bluuebunny/crossref_metadata_2025 huggingface dataset:
The Infrared Spectra of Triplet 4-Phenylbenzophenone
Authors: George Michael W , Kato Chihiro , Hamaguchi Hiro-o
Published: April 2006

Microsecond time-resolved IR (TRIR) spectroscopy has been used to record the infrared spectra of the ππ* triplet states of 4-phenylbenzophenone and its 18O and 13C analogues. There is a definite shift in the frequency to lower wavenumber of the ν(CO) vibration. The intensity of the C-O vibration is similar in the ground and excited state. This is the first report of the infrared spectra of the excited triplet state of aromatic carbonyl compounds in room temperature solution.
A Neutron Emission from Lithium Niobate Fracture
Authors: Shirakawa Toshiaki , CHiba Masami , Fujii Masatoshi , Sueki Keisuke , Miyamoto Shinya , Nakamitu Yuki , Toriumi Hideyuki , Uehara Torahiko , Miura Hiroaki , Watanabe Toshihiro , Fukushima Kenji , Hirose Tachishige , Seimiya Tutomu , Nakahara Hiromichi
Published: April 2006

We studied neutron emission from a crushing process of a Lithium-Niobate(LiNbO3) single crystal in deuterium gas atmosphere. We observed excess neutrons 3 counts/h with a confidence level of 99.95% that correspond 120 neutrons/h emission from process.
Generation of Acyl Radicals from 1-Oxidoalkylidenechromium(0) Complexes by Treatment with Bis(2,2,6,6-tetramethyl-3,5-heptanedionato)copper(II) and Their Reactions with Olefins
Authors: Sakurai Hidehiro , Narasaka Koichi
Published: April 2006

Tetramethylammonium pentacarbonyl(1-oxidoalkylidene)chromium(0) complexes are oxidized with bis(2,2,6,6-tetramethyl-3,5-heptanedionato)copper(II) to generate acyl radicals which react with electron-deficient olefins, giving intermolecular addition products.
In Situ Observation of the Au-Hg Alloy Formation on a Gold Electrode Surface by Atomic Force Microscopy
Authors: Yang Xiaomin , Tonami Kousuke , Nagahara Larry Akio , Hashimoto Kazuhito , Wei Yu , Fujishima Akira
Published: April 2006

Bulk electrochemical deposition of mercury on Au(111) electrode surface in an acidic media, resulting in the formation of a Au-Hg alloy, has been studied in-situ by atomic force microscopy (AFM). AFM images revealed that small alloy protrusions form initially next to the Au grain boundaries and gradually increase in size with increased deposition time. More importantly, these protrusions are always accompanied by the dissolution of gold at the grain boundaries, leaving many apparent pits visible on the amalgamated surface.
Direct and Electrophilic Preparation of α-Thiocyanatoketones and Aldehydes Using Thiocyanatotrimethylsilane and Sulfuryl Chloride
Authors: Tanabe Yoo , Makita Takuya , Mori Kei
Published: April 2006

The thiocyanato (-SCN) group was directly and regioselectively introduced into the α-position of ketones, aldehydes, and aldols in an electrophilic manner by the combined use of thiocyanatotrimethylsilane and sulfuryl chloride with or without cyclic sec-amine catalysts under mild reaction conditions.
Synthesis and Structure of Novel Metallacycle Complexes of Ruthenium Derived from 1,1′-Dialkynylferrocene
Authors: Onitsuka Kiyotaka , Miyaji Kayoko , Adachi Tomohiro , Yoshida Toshikatsu , Sonogashira Kenkichi
Published: April 2006

The reaction of 1,1′-bis(phenylethynyl)ferrocene with Ru3(CO)12 gave a novel trinuclear ruthenacycle complex having a [2]ferrocenophane skeleton. A similar treatment of 1,1′-bis(trimethylsilylethynyl)ferrocene afforded not only a trinuclear ruthenacycle analog but also a dinuclear ruthenacycle complex that also possessed a [2]ferrocenophane skeleton. These complexes were characterized by means of spectroscopic and X-ray diffraction analyses.
Aculeoside A, a Novel Steroidal Saponin Containing a Deoxyaldoketose from Ruscus aculeatus
Authors: Horikawa Tomohiko , Mimaki Yoshihiro , Kameyama Aiko , Sashida Yutaka , Nikaido Tamotsu , Ohmoto Taichi
Published: April 2006

A novel steroidal saponin, named aculeoside A, embracing a deoxyaldoketose, 6-deoxy-d-glycero-l-threo-4-hexosulose, was isolated from the underground parts of Ruscus aculeatus. The structure was determined by extensive 2D NMR analysis and hydrolysis. Aculeoside A was active as a cyclic AMP phosphodiesterase inhibitor.
Synthesis and Properties of New Donors. 1,6-Methano[10]annulene and Naphthalene Derivatives with Tetrathiafulvalene Substituents
Authors: Kux Ulrich , Iyoda Masahiko
Published: April 2006

New donors, containing one or two tetrathiafulvalenes at 2-, 2,7- and 2,10-positions of 1,6-methano[10]annulene or at 1,8-positions of naphthalene, have been synthesized. Through-space and/or through-bond interactions between TTF units in these compounds have been investigated by means of cyclic voltammetry.
Organo-Rhodium Complex with Tridentate Biradical Ligand, [Rh(Cp*)(bisnitpy)](PF6)2
Authors: Oshio Hiroki , Ohto Akihiro , Fujisawa Jun’ichi , Watanabe Takashi , Ito Tasuku , Isobe Kiyoshi
Published: April 2006

A new Rh(III) complex, [Rh(Cp*)(bisnitpy)](PF6)2 (Cp* = η5-C5Me5 and bisnitpy = 2,6-bis(1′-oxyl-3′-oxido-4′,4′,5′,5′-tetramethyl-4′,5′-dihydro-1′H-imidazol-2′-yl)pyridine), has been prepared, which is the first example of organometallic complex having nitronyl nitroxide ligand. X-ray structure and magnetic property of the title complex are reported.
Estimation of Total Infrared Intensities of Fluorinated Ethyl Methyl Ethers
Authors: Suga Atsuo , Mochizuki Yuji , Nagasaki Noritaka , Gotoh Yoshihiko , Ito Haruaki , Yamashita Shiro , Uchimaru Tadafumi , Sugie Masaaki , Sekiya Akira , Kondo Shigeo , Aoyagi Mutsumi
Published: April 2006

An excellent linear correlation was found between calculated and experimental total infrared intensities in the region of 500–2000 cm−1 for five partially fluorinated ethyl methyl ethers, HFC-134a, and CFC-11. The calculated results using ab initio molecular orbital method with D95V**(Huzinaga-Dunning’s valence double zeta) show the best linear correlation among basis sets examined in this study. The correlation coefficient with D95V** is 0.9993 although the calculated values are on the average 32% higher than experimental ones.
Glass Formation and Phase Transition of Novel π-Electron Starburst Molecules, 1,3,5-Tris(phenyl-2-thienylamino)benzene and 1,3,5-Tris(phenyl-3-thienylamino)benzene
Authors: Ueta Emi , Nakano Hideyuki , Shirota Yasuhiko
Published: April 2006

Novel π-electron starburst molecules, 1,3,5-tris(phenyl-2-thienylamino)benzene (α-TPTAB) and 1,3,5-tris(phenyl-3-thienylamino)benzene (β-TPTAB), are found to form amorphous glasses with well-defined glass-transition temperatures of 38 and 46 °C, respectively, while 1,3,5-tris(diphenylamino)benzene instantly crystallizes. The result leads to a concept of “increasing the number of conformers of nonplanar molecules” for a molecular design of amorphous molecular glasses. The glasses of α-TPTAB and β-TPTAB are found to be transformed finally into crystals with the highest melting points via metastable crystals on heating.
Utility of an Inverse-Matrix Technique in the Fast Atom Bombardment Mass Spectrometry-Based Structural Determination of 2-Substituted 1,3-Bis(benzotriazolyl)isoindolines
Authors: Isa Kimio , Takahashi Ichiro , Tsuzuki Mikio , Yokota Hiroshi , Kitajima Hidehiko
Published: April 2006

Molecular ions (M+’s) of reactive synthetic intermediates (1,3-bis(benzotriazolyl)isoindolines) can be monitored with certainty through a new sample-sorting technique in the fast atom bombardment mass spectrometry (FABMS).
How Do Nitrogen Bases Accelerate the Decomposition of H2O2 in a Manganese Porphyrin Dimer Catalyst? Quantitative Evaluation of the Base Effects by Its Axial Coordination vs. General-base Catalysis
Authors: Naruta Yoshinori , Sasayama Masa-aki
Published: April 2006

Kinetic analysis of the dismutation reaction of H2O2 with a cofacial manganese porphyrin dimer gave the separate evaluation of two roles of nitrogen bases on the decomposition of H2O2 and the axial coordination of bases enhances the reaction of H2O2 with the manganese porphyrin in 6.6 times larger than by a general-base catalysis.
Distribution and Trend of Chlorodifluoromethane (HCFC-22) in the Atmosphere
Authors: Chen Limin , Makide Yoshihiro , Tominaga Takeshi
Published: April 2006

Atmospheric concentration of HCFC-22 in the Northern and Southern Hemispheres over the past 15 years was measured by using an oxygen sensitized ECD (electron capture detector). The global concentration increased by about 5.2 ± 0.4 pptv (pptv = 10−12 v/v) per year for the period 1980–1988, and about 10.3 ± 0.2 pptv per year for the period 1988–1994. The observed result until 1988 was consistent with the mixing ratios calculated by 2-box model based on the statistical figures of production and emission with 14.0 ± 1.5 years lifetime. However, the observed data suggest that the statistical figures of HCFC-22 emission have been underestimated since 1988.
Effects of Sex and Age on Bone Microstructure at the Ultradistal Radius: A Population-Based Noninvasive In Vivo Assessment
Authors: Khosla Sundeep , Riggs B Lawrence , Atkinson Elizabeth J , Oberg Ann L , McDaniel Lisa J , Holets Margaret , Peterson James M , Melton L Joseph
Published: April 2006

In a population-based cross-sectional study, we examined effects of sex and age on bone microstructure at the wrist using high-resolution 3-D pQCT. Compared with women, men had thicker trabeculae in young adulthood and had less microstructural damage with aging. These findings may contribute to the virtual immunity of men to age-related increases in wrist fractures.

Introduction: Although changes in bone microstructure contribute to fracture risk independently of BMD, it has not heretofore been possible to assess this noninvasively in population-based studies.

Materials and Methods: We used high-resolution 3-D pQCT imaging (voxel size, 89 μm) to define, in a random sample of women (n = 324) and men (n = 278) 21–97 years of age, sex and age effects on bone microstructure at the wrist.

Results: Relative to young women (age, 20–29 years), young men had greater trabecular bone volume/tissue volume (BV/TV; by 26%, p = 0.001) and trabecular thickness (TbTh; by 28%, p < 0.001) but similar values for trabecular number (TbN) and trabecular separation (TbSp). Between ages 20 and 90 years, cross-sectional decreases in BV/TV were similar in women (−27%) and in men (−26%), but whereas women had significant decreases in TbN (−13%) and increases in TbSp (+24%), these parameters had little net change over life in men (+7% and −2% for TbN and TbSp, respectively; p < 0.001 versus women). However, TbTh decreased to a greater extent in men (−24%) than in women (−18%; p = 0.010 versus men).

Conclusions: Whereas decreases with age in trabecular BV/TV are similar in men and women, the structural basis for the decrease in trabecular volume is quite different between the sexes. Thus, over life, women undergo loss of trabeculae with an increase in TbSp, whereas men begin young adult life with thicker trabeculae and primarily sustain trabecular thinning with no net change in TbN or TbSp. Because decreases in TbN have been shown to have a much greater impact on bone strength compared with decreases in TbTh, these findings may help explain the lower life-long risk of fractures in men, and specifically, their virtual immunity to age-related increases in distal forearm fractures.
Identification of Multiple Osteoclast Precursor Populations in Murine Bone Marrow
Authors: Jacquin Claire , Gran Diane E , Lee Sun Kyeong , Lorenzo Joseph A , Aguila Hector L
Published: April 2006

Murine BM was fractionated using a series of hematopoietic markers to characterize its osteoclast progenitor populations. We found that the early osteoclastogenic activity in total BM was recapitulated by a population of cells contained within the CD11b−/low CD45R−CD3−CD115high fraction.

Introduction: Osteoclasts are of hematopoietic origin and they have been shown to share the same lineage as macrophages. We further characterized the phenotype of osteoclast progenitor populations in murine bone marrow (BM) by analyzing their cell surface markers.

Materials and Methods: We used fluorescence-activated cell sorting (FACS) to identify the subsets of BM cells that contained osteoclast progenitors. We fractionated BM according to several markers and cultured the sorted populations for a period of 2–6 days with macrophage-colony stimulating factor (M-CSF) and RANKL. The numbers of multinucleated osteoclast-like cells (OCLs) that formed in the cultures were counted.

Results: We found that the CD45R−CD11b−/low population recapitulated the early osteoclastogenic activity of total BM. In addition, although previous experiments indicated that osteoclastogenic activity was enriched within the CD45R+ population, we found that highly purified CD45R+ BM was incapable of differentiating into osteoclasts in vitro. We also found that CD45R−CD11bhigh BM cells were an inefficient source of osteoclast progenitors. However, CD11b was transiently upregulated by cells of the CD45R−CD11b−/low fraction early (within 24 h) during culture with M-CSF. Finally, further fractionation of BM using CD115 and CD117 showed that, as osteoclast precursor cells matured, they downregulate CD117 but remain CD115+. Curiously, pure populations of CD117− (CD115high) cells isolated fresh from BM have low osteoclastogenic activity in vitro.

Conclusions: We provided a refined analysis of the precise subpopulations of murine BM that are capable of differentiating into OCLs in vitro when treated with M-CSF and RANKL.
Population-Based Analysis of the Relationship of Whole Bone Strength Indices and Fall-Related Loads to Age- and Sex-Specific Patterns of Hip and Wrist Fractures
Authors: Riggs B Lawrence , Melton L Joseph , Robb Richard A , Camp Jon J , Atkinson Elizabeth J , Oberg Ann L , Rouleau Peggy A , McCollough Cynthia H , Khosla Sundeep , Bouxsein Mary L
Published: April 2006

In an age- and sex-stratified population sample (n = 700), we estimated fall-related loads and bone strength indices at the UDR and FN. These load/strength ratios more closely simulated patterns of wrist and hip fractures occurring in the same population than did measurement of vBMD.

Introduction: Areal BMD measurements, although associated with fracture risk, incompletely explain patterns of fragility fractures. Moreover, population-based assessments relating applied loads and whole bone strength to fracture patterns have not been made.

Materials and Methods: Using QCT, we assessed volumetric BMD (vBMD), cross-sectional geometry, and axial (EA) and flexural (EI) rigidities (indices of bone's resistance to compressive and bending loads, respectively) at the ultradistal radius (UDR) and femoral neck (FN) and estimated the loads applied to the wrist and hip during a fall. We used fall load (FL)/bone strength ratios to estimate fracture risk.

Results: vBMD in young adults was similar between sexes. Decreases in vBMD over life were also similar (30% and 28%) at UDR but were somewhat greater (46% and 34%) at FN in women versus men, respectively. In young adults, FL/strength ratios at UDR were 32–51% lower (better) in men than in women and increased (worsened) over life less in men (+4% to +22%) than in women (+20% to +33%). In young adults, FL/strength ratios at FN were only marginally better in men than in women but worsened less over life in men (+22% to +36%) than in women (+40% to +62%).

Conclusions: The 6:1 female preponderance and the virtual immunity of men for age-related increases in wrist fractures are largely explained by the more favorable FL/strength ratios at UDR in young adult men (because of larger bone size and more favorable geometry) versus women and to maintaining this advantage over life. The 2-fold lower incidence of hip fractures in men versus women is largely explained by age-related increases (worsening) of FL/bone strength ratios that are only one-half of the increases in women. The moderate increases in these ratios with aging are insufficient to explain the >4-fold increase in hip fracture incidence after age 75 in both sexes, suggesting contributions of other factors, especially the well-documented increased frequency of injurious falls among the elderly.
Incidence and Predictors of Fractures in Children After Solid Organ Transplantation: A 5-Year Prospective, Population-Based Study
Authors: Helenius Ilkka , Remes Ville , Salminen Sari , Valta Helena , Mäkitie Outi , Holmberg Christer , Palmu Petri , Tervahartiala Pekka , Sarna Seppo , Helenius Miia , Peltonen Jari , Jalanko Hannu
Published: April 2006

In this population-based prospective follow-up study, children undergoing solid organ transplantation had a highly elevated risk for fractures: The incidence of all fractures was 6-fold higher (92 versus 14 fractures/1000 persons/year; p < 0.001) and vertebral fractures was 160-fold higher (57 versus 0.35 fractures/1000 persons/year; p < 0.001) in the study group compared with the control population. Thus, screening of vertebral fractures at regular intervals is recommended, and preventive strategies should be studied.

Introduction: The incidence and predictors of fractures after solid organ transplantation are not well documented in the pediatric age group.

Materials and Methods: A total of 196 children, which is 93% of patients surviving kidney, liver, and heart transplantation in our country, participated in a retrospective chart review at enrollment followed by a 5-year prospective follow-up study between January 1999 and December 2004. Hospital and medical records were reviewed. All children underwent clinical examinations and answered questionnaires concerning fracture history at the beginning and at the end of the prospective follow-up. Radiographs of the thoracic and lumbar spine were obtained. The fracture incidence was compared with data obtained from public health registries.

Results: Seventy-five (38%) of the transplant patients suffered from a total of 166 fractures after organ transplantation. The incidence of all fractures was 6-fold higher (92 versus 14 fractures/1000 persons/year; p < 0.001) and vertebral fractures was 160-fold higher (57 versus 0.35 fractures/1000 persons/year; p < 0.001) in the study group compared with the control population. The age- and sex-adjusted hazard ratios (95% CI) were 61.3 (40.7-92.4) for vertebral, 17.9 (8.96-35.8) for symptomatic vertebral, 0.99 (0.65-1.50) for nonvertebral, and 2.90 (2.25-3.73) for all fractures in the patients compared with the control population. In a multivariate analysis, older age (hazard ratio [95% CI]; 2.02 [1.07-3.83]), male sex (2.15 [1.22-3.81]), liver transplantation (1.78 [1.01-3.14]), and fractures before transplantation (2.02 [0.92-4.47]) were the most significant independent risk factors.

Conclusions: Children undergoing solid organ transplantation have a highly elevated risk for fractures. Screening of vertebral fractures at regular intervals is recommended, and preventive strategies should be studied.
On Our Age-Related Bone Loss: Insights from a New Paradigm
Authors: Frost Harold M.
Published: April 2006

Bone strength and “mass” normally adapt to the largest voluntary loads on bones. The loads come from muscles, not body weight. Bone modeling can increase bone strength and “mass,” bone remodeling can conserve or reduce them, and each can turn ON and OFF in response to its own threshold range of bone strains. During growth, the loads on bones from body weight and muscle forces increase, and modeling correspondingly increases bone strength and “mass.” In young adults those loads usually plateau, so bone strength can “catch up” and modeling can turn OFF. Meanwhile remodeling keeps existing bone. After about 30 years of age, muscle strength usually decreases. In aging adults this would put bones that had adapted to stronger young-adult muscles into partial disuse and make remodeling begin to reduce their strength and “mass,” as disuse regularly does in experimental situations in other mammals, both growing and adult. Those changes associate strongly with the size of the bone strains caused by the loads on bone. While nonmechanical effects associated with aging should contribute to that age-related bone loss too, a new skeletal paradigm suggests the above mechanical influences would dominate control of the process in time and anatomical space.
Chondrocytes Are Regulated by Cellular Adhesion Through CD44 and Hyaluronic Acid Pathway
Authors: Ishida Osamu , Tanaka Yoshiya , Morimoto Isao , Takigawa Masaharu , Eto Sumiya
Published: April 2006

The articular cartilage consists of resident chondrocytes embedded within the extracellular matrix which contains several components such as collagen and hyaluronic acids (HA). CD44 is a major cell surface receptor for HA and is homologous to cartilage-link proteins. Although CD44 is present in cartilage, it is not clear if chondrocytes adhere to HA through CD44 or whether such adhesion changes the function of chondrocytes. We studied the molecular mechanisms of CD44-related chondrocyte adhesion to HA and the effects of such adhesion on chondrocyte function. Experiments were performed using the human chondrosarcoma-derived chondrocyte-like cell line HCS-2/8. Our results showed that (a) HCS-2/8 cells highly expressed CD44; (b) HCS-2/8 cells efficiently adhered to HA without any stimuli; (c) monoclonal antibody (mAb)-blocking studies indicated that adhesion of HCS-2/8 cells to HA was mainly mediated by the CD44/HA pathway; (d) cellular adhesion to HA increased the proliferation of HCS-2/8 cells, independent of transforming growth factor-β (TGF-β), but this was inhibited by CD44 mAb; (e) the adhesion of chondrocytes to HA also induced c-myc mRNA expression and this was also inhibited by CD44 mAb; and (f) the adhesion of cells to HA augmented TGF-β mRNA expression, a process also reduced by CD44 mAb. Thus, HCS-2/8 cells effectively adhered to HA through cell surface CD44. The adhesion was also involved in cellular signaling which induced cellular proliferation and expression of c-myc mRNA as well as TGF-β mRNA expression within the cells. Our results indicate that CD44 on chondrocytes plays an important role in normal and abnormal functions of cartilage through its adhesion to HA, which induces a variety of stimulatory signals to regulate chondrocyte proliferation as well as matrix synthesis in cartilage microenvironment.
Human Stanniocalcin Inhibits Renal Phosphate Excretion in the Rat
Authors: Dr. Wagner Graham F. , Vozzolo Benito L. , Jaworski Ewa , Haddad Michel , Kline Robert L. , Olsen Henrik S. , Rosen Craig A. , Davidson Michael B. , Renfro J. Larry
Published: April 2006

Stanniocalcin (STC) is a glycoprotein hormone first identified in bony fishes where it counteracts hypercalcemia by inhibiting gill calcium uptake and stimulating renal inorganic phosphate (Pi) reabsorption. Human STC (hSTC) has recently been cloned and sequenced and is highly homologous to the fish hormone at the amino acid level. The objective of this study was to examine the possible effects of hSTC on electrolyte homeostasis and renal function in the rat. Recombinant hSTC was expressed in bacteria and purified by metal-ion affinity chromatography and reverse-phase high performance liquid chromatography. Anesthetized animals were given bolus infusions of 1, 5, or 10 nmol hSTC per kilogram of body weight. Control animals received solvent alone. The most effective dosage was 5 nmol/kg, which caused significant reductions in both absolute and fractional phosphate excretion in comparison with control rats. The hSTC had no effect on the renal excretion of other ions, the glomerular filtration rate, renal blood flow, blood pressure, or plasma electrolytes (Na+, K+, Ca2+, Pi, Mg2+). The maximum effect of hSTC on phosphate excretion was observed 60–80 minutes postinjection. Lesser effects were obtained with higher and lower dosages of hormone. When renal cortical brush-border membrane vesicles were isolated from control and hormone-treated animals 80 minutes postinjection, the rate of Na+/Pi cotransport was found to be 40% higher in vesicles from hormone-treated animals (p < 0.01; 5 nmol hSTC/kg). Together, the renal clearance and membrane vesicle data indicate that hSTC participates in the renal regulation of Pi homeostasis in mammals.
High-Impact Exercise Promotes Bone Gain in Well-Trained Female Athletes
Authors: Taaffe Dennis R. , Robinson Tracey L. , Snow Christine M. , Marcus Robert
Published: April 2006

Maximizing peak bone mass, as well as reducing its loss after menopause, is important for the prevention of osteoporosis. One mode of activity, gymnastics training, invokes high impact loading strains on the skeleton which may have powerful osteogenic effects. To examine the role of athletic activity, specifically gymnastics, on bone mineral density (BMD) accretion, we monitored longitudinal changes in regional and whole body BMD in collegiate women gymnasts and competitive athletes whose skeletons are exposed to differential loading patterns: runners and swimmers. Two cohorts were studied. Cohort I = 26 gymnasts (19.7 ± 1.2 years), 36 runners (21.1 ± 2.7 years) and 14 nonathletic women (19.3 ± 1.7 years) followed over an 8-month period. Cohort II = 8 gymnasts (18.9 ± 1.1 years), 11 swimmers (20.0 ± 2.3 years) and 11 nonathletic women (19.0 ± 1.2 years) followed over a 12-month period. Lumbar spine (L2–4), femoral neck, and whole body BMD (g/cm2) were assessed by dual-energy X-ray absorptiometry. For cohort I, the percent change in lumbar spine BMD after 8 months was significantly greater (p = 0.0001) in the gymnasts (2.8 ± 2.4%) than in the runners (−0.2 ± 2.0%) or controls (0.7 ± 1.3%). An increase in femoral neck BMD of 1.6 ± 3.6% in gymnasts was also greater (p < 0.05) than runners (−1.2 ± 3.0%) and approached significance compared with controls (−0.9 ± 2.2%, p = 0.06). For cohort II, gymnasts gained 2.3 ± 1.6% at the lumbar spine which differed significantly (p < 0.01) from changes in swimmers (−0.3 ± 1.5%) and controls (−0.4 ± 1.7%). Similarly, the change at the femoral neck was greater (p < 0.001) in gymnasts (5.0 ± 3.4%) than swimmers (−0.6 ± 2.8%) or controls (2.0 ± 2.3%). The percent change in BMD at any site did not differ between eumenorrheic and irregularly menstruating athletes. These results indicate that bone mineral at clinically relevant sites, the lumbar spine and femoral neck, can respond dramatically to mechanical loading characteristic of gymnastics training in college-aged women. This occurred despite high initial BMD values and was independent of reproductive hormone status. The results provide evidence to support the view that high impact loading, rather than selection bias, underlies high BMD values characteristic of women gymnasts. Because all athletes underwent resistance training throughout the year of study, muscle strengthening activity did not appear to be a significant factor in the skeletal response observed in gymnasts. We conclude that activities resulting in high skeletal impacts may be particularly osteotropic for young women.
Identification and Characterization of the Insulin-like Growth Factor I Receptor in Mature Rabbit Osteoclasts
Authors: Hou Peng , Sato Takuya , Hofstetter Willy , Foged Niels Tækker
Published: April 2006

In this study, the insulin-like growth factor I (IGF-I) receptor was identified in rabbit osteoclasts at mRNA and protein levels by in situ hybridization and autoradiography, respectively. Using highly purified mature osteoclasts, the IGF-I receptor was characterized on the molecular level according to its size and its affinity and number per osteoclast by isolation of the receptor–ligand complex and by binding studies, respectively, and on the cellular level according to the response of mature osteoclasts to IGF-I stimulation. In situ hybridization and autoradiography experiments showed that osteoclasts express IGF-I receptor mRNA and IGF-I binding sites. Chemical cross-linking of125I-IGF-I bound to the purified mature osteoclasts and subsequent sodium dodecyl sulfide-polyacrylamide gel electrophoresis revealed the specific binding of125I-IGF-I in complexes with molecular masses of 130 and 230 kD consistent with binding to the IGF-I receptor. In competition experiments,125I-IGF-I binding to mature osteoclasts was dose-dependently reduced by unlabeled IGF-I in the picomolar range, whereas 20 nM insulin did not reduce the binding of125I-IGF-I binding. The calculated receptor number was 6000 per osteoclast, and the Kd was 0.10 nM. Searching for a role of the IGF-I receptor in mature osteoclasts, we found no significant influence of IGF-I on the levels of the proform of matrix metaloproteinase 9 and tartrate-resistant acid phosphatase. However, the induction of nuclear fragmentation in serum-depleted cultures of purified mature osteoclasts was dose-dependently inhibited by IGF-I in the picomolar range, but not by 1 nM insulin. These data show that functionally active IGF-I receptor is present in mature osteoclasts.
Fractal Properties of Subchondral Cancellous Bone in Severe Osteoarthritis of the Hip
Authors: Dr. Fazzalari N. L. , Parkinson I. H.
Published: April 2006

Primary osteoarthritis of the hip results in changes to the architecture of subchondral cancellous bone. These changes in architecture occur through the action of osteoclasts and osteoblasts in selectively removing and adding bone. The quantitative description of the bone architecture helps in understanding the etiology of primary osteoarthritis. Fractal analysis is a method for describing complex shapes, which is expressed numerically as the fractal dimension. A box counting method was used, where the perimeter of binary profiles of cancellous bone samples was measured for different box sizes. The fractal dimension was the absolute value of the slope of the straight line segments from the plot of the log number of boxes versus the log box size. Cancellous bone samples from two subchondral regions, superior and inferomedial, to the fovea were analyzed from primary severe osteoarthritic specimens taken following total hip replacement surgery (n = 19, aged 51–80 years) and autopsy controls (n = 25, aged 18–90 years). There were three straight line segments identified on the log–log plot, for each subject, indicating a fractal dimension over three different ranges of scale. The results show that in the superior region there is a highly significant difference between the groups (p < 0.0001) for fractal 1 and pivot point 2. The histomorphometry shows significant differences for bone volume/total volume, bone surface/total volume, trabecular separation, and osteoid surface/total volume between groups. In the inferomedial region fractal 1 and fractal 2 are significantly different. For the histomorphometry, trabecular thickness and eroded surface/total volume are significantly different between the groups. The pivot points, i.e., the box size at which the fractal dimension changes, were of similar magnitude to the trabecular thickness and trabecular separation. These data suggest that the fractal geometry analysis of cancellous bone identifies architectural features not easily recognized by conventional bone histomorphometry. The fractal dimension is a descriptor of bone structure which simplifies the description of a complex structure and enables changes in cancellous bone architecture, due to disease, to be identified.
Cloning and Sequencing of Human PEX from a Bone cDNA Library: Evidence for Its Developmental Stage-Specific Regulation in Osteoblasts
Authors: Guo Rong , Quarles L. Darryl
Published: April 2006

Inactivating mutations of the neutral endopeptidase, PEX, have been identified as the cause of X-linked hypophosphatemia (XLH). Though the function of PEX is unknown, current information suggests that impaired renal phosphate conservation in XLH is due to the failure of PEX to either degrade an undefined phosphaturic factor or activate a novel phosphate-conserving hormone. The physiologically relevant target tissue for the XLH mutation has not been identified. An apparent intrinsic defect of osteoblast function in XLH implicates bone as a possible site of PEX expression. In the current investigation, we employed a polymerase chain reaction (PCR) strategy to amplify a PEX cDNA from a human bone cell cDNA library. We found that the human PEX cDNA encodes a 749 amino acid protein belonging to the type II integral membrane zinc-dependent endopeptidase family. The predicted PEX amino acid sequence shares 96.0% identity to the recently cloned mouse Pex cDNA and has 27–38% identity to other members of the metalloendopeptidase family. Using reverse transcriptase (RT)-PCR with PEX-specific primers, we detected PEX transcripts in both human osteosarcoma-derived MG-63 osteoblasts and in differentiated mouse MC3T3-E1 clonal osteoblasts but not in immature MC3T3-E1 preosteoblasts. The association of impaired mineralization of bone in XLH and the apparent developmental stage-specific expression of PEX in osteoblasts suggest that bone is a physiologically relevant site of PEX expression and that PEX may play an active role in osteoblast-mediated mineralization.
The BsmI Vitamin D Receptor Restriction Fragment Length Polymorphism (bb) Influences the Effect of Calcium Intake on Bone Mineral Density
Authors: Kiel Douglas P. , Myers Richard H. , Cupples L. ADRIENNE , Kong Xiang F. , Zhu Xue H. , Ordovas Jose , Schaefer Ernest J. , Felson David T. , Rush David , Wilson Peter W. F. , Eisman John A. , Holick Michael F.
Published: April 2006

Previous studies of the vitamin D receptor (VDR) polymorphisms and bone mineral density (BMD) have suggested that there may be differences in calcium absorption among groups of women with different VDR genotypes, and that the association may be stronger in younger women. To investigate the association between the VDR polymorphisms and BMD, this study was undertaken in the Framingham Study Cohort and a group of younger volunteers. Subjects from the Framingham Study (ages 69–90 years) included those who underwent BMD testing and who had genotyping for the VDR alleles (n = 328) using polymerase chain reaction methods and restriction fragment length polymorphisms with BsmI (B absence, b presence of cut site). A group of younger volunteer subjects (ages 18–68) also underwent BMD testing and VDR genotyping (n = 94). In Framingham Cohort subjects with the bb genotype, but not the Bb or BB genotypes, there were significant associations between calcium intake and BMD at five of six skeletal sites, such that BMD was 7–12% higher in those with dietary calcium intakes greater than 800 mg/day compared with those with intakes <500 mg/day. The data also suggested that BMD was higher in persons with the bb genotype only in the group with calcium intakes above 800 mg/day. No significant differences were found in the Framingham Cohort for age-, sex-, and weight-adjusted BMD at any skeletal site between those with the BB genotype and those with the bb genotype regardless of 25-hydroxyvitamin D levels or country of origin. In the younger volunteers, BMD of the femoral neck was 5.4% higher (p < 0.05) in the bb genotype group compared with the BB group and 11% higher (p < 0.05) in males with the bb genotype compared with the BB group. There were no significant differences at the lumbar spine. In this study, the association between calcium intake and BMD appeared to be dependent upon VDR genotype. The finding of an association between dietary calcium intake and BMD only in the bb genotype group suggests that the VDR genotype may play a role in the absorption of dietary calcium. Studies that do not consider calcium intake may not detect associations between VDR genotype and BMD. In addition, the association between VDR alleles and BMD may become less evident in older subjects.
Tumor-Induced Osteomalacia: Clinical and Basic Studies
Authors: Shane Elizabeth , Parisien May , Henderson Janet E. , Dempster David W. , Feldman Frieda , Hardy Mark A. , Tohme Jack F. , Karaplis Andrew C. , Clemens Thomas L.
Published: April 2006

A patient with classic clinical and biochemical features of tumor-induced osteomalacia (hypophosphatemia, phosphaturia, and undetectable serum concentrations of 1,25-dihydroxyvitamin D [1,25(OH)2D]) was studied before and after resection of a benign extraskeletal chondroma from the plantar surface of the foot. Presurgical laboratory evaluation was notable for normal serum concentrations of calcium, intact parathyroid hormone (PTH), parathyroid hormone-related protein (PTHrP), and osteocalcin, increased serum alkaline phosphatase activity, and frankly elevated urinary cyclic adenosine monophosphate (cAMP) and pyridinium cross-link excretion. Quantitative histomorphometry showed severe osteomalacia and deep erosions of the cancellous surface by active osteoclasts. After resection, serum 1,25(OH)2D normalized within 24 h, while renal tubular phosphorus reabsorption and serum phosphorus did not normalize until days 2 and 3, respectively; serum Ca declined slightly, and serum intact PTH, osteocalcin, and urinary pyridinium cross-link excretion increased dramatically. Urinary cAMP excretion declined immediately after resection and then began to increase concomitant with the increase in serum intact PTH. A second bone biopsy taken 3 months after resection demonstrated complete resolution of the osteomalacia, increased mineral apposition rate (1.09 μ/day), resorption surface (9.2%), mineralizing surface (71%), and bone formation rate (0.83 mm3/mm2/day), and marked decreases in cancellous bone volume (13.1%) and trabecular connectivity compared with the first biopsy. Tumor extracts did not affect phosphate transport in renal epithelial cell lines or 1α-hydroxylase activity in a myelomonocytic cell line. The patient's course suggests that the abnormal 1,25(OH)2D and phosphorus metabolism is due to a tumor product that may be acting via stimulation of adenylate cyclase activity. Increased bone resorption prior to surgical resection suggests that the tumor may also produce an osteoclast activator. The rise in resorption surface and pyridinium cross-link excretion, increase in serum osteocalcin and bone mineralization, normalization of osteoid width, and fall in cancellous bone volume after resection are consistent with healing of osteomalacia by rapid remodeling.
Normal Human Cementum-Derived Cells: Isolation, Clonal Expansion, and In Vitro and In Vivo Characterization
Authors: Grzesik Wojciech J. , Kuzentsov Sergei A. , Uzawa Katsuhiro , Mankani Mahesh , Robey Pamela Gehron , Yamauchi Mitsuo
Published: April 2006

Cultures of primary human cementum-derived cells (HCDCs) were established from healthy premolar teeth extracted for orthodontic reasons. Cementum was manually dissected, fragmented, and digested twice with collagenase. Following a thorough wash to remove liberated cells, the remaining cementum fragments were plated in Dulbecco's modified Eagle's medium/F12 medium containing 10% fetal bovine serum. Discrete colonies that contained cells exhibiting fibroblast-like morphology were visible after 14–21 days of culture. When the colonies became sufficiently large, cells from individual colonies were isolated and subcultured. Cementum-derived cells exhibited low levels or no alkaline phosphatase activity and mineralized in vitro to a lesser degree than human periodontal ligament (PDL) cells and human bone marrow stromal cell (BMSC) cultures. To study differentiation capacities of HCDCs, cells were attached to hydroxyapatite/tricalcium phosphate ceramic and transplanted subcutaneously into immunodeficient mice. The transplants were harvested 3, 6, and 8 weeks after transplantation and evaluated histologically. In human BMSC transplants, new bone tissue was formed with a prominent osteoblastic layer and osteocytes embedded in mineralized bone matrix. No osseous tissue was formed by PDL cells. Of six single colony-derived strains of HCDCs tested, three formed a bone-like tissue that featured osteocyte/cementocyte-like cells embedded within a mineralized matrix and which was lined with a layer of cells, although they were somewhat more elongated than osteoblasts. These results show that cells from normal human cementum can be isolated and expanded in vitro. Furthermore, these cells are capable of differentiating and forming mineralized tissue when transplanted into immunodeficient mice.
Vis-à-Vis Cells and the Priming of Bone Formation
Authors: Riminucci Mara , Bradbeer Jeremy N. , Corsi Alessandro , Gentili Chiara , Descalzi Fiorella , Cancedda Ranieri , Dr. Bianco Paolo
Published: April 2006

Bone formation throughout skeletal growth and remodeling always entails deposition of new bone onto a pre-existing mineralized surface. In contrast, the initial deposition of bone in development requires the formation, ex novo, of the first mineralized structure in a nonmineralized tissue. We investigated the cellular events associated with this initial bone formation, with specific reference to the respective role of cartilage and bone cells in bones which form via a cartilage model. The cellular architecture of initial osteogenic sites was investigated by light, confocal, and electron microscopy (EM) in the membranous ossification of fetal calvarial bones (not forming via a cartilage model) and in the membranous ossification of the bony collars of endochondral bones. Bone sialoprotein (BSP), which is expressed during early phases of bone deposition and has been proposed to be involved in the control of both mineral formation and bone cell–matrix interactions, was used as a marker of initial bone formation. We found that at all sites, BSP-producing cells (as identified by intracellular immunoreactivity) are arranged in a characteristic vis-à-vis (face to face) pattern prior to the appearance of the first mineralizing BSP-immunoreactive extracellular matrix. In perichondral osteogenesis, the vis-à-vis pattern comprises osteoblasts differentiating from the perichondrium/periosteum and early hypertrophic chondrocytes located at the lateral aspects of the rudiment. By EM, the first mineral and the first BSP-immunoreactive sites coincide temporally and spatially in the extracellular matrix at the boundary between cartilage and periosteum. We further showed that in an in vitro avian model of chondrocyte differentiation in vitro to osteoblast-like cells, early hypertrophic chondrocytes replated as adherent cells turned on the expression of high levels of BSP in conjunction with the switch to collagen type I synthesis and matrix mineralization. We propose a model for the priming of bone deposition, i.e., the formation of the first bone structure, in which the architectural layout of cells competent to deposit a mineralizing matrix (the vis-à-vis pattern) determines the polarized deposition of bone. For bones forming via a cartilage model, the priming of bone deposition involves and requires cells that differentiate from early hypertrophic chondrocytes.
Bone Mass in Middle-Aged Osteoporotic Men and Their Relatives: Familial Effect
Authors: Cohen-Solal M. E. , Baudoin C. , Omouri M. , Kuntz D. , Prof. de Vernejoul M. C.
Published: April 2006

Severe idiopathic osteoporosis in middle-aged men is still poorly understood. The aim of this study was to assess the contribution of genetic factors in these patients. We studied 38 men (mean age ± SD, 50 ± 11 years) presenting with vertebral or peripheral bone fractures due to primary osteoporosis and 73 of their relatives divided into four subgroups: 19 brothers, 22 sisters, 13 sons, and 19 daughters. The control group comprised 199 age-matched subjects. In all subjects, we measured bone mineral density (BMD) and calculated the Z score at the lumbar spine (LS) and femoral neck (FN) based on the fitted BMD value in the controls. LS BMD values were lower in each of the four subgroups compared with the age-matched controls. The mean Z score for the overall group of 73 relatives was decreased compared with the age-matched controls (−1.28 ± 1.48 at the LS and −1.03 ± 1.19 at the FN) and was not influenced by gender or by whether the relatives were siblings or children. An LS Z score < −1) was found in 54.8% of the relatives of osteoporotic patients versus 17.4% of the control subjects (risk ratio, 3.2). Alcohol and tobacco abuse are well-known risk factors for osteoporosis in men. Among the 38 osteoporotic patients, 7 were heavy smokers (>20 pack-years), 8 were both heavy smokers and drinkers (>80 g/day for at least 10 years and γGT > 40 UI/l), and 23 had neither of these risk factors. BMD, Z score, and anthropometric data were the same in patients with and without risk factors. Decreases in LS and FN Z scores were similar in relatives of patients with and without risk factors. In conclusion, low BMD is observed in relatives of osteoporotic men with or without risk factors for osteoporosis, indicating that familial factors contribute to primary osteoporosis in middle-aged men.
Human Trabecular Bone Cells Are Able to Express Both Osteoblastic and Adipocytic Phenotype: Implications for Osteopenic Disorders
Authors: Nuttall Mark E. , Patton Amanda J. , Olivera Diane L. , Nadeau Daniel P. , Gowen Maxine
Published: April 2006

The decrease in bone volume associated with osteoporosis and age-related osteopenia is accompanied by increased marrow adipose tissue formation. Reversal of this process may provide a novel therapeutic approach for osteopenic disorders. We have shown that cells cultured from human trabecular bone are not only osteogenic, but are able also to undergo adipocyte differentiation under defined culture conditions. Osteoblast differentiation was induced by 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) and adipocyte differentiation by dexamethasone (dex) plus 3-isobutyl-1-methylxanthine (IBMX) treatment. Adipogenesis was characterized by lineage-specific enzyme and gene activities, α-glycerophosphate-3-dehydrogenase activity, fatty acid binding protein, aP2 and lipoprotein lipase expression. Osteoblastogenesis was assessed by osteoblast characteristic 1,25(OH)2D3 induction of alkaline phosphatase activity and osteoblast-specific 1,25(OH)2D3-induced osteocalcin synthesis and release. We provide evidence for a common pluripotent mesenchymal stem cell that is able either to undergo adipogenesis or osteoblastogenesis, using clonal cell lines derived from human trabecular bone cell cultures. Adipogenesis can be induced also by long chain fatty acids and the thiazolidinedione troglitazone. Dex plus IBMX-induced adipogenesis can be inhibited by interleukin-1β, tumor necrosis factor-α, and transforming growth factor-β. Interestingly, and in contrast to extramedullary adipocyte differentiation as shown by mouse 3T3L-1 and a human liposarcoma SW872 cell line, trabecular bone adipogenesis was unaffected by insulin. Also, the formation of fully differentiated adipocytes from trabecular bone cells after troglitazone treatment and long chain fatty acids was dependent on increased expression of the nuclear hormone receptor peroxisome proliferator-activated receptor γ2 caused by dex plus IBMX. Specific inhibition of marrow adipogenesis and promotion of osteoblastogenesis of a common precursor cell may provide a novel therapeutic approach to the treatment of osteopenic disorders.