bluuebunny/crossref_metadata_2025 huggingface dataset:
Further characterization of Shwachman–Diamond syndrome: Psychological functioning and quality of life in adult and young patients
Authors: Perobelli Sandra , Nicolis Elena , Assael Baroukh Maurice , Cipolli Marco
Published: February 2012

To assess psychosocial functioning and quality of life in a representative group of adult and young patients with Shwachman–Diamond syndrome (SDS), all patients 3 years old and over included in the Italian SDS Registry were investigated using an ad‐hoc questionnaire for information about demography, education, socialization, rehabilitation therapy, and standardized questionnaires [SF‐36, Child Behavior Check‐List (CBCL)] for quality of life and behavior. Results were compared with those of a Cystic Fibrosis (CF) patient group, matched for age and sex. Eighty‐one percent of patients answered. All but one adult patient lived with their parents, 24% had independent income, and 57% had a driver's license. Different levels (from mild to severe) of cognitive impairment were reported by 76% of the adults and by 65% of the young patients. These data are significantly lower than those of the CF group. Both groups present low scores in the emotional and mental health evaluations at SF‐36, but SDS patients reported significantly more limitations in physical functioning (PF) and more body pain (BP) experiences. As reported by parents at CBCL, young SDS patients show more “social problems” (in the clinical area 31% SDS vs. 6% CF), “attention deficits disorder” (29% SDS vs. 0%CF), and “somatic complaints” (24% SDS vs. 12% CF). Psychosocial functioning is impaired in the majority of SDS patients, significantly more than in patients affected by CF. © 2012 Wiley Periodicals, Inc.
Complex relationship between meiotic recombination frequency and autosomal synaptonemal complex length per cell in normal human males
Authors: Pan Zhenzhen , Yang Qingling , Ye Nan , Wang Liu , Li Jianhua , Yu Dexin , Cooke Howard J. , Shi Qinghua
Published: February 2012

Although the relationship between meiotic recombination frequency and synaptonemal complex (SC) length has been of interest for a long time, how recombination frequency is related to SC length has not been carefully explored. To address this question, we have measured the meiotic recombination frequency as represented by MLH1 foci in 889 pachytene spermatocytes and measured the length of 19,558 autosomal SCs from 10 human males. A complex relationship between the number of MLH1 foci and total autosomal SC length per cell was observed. A positive correlation with significant correlation coefficients between the two variables was found in eight of the ten donors examined, with three donors showing weak correlation, and five showing moderate correlation. Two donors who did not show any correlation between the two variables were identified for the first time. Moreover, most cells with similar total autosomal SC length showed very different numbers of MLH1 foci both between individuals and even within an individual, and vice versa. Our data provide the first evidence for a complex relationship between the recombination frequency and total length of autosomal SCs per cell in human males. © 2012 Wiley Periodicals, Inc.
Hypertension and longitudinal changes in cerebral blood flow: The SMART‐MR study
Authors: Muller Majon , van der Graaf Yolanda , Visseren Frank L. , Mali Willem P. Th. M. , Geerlings Mirjam I. ,   for the SMART Study Group
Published: February 2012

Objective:

Cerebral hypoperfusion is among the mechanisms that may explain the association of high blood pressure (BP) with dementia. However, few data are available on the longitudinal association of hypertension and cerebral perfusion.

Methods:

We examined the longitudinal association of hypertension, BP, and antihypertensive drugs with change in parenchymal cerebral blood flow (pCBF) in 575 patients with manifest atherosclerotic disease (mean age, 57 ± 10 years) from the SMART‐MR study. Total CBF was measured at baseline and at follow‐up with magnetic resonance (MR) angiography and was expressed per 100ml brain volume as an indicator of cerebral perfusion. Automated brain segmentation was used to quantify brain tissue volumes and cerebrospinal fluid on MR imaging.

Results:

Mean (standard deviation [SD]) baseline pCBF was 52.3 (9.8) ml/min/100ml and after 3.9 years (range, 3.0–5.8 years) of follow‐up declined to 50.7 (10.3) ml/min/100ml. Regression analyses adjusted for age, sex, follow‐up time, and vascular risk showed that untreated and poorly controlled hypertension and higher levels of systolic and diastolic BP (per SD) were significantly associated with a decline in pCBF; mean differences in decline (95% confidence interval) were −2.2 (−4.4 to 0.0), −1.0 (−1.8 to −0.1), and −1.0 (−1.8 to −0.2) ml/min/100ml. In addition, within hypertensive patients (n = 469), patients using angiotensin receptor blockers (ARBs) did not show a decline in pCBF, whereas patients using other antihypertensive drugs did show a decline in pCBF.

Interpretation:

Untreated hypertension, poorly controlled hypertension, and high BP levels are associated with a decline in pCBF. In addition, treatment with ARBs might result in less decline in pCBF than other antihypertensive treatment.ANN NEUROL 2012
Allene in molekularen Materialien
Authors: Rivera‐Fuentes Pablo , Diederich François
Published: February 2012

Dieser Kurzaufsatz liefert eine kritische Übersicht über die Entwicklung allenhaltiger fortschrittlicher Funktionsmaterialien. Ausgehend von Entwurf und Synthese stabiler, enantiomerenreiner Bausteine wird eine Vielfalt von Systemen – wie formstabile Makrocyclen, Foldamere, Polymere, Charge‐Transfer‐Chromophore, Dendrimere, Flüssigkristalle und redoxschaltbare chirale Chromophore – bezüglich ihrer Herstellung, Eigenschaften und möglichen Anwendungen diskutiert. Ziel der Zusammenstellung ist es, einen Anreiz zur verstärkten Anwendung enantiomerenreiner Allene beim rationalen Entwurf neuer Funktionswerkstoffe zu liefern.
Improvements in barrier properties of poly(lactic acid) films coated with chitosan or chitosan/clay nanocomposite
Authors: Park Seok‐Hoon , Lee Hyun Soo , Choi Jae Hoon , Jeong Chang Myeong , Sung Myoung Hwan , Park Hyun Jin
Published: February 2012

The feasibility of chitosan or/and clay coatings as an alternative oxygen barrier material to poly(lactic acid) (PLA) film was investigated. The coated films were composed of natural materials based on biodegradable and biocompatible polymers, which exhibit excellent oxygen‐barrier properties compared with neat PLA films. Thus, these films can contribute toward effectively reducing environmental pollution. The chitosan/clay nanocomposite solutions were effectively dispersed through the clay using an ultrasonic bath and homogenizer. The barrier and morphology properties of the PLA films were tested by measuring selected film properties such as oxygen transmission rate (OTR), water vapor transmission rate (WVTR), field emission scanning electron microscopy, X‐ray diffraction and transmission electron microscope. OTR values measured using the chitosan and chitosan/clay nanocomposite coatings were significantly lower than those measured for neat PLA film. WVTR values measured using chitosan/clay nanocomposite coatings were also lower than those measured for neat PLA film and PLA film coated with chitosan. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Synthesis and Anti‐Oxidant Activity of (5E,9E)‐16‐(Substituted)‐7,8‐dihydro‐16λ5‐dibenzo[d,l][1,3,7,10,2]dioxadiazaphosphacyclotridecine‐16‐ones
Authors: Reddy Chinta Raveendra , Rani Chinthaparthi Radha , Sekhar Kuruva Chandra , Reddy Gangireddy Chandra Sekhar , Raju Chamarthi Naga
Published: February 2012

A new class of biologically active 13‐membered phosphorus‐macroheterocycles (6a–l) were conveniently synthesized from 1,2‐bis(salicylidene amino)‐phenylene (1), by treating with phosporusoxychloride (3) and followed by reacting with various aromatic thiols and amines (5f–l) in one path, and in another path 1 was directly treated with various phosphorodichloridates (2a–e) in the presence of triethylamine at 0–10°C under N2 atmosphere in THF. All the title compounds were confirmed by analytical and spectral data (IR, 1H‐, 13C‐, 31P‐NMR, and mass spectra) and screened for anti‐oxidant activity. Among these compounds, 6k, 6e, and 6l containing nitro, fluoro, and chloro groups as substituents on the phenyl ring exhibited high anti‐oxidant activity with effective inhibitory concentration (IC50) values.
Reactions of N3‐Substituted Amidrazones with cis‐1,2‐Cyclohexanedicarboxylic Anhydride and Biological Activities of the Products
Authors: Modzelewska‐Banachiewicz Bozena , Ucherek Marzena , Zimecki Michał , Kutkowska Jolanta , Kaminska Teresa , Morak‐Młodawska Beata , Paprocka Renata , Szulc Michał , Lewandowski Grzegorz , Marciniak Joanna , Bobkiewicz‐Kozlowska Teresa
Published: February 2012

A series of novel compounds were synthesized in reactions of N3‐substituted amidrazones with cis‐1,2‐cyclohexanedicarboxylic anhydride: linear, isoindole, and triazole derivatives. All new structures were confirmed by H1 NMR and IR spectrometry as well as elemental analysis. Potential biological effects of new compounds were predicted with the Prediction of Activity Spectra for Substances (PASS) program. Antiviral, antibacterial, analgesic, and anti‐inflammatory activities were experimentally verified.
Very high levels of anti–citrullinated protein antibodies are associated with HLA–DRB1*15 non–shared epitope allele in patients with rheumatoid arthritis
Authors: Laki Judit , Lundström Emeli , Snir Omri , Rönnelid Johan , Ganji Izabella , Catrina Anca I. , Bengtsson Camilla , Saevarsdottir Saedis , Wick Marius C. , Alfredsson Lars , Klareskog Lars , Padyukov Leonid
Published: February 2012

Objective

Production of anti–citrullinated protein antibodies (ACPAs) is an important biomarker for rheumatoid arthritis (RA). We undertook this study to determine whether genetic factors (HLA—DRB1 alleles) are associated with extreme ACPA levels in individuals with ACPA‐positive RA, and to ascertain whether there are any phenotypic characteristics associated with these subgroups of RA.

Methods

HLA–DRB1 allelic groups were genotyped in 1,073 ACPA‐positive RA patients from the Swedish Epidemiological Investigation of Rheumatoid Arthritis study. We found that 283 patients (26.4%) had high ACPA levels (defined as >1,500 units/ml using the Euro‐Diagnostica anti‐CCP2 test), while the rest of the patients had moderate ACPA levels and served as the comparison group. A replication group consisted of 235 RA patients.

Results

No significant differences in baseline disease activity were observed between patients with high and those with moderate ACPA levels. However, the HLA–DRB1*15 allele was associated with high ACPA levels (P = 0.0002). A similar trend was detected in HLA–DRB1*15–positive patients in the replication cohort, with meta‐analysis of the discovery and replication cohorts demonstrating an overall effect of HLA–DRB1*15 on development of high ACPA levels in both the discovery and replication cohorts (P < 0.0001 by Mantel‐Haenszel test with a fixed‐effects model).

Conclusion

Our data indicate that HLA–DRB1*15 may promote the production of high ACPA levels. Due to the high value of ACPA level scores in the 2010 American College of Rheumatology/European League Against Rheumatism classification criteria for RA, the presence of HLA–DRB1*15 may, at least in part, contribute to fulfilling the criteria for RA. This illustrates the complex nature of the genetic regulation of ACPA levels. Additional mechanistic studies of the regulation of ACPAs and ACPA‐positive RA are pending.
Associations of varus thrust and alignment with pain in knee osteoarthritis
Authors: Lo Grace H. , Harvey William F. , McAlindon Timothy E.
Published: February 2012

Objective

To investigate associations of varus thrust and varus static alignment with pain in patients with knee osteoarthritis (OA).

Methods

This was a cross‐sectional study of participants from a randomized controlled trial of vitamin D treatment for knee OA. Participants were video recorded while walking and scored for presence of varus thrust. Static alignment was measured on standard posteroanterior knee radiographs. Pain questions from the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) questionnaire were used to assess symptoms. We calculated means for total WOMAC pain in relation to varus thrust and static varus alignment (i.e., corrected anatomic alignment <178 degrees). Ordinal logistic regressions were performed, with responses on individual WOMAC pain questions as the outcomes and varus thrust and varus alignment as the predictors.

Results

There were 82 participants, 60% of whom were female. The mean ± SD age was 65.1 ± 8.5 years, and the mean ± SD body mass index was 30.2 ± 5.4 kg/m2. The mean total WOMAC pain score was 6.3 versus 3.9, respectively, in those with versus without definite varus thrust (P = 0.007) and 5.0 versus 4.2 in those with versus without varus alignment (P = 0.36). Odds ratios for pain with walking and standing were 4.7 (95% confidence interval 1.8–11.9) and 5.5 (95% confidence interval 2.2–14.2), respectively, in those with and those without definite varus thrust. There were no significant associations between varus alignment and responses to individual WOMAC pain questions. Sensitivity analyses suggested that varus classified using a more stringent definition might have been associated with pain on walking and standing.

Conclusion

In patients with knee OA, varus thrust, and possibly varus static alignment, were associated with pain, specifically during weight‐bearing activities. Treatment of varus thrust (e.g., via bracing or gait modification) may lead to improvement of symptoms.
Necessary and Sufficient Conditions for Consensus of Delayed Fractional‐order Systems
Authors: Shen Jun , Cao Jinde
Published: February 2012

In this paper, we study the consensus problem of fractional‐order systems with input delays. Using Laplace transform method, the stability of the fractional‐order systems is first discussed in the frequency domain. Based on the generalized Nyquist stability criterion, a necessary and sufficient condition is further derived to ensure the consensus of fractional‐order systems with identical input delays over directed interaction topology. Furthermore, when the interaction topology is undirected, the consensus condition of fractional‐order systems with heterogeneous input delays is explicitly given. Finally, some illustrative examples are presented to show the effectiveness and advantages of the theoretical results.
Optimal Performance in Tracking Stochastic Signal Under Disturbance Rejection
Authors: Zhan Xi‐Sheng , Guan Zhi‐Hong , Liao Rui‐Quan , Yuan Fu‐Shun
Published: February 2012

The analysis method of optimal tracking performance is proposed for multiple‐input multiple‐output (MIMO) linear time‐invariant (LTI) systems under disturbance rejection. An H2 criterion of the error signal between the output of the plant and the reference signal is used as a measure for the tracking performance. Spectral factorization is applied to obtain the optimal solution of the system tracking error. The explicit expressions are derived for this minimal tracking error with respect to random reference signals under disturbance rejection. It is shown that the nonminimum phase zeros, the zero direction, the unstable poles, the pole direction of a given plant, statistical characteristics of the reference input signal, and disturbance signal have a negative effect on a feedback system's ability to reduce the system error with disturbance rejection. The results show that the optimal tracking performance will further be damaged because of disturbance rejection. Some typical examples are given to illustrate the theoretical results.
Combining time‐resolved fluorescence with synchronous fluorescence spectroscopy to study bovine serum albumin‐curcumin complex during unfolding and refolding processes
Authors: Barakat Christelle , Patra Digambara
Published: February 2012

We investigated the complex interaction between bovine serum albumin (BSA) and curcumin by combining time‐resolved fluorescence and synchronous fluorescence spectroscopy. The interaction was significant and sensitive to fluorescence lifetime and synchronous fluorescence characteristics. Binding of curcumin significantly shortened the fluorescence lifetime of BSA with a bi‐molecular quenching rate constant of kq = 3.17 × 1012 M‐1s‐1. Denaturation by urea unfolded the protein molecule by quenching the fluorescence lifetime of BSA. The tyrosine synchronous fluorescence spectra were blue shifted whereas the position of tryptophan synchronous fluorescence spectra was red shifted during the unfolding process. However, denaturation of urea had little effect on the synchronous fluorescence peak of tyrosine in curcumin‐BSA complex except in the low concentration range; however, it shifted the peak to the red, indicating that curcumin shifted tryptophan moiety to a more polar environment in the unfolded state. Decreases in the time‐resolved fluorescence lifetime and curcumin‐BSA complex during unfolding were recovered during refolding of BSA by a dilution process, suggesting partial reversibility of the unfolding process for both BSA and curcumin‐BSA complex. Copyright © 2012 John Wiley & Sons, Ltd.
Ab initio protein modeling into CryoEM density maps using EM‐Fold
Authors: Lindert Steffen , Hofmann Tommy , Wötzel Nils , Karakaş Mert , Stewart Phoebe L. , Meiler Jens
Published: February 2012

EM‐Fold was used to build models for nine proteins in the maps of GroEL (7.7 Å resolution) and ribosome (6.4 Å resolution) in the ab initio modeling category of the 2010 cryo‐electron microscopy modeling challenge. EM‐Fold assembles predicted secondary structure elements (SSEs) into regions of the density map that were identified to correspond to either α‐helices or β‐strands. The assembly uses a Monte Carlo algorithm where loop closure, density‐SSE length agreement, and strength of connecting density between SSEs are evaluated. Top‐scoring models are refined by translating, rotating, and bending SSEs to yield better agreement with the density map. EM‐Fold produces models that contain backbone atoms within SSEs only. The RMSD values of the models with respect to native range from 2.4 to 3.5 Å for six of the nine proteins. EM‐Fold failed to predict the correct topology in three cases. Subsequently, Rosetta was used to build loops and side chains for the very best scoring models after EM‐Fold refinement. The refinement within Rosetta's force field is driven by a density agreement score that calculates a cross‐correlation between a density map simulated from the model and the experimental density map. All‐atom RMSDs as low as 3.4 Å are achieved in favorable cases. Values above 10.0 Å are observed for two proteins with low overall content of secondary structure and hence particularly complex loop modeling problems. RMSDs over residues in secondary structure elements range from 2.5 to 4.8 Å. © 2012 Wiley Periodicals, Inc. Biopolymers 97: 669–677, 2012.
N‐glycosylation of enhanced aromatic sequons to increase glycoprotein stability
Authors: Price Joshua L. , Culyba Elizabeth K. , Chen Wentao , Murray Amber N. , Hanson Sarah R. , Wong Chi‐Huey , Powers Evan T. , Kelly Jeffery W.
Published: February 2012

N‐glycosylation can increase the rate of protein folding, enhance thermodynamic stability, and slow protein unfolding; however, the molecular basis for these effects is incompletely understood. Without clear engineering guidelines, attempts to use N‐glycosylation as an approach for stabilizing proteins have resulted in unpredictable energetic consequences. Here, we review the recent development of three “enhanced aromatic sequons,” which appear to facilitate stabilizing native‐state interactions between Phe, Asn‐GlcNAc and Thr when placed in an appropriate reverse turn context. It has proven to be straightforward to engineer a stabilizing enhanced aromatic sequon into glycosylation‐naïve proteins that have not evolved to optimize specific protein–carbohydrate interactions. Incorporating these enhanced aromatic sequons into appropriate reverse turn types within proteins should enhance the well‐known pharmacokinetic benefits of N‐glycosylation‐based stabilization by lowering the population of protease‐susceptible unfolded and aggregation‐prone misfolded states, thereby making such proteins more useful in research and pharmaceutical applications. © 2011 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 98: 195–211, 2012.
Effects of Lys2 to Ala2 substitutions on the structure and potency of ω‐conotoxins MVIIA and CVID
Authors: Schroeder Christina I. , Nielsen Katherine J. , Adams Denise A. , Loughnan Marion , Thomas Linda , Alewood Paul F. , Lewis Richard J. , Craik David J.
Published: February 2012

Lys2 has previously been implicated as a residue important in binding interactions between ω‐conotoxins and the N‐type calcium channel. To further assess the importance of this residue, Lys2 to Ala2 derivatives of ω‐conotoxins MVIIA and CVID were synthesized and their structures and binding potencies determined. A comparison of the 3D structures of the Ala2 mutants with the parent peptides suggest there are significant structural differences brought about by this substitution. In particular, stabilizing interactions between Lys2 and loop 2 of the ω‐conotoxins are removed, leading to greater flexibility in loop 2, which contains Tyr13, a crucial residue for ω‐conotoxin binding to the N‐ and P/Q‐type voltage‐gated calcium channel (VGCC). The significant drop in binding potencies resulting from replacement of Lys2 thus appears to relate more to entropic factors than to any direct interaction of Lys2 with the VGCC. This has significant implications for the development of a pharmacophore binding model for ω‐conotoxins, as removal of Lys2 from consideration suggests that the ω‐conotoxins residues that interact with the N‐type VGCC reside in loop 2 and 4, and thus cover a significantly smaller and more defined area of the surface of ω‐conotoxin than previously thought. © 2012 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 98: 345–356, 2012.
Efficient Synthesis of C2v‐Symmetrical Pentakisadducts of C60 as Versatile Building Blocks for Fullerene Architectures that Involve a Mixed Octahedral Addition Pattern
Authors: Hörmann Frank , Donaubauer Wolfgang , Hampel Frank , Hirsch Andreas
Published: February 2012

We report here on the selective synthesis of fullerene pentakisadducts 3 with an incomplete octahedral addition pattern by means of mixed [5:1]hexakisadducts 1 that involve an isoxazoline moiety as a protection group. The isoxazoline addend can be cleanly cleaved by irradiation with light. By using this protection–deprotection strategy, a variety of fullerene pentakisadducts 3 were synthesized in 29–44 % overall yield without the need of HPLC purification. This novel photolytic deprotection of 1 can be explained by an initial electron transfer that leads to a biradical, which can easily eliminate the isoxazoline added. The very efficient and straightforward syntheses of the bisfullerene 4 and the globular hexakisadduct 7, each of which involves mixed octahedral addition patterns, clearly demonstrate the advantage of fullerene pentakisadducts 3 as suitable precursors for the construction of highly functional and complex [5:1]hexakisadduct architectures. Complete structural characterization of all new compounds was carried out by MALDI mass spectrometry, UV/Vis, FTIR, 1H NMR and 13C NMR spectroscopy, as well as X‐ray diffraction.
Total Synthesis of Laulimalide: Synthesis of the Northern and Southern Fragments
Authors: Trost Barry M. , Seganish W. Michael , Chung Cheol K. , Amans Dominique
Published: February 2012

The first stage in the development of a synthetic route for the total synthesis of laulimalide (1) is described. Our retrosynthetic analysis envisioned a novel macrocyclization route to the natural product by using a Ru‐catalyzed alkene–alkyne coupling. This would be preceded by an esterification of the C19 hydroxyl group, joining together two equally sized synthons, the northern fragment 7 and the southern fragment 8. Our first generation approach to the northern fragment entailed a key sequential Ru/Pd coupling sequence to assemble the dihydropyran. The key reactions proceeded smoothly, but the inability to achieve a key olefin migration led to the development of an alternative route based on an asymmetric dinuclear Zn‐catalyzed aldol reaction of a hydroxyl acylpyrrole. This key reaction led to the desired diol adduct 66 with excellent syn/anti selectivity (10:1), and allowed for the successful completion of the northern fragment 7. The key step for the synthesis of the southern fragment was a chemoselective Rh‐catalyzed cycloisomerization reaction to form the dihydropyran ring from a diyne precursor. This reaction proved to be selective for the formation of a six‐membered ring, over a seven. The use of an electron‐deficient bidentate phosphine allowed for the reaction to proceed with a reduced catalyst loading.
A Concise Total Synthesis of Deoxyschizandrin and Exploration of Its Antiproliferative Effects and those of Structurally Related Derivatives
Authors: Zheng Shaojun , Aves Sarah J. , Laraia Luca , Galloway Warren R. J. D. , Pike Kurt G. , Wu Wenjun , Spring David R.
Published: February 2012

The natural product deoxyschizandrin has been shown to have a wide range of biological activities. In recent years the therapeutic potential of this compound against cancers has attracted significant interest. Herein we describe a concise de novo total synthesis of deoxyschizandrin based around a double organocuprate oxidation strategy. In addition, we present the results of biological studies exploring the ability of deoxyschizandrin and synthetic precursors lacking the medium ring biaryl unit to inhibit the proliferation of a human cancer cell line. These studies led to the identification of a structurally novel agent with in vitro anticancer activity.
Deconstructing signal transduction pathways that regulate the actin cytoskeleton in dendritic spines
Authors: Penzes Peter , Cahill Michael E.
Published: February 2012

Dendritic spines are the sites of most excitatory synapses in the central nervous system. Recent studies have shown that spines function independently of each other, and they are currently the smallest known processing units in the brain. Spines exist in an array of morphologies, and spine structure helps dictate synaptic function. Dendritic spines are rich in actin, and actin rearrangements are critical regulators of spine morphology and density. In this review, we discuss the importance of actin in regulating dendritic spine morphogenesis, and discuss the upstream signal transduction pathways that either foster or inhibit actin polymerization. The understanding of actin regulatory pathways is best conceptualized as a hierarchical network in which molecules function in discrete levels defined by their molecular distance to actin. To this end, we focus on several classes of molecules, including guanine nucleotide exchange factors, small GTPases, small GTPase effectors, and actin binding proteins. We discuss how individual proteins in these molecular classes impact spine morphogenesis, and reveal the biochemical interactions in these networks that are responsible for shaping actin polymerization. Finally, we discuss the importance of these actin regulatory pathways in neuropsychiatric disorders. © 2012 Wiley Periodicals, Inc.
Generalized Transition Waves and Their Properties
Authors: Berestycki Henri , Hamel François
Published: February 2012

In this paper, we generalize the usual notions of waves, fronts, and propagation speeds in a very general setting. These new notions, which cover all usual situations, involve uniform limits, with respect to the geodesic distance, to a family of hypersurfaces that are parametrized by time. We prove the existence of new such waves for some time‐dependent reaction‐diffusion equations, as well as general intrinsic properties, some monotonicity properties, and some uniqueness results for almost‐planar fronts. The classification results, which are obtained under some appropriate assumptions, show the robustness of our general definitions. © 2012 Wiley Periodicals, Inc.
Parallel solution of the subset‐sum problem: an empirical study
Authors: Bokhari Saniyah S.
Published: February 2012

The subset‐sum problem is a well‐known NP‐complete combinatorial problem that is solvable in pseudo‐polynomial time, that is, time proportional to the number of input objects multiplied by the sum of their sizes. This product defines the size of the dynamic programming table used to solve the problem. We show how this problem can be parallelized on three contemporary architectures, that is, a 128‐processor Cray Extreme Multithreading (XMT) massively multithreaded machine, a 16‐processor IBM x3755 shared memory machine, and a 240‐core NVIDIA FX 5800 graphics processing unit (GPU). We show that it is straightforward to parallelize this algorithm on the Cray XMT primarily because of the word‐level locking that is available on this architecture. For the other two machines, we present an alternating word algorithm that can implement an efficient solution. Our results show that the GPU performs well for problems whose tables fit within the device memory. Because GPUs typically have memories in the order of 10GB, such architectures are best for small problem sizes that have tables of size approximately 1010. The IBM x3755 performs very well on medium‐sized problems that fit within its 64‐GB memory but has poor scalability as the number of processors increases and is unable to sustain performance as the problem size increases. This machine tends to saturate for problem sizes of 1011 bits. The Cray XMT shows very good scaling for large problems and demonstrates sustained performance as the problem size increases. However, this machine has poor scaling for small problem sizes; it performs best for problem sizes of 1012 bits or more. The results in this paper illustrate that the subset‐sum problem can be parallelized well on all three architectures, albeit for different ranges of problem sizes. The performance of these three machines under varying problem sizes show the strengths and weaknesses of the three architectures. Copyright © 2012 John Wiley & Sons, Ltd.
On frequency response and stability of an optical front–end with variable‐gain current amplifier using a bipolar junction transistor translinear loop
Authors: Tadić Nikša , Zogović Milena , Gaberl Wolfgang , Zimmermann Horst
Published: February 2012

A comparative analysis of implementations of an optical front–end with variable transimpedance intended for optical storage systems in two different BiCMOS technologies is given in this article. The variable‐gain current amplifier within the optical front–end is designed by using a modified balanced type of the bipolar junction transistors translinear loop. The predictions of the optical front–end mathematical models are confirmed by the measured results. They show that a 0.6‐µm BiCMOS silicon technology implementation with worse bipolar junction transistor parameters (unity‐gain frequency, current gain β, and the Early voltage) gives much better stability than a 0.35‐µm BiCMOS silicon‐germanium technology implementation. As a consequence, the useful measured transimpedance dynamic range of the proposed optical front–end is 17.5 times larger in the 0.6‐µm BiCMOS silicon technology than that in the 0.35‐µm BiCMOS silicon‐germanium technology. Copyright © 2012 John Wiley & Sons, Ltd.
Negative density‐dependent dispersal in the American black bear (Ursus americanus) revealed by noninvasive sampling and genotyping
Authors: Roy Justin , Yannic Glenn , Côté Steeve D. , Bernatchez Louis
Published: February 2012

Although the dispersal of animals is influenced by a variety of factors, few studies have used a condition‐dependent approach to assess it. The mechanisms underlying dispersal are thus poorly known in many species, especially in large mammals. We used 10 microsatellite loci to examine population density effects on sex‐specific dispersal behavior in the American black bear,Ursus americanus. We tested whether dispersal increases with population density in both sexes. Fine‐scale genetic structure was investigated in each of four sampling areas using Mantel tests and spatial autocorrelation analyses. Our results revealed male‐biased dispersal pattern in low‐density areas. As population density increased, females appeared to exhibit philopatry at smaller scales. Fine‐scale genetic structure for males at higher densities may indicate reduced dispersal distances and delayed dispersal by subadults.
Identity and relationships of the Arboreal Caatinga among other floristic units of seasonally dry tropical forests (SDTFs) of north‐eastern and Central Brazil
Authors: Santos Rubens M. , Oliveira‐Filho Ary T. , Eisenlohr Pedro V. , Queiroz Luciano P. , Cardoso Domingos B. O. S. , Rodal Maria J. N.
Published: February 2012

The tree species composition of seasonally dry tropical forests (SDTF) in north‐eastern and central Brazil is analyzed to address the following hypotheses: (1) variations in species composition are related to both environment (climate and substrate) and spatial proximity; (2) SDTF floristic units may be recognized based on peculiar composition and environment; and (3) the Arboreal Caatinga, a deciduous forest occurring along the hinterland borders of the Caatinga Domain, is one of these units and its flora is more strongly related to the caatinga vegetation than to outlying forests. The study region is framed by the Brazilian coastline, 50th meridian west and 21st parallel south, including the Caatinga Domain and extensions into the Atlantic Forest and Cerrado Domains. Multivariate and geostatistic analyses were performed on a database containing 16,226 occurrence records of 1332 tree species in 187 georeferenced SDTF areas and respective environmental variables. Tree species composition varied significantly with both environmental variables and spatial proximity. Eight SDTF floristic units were recognized in the region, including the Arboreal Caatinga. In terms of species composition, its tree flora showed a stronger link with that of the Cerrado Dry Forest Enclaves. On the other hand, in terms of species frequency across sample areas, the links were stronger with two other units: Rock Outcrops Caatinga and Agreste and Brejo Dry Forests. There is a role for niche‐based control of tree species composition across the SDTFs of the region determined primarily by the availability of ground water across time and secondarily by the amount of soil mineral nutrients. Spatial proximity also contributes significantly to the floristic cohesion of SDTF units suggesting a highly dispersal‐limited tree flora. These units should be given the status of eco‐regions to help driving the conservation policy regarding the protection of their biodiversity.
Two Environmentally Friendly Energetic Compounds, [Mn(AZT)4(H2O)2](PA)2·4H2O and [Co(AZT)2(H2O)4](PA)2, Based on 3‐Azido‐1,2,4‐triazole (AZT) and Picrate (PA)
Authors: Wu Bi‐Dong , Zhang Jian‐Guo , Zhang Tong‐Lai , Yang Li , Zhou Zun‐Ning
Published: February 2012

Two multiligand coordination compounds, [Mn(AZT)4(H2O)2](PA)2·4H2O (1) and [Co(AZT)2(H2O)4](PA)2 (2), were synthesized with 3‐azido‐1,2,4‐triazole (AZT) as a ligand and picrate (PA) as a counteranion and characterized by elemental analysis and FTIR spectroscopy. The crystal structures were determined by single‐crystal X‐ray diffraction. The results show that the crystals of 1 and 2 have a triclinic space group (P$\bar {1}$) and orthorhombic space group (Pbca), respectively. Moreover, 1 and 2 have distorted octahedral structures. Their thermal decomposition mechanisms were investigated by differential scanning calorimetry and thermogravimetric analysis. The experimental data showed that the energies of combustion were approximately equal to the energies of combustion of 1,3,5‐trinitro‐1,3,5‐triazacyclohexane (RDX) and 1,3,5,7‐tetranitro‐1,3,5,7‐tetraazocane (HMX). The nonisothermal kinetic parameters were studied by applying the methods of Kissinger and Ozawa. The sensitivity properties showed that 1 and 2 had a higher flame sensitivity than 2,4,6‐trinitrotoluene, RDX, and HMX.
A Facile Approach for Transferring PbS Colloidal Photonic Structures into Alkanol Solutions and Composite Solid Films
Authors: Li Chunguang , Bai Tianyu , Li Tao , Li Feifei , Dong Wenjun , Shi Zhan , Feng Shouhua
Published: February 2012

Visible‐light‐responsive photonic structures have been prepared in alcohol solvents by using silica‐modified PbS colloidal nanocrystal clusters (CNCs) as building blocks. Further modification of the PbS CNCs with a coating of silica allowed the dispersion of the particles into nonaqueous solutions. Repulsive electrostatic and solvation forces contribute to the self‐assembly of the PbS@SiO2 spheres. The core–shell particles have optical properties similar to those of CNCs, and they can also be assembled into close‐packing films through simple drop‐casting on silicon substrates. Embedding droplets of such a PbS@SiO2 colloidal solution in a polymer matrix produced solid composite materials with visible‐light‐responsive optical properties with potential applications as sensors and optical switches.
Complex‐Induced Proximity Effect in the Regioselective Lithiation of Pyridine Derivatives
Authors: Dhau Jaspreet S. , Singh Amritpal , Kasetti Yoganjaneyulu , Bharatam P. V.
Published: February 2012

The regioselective ring lithiation of BF3‐complexed 3‐picoline (1a), 3,4‐lutidine (1b), and 3,5‐lutidine (1c) was studied. The dilithiation of 1a, 1b, and 1c was also investigated to experimentally explore the relative preference of the sites on the substituted pyridine ring for lithiation. The role of the complex‐induced proximity effect (CIPE) for inducing lithiation in these moieties was investigated using both experimental and computational studies.
Regioselective Photochemical C–OMe Bond Formation Initiated by One‐Electron Transfer and N–OMe Bond Fragmentation in Electron Donor–Acceptor Systems
Authors: Collado Daniel , Perez‐Inestrosa Ezequiel
Published: February 2012

Compounds that integrate electron donor–acceptor subunits with N‐methoxyisoquinolinium as acceptors and substituted (methoxy)benzenes as donors were synthesized and their luminescent and photochemical properties studied. Photolysis yielded the corresponding photomethoxylation products in a two‐step process that involves N–OMe bond scission followed by C–OMe bond formation. Homolysis of the N–OMe bond restores the aromatic isoquinoline nucleus and produces a methoxy radical that can couple to the required ring carbon atom in the benzene cation radical to give the products in a regioselective process controlled by the spin density of the cation radical. This photoprocess involves two different pathways: methoxylation of the acceptor (intracomponent methoxylation) or the donor (intercomponent metoxylation). Both methoxy‐transfer pathways are controlled by the donoating ability (redox potential) of the donor subunit, consistent with the emission observed upon excitation of the charge‐transfer state in systems that undergo intermethoxylation.
Synthesis of 6‐Substituted 2(1H)‐Pyridon‐3‐yl C‐2′‐Deoxyribonucleosides
Authors: Chapuis Hubert , Kubelka Tomáš , Joubert Nicolas , Pohl Radek , Hocek Michal
Published: February 2012

Two approaches to the synthesis of the title 6‐substituted 2(1H)‐pyridon‐3‐yl C‐2′‐deoxyribonucleosides have been pursued. A protected 6‐aminopyridine C‐nucleoside intermediate was converted into the N‐oxide followed by Ac2O‐mediated rearrangement and final deprotection to give 6‐acetylamino‐2‐oxo(1H)‐pyridin‐3‐yl deoxyribonucleoside. Due to the unusually high stability of the N‐acetyl group, the full deprotection was unsuccessful. In the second approach, 6‐chloro‐2‐pyridone was converted into phosphorodiamidate, which underwent ortho‐magnesiation and iodination to give the 3‐iododerivative. It was then used in a Heck coupling with a sugar glycal and the resulting product deprotected to give 6‐chloro‐2‐oxo(1H)‐pyridin‐3‐yl deoxyribonucleoside, which was either directly or after reprotection converted into 6‐methyl‐, 6‐amino‐, and 6‐unsubstituted pyridone C‐nucleosides. The final nucleosides were very unstable and easily epimerized and/or oxidized, which limits (but not excludes) their further use in chemical biology.
Cicindeloine from Stenus cicindeloides – Isolation, Structure Elucidation, and Total Synthesis
Authors: Müller Tobias , Göhl Matthias , Lusebrink Inka , Dettner Konrad , Seifert Karlheinz
Published: February 2012

The new piperideine alkaloid cicindeloine (3) was isolated from the pygidial glands of the beetles Stenus cicindeloides and Stenus solutus. The structure and absolute configuration of 3 were elucidated by NMR spectroscopy and asymmetric synthesis, respectively. A very efficient gram‐scale synthesis of 3 was developed using an intramolecular aza‐Wittig reaction as the final step. The synthetic route is comprised of 12 steps and proceeds in 20 % total yield. Nine of the 12 steps were conducted without column chromatography.
Solvent‐Free Tandem Synthesis of 2‐Thiazolines and 2‐Oxazolines Catalyzed by a Copper Catalyst
Authors: Li Xiangnan , Zhou Baoyue , Zhang Jin , She Mengyao , An Shujuan , Ge Haixia , Li Cong , Yin Bing , Li Jianli , Shi Zhen
Published: February 2012

Tandem reactions of nitriles with 2‐aminoethanethiol hydrochloride or amino alcohols in the presence of a catalytic amount of cupric methacrylate (CuII2L4, L = methacrylate) were employed to prepare 2‐thiazolines and 2‐oxazolines under mild reaction conditions. The synthetic procedure showed high selectivity for the synthesis of mono‐ and bis‐thiazolines and oxazolines, and a variety of 2‐thiazolines and 2‐oxazolines was obtained in good to excellent yields.
Size Dependant Electrochemical Behavior of Silver Nanoparticles with Sizes of 10, 20, 40, 80 and 107 nm
Authors: Giovanni Marcella , Pumera Martin
Published: February 2012

The direct detection of metal nanoparticles is of high importance. Here we investigate inherent electrochemistry of silver nanoparticles of sizes 10, 40, 80 and 107 nm by means of cyclic voltammetry.
Effects of the hydrodynamic environment and oxygen mass transfer on plant cell growth and milk‐clotting protease production in a stirred‐tank reactor
Authors: Raposo Sara , Lima‐Costa Maria Emília
Published: February 2012

Industrial‐scale plant cell based bioprocesses are limited because of technological challenges associated with mass transfer and mixing in the heterogeneous broth, which typically displays non‐Newtonian characteristics. Cultures of Centaurea calcitrapa cells, presenting milk‐clotting activity, were established in a 7‐L stirred‐tank reactor (STR), keeping the initial mass transfer conditions constant, to gain a better understanding of the effects of the hydrodynamic environment and mass transfer on protease production. Cell suspensions grown in an STR equipped with one single marine propeller or two Rushton turbines showed the highest protease activities and biomass production, corresponding to the adequate mass transfer achieved under the tested bioreactor conditions. The key factors improving milk‐clotting protease production in a bioreactor were an efficient mass transfer and good bulk mixing without the formation of stagnant zones, while a compromise had to be established in relation to the hydrodynamic shear conditions.
Nonlinear behavior of high‐damping rubber bearings under horizontal bidirectional loading: full‐scale tests and analytical modeling
Authors: Yamamoto Masashi , Minewaki Shigeo , Yoneda Harumi , Higashino Masahiko
Published: February 2012

Horizontal bidirectional loading tests are conducted for real‐sized high‐damping rubber (HDR) bearings with diameters of 700 mm (HDR700) and 1300 mm (HDR1300). The hysteresis loops of these bearings under bidirectional horizontal loadings are compared with those under unidirectional loadings. The results show that the bearing force measurement in the primary direction of loading increases when there is displacement in the orthogonal direction. Unusually, the maximum restoring force in the orthogonal direction to the primary loading direction occurs near zero displacement. On the basis of the observations of the restoring forces, a rate‐independent model is proposed. This model simulates well the test results under both bidirectional loading and unidirectional loading. It can reproduce the irregular restoring forces characteristics around zero displacement as described above. Bidirectional loading induced twist deformation in the HDR bearings that increased local shear strains. This phenomenon results in an early failure as observed in HDR700. The additional shear strain is estimated based on the twist deformation measured by video image analysis. The comparison of the nominal total shear stress demonstrates that the increase of shear stress because of bidirectional loading occurs when the average shear strain is larger than about 200%. The larger the shear strain, the greater the bidirectional effect. It is shown that the nominal total shear stress of average strain of 350% under bidirectional circular loading pattern is approximately the same as the average shear strain of 400% under unidirectional loading. This means that the average shear strain of 350% under a bidirectional circular loading corresponds to a local shear strain of 400%. Copyright © 2012 John Wiley & Sons, Ltd.
Contribution of germline mutations to PARK2 gene inactivation in lung adenocarcinoma
Authors: Iwakawa Reika , Okayama Hirokazu , Kohno Takashi , Sato‐Otsubo Aiko , Ogawa Seishi , Yokota Jun
Published: February 2012

Homozygous germline mutations of the PARK2 gene are responsible for the development of early‐onset Parkinson's disease (PD). Homozygous PARK2 mutations have been also detected in lung adenocarcinoma (LADC). However, since heterozygous PARK2 germline mutations are present in a subset of non‐PD individuals, the timing for the occurrence of two‐hit PARK2 mutations in LADC progression is unclear. Therefore, we comprehensively analyzed mutations, expression and copy number variations of the PARK2 gene in 267 primary LADCs together with the corresponding noncancerous lung cells and 39 LADC cell lines. Heterozygous germline exonic deletions were detected in five patients with LADC, and loss of heterozygosity including the PARK2 locus was detected in 31/267 (11.6%) LADCs. However, homozygous PARK2 inactivation was not detected in any of them, including the five patients with germline mutations. Homozygous PARK2 inactivation was detected in 6/39 (15%) cell lines, two exonic deletions, one exonic duplication, and three point mutations, while heterozygous PARK2 inactivation was detected in two cell lines (both by exonic deletions). These results strongly indicate that somatic PARK2 mutations occur rarely (or do not occur) in LADC development and that germline PARK2 mutations could contribute to LADC progression but not to LADC development. © 2012 Wiley Periodicals, Inc.
Development of adsorbents for CO2 capture from waste materials: a review
Authors: Olivares‐Marín Mara , Maroto‐Valer M. Mercedes
Published: February 2012

In recent years, a number of scientific papers have been published on the use of residues from industrial and agricultural operations to develop adsorbents for CO2 capture at low, medium, and high temperatures. This is mainly because these waste materials are low‐cost and abundant, and may contribute to a reduction of the total costs in carbon capture technologies. In addition, environmental concerns may also be addressed by developing strategies that can use these waste materials instead of burning or sending them to landfills. This review analyses the recent progress made in the development of CO2 adsorbents made from waste precursors. The different preparation approaches developed for the synthesis of adsorbents, including type of raw waste‐material, experimental methods, and further modifications, are reviewed. © 2012 Society of Chemical Industry and John Wiley & Sons, Ltd