Quantum phase transition in magnetic nanographenes on a lead superconductor

Quantum spins, referred to the spin operator preserved by full SU(2) symmetry in the absence of the magnetic anistropy, have been proposed to host exotic interactions with superconductivity4. However, spin orbit coupling and crystal field splitting normally cause a significant magnetic anisotropy for d/f-shell spins on surfaces6,9, breaking SU(2) symmetry and fabricating the spins with Ising properties10. Recently, magnetic nanographenes have been proven to host intrinsic quantum magnetism due to their negligible spin orbital coupling and crystal field splitting. Here, we fabricate three atomically precise nanographenes with the same magnetic ground state of spin S=1/2 on Pb(111) through engineering sublattice imbalance in graphene honeycomb lattice. Scanning tunneling spectroscopy reveals the coexistence of magnetic bound states and Kondo screening in such hybridized system. Through engineering the magnetic exchange strength between the unpaired spin in nanographenes and cooper pairs, quantum phase transition from the singlet to the doublet state has been observed, in consistent with quantum models of spins on superconductors. Our work demonstrates delocalized graphene magnetism host highly tunable magnetic bound states with cooper pairs, which can be further developed to study the Majorana bound states and other rich quantum physics of low-dimensional quantum spins on superconductors.Comment: 13 pages, 4figure

Diabetes increases mortality after myocardial infarction by oxidizing CaMKII

Diabetes increases oxidant stress and doubles the risk of dying after myocardial infarction, but the mechanisms underlying increased mortality are unknown. Mice with streptozotocin-induced diabetes developed profound heart rate slowing and doubled mortality compared with controls after myocardial infarction. Oxidized Ca(2+)/calmodulin-dependent protein kinase II (ox-CaMKII) was significantly increased in pacemaker tissues from diabetic patients compared with that in nondiabetic patients after myocardial infarction. Streptozotocin-treated mice had increased pacemaker cell ox-CaMKII and apoptosis, which were further enhanced by myocardial infarction. We developed a knockin mouse model of oxidation-resistant CaMKIIδ (MM-VV), the isoform associated with cardiovascular disease. Streptozotocin-treated MM-VV mice and WT mice infused with MitoTEMPO, a mitochondrial targeted antioxidant, expressed significantly less ox-CaMKII, exhibited increased pacemaker cell survival, maintained normal heart rates, and were resistant to diabetes-attributable mortality after myocardial infarction. Our findings suggest that activation of a mitochondrial/ox-CaMKII pathway contributes to increased sudden death in diabetic patients after myocardial infarction

A Dynamic Pathway for Calcium-Independent Activation of CaMKII by Methionine Oxidation

SummaryCalcium/calmodulin (Ca2+/CaM)-dependent protein kinase II (CaMKII) couples increases in cellular Ca2+ to fundamental responses in excitable cells. CaMKII was identified over 20 years ago by activation dependence on Ca2+/CaM, but recent evidence shows that CaMKII activity is also enhanced by pro-oxidant conditions. Here we show that oxidation of paired regulatory domain methionine residues sustains CaMKII activity in the absence of Ca2+/CaM. CaMKII is activated by angiotensin II (AngII)-induced oxidation, leading to apoptosis in cardiomyocytes both in vitro and in vivo. CaMKII oxidation is reversed by methionine sulfoxide reductase A (MsrA), and MsrA−/− mice show exaggerated CaMKII oxidation and myocardial apoptosis, impaired cardiac function, and increased mortality after myocardial infarction. Our data demonstrate a dynamic mechanism for CaMKII activation by oxidation and highlight the critical importance of oxidation-dependent CaMKII activation to AngII and ischemic myocardial apoptosis

Dietary Supplementation of Ancientino Ameliorates Dextran Sodium Sulfate-Induced Colitis by Improving Intestinal Barrier Function and Reducing Inflammation and Oxidative Stress

Ancientino, a complex dietary fiber supplement mimicking the ancient diet, has improved chronic heart failure, kidney function, and constipation. However, its effect on ulcerative colitis is unknown. This study explores the impact of Ancientino on colitis caused by dextran sulfate sodium (DSS) and its mechanisms. Data analyses showed that Ancientino alleviated bodyweight loss, colon shortening and injury, and disease activity index (DAI) score, regulated levels of inflammatory factors (tumor necrosis factor-alpha (TNF-α), interleukin-10 (IL-10), interleukin-1 beta (IL-1β), and interleukin 6 (IL-6)), reduced intestinal permeability (d-lactate and endotoxin), fluorescein isothiocyanate–dextran (FITC-dextran), and diamine oxidase (DAO), repaired colonic function (ZO-1 and occludin), and suppressed oxidative stress (superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px), and malondialdehyde (MDA)) in vivo and in vitro. In short, this study demonstrated that Ancientino alleviates colitis and exerts an anticolitis effect by reducing inflammatory response, suppressing oxidative stress, and repairing intestinal barrier function. Thus, Ancientino may be an effective therapeutic dietary resource for ulcerative colitis

Detection of HLA-B{*}58: 01 with TaqMan assay and its association with allopurinol-induced sCADR

Background: The HLA-B{*}58:01 allele is associated with allopurinol-induced severe cutaneous adverse drug reactions (sCADR) in certain geographic regions, but the diversity of the correlation is large. In addition, the currently available HLA-B{*}58:01 testing methods are too laborious for use in routine clinical detection. The objective of this study was to develop a new, convenient method for the detection of HLA-B{*}58:01 and to investigate the association of HLA-B{*}58: 01 with allopurinol-induced sCADR in a Han Chinese population. Methods: A new method combining sequence-specific primers (SSP) and TaqMan probe amplification was developed in this study and was used to detect the HLA-B{*}58:01 in 48 allopurinol-induced sCADR, 133 allopurinol-tolerant, and 280 healthy individuals. The accuracy, sensitivity, and specificity were assessed by a commercial PCR-SSP HLA-B typing kit. The low limit of detection was detected by serial dilution of an HLA-B{*}58:01-positive DNA template. Results: The new method successfully identified HLAB{*}58: 01 in thousands of HLA-B alleles, and the results for 344 DNA samples were perfectly concordant with the results of the commercial PCR-SSP HLA-B kit. The analytical sensitivity is 100% and the specificity is over 99%. The low limit of detection of this assay is 100 pg DNA, which was 10 times more sensitive than the commercial PCR-SSP kit. HLA-B{*}58:01 was present in 93.8% of the patients with sCADR, 7.5% of the allopurinol-tolerant patients, and 12.1% of the healthy controls. The frequency of HLAB{*} 58: 01 was significantly higher in the sCADR group than in the control group (p < 0.0001). However, there was no significant difference between the allopurinol-tolerant and control groups (p = 0.1547). Conclusions: HLA-B{*}58:01 has a strong association with allopurinol-induced sCADR in Han Chinese. The newly developed method is reliable for HLA-B{*}58:01 detection prior to allopurinol therapy