bluuebunny/crossref_metadata_2025 huggingface dataset:
Climate Change Mitigation Policies in Lithuania
Authors: Konstantinaviciute Inga
Published: January 2004

The Lithuanian climate change policy has to be considered in the framework of the Convention on Climate Change. The National Strategy for Implementation of Convention was the first step in evaluating the country's impact on climate change, adapting to the Convention and foreseeing the means and measures for climate change mitigation. The paper introduces main issues related to climate change mitigation policy in Lithuania. It presents an analysis of greenhouse gas emission trends in Lithuania and surveys institutional organizations as well as stakeholder associations related to climate change issues and their role in climate policy making. The main Lithuanian international environmental obligation and Lithuanian governmental climate change mitigation policy in the energy sector are presented as well.
Environmental Policy in Poland — Current State and Perspectives of Development
Authors: Kudelko Mariusz , Suwala Wojciech
Published: January 2004

The paper describes practical and theoretical issues concerned with the current and future role of economic instruments of Polish environmental policy applicable to the areas potentially affected by serious pollution. The article lists historical and current emissions of main pollutants. The article presents a system of environmental instruments such as fees, emission standards and other measures. The economic efficiency of the instruments is analysed in respect of its future compliance with the EU regulations. The authors also consider economic instruments that are expected to enter into force in Poland in the near future. Policy objectives formulated in official documents are analysed in terms of their possible implementation.
Isolation of Buildings from Rail-Tunnel Vibration: A Review
Authors: Talbot J.P. , Hunt H.E.M.
Published: January 2004

Many buildings close to railway tunnels are built on steel springs or rubber bearings to isolate them from the ground-borne vibration. This base isolation of buildings has been employed since the 1960s and is becoming increasingly common as pressure grows to construct high-quality buildings on existing urban sites.

This paper reviews the practice and theory behind base isolation, and discusses some recent developments in modelling base-isolated buildings with a view to predicting isolation performance.
Modelling of Sound Transmission through Lightweight Elements with Stiffeners
Authors: Guigou-Carter C. , Villot M.
Published: January 2004

The sound reduction index of lightweight panels with stiffeners is calculated using the wave approach applied to an infinite thin plate line connected to periodically spaced beams and excited in flexure by a single or random (diffuse field) incident plane acoustical wave. The reaction forces and moments at the line connections are calculated from the flexural and torsional line impedance of the beams. The finite size of the panel is taken into account using a spatial windowing technique applied to the infinite panel. The case of two stiffened panels with a cavity in between and no structural connections between panels is also considered using the same approach; using SEA, the structural flanking path at the panel boundaries through any receiving structure can also be taken into account. Comparisons to measured results are given and discussed.
Diffusion and Auditorium Acoustics
Authors: Wang Ji-Qing
Published: January 2004

The prominence of diffusion in auditorium acoustics is commonly acknowledged in the literature, but neither objective measure nor subjective description indicates how it should be defined. Since we know the early sound plays an important part in the subjective success of a concert hall, several acoustical parameters for acoustical design such as EDT, tI, C80, G80, LFE, IACCE, etc. were developed in relation to the early reflections. A sound field composed of a few discrete reflections is of course non-diffuse even in a hall with plenty of surface diffusers. These diffusers may be relevant to the late reverberant sound field, which contributes to the acoustical quality of a hall and will be considered as dependent on the degree of diffusion. Compared with RT60, EDT is a better indication of perceived reverberance, and the quality of reverberant sound may not be that significant to the hall acoustics. Although the early studies of spatial impression focused on the importance of reverberant sound, recent investigations reveal that late-arriving sound from the side of the listener is more important for creating a strong sense of listener envelopment (LEV). Hence the question is: “Is diffusion over-emphasized?” After an overview on this subject, the author suggests several issues to be clarified through further investigations.
Computer Modelling of Urban Noise Propagation
Authors: Ismail M.R. , Oldham D.J.
Published: January 2004

The nature of noise propagation through the urban fabric is not well understood and this reflects the difficulty in obtaining good quality data. The most promising approach to developing urban noise prediction models is computer simulation. Reflections from building facades are a mixture of specular and diffuse. However, as the order of reflection increases the relative fraction of energy reflected purely specularly will decrease and the reflection characteristics will resemble those of the pure diffuse case. It is proposed that an appropriate approach to the development of propagation models could be based upon specular reflections for the lower orders of reflections and diffuse reflections for higher orders of reflection. An alternative statement of the above is that the specular approach would be most appropriate for modelling near field propagation whilst the diffuse approach might be more appropriate for modelling mid and far field propagation.

Two approaches to the development of diffuse prediction models have been identified. The radiosity method would allow the investigation of the effect of the disposition of individual buildings on noise propagation but would be computationally demanding if applied to large scale studies. Conversely, an approach based upon the classical diffusion equation is potentially capable of being applied to large scale studies but will not yield any local detail. It is suggested that both approaches might be suitable for incorporating into a comprehensive model for far field urban noise propagation.
Economic Consequences of Venous Thromboembolism Following Major Orthopedic Surgery
Authors: Oster Gerry , Ollendorf Daniel A , Vera-Llonch Montserrat , Hagiwara May , Berger Ariel , Edelsberg John
Published: January 2004

BACKGROUND

Venous thromboembolism (VTE) is a frequent and potentially costly complication of major orthopedic surgery.

OBJECTIVE

To estimate the economic consequences of VTE following major orthopedic surgery.

METHODS

Using a large healthcare claims database, we identified all patients who underwent total hip replacement, major knee surgery, or hip fracture repair from January 1993 to December 1998. Patients with clinical VTE (cases) were identified based on a diagnosis of deep vein thrombosis or pulmonary embolism within 90 days of surgery (index admission) and ≥1 prescription for warfarin or unfractionated heparin within 30 days of the date of initial VTE diagnosis. Each case was matched (using age and procedure type) to 2 randomly selected patients who did not have any claims for clinical VTE (matched controls). Utilization and billed charges were then examined over a 90-day period following admission. Cases were stratified based on whether VTE was first noted during the index admission or thereafter.

RESULTS

A total of 11 960 patients were identified who underwent total hip replacement, major knee surgery, or hip fracture repair (n = 3171, 3955, 4834, respectively). Over a 90-day period, 259 patients (2.2%) developed clinical VTE. Most cases (61.8%) occurred after hospital discharge. For patients with in-hospital VTE, mean length of stay for the index admission was 4.5 days longer than that of matched controls (11.1 vs 6.6); by day 90, there was a 5.4-day difference in total hospital days. Mean billed charges for the index admission were $17 552 higher ($52 037 vs $34 485); the difference rose to $18 834 by day 90 ($54 480 vs $35 646). For patients who developed clinical VTE following hospital discharge, there was a 3.4-day difference in total hospital days at day 90 (10.2 vs 6.8) as a result of readmissions for VTE; mean total billed charges at day 90 were $5765 higher ($41 411 vs $35 646)

CONCLUSION

Among patients who have undergone major orthopedic surgery, the economic consequences of VTE are substantial, regardless of the setting in which it occurs.
Therapy Switching in Patients Receiving Long-Acting Opioids
Authors: Berger Ariel , Hoffman Deborah L , Goodman Seth , Delea Thomas E , Seifeldin Raafat , Oster Gerry
Published: January 2004

BACKGROUND

Patterns of therapy switching in patients receiving long-acting opioids have not been well documented.

OBJECTIVE

To compare therapy switching among patients beginning treatment with controlled-release (CR) oxycodone, transdermal fentanyl, or CR morphine sulfate.

METHODS

Using a US healthcare claims database, we identified patients beginning treatment with CR oxycodone, transdermal fentanyl, or CR morphine sulfate between July 1, 1998, and December 31, 1999. We compiled claims for each patient for 6 months following therapy initiation and compared the incidence of therapy switching among the 3 groups. We also estimated total healthcare charges for patients who switched therapy versus those who did not.

RESULTS

We identified 1931, 668, and 449 patients beginning therapy with CR oxycodone, transdermal fentanyl, and CR morphine sulfate, respectively; 16.7%, 25.0%, and 35.9%, respectively, had cancer. For patients without cancer, rates of therapy switching at 6 months were 10.6% (CR oxycodone), 19.0% (transdermal fentanyl), and 26.0% (CR morphine sulfate); for those with cancer, rates were 23.8%, 24.6%, and 29.8%, respectively. Multivariate hazard ratios (vs CR morphine sulfate) for therapy switching in patients without cancer were 0.36 (95% CI, 0.27 to 0.47) for CR oxycodone and 0.69 (0.51 to 0.94) for transdermal fentanyl; for those with cancer, corresponding hazard ratios were 0.72 (0.50 to 1.03) and 0.76 (0.50 to 1.16). Total healthcare charges were significantly (p < 0.01) higher for patients who switched therapy than those who did not ($23 965 vs $14 299 in pts. without cancer; $58 259 vs $39 618 for those with cancer).

CONCLUSIONS

Patients without cancer who receive CR oxycodone or transdermal fentanyl are less likely to switch therapy than those receiving CR morphine sulfate. Total healthcare charges are higher for patients who switch therapy.
Nicotinic Enhancement of the Noradrenergic Inhibition of Sleep-Promoting Neurons in the Ventrolateral Preoptic Area
Authors: Saint-Mleux Benoît , Eggermann Emmanuel , Bisetti Arnaud , Bayer Laurence , Machard Danièle , Jones Barbara E. , Mühlethaler Michel , Serafin Mauro
Published: January 2004

According to multiple lines of evidence, neurons in the ventrolateral preoptic area (VLPO) that contain GABA promote sleep by inhibiting neurons of the arousal systems. Reciprocally, transmitters used by these systems, including acetylcholine (ACh) and noradrenaline (NA), exert an inhibitory action on the VLPO neurons. Because nicotine, an agonist of ACh, acts as a potent stimulant, we queried whether it might participate in the cholinergic inhibition of these sleep-promoting cells. Indeed, we found that ACh inhibits the VLPO neurons through a nicotinic, as well as a muscarinic, action. As evident in the presence of atropine, the non-muscarinic component was mimicked by epibatidine, a nonselective nicotinic ACh receptor (nAChR) agonist and was blocked by dihydro-β-erythroidine, a nonselective nAChR antagonist. It was not, however, blocked by methyllycaconitine, a selective antagonist of the α7 subtype, indicating that the action was mediated by non-α7 nAChRs. The nicotinic inhibition was attributed to a presynaptic facilitation of NA release because it persisted in the presence of tetrodotoxin and was blocked by yohimbine and RS 79948, which are both selective antagonists of α2 adrenergic receptors. Sleep-promoting VLPO neurons are thus dually inhibited by ACh through a muscarinic postsynaptic action and a nicotinic presynaptic action on noradrenergic terminals. Such dual complementary actions allow ACh and nicotine to enhance wakefulness by inhibiting sleep-promoting systems while facilitating other wake-promoting systems.
Neural Substrates Mediating Human Delay and Trace Fear Conditioning
Authors: Knight David C. , Cheng Dominic T. , Smith Christine N. , Stein Elliot A. , Helmstetter Fred J.
Published: January 2004

Previous functional magnetic resonance imaging (fMRI) studies with human subjects have explored the neural substrates involved in forming associations in Pavlovian fear conditioning. Most of these studies used delay procedures, in which the conditioned stimulus (CS) and unconditioned stimulus (UCS) coterminate. Less is known about brain regions that support trace conditioning, a procedure in which an interval of time (trace interval) elapses between CS termination and UCS onset. Previous work suggests significant overlap in the neural circuitry supporting delay and trace fear conditioning, although trace conditioning requires recruitment of additional brain regions. In the present event-related fMRI study, skin conductance and continuous measures of UCS expectancy were recorded concurrently with whole-brain blood oxygenation level-dependent (BOLD) imaging during direct comparison of delay and trace discrimination learning. Significant activation was observed within the visual cortex for all CSs. Anterior cingulate and medial thalamic activity reflected associative learning common to both delay and trace procedures. Activations within the supplementary motor area (SMA), frontal operculum, middle frontal gyri, and inferior parietal lobule were specifically associated with trace interval processing. The hippocampus displayed BOLD signal increases early in training during all conditions; however, differences were observed in hippocampal response magnitude related to the accuracy of predicting UCS presentations. These results demonstrate overlapping patterns of activation within the anterior cingulate, medial thalamus, and visual cortex during delay and trace procedures, with additional recruitment of the hippocampus, SMA, frontal operculum, middle frontal gyrus, and inferior parietal lobule during trace conditioning. These data suggest that the hippocampus codes temporal information during trace conditioning, whereas brain regions supporting working memory processes maintain the CS-UCS representation during the trace interval.
Spatial and Temporal Properties of Visual Responses in the Thalamus of the Developing Ferret
Authors: Akerman Colin J. , Grubb Matthew S. , Thompson Ian D.
Published: January 2004

Spatiotemporal patterning of neural activity is thought to influence the development of connections in the visual pathway. This patterning can arise spontaneously or through sensory experience. Here, we use a combination of natural and simple stimuli to investigate which elements of the visual environment modulate the earliest responses in the primary visual pathway of developing ferrets. Recordings were made during the first 2 weeks of visual responsiveness, which, in the ferret, overlaps with the period that the eyelids have not yet opened. Even when the eyelids are closed, both thalamic and cortical activity was found to be temporally modulated under conditions of natural visual stimulation. The modulations correlated with temporal changes in stimulus contrast but also reflected spatial structure in the visual scene. Simple stimuli were used to show that early responses to naturalistic stimuli are influenced by the localization and structure of through-the-eyelid receptive fields. The early visual responses were also characterized by substantial variability in the ability of the cells to detect stimuli of different duration and different intensity, in a temporally precise manner. These temporal and spatial properties should constrain how plasticity mechanisms interpret naturally patterned activity.
Activation of cAMP Signaling Facilitates the Morphological Maturation of Newborn Neurons in Adult Hippocampus
Authors: Fujioka Takashi , Fujioka Aya , Duman Ronald S.
Published: January 2004

Previous studies have demonstrated that activation of the cAMP cascade, including the cAMP response element-binding protein (CREB), increases the proliferation and survival of newborn neurons in adult mouse hippocampus. In the present study, we determined whether the cAMP-CREB cascade also influences the morphological maturation of newborn neurons in the subgranular zone of the hippocampus. Rolipram, a selective inhibitor of the cAMP-specific phosphodiesterase type 4, was administered to activate the cAMP cascade, and neuronal morphology was determined by analysis of Golgi-impregnated neurons in the subgranular zone of hippocampus. Rolipram administration significantly increased the number of branch points and length of dendrites relative to vehicle treatment. Increased branch number and length were accompanied by increased levels of phosphorylated CREB, the active form of this transcription factor, in immature neurons. In contrast, the morphology of Golgi-impregnated neurons was not significantly influenced by rolipram treatment in inducible transgenic mice expressing a dominant-negative mutant of CREB in hippocampus. We also tested the influence of cAMP analogs in primary hippocampal cultures and found that activation of the cAMP pathway increased and inhibition of the cAMP cascade decreased the number of branches and length of processes as observedin vivo. These findings indicate that the cAMP-CREB cascade plays an important role in the differentiation and maturation of newborn neurons in hippocampus.
The Role of AMPA Receptor Gating in the Development of High-Fidelity Neurotransmission at the Calyx of Held Synapse
Authors: Joshi Indu , Shokralla Shahira , Titis Paul , Wang Lu-Yang
Published: January 2004

During early postnatal development of auditory synapses, the decay time course of AMPA receptor (AMPAR) EPSCs accelerates markedly, but the mechanisms underlying this process remain uncertain. Using the developing calyx of Held synapse in the mouse auditory brainstem, we have examined presynaptic and postsynaptic elements that may regulate decay kinetics of AMPAR EPSCs. We found that the decay time kinetics was voltage dependent in both immature and mature synapses, being slower at positive potentials than negative potentials. By recording evoked miniature events in extracellular Ca2+or Sr2+, we revealed a significant decrease in decay time constants of EPSCs as maturation progresses. On the basis of internal and external polyamine block of AMPAR EPSCs and immunohistochemistry assays with subunit-specific antibodies, we demonstrated that the glutamate receptor (GluR) 2 subunit is virtually absent at all developmental ages. Antibody staining patterns suggest a gradual shift in subunit composition from GluR1- to GluR3/4-dominant phenotypes. Kinetic analyses of deactivation, desensitization, and recovery from desensitization in outside-out patches in response to ultrafast application of glutamate lend supportive evidence that such a shift in the gating phenotype likely accounts for the accelerated time course throughout development. Finally, by pharmacologically manipulating AMPAR gating and using simulated EPSCs to evoke action potentials, we demonstrated that rapid decay kinetics of AMPAR EPSCs is essential for this synapse to accommodate high-frequency firing without compromising spike amplitude. Hence, developmental alterations in the subunit composition likely dictate changes in the time course of AMPAR EPSCs and play an indispensable role in the refinement of high-fidelity neurotransmission at the calyx of Held synapse.
Huntingtin Bodies Sequester Vesicle-Associated Proteins by a Polyproline-Dependent Interaction
Authors: Qin Zheng-Hong , Wang Yumei , Sapp Ellen , Cuiffo Benjamin , Wanker Erich , Hayden Michael R. , Kegel Kimberly B. , Aronin Neil , DiFiglia Marian
Published: January 2004

Polyglutamine expansion in the N terminus of huntingtin (htt) causes selective neuronal dysfunction and cell death by unknown mechanisms. Truncated htt expressedin vitroproduced htt immunoreactive cytoplasmic bodies (htt bodies). The fibrillar core of the mutant htt body resisted protease treatment and contained cathepsin D, ubiquitin, and heat shock protein (HSP) 40. The shell of the htt body was composed of globules 14-34 nm in diameter and was protease sensitive. HSP70, proteasome, dynamin, and the htt binding partners htt interacting protein 1 (HIP1), SH3-containing Grb2-like protein (SH3GL3), and 14.7K-interacting protein were reduced in their normal location and redistributed to the shell. Removal of a series of prolines adjacent to the polyglutamine region in htt blocked formation of the shell of the htt body and redistribution of dynamin, HIP1, SH3GL3, and proteasome to it. Internalization of transferrin was impaired in cells that formed htt bodies. In cortical neurons of Huntington's disease patients with early stage pathology, dynamin immunoreactivity accumulated in cytoplasmic bodies. Results suggest that accumulation of a nonfibrillar form of mutant htt in the cytoplasm contributes to neuronal dysfunction by sequestering proteins involved in vesicle trafficking.
Tetraspanin Protein CD9 Is a Novel Paranodal Component Regulating Paranodal Junctional Formation
Authors: Ishibashi Tomoko , Ding Lei , Ikenaka Kazuhiro , Inoue Yoshiro , Miyado Kenji , Mekada Eisuke , Baba Hiroko
Published: January 2004

The axoglial paranodal junction is essential for the proper localization of ion channels around the node of Ranvier. The integrity of this junction is important for nerve conduction. Although recent studies have made significant progress in understanding the molecular composition of the paranodal junction, it is not known how these membrane components are distributed to the appropriate sites and interact with each other. Here we show that CD9, a member of the tetraspanin family, is present at the paranode. CD9 is concentrated in the paranode as myelination proceeds, but CD9 clusters become diffuse, associated with disruption of the paranode, in cerebroside sulfotransferase-deficient mice. Immunohistochemical and Western blot analysis showed that CD9 is distributed predominantly in the PNS. Ablation of CD9 in mutant mice disrupts junctional attachment at the paranode and alters the paranodal components contactin-associated protein (also known as Paranodin) and neurofascin 155, although the frequency of such abnormalities varies among individuals and individual axons even in the same mouse. Electron micrographs demonstrated that compact myelin sheaths were also affected in the PNS. Therefore, CD9 is a myelin protein important for the formation of paranodal junctions. CD9 also plays a role in the formation of compact myelin in the PNS.
Nitric Oxide Is a Physiological Inhibitor of Neurogenesis in the Adult Mouse Subventricular Zone and Olfactory Bulb
Authors: Moreno-López Bernardo , Romero-Grimaldi Carmen , Noval José Angel , Murillo-Carretero Maribel , Matarredona Esperanza R. , Estrada Carmen
Published: January 2004

The subventricular zone of the rodent brain retains the capacity of generating new neurons in adulthood. The newly formed neuroblasts migrate rostrally toward the olfactory bulb, where they differentiate as granular and periglomerular interneurons. The reported presence of differentiated neurons expressing the neuronal isoform of nitric oxide synthase (NOS) in the periphery of the neurogenic region and the organization of their varicose axons as a network in which the precursors are immersed raised the hypothesis that endogenous nitric oxide (NO) may participate in the control of neurogenesis in the subventricular zone. Systemic administration of the NOS inhibitors Nω-nitro-l-arginine methyl ester or 7-nitroindazole to adult mice produced a dose- and time-dependent increase in the number of mitotic cells in the subventricular zone, rostral migratory stream, and olfactory bulb, but not in the dentate gyrus of the hippocampus, without affecting apoptosis. In the subventricular zone, this effect was exerted selectively on a precursor subpopulation expressing nestin but not neuronal or glial cell-specific proteins. In addition, in the olfactory bulb, analysis of maturation markers in the newly generated neurons indicated that chronic NOS inhibition caused a delay in neuronal differentiation. Postmitotic cell survival and migration were not affected when NO production was impaired. Our results suggest that NO, produced by nitrergic neurons in the adult mouse subventricular zone and olfactory bulb, exerts a negative control on the size of the undifferentiated precursor pool and promotes neuronal differentiation.
Dopamine D1/D5 Receptor Modulates State-Dependent Switching of Soma-Dendritic Ca2+Potentials via Differential Protein Kinase A and C Activation in Rat Prefrontal Cortical Neurons
Authors: Young Clint E. , Yang Charles R.
Published: January 2004

To determine the nature of dopamine modulation of dendritic Ca2+signaling in layers V-VI prefrontal cortex (PFC) neurons, whole-cell Ca2+potentials were evoked after blockade of Na+and K+channels. Soma-dendritic Ca2+spikes evoked by suprathreshold depolarizing pulses, which could be terminated by superimposed brief intrasomatic hyperpolarizing pulses, are blocked by the L-type Ca2+channel antagonist nimodipine (1 μm). The D1/D5 receptor agonist dihydrexidine (DHX) (0.01-10 μm; 5 min) or R-(+)SKF81291 (10 μm) induced a prolonged (>30 min) dose-dependent peak suppression of these Ca2+spikes. This effect was dependent on [Ca2+]i- and protein kinase C (PKC)-dependent mechanisms because [Ca2+]ichelation by BAPTA or inhibition of PKC by bisindolymaleimide (BiM1), but not inhibition of [Ca2+]irelease with heparin or Xestospongin C, prevented the D1-mediated suppression of Ca2+spikes. Depolarizing pulses subthreshold to activating a Ca2+spike evoked a nimodipine-sensitive Ca2+“hump” potential. D1/D5 stimulation induced anN-[2-((o-bromocinamyl)amino)ethyl]-5-isoquinolinesulfonamide (H-89)- or internal PKA inhibitory peptide[5-24]-sensitive (PKA-dependent) transient (∼7 min) potentiation of the hump potential to full Ca2+spike firing. Furthermore, application of DHX in the presence of the PKC inhibitor BiM1 or internal PKC inhibitory peptide[19-36]resulted in persistent firing of full Ca2+spike bursts, suggesting that a D1/D5-PKA mechanism switches subthreshold Ca2+hump potential to fire full Ca2+spikes, which are eventually turned off by a D1/D5-Ca2+-dependent PKC mechanism. This depolarizing state-dependent, D1/D5-activated, bi-directional switching of soma-dendritic L-type Ca2+channels via PKA-dependent potentiation and PKC-dependent suppression may provide spatiotemporal regulation of synaptic integration and plasticity in PFC.
Gephyrin Is Critical for Glycine Receptor Clustering But Not for the Formation of Functional GABAergic Synapses in Hippocampal Neurons
Authors: Lévi Sabine , Logan Stephen M. , Tovar Kenneth R. , Craig Ann Marie
Published: January 2004

The role of the scaffolding protein gephyrin at hippocampal inhibitory synapses is not well understood. A previous study (Kneussel et al., 1999) reported a complete loss of synaptic clusters of the major GABAAR subunits α2 and γ2 in hippocampal neurons lacking gephyrin. In contrast, we show here that GABAAR α2 and γ2 subunits do cluster at pyramidal synapses in hippocampal cultures from gephyrin-/- mice, albeit at reduced levels compared with control neurons. Synaptic aggregation of GABAAR α1 on interneurons was identical between the culture types. Furthermore, we recorded miniature IPSCs (mIPSCs) from gephyrin-/- neurons. Although the mean mIPSC amplitude was reduced (by 23%) compared with control, the frequency of these events was unchanged. Cell surface labeling experiments indicated that gephyrin contributes, in part, to aggregation but not to insertion or stabilization of GABAAR α2 and γ2 in the plasma membrane. Thus, a major gephyrin-independent component of hippocampal inhibitory synapse development must exist. We also report that glycine receptors cluster at GABAergic synapses in a subset of hippocampal interneurons and pyramidal neurons. Unlike GABAARs, synaptic clustering of glycine receptors was completely abolished in gephyrin-/- neurons. Finally, artificial extrasynaptic aggregation of GABAAR was able to redistribute and cocluster gephyrin by a mechanism requiring a neuron-specific modification or intermediary protein. We propose a model of hippocampal inhibitory synapse development in which some GABAARs cluster at synapses by a gephyrin-independent mechanism and recruit gephyrin. This clustered gephyrin may then recruit glycine receptors, additional GABAARs, and other signal-transducing components.
Phenotype Matters: Identification of Light-Responsive Cells in the Mouse Suprachiasmatic Nucleus
Authors: Karatsoreos Ilia N. , Yan Lily , LeSauter Joseph , Silver Rae
Published: January 2004

The suprachiasmatic nucleus (SCN) of the hypothalamus is the neural locus of the circadian clock. To explore the organization of the SCN, two strains of transgenic mice, each bearing a jellyfish green fluorescent protein (GFP) reporter, were used. In one, GFP was driven by the promoter region of the mousePeriod1gene (mPer1) (Per1::GFP mouse), whereas in the other, GFP was inserted in the promoter region of calbindin-D28K-bacterial artificial chromosome (CalB::GFP mouse). In the latter mouse, GFP-containing SCN cells are immunopositive for gastrin-releasing peptide. In both mouse lines, light-inducedPer1mRNA and Fos are localized to the SCN subregion containing gastrin-releasing peptide. Double-label immunohistochemistry reveals that most gastrin-releasing peptide cells (∼70%) contain Fos after a brief light pulse. To determine the properties of SCN cells in this light-responsive region, we examined the expression of rhythmicPeriodgenes and proteins. Gastrin-releasing peptide-containing cells do not express detectable rhythms in these key components of the molecular circadian clock. The results support the view that the mammalian SCN is composed of functionally distinct cell groups, of which some are light induced and others are rhythmic with respect to clock gene expression. Furthermore, the findings suggest that gastrin-releasing peptide is a potential mediator of intercellular communication between light-induced and oscillator cells within the SCN.
The Secretory Granule-Associated Protein CAPS2 Regulates Neurotrophin Release and Cell Survival
Authors: Sadakata Tetsushi , Mizoguchi Akira , Sato Yumi , Katoh-Semba Ritsuko , Fukuda Mitsunori , Mikoshiba Katsuhiko , Furuichi Teiichi
Published: January 2004

Neurotrophins are key modulators of various neuronal functions, including differentiation, survival, and synaptic plasticity, but the molecules that regulate their secretion are poorly understood. We isolated a clone that is predominantly expressed in granule cells of postnatally developing mouse cerebellum, which turned out to be a paralog of CAPS (Ca2+-dependent activator protein for secretion), and named CAPS2. CAPS2 is enriched on vesicular structures of presynaptic parallel fiber terminals of granule cells connecting postsynaptic spines of Purkinje cell dendrites. Vesicle factions affinity-purified by the CAPS2 antibody from mouse cerebella contained significant amounts of neurotrophin-3 (NT-3), brain-derived neurotrophic factor (BDNF), and chromogranin B but not marker proteins for synaptic vesicle synaptophysin and synaptotagmin. In cerebellar primary cultures, punctate CAPS2 immunoreactivities are primarily colocalized with those of NT-3 and BDNF and near those of a postsynaptic marker, postsynaptic density-95, around dendritic arborization of Purkinje cells. Exogenously expressed CAPS2 enhanced release of exogenous NT-3 and BDNF from PC12 cells and endogenous NT-3 from cultured granule cells in a depolarization-dependent manner. Moreover, the overexpression of CAPS2 in granule cells promotes the survival of Purkinje cells in cerebellar cultures. Thus, we suggest that CAPS2 mediates the depolarization-dependent release of NT-3 and BDNF from granule cells, leading to regulation in cell differentiation and survival during cerebellar development.
Neuronal Birthdate-Specific Gene Transfer with Adenoviral Vectors
Authors: Hashimoto Mitsuhiro , Mikoshiba Katsuhiko
Published: January 2004

The multilayered structure of the cerebral cortex has been studied in detail. Early-born neurons migrate into the inner layer and late-born neurons migrate into more superficial layers, thus establishing an inside-out gradient. The progenitor cells appear to acquire layer-specific properties at the time of neuronal birth; however, the molecular mechanisms of cell-fate acquisition are still unclear, because it has been difficult to identify a cohort of birthdate-related progenitor cells. Using replication-defective adenoviral vectors, we successfully performed “pulse gene transfer” into progenitor cells in a neuronal birthdate-specific manner. When adenoviral vectors were injected into the midbrain ventricle of mouse embryos between embryonic day 10.5 (E10.5) and E14.5, the adenoviral vectors introduced a foreign gene into a specific cohort of birthdate-related progenitor cells. The virally infected cohorts developed normally into cortical neurons and formed the canonical cortical layers in an inside-out manner. This technique allows us to distinguish a cohort of birthdate-related progenitor cells from other progenitor cells with different birthdates and to introduce a foreign gene into specific subsets of cortical layers by performing adenoviral injection at specific times. This adenovirus-meditated gene transfer technique will enable us to examine the properties of each subset of progenitor cells that share the same neuronal birthdate.
Preterm Fetal Hypoxia-Ischemia Causes Hypertonia and Motor Deficits in the Neonatal Rabbit: A Model for Human Cerebral Palsy?
Authors: Derrick Matthew , Luo Ning Ling , Bregman Joanne C. , Jilling Tamas , Ji Xinhai , Fisher Kara , Gladson Candece L. , Beardsley Douglas J. , Murdoch Geoffrey , Back Stephen A. , Tan Sidhartha
Published: January 2004

Prenatal hypoxia-ischemia to the developing brain has been strongly implicated in the subsequent development of the hypertonic motor deficits of cerebral palsy (CP) in premature and full-term infants who present with neonatal encephalopathy. Despite the enormous impact of CP, there is no animal model that reproduces the hypertonia and motor disturbances of this disorder. We report a rabbit model ofin uteroplacental insufficiency, in which hypertonia is accompanied by marked abnormalities in motor control. Preterm fetuses (67-70% gestation) were subjected to sustained global hypoxia. The dams survived and gave spontaneous birth. At postnatal day 1, the pups that survived were subjected to a battery of neurobehavioral tests developed specifically for these animals, and the tests were videotaped and scored in a masked manner. Newborn pups of hypoxic groups displayed significant impairment in multiple tests of spontaneous locomotion, reflex motor activity, and the coordination of suck and swallow. Increased tone of the limbs at rest and with active flexion and extension were observed in the survivors of the preterm insult.

Histopathological studies identified a distinct pattern of acute injury to subcortical motor pathways that involved the basal ganglia and thalamus. Persistent injury to the caudate putamen and thalamus at P1 was significantly correlated with hypertonic motor deficits in the hypoxic group. Antenatal hypoxia-ischemia at preterm gestation results in hypertonia and abnormalities in motor control. These findings provide a unique behavioral model to define mechanisms and sequelae of perinatal brain injury from antenatal hypoxia-ischemia.
Persistent Progenitors at the Retinal Margin ofptc+/- Mice
Authors: Moshiri Ala , Reh Thomas A.
Published: January 2004

The hedgehog signaling pathway is a key regulator of neural development, affecting both proliferation and differentiation of neural progenitors. Sonic hedgehog (Shh) is a mitogenic factor for retinal progenitorsin vitro. To determine whether this signaling system is importantin vivofor regulating retinal progenitor proliferation, we analyzed mice with a single functional allele of the Shh receptorpatched(ptc). We found thatptc+/- mice had increased numbers of neural progenitors at every stage of retinal development that we examined. In addition, these mice had persistent progenitors at the retinal margin for up to 3 months of age, reminiscent of the ciliary marginal zone of lower vertebrates. To test whether the progenitors at the retinal margin ofptc+/- mice could be induced to regenerate retinal neurons in response to damage, we bredptc+/- mice onto a retinal degeneration background (pro23his rhodopsin transgenic) and labeled newly generated cells with combined immunohistochemistry for bromodeoxyuridine and retinal neuron and photoreceptor-specific markers. We found newly generated neurons and photoreceptors at the retinal margin inptc+/-;pro23his mice. We propose that the Shh pathway may act as a regulator of both prenatal and postnatal retinal growth.
The Impact of Suppressive Surrounds on Chromatic Properties of Cortical Neurons
Authors: Solomon Samuel G. , Peirce Jonathan W. , Lennie Peter
Published: January 2004

Stimulation of the suppressive surround of a cortical neuron affects the responsivity and tuning of the classical receptive field (CRF) on several stimulus dimensions. In V1 and V2 of macaques prepared for acute electrophysiological experiments, we explored the chromatic sensitivity of the surround and its influence on the chromatic tuning of the CRF. We studied receptive fields of single neurons with patches of drifting grating of optimal spatial frequency and orientation and variable size, modulated along achromatic or isoluminant color directions. The responses of most neurons declined as the patch was enlarged beyond the optimal size (surround suppression). In V1 the suppression evoked by isoluminant gratings was less than one-half that evoked by achromatic gratings. Consequently, many cells were most sensitive to achromatic modulation when patches just covered the CRF but were most sensitive to isoluminant modulation when patches were enlarged to cover the suppressive surround. Non-oriented neurons that were strongly chromatically opponent generally lacked suppressive surrounds. In V2 most neurons showed equal surround suppression from isoluminant gratings and achromatic gratings. This makes the relative sensitivity of V2 neurons to achromatic and isoluminant gratings mainly independent of the size of the grating. We also measured the chromatic properties of the CRF in the presence of differently colored surrounds. In neither V1 nor V2 did the surround alter the chromatic tuning of the CRF. Cortical mechanisms sensitive to chromatic contrast seem to provide little input to the suppressive surrounds of V1 neurons but substantial input to those of V2 neurons.
Functional and Genomic Changes in the Mouse Ocular Motor System in Response to Light Deprivation from Birth
Authors: McMullen Colleen A. , Andrade Francisco H. , Stahl John S.
Published: January 2004

Previous studies have suggested that abnormal visual experience early in life induces ocular motor abnormalities. The purpose of this study was to determine how visual deprivation alters the function and gene expression profile of the ocular motor system in mice. We measured the effect of dark rearing on eye movements, gene expression in the oculomotor nucleus, and contractility of isolated extraocular muscles.In vivoeye movement recordings showed decreased gains for optokinetic and vestibulo-ocular reflexes, confirming an effect of dark rearing on overall ocular motor function. Saccade peak velocities were preserved, however, arguing that the quantitative changes in these reflexes were not secondary to limitations in force generation. Using microarrays and quantitative PCR, we found that dark rearing shifted the oculomotor nucleus transcriptome to a state of delayed/arrested development. The expression of 132 genes was altered by dark rearing; these genes fit in various functional categories (signal transduction, transcription/translation control, metabolism, synaptic function, cytoskeleton), and some were known to be associated with neuronal development and plasticity. Extraocular muscle contractility was impaired by dark rearing to a greater extent than expected from thein vivoocular motility studies: changes included decreased force and shortening speed and evidence of abnormal excitability. The results indicate that normal development of the mouse ocular motor system and its muscles requires visual experience. The transcriptional pattern of arrested development may indicate that vision is required to establish the adult pattern, but it also may represent the plastic response of oculomotor nuclei to abnormal extraocular muscles.
Active Zone Localization of Presynaptic Calcium Channels Encoded by thecacophonyLocus ofDrosophila
Authors: Kawasaki Fumiko , Zou Beiyan , Xu Xia , Ordway Richard W.
Published: January 2004

Presynaptic calcium channels play a central role in chemical synaptic transmission by providing the calcium trigger for evoked neurotransmitter release. These voltage-gated calcium channels are composed of a primary structural subunit, α1, as well as auxiliary β and α2δ subunits. Our previous genetic, molecular, and functional analysis has shown that thecacophony(cac) gene encodes a primary presynaptic calcium channel α1 subunit inDrosophila. Here we report that transgenic expression of acac-encoded α1 subunit fused with enhanced green fluorescent protein efficiently rescuescaclethal mutations and allowsin vivoanalysis of calcium channel localization at active zones. The results reported here further characterize the primary role ofcac-encoded calcium channels in neurotransmitter release. In addition, these studies provide a unique genetic tool for live imaging of functional presynaptic calcium channelsin vivoand define a molecular marker for immunolocalization of other presynaptic proteins relative to active zones. These findings are expected to facilitate additional analysis of synaptic development and function in this important model system.
Improvement and Decline in Tactile Discrimination Behavior after Cortical Plasticity Induced by Passive Tactile Coactivation
Authors: Hodzic Amra , Veit Ralf , Karim Ahmed A. , Erb Michael , Godde Ben
Published: January 2004

Perceptual learning can be induced by passive tactile coactivation without attention or reinforcement. We used functional MRI (fMRI) and psychophysics to investigate in detail the specificity of this type of learning for different tactile discrimination tasks and the underlying cortical reorganization. We found that a few hours of Hebbian coactivation evoked a significant increase of primary (SI) and secondary (SII) somatosensory cortical areas representing the stimulated body parts. The amount of plastic changes was strongly correlated with improvement in spatial discrimination performance. However, in the same subjects, frequency discrimination was impaired after coactivation, indicating that even maladaptive processes can be induced by intense passive sensory stimulation.
Production and Release of Neuroprotective Tumor Necrosis Factor by P2X7Receptor-Activated Microglia
Authors: Suzuki Tomohisa , Hide Izumi , Ido Katsutoshi , Kohsaka Shinichi , Inoue Kazuhide , Nakata Yoshihiro
Published: January 2004

After a brain insult, ATP is released from injured cells and activates microglia. The microglia that are activated in this way then release a range of bioactive substances, one of which is tumor necrosis factor (TNF). The release of TNF appears to be dependent on the P2X7receptor. The inhibitors 1,4-diamino-2,3-dicyano-1,4-bis[2-amino-phenylthio]butadiene (U0126), anthra[1,9-cd]pyrazol-6(2H)-one (SP600125), and 4-(4-fluorophenyl)-2-(4-methylsulfinylphenyl)-5-(4-pyridyl)IH-imidazole (SB203580), which target MEK (mitogen-activated protein kinase kinase), JNK (c-Jun N-terminal kinase), and p38, respectively, all potently suppress the production of TNF in ATP-stimulated microglia, whereas the production of TNF mRNA is strongly inhibited by U0126 and SP600125. SB203580 did not affect the increased levels of TNF mRNA but did prevent TNF mRNA from accumulating in the cytoplasm. The ATP-provoked activation of JNK and p38 [but not extracellular signal-regulated kinase (ERK)] could be inhibited by brilliant blue G, a P2X7receptor blocker, and by genistein and 4-amino-5-(4-chlorophenyl)-7-(t-butyl)pyrazolo[3,4-d]pyrimidine, which are general andsrc-family-specific tyrosine kinase inhibitors, respectively. Most important, we found that treatment of the microglia in neuron-microglia cocultures with the P2X7agonist 2′-3′-O-(benzoyl-benzoyl) ATP led to significant reductions in glutamate-induced neuronal cell death, and that either TNF-α converting enzyme inhibitor or anti-TNF readily suppressed the protective effect implied by this result. Together, these findings indicate that both ERK and JNK are involved in the regulation of TNF mRNA expression, that p38 is involved in the nucleocytoplasmic transport of TNF mRNA, and that a PTK (protein tyrosine kinase), possibly a member of thesrcfamily, acts downstream of the P2X7receptor to activate JNK and p38. Finally, our data suggest that P2X7receptor-activated microglia protect neurons against glutamate toxicity primarily because they are able to release TNF.
Production of Resurgent Current in NaV1.6-Null Purkinje Neurons by Slowing Sodium Channel Inactivation with β-Pompilidotoxin
Authors: Grieco Tina M. , Raman Indira M.
Published: January 2004

Voltage-gated tetrodotoxin-sensitive sodium channels of Purkinje neurons produce “resurgent” current with repolarization, which results from relief of an open-channel block that terminates current flow at positive potentials. The associated recovery of sodium channels from inactivation is thought to facilitate the rapid firing patterns characteristic of Purkinje neurons. Resurgent current appears to depend primarily on NaV1.6 α subunits, because it is greatly reduced in “med”mutant mice that lack NaV1.6. To identify factors that regulate the susceptibility of α subunits to open-channel block, we voltage clamped wild-type andmedPurkinje neurons before and after slowing conventional inactivation with β-pompilidotoxin (β-PMTX). β-PMTX increased resurgent current in wild-type neurons and induced resurgent current inmedneurons. Inmedcells, the resurgent component of β-PMTX-modified sodium currents could be selectively abolished by application of intracellular alkaline phosphatase, suggesting that, like in NaV1.6-expressing cells, the open-channel block of NaV1.1 and NaV1.2 subunits is regulated by constitutive phosphorylation. These results indicate that the endogenous blocker exists independently of NaV1.6 expression, and conventional inactivation regulates resurgent current by controlling the extent of open-channel block. In Purkinje cells, therefore, the relatively slow conventional inactivation kinetics of NaV1.6 appear well adapted to carry resurgent current. Nevertheless, NaV1.6 is not unique in its susceptibility to open-channel block, because under appropriate conditions, the non-NaV1.6 subunits can produce robust resurgent currents.