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1.  Unaccustomed Eccentric Contractions Impair Plasma K+ Regulation in the Absence of Changes in Muscle Na+,K+-ATPase Content 
PLoS ONE  2014;9(6):e101039.
The Na+,K+-ATPase (NKA) plays a fundamental role in the regulation of skeletal muscle membrane Na+ and K+ gradients, excitability and fatigue during repeated intense contractions. Many studies have investigated the effects of acute concentric exercise on K+ regulation and skeletal muscle NKA, but almost nothing is known about the effects of repeated eccentric contractions. We therefore investigated the effects of unaccustomed maximal eccentric knee extensor contractions on K+ regulation during exercise, peak knee extensor muscle torque, and vastus lateralis muscle NKA content and 3-O-MFPase activity. Torque measurements, muscle biopsies, and venous blood samples were taken before, during and up to 7 days following the contractions in six healthy adults. Eccentric contractions reduced peak isometric muscle torque immediately post-exercise by 26±11% and serum creatine kinase concentration peaked 24 h post-exercise at 339±90 IU/L. During eccentric contractions, plasma [K+] rose during Set 1 and remained elevated at ∼4.9 mM during sets 4–10; this was despite a decline in work output by Set 4, which fell by 18.9% at set 10. The rise in plasma [K+].work−1 ratio was elevated over Set 2 from Set 4– Set 10. Eccentric contractions had no effect on muscle NKA content or maximal in-vitro 3-O-MFPase activity immediately post- or up to 7 d post-exercise. The sustained elevation in plasma [K+] despite a decrease in work performed by the knee extensor muscles suggests an impairment in K+ regulation during maximal eccentric contractions, possibly due to increased plasma membrane permeability or to excitation-contraction uncoupling.
PMCID: PMC4069193  PMID: 24959836
2.  Exercise intervention in New Zealand Polynesian peoples with type 2 diabetes: Cultural considerations and clinical trial recommendations 
The Australasian Medical Journal  2012;5(8):429-435.
The Maori and Pacific Islands peoples of New Zealand suffer a greater burden of type 2 diabetes mellitus (T2DM) and associated comorbidities than their European counterparts. Empirical evidence supports the clinical application of aerobic and resistance training for effective diabetes management and potential remission, but few studies have investigated the effectiveness of these interventions in specific ethnic cohorts. We recently conducted the first trial to investigate the effect of prescribed exercise training in Polynesian people with T2DM. This article presents the cultural considerations undertaken to successfully implement the study. The research procedures were accepted and approved by cultural liaisons and potential participants. The approved methodology involved a trial evaluating and comparing the effects of two, 16-week exercise regimens (i.e. aerobic training and resistance training) on glycosylated haemoglobin (HbA1c), related diabetes markers (i.e. insulin resistance, blood lipids, relevant cytokines and anthropometric and hemodynamic indices) and health-related quality of life. Future exercise-related research or implementation strategies in this cohort should focus on cultural awareness and techniques to enhance participation and compliance. Our approach to cultural consultation could be considered by researchers undertaking trials in this and other ethnic populations suffering an extreme burden of T2DM, including indigenous Australians and Americans.
PMCID: PMC3442187  PMID: 23024717
Resistance; Aerobic; Obesity; Maori; Pacific Islands; Polynesia; Ethnic; High-Risk
3.  Mortality in dialysis patients may not be associated with ESA dose: a 2-year prospective observational study 
BMC Nephrology  2012;13:40.
Anaemia of chronic kidney disease increases the risk of death and adverse events, but can be managed using erythropoiesis stimulating agents (ESAs). However, recent evidence suggests that targeting a higher haemoglobin concentration ([Hb]) increases mortality risk, and both higher [Hb] targets and ESA doses have been implicated. Nonetheless, a causative role has not been demonstrated, and this potential relationship requires further appraisal in such a complex patient group.
The relationship between the haematopoietic response to ESAs and patient survival in 302 stable, prevalent dialysis patients was explored in a prospective, single-centre study. Clinical and laboratory parameters influencing mortality and ESA resistance were analysed. Patients were stratified into 5 groups, according to their [Hb] and ESA dosage, and were followed for 2 years.
Little difference in co-morbidities between groups was identified. 73 patients died and 36 were transplanted. Initial analysis suggested a direct relationship between mortality and ESA dosage. However, Cox proportional hazards multivariate analysis demonstrated mortality risk was associated only with age (adjusted HR per year: 1.061, 95% CI 1.031-1.092), dialysis duration (adjusted HR: 1.010, 95% CI 1.004-1.016), peripheral vascular disease (adjusted HR: 1.967, 95% CI 1.083-3.576) and CRP (adjusted HR: 1.024, 95% CI 1.011-1.039). Mortality was increased in patients poorly responsive to ESAs (55.5%).
ESA dose does not appear to contribute substantially to mortality risk in dialysis patients. Instead, age and co-morbidities appear to be the critical determinants. A poor response to ESAs is a marker of overall poor health status.
PMCID: PMC3468396  PMID: 22702540
Haemoglobin; ESA; Dialysis; Prevalent; Mortality

Results 1-3 (3)