bluuebunny/crossref_metadata_2025 huggingface dataset:
Multinucleated cells elicited in response to implants of devitalized bone particles possess receptors for calcitonin
Authors: Goldring Steven R. , Roelke Merrilee , Glowacki Julie
Published: February 2010

The introduction into soft tissues of particulate materials resistant to digestion results in the induction of a “foreign-body giant-cell reaction.” We have examined the relation between osteoclasts and foreign-body giant cells by comparing the tissue responses elicited by subcutaneous implants of devitalized, mineral-containing bone particles (BP), nonresorbable plastics such as polymethylmethacrylate (PMMA), or both. Implantation of BP results in the recruitment of multinucleated cells with features of in osso osteoclasts including tartrate-resistant acid phosphatase activity, contact-mediated resorption of BP, membrane specializations (ruffled borders and clear zones), and inhibition of resorption by calcitonin treatment of animals. In the present study, an autoradiographic technique employing 125I-salmon calcitonin was used to demonstrate the presence of receptors for this hormone on multinucleated cells from BP implants. In contrast, outgrowth cells from PMMA implants lacked calcitonin receptors. Demonstration of features of the osteoclastic phenotype in multinucleated cells elicited in response to BP supports the hypothesis that the mineralized matrix of bone may be a requirement for acquisition of the osteoclast phenotype.
Static and tetracycline-based bone histomorphometric data from 34 normal postmenopausal females
Authors: Dr. Recker Robert R. , Kimmel Donald B. , Parfitt Michael A. , Davies Michael K. , Keshawarz Naser , Hinders Sharilyn
Published: February 2010

Transilial bone biopsies were obtained from 34 healthy postmenopausal women following in vivo fluorochrome labeling. Stained and unstained undecalcified sections were evaluated using a Merz grid. Standard histomorphometric data from cancellous bone tissue were collected and the results were evaluated and presented as variables commonly used in bone histomorphometry. The normal ranges, medians, means, and standard deviations for the group of 34 are presented in tabular form for structural, surface, basic dynamic, and derived dynamic data. Similar data for individuals grouped by ages 45–54, 55–64, and 65–74 are also presented. Secular trends for the whole group are evaluated. The structural and surface data are not much different from previous reports of sudden-death accident victims, when methodologic differences are considered. The mineral apposition rate (MAR) was 0.53 ± 0.08 μm/day, similar to previous reports in cancellous bone, but one-third less than in cortical bone. MAR showed a marked decline with age. In contrast, the extent of tetracycline-labeled surfaces varied widely without a secular trend. Double-label surface (dLS/BS) ranged from 0.5 to 8.0% and single-label surface (sLS/BS), from 0.5 to 10.5%. Mineralizing osteoid surface (MS/OS) varied from 2 to 64%. Using only double-label surface to represent mineralizing surface, volumebased bone formation rate (BFR/BV) ranged from 0.7 to 28%/yr, and the remodeling period (Rm.P) varied from 0.28 to 4.5 years. Calculations using other representations of mineralizing surface [double plus one-half single label (MS/BS″); all label (MS/BS′)] are also presented. These bone histomorphometric data are important because: (1) they come from a cohort of living subjects that was recruited solely for the purpose of establishing normal bone histomorphometry; (2) they represent the age range of patients with postmenopausal osteoporosis; and (3) they markedly expand the bone histomorphometric database of healthy persons given in vivo fluorochrome labeling prior to transilial biopsy.
Interaction of calcium nutrition and physical activity on bone mass in young women
Authors: Kanders Bonnie , Dempster David W. , Lindsay Robert
Published: February 2010

We have examined the relationships among calcium intake, mechanical stress (activity) and axial (lumbar) and peripheral (midradius) bone mass in a population of 60 young normal, healthy eumenorrheic women (age 25–34 years), selected on the basis of weight for height (within 20% of expected). In this population, vertebral bone mineral density was significantly related (r = 0.41, p < 0.005) to activity pattern but not to calcium intake. Elimination of the effects of activity, however, disclosed a significant correlation between total calcium intake and vertebral bone mass (r = 0.36, p < 0.02). Closer examination of this relationship suggested that vertebral bone mineral density did not appear to increase with calcium intakes above 800–1000 mg/day, implying a threshold effect and vertebral density was better expressed as a function of the logarithm of calcium intake (r = p < 0.01). Radial mineral content was not related to activity (which was mostly walking and running), but it was significantly affected by calcium intake. These data suggest that skeletal status in the vertebrae in young women may be influenced by modulation of mechanical stress. However, bone mineral density is probably also dependent on nutritional status such that the optimum calcium intake for this effect is 800–1000 mg/day. If such effects, observed here cross-sectionally, can be substantiated in longitudinal studies and persist into the aging postmenopausal population, then the average age of onset of osteoporotic fractures would be expected to be delayed approximately 10 years, by relatively simple modifications of diet and activity.
Inhibition of bone collagen synthesis by the tumor promoter phorbol 12-myristate 13-acetate
Authors: Dr. Feyen Jean H.M. , Petersen Donna N. , Kream Barbara E.
Published: February 2010

We characterized the effect of the tumor promoter phorbol 12-myristate 13-acetate (PMA) on osteoblast function and DNA synthesis in 21-day-old fetal rat calvaria maintained in organ culture. Protein synthesis was determined by measuring the incorporation of [3H]proline into collagenase-digestible (CDP) and noncollagen protein (NCP), respectively. Alkaline phosphatase activity was assessed as the release of p-nitrophenol from p-nitrophenol phosphate. DNA synthesis was determined by the incorporation of [3H]thymidine into acid-insoluble bone and total DNA content. PMA at 3–100 ng/ml (4–133 nM) caused a dose-related inhibition of collagen synthesis that was observed 6 hours after adding PMA to calvaria. PMA inhibited collagen synthesis in the osteoblast-rich central bone of calvaria but did not alter collagen synthesis in the periosteum. There was little effect of PMA on noncollagen protein synthesis in the central bone or periosteum. Phorbol esters that do not promote tumor formation in vivo did not alter collagen synthesis in calvaria. PMA stimulated prostaglandin E2 (PGE2) production in calvaria, but indomethacin did not alter the inhibitory effect of PMA on bone collagen synthesis. PMA decreased alkaline phosphatase activity measured after 48 hr of culture and increased the incorporation of [3H]thymidine into bone and DNA content after 96 hr of culture. These data indicate that PMA inhibits collagen synthesis and alkaline phosphatase activity, while stimulating DNA synthesis, suggesting that activation of protein kinase C might regulate osteoblast function and bone cell replication.
Forskolin augments the effects of calcitonin on cytoplasmic spreading of isolated rat osteoclasts and plasma calcium levels in the rat
Authors: Nicholson G.C. , Yumita S. , Moseley J.M. , Yates A.J.P. , Martin T.J.
Published: February 2010

Recently we have shown that forskolin acts synergistically with calcitonin on stimulation of cyclic AMP (cAMP) production in isolated rat osteoclasts and now show that forskolin also augments later physiological responses to calcitonin. The sensitivity of calcitonin inhibition of cytoplasmic spreading in isolated rat osteoclasts was increased 3.5-fold by simultaneous treatment with 10−7M forskolin, which alone had no effect on the response. In weanling rats the threshold of the hypocalcemic response to salmon calcitonin was reduced fivefold by simultaneous treatment with 200 μg/kg forskolin i.v., which alone did not influence the plasma calcium. These results provide further evidence that calcitonin-induced inhibition of osteoclast function is mediated by elevation of cAMP levels and suggest that forskolin could be used to augment the therapeutic effects of calcitonin.
Migration and phenotypic transformation of osteoclast precursors into mature osteoclasts: The effect of a bisphosphonate
Authors: Dr. Löwik Clemens W.G.M. , Van Der Pluijm G. , Van Der Wee-Pals L.J.A. , Van Treslong-De Groot H. Bloys , Bijvoet O.L.M.
Published: February 2010

Osteoclast-devoid bone explants were cultured together with embryonic liver as a source of osteoclast precursors, but separated from each other by a filter. Cells migrated through the filter toward the calcified matrix and acquired the characteristics of mature, tartrate-resistant acid phosphatase-positive (TRAP+) osteoclasts upon contact with the bone explant. Migration and attachment could be visualized separately. Progressive reduction of filter pore size resulted in progressive reduction of resorption because the use of smaller pores made it increasingly difficult for cells to pass. Indeed, the use of 0.22-micron filters, through which no cells can pass, but which still allow full passage of medium, completely blocked the resorption. When migrating cells from fetal liver were arrested for 10 days by using a combination of filters with different pore sizes, the arrested cells showed a tendency to fuse just opposite the mineralized matrix. Furthermore, a great number of the arrested cells expressed the macrophage-specific cell-surface antigen F4/80 and showed acid phosphatase activity, but none of these cells were tartrate resistant. The acquisition of tartrate-resistant acid phosphatase activity upon contact with the bone explant and subsequent resorption of this explant could be prevented by exposure of the system to the bisphosphonate dimethyl-APD (Me2-APD), whereas migration of cells through the filter was not affected. We suggest that the bisphosphonate interferes with a matrix factor that is essential for the attachment and subsequent transformation of the osteoclast precursor into the mature phenotype.
Dose dependency of calcium absorption: A comparison of calcium carbonate and calcium citrate
Authors: Harvey Jean A. , Zobitz Margaret M. , Pak Charles Y.C.
Published: February 2010

Calcium supplementation is recommended as a prophylaxis against bone loss. This study was performed to determine the dose dependency of calcium absorption in an attempt to derive an optimum dose schedule. Using the well-described oral calcium load technique, we measured the calcium absorption from three different calcium doses (0.5, 1.0, and 2.0 g) of both calcium carbonate and calcium citrate administered to 21 normal subjects (4 men and 17 women, 22–60 years). Nine subjects underwent two additional loads with 0.2 g of elemental calcium as calcium carbonate and as calcium citrate. The intestinal calcium absorption from calcium carbonate and calcium citrate was estimated from the rise in urinary calcium following oral ingestion of the respective calcium salt. The increment in urinary calcium post-load, reflective of intestinal calcium absorption, rose rapidly from 0 to 0.5 g calcium loads with only slight subsequent increases from the 0.5 g to 2.0 g calcium doses. Thus, results indicate that 0.5 g of calcium is the optimum dose of either calcium salt. Moreover, the increment in urinary calcium post-load was higher from calcium citrate than from calcium carbonate at all four dosage levels. The increment in urinary calcium (during the second 2 hr) following calcium citrate load (0.5 g calcium) was 0.104 ± 0.096 mg/dl glomerular filtrate (GF), which was higher than that of 0.091 ± 0.068 mg/dl GF obtained from 2.0 g calcium as calcium carbonate. These results confirm the superior calcium bioavailability from calcium citrate as compared with calcium carbonate. To confirm findings from the calcium load technique, 9 subjects underwent calcium absorption test from the fecal recovery of orally administered radiolabeled calcium salts (containing 100–200 mg of elemental calcium). Fractional calcium absorption from calcium citrate of 0.402 ± 0.067 was significantly higher than that of 0.314 ± 0.100 obtained from calcium carbonate. Moreover, calcium loading with either salt did not produce significant citraturic effect during 4 hr of study, ruling out “calcium trapping” by citrate in the renal tubule. In conclusion: (1) Both calcium carbonate and calcium citrate display dose dependency of calcium absorption; (2) calcium is more absorbable from calcium citrate than from calcium carbonate at all four doses employed (0.2, 0.5, 1.0, and 2.0 g); and (3) calcium absorption from 0.5 g of calcium as calcium citrate is greater than that from 2.0 g of calcium as calcium carbonate.
Evidence for a toxic effect of aluminum on osteoblasts: A histomorphometric study in hemodialysis patients with aplastic bone disease
Authors: Parisien M. , Charhon S.A. , Arlot M. , Mainetti E. , Chavassieux P. , Chapuy M.C. , Meunier P.J.
Published: February 2010

To evaluate the potential role of aluminum (Al) in a subset of dialysis patients with aplastic bone disease, we have studied tetracycline-labeled bone biopsies of 32 patients (22 males and 10 females, 45–73 years) on maintenance hemodialysis. Selection criteria included normal resorption surfaces (RS) and osteoid thickness. Eleven patients (Group I) had no stainable bone Al (Al -; 61.7 ± 7.2 years) and 21 (Group II) had stainable bone Al (Al +; 57.7 ± 6.8 years). Serum Al was normal to slightly elevated in Group I, but significantly higher in Group II (p < 0.01). Al surfaces (AlS), undetectable in Group I, were 67.8 ± 17.9% in Group II. Bone Al content (BAC) was much lower in Group I than in Group II (14.8 ± 3.7 vs. 113.8 ± 100.2 μg/g, p < 0.01), but higher in Group I than in controls (p < 0.05). Extensive thin osteoid seams were present in Group II. AlS was correlated with OS (r = 0.56, p < 0.001) and OV (r = 0.48, p < 0.01). Labeled surfaces were decreased in both groups. Labeled osteoid surfaces (TLS/OS) were below 2 SD of the mean control values in 96% of patients and calcification rate (CR) was depressed below 0.20 μm/day in 44% of patients. Bone formation rate (BFR) was strikingly depressed, values being below one SD of the mean control value in 92–100% of patients at both levels and below 2 SD of the mean in 82% of patients at BMU levels. Mineralization lag time (OMP) was markedly prolonged above 2 SD of controls in 89% of patients. A major observation was in the extent of osteoblast osteoid surfaces (OblS/OS) which was found significantly different in Group I (34.2%) than in Group II (15%) (p < 0.001); these differences were consistently found in osteoid surfaces covered by different morphological types of osteoblasts (plump, intermediate, and flat). Negative correlations were found between AlS and OblS/OS (r = −0.57, p < 0.001), intermediate OblS/OS (r = −0.38, p < 0.05) and flat OblS/OS (r = −0.56, p < 0.01). These findings indicate an impairment of osteoblastic function, with depression of bone formation at all levels, and strongly suggest a toxic effect of Al on osteoblasts.
Effects of transforming growth factor type beta upon bone cell populations grown either in monolayer or semisolid medium
Authors: Dr. Guenther Harald L. , Cecchini Marco G. , Elford Peter R. , Fleisch Herbert
Published: February 2010

Bone has been shown to store large amounts of transforming growth factor type beta (TGFβ) and this has recently been found to be synthesized by bone-forming cells. We report on studies undertaken to examine the effects of platelet-derived TGFβ on different bone cell populations, isolated from 1-day postnatal rat calvaria by sequential enzymatic digestion. In addition, we tried to determine which of these cell populations synthesize TGFβ. In this regard, evidence was collected to indicate that cell populations which were shown to be enriched with osteoblast-like cells synthesize TGFβ. Although the production of the factor appeared to be limited to a particular cell type, its action was found to be of a more general character, as all cell populations were found to respond to TGFβ. Contrary to earlier reports, TGFβ was shown to be inhibitory upon cell proliferation. In this context, growth of cells released during early digestions was reduced considerably more than growth of those released during late digestions. Studies on the effect upon protein synthesis revealed that TGFβ specifically inhibited collagen but not the synthesis of noncollagenous proteins. The synthesis of collagen was altered to a greater extent in cells isolated during late digestions than in cells of the early populations. Further information on the TGFβ-mediated effects on bone cell biology was provided by data showing that both alkaline phosphatase and cAMP production in response to PTH was greatly reduced by TGFβ. Finally, experiments performed to determine whether TGFβ induces any of the bone cell populations to acquire the transformed phenotype revealed that only populations previously shown to be enriched with osteoblast-like cells formed colonies in soft agarose. In summary, differential action of TGFβ on various bone cell populations observed in these studies and its abundance in bone suggests that this polypeptide factor may constitute an important element in events that balance the function of bone cells according to the physiological requirements of bone.
Glucose transport in osteoblast-enriched bone explants: Characterization and insulin regulation
Authors: Dr. Hahn Theodore J. , Westbrook Scott L. , Sullivan Theresa L. , Goodman William G. , Halstead Linda R.
Published: February 2010

Insulin has potent effects on osteoblast function both in vivo and in vitro. In various insulin-sensitive tissues, stimulation of glucose transport and metabolism are hallmarks of insulin action, and have been postulated to play a role in insulin regulation of cellular function. However, insulin effects on glucose metabolism in osteoblast-like cells have not been demonstrated. Therefore we examined the in vitro effects of insulin on hexose uptake in an osteoblast-enriched rat bone explant preparation. Uniform 5-mm-diameter punch sections were obtained from the cartilage-free frontal portions of the calvaria of 3-day-old rats, and the periosteum was removed. The resulting sections contained a highly enriched population of osteoblast-like cells as determined by histologic criteria, elimination of calcitonin-stimulatable cAMP generation, and enhancement of PTH-stimulatable cAMP generation per microgram of DNA. Sections were incubated for 24 hr at 37°C in BGJb medium and then transferred to modified glucose-free Krebs-Ringer bicarbonate buffer for 2-deoxy-D-glucose (2-DG) uptake studies. 3H-2-DG uptake was linear with time over 60 min, temperature sensitive, and inhibited by 5 mA/phloridzin. Kinetic analysis of 2-DG uptake at 25°C demonstrated a saturable transport mechanism with a Km of 2.2 mM, similar to that observed for 2-DG transport in other tissues. Studies of competitive inhibition by other sugars demonstrated a transport specificity for 2-DG that was comparable to that previously observed in fat and muscle cells. 2-DG uptake was rapidly stimulated by insulin (0.5 nM-1 μM), with maximal insulin effect observed at 50 nM. Concanavalin A (10–50 μg/ml) produced a similar stimulation of 2-DG transport. Both basal and insulin-stimulated uptake were inhibited reversibly by cytochalasin B (50 μM). Insulin stimulation of 2-DG uptake was the result of increased transport Vmax, with Km remaining constant. These studies provide the first demonstration that the cell population of osteoblast-enriched bone explants possesses an insulin-stimulatable glucose transport system with characteristics similar to those found in other insuln-sensitive tissues.
Transfusion of carbonic anhydrase-replete erythrocytes fails to correct the acidification defect in the syndrome of osteopetrosis, renal tubular acidosis, and cerebral calcification (Carbonic Anhydrase-II Deficiency)
Authors: Dr. Whyte Michael P. , Lee Hamm Lotuce , Sly William S.
Published: February 2010

We explored the effects of transfusion of carbonic anhydrase II (CA-II)-replete erythrocytes on systemic pH, serum electrolytes, and urinary acidification of a patient with CA-II deficiency. Pretransfusion studies documented hyperchloremic acidosis, increased urinary pH with decreased titratable acidity, and profound CA-II deficiency in erythrocytes. During transfusion, CA-II in circulating erythrocytes increased to above the half-normal levels seen in asymptomatic heterozygote carriers of CA-II deficiency. However, no significant change occurred in venous, arterial or urinary pH, serum electrolytes, and urinary acid excretion during the transfusion or during the subsequent 60 hr of observation. These studies argue that the renal acidification defect in CA-II deficiency results from deficiency of CA-II in the renal parenchyma, and is not secondary to deficiency of CA-II in erythrocytes. Bone marrow transplantation is not a promising approach to correct the renal manifestations of CA-II deficiency.
Further biochemical and molecular characterization of primary rat parietal bone cell cultures
Authors: Dr. McCarthy Thomas L. , Centrella Michael , Canalis Ernesto
Published: February 2010

Primary bone cell cultures are used widely to examine the regulation of bone metabolism by growth factors and hormones. Characterization of this model system is now being conducted at the molecular level to define modulation of gene expression. Cells were obtained from rat parietal bone by sequential collagenase digestions. Cell populations were evaluated for bone-related products, including collagen isoform expression and mRNA levels, alkaline phosphatase activity, and osteocalcin production. Serum-deprived, confluent cultures of the first and second collagenase-released populations produced a lower percentage of total protein as collagen than the third, fourth, and fifth populations, while co-culturing the third through fifth populations resulted in the highest level. Collagen typing on SDS-polyacrylamide gels revealed an abundance of mature type I collagen in all cell populations; type III collagen synthesis was undetectable by this method. This is in contrast to the presence of cytoplasmic mRNA for both type I and type III collagen in all cell populations, suggesting post-transcriptional modulation of type III collagen synthesis. The expression of alkaline phosphatase and osteocalcin was highest in cultures of later released cells, indicating that these cell populations display phenotypic characteristics associated with cells of the osteoblast lineage.
The effects of phenytoin on calcium uptake in osteoblastic cells
Authors: Dr. Dziak R. , Vernillo A. , Rifkin B.
Published: February 2010

The effects of Phenytoin (diphenylhydantoin, DPH) on calcium uptake in osteoblastic cells were studied to elucidate the potential mechanism of action of this antiepileptic drug on bone metabolism. Preincubation of the human osteoblastic osteosarcoma) cell line, SaOS-2, and normal rat osteoblastic cells with DPH decreased basal calcium uptake. This inhibition occurred at DPH doses from 0.1 to 50 μg/ml. Parathyroid hormone (PTH) and prostaglandin E2 (PGE2) increased calcium uptake in the SaOS-2 cell line. Following preincubation with DPH, calcium uptake in cells treated with PTH or PGE2 did not exceed control levels. However, significant increases in the PTH- or PGE2-treated + DPH-pretreated cells compared to DPH pretreatment alone were still observed. These studies indicate that DPH induces decreases in osteoblastic calcium influx and they add further information on the possible mode of action of this drug on bone.
The effects of forskolin and calcium ionophore A23187 on secretion and cytoplasmic RNA levels of Chromogranin-A and calcitonin
Authors: Murray Samuel S. , Burton Douglas W. , Dr. Deftos Leonard J.
Published: February 2010

We have studied the regulation of the secretion and cytoplasmic RNA levels of calcitonin (CT) and Chromogranin-A (CgA) to determine if the biosynthesis and secretion of these two substances are controlled in a coordinated fashion. The studies were conducted in two cell lines, a medullary thryoid carcinoma (MTC) cell line and a lung tumor (BEN) cell line. Both cell types secrete CT and CgA. Forskolin treatment resulted in a significant increase in the secretion of CT and CgA in each cell line and in CT-specific cytoplasmic RNA in the MTC cell line. Treatment with calcium ionophore A23187 resulted in significantly increased secretion of both substances in the lung tumor cells but not in the medullary thyroid carcinoma cells. A significant increase in CT-specific or CgA-specific cytoplasmic RNA was not seen in either cell line. We conclude that the secretion of CT and CgA are regulated in a coordinated fashion in these cell lines through processes that are calcium-mediated and processes that involve cyclic AMP-dependent protein kinase A. However, each of these regulatory pathways is not always operative in a given tissue. The coordinate regulation of the secretion of CT and CgA supports the hypothesis that CgA participates in the secretory process of its associated hormones.
Parathyroid hormone receptors in human dermal fibroblasts: Structural and functional characterization
Authors: Pun K.K. , Arnaud Claude D. , Dr. Nissenson Robert A.
Published: February 2010

Previous studies have established the presence of parathyroid hormone (PTH)-sensitive adenylate cyclase activity in cultured human skin fibroblasts. The present study was undertaken to identify and quantitate PTH receptors directly in such cells. Human dermal fibroblast cell line CRL 1564 was found to possess specific binding sites for [125I]PTH(1–34). These sites bound PTH selectively; bovine and human PTH(1–34) and PTH(1–84) competed for [125I]PTH(1-34) binding sites, whereas the unrelated peptides calcitonin, insulin, AVP, angiotensin II, and ACTH(1–24) were inactive even at micromolar concentrations. Competitive binding experiments demonstrated the presence of binding site heterogeneity. These data fit a “two-site” model (p < 0.001) in which one binding component has high affinity (Kd = 2.5 ng/ml = 0.6 nM) and low capacity (104 sites/cell) while the other has low affinity (Kd = 5.9 μg/ml = 1.5 μM) and high capacity (>107 sites/cell). Similar high- and low-affinity [125I]bPTH(1–34) binding sites were seen also in CRL 1564 membranes containing a PTH-responsive adenylate cyclase. The Kd of the high-affinity sites was identical to the concentration of unlabeled bPTH(1–34) (4.2 ng/ml = 1.0 nM) required to half-maximally elevated cyclic AMP in CRL 1564 cells. Affinity labeling of specific PTH binding sites revealed the presence of multiple components with Mrs of 85, 70, 40, 33, and 23 kD on SDS-PAGE. Competition experiments did not disclose structurally discrete high- and low-affinity sites. Thus, structurally homologous PTH receptors in human skin fibroblasts apparently can assume two affinity states: (i) a high-affinity state coupled to adenylate cyclase and (ii) a low-affinity state that may represent uncoupled receptors.
Malignant osteoporosis and defective immunoregulation
Authors: Rubin Karen R. , Ballow Mark , Baron Roland , Greenstein Robert M. , Raisz Lawrence G. , Rowe David W.
Published: February 2010

The linkage between immune cells and the osteoclast has become partially understood in the laboratory, but the full spectrum of clinical disorders of this relationship remain to be elucidated. We report a 29-month-old girl with recurrent infections and multiple fractures. Immune evaluation showed normal quantitative serum immunoglobulins but absent antibodies to the respiratory viruses and tetanus toxoid and decreased in vitro polyclonal-induced immunoglobulin production. Further analysis in vitro with separated lymphocyte populations showed normal B cell function but markedly increased suppressor T cell activity. The bone evaluation showed diffuse osteopenia on x-ray. Serum calcium, phosphorus, PTH, 25-hydroxyvitamin D, and 1,25-dihydroxyvitamin D were normal for age. Urinary calcium excretion (24 h) was, however, two times normal. An iliac crest biopsy confirmed the presence of extreme osteopenia with normal mineralization and numerous small atypical osteoclasts resorbing the bone. No circulating plasma resorptive activity was demonstrated. Calcitonin therapy markedly diminished the patient's hypercalciuria. We speculate that this patient's increased bone resorption, decreased bone formation, and suppressor activity may be linked by a common pathway involving the abnormal function of immune cells. Since no similar constellation of findings has been previously reported, this case may represent a new congenital disorder: severe osteopenia associated with increased osteoclast activity in association with a defect in T cell immunoregulation.
Differences in the kinetics of the mineralization process in endochondral and intramembranous osteogenesis in human fetal development
Authors: Dr. Dziedzic-Goclawska A. , Emerich J. , Grzesik W. , Stachowicz W. , Michalik J. , Ostrowski K.
Published: February 2010

About 300 samples of bone tissue from femoral diaphyses and from parietal bones of calvaria were collected from human fetuses aged from 6–8 to 40–41 weeks in order to compare the kinetics of the mineralization process in endochondral and intramembranous bone formation. The crystallinity of bone mineral was evaluated by the method based on electron spin resonance (ESR) spectrometry, and mineral content was measured after ashing of the samples.

Highly significant differences in the kinetics of deposition of mineral (ash content) and maturation of deposited mineral (crystallinity coefficient) were found between parietal bones and femoral diaphyses in the course of fetal development. In the early stages of development (6–8 to 10–12 weeks), the content of mineral and its crystallinity in parietal bones were significantly lower than in femoral diaphyses. In the parietal bones a gradual increase in both values was observed until they reached a plateau at the age of 30 weeks. On the other hand, in femoral diaphyses of 6–8-week-old fetuses mineral content was high and deposited mineral showed a high degree of crystallinity. Both these values did not change significantly until birth. The differences in kinetics of the mineralization process between the weight-bearing bones and bones that are not exposed to the influence of strong external forces are most probably genetically conditioned. The collected data supply embryological information and might be used in the future for evaluation of pathologic changes in skeletal development.
Early vertebral trabecular bone loss in normal premenopausal women
Authors: Buchanan James R. , Myers Cathleen , Lloyd Tom , Greer Robert B.
Published: February 2010

The precise timing for the onset of trabecular bone loss in women is a matter of controversy. To address this issue, we studied the relationship between age and vertebral trabecular bone density (measured by computed tomography) in 74 healthy premenopausal women from 18 to 48 years old. We also measured radial cortical bone density (by single photon absorptiometry) in 28 of these subjects.

Trabecular bone density levels (milligrams per milliliter, mean ± standard error of the mean, SEM) were significantly (p < 0.05) higher in the second (178 ± 8) and third (171 ± 6) decades than in the fourth (158 ± 4) or fifth (140 ± 12) decades, and were inversely correlated with age (r = -0.39, p = 0.0006), diminishing at a rate of 1.3 mg/ml (0.73%) per year. Radial cortical bone density levels (grams per square centimeter) were similar in the third (0.711 ± 0.021), fourth (0.721 ± 0.012), and fifth (0.736 ± 0.012) decades and were not related to age (r = 0.17, p = 0.39).

We conclude that vertebral trabecular bone loss in women commences during or prior to the third decade. In contrast, radial cortical bone density does not decline during the premenopausal years.
Bone mineral density in australia compared with the united states
Authors: Pocock Nicholas A. , Dr. Eisman John A. , Mazess Richard B. , Sambrook Philip N. , Yeates Michael G. , Freund Judith
Published: February 2010

Bone density measurements are currently being performed throughout the world in the diagnosis and management of osteoporosis as well as in research into this major health problem. However, it is not clear to what extent bone mineral density (BMD) values determined by dual-photon absorptiometry at one center can be applied to another. This is particularly relevant for the quantitative comparison of results from studies carried out in different laboratories. Furthermore, many centers now acquiring densitometers may not have the resources to determine their own normal range, relying instead on a “normal” range provided by the manufacturer. The question of the comparability of BMD data obtained in different centers was examined by comparing the normal range for the lumbar spine and proximal femur in 203 normal white Australian women and 892 normal white U.S. women, obtained using the same model densitometer.

The two populations were compared according to decade. From superimposition of the Australian individual values on the North American normal ranges, only minor differences between the two populations were seen at any of the sites measured at any decade. None of these minor differences were statistically significant.

This study shows a close similarity between BMD values in both the proximal femur and lumbar spine in normal white women in Australia and North America, provided the same model densitometer is used. Thus data obtained from different centers in populations with similar ethnic composition may be compared directly. These findings provide for the first time a sound basis for the quantitative comparison of the at times conflicting studies carried out in widely differing settings around the world.
Bone-resorbing agents promote and interferon-γ inhibits bone cell collagenase production
Authors: Shen Victor , Kohler Gail , Jeffrey John J. , Peck William A.
Published: February 2010

Parathyroid hormone, prostaglandin E2, 1α,25-dihydroxyvitamin D3, interleukin-1, tumor necrosis factor α, and epidermal growth factor, all known stimulators of bone resorption, markedly enhanced collagenase secretion by rat fetus osteoblastlike cells in primary culture as judged by enzyme-linked immunosorbent assay. Untreated cells contained no immunostainable or extractable collagenase. Collagenase was detected in the treated cells and media only after 1–3 h of treatment, and there was no increment in collagenase activity when cells were treated in the presence of actinomycin D or cycloheximide. Cells secreted collagenase in a latent form and also elaborated collagenase inhibitor; chromatographic separation of collagenase from collagenase inhibitor and subsequent activation of the collagenase with trypsin yielded the active species in stimulated but not in unstimulated cells. The ability of individual prostanoids, among seven tested, to promote collagenase production correlated positively with their reported capacity to promote bone resorption. Interferon-γ (IFN-γ), a known resorption inhibitor, blocked the increment in collagenase production caused by all agents tested. These results indicate a close linkage between stimulation of bone resorption and collagenase production by osteoblastlike cells. Various resorption stimulators, including some not previously tested for effects on collagenase, augment the de novo synthesis and secretion of collagenase and act by an IFN-γ-inhibitable mechanism.
Characteristics of an ovariectomized osteopenic rat model
Authors: Yamazaki Iwao , Yamaguchi Hikoharu
Published: February 2010

Although osteoporosis induced by ovariectomy (Ovx) in the rat has been widely used as a model for postmenopausal osteoporosis in humans, the findings of different investigators are not always consistent. This might be mainly due to differences in the age of the animals at Ovx, time after Ovx, and the variables measured. Therefore, in the present study, Ovx was performed at 4, 10, or 52 weeks and bone changes were observed in rats for 6 months. The effects of Ovx on body weight, femoral length, and femoral volume were marked in rats operated on at the age of 4 weeks, slight in rats operated on at the age of 52 weeks, and intermediate in rats operated on at the age of 10 weeks. A reduction in the ratio of cortical thickness to bone width at the midshaft of the femur was observed only in rats ovariectomized at 52 weeks of age. The specific gravity of the femur and the density of the metaphysis of the femur decreased after Ovx in all rats. The ratio of ash weight to dry weight of the femur, a measure of the normal calcification of bone, was unchanged shortly after Ovx but gradually decreased in all rats.
Purification and characterization of human bone tartrate-resistant acid phosphatase
Authors: Allen Susan H. , Nuttleman Peter R. , Ketcham Catherine M. , Roberts R. Michael
Published: February 2010

Tartrate-resistant acid phosphatase (TRAP) is a histochemical marker for osteoclasts, the multinucleated bone resorbing cell. This type 5 acid phosphatase has been purified 500-fold from human bone by three chromatographic steps: cation exchange, gel filtration, and HPLC cation exchange. Like most other TRAPs isolated, it is a basic glycoprotein of a molecular weight about 33,000. Its pH optimum, Km, and Vmax for p-nitrophenyl phosphate are 5.7, 0.8 mM, and 12 units/mg, respectively. Human bone TRAP hydrolyzes aryl phosphates, nucleoside di- and triphosphates, pyrophosphate, and phosphoproteins. It is activated by mild reducing agents but inhibited by molybdate, fluoride, arsenate, phosphate, and dithionite. Its activity is not inhibited by tartrate, a feature that distinguishes it from other acid phosphatases. Sodium etridonate, the bisphosphonate used clinically to reduce bone resorption, is a relatively poor inhibitor of bone TRAP. Human bone TRAP is immunologically related to the porcine uterine secretory TRAP, uteroferrin. Monospecific rabbit antibodies to the bone TRAP have been immunopurified by using affinity chromatography with uteroferrin immobilized on Sepharose and can be used to detect low amounts of the enzyme in a simple dot-blot assay.
Parathyroid function in paget's disease of bone
Authors: Siris Ethel S. , Clemens Thomas P. , McMahon Don , Gordon Arline , Jacobs Thomas P. , Canfield Robert E.
Published: February 2010

In order to determine the prevalence of secondary hyperparathyroidism in patients with Paget's disease of bone, we measured serum parathyroid hormone levels (N-terminal assay) in 39 patients with a wide range of pagetic activity. All patients had normal serum calcium levels. A total of 30 patients were either untreated or had received no treatment for 6 months or longer when studied; the other 9 were receiving either salmon calcitonin (3) or EHDP (6). The results showed that in 7 of the 39 patients (18%) parathyroid hormone levels were increased above normal. These were among the most severely affected cases, as manifested by the degree of elevation of three pagetic biochemical indices: serum alkaline phosphatase, plasma bone Gla protein, and 24 h urinary hydroxyproline-creatinine ratios. Levels of 25-hydroxyvitamin D3 and 1,25-dihydroxyvitamin D3 were normal.

We examined the relationships between parathyroid hormone and each of the three pagetic indices as well as serum calcium for the entire group of 39 patients. Parathyroid hormone values did not correlate with serum calcium measurements (r = −0.241, p = NS) but did correlate significantly with serum alkaline phosphatase (r = 0.496, p < 0.001), plasma bone Gla protein (r = 0.537, p < 0.001), and urinary hydroxy-proline (r = 0.450, p < 0.011). We conclude that relative or absolute increases in parathyroid hormone may occur in moderately active Paget's disease, possibly in the setting of greater calcium demands during periods of increased pagetic new bone formation. This may be of pathophysiologic importance, since higher concentrations of parathyroid hormone may drive responsive pagetic osteoclasts to levels of bone-resorbing activity that exceed their intrinsically augmented states, contributing to the metabolic expression of the Paget's disease.
Effects of oral contraceptive and estrogen administration on plasma calcitonin in pre- and postmenopausal women
Authors: Hurley Daniel L. , Tiegs Robert D. , Barta Joyce , Laakso Karen , Dr. Heath Hunter
Published: February 2010

Estrogen (E) therapy and administration of oral contraceptives (OC) reportedly increase plasma calcitonin (CT) concentrations in women, effects said to mediate in part the beneficial actions of E on bone. To further examine this theory, we tested the effects of three cycles of OC therapy in 12 young women, comparing them to 10 healthy women before and after three normal menstrual cycles. We also determined the effects of 3 months of E therapy (ethinyl estradiol, 20 μg/day, 25 of 30 days) in 14 healthy postmenopausal women, using a crossover design (studied after 3 months with and 3 months without E). We determined CT by radioimmunoassay (antiserum G-1701) in whole plasma (iCT) and silica cartridge extracts of plasma (exCT) after overnight fasting, after calcium (Ca) infusion (2 mg Ca/kg over 5 minutes), and during a normal day at 0800, 1200, 1700, and 2000 h. In no control study was there a significant diurnal change in iCT or exCT, and neither OC nor E therapy altered this. Similarly, OC administration did not affect basal CT levels or the normal iCT and exCT responses to Ca infusion. E therapy induced expected changes in serum Ca, phosphorus, and alkaline phosphatase and urinary Ca and cAMP excretion; basal and diurnal plasma exCT levels were decreased significantly, consonant with the decrement in serum Ca. E did not alter normal iCT and exCT responses to Ca infusion. Thus, administration of either OC or E has no stimulatory effect on CT secretion, which suggests that the beneficial actions of E on bone are not mediated through CT-induced inhibition of bone resorption. Interaction of E with CT action at the cellular level is not excluded by these findings, but there are no data to support such a proposal.
Bone mineral density in women with type II diabetes mellitus
Authors: Weinstock Ruth S. , Goland Robin S. , Shane Elizabeth , Clemens Thomas L. , Lindsay Robert , Dr. Bilezikian John P.
Published: February 2010

Bone mineral density (BMD) was assessed in 28 women with type II diabetes mellitus and compared to 207 age-matched nondiabetic women. Mean BMD, as measured by dual-photon absorptiometry, 1.12 ± 0.3 g/cm2 (±SEM), was similar to the mean BMD of control subjects, 1.06 ± 0.1 g/cm2. Only 1 of the 28 diabetic patients had a BMD less than 0.95 g/cm2 (“fracture threshold”), whereas 25% of the control subjects had a BMD below that level. When diabetic and control subjects were matched for weight as well as age, the data continued to show similar BMD among both groups. Moreover, the disparity between the proportion of weight-matched controls (25%) and diabetic subjects (1 of 28) with a BMD below the fracture threshold persisted. Among the group of 17 diabetic subjects receiving insulin, there was a positive relationship between BMD and insulin dose. There was no significant relationship between BMD, duration of diabetes, or hemoglobin A1c. Thus, women with type II diabetes are not at increased risk for diminished BMD and may be protected against bone loss.
A model system for assessing physicochemical factors affecting calcium absorbability from the intestinal tract
Authors: Dr. Pak Charles Y.C. , Poindexter John , Finlayson Birdwell
Published: February 2010

An in vitro model system was utilized to critically examine physicochemical factors that could play a role in determining the amount of potentially absorbable ionic calcium as well as soluble complexes in the proximal jejunum following ingestion of tricalcium dicitrate, calcium carbonate, or tricalcium diphosphate. The solubility of calcium salts (500 mg calcium each) was tested in 300 ml water containing varying amounts of hydrochloric acid (0, 0.72, 2.4, 7.26, and 24.2 mEq) intended to mimic achlorhydric to peak acid secretory states. Whereas 20% of calcium citrate dissolved in the absence of hydrochloric acid, a negligible amount of calcium carbonate and calcium phosphate underwent dissolution. In solutions containing 0.72–7.26 mEq hydrochloric acid, calcium citrate was more than twofold soluble than calcium carbonate, and calcium phosphate had intermediate solubility. At simulated peak acid secretion, all three salts were completely soluble, or nearly so.

To simulate pancreatic bicarbonate secretion, the filtrates obtained from solubility studies were titrated to pH 5, 6, and 7 with sodium hydroxide. Reprecipitation of calcium citrate and calcium carbonate did not occur. However, substantial calcium phosphate reprecipitation took place especially at high pH and in filtrates derived from high hydrochloric acid content.

In filtrates derived from reprecipitation experiments (at pH 6 and 7), anionic complexation of calcium was calculated in order to estimate the amount of ionic and complexed calcium. Considerable amount of calcium from dissolved calcium citrate was complexed (60–65%), principally as soluble CaCit−, whereas calcium complexation was negligible in the calcium carbonate and calcium phosphate systems.
Regulation of osteosarcoma EGF receptor affinity by phorbol ester and cyclic AMP
Authors: Borst Stephen E. , Catherwood Bayard D.
Published: February 2010

We studied the binding and degradation of 125I-labeled epidermal growth factor (EGF) by UMR-106 osteosarcoma cells and the regulation of EGF receptor affinity for EGF by the phorbol ester 12-O-tetradecanoyl-phorbol-13-acetate (TPA) and by treatments that raise intracellular levels of cyclic AMP. Cell surface binding of [125I]EGF to A431 cells reached a plateau after a 30 minute incubation at 37°C but was undetectable in UMR-106 cells. Degradation of [125I]EGF proceeded at a 50-fold higher rate in A431 cells on a per cell basis, but receptor-bound [125I]EGF was internalized and degraded at a 3.5-fold higher rate by UMR-106 cells on a per receptor basis. At 4°C, [125I]EGF labeled a single class of surface binding sites in the UMR-106 cell. Treatment with TPA at 37°C reduced subsequent cell surface binding of [125I]EGF at 4°C a maximum of 80% with an IC50 of 1.25 ng/ml. Maximal TPA reduction of [125I]EGF binding was observed within 5–15 minutes and was due to a reduction in the affinity of cell surface receptors of [125I]EGF without a change in receptor density. Pretreatment of the cells for 4 h with 30 μM forskolin, 1 mM isobutylmethylxanthine (IBMX) plus 30 μM forskolin, or 1 mM IBMX plus 100 ng/ml parathyroid hormone (PTH) attenuated the loss in [125I]EGF binding caused by a subsequent dose of 10 ng/ml of TPA by 17% (p < 0.0005), 39% (p < 0.0002), and 35% (p < 0.002), respectively. We concluded that activation of protein kinase C decreases the affinity of UMR-106 EGF receptors and that this action may be opposed by the activation of cyclic AMP-dependent protein kinase.