Spontaneous osteonecrosis of the jaws in the maxilla of mice on antiresorptive treatment: A novel ONJ mouse model

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

A osteonecrose associada ao uso de bisfosfonatos

Projeto de Pós-Graduação/Dissertação apresentado à Universidade Fernando Pessoa como parte dos requisitos para obtenção do grau de Mestre em Medicina Dentária

Patofisiologia de osteonecrose induzida por bisfosfonatos e inibidores de RANK-L

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Experimental development of bisphosphonate-related osteonecrosis of the jaws in rodents

Osteonecrosis of the jaw (ONJ) following the use of bisphosphonates has become of increased interest in the scientific community, due in particular to its as-yet-unsolved pathogenesis. An experimental model of ONJ was induced in normal male rats [alendronate (ALN); 1 mg/Kg/day; n = 10] and matched controls (saline solution; n = 10). After 60 days of drug treatment, all animals were subjected to extractions of the left first lower molars and were euthanized at 3 and 28 days postsurgery. The following analyses were performed: (i) descriptive and quantitative (scores) histological evaluation, (ii) stereometry of distal sockets and (iii) biochemical measurement of C-telopeptide cross-linked collagen type I (CTX) and bone-specific alkaline phosphatase (BALP). The results showed that 28 days postsurgery the animals treated with ALN had areas of exposed and necrotic bone, associated with significant infection, especially in the interalveolar septum area and crestal regions, compared with controls. The levels of CTX, BALP and bone volume, as well as the degrees of inflammation and vascularization, were significantly reduced in these animals. Therefore, analysis of the data presented suggests that ALN therapy is associated with the development of osteonecrosis in the jaws of rodents after tooth extraction. © 2012 International Journal of Experimental Pathology.

Patofisiologia de osteonecrose induzida por bisfosfonatos e inibidores de RANK-L

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Genetic diversity and population structure of Musa accessions in ex situ conservation

Abstract Background Banana cultivars are mostly derived from hybridization between wild diploid subspecies of Musa acuminata (A genome) and M. balbisiana (B genome), and they exhibit various levels of ploidy and genomic constitution. The Embrapa ex situ Musa collection contains over 220 accessions, of which only a few have been genetically characterized. Knowledge regarding the genetic relationships and diversity between modern cultivars and wild relatives would assist in conservation and breeding strategies. Our objectives were to determine the genomic constitution based on Internal Transcribed Spacer (ITS) regions polymorphism and the ploidy of all accessions by flow cytometry and to investigate the population structure of the collection using Simple Sequence Repeat (SSR) loci as co-dominant markers based on Structure software, not previously performed in Musa. Results From the 221 accessions analyzed by flow cytometry, the correct ploidy was confirmed or established for 212 (95.9%), whereas digestion of the ITS region confirmed the genomic constitution of 209 (94.6%). Neighbor-joining clustering analysis derived from SSR binary data allowed the detection of two major groups, essentially distinguished by the presence or absence of the B genome, while subgroups were formed according to the genomic composition and commercial classification. The co-dominant nature of SSR was explored to analyze the structure of the population based on a Bayesian approach, detecting 21 subpopulations. Most of the subpopulations were in agreement with the clustering analysis. Conclusions The data generated by flow cytometry, ITS and SSR supported the hypothesis about the occurrence of homeologue recombination between A and B genomes, leading to discrepancies in the number of sets or portions from each parental genome. These phenomenons have been largely disregarded in the evolution of banana, as the “single-step domestication” hypothesis had long predominated. These findings will have an impact in future breeding approaches. Structure analysis enabled the efficient detection of ancestry of recently developed tetraploid hybrids by breeding programs, and for some triploids. However, for the main commercial subgroups, Structure appeared to be less efficient to detect the ancestry in diploid groups, possibly due to sampling restrictions. The possibility of inferring the membership among accessions to correct the effects of genetic structure opens possibilities for its use in marker-assisted selection by association mapping.

Bisphosphonat-assoziierte Osteonekrose der Kiefer : In-vitro-Untersuchungen zur Pathologie und zu möglichen Therapieansätzen

Die Bisphosphonat-assoziierte Osteonekrose der Kiefer (BP-ONJ) stellt eine ernstzunehmende Nebenwirkung der Therapie mit stickstoffhaltigen Bisphosphonaten (N-BP) dar, deren Ätiologie bisher noch nicht vollständig geklärt ist. Da entzündliche Prozesse eine wichtige Rolle zu spielen scheinen, wurde der Einfluss verschiedener Bisphosphonate auf die Mechanismen der granulozytären Erregerabwehr untersucht. Die N-BP Ibandronat, Pamidronat und Zoledronat steigerten die Phagozytose und den oxidativen Burst signifikant. Die fMLP-stimulierte Chemotaxis wurde durch Ibandronat und Zoledronat signifikant reduziert. Das stickstofffreie Clodronat zeigte keinen Effekt auf die getesteten Abwehrmechanismen. Auf der Suche nach therapeutischen Optionen gegen die BP-ONJ wurden die Isoprenoide Farnesol, Geranylgeraniol, Eugenol, Menthol, Limonene und Squalene auf deren Fähigkeit untersucht, die schädigenden Effekte Zoledronats auf verschiedene Zelllinien zu antagonisieren. Geranylgeraniol zeigte als einzige Verbindung eine protektive Wirkung auf gingivale Fibroblasten, Endothelzellen und Osteoblasten. Desweiteren kam es unter Zoledronat zum Anstieg der kleinen GTPasen RhoA und RhoB in gingivalen Fibroblasten. Auch der Gehalt an GTP-gebundenem RhoA stieg nach Zoledronat-Inkubation. Der Einfluss des N-BPs ließ sich auch auf Proteinebene durch Geranylgeraniol antagonisieren und nicht durch Farnesol. Die Tatsache, dass N-BP die granulozytäre Abwehr beeinflussen, unterstützt die Bedeutung keimreduzierender Maßnahmen im Rahmen der Nekroseprophylaxe und -therapie. Außerdem untermauern die Ergebnisse der Arbeit das Potential Geranylgeraniols als neue therapeutische Option.

Frequencies and risk factors for bisphosphonate-related osteonecrosis of the jaw in cancer patients: A matched case-control study

Bisphosphonates represent a unique class of drugs that effectively treat and prevent a variety of bone-related disorders including metastatic bone disease and osteoporosis. High tolerance and high efficacy rates quickly ranked bisphosphonates as the standard of care for bone-related diseases. However, in the early 2000s, case reports began to surface that linked bisphosphonates with osteonecrosis of the jaw (ONJ). Since that time, studies conducted have corroborated the linkage. However, as with most disease states, many factors can contribute to the onset of disease. The aim of this study was to determine which comorbid factors presented an increased risk for developing ONJ in cancer patients.^ Using a case-control study design, investigators used a combination of ICD-9 codes and chart review to identify confirmed cases of ONJ at The University of Texas M. D. Anderson Cancer Center (MDACC). Each case was then matched to five controls based on age, gender, race/ethnicity, and primary cancer diagnosis. Data querying and chart review provided information on variables of interest. These variables included bisphosphonate exposure, glucocorticoids exposure, smoking history, obesity, and diabetes. Statistical analysis was conducted using PASW (Predictive Analytics Software) Statistics, Version 18 (SPSS Inc., Chicago, Illinois).^ One hundred twelve (112) cases were identified as confirmed cases of ONJ. Variables were run using univariate logistic regression to determine significance (p < .05); significant variables were included in the final conditional logistic regression model. Concurrent use of bisphosphonates and glucocorticoids (OR, 18.60; CI, 8.85 to 39.12; p < .001), current smokers (OR, 2.52; CI, 1.21 to 5.25; p = .014), and presence of diabetes (OR, 1.84; CI, 1.06 to 3.20; p = .030) were found to increase the risk for developing ONJ. Obesity was not associated significantly with ONJ development.^ In this study, cancer patients that received bisphosphonates as part of their therapeutic regimen were found to have an 18-fold increase in their risk of developing ONJ. Other factors included smoking and diabetes. More studies examining the concurrent use of glucocorticoids and bisphosphonates may be able to strengthen any correlations.^

Osteonecrose dos maxilares associada a fármacos anti-reabsorção óssea

Os fármacos anti-reabsorção óssea mais utilizados atualmente são os bifosfonatos que são medicamentos que inibem a actividade osteoclástica. O mecanismo de ação destes fármacos consiste na redução da reabsorção óssea pois inibem a apoptose dos osteoclastos e promovem a inibição da angiogénese. Estes fármacos são utilizados no tratamento de doenças como a osteoporose, hipercalcemia, doença de Paget e em pacientes oncológicos com metástases ósseas de tumores sólidos e mieloma múltiplo. Por outro lado, estes fármacos além de todos os benefícios que têm para os pacientes nestas condições, podem ter como complicação a osteonecrose dos maxilares (ONM). A ONM é uma complicação oral grave caracterizada, na maioria, por uma osteomielite inicial que normalmente evolui para uma exposição de osso necrosado acompanhada por dor na maxila ou na mandíbula. Nos doentes oncológicos têm sido diagnosticados vários casos de necrose óssea mais frequentemente na mandíbula. Esta patologia (ONM) apesar de ter baixa incidência e do seu aparecimento ser relativamente recente, levou à introdução de algumas recomendações internacionais para o uso de bifosfonatos, principalmente em pacientes oncológicos. Para a execução deste trabalho recorri a fontes de pesquisas como as bases de dados como a PubMed, B-On e, também ao Repositório Institucional da Universidade Fernando Pessoa das quais resultaram 198 artigos e duas monografias realizadas por exalunos da Universidade Fernando Pessoa. Com a realização deste trabalho foi possível esclarecer algumas dúvidas acerca dos efeitos que os fármacos anti-reabsorção óssea têm no organismo e mais especificamente na cavidade oral, de forma a estar consciente dos riscos que estes pacientes correm, caso lhes sejam realizados procedimentos como é o caso, das exodontias ou da colocação de implantes.