bluuebunny/crossref_metadata_2025 huggingface dataset:
On feasibility examination of DS‐CDMA systems with imperfect successive interference cancellation
Authors: Zhou Zhaorong , Feng Gang , Zhang Yide , Li Lemin
Published: February 2010

In DS‐CDMA systems with the successive interference cancellation (SIC) technique, there areK! possible decoding orders forKactive users and the decoding order has considerable impact on system performance. Once the constraints on the received powers of mobile stations and the bit‐energy‐to‐interference‐power‐spectral‐density ratio requirements are satisfied under some decoding order of SIC, the system is feasible. Otherwise, if the constraints are violated under all possible decoding orders, the system is infeasible. It is highly time‐consuming to examine the system feasibility directly by using the usual exhaustive search method (ESM) for a system with even moderate number of users. In this paper, we propose an efficient approach for examining the feasibility of DS‐CDMA systems with imperfect SIC. The proposed approach has significantly lower computational complexity than that of ESM and thus benefits the quick decisions of admission control and/or scheduling, which are essential for Quality of Service provisioning in DS‐CDMA systems. Furthermore, we theoretically prove that the system under the resultant decoding order obtained by the proposed approach is able to achieve the lowest outage probability among all possible decoding orders. We conduct extensive simulation experiments, and the numerical results validate our analysis and demonstrate the effectiveness of our approach. Copyright © 2010 John Wiley & Sons, Ltd.
Visual experience and age affect synaptic organization in the mushroom bodies of the desert ant Cataglyphis fortis
Authors: Stieb Sara Mae , Muenz Thomas Sebastian , Wehner Rüdiger , Rössler Wolfgang
Published: February 2010

Desert ants of the genus Cataglyphis undergo an age‐related polyethism from interior workers involved in brood care and food processing to short‐lived outdoor foragers with remarkable visual navigation capabilities. The quick transition from dark to light suggests that visual centers in the ant's brain express a high degree of plasticity. To investigate structural synaptic plasticity in the mushroom bodies (MBs)—sensory integration centers supposed to be involved in learning and memory—we immunolabeled and quantified pre‐ and postsynaptic profiles of synaptic complexes (microglomeruli, MG) in the visual (collar) and olfactory (lip) input regions of the MB calyx. The results show that a volume increase of the MB calyx during behavioral transition is associated with a decrease in MG numbers in the collar and, less pronounced, in the lip. Analysis of tubulin‐positive profiles indicates that presynaptic pruning of projection neurons and dendritic expansion in intrinsic Kenyon cells are involved. Light‐exposure of dark‐reared ants of different age classes revealed similar effects. The results indicate that this structural synaptic plasticity in the MB calyx is primarily driven by visual experience rather than by an internal program. This is supported by the fact that dark‐reared ants age‐matched to foragers had MG numbers comparable to those of interior workers. Ants aged artificially for up to 1 year expressed a similar plasticity. These results suggest that the high degree of neuronal plasticity in visual input regions of the MB calyx may be an important factor related to behavior transitions associated with division of labor. © 2010 Wiley Periodicals, Inc. Develop Neurobiol 70: 408–423, 2010
An application of Ag(III) complex chemiluminescence system for the determination of enoxacin in capsule and biological fluid
Authors: Chen Peiyun , Sun Hanwen
Published: February 2010

Ag(III) complex chemiluminescence (CL) system was applied for the determination of enoxacin (ENX). The CL conditions of [Ag(HIO6)2]5−H2SO4ENX systems without any luminescence reagent were investigated and optimized. Under the optimized conditions, the CL intensity was proportional to the concentration of ENX in the range from 6.6 × 10−5 to 3.3 × 10−3 g/L. The limit of detection (s/n = 3) was 2.0 × 10−5 g/L. The recovery of ENX from the spiked pharmaceutical preparations was in the range of 82.9–108% with a relative standard deviation of 1.9–3.0%. For spiked serum and urine samples the recovery of ENX was in the range of 83.7–110% with a relative standard deviation of 1.1–2.8%. The proposed method was applied successfully to the determination of the drug in capsule, serum and urine samples. Copyright © 2010 John Wiley & Sons, Ltd.
Estimating measurement uncertainty in quantitative methods not based on chromatography for doping control purposes
Authors: Van Eenoo P. , Van Renterghem P. , Dimopoulou C. H. , Delbeke F.T. , Georgakopoulos C. G.
Published: February 2010

Estimation of measurement uncertainty (MU) for quantitative results is a requirement of ISO/IEC17025. This concept is well established for chromatographic methods in doping control and forensic analysis. For non‐chromatographic methods, however, very few practical methodologies have been published. In this paper, the applicability of a top‐down model, established for estimating uncertainty in chromatography, was evaluated for two other methodologies with different sets of raw data as a starting point. The first case study involves the estimation of MU for the determination of haematological parameters. In this case, a large data set of quality control material and proficiency testing results was available to establish MU. The second case study involves the estimation of MU for the recently approved method for the determination of human growth hormone misuse. In this case the amount of data available to establish MU was limited to results from method validation and a basic set of analysis data. In both cases a methodology based upon long‐term bias, long‐term imprecision and—eventually—a correction for standard impurity is proposed. The proposed methodology can be regarded as a dynamic procedure, which allows re‐evaluation of MU on a regular basis. Finally, a concept for the verification and evaluation of MU estimations using proficiency testing results is proposed. Copyright © 2010 John Wiley & Sons, Ltd.
Synthesis, Cytotoxicity and Antibacterial Studies of p‐Methoxybenzyl‐Substituted and Benzyl‐Substituted N‐Heterocyclic Carbene–Silver Complexes
Authors: Patil Siddappa , Claffey James , Deally Anthony , Hogan Megan , Gleeson Brendan , Menéndez Méndez Luis Miguel , Müller‐Bunz Helge , Paradisi Francesca , Tacke Matthias
Published: February 2010

p‐Methoxybenzyl‐substituted and benzyl‐substituted N‐heterocyclic carbene (NHC) [(3a–c) and (6a–c)] precursors were synthesised from the reaction of 1H‐imidazole (1a), 4,5‐dichloro‐1H‐imidazole (1b), and 1H‐benzimidazole (1c) with p‐methoxybenzyl bromide (2) and benzyl bromide (5). These NHC precursors were then treated with silver(I) acetate to yield the NHC–silver complexes [1,3‐bis(4‐methoxybenzyl)imidazol‐2‐ylidene]silver(I) acetate (4a), [4,5‐dichloro‐1,3‐bis(4‐methoxybenzyl)imidazol‐2‐ylidene]silver(I) acetate (4b), [1,3‐bis(4‐methoxybenzyl)benzimidazol‐2‐ylidene]silver(I) acetate (4c), (1,3‐dibenzylimidazol‐2‐ylidene)silver(I) acetate (7a), (1,3‐dibenzyl‐4,5‐dichloroimidazol‐2‐ylidene)silver(I) acetate (7b), and (1,3‐dibenzylbenzimidazol‐2‐ylidene)silver(I) acetate (7c), respectively. The NHC precursor 3c, four NHC–silver complexes 4c and 7a–c were characterised by single‐crystal X‐ray diffraction method. The preliminary antibacterial activity of all the compounds was studied against Gram‐negative bacteria Escherichia coli, and Gram‐positive bacteria Staphylococcus aureus using the Kirby–Bauer disk‐diffusion method. Almost all the NHC–silver complexes have shown high antibacterial activity compared to the NHC precursors. In addition, the NHC–silver complexes had their cytotoxicity investigated through MTT‐based preliminary in vitro testing on the Caki‐1 cell lines in order to determine their IC50 values. NHC–silver complexes 4a–c and 7a–c were found to have IC50 values of 7.3 (+/–6), 12.7(+/–3), 25.2 (+/–5), 2.5 (+/–3), 10.8 (+/–4) and 12.5 (+/–4) μM respectively on the Caki‐1 cell line.
Solid Solution Sr2Sc1+xRe1–xO6 with a Perovskite­‐Like Structure: Phase Transitions and Magnetic Properties
Authors: Mikhailova Daria , Narayanan Narendirakumar , Voss Andrea , Ehrenberg Helmut , Trots Dmytro M. , Ritter Clemens , Eckert Jürgen , Fuess Hartmut
Published: February 2010

The solid solution Sr2Sc1+xRe1–xO6 with a monoclinicperovskite‐like structure has been prepared with the composition range 0 ≤ x ≤ 0.333. When x ≤ 0, other phases compete with the formation of Sr2Sc1+xRe1–xO6. Crystallographic details of Sr2ScReO6 (x = 0) were investigated by neutron and synchrotron powder diffraction in the temperature range 10–1153 K. Upon cooling, Sr2ScReO6 undergoes structural phase transitions: from cubic Fm‐3m to tetragonal I4/m at ca. 800 K and from tetragonal I4/m to monoclinic P21/n at ca. 350 K, and a two‐phase field (monoclinic P21/n + tetragonal I4/m) was observed below 75 K. The latter transition coincides with a magnetic rearrangement from the paramagnetic to antiferromagnetic state. Compositions with x > 0 demonstrate no antiferromagnetic ordering.
Synthesis of α‐Amino Nitriles from Carbonyl Compounds, Amines, and Trimethylsilyl Cyanide: Comparison between Catalyst‐Free Conditions and the Presence of Tin Ion‐Exchanged Montmorillonite
Authors: Wang Jiacheng , Masui Yoichi , Onaka Makoto
Published: February 2010

In the absence of catalysts, the three‐component, one‐pot synthesis of α‐amino nitriles proceeded using various aldehydes and ketones together with amines and trimethylsilyl cyanide (TMSCN) in high yields under neat conditions at room temperature. The addition order of the reagents had a significant influence on the yields of the desired α‐amino nitriles. In contrast, when tin ion‐exchanged montmorillonite (Sn‐Mont), prepared by the ion‐exchange of sodium montmorillonite (Na‐Mont) with a tin tetrachloride solution, was used as a catalyst, the reaction rates significantly increased compared with those without catalysts, and the range of the applicable carbonyl compounds was also extended: structurally diverse aromatic, aliphatic and heteroatom‐containing carbonyl compounds, including sterically hindered ketones as well as aliphatic and aromatic amines, were converted into the desired α‐amino nitriles in good to excellent yields with short reaction times under mild conditions. Sn‐Mont showed a better catalytic activity than proton or other metal ion‐exchanged montmorillonites, supported SnO2 catalysts and the previously reported homogeneous or heterogeneous catalysts. The recovered catalyst was reused several times without loss of catalytic performance. Along with the expansion of the interlayer space of Sn‐Mont, the strong Brønsted acid and Lewis acid nature of Sn‐Mont derived from protons and SnO2 nanoparticles present in the interlayers of Sn‐Mont likely played important and cooperative roles in the high catalytic activity.
The Electropolymerization of 2,6‐Diaminopyridine and Its Application as Mercury Ion Selective Electrode
Authors: Bakhtiarzadeh Fariba , Ab Ghani Sulaiman
Published: February 2010

A composite graphite (CG) electrode modified with poly(2,6‐diaminopyridine) (PDAP) was used as solid state‐ion selective electrode for determination of mercury. The electrooxidation of monomer 2, 6 diaminopyridine (DAP) onto CG was accomplished from the 30 mM DAP in 5% H2SO4 and 0.5 M ZnSO4. The electrode displayed Nernstian response with slope of 28.4±1 mV decade−1 in concentration range of 1×10−6 to 1×10−1 M and in solution of pH 3–5. The limit of detection for electrode was 3×10−8 M with response time of 25 s. The electrode was also suitable as an indicator electrode in the potentiometric titration of Hg2+ with iodide.
Direct Electrochemistry and Electrocatalysis of Hemoglobin–TiO2 Whisker Film Modified Glassy Carbon Electrode
Authors: Song Min , Feng Xin , Lu Xiaohua , Wang Xuemei
Published: February 2010

In this study, HbTiO2 whisker nanocomposites are prepared by incorporating TiO2 whisker with hemoglobin (Hb). Our studies illustrate that the self‐assembled HbTiO2 whisker films could efficiently facilitate the direct electron transfer of Hb on glassy carbon electrode (GCE). Moreover, our results demonstrate that the catalytic activity to the reduction of H2O2 could be observed on the HbTiO2 whisker modified GCE and the photovoltaic effect of TiO2 whisker can greatly enhance the detection sensitivity of electrocatalytic reduction.
Highly Sensitive Electrochemical Sensor for Nitric Oxide Using the Self‐Assembled Monolayer of 1,8,15,22‐Tetraaminophthalocyanatocobalt(II) on Glassy Carbon Electrode
Authors: Sivanesan Arumugam , John Swamidoss Abraham
Published: February 2010

Glassy carbon (GC) electrode modified with a self‐assembled monolayer (SAM) of 1,8,15,22‐tetraaminophthalocyanatocobalt(II) (4α‐CoIITAPc) was used for the selective and highly sensitive determination of nitric oxide (NO). The SAM of 4α‐CoIITAPc was formed on GC electrode by spontaneous adsorption from DMF containing 1 mM 4α‐CoIITAPc. The SAM showed two pairs of well‐defined redox peaks corresponding to CoIII/CoII and CoIIIPc−1/CoIIIPc−2 in 0.2 M phosphate buffer (PB) solution (pH 2.5). The SAM modified electrode showed excellent electrocatalytic activity towards the oxidation of nitric oxide (NO) by enhancing its oxidation current with 310 mV less positive potential shift when compared to bare GC electrode. In amperometric measurements, the current response for NO oxidation was linearly increased in the concentration range of 3×10−9 to 30×10−9 M with a detection limit of 1.4×10−10 M (S/N=3). The proposed method showed a better recovery for NO in human blood serum samples.
Deformation pattern analysis and tectonic implications of a décollement level within the Central Apennines (Italy)
Authors: Tavani Stefano , Cifelli Francesca
Published: February 2010

This work reports structural and anisotropy of magnetic susceptibility (AMS) measurements from an Upper Miocene décollement level exposed in the central Apennine fold‐and‐thrust belt of Italy. The décollement level is located at the boundary between the Mesozoic‐Cenozoic carbonate sequence and the overlying Miocene‐Pliocene syn‐orogenic siliciclastic sediments and consists of a thick shear zone, mainly affecting detritic limestones, dominated by pressure solution cleavage oblique to the bedding.

In the study area, the décollement level was active during the early stages of evolution of the fold‐and‐thrust belt, when deeper décollement levels were active in more internal zones, and accounted for the bulk top‐to‐foreland translation of the siliciclastic portion of the multilayer. The increasing deformation led to the progressive foreland migration of deeper décollement levels (and of thrusts emanating from these levels) that were active in the more internal sectors. Consequently, the Mesozoic‐Cenozoic carbonate sequence was folded and faulted and the studied décollement became inactive and was incorporated into the fold‐and‐thrust belt. Pressure solution cleavage within the décollement became a passive marker that underwent rotations associated with later deformational phases. Results indicate that pressure solution cleavage registers two phases of deformation: (1) during thrusting and folding, when beds were folded and (2) at a later stage, when cleavage was rotated, together with thrusts and folds, about vertical axes. This second stage is interpreted as having been induced by the oblique inversion of a Liassic normal fault, during the Miocene compression. Copyright © 2010 John Wiley & Sons, Ltd.
Tumor‐specific mutation and downregulation of ING5 detected in oral squamous cell carcinoma
Authors: Cengiz Beyhan , Gunduz Esra , Gunduz Mehmet , Beder Levent Bekir , Tamamura Ryo , Bagci Cahit , Yamanaka Noboru , Shimizu Kenji , Nagatsuka Hitoshi
Published: February 2010

Our previous study showed high frequency of allelic loss at chromosome 2q37 region in oral cancer. This location contains several candidate tumor suppressor genes such as PPP1R7, ILKAP, DTYMK and ING5. We previously showed 3 members of inhibitor of growth (ING) family, ING1, ING3 and ING4 as tumor suppressor gene in head and neck cancer. As ING5 shows high homology with other members of ING genes including highly conserved carboxy‐terminal plant homeodomain and nuclear localization signal, we first picked up ING5 and examined it as a possible tumor suppressor in oral cancer. For this aim, mutation and mRNA expression status of ING5 in paired normal and oral squamous cell carcinoma samples were examined by reverse transcription polymerase chain reaction (RT‐PCR) and sequencing. Three missense mutations located within leucine zipper like (LZL) finger and novel conserved region (NCR) domains in ING5 protein were detected, probably abrogating its normal function. We also found 5 different alternative splicing variants of ING5. Then, we examined mRNA level of ING5 by quantitative real time reverse transcription polymerase chain reaction (qRT‐PCR) analysis, which demonstrated decreased expression of ING5 mRNA in 61% of the primary tumors as compared to the matched normal samples. In conclusion, tumor‐specific mutation and downregulation of ING5 mRNA suggested it as a tumor suppressor gene in oral squamous cell carcinoma.
Characteristic methylation profile in CpG island methylator phenotype‐negative distal colorectal cancers
Authors: An Byonggu , Kondo Yutaka , Okamoto Yasuyuki , Shinjo Keiko , Kanemitsu Yukihide , Komori Koji , Hirai Takashi , Sawaki Akira , Tajika Masahiro , Nakamura Tsuneya , Yamao Kenji , Yatabe Yasushi , Fujii Makiko , Murakami Hideki , Osada Hirotaka , Tani Tohru , Matsuo Keitaro , Shen Lanlan , Issa Jean‐Pierre J. , Sekido Yoshitaka
Published: February 2010

Aberrant DNA methylation is involved in colon carcinogenesis. Although the CpG island methylator phenotype (CIMP) is defined as a subset of colorectal cancers (CRCs) with remarkably high levels of DNA methylation, it is not known whether epigenetic processes are also involved in CIMP‐negative tumors. We analyzed the DNA methylation profiles of 94 CRCs and their corresponding normal‐appearing colonic mucosa with 11 different markers, including the five classical CIMP markers. The CIMP markers were frequently methylated in proximal CRCs (p < 0.01); however, RASSF1A methylation levels were significantly higher in distal CRCs, the majority of which are CIMP‐negative (p < 0.05). Similarly, methylation levels of RASSF1A and SFRP1 in the normal‐appearing mucosae of distal CRC cases were significantly higher than those in the proximal CRC cases (p < 0.05). They were also positively correlated with age (RASSF1A, p < 0.01; SFRP1, p < 0.01). Microarray‐based genome‐wide DNA methylation analysis of 18 CRCs revealed that 168 genes and 720 genes were preferentially methylated in CIMP‐negative distal CRCs and CIMP‐positive CRCs, respectively. Interestingly, more than half of the hypermethylated genes in CIMP‐negative distal CRCs were also methylated in the normal‐appearing mucosae, indicating that hypermethylation in CIMP‐negative distal CRCs is more closely associated with age‐related methylation. By contrast, more than 60% of the hypermethylated genes in CIMP‐positive proximal CRCs were cancer specific (p < 0.01). These data altogether suggest that CpG island promoters appear to be methylated in different ways depending on location, a finding which may imply the presence of different mechanisms for the acquisition of epigenetic changes during colon tumorigenesis.
Exogenous luminal nitric oxide exposure accelerates columnar transformation of rat esophagus
Authors: Endo Hiroyuki , Iijima Katsunori , Asanuma Kiyotaka , Ara Nobuyuki , Ito Hirotaka , Asano Naoki , Uno Kaname , Koike Tomoyuki , Imatani Akira , Shimosegawa Tooru
Published: February 2010

Exposure of the esophageal mucosa to refluxed gastroduodenal contents is recognized to be an important risk factor for Barrett's esophagus (BE). At the human gastroesophageal junction, nitric oxide is generated luminally through the enterosalivary recirculation of dietary nitrate, and in cases with gastroesophageal reflux, the site of luminal nitric oxide generation could shift to the distal esophagus. The aim of this study is to investigate whether exogenous luminal nitric oxide could promote the development of BE in rats. Sodium nitrite plus ascorbic acid were administered to a rat surgical model of BE, in which the gastroduodenal contents were refluxed into the esophagus to generate exogenous luminal nitric oxide in the esophagus by the acid‐catalyzed chemical reaction between the 2 reagents. The emergence of BE was evaluated histologically in the early phase (several weeks) after the surgery with or without exogenous nitric oxide administration. To elucidate the histogenesis of BE, CDX2, MUC2 and MUC6 expressions were investigated immunohistochemically. Coadministration of sodium nitrite plus ascorbic acid significantly accelerated the timing of emergence and increased the area of BE compared with controls. Administration of either reagent alone did not show any promotive effects on BE formation. Immunohistochemically, the columnar epithelium thus induced was similar to the specialized intestinal metaplasia in human BE. The results of this animal model study suggest that exogenous luminal nitric oxide could be involved in the pathogenesis of the columnar transformation of the esophagus. Further studies in human are warranted.
Genetic variation of PSCA gene is associated with the risk of both diffuse‐ and intestinal‐type gastric cancer in a Chinese population
Authors: Lu Yan , Chen Jianjian , Ding Yanbing , Jin Guangfu , Wu Juan , Huang Hua , Deng Bin , Hua Zhaolai , Zhou Yan , Shu Yongqian , Liu Ping , Hu Zhibin , Shen Jing , Xu Yaochu , Shen Hongbing
Published: February 2010

Prostate stem cell antigen (PSCA), a member of the LY‐6/Thy‐1 family of glycosylphosphatidylinositol‐anchored cell surface proteins, is considered to be involved in the cell‐proliferation inhibition and/or cell‐death induction activity. Two single nucleotide polymorphisms (SNPs) (rs2976392 and rs2294008) in the PSCA gene were recently identified as the susceptibility loci of gastric cancer, especially in diffuse type. Therefore, this study was to investigate whether these 2 SNPs were associated with the risk of gastric cancer in Chinese population. We genotyped rs2976392 and rs2294008 in PSCA in a case–control study including 1,053 incident gastric cancer patients and 1,100 cancer‐free controls in a high‐risk Chinese population. We found that variant genotypes of rs2976392 (GA/AA) were associated with a significantly 37% increased risk of gastric cancer (adjusted OR =1.37, 95% CI = 1.15–1.62), compared with variant homozygote GG, and the associations were all consistently significant in both intestinal and diffuse subtypes, and among different subgroups stratified by age, sex, drinking or smoking status. Interestingly, a significant multiplicative interaction between rs2976392 (GA/AA) and alcohol drinking was detected on the development of intestinal‐type gastric cancer (p = 0.009). However, rs2294008 variant genotypes (CT/TT) were associated with a nonsignificant increased risk of gastric cancer (adjusted OR = 1.14, 95% CI = 0.96–1.36). A small meta‐analysis including 5 case–control studies showed undoubtedly associations between PSCA rs2294008 and rs2976392 and gastric cancer risk (OR = 1.83, 95% CI: 1.29–2.60 and OR = 1.84, 95% CI: 1.33–2.56, respectively). These findings provide further evidence supporting that the genetic variants of PSCA gene may contribute to the gastric carcinogenesis.
MGMT activity, promoter methylation and immunohistochemistry of pretreatment and recurrent malignant gliomas: a comparative study on astrocytoma and glioblastoma
Authors: Christmann Markus , Nagel Georg , Horn Sigrid , Krahn Ulrike , Wiewrodt Dorothee , Sommer Clemens , Kaina Bernd
Published: February 2010

The DNA repair protein O6‐methylguanine‐DNA methyltransferase (MGMT) is a key player in tumor cell resistance. Promoter methylation, MGMT activity and immunohistochemistry are used for determining the MGMT status. However, it is unclear whether MGMT promoter methylation correlates with MGMT activity and whether MGMT promoter methylation of the pretreatment tumor predicts the MGMT status of recurrences. To address these questions, we determined MGMT activity promoter methylation and immunoreactivity in pretreatment and recurrent glioblastomas (GB, WHO Grade IV), and in astrocytomas (WHO Grade III). We show that GB that were promoter methylated display a range of 0–62 fmol/mg MGMT and tumors that were nonmethylated 0–423 fmol/mg protein. For astrocytomas, promoter‐methylated samples displayed 0–28 fmol/mg and, nonmethylated samples, 23–107 fmol/mg. No correlation was found between the intensity of promoter methylation and MGMT activity. Given a threshold level of 30 fmol/mg of protein, we found a correlation between promoter methylation and no/low MGMT activity in 82.4% of the tumors. This high correlation level was only observed when tumors were excluded showing a hemimethylated promoter (20%). Therefore, classification of hemimethylated tumors remains questionable. Further, we show that 39.1% of pretreatment GB and 5.3% of recurrences were promoter methylated, which is in line with the observed increase of MGMT activity in recurrences. Although individual exceptions were found, the data show an overall correlation between promoter methylation and lack/low MGMT activity in GB and astrocytomas. We also show that promoter methylation assay is superior over immunohistochemistry in determining the MGMT status defined by a given MGMT activity level.
Dramatic increase in cortical thickness induced by femoral marrow ablation followed by a 3-month treatment with PTH in rats
Authors: Zhang Qing , Carlson Jodi , Ke Hua Zhu , Li Jiliang , Kim Michael , Murphy Kieran , Mehta Nozer , Gilligan James , Vignery Agnès
Published: February 2010

We previously reported that following mechanical ablation of the marrow from the midshaft of rat femurs, there is a rapid and abundant but transient growth of bone, and this growth is enhanced and maintained over a 3-week period by the bone anabolic hormone parathyroid hormone (PTH). Here, we asked whether further treatment with PTH or bisphosphonates can extend the half-life of the new bone formed in lieu of marrow. We subjected the left femur of rats to mechanical marrow ablation and treated the animals 5 days a week with PTH for 3 weeks (or with vehicle as a control) to replace the marrow by bone. Some rats were euthanized and used as positive controls or treated with vehicle, PTH, or the bisphosphonate alendronate for a further 9 weeks. We subjected both femurs from each rat to soft X-ray, peripheral quantitative computed tomography (pQCT), micro-computed tomography (µCT), dynamic histomorphometry analysis, and biomechanical testing. We also determined the concentrations of serum osteocalcin to confirm the efficacy of PTH. Treatment with PTH for 3 months dramatically enhanced endosteal and periosteal bone formation, leading to a 30% increase in cortical thickness. In contrast, alendronate protected the bone that had formed in the femoral marrow cavity after marrow ablation and 3 weeks of treatment with PTH but failed to promote endosteal bone growth or to improve the biomechanical properties of ablated femurs. We further asked whether calcium-phosphate cements could potentiate the formation of bone after marrow ablation. Marrow cavities from ablated femurs were filled with one of two calcium-phosphate cements, and rats were treated with PTH or PBS for 84 days. Both cements helped to protect the new bone formed after ablation. To some extent, they promoted the formation of bone after ablation, even in the absence of any anabolic hormone. Our data therefore expand the role of PTH in bone engineering and open new avenues of investigation to the field of regenerative medicine and tissue engineering. Local bone marrow aspiration in conjunction with an anabolic agent, a bisphosphonate, or a calcium-phosphate cement might provide a new platform for rapid preferential site-directed bone growth in areas of high bone loss. © 2010 American Society for Bone and Mineral Research
Individual trabeculae segmentation (ITS)–based morphological analysis of high-resolution peripheral quantitative computed tomography images detects abnormal trabecular plate and rod microarchitecture in premenopausal women with idiopathic osteoporosis
Authors: Liu X Sherry , Cohen Adi , Shane Elizabeth , Stein Emily , Rogers Halley , Kokolus Shannon L , Yin Perry T , McMahon Donald J , Lappe Joan M , Recker Robert R , Guo X Edward
Published: February 2010

Idiopathic osteoporosis (IOP) in premenopausal women is a poorly understood entity in which otherwise healthy women have low-trauma fracture or very low bone mineral density (BMD). In this study, we applied individual trabeculae segmentation (ITS)–based morphological analysis to high-resolution peripheral quantitative computed tomography (HR-pQCT) images of the distal radius and distal tibia to gain greater insight into skeletal microarchitecture in premenopausal women with IOP. HR-pQCT scans were performed for 26 normal control individuals and 31 women with IOP. A cubic subvolume was extracted from the trabecular bone compartment and subjected to ITS-based analysis. Three Young's moduli and three shear moduli were calculated by micro–finite element (µFE) analysis. ITS-based morphological analysis of HR-pQCT images detected significantly decreased trabecular plate and rod bone volume fraction and number, decreased axial bone volume fraction in the longitudinal axis, increased rod length, and decreased rod-to-rod, plate-to-rod, and plate-to-plate junction densities at the distal radius and distal tibia in women with IOP. However, trabecular plate and rod thickness did not differ. A more rod-like trabecular microstructure was found in the distal radius, but not in the distal tibia. Most ITS measurements contributed significantly to the elastic moduli of trabecular bone independent of bone volume fraction (BV/TV). At a fixed BV/TV, plate-like trabeculae contributed positively to the mechanical properties of trabecular bone. The results suggest that ITS-based morphological analysis of HR-pQCT images is a sensitive and promising clinical tool for the investigation of trabecular bone microstructure in human studies of osteoporosis. © 2010 American Society for Bone and Mineral Research
A simple method for correlative light and scanning electron microscopy of human iliac crest bone biopsies: Qualitative observations in normal and osteoporotic subjects
Authors: Dr. Dempster D. W. , Shane E. , Horbert W. , Lindsay R.
Published: February 2010

Despite the fact that the scanning electron microscope (SEM) offers a number of unique advantages for the investigation of bone structure, this instrument has seldom been applied in studies of the iliac crest bone biopsy. Here we describe a very simple method of preparing iliac crest biopsies for examination in the SEM after the routine histomorphometric analysis has been performed. With observations on biopsies from normal subjects and patients with osteoporosis, the paper illustrates the potential of the method for performing correlative light and scanning electron microscopical studies and for gaining new information on the three-dimensional architecture of trabecular bone.
Binding of calcitonin and calcitonin gene-related peptide to calvarial cells and renal cortical membranes
Authors: Seitz Patricia K. , Thomas Mary L. , Dr. Cooper Cary W.
Published: February 2010

Binding of calcitonin (CT) and calcitonin gene-related peptide (CGRP) to rat hemicalvariae and renal membranes was examined in an effort to determine whether CT and CGRP interact with the same bone cell binding site, and to see whether the binding pattern was similar for bone and renal cortex. Specific binding of 125I-salmon CT to rat calvariae was inhibited by unlabeled salmon, porcine, or human CT, but not by rat CGRP. Binding of 125I-rat CGRP to calvariae was inhibited by CGRP and high doses of salmon CT, but not by human or porcine CT. Binding of 125I-salmon CT to renal membranes was inhibited by unlabeled salmon CT or rat CGRP, but no specific binding of 125I-rat CGRP could be detected. The results suggest that separate bone cell receptors for CT and CGRP exist and that CGRP can interact with renal receptors for CT.
Effects of age and estrogen on calcium absorption in the rat
Authors: Russell Jean E. , Morimoto Shigeto , Birge Stanley J. , Fausto Aurora , Avioli Louis V.
Published: February 2010

In order to differentiate the relative effects of age and estrogen on rates of calcium absorption and serum levels of parathyroid hormone and calcitonin, the effect of oophorectomy with and without estrogen replacement (2 weeks) was studied in rats for 30- or 120-day periods. Whereas oophorectomy for 30 days resulted in a significant decrease in serum calcium and an increase in serum phosphate, no change in either calcium or phosphate was observed in the 120-day oophorectomized animals. iPTH decreased in both the 30- and 120-day oophorectomized animals although these changes were not significant at the .05 level. Whereas no significant change in basal circulating calcitonin occurred in the 30-day oophorectomized rats, it decreased significantly in the older animals following the ablative procedure. Forty-five days following estrogen deprivation, calcitonin release to a calcium secretagogue was significantly blunted. Intestinal calcium absorption decreased with age, and unlike the increments in calcium absorption observed in the younger estrogen-repleted, 30-day oophorectomized rat, no change in calcium absorption was observed when estrogens were administered to the older, 120-day oophorectomized rat. The accumulated data suggest that the effects of estrogen loss on the hormonal control of bone metabolism and calcium absorption are age dependent, and that estrogen contributes significantly to changes in calcium homeostasis observed in the maturing rat.
Prostaglandins change cell shape and increase intercellular gap junctions in osteoblasts cultured from rat fetal calvaria
Authors: Shen Victor , Rifas Leonard , Kohler Gail , Peck William A.
Published: February 2010

Mounting experimental evidence indicates that osteoblasts may be cellular intermediaries in the local activation of bone remodeling. To elucidate the role of these cells in activation, we examined the effects of prostaglandins (PGs), known resorption stimulators, on cell shape and intercellular junctional relationships in osteoblasts cultured from rat fetal calvaria. Exposure to PGE2 and PGE1, promoters of bone resorption, rapidly (within 20 min) converted the osteoblasts from a flattened to a stellate shape (shape change), and markedly increased the appearance of intercellular (gap) junctions within 10 min. Both effects were directly related to the prostaglandin concentration, as little as 1 nM being effective. PGE1, but not PGB1, PGF1α, PGD2, and PGF2α, mimicked the substantial effect of PGE2 on shape change. Shape change and gap junction formation appear to arise independently. PTH, an inducer of shape change, did not affect the number of gap junctions appreciably. Colchicine, a microtubule polymerization inhibitor, and trifluoperazine, an inhibitor of calmodulin action, blunted PGE2-mediated shape change but not the effect of PGE2 on gap junctions. Shape change and gap junction formation may be important events in local activation, shape changes in surface osteoblasts serving to expose bone surfaces which are chemotactic for osteoclasts and gap junctions propagating locally initiated activation messages.
Serum bone GLA-protein in growth hormone deficient children
Authors: Dr. Delmas Pierre D. , Chatelain Pierre , Malaval Luc , Bonne Graziela
Published: February 2010

Serum bone GLA-protein (BGP), a sensitive and specific marker of bone formation, was measured in 54 normal children and in 50 children with growth disorders. In normal children, the pattern of variations of serum BGP with age was similar to the pattern of variations of the growth velocity. Mean serum BGP was very high during the first year of life (25.3 ± 8.5 ng/ml), decreased to 14.8 ± 2.2 ng/ml from 2 to 6 years, increased to 18.4 ± 4.1 ng/ml from 7 to 10 years and to 18.8 ± 6.5 ng/ml from 11 to 14 years. After puberty, mean sBGP decreased to 12.9 ± 5.4 ng/ml from 15 to 18 years and to 6.5 ± 1.4 ng/ml in young adults. In 32 patients with untreated growth hormone (GH) deficiency, mean sBGP was markedly lower than in age matched controls (6.8 ± 4.4 ng/ml vs. 17.5 ± 4.9 ng/ml, p < .001). In 19 patients with GH deficiency who were undergoing treatment with human GH, sBGP was higher than in untreated patients (20.5 ± 9.3 ng/ml vs. 6.8 ± 4.4 ng/ml, p < .001) and was not different from controls. Repeated measurements performed in 14 GH-deficient patients under chronic GH therapy showed that serum BGP: (1) increased in most patients during treatment (p < .005); (2) was correlated with the duration of treatment (p < .001); (3) decreased to pretreatment values after discontinuing therapy. In conclusion, our data suggest that serum BGP is a sensitive marker of skeletal growth in normal children and in children with growth deficiency, and that measurement of serum BGP might be useful to assess the effects on bone metabolism of hormones and/or drugs that stimulate bone growth and maturation.
Effects of retinoic acid on the activation and fusion of mouse alveolar macrophages induced by 1α,25-dihydroxyvitamin D3
Authors: Miyaura Chisato , Segawa Akihisa , Nagasawa Hiroshi , Abe Etsuko , Dr. Suda Tatsuo
Published: February 2010

1α, 25-dihydroxyvitamin D3 [1α,25(OH)2D3] directly induces both fusion and cytotoxicity in murine alveolar macrophages. Unlike 1α,25(OH)2D3, retinoic acid per se did not induce fusion of alveolar macrophages, but it greatly enhanced the 1α,25(OH)2D3-induced fusion every time the macrophages were treated simultaneously with the two vitamins. The giant cells induced by the two vitamins were much larger than those induced by 1α,25(OH)2D3 alone. The macrophages treated with 1α,25(OH)2D3 started to fuse 36 h after the addition of the vitamin, whereas the macrophages pretreated with retinoic acid for 24 h began to fuse immediately after 1α,25(OH)2D3 was added. 1α,25(OH)2D3 and retinoic acid activated alveolar macrophages similarly, measured by the enhancement of glucose consumption and the induction of cytotoxicity against tumor cells, though 1α,25(OH)2D3 was 100 times more potent than retinoic acid on a molar basis. Simultaneous treatment with physiological concentrations of 1α,25(OH)2D3 (0.12 nM) and retinoic acid (10 nM) induced cytotoxicity additively. Morphological examinations revealed that the treated cells were enlarged and flattened with numerous filopodia. These results clearly indicate that both 1α,25(OH)2D3 and retinoic acid similarly activate alveolar macrophages, and the activated state is prerequisite to the fusion of macrophages induced by 1α,25(OH)2D3.
Restoration of spinal bone in osteoporotic men by treatment with human parathyroid hormone (1–34) and 1,25-dihydroxyvitamin D
Authors: Dr. Slovik David M. , Rosenthal Daniel I. , Doppelt Samuel H. , Potts John T. , Daly Margaret A. , Campbell Julie A. , Neer Robert M.
Published: February 2010

Daily subcutaneous injection of a synthetic human parathyroid hormone fragment, combined with daily ingestion of 1,25(OH)2 vitamin D, significantly increased trabecular bone density in the spine (p < .01), and improved intestinal calcium and phosphorus absorption and total body retention of dietary calcium and phosphorus in middle-aged men with idiopathic osteoporosis. The increases in spinal bone mineral were marked and progressive during a year of treatment. These results indicate that increasing intestinal absorption of dietary calcium while simultaneously stimulating new bone formation with small doses of parathyroid hormone can restore spinal bone in osteoporotic men.
Aluminum-associated bone disease in chronic renal failure: High prevalence in a long-term dialysis population
Authors: Andress Dennis L. , Maloney Norma A. , Dr. Endres David B. , Sherrard Donald J.
Published: February 2010

Twenty-seven asymptomatic patients treated with hemodialysis longer than 8 years (mean 12.9 ± 3.1 years) underwent bone biopsy to determine the prevalence of aluminum-associated bone disease. None had excess aluminum exposure from the dialysate. Ten patients (37%) had aluminum-associated bone disease as defined by a bone formation rate (BFR) below normal in the presence of stainable bone aluminum that covered more than 25% of the trabecular surface. The predominant type of bone histology in this group was the aplastic lesion characterized by low bone turnover, a decreased number of osteoblasts, and lack of excess unmineralized osteoid. Osteoblastic osteoid was highly correlated with stainable surface bone aluminum (r = - .82, p < .001). Among the dynamic bone parameters, the double-tetracycline labeled surface was a more sensitive indicator of impaired bone function than was the bone apposition rate (BAR), since half of the patients with aluminum-associated bone disease had a normal BAR. In all of the biopsies the extent of double-labeled surfaces was inversely proportional to the amount of stainable aluminum on the bone surface (r = - .71, p < .001), whereas stainable bone aluminum did not correlate with BAR. In seven of the patients with aluminum-associated bone disease, amino-terminal PTH levels were in the normal range while only one patient had a normal plasma mid-region PTH. PTH correlated directly with osteoblastic osteoid, BFR, and double-labeled surfaces. These results indicate that long-term oral aluminum intake in hemodialysis patients results in a high prevalence of aluminum-associated bone disease. The decrease in osteoblast number appears to be the major mechanism for the low bone formation. Whether aluminum adversely affects the osteoblast population directly or decreases osteoblast number indirectly via suppression of PTH secretion remains undecided.
The effects of immobilization on bone histomorphometry in rats
Authors: Turner Russell T. , Bell Norman H.
Published: February 2010

To determine whether immobilization acts directly on bone by alteration of mechanical loading or systemically, studies of the effects of immobilization were carried out on histomorphometry of diaphyses of tibiae and on subcutaneous implants of demineralized allogenic bone matrix of rats. The right hind leg of growing rats was denervated by severing the tibial nerve. A sham operation on the right hind leg was performed in control animals. Bone formation at the endosteal and periosteal surfaces was significantly lower in tibiae from limbs with severed nerves as compared to tibiae from the intact limbs of nerve-sectioned rats and from both limbs of sham-operated control rats. Bone formation was decreased at both 3 and 7 weeks after immobilization. The decreased formation resulted in significant reductions in cross-sectional area. At 3 weeks post denervation, the periosteal bone formation rate was lower in tibiae of intact limbs from denervated rats as compared to tibiae from intact limbs of sham-operated animals. This finding was attributed to reduced physical activity of the denervated rats. In the implants, nerve section did not alter the amount of implant matrix resorbed, the amount of bone matrix synthesized, or the amount of calcium in the implant. These findings support the hypothesis that inhibition of bone formation at the tibial diaphysis in response to immobilization resulted from altered mechanical loading and not from the production of substances acting systemically. Whereas the mean medullary area of tibiae was not altered by nerve section, it was decreased in tibiae of all groups compared to the values of basal controls, indicating that bone formation was greater than bone resorption. The findings are interpreted to mean that, in the rat, reducing the mechanical loading of an extremity inhibits bone formation at the tibial diaphysis of the affected limb and does not influence bone resorption at that site.
Preferential inhibition of cytokine-stimulated bone resorption by recombinant interferon gamma
Authors: Dr. Gowen Maxine , Nedwin Glenn E. , Mundy Gregory R.
Published: February 2010

It is likely that immune cells in the bone marrow produce factors which are involved in the local control of bone remodeling. Immune cell products such as interleukin-1 and the tumor necrosis factors are potent stimulators of bone resorption in vitro. In this paper, we have studied the effects of recombinant murine interferonγ on bone resorption stimulated by these agents and the systemic calcium-regulating hormones 1,25(OH)2 vitamin D3 and parathyroid hormone. We found that interferon-7 completely abolished bone resorption stimulated by the cytokines interleukin-1, tumor necrosis factor α and tumor necrosis factor ß. In contrast, parathyroid hormone- and 1,25(OH)2 vitamin D3-stimulated bone resorption were not significantly affected by the addition of interferon-γ under the same conditions. Parathyroid hormone-stimulated bone resorption was inhibited slightly when larger concentrations of interferon-γ were used for more prolonged periods. The inhibitory effects on cytokine-stimulated bone resorption occurred at interferon concentrations of 100 U/ml (half-maximal) to 300 U/ml (complete inhibition). This relatively selective inhibition of cytokine-stimulated bone resorption by an immune cell product may have physiological significance in the local control of trabecular bone volume and bone remodeling.
Effect of estrogen/gestagen and 24R,25-dihydroxyvitamin D3 therapy on bone formation in postmenopausal women
Authors: Dr. Thomsen Karsten , Riis Bente , Christiansen Claus
Published: February 2010

The effect of two different estrogen/gestagen regimens and 24R,25-(OH)2-cholecalciferol on bone formation was studied in a randomized trial with 144 healthy postmenopausal women. Urinary excretion (UE) of 99m-technetium-diphosphonate and serum alkaline phosphatase (AP) was determined before and then once a year for 2 years of treatment. Both estimates of bone formation showed highly significant decreases (p < .001) to normal premenopausal levels in women receiving unopposed 17β-estradiol or in a sequential combination with progestagen, whereas unchanged high values were found in the groups receiving 24R,25-(OH)2D3 and placebo. The data show that bone turnover increases in early postmenopausal women concomitantly with the loss of bone mass, and that hormonal substitutional therapy normalizes the total skeletal turnover as well as preventing bone loss.
Regulation by calcium of parathyroid hormone mRNA in cultured parathyroid tissue
Authors: Brookman Jenny J. , Farrow Sheelagh M. , Nicholson Linda , O'riordan Jeffrey L.H. , Dr. Hendy Geoffrey N.
Published: February 2010

We have examined the effect of changes in the concentration of extracellular calcium on parathyroid hormone mRNA in both short-term (hours) and long-term (days) cultures of bovine parathyroid tissue. Using a 32P-labeled PreProPTH cDNA probe, PTH mRNA was measured by gel blot hybridization of total RNA from tissue slices incubated for 4 h in low (0.5 m M) or high (5 m M) calcium concentrations and also by dot blot hybridization of cytoplasmic RNA extracted from aggregates of partially dispersed cells cultured up to 72 h in low (0.4 m M), normal (1 m M), or high (3 m M) calcium concentrations. PTH mRNA was unchanged over 4 h while high calcium had suppressed PTH secretion. However PTH mRNA did respond during long-term culture. By 24 h in high calcium there was a 50% suppression which was maintained for a further 48 h. PTH mRNA in normal calcium remained unchanged over 72 h while in low calcium it had increased slightly by 48 h. In contrast to the effect seen in cultured bovine parathyroid cells, PTH mRNA in human parathyroid adenoma cells cultured for 48 h in high calcium was decreased by only 10%.