799 research outputs found
Building C(sp(3)) Molecular Complexity on 2,2 '-Bipyridine and 1,10-Phenanthroline in Rhenium Tricarbonyl Complexes
The reactions of [Re(N-N)(CO)(3)(PMe3)]OTf (N-N=2,2 '-bipyridine, bipy; 1,10-phenanthroline, phen) compounds with tBuLi and with LiHBEt3 have been explored. Addition to the N-N chelate took place with different site-selectivity depending on both chelate and nucleophile. Thus, with tBuLi, an unprecedented addition to C5 of bipy, a regiochemistry not accessible for free bipy, was obtained, whereas coordinated phen underwent tBuLi addition to C2 and C4. Remarkably, when LiHBEt3 reacted with [Re(bipy)(CO)(3)(PMe3)]OTf, hydride addition to the 4 and 6 positions of bipy triggered an intermolecular cyclodimerization of two dearomatized pyridyl rings. In contrast, hydride addition to the phen analog resulted in partial reduction of one pyridine ring. The resulting neutral Re-I products showed a varied reactivity with HOTf and with MeOTf to yield cationic complexes. These strategies rendered access to Re-I complexes containing bipy- and phen-derived chelates with several C(sp(3)) centers
Sawtooth waves during REM sleep after administration of haloperidol combined with total sleep deprivation in healthy young subjects
We sought to examine the possible participation of dopaminergic receptors in the phasic events that occur during rapid eye movement (REM) sleep, known as sawtooth waves (STW). These phasic phenomena of REM sleep exhibit a unique morphology and, although they represent a characteristic feature of REM sleep, little is known about the mechanisms which generate them and which are apparently different from rapid eye movements. STW behavior was studied in 10 male volunteers aged 20 to 35 years, who were submitted to polysomnographic monitoring (PSG). On the adaptation night they were submitted to the first PSG and on the second night, to the basal PSG. On the third night the volunteers received placebo or haloperidol and spent the whole night awake. On the fourth night they were submitted to the third PSG. After a 15-day rest period, the volunteers returned to the sleep laboratory and, according to a double-blind crossover randomized design, received haloperidol or placebo and spent the whole night awake, after which they were submitted to the fourth PSG. The volunteers who were given haloperidol combined with sleep deprivation exhibited an elevation of the duration and density of the STW, without significant alterations of the other REM sleep phasic phenomena such as rapid eye movement. These findings suggest that sawtooth waves must have their own generating mechanisms and that the dopaminergic receptors must exert a modulating role since REM sleep deprivation, as well as administration of neuroleptics, produces supersensitivity of dopaminergic receptors.Universidade Federal de São Paulo (UNIFESP) Escola Paulista de Medicina Departamento de PsicobiologiaUNIFESP, EPM, Depto. de PsicobiologiaSciEL
Is atherosclerosis an autoimmune disease?
Immunologic research into pathogenic mechanisms operating in autoimmune-mediated atherosclerosis initially focused on adaptive immunity. Current interest is directed to more basic inflammatory mechanisms. Chronic inflammation (innate immunity-associated) may trigger initial events that can lead to atherosclerotic cardiovascular disease. This chronic inflammation may start early in life and be perpetuated by classic atherosclerosis risk factors. Lipid peroxidation of low-density lipoprotein seems to be a key event in the initiation and progression of atherosclerosis. Oxidized low-density lipoprotein triggers inflammatory and immunogenic events that promote endothelial dysfunction and the synthesis and secretion of pro-inflammatory cytokines, leading to an autoimmune response capable of accelerating the intracellular accumulation of lipids within atherosclerotic plaques. Oxidized low-density lipoprotein binds \u3b22-glycoprotein I to form circulating complexes found in both autoimmune and non-autoimmune atherosclerosis. It is likely that \u3b22-glycoprotein I and/or these complexes contribute to early atherogenesis by stimulating pro-inflammatory innate immunity through endogenous sensors and inflammasome/interleukin-1 pathways. We discuss the chronic inflammatory (innate) and autoimmune (adaptive) responses operating in atherosclerosis to discern the role of autoimmunity in atherosclerotic cardiovascular disease
The Volume of the Past Light-Cone and the Paneitz Operator
We study a conjecture involving the invariant volume of the past light-cone
from an arbitrary observation point back to a fixed initial value surface. The
conjecture is that a 4th order differential operator which occurs in the theory
of conformal anomalies gives when acted upon the invariant volume of the
past light-cone. We show that an extended version of the conjecture is valid
for an arbitrary homogeneous and isotropic geometry. First order perturbation
theory about flat spacetime reveals a violation of the conjecture which,
however, vanishes for any vacuum solution of the Einstein equation. These
results may be significant for constructing quantum gravitational observables,
for quantifying the back-reaction on spacetime expansion and for alternate
gravity models which feature a timelike vector field.Comment: 22 pages, no figures, 5 tables. Version 2 substantially extended to
cover nonzero spatial curvature, and with simplified derivation
in interacting quintessence model
A model consisting of quintessence scalar field interacting with cold dark
matter is considered. Conditions required to reach are discussed. It
is shown that depending on the potential considered for the quintessence,
reaching the phantom divide line puts some constraints on the interaction
between dark energy and dark matter. This also may determine the ratio of dark
matter to dark energy density at .Comment: 10 pages, references updated, some notes added, minor changes
applied, accepted for publication in Eur. Phys. J.
Generation of a gene-corrected human isogenic line (UAMi006-A) from propionic acidemia patient iPSC with an homozygous mutation in the PCCB gene using CRISPR/Cas9 technology
Propionic acidemia (PA) is an inherited metabolic disease caused by mutations in the PCCA and PCCB genes. We have previously generated an induced pluripotent stem cell (iPSC) line (UAMi004-A) from a PA patient with the c.1218_1231del14ins12 (p.Gly407Argfs*14) homozygous mutation in the PCCB gene. Here, we report the generation of the isogenic control in which the mutation was genetically corrected using CRISPR/Cas9 technology. Off-target editing presence was excluded and the iPSCs had typical embryonic stem cell-like morphology and normal karyotype that expressed pluripotency markers and maintained their in vitro differentiation potential.Functional Genomics of Muscle, Nerve and Brain Disorder
Homogenization and seismic assessment : review and recent trends
The mechanics of masonry structures has been for long
underdeveloped in comparison with other fields of knowledge. Presently,
non-linear analysis is a popular field in masonry research and
advanced computer codes are available for researchers and practitioners.
The chapter presents a discussion of masonry behaviour and
clarifies how to obtain the non-linear data required by the computations.
The chapter also addresses different homogenisation techniques
available in the literature in the linear and rigid-plastic case,
aiming at defining a catalogue and at discussing the advantages and
disadvantages of the different approaches. Special attention is given
to stress assumed models based either on a polynomial expansion
of the micro-stress field or in the discretization of the unit cell by
means of a few constant stress finite elements CST with joints reduced
to interfaces. Finally, the aspects of seismic assessment are
presented and case studies involving the use of macro-block analysis,
static (pushover) analysis and time integration analysis are
discussed.(undefined
Adsorption of mono- and multivalent cat- and anions on DNA molecules
Adsorption of monovalent and multivalent cat- and anions on a deoxyribose
nucleic acid (DNA) molecule from a salt solution is investigated by computer
simulation. The ions are modelled as charged hard spheres, the DNA molecule as
a point charge pattern following the double-helical phosphate strands. The
geometrical shape of the DNA molecules is modelled on different levels ranging
from a simple cylindrical shape to structured models which include the major
and minor grooves between the phosphate strands. The densities of the ions
adsorbed on the phosphate strands, in the major and in the minor grooves are
calculated. First, we find that the adsorption pattern on the DNA surface
depends strongly on its geometrical shape: counterions adsorb preferentially
along the phosphate strands for a cylindrical model shape, but in the minor
groove for a geometrically structured model. Second, we find that an addition
of monovalent salt ions results in an increase of the charge density in the
minor groove while the total charge density of ions adsorbed in the major
groove stays unchanged. The adsorbed ion densities are highly structured along
the minor groove while they are almost smeared along the major groove.
Furthermore, for a fixed amount of added salt, the major groove cationic charge
is independent on the counterion valency. For increasing salt concentration the
major groove is neutralized while the total charge adsorbed in the minor groove
is constant. DNA overcharging is detected for multivalent salt. Simulations for
a larger ion radii, which mimic the effect of the ion hydration, indicate an
increased adsorbtion of cations in the major groove.Comment: 34 pages with 14 figure
Low Q^2 Jet Production at HERA and Virtual Photon Structure
The transition between photoproduction and deep-inelastic scattering is
investigated in jet production at the HERA ep collider, using data collected by
the H1 experiment. Measurements of the differential inclusive jet
cross-sections dsigep/dEt* and dsigmep/deta*, where Et* and eta* are the
transverse energy and the pseudorapidity of the jets in the virtual
photon-proton centre of mass frame, are presented for 0 < Q2 < 49 GeV2 and 0.3
< y < 0.6. The interpretation of the results in terms of the structure of the
virtual photon is discussed. The data are best described by QCD calculations
which include a partonic structure of the virtual photon that evolves with Q2.Comment: 20 pages, 5 Figure
Energy Flow in the Hadronic Final State of Diffractive and Non-Diffractive Deep-Inelastic Scattering at HERA
An investigation of the hadronic final state in diffractive and
non--diffractive deep--inelastic electron--proton scattering at HERA is
presented, where diffractive data are selected experimentally by demanding a
large gap in pseudo --rapidity around the proton remnant direction. The
transverse energy flow in the hadronic final state is evaluated using a set of
estimators which quantify topological properties. Using available Monte Carlo
QCD calculations, it is demonstrated that the final state in diffractive DIS
exhibits the features expected if the interaction is interpreted as the
scattering of an electron off a current quark with associated effects of
perturbative QCD. A model in which deep--inelastic diffraction is taken to be
the exchange of a pomeron with partonic structure is found to reproduce the
measurements well. Models for deep--inelastic scattering, in which a
sizeable diffractive contribution is present because of non--perturbative
effects in the production of the hadronic final state, reproduce the general
tendencies of the data but in all give a worse description.Comment: 22 pages, latex, 6 Figures appended as uuencoded fil
- …