Quantification and viability analyses of Pseudokirchneriella subcapitata algal cells using image-based cytometry

This work aims to evaluate the feasibility of using image-based cytometry (IBC) in the analysis of algal cell quantification and viability, using Pseudokirchneriella subcapitata as a cell model. Cell concentration was determined by IBC to be in a linear range between 1×105 and 8×106 cells mL1. Algal viability was defined on the basis that the intact membrane of viable cells excludes the SYTOX Green (SG) probe. The disruption of membrane integrity represents irreversible damage and consequently results in cell death. Using IBC, we were able to successfully discriminate between live (SG-negative cells) and dead algal cells (heat-treated at 65 °C for 60 min; SG-positive cells). The observed viability of algal populations containing different proportions of killed cells was well correlated (R 2=0.994) with the theoretical viability. The validation of the use of this technology was carried out by exposing algal cells of P. subcapitata to a copper stress test for 96 h. IBC allowed us to follow the evolution of cell concentration and the viability of copper-exposed algal populations. This technology overcomes several main drawbacks usually associated with microscopy counting, such as labour-intensive experiments, tedious work and lack of the representativeness of the cell counting. In conclusion, IBC allowed a fast and automated determination of the total number of algal cells and allowed us to analyse viability. This technology can provide a useful tool for a wide variety of fields that utilise microalgae, such as the aquatic toxicology and biotechnology fields.FCT Strategic Project PEst- OE/EQB/LA0023/2013. The post-doctoral grant from FCT (SFRH/BPD/72816/2010)

Intraspecfic variation in cold-temperature metabolic phenotypes of Arabidopsis lyrata ssp petraea

Atmospheric temperature is a key factor in determining the distribution of a plant species. Alongside this, plant populations growing at the margin of their range may exhibit traits that indicate genetic differentiation and adaptation to their local abiotic environment. We investigated whether geographically separated marginal populations of Arabidopsis lyrata ssp. petraea have distinct metabolic phenotypes associated with exposure to cold temperatures. Seeds of A. petraea were obtained from populations along a latitudinal gradient, namely Wales, Sweden and Iceland and grown in a controlled cabinet environment. Mannose, glucose, fructose, sucrose and raffinose concentrations were different between cold treatments and populations, especially in the Welsh population, but polyhydric alcohol concentrations were not. The free amino acid compositions were population specific, with fold differences in most amino acids, especially in the Icelandic populations, with gross changes in amino acids, particularly those associated with glutamine metabolism. Metabolic fingerprints and profiles were obtained. Principal component analysis (PCA) of metabolite fingerprints revealed metabolic characteristic phenotypes for each population and temperature. It is suggested that amino acids and carbohydrates were responsible for discriminating populations within the PCA. Metabolite fingerprinting and profiling has proved to be sufficiently sensitive to identify metabolic differences between plant populations at different atmospheric temperatures. These findings show that there is significant natural variation in cold metabolism among populations of A. l. petraea which may signify plant adaptation to local climates

Cholesterol and the risk of grade-specific prostate cancer incidence: evidence from two large prospective cohort studies with up to 37 years' follow up

<b>Background</b> High cholesterol may be a modifiable risk factor for prostate cancer but results have been inconsistent and subject to potential "reverse causality" where undetected disease modifies cholesterol prior to diagnosis.<p></p> <b>Methods</b> We conducted a prospective cohort study of 12,926 men who were enrolled in the Midspan studies between 1970 and 1976 and followed up to 31st December 2007. We used Cox-Proportional Hazards Models to evaluate the association between baseline plasma cholesterol and Gleason grade-specific prostate cancer incidence. We excluded cancers detected within at least 5 years of cholesterol assay.<p></p> <b>Results</b> 650 men developed prostate cancer in up to 37 years' follow-up. Baseline plasma cholesterol was positively associated with hazard of high grade (Gleason score[greater than or equal to]8) prostate cancer incidence (n=119). The association was greatest among men in the 4th highest quintile for cholesterol, 6.1 to <6.69 mmol/l, Hazard Ratio 2.28, 95% CI 1.27 to 4.10, compared with the baseline of <5.05 mmol/l. This association remained significant after adjustment for body mass index, smoking and socioeconomic status.<p></p> <b>Conclusions</b> Men with higher cholesterol are at greater risk of developing high-grade prostate cancer but not overall risk of prostate cancer. Interventions to minimise metabolic risk factors may have a role in reducing incidence of aggressive prostate cancer

The International comparison of Systems of care and patient outcomes In minor Stroke and Tia (InSIST) study: A community-based cohort study

This is the author accepted manuscript. The final version is available from Sage Publications via the DOI in this record.Rationale: Rapid response by health-care systems for transient ischemic attack and minor stroke (TIA/mS) is recommended to maximize the impact of secondary prevention strategies. The applicability of this evidence to Australian non-hospital-based TIA/mS management is uncertain. Aims: Within an Australian community setting we seek to document processes of care, establish determinants of access to care, establish attack rates and determinants of recurrent vascular events and other clinical outcomes, establish the performance of ABC2-risk stratification, and compare the processes of care and outcomes to those in the UK and New Zealand for TIA/mS. Sample size estimates: Recruiting practices containing approximately 51 full-time-equivalent general practitioners to recruit 100 TIA/mS per year over a four-year study period will provide sufficient power for each of our outcomes. Methods and design: An inception cohort study of patients with possible TIA/mS recruited from 16 general practices in the Newcastle-Hunter Valley-Manning Valley region of Australia. Potential TIA/mS will be ascertained by multiple overlapping methods at general practices, after-hours collaborative, and hospital in-patient and outpatient services. Participants’ index and subsequent clinical events will be adjudicated as TIA/mS or mimics by an expert panel. Study outcomes: Process outcomes—whether the patient was referred for secondary care; time from event to first patient presentation to a health professional; time from event to specialist acute-access clinic appointment; time from event to brain and vascular imaging and relevant prescriptions. Clinical outcomes—recurrent stroke and major vascular events; and health-related quality of life. Discussion: Community management of TIA/mS will be informed by this study.Nationale Health and Medical Research Council (NHMRC

The characteristics of patients with possible Transient Ischemic Attack and Minor Stroke in the Hunter and Manning Valley regions, Australia (the INSIST Study)

This is the final version. Available on open access from the American Academy of Neurology via the DOI in this record. Background: Transient ischemic attack (TIA) and minor stroke (TIAMS) are risk factors for stroke recurrence. Some TIAMS may be preventable by appropriate primary prevention. We aimed to recruit “possible-TIAMS” patients in the INternational comparison of Systems of care and patient outcomes In minor Stroke and TIA (INSIST) study. Methods: A prospective inception cohort study performed across 16 Hunter–Manning region, Australia, general practices in the catchment of one secondary-care acute neurovascular clinic. Possible-TIAMS patients were recruited from August 2012 to August 2016. We describe the baseline demographics, risk factors and pre-event medications of participating patients. Results: There were 613 participants (mean age; 69 ± 12 years, 335 women), and 604 (99%) were Caucasian. Hypertension was the most common risk factor (69%) followed by hyperlipidemia (52%), diabetes mellitus (17%), atrial fibrillation (AF) (17%), prior TIA (13%) or stroke (10%). Eighty-nine (36%) of the 249 participants taking antiplatelet therapy had no known history of cardiovascular morbidity. Of 102 participants with known AF, 91 (89%) had a CHA2DS2-VASc score ≥ 2 but only 47 (46%) were taking anticoagulation therapy. Among 304 participants taking an antiplatelet or anticoagulant agent, 30 (10%) had stopped taking these in the month prior to the index event. Conclusion: This study provides the first contemporary data on TIAMS or TIAMS-mimics in Australia. Community and health provider education is required to address the under-use of anticoagulation therapy in patients with known AF, possibly inappropriate use of antiplatelet therapy and possibly inappropriate discontinuation of antiplatelet or anticoagulation therapy.National Health and Medical Research Counci

Graph Zeta Function and Gauge Theories

Along the recently trodden path of studying certain number theoretic properties of gauge theories, especially supersymmetric theories whose vacuum manifolds are non-trivial, we investigate Ihara's Graph Zeta Function for large classes of quiver theories and periodic tilings by bi-partite graphs. In particular, we examine issues such as the spectra of the adjacency and whether the gauge theory satisfies the strong and weak versions of the graph theoretical analogue of the Riemann Hypothesis.Comment: 35 pages, 7 Figure

The association between levels of alcohol consumption and mental health problems and academic performance among young university students

Purpose: Mental health problems and harmful alcohol consumption have been found to be high among young university students compared to the general population in Australia. This research aimed to investigate the association between levels of drinking and mental health problems and academic performance among university students aged 18 to 24 years. Methods: This study used a quantitative cross-sectional design using data that were collected in 2014 as part of the Youth Alcohol Project (YAP). Participants were randomly drawn from a cross sectional sample of 6000 undergraduate students. Included in the study were only students who were within the age of 18-24, undergraduate, and internally enrolled at the main campus. A total of 2518 undergraduate students aged 18 to 24 years who were enrolled internally at Curtin University Bentley campus were randomly recruited. Data were collected through an online survey. Students were invited to participate in the study through their student email address. The email invitations coincided with the release of semester results to increase the likelihood of students accessing their emails. A further 628 students were randomly recruited through face to face intercept survey during the campus market days. Data were collected by trained research assistants. Validated instruments were used to collected data on levels of alcohol consumption, mental health, and academic performance. Results: A considerable proportion of participants (44%) reported consuming alcohol at hazardous or harmful levels. Multiple logistic regression analysis showed that students who were consuming alcohol at hazardous levels were 1.2 times more likely to report psychological distress than those with lower levels of alcohol consumption (aOR 1.2, 95% CI: 1.1-1.5). In addition, being late for class (aOR 1.7, 95% CI:1.1-2.4), missing classes (aOR = 2.6, 95% CI: 1.9-2.6), inability to concentrate in class (aOR = 2.6, 95% CI: 1.9-3.4), and inability to complete assignments (aOR = 3.5, 95% CI 2.0-6.0) independently predicted for moderate or hazardous alcohol consumption. Conclusion: The study shows that a considerable proportion of undergraduate students at university consume alcohol at hazardous or harmful levels. In addition, high levels of alcohol consumption are associated with poor academic performance and mental health outcomes among students. The results of the study warrant multi-strategy interventions that focus on policy, organisational, educational, environmental and economic strategies that will help to reduce alcohol related harms among university students

The effects of clinical task interruptions on subsequent performance of a medication pre-administration task

There is a surge of research exploring the role of task interruptions in the manifestation of primary task errors both in controlled experimental settings, and safety critical workplaces such as healthcare. Despite such research providing valuable insights into the disruptive properties of task interruption, and, the importance of considering the likely disruptive consequences of clinical task interruptions in healthcare environments, there is an urgent need for an approach that best mimics complex working environments such as healthcare, whilst allowing better control over experimental variables with minimal constraints. We propose that this can be achieved with ecologically sensitive experimental tasks designed to have high levels of experimental control so that theoretical as well as practical parameters and factors can be tested. We developed a theoretically and ecologically informed procedural memory-based task - the CAMROSE Medication Pre-Administration Task. Results revealed significantly more sequence errors were made on low, moderate and high complex conditions compared to no interruption condition. There was no significant difference in non-sequence errors. Findings reveal the importance of developing ecologically valid tasks to explore non-observable characteristics of clinical task interruptions. Both theoretical and possible practical implications are discussed

Survival or Revival: Long-Term Preservation Induces a Reversible Viable but Non-Culturable State in Methane-Oxidizing Bacteria

Knowledge on long-term preservation of micro-organisms is limited and research in the field is scarce despite its importance for microbial biodiversity and biotechnological innovation. Preservation of fastidious organisms such as methane-oxidizing bacteria (MOB) has proven difficult. Most MOB do not survive lyophilization and only some can be cryopreserved successfully for short periods. A large-scale study was designed for a diverse set of MOB applying fifteen cryopreservation or lyophilization conditions. After three, six and twelve months of preservation, the viability (via live-dead flow cytometry) and culturability (via most-probable number analysis and plating) of the cells were assessed. All strains could be cryopreserved without a significant loss in culturability using 1% trehalose in 10-fold diluted TSB (TT) as preservation medium and 5% DMSO as cryoprotectant. Several other cryopreservation and lyophilization conditions, all of which involved the use of TT medium, also allowed successful preservation but showed a considerable loss in culturability. We demonstrate here that most of these non-culturables survived preservation according to viability assessment indicating that preservation induces a viable but non-culturable (VBNC) state in a significant fraction of cells. Since this state is reversible, these findings have major implications shifting the emphasis from survival to revival of cells in a preservation protocol. We showed that MOB cells could be significantly resuscitated from the VBNC state using the TT preservation medium