RESUMO
OBJECTIVES: Daily activities involve biomechanical strains acting on skeletal structures. This study identifies differences in activity patterns between males and females, and between young, middle, and older aged individuals within an excavated Muisca skeletal sample from the Eastern Andes region of Northern South America. MATERIALS AND METHODS: The Tibanica archaeological site (AD 1000-1400) is located at 2600 masl on the Sabana de Bogotá, Colombia. Cross-sectional geometric analysis of femurs from 63 individuals and paired-humerii from 33 individuals was used to examine bone size (TA), strength (J) and diaphyseal shape (Imax /Imin , Ix /Iy ). RESULTS: The findings indicate both age- and sex-related differences in activity patterns. An emphasis on upper body strength and robusticity was observed in the females, while males performed more strenuous work using their lower bodies, suggesting gender-based differences in labor. Men showed significant asymmetry in their humerii, with most showing right-hand dominance for upper body activities, while females showed high levels of humeral symmetry indicating similar levels of biomechanical stress for both arms. Female femoral diaphyseal shape changes with age, suggesting more mobility in youth and decreased mobility in middle and older ages. DISCUSSION: These results suggest that daily life may have been structured through patterns of routine labor that united and divided particular age and sex groups. Cross-sectional geometry data indicate women likely spent significant time and energy preparing food, especially grinding maize or other foods, while men may have done more long-distance walking potentially to work in agricultural fields or procure other resources.
Assuntos
Fenômenos Biomecânicos/fisiologia , Diáfises/anatomia & histologia , Fêmur/anatomia & histologia , Úmero/anatomia & histologia , Indígenas Sul-Americanos/história , Adolescente , Adulto , Anatomia Transversal , Antropologia Física , Colômbia , Diáfises/fisiologia , Feminino , Fêmur/fisiologia , História Medieval , Humanos , Úmero/fisiologia , Masculino , Pessoa de Meia-Idade , Fatores Sexuais , Adulto JovemRESUMO
Some pharmacologic effects on bone modeling may not be evident in studies of remodeling skeletons. This study analyzes some effects of olpadronate on cortical bone modeling and post-yield properties in femurs diaphyses (virtually only-modeling bones) of young rats by mid-diaphyseal pQCT scans and bending tests. We studied 20/22 male/female animals traetad orally with olpadronate (45-90 mg/kg/d, 3 months) and 8/9 untreated controls. Both OPD doses enhanced diaphyseal cross-sectional moments of inertia (CSMI) with no change in cortical vBMD and elastic modulus. Yield stiffness and strength were mildly increased. Post-yield strength, deflection and energy absorption were strikingly enhanced. Ultimate strength was enhanced mainly because of effects on bone mass/geometry and post-yield properties. The large improvement of post-yield properties could be explained by improvements in bone geometry. Improvements in bone mass/geometry over weight-bearing needs suggest an enhanced modeling-related response to mechanical stimuli. Effects on tissue microstructural factors (not measured) could not be excluded. Results reveal novel olpadronate effects on bone strength and toughness unrelated to tissue mineralization and stiffness, even at high doses. Further studies could establish whether this could also occur in modeling-remodeling skeletons. If so, they could counteract the negative impact of anti-remodeling effects of bisphosphonates on bone strength.
Assuntos
Conservadores da Densidade Óssea/farmacologia , Remodelação Óssea/efeitos dos fármacos , Calcificação Fisiológica/efeitos dos fármacos , Difosfonatos/farmacologia , Análise de Variância , Animais , Fenômenos Biomecânicos , Densidade Óssea/efeitos dos fármacos , Diáfises/anatomia & histologia , Diáfises/fisiologia , Relação Dose-Resposta a Droga , Módulo de Elasticidade , Elasticidade , Feminino , Fêmur/anatomia & histologia , Fêmur/fisiologia , Masculino , Ratos , Ratos Wistar , Caracteres Sexuais , Software , TomografiaRESUMO
An ultrasonometric and computed-tomographic study of bone healing was undertaken using a model of a transverse mid-shaft osteotomy of sheep tibiae fixed with a semi-flexible external fixator. Fourteen sheep were operated and divided into two groups of seven according to osteotomy type, either regular or by segmental resection. The animals were killed on the 90th postoperative day and the tibiae resected for the in vitro direct contact transverse and axial measurement of ultrasound propagation velocity (UV) followed by quantitative computer-aided tomography (callus density and volume) through the osteotomy site. The intact left tibiae were used for control, being examined in a symmetrical diaphyseal segment. Regular osteotomies healed with a smaller and more mature callus than resection osteotomies. Axial UV was consistently and significantly higher (p ≤ 0.01) than transverse UV and both transverse and axial UV were significantly higher for the regular than for the segmental resection osteotomy. Transverse UV did not differ significantly between the intact and operated tibiae (p=0.20 for regular osteotomy; p=0.02 for resection osteotomy), but axial UV was significantly higher for the intact tibiae. Tomographic callus density was significantly higher for the regular than for the resection osteotomy and higher than both for the intact tibiae, presenting a strong positive correlation with UV. Callus volume presented an opposite behavior, with a negative correlation with UV. We conclude that UV is at least as precise as quantitative tomography for providing information about the healing state of both regular and resection osteotomy.
Assuntos
Consolidação da Fratura/fisiologia , Fraturas da Tíbia/diagnóstico por imagem , Tomografia Computadorizada por Raios X/métodos , Ultrassonografia/métodos , Animais , Diáfises/diagnóstico por imagem , Diáfises/fisiologia , Modelos Animais de Doenças , Modelos Biológicos , Osteotomia , Ovinos , Tíbia/diagnóstico por imagem , Tíbia/fisiologia , Fraturas da Tíbia/fisiopatologiaRESUMO
The objective of this experiment was to determine the normal values of bone radiographic density (BRD) by using the optical densitometry in radiographic images and the biochemical values represented by serum calcium, ash percentage, and minerals (calcium, phosphorus, and magnesium) from tibia ash of Cobb broilers at 8, 22, and 43 d of age. A total of 14 broilers were used for densitometric analysis, and 15 were used for biochemical dosages. The BRD values increased (P < 0.05) with age and in all tibia regions (proximal epiphysis, diaphysis, and distal epiphysis), concluding that growth was a determinative factor for bone performance, demanding a higher BRD during broiler development. Tibia proximal epiphysis presented higher BRD values in relation to the other bone regions (P < 0.05), as a result of a possible biomechanical adaptation to ligaments and tension of the muscle tendons at this region, allowing the support of the muscle mass increase. The serum calcium values were kept constant, as a result of the appropriate nutritional levels of the diet that supported the animal homeostasis. The bone ash and mineral percentage increased (P < 0.05) at 22 d of age, due to the higher mineral requirement in this age. The correlation between bone densitometry and the invasive techniques showed that the bone densitometry can substitute the determination of mineral percentage in the ash. This experiment presented normal values of the noninvasive and invasive methods more used in aviculture, allowing us to compare, subsequently, pathological and physiological values or results of broilers fed with different diets.
Assuntos
Densidade Óssea/fisiologia , Galinhas/crescimento & desenvolvimento , Tíbia/crescimento & desenvolvimento , Envelhecimento , Animais , Diáfises/fisiologia , Epífises/fisiologiaRESUMO
The bone changes in hypothyroidism are characterized by a low bone turnover with a reduced osteoid apposition and bone mineralization rate, and a decreased osteoclastic resorption in cortical bone. These changes could affect the mechanical performance of bone. The evaluation of such changes was the object of the present investigation. Hypothyroidism was induced in female rats aged 21 days through administration of propylthiouracil in the drinking water for 70 days (HT group). Controls were untreated rats (C group). Right femur mechanical properties were tested in 3-point bending. Structural (load bearing capacity and stiffness), geometric (cross-sectional area and moment of inertia) and material (modulus of elasticity) properties were evaluated. The left femur was ashed for calcium content determination. Plasma T(4) concentration was significantly decreased in HT rats. Body and femur weight and length in HT rats were also reduced. Femoral calcium concentration in ash was higher in HT than in C rats. However, the femoral calcium mass was significantly lower in HT than in C rats because of the reduced femoral size seen in the former. The stiffness of bone material was higher in HT than in C rats, while the bone geometric properties were significantly lower. The "load capacity" was between 30 and 50% reduced in the HT group, although, the differences disappeared when the values were normalized per 100-g body weight. The lowered biomechanical ability observed in the femoral shafts of HT rats seems to be the expression of a diminished rate of growth. Qualitative alterations in the intrinsic mechanical properties of bone tissue were observed in HT rats, probably because the mineral content and the modulus of elasticity were positively affected. The cortical bone of the HT rat thus appears as a bone with a higher than normal strength and stiffness relative to body weight, probably due to improvement of bone material quality due to an increased matrix calcification.
Assuntos
Diáfises/fisiologia , Fêmur/fisiologia , Hipotireoidismo/fisiopatologia , Animais , Fenômenos Biomecânicos , Osso e Ossos/fisiologia , Diáfises/crescimento & desenvolvimento , Feminino , Fêmur/crescimento & desenvolvimento , Testes de Dureza , Tamanho do Órgão , Ratos , Ratos Sprague-Dawley , Estresse Mecânico , Suporte de CargaRESUMO
Periosteal regeneration was investigated in two periosteal donor sites of the femur. The periosteum was taken from the femur epiphyses and diaphyses of 32 rats. The animals were sacrificed 1, 2, 3, 4 and 8 weeks after periosteal stripping. Intense cell proliferation occurred in the first week. After two weeks, a thick tissue layer formed by osteoblasts and undifferentiated cells was seen at the two donor sites. Eight weeks after, the periosteum had the same aspect as that from the right femur, which was used as control. Histomorphometric analysis showed that periosteal regeneration was significantly different between epiphyses and diaphyses. Periosteal regeneration at donor site located in epiphyses presented greater proliferation and better osteogenic activity than that observed in diaphyses.
Assuntos
Regeneração Óssea , Transplante Ósseo , Diáfises/transplante , Epífises/transplante , Periósteo/transplante , Animais , Divisão Celular , Diáfises/citologia , Diáfises/fisiologia , Epífises/citologia , Epífises/fisiologia , Fêmur , Masculino , Osteogênese , Periósteo/citologia , Periósteo/fisiologia , Ratos , Ratos Wistar , Fatores de TempoRESUMO
Foi avaliado o comportamento mecânico do fêmur de ratas imaturas e próximas da maturidade, em ensaios de flexao, com forças aplicadas na face côncava e convexa da diáfise do osso. A idade dos animais era de 25 e de 79 dias. Oitenta animais foram casualmente distribuídos em quatro grupos, de acordo com a idade e a superfície testada. Os ensaios foram em flexao e realizados à temperatura ambiente, após período de estocagem a -20º em freezer, durante um mês. Das curvas tensao x deformaçao foram obtidos: módulo de elasticidade, tensao máxima, tensao no limite de proporcionalidade e energia absorvida na fase elástica. Os dados mostraram que os animais próximos da maturidade tinham ossos mais fortes quando testados em flexao, mas quando foi comparada, para a mesma idade, a resistência aplicada na face côncava e convexa da diáfise, a maioria dos parâmetros nao apresentou diferenças significativas. Isto levou à conclusao de que o osso praticamente tem a mesma resistência aos esforços de flexao aplicados a favor e contra a concavidade. Postulou-se que pode haver rearranjo da arquitetura óssea interna no sentido de compensar alguma desvantagem mecânica em um dos sentidos.