bluuebunny/crossref_metadata_2025_split huggingface dataset:
Involvement of Different Second Messengers in Parathyroid Hormone– and Interleukin-1–Induced Interleukin-6 and Interleukin-11 Production in Human Bone Marrow Stromal Cells
Authors: Kim Ghi S. , Kim Chul H. , Choi Cheol S. , Park Joong Y. , Lee Ki-Up 
Published: April 2006

Abstract
Previous studies have suggested that increased secretion of bone active cytokines, such as interleukin-6 (IL-6) and interleukin-11 (IL-11), from osteoblasts and stromal cells play a pivotal role in the activation of osteoclasts and the genesis of osteoporosis. Various systemic and local factors can stimulate IL-6/IL-11 production, but the intracellular mechanism for such stimulation is largely unknown. In this study, we characterized the second messenger signaling in parathyroid hormone (PTH)- and IL-1–induced production of IL-6/IL-11 and studied the possible modulating effects of estrogen. rhPTH(1–34) and rhIL-1α dose-dependently stimulated IL-6 and IL-11 production from human bone marrow stromal cells (hBMSCs). Agonists for protein kinase A (PKA) (forskolin), and protein kinase C (PKC) (phorbol 12-myristate 13-acetate; PMA) also stimulated IL-6/IL-11 production. Rp-diastereoisomer of adenosine cyclic 3′,5′-phosphorothioate (Rp-cAMPS) and H-8, inhibitors of PKA, significantly inhibited PTH-stimulated IL-6/IL-11 production, but did not inhibit IL-1–stimulated IL-6/IL-11 production. In contrast, staurosporine and calphostin C, inhibitors of PKC, suppressed IL-1–stimulated, but not PTH-stimulated, IL-6/IL-11 production. Pretreatment of cells with 17β-estradiol (17β-E2) antagonized IL-1–stimulated IL-6 production. However, PTH-stimulated IL-6 production and IL-1– and PTH-stimulated IL-11 production were not affected by 17β-E2. Similarly, 17β-E2 inhibited PMA-stimulated IL-6 production, whereas neither forskolin-stimulated IL-6/IL-11 production nor PMA-stimulated IL-11 production was affected by 17β-E2. These results indicate that different second messengers are involved in PTH- and IL-1–induced IL-6 and IL-11 production by hBMSCs: PTH and IL-1 stimulate IL-6/IL-11 production via a PKA-dependent and PKC-dependent pathway, respectively. Furthermore, our results suggest that regulation of cytokine production by estrogen in hBMSCs is selective; only the IL-1–induced IL-6 production, which is mediated by PKC pathway, is inhibited, but PTH-induced IL-6 production and PTH/IL-1–induced IL-11 production are not inhibited by estrogen.
Association Between Intestinal Vitamin D Receptor, Calcium Absorption, and Serum 1,25 Dihydroxyvitamin D in Normal Young and Elderly Women
Authors: Kinyamu H. Karimi , Gallagher J. Christopher , Prahl Jean M. , Deluca Hector F. , Petranick Kimberly M. , Lanspa Stephen J. 
Published: April 2006

Abstract
The exact mechanism for the decrease in intestinal calcium absorption with age is not yet understood. A decrease with age in serum 1,25-dihydroxyvitamin D (1,25(OH)2D) or a decrease in the intestinal vitamin D receptor (VDR) protein concentration are possible causes. The objective of this study was to examine the effect of age on these factors. Fifty-nine young women age 25–35 years were compared with 41 elderly women age 65–83 years who underwent measurements of VDR, calcium absorption using a 20 mg and 100 mg calcium carrier, and calciotropic hormones. Calcium absorption by both tests was lower in the elderly women compared with the young women (p &lt; 0.05). Serum 1,25(OH)2D and duodenal VDR protein concentration were not significantly different between the two age groups. Serum 1,25(OH)2D correlated with the 20 mg calcium absorption test in both young (r = 0.35, p &lt; 0.007) and elderly women (r = 0.58, p &lt; 0.0001) and with the 100 mg calcium absorption in the elderly (r = 0.32; p &lt; 0.05). VDR did not correlate with calcium absorption in young women or elderly women, nor did VDR correlate with serum 1,25(OH)2D and serum 25-hydroxyvitamin D. In summary, the decrease in calcium absorption cannot be explained by a decrease in intestinal VDR. The correlation between serum 1,25(OH)2D and both calcium absorption tests only accounts for 12–30% of the variance in the age-related change in the calcium absorption tests. Other factors, not yet understood, are responsible for the decline in calcium absorption with age.
Calcaneal Bone Mineral Density Predicts Fracture Occurrence: A Five-Year Follow-up Study in Elderly People
Authors: Cheng Sulin , Suominen Harri , Sakari-Rantala Ritva , Laukkanen Pia , Avikainen Veikko , Heikkinen Eino 
Published: April 2006

Abstract
A 5-year follow-up study investigated calcaneal bone mineral density (BMD) and changes in BMD in relation to fracture occurrence. The subjects comprised two cohorts born in 1914 and 1910 living in the city of Jyväskylä in central Finland. One hundred and three men (82%) and 188 women (73%), aged 75, and 57 men (74%) and 136 women (65%), aged 80, of the eligible population participated in the baseline bone measurements. The follow-up bone measurements were obtained for 59 men (68%) and 119 women (66%), aged 80 years, and for 21 men (53%) and 61 women (48%), aged 85 years. During the follow-up period, 8 men and 36 women from the younger and 11 men and 24 women from the older cohort sustained at least one fracture. When the baseline levels of BMD were related to fracture occurrence, the results clearly showed that with increased BMD values the probability of fracture decreased. Where men and women had similar BMD values, they also had a similar fracture probability. Except for one woman in the older cohort, none of those who had initial BMD values more than 1 standard deviation above the mean for their age developed a fracture during the follow-up period. The mean annual decrease in BMD was greater in the women (2.5–2.7%) than in the men (0.8–1.0%). The BMD change tended to associate with fracture occurrence only in the 75-year-old women (p = 0.075). The results suggest that calcaneus BMD can be used as a predictor of fracture occurrence in 75− to 80-year-old men and women. However, associating fractures with the change in BMD was difficult due to the limited number of survivors and initial differences in BMD values.
Down-Regulation of Gap Junctional Intercellular Communication Between Osteoblastic MC3T3-E1 Cells by Basic Fibroblast Growth Factor and a Phorbol Ester (12-O-Tetradecanoylphorbol-13-Acetate)
Authors: Shiokawa-Sawada Miho , Mano Hiroshi , Hanada Kooji , Kakudo Shinji , Kameda Takashi , Miyazawa Koshi , Nakamaru Yukiya , Yuasa Tatsuhisa , Mori Yoshihisa , Kumegawa Masayoshi , Hakeda Yoshiyuki 
Published: April 2006

Abstract
To address the relation between osteoblast growth and cell-to-cell communication, we examined the effects of basic fibroblast growth factor (bFGF) and 12-O-tetradecanoylphorbol-13-acetate (TPA), both potent stimulators of osteoblastic proliferation, on gap junctional intercellular communication between osteoblastic MC3T3-E1 cells. The level of intercellular communication was estimated by a photobleaching method. TPA inhibited the degree of intercellular communication in two different time-dependent manners. The early (&lt;1 h) inhibition by TPA was consistent with an increase in the phosphorylation of connexin 43 (Cx43). The later inhibition was caused by reduction in the total amount of Cx43 on the plasma membrane, due to the decrease in the level of Cx43 transcripts. These qualitative and quantitative modulations by TPA were inhibited by a selective inhibitor of protein kinase C, GF109203X. bFGF also attenuated the gap junctional intercellular communication. However, short exposure (&lt;5 h) to bFGF did not affect the communication. The fact that the growth factor immediately stimulated the phosphorylation of Cx43 indicates that the phosphorylation site(s) affected by bFGF was not involved in the inhibition of communication. The decrease in the intercellular communication level was detected by the longer exposure (&gt;8 h) to bFGF and paralleled the decline in the Cx-mRNA level. This inhibitory effect of bFGF was abolished by the addition of a tyrosine kinase inhibitor, herbimycin A. Thus, gap junctional intercellular communication between osteoblasts was down-regulated by osteoblastic mitogens through different mechanisms of the modulation of Cx43.
The Effect of Vitamin D Supplementation on the Bone Mineral Density of the Femoral Neck Is Associated with Vitamin D Receptor Genotype
Authors: Graafmans W. C. , Lips P. , Ooms M. E. , Van Leeuwen J. P. T. M. , Pols H. A. P. , Uitterlinden A. G. 
Published: April 2006

Abstract
Recent studies suggest that variations of the vitamin D receptor (VDR) gene are related to bone mineral density (BMD). In this study, we examined the effect of vitamin D3 supplementation on BMD at the femoral neck in relation to VDR genotype. We analyzed 81 women, age 70 years and over, who participated in a placebo-controlled clinical trial on the effect of vitamin D3 supplementation (400 IU daily for at least 2 years) on BMD and fracture incidence. VDR genotype was based on the presence (b) or absence (B) of the BsmI restriction site. Mean BMD of the right and left femoral neck was measured at baseline and after 1 and 2 years. Dietary calcium, body mass index, and years since menopause were assessed at baseline while biochemical markers were measured at baseline and after 1 year. There was no difference among the BB, Bb, and bb genotype for baseline measurements of BMD at the femoral neck (mean and SD, g/cm2: 0.70 (0.10), 0.71 (0.12), and 0.69 (0.10), respectively), nor for any of the biochemical indices. The mean increase of BMD in the vitamin D group relative to the placebo group, expressed as percentage of baseline BMD, was significantly higher (p = 0.03) in the BB (ΔBMD: 4.4%, p = 0.04) and Bb genotype (ΔBMD: 4.2%, p = 0.007) compared with the bb genotype (ΔBMD: −0.3%, p = 0.61). No significant changes were found for any of the other measured parameters. The VDR genotype-dependent effect of vitamin D supplementation in these elderly subjects suggest a functional involvement of VDR gene variants in determining BMD.
Parathyroid Tumor Suppressor on 1p: Analysis of the p18 Cyclin-Dependent Kinase Inhibitor Gene As a Candidate
Authors: Tahara Hideki , Smith Alison P. , Gaz Randall D. , Zariwala Maimoona , Xiong Yue , Arnold Andrew 
Published: April 2006

Abstract
Loss of chromosome arm 1p DNA is the most common molecular defect thus far observed in human parathyroid adenomas, suggesting that 1p is the location of a putative tumor suppressor gene (or genes) whose inactivation contributes frequently to parathyroid tumorigenesis. To narrow the genomic location of this tumor suppressor gene, we analyzed 25 sporadic parathyroid adenomas for allelic loss of polymorphic DNA loci on chromosome 1 using 11 microsatellite markers not previously scored for this set of tumors. Allelic loss on chromosome arm 1p DNA was observed in 8 of 25 adenomas. Marker deletion patterns showed some complexity, with the regions most commonly deleted in these tumors being 1p36 and 1p35–p31. The 1p35–p31 region contains an excellent candidate tumor suppressor gene, p18, whose product is a cell cycle regulator that inhibits the cyclin D1-associated kinase CDK6. Given that cyclin D1 is a parathyroid oncogene, inactivation of an inhibitor of cyclin D1 function, like p18, might also cause excessive parathyroid growth. To examine the involvement of p18 in parathyroid tumorigenesis, we analyzed 25 parathyroid adenomas for mutations of the p18 coding exons by single strand conformational polymorphism analysis and sequencing. No point mutations were found in any of the 25 adenomas. These observations indicate that inactivating mutation of the p18 gene occurs uncommonly, if at all, in parathyroid adenomas. In addition, the data raise the important possibility that more than a single tumor suppressor gene on 1p could contribute to parathyroid neoplasia.
Enhancement by Sex Hormones of the Osteoregulatory Effects of Mechanical Loading and Prostaglandins in Explants of Rat Ulnae
Authors: Cheng Ming Zhao , Zaman Gul , Rawlinson Simon C. F. , Pitsillides Andrew A. , Suswillo Rosemary F. L. , Lanyon Lance E. 
Published: April 2006

Abstract
Explants of ulnae from 5-week-old male and female rats were cleaned of marrow and soft tissue and, in the presence and absence of 10−8 M 17β-estradiol (E2) or 5α-dihydrotestosterone (DHT), mechanically loaded or treated with exogenous prostanoids previously shown to be produced during loading. Over an 18-h period, mechanical loading (peak strain 1300 μϵ, 1 Hz, 8 minutes, maximum strain rate 25,000 μϵ/s), prostaglandin E2 (PGE2) and prostacyclin (PGI2) (10−6 M), each separately produced quantitatively similar increases in cell proliferation and matrix production in bones from males and females, as indicated by incorporation of [3H]thymidine into DNA and [3H]proline into collagen. E2 and DHT both increased [3H]thymidine and [3H]proline incorporations, E2 producing greater increases in females than in males. Indomethacin abrogated the effects of loading, but had no effects on those of sex hormones. Loading, or prostanoids, together with sex hormones, produced responses generally equal to or greater than the addition of the individual influences acting independently. In females there was a synergistic response in [3H]thymidine incorporation between loading and E2, which was quantitatively similar to the interaction between E2 and PGE2 or PGI2. The interaction between loading and E2 for [3H]proline incorporation was not mimicked by these prostanoids. In males the synergism in [3H]proline incorporation seen between loading and DHT was mimicked by that between PGI2 and DHT. We conclude that loading stimulates increased bone cell proliferation and matrix production in situ through a prostanoid-dependent mechanism. This response is equal in size in males and females. Estrogen and testosterone increase proliferation and matrix production through a mechanism independent of prostanoid production. The interactions between loading and hormones are reproduced in some but not all cases by E2 and prostaglandins. E2 with loading and prostaglandins has greater effects in female bones, while DHT with loading and prostaglandins has greater effects in males.
Prospective Ten-Month Exercise Intervention in Premenarcheal Girls: Positive Effects on Bone and Lean Mass
Authors: Morris Fiona L. , Naughton Geraldine A. , Gibbs Joanne L. , Carlson John S. , Wark John D. 
Published: April 2006

Abstract
Enhancement of bone mineral acquisition during growth may be a useful preventive strategy against osteoporosis. The aim of this study was to explore the lean mass, strength, and bone mineral response to a 10-month, high-impact, strength-building exercise program in 71 premenarcheal girls, aged 9–10 years. Lean body mass, total body (TB), lumbar spine (LS), proximal femur (PF), and femoral neck (FN) bone mineral were measured using the Hologic QDR 2000+ bone densitometer. Strength was assessed using a grip dynamometer and the Cybex isokinetic dynamometer (Cybex II). At baseline, no significant difference in body composition, pubertal development, calcium intake, physical activity, strength, or bone mineral existed between groups. At completion, there were again no differences in height, total body mass, pubertal development, calcium intake, or external physical activity. In contrast, the exercise group gained significantly more lean mass, less body fat content, greater shoulder, knee and grip strength, and greater TB, LS, PF, and FN BMD (exercise: TB 3.5%, LS 4.8%, PF 4.5%, and FN 12.0%) compared with the controls (controls: TB 1.2%, LS 1.2%, PF 1.3%, and FN 1.7%). TB bone mineral content (BMC), LS BMC, PF BMC, FN BMC, LS bone mineral apparent density (BMAD), and FN bone area also increased at a significantly greater rate in the exercise group compared with the controls. In multiple regression analysis, change in lean mass was the primary determinant of TB, FN, PF, and LS BMD accrual. Although a large proportion of bone mineral accrual in the premenarcheal skeleton was related to growth, an osteogenic effect was associated with exercise. These results suggest that high-impact, strength building exercise is beneficial for premenarcheal strength, lean mass gains, and bone mineral acquisition.
Five Jumps per Day Increase Bone Mass and Breaking Force in Rats
Authors: Umemura Yoshihisa , Ishiko Toshihiro , Yamauchi Takeshi , Kurono Masashi , Mashiko Shoji 
Published: April 2006

Abstract
The effects of jump training on bone morphological and mechanical properties were investigated in immature bones of female Fischer 344 rats. Five-week-old rats were divided into control or five jump-trained groups comprised of 5-, 10-, 20-, 40-, and 100-jump groups, representing the number of jumps per day. The rats were jump-trained 5 days/week for 8 weeks, and the height of jump was increased to 40 cm progressively. The femur and tibia in the 5-jump group had significantly greater fat-free dry weights per body weight and maximum loads at the fracture tests than those in the control group. The tibia in the 5-jump group also had significantly larger cortical area at the cross-sectional analysis. Although a slight tendency toward increase according to the number of jumps per day was observed, there were few differences in bone morphological and mechanical parameters among the 10-, 20-, and 40-jump groups. The present results indicate that a large number of strains per day is not necessary for bone hypertrophy to develop in rats.
The Relationship Between Magnesium and Calcium Kinetics in 9- to 14-Year-Old Children
Authors: Abrams Steven A. 
Published: April 2006

Abstract
Few measurements of magnesium (Mg) kinetics have been performed, especially in children and adolescents. Simultaneous Mg and calcium (Ca) kinetics following intravenous administration of42Ca and25Mg were measured in 22 children (10 boys and 12 girls) 9–14 years of age. Kinetic values, including the body pool masses (MgComp and CaComp for the Mg and Ca compartment masses, respectively) and bone/tissue (hard and soft tissue) Ca and Mg deposition rates (Vo+Ca and Vo+Mg, respectively) were calculated using the Simulation, Analysis, and Modeling (SAAM) program. No significant differences were found between males and females (p &gt; 0.3 for each comparison) for pool masses or deposition rates. Vo+Ca and Vo+Mg were highly correlated (r = 0.78, p &lt; 0.001). Vo+Mg, but not Vo+Ca, was closely correlated with body weight (r = 0.55, p &lt; 0.01 and r = 0.16, p = 0.47, respectively). Similarly, MgComp was more closely correlated with body weight (r = 0.76, p &lt; 0.01) than CaComp (r = 0.37, p = 0.10). Neither Vo+Ca nor CaComp increased significantly over the age range studied. However, Vo+Mg and MgComp were significantly positively correlated with age. These findings demonstrate differences in regulation of Ca versus Mg kinetics by young adolescents. These differences may be related to the greater utilization of Mg for muscle and soft tissue growth. The close relationship between Vo+Mg and body weight suggests that the current practice of relating Mg intake requirements to body weight, as well as age, is appropriate for young adolescents.
A Longitudinal Study of Bone Gain in Pubertal Girls: Anthropometric and Biochemical Correlates
Authors: Cadogan Joanna , Blumsohn Aubrey , Barker Margo E. , Eastell Richard 
Published: April 2006

Abstract
The aim of this longitudinal study was to investigate the factors associated with bone mineral acquisition in pubertal girls. Subjects were 37 healthy, Caucasian girls aged 12.1 years (SD 0.3). Measurements were made at 6-month intervals over a period of 18 months and included total body bone mineral content (TBBMC), total body bone mineral density (TBBMD), lean mass, and fat mass by dual-energy X-ray absorptiometry, anthropometry, lifestyle factors, four biochemical markers of bone turnover, hormonal status, and fractional calcium absorption. In multiple regression analysis, correlates of relative gain in TBBMC were gain in lean mass (p &lt; 0.001) and estradiol (p = 0.008). For TBBMD, correlates were gain in lean (p &lt; 0.001) and fat mass (p = 0.003), estradiol (p &lt; 0.001), dietary energy intake (p = 0.003), and parathyroid hormone (p = 0.023). Statural growth and gain in bone mass were unrelated; both height velocity and bone turnover peaked ∼20 months prior to menarche, whereas gain in bone mass peaked at menarche. Bone turnover markers correlated with height velocity (0.40 &lt; r &lt; 0.62), but not with bone gain. Estradiol was independently and negatively associated with all markers of bone turnover (−0.67 &lt; r &lt; −0.80). We conclude that estradiol is an important determinant of bone mineral gain in pubertal girls and is probably responsible for the reduction in bone turnover in late puberty; lean mass was the body composition parameter most closely associated with bone gain; height gain and bone gain are dissociated during the period of rapid growth at puberty; and bone turnover markers are modestly related to height gain, but are not predictive of bone gain.
Bone Mineral and Body Composition Measurements: Cross-Calibration of Pencil-Beam and Fan-Beam Dual-Energy X-Ray Absorptiometers
Authors: Ellis Kenneth J. , Shypailo Roman J. 
Published: April 2006

Abstract
Pencil-beam dual-energy X-ray absorptiometers (DXA) are being replaced with instruments that rely solely on fan-beam technology. However, information has been lacking regarding the translation of bone mineral and body composition data between the two devices. We have compared total body scans using pencil-beam (Hologic QDR-2000W) and fan-beam (Hologic QDR-4500A) instruments for 33 children (ages 3–18 years) and 14 adults. Bone mineral content (BMC), bone mineral density (BMD), fat, lean, and body fatness (%fat) values were highly correlated (r2 = 0.984–0.998) between the two DXA instruments. The mean differences between the paired measurements were: ΔBMC = 7.5 ± 73.6 g, ΔBMD = 0.0074 ± 0.0252 g/cm2, Δlean = 1.05 ± 1.8 kg, Δfat = −0.77 ± 1.7 kg, and Δ%fat = −0.94% ± 2.5%. The BMC and BMD values were not statistically different, whereas the differences for the body composition values were significant (p &lt; 0.02–0.005). Regression equations are provided for conversion of bone and body composition data between pencil-beam and fan-beam values for the whole body. To test the performance of these equations for a second group (23 subjects), predicted values were compared with the measured data obtained using the fan-beam instrument. The mean differences were −1.0% to 1.4%, except for body fat mass, where the difference was 6.4%. For cross-sectional studies, the two DXA technologies can be considered equivalent after using the translational equations provided. For longitudinal studies in which small changes in body composition for the individual are to be detected, we recommend that the same DXA instrument be used whenever possible. For example, transition from a pencil-beam to a fan-beam instrument could, in extreme cases, result in differences as large as 19% for the estimate of body fat mass.