The reaction of Bppy(Mes)2 (BN1; ppy = 2-phenylpyridine) and BCH2ppy(Mes)2 (BN3) with the reducing reagent KC8 resulted in C-C bond formation via intermolecular radical coupling to generate the 4,4'-bipyridyl ligand compounds BN2 and BN4. Adding 1 equivalent of KC8 to a THF solution of BN2 and BN4 generated the 4,4'-bipyridyl radical anions BN2K and BN4K. The dianion species BN2K2 and BN4K2 could be obtained by adding 2 equivalents of KC8 to the THF solution of BN2 and BN4. In the presence of 2,2,2-cryptand or 18-crown-6, the radical anion salt BN2K(crypt) and the dianion salt BN2K2(18c6)2 were isolated for single-crystal X-ray diffraction analysis. Structural, spectroscopic, and computational studies were performed on the three species of BN2 derivatives (neutral, radical anion, and dianion species). BN2 and BN4 were stable and did not undergo photoisomerization or photoelimination under UV light irradiation.
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The reduction of 2,4,6-tri(4-pyridyl)-1,3,5-triazine (TPT) with alkali metals resulted in four radical anion salts (1, 2, 4 and 5) and one diradical dianion salt (3). Single-crystal X-ray diffraction and electron paramagnetic resonance (EPR) spectroscopy reveal that 1 contains the monoradical anion TPT.- stacked in one-dimensional (1D) with K+ (18c6) and 2 can be viewed as a 1D magnetic chain of TPT.- , while 4 and 5 form radical metal-organic frameworks (RMOFs). 1D pore passages, with a diameter of 6.0 Å, containing solvent molecules were observed in 5. Variable-temperature EPR measurements show that 3 has an open-shell singlet ground state that can be excited to a triplet state, consistent with theoretical calculation. The work suggests that the direct reduction approach could lead to the formation of RMOFs.
Abstract The first main‐group element radical based one‐dimensional magnetic chain ( 1K ) n was realized by one‐electron reduction of the pyridinyl functionalized borane 1 with elemental potassium in THF in the absence of 18‐crown‐6 (18‐c‐6). The electron spin density of ( 1K ) n mainly resides at the boron centers with a considerable contribution from central benzene and pyridine moieties. The spin centers exhibit an antiferromagnetic interaction as demonstrated by magnetic measurements and theoretical calculations. In contrast, the reduction in the presence of 18‐c‐6 afforded the separated radical anion salt 1K(Crown) , in which the potassium cation was trapped by THF and 18‐c‐6 molecules. Further one‐electron reduction of 1K(Crown) and ( 1K ) n led to the diamagnetic monomer and polymer, respectively.
ABSTRACT BACKGROUND N-terminal-acetyltransferases catalyze N-terminal acetylation (Nt-acetylation), an evolutionarily conserved co-translational modification. Nt-acetylation regulates diverse signaling pathways, yet little is known about its effects in the heart. To gain insights, we studied NAA10-related syndrome, in which mutations in NAA10, which catalyzes Nt-acetylation, causes severe QT prolongation, hypotonia, and neurodevelopmental delay. METHODS We identified a missense variant in NAA10 (c.10C>A; p.R4S) that segregated with severe QT prolongation, arrhythmia, cardiomyopathy, and sudden death in a large kindred. We developed patient-derived and genome-edited human induced pluripotent stem cell (iPSC) models and deeply phenotyped iPSC-derived cardiomyocytes (iPSC-CMs) to dissect the mechanisms underlying NAA10-mediated cardiomyocyte dysfunction. RESULTS The NAA10-R4S mutation reduced enzymatic activity, decreased expression levels of NAA10/NAA15 proteins, and destabilized the NatA complex. In iPSC-CM models of NAA10 dysfunction, dysregulation of the late sodium and slow rectifying potassium currents caused severe repolarization abnormalities, consistent with clinical QT prolongation and increased risk for arrhythmogenesis. Engineered heart tissues generated from mutant NAA10 cell lines had significantly decreased contractile force and sarcomeric disorganization, consistent with the cardiomyopathic phenotype in the identified family members. Diastolic calcium levels were increased with corresponding alterations in calcium handling pathways. We identified small molecule and genetic therapies that reversed the effects of NAA10 dysregulation of iPSC-CMs. CONCLUSIONS Our study defines novel roles of Nt-acetylation in cardiac ion channel regulation and delineates mechanisms underlying QT prolongation, arrhythmia, and cardiomyopathy caused by NAA10 dysfunction.
To prepare and study the biocompatibility of selectively decellular xenoskin which has the character of the lower antigen, continuous epidermis, and the dermal matrix without any cellular components.The porcine skin was treated with glutaraldehyde solution, trypsin, and detergent solution TritonX-100 to prepare the selectively decellular xenoskin. The cytotoxicity was tested according to GB/T16886.5-2003 biological evaluation of medical devices for in vitro cytotoxicity, and the levels of cytotoxicity were evaluated with the United States Pharmacopeia. Subdermal implantation was tested according to GB/T16886.6-1997 biological evaluation of medical devices for local effects after implantation. Seventy-two mature Wistar rats were randomly assigned to groups A, B, and C (n = 24). Three kinds of materials were implanted into subcutaneous of rats back. Selectively decellular xenoskin was transplanted into group A, fresh porcine skin was transplanted into group B, and allogeneic skin was transplanted into group C. The samples were collected to make the observation of gross and histology after 1, 2, 4, 8, 12, and 16 weeks.The cytotoxicity was proved to be first grade by biocompatibility test. The gross and histological observation of subdermal implantation: after implantation, the most severe inflammatory reactions were seen in group B which dispersion was very slow. Inflammatory reactions in groups A and C alleviated gradually. In groups A and C, there was an increased collagen fiber density and angiogenesis at late stage; the transplanted skin was gradually degraded and absorbed. In group B, no obvious degradation and absorption were observed.Selectively decellular xenoskin, prepared with glutaraldehyde solution, trypsin, and detergent solution, possesses characteristics of integral skin structure and excellent biocompatibility, so it can be used as a new type substitute to repair the burn wound.
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