Regensburg, Universiẗat, Diss., 2009.

Thesis (M.S.)--Oregon State College, 1960. / Typescript. Includes bibliographical references (leaves 57-58). Also available on the World Wide Web.

Arthritis deformans in its atrophic form (rheumatoid arthritis) is, perhaps, best defined as a chronic disease affecting many joints, principally the smaller ones. It occurs chiefly in the female sex, is due probably to the action of a toxin, and is characterised by changes in the cartilages and the soft structures surrounding the joints, thus causing great immobility and deformity. That arthritis is a disease of great antiquity is borne out by the fact that recently-unearthed bones from tombs of about 3700-1300 B.C. showed unmistakable evidence of the affection. In exarnination of remains in Egypt, remains representative of all periods from early predynastic times dovm to the Fifth Dynasty after Christ, "the disease which showed itself with by far the greatest frequency in the bodies of all periods is rheumatoid arthritis". Virchow has left records describing the affection in bones unearthed from Pompeii. From these remote times onwards through the Middle Ages to the present day, an almost continuous series of historical records testifies that the disease has always been with us, and also that its clinical characters have remained unaltered through all the ages. The aetiology and pathology of the disease have, however, been so shrouded in darkness that we find the various writers, in their information on the subject, making indiscriminate use of the terms rheumatism, gout and arthritis to designate this affection.

Paget's disease of bone (PDB) is characterised by focal lesions of increased bone turnover driven by overactive osteoclasts, which often contain nuclear and cytoplasmic inclusion bodies. Mutations affecting the sequestosome-1 (SQSTM1) ubiquitin-associated (UBA) domain have been identified in individuals with PDB. SQSTM1, also known as p62, is a ubiquitously expressed multidomain scaffold protein of 62 kDa that functions in multiple signalling pathways important for cell survival and osteoclast activity. The mechanisms by which SQSTM1 mutations cause PDB remain unclear. Using immunohistochemistry, I showed evidence that protein degradation pathway components, both from the UPS and the autophagy pathway, are elevated in osteoclasts in patients with PDB compared with control osteoclasts from patients without PDB. Using molecular and microscopical methods to examine Pagetic bone biopsies, osteoclast cultures and various cell lines, I have identified two isoforms of SQSTM1. In all cell types examined, four SQSTM1 transcripts were detected, differing in their 5′-untranslated region; one transcript encodes p62, while the other three encode a 55 kDa isoform of SQSTM1. The newly identified isoform also contains the UBA domain mutated in PDB. Using biochemical and microscopical methods, I found that both SQSTM1 isoforms are degraded by autophagy. The isoforms interact with each other and form aggregates upon autophagy inhibition. SQSTM1-55 is ~21× more abundant in osteoclasts than SQSTM1/p62. Biochemical and microscopical methods showed that PDB-causing mutations in SQSTM1/p62 impair its autophagic degradation. Cell lines expressing SQSTM1/p62 mutations form paracrystalline inclusion bodies that by immuno-transmission electron microscopy (TEM) were found to contain SQSTM1 and ubiquitin and were ultrastructurally identical to those found in PDB. As observed by TEM, these inclusions can be degraded by autophagy. The effects of mutations in SQSTM1-55 have yet to be characterised. Abstract Taken together, these data show that mutations in SQSTM1 isoforms impair protein degradation and can lead to inclusion body formation suggesting that PDB results from dysregulated protein degradation in osteoclasts.

No description available.

Dissertation (Ph.D.) --University of Texas Graduate School of Biomedical Sciences at San Antonio, 2008. / Vita. Includes bibliographical references.

Objective: Rheumatoid arthritis (RA) is a chronic, systemic, inflammatory autoimmune disease. Enhanced B cell activity has been proposed in the pathogenesis of RA along with different pro-inflammatory cytokines such as interleukin 6 (IL-6) and tumor necrosis factor alpha (TNF-α), critically involved in chronic inflammation. Biological agents targeting these cytokines IL-6 and TNF-α have considerably advanced treatment of autoimmunity. Enhanced B cell activity, particularly memory B cells gained particularly interest in evaluating response during therapies from biologics. Human peripheral memory B cells can be distinguished by the phenotypic expression of CD27 and IgD defining three major B cell subpopulations: CD27+IgD+ pre-switch, CD27+IgD- post-switch and CD27-IgD- double negative (DN) memory B cells. Therefore, we analyzed different memory populations during cytokine inhibition by using tocilizumab (anti-IL-6R, TCZ) and adalimumab (anti-TNF-α, ADA), with focus on DN B cells Suspended. DN B cells lacking the conventional memory marker CD27, but due to their mutational Ig repertoire (IgR) considered in the memory compartment. However, only scare data are available for this DN subpopulation in RA. Methods: Phenotype analysis of activation markers (CD95 and ki-67) of B cell and their subsets were compared in RA patients (median age ~56 years) and in HD. DN memory B cells were phenotypically analyzed from RA patients during IL-6R or TNF-α inhibition at baseline week 12, week 24 and 1 year. Single B cell PCR approach was used to study Ig- receptors VH genes and isotype specific genes. Nonparametric Wilcoxon matched pair test and Mann-Whitney U test was used for statistical analysis by using GraphPadPrism 5. Univariate logistic regression was used to calculate odd ratios and correlation using Pearson r using SPSS statistics 22. Results: Surface and intracellular staining of B cells showed a significantly higher percentage of CD95 and ki-67 expressions in RA, which was highest in post-switch memory B cells followed by pre-switch and DN memory B cells. During cytokines (IL-6R & TNF-α) inhibition, both CD95 and ki-67 expression were significantly reduced at week 12 and 24 along with reduction in their clinical parameters like DAS28, CRP, ESR. Furthermore, the phenotypic analysis in 107 RA patients and 49 healthy donors (HD) showed a significantly expanded population of DN B cells in RA which contain a heterogeneous mixture of IgA, IgG and IgM expressing cells with a clear dominance of IgG+ cells. Pre-therapy analysis of rearranged IgR sequences from patients (n=9) revealed that DN B cells carry rearranged heavy chain gene sequences with a diversified mutational pattern consistent with memory B cells. In contrast to tumor necrosis factor alpha (TNF-alpha) inhibition, a significant reduction in mutational frequency of BCR gene rearrangements at week 12, 24 and 1 year (p < 0.0001) was observed by in vivo IL-6R inhibition. These changes were observed for all BCR isotypes IgG, IgA and IgM at week 12, 24 and 1 year (p < 0.0001). IgA-RF, IgA serum level and IgA+ DN B cells decreased significantly (p < 0.05) at week 12 and week 24 during TCZ. Patients with a good European league against rheumatism (EULAR) response to TCZ had less DN B cells at baseline as compared to moderate responders (p = 0.006). Univariate logistic regression analysis revealed that the frequency of DN B cells at baseline is inversely correlated to a subsequent good EULAR response (p = 0.024) with an odds ratio of 1.48 (95% confidence interval as 1.05-2.06). Conclusion: Both anti-TNF-α and anti-IL-6R could reduce higher B cell activity and improve disease activity tremendously in RA patients. The heterogeneous DN B cell compartment is expanded in RA and dominated by IgG isotype. TCZ can modulate the mutational status of DN Ig isotype receptors over 1 year. Interestingly, the frequency of DN B cells in RA may serve as a baseline predictor of subsequent EULAR response to TCZ. / Die rheumatoide Arthritis (RA) ist eine chronische, systemische, und entzündliche Autoimmunerkrankung. Es wird angenommen, dass neben verschiedenen inflammatorischen Zytokinen wie beispielsweise Interleukin-6 (IL-6) und Tumor Nekrose Faktor alpha (TNF-α) auch eine verstärkte Aktivität von B-Zellen in chronischen Entzündungsprozessen involviert ist. Biologische Agenzien, die gezielt gegen die Zytokine IL-6 und TNF-α gerichtet sind, haben die Behandlungsmöglichkeiten der Autoimmunerkrankungen wesentlich vorangetrieben. Derzeit rückt eine verstärkte B-Zell Aktivität, insbesondere die von Gedächtnis B-Zellen, bei der Evaluierung von Reaktionen auf biologische Therapien in den Focus des Interesses. Humane periphere Gedächtnis B-Zellen können anhand der Expression von CD27 und IgD phänotypisch charakterisiert werden und lassen sich dadurch in drei Subpopulationen einteilen: CD27+IgD+ prä-switch, CD27+IgD- post-switch und CD27-IgD- doppelt negative (DN) Gedächtnis B-Zellen. Wir untersuchten die verschiedenen Gedächtnis B-Zell-Populationen während der Zytokininhibierung mittels Tocilizumab (anti-IL-6R, TCZ) und Adalimumab (anti-TNF-α, ADA), wobei der Focus auf DN B-Zellen lag. DN B-Zellen fehlt der konventionelle Gedächtniszellen-Marker CD27, sie werden aber aufgrund ihres mutierten Ig-Repertoires (IgR) den Gedächtniszellen zugeordnet. Für diese DN B-Zell Subpopulation gibt es allerdings bislang nur wenige Daten im Zusammenhang mit RA. Die B-Zell Subpopulationen von RA Patienten (durchschnittliches Alter ~56 Jahre) und gesunden Spendern (englisch: healthy donors, HD) gleichen Alters als Kontrolle, wurden hinsichtlich der Aktivierungsmarker, CD95 und ki-67, phänotypisch analysiert und verglichen. DN Gedächtnis B-Zellen von RA Patienten wurden phänotypisch zu Beginn der IL-6R oder TNF-α Inhibition, nach 12 und 24 Wochen sowie 1 Jahr nach Behandlungsbeginn bestimmt. Es wurden Einzel-PCR Analysen von B-Zellen durchgeführt, um die VH Gene der Ig-Rezeptoren und spezifische Gene zu typisieren. Für die statistischen Auswertungen wurde in GraphPad Prism 5 der‚nonparametric Wilcoxon matched pair test‘ und der‚ Mann-Whitney U test‘ verwendet. Die eindimensionale logistische Regression wurde angewandt, um Odd-Ratio und Korrelationen mittels Pearson r in SPSS Statistik 22 zu berechnen. Die phänotypische Analyse der Oberflächen und intrazellulären Färbungen der B-Zellen ergab einen signifikant erhöhten Prozentsatz der CD95 und ki-67-Expression in RA-Patienten, wobei die Expression am höchsten in post-switch Gedächtnis B-Zellen, gefolgt von prä-switch und DN Gedächtnis B-Zellen, war. Während der Zytokin-Inhibierung (IL-6R & TNF-α) war sowohl die CD95 als auch ki-67-Expression zum Zeitpunkt Woche 12 und Woche 24 signifikant reduziert, einhergehend mit der Verringerung klinischer Parameter wie DAS28, CRP und ESR. Weiterhin zeigte die phänotypische Analyse von 86 RA-Patienten und 49 HD eine deutlich expandierte DN B-Zell Population in RA-Patienten. Diese setzte sich aus einer heterogenen Mischung von IgA, IgG und IgM exprimierenden Zellen zusammen, wobei IgG+ B-Zellen deutlich dominierten. Die Analyse von neu-gruppierten IgR Sequenzen von B-Zellen aus RA Patienten (n=9) vor Therapiebeginn zeigte, dass DN B-Zellen umgruppierte Gensequenzen der schweren Ketten mit diversen Mutationsmustern tragen, wie es bei Gedächtnis B-Zellen der Fall ist. Im Gegensatz zur TNF-α-Hemmung ist bei der in vivo IL-6R-Inhibierung eine signifikante Reduktion der Mutationsrate innerhalb der umgruppierten der Gene der B-Zell Rezeptoren (BCR) nach 12 und 24 Wochen sowie nach 1 Jahr (p<0,0001) zu beobachten. Diese Änderungen waren bei allen BCR Isotypen IgG, IgA und IgM bei Woche 12, 24 und 1 Jahr (p<0.0001) zu sehen. IgA-RF, IgA-Serum Spiegel sowie IgA+ DN B Zellen nahmen 12 und 24 Wochen nach Beginn der Behandlung mit TCZ signifikant ab (p<0,05). Patienten mit einer guten klinischen Besserung (EULAR Antwort) auf TCZ hatten weniger DN B-Zellen vor Therapiebeginn im Blut als Patienten, die eine moderate Reaktion zeigten. Univariate logistische Regressionsanalysen zeigten, dass die Frequenz von DN B-Zellen vor Therapiebeginn invers mit einer sich anschließenden guten EULAR Antwort korreliert. Die Odds Ratio war 1,48 (95% Konfidenz Intervall wie 1,05-2,06). Im Ergebnis hat die Studie Phänotypen von aktivierten Gedächtnis B-Zellen und deren Untergruppen in Patienten mit aktiver RA nachgewiesen. Die höhere Expression des Oberflächenmarker CD95 und des intrazellulären Marker ki-67 spiegelt die Krankheitsaktivität wieder und korreliert mit dieser positiv. Signifikant höhere Populationen von CD27-IgD- DN B-Zellen in der RA stehen jedoch unabhängig von der Krankheitsaktivität in Bezug zum Ansprechen auf die Therapie. Diese erhöhten DN B-Zellen sind eine Mischung aus somatisch mutierten Isotyp IgG, IgA und IgM exprimierenden Zellen, wobei IgG Isotypen dominieren. Die TCZ Therapie bewirkt insbesondere eine Abnahme der Frequenzen von IgA+ DN Gedächtnis B-Zellen, zusammen mit einer Abnahme des Serum-IgA und RF-IgA-Spiegels. Auf molekularer Ebene ist zu sehen, dass mutierte DN B Zellen geringere Mutationen aufweisen als prä-switch und post-switch B-Zellen. Interessanterweise sind IgA+ DN B-Zellen am meisten unter allen 3 Isotypen mutiert. Die TCZ Therapie reduziert die Mutationsrate, auch innerhalb der RGYW Hotspots, in allen DN B-Zell Isotypen über einen Zeitraum von einem Jahr. Eine geringe Anzahl von DN Gedächtnis B-Zellen vor Therapiebeginn mit TCZ (anti-IL-6R) war mit einer verbesserten klinischen Antwort korreliert. Auf Grundlage dieser aktuellen Ergebnisse erscheinen DN Gedächtnis B-Zellen als möglicher Biomarker Kandidaten zu sein, um eine Reaktion auf eine TCZ Therapie anzuzeigen.

Paget's disease of the bone is a skeletal disorder of unknown cause. This disease is characterised by excessive and abnormal bone remodelling brought about by increased bone resorption followed by disorganised bone formation. Increased bone turnover results in a disorganised mosaic of woven and lamellar bone at affected skeletal sites. This produces bone that is expanded in size, less compact, more vascular, and more susceptible to deformity or fracture than normal bone. Symptoms of Paget's disease may include bone pain, bone deformity, excessive warmth over bone from hypervascularity, secondary arthritis, and a variety of neurologic complications caused in most instances by compression of the neural tissues adjacent to pagetic bone. Genetic factors play a role in the pathogenesis of Paget's disease but the molecular basis remains largely unknown. The identification of the molecular basis of Paget's disease is fundamental for an understanding of the cause of the disease, for identifying subjects at risk at a preclinical stage, and for the development of more effective preventive and therapeutic strategies for the management of the condition. With this in mind, the aim of this project is to identify genetic loci, in a large pedigree, that may harbour genes responsible for Paget's disease of bone. A large Australian family with evidence of Paget's disease was recruited for these studies (Chapter 3). This pedigree has characterised over 250 individuals, with 49 informative individuals affected with Paget's disease of bone, 31 of whom are available for genotypic analysis. The pattern of disease in these individuals is polystotic, with sites of involvement including the spine, pelvis, skull and femur. Although the affected individuals have a severe early-onset form of the disease, the clinical features of the pedigree suggest that the affected family members have Paget's disease and not familial expansile osteolysis (a disease with some similarities to Paget's disease), as our patients have extensive skull and axial skeletal involvement. The disease is inherited as an autosomal dominant trait in the pedigree with high penetrance by the sixth decade. Due to the large size of this family and multiple affected members, this pedigree is a unique resource for the detection of the susceptibility gene in Paget's disease. The first susceptibility loci for Paget's disease of bone have been mapped by other investigators to chromosome 6p21 (PDB1) and 18q21.1-q22 (PDB2) in different pedigrees. Linkage analysis of the Australian pedigree in these studies was performed with markers at PDB1: these data showed significant exclusion of linkage, with LOD scores < - 2 in this region (Chapter 4). Linkage analysis of microsatellite markers from the PDB2 region excluded linkage with this region also, with a 30 cM exclusion region (LOD score < -2.0) centred on D18S42 (Chapter 4). This locus on chromosome 18q21.1-q22 contains a serine protease (serpin) cluster with similarities to chromosome 6p21. Linkage analysis of this region also failed to provide evidence of linkage to this locus (Chapter 4). These data are consistent with genetic heterogeneity of Paget's disease of bone. A gene essential for osteoclast formation encoding receptor activator of nuclear factor-kB (RANK), TNFRSF11A, has been previously mapped to the PDB2 region. Mutations in the TNFRSF11A gene have been identified segregating in pedigrees with Familial Expansile Osteolysis and early onset familial Paget's disease, however, linkage studies and mutation screening have excluded the involvement of RANK in the majority of Paget's disease patients. For the Australian pedigree, mutation screening at the TNFRSF11A locus revealed no mutations segregating with affected individuals with Paget's disease (Chapter 4). Based on these findings, our hypothesis is that a novel susceptibility gene relevant to the pathogenesis of Paget's disease of bone lies elsewhere in the genome in the affected members of this pedigree; this gene should be identifiable using a microsatellite genome-wide scan followed by positional cloning. A genome-wide scan of the Australian pedigree was carried out, followed by fine mapping and multipoint analysis in regions of interest (Chapter 5). The peak 2-point LOD scores from the genome-wide scan were LOD = 2.75 at D7S507 and LOD = 1.76 at D18S70. Two additional regions were also considered for fine mapping: chromosome 19p11-q13.1 with a LOD of 1.58 and chromosome 5q35-qter with a LOD of 1.57. Multipoint and haplotype analysis of markers flanking D7S507 did not support linkage to this region (Chapter 5). Similarly, fine mapping of chromosome 19p11-q13.1 failed to support linkage to this region (Chapter 5). Linkage analysis with additional markers in the region on chromosome 5q35-qter revealed a peak multipoint LOD score of 6.77 (Chapter 5). A distinct haplotype was shown to segregate with all members of the family, except the offspring of III-5 and III-6. Haplotype analysis of markers flanking D18S70 demonstrated a haplotype segregating with Paget's disease in a large sub-pedigree (descendants of III-3 and III-4) (Chapter 5). This sub-pedigree had a significantly lower age at diagnosis than the rest of the pedigree (51.2 + 8.5 vs. 64.2 + 9.7 years, p = 0.0012). Linkage analysis of this sub-pedigree demonstrated a peak two-point LOD score of 4.23 at marker D18S1390 (q = 0.00), and a peak multipoint LOD score of 4.71, at marker D18S70. An implication of these data is that 18q23 harbours a novel modifier gene for reducing the age of onset of Paget's disease of bone. A number of candidate Paget's genes have previously been identified on chromosome 18q23, including the nuclear factor of activated T cells (NFATc1), membrane-associated guanylated kinase (MAGUK) and a zinc finger protein. Candidate gene sequencing of these genes in these studies has failed to identify mutations segregating with affected family members in the sub-pedigree linked to chromosome 18q23 (Chapter 6). More recently, a mutation in the gene encoding the ubiquitin-binding protein sequestosome 1 (SQSTM/p62) has been shown to segregate with affected members of Paget's disease families of French-Canadian origin. In this study, a single base pair deletion (1215delC) was identified as segregating with the majority of affected members in the pedigree (Chapter 6). This deletion introduces a stop codon at amino acid position 392 which potentially results in early termination of the protein and loss of the ubiquitin binding domain. The three affected members of the family that do not share the affected haplotype do not carry a mutation in the coding region of SQSTM/p62. Screening of affected members from 10 further Paget's disease families identified the previously reported P392L mutation in 2 (20%) families. No SQSTM1/p62 coding mutations have been found in the remaining 8 families or in 113 aged matched controls. In conclusion, this project has identified genetic loci and mutations that segregate with individuals affected with Paget's disease. Further investigation of the functional significance of the genetic changes at these loci is expected to lead to a better understanding of the molecular basis of this disease.

Undergraduate honors paper--Mount Holyoke College, 2007. Dept. of Art. / CD-Rom includes images of art work. Includes bibliographical references (leaf 12).

Orientadores: Anelyssa Cysne Frota D'Abreu, Iscia Teresinha Lopes-Cendes / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Ciências Médicas / Made available in DSpace on 2018-08-25T05:40:31Z (GMT). No. of bitstreams: 1 Piovesana_LuizaGonzaga_M.pdf: 1656872 bytes, checksum: 2a3571bb0d9dc43e8f0405aa2c799a5e (MD5) Previous issue date: 2014 / Resumo: As distonias caracterizam-se por movimentos involuntários e torsionais, que se manifestam de diferentes formas e podem afetar quaisquer músculos voluntários. Diversas mutações genéticas foram associadas às distonias primárias, destacando-se a DYT1, DYT5 e DYT6. O gene DYT1/TOR1A foi o primeiro identificado, ao apresentar uma deleção GAG que produz uma proteína mutante que altera conexões núcleo-cito-esqueléticas e o processamento proteico. O fenótipo típico inicia-se dos três aos 26 anos, tem penetrância de 30%, sendo 60% com acometimento generalizado ou multifocal. O gene DYT6/THAP1 possui diversos polimorfismos descritos e acredita-se que seja o segundo em prevalência entre as distonias hereditárias. Possui penetrância ainda menor e fenótipo de início precoce, envolvimento crânio-cervical e de fala. A frequência, etiologia e as alterações genéticas das distonias não são conhecidas na população brasileira, que por suas características específicas, não podem ter os resultados de outras populações simplesmente transpostos para a nossa. Nosso objetivo, portanto, foi caracterizar genética e clinicamente uma amostra de pacientes brasileiros com distonia. Os indivíduos foram recrutados no Ambulatório de Distúrbios do Movimento e de Distonia. Os pacientes foram avaliados por um questionário padronizado, seguido por pesquisa das mutações DYT1 e DYT6. A avaliação clínica demonstrou que a nossa coorte apresenta padrão semelhante ao internacional, com pacientes de início jovem tendendo a apresentar quadros generalizados e com história familiar positiva e pacientes adultos mantendo quadros focais ou segmentares e esporádicos. A pesquisa de mutações identificou 1 mutação missense já descrita na literatura, envolvida na penetrância da DYT1 em indivíduos com a mutação causadora clássica da doença e que pode conferir risco quando encontrada isoladamente. Também encontramos uma deleção de 6 pares de base no fim do exon 1 do gene THAP1 que em avaliações preliminares altera o sitio de splicing e acaba por abortar a tradução da proteína por meio de um stop códon precoce. Concluímos que nossos pacientes tem apresentação clinica semelhante a literatura mundial, porém com características genotípicas diferentes, pois não encontramos em nenhum individuo as mutações mais classicamente associadas as doenças. A diferenciação das distonias em subtipos e o entendimento das vias moleculares comuns devem fazer parte de investigações futuras / Abstract: Dystonia is characterized by involuntary and torsional movements, which manifest themselves in various forms and can affect any voluntary muscle. Several genetic mutations have been associated with isolated hereditary dystonia, most notably the DYT1 and DYT6. The DYT1 is caused by a GAG deletion at the TOR1A gene, which produces a protein that alters intracellular membranes connections and protein processing. The typical phenotype starts from three to 26 years of age, it has penetrance of 30 % and 60% of the subjects will progress to a generalized or multifocal involvement. The DYT6/THAP1 gene has several polymorphisms described, believed to be the second in prevalence among the hereditary dystonias. DYT6 has an even lower penetrance. It is characteristically an early-onset, dystonia with craniocervical and speech involvement. The frequency, etiology and genetic alterations of dystonia are not known in the Brazilian population, which due to its specific characteristics may not share of the same genetic background. Our aim was to evaluate genetically and clinically a sample of Brazilian patients with dystonia. Subjects were recruited from the Outpatient Movement Disorders and Dystonia Clinics. Patients were assessed by a standardized questionnaire, followed by molecular testing for DYT1 and DYT6. Our cohort showed similar results with the literature, where young, generalized and positive family history commonly group together, as focal and segmental cases that appear in adulthood tend to stabilize. Sequencing of the DYT1 gene found a known missense mutation that contributes to low penetrance in individual with the typical DYT1 mutation but might be a risk factor when found in isolation. Sequencing of the DYT6 gene showed a novel 6bp deletion at the end of exon 1, causing alternate splicing and a premature stop codon in preliminary analysis. Subdividing phenotypes and understanding common molecular pathways through new genetic data is in the future of dystonia research / Mestrado / Fisiopatologia Médica / Mestra em Ciências