Barriers and facilitators to implementation of a home-based cardiac rehabilitation programme for patients with heart failure in the NHS: a mixed-methods study.

OBJECTIVES: This study aimed to identify barriers to, and facilitators of, implementation of the Rehabilitation EnAblement in CHronic Heart Failure (REACH-HF) programme within existing cardiac rehabilitation services, and develop and refine the REACH-HF Service Delivery Guide (an implementation guide cocreated with healthcare professionals). REACH-HF is an effective and cost-effective 12-week home-based cardiac rehabilitation programme for patients with heart failure. SETTING/PARTICIPANTS: In 2019, four early adopter 'Beacon Sites' were set up to deliver REACH-HF to 200 patients. In 2020, 5 online REACH-HF training events were attended by 85 healthcare professionals from 45 National Health Service (NHS) teams across the UK and Ireland. DESIGN: Our mixed-methods study used in-depth semi-structured interviews and an online survey. Interviews were conducted with staff trained specifically for the Beacon Site project, identified by opportunity and snowball sampling. The online survey was later offered to subsequent NHS staff who took part in the online REACH-HF training. Normalisation Process Theory was used as a theoretical framework to guide data collection/analysis. RESULTS: Seventeen healthcare professionals working at the Beacon Sites were interviewed and 17 survey responses were received (20% response rate). The identified barriers and enablers included, among many, a lack of resources/commissioning, having interest in heart failure and working closely with the clinical heart failure team. Different implementation contexts (urban/rural), timing (during the COVID-19 pandemic) and factors outside the healthcare team/system (quality of the REACH-HF training) were observed to negatively or positively impact the implementation process. CONCLUSIONS: The findings are highly relevant to healthcare professionals involved in planning, delivering and commissioning of cardiac rehabilitation for patients with heart failure. The study's main output, a refined version of the REACH-HF Service Delivery Guide, can guide the implementation process (eg, designing new care pathways) and provide practical solutions to overcoming common implementation barriers (eg, through early identification of implementation champions).

A pragmatic effectiveness-implementation study comparing trial evidence with routinely collected outcome data for patients receiving the REACH-HF home-based cardiac rehabilitation programme.

BACKGROUND: Cardiac rehabilitation for heart failure continues to be greatly underused worldwide despite being a Class I recommendation in international clinical guidelines and uptake is low in women and patients with mental health comorbidities. METHODS: Rehabilitation EnAblement in CHronic Heart Failure (REACH-HF) programme was implemented in four UK National Health Service early adopter sites ('Beacon Sites') between June 2019 and June 2020. Implementation and patient-reported outcome data were collected across sites as part of the National Audit of Cardiac Rehabilitation. The change in key outcomes before and after the supervised period of REACH-HF intervention across the Beacon Sites was assessed and compared to those of the intervention arm of the REACH-HF multicentre trial. RESULTS: Compared to the REACH-HF multicentre trial, patients treated at the Beacon Site were more likely to be female (33.8% vs 22.9%), older (75.6 vs 70.1), had a more severe classification of heart failure (26.5% vs 17.7%), had poorer baseline health-related quality of life (MLHFQ score 36.1 vs 31.4), were more depressed (HADS score 6.4 vs 4.1) and anxious (HADS score 7.2 vs 4.7), and had lower exercise capacity (ISWT distance 190 m vs 274.7 m). There appeared to be a substantial heterogeneity in the implementation process across the four Beacon Sites as evidenced by the variation in levels of patient recruitment, operationalisation of the REACH-HF intervention and patient outcomes. Overall lower improvements in patient-reported outcomes at the Beacon Sites compared to the trial may reflect differences in the population studied (having higher morbidity at baseline) as well as the marked challenges in intervention delivery during the COVID-19 pandemic. CONCLUSION: The results of this study illustrate the challenges in consistently implementing an intervention (shown to be clinically effective and cost-effective in a multicentre trial) into real-world practice, especially in the midst of a global pandemic. Further research is needed to establish the real-world effectiveness of the REACH-HF intervention in different populations.

Process evaluation of a randomised pilot trial of home-based rehabilitation compared to usual care in patients with heart failure with preserved ejection fraction and their caregiver's.

BACKGROUND: Whilst almost 50% of heart failure (HF) patients have preserved ejection fraction (HFpEF), evidence-based treatment options for this patient group remain limited. However, there is growing evidence of the potential value of exercise-based cardiac rehabilitation. This study reports the process evaluation of the Rehabilitation Enablement in Chronic Heart Failure (REACH-HF) intervention for HFpEF patients and their caregivers conducted as part of the REACH-HFpEF pilot trial. METHODS: Process evaluation sub-study parallels to a single-centre (Tayside, Scotland) randomised controlled pilot trial with qualitative assessment of both intervention fidelity delivery and HFpEF patients' and caregivers' experiences. The REACH-HF intervention consisted of self-help manual for patients and caregivers, facilitated over 12 weeks by trained healthcare professionals. Interviews were conducted following completion of intervention in a purposeful sample of 15 HFpEF patients and seven caregivers. RESULTS: Qualitative information from the facilitator interactions and interviews identified three key themes for patients and caregivers: (1) understanding their condition, (2) emotional consequences of HF, and (3) responses to the REACH-HF intervention. Fidelity analysis found the interventions to be delivered adequately with scope for improvement in caregiver engagement. The differing professional backgrounds of REACH-HF facilitators in this study demonstrate the possibility of delivery of the intervention by healthcare staff with expertise in HF, cardiac rehabilitation, or both. CONCLUSIONS: The REACH-HF home-based facilitated intervention for HFpEF appears to be a feasible and a well-accepted model for the delivery of rehabilitation, with the potential to address key unmet needs of patients and their caregivers who are often excluded from HF and current cardiac rehabilitation programmes. Results of this study will inform a recently funded full multicentre randomised clinical trial. TRIAL REGISTRATION: ISRCTN78539530 (date of registration 7 July 2015).

Factors influencing implementation of aerobic exercise after stroke: a systematic review.

OBJECTIVES: This systematic review aimed to explore the perspectives of healthcare, exercise, and fitness professionals working with people post-stroke regarding the factors affecting the implementation of aerobic exercise after stroke. DATA SOURCES: OVID SP MEDLINE, OVID SP EMBASE, and CINAHL were searched from inception to December 2018 using a combination of search terms with synonyms of stroke, aerobic exercise and barriers/facilitators. REVIEW METHODS: Studies focusing on the factors affecting implementation of aerobic exercise after stroke from staff perspectives were included with no restriction on the types of study design. For inclusivity, a broad definition of aerobic exercise was used. Review authors independently extracted data from included studies using domains from the Consolidated Framework for Implementation Research, then synthesised using a framework synthesis approach. Retrospective automated screening was conducted using Rayyan software. RESULTS: Twenty studies were included. Four reported on implementation of aerobic exercise, sixteen on general exercise interventions, all post-stroke. Factors identified as influencing implementation of aerobic exercise after stroke included professionals' self-efficacy and knowledge about stroke, patients' needs, communication and collaboration within and between organisations and resources such as equipment, staff and training. CONCLUSIONS: Key factors influencing the implementation of aerobic exercise after stroke included characteristics of the staff and intervention and system-level issues, some of which are modifiable. Further research should evaluate strategies which specifically target these modifiable factors to facilitate implementation in practice.IMPLICATIONS FOR REHABILITATIONAerobic exercise after stroke is an effective intervention but there are challenges to implementation from a staff and system perspective.Any changes to the identified factors should be tailored to suit the staff group and setting.Provision of training and knowledge-sharing could improve staff's confidence in the prescription and delivery of aerobic exercise after stroke though other implementation strategies should also be considered.

Getting evidence into clinical practice: protocol for evaluation of the implementation of a home-based cardiac rehabilitation programme for patients with heart failure.

INTRODUCTION: Cardiac rehabilitation (CR) improves health-related quality of life and reduces hospital admissions. However, patients with heart failure (HF) often fail to attend centre-based CR programmes. Novel ways of delivering healthcare, such as home-based CR programmes, may improve uptake of CR. Rehabilitation EnAblement in CHronic Heart Failure (REACH-HF) is a new, effective and cost-effective home-based CR programme for people with HF. The aim of this prospective mixed-method implementation evaluation study is to assess the implementation of the REACH-HF CR programme in the UK National Health Service (NHS). The specific objectives are to (1) explore NHS staff perceptions of the barriers and facilitators to the implementation of REACH-HF, (2) assess the quality of delivery of the programme in real-life clinical settings, (3) consider the nature of any adaptation(s) made and how they might impact on intervention effectiveness and (4) compare real-world patient outcomes to those seen in a prior clinical trial. METHODS AND ANALYSIS: REACH-HF will be rolled out in four NHS CR centres across the UK. Three healthcare professionals from each site will be trained to deliver the 12-week programme. In-depth qualitative interviews and focus groups will be conducted with approximately 24 NHS professionals involved in delivering or commissioning the programme. Consultations for 48 patients (12 per site) will be audio recorded and scored using an intervention fidelity checklist. Outcomes routinely recorded in the National Audit of Cardiac Rehabilitation will be analysed and compared with outcomes from a recent randomised controlled trial: the Minnesota Living with HF Questionnaire and exercise capacity (Incremental Shuttle Walk Test). Qualitative research findings will be mapped onto the Normalisation Process Theory framework and presented in the form of a narrative synthesis. Results of the study will inform national roll-out of REACH-HF. ETHICS AND DISSEMINATION: The study (IRAS 261723) has received ethics approval from the South Central (Hampshire B) Research Ethics Committee (19/SC/0304). Written informed consent will be obtained from all health professionals and patients participating in the study. The research team will ensure that the study is conducted in accordance with the Declaration of Helsinki, the Data Protection Act 2018, General Data Protection Regulations and in accordance with the Research Governance Framework for Health and Social Care (2005). Findings will be published in scientific peer-reviewed journals and presented at local, national and international meetings to publicise and explain the research methods and findings to key audiences to facilitate the further uptake of the REACH-HF intervention. TRIAL REGISTRATION: ISRCTN86234930.

Outcome measures in a combined exercise rehabilitation programme for adults with COPD and chronic heart failure: A preliminary stakeholder consensus event.

Combined exercise rehabilitation for chronic obstructive pulmonary disease (COPD) and chronic heart failure (CHF) is potentially attractive. Uncertainty remains as to the baseline profiling assessments and outcome measures that should be collected within a programme. Current evidence surrounding outcome measures in cardiac and pulmonary rehabilitation were presented by experts at a stakeholder consensus event and all stakeholders (n = 18) were asked to (1) rank in order of importance a list of categories, (2) prioritise outcome measures and (3) prioritise baseline patient evaluation measures that should be assessed in a combined COPD and CHF rehabilitation programme. The tasks were completed anonymously and related to clinical rehabilitation programmes and associated research. Health-related quality of life, exercise capacity and symptom evaluation were voted as the most important categories to assess for clinical purposes (median rank: 1, 2 and 3 accordingly) and research purposes (median rank; 1, 3 and 4.5 accordingly) within combined exercise rehabilitation. All stakeholders agreed that profiling symptoms at baseline were 'moderately', 'very' or 'extremely' important to assess for clinical and research purposes in combined rehabilitation. Profiling of frailty was ranked of the same importance for clinical purposes in combined rehabilitation. Stakeholders identified a suite of multidisciplinary measures that may be important to assess in a combined COPD and CHF exercise rehabilitation programme.

Caregiver outcomes of the REACH-HF multicentre randomized controlled trial of home-based rehabilitation for heart failure with reduced ejection fraction.

BACKGROUND: Caregivers frequently provide support to people living with long-term conditions. However, there is paucity of evidence of interventions that support caregivers in their role. Rehabilitation EnAblement in Chronic Heart Failure (REACH-HF) is a novel home-based, health-professional-facilitated, self-management programme for patients with heart failure (HF) and their caregivers. METHODS: Based on the random allocation of individual adult patients with reduced ejection fraction (HFrEF) and left ventricular ejection fraction <45% within the past five years, the caregiver of patients was allocated to receive the REACH-HF intervention over 12 weeks (REACH-HF group) or not (control group). Caregiver outcomes were generic health-related quality of life (EQ-5D-5L), Family Caregiver Quality of Life Scale questionnaire (FamQol), Caregiver Burden Questionnaire HF (CBQ-HF), Caregiver Contribution to Self-care of HF Index questionnaire (CC-SCHFI) and Hospital Anxiety and Depression Scale (HADS). Outcomes were compared between groups at 4, 6 and 12 months follow-up. Twenty caregivers receiving REACH-HF were purposively selected for qualitative interviews at 4 and 12 months. RESULTS: Compared with controls (44 caregivers), the REACH-HF group (53 caregivers) had a higher mean CC-SCHFI confidence score at 12 months (57.5 vs 62.8, adjusted mean difference: 9.3, 95% confidence interval: 1.8-16.8, p = 0.016). No significant between group differences were seen in other caregiver outcomes. Qualitative interviews showed that most caregivers who received the REACH-HF intervention made positive changes to how they supported the HF patient they were caring for, and perceived that they had increased their confidence in the caregiver role over time. CONCLUSION: Provision of the REACH-HF intervention for caregivers of HF patients improved their confidence of self-management and was perceived for some to be helpful in supporting their caregiver role.

Proteomic response to linoleic acid hydroperoxide in Saccharomyces cerevisiae.

Yeast AP-1 transcription factor (Yap1p) and the enigmatic oxidoreductases Oye2p and Oye3p are involved in counteracting lipid oxidants and their unsaturated breakdown products. In order to uncover the response to linoleic acid hydroperoxide (LoaOOH) and the roles of Oye2p, Oye3p and Yap1p, we carried out proteomic analysis of the homozygous deletion mutants oye3Δ, oye2Δ and yap1Δ alongside the diploid parent strain BY4743. The findings demonstrate that deletion of YAP1 narrowed the response to LoaOOH, as the number of proteins differentially expressed in yap1Δ was 70% of that observed in BY4743. The role of Yap1p in regulating the major yeast peroxiredoxin Tsa1p was demonstrated by the decreased expression of Tsa1p in yap1Δ. The levels of Ahp1p and Hsp31p, previously shown to be regulated by Yap1p, were increased in LoaOOH-treated yap1Δ, indicating their expression is also regulated by another transcription factor(s). Relative to BY4743, protein expression differed in oye3Δ and oye2Δ under LoaOOH, underscored by superoxide dismutase (Sod1p), multiple heat shock proteins (Hsp60p, Ssa1p, and Sse1p), the flavodoxin-like protein Pst2p and the actin stabiliser tropomyosin (Tpm1p). Proteins associated with glycolysis were increased in all strains following treatment with LoaOOH. Together, the dataset reveals, for the first time, the yeast proteomic response to LoaOOH, highlighting the significance of carbohydrate metabolism, as well as distinction between the roles of Oye3p, Oye2p and Yap1p.

Unravelling the role of protein kinase CK2 in metal toxicity using gene deletion mutants.

Metal ions, biologically essential or toxic, are present in the surrounding environment of living organisms. Understanding their uptake, homeostasis or detoxification is critical in cell biology and human health. In this study, we investigated the role of protein kinase CK2 in metal toxicity using gene deletion strains of Saccharomyces cerevisiae against a panel of six metal ions. The deletion of CKA2, the yeast orthologue of mammalian CK2α', leads to a pronounced resistant phenotype against Zn2+ and Al3+, whilst the deletion of CKB1 or CKB2 results in tolerance to Cr6+ and As3+. The individual deletion mutants of CK2 subunits (CKA1, CKA2, CKB1 and CKB2) did not have any benefit against Co2+ and Cd2+. The metal ion content in the treated cells was then measured by inductively coupled plasma mass spectrometry. Two contrasting findings were obtained for the CKA2 deletion mutant (cka2Δ) against Al3+ or Zn2+. Upon exposure to Al3+, cka2Δ had markedly lower Al3+ content than the wild type and other CK2 mutants, congruous to the resistant phenotype of cka2Δ against Al3+, indicating that CKA2 is responsible for Al3+ uptake. Upon zinc exposure the same mutant showed similar Zn2+ content to the wild type and cka1Δ. Strikingly, the selective inhibitor of CK2 TBB (4,5,6,7-tetrabromo-1H-benzotriazole) abolished the resistant phenotype of cka2Δ against Zn2+. Hence, the CK2 subunit CKA1 plays a key role in Zn2+ sequestration of the cell. Given that both zinc and CK2 are implicated in cancer development, the findings herein are of significance to cancer research and anticancer drug development.

Revelation of molecular basis for chromium toxicity by phenotypes of Saccharomyces cerevisiae gene deletion mutants.

Chromium toxicity is increasingly relevant to living organisms such as humans, due to the environmental contamination of chromium and the application of stainless steel-based medical devices like hip prostheses. Despite the investigations in past years, the molecular details for chromium toxicity remain to be delineated. In this study, we seek to gain insights into the molecular aspects of chromium toxicity by screening a genome-wide deletion set of individual genes in Saccharomyces cerevisiae against hexavalent chromium [Cr(vi)] using chromium trioxide. From the primary data collected in this study, two lists of deletion mutants in response to Cr(vi) exposure were obtained, one for the sensitive phenotype and the other for the resistant phenotype. The functional analysis of the genes corresponding to the sensitive mutants reveals the key features of Cr(vi) toxicity, which include genotoxicity, protein damage, disruption of energy and sulfur metabolisms. DNA repair, ubiquitination-mediated protein degradation, iron homeostasis and growth attenuation are the intrinsic facets of the cell's detoxification mechanisms. Protein kinase CK2 is, for the first time, found to be involved in regulating chromium toxicity by reducing the uptake of Cr(vi). Taken together, the findings provide meaningful details into the basic understanding of chromium toxicity in terms of its uptake, modes of action, cellular detoxification and molecular regulatory mechanisms.

Molecular insight into arsenic toxicity via the genome-wide deletion mutant screening of Saccharomyces cerevisiae.

Arsenic is omnipresent in soil, air, food and water. Chronic exposure to arsenic is a serious problem to human health. In-depth understanding of this metalloid's toxicity is a fundamental step towards development of arsenic-free foods and measures for bioremediation. By screening the complete set of gene deletion mutants (4873) of Saccharomyces cerevisiae, this study uncovered 75 sensitive and 39 resistant mutants against arsenite [As(III)]. Functional analysis of the corresponding genes revealed the molecular details for its uptake, toxicity and detoxification. On the basis of the hypersensitivity of yap3Δ, the transcription factor, Yap3p, is for the first time linked to the cell's detoxification against As(III). Apart from confirming the previously described role of the mitogen-activated protein kinase (MAPK) Hog1 pathway in combating arsenic toxicity, the results show that the regulatory subunits (Ckb1p and Ckb2p) of protein kinase CK2 are also involved in the process, suggesting possible crosstalk between the two key protein kinases. The sensitivity to As(III) conferred by deletion of the genes involved in protein degradation and chromatin remodelling demonstrates protein damage is the key mode of toxicity for the metalloid. Furthermore, the resistant phenotype of fps1Δ, snf3Δ and pho81Δ against As(III) links arsenic uptake with the corresponding plasma membrane-bound transporters-aquaglyceroporin (Fps1p), hexose (Snf3p) and phosphate transporters. The molecular details obtained in this screen for As(III) uptake, detoxification and toxicity provide the basis for future investigations into arsenic-related problems in the environment, agriculture and human health.

Identification of aluminium transport-related genes via genome-wide phenotypic screening of Saccharomyces cerevisiae.

Genome-wide screening using gene deletion mutants has been widely carried out with numerous toxicants including oxidants and metal ions. The focus of such studies usually centres on identifying sensitive phenotypes against a given toxicant. Here, we screened the complete collection of yeast gene deletion mutants (5047) with increasing concentrations of aluminium sulphate (0.4, 0.8, 1.6 and 3.2 mM) in order to discover aluminium (Al(3+)) tolerant phenotypes. Fifteen genes were found to be associated with Al(3+) transport because their deletion mutants exhibited Al(3+) tolerance, including lem3Δ, hal5Δ and cka2Δ. Deletion of CKA2, a catalytic subunit of tetrameric protein kinase CK2, gives rise to the most pronounced resistance to Al(3+) by showing significantly higher growth compared to the wild type. Functional analysis revealed that both molecular regulation and endocytosis are involved in Al(3+) transport for yeast. Further investigations were extended to all the four subunits of CK2 (CKA1, CKA2, CKB1 and CKB2) and the other 14 identified mutants under a spectrum of metal ions, including Al(3+), Zn(2+), Mn(2+), Fe(2+), Fe(3+), Co(3+), Ga(3+), Cd(2+), In(3+), Ni(2+) and Cu(2+), as well as hydrogen peroxide and diamide, in order to unravel cross-tolerance amongst metal ions and the effect of the oxidants. Finally, the implication of the findings in Al(3+) transport for the other species like plants and humans is discussed.

Disulfide stress-induced aluminium toxicity: molecular insights through genome-wide screening of Saccharomyces cerevisiae.

Formation of non-native disulfide bonds within or between proteins can lead to protein misfolding and disruption to cellular metabolism. Such a process is defined as disulfide stress. A marked effect of disulfide stress in cells is the elevated accumulation of the intracellular aluminium ion (Al(3+)) accompanied by increased cytotoxicity. To gain an in-depth understanding of the underlying molecular mechanism for disulfide stress-induced aluminium toxicity, the complete set of Saccharomyces cerevisiae deletion mutants (5047) was screened in this study simultaneously with a combination of the two stressors, diamide and Al(3+). The combined treatment of a benign concentration of diamide (0.8 mM) with a sublethal concentration of aluminium sulfate (0.4 mM) revealed 494 sensitive deletion mutants, distinct from those found when either of the single stressors (0.8 mM diamide or 0.4 mM aluminium sulfate) was used. Hierarchical clustering and functional analyses of the 494 mutants sensitive to the dual stressors indicated a significant enrichment in the genes involved in cell wall homeostasis, signaling cascades, secretory transport machinery and detoxification. The results highlight the process of maintaining cell wall integrity as the central response to the combined exposure of diamide and Al(3+), which is mediated by the signaling pathways and transcription activation via Rlm1p and Swi6p for biosynthesis of the essential cell wall components such as glucan and chitin. Sensitivity of mutants associated with endoplasmic reticulum (ER), vesicle and vacuole functions demonstrates that secretory machinery is essential for surviving the stress conditions, probably due to their roles in transporting polysaccharides to the cell wall and detoxification of accumulated Al(3+). Finally, the phenotype of 100 previously uncharacterized genes against the dual stressors will contribute to their eventual functional annotation.

Guided gingival fibroblast attachment to titanium surfaces: an in vitro study.

AIM: To assess the potential of gingival fibroblasts to attach in a predetermined linear orientation to a nano-topography of aligned fibres on titanium surfaces and determine the ability of such cells to deposit aligned collagen fibre matrix. MATERIALS AND METHODS: smooth glass and rough titanium substrates were coated with polytetrafluoroethylene (PTFE) nano-fibres. Ammonia plasma treatment was used to modify the surface chemistry. Human gingival fibroblasts were cultured on substrates and orientation and collagen deposition was assessed. RESULTS: Straight, unidirectional, parallel PTFE nano-fibres were deposited over the titanium features. By 7 days, the majority of cells were observed to orient to untreated fibres despite the presence of competing titanium surface features. On plasma-treated fibre-coated titanium substrates, cell orientation was mixed. On uncoated substrates, the majority of cells oriented to the titanium surface features. On fibre-coated glass substrates, cells oriented themselves with untreated and plasma-treated fibres and secreted collagen in the same direction after 1 week. On uncoated glass substrates, there was no preferred direction of collagen orientation. CONCLUSION: Polytetrafluoroethylene nano-fibres induced cell and collagen orientation. Surface chemistry appeared only to affect cell behaviour at early time points. An implant surface that controls cell orientation may also influence the orientation of collagen, providing improved gingival support.

Delineation of the molecular mechanism for disulfide stress-induced aluminium toxicity.

Following our previous finding that the sulfhydryl-oxidising chemical diamide induced a marked elevation of cellular Al(3+) (Wu et al., Int J Mol Sci, 12:8119-8132, 2011), a further investigation into the underlying molecular mechanism was carried out, using the eukaryotic model organism Saccharomyces cerevisiae. The effects of non-toxic dose of diamide (0.8 mM) and a mild dose of aluminium sulphate (Al(3+)) (0.4 mM) were determined prior to the screening of gene deletion mutants. A total of 81 deletion mutants were selected for this study according to the available screening data against Al(3+) only (Kakimoto et al., BioMetals, 18: 467-474, 2005) and diamide only (Thorpe et al., Proc Natl Acad Sci USA, 101: 6564-6569, 2004). On the basis of our screening data and the cluster analysis, a cluster containing the gene deletions (rpe1∆, sec72∆, pdr5∆ and ric1∆) was found to be specifically sensitive to the mixture of diamide and Al(3+). However gnp1∆, mch5∆ and ccc1∆ mutants were resistant. Dithiothreitol (DTT) and ascorbate markedly reversed the diamide-induced Al(3+) toxicity. Inductively-coupled plasma optical emission spectrometry demonstrated that DTT reduced the intracellular Al(3+) content in diamide/Al(3+)-treated yeast cells six-fold compared to the non-DTT controls. These data together revealed that the pleiotropic drug resistance transporter (Pdr5p) and vacuolar/vesicular transport-related proteins (Ric1p and Sec72p) are the targets of diamide. A dysfunctional membrane-bound Pdr5p terminates the detoxification pathway for Al(3+) at the final step, leading to intracellular Al(3+) accumulation and hence toxicity. As Al(3+) toxicity has been a problem in agriculture and human health, this study has provided a significant step forward in understanding Al(3+) toxicity.

Different reactive oxygen species lead to distinct changes of cellular metal ions in the eukaryotic model organism Saccharomyces cerevisiae.

Elemental uptake and export of the cell are tightly regulated thereby maintaining the ionomic homeostasis. This equilibrium can be disrupted upon exposure to exogenous reactive oxygen species (ROS), leading to reduction or elevation of the intracellular metal ions. In this study, the ionomic composition in the eukaryotic model organism Saccharomyces cerevisiae was profiled using the inductively-coupled plasma optical emission spectrometer (ICP-OES) following the treatment with individual ROS, including hydrogen peroxide, cumen hydroperoxide, linoleic acid hydroperoxide (LAH), the superoxide-generating agent menadione, the thiol-oxidising agent diamide [diazine-dicarboxylic acid-bis(dimethylamide)], dimedone and peroxynitrite. The findings demonstrated that different ROS resulted in distinct changes in cellular metal ions. Aluminium (Al(3+)) level rose up to 50-fold after the diamide treatment. Cellular potassium (K(+)) in LAH-treated cells was 26-fold less compared to the non-treated controls. The diamide-induced Al(3+) accumulation was further validated by the enhanced Al(3+) uptake along the time course and diamide doses. Pre-incubation of yeast with individual elements including iron, copper, manganese and magnesium failed to block diamide-induced Al(3+) uptake, suggesting Al(3+)-specific transporters could be involved in Al(3+) uptake. Furthermore, LAH-induced potassium depletion was validated by a rescue experiment in which addition of potassium increased yeast growth in LAH-containing media by 26% compared to LAH alone. Taken together, the data, for the first time, demonstrated the linkage between ionomic profiles and individual oxidative conditions.

Identification of a protein with antioxidant activity that is important for the protection against beer ageing.

This study was carried out with fresh Australian lager beer which was sampled directly off the production line, the same samples aged for 12 weeks at 30 °C, and the vintage beer which was kept at 20 °C for 5 years. Characteristic Australian lager flavour was maintained in the fresh and vintage beers but was lost in the aged beer. Sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) and free thiol group labelling analyses of beer proteins found that this flavour stability correlated with the presence of an unknown 10 kilodaltons (kDa) protein with a higher level of free thiols. The protein was purified by size-exclusion chromatography, then peptide sequencing and database matching identified it as the barley lipid transfer protein (LTP1). Further characterisation using diphenylpicrylhydrazyl (DPPH) free radical scavenging and a Saccharomyces cerevisiae-based antioxidant screening assay demonstrated that the LTP1 protein was active in DPPH reduction and antioxidant activity. The absence of free thiol in the aged beer indicates that the thiol functional groups within the LTP1 protein were saturated and suggests that it is important in the flavour stability of beer by maintaining reduction capacity during the ageing process.