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Trabeculae

Distribution by Scientific Domains

Medical Sciences	58%
Life Sciences	37%
Earth and Environmental Science	4%

Selected Abstracts

Ultrastructure of the ovary and oogenesis in six species of patellid limpets (Gastropoda: Patellogastropoda) from South Africa

INVERTEBRATE BIOLOGY, Issue 3 2000
Alan N. Hodgson
Abstract. The ultrastructural features of the ovary and oogenesis have been described in 6 species of patellid limpets from South Africa. The ovary is a complex organ that is divided radially into numerous compartments or lacunae by plate-like, blind-ended, hollow trabeculae that extend from the outer wall of the ovary to its central lumen. Trabeculae are composed of outer epithelial cells, intermittent smooth muscle bands, and extensive connective tissue. Oocytes arise within the walls of the trabeculae and progressively bulge outward into the ovarian lumen during growth while partially surrounded by squamous follicle cells. During early vitellogenesis, the follicle cells lift from the surface of the underlying oocytes and microvilli appear in the perivitelline space. Follicle cells restrict their contact with the oocytes to digitate foot processes that form desmosomes with the oolamina. When vitellogenesis is initiated, the trabecular epithelial cells hypertrophy and become proteosynthetically active. Yolk synthesis involves the direct incorporation of extraoocytic precursors from the lumen of the trabeculae (hemocoel) into yolk granules via receptor-mediated endocytosis. Lipid droplets arise de novo and Golgi complexes synthesize cortical granules that form a thin band beneath the oolamina. A fibrous jelly coat forms between the vitelline envelope and the overlying follicle cells in all species. [source]

Developmental morphology of the neonatal alligator (Alligator mississippiensis) ovary

JOURNAL OF MORPHOLOGY, Issue 3 2008
Brandon C. Moore
Abstract American alligator (Alligator mississippiensis) ovary development is incomplete at hatching. During the months following hatching, the cortical processes of oogenesis started in ovo continues and folliculogenesis is initiated. Additionally, the medullary region of the gonad undergoes dramatic restructuring. We describe alligator ovarian histology at hatching, 1 week, 1 month, and 3 months of age in order to characterize the timing of morphological development and compare these findings to chicken ovary development. At hatching, the ovarian cortex presents a germinal epithelium containing oogonia and a few primary oocytes irregularly scattered between somatic epithelial cells. The hatchling medulla shows fragmentation indicative of the formation of lacunae. By 1 week of age, oocytes form growing nests and show increased interactions with somatic cells, indicative of the initiation of folliculogenesis. Medullary lacunae increase in diameter and contain secretory material in their lumen. At 1 month, nest sizes and lacunar diameters continue to enlarge. Pachytene oocytes surrounded by somatic cells are more frequent. Trabeculae composed of dense irregular connective tissue divide cortical nests. Three months after hatching oocytes in meiotic stages of prophase I up to diplotene are present. The ovary displays many enlarged follicles with oocytes in diplotene arrest, thecal layers, lampbrush chromosomes, and complete layers of follicular cells. The medulla is an elaborated complex of vascularized lacunae underlying the cortex and often containing discrete lymphoid aggregates. While the general morphology of the alligator ovary is similar to that of the chicken ovary, the progression of oogenesis and folliculogenesis around hatching is notably slower in alligators. Diplotene oocytes are observed at hatching in chickens, but not until 3 months in alligators. Folliculogenesis is completed at 3 weeks in chickens whereas it is still progressing at 3 months in alligators. J. Morphol., 2008. © 2007 Wiley-Liss, Inc. [source]

Morphology of Haemal Nodes in the Roe Deer (Capreolus capreolus)

ANATOMIA, HISTOLOGIA, EMBRYOLOGIA, Issue 5 2010
Y. Akaydin Bozkurt
With 5 figures Summary The present study was aimed at the determination of the morphology of haemal nodes in the roe deer (Capreolus capreolus). The morphology of haemal nodes located in the abdominal and thoracic cavities of six roe deer (two adult male, two adult female and two foetuses) was studied by gross inspection and histological methods. Oval- and round-shaped haemal nodes with colours varying from pink to dark red were observed particularly between the abdominal aorta and caudal vena cava, and at the beginning of the main branches of the abdominal aorta. These nodes, having connection only with blood vessels, were covered with a thin or thick capsule of connective tissue in the foetus and the adult respectively. Trabeculae were not observed in foetal nodes. In adults, the capsule, trabeculae and, in particular, the sinuses were strongly supported by reticular fibres and cells. The morphology of these nodes displayed similarity to that of other ruminant species. [source]

Cardiac expression patterns of endothelin-converting enzyme (ECE): Implications for conduction system development

DEVELOPMENTAL DYNAMICS, Issue 6 2008
David Sedmera
Abstract The spatiotemporal distribution of the endothelin-converting enzyme (ECE) protein in the embryonic chick heart and the association of this polypeptide with the developing cardiac conduction system is described here for the first time. Further, we show how cardiac hemodynamic load directly affects ECE level and distribution. Endothelin (ET) is a cytokine involved in the inductive recruitment of Purkinje fibers. ET is produced by proteolytic cleavage of Big-ET by ECE. We generated an antibody against chick ECE recognizing a single band at ,70 kD to correlate the cardiac expression of this protein with that reported previously for its mRNA. ECE protein expression was more widespread compared to its mRNA, being present in endothelial cells, mesenchymal cells, and myocytes, and particularly enriched in the trabeculae and nascent ventricular conduction system. The myocardial expression was significantly modified under experimentally altered hemodynamic loading. In vivo, ET receptor blockade with bosentan delayed activation sequence maturation. These data support a role for ECE in avian cardiac conduction system differentiation and maturation. Developmental Dynamics 237:1746,1753, 2008. © 2008 Wiley-Liss, Inc. [source]

Platelet-derived growth factors in the developing avian heart and maturating coronary vasculature

DEVELOPMENTAL DYNAMICS, Issue 4 2005
Nynke M.S.
Abstract Platelet-derived growth factors (PDGFs) are important in embryonic development. To elucidate their role in avian heart and coronary development, we investigated protein expression patterns of PDGF-A, PDGF-B, and the receptors PDGFR-, and PDGFR-, using immunohistochemistry on sections of pro-epicardial quail,chicken chimeras of Hamburger and Hamilton (HH) 28,HH35. PDGF-A and PDGFR-, were expressed in the atrial septum, sinus venosus, and throughout the myocardium, with PDGFR-, retreating to the trabeculae at later stages. Additionally, PDGF-A and PDGFR-, were present in outflow tract cushion mesenchyme and myocardium, respectively. Small cardiac nerves and (sub)epicardial cells expressed PDGF-B and PDGFR-,. Furthermore, endothelial cells expressed PDGF-B, while vascular smooth muscle cells and interstitial epicardium-derived cells expressed PDGFR-,, indicating a role in coronary maturation. PDGF-B is also present in ventricular septal development, in the absence of any PDGFR. Epicardium-derived cells in the atrioventricular cushions expressed PDGFR-,. We conclude that all four proteins are involved in myocardial development, whereas PDGF-B and PDGFR-, are specifically important in coronary maturation. Developmental Dynamics 233:1579,1588, 2005. © 2005 Wiley-Liss, Inc. [source]

Age changes in bone microstructure: do they occur uniformly?

INTERNATIONAL JOURNAL OF OSTEOARCHAEOLOGY, Issue 6 2005
G. A. Macho
Abstract Age estimations based on conventional multifactorial methods were compared with trends observed in the internal morphology of bones obtained from high-resolution µCT. Specifically, average trabecular thickness and number of trabeculae/mm transect were determined in the non-load-bearing capitate (hand) and the load-bearing navicular (foot). The µCT findings reveal age-related trends but,surprisingly,these correspond only loosely with the ages assigned by conventional ageing methods, and are also not in accordance with what would be predicted from biomechanical considerations: trabeculae tend to be thinner in the (habitually) load-bearing navicular than in the (habitually) non-load-bearing capitate. While the statistically significant correlation between trabecular thickness and number of trabeculae would suggest a compensatory mechanism between these two aspects of microanatomy, they are not correlated with the assigned ages and, importantly, may differ between sexes. Only in females is there an unequivocal trend towards trabecular thickness increase with age. These findings, although unexpected, can be reconciled with recent histological evidence and assumed average activity levels in historical populations. Conversely, changes in trabecular number are less clear-cut and may be due to the lack of very old individuals in the sample. Nevertheless, the trends observed for trabecular thickness, as well as for trabecular number, seem to imply that the higher incidence of osteoporosis in women could be explained from a structural point of view alone. Copyright © 2005 John Wiley & Sons, Ltd. [source]

Ultrastructure of the ovary and oogenesis in six species of patellid limpets (Gastropoda: Patellogastropoda) from South Africa

Porosity of human mandibular condylar bone

JOURNAL OF ANATOMY, Issue 3 2007
G. A. P. Renders
Abstract Quantification of porosity and degree of mineralization of bone facilitates a better understanding of the possible effects of adaptive bone remodelling and the possible consequences for its mechanical properties. The present study set out first to give a three-dimensional description of the cortical canalicular network in the human mandibular condyle, in order to obtain more information about the principal directions of stresses and strains during loading. Our second aim was to determine whether the amount of remodelling was larger in the trabecular bone than in cortical bone of the condyle and to establish whether the variation in the amount of remodelling was related to the surface area of the cortical canals and trabeculae. We hypothesized that there were differences in porosity and orientation of cortical canals between various cortical regions. In addition, as greater cortical and trabecular porosities are likely to coincide with a greater surface area of cortical canals and trabeculae available for osteoblastic and osteoclastic activity, we hypothesized that this surface area would be inversely proportional to the degree of mineralization of cortical and trabecular bone, respectively. Micro-computed tomography was used to quantify porosity and mineralization in cortical and trabecular bone of ten human mandibular condyles. The cortical canals in the subchondral cortex of the condyle were orientated in the mediolateral direction, and in the anterior and posterior cortex in the superoinferior direction. Cortical porosity (average 3.5%) did not differ significantly between the cortical regions. It correlated significantly with the diameter and number of cortical canals, but not with cortical degree of mineralization. In trabecular bone (average porosity 79.3%) there was a significant negative correlation between surface area of the trabeculae and degree of mineralization; such a correlation was not found between the surface area of the cortical canals and the degree of mineralization of cortical bone. No relationship between trabecular and cortical porosity, nor between trabecular degree of mineralization and cortical degree of mineralization was found, suggesting that adaptive remodelling is independent and different between trabecular and cortical bone. We conclude (1) that the principal directions of stresses and strains are presumably directed mediolaterally in the subchondral cortex and superoinferiorly in the anterior and posterior cortex, (2) that the amount of remodelling is larger in the trabecular than in the cortical bone of the mandibular condyle; in trabecular bone variation in the amount of remodelling is related to the available surface area of the trabeculae. [source]

Fourier analysis methodology of trabecular orientation measurement in the human tibial epiphysis

JOURNAL OF ANATOMY, Issue 2 2001
M. HERRERA
Methods to quantify trabecular orientation are crucial in order to assess the exact trajectory of trabeculae in anatomical and histological sections. Specific methods for evaluating trabecular orientation include the ,point counting' technique (Whitehouse, 1974), manual tracing of trabecular outlines on a digitising board (Whitehouse, 1980), textural analysis (Veenland et al. 1998), graphic representation of vectors (Shimizu et al. 1993; Kamibayashi et al. 1995) and both mathematical (Geraets, 1998) and fractal analysis (Millard et al. 1998). Optical and computer-assisted methods to detect trabecular orientation of bone using the Fourier transform were introduced by Oxnard (1982) later refined by Kuo & Carter (1991) (see also Oxnard, 1993, for a review), in the analysis of planar sections of vertebral bodies as well as in planar radiographs of cancellous bone in the distal radius (Wigderowitz et al. 1997). At present no studies have applied this technique to 2-D images or to the study of dried bones. We report a universal computer-automated technique for assessing the preferential orientation of the tibial subarticular trabeculae based on Fourier analysis, emphasis being placed on the search for improvements in accuracy over previous methods and applied to large stereoscopic (2-D) fields of anatomical sections of dried human tibiae. Previous studies on the trajectorial architecture of the tibial epiphysis (Takechi, 1977; Maquet, 1984) and research data about trabecular orientation (Kamibayashi et al. 1995) have not employed Fourier analysis. [source]

Postpubertal Architectural Developmental Patterns Differ Between the L3 Vertebra and Proximal Tibia in Three Inbred Strains of Mice,

JOURNAL OF BONE AND MINERAL RESEARCH, Issue 12 2008
Helen R Buie
Abstract An understanding of normal microarchitectural bone development patterns of common murine models is needed. Longitudinal, structural, and mineralization trends were evaluated by in vivo ,CT over 12 time points from 6,48 wk of age at the vertebra and tibia of C3H/HeN, C57BL/6, and BALB/C mice. Longitudinal growth occurred rapidly until 8,10 wk, slowed as the growth plate bridged, and fused at 8,10 mo. Structural augmentation occurred through formation of trabeculae at the growth plate and thickening of existing ones. In the vertebrae, BV/TV increased rapidly until 12 wk in all strains. Between 12 and 32 wk, the architecture was stable with BV/TV deviating <1.1%, 1.6%, and 3.4% for the C57BL/6, BALB/C, and C3H/HeN mice. In contrast, the tibial architecture changed continuously but more moderately for BV/TV and TbTh compared with the vertebra and with comparable or larger changes for TbN and TbSp. Age-related trabecular deterioration (decreased BV/TV and TbN; increased TbSp and structure model index) was evident at both sites at 32 wk. In all strains, the cortex continued to develop after trabecular values peaked. The temporal plateau of BMD was variable across mouse strains and site, whereas tissue mineral density was attained at ,6 mo for all sites and strains. Geometric changes at the tibial diaphysis occurred rapidly until 8,10 wk, providing the C57BL/6 mice and C3H/HeN mice with the highest torsional and compressive rigidity, respectively. In summary, key skeletal development milestones were identified, and architectural topology at the vertebra was found to be more stable than at the tibia. [source]

Bisphosphonate-Induced Osteopetrosis: Novel Bone Modeling Defects, Metaphyseal Osteopenia, and Osteosclerosis Fractures After Drug Exposure Ceases,

JOURNAL OF BONE AND MINERAL RESEARCH, Issue 10 2008
Michael P Whyte
Abstract In 2003, we reported on a 12-yr-old boy who had developed osteopetrosis (OPT) while receiving pamidronate (PMD) for idiopathic bone pain and enigmatic elevation in circulating bone alkaline phosphatase. Now 17 yr of age, he was re-evaluated 6.5 yr after PMD exposure stopped. Our patient described less bone pain but further limb fractures. His growth plates were fused, yet hyperphosphatasemia persisted. Radiographs documented interval fractures of a metacarpal, an osteosclerotic distal radius, and a dense diaphyseal segment of an ulna where a "chalkstick" break remained incompletely healed after 2 yr. There was new L4 spondylolysis, and previous L5 spondylolysis had caused spondylolisthesis. Modeling disturbances of OPT persisted, but partial recovery was shown by metaphyseal surfaces with a unique concave shape. Metaphyseal osteosclerosis had remodeled imperfectly to become focal areas of dense, diaphyseal bone. Newer metaphyseal bone was unexpectedly osteopenic, especially in his distal femurs where cortices were thin and a paucity of trabeculae was documented by CT. Femoral necks had become short and wide with an abnormal contour. A "bone-within-bone" configuration was now present throughout his skeleton. In vertebrae, endplates were thin, and trabecular osteopenia was present central and peripheral to the bands of osteosclerosis. BMD Z-scores assessed by DXA had decreased into the normal range in his spine, hip, and whole body. Iliac crest biopsy showed active bone formation, with much less accumulated primary spongiosa than during the PMD infusions. Osteoclasts that had been dysmorphic, round cells without polarization and off of bone surfaces were now unremarkable in number, location, and appearance. In conclusion, bisphosphonate toxicity during childhood can impair skeletal modeling and remodeling with structural changes that evolve and carry into adult life. [source]

Recovery From Skeletal Fluorosis (an Enigmatic, American Case),,

JOURNAL OF BONE AND MINERAL RESEARCH, Issue 1 2007
Etah S Kurland
Abstract A 52-year-old man presented with severe neck immobility and radiographic osteosclerosis. Elevated fluoride levels in serum, urine, and iliac crest bone revealed skeletal fluorosis. Nearly a decade of detailed follow-up documented considerable correction of the disorder after removal of the putative source of fluoride (toothpaste). Introduction: Skeletal fluorosis, a crippling bone disorder, is rare in the United States, but affects millions worldwide. There are no data regarding its reversibility. Materials and Methods: A white man presented in 1996 with neck immobility and worsening joint pains of 7-year duration. Radiographs revealed axial osteosclerosis. Bone markers were distinctly elevated. DXA of lumbar spine (LS), femoral neck (FN), and distal one-third radius showed Z scores of +14.3, +6.6, and ,0.6, respectively. Transiliac crest biopsy revealed cancellous volume 4.5 times the reference mean, cortical width 3.2 times the reference mean, osteoid thickness 25 times the reference mean, and wide and diffuse tetracycline uptake documenting osteomalacia. Fluoride (F) was elevated in serum (0.34 and 0.29 mg/liter [reference range: <0.20]), urine (26 mg/liter [reference range: 0.2,1.1 mg/liter]), and iliac crest (1.8% [reference range: <0.1%]). Tap and bottled water were negative for F. Surreptitious ingestion of toothpaste was the most plausible F source. Results: Monitoring for a decade showed that within 3 months of removal of F toothpaste, urine F dropped from 26 to 16 mg/liter (reference range: 0.2,1.1 mg/liter), to 3.9 at 14 months, and was normal (1.2 mg/liter) after 9 years. Serum F normalized within 8 months. Markers corrected by 14 months. Serum creatinine increased gradually from 1.0 (1997) to 1.3 mg/dl (2006; reference range: 0.5,1.4 mg/dl). Radiographs, after 9 years, showed decreased sclerosis of trabeculae and some decrease of sacrospinous ligament ossification. DXA, after 9 years, revealed 23.6% and 15.1% reduction in LS and FN BMD with Z scores of +9.3 and +4.8, respectively. Iliac crest, after 8.5 years, had normal osteoid surface and thickness with distinct double labels. Bone F, after 8.5 years, was 1.15% (reference range, <0.1), which was a 36% reduction (still 10 times the reference value). All arthralgias resolved within 2 years, and he never fractured, but new-onset nephrolithiasis occurred within 9 months and became a chronic problem. Conclusions: With removal of F exposure, skeletal fluorosis is reversible, but likely impacts for decades. Patients should be monitored for impending nephrolithiasis. [source]

Surveillance for Early Detection of Aggressive Parathyroid Disease: Carcinoma and Atypical Adenoma in Familial Isolated Hyperparathyroidism Associated With a Germline HRPT2 Mutation,,

JOURNAL OF BONE AND MINERAL RESEARCH, Issue 10 2006
Thomas G Kelly
Abstract Familial hyperparathyroid syndromes involving mutations of HRPT2 (also CDC73), a tumor suppressor, are important to identify because the relatively high incidence of parathyroid malignancy associated with such mutations warrants a specific surveillance strategy. However, there is a dearth of reports describing experience with surveillance and early detection informed by genetic insight into this disorder. Introduction: Familial isolated hyperparathyroidism (FIHP) is a rare cause of parathyroid (PT) tumors without other neoplasms or endocrinopathies. Germline mutations in CASR, MEN1, and rarely, HRPT2 have been identified in kindreds with FIHP. HRPT2 mutations may be enriched in FIHP families with PT carcinoma, underscoring the importance of identifying causative mutations. Materials and Methods: A 13-year-old boy, whose father had died of PT carcinoma, developed primary hyperparathyroidism. A left superior PT mass was identified by ultrasonography and removed surgically. Aggressive histological features of the boy's tumor included fibrous trabeculae, mitoses, and microscopic capsular infiltration. Two years later, under close biochemical surveillance, primary hyperparathyroidism recurred 5 months after documentation of normocalcemia and normal parathyroid status. Ultrasound and MRI identified a newly enlarged right superior PT gland but indicated no recurrent disease in the left neck. Histologic features typical of a benign adenoma were evident after surgical extirpation of the gland. Results: Leukocyte DNA analysis revealed a frameshift mutation in exon 2 of HRPT2. The initial tumor manifested the expected germline HRPT2 mutation, plus a distinct somatic frameshift mutation, consistent with the Knudson "two hit" concept of biallelic inactivation of a classic tumor suppressor gene. Genetic screening of the patient's 7 asymptomatic and previously normocalcemic siblings revealed three with the same germline HRPT2 mutation. One of the siblings newly identified as mutation-positive was noted to be hypercalcemic at the time of the genetic screening. He was found to have a PT adenoma with aggressive features. Two of the five children of another mutation-positive sibling also carry the same HRPT2 mutation. Conclusions: Despite the reported rarity of HRPT2 mutations in FIHP, a personal or family history of PT carcinoma in FIHP mandates serious consideration of germline HRPT2 mutation status. This information can be used in diagnostic and management considerations, leading to early detection and removal of potentially malignant parathyroid tumors. [source]

Prevention of Postmenopausal Bone Loss by a Low-Magnitude, High-Frequency Mechanical Stimuli: A Clinical Trial Assessing Compliance, Efficacy, and Safety,

JOURNAL OF BONE AND MINERAL RESEARCH, Issue 3 2004
Clinton Rubin
Abstract A 1-year prospective, randomized, double-blind, and placebo-controlled trial of 70 postmenopausal women demonstrated that brief periods (<20 minutes) of a low-level (0.2g, 30 Hz) vibration applied during quiet standing can effectively inhibit bone loss in the spine and femur, with efficacy increasing significantly with greater compliance, particularly in those subjects with lower body mass. Introduction: Indicative of the anabolic potential of mechanical stimuli, animal models have demonstrated that short periods (<30 minutes) of low-magnitude vibration (<0.3g), applied at a relatively high frequency (20,90 Hz), will increase the number and width of trabeculae, as well as enhance stiffness and strength of cancellous bone. Here, a 1-year prospective, randomized, double-blind, and placebo-controlled clinical trial in 70 women, 3,8 years past the menopause, examined the ability of such high-frequency, low-magnitude mechanical signals to inhibit bone loss in the human. Materials and Methods: Each day, one-half of the subjects were exposed to short-duration (two 10-minute treatments/day), low-magnitude (2.0 m/s2 peak to peak), 30-Hz vertical accelerations (vibration), whereas the other half stood for the same duration on placebo devices. DXA was used to measure BMD at the spine, hip, and distal radius at baseline, and 3, 6, and 12 months. Fifty-six women completed the 1-year treatment. Results and Conclusions: The detection threshold of the study design failed to show any changes in bone density using an intention-to-treat analysis for either the placebo or treatment group. Regression analysis on the a priori study group demonstrated a significant effect of compliance on efficacy of the intervention, particularly at the lumbar spine (p = 0.004). Posthoc testing was used to assist in identifying various subgroups that may have benefited from this treatment modality. Evaluating those in the highest quartile of compliance (86% compliant), placebo subjects lost 2.13% in the femoral neck over 1 year, whereas treatment was associated with a gain of 0.04%, reflecting a 2.17% relative benefit of treatment (p = 0.06). In the spine, the 1.6% decrease observed over 1 year in the placebo group was reduced to a 0.10% loss in the active group, indicating a 1.5% relative benefit of treatment (p = 0.09). Considering the interdependence of weight, the spine of lighter women (<65 kg), who were in the highest quartile of compliance, exhibited a relative benefit of active treatment of 3.35% greater BMD over 1 year (p = 0.009); for the mean compliance group, a 2.73% relative benefit in BMD was found (p = 0.02). These preliminary results indicate the potential for a noninvasive, mechanically mediated intervention for osteoporosis. This non-pharmacologic approach represents a physiologically based means of inhibiting the decline in BMD that follows menopause, perhaps most effectively in the spine of lighter women who are in the greatest need of intervention. [source]

Irreversible Perforations in Vertebral Trabeculae?,

JOURNAL OF BONE AND MINERAL RESEARCH, Issue 7 2003
X Banse
In human cancellous bone, osteoclastic perforations resulting from normal remodeling were generally considered irreversible. In human vertebral samples, examined by backscatter electron microscopy, there was clear evidence of bridging of perforation defects by new bone formation. Hence trabecular perforations may not be irreversible. Introduction: Preservation of the trabecular bone microarchitecture is essential to maintain its load-bearing capacity and prevent fractures. However, during bone remodeling, the osteoclasts may perforate the platelike trabeculae and disconnect the structure. Large perforations (>100 ,m) are generally considered irreversible because there is no surface on which new bone can be laid down. In this work, we investigated the outcome of these perforations on human vertebral cancellous bone. Materials and Methods: Using backscatter electron microscopy, we analyzed 264 vertebral bone samples from the thoracic and lumbar spine of nine subjects (44,88 years old). Nine fields (2 × 1.5 mm) were observed on each block. Several bone structural units (BSUs) were visible on a single trabecula, illustrating a dynamic, historical aspect of bone remodeling. A bridge was defined as a single and recent BSU connecting two segments of trabeculae previously separated by osteoclastic resorption. They were counted and measured (length and breadth, ,m). Results and Conclusion: We observed 396 bridges over 2376 images. By comparison, we found only 15 microcalluses on the same material. The median length of the bridge was 165 ,m (range, 29,869 ,m); 86% being longer than 100 ,m and 35% longer than 200 ,m. Their breadth was 56 ,m (range, 6,255 ,m), but the thinnest were still in construction. Bridges were found in all nine subjects included in the study, suggesting that it is a common feature of normal vertebral bone remodeling. These observations support the hypothesis that perforation could be repaired by new bone formation. and hence, might not be systematically irreversible. [source]

Quantity and Quality of Trabecular Bone in the Femur Are Enhanced by a Strongly Anabolic, Noninvasive Mechanical Intervention

JOURNAL OF BONE AND MINERAL RESEARCH, Issue 2 2002
Clinton Rubin Ph.D.
Abstract The skeleton's sensitivity to mechanical stimuli represents a critical determinant of bone mass and morphology. We have proposed that the extremely low level (<10 microstrain), high frequency (20-50 Hz) mechanical strains, continually present during even subtle activities such as standing are as important to defining the skeleton as the larger strains typically associated with vigorous activity (>2000 microstrain). If these low-level strains are indeed anabolic, then this sensitivity could serve as the basis for a biomechanically based intervention for osteoporosis. To evaluate this hypothesis, the hindlimbs of adult female sheep were stimulated for 20 minutes/day using a noninvasive 0.3g vertical oscillation sufficient to induce approximately 5 microstrain on the cortex of the tibia. After 1 year of stimulation, the physical properties of 10-mm cubes of trabecular bone from the distal femoral condyle of experimental animals (n = 8) were compared with controls (n = 9), as evaluated using microcomputed tomography (,CT) scanning and materials testing. Bone mineral content (BMC) was 10.6% greater (p < 0.05), and the trabecular number (Tb.N) was 8.3% higher in the experimental animals (p < 0.01), and trabecular spacing decreased by 11.3% (p < 0.01), indicating that bone quantity was increased both by the creation of new trabeculae and the thickening of existing trabeculae. The trabecular bone pattern factor (TBPf) decreased 24.2% (p < 0.03), indicating trabecular morphology adapting from rod shape to plate shape. Significant increases in stiffness and strength were observed in the longitudinal direction (12.1% and 26.7%, respectively; both, p < 0.05), indicating that the adaptation occurred primarily in the plane of weightbearing. These results show that extremely low level mechanical stimuli improve both the quantity and the quality of trabecular bone. That these deformations are several orders of magnitude below those peak strains which arise during vigorous activity indicates that this biomechanically based signal may serve as an effective intervention for osteoporosis. [source]

The Skeletal Structure of Insulin-Like Growth Factor I-Deficient Mice

JOURNAL OF BONE AND MINERAL RESEARCH, Issue 12 2001
Daniel Bikle
Abstract The importance of insulin-like growth factor I (IGF-I) for growth is well established. However, the lack of IGF-I on the skeleton has not been examined thoroughly. Therefore, we analyzed the structural properties of bone from mice rendered IGF-I deficient by homologous recombination (knockout [k/o]) using histomorphometry, peripheral quantitative computerized tomography (pQCT), and microcomputerized tomography (,CT). The k/o mice were 24% the size of their wild-type littermates at the time of study (4 months). The k/o tibias were 28% and L1 vertebrae were 26% the size of wild-type bones. Bone formation rates (BFR) of k/o tibias were 27% that of the wild-type littermates. The k/o bones responded normally to growth hormone (GH; 1.7-fold increase) and supranormally to IGF-I (5.2-fold increase) with respect to BFR. Cortical thickness of the proximal tibia was reduced 17% in the k/o mouse. However, trabecular bone volume (bone volume/total volume [BV/TV]) was increased 23% (male mice) and 88% (female mice) in the k/o mice compared with wild-type controls as a result of increased connectivity, increased number, and decreased spacing of the trabeculae. These changes were either less or not found in L1. Thus, lack of IGF-I leads to the development of a bone structure, which, although smaller, appears more compact. [source]

Infrared Microscopic Imaging of Bone: Spatial Distribution of CO32,

JOURNAL OF BONE AND MINERAL RESEARCH, Issue 5 2001
H. Ou-Yang
Abstract This article describes a novel technology for quantitative determination of the spatial distribution of CO32, substitution in bone mineral using infrared (IR) imaging at ,6 ,m spatial resolution. This novel technology consists of an IR array detector of 64 × 64 elements mapped to a 400 ,m × 400 ,m spot at the focal plane of an IR microscope. During each scan, a complete IR spectrum is acquired from each element in the array. The variation of any IR parameter across the array may be mapped. In the current study, a linear relationship was observed between the band area or the peak height ratio of the CO32, v3 contour at 1415 cm,1 to the PO43, v1,v3 contour in a series of synthetic carbonated apatites. The correlation coefficient between the spectroscopically and analytically determined ratios (R2 = 0.989) attests to the practical utility of this IR area ratio for determination of bone CO32, levels. The relationship forms the basis for the determination of CO32, in tissue sections using IR imaging. In four images of trabecular bone the average CO32, levels were 5.95 wt% (2298 data points), 6.67% (2040 data points), 6.66% (1176 data points), and 6.73% (2256 data points) with an overall average of 6.38 ± 0.14% (7770 data points). The highest levels of CO32, were found at the edge of the trabeculae and immediately adjacent to the Haversian canal. Examination of parameters derived from the phosphate v1,v3 contour of the synthetic apatites revealed that the crystallinity/perfection of the hydroxyapatite (HA) crystals was diminished as CO32, levels increased. The methodology described will permit evaluation of the spatial distribution of CO32, levels in diseased and normal mineralized tissues. [source]

A Three-Dimensional Simulation of Age-Related Remodeling in Trabecular Bone,

JOURNAL OF BONE AND MINERAL RESEARCH, Issue 4 2001
J. C. Van Der Linden
Abstract After peak bone mass has been reached, the bone remodeling process results in a decrease in bone mass and strength. The formation deficit, the deficit of bone formation compared with previous resorption, results in bone loss. Moreover, trabeculae disconnected by resorption cavities probably are not repaired. The contributions of these mechanisms to the total bone loss are unclear. To investigate these contributions and the concomitant changes in trabecular architecture and mechanical properties, we made a computer simulation model of bone remodeling using microcomputed tomography (micro-CT) scans of human vertebral trabecular bone specimens. Up to 50 years of physiological remodeling were simulated. Resorption cavities were created and refilled 3 months later. These cavities were not refilled completely, to simulate the formation deficit. Disconnected trabeculae were not repaired; loose fragments generated during the simulation were removed. Resorption depth, formation deficit, and remodeling space were based on biological data. The rate of bone loss varied between 0.3% and 1.1% per year. Stiffness anisotropy increased, and morphological anisotropy (mean intercept length [MIL]) was almost unaffected. Connectivity density increased or decreased, depending on the remodeling parameters. The formation deficit accounted for 69,95%, disconnected trabeculae for 1,21%, and loose fragments for 1,17% of the bone loss. Increasing formation deficit from 1.8% to 5.4% tripled bone loss but only doubled the decrease in stiffness. Increasing resorption depth from 28 to 56 ,m slightly increased bone loss but drastically decreased stiffness. Decreasing the formation deficit helps to prevent bone loss, but reducing resorption depth is more effective in preventing loss of mechanical stiffness. [source]

Daidzein but not other phytoestrogens preserves bone architecture in ovariectomized female rats in vivo

JOURNAL OF CELLULAR BIOCHEMISTRY, Issue 6 2008
D. Somjen
Abstract Ovariectomy of immature female rats, results in significant decrease of trabecular bone volume and in cortical bone thickness. Previously, we found that estradiol-17, (E2) restored bone structure of ovariectomized (Ovx) female rats to values obtained in intact sham-operated female rats. E2 also selectively stimulated creatine kinase (CK) specific activity a hormonal-genomic activity marker. In the present study, we compared the effects of E2 and the phytoestrogens: daidzein (D), biochainin A (BA), genistein (G), carboxy-derivative of BA (cBA), and the SERM raloxifene (Ral) in Ovx, on both histological changes of bones and CK, when administered in multiple daily injections for 2.5 months. Bone from Ovx rats, showed significant disrupted architecture of the growth plate, with fewer proliferative cells and less chondroblasts. The metaphysis underneath the growth plate, contained less trabeculae but a significant increased number of adipocytes in the bone marrow. D like E2 and Ral but not G, BA, or cBA, restored the morphology of the tibiae, similar to that of control sham-operated animals; the bony trabeculeae observed in the primary spongiosa was thicker, with almost no adipocytes in bone marrow. Ovariectomy resulted also in reduced CK, which in both epiphysis and diaphysis was stimulated by all estrogenic compounds tested. In summary, only D stimulated skeletal tissues growth and differentiation as effectively as E2 or Ral, suggesting that under our experimental conditions, D is more effective in reversing menopausal changes than any of the other isolated phytoestrogens which cannot be considered as one entity. J. Cell. Biochem. 103: 1826,1832, 2007. © 2007 Wiley-Liss, Inc. [source]

Sevoflurane- and Desflurane-induced human myocardial post-conditioning through Phosphatidylinositol-3-kinase/Akt signalling

ACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 7 2009
L. ZHU
Background: The role of phosphatidylinositol-3-kinase (PI3K) in sevoflurane- and desflurane-induced myocardial post-conditioning remains unknown. Methods: We recorded isometric contraction of isolated human right atrial trabeculae (oxygenated Tyrode's at 34 °C, stimulation frequency 1 Hz). In all groups, a 30-min hypoxic period was followed by a 60-min reoxygenation period. At the onset of reoxygenation, muscles were exposed to 5 min of sevoflurane 1%, 2%, and 3%, and desflurane 3%, 6%, and 9%. In separate groups, sevoflurane 2% and desflurane 6% were administered in the presence of 100 nM wortmannin, a PI3K inhibitor. Recovery of force after the 60-min reoxygenation period was compared between groups (mean ± SD). Result: As compared with the Control group (49 ± 7% of baseline) PostC by sevoflurane 1%, 2%, and 3% (78 ± 4%, 79 ± 5%, and 85 ± 4% of baseline, respectively) and desflurane 3%, 6%, and 9% (74 ± 5%, 84 ± 4%, and 86 ± 11% of baseline, respectively) enhanced the recovery of force. This effect was abolished in the presence of wortmannin (56 ± 5% of baseline for sevoflurane 2%+wortmannin; 56 ± 3% of baseline for desflurane 6%+wortmannin). Wortmannin alone had no effect on the recovery of force (57 ± 7% of baseline). Conclusion: In vitro, sevoflurane and desflurane post-conditioned human myocardium against hypoxia through activation of phosphatidylinositol-3-kinase. [source]

Aggressive osteogenic desmoplastic melanoma: a case report

JOURNAL OF CUTANEOUS PATHOLOGY, Issue 5 2007
Patrick O. Emanuel
A case of an osteogenic desmoplastic melanoma occurring on the sole of the foot of a 60-year-old African American man is described. The tumor measured 4.8 cm in greatest dimension, invaded to a thickness of 2.2 cm and metastasized to four of ten inguinal lymph nodes. The majority of the tumor had a classic desmoplastic phenotype with malignant spindle cells set in a sclerotic and myxoid matrix and foci of lymphocyte aggregation. In other areas, there were thick trabeculae of bone rimmed by malignant epithelioid melanocytes. There was a markedly atypical lentiginous hyperplasia in the overlying epidermis. Imaging showed no continuity with the underlying calcaneus. The tumor was characterized immunohistochemically by S100 positivity. Pathologists should be aware of this diagnosis and should differentiate it from osteosarcoma. [source]

A new method for three-dimensional skeleton graph analysis of porous media: application to trabecular bone microarchitecture

JOURNAL OF MICROSCOPY, Issue 2 2000
L. Pothuaud
This paper introduces a new three-dimensional analysis of complex disordered porous media. Skeleton graph analysis is described and applied to trabecular bone images obtained by high resolution magnetic resonance imaging. This technique was developed bearing in mind topological considerations. The correspondence between vertices and branches of the skeleton graph and trabeculae is used in order to get local information on trabecular bone microarchitecture. In addition to real topological parameters, local structural information about trabeculae, such as length and volume distributions, are obtained. This method is applied to two sets of samples: six osteoporosis and six osteoarthritis bone samples. We demonstrate that skeleton graph analysis is a powerful technique to describe trabecular bone microarchitecture. [source]

Formation of the chondrocranium of Trachemys scripta (Reptilia: Testudines: Emydidae) and a comparison with other described turtle taxa

JOURNAL OF MORPHOLOGY, Issue 2 2007
Frank J. Tulenko
Abstract Few descriptions of the formation of the chelonian chondrocranium exist. Herein, developmental stages critical to the formation of the chondrocranium of the Red-eared Slider, Trachemys scripta (Testudines: Emydidae), are described and illustrated, with particular attention given to ontogenetic changes that take place in the orbitotemporal region of the skull. Morphological descriptions are based on cleared and double-stained and serially-sectioned embryos. These specimens allowed for a detailed evaluation of the developmental morphology of the trabeculae, interorbital septum, pilae metoptica, taeniae marginalis, acrochordal cartilage, pilae antotica, parachordal cartilages, and crista sellaris. Additionally, the formation of the chondrocranium of T. scripta is compared to those of Chrysemys picta (Emydidae) and Caretta caretta (Chelonidae). Overall, the patterns of formation and remodeling of the chondrocranium are quite similar among these species, with the most conspicuous differences observed in remodeling of the posterior orbital cartilages (specifically, the pila metoptica). Reorganization of these cartilages is discussed briefly in the context of associated extraocular muscles for T. scripta and C. caretta. A prominent intertrabecula is reported in T. scripta, supporting previous observations of this structure in emydid turtles. J. Morphol., 2007. © 2007 Wiley-Liss, Inc. [source]

Skeletal development of the Mexican spadefoot, Spea multiplicata (Anura: Pelobatidae)

JOURNAL OF MORPHOLOGY, Issue 7 2006
Barbara Banbury
Abstract The larval chondrocranium of Spea multiplicata is described, as is the development and adult morphology of the skeleton. There are major modifications to the larval chondrocranium throughout development, including the presence of embryonic trabeculae in young tadpoles and significant reorganization of cartilaginous structures at metamorphosis. The first bone to ossify is the parasphenoid (Stage 35), followed by the presacral neural arches, ilium, and femur (Stage 36). By Stage 39, most of the postcranial elements have begun to ossify. Metamorphic climax is accomplished over three Gosner stages (39,41) and involves major modifications to the chondrocranium, as well as the appearance of three cranial elements (septomaxilla, nasal, and premaxilla). After metamorphosis, the exoccipital, vomer, dentary, angulosplenial, squamosal, pterygoid, sphenethmoid, ischium, and hyoid begin to ossify. The stapes, mentomeckelian, operculum, carpals, and tarsals do not appear until juvenile and adult stages. The development of the hyoid and cartilaginous condensations of the carpals and tarsals are described. In addition, phenotypic plasticity within the genus and the absence of a palatine (= neopalatine) bone are discussed. J. Morphol. © 2006 Wiley-Liss, Inc. [source]

Micro-computed tomography evaluation of vertebral end-plate trabecular bone changes in a porcine asymmetric vertebral tether

JOURNAL OF ORTHOPAEDIC RESEARCH, Issue 2 2010
Jean-Michel Laffosse
Abstract We conducted a micro-CT analysis of subchondral bone of the vertebral end-plates after application of compressive stress. Thoracic and lumbar vertebral units were instrumented by carrying out left asymmetric tether in eleven 4-week-old pigs. After 3 months of growth, instrumented units and control units were harvested. Micro-CT study of subchondral bone was performed on one central and two lateral specimens (fixated side and non-fixated side). In control units, bone volume fraction (BV/TV), number of trabeculae (Tb.N), trabecular thickness (Tb.Th), and degree of anisotropy (DA) were significantly higher, whereas intertrabecular space (Tb.Sp) was significantly lower in center than in periphery. No significant difference between the fixated and non-fixated sides was found. In instrumented units, BV/TV, Tb.N, Tb.Th, and DA were significantly higher in center than in periphery. BV/TV, Tb.N, and Conn.D were significantly higher in fixated than in non-fixated side, while Tb.Sp was significantly lower. We noted BV/TV, Tb.N, and Tb.Th significantly lower, and Tb.Sp significantly higher, in the instrumented levels. This study showed, in instrumented units, two opposing processes generating a reorganization of the trabecular network. First, an osteolytic process (decrease in BV/TV, Tb.N, Tb.Th) by stress-shielding, greater in center and on non-fixated side. Second, an osteogenic process (higher BV/TV, Tb.N, Conn.D, and lower Tb.Sp) due to the compressive loading induced by growth on the fixated side. This study demonstrates the densification of the trabecular bone tissue of the vertebral end-plates after compressive loading, and illustrates the potential risks of excessively rigid spinal instrumentation which may induce premature osteopenia. © 2009 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 28:232,240, 2010 [source]

The Effect of a Constant Electrical Field on Osseointegration after Immediate Implantation in Dog Mandibles: A Preliminary Study

JOURNAL OF PROSTHODONTICS, Issue 5 2007
Yadollah Soleymani Shayesteh DDS
Purpose: The long time span between insertion of implants and functional rehabilitation often inconveniences patients. Accelerating bone growth around dental implants can shorten this time span. This in vivo study evaluated the effect of a constant electrical field on bone growth around dental implants. Materials and Methods: Four mongrel dogs were used in this study. Sixteen dental implants were placed immediately after extraction of the first premolar and molar teeth. A constant electrical field (CEF) generator was placed in the mucoperiostal pouch created from the subperiostral dissection under the inferior border of the dog's mandible and connected to the experiment side fixtures. CEF provided 3 V of electrical potential during osseointegration. Histologic sections were stained with hematoxylin,eosin and observed under light microscopy. The sections were analyzed histomorphometrically to calculate the amount of newly formed bone. Statistical analysis was performed with SPSS 11.0 computer software (,= 0.05). Results: At the end of the first stage of the osseointegration (90 days) CEF group sections showed enhanced growth of the trabeculae compared with the control group. Statistical analysis revealed significant differences between experimental and control groups. Bone contact ratio was statistically significant in the experimental group (p= 0.001). An increase in the local bone formation and bone contact ratio was observed with direct electrical stimulation of the implant and the bone area around the implant. Conclusion: Minimal direct electrical current, which can produce an electrical field around the implant, can increase the amount of bone formation and decrease the time of osseointegration. [source]

Histological structure of the cancellous bone layer in Bothriolepis canadensis (Antiarchi, Placodermi)

LETHAIA, Issue 3 2005
CAROLE BURROW
The Placodermi are extinct basal gnathostomes which had extensive dermal and perichondral bone, but which lacked the endochondral bone which characterizes the more derived bony fishes. Thin sections of bone from a specimen of the antiarch placoderm Bothriolepis canadensis, from the Escuminac Formation (Frasnian, Upper Devonian), Québec, Canada, reveal that part of the cancellous layer in its dermal and endoskeletal bone formed from perichondral bone trabeculae growing around cartilage spheres. The resultant structure mimics that of osteichthyan endochondral bone. The layout and dimensions of this polygonal mosaic patterning of the bone trabeculae and flattened cartilage spheres resemble those of the prismatic layers of calcified cartilage in chondrichthyans. If the lack of endoskeletal bone in chondrichthyans is a derived character, then the structure identified in B. canadensis could represent a ,template' for the formation of prismatic calcified cartilage in the absence of bone. [source]

Trabecular bone volume fraction mapping by low-resolution MRI

MAGNETIC RESONANCE IN MEDICINE, Issue 1 2001
M.A. Fernández-Seara
Abstract Trabecular bone volume fraction (TBVF) is highly associated with the mechanical competence of trabecular bone. TBVF is ordinarily measured by histomorphometry from bone biopsies or, noninvasively, by means of high-resolution microcomputed tomography and, more recently, by micro-MRI. The latter methods require spatial resolution sufficient to resolve trabeculae, along with segmentation techniques that allow unambiguous assignment of the signal to bone or bone marrow. In this article it is shown that TBVF can be measured under low-resolution conditions by exploiting the attenuation of the MR signal resulting from fractional occupancy of the imaging voxel by bone and bone marrow, provided that a reference signal is available from a marrow volume devoid of trabeculation. The method requires accurate measurement of apparent proton density, which entails correction for various sources of error. Key among these are the spatial nonuniformity in the RF field amplitude and effects of the slice profile, which are determined by B1 field mapping and numerical integration of the Bloch equations, respectively. By contrast, errors from variations in bone marrow composition (hematopoietic vs. fatty) between trabecular and reference site are predicted to be small and usually negligible. The method was evaluated in phantoms and in vivo in the distal radius and found to be accurate to 1% in marrow volume fraction. Finally, in a group of 12 patients of varying skeletal status, TBVF in the calcaneus was found to strongly correlate with integral bone mineral density of the lumbar vertebrae (r2 = 0.83, p < 0.0001). The method may fail in large imaging objects such as the human trunk at high magnetic field where standing wave and RF penetration effects cause intensity variations that cannot be corrected. Magn Reson Med 46:103,113, 2001. © 2001 Wiley-Liss, Inc. [source]

Quantitative MRI for the assessment of bone structure and function,

NMR IN BIOMEDICINE, Issue 7 2006
Felix W. Wehrli
Abstract Osteoporosis is the most common degenerative disease in the elderly. It is characterized by low bone mass and structural deterioration of bone tissue, leading to morbidity and increased fracture risk in the hip, spine and wrist,all sites of predominantly trabecular bone. Bone densitometry, currently the standard methodology for diagnosis and treatment monitoring, has significant limitations in that it cannot provide information on the structural manifestations of the disease. Recent advances in imaging, in particular MRI, can now provide detailed insight into the architectural consequences of disease progression and regression in response to treatment. The focus of this review is on the emerging methodology of quantitative MRI for the assessment of structure and function of trabecular bone. During the past 10 years, various approaches have been explored for obtaining image-based quantitative information on trabecular architecture. Indirect methods that do not require resolution on the scale of individual trabeculae and therefore can be practiced at any skeletal location, make use of the induced magnetic fields in the intertrabecular space. These fields, which have their origin in the greater diamagnetism of bone relative to surrounding marrow, can be measured in various ways, most typically in the form of R2,, the recoverable component of the total transverse relaxation rate. Alternatively, the trabecular network can be quantified by high-resolution MRI (µ-MRI), which requires resolution adequate to at least partially resolve individual trabeculae. Micro-MRI-based structure analysis is therefore technically demanding in terms of image acquisition and algorithms needed to extract the structural information under conditions of limited signal-to-noise ratio and resolution. Other requirements that must be met include motion correction and image registration, both critical for achieving the reproducibility needed in repeat studies. Key clinical applications targeted involve fracture risk prediction and evaluation of the effect of therapeutic intervention. Copyright © 2006 John Wiley & Sons, Ltd. [source]