Calcium bioavailability was investigated using isotopic intestinal absorption, and balance study techniques with bone mineralization and biomechanics as endpoint determinants of calcium utilization. In experiment 1, lactose enhancement of paracellular calcium absorption was confirmed, and it was suggested that a critical luminal concentration of lactose was necessary for its action. Despite the enhanced intestinal absorption of calcium in animals fed the 50% lactose containing diet, bone mineralization was not different from controls; and further, a decrease in bone strength of these animals was found to be secondary to nutrient malabsorption. In this study, there was no evidence to indicate a difference in the bioavailability of calcium from milk (colloidal) or yogurt (ionized) sources. In experiment 2, the absorption of calcium from the ileum was significantly enhanced in[formula omitted] normal Wistar rats fed milk protein diets containing casein as compared to whey and soy protein diets. The increase in absorbed calcium was shown to have little physiological significance in bone mineralization and biomechanics when animals were fed a diet adequate in dietary calcium. In experiment 3, paracellular calcium absorption was similar between genetically spontaneously hypertensive (SHR) and normotensive control Wistar-Kyoto (WKY) rats, suggesting that differences in calcium metabolism between these two strains was not due to differences in ileal calcium transport. The effect of casein and soy protein diets containing high (2.0%), adequate (0.5%) and low (0.05%) levels of calcium, respectively on calcium bioavailability and subsequent utilization was determined in SHR and WKY animals. Ileal calcium absorption was greater in casein fed animals than those fed soy at the adequate and low levels of calcium. Femur calcification was enhanced by casein diets at the high and medium levels of dietary calcium only. Femur biomechanics were not influenced by dietary protein source, but were however, adversely affected by the low dietary calcium level. In experiment 4, the effect of dietary fortification with casein phosphopeptides (CPP) was investigated in casein and soy fed SHR animals. CPP added to casein and soy protein diets appeared to result in a greater ileal absorption of calcium. This increase in calcium bioavailability from the casein diet had little effect however, on bone mineralization and biomechanical strength, due to the excretion of excess absorbed calcium. In experiment 5, severe thermal processing of dietary proteins was shown to reduce in vitro digestibility. Animals fed heat denatured casein and soy diets exhibited reduced intestinal calcium absorption, calcium balance as well as bone mineralization and biomechanics. These effects were influenced by the nutrient malabsorption experienced by these animals. In experiment 6, a low (6%) protein, low phosphorus diet resulted in decreased food intake and animal growth. However, ileal calcium absorption (% dose) was similar between 6% and 20% protein fed animals. A low level of dietary protein influenced calcium balance and utilization for bone mineralization and biomechanical strength. These results indicate that paracellular calcium absorption may not necessarily equate with those obtained from a calcium balance study. Notwithstanding, calcium bioavailability from the ileum was shown to be enhanced in animals fed casein, which was likely due to the production of bioactive peptides (CPP) that are involved in sequestering calcium and retaining it in a soluble form. By reducing protein digestibility with heat denaturation, this effect was lost. Reducing the protein content in the diet however, did not reduce the enhancement of calcium bioavailability observed in casein fed animals. Finally, bone mineralization and biomechanical parameters were shown to be sensitive indicators of calcium utilization from diets that varied in calcium content or bioavailability of this mineral. / Land and Food Systems, Faculty of / Graduate

In this study different bioactive agents were used to investigate their single and combined effects on biomechanical properties of osteoporotic bone. Estrogen, the most common hormon replacement therapy (HRT) agent, was used in single and combined with raloxifen, a well known osteoporosis drug. Despite their high clinical uses, they have not been tried before, in combination. They act as agonist of each other in bone and antagonist of each other in uterus and mammary glands. Hence it was expected to prevent HRT side effects by using combinations while enhancing the healing on osteoporotic bone. So, the study was designed to see the interaction effects of these two agents on bone and uterus, to observe the mechanical behaviour upto fracture, and to investigate the bone mechanical properties by strain gauges and bending theory with ovariectomized rat model. Second approach to osteoporosis treatment, VitK2 was chosen to be used alone or in combination with raloxifen in same model. Although recent studies mentioned the effects of VitK2 on bone, its rebuilding or repair effect was not completely established. So, VitK2-bone relation was aimed to be clarified with the project.VitK2 raloxifen combination was also a new study, that has not been carried out so far. As a result of mechanical tests, it was found that E+R combination is the most effective treatment. All treatment&amp / #8217 / s were resulted in numerically (though not statistically significant) higher values on femur mechanical properties, and significantly better on tibia compared to the untreated controls. VitK2 performs well in energy absorption upto fracture, but worse in others (PL, YL etc.) compared to other treatments indicating that it plays a specific role in modifying bone structure thus, rendering bone stronger under high stress. However, similar to estrogen case, its combination with raloxifen performs better than its individual administration. With combinations it was aimed to reduce the adverse effects of estrogen on uterus and mammary glands by using raloxifen. This idea appears to be achieved with better histological results of uterus in combinations than estrogen groups. Additionally it was observed that direct strain data obtained by strain gauge experiments can be more informative than theoretical model in calculating modulus of elasticity, and shown that shear contribution can be neglected if depth/span ratio and set up dimensions properly chosen. Biochemical analysis of the blood showed an increment in bone formation (ALP activity) compared to both controls. ALP activity was the highest in R group, which was lower in combinations. Thus existence of a different mechanism in osteoporotic bone repair in combinations was suggested.

The purpose of this study was to develop material properties of human rib cortical bone using dynamic tension coupon testing. This study presents 117 human rib cortical bone coupon tests from six cadavers, three male and three female, ranging in age from 18 to 67 years old. The rib sections were taken from the anterior, lateral, and posterior regions on ribs 1 through 12 of each cadaver's rib cage. The cortical bone was isolated from each rib section with a low speed diamond saw, and milled into dog bone shaped tension coupons using a small computer numerical control machine. A high-rate servo-hydraulic Material Testing System equipped with a custom slack adaptor, to provide constant strain rates, was used to apply tension loads to failure at an average rate of 0.5 strains/sec. The elastic modulus, yield stress, yield strain, ultimate stress, ultimate strain, and strain energy density were determined from the resulting stress versus strain curves. The overall average of all cadaver data gives an elastic modulus of 13.9 GPa, a yield stress of 93.9 MPa, a yield strain of 0.883 %, an ultimate stress of 124.2 MPa, an ultimate strain of 2.7 %, and a strain energy density of 250.1 MPa-strain. For all cadavers, the plastic region of the stress versus strain curves was substantial and contributed approximately 60 strain % to the overall response and over 80 strain % in the tests with the 18 year old cadaver. The rib cortical bone becomes more brittle with increasing age, shown by an increase in the modulus (p < 0.01) and a decrease in peak strain (p < 0.01). In contrast to previous three-bending tests on whole rib and rib cortical bone coupons, there were no significant differences in material properties with respect to rib region or rib level. When these results are considered in conjunction with the previous three-point bending tests, there is regional variation in the structural response of the human rib cage, but this variation appears to be primarily a result of changes in the local geometry of each rib while the material properties remain nearly constant within an individual. / Master of Science

No description available.

Made available in DSpace on 2016-06-02T19:22:50Z (GMT). No. of bitstreams: 1 2036.pdf: 748244 bytes, checksum: f28f7da3d00f1b29890db0e264cd0b46 (MD5) Previous issue date: 2008-08-29 / Universidade Federal de Sao Carlos / The mercury is used in the industry, medicine, agriculture and other fields. However, little is known about its involvement with the bone metabolism. The aim of this study was to evaluate the physical, biochemical and biomechanical bone parameters in adult rats contaminated with mercuric chloride during the development phase. The animals were separated as control group: 10 male rats treated with saline 0.9% (0,1 ml/100g BW) and contaminated group: 8 male rats treated with mercuric chloride (2.5 mg/Kg BW). The animals were treated during 60 days, 5 days/week, by stomacal gavage. The body weight, femoral length and diaphysis thickness were measured. The mechanical properties (maximum and failure forces, stiffness and yield) of femurs were evaluated by the three-point bending test using the universal machine Instron model 4444. The bone volume was estimated by the Archimedes Principle. The wet and ash weight were also determined. The body weight, length and minor diameter of the femurs were not different between the groups; however the major diameter increased in contaminated group (p=0.0002). It was observed an increase (p=0.0044) of bone volume and a decrease of the bone mineral density (p=0.0009) and of the percentage of mineral material (p=0.0001) of the femurs of the contaminated group. The bone response to biomechanical test was similar in both groups. The rat contamination with mercuric chloride in the dose of 2.5 mg/Kg BW caused small alteration in the development of bones, as observed by the biometrical and biophysical parameters analyzed. However these alterations were not enough to induce modification of the biomechanical and biochemical parameters. / O mercúrio é utilizado na indústria, medicina, agricultura e outros campos. Pouco se sabe sobre seu envolvimento com o metabolismo ósseo. O objetivo desse estudo foi avaliar possíveis alterações físicas, bioquímicas e biomecânicas ósseas em ratos adultos intoxicados com cloreto mercúrico durante seu desenvolvimento. Os animais foram divididos em grupo contaminado e controle, sendo 10 ratos machos tratados com salina 0,9% (0,1 ml/100g PC) e 8 ratos machos tratados com cloreto mercúrico (2,5 mg/Kg PC), durante 5 dias/semana, por 60 dias pelo método de gavagem gástrica. O peso corporal, comprimento femoral e espessura das diáfises femorais foram mensurados. As propriedades (força máxima e de ruptura, rigidez e resiliência) dos fêmures foram mensuradas através do teste de flexão à três pontos em uma máquina universal modelo Instron 4444. Através do Princípio de Arquimedes, calculou-se o volume ósseo, e a partir deste parâmetro as densidades óssea e mineral foram determinadas utilizando as propriedades físicas: peso seco, peso imerso, peso úmido e das cinzas. O peso corporal, comprimento e o diâmetro menor do fêmur não foram diferentes entre os grupos, porém o diâmetro maior aumentou no grupo contaminado (p=0,0002). Houve aumento do volume ósseo (p=0,0044) e diminuição da densidade mineral (p=0,0009) e percentual de material mineral (p=0,0001) dos fêmures do grupo contaminado, porém essas alterações não foram suficientes para provocar alteração dos parâmetros biomecânicos. A contaminação com cloreto mercúrico na dose de 2,5 mg/Kg PC causou pequena alteração do desenvolvimento ósseo dos ratos, como pode ser observado pela alteração dos parâmetros biométricos e biofísicos, mas não suficiente para alterar os parâmetros bioquímicos e biomecânicos do fêmur.

Made available in DSpace on 2016-06-02T19:22:51Z (GMT). No. of bitstreams: 1 2339.pdf: 646629 bytes, checksum: a664e5d6f2b2d647db3059c99759df5b (MD5) Previous issue date: 2009-04-09 / Universidade Federal de Sao Carlos / Lead is a ubiquitous pollutant in the environmental ecosystem which distribution is mainly anthropogenic, come from burning fossil fuels, mining and various industrial products. There is little knowledge of the involvement of this element on the bone metabolism. This study aimed to determine possible changes in adult rat bone, contaminated with lead acetate during the development phase, through the incorporation of lead in the tissue. Biometric, biophysical, and biomechanical bone parameters were analyzed. The animals were divided into 3 groups: control, 9 rats treated with saline 0.9% (0.1 ml/100g BM) and contaminated groups C-100 and C-200 with 10 animals each, poisoned with lead acetate (100 and 200 mg / kg BM, respectively), once per week for 8 weeks by gastric gavage method. The incorporation of lead was examined with scanning electron microscopy and the concentration of this element in bone tissue with atomic absorption spectrometry with flame. We calculated the bone volume, and from this parameter the bone density was determined. The biomechanical properties of femurs were obtained by three points bending test. Contamination with lead acetate promoted incorporation and increased the concentration of lead in bone for the two doses tested, however were not sufficient to cause changes in the somatic and bone development of these animals. The dose of 100 mg / kg BM was not enough to cause bone changes and the dose of 200 mg / kg BM caused reduced bone density and strength. Therefore, the results indicate the ability of this element in damage the quality of the bone and maybe, serve as a source for endogenous subsequent contamination. / Chumbo é um poluente ubíquo no ecossistema cuja distribuição ambiental é principalmente antropogênica, oriunda da queima de combustíveis fósseis, mineração e fabricações industriais diversas. Há pouco conhecimento do envolvimento deste elemento sobre o metabolismo ósseo. O objetivo deste estudo foi estabelecer possíveis alterações ósseas em ratos adultos, contaminados com acetato de chumbo durante a fase de desenvolvimento, por meio da incorporação de chumbo neste tecido. Foram analisados parâmetros biométricos, biofísicos, e biomecânicos ósseos. Os animais foram divididos em 3 grupos: controle, com 9 ratos tratados com salina 0,9% (0,1 ml/100g MC) e contaminados C-100 e C-200 com 10 animais cada, intoxicados com acetato de chumbo (100 e 200 mg/kg MC, respectivamente), 1 vez por semana, por 8 semanas pelo método de gavagem gástrica. A incorporação de chumbo foi analisada com microscopia eletrônica de varredura e as concentrações deste elemento no tecido ósseo com espectrometria de absorção atômica com chama. Calculou-se o volume ósseo, e a partir deste parâmetro a densidade óssea foi determinada. As propriedades biomecânicas dos fêmures foram obtidas pelo teste de flexão a três pontos. A contaminação com acetato de chumbo promoveu incorporação e aumento da concentração de chumbo no tecido ósseo para as duas doses testadas, entretanto não foram suficientes para provocar alterações no desenvolvimento somático e ósseo destes animais. A dose de 100 mg/kg MC não foi suficiente para provocar alterações ósseas e a dose de 200 mg/kg MC provocou redução da densidade e resistência óssea. Portanto, os resultados apontam a capacidade deste elemento em prejudicar a qualidade do tecido ósseo e talvez servir como fonte endógena para contaminações subseqüentes.

Made available in DSpace on 2016-06-02T19:23:00Z (GMT). No. of bitstreams: 1 5830.pdf: 3124907 bytes, checksum: 55c12c9ea3515d048b2237215c49333a (MD5) Previous issue date: 2014-05-06 / Financiadora de Estudos e Projetos / Resveratrol (trans 3,5,4 'trihydroxystilbene) is a polyphenol found in some plants and fruits. There are indications that it may be associated with the prevention of osteoporosis due to its action similar to a SERM (Selective Estrogen Receptor Modulators), a substance used to treat osteoporosis (among other diseases) in women whose use of hormone replacement therapy does not is indicated. However, more specific information about their effect in various quotas of bone tissue is still scarce. The aim of this study was to evaluate the ability of resveratrol to protect against bone changes characteristics of estrogen deficit in young adult ovariectomized rats. Were utilized 30 animals (Wistar rats) distributed into 3 groups: intact group (INT) with 10 intact animals, ovariectomized group (OVX) with 10 ovariectomized animals treated with a saline and dimethylsulfoxide (DMSO) solution, ovariectomized + resveratrol group (OVX + RES) with 10 ovariectomized animals treated with a resveratrol, saline and DMSO solution [0.7 mg/kg BW (body weight)], 7 times a week, for 12 weeks. Biometric, biophysical, biomechanical, microtomographical and radiographic density parameters were analyzed from bones with higher cortical (femur) and trabecular quota (vertebrae). The biomechanical properties of femurs were obtained by the three-point bending test and the lumbar vertebrae obtained by bone compression test. Lumbar vertebrae were used to perform the microtomographical analysis and radiographic density analysis. The ovariectomized rats gained more body weight and had lower bone density and radiographic density, and also showed reduction of microtomographical parameters when compared to the intact group. The biomechanical parameters of femurs did not change in neither group. The animals treated with resveratrol did not shown decrease in microtomographical parameters and bone density of the vertebrae as the untreated group. Therefore, the results suggest resveratrol as a potential protector of ovariectomy induced spoliation of bone tissues with greater trabecular quota. / Resveratrol (trans 3,5,4 -trihidroxiestilbeno) é um polifenol encontrado em algumas plantas e frutos. Há indícios de que ele possa ser associado à prevenção da osteoporose devido a sua ação similar a de um SERM (Selective Estrogen Receptor Modulators), substância utilizada para tratamento da osteoporose (entre outras doenças) em mulheres cujo o uso da Terapia de Reposição Hormonal não é indicado. Entretanto, informações mais específicas sobre o seu efeito em diferentes contingentes do tecido ósseo ainda são escassas. O objetivo deste estudo foi avaliar a capacidade do resveratrol de proteger contra as alterações ósseas características da deficiência de estrógeno em ratas adultas jovens ovariectomizadas. Foram utilizados 30 animais (ratas Wistar) distribuidos em 3 grupos: grupo intacto (INT) com 10 animais intactos, grupo controle ovariectomizadas (OVX) com 10 animais ovariectomizados tratados com uma solução de salina e Dimetilsulfóxido (DMSO), grupo ovariectomizadas + resveratrol (OVX + RES) com 10 animais ovariectomizados tratados com uma solução de resveratrol, salina e DMSO intraperitonealmente [0,7 mg/kg MC (massa corpórea)], 7 vezes por semana, por 12 semanas. Foram analisados os parâmetros biométricos, biofísicos, biomecânicos ósseos, microtomográficos e de densidade radiográfica de ossos com maior contingente cortical (fêmures) e trabecular (vértebras). As propriedades biomecânicas dos fêmures foram obtidas pelo teste de flexão a três pontos e das vértebras lombares obtidas pelo teste de compressão óssea. Foram utilizadas vértebras lombares para a realização da análise microtomográfica e de densidade radiográfica. As ratas ovariectomizadas apresentaram maior ganho de massa corporal e diminuição da densidade óssea e densidade radiográfica, além de redução dos parâmetros microtomográficos quando comparadas ao grupo intacto. Os parâmetros biomecânicos dos fêmures não sofreram alteração em nenhum dos grupos. Os animais tratados com resveratrol não apresentaram a diminuição dos parâmetros microtomográficos e de densidade óssea das vertebras como os não tratados. Portanto, os resultados apontam o resveratrol como potencial protetor do tecido ósseo com maior contingente trabecular da espoliação induzida pela ovariectomia.

No description available.

Made available in DSpace on 2016-06-02T19:22:09Z (GMT). No. of bitstreams: 1 5384.pdf: 3646799 bytes, checksum: cae5edc100d549896cd5997951a21e99 (MD5) Previous issue date: 2013-06-21 / Universidade Federal de Sao Carlos / Lead (Pb) is an ubiquitous pollutant in the environmental ecosystem. Its distribution is mainly anthropogenic, coming from the burning of fossil fuels, mining and production of various industrial products. There is little knowledge of the effect of the Pb and its compounds on bone metabolism as well as potential therapies for frames contamination related to the lead. The aim of this study was to determine possible changes in the bones of adult rats contaminated with lead acetate correlated them to the effects of hydroxyapatite and the resveratrol in adult rats contaminated with lead acetate. The biomechanical, biometric, biophysical, microtomographic bone parameters, the radiographic density, the concentration of Pb and metalloproteinase activity in bone tissue were analyzed. The animals were distributed into 6 groups of 8 rats each: control, treated with saline 0.9% (0.1 ml/100g BM), hydroxyapatite, treat with hydroxyapatite (100 mg/kg BM), contaminated, treated with lead acetate (250 mg/kg BM), contaminated + hydroxyapatite, treated with lead acetate (250mg/kg BM) and hydroxyapatite (100mg/kg BM); the treatments were carry out once per week for 8 weeks by gastric gavage. The groups contaminated + resveratrol, treated with lead acetate (250 mg/kg BM) and resveratrol (0.7 mg/kg BM ) and DMSO, treated with dimethylsulfoxide (0.1 ml/100g BM), 5 times a week for 8 weeks by intraperitoneal injections. The contamination with lead acetate promoted incorporation of it in bone tissue leading to a reduction in bone strength of femurs and vertebrae, reduction of vertebral trabecular contingent, and increased activity of metalloproteins type 2. The treatment with hydroxyapatite (100 mg/kg MC) as well with resveratrol (0.7 mg/kg MC) prevented the deleterious effects of lead contamination at the proposed dose, including reducing the activity values of metalloproteins type 2 to levels similar to that of control group. Therefore, the results point to hydroxyapatite and resveratrol as potential treatment agents in lead contamination, preventing damage to the quality of bone tissue caused by this element. / Chumbo (Pb) é um poluente ubíquo no ecossistema cuja distribuição ambiental é principalmente antropogênica, oriunda da queima de combustíveis fósseis, mineração e fabricações industriais diversas. Há pouco conhecimento do envolvimento do Pb e seus compostos sobre o metabolismo ósseo bem como das potenciais terapias para quadros de contaminação relacionadas ao chumbo. O objetivo deste estudo foi avaliar as alterações ósseas causadas pelo acetato de chumbo correlacionado-as aos efeitos da hidroxiapatita e do resveratrol em ratos adultos contaminados com acetato de chumbo. Foram analisados os parâmetros biomecânicos, biométricos, biofísicos, microtomográficos ósseos, a densidade radiográfica, a concentração de Pb e a atividade de metaloproteinases no tecido ósseo. Os animais foram distribuidos em 6 grupos com 8 ratos cada: controle, tratados com salina 0,9% (0,1 ml/100g MC), hidroxiapatita, tratados com hidroxiapatita (100 mg/kg MC), contaminado, tratados com acetato de chumbo (250 mg/kg MC) e contaminado + hidroxiapatita, tratados com acetato da chumbo (250 mg/kg MC) e hidroxiapatita (100 mg/kg MC), 1 vez por semana, por 8 semanas pelo método de gavagem gástrica. Grupo contaminado + resveratrol, tratados com acetato da chumbo (250 mg/kg MC) e resveratrol (0,7 mg/kg MC) e DMSO, tratado com dimetilsulfóxido (0,1 ml/100g MC), 5 vezes por semana, por 8 semanas por meio de injeções intraperitoneais. A contaminação com acetato de chumbo promoveu incorporação de chumbo no tecido ósseo provocando redução da resistência óssea de fêmures e vértebras e do contingente trabecular das vértebras analisadas, promovendo aumento da atividade de metaloproteinases tipo 2. Tanto o tratamento com 100 mg/kg MC de hidroxiapatita quanto o de 0,7 mg/kg MC de resveratrol preveniram os efeitos deletérios da contaminação com chumbo na dose proposta, inclusive reduzindo os valores de atividade de metaloproteinases tipo 2 para níveis semelhantes ao do grupo controle. Portanto, os resultados apontam a hidroxiapatita e o resveratrol como potenciais agentes de tratamento preventivo na contaminação com chumbo, evitando os prejuízos à qualidade do tecido ósseo provocadas por este elemento.