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Haskell A, White BP, Rogers RE, Goebel E, Lopez MG, Syvyk AE, de Oliveira DA, Barreda HA, Benton J, Benavides OR, Dalal S, Bae E, Zhang Y, Maitland K, Nikolov Z, Liu F, Lee RH, Kaunas R, Gregory CA. Scalable manufacture of therapeutic mesenchymal stromal cell products on customizable microcarriers in vertical wheel bioreactors that improve direct visualization, product harvest, and cost. Cytotherapy 2024; 26:372-382. [PMID: 38363250 DOI: 10.1016/j.jcyt.2024.01.009] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2023] [Revised: 01/23/2024] [Accepted: 01/27/2024] [Indexed: 02/17/2024]
Abstract
BACKGROUND AIMS Human mesenchymal stromal cells (hMSCs) and their secreted products show great promise for treatment of musculoskeletal injury and inflammatory or immune diseases. However, the path to clinical utilization is hampered by donor-tissue variation and the inability to manufacture clinically relevant yields of cells or their products in a cost-effective manner. Previously we described a method to produce chemically and mechanically customizable gelatin methacryloyl (GelMA) microcarriers for culture of hMSCs. Herein, we demonstrate scalable GelMA microcarrier-mediated expansion of induced pluripotent stem cell (iPSC)-derived hMSCs (ihMSCs) in 500 mL and 3L vertical wheel bioreactors, offering several advantages over conventional microcarrier and monolayer-based expansion strategies. METHODS Human mesenchymal stromal cells derived from induced pluripotent cells were cultured on custom-made spherical gelatin methacryloyl microcarriers in single-use vertical wheel bioreactors (PBS Biotech). Cell-laden microcarriers were visualized using confocal microscopy and elastic light scattering methodologies. Cells were assayed for viability and differentiation potential in vitro by standard methods. Osteogenic cell matrix derived from cells was tested in vitro for osteogenic healing using a rodent calvarial defect assay. Immune modulation was assayed with an in vivo peritonitis model using Zymozan A. RESULTS The optical properties of GelMA microcarriers permit noninvasive visualization of cells with elastic light scattering modalities, and harvest of product is streamlined by microcarrier digestion. At volumes above 500 mL, the process is significantly more cost-effective than monolayer culture. Osteogenic cell matrix derived from ihMSCs expanded on GelMA microcarriers exhibited enhanced in vivo bone regenerative capacity when compared to bone morphogenic protein 2, and the ihMSCs exhibited superior immunosuppressive properties in vivo when compared to monolayer-generated ihMSCs. CONCLUSIONS These results indicate that the cell expansion strategy described here represents a superior approach for efficient generation, monitoring and harvest of therapeutic MSCs and their products.
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Affiliation(s)
- Andrew Haskell
- Department of Cell Biology and Genetics, Texas A&M School of Medicine, Bryan, Texas, USA
| | - Berkley P White
- Department of Biomedical Engineering, Texas A&M University, College Station, Texas, USA
| | - Robert E Rogers
- Department of Cell Biology and Genetics, Texas A&M School of Medicine, Bryan, Texas, USA
| | - Erin Goebel
- Department of Cell Biology and Genetics, Texas A&M School of Medicine, Bryan, Texas, USA; Department of Biomedical Engineering, Texas A&M University, College Station, Texas, USA
| | - Megan G Lopez
- Department of Cell Biology and Genetics, Texas A&M School of Medicine, Bryan, Texas, USA
| | - Andrew E Syvyk
- National Center for Therapeutics Manufacturing, Texas A&M University, College Station, Texas, USA
| | - Daniela A de Oliveira
- National Center for Therapeutics Manufacturing, Texas A&M University, College Station, Texas, USA; Biological and Agricultural Engineering, Texas A&M University, College Station, Texas, USA
| | - Heather A Barreda
- Department of Cell Biology and Genetics, Texas A&M School of Medicine, Bryan, Texas, USA
| | - Joshua Benton
- Department of Cell Biology and Genetics, Texas A&M School of Medicine, Bryan, Texas, USA
| | - Oscar R Benavides
- Department of Biomedical Engineering, Texas A&M University, College Station, Texas, USA
| | - Sujata Dalal
- Department of Cell Biology and Genetics, Texas A&M School of Medicine, Bryan, Texas, USA
| | - EunHye Bae
- Department of Cell Biology and Genetics, Texas A&M School of Medicine, Bryan, Texas, USA
| | - Yu Zhang
- Department of Cell Biology and Genetics, Texas A&M School of Medicine, Bryan, Texas, USA
| | - Kristen Maitland
- Department of Biomedical Engineering, Texas A&M University, College Station, Texas, USA; Imaging Program, Chan Zuckerberg Initiative, Redwood City, California, USA
| | - Zivko Nikolov
- National Center for Therapeutics Manufacturing, Texas A&M University, College Station, Texas, USA; Biological and Agricultural Engineering, Texas A&M University, College Station, Texas, USA
| | - Fei Liu
- Department of Cell Biology and Genetics, Texas A&M School of Medicine, Bryan, Texas, USA
| | - Ryang Hwa Lee
- Department of Cell Biology and Genetics, Texas A&M School of Medicine, Bryan, Texas, USA
| | - Roland Kaunas
- Department of Biomedical Engineering, Texas A&M University, College Station, Texas, USA.
| | - Carl A Gregory
- Department of Cell Biology and Genetics, Texas A&M School of Medicine, Bryan, Texas, USA.
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Soliman C, Faircloth J, Tu D, Mabbott S, Maitland K, Coté G. Exploring the Clinical Utility of Raman Spectroscopy for Point-of-Care Cardiovascular Disease Biomarker Detection. Appl Spectrosc 2023; 77:1181-1193. [PMID: 37487187 DOI: 10.1177/00037028231187963] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/26/2023]
Abstract
A variety of innovative point-of-care (POC) solutions using Raman systems have been explored. However, the vast effort is in assay development, while studies of the characteristics required for Raman spectrometers to function in POC applications are lacking. In this study, we tested and compared the performance of eight commercial Raman spectrometers ranging in size from benchtop Raman microscopes to portable and handheld Raman spectrometers using paper fluidic cartridges, including their ability to detect cardiac troponin I and heart fatty acid binding protein, both of which are well-established biomarkers for evaluating cardiovascular health. Each spectrometer was evaluated in terms of excitation wavelength, laser characteristics, and ease of use to investigate POC utility. We found that the Raman spectrometers equipped with 780 and 785 nm laser sources exhibited a reduced background signal and provided higher sensitivity compared to those with 633 and 638 nm laser sources. Furthermore, the spectrometer equipped with the single acquisition line readout functionality showed improved performance when compared to the point scan spectrometers and allowed measurements to be made faster and easier. The portable and handheld spectrometers also showed similar detection sensitivity to the gold standard instrument. Lastly, we reduced the laser power for the spectrometer with single acquisition line readout capability to explore the system performance at a laser power that change the classification from a Class 3B laser device to a Class 3R device and found that it showed comparable performance. Overall, these findings show that portable Raman spectrometers have the potential to be used in POC settings with accuracy comparable to laboratory-grade instruments, are relatively low-cost, provide fast signal readout, are easy to use, and can facilitate access for underserved communities.
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Affiliation(s)
- Cyril Soliman
- Department of Biomedical Engineering, Texas A&M University, College Station, Texas, USA
| | | | - Dandan Tu
- Department of Biomedical Engineering, Texas A&M University, College Station, Texas, USA
| | - Samuel Mabbott
- Department of Biomedical Engineering, Texas A&M University, College Station, Texas, USA
- Texas A&M Engineering Experiment Station, Center for Remote Health Technologies and Systems, College Station, Texas, USA
| | - Kristen Maitland
- Department of Biomedical Engineering, Texas A&M University, College Station, Texas, USA
- Texas A&M Engineering Experiment Station, Center for Remote Health Technologies and Systems, College Station, Texas, USA
- Imaging Program, Chan Zuckerberg Initiative, Redwood City, California, USA
| | - Gerard Coté
- Department of Biomedical Engineering, Texas A&M University, College Station, Texas, USA
- Texas A&M Engineering Experiment Station, Center for Remote Health Technologies and Systems, College Station, Texas, USA
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Soliman C, Tu D, Mabbott S, Coté G, Maitland K. Portable, multi-modal Raman and fluorescence spectroscopic platform for point-of-care applications. J Biomed Opt 2022; 27:095006. [PMID: 36163635 PMCID: PMC9510839 DOI: 10.1117/1.jbo.27.9.095006] [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] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/08/2022] [Accepted: 09/09/2022] [Indexed: 06/16/2023]
Abstract
SIGNIFICANCE Point-of-care (POC) platforms utilizing optical biosensing strategies can achieve on-site detection of biomarkers to improve the quality of care for patients in low-resource settings. AIM We aimed to develop a portable, multi-modal spectroscopic platform capable of performing Raman and fluorescence measurements from a single sample site. APPROACH We designed the spectroscopic platform in OpticStudio using commercial optical components and built the system on a portable optical breadboard. Two excitation and collection arms were utilized to detect the two optical signals. The multi-modal functionality was validated using ratiometric Raman/fluorescence samples, and the potential utility was demonstrated using a model bioassay for cardiac troponin I. RESULTS The designed spectroscopic platform achieved a spectral resolution of 0.67 ± 0.2 nm across the Raman detection range (660 to 770 nm). The ratiometric Raman/fluorescence samples demonstrated no crosstalk between the two detector arms across a gradient of high molar concentrations. Testing of the model bioassay response showed that the integrated approach improved the linearity of the calibration curve from (R2 = 0.977) for the Raman only and (R2 = 0.972) for the fluorescence only to (R2 = 0.988) for the multi-modal approach. CONCLUSION These findings demonstrate the potential impact of a multi-modal POC spectroscopic platform to improve the sensitivity and robustness necessary for biomarker detection.
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Affiliation(s)
- Cyril Soliman
- Texas A&M University, Department of Biomedical Engineering, College Station, Texas, United States
| | - Dandan Tu
- Texas A&M University, Department of Biomedical Engineering, College Station, Texas, United States
| | - Samuel Mabbott
- Texas A&M University, Department of Biomedical Engineering, College Station, Texas, United States
- Texas A&M Engineering Experiment Station, Center for Remote Health Technologies and Systems, College Station, Texas, United States
| | - Gerard Coté
- Texas A&M University, Department of Biomedical Engineering, College Station, Texas, United States
- Texas A&M Engineering Experiment Station, Center for Remote Health Technologies and Systems, College Station, Texas, United States
| | - Kristen Maitland
- Texas A&M University, Department of Biomedical Engineering, College Station, Texas, United States
- Texas A&M Engineering Experiment Station, Center for Remote Health Technologies and Systems, College Station, Texas, United States
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Maitland K, Kiguli S, Olupot-Olupot P, Hamaluba M, Thomas K, Alaroker F, Opoka RO, Tagoola A, Bandika V, Mpoya A, Mnjella H, Nabawanuka E, Okiror W, Nakuya M, Aromut D, Engoru C, Oguda E, Williams TN, Fraser JF, Harrison DA, Rowan K. Randomised controlled trial of oxygen therapy and high-flow nasal therapy in African children with pneumonia. Intensive Care Med 2021; 47:566-576. [PMID: 33954839 PMCID: PMC8098782 DOI: 10.1007/s00134-021-06385-3] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Accepted: 03/15/2021] [Indexed: 12/27/2022]
Abstract
Purpose The life-saving role of oxygen therapy in African children with severe pneumonia is not yet established. Methods The open-label fractional-factorial COAST trial randomised eligible Ugandan and Kenyan children aged > 28 days with severe pneumonia and severe hypoxaemia stratum (SpO2 < 80%) to high-flow nasal therapy (HFNT) or low-flow oxygen (LFO: standard care) and hypoxaemia stratum (SpO2 80–91%) to HFNT or LFO (liberal strategies) or permissive hypoxaemia (ratio 1:1:2). Children with cyanotic heart disease, chronic lung disease or > 3 h receipt of oxygen were excluded. The primary endpoint was 48 h mortality; secondary endpoints included mortality or neurocognitive sequelae at 28 days. Results The trial was stopped early after enrolling 1852/4200 children, including 388 in the severe hypoxaemia stratum (median 7 months; median SpO2 75%) randomised to HFNT (n = 194) or LFO (n = 194) and 1454 in the hypoxaemia stratum (median 9 months; median SpO2 88%) randomised to HFNT (n = 363) vs LFO (n = 364) vs permissive hypoxaemia (n = 727). Per-protocol 15% of patients in the permissive hypoxaemia group received oxygen (when SpO2 < 80%). In the severe hypoxaemia stratum, 48-h mortality was 9.3% for HFNT vs. 13.4% for LFO groups. In the hypoxaemia stratum, 48-h mortality was 1.1% for HFNT vs. 2.5% LFO and 1.4% for permissive hypoxaemia. In the hypoxaemia stratum, adjusted odds ratio for 48-h mortality in liberal vs permissive comparison was 1.16 (0.49–2.74; p = 0.73); HFNT vs LFO comparison was 0.60 (0.33–1.06; p = 0.08). Strata-specific 28 day mortality rates were, respectively: 18.6, 23.4 and 3.3, 4.1, 3.9%. Neurocognitive sequelae were rare. Conclusions Respiratory support with HFNT showing potential benefit should prompt further trials. Supplementary Information The online version contains supplementary material available at 10.1007/s00134-021-06385-3.
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Affiliation(s)
- K Maitland
- Department of Infectious Disease and and Institute of Global Health and Innovation, Division of Medicine, Imperial College, London, UK. .,Kilifi County Hospital and Kenya Medical Research Institute (KEMRI) Wellcome Trust Research Programme, Kilifi, Kenya.
| | - S Kiguli
- School of Medicine, Makerere University and Mulago Hospital Kampala, Kampala, Uganda
| | - P Olupot-Olupot
- Faculty of Health Sciences, Mbale Campus and Mbale Regional Referral Hospital Mbale (POO, WO), Busitema University, Mbale, Uganda
| | - M Hamaluba
- Kilifi County Hospital and Kenya Medical Research Institute (KEMRI) Wellcome Trust Research Programme, Kilifi, Kenya
| | - K Thomas
- Intensive Care National Audit and Research Centre, London, UK
| | - F Alaroker
- Soroti Regional Referral Hospital, Soroti, Uganda
| | - R O Opoka
- School of Medicine, Makerere University and Mulago Hospital Kampala, Kampala, Uganda.,Jinja Regional Referral Hospital Jinja, Jinja, Uganda
| | - A Tagoola
- Jinja Regional Referral Hospital Jinja, Jinja, Uganda
| | - V Bandika
- Coast General District Hospital, Mombasa, Kenya
| | - A Mpoya
- Kilifi County Hospital and Kenya Medical Research Institute (KEMRI) Wellcome Trust Research Programme, Kilifi, Kenya
| | - H Mnjella
- Kilifi County Hospital and Kenya Medical Research Institute (KEMRI) Wellcome Trust Research Programme, Kilifi, Kenya
| | - E Nabawanuka
- School of Medicine, Makerere University and Mulago Hospital Kampala, Kampala, Uganda
| | - W Okiror
- Faculty of Health Sciences, Mbale Campus and Mbale Regional Referral Hospital Mbale (POO, WO), Busitema University, Mbale, Uganda
| | - M Nakuya
- Soroti Regional Referral Hospital, Soroti, Uganda
| | - D Aromut
- Soroti Regional Referral Hospital, Soroti, Uganda
| | - C Engoru
- Soroti Regional Referral Hospital, Soroti, Uganda
| | - E Oguda
- Kilifi County Hospital and Kenya Medical Research Institute (KEMRI) Wellcome Trust Research Programme, Kilifi, Kenya
| | - T N Williams
- Department of Infectious Disease and and Institute of Global Health and Innovation, Division of Medicine, Imperial College, London, UK.,Kilifi County Hospital and Kenya Medical Research Institute (KEMRI) Wellcome Trust Research Programme, Kilifi, Kenya
| | - J F Fraser
- Critical Care Research Group and Intensive Care Service, University of Queensland, The Prince Charles Hospital, Brisbane, Australia
| | - D A Harrison
- Intensive Care National Audit and Research Centre, London, UK
| | - K Rowan
- Intensive Care National Audit and Research Centre, London, UK
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Makela M, Gordon P, Tu D, Soliman C, Coté GL, Maitland K, Lin PT. Benzene Derivatives Analysis Using Aluminum Nitride Waveguide Raman Sensors. Anal Chem 2020; 92:8917-8922. [PMID: 32460484 DOI: 10.1021/acs.analchem.0c00809] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Raman spectroscopy using aluminum nitride (AlN) optical waveguides was demonstrated for organic compound analysis. The AlN waveguide device was prepared by reactive sputtering deposition and complementary-metal-oxide semiconductor (CMOS) processes. A fundamental waveguide mode was observed over a broad visible spectrum and the waveguide evanescent wave was used to excite the Raman signals of the test analytes. The performance of the waveguide sensor was characterized by measuring the Raman spectra of the benzene derivative mixtures consisting of benzene, anisole, and toluene. The compositions and concentrations were resolved by correlating the obtained Raman spectrum with the characteristic Raman peaks associated with C-C, C-H, and C-O functional groups. With the advantages of real-time detection and enhanced Raman signal intensity, the AlN waveguides provided a sensor platform for nondestructive and online chemical compound monitoring.
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Jo JA, Cheng S, Cuenca-Martinez R, Duran-Sierra E, Malik B, Ahmed B, Maitland K, Cheng YSL, Wright J, Reese T. Endogenous Fluorescence Lifetime Imaging (FLIM) Endoscopy For Early Detection Of Oral Cancer And Dysplasia. Annu Int Conf IEEE Eng Med Biol Soc 2019; 2018:3009-3012. [PMID: 30441030 DOI: 10.1109/embc.2018.8513027] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
We have performed a pilot clinical study, in which multispectral endogenous fluorescence (or autofluorescence) lifetime imaging (FLIM) was performed on clinically suspicious oral lesions of 73 patients undergoing tissue biopsy for oral dysplasia and cancer diagnosis. The results from this pilot study indicated that mild-dysplasia and early stage oral cancer could be detected from benign lesions using a computed aided diagnosis system developed based on biochemical and metabolic biomarkers derived from the endogenous FLIM images. The diagnostic performance of this novel FLIM clinical tool was estimated using a leave-onepatient-out cross-validation approach, which reported levels of sensitivity >90%, specificity >85%, and Area Under the Receiving Operating Curve (ROC-AUC) >0.9.
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Ominde M, Sande J, Ooko M, Bottomley C, Benamore R, Park K, Ignas J, Maitland K, Bwanaali T, Gleeson F, Scott A. Reliability and validity of the World Health Organization reading standards for paediatric chest radiographs used in the field in an impact study of Pneumococcal Conjugate Vaccine in Kilifi, Kenya. PLoS One 2018; 13:e0200715. [PMID: 30044834 PMCID: PMC6059459 DOI: 10.1371/journal.pone.0200715] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2017] [Accepted: 07/02/2018] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND Radiologically-confirmed pneumonia (RCP) is a specific end-point used in trials of Pneumococcal Conjugate Vaccine (PCV) to estimate vaccine efficacy. However, chest radiograph (CXR) interpretation varies within and between readers. We measured the repeatability and reliability of paediatric CXR interpretation using percent agreement and Cohen's Kappa and the validity of field readings against expert review in a study of the impact of PCV on pneumonia. METHODS CXRs were obtained from 2716 children admitted between 2006 and 2014 to Kilifi County Hospital, Kilifi, Kenya, with clinically-defined severe or very-severe pneumonia. Five clinicians and radiologists attended a three-day training course on CXR interpretation using a WHO standard. All CXRs were read once by two local primary readers. Discordant readings and 13% of concordant readings were arbitrated by a panel of three expert radiologists. To assess repeatability, a 5% median random sample was presented twice. Sensitivity and specificity of the primary readers' interpretations was estimated against the 'gold-standard' of the arbitrators' results. RESULTS Of 2716 CXRs, 2 were uninterpretable and 159 were evaluated twice. The percent agreement and Kappa for RCP were 89% and 0.68 and ranged between 84-97% and 0.19-0.68, respectively, for all pathological findings. Intra-observer repeatability was similar to inter-observer reliability. Sensitivities of the primary readers to detect RCP were 69% and 73%; specificities were 96% and 95%. CONCLUSION Intra- and inter-observer agreements on interpretations of radiologically-confirmed pneumonia are fair to good. Reasonable sensitivity and high specificity make radiologically-confirmed pneumonia, determined in the field, a suitable measure of relative vaccine effectiveness.
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Affiliation(s)
- M. Ominde
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
- Aga Khan University Hospital, Nairobi, Kenya
| | - J. Sande
- Aga Khan University Hospital, Nairobi, Kenya
| | - M. Ooko
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - C. Bottomley
- Department of Infectious Disease Epidemiology, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - R. Benamore
- Oxford University Hospitals Foundation NHS Trust, Oxford, United Kingdom
| | - K. Park
- Oxford University Hospitals Foundation NHS Trust, Oxford, United Kingdom
| | - J. Ignas
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - K. Maitland
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
- Imperial College, London, United Kingdom
| | - T. Bwanaali
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
- Department of Infectious Disease Epidemiology, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - F. Gleeson
- Oxford University Hospitals Foundation NHS Trust, Oxford, United Kingdom
- Oxford University, Oxford, United Kingdom
| | - A. Scott
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
- Department of Infectious Disease Epidemiology, London School of Hygiene & Tropical Medicine, London, United Kingdom
- Oxford University, Oxford, United Kingdom
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Iro MA, Sell T, Brown N, Maitland K. Rapid intravenous rehydration of children with acute gastroenteritis and dehydration: a systematic review and meta-analysis. BMC Pediatr 2018; 18:44. [PMID: 29426307 PMCID: PMC5807758 DOI: 10.1186/s12887-018-1006-1] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/05/2016] [Accepted: 01/23/2018] [Indexed: 12/01/2022] Open
Abstract
Background The World Health Organization (WHO) recommends rapid intravenous rehydration, using fluid volumes of 70-100mls/kg over 3–6 h, with some of the initial volume given rapidly as initial fluid boluses to treat hypovolaemic shock for children with acute gastroenteritis (AGE) and severe dehydration. The evidence supporting the safety and efficacy of rapid versus slower rehydration remains uncertain. Methods We conducted a systematic review of randomised controlled trials (RCTs) on 11th of May 2017 comparing different rates of intravenous fluid therapy in children with AGE and moderate or severe dehydration, using standard search terms. Two authors independently assessed trial quality and extracted data. Non-RCTs and non-English articles were excluded. The primary endpoint was mortality and secondary endpoints included adverse events (safety) and treatment efficacy. Main results Of the 1390 studies initially identified, 18 were assessed for eligibility. Of these, 3 studies (n = 464) fulfilled a priori criteria for inclusion; most studied children with moderate dehydration and none were conducted in resource-poor settings. Volumes and rates of fluid replacement varied from 20 to 60 ml/kg given over 1-2 h (fast) versus 2-4 h (slow). There was substantial heterogeneity in methodology between the studies with only one adjudicated to be of high quality. There were no deaths in any study. Safety endpoints only identified oedema (n = 6) and dysnatraemia (n = 2). Pooled analysis showed no significant difference between the rapid and slow intravenous rehydration groups for the proportion of treatment failures (N = 468): pooled RR 1.30 (95% CI: 0.87, 1.93) and the readmission rates (N = 439): pooled RR 1.39 (95% CI: 0.68, 2.85). Conclusions Despite wide implementation of WHO Plan C guideline for severe AGE, we found no clinical evaluation in resource-limited settings, and only limited evaluation of the rate and volume of rehydration in other parts of the world. Recent concerns over aggressive fluid expansion warrants further research to inform guidelines on rates of intravenous rehydration therapy for severe AGE. Electronic supplementary material The online version of this article (10.1186/s12887-018-1006-1) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- M A Iro
- Oxford Vaccine Group, Department of Paediatrics and the NIHR Biomedical Research Centre, University of Oxford, Headington, Oxford, OX3 7LE, UK
| | - T Sell
- Oxford Vaccine Group, Department of Paediatrics and the NIHR Biomedical Research Centre, University of Oxford, Headington, Oxford, OX3 7LE, UK
| | - N Brown
- Department of Paediatrics, Salisbury District Hospital, Salisbury, SP2 8BJ, UK.,Department of Child Health, Aga Khan University, Karachi, Pakistan
| | - K Maitland
- Department of Paediatrics, Faculty of Medicine, Wellcome Trust Centre for Clinical Tropical Medicine, Imperial College, W2 1PG, London, UK. .,Clinical Trials Facility, KEMRI Wellcome Trust Research Programme, PO Box 230, Kilifi, Kenya.
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See Hoe L, Obonyo N, Byrne L, Shiino K, Diab S, Dunster K, Passmore M, Boon C, Engkilde-Pedersen S, Esguerra A, Fauzi M, Pretti Pimenta L, Simonova G, Van Haren F, Shekar K, Anstey C, Tung J, Cullen L, Platts D, Chan J, Maitland K, Fraser J. Fluid Resuscitation with 0.9% Saline Impairs Myocardial Contractility in an Ovine Model of Endotoxaemic Shock. Heart Lung Circ 2018. [DOI: 10.1016/j.hlc.2018.06.129] [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: 10/28/2022]
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Robinson M, Marks H, Hinsdale T, Maitland K, Coté G. Rapid isolation of blood plasma using a cascaded inertial microfluidic device. Biomicrofluidics 2017; 11:024109. [PMID: 28405258 PMCID: PMC5367146 DOI: 10.1063/1.4979198] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2017] [Accepted: 03/14/2017] [Indexed: 05/21/2023]
Abstract
Blood, saliva, mucus, sweat, sputum, and other biological fluids are often hindered in their ability to be used in point-of-care (POC) diagnostics because their assays require some form of off-site sample pre-preparation to effectively separate biomarkers from larger components such as cells. The rapid isolation, identification, and quantification of proteins and other small molecules circulating in the blood plasma from larger interfering molecules are therefore particularly important factors for optical blood diagnostic tests, in particular, when using optical approaches that incur spectroscopic interference from hemoglobin-rich red blood cells (RBCs). In this work, a sequential spiral polydimethylsiloxane (PDMS) microfluidic device for rapid (∼1 min) on-chip blood cell separation is presented. The chip utilizes Dean-force induced migration via two 5-loop Archimedean spirals in series. The chip was characterized in its ability to filter solutions containing fluorescent beads and silver nanoparticles and further using blood solutions doped with a fluorescent protein. Through these experiments, both cellular and small molecule behaviors in the chip were assessed. The results exhibit an average RBC separation efficiency of ∼99% at a rate of 5.2 × 106 cells per second while retaining 95% of plasma components. This chip is uniquely suited for integration within a larger point-of-care diagnostic system for the testing of blood plasma, and the use of multiple filtering spirals allows for the tuning of filtering steps, making this device and the underlying technique applicable for a wide range of separation applications.
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Affiliation(s)
- M Robinson
- Department of Biomedical Engineering, Texas A&M University , College Station, Texas 77843, USA
| | - H Marks
- Department of Biomedical Engineering, Texas A&M University , College Station, Texas 77843, USA
| | - T Hinsdale
- Department of Biomedical Engineering, Texas A&M University , College Station, Texas 77843, USA
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Hoste EA, Maitland K, Brudney CS, Mehta R, Vincent JL, Yates D, Kellum JA, Mythen MG, Shaw AD. Four phases of intravenous fluid therapy: a conceptual model. Br J Anaesth 2014; 113:740-7. [PMID: 25204700 DOI: 10.1093/bja/aeu300] [Citation(s) in RCA: 181] [Impact Index Per Article: 18.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
I.V. fluid therapy plays a fundamental role in the management of hospitalized patients. While the correct use of i.v. fluids can be lifesaving, recent literature demonstrates that fluid therapy is not without risks. Indeed, the use of certain types and volumes of fluid can increase the risk of harm, and even death, in some patient groups. Data from a recent audit show us that the inappropriate use of fluids may occur in up to 20% of patients receiving fluid therapy. The delegates of the 12th Acute Dialysis Quality Initiative (ADQI) Conference sought to obtain consensus on the use of i.v. fluids with the aim of producing guidance for their use. In this article, we review a recently proposed model for fluid therapy in severe sepsis and propose a framework by which it could be adopted for use in most situations where fluid management is required. Considering the dose-effect relationship and side-effects of fluids, fluid therapy should be regarded similar to other drug therapy with specific indications and tailored recommendations for the type and dose of fluid. By emphasizing the necessity to individualize fluid therapy, we hope to reduce the risk to our patients and improve their outcome.
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Affiliation(s)
- E A Hoste
- Department of Intensive Care Medicine, 2K12-C, Ghent University Hospital, Ghent University, De Pintelaan 185, 9000 Ghent, Belgium Research Foundation Flanders (FWO), Brussels, Belgium
| | - K Maitland
- KEMRI-Wellcome Trust Research Programme, PO Box 230, Kilifi, Kenya Wellcome Trust Centre for Clinical Tropical Medicine, Department of Paediatrics, Faculty of Medicine, Imperial College, London, UK
| | - C S Brudney
- Department of Anesthesiology, Duke University Medical Center/Durham VAMC, Durham, NC, USA
| | - R Mehta
- Division of Nephrology and Hypertension, Department of Medicine, University of California, San Diego, San Diego, CA, USA
| | - J-L Vincent
- Department of Intensive Care, Erasme University Hospital, Université Libre de Bruxelles, Brussels, Belgium
| | - D Yates
- Department of Anaesthesia, York Teaching Hospital NHS Foundation Trust, York, UK
| | - J A Kellum
- Center for Critical Care Nephrology, CRISMA Center, Department of Critical Care Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - M G Mythen
- Department of Anaesthesia, University College London, London, UK
| | - A D Shaw
- Department of Anesthesiology, Vanderbilt University Medical Center, Nashville, TN, USA
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Malik B, Jabbour J, Cheng S, Cuenca R, Jo J, Wright J, Cheng Y, Maitland K. Macro- and Microscopic Optical Imaging Toward Diagnosis Of Oral Epithelial Dysplasia. Oral Surg Oral Med Oral Pathol Oral Radiol 2013. [DOI: 10.1016/j.oooo.2013.09.030] [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: 10/26/2022]
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Abubakar A, Holding P, Mwangome M, Maitland K. Maternal perceptions of factors contributing to severe under-nutrition among children in a rural African setting. Rural Remote Health 2011; 11:1423. [PMID: 21323398 PMCID: PMC3651965] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/30/2023] Open
Abstract
INTRODUCTION In developing countries, severe undernutrition in early childhood is associated with increased mortality and morbidity, and 10-40% of hospital admissions. The current study aimed to elicit maternal perceptions of factors that contribute to severe undernutrition among children in a rural Kenyan community in order to identify appropriate and acceptable targeted interventions. METHODS The study consisted of 10 focus group discussions (FGDs) of between eight and ten mothers each, in a rural coastal community in Kenya. A grounded theory approach was used to analyse the FGD data. RESULTS In all FGDs 'financial constraints' was the main reason given for severe undernutrition of children. The mothers reported the additional factors of inadequate food intake, ill health, inadequate care of children, heavy workload for mothers, inadequate control of family resources by women and a lack of resources for generating income for the family. The mothers also reported their local cultural belief that severe malnutrition was due to witchcraft and the violation of sexual taboos. CONCLUSIONS The mothers in the study community recognised multiple aetiologies for severe undernutrition. A multidisciplinary approach is needed address the range of issues raised and so combat severe undernutrition. Suggested interventions include poverty alleviation, medical education and psychosocial strategies. The content and approach of any program must address the need for variability, determined by individual and local needs, concerns, attitudes and beliefs.
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Affiliation(s)
- A Abubakar
- KEMRI-Wellcome Trust Research Programme, Centre for Geographic Medicine Research-Coast, Kilifi, Kenya
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14
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Yacoub S, Lang HJ, shebbe M, Twimba M, Ohuma E, Tulloh R, Maitland K. Cardiac function and haemodynamics in African children with severe malaria. Int J Infect Dis 2010. [DOI: 10.1016/j.ijid.2010.02.1736] [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: 10/19/2022] Open
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Olotu A, Ndiritu M, Ismael M, Mohammed S, Mithwani S, Maitland K, Newton CRJC. Characteristics and outcome of cardiopulmonary resuscitation in hospitalised African children. Resuscitation 2008; 80:69-72. [PMID: 19013705 PMCID: PMC2706393 DOI: 10.1016/j.resuscitation.2008.09.019] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2008] [Revised: 09/15/2008] [Accepted: 09/30/2008] [Indexed: 11/21/2022]
Abstract
Objective To review the characteristics and outcome of cardiopulmonary resuscitation in children at a rural hospital in Kenya. Patients and method All children aged 0–14 years who experienced ≥1 episode of respiratory or cardiopulmonary arrest during April 2002–2004 were prospectively identified. Demographic variables, cause of hospitalisation, type and duration of arrest, resuscitation measures taken and outcomes were determined. Results 114 children experienced at least one episode of respiratory arrest (RA) or cardiopulmonary arrest (CPA). Cardiopulmonary resuscitation (CPR) was performed on all children. “Do not resuscitate order” (DNR) was given in 15 patients after initial resuscitation. Eighty two patients (72%) had RA and 32 (28%) had CPA. 25/82 (30%) patients with RA survived initial CPR compared to 5/32 (16%) with CPA. Survival at discharge was 22% (18/82) in children who had RA while no one with CPA survived at discharge. The leading underlying diseases were severe malaria, septicaemia and severe malnutrition. Prolonged resuscitation beyond 15 min and receiving adrenaline [epinephrine] (at least one dose of 10 μg/kg IV) were predictive of poor final outcome. Conclusion Cardiopulmonary arrest after admission has a very poor prognosis in our hospital. Infectious diseases are the main underlying causes of arrest. If a child fails to respond to the basic tenements of PALS within 15 min then it is unlikely that further efforts to sustain life will be fruitful in hospitals where ventilation facilities are not present.
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Affiliation(s)
- A Olotu
- KEMRI/Welcome Trust Collaborative Research, Centre for Geographic Medicine Research, Coast, Kilifi, Kenya.
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16
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Hassall O, Ngina L, Kongo W, Othigo J, Mandaliya K, Maitland K, Bates I. The acceptability to women in Mombasa, Kenya, of the donation and transfusion of umbilical cord blood for severe anaemia in young children. Vox Sang 2007; 94:125-31. [PMID: 18067489 PMCID: PMC2607521 DOI: 10.1111/j.1423-0410.2007.01012.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Background and Objectives Severe anaemia, for which a blood transfusion can be life saving, is common in hospitalized children in sub-Saharan Africa but blood for transfusion is often in short supply. Umbilical cord blood is usually thrown away but could be a useful source of red cells for small volume transfusions in young children in this setting. The objective of this study was to evaluate the attitudes of women using the maternity services of the provincial hospital in Mombasa, Kenya, towards cord blood donation and transfusion, and essential aspects of this process including informed consent and the acceptability of screening for human immunodeficiency virus (HIV) infection. Materials and Methods A structured questionnaire was developed based on data provided by focus group discussions with women attending the hospital's maternity unit and administered to women who had recently delivered at the hospital. Results Of the 180 women who completed a questionnaire, the donation and transfusion of cord blood were acceptable to 81% and 78%, respectively. Ninety per cent of women who supported cord blood donation were willing to undergo further HIV testing at the time of delivery. Seventy-seven per cent of women wanted informed consent to be sought for cord blood donation and 66% of these felt they could make this decision alone. Conclusion The donation of umbilical cord blood and its transfusion are acceptable to the majority of women delivering at Coast Provincial General Hospital, Mombasa. Findings from the study will benefit the planned cord blood donation programme at this facility.
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Affiliation(s)
- O Hassall
- Centre for Geographic Medicine Research (Coast), Kenya Medical Research Institute/Wellcome Trust Research Programme, Kilifi, Kenya.
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Khor CC, Vannberg FO, Chapman SJ, Walley A, Aucan C, Loke H, White NJ, Peto T, Khor LK, Kwiatkowski D, Day N, Scott A, Berkley JA, Marsh K, Peshu N, Maitland K, Williams TN, Hill AVS. Positive replication and linkage disequilibrium mapping of the chromosome 21q22.1 malaria susceptibility locus. Genes Immun 2007; 8:570-6. [PMID: 17703179 PMCID: PMC2850168 DOI: 10.1038/sj.gene.6364417] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2007] [Revised: 07/05/2007] [Accepted: 07/05/2007] [Indexed: 11/09/2022]
Abstract
Four cytokine receptor genes are located on Chr21q22.11, encoding the alpha and beta subunits of the interferon-alpha receptor (IFNAR1 and IFNAR2), the beta subunit of the interleukin 10 receptor (IL10RB) and the second subunit of the interferon-gamma receptor (IFNGR2). We previously reported that two variants in IFNAR1 were associated with susceptibility to malaria in Gambians. We now present an extensive fine-scale mapping of the associated region utilizing 45 additional genetic markers obtained from public databases and by sequencing a 44 kb region in and around the IFNAR1 gene in 24 Gambian children (12 cases/12 controls). Within the IFNAR1 gene, a newly studied C --> G single-nucleotide polymorphism (IFNAR1 272354c-g) at position -576 relative to the transcription start was found to be more strongly associated with susceptibility to severe malaria. Association was observed in three populations: in Gambian (P=0.002), Kenyan (P=0.022) and Vietnamese (P=0.005) case-control studies. When all three studies were combined, using the Mantel-Haenszel test, the presence of IFNAR1 -576G was associated with a substantially elevated risk of severe malaria (N=2444, OR=1.38, 95% CI: 1.17-1.64; P=1.7 x 10(-4)). This study builds on previous work to further highlight the importance of the type-I interferon pathway in malaria susceptibility and illustrates the utility of typing SNPs within regions of high linkage disequilibrium in multiple populations to confirm initial positive associations.
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Affiliation(s)
- C C Khor
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, UK.
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Eziefula A, Mwakisha N, Macharia A, Williams T, Maitland K, Lowe B, Dondorp A, Newton C. Correlates of Red Blood Cell Deformability (RCD) in Severe Falciparum Malaria. The Effect of Thalassaemia Status and Parasite Biomass. J Infect 2007. [DOI: 10.1016/j.jinf.2006.10.010] [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: 11/16/2022]
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Idro R, Aketch S, Gwer S, Newton CRJC, Maitland K. Research priorities in the management of severe Plasmodium falciparum malaria in children. Ann Trop Med Parasitol 2006; 100:95-108. [PMID: 16492357 DOI: 10.1179/136485906x91459] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Severe malaria is a common reason for admission to paediatric wards in hospitals across sub-Saharan Africa. Despite over 100 years of research, mortality remains high. Deaths are associated with severe metabolic acidosis, shock, severe anaemia, hypoglycaemia, impaired consciousness, raised intracranial pressure, and status epilepticus. Most inpatient deaths occur within 24 h of admission to hospital, before the beneficial effects of treatment with antimalarial drugs are achieved. This review covers the priority areas for research in the care of children with severe malaria, addressing each of the main risk factors associated with death, in a bid to reduce the inpatient mortality.
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Affiliation(s)
- R Idro
- Centre for Geographic Medicine Research - Coast, Kenya Medical Research Institute/Wellcome Trust Research Laboratories, P.O. Box 230, Kilifi, Kenya.
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Maitland K, Bunce M, Harding RM, Barnardo MCNM, Clegg JB, Welsh K, Bowden DK, Williams TN. HLA class-I and class-II allele frequencies and two-locus haplotypes in Melanesians of Vanuatu and New Caledonia. ACTA ACUST UNITED AC 2005; 64:678-86. [PMID: 15546341 DOI: 10.1111/j.1399-0039.2004.00328.x] [Citation(s) in RCA: 5] [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: 11/29/2022]
Abstract
HLA class-I and class-II allele frequencies and two-locus haplotypes were examined in 367 unrelated Melanesians living on the islands of Vanuatu and New Caledonia. Diversity at all HLA class-I and class-II loci was relatively limited. In class-I loci, three HLA-A allelic groups (HLA-A*24, HLA-A*34 and HLA-A*11), seven HLA-B alleles or allelic groups (HLA-B*1506, HLA-B*5602, HLA-B*13, HLA-B*5601, HLA-B*4001, HLA-B*4002 and HLA-B*2704) and four HLA-C alleles or allelic groups (HLA-Cw*04, HLA-Cw*01, HLA-Cw*0702 and HLA-Cw*15) constituted more than 90% of the alleles observed. In the class-II loci, four HLA-DRB1 alleles (HLA-DRB1*15, HLA-DRB1*11, HLA-DRB1*04 and HLA-DRB1*16), three HLA-DRB3-5 alleles (HLA-DRB3*02, HLA-DRB4*01 and HLA-DRB5*01/02) and five HLA-DQB1 alleles (HLA-DQB1*0301, HLA-DQB1*04, HLA-DQB1*05, HLA-DQB1*0601 and HLA-DQB1*0602) constituted over 93, 97 and 98% of the alleles observed, respectively. Homozygosity showed significant departures from expected levels for neutrality based on allele frequency (i.e. excess diversity) at the HLA-B, HLA-Cw, HLA-DQB1 and HLA-DRB3/5 loci on some islands. The locus with the strongest departure from neutrality was HLA-DQB1, homozygosity being significantly lower than expected on all islands except New Caledonia. No consistent pattern was demonstrated for any HLA locus in relation to malaria endemicity.
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Affiliation(s)
- K Maitland
- MRC Molecular Haematology Unit, Weatherall Institute of Molecular Medicine, Oxford, UK.
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Abstract
AIMS To determine whether delayed capillary refill time (>3 seconds) is a useful prognostic indicator in Kenyan children admitted to hospital. METHODS A total of 4160 children admitted to Kilifi District Hospital with malaria, malarial anaemia, acute respiratory tract infection (ARI), severe anaemia (haemoglobin <50 g/l), gastroenteritis, malnutrition, meningitis, or septicaemia were studied. RESULTS Overall, delayed capillary refill time (dCRT), present in 346/4160 (8%) of the children, was significantly more common in fatal cases (44/189, 23%) than survivors (7.5%), and had useful prognostic value. In children admitted with malaria, gastroenteritis, or malnutrition, likelihood ratio tests suggested that dCRT was useful in identifying high risk groups for mortality, but its prognostic value in anaemia, ARI, and sepsis was unclear due to low case fatality or limited numbers. The severity features of impaired consciousness and deep breathing were significantly associated both with the presence of dCRT and fatal outcome. In children, with either of these severity features, a less stringent value of dCRT(>2 s) identified 50% of children with hypotension (systolic BP <2SD) and 40% of those requiring volume resuscitation (for metabolic acidosis). CONCLUSIONS Although CRT is a simple bedside test, which may be used in resource poor settings as a guide to the circulatory status, dCRT should not be relied on in the absence of other features of severity. In non-severe disease, the additional presence of hypoxia, a moderately raised creatinine (>80 micromol/l), or a raised white cell count should prompt the need for fluid expansion.
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Affiliation(s)
- A Pamba
- Centre for Geographic Medicine Research, Coast, KEMRI/Wellcome Trust Unit, PO Box 230, Kilifi, Kenya
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Abstract
Shock is often under-reported in children attending hospitals in developing countries. Readily obtainable features of shock (capillary refill time, temperature gradient, pulse volume, and signs of dehydration) are widely used to help prioritise management in the emergency assessment of critically ill or injured children. However, data are lacking on their validity, including, importantly, reproducibility between observers. Agreement of these signs was examined in 100 consecutive children admitted to a paediatric ward on the coast of Kenya. After an initial training of clinical sign recognition, there was moderate agreement for most features of cardiovascular compromise (delayed capillary refill > or =4 s, kappa = 0.49; and weak pulse volume, kappa = 0.4) and only substantial agreement for temperature gradient (kappa = 0.62). For hydration status, only in the assessment of skin turgor was there a moderate level of agreement (kappa = 0.55). Capillary refill times and assessment of pulse volume recommended by the recent American consensus guidelines achieved only a "low" moderate to poor interrater agreement, questioning the reliability of such parameters.
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Affiliation(s)
- H Otieno
- The Centre for Geographic Medicine Research, Coast, KEMRI, Kenya, PO Box 230, Kilifi, Kenya
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Abstract
To raise clinicians' awareness of chronic (therapeutic) salicylate poisoning as a common cause of admission in paediatric patients presenting to hospital with respiratory distress (a clinical manifestation of metabolic acidosis) and a history of 'over the counter' treatment with salicylate (Aspirin). We present two complex cases and provide a review of the literature on pathogenesis, clinical presentation and management of salicylate poisoning. A complete history of the illness, including questions on drug use, is vital in assessing the cause of metabolic acidosis in children. Due to the limited options available in managing such patients in many developing countries, emphasis should be placed on prevention of poisoning by educating the community and health care providers.
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Affiliation(s)
- C O Musumba
- Kenya Medical Research Institute, Centre for Geographic Medicine Research, Coast, P.O. Box 230, Kilifi, Kenya
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Abstract
BACKGROUND The role of volume resuscitation in severe Plasmodium falciparum malaria is controversial. AIM To examine the role of hypovolaemia in severe childhood malaria. STUDY DESIGN Retrospective review. METHODS We studied 515 children admitted with severe malaria to a high-dependency unit (HDU) in Kilifi, Kenya. On admission to the HDU, children underwent a further assessment of vital signs and a standard clinical examination. RESULTS Factors associated with a fatal outcome included deep breathing or acidosis (base excess below -8), hypotension (systolic blood pressure <80 mmHg), raised plasma creatinine (>80 micro mol/l), low oxygen saturation (<90%), dehydration and hypoglycaemia (<2.5 mmol/l). Shock was present in 212/372 (57%) children, of whom 37 (17.5%) died, and was absent in 160, of who only 7 (4.4%) died (chi(2) = 14.9; p = 0.001). DISCUSSION Impaired tissue perfusion may play a role in the mortality of severe malaria. Moreover, volume resuscitation, an important life-saving intervention in children with hypovolaemia, should be considered in severe malaria with evidence of impaired tissue perfusion.
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Affiliation(s)
- K Maitland
- Centre for Geographic Medicine Research, Coast, KEMRI/Wellcome Trust Unit, P.O. Box 230, Kilifi, Kenya.
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Craig NJ, Durán Alonso MB, Hawker KL, Shiels P, Glencorse TA, Campbell JM, Bennett NK, Canham M, Donald D, Gardiner M, Gilmore DP, MacDonald RJ, Maitland K, McCallion AS, Russell D, Payne AP, Sutcliffe RG, Davies RW. A candidate gene for human neurodegenerative disorders: a rat PKC gamma mutation causes a Parkinsonian syndrome. Nat Neurosci 2001; 4:1061-2. [PMID: 11600890 DOI: 10.1038/nn740] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- N J Craig
- University of Glasgow, Institute of Biomedical and Life Sciences, Glasgow G12 8QQ, Scotland, UK
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Cayatte AJ, Rupin A, Oliver-Krasinski J, Maitland K, Sansilvestri-Morel P, Boussard MF, Wierzbicki M, Verbeuren TJ, Cohen RA. S17834, a new inhibitor of cell adhesion and atherosclerosis that targets nadph oxidase. Arterioscler Thromb Vasc Biol 2001; 21:1577-84. [PMID: 11597929 DOI: 10.1161/hq1001.096723] [Citation(s) in RCA: 88] [Impact Index Per Article: 3.8] [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] [Indexed: 11/16/2022]
Abstract
microdant stress is involved in the events that accompany endothelial cell expression of adhesion molecules and leukocyte adherence in many disease states, including atherosclerosis. A recently discovered benzo(b)pyran-4-one derivative, S17834 (10 to 50 micromol/L), reduced tumor necrosis factor-stimulated vascular cell adhesion molecule-1 (VCAM) mRNA accumulation and protein expression in human umbilical vein endothelial cells. Intercellular cell adhesion molecule-1 and E-selectin were also inhibited by S17834, but platelet endothelial cell adhesion molecule-1 was not. Adherence of U937 monocytic cells to the endothelial cells as well as to plastic plates coated with soluble VCAM, intercellular cell adhesion molecule-1, P-selectin, and E-selectin was also decreased. Consistent with an antioxidant mechanism of action, S17834 (10 to 50 micromol/L) inhibited tumor necrosis factor-stimulated release of superoxide from endothelial cells measured by cytochrome c reduction. S17834 had no effect on superoxide produced by xanthine oxidase, indicating that rather than by acting as a scavenger of superoxide anion, the drug acts by inhibiting the production of free radicals. Indeed, S17834 inhibited NADPH oxidase activity of endothelial cell membranes. The ability to inhibit superoxide anion production appears to be key in the effect of S17834 on superoxide anion production and VCAM expression, because these actions were mimicked by adenovirus-mediated overexpression of superoxide dismutase. Furthermore, these actions may be relevant in vivo, because S17834 reduced aortic superoxide anion levels by 40% and aortic atherosclerotic lesions by 60% in apolipoprotein E-deficient mice. These results indicate that S17834 inhibits adhesion molecule expression and adherence of leukocytes to endothelial cells as well as aortic atherogenesis and that perhaps these effects can be explained by its ability to inhibit endogenous superoxide anion production.
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Affiliation(s)
- A J Cayatte
- Vascular Biology Unit, Boston University Medical Center, Boston, Massachusetts, USA
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Maitland K, Kyes S, Williams TN, Newbold CI. Genetic restriction of Plasmodium falciparum in an area of stable transmission: an example of island evolution? Parasitology 2000; 120 ( Pt 4):335-43. [PMID: 10811274 DOI: 10.1017/s0031182099005612] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
To date, a high degree of polymorphism has been demonstrated at both the MSP1 and MSP2 loci in parasites from areas of stable malaria transmission. As a consequence, in such areas it is rare to find parasites of the same 2-locus genotype in more than 1 subject. We have studied MSP1 and MSP2 diversity in parasites collected from subjects with both symptomatic (n = 86) and asymptomatic (34) malaria living on the island of Santo, Vanuatu, an area of stable malaria transmission. Polymorphism at the MSP1 and MSP2 loci was considerably less than previously reported: only 5 MSP1 and 5 MSP2 alleles were detected and these showed no size variation within alleles. Santo is unique amongst the areas studied so far in that it is a small island at the limit of the malaria belt in the South Pacific. Thus, the evolution of the parasite population may have been affected by the small size and isolation of this island population. Moreover, limited parasite diversity may explain the unusually mild nature of Plasmodium falciparum disease on Santo. Islands have fascinated biologists for centuries and fuelled the advancement of evolutionary theory, since they are natural laboratories for the study of evolution. The simplicity of the Vanuatu P. falciparum population may facilitate the use and interpretation of sequence level analyses to address the mechanisms by which genetic diversity is generated and maintained in natural populations.
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Affiliation(s)
- K Maitland
- Institute of Molecular Medicine, John Radcliffe Hospital, Headington, Oxford, UK.
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Williams TN, Maitland K, Rees DC, Peto TE, Bowden DK, Weatherall DJ, Clegg JB. Reduced soluble transferrin receptor concentrations in acute malaria in Vanuatu. Am J Trop Med Hyg 1999; 60:875-8. [PMID: 10344669 DOI: 10.4269/ajtmh.1999.60.875] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [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] [Indexed: 11/07/2022] Open
Abstract
Soluble transferrin receptor (sTfR) concentration is a sensitive index of iron deficiency when used in conjunction with ferritin measurements in adults. One advantage of this assay is that unlike ferritin it does not appear to be affected by a range of infectious and inflammatory conditions or by pregnancy, rendering it a promising adjunct to the diagnosis of iron deficiency in tropical populations. We have measured plasma sTfR concentrations in a group of malaria patients (n = 21) and asymptomatic (18) and aparasitemic (76) controls in Vanuatu. Plasma sTfR concentration was significantly reduced in individuals with acute malaria (P = 0.003). While this observation provides evidence that erythropoeitic suppression may be an important etiologic component in malarial anemia, it also suggests that malaria may be a confounding factor when interpreting sTfR concentrations in such populations. The role of sTfR in the diagnosis of iron deficiency in tropical populations remains to be established.
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Affiliation(s)
- T N Williams
- Institute of Molecular Medicine, John Radcliffe Hospital, Headington, Oxford, United Kingdom
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Williams TN, Maitland K. Reply from williams and maitland. Parasitol Today 1999; 15:167-8. [PMID: 10323752 DOI: 10.1016/s0169-4758(99)01424-6] [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] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Affiliation(s)
- TN Williams
- Molecular Parasitology Group Institute of Molecular Medicine John Radcliffe Hospital, Oxford, UK OX3 9DS
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Abstract
Although alpha+ thalassaemia is the commonest haemoglobinopathy in the world, it is not known if it is associated with significant ineffective erythropoiesis, a fact of importance in interpreting its complex interaction with malaria. To study this problem, we have measured the concentrations of soluble transferrin receptor (sTIR) and ferritin in 181 children from Vanuatu with heterozygous (68) and homozygous (46) alpha+ thalassaemia, and normal controls (67). sTfR concentrations were significantly higher in both homozygotes (mean 3.1 mg/l, range 2.8-3.4) and heterozygotes (2.86 mg/l, 2.6-3.2) compared to the normal controls (2.48 mg/l, 2.3-2.7), suggesting that although globin chain imbalance is minimal, there is ineffective erythropoiesis in both these conditions. Age was also shown to significantly affect sTfR, with peak levels occurring in the 5-9 years age group. Ferritin concentrations showed a similar trend, being higher in the thalassaemic groups, although this did not reach statistical significance. No individuals had low ferritin concentrations, although two had significantly elevated sTfR levels. These observations suggest that the alpha+ thalassaemia phenotype includes an expansion of the erythron, and may suggest possible mechanisms for the increased susceptibility in babies with alpha thalassaemia to both P. falciparum and P. vivax malaria.
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Affiliation(s)
- D C Rees
- MRC Molecular Haematology Unit, Institute of Molecular Medicine, University of Oxford, The John Radcliffe Hospital
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33
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Affiliation(s)
- K Maitland
- Molecular Parasitology Group, Institute of Molecular Medicine, John Radcliffe Hospital, Oxford, UK OX3 9DS
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34
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Maitland K, Williams T. Reply. Parasitol Today 1998; 14:293. [PMID: 17040788 DOI: 10.1016/s0169-4758(98)01258-7] [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] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Affiliation(s)
- K Maitland
- Institute of Molecular Medicine, John Radcliffe Hospital, Oxford UK OX1 3PS
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35
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36
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Barnardo MC, Welsh KI, Vilches C, Maitland K, Bunce M. Allele-specific HLA-B*15 typing by PCR-SSP and its application to four distinct ethnic populations. Tissue Antigens 1998; 51:293-300. [PMID: 9550331 DOI: 10.1111/j.1399-0039.1998.tb03105.x] [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] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We present a set of primer mixes for the allele-specific typing of the HLA-B*15 group by PCR-SSP. The set comprises 46 primer mixes which are designed to unequivocally resolve all but two of the 666 possible combinations of the B*15 alleles, B*1501-37 (B*1536 sequence unavailable). A core subset of 34 of the 46 mixes can be used alone to give a high resolution B*15 typing set. This allows for the identification of each B*15 allele when present as the only B*15 allele and the majority of the possible B*15 homozygotic combinations. The method was validated using reference DNA samples and the B*15 allele frequency in 4 distinct ethnic populations was investigated. The results show that these populations contain predominantly mutually exclusive sets of B*15 alleles.
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Affiliation(s)
- M C Barnardo
- Transplantation Immunology, Oxford Transplant Centre, Churchill Hospital, United Kingdom.
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37
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Abstract
We studied the aetiology of malnutrition in a cohort of 1511 children < 10 years old in Espiritu Santo, Vanuatu. Malnutrition was categorized using standard anthropometric criteria as: underweight [weight-for-age (WA) Z score < -2], wasting [weight-for-height (WH) Z < -2], or stunting [height-for-age (HA) Z < -2]. On multiple logistic regression analysis, the only factors significantly associated with wasting were age < 5 years [OR (95% CI) 1.8 (1.2-2.9), p = 0.01] and having suffered one or more episodes of clinical P. vivax malaria in the 6 months preceding nutritional assessment [OR 2.4 (1.3-4.4), p = 0.006]. The incidence of P. vivax infection was significantly higher during the 6 months preceding assessment in underweight vs. non-underweight children [incidence rate ratio (IRR) 2.6 (1.5-4.4), p < or = 0.0001). These groups had similar incidences of clinical P. falciparum infection during the same period [IRR 1.1 (0.57-2.1) p = 0.8] and of either species during the 6 months following assessment [IRR P. vivax 1.3 (0.9-2.0) p = 0.2; IRR P. falciparum 1.3 (0.9-1.9) p = 0.2]. In these children, P. vivax malaria was a major predictor of acute malnutrition; P. falciparum was not. Wasting neither predisposed to nor protected against malaria of either species. Although P. vivax malaria is generally regarded as benign, it may produce considerable global mortality through malnutrition.
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Affiliation(s)
- T N Williams
- Institute of Molecular Medicine, John Radcliffe Hospital, Oxford, UK.
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38
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Maitland K, Williams TN, Kotecka BM, Edstein MD, Rieckmann KH. Plasma chloroquine concentrations in young and older malaria patients treated with chloroquine. Acta Trop 1997; 66:155-61. [PMID: 9210966 DOI: 10.1016/s0001-706x(97)00046-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [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] [Indexed: 02/04/2023]
Abstract
Plasma chloroquine (CQ) concentrations were measured by bioassay in young (0-4 years, n = 9) and older (5-60 years, n = 21) patients from Vanuatu infected with malaria following treatment with 25 mg/kg CQ over 3 days. CQ concentrations in young children tended to be lower than in older patients at days 2, 3, 4 and 7 after onset of treatment, with no drug present in two young children on day 3 and in one child on day 7. The greater difficulty experienced by young children to ingest all of their prescribed medication could have contributed to the lower CQ concentrations observed in the younger age group. The possibility that sub-therapeutic CQ concentrations are responsible for treatment failures in young children should be considered in areas where a high degree of CQ resistance has not yet been established. In such areas, the presence or prevalence of CQ-resistant infections should not be based on treatment failures observed in young children unless it can be confirmed that adequate blood CQ concentrations were achieved after treatment.
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Affiliation(s)
- K Maitland
- Institute of Molecular Medicine, John Radcliffe Hospital, Oxford, UK
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39
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Maitland K, Williams TN, Peto TE, Day KP, Clegg JB, Weatherall DJ, Bowden DK. Absence of malaria-specific mortality in children in an area of hyperendemic malaria. Trans R Soc Trop Med Hyg 1997; 91:562-6. [PMID: 9463668 DOI: 10.1016/s0035-9203(97)90026-2] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.2] [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] [Indexed: 02/06/2023] Open
Abstract
We conducted a prospective community-based malaria surveillance study on a cohort of children < 10 years old living in an area of hyperendemic malaria (spleen rates > 50% in children aged 2-9 years) in Vanuatu, Melanesia, supported by a concurrent prospective descriptive study of malaria admissions to the local hospital. The incidence of clinical malaria in children < 10 years old was 1.9 episodes/year. The annual incidence of severe malaria (severe malarial anaemia and cerebral malaria) was only 2/1000 in children aged < 5 years. The only manifestation of severe malaria seen in indigenous children was anaemia. No death could be attributed to malaria. While the incidence of uncomplicated clinical malaria in this population was comparable to that in many parts of Africa, the incidence of severe forms of the disease was significantly lower. This could not be attributed to differing rates of malaria transmission, chloroquine resistance, or to host protective or behavioural factors. These findings suggest that studies which compare disease patterns in geographically disparate populations may be instrumental in developing a better understanding of the determinants of clinical outcome in Plasmodium falciparum malaria and that such regional differences must be considered when planning or interpreting the effects of malaria interventions.
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Affiliation(s)
- K Maitland
- Institute of Molecular Medicine, John Radcliffe Hospital, Oxford, UK
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40
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Maitland K, Williams TN, Newbold CI. Plasmodium vevax and P. falciparum: Biological interactions and the possibility of cross-species immunity. ACTA ACUST UNITED AC 1997; 13:227-31. [PMID: 15275075 DOI: 10.1016/s0169-4758(97)01061-2] [Citation(s) in RCA: 94] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The question of whether infection of humans with one species of malaria parasite alters the course of infection with another has been largely ignored because no such interaction was found during studies of induced malaria in patients with neurosyphilis. However, in animal model systems some degree of cross-species interaction is the rule rather than the exception. Furthermore, recent epidemiological observations in Vanuatu in the South Pacific have suggested a biological interaction between the dominant species, Plasmodium vivax, and P. falciparum. Kathryn Maitland, Tom Williams and Chris Newbold here speculate on the basis of these observations and other published findings that infection with P. vivax may result in the development of immunity sufficient to ameliorate the clinical course of subsequent infections with the potentially lethal parasite P. falciparum.
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Affiliation(s)
- K Maitland
- Institute of Molecular Medicine, John Radcliffe Hospital, Oxford, UK.
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41
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Williams TN, Maitland K, Ganczakowski M, Peto TE, Clegg JB, Weatherall DJ, Bowden DK. Red blood cell phenotypes in the alpha + thalassaemias from early childhood to maturity. Br J Haematol 1996; 95:266-72. [PMID: 8904880 DOI: 10.1046/j.1365-2141.1996.d01-1906.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.1] [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] [Indexed: 02/02/2023]
Abstract
The alpha+ thalassaemias are the most common single gene disorders of humans, yet little is known about their haematological characteristics in childhood. Blood samples have been collected randomly from more than 2000 individuals in village communities in Vanuatu in the South West Pacific and analysed for alpha thalassaemia and associated haematological changes. Here we describe the haematological effects of the alpha+ thalassaemias from early childhood through to maturity in this population. Mean cell volume (MCV) and mean cell haemoglobin (MCH) levels in individuals of normal, heterozygous and homozygous genotype differed significantly from one another throughout the entire age range (2P < 0.05). In contrast, haemoglobin levels in heterozygous and homozygous individuals were well maintained throughout development. Adults of normal genotype attain Hb levels which are indistinguishable from Caucasian reference values, a finding made all the more remarkable given the high frequency of clinical malaria in this population. It is clear from these findings that haematological data are valuable in screening for carriers of alpha+ thalassaemia in this population. MCH is clearly the most sensitive discriminator. None of the homozygous adults tested had an MCH of > 27 pg, whereas < 10% of normals had a value of < 27 pg. These data provide reference values for areas in which the alpha+ thalassaemias are common and often confused with iron-deficiency anaemia.
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Affiliation(s)
- T N Williams
- Institute of Molecular Medicine, John Radcliffe Hospital, Oxford
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42
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Maitland K, Williams TN, Bennett S, Newbold CI, Peto TE, Viji J, Timothy R, Clegg JB, Weatherall DJ, Bowden DK. The interaction between Plasmodium falciparum and P. vivax in children on Espiritu Santo island, Vanuatu. Trans R Soc Trop Med Hyg 1996; 90:614-20. [PMID: 9015495 DOI: 10.1016/s0035-9203(96)90406-x] [Citation(s) in RCA: 105] [Impact Index Per Article: 3.8] [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] [Indexed: 02/03/2023] Open
Abstract
Studies of the prevalence and incidence of malaria were conducted in children < 10 years old living in 10 rural villages on the island of Espiritu Santo, Vanuatu, south-west Pacific. Malaria prevalence remained stable at 30% throughout the year but the relative contributions of the 2 major species were highly dependent on season. Plasmodium falciparum predominated in the long wet season (November-May) and P. vivax in the dry season (June-October). Case definitions for malaria, derived using a multiple logistic regression method, showed that parasite densities associated with clinical disease were low; case definitions for P. falciparum (> 1000 parasites/microL in children > 1 year old and > 500 microL in infants) and P. vivax (> 500 parasites/microL at all ages) were both associated with a specificity and sensitivity of > 90%. Like prevalence data, malaria morbidity was highly seasonal; 80% of clinical P. falciparum infections occurred in the wet season and 66% of clinical P. vivax in the dry season. Mixed infections were rare. Malaria was important cause of morbidity with children < 5 years old experiencing 1.3-3.0 episodes of clinical malaria per year and 23% of fevers being attributable to malaria in this age group. Children aged 5-9 years continued to suffer one episode of clinical malaria per year. The peak incidence of P. vivax malaria occurred earlier in life than the peak incidence of P. falciparum malaria. The possible interactions between these 2 parasite species are discussed.
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Affiliation(s)
- K Maitland
- Institute of Molecular Medicine, John Radcliffe Hospital, Oxford, UK
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43
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Williams TN, Maitland K, Bennett S, Ganczakowski M, Peto TE, Newbold CI, Bowden DK, Weatherall DJ, Clegg JB. High incidence of malaria in alpha-thalassaemic children. Nature 1996; 383:522-5. [PMID: 8849722 DOI: 10.1038/383522a0] [Citation(s) in RCA: 203] [Impact Index Per Article: 7.3] [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] [Indexed: 02/02/2023]
Abstract
The alpha+-thalassaemias are the commonest known human genetic disorders, affecting up to 80 per cent of some populations. Although there is good evidence from both epidemiological and clinical studies that these gene frequencies reflect selection by, and protection from, malaria, the mechanism is unknown. We have studied the epidemiology of malaria in childhood on the southwestern Pacific island of Espiritu Santo in Vanuatu and here we report that, paradoxically, both the incidence of uncomplicated malaria and the prevalence of splenomegaly, an index of malaria infection, are significantly higher in young children with alpha+-thalassaemia than in normal children. Furthermore, this effect is most marked in the youngest children and for the non-lethal parasite Plasmodium vivax. The alpha+-thalassaemias may have been selected for their ability beneficially to increase susceptibility to P. vivax, which, by acting as a natural vaccine in this community, induces limited cross-species protection against subsequent severe P. falciparum malaria.
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Affiliation(s)
- T N Williams
- Institute of Molecular Medicine, John Radcliffe Hospital, Headington, Oxford, UK
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Bryan JH, Burwell C, Maitland K, Williams T. Culicine mosquitoes (Diptera: Culicidae) attracted to humans on Espiritu Santo, Vanuatu. Med Vet Entomol 1996; 10:101-102. [PMID: 8834750 DOI: 10.1111/j.1365-2915.1996.tb00089.x] [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] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Affiliation(s)
- J H Bryan
- Tropical Health Program and Department of Entomology, University of Queensland, Australia
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45
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Brindle PM, Maitland K, Williams TN, Ganczakowski ME. A survey for the rare blood group antigen variants, En(a-), Gerbich negative and Duffy negative on Espiritu Santo, Vanuatu in the South Pacific. Hum Hered 1995; 45:211-4. [PMID: 7558053 DOI: 10.1159/000154291] [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: 01/25/2023] Open
Abstract
The people of Vanuatu exhibit several different genetic red cell polymorphisms. Some of these, such as alpha thalassaemia, are thought to have reached a high frequency as a result of selection pressure by malaria. In this study three rare blood group antigen variants, En(a-), Gerbich negative and Duffy negative, which are thought to confer a protective effect against malaria were sought in a sample of 214 (187 in the case of Duffy) from Espiritu Santo, Vanuatu. No individuals bearing these rare variants were found. The original settlers in Vanuatu are thought to have migrated from Papua New Guinea some 5,000 years ago, so it is of interest to note that no individuals were found to be Gerbich negative despite a high frequency in Melanesians living on some coastal parts of Papua New Guinea.
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Affiliation(s)
- P M Brindle
- Faculty of Medicine, University of Bristol, UK
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46
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Williams TN, Maitland K, Foley DH. Malaria sporozoite rates for Anopheles farauti s.s. Laveran (Diptera: culicidae) from Vanuatu. Ann Trop Med Parasitol 1995; 89:305-7. [PMID: 7668922 DOI: 10.1080/00034983.1995.11812956] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
- T N Williams
- Northern District Hospital, Espiritu Santo, Vanuatu
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Ganczakowski M, Bowden DK, Maitland K, Williams TN, O'Shaughnessy D, Viji J, Lucassen A, Clegg JB, Weatherall DJ. Thalassaemia in Vanuatu, south-west Pacific: frequency and haematological phenotypes of young children. Br J Haematol 1995; 89:485-95. [PMID: 7734345 DOI: 10.1111/j.1365-2141.1995.tb08353.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.8] [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] [Indexed: 01/26/2023]
Abstract
The archipelago of Vanuatu situated in the South-West Pacific has a high frequency of alpha + thalassaemia and additionally on some of the islands there is a high frequency of beta thalassaemia. As part of a large cohort study to investigate the clinical effect of thalassaemia on malaria on the islands of Espiritu Santo and Maewo in Vanuatu, the gene frequencies of the thalassaemias were determined and blood counts were performed on a cohort of infants from birth to 3 years. The haematological phenotypes of the different thalassaemic genotypes are compared, providing a detailed description of the clinical manifestations of alpha + thalassaemia during early development. In addition, cross-sectional surveys of the population of the two islands were performed to establish the frequency of thalassaemia and other red cell polymorphisms and their geographical distribution.
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Affiliation(s)
- M Ganczakowski
- Institute of Molecular Medicine, John Radcliffe Hospital, Headington, Oxford, U.K
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