Effects of estrogen on growth plate senescence and epiphyseal fusion

Estrogen is critical for epiphyseal fusion in both young men and women. In this study, we explored the cellular mechanisms by which estrogen causes this phenomenon. Juvenile ovariectomized female rabbits received either 70 μg/kg estradiol cypionate or vehicle i.m. once a week. Growth plates from the proximal tibia, distal tibia, and distal femur were analyzed after 2, 4, 6, or 8 weeks of treatment. In vehicle-treated animals, there was a gradual senescent decline in tibial growth rate, rate of chondrocyte proliferation, growth plate height, number of proliferative chondrocytes, number of hypertrophic chondrocytes, size of terminal hypertrophic chondrocytes, and column density. Estrogen treatment accelerated the senescent decline in all of these parameters. In senescent growth plates, epiphyseal fusion was observed to be an abrupt event in which all remaining chondrocytes were rapidly replaced by bone elements. Fusion occurred when the rate of chondrocyte proliferation approached zero. Estrogen caused this proliferative exhaustion and fusion to occur earlier. Our data suggest that (i) epiphyseal fusion is triggered when the proliferative potential of growth plate chondrocytes is exhausted; and (ii) estrogen does not induce growth plate ossification directly; instead, estrogen accelerates the programmed senescence of the growth plate, thus causing earlier proliferative exhaustion and consequently earlier fusion.

Targeted overexpression of parathyroid hormone-related peptide in chondrocytes causes chondrodysplasia and delayed endochondral bone formation.

Parathyroid hormone-related peptide (PTHrP) was initially identified as a product of malignant tumors that mediates paraneoplastic hypercalcemia. It is now known that the parathyroid hormone (PTH) and PTHrP genes are evolutionarily related and that the products of these two genes share a common receptor, the PTH/PTHrP receptor. PTHrP and the PTH/PTHrP receptor are widely expressed in both adult and fetal tissues, and recent gene-targeting and disruption experiments have implicated PTHrP as a developmental regulatory molecule. Apparent PTHrP functions include the regulation of endochondral bone development, of hair follicle formation, and of branching morphogenesis in the breast. Herein, we report that overexpression of PTHrP in chondrocytes using the mouse type II collagen promoter induces a novel form of chondrodysplasia characterized by short-limbed dwarfism and a delay in endochondral ossification. This features a delay in chondrocyte differentiation and in bone collar formation and is sufficiently marked that the mice are born with a cartilaginous endochondral skeleton. In addition to the delay, chondrocytes in the transgenic mice initially become hypertrophic at the periphery of the developing long bones rather than in the middle, leading to a seeming reversal in the pattern of chondrocyte differentiation and ossification. By 7 weeks, the delays in chondrocyte differentiation and ossification have largely corrected, leaving foreshortened and misshapen but histologically near-normal bones. These findings confirm a role for PTHrP as an inhibitor of the program of chondrocyte differentiation. PTHrP may function in this regard to maintain the stepwise differentiation of chondrocytes that initiates endochondral ossification in the midsection of endochondral bones early in development and that also permits linear growth at the growth plate later in development.

Complexação de guaiacol com ß-ciclodextrina para tratamento de alveolite seca: avaliação in vitro e in vivo

A alveolite seca (AS) é uma das complicações pós-operatórias mais comuns e sintomáticas na odontologia, porém, até o momento não há um protocolo de tratamento definido. O composto fenólico guaiacol (Gu) é um dos materiais utilizados para revestimento intra-alveolar devido às suas propriedades analgésicas, antioxidantes e antimicrobianas. Contudo, sua desvantagem é a dificuldade de manipulação decorrente da sua baixa estabilidade, alta volatilidade e sensibilidade à oxidação. Para melhorar suas propriedades e aumentar sua aplicabilidade clínica, um complexo de inclusão de Gu com ß-ciclodextrina (ßcd) foi desenvolvido. A formação do complexo supramolecular de Gu:ßcd foi caracterizada mediante a ressonância magnética nuclear (RMN), nos experimentos de 1H e 2D ROESY. A atividade antibacteriana do Gu e Gu:ßcd frente a Escherichia coli, Staphylococcus aureus, Streptococcus mitis, Streptococcus mutans, Streptococcus sanguis e Aggregatibacter actinomycetemcomitans foi analisada pelo método da microdiluição e sua citotoxicidade em osteoblastos de calvária de rato, foi estudado com o ensaio do MTT. O processo de reparo alveolar induzido pelo Gu:ßcd foi avaliado histologicamente após tratamento de alveolite seca em molares inferiores de ratos. A RMN mostrou correlações espaciais entre os hidrogênios internos (H3 e H5) da ßcd e os hidrogênios aromáticos, H(a) e H(b) do Gu, confirmando a formação do complexo. A complexação do Gu na ßcd potencializou seu efeito antibacteriano e reduziu sua citotoxicidade em osteoblastos. O estudo in vivo evidenciou a ocorrência de ossificação no ápice alveolar dos ratos tratados com Gu:ßcd, no 7o dia. No 14o dia, as trabéculas ósseas ocuparam também o terço médio do alvéolo e no 21o dia, todo o alvéolo se encontrava preenchido por osso neoformado. Estes resultados foram similares ao controle negativo e superiores ao controle positivo (Alvogyl®). Os benefícios obtidos pela inclusão do Gu na ßcd foram demonstrados pela melhora das propriedades biológicas do Gu in vitro e o adequado reparo alveolar in vivo.

Questions in Narratives from Oral Tradition to Literature

Thesis (Ph.D.)--University of Washington, 2016-06

Choroidal osteoma: evidence of progression and decalcification over 20 years

Choroidal osteoma is a rare, benign, ossifying tumour of the choroid of unknown aetiology. In contrast to other types of intraocular ossification, choroidal osteoma is found typically in young healthy females in the second or third decades of life with no history of systemic or ocular disease. Choroidal osteoma is a deep, pale yellow lesion with distinct geographic borders at the juxtapapillary or macular region, with branching 'spider' vessels on the surface of the tumour. These features should help differentiate choroidal osteoma from other types of intraocular tumour and the diagnosis can be confirmed with ultrasonography and computerised tomography. Here we report an initially unilateral case of choroidal osteoma, which decalcified over 20 years but during the same period the fellow eye also developed a choroidal osteoma to become a bilateral case. Despite the benign nature of the tumour, vision may be compromised by gradual atrophy of the overlying retina, serous retinal detachment, accumulation of sub-retinal fluid and sub-retinal haemorrhage associated with choroidal neovascularisation. Frequent examinations are recommended for patients with choroidal osteoma, for early detection of a subretinal neovascular membrane and potential treatment with laser photocoagulation.

Apoptosis of neurons and oligodendrocytes in the spinal cord of spinal hyperostotic mouse (twy/twy):possible pathomechanism of human cervical compressive myelopathy

Cervical compressive myelopathy is the most serious complication of cervical spondylosis or ossification of the posterior longitudinal ligament (OPLL) and the most frequent cause of spinal cord dysfunction. There is little information on the exact pathophysiological mechanism responsible for the progressive loss of neural tissue in the spinal cord of such patients. In this study, we used the spinal hyperostotic mouse (twy/twy) as a suitable model of human spondylosis, and OPLL to investigate the cellular and molecular changes in the spinal cord. Mutant twy/twy mouse developed ossification of the ligamentum flavum at C2-C3 and exhibited progressive paralysis.

The prevalence and phenotype of activated microglia/macrophages within the spinal cord of the hyperostotic mouse (twy/twy) changes in response to chronic progressive spinalcord compression:implications for human cervical compressive myelopathy

Background:Cervical compressive myelopathy, e.g. due to spondylosis or ossification of the posterior longitudinal ligament is a common cause of spinal cord dysfunction. Although human pathological studies have reported neuronal loss and demyelination in the chronically compressed spinal cord, little is known about the mechanisms involved. In particular, the neuroinflammatory processes that are thought to underlie the condition are poorly understood. The present study assessed the localized prevalence of activated M1 and M2 microglia/macrophages in twy/twy mice that develop spontaneous cervical spinal cord compression, as a model of human disease.Methods:Inflammatory cells and cytokines were assessed in compressed lesions of the spinal cords in 12-, 18- and 24-weeks old twy/twy mice by immunohistochemical, immunoblot and flow cytometric analysis. Computed tomography and standard histology confirmed a progressive spinal cord compression through the spontaneously development of an impinging calcified mass.Results:The prevalence of CD11b-positive cells, in the compressed spinal cord increased over time with a concurrent decrease in neurons. The CD11b-positive cell population was initially formed of arginase-1- and CD206-positive M2 microglia/macrophages, which later shifted towards iNOS- and CD16/32-positive M1 microglia/macrophages. There was a transient increase in levels of T helper 2 (Th2) cytokines at 18 weeks, whereas levels of Th1 cytokines as well as brain-derived neurotrophic factor (BDNF), nerve growth factor (NGF) and macrophage antigen (Mac) -2 progressively increased.Conclusions:Spinal cord compression was associated with a temporal M2 microglia/macrophage response, which may act as a possible repair or neuroprotective mechanism. However, the persistence of the neural insult also associated with persistent expression of Th1 cytokines and increased prevalence of activated M1 microglia/macrophages, which may lead to neuronal loss and demyelination despite the presence of neurotrophic factors. This understanding of the aetiopathology of chronic spinal cord compression is of importance in the development of new treatment targets in human disease. © 2013 Hirai et al.

Characterization of a Novel Mouse Phenotype with Marked Hydrocephalus

In multigenic diseases, disorders where mutations in multiple genes affect the expressivity of the disease, genetic interactions play a major role in prevalence and phenotypic severity. While studying the genetic interactions between Pax3 and EdnrB in the melanocyte lineage, a new phenotype was noted in 80% of Pax3 mutants that we believe to be a novel murine model for hydrocephalus. Hydrocephalus, an accumulation of cerebrospinal fluid in the cranial cavity due to obstruction of flow in and out of the cavity, is one of the most common birth defects surpassing Down syndrome. Characteristic to hydrocephalus is a "domed" head appearance, expansion of the ventricles of the brain, and loss of neurons with hyperproliferation of glial cell types all three of which were seen in the mutant mice. The phenotype also consisted of craniofacial deformities coupled with skeletal defects including, but not limited to kyphosis, lordosis, and an apparent shortening of the some limbs. For the cellular analysis of the hydrocephalus phenotype, brains were removed and stained with two antibodies: Glial Fibrillary Acidic Protein (GFAP) and Neurofilament (NF), which are astrocyte- and neuron- specific respectively. A higher number of cells expressing GF AP and a lower number of cells expressing NF were seen in the mutant brain, when compared to control. For skeletal deformity analysis, affected mice skeletons were stained with Alizarin Red and Alcian Blue showing no apparent difference in ossification. Future genetic analysis of these mutant mice has the potential to identify novel gene modifiers involved in the promotion of this particular phenotype.

Angiogenesis in the pathogenesis of inflammatory joint and lung diseases

This paper reviews hypotheses about roles of angiogenesis in the pathogenesis of inflammatory disease in two organs, the synovial joint and the lung. Neovascularisation is a fundamental process for growth and tissue repair after injury. Nevertheless, it may contribute to a variety of chronic inflammatory diseases, including rheumatoid arthritis, osteoarthritis, asthma, and pulmonary fibrosis. Inflammation can promote angiogenesis, and new vessels may enhance tissue inflammation. Angiogenesis in inflammatory disease may also contribute to tissue growth, disordered tissue perfusion, abnormal ossification, and enhanced responses to normal or pathological stimuli. Angiogenesis inhibitors may reduce inflammation and may also help to restore appropriate tissue structure and function

Low-dose histone deacetylase inhibitor treatment leads to tumor growth arrest and multi-lineage differentiation of malignant rhabdoid tumors

PURPOSE: Malignant rhabdoid tumor (MRT) and atypical teratoid rhabdoid tumors (ATRT) are rare aggressive undifferentiated tumors primarily affecting the kidney and CNS of infants and young children. MRT are almost exclusively characterized by homozygous deletion or inactivation of the chromatin remodeling gene SMARCB1 SMARCB1 protein loss leads to direct impairment of chromatin remodeling and we have previously reported a role for this protein in histone acetylation. This provided the rationale for investigating the therapeutic potential of histone deactylase inhibitors (HDACi) in MRT. EXPERIMENTAL DESIGN: Whereas previously HDACis have been used at doses and schedules that induce cytotoxicity, in the current studies we have tested the hypothesis, both in vitro and in vivo, that sustained treatment of human MRT with low-dose HDACi can lead to sustained cell growth arrest and differentiation. RESULTS: Sustained low-dose panobinostat (LBH589) treatment led to changes in cellular morphology associated with a marked increase in the induction of neural, renal, and osteoblast differentiation pathways. Genome-wide transcriptional profiling highlighted differential gene expression supporting multilineage differentiation. Using mouse xenograft models, sustained low-dose LBH589 treatment caused tumor growth arrest associated with tumor calcification detectable by X-ray imaging. Histological analysis of LBH589-treated tumors revealed significant regions of ossification, confirmed by Alizarin Red staining. Immunohistochemical analysis showed increased TUJ1 and PAX2 staining suggestive of neuronal and renal differentiation, respectively. CONCLUSIONS: Low-dose HDACi treatment can terminally differentiate MRT tumor cells and reduce their ability to self-renew. The use of low-dose HDACi as a novel therapeutic approach warrants further investigation.

An Artificial Intelligence Approach to Individuals' Age Assessment

A link between patterns of pelvic growth and human life history is supported by the finding that, cross-culturally, variation in maturation rates of female pelvis are correlated with variation in ages of menarche and first reproduction, i.e., it is well known that the human dimensions of the pelvic bones depend on the gender and vary with the age. Indeed, one feature in which humans appear to be unique is the prolonged growth of the pelvis after the age of sexual maturity. Both the total superoinferior length and mediolateral breadth of the pelvis continues to grow markedly after puberty, and do not reach adult proportions until the late teens years. This continuation of growth is accomplished by relatively late fusion of the separate centers of ossification that form the bones of the pelvis. Hence, in this work we will focus on the development of an intelligent decision support system to predict individual’s age based on a pelvis' dimensions criteria. Some basic image processing techniques were applied in order to extract the relevant features from pelvic X-rays, being the computational framework built on top of a Logic Programming approach to Knowledge Representation and Reasoning that caters for the handling of incomplete, unknown, or even self-contradictory information, complemented with a Case Base approach to computing.