bluuebunny/crossref_metadata_2025 huggingface dataset:
Regulation of Gene Expression by Chronic Morphine and Morphine Withdrawal in the Locus Ceruleus and Ventral Tegmental Area
Authors: McClung Colleen A. , Nestler Eric J. , Zachariou Venetia
Published: June 2005

Morphine dependence is associated with long-term adaptive changes in the brain that involve gene expression. Different behavioral effects of morphine are mediated by different brain regions, for example, the locus ceruleus (LC), a noradrenergic nucleus, is implicated in physical dependence and withdrawal, whereas the ventral tegmental area (VTA), a dopaminergic nucleus, contributes to rewarding and locomotor responses to the drug. However, the global changes in gene expression that occur in these brain regions after morphine exposure and during withdrawal remain unknown. Using DNA microarray analysis in both mice and rats, we now characterize gene expression changes that occur in these brain regions with chronic morphine and antagonist-precipitated withdrawal. In the LC, numerous genes display common regulation between mouse and rat, including tyrosine hydroxylase, prodynorphin, and galanin. Furthermore, we identify clusters of genes that are regulated similarly by chronic morphine and by withdrawal, as well as clusters that show opposite regulation under these two conditions. Interestingly, most gene expression changes that occur in the VTA in response to chronic morphine are different from those seen in the LC, but the gene expression patterns in the two brain regions are very similar after withdrawal. In addition, we examined two genes (prodynorphin and FK506 binding protein 5) that are strongly regulated by chronic morphine or morphine withdrawal in the LC for their role in regulating withdrawal-associated behaviors. Inhibition of either protein profoundly affects withdrawal responses, demonstrating that the genes identified in this study have important functional roles in mediating opiate-induced behaviors.
Three Channels of Corticothalamic Communication during Locomotion
Authors: Sirota Mikhail G. , Swadlow Harvey A. , Beloozerova Irina N.
Published: June 2005

We studied the flow of corticothalamic (CT) information from the motor cortex of the cat during two types of locomotion: visually guided (cortex dependent) and unguided. Spike trains of CT neurons in layers V (CT5s) and VI (CT6s) were examined. All CT5s had fast-conducting axons (<2 ms conduction time), and nearly all showed step-phase-related activity (94%), sensory receptive fields (100%), and spontaneous activity (100%). In contrast, conduction times along CT6 axons were much slower, with bimodal peaks occurring at 6 and 32 ms. Remarkably, almost none of the slowest conducting CT6s showed step-related activity, sensory receptive fields, or spontaneous activity. As a group, these enigmatic neurons were all but silent. Some of the CT6s with moderately conducting axons showed step-related behavior (35%), and this response was more precisely timed than that of the CT5s. We propose distinct functional roles for these diverse corticothalamic populations.
Encoding and Decoding of Dendritic Excitation during Active States in Pyramidal Neurons
Authors: Williams Stephen R.
Published: June 2005

Neocortical neurons spontaneously fire action potentials during active network states; how are dendritic synaptic inputs integrated into the ongoing action potential output pattern of neurons? Here, the efficacy of barrages of simulated EPSPs generated at known dendritic sites on the rate and pattern of ongoing action potential firing is determined using multisite whole-cell recording techniques from rat layer 5 neocortical pyramidal neuronsin vitro. Under quiescent conditions, the somatic impact of proximal (253 ± 15 μm from soma;n= 28) dendritic barrages of simulated EPSPs was 4.7-fold greater than identical barrages of EPSPs generated from distal (572 ± 13 μm from soma) sites. In contrast, barrages of proximal simulated EPSPs enhanced the rate of ongoing action potential firing, evoked by somatic simulated EPSPs, by only 1.6-fold more than distal simulated EPSPs. This relationship was apparent across a wide frequency range of action potential firing (6-22 Hz) and dendritic excitation (100-500 Hz). The efficacy of distal dendritic EPSPs was formed by the recruitment of active dendritic processes that transformed the ongoing action potential firing pattern, promoting action potential burst firing. Paired recordings (n= 42) revealed that patterns of action potential firing generated by concerted somatic and distal dendritic excitation reliably and powerfully drove postsynaptic excitation as a result of enhanced reliability of transmitter release during bursts of action potential firing. During active states, therefore, distal excitatory synaptic inputs decisively control the excitatory synaptic output of layer 5 neocortical pyramidal neurons and so powerfully influence network activity in the neocortex.
Involvement of the Central Thalamus in the Control of Smooth Pursuit Eye Movements
Authors: Tanaka Masaki
Published: June 2005

During maintenance of smooth pursuit eye movements, the brain must keep track of pursuit velocity to reconstruct target velocity from motion of retinal images. Although a recent study showed that corollary discharge signals through the thalamus to the cortex are used for internal monitoring of saccades, it remains unknown whether signals in the thalamus also contribute to monitoring and on-line regulation of smooth pursuit. The present study sought possible roles of the thalamocortical pathways in pursuit by recording activities of single thalamic neurons and by analyzing the effects of local inactivation. Data showed that many neurons in the ventrolateral thalamus exhibited directional modulation during pursuit. Most neurons discharged before or during initiation of pursuit, and the firing rate was proportional to the speed of target motion in a preferred direction. When the tracking target was extinguished briefly during maintenance of pursuit, these neurons continued firing, indicating that they carried extra-retinal, eye movement signals. The majority of neurons showed no change in activity around the time of small catch-up saccades during pursuit but responded transiently to large (16°) memory-guided saccades in the preferred pursuit direction. Local inactivation of the recording sites did not alter pursuit latency but reduced eye velocity modestly during initiation and maintenance of ipsiversive pursuit. The results suggest that the central thalamus lies within pathways that regulate and monitor smooth pursuit eye movements.
Intravesicular Localization and Exocytosis of α-Synuclein and its Aggregates
Authors: Lee He-Jin , Patel Smita , Lee Seung-Jae
Published: June 2005

α-Synuclein (α-syn), particularly in its aggregated forms, is implicated in the pathogenesis of Parkinson's disease and other related neurological disorders. However, the normal biology of α-syn and how it relates to the aggregation of the protein are not clearly understood. Because of the lack of the signal sequence and its predominant localization in the cytosol, α-syn is generally considered exclusively an intracellular protein. Contrary to this assumption, here, we show that a small percentage of newly synthesized α-syn is rapidly secreted from cells via unconventional, endoplasmic reticulum/Golgi-independent exocytosis. Consistent with this finding, we also demonstrate that a portion of cellular α-syn is present in the lumen of vesicles. Importantly, the intravesicular α-syn is more prone to aggregation than the cytosolic protein, and aggregated forms of α-syn are also secreted from cells. Furthermore, secretion of both monomeric and aggregated α-syn is elevated in response to proteasomal and mitochondrial dysfunction, cellular defects that are associated with Parkinson's pathogenesis. Thus, intravesicular localization and secretion are part of normal life cycle of α-syn and might also contribute to pathological function of this protein.
Propriospinal Circuitry Underlying Interlimb Coordination in Mammalian Quadrupedal Locomotion
Authors: Juvin Laurent , Simmers John , Morin Didier
Published: June 2005

Soon after birth, freely moving quadrupeds can express locomotor activity with coordinated forelimb and hindlimb movements. To investigate the neural mechanisms underlying this coordination, we used an isolated spinal cord preparation from neonatal rats. Under bath-applied 5-HT,N-methyl-d,l-aspartate (NMA), and dopamine (DA), the isolated cord generates fictive locomotion in which homolateral cervicolumbar extensor motor bursts occur in phase opposition, as does bursting in homologous (left-right) extensor motoneurons. This coordination corresponded to a walking gait monitored with EMG recordings in the freely behaving animal. Functional decoupling of the cervical and lumbar generatorsin vitroby sucrose blockade at the thoracic cord level revealed independent rhythmogenic capabilities with similar cycle frequencies in the two locomotor regions. When the cord was partitioned at different thoracic levels and 5-HT/NMA/DA was applied to the more caudal compartment, the ability of the lumbar generators to drive their cervical counterparts increased with the proportion of chemically exposed thoracic segments. Blockade of synaptic inhibition at the lumbar level caused synchronous bilateral lumbar rhythmicity that, surprisingly, also was able to impose bilaterally synchronous bursting at the unblocked cervical level. Furthermore, after a midsagittal section from spinal segments C1 to T7, and during additional blockade of cervical synaptic inhibition, the cord exposed to 5-HT/NMA/DA continued to produce a coordinated fictive walking pattern similar to that observed in control. Thus, in the newborn rat, a caudorostral propriospinal excitability gradient appears to mediate interlimb coordination, which relies more on asymmetric axial connectivity (both excitatory and inhibitory) between the lumbar and cervical generators than on differences in their inherent rhythmogenic capacities.
Distinct Contributions of Hippocampal NMDA and AMPA Receptors to Encoding and Retrieval of One-Trial Place Memory
Authors: Bast Tobias , da Silva Bruno M. , Morris Richard G. M.
Published: June 2005

Allocentric place memory may serve to specify the context of events stored in human episodic memory. Recently, our laboratory demonstrated that, analogous to event-place associations in episodic memory, rats could associate, within one trial, a specific food flavor with an allocentrically defined place in an open arena. Encoding, but not retrieval, of such flavor-place associations required hippocampal NMDA receptors; retrieval depended on hippocampal AMPA receptors. This might have partly reflected the contributions of these receptors to encoding and retrieval of one-trial place, rather than flavor-place, memory. Therefore, the present study developed a food-reinforced arena paradigm to study encoding and retrieval of one-trial allocentric place memory in rats; memory relied on visuospatial information and declined with increasing retention delay, still being significant after 6 h, the longest delay tested (experiments 1 and 2). Hippocampal infusion of the NMDA receptor antagonistd-AP-5 blocked encoding without affecting retrieval; hippocampal infusion of the AMPA receptor antagonist CNQX impaired retrieval (experiment 3). Finally, we confirmed that thed-AP-5 infusions selectively blocked induction of long-term potentiation, a form of synaptic plasticity, whereas CNQX impaired fast excitatory transmission, at perforant-path dentate gyrus synapses in the dorsal hippocampusin vivo(experiment 4). Our results support that encoding, but not retrieval, of one-trial allocentric place memory requires the NMDA receptor-dependent induction of hippocampal synaptic plasticity, whereas retrieval depends on AMPA receptor-mediated fast excitatory hippocampal transmission. The contributions of hippocampal NMDA and AMPA receptors to one-trial allocentric place memory may be central to episodic memory and related episodic-like forms of memory in rats.
The Sensory Cortical Representation of the Human Penis: Revisiting Somatotopy in the Male Homunculus
Authors: Kell Christian A. , von Kriegstein Katharina , Rösler Alexander , Kleinschmidt Andreas , Laufs Helmut
Published: June 2005

Pioneering mapping studies of the human cortex have established the notion of somatotopy in sensory representation, which transpired into Penfield and Rasmussen's famous sensory homunculus diagram. However, regarding the primary cortical representation of the genitals, classical and modern findings appear to be at odds with the principle of somatotopy, often assigning it to the cortex on the mesial wall. Using functional neuroimaging, we established a mediolateral sequence of somatosensory foot, penis, and lower abdominal wall representation on the contralateral postcentral gyrus in primary sensory cortex and a bilateral secondary somatosensory representation in the parietal operculum.
Redundant Localization Mechanisms of RIM and ELKS inCaenorhabditis elegans
Authors: Deken Scott L. , Vincent Rose , Hadwiger Gayla , Liu Qiang , Wang Zhao-Wen , Nonet Michael L.
Published: June 2005

Active zone proteins play a fundamental role in regulating neurotransmitter release and defining release sites. The functional roles of active zone components are beginning to be elucidated; however, the mechanisms of active zone protein localization are unknown. Studies have shown that glutamine, leucine, lysine, and serine-rich protein (ELKS), a recently defined member of the active zone complex, acts to localize the active zone protein Rab3a-interacting molecule (RIM) and regulates synaptic transmission in cultured neurons. Here, we test the function of ELKSin vivo. Like mammalian ELKS,Caenorhabditis elegansELKS is an active zone protein that directly interacts with the postsynaptic density-25/Discs large/zona occludens (PDZ) domain of RIM. However, RIM protein localizes in the absence of ELKS andvice versa. In addition,elksmutants exhibit neither the behavioral nor the physiological defects associated withunc-10RIM mutants, indicating that ELKS is not a critical component of theC. elegansrelease machinery. Interestingly, expression of the soluble PDZ domain of RIM disrupts ELKS active zone targeting, suggesting a tight association between the two proteinsin vivo. RIM truncations containing only the PDZ and C2A domains target to release sites in an ELKS-dependent manner. Together, these data identify ELKS as a new member of theC. elegansactive zone complex, define the role of ELKS in synaptic transmission, and characterize the relationship between ELKS and RIMin vivo. Furthermore, they demonstrate that multiple different protein-protein interactions redundantly anchor both ELKS and RIM to active zones and implicate novel proteins in the formation of the active zone.
The Nonpeptide Calcitonin Gene-Related Peptide Receptor Antagonist BIBN4096BS Lowers the Activity of Neurons with Meningeal Input in the Rat Spinal Trigeminal Nucleus
Authors: Fischer Michael Jochen Marco , Koulchitsky Stanislav , Messlinger Karl
Published: June 2005

Calcitonin gene-related peptide (CGRP) has been suggested to play a major role in the pathogenesis of migraines and other primary headaches. CGRP may be involved in the control of neuronal activity in the spinal trigeminal nucleus (STN), which integrates nociceptive afferent inputs from trigeminal tissues, including intracranial afferents. The activity of STN neurons is thought to reflect the activity of central trigeminal nociceptive pathways causing facial pain and headaches in humans.

In a rat model of meningeal nociception, single neuronal activity in the STN was recorded. All units had receptive fields located in the exposed parietal dura mater. Heat and cold stimuli were repetitively applied to the dura in a fixed pattern of ramps and steps. The nonpeptide CGRP receptor antagonist BIBN4096BS was topically applied onto the exposed dura or infused intravenously.

BIBN4096BS (300 μg/kg, i.v.) reduced spontaneous activity by ∼30%, the additional dose of 900 μg/kg intravenously by ∼50% of the initial activity, whereas saline had no effect. The activity evoked by heat ramps was also reduced after BIBN4096BS (900 μg/kg, i.v.) by ∼50%. Topical administration of BIBN4096BS (1 mm) did not significantly change the spontaneous neuronal activity within 15 min.

We conclude that the endogenous release of CGRP significantly contributes to the maintenance of spontaneous activity in STN neurons. Blockade of CGRP receptors, possibly at central and peripheral sites, may therefore be an effective way to decrease nociceptive transmission. This may offer a new therapeutic strategy for the treatment of facial pain and primary headaches.
Long-Term Potentiation Is Impaired in Middle-Aged Rats: Regional Specificity and Reversal by Adenosine Receptor Antagonists
Authors: Rex Christopher S. , Kramár Enikö A. , Colgin Laura L. , Lin Bin , Gall Christine M. , Lynch Gary
Published: June 2005

Memory loss in humans begins early in adult life and progresses thereafter. It is not known whether these losses reflect the failure of cellular processes that encode memory or disturbances in events that retrieve it. Here, we report that impairments in hippocampal long-term potentiation (LTP), a form of synaptic plasticity associated with memory, are present by middle age in rats but only in select portions of pyramidal cell dendritic trees. Specifically, LTP induced with theta-burst stimulation in basal dendrites of hippocampal field CA1 decayed rapidly in slices prepared from 7- to 10-month-old rats but not in slices from young adults. There were no evident age-related differences in LTP in the apical dendrites. Both the adenosine A1receptor antagonist 8-cyclopentyl-1,3-dipropylxanthine and a positive AMPA receptor modulator (ampakine) offset age-related LTP deficits. Adenosine produced greater depression of synaptic responses in middle-aged versus young adult slices and in basal versus apical dendrites. These results were not associated with variations in A1receptor densities and may instead reflect regional and age-related differences in adenosine clearance. Pertinent to this, brief applications of A1receptor antagonists immediately after theta stimulation fully restored LTP in middle-aged rats. We hypothesize that the build-up of extracellular adenosine during theta activity persists into the postinduction period in the basal dendrites of middle-aged slices and thereby activates the A1receptor-dependent LTP reversal effect. Regardless of the underlying mechanism, the present results provide a candidate explanation for memory losses during normal aging and indicate that, with regard to plasticity, different segments of pyramidal neurons age at different rates.
Perceptual Fusion and Stimulus Coincidence in the Cross-Modal Integration of Speech
Authors: Miller Lee M. , D'Esposito Mark
Published: June 2005

Human speech perception is profoundly influenced by vision. Watching a speaker's mouth movements significantly improves comprehension, both for normal listeners in noisy environments and especially for the hearing impaired. A number of brain regions have been implicated in audiovisual speech tasks, but little evidence distinguishes them functionally. In an event-related functional magnetic resonance imaging study, we differentiate neural systems that evaluate cross-modal coincidence of the physical stimuli from those that mediate perceptual binding. Regions consistently involved in perceptual fusion per se included Heschl's gyrus, superior temporal sulcus, middle intraparietal sulcus, and inferior frontal gyrus. Successful fusion elicited activity biased toward the left hemisphere, although failed cross-modal binding recruited regions in both hemispheres. A broad network of other areas, including the superior colliculus, anterior insula, and anterior intraparietal sulcus, were more involved with evaluating the spatiotemporal correspondence of speech stimuli, regardless of a subject's perception. All of these showed greater activity to temporally offset stimuli than to audiovisually synchronous stimuli. Our results demonstrate how elements of the cross-modal speech integration network differ in their sensitivity to physical reality versus perceptual experience.
Noradrenaline Transmission within the Ventral Bed Nucleus of the Stria Terminalis Is Critical for Fear Behavior Induced by Trimethylthiazoline, a Component of Fox Odor
Authors: Fendt Markus , Siegl Stephanie , Steiniger-Brach Björn
Published: June 2005

The bed nucleus of the stria terminalis (BNST) is involved in the mediation of fear behavior in rats. A previous study of our laboratory demonstrated that temporary inactivation of the BNST blocks fear behavior induced by exposure to trimethylthiazoline (TMT), a component of fox odor. The present study investigates whether noradrenaline release within the BNST is critical for TMT-induced fear behavior. First, we confirmed previous studies showing that the ventral BNST is the part of the BNST that receives the densest noradrenaline innervation. Second, usingin vivomicrodialysis, we showed that noradrenaline release within the BNST is strongly increased during TMT exposure, and that this increase can be blocked by local infusions of the α2-receptor blocker clonidine. Third, using intracerebral injections, we showed that clonidine injections into the ventral BNST, but not into neighboring brain sites, completely blocked TMT-induced potentiation of freezing behavior. The present data clearly show that the noradrenergic innervation of the ventral BNST is important for the full expression of behavioral signs of fear to the predator odor TMT.
Fasciclin II Signals New Synapse Formation through Amyloid Precursor Protein and the Scaffolding Protein dX11/Mint
Authors: Ashley James , Packard Mary , Ataman Bulent , Budnik Vivian
Published: June 2005

Cell adhesion molecules (CAMs) have been universally recognized for their essential roles during synapse remodeling. However, the downstream pathways activated by CAMs have remained mostly unknown. Here, we used theDrosophilalarval neuromuscular junction to investigate the pathways activated by Fasciclin II (FasII), a transmembrane CAM of the Ig superfamily, during synapse remodeling. We show that the ability of FasII to stimulate or to prevent synapse formation depends on the symmetry of transmembrane FasII levels in the presynaptic and postsynaptic cell and requires the presence of the fly homolog of amyloid precursor protein (APPL). In turn, APPL is regulated by direct interactions with the PDZ (postsynaptic density-95/Discs large/zona occludens-1)-containing protein dX11/Mint/Lin-10, which also regulates synapse expansion downstream of FasII. These results provide a novel mechanism by which cell adhesion molecules are regulated and provide fresh insights into the normal operation of APP during synapse development.
Anesthetics Change the Excitation/Inhibition Balance That Governs Sensory Processing in the Cat Superior Colliculus
Authors: Populin Luis C.
Published: June 2005

The superior colliculus (SC) is a midbrain structure that plays a central role in the integration of information from different sensory modalities and the generation of orienting responses. Its normal function is thought to be governed by a strictly held balance between excitation and inhibition. This hypothesis was tested by recording from the same single units in the SC of cats before the injection of anesthetics, while anesthetics took effect, and after the injections during recovery. Sodium pentobarbital and ketamine, two agents commonly used in sensory physiology, were used. The results show a plethora of dose-dependent and nonlinear effects: the magnitude of evoked responses, receptive field properties, first spike latency, and bimodal integration were affected by both anesthetics in all units tested. Notably, prominent facilitation was observed at low levels of anesthesia, and inhibitory responses were changed into excitatory. Overall, the results challenge a fundamental tenet of sensory physiology: anesthesia, while decreasing single-unit responsiveness, leaves unaltered basic physiological properties.
The Role of Thalamic Inputs in Surround Receptive Fields of Barrel Neurons
Authors: Kwegyir-Afful Ernest E. , Bruno Randy M. , Simons Daniel J. , Keller Asaf
Published: June 2005

Controversy exists regarding the relative roles of thalamic versus intracortical inputs in shaping the response properties of cortical neurons. In the whisker-barrel system, this controversy centers on the mechanisms determining the receptive fields of layer IV (barrel) neurons. Whereas principal whisker-evoked responses are determined by thalamic inputs, the mechanisms responsible for adjacent whisker (AW) responses are in dispute. Here, we took advantage of the fact that lesions of the spinal trigeminal nucleus interpolaris (SpVi) significantly reduce the receptive field size of neurons in the ventroposterior thalamus. We reasoned that if AW responses are established by these thalamic inputs, brainstem lesions would significantly reduce the receptive field sizes of barrel neurons. We obtained extracellular single unit recordings from barrel neurons in response to whisker deflections from control rats and from rats that sustained SpVi lesions. After SpVi lesions, the receptive field of both excitatory and inhibitory barrel neurons decreased significantly in size, whereas offset/onset response ratios increased. Response magnitude decreased only for inhibitory neurons. All of these findings are consistent with the hypothesis that AW responses are determined primarily by direct thalamic inputs and not by intracortical interactions.
Sexual Dimorphism of Short-Wavelength Photoreceptors in the Small White Butterfly,Pieris rapae crucivora
Authors: Arikawa Kentaro , Wakakuwa Motohiro , Qiu Xudong , Kurasawa Masumi , Stavenga Doekele G.
Published: June 2005

The eyes of the female small white butterfly,Pieris rapae crucivora, are furnished with three classes of short-wavelength photoreceptors, with sensitivity peaks in the ultraviolet (UV) (λmax= 360 nm), violet (V) (λmax= 425 nm), and blue (B) (λmax= 453 nm) wavelength range. Analyzing the spectral origin of the photoreceptors, we isolated three novel mRNAs encoding opsins corresponding to short-wavelength-absorbing visual pigments. We localized the opsin mRNAs in the retinal tissue and found that each of the short-wavelength-sensitive photoreceptor classes exclusively expresses one of the opsin mRNAs. We, accordingly, termed the visual pigments PrUV, PrV, and PrB, respectively. The eyes of the male small white butterfly also use three classes of short-wavelength photoreceptors that equally uniquely express PrUV, PrV, and PrB. However, whereas the spectral sensitivities of the male photoreceptors with PrUV and PrB closely correspond to those of the female, the male photoreceptor expressing PrV has a double-peaked blue (dB) spectral sensitivity, strongly deviating from the spectral sensitivity of the female V photoreceptor. The male eyes contain a pigment that distinctly fluoresces under blue-violet as well as UV excitation light. It coexists with the dB photoreceptors and presumably acts as a spectral filter with an absorbance spectrum peaking at 416 nm. The narrow-band spectral sensitivity of the male dB photoreceptors probably evolved to improve the discrimination of the different wing colors of male and femaleP. rapae crucivorain the short-wavelength region of the spectrum.
Mash1andMath3Are Required for Development of Branchiomotor Neurons and Maintenance of Neural Progenitors
Authors: Ohsawa Ryosuke , Ohtsuka Toshiyuki , Kageyama Ryoichiro
Published: June 2005

Basic helix-loop-helix (bHLH) transcription factors are known to play important roles in neuronal determination and differentiation. However, their exact roles in neural development still remain to be determined because of the functional redundancy. Here, we examined the roles of neural bHLH genesMash1andMath3in the development of trigeminal and facial branchiomotor neurons, which derive from rhombomeres 2-4. InMath3-null mutant mice, facial branchiomotor neurons are misspecified, and both trigeminal and facial branchiomotor neurons adopt abnormal migratory pathways. InMash1;Math3double-mutant mice, trigeminal and facial branchiomotor neurons are severely reduced in number partly because of increased apoptosis. In addition, neurons with migratory defects are intermingled over the midline from either side of the neural tube. Furthermore, oligodendrocyte progenitors of rhombomere 4 are reduced in number. In the absence ofMash1andMath3, expression of Notch signaling components is severely downregulated in rhombomere 4 and neural progenitors are not properly maintained, which may lead to intermingling of neurons and a decrease in oligodendrocyte progenitors. These results indicate thatMash1andMath3not only promote branchiomotor neuron development but also regulate the subsequent oligodendrocyte development and the cytoarchitecture by maintaining neural progenitors through Notch signaling.
Developmental Changes in Diffusion Anisotropy Coincide with Immature Oligodendrocyte Progression and Maturation of Compound Action Potential
Authors: Drobyshevsky Alexander , Song Sheng-Kwei , Gamkrelidze Georgi , Wyrwicz Alice M. , Derrick Matthew , Meng Fan , Li Limin , Ji Xinhai , Trommer Barbara , Beardsley Douglas J. , Luo Ning Ling , Back Stephen A. , Tan Sidhartha
Published: June 2005

Disruption of oligodendrocyte lineage progression is implicated in the white-matter injury that occurs in cerebral palsy. We have previously published a model in rabbits consistent with cerebral palsy. Little is known of normal white-matter development in perinatal rabbits. Using a multidimensional approach, we defined the relationship of oligodendrocyte lineage progression and functional maturation of axons to structural development of selected cerebral white-matter tracts as determined by diffusion tensor imaging (DTI). Immunohistochemical studies showed that late oligodendrocyte progenitors appear at gestational age 22 [embryonic day 22 (E22)], whereas immature oligodendrocytes appear at E25, and both increase rapidly with time (∼13 cells/mm2/d) until the onset of myelination. Myelination began at postnatal day 5 (P5) (E36) in the internal capsule (IC) and at P11 in the medial corpus callosum (CC), as determined by localization of sodium channels and myelin basic protein. DTI of the CC and IC showed that fractional anisotropy (FA) increased rapidly between E25 and P1 (E32) (∼11% per day) and plateaued (<5% per day) after the onset of myelination. Postnatal maturation of the compound action potential (CAP) showed a developmental pattern similar to FA, with a rapid rise between E29 and P5 (in the CC, 18% per day) and a slower rise from P5 to P11 (in the CC, <5% per day). The development of immature oligodendrocytes after E29 coincides with changes in FA and CAP area in both the CC and IC. These findings suggest that developmental expansion of immature oligodendrocytes during the premyelination period may be important in defining structural and functional maturation of the white matter.
F2‐Isoprostanes as Markers of Oxidant Stress: An Overview
Authors: Musiek Erik S. , Morrow Jason D.
Published: June 2005

The isoprostanes are a unique series of prostaglandin‐like compounds formed in vivo via a non‐enzymatic mechanism involving the free radical–initiated peroxidation of arachidonic acid. This unit summarizes selected aspects regarding current knowledge of these compounds and their value as markers of oxidative injury. Novel aspects related to the biochemistry of isoprostane formation are discussed and methods by which these compounds can be analyzed and quantified are summarized. A considerable portion of this unit examines the utility of F2‐isoprostanes as markers of oxidant injury in vitro and in vivo. Numerous studies carried out over the past decade have shown that these compounds are extremely accurate measures of lipid peroxidation in animals and humans and have illuminated the role of oxidant injury in a number of human diseases.
A Timely Reassessment of Early Prediction in the Bioavailability of Orally Administered Drugs
Authors: Larsen Tim , Link Andreas
Published: June 2005

Rule of thumb: Deciding the fate of drug candidates after an estimate of oral bioavailability depends on how heavily the selection parameters are applied. A retrospective analysis of medications on the market has shown that lipophilicity, percent polar surface area, and the number of H‐bond donors are properties that have remained relatively constant over the years, and are clearly the most important physicochemical determinants.
Experimental analysis of viscoelastic properties in carbon black‐filled natural rubber compounds
Authors: Sajjayanukul Tibhawan , Saeoui Pongdhorn , Sirisinha Chakrit
Published: June 2005

Processability and viscoelastic properties of natural rubber (NR) compounds filled with different carbon black loadings and types were investigated with the use of a steady shear rheometer, namely, the Mooney viscometer, and an oscillatory rheometer, namely, the Rubber Process Analyser (RPA2000). It was found that the type and amount of carbon black strongly influence the viscoelastic properties of rubber compounds. Both the dilution effect and filler transient network are responsible for the viscoelastic properties, depending on the vulcanization state. In the case of uncured compounds, the damping factor of the uncured NR decreases with increasing black loading. This is attributed to the reduction of mobilized rubber content in the compound (or the dilution effect). However, in the case of the cured NR vulcanizates, the filler transient network is the dominant factor governing the damping factor of the vulcanizate. With increasing black loading, the damping factor of the vulcanizate clearly increases. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 2197–2203, 2005
Pb2+ binding by polyaspartyl polymers and their application to Pb2+ removal from glycyrrhizin
Authors: Sun Bo , Mi Zhen‐Tao , Ouyang Jie , An Gang , Song Xiao‐Kai
Published: June 2005

Polyaspartate is an excellent Pb2+‐binding agent in comparison with some polyaspartamide derivatives with different side chains, in that it possesses a higher Pb2+ uptake and a lower Pb2+ equilibrium concentration. Equilibrium sorption data for Pb2+ on polyaspartate can be well fitted with the Freundlich and Langmuir models. Experimental results show that a crosslinked polyaspartate hydrogel is superior to poly(acrylic acid)‐based resins and polystyrene‐based chelating resins. IR spectra and X‐ray photoelectron spectra reveal that the polyaspartate hydrogel binds Pb2+ by both an ion‐exchange mechanism and a chelating mechanism. The polyaspartate hydrogel is also an effective agent for the removal of Pb2+ from glycyrrhizin. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 2215–2220, 2005
Synthesis and polymerization of the acrylamide derivatives of fatty compounds
Authors: Eren Tarik , Kusefoglu Selim H.
Published: June 2005

The Ritter reaction of plant oil triglycerides (such as soybean and sunflower oil) with acrylonitrile was used to introduce acrylamide functionality on the triglyceride. Acrylonitrile and triglycerides were reacted in the presence of H2SO4, and acrylamide derivatives were obtained in yields of 45 and 50% for sunflower oil and soybean oil, respectively. Radical initiated copolymerization of the acrylamide derivatives of the triglycerides with styrene produced semirigid polymers. Characterization of new monomers and polymers was done by 1H‐NMR, 13C‐NMR, IR, and MS. The swelling behavior of the crosslinked network polymers was determined in different solvents. Glass transiton temperature (Tg) of the cured resin was also determined by differential scanning calorimeter to be 40°C for soybean based polymer and 30°C for sunflower‐based polymer. Homo‐ and copolymerization behavior of acrylamide derivatives of methyl oleate (MOA) and methyl 10‐undecenoate (MUA) were also investigated. The reactivity ratios of these monomers with respect to styrene were determined by the Fineman–Ross method using 1H‐NMR spectroscopic data. The reactivity ratios were rsty = 1.776; rmoa = 0512 for MOA, and rsty = 1.142; rmua = 0.507 for MUA, respectively. Photopolymerization behaviors of MOA and MUA were also investigated using the photoDSC technique and the rate of polymerization of MUA is higher than that of MOA under the same conditions. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 2264–2272, 2005
Synthesis and characterization of chitosan derivatives carrying galactose residues
Authors: Zhang Can , Ping Qineng , Ding Ya
Published: June 2005

A series of water‐soluble chitosan derivatives, carrying galactose residues, were synthesized by using an alternative method in which the galactose groups were introduced into amino groups of the derivatives. First, hydroxyethyl chitosan (HECS) and hydroxypropyl chitosan (HPCS) were synthesized under alkaline conditions by using chitosan and propylene or chitosan and ClCH2CH2OH as the starting materials, respectively. Then lactobionic acid was added into the systems so as to form galactosylated HECS (Gal‐HECS) and galactosylated HPCS (Gal‐HPCS) with substitution degrees of 53 and 47%, respectively. Lactosaminated HPCS (Lac‐HPCS) and Lactosaminated HECS (Lac‐HECS) were obtained with substitution degrees of 42 and 38%, respectively, by the reductive amination of the mixtures of lactose and HECS or lactose and HPCS with potassium borohydride present in the reaction. The chemical structures of new chitosan derivatives were characterized by FTIR, 1H NMR, 13C NMR, and elemental analysis. Some physical properties were also analyzed by wide angle X‐ray diffraction (WAXD) and differential scanning calorimetry (DSC). The novel chitosan derivatives carrying galactose residues may be used as additives for hepatic targeting delivery. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 2161–2167, 2005
Responses of the silkworm tyramine receptor to 2‐phenylethylamines and 5‐phenyloxazoles
Authors: Ohta Hiroto , Khan Md. Anwar Arfien , Nagai Idumi , Umemoto Natsuko , Hamasaki Tomohiro , Ozoe Yoshihisa
Published: June 2005

Tyramine (TA), a biogenic amine, attenuates intracellular cAMP production by acting on its receptor in insects. Several non‐biogenic amines were examined for their actions on native and heterologously expressed silkworm TA receptors. 5‐(4‐Hydroxyphenyl)oxazole, which showed an attenuating effect on cAMP production in silkworm‐head membranes, did not attenuate forskolin‐stimulated cAMP production in HEK‐293 cells expressing the silkworm TA receptor, although the compound bound to the cloned receptor. 2‐Phenylethylamines (2‐PEAs), which showed positive and negative effects on cAMP production in silkworm‐head membranes, inhibited [3H]TA binding to the cloned TA receptor. 2‐Chloro‐2‐(4‐chlorophenyl)ethylamine was the most potent inhibitor of [3H]TA binding among the 2‐PEAs tested, with an IC50 of 30.4 nM. This compound acted as an antagonist and abolished TA‐attenuation of forskolin‐stimulated cAMP production in the cloned TA receptor. The discrepancy in the effects of the non‐biogenic amines on the native and cloned TA receptors remains to be further examined. A newly synthesized 2‐PEA, 2‐chloro‐2‐(4‐hydroxyphenyl)ethylamine, attenuated forskolin‐stimulated cAMP production in the cloned TA receptor, indicating that the para‐hydroxy group is important for the agonist action. Arch. Insect Biochem. Physiol. 59:150–160, 2005. © 2005 Wiley‐Liss, Inc.
Soluble interleukin‐1 receptor accessory protein ameliorates collagen‐induced arthritis by a different mode of action from that of interleukin‐1 receptor antagonist
Authors: Smeets R. L. , Joosten L. A. B. , Arntz O. J. , Bennink M. B. , Takahashi N. , Carlsen H. , Martin M. U. , van den Berg W. B. , van de Loo F. A. J.
Published: June 2005

Objective

To discern the mode of interleukin‐1 (IL‐1) inhibition of soluble IL‐1 receptor accessory protein (sIL‐1RAcP) by comparison with IL‐1 receptor antagonist (IL‐1Ra) in arthritis.

Methods

Adenoviral vectors encoding either sIL‐1RAcP or IL‐1Ra were administered systemically before onset of collagen‐induced arthritis in DBA/1 mice. Anti–bovine type II collagen IgG and IL‐6 were quantified in serum. Proliferative response of splenic T cells was determined in the presence of sIL‐1RAcP or IL‐1Ra. The effect on IL‐1 inhibition of recombinant sIL‐1RAcP and IL‐1Ra was further examined in vitro, using NF‐κB luciferase reporter cell lines. Quantitative polymerase chain reaction was used to determine the relative messenger RNA expression of the IL‐1 receptors.

Results

Adenoviral overexpression of both sIL‐1RAcP and IL‐1Ra resulted in amelioration of the collagen‐induced arthritis. Both IL‐1 antagonists reduced the circulating levels of antigen‐specific IgG2a antibodies, but only IL‐1Ra was able to inhibit lymphocyte proliferation. By using purified lymphocyte populations derived from NF‐κB reporter mice, we showed that sIL‐1RAcP inhibits IL‐1–induced NF‐κB activity in B cells but not T cells, whereas IL‐1Ra inhibited IL‐1 on both cell types. A study in a panel of NF‐κB luciferase reporter cells showed that the sIL‐1RAcP inhibits IL‐1 signaling on cells expressing either low levels of membrane IL‐1RAcP or high levels of IL‐1RII.

Conclusion

We show that the sIL‐1RAcP ameliorated experimental arthritis without affecting T cell immunity, in contrast to IL‐1Ra. Our results provide data in support of receptor competition by sIL‐1RAcP as an explanation for the different mode of IL‐1 antagonism in comparison with IL‐1Ra.
Intracellular free radical production in synovial T lymphocytes from patients with rheumatoid arthritis
Authors: Remans P. H. J. , van Oosterhout M. , Smeets T. J. M. , Sanders M. , Frederiks W. M. , Reedquist K. A. , Tak P. P. , Breedveld F. C. , van Laar J. M.
Published: June 2005

Objective

To investigate the cellular and molecular sources of oxidative stress in patients with rheumatoid arthritis (RA) through analysis of the production of reactive oxygen species (ROS) in synovium.

Methods

Cytochemical procedures based on the 3,3′‐diaminobenzidine (DAB)–Mn2+ deposition technique were used on unfixed cryostat sections of synovium from RA patients and rheumatic disease controls. For immunophenotyping, sections were incubated, fixed, and stained with fluorescein isothiocyanate–labeled antibodies. Fluorescence‐activated cell sorter analysis of the ROS‐reactive dye 6‐carboxy‐2′,7′‐dichlorodihydrofluorescein diacetate‐di(acetoxymethyl ester) was used to measure intracellular ROS in T lymphocytes from peripheral blood and synovial fluid. To determine which enzymes produced ROS, different inhibitors were tested.

Results

Large quantities of DAB precipitated in the majority of RA synovial T lymphocytes, indicative of intracellular ROS production. These ROS‐producing T lymphocytes were observed throughout the synovium. Polymerization of DAB was observed to a lesser extent in other forms of chronic arthritis, but was absent in osteoarthritis. DAB staining of cytospin preparations of purified RA synovial fluid T cells confirmed the presence of ROS‐producing cells. One of the ROS involved appeared to be H2O2, since catalase suppressed intracellular ROS production. Superoxide dismutase, which uses superoxide as a substrate to form H2O2, diphenyleneiodonium (an inhibitor of NADPH oxidase), NG‐monomethyl‐L‐arginine (an inhibitor of nitric oxide synthesis), nordihydroguaiaretic acid (an inhibitor of lipoxygenase), and rotenone (an inhibitor of mitochondrial ROS production) failed to suppress ROS production.

Conclusion

Our findings show that chronic oxidative stress observed in synovial T lymphocytes is not secondary to exposure to environmental free radicals, but originates from intracellularly produced ROS. Additionally, our data suggest that one of the intracellularly generated ROS is H2O2, although the oxidase(s) involved in its generation remains to be determined.
Invasiveness of fibroblast‐like synoviocytes is an individual patient characteristic associated with the rate of joint destruction in patients with rheumatoid arthritis
Authors: Tolboom Tanja C. A. , van der Helm‐Van Mil Annette H. M. , Nelissen Rob G. H. H. , Breedveld Ferdinand C. , Toes René E. M. , Huizinga Tom W. J.
Published: June 2005

Objective

Rheumatoid arthritis (RA) is characterized by inflammation and destruction of synovial joints. Fibroblast‐like synoviocytes (FLS) harvested from synovial tissue of patients with RA can invade normal human cartilage in severe combined immunodeficient (SCID) mice and Matrigel basement membrane matrix in vitro. This study was undertaken to investigate the association of these in vitro characteristics with disease characteristics in patients with RA.

Methods

Synovial tissue samples from 72 RA and 49 osteoarthritis (OA) patients were obtained. Samples of different joints were collected from 7 patients with RA. The FLS invasiveness in Matrigel was studied, and the intraindividual and interindividual differences were compared. From the patients with FLS who exhibited the most extreme differences in in vitro ingrowth (most and least invasive FLS), radiographs of the hands and feet were collected and scored according to the Sharp/van der Heijde method to determine the relationship between in vitro invasion data and estimated yearly joint damage progression.

Results

FLS from patients with RA were more invasive than FLS from patients with OA (P < 0.001). The mean intraindividual variation in FLS invasion was much less than the mean interindividual variation (mean ± SD 1,067 ± 926 and 3,845 ± 2,367 for intraindividual and interindividual variation, respectively; P = 0.035), which shows that the level of FLS invasion is a patient characteristic. The mean ± SEM Sharp score on radiographs of the hands or feet divided by the disease duration was 4.4 ± 1.1 units per year of disease duration in patients with the least invasive FLS (n = 9), which was much lower compared with the 21.8 ± 3.1 units per year of disease duration in patients with the most invasive FLS (n = 9) (P < 0.001).

Conclusion

The ex vivo invasive behavior of FLS from RA patients is associated with the rate of joint destruction and is a patient characteristic, given the much smaller intraindividual than interindividual FLS variation.