Endosteal Bone Surfaces Research Articles

Microdistribution of 237Np in the skeleton of female rats.

237Np nitrate was injected intravenously into 4-week-old (young) and 10-12-week-old (adult) female albino Sprague-Dawley rats. The amounts given were 52 (young), 5.2 (adult) and 26 kBq kg-1 body weight (adult). The microscopic distribution in the femur and the lumbar vertebrae was studied. Initially, neptunium was distributed uniformly on periosteal and endosteal bone surfaces, and additionally, activity was found in the vascular canals of hard tissue. Dose-rates and cumulative doses were found to increase from marrow to hard tissue, and periosteal and endosteal surfaces, the highest levels being found in the spongy bone of the distal femoral metaphysis. Initially, the highest dose rates were found in hard tissue of the distal femoral metaphysis (27 mGy per day per injected activity of 37 kBq kg-1), whereas periosteal bone surfaces showed levels of 65 mGy per day in all bone regions. One year later the normalized dose rates on the surfaces decreased to 10 or 15 mGy per day. After 1 year the cumulative doses in the 0-10 microns marrow layer on the endosteal bone surfaces were 8 (52 kBq kg-1, young), 2.1 (5.2 kBq kg-1, adult) and 8.7 Gy (26 kBq kg-1, adult). The microdosimetric findings were compared with the macroscopical doses of the whole skeleton.

Bone cancer risk estimates.

Due to confusion between endosteal (bone surface) dose and average skeletal dose, ICRP 60 has substantially overestimated the risk of radiogenic bone cancer. This confusion apparently stems from an incorrect reading of the BEIR IV report, which does not clearly draw this distinction. It should also be noted that what appear to be summary numerical risk estimates for bone sarcoma induction in BEIR IV and BEIR V refer only to average skeletal dose as calculated for 224Ra.

Alveolar bone resorption process in molar tooth region in calcium-deficient rats

The present study was carried out to investigate the alveolar bone resorption in the molar tooth region in the rats fed a low calcium diet. Male Wistar rats (70-85g in body weight) were either fed a low calcium diet (0.05% Ca, 0.35% P) or a control diet (0.5% Ca, 0.35% P) by using a pair feeding technique. The rats were sacrificed at intervals of 3, 6, 9 and 20 days during the experimental period. Contact microradiograph of the second molar region of the mandible showed that the cancellus bone as well as the endosteal surface of the cortical bone were progressively resorbed soon after the start of low calcium feeding. At day 9, the amount of bone was reduced to about half of the control rats and 80% of the bone was diminished at day 20. In spite of the severe bone resorption, the alveolar bone proper that surrounds the molar sockets and a few cancellus bone were seen remaining and the occlusal function of the molar tooth seemed to be maintained. These results suggest that the alveolar bone quickly responded to the low calcium diet resulting in bone resorption and that the bone in the supporting tissues of the molar tooth seems to be not affected by the calcium deficiency.

Effects of estrogen on the proliferation and differentiation of osteogenic cells during the early stage of medullary bone formation in cultured quail bones

Quail bone fragments cultured in the medium containing 17β estradiol (E2) were examined morphologically. On the endosteal bone surface of bones cultured in serum-containing medium, preosteoblasts were observed and labeled by3H-thymidine after 24 h of culturing. After 48 h of culturing, medullary bones occasionally appeared along the endosteal surface, and their bone surfaces were covered with labeled osteoblasts. These osteoblasts were frequently found when added E2. On the endosteal bone surface of cultured bones in the serum-free medium alone, bone lining cells were observed and not labeled throughout the culture period. On the endosteal bone surface of bones cultured in the serum-free medium containing E2, labeled preosteoblasts were seen after 24 and 48 h of culturing. However, osteoblasts did not appear. These findings suggest that estrogen acts directly on the proliferation and differentiation of osteogenic cells.

Immunoelectron microscopic demonstration of estrogen receptors in osteogenic cells of Japanese quail

The localization of estrogen receptors (ERs) in osteogenic cells was immunoelectron microscopically examined in the femurs of female and estrogen-treated male Japanese quail. An electron dense reaction product showing ER localization was observed in the nuclei of osteoblasts and immature osteocytes in the medullary bone of the female quail. However, reaction product was not seen in the osteoclasts. On the endosteal bone surface of male quail, nuclear reaction product was detected in bone lining cells. After 24 h of estrogen treatment, reaction product was observed in the nuclei of preosteoblasts on the endosteal bone surface. After 48 h, the medullary bone partly appeared along the endosteal surface. Nuclear reaction product was seen in osteoblasts on the medullary bone surface.

Estrogen target cells during the early stage of medullary bone osteogenesis: Immunohistochemical detection of estrogen receptors in osteogenic cells of estrogen-treated male Japanese quail

The localization of estrogen receptors (ER) in osteogenic cells during the early stage of medullary bone osteogenesis was studied immunohistochemically in the femurs of estrogen-treated male Japanese quail. Alkaline phosphatase (ALP) activity was used as a marker for osteogenic cells. ER immunostaining was observed in the nuclei of weak ALP-positive bone lining cells on the endosteal bone surface of nontreated birds. After 24 hours of estrogen treatment, nuclear immunostaining was detected in ALP-positive preosteoblasts on the endosteal bone surface. After 48 hours, the medullary bone appeared to some degree along the endosteal surface. ER immunostaining was observed in the nuclei of ALP-positive osteoblasts on the medullary bone surface. This study demonstrates that ER are present in osteogenic cells, and suggests that estrogen directly acts on medullary bone osteogenesis.

Microdistribution of239Pu in the Rat Skeleton

Sixty-day-old male and female rats were injected intravenously with one of three doses of monomeric 239Pu (1.11, 11.1 and 111 kBq kg-1 body weight) and were killed 1, 7, 14 or 32 days after injection. The macroscopic distribution in the skeleton as well as the microscopic distribution in the distal femur and the lumbar vertebra were studied. In general, no significant differences between the two sexes and the normalized three dose levels were found. The concentrations and dose-rates in hard tissue, marrow and near bone surfaces were lowest in the femur diaphysis and highest in the distal femur metaphysis. In each bone region the dose-rate increased in the order marrow, hard tissue, periosteal and endosteal bone surfaces. The initial dose-rates on the endosteal bone surfaces ranged from 130 mGy d-1 (femur diaphysis) up to 300 mGy d-1 (distal femur metaphysis), corresponding to an average cumulative monthly dose of 2.2 Gy (femur diaphysis) and 7 Gy (distal femur metaphysis) normalized to an injected dose of 37 kBq kg-1 body weight. After the injection of 111 kBq kg-1 body weight radiation, induced morphological changes occur to the distal femur metaphysis 32 days after injection.

Immunohistochemical Localization of the Matrix Glycoproteins-Tenascin and the ED-sequence-containing Form of Cellular Fibronectin—in Human Permanent Teeth and Periodontal Ligament

The expression of two matrix glycoproteins, tenascin and cellular fibronectin (cFN), has been studied in fully developed human permanent teeth, periodontal ligament, and alveolar bone, in both frozen and paraffin-processed material. Polyclonal antibodies to tenascin and a monoclonal antibody recognizing the ED sequence specific to at least some forms of cFN were used. Staining for both tenascin and cFN was positive in the dental pulp, odontoblastic layer, cementoblast-pre-cementum zone, and on the periosteal as well as endosteal surfaces of the alveolar bone. In the periodontal ligament, cFN was evenly distributed, whereas tenascin was accumulated in the attachment zones. Pre-dentin stained for tenascin but not for cFN. Mineralized dentin and cementum were tenascin- and cFN-negative. The relative staining intensity for tenascin was greater than that for cFN in the cementoblast-pre-cementum layer and in the attachment zones of the periodontal ligament, whereas cFN stained more intensely in the pulp. In frozen material, antigenicities were well-preserved. Paraffin processing facilitated precise recognition of tissue morphology, but the antigenicity of cFN was lost. The co-expression of tenascin and cFN in the dental pulp, cementogenic zone, and on the surfaces of the alveolar bone may reflect the ability of the cells to deposit mineralized tissue matrices. The pronounced expression of tenascin in the interfaces between mineralized and non-mineralized tissues suggests that it is functionally associated with mechanical stress and may thus have at least two distinct functions. The relative amounts of the two matrix glycoproteins may contribute to regulation of tissue structure.

Distribution of trace levels of therapeutic gallium in bone as mapped by synchrotron x-ray microscopy.

Gallium nitrate, a drug that inhibits calcium release from bone, has been proven a safe and effective treatment for the accelerated bone resorption associated with cancer. Though bone is a target organ for gallium, the kinetics, sites, and effects of gallium accumulation in bone are not known. We have used synchrotron x-ray microscopy to map the distribution of trace levels of gallium in bone. After short-term in vivo administration of gallium nitrate to rats, trace (nanogram) amounts of gallium preferentially localized to the metabolically active regions in the metaphysis as well as the endosteal and periosteal surfaces of diaphyseal bone, regions where new bone formation and modeling were occurring. The amounts measured were well below the levels known to be cytotoxic. Iron and zinc, trace elements normally found in bone, were decreased in amount after in vivo administration of gallium. These studies represent a first step toward understanding the mechanism(s) of action of gallium in bone by suggesting the possible cellular, structural, and elemental "targets" of gallium.

Structural consequences of endosteal metastatic lesions in long bones.

Lytic metastatic lesions from breast, prostate, and other cancers often develop on the endosteal surface of a long bone without penetrating the cortical wall. Current clinical guidelines for determining the fracture risk associated with these endosteal defects do not account for the structural consequences of the lesion. We undertook a combined experimental and analytical study of the structural consequences of the lesions with the ultimate goal of providing improved fracture risk guidelines. Endosteal defects of variable length and involving a variable amount of the cortical wall were created with an expanding reamer in canine femurs. The contralateral femur served as a control. The femurs were tested to failure in four point bending. The geometry of the experimental defects was determined from radiographs and CT. Finite element models of the canine femurs were then used to examine geometric and material parameters in both four point bending and in torsion. The experimental data demonstrate a linear relation between bone strength and amount of cortical wall remaining: % intact strength = 99.6 x remaining wall thickness - 2.0, R2 = 0.769, standard deviation of regression = 11.57. Four of five data points from the linear finite element models were within the 95% confidence intervals for the experimental data. Experimental and finite element data suggest that the minimum wall thickness is the most critical geometric parameter for predicting the structural consequences of endosteal defects. The length of the defect along the bones' long axis has little effect on bone strength. The anelastic behavior of bone does not need to be represented in finite element models of simple endosteal defects because the defects do not cause significant stress concentrations. However, reduction in the modulus of bone along the border of a defect (due to osteolytic changes) can significantly reduce bone strength. These results indicate that the minimum wall thickness should be determined when clinically evaluating an endosteal defect. The results also suggest that information on bone porosity around metastatic lesions should be considered when making estimates of bone strength.

The metabolism and immunology of bone

Many cells and their cytokines produce a significant effect on bone metabolism. Bone matrix synthesis is a function of the osteoblast (Fig 1), influenced directly by numerous local and systemic factors (Tables 1 and 2). Locally synthesized factors such as SGF, BMP, and BDGF may be particularly important in stimulating new bone formation at sites of bone resorption or following bony injury. Of the systemic factors, GH; somatomedin C (IGF-1); high concentrations of insulin, testosterone, PDGF and TGF beta; and low concentrations of PGE 2 and IL-1 appear to stimulate bone formation in vitro. These latter factors may be more important in maintaining skeletal growth and bone mass. Bone resorption by osteoclasts (Figs 2 and 3) is also controlled by the osteoblast, as this cell produces a leukotriene-dependent polypeptide that stimulates osteoclastic bone resorption. Osteoblasts cover the periosteal and endosteal bonesurfaces and limit exposure of the underlying bone to osteoclasts. PTH, vitamin D, PGE 2, and other systemic factors interact directly with the osteoblast, not the osteoclast. Surface receptor binding of PTH increases intracellular cAMP and calcium and results in release of the factor that stimulates osteoclastic bone resorption. PGE 2 induces osteoblasts to activate osteoclasts and is a major controlling factor in bone metabolism; the osteoblast produces PGE 2, which can then modify osteoblastic function by positive feedback. Although low concentrations of PGE 2 stimulate bone formation, higher concentrations promote osteoblast-mediated bone resorption. Furthermore, many of the systemic factors stimulate bone resorption via a PGE 2-associated mechanism. Immune cytokines also appear to exert a profound influence on bone metabolism. INF-gamma inhibits osteoclastic resorption, whereas IL-1, TNF, and LT strongly stimulate bone resorption. However, low concentrations of IL-1 paradoxically result in stimulation of bone formation. These cytokines, particularly in various combinations, may prove extremely important in understanding and treating the bone loss associated with malignancies, osteoporosis, and rheumatoid arthritis.

The histochemical localization of acid phosphatase activity in BMU

In order to clarify the coupling mechanism (or phenomena) of the bone resorption-formation in the remodeling process, this study was attempted to observe the histochemical location of acid phosphatase (ACPase) and tartrate-resistant ACPase (TRACPase) activity of the newly formed cement lines and the mononuclear cells in BMU (basic multicellular unit) using JB-4 embedding technique for the demonstration of ACPase and TRACPase activity on the tibial metaphysis of rat. The ACPase activity could principally be observed both at the sites where the onset of the newly cement line formation of the trabecular bone and the endosteal bone surfaces, and the resorbed bone surfaces. However, the ACPase reactive cement line was never observed at the erosion zone of the tibial metaphysis, where the osteoblastic bone formation does not occur. Other than osteoclasts and cement lines, the ACPase activity was also observed either in the mononuclear cells closely located to the ACPase positive resorbed bone surfaces or the osteocytes near the osteoclasts. They were also positive for the TRACPase reaction. It was concluded that the active osteoclasts are moving on the bone surface as secreting ACPase to form the cement line, which may influence to induce osteoblasts from adjacent preosteoblasts. It was also suggested that the mononuclear cells and the osteocytes may also relate to the bone remodeling.

The bone lining cell: a distinct phenotype?

It is argued that the flat cells that line nonremodeling endosteal bone surfaces are a distinct phenotype. These cells have a distinct morphology and they most likely have important functional roles in skeletal physiology, metabolism, and remodeling. For these reasons this cell seems deserving of a proper name. The name bone lining cell seems to have gained some acceptance but there will be continued confusion as long as skeletologists use this same term to generically describe cells that line bone surfaces, regardless of their actual identity.

Effects of Antimetabolites and Physical Modification on Endosteal and Endothelial Zeta-Potentials

The endosteal surface of long bones of dogs prepared for streaming potential measurements was shown by Feulgen and PAS reactions to be heterogenous in composition. FDA-PI treatment showed that most of the cells remaining on the endosteal surface were living. Streaming potentials of the endosteal surface of bones and the luminal surface of arteries of dogs were measured in 0.01 M HEPES, pH 7.4 in 5.2% glucose before and after treatment with KCN, DNP, glutaraldehyde, or heparin, and used to calculate ξ-potentials. KCN, DNP and glutaraldehyde significantly altered ξ-potentials of bones whereas only DNP and heparin significantly changed the ξ-potentials of arteries. When the relative amount of endosteal surface of bone composed of exposed bone matrix was increased by drilling the ξ-potentials also increased. The results indicate that: a) both cellular and non-cellular elements contribute to the surface charge of endosteal bone, and b) the heterogenous endosteal bone surface and the cellular luminal arterial s...

Effects of pH on the Zeta-Potentials of Bone in Vitro

Zeta-potentials of bone in vitro were determined at pH 3, 4, 5, 6, 7, 8, 9, and 10 or in the reverse order with two different buffer series before and after deep-freeze storage (−80° C) in 0.01 M HEPES (pH 7.4) containing 5.2% (W/V) glucose. The buffer series used, the pH sequence, prestorage subjection to a pH sequence, and storage itself all proved to be important influences in determining the ξ-potential characteristics of endosteal bone surface even though no isoelectric point was found

A scanning electron-microscopic study of femoral bone surfaces from castrate rats treated with dichloromethylene biphosphonate.

This study compared SEM appearances of endosteal and periosteal surfaces of anorganic femoral diaphyses from three groups of adult male rats: (1) control; (2) castrate (osteoporotic), and (3) castrate + injections of dichloromethylene biphosphonate (Cl2 entrances; (2) area of vascular canal entrances; (3) number of osteoblast lacunae, and (4) percent area of bone surface types. Endosteal surfaces from untreated osteoporotic rats had significantly more osteoblast lacunae, larger vascular canal entrances, and less resting surface than those of the other groups. There were no differences in endosteal surfaces between controls and Cl2MBP-treated castrates. Periosteal surfaces demonstrated no significant differences in percent area of bone surface types between groups, untreated castrates had more osteoblast lacunae than other groups, and vascular canal entrances were smaller in castrate groups than in controls. Castrates treated with Cl2MBP had significantly fewer periosteal vascular canal entrances, and many canal entrances and osteoblast lacunae appeared to be plugged with mineral deposits when compared with the other groups. The results indicate that Cl2MBP treatment prevented endosteal bone surface changes that occurred with castration osteoporosis, and may have disrupted normal vascularization on periosteal surfaces.

Study of the localization of [3H]bovine parathyroid hormone in bone by light microscope autoradiography.

Bovine parathyroid hormone labeled with tritium on the methionine residues by [3H]methyl exchange ([3H]bPTH) was administered intravenously to 35-day-old mice and localized in tissues by light microscope autoradiography. After 10 min most of the [3H]bPTH had been taken up from plasma. In the kidney and liver, radioactivity was not displaced by simultaneous administration of unlabeled bPTH, and was as intense after giving oxidized [3H]bPTH ([3H]ox bPTH) as [3H]bPTH, suggesting that binding was largely associated with nonspecific processes. In long bones, [3H]bPTH was bound to osteoblasts and preosteoblasts lining the endosteal and periosteal surfaces of compact bone. In the area of the growth-plate there was intense labeling on new endochondrial bone, and on hypertrophic chondrocytes in the region of calcification. There was little labeling in marrow and, in contrast to other tissues, much reduced binding was seen when a large excess of unlabeled parathyroid hormone was administered together with [3H]bPTH, or when [3H]ox bPTH was given. It is concluded that binding of parathyroid hormone to cells in bone is largely specific, and that the hormone has a function in cartilage which relates to the differentiation and calcification of chondrocytes of the growth-plate that occurs prior to its replacement by new bone tissue.

Chemotactic activity of the gamma-carboxyglutamic acid containing protein in bone.

We have found that the gamma-carboxyglutamic acid (GLA)-containing protein from bone (BGP, osteocalcin) has chemotactic activity in vitro for a number of cells which are found adjacent to endosteal bone surfaces in vivo. Using the Boyden chamber technique for measuring cell chemotaxis in vitro, we have shown that BGP is chemotactic for cultured human breast cancer cells, human and mouse monocytes, and for cultured rat osteosarcoma cells which have the characteristics of osteoblasts. The migration of these cells in response to BGP is undirectional and not due to spontaneous or random migration. A synthetic peptide (Phe-Tyr-Gly-Pro-Val), which is identical to the carboxy-terminal peptide cleaved from BGP when digested by trypsin, is also chemotactic for the same cells. BGP retains its chemotactic activity after conversion of the gamma-carboxyglutamic acid residues to glutamic acid, indicating that this biological effect requires neither gamma-carboxyglutamate nor the ability of BGP to bind calcium. Since BGP is released from bone during states of increased bone turnover, it is possible that this chemotactic effect of the protein may be a mechanism for recruitment of these cells to sites of active bone remodeling.

Histometric evaluation of interproximal bone responses to electrosurgical mucoperiosteal incisions in dogs

The periosteal and endosteal interproximal bone remodeling activity following clinically simulated blade and electrosurgical mucoperiosteal incisions was investigated by histologic and morphometric analyses. Undecalcified histologic sections were prepared and evaluated using standard bone morphometric techniques. Periosteal and endosteal bone surfaces subjacent to incisions were examined and the percentages of forming, resorbing, and quiescent surfaces, and the number of osteoclasts per millimeter of bone surface, were calculated. Based on indices of bone remodeling activity, the potentials for activation of interproximal bone remodeling by clinically appropriate blade and electrosurgery incisions in dogs appear to be similar.

Properties of osteoblast-like cells isolated from the cortical endosteal bone surface of adult rabbits.

The purpose of the present study was to isolate cells from the cortical endosteal bone surface of adult rabbits and characterize some properties of these cells in vitro. Following removal of the marrow from the medullary cavity of long bones, the cells lining the cortical endosteal bone surface were obtained by enzymatic digestion using 0.1% crude collagenase. These cells were examined immediately after isolation or following their growth for 8–10 days in primary culture. Freshly isolated cells contained 7–10 times more alkaline phosphatase (AP) than acid phosphatase activity. This AP activity was extremely heat labile (incubation at 58°C caused >90% loss of enzyme activity within 15 min) and significantly more sensitive to inhibition by levamisole and L-homoarginine than L-phenylalanine. Synthetic bPTH-(1–34) [1–100 ng/ml], native bPTH-(1–84) [1 U/ml] and prostaglandin E2 [1–10 µg/ml] all caused a significant accumulation of cAMP in cultured endosteal bone cells. In contrast, neither salmon calcitonin (1 U/ml) nor porcine insulin (10–1000 ng/ml) stimulated an increase in cAMP. These results suggest that cells isolated from the cortical endosteal bone surface of adult rabbits are osteoblasts or osteoblast-like. These cells retain their ability to respond in a specific manner to bone-seeking hormones following their growth in culture. Cortical endosteal bone cells isolated from rabbits of different ages, physiologic or pathologic conditions can be used to assess the changes in bone cell function and responsiveness which may accompany senescence or development of adult metabolic bone disease.