bluuebunny/crossref_metadata_2025_split huggingface dataset:
In Vitro Reconstitution of a PKS Pathway for the Biosynthesis of Galbonolides in Streptomyces sp. LZ35
Authors: Liu Chao , Zhu Jing , Li Yaoyao , Zhang Juanli , Lu Chunhua , Wang Haoxin , Shen Yuemao 
Published: March 2015

AbstractThe galbonolides are 14‐membered macrolide antibiotics with a macrocyclic backbone similar to that of erythromycins. Galbonolides exhibit broad‐spectrum antifungal activities. Retro‐biosynthetic analysis suggests that the backbone of galbonolides is assembled by a type I modular polyketide synthase (PKS). Unexpectedly, the galbonolide biosynthetic gene cluster, gbn, in Streptomyces sp. LZ35 encodes a hybrid fatty acid synthase (FAS)‐PKS pathway. In vitro reconstitution revealed the functions of GbnA (an AT‐ACP didomain protein), GbnC (a FabH‐like enzyme), and GbnB (a novel multidomain PKS module without AT and ACP domains) responsible for assembling the backbone of galbonolides, respectively. To our knowledge, this study is the first biochemical characterization of a hybrid FAS‐PKS pathway for the biosynthesis of 14‐membered macrolides. The identification of this pathway provides insights into the evolution of PKSs and could facilitate the design of modular pools for synthetic biology.
Chemical versus Electrochemical Synthesis of Carbon Nano‐onion/Polypyrrole Composites for Supercapacitor Electrodes
Authors: Mykhailiv Olena , Imierska Monika , Petelczyc Martyna , Echegoyen Luis , Plonska‐Brzezinska Marta E. 
Published: March 2015

AbstractThe development of high‐surface‐area carbon electrodes with a defined pore size distribution and the incorporation of pseudo‐active materials to optimize the overall capacitance and conductivity without destroying the stability are at present important research areas. Composite electrodes of carbon nano‐onions (CNOs) and polypyrrole (Ppy) were fabricated to improve the specific capacitance of a supercapacitor. The carbon nanostructures were uniformly coated with Ppy by chemical polymerization or by electrochemical potentiostatic deposition to form homogenous composites or bilayers. The materials were characterized by transmission‐ and scanning electron microscopy, differential thermogravimetric analyses, FTIR spectroscopy, piezoelectric microgravimetry, and cyclic voltammetry. The composites show higher mechanical and electrochemical stabilities, with high specific capacitances of up to about 800 F g−1 for the CNOs/SDS/Ppy composites (chemical synthesis) and about 1300 F g−1 for the CNOs/Ppy bilayer (electrochemical deposition).
Recent Developments in the Trifluoromethylation of Alkynes
Authors: Gao Pin , Song Xian‐Rong , Liu Xue‐Yuan , Liang Yong‐Min 
Published: March 2015

AbstractIn the last few years, the development of versatile methodologies to incorporate trifluoromethyl groups into organic molecules has attracted significant attention in synthetic chemistry. This review gives an overview over the development on the trifluoromethylation of alkynes, which have not been solely discussed before. Formation of diverse C(sp, sp2, sp3)CF3 bonds are all covered in this review.
Potential of Sustainable Hierarchical Zeolites in the Valorization of α‐Pinene
Authors: Nuttens Nicolas , Verboekend Danny , Deneyer Aron , Van Aelst Joost , Sels Bert F. 
Published: March 2015

AbstractIn the valorization of α‐pinene, which is an important biomass intermediate derived from turpentine oil, hierarchical (mesoporous) zeolites represent a superior class of catalysts. Hierarchical USY, ZSM‐5, and beta zeolites have been prepared, characterized, and catalytically evaluated, with the aim of combining the highest catalytic performance with the most sustainable synthetic protocol. These zeolites are prepared by alkaline treatment in aqueous solutions of NH4OH, NaOH, diethylamine, and NaOH complemented with tetrapropylammonium bromide. The hierarchical USY zeolite is the most attractive catalyst of the tested series, and is able to combine an overall organic‐free synthesis with an up to sixfold activity enhancement and comparable selectivity over the conventional USY zeolite. This superior performance relates to a threefold greater activity than that of the commercial standard, namely, H2SO4/TiO2. Correlation of the obtained benefits to the amount of solid lost during the postsynthetic modifications highlights that the highest activity gains are obtained with minor leaching. Furthermore, a highly zeolitic character, as determined by bulk XRD, is beneficial, but not crucial, in the conversion of α‐pinene. The alkaline treatments not only result in a higher overall activity, but also a more functional external surface area, attaining up to four times the pinene conversions per square nanometer. The efficiency of the hierarchical USY zeolite is concomitantly demonstrated in the conversion of limonene and turpentine oil, which emphasizes its industrial potential.
Up‐Scaled Microspherical Aggregates of LiFe0.4V0.4PO4/C Nanocomposites as Cathode Materials for High‐Rate Li‐Ion Batteries
Authors: Yu Feng , Qi Peirong , An Yongxin , Wang Gang , Xia Lili , Zhu Mingyuan , Dai Bin 
Published: March 2015

AbstractA series of microspherical LiFexV2/3−2x/3PO4/C (0<x<1) composites are successfully prepared using spray drying and the carbothermal reduction method. Compared with Li3V2(PO4)3/C and LiFePO4/C, LiFe0.4V0.4PO4/C is a solid solution and has a microspherical morphology. The LiFe0.4V0.4PO4/C microspheres with an essentially log‐normal distribution around 18.2 μm consist of nanosized LiFe0.4V0.4PO4/C particles as building blocks, which have an average size of around 50 nm, a specific surface area of 11.3 m2 g−1, and a Barrett–Joyner–Halenda pore diameter of 21.9 nm. Moreover, LiFe0.4V0.4PO4/C delivers a discharge capacity of 144.8 mAh g−1 at C/10, which is close to the theoretical discharge capacity of 148.2 mAh g−1 in the insertion/extraction process at 2.5–4.3 V. Even at 10C and 20C, LiFe0.4V0.4PO4/C shows excellent specific capacities of 125.2 and 119.6 mAh g−1, respectively, corresponding to excellent rate capacity retentions of close to 86.5 % and 82.6 %, respectively.
The neural correlates of volitional attention: A combined fMRI and ERP study
Authors: Bengson Jesse J. , A. Kelley Todd , Mangun George R. 
Published: March 2015

AbstractStudies of visual‐spatial attention typically use instructional cues to direct attention to a relevant location, but in everyday vision, attention is often focused volitionally, in the absence of external signals. Although investigations of cued attention comprise hundreds of behavioral and physiological studies, remarkably few studies of voluntary attention have addressed the challenging question of how spatial attention is initiated and controlled in the absence of external instructions, which we refer to as willed attention. To explore this question, we employed a trial‐by‐trial spatial attention task using electroencephalography and functional magnetic resonance imaging (fMRI). The fMRI results reveal a unique network of brain regions for willed attention that includes the anterior cingulate cortex, left middle frontal gyrus (MFG), and the left and right anterior insula (AI). We also observed two event‐related potentials (ERPs) associated with willed attention; one with a frontal distribution occurring 250–350 ms postdecision cue onset (EWAC: Early Willed Attention Component), and another occurring between 400 and 800 ms postdecision‐cue onset (WAC: Willed Attention Component). In addition, each ERP component uniquely correlated across subjects with different willed attention‐specific sites of BOLD activation. The EWAC was correlated with the willed attention‐specific left AI and left MFG activations and the later WAC was correlated only with left AI. These results offer a comprehensive and novel view of the electrophysiological and anatomical profile of willed attention and further illustrate the relationship between scalp‐recorded ERPs and the BOLD response. Hum Brain Mapp 36:2443–2454, 2015. © 2015 Wiley Periodicals, Inc.
Reproductive Hormones and Longitudinal Change in Bone Mineral Density and Incident Fracture Risk in Older Men: The Concord Health and Aging in Men Project
Authors: Hsu Benjumin , Cumming Robert G , Seibel Markus J , Naganathan Vasi , Blyth Fiona M , Bleicher Kerrin , Dave Aneesh , Le Couteur David G , Waite Louise M , Handelsman David J 
Published: March 2015

ABSTRACT

The objectives of this study were to examine relationships between baseline levels of reproductive hormones in older men and (1) change in bone mineral density (BMD) over 5 years and (2) incident fractures over an average of 6 years' follow-up. A total of 1705 men aged 70 years and older from the Concord Health and Ageing in Men Project (CHAMP) study were assessed at baseline (2005–2007), 2 years follow-up (2007–2009), and 5 years follow-up (2010–2013). At baseline, testosterone (T), dihydrotestosterone (DHT), estradiol (E2), and estrone (E1) were measured by liquid chromatography–tandem mass spectrometry (LC-MS/MS), and sex hormone–binding globulin (SHBG), luteinizing hormone (LH), and follicle-stimulating hormone (FSH) by immunoassay. Hip BMD was measured by dual X-ray absorptiometry (DXA) at all three time-points. Fracture data were collected at 4-monthly phone calls and verified radiographically. Statistical modeling was by general estimating equations and Cox model regression. Univariate analyses revealed inverse associations for serum SHBG, FSH, and LH and positive association for E1 but not DHT or E2 with BMD loss at the hip across the three time points. Serum levels of SHBG (β = –0.071), FSH (β = –0.085), LH (β = –0.070), and E1 (β = 0.107) remained significantly associated with BMD loss in multivariate-adjusted models; however, we were unable to identify any thresholds for accelerated BMD loss according to reproductive steroids. Incident fractures (all, n = 171; hip, n = 44; and nonvertebral, n = 139) were all significantly associated with serum SHBG, FSH, and LH levels in univariate models but none remained significantly associated in multivariate-adjusted model. Serum T, DHT, E2, and E1 levels were not associated with incident fractures in univariate or multivariate-adjusted analyses. In older men, lower serum SHBG, FSH, and LH and higher E1 levels protected against loss of BMD without increasing fracture rate. This means these reproductive variables may be considered as novel biomarkers of bone health during male aging. © 2015 American Society for Bone and Mineral Research.
Investigation of Paclitaxel Resistant R306C Mutation in β‐Tubulin—A Computational Approach
Authors: Verma Kanika , Ramanathan K. 
Published: March 2015

ABSTRACTPaclitaxel is the most effective chemotherapeutic agent used for the treatment of a broad spectrum of solid tumors. However, observed paclitaxel resistance in clinical trials presents one of the major obstacles for cancer chemotherapy. Most importantly, resistance due to β‐tubulin mutations (R306C) has been intensely debated in recent years. Despite all efforts, mechanism of resistance is still not well understood. In this study, computational techniques were employed to uncover the effect of R306C mutation in the β‐tubulin structure and its function. The tools such as I‐Mutant, CUPSAT and Fold‐X were employed to address the consequence of R306C mutation in the structural stability of β‐tubulin. Further, molecular docking and molecular dynamics study was employed to understand the functional impact of β‐tubulin mutation. Our results suggest that the R306C mutation causes a significant reduction in the binding affinity between β‐tubulin and paclitaxel. Further, docked complex analysis indicates that destruction of conservative hydrogen bond maintained by the residues Arg282 and Gly360 should be responsible for the large conformation changes of the binding pocket in R306C mutant. Finally, molecular dynamics simulations study confirms the stable binding of paclitaxel with native type β‐tubulin structure rather than mutant (R306C) type. We certainly believe that this study will provide useful guidance for the development of novel inhibitors that are less susceptible to drug resistance. J. Cell. Biochem. 116: 1318–1324, 2015. © 2015 Wiley Periodicals, Inc.
Mammary Branching Morphogenesis Requires Reciprocal Signaling by Heparanase and MMP‐14
Authors: Gomes Angélica Maciel , Bhat Ramray , Correia Ana Luísa , Mott Joni D. , Ilan Neta , Vlodavsky Israel , Pavão Mauro S.G. , Bissell Mina 
Published: March 2015

ABSTRACTThe development of the mammary gland involves formation of a branched arboreal structure resulting from the penetration and proliferation of epithelial cells into the fat pad. The mammary cells invade by remodeling their surrounding extracellular matrix (ECM), which are rich in proteins, and glycans such as heparan sulfate proteoglycans (HSPGs). There is increasing literature on how the interaction between signaling by ECM and matrix metalloproteinases (MMPs) is relevant to morphogenetic and physiological contexts. Here we sought to understand how heparanase, the sole mammalian heparan sulfate‐degrading endoglycosidase may regulate mammary gland development. We found a robust localization of heparanase within growing end buds during branching in vivo. Using three‐dimensional (3D) organotypic cultures, we showed that heparanase expression and activity are required for mammary epithelial invasion/branching within dense collagen I gels. Morphometric analysis of glands from both heparanase‐overexpressing and knockout mice showed a direct correlation between degree of branching and the heparanase levels, confirming our 3D organotypic culture observations. Finally, we uncovered a reciprocal association between levels of heparanase and MMP14, a membrane‐bound MMP, shedding further light on how branching occurs within developing mammary glands. J. Cell. Biochem. 116: 1668–1679, 2015. © 2015 Wiley Periodicals, Inc.
PTEN Inhibits High Glucose‐Induced Phenotypic Transition in Podocytes
Authors: Xing Lingling , Liu Qingjuan , Fu Shuxia , Li Shaomei , Yang Lin , Liu Shuxia , Hao Jun , Yu Lianying , Duan Huijun 
Published: March 2015

ABSTRACTAccumulating evidence has suggested that podocytes undergo epithelial–mesenchymal transition (EMT) in diabetic nephropathy (DN). However, the underlying mechanisms of EMT in podocyte are not well understood. PI3K/Akt pathway is involved in the progression of DN. In the present study, we demonstrated that PI3K/Akt pathway was activated in podocytes exposed to high glucose conditions, accompanied by down‐regulation of the podocalyxin (PCX) and nephrin expression and up‐regulation of the desmin and α‐smooth muscle actin (α‐SMA) expression. Inhibition of PI3K/Akt pathway by chemical LY294002 or Phosphase and tensin homology deleted on chromosome ten (PTEN) prevented the phenotypic transition. These findings indicate that PTEN/PI3K/Akt pathway mediates high glucose‐induced phenotypic transition in podocytes. J. Cell. Biochem. 116: 1776–1784, 2015. © 2015 Wiley Periodicals, Inc.
Sirt1 Regulates Microtubule Dynamics Through Negative Regulation of Plk1 in Mitosis
Authors: Kim Jin‐Ju , Gil Na‐Yeon , Zhang Xiang Hua , Chun Kwang‐Hoon , Fang Guowei , Kim Joon , Cho Hyeseong , Jang Chang‐Young , Cha Hyuk‐Jin 
Published: March 2015

ABSTRACTAlthough loss of Sirt1 leads to chromosome aneuploidy, which accounts for higher tumor susceptibility, the molecular mechanisms remain unclear. Herein, we demonstrate that Sirt1 directly regulates Plk1, of which activity is critical for mitotic progression and spindle dynamics. Depletion or inhibition of Sirt1 significantly perturbs the formation of the mitotic spindle, leading to defective chromosome segregation. Elevated depolymerization of the mitotic spindle following loss of Sirt1 was associated with the deregulation of Plk1 activity. Thus, we conclude that Sirt1 may contribute to a mitotic regulator that controls spindle dynamics through Plk1 activity, resulting in fine‐tuning of Plk1 dependent microtubule dynamics. J. Cell. Biochem. 116: 1888–1897, 2015. © 2015 Wiley Periodicals, Inc.
Synthesis of a Platinum Diketonate‐Containing Polymer Showing Oxygen‐Resistant Phosphorescence
Authors: Tanaka Kazuo , Hirose Amane , Tamashima Kenji , Chujo Yoshiki 
Published: March 2015

The synthesis of a platinum diketonate‐based alternating copolymer containing a fluorene unit and its oxygen‐resistant phosphorescence are reported. The polymerization is executed via palladium‐catalyzed Suzuki−Miyaura coupling reaction. The synthesized polymer shows good solubility in common organic solvents and processability to form homogeneous films. By optical measurements it is found that the synthesized polymer shows phosphorescence from a triplet π–π* ligand‐centered transition, and interestingly, the emission is hardly influenced by oxygen. Phosphorescence is observed from both solution and film samples under aerobic conditions. The new idea of obtaining emissive materials based on conjugated polymers showing oxygen‐resistant phosphorescence is presented here.
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Maternal high‐salt diets affected pressor responses and microvasoconstriction via PKC/BK channel signaling pathways in rat offspring
Authors: Bo Le , Jiang Lin , Zhou Anwen , Wu Chonglong , Li Jiayue , Gao Qinqin , Zhang Pengjie , Lv Juanxiu , Li Na , Gu Xiuxia , Zhu Zhoufeng , Mao Caiping , Xu Zhice 
Published: March 2015

ScopeHigh‐salt (HS) intake is linked to hypertension, and prenatal exposure to maternal HS diets may have long‐term impact on cardiovascular systems. The relationship between HS diets and cardiovascular disease has received extensive attention. This study determined pressor responses and microvessel functions in the adult offspring rats exposed to prenatal HS.Methods and resultsThe offspring of 5‐month old as young adults in rats were used. Blood pressure, vascular tone, intracellular Ca2+, and BK channels in mesenteric arteries were measured in the offspring. Phenylephrine (Phe)‐induced pressor responses were significantly higher in the prenatal HS offspring. Vessel tension and intracellular Ca2+ concentrations associated with Phe‐induced pressor responses were increased in the mesenteric arteries of the HS offspring. PKC α‐ and δ‐isoforms were upregulated in mesenteric arteries of the HS offspring. The enhanced Phe‐mediated vascular activity was linked to the altered PKC‐modulated BK channel functions.ConclusionThe results suggested that prenatal exposure to HS altered microvascular activity probably via changes in PKC/BK signaling pathways, which may lead to increased risks of hypertension in the offspring.
Glabridin, an isoflavan from licorice root, downregulates iNOS expression and activity under high‐glucose stress and inflammation
Authors: Yehuda Itamar , Madar Zecharia , Leikin‐Frenkel Alicia , Tamir Snait 
Published: March 2015

ScopeIn females, hyperglycemia abolishes estrogen‐vascular protection, leading to inflammation and oxidative stress that are related to diabetes‐associated cardiovascular complications. Such knowledge led us to examine the potential of glabridin, as a replacement of estrogen anti‐inflammatory activity under high‐glucose conditions.Methods and resultsIn macrophage‐like cells, chronic glucose stress (28 and 44 mM) upregulated inducible nitric oxide synthase (iNOS) mRNA expression by 42 and 189%, respectively. Pretreatment with glabridin, under chronic glucose stress, downregulated the LPS‐induced nitric oxide secretion and nitrotyrosine formation, by 39 and 21%, respectively. Pretreatment with estradiol did not prevent the LPS‐induced nitrotyrosine formation. Furthermore, glabridin, brought about a decrease in the LPS‐induced iNOS mRNA expression by 48%, as compared to cells pretreated with estradiol. Glabridin decreased protein levels of liver iNOS by 69% in adult mouse offspring which developed hyperglycemia after early fetal exposure to a saturated fatty acid‐enriched maternal diet. Glabridin also decreased liver nitrotyrosine levels in offspring of regular diet‐fed mothers after further receiving high‐fat diet.ConclusionSuch results indicate that glabridin retains anti‐inflammatory abilities to regulate the synthesis and activity of iNOS under high‐glucose levels, implying that a glabridin supplement may serve as an anti‐inflammatory agent in diabetes‐related vascular dysfunction.
Resolving relaxometry and diffusion properties within the same voxel in the presence of crossing fibres by combining inversion recovery and diffusion‐weighted acquisitions
Authors: De Santis Silvia , Barazany Daniel , Jones Derek K. , Assaf Yaniv 
Published: March 2015

PurposeA comprehensive image‐based characterization of white matter should include the ability to quantify myelin and axonal attributes irrespective of the complexity of fibre organization within the voxel. While progress has been made with diffusion MRI‐based approaches to measure axonal morphology, to date available myelin metrics simply assign a single scalar value to the voxel, reflecting some form of average of its constituent fibres. Here, a new experimental framework that combines diffusion MRI and relaxometry is introduced. It provides, for the first time, the ability to assign to each unique fibre system within a voxel, a unique value of the longitudinal relaxation time, T1, which is largely influenced by the myelin content.MethodsWe demonstrate the method through simulations, in a crossing fibres phantom, in fixed brains and in vivo.ResultsThe method is capable of recovering unique values of T1 for each fibre population.ConclusionThe ability to extract fibre‐specific relaxometry properties will provide enhanced specificity and, therefore, sensitivity to differences in white matter architecture, which will be invaluable in many neuroimaging studies. Further the enhanced specificity should ultimately lead to earlier diagnosis and access to treatment in a range of white matter diseases where axons are affected. Magn Reson Med 75:372–380, 2016. © 2015 The Authors. Magnetic Resonance in Medicine Published by Wiley Periodicals, Inc. on behalf of International Society of Medicine in Resonance.
Flexor carpi radialis surface electromyography electrode placement for evoked and voluntary measures
Authors: Green Lara A. , McGuire Jessica , Gabriel David A. 
Published: March 2015

ABSTRACTIntroduction: In this study we evaluated the reliability of bipolar electrode recordings, which allow for undistorted compound muscle action potentials (CMAPs) while minimizing cross‐talk during voluntary contractions. Methods: Twenty‐four men completed maximal voluntary wrist flexion contractions in 4 test sessions. Compound muscle action potentials were also evoked during each session. Surface electromyography was recorded from the flexor carpi radialis (FCR) with the recording electrode (G1) placed on the motor point and a second recording electrode (G2) adjacent to G1. Reliability was assessed using intraclass correlational analysis of variance and standard error of measurement. Results: Root‐mean‐square (RMS) amplitude and mean power frequency (MPF) were highly reliable (R = 0.89 and 0.84, respectively). The CMAPs also exhibited good reliability (R = 0.75). Normalization of RMS amplitude reduced the intraclass reliability coefficient (R = 0.85). Conclusion: The electrode placement resulted in reliable measures from voluntary contractions and CMAPs. Normalization can decrease reliability. Muscle Nerve 52: 818–825, 2015