bluuebunny/crossref_metadata_2025 huggingface dataset:
Preparation and Solvation Properties of Some Variable Charge Montmorillonites
Authors: Brindley G. W. , Ertem Gözen
Published: August 2006

Li-, Na-, K- and Ca-saturated Wyoming montmorillonites have been prepared and used to obtain Li,Na-, Li,K-, and Li,Ca-montmorillonites with a range of Li contents. These were heated at 220°C for 24 hr, causing the Li+ ions to migrate mainly into the layer structure and leaving varying amounts of Li+, Na+, K+, and Ca2+ ions in the interlayer positions as determined by exchange with NH4+ ions. The results are only partially consistent with a migration of the Li+ ions into vacant octahedral sites up to the limit of the octahedral layer charge. Solvation of the resulting clays with water and various organic liquids showed the following results: With water, acetone and 3-pentanone, expansion of the montmorillonites increased in a step-wise manner with increasing numbers of interlayer cations qualitatively in accord with the field strength of the cations and the dipole moments of the molecules. With ethanol, ethylene glycol and morpholine, swelling with each liquid was practically independent of the number of interlayer cations, within the limits of the prepared materials. It is suggested that for the second group of liquids some mechanism additional to cation-dipole interactions, such as hydrogen bonding to silicate oxygen surfaces, may play an important part.
Effects of Octahedral-Iron Reduction and Swelling Pressure on Interlayer Distances in Na-Nontronite
Authors: Wu Jun , Low P. F. , Roth C. B.
Published: August 2006

A new type of environmental chamber for X-ray diffraction was designed that could sustain elevated, internal pressures of nitrogen or any other gas under oxygen-free conditions and that allowed the positions of the specimen and edge aperture to be adjusted by remote control. It was used to determine the values of the interlayer spacing, λ, of nontronite from Garfield, Washington, in different stages of reduction at different values of Π, the swelling pressure of the nontronite. At equilibrium, Π was equal to the pressure under which water was expressed from the clay. Both partially and fully expanded layers were found to exist in the reduced nontronite, the fraction of partially expanded layers increasing with increasing Π and Fe2+/Fe3+, the ratio of Fe2+ to Fe3+ in octahedral sites. Also, λ for the partially expanded layers was found to depend on Fe2+/Fe3+ but not on Π, and λ for the fully expanded layers was found to depend on Π but not on Fe2+/Fe3+. These findings were interpreted to mean that the reduction of Fe affected the short-range interlayer forces, but not the long-range ones.
Clay-Organic Complexes as a Cementing Agent in the Arahama Sand Dune, Japan
Authors: Tazaki Kazue , Kimura S. , Yoshimura T. , Akai J. , Fyfe W. S.
Published: August 2006

Cementing materials in the Arahama sand dune, Japan, were studied mineralogically and biogeochemically to gain a better understanding of the cause of hardening. The cementing material is a clay-organic complex composed of noncrystalline gels and a matrix of small, poorly crystalline particles showing 14–16-Å spacings. The gel materials appear to have transformed into the poorly crystalline particles, which have a high carbon content and Al/Si ratios of 2.2 to 2.0. These particles are slightly richer in Si and poorer in Fe than the gel materials themselves. The organic portion of the complex can be removed by H2O2 treatment, leaving a noncrystalline network-structure containing a dispersed granular component. Scanning auger-depth profiles of individual particles show a high surface concentration of C and O and an increase in the Al/Si ratio with depth. The energy-intensity distribution suggests a mixture of carbon compounds having a major core-line binding energy of a hydrocarbon. The gel-cementing materials in the sand dune may have been formed from biochemical weathering products of organic matter, which subsequently controlled the formation of clay-organic complexes.
Phillipsite from Silicic Tuffs in Saline, Alkaline-Lake Deposits
Authors: Sheppard Richard A. , Fitzpatrick Joan J.
Published: August 2006

Phillipsite is a common constituent in diagenetically altered rhyolitic vitric tuffs of Cenozoic saline, alkaline-lake deposits where it occurs as spherulites or aggregates of prismatic crystals. This phillipsite has chemical and physical properties that differ from phillipsites that occur in rocks of other compositions and depositional environments, but previously it had not been completely characterized. Published analyses of five samples from four deposits in the southwestern United States show that the phillipsite is very siliceous and alkalic; the Si/(Al + Fe3+) ratio is 3.08–3.37, alkalis greatly exceed the divalent exchangeable cations, and the Na/K ratio is 1.05–3.05. The mean index of refraction (1.451–1.470) is much lower than that generally reported for the phillipsite group and can be correlated with the relatively high Si and alkali contents. Monoclinic unit-cell parameters show the following ranges: a = 9.931–9.991 Å, b = 14.142–14.155 Å, c = 8.650–8.706 Å, ß = 124.57–125.07°, and V = 1000.3–1007.4 Å3. The especially small b dimension is consistent with the high Si content.
Rheological Properties of Organophilic Synthetic Hectorites and Saponites
Authors: Iwasaki Takashi , Onodera Yoshio , Torii Kazuo
Published: August 2006

To determine the dependency of rheological properties on mineralogical characteristics, eleven organophilic hectorite and nine organophilic saponite samples were prepared from hydrothermally synthesized smectites and a quaternary ammonium salt containing mainly octadecyl groups as alkyl chains and were examined by X-ray powder diffraction (XRD), particle size, chemical, and rheological procedures. The rheological properties of the organophilic products dispersed in toluene were found to depend chiefly on (1) particle size, (2) the expansion behavior of the stacked clay platelets, in which the amount and location of negative charge of the silicate layer affected the expandability, and (3) the amount of methanol added as a polar activator. By the addition of 2–4% methanol, apparent viscosities of the hectorite clays were drastically increased at low shear rate, although even a 10% addition did not significantly affect the saponite clays. Under the most suitable gellation conditions, the saponite clays showed lower apparent viscosity than the hectorite clays. Inasmuch as the former had its negative charge near the surface of the silicate layer and formed strong bonds to the organic ion, the expansion of the platelets was apparently difficult. An optimum layer charge for increasing the viscosity was found; specifically 0.45–0.50 and 0.50–0.55 equivalents per half unit cell for saponite and hectorite clays, respectively. Because the saponite clays contained a denser population of organic ions than the hectorite clays, the ion density in the interlayer of both clays was considered to be the same, i.e., about 0.4 organic ions per unit ab area.
“Chloritized” Vermiculite in a Korean Ultisol Studied by Ultramicrotomy and Transmission Electron Microscopy
Authors: Wada Koji , Kakuto Yasuko
Published: August 2006

“Chloritized” vermiculite coexisting with kaolin-group minerals, vermiculite, mica, and gibbsite in the 0.2–0.5-µM fraction separated from a Korean Ultisol was studied by ultramicrotomy and high-resolution electron microscopy. The (001) lattice images observed from thin sections showed that the “chloritized” vermiculite was composed of particles which differed in their shape and the stacking of silicate layers. On saturation with K+, the silicate layers had spacings of 14–10 Å, with 14–12-Å layers being dominant. The 8–7-Å layers of a few particles appeared to be segregated close to the basal plane surfaces, but not necessarily close to the edge surfaces. The silicate layers were more or less curved and wavy and were commonly discontinuous. They formed packets (100–500 Å thick) by stacking, which were associated “face-to-face” and/or “edge-to-edge” or stacked parallel or subparallel to form particles of different shapes. The extent of interlayer collapse of the 14-Å layers on heating differed from one particle to the other, but was fairly uniform within a particle. Treatment with hot 1/3 M sodium citrate dissolved the interlayer material and possibly the material present between the packets from the “chloritized” vermiculite and from a few fine plates of kaolin-group minerals. The interlayer material and its chemical composition, therefore, could not be determined.
X-Ray Photoelectron Spectroscopic Study of Cobalt(II) and Nickel(II) Sorbed on Hectorite and Montmorillonite
Authors: Davison Nigel , McWhinnie William R. , Hooper Alan
Published: August 2006

The safe disposal of 60Co, 63Ni, and 59Ni has required considerable information on the interactions of Co2+ and Ni2+ with clay minerals in the geosphere. X-ray photoelectron spectroscopy (XPS) has been used to probe the sorption sites for Co2+ and Ni2+ on hectorite and montmorillonite. The spectra were measured for Co-hectorite, Ni-hectorite, and Ni-montmorillonite immediately following ion exchange and after washing the clay two and five times with distilled water. The spectra, recorded following etching of the surface with an argon ion beam, differentiate two sorption sites; a labile (to washing) fraction sorbed as ion pairs, and a non-labile fraction sorbed by ion exchange at broken bond and interlamellar sites. The data were consistent with the sorption of metal ions (Co2+, Ni2+) in a common “MO6” ligand environment.

Co2+ had a greater affinity for exchange on hectorite than did Ni2+; but Ni2+ had a greater affinity for the surface of montmorillonite than for hectorite. The argon ion etching of Ni-montmorillonite gave rise to a new photopeak of 853 eV, which was probably due to elemental Ni formed consequent to the chemical violation of the surface by ion etching.
Influence of Citrate on the Kinetics of Fe(II) Oxidation and the Formation of Iron Oxyhydroxides
Authors: Krishnamurti G. S. R. , Huang P. M.
Published: August 2006

The rate of Fe(II) oxidation at a constant rate of oxygen supply in the presence of citrate was measured at pH 6.0 at various citrate/Fe(II) molar ratios at 23.5°C in 0.01 M ferrous Perchlorate system. The kinetics followed a first-order reaction with respect to Fe(II) concentration at constant pH (6.0) and aeration (5 ml/min). The rate constant decreased exponentially from 41.3 × 10-4 to 7.6 × 10-4/min with an increase in the citrate/Fe(II) molar ratio from 0 to 0.1.

The nature of the hydrolytic products formed after 120 min of oxidation was arrived at by X-ray powder diffraction (XRD), infrared spectrometry (IR), and transmission electron microscopic (TEM) analyses. In the absence of citrate, goethite (α-FeOOH) and poorly crystalline lepidocrocite (γ-FeOOH) were the oxidation products formed at pH 6.0. The formation of lepidocrocite was promoted at the expense of goethite at citrate/Fe(II) molar ratios of 0.0005 to 0.005. The formation of lepidocrocite was especially pronounced at a citrate/Fe(II) molar ratio of 0.001, as observed from the width at half height (WHH) and the area of the 020 XRD peak of lepidocrocite. At a citrate/Fe(II) molar ratio of 0.01, however, the crystallization was perturbed resulting in the formation of noncrystalline Fe oxides, and no precipitate was observed at a citrate/Fe molar ratio of 0.1. The strong complexation of Fe(II) with citrate retarded the kinetics of Fe(II) oxidation and the formation and hydrolysis of Fe(III). The complexation, electrostatic, and steric effects of the coexisting citrate anions in solution apparently influenced the oxygen coordination and the way by which the double rows of edge-sharing Fe(O,OH)6 octahedra linked during crystallization, resulting in the formation of lepidocrocite.
Interaction of the Herbicide Acifluorfen with Montmorillonite: Formation of Insoluble Fe3+, Al3+, Cu2+, and Ca2+ Complexes
Authors: Pusino A. , Micera G. , Gessa C.
Published: August 2006

Analytical, spectroscopic, and X-ray powder diffraction techniques were used to investigate the adsorption of the herbicide sodium acifluorfen (acifluorfen = 5-[2-chloro-4-(trifluorornethyl)phenoxy]-2-nitrobenzoic acid) from aqueous solution onto Cu2+-, Al3+-, Fe3+-, and Ca2+-saturated montmorillonite. As indicated by infrared and electron spin resonance spectra, which are coincident with those of the corresponding solid metal complexes, and by the basal spacings, which are the same for all the samples, acifluorfen extracted the exchangeable ions from the clay interlayer and precipitated them on external surfaces. The process involved the replacement of sodium as the saturating ion and was due to the formation of insoluble complexes between the herbicide and polyvalent metal ions.
Bond Energy of Adsorbed and Interlayer Water: Kerolite Dehydration at Elevated Pressures
Authors: Miller Anna Kokines , Guggenheim Stephen , van Groos August F. Koster
Published: August 2006

The dehydration reaction of kerolite was investigated using high-pressure differential thermal analysis at pressures as high as 600 bars. The peak associated with the dehydration is broad, suggesting the presence of a series of overlapping reactions ranging from the release of adsorbed water to interlayer water. The peak temperature is 136°C at 1.8 bars and increases to 516°C at 586 bars. The primary reaction represents loss of adsorbed water having a bond energy of 1.5 ± 1 kJ/mole. A small amount of water may be present as interlayer water and has a bond energy of 7.5 ± 3 kJ/mole.
Effect of Na-Hexametaphosphate on the Hydraulic Conductivity of Kaolinite-Sand Mixtures
Authors: Levy G. J. , Shainberg I. , Alperovitch N. , van der Merwe A. J.
Published: August 2006

Mixtures of kaolinite clay and quartz sand were packed in columns and leached with NaCl-CaCl2 solutions of different concentrations (ranging from 0.5 M to distilled water) having sodium adsorption ratios (SAR) of 5, 10 and 20. Sodium hexametaphosphate (NaHMP) (10 g/m3) was added to each solution. Changes in the hydraulic conductivity (HC) and clay concentration in the effluent were measured, and the dispersion of the clay was evaluated. In the absence of NaHMP, using distilled water instead of 0.01 M solutions caused some reduction in the HC; the reduction became more severe as the SAR increased. At SAR 20 the HC dropped to 73% of that obtained when the 0.5 M salt solution was used. This reduction in HC was related to increases in the pH of the effluent and partial dispersion of the clay. On adding the NaHMP to the leaching solutions, a marked decrease in the HC and severe clay dispersion were observed at all SAR levels, if the kaolinite-sand mixtures were leached with dilute solutions and distilled water. The HC dropped to 40% of that obtained when leaching with 0.5 M salt solution, and dispersed clay in the effluent peaked at about 1% in the SAR 20 treatment following leaching with distilled water. The observed reduction in the HC of the kaolinite-sand mixture when NaHMP was added to the leaching solutions was due to the dispersive effect of NaHMP and sodium on the kaolinite. The polyanion NaHMP reduced the edge-to-face particle interactions, thereby enabling the dimise double-layer repulsion forces to predominate. Following addition of the polyphosphate, the response of kaolinite to sodium and electrolyte concentration was similar to that reported in the literature for smectite.
Effects of Iron Oxidation State on the Texture and Structural Order of Na-Nontronite Gels
Authors: Stucki Joseph W. , Tessier Daniel
Published: August 2006

Aqueous gels of unaltered (oxidized) and chemically reduced ferruginous smectite (SWa-1 from the Source Clays Repository of The Clay Minerals Society) were characterized by transmission electron microscopy, electron diffraction, and energy-dispersive X-ray fluorescence to establish details regarding their texture, inter-layer and inter-particle arrangements, and chemical composition. Micrographs revealed that the reduction of structural Fe(III) to Fe(II) caused a consolidation of smectite particles from an extensive network of small crystals (1–6 layers thick) to distinct particles of limited size in the a-b direction and about 20–40 layers thick. The interlayer distances in the reduced sample appeared to be more uniform than in the oxidized sample, but both exhibited spacings of about 12.6 A. Chemical analysis showed no qualitative differences as a result of oxidation state. Electron diffraction patterns displayed marked differences. The pattern of the oxidized sample consisted of homogeneous rings, indicating that the stacking order in the a-b plane was turbostratic or disordered, whereas the reduced pattern exhibited much more order as evidenced by distinct spots amid low-intensity rings, suggesting that inter-layer attractive forces were stronger if Fe(II) was present in the clay crystal.
Dehydration and Rehydration of Saponite and Vermiculite
Authors: Kawano Motoharu , Tomita Katsutoshi
Published: August 2006

The rehydration properties and behavior of interlayer cations of Ca-, Mg-, Na-, and K-saturated homoionic saponite and vermiculite heated at various temperatures were examined and their rehydration mechanisms elucidated. The most notable features of saponite were (1) except for the Mg-saturated specimen, all saponite samples rehydrated until the crystal structure was destroyed by heating; (2) the rehydration rate in air after heating decreased in the order: K+ > Na+ > Ca2+ > Mg2+; (3) the interlayer cations apparently migrated into hexagonal holes of the SiO4 network on thermal dehydration; and (4) the b-parameter expanded on thermal dehydration. The rehydration properties and behavior of interlayer cations of vermiculite were: (1) except for the K-saturated specimen, all vermiculite samples rehydrated until the crystal structure was destroyed by heating; (2) the rehydration rate in air after heating decreased in the order: Mg2+ > Ca2+ > Na+ > K+; (3) the interlayer cations apparently did not migrate into the hexagonal holes, but remained at the center of the interlayer space, even after thermal dehydration; and (4) except for the K-saturated specimen, the 6-parameters of the samples contracted on thermal dehydration. The different rehydration properties of saponite and vermiculite were apparently due to the behavior of the interlayer cations during thermal dehydration. For rehydration to occur, the interlayer cations of saponite had to migrate out of the hexagonal holes. Consequently, saponite saturated with a large cation rehydrated rapidly, whereas saponite saturated with a small cation rehydrated slowly. On the other hand, the interlayer cations of vermiculite remained in the interlayer space; therefore, the rehydration properties of vermiculite were strongly affected by the hydration energies of the interlayer cations. Furthermore, electron diffraction patterns suggested that the saponite and vermiculite consisted of random stacking and ordered stacking of adjacent 2:1 layers, respectively. The nature of the stacking of the minerals seemed to be the most important factor controlling the behavior of interlayer cations in the thermal dehydration process.
Practical Notes Concerning the Indexing of X-Ray Powder Diffraction Patterns of Clay Minerals
Authors: Bailey S. W.
Published: August 2006

Hydrous phyllosilicate minerals exhibit many variations in unit-cell shape and symmetry, distortion due to cation ordering, polytypic repeats along Z, and lateral modulations that can affect the ease of indexing of X-ray powder diffraction patterns. In indexing the patterns of monoclinic and triclinic hydrous phyllosilicates it is important that the indices of all overlapping but nonequivalent lines be listed and used in the indexing program, with weights assigned according to their multiplicities. Deviations from orthogonal unit-cell geometry show up by a broadening or a splitting of nearly superimposed lines, as occurs also if the observed ß angle differs from that produced by a layer shift of ideal magnitude (e.g., a/3). Observed powder intensities should be correlated with those expected from the structure, and an index should not be assigned solely on the basis of the calculated d-value that is closest to that observed. Assigned indices should not violate space group extinctions. Multilayer structures show up in reflections of type k ≠ 3n for C-centered unit cells, not in 00/reflections.
Evolution of the Porous Structure and Surface Area of Palygorskite Under Vacuum Thermal Treatment
Authors: Cases J. M. , Grillet Y. , François M. , Michot L. , Villiéras F. , Yvon J.
Published: August 2006

The modification of the external surface area and the two types of microporosity of palygorskite (structural and interfiber porosity) were examined as a function of the temperature of a vacuum thermal treatment to 500°C. The methods used included: controlled-transformation-rate thermal analysis, N2 and Ar low-temperature adsorption microcalorimetry, conventional and continuous gas-adsorption volumetry (for N2 and Ar) at 77 K and CO2 at 273 and 293 K, water vapor adsorption gravimetry, and immersion microcalorimetry in water. At temperatures < 100°C only 18% of the structural microporosity was available to N2, 13% to Ar, and 100% to CO2 at 273 K. In both experiments the channels filled at very low relative pressures. At temperatures between 70° and 130°C the structure folded, and the mineral transformed to anhydrous palygorskite, which showed no structural microporosity. The interfiber microporosity was found to be independent of the temperature treatment, and the external surface area decreased slightly from 65 to 54 m2/g. The water adsorption isotherms showed that the folding of the structure was reversible up to final outgassing temperatures >225°C.
Catalysis of Nontronite in Phenols and Glycine Transformations
Authors: Wang M. C.
Published: August 2006

The catalytic power of Ca-nontronite (0.2–2μm) for the polycondensation of phenols and glycine and the associated reactions that involve the ring cleavage of phenols and the decarboxylation and deamination of glycine was studied in systems free of microbial activity. At the end of a 90-hr reaction period, the amount of CO2released from the Ca-nontronite-glycine-pyrogallol, Ca-nontronite-glycine-eatechol, and Ca-nontronite-glycine-hydroquinone systems were 5.1, 8.7, and 11.6 times higher, respectively, than those from the respective nontronite-free systems, showing the catalytic role of Ca-nontronite in the ring cleavage of phenols and the decarboxylation of glycine. The release of CO2and NH3from the Ca-nontronite-glycine system revealed that Ca-nontronite can catalyze decarboxylation and deamination of glycine. The ability of Ca-nontronite to catalyze the deamination of glycine was substantially enhanced by the presence of a phenol. The visible absorbances at both 472 and 664 nm of the supernatants, the total yields of N-containing humic polymers, and the fractions of glycine converted to nitrogenous polymers indicated that polycondensation of glycine and phenol was greatly catalyzed by Ca-nontronite. The total N-containing humic polymers formed in the systems decreased in the order: Ca-nontronite-glycine-pyrogallol > Ca-nontronite-glycine-cateehol > Ca-nontronite-glycine-hydroquinone > glycine-pyrogallol > glycine-hydroquinone > glycine-catechol. The infrared and electron spin resonance spectra of humic acid (HA) and fulvic acid (FA) formed in the supernatants of the reaction systems were quite similar to those of soil HA and FA. The catalytic power of Ca-nontronite in affecting the ring cleavage of phenols, deamination and decarboxylation of amino acids, and formation of humic substances derived from phenols with amino acids in soils and the related environments thus merits attention.
High-Charge Smectite in Spanish “Raña” Soils
Authors: Aragoneses Francisco José , García-González Maria Teresa
Published: August 2006

In a study of “rana” soils of central Spain, hydroxy-interlayered 2:1 clay minerals were identified in the upper horizons and high-charge smectite in the lower horizons, with kaolinite the most abundant phyllosilicate. The high-charge smectite showed a basal spacing of 18 Å on Mg-saturation and glycerol solvation and 10 Å on K-saturation and air-drying. It is concentrated in the coarse fractions and appears to be basically a beidellite in the fine-silt fractions and a montmorillonite in the clay fractions. Pre-existing illite was probably transformed into hydroxy-interlayered 2:1 clays in the surface horizons, whereas high-charge smectite formed in the deeper horizons. These minerals, which were apparently not stable in the existing soil conditions, were the first stage in the degradation process of illite. The stable mineral in these soil profiles was kaolinite.
Association Between Bone Mass and Fractures in Children: A Prospective Cohort Study
Authors: Clark Emma M , Ness Andy R , Bishop Nicholas J , Tobias Jon H
Published: August 2006

This is the first prospective cohort study of the association between bone mass and fracture risk in childhood. A total of 6213 children 9.9 years of age were followed for 24 months. Results showed an 89% increased risk of fracture per SD decrease in size-adjusted BMC.

Introduction: Although previous case-control studies have reported that fracture risk in childhood is inversely related to bone mass, this has not been confirmed in prospective studies. Additionally, it remains unclear which constituent(s) of bone mass underlie this association. We carried out a prospective cohort study to examine the relationship between DXA measures in children 9.9 years of age and risk of fracture over the following 2 years.

Materials and Methods: Total body DXA scan results obtained at 9.9 years of age were linked to reported fractures over the following 2 years in children from a large birth cohort in southwest England. DXA measures consisted of total body less head (TBLH) BMD, bone area, and BMC, and results of subregional analysis of the humerus. Analyses were adjusted for age, sex, ethnicity, and social position.

Results: Complete data were available on 6213 children. There was a weak inverse relationship between BMD at 9.9 years and subsequent fracture risk (OR per SD decrease = 1.12; 95% CI, 1.02–1.25). In analyses examining the relationship between fracture risk and volumetric BMD, fracture risk was inversely related to BMC adjusted for bone area, height, and weight (OR = 1.89; 95% CI, 1.18–3.04) and to estimated volumetric BMD of the humerus (OR = 1.29; 95% CI, 1.14–1.45). Fracture risk was unrelated to both TBLH and humeral bone area. However, in analyses of the relationship between fracture risk and bone size relative to body size, an inverse association was observed between fracture risk and TBLH area adjusted for height and weight (OR = 1.51; 95% CI, 1.17–1.95).

Conclusions: Fracture risk in childhood is related to volumetric BMD, reflecting an influence of determinants of volumetric BMD such as cortical thickness on skeletal fragility. Although bone size per se was not related to fracture risk, we found that children who fracture tend to have a smaller skeleton relative to their overall body size.
Quantitative Trait Loci for BMD Identified by Autosome-Wide Linkage Scan to Chromosomes 7q and 21q in Men from the Amish Family Osteoporosis Study
Authors: Streeten Elizabeth A , McBride Daniel J , Pollin Toni I , Ryan Kathy , Shapiro Jay , Ott Sandy , Mitchell Braxton D , Shuldiner Alan R , O'Connell Jeffery R
Published: August 2006

Using autosome-wide linkage analysis in 964 Amish, strong evidence was found for the presence of genes affecting hip and spine BMD in men on chromosomes 7q31 and 21q22 (LOD = 4.15 and 3.36, respectively).

Introduction: BMD is highly heritable, with genetic factors accounting for 60–88% of variation. The goal of this study was to localize genes contributing to BMD variation.

Materials and Methods: The Amish Family Osteoporosis Study was designed to identify genes affecting bone health. The Amish are a genetically closed population with a homogeneous lifestyle. BMD was measured at the spine, hip, and radius using DXA in 964 participants (mean age, 50.2 ± 16.3 [SD] years; range, 18–99 years) from large multigenerational families. Genotyping of 731 highly polymorphic microsatellite markers (average spacing of 5.4 cM) and autosome-wide multipoint linkage analysis were performed.

Results: In the overall study population, no strong evidence for linkage was detected to any chromosomal region (peak LOD: 2.11 for radius BMD on chromosome 3q26). In a subgroup analysis of men (n = 371), strong evidence was detected for a quantitative trait locus (QTL) influencing BMD variation on chromosome 7q31 at the total hip (LOD = 4.15) and femoral neck (LOD = 3.09) and for a second QTL influencing spine BMD at 21q22 (LOD = 3.36). Suggestive evidence of linkage was found in men for a QTL at 12q24 affecting total hip BMD (LOD = 2.60) and at 18p11 for femoral neck (LOD = 2.07), and in women (n = 593) at 1p36 for femoral neck BMD (LOD = 2.02) and at 1q21 for spine BMD (LOD = 2.11). In age subgroup analyses, suggestive evidence for linkage was found for those <50 years of age (n = 521) on chromosomes 11q22 and 14q23 (LODs = 2.11 and 2.16, respectively) and for those >50 years of age (n = 443) on 3p25.2 (LOD = 2.32).

Conclusions: These results strongly suggest the presence of genes affecting hip and spine BMD in men on chromosomes 7q31 and 21q22. Modest evidence was found for genes affecting BMD in women on chromosomes 1p36 and 1q21 and in men at 12q24, replicating results from other populations.
RANK Expression as a Cell Surface Marker of Human Osteoclast Precursors in Peripheral Blood, Bone Marrow, and Giant Cell Tumors of Bone
Authors: Atkins Gerald J , Kostakis Panagiota , Vincent Cristina , Farrugia Amanda N , Houchins Jeffrey P , Findlay David M , Evdokiou Andreas , Zannettino Andrew CW
Published: August 2006

RANK expression in vivo on hematopoietic subsets including pre-osteoclasts, identified by monoclonal antibodies, has not been described. We describe the lineages that express RANK in bone marrow, peripheral blood, and GCTs. We show that CD14+RANKhigh cells constitute a circulating pre-osteoclast pool.

Introduction: The expression of RANK by subsets of hematopoietic cells has not been adequately studied in humans. While attributed to the monocytoid lineage, the phenotype of the pre-osteoclast (pre-OC) with respect to RANK expression in vivo remains unclear. We tested monoclonal antibodies (MAbs) raised against the extracellular domain of recombinant human RANK for reactivity with normal peripheral blood (PB) and bone marrow (BM) mononuclear cells (PBMNCs and BMMNCs, respectively). We also tested reactivity with giant cell tumor cells (GCT), a confirmed source of pre-OC and mature OCs.

Materials and Methods: Human PBMNCs, BMMNCs, and GCT cells were analyzed for reactivity with anti-RANK MAbs by flow cytometry in combination with hematopoietic lineage restricted markers. GCTs were also analyzed by immunofluorescence. CD14+ monocytoid cells were sorted by fluorescence-activated cell sorting (FACS) based on their relative RANK expression and cultured under OC-forming conditions.

Results: RANK+ cells were detected similarly by three independent anti-RANK MAbs. One MAb (80736) immunoprecipitated RANK–RANKL complexes from surface-biotinylated GCT lysates. Using dual-color flow cytometry, RANK was detected on CD14+ (monocytoid), CD19+ (B-lymphoid), CD56+ (NK cell), and glycophorin A+ erythroid progenitors. Minor populations of both CD3+ T lymphocytes and BM CD34+ hematopoietic progenitors also expressed cell surface RANK. In GCTs, RANK expression was identified on mononuclear CD45+CD14+αVβ3+c-Fms+ cells, likely to be committed pre-OC, and on multinucleated CD45+αVβ3+TRACP+ OCs. Importantly, sorted CD14+RANKhigh PBMNCs treated with recombinant RANKL and macrophage-colony stimulating factor (M-CSF) gave rise to approximately twice the number of osteoclasts than RANKmid or RANKlow cells.

Conclusions: These results suggest that committed monocytoid RANK+ pre-OCs are represented in the marrow and circulate in the periphery, forming a pool of cells capable of responding rapidly to RANKL. The ability to reliably detect committed pre-OC in peripheral blood could have important clinical applications in the management of diseases characterized by abnormal osteoclastic activity.
Association Between Serum 25(OH)D Concentrations and Bone Stress Fractures in Finnish Young Men
Authors: Ruohola Juha-Petri , Laaksi Ilkka , Ylikomi Timo , Haataja Riina , Mattila Ville M , Sahi Timo , Tuohimaa Pentti , Pihlajamäki Harri
Published: August 2006

Low vitamin D level may predict rickets, osteomalacia, or osteoporosis. We examined serum 25(OH)D concentration as a predisposing factor for bone stress fracture in 756 military recruits. The average serum 25(OH)D concentration was significantly lower in the group with fracture, suggesting a relationship between vitamin D and fatigue bone stress fracture.

Introduction: Low vitamin D level may predict rickets, osteomalacia, or osteoporosis. Fatigue bone stress fracture is one of the most frequently seen types of overuse injuries in athletes and military recruits. An association was recently shown between vitamin D and BMC. A correlation has also been found between low femoral BMD and stress fractures. We measured serum 25(OH)D concentration in a population sample of military recruits to determine if vitamin D is a predisposing factor for fatigue bone stress fracture.

Materials and Methods: We prospectively followed 800 randomly selected, healthy Finnish military recruits with a mean age of 19 years for developing stress fractures in homogenous circumstances. Blood for serum 25(OH)D concentration was drawn at entry into military service, and the weight, height, body mass index (BMI), muscle strength, and 12-minute running were measured for all subjects. Serum 25(OH)D concentrations were measured with enzyme immunoassay. At end of the 90-day follow-up, 756 subjects completed the study. Subjects without fracture constituted controls.

Results: Twenty-two recruits with stress fracture were identified (2.9%), the incidence being 11.6 (95% CI: 6.8–16.5) per 100 person-years. In the final multivariate analysis, the significant risk factor for stress fracture in conscripts was a below median serum 25(OH)D level (75.8 nM), OR being 3.6 (95% CI: 1.2–11.1). No significant associations between BMI (p = 0.255), age (p = 0.216), or smoking (p = 0.851) and bone stress fracture were found in this study population.

Conclusions: A lower level of serum 25(OH)D concentration may be a generally predisposing element for bone stress fractures. Considering the obvious need of additional vitamin D in prevention of stress fractures, the effects of vitamin D fortification of foods and supplementation will be subjects of interest for future research.
Intervertebral Disc Degeneration Can Predispose to Anterior Vertebral Fractures in the Thoracolumbar Spine
Authors: Adams Michael A , Pollintine Phillip , Tobias Jon H , Wakley Glenn K , Dolan Patricia
Published: August 2006

Mechanical experiments on cadaveric thoracolumbar spine specimens showed that intervertebral disc degeneration was associated with reduced loading of the anterior vertebral body in upright postures. Reduced load bearing corresponded to locally reduced BMD and inferior trabecular architecture as measured by histomorphometry. Flexed postures concentrated loading on the weakened anterior vertebral body, leading to compressive failure at reduced load.

Introduction: Osteoporotic fractures are usually attributed to age-related hormonal changes and inactivity. However, why should the anterior vertebral body be affected so often? We hypothesized that degenerative changes in the adjacent intervertebral discs can alter load bearing by the anterior vertebral body in a manner that makes it vulnerable to fracture.

Materials and Methods: Forty-one thoracolumbar spine “motion segments” (two vertebrae and the intervertebral disc) were obtained from cadavers 62–94 years of age. Specimens were loaded to simulate upright standing and flexed postures. A pressure transducer was used to measure the distribution of compressive “stress” inside the disc, and stress data were used to calculate how compressive loading was distributed between the anterior and posterior halves of the vertebral body and the neural arch. The compressive strength of each specimen was measured in flexed posture. Regional volumetric BMD and histomorphometric parameters were measured.

Results: In the upright posture, compressive load bearing by the neural arch increased with disc degeneration, averaging 63 ± 22% (SD) of applied load in specimens with severely degenerated discs. In these specimens, the anterior half of the vertebral body resisted only 10 ± 8%. The anterior third of the vertebral body had a 20% lower trabecular volume fraction, 16% fewer trabeculae, and 28% greater intertrabecular spacing compared with the posterior third (p < 0.001). In the flexed posture, flexion transferred 53–59% of compressive load bearing to the anterior half of the vertebral body, regardless of disc degeneration. Compressive strength measured in this posture was proportional to BMD in the anterior vertebral body (r2 = 0.51, p < 0.001) and inversely proportional to neural arch load bearing in the upright posture (r2 = 0.28, p < 0.001).

Conclusions: Disc degeneration transfers compressive load bearing from the anterior vertebral body to the neural arch in upright postures, reducing BMD and trabecular architecture anteriorly. This predisposes to anterior fracture when the spine is flexed.
TRACP Influences Th1 Pathways by Affecting Dendritic Cell Function
Authors: Esfandiari Ehsanollah , Bailey Michael , Stokes Christopher R , Cox Timothy M , Evans Martin J , Hayman Alison R
Published: August 2006

TRACP, a marker of osteoclasts, is also expressed by cells of the immune system. We identified a novel function for TRACP in the dendritic cell. DCs from TRACP knockout mice have impaired maturation and trigger reduced Th1 responses in vivo. We postulate that TRACP has an important role in the presentation of antigens to T cells.

Introduction: TRACP is highly expressed by osteoclasts, activated macrophages, and dendritic cells (DCs). Knockout mice lacking TRACP have an intrinsic defect in osteoclastic resorption and macrophages that display abnormal immunomodulatory responses and cytokine secretion profiles. Our aim in this study was to investigate the significance of TRACP in the inductive phase of the immune response by examining dendritic cells from TRACP−/− mice.

Materials and Methods: Maturational state and function of leukocyte subsets in mice was assessed by flow cytometry. The ability of the immune system to respond to nonspecific activation and to specific antigen was assessed by delayed type hypersensitivity and the presence of isotype-specific serum antibody in vivo and T-cell proliferation and cytokine production in vitro.

Results: The ability of lipopolysaccharide (LPS) to upregulate MHC II and CD80 in DCs from TRACP−/− mice was reduced compared with wildtype mice, although production of IL-10 by DCs from TRACP-deficient animals was increased. T- and B-cell responses not involving antigen presentation (anti-CD3, TNP-ficoll) were normal in TRACP−/− mice, but responses to T-dependent antigens were impaired. Specifically, TRACP−/− mice had defective delayed hypersensitivity responses to picryl chloride and reduced proliferative responses to ovalbumin compared with wildtype mice. In response to ovalbumin, but not anti-CD3, T cells from TRACP−/− mice produced less interferon-γ (IFN-γ), but there was no difference in IL-4 production: TRACP−/− mice also produced less ovalbumin (OVA)-specific IgG2a after immunization.

Conclusions: The finding that DCs from TRACP−/− mice have impaired maturation and defective Th1 responses shows that TRACP is important for polarizing responses in naïve T cells to antigen-presented dendritic cells.
Expression Profile of RhoGTPases and RhoGEFs During RANKL-Stimulated Osteoclastogenesis: Identification of Essential Genes in Osteoclasts
Authors: Brazier Hélène , Stephens Sébastien , Ory Stéphane , Fort Philippe , Morrison Nigel , Blangy Anne
Published: August 2006

RhoGTPases regulate actin cytoskeleton dynamics, a key element in osteoclast biology. We identified three novel genes induced during RANKL-stimulated osteoclastogenesis among RhoGTPases and their exchange factors that are essential in osteoclast biology.

Introduction: During the process of differentiation, adhesion to the bone matrix or osteolysis, the actin cytoskeleton of osteoclasts undergoes profound reorganization. RhoGTPases are key regulators of actin dynamics. They control cell adhesion, migration, and morphology through their action on actin cytoskeleton. In mice, there are 18 low molecular weight RhoGTPases. They are activated by guanine nucleotide exchange factors: the RhoGEFs. There are 76 RhoGEFs in mice: 65 belong to the Dbl family and 11 to the CZH family. To identify novel genes among RhoGTPases and RhoGEFs important in osteoclasts, we established the expression profiles of the complete families of RhoGTPases and RhoGEFs during RANKL-stimulated osteoclastogenesis.

Materials and Methods: The RAW264.7 cell line, mouse bone marrow macrophages, and hematopoietic stem cells were used as precursors for RANKL-induced osteoclastogenesis. Gene arrays and real-time quantitative PCR analyses were performed to establish the transcription profiles of RhoGTPase and RhoGEF genes during differentiation. Small hairpin RNA was used to knock down genes of interest.

Results: Of the 18 RhoGTPases and 76 RhoGEFs, the expression of three genes was upregulated by RANKL: the RhoGTPase RhoU/Wrch1, the Dbl family exchange factor Arhgef8/Net1, and the CZH family exchange factor Dock5. The inductions were observed in gene array and real-time quantitative PCR experiments performed in RAW264.7 cells. They were further confirmed in bone marrow macrophages and hematopoietic stem cells. Silencing of Wrch1 and Arhgef8 expression severely inhibited differentiation and affected osteoclast morphology. Dock5 suppression was lethal in osteoclast precursors while having no effect in fibroblasts.

Conclusions: We identified three genes among RhoGTPase signaling pathways that are upregulated during RANKL-induced osteoclastogenesis. These genes are novel essential actors in osteoclasts, most likely through the control of actin cytoskeleton dynamics.
Osteoclastic Bone Degradation and the Role of Different Cysteine Proteinases and Matrix Metalloproteinases: Differences Between Calvaria and Long Bone
Authors: Everts Vincent , Korper Wolf , Hoeben Kees A , Jansen Ineke DC , Bromme Dieter , Cleutjens Kitty BJM , Heeneman Sylvia , Peters Christoph , Reinheckel Thomas , Saftig Paul , Beertsen Wouter
Published: August 2006

Osteoclastic bone degradation involves the activity of cathepsin K. We found that in addition to this enzyme other, yet unknown, cysteine proteinases participate in digestion. The results support the notion that osteoclasts from different bone sites use different enzymes to degrade the collagenous bone matrix.

Introduction: The osteoclast resorbs bone by lowering the pH in the resorption lacuna, which is followed by secretion of proteolytic enzymes. One of the enzymes taken to be essential in resorption is the cysteine proteinase, cathepsin K. Some immunolabeling and enzyme inhibitor data, however, suggest that other cysteine proteinases and/or proteolytic enzymes belonging to the group of matrix metalloproteinases (MMPs) may participate in the degradation. In this study, we investigated whether, in addition to cathepsin K, other enzymes participate in osteoclastic bone degradation.

Materials and Methods: In bones obtained from mice deficient for cathepsin K, B, or L or a combination of K and L, the bone-resorbing activity of osteoclasts was analyzed at the electron microscopic level. In addition, bone explants were cultured in the presence of different selective cysteine proteinase inhibitors and an MMP inhibitor, and the effect on resorption was assessed. Because previous studies showed differences in resorption by calvarial osteoclasts compared with those present in long bones, in all experiments, the two types of bone were compared. Finally, bone extracts were analyzed for the level of activity of cysteine proteinases and the effect of inhibitors hereupon.

Results: The analyses of the cathepsin-deficient bone explants showed that, in addition to cathepsin K, calvarial osteoclasts use other cysteine proteinases to degrade bone matrix. It was also shown that, in the absence of cathepsin K, long bone osteoclasts use MMPs for resorption. Cathepsin L proved to be involved in the MMP-mediated resorption of bone by calvarial osteoclasts; in the absence of this cathepsin, calvarial osteoclasts do not use MMPs for resorption. Selective inhibitors of cathepsin K and other cysteine proteinases showed a stronger effect on calvarial resorption than on long bone resorption.

Conclusions: Our findings suggest that (1) cathepsin K–deficient long bone osteoclasts compensate the lack of this enzyme by using MMPs in the resorption of bone matrix; (2) cathepsin L is involved in MMP-mediated resorption by calvarial osteoclasts; (3) in addition to cathepsin K, other, yet unknown, cysteine proteinases are likely to participate in skull bone degradation; and finally, (4) the data provide strong additional support for the existence of functionally different bone-site specific osteoclasts.
Prediction of Hip Fracture Risk by Quantitative Ultrasound in More Than 7000 Swiss Women ≥70 Years of Age: Comparison of Three Technologically Different Bone Ultrasound Devices in the SEMOF Study
Authors: Krieg Marc-Antoine , Cornuz Jacques , Ruffieux Christiane , Van Melle Guy , Büche Daniel , Dambacher Maximilian A , Hans Didier , Hartl Florian , Häuselmann Hansjorg J , Kraenzlin Marius , Lippuner Kurt , Neff Maurus , Pancaldi Pierro , Rizzoli Rene , Tanzi Franco , Theiler Robert , Tyndall Alan , Wimpfheimer Claus , Burckhardt Peter
Published: August 2006

To compare the prediction of hip fracture risk of several bone ultrasounds (QUS), 7062 Swiss women ≥70 years of age were measured with three QUSs (two of the heel, one of the phalanges). Heel QUSs were both predictive of hip fracture risk, whereas the phalanges QUS was not.

Introduction: As the number of hip fracture is expected to increase during these next decades, it is important to develop strategies to detect subjects at risk. Quantitative bone ultrasound (QUS), an ionizing radiation-free method, which is transportable, could be interesting for this purpose.

Materials and Methods: The Swiss Evaluation of the Methods of Measurement of Osteoporotic Fracture Risk (SEMOF) study is a multicenter cohort study, which compared three QUSs for the assessment of hip fracture risk in a sample of 7609 elderly ambulatory women ≥70 years of age. Two QUSs measured the heel (Achilles+; GE-Lunar and Sahara; Hologic), and one measured the heel (DBM Sonic 1200; IGEA). The Cox proportional hazards regression was used to estimate the hazard of the first hip fracture, adjusted for age, BMI, and center, and the area under the ROC curves were calculated to compare the devices and their parameters.

Results: From the 7609 women who were included in the study, 7062 women 75.2 ± 3.1 (SD) years of age were prospectively followed for 2.9 ± 0.8 years. Eighty women reported a hip fracture. A decrease by 1 SD of the QUS variables corresponded to an increase of the hip fracture risk from 2.3 (95% CI, 1.7, 3.1) to 2.6 (95% CI, 1.9, 3.4) for the three variables of Achilles+ and from 2.2 (95% CI, 1.7, 3.0) to 2.4 (95% CI, 1.8, 3.2) for the three variables of Sahara. Risk gradients did not differ significantly among the variables of the two heel QUS devices. On the other hand, the phalanges QUS (DBM Sonic 1200) was not predictive of hip fracture risk, with an adjusted hazard risk of 1.2 (95% CI, 0.9, 1.5), even after reanalysis of the digitalized data and using different cut-off levels (1700 or 1570 m/s).

Conclusions: In this elderly women population, heel QUS devices were both predictive of hip fracture risk, whereas the phalanges QUS device was not.