[The role of Wnt/ß-catenin/TCF-4 pathway on biological behavior of renal cell carcinoma and its mechanism].

Objective: To investigate the role of Wnt/ß-catenin/TCF-4 pathway in renal cancer cells and to analyze its possible mechanism. Methods: ß-catenin and TCF-4 were inhibited by siRNA in 786-O cells. The proliferation of transfected cells was detected by CCK8. The cell death of transfected cells was detected by acridine orange -ethidium bromide staining. The expressions of TCF-4, bcl-2, bax and Caspase-3 were detected in transfection group, empty vector group and negative control groups by western blot. Results: The cell proliferation ability of the ß-catenin transfection group was significantly lower than that of the control group (0.443±0.145 vs 0.910±0.721), meanwhile, the cell death rate was significantly increased (16.38±5.32 vs 6.61±1.04), the expression level of Caspase 3 and bax was increased, and the expression of anti-apoptotic protein Bcl-2 was decreased. Decreased TCF-4 led to the same results as inhibition of ß-catenin (all P<0.05). Conclusion: The Wnt/ß-catenin/TCF-4 pathway may play a role in the regulation of proliferation and apoptosis in 786-O renal cancer cells. The mechanism might through regulating of the downstream apoptosis proteins Caspase 3, bax and anti-apoptotic protein Bcl-2.

Long-term follow-up of arrhythmia characteristics and clinical outcomes in heart transplant patients.

INTRODUCTION: Arrhythmias occur frequently after heart transplantation (HT), but knowledge of their impact on long-term outcomes is limited. This study sought to investigate the characteristics of the arrhythmias among biatrial orthotopic HT patients during long-term follow-up. METHODS: This study included 217 patients who received biatrial orthotopic HT. Patients were classified into 5 groups according to the arrhythmia episodes that occurred >1 month after HT: no arrhythmias (group 1; n = 149); atrial tachyarrhythmias only (group 2; n = 34); ventricular tachyarrhythmias only (group 3; n = 9); bradyarrhythmias only (group 4; n = 7); or double/triple arrhythmias (group 5; n = 18). We analyzed their long-term outcomes respectively. RESULTS: During 83 ± 51 months of follow-up, all-cause mortality rates were higher in groups 3 (88.9%) and 5 (72.2%) compared with the other groups (groups 1, 2, and 4: 21.5%, 41.2%, and 57.1%, respectively; P < .001). Cardiovascular mortality rates were higher in groups 4 (42.9%) and 5 (61.1%) compared with the other groups (groups 1, 2, and 3: 8.1%, 20.6%, and 0% respectively; P < .001). Noncardiovascular mortality rate was greater in group 3 (88.9%) compared with the other groups (groups 1, 2, 4, and 5: 13.4%, 20.6%, 14.3%, and 11.1%, respectively; P < .001). Sudden death rates were higher in groups 4 (42.9%) and 5 (44.4%) compared with the other groups (groups 1, 2, and 3: 7.4%, 8.8%, and 0%, respectively; P < .001). CONCLUSION: Patients with posttransplantation arrhythmias experienced significantly worse clinical outcomes.

Electronic structure and characteristics of Fe 3d valence states of Fe(1.01)Se superconductors under pressure probed by x-ray absorption spectroscopy and resonant x-ray emission spectroscopy.

The electronic structure and characteristics of Fe 3d valence states of iron-chalcogenide Fe(1.01)Se superconductors under pressure were probed with x-ray absorption spectroscopy and resonant x-ray emission spectroscopy (RXES). The intensity of the pre-edge peak at ~7112.7 eV of the Fe K-edge x-ray absorption spectrum of Fe(1.01)Se decreases for pressure from 0.5 GPa increased to 6.9 GPa. The satellite line Kß' was reduced in intensity upon applying pressure and became absent for pressure 52 GPa. Fe(1.01)Se shows a small net magnetic moment of Fe(2+), likely arising from strong Fe-Fe spin fluctuations. The 1s3p-RXES spectra of Fe(1.01)Se at pressures 0.5, 6.9, and 52 GPa recorded at the Fe K-edge reveal that unoccupied Fe 3d states exhibit a delocalized character, stemming from hybridization of Fe 3d and 4p orbitals arising from a local distortion around the Fe atom in a tetrahedral site. Application of pressure causes suppression of this on-site Fe 3d-Fe 4p hybridization, and thereby decreases the intensity of the pre-edge feature in the Fe K-edge absorption spectrum of Fe(1.01)Se. Compression enhances spin fluctuations at Fe sites in Fe(1.01)Se and increases the corresponding T(c), through a competition between nearest-neighbor ferromagnetic and next-nearest-neighbor antiferromagnetic superexchange interactions. This result aids our understanding of the physics underlying iron-based superconductors.

Pressure-dependent electronic structures in multiferroic DyMnO(3): A combined lifetime-broadening-suppressed x-ray absorption spectroscopy and ab initio electronic structure study.

Variations in the electronic structure and structural distortion in multiferroic DyMnO(3) were probed by synchrotron x-ray diffraction, lifetime-broadening-suppressed x-ray absorption spectroscopy (XAS), and ab initio electronic structure calculations. The refined x-ray diffraction data enabled an observation of a diminished local Jahn-Teller distortion of Mn sites within MnO(6) octahedra in DyMnO(3) on applying the hydrostatic pressure. The intensity of the white line in Mn K-edge x-ray absorption spectra of DyMnO(3) progressively increased with the increasing pressure. With the increasing hydrostatic pressure, the absorption threshold of an Mn K-edge spectra of DyMnO(3) shifted toward a greater energy, whereas the pre-edge line slightly shifted to a smaller energy. We provide the spectral evidence for the pressure-induced bandwidth broadening for manganites. The intensity enhancement of the white line in Mn K-edge spectra is attributed to a diminished Jahn-Teller distortion of MnO(6) octahedra in compressed DyMnO(3). A comparison of the pressure-dependent XAS spectra with the ab initio electronic structure calculations and full calculations of multiple scattering using the code FDMNES shows the satisfactory agreement between experimental and calculated Mn K-edge spectra.

Swelling activated chloride currents in the electrical activity of pulmonary vein cardiomyocytes.

BACKGROUND: Pulmonary veins (PVs) contain cardiomyocytes with a high arrhythmogenicity for inducing atrial fibrillation. The swelling-activated outwardly rectifying Cl(-) currents (I(Cl,swell)) are important in the electrical activity of cardiomyocytes. This study was to investigate whether I(Cl,swell) play a role in the PV electrophysiological characteristics. MATERIALS AND METHODS: A whole-cell patch clamp was used to investigate the action potentials and I(Cl,swell) in isolated rabbit single PV and atrial cardiomyocytes during immersion in isotonic (290-300 mosm L(-1)) and hypotonic (220-230 mosm L(-1)) solutions. The cell length and cell width were measured using confocal microscopy. RESULTS: Hypotonic solution induced larger I(Cl,swell) in the PV cardiomyocytes with pacemaker activity than those in the PV cardiomyocytes without pacemaker activity or atrial cardiomyocytes. Hypotonic solution shortened the action potential duration and increased the cell width to a greater extent in the PV cardiomyocytes than in the atrial cardiomyocytes. Moreover, hypotonic solution decreased the PV firing with a decrease in the transient inward currents and delayed after depolarizations. CONCLUSIONS: These findings suggest that the I(Cl,swell) plays an important role in the electrical activity of the PV cardiomyocytes.

Effect of K201, a novel antiarrhythmic drug on calcium handling and arrhythmogenic activity of pulmonary vein cardiomyocytes.

BACKGROUND AND PURPOSE: Pulmonary veins are the most important focus for the generation of atrial fibrillation. Abnormal calcium homeostasis with ryanodine receptor dysfunction may underlie the arrhythmogenic activity in pulmonary veins. The preferential ryanodine receptor stabilizer (K201) possesses antiarrhythmic effects through calcium regulation. The purpose of this study was to investigate the effects of K201 on the arrhythmogenic activity and calcium regulation of pulmonary vein cardiomyocytes. EXPERIMENTAL APPROACH: The ionic currents and intracellular calcium were studied in isolated single cardiomyocytes from rabbit pulmonary vein before and after the administration of K201, by the whole-cell patch clamp and indo-1 fluorimetric ratio techniques. KEY RESULTS: K201 (0.1, 0.3, 1 microM) reduced the firing rates in pulmonary vein cardiomyocytes, decreased the amplitudes of the delayed afterdepolarizations and prolonged the action potential duration. K201 decreased the L-type calcium currents, Na(+)/Ca(2+) exchanger currents, transient inward currents and calcium transients. K201 (1 microM, but not 0.1 microM or 0.3 microM) also reduced the sarcoplasmic reticulum calcium content. Moreover, both the pretreatment and administration of K201 (0.3 microM) decreased the isoprenaline (10 nM)-induced arrhythmogenesis in pulmonary veins. CONCLUSIONS AND IMPLICATIONS: K201 reduced the arrhythmogenic activity of pulmonary vein cardiomyocytes and attenuated the arrhythmogenicity induced by isoprenaline. These findings may reveal the anti-arrhythmic potential of K201.

Supramolecular aggregation of regioregular poly(4-alkyl-2,6-quinoline)s.

Phase behavior and morphological features of regioregular, n-type semiconducting poly(4-alkyl-2,6-quinoline)s were examined in detail via a combination of thermal, microscopic, and diffraction methods. Two members (P4OQ and P4DQ, with n-octyl and n-decyl substitutions, respectively) in this series were selected as representatives. Results indicate the dominance of lamellar mesophase throughout the experimentally accessed temperature range (from ambient to above 300 degrees C), with lamellar spacing well-correlated with side-chain length and temperature. Optical textures observed via polarized light microscopy reveal clear domain-wall features in P4OQ but more solid-like characteristics for P4DQ; improved lamellar order was also observed for P4DQ as compared to P4OQ. These signify stronger tendency toward supramolecular self-assembly with increasing side-chain length. A model of molecular arrangement in the lamellar mesophase in which the free volume is identified as the gap between tips of extended (and interdigitated) side chains and the backbone of the neighboring chain is proposed to account for the observed variation of layer spacing with side-chain length and temperature. The presence of nanodomains (similar to those previously reported for p-type conjugated polymers) is also identified in the present n-type series, implying general existence of this inherent morphological heterogeneity in semiconducting hairy-rod polymers. This means that molecular aggregation is determined solely by ground-state intermolecular forces; differences in carrier transport characteristics are irrelevant during morphological development. Origins of these nanodomains are discussed in terms of backbone folding (via inherent chemical defects or elastic bending) as well as fringed-micelle aggregates.

Mechanoelectrical feedback regulates the arrhythmogenic activity of pulmonary veins.

BACKGROUND: Atrial fibrillation is commonly associated with dilated pulmonary veins. Stretch has been shown to have mechano-electrical effects. OBJECTIVE: To investigate whether stretch can increase the arrhythmogenic activity of the pulmonary veins. METHODS: The transmembrane action potentials were recorded from rabbit pulmonary veins before and after stretch (100 and 300 mg). Gadolinium and streptomycin (stretch-activated ion channel blockers) were each perfused into the pulmonary veins under a 300-mg stretch. RESULTS: Stretch (0, 100 and 300 mg) force dependently increased the incidence of spontaneous activity (22%, 48% and 83%; p<0.05), mean (standard deviation (SD)) firing rates of spontaneous activity (1.7 (0.2), 2.1 (0.3) and 3 (0.2) Hz; p<0.05) and incidence of early post-depolarisations (9%, 26% and 61%; p<0.05) and delayed post-depolarisations (0%, 4% and 30%; p<0.05) in 23 pulmonary veins. In the seven preparations with spontaneous activity after the 300-mg stretch, gadolinium (1, 3 and 10 mumol/l) decreased the incidence of spontaneous activity by 43%, 29% and 14%, respectively (p<0.05), and decreased the firing rate from 2.9 (0.1) Hz to 0.8 (0.4), 0.3 (0.1) and 0.1 (0.1) Hz, respectively (p<0.05). Streptomycin (10 and 40 mumol/l) decreased the incidence of spontaneous activity by 71% and 29%, respectively (p<0.05), and decreased the firing rate from 2.9 (0.1) Hz to 1.6 (0.4) and 0.5 (0.3) Hz, respectively (p<0.05). CONCLUSION: Stretch is an important factor in the electrical activity of the pulmonary vein. Stretch-induced arrhythmogenic activity of the pulmonary vein may contribute to the genesis of atrial fibrillation.

Phase behavior of poly(9,9-di-n-hexyl-2,7-fluorene).

Here we report the phase behavior of poly(9,9-di-n-hexyl-2,7-fluorene) (PFH), which previously received little attention as compared to its homologues poly(9,9-di-n-octyl-2,7-fluorene) (PFO) and poly(9,9-di-(2'-ethylhexyl)-2,7-fluorene) (PFEH). By means of differential scanning calorimetry, X-ray diffraction, and electron microscopy, we show that there exist four different phases in PFH. The as-cast film is mainly composed of a mesomorphic beta phase with layer spacing of ca. 1.4 nm. This beta phase is inherently metastable and, upon heating above 175 degrees C, transforms into a crystalline (alpha) form that melts into a nematic (N) liquid above 250 degrees C. Upon stepwise cooling, the nematic melt crystallizes into the alpha phase first, followed by solid-solid transformation into another crystalline (alpha') form. Unit cell structure of the alpha form is monoclinic whereas that of the alpha' form is triclinic, but departures from strict orthogonality are slight (by ca. 6 degrees). These observations not only support our previous assignment of two crystalline forms (both orthorhombic in structure) in PFO but also provide insights to the crystalline nature of the polyfluorene series.

A computerized apparatus designed to automatically dispense, measure, and record alcohol consumption by individual members of a rhesus macaque social group: trait-like drinking across social- and single-cage conditions.

BACKGROUND: The present study tested the validity of an automated ethanol dispensing apparatus that is capable of identifying individual monkeys and precisely measuring their levels of ethanol consumption while living in a social group, and assessed individual subjects' level of consumption when alone and in social groups. METHODS: In Experiment 1, 21 rhesus macaques (Macaca mulatta) were given access for 1-h each day to the dispensing apparatus, which contained an aspartame-sweetened 8.4% (v/v) ethanol solution. Measurements of blood ethanol concentrations were taken for each subject and compared with the level of consumption recorded by the apparatus for those subjects. To examine the possibility that competition among the animals limited their access to the dispensing unit, in Experiment 2, 10 of the subjects used in Experiment 1 were singly housed to allow them to drink without interference from other monkeys. A correlation was then performed to assess the interindividual relationship between the amount of ethanol consumed in these two housing conditions. RESULTS: In Experiment 1, the volume of solution measured and recorded by the apparatus correlated positively with the true volume dispensed. Furthermore, the volume of solution reported by the computer to have been consumed by an individual subject correlated positively with blood ethanol concentrations. In Experiment 2, the volume of ethanol consumed by individual subjects in single cages correlated positively with their consumption in the social group. CONCLUSIONS: The apparatus accurately identified and measured individual patterns of ethanol consumption among socially housed animals. Additionally, individual differences in ethanol consumption remained stable across settings, as shown by the strong positive correlation between drinking in a social setting versus drinking alone. This finding may thus reflect an individual's constitutional proclivity to consume alcohol.

Noncrystalline phases in poly(9,9-di-n-octyl-2,7-fluorene).

Selective formation of amorphous, nematic (N), and beta phases in poly(9,9-di-n-octyl-2,7-fluorene) (PFO) films was achieved via judicious choice of process parameters. Phase structure and film morphology were carefully examined by means of X-ray diffraction as well as electron microscopy. "Amorphous" thin films were obtained by quick evaporation of solvent. Slow solvent removal during film formation or extended treatment of the amorphous film with solvent vapor resulted in predominantly the beta phase, which corresponds to a frozen (due to decreased segmental mobility upon solvent removal) and intrinsically metastable state of transformation midway between a solvent-induced clathrate phase and the equilibrium crystalline order in the undiluted state. The frozen transformation process is reactivated upon an increase in temperature beyond 100 degrees C. Compared to the amorphous film, extended backbone conjugation in the beta phase is evidenced from the emergence of a characteristic absorption peak around 430 nm near the absorption edge. For films of frozen nematic order (obtained by quenching from the nematic state), the conjugation length is also greater than the amorphous films as revealed by an absorption shoulder around 420 nm. Well-behaved single-chromophore emission with single-mode phonon coupling was observed for the beta phase; in the case of nematic films, dual-mode phonon coupling must exist if single-chromophore emission is assumed. In comparison, the emission spectrum of the amorphous film of generally shorter conjugation lengths exhibited mixed characteristics of nematic and beta phases, implying the presence of minor populations of extended conjugation similar to those in nematic and beta phases, which are of biased weightings in the emission spectra. All these films consist of nanograins (ca. 10 nm in size) of collapsed chains; the films are therefore inherently inhomogeneous in this length scale. In combination with previous observations on the crystalline (alpha and alpha') forms, the phase behavior of PFO is then generally summarized in terms of relative thermodynamic stability.

Aging of poly(2-methoxy-5-(2'-ethylhexyloxy)-1,4-phenylenevinylene)/toluene solutions and subsequent effects on luminescence behavior of cast films.

Morphological effects in luminescence properties of a representative semiconducting polymer, poly(2-methoxy-5-(2'-ethylhexyloxy)-1,4-phenylenevinylene) (MEH-PPV), has recently attracted much attention. Previous studies indicated that short-term heat treatment of solution-cast MEH-PPV films may result in the formation of mesomorphic order that is responsible for the "red" emission around 640 nm, in contrast to the single-chromophore "yellow" emission near 590 nm from the disordered matrix. On the basis of microscopic and spectroscopic evidence for films cast from freshly prepared and aged solutions, here we show that prolonged storage of MEHyellowPPV solutions at room temperature or lower may result in retardation of the thermally induced mesophase formation in the subsequently cast films. According to small-angle neutron scattering and differential scanning calorimetric observations over aged MEH-PPV/toluene solutions, we propose that the suppressed transformation into mesomorphic order is due to further development of nanocrystalline aggregates that serve as physical cross-links among MEH-PPV chains in the solution state upon long-term storage. These solvent-induced nanocrystalline aggregates, however, do not exhibit new spectroscopic features beyond the suppression of "red" emission at 640 nm from the mesomorphic phase.

Triplet-to-singlet exciton formation in poly(p-phenylene-vinylene) light-emitting diodes.

The triplet to singlet exciton formation ratio in a MEH-PPV light-emitting diode is measured by comparing the triplet-induced absorptions with optical and electric excitations at the same singlet exciton density. The ratio is a strong universal decreasing function of the averaged electric field. Using 4 ns for singlet to triplet intersystem crossing time, the ratio is significantly larger than the spin-independent value 3 at intermediate field but is reduced to about 2 for higher field.

Clinical and electrophysiological characteristics in children with atrioventricular nodal reentrant tachycardia.

Atrioventricular (AV) nodal reentrant tachycardia is one of the most common supraventricular tachycardias in childhood. However, information about AV nodal reentrant tachycardia in childhood is limited, especially about the variant and multiple forms. The purpose of this retrospective study was to investigate the clinical and electrophysiological characteristics in pediatric patients with AV nodal reentrant tachycardia. Forty-eight pediatric patients with AV nodal reentrant tachycardia were included (ages 11-18 years; 25 males and 23 females). The age of onset and duration of symptoms were significantly younger and shorter in pediatric patients, respectively. A higher incidence of antegrade dual AV nodal pathways was found in adult patients than pediatric patients (72.9 vs 52.1% p = 0.003). Both antegrade and retrograde slow pathway functions were better in pediatric than adult patients. There was no significant difference between children and adults in the occurrence of variant and multiple forms of AV nodal reentrant tachycardia. This study demonstrated that pediatric patients have different electrophysiologic characteristics from those of adult patients.

Stimulation of the BK(Ca) channel in cultured smooth muscle cells of human trachea by magnolol.

BACKGROUND: Magnolol, a compound isolated from the cortex of Magnolia officinalis, has been found to possess anti-allergic and anti-asthmatic activity. METHODS: The effect of magnolol on ionic currents was studied in cultured smooth muscle cells of human trachea with the aid of the patch clamp technique. RESULTS: In whole cell current recordings magnolol reversibly increased the amplitude of K+ outward currents. The increase in outward current caused by magnolol was sensitive to inhibition by iberiotoxin (200 nM) or paxilline (1 microM) but not by glibenclamide (10 microM). In inside out patches, magnolol added to the bath did not modify single channel conductance but effectively enhanced the activity of large conductance Ca2+ activated K+ (BK(Ca)) channels. Magnolol increased the probability of these channel openings in a concentration dependent manner with an EC50 value of 1.5 microM. The magnolol stimulated increase in the probability of channels opening was independent of internal Ca2+. The application of magnolol also shifted the activation curve of BK(Ca) channels to less positive membrane potentials. The change in the kinetic behaviour of BK(Ca) channels caused by magnolol in these cells is the result of an increase in dissociation and gating constants. CONCLUSIONS: These results provide evidence that, in addition to the presence of antioxidative activity, magnolol is potent in stimulating BK(Ca) channel activity in tracheal smooth muscle cells. The direct stimulation of these BK(Ca) channels by magnolol may contribute to the underlying mechanism by which it acts as an anti-asthmatic compound.

Effects of rapid atrial pacing on the arrhythmogenic activity of single cardiomyocytes from pulmonary veins: implication in initiation of atrial fibrillation.

BACKGROUND: Pulmonary veins (PVs) are important sources of paroxysmal atrial fibrillation. Long-term rapid atrial pacing (RAP) changes atrial electrophysiology and facilitates the maintenance of atrial fibrillation. It is not clear whether RAP alters the arrhythmogenic activity of PVs. The purpose of this study was to isolate single PV cardiomyocytes from control and RAP dogs and evaluate their electrophysiological characteristics. METHODS AND RESULTS: The action potential and ionic currents were investigated in PV cardiomyocytes from control and long-term (6 to 8 weeks) RAP (780 bpm) dogs by use of the whole-cell clamp technique. Dissociation of PVs yielded rod-shaped single cardiomyocytes without (n=91, 60%) or with (n=60, 40%) pacemaker activity. Compared with the control group, the RAP dog PV cardiomyocytes had faster beating rates (0.86+/-0.28 versus 0.45+/-0.07 Hz, P<0.05) and shorter action potential duration. The RAP dog PV cardiomyocytes with pacemaker activity have a higher incidence of delayed (59% versus 7%, P<0.001) or early (24% versus 0%, P<0.005) after depolarization. The RAP dog PV cardiomyocytes with pacemaker activity had smaller slow inward and transient outward but larger transient inward (0.017+/-0.004 versus 0.009+/-0.002 pA/pF, P<0.05) and pacemaker (0.111+/-0.019 versus 0.028+/-0.008 pA/pF, P<0.001) currents. The RAP dog PV cardiomyocytes without pacemaker activity had only smaller slow inward and transient outward and larger pacemaker currents. CONCLUSIONS: PVs contain multiple cardiomyocytes with distinct electrophysiological characteristics. RAP changes the electrophysiological characteristics and arrhythmogenic activity of PVs.

Heterogeneity of myocardial sleeve morphology and gap junctions in canine superior vena cava.

BACKGROUND: The myocardial sleeve of the superior vena cava (SVC) has been identified as a potential initiating focus in atrial fibrillation, but information on cell-to-cell linkage at this site is lacking. METHODS AND RESULTS: We examined the SVC in 8 dogs by immunoconfocal and electron microscopy. Cardiomyocytes outlined with vinculin and bearing striations positive for alpha-actinin are found in the proximal segment of the SVC. These cells, grouped in bundles of various orientations according to location, extend cephalically as far as 3 cm from the right atrium (RA)-SVC junction. Comparison between the junctional level and the level 2 cm distal shows that the myocardial layer in the latter is thinner and not as compact and is composed of longer cells (87.3+/-15.7 versus 71.6+/-14.4 micrometer, P<0.01). Gap junctions made of connexin43 (Cx43), Cx40, and Cx45 are aggregated mainly at the intercalated disks, and colocalization of connexins is a common feature throughout the myocardial sleeve. Areas of atypical expression exist, however, characterized by a center of abundant Cx43 labels surrounded by a periphery of scattered tiny Cx40-labeled spots. Although in the ventral subluminal compact myocardial layer, individual cells at both levels are surrounded by similar numbers of cells, the number of aggregation of labeled gap junctions at the distal level is less (2.3+/-0.6 versus 3.7+/-0.9, P<0.01). In addition, electron-microscopic examination demonstrates that the gap junctions at the distal level are smaller in size (0.37+/-0.30 versus 0.55+/-0.34 micrometer, P<0.01). CONCLUSIONS: The myocardial sleeve in the canine SVC is a heterogeneous structure, which could potentially form a substrate for heterogeneity of electrical coupling.