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Quilliam C, Green E, Rasiah RL, Sheepway L, Seaton C, Moore L, Bailie J, Matthews KM, Ferns J, Debenham J, Taylor C, Fitzgerald K, Ridd M. University staff perspectives on determinants of high-quality health professions student placements in regional, rural and remote Australia: protocol for a mixed-method study. BMJ Open 2024; 14:e077079. [PMID: 38448071 PMCID: PMC10916158 DOI: 10.1136/bmjopen-2023-077079] [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: 06/25/2023] [Accepted: 02/13/2024] [Indexed: 03/08/2024] Open
Abstract
INTRODUCTION In rural areas, work-integrated learning in the form of health student placements has several potential benefits, including contributing to student learning, enhancing rural health service capacity and attracting future rural health workforce. Understanding what constitutes a high-quality rural placement experience is important for enhancing these outcomes. There is no current standardised definition of quality in the context of rural health placements, nor is there understanding of how this can be achieved across different rural contexts. This study is guided by one broad research question: what do university staff believe are the determinants of high-quality health professions student placements in regional, rural and remote Australia? METHODS AND ANALYSIS This study will adopt a convergent mixed-method design with two components. Component A will use explanatory sequential mixed methods. The first phase of component A will use a survey to explore determinants that contribute to the development of high-quality health student placements from the perspective of university staff who are not employed in University Departments of Rural Health and are involved in the delivery of health student education. The second phase will use semistructured interviews with the same stakeholder group (non-University Department of Rural Health university staff) to identify the determinants of high-quality health student placements. Component B will use a case study Employing COnceptUal schema for policy and Translation Engagement in Research mind mapping method to capture determinants that contribute to the development of high-quality health student placements from the perspective of University Department of Rural Health university staff. ETHICS AND DISSEMINATION The University of Melbourne Human Ethics Committee approved the study (2022-23201-33373-5). Following this, seven other Australian university human research ethics committees provided external approval to conduct the study. The results of the study will be presented in several peer-review publications and summary reports to key stakeholder groups.
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Affiliation(s)
- Claire Quilliam
- Department of Rural Health, The University of Melbourne, Shepparton, Victoria, Australia
| | - Elyce Green
- Charles Sturt University, Wagga Wagga, New South Wales, Australia
| | - Rohan L Rasiah
- Western Australian Centre for Rural Health, The University of Western Australia, Karratha, Western Australia, Australia
| | - Lyndal Sheepway
- La Trobe Rural Health School, La Trobe University, Wodonga, Victoria, Australia
| | - Catherine Seaton
- Centre for Rural and Remote Health, James Cook University, Mount Isa, Queensland, Australia
| | - Leigh Moore
- Flinders University Rural and Remote Health, Flinders University, Darwin, Northern Territory, Australia
| | - Jodie Bailie
- University Centre for Rural Health, The University of Sydney, Lismore, New South Wales, Australia
- School of Public Health, The University of Sydney, Sydney, New South Wales, Australia
| | - Kylie Maree Matthews
- Majarlin Kimberley Centre for Remote Health, The University of Notre Dame Australia, Broome, Western Australia, Australia
| | - Jane Ferns
- Department of Rural Health, The University of Newcastle, Taree, New South Wales, Australia
| | - James Debenham
- Majarlin Kimberley Centre for Remote Health, The University of Notre Dame Australia, Broome, Western Australia, Australia
| | - Carolyn Taylor
- La Trobe Rural Health School, La Trobe University, Bendigo, Victoria, Australia
| | - Kathryn Fitzgerald
- Western Australian Centre for Rural Health, The University of Western Australia, Geraldton, Western Australia, Australia
| | - Melissa Ridd
- Flinders University Rural and Remote Health, Flinders University, Darwin, Northern Territory, Australia
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Green E, Quilliam C, Sheepway L, Hays CA, Moore L, Rasiah RL, Bailie J, Howard C, Hyde S, Inyang I, Matthews K, Ferns J, Brown LJ, Jones S, Collett M. Identifying features of quality in rural placements for health students: scoping review. BMJ Open 2022; 12:e057074. [PMID: 35396299 PMCID: PMC8995951 DOI: 10.1136/bmjopen-2021-057074] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [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] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
OBJECTIVES To explore and synthesise the evidence relating to features of quality in rural health student placements. DESIGN Scoping review. DATA SOURCES MEDLINE, CINAHL, Embase, ProQuest, Informit, Scopus, ERIC and several grey literature data sources (1 January 2005 to 13 October 2020). STUDY SELECTION The review included peer-reviewed and grey literature from Organisation for Economic Co-operation and Development listed countries that focused on quality of health student placements in regional, rural and remote areas. DATA EXTRACTION Data were extracted regarding the methodological and design characteristics of each data source, and the features suggested to contribute to student placement quality under five categories based on a work-integrated learning framework. RESULTS Of 2866 resulting papers, 101 were included for data charting and content analysis. The literature was dominated by medicine and nursing student placement research. No literature explicitly defined quality in rural health student placements, although proxy indicators for quality such as satisfaction, positive experiences, overall effectiveness and perceived value were identified. Content analysis resulted in four overarching domains pertaining to features of rural health student placement quality: (1) learning and teaching in a rural context, (2) rural student placement characteristics, (3) key relationships and (4) required infrastructure. CONCLUSION The findings suggest that quality in rural health student placements hinges on contextually specific features. Further research is required to explore these findings and ways in which these features can be measured during rural health student placements.
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Affiliation(s)
- Elyce Green
- Three Rivers University Department of Rural Health, Charles Sturt University, Wagga Wagga, New South Wales, Australia
| | - Claire Quilliam
- Department of Rural Health, The University of Melbourne, Shepparton, Victoria, Australia
| | - Lyndal Sheepway
- La Trobe Rural Health School, La Trobe University, Wodonga, Victoria, Australia
| | - Catherine A Hays
- Centre for Rural and Remote Health, James Cook University, Mount Isa, Queensland, Australia
| | - Leigh Moore
- Rural and Remote Health, Flinders University, Darwin, Northern Territory, Australia
| | - Rohan L Rasiah
- Western Australian Centre for Rural Health, The University of Western Australia, Karratha, Western Australia, Australia
| | - Jodie Bailie
- University Centre for Rural Health, The University of Sydney, Lismore, New South Wales, Australia
| | - Christine Howard
- Three Rivers University Department of Rural Health, Charles Sturt University, Wagga Wagga, New South Wales, Australia
| | - Sarah Hyde
- Joint Program in Medicine School of Rural Medicine, Charles Sturt University, Orange, New South Wales, Australia
| | - Imo Inyang
- Centre for Rural Health, University of Tasmania, Launceston, Tasmania, Australia
| | - Kylie Matthews
- Majarlin Kimberley Centre for Remote Health, The University of Notre Dame, Broome, Western Australia, Australia
| | - Jane Ferns
- Department of Rural Health, The University of Newcastle, Taree, New South Wales, Australia
| | - Leanne J Brown
- Department of Rural Health, The University of Newcastle, Taree, New South Wales, Australia
| | - Sara Jones
- Department of Rural Health, University of South Australia, Whyalla, South Australia, Australia
| | - Marjorie Collett
- Western Australian Centre for Rural Health, The University of Western Australia, Geraldton, Western Australia, Australia
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See L, Rasiah RL, Laing R, Thompson SC. Considerations in Planning Physical Activity for Older Adults in Hot Climates: A Narrative Review. Int J Environ Res Public Health 2021; 18:ijerph18031331. [PMID: 33540584 PMCID: PMC7908220 DOI: 10.3390/ijerph18031331] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Accepted: 01/26/2021] [Indexed: 12/25/2022]
Abstract
Regular physical activity has multiple health benefits for both the prevention and management of disease, including for older adults. However, additional precautions are needed with ageing given physiological changes and the increasing prevalence of comorbidities. Hot ambient temperatures increase the risks of exercise at any age, but are particularly important given thermoregulatory changes in older people. This narrative review informs planning of physical activity programs for older people living in rural areas with very hot climates for a period of the year. A multi-database search of peer-reviewed literature was undertaken with attention to its relevance to Australia, starting with definitions and standard advice in relation to physical activity programming and the incremental limitations imposed by age, rurality, and extreme heat. The enablers of and barriers to increasing physical activities in older adults and how they can be modified for those living in extreme hot climates is described. We describe multiple considerations in program design to improve safety, adherence and sustaining physical activity, including supervision, simple instructions, provision of reminders, social support, encouraging self-efficacy. Group-based activities may be preferred by some and can accommodate special populations, cultural considerations. Risk management is an important consideration and recommendations are provided to assist program planning.
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Affiliation(s)
- Lydia See
- Western Australian Centre for Rural Health, School of Population and Global Health, University of Western Australia, Crawley 6009, Australia; (R.L.R.); (R.L.); (S.C.T.)
- Oral Health Centre of Western Australia, School of Dentistry, University of Western Australia, Nedlands 6009, Australia
- Correspondence: ; Tel.: +61-8-6457-4400
| | - Rohan L. Rasiah
- Western Australian Centre for Rural Health, School of Population and Global Health, University of Western Australia, Crawley 6009, Australia; (R.L.R.); (R.L.); (S.C.T.)
| | - Rachael Laing
- Western Australian Centre for Rural Health, School of Population and Global Health, University of Western Australia, Crawley 6009, Australia; (R.L.R.); (R.L.); (S.C.T.)
| | - Sandra C. Thompson
- Western Australian Centre for Rural Health, School of Population and Global Health, University of Western Australia, Crawley 6009, Australia; (R.L.R.); (R.L.); (S.C.T.)
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Peterson GM, Fitzmaurice KD, Rasiah RL, Kruup H. Marketing of rural and remote pharmacy practice via the digital medium. J Clin Pharm Ther 2010; 35:409-14. [PMID: 20831544 DOI: 10.1111/j.1365-2710.2009.01110.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
AIM The shortage of community and hospital pharmacists is particularly acute in rural and remote areas of Australia. Pharmacy students, in particular, as those who may be able to alleviate this shortage, need to be made more aware of the challenges and rewards of rural pharmacy practice. A marketing tool was developed to promote rural and remote pharmacy practice as a career option. A DVD was produced from interviews with health professionals working in rural and remote areas of Australia. This DVD will complement current rural practical placements, which have been incorporated into the curriculum of Australian schools of pharmacy. METHODS Interviews were conducted with healthcare professionals from areas in Tasmania, Northern Queensland and the Northern Territory. Interviewees included pharmacists, graduate pharmacists, pharmacy students, aboriginal health workers and a general practitioner. Each of the interviewees was able to provide personal accounts of experiences in rural and remote healthcare, and roles and opportunities for pharmacists. A final draft of the DVD was shown to University of Tasmania students to assess the impact and quality of the production. RESULTS A number of common themes arose from interviewing and these were subsequently converted into five key chapters of the DVD - Lifestyle, Belonging, Diversity, Indigenous Health and 'Give it a go'. The final DVD, produced from over 15 h of footage, runs for 35 min. Students reported positive feedback on both the technical quality and the information contained within the DVD; 37% of students who viewed the DVD felt that it increased their awareness of what rural pharmacy has to offer. CONCLUSIONS The rural pharmacy, 'Enjoy the Lifestyle' DVD can be used to increase awareness of rural and remote pharmacy practice to students and other pharmacists, and complements other pharmacy workforce strategies for rural and remote areas of Australia. It could also be a useful approach for adaptation in other countries.
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Affiliation(s)
- G M Peterson
- Unit for Medication Outcomes Research and Education, School of Pharmacy, University of Tasmania, Hobart, Australia
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Peterson GM, Fitzmaurice KD, Kruup H, Jackson SL, Rasiah RL. Cardiovascular risk screening program in Australian community pharmacies. ACTA ACUST UNITED AC 2010; 32:373-80. [PMID: 20217476 DOI: 10.1007/s11096-010-9379-8] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2008] [Accepted: 03/01/2010] [Indexed: 01/22/2023]
Abstract
OBJECTIVE To assess the suitability of Australian community pharmacies as cardiovascular disease risk profile screening centres and evaluate whether community pharmacists can play an important role in detecting, educating and referring screened individuals at high risk of cardiovascular disease. SETTING 14 Australian community pharmacies. METHOD Opportunistic cardiovascular disease risk profiling for members of the public aged greater than 30 years with no existing cardiovascular diseases was performed. All major cardiovascular risk factors were measured. Exercise habits, existing conditions and therapy, and family history were also assessed. The results were used to calculate each subject's 10-year risk of developing cardiovascular events, based on Framingham Risk Equations (New Zealand tables). Each subject's knowledge of cardiovascular risk factors was assessed using a multiple-choice questionnaire. Written educational materials and verbal counselling were provided. Referral to a doctor for further assessment was recommended as appropriate. The screened individuals were followed up via mailed out questionnaire. A random sample of individuals at elevated risk was phoned to assess for outcomes of the screening and referral process. MAIN OUTCOME MEASURES Risk of developing cardiovascular disease and knowledge of cardiovascular risk factors. RESULTS A total of 655 individuals (71.4% female) were screened for cardiovascular disease risk factors. Ages ranged from 30 to 90 years (median: 54 years) and 14.2% were smokers. Of the individuals screened, 28.1% had a 10-year risk of developing cardiovascular disease greater than 15%, including 6.9% who had a 10-year risk above 30%. The median calculated 10-year risk of developing cardiovascular disease was 9.5%. Approximately one-third of the individuals had elevated blood pressure, and almost two-thirds were either overweight or obese. The mean total serum cholesterol was 5.31 mmol/l, with 40% of individuals having a level above 5.5 mmol/l and 20% having a high-density lipoprotein cholesterol level below 1.0 mmol/l. There was a statistically significant improvement in the knowledge of cardiovascular disease risk factors at follow-up. Almost half of the contacted high-risk subjects reported lifestyle changes or started drug therapy following re-testing by their general practitioner. CONCLUSION A pharmacy-based cardiovascular disease risk profile screening and education program has the potential to identify and refer many undiagnosed individuals at high risk of cardiovascular events, and help contain the burden of heart disease.
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Affiliation(s)
- Gregory M Peterson
- Unit for Medication Outcomes Research and Education, School of Pharmacy, University of Tasmania, Locked Bag 26, Hobart, TAS, 7001, Australia.
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Jackson SL, Bereznicki LR, Peterson GM, Marsden KA, Jupe DML, Vial JH, Rasiah RL, Misan G, Williams SM. Accuracy and clinical usefulness of the near-patient testing CoaguChek S international normalised ratio monitor in rural medical practice. Aust J Rural Health 2004; 12:137-42. [PMID: 15315540 DOI: 10.1111/j.1440-1854.2004.00585.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [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: 11/30/2022] Open
Abstract
OBJECTIVE To compare the accuracy and clinical usefulness of the near-patient testing CoaguChek S INR monitor in rural medical practice. DESIGN, SETTING AND MAIN OUTCOME MEASURES: General practices were identified through Australian university departments of rural health. Study investigators trained general practitioners and/or practice nurses in the use of the CoaguChek S INR monitor. General practices obtained a fingerprick sample for testing with the INR monitor to compare with conventional pathology testing for accuracy. An evaluation questionnaire was administered to users of the machine to assess ease of use and clinical usefulness. RESULTS A total of 169 patients from 15 general practice sites provided 401 paired (CoaguChek S and laboratory) INR results. The CoaguChek S was found to be accurate when compared to laboratory INR (r = 0.89), despite complicating variables such as multiple users of the monitor and multiple laboratories used for comparison with the CoaguChek S INR. Overall, 88% of dual INR measurements were within 0.5 INR units of each other. For laboratory INR </= 1.9, 2.0-3.5 and >/= 3.6, 97%, 90% and 57% of readings were within 0.5 INR units, respectively. Clinical agreement occurred 93% and 90% of the time against published expanded and narrow criteria, respectively. CONCLUSIONS The routine use of near-patient testing, with appropriate training and quality assurance programs, has the potential to increase the safety and efficacy of warfarin therapy in rural and remote communities.
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Affiliation(s)
- Shane L Jackson
- School of Pharmacy, University of Tasmania, Hobart, Tasmania
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Abstract
Using NONMEM, the population pharmacokinetics of perhexiline were studied in 88 patients (34 F, 54 M) who were being treated for refractory angina. Their mean +/- SD (range) age was 75 +/- 9.9 years (46-92), and the length of perhexiline treatment was 56 +/- 77 weeks (0.3-416). The sampling time after a dose was 14.1 +/- 21.4 hours (0.5-200), and the perhexiline plasma concentrations were 0.39 +/- 0.32 mg/L (0.03-1.56). A one-compartment model with first-order absorption was fitted to the data using the first-order (FO) approximation. The best model contained 2 subpopulations (obtained via the $MIXTURE subroutine) of 77 subjects (subgroup A) and 11 subjects (subgroup B) that had typical values for clearance (CL/F) of 21.8 L/h and 2.06 L/h, respectively. The volumes of distribution (V/F) were 1470 L and 260 L, respectively, which suggested a reduction in presystemic metabolism in subgroup B. The interindividual variability (CV%) was modeled logarithmically and for CL/F ranged from 69.1% (subgroup A) to 86.3% (subgroup B). The interindividual variability in V/F was 111%. The residual variability unexplained by the population model was 28.2%. These results confirm and extend the existing pharmacokinetic data on perhexiline, especially the bimodal distribution of CL/F manifested via an inherited deficiency in hepatic and extrahepatic CYP2D6 activity.
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Affiliation(s)
- R Hussein
- School of Pharmacy and The Australian Center for Pediatric Pharmacokinetics, The University of Queensland, St Lucia, Queensland, Australia
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Abstract
OBJECTIVE The purpose of this study was to determine the population pharmacokinetics of magnesium from sparse observational data in patients with preeclampsia. STUDY DESIGN Serum magnesium concentrations (1-11 per patient) were obtained retrospectively from the records of 116 patients with preeclampsia who had a loading dose of magnesium sulfate (16 or 20 mmol), followed by a maintenance dose (1 mmol/h) over an average of 28 hours. Population clearance, volume of distribution, and the baseline magnesium concentration were estimated using the NONMEM program. RESULTS The following population typical values, together with the interpatient variability (expressed as coefficient of variation) were obtained with the use of a 1-compartment model: systemic clearance, 4.28 L/h (37.3%); volume of distribution, 32.3 L (32.1%); baseline concentration, 0.811 mmol/L (18.5%). The average half-life was 5.2 hours. Clonus was not obtunded in 4 patients whose serum magnesium concentrations were similar to the average concentration of 1.7 mmol/L. The variability remaining unexplained after the population model was fitted to the data was 6.5% to 10.8%. CONCLUSION This study extended knowledge of the pharmacokinetic disposition of magnesium in preeclampsia. The results are potentially useful for the calculation of loading and maintenance doses, particularly when the relationship between serum concentration and effect in preeclampsia is clarified.
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Affiliation(s)
- F S Chuan
- School of Pharmacy, The University of Queensland, Brisbane, Australia
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Abstract
The placental transfer of red blood cells and solutes in man has been investigated by statistical moment analysis, using the impulse-response technique. Model compounds of different lipophilicity (sucrose, water, antipyrine, propranolol and labetalol) were injected with a vascular reference (labelled red blood cells) as boluses into either the foetal or maternal circulation of a single-pass perfused placental lobule. Maternal and foetal venous outflow fractions were collected at intervals ranging from 1 to 600 s. Perfusion was conducted at maternal flow rates of 4 and 6 mL min(-1) and foetal flow rates of 2 and 3 mL min(-1), respectively, to yield a constant materno-foetal flow ratio of 2. The outflow concentration-time profile curves were analysed by statistical moment analysis. The sum of foetal and maternal recovery was close to 100% for red blood cells, sucrose, water and antipyrine, but lower for propranolol and labetalol. The mean transit time (MTT) values ranged from 20 to 500 s. The normalized variance (CV2) for red blood cells in the foetal and maternal circulation of the placenta were in the ranges 2.31 to 3.86 and 2.00 to 2.03, respectively. The shape of the outflow concentration-time profiles after bolus input is consistent with that of vascular residence time models such as the dispersion model. The heterogeneity in red blood cell transit times, as defined by CV2, is greater than in either the perfused leg or perfused liver.
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Affiliation(s)
- I Bernus
- Clinical Research Centre, RBH Research Foundation and Division of Chemical Pathology, Queensland Health Pathology Service, Royal Brisbane Hospital Campus, Australia
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Rasiah RL, Addison RS, Roberts MS, Mortimer RH. An isolated perfused human placental lobule model for multiple indicator dilution studies. J Pharmacol Toxicol Methods 1997; 38:19-25. [PMID: 9339412 DOI: 10.1016/s1056-8719(97)00032-4] [Citation(s) in RCA: 3] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
We describe a method for multiple indicator dilution studies in the isolated perfused human placental lobule developed to investigate the relationships between changes in pressure and flow and solute clearance. A peripheral lobule of a human placenta is perfused with a tissue culture-based medium and the perfusate oxygen tension, arterial and venous pressures, pH and perfusion temperature continuously monitored by a computerized system. Flow rates are readily changed. Bolus injections of vascular, extracellular and water space markers, and study compounds can be made into either maternal or fetal circulations, and precisely timed outflow fractions can be collected with computer-controlled fraction collectors, allowing simultaneous determination of concentration-time profiles of each marker.
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Affiliation(s)
- R L Rasiah
- Conjoint Endocrine Laboratory, Royal Brisbane Hospital, Queensland, Australia
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Westhuyzen J, Graham SD, Rasiah RL, Saltissi D. Simplified sizing of low-density lipoprotein using polyacrylamide gradient gel electrophoresis of plasma. Eur J Clin Chem Clin Biochem 1997; 35:17-9. [PMID: 9156560 DOI: 10.1515/cclm.1997.35.1.17] [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: 02/04/2023]
Abstract
Low-density lipoprotein (LDL) particles can be separated into subfractions according to size by non-denaturing polyacrylamide gradient gel electrophoresis. Established research methods require specialised equipment and are frequently unsuited to the clinical laboratory. In this study, we utilised a colour flat bed scanner in conjunction with shareware image analysis software to compare LDL particle diameters of isolated LDL with LDL in whole plasma. LDL was isolated by ultracentrifugation and electrophoresed on 3-13% gels (Gradipore; Sydney, Australia) for 2400 Volt-hours in parallel with plasma and molecular size standards. Coomassie Blue-stained gels were scanned in reflexive mode using a colour flat-bed scanner and Adobe Photoshop 3.0 software. Density traces of each lane were obtained using NIH Image software (public domain, USA). LDL particle diameters were determined from calibration curves of the log of molecular diameter of standards against migration distance. There was a good correlation between LDL particle diameters obtained using isolated LDL and whole plasma (r = 0.87, P < 0.001; n = 22). However, the group means (+/- S.D.) (24.7 +/- 0.6 and 24.8 +/- 0.5 nm respectively) were statistically different on the paired t-test (P < 0.05). It is unclear whether this numerically small difference is due to alterations in LDL during the longer preparative procedures for LDL, or to matrix effects during electrophoresis of plasma samples. In conclusion, plasma samples stained with Coomassie Blue and scanned with a colour flat bed scanner can conveniently be used for LDL particle sizing by non-denaturing polyacrylamide gradient gel electrophoresis.
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Affiliation(s)
- J Westhuyzen
- Conjoint Internal Medicine Laboratory, Royal Brisbane Hospital, Herston, Australia
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Abstract
The myogenic response is the tendency of certain vessels, most notably small arteries and arterioles, to constrict in response to an increase in intravascular pressure. The effects of propofol on the myogenic response of the isolated pressurized rabbit ear artery were studied in segments preconstricted either with norepinephrine or 5-hydroxytryptamine and subjected to pressure increases from 60 to 100 mm Hg applied either rapidly (jumps over 500 ms) or slowly (ramps over 120 s). In the control experiments the preconstricted vessels initially dilated, then rapidly returned toward their initial diameter. In response to pressure ramps, vessels slowly dilated, but closely retained their resting diameter. Administration of propofol (1.6 x 10(-4) to 1.6 x 10(-3) M) resulted in dilation of the constricted vessels. With pressure jumps vessels had a reduced capacity to recover their initial diameters, and with pressure ramps vessels dilated to greater diameters. When the concentration of vasoconstrictor was increased to antagonize the propofol-induced dilation the myogenicity was not restored. This attenuation of myogenicity, distinct from the drug's vasodilator effect may represent a further mechanism by which anesthetic agents can affect cardiovascular function.
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Affiliation(s)
- R D MacPherson
- Department of Physiology, University of Tasmania, Hobart, Australia
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Abstract
To determine if accidental intraarterial injection of propofol results in vascular damage, the effect of bolus administration of propofol on vascular smooth muscle and the endothelium was investigated using the isolated rabbit ear artery. Ear artery segments, removed from urethane anesthetized rabbits, were perfused with Krebs solution (1 ml.min-1) and pressurized to 60 mmHg before being constricted with extraluminal norepinephrine (1.8-4.2 x 10(-6) M). The external diameter of the vessel was measured by an array of light-dependent diodes. Functional responsiveness was determined by the degree of constriction to norepinephrine and the subsequent dilatation of the artery to intraluminal acetylcholine (2 x 10(-6) M) and glyceryl trinitrate (2 x 10(-6) M), and by the myogenic reactivity to a pressure increase from 60 to 100 mmHg. These responses were measured before and after perfusion with 1% propofol for 120 s. Administration of propofol did not result in any vasoactivity nor did it increase the sensitivity to norepinephrine. Vessels maintained their capacity to dilate to both agents, while the myogenic activity was unaffected. Histologic examination of the propofol exposed vessels showed no changes to smooth muscle structure, and the endothelial layer remained intact.
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Affiliation(s)
- R D MacPherson
- Department of Physiology, University of Tasmania, Australia
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MacPherson RD, McLeod LJ, Rasiah RL. Myogenic response of isolated pressurized rabbit ear artery is independent of endothelium. Am J Physiol 1991; 260:H779-84. [PMID: 2000973 DOI: 10.1152/ajpheart.1991.260.3.h779] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Central ear artery segments, removed from urethan-anesthetized rabbits, were used to assess whether distention activation was dependent on intact and functional endothelium (ENDO). Changes in external arterial diameter were measured with light-dependent diode array mounted above the vessel. After constriction with norepinephrine, slow increases in pressure from 60 to 80 or 100 mmHg performed over 120 s (pressure ramps) failed to initiate distention, but initial diameter was maintained. Rapidly applied (500 ms) pressure increases (pressure jumps) across same pressure ranges gave rise to initial distention and a myogenic response resulting in a return to almost initial diameter while new pressure was maintained for 120 s. Myogenic activity was measured from extent of recovery of vessel to its initial diameter during maintenance of pressure jumps or ramps. Rapid jumps and slow ramps were performed in presence of an intact ENDO and again after ENDO was removed by passage of intraluminal gas. With pressure jumps 60 to 80 mmHg, degree of recovery in ENDO-denuded vessels was 91.9% compared with 89.5% in ENDO intact vessels. For pressure jumps 60 to 100 mmHg, extent of recovery was 87.4 and 89.6%. During application of pressure ramps of 20 or 40 mmHg, vessel diameter did not increase by greater than 5%. There are no significant differences in these data, and we conclude that myogenic response in rabbit ear artery is mediated independently of endothelial-derived factors, irrespective of whether myogenic activation is induced by pressure jumps or ramps.
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Affiliation(s)
- R D MacPherson
- Department of Physiology, University of Tasmania, Hobart, Australia
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