction, and syntheses to identify boundary assumptions. The dataset included 83 research and practice description articles. RESULTS: Older adults with ARVL were constructed as "at risk" for various adverse outcomes, particularly dependency and self-harm, and as posing risks to others. An epidemiological approach to risk based in assumptions aligned with a technico-scientific perspective was dominant, with risk conceptualized as an embodied, individual-level phenomenon that is to be determined and managed through objective screening and expert monitoring. IMPLICATIONS: Key concerns include a lack of: attention to the tensions created when rehabilitation research and practice attempt to promote independence while simultaneously reducing risk, incorporation of aging adults' perspectives on risk, and analysis of environmental factors that shape risks. Research that starts by valuing older adults' experiences and attends to context can inform rehabilitation practices that support health-promoting, risk-taking, and facilitate collaborative approaches to risk management.

Site-directed mutagenesis to probe catalysis by a Thermobifida fusca beta-1,3-glucanase (Lam81A).

Thermobifida fuscaLam81A is a single domain family-81 beta-1,3-endoglucanase, but no structure is known for this family. Site-directed mutagenesis of 14 conserved residues chosen from sequence alignments was used to identify those with critical roles in catalysis, binding or substrate specificity. Mutant enzymes were assayed for their ability to bind and hydrolyze substrates with various glycosyl linkages. Residues D422, E499 and E503 were candidates for the catalytic acid or catalytic base, and E499 was shown to be the catalytic base by azide rescue. F425 was shown to have a major role in substrate binding possibly mediated by aromatic ring stacking with the sugar substrate. In addition, mutation of D424 to histidine altered the substrate specificity by increasing the rate of cleavage of mixed-linkage beta-glucan and carboxymethyl-cellulose, 60- and 16-fold, respectively, over the wild-type enzyme.

Characterization of a Thermobifida fusca beta-1,3-glucanase (Lam81A) with a potential role in plant biomass degradation.

Thermobifida fusca is a filamentous soil bacterium that plays a major role in the breakdown of plant biomass. In this paper, we report the cloning, expression, purification, and characterization of the T. fusca enzyme, Lam81A. The Carbohydrate Active Enzymes Database (http://afmb.cnrs-mrs.fr/CAZY/) indicates that Lam81A belongs to a relatively uncharacterized family of beta-1,3-glucanases, family GH-81 [Coutinho, P. M., and Henrissat, B. (1999) in Recent Advances in Carbohydrate Bioengineering (Gilbert, H. J., Davies, G., Henrissat, B., and Svensson, B., Eds.) pp 3-12, The Royal Society of Chemistry, Cambridge, U.K.]. Microarray analysis suggests that Lam81A plays a role in biomass degradation, where its natural substrate may be the plant cell wall polysaccharide, callose, which is a polymer of beta-1,3-linked glucose. Characterization of Lam81A has shown that the enzyme is specific for beta-1,3-linked glucose polysaccharides, is endohydrolytic, and utilizes an inverting mechanism for substrate hydrolysis. In addition, the enzyme has a broad pH optimum from 5.5 to 10, a temperature optimum of 50 degrees C, and demonstrates substrate inhibition, as well as showing a high basal level of expression.