bluuebunny/crossref_metadata_2025 huggingface dataset:
Bacterial cytokinesis: From Z ring to divisome
Authors: Lutkenhaus Joe , Pichoff Sebastien , Du Shishen
Published: August 2012

Ancestral homologues of the major eukaryotic cytoskeletal families, tubulin and actin, play critical roles in cytokinesis of bacterial cells. FtsZ is the ancestral homologue of tubulin and assembles into the Z ring that determines the division plane. FtsA, a member of the actin family, is involved in coordinating cell wall synthesis during cytokinesis. FtsA assists in the formation of the Z ring and also has a critical role in recruiting downstream division proteins to the Z ring to generate the divisome that divides the cell. Spatial regulation of cytokinesis occurs at the stage of Z ring assembly and regulation of cell size occurs at this stage or during Z ring maturation. © 2012 Wiley Periodicals, Inc
Mid1/anillin and the spatial regulation of cytokinesis in fission yeast
Authors: Rincon Sergio A. , Paoletti Anne
Published: August 2012

Cell division is a critical and irreversible step in the cell cycle. The strategies that cells follow to regulate the position of the division plane must take into account the global geometry of the cell as well as position of the genetic material to ensure its accurate segregation into daughter cells of a given cell shape and size. Along the years, research on Schizosaccharomyces pombe, a well‐recognized model organism for cell division studies has allowed a detailed molecular understanding of the spatial mechanisms regulating cytokinesis. Division plane position in this unicellular rod‐shaped organism, which divides by the assembly and constriction of a medially placed actomyosin ring, largely depends on the anillin‐like protein Mid1. Therefore, the major pathways controlling the position of the division plane converge on Mid1. In this review, we make an overview of the studies that have deciphered how Mid1 localization and scaffolding activities are controlled over the cell cycle to ensure the symmetrical division of fission yeast cells. These studies have revealed new mechanisms generating spatial information based on nuclear shuttling of the division plane factor Mid1 and on the establishment of cortical inhibitory gradients of the cell polarity kinase Pom1. © 2012 Wiley Periodicals, Inc
Dipeptidyl Peptidase IV‐Activated Prodrugs of Anti‐Varicella Zoster Virus Bicyclic Nucleoside Analogues Containing Different Self‐Cleavage Spacer Systems
Authors: Diez‐Torrubia Alberto , Cabrera Silvia , De Meester Ingrid , Camarasa María‐José , Balzarini Jan , Velázquez Sonsoles
Published: August 2012

A new type of double prodrug of the antiviral family of bicyclic nucleoside analogues (BCNA) bearing cyclization self‐cleavage spacers between the Val‐Pro dipeptide sequence as well as the parent compound were synthesized and evaluated with regard to activation by the DPPIV/CD26 enzyme and for their stability in human and bovine serum. In buffer solution, carbamate and ester prodrugs were found to be chemically stable. Most prodrugs containing a dipeptidyl linker efficiently converted into the BCNA parent drug. In contrast, the Val‐Pro alkyldiamino prodrugs converted predominantly into their alkyldiamino prodrug intermediates in the presence of CD26 and human serum. A marked increase in water solubility was observed for all prodrugs. In contrast to the parent compound, a tetrapeptide prodrug containing the Val‐Val dipeptide as a self‐cleavage spacer released substantial amounts of the BCNA parent drug at the basolateral side of Caco‐2 cell cultures and exhibited 15‐ to 20‐fold increased bioavailability in mice relative to the poorly bioavailable parent compound.
Microlocal Analysis of the Geometric Separation Problem
Authors: Donoho David , Kutyniok Gitta
Published: August 2012

Image data are often composed of two or more geometrically distinct constituents; in galaxy catalogs, for instance, one sees a mixture of pointlike structures (galaxy superclusters) and curvelike structures (filaments). It would be ideal to process a single image and extract two geometrically “pure” images, each one containing features from only one of the two geometric constituents. This seems to be a seriously underdetermined problem but recent empirical work achieved highly persuasive separations.

We present a theoretical analysis showing that accurate geometric separation of point and curve singularities can be achieved by minimizing the ℓ1norm of the representing coefficients in two geometrically complementary frames: wavelets and curvelets. Driving our analysis is a specific property of the ideal (but unachievable) representation where each content type is expanded in the frame best adapted to it. This ideal representation has the property that important coefficients areclustered geometricallyin phase space, and that at fine scales, there is very little coherence between a cluster of elements in one frame expansion and individual elements in the complementary frame. We formally introduce notions ofcluster coherenceandclustered sparsityand use this machinery to show that the underdetermined systems of linear equations can be stably solved by ℓ1minimization; microlocal phase space helps organize the calculations that cluster coherence requires. © 2012 Wiley Periodicals, Inc.
Fragmentation reduces regional‐scale spatial genetic structure in a wind‐pollinated tree because genetic barriers are removed
Authors: Wang Rong , Compton Stephen G. , Shi Yi‐Su , Chen Xiao‐Yong
Published: August 2012

Gene flow strongly influences the regional genetic structuring of plant populations. Seed and pollen dispersal patterns can respond differently to the increased isolation resulting from habitat fragmentation, with unpredictable consequences for gene flow and population structuring. In a recently fragmented landscape we compared the pre‐ and post‐fragmentation genetic structure of populations of a tree species where pollen and seed dispersal respond differentially to forest fragmentation generated by flooding. Castanopsis sclerophylla is wind‐pollinated, with seeds that are dispersed by gravity and rodents. Using microsatellites, we found no significant difference in genetic diversity between pre‐ and post‐fragmentation cohorts. Significant genetic structure was observed in pre‐fragmentation cohorts, due to an unknown genetic barrier that had isolated one small population. Among post‐fragmentation cohorts this genetic barrier had disappeared and genetic structure was significantly weakened. The strengths of genetic structuring were at a similar level in both cohorts, suggesting that overall gene flow of C. sclerophylla has been unchanged by fragmentation at the regional scale. Fragmentation has blocked seed dispersal among habitats, but this appears to have been compensated for by enhanced pollen dispersal, as indicated by the disappearance of a genetic barrier, probably as a result of increased wind speeds and easier pollen movement over water. Extensive pollen flow can counteract some negative effects of fragmentation and assist the long‐term persistence of small remnant populations.
A New Design of Electrochemical and Optical Biosensors Based on Biocatalytic Growth of Au Nanoparticles – Example of Glucose Detection
Authors: Bourigua S. , Maaref A. , Bessueille F. , Renault N. Jaffrezic
Published: August 2012

A simple strategy for the design of glucose biosensors based on enzyme‐induced growth of gold nanoparticles (AuNPs) is proposed. It is for the first time applied for EIS and SPR glucose detection. AFM topography measurements proved that small spherical nanoparticles could grow on the enzyme‐modified surface after addition of glucose. The biosensor exhibits sensitive response to the analyte with a detection limit of 8 µM for the EIS (Electrochemical Impedance Spectroscopy) transduction and 10 µM for the SPR (Surface Plasmon Resonance) transduction associated to a rather large dynamic range: 0.008–4 mM and 0.01–7 mM, respectively. Moreover, the interbiosensor showed good reproducibility (RSD=8.3 %, n=4).
Improvement of the sensitivity of 2D LC‐MEKC separation of phenolic acids and flavonoids natural antioxidants using the on‐line preconcentration step
Authors: Česla Petr , Fischer Jan , Jandera Pavel
Published: August 2012

A 2D method was developed for separation of phenolic acids and flavonoids natural antioxidants combining LC with MEKC. The in‐capillary preconcentration step was applied for the improvement of the sensitivity of 2D method before the second dimension MEKC analysis. The influence of first dimension LC mobile phase composition on migration times in the second MEKC dimension was evaluated. When gradient elution is applied in the first dimension of 2D LC‐MEKC system, increasing concentration of organic solvent in the mobile phase and in fractions transferred from LC influences the electroosmotic flow, partitioning equilibria of samples in micelles and properties of the micelles, which results in shifts of migration times during the consecutive runs in the second MEKC separation dimension. The shifts of migration times caused by the influence of increasing concentration of ACN on MEKC separation in second dimension of 2D LC‐MEKC system were compensated by aligning the time axis using electroosmotic flow and micellar marker migration times. The optimized LC‐MEKC method was applied on the separation of natural antioxidants in the plant extracts samples.
An ALE finite element method for a coupled Stefan problem and Navier–Stokes equations with free capillary surface
Authors: Bänsch Eberhard , Paul Jordi , Schmidt Alfred
Published: August 2012

In this article, an ALE finite element method to simulate the partial melting of a workpiece of metal is presented. The model includes the heat transport in both the solid and liquid part, fluid flow in the liquid phase by the Navier–Stokes equations, tracking of the melt interface solid/liquid by the Stefan condition, treatment of the capillary boundary accounting for surface tension effects and a radiative boundary condition.

We show that an accurate treatment of the moving boundaries is crucial to resolve their respective influences on the flow field and thus on the overall energy transport correctly. This is achieved by a mesh‐moving method, which explicitly tracks the phase boundary and makes it possible to use a sharp interface model without singularities in the boundary conditions at the triple junction.

A numerical example describing the welding of a thin‐steel wire end by a laser, where all aforementioned effects have to be taken into account, proves the effectiveness of the approach.Copyright © 2012 John Wiley & Sons, Ltd.
Dynamic contrast‐enhanced MR perfusion imaging of head and neck tumors at 3 Tesla
Authors: Furukawa Matakazu , Parvathaneni Upendra , Maravilla Kenneth , Richards Todd L. , Anzai Yoshimi
Published: August 2012

Background

Dynamic contrast‐enhanced (DCE) MR perfusion imaging allows assessment of vascular density and integrity of tumors. The purpose of this study was to determine the diagnostic efficacy of time intensity curve analysis on DCE MRI for characterization of head and neck tumors.

Methods

Twenty patients underwent T1‐weighted fast field echo DCE MRI with temporal resolution of 2.6 seconds. In total, 100 dynamic phases covering 20 slices were obtained in 4.5 minutes. Time to peak (TTP), relative maximum enhancement (RME) ratio, and relative washout ratio (RWO) were calculated.

Results

Malignant tumors had a significantly lower RME (p = .025) and prolonged TTP with lower RWO than benign lesions. Postradiation changes had a significantly longer TTP (p = .024) and lower RWO (p = .007) than did postradiation recurrent tumors. Receiver operating characteristic (ROC) analysis revealed RWO had highest accuracy (area under the curve [AUC] = 1.0).

Conclusions

DCE MR perfusion imaging provides pivotal information regarding microcirculation, potentially improves differentiation of malignant tumor from postradiation changes. © 2012 Wiley Periodicals, Inc. Head Neck, 2013
Expression of the receptor tyrosine kinase recepteur d'origine nantais and its association with tumor progression in hypopharyngeal cancer
Authors: Yoon Tae Mi , Kim Sun‐Ae , Park Young‐Lan , Lee Kyung‐Hwa , Sung Myung‐Whun , Lee Joon Kyoo , Lim Sang Chul , Chung Ik‐Joo , Joo Young‐Eun
Published: August 2012

Background

The purpose of this study was to investigate expression of recepteur d'origine nantais (RON) in human hypopharyngeal squamous cell carcinoma (SCC) and to determine whether RON affects tumor cell behavior in hypopharyngeal SCC cell line and if this would serve as a target for molecular therapy in a preclinical model.

Methods

Reverse transcriptase‐polymerase chain reaction, immunohistochemistry, Western blotting, cell invasion, migration, proliferation, and apoptosis assays were used to assess alteration of RON expression and its impact to cancer progression in human hypopharyngeal SCC.

Results

Immunoreactivity of RON was observed in hypopharyngeal SCC tissues relative to adjacent normal mucosa in all cases. RON protein expression was significantly increased in metastatic lymph nodes than nonmetastatic lymph nodes by Western blotting. Knockdown of RON resulted in significantly reduced cell invasion, migration, and proliferation in human hypopharyngeal SCC cells. Knockdown of RON enhanced cell apoptosis through activation of caspase 3, caspase 7, and poly ADP‐ribose polymerase (PARP).

Conclusion

These results indicate that knockdown of RON expression may be associated with the reversal of invasive phenotype in hypopharyngeal SCC. © 2012 Wiley Periodicals, Inc. Head Neck, 2013
Raman spectroscopy provides a powerful, rapid diagnostic tool for the detection of tuberculous meningitis in ex vivo cerebrospinal fluid samples
Authors: Sathyavathi R. , Dingari Narahara Chari , Barman Ishan , Prasad P. S. R. , Prabhakar Subhashini , Narayana Rao D. , Dasari Ramachandra R. , Undamatla Jayanthi
Published: August 2012

In this letter, we propose a novel method for diagnosis of tuberculous meningitis using Raman spectroscopy. The silicate Raman signature obtained from Mycobacterium tuberculosis positive cases enables specific and sensitive detection of tuberculous meningitis from acquired cerebrospinal fluid samples. The association of silicates with the tuberculosis mycobacterium is discussed. We envision that this new method will facilitate rapid diagnosis of tuberculous meningitis without application of exogenous reagents or dyes and can be aptly used as a complementary screening tool to the existing gold standard methods. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Hyperosmotic induction of aquaporin expression in rat astrocytes through a different MAPK pathway
Authors: Yang Mei , Gao Fei , Liu Hui , Yu Wei Hua , Zhuo Fei , Qiu Guo Ping , Ran Jian Hua , Sun Shan Quan
Published: August 2012

Water homeostasis of the nervous system is important during neural signal transduction. Astrocytes are crucial in water transport in the central nervous system under both physiological and pathological conditions. To date, five aquaporins (AQP) have been found in rat brain astrocytes. Most studies have focused on AQP4 and AQP9, however, little is known about the expression of AQP3, ‐5, and ‐8 as well as their regulating mechanism in astrocytes. The expression patterns of AQP3, ‐5, and ‐8 in astrocytes exposed to hyperosmotic solutions were examined to clarify the roles of AQP3, ‐5, and ‐8 in astrocyte water movement. The expression of AQP4 and AQP9 under the same hyperosmotic conditions was also investigated. The AQP4 and AQP9 expressions continuously increased until 12 h after hyperosmotic solution exposure, whereas the AQP3, ‐5, and ‐8 expressions continued to increase until 6 h after hyperosmotic solution exposure. The different AQPs decreased at corresponding time points (24 h for AQP4 andAQP9; 12 h for AQP3, ‐5, and ‐8 after hyperosmotic solution exposure). The ERK inhibitor can attenuate the expression of AQP3, ‐5, and ‐8 after hyperosmotic solution exposure. The p38 inhibitor can inhibit the AQP4 and AQP9 expressions in cultured astrocytes. AQP expression is directly related to the extracellular hyperosmotic stimuli. Moreover, different AQPs can be regulated by a distinct MAPK signal transduction pathway. J. Cell. Biochem. 114: 111–119, 2012. © 2012 Wiley Periodicals, Inc.
Group Divisible Covering Designs with Block Size 4: A Type of Covering Array with Row Limit
Authors: Francetić Nevena , Danziger Peter , Mendelsohn Eric
Published: August 2012

A k‐GDCD, group divisible covering design, of type is a triple , where V is a set of gu elements, is a partition of V into u sets of size g, called groups, and is a collection of k‐subsets of V, called blocks, such that every pair of elements in V is either contained in a unique group or there is at least one block containing it, but not both. This family of combinatorial objects is equivalent to a special case of the graph covering problem and a generalization of covering arrays, which we call CARLs. In this paper, we show that there exists an integer such that for any positive integers g and , there exists a 4‐GDCD of type which in the worst case exceeds the Schönheim lower bound by δ blocks, except maybe when (1) and , or (2) , , and or . To show this, we develop constructions of 4‐GDCDs, which depend on two types of ingredients: essential, which are used multiple times, and auxiliary, which are used only once in the construction. If the essential ingredients meet the lower bound, the products of the construction differ from the lower bound by as many blocks as the optimal size of the auxiliary ingredient differs from the lower bound.
Economic production of Bacillus subtilis SPB1 biosurfactant using local agro‐industrial wastes and its application in enhancing solubility of diesel
Authors: Mnif Ines , Ellouze‐Chaabouni Semia , Ghribi Dhouha
Published: August 2012

BACKGROUND: The present work aimed to optimize a new economic medium for lipopeptide biosurfactant production by Bacillus subtilis SPB1 for application in the environmental field as an enhancer of diesel solubility. Statistical experimental designs and response surface methodology were employed to optimize the medium components.

RESULTS: A central composite design was applied to increase the production yield and predict the optimal values of the selected factors. An optimal medium, for biosurfactant production of about 4.5 g L−1, was found to be composed of sesame peel flour (33 g L−1) and diluted tuna fish cooking residue (40%) with an inoculum size of 0.22. Increased inoculum size (final OD600) significantly improved the production yield. The emulsifier produced was demonstrated to be an alternative to chemically synthesized surfactants since it shows high solubilization efficiency towards diesel oil in comparison with SDS and Tween 80.

CONCLUSION: Optimization studies led to a strong improvement in production yield. The emulsifier produced, owing its high solubilization capacity and its large tolerance to acidic and alkaline pH values and salinity, shows great potential for use in bioremediation processes to enhance the solubility of hydrophobic compounds. © 2012 Society of Chemical Industry
Exact Results on the Number of Restricted Edge Colorings for Some Families of Linear Hypergraphs
Authors: Lefmann Hanno , Person Yury
Published: August 2012

For k‐uniform hypergraphs F and H and an integer , let denote the number of r‐colorings of the set of hyperedges of H with no monochromatic copy of F and let , where the maximum is taken over the family of all k‐uniform hypergraphs on n vertices. Moreover, let be the usual extremal function, i.e., the maximum number of hyperedges of an n‐vertex k‐uniform hypergraph which contains no copy of F. Here, we consider the question for determining for F being the k‐uniform expanded, complete graph or the k‐uniform Fan(k)‐hypergraph with core of size , where , and we show

urn:x-wiley:03649024:jgt21653:equation:jgt21653-math-0011for and n large enough. Moreover, for or , for k‐uniform hypergraphs H on n vertices, the equality only holds if H is isomorphic to the ℓ‐partite, k‐uniform Turán hypergraph on n vertices, once n is large enough. On the other hand, we show that is exponentially larger than , if .
Comparison of antioxidant capacity and phenolic composition of peel and flesh of some apple varieties
Authors: Karaman Şeyda , Tütem Esma , Başkan Kevser Sözgen , Apak Reşat
Published: August 2012

BACKGROUND: Apples contain a large concentration of phenolic compounds, dependent on factors such as cultivar, harvest, storage conditions, and processing. This study aims to identify the essential phenolic compounds present in various apple varieties, to measure their total antioxidant capacity (TAC) with the CUPRAC (cupric ion reducing antioxidant capacity) and ABTS (2,2′‐azino‐bis(3‐ethylbenzothiazoline‐6‐sulfonate)) methods, and to correlate their TAC values with HPLC findings.

RESULTS: The order of TAC (mmol Trolox g−1 fresh weight) of apple peels determined with the CUPRAC method was: Granny Smith > Amasya > Sky Spur > Ervin Spur > King Luscious ≥ Arap Kizi ≥ Lutz Golden. The theoretically calculated TAC values of HPLC‐quantified compounds, with the aid of the combined HPLC‐CUPRAC method, accounted for 18.4–33.5% of the experimentally observed CUPRAC capacity of peel extracts and 19.5–56.3% of flesh extracts, depending on apple variety.

CONCLUSION: In synthetic samples of apple antioxidants, the CUPRAC‐TAC values of constituents, identified and analyzed by HPLC, proved to be additive, enabling measurement of the cooperative action of antioxidants using the proposed methodology. Apple peel showed higher contents of phenolics and therefore higher TAC than apple flesh, confirming the health benefit of the consumption of apples together with peel. © 2012 Society of Chemical Industry
Influence of maize flour particle size on gluten‐free breadmaking
Authors: de la Hera Esther , Talegón María , Caballero Pedro , Gómez Manuel
Published: August 2012

BACKGROUND: Maize, one of the suitable grains for coeliac consumption, is, together with rice, the most cultivated cereal in the world. However, the inclusion of maize flour in gluten‐free bread is a minority and studies are scarce. This paper analyses the influence of different maize flour types and their particle sizes on the quality of two types of bread without gluten (80% and 110% water in the formulation) obtained from them. We also analysed the microstructure of the dough and its behaviour during the fermentation.

RESULTS: Finer flours had a lower dough development during fermentation in all cases. Among the different types of flour, those whose microstructure revealed compact particles were those which had higher specific bread volume, especially when the particle size was greater. Among the formulations, the dough with more water gave breads with higher specific volume, an effect that was more important in more compact flours. The higher volume breads had lower values of hardness and resilience.

CONCLUSION: The type of corn flour and mainly its particle size influence significantly the dough development of gluten‐free bread during fermentation and therefore the final volume and texture of the breads obtained. The flours having coarser particle size are the most suitable for making gluten‐free maize bread. © 2012 Society of Chemical Industry
Meta‐analysis of the association between P53 codon 72 polymorphisms and gastric cancer
Authors: Zhang Qi , Ma Ying‐Yu , Wang Hui‐Ju , Shao Chang‐Ming , Zhang Jun , Ye Zai‐Yuan
Published: August 2012

Purpose

This meta‐analysis aims to examine whether the P53 codon 72 polymorphisms is associated with gastric cancer risk.

Methods

Pooled odds ratios (ORs) were appropriately derived from random‐effects models. Separate analyses were conducted on Asian and Caucasian populations. And a total of 21 studies were eligible (5,867 cases and 7,001 controls); 15 of them were conducted on Asians, others on Caucasians.

Results

The combined results based on all studies showed that there was significant difference in genotype distribution between gastric cancer and non‐cancer patients in the allele contrast (Pro vs. Arg); the codominant model (Pro/Pro vs. Arg/Arg) and the recessive model (Pro/Pro vs. Pro/Arg + Arg/Arg). When stratifying for race, patients with gastric cancer had a significantly higher frequency of Pro (OR = 1.136, 95% CI = 1.051–1.229), Pro/Pro (OR = 1.314, 95% CI = 1.110–1.555), Pro/Arg (OR = 1.099, 95% CI = 1.009–1.197), (Pro/Pro + Pro/Arg (OR = 1.153, 95% CI = 1.059–1.255) than non‐cancer patients among Asians. There was statistically significant heterogeneity across all included studies with the Q statistic and study population may be the most important factor contributed to the heterogeneity.

Conclusions

In conclusion, the P53 codon 72 polymorphisms seems to be associated with gastric cancer risk and the analyses suggested that P53 codon 72 polymorphisms may be an important biomarker of gastric cancer susceptibility for Asians. J. Surg. Oncol. 2013;107:360–366. © 2012 Wiley Periodicals, Inc.
Adrenal imaging: A primer for oncosurgeons
Authors: Goenka Ajit H. , Shah Shetal N. , Remer Erick M. , Berber Eren
Published: August 2012

Differentiation of an incidental adrenal lesion into benign and malignant etiologies is an endeavor with significant and obvious clinical benefit. Advances in imaging now enable this differentiation in high proportion of patients in a non‐invasive manner. The ACR guidelines elaborated in this review seek to promote clinically meaningful, evidence‐based approach to an IAL. Knowledge of the potential as well the limitations of individual modalities is essential so as to streamline investigations in a cost‐effective manner. J. Surg. Oncol. 2012; 106:543–548. © 2012 Wiley Periodicals, Inc.
Predictors of incidental gallbladder cancer in patients undergoing cholecystectomy for benign gallbladder disease
Authors: Koshenkov Vadim P. , Koru‐Sengul Tulay , Franceschi Dido , DiPasco Peter J. , Rodgers Steven E.
Published: August 2012

Background and Objectives

Discovery of incidental gallbladder cancer (IGC) has become more frequent due to adoption of laparoscopy. Gallbladder spillage during operation can disseminate cancer and worsen the prognosis.

Methods

Patients who underwent laparoscopic or open cholecystectomy for benign gallbladder disease January 1996 to August 2011 at two tertiary care facilities were reviewed. Unmatched controls were randomly selected in 2:1 ratio. Preoperative variables were compared between the two groups.

Results

Sixty‐seven patients with IGC were identified and compared to 134 controls. Mean age was 68 for index cases and 49 for controls; 70% of cases and 75% of controls were female. Multivariate analysis showed that higher risk of IGC was significantly associated with age ≥ 65 (OR = 10.61, P < 0.0001), dilated bile ducts (OR = 4.76, P = 0.0028), and presence of gallbladder wall thickening (OR = 4.39, P = 0.0003). This model yielded a very good area under the curve of receiver operating characteristic (AUC = 0.83) for discriminating the patients with IGC from controls.

Conclusions

IGC is more likely to be found in patients when age is ≥65, with dilated bile ducts and gallbladder wall thickening. Preoperative suspicion of gallbladder cancer should prompt the surgeon to be more careful not to perforate the gallbladder during laparoscopic approach, and to have a lower threshold for conversion if necessary. J. Surg. Oncol. 2013;107:118–123. © 2012 Wiley Periodicals, Inc.
First experiences of photoacoustic imaging for detection of melanoma metastases in resected human lymph nodes
Authors: Grootendorst D.J. , Jose J. , Wouters M.W. , van Boven H. , Van der Hage J. , Van Leeuwen T.G. , Steenbergen W. , Manohar S. , Ruers T.J.M.
Published: August 2012

Background and Objective

Excision and histological assessment of the first draining node (sentinel lymph node) is a frequently used method to assess metastatic lymph node involvement related to cutaneous melanoma. Due to the time required for accurate histological assessment, nodal status is not immediately available to the surgeon. Hence, in case histological examination shows metastases, the patient has to be recalled to perform additional lymphadenectomy. To overcome these drawbacks we studied the applicability of photoacoustic tomographic imaging as an intra‐operative modality for examining the status of resected lymph nodes.

Materials and Methods

In melanoma patients undergoing lymphadectomy for metastatic disease, six suspect lymph nodes were photoacoustically (PA) imaged using multiple wavelengths. Histopathologal examination showed three nodes without tumor cells (benign nodes) and three nodes with melanoma cells (malignant nodes). PA images were compared with histology and anatomical features were analyzed. In addition, PA spectral analysis was performed on areas of increased signal intensity.

Results

After correlation with histopathology, multiple areas containing melanoma cells could be identified in the PA images due to their increased response. Malignant nodes showed a higher PA response and responded differently to an increase in excitation wavelength than benign nodes. In addition, differences in anatomical features between the two groups were detected.

Conclusions

Photoacoustic detection of melanoma metastases based on their melanin content proves to be possible in resected human lymph nodes. The amount of PA signal and several specific anatomical features seem to provide additional characteristics for nodal analysis. However, it is as yet preliminary to designate a highly accurate parameter to distinguish between malignant and benign nodes. We expect to improve the specificity of the technique with a future implementation of an adjusted illumination scheme and depth correction for photon fluence. Lasers Surg. Med. 44: 541–549, 2012. © Wiley Periodicals, Inc.
Risk of cytomegalovirus disease in high-risk liver transplant recipients on valganciclovir prophylaxis: A systematic review and meta-analysis
Authors: Kalil Andre C. , Mindru Cezarina , Botha Jean F. , Grant Wendy J. , Mercer David F. , Olivera Marco A. , McCartan Megan A. , McCashland Timothy M. , Langnas Alan N. , Florescu Diana F.
Published: August 2012

Valganciclovir (VGC) was approved by the Food and Drug Administration in 2004 as cytomegalovirus (CMV) prophylaxis except for liver transplant recipients because of their high incidence of CMV disease with this drug. However, surveys have shown its common off-label use for CMV prophylaxis in liver transplant recipients. We aimed to evaluate the risk of CMV disease with VGC prophylaxis in liver transplant recipients. All studies that evaluated liver transplant recipients and used VGC (900 or 450 mg daily) for the prevention of CMV disease were included. Five controlled studies (n = 483) were pooled with a random effects model; five single-arm studies (n = 380) were pooled for the prevalence rate of CMV disease. The risk of CMV disease with VGC versus ganciclovir was 1.81 [95% confidence interval (CI) = 1.00-3.29, P = 0.05, I
2 = 0%]. For high-risk (donor-positive/recipient-negative) patients, the risk of CMV disease was 1.96 (95% CI = 1.05-3.67, P = 0.035, I
2 = 0%). The risk of CMV disease remained significant with 900 mg of VGC daily (P = 0.04) but not with 450 mg of VGC daily (P = 0.76). The risk of leukopenia with VGC was 1.87 (95% CI = 1.03-3.37, P = 0.04, I
2= 0%). In single-arm trials, the overall CMV disease rate was 12% (95% CI = 9%-16%, P < 0.001), and the rate for high-risk patients was 20% (95% CI = 10%-38%, P = 0.002). In conclusion, 900 mg of VGC daily may not be safe as CMV prophylaxis in high-risk liver transplant recipients because of the significant 2-fold increase in the risk of CMV disease and the 1.9-fold increase in the risk of leukopenia. Alternative CMV prophylaxis should be used for liver transplant recipients. Liver Transpl, 2012. © 2012 AASLD.
Thermoresponsive Aggregation Behavior of Triterpene–Poly(ethylene oxide) Conjugates in Water
Authors: Zhao Junpeng , Jeromenok Jekaterina , Weber Jens , Schlaad Helmut
Published: August 2012

Bioconjugate amphiphiles comprising triterpene and poly(ethylene oxide) (PEO) were studied according to their thermoresponsive aggregation behavior (LCST) in water. Cholesteryl−PEO (CE) and betulinyl−PEO (BE) comprising <70 wt% PEO precipitated from water upon heating. CE, but not BE, solutions contained nanoscopic aggregates at room temperature causing different thermoprecipitation behaviors. Solutions containing 5 wt% solutions of BE with short PEO chains demonstrated dual thermoresponsive behavior, precipitating at high temperature and forming hydrogel at low temperature. A BE multiblock copolymer was found to form large aggregates, presumably vesicles, in water. Results suggest that the solution properties of triterpene–PEO amphiphiles can be controlled by the chemical composition and structure.

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Polylactide Block Copolymers using Trimethylene Carbonate with Methoxyethoxy Side Groups for Dual Modification of Hydrophilicity and Biodegradability
Authors: Ajiro Hiroharu , Takahashi Yoshikazu , Akashi Mitsuru , Fujiwara Tomoko
Published: August 2012

Novel block copolymers using the monomers 5‐(2‐methoxyethyoxymethyl)‐5‐methyl‐[1,3]‐dioxa‐2‐one (TMCM‐MOE1OM) as a hydrophilic segment and lactides as a hydrophobic segment were designed in order to prepare controllable degradation polymers by dynamic polymer rearrangement based on the hydrophilicity. When the copolymer film contacted water, the hydrophobic polylactide (PLA) segments tend to be buried under the TMCM‐MOE1OM segments due to the hydrophilicity of the methoxyethoxy groups. The copolymers were hardly degraded by both proteinase K and lipase, while both of their homopolymers, poly(trimethylene carbonate) and PLA, were degraded, which suggests that the rearrangement of the TMCM‐MOE1OM segments at the outermost surface significantly improved the degradation ratio.

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The Construction of a Low‐Cost Airline Network – Facing Competition and Exploring New Markets
Authors: Müller Kathrin , Hüschelrath Kai , Bilotkach Volodymyr
Published: August 2012

The paper investigates the construction of a low‐cost airline network by analyzing JetBlue Airways' entry decisions into non‐stop domestic US airport‐pair markets. Adopting duration models, we find that JetBlue consistently avoided concentrated airports and targeted concentrated routes; network economies also affected entry positively. For non‐stop entry into routes that have not been served directly before, our analysis reveals that the carrier focused on thicker routes and secondary airports. Non‐stop entry into existing non‐stop markets, however, shows that JetBlue concentrated on longer‐haul markets and avoided routes already operated by either other low‐cost carriers or network carriers under bankruptcy protection. Copyright © 2012 John Wiley & Sons, Ltd.
Background‐free solution boron NMR spectroscopy
Authors: Király Péter
Published: August 2012

The appearance of background signals arising from the NMR probe and tube is a well‐known problem of boron NMR spectroscopy. Background suppression may be achieved by using DEPTH, which increases the signal‐to‐background (S/B) ratio. Although, the quality of such spectra is often adequate, but in the case of rapid relaxation broadened resonances (T1 < 1 ms), the residual background signals may still hamper the interpretation of the spectra. It was observed that the background signals are practically invisible in solution 10B NMR. The unusual isotopic effect on the (S/B) ratio was interpreted as an inherent consequence of the integer versus half‐integer spin of 10B and 11B, respectively. The practicability of 10/11B NMR was compared for a selected set of boron compounds covering the typical range of (S/B) ratio. The application of 11B is more favourable than 10B as long as it is possible to achieve the desired spectral quality by using DEPTH. Otherwise, the ‘background‐free’ appearance of 10B NMR spectra makes 10B a reasonable alternative of 11B DEPTH. This was found typical for compounds having relaxation broadened resonances. The variable temperature (VT) NMR study of an adduct formation process was also presented here as an example of the advantage of 10B over 11B. Copyright © 2012 John Wiley & Sons, Ltd.
Fast access to residual dipolar couplings by single‐scan 2D NMR in oriented media
Authors: Giraudeau Patrick , Montag Tobias , Charrier Benoît , Thiele Christina M.
Published: August 2012

Residual dipolar couplings (RDCs) have revolutionized the structure determination of biomolecular and organic compounds. So far, their measurement has been rather time‐consuming, but one might imagine that RDCs can one day also be useful in the investigation of compounds with limited stability or short lifetimes. For such applications, it is indispensable to shorten the experiment time. In this communication, we show the first measurement of RDCs from single‐scan two‐dimensional NMR. An ultrafast HSQC NMR pulse sequence is presented, which includes several of the recent improvements brought to ultrafast NMR in terms of sensitivity, resolution, and spectral width. Ultrafast spectra are obtained in as little time as 60 s on an organic compound at natural abundance, namely (+)‐isopinocampheol. When extracting the RDCs from these ultrafast data, a good agreement with those extracted from conventional spectra (obtained in a much longer time) is observed. These results point out the efficiency of the ultrafast approach, particularly when considering the total experiment duration. Copyright © 2012 John Wiley & Sons, Ltd.
Sparsity transform k‐t principal component analysis for accelerating cine three‐dimensional flow measurements
Authors: Knobloch Verena , Boesiger Peter , Kozerke Sebastian
Published: August 2012

Time‐resolved three‐dimensional flow measurements are limited by long acquisition times. Among the various acceleration techniques available, k‐t methods have shown potential as they permit significant scan time reduction even with a single receive coil by exploiting spatiotemporal correlations. In this work, an extension of k‐t principal component analysis is proposed utilizing signal differences between the velocity encodings of three‐directional flow measurements to further compact the signal representation and hence improve reconstruction accuracy. The effect of sparsity transform in k‐t principal component analysis is demonstrated using simulated and measured data of the carotid bifurcation. Deploying sparsity transform for 8‐fold undersampled simulated data, velocity root‐mean‐square errors were found to decrease by 52 ± 14%, 59 ± 11%, and 16 ± 32% in the common, external, and internal carotid artery, respectively. In vivo, errors were reduced by 15 ± 17% in the common carotid artery with sparsity transform. Based on these findings, spatial resolution of three‐dimensional flow measurements was increased to 0.8 mm isotropic resolution with prospective 8‐fold undersampling and sparsity transform k‐t principal component analysis reconstruction. Volumetric data were acquired in 6 min. Pathline visualization revealed details of helical flow patterns partially hidden at lower spatial resolution. Magn Reson Med, 2013. © 2012 Wiley Periodicals, Inc.
3D phase unwrapping using global expected phase as a reference: Application to MRI global shimming
Authors: Liu Wentao , Tang Xin , Ma Yajun , Gao Jia‐Hong
Published: August 2012

MRI phase data often suffers from phase wrapping (i.e., phase may be discontinuous by 2π jumps). Numerous MRI phase unwrapping strategies were developed in the past using a criterion based on phase information of local or neighboring voxels. In this study, an alternative and novel three dimensional phase unwrapping strategy is introduced. This method considers the global character of the phase distribution and utilizes continuous trigonometric functions to construct an expected phase map as an unwrapping reference, which is then used to guide the phase correction of every individual voxel. The original phase is estimated by analyzing the derivative of the wrapped phase image. Simulations of various phase wrapped situations were performed and this new method was also used for an in vivo application (i.e., MRI automatic global shimming). Both simulated and experimental results demonstrate that our proposed method is more reliable and robust than traditional algorithms at obtaining correct phase maps, especially in regions of low‐signal and air cavities, such as the abdomen and pelvis. Magn Reson Med, 2013. © 2012 Wiley Periodicals, Inc.
Design and evaluation of a detunable water‐based quadrature HEM11 mode dielectric resonator as a new type of volume coil for high field MRI
Authors: Aussenhofer Sebastian A. , Webb Andrew G.
Published: August 2012

An annular dielectric resonator made from distilled water has been designed to operate in degenerate quadrature HEM11 modes at 298.1 MHz (7 Tesla). The circularly polarized B field has a high degree of homogeneity throughout a sample placed within the annulus. The sensitivity of the resonator was measured to be essentially identical to that of an eight‐rung high‐pass birdcage resonator with the same physical dimensions. High resolution in vivo images have been obtained from the human wrist. A new method of electronically detuning the resonator has also been evaluated. The design is extremely simple and rapid to build, with direct applicability to very high field imaging and also potential integration into human and animal hybrid position emission tomography (PET)/MRI and single‐photon emission computed tomography (SPECT)/MRI systems due to the lack of conductor attenuation‐induced artifacts in the reconstructed nuclear medicine images. Magn Reson Med, 2012. © 2012 Wiley Periodicals, Inc.
Metabolic imaging of multiple X‐nucleus resonances
Authors: Steinseifer Isabell K. , Wijnen Jannie P. , Hamans Bob C. , Heerschap Arend , Scheenen Tom W. J.
Published: August 2012

This study describes a technique for fast imaging of x‐nuclei metabolites. Due to increased sensitivity and larger chemical shift dispersion at high magnetic fields, images of multiple metabolites can be obtained simultaneously by selective excitation of their resonances with a multifrequency selective radiofrequency pulse at any desired flip angle. This aim is achieved by combining a three‐dimensional gradient echo imaging sequence with a Shinnar‐LeRoux optimized excitation pulse. A proper choice of bandwidth, imaging matrix size, and field of view allows using the chemical shift dispersion of the different resonances to completely separate their images within one large field of view. The method of fast metabolic imaging is illustrated with 13C measurements of a phantom containing a solution of 13C labeled glucose, lactate, and sodium octanoate and by dynamic measurements of the 31P metabolites phosphocreatine and β‐adenosine triphosphate in human femoral muscle in vivo, both at 7T. With dynamic selective 31P imaging of the larger part of the upper leg, phosphocreatine signal intensity changes of specific muscles can be studied simultaneously by analyzing the sum of phosphocreatine signals within arbitrarily shaped regions of interest following the muscles' contours. This concept of dynamic metabolic imaging can be applied to other organs and further expanded to other MR‐detectable nuclei and metabolites. Magn Reson Med, 2013. © 2012 Wiley Periodicals, Inc.
Modeling the behavior of sandstone based on generalized plasticity concept
Authors: Weng Meng‐Chia , Ling Hoe I.
Published: August 2012

With the concept of generalized plasticity, a constitutive model for describing the deformation behavior of sandstone is proposed in this paper. This proposed model is characterized by the following features: (i) nonlinear elasticity under hydrostatic and shear loading; (ii) associated flow rule for pre‐peak simulation; (iii) substantial plastic deformation during shear loading; and (iv) significant shear dilation and distortion prior to the failure state. This model requires 10 material parameters, including three for elasticity and seven for plasticity. All of the parameters can be determined, in a straightforward manner, by the suggested procedures. The proposed model has been validated by comparing the triaxial test results of the Mushan sandstone under different hydrostatic stress, different stress paths, and cyclic loading condition. It is also versatile in simulating the deformation behaviors of two other sandstones. Upon slight modification of the model, the post‐peak behavior of sandstone can be reasonably predicted using proposed model. Copyright © 2012 John Wiley & Sons, Ltd.
Linear Enamel Hypoplasia and Age‐at‐Death at Medieval (11th–16th Centuries) St. Gregory's Priory and Cemetery, Canterbury, UK
Authors: Miszkiewicz Justyna Jolanta
Published: August 2012

Linear enamel hypoplasia (LEH) is a macroscopically detectable band‐like dental defect, which represents localized decrease in enamel thickness caused by some form of disruption to a child's health. Such dental deformations are utilized in osteoarchaeological research as permanent markers of childhood physiological stress and have been extensively studied in numerous ancient human populations. However, currently there is no such data for medieval populations from Canterbury, UK. Here, LEH is examined in the context of age‐at‐death in human burials from the medieval St. Gregory's Priory and adjacent cemetery (11th–16th centuries), Canterbury, UK. The cemetery and Priory burials represented lower (n = 30) and higher status (n = 19) social groups, respectively.

Linear enamel hypoplastic defects were counted on mandibular and maxillary anterior permanent teeth (n = 374). The age and sex of each skeleton were estimated using standard methods. Differences in LEH counts, age‐at‐death, and LEH formation ages were sought between the two social groups. Results indicate significantly greater frequencies of LEH in the Cemetery (mean = 17.6) compared to the Priory (mean = 7.9; t = −3.03, df = 46, p = 0.002). Adult age‐at‐death was also significantly lower in the Cemetery (mean = 39.8 years) compared to the Priory burials (mean = 44.1 years; t = 2.275, df = 47, p = 0.013). Hypoplasia formation ages differed significantly between the Priory (mean = 2.49 years) and Cemetery (mean = 3.22 years; t = 2.076; df = 47; p = 0.034) individuals.

Results indicate that childhood stress may reflect adult mortality in this sample, and that the wellbeing of individuals from diverse social backgrounds can be successfully assessed using LEH analyses. Results are discussed in terms of the multifactorial etiology of LEH, as well as weaning‐related LEH formation. Copyright © 2012 John Wiley & Sons, Ltd.
Synthesis and characterization of polypyrrole‐platinum composite for use as electrode material
Authors: Jayasree R. , Chandrasekar R. , Cindrella L.
Published: August 2012

Synthesis and characterization of polypyrrole (PPy) supported platinum by a simple method is reported in this study. The porous structure of PPy and its tendency for doping with acids prompted us to utilize this property to incorporate platinum by adsorption followed by reduction on the PPy matrix. Dispersed platinum electro catalyst on the conducting PPy support provides favorable reaction site for redox reactions in electrochemical devices such as hydrox fuel cell. The mesoporous matrix of PPy as revealed by FESEM could facilitate effective contact between the reactant gases and electro catalyst. The cauliflower like structure of the PPy matrix could enhance the electrochemical active surface area of the catalyst. The composite material is characterized by cyclic voltammetry (CV), polarization study, four probe technique, density and porosity study. The CV highlights the use of PPy‐Pt hybrid as a capacitor and the Tafel plot infers on the high exchange current density of the hybrid material. POLYM. COMPOS. 2012. © 2012 Society of Plastics Engineers