Search results for "Bones"
showing 10 items of 279 documents
Comparison of two different lingual flap advancement techniques and vascular structure identification: a human cadaver study.
2022
Background: One of the most frequent complications in guided bone regeneration (GBR) is wound dehiscence, which compromises treatment outcomes. Thus, primary tension-free suture is essential to avoid wound dehiscence. The purpose of this study was to compare the extension of 2 different mandibular flaps in human cadaveric specimens, and to measure the size of the supraperiosteal blood vessels. Material and methods: Five freshly unfrozen human cadaveric specimens were used. Arteries and veins were marked and bilateral classical lingual flaps (extending from the second premolar to the retromolar area) were prepared. In one side, the mylohyoid muscle was detached to increase the coronal extens…
Macrophage-mediated angiogenic activation of outgrowth endothelial cells in co-culture with primary osteoblasts.
2014
The successful vascularisation of complex tissue engineered constructs for bone regeneration is still a major challenge in the field of tissue engineering. In this context, co-culture systems of endothelial cells and osteoblasts represent a promising approach to advance the formation of a stable vasculature as well as an excellent in vitro model to identify factors that positively influence bone healing processes, including angiogenesis. Under physiological conditions, the activation phase of angiogenesis is mainly induced by hypoxia or inflammation. Inflammatory cells such as macrophages secrete proinflammatory cytokines and proangiogenic growth factors, finally leading to the formation of…
Distribution of Cartilage Proteoglycan (Aggrecan) Core Protein and Link Protein Gene Expression during Human Skeletal Development
1991
The distribution of cartilage proteoglycan core protein (aggrecan) and cartilage proteoglycan link protein was investigated by in situ hybridization during different stages of human skeletal development. Aggrecan and link protein expression were confined to chondrocytes of the developing skeleton and other cartilaginous structures. Distribution and intensity of the signal was identical with aggrecan as compared to link protein probes. Parallel to the calcification of cartilaginous matrix, chondrocytes of this area lost the expression of aggrecan and link protein specific mRNA and stayed negative throughout the following stages of skeletal development. Highest expression was found in the low…
Preliminary analysis of osteocyte lacunar density in long bones of tetrapods: all measures are bigger in sauropod dinosaurs.
2013
Osteocytes harbour much potential for paleobiological studies. Synchrotron radiation and spectroscopic analyses are providing fascinating data on osteocyte density, size and orientation in fossil taxa. However, such studies may be costly and time consuming. Here we describe an uncomplicated and inexpensive method to measure osteocyte lacunar densities in bone thin sections. We report on cell lacunar densities in the long bones of various extant and extinct tetrapods, with a focus on sauropodomorph dinosaurs, and how lacunar densities can help us understand bone formation rates in the iconic sauropod dinosaurs. Ordinary least square and phylogenetic generalized least square regressions sugge…
Cathepsin L in metastatic bone disease: therapeutic implications
2010
AbstractCathepsin L is a lysosomal cysteine proteinase primarily devoted to the metabolic turnover of intracellular proteins. However, accumulating evidence suggests that this endopeptidase might also be implicated in the regulation of other important biological functions, including bone resorption in normal and pathological conditions. These findings support the concept that cathepsin L, in concert with other proteolytic enzymes involved in bone remodeling processes, could contribute to facilitate bone metastasis formation. In support of this hypothesis, recent studies indicate that cathepsin L can foster this process by triggering multiple mechanisms which, in part, differ from those of t…
Quantitative ultrasound predicts bone mineral density and failure load in human lumbar vertebrae
2006
Quantitative ultrasound is in widespread clinical use for assessment of bone quality at peripheral skeletal sites, but has not yet been applied to those sites in the axial skeleton, such as the spine and hip, where osteoporotic fractures are common.Ultrasound measurements were made in 11 cadaveric vertebrae and relationships with bone mineral density and failure load were investigated. An ultrasonic imaging system was used to measure speed of sound, broadband ultrasonic attenuation, and attenuation at a single frequency, through the vertebral body in the sagittal plane. Ultrasonic measurements were averaged over a region of interest centrally within the vertebral body, and were calculated w…
Do More Highly Organized Collagen Fibrils Increase Bone Mechanical Strength in Loss of Mineral Density After One-Year Running Training?
1999
The aim of this study was to evaluate the effects of long-term running training on the structural properties of bone. Ten beagle dogs ran according to a strenuous progressive program (up to 40 km/day) for 1 year. At the end of the training program, there was a significant reduction in bone mineral density (up to 9.7%) in the vertebrae of the runner dogs as compared with 10 sedentary control dogs. Polarized light microscopy of the vertebral trabecular bone, however, displayed proportionally higher retardation values of the collagen network of the runner dogs than of the sedentary dogs, suggesting a reorganization in a more parallel manner in the collagen fibrils. The concentration and cross-…
Zur erweitrten Indikationsstellung der Herbert-Schrauben-Osteosynthese
1995
Since 1984 the typical headless double threaded Herbert/Whipple screw is known in managing scaphoid fractures and scaphoid non-unions. We resume technical, biomechanical and histological aspects to point out advantages and disadvantages of this osteosynthesis. Our case review of 39 patients illustrate the same good results as achieved in treating scaphoid injuries, when using the Herbert/Whipple screw of a larger diameter for expanded indications other than scaphoid fractures, such as humeral- or radial-head fractures, Jones fractures and others.
Amplified morphogenetic and bone forming activity of amorphous versus crystalline calcium phosphate/polyphosphate.
2020
Amorphous Ca-phosphate (ACP) particles stabilized by inorganic polyphosphate (polyP) were prepared by co-precipitation of calcium and phosphate in the presence of polyP (15% [w/w]). These hybrid nanoparticles showed no signs of crystallinity according to X-ray diffraction analysis, in contrast to the particles obtained at a lower (5% [w/w]) polyP concentration or to hydroxyapatite. The ACP/15% polyP particles proved to be a suitable matrix for cell growth and attachment and showed pronounced osteoblastic and vasculogenic activity in vitro. They strongly stimulated mineralization of the human osteosarcoma cell line SaOS-2, as well as cell migration/microvascularization, as demonstrated in th…
Histomorphological study of the bone regeneration capacity of platelet-rich plasma, bone marrow and tricalcium phosphate Experimental study on pigs
2009
Introduction: Bone defects are rather common after oral surgery and may prove difficult to repair. Objective: We provide a histomorphological analysis of the bone regenerative capacity of platelet-rich plasma at different concentrations and the extraction of platelet-rich bone marrow, compared with -tricalcium phosphate. Methodology: We performed an experimental study on 8 pigs, in which we performed trepanations of the mandible in order to place the materials to be studied. Using an electron microscope, we observed the samples obtained and took a series of photographs in order to analyze the samples through a gray-scale histogram system. Results: Ossification phenomena were present in 96% …