bluuebunny/crossref_metadata_2025_split huggingface dataset:
A PCR Analysis of ERα and ERβ mRNA Abundance in Rats and the Effect of Ovariectomy
Authors: Dr. Lim S. K. , Won Y. J. , Lee H. C. , Huh K. B. , Park Y. S. 
Published: April 2006

Abstract
To study the relative abundance and the changes of both estrogen receptor alpha (ERα) and ERβ mRNA before and after ovariectomy in major organs important to the regulation of calcium homeostasis, we compared the degree of mRNA expression of ERα to that of ERβ in rat tissues by performing competitive reverse transcription polymerase chain reaction (RT-PCR) with internal standards. Both ERα and ERβ were highly expressed in the ovary {ERα[(2.2 ± 0.33) × 107 copies/μg of total RNA] &gt; ERβ[(1.2 ± 0.33) × 105 copies/μg of total RNA]} as we expected. The bone marrow and renal cortex were very important target organs of estrogen because ERα was highly expressed ∼2 × 105 copies/μg of total RNA, but marrow cells revealed only a very weak expression of ERβ [(0.7 ± 0.21) × 102 copies/μg of total RNA]. Both ERα and ERβ were expressed in the trabecular bone [(3.2 ± 0.56) × 103 copy/μg of RNA] and [(2.8 ± 0.21) × 102 copy/μg of RNA], respectively. However, they were not detected in the cortical bone. In the jejunum, the expression of ERα was not detectable, while ERβ was expressed very weakly [(1.1 ± 0.24) × 102 copies/μg of total RNA]. The thyroid gland expressed low copy numbers of ERβ [(6.0 ± 0.23) × 102 copies/μg of total RNA], but the parathyroid gland was negative for both ERα and ERβ mRNA. In cultured stromal cells, ERα and ERβ mRNAs were not detected after a 24-h culture; however, the rates of mRNA expression of ERα and ERβ reached ∼105 copies/μg of total RNA and ∼102 copies/μg of total RNA, respectively, after 9-, 11-, and 13-day cultures. After ovariectomy, the expression of ERα mRNA decreased abruptly in the bone marrow and renal cortex, and both ERα and ERβ were barely detected in the trabecular bone. In conclusion, ERα might be the main ER in organs important for calcium homeostasis, except in the jejunum. The mRNA expression of ERα in the bone marrow and renal cortex decreased abruptly after ovariectomy, which may partially explain why the effect of estrogen deficiency can be amplified and why trabecular bone loss is more predominant than cortical bone loss shortly after surgical or natural menopause.
Estrogen Regulation of Intestinal Calcium Absorption in the Intact and Ovariectomized Adult Rat
Authors: ten Bolscher Marieke , Netelenbos J. Coen , Barto Rob , van Buuren Lotti M. , van der vijgh Wim J. F. 
Published: April 2006

Abstract
Studies were carried out to examine the mechanism of action of estrogen on intestinal calcium absorption in the rat. Three-month-old Wistar rats were sham-operated or ovariectomized (OVX). They were fed a diet containing 0.4% Ca, 0.4% P, and 2000 IU vitamin D3/kg. Eight weeks after operation, both OVX and sham-operated rats were randomly assigned to eight treatment groups. Five groups received per 100 g of body weight 12.5 ng calcitriol (1,25-dihydroxyvitamin D3); 7.5 μg of estradiol-benzoate; 7.5 μg of estradiol-benzoate and 0.1 mg of ICI 182780; 12.5 ng of calcitriol and 0.1 mg of ICI 182780; and 0.1 mg of ICI 182780, respectively. Three groups received the various vehicles used. Intestinal calcium absorption was measured in vivo using single pass perfusion of the duodenum. OVX did not change intestinal calcium absorption. A pharmacological dose of estradiol-benzoate caused a significant increase in intestinal absorption of calcium, which was comparable to that of a pharmacological dose of calcitriol in both OVX and sham-operated rats. Estrogen-induced rise in intestinal calcium absorption was completely blocked to basal level by the pure estrogen receptor (ER) antagonist ICI 182780. In contrast, ICI 182780 did not antagonize calcitriol-enhanced intestinal calcium absorption. Our findings suggest that estrogen stimulates intestinal calcium absorption via an ER.
Age-Related Changes in Bone Turnover in Men
Authors: Fatayerji D. , Dr. Eastell R. 
Published: April 2006

Abstract
Biochemical markers of bone turnover can be used to study the pathophysiology of osteoporosis. So far there have been few such studies in men. The aims of this study were to determine the effect of aging on bone turnover and to identify which hormones might regulate bone turnover in men. We studied 178 healthy Caucasian men, ages 20–79 years (30 per decade). The data for the effect of age on bone turnover was best fit by a quadratic function (nadirs at age 56, 57, 53, 39, and 58 years for intact propeptide of type I procollagen, osteocalcin, bone alkaline phosphatase, free deoxypyridinoline, and cross-linked N-telopeptides of type I collagen, respectively). For most markers, bone turnover tended to be highest in the third decade, lowest in the fifth and sixth decade, with a small increase in some markers in the eighth decade. Insulin-like growth factor-I (IGF-I), insulin-like growth factor binding protein-3, dehydroepiandrosterone sulfate, testosterone, estradiol, and free androgen index all decreased significantly with age (54, 17, 76, 26, 33, and 57%, respectively), while sex hormone binding globulin and parathyroid hormone increased significantly with age (62% and 43%). IGF-I and sex hormones were positively correlated with bone turnover, and this association was stronger in young men than older men. In conclusion, increased IGF-I and sex hormones may be associated with increased bone turnover in young men, with less influence on bone turnover in older men.
Interleukin-17: A New Bone Acting Cytokine In Vitro
Authors: Van Bezooijen Rutger L. , Farih-Sips Hetty C. M. , Papapoulos Socrates E. , Löwik Clemens W. G. M. 
Published: April 2006

Abstract
Interleukin-17 (IL-17) is a recently cloned cytokine that is exclusively produced by activated T cells, but its receptor has been found on several cells and tissues. Like other proinflammatory cytokines produced by activated T cells, IL-17 may affect osteoclastic resorption and thereby mediate bone destruction accompanying some inflammatory diseases. In the present study, we investigated whether osteogenic cells possess the receptor for IL-17 (IL-17R) and whether IL-17 affects osteoclastic resorption. We found that IL-17R mRNA is expressed both in mouse MC3T3-E1 osteoblastic cells and fetal mouse long bones, suggesting that osteogenic cells may be responsive to IL-17. In fetal mouse long bones, IL-17 had no effect on basal and IL-1β–stimulated osteoclastic bone resorption, but when given together with tumor necrosis factor-α (TNF-α) it increased bone resorption dose dependently in serum-free conditions. In addition, IL-17 increased TNF-α–induced IL-1α, IL-1β, and IL-6 mRNA expression in fetal mouse metatarsals and IL-1α and IL-6 mRNA expression in MC3T3-E1 cells. In conclusion, IL-17R mRNA was expressed by mouse osteoblastic cells and fetal mouse long bones, and IL-17 in combination with TNF-α, but not IL-1β, increased osteoclastic resorption in vitro. IL-17 may therefore affect bone metabolism in pathological conditions characterized by the presence of activated T cells and TNF-α production such as rheumatoid arthritis and loosening of bone implants.
Differentiation of Human Marrow Stromal Precursor Cells: Bone Morphogenetic Protein-2 Increases OSF2/CBFA1, Enhances Osteoblast Commitment, and Inhibits Late Adipocyte Maturation
Authors: Gori Francesca , Thomas Thierry , Hicok Kevin C. , Spelsberg Thomas C. , Riggs B. Lawrence 
Published: April 2006

Abstract
Because regulation of the differentiation to osteoblasts and adipocytes from a common progenitor in bone marrow stroma is poorly understood, we assessed effects of bone morphogenetic protein-2 (BMP-2) on a conditionally immortalized human marrow stromal cell line, hMS(2–6), which is capable of differentiation to either lineage. BMP-2 did not affect hMS(2–6) cell proliferation but enhanced osteoblast differentiation as assessed by a 1.8-fold increase in expression of OSF2/CBFA1 (a gene involved in commitment to the osteoblast pathway), by increased mRNA expression and protein secretion for alkaline phosphatase (ALP), type I procollagen and osteocalcin (OC) (except for OC protein), and by increased mineralized nodule formation. Transient transfection with Osf2/Cbfa1 antisense oligonucleotide substantially reduced BMP-2–stimulated expression of ALP mRNA and protein. The effects of BMP-2 on adipocyte differentiation varied: expression of peroxisome proliferator-activated receptor γ2 (a gene involved in commitment to the adipocyte pathway) was unchanged, mRNA expression of the early differentiation marker, lipoprotein lipase, was increased, and mRNA and protein levels of the late differentiation marker, leptin, and the formation of cytoplasmic lipid droplets were decreased. Thus, by enhancing osteoblast commitment and by inhibiting late adipocyte maturation, BMP-2 acts to shunt uncommitted marrow stromal precursor cells from the adipocyte to the osteoblast differentiation pathway.
Renal Chloride Channel, CLCN5, Mutations in Dent's Disease
Authors: Cox Jeremy P. D. , Yamamoto Katsusuke , Christie Paul T. , Wooding Carol , Feest Terry , Flinter Frances A. , Goodyer Paul R. , Leumann Ernst , Neuhaus Thomas , Reid Christopher , Williams Paul F. , Wrong Oliver , Thakker Rajesh V. 
Published: April 2006

Abstract
Dent's disease is an X-linked renal tubular disorder characterized by low-molecular-weight proteinuria, hypercalciuria, nephrocalcinosis, nephrolithiasis, and renal failure. Patients with Dent's disease may also suffer from rickets and other features of the renal Fanconi Syndrome. Patients may have mutations in the X-linked renal chloride channel gene, CLCN5, which encodes a 746-amino-acid protein with 12–13 transmembrane domains. We have investigated the 11 coding exons of CLCN5 for mutations in eight unrelated patients with Dent's disease. Leukocyte DNA was used for the polymerase chain reaction amplification of CLCN5 and the products analyzed for single-stranded conformational polymorphisms (SSCPs). Abnormal SSCPs were sequenced and revealed eight mutations. These consisted of three nonsense mutations (Arg34Stop, Arg648Stop, Arg704Stop), four deletions involving codons 40, 86, 157, and 241, and one acceptor splice consensus sequence mutation tgcag → tgaag. The mutations were confirmed either by restriction endonuclease or sequence-specific oligonucleotide hybridization analysis. In addition, an analysis of 110 alleles from 74 unrelated normal individuals demonstrated that the DNA sequence changes were not common polymorphisms. All of the mutations predict truncated chloride channels that are likely to result in a functional loss. Thus, our findings expand the spectrum of CLCN5 mutations associated with Dent's disease and the results will help to elucidate further the functional domains of this novel chloride channel.
A Dose-Finding Study of Zoledronate in Hypercalcemic Cancer Patients
Authors: Body J. J. , Lortholary A. , Romieu G. , Vigneron A. M. , Ford J. 
Published: April 2006

Abstract
Zoledronate is a new heterocyclic imidazole bisphosphonate that is the most potent bisphosphonate administered in humans because it is 100–850 times more potent than pamidronate, according to in vitro or animal models of bone resorption. We conducted an open-label, dose-finding, single-dose phase I study in tumor-induced hypercalcemia (TIH), which has been similarly used as a model to determine the active doses of other bisphosphonates. The primary objective was to determine, with a dose escalation schedule, two nontoxic dose levels of zoledronate able to induce normocalcemia in at least 80% of patients with TIH after rehydration (corrected Ca for albumin levels ≥2.75 mmol/l). Based on estimates of potency, the starting dose was 0.002 mg/kg, and further tested doses were 0.005, 0.01, 0.02, and 0.04 mg/kg. To obtain a more precise estimate of the response rate, we treated 10 more patients at the highest of the two effective dose levels. The median infusion time of zoledronate was 30 minutes. Thirty out of the 33 treated patients were evaluable for efficacy. Thirty percent of the patients had breast cancer and 54% had metastatic bone involvement. For all groups combined, mean Ca levels at baseline was 3.0 mmol/l. The two effective dose levels were 0.02 mg/kg and 0.04 mg/kg. Five out of five patients became normocalcemic after 0.02 mg of zoledronate/kg and 14 out of 15 after 0.04 mg of zoledronate/kg. The success rate of the latter dose was thus 93% (95% confidence interval [CI] 68–100%). At this dose, the first day of normocalcemia was day 2 or 3 for all but one patient. The duration of normocalcemia for the two effective doses could be assessed in nine patients; seven patients remained normocalcemic throughout the trial (32–39 days). The fall in serum Ca was accompanied by a marked fall in fasting urinary Ca excretion. Zoledronate was well tolerated: 7 out of 33 patients developed transient hypophosphatemia, and 3 developed transient hypocalcemia. The only clinically detectable side effect was an increase in body temperature occurring in 10 (30%) patients. In summary, very low doses of zoledronate (0.02 mg/kg and 0.04 mg/kg, i.e., 1.2 mg and 2.4 mg for a 60-kg individual, respectively) administered by a short-time infusion effectively treated patients with TIH. The fall in serum Ca was rapid, and normocalcemia was often maintained for several weeks. Zoledronate was well tolerated. Future trials will determine whether prolonged treatment with this potent compound can have greater effects on the skeletal morbidity rate in patients with tumor bone disease than can be achieved with currently available bisphosphonates.
Development and Characterization of a Human In Vitro Resorption Assay: Demonstration of Utility Using Novel Antiresorptive Agents
Authors: James Ian E. , Lark Michael W. , Zembryki Denise , Lee-Rykaczewski Elizabeth V. , Hwang Shing Mei , Tomaszek Thaddeus A. , Belfiore Pietro , Gowen Maxine 
Published: April 2006

Abstract
A human in vitro resorption assay has been developed using osteoclastoma-derived osteoclasts and used to evaluate novel antiresorptive agents including antagonists of the αvβ3 integrin, and inhibitors of cathepsin K and the osteoclast ATPase. The potency of novel compounds in the in vitro resorption assay correlates with functional assays for each class of inhibitor: the human αvβ3-mediated cell adhesion assay for the vitronectin receptor antagonists (r2 = 0.82), the chick osteoclast vacuolar ATPase enzyme assay for the H+-ATPase inhibitors (r2 = 0.77) and the recombinant human cathepsin K enzyme assay for the cathepsin K inhibitors (r2 = 0.80). Cell suspensions, rich in osteoclasts, are prepared by collagenase digestion of the tumor tissue. These cells can be stored long-term in liquid nitrogen and upon thawing maintain their bone-resorbing phenotype. The cryopreserved cells can be cultured on bovine cortical bone for 24–48 h and resorption can be measured by either confocal microscopy or biochemical assays. The resorptive activity of osteoclasts derived from a number of tumors can be inhibited reproducibly using a number of mechanistically unique antiresorptive compounds. In addition, the measurement of resorption pits by laser confocal microscopy correlates with the release of type I collagen C-telopeptides or N-telopeptides, as measured by enzyme-linked immunosorbent assay. Resorption can be measured reproducibly using a 48-h incubation of osteoclasts on bone slices, or a 24-h incubation with bone particles. This in vitro human osteoclast resorption assay provides a robust system for the evaluation of inhibitors of osteoclastic function that may be developed for the treatment of metabolic bone diseases such as osteoporosis.
Morphometric Dual-Energy X-Ray Absorptiometry of the Spine: Report of a Large Series and Correlation with Axial Bone Mineral Density
Authors: Bianco Antonio C. , Malvestiti Luiz F. , Gouveia Cecilia H. A. , Wehba Salim , Lewin Shlomo , Marone Marilia M. S. 
Published: April 2006

Abstract
We studied vertebral morphometry and its relation to bone mineral density (BMD) in normal Brazilian women (n = 605). All women (age 22–97 years) were ambulatory and healthy. A lateral spine scan was done for morphometric X-ray absorptiometry using an imaging densitometer. In 429 of these women, BMD of the spine and proximal femur also were measured using dual-energy X-ray absorptiometry. All women were white with mean (± 1 SD) age of 53.7 (± 9.5) years. About 21% of the women over 50 years had a T score for spine BMD lower than –2.5 SD, and 7% had a femoral neck BMD below this osteoporosis threshold. Vertebral heights (anterior, HA; middle, HM; and posterior, HP) and ratios (HA/HP and HM/HP) were assessed. There was no systematic difference between younger (20–49 years) and older (50+ years) women in heights or ratios. The vertebral heights were normalized for those observed in each individual case for the L2–L4 sequence. This normalization was adequate for all vertebral heights; the Z score averaged about +0.1. The average Z score for HA/HP was +0.01, but that for the HM/HP was −0.72, indicating that the latter ratio might differ from the reference population used (white American and European women). We observed a small positive correlation between vertebral heights and spine or femur BMD, but this was due entirely to the influence of body size on BMD. On a group basis, the HM/HP showed a significant association with axial BMD; the 1 SD difference between the lowest and highest quartile was associated with a difference of 8–15% (0.5–1.0 SD) in axial BMD.
A Cross-Sectional Study of Smoking and Bone Mineral Density in Premenopausal Parous Women: Effect of Body Mass Index, Breastfeeding, and Sports Participation
Authors: Jones Graeme , Scott Fiona Sara 
Published: April 2006

Abstract
The objective of this cross-sectional study was to describe the relationship between cigarette smoking, effect modifiers, and bone density in premenopausal parous women. We studied a sample of 276 women (mean age 33 years) from Southern Tasmania. The study factors were cigarette smoking, body mass index (BMI), sports participation, and breastfeeding history. Bone mineral density was measured utilizing an Hologic QDR 2000 densitometer and converted to Z scores using the group mean and variance. There were 118 current smokers and 158 nonsmokers. Smokers had lower bone mass at all sites (femoral neck, −0.32 SD, 95% confidence interval [CI] −0.60 to −0.04; lumbar spine, −0.49 SD, 95% CI −0.76 to −0.22; total body, −0.40 SD, 95% CI −0.66 to −0.14). Stratifying by BMI revealed that this association was only present, but greater in magnitude, for those with a BMI &lt;25 kg/m2. Smokers who had breastfed at least one child had an additional deficit in bone mass (femoral neck, −0.48 SD, 95% CI −0.89 to −0.07; lumbar spine, −0.39 SD, 95% CI −0.80 to 0.02; total body, −0.37 SD, 95% CI −0.77 to 0.06) while smokers who took part in competitive sport had significant increments in bone mass (femoral neck, 0.74 SD, 95% CI 0.31 to 1.17; lumbar spine, 0.48 SD, 95% CI 0.03 to 0.93; total body, 0.42 SD, 95% CI 0.00 to 0.84). Neither of these two associations were present in nonsmokers. In conclusion, current smoking was associated with substantial deficits in bone mass in our sample of women, particularly those with a BMI &lt;25 kg/m2. In addition, smoking may prevent the usual postweaning recovery phase of bone after breastfeeding while sports participation may offset the negative effect of smoking on bone mass. These observations need to be confirmed in longitudinal studies but they imply that past studies of smoking in this age group may have missed important associations as they did not consider possible effect modifiers.
Altered Postnatal Expression of Insulin-Like Growth Factor-I (IGF-I) and Type X Collagen Preceding the Perthes' Disease–Like Lesion of a Rat Model
Authors: Kikkawa Masanori , Imai Shinji , Hukuda Sinsuke 
Published: April 2006

Abstract
The spontaneously hypertensive rat (SHR) is a widely used animal model for the study of hypertension. It also exhibits an osteonecrosis of the femoral epiphysis that resembles the clinical features of Perthes' disease in humans. In this rat model, occlusion of the epiphyseal vessels occurs as a result of a breakdown of the mechanically vulnerable epiphysis. The postnatal development of the epiphysis recapitulates the serial events of the endochondral ossification (i.e., cartilage formation), chondrocyte hypertrophy, cartilage mineralization, vascularization, and introduction of osteoblasts that form the secondary ossification center within the epiphysis. In the present study, a detailed radiographic and histological analysis demonstrates that the osteonecrosis is preceded by a disturbance of the cartilage mineralization and a disturbance of the ossification, despite a normal hypertrophy of the epiphyseal cartilage. These observations suggest that abnormal development of the femoral epiphysis occurs much earlier than manifestation of the osteonecrosis. They lead us to a hypothesis that yet-unclarified transitional events between the cartilage hypertrophy and the cartilage mineralization may be affected in SHRs. Type X collagen is a developmentally regulated matrix molecule that is implicated in the mineralization of the hypertrophied chondrocytes. We show that the expression of type X collagen during epiphyseal ossification is delayed in SHRs (vs. normal controls), suggesting disturbed growth and/or differentiation of the epiphyseal chondrocytes. Postnatal growth and differentiation of the chondrocytes at least partly depend on insulin-like growth factor-I (IGF-I), which is produced by the chondrocytes in response to the pituitary growth hormone and stimulates cartilage growth in situ. The present study demonstrates an altered IGF-I expression during early postnatal life in SHRs and suggests that the altered IGF-I expression as well as the following delay in upregulation of type X collagen may cause the mechanical vulnerability of the femoral epiphysis in SHRs.