Studies on the properties and the thermal decomposition kinetics of natural rubber prepared with calcium chloride

To evaluate calcium chloride coagulation technology, two kinds of raw natural rubber samples were produced by calcium chloride and acetic acid respectively. Plasticity retention index (PRI), thermal degradation process, thermal degradation kinetics and differential thermal analysis of two samples studied. Furthermore, thermal degradation activation energy, pre-exponential factor and rate constant were calculated. The results show that natural rubber produced by calcium chloride possesses good mechanical property and poor thermo-stability in comparison to natural rubber produced by acetic acid.

The effect of tai chi on psychosocial well-being : a systematic review of randomized controlled trials

Objective : This systematic review aimed to critically appraise published clinical trials designed to assess the effect of Tai Chi on psychosocial well-being.

Data Sources : Databases searched included MEDLINE, CINAHL, EMBASE, HEALT, PsycINFO, CISCOM, the Cochrane Central Register of Controlled Trials of the Cochrane Library, and dissertations and conference proceedings from inception to August 2008.

Review Methods : Methodological quality was assessed using a modified Jadad scale. A total of 15 studies met the inclusion criteria (i.e. English publications of randomized controlled trials with Tai Chi as an intervention and psychological well-being as an outcome measure), of which eight were high quality trials. The psychosocial outcomes measured included anxiety (eight studies), depression (eight studies), mood (four studies), stress (two studies), general mental health three studies), anger, positive and negative effect, self-esteem, life satisfaction, social interaction and self-rated health (one study each).

Results : Tai Chi intervention was found to have a significant effect in 13 studies, especially in the management of depression and anxiety. Although the results seemed to suggest Tai Chi is effective, they should be interpreted cautiously as the quality of the trials varied substantially. Furthermore, significant findings were shown in only six high quality studies. Moreover, significant between group differences after Tai Chi intervention was demonstrated in only one high quality study (the other three significant results were observed in non-high quality studies). Two high quality studies in fact found no significant Tai Chi effects.

Conclusion : It is still premature to make any conclusive remarks on the effect of Tai Chi on psychosocial well-being.

RiboSys, a high-resolution, quantitative approach to measure the in vivo kinetics of pre-mRNA splicing and 3'-end processing in Saccharomyces cerevisiae

We describe methods for obtaining a quantitative description of RNA processing at high resolution in budding yeast. As a model gene expression system, we constructed tetON (for induction studies) and tetOFF (for repression, derepression, and RNA degradation studies) yeast strains with a series of reporter genes integrated in the genome under the control of a tetO7 promoter. Reverse transcription and quantitative real-time-PCR (RT-qPCR) methods were adapted to allow the determination of mRNA abundance as the average number of copies per cell in a population. Fluorescence in situ hybridization (FISH) measurements of transcript numbers in individual cells validated the RT-qPCR approach for the average copy-number determination despite the broad distribution of transcript levels within a population of cells. In addition, RT-qPCR was used to distinguish the products of the different steps in splicing of the reporter transcripts, and methods were developed to map and quantify 3′-end cleavage and polyadenylation. This system permits pre-mRNA production, splicing, 3′-end maturation and degradation to be quantitatively monitored with unprecedented kinetic detail, suitable for mathematical modeling. Using this approach, we demonstrate that reporter transcripts are spliced prior to their 3′-end cleavage and polyadenylation, that is, cotranscriptionally.

Insulin-regulated aminopeptidase : analysis of peptide substrate and inhibitor binding to the catalytic domain

Peptide inhibitors of insulin-regulated aminopeptidase (IRAP) accelerate spatial learning and facilitate memory retention and retrieval by binding competitively to the catalytic site of the enzyme and inhibiting its catalytic activity. IRAP belongs to the M1 family of Zn2+-dependent aminopeptidases characterized by a catalytic domain that contains two conserved motifs, the HEXXH(X)18E Zn2+-binding motif and the GXMEN exopeptidase motif. To elucidate the role of GXMEN in binding peptide substrates and competitive inhibitors, site-directed mutagenesis was performed on the motif. Non-conserved mutations of residues G428, A429 and N432 resulted in mutant enzymes with altered catalytic activity, as well as divergent changes in kinetic properties towards the synthetic substrate leucine β-naphthalamide. The affinities of the IRAP inhibitors angiotensin IV, Nle1-angiotensin IV, and LVV-hemorphin-7 were selectively decreased. Substrate degradation studies using the in vitro substrates vasopressin and Leu-enkephalin showed that replacement of G428 by either D, E or Q selectively abolished the catalysis of Leu-enkephalin, while [A429G]IRAP and [N432A]IRAP mutants were incapable of cleaving both substrates. These mutational studies indicate that G428, A429 and N432 are important for binding of both peptide substrates and inhibitors, and confirm previous results demonstrating that peptide IRAP inhibitors competitively bind to its catalytic site.

Team clinical supervision in acute hospital wards : a feasibility study

Clinical supervision provides a strategy to mitigate nurses’ workplace stress and enhance retention, but the literature provides little guidance about its implementation beyond mental health nursing. This study explored the feasibility of implementing and evaluating ward-based team clinical supervision for general nurses on two separate wards at one public and one private hospital. Nurses completed the Work Environment Questionnaire pre- (n = 36) and post intervention (n = 27), and focus groups (n = 20) explored their perceptions of supervision. Staff were unfamiliar with clinical supervision, so information sessions were required. The questionnaire may not have been suitable to evaluate this type of intervention. Focus group findings revealed that team supervision improved communication, enhanced working relationships, and empowered nurses to challenge existing practices, which had a positive impact on their perceived stress. This study provides insights to guide implementation and evaluation of clinical supervision in acute settings.

The effects of mechanical stress, environment and cathodic protection on the degradation and failure of coatings: An overview

Organic coatings have been used in conjunction with cathodic protection as the most economical method of corrosion protection by the oil and gas pipeline industry. In a bid to prolong the life of the pipelines, the degradation and failure of pipeline coatings under the effects of major influencing factors including mechanical stress, the environmental corrosivity and cathodic protection have been extensively investigated over the past decades. This paper provides an overview of recent research for understanding coating degradation under the effect of these factors, either individually or in combination. Electrochemical impedance spectroscopy remains the primary and the most commonly used technique of studying the degradation of organic coatings, although there have been attempts to use other techniques such as electrochemical polarization (both dynamic and static), electrochemical noise, Scanning Kelvin Probe, Fourier Transform Infrared Spectroscopy, Differential Scanning Calorimetry and Dynamic Mechanical Analyser. Major knowledge and technological gaps in the investigation of the combined effects of mechanical stress, environmental corrosivity and cathodic protection on coating degradation have been identified.

Studies to prevent degradation of recombinant fc-fusion protein expressed in mammalian cell line and protein characterization

Clipping of recombinant proteins is a major issue in animal cell cultures. A recombinant Fc-fusion protein, VEGFR1(D1-D3)-Fc expressed in CHOK1SV GS-KO cells was observed to be undergoing clippings in lab scale cultures. Partial cleaving of expressed protein initiated early on in cell culture and was observed to increase over time in culture and also on storage. In this study, a few parameters were explored in a bid to inhibit clipping in the fusion protein The effects of culture temperature, duration of culture, the addition of an anti-clumping agent, ferric citrate and use of protease inhibitor cocktail on inhibition of proteolysis of the Fc fusion were studied. Lowering of culture temperature from 37 to 30 °C alone appears to be the best solution for reducing protein degradation from the quality, cost and regulatory points of view. The obtained Fc protein was characterized and found to be in its stable folded state, exhibiting a high affinity for its ligand and also biological and functional activities.

Aging studies on conducting polypyrrole

Change of tensile properties, electrical conductivity and microwave shielding of electrochemically synthesized polypyrrole films with time are presented. Highly doped films had good electrical stability, retaining high microwave reflectivity throughout the aging period. Lightly doped films were less stable and partially reflective and absorptive of microwaves. FT-IR spectral observations revealed a progressive increase in intensity of an unsaturated conjugated carbonyl peak, which was not observed in the highly doped films, suggesting that the concentration of the dopant had an influence on the mechanism of degradation of conductivity.

The sources of stress experienced by professional Australian footballers

Previous studies looking at the sources of stress in sport have generally overlooked the unique experiences of professional athletes participating in team sports. This paper describes the results of a qualitative study aimed at identifying the sources of stress experienced by a cross-section of professional Australian footballers. Players from two Australian Football League clubs took part in the study involving in-depth, one-to-one interviews and focus group discussions. The results revealed that players identified sources of stress that went beyond those associated with the competitive event (such as poor performances) and included a lack of feedback, difficulty balancing football and study commitments, and job insecurity. The influence of both competition and non-competition sources of stress parallels previous research involving non-professional athletes and indicates that the entire sporting experience needs to be taken into account when developing stress management strategies.

Building health promoting work settings : identifying the relationship between work characteristics and occupational stress in Australia

Occupational stress is a serious threat to the health of individual workers, their families and the community at large. The settings approach to health promotion offers valuable opportunities for developing comprehensive strategies to prevent and reduce job stress. However, there is evidence that many workplace health promotion programs adopt traditional, lifestyle-oriented strategies when dealing with occupational stress, and ignore the impact that the setting itself has on the health of employees. The aim of the present study was to address two of the barriers to adopting the settings approach; namely the lack of information on how psycho-social work characteristics can influence health, and not having the confidence or knowledge to identify or address organizational-level issues. A comprehensive occupational stress audit involving qualitative and quantitative research methods was undertaken in a small- to medium-sized public sector organization in Australia. The results revealed that the work characteristics ‘social support’ and ‘job control’ accounted for large proportions of explained variance in job satisfaction and psychological health. In addition to these generic variables, several job-specific stressors were found to be predictive of the strain experienced by employees. When coupled with the results of other studies, these findings suggest that work characteristics (particularly control and support) offer valuable avenues for creating work settings that can protect and enhance employee health. The implications of the methods used to develop and complete the stress audit are also discussed.

Role of peer support and emotional expression on posttraumatic stress disorder in student paramedics

This exploratory study contrasted and tested the predictive value of the reverse buffering hypothesis of social support and the information processing model of posttraumatic stress disorder (PTSD) in an investigation of trauma-related symptomatology (TRS) in a single sample of 42 student paramedics. Participants completed several anonymous self-report measures of PTSD symptomatology, peer social support, and attitude toward emotional expression. Regression-based path analyses did not support either theory of PTSD in this population. A path model of PTSD in student paramedics was subsequently developed, indicating that a direct relationship exists between duty-related trauma exposure, dysfunctional peer social support, and students' negative attitudes toward emotional expression. This new model accounted for 30% of the variance in student paramedics' TRS.

Relationship between stress, eating behavior and obesity

Stress is thought to influence human eating behavior and has been examined in animal and human studies. Our understanding of the stress-eating relation is confounded by limitations inherent in the study designs; however, we can make some tentative conclusions that support the notion that stress can influence eating patterns in humans. Stress appears to alter overall food intake in two ways, resulting in under- or overeating, which may be influenced by stressor severity. Chronic life stress seems to be associated with a greater preference for energy- and nutrient-dense foods, namely those that are high in sugar and fat. Evidence from longitudinal studies suggests that chronic life stress may be causally linked to weight gain, with a greater effect seen in men. Stress-induced eating may be one factor contributing to the development of obesity. Future studies that measure biological markers of stress will assist our understanding of the physiologic mechanism underlying the stress-eating relation and how stress might be linked to neurotransmitters and hormones that control appetite.

Heterologous microarray experiments used to identify the early gene response to heat stress in a coral reef fish

Coral reef fishes are expected to experience rising sea surface temperatures due to climate change. How well tropical reef fishes will respond to these increased temperatures and which genes are important in the response to elevated temperatures is not known. Microarray technology provides a powerful tool for gene discovery studies, but the development of microarrays for individual species can be expensive and time-consuming. In this study, we tested the suitability of a Danio rerio oligonucleotide microarray for application in a species with few genomic resources, the coral reef fish Pomacentrus moluccensis. Results from a comparative genomic hybridization experiment and direct sequence comparisons indicate that for most genes there is considerable sequence similarity between the two species, suggesting that the D. rerio array is useful for genomic studies of P. moluccensis. We employed this heterologous microarray approach to characterize the early transcriptional response to heat stress in P. moluccensis. A total of 111 gene loci, many of which are involved in protein processing, transcription, and cell growth, showed significant changes in transcript abundance following exposure to elevated temperatures. Changes in transcript abundance were validated for a selection of candidate genes using quantitative real-time polymerase chain reaction. This study demonstrates that heterologous microarrays can be successfully employed to study species for which specific microarrays have not yet been developed, and so have the potential to greatly enhance the utility of microarray technology to the field of environmental and functional genomics.

SEPS1 protects RAW264.7 cells from pharmacological ER stress agent-induced apoptosis

Selenoprotein S (SEPS1) is a novel endoplasmic reticulum (ER) resident protein and it is known to play an important role in production of inflammatory cytokines. Here, we show evidence that SEPS1 is stimulated by pharmacological ER stress agents in RAW264.7 macrophages as well as other cell types. Overexpression studies reveal a protective action of SEPS1 in macrophages against ER stress-induced cytotoxicity and apoptosis, resulting in promoting cell survival during ER stress. The protective action of SEPS1 is largely dependent on ER stress-mediated cell death signal with less effect on non-ER stress component cell death signals. Conversely, suppression of SEPS1 in macrophages results in sensitization of cells to ER stress-induced cell death. These findings suggest that SEPS1 could be a new ER stress-dependent survival factor that protects macrophage against ER stress-induced cellular dysfunction.

Integrating job stress and social exchange theories to predict employee wellbeing

This research examines the organizational characteristics that contribute to employee wellbeing in public sector agencies that have undergone substantial organizational change. Two studies were undertaken, the first involving 2,466 police officers working in a statebased law enforcement agency, whereas the second comprised 1,010 occupationally diverse employees working in a State Government authority. The research was guided by a theoretical framework that begins with a model underpinning many large-scale job stress investigations—the job strain model (JSM)—and is expanded to incorporate widely used social exchange variables (i.e., psychological contract breach and organizational fairness). The results of hierarchical regression analyses from both studies confirm the value of the JSM. There was also strong support for extending the JSM to include the breach and fairness variables; however, proposed interactions between job demands and organizational fairness failed to add to the explanatory value of the model. The implications of these results particularly for public sector organizations that have undergone extensive reforms consistent with New Public Management are discussed.