bluuebunny/crossref_metadata_2025 huggingface dataset:
Analysis of 5‐methyltetrahydrofolate in human blood, serum and urine by on‐line coupling of capillary isotachophoresis and zone electrophoresis
Authors: Pantůčková Pavla , Křivánková Ludmila
Published: September 2010

The predominant circulating folate coenzyme in plasma/serum, 5‐methyltetrahydrofolate (5‐MTHF) was determined in human blood, serum and urine using a method based on the hyphenation of capillary ITP and zone electrophoresis. Measurements were done with a commercially available instrument for capillary isotachophoresis equipped with a column‐switching system. The choice of electrolytes was limited by the instability of 5‐MTHF and volatility of electrolytes for the potential coupling of the instrumentation with MS detector. To get an insight into the separability of individual sample components in an isotachophoretic analysis, we constructed zone existence diagrams for isotachophoretic electrolyte systems having a leading electrolyte composed of acetate and ammonium of pH 4.5 and 7.0, hydrocarbonate and ammonium, pH 7.8, chloride and ammonium, pH 5.6, and chloride and creatinine, pH 5.0, with hydroxide ion as the terminator. For isotachophoretic preseparation, the non‐volatile leading electrolyte with good buffering capacity composed of 1×10−2 M HCl and 2.5×10−2 M creatinine, pH 5.0, and terminating electrolyte composed of 1×10−2 M MES was selected as the most suitable. The optimum BGE for CZE analysis from the standpoint of analyte stability, separability and volatility for MS coupling was 1×10−2 M acetate with 3.5×10−2 M ammonium, pH 4.5. Using this combination of electrolytes, LODs reached with optical detection at 220 nm were 1.6×10−7 M in human blood, 1.1×10−7 M in human serum and 4.7×10−6 M in human urine. Estimated content of 5‐MTHF in blood and serum samples of women following oral daily administration of 0.8 mg of folic acid was 1.2×10−5 and 5.8×10−6 M, respectively.
CE‐ESI‐MS coupled with dynamic pH junction online concentration for analysis of peptides in human urine samples
Authors: Ye Hongzhi , Xia Shifei , Lin Wei , Yu Lishuang , Xu Xueqin , Zheng Chunsong , Liu Xianxiang , Chen Guonan
Published: September 2010

In this article, an approach has been developed for the analysis of some small peptides with similar pI values by CE‐ESI‐MS based on the online concentration strategy of dynamic pH junction. The factors affected on the separation, detection and online enrichment, such as BGE, injection pressure, sheath flow liquid and separation voltage have been investigated in detail. Under the optimum conditions, i.e. using 0.5 mol/L formic acid (pH 2.15) as the BGE, preparing the sample in 50 mM ammonium acetate solution (pH 7.5), 50 mbar of injection pressure for 300 s, using 7.5 mM of acetic acid in methanol–water (80% v/v) solution as the sheath flow liquid and 20 kV as the separation voltage, four peptides with similar pI values, such as L‐Ala‐L‐Ala (pI=5.57), L‐Leu‐D‐Leu (pI=5.52), Gly‐D‐Phe (pI=5.52) and Gly‐Gly‐L‐Leu (pI=5.52) achieved baseline separation within 18.3 min with detection limits in the range of 0.2–2.0 nmol/L. RSDs of peak migration time and peak area were in the range of 1.45–3.57 and 4.93–6.32%, respectively. This method has been applied to the analysis of the four peptides in the spiked urine sample with satisfactory results.
An expanding negative detection method for the visualization of DNA in polyacrylamide gels by eosin Y
Authors: Zhu Zhong‐Xin , Cong Wei‐Tao , Zhang Peng‐Hui , Ma Wei‐De , Min Liu , He Hong‐Zhang , Choi Jung‐Kap , Jin Li‐Tai , Li Xiao‐Kun
Published: September 2010

A sensitive and easy technique has been developed for the negative detection of DNA following PAGE using eosin Y. After electrophoresis, gels are fixed and stained within 40 min to provide a detection limit of 0.1–0.2 ng of single DNA band, which appears as transparent and colorless under the opaque gel matrix background. The sensitivity of the new stain is fourfold better than zinc‐imidazole negative and ethidium bromide stains. Furthermore, the newly developed staining method has been successfully applied to RNA visualization in polyacrylamide gels. In addition, the inclusion of inorganic salts in staining solution was also investigated, which has great effect on the staining efficiency.
An integrated on‐chip sirtuin assay
Authors: Ohla Stefan , Beyreiss Reinhild , Scriba Gerhard K. E. , Fan Yi , Belder Detlev
Published: September 2010

A microchip‐based assay to monitor the conversion of peptide substrates by human recombinant sirtuin 1 (hSIRT1) is presented. For this purpose a fused silica microchip consisting of a microfluidic separation structure with an integrated serpentine micromixer has been used. As substrate for the assay, we used a 9‐fluorenylmethoxycarbonyl (Fmoc)‐labeled tetrapeptide derived from the amino acid sequence of p53, a known substrate of hSIRT1. The Fmoc group at the N‐terminus resulting from solid‐phase peptide synthesis enabled deep UV laser‐induced fluorescence detection with excitation at 266 nm. The enzymatic reaction of 0.1 U/μL hSIRT1 was carried out within the serpentine micromixer using a 400 μM solution of the peptide in buffer. In order to reduce protein adsorption, the reaction channel was dynamically coated with hydroxypropylmethyl cellulose. The substrate and the deacetylated product were separated by microchip electrophoresis on the same chip. The approach was successfully utilized to screen various SIRT inhibitors.
Capillary electrophoresis of the proteolytic activity of the stratum corneum obtained by tape stripping
Authors: Papoiu Alexandru D. P. , Yosipovitch Gil , Shihabi Zak
Published: September 2010

Serine proteases and some cathepsins are present in the stratum corneum. They are known to play a significant role in the pathophysiological mechanism of several dermatological conditions (e.g.atopic dermatitis) and in the induction of itch. Tape stripping of skin is a simple technique used in the investigation of skin barrier function and in the penetration of topically applied drugs. Herein, we show that CE, under stacking conditions, is a well‐suited technique to measure the proteolytic activity of enzymes in the stratum corneum. Disks of about 6 mm (id) were cut from adhered tapes and submerged directly in a buffer containing the appropriate peptide substrate. After incubation, the split peptides were separated and detected directly by CE at 214 nm in a borate buffer. The esterase activity onN‐benzoyl‐tyrosine ethyl ester and the amidase activity on succinyl‐Ala‐Ala‐Pro‐Phe‐p‐nitroanilide and the splitting of hemoglobin were detected by CE. The esterase activity was the highest when compared to the proteolytic activities. Skin scratching increased the enzymatic activity adhered to the tapes. The CE offered over the traditional end‐point colorimetric methods the ability to measure the low enzymatic activity and the ability to detect the released peptides directly. This technique is simple, non‐invasive, easy to perform and uses non‐expensive substrates. It can be useful in quantifying cathepsins and serine proteases in the skin.
Multi‐walled carbon nanotube composites with polyacrylate prepared for open‐tubular capillary electrochromatography
Authors: Chen Jian‐Lian , Lu Te‐Ling , Lin Yi‐Chen
Published: September 2010

A new phase containing immobilized carbon nanotubes (CNTs) was synthesized by in situ polymerization of acid‐treated multi‐walled CNTs using butylmethacrylate (BMA) as the monomer and ethylene dimethacrylate as the crosslinker on a silanized capillary, forming a porous‐layered open‐tubular column for CEC. Incorporation of CNT nanomaterials into a polymer matrix could increase the phase ratio and take advantage of the easy preparation of an OT‐CEC column. The completed BMA‐CNT column was characterized by SEM, ATR‐IR, and EOF measurements, varying the pH and the added volume organic modifier. In the multi‐walled CNTs structure, carboxylate groups were the major ionizable ligands on the phase surface exerting the EOF having electroosmotic mobility, 4.0×104 cm2 V−1 S−1, in the phosphate buffer at pH 2.8 and RSD values (n=5), 3.2, 4.1, and 4.3%, for three replicate capillaries at pH 7.6. Application of the BMA‐CNT column in CEC separations of various samples, including nucleobases, nucleosides, flavonoids, and phenolic acids, proved satisfactory upon optimization of the running buffers. Their optima were found in the borate buffers at pH 9.0/50 mM, pH 9.5/10 mM/50% v/v ACN, and pH 9.5/30 mM/10% v/v methanol, respectively. The separations could also be used to assess the relative contributions of electrophoresis and chromatography to the CEC mechanism by calculating the corresponding velocity and retention factors. Discussions about interactions between the probe solutes and the bonded phase included the π–π interactions, electrostatic repulsion, and hydrogen bonding. Furthermore, a reversed‐phase mode was discovered to be involved in the chromatographic retention.
Statistical evaluation of CZE‐UV and CZE‐ESI‐MS data of intact α‐1‐acid glycoprotein isoforms for their use as potential biomarkers in bladder cancer
Authors: Ongay Sara , Martín‐Álvarez Pedro J. , Neusüß Christian , de Frutos Mercedes
Published: September 2010

α‐1‐acid glycoprotein (AGP) is a highly heterogeneous protein that presents a vast number of isoforms (molecules of the protein differing in its peptidic and/or glycosidic moieties). In the last years, several authors have studied the potential use of AGP as a cancer biomarker. These studies focus on the correlation of different features of AGP structure (i.e. fucosylation, antennarity) with cancer or on the total protein blood concentration. In this study, the potential of CZE‐UV and CZE‐ESI‐MS analysis of intact AGP isoforms to study the correlation of this protein with bladder cancer is shown. Samples from 16 individuals (eight healthy, eight bladder cancer) were analyzed and characterized in great detail including data on intact protein isoforms and on released glycans. The analytical data were evaluated employing different statistical techniques (ANOVA; principal component analysis, PCA; linear discriminant analysis; and partial least squares‐discriminant analysis). Statistical differences between the two groups of study were observed. The best results were obtained by linear discriminant analysis of the CZE‐ESI‐MS data for intact AGP isoforms (93.75% of correct classification). Due to MS characterization, it can be observed that differences between the samples are mainly due to higher abundance of AGP isoforms containing tri‐ and tetra‐antennary fucosylated oligosaccharides in cancer patients. The results show the great potential of CE‐MS in combination with advanced data processing for the use of intact protein isoforms as disease biomarkers.
Use of organic solvent to prevent protein adsorption in CE‐MS experiments
Authors: Staub Aline , Comte Sylvain , Rudaz Serge , Veuthey Jean‐Luc , Schappler Julie
Published: September 2010

Protein adsorption onto capillary wall often hampers CE separations, particularly in the CZE mode. Electrostatic interactions are not the only factors affecting adsorption, as hydrophobic interactions and/or protein conformational changes are also involved in the adsorption phenomenon. Numerous methods can be used to reduce or avoid adsorption, such as (i) addition of low molecular weight molecules in the BGE, (ii) use of surfactants, or (iii) capillary coatings. However, most of these methods are not MS‐compatible. In this study, we evaluated the addition of organic solvent as an alternative MS‐compatible method to decrease protein adsorption. The effect of the solvent addition was emphasized using classical methods for estimating reversible and irreversible adsorption. In many cases, organic solvents were effective at decreasing adsorption. However, the influence of the organic solvent on protein adsorption should be evaluated case‐by‐case in CE method development.
An automated capillary electrophoresis system for high‐speed separation of DNA fragments based on a short capillary
Authors: Cheng Yong‐Qiang , Yao Bo , Zhang Hui‐Dan , Fang Jin , Fang Qun
Published: September 2010

A high‐speed DNA fragment separation system was developed based on a short capillary and a slotted‐vial array automated sample introduction system. The injection process of DNA sample in a short capillary was investigated systematically with three injection techniques including constant‐field‐strength, low‐field‐strength and translational spontaneous injections. Under the optimized conditions, picoliter‐scale sample plugs (corresponding to ca. 20‐μm plug length) were obtained, which ensure the high‐speed and high‐efficiency separation for DNA fragments with a short effective separation length. Other separation conditions including the sieving matrix concentration, separation field strength and effective separation length were also optimized. The present system was applied in the separation of ΦX174‐Hae III digest DNA marker. With an effective separation length of 2.5 cm, the separation could be achieved in <100 s with plate heights ranging from 0.21 to 0.74 μm (corresponding to plate numbers from 4.86×106 to 1.36×106/m). The repeatabilities for the migration time of the eleven fragments were between 0.4 and 1.1% RSD (n=8). By using the automated continuous injection method, the separation for four different DNA samples could be achieved within 250 s. The present system was further applied in the fast sizing of real DNA samples of PCR products.
Fairness‐aware user selection and resource allocation in MISO‐OFDMA
Authors: Papoutsis Vasileios D. , Fraimis Ioannis G. , Kotsopoulos Stavros A.
Published: September 2010

The problem of user selection and resource allocation for the downlink of wireless systems operating over a frequency‐selective channel is investigated. It is assumed that the Base Station (BS) uses many antennas, whereas a single antenna is available to each user (Multiple Input Single Output—MISO case). To relieve heavy computational burden, a suboptimal, but efficient algorithm is devised that is based on Zero Forcing (ZF) beamforming and is less complex than other approaches. The algorithm maximises the sum of the users' data rates subject to constraints on total available power and proportional fairness among users' data rates. Simulation results are provided to indicate that the algorithm can satisfy the fairness criterion. Thus, the algorithm can be applied to latest‐generation wireless systems that provide Quality‐of‐Service (QoS) guarantees. Copyright © 2010 John Wiley & Sons, Ltd.
Gender does not moderate hippocampal volume deficits in adults with posttraumatic stress disorder: A meta‐analysis
Authors: Woon Fu , Hedges Dawson W.
Published: September 2010

Epidemiological studies show a higher point prevalence of posttraumatic stress disorder (PTSD) in women than in men, and early evidence has suggested that gender may moderate hippocampal volume deficits in PTSD. Our objective was to use random‐effects meta‐regression to assess gender effects on hippocampal volume deficits in PTSD. Using the terms posttraumatic stress disorder, gender, MRI, hippocampus, trauma, and abuse, we searched electronic databases for peer‐reviewed articles up to April 2009 containing data for hippocampal volume and gender composition in PTSD adults compared with controls. We identified 23 studies that met inclusion criteria and calculated effect sizes for differences in hippocampal mean volumes for each study and used the percentage of men with PTSD as a continuous moderating variable in meta‐regression. Additionally, we did a subgroup analysis of hippocampal volume deficits between women and men with gender as a categorical moderating variable. Hippocampal volumes were significantly smaller in the PTSD group compared to the control group, but gender did not significantly moderate any effect sizes in the meta‐regression or subgroup analyses. The lack of gender moderation on hippocampal volume deficits suggests that hippocampal volume deficits in PTSD are independent of gender. The higher prevalence of PTSD in females than in males does not correspond to increased hippocampal volume deficits in women with PTSD compared to men with PTSD, and neither gender appears protective against hippocampal volume deficits in adults with PTSD. © 2011 Wiley‐Liss, Inc.
The effects of selective hippocampal damage on tests of oddity in rhesus macaques
Authors: Alvarado Maria C. , Kazama Andy , Zeamer Alyson , Bachevalier Jocelyne
Published: September 2010

The oddity task (e.g., A−, A−, B+) is classified as a conjunctive or relational task in which accurate performance depends upon learning to attend to stimulus relationships, not stimulus identity, and has no retention component as stimuli are presented simultaneously. It has been suggested that the hippocampus may play a particular role in learning this type of task in humans and animals. To test this, we trained adult rhesus macaques with selective neurotoxic damage to the hippocampal formation on their ability to learn and apply an oddity rule. The results suggest that the monkeys were able to adapt simple strategies to solve variations of the oddity task, however as the opportunity for such strategies was reduced, monkeys with hippocampal damage were increasingly impaired. © 2010 Wiley‐Liss, Inc.
Dissociations within human hippocampal subregions during encoding and retrieval of spatial information
Authors: Suthana Nanthia , Ekstrom Arne , Moshirvaziri Saba , Knowlton Barbara , Bookheimer Susan
Published: September 2010

Although the hippocampus is critical for the formation and retrieval of spatial memories, it is unclear how subregions are differentially involved in these processes. Previous high‐resolution functional magnetic resonance imaging (fMRI) studies have shown that CA2, CA3, and dentate gyrus (CA23DG) regions support the encoding of novel associations, whereas the subicular cortices support the retrieval of these learned associations. Whether these subregions are used in humans during encoding and retrieval of spatial information has yet to be explored. Using high‐resolution fMRI (1.6 mm × 1.6‐mm in‐plane), we found that activity within the right CA23DG increased during encoding compared to retrieval. Conversely, right subicular activity increased during retrieval compared to encoding of spatial associations. These results are consistent with the previous studies illustrating dissociations within human hippocampal subregions and further suggest that these regions are similarly involved during the encoding and retrieval of spatial information. © 2010 Wiley‐Liss, Inc.
Components of recognition memory: Dissociable cognitive processes or just differences in representational complexity?
Authors: Cowell Rosemary A. , Bussey Timothy J. , Saksida Lisa M.
Published: September 2010

Many current theoretical views within the literature on recognition memory—a representative sample of which is provided by the present special issue—advocate the dissociation of recognition memory into two cognitive processes: familiarity‐based recognition, and recollection/recall. Furthermore, these processes are proposed to be mediated by distinct and dissociable anatomical regions, usually the perirhinal cortex and hippocampus, respectively. In this article, we describe a representational‐hierarchical view that provides an account of cognition, including mnemonic and perceptual processing, within a brain pathway we term the ventral visual‐perirhinal‐hippocampal stream. According to this view cognition, perception, memory, and indeed amnesia may be understood by considering the content and organization of stimulus representations in the brain. Taking this view leads us to question the idea of cognitive modules for introspectively derived notions such as familiarity and recollection. We begin by reviewing the representational‐hierarchical framework, explain how it has been used to account for object recognition memory in perirhinal cortex, and review the rationale for extending this framework to the hippocampus. We then discuss whether the principles of the representational‐hierarchical framework can be used to understand recollection and familiarity in terms of stimulus complexity, and use these principles to reconsider some of the evidence for neuroanatomical, dual‐process models of recognition memory. © 2010 Wiley‐Liss, Inc.
Changes in the two‐dimensional electrophoresis pattern of the Parkinson's disease related protein DJ‐1 in human SH‐SY5Y neuroblastoma cells after dopamine treatment
Authors: Alberio Tiziana , Colapinto Monica , Natale Massimo , Ravizza Raffaella , Gariboldi Marzia B. , Bucci Enrico M. , Lopiano Leonardo , Fasano Mauro
Published: September 2010

Changes in the Two‐Dimensional Electrophoresis Pattern of the Parkinson's Disease Related Protein DJ‐1 in Human SH‐SY5Y Neuroblastoma Cells After Dopamine Treatment by Tiziana Alberio, Monica Colapinto, Massimo Natale, Raffaella Ravizza, Marzia B. Gariboldi, Enrico M. Bucci, Leonardo Lopiano, and Mauro Fasano, pp. 688–692.
Steric effects on alkyl cation affinities of maingroup‐element hydrides
Authors: Ruiz Juan M. , Mulder R. Joshua , Guerra Célia Fonseca , Bickelhaupt F. Matthias
Published: September 2010

We have carried out an extensive exploration of gas‐phase alkyl cation affinities (ACA) of archetypal anionic and neutral bases across the periodic system using zeroth order regular approximation‐relativistic density functional theory at BP86/QZ4P//BP86/TZ2P. ACA values were computed for the methyl, ethyl, i‐propyl and t‐butyl cations and compared with the corresponding proton affinities (PA). One purpose of this work is to provide an intrinsically consistent set of values of the 298 K ACA of all anionic (XH) and neutral bases (XHn) constituted by maingroup‐element hydrides of groups 14–17 and the noble gases (group 18) along the periods 1–6. Another purpose is to determine and rationalize the trend in affinity for a cation as the latter varies from proton to t‐butyl cation. This undertaking is supported by quantitative bond energy decomposition analyses. Correlations are established between PA and ACA values. © 2010 Wiley Periodicals, Inc. J Comput Chem, 2011
Exponential bounds on the number of designs with affine parameters
Authors: Clark David , Jungnickel Dieter , Tonchev Vladimir D.
Published: September 2010

It is well‐known that the number of designs with the parameters of a classical design having as blocks the hyperplanes in PG(n, q) or AG(n, q), n≥3, grows exponentially. This result was extended recently [D. Jungnickel, V. D. Tonchev, Des Codes Cryptogr, published online: 23 May, 2009] to designs having the same parameters as a projective geometry design whose blocks are the d‐subspaces of PG(n, q), for any 2≤d≤n−1. In this paper, exponential lower bounds are proved on the number of non‐isomorphic designs having the same parameters as an affine geometry design whose blocks are the d‐subspaces of AG(n, q), for any 2≤d≤n−1, as well as resolvable designs with these parameters. An exponential lower bound is also proved for the number of non‐isomorphic resolvable 3‐designs with the same parameters as an affine geometry design whose blocks are the d‐subspaces of AG(n, 2), for any 2≤d≤n−1. © 2010 Wiley Periodicals, Inc. J Combin Designs 18: 475–487, 2010
Automatic method for tracing regions of interest in rat brain magnetic resonance imaging studies
Authors: Nie Binbin , Hui Jiaojie , Wang Lijing , Chai Pei , Gao Juan , Liu Shuangquan , Zhang Zhijun , Shan Baoci , Zhao Shujun
Published: September 2010

Purpose

To automatically extract regions of interest (ROIs) and simultaneously preserve the anatomical characteristics of each individual, we developed a new atlas‐based method utilizing a pair of coregistered brain template and digital atlas.

Materials and Methods

Unlike the previous atlas‐based method, this method treats each individual as the target image, and the template and atlas are each transformed to register with the individual. To evaluate the accuracy of this method we implemented it in extracting the hippocampus from two groups of T2‐weighted structural images with different spatial resolutions and a group of T2*‐weighted functional images. Furthermore, the results were compared against a manually segmented hippocampus and an atlas‐derived hippocampus.

Results

Jaccard similarity (JS) reached 84.7%–90.5%, and relative error in volume (RV) was 4.8%–12.7%. The consistency observed between the results of the proposed method and manual drawing was therefore considerable.

Conclusion

We developed a new atlas‐based method for ROI extraction that can automatically extract ROI and simultaneously preserve each individual's unique anatomical characteristics. J. Magn. Reson. Imaging 2010;32:830–835. © 2010 Wiley‐Liss, Inc.
Percent infarct mapping for delayed contrast enhancement magnetic resonance imaging to quantify myocardial viability by Gd(DTPA)
Authors: Simor Tamás , Surányi Pál , Ruzsics Balázs , Tóth Attila , Tóth Levente , Kiss Pál , Brott Brigitta C. , Varga‐Szemes Ákos , Elgavish Ada , Elgavish Gabriel A.
Published: September 2010

Purpose

To demonstrate the advantages of signal intensity percent‐infarct‐mapping (SI‐PIM) using the standard delayed enhancement (DE) acquisition in assessing viability following myocardial infarction (MI). SI‐PIM quantifies MI density with a voxel‐by‐voxel resolution in clinically used DE images.

Materials and Methods

In canines (n= 6), 96 hours after reperfused MI and administration of 0.2 mmol/kg Gd(DTPA), ex vivo DE images were acquired and SI‐PIMs calculated. SI‐PIM data were compared with data from DE images analyzed with several thresholding levels using SIremote+2SD, SIremote+6SD, SI full width half maximum (SIFWHM), and with triphenyl‐tetrazolium‐chloride (TTC) staining. SI‐PIM was also compared to R1 percent infarct mapping (R1‐PIM).

Results

Left ventricular infarct volumes (IV) in DE images, IVSIremote+2SD and IVSIremote+6SD, overestimated (P < 0.05) TTC by medians of 13.21 mL [10.2; 15.2] and 6.2 mL [3.79; 8.23], respectively. SIFWHM, SI‐PIM, and R1‐PIM, however, only nonsignificantly underestimated TTC, by medians of −0.10 mL [−0.12, −0.06], −0.86 mL [−1.04; 1.54], and −1.30 mL [−4.99; −0.29], respectively. The infarct‐involved voxel volume (IIVV) of SI‐PIM, 32.4 mL [21.2, 46.3] is higher (P < 0.01) than IIVVs of SIFWHM 8.3 mL [3.79, 19.0]. SI‐PIMFWHM, however, underestimates TTC (−5.74 mL [−11.89; −2.52] (P < 0.01)). Thus, SI‐PIM outperforms SIFWHM because larger IIVVs are obtained, and thus PIs both in the rim and the core of the infarcted tissue are characterized, in contradistinction from DE‐SIFWHM, which shows mainly the infarct core.

Conclusion

We have shown here, ex vivo, that SI‐PIM has the same advantages as R1‐PIM, but it is based on the scanning sequences of DE imaging, and thus it is obtainable within the same short scanning time as DE. This makes it a practical method for clinical studies. J. Magn. Reson. Imaging 2010;32:859–868. © 2010 Wiley‐Liss, Inc.
Magnetic resonance imaging near metal implants
Authors: Koch K.M. , Hargreaves B.A. , Pauly K. Butts , Chen W. , Gold G.E. , King K.F.
Published: September 2010

The desire to apply magnetic resonance imaging (MRI) techniques in the vicinity of embedded metallic hardware is increasing. The soft‐tissue contrast available with MR techniques is advantageous in diagnosing complications near an increasing variety of MR‐safe metallic hardware. Near such hardware, the spatial encoding mechanisms utilized in conventional MRI methods are often severely compromised. Mitigating these encoding difficulties has been the focus of numerous research investigations over the past two decades. Such approaches include view‐angle tilting, short echo‐time projection reconstruction acquisitions, single‐point imaging, prepolarized MRI, and postprocessing image correction. Various technical advances have also enabled the recent development of two alternative approaches that have shown promising clinical potential. Here, the physical principals and proposed solutions to the problem of MRI near embedded metal are discussed. J. Magn. Reson. Imaging 2010;32:773–787. © 2010 Wiley‐Liss, Inc.
Fat‐water separation in dynamic objects using an UNFOLD‐like temporal processing
Authors: Ababneh Riad , Yuan Jing , Madore Bruno
Published: September 2010

Purpose

To separate fat and water signals in dynamic imaging. Because important features may be embedded in fat, and because fat may take part in disease processes, separating fat and water signals may be of great importance in a number of clinical applications. This work aims to achieve such separation at nearly no loss in temporal resolution compared to usual, nonseparated acquisitions. In contrast, the well‐known 3‐point Dixon method may cause as much as a 3‐fold reduction in temporal resolution.

Materials and Methods

The proposed approach involves modulating the echo time TE from frame to frame, to force fat signals to behave in a conspicuous manner through time, so they can be readily identified and separated from water signals. The strategy is inspired from the “unaliasing by Fourier encoding the overlaps in the temporal direction” (UNFOLD) method, although UNFOLD involves changes in the sampling function rather than TE, and aims at suppressing aliased material rather than fat.

Results

The method was implemented at 1.5 T and 3 T, on cardiac cine and multiframe steady‐state free precession sequences. In addition to phantom results, in vivo results from volunteers are presented.

Conclusion

Good separation of fat and water signals was achieved in all cases. J. Magn. Reson. Imaging 2010;32:962–970. © 2010 Wiley‐Liss, Inc.
Functional MRI of liver using BOLD MRI: Effect of glucose
Authors: Haque Muhammad , Koktzoglou Ioannis , Li Wei , Carbray JoAnn , Prasad Pottumarthi
Published: September 2010

Purpose

To demonstrate feasibility of functional MRI of liver using glucose as a stimulus to monitor metabolic changes using blood oxygenation level dependent (BOLD) contrast. We hypothesized that during hyperglycemia, liver stores the glucose and consequently there is a reduction in oxygen consumption, which can be detected using BOLD MRI.

Materials and Methods

In four mini pigs, measurements were made before and after 54 g of glucose administered intravenously. In six healthy young human subjects, measurements were made before and after oral ingestion of 75 g of glucose. T2* weighted images of the liver were obtained on a Siemens 3 Tesla Verio MRI scanner using multiple gradient recalled echo (mGRE) sequence.

Results

A statistically significant decrease (P < 0.05) in R2* (1/T2*) was observed postglucose both in swine (110.41 ± 14.1 s−1 to 72.22 ± 5.7 s−1) and human (55.84 ±3.8 s−1 to 50.6 ±0.5 s−1), suggesting improved liver oxygenation during hyperglycemia.

Conclusion

Our preliminary data presented here demonstrate the feasibility of obtaining functional liver images that illustrate the changes in oxygen consumption. Further studies are necessary to fully validate the technique. J. Magn. Reson. Imaging 2010;32:988–991. © 2010 Wiley‐Liss, Inc.
In vivo quantification of murine aortic cyclic strain, motion, and curvature: Implications for abdominal aortic aneurysm growth
Authors: Goergen Craig J. , Barr Kyla N. , Huynh Diem T. , Eastham‐Anderson Jeffrey R. , Choi Gilwoo , Hedehus Maj , Dalman Ronald L. , Connolly Andrew J. , Taylor Charles A. , Tsao Philip S. , Greve Joan M.
Published: September 2010

Purpose

To develop methods to quantify cyclic strain, motion, and curvature of the murine abdominal aorta in vivo.

Materials and Methods

C57BL/6J and apoE−/− mice underwent three‐dimensional (3D) time‐of‐flight MR angiography to position cardiac‐gated 2D slices at four locations along the abdominal aorta where circumferential cyclic strain and lumen centroid motion were calculated. From the 3D data, a centerline through the aorta was created to quantify geometric curvature at 0.1‐mm intervals. Medial elastin content was quantified with histology postmortem. The location and shape of abdominal aortic aneurysms (AAAs), created from angiotensin II infusion, were evaluated qualitatively.

Results

Strain waveforms were similar at all locations and between groups. Centroid motion was significantly larger and more leftward above the renal vessels than below (P < 0.05). Maximum geometric curvature occurred slightly proximal to the right renal artery. Elastin content was similar around the circumference of the vessel. AAAs developed in the same location as the maximum curvature and grew in the same direction as vessel curvature and motion.

Conclusion

The methods presented provide temporally and spatially resolved data quantifying murine aortic motion and curvature in vivo. This noninvasive methodology will allow serial quantification of how these parameters influence the location and direction of AAA growth. J. Magn. Reson. Imaging 2010;32:847–858. © 2010 Wiley‐Liss, Inc.
Improving proton MR spectroscopy of brain tissue for noninvasive diagnostics
Authors: Alusta Pierre , Im Inessa , Pearce Bruce A. , Beger Richard D. , Kretzer Ryan M. , Buzatu Dan A. , Wilkes Jon G.
Published: September 2010

Purpose

To examine preprocessing methods affecting the potential use of Magnetic Resonance Spectroscopy (MRS) as a noninvasive modality for detection and characterization of brain lesions and for directing therapy progress.

Materials and Methods

Two reference point re‐calibration with linear interpolation (to compensate for magnetic field nonhomogeneity), weighting of spectra (to emphasize consistent peaks and depress chemical noise), and modeling based on chemical shift locations of 97 biomarkers were investigated. Results for 139 categorized scans were assessed by comparing Leave‐One‐Out (LOO) cross‐validation and external validation.

Results

For distinction of nine brain tissue categories, use of re‐calibration, variance weighting, and biomarker modeling improved LOO classification of MRS spectra from 31% to 95%. External validation of the two best nine‐category models on 47 unknown samples gave 96% or 100% accuracy, respectively, compared with pathological diagnosis.

Conclusion

Preprocessing of MRS spectra can significantly improve their diagnostic utility for automated consultation of pattern recognition models. Use of several techniques in combination greatly increases available proton MRS information content. Accurate assignment of unknowns among nine tissue classes represents a significant improvement, for a much more demanding task, than has been previously reported. J. Magn. Reson. Imaging 2010;32:818–829. © 2010 Wiley‐Liss, Inc.
Neuron‐selective toxicity of tau peptide in a cell culture model of neurodegenerative tauopathy: Essential role for aggregation in neurotoxicity
Authors: Zhao Kelly , Ippolito Giulia , Wang Lulu , Price Valerie , Kim Mi Hwa , Cornwell Gavin , Fulenchek Stephanie , Breen Gail A. , Goux Warren J. , D'Mello Santosh R.
Published: September 2010

Intracellular aggregation of tau is a pathological hallmark in Alzheimer's disease and other tauopathies. The mechanisms underlying tau aggregation and the role that these aggregates play in neuronal death have remained controversial. To study these issues, we established a cell culture model of tauopathy using a hexameric peptide with the sequence 306VQIVYK311 located within the third microtubule‐binding repeat of tau, rendered cell‐permeable by a tag of nine arginine residues (R9). This peptide (VQIVYK‐R9), designated as T‐peptide, self‐assembles in vitro into paired helical filament‐like aggregates. Primary neuronal cells treated with T‐peptide die within 24 hr. Neurodegeneration correlates with the ability of the peptide to aggregate. Two peptides with mutations in the hexameric core, K‐peptide (VQIVKK) and VV‐peptide (VQVVVK), that are incapable of aggregating are not toxic, whereas two other mutant peptides, V‐peptide (VQVVYK) and F‐peptide (VQIVFK), which aggregate, are also neurotoxic. Two other peptides that aggregate in vitro, but are not derived from tau, are not neurotoxic suggesting sequence dependence. Although localizing to the nucleus, T‐peptide induces aggregation of cellular proteins in the cytoplasm. These aggregates are not caused by disruption of endogenous tau localization, although endogenous tau is reduced in neurons exposed to T‐peptide. Interestingly, nonneuronal cells are less sensitive to T‐peptide toxicity, recapitulating in part the selective lossof neurons in tauopathies. Moreover, T‐peptide treatment leads to mitochondrial dysfunction, a common feature of neurodegenerative disorders. The model system described here represents a convenient paradigm for studying the mechanisms underlying tau aggregation and neurotoxicity and for identifying compounds that can prevent these effects. © 2010 Wiley‐Liss, Inc.
Axon growth and guidance genes identify nascent, immature, and mature olfactory sensory neurons
Authors: McIntyre Jeremy C. , Titlow William B. , McClintock Timothy S.
Published: September 2010

Neurogenesis of projection neurons requires that axons be initiated, extended, and connected. Differences in the expression of axon growth and guidance genes must drive these events, but comprehensively characterizing these differences in a single neuronal type has not been accomplished. Guided by a catalog of gene expression in olfactory sensory neurons (OSNs), in situ hybridization and immunohistochemistry revealed that Cxcr4 and Dbn1, two axon initiation genes, marked the developmental transition from basal progenitor cells to immature OSNs in the olfactory epithelium. The CXCR4 immunoreactivity of these nascent OSNs overlapped partially with markers of proliferation of basal progenitor cells and partially with immunoreactivity for GAP43, the canonical marker of immature OSNs. Intracellular guidance cue signaling transcripts Ablim1, Crmp1, Dypsl2, Dpysl3, Dpysl5, Gap43, Marcskl1, and Stmn1–4 were specific to, or much more abundant in, the immature OSN layer. Receptors that mediate axonal inhibition or repulsion tended to be expressed in both immature and mature OSNs (Plxna1, Plxna4, Nrp2, Efna5) or specifically in mature OSNs (Plxna3, Unc5b, Efna3, Epha5, Epha7), although some were specific to immature OSNs (Plxnb1, Plxnb2, Plxdc2, Nrp1). Cell adhesion molecules were expressed either by both immature and mature OSNs (Dscam, Ncam1, Ncam2, Nrxn1) or solely by immature OSNs (Chl1, Nfasc1, Dscaml1). Given the loss of intracellular signaling protein expression, the continued expression of guidance cue receptors in mature OSNs is consistent with a change in the role of these receptors, perhaps to sending signals back to the cell body and nucleus. © 2010 Wiley‐Liss, Inc.
Predicting the effect of tray malalignment on risk for bone damage and implant subsidence after total knee arthroplasty
Authors: Wong Jowene , Steklov Nikolai , Patil Shantanu , Flores‐Hernandez Cesar , Kester Mark , Colwell Clifford W. , D'Lima Darryl D.
Published: September 2010

Tibial tray malalignment has been associated with increased subsidence and failure. We constructed a finite element model of knee arthroplasty to determine the biomechanical factors involved in increasing the risk of subsidence with malalignment. Four fresh‐frozen human knees were implanted with a tibial tray and subjected to forces representative of walking for up to 100,000 cycles. Cyclic displacement was measured between the tray and proximal tibia. The vertical load was shifted medially to generate a load distribution ratio of 55:45 (medial/lateral) to represent neutral alignment or 75:25 to represent varus alignment. Subjected specific geometry and material properties were obtained from qCT scans of tibia to construct a finite element model. The tray was subjected to a single load cycle representing experimental conditions. Tray displacement computed by the model matched that measured experimentally. Forces representing varus tray alignment generated greater strains in the proximal tibia and a greater volume of bone was subjected to strains higher than the fatigue threshold. Local compressive strains directly correlated with experimental subsidence and failure. Our results indicate that failure after tray malalignment is likely due to fatigue damage to the proximal tibia rather than shear across the implant–bone interface or failure of the cement mantle. © 2010 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 29:347–353, 2011
An injectable composite material containing bone morphogenetic protein‐2 shortens the period of distraction osteogenesis in vivo
Authors: Eguchi Yoshitaka , Wakitani Shigeyuki , Naka Yoshifumi , Nakamura Hiroaki , Takaoka Kunio
Published: September 2010

To investigate new methods that can decrease the duration of bone transport (BT) distraction osteogenesis, we injected composite materials containing recombinant human bone morphogenetic protein‐2 (BMP‐2) and induced the generation of a callus bridge by rapid segmental transport (4 mm/day) in a rabbit bone defect model. The composite materials consisted of BMP‐2 (0, 30, or 100 µg), β‐tricalcium phosphate powder (βTCP, 100 mg/animal; particle size, <100 µm), and polyethylene glycol (PEG; 40 mg/animal). A paste of equivalent composition was percutaneously injected at the lengthening and the docking sites after surgery and after BT, respectively. The radiographic, mechanical, and histological examinations 12 weeks post‐operative revealed that the generation of bridging callus in the presence and in the absence of BMP‐2 was significantly different. The callus mass in the bone defect region was adequately and consistently developed in the presence of 100 µg of BMP (administered for 6 weeks), and the bones were consolidated in 12 weeks. Such an adequate callus formation was not observed in the control animals without BMP‐2 treatment. The result of this experimental study suggests the potential application of BMP‐2 in accelerating callus formation and in enabling rapid bone transporting, thereby shortening the treatment period for the repair of diaphyseal bone defects by distraction osteogenesis. © 2010 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 29:452–456, 2011
Metaphyseal fracture healing follows similar biomechanical rules as diaphyseal healing
Authors: Claes Lutz , Reusch Martina , Göckelmann Melanie , Ohnmacht Michael , Wehner Tim , Amling Michael , Beil Frank T. , Ignatius Anita
Published: September 2010

It is generally supposed that the pattern of fracture healing in trabecular metaphyseal bone differs from that of diaphyseal fractures. However, few experimental studies to date have been performed, even though clinically many fractures occur in metaphyseal bone. Particularly, the influence of biomechanical factors has not yet been investigated under standardized conditions. Our aim was to correlate the interfragmentary strain (IFS) with the bone‐healing outcome in a controlled metaphyseal fracture model in sheep. Twelve sheep received a partial osteotomy in the distal femoral condyle close to the trochlea. The determination of the IFS by in vivo X‐ray analyses and a finite element model revealed that the deflection of the osteotomy gap by the patello‐femoral force during walking provoked increasing strains of up to 40%. Bone healing was evaluated after 8 weeks by the assessment of the bone mineral density and by histomorphometry in regions of interest that displayed differing magnitudes of IFS. In areas with strains below 5% significantly less bone formation occurred compared to areas with higher strains (6–20%). For strains larger than 20% fibrocartilage layers were observed. Low IFS (<5%) led to intramembranous bone formation, whereas higher strains additionally provoked endochondral ossification or fibrocartilage formation. It is therefore proposed that metaphyseal bone healing follows similar biomechanical principles as diaphyseal healing. © 2010 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 29:425–432, 2011
Hybrid polyacrylamide chiral stationary phases for HPLC prepared by surface‐initiated photopolymerization
Authors: Ciogli Alessia , D'Acquarica Ilaria , Gasparrini Francesco , Molinaro Carmela , Rompietti Romina , Simone Patrizia , Villani Claudio , Zappia Giovanni
Published: September 2010

Two hybrid polyacrylamide chiral stationary phases (CSPs) for HPLC have been synthesized by a new surface‐initiated photo‐induced radical polymerization approach of enantiopure N,N′‐diacryloyl derivatives of (1R,2R)‐diaminocyclohexane (CSP1) and (1R,2R)‐diphenylethylenediamine (CSP2). This system is based on the activation of mesoporous silica microparticles by chemically bonded trichloroacetyl groups and dimanganese decacarbonyl as catalyst. UV irradiation was performed using a lab‐made quartz photochemical reactor, ad hoc designed for the photo‐induced polymerization process on the surface of microparticles. The two phases were evaluated and compared as chromatographic supports for the enantioselective HPLC of model chiral compounds. Their physico‐chemical properties and chromatographic performances were also evaluated in comparison with those exhibited by the homologue CSPs obtained by the grafting‐from thermal‐induced process (CSP3 and CSP4). The new photopolymerization approach yielded higher grafting density than the thermal‐induced one, especially in the case of the less reactive monomer (the diacryloyl derivative of (1R,2R)‐diphenylethylenediamine), good chromatographic efficiency and a broad application field under normal phase and polar organic mode conditions.
Comparison of Er:YAG laser and piezoelectric osteotomy: An animal study in sheep
Authors: Stübinger Stefan , Nuss Katja , Pongratz Michaela , Price Jill , Sader Robert , Zeilhofer Hans‐Florian , von Rechenberg Brigitte
Published: September 2010

Objectives

It was the aim of this study to compare the feasibility of complete osteotomy of long bones in sheep using a newly designed variable square pulsed Er:YAG laser and piezoelectric surgery. In addition to uneventful bone healing after laser osteotomy, the goal was to assess the possibility to cut thick bony structures with both techniques in a surgically acceptable time frame of 2–3 minutes.

Material and Methods

A tibia midshaft osteotomy was performed in 24 sheep using either an Er:YAG laser (n = 12) or piezoelectric device (n = 12). Laser and piezoelectric groups were divided in two subgroups (n = 6) with sheep sacrificed after 2 and 3 months, respectively. A complete radiological, histological and histomorphometric analysis was performed to compare the course of bone/fracture healing and remodelling.

Results

Laser and piezoelectric osteotomies of the sheep tibia up to a depth of 22 mm were possible without any thermal damage. Radiological and histological results after 2 months showed primary gap healing with distinct periosteal callus formation on the transcortex. After 3 months, radiological and histological analysis revealed less callus formation on the transcortex, with almost no visible osteotomy gap and a distinct formation of lamellar bone crossing the original osteotomy gap.

Conclusion

Er:YAG laser osteotomy can successfully be used in long bones with a depth of up to 22 mm, thus challenging the dogma of adverse effects of laser osteotomy due to thermal or other damages. Lasers Surg. Med. 42:743–751, 2010 © 2010 Wiley‐Liss, Inc.