bluuebunny/crossref_metadata_2025 huggingface dataset:
Mechanisms Underlying Directional Selectivity for Frequency-Modulated Sweeps in the Inferior Colliculus Revealed byIn VivoWhole-Cell Recordings
Authors: Gittelman Joshua X. , Li Na , Pollak George D.
Published: October 2009

Auditory neurons in the inferior colliculus (IC) show remarkable selectively in that they can distinguish between complex sounds that have identical spectral energy but different temporal structure, such as frequency modulations (FMs) that sweep either upward or downward. Extracellular recordings show that blocking inhibition locally reduces or eliminates response selectivity, suggesting that selectivity is createdde novoin the IC, with inhibition playing a prominent role. However, these studies can only infer underlying mechanisms based on spike counts. Usingin vivowhole-cell recordings, we examine the mechanisms underlying FM directional selectivity in the IC. We first report that spike threshold can strongly amplify directional selectivity in that the spike directionality was on average more than twice as large as the directionality of the postsynaptic potentials (PSPs). We then show that, in our sample of IC cells, PSP directional selectivity is not createdde novo. Rather, we found that the preferred and null FMs evoked synaptic conductances of different magnitudes, indicating that the presynaptic neurons were directionally selective. Combining conductance data with modeling, we show that directionally dependent magnitude differences, not temporal differences, underlie PSP directionality. Modeling also shows that our results are consistent with extracellular studies in which blocking inhibition reduces or eliminates directionality. Our findings suggest that some IC cells use a rate code in their inputs rather than a time code and that highly selective discharge properties can be created by only minor adjustments in the synaptic strengths evoked by different signals.
KIF5B Motor Adaptor Syntabulin Maintains Synaptic Transmission in Sympathetic Neurons
Authors: Ma Huan , Cai Qian , Lu Wenbo , Sheng Zu-Hang , Mochida Sumiko
Published: October 2009

Newly synthesized synaptic proteins and mitochondria are transported along lengthy neuronal processes to assist in the proper assembly of developing synapses and activity-dependent remodeling of mature synapses. Neuronal transport is mediated by motor proteins that associate with their cargoes via adaptors and travel along the cytoskeleton within neuronal processes. Our previous studies in developing hippocampal neurons revealed that syntabulin acts as a KIF5B motor adaptor and mediates anterograde transport of presynaptic cargoes and mitochondria, presynaptic assembly, and activity-induced plasticity. Here, using cultured superior cervical ganglion neurons combined with manipulation of syntabulin expression or interference with its interaction with KIF5B, we uncover a crucial role for syntabulin in the maintenance of presynaptic function. Syntabulin loss-of-function delayed the appearance of synaptic activity in developing neurons and impaired synaptic transmission in mature neurons, including reduced basal activity, accelerated synaptic depression under high-frequency firing, slowed recovery rates after synaptic vesicle depletion, and impaired presynaptic short-term plasticity. These defects correlated with reduced mitochondrial distribution along neuronal processes and were rescued by the application of ATP within presynaptic neurons. These results suggest that syntabulin supports the axonal transport of mitochondria and concomitant ATP production at presynaptic terminals. ATP supply from locally stationed mitochondria is in turn necessary for the efficient mobilization of synaptic vesicles into the readily releasable pool. These findings emphasize the critical role of KIF5B-syntabulin-mediated axonal transport in the maintenance of presynaptic function and regulation of synaptic plasticity.
Cytoskeletal Changes Underlie Estrogen's Acute Effects on Synaptic Transmission and Plasticity
Authors: Kramár Enikö A. , Chen Lulu Y. , Brandon Nicholas J. , Rex Christopher S. , Liu Feng , Gall Christine M. , Lynch Gary
Published: October 2009

Estrogen, in addition to its genomic effects in brain, causes rapid and reversible changes to synaptic operations. We report here that these acute actions are due to selective activation of an actin-signaling cascade normally used in the production of long-term potentiation (LTP). Estrogen, or a selective agonist of the steroid's β-receptor, caused a modest increase in fast glutamatergic transmission and a pronounced facilitation of LTP in adult hippocampal slices; both effects were completely eliminated by latrunculin, a toxin that prevents actin filament assembly. Estrogen also increased spine concentrations of filamentous actin and strongly enhanced its polymerization in association with LTP. A search for the origins of these effects showed that estrogen activates the small GTPase RhoA and phosphorylates (inactivates) the actin severing protein cofilin, a downstream target of RhoA. Moreover, an antagonist of RhoA kinase (ROCK) blocked estrogen's synaptic effects. Estrogen thus emerges as a positive modulator of a RhoA>ROCK>LIM kinase>cofilin pathway that regulates the subsynaptic cytoskeleton. It does not, however, strongly affect a second LTP-related pathway, involving the GTPases Rac and Cdc42 and their effector p21-activated kinase, which may explain why its acute effects are reversible. Finally, ovariectomy depressed RhoA activity, spine cytoskeletal plasticity, and LTP, whereas brief infusions of estrogen rescued plasticity, suggesting that the deficits in plasticity arise from acute, as well as genomic, consequences of hormone loss.
Corticostriatal Interactions during Learning, Memory Processing, and Decision Making
Authors: Pennartz Cyriel M. A. , Berke Joshua D. , Graybiel Ann M. , Ito Rutsuko , Lansink Carien S. , van der Meer Matthijs , Redish A. David , Smith Kyle S. , Voorn Pieter
Published: October 2009

This mini-symposium aims to integrate recent insights from anatomy, behavior, and neurophysiology, highlighting the anatomical organization, behavioral significance, and information-processing mechanisms of corticostriatal interactions. In this summary of topics, which is not meant to provide a comprehensive survey, we will first review the anatomy of corticostriatal circuits, comparing different ways by which “loops” of cortical–basal ganglia circuits communicate. Next, we will address the causal importance and systems-neurophysiological mechanisms of corticostriatal interactions for memory, emphasizing the communication between hippocampus and ventral striatum during contextual conditioning. Furthermore, ensemble recording techniques have been applied to compare information processing in the dorsal and ventral striatum to predictions from reinforcement learning theory. We will next discuss how neural activity develops in corticostriatal areas when habits are learned. Finally, we will evaluate the role of GABAergic interneurons in dynamically transforming cortical inputs into striatal output during learning and decision making.
The Epigenetics of Sex Differences in the Brain: Figure 1.
Authors: McCarthy Margaret M. , Auger Anthony P. , Bale Tracy L. , De Vries Geert J. , Dunn Gregory A. , Forger Nancy G. , Murray Elaine K. , Nugent Bridget M. , Schwarz Jaclyn M. , Wilson Melinda E.
Published: October 2009

Epigenetic changes in the nervous system are emerging as a critical component of enduring effects induced by early life experience, hormonal exposure, trauma and injury, or learning and memory. Sex differences in the brain are largely determined by steroid hormone exposure during a perinatal sensitive period that alters subsequent hormonal and nonhormonal responses throughout the lifespan. Steroid receptors are members of a nuclear receptor transcription factor superfamily and recruit multiple proteins that possess enzymatic activity relevant to epigenetic changes such as acetylation and methylation. Thus steroid hormones are uniquely poised to exert epigenetic effects on the developing nervous system to dictate adult sex differences in brain and behavior. Sex differences in the methylation pattern in the promoter of estrogen and progesterone receptor genes are evident in newborns and persist in adults but with a different pattern. Changes in response to injury and in methyl-binding proteins and steroid receptor coregulatory proteins are also reported. Many steroid-induced epigenetic changes are opportunistic and restricted to a single lifespan, but new evidence suggests endocrine-disrupting compounds can exert multigenerational effects. Similarly, maternal diet also induces transgenerational effects, but the impact is sex specific. The study of epigenetics of sex differences is in its earliest stages, with needed advances in understanding of the hormonal regulation of enzymes controlling acetylation and methylation, coregulatory proteins, transient versus stable DNA methylation patterns, and sex differences across the epigenome to fully understand sex differences in brain and behavior.
The Brain in Its Body: Motor Control and Sensing in a Biomechanical Context
Authors: Chiel Hillel J. , Ting Lena H. , Ekeberg Örjan , Hartmann Mitra J. Z.
Published: October 2009

Although it is widely recognized that adaptive behavior emerges from the ongoing interactions among the nervous system, the body, and the environment, it has only become possible in recent years to experimentally study and to simulate these interacting systems. We briefly review work on molluscan feeding, maintenance of postural control in cats and humans, simulations of locomotion in lamprey, insect, cat and salamander, and active vibrissal sensing in rats to illustrate the insights that can be derived from studies of neural control and sensing within a biomechanical context. These studies illustrate that control may be shared between the nervous system and the periphery, that neural activity organizes degrees of freedom into biomechanically meaningful subsets, that mechanics alone may play crucial roles in enforcing gait patterns, and that mechanics of sensors is crucial for their function.
Extrasynaptic GABAAReceptors: Form, Pharmacology, and Function
Authors: Belelli Delia , Harrison Neil L. , Maguire Jamie , Macdonald Robert L. , Walker Matthew C. , Cope David W.
Published: October 2009

GABA is the principal inhibitory neurotransmitter in the CNS and acts via GABAAand GABABreceptors. Recently, a novel form of GABAAreceptor-mediated inhibition, termed “tonic” inhibition, has been described. Whereas synaptic GABAAreceptors underlie classical “phasic” GABAAreceptor-mediated inhibition (inhibitory postsynaptic currents), tonic GABAAreceptor-mediated inhibition results from the activation of extrasynaptic receptors by low concentrations of ambient GABA. Extrasynaptic GABAAreceptors are composed of receptor subunits that convey biophysical properties ideally suited to the generation of persistent inhibition and are pharmacologically and functionally distinct from their synaptic counterparts. This mini-symposium review highlights ongoing work examining the properties of recombinant and native extrasynaptic GABAAreceptors and their preferential targeting by endogenous and clinically relevant agents. In addition, it emphasizes the important role of extrasynaptic GABAAreceptors in GABAergic inhibition throughout the CNS and identifies them as a major player in both physiological and pathophysiological processes.
Understanding the Role of DISC1 in Psychiatric Disease and during Normal Development
Authors: Brandon Nicholas J. , Millar J. Kirsty , Korth Carsten , Sive Hazel , Singh Karun K. , Sawa Akira
Published: October 2009

The biology of schizophrenia is complex with multiple hypotheses (dopamine, glutamate, neurodevelopmental) well supported to underlie the disease. Pathways centered on the risk factor “disrupted in schizophrenia 1” (DISC1) may be able to explain and unite these disparate hypotheses and will be the topic of this mini-symposium preview. Nearly a decade after its original identification at the center of a translocation breakpoint in a large Scottish family that was associated with major psychiatric disease, we are starting to obtain credible insights into its function and role in disease etiology. This preview will highlight a number of exciting areas of current DISC1 research that are revealing roles for DISC1 during normal brain development and also in the disease state. Together these different threads will provide a timely and exciting overview of the DISC1 field and its potential in furthering our understanding of psychiatric diseases and in developing new therapies.
Axonal Transport Defects in Neurodegenerative Diseases
Authors: Morfini Gerardo A. , Burns Matthew , Binder Lester I. , Kanaan Nicholas M. , LaPointe Nichole , Bosco Daryl A. , Brown Robert H. , Brown Hannah , Tiwari Ashutosh , Hayward Lawrence , Edgar Julia , Nave Klaus-Armin , Garberrn James , Atagi Yuka , Song Yuyu , Pigino Gustavo , Brady Scott T.
Published: October 2009

Adult-onset neurodegenerative diseases (AONDs) comprise a heterogeneous group of neurological disorders characterized by a progressive, age-dependent decline in neuronal function and loss of selected neuronal populations. Alterations in synaptic function and axonal connectivity represent early and critical pathogenic events in AONDs, but molecular mechanisms underlying these defects remain elusive. The large size and complex subcellular architecture of neurons render them uniquely vulnerable to alterations in axonal transport (AT). Accordingly, deficits in AT have been documented in most AONDs, suggesting a common defect acquired through different pathogenic pathways. These observations suggest that many AONDs can be categorized as dysferopathies, diseases in which alterations in AT represent a critical component in pathogenesis. Topics here address various molecular mechanisms underlying alterations in AT in several AONDs. Illumination of such mechanisms provides a framework for the development of novel therapeutic strategies aimed to prevent axonal and synaptic dysfunction in several major AONDs.
Analgesia Accompanying Food Consumption Requires Ingestion of Hedonic Foods
Authors: Foo H. , Mason Peggy
Published: October 2009

Animals eat rather than react to moderate pain. Here, we examined the behavioral, hedonic, and neural requirements for ingestion analgesia inad libitumfed rats. Noxious heat-evoked withdrawals were similarly suppressed during self-initiated chocolate eating and ingestion of intraorally infused water, sucrose, or saccharin, demonstrating that ingestion analgesia does not require feeding motivation, self-initiated food procurement, sucrose, or calories. Rather, food hedonics is important because neither salt ingestion nor quinine rejection elicited analgesia. During quinine-induced nausea and lipopolysaccharide (LPS)-induced illness, conditions when chocolate eating was presumably less pleasurable, analgesia accompanying chocolate consumption was attenuated, yet analgesia during water ingestion was preserved in LPS-injected rats who showed enhanced palatability for water within this context. The dependence of ingestion analgesia on the positive hedonics of an ingestate was confirmed in rats with a conditioned taste aversion to sucrose: after paired exposure to sucrose and LPS, rats no longer showed analgesia during sucrose ingestion but continued to show analgesia during chocolate consumption. Eating pauses tended to occur less often and for shorter durations in the presence of ingestion analgesia than in its absence. Therefore, we propose that ingestion analgesia functions to defend eating from ending. Muscimol inactivation of the medullary raphe magnus blocked the analgesia normally observed during water ingestion, showing the involvement of brainstem endogenous pain inhibitory mechanisms in ingestion analgesia. Brainstem-mediated defense of the consumption of palatable foods may explain, at least in part, why overeating tasty foods is so irresistible even in the face of opposing cognitive and motivational forces.
Nutrition, Brain Aging, and Neurodegeneration: Table 1.
Authors: Joseph James , Cole Greg , Head Elizabeth , Ingram Donald
Published: October 2009

The onset of age-related neurodegenerative diseases superimposed on a declining nervous system could enhance the motor and cognitive behavioral deficits that normally occur in senescence. It is likely that, in cases of severe deficits in memory or motor function, hospitalization and/or custodial care would be a likely outcome. This means that unless some way is found to reduce these age-related decrements in neuronal function, health care costs will continue to rise exponentially. Applying molecular biological approaches to slow aging in the human condition may be years away. So, it is important to determine what methods can be used today to increase healthy aging, forestall the onset of these diseases, and create conditions favorable to obtaining a “longevity dividend” in both financial and human terms. Recent studies suggest that consumption of diets rich in antioxidants and anti-inflammatory components such as those found in fruits, nuts, vegetables, and spices, or even reduced caloric intake, may lower age-related cognitive declines and the risk of developing neurodegenerative disease.
Protein Phosphatase 1 Regulates the Histone Code for Long-Term Memory
Authors: Koshibu Kyoko , Gräff Johannes , Beullens Monique , Heitz Fabrice D. , Berchtold Dominik , Russig Holger , Farinelli Mélissa , Bollen Mathieu , Mansuy Isabelle M.
Published: October 2009

Chromatin remodeling through histone posttranslational modifications (PTMs) and DNA methylation has recently been implicated in cognitive functions, but the mechanisms involved in such epigenetic regulation remain poorly understood. Here, we show that protein phosphatase 1 (PP1) is a critical regulator of chromatin remodeling in the mammalian brain that controls histone PTMs and gene transcription associated with long-term memory. Our data show that PP1 is present at the chromatin in brain cells and interacts with enzymes of the epigenetic machinery including HDAC1 (histone deacetylase 1) and histone demethylase JMJD2A (jumonji domain-containing protein 2A). The selective inhibition of the nuclear pool of PP1 in forebrain neurons in transgenic mice is shown to induce several histone PTMs that include not only phosphorylation but also acetylation and methylation. These PTMs are residue-specific and occur at the promoter of genes important for memory formation like CREB (cAMP response element-binding protein) and NF-κB (nuclear factor-κB). These histone PTMs further co-occur with selective binding of RNA polymerase II and altered gene transcription, and are associated with improved long-term memory for objects and space. Together, these findings reveal a novel mechanism for the epigenetic control of gene transcription and long-term memory in the adult brain that depends on PP1.
Cortical Deactivation Induced by Subcortical Network Dysfunction in Limbic Seizures
Authors: Englot Dario J. , Modi Badri , Mishra Asht M. , DeSalvo Matthew , Hyder Fahmeed , Blumenfeld Hal
Published: October 2009

Normal human consciousness may be impaired by two possible routes: direct reduced function in widespread cortical regions or indirect disruption of subcortical activating systems. The route through which temporal lobe limbic seizures impair consciousness is not known. We recently developed an animal model that, like human limbic seizures, exhibits neocortical deactivation including cortical slow waves and reduced cortical cerebral blood flow (CBF). We now find through functional magnetic resonance imaging (fMRI) that electrically stimulated hippocampal seizures in rats cause increased activity in subcortical structures including the septal area and mediodorsal thalamus, along with reduced activity in frontal, cingulate, and retrosplenial cortex. Direct recordings from the hippocampus, septum, and medial thalamus demonstrated fast poly-spike activity associated with increased neuronal firing and CBF, whereas frontal cortex showed slow oscillations with decreased neuronal firing and CBF. Stimulation of septal area, but not hippocampus or medial thalamus, in the absence of a seizure resulted in cortical deactivation with slow oscillations and behavioral arrest, resembling changes seen during limbic seizures. Transecting the fornix, the major route from hippocampus to subcortical structures, abolished the negative cortical and behavioral effects of seizures. Cortical slow oscillations and behavioral arrest could be reconstituted in fornix-lesioned animals by inducing synchronous activity in the hippocampus and septal area, implying involvement of a downstream region converged on by both structures. These findings suggest that limbic seizures may cause neocortical deactivation indirectly, through impaired subcortical function. If confirmed, subcortical networks may represent a target for therapies aimed at preserving consciousness in human temporal lobe seizures.
Input-Specific Intrasynaptic Arrangements of Ionotropic Glutamate Receptors and Their Impact on Postsynaptic Responses
Authors: Tarusawa Etsuko , Matsui Ko , Budisantoso Timotheus , Molnár Elek , Watanabe Masahiko , Matsui Minoru , Fukazawa Yugo , Shigemoto Ryuichi
Published: October 2009

To examine the intrasynaptic arrangement of postsynaptic receptors in relation to the functional role of the synapse, we quantitatively analyzed the two-dimensional distribution of AMPA and NMDA receptors (AMPARs and NMDARs, respectively) using SDS-digested freeze-fracture replica labeling (SDS-FRL) and assessed the implication of distribution differences on the postsynaptic responses by simulation. In the dorsal lateral geniculate nucleus, corticogeniculate (CG) synapses were twice as large as retinogeniculate (RG) synapses but expressed similar numbers of AMPARs. Two-dimensional views of replicas revealed that AMPARs form microclusters in both synapses to a similar extent, resulting in larger AMPAR-lacking areas in the CG synapses. Despite the broad difference in the AMPAR distribution within a synapse, our simulations based on the actual receptor distributions suggested that the AMPAR quantal response at individual RG synapses is only slightly larger in amplitude, less variable, and faster in kinetics than that at CG synapses having a similar number of the receptors. NMDARs at the CG synapses were expressed twice as many as those in the RG synapses. Electrophysiological recordings confirmed a larger contribution of NMDAR relative to AMPAR-mediated responses in CG synapses. We conclude that synapse size and the density and distribution of receptors have minor influences on quantal responses and that the number of receptors acts as a predominant postsynaptic determinant of the synaptic strength mediated by both the AMPARs and NMDARs.
Electron Scattering in Buried InGaAs MOSFET Channel with HfO2Gate Oxide
Authors: Oktyabrsky Serge , Nagaiah Padmaja , Tokranov Vadim , Koveshnikov Sergei , Yakimov Michael , Kambhampati Rama , Moore Richard , Tsai Wilman
Published: October 2009

Group III-V semiconductor materials are being studied as potential replacements for conventional CMOS technology due to their better electron transport properties. However, the excess scattering of carriers in MOSFET channel due to high-k gate oxide interface significantly depreciates the benefits of III-V high-mobility channel materials. We present results on Hall electron mobility of buried QW structures influenced by remote scattering due to InGaAs/HfO2interface. Mobility in In0.77Ga0.23As QWs degraded from 12000 to 1200 cm2/V-s and the mobility vs. temperature slope changed from T-1.2to almost T+1.0in 77-300 K range when the barrier thickness is reduced from 50 to 0 nm. This mobility change is attributed to remote Coulomb scattering due to charges and dipoles at semiconductor/oxide interface. Elimination of the InGaAs/HfO2interface via introduction of SiOxinterface layer formed by oxidation of thin a-Si passivation layer was found to improve the channel mobility. The mobility vs. sheet carrier density shows the maximum close to 2×1012cm-2.
First Principles Study of Metal/Bi2Te3Interfaces: Implications to Improve Contact Resistance
Authors: Xiong Ka , Wang Weichao , Alshareef Husam N , Gupta Rahul P , White John B , Gnade Bruce E , Cho Kyeongjae
Published: October 2009

We investigate the band offsets and stability for Ni/Bi2Te3and Co/Bi2Te3interfaces by first principles calculations. It is found that the surface termination strongly affects the band offsets. Ni and Co are found to form Ohmic contacts to Bi2Te3. The interface formation energies for Co/Bi2Te3interfaces are much lower than those of Ni/Bi2Te3interfaces. Our calculations are consistent with the experimental data.
Physics based models for metal hydride particle morphology, distribution, and effective thermal conductivity
Authors: Smith Kyle Christopher , Fisher Timothy
Published: October 2009

This paper describes a modeling approach to target aspects of heat conduction in metal hydride powders that are essential to metal hydrides as viable H2storage media, including particle morphology distribution, size distribution, particle packing properties at specified solid fraction, and effective thermal conductivity. An isotropic fracture model is presented that replicates features of particle size and shape distributions observed experimentally. The discrete element method is used to simulate evolution of metal hydride particle contact networks during quasi-static consolidation of decrepitated metal hydride powders. Finally, the effective thermal conductivity of such a powder is modeled assuming that contact conductance is the same for each interparticle contact.
Low dose genotoxicity of 4-bromo-n,n-diethyl-5,5- dimethyl-2,5-dihydro-1,2-oxaphosphol-2-amine 2-oxide in mice bone marrow cells and Allium cepa L. root tip cells
Authors: Kalcheva Vanya , Dragoeva Asya , Kalchev Karamfil , Enchev Dobromir
Published: October 2009

The chemistry of organophosphorus compounds is a subject of increasing interest and different new compounds have been synthesized. There are data that some known organophosphates are mutagens. Oxaphosphole derivatives possess biological activity and might influence proliferating cells. Bioassays are currently used in ecotoxicology to investigate the effects and mechanisms of action of new chemicals. To provide a broad coverage of the mutagenic potential of a chemical, information on different experimental test-systems is required. Genotoxicity assays are usually performed at high doses, but humans are exposed to most environmental chemicals at low doses. The objective of this study was to determine the genotoxicity of low doses (2.82x10-6 ?g/kg and 2.82x10-9 ?g/kg, corresponding to concentrations 10-12M and 10-15M) of 4-bromo-N,N-diethyl- 5,5-dimethyl-2,5-dihydro-1,2-oxaphosphol-2-amine 2-oxide (Br-oxph) in ICR mice bone marrow cells and Allium cepa L. root tip cells. Treatment with Br-oxph for 3 h produced alterations in the mitotic index in Allium cepa cells and induced chromosome aberrations in both test systems. These effects remained 48 h after the treatment. The data from the study showed the existence of cytotoxic and genotoxic effects of Br-oxph at tested doses.
Spike stability parameters in wheat grown on solonetz soil
Authors: Petrovic Sofija , Dimitrijevic Miodrag , Belic Milivoj , Banjac Borislav , Vukosavljev Mirjana
Published: October 2009

Phenotypic variability of the number and grain weight per spike, as well as the spike length of wheat varieties NSR-5, Evropa 90 and Pobeda creation of the Institute of Field and Vegetable Crops in Novi Sad was studied. The trial was conducted at the village Kumane locality in Banat on solonetz soil. Control and two levels of amelioration (25t/ha and 50t/ha of phosphor gypsum) in three vegetation periods were followed. The variety Evropa 90 exhibited maximal values of all examined spike traits in all years of study. Significant value of the first PCA was denoted for the grain number and the grain weight per spike, using AMMI model.
An unsymmetrical porphyrin and its metal complexes: Synthesis, spectroscopy, thermal analysis and liquid crystal properties
Authors: Zhuang Changfu , Tang Xuexin , Wang Dong , Xia Aiqing , Lian Wenhui , Shi Yuhua , Shi Tongshun
Published: October 2009

The synthesis and characterization of a new unsymmetrical porphyrin liquid crystal, 5-(4-stearoyloxyphenyl)phenyl-10,15,20-triphenylporphyrin (SPTPPH2) and its transition metal complexes (SPTPPM, M(II) = Zn, Fe, Co, Ni, Cu or Mn) are reported. Their structure and properties were studied by elemental analysis, and UV-Vis, IR, mass and 1H-HMR spectroscopy. Their luminescent properties were studied by excitation and emission spectroscopy. The quantum yields of the S1 ? S0 fluorescence were measured at room temperature. According to thermal studies, the complexes have a higher thermal stability (no decomposition until 200?C). Differential scanning calorimetry (DSC) data and an optical textural photograph, obtained using a polarizing microscope (POM), indicate that the porphyrin ligand had liquid crystalline character and that it exhibited more than one mesophase and a low-lying phase transition temperature, with transition temperatures of 19.3 and 79.4?C; the temperature range of the liquid crystal (LC) phase of the ligand was 70.1?C.
Theoretical insights into the properties of the borazine… X- complexes (X- = H, F, Cl, CN, NC or NCO)
Authors: Ghiasi Reza
Published: October 2009

The character of the NH ...X- (X- = H, F, Cl, CN, NC or NCO) interactions of borazine with anions was studied using ab initio method. The interaction energies were calculated at the B3LYP/6-311++G(d,p) level. The energetic and geometric characteristics of the complexes were compared. The 'atoms in molecules' methodology was used to analyze the electron density and to obtain atomic contributions to the total energy and charge of the systems. Natural bond orbital (NBO) analysis demonstrated the charge transfer in the study of the nature of the intermolecular interactions. The aromaticity of these compounds was predicted in light of the nucleus-independent chemical shift (NICS).
Validation of an HPLC-UV method for the determination of digoxin residues on the surface of manufacturing equipment
Authors: Todorovic Zoran , Lazic Miodrag , Veljkovic Vlada , Milenovic Dragan
Published: October 2009

In the pharmaceutical industry, an important step consists in the removal of possible drug residues from the involved equipments and areas. The cleaning procedures must be validated and methods to determine trace amounts of drugs have, therefore, to be considered with special attention. An HPLC-UV method for the determination of digoxin residues on stainless steel surfaces was developed and validated in order to control a cleaning procedure. Cotton swabs, moistened with methanol were used to remove any residues of drugs from stainless steel surfaces, and give recoveries of 85.9, 85.2 and 78.7 % for three concentration levels. The precision of the results, reported as the relative standard deviation (RSD), were below 6.3 %. The method was validated over a concentration range of 0.05-12.5 ?g mL-1. Low quantities of drug residues were determined by HPLC-UV using a Symmetry C18 column (150?4.6) mm, 5 ?m) at 20?C with an acetonitrile-water (28:72, v/v) mobile phase at a flow rate of 1.1 mL min-1, an injection volume of 100 ?L and were detected at 220 nm. A simple, selective and sensitive HPLC-UV assay for the determination of digoxin residues on stainless steel was developed, validated and applied.
Overexpression of Kinase-Negative Protein Kinase Cδ in Pancreatic β-Cells Protects Mice From Diet-Induced Glucose Intolerance and β-Cell Dysfunction
Authors: Hennige Anita M. , Ranta Felicia , Heinzelmann Isabel , Düfer Martina , Michael Diana , Braumüller Heidi , Lutz Stefan Z. , Lammers Reiner , Drews Gisela , Bosch Fatima , Häring Hans-Ulrich , Ullrich Susanne
Published: October 2009

OBJECTIVE

In vitro models suggest that free fatty acid–induced apoptotic β-cell death is mediated through protein kinase C (PKC)δ. To examine the role of PKCδ signaling in vivo, transgenic mice overexpressing a kinase-negative PKCδ (PKCδKN) selectively in β-cells were generated and analyzed for glucose homeostasis and β-cell survival.

RESEARCH DESIGN AND METHODS

Mice were fed a standard or high-fat diet (HFD). Blood glucose and insulin levels were determined after glucose loads. Islet size, cleaved caspase-3, and PKCδ expression were estimated by immunohistochemistry. In isolated islet cells apoptosis was assessed with TUNEL/TO-PRO3 DNA staining and the mitochondrial potential by rhodamine-123 staining. Changes in phosphorylation and subcellular distribution of forkhead box class O1 (FOXO1) were analyzed by Western blotting and immunohistochemistry.

RESULTS

PKCδKN mice were protected from HFD-induced glucose intolerance. This was accompanied by increased insulin levels in vivo, by an increased islet size, and by a reduced staining of β-cells for cleaved caspase-3 compared with wild-type littermates. In accordance, long-term treatment with palmitate increased apoptotic cell death of isolated islet cells from wild-type but not from PKCδKN mice. PKCδKN overexpression protected islet cells from palmitate-induced mitochondrial dysfunction and inhibited nuclear accumulation of FOXO1 in mouse islet and INS-1E cells. The inhibition of nuclear accumulation of FOXO1 by PKCδKN was accompanied by an increased phosphorylation of FOXO1 at Ser256 and a significant reduction of FOXO1 protein.

CONCLUSIONS

Overexpression of PKCδKN in β-cells protects from HFD-induced β-cell failure in vivo by a mechanism that involves inhibition of fatty acid–mediated apoptosis, inhibition of mitochondrial dysfunction, and inhibition of FOXO1 activation.
Ethnic Differences in the Relationship Between Albuminuria and Calcified Atherosclerotic Plaque
Authors: Divers Jasmin , Wagenknecht Lynne E. , Bowden Donald W. , Carr J. Jeffrey , Hightower R. Caresse , Xu Jianzhao , Langefeld Carl D. , Freedman Barry I.
Published: October 2009

OBJECTIVE

Despite higher rates of nephropathy, calcified atherosclerotic plaque is less prevalent in African Americans with diabetes relative to European Americans. We explored ethnicity-specific relationships between albuminuria and calcified plaque involving the infrarenal aorta, coronary artery, and carotid artery in 835 European American and 393 African American subjects with type 2 diabetes.

RESEARCH DESIGN AND METHODS

Generalized estimating equations with exchangeable correlation and the sandwich estimator of the variance were used to test for association between the principal component of calcified plaque in the three vascular beds and urine albumin-to-creatinine ratio (ACR).

RESULTS

Mean ± SD ages of African American and European American participants were 56.7 ± 9.6 and 61.7 ± 9.1 years, respectively, with diabetes duration of 10.4 ± 7.4 and 10.0 ± 7.3 years and median urine ACR of 17.5 and 13.4 mg/g. In African American and European American participants, respectively, median calcified plaque mass scores were 53.5 and 291 for coronary artery, 3 and 35.5 for carotid artery, and 761 and 3,237 for aorta. With adjustment for age, sex, glomerular filtration rate, and BMI, albuminuria was significantly associated with calcified plaque in European Americans (P = 3.4 × 10−8) but not in African Americans (P = 0.33), with significant ethnic interaction (P = 0.01). Ethnic differences in this relationship persisted after adjustment for blood pressure, smoking, lipids, and use of ACE inhibitors or angiotensin receptor blockers.

CONCLUSIONS

Albuminuria is strongly associated with severity of calcified plaque in European Americans with diabetes but not in African Americans. Disparities in this relationship may contribute to ethnic differences in the rates of cardiovascular disease that are observed in subjects with type 2 diabetes.
Dietary Intake of Total, Animal, and Vegetable Protein and Risk of Type 2 Diabetes in the European Prospective Investigation into Cancer and Nutrition (EPIC)-NL Study
Authors: Sluijs Ivonne , Beulens Joline W.J. , van der A Daphne L. , Spijkerman Annemieke M.W. , Grobbee Diederick E. , van der Schouw Yvonne T.
Published: October 2009

OBJECTIVE

Dietary recommendations are focused mainly on relative dietary fat and carbohydrate content in relation to diabetes risk. Meanwhile, high-protein diets may contribute to disturbance of glucose metabolism, but evidence from prospective studies is scarce. We examined the association among dietary total, vegetable, and animal protein intake and diabetes incidence and whether consuming 5 energy % from protein at the expense of 5 energy % from either carbohydrates or fat was associated with diabetes risk.

RESEARCH DESIGN AND METHODS

A prospective cohort study was conducted among 38,094 participants of the European Prospective Investigation into Cancer and Nutrition (EPIC)-NL study. Dietary protein intake was measured with a validated food frequency questionnaire. Incident diabetes was verified against medical records.

RESULTS

During 10 years of follow-up, 918 incident cases of diabetes were documented. Diabetes risk increased with higher total protein (hazard ratio 2.15 [95% CI 1.77–2.60] highest vs. lowest quartile) and animal protein (2.18 [1.80–2.63]) intake. Adjustment for confounders did not materially change these results. Further adjustment for adiposity measures attenuated the associations. Vegetable protein was not related to diabetes. Consuming 5 energy % from total or animal protein at the expense of 5 energy % from carbohydrates or fat increased diabetes risk.

CONCLUSIONS

Diets high in animal protein are associated with an increased diabetes risk. Our findings also suggest a similar association for total protein itself instead of only animal sources. Consumption of energy from protein at the expense of energy from either carbohydrates or fat may similarly increase diabetes risk. This finding indicates that accounting for protein content in dietary recommendations for diabetes prevention may be useful.
Treatment outcome of maxillary sinus cancer
Authors: Won Hye Sung , Chun Sang Hoon , Kim Bum-soo , Chung So Ryoung , Yoo Ie Ryung , Jung Chan-Kwon , Kim Yeon-Sil , Sun Dong-il , Kim Min Sik , Kang Jin-Hyoung
Published: October 2009

The standard treatment in the early stage of maxillary sinus cancer is surgical resection followed by postoperative radiation therapy. However, for locally advanced maxillary sinus cancer, a multimodality treatment approach is strongly recommended to improve the survival rate and quality of life of the patient. We determined the treatment outcomes of induction chemotherapy, concurrent chemoradiation therapy, and surgical resection for locally advanced maxillary sinus cancer. Forty-four patients with locally advanced maxillary sinus cancer, who had been treated between January 1990 and April 2008 at Kangnam St. Mary's Hospital, were retrospectively analyzed. The objective response rates were 70%, 53%, and 57% in the intra-arterial induction chemotherapy, intravenous induction chemotherapy, and concurrent chemoradiation therapy groups, respectively. The orbital preservation rates were 83%, 100%, and 75% in the intra-arterial induction chemotherapy, intravenous induction chemotherapy, and surgical resection groups, respectively. In seven of nine patients in whom the orbit could be preserved after induction chemotherapy, the primary tumors were removed completely. However, although the orbits were preserved in three patients who underwent surgical resection as a primary treatment, all three cases were confirmed to be incomplete resections. We found that active induction chemotherapy for locally advanced cancer of the maxillary sinus increased the possibility of complete resection with orbital preservation as well as tumor down-staging.
High‐Resolution Patterning of Hydrogels in Three Dimensions using Direct‐Write Photofabrication for Cell Guidance
Authors: Seidlits Stephanie K. , Schmidt Christine E. , Shear Jason B.
Published: October 2009

The development of three‐dimensional, spatially defined neuronal cultures that mimic chemical and physical attributes of native tissue is of considerable interest for various applications, including the development of tailored neuronal networks and clinical repair of damaged nerves. Here, the use of multiphoton excitation to photocrosslink protein microstructures within three‐dimensional, optically transparent hydrogel materials, such as those based on hyaluronic acid, is reported. Multiphoton excitation confines photocrosslinking to a three‐dimensional voxel with submicron spatial resolution, enabling fabrication of protein matrices with low‐ to sub‐micrometer feature sizes by scanning the focus of a laser relative to the reagent solution. These methods can be used to create complex three‐dimensional architectures that provide both chemical and topographical cues for cell culture and guidance, providing for the first time a means to direct cell adhesion and migration on size scales relevant to in vivo environments. Using this approach, guidance of both dorsal root ganglion cells (DRGs) and hippocampal neural progenitor cells (NPCs) along arbitrary, three‐dimensional paths is demonstrated.
Gonadal steroids and salivary IgA in healthy young women and men
Authors: Van Anders Sari M.
Published: October 2009

Empirical evidence from clinical, nonhuman animal, and in vitro studies point to links between immune function and gonadal steroids, including potential androgenic immunosuppression and estrogenic immunoenhancement. This study was designed to test links between steroids and one marker of mucosal humoral immunity—immunoglobulin A (IgA) in healthy individuals, to facilitate comparisons with other species and clinical populations, as there are few existing studies with healthy humans that also allow gender/sex investigations. Participants (86 women, 91 men) provided a saliva sample for measurement of testosterone (T), estradiol (E2), and IgA. Results showed that E2 was significantly and positively correlated with IgA in women, and group analyses by E2 quartile showed that this association was linear. No significant correlations or nonlinear associations were seen between T and IgA in men or women, or E2 and IgA in men. Evidence from this study indicates that IgA and E2 are significantly associated in healthy premenopausal women. Am. J. Hum. Biol. 2010. © 2009 Wiley‐Liss, Inc.
Vanadium(V)/mandelic acid initiated graft copolymerization of acrylamide onto guar gum in an aqueous medium
Authors: Srivastava Arti , Mishra Vivek , Singh Shailendra Kumar , Kumar Rajesh
Published: October 2009

The graft copolymerization reaction of acrylamide onto guar gum with a vanadium(V)/mandelic acid redox pair was carried out in an N2 atmosphere. The optimum concentrations of vanadium(V), mandelic acid, hydrogen ions, acrylamide, and guar gum for the maximum percentage of grafting were 6.0 × 10−3, 2.0 × 10−2, 55.0 × 10−2, and 20.0 × 10−2 mol/dm3 and 110.1 × 10−2 g/dm3, respectively. The optimum time and temperature of reaction were 90 min and 35°C, respectively, and during the study of [H+] variation, a prompt change in the value of the grafting parameters was observed. The maximum percentage of swelling of the graft copolymer was achieved at room temperature in 1 h. Studies of the flocculation, viscosity, and metal‐ion absorption capacity were also performed. The synthesized graft copolymer was characterized by Fourier transform infrared spectroscopy and thermogravimetric analyses, which showed that the grafted guar gum was thermally more stable than the ungrafted guar gum. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Online monitoring of the thermal degradation of POM during melt extrusion
Authors: Rajan Vipin V. , Wäber Roy , Wieser Jürgen
Published: October 2009

Because of its high stiffness, chemical resistance, and low viscosity, Poly (oxymethylene) (POM) is of high relevance for technical applications. The thermal degradation of POM during processing affects its final properties and decreases the long‐term stability. The degradation is indicated by the emission of formaldehyde (FA) gas. The aim of this study is to monitor the thermal degradation of POM online, during the melt extrusion in a co‐rotating twin screw extruder (TSE). The effect of the processing conditions on the thermal stabilisation of the POM is observed by FA emission and online viscosity measurements. The effect of processing conditions on the compounding of POM with two different FA scavengers is also studied. Fourier transform infrared (FTIR) spectroscopy is used for the online measurement of FA gas and acetyl acetone colour measurement for the offline characterisation. The online viscosity is measured by passing the melt through a slit die at constant volume flow rate. An enhanced thermal degradation is found with decreasing throughput and increasing screw speed. A good correlation between the online viscosity and offline FA measurement is observed. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Anomalous swelling of a polystyrene matrix in organic solvents
Authors: Bernardo Gabriel , Vesely Drahosh
Published: October 2009

Swelling behavior of a commercial linear polystyrene, containing a small amount (<5% wt) of mineral oil, has been studied in three different classes of organic solvents (alkanes, alcohols and carboxylic acids) using both gravimetry and light microscopy. A comparison has been made with the results presented in earlier publications using a different linear polystyrene, without mineral oil. It is shown that the polystyrene containing mineral oil absorbs much higher amounts of solvent at lower temperatures then at higher temperatures. This anomalous behavior sharply contrasts with the polystyrene without mineral oil, which at lower temperatures absorbs much less solvent. Light microscopy of the diffusion layer reveals that in the polymer with mineral oil precipitation occurs during diffusion at low temperatures, but not at high temperatures. These results clearly show that the presence of small amounts of mineral oil (in quantities below the detection limit of FTIR) can cause significant changes in the sorption behavior of polymers. These results are interpreted by pre‐existing nano‐inhomogeneities, formed by the mineral oil, limited miscibility of oil in the polymer phase and high miscibility of solvent in the oil phase. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010