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Neuroinflammation and brain oxidative stress are recognized as significant contributors to hypertension including salt sensitive hypertension. Extracellular vesicles (EVs) play an essential role in intercellular communication in various situations, including physiological and pathological ones. Based on this evidence, we hypothesized that EVs derived from the brains of hypertensive rats with salt sensitivity could trigger neuroinflammation and oxidative stress during hypertension development. To test this hypothesis, we compared the impact of EVs isolated from the brains of hypertensive Dahl Salt-Sensitive rats (DSS) and normotensive Sprague Dawley (SD) rats on inflammatory factors and mitochondrial reactive oxygen species (mtROS) production in primary neuronal cultures and brain cardiovascular relevant regions, including the hypothalamic paraventricular nucleus (PVN) and lamina terminalis (LT). We found that brain-derived DSS-EVs significantly increased the mRNA levels of proinflammatory cytokines (PICs) and chemokines, including TNFα, IL1ß, CCL2, CCL5, and CCL12, as well as the transcriptional factor NF-κB in neuronal cultures. DSS-EVs also induced oxidative stress in neuronal cultures, as evidenced by elevated NADPH oxidase subunit CYBA coding gene mRNA levels and persistent mtROS elevation. When DSS-EVs were injected into the brains of normal SD rats, the mRNA levels of PICs, chemokines, and the chronic neuronal activity marker FOSL1 were significantly increased in the PVN and LT. Furthermore, DSS-EVs caused mtROS elevation in brain PVN and LT, particularly in neurons. Our study reveals a novel role for brain-derived EVs from hypertensive rats in triggering neuroinflammation, upregulating chemokine expression, and inducing excessive ROS production. These findings provide insight into the complex interactions between EVs and hypertension-associated processes, offering potential therapeutic targets for hypertension-linked neurological complications.
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Conductive biohybrid cell-material systems have applications in bioelectronics and biorobotics. To date, conductive scaffolds are limited to those with low electrical conductivity or 2D sheets. Here, 3D biohybrid conductive systems are developed using fibroblasts or cardiomyocytes integrated with carbon nanotube (CNT) forests that are densified due to interactions with a gelatin coating. CNT forest scaffolds with a height range of 120-240 µm and an average electrical conductivity of 0.6 S/cm are developed and shown to be cytocompatible as evidenced from greater than 89% viability measured by live-dead assay on both cells on day 1. The cells spread on top and along the height of the CNT forest scaffolds. Finally, the scaffolds have no adverse effects on the expression of genes related to cardiomyocyte maturation and functionality, or fibroblast migration, adhesion, and spreading. The results show that the scaffold could be used in applications ranging from organ-on-a-chip systems to muscle actuators.
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Conducting in vivo brain imaging can be a challenging task due to the complexity of brain tissue and the strict requirements for safe and effective imaging agents. However, a new fluorescent dye called Cy5-PEG2 has been developed that selectively accumulates in mitochondria, enabling the visualization of these essential organelles in various cell lines. This dye is versatile and can be used for the real-time monitoring of mitochondrial dynamics in living cells. Moreover, it can cross the blood-brain barrier, making it a promising tool for noninvasive in vivo brain imaging. Based on the assessment of glial cell responses in the hippocampus and neocortex regions using GFAP and Iba1 biomarkers, Cy5-PEG2 seems to have minimal adverse effects on brain immune response or neuronal health. Therefore, this mitochondria-targeting fluorescent dye has the potential to advance our understanding of mitochondrial dynamics and function within the broader context of whole-brain physiology and disease progression. However, further research is needed to evaluate the safety and efficacy of Cy5-PEG2.
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Mitochondrial dysfunction is implicated in both brain tumors and neurodegenerative diseases, leading to various cellular abnormalities that can promote tumor growth and resistance to thera-pies, as well as impaired energy production and compromised neuronal function. Developing targeted therapies aimed at restoring mitochondrial function and improving overall cellular health could potentially be a promising approach to treating these conditions. Brain-derived exosomes (BR-EVs) have emerged as potential drug delivery vessels for neurological conditions. Herein, we report a new method for creating mitochondria-targeting exosomes and test its application in vitro and in vivo.
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Mitochondrial dysfunction is associated with various health conditions, including cardiovascular and neurodegenerative diseases. Mitochondrial-targeting therapy aims to restore or enhance mitochondrial function to treat or alleviate these conditions. Exosomes, small vesicles that cells secrete, containing a variety of biomolecules, are critical in cell-to-cell communication and have been studied as potential therapeutic agents. Exosome-based therapy has the potential to treat both cardiovascular and neurodegenerative diseases. Combining these two approaches involves using exosomes as carriers to transport mitochondrial-targeting agents to dysfunctional or damaged mitochondria within target cells. This article presents a new technique for engineering brain-derived exosomes that target mitochondria and has demonstrated promise in initial tests with primary neuron cells and healthy rats. This promising development represents a significant step forward in treating these debilitating conditions.
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Abnormal microRNA functions are closely associated with pancreatic ß-cell loss and dysfunction in type 2 diabetes. Dysregulation of miR-30d has been reported in the individuals with diabetes. To study how miR-30d affects pancreatic ß-cell functions, we generated two transgenic mouse lines that specifically overexpressed miR-30d in ß-cells at distinct low and high levels. Transgenic overexpressed miR-30d systemically affected ß-cell function. Elevated miR-30d at low-level (TgL, 2-fold) had mild effects on signaling pathways and displayed no significant changes to metabolic homeostasis. In contrast, transgenic mice with high-level of miR-30d expression (TgH, 12-fold) exhibited significant diet-induced hyperglycemia and ß-cell dysfunction. In addition, loss of ß-cell identity was invariably accompanied with increased insulin/glucagon-double positive bihormonal cells and excess plasma glucagon levels. The transcriptomic analysis revealed that miR-30d overexpression inhibited ß-cell-enriched gene expression and induced α-cell-enriched gene expression. These findings implicate that an appropriate miR-30d level is essential in maintaining normal ß-cell identity and function.
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Diabetes Mellitus Tipo 2 , Células Secretoras de Glucagon , Células Secretoras de Insulina , MicroRNAs , Animais , Diabetes Mellitus Tipo 2/genética , Diabetes Mellitus Tipo 2/metabolismo , Glucagon/metabolismo , Células Secretoras de Glucagon/metabolismo , Células Secretoras de Insulina/metabolismo , Camundongos , MicroRNAs/metabolismoRESUMO
Direct atomic-scale observation of the local phase transition in transition metal dichalcogenides (TMDCs) is critically required to carry out in-depth studies of their atomic structures and electronic features. However, the structural aspects including crystal symmetries tend to be unclear and unintuitive in real-time monitoring of the phase transition process. Herein, by using in situ transmission electron microscopy, information about the phase transition mechanism of MoTe2 from hexagonal structure (2H phase) to monoclinic structure (1T' phase) driven by sublimation of Te atoms after a spike annealing is obtained directly. Furthermore, with the control of Te atom sublimation by modulating the hexagonal boron nitride (h-BN) coverage in the desired area, the lateral 1T'-enriched MoTe2 /2H MoTe2 homojunction can be one-step constructed via an annealing treatment. Owing to the gradient bandgap provided by 1T'-enriched MoTe2 and 2H MoTe2 , the photodetector composed of the 1T'-enriched MoTe2 /2H MoTe2 homojunction shows fast photoresponse and ten times larger photocurrents than that consisting of a pure 2H MoTe2 channel. The study reveals a route to improve the performance of optoelectronic and electronic devices based on TMDCs with both semiconducting and semimetallic phases.
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Alzheimer's disease (AD) is the most common age-associated dementia with complex pathological hallmarks. Mitochondrion, synaptosome, and myelin sheath appear to be vulnerable and play a key role in the pathogenesis of AD. To clarify the early mechanism associated with AD, followed by subcellular components separation, we performed iTRAQ (isobaric tags for relative and absolute quantification)-based proteomics analysis to simultaneously investigate the differentially expressed proteins (DEPs) within the mitochondria, synaptosome, and myelin sheath in the cerebrum of the 6-month-old triple transgenic AD (3 × Tg-AD) and 6-month-old wild-type (WT) mice. A large number of DEPs between the AD and WT mice were identified. Most of them are related to mitochondria and synaptic dysfunction and cytoskeletal protein change. Differential expressions of Lrpprc, Nefl, and Sirpa were verified by Western blot analysis. The results suggest that decreased energy metabolism, impaired amino acid metabolism and neurotransmitter synthesis, increase compensatory fatty acid metabolism, up-regulated cytoskeletal protein expression, and oxidative stress are the early events of AD. Among these, mitochondrial damage, synaptic dysfunction, decreased energy metabolism, and abnormal amino acid metabolism are the most significant events. The results indicate that it is feasible to separate and simultaneously perform proteomics analysis on the three subcellular components.
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Doença de Alzheimer , Cérebro , Doença de Alzheimer/patologia , Aminoácidos/metabolismo , Animais , Cérebro/metabolismo , Cérebro/patologia , Proteínas do Citoesqueleto/metabolismo , Modelos Animais de Doenças , Camundongos , Camundongos Transgênicos , Mitocôndrias/metabolismo , Bainha de Mielina/metabolismo , Proteômica/métodos , Sinaptossomos/metabolismoRESUMO
INTRODUCTION: Gestational diabetes mellitus (GDM) is a common complication during pregnancy. Looking for reliable diagnostic markers for early diagnosis can reduce the impact of the disease on the fetus OBJECTIVE: The present study is designed to find plasma metabolites that can be used as potential biomarkers for GDM, and to clarify GDM-related mechanisms METHODS: By non-target metabolomics analysis, compared with their respective controls, the plasma metabolites of GDM pregnant women at 12-16 weeks and 24-28 weeks of pregnancy were analyzed. Multiple reaction monitoring (MRM) analysis was performed to verify the potential marker RESULTS: One hundred and seventy-two (172) and 478 metabolites were identified as differential metabolites in the plasma of GDM pregnant women at 12-16 weeks and 24-28 weeks of pregnancy, respectively. Among these, 40 metabolites were overlapped. Most of them are associated with the mechanism of diabetes, and related to short-term and long-term complications in the perinatal period. Among them, 7 and 10 differential metabolites may serve as potential biomarkers at the 12-16 weeks and 24-28 weeks of pregnancy, respectively. By MRM analysis, compared with controls, increased levels of 17(S)-HDoHE and sebacic acid may serve as early prediction biomarkers of GDM. At 24-28 weeks of pregnancy, elevated levels of 17(S)-HDoHE and L-Serine may be used as auxiliary diagnostic markers for GDM CONCLUSION: Abnormal amino acid metabolism and lipid metabolism in patients with GDM may be related to GDM pathogenesis. Several differential metabolites identified in this study may serve as potential biomarkers for GDM prediction and diagnosis.
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Diabetes Gestacional , Biomarcadores , Diabetes Gestacional/diagnóstico , Feminino , Humanos , Metabolismo dos Lipídeos , Metabolômica , Gravidez , GestantesRESUMO
Pancreatic ß-cell dysfunction is central to the development and progression of type 2 diabetes. Dysregulation of microRNAs (miRNAs) has been associated with pancreatic islet dysfunction in type 2 diabetes. Previous study has shown that miR-483 is expressed relatively higher in ß-cells than in α-cells. To explore the physiological function of miR-483, we generated a ß-cell-specific knockout mouse model of miR-483. Loss of miR-483 enhances high-fat diet-induced hyperglycemia and glucose intolerance by the attenuation of diet-induced insulin release. Intriguingly, mice with miR-483 deletion exhibited loss of ß-cell features, as indicated by elevated expression of aldehyde dehydrogenase family 1, subfamily A3 (Aldh1a3), a marker of ß-cell dedifferentiation. Moreover, Aldh1a3 was validated as a direct target of miR-483 and overexpression of miR-483 repressed Aldh1a3 expression. Genetic ablation of miR-483 also induced alterations in blood lipid profile. Collectively, these data suggest that miR-483 is critical in protecting ß-cell function by repressing the ß-cell disallowed gene Aldh1a3. The dysregulated miR-483 may impair insulin secretion and initiate ß-cell dedifferentiation during the development of type 2 diabetes.
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Diabetes Mellitus Tipo 2/genética , Células Secretoras de Insulina/metabolismo , MicroRNAs/genética , Retinal Desidrogenase/genética , Animais , Diferenciação Celular , Diabetes Mellitus Tipo 2/enzimologia , Diabetes Mellitus Tipo 2/metabolismo , Diabetes Mellitus Tipo 2/fisiopatologia , Humanos , Insulina/metabolismo , Secreção de Insulina , Células Secretoras de Insulina/citologia , Masculino , Camundongos , Camundongos Knockout , MicroRNAs/metabolismo , Retinal Desidrogenase/metabolismoRESUMO
PURPOSE: This study is designed to screen serum proteins that may serve as biomarkers for gestational diabetes mellitus (GDM), and clarify the mechanisms of disease. EXPERIMENTAL DESIGN: By using isobaric tags for relative and absolute quantitation proteomics analysis, serum proteins levels were quantified in pregnant women who subsequently developed GDM (12-16 weeks), GDM patients (24-28 weeks), and their corresponding controls. The strategy of mixing samples is used in proteomic analysis. RESULTS: Thirty-one and 27 differentially expressed proteins are identified in the serum of pregnant women with developed GDM at 12-16 weeks and GDM patients during 24-28 weeks, respectively. Thirty eight and 28 proteins are identified in 24-28 weeks versus 12-16 weeks controls (24/12 CTR group), and 24-28 weeks GDM patients versus 12-16 weeks women with subsequently developed GDM (24/12 GDM group), respectively. Most of these proteins in the case and control subjects are associated with diabetes and maternal and perinatal short- and long-term complications. CONCLUSIONS AND CLINICAL RELEVANCE: The results highlight the roles of complement system and the blood clotting cascade in the pathogenesis of GDM. Differentially expressed proteins may serve as potential biomarkers for GDM prediction and diagnosis in the future.
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Proteínas Sanguíneas/metabolismo , Diabetes Gestacional/sangue , Diabetes Gestacional/metabolismo , Trimestres da Gravidez/sangue , Proteômica , Adulto , Biomarcadores/sangue , Biomarcadores/metabolismo , Feminino , Perfilação da Expressão Gênica , Humanos , Gravidez , Trimestres da Gravidez/metabolismo , Mapas de Interação de ProteínasRESUMO
Autism is one of the most common neurological developmental disorder associated with social isolation and restricted interests in children. The etiology of this disorder is still unknown. There is neither any confirmed laboratory test nor any effective therapeutic strategy to diagnose or cure it. To search for biomarkers for early detection and exploration of the disease mechanisms, here, we investigated the protein expression signatures of peripheral blood mononuclear cells (PBMCs) in autistic children compared with healthy controls by using isobaric tags for relative and absolute quantitation (iTRAQ) proteomics approach. The results showed a total of 41 proteins as differentially expressed in autistic group as compared to control. These proteins are found associated with metabolic pathways, endoplasmic reticulum (ER) stress and protein folding, endocytosis, immune and inflammatory response, plasma lipoprotein particle organization, and cell adhesion. Among these, 17 proteins (13 up-regulated and four down-regulated) are found to be linked with mitochondria. Eight proteins including three already reported proteins in our previous studies were selected to be verified. Five already reported autism associated pro-inflammatory cytokines [interferon-γ (IFN-γ), interleukin-1ß (IL-1ß), IL-6, IL-12, and tumor necrosis factor-α (TNF-α)] were detected in plasma by enzyme-linked immunosorbent assay (ELISA) analysis. The results were consistent with proteomic results and reports from previous literature. These results proposed that PBMCs from autistic children might be activated, and ER stress, unfolded protein response (UPR), acute-phase response (APR), inflammatory response, and endocytosis may be involved in autism occurrence. These reported proteins may serve as potential biomarkers for early diagnosis of autism. More specifically, simultaneous detection of three proteins [complement C3 (C3), calreticulin (CALR), and SERPINA1] in the plasma and PBMCs could increase the authenticity of detection.
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We previously showed different effects of tobacco and nicotine on fracture healing, but due to pump reservoir limits, maximum exposure period was 4 weeks. To allow flexibility in pre- and post-fracture exposure periods, the objective of this study was to compare a new oral administration route for nicotine to the established pump method. Four groups were studied: (1) pump saline, (2) pump saline + oral tobacco, (3) pump saline/nicotine + oral tobacco, and (4) pump saline + oral nicotine/tobacco. Sprague-Dawley rats (n = 84) received a transverse femoral fracture stabilized with an intramedullary pin 1 week after initiating dosing. After 3 weeks, no difference was found in torsional strength or stiffness between oral nicotine/tobacco or pump nicotine + tobacco, while energy absorption with oral nicotine/tobacco was greater than pump nicotine + tobacco (p < 0.05). Compared to saline control, strength for oral nicotine/tobacco was higher than control (p < 0.05), and stiffnesses for pump nicotine + tobacco and oral nicotine/tobacco were higher than control (p < 0.05). No differences in energy were found for either nicotine-tobacco group compared to saline control. Mean serum cotinine (stable nicotine metabolite) was different between pump and oral nicotine at 1 and 4 weeks, but all groups were in the range of 1-2 pack/day smokers. In summary, relevant serum cotinine levels can be reached in rats with oral nicotine, and, in the presence of tobacco, nicotine can influence mechanical aspects of fracture healing, dependent on administration method. Caution should be exercised when comparing results of fracture healing studies using different methods of nicotine administration.
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Consolidação da Fratura/efeitos dos fármacos , Fraturas Fechadas/fisiopatologia , Nicotiana , Nicotina/farmacologia , Extratos Vegetais/farmacologia , Administração Oral , Animais , Modelos Animais de Doenças , Sistemas de Liberação de Medicamentos , Fraturas Fechadas/diagnóstico por imagem , Bombas de Infusão , Masculino , Agonistas Nicotínicos/farmacologia , Radiografia , Ratos , Ratos Sprague-Dawley , Torção Mecânica , ÁguaRESUMO
Revision joint replacement has poorer outcomes that have been associated with poorer mechanical fixation. We investigate a new bone-sparing surgical technique that locally cracks the sclerotic bone rim formed during aseptic loosening. We inserted 16 hydroxyapatite-coated implants bilaterally in the distal femur of eight dogs, using a controlled weight-bearing experimental model that replicates important features of a typical revision setting. At 8 weeks, a control revision procedure and a crack revision procedure were performed on contralateral implants. The crack procedure used a splined tool to perform a systematic local perforation of the sclerotic bone rim of the revision cavity. After 4 weeks, the hydroxyapatite-coated implants were evaluated for mechanical fixation by a push-out test and for tissue distribution by histomorphometry. The cracking revision procedure resulted in significantly improved mechanical fixation, significantly more bone ongrowth and bone volume in the gap, and reduced fibrous tissue compared to the control revision procedure. The study demonstrates that the sclerotic bone rim prevents bone ingrowth and promotes fixation by fibrous tissue. The effect of the cracking technique may be due to improved access to the vascular compartment of the bone. The cracking technique is a simple surgical method that potentially can improve the fixation of revision implants in sclerotic regions important for obtaining the fixation critical for overall implant stability.
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Artroplastia do Joelho/métodos , Reoperação/métodos , Animais , Osso e Ossos/cirurgia , Materiais Revestidos Biocompatíveis , Cães , Durapatita , Feminino , Fêmur/patologia , Membro Posterior , Próteses e Implantes , EscleroseRESUMO
Type I diabetes mellitus inhibits fracture healing and leads to an increase in complications. As a pilot study, we used a closed fracture model in the diabetic rat to address the question of whether osteogenic protein-1 (OP-1) in a collagen carrier can overcome this inhibition by increasing the area of the newly mineralized callus and femoral torque to failure compared with diabetic animals with fractures treated without OP-1. Diabetes was created in 54 rats by injection of streptozotocin. After 2 weeks, a closed femur fracture was created using a drop-weight impaction device. Each fracture site was immediately opened and treated with or without 25 microg OP-1 in a collagen carrier. Animals were euthanized after 2 or 4 weeks. Fracture healing was assessed by callus area from high-resolution radiographs, callus strength from torsional failure testing, and undecalcified histologic analysis. The area of newly mineralized callus was greater in diabetic animals treated with 25 microg OP-1/carrier compared with diabetic animals with untreated fractures and with fractures treated with carrier alone. This increase in callus area did not translate into an equivalent increase in torque to failure. Osteogenic protein-1 showed some evidence of overcoming the inhibition of fracture healing in the diabetic rat.
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Proteína Morfogenética Óssea 7/administração & dosagem , Diabetes Mellitus Experimental/complicações , Diabetes Mellitus Tipo 1/complicações , Fraturas do Fêmur/tratamento farmacológico , Consolidação da Fratura/efeitos dos fármacos , Fraturas Fechadas/tratamento farmacológico , Animais , Fenômenos Biomecânicos , Calo Ósseo/efeitos dos fármacos , Calo Ósseo/fisiopatologia , Calcificação Fisiológica/efeitos dos fármacos , Colágeno Tipo I , Diabetes Mellitus Experimental/diagnóstico por imagem , Diabetes Mellitus Experimental/tratamento farmacológico , Diabetes Mellitus Experimental/fisiopatologia , Diabetes Mellitus Tipo 1/diagnóstico por imagem , Diabetes Mellitus Tipo 1/tratamento farmacológico , Diabetes Mellitus Tipo 1/fisiopatologia , Portadores de Fármacos , Fraturas do Fêmur/complicações , Fraturas do Fêmur/diagnóstico por imagem , Fraturas do Fêmur/fisiopatologia , Fraturas Fechadas/complicações , Fraturas Fechadas/diagnóstico por imagem , Fraturas Fechadas/fisiopatologia , Masculino , Projetos Piloto , Radiografia , Ratos , Ratos Sprague-Dawley , Fatores de Tempo , TorqueRESUMO
The osteoinductive capability of BMPs appears diminished in the setting of acute infection. We applied rhBMP-2 to a segmental defect in a rat femur and measured the expression of key bone formation genes in the presence of acute infection. Types I and II collagen, osteocalcin, and BMP Type II receptor mRNA expression were characterized in 72 Sprague-Dawley rats, which received either bovine collagen carrier with 200 mug rhBMP-2 plus Staphylococcus aureus, carrier with bacteria only, carrier with rhBMP-2 only, or carrier alone. Six animals from each group were euthanized at 1, 2, and 4 weeks. Total RNA was isolated and extracted, and mRNA was determined by real-time comparative quantitative PCR. Infected defects had little expression of collagen I and II and osteocalcin mRNAs, while BMP receptor II expression with infection was greater than carrier-only controls at weeks 2 and 4. Notably, all four genes were upregulated in infected defects in the presence of rhBMP-2. Thus, in a clinical setting with a high risk of infection and nonunion, such as a compound fracture with bone loss, rhBMP-2 may increase the rate and extent of bone formation. Even if infection does occur, rhBMP-2 may allow a quicker overall recovery time.
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Doenças Ósseas Infecciosas/tratamento farmacológico , Proteína Morfogenética Óssea 2/administração & dosagem , Remodelação Óssea/efeitos dos fármacos , Fraturas do Fêmur/tratamento farmacológico , Fêmur/efeitos dos fármacos , Consolidação da Fratura/efeitos dos fármacos , Infecções Estafilocócicas/tratamento farmacológico , Animais , Doenças Ósseas Infecciosas/genética , Doenças Ósseas Infecciosas/microbiologia , Doenças Ósseas Infecciosas/fisiopatologia , Receptores de Proteínas Morfogenéticas Ósseas Tipo II/genética , Remodelação Óssea/genética , Colágeno Tipo I/genética , Colágeno Tipo II/genética , Modelos Animais de Doenças , Portadores de Fármacos , Fraturas do Fêmur/genética , Fraturas do Fêmur/microbiologia , Fraturas do Fêmur/fisiopatologia , Fêmur/metabolismo , Fêmur/microbiologia , Fêmur/cirurgia , Consolidação da Fratura/genética , Humanos , Osteocalcina/genética , RNA Mensageiro/metabolismo , Ratos , Ratos Sprague-Dawley , Proteínas Recombinantes/administração & dosagem , Infecções Estafilocócicas/genética , Infecções Estafilocócicas/microbiologia , Infecções Estafilocócicas/fisiopatologia , Staphylococcus aureus/patogenicidade , Tampões de Gaze Cirúrgicos , Fatores de Tempo , Regulação para CimaRESUMO
BACKGROUND AND PURPOSE: We studied whether osseointegration and fixation of plasma-sprayed titanium implants grafted with beta-TCP granules (Ossaplast) can be improved by adding an osteogenic signal (Colloss E). The results were compared to implants grafted with fresh frozen morselized allograft with and without the Colloss E device. METHODS: 4 porous-coated Ti implants were placed in the proximal humeri in each of 10 dogs. All implants were surrounded by a 2.5-mm defect, which was grafted with: (A) beta-TCP, (B) beta-TCP+20 mg Colloss E, (C) allograft, or (D) allograft+20 mg Colloss E. The observation time was 4 weeks. RESULTS: Mechanical testing showed that the beta-TCP group with Colloss E was twice as well fixed as the control group grafted with beta-TCP granules alone, and comparable to both allograft groups. We found that every control implant in the beta-TCP grafted group was covered by a dense fibrous membrane. No fibrous tissue was seen in the beta-TCP group augmented with Colloss. These implants were well osseointegrated, with new bone covering 10-25% of the implant surface. Both treated groups had increased graft resorption compared to their respective control groups. Colloss E had no effect on new bone formation or fibrous tissue reduction around the allografted implants. INTERPRETATION: The Colloss E device improved early osseointegration of implants grafted with beta-TCP granules and increased their mechanical implant fixation to the level of allografted implants. The experiment indicates that ceramic bone substitutes may be a viable alternative to allograft when combined with an osteogenic signal such as Colloss E.
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Substitutos Ósseos , Transplante Ósseo , Implantes Experimentais , Animais , Transplante Ósseo/métodos , Cerâmica , Cães , Úmero/patologia , Úmero/fisiologia , Osseointegração/fisiologia , Estresse Mecânico , Titânio , Transplante HomólogoRESUMO
OBJECTIVES: The goal of this study was to determine whether recombinant human bone morphogenetic protein-2 (rhBMP-2) would induce new bone formation in an internally stabilized segmental defect with a chronic bacterial infection in the rat femur and whether treatment with systemic antibiotic would enhance this effect. METHODS: A 6-mm unilateral femoral segmental defect was surgically created in 120 Sprague-Dawley rats, internally stabilized with a polyacetyl plate and 6 Kirschner wires, and contaminated with 10(4) colony-forming units of Staphylococcus aureus. After 2 weeks, all defects were surgically debrided and implanted with 0, 20, or 200 microg of rhBMP-2 in a type 1 bovine collagen sponge. Half of the animals in each treatment group received 4 weeks of systemic antibiotic, and half did not. Animals were euthanized at 4 or 12 weeks after debridement. Bone formation within and adjacent to the defect was assessed using microcomputed tomography, torsional failure testing and undecalcified histology. RESULTS: No substantial callus formed in the infected defects without rhBMP-2. Significantly more mineralized callus was induced with the higher dose of rhBMP-2 than with the lower dose (P = 0.001), with systemic antibiotic therapy than without (P < 0.001), and at 12 weeks after debridement compared with 4 weeks (P < 0.001). CONCLUSIONS: Recombinant human bone morphogenetic protein-2 maintained its osteoinductive capability in the presence of a chronic infection, and this property was enhanced by systemic antibiotic. This study presents an intervention that may potentially accelerate fracture healing in the presence of infection and colonized hardware, thereby permitting earlier removal of the hardware, and more timely and effective treatment of infection.
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Antibacterianos/administração & dosagem , Proteínas Morfogenéticas Ósseas/administração & dosagem , Ceftriaxona/administração & dosagem , Desbridamento/métodos , Fêmur , Osteomielite/terapia , Proteínas Recombinantes/administração & dosagem , Infecções Estafilocócicas/terapia , Fator de Crescimento Transformador beta/administração & dosagem , Animais , Proteína Morfogenética Óssea 2 , Regeneração Óssea/efeitos dos fármacos , Modelos Animais de Doenças , Implantes de Medicamento , Quimioterapia Combinada , Seguimentos , Injeções Intramusculares , Osteomielite/diagnóstico por imagem , Osteomielite/patologia , Ratos , Ratos Sprague-Dawley , Infecções Estafilocócicas/diagnóstico por imagem , Infecções Estafilocócicas/patologia , Tomografia Computadorizada por Raios X , Resultado do TratamentoRESUMO
Bone resorption associated with local trauma occurring during insertion of joint prostheses is recognized as an early event. Being an osteoclastic inhibitor, alendronate is a potential candidate means to decrease early periprosthetic bone resorption and thereby improve implant fixation. We investigated the influence of oral alendronate treatment on early implant fixation in two implant interface settings representing sites of an implant that are in contact with surrounding bone, and other sites without intimate bone contact. One plasma-sprayed cylindrical titanium implant (6 mm diameter) was inserted into each proximal tibia of 16 dogs. On one side the implant was inserted press-fit whereas on the contralateral side, the implants were surrounded by a 2 mm concentric gap. Oral alendronate (0.5 mg/kg/day) was given 2 weeks following surgery to eight dogs. The dogs were euthanized after 10 weeks of alendronate treatment. Bone ongrowth (bone in contact with implant surface) was estimated using the linear intercept technique and shear strength was calculated as the slope on a load-displacement curve. For the press fit implants, alendronate treatment significantly increased bone ongrowth from 24% to 29% and significantly increased ultimate shear strength from 1.26 to 3.72 MPa. Also, the fraction of periprosthetic bone significantly increased from 10% to 18%. For implants surrounded by a gap, alendronate neither stimulated nor impaired implant fixation, bone ingrowth, or new bone formation in the gaps. Because early implant stability is an important predictor of longevity, systemic alendronate treatment could be an important clinical tool to positively influence the early stages of implant incorporation.