bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ascorbate uptake by ROS 17/2.8 osteoblast-like cells: Substrate specificity and sensitivity to transport inhibitors
Authors: Dr. Dixon S. Jeffrey , Kulaga Andrew , Jaworski Ewa M. , Wilson John X. 
Published: February 2010

Abstract
Ascorbate (reduced vitamin C) is required for bone formation. We have shown previously that both the osteoblast-like cell line ROS 17/2.8 and primary cultures of rat calvarial cells possess a saturable, Na+-dependent uptake system for L-ascorbate (J Membr Biol 111:83–91, 1989). The purpose of the present study was to investigate the specificity of this transport system for organic anions and its sensitivity to transport inhibitors. Initial rates of ascorbate uptake were measured by incubating ROS 17/2.8 cells with [L-14C]ascorbate at 37°C. Uptake of [L-14C]ascorbate (5 μM) was inhibited 98 ± 1% by coincubation with unlabeled L-ascorbate (3 mM) and 48 ± 4% by salicylate (3 mM), but it was not affected by 3 mM formate, lactate, pyruvate, gluconate, oxalate, malonate, or succinate. Uptake of the radiolabeled vitamin also was not affected by acute (1 minute) exposure of the cells to the Na+ transport inhibitors amiloride and ouabain or the glucose transport inhibitor cytochalasin B. In contrast, anion transport inhibitors rapidly (&lt; 1 minute) and reversibly blocked [L-14C]ascorbate uptake. In order of potency, these drugs were 4,4′-diisothiocyanostilbene-2,2′-disulfonic acid (DIDS) = sulfinpyrazone &gt; furosemide = 4-acetamido-4′-isothiocyanostilbene-2,2′-disulfonic acid (SITS). These findings indicate that the ascorbate transporter is relatively specific for the ascorbate anion, since other organic anions (with the exception of salicylate) did not compete with ascorbate for uptake. Rapid and reversible inhibition by the impermeant antagonists DIDS and SITS suggests that they interact directly with the ascorbate transporter, consistent with location of the transport system in the plasma membrane.
Correlates of cortical bone mass among premenopausal and postmenopausal japanese women
Authors: Lacey Janet M. , Anderson John J.B. , Fujita Takuo , Yoshimoto Yoshio , Fukase Masaaki , Tsuchie Setsuko , Koch Gary G. 
Published: February 2010

Abstract
Few studies have examined the multifactorial risk factors of bone mass in Asian populations. This cross-sectional study was designed to explore relationships between bone mass and environmental variables, including dietary and life-style factors, in Japanese women living in Japan. A total of 178 Japanese women completed the study: 89 premenopausal, ages 35–40, and 89 postmenopausal, ages 55–60. Midradial bone mineral content (MBMC) and bone mineral content per unit area, referred to as bone density (MBMD), were measured using single-photon absorptiometry. The major results of this investigation were the following: (1) The postmenopausal women differed significantly from the premenopausal women in having lower radial bone parameters, lower mean height, later age of menarche, and higher dietary intakes of carbohydrates, vegetables, and milk with a lower intake of caffeine. (2) Current protein intake was a positive correlate of MBMC in both groups. (3) Intake of vegetables (leafy green, yellow, orange, and white) and current milk intake were positively associated with MBMC in the postmenopausal women. (4) For the premenopausal women, irregular menstrual cycles was a negative correlate of MBMC, and for the postmenopausal women, years of menopause was negatively associated with MBMC and MBMD. Longitudinal studies are needed to establish more conclusively associations among diet, life-style, and reproductive history and bone mass of Japanese women.
Demonstration that bone mass is greater in black than in white children
Authors: Bell Norman H. , Shary Judith , Stevens June , Garza Martha , Gordon Leonie , Edwards Jeanne 
Published: February 2010

Abstract
Osteoporosis and hip fractures are less common and bone mass is greater in black than in white women. To determine if bone mass is greater in black than in white children, bone mineral density (BMD) of the midradius by single-photon absorptiometry and BMD of the lumbar spine (L1-L4), trochanter, and femoral neck by dual-photon absorptiometry were measured in 20 black boys, 18 black girls, 33 white boys, and 35 white girls between the ages of 7 and 12 years. Mean age (10.4 ± 0.3 versus 10.2 ± 0.2 years) and body weight (39 ± 2 versus 38 ± 2 kg) in the blacks and whites, respectively, were not different in the two groups, and the ages and weights of the boys and girls were not different from each other. BMD were significantly greater in black than in white children at each site, in the black than in white boys at the trochanter and femoral neck, and in the black than in white girls at each site. In both races, BMD varied directly with age and body weight. Multivariate analysis showed that BMD were greater at the midradius, lumbar spine, trochanter, and femoral neck in the black than in the white children, that BMD of the lumbar spine was greater in the girls than in the boys, and that BMD of the trochanter and femoral neck were greater in the boys than in the girls. There were significant partial correlations between race and BMD and between BMD and body weight at each site, between sex and BMD at the lumbar spine, trochanter, and femoral neck, and between age and BMD at the midradius, trochanter, and femoral neck. Race, sex, age, and body weight together accounted for 49-66% of the variation in bone mass. Thus, BMD of the midradius, spine, and hip are greater in black than in white children, body weight and age are important determinants of bone mass, and some sex differences in bone mass are present at this age.
Calibration of dual-energy X-ray absorptiometry for bone density
Authors: Mazess Richard B. , Trempe Joel A. , Bisek Joseph P. , Hanson James A. , Hans Didier 
Published: February 2010

Abstract
Bone Mineral Content (Bmc, G) Using Dexa (Lunar Dpx) Was Measured On Known Hydroxyapatite Samples In A Water Bath In The Presence Of Uniform And Nonuniform Coverings Of Fat-Equivalent Materials. Selective Placement Of Paraffin Over Bone Had A Greater Effect Than Lard In Reducing Apparent Bmc, And Polycarbonate Plastic Had A Lesser Effect. Measured Bmc Was 100.1 ± 1.1% Of Actual Hydroxyapatite Weight When (1) Fat Over Bone Was About Twice The Mass Of Hydroxyapatite, And (2) The Surrounding Soft Tissue Was 15–30% Fat. There Was A Linear Relationship Between Observed And Expected Bmc, Area (Cm2), and bone mineral density (BMD, g/cm2) measured on an aluminum phantom using either the Lunar DPX or the Hologic QDR-1000. The measured area with the two densitometers was identical, but BMC differed. For both an anthropomorphic phantom and human subjects, use of a constant-threshold (0.2 g/cm2) edge-detection algorithm excluded less low-density bone from the transverse processes than the standard DPX edge-detection algorithm. Differences in edge detection could influence the results obtained with phantoms and in vivo and make system intercomparison difficult.
Kinetics of the osteoclast cytoskeleton during the resorption cycle in vitro
Authors: Lakkakorpi Paivi T. , Väänänen Kalervo H. 
Published: February 2010

Abstract
Resorption and migration phases alternate in the life of the osteoclast. We have previously described a specific microfilament structure at the attachment sites in resorbing osteoclasts. In the present study we have examined microfilaments and microtubules in both resorbing and migrating rat osteoclasts cultured on bone slices. In migrating osteoclasts microfilaments form so-called podosome structures containing vinculin, talin, and F-actin at the paramarginal area of the cell. When the osteoclast prepares itself for resorption, the podosomes gather to a certain area and form a broad ring around the area, which is then resorbed. In the resorbing osteoclast, vinculin and talin form a continuous double circle, which may be partially formed by podosomes, and between these double circles a broad zone is formed by F-actin. Narrow vinculin and Factin rings were found in osteoclasts at the end of the resorption phase. The different configurations of microfilaments in 1 and 2 day cultures were correlated in terms of their relationship to the resorption lacunae. The vitamin A derivative isotretinoin significantly stimulated resorption and increased the number of microfilament configurations associated with the resorption pits. On the other hand, Bt2cAMP abolished resorption and prevented the formation of a specific ring structure of microfilaments. Based on these data, a kinetic model of the whole migration-resorption cycle of the osteoclast cultured on the bone slice is presented. With α-tubulin stainings of microtubules two different cytoskeletal organizations were observed. In migrating osteoclasts, microtubules were evenly distributed over the whole cell. In the resorbing osteoclast, there was a noticeable concentration of these cytoskeletal structures at cytoplasmic sites closest to the resorption lacuna. This orientation of microtubules may reflect the active secretory function of the resorbing osteoclast.
Clodronate inhibits contraction and prevents the action of L-type calcium channel antagonists in vascular smooth muscle
Authors: Paspaliaris Vasilis , Leaver David D. 
Published: February 2010

AbstractClodronate (dichloromethylenebisphosphonate) decreased vasoconstriction of the isolated perfused rat tail artery mediated by norepinephrine and by Ca2+ in a K+-depolarizing solution. The norepinephrine contractile response was divided into two components by sequential manipulation of the composition of the perfusion fluid, where the first component is due to the release of Ca2+ from intracellular stores and the second to the influx of Ca2+ from extracellular fluid. Clodronate (20 μM) decreased only the first component of the response at a norepinephrine concentration of 50 nM, and both components of the response at a higher norepinephrine concentration (100 nM). The L-type Ca2+ channel blocking drugs, nicardipine (10 nM) and verapamil (1 μM), reduced the second component of the norepinephrine-mediated vasoconstriction, but in the presence of clodronate (20 μM) this blocking action was prevented. These results were confirmed by examining the interaction between clodronate and nicardipine on norepinephrine and K+-mediated lanthanum (La3+)-resistant unidirectional 45Ca uptake. Nicardipine (1–10 nM) decreased the norepinephrine (100 nM) and K+-induced (60 mM) La3+-resistant unidirection 45Ca uptake in a concentration-dependent manner, but in the presence of clodronate (20 μM) this concentration-dependent response was abolished. Thus, clodronate not only reduced agonist-induced Ca2+ release from intracellular stores and Ca2+ influx through L-type Ca2+ channels but also prevented L-type Ca2+ channel antagonists from exerting their effect. These results indicate clodronate has two sites of action during vascular smooth muscle contraction: the first on intracellular mobilization of Ca2+ and the second on L-type Ca2+ channels.
Interleukin-1α stimulates the release of prostaglandin E2 and phospholipase A2 from fetal rat calvarial cells in vitro: Relationship to bone nodule formation
Authors: Ellies Lesley G. , Heersche Johan N.M. , Vadas Peter , Pruzanski Waldemar , Stefanski Eva , Aubin Jane E. 
Published: February 2010

Abstract
We have shown previously that interleukin-1 (IL-1) has biphasic effects on the formation of bone nodules in long-term cultures of fetal rat calvarial (RC) cells (Ellies and Aubin, Cytokine 2:430–437, 1990). To determine the role of arachidonic acid metabolism in this process, we have examined the release of prostaglandin E2 (PGE2) and phospholipase A2 (PLA2) from RC cells under conditions that allowed concomitant analysis of the formation of bone nodules. Recombinant human IL-1α (rhIL-1α) stimulated PGE2 and PLA2 release in a time- and dose-dependent manner. PGE2 release was highest in preconfluent cultures (days 1–6) and was stimulated up to 8.5-fold in response to 50 U/ml of rhIL-1α. In contrast, extracellular PLA2 activity was maximal in postconfluent cultures, with 50 U/ml of rhIL-1α causing a 20-fold increase by day 15. PLA2 release by RC cells was not significantly affected by PGE2, the glucocorticoid dexamethasone, or the cyclooxygenase inhibitor indomethacin. Indomethacin partially blocked the inhibition of bone nodule formation caused by rhIL-1α, and exogenous PGE2 reversed this effect. Addition of group I PLA2 from Naja naja venom to RC cells had no effect on bone nodule development; however, group II PLA2 from Crotalus adamanteus venom inhibited the formation of bone nodules in a dose range similar to that induced by rhIL-1α. These results indicate that PGE2 release does not have a direct temporal correlation with increases in PLA2 activity. In addition, the data show that only part of the inhibition of bone formation seen with rhIL-1α is mediated by PGE2 and suggest that extracellular PLA2 also accounts for part of the inhibition.
Binding of insulin-like growth factors to cultured rat calvarial cells with differing biologic responses
Authors: Cantrell Paul R. , Frolik Charles A. , Ellis Lee F. , Dr. Williams Daniel C. 
Published: February 2010

Abstract
The insulin-like growth factors (IGFs) are considered important regulators of bone metabolism affecting a number of biologic responses in vitro. Primary fetal rat calvarial cells (PRC) and a cloned adult rat calvarial cell line (C3) both exhibit a concentration-dependent IGF stimulation of [3H]thymidine incorporation into DNA, but the C3 cells show a greater sensitivity and magnitude of response. IGF-I and IGF-II were nearly equipotent in PRC cultures, but IGF-I was more than twice as active as IGF-II in the C3 cultures. This effect of the IGFs on DNA synthesis in two bone cell cultures with different culture histories has been correlated with receptor and binding protein profiles. Specific high-affinity IGF binding sites were found in both cell types. In general, the sites present on PRC cells showed a preference for binding IGF-II over IGF-I, but C3 cells displayed two types of relatively specific binding sites. In both cell types [125I]IGF-I bound primarily to a protein with IGF type I receptor characteristics. However, in PRC cells, [125I]IGF-II cross-linked specifically with proteins that had IGF type II receptor characteristics plus several sites unique to these cells; in C3 cells, [125I]IGF-II bound to a 139 kD protein that could be displaced by either IGF-I or IGF-II. Finally, IGF-II-specific 85 and 67 kD proteins were common to both cell types. From these studies, it is apparent that the IGFs bind to a variety of high-affinity binding sites in bone cells and that these sites differ between a highly responsive and a less responsive bone cell population.
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

Abstract
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

Abstract
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

Abstract
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 &gt; 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

Abstract
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

Abstract
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.