Cells often exist in heterogeneous mixtures. Density provides a property to separate several types of cells from the mixed sample in which they originate. Density-based separation methods provide a standard method to quickly separate or enrich specific populations of cells, such as lymphocytes from whole blood. This dissertation explores the use of aqueous multiphase systems (AMPS) as self-forming step-gradients in density for the separation of cells. AMPS were first discovered over a hundred years ago as aqueous two-phase systems. Density as a tool to separate cells is at least as old. Despite this long history, the work in this thesis is the first work to use AMPS to perform density-based separations on cells. This combination provides a powerful technique to separate cells and enable new testing at the point-of-care. Chapter 1 provides a short overview of aqueous multiphase systems and density-based separations of cells. Chapter 2 describes the process of taking technology, including AMPS, from a demonstration in a laboratory to a large scale evaluation in a field setting. In Chapter 3 and Appendix I, AMPS provide a means to enrich reticulocytes from whole blood as a means to grow malaria parasites. Chapter 4 and Appendix II describe the development and proof-of-prinicple of a density-based diagnostic test for sickle cell disease (SCD) using AMPS. Chapter 5 and Appendix III detail the results of a large scale field evaluation of a rapid test for SCD using AMPS in Zambia. Demonstrations of AMPS for density- and size-based separations are provided in Appendices IV and V. Appendix VI demonstrates the general usefulness of density to separate crystal polymorphs with another density-based separation method: magnetic levitation in a paramagnetic fluid. Beyond density, novel combinations of technology, such as electrochemistry and telecommunications provide opportunities for enabling global health (Appendix VII). / Engineering and Applied Sciences

No description available.

In Sweden, lowest acceptable haemoglobin levels in blood donators are 125g/L for women and 135g/L for men for a test sample taken in the beginning of the blood donation. Levels, which are 10g/L lower, are accepted if the sample is taken after the blood donation. Earlier studies show that the haemoglobin level decreases for a person that is lying down. The two aims of this study were to examine how much the haemoglobin levels change during blood donation and to examine if the photometrical instrument Pronto-7TM shows equivalent results to that of the established method Cell-Dyn Sapphire. In the study, 120 blood donors participated. Blood samples were taken in the beginning and in the end of the donation. Analyses by Pronto-7TM were done before and after the donation. The haemoglobin level decreased significantly during the blood donation. The difference was in mean value 5,9g/L according to Cell-Dyn Sapphire. The decrease was significantly less than 10g/L. The Pronto-7TM gave levels that were 1,6g/L higher than Cell-Dyn Sapphire in mean and the standard deviation was higher for Pronto-7TM than for Cell-Dyn Sapphire. In conclusion, the decrease of the haemoglobin levels was significantly less than the expected difference 10g/L. Pronto-7TM gives results that differs a little from the results of the established method.

Introduction: No protocol for assessing ultrasound imaging skill has been validated. We sought to develop and validate an assessment protocol for ultrasound imaging for the Focused Assessment with Sonography for Trauma. Methods: Our assessment tool consisted of task checklists, a global rating scale, and hand-motion analysis and was developed by a modified Delphi technique. Novice and expert cohorts were recruited to perform a FAST exam on a volunteer for assessment under the protocol. Results: Experts scored higher on static image acquisition (11.58 of 16 versus 6.63, p<0.0001), dynamic image acquisition (17.21 of 24 versus 11.08, p=0.0005), and our global rating scale (29.79 of 40 versus 18.42, p<0.0001); experts used fewer movements (263.0 movements versus 452.4, p=0.0216) and a shorter path length than novices (60.097 m versus 32.777 m, p=0.0041). Conclusion: Our protocol for assessing ultrasound imaging skill has criterion validity in assessing expertise and may lead to improvements to training and credentialing programs.

The clinical evaluation of people with possible myocardial infarction (MI) is often limited by atypical symptoms and inconclusive initial electrocardiograms. A recent consensus from the American College of Cardiology has redefined acute MI to include cardiac markers as central to diagnosis. To address this clinical need, a sensitive microfluidic surface-enhanced Raman spectroscopy (SERS) nanochannel-based optical device is being developed for ultimate use as a point-of-care device for the simultaneous measurement of MI blood biomarkers. The device can provide enhancements of the Raman signal of the analyte measured of up to 1013 using a mechanical aggregation technique at the interface of nanofluidic structures enabling repeatable SERS measurements. Specifically in this research iterations of a sensitive, low volume SERS platform technology were designed that provided quantitative information across a specific range. With the SERS platforms studied, not only were SERS enhancements of up to 1013 achieved but also imprecision values of less than 10% across the 10-50 pM range using a ratiometric approach and qualitative detection down to 100 aM was achieved. Beyond assessment of SERS substrates, assay designs were investigated and characterized including, label-free techniques and competitive immunoassay formats. Lastly, detecting the SERS signal of multiplexed reporter molecules was investigated. By identifying the analyte and assay constraints the design and optimization of future assays will be aided using this SERS platform technology.

Point-of-care testing (POCT) devices have received increasing attention because of their potential to address the urgent need for quick and accurate diagnostic tools, especially in areas of personal care and clinical medicine. They offer several benefits over current diagnostic systems, including rapid diagnostic results in comparison to microbial cultures, simple interpretation of results, portability, and requiring no specialised laboratory equipment or technical training to operate. These are essential for diagnosing critical illnesses, such as sepsis, in areas of poor healthcare infrastructure. Sepsis, an innate physiological response to infection, is a growing problem worldwide with high associated costs and mortality rates, and affects a wide range of patients including neonates, infants, the elderly, and immunocompromised individuals. A literature review of the biomarkers of sepsis and the currently available diagnostic systems indicates the need for a biosensor capable of meeting the requirements of designing POCT systems and achieving detection of low concentrations of biomarkers. To meet these demands, two significant contributions to developing POCT platforms have been achieved and described in this thesis, including: 1) development of a colorimetric, magnetically separable biosensor that can be easily fabricated and demonstrates an easily identifiable colour response upon analyte detection, as well as the ability to capture and detection target biomarkers at low concentrations from complex solutions; and 2) tuning of the biosensor’s colorimetric response to achieve low detection limits, as well as demonstration of the versatility of the biosensor for sensing different target analytes. The developed biosensor in this work combines colour responsive polydiacetylenes and superparamagnetic iron oxide for the first time to achieve a biosensor capable of meeting these demands. The sensors exhibit identifiable colour responses to biomolecule detection, capture of a target analyte from complex solutions, sensing of different target analytes, a lower detection limit of 0.01 mg/mL, and rapid separation from solution with a common magnet. This work has been a significant demonstration of the capabilities of this biosensor as a new platform for POCT systems to diagnosis sepsis, and potentially other sensing applications.

Biological/biochemistry analyses traditionally require bulky instruments and a great amount of volume of biological/chemical agents, and many procedures have to be performed in certain locations such as medical centers or research institutions. These limitations usually include time delay in testing. The delays may be critical for some aspects such as disease prevention or patient treatment. One solution to this issue is the realization of point-of-care (POC) testings for patients, a domain in public health, meaning that health cares are provided near the sites of patients using well-designed and portable medical devices. Transportation of samples between local and central institutions can therefore be reduced, facilitating early and fast diagnosis. A closely related topic in engineering, lab-on-a-chip (LOC), has been discussed and practiced in recent years. LOC emphasizes integrating several functions of laboratory processes in a small portable device and performing analysis using only a very small amount of sample volume, to achieve low-cost and rapid analysis. From an engineer's point of view, LOC is the strategy to practice the idea of POC testing. This dissertation aimed at exploring the POC potentials of porous membrane-base LOC devices, which can be used to simplify traditional and standard laboratory procedures. In this study, three LOC prototypes are shown and discussed. First the protein sensor incorporating with silica nanofiber membrane, which has shown 32 times more improvement of sensitivity than a conventional technique and a much shorter detection time; secondly the bacteria filter chip that uses a sandwiched aluminum oxide membrane to stabilize the bacteria and monitor the efficacy of antibiotics, which has reduced the test time from 1 day of the traditional methods to 1 hour; the third is the sensor combining microfluidics and silica nanofiber membrane to realize Surface Enhanced Raman Spectroscopy on bio-molecules, which has enhancement factor 10^9 and detection limit down to nanomolar, but simple manufacturing procedures and reduced fabrication cost. These results show the porous-base membrane LOC devices may have potentials in improving and replacing traditional detection methods and eventually be used in POC applications.

Project (M.S.)--Brigham Young University. Dept. of Statistics, 2007. / Includes bibliographical references (p. 60-61).

Thesis (Ph. D.)--University of Washington, 2007. / Vita. Includes bibliographical references (leaves 228-245).

Thesis (MEng)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: South Africa has a severe HIV (human immunodeficiency virus) burden and the management of the disease is a priority, especially in the public healthcare sector. One element of managing the disease, is determining when to initiate an HIV positive individual onto anti-retroviral therapy (ART), a treatment that the patient will remain on for the remainder of their lifetime. For the majority of HIV positive individuals in the country, this decision is governed by the results of a CD4 (cluster of differentiation 4) test that is performed at set time intervals from the time that the patient is diagnosed with HIV until the patient is initiated onto ART. A device for CD4 measurement at the point of care (POC), the Alere PIMA™, has recently become commercially available. This has prompted a need to evaluate whether CD4 testing at the POC (i.e. at the patient serving healthcare facility) should be incorporated into the South African public healthcare sector's HIV diagnostic service provision model. One challenge associated with the management of HIV in the country is the relatively large percentage of patients that are lost to follow-up at various points in the HIV treatment process. There is extensive evidence that testing CD4 levels at the POC (rather than in a laboratory, as is the current practice) reduces the percentage of patients that are lost to follow-up before being initiated onto ART. Therefore, though POC CD4 testing is more expensive than laboratory-based CD4 testing, the use of this technology in South Africa should be investigated for its potential to positively influence health outcomes. In this research, a multi-objective location science model is used to generate scenarios for the provision of CD4 testing capability. For each scenario, CD4 testing provision at 3 279 ART initiation facilities is considered. For each facility, either (i) a POC device is placed at the site; or (ii) the site's testing workload is referred to one of the 61 CD4 laboratories in the country. To develop this model, the characteristics of eight basic facility location models are compared to the attributes of the real-world problem in order to select the most suitable one for application. The selected model's objective, assumptions and inputs are adjusted in order to adequately model the realworld problem. The model is solved using the cross-entropy method for multi-objective optimisation and the results are verified using a commercial algorithm. Nine scenarios are selected from the acquired Pareto set for detailed presentation. In addition, details on the status quo as well as a scenario where POC testing is used as widely as possible are also presented. These scenarios are selected to provide decision-makers with information on the range of options that should be considered, from no or very limited use to widespread use of POC testing. Arguably the most valuable contribution of this research is to provide an indication of the optimal trade-off points between an improved healthcare outcome due to POC CD4 testing and increased healthcare spending on POC CD4 testing in the South African public healthcare context. This research also contributes to the location science literature and the metaheuristic literature. / AFRIKAANSE OPSOMMING: Suid-Afrika gaan gebuk onder `n swaar MIV- (menslike-immuniteitsgebreksvirus-) las en die bestuur van die siekte is `n prioriteit, veral in die openbare gesondheidsorgsektor. Een element in die bestuur van die siekte is om te bepaal wanneer `n MIV-positiewe individu met antiretrovirale- (ARV-)behandeling behoort te begin, waarop pasiënte dan vir die res van hul lewens bly. Vir die meeste MIV-positiewe individue in die land word hierdie besluit bepaal deur die uitslae van `n CD4- (cluster of differentiation 4-)toets wat met vasgestelde tussenposes uitgevoer word vandat die pasiënt met MIV gediagnoseer word totdat hy of sy met ARV-behandeling begin. `n Toestel vir CD4-meting by die punt van sorg (\POC"), die Alere PIMA™, is onlangs kommersieel beskikbaar gestel. Dit het `n behoefte laat ontstaan om te bepaal of CD4-toetsing by die POC (met ander woorde, by die gesondheidsorgfasiliteit waar die pasiënt bedien word) by die MIV-diagnostiese diensleweringsmodel van die Suid-Afrikaanse openbare gesondheidsorgsektor ingesluit behoort te word. Een uitdaging met betrekking tot MIV-bestuur in die land is die betreklik groot persentasie pasiënte wat verlore gaan vir nasorg in die verskillende stadiums van die MIV-behandelingsproses. Heelwat bewyse dui daarop dat die toetsing van CD4-vlakke by die POC (eerder as in `n laboratorium, soos wat tans die praktyk is) die persentasie pasiënte wat verlore gaan vir nasorg voordat hulle met ARV-behandeling kan begin, verminder. Daarom, hoewel CD4-toetsing by die POC duurder is as toetsing in `n laboratorium, behoort die gebruik van hierdie tegnologie in Suid-Afrika ondersoek te word. In hierdie studie is `n meerdoelige liggingswetenskapmodel gebruik om scenario's vir die voorsiening van CD4-toetsvermoë te skep. Vir elke scenario word CD4-toetsvermoë by 3 279 ARV-inisiasie fasiliteite oorweeg. Vir elke fasiliteit word toetsvermoë verskaf deur (i) die plasing van POC-toestelle by die fasiliteit, of (ii) verwysing vir laboratoriumgebaseerde toetsing by een van die 61 CD4-laboratoriums in die land. Die kenmerke van agt basiese fasiliteitsliggingsmodelle is met die kenmerke van die werklike probleem vergelyk om die mees geskikte model vir toepassing op die werklike probleem te bepaal. Die doelwitte, aannames en insette van die gekose model is daarna aangepas om die werklike probleem voldoende te modelleer. Die model is opgelos met behulp van die kruis-entropie-metode vir meerdoelige optimering, waarna die resultate deur middel van `n kommersiële algoritme bevestig is. Nege scenario's uit die verworwe Pareto-stel word uitvoerig aangebied. Daarbenewens beskryf die studieresultate die besonderhede van die status quo sowel as `n scenario waar POC-toetsing so wyd moontlik gebruik word. Hierdie scenario's word aangebied om besluitnemers van inligting te voorsien oor die verskeidenheid moontlikhede wat oorweeg kan word, wat wissel van geen of baie beperkte tot wydverspreide gebruik van POC-toetsing. Die mees beduidende bydrae van hierdie navorsing is stellig dat dit `n aanduiding bied van die optimale kompromie tussen `n verbeterde gesondheidsorguitkoms weens CD4-toetsing by die POC, en verhoogde gesondheidsorgbesteding aan CD4-toetsing by die POC, in die konteks van Suid-Afrikaanse openbare gesondheidsorg. Die navorsing dra ook by tot die ligingswetenskapliteratuur sowel as tot die metaheuristiekliteratuur.