[Pathological study on the relationship between nucleic acid oxidative stress and heart failure with preserved ejection fraction in patients aged over 85 years]

Objective: To investigate the level of nucleic acid oxidation in myocardial tissue of patients aged over 85 with heart failure with preserved ejection fraction (HFpEF) and the correlation with myocardial amyloid deposition. Methods: This was a retrospective case-control study. Data of patients≥85 years old who underwent systematic pathological autopsy in Beijing Hospital from 2003 to 2017 were retrospectively collected. Twenty-six patients were included in the HFpEF group and 13 age-and sex-matched patients who had not been diagnosed with heart failure and died of non-cardiovascular diseases served as the control group. The left ventricular myocardium slices of both groups were semi-quantitatively analyzed using immunohistochemical staining of 8-oxidized guanine riboside (8-oxo-G) and 8-oxidized guanine deoxyriboside (8-oxo-dG) to evaluate the oxidation of RNA and DNA in cardiomyocytes. Using the median of the mean absorbance value of 8-oxo-G immunohistochemical staining as the cut-off value, patients were divided into high-absorbance group and low-absorbance group. Congo red staining was used to compare myocardial amyloid deposition between the two groups. Results: The mean age of patients in HFpEF group was (91.8±3.7) years, 24 (92.3%) were males. The mean age of patients in control group was (91.7±3.7) years old, 11 (84.6%) were males. The median mean optical absorbance value of 8-oxo-G immunohistochemical staining of myocardium was significantly higher in HFpEF patients than in control group (0.313 8 (0.302 2, 0.340 6) vs. 0.289 2 (0.276 7, 0.299 4), Z=-3.245, P=0.001). The median mean absorbance value of 8-oxo-dG immunohistochemical staining of myocardial tissue was similar between the two groups (0.300 0 (0.290 0, 0.322 5) vs. 0.300 0 (0.290 0, 0.320 0), Z=-0.454, P=0.661). Proportion of patients with moderate and severe cardiac amyloid deposition was significantly higher in the high-absorbance group than in the low-absorbance group ((85.0%, 17/20) vs. (31.6%, 6/19), P=0.001). Conclusion: The RNA oxidation degree of myocardium in HFpEF patients is higher than that in elderly people without heart failure. Degree of myocardial amyloid deposits is higher in patients with high levels of RNA oxidation.

Spin ice: magnetic excitations without monopole signatures using muon spin rotation

Theory predicts the low temperature magnetic excitations in spin ices consist of deconfined magnetic charges, or monopoles. A recent transverse-field (TF) muon spin rotation (μSR) experiment [S. T. Bramwell et al., Nature (London) 461, 956 (2009)] reports results claiming to be consistent with the temperature and magnetic field dependence anticipated for monopole nucleation-the so-called second Wien effect. We demonstrate via a new series of μSR experiments in Dy(2)Ti(2)O(7) that such an effect is not observable in a TF μSR experiment. Rather, as found in many highly frustrated magnetic materials, we observe spin fluctuations which become temperature independent at low temperatures, behavior which dominates over any possible signature of thermally nucleated monopole excitations.

Giant anharmonic phonon scattering in PbTe

Understanding the microscopic processes affecting the bulk thermal conductivity is crucial to develop more efficient thermoelectric materials. PbTe is currently one of the leading thermoelectric materials, largely thanks to its low thermal conductivity. However, the origin of this low thermal conductivity in a simple rocksalt structure has so far been elusive. Using a combination of inelastic neutron scattering measurements and first-principles computations of the phonons, we identify a strong anharmonic coupling between the ferroelectric transverse optic mode and the longitudinal acoustic modes in PbTe. This interaction extends over a large portion of reciprocal space, and directly affects the heat-carrying longitudinal acoustic phonons. The longitudinal acoustic-transverse optic anharmonic coupling is likely to play a central role in explaining the low thermal conductivity of PbTe. The present results provide a microscopic picture of why many good thermoelectric materials are found near a lattice instability of the ferroelectric type.

Early embryonic blood cells collect antigens and induce immunotolerance in the hatched chicken

Earlier experimental data in our laboratory showed that introduction of an exogenous protein into early chicken embryonic blood leads to immunotolerance of hatched chicken to that protein. However, the underlying mechanism is yet unknown. In the present study, we show that the blood cells collecting circulating antigen might contribute to the establishment of immunotolerance. In this experiment, most of the chicken embryo blood cells took up injected fluorescein isothiocyanate-BSA at approximately embryonic d 3. At the same stage, 1 microL of embryo blood was taken out and incubated with BSA. After being loaded with BSA in vitro and washed, these cells were injected back into the original embryo. The BSA-specific lymphocytes were depleted in chickens whose early embryo cells had been loaded with BSA, as evidenced by a significant decrease in anti-BSA antibody after challenge with BSA when the chickens were 3 wk old. In addition, by direct injection of BSA to embryonic d 3 embryo blood, the hatched chickens had decreased amounts of anti-trinitrophenol antibody after the chickens were challenged with trinitrophenol-BSA, indicating that the helper function of BSA-specific T cells was impaired. In conclusion, these observations suggest that some early embryo blood cells possibly collect and store antigen for the establishment of self-tolerance before the maturation of B and T cells.

Unconventional superconductivity with a sign reversal in the order parameter of LaFeAsO1-xFx

We argue that the newly discovered superconductivity in a nearly magnetic, Fe-based layered compound is unconventional and mediated by antiferromagnetic spin fluctuations, though different from the usual superexchange and specific to this compound. This resulting state is an example of extended s-wave pairing with a sign reversal of the order parameter between different Fermi surface sheets. The main role of doping in this scenario is to lower the density of states and suppress the pair-breaking ferromagnetic fluctuations.

Density functional study of LaFeAsO(1-x)F(x): a low carrier density superconductor near itinerant magnetism

Density functional studies of 26 K superconducting LaFeAs(O,F) are reported. We find a low carrier density, high density of states, N(E(F)), and modest phonon frequencies relative to T(c). The high N(E(F)) leads to proximity to itinerant magnetism, with competing ferromagnetic and antiferromagnetic fluctuations and the balance between these controlled by the doping level. Thus LaFeAs(O,F) is in a unique class of high T(c) superconductors: high N(E(F)) ionic metals near magnetism.

Coherent electron transport through an azobenzene molecule: a light-driven molecular switch

We apply a first-principles computational approach to study a light-sensitive molecular switch. The molecule that comprises the switch can convert between a trans and a cis configuration upon photoexcitation. We find that the conductance of the two isomers varies dramatically, which suggests that this system has potential application as a molecular device. A detailed analysis of the band structure of the metal leads and the local density of states of the system reveals the mechanism of the switch.

The recognition of three different epitopes for the H-type 2 human blood group determinant by lectins of Ulex europaeus, Galactia tenuiflora and Psophocarpus tetragonolobus (winged bean)

The chemical mapping of the regions of H-type 2 human blood group-related trisaccharide (Fuc alpha (1-2)Gal beta (1-4)GlcNAc beta Me) that are recognized by three different lectins, the so-called epitopes, are reviewed together with an account of how and why oligosaccharides form specific complexes with proteins as presently viewed in this laboratory. The occasion is used to report the synthesis of the various mono-O-methyl derivatives of the above trisaccharide that were used in these investigations. Also, Fuc alpha (1-2)Gal beta (1-4)Xyl beta Me was synthesized in order to examine whether or not the hydroxymethyl group of the GlcNAc residue participates in the binding reaction.

Measurement of human BAERs by the maximum length sequence technique

The traditional brainstem auditory evoked response (BAER) measurement technique (ensemble averaging) is time-consuming and is not acceptable for some time-critical clinical applications. In the paper the application of a pseudorandom binary sequence, the maximum length sequence, to human BAER measurements is examined. This technique permits a faster click rate to stimulate the test subject, and obtains a higher signal-to-noise ratio (SNR) response through deconvolution. When compared with conventional averaging, the method can result in an improved SNR or in faster measurement of BAER. The theory of the technique and the experimental setup are presented, and theoretical analysis on the SNR improvement by this technique against averaging is also given. Actual measurements of BAER on both humans and cats indicate that this technique is effective, especially when the measurement time is not too long, or the number of trials is not too large.

Visual evoked potential measurement by maximum length sequence technique

The maximum length sequence (MLS) technique is applied to improve data collection of a clinically important long latency visual potential. Given a limited time for measuring the response and with low number of stimulus presentation, the MLS technique exceeded the conventional method of ensemble averaging in attaining a higher signal-to-noise ratio (SNR). The theoretical consideration of such improvement is developed along with the system implementation. Typical examples of the results obtained in a human subject are presented.