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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Formulation, characterization and cellular toxicity of lipid based drug delivery systems for mefloquin / Chrizaan Helena (nee Slabbert)

Helena (nee Slabbert), Chrizaan January 2011 (has links)
Malaria affects millions of people annually especially in third world countries. Increase in resistance and limited research being conducted adds to the global burden of malaria. Mefloquine, known for unwanted adverse reactions and neurotoxicity, is highly lipophilic and is still used as treatment and prophylaxis. Lipid drug delivery systems are commonly used to increase solubility and efficacy and decrease toxicity. The most generally used lipid drug delivery system is liposomes. The lipid bilayer structure varying in size from 25 nm to 100 μm can entrap both hydrophilic and lipophilic compounds. Similar in structure and size to liposomes, Pheroid™ technology consist of natural fatty acids and is also able to entrap lipophilic and hydrophilic compounds. The aim of this study was to formulate liposomes and Pheroid™ vesicles loaded with mefloquine and evaluate the physiochemical characteristic of the formulations followed by efficacy and toxicity studies. Pheroid™ vesicles and liposomes with and without mefloquine were evaluated in size, morphology, pH and entrapment efficacy during three month accelerated stability testing. Optimization of size determination by flow cytometry lead to accurate determination of size for both Pheroid™ vesicles and liposomes. During the three months stability testing, Pheroid™ vesicles showed a small change in size from 3.07 ± 0.01 μm to approximately 3 μm for all three temperatures. Confocal laser scanning microscopic evaluation of the liposomes showed structures uniform in spherical shape and size. No difference in size or structure between the Pheroid™ vesicles with and without mefloquine were obtained. Significant increase (p=0.027) in size from 6.46 ± 0.01 μm to above 10 μm was observed for liposomes at all the temperatures. Clearly formed lipid bilayer structures were observed on micrographs. With the addition of mefloquine to the liposome formulation, a decrease in the amount of bilayer structures and an increase in oil droplets were found. Entrapment efficacy was determined by firstly separating the entrapped drug from the unentrapped drug utilizing a Sephadex®G50 mini column. This was followed by spectrophotometric evaluation by UV-spectrophotometry at 283 nm. Initial entrapment efficacy of both Pheroid™ vesicles and liposomes was above 60%. An increase in entrapment efficacy was observed for Pheroid™ vesicles. The addition of mefloquine to already formulated Pheroid™ vesicles illustrated entrapment efficacy of 60.14 ± 5.59% after 14 days. Formulations loaded with mefloquine resulted in lower pH values as well as a decrease in pH over time. Optimization of efficacy studies utilizing propidium iodide was necessary due to the similarity in size and shape of the drug delivery systems to erythrocytes. A gating strategy was successfully implemented for the determination of the percentage parasitemia. Efficacy testing of mefloquine loaded in Pheroid™ vesicles and liposomes showed a 186% and 207% decrease in parasitemia levels compared to the control of mefloquine. Toxicity studies conducted include haemolysis and ROS (reactive oxygen species) analysis on erythrocytes as well as cell viability on mouse neuroblastoma cells. Pheroid™ vesicles with and without mefloquine resulted in a dose dependent increase in ROS and haemolysis over time. A dose dependent increase in ROS and haemolysis in both liposome formulations were observed, but to a lesser extent. Mefloquine proved to be neurotoxic with similar results obtained when mefloquine was entrapped in liposomes. Pheroid™ vesicles seem to have neuroprotective properties resulting in higher cell viability. Mefloquine could be entrapped successfully in Pheroid™ vesicles and less in liposomes. Pheroid™ vesicles was more stable over a three months accelerated stability testing with more favourable characteristics. The increase in ROS levels of Pheroid™ vesicles could be responsible for the higher efficacy and haemolytic activity. DL-α-Tocopherol in Pheroid™ vesicles possibly acted as a pro-oxidant due to the presence of iron in the erythrocytes. DL-α-Tocopherol showed possible antioxidant properties in the neurotoxicity evaluation resulting in higher cell viability. Even though liposomes illustrated higher efficacy and little haemolysis and ROS production, no difference in neurotoxicity was observed together with unfavourable properties during stability testing makes this drug delivery system less favourable in comparison to Pheroid™ vesicles. Mefloquine was successfully incorporated into Pheroid™ vesicles resulted in high efficacy and showed possible neuroprotection and therefore makes it an ideal system for treatment of malaria. / Thesis (Ph.D. (Pharmaceutics))--North-West University, Potchefstroom Campus, 2011
12

Sources of preanalytical error in primary health care : implications for patient safety

Söderberg, Johan January 2009 (has links)
Background Venous blood tests constitute an important part in the diagnosis and treatment of patients. However, test results are often viewed as objective values rather than the end result of a complex process. This has clinical importance since most errors arise before the sample reaches the laboratory. Such preanalytical errors affect patient safety and are often due to human mistakes in the collection and handling of the sample. The preanalytical performance of venous blood testing in primary health care, where the majority of the patients contact with care occurs, has not previously been reported. Aims To investigate venous blood sampling practices and the prevalence of haemolysed blood samples in primary health care. Methods A questionnaire investigated the collection and handling of venous blood samples in primary health care centres in two county councils and in two hospital clinical laboratories. Haemolysis index was used to evaluate the prevalence of haemolysed blood samples sent from primary health care centres, nursing homes and a hospital emergency department. Results and discussion The results indicate that recommended preanalytical procedures were not always followed in the surveyed primary health care centres. For example, only 54% reported to always use name and Swedish identification number, and 5% to use photo-ID, the two recommended means for patient identification. Only 12% reported to always label the test tubes prior to blood collection. This increases the possibility of sample mix-up. As few as 6% reported to always allow the patient to rest at least 15 minutes before blood collection, desirable for a correct test result. Only 31% reported to have filed an incident report regarding venous blood sampling, indicating underreporting of incidents in the preanalytical phase. Major differences in the prevalence of haemolysed blood samples were found. For example, samples collected in the primary health care centre with the highest prevalence of haemolysed samples were six times (95% CI 4.0 to 9.2) more often haemolysed compared to the centre with the lowest prevalence. The significant variation in haemolysed samples is likely to reflect varying preanalytical conditions. Conclusions This thesis indicates that the preanalytical procedure in primary health care is associated with an increased risk of errors with consequences for patient safety and care. Monitoring of haemolysis index could be a valuable tool for estimating preanalytical sample quality. Further studies and interventions aimed at the preanalytical phase in primary health care are clearly needed.
13

Improving venous blood specimen collection practices : method development and evaluation of an educational intervention program / Metoder för förbättrad venprovtagning : utvärdering av ett utbildningsprogram

Bölenius, Karin January 2014 (has links)
Background: About 60%–80% of decisions regarding diagnosis and treatment are based on laboratory test results. Low adherence to venous blood specimen collection (VBSC) guidelines may lead to erroneous or delayed test results, causing patient harm and high healthcare costs. Educational intervention programs (EIPs) to update, improve and sustain VBSC practices are seldom evaluated. After testing a self-reported venous blood sampling questionnaire, the overall aim of this thesis was to evaluate the impact of a large-scale EIP on healthcare personnel’s VBSC practices. Methods: The study settings were primary healthcare centres (PHCs) in northern Sweden. Participants were VBSC personnel. Data consisted of a VBSC questionnaire of self-reported practices, records of low-level haemolysis index in serum samples (specimen quality indicator), and interviews reflecting VBSC practices. First, experts on questionnaires and VBSC were consulted, and test-retest statistics were used when testing the VBSC questionnaire for validity and reliability. Thereafter, we evaluated the impact of a short, large-scale EIP with a before-after approach comparing self-reported VBSC questionnaire of two county councils. The personnel of the county councils (n = 61 PHCs) were divided into an intervention group (n = 84) and a corresponding control group (n = 79). In order to test changes in blood specimen quality we monitored haemolysis in serum samples (2008, n = 6652 samples and 2010, n = 6121 samples) from 11 PHCs. Finally, 30 VBSC personnel from 10 PHCs reported their experiences. The interview questions were open-ended with reflective elements and the interviews were analysed by qualitative content analysis. Results: The VBSC questionnaire was found to be valid and could be used to identify risk of errors (near misses) and evaluate the impact of an EIP emphasising VBSC guideline adherence. The intervention group demonstrated several significant improvements in self-reported practices after the EIP, such as information search, patient rest, test request management, patient identification, release of venous stasis, and test tube labelling. The control group showed no significant improvements. In total, PHCs showed minor differences in blood specimen quality. Interviews summarized VBSC personnel experiences in the overall theme: education opened up opportunities for reflection about safety.   Conclusion: This thesis is, to our knowledge, the first to evaluate the impacts of a large-scale EIP on VBSC practices. The VBSC questionnaire and monitoring for low-level haemolysis reflected VBSC practices. The frequently occurring near-miss markers made it possible to compare and benchmark VBSC practices down to the healthcare unit and hospital ward. The short, general EIP opened up opportunities for reflection about safety and improved VBSC practices in PHCs with larger deviations from guidelines. EIPs that provide time for reflection and discussion could improve VBSC further. Directed EIPs focused on specific VBSC flaws might be more effective for some near misses in VBSC practices, while some near misses must be changed at a different level in the system. Clinical relevance: Our results indicate that monitoring and counteracting the near misses in VBSC practices is a well-functioning preventive action. We propose that the VBSC monitoring instruments (VBSC questionnaire & haemolysis index) we used and the EIP strategy proposed should be tested in additional countries with different healthcare settings. It is suggested that a national program intended to identify near misses and prevent VBSC errors be developed in the healthcare system. General e-learning programs may be cheaper than, and as effective as, the EIP program and may be performed everywhere and any time. Systematic planning, useful for reflection and with focus on the specific elements in a skill, together with VBSC guidelines, could probably increase improvements. Our studies have led to deeper and extended knowledge of the impact of an EIP on VBSC practices. Our results can be used when considering future VBSC practice interventions. Using a model for practical skills in nursing to describe VBSC in a more holistic and less technical way might highlight VBSC as a practical nursing skill. / Bakgrund: Av kliniska beslut angående diagnostik och behandling baseras 60%–80% på laboratorieresultat. Därför är det helt nödvändigt att laboratorieresultat är tillförlitliga. Låg följsamhet till provtagnings anvisningar kan leda till felaktiga och fördröjda analysresultat, förorsaka skada och lidande för patienter och utgöra en stor kostnad för hälso- och sjukvården. Felaktiga provsvar beror till stor del på felaktig provtagning och provhantering och går oftast att undvika. Interventioner som avser att uppdatera och säkra korrekt venprovtagning kan leda till förbättringar men genomförda interventioner har sällan utvärderats. Efter att en enkät för självrapporterad venprovtagning testats för validitet och reliabilitet genomfördes ett omfattande interventionsprogram som utvärderades med hjälp av den testade enkäten och andra utvärderingsmått. Det övergripande syftet var att utvärdera i vilken utsträckning interventionsprogrammet påverkade provtagande personals praktiska utförande av venprovtagning. Metoder: Studierna i denna avhandling omfattade provtagande personal vid hälsocentraler i norra Sverige. För datainsamling användes en enkät som mäter självrapporterad venprovtagning, förekomst av låggradig hemolys (indikator på blodprovets kvalitet) och intervjuer. Initialt testades enkätens förmåga att mäta vad som avsetts (validitet) och testades enkätens förmåga att vid upprepade mätningar vara tillräckligt stabil (reliabilitet) för att användas i interventionsstudier. Därefter utvärderades ett kort men storskaligt interventionsprogram i preanalys inkluderande venprovtagning med före och efter mätningar. Vi jämförde provtagande personal från två landsting vid 61 hälsocentraler. Landstingens personal delades upp i en interventionsgrupp (n=84) och en motsvarande kontrollgrupp (n = 79). För att mäta kvaliteten av blodproverna extraherades uppgifter om hemolys i serumprover (2008, n = 6652 blodprov) och (2010, n = 6121 blodprov) från elva hälsocentraler i ett landsting. Slutligen, intervjuades 30 provtagande personal från 10 hälsocentraler efter att de deltagit i interventionsprogrammet. Intervjuerna var öppna och genererade korta berättelser och analyserades med innehållsanalys. Resultat: Venprovtagningsenkäten befanns vara valid och kan användas för att utvärdera personalens följsamhet till provtagningsanvisningar i venprovtagning och identifiera riskhändelser. Interventionsgruppen visade flera signifikanta förbättringar i självrapporterat utförande av venprovtagning såsom förbättrad informationssökning, vila inför provtagning, remissförfarande, kontroll av patientidentitet, användning av stas och etikettering av provrör. Kontrollgrupen visade inga signifikanta förbättringar. Blodprovskvaliteten visade små skillnader. Provtagande personals erfarenheter från intervjuerna sammanfattades i ett övergripande tema; utbildningsinsatsen öppnade upp möjligheter för reflektion om säkerhet.   Slutsats: Avhandlingen är så vitt vi vet den första att utvärdera effekten av ett storskaligt interventionsprogram med hjälp av självrapporterat utförande av venprovtagning och blodprovers kvalitet (låggradig hemolys). Med dessa metoder ökar andelen riskhändelser så att jämförelser kunde göras även på enhetsnivå och avdelningsnivå. Utbildningsprogrammet öppnade upp för reflektioner om säkerhet och förbättrade utförande av venprovtagning vid enheter med större brister. Utbildningsprogram som öppnar upp för reflektion och diskussion kan leda till ökad patientsäkerhet i hälso- och sjukvården. Trots utfallet av resultaten, är riktade utbildningsinsatser för sjukvårdsenheter som uppvisar specifika brister troligtvis mer effektiva än breda utbildningsinsatser. Klinisk betydelse: Interventionsprogram avseende preanalys och venös provtagning förbättrade personalens praktiska utförande. Monitorering av och åtgärder för att minska riskhändelser är väl fungerande preventiva åtgärder. Instrumenten (självrapporterande enkät och hemolys) bör också testas i andra kontexter inom hälso- och sjukvården. Ett externt nationellt program för att identifiera och förebygga riskhändelser bör utvecklas i hälso- och sjukvården. Interventioner i form av e-lärande kan då vara ett alternativ som är billigt och effektivt. Dessutom kan systematisk planering och genomförande med fokus på reflektion av specifika delar i en färdighet vara effektivt för att uppnå förbättringar. Våra studier har bidragit till en djupare och utökad kunskap om effekten av ett interventionsprogram på utförande av venprovtagning. Resultaten kan användas vid framtida planering av utbildningsinsatser. Modeller för praktiskt färdighetsutövande inom omvårdnad kan beskriva venprovtagning ur ett helhetsperspektiv och synliggöra venprovtagning som en viktig praktisk färdighet inom omvårdnad. / Preanalys

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