bluuebunny/crossref_metadata_2025_split huggingface dataset:
Polarity of Osteoblasts and Osteoblast-like UMR-108 Cells
Authors: Ilvesaro Joanna , Metsikkö Kalervo , Väänänen Kalervo , Tuukkanen Juha 
Published: April 2006

Abstract
Enveloped viruses, such as vesicular stomatitis virus (VSV) and Influenza virus, have been widely used in studying epithelial cell polarity. Viral particles of VSV-infected epithelial cells bud from the basolateral membrane, which is in contact with the internal milieu and the blood supply. Influenza-infected cells bud viral particles from the apical surface facing the external milieu. This feature can be utilized in labeling polarized membrane domains. We studied the polarity of mesenchymal osteoblasts using osteosarcoma cell line UMR-108 and endosteal osteoblasts in situ in bone tissue cultures. Immunofluorescence confocal microscopy revealed that the VSV glycoprotein (VSV G) was targeted to the culture medium–facing surface. In endosteal osteoblasts, VSV G protein was found in the surface facing bone marrow and circulation. On the contrary, Influenza virus hemagglutinin (HA) was localized to the bone substrate-facing surface of the UMR-108 cells. Electron microscopy showed that in the cases where the cells were growing as a single layer, VSV particles were budding from the culture medium–facing surface, whereas Influenza viruses budded from the bone substrate–facing surface. When the cells overlapped, this polarity was lost. Cell surface biotinylation revealed that 55% of VSV G protein was biotinylated, whereas Influenza virus HA was only 22% biotinylated. These findings suggest that osteoblasts are polarized at some point of their life cycle. The bone-attaching plasma membrane of osteoblasts is apical, and the circulation or bone marrow–facing plasma membrane is basolateral in nature.
Urinary Galactosyl-Hydroxylysine in Postmenopausal Osteoporotic Women: A Potential Marker of Bone Fragility
Authors: Cascio Vincenzo Lo , Bertoldo Francesco , Gambaro Greta , Gasperi Elisabetta , Furlan Federico , Colapietro Francesca , Cascio Claudia Lo , Campagnola Mario 
Published: April 2006

Abstract
Alterations of the collagen matrix, e.g., increased hydroxylation and glycosylation of lysyl residues in collagen I, were found in human osteoporotic bone, and it was suggested that they could alter the mechanical properties of skeleton. To test this hypothesis, we evaluated the content of galactosyl-hydroxylysine (GHYL) in bone collagen, as assessed by its urinary excretion, and related it to the occurrence of fracture. Two hundred and fifteen unselected postmenopausal women with osteoporosis were divided in two subgroups (comparable for age, age of menopause, bone mineral density, and biochemical parameters of bone turnover) on the basis of the history of fragility fracture; 115 patients had suffered no fracture and 100 patients had suffered one or more fractures 3 or more years before. Four urinary markers of bone turnover (hydroxyproline, cross-linked N-telopeptide, free deoxypyridoline, and GHYL) were evaluated in all patients. There was no difference between the two groups with regard to all the parameters studied except for GHYL, which was significantly higher in the group with a history of fracture (1.35 ± 0.82 mmol/mol of creatinine [Cr] versus 1.03 ± &lt;0.48 mmol/mol Cr, p &lt; 0.001); this marker did not correlate with other markers of bone remodeling in the fracture group, indicating a possible defect in bone collagen. In conclusion, provided that increased levels of urinary GHYL do reflect overglycosylation of hydroxylysine in bone collagen, the GHYL may be considered a marker of bone collagen quality. Our results, showing higher urinary GHYL in osteoporosis patients with fracture, seem to confirm this suggestion.
Biological Properties of Salmon Calcitonin IV
Authors: Schecroun Nadia , Pidoux Elisabeth , Horne William C. , Hernandez-Lagunas Laura , Baron Roland , Dr. Cressent Michele 
Published: April 2006

Abstract
In this study we characterized the biological activity of the recently identified salmon calcitonin (sCT) IV, in order to evaluate its potential therapeutic value. In the rat bioassay, sCT IV exhibited a 30% higher hypocalcemic activity than sCT I. The capacity of the molecule to inhibit bone resorption was assessed in vitro by the bone resorbing assay and the pit assay. An inhibitory effect, similar to that of sCT I, was observed in both assays. The interaction of sCT IV with the rabbit CT receptor was also studied. The affinity of sCT IV for the receptor was similar to that of sCT I, as was the potency for stimulating cAMP production. The antigenicity of the two molecules was not identical. Thus, this new CT could represent a useful novel therapeutic agent for the treatment of bone disorders.
Cardiac L-Type Calcium Channel α1-Subunit Is Increased by Cyclic Adenosine Monophosphate: Messenger RNA and Protein Expression in Intact Bone
Authors: Wang Xi-Tao , Nagaba Shizuka , Nagaba Yasushi , Leung Steven W. , Wang Jinsong , Qiu Weiping , Zhao Pei-Lin , Guggino Sandra E. 
Published: April 2006

Abstract
L-type calcium channels have been identified previously in both osteoblast-like osteosarcoma cell lines and primary cultures of osteoblasts using numerous techniques such as patch clamp recording, drug inhibited45Ca2+ uptake, and Fura-2 measurements, but intact bone has not been investigated. Using reverse-transcription polymerase chain reaction (RT-PCR) we found that the three major isoforms of the α1-subunit of L-type calcium channels, (α1C, α1D, and α1S) are present in RNA extracted from ROS 17/2.8 osteosarcoma cells, rat femur, and rat skull. Sequencing of most of the α1C-subunit from rat femur and ROS cells revealed that the splice variants in osteosarcoma cells and intact bone differ, but there are no unique sequence variations compared with those found in other tissues. Northern blot analysis of ROS cell RNA indicated that cyclic adenosine monophosphate (cAMP), but not 1α,25-dihydroxyvitamin D3, increased the messenger RNA (mRNA) of the α1C-subunit. Western blot of ROS cell lysates revealed a band of more then 220 kDa, the amount of which increased in cells treated with cAMP. Using confocal microscopy combined with immunohistochemistry in ROS cells, intact bone, and cartilage, we found that the α1C-subunit of this channel is expressed in osteoblasts and chondrocytes suggesting this channel may be a pathway for signal transduction in intact tissue, because it is in osteosarcoma cell lines and primary osteoblasts grown in tissue culture.
Structure, Composition, and Maturation of Newly Deposited Calcium-Phosphate Crystals in Chicken Osteoblast Cell Cultures
Authors: Kuhn Liisa T. , Wu Yaotang , Rey Christian , Gerstenfeld Louis C. , Grynpas Marc D. , Ackerman Jerome L. , Kim Hyun-Man , Dr. Glimcher Melvin J. 
Published: April 2006

Abstract
Characterization of the very early calcium phosphate (CaP) crystals deposited in bone or in osteoblast cell cultures has been hampered by the overwhelming presence of organic matrix components and cells that obscure spectral analyses. We have overcome this problem using isolated protein-free crystals and have obtained new data including31P nuclear magnetic resonance (NMR) spectra for the first time from mineral crystals deposited during osteoblast calcification in culture. Crystals were isolated from cultures at two time points: (a) at first calcium accumulation (day 8–10) and (b) after 60 days of culture, to assess maturational changes. The analyses show that the chemical composition overall and short range order of the early and mature crystals are characteristic of the apatite crystals found in young embryonic chick bone in vivo. No mineral phase other than apatite was detected by any of the methods used.31P NMR spectroscopy identified the HPO4 groups as those present in bone apatite. Similar to bone apatites, no OH groups were detected by Fourier transform infrared (FTIR) spectroscopy. The temporal maturational changes in composition and structure of the mineral phase were difficult to assess because of the continuous deposition of crystals throughout culturing. The pathway of the maturational changes observed were similar to those occurring in chick bone in vivo and synthetic apatite crystals in vitro although to a much smaller extent.
Spaceflight Inhibits Bone Formation Independent of Corticosteroid Status in Growing Rats
Authors: Zerath Erik , Holy Xavier , Roberts Sydney G. , Andre Catherine , Renault Sylvie , Hott Monique , Marie Pierre J. 
Published: April 2006

Abstract
Bone formation and structure have been shown repeatedly to be altered after spaceflight. However, it is not known whether these changes are related to a stress-related altered status of the corticosteroid axis. We investigated the role of corticosteroids on spaceflight-induced effects in rat pelvis and thoracic vertebrae. Thirty-six male Sprague-Dawley rats were assigned to a flight, flight control, or vivarium group (n = 12/group). Bilateral adrenalectomy was performed in six rats per group, the additional six rats undergoing sham surgery. Adrenalectomized (ADX) rats were implanted with corticosteroid pellets. On recovery from spaceflight, thoracic vertebrae and the whole pelvis were removed and processed for biochemistry, histomorphometry, or bone cell culture studies. The 17-day spaceflight resulted in decreased bone volume (BV) in the cotyle area of pelvic bones (−12%; p &lt; 0.05) associated with ∼50% inhibition of bone formation in the cancellous area of pelvic metaphyses and in thoracic vertebral bodies. The latter effect was associated with a decreased number of endosteal bone cells isolated from the bone surface (BS) in these samples (−42%; p &lt; 0.05). This also was associated with a decreased number of alkaline phosphatase positive (ALP+) endosteal bone cells at 2 days and 4 days of culture, indicating decreased osteoblast precursor cell recruitment. Maintaining basal serum corticosterone levels in flight-ADX rats did not counteract the impaired bone formation in vertebral or pelvic bones. Moreover, the decreased ex vivo number of total and ALP+ endosteal bone cells induced by spaceflight occurred independent of endogenous corticosteroid hormone levels. These results indicate that the microgravity-induced inhibition of bone formation and resulting decreased trabecular bone mass in specific areas of weight-bearing skeleton in growing rats occur independently of endogenous glucocorticoid secretion.
Parathyroid Hormone Added to Established Hormone Therapy: Effects on Vertebral Fracture and Maintenance of Bone Mass After Parathyroid Hormone Withdrawal
Authors: Cosman F. , Nieves J. , Woelfert L. , Formica C. , Gordon S. , Shen V. , Lindsay R. 
Published: April 2006

Abstract
Our best pharmacologic agents for osteoporosis treatment prevent no more than 40-60% of osteoporotic fractures in patients at highest risk. Thus, there is a need for agents that can further augment bone mass and reduce fracture risk more substantially. To this end, we investigated the utility of parathyroid hormone (PTH) in combination with established hormone-replacement therapy (HRT) in women with osteoporosis. Fifty-two women who had been on HRT for at least 2 years were enrolled in this trial in which 25 were assigned randomly to remain on HRT alone and 27 were assigned to remain on HRT and also receive daily subcutaneous PTH(1-34) 400 U (25 μg) per day for 3 years. Bone mineral density (BMD) measurements at the spine, hip, and total body as well as biochemical determinations of bone turnover and calcium homeostasis were obtained every 6 months. Lateral thoracic and lumbar spine X-rays were obtained at baseline and annually. Subjects also had measurements of bone density and biochemical indices of bone turnover 1 year after discontinuation of PTH, while HRT was continued. In the group receiving HRT alone, bone density and biochemical variables of bone turnover remained stable throughout the 3-year treatment trial and 1-year follow-up. In the PTH + HRT group, biochemical variables of bone formation and resorption peaked at 6 months and subsequently remained elevated until 30 months at which time levels were indistinguishable from baseline. Subjects in the PTH + HRT group increased bone mass by 13.4 ± 1.4% in the spine, 4.4 ± 1.0% in the total hip, and 3.7 ± 1.4% in the total body. Bone density measurements remained stable 1 year after discontinuation of PTH without any significant loss while women continued HRT. Biochemical variables did not change significantly after cessation of PTH through the 1-year follow-up period. PTH + HRT reduced the percent of women who had vertebral fractures from 37.5% to 8.3% (using a 15% height reduction criterion) and from 25% to 0% (using a 20% height reduction criterion) compared with women receiving HRT alone (p &lt; 0.02 for both). We conclude that ongoing HRT maintains almost all of the PTH-induced bone mass increment for 1 year after discontinuation of PTH. Furthermore, PTH in combination with hormone therapy is an effective means of increasing bone mass throughout the skeleton and specifically reducing vertebral fracture occurrence by 75-100%, compared with HRT alone.
Eating Attitudes and Habitual Calcium Intake in Peripubertal Girls Are Associated with Initial Bone Mineral Content and Its Change over 2 Years
Authors: Barr Susan I. , Petit Moira A. , Vigna Yvette M. , Prior Jerilynn C. 
Published: April 2006

Abstract
This 2-year prospective study examined associations among bone mineral acquisition and physical, maturational, and lifestyle variables during the pubertal transition in healthy girls. Forty-five girls, initially 10.5 ± 0.6 years, participated. Body composition and bone mineral content (BMC) at the spine and total body (TB) were assessed at baseline and annually thereafter using dual-energy X-ray absorptiometry (DXA). Nutrient intakes were assessed using 3-day diet records and a calcium food frequency questionnaire (FFQ), physical activity by questionnaire, sexual maturation using Tanner's stages of breast and pubic hair maturation, growth by height and weight, and eating attitudes using the children's Eating Attitudes Test (Children's EAT). Mean children's EAT subscale scores (dieting, oral control [OC], and bulimia) were stable over time. Median split of OC subscale scores was used to form high and low OC groups. Groups had similar body composition, dietary intake, activity, and Tanner stage at baseline and 2 years. Using height, weight, and Tanner breast stage as covariates, girls with low OC scores had greater TB BMC at baseline (1452 ± 221 g vs. 1387 ± 197 g; p = 0.030) and 2 years (2003 ± 323 g vs. 1909 ± 299 g; p = 0.049) and greater lumbar spine (LS) BMC at 2 years (45.2 ± 8.8 g vs. 41.2 ± 9.6 g; p = 0.042). In multiple regression analysis, OC score predicted baseline, 2 years, and 2-year change in TB and spinal BMC, contributing 0.9-7.6% to explained variance. Calcium intake predicted baseline, 2 years, and 2-year change in TB BMC, explaining 1.6-5.3% of variance. We conclude that both OC and habitual calcium intake may influence bone mineral acquisition.
COL1A1 Sp1 Polymorphism Predicts Perimenopausal and Early Postmenopausal Spinal Bone Loss
Authors: Macdonald Helen M. , McGuigan Fiona A. , New Susan A. , Campbell Marion K. , Golden Michael H. N. , Ralston Stuart H. , Reid David M. 
Published: April 2006

Abstract
Genetic factors play an important role in the pathogenesis of osteoporosis but the genes that determine susceptibility to poor bone health are defined incompletely. Previous work has shown that a polymorphism that affects an Sp1 binding site in the COL1A1 gene is associated with reduced bone mineral density (BMD) and an increased risk of osteoporotic fracture in several populations. Data from cross-sectional studies have indicated that COL1A1 Sp1 alleles also may be associated with increased rates of bone loss with age, but longitudinal studies, which have examined bone loss in relation to COL1A1&gt; genotype, have yielded conflicting results. In this study, we examined the relationship between COL1A1 Sp1 alleles and early postmenopausal bone loss measured by dual-energy X-ray absorptiometry (DXA) in a population-based cohort of 734 Scottish women who were followed up over a 5- to 7-year period. The distribution of genotypes was as expected in a white population with 484 “SS” homozygotes (65.9%); 225 “Ss” heterozygotes (30.7%), and 25 “ss” homozygotes (3.4%). Women taking hormone-replacement therapy (HRT; n = 239) had considerably reduced rates of bone loss at the spine (−0.40 ± 0.06%/year) and hip (−0.56 ± 0.06%/year) when compared with non-HRT users (n = 352; spine, −1.36 ± 0.06%/year; hip, −1.21 ± 0.05%/year; p &lt; 0.001 for both sites). There was no significant difference in baseline BMD values at the lumbar spine (LS) or femoral neck (FN) between genotypes or in the rates of bone loss between genotypes in HRT users. However, in non-HRT users (n = 352), we found that ss homozygotes (n = 12) lost significantly more bone at the lumbar site than the other genotype groups in which ss = −2.26 ± 0.31%/year compared with SS = −1.38 ± 0.07%/year and Ss = −1.22 ± 0.10%/year (p = 0.004; analysis of variance [ANOVA]) and a similar trend was observed at the FN in which ss = −1.78 ± 0.19%/year compared with SS = −1.21 ± 0.06%/year and Ss = −1.16 ± 0.08%/year (p = 0.06; ANOVA). The differences in spine BMD loss remained significant after correcting for confounding factors. Stepwise multiple regression analysis showed that COL1A1 genotype independently accounted for a further 3.0% of the variation in spine BMD change after age (4.0%), weight (5.0%), and baseline BMD (2.8%). We conclude that women homozygous for the Sp1 polymorphism are at significantly increased risk of excess rates of bone loss at the spine, but this effect may be nullified by the use of HRT.
Tibolone Exerts Its Protective Effect on Trabecular Bone Loss Through the Estrogen Receptor
Authors: Ederveen A. G. H. , Kloosterboer H. J. 
Published: April 2006

Abstract
Tibolone (Org OD14) has estrogenic, progestogenic, and/or androgenic activity depending on the tissue. In postmenopausal women, tibolone prevents bone loss without stimulating the endometrium. Tibolone is effective in preventing trabecular bone loss from the peripheral and axial skeleton of young and old ovariectomized (OVX) rats by reducing bone turnover, that is, bone resorption, like estrogens. We evaluated the contribution of the various hormonal activities to tibolone's bone-conserving effect. Three-month-old OVX rats received tibolone (125 μg/rat or 500 μg/rat, twice daily), alone or combined with an antiestrogen, antiandrogen, or antiprogestogen, and the effects on trabecular bone mass and bone turnover were evaluated. Sham-operated and control OVX groups were treated with vehicle. The remaining OVX groups received oral doses of tibolone twice daily, alone or with twice daily (a) antiestrogen ICI 164.384, (b) antiandrogen flutamide, or (c) antiprogestogen Org 31710. For comparison, the effects of 17β-estradiol and testosterone were examined also. After 4 weeks, trabecular bone mineral density (BMD) in the distal femur, plasma osteocalcin, and urinary deoxypyridinoline/creatinine ratio (Dpyr/Cr) were measured. Tibolone or 17β-estradiol significantly blocked ovariectomy-induced loss of trabecular BMD and inhibited bone resorption and bone turnover as judged by reduced Dpyr/Cr ratio and osteocalcin, respectively. These effects of both compounds were counteracted by the antiestrogen. This suggests a major involvement of the estrogen receptor in the action of tibolone on bone metabolism. However, the antiandrogen and the antiprogestogen did not counteract the effects of tibolone, excluding a major role of the androgenic and progestogenic activities of tibolone in its action against trabecular bone loss. The results indicate that tibolone acts on bone almost entirely through activation of the estrogen receptor.
Z Score Prediction Model for Assessment of Bone Mineral Content in Pediatric Diseases
Authors: Ellis Kenneth J. , Shypailo Roman J. , Hardin Dana S. , Perez Maria D. , Motil Kathleen J. , Wong William W. , Abrams Steven A. 
Published: April 2006

Abstract
The objective of this study was to develop an anthropometry-based prediction model for the assessment of bone mineral content (BMC) in children. Dual-energy X-ray absorptiometry (DXA) was used to measure whole-body BMC in a heterogeneous cohort of 982 healthy children, aged 5–18 years, from three ethnic groups (407 European- American [EA], 285 black, and 290 Mexican-American [MA]). The best model was based on log transformations of BMC and height, adjusted for age, gender, and ethnicity. The mean ± SD for the measured/predicted ln ratio was 1.000 ± 0.017 for the calibration population. The model was verified in a second independent group of 588 healthy children (measured/predicted ln ratio = 1.000 ± 0.018). For clinical use, the ratio values were converted to a standardized Z score scale. The whole-body BMC status of 106 children with various diseases (42 cystic fibrosis [CF], 29 juvenile dermatomyositis [JDM], 15 liver disease [LD], 6 Rett syndrome [RS], and 14 human immunodeficiency virus [HIV]) was evaluated. Thirty-nine patients had Z scores less than −1.5, which suggest low bone mineral mass. Furthermore, 22 of these patients had severe abnormalities as indicated by Z scores less than −2.5. These preliminary findings indicate that the prediction model should prove useful in determining potential bone mineral deficits in individual pediatric patients.
Effect of High-Impact and Low-Repetition Training on Bones in Ovariectomized Rats
Authors: Honda Akiko , Umemura Yoshihisa , Nagasawa Seigo 
Published: April 2006

Abstract
This study was designed to investigate the effect of high-impact and low-repetition jump training on bones in ovariectomized (OVX) rats. Forty female Wistar rats were sham-operated (sham) or OVX at the age of 11 weeks. The rats were divided randomly into the following four groups: sham-sedentary (SS; n = 10), sham-exercised (SE; n = 10), OVX-sedentary (OS; n = 10), and OVX-exercised (OE; n = 10). The rats started the jump training at the age of 12 weeks. The jump-training protocol was 10 times/day, 5 days/week and the jumping-height was 40 cm. After 8 weeks of training, the mass and breaking force in the tibia and ulna, cross-sectional areas of diaphysis in the tibia, and serum bone turnover markers were measured. The jump training significantly increased the fat-free dry weight, ash weight, and ultimate breaking force in the tibia. The rate of increase in these parameters was similar in both the sham and the OVX groups. On the other hand, in the ulna, there were no significant changes in the ultimate breaking force. The jump training significantly increased the periosteal perimeter and cortical area, although the increase in these parameters in OE compared with OS was lower than that in SE compared with SS. The jump training significantly increased serum osteocalcin in the OVX groups, as well as in the sham groups. These results suggest that high-impact and low-repetition training had beneficial effects on bone formation and bone biomechanical properties in OVX rats, as well as in sham rats.