A displasia frontonasal (DFN) compreende quadros de aparência facial variável, sendo clinicamente caracterizada por dois ou mais dos seguintes sinais: hipertelorismo ocular com consequente alargamento da base nasal; fissura facial mediana afetando o nariz ou o nariz e lábio superior e, por vezes, o palato; fissura alar (uni ou bilateral); ponta nasal ausente; crânio anterior bífido oculto, e implantação em 'V' dos cabelos na fronte. A DFN pode ser vista como um defeito de desenvolvimento que pode ocorrer por si só ou como parte do quadro clínico de várias síndromes. A maioria dos casos de DFN é esporádica, e em raras circunstâncias foram observadas alterações cromossômicas em alguns indivíduos. Até o momento, quatro genes foram relacionados à patogênese molecular de algumas das síndromes com DFN, EFNB1, associado a uma forma de DFN ligada ao X e os genes ALX1, ALX3 e ALX4, todos associados a formas de DFN com herança autossômica recessiva. Embora esteja claro haver heterogeneidade etiológica, na maioria dos casos de DFN a causa não é conhecida, dificultando o adequado aconselhamento genético aos pacientes e seus familiares. Sendo assim, realizamos estudos com diferentes estratégias metodológicas buscando melhor compreender as possíveis causas genéticas da DFN. Ao todo foram analisados 10 pacientes: um caso familial de DFN leve com herança aparentemente autossômica dominante, um caso clinicamente sugestivo de mutação em ALX1, e oito casos de DFN associada a atraso de desenvolvimento com ou sem outras anomalias, dos quais um apresentava um rearranjo de novo aparentemente balanceado entre os cromossomos 4 e 12. Optamos por realizar sequenciamento dos genes previamente relacionados a fenótipos com DFN em todos os casos; para aqueles em que não foram detectadas mutações patogênicas, realizamos análise de variações de número de cópias (CNV) por microarray de polimorfismos de base única e, para o paciente com rearranjo cromossômico, realizamos o mapeamento do ponto de quebra por hibridação in situ fluorescente. Constatamos uma mutação em heterozigose no gene ALX4 co-segregando com o fenótipo do caso familial, sendo esta a primeira descrição de alteração em tal gene causando uma forma de DFN com herança dominante, e sugerimos pela primeira vez um mecanismo de dominância negativa. No caso sugestivo de mutação em ALX1, o diagnóstico foi confirmado através da identificação de uma mutação em homozigose neste gene do paciente; este caso consiste no 3o da literatura mundial e evidencia pela primeira vez que mutações em ALX1 não necessariamente levam a atraso de desenvolvimento ou deficiência intelectual. Os estudos citogenéticos e moleculares dos pontos de quebra do paciente com rearranjo cromossômico sugeriram os genes ARAP2 e CAND1 como possíveis responsáveis por seu quadro clínico, enquanto o estudo de CNVs nos indivíduos com DFN associada a atraso de desenvolvimento apontou os genes DNAJB12 e ENOX2 como possíveis candidatos para explicar o fenótipo de dois dos pacientes. É preciso que novos estudos sejam realizados a fim de melhor compreender o significado de tais achados e a real contribuição de cada gene para o desenvolvimento craniofacial humano e para a etiologia da DFN. Para os casos em que não foram identificadas alterações conclusivas no presente estudo, embora causas ambientais não possam ser descartadas, é preciso que seja investigada também a existência de fatores genéticos e epigenéticos não detectáveis pelas metodologias utilizadas, bem como a hipótese de mosaicismo somático. Nossos resultados, além de corroborarem o envolvimento dos genes ALX1 e ALX4 em fenótipos com DFN, sugerem também novos genes candidatos: ARAP2, CAND1, DNAJB12 e ENOX2 / Frontonasal dysplasia (FND) is a rare group of disorders that comprises cases with a variety of facial appearances, and is clinically characterized by two or more of the following signs: ocular hypertelorism with consequent broadening of the nasal root; median facial cleft affecting the nose and/or upper lip and palate; clefting of the alae nasi (uni or bilateral); lack of formation of the nasal tip; anterior cranium bifidum occultum; and a V-shaped frontal hairline. FND is a developmental defect that can occur alone or as part of several syndromes. Most cases of FND are sporadic, and in rare circumstances chromosomal alterations were observed in affected individuals. To date, four genes have been related to the molecular pathogenesis of some syndromes with DFN, one (EFNB1) is associated with an X-linked form while the 3 others (ALX1, ALX3 and ALX4) are associated with autosomal recessive forms. Although it is clear that FND is etiologic heterogeneous, the causative mechanism is unknown in most cases which makes it hard to give proper genetic counseling to patients and their families. In order to get new insights into the genetic mechanisms leading to FND, we performed studies with different methodologies. Altogether, 10 patients were analyzed: a familial case of a mild form of FND with an apparently autosomal dominant inheritance pattern, a case clinically suggestive of mutation in ALX1, and eight cases of FND associated with developmental delay with or without other anomalies, one of which with an apparently balanced de novo rearrangement between chromosomes 4 and 12. We chose to sequence the genes previously associated with FND phenotypes in all cases; for those in which pathogenic mutations were not detected, we conducted an analysis of copy number variations (CNV) by single nucleotide polymorphisms microarrays; for the patient with chromosomal rearrangement, we also mapped the breakpoints by using fluorescence in situ hybridization. We found a heterozygous mutation in ALX4 co-segregating with the phenotype of the familial case; this is the first description of mutation in this gene causing a form of FND with dominant inheritance pattern, and we suggested for the first time a dominant negative mechanism. In the case suggestive of mutation in ALX1, the diagnosis was confirmed by the identification of a homozygous mutation in this gene; this is the third case of the literature and shows for the first time that mutations in ALX1 are not necessarily related to developmental delay or intellectual disability. Breakpoints cytogenetic and molecular studies done with the patient with chromosomal rearrangement suggested ARAP2 and CAND1 genes as causative candidates for his condition, while the study of CNVs in individuals with FND associated with developmental delay pointed DNAJB12 and ENOX2 genes as possible candidates to explain the phenotypes of two of the patients. Further studies are necessary to better understand the significance of such findings and the actual contribution of each of these genes to human craniofacial development and the etiology of FND. Although environmental causes cannot be ruled out, it should also be investigated the existence of genetic and epigenetic factors as well as the possibility of somatic mosaicism, among the cases negative for the molecular approaches used in our study. Our results corroborate the involvement of ALX1 and ALX4 in FND phenotypes, and suggest new candidate genes: ARAP2, CAND1, DNAJB12 and ENOX2.

É estudada, conceitualmente a técnica de recapeamento de quadril de cães como modelo cirúrgico. A artroplastia do quadril foi desenvolvida com a finalidade de estabelecer a mobilidade articular e também no alívio da dor de pacientes humanos. Em animais, principalmente os cães, a artroplastia total, é um procedimento cirúrgico muito utilizado na articulação coxofemoral para a correção de patologias de quadril, sejam elas degenerativas traumáticas ou inflamatórias além de aliviar a dor. A artroplastia de recapeamento de quadril em humanos tem se mostrado uma técnica muito eficiente por estar próxima da anatomia natural do quadril e tem sido aplicada em pacientes jovens e ativos. A vantagem de se realizar a técnica de recapeamento é que nesta, há uma ressecção mínima da cabeça femoral e que promove uma melhora em relação à estabilidade da articulação, entretanto essa técnica ainda não é aplicada em animais. O presente trabalho tem por objetivo estudar a técnica de recapeamento de quadril de cães de forma análoga as técnicas aplicadas em humanos e também, propor um projeto de ferramental cirúrgico específico em conjunto com o protocolo cirúrgico. A técnica conceitual de artroplastia de recapeamento de quadril de cães foi desenvolvida a partir de um fêmur canino onde foram desenvolvidos os conceitos da técnica cirúrgica e o protótipo do ferramental cirúrgico necessário para o desenvolvimento desta técnica. Inicialmente foram feitas aquisições das imagens dos objetos do trabalho (fêmur canino, ferramental cirúrgico e prótese cirúrgica) que foram convertidas em arquivos CAD; a partir destes foram gerados cópias em gesso através do processo de impressão 3D do ferramental cirúrgico desde o guia de furação até a fresa de chanframento e também da prótese cirúrgica de recapeamento. A fabricação do ferramental cirúrgico obtido pelo processo de impressão 3D possibilitou uma análise visual dos protótipos que serviram de modelos para a fabricação do ferramental cirúrgico definitivo, sendo este, confeccionado em aço. Isso permitiu sua validação em bancada de laboratório através de testes realizados em modelos de ossos de cães em resina. Conclui-se que a técnica de recapeamento de quadril de cães validada em bancada de laboratório poderá ser realizada em conjunto com o ferramental cirúrgico proposto para em um futuro muito próximo ser usado em articulações de cães portadores de displasia coxofemoral devido a sua funcionalidade e à demanda de casos clínicos para este procedimento. A técnica cirúrgica de recapeamento estudada poderá ser oferecida a população a um custo acessível por ser inovadora e promissora no contexto da ortopedia veterinária. / The study conceptually describes a surgical model for dog hip resurfacing technique. Hip arthroplasty was developed to restore joint mobility and relieve of human patients pain. In animals, especially dogs, total arthroplasty is a surgical procedure commonly used to correct traumatic, degenerative and inflammatory hip diseases and alleviate pain. The resurfacing hip arthroplasty in humans, applied in young and active patients, has shown to be an efficient technique. The advantage of using this technique is that there will be a minimal resection of the femoral head, improving the stability of the joint; however it has not been applied to animals yet. The present dissertation reports on the study of hip resurfacing technique for dogs in a similar way it is applied in humans. It also proposes a specific surgical tooling design in conjunction with the surgical protocol. The technical concept of hip resurfacing arthroplasty for dogs was developed from a canine femur from which the concepts of the surgical technique and the prototypes of the necessary surgical tools were developed. Initially, images of the objects used in the work (canine femur, surgical tools and surgical prosthesis) were acquired. They were then converted into CAD files, which generated plaster copies of surgical tools, from the hole guide to the to cutter and chamfer, and also surgical resurfacing prosthesis through the 3D printing process. The manufacture of the surgical tools models obtained by 3D printing process allowed a visual analysis of the prototypes that served as references for the definitive surgical tool made in steel. Such tools were validated by means of laboratory bench tests using resin models of dogs\' bones. It was possible to conclude that the technique of hip resurfacing in dogs can be employed in conjunction with the proposed surgical tools in the joints of dogs with hip dysplasia in a very near future. Due to its full functionality and large demand of clinical cases for this procedure, the technique may be offered to the population at an affordable cost. It is also an innovative and promising technique in the context of veterinary orthopedics.

Mutations in genes of importance for cartilage development may lead to skeletal malformations, chondroskeletal dysfunction and increased susceptibility to degenerative joint disease. Characterization of these mutations and identification of molecular pathways for the corresponding gene products have contributed to our understanding of mechanisms regulating skeletal patterning, endochondral ossification and joint formation. A five generation family segregating autosomal dominant osteochondritis dissecans (OCD) was identified. Affected family members presented with OCD in knees, hips and elbows, short stature, and early osteoarthritis. A genome wide scan and a multipoint linkage analysis identified aggrecan (ACAN) as a prime candidate gene. DNA sequence analysis of the ACAN-gene revealed heterozygosity for a missense mutation (c.6907G>A) in affected subjects, resulting in a p.V2303M substitution in the aggrecan G3 domain C-type lectin. This domain is important for the interaction with other proteins in the cartilage extracellular matrix. To determine the effect of the V2303M substitution on secretion and interaction, we performed binding studies with recombinant mutated and wild type G3 proteins. We found decreased affinity or complete loss of interaction between V2303M aggrecan and fibulin1, fibulin2 and tenascin-R. Analysis of articular cartilage from an affected family member confirmed that V2303M aggrecan is produced and present. In search for gene mutations associated with multiple epiphyseal dysplasia (MED) we considered the ACAN-gene a likely candidate. The ACAN-gene was analysed in 39 individuals with MED and screened negative for mutations in six previously known MED genes. Sequence analysis revealed a heterozygous missense mutation (c.1448G>T) in one adult male and compound heterozygous missense mutations (c.1366T>C and c.836G>A) in a five year old boy with healthy parents, each of them carrier for one of the mutations. A large family segregating autosomal dominant brachymesophalangia and OCD in finger joints was characterised. The clinical presentation in six affected family members was consistent with the diagnosis Brachydactyly type A1, in this family characterized by shortening of the middle phalanges, short ulnar styloid process, flattening of the metacarpal heads and mild osteoarthritis. The condition may be caused by mutations in the Indian hedgehog gene (IHH) or a yet unidentified gene on chromosome 5p13. Sequence analysis of the IHH-gene in affected individuals revealed a novel C to T transition (c.472C>T) leading to a p.158Arg>Cys substitution. Residue 158 in IHH is highly conserved throughout evolution and molecular structure modelling of IHH suggests that the R158C substitution leads to a conformational change at the site of interaction with the IHH-receptor. This supports that the substitution causes Brachydactyly type A1 in this family. In summary, we report on the clinical, radiological and molecular genetic characteristics of the three skeletal disorders OCD, MED and BDA1. Our results provide a novel molecular mechanism in the pathophysiology of familial osteochondritis dissecans confirming the importance of aggrecan C-type lectin for cartilage function. We also show that ACAN-gene mutations may be associated with MED extending the spectrum of skeletal dysplasias associated with the aggrecan gene. Finally, we report on a novel missense mutation in a conserved region of the IHH-gene associated with BDA1.

The aim of this thesis is to investigate the effect of genetic mutations on the pathophysiology of two human disorders: Diamond-Blackfan Anemia (DBA) and isolated congenital nail dysplasia. The first part of this thesis (Paper I-III) investigates the mechanism associated with DBA. DBA is a rare bone marrow failure syndrome characterized by the absence or decrease of erythroid precursor cells. The disease is further associated with growth retardation, malformations, predisposition to malignant disease and heterozygous mutations in ribosomal protein (RP) genes. The second part of this thesis (Paper IV) investigates the genetic basis of isolated autosomal recessive nail dysplasia characterized by pachyonychia and onycholysis of both finger- and toenails. It further dissects the molecular mechanisms regulating nail development. In the first study, we investigated the previously reported RPS19/PIM-1 interaction by generating a combined Rps19/Pim-1 knockout mouse model. We found that allelic Rps19 insufficiency and Pim-1 deficiency have a cooperative effect on murine hematopoiesis resulting in increased myeloid cellularity associated with cell cycle alterations and reduced apoptosis. In the second study, we analyzed primary fibroblasts from DBA patients with truncating mutations in RPS19 or RPS24 and observed a marked delay in cellular growth associated with specific cell cycle defects. In the third study, we discovered that recombinant RPS19 binds its own mRNA and that the binding is altered when two DBA-associated RPS19 mutations are introduced. In the fourth study, we identified mutations in the WNT signaling receptor Frizzled 6 (FZD6). We observed that the nonsense mutant fails to interact with the first downstream effector Dishevelled. Fzd6 mutant mice displayed claw malformations and we detected a transient Fzd6 expression in the distal digits at the embryonic time point for nail development. In summary, this thesis elucidates several mechanisms in the etiology of DBA and congenital nail dysplasia and mechanisms regulating nail development.

No description available.

Bronchopulmonary dysplasia (BPD) is a chronic neonatal lung injury (CNLI) affecting infants of < 32 weeks gestation, which has a significant associated morbidity and mortality. The hallmarks of BPD as seen in the current era are arrested alveologenesis and parenchymal thickening. Those most severely affected may develop pulmonary hypertension which worsens the prognosis. No effective preventive therapy exists. Generation of damaging reactive oxygen species is implicated in its development. The more recently recognized reactive nitrogen species may also contribute to this disease. Thus, there is considerable interest in preventive antioxidant therapies, but results to date have not been promising. Newborn rats, exposed to 60% O2 for 14 days, develop a parenchymal injury and pulmonary hypertension that resembles the morphological features of human BPD. Previous studies have shown that following exposure to 60% O2, a pulmonary influx of neutrophils is followed by that of macrophages. Inhibiting the influx of neutrophils prevents the generation of reactive oxygen species, while simultaneously enhancing postnatal lung growth. Other interventions have shown that development of pulmonary hypertension is dependent upon increases in both 8-isoprostane and its downstream regulator of vascular tone, endothelin-1. Gentler ventilation strategies, incorporated to minimize induction of stretch-mediated pro-inflammatory cytokines, have shown benefits of permissive hypercapnia in adult lung injury. Multicentre clinical trials of permissive hypercapnia in neonates have not shown benefit. Therapeutic hypercapnia has been demonstrated to have a protective effect of PaCO2 in both acute studies of ventilator-induced and ischemia-reperfusion injuries in animal models. In the studies reported herein, therapeutic hypercapnia was found to completely protect against CNLI and attenuate 60% O2-induced macrophage-derived protein nitration. The likely nitrating agent was macrophage-derived peroxynitrite. The critical role of peroxynitrite, in the development of chronic neonatal lung injury in this model, was confirmed using a peroxynitrite decomposition catalyst. This protected against the impairments of alveolarization and of pulmonary vascularization induced by 60% O2. These results suggest a more significant role for reactive nitrogen species than previously recognized. Finally, preliminary evidence is presented supporting a role for neutrophil-derived elastase in initiating the macrophage influx in the lungs, required for peroxynitrite generation, during 60% O2-mediated injury.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Lung diseases associated with immaturity may contribute to the delay in the development of the newborn preterm. The oral feeding may suffer because they spend a lot of energy function in the disorder of the respiratory muscles and the lack of coordination between sucking / swallowing / breathing. The objective of this research was to compare the effects of increased technical expiratory flow slow in relation to the technical manual chest vibration on cardiorespiratory parameters and food performance of newborn preterm with lung disease. Babies who fulfilled the inclusion criteria and that those responsible have allowed their participation, were allocated at random to one of the groups (group 1 - increased expiratory flow slow; group 2 - manual chest vibration). We collected the cardiorespiratory parameters (RR, HR, SpO2) five minutes prior to physical therapy after 5 minutes started oral feeding, and 5 minutes after the end of the food supply. The physical therapy continued until obtaining the full orally, twice daily. Oral feeding performance was evaluated using the variables proficiency, throughput and performance oral feeding, the first oral feeding, and the days to reach full orally. The expiratory flow slow increase technique provided greater cardiorespiratory stability in children with respiratory distress syndrome and bronchopulmonary dysplasia in FR parameter (p=0.0029 and p=0.0344, respectively). In comparison within the group, for children with hyaline membrane disease subjected to vibration there was a significant increase in RR at the end of feeding (p=0.008). Submitted to the increase in technical expiratory flow slow the RF remained stable with significant increase in SpO2 (p=0.001).In the analysis of food performance, it was observed that physical therapy technique did not influence the variables proficiency, throughput and oral feeding performance in the first orally, and did not influence the dietary transition. We conclude that, although the technique of increased expiratory flow has not shown effects on oral feeding performance, presented benefits to newborn preterm, compared to vibration because it provided greater cardiorespiratory stability. / Doenças pulmonares associadas à imaturidade podem contribuir para o atraso no desenvolvimento do recém-nascido pré-termo. A alimentação via oral pode ser prejudicada, pois eles gastam muita energia em função da desordem da musculatura respiratória e a falta de coordenação entre sucção/deglutição/respiração. O objetivo dessa pesquisa foi comparar os efeitos da técnica de aumento do fluxo expiratório lento, em relação à técnica vibração manual torácica, sobre os parâmetros cardiorrespiratórios e a performance alimentar de recém-nascidos pré-termo com doença pulmonar. Os bebês que se enquadraram nos critérios de inclusão e que os responsáveis permitiram sua participação, foram alocados por sorteio para um dos grupos (grupo 1 aumento do fluxo expiratório lento; grupo 2 vibração manual torácica). Foram coletados os parâmetros cardiorrespiratórios (FR, FC, SatO2) 5 minutos antes da fisioterapia, após 5 minutos de iniciada alimentação via oral, e 5 minutos após término da oferta alimentar. O atendimento fisioterapêutico continuou até a obtenção da via oral plena, duas vezes ao dia. A performance alimentar oral foi avaliada através das variáveis proficiência, taxa de transferência e desempenho alimentar oral, na primeira mamada oral, e pelos dias para obtenção da via oral plena. A técnica de aumento do fluxo expiratório lento proporcionou maior estabilidade cardiorrespiratória nas crianças com doença da membrana hialina e displasia broncopulmonar no parâmetro de FR (p=0,0029 e p=0,0344, respectivamente). Na comparação dentro do próprio grupo, para as crianças com doença da membrana hialina submetidas à vibração houve aumento significativo da FR, ao final da mamada (p=0,008). Nas submetidas à técnica de aumento do fluxo expiratório lento a FR manteve-se estável com elevação significativa na SatO2 (p=0,001). Na análise da performance alimentar, observou-se que a técnica de fisioterapia não influenciou as variáveis proficiência, taxa de transferência e desempenho alimentar oral, na primeira via oral, assim como não influenciou a transição alimentar. Conclui-se que, embora a técnica de aumento do fluxo expiratório não tenha mostrado efeito sobre a performance alimentar oral, apresentou benefícios ao recém-nascido pré-termo, quando comparada à vibração, pois proporcionou maior estabilidade cardiorrespiratória.

Introdução: Há tempos Micoplasmas Genitais como o Ureaplasma vêm sendo implicados na patogênese de trabalho de parto prematuro e morbidade neonatal, mas seu real papel permanece obscuro e sua prevalência no sangue de recém-nascidos de muito baixo peso ainda não foi estudada em nosso meio. Objetivo: Determinar a prevalência da infecção por Ureaplasma urealyticum (Uu) e Ureaplasma parvum (Up) em uma amostra de recém-nascidos de muito baixo peso (RNMBP) e avaliar os fatores associados. Pacientes e métodos: Foi realizada extração de DNA de amostras de sangue de RNMBP coletadas nas primeiras 72 horas de vida e a presença de Uu e/ou Up foi identificada por técnica de Reação em Cadeia de Polimerase (PCR). Os recém-nascidos foram acompanhados até a alta hospitalar. Resultados: Noventa e cinco recém-nascidos de muito baixo peso foram incluídos no estudo. A detecção de Uu e/ou Up ocorreu em 12 recém-nascidos (12,63%). Em 5,26% foi detectado somente Uu, em 5,26% somente Up e em 2,11% ambos. Na análise univariada a presença de Ureaplasma foi associada à infecção ovular e a trabalho de parto prematuro. Pré-eclâmpsia e ser PIG foram associados a menor ocorrência de Ureaplasma. Quando analisados apenas os nascimentos decorrentes de trabalho de parto prematuro, a prevalência da infecção por Ureaplasma foi de 25%. Pela regressão logística passo a passo, somente trabalho de parto prematuro manteve-se estatisticamente significante aumentando em 9 vezes a chance de positividade para Ureaplasma. Conclusão: A infecção por Ureaplasma é comum em recém-nascidos de muito baixo peso, principalmente entre os nascidos de trabalho de parto prematuro, reforçando a hipótese de associação entre prematuridade e infecção por Ureaplasma. / Introduction: Ureaplasma has long been implicated in the pathogenesis of both preterm labor and neonatal morbidity, but its actual role remains unclear, and it’s prevalence in the blood of very low birth weight (VLBW) infants has not been studied in our country. Objective: To determine the prevalence of Ureaplasma urealyticum (Uu) and Ureaplasma parvum (Up) bacteremia in a sample of very low birth weight infants and evaluate the associated factors. Patients and methods: DNA was extracted from blood samples collected during the first 72 hours of life of VLBW infants and the presence of Uu and/or Up was identified by the technique of Polymerase Chain Reaction (PCR). The newborns were followed up until hospital discharge. Results: Ninety-five very low birth weight newborns were included in the study. Detection of Uu and / or Up occurred in 12 infants (12.6%). We detected Uu in 5.2%, Up in 5.2% and both in 2.1%. In univariate analysis the presence of Ureaplasma was associated with clinical chorioamnionitis and preterm labor. Pre-eclampsia and SGA were associated with lower incidence of Ureaplasma. When analyzing only the births due to preterm labor, the prevalence of Ureaplasma bacteremia was 25%. Only preterm labor remained statistically significant after step by step logistic regression analysis increasing by 9 times the chance of Ureaplasma occurrence. Conclusion: Ureaplasma bacteremia is common in very low birth weight infants, especially among those born of premature labor, reinforcing the hypothesis of an association between prematurity and Ureaplasma infection.

Cysteine rich with EGF-like domains 2 (Creld2) is a novel endoplasmic reticulum (ER) resident molecular chaperone that has been recently implicated in the ER stress signalling response (ERSS) and the unfolded protein response (UPR). Global transcriptomic data derived from in vivo mouse models of rare chondrodysplasias; Multiple Epiphyseal Dysplasia (MED Matn3 p.V194D) and Metaphyseal chondrodysplasia type Schmid (MCDS Col10a1 p.N617K), identified a significant upregulation in Creld2 expression in mutant chondrocytes. These chondrodysplasias share a common disease signature consisting of aberrant folding of a matrix component often as a result of inappropriate alignment of intramolecular disulphide bonds. This in turn culminates in toxic protein aggregation, intracellular retention mutant polypeptides and a classical ER stress response. The aim of this study was to further analyse the function of Creld2 in cartilage development and chondrodysplasias in which endochondral bone growth is perturbed. Protein disulphide isomerases (PDIAs) were amongst the most up-regulated genes in the MED and MCDS mouse models, consistent with the prolonged exposure of normally 'buried' cysteine residues. This led to the hypothesis that Creld2 was functioning as a novel PDI-like oxidoreductase to assist in the correct folding and maturation of aggregated misfolded polypeptide chains through REDOX regulated thiol disulphide exchange. A series of Creld2-CXXA substrate trapping mutants were generated in order to determine whether Creld2 possessed inherent isomerase activity. Here potential substrates interacting with Creld2 were 'trapped' as mixed disulphide intermediates, then isolated by immunoprecipitation and identified by mass spectrometry analysis. It was demonstrated that Creld2 possessed a catalytic active CXXC motif in its N-terminus that enabled the molecular chaperone to participate in REDOX regulated thiol disulphide exchange with at least 20 potential substrates including; laminin (alpha3,β3,γ2), thrombospondin 1, integrin alpha3 and type VI collagen. There was also numerous co-chaperones and foldases thought to be part of a specialised protein-protein interactome (PPI) for folding nascent polypeptides translocating the ER lumen. Moreover, co-immunoprecipitation experiments supported a protein-protein interaction between Creld2 and mutant matrilin-3, thereby inferring a potential chondro-protective role in resolving non-native disulphide bonded aggregates in MED. An established biochemical approach was employed to test the hypothesis that all MATN3-MED disease causing mutations have a generic cellular response to the β-sheet V194D mutation, consisting of intracellular retention, protein aggregation and ER stress induction. Several missense mutations were selected for analyses which encompassed a spectrum of disease severity and included examples of both β-sheet and alpha helical mutations. It was possible to define a reliable and reproducible assay for categorising MATN3 missense mutations into pathological or benign based on these basic parameters. This study was extended further to determine whether there were common pathological mechanisms behind MED and Bethlem myopathy (BM) caused by missense mutations in von Willebrand Factor A domain (vWF-A) containing proteins (matrilin-3 and type VI collagen respectively). We chose to compare and contrast the effects of an archetypal MATN3-MED causing mutation (R121W) with the equivalent COL6A2-BM causing mutation (R876H). These mutations compromised protein folding and maturation, resulting in the familiar disease profile of intracellular retention, protein aggregation and an ER stress response in an artificial overexpression system. However, the mutant C2 domain was efficiently targeted for degradation whilst mutant matrilin-3 vWF-A domain appeared to be resistant to these molecular processes.Molecular genetics was employed to study the role of Creld2 in vivo. Creld2-/- null mice (both global and conditional) were generated to directly examine the role of Creld2 in endochondral bone growth. Global knock-out mice were viable with no overt phenotype at birth. However, female Creld2-/- null mice showed a significant reduction in body weight and tibia bone length at 3 weeks of age. A cartilage specific knock-out was generated to determine whether these skeletal abnormalities were attributed to a systemic or a direct effect on cartilage development. [Creld2Flox/Flox Col2Cre (+)] demonstrated a severe chondrodysplasia with significantly reduced body weight and long bone growth compared to control littermates. Morphological and histochemical analysis of mutant growth plates revealed gross disorganisation of the chondrocyte columns with extensive regions of hypocellularity. These pathological features were confirmed to be the result of reduced chondrocyte proliferation and increased/spatially dysregulated apoptosis throughout all zones of differentiation. Taken together, these data provide evidence that Creld2 possesses isomerase activity and exhibits distinct substrate specificity. Furthermore, Creld2 has a fundamental role in post-natal cartilage development and chondrocyte differentiation in the growth plate.

A SMD primária hipocelular ocorre com uma frequência de 10-20% dos casos de SMD no adulto, no entanto, é o subtipo mais frequente na infância. O diagnóstico da SMD primária hipocelular é bastante difícil, pois devido à ausência de células na medula óssea esta pode ser confundida com a LMA hipocelular ou AA. O diagnóstico diferencial entre estas entidades hematológicas é de extrema importância devido a maior agressividade da LMA e a possibilidade de evolução da SMD para LMA. Além disso, SMD e AA são indicadas para o TCTH, entretanto, o regime de condicionamento pré-transplante é específico para cada doença. A combinação entre a análise morfológica, realizada através do mielograma e biópsia de medula óssea, e análise citogenética tem desempenhado um papel fundamental no reconhecimento da SMD primária hipocelular. Entretanto, estudos têm sido realizados para tentar melhorar o diagnóstico da doença levando em consideração as características biológicas da SMD como a presença de apoptose. Sendo assim, este estudo teve como objetivo caracterizar o padrão cromossômico da SMD primária hipocelular e correlacionar com aspectos celulares e clínicos. Foram analisados citogeneticamente 86 casos de SMD primária hipocelular, 74 AR, 10 com AREB e 2 com AREB-t. Dentre os pacientes com AR 50% apresentaram cariótipo anormal e todos os pacientes com AREB e AREB-t apresentaram cariótipo anormal. A alteração cromossômica mais frequente foi a del(17p), seguida de alterações envolvendo o cromossomo 7. Nossos resultados sugerem que o padrão cromossômico em SMD primária hipocelular é caracterizado principalmente por perdas parciais e completas de cromossomos (deleções e monossomias). A análise citogenética auxiliou no diagnóstico dos casos com suspeita de SMD primária hipocelular e foi uma importante ferramenta para a escolha do tratamento. O IPSS mostrou ser um bom sistema de escala prognostica para este grupo de pacientes. Alterações envolvendo o cromossomo 17 estiveram associados com o subtipo AR e características displásicas envolvendo o setor granulocítico, no entanto, a del(17p) também pôde ser observada no subtipo AREB. Para análise de apoptose foram utilizadas 42 amostras de pacientes com SMD, 23 com SMD hipocelular, 8 com SMD normocelular e 11 com SMD hipercelular. O índice de apoptose total nos casos de SMD primária hipocelular apresentou uma média de 9,5%, enquanto os pacientes com SMD primária normocelular e hipercelular apresentaram uma média de 12% e 14,1%, respectivamente. Pela análise de linhagens específicas as células já comprometidas com o programa de diferenciação celular parecem ser o principal alvo do programa de apoptose. Apesar dos pacientes com SMD primária hipocelular apresentarem índice de apoptose total mais elevado que os controles eles foram sempre inferiores aos apresentados pela SMD primária normocelular e hipercelular, com exceção dos eritroblastos que foram maiores nos casos de SMD primária hipocelular. O índice de apoptose total foi maior nos estágios iniciais da doença independentemente da celularidade da medula óssea. Os pacientes com del (11q) e del (17p) estiveram associados com a diminuição do índice de apoptose total. Nossos resultados sugerem que a hipocelularidade da medula óssea não é causada pelo processo de apoptose e sim provavelmente por algum defeito no programa de proliferação celular. / Hypocellular primary MDS occurs in a frequency of 10-20% of the adults MDS cases, however it is the most frequent subtype in childhood. Diagnosis of hypocellular primary MDS is very difficult, because the small number of cells in bone marrow and it can be confused with hypocellular AML or AA. The differential diagnosis between these hematologic entities is extremely important because of AML is more aggressive and the possibility of MDS evolve to AML. Besides, MDS and AA are indicated to HSCT, however, conditioning regimens before the transplantation is specific for each disease. The combination between morphologic analysis, carried out through mielogram and bone marrow biopsy, and cytogenetic analysis have been performed a fundamental role on the recognition of hypocellular primary MDS. However, studies have been carried out to try improving the MDS diagnosis considering the biological characteristics as the presence of apoptosis. Thus, the aim of this study was characterize the chromosomal pattern of hypocellular primary MDS and correlate with cellular and clinic aspects. It was analyzed 86 cases of hypocellular primary MDS, 74 RA, 10 RAEB and 2 RAEB-t. Patients with RA presented 50% of abnormal karyotype and all patients with RAEB presented abnormal karyotype as well as RAEB-t patients. The most frequent chromosomal alterations in this study was del(17p) followed by alterations involving chromosome 7. Our results suggest that chromosomal pattern in hypocellular primary MDS is characterized mainly by partial and complete loss of chromosomes (deletion and monosomy). The cytogenetic analysis aided in diagnosis of cases with suspicion of hypocellular primary MDS and it was an important tool for treatment choice. IPSS showed to be a good prognostic scoring system for this group of patients. Alterations involving chromosome 17 were associated with RA subtype and dysplastic characteristics involving granulocytic setor, however, we could see del(17p) in RAEB patients. For apoptosis analysis were used 42 samples of MDS patients, 23 with primary hypocellular MDS, 8 with primary normocelular MDS and 11 with primary hipercelular MDS. The total apoptosis index in cases of hypocellular primary MDS presented a average of 9,5%, whereas patients with primary normocelular MDS and primary hipercelular MDS presented an average of 12% and 14,1%, respectively. For the analysis of specific lineage cells already commited with cellular proliferation program appears to be the main target of apoptosis program. Despite of patients with primary hypocellular MDS presented total apoptosis index more raised than controls they were always lower than primary normocelular MDS and primary hipercelular MDS, except for eritroblasts that were higher in primary hypocellular. The total apoptosis index was higher in initial stage of the disease independently of the bone marrow cellularity. Patients with del(11q) and del(17p) were associated with decreasing of total apoptosis index. Our results suggest that the hypocellularity of bone marrow is not caused by apoptosis process, but probably by probably some defect in cellular proliferation program.