Browsing by Author "Palmer BR"

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    ACE and UCP2 gene polymorphisms and their association with baseline and exercise-related changes in the functional performance of older adults
    (PeerJ Inc., 28/05/2015) Keogh JWL; Palmer BR; Taylor D; Kilding AE
    Maintaining high levels of physical function is an important aspect of successful ageing. While muscle mass and strength contribute to functional performance in older adults, little is known about the possible genetic basis for the heterogeneity of physical function in older adults and in how older adults respond to exercise. Two genes that have possible roles in determining levels of muscle mass, strength and function in young and older adults are angiotensin-converting enzyme (ACE) and mitochondrial uncoupling protein 2 (UCP2). This study examined whether polymorphisms in these two individual genes were associated with baseline functional performance levels and/or the training-related changes following exercise in previously untrained older adults. Five-eight Caucasian older adults (mean age 69.8 years) with no recent history of resistance training enrolled in a 12 week program of resistance, balance and cardiovascular exercises aimed at improving functional performance. Performance in 6 functional tasks was recorded at baseline and after 12 weeks. Genomic DNA was assayed for the ACE intron 16 insertion/deletion (I/D) and the UCP2 G-866A polymorphism. Baseline differences among genotype groups were tested using analysis of variance. Genotype differences in absolute and relative changes in physical function among the exercisers were tested using a general linear model, adjusting for age and gender. The genotype frequencies for each of the studied polymorphisms conformed to the Hardy-Weinberg equilibrium. The ACE I/D genotype was significantly associated with mean baseline measures of handgrip strength (II 30.9 ± 3.01 v. ID 31.7 ± 1.48 v. DD 29.3 ± 2.18 kg, p < 0.001), 8ft Up and Go time (II 6.45 ± 0.48 v. ID/DD 4.41 ± 0.19 s, p < 0.001) and 6 min walk distance (II 458 ± 28.7 v. ID/DD 546 ± 12.1m, p = 0.008). The UCP2 G-866A genotype was also associated with baseline 8ft Up and Go time (GG 5.45 ± 0.35 v. GA 4.47 ± 0.26 v. AA 3.89 ± 0.71 s, p = 0.045). After 12 weeks  How to cite this article Keogh et al. (2015), ACE and UCP2 gene polymorphisms and their association with baseline and exercise-related changes in the functional performance of older adults. PeerJ 3:e980; DOI 10.7717/peerj.980  of training, a significant difference between UCP2 G-886A genotype groups for change in 8ft Up and Go time was detected (GG −0.68 ± 0.17 v. GA −0.10 ± 0.14 v. AA +0.05 ± 0.31 s, p = 0.023). While several interesting and possibly consistent associations with older adults’ baseline functional performance were found for the ACE and UCP2 polymorphisms, we found no strong evidence of genetic associations with exercise responses in this study. The relative equivalence of some of these training-response findings to the literature may have reflected the current study’s focus on physical function rather than just strength, the relatively high levels of baseline function for some genotype groups as well as the greater statistical power for detecting baseline differences than the training-related changes.
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    Co-Selection of Bacterial Metal and Antibiotic Resistance in Soil Laboratory Microcosms.
    (18/04/2023) Heydari A; Kim ND; Biggs PJ; Horswell J; Gielen GJHP; Siggins A; Taylor MD; Bromhead C; Palmer BR
    Accumulation of heavy metals (HMs) in agricultural soil following the application of superphosphate fertilisers seems to induce resistance of soil bacteria to HMs and appears to co-select for resistance to antibiotics (Ab). This study aimed to investigate the selection of co-resistance of soil bacteria to HMs and Ab in uncontaminated soil incubated for 6 weeks at 25 °C in laboratory microcosms spiked with ranges of concentrations of cadmium (Cd), zinc (Zn) and mercury (Hg). Co-selection of HM and Ab resistance was assessed using plate culture on media with a range of HM and Ab concentrations, and pollution-induced community tolerance (PICT) assays. Bacterial diversity was profiled via terminal restriction fragment length polymorphism (TRFLP) assay and 16S rDNA sequencing of genomic DNA isolated from selected microcosms. Based on sequence data, the microbial communities exposed to HMs were found to differ significantly compared to control microcosms with no added HM across a range of taxonomic levels.
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    Co-selection of Heavy Metal and Antibiotic Resistance in Soil Bacteria from Agricultural Soils in New Zealand
    (MDPI (Basel, Switzerland), 2022-02-04) Heydari A; Kim ND; Horswell J; Gielen G; Siggins A; Taylor M; Bromhead C; Palmer BR
    Accumulation of trace elements (including heavy metals) in soil from usage of superphos-phate fertilisers induces resistance of soil bacteria to trace elements of environmental concern (TE-oEC) and may co‐select for resistance to antibiotics (Ab). This study aimed to investigate selection of co‐resistance of soil bacteria to Cd, Zn and Hg, and Ab in soils with varied management histories. Genetic diversity of these bacteria and horizontal transfer of Cd resistance genes (cadA and czcA) were also investigated. Soils with either pastoral and arable management histories and either high levels of Cd and Zn, or indigenous bush with background levels of these TEoEC from the Waikato region, New Zealand were sampled. Plate culturing with a range of TEoEC and Ab concentrations, Pollution Induced Community Tolerance (PICT) assay, antibiotic sensitivity, terminal restriction fragment length polymorphism (TRFLP) and horizontal gene transfer (HGT) analyses were em-ployed to investigate co‐selection of TEoEC and Ab resistance. Higher levels of bacterial resistance to TEoEC and Ab correlated with higher levels of TEoEC in soil. Bacterial community structures were altered in soils with high TEoEC levels. Cd resistance genes were transferred from donor bacterial isolates, to recipients and the transconjugants also had resistance to Zn and/or Hg and a range of Ab.
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    Effects of selected emerging contaminants found in wastewater on antimicrobial resistance and horizontal gene transfer
    (Elsevier B.V., 2023-08-29) van Hamelsveld S; Jamali-Behnam F; Alderton I; Kurenbach B; McCabe AW; Palmer BR; Gutiérrez-Ginés MJ; Weaver L; Horswell J; Tremblay LA; Heinemann JA
    The widespread use of emerging contaminants (ECs) may be compounding the problem of antibiotic resistance. Various non-antibiotic pollutants have been shown to alter bacterial responses to antibiotics and increase horizontal transfer of antimicrobial resistance (AMR) genes. ECs include components of medicines, foods, disinfectants, personal care products and agrichemicals. ECs concentrate in some environments such as in wastewater, where the pollutants and pathogenic microorganisms mix. We investigated the effects on antibiotic resistance and gene transfer of nine ECs and one commercial product formulation (Roundup). We used the bacterium Salmonella enterica serovar Typhimurium and the antibiotics ampicillin and gentamicin as indicators of the effects of antibiotic-EC co-exposures. We measured intra- (Escherichia coli) and interspecies (E. coli x S. enterica) conjugation frequencies during exposure to ECs. Interestingly, the observed effect could change at different antibiotic concentrations. Exposures to increasing concentrations of ECs was associated with increased conjugative transmission within species, but rarely increased interspecies transmission. We report the first test ever of clotrimazole on AMR and horizontal gene transfer and a newly described effect of dimethyl sulfoxide (DMSO), often used as a solvent for organic compounds.
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    Effects of Whey Protein on Skeletal Muscle Microvascular and Mitochondrial Plasticity Following 10-Weeks of Exercise Training in Men with Type-2 Diabetes
    (Canadian Science Publishing, 2021-08) Gaffney K; Lucero A; Macartney-Coxson D; Clapham J; Whitfield P; Palmer BR; Wakefield S; Faulkner J; Stoner L; Rowlands DS
    Abstract Skeletal muscle microvascular dysfunction and mitochondrial rarefaction feature in type 2 diabetes mellitus (T2DM) linked to low tissue glucose disposal rate (GDR). Exercise training and milk protein supplementation independently promote microvascular and metabolic plasticity in muscle associated with improved nutrient delivery, but combined effects are unknown. In a randomised-controlled trial, 24 men (55.6 y, SD 5.7) with T2DM ingested whey protein drinks (protein/carbohydrate/fat: 20/10/3 g; WHEY) or placebo (carbohydrate/fat: 30/3 g; CON) before/after 45 mixed-mode intense exercise sessions over 10 weeks, to study effects on insulin-stimulated (hyperinsulinemic clamp) skeletal-muscle microvascular blood flow (mBF) and perfusion (near-infrared spectroscopy), and histological, genetic, and biochemical markers (biopsy) of microvascular and mitochondrial plasticity. WHEY enhanced insulin-stimulated perfusion (WHEY-CON 5.6%; 90% CI −0.1, 11.3), while mBF was not altered (3.5%; −17.5, 24.5); perfusion, but not mBF, associated (regression) with increased GDR. Exercise training increased mitochondrial (range of means: 40%–90%) and lipid density (20%–30%), enzyme activity (20%–70%), capillary:fibre ratio (∼25%), and lowered systolic (∼4%) and diastolic (4%–5%) blood pressure, but without WHEY effects. WHEY dampened PGC1α −2.9% (90% compatibility interval: −5.7, −0.2) and NOS3 −6.4% (−1.4, −0.2) expression, but other messenger RNA (mRNA) were unclear. Skeletal muscle microvascular and mitochondrial exercise adaptations were not accentuated by whey protein ingestion in men with T2DM. ANZCTR Registration Number: ACTRN12614001197628. Novelty: • Chronic whey ingestion in T2DM with exercise altered expression of several mitochondrial and angiogenic mRNA. • Whey added no additional benefit to muscle microvascular or mitochondrial adaptations to exercise. • Insulin-stimulated perfusion increased with whey but was without impact on glucose disposal. Résumé Le dysfonctionnement microvasculaire du muscle squelettique et la raréfaction mitochondriale caractérisant le diabète de type 2 (« T2DM ») sont liés à un faible taux d’élimination du glucose tissulaire (« GDR »). L’entraînement physique et la supplémentation en protéines du lait favorisent indépendamment la plasticité microvasculaire et métabolique dans le muscle; cette plasticité est associée à une amélioration de l’apport de nutriments, mais les effets combinés sont inconnus. Dans un essai contrôlé randomisé, 24 hommes (55,6 ans, SD 5,7) aux prises avec le T2DM consomment des boissons protéinées de lactosérum (protéines / glucides / lipides: 20/10/3 g; « WHEY ») ou un placebo (glucides / lipides: 30/3 g; « CON ») avant / après 45 séances d’exercice intense en mode mixte sur 10 semaines, et ce, pour examiner les effets sur le flux sanguin microvasculaire (« mBF ») et la perfusion (spectroscopie proche infrarouge) stimulés par l’insuline (clamp hyperinsulinémique), des variables histologiques, génétiques et des marqueurs biochimiques (biopsie) de la plasticité microvasculaire et mitochondriale. WHEY améliore la perfusion stimulée par l’insuline (WHEY-CON 5,6 %; IC 90 % −0,1, 11,3), tandis que le mBF n’est pas modifié (3,5 %; −17,5, 24,5); la perfusion, mais pas le mBF, est associée (régression) à une augmentation du GDR. L’entraînement à l’exercice augmente la densité mitochondriale (gamme de moyennes: 40-90 %) et lipidique (20−30 %), l’activité enzymatique (20−70 %), le ratio capillaire: fibre (∼25 %) et diminue les pressions systolique (∼4 %) et diastolique (4−5 %), mais sans effets de WHEY. WHEY amortit l’expression de PGC1α −2,9 % (intervalle de compatibilité de 90 % : −5,7, −0,2) et NOS3 −6,4 % (−1,4, −0,2), mais les autres ARN messager (ARNm) ne sont pas clairs. Les adaptations microvasculaires et mitochondriales des muscles squelettiques causées par l’entraînement physique ne sont pas accentuées par la consommation de protéines de lactosérum chez les hommes aux prises avec le T2DM. Numéro d’enregistrement ANXCTR : ACTRN12614001197628. [Traduit par la Rédaction] Les nouveautés: • La consommation prolongée de lactosérum en présence de T2DM combinée à l’entraînement physique modifie l’expression de plusieurs ARNm mitochondriaux et angiogéniques. • Le lactosérum n’ajoute aucun avantage supplémentaire aux adaptations microvasculaires ou mitochondriales musculaires à l’exercice physique. • La perfusion stimulée par l’insuline augmente avec le lactosérum mais n’a pas d’impact sur l’élimination du glucose.
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    Gene variants of the renin angiotensin aldosterone system for risk stratification in heart disease
    (VM Media Group on behalf of the Polskie Towarzystwo Kardiologiczne, 7/06/2021) Palmer BR
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    Genetic polymorphism rs6922269 in the MTHFD1L gene is associated with survival and baseline active vitamin B12 levels in post-acute coronary syndromes patients.
    (2014) Palmer BR; Slow S; Ellis KL; Pilbrow AP; Skelton L; Frampton CM; Palmer SC; Troughton RW; Yandle TG; Doughty RN; Whalley GA; Lever M; George PM; Chambers ST; Ellis C; Richards AM; Cameron VA
    BACKGROUND AND AIMS: The methylene-tetrahydrofolate dehydrogenase (NADP+ dependent) 1-like (MTHFD1L) gene is involved in mitochondrial tetrahydrofolate metabolism. Polymorphisms in MTHFD1L, including rs6922269, have been implicated in risk for coronary artery disease (CAD). We investigated the association between rs6922269 and known metabolic risk factors and survival in two independent cohorts of coronary heart disease patients. METHODS AND RESULTS: DNA and plasma from 1940 patients with acute coronary syndromes were collected a median of 32 days after index hospital admission (Coronary Disease Cohort Study, CDCS). Samples from a validation cohort of 842 patients post-myocardial infarction (PMI) were taken 24-96 hours after hospitalization. DNA samples were genotyped for rs6922269, using a TaqMan assay. Homocysteine and active vitamin B12 were measured by immunoassay in baseline CDCS plasma samples, but not PMI plasma. All cause mortality was documented over follow-up of 4.1 (CDCS) and 8.8 (PMI) years, respectively. rs6922269 genotype frequencies were AA n = 135, 7.0%; GA n = 785, 40.5% and GG n = 1020, 52.5% in the CDCS and similar in the PMI cohort. CDCS patients with AA genotype for rs6922269 had lower levels of co-variate adjusted baseline plasma active vitamin B12 (p = 0.017) and poorer survival than patients with GG or GA genotype (mortality: AA 19.6%, GA 12.0%, GG 11.6%; p = 0.007). In multivariate analysis, rs6922269 genotype predicted survival, independent of established covariate predictors (p = 0.03). However the association between genotype and survival was not validated in the PMI cohort. CONCLUSION: MTHFD1L rs6922269 genotype is associated with active vitamin B12 levels at baseline and may be a marker of prognostic risk in patients with established coronary heart disease.
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    Plasma levels of soluble VEGF receptor isoforms, circulating pterins and VEGF system SNPs as prognostic biomarkers in patients with acute coronary syndromes
    (BioMed Central Ltd, 15/08/2018) Marks ECA; Wilkinson TM; Frampton CM; Skelton L; Pilbrow AP; Yandle TG; Pemberton CJ; Doughty RN; Whalley GA; Ellis CJ; Troughton RW; Owen MC; Pattinson NR; Cameron VA; Richards AM; Gieseg SP; Palmer BR
    BACKGROUND: Development of collateral circulation in coronary artery disease is cardio-protective. A key process in forming new blood vessels is attraction to occluded arteries of monocytes with their subsequent activation as macrophages. In patients from a prospectively recruited post-acute coronary syndromes cohort we investigated the prognostic performance of three products of activated macrophages, soluble vascular endothelial growth factor (VEGF) receptors (sFlt-1 and sKDR) and pterins, alongside genetic variants in VEGF receptor genes, VEGFR-1 and VEGFR-2. METHODS: Baseline levels of sFlt-1 (VEGFR1), sKDR (VEGFR2) and pterins were measured in plasma samples from subgroups (n = 513; 211; 144, respectively) of the Coronary Disease Cohort Study (CDCS, n = 2067). DNA samples from the cohort were genotyped for polymorphisms from the VEGFR-1 gene SNPs (rs748252 n = 2027, rs9513070 n = 2048) and VEGFR-2 gene SNPs (rs2071559 n = 2050, rs2305948 n = 2066, rs1870377 n = 2042). RESULTS: At baseline, levels of sFlt-1 were significantly correlated with age, alcohol consumption, NTproBNP, BNP and other covariates relevant to cardiovascular pathophysiology. Total neopterin levels were associated with alcohol consumption at baseline. 7,8 dihydroneopterin was associated with BMI. The A allele of VEGFR-2 variant rs1870377 was associated with higher plasma sFlt-1 and lower levels of sKDR at baseline. Baseline plasma sFlt-1 was univariately associated with all cause mortality with (p < 0.001) and in a Cox's proportional hazards regression model sFlt-1 and pterins were both associated with mortality independent of established predictors (p < 0.027). CONCLUSIONS: sFlt-1 and pterins may have potential as prognostic biomarkers in acute coronary syndromes patients. Genetic markers from VEGF system genes warrant further investigation as markers of levels of VEGF system components in these patients. TRIAL REGISTRATION: Australian New Zealand Clinical Trials Registry. ACTRN12605000431628 . 16 September 2005, Retrospectively registered.
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    Plasma soluble fms-like tyrosine kinase-1, placental growth factor, and vascular endothelial growth factor system gene variants as predictors of survival in heart failure.
    (John Wiley and Sons Ltd on behalf of European Society of Cardiology, 2024-07-09) Paterson MA; Pilbrow AP; Frampton CM; Cameron VA; Troughton RW; Pemberton CJ; Lund M; Devlin GP; Richards AM; Doughty RN; Palmer BR
    Aims Soluble fms-like tyrosine kinase-1 (sFlt-1) and placental growth factor (PlGF), components of the vascular endothelial growth factor (VEGF) system, play key roles in angiogenesis. Reports of elevated plasma levels of sFlt-1 and PlGF in coronary heart disease and heart failure (HF) led us to investigate their utility, and VEGF system gene single nucleotide polymorphisms (SNPs), as prognostic biomarkers in HF. Methods and results ELISA assays for sFlt-1, PlGF and N-terminal pro-B-type natriuretic peptide (NT-proBNP) were performed on baseline plasma samples from the PEOPLE cohort (n = 890), a study of outcomes among patients after an episode of acute decompensated HF. Eight SNPs potentially associated with sFlt-1 or PlGF levels were genotyped. sFlt-1 and PlGF were assayed in 201 subjects from the Canterbury Healthy Volunteers Study (CHVS) matched to PEOPLE participants. All-cause death was the major endpoint for clinical outcome considered. In PEOPLE participants, mean plasma levels for both sFlt-1 (125 ± 2.01 pg/ml) and PlGF (17.5 ± 0.21 pg/ml) were higher (both p < 0.044) than in the CHVS cohort (81.2 ± 1.31 pg/ml and 15.5 ± 0.32 pg/ml, respectively). sFlt-1 was higher in HF with reduced ejection fraction compared to HF with preserved ejection fraction (p = 0.005). The PGF gene SNP rs2268616 was univariately associated with death (p = 0.016), and was also associated with PlGF levels, as was rs2268614 genotype. Cox proportional hazards modelling (n = 695, 246 deaths) showed plasma sFlt-1, but not PlGF, predicted survival (hazard ratio 6.44, 95% confidence interval 2.57–16.1; p < 0.001) in PEOPLE, independent of age, NT-proBNP, ischaemic aetiology, diabetic status and beta-blocker therapy. Conclusions Plasma sFlt-1 concentrations have potential as an independent predictor of survival and may be complementary to established prognostic biomarkers in HF.
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    The role of emerging organic contaminants in the development of antimicrobial resistance
    (KeAi Communications Co. Ltd. Publishing services by Elsevier BV on behalf of KeAi Communications Co Ltd, 2021-08-05) Alderton I; Palmer BR; Heinemann JA; Pattis I; Weaver L; Gutiérrez-Ginés MJ; Horswell J; Tremblay LA
    Antimicrobial resistance (AMR) threatens human and ecological health worldwide. Unless major changes occur across the human, animal and environmental sectors, the problem will continue to expand. An important component of AMR that deserves greater attention is the influence of emerging organic contaminants (EOCs) – ubiquitous compounds found, amongst others, in pharmaceuticals, personal care products, food, industrial and agricultural products, plastics and building materials. EOCs are widely used and can accumulate in the environment from varied sources, predominantly via waste streams. EOCs can interact with microbial communities potentially leading to the emergence and spread of AMR. Biocides and pharmaceuticals have been demonstrated to promote AMR development. Antimicrobial resistance is a multi-faceted problem that requires input from all sectors, with robust strategies and policies needed to make headway with solving the issues of this important threat.
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    Vascular endothelial growth factor-A promoter polymorphisms, circulating VEGF-A and survival in acute coronary syndromes
    (PLOS, 2021-07-14) Palmer BR; Paterson MA; Frampton CM; Pilbrow AP; Skelton L; Pemberton CJ; Doughty RN; Ellis CJ; Troughton RW; Richards AM; Cameron VA; Zirlik A
    BACKGROUND: Development of a competent collateral circulation in established coronary artery disease is cardio-protective. The vascular endothelial growth factor (VEGF) system plays a key role in this process. We investigated the prognostic performance of circulating VEGF-A and three genetic variants in the VEGFA gene in a clinical coronary cohort. METHODS AND RESULTS: The Coronary Disease Cohort Study (CDCS) recruited 2,140 patients, with a diagnosis of acute coronary syndrome (ACS), after admission to Christchurch or Auckland City Hospitals between July 2002 and January 2009. We present data for 1927 patients from the cohort genotyped for three SNPs in the VEGF-A gene, rs699947 (C-2578A), rs2010963 (C405G) and rs3025039 (C936T). Plasma VEGF-A concentrations were assayed in a subgroup (n = 550) of CDCS patients (geometric mean 36.6 [34.7-38.5] pg/ml). VEGF-A levels correlated with patient heart rate at baseline (p = 0.034). None of rs699947, rs3025039, nor rs2010963 genotypes were significantly associated with VEGF-A levels, but rs3025039 genotype was positively associated with collateral vessels perfusion according to the Rentrop classification (p = 0.01) and baseline natriuretic peptide levels (p<0.05). Survival in the CDCS cohort was independently associated with baseline VEGF-A levels and (in males) with rs699947 genotype. CONCLUSIONS: This study is strongly suggestive that VEGF-A levels have value as a prognostic biomarker in coronary heart disease patients and SNPs in VEGF-A deserve further investigation as prognostic markers and indicators of angiogenic potential influencing the formation of collateral circulation.
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    VEGF-A related SNPs: a cardiovascular context.
    (2023) Meza-Alvarado JC; Page RA; Mallard B; Bromhead C; Palmer BR
    Cardiovascular diseases (CVDs) are the leading cause of death worldwide. Currently, cardiovascular disease risk algorithms play a role in primary prevention. However, this is complicated by a lack of powerfully predictive biomarkers that could be observed in individuals before the onset of overt symptoms. A key potential biomarker for heart disease is the vascular endothelial growth factor (VEGF-A), a molecule that plays a pivotal role in blood vessel formation. This molecule has a complex biological role in the cardiovascular system due to the processes it influences, and its production is impacted by various CVD risk factors. Research in different populations has shown single nucleotide polymorphisms (SNPs) may affect circulating VEGF-A plasma levels, with some variants associated with the development of CVDs, as well as CVD risk factors. This minireview aims to give an overview of the VEGF family, and of the SNPs reported to influence VEGF-A levels, cardiovascular disease, and other risk factors used in CVD risk assessments.