bluuebunny/crossref_metadata_2025_split huggingface dataset:
Influence of lactation and pregnancy + lactation on mechanical properties and mineral content of the rat femur
Authors: Peng Tai-Chan , Kusy Robert P. , Garner Sanford C. , Hirsch Philip F. , De Blanco Maria C. 
Published: February 2010

Abstract
The quality of bone was assessed from femurs of rats both during lactation and after pregnancy + lactation. Mechanical properties of stiffness, strength, toughness, and ductility were measured, along with standard measurements of dry weight, ash weight, and total bone mineral. No changes occurred during the first week of lactation. During the second and third weeks of lactation all bone parameters except ductility decreased significantly. These data are consistent with bone losing mineral in order to supplement the dietary calcium intake necessary for milk production. In other experiments, femurs were collected from nulliparous rats and from rats that had previously undergone 1–3 pregnancy + lactations. The largest changes in bone mineral and mechanical properties occurred after a single pregnancy + lactation period, although significant further decreases in stiffness and strength occurred after the second pregnancy + lactation. No additional losses occurred following the third pregnancy + lactation. Even 5 months after only one pregnancy + lactation period, the bone quality was still impaired as all bone properties were lower than in nulliparous controls. Because the changes, especially stiffness and strength, were relatively larger than the changes in dry and ash weights of bone, measurements of these mechanical properties provide a more sensitive method to evaluate the quality of bone.
Mechanism of fibroblast attachment to bone extracellular matrix: Role of a 44 kilodalton bone phosphoprotein
Authors: Dr. Somerman Martha J. , Prince Charles W. , Sauk John J. , Foster Ruth A. , Butler William T. 
Published: February 2010

Abstract
While the exact mechanisms regulating bone homeostasis are unknown, it is generally accepted that factors with the capacity to regulate cell attachment and spreading play a role in osteogenesis. A 44 kDa bone phosphoprotein (44K BPP), isolated from rat bone and synthesized by osteoblasts, was evaluated for its role in attachment and spreading of fibroblasts. In uncoated plates, enhanced cell attachment and spreading were observed when fibroblasts were exposed to the 44K BPP. The attachment properties of the bone phosphoprotein are different from those of fibronectin, in that the 44K BPP did not promote cell attachment in type I collagen wells, as was seen with fibronectin. Also, 44K BPP continued to enhance cell attachment up to 24 h, whereas cell attachment declined in time with cells exposed to fibronectin. Cycloheximide did not alter 44K BPP promotion of cell attachment, indicating that de novo protein synthesis was not required. These studies suggest that the 44K BPP is important in the regulation of cell attachment and spreading at sites of mineralization.
Effect of epidermal growth factor infusion on serum and urine calcium in mice
Authors: Dr. Shevrin Daniel H. , Lad Thomas E. , Kukreja Subhash C. 
Published: February 2010

Abstract
Transforming growth factors (TGFs) have been implicated in the pathogenesis of the hypercalcemia in malignancy (HM). In order to evaluate the role of these growth factors (epidermal growth factor (EGF) and TGF-α acting via the EGF receptor) in the development of HM, we studied the effect of 2 doses of EGF (0.1 and 0.3 μg/g/day) given for 7 days as a continuous infusion on serum and urine calcium in athymic mice. These infusions had no effect on serum and urine Ca values in this study. In order to assess the biological activity of the infused EGF, other known effects on gastric and pancreatic weights were evaluated. EGF-infused animals had significantly greater gastric and pancreatic weights than controls. Thus, EGF infusion into mice in doses which elicited known biological effects failed to have an effect on serum and urine Ca. An infusion of bovine parathyroid hormone 1–34 at the dose of 0.1 μg/g/day resulted in significant hypercalcemia.
The effect of low calcium diet, mithramycin, and dichlorodimethylene bisphosphonate on humoral hypercalcemia of malignancy in nude mice transplanted with the canine adenocarcinoma tumor line (CAC-8)
Authors: Dr. Rosol T.J. , Capen C.C. 
Published: February 2010

Abstract
The effect of a low calcium diet, mithramycin, or dichlorodimethylene bisphosphonate were evaluated in nude mice with humoral hypercalcemia of malignancy associated with the transplanted canine adenocarcinoma (CAC-8). Low calcium (0.01%) diet significantly reduced serum calcium levels in hypercalcemic nude mice and reduced urine calcium excretion to control levels. Mithramycin (8 mg/kg) decreased serum calcium concentration and urine calcium excretion to the range of control non-tumor-bearing nude mice at day 5 after a single injection, but there was no change in the number of tartrate-resistant acid phosphatase-positive osteoclasts in lumbar vertebrae. Osteoclasts from CAC 8-bearing nude mice after mithramycin administration were decreased in size, had small ruffled borders, and increased relative size of clear zones. Dichlorodimethylene bisphosphonate (Cl2MDP) (45 mg/kg) partially reduced serum calcium concentration of hypercalcemic tumor-bearing nude mice, decreased urine calcium excretion to control levels, and markedly reduced the numbers of tartrate-resistant acid phosphatase-positive osteoclasts in lumbar vertebrae. Osteoclasts from Cl2MDP-treated nude mice were smaller and had a reduced frequency of ruffled borders than saline-treated hypercalcemic nude mice. In vitro bone resorption induced by CAC-8 extract was significantly reduced by C12MDP and mithramycin. The results of these investigations suggest that the hypercalcemia and hypercalciuria associated with HHM in nude mice with CAC-8 are the combined result of altered calcium homeostasis in the bone, kidney, and intestine. Chemotherapeutic agents that specifically affect only bone or feeding a low calcium diet alone may not completely ameliorate the hypercalcemia of HHM.
Procollagen type I carboxy-terminal extension peptide in serum as a marker of collagen biosynthesis in bone. Correlation with iliac bone formation rates and comparison with total alkaline phosphatase
Authors: Parfitt A.M. , Simon L.S. , Villanueva A.R. , Krane S.M. 
Published: February 2010

Abstract
We measured iliac bone formation rates on all surfaces after double tetracycline labeling, serum levels of type 1 procollagen carboxy-terminal extension peptide (pColl-I-C), and serum levels of total alkaline phosphatase activity (TAP) in four normal subjects and in 44 patients with various forms of metabolic bone disease. In three patients with enzymatic evidence of liver disease both biochemical serum markers were disproportionately raised. In a patient with idiopathic axial osteosclerosis serum pColl-I-C was selectively increased by more than ten-fold. In the remaining 44 subjects pColl-I-C and TAP levels correlated significantly with each other (r = 0.70) and both showed the same directional changes and broadly similar correlations with iliac bone formation rate expressed in different ways. In general, pColl-I-C levels correlated better with cancellous bone formation rates and TAP levels with cortical bone formation rates. There was a modest improvement in prediction of bone formation rate with multiple regression using both markers. In 15 patients with typical uncomplicated postmenopausal osteoporosis, neither biochemical marker, singly or jointly, correlated significantly with any expression of bone formation rate. Disadvantages to the use of pColl-I-C as a marker include a significant contribution to the serum level from type 1 collagen biosynthesis in tissues other than bone, and (probably) variable metabolic clearance. For both biochemical markers the most consistently high correlations (r = 0.77–0.79) were found with total bone formation rate for the entire biopsy core volume, which is the best estimate available from a biopsy of formation rate at the bone organ level of organization in vivo. The core volume as a referent also allows the amount of bone formed on cortical, endocortical, and cancellous surfaces to be compared. Measurement of serum pColl-I-C levels merits further study as a noninvasive index of bone metabolism. Differences between normal and abnormal subjects in the relationships between a variety of biochemical markers and a variety of histologic indices have the potential for providing insight into the pathogenesis of osteoporosis.
Tamoxifen prevents the skeletal effects of ovarian hormone deficiency in rats
Authors: Turner Russell T. , Wakley Glenn K. , Hannon Kathleen S. , Bell Norman H. 
Published: February 2010

AbstractTo determine whether the nonsteroidal antiestrogen tamoxifen behaves as either an agonist or antagonist of estrogen on bone, the effects of ovariectomy, 17β-estradiol, and tamoxifen were compared on radial growth at the tibial diaphysis in young adult female rats. Ovariectomy and 17β-estradiol did not alter serum calcium, phosphate, or 25-hydroxyvitamin D. Ovariectomy increased serum 1,25-dihydroxyvitamin D in one experiment but not in the other. Tamoxifen increased the serum calcium and phosphate by itself and did not change serum 1,25-dihydroxy vitamin D in ovariectomized rats. Ovariectomy produced significant increases in medullary area, periosteal bone formation rate, and periosteal bone apposition rate compared to values in sham-operated animals and did not change endosteal bone formation rate. The increase in medullary area resulted from an increase in osteoclast number and resorbing surface length. Although endosteal forming surface length decreased, this was compensated for by an increase in the apposition rate. 17β-estradiol and tamoxifen each prevented the increases in bone formation rate and medullary area in ovariectomized rats. Tamoxifen reduced the length of the resorbing surface and osteoclast number to values observed in sham-operated animals. The findings demonstrate that in the rat, tamoxifen acts as an estrogen agonist by preventing the skeletal alterations that result from ovarian hormone deficiency.
J774A.1 macrophage cell line produces PDGF-like and non-PDGF-like growth factors for bone cells
Authors: Cheng S. -L. , Rifas L. , Shen V. , Tong B. , Pierce G. , Deuel T. , Peck William A. 
Published: February 2010

Abstract
In light of evidence that macrophages participate in the local regulation of bone remodeling, we have examined the production of peptide stimulators of bone cell growth and specialization by the J774A.1 macrophage cell line. Cultured J774A.1 cells secrete growth-promoting activities which have an affinity for heparin. The first partially purified materia), termed HEP I, appears to contain platelet-derived growth factor (PDGF)-like activity. It has a molecular weight of about 30,000 daltons, inhibits the binding of labeled PDGF to its receptors, reacts with polyclonal anti-human PDGF antibody, and exhibits mitogenic activity for osteoblasts, which is partially blocked by anti-PDGF antisera. Like PDGF, HEP I is active in a wide variety of mesenchyme-derived cells, including osteoblasts, chondrocytes, smooth muscle cells, fibroblasts, 3T3 cells and NRK cells. The J774A.1 cells contain mRNA, which hybridizes to a v-sis DNA probe, suggesting that they express the c-sis gene, which contains the code for a PDGF-like protein. The second factor, HEP II, has an approximate molecular weight of 20,000 daltons and possesses substantial mitogenic activity for osteoblasts, chondrocytes, and smooth muscle cells, but is not mitogenic for fibroblasts, 3T3 cells, and NRK cells. HEP II appears to be a unique bone cell mitogen, which is distinct from the growth factors presently known. Neither HEP I nor HEP II contained interleukin 1, a macrophage product known to promote bone resorption and perhaps the growth and activity of osteoblasts.
Total bone calcium in normal women: Effect of age and menopause status
Authors: Gallagher J.C. , Goldgar D. , Moy Alan 
Published: February 2010

Abstract
Bone density in different regions of the skeleton was measured in 392 normal women aged 20–80 years by dual photon absorpiometry. In premenopausal women, aged 25–50 years, multiple regression analysis of regional bone density on age, height, and weight showed a small significant decrease in total bone density (&lt;0.01) but no significant change in other regions of the skeleton. In postmenopausal women there were highly significant decreases in all regions of the skeleton (p &lt; 0.001), and bone density in these areas decreased as a logarithmic function of years since menopause.
Based on multiple regression analyses, the decrease in spine density and total bone calcium was 2.5–3.0 times greater in the 25 years after menopause than the 25 years before menopause. The largest change, however, occurred in the first five years after menopause. During this time the estimated annual change in spine density and total bone calcium was about 10 times greater than that in the premenopausal period. These results demonstrate the important effect of the menopause in determining bone mass in later life.
Bone turnover in spinal osteoporosis
Authors: Pødenphant Jan , Johansen Julia Sidenius , Thomsen Karsten , Riis Bente Juel , Leth Arne , Christiansen Claus 
Published: February 2010

Abstract
We have investigated biochemical indices of bone formation and bone resorption: serum alkaline phosphatase (sAP) plasma bone Gla protein (pBGP), fasting urinary hydroxyproline corrected for creatinine (FuHP/Cr), and fasting urinary calcium corrected for creatinine (FuCa/Cr) in 43 postmenopausal women with spinal fractures. Furthermore, histomorphometric indices of bone resorption and bone formation, as well as whole body retention (WBR) of 99m-technetium-diphosphonate (99mTc-DP), were determined. The results are compared to pre- and postmenopausal normal subjects. The results showed that indices of bone formation were mutually correlated except for sAP vs. WBR. sAP, WBR, and pBGP increased with age. sAP and WBR were not different between osteoporotics and age-matched controls, while pBGP and probably histological indices of bone formation were lower in osteoporotics than in age-matched controls. pBGP—and to a lesser extent sAP—were significantly correlated with all histological parameters reflecting bone formation. Finally, biochemical indices of bone resorption were high in osteoporotic patients and poorly correlated with histological bone resorption. The discrepancy between biochemical markers of bone formation may be related to the low sensitivity of sAP and WBR. Conversely, pBGP, sAP, and WBR may reflect different aspects of osteoblastic activity and bone mineralization. Finally, our data suggest that bone turnover increases with aging and that osteoporotic patients have higher bone resorption and probably lower bone formation than age-matched controls.
Evidence that stimulation of 1,25(OH)2D3 production in primary cultures of mouse kidney cells by cyclic AMP requires new protein synthesis
Authors: Korkor Adel B. , Gray Richard W. , Henry Helen L. , Kleinman Jack G. , Blumenthal Samuel S. , Garancis John C. 
Published: February 2010

Abstract
When primary culture of C75BL6 mouse cortical kidney cells in serum-free medium were incubated with unlabeled 25(OH)D3, they produced a metabolite which co-migrated with authentic 1,25(OH)2D3 and which could be measured by competitive receptor assay. A metabolite co-migrating with authentic 10-oxo-19-nor-25-OH-D3 was also produced. However, when cultures were incubated with 25(OH)D3 for 1 hour or longer, 10-oxo-19-nor-25-OH-D accounted for less than 15% of the total 3H-1,25(OH)2D3 displacement activity. Production of 1,25(OH)2D3 increased with increasing protein content of the cultures, with time of incubation, and with substrate concentration. The apparent Km was 1.4 ± 0.6 μM and Vmax 2.6 ± 0.4 pM/mg protein/hr. These cultures possessed a very high level of phosphodiesterase activity, as indicated by their high cyclic AMP (cAMP) response to IBMX. This high phosphodiesterase activity may have been responsible for the lack of stimulation of 1,25(OH)2D3 production by physiologic or near physiologic concentrations of parathyroid hormone (PTH) in the absence of IBMX. However, when IBMX 10−6M was present, bPTH 10−9M significantly increased production of both cAMP and 1,25(OH)2D3. There was a close correlation between 1,25(OH)2D3 production and cAMP content of the cultures (basal or stimulated). An incubation time of at least 4 hours was required for cAMP to increase 1,25(OH)2D3 production and was inhibited in the presence of cycloheximide and actinomycin D. This study further documents the regulation of renal 1,25(OH)2D3 synthesis by PTH in mammalian kidney and provides evidence for cAMP as a possibly important second messenger in this effect. The synthesis of 1,25(OH)2D3 in response to cAMP appears to depend upon the ability of the cell to synthesize new protein.
Interleukin-1β is a potent inhibitor of bone formation in vitro
Authors: Dr. Stashenko Philip , Dewhirst Floyd E. , Rooney Monique L. , Desjardins Laurie A. , Heeley John D. 
Published: February 2010

Abstract
The effect of interleukin-1β, the major component of osteoclast-activating factor (OAF), on bone formation by fetal rat osteoblast-rich cells was investigated. An in vitro culture system developed by Ecarot-Charrier et al. (1983) and Bellows et al. (1986) was utilized in which osteoblasts form mineralized nodules which closely resemble woven bone. Continuous exposure of cultures to homogenous IL-1β resulted in potent inhibition of mineralized nodule formation, which was half maximal at 0.1 U/ml (7.5 × 10−13M). Bone formation may thus be considerably more sensitive to IL-1β than is bone resorption (half maximal at 3.8 × 10−11M). Inhibition of bone formation occurred when cultures were exposed to IL-1β at both early and late time periods and was unaffected by the presence of indomethacin or by the osteoclast inhibitors calcitonin and γ-interferon. Instead, IL-1β exerted multiple inhibitory effects on osteoblast functions, including inhibition of collagen and noncollagen protein synthesis, alkaline phosphatase expression, and cell replication. On a dose response basis, the inhibition of protein synthesis correlated most closely with inhibition of bone formation. IL-1β is clearly inhibitory rather than stimulatory for bone formation as assessed in this system and is therefore unlikely to function as a coupling factor linking the processes of bone resorption and bone formation.
Production of hemopoietic growth factors by bone tissue and bone cells in culture
Authors: Dr. Felix R. , Elford P.R. , Stoercklé C. , Cecchini M. , Wetterwald A. , Trechsel U. , Fleisch H. , Stadler B.M. 
Published: February 2010

Abstract
This study was carried out to determine whether bone might be a source of hemopoietic growth factors. Both neonatal murine calvaria and primary cultures of cells isolated from calvaria released, upon stimulation with lipopolysaccharide, an activity that stimulated the growth of the interleukin (IL) 3-dependent cell lines, 32D cl, 123, and NSF 60. Upon gel filtration, this activity eluted with a molecular weight of 30,000 kDa. Further characterization, however, revealed that the major activity in conditioned medium was not IL 3. Activity was absorbed by DEAE-Sephacel at low salt concentration, whereas IL 3 does not adhere. Furthermore, an IL 3-specific antiserum did not neutralize the activity from cells and only partly neutralized the activity generated by whole calvaria. After gel filtration, the 30-kDa activity stimulated the growth of very large colonies in semisolid medium consisting mainly of granulocytes with the remainder being macrophages. No colony types belonging to other hemopoietic lineages were found, indicating, again, that the activity was not identical to IL 3. Subsequently, conditioned medium was fractionated by hydrophobic chromatography on Phenyl-Sepharose CL-4B, yielding two peaks of activity. Neutralization of activity with antisera to granulocyte-macrophage colony-stimulating factor (GM-CSF) and IL 3 and use of colony assays showed that medium conditioned by whole calvaria contained GM-CSF and granulocyte CSF (G-CSF) in similar amounts together with a little IL 3, and medium conditioned with calvaria cells contained GM-CSF and little G-CSF. We conclude that bone releases hemopoietic growth factors that could contribute both to hemopoiesis and to the recruitment of osteoclasts from progenitors resident in the adjacent marrow.
Bone status of senescent male rats: Chemical, morphometric, and mechanical analysis
Authors: Kiebzak Gary M. , Smith Ronald , Gundberg Caren C. , Howe Juliette C. , Sacktor Bertram 
Published: February 2010

Abstract
The bone status of male rats 6, 12, and 24 months of age (n = 10) was examined. Femur calcium (Ca), phosphorus (P), and osteocalcin contents; serum chemistry; and mechanical properties of the bone were measured and correlated. Diaphyseal Ca, P, and osteocalcin contents were not different in animals 6 and 12 months of age but decreased significantly at 24 months: -7.4% for Ca, -4.2% for P, and -24% for osteocalcin compared to 12 months. Femurs from 24-month-old (senescent) rats were characterized by a scalloped appearance of the midfemoral endosteal surface and by cortical porosities. These age-associated changes coincided with nearly two-fold increases in serum immunoreactive parathyroid hormone (PTH) and osteocalcin. Serum Ca did not change with age, whereas serum P decreased (-14.8%) from 6 to 24 months. Maximum breaking force required to fracture femurs at midshaft did not change with age. Hence, the strength of the femur as an intact organ was not compromised with age despite the loss of diaphyseal Ca and P in the senescent animal. However, ultimate stress, a parameter that normalizes for differences in bone geometry and size, decreased 35% in femurs from 12- compared with 24-month-old animals. These mechanical results might be explained by the morphometric finding that, in contrast to the small but progressive age-associated increases in femur weight and length, the cortical and medullary areas increased at least two-fold. Therefore, the strength of the intact femur was maintained by architectural compensations, even though normalized tissue strength decreased with age. These findings suggest that bone status was compromised in the aged male rat.
1,25-dihydroxyvitamin D3 stimulates avian and mammalian cartilage growth in vitro
Authors: Burch Warner M. , Lopez-Claros Marcelo , Uskokovic Milan R. , Drezner Marc K. 
Published: February 2010

Abstract
We addressed the question of whether 1,25-dihydroxyvitamin D3 (1,25-(OH)2D) could directly stimulate cartilage growth in vitro. Pelvic leaflets from chick embryos and scapular growth plates from fetal pigs were organ cultured in serum-free medium in the presence and absence of 1,25-(OH)2D. After 3 days of incubation, 1,25-(OH)2D had increased the pelvic cartilage wet weight 42% and the dry weight 32% above the weight of cartilages incubated in medium alone. 1,25-(OH)2D (10−9M-10−12M) caused a dose-dependent increase in weight, with maximal increases at 10−9M. Furthermore, two deuterized derivatives of 1,25-(OH)2D, 26,27-D6-1,25-(OH)2D3 and 24,26,27-D8-1,25-(OH)2D3, stimulated pelvic cartilage growth in vitro. 26,27-D6-1,25-(OH)2D3 increased cartilage growth at concentrations as low as 10−13M. Growth plates from fetal pig scapulas were weighed then organ-cultured for 2 weeks in the presence and absence of 1,25-(OH)2D. 1,25-(OH)2D stimulated increases in growth plate weight above growth plates incubated in medium alone. 26,27-D6-1,25-(OH)2D3 appeared to be potent at lower concentrations than 1,25-(OH)2D on growth plate cartilage. Thus, 1,25-(OH)2D stimulated in vitro growth in two growing cartilage models, the avian pelvic cartilage and the mammalian scapular growth plate cartilage.