bluuebunny/crossref_metadata_2025 huggingface dataset:
An investigation of melt rheology and thermal stability of poly(lactic acid)/ poly(butylene succinate) nanocomposites
Authors: Bhatia Amita , Gupta Rahul K. , Bhattacharya Sati N. , Choi H. J.
Published: July 2009

A systematic investigation of the rheological and thermal properties of nanocomposites prepared with poly(lactic acid) (PLA), poly(butylene succinate) (PBS), and organically modified layered silicate was carried out. PLA/PBS/Cloisite 30BX (organically modified MMT) clay nanocomposites were prepared by using simple melt extrusion process. Composition of PLA and PBS polymers were fixed at a ratio of 80 to 20 by wt % for all the nanocomposites. Rheological investigations showed that high clay (> 3 wt %) contents strongly improved the viscoelastic behavior of the nanocomposites. Percolation threshold region was attained between 3 and 5 wt % of clay loadings. With the addition of clay content for these nanocomposites, liquid‐like behavior of PLA/PBS blend gradually changed to solid‐like behavior as shown by dynamic rheology. Steady shear showed that shear viscosity for the nanocomposites decreased with increasing shear rates, exhibiting shear‐thinning non‐Newtonian behavior. At higher clay concentrations, pseudo‐plastic behavior was dominant, whereas pure blend showed almost Newtonian behavior. Thermogravimetric analysis revealed that both initial degradation temperature (at a 2% weight loss) and activation energy of thermal decomposition nanocomposite containing 3 wt % of C30BX were superior to those of other nanocomposites as well as to those of PLA/PBS blend. Nanocomposite having 1 wt % of C30BX did not achieve expected level of thermal stability due to the thermal instability of the surfactant present in the organoclay. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Fundamental studies of a new series of anion exchange membranes: Membranes prepared from bromomethylated poly(2,6‐dimethyl‐1,4‐phenylene oxide) and 4‐vinylpyridine
Authors: Li Yuan , Xu Tongwen
Published: July 2009

A series of anion exchange membranes with pyridinium groups were prepared by aminating 100% bromomethylated poly(2,6‐dimethyl‐1,4‐phenylene oxide) with 4‐vinylpyridine. These membranes exhibited higher ion exchange capacity, lower water uptake, lower area resistance, and better thermal stabilities than the membranes prepared from pyridine. Trimethylamine was used for further amination, but it did not enhance the membrane's permselectivity for fluoride, chloride, bromide, iodide, hydroxyl, nitrate, nitrite, or thiocyanate anions. Accordingly, 4‐vinylpyridine was the better aminating agent to enhance the permselectivity of membranes for some monovalent anions. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Preparation and characterization of high char yield polybenzoxazine/polyarylacetylene blends for resin‐transfer molding
Authors: Qi Huimin , Pan Guangyan , Yin Lian , Zhuang Yuanqi , Huang Farong , Du Lei
Published: July 2009

Benzoxazine precursors (BOZP), 6,6′‐bis(2,3‐dihydro‐3‐(3‐ethynylphenyl)‐4H‐1,3‐ benzoxazinyl)ketone and 6,6′‐bis(2,3‐dihydro‐3‐(3‐ethynylphenyl)‐4H‐1,3‐benzoxazinyl)ether were synthesized and characterized by Proton nuclear magnetic resonace (1H‐NMR) and Fourier transform infrared spectroscopy (FTIR). The polyarylacetylene (PAA) was synthesized through thermal polymerization of diethynylbenzene, and characterized by 1H‐NMR, FTIR, and Differential Scanning Calorimetry (DSC). The BOZP/PAA blends were prepared with different contents of PAA, and their viscosity was measured using NDJ‐79 rotating visometer. The curing behavior of BOZP/PAA blends was characterized by DSC. The thermal stability of cured BOZP/PAA blends was studied using Thermogravimetric Analysis, the results show char yield at 800°C was in the range of 78–84%. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Interpreting informational cues: An explorative study on information use among prospective homebuyers
Authors: Savolainen Reijo
Published: July 2009

This article elaborates the picture of information use from the perspective of interpreting informational cues about the attributes of entities. It is assumed that such activity draws on cognitive mechanisms that are employed as the constituents of diverse interpretation approaches to informational cues. The empirical data of the study were gathered by means of think aloud method from 16 prospective homebuyers in 2008. The participants interpreted informational cues available in announcements published in a printed housing listing issue and a Web‐based information system serving the needs of prospective homebuyers. The data were examined by means of qualitative content analysis. By drawing on the findings of Zhang and her associates, the study revealed 7 cognitive mechanisms: identification of key attributes, specification, evaluation, comparison by similarity, comparison by differentiation, explanation, and conclusion. Three major approaches employed in the interpetation of informational cues were identified. The descriptive‐evaluative approach draws on the identification and evaluation of individual attributes of an entity. The comparative approach is more sophisticated because it is based on the evaluation of the attributes by their perceived similarity or differentiation. Finally, the explanatory approach draws on the identification of attributes with causal potential.
Addressing gaps in knowledge while reading
Authors: Jordan Chris , Watters Carolyn
Published: July 2009

Reading is a common everyday activity for most of us. In this article, we examine the potential for using Wikipedia to fill in the gaps in one's own knowledge that may be encountered while reading. If gaps are encountered frequently while reading, then this may detract from the reader's final understanding of the given document. Our goal is to increase access to explanatory text for readers by retrieving a single Wikipedia article that is related to a text passage that has been highlighted. This approach differs from traditional search methods where the users formulate search queries and review lists of possibly relevant results. This explicit search activity can be disruptive to reading. Our approach is to minimize the user interaction involved in finding related information by removing explicit query formulation and providing a single relevant result. To evaluate the feasibility of this approach, we first examined the effectiveness of three contextual algorithms for retrieval. To evaluate the effectiveness for readers, we then developed a functional prototype that uses the text of the abstract being read as context and retrieves a single relevant Wikipedia article in response to a passage the user has highlighted. We conducted a small user study where participants were allowed to use the prototype while reading abstracts. The results from this initial study indicate that users found the prototype easy to use and that using the prototype significantly improved their stated understanding and confidence in that understanding of the academic abstracts they read.
Autism spectrum disorders in relation to parental occupation in technical fields
Authors: Windham Gayle C. , Fessel Karen , Grether Judith K.
Published: July 2009

A previous study reported that fathers of children with autism spectrum disorders (ASD) were more likely to work as engineers, requiring “systemizing skills,” and suggesting a distinct phenotype, but alternatively this may have been related to selection biases. We conducted a population‐based study to explore whether fathers, or mothers, of children with ASD are over‐represented in fields requiring highly technical skills. Subjects included 284 children with ASD and 659 gender‐matched controls, born in 1994 in the San Francisco Bay Area. Parental occupation and industry were abstracted verbatim from birth certificates. Engineering, computer programming, and science were examined as highly technical occupations. To limit bias by parental socio‐economic status, we selected a referent group of occupations that seemed professionally similar but of a less technical nature. Odds ratios (ORs) and 95% confidence intervals (CI) were calculated by logistic regression, adjusting for parental age, education, and child race. Mothers of cases were somewhat more likely to work in hi‐tech occupations (6.7%) than mothers of controls (4.0%, P=0.07), but little difference was observed among fathers, nor for engineering separately. Compared to parents in other “white collar” occupations, the adjusted OR for highly technical occupations among mothers was 2.5 (95% CI: 1.2–5.3) and among fathers was 1.3 (95% CI: 0.79–2.1), with no evidence of a joint effect observed. Our results regarding maternal occupation in technical fields being associated with ASD in offspring suggest further study to distinguish parental occupation as a phenotypic marker of genetic loading vs. other social or exposure factors.
scFv‐based fluorogen activating proteins and variable domain inhibitors as fluorescent biosensor platforms
Authors: Falco Crystal N. , Dykstra Kaitlyn M. , Yates Bradley P. , Berget Peter B.
Published: July 2009

Single chain antibodies (scFvs) are engineered proteins composed of IgG variable heavy (VH) and variable light (VL) domains tethered together by a flexible peptide linker. We have characterized the individual VH or VL domain activities of several scFvs isolated from a yeast surface‐display library for their ability to bind environmentally sensitive fluorogenic dyes causing them to fluoresce. For many of the scFvs, both VH and VL domains are required for dye binding and fluorescence. The analysis of other scFvs, however, revealed that either the VH or the VL domain alone is sufficient to cause the fluorogenic dye activation. Furthermore, the inactive complementary domains in the original scFvs either contribute nothing to, or actually inhibit the activity of these active single domains. We have explored the interactions between active variable domains and inactive complementary domains by extensive variable domain swapping through in vitro gene manipulations to create hybrid scFvs. In this study, we demonstrate that significant alteration of the fluorogenic dye activation by the active VH or VL domains can occur by partnering with different VH or VL complementary domains in the scFv format. Hybrid scFvs can be generated that have fluorogen‐activating domains that are completely inhibited by interactions with other domains. Such hybrid scFvs are excellent platforms for the development of several types of genetically encoded, fluorescence‐generating biosensors.
Cloning and overexpression of a thermostable signal peptide peptidase (SppA) from Thermoplasma volcanium GSS1 in E. coli
Authors: Kocabıyık Semra , Demirok Burçak
Published: July 2009

On page 1064, 5 lines from the bottom, it states “Lys is found at position 461 (Ec umbering) instead of Ala [28, 29].”

The correct sentence should be “However, in the E.coli enzyme, instead of Lys at position 461 (Ec numbering), there is Ala‐461 [28, 29].”
Improved triglyceride transesterification by circular permuted Candida antarctica lipase B
Authors: Yu Ying , Lutz Stefan
Published: July 2009

Lipases represent a versatile class of biocatalysts with numerous potential applications in industry including the production of biodiesel via enzyme‐catalyzed transesterification. In this article, we have investigated the performance of cp283, a variant of Candida antarctica lipase B (CALB) engineered by circular permutation, with a series of esters, as well as pure and complex triglycerides. In comparison with wild‐type CALB, the permutated enzyme showed consistently higher catalytic activity (2.6‐ to 9‐fold) for trans and interesterification of the different substrates with 1‐butanol and ethyl acetate as acyl acceptors. Differences in the observed rates for wild‐type CALB and cp283 are believe to be related to changes in the rate‐determining step of the catalytic cycle as a result of circular permutation. Biotechnol. Bioeng. 2010;105: 44–50. © 2009 Wiley Periodicals, Inc.
Improvement of low‐temperature caseinolytic activity of a thermophilic subtilase by directed evolution and site‐directed mutagenesis
Authors: Zhong Chuan‐Qi , Song Shengli , Fang Nan , Liang Xiaoliang , Zhu Hui , Tang Xiao‐Feng , Tang Bing
Published: July 2009

By directed evolution and subsequent site‐directed mutagenesis, cold‐adapted variants of WF146 protease, a thermophilic subtilase, have been successfully engineered. A four‐amino acid substitution variant RTN29 displayed a sixfold increase in caseinolytic activity in the temperature range of 15–25°C, a down‐shift of optimum temperature by ∼15°C, as well as a decrease in thermostability, indicating it follows the general principle of trade‐off between activity and stability. Nevertheless, to some extent RTN29 remained its thermophilic nature, and no loss of activity was observed after heat‐treatment at 60°C for 2 h. Notably, RTN29 exhibited a lower hydrolytic activity toward suc‐AAPF‐pNA, due to an increase in Km and a decrease in kcat, in contrast to other artificially cold‐adapted subtilases with increased low‐temperature activity toward small synthetic substrates. All mutations (S100P, G108S, D114G, M137T, T153A, and S246N) identified in the cold‐adapted variants occurred within or near the substrate‐binding region. None of these mutations, however, match the corresponding sites in naturally psychrophilic and other artificially cold‐adapted subtilases, implying there are multiple routes to cold adaptation. Homology modeling and structural analysis demonstrated that these mutations led to an increase in mobility of substrate‐binding region and a modulation of substrate specificity, which seemed to account for the improvement of the enzyme's catalytic activity toward macromolecular substrates at lower temperatures. Our study may provide valuable information needed to develop enzymes coupling high stability and high low‐temperature activity, which are highly desired for industrial use. Biotechnol. Bioeng. 2009; 104: 862–870. © 2009 Wiley Periodicals, Inc.
Optimization of pH and nitrogen for enhanced hydrogen production by Synechocystis sp. PCC 6803 via statistical and machine learning methods
Authors: Burrows Elizabeth H. , Wong Weng‐Keen , Fern Xiaoli , Chaplen Frank W. R. , Ely Roger L.
Published: July 2009

The nitrogen (N) concentration and pH of culture media were optimized for increased fermentative hydrogen (H2) production from the cyanobacterium, Synechocystis sp. PCC 6803. The optimization was conducted using two procedures, response surface methodology (RSM), which is commonly used, and a memory‐based machine learning algorithm, Q2, which has not been used previously in biotechnology applications. Both RSM and Q2 were successful in predicting optimum conditions that yielded higher H2 than the media reported by Burrows et al., Int J Hydrogen Energy. 2008;33:6092–6099 optimized for N, S, and C (called EHB‐1 media hereafter), which itself yielded almost 150 times more H2 than Synechocystis sp. PCC 6803 grown on sulfer‐free BG‐11 media. RSM predicted an optimum N concentration of 0.63 mM and pH of 7.77, which yielded 1.70 times more H2 than EHB‐1 media when normalized to chlorophyll concentration (0.68 ± 0.43 μmol H2 mg Chl−1 h−1) and 1.35 times more when normalized to optical density (1.62 ± 0.09 nmol H2 OD730−1 h−1). Q2 predicted an optimum of 0.36 mM N and pH of 7.88, which yielded 1.94 and 1.27 times more H2 than EHB‐1 media when normalized to chlorophyll concentration (0.77 ± 0.44 μmol H2 mg Chl−1 h−1) and optical density (1.53 ± 0.07 nmol H2 OD730−1 h−1), respectively. Both optimization methods have unique benefits and drawbacks that are identified and discussed in this study. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009
Invariability of central metabolic flux distribution in Shewanella oneidensis MR‐1 under environmental or genetic perturbations
Authors: Tang Yinjie J. , Martin Hector Garcia , Deutschbauer Adam , Feng Xueyang , Huang Rick , Llora Xavier , Arkin Adam , Keasling Jay D.
Published: July 2009

An environmentally important bacterium with versatile respiration, Shewanella oneidensis MR‐1, displayed significantly different growth rates under three culture conditions: minimal medium (doubling time ∼3 h), salt stressed minimal medium (doubling time ∼6 h), and minimal medium with amino acid supplementation (doubling time ∼1.5 h). 13C‐based metabolic flux analysis indicated that fluxes of central metabolic reactions remained relatively constant under the three growth conditions, which is in stark contrast to the reported significant changes in the transcript and metabolite profiles under various growth conditions. Furthermore, 10 transposon mutants of S. oneidensis MR‐1 were randomly chosen from a transposon library and their flux distributions through central metabolic pathways were revealed to be identical, even though such mutational processes altered the secondary metabolism, for example, glycine and C1 (5,10‐Me‐THF) metabolism. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009
An efficient algorithm for Parafac with uncorrelated mode‐A components applied to large I × J × K data sets with I >> JK
Authors: Kiers Henk A. L. , Harshman Richard A.
Published: July 2009

Harshman and Lundy (Comput. Stat. Data Anal. 1994; 18: 39–72) described an option in the Parafac algorithm for constraining one or more component matrices to have uncorrelated columns. In cases where an algorithm using this constraint is to be applied to a three‐way array that has too many entries in one mode, the algorithm is computationally impractical. The present paper describes two modifications of their algorithm to handle the multiplications involving the large mode efficiently for cases where the product of the sizes of the other two modes is smaller than that of the larger mode. By means of a simulation study, it is demonstrated that these procedures (which are similarly efficient) are much more efficient than the original algorithm. Copyright © 2009 John Wiley & Sons, Ltd.
A case study illustrating traps, pitfalls and concerns for the hypnodontist
Authors: Filo Gabor
Published: July 2009

This case study is about hypnosis for intractable pain in the case of a patient who had trigeminal neuralgia, which through medical intervention had become anaesthesia dolorosa. The study will address the demand characteristics set up by the patient. Inherent in the demands were pitfalls and traps that ultimately resulted in a pyrrhic victory. This case illustrates the need to know the limits for the hypnodontist: of their jurisdictionally permitted scope of practice; their own abilities; whose goals are being met by the intervention; and what outcomes define success for the patient and the hypnodontist. Copyright © 2009 British Society of Experimental & Clinical Hypnosis. Published by John Wiley & Sons, Ltd.
Noncovalent Synthesis of Protein Dendrimers
Authors: Lempens Edith H. M. , van Baal Ingrid , van Dongen Joost L. J. , Hackeng Tilman M. , Merkx Maarten , Meijer E. W.
Published: July 2009

The covalent synthesis of complex biomolecular systems such as multivalent protein dendrimers often proceeds with low efficiency, thereby making alternative strategies based on noncovalent chemistry of high interest. Here, the synthesis of protein dendrimers using a strong but noncovalent interaction between a peptide and complementary protein is proposed as an efficient strategy to arrive at dendrimers fully functionalized with protein domains. The association of S‐peptide to S‐protein results in the formation of an active enzyme (ribonuclease S) and therefore serves as an ideal system to explore this synthetic approach. Native chemical ligation was used to couple four S‐peptides by means of their C‐terminal thioester to a cysteine‐functionalized dendritic scaffold, thus yielding a tetravalent S‐peptide wedge. A fully functional ribonuclease S tetramer was prepared by addition of four equivalents of S‐protein. Biophysical techniques (isothermal titration calorimetry (ITC), surface plasmon resonance (SPR), and mass spectrometry) and an enzymatic activity assay were used to verify the formation of the multivalent complex. The noncovalent synthetic strategy presented here provides access to well‐defined, dynamic, semisynthetic protein assemblies in high yield and is therefore of interest to the field of nanomedicine as well as biomaterials.
Transition‐Metal Complexes [(PMe3)2Cl2M(E)] and [(PMe3)2(CO)2M(E)] with Naked Group 14 Atoms (E=C–Sn) as Ligands; Part 2: Complexation with W(CO)5
Authors: Parameswaran Pattiyil , Frenking Gernot
Published: July 2009

Density functional calculations at the BP86/TZ2P level were carried out to understand the ligand properties of the 16‐valence‐electron(VE) Group 14 complexes [(PMe3)2Cl2M(E)] (1ME) and the 18‐VE Group 14 complexes [(PMe3)2(CO)2M(E)] (2ME; M=Fe, Ru, Os; E=C, Si, Ge, Sn) in complexation with W(CO)5. Calculations were also carried out for the complexes (CO)5W–EO. The complexes [(PMe3)2Cl2M(E)] and [(PMe3)2(CO)2M(E)] bind strongly to W(CO)5 yielding the adducts 1ME–W(CO)5 and 2ME–W(CO)5, which have C2v equilibrium geometries. The bond strengths of the heavier Group 14 ligands 1ME (E=Si–Sn) are uniformly larger, by about 6–7 kcal mol−1, than those of the respective EO ligand in (CO)5W‐EO, while the carbon complexes 1MC–W(CO)5 have comparable bond dissociation energies (BDE) to CO. The heavier 18‐VE ligands 2ME (E=Si–Sn) are about 23–25 kcal mol−1 more strongly bonded than the associated EO ligand, while the BDE of 2MC is about 17–21 kcal mol−1 larger than that of CO. Analysis of the bonding with an energy‐decomposition scheme reveals that 1ME is isolobal with EO and that the nature of the bonding in 1ME–W(CO)5 is very similar to that in (CO)5W–EO. The ligands 1ME are slightly weaker π acceptors than EO while the π‐acceptor strength of 2ME is even lower.
Asymmetrical Fluorene[2,3‐b]benzo[d]thiophene Derivatives: Synthesis, Solid‐State Structures, and Application in Solution‐Processable Organic Light‐Emitting Diodes
Authors: Du Chunyan , Ye Shanghui , Chen Jianming , Guo Yunlong , Liu Yunqi , Lu Kun , Liu Ying , Qi Ting , Gao Xike , Shuai Zhigang , Yu Gui
Published: July 2009

A series of novel asymmetrical fused compounds containing the backbone of fluorene[2,3‐b]benzo[d]thiophene (FBT) were effectively synthesized and fully characterized. Single‐crystal X‐ray studies demonstrated that the length of the substituent side chains greatly affects the solid‐state packing of the obtained fused compounds. DFT, photophysical, and electrochemical studies all showed that the FBTs have large band gaps, low‐lying HOMO energy levels, and therefore good stability toward oxidation. Moreover, the substituents strongly influence the fluorescence properties of the resulting FBT derivatives. The di‐n‐hexyl compound exhibits intense fluorescence in solution with the highest quantum yield of up to 91 %. Solution‐processed green phosphorescent organic light‐emitting diodes with the di‐n‐butyl derivative as the host material exhibited a maximum brightness of 14 185 cd m−2 and a luminescence efficiency of 12 cd A−1.
Photochemistry of Cyclic Trisilanes: “Spring‐Loaded” Precursors to Methylphenylsilylene
Authors: Moiseev Andrey G. , Coulais Eugénie , Leigh William J.
Published: July 2009

Two new cyclic trisilanes containing a SiMePh moiety in the central position have been synthesized, and their photochemistries studied by steady‐state and laser flash photolysis methods. The yield of the transient silylene SiMePh increases at the expense of that of the corresponding cyclic silene derivative (formed by photochemical 1,3‐silyl migration into the phenyl ring) as the ring size is decreased from 7 to 6, facilitating the direct detection of the silylene by laser flash photolysis. The UV/Vis spectrum of SiMePh in hexanes solution (λmax=270, 505 nm) and absolute rate constants for its reaction with methanol, triethylsilane, a terminal alkene, alkyne, and two aliphatic dienes at 25 °C are reported.
Striking Reactivity of a Stable, Zwitterionic Silylene Towards Substituted Diazomethanes, Azides, and Isocyanides
Authors: Xiong Yun , Yao Shenglai , Driess Matthias
Published: July 2009

The reactivity of the zwitterionic N‐heterocyclic silylene (NHS) LSi: 1 (L=ArNC(Me)CHC(CH2)NAr, Ar=2,6‐iPr2C6H3), towards diphenyldiazomethane (Ph2CN2), trimethylsilyl azide (Me3SiN3), and cyclohexyl isocyanide (C6H11NC) is reported. The addition of Ph2CN2 to 1 leads to the diiminylsilane LSi(NCPh2)2 2 (80 % yield), whereas the treatment of 1 with Me3SiN3 gives the spirobicyclic silatetrazoline LSi(NNSiMe3)2 3 (67 % yield), and addition of C6H11NC gives the silyl cyanide LSi(R)CN (R=cyclohexyl) 4 (32 % yield) along with the unexpected azasilacyclobutane 5 (41 % yield). The novel compounds were fully characterized by 1H, 13C, and 29Si NMR spectroscopy, ESIMS, elemental analysis, and single‐crystal X‐ray diffraction.
Combination of Variant and Microvascular Angina
Authors: Infusino Fabio , Lanza Gaetano A. , Sestito Alfonso , Sgueglia Gregory A. , Crea Filippo , Maseri Attilio
Published: July 2009

Prinzmetal's variant angina (VA) and cardiac syndrome X (CSX) are two distinct, usually easily recognizable, forms of angina syndromes, caused by epicardial spasm, usually responsible for transient transmural myocardial ischemia at rest and by coronary microvascular dysfunction (CMVD), usually responsible for effort induced subendocardial ischemia, respectively. In this article we report clinical evidence in three patients of the simultaneous occurrence of angina episodes typical of both VA and CSX, suggesting that common pathogenetic factors may be responsible for clinical manifestations both of functional macrovascular and microvascular coronary artery abnormalities in some angina patients. Copyright © 2009 Wiley Periodicals, Inc.
The origins and present status of the radio wave controversy in NMR
Authors: Hoult D.I.
Published: July 2009

The origins, history, and present status of the controversy surrounding a quantum description of the NMR signal as being due to radio waves are traced. With the Principle of Relativity and Coulomb's Law as formal starting points and the minimum of mathematics needed for understanding, the derivation of a classical electromagnetic theory of signal reception is first given. The agreement between that classical theory and a recent NMR experiment is then presented, leading to proof that, except for the highest field imaging experiments, there is no significant contribution of radio waves to the signal. Attention is drawn to the very different properties of the near and far energy, momenta, and fields inherent in the derivation. The role of the Correspondence Principle in formulating a quantum description is then emphasized and it is shown that the standard NMR interpretation of Dicke's theory of coherent spontaneous emission—that the latter is responsible for the NMR signal—cannot be correct. Finally, the author speculates on some of the intriguing relationships found in the classical electrodynamics of NMR signal reception and attempts to relate them to a common quantum electrodynamic precept of near field interaction: that the free induction decay voltage present at the terminals of an open‐circuit receiving coil is based on an exchange of virtual photons between the nuclei in a sample and the free electrons in a receiving coil. © 2009 Crown in the right of Canada. Concepts Magn Reson Part A 34A: 193–216, 2009.
Morphology of retinal ganglion cells in the ferret (Mustela putorius furo)
Authors: Isayama Tomoki , O'Brien Brendan J. , Ugalde Irma , Muller Jay F. , Frenz Aaron , Aurora Vikas , Tsiaras William , Berson David M.
Published: July 2009

The ferret is the premiere mammalian model of retinal and visual system development, but the spectrum and properties of its retinal ganglion cells are less well understood than in another member of the Carnivora, the domestic cat. Here, we have extensively surveyed the dendritic architecture of ferret ganglion cells and report that the classification scheme previously developed for cat ganglion cells can be applied with few modifications to the ferret retina. We confirm the presence of alpha and beta cells in ferret retina, which are very similar to those in cat retina. Both cell types exhibited an increase in dendritic field size with distance from the area centralis (eccentricity) and with distance from the visual streak. Both alpha and beta cell populations existed as two subtypes whose dendrites stratified mainly in sublamina a or b of the inner plexiform layer. Six additional morphological types of ganglion cells were identified: four monostratified cell types (delta, epsilon, zeta, and eta) and two bistratified types (theta and iota). These types closely resembled their counterparts in the cat in terms of form, relative field size, and stratification. Our data indicate that, among carnivore species, the retinal ganglion cells resemble one another closely and that the ferret is a useful model for studies of the ontogenetic differentiation of ganglion cell types. J. Comp. Neurol. 517:459–480, 2009. © 2009 Wiley‐Liss, Inc.
Afferent and efferent projections of the central caudal nidopallium in the pigeon (Columba livia)
Authors: Atoji Yasuro , Wild J. Martin
Published: July 2009

The central caudal nidopallium (NCC) is a large subdivision of the nidopallium in the pigeon brain, but its connectional anatomy is unknown. Here, we examined the connections of NCC by using tract‐tracing methods. Injections of cholera toxin B‐chain (CTB) in NCC labeled many neurons within NCC. Outside NCC, many labeled neurons were found in the dorsal intermediate mesopallium and medialmost part of the medial intermediate nidopallium, with a few in the intermediate (AI) and medial (AM) arcopallium. In the thalamus, labeled neurons were located in the subrotundal nucleus, the shell region of nucleus ovoidalis, and the caudal part of the dorsolateral posterior thalamic nucleus. Injections of biotinylated dextran amine (BDA) in NCC labeled many fibers running rostrocaudally within NCC. Some of these terminated in the dorsal intermediate mesopallium, but the size of the terminal field was smaller than the region of the dorsal intermediate mesopallium that provided the projection to NCC. NCC sent numerous efferents to AI and AM but few to the thalamus. In contrast, after CTB injections in the dorsal intermediate mesopallium, a few neurons were labeled in NCC, but, after BDA injections in the dorsal intermediate mesopallium, large numbers of labeled fibers were seen to project widely throughout NCC. These findings indicate that the flow of information is predominantly from the dorsal intermediate mesopallium to NCC and from there to the arcopallium (AI and AM). The arcopallial outflow to the medial hypothalamus could imply that NCC is involved in neuroendocrine and autonomic functions and is limbic in nature. J. Comp. Neurol. 517:350–370, 2009. © 2009 Wiley‐Liss, Inc.
Purkinje cell compartmentation of the cerebellum of microchiropteran bats
Authors: Kim Ji‐Young , Marzban Hassan , Chung Seung‐Hyuk , Watanabe Masahiko , Eisenman Leonard M. , Hawkes Richard
Published: July 2009

Transverse boundaries divide the mammalian cerebellar cortex into transverse zones, and within each zone the cortex is further subdivided into a symmetrical array of parasagittal stripes. This topography is highly conserved across the Mammalia. Bats have a remarkable cerebellum with presumed adaptations to flight and to echolocation, but nothing is known of its compartmentation. We have therefore used two Purkinje cell compartmentation antigens, zebrin II/aldolase C and phospholipase Cβ4, to reveal the topography of the cerebellum in microchiropteran bats. Three species of bat were studied, Lasiurus cinereus, Lasionycteris noctivagans, and Eptesicus fuscus. A reproducible pattern of zones and stripes was revealed that is similar across the three species. The architecture of the bat cerebellum conforms to the ground plan of other mammals. However, two exceptions to the highly conserved mammalian architectural plan were revealed. First, many Purkinje cells in lobule I express zebrin II. A zebrin II‐immunopositive lobule I has not been seen previously in mammals but is characteristic of the avian cerebellum. Second, lobules VI–VII comprise the large central zone. Within the central zone two subdomains are evident, a small anterior subdomain (lobule VI) in which Purkinje cells are predominantly zebrin II‐immunopositive/PLCβ4‐immunonegative, as in other mammals, and a posterior subdomain (lobule VII), in which alternating zebrin II/phospholipase Cβ4 stripes are prominent. J. Comp. Neurol. 517:193–209, 2009. © 2009 Wiley‐Liss, Inc.
Distribution of high‐conductance calcium‐activated potassium channels in rat vestibular epithelia
Authors: Schweizer Felix E. , Savin David , Luu Cindy , Sultemeier David R. , Hoffman Larry F.
Published: July 2009

Voltage‐ and calcium‐activated potassium channels (BK) are important regulators of neuronal excitability. BK channels seem to be crucial for frequency tuning in nonmammalian vestibular and auditory hair cells. However, there are a paucity of data concerning BK expression in mammalian vestibular hair cells. We therefore investigated the localization of BK channels in mammalian vestibular hair cells, specifically in rat vestibular neuroepithelia. We find that only a subset of hair cells in the utricle and the crista ampullaris express BK channels. BK‐positive hair cells are located mainly in the medial striolar region of the utricle, where they constitute at most 12% of hair cells, and in the central zone of the horizontal crista. A majority of BK‐positive hair cells are encapsulated by a calretinin‐positive calyx defining them as type I cells. The remainder are either type I cells encapsulated by a calretinin‐negative calyx or type II hair cells. Surprisingly, the number of BK‐positive hair cells in the utricle peaks in juvenile rats and declines in early adulthood. BK channels were not found in vestibular afferent dendrites or somata. Our data indicate that BK channel expression in the mammalian vestibular system differs from the expression pattern in the mammalian auditory and the nonmammalian vestibular system. The molecular diversity of vestibular hair cells indicates a functional diversity that has not yet been fully characterized. The predominance of BK‐positive hair cells within the medial striola of juvenile animals suggests that they contribute to a scheme of highly lateralized coding of linear head movements during late development. J. Comp. Neurol. 517:134–145, 2009. © 2009 Wiley‐Liss, Inc.
Treadmill training enhances axon regeneration in injured mouse peripheral nerves without increased loss of topographic specificity
Authors: English Arthur W. , Cucoranu Delia , Mulligan Amanda , Sabatier Manning
Published: July 2009

We investigated the extent of misdirection of regenerating axons when that regeneration was enhanced by using treadmill training. Retrograde fluorescent tracers were applied to the cut proximal stumps of the tibial and common fibular nerves 2 or 4 weeks after transection and surgical repair of the mouse sciatic nerve. The spatial locations of retrogradely labeled motoneurons were studied in untreated control mice and in mice receiving 2 weeks of treadmill training, according to either a continuous protocol (10 m/minute, 1 hour/day, 5 days/week) or an interval protocol (20 m/minute for 2 minutes, followed by a 5‐minute rest, repeated four times, 5 days/week). More retrogradely labeled motoneurons were found in both treadmill‐trained groups. The magnitude of this increase was as great as or greater than that found after using other enhancement strategies. In both treadmill‐trained groups, the proportions of motoneurons labeled from tracer applied to the common fibular nerve that were found in spinal cord locations reserved for tibial motoneurons in intact mice were no greater than in untreated control mice and significantly less than those found after electrical stimulation or chondroitinase treatment. Treadmill training in the first 2 weeks following peripheral nerve injury produces a marked enhancement of motor axon regeneration without increasing the propensity of those axons to choose pathways leading to functionally inappropriate targets. J. Comp. Neurol. 517:245–255, 2009. © 2009 Wiley‐Liss, Inc.
Increased levels of NMDA receptor NR2A subunits at pre‐ and postsynaptic sites of the hippocampal CA1: An early response to conditional double knockout of presenilin 1 and 2
Authors: Aoki Chiye , Lee Joyce , Nedelescu Hermina , Ahmed Tunazzina , Ho Angela , Shen Jie
Published: July 2009

Greater than 90% of familial Alzheimer's disease (AD) is linked to mutations of presenilin (PS), and the loss of PS function altogether within mouse brains by conditional double knockout of the PS 1 and 2 genes (PS‐cDKO) leads to age‐dependent emergence of AD phenotypes, including neurodegeneration and reduced synaptic plasticity in the hippocampal CA1. The goal of our study was to identify the ultrastructural and molecular changes at synapses in the hippocampal CA1 of this PS‐cDKO mouse model of AD. We examined the asymmetric (excitatory) synapses formed on apical dendrites of CA1 pyramidal neurons at 2 months postnatal, an age when AD‐like symptoms emerge but brain morphology, as assessed by light microscopy, is still normal. Our quantitative electron microscopic analyses confirm that PS‐cDKO hippocampi at 2 months postnatal do not yet exhibit synapse losses or spine size alterations. However, immunocytochemistry reveals that the same region exhibits a 28% increase in the proportion of spines labeled for the NR2A subunits of NMDA receptors (NMDAR), with a 31% increase specifically at postsynaptic densities and a concomitant reduction of these subunits at nonsynaptic sites within spine heads. In contrast, no change in levels or the distribution pattern of NR2B subunit levels were detected within spine heads. Presynaptically, NR2A levels are elevated at axo‐spinous junctions and these may contribute to the timing‐dependent, long‐term depression. These observations point to an early‐onset trapping of NMDAR at synapses that are subtle but may underlie the reduced synaptic plasticity at 2 months of age and excitotoxicity at later stages. J. Comp. Neurol. 517:512–523, 2009. © 2009 Wiley‐Liss, Inc.
Inward rectifier channel, ROMK, is localized to the apical tips of glial‐like cells in mouse taste buds
Authors: Dvoryanchikov Gennady , Sinclair Michael S. , Perea‐Martinez Isabel , Wang Tong , Chaudhari Nirupa
Published: July 2009

Cells in taste buds are closely packed, with little extracellular space. Tight junctions and other barriers further limit permeability and may result in buildup of extracellular K+ following action potentials. In many tissues, inwardly rectifying K channels such as the renal outer medullary K (ROMK) channel (also called Kir1.1 and derived from the Kcnj1 gene) help to redistribute K+. Using reverse‐transcription polymerase chain reaction (RT‐PCR), we defined ROMK splice variants in mouse kidney and report here the expression of a single one of these, ROMK2, in a subset of mouse taste cells. With quantitative (q)RT‐PCR, we show the abundance of ROMK mRNA in taste buds is vallate > foliate > > palate > > fungiform. ROMK protein follows the same pattern of prevalence as mRNA, and is essentially undetectable by immunohistochemistry in fungiform taste buds. ROMK protein is localized to the apical tips of a subset of taste cells. Using tissues from PLCβ2‐GFP and GAD1‐GFP transgenic mice, we show that ROMK is not found in PLCβ2‐expressing type II/receptor cells or in GAD1‐expressing type III/presynaptic cells. Instead, ROMK is found, by single‐cell RT‐PCR and immunofluorescence, in most cells that are positive for the taste glial cell marker, Ectonucleotidase2. ROMK is precisely localized to the apical tips of these cells, at and above apical tight junctions. We propose that in taste buds, ROMK in type I/glial‐like cells may serve a homeostatic function, excreting excess K+ through the apical pore, and allowing excitable taste cells to maintain a hyperpolarized resting membrane potential. J. Comp. Neurol. 517:1–14, 2009. © 2009 Wiley‐Liss, Inc.
Effects of developmental age, brain region, and time in culture on long‐term proliferation and multipotency of neural stem cell populations
Authors: Gritti Angela , dal Molin Matteo , Foroni Chiara , Bonfanti Luca
Published: July 2009

Neural stem cells (NSCs) in the murine subventricular zone (SVZ) niche allow life‐long neurogenesis. During the first postnatal month and throughout aging, the decrease of neuroblasts and the rise of astrocytes results in diminished neurogenesis and increased astrocyte:neuron ratio. Also, a different neurogenic activity characterizes the SVZ periventricular region (LV, lateral ventricle) as compared to its rostral extension (RE). In order to investigate whether and to what extent these physiological modifications may be ascribed to intrinsic changes of the endogenous NSC/progenitor features, we performed a functional analysis on NSCs isolated and cultured from LV and RE tissues at distinct postnatal stages that are marked by striking modifications to the SVZ niche in vivo. We evaluated the effect of age and brain region on long‐term proliferation and multipotency, and characterized the cell type composition of NSC‐derived progeny, comparing this make‐up to that of region‐ and age‐matched primary neural cultures. Furthermore, we analyzed the effect of prolonged in vitro expansion on NSC functional properties. We documented age‐ and region‐dependent differences on the clonogenic efficiency and on the long‐term proliferative capacity of NSCs. Also, we found age‐ and region‐dependent quantitative changes in the cell composition of NSC progeny (decreased quantity of neurons and oligodendrocytes; increased amount of astroglial cells) and these differences were maintained in long‐term cultured NSC populations. Overall, these data strengthen the hypothesis that age‐ and region‐dependent differences in neurogenesis (observed in vivo) may be ascribed to the changes in the intrinsic developmental program of the NSC populations. J. Comp. Neurol. 517:333–349, 2009. © 2009 Wiley‐Liss, Inc.
PICK1 expression in the Drosophila central nervous system primarily occurs in the neuroendocrine system
Authors: Jansen Anna M. , Nässel Dick R. , Madsen Kenneth L. , Jung Anita G. , Gether Ulrik , Kjaerulff Ole
Published: July 2009

The protein interacting with C kinase 1 (PICK1) protein was first identified as a novel binding partner for protein kinase C. PICK1 contains a membrane‐binding BAR domain and a PDZ domain interacting with many synaptic proteins, including the α‐amino‐3‐hydroxy‐5‐methylisoxazole‐4‐propionic acid (AMPA) receptor subunit GluR2 and the dopamine transporter. PICK1 is strongly implicated in GluR2 trafficking and synaptic plasticity. In mammals, PICK1 has been characterized extensively in cell culture studies. To study PICK1 in an intact system, we characterized PICK1 expression immunohistochemically in the adult and larval Drosophila central nervous system. PICK1 was found in cell bodies in the subesophageal ganglion, the antennal lobe, the protocerebrum, and the neuroendocrine center pars intercerebralis. The cell types that express PICK1 were identified using GAL4 enhancer trap lines. The PICK1‐expressing cells form a subpopulation of neurons. PICK1 immunoreactivity was neither detected in glutamatergic nor in dopaminergic neurons. Also, we observed PICK1 expression in only a few GABAergic neurons, located in the antennal lobe. In contrast, we detected robust PICK1 immunolabeling of peptidergic neurons in the neuroendocrine system, which express the transcription factor DIMM and the amidating enzyme peptidylglycine‐α‐hydroxylating monooxygenase (PHM). The PICK1‐positive cells include neurosecretory cells that produce the insulin‐like peptide dILP2. PICK1 expression in insulin‐producing cells also occurs in mammals, as it was also observed in a rat insulinoma cell line derived from pancreatic β‐cells. At the subcellular level, PICK1 was found in the perinuclear zone but surprisingly not in synaptic domains. We conclude that PICK1 may serve an important role in the neuroendocrine system both in insects and vertebrates. J. Comp. Neurol. 517:313–332, 2009. © 2009 Wiley‐Liss, Inc.
Three‐dimensional properties of GnRH neuroterminals in the median eminence of young and old rats
Authors: Yin Weiling , Mendenhall John M. , Monita Monique , Gore Andrea C.
Published: July 2009

The decapeptide gonadotropin‐releasing hormone (GnRH), which regulates reproduction in all vertebrates, is stored in, and secreted from, large dense‐core secretory vesicles in nerve terminals in the median eminence. GnRH is released from these terminals with biological rhythms that are critical for the maintenance of normal reproduction. During reproductive aging in female rats, there is a loss of GnRH pulses and a diminution of the GnRH surge. However, information about the specific role of GnRH nerve terminals is lacking, particularly in the context of aging. We sought to gain novel ultrastructural information about GnRH neuroterminals by performing three‐dimensional (3D) reconstructions of GnRH neuroterminals and their surrounding microenvironment in the median eminence of young (4–5 months) and old (22–24 months) ovariectomized Sprague–Dawley female rats. Median eminence tissues were freeze‐plunge embedded and serial ultrathin sections were collected on slot grids for immunogold labeling of GnRH immunoreactivity. Sequential images were used to create 3D models of GnRH terminals. These reconstructions provided novel perspectives into the morphological properties of GnRH terminals and their neural and glial environment. We also noted that the cytoarchitectural features of the median eminence became disorganized with aging. Quantitative measures showed a significant decrease in the apposition between GnRH terminal membranes and glial cells. Our data suggest reproductive aging in rats is characterized by structural organizational changes to the GnRH terminal microenvironment in the median eminence. J. Comp. Neurol. 517:284–295, 2009. © 2009 Wiley‐Liss, Inc.
Developmental expression of prion protein and its ligands stress‐inducible protein 1 and vitronectin
Authors: Hajj Glaucia N.M. , Santos Tiago G. , Cook Zanith S.P. , Martins Vilma R.
Published: July 2009

Prion protein (PrPC) is the normal isoform of PrPSc, a protein involved in neurodegenerative disorders. PrPC participates in neuritogenesis, neuroprotection, and memory consolidation through its interaction with the secreted protein stress‐inducible protein 1 (STI1) and the extracellular matrix protein vitronectin (Vn). Although PrPC mRNA expression has been documented during embryogenesis, its protein expression patterns have not been evaluated. Furthermore, little is known about either Vn or STI protein expression. In this study, PrPC, STI1, and Vn protein expression was explored throughout mouse embryonic life. We found that the distributions of the three proteins were spatiotemporally related. STI1 and Vn expression became evident at E8, earlier than PrPC, in the nervous system and heart. At E10, we observed, in the spinal cord, a gradient of expression of the three proteins, more abundant in the notochord and floor plate, suggesting that they can have a role in axonal growth. As development proceeded, the three proteins were detected in other organs, suggesting that they may play a role in the development of nonneural tissues as well. Finally, although STI1 and Vn are PrPC ligands, their expression was not altered in PrPC‐null mice. J. Comp. Neurol. 517:371–384, 2009. © 2009 Wiley‐Liss, Inc.