bluuebunny/crossref_metadata_2025 huggingface dataset:
Chloride channel ClC‐3 promotion of osteogenic differentiation through Runx2
Authors: Wang Huan , Mao Yong , Zhang Bin , Wang Tao , Li Feifei , Fu Shanmin , Xue Yang , Yang Ting , Wen Xuan , Ding Yin , Duan Xiaohong
Published: April 2010

ClC‐3 chloride channel has been speculated to contribute to the acidification of synaptic vesicles and endosomes. However, the biological function of ClC‐3 in osteogenesis remains to be determined. In this study, we first analyzed ClC‐3 expression in MC3T3‐E1 cells and primary mouse osteoblasts and then performed the osteoinductive procedure to determine the effects on gene expression. Subsequently, we transiently transfected ClC‐3 cDNA or ClC‐3‐siRNA into MC3T3‐E1 cells to determine the changed phenotype and gene expression. Lastly, we assessed the underlying mechanism responsible for ClC‐3‐induced osteodifferentiation. We found that ClC‐3 mRNA was expressed in primary mouse osteoblasts and MC3T3‐E1 cells and induced by using an osteoinductive procedure. We also found that overexpression of ClC‐3 contributed to osteodifferentiation, such as increase in the expression of osteogenic markers [alkaline phosphatase (Alp), osteocalcin (Oc), bone sialoprotein (Bsp), osterix (Osx), and runt‐related transcription factor 2 (Runx2)], morphological changes, and mineralized nodules in MC3T3‐E1 cells. ClC‐3 gene silencing suppressed gene expression of these osteogenic markers. Moreover, overexpressed ClC‐3 protein co‐localized with TGF‐β1 in intracellular organelles, inhibited TGF‐β1 protein expression and induced endosomal acidification. Nevertheless, knockdown of Runx2 expression antagonized the effects of ClC‐3 in osteodifferentiation and expression of osteogenic markers. The data from the current study suggest that the function of ClC‐3 in osteodifferentiation may be through the Runx2 pathway. J. Cell. Biochem. 111: 49–58, 2010. © 2010 Wiley‐Liss, Inc.
The biology and pathology of vitamin D control in bone
Authors: Bell Taison D. , Demay Marie B. , Burnett‐Bowie Sherri‐Ann M.
Published: April 2010

Vitamin D is a steroid pro‐hormone, whose active metabolite binds the vitamin D receptor (VDR) which, in turn, binds to DNA sequences on target genes as a heterodimer with the retinoid‐X receptor, resulting in regulation of gene expression. The vitamin D pro‐hormone can be synthesized in the skin, in response to ultraviolet radiation; however, dietary sources have become increasingly important as a result of cultural changes over the past few centuries. Based on its initial discovery as an anti‐rachitic factor, studies of the role of vitamin D and its receptor have largely focused on the skeleton. Investigations into the pathophysiologic basis and therapeutic responses of skeletal disorders associated with impaired vitamin D action have led to the identification of the molecular pathways involved in hormone activation and regulation of gene expression by the liganded VDR. These studies have also demonstrated that the skeletal actions of the VDR and its ligand are largely redundant if normal mineral ion homeostasis can be maintained by other means. However, investigations in animal models with tissue‐specific ablation of the VDR or the enzyme required for hormone activation have demonstrated novel actions in skeletal tissues. The active vitamin D metabolite has been shown to have both paracrine and endocrine actions in other tissues as well. J. Cell. Biochem. 111: 7–13, 2010. © 2010 Wiley‐Liss, Inc.
Methionine sulfoxide reductase A (MsrA) protects cultured mouse embryonic stem cells from H2O2‐mediated oxidative stress
Authors: Zhang Chi , Jia Pingping , Jia Yuanyuan , Weissbach Herbert , Webster Keith A. , Huang Xupei , Lemanski Sharon L. , Achary Mohan , Lemanski Larry F.
Published: April 2010

Methionine sulfoxide reductase A (MsrA), a member of the Msr gene family, can reduce methionine sulfoxide residues in proteins formed by oxidation of methionine by reactive oxygen species (ROS). Msr is an important protein repair system which can also function to scavenge ROS. Our studies have confirmed the expression of MsrA in mouse embryonic stem cells (ESCs) in culture conditions. A cytosol‐located and mitochondria‐enriched expression pattern has been observed in these cells. To confirm the protective function of MsrA in ESCs against oxidative stress, a siRNA approach has been used to knockdown MsrA expression in ES cells which showed less resistance than control cells to hydrogen peroxide treatment. Overexpression of MsrA gene products in ES cells showed improved survivability of these cells to hydrogen peroxide treatment. Our results indicate that MsrA plays an important role in cellular defenses against oxidative stress in ESCs. Msr genes may provide a new target in stem cells to increase their survivability during the therapeutic applications. J. Cell. Biochem. 111: 94–103, 2010. © 2010 Wiley‐Liss, Inc.
Expression profile of the embryonic markers nanog, OCT‐4, SSEA‐1, SSEA‐4, and frizzled‐9 receptor in human periodontal ligament mesenchymal stem cells
Authors: Trubiani Oriana , Zalzal Sylvia Francis , Paganelli Roberto , Marchisio Marco , Giancola Raffaella , Pizzicannella Jacopo , Bühring Hans‐Jörg , Piattelli Maurizio , Caputi Sergio , Nanci Antonio
Published: April 2010

Mesenchymal stem cells (MSCs) are self‐renewing cells with the ability to differentiate into various mesodermal‐derived tissues. Recently, we have identified in adult human periodontal ligament (PDL) a population of stem cells (PDL‐MSCs) with the ability to differentiate into osteoblasts and adipocytes. The aim of the present work was to further characterize this population and the expression profile of its cells. To achieve our objective we have used flow cytometry, magnetic cell sorting, cytokine antibody array, and light and electron microscope immunostaining. Our results show that the PDL‐MSCs contain a subpopulation of frizzled‐9 (CD349) positive cells expressing a panel of key mesenchymal and embryonic markers including CD10, CD26, CD29, CD44, CD73, CD90, CD105, CD166, SSEA‐1, and SSEA‐4. They are additionally positive for nanog and Oct‐4; two critical transcription factors directing self‐renewal and pluripotency of embryonic stem cells, and they also express the cytokines EGF and IP‐10. The presence of nanog, Oct‐4, SSEA‐1, and SSEA‐4 suggests that PDL‐MSCs are less differentiated than bone marrow‐derived MSCs. Taken together, these data indicate the presence of immature MSCs in PDL and suggest that the frizzled‐9/Wnt pathway plays an important role in regulating proliferation and differentiation of these cells. J. Cell. Physiol. 225: 123–131, 2010. © 2010 Wiley‐Liss, Inc.
Potential localization of putative stem/progenitor cells in human bulbar conjunctival epithelium
Authors: Qi Hong , Zheng Xiaofen , Yuan Xiaoyong , Pflugfelder Stephen C. , Li De‐Quan
Published: April 2010

Although the conjunctival fornix appears to contain the greatest proportion of stem cells, it is likely that pockets of conjunctival epithelial stem cells may also exist throughout the conjunctival epithelium. This study was to investigate the potential localization of putative stem/progenitor cells in the human bulbar conjunctival epithelium by evaluating 6 keratins and 13 molecules that have been previously proposed stem cell associated or differentiation markers. We found that cornea specific cytokeratin (CK) 3 was not expressed by the bulbar conjunctival epithelial cells. In contrast, CK4 and CK7 were expressed by the superficial cells of bulbar conjunctival epithelium. CK14 and CK15 were confined to the basal cell layer. CK19 was strongly expressed by all layers of the bulbar conjunctival epithelium. The expression patterns of molecular markers in the basal cells of human bulbar conjunctival epithelium were found to be similar to the corneal epithelium. Basal conjunctival epithelial cells strongly expressed stem cell associated markers, including ABCG2, p63, nerve growth factor (NGF) with its receptors tyrosine kinase receptor A (TrkA) and neurotrophin low‐affinity receptor p75NTR, glial cell‐derived neurotrophic factor (GDNF) with its receptor GDNF family receptor alpha 1 (GFRα‐1), integrin β1, α‐enolase, and epidermal growth factor receptor (EGFR). The differentiation associated markers nestin, E‐cadherin and involucrin were not expressed by these cells. These findings indicate that the basal cells of bulbar conjunctival epithelium shares a similar expression pattern of stem cell associated markers to the corneal epithelium, but has a unique pattern of differentiation associated cytokeratin expression. J. Cell. Physiol. 225: 180–185, 2010. © 2010 Wiley‐Liss, Inc.
Quantitative multiparametric PROPELLER MRI of diethylnitrosamine‐induced hepatocarcinogenesis in wister rat model
Authors: Deng Jie , Jin Ning , Yin Xiaoming , Yang Guang‐Yu , Zhang Zhuoli , Omary Reed A. , Larson Andrew C.
Published: April 2010

Purpose:

To develop a quantitative multiparametric PROPELLER (periodically rotated overlapping parallel lines with enhanced reconstruction) magnetic resonance imaging (MRI) approach and its application in a diethylnitrosamine (DEN) chemically induced rodent model of hepatocarcinogenesis for lesion characterization.

Materials and Methods:

In nine rats with 33 cirrhosis‐associated hepatic nodules including regenerative nodule (RN), dysplastic nodule (DN), hepatocellular carcinoma (HCC), and cyst, multiparametric PROPELLER MRI (diffusion‐weighted, T2/M0 (proton density) mapping and T1‐weighted) were performed. Apparent diffusion coefficient (ADC) maps, T2 and M0 maps of each tumor were generated. We compared ADC, T2, and M0 measurements for each type of hepatic nodule, confirmed at histopathology.

Results:

PROPELLER images and resultant parametric maps were inherently coregistered without image distortion or motion artifacts. All types of hepatic nodules demonstrated complex imaging characteristics within conventional T1‐ and T2‐weighted images. Quantitatively, cysts were distinguished from RN, DN, and HCC with significantly higher ADC and T2; however, there was no significant difference of ADC and T2 between HCC, DN, and RN. Mean tumor M0 values of HCC were significantly higher than those of DN, RN, and cysts.

Conclusion:

This study exploited quantitative PROPELLER MRI and multidimensional analysis approaches in an attempt to differentiate hepatic nodules in the DEN rodent model of hepatocarcinogenesis. This method offers great potential for parallel parameterization during noninvasive interrogation of hepatic tissue properties. J. Magn. Reson. Imaging 2010;31:1242–1251. © 2010 Wiley‐Liss, Inc.
Magnetic resonance imaging in the evaluation of (deep infiltrating) endometriosis: The value of diffusion‐weighted imaging
Authors: Busard M.P.H. , Mijatovic V. , van Kuijk C. , Pieters‐van den Bos I.C. , Hompes P.G.A. , van Waesberghe J.H.T.M.
Published: April 2010

Purpose

To assess the value of magnetic resonance (MR) diffusion‐weighted imaging (DWI) in the evaluation of deep infiltrating endometriosis (DIE).

Materials and Methods

In a prospective single‐center study, DWI was added to the standard MRI protocol in 56 consecutive patients with known or suspected endometriosis. Endometriotic lesions as well as (functional) ovarian cysts were analyzed for location, size, and signal intensity on T1, T2, and DWI. Apparent diffusion coefficient (ADC) values were calculated using b‐values of 50, 400, 800, and 1200 s/mm2. Statistical analysis included the Spearman correlation coefficient, Mann–Whitney U, and Kruskal–Wallis tests.

Results

A total of 112 lesions (62 endometrial cysts and 48 DIE) were detected, 60 of which were large enough to analyze. Mean ADC values of endometrial cysts and functional ovarian cysts were 1.11 × 10−3/mm2/s and 2.14 × 10−3/mm2/s, respectively. Mean ADC values of DIE retrocervical, infiltrating the colon, and bladder were 0.70 × 10−3/mm2/s, 0.79 × 10−3/mm2/s, and 0.76 × 10−3/mm2/s, respectively. ADC values of DIE did not show a significant difference between varying pelvic locations (P = 0.63).

Conclusion

Results of our study suggest that ADC values of DIE are consistently low, without significant difference between pelvic locations. J. Magn. Reson. Imaging 2010;31:1117–1123. © 2010 Wiley‐Liss, Inc.
Visual pathway lesion and its development during hyperbaric oxygen treatment: A bold‐ fMRI and DTI study
Authors: Chen Ziqian , Ni Ping , Lin Yuning , Xiao Hui , Chen Jinhua , Qian Gennian , Ye Youqiang , Xu Shangwen , Wang Jinliang , Yang Xizhang
Published: April 2010

Purpose

To characterize and evaluate functional and anatomic changes of visual pathway lesions during hyperbaric oxygen (HBO) treatment with blood‐oxygenation‐level‐dependent functional MRI (BOLD‐fMRI) and diffusion tensor imaging (DTI).

Materials and Methods

Sixteen patients with visual pathway lesions received HBO treatment. Both BOLD‐fMRI and DTI were performed before and after the treatment, while 12 healthy subjects were also studied with 2 examinations as control. The t‐tests were used for the comparison of number of activated voxels (AVs) and fractional anisotropy (FA) between the two groups, and within the patient group before and after HBO treatment. Visual acuity of the patient group before and after the treatment was compared using Wilcoxon signed‐rank test.

Results

Before the treatment, both AVs (P < 0.01) and FA (P < 0.05) in the bilateral cortexes of occipital lobes were significantly less in the patient group than in the control group. After the treatment, both AVs (P < 0.05) and FA (P < 0.05) were significantly increased. Moreover, The FA of 6 patients with lesions in the optical nerve was greater than the FA of the other 10 patients with lesions in the optic radiation (P < 0.05).

Conclusion

BOLD‐fMRI combined with DTI was useful for the characterization and evaluation of anatomic and functional changes of visual pathway lesions and their development during HBO treatment. J. Magn. Reson. Imaging 2010;31:1054–1060. © 2010 Wiley‐Liss, Inc.
Fat suppression with short inversion time inversion‐recovery and chemical‐shift selective saturation: A dual STIR‐CHESS combination prepulse for turbo spin echo pulse sequences
Authors: Tanabe Koji , Nishikawa Keiichi , Sano Tsukasa , Sakai Osamu , Jara Hernán
Published: April 2010

Purpose:

To test a newly developed fat suppression magnetic resonance imaging (MRI) prepulse that synergistically uses the principles of fat suppression via inversion recovery (STIR) and spectral fat saturation (CHESS), relative to pure CHESS and STIR. This new technique is termed dual fat suppression (Dual‐FS).

Materials and Methods:

To determine if Dual‐FS could be chemically specific for fat, the phantom consisted of the fat‐mimicking NiCl2 aqueous solution, porcine fat, porcine muscle, and water was imaged with the three fat‐suppression techniques. For Dual‐FS and STIR, several inversion times were used. Signal intensities of each image obtained with each technique were compared. To determine if Dual‐FS could be robust to magnetic field inhomogeneities, the phantom consisting of different NiCl2 aqueous solutions, porcine fat, porcine muscle, and water was imaged with Dual‐FS and CHESS at the several off‐resonance frequencies. To compare fat suppression efficiency in vivo, 10 volunteer subjects were also imaged with the three fat‐suppression techniques.

Results:

Dual‐FS could suppress fat sufficiently within the inversion time of 110–140 msec, thus enabling differentiation between fat and fat‐mimicking aqueous structures. Dual‐FS was as robust to magnetic field inhomogeneities as STIR and less vulnerable than CHESS. The same results for fat suppression were obtained in volunteers.

Conclusion:

The Dual‐FS‐STIR‐CHESS is an alternative and promising fat suppression technique for turbo spin echo MRI. J. Magn. Reson. Imaging 2010;31:1277–1281. ©2010 Wiley‐Liss, Inc.
Enhanced image quality in black‐blood MRI using the improved motion‐sensitized driven‐equilibrium (iMSDE) sequence
Authors: Wang Jinnan , Yarnykh Vasily L. , Yuan Chun
Published: April 2010

Purpose

To propose an improved motion‐sensitized driven‐equilibrium (iMSDE) pulse sequence to enhance the tissue signal‐to‐noise ratio (SNR) while maintaining the same flow suppression capability in black‐blood carotid artery magnetic resonance imaging (MRI).

Materials and Methods

Compared to the traditional MSDE sequence, the iMSDE sequence uses an extra refocusing pulse and two extra gradients to achieve SNR improvement. Computer simulation and phantom studies were used to evaluate both eddy currents and local B1 inhomogeneity effects on SNR behaviors on both MSDE and iMSDE images. To further assess the SNR improvements brought by iMSDE in vivo, five healthy volunteers were also scanned with both sequences. The paired t‐test was used for statistical comparison.

Results

Both simulations and phantom studies demonstrated that eddy currents and local B1 inhomogeneity will cause image SNR reduction in the MSDE sequence, and that these factors can be partially compensated for with the iMSDE sequence. In vivo comparison showed that the iMSDE sequence significantly improved the tissue‐lumen contrast‐to‐noise ratio (CNR) and static tissue SNR (P < 0.001 for both), while maintaining low lumen SNR in carotid MRI.

Conclusion

Compared to the traditional MSDE sequence, the iMSDE sequence can achieve improved soft‐tissue SNR and CNR in carotid artery MRI without sacrificing flow suppression capability and time efficiency. J. Magn. Reson. Imaging 2010;31:1256–1263. © 2010 Wiley‐Liss, Inc.
Quantitative diffusion weighted imaging for differentiation of benign and malignant breast lesions: The influence of the choice of b‐values
Authors: Peters Nicky H.G.M. , Vincken Koen L. , van den Bosch Maurice A.A.J. , Luijten Peter R. , Mali Willem P.Th.M. , Bartels Lambertus W.
Published: April 2010

Purpose:

To evaluate the influence of the choice of different combinations of b‐values on the ADC and on the diagnostic performance of quantitative diffusion weighted imaging (DWI) in breast lesions.

Materials and Methods:

Seventy‐three patients (90 lesions) underwent 3 Tesla (T) breast MRI including a DWI‐scan using b‐values 0, 150, 499, and 1500 s/mm2 and histological analysis. Five combinations of b‐values were used to calculate the ADC, each with different sensitivities to perfusion and diffusion effects. The median ADC of benign lesions, noninvasive carcinomas and invasive carcinomas and the diagnostic performance of the five methods were compared.

Results:

Eighty‐eight lesions were analyzed (37 benign, 13 noninvasive carcinomas, 38 invasive carcinomas). The median ADC was highest in benign lesions, intermediate in noninvasive carcinomas and lowest in invasive carcinomas for all methods. Calculating the ADC with the lowest 2 b‐values yielded the highest ADC for all lesions types; the highest 2 b‐values yielded the lowest ADC. The area under the receiver operating characteristic curve was approximately equal for all methods.

Conclusion:

The ADC of breast lesions varied substantially with the choice of different b‐values, indicating that absolute ADC threshold values to differentiate benign and malignant lesions should be interpreted with caution. However, the diagnostic performance of quantitative DWI was not affected by the choice of different b‐values. J. Magn. Reson. Imaging 2010;31:1100–1105. © 2010 Wiley‐Liss, Inc.
Identification of brown adipose tissue in mice with fat–water IDEAL‐MRI
Authors: Hu Houchun H. , Smith Daniel L. , Nayak Krishna S. , Goran Michael I. , Nagy Tim R.
Published: April 2010

Purpose:

To investigate the feasibility of using IDEAL (Iterative Decomposition with Echo Asymmetry and Least squares estimation) fat–water imaging and the resultant fat fraction metric in detecting brown adipose tissue (BAT) in mice, and in differentiating BAT from white adipose tissue (WAT).

Materials and Methods:

Excised WAT and BAT samples and whole‐mice carcasses were imaged with a rapid three‐dimensional fat–water IDEAL‐SPGR sequence on a 3 Tesla scanner using a single‐channel wrist coil. An isotropic voxel size of 0.6 mm was used. Excised samples were also scanned with single‐voxel proton spectroscopy. Fat fraction images from IDEAL were reconstructed online using research software, and regions of WAT and BAT were quantified.

Results:

A broad fat fraction range for BAT was observed (40–80%), in comparison to a tighter and higher WAT range of 90–93%, in both excised tissue samples and in situ. Using the fat fraction metric, the interscapular BAT depot in each carcass could be clearly identified, as well as peri‐renal and inguinal depots that exhibited a mixed BAT and WAT phenotype appearance.

Conclusion:

Due to BAT's multi‐locular fat distribution and extensive mitochondrial, cytoplasm, and vascular supply, its fat content is significantly less than that of WAT. We have demonstrated that the fat fraction metric from IDEAL‐MRI is a sensitive and quantitative approach to noninvasively characterize BAT. J. Magn. Reson. Imaging 2010;31:1195–1202. © 2010 Wiley‐Liss, Inc.
In vitro assessment of flow patterns and turbulence intensity in prosthetic heart valves using generalized phase‐contrast MRI
Authors: Kvitting John‐Peder Escobar , Dyverfeldt Petter , Sigfridsson Andreas , Franzén Stefan , Wigström Lars , Bolger Ann F. , Ebbers Tino
Published: April 2010

Purpose:

To assess in vitro the three‐dimensional mean velocity field and the extent and degree of turbulence intensity (TI) in different prosthetic heart valves using a generalization of phase‐contrast MRI (PC‐MRI).

Materials and Methods:

Four 27‐mm aortic valves (Björk‐Shiley Monostrut tilting‐disc, St. Jude Medical Standard bileaflet, Medtronic Mosaic stented and Freestyle stentless porcine valve) were tested under steady inflow conditions in a Plexiglas phantom. Three‐dimensional PC‐MRI data were acquired to measure the mean velocity field and the turbulent kinetic energy (TKE), a direction‐independent measure of TI.

Results:

Velocity and TI estimates could be obtained up‐ and downstream of the valves, except where metallic structure in the valves caused signal void. Distinct differences in the location, extent, and peak values of velocity and TI were observed between the valves tested. The maximum values of TKE varied between the different valves: tilting disc, 100 J/m3; bileaflet, 115 J/m3; stented, 200 J/m3; stentless, 145 J/m3.

Conclusion:

The TI downstream from a prosthetic heart valve is dependent on the specific valve design. Generalized PC‐MRI can be used to quantify velocity and TI downstream from prosthetic heart valves, which may allow assessment of these aspects of prosthetic valvular function in postoperative patients. J. Magn. Reson. Imaging 2010;31:1075–1080. © 2010 Wiley‐Liss, Inc.
Modified brix model analysis of bone perfusion in subjects of varying bone mineral density
Authors: Ma Heather Ting , Griffith James F. , Yeung David K. , Leung P.C.
Published: April 2010

Purpose:

To apply pharmacokinetic modeling to the investigation of bone perfusion in subjects of varying bone mineral density.

Materials and Methods:

This study re‐analyzed previous experimental data. A modified pharmacokinetic model was applied to data obtained from two prior studies of dynamic contrast‐enhanced MR imaging of L3 vertebral body in 165 subjects (65 males, 100 females), classified into three groups (normal, osteopenia, and osteoporosis) according to bone mineral density. Three parameters, amplitude A, exchange rate (kep), and elimination rate (kel), were obtained by fitting the signal intensity to the pharmacokinetic model. These parameters were compared across the three groups for males and females, respectively.

Results:

Perfusion parameters, amplitude A was found to be reduced in osteoporotic subjects with additional, though less pronounced, reductions found in the permeability constant (A*kep) and the elimination rate (kel). Increased marrow fat content was found in osteoporotic bone, which helped to partially explain the observed reduction in interstitial space.

Conclusion:

By pharmacokinetic model, bone perfusion can be quantitatively analyzed with alteration in functional parameters related to microcirculation in subjects of varying bone mineral density. Developing bone marrow specific pharmacokinetic models should help to deepen knowledge of physiological and pathological perfusion changes occurring in bone. J. Magn. Reson. Imaging 2010;31:1169–1175. © 2010 Wiley‐Liss, Inc.
Ruthenium(III)‐mediated oxidation of D‐mannitol by cerium(IV) in aqueous sulfuric acid medium: A kinetic and mechanistic approach
Authors: Hosahalli Rajeshwari V. , Savanur Anita P. , Nandibewoor Sharanappa T. , Chimatadar Shivamurti A.
Published: April 2010

The oxidation of D‐mannitol by cerium(IV) has been studied spectrophotometrically in aqueous sulfuric acid medium at 25°C at constant ionic strength of 1.60 mol dm−3. A microamount of ruthenium(III) (10−6 mol dm−3) is sufficient to enhance the slow reaction between D‐mannitol and cerium(IV). The oxidation products were identified by spot test, IR and GC‐MS spectra. The stoichiometry is 1:4, i.e., [D‐mannitol]: [Ce(IV)] = 1:4. The reaction is first order in both cerium(IV) and ruthenium(III) concentrations. The order with respect to D‐mannitol concentration varies from first order to zero order as the D‐mannitol concentration increases. Increase in the sulfuric acid concentration decreases the reaction rate. The added sulfate and bisulfate decreases the rate of reaction. The active species of oxidant and catalyst are Ce(SO4)2 and [Ru(H2O)6]3+, respectively. A possible mechanism is proposed. The activation parameters are determined with respect to a slow step and reaction constants involved have been determined. © 2010 Wiley Periodicals, Inc. Int J Chem Kinet 42: 440–452, 2010
In vivo near‐IR imaging of approximal dental decay at 1,310 nm
Authors: Staninec Michal , Lee Chulsung , Darling Cynthia L. , Fried Daniel
Published: April 2010

Objective

The high transparency of dental enamel in the near‐IR (NIR) light at 1,310‐nm can be exploited for imaging dental caries without the use of ionizing radiation (X‐rays). We present the results of the first in vivo imaging study in which NIR images were acquired of approximal contact surfaces.

Methods

NIR imaging hand‐pieces were developed and attached to a compact InGaAs focal plane array and subsequently used to acquire in vivo NIR images of 33 caries lesions on 18 test subjects. The carious lesions were discernible on bitewing radiographs, but were not visible upon clinical examination.

Results

NIR images were acquired in vivo from three directions and the majority of lesions examined were too small to require restoration, based on accepted bitewing radiograph criteria. All but one of the 33 lesions examined were successfully imaged from at least one direction.

Conclusion

This first in vivo study of imaging at the 1,310‐nm wavelength region shows that NIR imaging has great potential as a screening tool for the detection of approximal lesions without the use of ionizing radiation. Lasers Surg. Med. 42:292–298, 2010. © 2010 Wiley‐Liss, Inc.
Blood flow assessment with magnetic resonance imaging after 1.9 µm diode laser‐assisted microvascular anastomosis
Authors: Leclère Franck Marie P. , Schoofs Michel , Auger Florent , Buys Bruno , Mordon Serge R.
Published: April 2010

Background and Objectives

Microvascular surgery associates intricate surgical techniques to join tiny blood vessels and help transfer large amount of tissues. Successful venous anastomosis remains the main challenge because inadequate blood flow correlates with a major risk of free flaps venous congestion and thrombosis. The aim of this study is to assess blood flow after laser‐assisted microvascular anastomosis (LAMA) using a 1.9‐µm diode laser.

Study Design/Materials and Methods

LAMA was performed on a series of 10 external jugular veins of Wistar rats. Two stay sutures and a standard laser tissue welding technique (λ: 1.9 µm; power: 110 mW) were used. Similarly, a series of 10 conventional venous anastomosis were performed (CSMA). In both groups, contralateral non‐operated jugular veins were used as control. MRI was used to perform positioning, anatomical, angiographic blood flow sequences, 1 day post‐procedure and at 1, 4 and 8 weeks.

Results

Venous patency rate was 100% at the time of surgery. Mean clamping time was 7.9 minutes in the LAMA group compared to 11.4 minutes in the CSMA group. In the angiographic sequence, there were no aneurysms in both groups for all observation periods. At post‐operative day 1, mean loss of blood flow at the level of anastomosis in the LAMA group was 7% compared with 22% in the CSMA group. At 1, 4 and 8 weeks, blood flow reduction was greater in the CSMA group: 34%, 38% and 41%, respectively, compared to 12%, 15% and 16% in the LAMA group. Moreover, three cases of thrombosis were observed in the venous anastomosis performed with the conventional technique at 1 (n = 2) and 3 months (n = 1).

Conclusion

The flow‐MRI further demonstrates that 1.9 µm diode LAMA is a consistent, reliable and reproducible technique, capable of improving blood flow in veins when compared to conventional surgery. Lasers Surg. Med. 42:299–305, 2010. © 2010 Wiley‐Liss, Inc.
Improving TV weather broadcasts with technological advancements: two cases from a 20 year perspective
Authors: Bech Joan , Molina Tomàs , Vilaclara Eliseu , Lorente Jeroni
Published: April 2010

The introduction of technological advancements in TV weather broadcasts has been a constant trend, particularly in the last 20 years. Rapidly evolving techniques, both from the point of view of new meteorological products or the use of advanced computer generated graphics, have offered a wide choice of possibilities to enhance information content and communication capability. However, despite the potential advantage of technological innovation, a case‐by‐case careful feasibility analysis is always required, including not only technical and economical aspects, but most importantly communication issues bearing in mind the education and acceptance of the audience.

In this paper two specific cases of technological advances in TV weather broadcasts, seen from the perspective of the last 20 years, are examined: the introduction of weather radar images and the use of animated characters as weathercasters. These cases are illustrated from the experience acquired in TVC, the public Television of Catalonia (NE Spain). Direct access to weather radar data was first made possible within the framework of a joint collaboration agreement with the University of Barcelona and the Meteorological Service of Catalonia, which installed a new C‐band Doppler radar. The use of animated characters as weathercasters was the result of developing and advanced human‐like interface accessing an already existing database fed automatically by NWP forecasts. In each case a description of both technical aspects and also of the benefits and challenges seen from the communication point of view found in their introduction in TV weather broadcasts is provided. Copyright © 2010 Royal Meteorological Society
Public perception of and response to severe weather warnings in Nova Scotia, Canada
Authors: Silver Amber , Conrad Catherine
Published: April 2010

Hurricane Juan, which struck Atlantic Canada on 29 September, 2003, revealed the full extent of public vulnerability to severe weather events in Nova Scotia. In this study, 130 people were interviewed via a systematic sampling technique to examine their perception of severe weather warnings, and to determine what actions (if any) they are most likely to take when a warning has been posted. It was found that different target groups (e.g. the elderly, students) use different modes of media to obtain their severe weather information. It is recommended that forecast centres tailor their advisories for specific media sources so as best to reach various target groups. It was also found that respondents are generally satisfied with the weather warnings they receive, but there is a lack of awareness of the existence and extent of public vulnerability in Nova Scotia. The development of a comprehensive education campaign which will outline various facets of social vulnerability, while also offering recommendations on how best to lower existing social vulnerability, is critical. Copyright © 2010 Royal Meteorological Society
3D magnetization‐prepared imaging using a stack‐of‐rings trajectory
Authors: Wu Holden H. , Nishimura Dwight G.
Published: April 2010

Efficient acquisition strategies for magnetization‐prepared imaging based on the three‐dimensional (3D) stack‐of‐rings k‐space trajectory are presented in this work. The 3D stack‐of‐rings can be acquired with centric ordering in all three dimensions for greater efficiency in capturing the desired contrast. In addition, the 3D stack‐of‐rings naturally supports spherical coverage in k‐space for shorter scan times while achieving isotropic spatial resolution. While non‐Cartesian trajectories generally suffer from greater sensitivity to system imperfections, the 3D stack‐of‐rings can enhance magnetization‐prepared imaging with a high degree of robustness to timing delays and off‐resonance effects. As demonstrated with phantom scans, timing errors and gradient delays only cause a bulk rotation of the 3D stack‐of‐rings reconstruction. Furthermore, each ring can be acquired with a time‐efficient retracing design to resolve field inhomogeneities and enable fat/water separation. To demonstrate its effectiveness, the 3D stack‐of‐rings are considered for the case of inversion‐recovery‐prepared structural brain imaging. Experimental results show that the 3D stack‐of‐rings can achieve higher signal‐to‐noise ratio and higher contrast‐to‐noise ratio within a shorter scan time when compared to the standard inversion‐recovery‐prepared sequence based on 3D Cartesian encoding. The design principles used for this specific case of inversion‐recovery‐prepared brain imaging can be applied to other magnetization‐prepared imaging applications. Magn Reson Med 63:1210–1218, 2010. © 2010 Wiley‐Liss, Inc.
Concatenated and parallel optimization for the estimation of T1 map in FLASH MRI with multiple flip angles
Authors: Wang Defeng , Shi Lin , Wang Yi‐Xiang J. , Yuan Jing , Yeung David K.W. , King Ann D. , Ahuja Anil T. , Heng Pheng Ann
Published: April 2010

Most traditional methods for T1 map estimation in MRI with fast low‐angle‐shot sequences are aimed at high efficiency by compromising the fitting accuracy. In this paper, the fundamental problem of parameter estimation in fast low‐angle‐shot MRI was re‐examined, and an accurate and fast optimization approach, named concatenated optimization for parameter estimation, was proposed for the regression of data points acquired with multiple flip angles. The initial estimation of T1 was obtained from the linear regression, followed by the constrained nonlinear regression based on the initial estimates. This heterogeneous initialization strategy improves the fitting accuracy and reduces the computational time. A computationally efficient implementation of concatenated optimization for parameter estimation was achieved based on the graphic processing unit, named as concatenated optimization for parameter estimation graphic processing unit. In experimental comparison with Fram's method and the Fitter Tool in Jim, the proposed methods are capable of achieving significantly higher efficiency and more accurate estimations. Magn Reson Med 63:1431–1436, 2010. © 2010 Wiley‐Liss, Inc.
Optimum SNR data compression in hardware using an Eigencoil array
Authors: King Scott B. , Varosi Steve M. , Duensing G. Randy
Published: April 2010

With the number of receivers available on clinical MRI systems now ranging from 8 to 32 channels, data compression methods are being explored to lessen the demands on the computer for data handling and processing. Although software‐based methods of compression after reception lessen computational requirements, a hardware‐based method before the receiver also reduces the number of receive channels required. An eight‐channel Eigencoil array is constructed by placing a hardware radiofrequency signal combiner inline after preamplification, before the receiver system. The Eigencoil array produces signal‐to‐noise ratio (SNR) of an optimal reconstruction using a standard sum‐of‐squares reconstruction, with peripheral SNR gains of 30% over the standard array. The concept of “receiver channel reduction” or MRI data compression is demonstrated, with optimal SNR using only four channels, and with a three‐channel Eigencoil, superior sum‐of‐squares SNR was achieved over the standard eight‐channel array. A three‐channel Eigencoil portion of a product neurovascular array confirms in vivo SNR performance and demonstrates parallel MRI up toR= 3. This SNR‐preserving data compression method advantageously allows users of MRI systems with fewer receiver channels to achieve the SNR of higher‐channel MRI systems. Magn Reson Med 63:1346–1356, 2010. © 2010 Wiley‐Liss, Inc.
Phase‐field dithering for active catheter tracking
Authors: Dumoulin Charles L. , Mallozzi Richard P. , Darrow Robert D. , Schmidt Ehud J.
Published: April 2010

A strategy to increase the robustness of active MR tracking of microcoils in low signal‐to‐noise ratio conditions was developed and tested. The method employs dephasing magnetic field gradient pulses that are applied orthogonal to the frequency‐encoding gradient pulse used in conventional point‐source MR tracking. In subsequent acquisitions, the orthogonal dephasing gradient pulse is rotated while maintaining a perpendicular orientation with respect to the frequency‐encoding gradient. The effect of the dephasing gradient is to apply a spatially dependent phase shift in directions perpendicular to the frequency‐encoding gradient. Since the desired MR signal for robust MR tracking comes from the small volume of nuclear spins near the small detection coil, the desired signal is not dramatically altered by the dephasing gradient. Undesired MR signals arising from larger volumes (e.g., due to coupling with the body coil or surface coils), on the other hand, are dephased and reduced in signal intensity. Since the approach requires no a priori knowledge of the microcoil orientation with respect to the main magnetic field, data from several orthogonal dephasing gradients are acquired and analyzed in real time. One of several selection algorithms is employed to identify the “best” data for use in the coil localization algorithm. This approach was tested in flow phantoms and animal models, with several multiplexing schemes, including the Hadamard and zero‐phase reference approaches. It was found to provide improved MR tracking of untuned microcoils. It also dramatically improved MR tracking robustness in low signal‐to‐noise‐ratio conditions and permitted tracking of microcoils that were inductively coupled to the body coil. Magn Reson Med 63:1398–1403, 2010. © 2010 Wiley‐Liss, Inc.
Separation of macrovascular signal in multi‐inversion time arterial spin labelling MRI
Authors: Chappell Michael A. , MacIntosh Bradley J. , Donahue Manus J. , Günther Matthias , Jezzard Peter , Woolrich Mark W.
Published: April 2010

Arterial spin labeling (ASL) provides a noninvasive method to measure brain perfusion and is becoming an increasingly viable alternative to more invasive MR methods due to improvements in acquisition, such as the use of a three‐dimensional GRASE readout. A potential source of error in ASL measurements is signal arising from intravascular blood that is destined for more distal tissue. This is typically suppressed using diffusion gradients in many ASL sequences. However, several problems exist with this approach, such as the choice of cutoff velocity and gradient direction and incompatibility with certain readout modules. An alternative approach is to explicitly model the intravascular signal. This study exploits this approach by using multi‐inversion time ASL data with a recently developed model‐fitting method. The method employed permits the intravascular contribution to be discarded in voxels where there is no support in the data for its inclusion, thereby addressing the issue of overfitting. It is shown by comparing data with and without flow suppression, and by comparing the intravascular contribution in GRASE ASL data to MR angiographic images, that the model‐fitting approach can provide a viable alternative to flow suppression in ASL where suppression is either not feasible or not desirable. Magn Reson Med 63:1357–1365, 2010. © 2010 Wiley‐Liss, Inc.
Optimal design of multiple‐channel RF pulses under strict power and SAR constraints
Authors: Brunner David O. , Pruessmann Klaas P.
Published: April 2010

Parallel radio frequency transmission has recently been explored as a means of tailoring the spatial response of MR excitation. In particular, parallel transmission is increasingly used to accelerate radio frequency pulses that rely on time‐varying gradient fields to achieve selectivity in multiple dimensions. The design of the underlying multiple‐channel radio frequency waveforms is mostly based on regularized least‐squares optimization in close analogy with image reconstruction in parallel imaging. However, this analogy has important limitations. Unlike image reconstruction, the design of radio frequency waveforms is subject to multiple strict constraints, which arise from technical power limits, as well as safety limits on local and global energy deposition in vivo. To optimize excitation profiles under such strict constraints, it is proposed to depart from the regularization strategy and rely on semidefinite programming instead. To render this approach fast, it is performed in a reduced search space, which is obtained by initial Lanczos iteration. The proposed algorithm is demonstrated to enable efficient pulse optimization within exactly the given constraints, including local specific absorption rate limits for multiple compartments. It is also shown that the proposed approach readily accommodates advanced forward models of the excitation process, including the effects of local off‐resonance and transverse relaxation. Magn Reson Med 63:1280–1291, 2010. © 2010 Wiley‐Liss, Inc.
Susceptibility mapping in the human brain using threshold‐based k‐space division
Authors: Wharton Sam , Schäfer Andreas , Bowtell Richard
Published: April 2010

A method for calculating quantitative three‐dimensional susceptibility maps from field measurements acquired using gradient echo imaging at high field is presented. This method is based on division of the three‐dimensional Fourier transforms of high‐pass‐filtered field maps by a simple function that is the Fourier transform of the convolution kernel linking field and susceptibility, and uses k‐space masking to avoid noise enhancement in regions where this function is small. Simulations were used to show that the method can be applied to data acquired from objects that are oriented at one angle or multiple angles with respect to the applied field and that the use of multiple orientations improves the quality of the calculated susceptibility maps. As part of this work, we developed an improved approach for high‐pass filtering of field maps, based on using an arrangement of dipoles to model the fields generated by external structures. This approach was tested on simulated field maps from the substantia nigra and red nuclei. Susceptibility mapping was successfully applied to experimental measurements on a structured phantom and then used to make measurements of the susceptibility of the red nuclei and substantia nigra in healthy subjects at 3 and 7 T. Magn Reson Med 63:1292–1304, 2010. © 2010 Wiley‐Liss, Inc.
Dynamic susceptibility contrast MRI with localized arterial input functions
Authors: Lee John J. , Bretthorst G. Larry , Derdeyn Colin P. , Powers William J. , Videen Tom O. , Snyder Abraham Z. , Markham Joanne , Shimony Joshua S.
Published: April 2010

Compared to gold‐standard measurements of cerebral perfusion with positron emission tomography using H2[15O] tracers, measurements with dynamic susceptibility contrast MR are more accessible, less expensive, and less invasive. However, existing methods for analyzing and interpreting data from dynamic susceptibility contrast MR have characteristic disadvantages that include sensitivity to incorrectly modeled delay and dispersion in a single, global arterial input function. We describe a model of tissue microcirculation derived from tracer kinetics that estimates for each voxel a unique, localized arterial input function. Parameters of the model were estimated using Bayesian probability theory and Markov‐chain Monte Carlo, circumventing difficulties arising from numerical deconvolution. Applying the new method to imaging studies from a cohort of 14 patients with chronic, atherosclerotic, occlusive disease showed strong correlations between perfusion measured by dynamic susceptibility contrast MR with localized arterial input function and perfusion measured by quantitative positron emission tomography with H2[15O]. Regression to positron emission tomography measurements enabled conversion of dynamic susceptibility contrast MR to a physiologic scale. Regression analysis for localized arterial input function gave estimates of a scaling factor for quantitation that described perfusion accurately in patients with substantial variability in hemodynamic impairment. Magn Reson Med 63:1305–1314, 2010. © 2010 Wiley‐Liss, Inc.
Field‐cycling NMR relaxometry with spatial selection
Authors: Pine Kerrin J. , Davies Gareth R. , Lurie David J.
Published: April 2010

Fast field‐cycling MRI offers access to sources of endogenous information not available from conventional fixed‐field imagers. One example is the T1 dispersion curve: a plot of T1 versus field strength. We present a pulse sequence that combines saturation‐recovery/inversion‐recovery T1 determination with field cycling and point‐resolved spectroscopy localization, enabling the measurement of dispersion curves from volumes selected from a pilot image. Compared with a nonselective sequence, our method of volume selection does not influence measurement accuracy, even for relatively long echo times and in the presence of radiofrequency field nonuniformity. The measured voxel profile, while not ideal, corresponds with that expected from the image slice profile. On a whole‐body fast field‐cycling scanner with 59‐mT detection, the sensitivity of the experiment is sufficient to reveal distinctive “quadrupole dips” in dispersion curves of protein‐rich human tissue in vivo. Magn Reson Med, 2010. © 2010 Wiley‐Liss, Inc.
In vivo 3.0‐tesla magnetic resonance T1ρ and T2 relaxation mapping in subjects with intervertebral disc degeneration and clinical symptoms
Authors: Blumenkrantz Gabrielle , Zuo Jin , Li Xiaojuan , Kornak John , Link Thomas M. , Majumdar Sharmila
Published: April 2010

The purpose of this study is (1) to determine the correlation between T1ρ and T2 and degenerative grade in intervertebral discs using in vivo 3.0‐T MRI, and (2) to determine the association between T1ρ and T2 and clinical findings as quantified by the SF‐36 Questionnaire and Oswestry Disability Index. Sixteen subjects participated in this study, and each completed SF‐36 and Oswestry Disability Index questionnaires. MRI T1ρ and T2 mapping was performed to determine T1ρ (77 discs) and T2 (44 discs) in the nucleus of the intervertebral disc, and T2‐weighted images were acquired for Pfirrmann grading of disc degeneration. Pfirrmann grade was correlated with both T1ρ (r = −0.84; P < 0.01) and T2 (r = −0.61; P < 0.01). Mixed‐effects models demonstrate that only T1ρ was associated with clinical questionnaires (R2SF‐36 = 0.55, R2O.D.I. = 0.56; P < 0.05). Although the averaged values of T1ρ and T2 were significantly correlated, they presented differences in spatial distribution and dynamic range, thus suggesting different sensitivities to tissue composition. This study suggests that T1ρ may be sensitive to early degenerative changes (corroborating previous studies) and clinical symptoms in intervertebral disc degeneration. Magn Reson Med 63:1193–1200, 2010. © 2010 Wiley‐Liss, Inc.