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Ang T, Mason SA, Dao GM, Bruce CR, Kowalski GM. The impact of a single dose of whey protein on glucose flux and metabolite profiles in normoglycemic males: insights into glucagon and insulin biology. Am J Physiol Endocrinol Metab 2023; 325:E688-E699. [PMID: 37877796 DOI: 10.1152/ajpendo.00182.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Revised: 10/16/2023] [Accepted: 10/17/2023] [Indexed: 10/26/2023]
Abstract
Protein ingestion concurrently stimulates euglycemic glucagon and insulin secretion, a response that is particularly robust with rapidly absorbing proteins. Previously, we have shown that ingestion of repeated doses of rapidly absorbing whey protein equally stimulated endogenous glucose production (EGP) and glucose disposal (Rd), thus explaining the preservation of euglycemia. Here, we aimed to determine if a smaller single dose of whey could elicit a large enough glucagon and insulin response to stimulate glucose flux. Therefore, in normoglycemic young adult males (n = 10; age ∼26; BMI ∼25), using [6,6-2H2] glucose tracing and quantitative targeted metabolite profiling, we determined the metabolic response to a single 25 g "standard" dose of whey protein. Whey protein ingestion did not alter glycemia, but increased circulating glucagon (peak 4-fold basal), insulin (peak 6-fold basal), amino acids, and urea while also reducing free fatty acid (FFA) and glycerol concentrations. Interestingly, the postprandial insulin response was driven by both a stimulation of insulin secretion and marked reduction in hepatic insulin clearance. Whey protein ingestion resulted in a modest stimulation of EGP and Rd, both peaking at ∼20% above baseline 1 h after protein ingestion. These findings demonstrate that the ingestion of a single standard serving of whey protein can induce a euglycemic glucagon and insulin response that stimulates glucose flux. We speculate on a theory that could potentially explain how glucagon and insulin synergistically provide hardwired control of nitrogen and glucose homeostasis.NEW & NOTEWORTHY Protein ingestion concurrently stimulates glucagon and insulin secretion. Here we show that in normoglycemic males, ingestion of a single "standard" 25 g serving of rapidly absorbing whey protein drives a sufficiently large glucagon and insulin response, such that it simultaneously increases endogenous glucose production and glucose disposal. We speculate on a novel theory that could potentially explain how the antagonistic/synergistic actions of glucagon and insulin simultaneously provide tight control of glucose and nitrogen homeostasis.
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Affiliation(s)
- Teddy Ang
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Science, Deakin University, Geelong, Victoria, Australia
- School of Exercise and Nutrition Science, Deakin University, Geelong, Victoria, Australia
| | - Shaun A Mason
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Science, Deakin University, Geelong, Victoria, Australia
- School of Exercise and Nutrition Science, Deakin University, Geelong, Victoria, Australia
| | - Giang M Dao
- Metabolic Research Unit, School of Medicine, Deakin University, Geelong, Victoria, Australia
| | - Clinton R Bruce
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Science, Deakin University, Geelong, Victoria, Australia
- School of Exercise and Nutrition Science, Deakin University, Geelong, Victoria, Australia
| | - Greg M Kowalski
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Science, Deakin University, Geelong, Victoria, Australia
- Metabolic Research Unit, School of Medicine, Deakin University, Geelong, Victoria, Australia
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Mason SA, Parker L, van der Pligt P, Wadley GD. Vitamin C supplementation for diabetes management: A comprehensive narrative review. Free Radic Biol Med 2023; 194:255-283. [PMID: 36526243 DOI: 10.1016/j.freeradbiomed.2022.12.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Revised: 12/01/2022] [Accepted: 12/05/2022] [Indexed: 12/15/2022]
Abstract
Growing evidence suggests that vitamin C supplementation may be an effective adjunct therapy in the management of people with diabetes. This paper critically reviews the current evidence on effects of vitamin C supplementation and its potential mechanisms in diabetes management. Evidence from meta-analyses of randomized controlled trials (RCTs) show favourable effects of vitamin C on glycaemic control and blood pressure that may be clinically meaningful, and mixed effects on blood lipids and endothelial function. However, evidence is mostly of low evidence certainty. Emerging evidence is promising for effects of vitamin C supplementation on some diabetes complications, particularly diabetic foot ulcers. However, there is a notable lack of robust and well-designed studies exploring effects of vitamin C as a single compound supplement on diabetes prevention and patient-important outcomes (i.e. prevention and amelioration of diabetes complications). RCTs are also required to investigate potential preventative or ameliorative effects of vitamin C on gestational diabetes outcomes. Oral vitamin C doses of 500-1000 mg per day are potentially effective, safe, and affordable for many individuals with diabetes. However, personalisation of supplementation regimens that consider factors such as vitamin C status, disease status, current glycaemic control, vitamin C intake, redox status, and genotype is important to optimize vitamin C's therapeutic effects safely. Finally, given a high prevalence of vitamin C deficiency in patients with complications, it is recommended that plasma vitamin C concentration be measured and monitored in the clinic setting.
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Affiliation(s)
- Shaun A Mason
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, Geelong, Australia.
| | - Lewan Parker
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, Geelong, Australia
| | - Paige van der Pligt
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, Geelong, Australia; Department of Nutrition and Dietetics, Western Health, Footscray, Australia
| | - Glenn D Wadley
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, Geelong, Australia
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Frankenberg NT, Mason SA, Wadley GD, Murphy RM. Skeletal muscle cell-specific differences in type 2 diabetes. Cell Mol Life Sci 2022; 79:256. [PMID: 35460430 PMCID: PMC9035013 DOI: 10.1007/s00018-022-04265-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2021] [Revised: 03/03/2022] [Accepted: 03/20/2022] [Indexed: 11/26/2022]
Abstract
Major stores of glucose are found as glycogen in skeletal muscle and liver. Skeletal muscle is a heterogenous tissue, with cellular metabolic and contractile distinctions dependent on whether the cell (fibre) is slow-twitch (Type I) or fast-twitch (Type II). We hypothesised that proteins important for glycogen metabolism would be differentially abundant between these diverse fibres. We further hypothesised that the cellular location of these proteins would be different in muscle samples between control (CON) and individuals with type 2 diabetes (T2D). We dissected individual muscle fibre segments from vastus lateralis skeletal muscle biopsy samples from CON and T2D and used cell-type-specific approaches to address muscle heterogeneity. We measured glycogen and glycogen-related proteins by immunoblotting techniques. A lower proportion of Type I fibres was found in muscle in T2D compared with CON. AMPK-β2, glycogen branching enzyme (GBE), glycogen debranching enzyme (GDE), and glycogen phosphorylase (GP) were differentially localized between fibre types and in fibres from CON and T2D individuals. A key novel finding was that the majority of glycogen is loosely bound or cytosolic in location in human skeletal muscle. The proportion of this diffusible pool of glycogen was significantly lower in Type I fibres in T2D compared to CON. A hyperinsulinaemic, euglycaemic clamp in people with type 2 diabetes had no effect on the proportion of diffusible glycogen. We identify cell-type as an important consideration when assessing glycogen metabolism in muscle. Our findings demonstrate varying glucose handling abilities in specific muscle fibre types in type 2 diabetes. A model is presented to provide an overview of the cell-specific differences in glycogen metabolism in type 2 diabetes.
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Affiliation(s)
- Noni T Frankenberg
- Department of Biochemistry and Chemistry, La Trobe Institute for Molecular Science, School of Agriculture, Biomedicine and Environment, La Trobe University, Melbourne, 3086, Australia
| | - Shaun A Mason
- Institute for Physical Activity and Nutrition, Deakin University, Burwood, 3125, Australia
| | - Glenn D Wadley
- Institute for Physical Activity and Nutrition, Deakin University, Burwood, 3125, Australia
| | - Robyn M Murphy
- Department of Biochemistry and Chemistry, La Trobe Institute for Molecular Science, School of Agriculture, Biomedicine and Environment, La Trobe University, Melbourne, 3086, Australia.
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McKeegan K, Mason SA, Trewin AJ, Keske MA, Wadley GD, Della Gatta PA, Nikolaidis MG, Parker L. Reactive oxygen species in exercise and insulin resistance: Working towards personalized antioxidant treatment. Redox Biol 2021; 44:102005. [PMID: 34049222 PMCID: PMC8167146 DOI: 10.1016/j.redox.2021.102005] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2021] [Revised: 04/25/2021] [Accepted: 05/06/2021] [Indexed: 12/11/2022] Open
Abstract
Reactive oxygen species (ROS) are well known for their role in insulin resistance and the development of cardiometabolic disease including type 2 diabetes mellitus (T2D). Conversely, evidence supports the notion that ROS are a necessary component for glucose cell transport and adaptation to physiological stress including exercise and muscle contraction. Although genetic rodent models and cell culture studies indicate antioxidant treatment to be an effective strategy for targeting ROS to promote health, human findings are largely inconsistent. In this review we discuss human research that has investigated antioxidant treatment and glycemic control in the context of health (healthy individuals and during exercise) and disease (insulin resistance and T2D). We have identified key factors that are likely to influence the effectiveness of antioxidant treatment: 1) the context of treatment including whether oxidative distress or eustress is present (e.g., hyperglycemia/lipidaemia or during exercise and muscle contraction); 2) whether specific endogenous antioxidant deficiencies are identified (redox screening); 3) whether antioxidant treatment is specifically designed to target and restore identified deficiencies (antioxidant specificity); 4) and the bioavailability and bioactivity of the antioxidant which are influenced by treatment dose, duration, and method of administration. The majority of human research has failed to account for these factors, limiting their ability to robustly test the effectiveness of antioxidants for health promotion and disease prevention. We propose that a modern "redox screening" and "personalized antioxidant treatment" approach is required to robustly explore redox regulation of human physiology and to elicit more effective antioxidant treatment in humans.
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Affiliation(s)
- Kathryn McKeegan
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, Geelong, Australia
| | - Shaun A Mason
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, Geelong, Australia
| | - Adam J Trewin
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, Geelong, Australia
| | - Michelle A Keske
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, Geelong, Australia
| | - Glenn D Wadley
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, Geelong, Australia
| | - Paul A Della Gatta
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, Geelong, Australia
| | - Michalis G Nikolaidis
- Department of Physical Education and Sport Science at Serres, Aristotle University of Thessaloniki, Serres, Greece
| | - Lewan Parker
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, Geelong, Australia.
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Mason SA, Keske MA, Wadley GD. Effects of Vitamin C Supplementation on Glycemic Control and Cardiovascular Risk Factors in People With Type 2 Diabetes: A GRADE-Assessed Systematic Review and Meta-analysis of Randomized Controlled Trials. Diabetes Care 2021; 44:618-630. [PMID: 33472962 DOI: 10.2337/dc20-1893] [Citation(s) in RCA: 56] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Accepted: 10/30/2020] [Indexed: 02/03/2023]
Abstract
BACKGROUND Evidence suggests that vitamin C supplementation could be a potential therapy in type 2 diabetes. However, its effectiveness and evidence quality require further evaluation. PURPOSE To investigate the efficacy of oral vitamin C supplementation in improving glycemic control, cardiovascular risk factors, and oxidative stress in people with type 2 diabetes. DATA SOURCES Databases (PubMed, Embase, Scopus, Cochrane Library) and clinical trial registries were searched for randomized controlled trials up to 8 September 2020. STUDY SELECTION Trials in adults with type 2 diabetes were included. Trials were excluded if supplements were not exclusive to vitamin C and if <2 weeks in duration. DATA EXTRACTION Primary outcomes were HbA1c, glucose, cholesterol, triglycerides, and blood pressure (BP). Data were extracted for changes in outcomes between vitamin C and control groups. Evidence certainty was assessed using Grading of Recommendations, Assessment, Development, and Evaluation methods. DATA SYNTHESIS Twenty-eight studies (N = 1,574 participants) were included in the review. Outcomes that changed to a statistically and clinically significant extent with vitamin C were systolic BP (mean difference -6.27 [95% CI -9.60, -2.96] mmHg; P = 0.0002), with moderate evidence certainty, and HbA1c (-0.54% [-0.90, -0.17]; P = 0.004) and diastolic BP (-3.77 [-6.13, -1.42] mmHg; P = 0.002) with very low evidence certainty. LIMITATIONS Studies were predominantly short term (<6 months) with a small number of participants (n < 100). CONCLUSIONS While evidence from short-term studies suggests that vitamin C supplementation may improve glycemic control and BP in people with type 2 diabetes, vitamin C supplementation cannot currently be recommended as a therapy until larger, long-term, and high-quality trials confirm these findings.
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Affiliation(s)
- Shaun A Mason
- School of Exercise and Nutrition Sciences, Deakin University, Melbourne, Victoria, Australia
| | - Michelle A Keske
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, Geelong, Victoria, Australia
| | - Glenn D Wadley
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, Geelong, Victoria, Australia
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Mason SA, Trewin AJ, Parker L, Wadley GD. Antioxidant supplements and endurance exercise: Current evidence and mechanistic insights. Redox Biol 2020; 35:101471. [PMID: 32127289 PMCID: PMC7284926 DOI: 10.1016/j.redox.2020.101471] [Citation(s) in RCA: 58] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Revised: 02/11/2020] [Accepted: 02/17/2020] [Indexed: 01/07/2023] Open
Abstract
Antioxidant supplements are commonly consumed by endurance athletes to minimize exercise-induced oxidative stress, with the intention of enhancing recovery and improving performance. There are numerous commercially available nutritional supplements that are targeted to athletes and health enthusiasts that allegedly possess antioxidant properties. However, most of these compounds are poorly investigated with respect to their in vivo redox activity and efficacy in humans. Therefore, this review will firstly provide a background to endurance exercise-related redox signalling and the subsequent adaptations in skeletal muscle and vascular function. The review will then discuss commonly available compounds with purported antioxidant effects for use by athletes. N-acetyl cysteine may be of benefit over the days prior to an endurance event; while chronic intake of combined 1000 mg vitamin C + vitamin E is not recommended during periods of heavy training associated with adaptations in skeletal muscle. Melatonin, vitamin E and α-lipoic acid appear effective at decreasing markers of exercise-induced oxidative stress. However, evidence on their effects on endurance performance are either lacking or not supportive. Catechins, anthocyanins, coenzyme Q10 and vitamin C may improve vascular function, however, evidence is either limited to specific sub-populations and/or does not translate to improved performance. Finally, additional research should clarify the potential benefits of curcumin in improving muscle recovery post intensive exercise; and the potential hampering effects of astaxanthin, selenium and vitamin A on skeletal muscle adaptations to endurance training. Overall, we highlight the lack of supportive evidence for most antioxidant compounds to recommend to athletes.
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Affiliation(s)
- Shaun A Mason
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, Geelong, Australia
| | - Adam J Trewin
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, Geelong, Australia
| | - Lewan Parker
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, Geelong, Australia
| | - Glenn D Wadley
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, Geelong, Australia.
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Mir BA, Mason SA, May AK, Russell AP, Foletta VC. Overexpression of NDRG2 in skeletal muscle does not ameliorate the effects of stress in vivo. Exp Physiol 2020; 105:1326-1338. [PMID: 32468595 DOI: 10.1113/ep088620] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2020] [Accepted: 05/26/2020] [Indexed: 11/08/2022]
Abstract
NEW FINDINGS What is the central question of this study? Do elevated levels of the stress-response protein NDRG2 protect against fasting and chronic disease in mouse skeletal muscle? What is the main finding and its importance? NDRG2 levels increased in the tibialis anterior muscle in response to fasting and the effects of motor neurone disease. No alleviation of the stress-related and proteasomal pathways, mitochondrial dysfunction or muscle mass loss was observed even with the addition of exogenous NDRG2 indicating that the increase in NDRG2 is a normal adaptive response. ABSTRACT Skeletal muscle mass loss and dysfunction can arise from stress, which leads to enhanced protein degradation and metabolic impairment. The expression of N-myc downstream-regulated gene 2 (NDRG2) is induced in response to different stressors and is protective against the effects of stress in some tissues and cell types. Here, we investigated the endogenous NDRG2 response to the stress of fasting and chronic disease in mice and whether exogenous NDRG2 overexpression through adeno-associated viral (AAV) treatment ameliorated the response of skeletal muscle to these conditions. Endogenous levels of NDRG2 increased in the tibialis anterior muscle in response to 24 h fasting and with the development of the motor neurone disease, amyotrophic lateral sclerosis, in SOD1G93A transgenic mice. Despite AAV-induced overexpression and increased expression with fasting, NDRG2 was unable to protect against the activation of proteasomal and stress pathways in response to fasting. Furthermore, NDRG2 was unable to reduce muscle mass loss, mitochondrial dysfunction and elevated oxidative and endoplasmic reticulum stress levels in SOD1G93A mice. Conversely, elevated NDRG2 levels did not exacerbate these stress responses. Overall, increasing NDRG2 levels might not be a useful therapeutic strategy to alleviate stress-related disease pathologies in skeletal muscle.
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Affiliation(s)
- Bilal A Mir
- Institute for Physical Activity and Nutrition (IPAN), School of Exercise and Nutrition Sciences, Deakin University, Geelong, Australia.,Institute of Muscle Biology & Growth, Leibniz Institute for Farm Animal Biology, Dummerstorf, Germany
| | - Shaun A Mason
- Institute for Physical Activity and Nutrition (IPAN), School of Exercise and Nutrition Sciences, Deakin University, Geelong, Australia
| | - Anthony K May
- Institute for Physical Activity and Nutrition (IPAN), School of Exercise and Nutrition Sciences, Deakin University, Geelong, Australia
| | - Aaron P Russell
- Institute for Physical Activity and Nutrition (IPAN), School of Exercise and Nutrition Sciences, Deakin University, Geelong, Australia
| | - Victoria C Foletta
- Institute for Physical Activity and Nutrition (IPAN), School of Exercise and Nutrition Sciences, Deakin University, Geelong, Australia
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Hamley S, Kloosterman D, Duthie T, Dalla Man C, Visentin R, Mason SA, Ang T, Selathurai A, Kaur G, Morales-Scholz MG, Howlett KF, Kowalski GM, Shaw CS, Bruce CR. Mechanisms of hyperinsulinaemia in apparently healthy non-obese young adults: role of insulin secretion, clearance and action and associations with plasma amino acids. Diabetologia 2019; 62:2310-2324. [PMID: 31489455 PMCID: PMC6861536 DOI: 10.1007/s00125-019-04990-y] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/04/2019] [Accepted: 07/29/2019] [Indexed: 01/07/2023]
Abstract
AIMS/HYPOTHESIS This study aimed to examine the metabolic health of young apparently healthy non-obese adults to better understand mechanisms of hyperinsulinaemia. METHODS Non-obese (BMI < 30 kg/m2) adults aged 18-35 years (N = 254) underwent a stable isotope-labelled OGTT. Insulin sensitivity, glucose effectiveness and beta cell function were determined using oral minimal models. Individuals were stratified into quartiles based on their insulin response during the OGTT, with quartile 1 having the lowest and quartile 4 the highest responses. RESULTS Thirteen per cent of individuals had impaired fasting glucose (IFG; n = 14) or impaired glucose tolerance (IGT; n = 19), allowing comparisons across the continuum of insulin responses within the spectrum of normoglycaemia and prediabetes. BMI (~24 kg/m2) was similar across insulin quartiles and in those with IFG and IGT. Despite similar glycaemic excursions, fasting insulin, triacylglycerols and cholesterol were elevated in quartile 4. Insulin sensitivity was lowest in quartile 4, and accompanied by increased insulin secretion and reduced insulin clearance. Individuals with IFG had similar insulin sensitivity and beta cell function to those in quartiles 2 and 3, but were more insulin sensitive than individuals in quartile 4. While individuals with IGT had a similar degree of insulin resistance to quartile 4, they exhibited a more severe defect in beta cell function. Plasma branched-chain amino acids were not elevated in quartile 4, IFG or IGT. CONCLUSIONS/INTERPRETATION Hyperinsulinaemia within normoglycaemic young, non-obese adults manifests due to increased insulin secretion and reduced insulin clearance. Individual phenotypic characterisation revealed that the most hyperinsulinaemic were more similar to individuals with IGT than IFG, suggesting that hyperinsulinaemic individuals may be on the continuum toward IGT. Furthermore, plasma branched-chain amino acids may not be an effective biomarker in identifying hyperinsulinaemia and insulin resistance in young non-obese adults.
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Affiliation(s)
- Steven Hamley
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, 221 Burwood Highway, Burwood, VIC, 3125, Australia
| | - Danielle Kloosterman
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, 221 Burwood Highway, Burwood, VIC, 3125, Australia
| | - Tamara Duthie
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, 221 Burwood Highway, Burwood, VIC, 3125, Australia
| | - Chiara Dalla Man
- Department of Information Engineering, University of Padova, Padova, Italy
| | - Roberto Visentin
- Department of Information Engineering, University of Padova, Padova, Italy
| | - Shaun A Mason
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, 221 Burwood Highway, Burwood, VIC, 3125, Australia
| | - Teddy Ang
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, 221 Burwood Highway, Burwood, VIC, 3125, Australia
| | - Ahrathy Selathurai
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, 221 Burwood Highway, Burwood, VIC, 3125, Australia
| | - Gunveen Kaur
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, 221 Burwood Highway, Burwood, VIC, 3125, Australia
| | - Maria G Morales-Scholz
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, 221 Burwood Highway, Burwood, VIC, 3125, Australia
| | - Kirsten F Howlett
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, 221 Burwood Highway, Burwood, VIC, 3125, Australia
| | - Greg M Kowalski
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, 221 Burwood Highway, Burwood, VIC, 3125, Australia
| | - Christopher S Shaw
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, 221 Burwood Highway, Burwood, VIC, 3125, Australia
| | - Clinton R Bruce
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, 221 Burwood Highway, Burwood, VIC, 3125, Australia.
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Mason SA, Rasmussen B, van Loon LJC, Salmon J, Wadley GD. Ascorbic acid supplementation improves postprandial glycaemic control and blood pressure in individuals with type 2 diabetes: Findings of a randomized cross-over trial. Diabetes Obes Metab 2019; 21:674-682. [PMID: 30394006 DOI: 10.1111/dom.13571] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/23/2018] [Revised: 10/23/2018] [Accepted: 10/31/2018] [Indexed: 12/14/2022]
Abstract
AIM The primary aim of this study was to investigate whether ascorbic acid (AA) supplementation improves postprandial glucose responses under free-living conditions in individuals with type 2 diabetes. A secondary aim was to investigate the effect of AA supplementation on blood pressure. MATERIALS AND METHODS A total of 31 individuals with type 2 diabetes (26 males and 5 females; aged 61.8 ± 6.8 years; duration of diabetes, 5.6 ± 4.6 years; HbA1c, 7.6% ± 0.7% [mean ± SD]) were enrolled in a randomized cross-over study involving 4 months of supplementation with oral AA (2 × 500 mg/d) or placebo. Participants wore continuous glucose monitors for 48 hours and consumed standardized meals pre- and post-supplementation. Measurements included postprandial glucose incremental areas under the curve (iAUC), duration of day in hyper- and hypo-glycaemia status, average 24-hour and daily postprandial glucose concentrations, HbA1c, insulin, blood pressure (BP) and oxidative stress (F2 -isoprostanes). RESULTS Following AA supplementation, significant decreases were observed in daily postprandial glucose iAUC (-36%), in duration of day with hyperglycaemia (-2.8 h/d) and postprandial hyperglycaemia (-1.7 h/d), in average 24-hour glucose (-0.8 mmol/L) and daily postprandial glucose (-1.1 mmol/L) concentrations, in systolic (-7 mm Hg) and diastolic (-5 mm Hg) blood pressures and in a specific fraction of free plasma F2 -isoprostanes (-47 pg/mL) as compared to placebo. CONCLUSIONS Individuals with type 2 diabetes experienced improved postprandial and 24-hour glycaemia and decreased BP after 4 months of AA supplementation as compared to placebo. These findings offer evidence for the proposed use of AA as an adjunct therapy to improve glycaemic and BP control in individuals with type 2 diabetes.
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Affiliation(s)
- Shaun A Mason
- School of Exercise and Nutrition Sciences, Institute for Physical Activity and Nutrition, Deakin University, Geelong, Victoria, Australia
| | - Bodil Rasmussen
- School of Nursing and Midwifery, Faculty of Health, Deakin University, Geelong, Victoria, Australia
- Western Health, Sunshine Hospital, St Albans, Victoria, Australia
| | - Luc J C van Loon
- Department of Human Biology, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre, Maastricht, The Netherlands
| | - Jo Salmon
- School of Exercise and Nutrition Sciences, Institute for Physical Activity and Nutrition, Deakin University, Geelong, Victoria, Australia
| | - Glenn D Wadley
- School of Exercise and Nutrition Sciences, Institute for Physical Activity and Nutrition, Deakin University, Geelong, Victoria, Australia
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McNeish RE, Kim LH, Barrett HA, Mason SA, Kelly JJ, Hoellein TJ. Microplastic in riverine fish is connected to species traits. Sci Rep 2018; 8:11639. [PMID: 30076314 PMCID: PMC6076259 DOI: 10.1038/s41598-018-29980-9] [Citation(s) in RCA: 125] [Impact Index Per Article: 20.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2017] [Accepted: 07/23/2018] [Indexed: 11/09/2022] Open
Abstract
Microplastic is a contaminant of concern worldwide. Rivers are implicated as major pathways of microplastic transport to marine and lake ecosystems, and microplastic ingestion by freshwater biota is a risk associated with microplastic contamination, but there is little research on microplastic ecology within freshwater ecosystems. Microplastic uptake by fish is likely affected by environmental microplastic abundance and aspects of fish ecology, but these relationships have rarely been addressed. We measured the abundance and composition of microplastic in fish and surface waters from 3 major tributaries of Lake Michigan, USA. Microplastic was detected in fish and surface waters from all 3 sites, but there was no correlation between microplastic concentrations in fish and surface waters. Rather, there was a significant effect of functional feeding group on microplastic concentration in fish. Neogobius melanostomus (round goby, a zoobenthivore) had the highest concentration of gut microplastic (19 particles fish-1) compared to 10 other fish taxa measured, and had a positive linear relationship between body size and number of microplastic particles. Surface water microplastic concentrations were lowest in the most northern, forested watershed, and highest in the most southern, agriculturally dominated watershed. Results suggest microplastic pollution is common in river food webs and is connected to species feeding characteristics. Future research should focus on understanding the movement of microplastic from point-source and diffuse sources and into aquatic ecosystems, which will support pollution management efforts on inland waters.
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Affiliation(s)
- R E McNeish
- Loyola University Chicago - Biology, 1032 West Sheridan Road, Chicago, IL, 60660, USA.
| | - L H Kim
- Loyola University Chicago - Biology, 1032 West Sheridan Road, Chicago, IL, 60660, USA
| | - H A Barrett
- Department of Geology and Environmental Sciences, The State University of New York at Fredonia, 280 Central Ave., Science Complex 340, Fredonia, NY, 14063, USA
| | - S A Mason
- Department of Geology and Environmental Sciences, The State University of New York at Fredonia, 280 Central Ave., Science Complex 340, Fredonia, NY, 14063, USA
| | - J J Kelly
- Loyola University Chicago - Biology, 1032 West Sheridan Road, Chicago, IL, 60660, USA
| | - T J Hoellein
- Loyola University Chicago - Biology, 1032 West Sheridan Road, Chicago, IL, 60660, USA
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Kowalski GM, Kraakman MJ, Mason SA, Murphy AJ, Bruce CR. Resolution of glucose intolerance in long-term high-fat, high-sucrose-fed mice. J Endocrinol 2017; 233:269-279. [PMID: 28360081 DOI: 10.1530/joe-17-0004] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/02/2017] [Accepted: 03/30/2017] [Indexed: 02/03/2023]
Abstract
The high-fat, high-sucrose diet (HFSD)-fed C57Bl/6 mouse is a widely used model of prediabetes. However, studies typically implement a relatively short dietary intervention lasting between 4 and 16 weeks; as a result, little is known about how a long-term HFSD influences the metabolic profile of these mice. Therefore, the aim of this investigation was to examine the effects of consuming a HFSD for 42 weeks on the development of hyperinsulinaemia and glucose intolerance in male C57Bl/6 mice. Two cohorts of HFSD mice were studied at independent institutes and they underwent an oral glucose tolerance test (OGTT) with measures of plasma insulin and free fatty acids (FFA). Age-matched chow-fed control mice were also studied. The HFSD-fed mice were hyperinsulinaemic and grossly obese, being over 25 g heavier than chow-fed mice, which was due to a marked expansion of subcutaneous adipose tissue. This was associated with a 3-fold increase in liver lipid content. Glucose tolerance, however, was either the same or better than control mice due to the preservation of glucose disposal as revealed by a dynamic stable isotope-labelled OGTT. In addition, plasma FFAs were suppressed to lower levels in HFSD mice during the OGTT. In conclusion, we have made the paradoxical observation that long-term HFSD feeding results in the resolution of glucose intolerance in the C57Bl/6 mouse. Mechanistically, we propose that the gross expansion of subcutaneous adipose tissue increases the glucose disposal capacity of the HFSD-fed mouse, which overcomes the prevailing insulin resistance to improve glucose tolerance.
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Affiliation(s)
- Greg M Kowalski
- Institute for Physical Activity and NutritionSchool of Exercise and Nutrition Sciences, Deakin University, Geelong, Victoria, Australia
| | - Michael J Kraakman
- Haematopoiesis and Leukocyte Biology LaboratoryBaker IDI Heart and Diabetes Institute, Melbourne, Victoria, Australia
- Department of MedicineColumbia University College of Physicians and Surgeons, New York, New York, USA
| | - Shaun A Mason
- Institute for Physical Activity and NutritionSchool of Exercise and Nutrition Sciences, Deakin University, Geelong, Victoria, Australia
| | - Andrew J Murphy
- Haematopoiesis and Leukocyte Biology LaboratoryBaker IDI Heart and Diabetes Institute, Melbourne, Victoria, Australia
| | - Clinton R Bruce
- Institute for Physical Activity and NutritionSchool of Exercise and Nutrition Sciences, Deakin University, Geelong, Victoria, Australia
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Mason SA, Morrison D, McConell GK, Wadley GD. Muscle redox signalling pathways in exercise. Role of antioxidants. Free Radic Biol Med 2016; 98:29-45. [PMID: 26912034 DOI: 10.1016/j.freeradbiomed.2016.02.022] [Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/01/2015] [Revised: 02/05/2016] [Accepted: 02/17/2016] [Indexed: 01/01/2023]
Abstract
Recent research highlights the importance of redox signalling pathway activation by contraction-induced reactive oxygen species (ROS) and nitric oxide (NO) in normal exercise-related cellular and molecular adaptations in skeletal muscle. In this review, we discuss some potentially important redox signalling pathways in skeletal muscle that are involved in acute and chronic responses to contraction and exercise. Specifically, we discuss redox signalling implicated in skeletal muscle contraction force, mitochondrial biogenesis and antioxidant enzyme induction, glucose uptake and muscle hypertrophy. Furthermore, we review evidence investigating the impact of major exogenous antioxidants on these acute and chronic responses to exercise. Redox signalling pathways involved in adaptive responses in skeletal muscle to exercise are not clearly elucidated at present, and further research is required to better define important signalling pathways involved. Evidence of beneficial or detrimental effects of specific antioxidant compounds on exercise adaptations in muscle is similarly limited, particularly in human subjects. Future research is required to not only investigate effects of specific antioxidant compounds on skeletal muscle exercise adaptations, but also to better establish mechanisms of action of specific antioxidants in vivo. Although we feel it remains somewhat premature to make clear recommendations in relation to application of specific antioxidant compounds in different exercise settings, a bulk of evidence suggests that N-acetylcysteine (NAC) is ergogenic through its effects on maintenance of muscle force production during sustained fatiguing events. Nevertheless, a current lack of evidence from studies using performance tests representative of athletic competition and a potential for adverse effects with high doses (>70mg/kg body mass) warrants caution in its use for performance enhancement. In addition, evidence implicates high dose vitamin C (1g/day) and E (≥260 IU/day) supplementation in impairments to some skeletal muscle cellular adaptations to chronic exercise training. Thus, determining the utility of antioxidant supplementation in athletes likely requires a consideration of training and competition periodization cycles of athletes in addition to type, dose and duration of antioxidant supplementation.
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Affiliation(s)
- Shaun A Mason
- Centre for Physical Activity and Nutrition (C-PAN) Research, School of Exercise and Nutrition Sciences, Deakin University, Geelong, Victoria, Australia
| | - Dale Morrison
- Centre for Physical Activity and Nutrition (C-PAN) Research, School of Exercise and Nutrition Sciences, Deakin University, Geelong, Victoria, Australia
| | - Glenn K McConell
- Clinical Exercise Science Research Program, Institute for Sport, Exercise and Active Living (ISEAL), Victoria University, Melbourne, Victoria, Australia
| | - Glenn D Wadley
- Centre for Physical Activity and Nutrition (C-PAN) Research, School of Exercise and Nutrition Sciences, Deakin University, Geelong, Victoria, Australia.
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Mason SA, Della Gatta PA, Snow RJ, Russell AP, Wadley GD. Ascorbic acid supplementation improves skeletal muscle oxidative stress and insulin sensitivity in people with type 2 diabetes: Findings of a randomized controlled study. Free Radic Biol Med 2016; 93:227-38. [PMID: 26774673 DOI: 10.1016/j.freeradbiomed.2016.01.006] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/29/2015] [Revised: 01/06/2016] [Accepted: 01/12/2016] [Indexed: 12/25/2022]
Abstract
AIM/HYPOTHESIS Skeletal muscle insulin resistance and oxidative stress are characteristic metabolic disturbances in people with type 2 diabetes. Studies in insulin resistant rodents show an improvement in skeletal muscle insulin sensitivity and oxidative stress following antioxidant supplementation. We therefore investigated the potential ameliorative effects of antioxidant ascorbic acid (AA) supplementation on skeletal muscle insulin sensitivity and oxidative stress in people with type 2 diabetes. METHODS Participants with stable glucose control commenced a randomized cross-over study involving four months of AA (2 × 500 mg/day) or placebo supplementation. Insulin sensitivity was assessed using a hyperinsulinaemic, euglycaemic clamp coupled with infusion of 6,6-D2 glucose. Muscle biopsies were measured for AA concentration and oxidative stress markers that included basal measures (2',7'-dichlorofluorescin [DCFH] oxidation, ratio of reduced-to-oxidized glutathione [GSH/GSSG] and F2-Isoprostanes) and insulin-stimulated measures (DCFH oxidation). Antioxidant concentrations, citrate synthase activity and protein abundances of sodium-dependent vitamin C transporter 2 (SVCT2), total Akt and phosphorylated Akt (ser473) were also measured in muscle samples. RESULTS AA supplementation significantly increased insulin-mediated glucose disposal (delta rate of glucose disappearance; ∆Rd) (p=0.009), peripheral insulin-sensitivity index (p=0.046), skeletal muscle AA concentration (p=0.017) and muscle SVCT2 protein expression (p=0.008); but significantly decreased skeletal muscle DCFH oxidation during hyperinsulinaemia (p=0.007) when compared with placebo. Total superoxide dismutase activity was also lower following AA supplementation when compared with placebo (p=0.006). Basal oxidative stress markers, citrate synthase activity, endogenous glucose production, HbA1C and muscle Akt expression were not significantly altered by AA supplementation. CONCLUSIONS/INTERPRETATION In summary, oral AA supplementation ameliorates skeletal muscle oxidative stress during hyperinsulinaemia and improves insulin-mediated glucose disposal in people with type 2 diabetes. Findings implicate AA supplementation as a potentially inexpensive, convenient, and effective adjunct therapy in the treatment of insulin resistance in people with type 2 diabetes.
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Affiliation(s)
- Shaun A Mason
- Centre for Physical Activity and Nutrition (C-PAN) Research, School of Exercise and Nutrition Sciences, Deakin University, 221 Burwood Highway, Burwood, Victoria 3125, Australia
| | - Paul A Della Gatta
- Centre for Physical Activity and Nutrition (C-PAN) Research, School of Exercise and Nutrition Sciences, Deakin University, 221 Burwood Highway, Burwood, Victoria 3125, Australia
| | - Rod J Snow
- Centre for Physical Activity and Nutrition (C-PAN) Research, School of Exercise and Nutrition Sciences, Deakin University, 221 Burwood Highway, Burwood, Victoria 3125, Australia
| | - Aaron P Russell
- Centre for Physical Activity and Nutrition (C-PAN) Research, School of Exercise and Nutrition Sciences, Deakin University, 221 Burwood Highway, Burwood, Victoria 3125, Australia
| | - Glenn D Wadley
- Centre for Physical Activity and Nutrition (C-PAN) Research, School of Exercise and Nutrition Sciences, Deakin University, 221 Burwood Highway, Burwood, Victoria 3125, Australia.
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Mason SA, Baptista R, Della Gatta PA, Yousif A, Russell AP, Wadley GD. High-dose vitamin C supplementation increases skeletal muscle vitamin C concentration and SVCT2 transporter expression but does not alter redox status in healthy males. Free Radic Biol Med 2014; 77:130-8. [PMID: 25242204 DOI: 10.1016/j.freeradbiomed.2014.09.013] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/14/2014] [Revised: 09/08/2014] [Accepted: 09/09/2014] [Indexed: 11/24/2022]
Abstract
Antioxidant vitamin C (VC) supplementation is of potential clinical benefit to individuals with skeletal muscle oxidative stress. However, there is a paucity of data reporting on the bioavailability of high-dose oral VC in human skeletal muscle. We aimed to establish the time course of accumulation of VC in skeletal muscle and plasma during high-dose VC supplementation in healthy individuals. Concurrently we investigated the effects of VC supplementation on expression levels of the key skeletal muscle VC transporter sodium-dependent vitamin C transporter 2 (SVCT2) and intramuscular redox and mitochondrial measures. Eight healthy males completed a randomized placebo-controlled, crossover trial involving supplementation with ascorbic acid (2×500 mg/day) over 42 days. Participants underwent muscle and blood sampling on days 0, 1, 7, and 42 during each treatment. VC supplementation significantly increased skeletal muscle VC concentration after 7 days, which was maintained at 42 days (VC 3.0±0.2 (mean±SEM) to 3.9±0.4 mg/100 g wet weight (ww) versus placebo 3.1±0.3 to 2.9±0.2 mg/100 g ww, p=0.001). Plasma VC increased after 1 day, which was maintained at 42 days (VC 61.0±6.1 to 111.5±10.4 µmol/L versus placebo 60.7±5.3 to 59.2±4.8 µmol/L, p<0.001). VC supplementation significantly increased skeletal muscle SVCT2 protein expression (main treatment effect p=0.006) but did not alter skeletal muscle redox measures or citrate synthase activity. A main finding of our study was that 7 days of high-dose VC supplementation was required to significantly increase skeletal muscle vitamin C concentration in healthy males. Our findings implicate regular high-dose vitamin C supplementation as a means to safely increase skeletal muscle vitamin C concentration without impairing intramuscular ascorbic acid transport, antioxidant concentrations, or citrate synthase activity.
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Affiliation(s)
- Shaun A Mason
- Centre for Physical Activity and Nutrition Research, School of Exercise and Nutrition Sciences, Deakin University, Burwood, VIC 3125, Australia
| | - Raquel Baptista
- Centre for Physical Activity and Nutrition Research, School of Exercise and Nutrition Sciences, Deakin University, Burwood, VIC 3125, Australia
| | - Paul A Della Gatta
- Centre for Physical Activity and Nutrition Research, School of Exercise and Nutrition Sciences, Deakin University, Burwood, VIC 3125, Australia
| | - Adel Yousif
- Centre for Physical Activity and Nutrition Research, School of Exercise and Nutrition Sciences, Deakin University, Burwood, VIC 3125, Australia
| | - Aaron P Russell
- Centre for Physical Activity and Nutrition Research, School of Exercise and Nutrition Sciences, Deakin University, Burwood, VIC 3125, Australia
| | - Glenn D Wadley
- Centre for Physical Activity and Nutrition Research, School of Exercise and Nutrition Sciences, Deakin University, Burwood, VIC 3125, Australia.
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Viero C, Euden J, Mason SA, Seidel MK, Thomas NL, Zissimopoulos S, Williams AJ. P373Two key regions of the human cardiac ryanodine receptor calcium release channel modulate its gating properties in a dual manner. Cardiovasc Res 2014. [DOI: 10.1093/cvr/cvu091.56] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Cuypers MG, Mason SA, Blakeley MP, Mitchell EP, Haertlein M, Forsyth VT. Near-atomic resolution neutron crystallography on perdeuterated Pyrococcus furiosus rubredoxin: implication of hydronium ions and protonation state equilibria in redox changes. Angew Chem Int Ed Engl 2012; 52:1022-5. [PMID: 23225503 DOI: 10.1002/anie.201207071] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2012] [Indexed: 11/09/2022]
Affiliation(s)
- M G Cuypers
- EPSAM/ISTM, Keele University, Staffordshire, ST5 5BG, UK
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17
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KilBride AL, Mason SA, Honeyman PC, Pritchard DG, Hepple S, Green LE. Associations between membership of farm assurance and organic certification schemes and compliance with animal welfare legislation. Vet Rec 2011; 170:152. [PMID: 22331783 DOI: 10.1136/vr.100345] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Animal health (AH) defines the outcome of their inspections of livestock holdings as full compliance with the legislation and welfare code (A), compliance with the legislation but not the code (B), non-compliance with legislation but no pain, distress or suffering obvious in the animals (C) or evidence of unnecessary pain or unnecessary distress (D). The aim of the present study was to investigate whether membership of farm assurance or organic certification schemes was associated with compliance with animal welfare legislation as inspected by AH. Participating schemes provided details of their members, past and present, and these records were matched against inspection data from AH. Multivariable multilevel logistic binomial models were built to investigate the association between compliance with legislation and membership of a farm assurance/organic scheme. The percentage of inspections coded A, B, C or D was 37.1, 35.6, 20.2 and 7.1 per cent, respectively. Once adjusted for year, country, enterprise, herd size and reason for inspection, there was a pattern of significantly reduced risk of codes C and D compared with A and B, in certified enterprises compared with the enterprises that were not known to be certified in all species.
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Affiliation(s)
- A L KilBride
- School of Life Sciences, University of Warwick, Coventry CV4 7AL, UK
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Kovalevsky AY, Hanson BL, Mason SA, Yoshida T, Fisher SZ, Mustyakimov M, Forsyth VT, Blakeley MP, Keen DA, Langan P. Identification of the elusive hydronium ion exchanging roles with a proton in an enzyme at lower pH values. Angew Chem Int Ed Engl 2011; 50:7520-3. [PMID: 21604345 DOI: 10.1002/anie.201101753] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2011] [Indexed: 11/08/2022]
Affiliation(s)
- Andrey Y Kovalevsky
- Bioscience Division, Los Alamos National Laboratory, Los Alamos, NM 87544, USA.
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Amory JR, Barker ZE, Wright JL, Mason SA, Blowey RW, Green LE. Associations between sole ulcer, white line disease and digital dermatitis and the milk yield of 1824 dairy cows on 30 dairy cow farms in England and Wales from February 2003-November 2004. Prev Vet Med 2008; 83:381-91. [PMID: 18031851 DOI: 10.1016/j.prevetmed.2007.09.007] [Citation(s) in RCA: 104] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2006] [Revised: 09/27/2007] [Accepted: 09/28/2007] [Indexed: 10/22/2022]
Abstract
The milk yields of 1824 cows were used to investigate the effect of lesion-specific causes of lameness, based on farmer treatment and diagnosis of lame cows, on milk yield. A three-level hierarchical model of repeated test day yields within cows within herds was used to investigate the impact of lesion-specific causes of lameness (sole ulcer, white line disease, digital dermatitis and other causes) on milk yield before and after treatment compared with unaffected cows. Cattle which developed sole ulcer (SU) and white line disease (WLD) were higher yielding cattle before they were diagnosed. Their milk production fell to below that of the mean of unaffected cows before diagnosis and remained low after diagnosis. In cattle which developed digital dermatitis (DD) there was no significant difference in milk yield before treatment and a slightly raised milk yield immediately after treatment. The estimated milk loss attributable to SU and WLD was approximately 570 and 370 kg, respectively. These results highlight that specific types of lameness vary by herds and within herds they are associated with higher yielding cattle. Consequently lesion-specific lameness reduction programmes targeting the cow and farm specific causes of lameness might be more effective than generic recommendations. They also highlight the importance of milk loss when estimating the economic impact of SU and WLD on the farms profitability.
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Affiliation(s)
- J R Amory
- Ecology and Epidemiology Group, Department of Biological Sciences, University of Warwick, UK.
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20
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Imamura K, Nimz O, Jacob J, Myles D, Mason SA, Kitamura S, Aree T, Saenger W. Hydrogen-bond network in cyclodecaamylose hydrate at 20 K; neutron diffraction study of novel structural motifs band-flip and kink in alpha-(1-->4)-D-glucoside oligosaccharides. Acta Crystallogr B 2001; 57:833-41. [PMID: 11717483 DOI: 10.1107/s0108768101014288] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2001] [Accepted: 08/30/2001] [Indexed: 11/10/2022]
Abstract
A single-crystal neutron diffraction study of cyclodecaamylose (CA10) was carried out at 20 K. CA10 crystallizes with 27.18 water molecules [(C(6)H(10)O(5))(10).27.18H(2)O] in space group C2 with unit-cell constants a = 29.31 (5), b = 9.976 (10), c = 19.34 (2) A, beta = 121.07 (2) degrees. The asymmetric unit contains a half molecule of CA10 and 13.59 water molecules, the other half being related by a crystallographic twofold rotation axis. All H atoms except two water H atoms could be located from difference neutron-density maps; structure refinement converged at R = 0.635. Two of the five CH(2)-O6 groups and one of the 15 O2, O3 hydroxyl groups of CA10 are twofold orientationally disordered. A total of 13.59 water molecules in the asymmetric unit are distributed over 23 positions; 20 of which are in the CA10 cavity, and the other three occupy intermolecular interstices. Of the 123 symmetry-independent hydrogen bonds, 25 (= 20%) are three-centered and 7 (= 6%) are four-centered. Water molecules and O-H groups of CA10 form an extended network with cooperative O-H...O-H...O-H hydrogen bonds. They are arranged in 11 polygons with three, four, five, six and eight O-H bonds and in homodromic, antidromic and heterodromic arrangements. Nine polygons are located within the cavity and the others are outside.
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Affiliation(s)
- K Imamura
- Institut für Kristallographie, Freie Universität Berlin, Takustrasse 6, D-14195 Berlin, Germany
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21
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Scherer W, Sirsch P, Grosche M, Spiegler M, Mason SA, Gardiner MG. Agostic deformations based on electron delocalization in the alkyllithium-complex [{2-(Me3Si)2CLiC5H4N }2Electronic supplementary information (ESI) available: experimental and theoretical details of multipole refinements and model systems. See http://www.rsc.org/suppdata/cc/b1/b105452j/. Chem Commun (Camb) 2001:2072-3. [PMID: 12269281 DOI: 10.1039/b105452j] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Topological analysis of experimental and theoretical charge densities in the title complex [(2-(Me3Si)2CLiC5H4N)2] 1 reveals the nature of the agostic deformation postulated for this complex: delocalization of the Li-C bonding electrons over the entire agostic alkyl group controls the formation of an acute Li-C-Si angle and thus a sufficient electronic saturation of the electron deficient lithium atom via secondary interactions.
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Affiliation(s)
- W Scherer
- Anorganisch-chemisches Institut der Technischen Universität München, Lichtenbergstrasse 4, D-85747 Garching bei München, Germany.
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Ahrens B, Davidson MG, Forsyth VT, Mahon MF, Johnson AL, Mason SA, Price RD, Raithby PR. Neutron diffraction study of a phenol.nitroxide radical adduct: a structural model for hydrogen atom abstraction by peroxyl radicals from vitamin E and related phenolic antioxidants. J Am Chem Soc 2001; 123:9164-5. [PMID: 11552826 DOI: 10.1021/ja015849+] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
Affiliation(s)
- B Ahrens
- Department of Chemistry, University of Bath, Claverton Down, Bath BA2 7AY, UK
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Palmer RA, Potter BS, Lisgarten JN, Fenn RH, Mason SA, Mills OS, Robinson PM, Watt CI. X-ray and neutron structure of 1,8-(3,6,9-trioxaundecane-1,11-diyldioxy)-9,10-dihydro-10,10-dimethylanthracene-9-ol (P326); some pitfalls of automatic data collection. Acta Crystallogr B 2001; 57:339-45. [PMID: 11373392 DOI: 10.1107/s0108768100015184] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2000] [Accepted: 10/24/2000] [Indexed: 11/10/2022]
Abstract
The structure of the crown ether 1,8-(3,6,9-trioxaundecane-1,11-diyldioxy)-9,10-dihydro-10,10-dimethylanthracene-9-ol, C(24)H(30)O(6).H(2)O (1), code name P326, the parent compound for a series of derivatives, has been determined by both X-ray diffraction at room temperature and neutron diffraction at very low temperature. The unit cells are very similar at both temperatures and in both cases the crystals exhibit P2(1) symmetry with Z = 4 (two molecules, A and B, respectively, per asymmetric unit) and pseudosymmetry P2(1)/c. The higher symmetry is broken mainly by the two independent water molecules in the unit cell, some reflections which would be absent in P2(1)/c having strong intensities in both the X-ray and neutron data. In both molecules A and B hydrogen bonds involving the water molecule stabilize the macrocyclic ring structure, one involving the macrocyclic O(9) as a donor. Close contacts between the water and macrocyclic O atoms in each molecule also suggest the presence of two bifurcated hydrogen bonds, involving water HW2 to both O(16) and O(18), and water HW1 to both O(18) and O(20), respectively, with considerable variation in the geometry being present. Both molecules A and B exhibit very close pseudosymmetry across a plane perpendicular to the molecular plane and through atoms C(9) and O(18), and in addition are predominantly planar structures. The X-ray analysis failed to reveal one H atom per water molecule, each being subsequently included after location and refinement in the neutron analysis.
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Affiliation(s)
- R A Palmer
- Department of Crystallography, Birkbeck College, London WC1E 7HX, England.
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Fryzuk MD, Johnson SA, Patrick BO, Albinati A, Mason SA, Koetzle TF. New mode of coordination for the dinitrogen ligand: formation, bonding, and reactivity of a tantalum complex with a bridging N(2) unit that is both side-on and end-on. J Am Chem Soc 2001; 123:3960-73. [PMID: 11457146 DOI: 10.1021/ja0041371] [Citation(s) in RCA: 167] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The reaction of a mixture of 1 equiv of PhPH(2) and 2 equiv of PhNHSiMe(2)CH(2)Cl with 4 equiv of Bu(n)Li followed by the addition of THF generates the lithiated ligand precursor [NPN]Li(2).(THF)(2) (where [NPN] = PhP(CH(2)SiMe(2)NPh)(2)). The reaction of [NPN]Li(2).(THF)(2) with TaMe(3)Cl(2) produces [NPN]TaMe(3), which reacts under H(2) to yield the diamagnetic dinuclear Ta(IV) tetrahydride ([NPN]Ta)(2)(mu-H)(4). This hydride reacts with N(2) with the loss of H(2) to produce ([NPN]Ta(mu-H))(2)(mu-eta(1):eta(2)-N(2)), which was characterized both in solution and in the solid state, and contains strongly activated N(2) bound in the unprecedented side-on end-on dinuclear bonding mode. A density functional theory calculation on the model complex [(H(3)P)(H(2)N)(2)Ta(mu-H)](2)(mu-eta(1):eta(2)-N(2)) provides insight into the molecular orbital interactions involved in the side-on end-on bonding mode of dinitrogen. The reaction of ([NPN]Ta(mu-H))(2)(mu-eta(1):eta(2)-N(2)) with propene generates the end-on bound dinitrogen complex ([NPN]Ta(CH(2)CH(2)CH(3)))(2)(mu-eta(1):eta(1)-N(2)), and the reaction of [NPN]Li(2).(THF)(2) with NbCl(3)(DME) generates the end-on bound dinitrogen complex ([NPN]NbCl)(2)(mu-eta(1):eta(1)-N(2)). These two end-on bound dinitrogen complexes provide evidence that the bridging hydride ligands are responsible for the unusual bonding mode of dinitrogen in ([NPN]Ta(mu-H))(2)(mu-eta(1):eta(2)-N(2)). The dinitrogen moiety in the side-on end-on mode is amenable to functionalization; the reaction of ([NPN]Ta(mu-H))(2)(mu-eta(1):eta(2)-N(2)) with PhCH(2)Br results in C-N bond formation to yield [NPN]Ta(mu-eta(1):eta(2)-N(2)CH(2)Ph)(mu-H)(2)TaBr[NPN]. Nitrogen-15 NMR spectral data are provided for all the tantalum-dinitrogen complexes and derivatives described.
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Affiliation(s)
- M D Fryzuk
- Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, B.C., Canada
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Evdokimov A, Gilboa AJ, Koetzle TF, Klooster WT, Schultz AJ, Mason SA, Albinati A, Frolow F. Structures of furanosides: geometrical analysis of low-temperature X-ray and neutron crystal structures of five crystalline methyl pentofuranosides. Acta Crystallogr B 2001; 57:213-20. [PMID: 11262436 DOI: 10.1107/s010876810001661x] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2000] [Accepted: 11/08/2000] [Indexed: 11/10/2022]
Abstract
Crystal structures of all five crystalline methyl D-pentofuranosides, methyl alpha-D-arabinofuranoside (1), methyl beta-D-arabinofuranoside (2), methyl alpha-D-lyxofuranoside (3), methyl beta-D-ribofuranoside (4) and methyl alpha-D-xylofuranoside (5) have been determined by means of cryogenic X-ray and neutron crystallography. The neutron diffraction experiments provide accurate, unbiased H-atom positions which are especially important because of the critical role of hydrogen bonding in these systems. This paper summarizes the geometrical and conformational parameters of the structures of all five crystalline methyl pentofuranosides, several of them reported here for the first time. The methyl pentofuranoside structures are compared with the structures of the five crystalline methyl hexopyranosides for which accurate X-ray and neutron structures have been determined. Unlike the methyl hexopyranosides, which crystallize exclusively in the C(1) chair conformation, the five crystalline methyl pentofuranosides represent a very wide range of ring conformations.
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Affiliation(s)
- A Evdokimov
- Protein Engineering Section, Program in Structural Biology, NCI-Frederick Cancer Research and Development Center, PO Box B, Frederick, MD 21702, USA.
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Abstract
BACKGROUND Questions have been asked about whether the process of obtaining informed consent from parents to clinical trials on neonates leads to valid consent. We undertook a study in nine European countries to assess this issue and to seek any practical improvements. METHODS Semi-structured interviews were conducted with parents of 200 babies who had been asked for consent to neonatal trials and 107 neonatologists seeking consent. Analysis assessed the validity of the consent process against four components: parental competence; information given; parental understanding; and voluntariness of consent. FINDINGS 59 of the 200 parents had given valid consent or refusal but the remainder had problems in one or more of the component areas (42 for competence, 43 for information, 44 for understanding, and 21 for voluntariness). The proportions with impaired consent were greatest for research in an emergency situation and for that associated with risk or discomfort greater than standard treatment. Information sheets were little used by parents in deciding whether to consent. Parents highly valued their involvement in the informed consent process, and clinicians generally agreed on the value of the process. INTERPRETATION Current standards of informed consent to neonatal research projects could be improved. Research personnel should receive guidance on legal and ethical constraints governing the process. Oral and written information should be given at the same time. Parents could be made aware that research projects have been examined by research ethics committees. Little support was found for the argument that informed consent should be relinquished for the parents' own good. Further study is needed to identify which elements of the process are valued by parents and clinicians in a process that has some unavoidable limitations.
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Affiliation(s)
- S A Mason
- Northern and Yorkshire Clinical Trials and Research Unit, Leeds, UK.
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Mason SA. Performance-based planning for hospitals. Health Care Strateg Manage 2000; 18:14-7, 1. [PMID: 11125937] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/18/2023]
Abstract
It is time for health care planning to evolve through a new phase--from strategic planning to performance-based planning, writes Scott A. Mason, D.P.A., FACHE, president and CEO of eko systems inc.
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Dawson S, Hickey RG, Mason SA. Grassroots decisionmaking informs care redesign at York Hospital in York, PA. Strateg Healthc Excell 2000; 13:8-11. [PMID: 11009698] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/17/2023]
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Schneider JJ, Hagen J, Czap N, Kruger C, Mason SA, Bau R, Ensling J, Gutlich P, Wrackmeyer B. Hydroxo hydrido complexes of iron and cobalt (Sn-Fe-Sn, Sn-Co-Sn): probing agostic Sn...H-M interactions in solution and in the solid state. Chemistry 2000; 6:625-35. [PMID: 10807174 DOI: 10.1002/(sici)1521-3765(20000218)6:4<625::aid-chem625>3.0.co;2-i] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Bis(toluene)iron 9 reacts with Lappert's stannylene [Sn[CH(SiMe3)2]2] (4) to form the paramagnetic bis-stannylene complex [[(eta6-toluene)Fe-Sn-[CH(SiMe3)2]2]2] (10). Compound 10 reacts with H2O to form the hydroxo hydrido complex [(eta6-C7H8)(mu-OH)(H)-Fe-[Sn[CH(SiMe3)2]2]2] (12) in high yield; its solid-state structure has been elucidated by X-ray and neutron diffraction analysis. In agreement with the 1H NMR results, 12 contains a hydridic ligand whose exact coordination geometry could be determined by neutron diffraction. The 1H and 119Sn NMR analysis of 12 suggested a multicenter Sn/Sn/H/Fe bonding interaction in solution, based on significantly large values of J(Sn,H,Fe) = 640+/-30 Hz and J(119Sn,119Sn) = 4340+/-100 Hz. In solution, complex 12 exists as two diastereomers in a ratio of about 2:1. Neutron diffraction analysis has characterized 12 as a classical metal hydride complex with very little Sn...H interaction and a typical Fe-H single bond (1.575(8) A). This conclusion is based on the fact that the values of the Sn...H contact distances (2.482(9) and 2.499(9) A) are not consistent with strong Fe-H...Sn interactions. This finding is discussed in relation to other compounds containing M-H...Sn units with and without strong three-center interactions. The neutron diffraction analysis of 12 represents the first determination of a Sn-H atomic distance employing this analytical technique. The cobalt analogues [(eta5-Cp)(mu-OH)(H)Co-[Sn[CH(SiMe3)2]2]2] (15) and [(eta5-Cp)(OD)(D)Co-[Sn[CH-(SiMe3)2]2]2] [D2]15, which are isolobal with 12, were prepared by the reaction of [(eta5-Cp)Co-Sn[CH(SiMe3)2]2] (14) with H2O and D2O, respectively. The magnitude of J(Sn,H) (539 Hz) in 15 is in the same range as that found for 12. The molecular structure of 15 has been determined by X-ray diffraction which reveals it to be isostructural with 12. The coordination geometries of the Co(Fe)-Sn1-O-Sn2 arrangements in 12 and 15 are fully planar within experimental error. Compounds 10 and 15 are rare examples of fully characterized complexes obtained as primary products from water activation reactions.
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Affiliation(s)
- JJ Schneider
- Institut fur Anorganische Chemie der Universitat, Essen, Germany.
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Cade A, Brownlee KG, Conway SP, Haigh D, Short A, Brown J, Dassu D, Mason SA, Phillips A, Eglin R, Graham M, Chetcuti A, Chatrath M, Hudson N, Thomas A, Chetcuti PA. Randomised placebo controlled trial of nebulised corticosteroids in acute respiratory syncytial viral bronchiolitis. Arch Dis Child 2000; 82:126-30. [PMID: 10648365 PMCID: PMC1718208 DOI: 10.1136/adc.82.2.126] [Citation(s) in RCA: 95] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
OBJECTIVE To evaluate short and long term effects of giving nebulised budesonide early in respiratory syncytial viral (RSV) bronchiolitis. DESIGN A multicentre randomised double blind placebo controlled trial. SUBJECTS Infants admitted to hospital with their first episode of RSV positive bronchiolitis. INTERVENTION Randomisation to receive either 1 mg of nebulised budesonide (Bud) or placebo (Pla) twice daily from admission until 2 weeks after discharge. Follow up was for 12 months. MAIN OUTCOME MEASURES Duration of hospital admission, time taken to become symptom free, re-admission rates, general practitioner consultation rates, and use of anti-wheeze medication during follow up. RESULTS 161 infants were studied. Both arms were similar with respect to initial clinical severity, age, sex, socioeconomic class, and tobacco exposure. Median time from first nebulisation to discharge: Bud and Pla, 2 days. Median number of days for 50% of infants to be symptom free for 48 hours: Bud, 10 days; Pla, 12 days. Respiratory re-admission rates in the 12 month follow up: Bud, 16%; Pla, 18%; median difference (95% confidence interval (CI)), -2 (-14 to 10). Median respiratory related general practitioner attendances: Bud, 4.0; Pla, 4.5; median difference (95% CI), -1 (-2 to 0). Percentage of infants receiving at least one prescription for anti-wheeze medication during follow up, corticosteroids: Bud, 50%; Pla, 60%; difference (95% CI), -10 (-26 to 6); bronchodilators: Bud, 60%; Pla, 67%; difference (95% CI), -7 (-22 to 8). CONCLUSIONS There are no short or long term clinical benefits from the administration of nebulised corticosteroids in the acute phase of RSV bronchiolitis.
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Affiliation(s)
- A Cade
- Department of Paediatrics and Child Health, Clarendon Wing, Leeds General Infirmary, Belmont Grove, Leeds LS2 9NS, UK
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Mason SA. Service reconfiguration: preparing for clinical integration. Healthc Exec 1998; 13:12-6. [PMID: 10181095] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
Affiliation(s)
- S A Mason
- APACHE Medical Systems, McLean, VA, USA
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Mason SA, Hopkins M, McGowan RA, Brown M. Virtual roundtable: the do's and don'ts of negotiating a merger. Health Syst Lead 1996; 3:14-7. [PMID: 10159067] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
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Forsyth VT, Langan P, Whalley MA, Mahendrasingam A, Wilson CC, Giesen U, Dauvergne MT, Mason SA, Fuller W. Time-of-flight Laue fiber diffraction studies of perdeuterated DNA. Basic Life Sci 1996; 64:359-67. [PMID: 9031520 DOI: 10.1007/978-1-4615-5847-7_31] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The diffractometer SXD at the Rutherford Appleton Laboratory ISIS pulsed neutron source has been used to record high resolution time-of-flight Laue fiber diffraction data from DNA. These experiments, which are the first of their kind, were undertaken using fibers of DNA in the A conformation and prepared using deuterated DNA in order to minimise incoherent background scattering. These studies complement previous experiments on instrument D19 at the Institut Laue Langevin using monochromatic neutrons. Sample preparation involved drawing large numbers of these deuterated DNA fibers and mounting them in a parallel array. The strategy of data collection is discussed in terms of camera design, sample environment and data collection. The methods used to correct the recorded time-of-flight data and map it into the final reciprocal space fiber diffraction dataset are also discussed. Difference Fourier maps showing the distribution of water around A-DNA calculated on the basis of these data are compared with results obtained using data recorded from hydrogenated A-DNA on D19. Since the methods used for sample preparation, data collection and data processing are fundamentally different for the monochromatic and Laue techniques, the results of these experiments also afford a valuable opportunity to independently test the data reduction and analysis techniques used in the two methods.
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Affiliation(s)
- V T Forsyth
- Department of Physics, Keele University, Staffordshire, United Kingdom
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Fuller W, Forsyth VT, Mahendrasingam A, Langan P, Pigram WJ, Mason SA, Wilson CC. DNA hydration studied by neutron fiber diffraction. Basic Life Sci 1996; 64:345-58. [PMID: 9031519 DOI: 10.1007/978-1-4615-5847-7_30] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The development of neutron high angle fiber diffraction to investigate the location of water around the deoxyribonucleic acid (DNA) double-helix is described. The power of the technique is illustrated by its application to the D and A conformations of DNA using the single crystal diffractometer, D19, at the Institut Laue-Langevin. Grenoble and the time of flight diffractometer, SXD, at the Rutherford Appleton ISIS Spallation Neutron Source. These studies show the existence of bound water closely associated with the DNA. The patterns of hydration in these two DNA conformations are quite distinct and are compared to those observed in X-ray single crystal studies of two-stranded oligodeoxynucleotides. Information on the location of water around the DNA double-helix from the neutron fiber diffraction studies is combined with that on the location of alkali metal cations from complementary X-ray high angle fiber diffraction studies at the Daresbury Laboratory SRS using synchrotron radiation. These analyses emphasize the importance of viewing DNA, water and ions as a single system with specific interactions between the three components and provide a basis for understanding the effect of changes in the concentration of water and ions in inducing conformational transitions in the DNA double-helix.
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Affiliation(s)
- W Fuller
- Department of Physics, Keele University, Staffordshire, United Kingdom
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Mason SA. Consultants must keep act clean. Mod Healthc 1995; 25:28. [PMID: 10151399] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
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Mason SA, Seymour DW, Roach WH. The joint operating company: operational and legal considerations. Health Care Strateg Manage 1995; 13:6-8. [PMID: 10144167] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
Affiliation(s)
- S A Mason
- National Health Advisors, McLean, VA, USA
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Mason SA, Seymour DW. The joint operating company: an innovative approach to collaboration. Health Care Strateg Manage 1995; 13:11-3. [PMID: 10143018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
Abstract
Hospitals interested in horizontal integration often run into difficulties. In spite of otherwise sound business logic for two organizations to merge, there may be political, legal or financial reasons why a merger option cannot be pursued. Increasingly, enterprises are turning to a joint operating company structure as the solution to their needs. Scott A. Mason and Donald W. Seymour, partners with consulting firm National Health Advisors, explore situations where a JOC model of collaboration may be appropriate.
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Affiliation(s)
- S A Mason
- National Health Advisors, McLean, VA, USA
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Mason SA. Competition is not a four-letter word. Hosp Health Netw 1994; 68:60. [PMID: 8269013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- S A Mason
- National Health Advisors, McLean, VA
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Mason SA, Schumacher EJ, Seymour DW. Assessing models for integration: a strategic analysis. Health Syst Lead 1994; Suppl:8-18. [PMID: 10140093] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Mason SA. Young, scarred children and their mothers--a short-term investigation into the practical, psychological and social implications of thermal injury to the preschool child. Part I: Implications for the mother. Burns 1993; 19:495-500. [PMID: 8292233 DOI: 10.1016/0305-4179(93)90006-t] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
A short-term, prospective study, using both quantitative and qualitative methods, was designed to determine the practical, psychological and social implications of thermal injury resulting in scarring, for the mothers of thermally injured children, during the 6 months following the child's discharge from hospital. Mothers of 57 thermally injured children under 5 years of age were interviewed whilst the child was in hospital and at home, at 1 week, 2 months and 6 months following hospital discharge. Thermal injuries ranged from 1 to 41 per cent of body surface area and all required skin grafting. Qualitative analysis of interview transcripts resulted in the development of a model of the mother's response--The Maternal Thermal Injury Response Pattern (MTIRP)--which describes a phasic pattern of general response categories. The mothers' psychiatric morbidity was measured using Goldberg's (1978) 60-item General Health Questionnaire (GHQ). The mean of the mothers' total GHQ scores was 2.42 for the retrospective, pre-injury score, 24.5 at the hospital interview and 5.96 at 6 months following the child's discharge from hospital. In conclusion, the mother is a neglected victim of a young child's thermal injury. Use of the MTIRP as an educational tool for carers would promote increased understanding and, thus, more appropriate support.
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Affiliation(s)
- S A Mason
- Booth Hall Children's Hospital, Manchester, UK
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Mason SA, Housley PR. Site-directed mutagenesis of the phosphorylation sites in the mouse glucocorticoid receptor. J Biol Chem 1993; 268:21501-4. [PMID: 8407999] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
The functional significance of receptor phosphorylation in mediating the actions of glucocorticoids remains undefined. The identification of seven phosphorylation sites in the mouse glucocorticoid receptor (Bodwell, J. E., Orti, E., Coull, J. M., Pappin, D. J. C., Smith, L. I., and Swift, F. (1991) J. Biol. Chem. 266, 7549-7555) permits a direct examination of the potential regulatory role of glucocorticoid receptor phosphorylation in transactivation. Using oligonucleotide-directed mutagenesis of the mouse glucocorticoid receptor cDNA, we have substituted alanine or aspartate for the residues phosphorylated in this ligand-dependent transcription factor. COS-1 cells were cotransfected with mutant receptor cDNA expression vectors and a reporter plasmid containing the glucocorticoid-inducible mouse mammary tumor virus promoter linked to chloramphenicol acetyltransferase in order to characterize the effect of these substitutions on receptor-mediated gene expression. Substitution of alanine or aspartate at single phosphorylation sites does not prevent receptor transactivation. Receptors containing multiple substitutions of alanine or aspartate at the major phosphorylation sites in the acidic domain elicit levels of hormone-induced reporter gene expression that are comparable to wild-type receptors. Mutant receptors substituted with alanine at the five phosphorylation sites conserved among the rat, human, and mouse receptors exhibit a 22% decrease in transcriptional activity. Receptors mutated at all seven sites display a similar modest reduction. These results demonstrate that receptor phosphorylation at these seven identified residues is not a major determinant in glucocorticoid receptor transcriptional activity at the mouse mammary tumor virus promoter.
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Affiliation(s)
- S A Mason
- Department of Pharmacology, School of Medicine, University of South Carolina, Columbia 29208
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Abstract
There is an apparent lack of epistemological rigour when quantitative and qualitative methods are combined in the same study, because they reflect opposing positivist and interpretive perspectives. When and how to use methodological pluralism is discussed in this article.
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Langan P, Forsyth VT, Mahendrasingam A, Pigram WJ, Mason SA, Fuller W. A high angle neutron fibre diffraction study of the hydration of the A conformation of the DNA double helix. J Biomol Struct Dyn 1992; 10:489-503. [PMID: 1492921 DOI: 10.1080/07391102.1992.10508664] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
A high angle neutron fibre diffraction study of the distribution of water around the A-form of DNA has been performed using the diffractometer D19 at the Institut Laue-Langevin, Grenoble. These experiments have exploited the ability to replace H2O surrounding the DNA by D2O so that isotopic difference Fourier maps can be computed in which peaks are identified with the distribution of water in the unit cell. All peaks of significant height have been accounted for by four families of water molecules whose positions and occupancies have been determined using least squares refinement. The coordinates of the water peaks making up each family do not deviate significantly from a regular helical arrangement with the same parameters as the DNA. Two of these families are of particular interest. The first consists of water molecules in the major groove linking successive charged phosphate oxygens along the polynucleotide chains. The second is associated with bases in the major groove and forms a central core of density along the helix axis. These two families provide a layer of hydration lining the interior wall of the major groove leaving a central channel to accommodate cations. The relationship between these observations and conformational stability is discussed.
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Affiliation(s)
- P Langan
- Department of Physics, Keele University, Staffordshire
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Fletcher CA, Mason SA. Aerosol bronchodilator administration distally in a tracheal tube. Anaesthesia 1992; 47:84-5. [PMID: 1536434 DOI: 10.1111/j.1365-2044.1992.tb01994.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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Mason SA. Network integration. A new vision for Catholic healthcare systems in the 1990s. Health Prog 1990; 71:32-4, 46-7. [PMID: 10108005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
Abstract
The 1990s will be the decade of network integration for many of the nation's healthcare organizations. Catholic healthcare systems will have to refocus on local and regional healthcare delivery. To succeed in local and regional markets, the systems will have to offer various levels of care through numerous types of providers, share services among facilities, cooperate with secular organizations, and build stronger affiliations with local parishes. Managing this change (from offering fragmented healthcare services to offering integrated services) will be a major challenge facing organizations in the decade ahead. They must develop a clearly articulated vision to provide stability during this time of rapid change. To meet the challenges of the 1990s, Catholic healthcare systems will have to determine the types of functional sharing that will be beneficial at the local level, divest and transfer sponsorship of facilities that burden the system's mission, and expand the activities of the laity.
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Abstract
Three individuals who exhibited self-injurious behavior (SIB) were exposed to sensory-integrative therapy. Prior to treatment, a functional analysis baseline was conducted to identify the motivational features of their SIB. One subject's SIB appeared to be an attention-getting response (maintained by positive reinforcement), which varied subsequently as a function of attention being either withheld or provided noncontingently during sensory-integration sessions. The 2nd subject displayed a pattern of responding suggestive of stereotypic SIB (maintained by automatic reinforcement), which paradoxically increased during sensory-integration sessions. The 3rd subject's SIB appeared to function as an escape response (maintained by negative reinforcement), and his behavior during sensory-integration sessions was similar to that observed during baseline sessions in which demands were not present. The SIB of all 3 subjects later was reduced when behavior interventions were applied. The data presented raise questions about the active components of sensory-integrative therapy and the functional types of SIB for which it might be appropriate.
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Affiliation(s)
- S A Mason
- Department of Special Education, University of Maryland, College Park 20742
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Abstract
Interactions with water are crucial to the conformation assumed by the DNA double helix. The location of water around the D conformation has been investigated in a neutron fibre diffraction study which shows that water is ordered in the minor groove of the DNA. The D conformation is important since its occurrence is limited to specific DNA base pair sequences which have been identified as functionally significant. This study is of particular interest because the D conformation has not been reported in single crystal studies of oligonucleotides.
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Affiliation(s)
- V T Forsyth
- Department of Physics, University of Keele, Staffordshire, UK
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Abstract
There is a need for practical methods of reinforcer assessment that systematically track ongoing changes in clients' preferences. In this study, the effects of a time-efficient reinforcer assessment package were evaluated in a multiple baseline across 3 preschoolers with autism, comparing individualized item selections by experienced teachers with children's presession preferences for items of various sensory qualities. Systematic assessment of children's reinforcers for correct responding virtually eliminated nontargeted maladaptive behaviors, as well as yielding expected improvements in accuracy. The powerful side-effects of potent reinforcers underline the importance of increased attention to reinforcer assessment in research and practice.
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Affiliation(s)
- S A Mason
- Department of Psychology, University of Massachusetts, Amherst 01003
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