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At least 19 recordsLinked to original sources
PubMed1979

Age-related variations in cortical bone-remodeling measurements in male Beagles 10 to 26 months of age.

Age-related variations in bone-remodeling rates in the male Beagle were unknown. Variations were examined in 28 male Beagles whose ages were evenly distributed between 10 and 26 months. Results were analyzed by computer and regression lines for a best fit line for each determination were given; the 95% confidence limit for the best-fit line and the 95% confidence limits for the individual measurements were calculated. The results are graphically presented in this paper. There was a slight increase in total cortical area, although there was a decrease in the ratio of total-to-cortical area. Osteoid seams showed a frank decrease. Relatively little variation was found in circumference of osteoid seams and appositional rate. The number of resorption spaces decreased. There was a decrease in radial closure rate. Marked decreases were found in activation frequencies and bone formation rate. Increases were observed in osteon formation times and ratio of resorption to formation. The width of osteoid seams and the percentage of systems labeled decreased slightly. As a result of these experiments concerning variations in bone-remodeling activity carried out on Beagles (using the same dogs as their own controls), it was concluded that results obtained should be compared with the expected age-related activity of bone remodeling and not with the initial preexperimental biopsy results.

Aging↗
PubMed1979

Studies on bone-remodeling rates on the Beagle: A comparison between similar biopsy sites on different ribs.

Two male littermate standardized colony-raised Beagles were studied to find out whether there was any statistically significant difference in the measurements of bone-remodeling determinations at similar sites on different ribs of the animal. Tetracycline fluorescent-labeling studies were performed on these animals, the midportion of the proximal, midshaft, and distal thirds being sampled from the 5th, 7th, 9th, and 11th ribs. Statistical analysis of the findings indicates that there is no significant difference in bone-remodeling activity between similar sites on alternate ribs. This fact permits studies on bone-remodeling activity in an animal to be done in which the same animal is used as its own control and in which more than two experimental biopsy samples are required.

Animals↗
PubMed1977

Bone remodeling in pathologic conditions. A scanning electron microscopic study.

Bone remodeling in pathologic conditions was studied with the scanning electron microscope (SEM). Benign and malignant ossification were examined in cases of myositis ossificans, ossifying fibroma, osteoid osteoma, and osteosarcoma, Resorption of bone due to invasion by non-ossifying tumors was found in cases of squamous cell carcinoma, adenocarcinoma, ameloblastoma, and multiple myeloma. Bone formation due to excessive production of growth hormone was studied in a case of acromegaly. Resorption of bone due to pathologic processes resembled the pattern found in surfaces which were undergoing resorption by osteoclasts. Lamelar-cortical bone formation in acromegally was similar in nature to normal bone. The deformities were rleated to the excessive continuous osteogenesis that occurs in these instances. Neoplastic ossification was characterized by calcifying globules, the diameters of which ranged from 1 to 3 micron. The surfaces of these globules were constructed of minute calcospherites with diameters ranging from 0.1 to 0.3 micron. It is suggested that the pattern of globular calcification is similar to the type that was found with the SEM in fetal bone and cartilage, during healing of fractured bone, and also with the TEM in normal and pathologic calcification.

Acromegaly↗
PubMed1976

The actions of parathyroid hormone on bone: relation to bone remodeling and turnover, calcium homeostasis, and metabolic bone diseases. II. PTH and bone cells: bone turnover and plasma calcium regulation.

Kinetic and morphologic studies in patients with parathyroid disease, and a wide variety of studies in experimental animals indicate that one major effect of PTH is to increase the proliferation of osteoprogenitor cells into osteoclasts and so to increase bone turnover. PTH stimulates bone cells by increasing cell membrane permeability to calcium and consequently increasing calcium influx and by activating membrane-bound adenyl-cyclase. It is likely that the former event precedes the latter and that calcium is the second messenger and cyclic AMP the third messenger. PTH increases the production by bone cells of lactate, citric and carbonic acids, lysosomal enzymes, collagenase, and hyaluronic acid, some or all of which are concerned in the mechanism of bone resorption. With the exception of lactate which probably comes mainly from osteocytes, the increase in metabolic activity is largely due to the increase in the number of osteoclasts. There is also ultrastructural, biochemical, and biophysical evidence that PTH stimulates existing osteoclasts, but this most likely represents the transformation of inactive cells into an active state, and is a transient and nonsustainable effect. As yet, there is no evidence that either increased osteoprogenitor cell proliferation or increased osteoclast activity is mediated by adenyl-cyclase activation. PTH also acts on the deep osteocyte to cause rapid mobilization of calcium from the zone of hypomineralized metabolically active perilacunar bone. This effect is mediated by adenyl-cyclase activation and is preceded by a slight fall in plasma calcium probably due to the movement of calcium into bone cells. The function of this rapid hypercalcemic response to PTH is correct errors in the prevailing steady-state level of plasma calcium...

Animals↗
PubMed1979

Differences in intracortical bone remodeling in three aboriginal American populations: possible dietary factors.

Cross sections of intracortical bone revealed differences among three early American populations--Eskimo, Arikara, and Pueblo--in the frequency of a form of remodeling called, here, type II. This remodeling appears to occur exclusively within the walls of haversian canals of well-mineralized osteons. The populations are known to have differed in their nutrition. The Eskimo, with a high-protein diet, exhibited the most frequent type II remodeling, whereas the Pueblo, with a low-protein diet, showed the least. Type II remodeling probably reflects the physiological state of the group. Variation in frequency of classic intracortical bone remodeling was not apparent.

Adult↗
PubMed1977

Bone remodeling in periodontal lesions.

This study was designed to investigate sites of major alveolar bone formation as a result of resorption of the interdental crest in periodontal lesions. Bone samples were taken from twelve patients requiring surgery as part of their periodontal treatment. Tetracycline was used in all cases to label bone recently formed. The selected areas were periodontal pockets ranging in depth from 6 to 8 mm. The bone deformities were of crater-form configuration. The buccal and lingual plates were removed. Later, the dehydrated speciemns were embedded in bioplastic and cut to sections 70 mu thick. Controls were healthy pieces of bone taken from the same patient in unaffected areas. Yellow fluorescent tetracycline labeling was observed in both periosteal and trabecular bone. In the trabecular bone, labeling was exhibited in the lamella of some Haversian systems, away form the bone resorption. There was a direct relationship between bone resorption and bone apposition as seen by the presence of tetracycline in the buccal and lingual alveolar plates. Controls showed only minimal labeling. The results of this study have posed the question as to whether inflammation could be the stimulus in the reactivation of osteocytes or bone formation, in the buccal and lingual walls of the periodontal lesions.

Alveolar Process↗
PubMed1977

Bone remodeling and calcium metabolism: a correlated histomorphometric, calcium kinetic, and biochemical study in patients with osteoporosis and Paget's Disease.

The extent to which histomorphometric analysis of bone biopsies correlates with Ca kinetic and biochemical parameters to reflect true bone formation and resorption in adult man remains an unsolved issue. Two groups of patients with either low (osteoporosis), (n = 15) or high (Paget's disease, n = 6) bone turnover were studied before and after sodium fluoride (NaF) and diphosphonate (EHDP) treatment, respectively. Histomorphometry of iliac crest biopsies permitted precise quantitation of the osteoblast layers (SVab), osteoid seams (SVos), the number of osteoclasts (NAocl) and the Howship's lacunae (SVhl). These determinations were correlated with serum alkaline phosphatase (aPh), urinary hydroxyproline (HyPro), Ca accretion rate (Vo+), and Ca mobilization rate (Vo-). In both patient groups bone formation indices were significantly correlated: SVob/Vo+, r = 0.85; SVos/Vo+, r = 0.83; and aPh/Vo+, r = 0.97. Provided that bone matrix formation and mineralization progess at the same rate, bone formation may be assessed by measuring either aPh, Vo+, SVob, or SVos. From these correlations it is not possible to draw any conclusions regarding the absolute "true" value of bone formation, be it in terms of Ca kinetics, alkaline phosphatase, or histomorphometry. However, since Vo+ retains its proportionality to all the other bone formation parameters tested, the so-called "slow exchange," which refers to pure physicochemical Ca exchange processes in the bone mineral, does not perturb Vo+ in an unsystematic way. Vo+ as well as aPh and histomorphometric indices are thus reliable, though not absolute indices of bone formation. Bone resorption indices correlated less well than bone formation indices: NAocl/Vo-, r = 0.68 and SVhl/Vo-, r = 0.63 with both groups. In the osteoporotic group, a negative correlation existed between the empty Howship's lacunae SVhe and Vo+, r = -0.62. Consequently, the overall extent of Howship's lacunae SVhl is influenced both by bone resorption and bone formation. On the other hand, the best correlation of HyPro was with the sum of Vo+ and Vo-, r = 0.97, confirming that HyPro is a sensitive index for the change of bone turnover.

Adult↗
PubMed1979

Influence of alpha-MSH and ACTH on cortical bone remodelling in hypophysectomized rats.

Hypophysectomy increases both periosteal resorption and endosteal apposition along the femur diaphysis in rat. Administration of alpha-MSH decreased the periosteal resorption but had no effect on the endosteal apposition. ACTH had only minor effects on the endosteum. Thus, alpha-MSH and ACTH, in the doses used, have different effects on cortical bone in rat. The effect of alpha-MSH on cortical bone could be an effect of the hormone alone or by its stimulation of other factors.

Adrenocorticotropic Hormone↗
PubMed1975

Cyclic AMP and cyclic GMP: mediators of the mechanical effects on bone remodeling.

Compressive forces of physiological magnitude (60 grams per square centimeter) reduce the adenosine 3',5'-monophosphate and guanosine 3',5'-monophosphate content of the epiphyses of tibiae from 16-day-old chick embryos. An equivalent hydrostatic pressure applied directly to cells isolated from this tissue also affects cyclic nucleotide accumulation. The tissue response is uniform throughout the epiphysis, whereas the cell response varies according to the area of origin.

Animals↗
PubMed1975

Effects of dichloromethylene diphosphonate, ethane-1-hydroxy-1,1-diphosphonate, and rickets in rats.

This study compared bone remodeling, bone mineralization, and parathyroid hormone secretion in rats treated with ethane-1-hydroxy-1,1-diphosphonate (EHDP) or dichloromethylene diphosphonate (Cl2MDP). The results were compared with findings in rachitic and control rats. In addition, calcification was induced in the skin by administration of lead acetate intravenously and polymyxin B subcutaneously; the efficacies of EHDP and Cl2MDP in preventing the calcific plaque were compared. Both the serum biochemical values and the morphologic findings indicate that Cl2MDP and EHDP influence bone and mineral metabolism differently. Even with the relatively large doses used in this study, Cl2MDP had a minor or no effect while EHDP had a marked effect that, in general, is undersirable. EHDP caused increase in circulating immunoreactive parathyroid hormone to levels greater than those in rachitic rats. Both diphosphonates appear to have a similar effect on the ectopic mineralization produced by calciphylaxis, suggesting that Cl2MDP may be the agent of choice in this problem because the undersirable side-effects would be avoided.

Acetates↗
PubMed1979

[Study on remodelling of bone grafts--an application of nuclear medicine (author's transl)].

The remodelling of bone grafts depends to a large extent upon the type of graft and the condition of the recipient site. We applied 99mTc-phosphate scintigraphy in a follow-up study on cases treated by bone grafting, and quantitative analysis of the scintigram by computer to make clear the difference of remodelling time or the process of acceptance between a cancellous and a cortical bone grafting or due to various graft and conditions. The result revealed that the grafted bones which were smoothly adapted for subsequent growths or functions could restore normal accumulation ratios by 36 months after the grafting. When the cancellous bone was grafted to grafting beds with good conditions such as osteotomy site in the cases with coxarthrosis deformans or congenital dislocation of the hip, it could attain the quickest recovery of the normal accumulation ratio. The next quickest recovery of accumulation ratio was attained by grafting the cancellous bone to the grafting beds with poor conditions such as osteomyelitis, pseudoarthrosis, and bone tumor. The third best accumulation ratio could be attained when the cortical bone was grafted to grafting beds with good conditions, while the slowest recovery to normal accumulation ratio was noted when the cortical bone was grafted to grafting beds with poor conditions.

Adolescent↗