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1.
Background
Taste receptor cells are responsible for transducing chemical stimuli into electrical signals that lead to the sense of taste. An important second messenger in taste transduction is IP3, which is involved in both bitter and sweet transduction pathways. Several components of the bitter transduction pathway have been identified, including the T2R/TRB taste receptors, phospholipase C β2, and the G protein subunits α-gustducin, β3, and γ13. However, the identity of the IP3 receptor subtype in this pathway is not known. In the present study we used immunocytochemistry on rodent taste tissue to identify the IP3 receptors expressed in taste cells and to examine taste bud expression patterns for IP3R3. 相似文献2.
Background
Previous studies have demonstrated that neonatal manipulation of oxytocin (OT) has effects on the expression of estrogen receptor α (ERα) and the central production of oxytocin observed in juveniles (at weaning, 21 days of age). The goal of this study was to determine whether the effects of neonatal manipulation of OT last into adulthood, and if the effects differ from those observed during the early postnatal period. On the first day of life, prairie voles (Microtus ochrogaster) received one of three doses of OT (High, 3 μg; Med, 0.3 μg; Low, 0.03 μg), an OT antagonist, or isotonic saline. Another group was handled, but not injected. Then as adults, brains were collected, sectioned, and stained for ERα or OT using immunocytochemistry. 相似文献3.
Marco Tizzano Gennady Dvoryanchikov Jennell K Barrows Soochong Kim Nirupa Chaudhari Thomas E Finger 《BMC neuroscience》2008,9(1):110
Background
"Type II"/Receptor cells express G protein-coupled receptors (GPCRs) for sweet, umami (T1Rs and mGluRs) or bitter (T2Rs), as well as the proteins for downstream signalling cascades. Transduction downstream of T1Rs and T2Rs relies on G-protein and PLCβ2-mediated release of stored Ca2+. Whereas Gαgus (gustducin) couples to the T2R (bitter) receptors, which Gα-subunit couples to the sweet (T1R2 + T1R3) receptor is presently not known. We utilized RT-PCR, immunocytochemistry and single-cell gene expression profiling to examine the expression of the Gαq family (q, 11, 14) in mouse taste buds. 相似文献4.
A variational approach is developed for bound state calculations in three- and four-electron atomic systems. This approach
can be applied to determine, in principle, an arbitrary bound state in three- and four-electron ions and atoms. Our variational
wave functions are constructed from four- and five-body Gaussoids that respectively depend on six (r
12, r
13, r
14, r
23, r
24, r
34) and ten (r
12, r
13, r
14, r
15, r
23, r
24, r
25, r
34, r
35 and r
45) relative coordinates. The approach allows operating with the more than one electron spin functions. In particular, the trial
wave functions for the 1
S states in four-electron atomic systems include the two independent spin functions χ1 = αβαβ + βαβα − βααβ − αββα and χ2 = 2ααββ + 2ββαα − βααβ − αββα − βαβα − αβαβ. We also discuss the construction of variational wave functions for the excited
23
S states in four- electron atomic systems. 相似文献
5.
We define a class of weakly self-avoiding walks on the integers by conditioning a simple random walk of length n to have a p-fold self-intersection local time smaller than n
β
, where 1<β<(p+1)/2. We show that the conditioned paths grow of order n
α
, where α=(p−β)/(p−1), and also prove a coarse large deviation principle for the order of growth. 相似文献
6.
Background
Recent data indicate that excitotoxicity of high levels of neurotransmitter glutamate may be mediated via programmed cell death (apoptosis) and that it can be prevented in HT22 mouse hippocampal cells by various equine estrogens with Δ8,17β-estradiol (Δ8,17β-E2) being the most potent. In order to delineate the mechanism(s), glutamate-induced cell death of HT22 cells was assessed by measuring (a) DNA fragmentation in the presence or absence of 11 equine estrogens (components of the drug CEE); (b) cell death and (c) levels of anti-apoptotic (Bcl-2) and proapoptotic (Bax) proteins in the presence or absence of two equine estrogens, Δ8,17β-E2 and 17β-estradiol (17β-E2) by LDH release assay and Western blot analysis respectively. 相似文献7.
The average spreading and directionality of broadband partially coherent beam (BPCB) in non-Kolmogorov turbulence is studied.
The effects of exponent value α, propagation distance, spectrum width, inner and outer scale parameters is studied in detail. Numerical calculation reveals
that the beam width increases with the increasing in spectrum bandwidth just like when propagating in Kolmogorov turbulence,
however, the beam width may vary as much as by a factor of 50% with different α. The difference in beam width between monochromatic partially coherent beam (MPCB) and BPCB at the receiving plane may vary
from 2% to 10% with different α. The angular spreading is more sensitive to α than the spectrum bandwidth; also it is more sensitive to the inner scale parameters than the outer scale parameter. 相似文献
8.
9.
Marcella Reale Antonia Patruno Maria A De Lutiis Mirko Pesce Mario Felaco Massimo Di Giannantonio Marta Di Nicola Alfredo Grilli 《BMC neuroscience》2011,12(1):13
Background
The exact cause of schizophrenia is not known, although several aetiological theories have been proposed for the disease, including developmental or neurodegenerative processes, neurotransmitter abnormalities, viral infection and immune dysfunction or autoimmune mechanisms. Growing evidence suggests that specific cytokines and chemokines play a role in signalling the brain to produce neurochemical, neuroendocrine, neuroimmune and behavioural changes. A relationship between inflammation and schizophrenia was supported by abnormal cytokines production, abnormal concentrations of cytokines and cytokine receptors in the blood and cerebrospinal fluid in schizophrenia. Since the neuropathology of schizophrenia has recently been reported to be closely associated with microglial activation we aimed to determined whether spontaneous or LPS-induced peripheral blood mononuclear cell chemokines and cytokines production is dysregulated in schizophrenic patients compared to healthy subjects. We enrolled 51 untreated first-episode schizophrenics (SC) and 40 healthy subjects (HC) and the levels of MCP-1, MIP-1α, IL-8, IL-18, IFN-γ and RANTES were determined by Elisa method in cell-free supernatants of PBMC cultures. 相似文献10.
Xuewen Wu Dalian Ding Haiyan Jiang Xiaowei Xing Suping Huang Hong Liu Zhedong Chen Hong Sun 《Journal of nanoparticle research》2012,14(1):708-13
Hydroxyapatite nanoparticles (nHAT) are known to have excellent biocompatibility, and have attracted increasing attention
as new candidates of non-viral vectors for gene therapy. In our previous studies, nHAT carrying a therapeutic gene and a reporter
gene were successfully transfected into the spiral ganglion neurons in the inner ear of guinea pigs in vivo as well as in
the cultured cell lines, although the transfection efficiencies were never higher than 30%. In this study, the surface modification
of nHAT with polyethylenimine (PEI) was made (PEI–nHAT, diameter = 73.09 ± 27.32 nm) and a recombinant plasmid carrying enhanced
green fluorescent protein (EGFP) gene and neurotrophin-3 (NT-3) gene was constructed as pEGFPC2–NT3. The PEI modified nHAT
and the recombinant plasmid was then connected to form the nHAT-based vector–gene complex (PEI–nHAT–pEGFPC2–NT3). This complex
was then placed onto the intact round window membranes of the chinchillas for inner ear transfection. Auditory brainstem response
(ABR) was tested to evaluate auditory function. Green fluorescence of EGFP was observed using confocal microscopy 48 h after
administering vector–gene complexes. There was no significant threshold shift in tone burst-evoked ABR at any tested frequency.
Abundant, condensed green fluorescence was found in dark cells on both sides of the crista and around the macula of the utricle.
Scattered EGFP signals were also detected in vestibular hair cells, some Schwann cells in the cochlear spiral ganglion region,
some outer pillar cells in the organ of Corti, and a few cells in the stria vascularis. The density of green fluorescence-marked
cells was obviously higher in the vestibular dark cell area than in other areas of the inner ear, suggesting that vestibular
dark cells may have the ability to actively engulf the nHAT-based vector–gene complexes. Considering the high transfection
efficiency in the vestibular system, PEI–nHAT may be a potential vector for gene therapy of inner ear diseases, especially
vestibular disorders, and deserves further study. 相似文献
11.
Background
In rodents, dietary Na+ deprivation reduces gustatory responses of primary taste fibers and central taste neurons to lingual Na+ stimulation. However, in the rat taste bud cells Na+ deprivation increases the number of amiloride sensitive epithelial Na+ channels (ENaC), which are considered as the "receptor" of the Na+ component of salt taste. To explore the mechanisms, the expression of the three ENaC subunits (α, β and γ) in taste buds were observed from rats fed with diets containing either 0.03% (Na+ deprivation) or 1% (control) NaCl for 15 days, by using in situ hybridization and real-time quantitative RT-PCR (qRT-PCR). Since BDNF/TrkB signaling is involved in the neural innervation of taste buds, the effects of Na+ deprivation on BDNF and its receptor TrkB expression in the rat taste buds were also examined. 相似文献12.
Serdar Durdagi Manthos G. Papadopoulos Panagiotis G. Zoumpoulakis Catherine Koukoulitsa Thomas Mavromoustakos 《Molecular diversity》2010,14(2):257-276
When X-ray structure of a ligand-bound receptor is not available, homology models of the protein of interest can be used to
obtain the ligand-binding cavities. The steroelectronic properties of these cavities are directly related to the performed
molecular model coordinates. Thus, the use of different template structures for homology may result in variation of ligand-binding
modes. We have recently reported the MD simulations of a potent CB ligand at bovine rhodopsin-based CB1 and CB2 receptors
(Durdagi et al., Bioorg Med Chem 16:7377–7387, 2008). In this present study, a homology modeling study based on the β2-adrenergic receptor for both CB1 and CB2 receptors was performed, and the results were compared with rhodopsin-based models.
In addition, the role of membrane bilayers to the adopted conformations of potent AMG3 CB ligand has been analyzed for receptor-free
and membrane-associated receptor systems. The performed MD trajectory analysis results have shown that gauche conformations at the terminal segment of the alkyl side chain of AMG3 are not favored in solution. Different adopting dihedral
angles defined between aromatic and dithiolane rings at the active sites of the CB1 and CB2 receptors, which are adapted lead
to different alkyl side chain orientations and thus, may give clues to the medicinal chemists to synthesize more selective
CB ligands. The binding sites of receptors derived by rhodopsin-based models have been regenerated using the β2-adrenergic based template receptors. The re-obtained models confirmed the ligand-binding pockets that were derived based
on rhodopsin. 相似文献
13.
L. G. Moyano A. P. Majtey C. Tsallis 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,52(4):493-500
We introduce, and numerically study, a system of N symplectically and globally coupled
standard maps localized in a d=1 lattice array. The global coupling is modulated
through a factor r-α, being
r the distance between maps. Thus, interactions are long-range (nonintegrable) when
0≤α≤1, and short-range (integrable) when α>1.
We verify that the largest Lyapunov exponent λM scales as λM ∝
N-κ(α), where κ(α) is positive when interactions are
long-range, yielding weak chaos in the thermodynamic
limit N↦∞ (hence λM→0). In the short-range case,
κ(α) appears to vanish,
and the behaviour corresponds to strong chaos. We show that, for certain
values of the control parameters of the system, long-lasting metastable states
can be present. Their duration tc scales as tc ∝Nβ(α),
where β(α) appears to be numerically in agreement with the following
behavior: β>0 for 0 ≤α< 1, and zero for α≥1.
These results are consistent with features typically found in nonextensive statistical mechanics.
Moreover, they exhibit strong similarity between the present
discrete-time system, and the α-XY Hamiltonian ferromagnetic model. 相似文献
14.
M. Loulidi 《Journal of statistical physics》2008,132(1):109-127
A one-dimensional disordered particle hopping rate asymmetric exclusion process (ASEP) with open boundaries and a random sequential
dynamics is studied analytically. Combining the exact results of the steady states in the pure case with a perturbative mean
field-like approach the broken particle-hole symmetry is highlighted and the phase diagram is studied in the parameter space
(α,β), where α and β represent respectively the injection rate and the extraction rate of particles. The model displays, as in the pure case,
high-density, low-density and maximum-current phases. All critical lines are determined analytically showing that the high-density
low-density first order phase transition occurs at α≠β. We show that the maximum-current phase extends its stability region as the disorder is increased and the usual
-decay of the density profile in this phase is universal. Assuming that some exact results for the disordered model on a ring
hold for a system with open boundaries, we derive some analytical results for platoon phase transition within the low-density
phase and we give an analytical expression of its corresponding critical injection rate α
*. As it was observed numerically (Bengrine et al. J. Phys. A: Math. Gen. 32:2527, [1999]), we show that the quenched disorder induces a cusp in the current-density relation at maximum flow in a certain region
of parameter space and determine the analytical expression of its slope. The results of numerical simulations we develop agree
with the analytical ones.
Regular associate of ICTP. 相似文献
15.
Background
Stargazin (γ2) and the closely related γ3, and γ4 transmembrane proteins are part of a family of proteins that may act as both neuronal voltage-dependent calcium channel (VDCC) γ subunits and transmembrane α-amino-3-hydroxy-5-methyl-4-isoxazoleproponinc (AMPA) receptor regulatory proteins (TARPs). In this investigation, we examined the distribution patterns of the stargazin-like proteins γ2, γ3, and γ4 in the human central nervous system (CNS). In addition, we investigated whether human γ2 or γ4 could modulate the electrophysiological properties of a neuronal VDCC complex transiently expressed in Xenopus oocytes. 相似文献16.
The focal switch of cosine-Gaussian (CsG) beams passing through a system with the aperture and lens separated is studied analytically
and numerically. It is shown that the focal switch of CsG beams can appear not only for the apertured case, but also for the
unapertured case. The necessary condition for the focal switch is that truncation parameter α > αc and the beam parameter β > βc, αc, βc being the corresponding critical values. There exists a maximum of the relative transition height Δz
sw as α varies, and Δz
sw increases with increasing β and decreasing N
w. The normalized axial intensity minimum I
min / I
max decreases with an increase of α and β, and I
min / I
max remains unchanged as N
w varies. 相似文献
17.
Gérard Ben Arous Anton Bovier Jiří Černý 《Communications in Mathematical Physics》2008,282(3):663-695
We consider a version of Glauber dynamics for a p-spin Sherrington– Kirkpatrick model of a spin glass that can be seen as a time change of simple random walk on the N-dimensional hypercube. We show that, for all p ≥ 3 and all inverse temperatures β > 0, there exists a constant γ
β ,p
> 0, such that for all exponential time scales, exp(γ N), with γ < γ
β ,p
, the properly rescaled clock process (time-change process) converges to an α-stable subordinator where α = γ/β
2 < 1. Moreover, the dynamics exhibits aging at these time scales with a time-time correlation function converging to the arcsine
law of this α-stable subordinator. In other words, up to rescaling, on these time scales (that are shorter than the equilibration time
of the system) the dynamics of p-spin models ages in the same way as the REM, and by extension Bouchaud’s REM-like trap model, confirming the latter as a
universal aging mechanism for a wide range of systems. The SK model (the case p = 2) seems to belong to a different universality class. 相似文献
18.
The flip-annihilation process is a random particle process with one-dimensional local interaction in discrete time, initially
presented by one of us, namely Toom in 2004. Its components are enumerated by integer numbers and every component has two
states, “minus” and “plus”. At every time step two transformations occur. The first one, called “flip”, independently turns
every minus into plus with probability β. The second one, called “annihilation”, acts thus: whenever a plus is a left neighbor of a minus, both disappear with probability
α independently from other components. What is interesting about this process is that it is ergodic for β>α/2 and non-ergodic for β<α
2/250. It is natural to conjecture that there is some transition curve, which we call the true curve and denote by
, which separates the areas of ergodicity and non-ergodicity of this process from each other. The estimates, mentioned above,
albeit rigorous, leave a large gap between them and the present article’s purpose is to obtain some closer, albeit non-rigorous,
approximations of the true curve. We do it in two ways, one of which is a chaos approximation and the other is a Monte Carlo
simulation. Thus we obtain two curves, which are much closer to each other than the rigorous estimations. Also we fill in,
albeit only numerically, another shortcoming of the rigorous estimation β<α
2/250, namely that it leaves us uncertain whether the true curve has a zero or positive slope at the point α=β=0. Both approximate curves have a positive slope at α=0, as we hoped. 相似文献
19.
I.M. Sokolov 《The European Physical Journal B - Condensed Matter and Complex Systems》2001,22(3):369-373
We consider two-particle dispersion in a velocity field, where the relative two-point velocity scales according to v
2(r) ∝r
α and the corresponding correlation time scales as τ(r) ∝r
β, and fix α = 2/3, as typical for turbulent flows. We show that two generic types of dispersion behavior arize: For α/2 +
β < 1 the correlations in relative velocities decouple and the diffusion approximation holds. In the opposite case, α/2 +
β > 1, the relative motion is strongly correlated. The case of Kolmogorov flows corresponds to a marginal, nongeneric situation.
In this case, depending on the particular parameters of the flow, the dispersion behavior can be rather diffusive or rather
ballistic.
Received 13 March 2001 相似文献
20.
Blinking of single molecules and nanocrystals is modeled as a two-state renewal process with on (fluorescent) and off (non-fluorescent)
states. The on and off-times may have power-law or exponential distributions. A fractional generalization of the exponential
function is used to develop a unified treatment of the blinking statistics for both types of distributions. In the framework
of the two-state model, an equation for the probability density p(t
on|t) of the total on-time is derived. As applied to power-law blinking, the equation contains derivatives of fractional orders
α and β equal to the exponents of the on and off-time power-law distributions, respectively. In the limit case of α = β =
1, the distributions become exponential and the fractional differential equation reduces to an integer order differential
equation. Solutions to these equations are expressed in terms of fractional stable distributions. The Poisson transform of
p(t
on|t) is the photon number distribution that determines the photon counting statistics. It is shown that the long-time asymptotic
behavior of Mandel’s Q parameter follows a power law: M(t) ∝ t
γ
. The function γ(α, β) is defined on the (α, β) plane. An analysis of the relative variance of the total on-time shows that it decays only
when α = β = 1 or α < β. Otherwise, relative fluctuations either exhibit asymptotic power-law growth or approach a constant
level. Analytical calculations are in good agreement with the results of Monte Carlo simulations. 相似文献