bluuebunny/crossref_metadata_2025 huggingface dataset:
Novel platforms for vascular carriers with controlled geometry
Authors: Pillai Jonathan D. , Dunn Stuart S. , Napier Mary E. , DeSimone Joseph M.
Published: June 2011

The first‐generation platforms for vascular drug delivery adopted spherical morphologies. These carriers relied primarily on the size dependence of the enhanced permeability and retention effect to passively target vasculature, resulting in inefficient delivery due to significant variation in endothelial permeability. Enhanced delivery typically requires active targeting via receptor‐mediated endocytosis by surface conjugation of targeting ligands. However, vascular carriers (VCs) still face numerous challenges en route to reaching their targets before delivery. The control of carrier shape offers opportunities to overcome in vivo barriers and enhance vascular drug delivery. Geometric features influence the ability of carrier particles to navigate physiological flow patterns, evade biological clearance mechanisms, sustain circulation, adhere to the vascular surface, and finally transport across or internalize into the endothelium. Although previous formulation strategies limited the fabrication of nonspherical carriers, numerous recent advances in both top‐down and bottom‐up fabrication techniques have enabled shape modulation as a key design element. As part of a series on vascular drug delivery, this review focuses on recent developments in novel vascular platforms with controlled geometry that enhance or modulate delivery functions. Starting with an overview of controlled geometry platforms, we review their shape‐dependent functional characteristics for each stage of their vascular journey in vivo. We sequentially explore carrier geometries that evade reticuloendothelial system uptake, display enhanced circulation persistence and margination dynamics in flow, encourage adhesion to the vascular surface or extravasation through endothelium, and impact extravascular transport and cell internalization. The eventual biodistribution of VCs results from the culmination of their successive navigation of all these barriers and is profoundly influenced by their morphology. To enhance delivery efficacy, carrier designs synergistically combining controlled geometry with standard drug delivery strategies such as targeting moieties, surface decorations, and bulk material properties are discussed. Finally, we speculate on possibilities for innovation, harnessing shape as a design parameter for the next generation of vascular drug delivery platforms. © 2011 IUBMB IUBMB Life, 2011
Pharmacokinetic study of two acetylcholinesterase reactivators, trimedoxime and newly synthesized oxime K027, in rat plasma
Authors: Karasova Jana Zdarova , Chladek Jaroslav , Hroch Milos , Josef Fusek , Hnidkova Daniela , Kuca Kamil
Published: June 2011

K027 [1‐(4‐hydroxyiminomethylpyridinium)‐3‐(4‐carbamoylpyridinium)–propane dibromide] is a promising new reactivator of organophosphate‐ or organophosphonate‐inhibited acetylcholinesterase (AChE) with low acute toxicity and broad spectrum efficacy. The aim of the present study was to compare the pharmacokinetics of both compounds. Male Wistar rats (body weight = 320 ± 10 g) were administered a single intramuscular dose of K027 (22.07 mg kg−1) and an equimolar dose of trimedoxime. Blood was collected at various time intervals until 180 min. Plasma samples were analyzed by reversed‐phase HPLC with ultraviolet (UV) detection. The recovery of both oximes from the plasma was approximately 90% and a linear relationship (R2 > 0.998) was observed between the peak areas and concentrations of calibrated standards in the range 1–100 µg ml−1. Near‐identical plasma profiles were obtained for both compounds. No differences were found in the mean ± SD values of Cmax (18.6 ± 2.5 vs 20.0 ± 6.3 µg ml−1, P = 0.72) and AUC0–180min (2290 ± 304 vs 2269 ± 197 min µg ml−1, P = 0.84). However, the percentage coefficient of variation of the first‐order rate constant of absorption (ka) was 3‐fold higher (P < 0.01) providing evidence for more erratic absorption of intramuscular trimedoxime as compared with K027. In conclusion, oxime K027 might have superior pK properties that may be translated in its faster absorption and subsequent tissue distribution. Copyright © 2011 John Wiley & Sons, Ltd.
Nandrolone androgenic hormone presents genotoxic effects in different cells of mice
Authors: do Carmo Carolina Almeida , Gonçalves Álvaro Luiz Martini , Salvadori Daisy Maria Fávero , Maistro Edson Luis
Published: June 2011

Nandrolone is an androgenic–anabolic steroid (AAS) with diverse medical applications but taken indiscriminately by some to rapidly increase muscle mass. The aim of this study was to evaluate the genotoxic and clastogenic potential of nandrolone (deca‐durabolin®) in vivo in different cells of mice, using the comet assay and micronucleus test, respectively. The animals received subcutaneous injection of the three doses of the steroid (1.0, 2.5 and 5.0 mg kg−1 body weight). Cytotoxicity was assessed by scoring 200 consecutive total polychromatic (PCE) and normochromatic (NCE) erythrocytes (PCE–NCE ratio). The results showed a significant dose‐related increase in the frequency of DNA damage in leukocytes, liver, bone marrow, brain and testicle cells at the three tested doses and a significant increase of the micronucleated polychromatic erythrocytes at all tested doses. Under our experimental conditions, the nandrolone steroid hormone showed genotoxic and clastogenic effects when administered subcutaneously to mice. Copyright © 2011 John Wiley & Sons, Ltd.
In vivo characterization of tumor and tumor vascular network using multi‐modal imaging approach
Authors: Kalchenko Vyacheslav , Madar‐Balakirski Noa , Meglinski Igor , Harmelin Alon
Published: June 2011

We present a multi‐modal optical diagnostic approach utilizing a combined use of Fluorescence Intravital Microscopy (FIM), Dynamic Light Scattering (DLS) and Spectrally Enhanced Microscopy (SEM) modalities for in vivo imaging of tumor vascular network and blood microcirculation. FIM is used for imaging of tumor surroundings and microenvironment, SEM provides information regarding blood vessels topography, whereas DLS is applied for functional imaging of vascular network and blood microcirculation. This complementary combination of the imaging approaches is extremely useful for functional in vivo imaging of blood vasculature and tumor microenvironment. The technique has also a great potential in vascular biology and can significantly expand the capabilities of tumor angiogenesis studies and notably contribute to the development of cancer treatment. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Thermoresponsive poly(N‐isopropylacrylamide)‐g‐methylcellulose hydrogel as a three‐dimensional extracellular matrix for cartilage‐engineered applications
Authors: Sá‐Lima Helena , Tuzlakoglu Kadriye , Mano João F. , Reis Rui L.
Published: June 2011

Recent advances in tissue engineering and regenerative medicine fields can offer alternative solutions to the existing techniques for cartilage repair. In this context, a variety of materials has been proposed, and the injectable hydrogels are among the most promising alternatives. The aim of this work is to explore the ability of poly(N‐isopropylacrylamide)‐g‐methylcellulose (PNIPAAm‐g‐MC) thermoreversible hydrogel as a three‐dimensional support for cell encapsulation toward the regeneration of articular cartilage through a tissue engineering approach. The PNIPAAm‐g‐MC copolymer was effectively obtained using ammonium‐persulfate and N,N,N′,N′‐tetramethylethylenediamine as initiator as confirmed by Fourier transform infrared spectroscopy and 1H NMR results. The copolymer showed to be temperature responsive, becoming a gel at temperatures above its lower critical solution temperature (∼ 32°C) while turning into a liquid below it. Results obtained from the MTS test showed that extracts of the hydrogel were clearly noncytotoxic to L929 fibroblast cells. ATDC5 cells, a murine chondrogenic cell line, were used as the in vitro model for this study; they were encapsulated at high cell density within the hydrogel and cultured for up to 28 days. PNIPAAm‐g‐MC did not affect the cell viability and proliferation, as indicated by both MTS and DNA assays. The results also revealed an increase in synthesis of glycosoaminoglycans within culture time measured by the dimethylmethylene blue quantification assay. These results suggest the viability of using PNIPAAm‐g‐MC thermoresponsive hydrogel as a three‐dimensional scaffold for cartilage tissue engineering using minimal‐invasive strategies. © 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part A:, 2011.
Influence of processing parameters on pore structure of 3D porous chitosan–alginate polyelectrolyte complex scaffolds
Authors: Florczyk Stephen J. , Kim Dae‐Joon , Wood David L. , Zhang Miqin
Published: June 2011

Fabrication of porous polymeric scaffolds with controlled structure can be challenging. In this study, we investigated the influence of key experimental parameters on the structures and mechanical properties of resultant porous chitosan–alginate (CA) polyelectrolyte complex (PEC) scaffolds, and on proliferation of MG‐63 osteoblast‐like cells, targeted at bone tissue engineering. We demonstrated that the porous structure is largely affected by the solution viscosity, which can be regulated by the acetic acid and alginate concentrations. We found that the CA PEC solutions with viscosity below 300 Pa.s yielded scaffolds of uniform pore structure and that more neutral pH promoted more complete complexation of chitosan and alginate, yielding stiffer scaffolds. CA PEC scaffolds produced from solutions with viscosities below 300 Pa.s also showed enhanced cell proliferation compared with other samples. By controlling the key experimental parameters identified in this study, CA PEC scaffolds of different structures can be made to suit various tissue engineering applications. © 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part A:, 2011.
A new approach in self‐etching adhesive formulations: Replacing HEMA for surfactant dimethacrylate monomers
Authors: Zanchi Cesar Henrique , Münchow Eliseu Aldrighi , Ogliari Fabricio Aulo , de Carvalho Rodrigo Varella , Chersoni Stefano , Prati Carlo , Demarco Flávio Fernando , Piva Evandro
Published: June 2011

This study evaluated the influence of surfactant dimethacrylates (SD) on the resin‐to‐dentin microtensile bond strength (μTBS) and characterized the interfacial micromorphology of the hybrid layer of the experimental HEMA‐free self‐etching systems. Five experimental HEMA‐free two‐step self‐etching systems containing different SD (Bis‐EMA 10, Bis‐EMA 30, PEG 400, PEG 1000, and PEG 400 UDMA) and a HEMA‐containing system (control) were compared. Each experimental adhesive system was applied and resin composite restorations were incrementally built up in bovine incisors. After 24 h, restored teeth were sectioned to obtain 24 sticks per group. Thereafter, the specimens were subjected to the μTBS test. Data (MPa) were analyzed by One‐way ANOVA and Tukey's test. Adhesive‐dentin interfaces were analyzed through Scanning Electron Microscopy (SEM). The adhesive system formulated with PEG 400 UDMA produced μTBS similar to the HEMA‐containing group and statistically higher than the HEMA‐free groups. Similar failure percentages were observed in the PEG 400 UDMA and the control group. In the SEM analysis, all the adhesive systems presented similar partially demineralized hybrid layer (1.5–3.0 μm thickness) with well‐formed resin tags. All SD presented reasonable initial μTBS, with the PEG 400 UDMA being a promising monomer to be considered as a HEMA substitute in adhesive systems compositions. © 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2011.
Mechanical stability of two‐step chemically deposited hydroxyapatite coating on Ti substrate: Effects of various surface pretreatments
Authors: Zavgorodniy Alexander V. , Borrero‐López Oscar , Hoffman Mark , LeGeros Racquel Z. , Rohanizadeh Ramin
Published: June 2011

The success of implants in orthopaedic and dental load‐bearing applications crucially depends on the initial biological fixation of implants in surrounding bone tissues. Using hydroxyapatite (HA) coating on Ti implant as carrier for bone morphogenetic proteins (BMPs) may promote the osteointegration of implants; therefore, reduce the risk of implant failure. The goal of this study was to develop an HA coating method in conditions allowing the incorporation of protein‐based drugs into the coating materials, while achieving a mechanical stable coating on Ti implant. HA coatings were deposited on six different groups of Ti surfaces: control (no pretreatment), pretreated with alkali, acid, heat at 800°C, grit blasted with Al2O3, and grit blasted followed by heat treatment. HA coating was prepared using a two‐step procedure. First step was the chemical deposition of a monetite coating on Ti substrate in acidic condition at 75°C and the second step was the hydrolysis of the monetite coating to HA. Coatings were characterized by scanning electron microscope (SEM), energy‐dispersive X‐ray spectroscopy (EDS), and X‐ray diffraction (XRD). The roughness of substrates and coatings was measured using profilometry technique. The mechanical stability of the coatings deposited on the pretreated substrates was assessed using scratch test. The coatings deposited on the grit‐blasted Ti surface demonstrated superior adhesive properties with critical shearing stress 131.6 ± 0.2 MPa. © 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2011.
Biocompatibility of magnesium particles evaluated by in vitro cytotoxicity and genotoxicity assays
Authors: Di Virgilio Ana L. , Reigosa Miguel , de Mele Monica Fernández Lorenzo
Published: June 2011

Mg is a biodegradable biomaterial which may release particles (MP) to the environment. The possible cyto‐ and genotoxic effects of MP derived from magnesium powder (mesh 325) were analyzed on rat osteosarcoma UMR106 cells in order simulate the effect of Mg debris. Neutral red (NR) incorporation and acridine orange/ethidium bromide (AO/EB) staining techniques were used as endpoints to analyze the cytotoxic effects at 25–1000 μg/mL concentration range. Genotoxicity was estimated according to micronucleus (MN) formation and the Comet assay (CA). Results showed that MP size changes with time due to corrosion. Changes in lysosomal activity were observed after 24 h only at 1000 μg/mL. Accordingly, AO/EB staining showed a significant decrease in the number of living cells at 500 μg/mL. Transmission electronic microscopy showed MP internalization (60 and 200 nm diameter) in cells after 2‐h treatment, whereas no MP was detected after 24 h. A significant dose‐dependent increase in MN frequencies was observed at 25–100 μg/mL range (nontoxic range). DNA damage induction was assessed by CA only at 500 μg/mL. Results showed dose‐dependent cytotoxic and genotoxic effects of MP on UMR106 cells with different threshold values of MP concentration. © 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2011.
A completely autologous valved conduit prepared in the open form of trileaflets (type VI biovalve): Mold design and valve function in vitro
Authors: Nakayama Yasuhide , Yahata Yuki , Yamanami Masashi , Tajikawa Tsutomu , Ohba Kenkichi , Kanda Keiichi , Yaku Hitoshi
Published: June 2011

In‐body tissue, architecture technology represents a promising approach for the development of living heart valve replacements and preparation of a series of biovalves. To reduce the degree of regurgitation and increase the orifice ratio, we designed a novel mold for a type VI biovalve. The mold had an outer diameter of 14 mm for implantation in beagles, and it was prepared by assembling two silicone rods with a small aperture (1 mm) between them. One rod had three protrusions of the sinus of Valsalva, whereas the other was almost cylindrical. When the molds were embedded in the subcutaneous pouches of beagles for 1 month, the native connective tissues that subsequently developed covered the entire outer surface of the molds and migrated into the aperture between the rods. The mold from both sides of the harvested cylindrical implant was removed, and homogenous well‐balanced trileaflets were found to be separately formed in the open form with a small aperture at the three commissure parts inside the developed conduit, which had a thick homogenous wall even in the sinus of Valsalva. Exposure of the obtained biovalves to physiological aortic valve flow in beagles revealed proper opening motion with a wide orifice area. The closure dynamics were suboptimal, probably due to the reduction in the size of the sinus of Valsalva. The mechanical behavior of this biovalve might allow its use as a living aortic valve replacement. © 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2011.
Development and in vitro studies of a polyethylene terephthalate‐gold nanoparticle scaffold for improved biocompatibility
Authors: Whelove Ona E. , Cozad Matthew J. , Lee Byung‐Doo , Sengupta Shramik , Bachman Sharon L. , Ramshaw Bruce J. , Grant Sheila A.
Published: June 2011

Polyethylene terephthalate (PET) mesh is one of the most commonly used synthetic biomaterials for tension‐free hernia repair. In an effort to improve the biocompatibility of PET mesh, gold nanoparticles (AuNP) in various concentrations were conjugated to the PET surface to develop PET‐AuNP scaffolds. These novel scaffolds were characterized with Fourier transform infrared spectroscopy (FT‐IR), scanning electron microscopy (SEM), and differential scanning calorimetry (DSC) to assess the addition of functional groups, presence of AuNPs, and thermal stability of the modified PET mesh, respectively. The biocompatibility of the PET‐AuNP scaffolds was evaluated through in vitro cell culture assays. The cellularity of cells exposed to the PET‐AuNP scaffolds, as well as the scaffolds' ability to reduce reactive oxygen species, was assessed using L929 murine fibroblasts. Antimicrobial properties of AuNPs conjugated to PET mesh were tested against the bacteria Pseudomonas aeruginosa. Results from the FT‐IR showed presence of COOH groups while SEM displayed bonding of AuNPs to the PET surface. DSC results indicated that the PET more than likely did not undergo any detrimental degradation due to the surface modification. Results from the in vitro studies showed that AuNPs, in optimal concentrations (1× concentrations), enhanced cellularity, reduced ROS, and reduced bacteria adhesion to PET. These studies demonstrated enhanced biocompatibility of the AuNP conjugated PET mesh over pristine PET mesh. © 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2011.
Synthesis of spherical hydroxyapatite granules with interconnected pore channels using camphene emulsion
Authors: Yang Jung‐Ho , Kim Kyo‐Han , You Chang‐Kook , Rautray Tapash R. , Kwon Tae‐Yub
Published: June 2011

The aim of this study was to fabricate porous spherical hydroxyapatite (HA) granules with interconnected pore channels for use as a bone graft substitute. Various weights of camphene porogen were mixed with nano‐sized HA powder (camphene/HA = 0, 10, 30, 50, 70, and 90% w/w) and 10% gelatin aqueous solution then added to the mixture. The water‐in‐oil emulsion method was employed to obtain spherical‐shaped granules, of which those 1000–2000 μm in diameter were selectively classified using a standard sieve set. Thermogravimetric analysis and X‐ray diffraction were used to determine optimal sintering conditions. The sintered granules were characterized using field emission‐scanning electron microscopy (FE‐SEM), microcomputed tomography, and porosimetry. The pore size and porosity of spherical HA granules increased with the addition of camphene. Granules with a HA/camphene ratio of 90% (HG90) demonstrated macropores (>50 μm) with interconnected pore channels (porosity: 58.49%). In addition, FE‐SEM examination of HG90 coated with polycaprolactone showed that the granule may hold promise as a drug delivery carrier. We concluded that these HG90 granules merit consideration as a bone graft substitute or drug delivery carrier in bone tissue engineering. © 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2011.
Experimental and computational models to investigate the effect of adhesion on the mechanical properties of bone‐cement composites
Authors: Helgason B. , Stirnimann P. , Widmer R. , Ferguson S. J.
Published: June 2011

A generic finite element approach was developed to study the effect of adhesion on the mechanical response of bone cement composites and validated against literature data. The results showed that a zero friction bone‐cement (PMMA) interface conditions captured the results of the experimental testing better than assuming a fully bonded interface. An experimental model for studying the effect of interface adhesion in a bone‐cement like composite was also developed in the present study. The results using this model indicate that the difference in Young's modulus and ultimate strength between a fully bonded interface and unbonded interface is approximately 30% for bone volume fraction similar to what can be found in osteoporotic vertebrae. Apart from concluding that bone to cement adhesion is a major contributor to the mechanical response of bone‐cement composites, our studies based on the generic FE approach also indicate that the mechanical properties of the cement is the most important contributor to the resulting mechanical properties of the composite at bone volume fraction relevant in terms of vertebroplasty treatment. © 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2011.
Neomycin enhances extracellular matrix stability of glutaraldehyde crosslinked bioprosthetic heart valves
Authors: Friebe Vincent M. , Mikulis Brandon , Kole Sourav , Ruffing Christy S. , Sacks Michael S. , Vyavahare Naren R.
Published: June 2011

Glutaraldehyde (GLUT) crosslinked porcine aortic heart valves are continued to be extensively used in heart valve replacement surgeries. GLUT does not crosslink glycosaminoglycans in the tissue and we have demonstrated that GAG loss is associated with tissue degeneration. In this study, we examined the ability of neomycin to enhance GLUT crosslinking to stabilize GAGs, as well as provide evidence of improved functional integrity. Neomycin enhanced GLUT crosslinked (NG) leaflets exposed to collagenase and elastase enzymes exhibited an increased resistance to proteolytic degradation. Furthermore, NG leaflets exhibited small but significant increases in collagen denaturation temperatures when compared to that of standard GLUT crosslinked BHVs. NG leaflets subjected to storage, accelerated cyclic fatigue, and in vitro enzyme mediated GAG degradation revealed improved GAG stabilization versus standard GLUT crosslinked valves, which sustained substantial decreases in GAG content. Ultrastructural analysis using transmission electron microscopy qualitatively confirmed NG leaflets preserved GAGs after enzymatic degradation. Biomechanical analyses demonstrated that NG leaflets were functionally similar to GLUT tissues but were slightly stiffer under both planar biaxial tension and under flexure. Interestingly, after GAGase treatment, GLUT tissues showed increased areal compliance and reduced hysteresis, while NG leaflets were unchanged. Collectively, NG cross‐linking functionally insulated the tissue from GAG digestion, and imparted modest additional matrix stiffness but maintained tissue hysteresis properties. © 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2011.
A synthesis route to nanoparticle dicalcium silicate for biomaterials research
Authors: Booncharoen W. , Jaroenworaluck A. , Stevens R.
Published: June 2011

Dicalcium silicate (Ca2SiO4) has been reported as an interesting candidate for biomaterials use due to its attractive bioactive properties. Here, we report on how dicalcium silicate was prepared by a sol–gel route using calcium nitrate tetrahydrate and tetraorthosilicate as the precursors chemicals for CaO and SiO2, respectively. The synthesized powders were characterized using thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), Fourier transform infrared (FTIR) spectroscopy, X‐ray diffraction (XRD), Brunauer‐Emmett‐Teller (BET) method, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). High purity dicalcium silicate at a CaO/SiO2 molar ratio of 2:1 could be formed by the sol–gel method without a washing process and was then calcined at 800°C. The effects of the molar ratio of CaO/SiO2, the washing process, and the calcination temperature have been shown to affect the purity, the formation, and the particle size of the nanoparticles, which have been investigated and discussed. © 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2011.
Corrosion of Mg alloy AZ91D in the presence of living cells
Authors: Seuss F. , Seuss S. , Turhan M. C. , Fabry B. , Virtanen S.
Published: June 2011

Mg and Mg alloys are of interest for biodegradable implants as they readily corrode in biological fluids, and dissolved Mg ions are nontoxic. Even though it is well known that Mg dissolution leads to pH increase in the surroundings, the effect of the corrosion‐induced alkalization on the biological environment has not been studied in detail. We therefore explored the interactions between corrosion‐induced pH increase and cell growth on Mg alloy AZ91D surface. Cell adhesion and spreading on the alloy surface is unimpeded initially. However, with time a large fraction of cells de‐adhere. We attribute this to the observed increase of the pH in the cell culture medium in the process of alloy dissolution. Cytotoxicity tests with HeLa cells grown on glass surfaces confirm that cell death increases with increasing alkalinity of the cell culture medium. We also show that a the cells that adhere on the Mg alloy surface act as a corrosion‐blocking surface layer. In consequence, a slower pH increase in the medium takes place when the alloy surface is covered with cells. Electrochemical impedance spectroscopy measurements (EIS) verify that a cell layer slows down the corrosion process. © 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2011.
Uncertainties in the prevention and treatment of glucocorticoid-induced osteoporosis
Authors: Hansen Karen E , Wilson H Alexander , Zapalowski Carol , Fink Howard A , Minisola Salvatore , Adler Robert A
Published: June 2011

Much knowledge has accrued since the 2001 American College of Rheumatology (ACR) guidelines were published to assist clinicians in the prevention and treatment of glucocorticoid-induced osteoporosis (GIO). Therefore, the ACR undertook a comprehensive effort to review the literature and update the GIO guidelines [Grossman JM, Gordon R, Ranganath VK, et al. American College of Rheumatology 2010 recommendations for the prevention and treatment of glucocorticoid-induced osteoporosis. Arthritis Care Res (Hoboken). 2010;62:1515–1526]. Herein, we review the new guidelines for JBMR readers, highlighting the changes introduced by the 2010 publication. We discuss several patient scenarios for which the new treatment guidelines do not apply, or for which our committee interprets existing literature differently and suggests an alternative approach. © 2011 American Society for Bone and Mineral Research
Effects of antiresorptive treatment on nonvertebral fracture outcomes
Authors: Mackey Dawn C , Black Dennis M , Bauer Douglas C , McCloskey Eugene V , Eastell Richard , Mesenbrink Peter , Thompson John R , Cummings Steven R
Published: June 2011

Various definitions of nonvertebral fracture have been used in osteoporosis trials, precluding comparisons of efficacy. Using only subgroups of nonvertebral fractures for trial outcomes may underestimate the benefits and cost-effectiveness of treatments. The objectives of this study were to determine (1) the effect of antiresorptive treatment on various nonvertebral fracture outcomes, (2) whether risk reduction from antiresorptive treatment is greater for nonvertebral fractures that have stronger associations with low BMD, and (3) sample size estimates for clinical trials of osteoporosis treatments. Study-level data were combined from five randomized fracture-prevention trials of antiresorptive agents that reduce the risk of nonvertebral fracture in postmenopausal women: alendronate, clodronate, denosumab, lasofoxifene, and zoledronic acid. Pooled effect estimates were calculated with random-effects models. The five trials included 30,118 women; 2997 women had at least one nonvertebral fracture. There was no significant heterogeneity between treatments for any outcome (all p > 0.10). Antiresorptive treatment had similar effects on all fractures (summary hazard ratio [HR] = 0.76, 95% CI 0.70–0.81), high-trauma fractures (HR = 0.74, 95% CI 0.57–0.96), low-trauma fractures (HR = 0.77, (95% CI 0.71–0.83), nonvertebral six (ie, hip, pelvis, leg, wrist, humerus, and clavicle) fractures (HR = 0.73, 95% CI 0.66–0.80), other than nonvertebral six fractures (HR = 0.78, 95% CI 0.70–0.87), and all fractures other than finger, face, and toe (HR = 0.75, 95% CI 0.70–0.81). Risk reduction was not greater for fractures with stronger associations with low BMD (p = 0.77). A trial of all nonvertebral fractures would require fewer participants (n = 2641 per arm) than one of a subgroup of six fractures (n = 3289), for example. In summary, antiresorptive treatments reduced all nonvertebral fractures regardless of degree of trauma or special groupings, supporting the use of all nonvertebral fractures as a standard endpoint of osteoporosis trials and the basis for estimating the benefits and cost-effectiveness of treatments. © 2011 American Society for Bone and Mineral Research
Impact of oncopediatric dosing regimen of zoledronic acid on bone growth: Preclinical studies and case report of an osteosarcoma pediatric patient
Authors: Battaglia Séverine , Dumoucel Sophie , Chesneau Julie , Heymann Marie-Françoise , Picarda Gaëlle , Gouin François , Corradini Nadège , Heymann Dominique , Redini Françoise
Published: June 2011

Osteosarcoma and Ewing sarcoma represent the two most frequent primary bone tumors that arise in the pediatric population. Despite recent improvement in their therapeutic management, no improvement in survival rate has been achieved since early 1980 s. Among new therapeutic approaches, bisphosphonates are promising candidates as potent inhibitors of bone resorption. However, their effects on bone growth must be studied at dosing regimen corresponding to pediatric protocols. To this aim, several protocols using zoledronic acid (ZOL) were developed in growing mice (50 µg/kg every 2 days × 10). Parameters of bone remodeling and bone growth were investigated by radiography, micro–computed tomography, histology, and biologic analyses. Extramedullar hematopoiesis was searched for in spleen tissue. A transient inhibitory effect of ZOL was observed on bone length, with a bone-growth arrest during treatment owing to an impressive increase in bone formation at the growth plate level (8- to 10-fold increase in BV/TV). This sclerotic band then shifted into the diaphysis as soon as endochondral bone formation started again after the end of ZOL treatment, revealing that osteoclasts and osteoblasts are still active at the growth plate. In conclusion, endochondral bone growth is transiently disturbed by high doses of ZOL corresponding to the pediatric treatment of primary bone tumors. These preclinical observations were confirmed by a case report in a pediatric patient treated in the French OS2006 protocol over 10 months who showed a growth arrest during the ZOL treatment period with normal gain in size after the end of treatment. © 2011 American Society for Bone and Mineral Research
Direct costs of fractures in Canada and trends 1996–2006: A population-based cost-of-illness analysis
Authors: Leslie William D , Metge Colleen J , Azimaee Mahmoud , Lix Lisa M , Finlayson Gregory S , Morin Suzanne N , Caetano Patricia
Published: June 2011

Cost-of-illness (COI) analysis is used to evaluate the economic burden of illness in terms of health care resource (HCR) consumption. We used the Population Health Research Data Repository for Manitoba, Canada, to identify HCR costs associated with 33,887 fracture cases (22,953 women and 10,934 men) aged 50 years and older that occurred over a 10-year period (1996–2006) and 101,661 matched control individuals (68,859 women and 32,802 men). Costs (in 2006 Canadian dollars) were estimated for the year before and after fracture, and the change (incremental cost) was modeled using quantile regression analysis to adjust for baseline covariates and to study temporal trends. The greatest total incremental costs were associated with hip fractures (median $16,171 in women and $13,111 for men), followed by spine fractures ($8,345 in women and $6,267 in men). The lowest costs were associated with wrist fractures ($663 in women and $764 in men). Costs for all fracture types were greater in older individuals (p < 0.001). Similar results were obtained with regression-based adjustment for baseline factors. Some costs showed a slight increase over the 10 years. The largest temporal increase in women was for hip fracture ($13 per year, 95% CI $6–$21, p < 0.001) and in men was for humerus fracture ($11 per year, 95% CI $3–$19, p = 0.007). At the population level, hip fractures were responsible for the largest proportion of the costs after age 80, but the other fractures were more important prior to age 80. We found that there are large incremental health care costs associated with incident fractures in Canada. Identifying COI from HCR use offers a cost baseline for measuring the effects of evidence-based guidelines implementation. © 2011 American Society for Bone and Mineral Research
MafB interacts with Gcm2 and regulates parathyroid hormone expression and parathyroid development
Authors: Kamitani-Kawamoto Akiyo , Hamada Michito , Moriguchi Takashi , Miyai Masashi , Saji Fumie , Hatamura Ikuji , Nishikawa Keizo , Takayanagi Hiroshi , Hitoshi Seiji , Ikenaka Kazuhiro , Hosoya Toshihiko , Hotta Yoshiki , Takahashi Satoru , Kataoka Kohsuke
Published: June 2011

Serum calcium and phosphate homeostasis is critically regulated by parathyroid hormone (PTH) secreted by the parathyroid glands. Parathyroid glands develop from the bilateral parathyroid-thymus common primordia. In mice, the expression of transcription factor Glial cell missing 2 (Gcm2) begins in the dorsal/anterior part of the primordium on embryonic day 9.5 (E9.5), specifying the parathyroid domain. The parathyroid primordium then separates from the thymus primordium and migrates to its adult location beside the thyroid gland by E15.5. Genetic ablation of gcm2 results in parathyroid agenesis in mice, indicating that Gcm2 is essential for early parathyroid organogenesis. However, the regulation of parathyroid development at later stages is not well understood. Here we show that transcriptional activator v-maf musculoaponeurotic fibrosarcoma oncogene homologue B (MafB) is developmentally expressed in parathyroid cells after E11.5. MafB expression was lost in the parathyroid primordium of gcm2 null mice. The parathyroid glands of mafB+/− mice were mislocalized between the thymus and thyroid. In mafB−/− mice, the parathyroid did not separate from the thymus. Furthermore, in mafB−/− mice, PTH expression and secretion were impaired; expression levels of renal cyp27b1, one of the target genes of PTH, was decreased; and bone mineralization was reduced. We also demonstrate that although Gcm2 alone does not stimulate the PTH gene promoter, it associates with MafB to synergistically activate PTH expression. Taken together, our results suggest that MafB regulates later steps of parathyroid development, that is, separation from the thymus and migration toward the thyroid. MafB also regulates the expression of PTH in cooperation with Gcm2. © 2011 American Society for Bone and Mineral Research
Resveratrol promotes osteogenesis of human mesenchymal stem cells by upregulating RUNX2 gene expression via the SIRT1/FOXO3A axis
Authors: Tseng Pei-Chi , Hou Sheng-Mou , Chen Ruey-Jien , Peng Hsiao-Wen , Hsieh Chi-Fen , Kuo Min-Liang , Yen Men-Luh
Published: June 2011

Reports of the bone-protective effects of resveratrol, a naturally occurring phytoestrogen and agonist for the longevity gene SIRT1, have highlighted this compound as a candidate for therapy of osteoporosis. Moreover, SIRT1 antagonism enhances adipogenesis. There has been speculation that resveratrol can promote osteogenesis through SIRT1, but the mechanism remains unclear. In this study we investigated the molecular mechanism of how resveratrol can modulate the lineage commitment of human mesenchymal stem cells to osteogenesis other than adipogenesis. We found that resveratrol promoted spontaneous osteogenesis but prevented adipogenesis in human embryonic stem cell–derived mesenchymal progenitors. Resveratrol upregulated the expression of osteo-lineage genes RUNX2 and osteocalcin while suppressing adipo-lineage genes PPARγ2 and LEPTIN in adipogenic medium. Furthermore, we found that the osteogenic effect of resveratrol was mediated mainly through SIRT1/FOXO3A with a smaller contribution from the estrogenic pathway. Resveratrol activated SIRT1 activity and enhanced FOXO3A protein expression, a known target of SIRT1, in an independent manner. As a result, resveratrol increased the amount of the SIRT1-FOXO3A complex and enhanced FOXO3A-dependent transcriptional activity. Ectopic overexpression or silencing of SIRT1/FOXO3A expression regulated RUNX2 promoter activity, suggesting an important role for SIRT1-FOXO3A complex in regulating resveratrol-induced RUNX2 gene transcription. Further mutational RUNX2 promoter analysis and chromatin immunoprecipitation assay revealed that resveratrol-induced SIRT1-FOXO3A complex bound to a distal FOXO response element (−1269/−1263), an action that transactivated RUNX2 promoter activity in vivo. Taken together, our results describe a novel mechanism of resveratrol in promoting osteogenesis of human mesenchymal stem cells by upregulating RUNX2 gene expression via the SIRT1/FOXO3A axis. © 2011 American Society for Bone and Mineral Research
Parathyroid hormone signaling via Gαs is selectively inhibited by an NH2-terminally truncated Gαs: Implications for pseudohypoparathyroidism
Authors: Puzhko Svetlana , Goodyer Cynthia Gates , Kerachian Mohammad Amin , Canaff Lucie , Misra Madhusmita , Jüppner Harald , Bastepe Murat , Hendy Geoffrey N
Published: June 2011

Pseudohypoparathyroid patients have resistance predominantly to parathyroid hormone (PTH), and here we have examined the ability of an alternative Gαs-related protein to inhibit Gαs activity in a hormone-selective manner. We tested whether the GNAS exon A/B-derived NH2-terminally truncated (Tr) αs protein alters stimulation of adenylate cyclase by the PTH receptor (PTHR1), the thyroid-stimulating hormone (TSH) receptor (TSHR), the β2-adrenergic receptor (β2AR), or the AVP receptor (V2R). HEK293 cells cotransfected with receptor and full-length (FL) Gαs ± Tr αs protein expression vectors were stimulated with agonists (PTH [10−7 to 10−9 M], TSH [1 to 100 mU], isoproterenol [10−6 to 10−8 M], or AVP [10−6 to 10−8 M]). Following PTH stimulation, HEK293 cells cotransfected with PTHR1 + FL Gαs + Tr αs had a significantly lower cAMP response than those transfected with only PTHR1 + FL Gαs. Tr αs also exerted an inhibitory effect on the cAMP levels stimulated by TSH via the TSHR but had little or no effect on isoproterenol or AVP acting via β2AR or V2R, respectively. These differences mimic the spectrum of hormone resistance in pseudohypoparathyroidism type 1a (PHP-1a) and type 1b (PHP-1b) patients. In opossum kidney (OK) cells, endogenously expressing the PTHR1 and β2AR, the exogenous expression of Tr αs at a level similar to endogenous FL Gαs resulted in blunting of the cAMP response to PTH, whereas that to isoproterenol was unaltered. A pseudopseudohypoparathyroid patient with Albright hereditary osteodystrophy harbored a de novo paternally inherited M1I Gαs mutation. Similar maternally inherited mutations at the initiation codon have been identified previously in PHP-1a patients. The M1I αs mutant (lacking the first 59 amino acids of Gαs) blunted the increase in cAMP levels stimulated via the PTHR1 in both HEK293 and OK cells similar to the Tr αs protein. Thus NH2-terminally truncated forms of Gαs may contribute to the pathogenesis of pseudohypoparathyroidism by inhibiting the activity of Gαs itself in a GPCR selective manner. © 2011 American Society for Bone and Mineral Research
Vitamin D supplementation during pregnancy: Double-blind, randomized clinical trial of safety and effectiveness
Authors: Hollis Bruce W , Johnson Donna , Hulsey Thomas C , Ebeling Myla , Wagner Carol L
Published: June 2011

The need, safety, and effectiveness of vitamin D supplementation during pregnancy remain controversial. In this randomized, controlled trial, women with a singleton pregnancy at 12 to 16 weeks' gestation received 400, 2000, or 4000 IU of vitamin D3 per day until delivery. The primary outcome was maternal/neonatal circulating 25-hydroxyvitamin D [25(OH)D] concentration at delivery, with secondary outcomes of a 25(OH)D concentration of 80 nmol/L or greater achieved and the 25(OH)D concentration required to achieve maximal 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] production. Of the 494 women enrolled, 350 women continued until delivery: Mean 25(OH)D concentrations by group at delivery and 1 month before delivery were significantly different (p < 0.0001), and the percent who achieved sufficiency was significantly different by group, greatest in 4000-IU group (p < 0.0001). The relative risk (RR) for achieving a concentration of 80 nmol/L or greater within 1 month of delivery was significantly different between the 2000- and the 400-IU groups (RR = 1.52, 95% CI 1.24–1.86), the 4000- and the 400-IU groups (RR = 1.60, 95% CI 1.32–1.95) but not between the 4000- and. 2000-IU groups (RR = 1.06, 95% CI 0.93–1.19). Circulating 25(OH)D had a direct influence on circulating 1,25(OH)2D3 concentrations throughout pregnancy (p < 0.0001), with maximal production of 1,25(OH)2D3 in all strata in the 4000-IU group. There were no differences between groups on any safety measure. Not a single adverse event was attributed to vitamin D supplementation or circulating 25(OH)D levels. It is concluded that vitamin D supplementation of 4000 IU/d for pregnant women is safe and most effective in achieving sufficiency in all women and their neonates regardless of race, whereas the current estimated average requirement is comparatively ineffective at achieving adequate circulating 25(OH)D concentrations, especially in African Americans. © 2011 American Society for Bone and Mineral Research
Reaction rate of propene pyrolysis
Authors: Han Peipei , Su Kehe , Liu Yan , Wang Yanli , Wang Xin , Zeng Qingfeng , Cheng Laifei , Zhang Litong
Published: June 2011

The reaction rate of propene pyrolysis was investigated based on the elementary reactions proposed in Qu et al., J Comput Chem 2009, 31, 1421. The overall reaction rate was developed with the steady‐state approximation and the rate constants of the elementary reactions were determined with the variational transition state theory. For the elementary reaction having transition state, the vibrational frequencies of the selected points along the minimum energy path were calculated with density functional theory at B3PW91/6‐311G(d,p) level and the energies were improved with the accurate model chemistry method G3(MP2). For the elementary reaction without transition state, the frequencies were calculated with CASSCF/6‐311G(d,p) and the energies were refined with the multireference configuration interaction method MRCISD/6‐311G(d,p). The rate constants were evaluated within 200–2000 K and the fitted three‐parameter expressions were obtained. The results are consistent with those in the literatures in most cases. For the overall rate, it was found that the logarithm of the rate and the reciprocal temperature have excellent linear relationship above 400 K, predicting that the rate follows a typical first‐order law at high temperatures of 800–2000 K, which is also consistent with the experiments. The apparent activation energy in 800–2000 K is 317.3 kJ/mol from the potential energy surface of zero Kelvin. This value is comparable with the energy barriers, 365.4 and 403.7 kJ/mol, of the rate control steps. However, the apparent activation energy, 215.7 kJ/mol, developed with the Gibbs free energy surface at 1200 K is consistent with the most recent experimental result 201.9 ± 0.6 kJ/mol. © 2011 Wiley Periodicals, Inc. J Comput Chem, 2011
Rapid evaluation of the binding energies between peptide amide and DNA base
Authors: Li Yang , Wang Chang‐Sheng
Published: June 2011

The binding energies and the equilibrium hydrogen bond distances as well as the potential energy curves of 20 hydrogen‐bonded amide–base dimers are evaluated from the analytic potential energy function established in our laboratory recently. The analytic potential energy function is used to calculate the NH···N, NH···OC, CH···N, and CH···OC dipole–dipole attractive interaction energies and CO···OC, NH···HN, and NH···HC dipole–dipole repulsive interaction energies in the 20 dimers composed of DNA bases adenine, guanine, cytosine, or thymine and peptide amide. The calculation results show that the potential energy curves obtained from the analytic potential energy function are in good agreement with those obtained from MP2/6‐311+G** calculations by including the basis set superposition error (BSSE) correction. For all the 20 dimers, the analytic potential energy function yields the binding energies of the MP2/6‐311+G** with BSSE correction within the error limits of 0.50 kcal/mol for 19 dimers, only one difference is larger than 0.50 kcal/mol and the difference is only 0.61 kcal/mol. The analytic potential energy function produces the equilibrium hydrogen bond distances of the MP2/6‐311+G** with BSSE correction within the error limits of 0.030 Å for all the 20 dimers. The analytic potential energy function is further applied to four more complicated DNA base‐peptide amide systems involving amino acid side chain and β‐sheet. The values of the binding energies and equilibrium hydrogen bond distances obtained from the analytic potential energy function are also in good agreement with those obtained from MP2 calculations with the BSSE correction. These results demonstrate that the analytic potential energy function can be used to evaluate the binding energies in hydrogen‐bonded peptide amide–DNA base dimers quickly and accurately. © 2011 Wiley Periodicals, Inc. J Comput Chem, 2011
Importance of CH/π hydrogen bonds in recognition of the core motif in proline‐recognition domains: An Ab initio fragment molecular orbital study
Authors: Ozawa Tomonaga , Okazaki Kosuke , Kitaura Kazuo
Published: June 2011

We examined CH/π hydrogen bonds in protein/ligand complexes involving at least one proline residue using the ab initio fragment molecular orbital (FMO) method and the program CHPI. FMO calculations were carried out at the Hartree–Fock (HF)/6‐31G*, HF/6‐31G**, second‐order Møller–Plesset perturbation (MP2)/6‐31G*, and MP2/6‐31G** levels for three Src homology 3 (SH3) domains and five proline‐recognition domains (PRDs) complexed with their corresponding ligand peptides. PRDs use a conserved set of aromatic residues to recognize proline‐rich sequences of specific ligands. Many CH/π hydrogen bonds were identified in these complexes. CH/π hydrogen bonds occurred, in particular, in the central part of the proline‐rich motifs. Our results suggest that CH/π hydrogen bonds are important in the recognition of SH3 and PRDs by their ligand peptides and play a vital role in the signal transduction system. Combined use of the FMO method and CHPI analysis is a valuable tool for the study of protein/protein and protein/ligand interactions and may be useful in rational drug design. © 2011 Wiley Periodicals, Inc. J Comput Chem 2011