TOMAZ PUGA LEIVAS

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5
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Instituto do Coração, Hospital das Clínicas, Faculdade de Medicina
Instituto de Ortopedia e Traumatologia, Hospital das Clínicas, Faculdade de Medicina
LIM/41 - Laboratório de Investigação Médica do Sistema Músculoesquelético, Hospital das Clínicas, Faculdade de Medicina

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  • article 7 Citação(ões) na Scopus
    Measurement of the concentration and size of aerosol particles and identification of the sources in orthopedic surgeries
    (2012) PEREIRA, Marcelo Luiz; VILAIN, Rogerio; LEIVAS, Tomaz Puga; TRIBESS, Arlindo
    In this study, the measurement of the concentration and size of particles and the identification of their sources were carried out at five orthopedic surgeries. The aerosol concentration and particle size distribution, ranging from 0.3 mu m 10 mu m, were measured and related to the type of indoor activity. The handling of surgical linen and gowns, handling of the patient, use of electrosurgical apparatus, use of a bone saw, handling of equipment, and cleaning of the room were identified as the most important sources of particles, with each of these activities posing different risks to the health of the patients and workers. The results showed that most of the particles were above 0.5 mu m and that there was a strong correlation among all particles of sizes above 1 mu m. Particles with diameters in the range of 0.3 mu m-0.5 mu m had a good correlation only with particles in the ranges of 0.5 mu m-1.0 mu m and 1.0 mu m-3.0 mu m in three of the surgeries analyzed. Findings led to the conclusion that most of the events responsible for generating aerosol particles in an orthopedic surgery room are brief, intermittent, and highly variable, thus requiring the use of specific instrumentation for their continuous identification and characterization.
  • article 13 Citação(ões) na Scopus
    Axial compressive strength of human vertebrae trabecular bones classified as normal, osteopenic and osteoporotic by quantitative ultrasonometry of calcaneus
    (2017) CESAR, R.; LEIVAS, T. P.; PEREIRA, C. A. M.; BOFFA, R. S.; GUARNIERO, R.; REIFF, R. B. D. M.; NETTO, A. M.; FORTULAN, C. A.; ROLLO, J. M. D. A.
    Introduction: Biomechanical assessment of trabecular bone microarchitecture contributes to the evaluation of fractures risk associated with osteoporosis and plays a crucial role in planning preventive strategies. One of the most widely clinical technics used for osteoporosis diagnosis by health professionals is bone dual-energy X-ray absorptiometry (DEXA). However, doubts about its accuracy motivate the introduction of congruent technical analysis such as calcaneal ultrasonometry (Quantitative Ultrasonometry - QUS). Methods: Correlations between Bone Quality Index (BQI), determined by calcaneal ultrasonometry of thirty (30) individuals classified as normal, osteopenic and osteoporotic, and elastic modulus (E) and ultimate compressive strength (UCS) from axial compression tests of ninety (90) proof bodies from human vertebrae trabecular bone, which were extracted from cadavers in the twelfth thoracic region (T12), first and fourth lumbar (L1 and L4). Results: Analysis of variance (ANOVA) showed significant differences for E (p = 0.001), for UCS (p = 0.0001) and BQI. Spearman’s rank correlation coefficient (rho) between BQI and E (r = 0.499) and BQI and UCS (r = 0.508) were moderate. Discussion: Calcaneal ultrasonometry technique allowed a moderate estimate of bone mechanical strength and fracture risk associated with osteoporosis in human vertebrae. © 2017, Brazilian Society of Biomedical Engineering. All rights reserved.
  • bookPart 0 Citação(ões) na Scopus
    Bone Quality Assessment at the Atomic Scale
    (2020) ROLLO, J. M. D. A.; BOFFA, R. S.; CESAR, R.; ERBERELI, R.; SCHWAB, D. C.; LEIVAS, T. P.
    The assessment of osteoporosis regarding bone mass and microarchitecture “quality” contributes in determining fracture risk. Therefore, the crystalline structure of hydroxyapatite may indicate the quality of trabecular bones through the identification of crystallite sizes, microhardness and microdeformation values and calcium and phosphorous proportions in the three types of bones: normal, osteopenic, and osteoporotic. Nine L1 vertebrae-dried trabecular bones from human cadavers were used. The characterization of the three types of bones was made through scanning electron microscopy, EDS, microhardness, and X-ray diffractometry with the Rietveld refinement method. The results show that the microstructural characterization possibilities the identification of the three types of bones: normal, osteopenic, and osteoporotic, allowing the detection of osteoporosis based on bone quality. © Springer Nature Switzerland AG 2020.