bluuebunny/crossref_metadata_2025 huggingface dataset:
Role of ascorbic acid in the regulation of proliferation in osteoblast-like MC3T3-El cells
Authors: Harada Shun-Ichi , Matsumoto Toshio , Ogata Etsuro
Published: February 2010

Proliferation of osteoblast-like MC3T3-El cells was minimal in serum-free Eagle's minimum essential medium (MEM) but was enhanced by about 3.5-fold in serum-free (alpha)-modification of MEM ((alpha)-MEM). By adding back each of the extra constituents present in (alpha)-MEM to MEM, it was found that ascorbic acid was responsible for the sustained proliferation of MC3T3-El cells without serum. Ascorbic acid also stimulated the synthesis of collagen and increased the hydroxyproline content of MC3T3-El cell cultures markedly. Inhibitors of collagen synthesis, L-azetidine-2-carboxylic acid, cis-4-hydroxyproline, and 3,4-dehydroproline, almost completely eliminated the stimulatory effect of ascorbic acid on DNA synthesis of MC3T3-El cells. The dose response of the effect of L-azetidine-2-carboxylic acid on the hydroxyproline content closely paralleled that on DNA synthesis of MC3T3-El cells. Furthermore, a 10 times higher concentration of proline, which competes with L-azetidine-2-carboxylic acid for the incorporation into procollagen molecules, reversed the inhibition of DNA synthesis by L-azetidine-2-carboxylic acid. These results are consistent with the assumption that the stimulatory effect of ascorbic acid on the proliferation of MC3T3-El cells is mediated through its effect on the synthesis of collagen or some related protein. Furthermore, a fibronectin attachment peptide, GRGDTP, that competes with matrix proteins for specific binding to cell surface adhesion receptors also inhibited the stimulation of proliferation by ascorbic acid almost completely. It is suggested that ascorbic acid stimulates osteoblast proliferation through its effect on the synthesis of collagen or some related protein and that such a matrix protein interacts with cell surface adhesion receptors to cause the stimulation of proliferation in osteoblasts. The mechanism of how such a protein affects the proliferation of osteoblasts remains to be clarified.
Characterization of bone cells isolated on discontinuous percoll gradients: Distribution in sequentially derived populations
Authors: Wong Glenda L. , Ng May C. , Calabrese David W. , Swartzendruber Douglas E.
Published: February 2010

Bone cell populations obtained by sequential digestion of newborn mouse calvariae remain morphologically heterogeneous despite well-documented biochemical differences. Fractionation of these populations on Percoll gradient reveal three major cell groups of low, intermediate, and high buoyant density (1.056, 1.070, and 1.095 g/ml) that are present in different ratios in early and late released populations. Cells of low and intermediate density dominate in early released populations. In contrast, late released populations contain mostly high-density cells. Basal levels of alkaline phosphatase are highest in cells of intermediate buoyant density. All cells respond to PTH with cAMP production and morphologic transformation, but biochemical responses to PTH, such as secretion of insulin-like growth factor I (IGF-I) and stimulation of alkaline phosphatase activity, occur mostly in cells of intermediate density. These data suggest that (1) subclasses of osteoblasts can be further separated by density and (2) PTH effects on alkaline phosphatase activity and IGF-I secretion are probably expressed by osteoblasts of a certain subclass and/or stage of development.
Precision and sensitivity of dual-energy X-ray absorptiometry in spinal osteoporosis
Authors: Pouilles Jean-Michel , Tremollieres Florence , Todorovsky Natacha , Pr. Ribot Claude
Published: February 2010

This study evaluated the performance of dual-energy x-ray absorptiometry (DEXA) with regard to (1) the correlation with dual-photon absorptiometry (DPA), (2) the ability to discriminate between normal and osteoporotic patients, and (3) long-term reproducibility. The bone mineral density (BMD) of the spine in 112 subjects, both normal and osteoporotic, was measured with DPA and DEXA (Lunar Corporation, Madison, Wisconsin) of the spine. The femur BMD of 22 cases was also measured with both machines. The results for the two techniques were highly correlated (r > 0.9, SEM = 0.02 to 0.04 g/cm2). BMD was measured using DEXA in 80 women (mean age = 61 years) with established spinal osteoporosis and 110 normal age-matched controls. The osteoporotic patients had significantly reduced spine and femur BMDs compared to the controls: −23% for L2–4 BMD (Z score = 2.6) and −13 to −20% for femur BMD (Z score = 1.1–1.3). L2–4 BMD had the best discriminative value, with an area under the ROC curve of 94%; the Ward's triangle BMD had an area of 84%. The precision error in vitro in a phantom over a 1-year period was 0.7%. The measured precision in vivo with young adults was approximately 1% (SD = 0.012 g/cm2) for L2–4 BMD and 1.7–2.3% (SD = 0.015–0.022 g/cm2) for femur over the 1 year period. The reproducibility was not as good for osteoporotic patients (SD = 0.017 g/cm2).
cDNA and deduced amino acid sequence of mouse matrix gla protein: One of five glutamic acid residues potentially modified to gla is not conserved in the mouse sequence
Authors: Dr. Ikeda Tohru , Yamaguchi Akira , Icho Tateo , Tsuchida Nobuo , Yoshiki Shusaku
Published: February 2010

A cDNA library was constructed using the mouse osteoblastic cell line MC3T3-E1 treated with 1α,25-dihydroxyvitamin D3, based on the finding that the treatment increased ninefold the expression of 0.7 kb matrix gla protein (MGP) mRNA. cDNA clones encoding mouse MGP were isolated from the library. The nucleotide sequence showed an open reading frame of 312 nucleotides encoding 104 amino acids. Murine MGP shared 84–89% amino acid sequence homology with bovine, rat, and human MGP. However, there are five glutamic acid residues potentially modified to γ-carboxyglutamic acid (gla) in those species; in murine MGP, lysine replaced glutamic acid 37. Also, an extra tyrosine was added at the carboxyl terminus. The significance of the substitution is discussed in relation to the γ-carboxylation sites in MGP protein.
Vitamin D analogs with low affinity for the vitamin D binding protein: Enhanced in vitro and decreased in vivo activity
Authors: Dr. Bouillon Roger , Allewaert Katrien , Xiang Da Zhen , Tan Biauw Keng , van Baelen Hugo
Published: February 2010

The affinity of 1α,25-dihydroxyvitamin D3 [1α,25-(OH)2D3] and analogs with side-chain modifications [MC 903 or calcipotriol, MC 1147 or 24,24-dihomo-1α,25-(OH)2D3 and 1,25-(OH)2-16ene-23yne-D3] for the vitamin D receptor and the serum vitamin D binding protein (DBP) were compared. The affinity of MC 903 for the receptor from chick and rat duodenum or from human peripheral blood mononuclear cells or HL-60 cells varied between 60 and 100% relative to the affinity of 1,25-(OH)2D3. The relative affinity of 1,25-(OH)2-16ene-23yne-D3 and MC 1147 varied for the same receptors between 45–70 and 3.5–25%, respectively. The relative affinity of MC 903 for human DBP was 30-fold decreased, whereas the two other analogs did not bind to DBP at all even in more than 1000-fold excess. The in vitro biologic activity of 1α,25-(OH)2D3 on phytohemagglutinin-stimulated normal human lymphocyte proliferation was markedly inhibited by the addition of physiologic amounts of DBP to the cell culture medium. No such inhibition was observed when MC 903 or 1147 was evaluated similarly. DBP therefore reversed the rank order of the in vitro potency of these analogs. Intramuscular injections for 10 consecutive days to vitamin D-deficient chicks demonstrated a ≥ 100-fold lower biologic activity of MC 903, MC 1147, and 1,25-(OH)2-16ene-23yne-D3 compared to that of 1α,25-(OH)2D3 as evaluated by serum calcium and osteocalcin concentrations, as well as by duodenal calbindin D28K and bone calcium content. We conclude that the biologic activity of vitamin D metabolites and analogs depends on their affinity for the vitamin D receptor as well as their affinity for DBP. Analogs with a low DBP but good receptor binding properties display low in vivo biologic activity on calcium and bone homeostasis, at least partly due to altered pharmacokinetics.
Tissue and urokinase plasminogen activators in bone tissue and their regulation by parathyroid hormone
Authors: Leloup Gaetane , Peeters-Joris Chantal , Delaisse Jean-Marie , Opdenakker Ghislain , Vaes Gilbert
Published: February 2010

The identification of the plasminogen activator (PA) types present in bone and the regulation of their activity by parathyroid hormone (PTH) were investigated in cultures of fetal mouse calvariae with the use of either a chromogenic substrate or a zymographic assay. PA was detected essentially in the tissue extracts of the explanted bones, with only 1–2% of the total activity released in the surrounding culture media. From their electrophoretic behavior compared to PAs of other mouse tissues and from their response to a specific antibody raised against the tissue type PA (tPA), two major molecular species, of 70 and 48 kD were identified as tPA and urokinase (uPA), respectively, a third minor species of 105 kD being likely to correspond to complexes between tPA and an inhibitor; the culture fluids, moreover, contained enzymatically active degradation products of uPA of 42 and 29 kD. The PA activity of the bone extracts was only minimally affected by the addition of fibrinogen fragments to the chromogenic assays. PTH induced bone resorption and stimulated in parallel the accumulation of PA in the tissue; other bone-resorbing agents, 1,25-dihydroxyvitamin D, and prostaglandin E2, had similar effects. Densitometric scanning of the zymograms of the bone extracts indicated that PTH stimulated only the production of tPA and had no effect on that of uPA. However, PTH also enhanced the release of uPA (both the 48 kD and the 29 kD forms) from the bones into the media. Although inhibiting bone resorption, calcitonin had no effect on the PTH-induced accumulation of PA in bone or on the release of tPA, but it prevented the PTH-induced accumulation of 29 kD uPA in the culture fluids. Thus these studies support the view that tPA and possibly also uPA may have a role in the physiology of bone; the nature of this role remains to be elucidated, however.
Bone mineral density and mass by total-body dual-photon absorptiometry in normal white and asian men
Authors: Russell-Aulet Mary , Wang Jack , Thornton John , Colt Edward W.D. , Pierson Richard N.
Published: February 2010

Total body bone mineral density, total body bone mineral mass (TBBM), and bone mineral densities (BMD) in seven different regions of the body were measured in 238 normal men (154 Whites and 84 Asians), age 22–94, using dual-photon absorptiometry. Although Asian men had lower TBBM and BMD in all regions (p < 0.05) except the arms, when multiple regression was done with body weight, height, and age, no significant differences were found between Asians and Whites for bone measurements. Thus lower bone mineral densities and bone mineral mass in Asian males compared to White males appear to be due to differences in height and weight rather than to ethnic differences. The two groups were combined to derive multiple regression equations for TBBM, total-body BMD, and regional BMD. Age, weight, and height were significant in the multiple regression equations for TBBM, ribs BMD, and legs BMD. Age and weight, but not height, were significant for total-body BMD, trunk BMD, spine BMD, arm BMD, and pelvis BMD. Weight, but neither height nor age, was significant for head BMD. These reference normal bone mineral density and bone mineral mass standards are appropriate for both Asian and White males when adjusted for weight, height, and age.
Tallness versus shrinkage: Do women shrink with age or grow taller with recent birth date?
Authors: Davies K. Michael , Recker Robert R. , Stegman Mary Ruth , Heaney Robert P.
Published: February 2010

This paper presents evidence that much of the high rate of age-related height loss in women reported in cross-sectional studies is actually a cohort effect rather than an aging effect. Data from a large cross-sectional study of healthy, white American women indicate that there has been a gain in peak adult height of 1.0 cm per decade for several decades from 1900 through 1965. Data from the HES, HANES I, and HANES II studies concur on this point. By contrast, data from a longitudinal study of 191 healthy white U.S. women show only a trivial rate of decline from peak adult height in the fifth and sixth decades of life. In an unselected population, some apparent height loss with age is probably due to disease processes, such as vertebral collapse. Caution is needed in using aging to interpret differences in height and in height-dependent variables, such as bone density, in cross-sectional studies.
Expression of the osteonectin gene potentially controlled by multiple Cis- and trans-acting factors in cultured bone cells
Authors: Dominguez Pedro , Ibaraki Kyomi , Robey Pamela Gehron , Hefferan Theresa E. , Termine John D. , Young Marian F.
Published: February 2010

The cis-acting regulatory elements of the osteonectin gene have been studied using a chloramphenicol acetyl-transferase (CAT) promoter assay in osteonectin-expressing and nonexpressing cultured cells. When various stretches of the promoter were transiently transfected into fetal bovine bone cells, a positive element was detected in the DNA located between bases −504 and 11 (1 being the start of transcription) and a negative element between bases −900 and −504. The positive element of the promoter also conferred preferential expression of the gene, showing more activity in cells with higher levels of osteonectin mRNA expression. A 1.2 kb fragment of intron 1 displayed a negative effect on CAT expression when inserted 5′ to the promoter. An additional regulatory element was found in DNA encoding exon 1, which significantly influenced expression of the gene in fetal bovine bone cells. Gel shift analysis using positive genomic elements located 5′ to the start of transcription indicated that one of the nuclear proteins that interacts with the osteonectin promoter may be related to the transcription factor AP2.
Structure-activity relationships in calcitonin gene-related peptide: Cyclic AMP response in a preosteoblast cell line (ks-4)
Authors: Thiebaud Daniel , Akatsu Takuhiko , Yamashita Takeyoshi , Suda Tatsuo , Noda Toshiharu , Martin Rachel E. , Fletcher Ann E. , Prof. Martin T. John
Published: February 2010

Synthetic analogs of chicken and human CGRP were used to define structure-function relationships in a murine osteoblast precursor cell line, KS-4, that exhibits a substantial cyclic AMP response to CGRP but no response to calcitonin. Human CGRP had 40% of the activity of chicken CGRP, but [Asp-14]-human CGRP was equipotent with chicken CGRP. Similar observations were made previously for calcium- and phosphate-lowering effects. Des-1-Ala, deamino CGRP compounds of both human and chicken origin were three-fold more potent than the respective native CGRPs. The [4-F-Phe)-37]-chicken CGRP analog had a four-fold enhanced activity. In all of the 13 analogs either truncated amino-terminally or missing the (2–7)-disulfide bridge, biologic activity was greatly reduced (0.1% of chicken CGRP), as it was in chicken CGRP-(1–36)-OH, which lacks the C-terminal amino acid. The same analog has been shown to retain a hypocalcemic effect, which is most likely mediated through calcitonin receptors. In confirmation of their antagonistic effect reported in liver, analogs that lack the N-terminal ring structure exhibited significant antagonistic activity. The data illustrate the specificity of CGRP receptors in promoting cyclic AMP formation in osteoblast-like cells. Such CGRP analogs will be useful in investigating structure-function relationships of CGRP.
Impairment of gamma carboxylation of circulating osteocalcin (bone gla protein) in elderly women
Authors: Plantalech Louisa , Guillaumont Marc , Vergnaud Philippe , Leclercq Michel , Dr. Delmas Pierre D.
Published: February 2010

Osteocalcin, also called bone gla protein, is a unique noncollagenous protein of the extracellular matrix of bone that circulates in blood. Oseteocalcin contains three residues of the vitamin K-dependent γ-carboxyglutamic acid (gla) responsible for the affinity of osteocalcin for bone mineral. In animals treated with the vitamin K antagonist warfarin, the osteocalcin content of bone is markedly reduced and the fraction of osteocalcin released into the circulation is increased. Most studies have shown that osteocalcin increases with aging in women, reflecting an increase in bone turnover, especially after the menopause. To determine if this increase in osteocalcin could be associated with impaired carboxylation, we measured total and noncarboxylated osteocalcin in the serum of 72 women of various ages: 22 premenopausal (31 ± 7 years old), 20 early postmenopausal (54 ± 3 years), and 30 elderly women (85 ± 8 years). As previously reported, total serum osteocalcin was significantly increased in early postmenopausal and elderly women. Noncarboxylated serum osteocalcin was slightly increased in early postmenopausal women (0.95 ± 0.4 versus 0.65 ± 0.5 ng/ml in premenopausal women), markedly elevated in elderly women (1.59 ± 1.1 ng/ml, p < 0.001), and correlated with age (r = 0.47, p < 0.001). Elderly women had values of the same magnitude as in 10 patients on chronic warfarin therapy (1.94 ± 1.1 ng/ml). As a consequence, the increase in carboxylated serum osteocalcin was significant in early postmenopausal women but not in elderly women. Serum levels of vitamin K1 and of menaquinones 6, 7, and 8 were measured in some of the young and elderly women. No difference was found, which does not suggest a major vitamin K deficiency in elderly women. Conversely, our data may be related to an inadequate recycling of vitamin K or to an intrinsic defect of the carboxylation system within the osteoblasts of elderly people. In conclusion, we have shown that circulating osteocalcin is undercarboxylated in elderly women through an unknown mechanism, suggesting a decrease in the osteocalcin content of bone. Further studies should be conducted to determine the importance of these abnormalities in the pathogenesis of the bone loss occurring with aging.
Role of physical activity in the development of skeletal mass in children
Authors: Dr.P.H. Slemenda Charles W. , Miller Judy Z. , Hui Siu L. , Reister Teresa K. , Johnston C. Conrad
Published: February 2010

A group of 118 children, aged 5.3–14 years, were enrolled in a prospective study of calcium supplementation and bone mass. At entry to the study, questionnaires regarding the child's usual physical activity were administered to the children and their mothers. Repeated activity assessments at 6 month intervals indicated good within-person agreement for total activity and for most individual activities. Consistent positive associations were observed between bone mineral densities (BMD) in the radius, spine, and hip and most activities. A summary measure (total hours of weight-bearing activity) was significantly releated to BMD in the radius and hip, independently of age or gender effects. Self-reported sports and play activities were associated with BMD, but neither time spent watching television nor hours of physical education classes were associated either positively or negatively with skeletal mass. These data suggest that important increments in skeletal mass may result from physical activity during childhood.
Failure to detect paramyxovirus sequences in paget's disease of bone using the polymerase chain reaction
Authors: Ralston Stuart H. , Digiovine Francesco S. , Gallacher Stephen J. , Boyle Iain T. , Duff Gordon W.
Published: February 2010

It is widely believed that Paget's disease of bone is due to a “slow virus” infection of osteoclasts with one of the paramyxovirus group. Controversy continues to surround the identity of the virus involved, however, since at different times evidence has been presented implicating measles virus (MV), respiratory syncytial virus (RSV), and canine distemper virus (CDV) as putative infective agents. In this study we used the technique of reverse transcription and polymerase chain reaction (PCR) to screen for paramyxovirus sequences in ribonucleic acid (RNA) extracted from pagetic bone. We were able to detect viral amplification products of the appropriate size in RNA extracted from as few as 50 cells experimentally infected with a wide range of paramyxoviruses, including measles, canine distemper, parainfluenza 3, and respiratory syncytial virus, but we found no evidence of viral products in RNA extracts of affected bone from 10 consecutive patients with Paget's disease. This study fails to support the hypothesis that active infection with one of these or a related paramyxovirus is involved in the pathogenesis of Paget's disease.
Effects of antiestrogenic compounds on avian medullary bone formation
Authors: Dr. Williams Daniel C. , Paul Donald C , Herring Janice R.
Published: February 2010

Administration of estradiol to male Japanese quail induced the formation of medullary bone in the marrow cavities of the bird's femora and tibiae. This was accompanied by increased serum levels of calcium, phosphorus, and alkaline phosphatase activity. We examined the effects of two structurally distinct “antiestrogens” on the estrogen-induced formation of medullary bone in this quail model. Trioxifene (LY133314) and tamoxifen are members of a group of compounds commonly referred to as antiestrogens that elicit mixed agonist-antagonist actions on estrogen target tissues. In our experiments, these compounds did not display estrogen agonist properties with respect to medullary bone formation. They also did not elicit changes in serum calcium, phosphorus, or alkaline phosphatase activity. When given concurrently with estradiol, the compounds inhibited both the estrogen-induced formation of medullary bone and the associated changes in serum parameters. Trioxifene appears to be somewhat more potent than tamoxifen in antagonizing estrogen effects in this model.
Rapid publication TGF-β1 induces bone closure of skull defects
Authors: Beck L. Steven , Deguzman Leo , Lee Wyne P. , Xu Yvette , McFatridge Lorrie A. , Gillett Nancy A. , Amento Edward P.
Published: February 2010

Transforming growth factor β1 (TGF-β1) is a multifunctional regulatory protein. It is capable of inducing site-specific healing responses by increasing collagen synthesis and deposition as well as remodeling at sites of soft tissue repair. Large bony defects in the skull heal by fibrous connective tissue and never form bone unless osteoinductive bony fragments or powders are placed in the defect. We have found, however, that the single application of human recombinant TGF-β1 in a simple 3% methylcellulose gel to skull defects induced a dose-dependent increase in intramembranous bone formation. Complete bony bridging of defects occurred within 28 days after treatment with 2 μg TGF-β1. Sites treated with vehicle alone did not heal with bone formation but rather contained dense fibrous connective tissue between the defect margins.
Osteoclast-specific monoclonal antibodies coupled to magnetic beads provide a rapid and efficient method of purifying avian osteoclasts
Authors: Collin-Osdoby Patricia , Oursler Merry Jo , Webber David , Dr. Osdoby Philip
Published: February 2010

Osteoclasts are the major cell type responsible for normal and pathologic bone resorption. Obtaining highly purified populations of these multinucleated cells has been problematic, although such populations would greatly facilitate investigations of osteoclast regulation and activity. A new immunomagnetic protocol has been devised to surmount these difficulties, employing avian osteoclast-directed monoclonal antibodies (designated 121F, 35L, and 75B) surface coupled to uniformly small, magnetic polystyrene beads covalently conjugated with sheep antimouse IgG. Presentation of these antiosteoclast antibody-coated beads to mixed cell preparations derived from marrow-depleted, collagenase- and/or trypsin-treated chick tibiae and wing bones, followed by magnetic separation and washing, results in efficient and selective binding of osteoclasts to the immunomagnetic beads within minutes. The specific nature of this bead-cell interaction is further demonstrated by the progressive decline in antiosteoclast antibody-coated bead binding to osteoclasts pretreated with the soluble antiosteoclast antibody and also by the absence of binding to osteoclasts by uncoated beads or beads coated with an irrelevant antibody. Under optimal conditions, these isolations typically yield more than a 100-fold enrichment and greater than a 90% purification of osteoclasts from subpopulations of either predominantly nonviable or viable osteoclasts. Although scanning electron microscopy reveals that immunomagnetically purified and cultured osteoclasts internalize large numbers of the antibody-coated beads, such cells appear unimpaired in their ability to attach to tissue culture plastic or devitalized cortical bone slices and to produce resorption pits characteristic for osteoclasts. Additional studies to ascertain the most effective method for removal (desorption) of antibody-coated beads from magnetically isolated osteoclasts demonstrate that moderate physical agitation is at present the most effective protocol to dislodge antibody-coated beads from the cell surface while maintaining osteoclast viability and function. This immunomagnetic technique therefore provides a gentle method for the isolation of highly purified poplations of osteoclasts from heterogeneous bone cell populations in a rapid, efficient, and selective manner.
Journal of Bone and Mineral Research
Authors: Spiegel Allen M.
Published: February 2010

Primary hyperparathyroidism (PHPT) is characterized by hypersecretion of parathyroid hormone (PTH) leading to hypercalcemia and relative hypophosphatemia. PTH acts by binding to cell surface receptors coupled to G proteins. Cyclic AMP is the classic second messenger of PTH action, but substantial evidence indicates that PTH also acts to stimulate formation of the dual second messengers, inositol trisphosphate and di-acylglycerol, thereby mobilizing intracellular calcium. The physiologic actions of PTH include (1) an increase in extracellular fluid ionized calcium through direct actions on kidney and bone, the classic target organs for PTH, and (2) a decrease in extracellular fluid phosphate primarily through renal action. The pathophysiologic effects of PTH arise from (1) direct actions of PTH on bone and kidney, and possibly on nonclassic target organs, and (2) indirect effects of altered mineral homeostasis. PTH hypersecretion in PHPT can lead to bony demineralization, nephrolithiasis, and hypercalcemic crisis. PHPT may also be associated with mental disturbances, neuromuscular disease, hypertension, and glucose intolerance.
Journal of Bone and Mineral Research
Authors: Ladenson Jack H.
Published: February 2010

Calcium is the most closely controlled substance in the blood. The biologic variation of total calcium is ≈︁ 2% and of the biologically active free (ionized, ionic) calcium only 1%.(1–3) Thus, the monitoring of calcium in blood requires analytic procedures of high precision and accuracy. For patients with asymptomatic primary hyperparathyroidism, calcium monitoring involves the measurement of total calcium and free calcium. This review first considers the measurement of total calcium and then free calcium.
Journal of Bone and Mineral Research
Authors: Peacock Munro
Published: February 2010

Determination of bone mass is currently the most clinically useful measurement of bone strength and of fracture risk. Interpretation of bone mass determination as it relates to fracture has been developed largely from studies of age-related bone loss. A decrease in bone mass and an increase in fracture incidence with aging are universal phenomena that are causally related by virtue of the major contribution bone mass makes to skeletal strength. Over 70% of the skeleton's strength to resist fracture resides in its mineral content in vitro. Clinically, the relationship between trauma and fracture is complex, and in the general population, fracture appears as a random event occurring more frequently as bone mass decreases. In the individual, measurement of bone mass in relation to the range of bone mass and the fracture incidence of the reference population provides an estimate of the risk of sustaining a fracture in the future. In primary hyperparathyroidism, interpretation of a bone mass determination must take into account the effect of the disease activity on the skeleton against the background of universal age-related changes in bone mass and fracture incidence. This general relationship is likely to be altered by at least three unique effects that parathyroid hormone may have on the skeleton: (1) parathyroid hormone has a differential effect on cortical and cancellous bone; (2) it has a biphasic effect on bone that is concentration dependent; and (3) it alters bone quality and architecture. In asymptomatic patients with primary hyperparathyroidism who are considered for long-term medical follow-up, bone mass determination and fracture incidence must be part of the essential monitoring process both to provide a best estimate of fracture risk for the subject and to provide prospective data to refine the estimate of fracture risk for the disease itself.
Journal of Bone and Mineral Research
Authors: Bilezikian John P. , Silverberg Shonni J. , Shane Elizabeth , Parisien May , Dempster David W.
Published: February 2010

Data are presented on 97 patients with primary hyperparathyroidism who constitute a representative cohort of the disease seen today. The average calcium (11.1 ± 0.1 mg/dl; normal 8.7–10.7), phosphorus (2.8 ± 0.1 mg/dl; normal 2.5–4.5), and parathyroid hormone level by immunoradiometric assay (119 ± 7 pg/ml; normal 10–65) are typical of the modern presentation of primary hyperparathyroidism. Most patients were asymptomatic in that there was evidence for nephrolithiasis in only 18% and for radiologically evident bone disease in only 1% of patients. Nevertheless, when patients were evaluated with bone densitometry and with histomorphometric analysis of the bone biopsy specimen, evidence for the hyperparathyroid process could be shown in the majority of patients. Selective reduction of cortical bone and preservation of cancellous bone were apparent. Among patients with nephrolithiasis, no particular feature distinguished them from patients without nephrolithiasis. All biochemical data were similar between both stone and non-stone formers. The selective reduction in cortical bone was seen to the same extent among those with stones as among those without stones. The average 1,25-dihydroxyvitamin D level was not increased among those with stones. When the population was divided into groups with elevated or normal 1,25-dihydroxy vitamin D levels, the incidence of nephrolithiasis was unchanged. The results indicate that bone involvement can be demonstrated among most patients with asymptomatic primary hyperparathyroidism and that no pathophysiologic mechanisms are yet apparent to account for nephrolithiasis in primary hyperparathyroidism.
Journal of Bone and Mineral Research
Authors: Warner J. , Dr. Clifton-Bligh P. , Posen S. , McElduff A. , Delbridge L. , Reeve T.
Published: February 2010

Forearm bone mineral content was measured in 28 patients with primary hyperparathyroidism before and 1 year after successful parathyroidectomy. The forearm bone mineral content rose from a mean value of 1.068 to 1.092 g/cm (P < 0.05, paired /-test). Those patients with the lower initial values had the largest rise. In an additional study, the forearm bone mineral content was measured in 10 women over the age of 40 years (mean age 58.6 ± 7.9SD years) with hyperparathyroidism before and for 2 years after successful parathyroidectomy and compared with the forearm bone mineral content measured over 2 years in 12 women (mean age 56.3 ± 5.5SD years) with continuing hyperparathyroidism and with the forearm bone mineral content of 12 eucalcemic control women (mean age 58.8 ± 8.2SD years), also measured over 2 years. The parathyroidectomized group gained bone, whereas the ongoing hyperparathyroid group and the eucalcemic control group lost bone. The difference between the parathyroidectomized group and the ongoing hyperparathyroid group was significant after 2 years (P < 0.05). The percentage loss of forearm bone mineral in the eucalcemic control subjects was not significantly different from the percentage loss of forearm bone mineral in the ongoing hyperparathyroid group, although the initial mean bone mineral content in the eucalcemic group was significantly higher than in the ongoing hyperparathyroid group, suggesting that a possible determinant of bone mineral loss in women in this age group is the initial bone mineral content.
Journal of Bone and Mineral Research
Authors: Dr. Parfitt Michael A. , Rao D. Sudhaker , Kleerekoper Michael
Published: February 2010

The sustained effects of biochemical screening to increase both apparent incidence and age at diagnosis indicate that, without screening, most patients with primary hyperparathyroidism would never be diagnosed. This suggests that asymptomatic patients discovered as a result of screening have a nonprogressive form of the disease, with adverse health effects that are few or nontraditional, for which treatment policies validated only in symptomatic patients may be inappropriate. Accordingly, in 1975 we formulated criteria for withholding surgical treatment from such patients. Of 174 who were eligible for study over a 10 year period, clinical, biochemical, and densitometric assessment was repeated after at least 1 year (mean 52 months) in 106 patients who did not differ in any initial characteristic from 68 patients in whom follow-up was inadequate. There was no change in symptoms, no disease complications, and no change in any index of hormone secretion or disease severity. In 30 patients, individual regression slopes against time were not significant for any serum measurement. In these patients the disease appeared to have stopped progressing by the time the diagnosis was made, most likely because of cessation of tumor growth. There was a significant deficit in appendicular cortical bone at the time of diagnosis but no further acceleration of bone loss thereafter. In an earlier study, surgical cure was followed by a modest increase in forearm bone density for the first 6 months, but even after 3 years only about 20% of the deficit was corrected. The deficit in bone density is smaller in the spine than in the forearm and is not accompanied by any increase in vertebral fracture risk. Our data suggest that surgery may not be needed to prevent the traditional complications of primary hyperparathyroidism in asymptomatic patients, but our study is weakened by deficiency in follow-up and lack of concurrent control subjects. Also, nontraditional effects on cardiovascular mortality, cancer incidence, and neurobehavioral morbidity were not addressed. Resolution of these uncertainties requires a controlled clinical trial of surgical versus conservative management in these patients.
Journal of Bone and Mineral Research
Authors: Dr. Heath David A. , Heath Eileen M.
Published: February 2010

The personal management of patients seen with primary hyperparathyroidism over the past 10 years has been reviewed; 248 cases were identified of which 122 have been managed conservatively. These patients were mainly asymptomatic. Apart from 4 who developed renal stones, which were spontaneously passed, there was no clinical or biochemical evidence that patients sustained adverse consequences by conservative management. These studies support the need for further studies of the conservative management of asymptomatic hyperparathyroidism.
Journal of Bone and Mineral Research
Authors: Shane Elizabeth
Published: February 2010

Patients with mild asymptomatic primary hyperparathyroidism who do not meet currently accepted guidelines for surgery may be followed medically. General medical management of these individuals should be directed toward maintaining adequate hydration, therapy of hypertension, and avoiding immobilization. Diuretics should be used only with caution. Moderate dietary calcium intake (500–800 mg/day) should be encouraged. Propranolol and cimetidine are not useful in the therapy of primary hyperparathyroidism. Oral phosphate is efficacious in lowering serum and urinary calcium. However, because of concerns related to ectopic calcification, phosphate is usually reserved for those patients who meet surgical guidelines but who are not to undergo surgery. Bisphosphonates, potent inhibitors of osteoclast-mediated bone resorption, have been shown to lower serum and urinary calcium in patients with primary hyperparathyroidism. However, long-term data on their efficacy in this disorder are not yet available. The use of bisphosphonates at the present time is generally restricted to the research setting. More potent bisphosphonates as well as the design of newer agents that interfere with parathyroid hormone secretion may become very useful in future approaches to the medical management of primary hyperparathyroidism.
Journal of Bone and Mineral Research
Authors: Wells Samuel A.
Published: February 2010

Primary hyperparathyroidism was thought 30 years ago to be a rare disease, and the diagnosis was most often made in patients presenting with either bone disease or kidney stones. Today the minority of patients with hyperparathyroidism present with such symptoms, a fact accounted for by the introduction into general medical practice three decades ago of laboratory technology for efficiently determining the serum concentrations of various blood minerals, including calcium. Hypercalcemia was detected more frequently, and it was realized that most patients with hyperparathyroidism either had minor symptoms, such as constipation, polyuria, tiredness, and muscle weakness, or they were “asymptomatic” and indistinguishable from normal subjects. It was thought that primary hyperparathyroidism was a progressive disease and that sooner or later all patients would become symptomatic and require parathyroidectomy. Since this operation was curative in a high percentage of cases, it was recommended for virtually all patients once the diagnosis was established. In this contribution the long-term benefits of parathyroidectomy in patients with and without symptoms from primary hyperparathyroidism are reviewed. It is concluded that a multicenter prospective randomized trial is needed to resolve the indications for operative and nonoperative management of patients with this disease.
Journal of Bone and Mineral Research
Authors: Doppman John L. , Miller Donald L.
Published: February 2010

A number of recently published series were reviewed evaluating noninvasive localizing studies (ultrasound, thallium-technetium subtraction scintigraphy, computed tomography, and magnetic resonance imaging) in patients with primary hyperparathyroidism and no previous surgery. The average true positive (%) and false positive (%) rates were (1) ultrasound, 66 and 12; (2) Th/Tc scanning 55 and 13; (3) computed tomography, 63 and inadequately documented; (4) magnetic resonance imaging, 75 and 18. The success rate of initial operation in this group of patients is over 90%. There is no evidence that preoperative localizing studies shorten operating time or prevent surgical failures. For these reasons, noninvasive localization studies are not indicated in patients with primary hyperparathyroidism before initial surgery.
Development and characterization of a rapidly proliferating, well-differentiated cell line derived from normal adult human osteoblast-like cells transfected with SV40 large T antigen
Authors: Keeting Philip E. , Scott Robert E. , Colvard Douglas S. , Anderson Marlys A. , Oursler Merry J. , Spelsberg Thomas C. , Dr. Riggs Lawrence B.
Published: February 2010

A new bone cell line was established by transfecting normal adult human osteoblast-like (hOB) cells, derived from a 68-year-old woman, with the plasmid pSV3 neo. The plasmid included coding sequences and promotors for the large and small T antigens of the SV40 virus as well as resistance to the antibiotics neomycin and G418. A single antibiotic-resistant colony was located and cloned. Large tumor antigen production in the clonal cell line was confirmed by indirect immunofluorescence study. Treatment with 1,25-dihydroxy-vitamin D3 increased steady-state concentrations of protein and mRNA for osteocalcin and for alkaline phosphatase. Northern blot analyses also demonstrated the presence of mRNAs for α(I)-procollagen, osteopontin 1a, transforming growth factor β, and interleukin-1β. The plasma membrane calcium pump and osteonectin were identified by immunocytochemical analysis. These cells produced a matrix that mineralized when β-glycerophosphate was added to their cultures. As assessed by functional receptor assays, both estrogen and androgen receptors were present and functional, although at low concentrations. Treatment with parathyroid hormone did not stimulate adenylate cyclase activity. Thus, these cells are a well-differentiated, steroid-responsive clonal cell line that closely approximates the phenotype of the mature osteoblast. They should serve as an excellent model for the study of osteoblast biology.
Radial bone mineral changes in pre- and postmenopausal healthy japanese women: Cross-sectional and longitudinal studies
Authors: Hagino Hiroshi , Yamamoto Kichizo , Teshima Ryota , Kishimoto Hideaki , Kagawa Takeshi
Published: February 2010

Healthy premenopausal and postmenopausal Japanese women were evaluated by longitudinal and cross-sectional studies to assess changes in radial bone mineral density. A total of 300 healthy Japanese women were enrolled in the cross-sectional study, and 126 of them were chosen for the longitudinal study. In the cross-sectional study significantly lower bone mineral density was found in the women over 50 years old. In the longitudinal study, premenopausal women aged 45–54 years showed rate of change of -0.61%/year at the distal radius and 0.49%/year at the radial shaft. The perimenopausal changes were –1.95 and -0.93%/year and the postmenopausal changes were –1.88 and –1.37%/year at the distal radius and at the radial shaft, respectively, in the women aged 45–54 years. These rates of premenopausal and postmenopausal change were similar to those reported for whites in the United States. The strength of the relationship between the rate of change in radial bone mineral density and the anthropometric values, biochemical data, and menopausal status was evaluated by multiple linear regression analysis. Menopausal status had the greatest influence on the rate of change in radial bone mineral density. It is concluded that menopausal status was the most important variable related to bone loss in our longitudinal study and the rate of bone loss was greatest during the early postmenopausal period in healthy Japanese women.
Immunohistochemical identification of superoxide dismutases, catalase, and glutathione-s-transferases in rat femora
Authors: Deahl S. Thomas , Oberley Larry W. , Oberley Terry D. , Elwell James H.
Published: February 2010

We used light microscopic immunohistochemistry to locate manganese superoxide dismutase, copper zinc superoxide dismutase, catalase, and glutathione-S-transferases in demineralized femora from rats of 4–14 weeks of age. Immunoblots confirmed the specificity of the polyclonal antibodies for the rat proteins of interest. Each of the enzymes exhibited a unique staining pattern. Copper-zinc superoxide dismutase was detected within some articular and epiphyseal chondrocytes of younger animals. Manganese superoxide dismutase was detected within some articular and epiphyseal chondrocytes, within some osteoprogenitor cells and osteoblasts, within many osteoclasts, and within some vascular smooth muscle cells. Catalase was identified within articular chondrocytes, epiphyseal chondrocytes, and osteocytes, whereas staining at the periphery of hypertrophic chondrocytes suggested extracellular and/or cell membrane-associted catalase. Glutathione-S-transferases were detected within and at the periphery of epiphyseal and articular chondrocytes and less prominently within cortical osteocytes. There were no major age-related changes in antioxidant enzyme distribution.
Interaction of nascent preproparathyroid hormone molecules with microsomal membranes
Authors: Baba Hisamitsu , Karaplis Andrew C. , Wiren Kristine M. , Keutmann Henry T. , Kronenberg Henry M.
Published: February 2010

To characterize the early steps in the interaction of nascent chains of preproparathyroid hormone (prepro-PTH) with the secretory apparatus, such truncated nascent chains still attached to ribosomes were tested for binding to microsomal membranes and cleavage by signal peptidase. Nascent chains of 114, 97, 88, 81, 70, and 59 residues were tested for their ability to bind tightly to membranes and to undergo signal sequence cleavage. Chains of 81 residues and longer bound tightly to the membranes and were cleaved by signal peptidase. The 88- and 81-residue precursors and their corresponding pro-proteins were less efficiently associated with the membranes than were the 114- and 97-residue precursors and their corresponding pro-proteins. The 70-residue chain bound to the membrane but was not cleaved. When this peptide was subsequently released from the ribosome with puromycin, it was cleaved by signal peptidase. The 59-residue chain bound only slightly to the microsomal membrane and was not cleaved by signal peptidase, even when the nascent peptide was released from the ribosome with puromycin. Thus the critical length for productive binding to microsomal membranes is between 59 and 70 residues; the length required for signal cleavage is between 70 and 81 residues.
Expression of insulin-like growth factor I messenger ribonucleic acid in regenerating bone after fracture: Influence of indomethacin
Authors: Edwall Dan , Prisell P.T. , Levinovitz A. , Jennische E. , Norstedt G.
Published: February 2010

Expression of insulin-like growth factor I (IGF-I) was studied during time in the callus formed after tibial fracture in rats. Levels of IGF-I mRNA in callus peaked on the day 8 postfracture, showing a 10- to 15-fold induction compared to control bone. Levels of IGF-I mRNA tended also to be increased in the fracture-adjacent musculus tibialis anterior. IGF-I immunoreactivity was found in cartilaginous cells, osteoblasts, and myocytes 6 and 8 days after fracture. No obvious differences were found between hypophysectomized animals and control animals with regard to IGF-I immunoreactivity. Administration of the antiinflammatory drug indomethacin decreased the IGF-I mRNA expression in the tibial fracture model. Previous findings have shown that IGF-I is activated during in vivo muscle regeneration, and also in this model indomethacin administration reduces the expression of IGF-I. The finding that indomethacin administration reduces IGF-I expression could indicate that an inflammatory response may be important for activation of IGF-I during tissue regeneration.