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Capeding TPJ, Rosa JD, Lam H, Gaviola DG, Garfin AMC, Hontiveros C, Cunnama L, Laurence YV, Kitson N, Vassall A, Sweeney S, Garcia-Baena I. Cost of TB prevention and treatment in the Philippines in 2017. Int J Tuberc Lung Dis 2022; 26:392-398. [PMID: 35505478 PMCID: PMC9067429 DOI: 10.5588/ijtld.21.0622] [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] [Indexed: 01/13/2023] Open
Abstract
BACKGROUND: The Philippines aims to accelerate TB reduction through the provision of universally accessible and affordable services. The objectives of this paper are to estimate the costs of TB services and interventions using a health systems´ perspective, and to explore cost differences in service delivery via primary care facilities or hospitals.METHODS: Data were collected from a multi-stage stratified random sampling of 28 facilities in accordance with Global Health Cost Consortium costing standards and analysis tools. Unit costs (in US$) estimated using top-down (TD) and bottom-up (BU) approaches, are summarised following Value TB reporting standards and by broad facility type.RESULTS: Cost of delivering 32 TB services and eight interventions varied by costing method and delivery platform. Average BU costs ranged from US$0.38 for treatment support visits, US$2.5 for BCG vaccination, US$19.48 for the Xpert® MTB/RIF test to US$3,677 for MDR-TB treatment using the long regimen. Delivering TB care in hospitals was generally more costly than in primary care facilities, except for TB prevention in children and MDR-TB treatment using the long regimen.CONCLUSION: Comprehensive costing data for TB care in the Philippines are now available to aid in the design, planning, and prioritisation of delivery models to End TB.
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Affiliation(s)
- T. P. J. Capeding
- Institute of Health Policy and Development Studies, National Institutes of Health, University of the Philippines Manila, Manila, Philippines
| | - J. D. Rosa
- Institute of Health Policy and Development Studies, National Institutes of Health, University of the Philippines Manila, Manila, Philippines
| | - H. Lam
- Institute of Health Policy and Development Studies, National Institutes of Health, University of the Philippines Manila, Manila, Philippines
| | - D. G. Gaviola
- Department of Health, National TB Control Programme, Manila, Philippines
| | - A. M. C. Garfin
- Department of Health, National TB Control Programme, Manila, Philippines
| | - C. Hontiveros
- Department of Health, National TB Control Programme, Manila, Philippines
| | - L. Cunnama
- Health Economics Unit & Health Economics Division, University of Cape Town, Cape Town, South Africa
| | - Y. V. Laurence
- Department of Global Health and Development, Centre for Health Economics in London, London School of Hygiene & Tropical Medicine, London, UK
| | - N. Kitson
- Department of Global Health and Development, Centre for Health Economics in London, London School of Hygiene & Tropical Medicine, London, UK
| | - A. Vassall
- Department of Global Health and Development, Centre for Health Economics in London, London School of Hygiene & Tropical Medicine, London, UK
| | - S. Sweeney
- Department of Global Health and Development, Centre for Health Economics in London, London School of Hygiene & Tropical Medicine, London, UK
| | - I. Garcia-Baena
- Global TB Programme, World Health Organization, Geneva, Switzerland
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Chikovani I, Shengelia N, Marjanishvili N, Gabunia T, Khonelidze I, Cunnama L, Garcia Baena I, Kitson N, Sweeney S, Vassall A, Laurence YV. Cost of TB services in the public and private sectors in Georgia (No 2). Int J Tuberc Lung Dis 2021; 25:1019-1027. [PMID: 34886933 PMCID: PMC8675873 DOI: 10.5588/ijtld.21.0176] [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] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND: Patient-centred care along with optimal financing of inpatient and outpatient services are the main priorities of the Georgia National TB Programme (NTP). This paper presents TB diagnostics and treatment unit cost, their comparison with NTP tariffs and how the study findings informed TB financing policy.METHODS: Top-down (TD) and bottom-up (BU) mean unit costs for TB interventions by episode of care were calculated. TD costs were compared with NTP tariffs, and variations in these and the unit costs cost composition between public and private facilities was assessed.RESULTS: Outpatient interventions costs exceeded NTP tariffs. Unit costs in private facilities were higher compared with public providers. There was very little difference between per-day costs for drug-susceptible treatment and NTP tariffs in case of inpatient services. Treatment day financing exceeded actual costs in the capital (public facility) for drug-resistant TB, and this was lower in the regions.CONCLUSION: Use of reliable unit costs for TB services at policy discussions led to a shift from per-day payment to a diagnosis-related group model in TB inpatient financing in 2020. A next step will be informing policy decisions on outpatient TB care financing to reduce the existing gap between funding and costs.
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Affiliation(s)
- I Chikovani
- Curatio International Foundation, Tbilisi, Georgia
| | - N Shengelia
- Curatio International Foundation, Tbilisi, Georgia
| | | | - T Gabunia
- Ministry of Internally Displaced Persons from the Occupied Territories, Labour, Health and Social Affairs, Tbilisi, Georgia
| | - I Khonelidze
- National Center for Disease Control and Public Health, Tbilisi, Georgia
| | - L Cunnama
- Health Economics Unit & Health Economics Division, School of Public Health and Family Medicine, University of Cape Town, Cape Town, South Africa
| | - I Garcia Baena
- TB Monitoring and Evaluation, Global TB Programme, World Health Organization, Geneva, Switzerland
| | - N Kitson
- Centre for Health Economics in London, Department of Global Health and Development, London School of Hygiene & Tropical Medicine, London, UK
| | - S Sweeney
- Centre for Health Economics in London, Department of Global Health and Development, London School of Hygiene & Tropical Medicine, London, UK
| | - A Vassall
- Centre for Health Economics in London, Department of Global Health and Development, London School of Hygiene & Tropical Medicine, London, UK
| | - Y V Laurence
- Centre for Health Economics in London, Department of Global Health and Development, London School of Hygiene & Tropical Medicine, London, UK
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Kairu A, Orangi S, Oyando R, Kabia E, Nguhiu P, Ong Ang O J, Mwirigi N, Laurence YV, Kitson N, Garcia Baena I, Vassall A, Barasa E, Sweeney S, Cunnama L. Cost of TB services in healthcare facilities in Kenya (No 3). Int J Tuberc Lung Dis 2021; 25:1028-1034. [PMID: 34886934 PMCID: PMC8675875 DOI: 10.5588/ijtld.21.0129] [Citation(s) in RCA: 6] [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: 03/01/2021] [Accepted: 06/08/2021] [Indexed: 11/25/2022] Open
Abstract
BACKGROUND: The reduction of Kenya´s TB burden requires improving resource allocation both to and within the National TB, Leprosy and Lung Disease Program (NTLD-P). We aimed to estimate the unit costs of TB services for budgeting by NTLD-P, and allocative efficiency analyses for future National Strategic Plan (NSP) costing.METHODS: We estimated costs of all TB interventions in a sample of 20 public and private health facilities from eight counties. We calculated national-level unit costs from a health provider´s perspective using bottom-up (BU) and top-down (TD) approaches for the financial year 2017-2018 using Microsoft Excel and STATA v16.RESULTS: The mean unit cost for passive case-finding (PCF) was respectively US$38 and US$60 using the BU and TD approaches. The unit BU and TD costs of a 6-month first-line treatment (FLT) course, including monitoring tests, was respectively US$135 and US$160, while those for adult drug-resistant TB (DR-TB) treatment was respectively US$3,230.28 and US$3,926.52 for the 9-month short regimen. Intervention costs highlighted variations between BU and TD approaches. Overall, TD costs were higher than BU, as these are able to capture more costs due to inefficiency (breaks/downtime/leave).CONCLUSION: The activity-based TB unit costs form a comprehensive cost database, and the costing process has built-in capacity within the NTLD-P and international TB research networks, which will inform future TB budgeting processes.
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Affiliation(s)
- A Kairu
- Health Economics Research Unit, KEMRI-Wellcome Trust Research Programme, Nairobi, Kenya
| | - S Orangi
- Health Economics Research Unit, KEMRI-Wellcome Trust Research Programme, Nairobi, Kenya
| | - R Oyando
- Health Economics Research Unit, KEMRI-Wellcome Trust Research Programme, Nairobi, Kenya
| | - E Kabia
- Health Economics Research Unit, KEMRI-Wellcome Trust Research Programme, Nairobi, Kenya
| | - P Nguhiu
- Health Economics Research Unit, KEMRI-Wellcome Trust Research Programme, Nairobi, Kenya
| | - J Ong Ang O
- Centre for Respiratory Diseases Research, Kenya Medical Research Institute, Nairobi, Kenya
| | - N Mwirigi
- Ministry of Health, Division of National Tuberculosis, Leprosy, and Lung Disease Program, Nairobi, Kenya
| | - Y V Laurence
- Department of Global Health and Development, Faculty of Public Health and Policy, Centre for Health Economics in London, London School of Hygiene & Tropical Medicine, London, UK
| | - N Kitson
- Department of Global Health and Development, Faculty of Public Health and Policy, Centre for Health Economics in London, London School of Hygiene & Tropical Medicine, London, UK
| | - I Garcia Baena
- TB Monitoring and Evaluation, Global Tuberculosis Programme, World Health Organization, Geneva, Switzerland
| | - A Vassall
- Department of Global Health and Development, Faculty of Public Health and Policy, Centre for Health Economics in London, London School of Hygiene & Tropical Medicine, London, UK
| | - E Barasa
- Health Economics Research Unit, KEMRI-Wellcome Trust Research Programme, Nairobi, Kenya, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - S Sweeney
- Department of Global Health and Development, Faculty of Public Health and Policy, Centre for Health Economics in London, London School of Hygiene & Tropical Medicine, London, UK
| | - L Cunnama
- Health Economics Unit and Division, School of Public Health and Family Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
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Chatterjee S, Toshniwal MN, Bhide P, Sachdeva KS, Rao R, Laurence YV, Kitson N, Cunnama L, Vassall A, Sweeney S, Baena IG. Costs of TB services in India (No 1). Int J Tuberc Lung Dis 2021; 25:1013-1018. [PMID: 34886932 PMCID: PMC8675874 DOI: 10.5588/ijtld.21.0105] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [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] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND: There is a dearth of economic analysis required to support increased investment in TB in India. This study estimates the costs of TB services from a health systems’ perspective to facilitate the efficient allocation of resources by India’s National Tuberculosis Elimination Programme. METHODS: Data were collected from a multi-stage, stratified random sample of 20 facilities delivering TB services in two purposively selected states in India as per Global Health Cost Consortium standards and using Value TB Data Collection Tool. Unit costs were estimated using the top-down (TD) and bottom-up (BU) methodology and are reported in 2018 US dollars. RESULTS: Cost of delivering 50 types of TB services and four interventions varied according to costing method. Key services included sputum smear microscopy, Xpert® MTB/RIF and X-ray with an average BU costs of respectively US$2.45, US$17.36 and US$2.85. Average BU cost for bacille Calmette-Guérin vaccination, passive case-finding, TB prevention in children under 5 years using isoniazid and first-line drug treatment in new pulmonary and extrapulmonary TB cases was respectively US$0.76, US$1.62, US$2.41, US$103 and US$98. CONCLUSION: The unit cost of TB services and outputs are now available to support investment decisions, as diagnosis algorithms are reviewed and prevention or treatment for TB are expanded or updated in India.
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Affiliation(s)
- S Chatterjee
- George Institute for Global Health, New Delhi, India, University of New South Wales, Sydney, NSW, Australia, Manipal Academy of Higher Education, Manipal, India
| | - M N Toshniwal
- Independent consultant, Public Health Division, Durga Clinic, Akola, India
| | - P Bhide
- George Institute for Global Health, New Delhi, India
| | - K S Sachdeva
- Central TB Division, Ministry of Health and Family Welfare, Government of India, New Delhi, India
| | - R Rao
- Central TB Division, Ministry of Health and Family Welfare, Government of India, New Delhi, India
| | - Y V Laurence
- Department of Global Health and Development, Centre for Health Economics in London, London School of Hygiene & Tropical Medicine, London, UK
| | - N Kitson
- Department of Global Health and Development, Centre for Health Economics in London, London School of Hygiene & Tropical Medicine, London, UK
| | - L Cunnama
- Health Economics Unit & Health Economics Division, University of Cape Town, Cape Town, South Africa
| | - A Vassall
- Department of Global Health and Development, Centre for Health Economics in London, London School of Hygiene & Tropical Medicine, London, UK
| | - S Sweeney
- Department of Global Health and Development, Centre for Health Economics in London, London School of Hygiene & Tropical Medicine, London, UK
| | - I Garcia Baena
- Global TB Programme, World Health Organization, Geneva, Switzerland
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5
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Liu C, Kitson N. University of British Columbia Rural and Remote Dermatology Telemedicine Service: A Case of Porphyria Cutanea Tarda. J Cutan Med Surg 2021; 26:437. [PMID: 34496670 DOI: 10.1177/12034754211045392] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Affiliation(s)
- Chaocheng Liu
- 8166 Department of Dermatology and Skin Science, University of British Colombia, Vancouver, BC, Canada
| | - Neil Kitson
- 8166 Department of Dermatology and Skin Science, University of British Colombia, Vancouver, BC, Canada
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6
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Copley M, Guo D, Phan N, Pawlovich J, Kitson N. 368 Teledermatology and text messaging in rural and remote British Columbia: A survey of primary care providers. J Invest Dermatol 2018. [DOI: 10.1016/j.jid.2018.03.374] [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] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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7
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Guo D, Phan N, Ho K, Pawlovich J, Kitson N. Clinical Texting Among Medical Trainees of the University of British Columbia [Formula: see text]. J Cutan Med Surg 2018; 22:384-389. [PMID: 29411629 DOI: 10.1177/1203475418758292] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
We believe cellphone text messages are commonly used in medical practice whether in rural or urban settings and that clinical photos are often attached to them. Our interest is the use of this technology to provide dermatology service to rural and remote British Columbia. Concern has been expressed about the security of confidential information and adequacy of privacy protection in such an application. We have found little published information about the extent of texting in rural and remote settings (and none in our jurisdiction) or the number and nature of privacy breaches that have actually occurred as a result. To obtain such information, we first set out to survey medical practitioners about their actual use. The results reported here are from medical trainees enrolled with the University of British Columbia who are in both rural and urban settings.
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Affiliation(s)
- Danny Guo
- 1 Department of Dermatology and Skin Science, University of British Columbia, Vancouver, BC, Canada
| | - Nam Phan
- 2 Department of Family Practice, University of British Columbia, Vancouver, BC, Canada
| | - Kendall Ho
- 3 Department of Emergency Medicine, University of British Columbia, Vancouver, BC, Canada
| | - John Pawlovich
- 2 Department of Family Practice, University of British Columbia, Vancouver, BC, Canada.,4 Rural Education Action Plan, Doctors of BC, Vancouver, BC, Canada and British Columbia Ministry of Health, Victoria, BC Canada
| | - Neil Kitson
- 5 Department of Dermatology and Skin Science, University of British Columbia, Vancouver, BC, Canada
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8
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Siriwardena M, Campbell V, Kitson N, Yandle T, Richards M, Pemberton C. BNP Signal Peptide and High Sensitivity Troponin T Response During Dobutamine Stress Echocardiography. Heart Lung Circ 2011. [DOI: 10.1016/j.hlc.2011.05.067] [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] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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9
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Laule C, Tahir S, Chia CLL, Vavasour IM, Kitson N, MacKay AL. A proton NMR study on the hydration of normal versus psoriatic stratum corneum: linking distinguishable reservoirs to anatomical structures. NMR Biomed 2010; 23:1181-1190. [PMID: 20665901 DOI: 10.1002/nbm.1547] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
The NMR behaviour of normal and psoriatic stratum corneum (SC) was investigated as a function of hydration with the aim of obtaining a better understanding of the role of water in the SC structure. Time domain NMR techniques were employed to identify the signal from water and that from nonaqueous components of the SC, such as lipids and proteins. The signals were investigated as a function of water content. The free induction decay was separated into mobile signal (from water and mobile lipids) and solid signal (from protein and 'solid' lipids). Spin-spin relaxation (T(2)) measurements further separated the mobile domains within the SC. The results suggested that, when water is added to dry SC, it first enters the corneocytes; then, at a hydration of 0.24-0.33 g H(2)O/g SC (normal SC) or 0.12-0.24 g H(2)O/g SC (psoriatic SC), water begins to accumulate in hydrated lipid regions. Water was found to exchange between these two domains on the time scale of a few hundred milliseconds. When compared with normal SC, psoriatic SC had a looser corneocyte structure, a larger mobile lipid component at low hydration and a smaller capacity for corneocyte water.
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Affiliation(s)
- Cornelia Laule
- Department of Physics and Astronomy, University of British Columbia, Vancouver, BC, Canada.
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10
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Brief E, Kwak S, Cheng JTJ, Kitson N, Thewalt J, Lafleur M. Phase behavior of an equimolar mixture of N-palmitoyl-D-erythro-sphingosine, cholesterol, and palmitic acid, a mixture with optimized hydrophobic matching. Langmuir 2009; 25:7523-7532. [PMID: 19563230 DOI: 10.1021/la9003643] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The phase behavior and lipid mixing properties of an equimolar mixture of nonhydroxylated palmitoyl ceramide (Cer16), palmitic acid (PA), and cholesterol have been investigated using 2H NMR and vibrational spectroscopy. This mixture is formed by the three main classes of lipids found in the stratum corneum (SC), the top layer of the epidermis, and provides an optimized hydrophobic matching. Therefore, its behavior highlights the role played by hydrophobic matching on the phase behavior of SC lipids. We found that, below 45 degrees C, the mixture is essentially formed of coexisting crystalline domains with a small fraction of lipids (less than 20%) that forms a gel or fluid phase, likely ensuring cohesion between the solid domains. Upon heating, there is the formation of a liquid ordered phase mainly composed of PA and cholesterol, including a small fraction of Cer16. This finding is particularly highlighted by correlation vibrational microspectroscopy that indicates that domains enriched in cholesterol and PA include more disordered Cer16 than those found in the Cer16-rich domains. Solubilization of Cer16 in the fluid phase occurs progressively upon further heating, and this leads to the formation of a nonlamellar self-assembly where the motions are isotropic on the NMR time scale. It is found that the miscibility of Cer16 with cholesterol and PA is more limited than the one previously observed for ceramide III extracted from bovine brain, which is heterogeneous in chain composition and includes, in addition to Cer16, analogous ceramide with longer alkyl chains that are not hydrophobically matched with cholesterol and PA. Therefore, it is inferred that, in SC, the chain heterogeneity is a stronger criteria for lipid miscibility than chain hydrophobic matching.
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Affiliation(s)
- Elana Brief
- Department of Physics, Simon Fraser University, Burnaby, British Columbia, Canada
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11
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Buchan JC, Ashiq A, Kitson N, Dixon J, Cassels-Brown A, Bradbury JA. Nurse specialist treatment of eye emergencies: five year follow up study of quality and effectiveness. Int Emerg Nurs 2009; 17:149-54. [PMID: 19577201 DOI: 10.1016/j.ienj.2008.12.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2008] [Revised: 10/30/2008] [Accepted: 12/04/2008] [Indexed: 11/28/2022]
Abstract
The role of specialist nurses in triage, diagnosis and management of emergency eye conditions is well established, and encouraging reports of the safety and effectiveness of such services have been published. Specialist nurses in an emergency eye clinic in the UK seeing >7000 patients per year had been found at initial evaluation to treat 22% of the 1976 patients seen over a three month period without referring on to an ophthalmologist. A repeat of this evaluation five years later found this proportion had dropped to 17% (chi(2) = 16.7, p<0.01). In addition, the initial evaluation had found no incident of any patient having been treated and discharged by the specialist nurses returning to the department due to incorrect diagnosis or mismanagement. By contrast, from the sample 5 years later, 3 patients were identified who returned to the department due to possible misdiagnosis or sub-optimal management. We suggest that provision must be made for continuing professional development of nurses in this type of extended role, and the commitment to ongoing education should be backed up by a system of monitoring and critical incident reporting to facilitate skill maintenance and the life long learning process for specialist nurses.
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Affiliation(s)
- John Cameron Buchan
- Department of Ophthalmology, St. James's University Hospital, Beckett Street, Leeds LS9 7TF, United Kingdom.
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12
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Chen X, Kwak S, Lafleur M, Bloom M, Kitson N, Thewalt J. Fatty acids influence "solid" phase formation in models of stratum corneum intercellular membranes. Langmuir 2007; 23:5548-56. [PMID: 17402763 DOI: 10.1021/la063640+] [Citation(s) in RCA: 32] [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] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Stacked intercellular lipid membranes in the uppermost epidermal layer, the stratum corneum (SC), are responsible for skin's barrier function. These membranes are unique in composition, the major lipids being ceramides (Cer), cholesterol, and free fatty acids (FFA) in approximately equimolar proportions. Notably, SC lipids include chains much longer than those of most biological membranes. Previously we showed that Cer's small hydrophilic headgroup enabled SC model membranes composed of bovine brain ceramide (BBCer), cholesterol, and palmitic acid in equimolar proportion to solidify at pH 5.2. In order to determine the influence of FFA chain length on the phase behavior of such membranes, we used 2H NMR and FT-IR to study BBCer/cholesterol/FFA dispersions containing linear saturated FFA 14-22 carbons long. Independent of chain length, the solid phase dominated the FFA spectrum at physiological temperature. Upon heating, each dispersion underwent phase transitions to a liquid crystalline phase (only weakly evident for the membrane containing FFA-C22) and then to an isotropic phase. The phase behavior, the lipid mixing properties, and the transition temperatures are shown to depend strongly on FFA chain length. A distribution of FFA chain lengths is found in the SC and could be required for the coexistence of a proportion of solid lipids with some more fluid domains, which is known to be necessary for normal skin barrier function.
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Affiliation(s)
- Xin Chen
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z1
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13
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Rowat AC, Kitson N, Thewalt JL. Interactions of oleic acid and model stratum corneum membranes as seen by 2H NMR. Int J Pharm 2005; 307:225-31. [PMID: 16293379 DOI: 10.1016/j.ijpharm.2005.10.008] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2005] [Revised: 10/05/2005] [Accepted: 10/05/2005] [Indexed: 11/23/2022]
Abstract
We have investigated the mechanism through which the penetration enhancer oleic acid acts on stratum corneum (SC) model membranes (bovine brain ceramide:cholesterol:palmitic acid, 1:1:1 molar ratio). We used solid state deuterium nuclear magnetic resonance to monitor such multilamellar SC dispersions containing either cholesterol-d(6), palmitic acid-d(31), or oleic acid-d(2) as a function of both fatty acid concentration (2:2:1:1 and 1:1:1:1 bovine brain ceramide:cholesterol:palmitic acid:oleic acid) and temperature (18-75 degrees C). Our results show that below 40 degrees C, oleic acid (OA) is in an 'isotropic' phase, indicating that it has not incorporated into the lamellar membrane phase. At and above the SC model membrane's crystalline to liquid crystalline melting temperature, T(m)=40-42 degrees C, OA interacts with lamellar SC membranes with a slight dependence on OA concentration. T(m) does not change upon the exposure of the SC model membrane to OA, nor do we see any significant change in membrane chain disorder as monitored by the labelled PA. However, the spectra of both the palmitic acid (PA) and cholesterol SC model membrane components contain an isotropic peak that grows with increasing temperature. Our results thus indicate that oleic acid extracts a fraction of the endogenous SC membrane components, promoting phase separation in the SC membrane system. Reducing the proportion of crystalline lipids and creating more permeable OA-rich domains is a plausible mechanism that explains how OA enhances transdermal penetration.
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Affiliation(s)
- Amy C Rowat
- MEMPHYS, Department of Physics, University of Southern Denmark, Campusvej 55, 5230 Odense M, Denmark
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14
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Abstract
Biological membranes contain domains having distinct physical properties. We study defined mixtures of phosphoglycerolipids and sphingolipids to ascertain the fundamental interactions governing these lipids in the absence of other cell membrane components. By using (2)H-NMR we have determined the temperature and composition dependencies of membrane structure and phase behavior for aqueous dispersions of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) and the ceramide (Cer) N-palmitoyl-sphingosine. It is found that gel and liquid-crystalline phases coexist over a wide range of temperature and composition. Domains of different composition and phase state are present in POPC/Cer membranes at physiological temperature for Cer concentrations exceeding 15 mol %. The acyl chains of liquid crystalline phase POPC are ordered by the presence of Cer. Moreover, Cer's chain ordering is greater than that of POPC in the liquid crystalline phase. However, there is no evidence of liquid-liquid phase separation in the liquid crystalline region of the POPC/Cer phase diagram.
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Affiliation(s)
- Ya-Wei Hsueh
- Department of Physics, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada
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15
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Abstract
The stratum corneum is a complex biological material characterized by very low permeability to water and most other molecules. This material may be thought of as a 'porous medium' composed of impermeable and permeable regions. Intercellular lipid membranes in the stratum corneum are postulated to exist in a mixture of two phases: solid (i.e. impermeable) and liquid crystalline (permeable). The corneocyte envelope is classified as impermeable. Diffusion mechanisms of solutes within, across and between the intercellular lamellae are discussed. This model represents a refinement of previous theories about the physical structures responsible for the low observed permeability of the stratum corneum.
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Affiliation(s)
- N Kitson
- Dept. of Medicine, University of British Columbia, Vancouver, Canada.
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Vavasour I, Kitson N, MacKay A. What's water got to do with it? A nuclear magnetic resonance study of molecular motion in pig stratum corneum. J Investig Dermatol Symp Proc 1998; 3:101-4. [PMID: 9734821 DOI: 10.1038/jidsymp.1998.21] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [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: 04/11/2023]
Abstract
The 1H and 2H magnetic resonance signals from pig stratum corneum were measured as a function of hydration. The 1H free induction decay contained two components, one motionally restricted and the other isotropically mobile on the timescale of 10(-5) s. From its T2 decay, the mobile signal was further subdivided into two components; one, which was 11% of the signal and 5.5% of the mass of the dehydrated stratum corneum, was assigned to nonaqueous tissue (likely hydrocarbons) and the other to water. As water content increased from 0 to 0.25 gH2O/gSC, the second moment of the motionally restricted signal decreased from 5.4 x 10(9) to 3.6 x 10(9) s(-2), whereas the water T2 time increased from less than 0.3 ms to 3.3 ms. The 2H quadrupolar echo from stratum corneum hydrated in 2H2O had a signal from motionally restricted deuterons, attributed to deuterons exchanged onto O-H and N-H groups, and a mobile signal from 2H2O. The amount of exchange, 9.5% of the hydrogen sites in the motionally restricted fraction, was close to the number of exchangeable sites on keratin, the most abundant protein in stratum corneum. Our results are consistent with a model in which the bulk of the water interacts closely with the corneocytes in stratum corneum.
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Affiliation(s)
- I Vavasour
- Department of Physics and Astronomy, University of British Columbia, Vancouver, Canada
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17
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Abstract
The permeability of mammalian skin is determined in large part by lamellar lipid domains packed between cells of the upper layer of the epidermis, the stratum comeum. Although these lamellae have features in common with typical biological membranes, they differ in having a lipid population composed mainly of ceramides, cholesterol, and free fatty acids. In our initial studies of the relationship between lipid composition and phase behavior in this unusual system, we used deuterium NMR [Kitson et al. (1994) Biochemistry 33, 6707-6715] to examine aqueous dispersions of nonhydroxylated bovine brain ceramide, cholesterol, and perdeuterated palmitic acid, and found complex phase behavior as a function of temperature and pH, whereas analogous dispersions in which sphingomyelin replaced ceramide resulted in spectra consistent with a fluid lamellar phase under the same conditions. To extend these observations, we examined the same dispersions at pH 5.2 by means of X-ray diffraction. The significant findings are as follows: (1) the ceramide dispersions form complex crystalline phases between room temperature and about 40 degrees C; (2) the majority of the crystalline cholesterol is not in a separate phase; and (3) the analogous sphingomyelin dispersions form a fluid lamellar phase under the same conditions. We conclude that ceramides, even in the presence of considerable mole fractions of cholesterol, can form crystalline lamellar structures. We suggest that the existence of such structures in stratum corneum may be important in the function of the epidermal permeability barrier, and that the interaction between ceramide and cholesterol in other biological membranes may result in regions having unique physical properties.
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Affiliation(s)
- J A Bouwstra
- Leiden/Amsterdam Center for Drug Research, Gorlaeus Laboratories, Leiden University, The Netherlands
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Abstract
Positron emission tomography (PET) was used to identify the brain regions activated during the 'inner signing' of sentences in subjects who were profoundly deaf and normally communicated using sign language. Although this appeared to involve the internal representation of hand and arm movements in space, it activated the left inferior frontal cortex rather than visuo-spatial areas. The activated region corresponds to that engaged during the silent articulation of sentences in hearing subjects. This suggests that 'inner signing' is mediated by similar regions to inner speech, and is consistent with neuropsychological data implicating the left hemisphere in the generation of sign language.
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Affiliation(s)
- P K McGuire
- Department of Psychological Medicine, King's College School of Medicine, London, UK
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19
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Abstract
Deuterium NMR was used to characterize model membrane systems approximating the composition of the intercellular lipid lamellae of mammalian stratum corneum (SC). The SC models, equimolar mixtures of ceramide:cholesterol:palmitic acid (CER:CHOL:PA) at pH 5.2, were contrasted with the sphingomyelin:CHOL:PA (SPM:CHOL:PA) system, where the SPM differs from the CER only in the presence of a phosphocholine headgroup. The lipids were prepared both as oriented samples and as multilamellar dispersions, and contained either perdeuterated palmitic acid (PA-d31) or [2,2,3,4,6-2H5]CHOL (CHOL-d5). SPM:CHOL:PA-d31 formed liquid-ordered membranes over a wide range of temperatures, with a maximum order parameter of approximately 0.4 at 50 degrees C for positions C3-C10 (the plateau region). The quadrupolar splitting at C2 was significantly smaller, suggesting an orientational change at this position, possibly because of hydrogen bonding with water and/or other surface components. A comparison of the longitudinal relaxation times obtained at theta = 0 degrees and 90 degrees (where theta is the angle between the normal to the glass plates and the magnetic field) revealed a significant T1Z anisotropy for all positions. In contrast to the behavior observed with the SPM system, lipid mixtures containing CER exhibited a complex polymorphism. Between 20 and 50 degrees C, a significant portion of the entire membrane (as monitored by both PA-d31 and CHOL-d5) was found to exist as a solid phase, with the remainder either a gel or liquid-ordered phase. The proportion of solid decreased as the temperature was increased and disappeared entirely above 50 degrees C. Between 50 and 70 degrees C, the membrane underwent a liquid-ordered to isotropic phase transition. These transitions were reversible but displayed considerable hysteresis, especially the conversion from a fluid phase to solid. The order profiles, relaxation behavior, and angular dependence of these parameters suggest strongly that both the liquid-ordered CER- and SPM-membranes are bilayers. The unusual phase behavior observed for the CER-system, particularly the observation of solid-phase lipid at physiological temperatures, may provide insight into the functioning of the permeability barrier of stratum corneum.
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Affiliation(s)
- D B Fenske
- Department of Biochemistry, Faculty of Medicine, University of British Columbia, Vancouver, Canada
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20
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Abstract
Psychiatric screening questionnaires for deaf children and adolescents were piloted in a group of 62 children, aged 11-16 years, attending a residential school. The questionnaires, Parent's Checklist (PCL) and Teacher's Checklist (TCL) were then used to screen a group of 93 children attending one Deaf School and three Hearing Impaired Units (HIU). Psychiatric assessments were conducted with a highly structured diagnostic interview, the Child Assessment Schedule (CAS). The interview with signing deaf children was conducted with a sign language interpreter. The prevalence of psychiatric disorder in the whole group was 50.3%, 42.4% in the group attending the Deaf School and 60.9% for the group attending the HIUs. An aetiological model of psychiatric disorder in this group is proposed.
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Affiliation(s)
- P A Hindley
- Department of Mental Health Sciences, St George's Hospital Medical School, London, U.K
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21
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Abstract
The permeability barrier of mammalian skin is found in unusual intercellular domains in the upper layers of the epidermis, and is composed mainly of three lipid classes: ceramide, cholesterol, and free fatty acid. These are organized as lamellae, but the details of lipid organization are not precisely known. To examine the relationship between lipid composition and phase behavior, aqueous dispersions of bovine brain ceramide, cholesterol, and perdeuterated palmitic acid were examined by 2H NMR and compared to analogous systems in which sphingomyelin replaced ceramide. The sphingomyelin systems give rise as expected to a stable fluid lamellar signal over the temperature range 20-75 degrees C and pH 5.2-7.4, whereas the ceramide dispersions show complex polymorphism as a function of both temperature and pH. Prominent features of the ceramide dispersions containing cholesterol are phase coexistence and the presence of a "solid" phase in which molecular motion is more inhibited than in a classical phospholipid gel phase: T1z measurements indicate that lateral diffusion of the palmitic acid probe effectively does not occur. In the absence of cholesterol, a fluid lamellar signal is not observed, but the appearance of a "solid" signal is also influenced by the pH. In the presence of cholesterol, a fluid lamellar signal is present at 50 degrees C, and the 2H NMR order parameter profile is very similar to that derived from the analogous sphingomyelin dispersions.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- N Kitson
- Division of Dermatology, University of British Columbia, Vancouver, Canada
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Thewalt J, Kitson N, Araujo C, MacKay A, Bloom M. Models of stratum corneum intercellular membranes: the sphingolipid headgroup is a determinant of phase behavior in mixed lipid dispersions. Biochem Biophys Res Commun 1992; 188:1247-52. [PMID: 1445357 DOI: 10.1016/0006-291x(92)91365-w] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.4] [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
During formation of the intercellular membranes of mammalian stratum corneum, sphingomyelin and glucosylceramide are converted enzymatically to ceramide. To model in isolation the possible effect of such a lipid modification on the phase behavior of the ensemble, we used proton and deuterium nuclear magnetic resonance to compare an equimolar dispersion of bovine brain sphingomyelin, cholesterol, and perdeuterated palmitic acid (at pH 6.2), with an equivalent dispersion in which bovine brain ceramide was substituted for sphingomyelin. While the sphingomyelin dispersions remain in a homogeneous fluid lamellar phase from 20-75 degrees C under these conditions, those containing ceramide display complex polymorphism.
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Affiliation(s)
- J Thewalt
- Dept. of Physics, University of British Columbia, Vancouver, Canada
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Kitson N, Monck M, Wong K, Thewalt J, Cullis P. The influence of cholesterol 3-sulphate on phase behaviour and hydrocarbon order in model membrane systems. Biochim Biophys Acta 1992; 1111:127-33. [PMID: 1390858 DOI: 10.1016/0005-2736(92)90282-q] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Cholesterol 3-sulphate (CS) is a component of the intercellular lipid found in the uppermost layer of human epidermis (the 'stratum corneum') and is thought to play an important role in tissue cohesion. In this investigation we have compared the influence of cholesterol (CH) and CS on the gel-to-liquid crystalline phase behaviour, the polymorphic phase behaviour, and the hydrocarbon order profile in selected model membranes. It is shown that in sphingomyelin (SPM) systems, the presence of equimolar amounts of either CH or CS eliminates the gel-to-liquid crystalline transition as detected by calorimetry. Similarly, in 1-palmitoyl,2-oleoyl-phosphatidylethanolamine (POPE) dispersions containing a perdeuterated palmitoyl chain (POPE-d31), it is shown that both CH and CS exert an ordering effect as determined by 2H-NMR techniques, however, CS is less potent at temperatures both above and below that of the main transition for the native phospholipid. Alternatively, in mixed systems containing dioleoylphosphatidylethanolamine (DOPE) and SPM (DOPE/SPM, 6:1 mol/mol) CH promotes thermotropic L alpha-->HII phase transitions, whereas CS stabilizes the bilayer organization. These bilayer stabilization effects can be diminished by addition of Ca2+. These effects are consistent with a larger area per molecule of CS as compared to CH, presumably related to the presence of the negatively charged sulphate moiety of CS.
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Affiliation(s)
- N Kitson
- Department of Medicine, University of British Columbia, Vancouver, Canada
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Kitson N, Fry R. Prelingual deafness and psychiatry. Br J Hosp Med (Lond) 1990; 44:353-6. [PMID: 2276003] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
This article provides an introduction to the neglected area of psychiatry and prelingual deafness. 'Deafness' refers to prelingual profound deafness except where indicated, although many of the observations apply to some extent to prelingually partially hearing people.
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Affiliation(s)
- N Kitson
- Supra Regional Mental Health Service for Deaf People, Springfield Hospital, London
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Abstract
Human sebaceous glands were studied by electron microscopy using lanthanum tracer and freeze-fracture methods. Gap junctions but no tight junctions were found. It is suggested that the essential permeability barrier may be formed by the secreted sebaceous neutral lipid.
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Abstract
An examination of human seabaceous glands by transmission electron microscopy has revealed the presence of gap junctions. The junctions are found in abundance between differentiating cells, and annular forms are also seen. The possible significance of this new finding is briefly discussed.
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