1,720,986 research outputs found
Osteocyte apoptosis and absence of bone remodeling in human auditory ossicles and scleral ossicles of lower vertebrates: a mere coincidence or linked processes?
No full textConsidering the pivotal role as bone mechanosensors ascribed to osteocytes in bone adaptation to mechanical strains, the present study analyzed whether a correlation exists between osteocyte apoptosis and bone remodeling in peculiar bones, such as human auditory ossicles and scleral ossicles of lower vertebrates, which have been shown to undergo substantial osteocyte death and trivial or no bone turnover after cessation of growth. The investigation was performed with a morphological approach under LM (by means of an in situ end-labeling technique) and TEM. The results show that a large amount of osteocyte apoptosis takes place in both auditory and scleral ossicles after they reach their final size. Additionally, no morphological signs of bone remodeling were observed. These facts suggest that (1) bone remodeling is not necessarily triggered by osteocyte death, at least in these ossicles, and (2) bone remodeling does not need to mechanically adapt auditory and scleral ossicles since they appear to be continuously submitted to stereotyped stresses and strains; on the contrary, during the resorption phase, bone remodeling might severely impair the mechanical resistance of extremely small bony segments. Thus, osteocyte apoptosis could represent a programmed process devoted to make stable, when needed, bone structure and mechanical resistance
Subclinical inflammation of colorectal mucosa is related to systemic oxidative balance in healthy adult subjects
No full textOxidative balance is related to myeloperroxidase-positive cell count in normal colorectal mucos
Static and dynamic bone formation and the mechanism of collagen fiber orientation.
No full textWoven bone forms by FBS, whereas the deposition of a bone tissue with orderly arranged collagen fibers (parallel-fibered and lamellar bone) may only occur by DBF, i.e. by movable osteoblasts
TUNEL REVEALS THE ONSET OF APOPTOSIS ON MESENCHYMAL CELLS IN STATIC AND DYNAMIC BONE FORMATION.
No full textApoptosis is mostly associated with DBF with respect SBF during intramembranous ossification
Immunocytochemical and structural comparative study of committed versus multipotent stem cells cultured with different biomaterials
No full textThe aim of this work was the comparison of the behavior of committed (human osteoblast cells - hOB - from bone biopsies) versus multipotent (human dental pulp stem cells - hDPSC - from extracted teeth) cells, cultured on shot-peened titanium surfaces, since the kind of cell model considered has been shown to be relevant in techniques widely used in studies on composition/morphology of biomaterial surfaces. The titanium surface morphology, with different roughness, and the behavior of cells were analyzed by confocal microscope (CM), scanning electron microscope (SEM) and X-ray microanalysis. The best results, in terms of hOB adhesion/distribution, were highlighted by both CM and SEM in cultured plates having 20-mum-depth cavities. On the contrary, CM and SEM results highlighted the hDPSC growth regardless the different surface morphology, arranged in overlapped layers due to their high proliferation rate, showing their unfitness in biomaterial surface test. Nevertheless, hDPSC cultured inside 3D-matrices reproduced an osteocyte-like three-dimensional network, potentially useful in the repair of critical size bone defects. The behavior of the two cell models suggests a different use in biomaterial cell cultures: committed osteoblast cells could be appropriate in selecting the best surfaces to improve osseointegration, while multipotent cells could be suitable to obtain in vitro osteocyte-like network for regenerative medicine. The originality of the present work consists in studying for the first time two different cell models (committed versus multipotent) compared in parallel different biomaterial cultures, thus suggesting distinct targets for each cellular model. Copyright 2012 Elsevier Ltd. All rights reserved
Effects of PTH(1-34) during fracture healing after experimental bone drilling in rat femur: novel aspects
Full text linkThe study concerns the role of PTH(1-34) during bone lesion repair. 3-month-old
male Sprague-Dawley rats, in which trans-cortical holes were drilled at femur middiaphysis,
were divided in groups with/without Teriparatide administration (40g/
Kg/day), and sacrificed at different times (10, 28, 45 days). In 2002 (1) we demonstrated
the occurrence of two successive bone forming processes during both skeletal
organogenesis and bone repair, i.e. static (SO) and dynamic (DO) osteogenesis: the
former (due to stationary osteoblasts, haphazardly grouped in cords) producing preliminary
bad quality trabecular bone, the latter (due to typical polarized osteoblasts
organized in ordered movable laminae) producing mechanically valid bone tissue.
In brief, the primary function of SO is to provide a rigid scaffold, containing osteocytes
(i.e. mechano-sensors), to DO-osteoblastic laminae; therefore, in DO mechanical
factors can play a crucial role in transduction of mechanical stresses into biological
signals. In the present work, histomorphometric analysis showed that, already after
10 days from drilling, notwithstanding the holes are temporarily filled by the same
amount of newly-formed trabecular bone (produced by SO) independently from the
treatment, the number of movable osteoblast laminae (typical of DO), covering the
trabecular surface, is statistically higher in animals submitted to PTH(1-34) administration
than in the control ones; this suggests that the mere effect of Teriparatide is
to anticipate the occurrence of dynamic osteogenesis involved in the production of
good quality bone more suitable to loading. These findings are also supported by the
higher values of microhardness as well as the more ordered-fibered texture (observed
by polarized light) in treated animals with respect to control ones that strongly indicates
the qualitative (instead of quantitative) effect of PTH (1-34) in improving bone
healing. The present investigation could be of crucial importance in further translational
clinical research in humans to define the best therapeutic strategies in recovering
skeletal lesions, particularly in terms of time of administration of PTH(1-34)
Up-regulation of the chemo-attractive receptor ChemR23 and occurrence of apoptosis in human chondrocytes isolated from fractured calcaneal osteochondral fragments
No full textTo study the expression level of a panel of pro/anti-apoptotic factors and inflammation-related receptors in
chondral fragments from patients undergoing surgical treatment for intra-articular calcaneal fractures, cartilage
fragments were retrieved from calcaneal fractures of 20 patients subjected to surgical treatment. Primary
cultures were performed using chondral fragments from fractured and control patients. Chondrocyte cultures
from each patient of the fractured and control groups were subjected to immunofluorescence staining and
quantitatively analyzed under confocal microscopy. Proteins extracted from the cultured chondrocytes taken
from the fractured and control groups were processed for Western blot experiments and densitometric analysis.
The percentage of apoptotic cells was determined using the cleaved PARP-1 antibody. The proportion of
labelled cells was 35% for fractured specimens, compared with 7% for control samples. Quantification of
caspase-3 active and Bcl-2 proteins in chondrocyte cultures showed a significant increase of the apoptotic
process in fractured specimens compared with control ones. Fractured chondrocytes were positively stained for
ChemR23 with statistically significant differences with respect to control samples. Densitometric evaluation of
the immunoreactive bands confirmed these observations. Human articular chondrocytes obtained from patients
with intra-articular calcaneal fractures express higher levels of pivotal pro-apoptotic factors, and of the chemoattractive
receptor ChemR23, compared with control cultures. On the basis of these observations, the authors
hypothesize that consistent prolonged chondrocyte death, associated with the persistence of high levels of proinflammatory
factors, could enhance the deterioration of cartilage tissue with consequent development of
post-traumatic arthritis following intra-articular bone fracture
Leptin effect on rat primary ossification centers during bone histogenesis.
No full textDuring the early phases of endochondral ossification, Leptin positive effects are shown in growith of rat ossification centers
Effect of PTH (1-34) on trabecular bone of rat vertebral body in induced-biochemical osteoporosis by calcium- deprived diet
Full text linkRats fed calcium-deprived diet were used as experimental model for studying bone modelling alterations during biochemical osteoporosis and recovery of bone loss. Such model is suitable to evaluate the possible effects exerted by PTH(1-34) in preventing as well as in recovering metabolic osteoporosis. Three-month-old Sprague Dawley male rats were divided in different groups: some fed normal diet or calcium-deprived diet with/without 40μg/Kg/day PTH(1-34), provided by Eli Lilly-USA, for 4 weeks and some with restoration of normal diet with/without PTH (1-34) for further 4 weeks. To evaluate the occurrence of osteogenesis during the first 4 weeks of the experimental period, rats received three labels of bone deposition at 1st, 20th and 27th day (and then were sacrificed); during the successive 4 weeks (in which those rats previously fed with calcium-deprived diet had restoration of normal diet), animals received three labels of bone deposition at 1st, 7th and 14th day. Histomorphometrical analyses were performed on cortical and trabecular bone taken from the central level of the 5th lumbar vertebral body, transversely sectioned. The results showed that differences among the groups were observed mainly in trabecular bone with respect to cortical one, thus underlining the different role of the two types of bone architecture in mineral and skeletal homeostasis. Concerning trabecular bone, the observations showed that administration of PTH (1-34) during calcium-deprived diet and/or during the restoration of normal diet induces higher deposition of trabecular bone with respect to that recorded in rats that never received PTH(1-34), neither during calcium-deprived diet nor during restoration of normal diet. Since increments of trabecular bone are detectable only after the period of diet restoration (but not before), the authors suggest that a chronic administration of PTH (1-34) is necessary to achieve appreciable results on bone mass recovery
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