bluuebunny/crossref_metadata_2025 huggingface dataset:
Modeling Spontaneous Activity in the Developing Spinal Cord Using Activity-Dependent Variations of Intracellular Chloride
Authors: Marchetti Cristina , Tabak Joel , Chub Nikolai , O'Donovan Michael J. , Rinzel John
Published: April 2005

We investigated how spontaneous activity is generated in developing, hyperexcitable networks. We focused our study on the embryonic chick spinal cord, a preparation that exhibits rhythmic discharge on multiple timescales: slow episodes (lasting minutes) and faster intraepisode cycling (∼1 Hz frequency). For this purpose, we developed a mean field model of a recurrent network with slow chloride dynamics and a fast depression variable. We showed that the model, in addition to providing a biophysical mechanism for the slow dynamics, was able to account for the experimentally observed activity. The model made predictions on how interval and duration of episodes are affected when changing chloride-mediated synaptic transmission or chloride flux across cell membrane. These predictions guided experiments, and the model results were compared with experimental data obtained with electrophysiological recordings. We found agreement when transmission was affected through changes in synaptic conductance and good qualitative agreement when chloride flux was varied through changes in external chloride concentration or in the rate of the Na+-K+-2Cl-cotransporter. Furthermore, the model made predictions about the time course of intracellular chloride concentration and chloride reversal potential and how these are affected by changes in synaptic conductance. Based on the comparison between modeling and experimental results, we propose that chloride dynamics could be an important mechanism in rhythm generation in the developing chick spinal cord.
Matrix Metalloproteinase-3: A Novel Signaling Proteinase from Apoptotic Neuronal Cells That Activates Microglia
Authors: Kim Yoon Seong , Kim Sung Soo , Cho Jeong Je , Choi Dong Hee , Hwang Onyou , Shin Dong Hoon , Chun Hong Sung , Beal M. Flint , Joh Tong H.
Published: April 2005

Microglial activation and inflammation are associated with progressive neuronal apoptosis in neurodegenerative human brain disorders. We sought to investigate molecular signaling mechanisms that govern activation of microglia in apoptotic neuronal degeneration. We report here that the active form of matrix metalloproteinase-3 (MMP-3) was released into the serum-deprived media (SDM) of PC12 cells and other media of apoptotic neuronal cells within 2-6 h of treatment of the cells, and SDM and catalytic domain of recombinant MMP-3 (cMMP-3) activated microglia in primary microglia cultures as well as BV2 cells, a mouse microglia cell line. Both SDM and cMMP-3 induced generation of tumor necrosis factor α (TNF-α), interleukin-6 (IL-6), IL-1β, and interleukin-1 receptor antagonist but not IL-12 and inducible nitric oxide synthase, which are readily induced by lipopolysaccharide, in microglia, suggesting that there is a characteristic pattern of microglial cytokine induction by apoptotic neurons. Neither glial cell line-derived neurotrophic factor nor anti-inflammatory cytokines, such as IL-10 and transforming growth factor-β1, were induced. SDM and cMMP-3 extensively released TNF-α from microglia and activated the nuclear factor-κB pathway, and these microglial responses were totally abolished by preincubation with an MMP-3 inhibitor, NNGH [N-isobutyl-N-(4-methoxyphenylsulfonyl)-glycylhydroxamic acid]. MMP-3-mediated microglial activation mostly depended on ERK (extracellular signal-regulated kinase) phosphorylation but not much on either JNK (c-Jun N-terminal protein kinase) or p38 activation. Conditioned medium of SDM- or cMMP-3-activated BV2 cells caused apoptosis of PC12 cells. These results strongly suggest that the distinctive signal of neuronal apoptosis is the release of active form of MMP-3 that activates microglia and subsequently exacerbates neuronal degeneration. Therefore, the release of MMP-3 from apoptotic neurons may play a major role in degenerative human brain disorders, such as Parkinson's disease.
Shank Expression Is Sufficient to Induce Functional Dendritic Spine Synapses in Aspiny Neurons
Authors: Roussignol Gautier , Ango Fabrice , Romorini Stefano , Tu Jian Cheng , Sala Carlo , Worley Paul F. , Bockaert Joël , Fagni Laurent
Published: April 2005

Shank proteins assemble glutamate receptors with their intracellular signaling apparatus and cytoskeleton at the postsynaptic density. Whether Shank plays a role in spinogenesis and synaptogenesis remained unclear. Here, we report that knock-down of Shank3/prolinerich synapse-associated protein-2 by RNA interference reduces spine density in hippocampal neurons. Moreover, transgene expression of Shank 3 is sufficient to induce functional dendritic spines in aspiny cerebellar neurons. Transfected Shank protein recruits functional glutamate receptors, increases the number and size of synaptic contacts, and increases amplitude, frequency, and the AMPA component of miniature EPSCs, similar to what is observed during synapse developmental maturation. Mutation/deletion approaches indicate that these effects require interactions of Shank3 with the glutamate receptor complex. Consistent with this observation, chronic treatment with glutamate receptor antagonists alters maturation of the Shank3-induced spines. These results strongly suggest that Shank proteins and the associated glutamate receptors participate in a concerted manner to form spines and functional synapses.
Visual Control of Burst Priming in the Anesthetized Lateral Geniculate Nucleus
Authors: Denning Kate S. , Reinagel Pamela
Published: April 2005

Thalamic relay cells fire bursts of action potentials. Once a long hyperpolarization “primes” (deinactivates) the T-type calcium channel, a depolarizing input will “trigger” a calcium spike with a burst of action potentials. During sleep, bursts are frequent, rhythmic, and nonvisual. Bursts have been observed in alert animals, and burst timing is known to carry visual information under light anesthesia. We extend this finding by showing that bursts without visual triggers are rare. Nevertheless, if the channel were primed at random with respect to the stimulus, then bursts would have the same visual significance as single spikes. We find, however, that visual signals influence when the channel is primed. First, natural time-varying stimuli evoke more bursts than white noise. Second, specific visual stimuli reproducibly elicit bursts, whereas others reliably elicit single spikes. Therefore, visual information is encoded by the selective tagging of some responses as bursts. The visual information attributable to visual priming (as distinct from the information attributable to visual triggering of the bursts) was two bits per burst on average. Although bursts are reportedly rare in alert animals, this must be investigated as a function of visual stimulus. Moreover, we propose methods to measure the extent of both visual triggering and visual priming of bursts. Whether or not bursts are rare, our methods could help determine whether bursts in alert animals carry a distinct visual signal.
Attentional Modulation of Learning-Related Repetition Attenuation Effects in Human Parahippocampal Cortex
Authors: Yi Do-Joon , Chun Marvin M.
Published: April 2005

Two of the most fundamental processes in biological vision are attention and learning. Attention actively selects and enhances visual information that is most relevant to behavior. Learning enables the visual system to benefit from perceptual experience. The amount of visual information to learn is infinite; however, top-down control mechanisms must somehow regulate learning to achieve an adaptive balance between plasticity and stability in neural circuitry. Functional magnetic resonance imaging (fMRI) can measure learning-related changes in neural activity to previously viewed perceptual stimuli. Described variably as the repetition suppression or adaptation effect, the attenuation in neural activity to repeated stimuli versus novel stimuli provides a marker for stimuli-specific perceptual processing and memory. One important issue concerns whether repetition attenuation is automatic or not, and recent work has begun to show that it is sensitive to task demands. Accordingly, the present study further examined how attention controls the attenuated response to repeated stimuli, specifically testing whether attention is important for initial encoding, for the expression of memory traces, or for both encoding and expression. To manipulate attention, we used overlapping scene and face images and asked subjects to attend to either category. fMRI revealed significant attenuation in the parahippocampal place area for only the repeated scenes that were attended both during the initial presentation and during repetition. Thus, attention actively governs when neuronal activity is attenuated to repeated perceptual input, and such attention is important during both initial encoding and subsequent expression of the learned information.
Spinal G-Protein-Gated Potassium Channels Contribute in a Dose-Dependent Manner to the Analgesic Effect of μ- and δ- But Not κ-Opioids
Authors: Marker Cheryl L. , Luján Rafael , Loh Horace H. , Wickman Kevin
Published: April 2005

Opioids can evoke analgesia by inhibiting neuronal targets in either the brain or spinal cord, and multiple presynaptic and postsynaptic inhibitory mechanisms have been implicated. The relative significance of presynaptic and postsynaptic inhibition to opioid analgesia is essentially unknown, as are the identities and relevant locations of effectors mediating opioid actions. Here, we examined the distribution of G-protein-gated potassium (GIRK) channels in the mouse spinal cord and measured their contribution to the analgesia evoked by spinal administration of opioid receptor-selective agonists. We found that the GIRK channel subunits GIRK1 and GIRK2 were concentrated in the outer layer of the substantia gelatinosa of the dorsal horn. GIRK1 and GIRK2 were found almost exclusively in postsynaptic membranes of putative excitatory synapses, and a significant degree of overlap with the μ-opioid receptor was observed. Although most GIRK subunit labeling was perisynaptic or extrasynaptic, GIRK2 was found occasionally within the synaptic specialization. Genetic ablation or pharmacologic inhibition of spinal GIRK channels selectively blunted the analgesic effect of high but not lower doses of the μ-opioid receptor-selective agonist [d-Ala(2),N-Me-Phe(4),Gly(5)-ol]-enkephalin. Dose-dependent contributions of GIRK channels to the analgesic effects of the δ-opioid receptor-selective agonists Tyr-d-Ala-Phe-Glu-Val-Val-Gly amide and [d-Pen(2,5)]-enkephalin were also observed. In contrast, the analgesic effect of the κ agonist (trans)-3,4-dichloro-N-methyl-N-[2-(1-pyrrolidinyl)-cyclohexyl] benzeneacetamide methanesulfonate hydrate was preserved despite the absence of GIRK channels. We conclude that the activation of postsynaptic GIRK1 and/or GIRK2-containing channels in the spinal cord dorsal horn represents a powerful, albeit relatively insensitive, means by which intrathecal μ- and δ-selective opioid agonists evoke analgesia.
Spectral Edge Sensitivity in Neural Circuits of the Dorsal Cochlear Nucleus
Authors: Reiss Lina A. J. , Young Eric D.
Published: April 2005

One possible function of the dorsal cochlear nucleus (DCN) is discrimination of head-related transfer functions (HRTFs), spectral cues used for vertical sound localization. Recent psychophysical and physiological studies suggest that steep, rising spectral edges may be the features used to identify HRTFs. Here we showed, using notch noise and noise band stimuli presented over a range of frequencies, that a subclass of DCN type IV neurons responded with a response peak when the rising spectral edge of a notch or band was aligned near best frequency (BF). This edge sensitivity was correlated with weak or inhibited responses to broadband noise and inhibition in receptive fields at frequencies below BF. Some aspects of the inhibition shaping the response peak, namely inhibition to rising edges below BF and to falling edges at BF, could be explained by the properties of type II interneurons with BFs below those of the type IV neurons. However, many type IV neurons also showed inhibitory responses with the rising spectral edge just above BF, and these responses could not be reproduced by current models of DCN circuitry. Therefore, a new component of the DCN circuit is needed to fully explain the responses to rising spectral edges. This shaping of edge sensitivity by inhibition to rising spectral edges both below and above BF suggests the specialization of DCN for spectral edge coding along the tonotopic gradient.
Selective Modulation of Neuronal Nicotinic Acetylcholine Receptor Channel Subunits by Go-Protein Subunits
Authors: Fischer Harald , Liu Dong-Mei , Lee Aven , Harries Janet C. , Adams David J.
Published: April 2005

G-protein modulation of neuronal nicotinic acetylcholine receptor (nAChR) channels in rat intrinsic cardiac ganglia was examined using dialyzed whole-cell and excised membrane patch-recording configurations. Cell dialysis with GTPγS increased the agonist affinity of nAChRs, resulting in a potentiation of nicotine-evoked whole-cell currents at low concentrations. ACh- and nicotine-evoked current amplitudes were increased approximately twofold in the presence of GTPγS. In inside-out membrane patches, the open probability (NPo) of nAChR-mediated unitary currents was reversibly increased fourfold after bath application of 0.2 mmGTPγS relative to control but was unchanged in the presence of GDPβS. The modulation of nAChR-mediated whole-cell currents was agonist specific; currents evoked by the cholinergic agonists ACh, nicotine, and 1,1-dimethyl-4-phenylpiperazinium iodide, but not cytisine or choline, were potentiated in the presence of GTPγS. The direct interaction between G-protein subunits and nAChRs was examined by bath application of either Goα or Gβγ subunits to inside-out membrane patches and in glutathioneS-transferase pull-down and coimmunoprecipitation experiments. Bath application of 50 nmGβγ increased the open probability of ACh-activated single-channel currents fivefold, whereas Goα (50 nm) produced no significant increase in NPo. Neuronal nAChR subunits α3-α5 and β2 exhibited a positive interaction with Goα and Gβγ, whereas β4 and α7 failed to interact with either of the G-protein subunits. These results provide evidence for a direct interaction between nAChR and G-protein subunits, underlying the increased open probability of ACh-activated single-channel currents and potentiation of nAChR-mediated whole-cell currents in parasympathetic neurons of rat intrinsic cardiac ganglia.
Impeded Interaction between Schwann Cells and Axons in the Absence of Laminin α4
Authors: Wallquist Wilhelm , Plantman Stefan , Thams Sebastian , Thyboll Jill , Kortesmaa Jarkko , Lännergren Jan , Domogatskaya Anna , Ögren Sven Ove , Risling Mårten , Hammarberg Henrik , Tryggvason Karl , Cullheim Staffan
Published: April 2005

The Schwann cell basal lamina (BL) is required for normal myelination. Loss or mutations of BL constituents, such as laminin-2 (α2β1γ1), lead to severe neuropathic diseases affecting peripheral nerves. The function of the second known laminin present in Schwann cell BL, laminin-8 (α4β1γ1), is so far unknown. Here we show that absence of the laminin α4 chain, which distinguishes laminin-8 from laminin-2, leads to a disturbance in radial sorting, impaired myelination, and signs of ataxia and proprioceptive disturbances, whereas the axonal regenerative capacity is not influenced.In vitrostudies show poor axon growth of spinal motoneurons on laminin-8, whereas it is extensive on laminin-2. Schwann cells, however, extend longer processes on laminin-8 than on laminin-2, and, in contrast to the interaction with laminin-2, solely use the integrin receptor α6β1 in their interaction with laminin-8. Thus, laminin-2 and laminin-8 have different critical functions in peripheral nerves, mediated by different integrin receptors.
Consumer, retailer, and producer assessments of product differentiation according to regional origin and process quality
Authors: Wirthgen Antje
Published: April 2005

Regional marketing concepts can be a successful strategy for product differentiation. A research project in Northern Germany reveals the following results: consumers' stated preferences show clearly potential demand for regional food, in particular if environment‐friendly produced and controlled. The main influencing factors that could be identified by means of a rank‐ordered logit analysis are consumers' regional, nutrition, and environment consciousness as well as a low price sensitivity and mistrust in conventional food from somewhere else.

Also some retailers indicated interest in regional marketing concepts, but rarely in environment‐friendly produced food: listing of regional specialities and a seasonal offer as well as a farmer's market outlet in a shopping center. Further, farmers showed general interest in regional marketing, but not combined with environment‐friendly production. Overall, one can conclude of these results, that the limiting factor for regional marketing seems to be more the supply than the demand side. [EconLit citations: Q130, M310.] © 2005 Wiley Periodicals, Inc. Agribusiness 21: 191–211, 2005.
Marketing margins and price transmission on the Hungarian pork meat market
Authors: Bakucs Lajos Zoltán , Fertõ Imre
Published: April 2005

The analysis of vertical price relationship along the supply chain from producers to consumers has become a popular tool of evaluating the efficiency and degree of competition in agrifood systems over recent decades. There is a wealth of literature on the farm‐retail price spread for different commodities and countries. However, with one exception (Bojnec, 2002) none have studied price transmission and marketing margins in the transition economies. It is a common belief that because of the distorted markets inherited from the pre 1989 period, the deficiency of the price‐discovery mechanisms, and unpredictable policy interventions, marketing margins are generally larger in the transition economies than in competitive markets. Using cointegration analysis, we find that producer and retail pork meat prices are cointegrated, the retail prices entering the cointegration space as weakly exogenous variables. Structural tests imposing homogeneity conditions are carried out and show a competitive pricing strategy. Price transmission modeling suggests that, despite the common belief, price transmission on the Hungarian pork meat market is symmetric. [JEL classification: Q13, D12, D4.] © 2005 Wiley Periodicals, Inc. Agribusiness 21: 273–286, 2005.
Cover Picture: Topochemical Photodimerization in the Coordination Polymer [{(CF3CO2)(μ‐O2CCH3)Zn}2(μ‐bpe)2]n through Single‐Crystal to Single‐Crystal Transformation (Angew. Chem. Int. Ed. 15/2005)
Authors: Toh Ni Lian , Nagarathinam Mangayarkarasi , Vittal Jagadese J.
Published: April 2005

Railroad polymers are one‐dimensional metal coordination polymers that form a molecular ladder structure. The cover picture shows such a structure, comprised of Zn–(4,4′‐bipyridylethylene) units, which undergoes [2 + 2] photochemical cycloaddition across the rails to form another 1D coordination polymeric structure accompanied by quantitative single‐crystal to single‐crystal transformation. For more details see the Communication by J. J. Vittal and co‐workers on page 2237 ff. (The cover picture was designed by Bellam Sreenivasulu.)
Photoresponses and pH responses of hydrogels composed of acrylamido azobenzene and acrylic acid
Authors: Chen Li , Li Shi‐Geng , Zhao Yi‐Ping , Wang Yu‐Cui , Wang Qing‐Wen
Published: April 2005

A monomer with a side‐chain azobenzide, acrylamido azobenzene (AAAB), was synthesized, and a series of poly(acrylic acid‐co‐acrylamido azobenzene) polymers and gels were prepared through the copolymerization of this AAAB monomer with acrylic acid. Their responses to pH and ultraviolet light were studied. These copolymers and gels showed good pH responses and photoresponses; these responses were caused by the ionization of carboxyl and the cis–trans isomerism of azobenzide, respectively. The molecular structures of the copolymers and gels were also studied with X‐ray diffraction, and the results showed that the copolymers with a certain amount of AAAB could form crystalline structures. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 2163–2167, 2005
Synthesis of reactor blend of linear and branched polyethylene using metallocene/Ni‐diimine binary catalyst system in a single reactor
Authors: AlObaidi Fahad , Zhu Shiping
Published: April 2005

This work reports the synthesis of a series of reactor blends of linear and branched polyethylene materials using a combination of [1,4‐bis(2,6‐diisopropylphenyl) acenaphthene diimine nickel(II) dibromide] (1)/MMAO, known as an active catalyst for the production of branched polyethylene, and [rac‐ethylenebis(indenyl) zirconium dichloride] (2)/MMAO, which is active for the production of linear polyethylene. The polymerization runs were performed at various levels of temperature, pressure, and catalyst 2 molar fractions. At 5°C, there was very low influence of catalyst 2 molar fraction on the overall catalyst activity. However, at 30°C and 50°C, the overall catalyst activity increased linearly with catalyst 2 molar fraction. The same linear dependency was also found for the polymerization reactions carried out at 60°C and 100°C. At various levels of temperature and ethylene pressure, higher melting temperature and crystallinity were observed with an increase in catalyst 2 molar fraction. At 60°C and 100 psig, the DSC thermograms of the polymers produced with 1/2/MMAO exhibited two distinct peaks with melting temperatures closely corresponding to the melting temperatures of the polymers produced with the individual catalysts, 1/MMAO and 2/MMAO. The GPCV analysis of all polyethylene samples showed monomodal molecular weight distributions with low polydispersities. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 2212–2217, 2005
Influence of precipitated silica on dynamic mechanical properties and resistance to oil and thermal aging in CPE/NR blends
Authors: Pattanawanidchai Sirichai , Saeoui Pongdhorn , Sirisinha Chakrit
Published: April 2005

Blends of 80/20 CPE/NR filled with various silica loadings were prepared, and their properties were determined. It was found that cure properties are influenced significantly by the addition of precipitated silica. Scorch time and cure time decrease with increasing silica loading, which could be explained by the thermal history attributed to the shear heating in the blending stage. An increase in crosslink density as a function of silica loading is believed to be caused by a migration of curatives to the NR phase. In terms of phase morphology, with increasing silica loading, the NR dispersed phase size decreases due to the increase in compound viscosity and, thus, the shear stress available for efficient blending. An increase in silica loading also enhances resistance to oil due to the decrease in the NR dispersed phase size associated with the dilution effect, but gives no significant impact on thermal aging resistance. According to the change in damping peak height associated with the shift in Tg of the CPE phase, silica appears to preferentially migrate to the CPE phase due to the strong interaction between CPE and silanol groups of the silica surfaces. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 2218–2224, 2005
Modeling parison formation in extrusion blow molding by neural networks
Authors: Huang Han‐Xiong , Lu Song
Published: April 2005

A series of experiments were carried out on the parison formation stage in extrusion blow molding of high‐density polyethylene (HDPE) under different die temperature, extrusion flow rate, and parison length. The drop time of parison when it reached a given length and its swells, including the diameter, thickness, and area swells, were determined by analyzing its video images. Two back‐propagation (BP) artificial neural network models, one for predicting the length evolution of parison with its drop time, the other predicting the swells along the parison, were constructed based on the experimental data. Some modifications to the original BP algorithm were carried out to speed it up. The comparison of the predicted parison swells using the trained BP network models with the experimentally determined ones showed quite a good agreement between the two. The sum of squared error for the predictions is within 0.001. The prediction of the parison diameter and thickness distributions can be made online at any parison length or any parison drop time within a given range using the trained models. The predicted parison swells were analyzed. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 2230–2239, 2005
Gelation of soybean oil with polybutadiene
Authors: Yilmaz Mustafa , Kusefoğlu Seli̇m H.
Published: April 2005

In this study self‐supporting, resilient, load bearing polybutadiene ‐ soybean oil gels were obtained. The gels were made by dissolving polybutadiene (PBD) in soybean oil (SO) and selectively crosslinking PBD with a free radical source. PBD concentration, free radical source concentration, and the temperature and time of the crosslinking reaction were varied, and the effects of these changes on the mechanical properties of the gels were examined. Our experiments show that successful gelation is possible within PBD concentration limits of 7.5 to 12%, peroxide concentration between 25 to 100% (based on PBD), temperature between 110°C and 130°C and reaction times of 3 hours with tert.butyl‐peroxybenzoate as the free radical source. The crosslinking reaction was followed by IR and H‐NMR spectra, and the crosslinking density was followed by compression testing and swelling behavior. Higher radical source concentration and higher PBD concentration gave gels with better mechanical properties. The spectra and the viscosity increase of SO extracted from the gels indicate that there is dimer and trimer formation of SO during the reaction. The spectra of the PBD extracted from gels indicate that SO was added to PBD in a small but measurable amount. Integration of peak intensities in the NMR spectrum of methylene groups of PBD and methylene groups of triglyceride indicated one triglyceride molecule for approximately 45 repeating units in PBD. The modulus of the best gel sample (PBD 10%. peroxide 50%) was 1.96 × 10−2 MPa. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 2240–2246, 2005
Structural chemoproteomics and drug discovery
Authors: Shin Dongkyu , Heo Yong‐Seok , Joo Lee Kyung , Min Kim Cheol , Min Yoon Jung , Il Lee Jae , Hyun Young‐Lan , Ho Jeon Young , Gyu Lee Tae , Myung Cho Joong , Ro Seonggu
Published: April 2005

Our laboratories have developed several technologies to accelerate drug discovery process on the basis of structural chemoproteomics. They include SPS™ technology for the efficient determination of protein structures, SCP™ technology for the rapid lead generation and SDF™ technology for the productive lead optimization. Using these technologies, we could determine many 3D structures of target proteins bound with biologically active chemicals including the structure of phosphodiesterase 5/Viagra complex and obtain highly potent compounds in animal models of obesity, diabetes, cancer and inflammation. In this paper, we will discuss concepts and applications of structural chemoproteomics for drug discovery. © 2005 Wiley Periodicals, Inc. Biopolymers (Pept Sci), 2005
Interaction and structural study of kinin peptide bradykinin and ganglioside monosialylated 1 micelle
Authors: Chatterjee Chiradip , Mukhopadhyay Chaitali
Published: April 2005

Partitioning of small proteins and peptides from the aqueous to membrane phase is often coupled with folding. In this work we examine the binding and folding of the kinin peptide, bradykinin (BK), in the presence of the ganglioside monosialylated 1 (GM1) micelle. Using two‐dimensional NMR techniques, we have shown that at low concentration, GM1 micelle is able to induce a turn conformation to BK. A pulsed‐field gradient diffusion NMR study indicated that the peptide partitions into the GM1 micelle with a ΔGpart of −3.14 ± 0.03 kcal/mol. A saturation transfer difference (STD) NMR study indicated that the binding is mostly through hydrophobic residues. © 2005 Wiley Periodicals, Inc. Biopolymers 78: 197–205, 2005
Stoichiometric limitations in assembly of active recombinant retrovirus
Authors: Lei Pedro , Andreadis Stelios T.
Published: April 2005

Although recombinant retroviruses are widely used in gene therapy and as gene transfer vehicles for basic biological studies, their titers are very low as compared to other recombinant viral systems, e.g., adenovirus. We investigated the rate‐limiting steps in production of LacZ‐encoding ecotropic (CRE BAG 2) and amphotropic (Ψ‐CRIP) retrovirus. We found that ecotropic retrovirus producer cells produced a large number of inactive viral particles because they were severely limited by the amount of mRNA that was packaged into viral capsids. Introduction of the gene for green fluorescence protein (GFP) increased retroviral titers 40‐fold, without affecting the viral matrix protein, p30, or the activity of reverse transcriptase. Surprisingly, while transfer of GFP gene increased retrovirus production, β‐gal activity and X‐gal titer decreased significantly. Quantitative real‐time polymerase chain reaction (PCR) showed that although producer cells synthesized similar amounts of both mRNAs, retroviral supernatants contained significantly lower amount of LacZ mRNA, possibly due to competition between LacZ and GFP mRNAs for encapsidation into virions. In contrast to ecotropic producers, introduction of GFP gene copies into amphotropic producers resulted in a moderate twofold increase in retrovirus production. However, delivery of genes encoding for the viral proteins gp70 and p30 increased virus production by fivefold, suggesting that amphotropic producers may also be limited by synthesis of structural viral proteins. Our data show that in addition to the amount of viral genome or proteins, assembly of viral components into active viral particles may limit production of high titer retroviral preparations. © 2005 Wiley Periodicals, Inc.
Searching Sequence Space: Two Different Approaches to Dihydrofolate Reductase Catalysis
Authors: Howell Elizabeth E.
Published: April 2005

There are numerous examples of proteins that catalyze the same reaction while possessing different structures. This review focuses on two dihydrofolate reductases (DHFRs) that have disparate structures and discusses how the catalytic strategies of these two DHFRs are driven by their respective scaffolds. The two proteins are E. coli chromosomal DHFR (Ec DHFR) and a type II R‐plasmid‐encoded DHFR, typified by R67 DHFR. The former has been described as a very well evolved enzyme with an efficiency of 0.15, while the latter has been suggested to be a model for a “primitive” enzyme that has not yet been optimized by evolution. This comparison underlines what is important to catalysis in these two enzymes and concurrently highlights fundamental issues in enzyme catalysis.
Generation of Novel Landomycins M and O through Targeted Gene Disruption
Authors: Luzhetskyy Andriy , Zhu Lili , Gibson Miranda , Fedoryshyn Marta , Dürr Clemens , Hofmann Carsten , Hoffmeister Dirk , Ostash Bohdan , Mattingly Cynthia , Adams Val , Fedorenko Victor , Rohr Jürgen , Bechthold Andreas
Published: April 2005

Two genes from Streptomyces cyanogenous S136 that encode the reductase LanZ4 and the hydroxylase LanZ5, which are involved in landomycin A biosynthesis, were characterized by targeted gene inactivation. Analyses of the corresponding mutants as well as complementation experiments have allowed us to show that LanZ4 and LanZ5 are responsible for the unique C‐11‐hydroxylation that occurs during landomycin biosynthesis. Compounds accumulated by the lanZ4/Z5 mutants are the previously described landomycin F and the new landomycins M and O.
Convenient Access Both to Highly Antimalaria‐Active 10‐Arylaminoartemisinins, and to 10‐Alkyl Ethers Including Artemether, Arteether, and Artelinate
Authors: Haynes Richard K. , Chan Ho‐Wai , Ho Wing‐Yan , Ko Cliff Ki‐Fung , Gerena Lucia , Kyle Dennis E. , Peters Wallace , Robinson Brian L.
Published: April 2005

An economical phase‐transfer method is used to prepare 10‐arylaminoartemisinins from DHA and arylamines, and artemether, arteether, and artelinate from the corresponding alcohols. In vivo sc screens against Plasmodium berghei and P. yoelii in mice reveal that the p‐fluorophenylamino derivative 5 g is some 13 and 70 times, respectively, more active than artesunate; this reflects the very high sc activity of 10‐alkylaminoartemisinins. However, through the po route, the compounds are less active than the alkylaminoartemisinins, but still approximately equipotent with artesunate.
Cover Picture: A Novel Mycolactone from a Clinical Isolate of Mycobacterium ulcerans Provides Evidence for Additional Toxin Heterogeneity as a Result of Specific Changes in the Modular Polyketide Synthase (ChemBioChem 4/2005)
Authors: Hong Hui , Spencer Jonathan B. , Porter Jessica L. , Leadlay Peter F. , Stinear Tim
Published: April 2005

The cover picture shows the structure (in red, right) of the lipophilic polyketide toxin mycolactone obtained from the reference Ghana strain of Mycobacterium ulcerans, the causative agent of the emerging disease Buruli ulcer, and that (in red, left) of a molecular variant of mycolactone newly identified from a clinical isolate of M. ulcerans from China. The new variant bears a single additional methyl group in the sidechain, as shown by mass spectrometry. Also shown at the top is the difference detected between the structural genes; this difference is dictated by a precise acyltransferase (AT) domain swap in the chain‐building polyketide synthase, so that a propionate (Pr) unit is recruited rather than an acetate (Ac) unit. Detailed information about this apparent natural example of polyketide biosynthetic engineering is reported by P. Leadley et al. on p. 643 ff.
Overestimation of aortic valve gradient measured by Doppler echocardiography in patients with aortic stenosis
Authors: Sakthi Chellammal , Yee Henry , Kotlewski Adam
Published: April 2005

We describe a series of patients with suspected aortic stenosis who were noted to have a significant aortic valve gradient by Doppler echocardiography but only a minimal gradient during cardiac catheterization. Although the pressure recovery phenomenon partially explained this discrepancy, a difference still persisted, particularly in peak gradients. The overestimation occurred at much lower cardiac catheterization gradients than previously reported. Since many of our patients were noted to be hypertensive, this discrepancy might be more apparent in this patient population. © 2005 Wiley‐Liss, Inc.
Congenital superior vena cava obstruction causing anasarca and respiratory failure in a newborn: Successful transcatheter therapy
Authors: Ro Pamela S. , Hill Sharon L. , Cheatham John P.
Published: April 2005

Superior vena cava (SVC) obstruction is a rare entity in the pediatric population. It usually presents in association with either previous cardiac surgery or external compression from a neoplasm. We present the case of an infant born with congenital SVC obstruction and significant bilateral chylothorax and anasarca necessitating mechanical ventilation. Successful placement of an intravascular stent led to resolution of the chylothoraces with rapid clinical improvement. © 2005 Wiley‐Liss, Inc.
Differential release of cardiac enzymes after percutaneous coronary intervention
Authors: Matthews Mark A. , Kunselman Susan J. , Gascho Joseph A. , Gilchrist Ian C.
Published: April 2005

We hypothesized that using calcium channel blockers (CCBs) that dilate microvasculature during percutaneous coronary intervention (PCI) would result in lower postprocedural creatine phosphokinase (CPK). PCI can be complicated by elevated CPK that has been associated with impaired microvascular perfusion. Nitroglycerin (NTG), the conventional PCI vasodilator, dilates epicardial arteries but does not affect the microvasculature. We hypothesized that using CCBs that dilate the microvasculature would result in lower postprocedural CPK values. Patients (n = 816) without evidence of acute myonecrosis undergoing PCI were divided into two groups based on whether they received intracoronary NTG or CCB during PCI. Postprocedural CPK values were compared using a repeated‐measures ANOVA and a random coefficient model. By repeated‐measures analysis, the NTG group had CPK values of 88%, 83%, and 89% of the CCB group's CPK values at < 8, 8–14, and > 14 hr after PCI (P = 0.0080, 0.0002, and 0.0244), respectively. In a random coefficient model, the NTG group had CPK values 84%, 84%, and 89% of the CCB group's mean CPK values at 6, 12, and 18 hr after PCI (P = 0.0003, 0.0006, and 0.0403), respectively. Peak CPK values occurred earlier with CCB, although the maximal CPK was similar in both groups. Intracoronary CCB use is associated with an accelerated release of CPK after PCI compared with NTG. This is consistent with more efficient relief of microvascular obstruction with CCB. It suggests that myonecrosis may originate with vascular trauma at the time of PCI and its enzymatic expression is modifiable with different vasodilators. © 2005 Wiley‐Liss, Inc.
Renal frame count: A quantitative angiographic assessment of renal perfusion
Authors: Mulumudi Mahesh S. , White Christopher J.
Published: April 2005

Renal perfusion may be measured by a variety of noninvasive methods; however, there is no objective angiographic method to assess renal perfusion. We measured the renal frame count (RFC) in 26 patients (50 kidneys) with normal renal function and normal renal angiograms and 9 patients (15 kidneys) with renal artery fibromuscular dysplasia (FMD) and normal renal function. The mean age of the patients with normal renal arteries was 61.5 ± 9.5 (range, 47–82 years) and the mean age of patients with FMD was 72.5 ± 9.2 (range, 54–86 years; P = 0.005). There was no correlation between the age and RFC in both the normal renal artery group and the FMD group. The mean RFC for the normal renal arteries was 20.4 ± 3 (95% CI = 19.5–21.2), which was significantly lower than the FMD group's mean RFC of 26.9 ± 9.9 (95% CI = 21.4–32.4; P = 0.0001). RFC is an objective angiographic measure to quantify renal perfusion. Compared to normal renal arteries, those with FMD had significantly increased RFC consistent with decreased perfusion. © 2005 Wiley‐Liss, Inc.
Transition Metal Complexes of Cyclic and Open Ozone and Thiozone.
Authors: Flemming Beate , Wolczanski Peter T. , Hoffmann Roald
Published: April 2005

For Abstract see ChemInform Abstract in Full Text.
The Chemical Bonding in LaPdIn2, LaNiMg2, and LaNiCd2 — Intermetallic Compounds with a Filled Distorted Variant of the CaIn2 Type.
Authors: Dogan Ahmet , Johrendt Dirk , Poettgen Rainer
Published: April 2005

For Abstract see ChemInform Abstract in Full Text.
Preparation of Superconducting Nax(H2O)yCoO2 Using NaMnO4 as the Deintercalation and Oxidation Agent.
Authors: Liu Chia‐Jyi , Hung Wen‐Chin , Wang Jung‐Sheng , Liu Chia‐Jung Charlie
Published: April 2005

For Abstract see ChemInform Abstract in Full Text.
Assembly of Six‐Membered Vanadium Borophosphate Cluster Anions: Synthesis and Structures of (NH4)2 (C2H10N2)6 [Ba(H2O)5]2 [V2P2BO12] 6×8H2O and (NH4)8 (C3H12N2)4 [Ba(H2O)7] [V2P2BO12] 6×17H2O.
Authors: Yun Hoseop , Do Junghwan
Published: April 2005

For Abstract see ChemInform Abstract in Full Text.
Synthesis and Characterization of Cs2Mo6X14 (X: Br or I) Hexamolybdenum Cluster Halides: Efficient Mo6 Cluster Precursors for Solution Chemistry Syntheses.
Authors: Kirakci Kaplan , Cordier Stephane , Perrin Christiane
Published: April 2005

For Abstract see ChemInform Abstract in Full Text.
Highly Porous Uranyl Selenate Nanotubules.
Authors: Krivovichev Sergey V. , Kahlenberg Volker , Tananaev Ivan G. , Kaindl Reinhard , Mersdorf Edgar , Myasoedov Boris F.
Published: April 2005

For Abstract see ChemInform Abstract in Full Text.
Reactivity of N1‐Tosylamidrazones with Thiophosphorus Trichloride and Carbon Disulfide. Access to New Triazaphospholines and Triazolethiones.
Authors: Mosbah Mongi Ben , Chouaib Hanen , Kossentini Mohamed , Salem Mansour
Published: April 2005

For Abstract see ChemInform Abstract in Full Text.
One‐Pot Dehydrogenation of Carboxylic Acid Derivatives to α,β‐Unsaturated Carbonyl Compounds under Mild Conditions.
Authors: Matsuo Jun‐ichi , Aizawa Yayoi
Published: April 2005

For Abstract see ChemInform Abstract in Full Text.
Microwave Thermolysis. Part 9. A Rapid Reduction of Sulfoxides with NaH2PO2 in Dry Media.
Authors: Meshram H. M. , Ganesh Y. S. S. , Babu K. Ramesh , Eeshwaraiah B. , Yadav J. S.
Published: April 2005

For Abstract see ChemInform Abstract in Full Text.
A Practical Synthetic Method for Vinyl Chlorides and Vinyl Bromides from Ketones via the Corresponding Vinyl Phosphate Intermediates.
Authors: Kamei Katsuhide , Maeda Noriko , Tatsuoka Toshio
Published: April 2005

For Abstract see ChemInform Abstract in Full Text.
Microwave‐Assisted, Regioselective, Petasis Olefination of Unsymmetrical Oxalates. Formation of Pyruvate‐Based Enol Ethers and Enamines.
Authors: Cook Matthew J. , Fleming Declan W. , Gallagher Timothy
Published: April 2005

For Abstract see ChemInform Abstract in Full Text.
Caro′s Acid Supported on Silica Gel. Part 6. A Mild Reagent for Regeneration of Carbonyl Compounds from Acetals, Ketals, and 1,1‐Diacetates.
Authors: Lakouraj M. M. , Tajbakhsh M. , Khojasteh V. , Gholami M. H.
Published: April 2005

For Abstract see ChemInform Abstract in Full Text.
Photochemical and Radical Initiator‐Induced Reaction of Allylic Indium Compounds.
Authors: Hirashita Tsunehisa , Tanaka Jiro , Hayashi Ayumi , Araki Shuki
Published: April 2005

For Abstract see ChemInform Abstract in Full Text.
Synthesis of 1,4‐Diethynyl‐ and 1,1,4,4‐Tetraethynylbutatrienes.
Authors: Auffrant Audrey , Diederich Francois , Boudon Corinne , Gisselbrecht Jean‐Paul , Gross Maurice
Published: April 2005

For Abstract see ChemInform Abstract in Full Text.
Preparation of Fluoroalkyl Imines, Amines, Enamines, Ketones, α‐Amino Carbonyls, and α‐Amino Acids from Primary Enamine Phosphonates.
Authors: Palacios Francisco , Ochoa de Retana Ana Maria , Pascual Sergio , Oyarzabal Julen
Published: April 2005

For Abstract see ChemInform Abstract in Full Text.
Solvent‐Free Stereoselective Synthesis of cis‐1‐Carbomethoxy‐2‐aryl‐3,3‐dicyanocyclopropanes by Grinding.
Authors: Ren Zhongjiao , Cao Weiguo , Ding Weiyu , Shi Wen
Published: April 2005

For Abstract see ChemInform Abstract in Full Text.
The Multicomponent Reaction of Dimethoxycarbene, Dimethyl Butynedioate and Electrophilic Styrenes: An Unprecedented Synthesis of Highly Substituted Cyclopentenone Acetals.
Authors: Nair Vijay , Beneesh P. B. , Sreekumar V. , Bindu S. , Menon Rajeev S. , Deepthi Ani
Published: April 2005

For Abstract see ChemInform Abstract in Full Text.
[bmim]Br3 as a New Reagent for Regioselective Monobromination of Arylamines under Solvent‐Free Conditions.
Authors: Le Zhang‐Gao , Chen Zhen‐Chu , Hu Yi , Zheng Qin‐Guo
Published: April 2005

For Abstract see ChemInform Abstract in Full Text.
Rhodium‐Catalyzed Alkylation of Aromatic Azines with Alkenes via C—H Bond Activation.
Authors: Lim Yeong‐Gweon , Koo Bon Tak
Published: April 2005

For Abstract see ChemInform Abstract in Full Text.
Synthesis of [3H] Dapsone.
Authors: Egan Judith A. , Pounds Scot , Filer Christ N.
Published: April 2005

For Abstract see ChemInform Abstract in Full Text.
Vinyldimethylphenylsilanes as Safety Catch Silanols in Fluoride‐Free Palladium‐Catalyzed Cross‐Coupling Reactions.
Authors: Anderson James C. , Munday Rachel H.
Published: April 2005

For Abstract see ChemInform Abstract in Full Text.
LAH Aryl Alkyl Ether Cleavage of BINOL Derivatives.
Authors: Kowtoniuk Walter E. , MacFarland Darren K.
Published: April 2005

For Abstract see ChemInform Abstract in Full Text.
A New Route to Fullerene Substituted Phenylalanine Derivatives.
Authors: Yang Jianzhong , Barron Andrew R.
Published: April 2005

For Abstract see ChemInform Abstract in Full Text.
Ring‐Opening Reactions of Methylenecyclopropanes with Diphenyl Diselenide upon Heating; Formation of 3‐Phenylselenyl‐2,5‐dihydrofuran Derivatives.
Authors: Liu Le‐Ping , Shi Min
Published: April 2005

For Abstract see ChemInform Abstract in Full Text.
Convenient and Versatile Synthesis of Spiro(furan‐2,3‐indol[2]ones) and Spiro(pyran‐2,3‐indol[2]ones).
Authors: Smet Mario , Van Oosterwijck Chantal , Van Hecke Kristof , Van Meervelt Luc , Vandendriessche Annelies , Dehaen Wim
Published: April 2005

For Abstract see ChemInform Abstract in Full Text.
Transformation of Hydroxyiminoacetoacetanilides in Sulfuric Acid.
Authors: Ilyushkin D. I. , Semichenko E. S. , Suboch G. A.
Published: April 2005

For Abstract see ChemInform Abstract in Full Text.
Asymmetric Synthesis of 3‐Substituted Isoindolinones: Application to the Total Synthesis of (+)‐Lennoxamine.
Authors: Comins Daniel L. , Schilling Stefan , Zhang Yanchen
Published: April 2005

For Abstract see ChemInform Abstract in Full Text.
Synthesis of 1,3‐Diaryl‐4‐cyanopyrazoles from the Corresponding Aldoximes Using Dimethylformamide‐thionylchloride Complex.
Authors: Reddy G. Jagath , Sailaja S. , Pallavi K. , Rao K. Srinivasa
Published: April 2005

For Abstract see ChemInform Abstract in Full Text.
An Efficient Procedure for the Synthesis of Benzimidazole Derivatives Using Yb(OTf)3 as Catalyst under Solvent‐Free Conditions.
Authors: Wang Limin , Sheng Jia , Tian He , Qian Changtao
Published: April 2005

For Abstract see ChemInform Abstract in Full Text.
Studies on Cycloaddition Reactions of Vinylphosphonates with Nitrones.
Authors: Ye Yong , Li Ling‐Yun , Tian Li , Liu Lun‐Zu
Published: April 2005

For Abstract see ChemInform Abstract in Full Text.
2‐Acylimino‐3‐alkyl‐3H‐thiazoline Derivatives: One‐Pot, Three‐Component Condensation Synthesis of Novel β‐Turn Mimics.
Authors: Manaka Akira , Ishii Takaaki , Takahashi Keiko , Sato Masakazu
Published: April 2005

For Abstract see ChemInform Abstract in Full Text.
Polynuclear Tetrazole‐Containing Amino Acid Analogues
Authors: Morozova S. E. , Esikov K. A. , Zubarev V. Yu. , Malin A. A. , Ostrovskii V. A.
Published: April 2005

For Abstract see ChemInform Abstract in Full Text.
Efficient and Convenient Method for the Synthesis of Poly Functionalized 4H‐Pyrans.
Authors: Lingaiah B. P. V. , Reddy G. Venkat , Yakaiah T. , Narsaiah B. , Reddy S. N. , Yadla R. , Rao P. Shanthan
Published: April 2005

For Abstract see ChemInform Abstract in Full Text.
New 2‐Bromomethyl‐8‐substituted‐benzo[c]chromen‐6‐ones. Synthesis and Biological Properties.
Authors: Garino Cedrik , Bihel Frederic , Pietrancosta Nicolas , Laras Younes , Quelever Gilles , Woo Irene , Klein Peter , Bain Jenny , Boucher Jean‐Luc , Kraus Jean‐Louis
Published: April 2005

For Abstract see ChemInform Abstract in Full Text.
Synthesis of Substituted 1,4‐Dihydropyridines in Water Using Phase‐Transfer Catalyst under Microwave Irradiation.
Authors: Salehi Hojatollah , Guo Qing‐Xiang
Published: April 2005

For Abstract see ChemInform Abstract in Full Text.
Synthesis, Cardiovascular Activity, and Electrochemical Oxidation of Nitriles of 5‐Ethoxycarbonyl‐2‐methyl‐thio‐1,4‐dihydropyridine‐3‐carboxylic Acid.
Authors: Krauze A. , Baumane L. , Sile L. , Chernova L. , Vilums M. , Vitolina R. , Duburs G. , Stradins J.
Published: April 2005

For Abstract see ChemInform Abstract in Full Text.
Synthesis of 3,3‐Dialkyl‐1‐(3‐coumarinyl)‐3,4‐dihydroisoquinolines
Authors: Mikhailovskii A. G. , Vahrin M. I.
Published: April 2005

For Abstract see ChemInform Abstract in Full Text.
Amino‐Substituted Heterocycles as Isosteres of trans‐Cinnamides: Design and Synthesis of Heterocyclic Biaryl Sulfides as Potent Antagonists of LFA‐1/ICAM‐1 Binding.
Authors: Wang Gary T. , Wang Sheldon , Gentles Robert , Sowin Thomas , Leitza Sandra , Reilly Edward B. , von Geldern Thomas W.
Published: April 2005

For Abstract see ChemInform Abstract in Full Text.