Structural investigation of the Bacillus subtilis morphogenic factor RodZ

A thesis to obtain a Master degree in Structural and Functional Biochemistry

A relevância do factor de transcrição Yap5 de Saccharomyces cerevisiae na resposta ao excesso de ferro

A capacidade que os organismos possuem de alterar os seus padrões de expressão de genes em resposta a alterações no meio ambiente é essencial para a sua viabilidade. A levedura Saccharomyces cerevisiae, em particular, possui um programa complexo e muito flexível de expressão de genes quando exposta a mudanças agressivas do seu meio ambiente. As células mantêm a sua homeostase através de mecanismos coordenados de regulação de vários factores de transcrição, cada um desempenhando funções específicas. Neste trabalho foi estudada a relevância do factor de transcrição da família Yap de S. cerevisiae, o Yap5, na destoxificação do excesso de ferro na célula. Os resultados obtidos neste trabalho mostram que após a incubação com elevadas quantidades de sulfato de ferro, embora o potencial de transactivação do Yap5 aumente, os níveis da proteína diminuem, sendo esta diminuição dependente da concentração de ferro. Demonstrámos também que embora a expressão do gene CCC1 (que codifica para o único transportador vacuolar de ferro conhecido) seja dependente do Yap5 em condições de excesso de ferro, os níveis basais de expressão deste gene são suficientes para a sobrevivência nessas condições. Observámos ainda que, ao contrário do que acontece em Schizosaccharomyces pombe, o factor de transcrição Hap4, não parece estar envolvido nesta regulação. Através de delecções sequenciais da região promotora do CCC1, verificámos que os níveis de expressão ditados por uma região de 58pb a montante do codão de iniciação, ATG, são suficientes para a célula sobreviver sob concentrações elevadas de ferro. Verificámos ainda que a região 3’UTR do gene é importante para a sobrevivência celular. Nessa região, identificámos uma estrutura em forma de “hairpin” que poderá estar envolvida na regulação do gene.

Novel functions of the cohesin accessory factor dPDS5 uncover a new meiotic checkpoint

Dissertation presented to obtain the Ph.D degree in Biology.

Optimização do factor de cobertura de condensadores de tântalo produzidos com pós de elevada carga específica

Dissertação para obtenção do Grau de Doutor em Nanotecnologias e Nanociências

Reinfections with strains of Trypanosoma cruzi, of different biodemes as a factor of aggravation of myocarditis and myositis in mice

Reinfections with Trypanosoma cruzi in patients from endemic areas have been claimed to be an aggravation factor of cardiac manifestations in Chagas' disease. In the present study, the influence of triple infections with strains of different biodemes, on cardiac and skeletal muscle lesions was experimentally tested. Fifty eight mice chronically infected with the Colombian strain (Biodeme Type III) were successively reinfected as follows: 1st group - reinfected with 21 SF strain (Type II) followed by Y strain (Type I ); 2nd - group reinfections with Y strain followed by 21SF strain. Isoenzyme analysis of parasites from hemocultures obtained from triple infected mice, revealed the patterns of three distinct zymodemes in the same animal. Each Trypanosoma cruzi strain was reisolated after four passages in mice on either the 7th, 14th or 30th day after inoculation with the blood of triple infected mice. Histopathology results demonstrated a significant exacerbation of cardiac and skeletal muscle inflammatory lesions, confirmed by morphometric evaluation, in mice with triple infection. No aggravation of parasitism was detected. The possibility of an enhancement of cellular response in the triple infected mice is suggested.

Serum levels of interleukin-6, tumor necrosis factor-alpha and interferon-gama in infants with and without dengue

This study compared the serum levels of IL-6, TNF-alpha and IFN-gamma, in children under 1 year of age with and without dengue. Sera were collected from a total of 41 children living in the Department of Antioquia, Colombia (27 patients with dengue and 14 controls). The results showed higher cytokine levels in children with dengue than without dengue, with statistically significant differences for IL-6 and IFN-gamma. No statistically significant differences were found between clinical forms, although IL-6 and IFN-gamma levels were higher in dengue fever cases than in dengue hemorrhagic fever cases. On the other hand, TNF-alpha levels were higher in dengue hemorrhagic fever than in dengue fever. The levels of IL-6 and TNF-alpha were higher in secondary infection than in primary infection, although IFN-gamma levels were higher in primary infection. These results suggest that IL-6, TNF-alpha and IFN-gamma are involved in dengue infection independently of the clinical form.

HAART: a risk factor for development of porphyria cutanea tarda?

Porphyria cutanea tarda (PCT) is caused by inherited or acquired partial deficiency of the uroporphyrinogen-decarboxylase (Uro-D) enzyme activity. It is the most common form of porphyria. The main triggering factors to the development of porphyria cutanea tarda are alcohol, hepatitis C virus and human immunodeficiency virus. There are several reports of PCT associated with drugs, among them, antiretroviral therapy. We describe three HIV-positive patients, which showed photosensitivity as well as the emergence of tense blisters on sun-exposed areas during the use of highly active antiretroviral therapy (HAART) and discuss the possibility of PCT after the use of these drugs by those patients.

Glucocorticoid-induced tumor necrosis factor receptor expression in patients with cervical human papillomavirus infection

Introduction The progression of human papillomavirus (HPV) infection in the anogenital tract has been associated with the involvement of cells with regulatory properties. Evidence has shown that glucocorticoid-induced tumor necrosis factor receptor (GITR) is an important surface molecule for the characterization of these cells and proposes that GITR ligand may constitute a rational treatment for many cancer types. We aimed to detect the presence of GITR and CD25 in cervical stroma cells with and without pathological changes or HPV infection to better understand the immune response in the infected tissue microenvironment. Methods We subjected 49 paraffin-embedded cervical tissue samples to HPV DNA detection and histopathological analysis, and subsequently immunohistochemistry to detect GITR and CD25 in lymphocytes. Results We observed that 76.9% of all samples with high GITR expression were HPV-positive regardless of histopathological findings. High GITR expression (77.8%) was predominant in samples with ≥1,000 RLU/PCB. Of the HPV-positive samples negative for intraepithelial lesion and malignancy, 62.5% had high GITR expression. High GITR expression was observed in both carcinoma and high-grade squamous intraepithelial lesion (HSIL) samples (p = 0.16). CD25 was present in great quantities in all samples. Conclusions The predominance of high GITR expression in samples with high viral load that were classified as HSIL and carcinoma suggests that GITR+ cells can exhibit regulatory properties and may contribute to the progression of HPV-induced cervical neoplasia, emphasizing the importance of GITR as a potential target for immune therapy of cervical cancer and as a disease evolution biomarker.

Urinary tract infection in full-term newborn infants: risk factor analysis

OBJECTIVE: To analyze the correlation of risk factors to the occurrence of urinary tract infection in full-term newborn infants. PATIENTS AND METHODS: Retrospective study (1997) including full-term infants having a positive urine culture by bag specimen. Urine collection was based on: fever, weight loss > 10% of birth weight, nonspecific symptoms (feeding intolerance, failure to thrive, hypoactivity, debilitate suction, irritability), or renal and urinary tract malformations. In these cases, another urine culture by suprapubic bladder aspiration was collected to confirm the diagnosis. To compare and validate the risk factors in each group, the selected cases were divided into two groups: Group I - positive urine culture by bag specimen collection and negative urine culture by suprapubic aspiration, and Group II - positive urine culture by bag specimen collection and positive urine culture by suprapubic aspiration . RESULTS: Sixty one infants were studied, Group I, n = 42 (68.9%) and Group II, n = 19 (31.1%). The selected risk factors (associated infectious diseases, use of broad-spectrum antibiotics, renal and urinary tract malformations, mechanical ventilation, parenteral nutrition and intravascular catheter) were more frequent in Group II (p<0.05). Through relative risk analysis, risk factors were, in decreasing importance: parenteral nutrition, intravascular catheter, associated infectious diseases, use of broad-spectrum antibiotics, mechanical ventilation, and renal and urinary tract malformations. CONCLUSION: The results showed that parenteral nutrition, intravascular catheter, and associated infectious diseases contributed to increase the frequency of neonatal urinary tract infection, and in the presence of more than one risk factor, the occurrence of urinary tract infection rose up to 11 times.

Immunoglobulin E-rheumatoid factor in juvenile rheumatoid arthritis

OBJECTIVES: To determine the presence of immunoglobulin E-rheumatoid factor in patients with juvenile rheumatoid arthritis and to correlate it with clinical and laboratory parameters. METHODS: A multicenter prospective study was carried out from January 1993 to January 1999 with the enrollment of 3 centers of pediatric rheumatology. Ninety-one children with juvenile rheumatoid arthritis diagnosed according to the American College of Rheumatology criteria were studied: 38 (42%) with systemic, 28 (31%) with pauciarticular, and 25 (27%) with polyarticular onset. Ages ranged from 2.1 years to 22.6 years (mean 10.5 ± 4.7), with 59 (65%) girls. The control group consisted of 45 healthy children. The detection of immunoglobulin E-rheumatoid factor was carried out utilizing an enzyme-linked immunosorbent assay. Associations of immunoglobulin E-rheumatoid factor with immunoglobulin M-rheumatoid factor (latex agglutination test), total serum immunoglobulin E, erythrocyte sedimentation rate, antinuclear antibody, and functional and radiological classes III or IV were analyzed. RESULTS: Positive immunoglobulin E-rheumatoid factor was found in 15 (16.5%) of the 91 children with juvenile rheumatoid arthritis: 7 (18.5%) with systemic, 5 (18%) with pauciarticular, and 3 (12%) with polyarticular onset. A significant correlation was observed between immunoglobulin E-rheumatoid factor and total serum immunoglobulin E in the juvenile rheumatoid arthritis patients. No correlation was found between immunoglobulin E-rheumatoid factor and positive latex agglutination slide test, erythrocyte sedimentation rate, antinuclear antibody, or the functional and radiological classes III or IV in any disease onset group. In 4 out of 45 control children (8.9%), immunoglobulin E-rheumatoid factor was positive but with no correlation with total serum immunoglobulin E levels. CONCLUSIONS: Immunoglobulin E-rheumatoid factor could be detected in 16.5% of juvenile rheumatoid arthritis patients, particularly in those with high levels of total serum immunoglobulin E, and immunoglobulin E-rheumatoid factor appears not to be associated with disease activity or severity.

Adrenocortical tumors: results of treatment and study of Weiss's score as a prognostic factor

PURPOSE: The differential diagnosis between benign and malignant adrenal cortical tumors circumscribed to the gland is controversial. One hundred and seven patients with adrenal cortex tumors (excluding those with primary hyperaldosteronism) were studied to assess the 5-year survival rate of adults, children, patients stratified by pathological stage, and patients stratified according to Weiss's score of <3 or >3. METHODS: The patients were evaluated both clinically and biochemically. One hundred and five patients underwent surgery and were classified pathologically as stages I, II, III, or IV. The tumors were weighed, measured, and classified according to Weiss's criteria and divided into 2 groups: <3 and >3. RESULTS: After 5 years, the survival rate was 77.5% for the whole group, 74.61% for the adults, 84.3% for the children, 100% for stage I, 83.9% for stage II, 33% for stage III, and 11.7% for stage IV groups. Additionally, after 5 years, 100% of the patients with tumors with Weiss's score <3 were alive compared to 61.65% of those with Weiss's score >3. The average weights of the tumors of score <3 and >3 were 23.38 g ± 41.36 g and 376.3 ± 538.76 g, respectively, which is a statistically significant difference. The average sizes of tumors of Weiss's score <3 and >3 were 3.67 ± 2.2 cm and 9.64 ± 5.8 cm, respectively, which is also a statistically significant difference. CONCLUSIONS: Weiss's score may be a good prognostic factor for tumors of the adrenal cortex. Additionally, there was a statistically significant difference between the average weight and size of tumors with benign behavior (Weiss's score <3) and those with malignant behavior (Weiss's score >3).

Understanding multi-asset factor models: Factor exposure interpretation

Field lab: Business project

Tensile creep of a structural epoxy adhesive: experimental and analytical characterization

Epoxy adhesives are nowadays being extensively used in Civil Engineering applications, mostly in the scope of the rehabilitation of reinforced concrete (RC) structures. In this context, epoxy adhesives are used to provide adequate stress transference from fibre reinforced polymers (FRP) to the surrounding concrete substrate. Most recently, the possibility of using prestressed FRPs bonded with these epoxy adhesives is also being explored in order to maximize the potentialities of this strengthening approach. In this context, the understanding of the long term behaviour of the involved materials becomes essential. Even when non-prestressed FRPs are used a certain amount of stress is permanently applied on the adhesive interface during the serviceability conditions of the strengthened structure, and the creep of the adhesive may cause a continuous variation in the deformational response of the element. In this context, this paper presents a study aiming to experimentally characterize the tensile creep behaviour of an epoxy-based adhesive currently used in the strengthening of concrete structures with carbon FRP (CFRP) systems. To analytically describe the tensile creep behaviour, the modified Burgers model was fitted to the experimental creep curves, and the obtained results revealed that this model is capable of predicting with very good accuracy the long term behaviour of this material up to a sustained stress level of 60% of the adhesive’s tensile strength.

Analysis of polydicyclopentadiene-metal hybrid adhesive joints for automotive exterior body applications

An exterior body panel solution containing a polydicyclopentadiene skin attached to an interior metallic reinforcement through adhesive bonding is being studied to be applied in the MobiCar bonnet. With this solution is expected to achieve lightness, adequate structural integrity and cost-efficiency. However, there is uncertainty regarding to the bonnet adhesiveness since different metallic materials and adhesive types are being considered for its development. Thus, in this paper, several samples are tested through shear loading with the aim of understanding the loading magnitude expected by using polydicyclopentadiene, steel DC04+ZE and aluminum alloy AW5754-H111 as substrates adhesively bonded by an epoxy or a methacrylate. Methacrylate adhesive have shown greater shear strength in all types of adhesive joints. PDCPD joints presented the highest displacements. Surface degradation was considered adequate over abrading once none strength difference was seen between the different surface treatments. Steel treated by cataphoresis has shown the highest joint interface strength.