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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.
591

"Avaliação da procalcitonina como marcador de sepse e de choque séptico em pacientes pediátricos" / Evaluation of procalcitonin and C reactive protein as a sepsis marker in pediatric patients

Ronaldo Arkader 09 February 2004 (has links)
Sepse bacteriana é a maior causa de morbimortalidade na faixa etária pediátrica e neonatal. A detecção precoce do quadro séptico é difícil, devido os sinais iniciais da doença serem inespecíficos. A possibilidade da existência de exame laboratorial capaz de identificar precocemente quadros sépticos melhoraria o prognóstico desses pacientes. Várias proteínas de fase aguda foram estudadas como marcadores de infecção sendo a proteína C reativa (PCR) a mais utilizada. A procalcitonina (PCT), um pró-hormônio, encontra-se elevado precocemente em quadros sépticos em crianças e adultos. Estudo prospectivo com 14 crianças submetidas à cirurgia cardíaca com circulação extra-corpórea (CEC), com dosagens seriadas de procalcitonina e proteína C reativa, serviram como modelo de resposta inflamatória sistêmica sem infecção com dosagens antes da CEC, após a CEC no primeiro, segundo e terceiro dia após cirurgia, enquanto 14 crianças com sepse/choque séptico dosagens seriadas de PCT e PCR foram obtidas sequencialmente antes do tratamento antibioticoterápico e a cada dia até o terceiro dia. Em crianças sépticas a PCT demonstrou ser superior a PCR como marcador de sepse assim como para diferenciar quadros inflamatórios sistêmicos. / Bacterial sepsis is a major cause of morbidity and mortality in neonates and children. Early detection of bacterial sepsis is difficult because the first signs of this disease may be minimal or nonspecific. The availability of a laboratory test to accurately and rapidly identify septic neonates and children would be of great value in improving the outcome of these patients. Several acute-phase proteins have been used for the diagnosis of bacterial sepsis and C reactive protein (CRP) is the usual marker. It has been reported that the concentration of procalcitonin (PCT), a pro-hormone, is markedly higher in children and adults with sepsis. In a prospective study, 14 children were enrolled after cardiac surgery with cardiopulmonary bypass (CPB), these group represent the non infected children with inflammatory response. Blood samples were obtained before CPB, after CPB, on the first, second and third day after surgery. Another group with 14 children with sepsis or septic shock were enrolled, and blood samples were obtained before antibiotic start, on the first, second and third days. In septic children PCT concentration is a better diagnostic marker of sepsis and to differentiate inflammatory response than CRP.
592

X-ray diffraction studies of shock compressed bismuth using X-ray free electron lasers

Gorman, Martin Gerard January 2016 (has links)
The ability to diagnose the structure of a material at extreme conditions of high-pressure and high-temperature is fundamental to understanding its behaviour, especially since it was found that materials will adopt complex crystal structures at pressures in the Terapascal regime (1TPa). Static compression, using the diamond anvil cell coupled with synchrotron radiation has to date been the primary method for structural studies of materials at high pressure. However, dynamic compression is the only method capable of reaching pressures comparable to the conditions found in the interior of newly discovered exo-planets and gas giants where such exotic high-pressure behaviour is predicted to be commonplace among materials. While generating extreme conditions using shock compression has become a mature science, it has proved a considerable experimental challenge to directly observe and study such phase transformations that have been observed using static studies due to the lack of sufficiently bright X-ray sources. However, the commissioning of new 4th generation light sources known as free electron lasers now provide stable, ultrafast pulses of X-rays of unprecedented brightness allowing in situ structural studies of shock compressed materials and their phase transformation kinetics in unprecedented detail. Bismuth, with its highly complex phase diagram at modest pressures and temperatures, has been one of the most studied systems using both static and dynamic compression. Despite this, there has been no structural characterisation of the phases observed on shock compression and it is therefore the ideal candidate for the first structural studies using X-ray radiation from a free electron laser. Here, bismuth was shock compressed with an optical laser and probed in situ with X-ray radiation from a free electron laser. The evolution of the crystal structure (or lack there of) during compression and shock release are documented by taking snapshots of successive experiments, delayed in time. The melting of Bi on release from Bi-V was studied, with precise time scans showing the pressure releasing from high-pressure Bi-V phase until the melt curve is reached off-Hugoniot. Remarkable agreement with the equilibrium melt curve is found and the promise of this technique has for future off-Hugoniot melt curve studies at extreme conditions is discussed. In addition, shock melting studies of Bi were performed. The high-pressure Bi - V phase is observed to melt along the Hugoniot where melting is unambiguously identified with the emergence of a broad liquid-scattering signature. These measurements definitively pin down where the Hugoniot intersects the melt curve - a source of some disagreement in recent years. Evidence is also presented for a change in the local structure of the liquid on shock release. The impact of these results are discussed. Finally, a sequence of solid-solid phase transformations is observed on shock compression as well as shock release and is detected by distinct changes in the obtained diffraction patterns. The well established sequence of solid-solid phase transformations observed in previous static studies is not observed in our experiments. Rather, Bi is found to exist in some metastable structures instead of forming equilibrium phases. The implications these results have for observing reconstructive phase transformations in other materials on shock timescales are discussed.
593

Corner effects for oblique shock wave/turbulent boundary layer interactions in rectangular channels

Xiang, Xue January 2018 (has links)
In a rectangular cross-section wind tunnel a separated oblique shock reflection is set to interact with the turbulent boundary layer (oblique SBLI) both on the bottom wall and in the corner formed by the intersection of the floor with the side-walls. In such a scenario, shock-induced separation is often seen in each of the streamwise corners, resulting in a highly three-dimensional flow field in the near-wall region. To examine how the corner separations can affect the `quasi-two-dimensional' main interaction and by what mechanism this is achieved, an experimental investigation has been conducted. This examines how modifications to the corner separation influence an oblique shock reflection. The nature of the flow field is studied using flow visualisation, Pressure Sensitive Paint and Laser Doppler Anemometry. A nominal freestream Mach number of 2.5 is used for all experiments with a unit Reynolds number of $40\times10^6$m$^{-1}$, and the shock-generator angle is set to $8^\circ$. The flow conditions are chosen to result in substantial separations both in the corners and along the centreline for the baseline case, which is thought to be a good starting point for this study. The results show that the size and shape of central separation vary considerably when the onset and magnitude of corner separation change. The primary mechanism coupling these separated regions appears to be the generation of compression waves and expansion fans as a result of the displacement effect of the corner separation. The presence and strength of the expansion waves have been overlooked in previous studies. This is shown to modify the three-dimensional shock-structure and alter the adverse pressure gradient experienced by the tunnel floor boundary layer. It is suggested that a typical oblique SBLI in rectangular channels features several zones depending on the relative position of the corner waves and the main interaction domain. In particular, it has been shown that the position of the corner `shock' crossing point, found by approximating the corner compression waves by a straight line, is a critical factor determining the main separation size and shape. Thus, corner effects can substantially modify the central separation. This can cause significant growth or contraction of the separation length measured along the symmetry line from the nominally two-dimensional baseline value, giving a fivefold increase from the smallest to the largest observed value. Moreover, the shape and flow topology of the centreline separation bubble is also considerably changed by varying corner effects.
594

Shock wave interaction with porous compressible foams

Atkins, Mark D January 2016 (has links)
Two foams, a polyether (density 32.5 kg/m3) and a polyester (density 38 kg/m3) foam were tested in a shock tube to analyze the interaction of a normal shock wave and a compressible porous material. The foam specimens were placed in the shock tube test section! the foam being bounded by two steel walis, two glass windows and a solid back plate. The compression chamber of the shock tube was pressurized and the diaphragm separating the compression chamber and the expansion chamber was ruptured, thus producing a normal shock wave which travels down the shock tube and strikes the foam. Piezoelectric pressure transducers 'vvera used to record the pressure before, alongside and behind the foam. A complete set of schlieren photographs, recording the interaction of the incident shock wave and the porous material were taken for each foam. A method ,tortracking the path of particles of foam (path photographs) was developed. Combining the information obtained from the pressure records, schlieren photographs and path photographs a complete picture of the shock wave foam interaction was developed. All the gas waves were identified and analyzed, A foam wave (velocity 90 m/s) travelling through the skeleton of the material was discovered. A physical model was developed to explain the high pressure recorded behind the foam. This model is based upon the foam being compressed and forming an almost solid piston, thus forcing the trapped gas into a diminishing volume and creating a high pressure behind the foam. The theoretical analyses of Monti (30), Gel'fand (20) and IBvozdeva (22) were analyz.ed and compared. The general finding was that for the range of incident mach numbers 1.~i1 to 1.46 Monti's analysis under predicts the reflected Mach number by 3 % and Gel'fand's analysis over predicts the reflected Mach number by 6 %. The coefficient of pressure increase (the ratio of the maximum pressure recorded behind the foam to the equivalent pressure recorded during ~he reflection of a shock wave from a solid wall) as predicted iJy Gvoz.deva's ane.lysisfor the polyether foam lies wjthin the scatter of the experimental results. However for the polyester foam Gvozdeva's analysis under predicts the coefficient of pressure increase by 15%. / GR 2016
595

Avaliação da atividade imunoterapêutica do probiótico LLHsp65 na asma experimental / Evaluation of the immunotherapeutic activity of probiotic LLHsp65 in asthma experimental

Lacerda, Luna Barrôco de 23 August 2017 (has links)
A asma alérgica é uma doença pulmonar de inflamação crônica caracterizada por uma resposta imune do tipo Th2 e uma das principais abordagens terapêuticas para o seu tratamento no futuro, poderia ser a imunoterapia baseada na modulação da resposta imune Th2 para um perfil Th1 e anti-inflamatório. Nosso grupo já demonstrou a eficácia de uma imunoterapia, baseada em um plasmídeo de DNA contendo o gene hsp65 de M. Leprae (DNAHsp65) em modelo murino de asma alérgica. No entanto, apesar dos excelentes resultados, o grupo está procurando outras alternativas imunoterapêuticas, usando a Hsp65 micobacteriana, para futura utilização clinica na área de saúde humana e veterinária. Efeitos benéficos na prevenção e tratamento de doenças alérgicas vêm sendo obtidos com o uso de probióticos. Nossa hipótese é de que uma nova formulação terapêutica, como o probiótico Lactococcus lactis expressando Hsp65 micobacteriana (LLHsp65), apresentaria vantagens significativas no desenvolvimento de pesquisas translacionais. Diante disso, este estudo teve como objetivo avaliar se o probiótico LLHsp65 apresenta atividades imunoterapêuticas no modelo de asma experimental induzida por ovalbumina (OVA). Em diferentes grupos experimentais, 5x109 CFU de LLHsp65 ou de L. lactis selvagem (LLSELV), foram administrados por via oral durante 10 dias consecutivos aos camundongos BALB/c previamente sensibilizados e desafiados com OVA. Em seguida, investigamos os efeitos do tratamento na inflamação alérgica, modulação do padrão de citocinas, produção de anticorpos específicos, hiper-responsividade das vias aéreas e inflamação pulmonar. Nossos resultados demonstraram que o tratamento oral com LLhsp65 modula a resposta imune alérgica de padrão Th2 para o perfil Th1 com aumento dos níveis de IFN-?, IL-12, TNF-?, IL-10, IL-6 e IL- 17, e com a redução das citocinas IL-4, IL-5 e IL-13. Os níveis de IgE e IgG1 anti-OVA no soro também foram significativamente diminuídos. Como consequência desses resultados, também observamos diminuição significativa do infiltrado de eosinófilos no lavado broncoalveolar, na hiper-responsividade nas vias aéreas e a atenuação da inflamação e produção de muco no tecido pulmonar, quando comparados com o grupo controle (OVA/SAL). Por conseguinte, nossos resultados demonstraram que a administração oral de LLHsp65 proporciona uma melhora significativa do processo inflamatório alérgico induzido por OVA, sendo portanto, uma estratégia terapêutica promissora para o desenvolvimento de pesquisa translacional no tratamento de asma alérgica. / Allergic asthma is a chronic inflammatory lung disease characterized by a Th2-type immune response and one of the main therapeutic approaches to its treatment in the future could be immunotherapy based on the modulation of the Th2 immune response to a Th1 and anti-inflammatory profile. Our group has already demonstrated the efficacy of an immunotherapy based on a DNA plasmid carrying the mycobacterial hsp65 gene (DNAHsp65) in murine model of allergic asthma. However, despite the excellent results, our group is looking for other immunotherapeutic alternatives, using mycobacterial Hsp65, for future clinical use in the area of human and veterinary health. Beneficial effects in the prevention and treatment of allergic diseases have been obtained with the use of probiotics. Our hypothesis is that a new therapeutic formulation, such as the probiotic Lactococcus lactis expressing mycobacterial Hsp65 (LLHsp65), would present significant advantages in the development of translational research. The objective of this study was to evaluate whether the probiotic LLHsp65 has immunotherapeutic activities in the ovalbumin-induced asthma model. In different experimental groups, 5x109 CFU of LLHsp65 or control L. lactis (ctLL) were administered orally for 10 consecutive days to BALB/c mice previously sensitized and challenged with OVA. We then investigated the effects of treatment on allergic inflammation, modulation of the cytokine pattern, production allergen-specific antibodies, airway hyperresponsiveness and pulmonary inflammation. Our results demonstrated that oral treatment with LLhsp65 modulates the allergic Th2 immune response to Th1 profile with increased levels of IFN-?, IL-12, TNF-?, IL-10, IL-6 and IL-17 and with the reduction of IL-4, IL-5 and IL-13 cytokines. Serum anti-OVA IgE and IgG1 levels were also significantly decreased. Correspondingly with these results, we also observed a significant decrease in eosinophil infiltrate in bronchoalveolar lavage, airway hyper responsiveness and attenuation of inflammation and mucus production in lung tissue when compared to the control group (OVA/SAL). Therefore, our results demonstrated that oral administration of LLHsp65 provides a significant improvement of the OVA-induced allergic inflammatory process and is therefore a promising therapeutic strategy for the development of translational research in the treatment of allergic asthma.
596

Effects of Preexposure to Shock on Autoshaping

Eldred, Nancy L. 01 May 1981 (has links)
The safety signal hypothesis suggests that during the absence of stimuli predicting impending shock, the organism is not fearful. The stimuli which predict the absence of shock are therefore called safety signals. The purpose of the present study was to investigate some critical properties of safety signals. Such stimuli in an avoidance or escape situation, according to the opponent process model, are expected to acquire hedonic value opposite to shock. This study examined differences in conditioning variables between safety signals predicting different intensities of shock, and between safety signals present in procedures using predicted shock, and procedures using unpredicted shock. Additionally, the effects of inescapable unpredicted shock with no safety signals present were examined. The general procedure involved exposing pigeons to aversive Pavlovian conditioning and subsequently autoshaping these birds to stimuli which had predicted safety in the aversive situation. Dependent measures included trials to acquisition of the autoshaped response and subsequent rate of keypecking. In the six experimental groups, pigeons were repeatedly and inescapably shocked at either 30 or 90 volts. Each individual 0.5 sec shock was (a) predicted by a specific stimulus or (b) not predicted. Additionally and explicitly unpaired with the shock, a safety signal was presented. For each voltage level, a control group was repeatedly shocked with no stimuli presented at any time. Control groups were included which (a) received no aversive conditioning, (b) were autoshaped to a stimulus which had previously predicted shock, (c) received the aversive conditioning, and (4) were exposed to various stimuli but received no aversive reinforcement. The principal finding was that preexposure to strong shock resulted in delays in response acquisition during subsequent autoshaping. This suggests that the learned helplessness hypothesis obtains with classically conditioned responding. Additionally, the importance of shock-alone control groups in the study of transfer effects is critical. Due to the lack of statistical power, the study was not definitive regarding the nature of safety signals or appetitive-to-appetitive transfers. Statistically significant differences were only found on acquisition measures, and no such differences were found on performance measures.
597

The Influence of Trichinella Spiralis Infection on Heat Shock Protein 72 Production in MRL++ Mouse Intestinal Cells

Kilejian, Lisa Ann 16 July 1993 (has links)
The production of Heat Shock Protein 72, the inducible for~ of the highly conserved 70 kilodalton heat shock protein family, was investigated in MRL++ mouse intestine during the two weeks of a Trichinella spiralis infection. Within hours of an oral infection using the encysted Trichinella spiralis found in the diaphragm of an infected mouse, the larvae are released from the cyst in the stomach. They travel to the intestine and burrow into the epithelial layer of the intestine. The jejunum is the primary site of the intestinal phase of trichinosis (Despommier 1983). This stage of infection in the jejunum was the focus of this study. Heat shock protein (HSP) synthesis is precipitated by stressful stimuli: in vitro by chemicals such as sodium arsenite and in vivo by cytoskeletal disturbance and/or toxic 02 radicals (Linquist 1986). The latter in vivo studies lend support to the inflammatory response induction of HSPs. Heat shock protein 72 (HSP72) is rarely expressed constitutively especially in non-primates and is a good indicator of various stresses. This study hypothesized that HSP72 would be induced by cells in the jejunum of the MRL++ mouse during a Trichinella spiralis infection due to the stress of the parasitic infection. Different techniques were employed to investigate this hypothesis. Immunohistochemistry and immunoblots facilitated this study. Although immunoblots did not demonstrate HSP72 induction, immunohistochemical analysis suggested the presence of HSP72 in various cells in the lamina propria of the jejunal villi.
598

Disseminating the Sepsis Bundle: Evaluating an Evidence-Based Education Module

Isopo, Elyse Diana 01 January 2018 (has links)
Due to increasing incidence and noncompliance with sepsis at a local hospital, an educational deficit was identified on the sepsis bundle in the medical intensive care unit. The purpose of this project was to develop and validate a sepsis bundle education program for all frontline staff in the MICU at a local University Hospital. The goal was for the educational tool to be validated by a multidisciplinary team to increase awareness, education, and ultimately, compliance with the severe sepsis and septic shock guidelines. The diffusion of innovation theory was utilized to support the process of change by encouraging the use of screening tools and best practice guidelines. The research question asked whether the education program meets critical care expert panel standards to educate frontline MICU staff on the sepsis bundle. The research design included a 5-member panel of experts in critical care, utilizing the Likert scale to review the proposed educational project on the sepsis bundle. Results are averaged from each reviewer. Results from the review included a unanimous '5' rating on every issue identified, equating to strongly agree on the Likert scale. This rating supported the validity of the educational project, the use of evidence-based practice and that the educational material was clear and easy to follow. Utilizing this validated tool will guide the education of sepsis, severe sepsis, and septic shock and promote social change by increasing education, awareness, recognition and early deployment of the sepsis bundle to improve patient outcomes.
599

Implementing a Sepsis Protocol in a Long-term Care Hospital

Harral, Kristine Lynette 01 January 2019 (has links)
Sepsis is life-threatening organ dysfunction caused by a response to infection that causes multiorgan failure. This condition causes high mortality and morbidity rates and leaves permanent disabilities. The purpose of this project was to create a sepsis protocol and an education training program for clinical staff in a hospital setting where no sepsis protocol was in place. The practice-focused question examined whether an educational program would improve clinical staff perception of their knowledge of the early recognition and management of sepsis. A literature review was conducted to identify an evidence-based practice protocol; the results were used to develop the education program for the clinical staff at the site. Malcolm Knowles'€™s theory of adult learning framed the project that included a team of 9 content experts consisting of physicians, physician assistants, and an educator who reviewed and approved the protocol and education program prior to implementation. The education program was then presented to 45 staff members including physicians, licensed vocational nurses, registered nurses, physician assistants, and nurse practitioners. Results of a 14-item knowledge test before and after the education program were examined for percent correct; results were compared using a paired-samples t test. Participant knowledge increased significantly (p <.05) from 20% correctly answering 10 of the 14 questions on the pretest to 87% answering all of the posttest questions correctly. The results of this project may promote positive social change by supporting clinical staff in early recognition and treatment of sepsis thereby reducing the morbidity and mortality that accompanies sepsis.
600

The synergistic effects of orthogonal biofilm mitigation strategies: thermal and antibiotic treatment

Ricker, Erica Noyes Bader 01 May 2017 (has links)
Upon forming a biofilm, bacteria undergo several changes that prevent them from being eradicated with antimicrobials alone. These biofilms manifest as persistent infections and biofouling in the medical and industrial world, respectively, constituting an ongoing medical crisis and creating a huge financial burden. Biofilms on implanted medical devices cause thousands of patients each year to undergo multiple surgeries to explant and replace the implant, driving billions of dollars in increased health care costs due to the lack of viable treatment options for in situ biofilm eradication. Heat has been used to reliably eliminate biofilms for many years, but the temperatures employed are infeasible for many applications, particularly in vivo medical treatment. Remotely activated localized heat can be applied through a superparamagnetic iron oxide nanoparticle polymer coating when paired with an alternating magnetic field. However, there is very little known about the temperatures required to kill the biofilms and the effects of the heat in conjunction with antibiotics. To better understand the required parameters to effectively kill off bacteria in biofilms a variety of heat treatments were investigated for a variety of Pseudomonas aeruginosa biofilms grown in different conditions. Additionally, these heat treatments were combined with antibiotics to better understand any combined effects of the two orthogonal treatment plans. It was found that heat is an effective method for killing the bacteria in biofilms. Temperatures ranging from body temperature, 37 °C, to 80 °C were used to heat shock the biofilms for 1 to 30 minutes. Higher temperatures for short exposure times yielded similar results to lower temperatures for longer exposure time. Biofilms grown in different conditions did vary in their susceptibility to the heat shocks; however, at the higher temperatures the differences became negligible. Therefore, the more effective treatments were the higher temperature heat shocks with shorter exposure times to maximize bacterial cell death and minimize the potential heat transfer to the surrounding tissue. Regrowth studies indicate a critical post-shock bacterial loading (~103 CFU/cm2) below which the biofilms were no longer viable, while films above that loading slowly regrew to their previous population density. Combined treatments with antibiotics had synergistic effects for all antibiotics across a window of heat shock conditions. Erythromycin in particular, which showed no effect on the biofilm alone, decreased biofilm population by six orders of magnitude at temperatures which had no effect in the absence of antibiotics. These studies will evolve the understanding of biofilms and how to efficiently eradicate them on implant surfaces. The introduction of such a novel coating in conjunction with antibiotics could obviate thousands of surgeries and save billions of dollars spent on explantation, recovery, and re-implantation.

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