Made available in DSpace on 2014-06-11T19:23:43Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-05-29Bitstream added on 2014-06-13T18:19:52Z : No. of bitstreams: 1 zanetti_nm_me_jabo.pdf: 847982 bytes, checksum: c0960b3258ff6b50bfdd4f45e2574a53 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Este estudo teve como objetivo avaliar comparativamente os efeitos do emprego do ultrassom pulsado de baixa intensidade e da proteína morfogenética óssea (rhBMP-2) sobre a consolidação do osso in vivo. Foram realizadas ostectomias bilaterais do rádio de 24 coelhos machos, da raça Nova Zelândia Branco, seguido da análise qualitativa (avaliação clínica, histológica e radiográfica) e quantitativa (histomorfometria óssea e bioquímica) da falha óssea preenchida ou não com gel de quitosana. Denominaram-se seis grupos experimentais com quatro animais cada (GI – grupo controle, GII – grupo ultrassom, GIII – grupo quitosana, GIV – grupo quitosana e ultrassom, GV – grupo quitosana e rhBMP-2 e GVI – grupo quitosana, rhBMP-2 e ultrassom). As avaliações radiográficas e a mensuração da fosfatase alcalina sérica foram executadas durante o período experimental. Os fragmentos de tecido provenientes da falha óssea dos coelhos sacrificados no 30o e 45o dia foram submetidos à avaliação histológica e histomorfométrica. Os diferentes métodos de avaliação empregados neste estudo demonstraram que o preenchimento do defeito ósseo foi superior nos casos em que foi empregada a terapia ultrassônica associada à implantação do gel ativado com a proteína osteoindutora. Os coelhos que receberam o implante livre da proteína (GIII e GIV) tiveram o processo de reparo ósseo comprometido. Foi possível concluir que o ultrassom acelerou o preenchimento da falha óssea e que o gel de quitosana, embora tenha induzido processo inflamatório, foi capaz de carrear a rhBMP-2, permitindo a ação sinérgica entre o ultrassom e a proteína. / This comparative study evaluated in vivo responses of bone healing under low intensity pulsed ultrasound and bone morphogenetic protein (rhBMP-2) treatment in experimental bone defects filled or not with chitosan gel. Twenty four New Zealand White rabbits were assigned in six experimental groups, four animals each (GI – control group, GII – ultrasound group, GIII – chitosan group, GIV – chitosan plus ultrasound group, GV – chitosan with rhBMP-2 and GVI – chitosan with rhBMP-2 plus ultrasound). It was performed a qualitative (radiographic, histological and clinical evaluation) and quantitative research (histomorphometrical and biochemical analysis) of bone healing. The radiographic and serum alkaline phosphatase evaluation was performed during the experimental period. Histological and bone histomorphometry was applied for bone sample evaluation from sacrificed rabbits (30th and 45th days). The different evaluation methods used in this study showed that defect filling was improved when the treatment was based on the association between ultrasound and activated chitosan gel. The bone defects filled with non-activated gel (GIII and GIV) showed a delay in bone healing. This study had demonstrate that low intensity ultrasound improves bone healing process, that chitosan gel is a good carrier for rhBMP-2 even when it induced an inflammatory reaction, allowing a synergetic effect between ultrasound and protein.

Orientador: João Guilherme Padilha Filho / Banca: Paola Castro Moraes / Banca: Patricia Popak Giordano / Resumo: Este estudo teve como objetivo avaliar comparativamente os efeitos do emprego do ultrassom pulsado de baixa intensidade e da proteína morfogenética óssea (rhBMP-2) sobre a consolidação do osso in vivo. Foram realizadas ostectomias bilaterais do rádio de 24 coelhos machos, da raça Nova Zelândia Branco, seguido da análise qualitativa (avaliação clínica, histológica e radiográfica) e quantitativa (histomorfometria óssea e bioquímica) da falha óssea preenchida ou não com gel de quitosana. Denominaram-se seis grupos experimentais com quatro animais cada (GI - grupo controle, GII - grupo ultrassom, GIII - grupo quitosana, GIV - grupo quitosana e ultrassom, GV - grupo quitosana e rhBMP-2 e GVI - grupo quitosana, rhBMP-2 e ultrassom). As avaliações radiográficas e a mensuração da fosfatase alcalina sérica foram executadas durante o período experimental. Os fragmentos de tecido provenientes da falha óssea dos coelhos sacrificados no 30o e 45o dia foram submetidos à avaliação histológica e histomorfométrica. Os diferentes métodos de avaliação empregados neste estudo demonstraram que o preenchimento do defeito ósseo foi superior nos casos em que foi empregada a terapia ultrassônica associada à implantação do gel ativado com a proteína osteoindutora. Os coelhos que receberam o implante livre da proteína (GIII e GIV) tiveram o processo de reparo ósseo comprometido. Foi possível concluir que o ultrassom acelerou o preenchimento da falha óssea e que o gel de quitosana, embora tenha induzido processo inflamatório, foi capaz de carrear a rhBMP-2, permitindo a ação sinérgica entre o ultrassom e a proteína. / Abstract: This comparative study evaluated in vivo responses of bone healing under low intensity pulsed ultrasound and bone morphogenetic protein (rhBMP-2) treatment in experimental bone defects filled or not with chitosan gel. Twenty four New Zealand White rabbits were assigned in six experimental groups, four animals each (GI - control group, GII - ultrasound group, GIII - chitosan group, GIV - chitosan plus ultrasound group, GV - chitosan with rhBMP-2 and GVI - chitosan with rhBMP-2 plus ultrasound). It was performed a qualitative (radiographic, histological and clinical evaluation) and quantitative research (histomorphometrical and biochemical analysis) of bone healing. The radiographic and serum alkaline phosphatase evaluation was performed during the experimental period. Histological and bone histomorphometry was applied for bone sample evaluation from sacrificed rabbits (30th and 45th days). The different evaluation methods used in this study showed that defect filling was improved when the treatment was based on the association between ultrasound and activated chitosan gel. The bone defects filled with non-activated gel (GIII and GIV) showed a delay in bone healing. This study had demonstrate that low intensity ultrasound improves bone healing process, that chitosan gel is a good carrier for rhBMP-2 even when it induced an inflammatory reaction, allowing a synergetic effect between ultrasound and protein. / Mestre

Este estudo analisou a influência de diferentes superfícies de titânio na adesão, proliferação e diferenciação de células semelhantes a osteoblastos de rato (osteo-1) em culturas, na presença ou não da proteína morfogenética óssea recombinante-2 (rhBMP-2). As células osteo-1 foram cultivadas sobre as seguintes superfícies de titânio: 1. superfície lisa, 2. superfície desgastada com partículas de areia e condicionamento ácido (SLA) e 3. superfície desgastada com partículas de areia e condicionamento ácido sob proteção de nitrogênio e armazenadas em solução isotônica de cloreto de sódio (SLActive), na presença ou não de 20 ng/ml de rhBMP-2. Foram analisadas a adesão celular em 24 horas, o conteúdo total de proteínas, o conteúdo de colágeno e a atividade de fosfatase alcalina em 7, 14 e 21 dias e a formação de nódulos calcificados em 21 dias. Os resultados mostraram que a adesão não foi influenciada nem pelo tipo de superfície nem pelo tratamento com rhBMP-2 (p=0,0936). Quando relacionamos o conteúdo total de proteínas ao número total de células, percebemos que a proliferação não foi influenciada pelo tipo de superfície de titânio, porém a adição de rhBMP-2 levou a uma redução estatisticamente significante na superfície SLA aos 21 dias (p=0,0000). Em relação à diferenciação, pudemos observar que o tipo de superfície não influenciou o conteúdo total de proteínas, o conteúdo de colágeno e a formação de nódulos calcificados em quaisquer dos períodos analisados. A atividade de fosfatase alcalina somente foi influenciada pelo tipo de superfície aos 14 dias, onde o grupo C/SLAactive apresentou valores inferiores ao grupo C/Liso (p=0,0000). A adição de rhBMP-2 promoveu uma maior influência sobre o processo de diferenciação, levando a uma redução estatisticamente significante no conteúdo total de proteínas na superfície SLA aos 21 dias (p=0,0000), a um aumento estatisticamente significante no conteúdo de colágeno na superfície SLActive no período de 7 dias (p=0,0005) e a uma diminuição estatisticamente significante na atividade de fosfatase alcalina na superfície lisa nos períodos de 14 e 21 dias, na superfície SLA aos 14 dias e na superfície SLActive aos 21 dias (p=0,0000). Somente a formação de nódulos calcificados não sofreu influência da adição de rhBMP-2. / This study has analyzed the influence of different titanium surfaces in the adhesion, proliferation and differentiation of rat osteoblast-like cells (osteo-1 culture), in the presence or not, of the recombinant bone morphogenetic protein-2 (rhBMP-2). The osteo-1 cells were grown on the following titanium surfaces: 1. smooth surface; 2. coarse grit-blasted and acid-etched surface (SLA); and 3. coarse grit-blasted and acid-etched surface under nitrogen protection, and stored in sodium chloride isotonic solution (SLActive), in the presence or not, of 20 ng/ml of rhBMP-2. It was analyzed the cell adhesion in 24 hours, the total protein content, the collagen content, and the alkaline phosphatase in 7, 14 and 21-day periods, and also the formation of calcified nodules in 21 days. The results showed that the adhesion was neither influenced by the surface type, nor by the treatment with rhBMP-2 (p=0.0936). When we related the total protein content to the total number of cells, we noticed that the proliferation was not influenced by the titanium surface type; however, the addition of rhBMP-2 led to a statistically significant reduction on the SLA surface at 21 days (p=0.0000). Concerning the differentiation, we could observe that the surface type did not influence the total content of proteins, the collagen content and the formation of calcified nodules in any of the analyzed periods. The alkaline phosphatase activity was only influenced by the surface type at 14 days, where the group C/SLActive presented lower values than the group C/Smooth (p=0.0000). The addition of rhBMP- 2 promoted a bigger influence over the differentiation process, thus leading to a statistically significant reduction in the total protein content on the SLA surface at 21 days (p=0.0000), a statistically significant increase in the collagen content on the surface SLActive in the 7-day period (p=0.0005), a statistically significant reduction in the alkaline phosphatase activity on the smooth surface in the 14 and 21-day periods, on the SLA surface at 14 days, and on the SLActive surface at 21 days (p=0.0000). Only the formation of calcified nodules did not undergo influence of the rhBMP-2 addition.

O tecido ósseo é considerado um tecido complexo e possui alta capacidade de reparação espontânea quando lesionado. Entretanto, em algumas patologias esta capacidade pode estar comprometida por diversos fatores extrínsecos e intrínsecos ao organismo. Em decorrência de sua capacidade plástica, o uso de células-tronco para terapia celular regenerativa tem se tornado uma importante ferramenta no tratamento de lesões ósseas e de doenças decorrentes da perda da densidade mineral óssea (DMO). Em contraste, o uso da Proteína Morfogenética Óssea (BMP) ganhou grande destaque pela sua eficácia em tratar doenças ósseas de caráter crônico e, quando associadas a células-tronco, trouxe um melhor resultado para tais desordens. Assim, o presente trabalho teve como objetivo avaliar a associação de célula-tronco mesenquimal de medula óssea (MSC Mesenchymal Stem Cells) e BMP-7 na regeneração óssea a partir de defeito ósseo induzido na calvária murina no 60º dia de tratamento. Foram realizadas imagens radiográficas da calvária e, após os dias estipulados, o material foi coletado para análise de microscópica. Os dados obtidos sugerem que o modelo de regeneração óssea proposto foi apropriado para avaliar a resposta terapêutica usando MSC e BMP-7, onde o cultivo e pré-diferenciação de MSC com BMP-7 produziu melhores resultados do que os outros tratamentos realizados / Bone tissue is considered a complex tissue and has high capacity for spontaneous recovery when injured. However, in some conditions this capacity can be compromised by several extrinsic and intrinsic factors to the body. Due to its plastic capacity, the use of stem cells for regenerative cell therapy has become an important tool in the treatment of bone injuries and diseases resulting from loss of bone mineral density (BMD). In contrast, the use of Bone Morphogenetic Protein (BMP) has gained wide attention for its effectiveness in treating bone diseases were chronic and brought a better outcome for such disorders when associated with stem cells. Thus, the present study aimed to evaluate the association of bone marrow mesenchymal stem cells (MSC) and BMP-7 in bone regeneration from bone defects induced in murine calvaria on the 60th day of treatment. Radiographic images of the calvaria were performed and after the stipulated days the material was collected for microscopic essays. The data obtained suggest that the proposed model of bone regeneration was appropriate to assess the therapeutic response using MSC and BMP-7, where the pre cultivation and differentiation of MSCs with BMP-7 produced better results than the other treatments performed.

Abstract Bone morphogenetic proteins (BMPs) constitute a large family of osteoinductive proteins. Different BMPs are widely used in animal experiments and increasingly in the field of bone surgery. However, the sterilization of BMPs and the choice of a suitable mode of delivery, which binds and slowly releases BMP molecules, are still under intensive investigation. The aims of this study were to evaluate the effects of ethylene oxide and gamma sterilizations and different delivery systems on the osteoinductivity of reindeer BMP extract by using heterotopic and orthopic animal models. Ethylene oxide gas (Steri-Vac 4XL, temperature 29 °C, exposure time 4 h, concentration 860 mg/l) and gamma (doses of 3.15 or 4.15 Mrad) sterilizations were used. The tested delivery systems for reindeer BMP were collagen (Lyostypt®), gelatine capsule (no.1) and composites containing collagen combined with tricalcium phosphate (TCP) or hydroxyapatite (HA) or biphasic tricalcium phosphate-hydroxyapatite (TCP/HA) or biocoral (NC) frames. The injectability of reindeer BMP was tested by using injections containing a saline or gelatine vehicle. Osteoinductivity was evaluated as ectopic bone formation in the thigh muscle pouches of mouse hind legs. The induced new bone was evaluated based on the incorporation of 45Ca or calcium yield, radiographs and histological examination three weeks after the operations. The effect of gamma sterilization on the bone healing capacity of reindeer BMP extract was evaluated in a rabbit radial bone defect model in comparison with non-sterilized reindeer BMP extract and recombinant BMP-2. Bone healing was evaluated after eight weeks based on radiographs, mechanical tests and peripheral computerized tomography (pQCT). All BMP implants induced new bone in vivo visible in radiographs, but no bone formation was seen in the control implants without reindeer BMP. Gamma sterilization did not decrease significantly the osteoinductivity of reindeer BMP extract, except when administered as an injection containing gelatine vehicle. Ethylene oxide sterilization decreased significantly the osteoinductivity of reindeer BMP extract and was significantly inferior compared to gamma sterilization. Reindeer BMP combined with collagen or composite containing collagen and TCP/HA frame induced new bone significantly better than reindeer BMP combined with composite containing collagen and TCP frame. BMP injections with gelatine or saline vehicles induced new bone effectively. Injections were easy to handle and well tolerated by the mice. Reindeer BMP extract administered with collagen carrier healed the bone defect of the rabbit radius significantly better than control implants without reindeer BMP or no treatment and its effect was comparable with rhBMP-2 treatment.

Systemic iron homeostasis is maintained by regulation of iron absorption in the duodenum, iron recycling from erythrocytes, and iron mobilization from the liver and is controlled by the hepatic hormone hepcidin. Hepcidin expression is induced via the bone morphogenetic protein (BMP) signaling pathway that preferentially uses two type I (ALK2 and ALK3) and two type II (ActRIIA and BMPR2) BMP receptors. Hemojuvelin (HJV), HFE, and transferrin receptor-2 (TfR2) facilitate this process presumably by forming a plasma membrane complex with BMP receptors. Matriptase-2 (MT2) is a protease and key suppressor of hepatic hepcidin expression and cleaves HJV. Previous studies have therefore suggested that MT2 exerts its inhibitory effect by inactivating HJV. Here, we report that MT2 suppresses hepcidin expression independently of HJV. In Hjv(-/-) mice, increased expression of exogenous MT2 in the liver significantly reduced hepcidin expression similarly as observed in wild-type mice. Exogenous MT2 could fully correct abnormally high hepcidin expression and iron deficiency in MT2(-/-) mice. In contrast to MT2, increased Hjv expression caused no significant changes in wild-type mice, suggesting that Hjv is not a limiting factor for hepcidin expression. Further studies revealed that MT2 cleaves ALK2, ALK3, ActRIIA, Bmpr2, Hfe, and, to a lesser extent, Hjv and Tfr2. MT2-mediated Tfr2 cleavage was also observed in HepG2 cells endogenously expressing MT2 and TfR2. Moreover, iron-loaded transferrin blocked MT2-mediated Tfr2 cleavage, providing further insights into the mechanism of Tfr2's regulation by transferrin. Together, these observations indicate that MT2 suppresses hepcidin expression by cleaving multiple components of the hepcidin induction pathway.

Devido as limitações relacionadas ao emprego do enxerto autólogo, o uso dos biomateriais poliméricos naturais tornou-se uma opção viável em terapias regenerativas do tecido ósseo. O objetivo desse trabalho é avaliar de forma qualitativa e quantitiva a contribuição da membrana de elastina utilizada isoladamente ou em associação a hidroxiapatita e proteína morfogenética óssea, no reparo de defeitos ósseos no crânio de ratos. Foram utilizados 49 ratos (Rattus norvegicus, Wistar), machos, com peso aproximado de 330 gramas e 4 meses de idade. Os animais foram submetidos ao procedimento cirúrgico para a criação do defeito ósseo no osso parietal esquerdo e divididos em 7 grupos com 7 animais cada. Os grupos foram implantados com os seguintes bioamateriais: grupo 1 controle (G1-C) sem implante, grupo 2 (G2-E24h) membrana de elastina 24 h, grupo 3 (G3-E24h/HA) membrana de elastina 24 h com hidroxiapatita, grupo 4 (G4-E24h/BMP) membrana de elastina 24 h com proteína morfogenética óssea, grupo 5 (G5-E96h) membrana de elastina 96 h, grupo 6 (G6-E96h/HA) membrana de elastina 96 h com hidroxiapatita, grupo 7 (G7-E96h/BMP) membrana de elastina 96 h com proteína morfogenética óssea. Após a morte indolor induzida em 6 semanas, as calotas cranianas foram retiradas para análise macroscópica, radiográfica, histológica e morfométrica. As análises macroscópicas, radiográficas e histológicas demonstraram a biocompatibilidade dos biomateriais utilizados. As médias e desvios-padrão do volume percentual relativo de osso neoformado nos defeitos cranianos dos grupos G1 a G7 foram 7,87±2,53; 24,01±0,55; 9,59±1,27; 31,31±6,37; 19,77±2,62; 7,31±2,43; 43,25±3,72, respectivamente. Os biomateriais mostraram-se biocompatíveis e o grupo 7 (G7-E96h/BMP) resultou na maior neoformação óssea. / Due to the limitations related to the use of autologous grafts, the use of natural polymeric biomaterials has become a viable option in regenerative therapies of bone tissue. The objective of this dissertation is to evaluate in qualitative and quantitative way the contribution of the elastin matrice used alone or in combination with hydroxyapatite and bone morphogenetic protein in the repair of bone defects in the skull of rats. Were use 49 Mices (Rattus norvegicus, Wistar), weighting approximately 330 grams and 4 months of age, were used. The animals were submitted to the surgical procedure to create the bone defect in the left parietal bone and divided into 7 groups with 7 animals each. The groups were implanted with the following biomaterials: group 1 control (G1-C) without biomaterial, group 2 (G2-E24h) 24 h elastin membrane, group 3 (G3-E24h/HA) 24 h elastin membrane with hydroxyapatite, Group 4 (G4-E24h/BMP) elastin membrane 24 h with bone morphogenetic protein, group 5 (G5-E96h) elastin membrane 96 h, group 6 (G6- E96h/HA) elastin membrane 96 h with hydroxyapatite, group 7 (G7-E96h/BMP) 96 h elastin membrane with bone morphogenetic protein. After painless death induced at 6 weeks, the skull caps were removed for macroscopic, radiographic, histological and morphometric analysis. Macroscopic, radiographic and histological analysis demonstrated the biocompatibility of the biomaterials used. The mean and standard deviations of the relative percentage volume of newly formed bone in the cranial defects of the G1 to G7 groups were 7,87±2,53; 24,01±0,55; 9,59±1,27; 31,31±6,37; 19,77±2,62; 7,31±2,43; 43,25±3,72, respectively. The implanted biomaterials were shown to be biocompatible and the group 7 (G7-E96h/BMP) resulted with greater bone neoformation.

O tecido ósseo é considerado um tecido complexo e possui alta capacidade de reparação espontânea quando lesionado. Entretanto, em algumas patologias esta capacidade pode estar comprometida por diversos fatores extrínsecos e intrínsecos ao organismo. Em decorrência de sua capacidade plástica, o uso de células-tronco para terapia celular regenerativa tem se tornado uma importante ferramenta no tratamento de lesões ósseas e de doenças decorrentes da perda da densidade mineral óssea (DMO). Em contraste, o uso da Proteína Morfogenética Óssea (BMP) ganhou grande destaque pela sua eficácia em tratar doenças ósseas de caráter crônico e, quando associadas a células-tronco, trouxe um melhor resultado para tais desordens. Assim, o presente trabalho teve como objetivo avaliar a associação de célula-tronco mesenquimal de medula óssea (MSC Mesenchymal Stem Cells) e BMP-7 na regeneração óssea a partir de defeito ósseo induzido na calvária murina no 60º dia de tratamento. Foram realizadas imagens radiográficas da calvária e, após os dias estipulados, o material foi coletado para análise de microscópica. Os dados obtidos sugerem que o modelo de regeneração óssea proposto foi apropriado para avaliar a resposta terapêutica usando MSC e BMP-7, onde o cultivo e pré-diferenciação de MSC com BMP-7 produziu melhores resultados do que os outros tratamentos realizados / Bone tissue is considered a complex tissue and has high capacity for spontaneous recovery when injured. However, in some conditions this capacity can be compromised by several extrinsic and intrinsic factors to the body. Due to its plastic capacity, the use of stem cells for regenerative cell therapy has become an important tool in the treatment of bone injuries and diseases resulting from loss of bone mineral density (BMD). In contrast, the use of Bone Morphogenetic Protein (BMP) has gained wide attention for its effectiveness in treating bone diseases were chronic and brought a better outcome for such disorders when associated with stem cells. Thus, the present study aimed to evaluate the association of bone marrow mesenchymal stem cells (MSC) and BMP-7 in bone regeneration from bone defects induced in murine calvaria on the 60th day of treatment. Radiographic images of the calvaria were performed and after the stipulated days the material was collected for microscopic essays. The data obtained suggest that the proposed model of bone regeneration was appropriate to assess the therapeutic response using MSC and BMP-7, where the pre cultivation and differentiation of MSCs with BMP-7 produced better results than the other treatments performed.

Microparticles produced from kafirin, the sorghum grain prolamin protein, by molecular selfassembly using coacervation with acetic acid solvent are vacuolated. They have shown considerable potential for encapsulation of antioxidants and for preparation of high quality free-standing bioplastic films. However, the functional quality of these kafirin microstructures needs to be improved to exploit their potential application, particularly as biomaterials. Wet heat, transglutaminase and glutaraldehyde treatments were used to modify the physical structure and chemical properties of the kafirin microstructures. Heat treatment (50–96°C) increased microparticle average size by up to four-fold to ≈20 μm, probably due to disulphide cross-linking of kafirin proteins. The vacuoles within these microparticles enlarged up to >10-fold, probably due to greater expansion of air within the microparticles with higher temperature, as the vacuoles are probably footprints of air bubbles. As with heat treatment, glutaraldehyde (10–30%) treatment resulted in oval microparticles, up to about four-fold larger than the control, probably due to covalent glutaraldehyde-polypeptide linkage. Transglutaminase (0.1–0.6%) treatment had only slight effect on the size and shape of microparticles, probably because kafirin has very low lysine content, inhibiting transglutaminase-catalysed cross-linking through ε-(-glutamyl)-lysine bonding. Surface morphology using atomic force microscopy indicated that the microparticles apparently comprised coalesced nanostructures. With heat and transglutaminase treatments, the microparticles seemed to be composed of round nanostructures that coalesced into random irregular shapes, indicative of non-linear protein aggregation. In contrast, with glutaraldehyde treatment, the nanostructures were spindle-shaped and had a unidirectional orientation, probably due to linear alignment of the nanostructures controlled by glutaraldehyde-polypeptide linkage. Thin (<50 μm) films prepared from kafirin microparticles and conventional cast kafirin films were compared in terms of their water stability and other related properties. Films cast from microparticles were more water-stable compared to conventional kafirin films, probably because the large vacuoles within the kafirin microparticles may have enhanced protein solubility in the casting solution, thereby improving the film matrix cohesion. The films prepared from microparticles treated with glutaraldehyde were more water-stable compared to the control, despite the loss of plasticizer, probably due to formation of the covalent glutaraldehyde-polypeptide linkages. The potential of modified kafirin microparticles to bind bone morphogenetic protein-2 (BMP- 2) was investigated. Compared to a collagen standard, the BMP-2 binding capacity of control, heat-treated, transglutaminase-treated and glutaraldehyde-treated kafirin microparticles were 7%, 18%, 34% and 22% higher, respectively, probably mainly due to the vacuoles within the microparticles creating greater binding surface area. The safety, biodegradability and effectiveness of kafirin microparticle film and kafirin microparticle film-BMP-2 system in inducing bone growth were determined by a subcutaneous bioassay using a rat model. Kafirin microparticle film and kafirin microparticle film-BMP-2 system was non-irritant to the animals, probably because kafirin is non-allergenic. The kafirin microparticle film implants showed signs of some degradation but a large proportion of these implants was still intact by Day 28 post implantation, probably because of the low susceptibility of kafirin to mammalian proteolytic enzymes. Kafirin microparticle film-BMP-2 system did not induce bone growth, probably mainly due to low BMP-2 dosage and short study duration. Modification of kafirin microparticles by wet heat or glutaraldehyde treatment both result in increased size of the microparticles with similar gross structure. However, it is apparent that with both treatments the proteins within the pre-formed kafirin microparticles undergo some form of further assisted-assembly through different mechanisms. It seems that heat-induced disulphide cross-linking reinforces a layer around the nanostructures, probably rich in γ- kafirin polypeptides, that stabilizes the structure of the nanostructures. In contrast, glutaraldehyde-treatment appears to destabilize this structure-stabilizing layer through formation of γ-kafirin polypeptide-glutaraldehyde covalent bonding. This probably offsets the balance of attractive and repulsive forces between the different kafirin subclasses within the nanostructures, thereby resulting in collapsed nanostructures and linear realignment. A deeper understanding of the mechanism of kafirin self-assembly will be important for further development of kafirin microstructures for different applications. / Thesis (PhD)--University of Pretoria, 2012. / Food Science / unrestricted

Adipositas gehört zu den häufigsten Stoffwechselkrankheiten. Zur Basistherapie der Adipositas gehören eine gesunde Ernährungsweise und die Erhöhung der körperlichen Aktivität mit dem Ziel der Gewichtsreduktion. Körperliches Training führt neben der Verbesserung der Leistungsfähigkeit zu einer Reihe metabolischer Veränderungen, wie zur Reduktion der Fettmasse, zu Verbesserungen von chronischer Hyperglykämie, des Lipidstoffwechsels und des atherogenen, pro-inflammatorischen Adipokin-Serumprofils. Bone morphogenetic proteins (BMPs) werden auch im Fettgewebe produziert und spielen eine wichtige Rolle in der Adipogenese und Transdifferenzierung von Adipozyten. Vor kurzem wurde ein Zusammenhang zwischen der BMP-7 Serumkonzentration und Adipositas postuliert. Allerdings ist bisher nicht bekannt, ob eine Gewichtsreduktion mit Veränderungen der BMP-7 Serumkonzentration assoziiert ist. Ziel dieser Arbeit war es deshalb zu untersuchen, ob die Serumkonzentration von BMP-7 im Zusammenhang mit Körpergewicht, Fettverteilungsmuster, Parametern des Glukosestoffwechsels und der Insulinsensitivität bei Patienten mit Adipositas und Typ 2 Diabetes (n=213) stehen. Im Rahmen von zwei Interventionsstudien mit dem Ziel der Gewichtsreduktion wurde der Einfluss einer hypokalorischen Ernährungsweise mit zusätzlichem körperlichen Training über 6 Monate (n=19) sowie 6 Monaten nach einer bariatrischen Operation (n=14) auf die BMP-7 Serumkonzentration untersucht. Zusätzlich wurde die BMP-7-mRNA Expression im humanen omentalen und subkutanen Fettgewebe von 233 Patienten im Rahmen einer unabhängigen Querschnittstudie charakterisiert. Die BMP-7 Serumkonzentration ist unabhängig von Alter und Geschlecht, korreliert signifikant mit den nüchtern Insulin, C-Peptid und Glukose Serumkonzentrationen, mit der SFRP5-Konzentration bei Probanden ohne Typ2 Diabetes mellitus, signifikant negativ mit den Serumkonzentrationen von Gesamteiweiß, Chemerin, freien Fettsäuren (bei Männern), und DLK-1 (bei Frauen). Bei Patienten mit Typ 2 Diabetes zeigte sich eine negative Korrelation zwischen der BMP-7-Serumkonzentration und ALAT. Die BMP-7 mRNA Expression ist im viszeralen Fettgewebe signifikant höher als im subkutanen Fettgewebe. Sowohl eine moderate Gewichtsreduktion von 8,8±6,5kg [2,0-26,6kg] durch kalorienreduzierte Ernährung als auch ein Gewichtsverlust von 45,3±7,4kg 6 Monate nach bariatrischer Chirurgie führten nicht zu einer signifikanten Veränderung der zirkulierenden BMP-7 Spiegel. Zusammengefasst zeigten die Querschnitts- und Interventionsstudien, dass erhöhte BMP-7- Serumkonzentrationen mit Hyperinsulinämie assoziiert sind, aber durch Gewichtsreduktion und Erhöhung der körperlichen Aktivität nicht signifikant beeinflusst werden können. Die erhöhte BMP-7-Expression im viszeralen Fettgewebe könnte eine intrinsische Besonderheit dieses Fettdepots sein und zur viszeralen Fehlverteilung des Fettgewebes bei Adipositas beitragen.