Estudo do efeito da radiação gama sobre as propriedades de blendas baseadas em polipropileno isotatico

Orientador : Edison BittencourtDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia QuimicaResumo: Devido a elevada demanda de materiais poliméricos na obtenção de produtos médico-cirúrgicos e da tendência mundial em direção à esterilização pela radiação gama, o presente trabalho constou da análise do comportamento de diversas formulações desenvolvidas quando submetidas a este tipo de radiação. Estas análises foram realizadas imediatamente após a exposição à radiação e durante o envelhecimento, às condições ambientais. As formulações desenvolvidas foram compostas de PP-isso/Ppat, à razões variantes, e de um bloqueador de radicais denominado Irganox 1010, que é um antioxidante fenólico, à concentração de 0,05%. Para estudo da influência do bloqueador de radicais no amarelamento das formulações, foi utilizado um segundo bloqueador de radicais, denominado Tinuvin 622, que é uma amina estericamente impedida, à concentração de 0,1%. Formulações constituídas de PP-isso/PEBD, à razões variantes, e Tinuvin 622 foram desenvolvidas com a finalidade de se avaliar a influêcia do PEBD no comportamento do PP-isso irradiado já que os dois polímeros têm diferentes comportamentos quando irradiados. Para o monitoramento do efeito da radiação nas amostras foram realizados testes de tensão-deformação, análises dos espectros de infravermelho, análises térmicas e coloriméticas. Verificou-se através dos resultados obtidos, que reticulações e cisões de cadeia são eventos que ocorrem simultânea e competitivamente durante a exposição à radiação. Observou-se um comportamento sinergético entre polipropileno atático e os bloqueadores de radicais. A degradação oxidativa foi observada para as amostras irradiadas durante o envelhecimentoAbstract: Due to a large demand for adequate utilization of polymeric materials esterilized by gamma rays in medical applications, in this work we studied different formulations based on isotactic polypropylene (iPP) in order to analyse its behavior under radiation. The formulations were based on mixtures of isotactic polypropylene and atactic polypropylene (at-PP), and a radical scavenger (Irganox 1010) at concentration of 0,05 %. The influence of the radical scavenger in the yellowing index of different formulations was studied with a second scavenger (Tinuvin 622) at concentration of 0,1 %. Formulations containing isotactic polypropylene and low density polyethylene were developed with Tinuvin 622, to investigate the effect of radiation on their characteristics, since these two homopolymers have significantly different properties when irradiated at low doses. The effect of radiation on the materials were evaluated through stress-strain curves, infrared spectra, thermal analysis and colorimetric measurements. Simultaneous crosslinking and chain scission occurred Sinergism between at-PP and radical scavenger was observed. Oxidative degradation was observed on irradiated samples submitted to aging after exposureMestradoCiencia e Tecnologia de MateriaisMestre em Engenharia Químic

Transconjunctival and Subciliary Approach in the Treatment of Orbital Fractures: A Study on Oculoplastic Complication

The aim of the present study was to compare lower eyelid post-operative complications, such as ectropion, entropion, and scleral show of orbital floor fractures, associated to the subciliary vs transconjunctival approaches

Prevalence of p53 dysregulations in feline oral squamous cell carcinoma and non-neoplastic oral mucosa

Squamous cell carcinoma is the most common malignant oral tumor in cats. The late presentation is one of the factors contributing to the detrimental prognosis of this disease. The immunohistochemical expression of the p53 tumor suppressor protein has been reported in 24% to 65% of feline oral squamous cell carcinomas, but no study has systematically evaluated in this tumor the presence of p53 encoding gene (TP53) mutations. The aim of this retrospective study was to determine whether p53 immunohistochemistry accurately reflects the mutational status of the TP53 gene in feline oral squamous cell carcinoma. Additionally, the prevalence of p53 dysregulation in feline oral squamous cell carcinoma was compared with that of feline non-neoplastic oral mucosa, in order to investigate the relevance of these dysregulations in cancer development. The association between p53 dysregulations and exposure to environmental tobacco smoke and tumor characteristics was further assessed. Twenty-six incisional biopsies of oral squamous cell carcinomas and 10 cases each of lingual eosinophilic granuloma, chronic gingivostomatitis and normal oral mucosa were included in the study. Eighteen squamous cell carcinomas (69%) expressed p53 and 18 had mutations in exons 5\u20138 of TP53. The agreement between immunohistochemistry and mutation analysis was 77%. None of non-neoplastic oral mucosa samples had a positive immunohistochemical staining, while one case each of eosinophilic granuloma and chronic gingivostomatitis harbored TP53 mutations. Unlike previously hypothesized, p53 dysregulations were not associated with exposure to environmental tobacco smoke. These results suggest an important role of p53 in feline oral tumorigenesis. Additionally, the immunohistochemical detection of p53 expression appears to reflect the presence of TP53 mutations in the majority of cases. It remains to be determined if the screening for p53 dysregulations, alone or in association with other markers, can eventually contribute to the early detection of this devastating disease

Beyond Weight Loss: Added Benefits Could Guide the Choice of Anti-Obesity Medications

Purpose of ReviewTo highlight the added benefits of approved and upcoming, centrally-acting, anti-obesity drugs, focusing not only on the most common metabolic and cardiovascular effects but also on their less explored clinical benefits and drawbacks, in order to provide clinicians with a tool for more comprehensive, pharmacological management of obesity.Recent FindingsObesity is increasingly prevalent worldwide and has become a challenge for healthcare systems and societies. Reduced life expectancy and cardiometabolic complications are some of the consequences of this complex disease. Recent insights into the pathophysiology of obesity have led to the development of several promising pharmacologic targets, so that even more effective drugs are on the horizon. The perspective of having a wider range of treatments increases the chance to personalize therapy. This primarily has the potential to take advantage of the long-term use of anti-obesity medication for safe, effective and sustainable weight loss, and to concomitantly address obesity complications/comorbidities when already established.SummaryThe evolving scenario of the availability of anti-obesity drugs and the increasing knowledge of their added effects on obesity complications will allow clinicians to move into a new era of precision medicine

Control of polymorphism in thiophene derivatives by sublimation-aided nanostructuring

Here we applied the concept of "sublimation-aided nanostructuring" to control the polymorphism of a model material

Evaluation of Ki-67 expression in feline non-ocular melanocytic tumours

Fifty tumours located in skin (n = 33) and mucosae (n = 17) were included. Forty-eight percent and 95% of amelanotic tumours (n = 21) stained positive for Melan A and S100, respectively. Most achromic tumours were mucosal (P  5, Ki-67 > 20% and lack of treatment administration. On multivariable analysis, only tumour histotype and treatment retained prognostic significance. Conclusions Although the majority of feline NOMs behave aggressively, Ki-67 index, together with other parameters, may contribute to prognostic assessment. Prospective studies on homogeneous populations are warranted to identify reliable threshold values for this marker

Clinical Features and Outcome of 79 Dogs With Digital Squamous Cell Carcinoma Undergoing Treatment: A SIONCOV Observational Study

In dogs, digit squamous cell carcinoma (SCC) is uncommon. Clinical signs are frequently underestimated, leading to a diagnostic delay. The purpose of this retrospective study was to report our experience regarding the clinical presentation, diagnostic work-up, treatment and outcome of 79 client-owned dogs with SCC of the digit. The greatest majority (84.8%) of dogs was dark-coated. Schnauzers represented approximately one third of the study population, and had a poorer outcome compared with other breeds. The majority of SCCs occurred in the front limbs (61%), and bone lysis was frequently observed (92.4%). Approximately 9% of dogs had involvement of multiple digits, and this was associated with a shorter time to progression (TTP; P = 0.047). Similarly, a duration of clinical signs >90 days was associated with a shorter TTP (P = 0.02). Regional lymph node metastases were documented in 17.7% of dogs at admission and were significantly associated with tumor-related death (P < 0.001). At presentation, none of the dogs had evidence of distant metastasis. Digit amputation achieved adequate local tumor control in the majority of cases. Adjuvant chemotherapy and radiation therapy were carried out in 21.5% of cases, with uncertain benefit. Due to the relatively non-aggressive clinical behavior of digit SCC, chemotherapy should only be offered in the case of metastatic disease. Approximately one fourth of dogs developed de novo SCCs during the follow-up. Careful examination of the digits should be encouraged in breeds considered at high risk and in dogs with a previous history of digital SCC