bluuebunny/crossref_metadata_2025 huggingface dataset:
Jak psát kvalitativně orientované výzkumné studie. Kvalita v kvalitativním výzkumu
Authors: Šeďová K. , Švaříček R.
Published: October 2013

Cílem této metodologické studie je definovat základní pravidla dobré kvalitativně orientované empirické studie, to znamená výzkumné zprávy prezentující výsledky kvalitativního výzkumného šetření, která je určena k publikaci v odborném vědeckém časopise. Sdílíme přitom odstup vůči jednoznačně formulovaným kritériím kvality kvalitativního výzkumu, která mohou omezovat autonomii výzkumníka v rozhodování o vlastních postupech. Naše pravidla je proto třeba vnímat jako rámcová doporučení, která umožní autorovi udržet kontrolu nad kvalitou vlastního výzkumu. Uváděná pravidla se vztahují ke čtyřem klíčovým oblastem výzkumné zprávy: věnujeme se (1) teoretickému rámci studie, (2) popisu plánu a průběhu výzkumu, (3) výstupům z analýzy a interpretaci dat a (4) jazyku a stylu psaní výzkumné zprávy. Postupně definujeme 16 základních pravidel kvalitativního psaní, která vykládáme za pomoci metodologické literatury a komentovaných příkladů z publikovaných i nepublikovaných kvalitativních studií. Domníváme se, že uvedená pravidla lze doporučit začínajícím autorům odborných vědeckých textů určených pro recenzované pedagogické časopisy jako základní vodítka.
Confirmation of secondary cosmic ray flux enhancement during the total lunar eclipse of 10 December 2011
Authors: Raghav Anil , Bhaskar Ankush , Yadav Virendra , Bijewar Nitinkumar , Pai Chintamani , Koli Ashish , Navale Nilam , Singh Gurinderpal , Dubey Nitin , Pawar Sushant , Parab Pradnya , Narvankar Gandhali , Rawoot Vaibhav , Rawat Vikas , Borse Satish , Garad Nagnath , Rozario Carl , Kaushal Nitin , Tiwari Shailendrakumar , Press M. R.
Published: October 2013

Temporal variation of secondary cosmic rays (SCR) flux was measured during the total lunar eclipse on 10 December 2011 and the subsequent full moon on 8 January 2012 from Mumbai (Geomagnetic latitude: 10.6°N), India. The measurements were done by using NaI (Tl) scintillation detector with energy threshold of 200 keV. The SCR flux shows approximately 8.1% enhancement during the lunar eclipse as compared to the average of pre‐ and post‐eclipse periods. Weather parameters (temperature and relative humidity) were continuously monitored, and their correlations with temporal variation in SCR flux have been examined. The influences of geomagnetic field, interplanetary parameters, and tidal effect on SCR flux have been considered. Qualitative analysis of SCR flux variation indicates that local weather, interplanetary, and geomagnetic factors affecting SCR flux fail to explain the observed enhancement during the eclipse. Lunar tidal effect on magnetosphere and crust still remains a possible mechanism which needs to be investigated in detail. The enhancement during lunar eclipse and widely reported decrease during solar eclipses may unravel hitherto unnoticed factors modulating SCR flux.
Organic Junction Field‐Effect Transistor
Authors: Lüssem Björn , Kleemann Hans , Kasemann Daniel , Ventsch Fabian , Leo Karl
Published: October 2013

The realization and performance of a novel organic field‐effect transistor—the organic junction field‐effect transistor (JFET)—is discussed. The transistors are based on the modulation of the thickness of a depletion layer in an organic pin junction with varying gate potential. Based on numerical modeling, suitable layer thicknesses and doping concentrations are identified. Experimentally, organic JFETs are realized and it is shown that the devices clearly exhibit amplification. Changes in the electrical characteristics due to a variation of the intrinsic and the p‐doped layer thickness are rationalized by the numerical model, giving further proof to the proposed operational mechanism.
Synthesis of hyperbranched polymethylvinylborosiloxanes and modification of addition‐curable silicone with improved thermal stability
Authors: Li Lizhi , Zhao Jingbo , Li Hao , Zhao Tong
Published: October 2013

This paper reports a non‐catalyzed environmentally friendly method of synthesizing hyperbranched polymethylvinylborosiloxanes (PMVBSs) and their use to improve the thermal stability of normal addition‐curable silicones (ACSs). PMVBSs were synthesized by the direct polycondensation of dimethoxymethylvinylsilane with boric acid at 80–130°C in 1,4‐dioxane or diglyme. They were characterized by gel permeation chromatography; FT‐IR; 1H, 13C, 29Si and 11B NMR; and TGA. PMVBSs were composed of Si―O―Si and Si―O―B bridges with some unreacted B―OH groups remaining, and had a ceramic yield up to 65.97% at 900°C. PMVBS‐modified ACSs (PBS‐ACSs) were prepared by curing the PMVBSs with hydrogen‐containing silicone oil under Karstedt (platinum divinyltetramethyldisiloxane) catalysis. Thermal stability of PBS‐ACSs was characterized by TGA in N2 or air, and ceramic yields as high as 76.7% were obtained. Gas decomposition during the ceramization of PBS‐ACSs was examined by TG/mass spectroscopy. The SiBOC ceramics formed were characterized by FT‐IR, Raman, 29Si and 11B magic angle spinning NMR and elemental analysis. This method provides a valuable way to improve the thermal stability of ACSs. Copyright © 2013 John Wiley & Sons, Ltd.
The Incidence and Prevalence of Systemic Lupus Erythematosus, 2002–2004: The Georgia Lupus Registry
Authors: Lim S. Sam , Bayakly A. Rana , Helmick Charles G. , Gordon Caroline , Easley Kirk A. , Drenkard Cristina
Published: October 2013

Objective

The Georgia Lupus Registry is a population‐based registry designed to improve our ability to estimate the incidence and prevalence of systemic lupus erythematosus (SLE) in a large population.

Methods

Potential cases of SLE were identified from multiple sources during the years 2002 through 2004. Cases were defined according to the American College of Rheumatology (ACR) criteria for SLE or a combined definition. Age‐standardized rates were determined and stratified by race and sex. With capture–recapture analyses, we estimated the underascertainment of cases.

Results

Using the ACR case definition, the overall crude and age‐adjusted incidence rate was 5.6 per 100,000, with capture–recapture and combined definition rates being slightly higher. The age‐adjusted incidence rate in women was >5 times higher than that for men (9.2 versus 1.8). Black women had an incidence rate nearly 3 times higher than that in white women, with a significantly higher rate in the group ages 30–59 years. The overall crude and age‐adjusted prevalence rates were 74.4 and 73 per 100,000, respectively. The age‐adjusted prevalence rate in women was nearly 9 times higher than that for men (127.6 versus 14.7). Black women had very high rates (196.2). A striking difference was seen in the proportion of prevalent cases with end‐stage renal disease, with 7‐fold greater involvement among black patients.

Conclusion

With the more complete case‐finding methods we used, the incidence and prevalence rates of SLE are among the highest reported in the US. The results continue to underscore striking sex, age, and racial disparities between black patients and white patients with SLE.
A comparison of convergently evolved insect silks that share β‐sheet molecular structure
Authors: Church Jeffrey S. , Woodhead Andrea L. , Walker Andrew A. , Sutherland Tara D.
Published: October 2013

Raspy crickets produce silk webs that are used to build shelters. These webs have been found to consist of both fiber and film components. Raman spectra obtained from both components were found to be very similar for a given species. The protein structure of the fibers and films produced by both species was predominately β‐sheet with lesser amounts of β‐turns, unordered and α‐helical protein also detected. The orientation of the β‐sheet backbone in the fiber was determined to be parallel to the fiber axis. Compared to cocoon and dragline silk the orientation distribution exhibits a significant randomly orientated protein component. Amino acid analysis confirmed the presence of glycine, serine, and alanine in both species, which are known to form antiparallel β‐sheet structures. Both species, although at significantly different concentrations, where found to contain proline. This amino acid is uncommon in insect silks, and likely involved in increasing fiber elasticity. © 2013 Wiley Periodicals, Inc. Biopolymers 101: 630–639, 2014.
A defined co‐culture of Geobacter sulfurreducens and Escherichia coli in a membrane‐less microbial fuel cell
Authors: Bourdakos Nicholas , Marsili Enrico , Mahadevan Radhakrishnan
Published: October 2013

Wastewater‐fed microbial fuel cells (MFCs) are a promising technology to treat low‐organic carbon wastewater and recover part of the chemical energy in wastewater as electrical power. However, the interactions between electrochemically active and fermentative microorganisms cannot be easily studied in wastewater‐fed MFCs because of their complex microbial communities. Defined co‐culture MFCs provide a detailed understanding of such interactions. In this study, we characterize the extracellular metabolites in laboratory‐scale membrane‐less MFCs inoculated with Geobacter sulfurreducens and Escherichia coli co‐culture and compare them with pure culture MFCs. G. sulfurreducens MFCs are sparged to maintain anaerobic conditions, while co‐culture MFCs rely on E. coli for oxygen removal. G. sulfurreducens MFCs have a power output of 128 mW m−2, compared to 63 mW m−2 from the co‐culture MFCs. Analysis of metabolites shows that succinate production in co‐culture MFCs decreases current production by G. sulfurreducens and that the removal of succinate is responsible for the increased current density in the late co‐culture MFCs. Interestingly, pH adjustment is not required for co‐culture MFCs but a base addition is necessary for E. coli MFCs and cultures in vials. Our results show that defined co‐culture MFCs provide clear insights into metabolic interactions among bacteria while maintaining a low operational complexity. Biotechnol. Bioeng. 2014;111: 709–718. © 2013 Wiley Periodicals, Inc.
Mechanisms of inhibition of endothelial cell migration by taxanes
Authors: Kamath Kathy , Smiyun Greg , Wilson Leslie , Jordan Mary Ann
Published: October 2013

Several antiangiogenic mechanisms have been proposed for the widely‐used cancer chemotherapeutic drugs taxotere (docetaxel) and taxol (paclitaxel), but none has been definitively identified. We analyzed their effects at a range of concentrations on migration and mitosis of human umbilical vein endothelial cells (HUVECs) on microtubule and focal adhesion morphology and microtubule dynamic instability during migration. Both taxanes inhibited migration by inhibiting both maintenance of the forward direction of the cell and by slowing migration over the entire contorted path length. At low (but not all) taxane concentrations that inhibit HUVEC migration, the shortening rates and shortening lengths of microtubules at the leading edge were strongly inhibited; peripheral microtubules were reduced in number and fewer targeted focal adhesions; focal adhesions doubled in length and became ring‐shaped, elongate, and reduced in number; and an increase in stabilized microtubules occurred centrally. HUVEC migration was 13–19‐fold more sensitive to taxanes than was mitosis confirming that taxanes exhibit significant effects in addition to mitotic arrest that may contribute to their overall antitumor effects. No relationship was detected between centrosome position and migration characteristics. The data suggest that taxanes inhibit migration, at least in part, by inhibiting the dynamic instability of microtubules that possibly interact with guanine nucleotide exchange factors and thus with the focal adhesion–associated G‐proteins that then lead to disruption of the regulated formation and turnover of focal adhesions. A mechanism is presented by which subcytotoxic concentrations of taxanes might stabilize dynamic instability of a few microtubules and thereby inhibit migration and angiogenesis. © 2013 Wiley Periodicals, Inc.
CloudMon: a resource‐efficient IaaS cloud monitoring system based on networked intrusion detection system virtual appliances
Authors: Li Bo , Li Jianxin , Liu Lu
Published: October 2013

The networked intrusion detection system virtual appliance (NIDS‐VA), also known as virtualized NIDS, plays an important role in the protection and safeguard of IaaS cloud environments. However, it is nontrivial to guarantee both of the performance of NIDS‐VA and the resource efficiency of cloud applications because both are sharing computing resources in the same cloud environment. To overcome this challenge and trade‐off, we propose a novel system, named CloudMon, which enables dynamic resource provision and live placement for NIDS‐VAs in IaaS cloud environments. CloudMon provides two techniques to maintain high resource efficiency of IaaS cloud environments without degrading the performance of NIDS‐VAs and other virtual machines (VMs). The first technique is a virtual machine monitor based resource provision mechanism, which can minimize the resource usage of a NIDS‐VA with given performance guarantee. It uses a fuzzy model to characterize the complex relationship between performance and resource demands of a NIDS‐VA and develops an online fuzzy controller to adaptively control the resource allocation for NIDS‐VAs under varying network traffic. The second one is a global resource scheduling approach for optimizing the resource efficiency of the entire cloud environments. It leverages VM migration to dynamically place NIDS‐VAs and VMs. An online VM mapping algorithm is designed to maximize the resource utilization of the entire cloud environment. Our virtual machine monitor based resource provision mechanism has been evaluated by conducting comprehensive experiments based on Xen hypervisor and Snort NIDS in a real cloud environment. The results show that the proposed mechanism can allocate resources for a NIDS‐VA on demand while still satisfying its performance requirements. We also verify the effectiveness of our global resource scheduling approach by comparing it with two classic vector packing algorithms, and the results show that our approach improved the resource utilization of cloud environments and reduced the number of in‐use NIDS‐VAs and physical hosts. Copyright © 2013 John Wiley & Sons, Ltd.
Distinct genetic requirements for BX‐C‐mediated specification of abdominal denticles
Authors: Sambrani Nagraj , Pradel Jacques , Graba Yacine
Published: October 2013

Background: Hox genes encode transcription factors playing important role in segment specific morphogenesis along the anterior posterior axis. Most work in the Hox field aimed at understanding the basis for specialised Hox functions, while little attention was given to Hox common function. In Drosophila, genes of the Bithorax complex [Ultrabithorax (Ubx), abdominalA (abdA), and AbdominalB (AbdB)] all promote abdominal identity. While Ubx and AbdA share extensive sequence conservation, AbdB is highly divergent, questioning how it can perform similar functions as Ubx and AbdA. Results: In this study, we investigate the genetic requirement for the specification of abdominal‐type denticles by Ubx, AbdA, and AbdB. The impact of ectopic expression of Hox proteins in embryos mutant for Exd as well as of Wingless or Hedgehog signaling involved in intrasegmental patterning was analyzed. Results indicated that Ubx and AbdA do not require Exd, Wg, and Hh activity for specifying abdominal‐type denticles, while AbdB does. Conclusions: Our results support that distinct regulatory mechanisms underlie Ubx/AbdA‐ and AbdB‐mediated specification of abdominal‐type denticles, highlighting distinct strategies for achieving a similar biological output. This suggests that common function performed by distinct paralogue Hox proteins may also rely on newly acquired property, instead of conserved/ancestral properties. Developmental Dynamics 243:192–200, 2014. © 2013 Wiley Periodicals, Inc.
UV radiation is the primary factor driving the variation in leaf phenolics across Chinese grasslands
Authors: Chen Litong , Niu Kechang , Wu Yi , Geng Yan , Mi Zhaorong , Flynn Dan F.B. , He Jin‐Sheng
Published: October 2013

Due to the role leaf phenolics in defending against ultraviolet B (UVB) under previously controlled conditions, we hypothesize that ultraviolet radiation (UVR) could be a primary factor driving the variation in leaf phenolics in plants over a large geographic scale. We measured leaf total phenolics, ultraviolet‐absorbing compounds (UVAC), and corresponding leaf N, P, and specific leaf area (SLA) in 151 common species. These species were from 84 sites across the Tibetan Plateau and Inner Mongolian grasslands of China with contrasting UVR (354 vs. 161 mW/cm2 on average). Overall, leaf phenolics and UVAC were all significantly higher on the Tibetan Plateau than in the Inner Mongolian grasslands, independent of phylogenetic relationships between species. Regression analyses showed that the variation in leaf phenolics was strongly affected by climatic factors, particularly UVR, and soil attributes across all sites. Structural equation modeling (SEM) identified the primary role of UVR in determining leaf phenolic concentrations, after accounting for colinearities with altitude, climatic, and edaphic factors. In addition, phenolics correlated positively with UVAC and SLA, and negatively with leaf N and N: P. These relationships were steeper in the lower‐elevation Inner Mongolian than on the Tibetan Plateau grasslands. Our data support that the variation in leaf phenolics is controlled mainly by UV radiation, implying high leaf phenolics facilitates the adaptation of plants to strong irradiation via its UV‐screening and/or antioxidation functions, particularly on the Tibetan Plateau. Importantly, our results also suggest that leaf phenolics may influence on vegetation attributes and indirectly affect ecosystem processes by covarying with leaf functional traits.
Synthesis of Planar Metal Complexes and the Stacking Abilities of Naphthalenediol‐Based Acyclic and Macrocyclic Salen‐Type Ligands
Authors: Akine Shigehisa , Varadi Zoltan , Nabeshima Tatsuya
Published: October 2013

A salen‐type ligand, H4L1, having two 1,8‐naphthalenediol moieties, was designed and synthesized to obtain planar metal complexes in which the naphthalene π surface was expected to increase the stacking ability. Spectroscopic and crystallographic investigations revealed that the uncomplexed H4L1ligand existed exclusively in the keto/keto form and adopted a nonplanar structure. Upon complexation with divalent metal sources M (Ni, Cu, Zn, Pd), the H4L1ligand gave the corresponding mononuclear complexes [H2L1M] (M = Ni, Cu, Pd) or [H2L1Zn(dmso)], in which the metal ion occupies the salen‐type N2O2coordination site. In particular, [H2L1Ni] and [H2L1Pd] adopted a highly planar structure, allowing the formation of well‐organized stacking structures in the crystalline state as well as self‐association in solution. The corresponding macrocyclic ligand, H4L2, was also designed to obtain a more organized stacking structure due to the higher π surface area. Although the [2+2] macrocyclization without a template did not efficiently give the ligand H4L2, the metal‐templates of Ni2+and Cu2+significantly increased the [2+2] macrocyclization efficiency to produce the dinuclear [L2Ni2] and [L2Cu2] species. The [L2Ni2] molecule had a highly planar structure incorporating two nickel(II) ions in an almost ideal square‐planar geometry. In the crystalline state, the [L2Ni2] molecules formed a parallel stacking structure with a brick‐wall arrangement. The central O4site of the [L2Ni2] complex was found to be capable of binding a third metal ion such as Ni2+, Cu2+or Zn2+.
Linker Effects on Amino Acid and Peptide Recognition by Molecular Tweezers
Authors: Dutt Som , Wilch Constanze , Gersthagen Thomas , Wölper Christoph , Sowislok Andrea Anna , Klärner Frank‐Gerrit , Schrader Thomas
Published: October 2013

Transition from monotopic symmetrical to ditopic unsymmetrical molecular recognition frequently occurs when a general, powerful, but unspecific receptor molecule is transformed into a specific ditopic host. Especially in water, this endeavor is accompanied by great challenges, comprising, among other things, host–guest orientation, orthogonal recognition modes, and the nature of the linker unit. This work presents a case study on a powerful general host for basic amino acids and peptides. The symmetrical molecular tweezer skeleton was systematically desymmetrized and modified with various common linker units, and the profound influence of these changes on the molecular recognition profile was studied in detail by NMR spectroscopy, fluorescence titrations, X‐ray crystallography, and molecular simulations. A number of diverse effects were revealed that could be attributed to the chemical nature of the different linkers. In general, long alkyl tethers block the cavity of the tweezers by van der Waals contacts to CH groups around its entrance; alkoxyalkyl tethers likewise lower tweezer affinities for basic amino acids by competing self‐inclusion. As a general trend, affinities for linkers with ester and carboxylate moieties were substantially higher than those for tethers with ethers and alcohols, likely because the electron‐rich carbonyl group keeps the cavity open. Additional hydrogen bonds between the linker unit and suitable amino acid or peptide guests greatly support the complexation process; finally, high solvent polarity and salt load shift the binding equilibrium from external ion pairing to guest inclusion.
Helicobacter pylori antibody responses and evolution of precancerous gastric lesions in a Chinese population
Authors: Pan Kai‐Feng , Formichella Luca , Zhang Lian , Zhang Yang , Ma Jun‐Ling , Li Zhe‐Xuan , Liu Cong , Wang Yu‐Mei , Goettner Gereon , Ulm Kurt , Classen Meinhard , You Wei‐Cheng , Gerhard Markus
Published: October 2013

Helicobacter pylori‐specific proteins are involved in gastric carcinogenesis. To investigate the seroprevalence of six H. pylori‐specific antibodies in patients with different gastric histology, and the impact of seropositivities on the evolution of precancerous gastric lesions, a follow‐up study was conducted in Linqu County, China. The seropositivities for CagA, VacA, GroEL, UreA, HcpC and gGT were assessed by recomLine analysis in 573 H. pylori‐positive subjects and correlated with evolution of precancerous gastric lesions. We found that the score of H. pylori recomLine test was significantly increased in subjects with chronic atrophic gastritis (CAG, p < 0.0001) or intestinal metaplasia (IM, p = 0.0125), and CagA was an independent predictor of advanced gastric lesions, adjusted odds ratios (ORs) were 2.54 (95% CI = 1.42–4.55) for IM and 2.38 (95% CI = 1.05–5.37) for dysplasia (DYS). Moreover, seropositivities for CagA and GroEL were identified as independent predictors for progression of gastric lesions in a longitudinal study, and ORs were 2.89 (95% CI = 1.27–6.59) and 2.20 (95% CI = 1.33–3.64), respectively. Furthermore, the risk of progression was more pronounced in subjects with more than three positive antigens (pfor trend = 0.0003). This population‐based study revealed that seropositivities for CagA and GroEL might be potential markers to identify patients infected with high‐risk H. pylori strains, which are related to the development of GC in a Chinese high‐risk population, and recomLine test might serve as a tool for risk stratification.
Distribution of molecules locally delivered from bone cement
Authors: Giers Morgan B. , McLaren Alex C. , Schmidt Kenneth J. , Caplan Michael R. , McLemore Ryan
Published: October 2013

Revision of infected orthopedic implants is successful in most cases when antimicrobials are delivered locally (mixed with bone cement or bone graft which is placed in the site from which the infected tissue was removed); however, there is still a substantial rate of recurrence most likely due to the antimicrobials not achieving a therapeutic dose at all locations in the tissue. To study transport within this environment, gadolinium chelated in diethylene triamine pentaacetic acid (Gd‐DTPA), a MRI contrast agent with size and solubility similar to two common antimicrobials (gentamicin and vancomycin), was mixed with bone cement, implanted in vivo into two models of orthopedic surgical wounds, and imaged using MRI 5.5 h after implantation. Image thresholding was used to create two‐dimensional and three‐dimensional representations of areas/volumes containing detectable concentrations of Gd‐DTPA. Distribution is found to be anisotropic with Gd‐DTPA transporting preferentially anterior of the implant toward the skin. When fascia is not closed over the implant site, Gd‐DTPA transports to the skin and along the subcutaneous plane. The distance transported indicates that transport is likely driven by convection. Finally, the tissue concentration of Gd‐DTPA is much less than the concentration loaded into the bone cement. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 102B: 806–814, 2014.
Differentiation of calcified regions and iron deposits in the ageing brain on conventional structural MR images
Authors: del C. Valdés Hernández Maria , Glatz Andreas , Kiker Alexander J. , Dickie David Alexander , Aribisala Benjamin S. , Royle Natalie A. , Muñoz Maniega Susana , Bastin Mark E. , Deary Ian J. , Wardlaw Joanna M.
Published: October 2013

Purpose

In the human brain, minerals such as iron and calcium accumulate increasingly with age. They typically appear hypointense on T2*‐weighted MRI sequences. This study aims to explore the differentiation and association between calcified regions and noncalcified iron deposits on clinical brain MRI in elderly, otherwise healthy subjects.

Materials and Methods

Mineral deposits were segmented on co‐registered T1‐ and T2*‐weighted sequences from 100 1.5 Tesla MRI datasets of community‐dwelling individuals in their 70s. To differentiate calcified regions from noncalcified iron deposits we developed a method based on their appearance on T1‐weighted images, which was validated with a purpose‐designed phantom. Joint T1‐ and T2*‐weighted intensity histograms were constructed to measure the similarity between the calcified and noncalcified iron deposits using a Euclidean distance based metric.

Results

We found distinct distributions for calcified regions and noncalcified iron deposits in the cumulative joint T1‐ and T2*‐weighted intensity histograms across all subjects (correlations ranging from 0.02 to 0.86; mean = 0.26 ± 0.16; t = 16.93; P < 0.001) consistent with differences in iron and calcium signal in the phantom. The mean volumes of affected tissue per subject for calcified and noncalcified deposits were 236.74 ± 309.70 mm3 and 283.76 ± 581.51 mm3; respectively. There was a positive association between the mineral depositions (β = 0.32, P < 0.005), consistent with existing literature reports.

Conclusion

Calcified mineral deposits and noncalcified iron deposits can be distinguished from each other by signal intensity changes on conventional 1.5T T1‐weighted MRI and are significantly associated in brains of elderly, otherwise healthy subjects. J. Magn. Reson. Imaging 2014;40:324–333 © 2013 Wiley Periodicals, Inc.
MR diffusion tensor imaging of normal kidneys
Authors: Wang Wen‐juan , Pui Margaret H. , Guo Yan , Hu Xiao‐shu , Wang Huan‐jun , Yang Dong
Published: October 2013

Purpose

To assess the feasibility of diffusion tensor imaging (DTI) of normal kidneys and the influence of hydration state.

Materials and Methods

Ten healthy volunteers underwent renal DTI after fasting for 12 hours and 4 hours, without fasting, and following water diuresis. Medullary and cortical apparent diffusion coefficient (ADC) and fractional anisotropy (FA) values were measured and compared in the four different states of hydration. DTI was performed with a 3T magnetic resonance imaging (MRI) system using fat‐saturated single‐shot spin‐echo echo planar imaging sequence.

Results

ADC of normal cortex (2.387 ± 0.081 × 10−3 mm2/s) was significantly higher (t = 20.126, P = 0) than that of medulla (1.990 ± 0.063 × 10−3 mm2/s). The FA value of normal cortex (0.282 ± 0.017) was significantly lower (t = −42.713, P = 0) than that of medulla (0.447 ± 0.022). The ADC and FA values of the left renal cortex (2.404 ± 0.082 × 10−3 mm2/s, 0.282 ± 0.017) and medulla (2.002 ± 0.081 × 10−3 mm2/s, 0.452 ± 0.024) were not significantly different (P > 0.05) from those of right renal cortex (2.369 ± 0.080 × 10−3 mm2/s, 0.283 ± 0.018) and medulla (1.978 ± 0.039 × 10−3 mm2/s, 0.443 ± 0.019). Values for ADC (×10−3mm2/s) and FA in the 12‐hour fasting, 4‐hour fasting, nonfasting, and water diuresis states were 2.372 ± 0.095 and 0.278 ± 0.018, 2.387 ± 0.081 and 0.282 ± 0.017, 2.416 ± 0.051 and 0.279 ± 0.023, 2.421 ± 0.068, and 0.270 ± 0.021, respectively, in cortex, 1.972 ± 0.084 and 0.438 ± 0.014, 1.990 ± 0.063 and 0.447 ± 0.022, 2.021 ± 0.081 and 0.450 ± 0.031, 2.016 ± 0.076 and 0.449 ± 0.028, respectively, in medulla. The ADC and FA values in different hydration states were not significantly different (P > 0.05).

Conclusion

DTI of normal kidneys is feasible with reproducible ADC and FA values independent of hydration states. J. Magn. Reson. Imaging 2014;40:1099–1102. © 2013 Wiley Periodicals, Inc.
PTEN regulates matrix synthesis in adult human chondrocytes under oxidative stress
Authors: Iwasa Kenjiro , Hayashi Shinya , Fujishiro Takaaki , Kanzaki Noriyuki , Hashimoto Shingo , Sakata Shuhei , Chinzei Nobuaki , Nishiyama Takayuki , Kuroda Ryosuke , Kurosaka Masahiro
Published: October 2013

Phosphatase and tensin homologue deleted on chromosome 10 (PTEN) was identified as an important tumor suppressor gene. PTEN functions as a negative regulator of phosphoinositol‐3‐kinase (PI3K)‐Akt and MEK/ERK signaling. The PI3K‐Akt pathway is critical for cell survival, differentiation, and matrix synthesis. Oxidative stress is considered a critical factor in the onset and progression of osteoarthritis (OA). Therefore, we investigated the function of PTEN in OA chondrocytes under oxidative stress. Chondrocytes were treated with insulin‐like growth factor‐1 (IGF‐1) and/or tert‐butyl hydroperoxide (tBHP), which causes oxidative stress. The expression levels of type2 collagen (Col2a1) and aggrecan were analyzed by real‐time PCR, and phosphorylation of Akt and ERK1/2 was analyzed by Western blotting. Chondrocytes were treated with PTEN‐specific small interfering RNA (siRNA), as well as IGF‐1 and/or tBHP. PTEN and IGF‐1 expressions in OA chondrocytes were increased. The downregulation of PTEN expression increased the expression levels of Col2a1 and aggrecan, and increased proteoglycan synthesis under oxidative stress. Oxidative stress decreased the phosphorylation of Akt and increased that of ERK1/2. The downregulation of PTEN expression increased Akt phosphorylation, but did not increase that of ERK 1/2. Our results suggest that PTEN regulates matrix synthesis via the PI3K‐Akt pathway under oxidative stress. © 2013 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 32:231–237, 2014.
Drug‐induced sleep endoscopy in sleep‐disordered breathing: Report on 1,249 cases
Authors: Vroegop Anneclaire V. , Vanderveken Olivier M. , Boudewyns An N. , Scholman Joost , Saldien Vera , Wouters Kristien , Braem Marc J. , Van de Heyning Paul H. , Hamans Evert
Published: October 2013

Objectives/Hypothesis

To describe upper airway (UA) collapse patterns during drug‐induced sleep endoscopy (DISE) in a large cohort of patients with sleep‐disordered breathing (SDB) and to assess associations with anthropometric and polysomnographic parameters.

Study Design

Observational study.

Methods

A total of 1,249 patients [age 47 ± 10 y; apnea–hypopnea index (AHI) 18.9 ± 15.3/h; body mass index (BMI) 27.2 ± 3.7 kg/m2] underwent polysomnography and DISE. DISE findings were categorized to the following UA levels: palate, oropharynx, tongue base, and hypopharynx. The degree of collapse was reported as complete, partial, or none. The pattern of the obstruction was described as anteroposterior, lateral, or concentric. Associations between DISE findings and anthropometric and polysomnographic parameters were analyzed.

Results

Palatal collapse was seen most frequently (81%). Multilevel collapse was noted in 68.2% of all patients. The most frequently observed multilevel collapse pattern was a combination of palatal and tongue base collapse (25.5%). Palatal collapse was seen most frequently (81%). The prevalence of complete collapse, multilevel collapse, and hypopharyngeal collapse increased with increasing severity of obstructive sleep apnea (OSA). Multilevel and complete collapse were more prevalent in obese patients and in those with more severe OSA. Both higher BMI and AHI values were associated with a higher probability of complete concentric palatal collapse.

Conclusion

The current study provides an overview of UA collapse patterns in a large cohort of SDB patients who underwent DISE. The associations found in this study may indicate that UA collapse patterns observed during DISE cannot be fully explained by selected baseline polysomnographic and anthropometric characteristics.

Level of Evidence

4. Laryngoscope, 124:797–802, 2014
Voice in female‐to‐male transsexual persons after long‐term androgen therapy
Authors: Cosyns Marjan , Van Borsel John , Wierckx Katrien , Dedecker David , Van de Peer Fleur , Daelman Tine , Laenen Sofie , T'Sjoen Guy
Published: October 2013

Objectives/Hypothesis

The aim of the present study was to 1) document voice in a large sample of female‐to‐male transsexual persons (FMT), 2) compare their vocal characteristics with those of heterosexual biological males, and 3) determine hormonal factors with impact on their fundamental frequency.

Study Design

This was a controlled cross‐sectional study. It is the largest study to date on voice and voice change in FMT, and the first to include a control group and FMT who were under long‐term androgen administration.

Methods

Thirty‐eight FMT, ranging in age between 22 and 54 years, and 38 controls, frequency matched by age and smoking behavior, underwent a voice assessment that comprised the determination of pitch, intonation, and perturbation parameters measured during sustained vowel production, counting, and reading. Hormonal factors explored were hematocrit, total testosterone level, luteinizing hormone level, and biallelic mean length of the cytosine‐adenine‐guanine (CAG) trinucleotide repeat sequence in the androgen receptor gene.

Results

It was found that the FMT as a group did not differ significantly from controls for any of the acoustic voice variables studied. However, in about 10% pitch lowering was not totally unproblematic. The lowest‐pitched (i.e., more male) voices were observed in FMT with higher hematocrit and longer CAG repeats.

Conclusion

After long‐term androgen therapy, FMT generally demonstrate an acceptable male voice. Pitch‐lowering difficulties can be expected in about 10% of cases and appear, at least in part, to be associated with diminished androgen sensitivity.

Level of Evidence

3b. Laryngoscope, 124:1409–1414, 2014
Small RNA regulation of reproductive function
Authors: Hale Benjamin J. , Yang Cai‐Xia , Ross Jason W.
Published: October 2013

Post‐transcriptional gene regulation is one mechanism that occurs “above the genome,” allowing the cells of an organism to have dramatically different phenotypes and functions. Non‐coding ribonucleic acid (ncRNA) molecules regulate transcript and protein abundance above the level of transcription, and appear to play substantial roles in regulation of reproductive tissues. Three primary classes of small ncRNA are microRNA (miRNA), endogenous small interfering RNA (endo‐siRNA), and PIWI‐interacting RNA (piRNA). These RNA classes have similarities and clear distinctions between their biogenesis and in the interacting protein machinery that facilitate their effects on cellular phenotype. Characterization of the expression and importance of the critical components for the biogenesis of each class in different tissues is continuously contributing a better understanding of each of these RNA classes in different reproductive cell types. Here, we discuss the expression and potential roles of miRNA, endo‐siRNA, and piRNA in reproduction from germ‐cell development to pregnancy establishment and placental function. Additionally, the potential contribution of RNA binding proteins, long ncRNAs, and the more recently discovered circular RNAs (circRNAs) in relation to small RNA function is discussed. Mol. Reprod. Dev. 81: 148–159, 2014. © 2013 Wiley Periodicals, Inc.
Muscle shear modulus measured with ultrasound shear‐wave elastography across a wide range of contraction intensity
Authors: Yoshitake Yasuhide , Takai Yohei , Kanehisa Hiroaki , Shinohara Minoru
Published: October 2013

Introduction: In this study we examine the repeatability of measuring muscle shear modulus using ultrasound shear‐wave elastography between trials and between days, and the association between shear modulus and contraction intensity over a wide range of intensities. Methods: Shear modulus of the biceps brachii was determined using ultrasound shear‐wave elastography during static elbow flexion (up to 60% of maximal contraction) in healthy young adults. Results: The correspondence of shear modulus was confirmed in phantoms between the manufacturer‐calibrated values and the shear‐wave elastography values. The intraclass correlation coefficient of muscle shear modulus was high: 0.978 between trials and 0.948 between days. Shear modulus increased linearly with elbow flexion torque across contraction intensity, and its slope was associated negatively with muscle strength. Conclusions: Muscle shear modulus measured with ultrasound shear‐wave elastography may be useful for inferring muscle stiffness across a wide range of contraction intensity. In addition, it has high repeatability between trials and between days. Muscle Nerve 50: 103–113, 2014
Recurrent central nervous system white matter changes in charcot–Marie–Tooth type X disease
Authors: Mckinney Jennifer L. , De Los Reyes Emily C. , Lo Warren D. , Flanigan Kevin M.
Published: October 2013

Introduction: X‐linked Charcot–Marie–Tooth (CMT1X) disease is caused by mutations in the GJB1 gene. We describe a young man who presented with recurrent central nervous symptoms and transient white matter changes in the setting of a novel mutation in the GJB1 gene. Methods: Evaluation included clinical examination, neuroimaging, electrophysiological, and molecular genetic studies. Results: Clinical examination on 2 admissions 5 years apart demonstrated hemiparesis with findings of underlying peripheral neuropathy. Electrophysiologic studies revealed a sensorimotor polyneuropathy. MRI studies from both admissions revealed white matter changes, with improvement on an intervening study. Mutation analysis showed a novel mutation (c.98T>A; p.Ile33Asn) in the GJB1 gene. Conclusions: Mutations in GJB1 can result in recurrent central nervous system symptoms with transient white matter signal changes on MRI. In patients presenting with hemiparesis, the presence of signs of a peripheral neuropathy may facilitate identification of CMT1X, and is likely to affect clinical management. Muscle Nerve 49:451–454, 2014
Proteomic analysis forTypeIinterferon antagonism ofJapanese encephalitis virusNS5 protein
Authors: Yang Tsuey‐Ching , Li Shih‐Wein , Lai Chien‐Chen , Lu Kai‐Zen , Chiu Man‐Tzu , Hsieh Tsung‐Han , Wan Lei , Lin Cheng‐Wen
Published: October 2013

Japanese encephalitis virus (JEV) nonstructural protein 5 (NS5) exhibits aTypeIinterferon (IFN) antagonistic function. This study characterizes Type IIFNantagonism mechanism ofNS5 protein, using proteomic approach. In human neuroblastoma cells,NS5 expression would suppressIFNβ‐induced responses, for example, expression ofIFN‐stimulated genesPKRandOASas well asSTAT1 nuclear translocation and phosphorylation. Proteomic analysis showedJEV NS5 downregulating calreticulin, while upregulating cyclophilinA,HSP60 and stress‐induced‐phosphoprotein 1. Gene silence of calreticulin raised intracellularCa2+levels while inhibiting nuclear translocalization ofSTAT1 andNFAT‐1 in response toIFNβ, thus, indicating calreticulin downregulation linked withTypeI IFNantagonism ofJEV NS5 via activation of Ca2+/calicineurin. Calcineurin inhibitor cyclosporin A attenuated NS5‐mediated inhibition ofIFNβ‐induced responses, for example,IFN‐sensitive response element driven luciferase,STAT1‐dependentPKRmRNAexpression, as well as phosphorylation and nuclear translocation ofSTAT1. Transfection with calcineurin (vs. control) siRNAenhanced nuclear translocalization ofSTAT1 and upregulatedPKRexpression inNS5‐expressing cells in response toIFNβ. Results proveCa2+, calreticulin, and calcineurin involvement inSTAT1‐mediated signaling as well as a key role ofJEV NS5 inTypeI IFNantagonism. This study offers insights into the molecular mechanism ofTypeIinterferon antagonism byJEV NS5.
Proteomics analysis of UV‐irradiated Lonicera japonicaThunb. with bioactive metabolites enhancement
Authors: Zhang Lin , Li Ximin , Zheng Wen , Fu Zhirong , Li Wenting , Ma Luyu , Li Ke , Sun Lianli , Tian Jingkui
Published: October 2013

A previous study showed that the contents of caffeoylquinic acids and iridoids, the major bioactive components in the postharvest Lonicera japonica Thunb., were induced by enhanced ultraviolet (UV)‐A or UV‐B irradiation. To clarify the UV‐responsive key enzymes in the bioactive metabolites biosynthetic pathway and the related plant defense mechanism in L. japonica, 2DE in combination with MALDI‐TOF/TOF MS was employed. Seventy‐five out of 196 differential proteins were positively identified. Based on the functions, these proteins were grouped into nine categories, covering a wide range of molecular processes including the secondary metabolites (caffeoylquinic acids and iridoids) biosynthetic‐related proteins, photosynthesis, carbohydrate and energy metabolism, stress, DNA, transport‐related proteins, lipid metabolism, amino acid metabolism, cell wall. Of note is the increasing expression of 1‐deoxy‐d‐xylulose 5‐phosphate reductoisomerase and 5‐enol‐pyruvylshikimate‐phosphate synthase, which was crucial to supply more precursor for the secondary metabolites including caffeoylquinic acids and iridoids. Thus, this study provides both the clues at the protein level for the increase of the two bioactive components upon UV irradiation and the profile of UV‐responsive proteins in L. japonica.
Memory chromic polyurethane with tetraphenylethylene
Authors: Wu You , Hu Jinlian , Huang Huahua , Li Jie , Zhu Yong , Tang Benzhong , Han Jianping , Li Liangbin
Published: October 2013

This article reports a chromic polymer, which is responsive to its shape memory properties and has both the behavior of shape memory polymers and chromic materials. We employed a strategy to fabricate such a smart material, which represents a new principle for making chromic materials. This material is made of shape memory polyurethane with tetraphenylethylene units (0.1 wt %) covalently connected to the soft‐segments (PCL, Mw = 4000). The material displays biocompatibility, shape fixity of 88–93%, and almost 100% shape recovery and has reversible mechanochromic, solvatochromic, and thermochromic shape memory effect. The memory chromism represented by the reversible change of emission intensity shows negative correlation with shape fixity, temperature, and existence of solvent. It may be explained that when the soft segments are molten or dissolved in solvent, the shape recovery switch is open, the AIE units are free from crystal binding and can migrate easily to larger areas, thus the AIE units/particles are far apart from each other and the barrier for rotation of phenyl groups is reduced, which lead to the reduction of emission intensity, appeared by no colors or pale colors, and vice versa. Since the switch is a fundamental structural character of SMPs, the shape memory properties have led to the chromism and we call this memory chromic. © 2013 Wiley Periodicals, Inc. J. Polym. Sci. Part B: Polym. Phys. 2014, 52, 104–110
Relaxation of backbone bond geometry improves protein energy landscape modeling
Authors: Conway Patrick , Tyka Michael D. , DiMaio Frank , Konerding David E. , Baker David
Published: October 2013

A key issue in macromolecular structure modeling is the granularity of the molecular representation. A fine‐grained representation can approximate the actual structure more accurately, but may require many more degrees of freedom than a coarse‐grained representation and hence make conformational search more challenging. We investigate this tradeoff between the accuracy and the size of protein conformational search space for two frequently used representations: one with fixed bond angles and lengths and one that has full flexibility. We performed large‐scale explorations of the energy landscapes of 82 protein domains under each model, and find that the introduction of bond angle flexibility significantly increases the average energy gap between native and non‐native structures. We also find that incorporating bonded geometry flexibility improves low resolution X‐ray crystallographic refinement. These results suggest that backbone bond angle relaxation makes an important contribution to native structure energetics, that current energy functions are sufficiently accurate to capture the energetic gain associated with subtle deformations from chain ideality, and more speculatively, that backbone geometry distortions occur late in protein folding to optimize packing in the native state.
Critical assessment of methods of protein structure prediction (CASP) — round x
Authors: Moult John , Fidelis Krzysztof , Kryshtafovych Andriy , Schwede Torsten , Tramontano Anna
Published: October 2013

This article is an introduction to the special issue of the journal PROTEINS, dedicated to the tenth Critical Assessment of Structure Prediction (CASP) experiment to assess the state of the art in protein structure modeling. The article describes the conduct of the experiment, the categories of prediction included, and outlines the evaluation and assessment procedures. The 10 CASP experiments span almost 20 years of progress in the field of protein structure modeling, and there have been enormous advances in methods and model accuracy in that period. Notable in this round is the first sustained improvement of models with refinement methods, using molecular dynamics. For the first time, we tested the ability of modeling methods to make use of sparse experimental three‐dimensional contact information, such as may be obtained from new experimental techniques, with encouraging results. On the other hand, new contact prediction methods, though holding considerable promise, have yet to make an impact in CASP testing. The nature of CASP targets has been changing in recent CASPs, reflecting shifts in experimental structural biology, with more irregular structures, more multi‐domain and multi‐subunit structures, and less standard versions of known folds. When allowance is made for these factors, we continue to see steady progress in the overall accuracy of models, particularly resulting from improvement of non‐template regions. Proteins 2014; 82(Suppl 2):1–6. © 2013 Wiley Periodicals, Inc.
Treatment options in the management of rosacea
Authors: Cowley Noreen
Published: October 2013

Rosacea can be triggered by many factors, and lifestyle advice, trigger avoidance and skin care should underpin drug treatment. Here, the author discusses the clinical subtypes of rosacea and the treatment options.