738 research outputs found
Midazolam inhibits hippocampal long-term potentiation and learning through dual central and peripheral benzodiazepine receptor activation and neurosteroidogenesis
Benzodiazepines (BDZs) enhance GABA(A) receptor inhibition by direct actions on central BDZ receptors (CBRs). Although some BDZs also bind mitochondrial receptors [translocator protein (18 kDa) (TSPO)] and promote the synthesis of GABA-enhancing neurosteroids, the role of neurosteroids in the clinical effects of BDZs is unknown. In rat hippocampal slices, we compared midazolam, an anesthetic BDZ, with clonazepam, an anticonvulsant/anxiolytic BDZ that activates CBRs selectively. Midazolam, but not clonazepam, increased neurosteroid levels in CA1 pyramidal neurons without changing TSPO immunostaining. Midazolam, but not clonazepam, also augmented a form of spike inhibition after stimulation adjacent to the pyramidal cell layer and inhibited induction of long-term potentiation. These effects were prevented by finasteride, an inhibitor of neurosteroid synthesis, or 17PA [17-phenyl-(3α,5α)-androst-16-en-3-ol], a blocker of neurosteroid effects on GABA(A) receptors. Moreover, the synaptic effects were mimicked by a combination of clonazepam with FGIN (2-[2-(4-fluorophenyl)-1H-indol-3-yl]-N,N-dihexylacetamide), a selective TSPO agonist, or a combination of clonazepam with exogenous allopregnanolone. Consistent with these in vitro results, finasteride abolished the effects of midazolam on contextual fear learning when administrated 1 d before midazolam injection. Thus, dual activation of CBRs and TSPO appears to result in unique actions of clinically important BDZs. Furthermore, endogenous neurosteroids are shown to be important regulators of pyramidal neuron function and synaptic plasticity
Infrared generation in low-dimensional semiconductor heterostructures via quantum coherence
A new scheme for infrared generation without population inversion between
subbands in quantum-well and quantum-dot lasers is presented and documented by
detailed calculations. The scheme is based on the simultaneous generation at
three frequencies: optical lasing at the two interband transitions which take
place simultaneously, in the same active region, and serve as the coherent
drive for the IR field. This mechanism for frequency down-conversion does not
rely upon any ad hoc assumptions of long-lived coherences in the semiconductor
active medium. And it should work efficiently at room temperature with
injection current pumping. For optimized waveguide and cavity parameters, the
intrinsic efficiency of the down-conversion process can reach the limiting
quantum value corresponding to one infrared photon per one optical photon. Due
to the parametric nature of IR generation, the proposed inversionless scheme is
especially promising for long-wavelength (far- infrared) operation.Comment: 4 pages, 1 Postscript figure, Revtex style. Replacement corrects a
printing error in the authors fiel
Relations Between Molecular Cloud Structure Sizes and Line Widths in the Large Magellanic Cloud
We present a comparative study of the size-line width relation for
substructures within six molecular clouds in the Large Magellanic Cloud (LMC)
mapped with the Atacama Large Millimeter/submillimeter Array (ALMA). Our sample
extends our previous study, which compared a Planck detected cold cloud in the
outskirts of the LMC with the 30 Doradus molecular cloud and found the typical
line width for 1 pc radius structures to be 5 times larger in 30 Doradus. By
observing clouds with intermediate levels of star formation activity, we find
evidence that line width at a given size increases with increasing local and
cloud-scale 8m intensity. At the same time, line width at a given size
appears to independently correlate with measures of mass surface density. Our
results suggest that both virial-like motions due to gravity and local energy
injection by star formation feedback play important roles in determining
intracloud dynamics.Comment: 20 pages, to appear in ApJ. Data presented in this paper can be found
at https://mmwave.astro.illinois.edu/almalmc
Identifying chemokines as therapeutic targets in renal disease: Lessons from antagonist studies and knockout mice
Chemokines, in concert with cytokines and adhesion molecules, play multiple roles in local and systemic immune responses. In the kidney, the temporal and spatial expression of chemokines correlates with local renal damage and accumulation of chemokine receptor-bearing leukocytes. Chemokines play important roles in leukocyte trafficking and blocking chemokines can effectively reduce renal leukocyte recruitment and subsequent renal damage. However, recent data indicate that blocking chemokine or chemokine receptor activity in renal disease may also exacerbate renal inflammation under certain conditions. An increasing amount of data indicates additional roles of chemokines in the regulation of innate and adaptive immune responses, which may adversively affect the outcome of interventional studies. This review summarizes available in vivo studies on the blockade of chemokines and chemokine receptors in kidney diseases, with a special focus on the therapeutic potential of anti-chemokine strategies, including potential side effects, in renal disease. Copyright (C) 2004 S. Karger AG, Basel
Avaliação sócio-ambiental da integração tecnológica Embrapa Pecuåria Sudeste para produção leiteira na agricultura familiar.
Duas caracterĂsticas da pecuĂĄria leiteira podem ser destacadas na atualidade: a) o baixo valor do leite, que dificulta a adoção de tecnologias que favoreçam a produtividade e b) a concentração da produção leiteira em estabelecimentos pequenos, nos quais predomina a atividade em nĂvel de subsistĂȘncia, com mĂŁo-de-obra familiar e renda mensal que nĂŁo ultrapassa um salĂĄrio mĂnimo. Um projeto de pesquisa e transferĂȘncia de tecnologia da Embrapa PecuĂĄria Sudeste (SĂŁo Carlos, Estado de SĂŁo Paulo) vem sendo desenvolvido desde 1998 para melhoria desse cenĂĄrio. Uma vez implantado o projeto em uma sĂ©rie de estabelecimentos na regiĂŁo de Votuporanga, Estado de SĂŁo Paulo, desenvolveu-se este estudo, para avaliar os impactos sĂłcio-ambientais da adoção da tecnologia. Os resultados indicam que o desempenho dos estabelecimentos melhora em função do tempo desde a adoção e que a tecnologia contribui positivamente para o desenvolvimento sustentĂĄvel, sendo recomendada para transferĂȘncia
Structure near ++ threshold in the in-flight He reaction
To search for an S= -1 di-baryonic state which decays to , the reaction was studied at 1.0 GeV/.
Unobserved neutrons were kinematically identified from the missing mass
of the reaction in order to have a large
acceptance for the final state. The observed events,
distributed widely over the kinematically allowed region of the Dalitz plot,
establish that the major component comes from a three nucleon absorption
process. A concentration of events at a specific neutron kinetic energy was
observed in a region of low momentum transfer to the . To account
for the observed peak structure, the simplest S-wave pole was assumed to exist
in the reaction channel, having Breit-Wigner form in energy and with a Gaussian
form-factor. A minimum method was applied to deduce its mass
2355 (stat.) (syst.) MeV/c, and decay-width
110 (stat.) (syst.) MeV/c,
respectively. The form factor parameter 400 MeV/ implies that the
range of interaction is about 0.5Comment: 12pages, 8 figure
Measurement of the strong interaction induced shift and width of the 1s state of kaonic deuterium at J-PARC
The antikaon-nucleon interaction close to threshold provides crucial
information on the interplay between spontaneous and explicit chiral symmetry
breaking in low-energy QCD. In this context the importance of kaonic deuterium
X-ray spectroscopy has been well recognized, but no experimental results have
yet been obtained due to the difficulty of the measurement. We propose to
measure the shift and width of the kaonic deuterium 1s state with an accuracy
of 60 eV and 140 eV respectively at J-PARC. These results together with the
kaonic hydrogen data (KpX at KEK, DEAR and SIDDHARTA at DAFNE) will then permit
the determination of values of both the isospin I=0 and I=1 antikaon-nucleon
scattering lengths and will provide the most stringent constraints on the
antikaon-nucleon interaction, promising a breakthrough. Refined Monte Carlo
studies were performed, including the investigation of background suppression
factors for the described setup. These studies have demonstrated the
feasibility of determining the shift and width of the kaonic deuterium atom 1s
state with the desired accuracy of 60 eV and 140 eV.Comment: 12 pages, 9 figure
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