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McDonald MD, Brickley B, Pavey T, Smith JA, Maiorana A, McCaffrey T, Hillis G, Bonson J, Chih HJ, Gupta H, Holmes S, Hunt K, Kerr DA, Kwaśnicka D, Makate M, McVeigh J, Moullin JC, Smith BJ, Wharton L, Wharton N, Quested E. Scale-up of the Australian Fans in Training (Aussie-FIT) men's health behaviour change program: a protocol for a randomised controlled hybrid effectiveness-implementation trial. BMJ Open 2023; 13:e078302. [PMID: 37879681 PMCID: PMC10603488 DOI: 10.1136/bmjopen-2023-078302] [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: 07/29/2023] [Accepted: 09/23/2023] [Indexed: 10/27/2023] Open
Abstract
INTRODUCTION Improving physical activity (PA) and healthy eating is critical for primary and secondary prevention of cardiovascular disease (CVD). Behaviour change programmes delivered in sporting clubs can engage men in health behaviour change, but are rarely sustained or scaled-up post trial. Following the success of pilot studies of the Australian Fans in Training (Aussie-FIT) programme, a hybrid effectiveness-implementation trial protocol was developed. This protocol outlines methods to: (1) establish if Aussie-FIT is effective at supporting men with or at risk of CVD to sustain improvements in moderate-to-vigorous PA (primary outcome), diet and physical and psychological health and (2) examine the feasibility and utility of implementation strategies to support programme adoption, implementation and sustainment. METHODS AND ANALYSIS A pragmatic multistate/territory hybrid type 2 effectiveness-implementation parallel group randomised controlled trial with a 6-month wait list control arm in Australia. 320 men aged 35-75 years with or at risk of CVD will be recruited. Aussie-FIT involves 12 weekly face-to-face sessions including coach-led interactive education workshops and PA delivered in Australian Football League (Western Australia, Northern Territory) and rugby (Queensland) sports club settings. Follow-up measures will be at 3 and 6 months (both groups) and at 12 months to assess maintenance (intervention group only). Implementation outcomes will be reported using the Reach, Effectiveness, Adoption, Implementation, Maintenance framework. ETHICS AND DISSEMINATION This multisite study has been approved by the lead ethics committees in the lead site's jurisdiction, the South Metropolitan Health Service Human Research Ethics Committee (Reference RGS4254) and the West Australian Aboriginal Health Ethics Committee (HREC1221). Findings will be disseminated at academic conferences, peer-reviewed journals and via presentations and reports to stakeholders, including consumers. Findings will inform a blueprint to support the sustainment and scale-up of Aussie-FIT across diverse Australian settings and populations to benefit men's health. TRIAL REGISTRATION NUMBER This trial is registered with the Australian New Zealand Clinical Trials Registry (ACTRN12623000437662).
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Affiliation(s)
- Matthew David McDonald
- Physical Activity and Well-being Research Group, Enable Institute, Curtin University, Perth, Western Australia, Australia
- Curtin School of Population Health, Curtin University, Perth, Western Australia, Australia
| | - Bryce Brickley
- College of Medicine and Public Health, Rural and Remote Health, Flinders University, Darwin, Northern Territory, Australia
| | - Toby Pavey
- Exercise and Nutrition Sciences, Queensland University of Technology, Brisbane, Queensland, Australia
| | - James A Smith
- College of Medicine and Public Health, Rural and Remote Health, Flinders University, Darwin, Northern Territory, Australia
| | - Andrew Maiorana
- Curtin School of Allied Health, Curtin University, Perth, Western Australia, Australia
- Exercise Physiology Department, Fiona Stanley Hospital, Perth, Western Australia, Australia
| | - Tracy McCaffrey
- Department of Nutrition, Dietetics and Food, Monash University, Melbourne, Victoria, Australia
| | - Graham Hillis
- Department of Cardiology, Royal Perth Hospital, Perth, Western Australia, Australia
- School of Medicine and Pharmacology, The University of Western Australia, Perth, Western Australia, Australia
| | - Jason Bonson
- College of Medicine and Public Health, Rural and Remote Health, Flinders University, Darwin, Northern Territory, Australia
| | - Hui Jun Chih
- Curtin School of Population Health, Curtin University, Perth, Western Australia, Australia
| | - Himanshu Gupta
- College of Medicine and Public Health, Rural and Remote Health, Flinders University, Darwin, Northern Territory, Australia
| | - Scarlett Holmes
- Physical Activity and Well-being Research Group, Enable Institute, Curtin University, Perth, Western Australia, Australia
- Curtin School of Population Health, Curtin University, Perth, Western Australia, Australia
| | - Kate Hunt
- Institute for Social Marketing, University of Stirling, Stirling, UK
| | - Deborah A Kerr
- Curtin School of Population Health, Curtin University, Perth, Western Australia, Australia
| | - Dominika Kwaśnicka
- NHMRC CRE in Digital Technology to Transform Chronic Disease Outcomes, Melbourne School of Population and Global Health, The University of Melbourne, Melbourne, Victoria, Australia
- Faculty of Psychology, SWPS University of Social Sciences and Humanities, Warsaw, Poland
| | - Marshall Makate
- Curtin School of Population Health, Curtin University, Perth, Western Australia, Australia
| | - Joanne McVeigh
- Physical Activity and Well-being Research Group, Enable Institute, Curtin University, Perth, Western Australia, Australia
- Curtin School of Allied Health, Curtin University, Perth, Western Australia, Australia
| | - Joanna C Moullin
- Curtin School of Population Health, Curtin University, Perth, Western Australia, Australia
| | - Brendan J Smith
- Physical Activity and Well-being Research Group, Enable Institute, Curtin University, Perth, Western Australia, Australia
- Curtin School of Population Health, Curtin University, Perth, Western Australia, Australia
| | - Lee Wharton
- Exercise and Nutrition Sciences, Queensland University of Technology, Brisbane, Queensland, Australia
| | - Neil Wharton
- Exercise and Nutrition Sciences, Queensland University of Technology, Brisbane, Queensland, Australia
| | - Eleanor Quested
- Physical Activity and Well-being Research Group, Enable Institute, Curtin University, Perth, Western Australia, Australia
- Curtin School of Population Health, Curtin University, Perth, Western Australia, Australia
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Macaulay L, O'Dolan C, Avenell A, Carroll P, Cotton S, Dombrowski S, Elders A, Goulao B, Gray C, Harris FM, Hunt K, Kee F, MacLennan G, McDonald MD, McKinley M, Skinner R, Torrens C, Tod M, Turner K, van der Pol M, Hoddinott P. Effectiveness and cost-effectiveness of text messages with or without endowment incentives for weight management in men with obesity (Game of Stones): study protocol for a randomised controlled trial. Trials 2022; 23:582. [PMID: 35869503 PMCID: PMC9306253 DOI: 10.1186/s13063-022-06504-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2022] [Accepted: 07/01/2022] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Obesity increases the risk of type 2 diabetes, heart disease, stroke, mobility problems and some cancers, and its prevalence is rising. Men engage less than women in existing weight loss interventions. Game of Stones builds on a successful feasibility study and aims to find out if automated text messages with or without endowment incentives are effective and cost-effective for weight loss at 12 months compared to a waiting list comparator arm in men with obesity. METHODS A 3-arm, parallel group, assessor-blind superiority randomised controlled trial with process evaluation will recruit 585 adult men with body mass index of 30 kg/m2 or more living in and around three UK centres (Belfast, Bristol, Glasgow), purposively targeting disadvantaged areas. Intervention groups: (i) automated, theory-informed text messages daily for 12 months plus endowment incentives linked to verified weight loss targets at 3, 6 and 12 months; (ii) the same text messages and weight loss assessment protocol; (iii) comparator group: 12 month waiting list, then text messages for 3 months. The primary outcome is percentage weight change at 12 months from baseline. Secondary outcomes at 12 months are as follows: quality of life, wellbeing, mental health, weight stigma, behaviours, satisfaction and confidence. Follow-up includes weight at 24 months. A health economic evaluation will measure cost-effectiveness over the trial and over modelled lifetime: including health service resource-use and quality-adjusted life years. The cost-utility analysis will report incremental cost per quality-adjusted life years gained. Participant and service provider perspectives will be explored via telephone interviews, and exploratory mixed methods process evaluation analyses will focus on mental health, multiple long-term conditions, health inequalities and implementation strategies. DISCUSSION The trial will report whether text messages (with and without cash incentives) can help men to lose weight over 1 year and maintain this for another year compared to a comparator group; the costs and benefits to the health service; and men's experiences of the interventions. Process analyses with public involvement and service commissioner input will ensure that this open-source digital self-care intervention could be sustainable and scalable by a range of NHS or public services. TRIAL REGISTRATION ISRCTN 91974895 . Registered on 14/04/2021.
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Affiliation(s)
- Lisa Macaulay
- NMAHP Research Unit, Stirling University, Pathfoot Building, Stirling, FK9 4LA, UK.
| | - Catriona O'Dolan
- NMAHP Research Unit, Stirling University, Pathfoot Building, Stirling, FK9 4LA, UK
| | - Alison Avenell
- Health Services Research Unit, 3Rd Floor Health Sciences Building, Foresterhill, Aberdeen, AB25 2ZD, UK
| | - Paula Carroll
- Department Sport & Exercise Science, Waterford Institute of Technology, Main Campus Cork RoadCo. Waterford, Waterford City, Ireland
| | - Seonaidh Cotton
- CHaRT, HRSU, 3Rd Floor Health Sciences Building, Foresterhill, Aberdeen, AB25 2ZD, UK
| | - Stephan Dombrowski
- Faculty of Kinesiology, University of New Brunswick, 3 Bailey Drive, P.O. Box 4400, Fredericton, NB, E3B 5A3, Canada
| | - Andrew Elders
- NMAHP Research Unit, Glasgow Caledonian University, Govan Mbeki Building, Cowcaddens Road, G4 0BA, Glasgow, UK
| | - Beatriz Goulao
- CHaRT, HRSU, 3Rd Floor Health Sciences Building, Foresterhill, Aberdeen, AB25 2ZD, UK
| | - Cindy Gray
- School of Social and Political Sciences, University of Glasgow, 25-29 Bute Gardens, Glasgow, G12 8RS, UK
| | - Fiona M Harris
- School of Health & Life Sciences, University of the West of Scotland, High Street, Paisley, Renfrewshire, PA1 2BE, UK
| | - Kate Hunt
- Institute for Social Marketing and Health, Pathfoot Building, University of Stirling, Stirling, FK9 4LA, UK
| | - Frank Kee
- Centre for Public Health, UKCRC Centre of Excellence for Public Health Research (NI), Institute Clinical Sciences A, Grosvenor Road, Belfast, BT12 6BJ, Northern Ireland
| | - Graeme MacLennan
- CHaRT, HRSU, 3Rd Floor Health Sciences Building, Foresterhill, Aberdeen, AB25 2ZD, UK
| | | | - Michelle McKinley
- Queen's University Belfast, University Road, Belfast, BT7 1NN, Northern Ireland
| | | | - Claire Torrens
- NMAHP Research Unit, Stirling University, Pathfoot Building, Stirling, FK9 4LA, UK
| | - Martin Tod
- Men's Health Forum, 49-51 East Rd, Hoxton, London, N1 6AH, UK
| | - Katrina Turner
- Bristol Medical School, University of Bristol, Canynge Hall, 39 Whatley Road, Bristol, BS8 2PS, UK
| | - Marjon van der Pol
- Health Economics Research Unit, University of Aberdeen, Polwarth Building, Foresterhill, Aberdeen, AB25 2ZD, UK
| | - Pat Hoddinott
- NMAHP Research Unit, Stirling University, Pathfoot Building, Stirling, FK9 4LA, UK
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Veauvy CM, Walsh PJ, McDonald MD. Effect of elevated ammonia on tissue nitrogen metabolites in the ureotelic gulf toadfish (Opsanus beta) and the ammoniotelic midshipman (Porichthys notatus). Physiol Biochem Zool 2009; 82:345-52. [PMID: 19072135 DOI: 10.1086/588829] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [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
We investigated possible biochemical pathways explaining extreme ammonia tolerance by the gulf toadfish and specifically tested the prediction that the gulf toadfish Opsanus beta is more tolerant than the plainfin midshipman Porichthys notatus, two confamilial species, because it reverses brain glutamine accumulation during high ammonia exposure. This prediction stems from previous studies demonstrating that gulf toadfish produce urea from glutamine, a pathway not present in the ammoniotelic midshipman. Our results show that at the same water NH(3) concentration, ammonia increases more from control levels in brains of midshipman than toadfish. After 48 h of exposure to 50% of their respective LC(50) (96 h) value for ammonia, toadfish are able to return the ammonia-induced increase in brain glutamine back to control values, reducing brain glutamine by 2,500 micromol kg(-1). However, in midshipman, brain glutamine remains significantly elevated from control throughout the experiment. Toadfish exposed to 33% of their LC(50) (96 h) showed an initial increase in whole body urea, which is then reduced at a rate of 104 micromol kg fish(-1) h(-1) and could be directly excreted into the water. We discuss how the special handling of glutamine in toadfish may explain in part their great tolerance to ammonia.
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Affiliation(s)
- C M Veauvy
- University of Miami, Coral Gables, Florida 33124, USA.
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Abstract
This review summarizes what is currently known about urea transporters in fishes in the context of their physiology and evolution within the vertebrates. The existence of urea transporters has been investigated in red blood cells and hepatocytes of fish as well as in renal and branchial cells. Little is known about urea transport in red blood cells and hepatocytes, in fact, urea transporters are not believed to be present in the erythrocytes of elasmobranchs nor in teleost fish. What little physiological evidence there is for urea transport across fish hepatocytes is not supported by molecular evidence and could be explained by other transporters. In contrast, early findings on elasmobranch renal urea transporters were the impetus for research in other organisms. Urea transport in both the elasmobranch kidney and gill functions to retain urea within the animal against a massive concentration gradient with the environment. Information on branchial and renal urea transporters in teleost fish is recent in comparison but in teleosts urea transporters appear to function for excretion and not retention as in elasmobranchs. The presence of urea transporters in fish that produce a copious amount of urea, such as elasmobranchs and ureotelic teleosts, is reasonable. However, the existence of urea transporters in ammoniotelic fish is curious and could likely be due to their ability to manufacture urea early in life as a means to avoid ammonia toxicity. It is believed that the facilitated diffusion urea transporter (UT) gene family has undergone major evolutionary changes, likely in association with the role of urea transport in the evolution of terrestriality in the vertebrates.
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Affiliation(s)
- M D McDonald
- NIEHS Marine and Freshwater Biomedical Sciences Center, Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, Florida 33149-1098, USA.
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McDonald MD, Wood CM, Grosell M, Walsh PJ. Glucocorticoid receptors are involved in the regulation of pulsatile urea excretion in toadfish. J Comp Physiol B 2004; 174:649-58. [PMID: 15517282 DOI: 10.1007/s00360-004-0456-y] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/05/2004] [Indexed: 10/26/2022]
Abstract
The objectives of this study were to characterize the pattern of pulsatile urea excretion in the gulf toadfish in the wake of exogenous cortisol loading and to determine the receptors involved in the regulation of this mechanism. Toadfish were fitted with indwelling arterial catheters and were infused with isosmotic NaCl for 48 h after which fish were treated with cortisol alone, cortisol + peanut oil, cortisol + RU486 (a glucocorticoid receptor antagonist) or cortisol + spironolactone (a mineralocorticoid receptor antagonist). Upon cortisol loading, fish treated with cortisol alone, cortisol + oil or cortisol + spironolactone experienced a two- to threefold reduction in pulsatile urea excretion. This reduction was due to a decrease in urea pulse size with no effect on pulse frequency compared to values measured during the control NaCl infusion period. In addition, these fish showed an increase in plasma urea concentrations upon treatment. These apparent effects of cortisol treatment were abolished in fish treated with cortisol + RU486. In contrast, these fish showed an increase in pulsatile urea excretion mediated by a twofold increase in pulse size with no change in frequency. Likewise, fish treated with cortisol + RU486 showed a significant decrease in plasma urea concentrations over the course of the experiment. The findings of this study indicate that high levels of cortisol reduce pulsatile urea excretion by decreasing pulse size. In addition, it appears that glucocorticoid receptors and not mineralocorticoid receptors are involved in the regulation of the toadfish pulsatile urea excretion mechanism.
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Affiliation(s)
- M D McDonald
- Department of Biology, McMaster University, Hamilton, Ontario L8S 4K1, Canada.
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Grosell M, McDonald MD, Wood CM, Walsh PJ. Effects of prolonged copper exposure in the marine gulf toadfish (Opsanus beta). I. Hydromineral balance and plasma nitrogenous waste products. Aquat Toxicol 2004; 68:249-262. [PMID: 15159051 DOI: 10.1016/j.aquatox.2004.03.006] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2003] [Revised: 01/26/2004] [Accepted: 03/03/2004] [Indexed: 05/24/2023]
Abstract
Acute (96 h) and prolonged (30 days) copper exposure induced osmoregulatory disturbance and impaired nitrogenous waste excretion in the marine teleost, the gulf toadfish (Opsanus beta), which was found to be extremely tolerant to acute copper exposure with a 96 h LC50 exceeding 340 microM but exhibited disturbed mineral balance in response to both acute and prolonged exposure to approximately 12 microM copper. The main cause of copper toxicity was found to be Na+ and Cl- regulatory failure leading to elevated plasma [Na+] and [Cl-] and osmolality which in turn led to fluid loss from muscle tissue. Analysis of intestinal fluid composition revealed a complicated pattern of effects of copper exposure. Intestinal transport physiology was directly influenced by copper exposure with Cl- absorption being the most sensitive parameter. Evidence for increased Na+ and fluid absorption when the fish exhibited elevated plasma osmolality indicates that the intestine may also exhibit a compensatory response to impairment of branchial transport processes, suggesting at least two target organs (gill and intestine) for copper toxicity in marine fish. Plasma Mg2+ was elevated from approximately 1.5 mM to as much as 4.0 mM, likely as a result of increased branchial permeability. While plasma [ammonia] clearly responded to copper exposure, plasma [urea] exhibited a much more sensitive and pronounced response to both acute and prolonged copper exposure, resulting in as much as a three-fold increase in circulating urea levels. This response is most likely the result of the unique ability of this teleost to convert ammonia to urea.
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Affiliation(s)
- M Grosell
- RSMAS, Division of Marine Biology and Fisheries, University of Miami, 4600 Rickenbacker Causeway, FL 33149-1098, USA.
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Grosell M, McDonald MD, Walsh PJ, Wood CM. Effects of prolonged copper exposure in the marine gulf toadfish (Opsanus beta) II: copper accumulation, drinking rate and Na+/K+ -ATPase activity in osmoregulatory tissues. Aquat Toxicol 2004; 68:263-275. [PMID: 15159052 DOI: 10.1016/j.aquatox.2004.03.007] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2003] [Revised: 01/26/2004] [Accepted: 03/03/2004] [Indexed: 05/24/2023]
Abstract
Gulf toadfish were exposed to sublethal levels of copper (12.8 or 55.2 microM) for 30 days. Drinking in control fish averaged 1 ml kg(-1)h(-1) but exposure to 55.2 microM copper resulted in a complex biophasic pattern with initial (3 h and 1 day) inhibition of drinking rate, followed by an elevation of drinking rate from day 3 onwards. Drinking led to copper accumulation in the intestinal fluids at levels three to five times higher than the ambient copper concentrations, which in turn resulted in intestinal copper accumulation. The gill exhibited more rapid accumulation of copper than the intestine and contributed to early copper uptake leading to accumulation in internal organs. Muscle, spleen and plasma exhibited little if any disturbance of copper homeostasis while renal copper accumulation was evident at both ambient copper concentrations. The liver exhibited the highest copper concentrations and the greatest copper accumulation of all examined internal organs during exposure to 55.2 microM. Elevated biliary copper excretion was evident from measurements of gall bladder bile copper concentrations and appeared to protect partially against internal accumulation in fish exposed to 12.8 microM copper. No inhibition of Na+/K+ -ATPase activity in either gills or intestine was seen despite copper accumulation in these organs. Calculations of inorganic copper speciation suggest that Cu(CO3)(2)2- complexes which dominate in seawater and intestinal fluids are of limited availability for uptake while the low levels of ionic Cu2+, CuOH+ and CuCO3 may be the forms taken up by the gill and the intestinal epithelium.
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Affiliation(s)
- M Grosell
- Division of Marine Biology and Fisheries, RSMAS, University of Miami, 4600 Rickenbacker Causeway, FL 33149-1098, USA.
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McDonald MD. The hospitalist movement: wise or wishful thinking? Nurs Manag (Harrow) 2004; 32:30-1. [PMID: 15103821 DOI: 10.1097/00006247-200103000-00010] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
One-third of all health care expenditures--nearly 5% of the gross domestic product--relates to hospital care. Can hospitalists provide the financial solution?
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Affiliation(s)
- M D McDonald
- Massasoit Community College, Brockton Hospital School of Nursing, Brockton, Mass., USA
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McDonald MD, Wood CM. The effect of chronic cortisol elevation on urea metabolism and excretion in the rainbow trout ( Oncorhynchus mykiss ). J Comp Physiol B 2004; 174:71-81. [PMID: 14586635 DOI: 10.1007/s00360-003-0390-4] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/04/2003] [Indexed: 10/26/2022]
Abstract
The objective of this study was to investigate the possible involvement of cortisol in controlling urea metabolism and excretion in the ammoniotelic rainbow trout (Oncorhynchus mykiss). Trout fitted with dorsal aortic and internal urinary catheters received either no implant (control), or were implanted with coconut oil (sham), cortisol in coconut oil, RU486, a glucocorticoid receptor blocker, in coconut oil, or cortisol+RU486 in coconut oil, and monitored over 72 h. Rainbow trout treated with cortisol (+/- RU486) had similarly elevated plasma cortisol concentrations that were six fold greater than in control and sham fish. Elevated circulating cortisol concentrations caused a three-fold rise in plasma and urine urea concentrations, which was blocked by RU486. Similarly, a positive correlation between plasma cortisol and plasma urea concentrations was observed in fish treated with cortisol alone but not in fish treated with cortisol+RU486. Cortisol treatment caused an elevation in branchial (two fold higher) and urinary (three fold higher) excretion rates of urea compared to sham-implanted fish, which was prevented by treatment with RU486. However, as branchial and renal clearance were unaffected, there appears to be no stimulation or inhibition of urea excretion mechanisms in the gill or kidney separate from effects due to changes in plasma urea concentrations. Thus, cortisol and glucocorticoid receptors appear to be involved in the regulation of endogenous urea production but not in the control of urea excretory mechanisms in the ammoniotelic trout.
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Affiliation(s)
- M D McDonald
- McMaster University, Department of Biology, Hamilton, Ontario, L8S 4K1, Canada.
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McDonald MD, Walsh PJ, Wood CM. Branchial and renal excretion of urea and urea analogues in the plainfin midshipman, Porichthys notatus. J Comp Physiol B 2002; 172:699-712. [PMID: 12444469 DOI: 10.1007/s00360-002-0299-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/13/2002] [Indexed: 10/27/2022]
Abstract
This study investigated whether urea transport mechanisms were present in the gills of the ammoniotelic plainfin midshipman (Porichthys notatus), similar to those recently documented in its ureotelic relative (family Batrachoididae), the gulf toadfish (Opsanus beta). Midshipmen were fitted with internal urinary and caudal artery catheters for repetitive sampling of urine and blood in experiments and radiolabeled urea analogues ([(14)C]-thiourea and [(14)C]-acetamide) were used to evaluate the handling of these substances. Isosmotically balanced infusions of urea were used to raise plasma and urine urea concentrations to levels surpassing physiological levels by 8.5-fold and 6.4-fold, respectively. Despite these high urea levels, there was no observable transport maximum in either renal or branchial urea excretion rate, a result mirrored by the total uptake of fish exposed to a range of environmental urea concentrations. Permeability to urea appeared to be symmetrical in the two directions. At comparable plasma concentrations the branchial clearance rate of acetamide was 74% that of urea while branchial clearance rate of thiourea was 55% that of urea. For influx, the comparable values were 60% and 36%, indicating the same pattern. In contrast, the secretion clearance rate of acetamide by the kidney was 56% that of urea while the rate of thiourea secretion clearance was 137% greater than that of urea, with both urea and thiourea being more concentrated in the urine than in the plasma. In addition, the secretion clearance rates of thiourea and urea were significantly greater than those of water and Cl(-), whereas acetamide, water and Cl(-) were found equally in the plasma and urine, appearing to passively equilibrate between the two fluids. Based on our findings, there appear to be two distinct transport mechanisms involved in urea excretion in the plainfin midshipmen, one in the gill (a facilitated diffusion type transporter) and one in the kidney (an active transport mechanism), each of which does not saturate even at plasma urea concentrations that greatly exceed physiological levels. These transporters appear to be similar to those in the midshipman's ureotelic relative, the gulf toadfish.
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Affiliation(s)
- M D McDonald
- Department of Biology, McMaster University, Hamilton, Ontario, Canada.
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Wood CM, Warne JM, Wang Y, McDonald MD, Balment RJ, Laurent P, Walsh PJ. Do circulating plasma AVT and/or cortisol levels control pulsatile urea excretion in the gulf toadfish (Opsanus beta)? Comp Biochem Physiol A Mol Integr Physiol 2001; 129:859-72. [PMID: 11440872 DOI: 10.1016/s1095-6433(01)00340-3] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.3] [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: 10/18/2022]
Abstract
Previous work has shown that pulsatile urea excretion at the gills of the gulf toadfish is due to periodic activation of a facilitated diffusion transport system with molecular and pharmacological similarity to the UT-A transport system of the mammalian kidney. In mammals, AVP and glucocorticoids are two important endocrine regulators of this system. The present study focused on the potential role of circulating AVT (the teleost homologue of AVP) and cortisol levels as possible triggers for urea pulses. Long-term (34-84 h) monitoring of plasma levels by repetitive sampling at 2-h intervals from chronic cannulae in individual toadfish demonstrated that circulating AVT concentrations are low (10(-12)-10(-11) M), and show no relationship to the occurrence of natural urea pulses. In contrast, plasma cortisol levels decline greatly prior to natural pulses and rise rapidly thereafter. AVT injections into the caudal artery or ventral aorta elicited pulse events, but these were extremely small (1-10%) relative to natural pulses, and occurred only at unphysiological dose levels (10(-9) M in the plasma). AVP was a partial agonist, but isotocin, insulin-like growth factor-1, and atrial natriuretic peptide were without effect at the same concentration. Artificially raising plasma cortisol levels by cortisol injection tended to reduce responsiveness to AVT. Pharmacological reduction of plasma cortisol levels by metyrapone injection elicited small pulses similar to those caused by AVT. Following such pulse events, AVT was ineffective in inducing pulses. We conclude that decreases in circulating cortisol play an important permissive role in urea pulsing, but that circulating AVT levels are not involved.
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Affiliation(s)
- C M Wood
- Division of Marine Biology and Fisheries, Rosenstiel School of Marine and Atmospheric Science, NIEHS Marine and Freshwater Biomedical Sciences Center, University of Miami, Miami, FL 33149, USA.
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McDonald MD, Wood CM, Wang Y, Walsh PJ. Differential branchial and renal handling of urea, acetamide and thiourea in the gulf toadfish Opsanus beta: evidence for two transporters. J Exp Biol 2000; 203:1027-37. [PMID: 10683162 DOI: 10.1242/jeb.203.6.1027] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.9] [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: 11/20/2022]
Abstract
The possible presence of a urea transporter in the kidney of the gulf toadfish (Opsanus beta) and further characterization of the pulsatile facilitated transporter previously identified in its gills were investigated by comparing the extra-renal and renal handling of two urea analogues with the handling of urea. Toadfish were fitted with caudal artery and indwelling urinary ureteral catheters and injected with an iso-osmotic dose of (14)C-labelled urea analogue (acetamide or thiourea) calculated to bring plasma analogue concentrations close to plasma urea concentrations. Branchial permeabilities to urea, acetamide and thiourea were similar during non-pulsing periods and all increased during pulse events, although urea permeability was greater than analogue permeability during pulses. The incidence and magnitude of acetamide and urea pulses at the gills were significantly correlated, acetamide pulses being 35-50 % of the size of urea pulses. However, the thiourea and urea pulses at the gills were only weakly correlated, thiourea pulses being less than 16 % of the size of urea pulses. Thiourea inhibited branchial urea excretion by reducing the pulse frequency. The renal handling of thiourea and urea were similar in that both substances were more concentrated in the urine than in the plasma, whereas acetamide was found in equal concentrations in the urine and plasma. Urea and thiourea were secreted 2-3 times more effectively than Cl(-) and water, whereas acetamide was secreted at a similar relative rate. The differential handling of the urea analogues by the gills and kidney indicates the presence of a different, possibly unique, transporter in the kidney. The movement of thiourea and urea into the renal tubule against an apparent concentration gradient suggests the presence of an active transport mechanism.
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Affiliation(s)
- M D McDonald
- McMaster University, Life Science Building, Hamilton, Ontario, Canada.
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Abstract
There is an increasing awareness of the clinical problems associated with ultra-high-molecular-weight polyethylene (UHMWPE) wear and failure in orthopedics. To better understand the reasons for wear and failure, methods were developed using polarized light microscopic analysis and backscattered electron (BSE) imaging with correlated elemental analysis to distinguish the contributions of wear, creep, and third-body particulate. This study determined that microscopic metal particles (< 10 microns) previously not observed with the stereomicroscope could be easily observed with the BSE technique. BSE imaging identified embedded metal in 5/5 of the tibial and 2/4 of the acetabular inserts, which were thought to be free of metal debris after stereoscopic examination. Correlated elemental analysis showed that the microscopic particles could be traced to the elements known to be present in the porous coatings of the retrieved uncemented implants. Creep was distinguished from wear in the total hip and total knee inserts by using polarized light microscopic techniques. Continued development of polarized light microscopic techniques applied in this investigation should assist biomaterials experts in the future to better distinguish wear and creep in retrieved clinical inserts. The correlated BSE and elemental analysis will assist in determining the roll of microscopic third-body particular in wear and osteolysis in total joint replacement.
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Affiliation(s)
- M D McDonald
- Bone and Joint Research Laboratory (151F), VA Medical Center, Salt Lake City, Utah 84148
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McDonald MD. Elements of a national health information infrastructure. Healthc Inf Manage 1994; 8:19-22. [PMID: 10184034] [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]
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McDonald MD. Telecognition for improving health. Healthc Forum J 1994; 37:18-21. [PMID: 10132154] [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)
- M D McDonald
- Environmental Science and Policy Institute, Lexington, MA
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McDonald MD, Blum HL. HOT: the emergence of health oriented telecommunication applications. Healthc Inform 1992; 9:62-4, 66, 68. [PMID: 10122400] [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: 02/11/2023]
Abstract
America has benefited from decades of outstanding health services. However, the American health system now is in crisis--with runaway medical cost inflation, hospital closures, and unacceptably high and increasing numbers of uninsured people. Key solutions for bringing the health system into balance remain untapped in the potentials of health-oriented telecommunication, or HOT applications. HOT applications could rally the immense unused personal resources of the public for improving their own health, help upgrade the delivery and efficiency of healthcare and its administration, and improve public health's ability to deal with present and emerging system-level problems impacting health.
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