bluuebunny/crossref_metadata_2025_split huggingface dataset:
Facile synthesis of unsaturated polyamines having hydroxyl groups by Pd(0)‐catalyzed polyaddition of bifunctional vinylepoxide and aliphatic amines
Authors: Koizumi Toshio , Shigematsu Akane , Maruyama Yukari , Nakui Tomoyuki 
Published: February 2008

AbstractUnsaturated polyamines having hydroxyl groups were synthesized by polymerization of a bifunctional vinylepoxide, 1,4‐bis(1‐methyl‐2‐vinylepoxyethyl)benzene (1), and aliphatic amines in the presence of a Pd(0) catalyst. The polyaddition was carried out for 24 h at 90°C in dioxane. Among the phosphine ligands employed, bis(2‐diphenylphosphinophenyl)ether (DPEphos) was most effective and gave polyamines with high molecular weight. Benzylamine and piperazine were appropriate nucleophiles and the corresponding polyamines were obtained in moderate to high yields, the number–average molecular weights (Mn) of which were high (Mn = 29,000–33,000). The polyaddition between 1 and anilines was not successful. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci 2008
New biodegradable blends prepared from polylactide, titanium tetraisopropylate, and starch
Authors: Liao Hsin‐Tzu , Wu Chin‐San 
Published: February 2008

AbstractIn this study, new biodegradable nanocomposites were prepared from poly(lactic acid) (PLA) or acrylic acid grafted poly(lactic acid) (PLA‐g‐AA), titanium tetraisopropylate, and starch by means of an in situ sol–gel process and the melt‐blending method. The samples were characterized with X‐ray diffractometry, Fourier transform infrared spectroscopy, differential scanning calorimetry, thermogravimetric analysis, scanning electron microscopy, and an Instron mechanical tester. According to the results, a PLA‐g‐AA/TiO2 hybrid could improve the properties of a PLA/TiO2 hybrid because the carboxylic acid groups of acrylic acid should act as coordination sites for the titania phase to form the TiOC chemical bond. It was also found that both the tensile strength and glass‐transition temperature increased to a maximum value and then decreased with increasing TiO2 because excess particles (e.g., greater than 10 wt % TiO2) could cause separation or segregation between the organic and inorganic phases. A PLA‐g‐AA/TiO2/starch hybrid could obviously enhance the mechanical properties of a PLA‐g‐AA/starch hybrid because the former could provide a smaller starch phase size and nanoscale dispersion of TiO2 in the polymer matrix. The biodegradable nanocomposites produced in our laboratory could provide a plateau tensile strength at break when the starch content was up to 50 wt %. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci 2008
Artificial structures as tools for fish habitat rehabilitation in a neotropical reservoir
Authors: Santos Luciano N. , Araújo Francisco G. , Brotto Daniel S. 
Published: February 2008

Abstract
Since most of the natural habitats critical for freshwater fish survival have been adversely affected by human disturbance, the effectiveness of artificial structures in providing new and suitable habitats for fish has been increasingly investigated.
This paper evaluates the role of artificial structures as fish habitat in a structureless 30 km2 Brazilian reservoir, through underwater surveys conducted monthly from April 1999 to March 2000.
In total, 5759 fish in nine species were recorded, but only three cichlid species—one native, Geophagus brasiliensis and two non‐native, Cichla kelberi and Tilapia rendalli—showed consistent association with the artificial habitats, suggesting that this family reacts to submerged structures.
The absence of fish at control sites compared with high occurrences in sites provided with a physically complex structure suggests that artificial structures can play an important ecological role for cichlids smaller than 150 mm TL, probably related to shelter and/or feeding benefits.
The level of structural complexity and position in the water column influenced fish use of artificial structures. C. kelberi was associated with highly complex structures, whereas moderately complex bottom structures were more effective in harbouring G. brasiliensis. Bottom structures are apparently more important than midwater structures in harbouring T. rendalli, but structural complexity seemed to play a secondary role.
This study is the first in demonstrating that adding complex artificial structures can expand habitats for small fish (<150 mm TL), especially cichlids, in a neotropical impoundment. It seems reasonable to expect that deploying physically complex structures in other oligotrophic, structureless and cichlid‐dominated impoundments in Brazil will lead to similar results to those found in this work.
Copyright © 2008 John Wiley & Sons, Ltd.
Muscarinic acetylcholine receptors in macaque V1 are most frequently expressed by parvalbumin‐immunoreactive neurons
Authors: Disney Anita A. , Aoki Chiye 
Published: February 2008

AbstractAcetylcholine (ACh) is believed to underlie mechanisms of arousal and attention in mammals. ACh also has a demonstrated functional effect in visual cortex that is both diverse and profound. We have reported previously that cholinergic modulation in V1 of the macaque monkey is strongly targeted toward GABAergic interneurons. Here we examine the localization of m1 and m2 muscarinic receptor subtypes across subpopulations of GABAergic interneurons—identified by their expression of the calcium‐binding proteins parvalbumin, calbindin, and calretinin—using dual‐immunofluorescence confocal microscopy in V1 of the macaque monkey. In doing so, we find that the vast majority (87%) of parvalbumin‐immunoreactive neurons express m1‐type muscarinic ACh receptors. m1 receptors are also expressed by 60% of calbindin‐immunoreactive neurons and 40% of calretinin‐immunoreactive neurons. m2 AChRs, on the other hand, are expressed by only 31% of parvalbumin neurons, 23% of calbindin neurons, and 25% of calretinin neurons. Parvalbumin‐immunoreactive cells comprise ≈75% of the inhibitory neuronal population in V1 and included in this large subpopulation are neurons known to veto and regulate the synchrony of principal cell spiking. Through the expression of m1 ACh receptors on nearly all of these PV cells, the cholinergic system avails itself of powerful control of information flow through and processing within the network of principal cells in the cortical circuit. J. Comp. Neurol. 507:1748–1762, 2008. © 2008 Wiley‐Liss, Inc.
Stress experienced in utero reduces sexual dichotomies in neurogenesis, microenvironment, and cell death in the adult rat hippocampus
Authors: Mandyam Chitra D. , Crawford Elena F. , Eisch Amelia J. , Rivier Catherine L. , Richardson Heather N. 
Published: February 2008

AbstractHippocampal function and plasticity differ with gender, but the regulatory mechanisms underlying sex differences remain elusive and may be established early in life. The present study sought to elucidate sex differences in hippocampal plasticity under normal developmental conditions and in response to repetitive, predictable versus varied, unpredictable prenatal stress (PS). Adult male and diestrous female offspring of pregnant rats exposed to no stress (control), repetitive stress (PS‐restraint), or a randomized sequence of varied stressors (PS‐random) during the last week of pregnancy were examined for hippocampal proliferation, neurogenesis, cell death, and local microenvironment using endogenous markers. Regional volume was also estimated by stereology. Control animals had comparable proliferation and regional volume regardless of sex, but females had lower neurogenesis compared to males. Increased cell death and differential hippocampal precursor kinetics both appear to contribute to reduced neurogenesis in females. Reduced local interleukin‐1beta (IL‐1β) immunoreactivity (IR) in females argues for a mechanistic role for the anti‐apoptotic cytokine in driving sex differences in cell death. Prenatal stress significantly impacted the hippocampus, with both stress paradigms causing robust decreases in actively proliferating cells in males and females. Several other hippocampal measures were feminized in males such as precursor kinetics, IL‐1β‐IR density, and cell death, reducing or abolishing some sex differences. The findings expand our understanding of the mechanisms underlying sex differences and highlight the critical role early stress can play on the balance between proliferation, neurogenesis, cell death, and hippocampal microenvironment in adulthood. © 2008 Wiley Periodicals, Inc. Develop Neurobiol, 2008.
Reelin is essential for neuronal migration but not for radial glial elongation in neonatal ferret cortex
Authors: Schaefer Alisa , Poluch Sylvie , Juliano Sharon 
Published: February 2008

AbstractNumerous functions related to neuronal migration are linked to the glycoprotein reelin. Reelin also elongates radial glia, which are disrupted in mutant reeler mice. Our lab developed a model of cortical dysplasia in ferrets that shares features with the reeler mouse, including impaired migration of neurons into the cerebral cortex and disrupted radial glia. Explants of normal ferret cortex in coculture with dysplastic ferret cortex restore the deficits in this model. To determine if reelin is integral to the repair, we used explants of P0 mouse cortex either of the wild type (WT) or heterozygous (het) for the reelin gene, as well as P0 reeler cortex (not containing reelin), in coculture with organotypic cultures of dysplastic ferret cortex. This arrangement revealed that all types of mouse cortical explants (WT, het, reeler) elongated radial glia in ferret cortical dysplasia, indicating that reelin is not required for proper radial glial morphology. Migration of cells into ferret neocortex, however, did not improve with explants of reeler cortex, but was almost normal after pairing with WT or het explants. We also placed an exogenous source of reelin in ferret cultures at the pial surface to reveal that migrating cells move toward the reelin source in dysplastic cortex; radial glia in these cultures were also improved toward normal. Our results demonstrate that the normotopic position of reelin is important for proper neuronal positioning, and that reelin is capable of elongating radial glial cells but is not the only radialization factor. © 2008 Wiley Periodicals, Inc. Develop Neurobiol, 2008.
Genetic dissection reveals two separate pathways for rod and cone regeneration in the teleost retina
Authors: Morris Ann C. , Scholz Tamera L. , Brockerhoff Susan E. , Fadool James M. 
Published: February 2008

AbstractDevelopment of therapies to treat visual system dystrophies resulting from the degeneration of rod and cone photoreceptors may directly benefit from studies of animal models, such as the zebrafish, that display continuous retinal neurogenesis and the capacity for injury‐induced regeneration. Previous studies of retinal regeneration in fish have been conducted on adult animals and have relied on methods that cause acute damage to both rods and cones, as well as other retinal cell types. We report here the use of a genetic approach to study progenitor cell responses to photoreceptor degeneration in the larval and adult zebrafish retina. We have compared the responses to selective rod or cone degeneration using, respectively, the XOPS‐mCFP transgenic line and zebrafish with a null mutation in the pde6c gene. Notably, rod degeneration induces increased proliferation of progenitors in the outer nuclear layer (ONL) and is not associated with proliferation or reactive gliosis in the inner nuclear layer (INL). Molecular characterization of the rod progenitor cells demonstrated that they are committed to the rod photoreceptor fate while they are still mitotic. In contrast, cone degeneration induces both Müller cell proliferation and reactive gliosis, with little change in proliferation in the ONL. We found that in both lines, proliferative responses to photoreceptor degeneration can be observed as 7 days post fertilization (dpf). These two genetic models therefore offer new opportunities for investigating the molecular mechanisms of selective degeneration and regeneration of rods and cones. © 2008 Wiley Periodicals, Inc. Develop Neurobiol, 2008.
Expression patterns and cell cycle profiles of PCNA, MCM6, cyclin D1, cyclin A2, cyclin B1, and phosphorylated histone H3 in the developing mouse retina
Authors: Barton Kirston M. , Levine Edward M. 
Published: February 2008

AbstractA challenge in studying organogenesis is the ability to identify progenitor cell populations. To address this problem, we characterized the expression patterns of cell cycle proteins during mouse retinal development and used flow cytometry to determine the expression profiles in the cell cycle. We found that MCM6 and PCNA are expressed in essentially all retinal progenitor cells throughout the proliferative period and these proteins are readily detectable in all cell cycle phases. Furthermore, their expression levels are downregulated as cells exit the cell cycle and differentiate. We also analyzed the expression of Cyclins D1, A2, and B1, and phosphorylated Histone H3 and found unexpected expression patterns and cell cycle profiles. The combined utilization of the markers tested and the use of flow cytometry should further facilitate the study of stem and progenitor cell behavior during development and in adult tissues. Developmental Dynamics 237:672–682, 2008. © 2008 Wiley‐Liss, Inc.
Trichostatin A (TSA) improves the development of rabbit‐rabbit intraspecies cloned embryos, but not rabbit‐human interspecies cloned embryos
Authors: Shi Li‐Hong , Miao Yi‐Liang , Ouyang Ying‐Chun , Huang Jun‐Cheng , Lei Zi‐Li , Yang Ji‐Wen , Han Zhi‐Ming , Song Xiang‐Fen , Sun Qing‐Yuan , Chen Da‐Yuan 
Published: February 2008

AbstractThe interspecies somatic cell nuclear transfer (iSCNT) technique for therapeutic cloning gives great promise for treatment of many human diseases. However, the incomplete nuclear reprogramming and the low blastocyst rate of iSCNT are still big problems. Herein, we observed the effect of TSA on the development of rabbit–rabbit intraspecies and rabbit–human interspecies cloned embryos. After treatment with TSA for 6 hr during activation, we found that the blastocyst rate of rabbit–rabbit cloned embryos was more than two times higher than that of untreated embryos; however, the blastocyst rate of TSA‐treated rabbit–human interspecies cloned embryos decreased. We also found evident time‐dependent histone deacetylation‐reacetylation changes in rabbit–rabbit cloned embryos, but not in rabbit–human cloned embryos from fusion to 6 hr after activation. Our results suggest that TSA‐treatment does not improve blastocyst development of rabbit–human iSCNT embryos and that abnormal histone deacetylation‐reacetylation changes in iSCNT embryos may account for their poor blastocyst development. Developmental Dynamics 237:640–648, 2008. © 2008 Wiley‐Liss, Inc.
The incomplete inactivation of Fgf8 in the limb ectoderm affects the morphogenesis of the anterior autopod through BMP‐mediated cell death
Authors: Delgado Irene , Domínguez‐Frutos Elena , Schimmang Thomas , Ros Maria A. 
Published: February 2008

AbstractHere we analyze limb development after the conditional inactivation of Fgf8 from the epiblast, using the previously described MORE (Mox2Cre) line. This line drives variable mosaic recombination of a floxed Fgf8 allele, resulting in a small proportion of AER cells that maintain Fgf8 expression. The phenotype of Mox2Cre;Fgf8 limbs is most similar to that of Msx2Cre;Fgf8 forelimbs, indicating that a small but durable expression of FGF8 is equivalent to an early normal, but transitory, expression. This functional equivalence likely relies on the subsequent Fgf4 upregulation that buffers the differences in the pattern of Fgf8 expression between the two conditional mutants. The molecular analysis of Mox2Cre;Fgf8 limbs shows that, despite Fgf4 upregulation, they develop under reduced FGF signaling. These limbs also exhibit an abnormal area of cell death at the anterior forelimb autopod, overlapping with an ectopic domain of Bmp7 expression, which can explain the abnormal morphogenesis of the anterior autopod. Developmental Dynamics 237:649–658, 2008. © 2008 Wiley‐Liss, Inc.
A hedgehog homolog is involved in muscle formation and organization of Sepia officinalis (mollusca) mantle
Authors: Grimaldi Annalisa , Tettamanti Gianluca , Acquati Francesco , Bossi Elena , Guidali Maria Luisa , Banfi Serena , Monti Laura , Valvassori Roberto , de Eguileor Magda 
Published: February 2008

AbstractOur study focuses on the possible involvement of the Hedgehog (Hh) pathway in the differentiation of striated muscle fibres in cuttlefish (Sepia officinalis) mantle. We show here that both an hh‐homolog signalling molecule and its receptor Patched (Ptc) are expressed in a specific population of myoblasts which differentiates into the radial fast fibres. To evaluate the functional significance of hh expression in developing cuttlefish, we inhibited the Hedgehog signalling pathway by means of cyclopamine treatment in cuttlefish embryos. In treated embryos, the gross anatomy was considerably compromised, displaying an extremely reduced mantle with a high degree of morphological abnormalities. TUNEL and BrdU assays showed that the absence of an hh signalling induces apoptosis and reduces the proliferation rate of muscle precursors. We therefore hypothesize a possible involvement of Hh and its receptor Ptc in the formation of striated muscle fibres in cuttlefish. Developmental Dynamics 237:659–671, 2008. © 2008 Wiley‐Liss, Inc.
Transitioning from egg to embryo: Triggers and mechanisms of egg activation
Authors: Horner Vanessa L. , Wolfner Mariana F. 
Published: February 2008

AbstractThe transition from mature oocyte to developing embryo requires a coordinated series of events, collectively known as egg activation. Egg activation includes changes to egg coverings to prevent polyspermy, release of oocyte meiotic arrest, generation of haploid female and male pronuclei, changes in maternal mRNAs and protein populations, and cytoskeletal rearrangements. In many animals, egg activation is triggered by fertilization, which increases intracellular calcium within the oocyte and thereby regulates molecular events of egg activation. In other animals, fertilization‐independent external signals, including mechanical stimulation of eggs and/or changes in ionic milieu, trigger activation. Recent studies have clarified the upstream portion of pathways leading to eggshell changes and cell cycle resumption and have identified activation‐induced changes in maternal mRNA and protein profiles that can identify molecular players in the downstream events of egg activation. We review signals that trigger activation and how they link to subsequent molecular events of egg activation. Developmental Dynamics 237:527–544, 2008. © 2008 Wiley‐Liss, Inc.
Zygotic loss of ZEN‐4/MKLP1 results in disruption of epidermal morphogenesis in the C. elegans embryo
Authors: Hardin Jeff , King Ryan , Thomas‐Virnig Christina , Raich William B. 
Published: February 2008

AbstractZEN‐4/MKLP1 is required maternally for cytokinesis in Caenorhabditis elegans, but was originally identified in a screen for zygotic lethal, enclosure abnormal (Zen) mutants. We report that zen‐4(w35) homozygotes exhibit stochastic failures in cytokinesis in multiple lineages. Remarkably, multinucleate epidermal cells show directional migration, even when there are as few as half the normal number of cells. Temperature shift experiments and analysis of zen‐4::gfp expression confirm that the epidermal requirement for zen‐4 function precedes morphogenesis. Driving expression of wild‐type zen‐4 by means of an epithelial‐specific transgene can rescue many epidermal morphogenetic defects in zen‐4 mutants. Early expression of unc‐119 in epidermal precursors made this promoter unsuitable as a neuronal‐specific driver in this context. Our results indicate that zygotic zen‐4 function is required for correct division of epidermal precursors and, hence, indirectly for normal morphogenesis and that the epidermal morphogenetic program is surprisingly robust even in the absence of zen‐4 function. Developmental Dynamics 237:830–836, 2008. © 2008 Wiley‐Liss, Inc.
Adaptive Nanowires for On‐Demand Control of Electrochemical Microsystems
Authors: Wang J. 
Published: February 2008

AbstractNanowires are critically important building blocks of nanotechnology. Much of the excitement on nanowires arisen from with the ability to introduce different chemical functions through the use of multiple segments along these nanoscale objects. The multifunctionality of such multisegment nanowires allows these nanostructures to perform several tasks simultaneously. This short review covers recently developed protocols based on adaptive multifunctional magnetic nanowires for controlling on‐demand the operation of electrochemical sensors and microchip devices and for triggering and modulating electrocatalytic and bioelectrocatalytic processes. Magnetic stimulus can be used for activating reversibly various bioelectrocatalytic and electrocatalytic processes through controlled surface orientation of multifunctional magnetic nanowires. The ability to use adaptive nanowires to switch electrochemical devices between active and passive states will be illustrated for protecting electrochemical sensors against surface fouling and for controlling amperometric detection for separation microchips. Such nanowire‐based adaptive operation should lead to the next‐generation of ‘smart’ self‐activated analytical and bioelectronic devices.
MEMS Device to Monitor Biological Oxygen Uptake at Arrays of Single Cells and Small Cell Clusters
Authors: Sheth Disha B. , Suresh Gayathri , Yang Jian , Ladas Thomas , Zorman Christian A. , Gratzl Miklós 
Published: February 2008

AbstractOxygen uptake by a cell is indicative of metabolic processes which are modulated by extracellular stimuli and is characteristic of a cell's physiological status. In this work, a MEMS platform with an array of microsensors to monitor these processes at cell constructs is being developed. An array of Pt microring electrodes has been fabricated to quantitatively assess oxygen uptake by normal and pharmacologically manipulated BAC1.2F5 macrophage cells positioned at cell attachment sites inside the microrings. An amperometric pulsing protocol was implemented to reduce interference with cellular metabolism caused by depletion of oxygen during the measurement. We were able to detect changes as small as 1% in oxygen concentration in the vicinity of single cells and small cell clusters. Thus, the approach can be used for sensitive indication of oxygen uptake by cell(s) and its modulation by environmental factors such as pharmacological agents, and interaction with adjacent cells. Moreover, parallel experiments at different cell attachment sites are made feasible by the sensor array. This can provide multiple data sets for biostatistics in the same amount of time that is required to get a single data set.