Observations and quantitative radioautographic studies of calcium45 deposited in vivo in forming Haversian systems and old bone of rabbit.
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Animals↗
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Microchemical studies on single Haversian systems. IV. Distribution of calcium, phosphorus and nitrogen in bone tissue from a case of osteopetrosis.
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Bone and Bones↗
Osteocyte density in aging subjects is enhanced in bone adjacent to remodeling haversian systems.
The osteocyte is a candidate regulatory cell for bone remodeling. Previously, we demonstrated that there is a substantial (approximately 50%) loss of osteocytes from their lacunae in the cortex of the elderly femoral neck. Higher occupancy was evident in tissue exhibiting high remodeling and high porosity. The present study examines the distribution of osteocytes within individual osteonal systems at differing stages of the remodeling cycle. In 22 subjects, lacunar density, osteocyte density, and their quotient, the percent lacunar occupancy, was assessed up to a distance of 65 microm from the canal surface in six quiescent, resorbing, and forming osteons. In both forming (p = 0.024) and resorbing (p = 0.034) osteons, osteocyte densities were significantly higher in cases of hip fracture than controls. However, there were no significant between-group differences in lacunar occupancy. In both cases and controls, osteocyte density (p < 0.0001; mean difference +/-SEM: 157 +/- 34/mm2) and lacunar occupancy (p = 0.025; mean difference: 8.1 +/- 3.4%) were shown to be significantly higher in forming compared with quiescent osteons. Interestingly, resorbing systems also exhibited significantly elevated osteocyte density in both the fracture and the control group combined (mean difference 76 +/- 23/mm2; p = 0.003). Lacunar occupancy was also greater in resorbing compared with quiescent osteons (both groups combined: p = 0.022; mean difference: 5.7 +/- 2.3%). Elevated osteocyte density and lacunar occupancy in forming compared with quiescent systems was expected because of the likely effects of aging on quiescent osteons. However, the higher levels of these parameters in resorbing compared with quiescent systems was the opposite of what we expected and suggests that, in addition to their postulated mechanosensory role in the suppression of remodeling and bone loss, osteocytes might also contribute to processes initiating or maintaining bone resorption.
Aged↗
Diaphyseal dysplasia (englemann's syndrome). A case report demonstrating a deficiency in cortical haversian system formation.
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Bone Diseases, Developmental↗
Effect of chronic low-level cadmium intoxication on the Haversian remodeling system in dogs.
This experiment was carried out in order to determine whether the chronic administration of low doses of cadmium resulted in an alteration of the haversian bone remodeling system in dogs. Two pairs of littermate beagles were administered 25 ppm cadmium chloride in their drinking water for 6 months. Four beagles matched for age and sex from the same colony served as controls. By means of fluorescent labeling, we measured haversian bone remodeling parameters according to the techniques described by Frost. Statistical analysis of the results showed significant changes at the 0.01 level in: activation frequency, appositional rates, and number of osteoid seams. At the 0.05 level, significant differences were found in the number of resorption spaces and the bone formation rate. In the absence of other evidence indicative of an alteration in the internal milieu of the dogs, it is concluded that a direct toxic action of cadmium on the mechanisms of activation of cells responsible for the creation and formation of new haversian systems cannot be excluded.
Age Factors↗
[An experimental study of the orthodontic force effect on internal remodeling of mandibular bone].
The role of mechanical stress in determining bone structure by influencing its cellular processes during remodeling has been discussed. But previous studies have not provided an adequate background of knowledge to explain the effect of orthodontic force in internal remodeling of the bones. This study was performed to determine the relationship between stress distribution induced by orthodontic force and alteration of internal remodeling in mandibular bone. Seven young adult mongrel dogs of unknown age were used as experimental animals. The bilateral lower 4th premolars were extracted. After 106 days, the 3rd premolars on the right side were moved distally by coil springs for 106 days. Twice pulse labels of tetracycline and calcein were performed to obtain histomorphometric parameters of cortical bones prior and posterior to tooth movement. With the use of microscopic plotting tool and minicomputer, the direction of haversian systems was reconstructed three-dimensionally. To make a comparison with the alteration of histomorphometric parameters and direction of Haversian systems, the principal stress distribution of mandibular bone caused by orthodontic force was obtained by means of 3-D finite element method analysis. Experimental results indicate as follows. 1. The osteoid seams number per unit area (OsAf) and the labeled surface per unit area (TcAf) increased significantly at both alveolar and basal bone region compared with control side. 2. The resorption cavities number per unit area, (Ar) increased significantly at alveolar bone region. But no significant changes were noted at basal bone region. 3. No significant differentiations were noted in mineral appositional rate (Mo) between any bone regions nor label timings. 4. There is large variance between the direction of Haversian systems and the maximal principal stress vector. But a significant alteration of the direction of Haversian systems was found in highly stressed and younger bone areas. From these findings, it can be speculated that, as a primary reaction of bone against stress, the optimum microscopic structural change took place in areas of bone which bore tension or pressure due to excess stress, at the same time the internal remodeling of bone was accelerated by increase of activation frequency (mu), accompanied with no increase of remodeling periods (sigma).
Animals↗
A CELL SYSTEM IN WHICH RATE AND AMOUNT OF PROTEIN SYNTHESIS ARE SEPARATELY CONTROLLED.
The mean cross-sectional area of Haversian systems in adult human ribs tends to be constant in the face of sevenfold changes in the rates at which these systems are made. This implies that different mechanisms control the total amount of cellular work in making Haversian systems and the rate at which this work is performed.
Adult↗
Structural changes of cortical bone in secondary hyperparathyroidism: replacement of lamellar bone by woven bone.
In femoral cortical bone of 16 uremic patients with long standing renal insufficiency an increased fraction of woven bone was found both in Haversian and in interstitial bone. Either partly resorbed Haversian systems were replaced by non lamellar woven bone or single Haversian systems showed partly well organized lamellar bone and partly disorganized non lamellar texture without signs of antecedent resorption. The replacement of lamellar bone by woven bone was measured morphometrically in undecalcified ground sections. Woven bone was defined by its lack of structural birefringence under polarized light. In advanced cases of secondary hyperparathyroidism more than 60% of cortical bone were composed of woven bone. The substitution of immature less organized woven bone for mature well orfanized lamellar bone has important implications for the biomechanical properties of the skeleton.
Adult↗
Young's moduli and shear moduli in cortical bone.
Young's modulus and shear modulus are determined for cortical bone from mammals and birds and for antler bone, using three-point bending at a range of span-to-depth ratios between 25 and 10. Young's modulus is obtained by extrapolating the values for the flexural modulus Eapp to infinite span-to-depth ratios. The shear modulus is obtained from the dependance of Eapp on this ratio. The main determinant for the mechanical properties is the mineral content. For mammalian bone the frequency of Haversian systems correlates negatively with stiffness and resistance to shear. However, because Haversian systems have a lower mineral content than laminar bone (the main component), material and structural determinants can not be separated at present. The ratio of Young's modulus to shear modulus is of the order of 20:1. This high value is discussed in terms of the Cook-Gordon theory of controlled crack propagation as well as in its significance for protecting hollow bones from failing upon local impact.
Animals↗
Some aspects of the system of Haversian canals in the diaphysary compact bone in man.
The general aspect of the network of Haversian canals was studied on tangential and radial sections from the diaphysary compact bone of the human long bones. The network-like aspect was much varied even in the same bone and at the same level from which the samples were obtained. No obvious differences were found between the studied bones or between the two limbs. Certain peculiarities of the canal system were noticed as regards the trajectory of canals, disposition and number of anastomoses, and the network aspect, depending on the region of the diaphysis, but especially on the depth.
Adult↗
The effect of chronic administration of trisodium nitrilotriacetate (Na3NTA) on the haversian remodelling system in dogs.
Trisodium nitrilotriacetate from the environment is reported to accumulate in bone. Two skeletally mature male littermate beagles were administered Na3NTA in a concentration of 2.5 mg/kg body weight in their drinking water for a period of 7 months. Rib biopsies were obtained from the dogs after fluorescent labelling before and at the end of the experimental period. Blood levels of zinc were measured at the same times. Twenty-two similar dogs from the same colony acted as controls. We noticed a decrease in radial closure rates and percent osteoid seams labelled between the experimental and the control animals which was statistically significant at the 0.05 level. The serum levels of iPTH and the bone levels of zinc showed no statistically significant difference. Accepting the fact that the treatment population was small and that the changes observed--although statistically significant--were minimal, it cannot be discounted that the exposure of these animals to Na3NTA for a longer period of time would not have had a more adverse effect on haversian bone remodelling activity.
Acetates↗
Tibial changes in experimental disuse osteoporosis in the monkey.
We studied the mechanical properties and structural changes in the monkey tibia with disuse osteoporosis and during subsequent recovery. Bone bending stiffness was evaluated in relationship to microscopic changes in cortical bone and Norland bone mineral analysis. Restraint in the semireclined position produced regional losses of bone most obviously in the anterior-proximal tibiae. Following 6 months of restraint, the greatest losses of bone mineral in the proximal tibiae ranged from 23% to 31%; the largest changes in bone stiffness ranged from 36% to 40%. Approximately 8 1/2 months of recovery were required for restoration of normal bending properties. However, even after 15 months of recovery, bone mineral content did not necessarily return to normal levels. Histologically, resorption cavities in cortical bone were seen within 1 month of restraint; by 2 1/2 months of restraint there were large resorption cavities subperiosteally, endosteally, and intracortically. After 15 months of recovery, the cortex consisted mainly of first-generation haversian systems. After 40 months, the cortex appeared normal with numerous secondary and tertiary generations of haversian systems.
Animals↗
[Histological study of species identification using bones].
OBJECTIVE: To explore the species identification methods of bone remain. METHODS: The compare between human bone and common animals bones was made with microscopic comparison methods. The sample was consisted of 77 slides including human, cattle, house, pig, goat, sheep, monkey, cat, rabbit, chicken, duck, pigeon, tortoise, frog, fish. RESULTS: The differences of the histological bone species were as follow: the thick of the outer and the inner circumferential lamellae, and the shape of interstitial lamellae, and the size of Haversian system, and the number of the circumferential lamellae, and the number of the lacunae of inner Haversian system. CONCLUSION: The histological characters of the bones can be used for species identification.
Animals↗
Study of the morphology and biomechanics of sacral fracture.
OBJECTIVE: To observe the morphological characteristics of sacral fracture under different impact loads. METHOD: Ten fresh pelvic specimens were loaded in dynamic or static state. A series of mechanical parameters including the pressure strain and velocity were recorded. Morphological characteristics were observed under scanning electron microscope. RESULTS: The form of sacral fracture was related to the impact energy. Under low energy impact loads, ilium fracture, acetabulum fracture and crista iliaca fracture were found. Under high energy impact loads, three types of sacral fracture occurred according to the classification of Denis: sacral ala fracture, Type I fracture; sacral foramen cataclasm fracture, Type II fracture; central vertebral canal fracture, Type III fracture. Nerve injury of one or two sides was involved in all three types of sacral fracture. The fracture mechanism of sacrum between the dynamic impact and static compression was significantly different. When the impact energy was above 25 J, sacral foramen cataclasm fracture occurred, involving nerve root injury. When it was below 20 J, ilium and sacral fracture was most likely to occur. When it was 20 approximately 25 J, Type I fracture would occur. While in the static test, most of the fracture belonged to ilium or acetabulum fracture. The cross section of sacrum was crackly and the bone board of Haversian system was brittle, which could lead to separation of bone boards and malposition of a few of cross bone boards. CONCLUSIONS: In dynamic state, sacrum fracture mostly belongs to Type I and Type II, and usually involves the nerve roots. Sacrum fracture is relevant to the microstructures, the distribution of the bone trabecula, the osseous lacuna and the Haversian system of sacrum. The fracture of ilium and acetabulum more frequently appears in static state, with slight wound of peripheral tissues.
Biomechanical Phenomena↗
Morphologic comparison of healing patterns in ethylene oxide-sterilized cortical allografts and untreated cortical autografts in the dog.
Full-thickness canine cortical allografts were harvested cleanly, sterilized with ethylene oxide, and stored at 22 degrees C. The sterilized allografts were incorporated into segmental, femoral fracture repairs and evaluated for 6 months. Allografts were compared with untreated cortical autografts, which also were incorporated into segmental, femoral-fracture repairs for 6 months. Sequential fluorochrome labeling at 8, 11, 21, and 24 weeks after surgery made it possible to evaluate retrospectively the time of new bone formation. Morphometric evaluations were made of the numbers of labeled haversian systems, the percentage of labeled bone, and the porosity of the bone. The cortical allografts had bone formation in the proximal and distal portions of the graft, with the greatest activity at 5 to 6 months after surgery. Activity in the center of the allograft was minimal. Cortical autografts had bone formation throughout the graft, with the greatest number of haversian systems labeled at 3 months after surgery. We concluded that cortical allografts heal and remodel more slowly and in a different sequence of events than do cortical autografts.
Animals↗
Differences in femoral compact bone tissue microscopic structure between adult cows (Bos taurus) and pigs (Sus scrofa domestica).
The purpose of this investigation was to study in detail compact bone tissue microscopic structure of adult cows and pigs with an emphasis to find an adequate key for the species identification. Altogether 18 femurs were analysed. Each of the bones was sectioned at the smallest breadth of their diaphysis. Specimens were prepared using standard histological equipment, producing thin sections approximately 80-100 mum thick. The qualitative differences between investigated species were examined in anterior, posterior, medial and lateral views of thin sections. The quantitative ones were counted using the specific computer software Scion Image. We measured the area, perimeter, minimal and maximal diameter of the Haversian canals, the Haversian systems and the vascular canals of primary osteons. After that a discriminant function analysis was used for the species identification. According to our results the basic structural pattern of femur diaphysis was primary vascular plexiform in both species. However, non-vascular bone tissue was identified in cows and resorption lacunae were found between the secondary osteons in pigs. The measured variables of the Haversian canals, the Haversian systems and the primary osteon's vascular canals were higher in most cases in cows. Classification functions for investigated species give a correct classification of 64.69% of cases. This percentage value can be increased by integrating conclusions from the qualitative analysis.
Animals↗
A topographic quantitative analysis of the post-natal bone formation in the auditory ossicles of the dog.
The amount and distribution of the post-natal bone deposition in the auditory ossicles and in the left tibia of dogs of varying ages were studied by means of alizarin labelling. The relative amount of fluorescent new-formed bone was expressed as a percentage ratio NB/(NB+PB) of new bone (NB) on the pre-existing bone (PB). The result was that the post-natal bone deposition (1) was larger in the tibia than in the incus, malleus and stapes; (2) significantly decreased with age both in the ossicles and in the tibia; (3) in the stapes it stopped at 3 months, while it was present in the tibia, incus and malleus even at 12 months. In the ossicles the post-natal bone deposition takes place both on the periosteal surfaces of the ossicles and on the internal surfaces of the haversian systems. The first process produces an appositional growth that stops in all three ossicles within the 1st month of post-natal life, the second one produces an internal growth that continues until the age of three months in the stapes, while in the incus and malleus it occurs in small amounts, even in the 12th month of life. In the ossicles all the new-formed bone tissue, periosteal and osteonic, is built up by primary bone (addition bone). In the tibia from 50 days of age the primary bone is gradually replaced by secondary haversian systems as a consequence of remodelling processes.
Age Factors↗
Appositional bone formation rates in the Beagle.
Measurements of haversian appositional bone formation rates were carried out on 400 haversian systems in 28-month-old standardized research colony-raised Beagles, using the midshaft of the 11th rib. The appositional bone formation rate was gradual and regular when the circumference of the outer tetracycline ring was more than 0.35 mm, but the regularity of the measured rate disappeared when the outer tetracycline ring circumference was less than 0.35 mm. Erroneous conclusions could be drawn from measurements of appositional bone formation rate in these animals if this fact were not taken into consideration, and we concluded that in pre- and postexperimental biopsy sections in the ribs of these animals, haversian systems with tetracycline ring circumferences above 0.35 mm must be measured in both situations if the differences in appositional bone formation rate are to be construed as being truly significant.
Animals↗