Age-related defects in spatial memory are correlated with defects in the late phase of hippocampal long-term potentiation in vitro and are attenuated by drugs that enhance the cAMP signaling pathway

To study the physiological and molecular mechanisms of age-related memory loss, we assessed spatial memory in C57BL/B6 mice from different age cohorts and then measured in vitro the late phase of hippocampal long-term potentiation (L-LTP). Most young mice acquired the spatial task, whereas only a minority of aged mice did. Aged mice not only made significantly more errors but also exhibited greater individual differences. Slices from the hippocampus of aged mice exhibited significantly reduced L-LTP, and this was significantly and negatively correlated with errors in memory. Because L-LTP depends on cAMP activation, we examined whether drugs that enhanced cAMP would attenuate the L-LTP and memory defects. Both dopamine D1/D5 receptor agonists, which are positively coupled to adenylyl cyclase, and a cAMP phosphodiesterase inhibitor ameliorated the physiological as well as the memory defects, consistent with the idea that a cAMP-protein kinase A-dependent signaling pathway is defective in age-related spatial memory loss.

Long-term potentiation is reduced in mice that are doubly mutant in endothelial and neuronal nitric oxide synthase

Nitric oxide (NO) has been implicated in hippocampal long-term potentiation (LTP), but LTP is normal in mice with a targeted mutation in the neuronal form of NO synthase (nNOS-). LTP was also normal in mice with a targeted mutation in endothelial NOS (eNOS-), but LTP in stratum radiatum of CA1 was significantly reduced in doubly mutant mice (nNOS-/eNOS-). By contrast, LTP in stratum oriens was normal in the doubly mutant mice. These results provide the first genetic evidence that NOS is involved in LTP in stratum radiatum and suggest that the neuronal and endothelial forms can compensate for each other in mice with a single mutation. They further suggest that there is also a NOS-independent component of LTP in stratum radiatum and that LTP in stratum oriens is largely NOS independent.

Nitric oxide as a retrograde messenger during long-term potentiation in hippocampus

Nitric oxide (NO) is widespread in the nervous system and is thought to play a role in a variety of different neuronal functions, including learning and memory (see other chapters, this volume). A number of behavioral studies have indicated that NO is involved in several types of learning such as motor learning (Yanagihara and Kondo, 1996), avoidance learning (Barati and Kopf, 1996; Myslivecek et al., 1996), olfactory learning (Okere et. al., 1996; Kendrick et al., 1997), and spatial learning (Holscher et al., 1995; Yamada et al., 1996) (for review of earlier papers see Hawkins, 1996). Moreover, NO is thought to be involved in neuronal plasticity contributing to these different types of learning in different brain areas including the cerebellum (chapter by R. Tsien, this volume) and hippocampus. In this chapter we review evidence on the role of NO in long-term potentiation (LTP), a type of synaptic plasticity in hippocampus that is believed to contribute to declarative forms of learning such as spatial learning.

A selective role of calcineurin aalpha in synaptic depotentiation in hippocampus

Pharmacological studies have suggested that long-term potentiation (LTP) and long-term depression (LTD) and depotentiation, three forms of synaptic plasticity in the hippocampus, require the activity of the phosphatase calcineurin. At least two different isoforms of calcineurin are found in the central nervous system. To investigate whether all of these forms of synaptic plasticity require the same isoforms of calcineurin, we have examined LTD, depotentiation, and LTP in mice lacking the predominant calcineurin isoform in the central nervous system, Aalpha-/- mice. Depotentiation was abolished completely whereas neither LTD nor LTP were affected. These studies provide genetic evidence that the Aalpha isoform of calcineurin is important for the reversal of LTP in the hippocampus and indicate that depotentiation and LTD operate through somewhat different molecular mechanisms.

Elliptic flow of charged particles in Pb-Pb collisions at sqrt[S(NN)] = 2.76 TeV

We report the first measurement of charged particle elliptic flow in Pb-Pb collisions at sqrt[S(NN)] =2.76 TeV with the ALICE detector at the CERN Large Hadron Collider. The measurement is performed in the central pseudorapidity region (|η|<0.8) and transverse momentum range 0.2<p t<5.0 GeV/c. The elliptic flow signal v₂, measured using the 4-particle correlation method, averaged over transverse momentum and pseudorapidity is 0.087 ± 0.002(stat) ± 0.003(syst) in the 40%-50% centrality class. The differential elliptic flow v₂ p t reaches a maximum of 0.2 near p t =3 GeV/c. Compared to RHIC Au-Au collisions at sqrt[S(NN)] 200 GeV, the elliptic flow increases by about 30%. Some hydrodynamic model predictions which include viscous corrections are in agreement with the observed increase.

Centrality dependence of the charged-particle multiplicity density at midrapidity in Pb-Pb collisions at sqrt[s(NN)] = 2.76 TeV

The centrality dependence of the charged-particle multiplicity density at midrapidity in Pb-Pb collisions at sqrt[s_{NN}]=2.76  TeV is presented. The charged-particle density normalized per participating nucleon pair increases by about a factor of 2 from peripheral (70%-80%) to central (0%-5%) collisions. The centrality dependence is found to be similar to that observed at lower collision energies. The data are compared with models based on different mechanisms for particle production in nuclear collisions.

Protein kinase C-mediated functional regulation of dopamine transporter is not achieved by direct phosphorylation of the dopamine transporter protein

Dopaminergic neurotransmission is terminated by the action of the presynaptic dopamine transporter (DAT). It mediates Na(+)/Cl(-) -dependent re-uptake of extracellular dopamine (DA) into the cell, and is regarded as a major regulatory mechanism for synaptic transmission. Previous works have documented that protein kinase C (PKC) activator or inhibitor alters DA uptake by DAT, suggesting that PKC phosphorylation plays an important regulatory mechanism in DAT function. Based on the existence of consensus amino acid sequences for PKC phosphorylation, it has been postulated that PKC regulation of DAT is mediated by the direct phosphorylation of DAT protein. In this study, we try to discover whether the functional regulation of DAT by PKC is due to direct phosphorylation of DAT. The PKC null mutant hDAT, where all putative PKC phosphorylation sites are eliminated, has been constructed by the replacement of serine/threonine residues with glycines. The mutation itself showed no effect on the functional activities of DAT. The DA uptake activity of PKC null mutant was equivalent to those of wild-type hDAT (80-110% of wild-type). Phorbol ester activation of PKC inhibited DA uptake of wild-type hDAT by 35%, and staurosphorine blocked the effect of phorbol ester on DA uptake. The same phenomena was observed in PKC null mutant DAT, although no significant phosphorylation was observed by PKC activation. Confocal microscopic analysis using EGFP-fused DAT revealed that the activation of PKC by phorbol ester elicited fluorescent DAT to be internalized into the intracellular space both in wild-type and PKC null mutant DAT in a similar way. These results suggest that PKC-mediated regulation of DAT function is achieved in an indirect manner, such as phosphorylation of a mediator protein or activation of a clathrin-mediated pathway.

Higher harmonic anisotropic flow measurements of charged particles in Pb-Pb collisions at sqrt(s(NN)) = 2.76 TeV

We report on the first measurement of the triangular v3, quadrangular v4, and pentagonal v5 charged particle flow in Pb-Pb collisions at sqrt(s(NN)) = 2.76  TeV measured with the ALICE detector at the CERN Large Hadron Collider. We show that the triangular flow can be described in terms of the initial spatial anisotropy and its fluctuations, which provides strong constraints on its origin. In the most central events, where the elliptic flow v2 and v3 have similar magnitude, a double peaked structure in the two-particle azimuthal correlations is observed, which is often interpreted as a Mach cone response to fast partons. We show that this structure can be naturally explained from the measured anisotropic flow Fourier coefficients.

Charged-particle multiplicity density at midrapidity in central Pb-Pb collisions at sqrt[S(NN)] = 2.76 TeV

The first measurement of the charged-particle multiplicity density at midrapidity in Pb-Pb collisions at a center-of-mass energy per nucleon pair √ S NN = 2.76 TeV is presented. For an event sample corresponding to the most central 5% of the hadronic cross section, the pseudorapidity density of primary charged particles at midrapidity is 1584 ± 4(stat) ± 76(syst), which corresponds to 8.3 ± 0.4(syst) per participating nucleon pair. This represents an increase of about a factor 1.9 relative to pp collisions at similar collision energies, and about a factor 2.2 to central Au-Au collisions at √ S NN = 2.76 TeV. This measurement provides the first experimental constraint for models of nucleus-nucleus collisions at LHC energies.

Induction of proinflammatory mediators requires activation of the TRAF, NIK, IKK and NF-kappaB signal transduction pathway in astrocytes infected with Escherichia coli

Escherichia coli is associated with inflammation in the brain. To investigate whether astrocytes are involved in E. coil-induced inflammation, we assessed the levels of expression of proinflammatory mediators produced by E. coli-infected astrocytes. E. coli infection in primary human astrocytes and cell lines increased expression of the CXC chemokine IL-8/GRO-alpha, the CC chemokine MCP-1, TNF-alpha, and iNOS. E. coli infection activated p65/p50 heterodimeric NF-kappaB and concurrently decreased the signals of IkappaBalpha. Blocking the NF-kappaB signals by IkappaBalpha-superrepressor-containing retrovirus or antisense p50 oligonucleotide transfection resulted in down-regulation of expression of the proinflammatory mediators. Furthermore, superrepressors of IkappaBalpha, IkappaB kinase (IKK) or NF-kappaB inducing kinase (NIK) inhibited the up-regulated expression of the downstream target genes of NF-kappaB such as IL-8 and MCP-1, and superrepressors of TNF receptor-associated factor (TRAF)2 and TRAF5 also inhibited expression of the E. coli-induced target genes of NF-kappaB. These results indicate that proinflammatory mediators such as the CXC chemokine IL-8/GRO-alpha, the CC chemokine MCP-1, TNF-alpha, and iNOS can be expressed in E. coli-infected astrocytes via an NF-kappaB pathway, suggesting that these mediators may contribute to inflammation in the brain, including infiltration of inflammatory cells.

The translocation and involvement of protein kinase C in mossy fiber-CA3 long-term potentiation in hippocampus of the rat brain

The detailed mechanisms underlying long-term potentiation (LTP) are not known. In hippocampal CA1, translocation of protein kinase C (PKC) activity from cytosol to membrane and subsequent phosphorylation of growth associated protein (GAP)-43 have been demonstrated to be critical events for the maintenance phase of LTP. LTP in mossy fiber (MF)-CA3 pathway and the Schaffer collateral/commissural (SC)-CA1 pathway differ in a number of ways: SC-CA1 LTP depends on NMDA receptors while MF-CA3 LTP does not, and SC-CA1 LTP is primarily postsynaptic while MF-CA3 LTP is primarily presynaptic. The role of PKC in MF-CA3 LTP has not been studied. We investigated the role of PKC in CA3 and show that PKC inhibitors prevent LTP, but that PKC activators produce a reversible synaptic potentiation, indicating that PKC activation is an essential but not sufficient component of LTP in CA3. Then using antibodies against specific PKC isozymes we have determined the membrane vs. cytosolic distribution of various PKC isozymes in slices subjected to low or tetanic stimulation, or perfused with phorbol esters (PDAc). Compared with control, LTP and PDAc slices show greater PKC-alpha and -epsilon immunoreactivity in the membrane fraction, indicating that both LTP and phorbol ester treatment induce translocation of PKC-alpha and -epsilon from cytosol to membrane. However, with PKC-beta and PKC-gamma the only detectable translocation from cytosol to membrane was in the phorbol ester-treated slices. Thus, while phorbol ester treatment causes translocation of PKC-alpha, -beta, -gamma and -epsilon, the only detectable translocation associated with CA3 LTP is that of PKC-alpha and -epsilon.

Protein kinase C activation is necessary but not sufficient for induction of long-term potentiation at the synapse of mossy fiber-CA3 in the rat hippocampus

The involvement of protein kinase C in long-term potentiation was investigated in the mossy fiber-CA3 pathway in an in vitro slice preparation of rat hippocampus. Tetanic stimulation induced stable long-term potentiation in the mossy fiber-CA3 pathway which was not affected by N-methyl-D-aspartate receptor antagonists. Long-term potentiation was not induced in the presence of a protein kinase C inhibitor, sphingosine. Application of 1 microM phorbol-12, 13-diacetate, an activator of protein kinase C, potentiated the synaptic response by about 400% and this potentiation was completely reversible upon washing. Sphingosine blocked the potentiation when it was applied before protein kinase C activation by phorbol-12, 13-diacetate. However, sphingosine had no effect on the potentiation when it was applied after the synaptic response was potentiated to a plateau following phorbol-12,13-diacetate perfusion. Long-term potentiation and phorbol ester-induced potentiation were not additive when phorbol-12,13-diacetate was applied after induction of long-term potentiation, suggesting that long-term potentiation and phorbol-12, 13-diacetate activate the same protein kinase C pool. The enhanced response caused by phorbol-12,13-diacetate returned to the long-term potentiation level after wash-out of phorbol-12,13-diacetate. Thus the cellular changes underlying long-term potentiation are long-lasting or permanent, while those caused by phorbol-12,13-diacetate are not. However, if tetanic stimulation was induced during prolonged phorbol-12,13-diacetate application (1 h), a potentiation similar in amplitude to long-term potentiation was induced but the population response returned to the control pre-long-term potentiation level after 2 h of washing. The potentiation following tetanic stimulation during prolonged application of phorbol-12,13-diacetate was blocked in the presence of D-2-amino-5-phosphonovaleric acid, a N-methyl-D-aspartate receptor antagonist. Thus, in the presence of phorbol esters the N-methyl-D-aspartate-independent long-term potentiation is occluded but a transient potentiation appears, presumably due to hyperexcitability and activation of N-methyl-D-aspartate receptors in recurrent pathways of area CA3. Normal N-methyl-D-aspartate-independent long-term potentiation could be induced after the 2 h washout period and now was maintained. In conclusion, protein kinase C activation is essential but not sufficient for long-term potentiation in the mossy fiber-CA3 pathway and when stimulated by application of phorbol esters produces a large and reversible synaptic potentiation. These investigations show that long-term potentiation in CA3 is a complex event involving several steps, and that activation of protein kinase C is only one of them.

Developmental stage-dependent self-regulation of embryonic cortical precursor cell survival and differentiation by leukemia inhibitory factor

Cortical precursor cells secrete soluble factors for their own survival and self-renewal. We show here that neural precursor cells isolated from embryonic rat cortices abundantly secrete leukemia inhibitory factor (LIF) and express its receptor components, gp130 and LIF receptor. LIF signaling is responsible for cortical precursor cell survival. As described previously, LIF caused astrocytic differentiation of cultured embryonic cortical precursor cells. LIF-mediated survival and astrocytic differentiation of cortical precursor cells were differentially regulated, depending on the developmental ages of embryos from which cortical precursors were isolated. LIF did not enhance the survival of cortical precursor cells isolated from later embryos (embryonic day 16, E16). Moreover, LIF-mediated astrocytic differentiation was not observed in early (E12) cortical precursors. Inhibition studies revealed that Janus-activated kinase/signal transducer and activator of transcription and phosphatidylinositol 3 kinase/Akt pathways participate in both the LIF-mediated effects. However, mitogen-activated protein kinase, another signal pathway activated by LIF, was specifically responsible for astrocytic differentiation. These findings collectively indicate that precursor cells self-regulate the sequential processes of brain development, such as early maintenance of the precursor cell population and later differentiation into astrocytes, via common LIF signaling.

Measurement of the Inelastic Proton-Proton Cross Section at sqrt[s]=13 TeV with the ATLAS Detector at the LHC

This Letter presents a measurement of the inelastic proton-proton cross section using 60  μb^{-1} of pp collisions at a center-of-mass energy sqrt[s] of 13 TeV with the ATLAS detector at the LHC. Inelastic interactions are selected using rings of plastic scintillators in the forward region (2.07<|η|<3.86) of the detector. A cross section of 68.1±1.4  mb is measured in the fiducial region ξ=M_{X}^{2}/s>10^{-6}, where M_{X} is the larger invariant mass of the two hadronic systems separated by the largest rapidity gap in the event. In this ξ range the scintillators are highly efficient. For diffractive events this corresponds to cases where at least one proton dissociates to a system with M_{X}>13  GeV. The measured cross section is compared with a range of theoretical predictions. When extrapolated to the full phase space, a cross section of 78.1±2.9  mb is measured, consistent with the inelastic cross section increasing with center-of-mass energy.

Estimation of environmental force for the haptic interface of robotic surgery

BACKGROUND

The success of a telerobotic surgery system with haptic feedback requires accurate force-tracking and position-tracking capacity of the slave robot. The two-channel force-position control architecture is widely used in teleoperation systems with haptic feedback for its better force-tracking characteristics and superior position-tracking capacity for the maximum stability margin. This control architecture, however, requires force sensors at the end-effector of the slave robot to measure the environment force. However, it is difficult to attach force sensors to slave robots, mainly due to their large size, insulation issues and also large currents often flowing through the end-effector for incision or cautery of tissues.

METHODS

This paper provides a method to estimate the environment force, using a function parameter matrix and a recursive least-squares method. The estimated force is used to feed back the force information to the surgeon through the control architecture without involving the force sensors.

RESULTS

The simulation and experimental results verify the efficacy of the proposed method. The force estimation error is negligible and the slave device successfully tracks the position of the master device while the stability of the teleoperation system is maintained.

CONCLUSIONS

The developed method allows practical haptic feedback for telerobotic surgery systems in the two-channel force-position control scheme without the direct employment of force sensors at the end-effector of the slave robot.

J/ψ suppression at forward rapidity in Pb-Pb collisions at √s(NN) = 2.76 TeV

The ALICE experiment has measured the inclusive J/ψ production in Pb-Pb collisions at √s(NN) = 2.76 TeV down to zero transverse momentum in the rapidity range 2.5 < y < 4. A suppression of the inclusive J/ψ yield in Pb-Pb is observed with respect to the one measured in pp collisions scaled by the number of binary nucleon-nucleon collisions. The nuclear modification factor, integrated over the 0%-80% most central collisions, is 0.545 ± 0.032(stat) ± 0.083(syst) and does not exhibit a significant dependence on the collision centrality. These features appear significantly different from measurements at lower collision energies. Models including J/ψ production from charm quarks in a deconfined partonic phase can describe our data.

Charge separation relative to the reaction plane in Pb-Pb collisions at sqrt[s(NN)] = 2.76 TeV

Measurements of charge-dependent azimuthal correlations with the ALICE detector at the LHC are reported for Pb-Pb collisions at sqrt[s(NN)] = 2.76 TeV. Two- and three-particle charge-dependent azimuthal correlations in the pseudorapidity range |η| < 0.8 are presented as a function of the collision centrality, particle separation in pseudorapidity, and transverse momentum. A clear signal compatible with a charge-dependent separation relative to the reaction plane is observed, which shows little or no collision energy dependence when compared to measurements at RHIC energies. This provides a new insight for understanding the nature of the charge-dependent azimuthal correlations observed at RHIC and LHC energies.

Synthesis and in vitro antibacterial activity of 3-[N-methyl-N-(3-methyl-1,3-thiazolium-2-yl)aminolmethyl cephalosporin derivatives

The new cephalosporins having N-linked quarternary ammonium salt at C-3 position were prepared from the reaction of 2-methylimino-3-methyl-1,3-thiazoline derivatives with cephalosporins. Also antimicrobial activities of those compounds were determined.

Raman spectroscopy study of isolated double-walled carbon nanotubes with different metallic and semiconducting configurations

A double-walled carbon nanotube (DWNT) provides the simplest system to study the interaction between concentric layers in carbon nanotubes. The inner and outer walls of a DWNT can be metallic (M) or semiconducting (S), and each of the four possible configurations (M@M, M@S, S@S, S@M) has different electronic properties. Here we report, for the first time, detailed Raman spectroscopy experiments carried out on individual DWNTs, where both concentric tubes are measured under resonance conditions, in order to understand the dependence of their electronic and optical properties according to their configuration. Interestingly, for the three DWNTs that were studied, the inner-outer tube distance (e.g., 0.31-0.33 nm) was less than the interlayer spacing in graphite. We believe these results have important implications in the fabrication of electronic devices using different types of S and M tubular interconnects.

Initial validation of a novel rat model of vasculogenic erectile dysfunction with generalized atherosclerosis

Although rats have been widely used in evaluating various causes of vasculogenic erectile dysfunction (VED), the atherosclerotic rat model has seldom been tried probably due to its inherent tolerance to a cholesterol diet. To enhance endothelial sensitivity to cholesterol diet, we tested the effects of transient interruption of nitric oxide synthase on atherogenesis induced by cholesterol diet in a rat model. Rats with atherosclerosis (AS group) received 1% cholesterol diet for 6 weeks. During the initial 2 weeks, they drank water that contained N(G)-nitro-L-arginine methyl ester (L-NAME) (3 mg/ml). After 6 weeks, we carried out histologic and hemodynamic evaluation to confirm pelvic atherosclerosis and erectile dysfunction, respectively, and the results were compared with those of cholesterol only (Chol) group and normal control (C) group. Compared to the C or Chol group, the mean intima/media (I/M) of the internal pudendal artery, which contributes approximately 70% of the total resistance of the penile vasculature, was markedly increased by the treatment (1.82+/-0.25 vs 0.77+/-0.13, P<0.05). Correspondingly, significantly diminished erectile function was observed. Combined treatment for 2 weeks elicited early atherosclerotic changes in proximal arteries and erectile impairment and further 4 weeks of cholesterol diet spread overt atherosclerosis to the periphery. The Chol group showed no arterial pathology, although they showed mild VED. A correlation study showed that atherosclerosis of the distal artery was better correlated with erectile dysfunction than the proximal artery. Based on these results, our study demonstrates that combination treatment of cholesterol diet with L-NAME would be used as a rapid, effective protocol of developing atherosclerotic rat model of VED.

Pion, kaon, and proton production in central Pb-Pb collisions at sqrt[s(NN)] = 2.76 TeV

In this Letter we report the first results on π(±), K(±), p, and p production at midrapidity (|y|<0.5) in central Pb-Pb collisions at sqrt[s(NN)] = 2.76 TeV, measured by the ALICE experiment at the LHC. The p(T) distributions and yields are compared to previous results at sqrt[s(NN)] = 200 GeV and expectations from hydrodynamic and thermal models. The spectral shapes indicate a strong increase of the radial flow velocity with sqrt[s(NN)], which in hydrodynamic models is expected as a consequence of the increasing particle density. While the K/π ratio is in line with predictions from the thermal model, the p/π ratio is found to be lower by a factor of about 1.5. This deviation from thermal model expectations is still to be understood.

Measurement of inelastic, single- and double-diffraction cross sections in proton-proton collisions at the LHC with ALICE

Measurements of cross sections of inelastic and diffractive processes in proton-proton collisions at LHC energies were carried out with the ALICE detector. The fractions of diffractive processes in inelastic collisions were determined from a study of gaps in charged particle pseudorapidity distributions: for single diffraction (diffractive mass MX <200 GeV/c2) [Formula: see text], and [Formula: see text], respectively at centre-of-mass energies [Formula: see text]; for double diffraction (for a pseudorapidity gap Δη>3) σDD/σINEL=0.11±0.03,0.12±0.05, and [Formula: see text], respectively at [Formula: see text]. To measure the inelastic cross section, beam properties were determined with van der Meer scans, and, using a simulation of diffraction adjusted to data, the following values were obtained: [Formula: see text] mb at [Formula: see text] and [Formula: see text] at [Formula: see text]. The single- and double-diffractive cross sections were calculated combining relative rates of diffraction with inelastic cross sections. The results are compared to previous measurements at proton-antiproton and proton-proton colliders at lower energies, to measurements by other experiments at the LHC, and to theoretical models.

National-wide data on the treatment of BPH in Korea

The healthcare system in Korea provides coverage to all the people who are residing in Korea, so the data of the Korea healthcare system are national-wide and relatively accurate. We obtained the recent 5-year data (2004-2008) on the treatment of BPH from the national health insurance system. We tried to determine the trends or changes of BPH treatments in Korea. Over 3.8 million men visited clinics and were prescribed one or more BPH medications, and more than 44 000 men underwent surgical treatment during 2004-2008. Compared with the year 2004, two times the patients were prescribed BPH medications in 2008. With respect to the surgical treatment, the number of cases was increased 1.6 times in 2006 compared with the previous years. The most commonly used surgical option was TURP before 2006, but laser therapy was carried out as much as TURP in 2006 and in the following years. The relative risk of laser therapy in the 50 s is 1.53 (95% CI is 1.47-1.59). In conclusion, our national-wide data for the Korean BPH patients show that these patients' medical treatment increased during the 5 years from 2004 to 2008. Laser treatment had increased and it might replace TURP in several years.