bluuebunny/crossref_metadata_2025_split huggingface dataset:
Collagen crosslinks and mineral crystallinity in bone of patients with osteogenesis imperfecta
Authors: Vetter Ulrich , Weis Mary Ann , Mörike Martin , Eanes Edward David , Eyre David Rodney 
Published: February 2010

Abstract
In cortical bone samples from patients with osteogenesis imperfecta (OI), the concentrations of hydroxy pyridinium cross-linking amino acids in collagen were measured by reversed-phase HPLC and the x-axis crystallinity of the apatite mineral phase was determined by x-ray diffraction. Bone samples from three patients with type I, nine patients with type III, and eight patients with type IV OI were analyzed and compared with human bone from nine controls. The concentration of the two chemical forms of the mature collagen cross-linking amino acids, hydroxylysylpyridinoline (HP) and lysylpyridinoline (LP), and the ratio HP/LP were found to be alike in bone collagen of OI patients and healthy controls. However, the c-axis crystallinity of the apatite was found to be reduced in the type III and IV OI patients compared with controls. Regression analysis of crosslink concentrations and c-axis crystallinity in OI bones did not show any correlation. Therefore, collagen molecules deposited in the extracellular matrix of OI bone appear to fulfill the structural requirements for the action of the enzyme lysyl oxidase, such that a normal concentration of intermolecular crosslinks is formed compared with healthy bone. Consequently, crosslink formation and apatite crystal growth seem to be regulated independently in OI bone.
Early strain-related changes in cultured embryonic chick tibiotarsi parallel those associated with adaptive modeling in vivo
Authors: Dallas Sarah L. , Zaman Gul , Pead Matthew J. , Lanyon Lance E. 
Published: February 2010

Abstract
A model was developed for the application of cyclic mechanical loads to 17 day embryonic chick tibiotarsi in culture. A single 20 minute period of intermittent loading at 0.4 Hz, producing physiologic peak strains and strain rates, resulted in two peak strain magnitude-related responses that were previously reported in vivo: (1) a rapid increase in glucose 6-phosphate dehydrogenase activity in osteoblasts and osteocytes and (2) increased RNA synthesis, as shown by increased incorporation of [3H]uridine into extracted RNA. The RNA response was detectable 8 h following loading but was more pronounced by 24 h. Both responses were blocked by indomethacin (10−6 M). These results demonstrate that embryonic chick bones in organ culture exhibit cellular responses to loading similar to those previously identified in adult canine cancellous bone cultures in vitro and adult avian cortical bone in vivo. These findings are consistent with a sequence of events between loading and new bone formation that includes an immediate strain magnitude-related, prostanoid-dependent increase in activity of the pentose monophosphate shunt in osteoblasts and osteocytes, followed by a similarly strain magnitude-related increase in RNA synthesis over the subsequent 24 h.
Early loading-related changes in the activity of glucose 6-phosphate dehydrogenase and alkaline phosphatase in osteocytes and periosteal osteoblasts in rat fibulae in vivo
Authors: Dodds Robert A. , Ali Nadire , Pead Matthew J. , Lanyon Lance E. 
Published: February 2010

Abstract
The tibiae and fibulae of 14-week-old rats were subjected to a single 5 minutes period of cyclic longitudinal loading at 1 Hz. The activity of the enzymes glucose 6-phosphate dehydrogenase (G6PD) and alkaline phosphatase (ALP) in osteocytes and periosteal osteoblasts was measured immediately and 24 h after loading. In osteocytes G6PD activity was increased immediately after loading but returned to control values 24 h later. There was no detectable ALP activity in these cells regardless of loading history. In periosteal osteoblasts G6PD activity was raised immediately after loading and remained higher than controls 24 h later. ALP activity in periosteal cells was unaffected immediately after loading but 24 h later was substantially increased. These findings are consistent with osteocytes and periosteal cells both being immediately responsive to periods of intermittent loading in their adjacent matrices. In both cell types an early feature of this response is an increase in G6PD activity. In osteocytes this response is short-lived, suggesting that it is an early biochemical change associated with strain perception that does not progress to matrix synthesis. The increase in G6PD activity with unaffected ALP levels in periosteal cells immediately after loading is consistent with a similar response. In these cells the increase in G6PD accompanied by increased ALP levels 24 h after loading suggests that the loading-related response progresses to new bone formation.
Cross talk of dual-signal transduction systems in the regulation of DNA synthesis by parathyroid hormone in osteoblastic osteosarcoma cells
Authors: Kano Junichi , Sugimoto Toshitsugu , Fukase Masaaki , Chihara Kazuo 
Published: February 2010

Abstract
There has been recent evidence that calcium/protein kinase C (Ca/PKC) messenger system as well as adenylate cyclase are involved in the signal transduction stimulated by PTH. We therefore examined the role of these dual-signal transduction systems and the interaction of these systems in the regulation of DNA synthesis by PTH in the osteoblastic osteosarcoma cells, UMR-106. As recently reported, 10−4 M Sp-cAMPS, a direct activator of cAMP-dependent protein kinase (PKA), and 10−4 M dibutyryl-cAMP, as well as hPTH-(1–34), caused the significant inhibition of [3H]thymidine incorporation (TdR). Both A23187 and ionomycin (10−8-10−6 M) inhibited TdR in a dose-dependent manner, with a minimal effective dose at 10−7 M. Although 10−6 M phorbol 12-myristate 13-acetate (PMA) caused slight but significant stimulation of TdR by itself, it augmented not only dibutyryl-cAMP- but also Sp-cAMPS-induced inhibition of TdR. On the other hand, 4α-phorbol 12,13-didecanoate, incapable of activating PKC, failed to augment these cAMP analogs-induced effects. Pretreatment with 50 μM H-7, an inhibitor of PKC, not only abolished the PMA-induced augmentation of effect by cAMP analogs but also significantly blocked the PTH-induced inhibitory effect on TdR. Pretreatment with 10−6 M PMA, which downregulates PKC, significantly inhibited the PTH-induced suppression of TdR. Combined treatment with cAMP analog (dibutyryl-cAMP or Sp-cAMPS) and calcium ionophore (A23187 or ionomycin) caused additive effects on TdR, and PMA used in combination with both cAMP analog and calcium ionophore induced the further inhibition of TdR. The present study indicated that in addition to the PKA system, the Ca/PKC system also played a contributory role in the full expression of PTH response in the regulation of DNA synthesis in osteoblasts. The present data provided additional evidence for a dual pathway of target cell activation by PTH and the existence of interaction between the adenylate cyclase system and the Ca/PKC system.
Mechanism of action of estrogen on cancellous bone balance in tibiae of ovariectomized growing rats: Inhibition of indices of formation and resorption
Authors: Turner Russell T. , Evans Glenda L. , Wakley Glenn K. 
Published: February 2010

Abstract
Ovariectomy results in cancellous osteopenia in rat long bones, a condition that is prevented by treatment with estrogens. The purpose of these studies was to clarify the effects of estrogen on cancellous bone turnover using dynamic bone histomorphometry. Treatment of ovariectomized rats with diethylstilbestrol (DES) reduced the mineral apposition rate, double-label perimeter, osteoblast number, and osteoclast number, suggesting that the hormone had inhibitory effects on bone formation as well as bone resorption. However, we could not estimate the bone formation rate because of rapid resorption of tetracycline-labeled bone in the ovariectomized rat. The magnitude of loss was documented by a time course study: 58% of the tetracycline initially incorporated into the secondary spongiosa of the tibial metaphysis was resorbed after 11 days and 89% was resorbed after 22 days. Similarly, cancellous bone area was decreased by 67% after 11 days and by 88% after 22 days. Administration of either DES or tamoxifen (TAM) dramatically reduced resorption of tetracycline as well as the decrease in cancellous bone area. These results demonstrate that (1) estrogen prevents osteopenia in ovariectomized (OVX) rats, in part by inhibiting bone turnover, (2) TAM is an estrogen agonist on bone resorption, and (3) resorption of tetracycline-labeled bone leads to serious underestimation of the bone formation rate in OVX rats.
Age- and gender-related changes in body composition in Japanese subjects
Authors: Tsunenari Tohru , Tsutsumi Masaharu , Ohno Kyota , Yamamoto Yoshihiro , Kawakatsu Mitsuru , Shimogaki Kazuhisa , Negishi Hirokuni , Sugimoto Toshitsugu , Fukase Masaaki , Fujita Takuo 
Published: February 2010

Abstract
Age-dependent changes in body composition, namely a decrease in bone mass and lean mass and a reciprocal increase in fat mass, are often observed in normal populations. The recent development of dual-energy x-ray absorptiometry (DXA) made it possible to analyze bone mineral content (BMC), fat mass (fat), and lean body mass (LBM) more precisely and easily. We measured BMC, fat, and LBM in Japanese subjects by DXA to describe the changes in body composition with aging in the Japanese population. A total of 34 female (aged 20–74) and 34 male (aged 18–78) volunteers were divided into three groups according to their age: young (18–22 years), middle-aged (39–48 years), and old (61–78 years). Mean values for body height (BH), body weight (BW), and body mass index (BMI) of the subjects were very similar to Japanese normative values. The BMI of the middle-aged group was the highest of all groups of both sexes. BMC decreased significantly with aging in females but not in males. A decrease in LBM and a reciprocal increase in fat were found between young and middle-aged males but not in females. The correlation between BMC and LBM tends to be greater in males than in females. On the other hand, the correlation between BMC and fat was greater in females than males. These results demonstrate the age- and gender-related difference in body components in Japanese subjects. DXA may be useful for the analysis of body composition in different age and sex groups.
Expression of αv and β3 integrin subunits in rat osteoclasts in situ
Authors: Shinar Doron M. , Schmidt Azriel , Halperin Drora , Rodan Gideon A. , Weinreb Miron 
Published: February 2010

Abstract
Recent findings suggest that the vitronectin receptor, a member of the integrin family, plays an important role in the attachment of osteoclasts to bone matrix. We report here the localization by in situ hybridization of the mRNA for the α and β subunits of the vitronectin receptor in rat bone sections. To generate the rat-specific RNA probes used in this study, we cloned cDNA fragments of integrin chains αv, β3, and β5 by the polymerase chain reaction from rat cDNA. These fragments share 86–91% homology with the respective human sequences. In situ hybridization localized the αv and β3 mRNAs to regions undergoing extensive bone resorption. The histologic appearance and prestaining of bone sections for tartrate-resistant acid phosphatase (TRAP) indicated the presence of these mRNAs in osteoclasts. These observations support immunohis-tochemical findings that osteoclasts express high levels of the vitronectin receptor, confirm the identity of this receptor as integrin αv/β3, and suggest that osteoclasts may actively synthesize these molecules.
Recombinant human transforming growth factor β1 modulates bone remodeling in a mineralizing bone organ culture
Authors: Chen Theresa L. , Bates Rebecca L. 
Published: February 2010

Abstract
Tgf-β1 Increases Cell Proliferation And Collagen Synthesis In Osteoblast-Like Cells And Bone Organ Cultures. However, The Effects Of Tgf-β1 On Bone Resorption Remain Contradictory. Therefore, The Exact Role That This Growth Factor Plays In The Process Of Bone Remodeling Is Still Not Clear. We Studied The Effects Of Recombinant Human Tgf-β1 (Rhtgf-β1) On Bone Formation And Resorption In A Mineralizing Bone Organ Culture System. Parietal Bones From 20-Day-Old Fetal Rat Calvariae Were Cultured Up To 7 Days In Serum-Free BgjB Medium. They Responded To A 1 Day Pulse Or Continuous Treatment Of Rhtgf-β1 With Dose-Dependent Increases In Dry Weight, [3H]thymidine ([3H]TdR) incorporation, and collagen synthesis. In contrast, rhTGF-β, reduced the calcium content of the bones. This is not due to increased bone resorption but rather to failure of calcium deposition. The following responses occurred at 1 nM rhTGF-β1. Dry weight was increased 25–50% after 6 days in culture. DNA synthesis was increased to a maximum at day 1, reaching twofold of the control level. Adding hydroxyurea at day 0 reduced [3H]TdR incorporation in rhTGF-β, treated bones to 20% of the control and indomethacin abrogated the increase in [3H]TdR stimulated by rhTGF-β1 to the control level. Both treatments completely blocked the increase in dry weight induced by rhTGF-β1 at day 6. rhTGF-β1 stimulated collagen synthesis to reach its maximum at day 2, with a twofold increase in [3H]proline incorporation. Basal alkaline phosphatase activity fell continuously in culture, reaching 35% of day 0 level at day 6. Enzyme activity was not altered by rhTGF-β1. Morphologic observations by light and electron microscopy confirmed these findings. In summary, rhTGF-β1 altered bone remodeling by increasing organic components and decreasing calcification in a mineralizing bone organ culture system.
Bone formation periods studied with triple tetracycline labels in women with postmenopausal osteoporosis
Authors: Ott Susan M. 
Published: February 2010

Abstract
In Adult Cancellous Bone, Cyclic Remodeling Occurs In Discrete Locations (Bmus, Or Basic Multicellular Units). Some Aspects Of These Remodeling Cycles Are Still Not Clear. Only About Half The Osteoid Surface Normally Has Tetracycline Labels; The Remainder Is Thought To Be Immature Or In A Resting Phase. This Study Was Designed To Test The Assumption That Pauses Occur During The Bone Formation Periods. Iliac Crest Bone Biopsies Were Performed In 84 Women With Postmenopausal Osteoporosis. The Subjects Were Given Three Tetracycline Labels; The Middle Label Had A Distinctive Color. The Osteoid Surface Was 10 s± 6% Of The Bone Surface; The Range Was 0.6–24.4%. The Mineralizing Surface Was 42 ± 26% Of The Osteoid Surface. Immature Osteoid Was 7.6 ± 5.3% Of The Osteoid Surface. There Were No Bmus With The First And Third Tetracycline Label But Without The Middle Demeclocycline Label. The Expected Length Of Double 1–3 Label, Based On An Assumption That Unlabeled Mature Osteoid Was Temporarily In A Resting Phase, Was Significantly Higher Than The Observed Length (68 ± 77 μm/Mm2 tissue area versus 0, p &lt; 0.0001). The mean active formation period was 77 ± 16 days calculated by standard methods but was only 55 ± 26 days when calculated by label escape (p &lt; 0.001). The correlation coefficient between these two methods was only modest (r = 0.27, p &lt; 0.01). The failure to find any double 1–3 labels despite abundant triple labels provides strong evidence against the presence of pauses in bone mineralization between 3 and 34 days. Adjusting the formation period or the mineral apposition rate by the mineralizing surface/osteoid surface ratio may not be valid in women with osteoporosis.
Bone mineral density and parameters of bone metabolism in patients with acromegaly
Authors: Kotzmann Harald , Bernecker Peter , Hübsch Peter , Pietschmann Peter , Woloszczuk Wolfgang , Svoboda Thomas , Geyer Georg , Luger Anton 
Published: February 2010

Abstract
To Assess The Effect Of Chronically Elevated Plasma Growth Hormone (Gh) Levels On Bone Metabolism And Bone Mineral Density (Bmd), 16 Patients (10 Females And 6 Males) With A Mean Age Of 49.1 ± 13.2 Years (Range 33–68) With Active Acromegaly Were Studied And Compared To A Control Group Of 16 Sex- And Age-Matched Subjects. Bmd Of The Lumbar Spine And Two Different Sites Of The Proximal Femur Were Measured By Dual-Energy X-Ray Absorptiometry (Norland Xr-26). In The Acromegalic Patients The Mean Plasma Gh Concentration Was 30.1 ± 11.1 μg/Liter, And The Mean Plasma Somatomedin C (Smc) Concentration Was 6.5 ± 1.5 U/Liter. Mean Serum Osteocalcin (Oc) Levels (14.3 ± 1.1 Versus 7.2 ± 0.4 Ng/Ml, P &lt; 0.001) As Well As The Urinary Hydroxyproline Excretion (Ohp; 8.8 ± 1.4 Versus 2.7 ± 0.3 Mg, P &lt; 0.0001) Were Significantly Higher In The Acromegalic Patients Than In The Control Subjects. In The Acromegalic Patients Bmd Was Significantly Elevated In The Two Examined Regions Of The Proximal Femur, That Is, The Femoral Neck (1.06 ± 0.05 Versus 0.86 ± 0.03 G/Cm2, p &lt; 0.05) and Ward's triangle (0.92 ± 0.06 versus 0.76 ± 0.03 g/cm2, p &lt; 0.02), whereas the BMD of the lumbar spine was not significantly different from that of control subjects. Among the patients with acromegaly a significant positive correlation between serum OC concentrations, on the one hand, and urinary OHP excretion (r = 0.7, p &lt; 0.004) as well as BMD in the proximal femur (r = 0.64, p &lt; 0.007), on the other hand, could be observed. We therefore conclude that in acromegaly bone turnover (formation and resorption) is increased and, moreover, that BMD is significantly enhanced in the proximal femur but not in the lumbar spine.
Regulation of expression of the chondrocytic phenotype in a skeletal cell line (CFK2) in vitro
Authors: Bernier Suzanne M. , Dr. Goltzman David 
Published: February 2010

Abstract
We Have Examined In Vitro The Spontaneous And Regulated Expression Of Phenotypic Characteristics Associated With Differentiated Chondrocytes In An Established Skeletal Cell Line (Cfk2) Derived From Fetal Rat Calvariae. Extended Culture Of Cfk2 Cells Resulted In The Appearance Of Glycosaminoglycans And Type Ii Collagen In The Cell Layer In Association With The Formation Of Focal Nodes Of Cells. In Addition, Induction Of Mrna-En-Coding Link Protein, Cartilage-Specific Proteoglycan Core Protein, And Thrombospondin Was Observed In The Differentiated Population (Dcfk2 Cells). The Expression Of These Mrnas Was Present For At Least Two Passages After Subculturing The Dcfk2 Cells. The Dcfk2 Cells Also Demonstrated Enhanced Parathyroid Hormone (Pth)-Stimulated Adenylate Cyclase Activity. Proliferation Of Cfk2 Cells Was Stimulated By The Peptide Regulatory Factors Egf And Pth And Inhibited By The Steroidal Agents Dexamethasone And Retinoic Acid. Egf And Retinoic Acid Inhibited The Formation Of Cell Foci And Glycosaminoglycan Deposition And The Expression Of Mrna-Encoding Link Protein. In Contrast, Pth And Dexamethasone Enhanced The Formation Of Focal Cellular Nodes And Augmented Matrix Deposition And Link Protein Mrna Expression. These Studies Therefore Show That The Cfk2 Cell Line Can Serve As A Nontransformed Model Of Rat Chondrocytic Cells In Which Both Induction And Regulation Of The Expression Of Cartilaginous Matrix Components Can Be Observed. This Line Thereby Provides A Unique Renewable Source Of Chondrocytic Precursor Cells And An Excellent In Vitro Model For Evaluating Temporal And Environmental Control Of Chondrocyte Differentiation And Cartilage Matrix Production.
Integrin expression in human bone
Authors: Hughes D.E. , Salter D.M. , Dedhar S. , Simpson R. 
Published: February 2010

Abstract
Integrins are a family of heterodimeric transmembrane glycoproteins that are known to mediate cell-cell and cell-matrix interactions. Members of the VLA (very late activation) family, which consists of β1 integrin in association with the VLA α chains (α1–6), mediate adhesion of a wide range of cells to matrix proteins, such as fibronectin, collagen, and laminin, and may therefore be important for cell-matrix interactions in bone. Integrin expression in human bone was studied immunohistochemically using cryostat sections of fracture callus, tumor-associated reactive bone, and neonatal costochondral junctions, with a panel of well-characterized antibodies against β1–4 integrins, α1–6 and αv integrins, and the αvβ3 dimer (the classic vitronectin receptor). All cell types present in bone expressed β1 and α5 integrins; a subpopulation of osteoblastic cells expressed α4. The αv was uniformly expressed by osteoblasts but was heterogeneously expressed by osteocytes. Osteoclasts also expressed α2, αv, and αvβ3. These results demonstrate differential expression of a restricted range of integrins in bone. This supports the possibility that integrins may mediate the differing interactions of cells of the osteoblast and osteoclast lineages with the matrix of bone.
Bone mineral density and mass in a cross-sectional study of white and asian women
Authors: Russell-Aulet Mary , Wang Jack , Thornton John C. , Colt Edward W.D. , Pierson Richard N. 
Published: February 2010

Abstract
The literature suggests that Asians have lower bone mineral density and mass than whites. It has been proposed that these differences may be due to differences in height, weight, and factors other than ethnicity, but no study has made the appropriate direct comparisons. We compared total-body bone mineral density and mass between Asian and white women while controlling for factors known to be associated with bone mineral density and mass. Measurements were made in 129 Asian (primarily of Chinese ancestry) and 274 white women. A subgroup was formed of women who did not have a history of alcoholism, premenopausal amenorrhea, kidney disease, estrogen use, birth control pill use, thyroid disease, steroid use, hysterectomy, or smoking. In both the main group and the subgroups, bone mineral mass was significantly lower in Asian than in white women, but after analysis of covariance with body weight, height, and age (or years since menopause) as covariates, the differences between ethnic groups disappeared, except in the large group of premenopausal women, in whom average bone mineral density in Asians actually exceeded (p &lt; 0.04) that in whites. The data set was also searched for Asian-white pairs who matched on 17 characteristics related to bone mineral density and mass. In the resulting 16 matched pairs, bone mineral density and mass were not different between ethnic groups. Although Asian women have lower bone mineral mass than white women, when weight, height, and other factors are controlled, bone mineral density and mass do not differ between Asian and white women.