bluuebunny/crossref_metadata_2025_split huggingface dataset:
Protein Misfolding and Degradation in Genetic Disease
Authors: Bross Peter , Andresen Brage S , Corydon Thomas J , Gregersen Niels 
Published: February 2011

AbstractMolecular disease mechanisms in inherited diseases often spotlight missense mutations that affect the folding process or the stability of the folded structure of proteins. By obstructing the folding process, increasing aggregation or de‐stabilising the native structure, disease‐associated amino acid replacements may cause loss‐of‐function or gain‐of‐function pathologies. For some of this prominent type of mutant proteins, it is possible to improve folding, stabilise the native structure or suppress aggregation using novel approaches. We summarise the mechanistic background for protein misfolding diseases and discuss current concepts for novel therapeutic interventions in this article.Key Concepts:Disease‐associated mutations often jeopardise acquisition of the native structure (folding) of the affected protein or destabilise the native structure.Protein misfolding leads to full or partial loss‐of‐function, because the mutant protein is unable or impaired to fold to the native conformation.Inefficient removal of misfolded proteins resulting in aggregation may cause a gain‐of‐function, if aggregates perturb cellular functions.Protein misfolding may cause loss‐of‐function and gain‐of‐function at the same time with contribution from these two effects being dependent on environmental conditions.The steady state levels and residual function of proteins with mutations impairing folding or stability can be modulated by environmental factors and the condition of protein quality control systems.Pharmacological chaperones support folding, counteract formation of toxic aggregates or stabilise the native structure of mutant proteins.Retuning of the expression of protein quality control components can rescue misfolding of mutant proteins and counteract aggregation.
Parasitic Plants
Authors: Rubiales Diego , Heide‐Jørgensen Henning S 
Published: February 2011

Abstract

Parasitic flowering plants exploit other flowering plants for water and nutrients by specialised structures called haustoria. Part of the haustorium, the intrusive organ, penetrates host tissue to establish contact with the conductive tissue of the host. Parasitic plants occur throughout the world in all types of plant communities except the aquatic. Generally, the parasite weakens the host so it produces fewer flowers and viable seeds or the value as timber is reduced. However, some parasites, mostly annual root parasites belonging to Orobanchaceae, may kill the host and cause considerable economic damage when attacking monocultures in agriculture, and much effort is done to control these harmful parasites.

Key Concepts:

Parasitic plants exploit other plants for water and nutrients by help of haustoria.

Host penetration is a result of pressure combined with enzymatic disintegration of cell membranes (plasmalemma) and host cell walls.

A xylem bridge is the most general anatomical character of the haustorium.

Translocation of water and nutrients is always from host to parasite.

The host range is high for most parasitic plants.

Evolution of the primary haustorium made holoparasitism possible.

A few species of parasitise crops are becoming weeds of huge economic importance.
Regional Influences on Local Species Composition
Authors: Zobel Martin , Szava‐Kovats Robert C , Pärtel Meelis 
Published: February 2011

Abstract

Regional influences on local species composition are considered within the context of ‘species pools’, representing sets of species that are potentially capable of coexisting in a particular community. Accumulating evidence shows that many ecological communities are not saturated with species, indicating that in addition to local biotic interactions such as predation, symbiosis and competition, regional processes such as dispersal, speciation and extinction are the important drivers of local community composition. Although current studies have been unable to reconcile completely two important difficulties – the filtering of species lists and the study of nonindependent variables – it is evident that much of the observed local variation in plant and animal diversity can be attributed to the differing sizes of species pools evolved under particular habitat conditions and to the probabilities with which the species may arrive in particular local communities.

Key Concepts:

Local species composition is the result of complex interactions of small‐scale and regional processes.

Empirical relationships between diversity at local and regional scales provide an indication of the relative roles of local processes (e.g. biotic interactions) and regional processes (e.g. dispersal, speciation) in structuring ecological communities.

Existing evidence suggests that many ecological communities are unsaturated by species and that new species may immigrate to the community by crossing dispersal barriers.

Uncertainty remains with respect to methodology. Estimation of regional species pools lacks a definitive approach; both empirical and theoretical methods exist. The interpretation of local and regional species richness suffers from unresolved statistical controversy.

More case studies are needed to overcome these problems and provide community ecology with further empirical evidence.
Genomic Rearrangements: Mutational Mechanisms
Authors: Chen Jian‐Min 
Published: February 2011

Abstract

Genomic rearrangements involve gross alterations of chromosomes or large chromosomal regions and can take the form of deletions, duplications, insertions, inversions or translocations. The characterisation of a considerable number of rearrangement breakpoints has now been accomplished at the nucleotide sequence level, thereby providing an invaluable resource for the detailed study of the mutational mechanisms which underlie genomic recombination events. At least five categories of mutational mechanism are known to give rise to genomic rearrangements: (i) homologous recombination including nonallelic homologous recombination (NAHR), gene conversion, single strand annealing (SSA) and break‐induced replication (BIR); (ii) nonhomologous end joining (NHEJ); (iii) microhomology‐mediated replication‐dependent recombination (MMRDR); (iv) long interspersed element 1 (LINE‐1 or L1)‐mediated retrotransposition and (v) telomere healing. We compare and contrast the hallmark characteristics of the first three mutational mechanisms and discuss the recent developments with respect to the ratio of deletions to duplications

in vivo

.

Key Concepts:

Genomic rearrangements refer to changes in the genetic linkage relationship of discrete chromosomal fragments, involving deletions, duplications, insertions, inversions or translocations.

At least five categories of mutational mechanism can give rise to genomic rearrangements: homologous recombination, nonhomologous end joining (NHEJ), microhomology‐mediated replication‐dependent recombination (MMRDR), long interspersed element 1 (LINE‐1 or L1)‐mediated retrotransposition, and telomere healing.

Homologous recombination, one of the major pathways for the repair of double‐strand breaks, is mediated through sequences which exhibit considerable homology (generally >200 bp) that presumably serves to stabilise chromosomal mispairing.

Homologous recombination can be further subdivided into four pathways, namely, nonallelic homologous recombination (NAHR), gene conversion, break‐induced replication (BIR) and single‐strand annealing (SSA).

NHEJ involves simple ligation of any two broken DNA ends together. It is the most prominent DNA repair mechanism because it can occur at any time during the cell cycle and does not require a homologous sequence.

Replication‐based models such as serial replication slippage and microhomology‐mediated BIR have been increasingly used to account for the generation of gross genomic rearrangements.

The term ‘MMRDR’ was thought to best define the hallmark characteristics of the aforementioned replication‐based mutational mechanisms as compared with homologous recombination and NHEJ.

A deletion:duplication ratio of between 2 and 3 is likely to represent the best estimate of the relative occurrence of deletion and duplication copy number mutations
in vivo
.
Multistate System Reliability
Authors: Natvig Bent 
Published: February 2011

AbstractOne inherent weakness of traditional reliability theory is that the system and the components are always described just as functioning or failed. The first attempts to replace this by a theory for multistate systems of multistate components were done in the late 1970s. By the mid‐1980s, the basic theory in this area was established. Proper definitions of a multistate monotone system and of multistate coherent systems, and also of minimal path and cut vectors were given. Furthermore, upper and lower bounds for the availabilities and unavailabilities, to any level, in a fixed time interval were arrived at for multistate monotone systems based on corresponding information on the multistate components. These were assumed to be maintained and interdependent. Such bounds are of great interest when trying to predict the performance process of the system, noting that exact expressions are obtainable just for trivial systems. Recently, probabilistic modeling of partial monitoring of components with applications to preventive system maintenance has been extended to multistate monotone systems. A series of applications of multistate reliability theory have been suggested during the past years. This theory enables one in an electrical power generation system, for instance, to let the system state be the amount of power generated, or, in an offshore gas pipeline network, the amount of gas actually delivered.
Gold Catalysis: Alkyl Migration in the Addition of Alcohols to Nitriles
Authors: Ibrahim Nada , Hashmi A. Stephen K. , Rominger Frank 
Published: February 2011

AbstractBenzhydroles and nitriles upon gold‐catalysed conversion deliver symmetrical ethers and/or N‐substituted carboxylic amides. While with most phosphane ligands tested, the dominating product is always the ether, with the trimesitylene ligand the amides are the major products. The reaction conditions are much milder than those reported previously. Mechanistic control experiments with a chiral alcohol prove the intermediacy of carbenium ions, further studies with not readily ionisable alcohols indicate that for the benzhydroles the carbenium ions and gold(I)‐hydroxy complexes are intermediates.
Study on the flame‐retarded poly(methyl methacrylate) by triphenylphosphate and nano‐poly(phenylsilsesquioxane) spheres
Authors: Wang Xinlong , Wu Lianghu , Li Jin 
Published: February 2011

AbstractThe flame‐retarded systems consisting of triphenylphosphate (TPP) and nano‐poly(phenylsilsesquioxane) spheres (nano‐PPSQ) for poly(methyl methacrylate) are reported. The flame‐retarded effects were studied by a cone calorimeter test and thermal gravimetric analysis (TGA). The results show that when a part of TPP was substituted with nano‐PPSQ, the values of the peak heat release rate of the samples are reduced. The burnt resides were analyzed by the scanning electron microscopy, Raman spectra, and X‐ray photoelectron spectroscopy. The results provide evidences that nano‐PPSQ can efficiently promote the formation of more dense and compact charred layers composed of varying amounts of graphite and amorphous carbon. The possible mechanisms were discussed. © 2011 Wiley Periodicals, Inc. Adv Polym Techn 30:33–40, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/adv.20205
Polyester‐based nanocomposite fibers: A preliminary investigation on structure, morphology, and mechanical properties
Authors: Acierno D. , Lavorgna M. , Piscitelli F. , Russo P. , Spena P. 
Published: February 2011

AbstractMelt‐spun fibers produced from poly(butylene terephthalate) and containing very small amounts of multiwall carbon nanotubes (MWNTs) have been investigated. Preliminary studies have been carried out on fibers produced at low draw ratio. The additive contents (≤ 1% by weight) and process conditions for the production of fibers have been optimized to obtain a satisfactory level of MWNTs dispersion for all systems, as confirmed by electron microscopy observations. Structural investigations performed on fibers with varying content and aspect ratio of nanotubes made it possible to relate the observed changes in properties, such as dynamic mechanical behavior and mechanical properties, to the crystalline structure of the polymer in terms of size, main distance between the crystalline lamellae, and orientation. The results have revealed unexpectedly large increase in elongation at break‐in fibres containing MWNTs, even though these exhibited a slight increase in the stiffness of the fibers. This effect has been attributed to structural changes and has also been found to affect the nanotubes' external diameter. © 2011 Wiley Periodicals, Inc. Adv Polym Techn 30:41–50, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/adv.20206
Why do capuchin monkeys urine wash? An experimental test of the sexual communication hypothesis using fMRI
Authors: Phillips Kimberley A. , Buzzell Courtney A. , Holder Nicholas , Sherwood Chet C. 
Published: February 2011

AbstractUrine washing (UW) consists of depositing urine on the hands and vigorously rubbing the body. As urine contains chemical and pheromonal cues, UW may convey socially relevant information. Although ritualized UW is observed in many New World primates, including capuchin monkeys, the functional significance of UW remains unclear. In this experiment, we investigated the social signaling hypothesis of UW. Specifically, we hypothesized that UW by males conveys socially relevant signals that females can detect. We used functional magnetic resonance imaging (fMRI) to test whether adult female capuchins show differential brain activation in response to adult male and juvenile male capuchin urine. We expected to see changes in activation of structures involved in olfactory processing, including the piriform cortex, medial preoptic and anterior hypothesis, orbitofrontal cortex, hippocampus, and cerebellum. Data were acquired from four adult female capuchin monkeys. Presentations of odor stimuli (obtained from unfamiliar males) were made during fMRI acquisition using a standard ON‐OFF design. All fMRI data were spatially normalized to a template and analyzed using the FMRI Expert Analysis Tool Version 5.98, part of the FMRIB's Software Library (www.fmrib.ox.ac.uk/fsl). Whole brain analyses revealed significant activations in the inferior temporal cortex, parahippocampal gyrus, precuneus, hippocampus, pulvinar, and cerebellum when females were presented with the adult male urine. Notably, significantly greater signal activation was observed in several regions associated with olfactory processing, when subjects were presented with adult male urine as compared with urine from juvenile males. Our results indicate that UW serves a social communicative function in capuchins, providing support for the sexual signaling hypothesis. Am. J. Primatol. 73:578‐584, 2011. © 2011 Wiley‐Liss, Inc.
Sorption of textile dye from aqueous solution by macroporous amino‐functionalized copolymer
Authors: Sandić Zvjezdana P. , Nastasović Aleksandra B. , Jović‐Jovičić Nataša P. , Milutinović‐Nikolić Aleksandra D. , Jovanović Dušan M. 
Published: February 2011

AbstractMacroporous poly(glycidyl methacrylate‐co‐ethylene glycol dimethacrylate) (PGME) was synthesized by suspension copolymerization and functionalized with diethylene triamine (PGME‐deta). The effect of pH, contact time, and sorbent mass on sorption efficiency of initial and functionalized copolymer sample for removal of Acid Orange 10 dye from aqueous solutions was studied. No dye was sorbed by nonfunctionalized copolymer, indicating that sorption of Acid Orange 10 by PGME‐deta is specific, through amino groups. The isotherm data are best fitted by Langmuir model, indicating homogeneous distribution of active sites in PGME‐deta as well as monolayer sorption. Sorption kinetics study showed that the sorption of Acid Orange 10 by PGME‐deta obeys the pseudo‐second‐order kinetic model. It was shown that PGME‐deta selectively sorbs Acid Orange 10 from binary solution with Bezaktiv Rot reactive dye. The comparison of sorption characteristics of PGME‐deta with activated carbon showed that this functionalized copolymer might be used as an alternative sorbent for textile dyes. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
The pH‐responsive cycloterpolymers of diallyldimethylammonium chloride, 3‐(N,N‐diallylammonio)propanesulfonate, and sulfur dioxide
Authors: Abu‐Thabit N. Y. , Al‐Muallem H. A. , Ali S. Asrof 
Published: February 2011

AbstractThe cycloterpolymerizations of diallyldimethylammonium chloride, 3‐(N,N‐diallylammonio)propanesulfonate, and sulfur dioxide afforded a series of pH‐responsive cycloterpolymers in excellent yields. The solution properties of these ionic polymers were controlled by the composition of the monomeric units; exhibiting dominance either in polyzwitterionic or cationic character. The unquenched valency of nitrogen in the monomeric units of the sulfobetaine zwitterions has permitted these cationic/zwitterionic polymers to be converted into a series of polyampholytes with a charge asymmetry arising out of excess of either the cationic or anionic centers. The water‐solubility of these polymers, upon low‐ and high‐salt (NaCl) additions has been investigated to provide critical solution concentrations to promote water‐insolubility and ‐solubility. A series of associating polymers of the above two monomers and SO2 with a hydrophobic incorporation of 3–7 mol % of diallyloctadecylammonium chloride has also been synthesized. The solubility and viscosity of the hydrophobically modified polymers in the polyampholytic form were increased considerably in the presence of anionic surfactant sodium dodecyl sulfate. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Degradation of the crocodile population in the Olifants River Gorge of Kruger National Park, South Africa
Authors: Ferreira Sam M. , Pienaar Danie 
Published: February 2011

Abstract

Top predators such as crocodiles often reflect ecosystem degradation. The recent spate of close to 200 Nile crocodile deaths may reflect the ecosystem state of the Olifants–Letaba River system in the Kruger National Park. This paper investigates whether the crocodile deaths were indeed the consequence of a rare and perhaps acute event given the variability in annual population growth rates of crocodilians.
Spotlight‐ and helicopter‐based surveys designed to correct for availability and detectability bias were used to estimate population sizes of crocodiles from 2008 to 2010 in and around the Olifants River Gorge, the focal area of crocodile deaths.
Correction factors derived from individually observed crocodiles for both spotlight‐ and helicopter‐based counts were lower than those typically used for Nile crocodiles as well as other crocodile species. Even so, corrected spotlight‐ and helicopter‐based estimates were comparable and the number of crocodiles in the focal study area declined significantly from 780 (95% CI: 637–1222) to between 460 (spotlight estimate, 95% CI 375–665) and 505 (aerial estimate, 95% CI: 559–1746) during the period of crocodile deaths. The average annual decline of 35% was at the lower end of the distribution of annual population growth rates across the rivers of Kruger National Park.
The crocodile deaths reflect a possible rare event that suggests a degraded crocodile population, possibly the consequences of broad‐scale cascades of environmental deterioration of the Olifants–Letaba River system.
Even so, the potential risk of local demise of the population in the focal study area in the short term may be diminished through evolutionary, demographic and spatial resilience inherent within crocodiles that can accommodate the as yet unknown disease dynamics of pansteatitis. Copyright © 2011 John Wiley & Sons, Ltd.
S100A8 enhances osteoclastic bone resorption in vitro through activation of Toll‐like receptor 4: Implications for bone destruction in murine antigen‐induced arthritis
Authors: Grevers Lilyanne C. , de Vries Teun J. , Vogl Thomas , Abdollahi‐Roodsaz Shahla , Sloetjes Annet W. , Leenen Pieter J. M. , Roth Johannes , Everts Vincent , van den Berg Wim B. , van Lent Peter L. E. M. 
Published: February 2011

AbstractObjectiveRheumatoid arthritis, which is associated with elevated levels of S100A8 and S100A9, is characterized by severe bone erosions caused by enhanced osteoclast formation and activity. The aim of the present study was to investigate the role of S100A8 and S100A9 in osteoclastic bone destruction in murine antigen‐induced arthritis (AIA).MethodsBone destruction was analyzed in the arthritic knee joints of S100A9‐deficient mice in which S100A8 protein expression was also lacking, and in wild‐type (WT) controls. Osteoclast precursors from S100A9‐deficient and WT mice were differentiated into osteoclasts in vitro. Additionally, precursors were stimulated with S100A8, S100A9, or S100A8/A9 during osteoclastogenesis. Receptor involvement was investigated using an anti–receptor for advanced glycation end products (anti‐RAGE)–blocking antibody, soluble RAGE, or Toll‐like receptor 4 (TLR‐4)–deficient osteoclast precursors. The formation of osteoclasts and actin rings, the regulation of osteoclast markers, and bone resorption were analyzed.ResultsBone erosions and cathepsin K staining were significantly suppressed in S100A9‐deficient mice after AIA induction. However, osteoclast precursors from S100A9‐deficient mice developed normally into functional osteoclasts, which excludes a role for intrinsic S100A8/A9. In contrast to the results observed with S100A9 and S100A8/A9, the addition of S100A8 during osteoclastogenesis resulted in stimulation of osteoclast formation in conjunction with enhanced actin ring formation and increased bone resorption. Analysis of the putative receptor for S100A8 in osteoclastogenesis revealed that osteoclast differentiation and function could not be inhibited by blocking RAGE, whereas the increase in osteoclast numbers and enhanced bone resorption were completely abrogated using TLR‐4–deficient osteoclast precursors.ConclusionThese results demonstrate that S100A8 stimulated osteoclast formation and activity and suggest that both S100A8 and TLR‐4 are important factors in mediating osteoclastic bone destruction in experimental arthritis.
Design and stability analysis of a variable structure adaptive backstepping controller
Authors: Queiroz Kurios , Araujo Aldayr , Dias Samaherni 
Published: February 2011

AbstractThis paper presents the design and stability analysis of a Variable Structure Adaptive Backstepping Controller (VS‐ABC) for linear plants with relative degree one, using only input/output measurements. Instead of traditional integral adaptive laws for estimating the plant parameters, switching laws are proposed to increase robustness to parametric uncertainties and disturbances, as well as to improve transient response. Moreover, the controller design is more intuitive when compared with the original adaptive backstepping controller, since the relay amplitudes are related to the plant nominal parameters and their respective uncertainties. Simplified algorithm versions are also presented, named Compact and Relay VS‐ABC, which reduce the practical implementation complexity, and encourage applications in industrial environments.Copyright © 2011 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society