Magnesium (Mg) and its alloys provide numerous unique benefits as potential resorptive biomaterials and present the very real possibility of replacing current metallic implant materials in a variety of roles. However, considerable research remains before Mg alloys may be accurately screened and used in vivo. Most critically, a more comprehensive understanding of the corrosion of Mg alloys in vitro is needed. This research program critically examined the types of in vitro experiments that may be performed on Mg alloys, investigated the numerous variables that affect Mg biodegradation when undertaking these experiments, explored the electrochemical performance of several biocompatible Mg alloys, and developed a novel process for producing ordered Mg structures. The benefits and drawbacks of a range of in vitro tests were first investigated. The key strengths and weaknesses of each test were identified and recommendations provided for their respective use in the quest to determine Mg alloy biodegradation. The most common variables applicable to all in vitro experiments were then explored in detail, and their effect on the biocorrosion of a number of Mg alloys was determined. Recommendations were then made for the appropriate control of the different experimental variables based on these findings. For the first time, the mechanistic control of Mg biodegradation by the microstructure of biocompatible alloys has been examined. This allows for greater understanding of the reasons for varied corrosion of alloys in bio-electrolytes, and is a step towards the effective design of Mg alloys for different bio-applications. A novel method to produce ordered Mg structures was developed, with relevant processing parameters investigated in light of their effect on biocorrosion and mechanical performance. Overall, the results and findings from this research further our understanding of the potential of Mg alloys as suitable biomaterials, and advance our knowledge of how to proceed towards the goal of using such alloys for biological applications.

A hipermatilação aberrante de regiões gênicas promotoras foi recentemente sugerida como meio de detecção do carcinoma epidermóide de cabeça e pescoço. Neste estudo nós avaliamos o status de metilação de um painel de 7 genes já relatados na literatura e sua correlação com lesões orais malignas e cancerizáveis de boca. Inicialmente, nós utilizamos amostras de enxágues salivares de pacientes com lesões benignas, displásicas e malignas para determinar a hipermetilação em regiões gênicas promotoras em pacientes de alto risco. Uma avaliação clínica de risco foi realizada e correlacionada com o diagnóstico histológico e status dos biomarcadores. A partir dos resultados analisados nas lesões intraorais, o gene DCC, que obteve a melhor performance entre os 7 genes, foi testado em lesões de queilite actínica e carcinoma epidermoide de lábio. Foram realizadas reações de PCR específica para metilação, quantitativa (Q-MSP) para os 7 genes (CCNA1, MGMT, MINT31, TIMP3, P16, DAPK, DCC) em enxágues salivares de 191 pacientes com lesões intraorais, e do gene DCC em 39 lesões de lábio. Análises de regressão logística e curva ROC foram utilizadas para avaliar a associação do status de metilação com o diagnóstico histológico e para estimar a acurácia da classificação respectivamente, nas amostras de enxágue salivar. Na análise multivariada, o diagnóstico displasia/ câncer foi associado com a idade (OR=1.3, 95% CI= (1.01-1.6, p=0.014) e a metilação do painel de 7 genes (OR=2.2, 95% CI=(1.34.0), p=0.006); a metilação do DCC também foi fortemente associada (OR=3.3, 95% CI=(1.7-6.6), p=0.004). Na análise multivariada, o diagnóstico histológico foi independentemente associado com a metilação do painel de 7 genes (OR=2.0, 95% CI=(1.1-3.6), p=0.027) ou do DCC (OR=2.8, 95% CI=(1.4-5.7), p=0.004). Uma nova análise, excluindo pacientes com diagnóstico prévio de câncer (n=30), e levando em conta uma classificação clínica de risco, foi realizada. Na análise univariada, DCC (OR=2.6, 95% CI=(1.1-6.1), p=0.026) e a classificação clínica de risco (OR=2.5, 95% CI=(1.3-5.1), p=0.008) foram associados com o diagnóstico de displasia/ câncer, e permaneceram significante na análise multivariada (DCC: OR=2.5, 95% CI= (1.1- 6.0), p=0.037, classificação de risco: OR=2.5, 95% CI=(1.2-5.0), p=0.012). A classificação clínica de risco identificou displasia/ câncer com a sensibilidade de (95% CI=4171%) e especificidade de 66% (95% CI= 5775%). A sensibilidade da classificação clínica de risco combinada com a metilação do painel de 7 genes melhorou, chegando a 71% (95% CI=5683%) e com a metilação do DCC chegou a 69% (95% CI=5481%). O status de metilação do painel de 7 genes, como também o DCC como um marcador individual, foi independentemente associado com o diagnóstico histológico em enxágues salivares. Nas lesões labiais não foi possível observar a mesma correlação entre o status de metilação do gene DCC e o diagnóstico histológico, provavelmente, devido a diferente etiologia das lesões intraorais e labiais. Os resultados mostram a potencial habilidade destes biomarcadores em prever o risco de presença de lesões intraorais cancerizáveis, usando uma abordagem não invasiva, além do potencial de melhorar a eficiência da classificação clínica de risco. Mas reforça a diferente etiologia das lesões intraorais e labiais e a necessidade de diferentes marcadores para essas lesões. / Aberrant promoter hypermethylation has been recently proposed as a means for detection of HNSCC in salivary rinses. Here we evaluate the ability of a previously reported 7-gene methylation panel status to correlate with premalignant and malignant oral lesions. We used a large prospective cohort of salivary rinses obtained from patients with benign, dysplastic, and cancer diagnoses to determine promoter hypermethylation in high-risk patients. Clinical risk assessment was performed and correlated with histological diagnosis and biomarker status. Also, a cohort of lip lesions was selected and methylation status of DCC gene was correlated with histology. Quantitative methylation-specific PCR (Q-MSP) was performed analyzing methylation status of 7 genes (CCNA1, MGMT, MINT31, TIMP3, P16, DAPK, DCC) in salivary rinses of 191 patients with oral lesion and 39 lip lesions. Logistic regression and receiver operating characteristic (ROC) analyses were used to examine the association of methylation status with histologic diagnosis and to estimate classification accuracy, respectively. On univariate analysis, diagnosis of dysplasia/cancer was associated with age (OR=1.3, 95% CI= (1.01-1.6, p=0.014) and 7-gene panel methylation (OR=2.2, 95% CI=(1.34.0), p=0.006); DCC methylation was also strongly associated (OR=3.3, 95% CI=(1.7-6.6), p=0.004). On multivariable modeling, histologic diagnosis was independently associated with 7 gene panel (OR=2.0, 95% CI=(1.1-3.6), p=0.027) or DCC (OR=2.8, 95% CI=(1.4- 5.7), p=0.004) methylation. A subset analyzed (n=161) without prior biopsy proven malignancy received clinical risk classification based on lesion examination. On univariate analysis, DCC (OR=2.6, 95% CI=(1.1-6.1), p=0.026) and clinical risk classification (OR=2.5, 95% CI=(1.3-5.1), p=0.008) were associated with diagnosis of dysplasia/cancer, and remained significant on multivariate analysis (DCC: OR=2.5, 95% CI= (1.1-6.0), p=0.037, risk classification: OR=2.5, 95% CI=(1.2-5.0), p=0.012). Clinical risk classification identified dysplasia/cancer with a sensitivity of 56% (95% CI=4171%) and specificity of 66% (95% CI= 5775%). The sensitivity of clinical risk classification combined with 7-gene panel methylation improved to 71% (95% CI=56 83%) and with DCC methylation improved to 69% (95% CI=5481%). The 7-gene panel methylation, as well DCC as a single marker, was independently associated with histologic diagnosis in salivary rinses. No correlation was found between DCC methylation status and histologic diagnosis of lip lesions, probably due different etiology of oral and lip lesions. The results show the potential ability of these biomarkers to predict risk for presence of oral premalignancy and malignancy using a non-invasive approach using salivary rinse and can improve the efficiency of clinical risk classification. Also, reinforces the different etiologic origins of intraoral and lip lesions and the need of different markers for these lesions.

A hipermatilação aberrante de regiões gênicas promotoras foi recentemente sugerida como meio de detecção do carcinoma epidermóide de cabeça e pescoço. Neste estudo nós avaliamos o status de metilação de um painel de 7 genes já relatados na literatura e sua correlação com lesões orais malignas e cancerizáveis de boca. Inicialmente, nós utilizamos amostras de enxágues salivares de pacientes com lesões benignas, displásicas e malignas para determinar a hipermetilação em regiões gênicas promotoras em pacientes de alto risco. Uma avaliação clínica de risco foi realizada e correlacionada com o diagnóstico histológico e status dos biomarcadores. A partir dos resultados analisados nas lesões intraorais, o gene DCC, que obteve a melhor performance entre os 7 genes, foi testado em lesões de queilite actínica e carcinoma epidermoide de lábio. Foram realizadas reações de PCR específica para metilação, quantitativa (Q-MSP) para os 7 genes (CCNA1, MGMT, MINT31, TIMP3, P16, DAPK, DCC) em enxágues salivares de 191 pacientes com lesões intraorais, e do gene DCC em 39 lesões de lábio. Análises de regressão logística e curva ROC foram utilizadas para avaliar a associação do status de metilação com o diagnóstico histológico e para estimar a acurácia da classificação respectivamente, nas amostras de enxágue salivar. Na análise multivariada, o diagnóstico displasia/ câncer foi associado com a idade (OR=1.3, 95% CI= (1.01-1.6, p=0.014) e a metilação do painel de 7 genes (OR=2.2, 95% CI=(1.34.0), p=0.006); a metilação do DCC também foi fortemente associada (OR=3.3, 95% CI=(1.7-6.6), p=0.004). Na análise multivariada, o diagnóstico histológico foi independentemente associado com a metilação do painel de 7 genes (OR=2.0, 95% CI=(1.1-3.6), p=0.027) ou do DCC (OR=2.8, 95% CI=(1.4-5.7), p=0.004). Uma nova análise, excluindo pacientes com diagnóstico prévio de câncer (n=30), e levando em conta uma classificação clínica de risco, foi realizada. Na análise univariada, DCC (OR=2.6, 95% CI=(1.1-6.1), p=0.026) e a classificação clínica de risco (OR=2.5, 95% CI=(1.3-5.1), p=0.008) foram associados com o diagnóstico de displasia/ câncer, e permaneceram significante na análise multivariada (DCC: OR=2.5, 95% CI= (1.1- 6.0), p=0.037, classificação de risco: OR=2.5, 95% CI=(1.2-5.0), p=0.012). A classificação clínica de risco identificou displasia/ câncer com a sensibilidade de (95% CI=4171%) e especificidade de 66% (95% CI= 5775%). A sensibilidade da classificação clínica de risco combinada com a metilação do painel de 7 genes melhorou, chegando a 71% (95% CI=5683%) e com a metilação do DCC chegou a 69% (95% CI=5481%). O status de metilação do painel de 7 genes, como também o DCC como um marcador individual, foi independentemente associado com o diagnóstico histológico em enxágues salivares. Nas lesões labiais não foi possível observar a mesma correlação entre o status de metilação do gene DCC e o diagnóstico histológico, provavelmente, devido a diferente etiologia das lesões intraorais e labiais. Os resultados mostram a potencial habilidade destes biomarcadores em prever o risco de presença de lesões intraorais cancerizáveis, usando uma abordagem não invasiva, além do potencial de melhorar a eficiência da classificação clínica de risco. Mas reforça a diferente etiologia das lesões intraorais e labiais e a necessidade de diferentes marcadores para essas lesões. / Aberrant promoter hypermethylation has been recently proposed as a means for detection of HNSCC in salivary rinses. Here we evaluate the ability of a previously reported 7-gene methylation panel status to correlate with premalignant and malignant oral lesions. We used a large prospective cohort of salivary rinses obtained from patients with benign, dysplastic, and cancer diagnoses to determine promoter hypermethylation in high-risk patients. Clinical risk assessment was performed and correlated with histological diagnosis and biomarker status. Also, a cohort of lip lesions was selected and methylation status of DCC gene was correlated with histology. Quantitative methylation-specific PCR (Q-MSP) was performed analyzing methylation status of 7 genes (CCNA1, MGMT, MINT31, TIMP3, P16, DAPK, DCC) in salivary rinses of 191 patients with oral lesion and 39 lip lesions. Logistic regression and receiver operating characteristic (ROC) analyses were used to examine the association of methylation status with histologic diagnosis and to estimate classification accuracy, respectively. On univariate analysis, diagnosis of dysplasia/cancer was associated with age (OR=1.3, 95% CI= (1.01-1.6, p=0.014) and 7-gene panel methylation (OR=2.2, 95% CI=(1.34.0), p=0.006); DCC methylation was also strongly associated (OR=3.3, 95% CI=(1.7-6.6), p=0.004). On multivariable modeling, histologic diagnosis was independently associated with 7 gene panel (OR=2.0, 95% CI=(1.1-3.6), p=0.027) or DCC (OR=2.8, 95% CI=(1.4- 5.7), p=0.004) methylation. A subset analyzed (n=161) without prior biopsy proven malignancy received clinical risk classification based on lesion examination. On univariate analysis, DCC (OR=2.6, 95% CI=(1.1-6.1), p=0.026) and clinical risk classification (OR=2.5, 95% CI=(1.3-5.1), p=0.008) were associated with diagnosis of dysplasia/cancer, and remained significant on multivariate analysis (DCC: OR=2.5, 95% CI= (1.1-6.0), p=0.037, risk classification: OR=2.5, 95% CI=(1.2-5.0), p=0.012). Clinical risk classification identified dysplasia/cancer with a sensitivity of 56% (95% CI=4171%) and specificity of 66% (95% CI= 5775%). The sensitivity of clinical risk classification combined with 7-gene panel methylation improved to 71% (95% CI=56 83%) and with DCC methylation improved to 69% (95% CI=5481%). The 7-gene panel methylation, as well DCC as a single marker, was independently associated with histologic diagnosis in salivary rinses. No correlation was found between DCC methylation status and histologic diagnosis of lip lesions, probably due different etiology of oral and lip lesions. The results show the potential ability of these biomarkers to predict risk for presence of oral premalignancy and malignancy using a non-invasive approach using salivary rinse and can improve the efficiency of clinical risk classification. Also, reinforces the different etiologic origins of intraoral and lip lesions and the need of different markers for these lesions.

No description available.

In modular hip implants, micro-motion, which leads to fretting corrosion at the head/neck and neck/stem interfaces, has been identified as a major cause of early revision in hip implants, particularly those with heads larger than 32mm. It has been found that the type of fluid used to simulate the fretting corrosion of biomedical materials is crucial for the reliability of laboratory tests. Therefore, to properly understand and effectively design against fretting corrosion damage in modular hips, there is the need to replicate the human body environment as closely as possible during in-vitro testing and validation. In this work, corrosion behavior of CoCrMo in 0.14 M NaCl, phosphate buffered saline (PBS) and clinically relevant simulated body fluid (sbf) is carried out. Also, fretting corrosion studies of the CoCrMo alloy in a clinically relevant novel simulated body fluid (sbf) environment is studied. The presence of phosphate ions in PBS accounted for the higher corrosion rate when compared with 0.14 M NaCl and sbf environment. Despite the low and comparable corrosion rates in 0.14 M NaCl and sbf, the nature of the protective passive film formed in sbf shows the suitability of the novel sbf for future corrosion and fretting corrosion analysis. Finally, the influence of micro-motion at the modular head/neck and neck/stem interfaces on the concentration of metallic ions that goes into the synovial fluid and surrounding tissues is reported.

Made available in DSpace on 2014-06-12T15:50:51Z (GMT). No. of bitstreams: 2 arquivo5257_1.pdf: 9930279 bytes, checksum: 23011bff0745721e6391ddb8c270a9dc (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2006 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Compósitos feitos a partir do polímero policaprolactona e de carbonato de cálcio, chamados de PCLC, foram preparados por um processo de carbonatação, que consiste em incidir um fluxo constante de gás carbônico (CO2) em uma solução de metanol e hidróxido de cálcio por 6 horas e depois adicionar ao polímero diluído em diclorometano, após a secagem e evaporação dos solventes o material resultante é prensado no formato de pastilhas. Essas pastilhas foram então expostas, a uma solução simuladora de fluido corporal (SBF) sob temperatura constante de 37 0C, por períodos de 3, 6, 12 e 24 horas e por 7, 14, 21 e 28 dias, o que levou à deposição de estruturas do tipo apatita, semelhantes aos ossos humanos sobre sua superfície. Antes e após ser exposto ao SBF, o compósito PCLC foi analisado por diferentes técnicas de caracterização de materiais, tais como difratometria de raios-X, espectroscopia de infravermelho com transformada de Fourier (FTIR), calorimetria diferencial de varredura (DSC), microscopia eletrônica de varredura (MEV) e espectroscopia dispersiva de raios-X (EDX). Através dessa análise foi possível detectar a formação de apatitas na superfície do PCLC já a partir de 3 horas de exposição ao SBF, sendo a deposição de material inorgânico crescente com o tempo, ocorrendo variação de fases minerais e o aparecimento de hidroxiapatita após 21 dias, o que sugere a indicação do compósito PCLC como um promissor material para o desenvolvimento de implantes biocompatíveis a serem utilizados no corpo humano

This work deals with bioceramic materials based of hydroxyapatite, bioglass and their composites. These materials are commonly used in medicine, especially as hard tissue substituents. They can be prepared by different types of syntheses, from which the most common were picked for this work – precipitation of hydroxyapatite and sol-gel method for bioglass. Thermal analysis and X-ray diffraction were used for characterization of prepared powders. This thesis studies mostly their features within the composite materials, which were foamed for better bone stimulation. Properties and possibility in bio application of materials is firstly studied through their interaction in simulated body fluids, which mimics ionic concentration of human plasma. Experimental part covers synthesis of ceramic powders, their characterization, preparation of mixtures and scaffolds foamed through in situ foaming, their sintering at ideal temperatures, characterization of porosity and phase changes due to sintering. Basic tests of apatite formation ability were provided by incubation of prepared scaffolds in simulated body fluid for 3, 7, 14 and 21 days and their assay in scanning electron microscopy. Changes in concentration of Ca2+ a PO4 3- ions as well as in weight of the specimen were tracked within the incubation period.

Studies regarding the feasibility of ovalbumin (OVA) as a bone scaffold material have found its cost, availability, interaction with cells, and ability to degrade in the body into safe byproducts to be ideal for such an application. However, weak mechanical properties cause hesitation in the use of OVA as a scaffolding material in much stronger native tissue. To enhance the mechanical strength of the OVA scaffolds without compromising in vitro cellular performance, Ca-P crystals were grown on unmodified OVA and phosphonated OVA (p-OVA) samples via biomineralization processes using 5x-concentrated simulated body fluid (5x SBF). Electron microscopy (ESEM/EDS) data confirm the formation of Ca-P crystals on the surface of OVA and p-OVA scaffolds. Mechanically, rheology data measured a minimum of a three-fold increase in each mineralized scaffold's complex shear modulus over unmineralized counterparts. Degradation in a PBS+collagenase XI environment showed that mineralization extended total time to degradation. It was also shown that the formation of the Ca-P crystals had no negative effects on in vitro cell studies. To measure cellular response, a live/dead assay was conducted to confirm cell viability after 24 hours. In conclusion, improvements were made to mechanical strength without compromising in vitro cell-scaffold response. While it remains unknown whether the increase in strength is adequate for use as a bone scaffold, future work should focus on gathering necessary information to study OVA scaffolds in animal models for eventual consideration as a bone graft substitute material. / Master of Science

Vaginal fluid is most often found at crime scenes where a sexual assault has taken place or on clothing or other items collected from sexual assault victims or perpetrators. Because the victim is generally known in these cases, detection of vaginal fluid is not a matter of individual identification, as it might be for semen identification. Instead, linkages can be made between victim and suspect if the sexual assault was carried out digitally or with a foreign object (e.g., bottle, pool cue, cigarette, handle of a hammer or other tool, etc.). If such an object is only analyzed for DNA and the victim is identified, the suspect may claim that the victim’s DNA is present because she handled and/or is the owner of the object and not because it was used to sexually assault her; identification of vaginal fluid residue would alleviate such uncertainty. Most of the research conducted thus far regarding methods for the identification of vaginal fluid involves mRNA biomarkers and identification of various bacterial strains.1-3 However, these approaches require extensive sample preparation and laboratory analysis and have not fully explored the genomic differences among all body fluid RNAs. No existing methods of vaginal fluid identification incorporate both high specificity and rapid analysis.4 Therefore, a new rapid detection method is required. Surface-enhanced Raman spectroscopy (SERS) is an emerging technique with high sensitivity for the forensic analysis of various body fluids. This technique has the potential to improve current vaginal fluid identification techniques due to its ease-of-use, rapid analysis time, portability, and non-destructive nature. For this experiment, all vaginal fluid samples were collected from anonymous donors by saturation of a cotton swab via vaginal insertion. Samples were analyzed on gold nanoparticle chips.4 This nanostructured metal substrate is essential for the large signal-enhancement effect of SERS and also quenches any background fluorescence that sometimes interferes with normal Raman spectroscopy measurements.5 Vaginal fluid SERS signal variation of a single sample over a six-month period was evaluated under both ambient and frozen storage conditions. Vaginal fluid samples were also taken from 10 individuals over the course of a single menstrual cycle. Four samples collected at one-week intervals were obtained from each individual and analyzed using SERS. The SERS vaginal fluid signals showed very little variation as a function of time and storage conditions, indicating that the spectral pattern of vaginal fluid is not likely to change over time. The samples analyzed over the span of one menstrual cycle showed slight intra-donor differences, however, the overall spectral patterns remained consistent and reproducible. When cycle spectra were compared between individuals, very little donor-to-donor variation was observed indicating the potential for a universal vaginal fluid signature spectrum. A cross-validated, partial least squares – discriminant analysis (PLS-DA) model was built to classify all body fluids, where vaginal fluid was identified with 95.0% sensitivity and 96.6% specificity, which indicates that the spectral pattern of vaginal fluid was successfully distinguished from semen and blood. Thus, SERS has a high potential for application in the field of forensic science for vaginal fluid analysis.

Akademisk avhandling--Karolinska institutet, Stockholm. / Added t.p. with thesis statement inserted. Includes bibliographical references.