Immunodetection and enzymatic characterization of the α3-isoform of Na,K-ATPase in dog heart

AbstractThe expression of the canine α 2 and 3 subunit isoenzymes of NA,K-ATPase has been investigated in plasma membranes isolated from dog heart, brain and kidney by immunoblotting, employing polyclonal anti rat fusion protein, and enzymological techniques. Western blot analysis revealed with purified dog membrane Na,K-ATPase preparations, one immunoreactive signal with rat specific α3 antisera in cardiac tissues, and two immunoreactive signals with rat α3 and α3 antisera in cerebral tissues. These findings suggested the specific expression of α3 polypeptide in dog heart (99 kDa), whereas dog brain expressed the α 2 and 3 polypeptides. The stained bands were superimposed. The antibody to rat brain α1 fusion protein did not cross-react with dog antigens whatever the three tissues tested. Expression of the α3-subunit isoform in dog heart membranes was consistent with a high affinity digitoxigenin-sensitive class of Na,K-ATPase (IC50 = 7 ± 2 nM). A single component with low affinity to digitoxigenin (IC50 = 110 ± 10 nM) characterized the α1 kidney form. The mixture of α2 and α3 isoforms in dog brain exhibited an apparent affinity for digitoxigenin (IC50 = 17 ± 5 nM) lower than the heart. The sodium dependences of the high affinity digitoxigenin sites were for the cardiac α3 form (K0.5 = 10 ± 1.9 mM) and for the cerebral α2 and α3 mixture (K5.0 19.6 ± 4.9 mM). The sensitivities for Na+ of the low affinity sites (α1) were: 6.7 ± 1.4 mM, 6.3 ± 1.2 mM and 11.6 ± 2.9 mM in heart, brain and kidney respectively. This is the first report of the catalytic characteristics of the α3 subunit isoenzyme in canine cardiac plasma membranes

Ondes scélérates et autres manifestations extrêmes dans les fibres optiques

National audienceNous présentons divers exemples d'évènements rares optiques qui peuvent apparaître lors de la propagation d'impulsions dans des fibres optiques. Ainsi, différents types de structures optiques se démarquant très nettement du comportement statistique moyen ont été mis en évidence dans les processus de génération de supercontinua optiques ainsi que dans les phases d'amplification paramétrique ou Raman

Structural Change in Industrial Output: China 1995-2010.

Purpose The aim of this paper is to learn about some patterns of sectoral and industrial structural change of the Chinese economy over the 1995-2010 period, which also complements a previous paper of the author. The chosen period is about (and conveniently) bounded by two international crises: the Southeast Asian crisis of 1997 and the world crisis that started in 2007/2008. Design/methodology/approach To such a purpose, this paper set up a quantitative methodology via input-output modelling, which allows us to decompose gross output into some key demand sources or contributions. These are then analyzed over the full period. Findings It can be shown that the trajectory of the main structural patterns over the period was not smooth and was pretty unbalanced and that they generally responded to both domestic policy and international shocks. Export demand and heavy industry appeared to be the main engines of the economy, which showed massive increases in their share of output, at the expense of domestic demand, services and agriculture. Despite the high growth rates over this period, the Chinese economy seemed to be in need of rebalancing, which seems to have started toward the end of the authors’ period. Originality/value The decomposition method has been applied before by the author and others, but the variations in this paper are original, just as original is the application to China (never been done before), which in addition is not confined to two or so snapshots separated by many years, as is the usual use, but to the full year-after-year change of the sectoral and industrial structure over this study’s focus period

Coulomb blockade of strongly coupled quantum dots studied via bosonization of a channel with a finite barrier

A pair of quantum dots, coupled through a point contact, can exhibit Coulomb blockade effects that reflect an oscillatory term in the dots' total energy whose value depends on whether the total number of electrons on the dots is even or odd. The effective energy associated with this even-odd alternation is reduced, relative to the bare Coulomb blockade energy for uncoupled dots, by a factor (1-f) that decreases as the interdot coupling is increased. When the transmission coefficient for interdot electronic motion is independent of energy and the same for all channels within the point contact (which are assumed uncoupled), the factor (1-f) takes on a universal value determined solely by the number of channels and the dimensionless conductance g of each individual channel. This paper studies corrections to the universal value of (1-f) that result when the transmission coefficent varies over energy scales of the size of the bare Coulomb blockade energy. We consider a model in which the point contact is described by a single orbital channel containing a parabolic barrier potential, and we calculate the leading correction to (1-f) for one-channel (spin-split) and two-channel (spin-degenerate) point contacts in the limit where the single orbital channel is almost completely open. By generalizing a previously used bosonization technique, we find that, for a given value of the dimensionless conductance g, the value of (1-f) is increased relative to its value for a zero-thickness barrier, but the absolute value of the increase is small in the region where our calculations apply.Comment: 13 pages, 3 Postscript figure

Surface Magnetization of Aperiodic Ising Quantum Chains

We study the surface magnetization of aperiodic Ising quantum chains. Using fermion techniques, exact results are obtained in the critical region for quasiperiodic sequences generated through an irrational number as well as for the automatic binary Thue-Morse sequence and its generalizations modulo p. The surface magnetization exponent keeps its Ising value, beta_s=1/2, for all the sequences studied. The critical amplitude of the surface magnetization depends on the strength of the modulation and also on the starting point of the chain along the aperiodic sequence.Comment: 11 pages, 6 eps-figures, Plain TeX, eps

Beam dynamics studies in SPIRAL II LINAC

ACCInternational audienceThe proposed LINAG driver for the SPIRAL 2 project aims to accelerate a 5-mA D+ beam up to 20 A.MeV and 1-mA beam for q/A=1/3 up to 14.5 A.MeV. It is acontinuous wave regime (cw), designed for maximum efficiency in the transmission of intense beams. It consists of an injector (two ECR sources + a Radio Frequency Quadrupole) followed by a superconducting section based on an array of independently phased cavities. This paper presents beams dynamics studies associated to the LINAG driver. End-to-end simulations (low-energy beam lines, RFQ, medium-energy beam line, SC linac) are shown

Magnetic field strength and orientation effects on co-fe discontinuous multilayers close to percolation

International audienceMagnetization and magnetoresistance in function of the magnitude and orientation of applied magnetic field were studied in Co-Fe discontinuous multilayers close to their structural percolation. The high pulsed magnetic fields up to 33 T were used in the 120–310 K temperature range. Comparison between longitudinal and transverse with respect to the film plane field configurations was made in the low-field and high-field regimes in order to clarify the nature of the measured negative magnetoresistance. Coexistence of two distinct magnetic fractions, superparamagnetic SPM, consisting of small spherical Co-Fe granules and superferromagnetic SFM, by bigger Co-Fe clusters, was established in this system. These fractions were shown to have different relevance for the system magnetization and magnetotransport. While the magnetization is almost completely up to 97% defined by the SFM contribution and practically independent of temperature in this range, the magnetoresistance experiences a crossover from a regime dominated by Langevin correlations suppressed with temperature between neighbor SPM and SFM moments at low fields, to that dominated by spin scattering enhanced with temperature of charge carriers within SFM clusters at high fields. Also, the demagnetizing effects, sensitive to the field orientation, were found to essentially define the low-field behavior and characteristic crossover field

Percutaneous transluminal coronary rotary ablation with rotablator (European experience)

This study reports the results from 3 European centers using rotary ablation with Rotablator, a device that is inserted into the coronary artery and removes atheroma by grinding it into millions of tiny fragments. Rotary ablation was performed in 129 patients. Primary success (reduction in percent luminal narrowing greater than 20%, residual stenosis less than 50%, without complications) was achieved by rotary angioplasty alone in 73 patients (57%). An additional 38 patients (29%) had successful adjunctive balloon angioplasty. Thus primary success was achieved in 111 patients (86%) at the end of the procedure. Acute occlusion occurred in 10 patients (7.7%). Recanalization was achieved by balloon angioplasty in 7: urgent bypass grafting was undertaken in 2. Q-wave and non-Q-wave myocardial infarction occurred in 3 and 7 patients, respectively. No deaths occurred. Follow-up angiography was performed in 74 patients (60%). Restenosis, defined as the recurrence of significant luminal narrowing (greater than 50%) occurred in 17 of 37 patients (46%) who underwent rotary ablation alone, and 11 of 37 patients (30%) who had adjunctive balloon angioplasty. The overall angiographic restenosis rate was 37.8%. In conclusion, rotary ablation is technically feasible, and relatively safe i

Intact LKB1 activity is required for survival of dormant ovarian cancer spheroids

Metastatic epithelial ovarian cancer (EOC) cells can form multicellular spheroids while in suspension and disperse directly throughout the peritoneum to seed secondary lesions. There is growing evidence that EOC spheroids are key mediators of metastasis, and they use specific intracellular signalling pathways to control cancer cell growth and metabolism for increased survival. Our laboratory discovered that AKT signalling is reduced during spheroid formation leading to cellular quiescence and autophagy, and these may be defining features of tumour cell dormancy. To further define the phenotype of EOC spheroids, we have initiated studies of the Liver kinase B1 (LKB1)-5′-AMP-activated protein kinase (AMPK) pathway as a master controller of the metabolic stress response. We demonstrate that activity of AMPK and its upstream kinase LKB1 are increased in quiescent EOC spheroids as compared with proliferating adherent EOC cells. We also show elevated AMPK activity in spheroids isolated directly from patient ascites. Functional studies reveal that treatment with the AMP mimetic AICAR or allosteric AMPK activator A-769662 led to a cytostatic response in proliferative adherent ovarian cancer cells, but they fail to elicit an effect in spheroids. Targeted knockdown of STK11 by RNAi to reduce LKB1 expression led to reduced viability and increased sensitivity to carboplatin treatment in spheroids only, a phenomenon which was AMPK-independent. Thus, our results demonstrate a direct impact of altered LKB1-AMPK signalling function in EOC. In addition, this is the first evidence in cancer cells demonstrating a pro-survival function for LKB1, a kinase traditionally thought to act as a tumour suppressor