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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.

Endotoxin recognition by the innate immune receptor CD14 is a critical part of the innate immune system’s early detection and activation of the inflammatory response during microbial invasion. The differential recognition and high affinity binding of endotoxins from gram-negative and gram-positive bacteria is performed by the innate immune receptor CD14. Upon endotoxin binding, CD14 transfers the specific endotoxins to a Toll-like receptor signaling complex, which is responsible for initiating the intracellular signaling cascade. In the presence of overwhelming infection, the effects of CD14 lead to the over-activation of the inflammatory response, which results in the life threatening condition known as sepsis. Preparation of a 15N isotopically labeled truncated version of soluble CD14, using Pichia pastoris, allowed direct structural observation of the binding interaction between CD14 and two endotoxin ligands, lipopolysaccharide (LPS) and lipoteichoic acid (LTA), from gram-negative and gram-positive bacteria, respectively using solution NMR spectroscopy. These studies revealed that CD14 uses both a common set of residues, and endotoxin specific subsets of residues, to bind LPS and LTA. To further investigate the structural features of each endotoxin recognized by CD14, 13C 15N isotopically labeled Kdo2–Lipid A, a fully active chemically defined gram-negative endotoxin, and LTA lipid anchor, the minimal unit of LTA, were produced. This allowed detailed NMR spectral mapping of these agonist ligands bound to sCD14 which identified, for the first time, structural regions and features in each that are strongly affected during complex formation with sCD14. Additionally, the presence of differential dynamic behavior was seen in both CD14 and the ligands upon complexation. This behavior suggests a likely role for dynamics in the mechanism of pattern recognition by CD14, which uses the dynamic ability of specific residue combinations to differentially affect endotoxin binding. Using NMR, the dynamic behavior of CD14 was further investigated using temperature and pH-dependence studies of isotopically labeled CD14. These studies clearly demonstrated the presence of multiple conformations for several residues, and may provide a possible explanation for the broad specificity of ligand binding by CD14. In addition, the spin-labeling of isotopically labeled lipid A enabled the collection of intermolecular distances on CD14 bound lipid A.

Acute quadriplegic myopathy (AQM), or critical illness myopathy, is a common debilitating acquired disorder in critically ill intensive care unit (ICU) patients characterized by generalized muscle wasting and weakness of limb and trunk muscles. A preferential loss of the thick filament protein myosin is considered pathognomonic of this disorder, but the myosin loss is observed relatively late during the disease progression. In attempt to explore the potential role of factors considered triggering AQM in sedated mechanically ventilated (MV) ICU patients, we have studied the early effects, prior to the myosin loss, of neuromuscular blockade (NMB), corticosteroids (CS) and sepsis separate or in combination in a porcine experimental ICU model. Specific interest has been focused on skeletal muscle gene/protein expression and regulation of muscle contraction at the muscle fiber level. This project aims at improving our understanding of the molecular mechanisms underlying muscle specific differences in response to the ICU intervention and the role played by the different triggering factors. The sparing of masticatory muscle fiber function was coupled to an up-regulation of heat shock protein genes and down-regulation of myostatin are suggested to be key factors in the relative sparing of masticatory muscles. Up-regulation of chemokine activity genes and down-regulation of heat shock protein genes play a significant role in the limb muscle dysfunction associated with sepsis. The effects of corticosteroids in the development of limb muscle weakness reveals up-regulation of kinase activity and transcriptional regulation genes and the down-regulation of heat shock protein, sarcomeric, cytoskeletal and oxidative stress responsive genes. In contrast to limb and craniofacial muscles, the respiratory diaphragm muscle responded differently to the different triggering factors. MV itself appears to play a major role for the diaphragm muscle dysfunction. By targeting these genes, future experiments can give an insight into the development of innovative treatments expected at protecting muscle mass and function in critically ill ICU patients.

Diss. (sammanfattning) Stockholm : Karol. inst., 2003. / Härtill 5 uppsatser.

Ulm, Univ., Diss., 2001.

München, Techn. Univ., Diss., 2004.

Polimorfismos em genes codificando proteínas envolvidas no reconhecimento de microrganismos e na resposta imune contra patógenos podem influenciar na quantidade ou na função da proteína produzida em resposta ao estímulo bacteriano. Existem evidências de que alguns destes polimorfismos genéticos modificam a resposta do paciente à sepse. No presente estudo, foram estudados polimorfismos presentes em genes que, sabidamente ou supostamente, apresentam um efeito biológico importante na sepse com o objetivo de identificar marcadores associados com a sepse e com a evolução clínica favorável ou com a morte. Entre esses polimorfismos estão aqueles presentes nos genes TNF_, TNFß, IL1RN, HSP70, IL6, IL10, CD14, TLR4, TLR2. As técnicas utilizadas compreenderam PCR em tempo real usando sondas com marcação fluorescente (VIC e FAM), PCR usual, digestão com enzimas de restrição e eletroforese. Os 97 pacientes com sepse, sepse grave e choque séptico estudados foram tratados na UTI do Hospital de Base de São José do Rio Preto. Também foram estudadas amostras de 207 indivíduos saudáveis coletadas no Hemocentro do mesmo hospital. Os polimorfismos IL6-597, HSP70-2 e o haplótipo do gene IL6 apresentaram valores estatisticamente significativos. Os dados obtidos sugerem que os polimorfismos IL6-597 e o haplótipo IL6 -174/-1753/- 2954/-597 estão associados com a evolução clínica da sepse, enquanto o polimorfismo do gene HSP70 está associado com bacteremia. A associação de polimorfismos em pacientes com sepse deverá ser avaliada em um maior número de pacientes no Brasil para ampliar nosso conhecimento sobre variantes genéticas e seus efeitos no curso clínico da sepse. Associações de polimorfismos com sepse e susceptibilidade a infecção podem ser no futuro utilizadas como marcadores moleculares para prognóstico. / Polymorphisms in genes codifying proteins involved in the recognition of microorganisms and in the answer of pathogens can influence the amount or the function of the protein produced in response to bacterial incentive. There are evidences that some of these genetic polymorphisms modify the patient\'s answer to sepsis. In the present study, we studied polymorphisms present in genes that, knowingly or supposedly, has an important biological effect in sepsis with the objective of identifying markers associated with sepsis and with the favorable clinical evolution or with the death. Among those polymorphisms they are those presents in the genes TNF, TNF, IL1RN, HSP70, IL6, IL10, CD14, TLR4, TLR2. The used techniques were Real time PCR using fluorescent probes (VIC and FAM), PCR, digestion with restriction enzymes and electrophoresis. The 97 patients with sepsis, severe sepsis and septic shock studied were those treated in INTENSIVE CARE UNIT of the Base´s Hospital of Sao Jose do Rio Preto. And 207 healthy individuals\' samples were collected in Hemocentro of the same hospital. The polymorphisms of the genes IL6-597, HSP70-2 and the haplotype of the gene IL6 presented estatistical significant values. The polymorphism IL6-597 and the haplotype IL6 - 174/-1753/-2954/-597 can be associated with the clinical evolution of sepsis, while the polymorphism of the gene HSP 70 can be associated with bacteremia. The association of polymorphisms in patients with sepsis will have to be evaluated in bigger samples of patients in Brazil to extend our knowledge on genetic variants and its effect in the clinical course of sepsis. Associations of polymorphisms with sepsis and susceptibility to infection can be in the future used as molecular marker for prognostic.

Made available in DSpace on 2015-05-14T12:47:11Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 1045835 bytes, checksum: e46f94704730d71206de4c90e9160b1a (MD5) Previous issue date: 2012-02-27 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The Intensive Care Unit (ICU) environments are specialized in assisting the patient severely ill. The development of these units drastically reduced the hospital mortality rate, however, the complex procedures on their patients favors the emergence of serious infections such as sepsis, which predisposes to death. The present study aimed to provide a probabilistic decision model for the early diagnosis of sepsis. To this end, we analyzed the data contained in the records of 100 patients hospitalized in a general ICU of a public hospital in the state of Paraíba, in the period from March to September 2011. The information was recorded in a proper instrument made by the researcher being studied variables: age, gender, initial diagnosis of the participants, the minimum and maximum axillary temperature, heart rate and respiratory rate, partial pressure of oxygen and carbon dioxide, serum lactate , potassium, sodium, total leukocyte count, segmented rods and, among others. We used binary logistic regression to determine the prediction model. Data analysis was performed using SPSS version 19.0. The findings showed that 63% of study participants were male, with a mean age of 62.5 years. Explanatory variables were considered: axillary temperature minimum, maximum axillary temperature, partial pressure of carbon dioxide, lactate, leukocyte count and the number of rods. ROC curve was possible to identify the optimal cutoff point to classify individuals according to the presence or absence of disease, which contributed to the making of the rule of decision for the early diagnosis of sepsis. Was performed to compare the degree of agreement between blood culture result considered the gold standard for diagnosis of infection and the model presented in this study using the Kappa coefficient, obtained a percentage of agreement of 0.93 is considered excellent. Despite the unprecedented nature of the research, proved to be early detection of sepsis with the adoption of statistical models as presented, however, further studies with different populations of ICUs should be performed in order to provide a better sample, making the results found reproducible in different clinical situations daily. / As Unidades de Terapia Intensiva (UTI) são ambientes especializados na assistência ao paciente gravemente enfermo. O desenvolvimento dessas unidades reduziu drasticamente a taxa de mortalidade hospitalar, contudo, a realização de procedimentos complexos em seus pacientes favorece o surgimento de infecções graves como a sepse, o que predispõe ao óbito. O presente estudo teve como objetivo fornecer um modelo de decisão probabilístico para o diagnóstico precoce da sepse. Para tanto, foram analisados os dados contidos nos prontuários de 100 indivíduos internados em uma UTI geral de um hospital público do interior do estado da Paraíba, no período de março a setembro de 2011. As informações foram registradas em instrumento próprio confeccionado pelo pesquisador, sendo estudadas as variáveis: idade, gênero, diagnóstico inicial dos participantes, a temperatura axilar mínima e máxima, frequência cardíaca e respiratória, pressão parcial de oxigênio e de gás carbônico, nível sérico de lactato, potássio, sódio, contagem total de leucócitos, bastonetes e segmentados, dentre outras. Utilizou-se a regressão logística binária para determinação do modelo de predição. A análise dos dados foi realizada utilizando-se o software SPSS versão 19.0. Os achados demonstraram que 63% dos participantes do estudo eram do gênero masculino, apresentando uma idade média de 62,5 anos. Foram consideradas como variáveis explicatórias: a temperatura axilar mínima, a temperatura axilar máxima, a pressão parcial de gás carbônico, o lactato, a contagem de leucócitos e o número de bastonetes. Através da curva ROC foi possível identificar o ponto de corte ideal para classificação dos indivíduos quanto à presença ou ausência da doença, o que contribuiu para confecção da regra de tomada de decisão para o diagnóstico precoce da sepse. Realizou-se a comparação do grau de concordância entre o resultado da hemocultura considerado como padrão-ouro para o diagnóstico da infecção e o modelo apresentado no estudo utilizando-se o coeficiente Kappa, sendo obtido um percentual de concordância de 0,93 que é considerado como excelente. Apesar do caráter inédito da pesquisa, demonstrou-se ser possível a detecção precoce da sepse com a adoção de modelos estatísticos como o apresentado, entretanto, novos estudos com populações de diferentes UTIs devem ser realizados a fim de prover uma casuística melhor, tornando os resultados encontrados reproduzíveis em diferentes situações clínicas diárias.

Proteomics is the large-scale study of proteins, particularly their structures and functions. Proteomics has been utilized in medicine for investigation of disease mechanisms and biomarker discovery. Instrumental methods cover sample preparation, protein and peptide separation and mass spectrometry. At present, there is no proteomic method that can be used as universal for every sample. Analytical methods need to be adapted and optimized for certain samples. The aim of this work was to create methodic procedures and to interpret results of experimental and clinical research. The first part of the thesis includes experiments utilizing proteomics to study changes in the plasma proteome clinically relevant porcine model of sepsis-induced peritonitis. Proteomic analyzes were also starting methodological strategies in experiments aimed at kidney physiology and pathophysiology of acute kidney injury during sepsis. Renal biopsies were analyzed in order to study the time course of proteome changes caused by sepsis and surgery. The second part of the thesis contains experiments studying biocompatibility. A method for elution of proteins interacting with adsorbents used in extracorporeal liver support system and with hemodialyzer capillaries was prepared. Analysis of proteins adsorbed to polysulfone...