[Research progress in the regulation of autophagy and mitochondrial homeostasis by AMPK signaling channels].

AMP-activated protein kinase (AMPK) is a widely distributed and evolutionarily conserved serine/threonine protein kinase present in eukaryotic cells. In regulating cellular energy metabolism, AMPK plays an extremely important role as an energy metabolic kinase. When the body is in a low energy state, AMPK is activated in response to changes in intracellular adenine nucleotide levels and is bound to adenosine monophosphate (AMP) or adenosine diphosphate (ADP). Activated AMPK regulates various metabolic processes, including lipid and glucose metabolism and cellular autophagy. AMPK directly promotes autophagy by phosphorylating autophagy-related proteins in the mammalian target of rapamycin complex 1 (mTORC1), serine/threonine protein kinase-dysregulated 51-like kinase 1 (ULK1) and type III phosphatidylinositol 3-kinase-vacuolar protein-sorting 34 (PIK3C3-VPS34) complexes. AMPK also indirectly promotes autophagy by regulating the expression of downstream autophagy-related genes of transcription factors such as forkhead box O3 (FOXO3), lysosomal function transcription factor EB (TFEB) and bromodomain protein 4 (BRD4). AMPK also regulates mitochondrial autophagy, induces the division of damaged mitochondria and promotes the transfer of the autophagic response to damaged mitochondria. Another function of AMPK is to regulate mitochondrial health by stimulating mitochondrial biogenesis and participating in various aspects of mitochondrial homeostasis regulation. This review discusses the specific regulation of mitochondrial biology and internal environmental homeostasis by AMPK signaling channels as central to the cellular response to energy stress and regulation of mitochondria, highlighting the key role of AMPK in regulating cellular autophagy and mitochondrial autophagy, as well as advances in research on the regulation of mitochondrial homeostasis.

Volume overload impedes the maturation of sarcomeres and T-tubules in the right atria: a potential cause of atrial arrhythmia following delayed atrial septal defect closure.

Introduction: Adult patients with atrial septal defects (ASD), the most common form of adult congenital heart disease, often die of arrhythmias, and the immaturity of cardiomyocytes contributes significantly to arrhythmias. ASD typically induces a left-to-right shunt, which then leads to the right atrium (RA) volume overload (VO). Whether or not VO contributes to RA cardiomyocyte immaturity and thereby causes arrhythmias in adult patients with ASD remains unclear. Methods: Here, we developed the first neonatal RA VO mouse model by creating a fistula between the inferior vena cava and abdominal aorta on postnatal day 7. RA VO was confirmed by increases in the mean flow velocity, mean pressure gradient, and velocity time integral across the tricuspid valve, and an increase in the RA diameter and RA area middle section. Results: We found that VO decreased the regularity and length of sarcomeres, and decreased the T-element density, regularity, and index of integrity of T-tubules in RA cardiomyocytes, suggesting that the two most important maturation hallmarks (sarcomere and T-tubules) of RA cardiomyocytes were impaired by VO. Accordingly, the calcium handling capacity of cardiomyocytes from postnatal day 21 (P21) RA was decreased by VO. VO caused a significant elongation of the PR interval. The expression of connexin 43 (Cx43) was decreased in RA VO. Moreover, gene ontology (GO) analysis of the downregulated genes in RA demonstrated that there was an abundance of enriched terms associated with sarcomeres and T-tubules exposed to VO. The results were further verified by qRT-PCR. Conclusions: In conclusion, the first neonatal RA VO mouse model was developed; furthermore, using this neonatal RA VO mouse model, we revealed that VO impeded RA sarcomere and T-tubule maturation, which may be the underlying causes of atrial arrhythmias in adult patients with ASD.

Synthetic control of correlated disorder in UiO-66 frameworks.

Changing the perception of defects as imperfections in crystalline frameworks into correlated domains amenable to chemical control and targeted design might offer opportunities for the design of porous materials with superior performance or distinctive behavior in catalysis, separation, storage, or guest recognition. From a chemical standpoint, the establishment of synthetic protocols adapted to control the generation and growth of correlated disorder is crucial to consider defect engineering a practicable route towards adjusting framework function. By using UiO-66 as experimental platform, we systematically explored the framework chemical space of the corresponding defective materials. Periodic disorder arising from controlled generation and growth of missing cluster vacancies can be chemically controlled by the relative concentration of linker and modulator, which has been used to isolate a crystallographically pure "disordered" reo phase. Cs-corrected scanning transmission electron microscopy is used to proof the coexistence of correlated domains of missing linker and cluster vacancies, whose relative sizes are fixed by the linker concentration. The relative distribution of correlated disorder in the porosity and catalytic activity of the material reveals that, contrarily to the common belief, surpassing a certain defect concentration threshold can have a detrimental effect.

Ferric Single-Site Catalyst Confined in a Zeolite Framework for Propane Dehydrogenation.

Non-oxidative dehydrogenation of propane is a highly efficient approach for industrial preparation of propene that is commonly catalyzed by noble Pt or toxic Cr catalysts and suffers from coking. In this work, ferric catalyst confined in a zeolite framework was synthesized by a hydrothermal procedure. The isolated Fe in the framework formed distorted tetrahedra, which were beneficial for the selective dehydrogenation of propane and reached over 95 % propene selectivity and over 99 % total olefins selectivity. This catalyst had a silanol-free structure and was oxygen tolerant, hydrothermally stable, and coke free, with a deactivation constant of 0.01 h-1 . This study provided guidance for the synthesis of structural heteroatomic zeolite and efficient propane non-oxidative dehydrogenation over early transition metals.

Atomic-Level Imaging of Zeolite Local Structures Using Electron Ptychography.

Zeolites are among the most important heterogeneous catalysts, widely employed in separation reaction, fine chemical production, and petroleum refining. Through rational design of the frameworks, zeolites with versatile functions can be synthesized. Local imaging of zeolite structures at the atomic scale, including the basic framework atoms (Si, Al, and O) and extra-framework cations, is necessary to understand the structure-function relationship of zeolites. Herein, we implemented electron ptychography into direct imaging of local structures of two zeolites, Na-LTA and ZSM-5. Not only all the framework atoms but also extra-framework Na+ cations with only 1/4 occupation probabilities in Na-LTA were directly observed. Local structures of ZSM-5 zeolites having guest molecules among channels with different orientations were also unraveled using different reconstruction algorithms. The approach presented here provides a new way to locally image zeolites structure, and it is expected to be an essential key for further studying and tuning zeolites active sites at the atomic level.

A Six-Membered Ring Molecular Sieve Achieved by a Reconstruction Route.

Zeolite molecular sieves with at least eight-membered rings are widely applied in industrial applications, while zeolite crystals with six-membered rings are normally regarded as useless products due to the occupancy of the organic templates and/or inorganic cation in the micropores that could not be removed. Herein, we showed that a novel six-membered ring molecular sieve (ZJM-9) with fully open micropores could be achieved by a reconstruction route. The mixed gas breakthrough experiments such as CH3OH/H2O, CH4/H2O, CO2/H2O, and CO/H2O at 25 °C showed that this molecular sieve was efficient for selective dehydration. Particularly, a lower desorption temperature (95 °C) of ZJM-9 than that (250 °C) of the commercial 3A molecular sieve might offer an opportunity for saving more energy in dehydration processes.

[O-linked N-acetylglucosamine modification induced by lipopolysaccharide is involved in inflammatory signaling pathway in endothelial cells].

OBJECTIVE: To explore whether the lipopolysaccharide (LPS)-induced modification of O-linked N-acetylglucosamine (O-GlcNAc) is involved in the inflammatory signaling pathway of endothelial cells. METHODS: Human umbilical vein endothelial cells (HUVEC) were cultured in vitro, and cells in logarithmic growth phase were used for experiments. Cells were divided into blank control group, LPS group (2 000 mg/L LPS), O-GlcNAc transferase (OGT) overexpression (OGT-OE)+LPS group (plasmid transfection OGT+2 000 mg/L LPS), protein kinase C (PKC) inhibitor+LPS group (10 µmol/L Go 6983+2 000 mg/L LPS), RhoA inhibitor+LPS group (40 µmol/L Rhoin hydrochloride+2 000 mg/L LPS), phosphatidylinositol-3-kinase (PI3K) inhibitor+LPS group (1 µmol/L SL-2052+2 000 mg/L LPS), serine/threonine kinase (Akt) inhibitor+LPS group (10 µmol/L PP2+2 000 mg/L LPS) and small interfering RNA (siRNA) treated Akt (si-AKT)+LPS group (si-Akt+2 000 mg/L LPS). After 24 hours of LPS treatment, real-time fluorescence quantitative reverse transcription-polymerase chain reaction (RT-qPCR) was used to detect the transcription levels of inflammatory cytokines [interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1)]. The protein expression or phosphorylation of OGT, O-GlcNAc, Akt, extracellular signal-regulated kinase (ERK), p38 mitogen-activated protein kinase (p38MAPK), nuclear factor-κB p65 (NF-κB p65), and signal transducer and activator of transcription 3 (STAT3) were determined by Western blotting. RESULTS: Compared with the blank control group, the expression of OGT and the modification of O-GlcNAc in the LPS group were decreased, while the expressions of phosphorylated ERK, p38MAPK, and STAT3 were increased, and the transcript levels of inflammatory cytokines were also significantly increased [IL-6 mRNA (2-ΔΔCt): 4.71±0.60 vs. 1.03±0.29, TNF-α mRNA (2-ΔΔCt): 1.89±0.11 vs. 1.04±0.35, ICAM-1 mRNA (2-ΔΔCt): 2.06±0.18 vs. 1.02±0.21, VCAM-1 mRNA (2-ΔΔCt): 2.94±0.57 vs. 1.01±0.17, all P < 0.05], indicating that LPS could decrease O-GlcNAc modification, activate inflammatory signaling pathways and increase inflammatory cytokines expression. Compared with the LPS group, the expressions of phosphorylated ERK, p38MAPK, NF-κB p65, and STAT3 in the endothelial cells of the OGT-OE+LPS group were decreased, and the expression of inflammatory factors were significantly decreased [IL-6 mRNA (2-ΔΔCt): 0.12±0.01 vs. 0.90±0.17, TNF-α mRNA (2-ΔΔCt): 0.31±0.01 vs. 0.91±0.14, ICAM-1 mRNA (2-ΔΔCt): 0.64±0.02 vs. 1.13±0.16, VCAM-1 mRNA (2-ΔΔCt): 0.11±0.01 vs. 0.93±0.11, all P < 0.05], indicating that the increase of OGT level could inhibit the partial activation of the endothelial inflammatory signal pathway under the LPS stimulation. Compared with the blank control group, the phosphorylation level of Akt in the LPS group was increased. Compared with the LPS group, both OGT expression and O-GlcNAc modification were down-regulated after pretreatment of PKC inhibitor, RhoA inhibitor, PI3K inhibitor, or Akt inhibitor. Compared with the LPS group, the transcript levels of IL-6, TNF-α and ICAM-1 in the PP2+LPS group were significantly decreased [IL-6 mRNA (2-ΔΔCt): 1.46±0.16 vs. 3.55±0.87, TNF-α mRNA (2-ΔΔCt): 0.98±0.14 vs. 1.76±0.10, ICAM-1 mRNA (2-ΔΔCt): 1.39±0.24 vs. 2.04±0.13, all P < 0.05], but there was no significant change in VCAM-1. Compared with the LPS group, the expression of OGT and O-GlcNAc modification in the si-Akt+LPS group were decreased, while the transcript levels of inflammatory cytokines were also significantly decreased [IL-6 mRNA (2-ΔΔCt): 0.75±0.03 vs. 0.99±0.09, TNF-α mRNA (2-ΔΔCt): 0.69±0.01 vs. 1.10±0.08, ICAM-1 mRNA (2-ΔΔCt): 0.76±0.01 vs. 0.99±0.02, VCAM-1 mRNA (2-ΔΔCt): 0.93±0.08 vs. 1.20±0.21, all P < 0.05], indicating that Akt participated in the action process of LPS on OGT and affected the inflammatory factor expression. CONCLUSIONS: The decreased level of O-GlcNAc modification in endothelial cells stimulated with LPS promotes partial activation of inflammatory signaling pathways, mainly involving ERK, p38MAPK, and STAT3, and affects the expression of inflammatory factors. AKT may be involved in the effect of LPS on the inhibition of O-GlcNAc modification.

Cobalt-Promoted Noble-Metal Catalysts for Efficient Hydrogen Generation from Ammonia Borane Hydrolysis.

Ammonia borane (AB) has been regarded as a promising material for chemical hydrogen storage. However, the development of efficient, cost-effective, and stable catalysts for H2 generation from AB hydrolysis remains a bottleneck for realizing its practical application. Herein, a step-by-step reduction strategy has been developed to synthesize a series of bimetallic species with small sizes and high dispersions onto various metal oxide supports. Superior to other non-noble metal species, the introduction of Co species can remarkably and universally promote the catalytic activity of various noble metals (e.g., Pt, Rh, Ru, and Pd) in AB hydrolysis reactions. The optimized Pt0.1%Co3%/TiO2 catalyst exhibits a superhigh H2 generation rate from AB hydrolysis, showing a turnover frequency (TOF) value of 2250 molH2 molPt-1 min-1 at 298 K. Such a TOF value is about 10 and 15 times higher than that of the monometal Pt/TiO2 and commercial Pt/C catalysts, respectively. The density functional theory (DFT) calculation reveals that the synergy between Pt and CoO species can remarkably promote the chemisorption and dissociation of water molecules, accelerating the H2 evolution from AB hydrolysis. Significantly, the representative Pt0.25%Co3%/TiO2 catalyst exhibits excellent stability, achieving a record-high turnover number of up to 215,236 at room temperature. The excellent catalytic performance, superior stability, and low cost of the designed catalysts create new prospects for their practical application in chemical hydrogen storage.

Superconductivity from buckled-honeycomb-vacancy ordering.

Vacancies are prevalent and versatile in solid-state physics and materials science. The role of vacancies in strongly correlated materials, however, remains uncultivated until now. Here, we report the discovery of an unprecedented vacancy state forming an extended buckled-honeycomb-vacancy (BHV) ordering in Ir16Sb18. Superconductivity emerges by suppressing the BHV ordering through squeezing of extra Ir atoms into the vacancies or isovalent Rh substitution. The phase diagram on vacancy ordering reveals the superconductivity competes with the BHV ordering. Further theoretical calculations suggest that this ordering originates from a synergistic effect of the vacancy formation energy and Fermi surface nesting with a wave vector of (1/3, 1/3, 0). The buckled structure breaks the crystal inversion symmetry and can mostly suppress the density of states near the Fermi level. The peculiarities of BHV ordering highlight the importance of "correlated vacancies" and may serve as a paradigm for exploring other non-trivial excitations and quantum criticality.

A Layered Cationic Aluminum Oxyhydroxide as a Highly Efficient and Selective Trap for Heavy Metal Oxyanions.

Cationic framework materials, especially pure inorganic cationic frameworks that can efficiently and selectively capture harmful heavy metal oxyanions from aqueous solution are highly desired yet scarcely reported. Herein, we report the discovery of a 2D cationic aluminum oxyhydroxide, JU-111, which sets a new benchmark for heavy metal oxyanion sorbents, especially for CrVI . Its structure was solved based on 3D electron diffraction tomography data. JU-111 shows fast sorption kinetics (ca. 20 min), high capture capacity (105.4 mg g-1 ), and broad working pH range (3-10) toward CrVI oxyanions. Unlike layered double hydroxides (LDHs), which are poorly selective in the presence of CO3 2- , JU-111 retains excellent selectivity for CrVI even under a large excess of CO3 2- . These superior features coupled with the ultra-low cost and environmentally benign nature make JU-111 a promising candidate for toxic metal oxyanion remediation as well as other potential applications.

A Cationic Oligomer as an Organic Template for Direct Synthesis of Aluminosilicate ITH Zeolite.

There are a large number of zeolites, such as ITH, that cannot be prepared in the aluminosilicate form. Now, the successful synthesis of aluminosilicate ITH zeolite using a simple cationic oligomer as an organic template is presented. Key to the success is that the cationic oligomer has a strong complexation ability with aluminum species combined with a structural directing ability for the ITH structure similar to that of the conventional organic template. The aluminosilicate ITH zeolite has very high crystallinity, nanosheet-like crystal morphology, large surface area, fully four-coordinated Al species, and abundant acidic sites. Methanol-to-propylene (MTP) tests reveal that the Al-ITH zeolite shows much higher selectivity for propylene and longer lifetime than commercial ZSM-5. FCC tests show that Al-ITH zeolite is a good candidate as a shape-selective FCC additive for enhancing propylene and butylene selectivity.

Atomic-level handedness determination of chiral crystals using aberration-corrected scanning transmission electron microscopy.

Handedness or chirality determination is a challenging and important topic in various fields including chemistry and biology, as two enantiomers have the same composition and mirror symmetry related structures, but might show totally different activities and properties in enantioselective separations, catalysis and so on. However, current methods are unable to reveal the handedness locally of a nanocrystal at the atomic-level in real-space imaging due to the well-known fact that chiral information is lost in a two-dimensional projection. Herein, we present a method for handedness determination of chiral crystals by atomic-resolution imaging using Cs-corrected scanning transmission electron microscopy. In particular, we demonstrate that enantiomorphic structures can be distinguished through chirality-dependent features in two-dimensional projections by comparing a tilt-series of high-resolution images along different zone axes. The method has been successfully applied to certify the specific enantiomorphic forms of tellurium, tantalum silicide and quartz crystals, and it has the potential to open up new possibilities for rational synthesis and characterization of chiral crystals.

Enhanced production of aromatics from propane with a temperature-shifting two-stage fluidized bed reactor.

A temperature-shifting two-stage fluidized bed reactor technology was used to convert propane and its intermediate products into aromatics. The first stage served for the aromatization of propane with a Ga/ZSM-5 catalyst at 570 °C. The second stage served for the alkylation of the intermediates of olefins at 300 °C. The increased yield of aromatics was attributed to the effective transformation of C2-C3 olefins as well as due to the suppression of the hydrogen transfer effect of the olefins.

Factors affecting the efficacy and safety of aminophylline in treatment of apnea of prematurity in neonatal intensive care unit.

BACKGROUND: The factors affecting the safety and efficacy of aminophylline use in the treatment of apnea of prematurity (AOP) in the neonatal intensive care unit (NICU) are not clear. In this study, we aimed to evaluate the potential factors affecting the efficacy and safety of aminophylline in AOP treatment at standard doses and to determine appropriate patients for this therapy. METHODS: Over a 3-year period (January 2012 to December 2014), the medical records of 206 preterm infants with apnea who were admitted to the NICU of our hospital to receive aminophylline infusions were retrospectively reviewed. These infants were subjected to routine theophylline monitoring by reversed-phase high performance liquid chromatography. The primary outcome measures were the efficacy of aminophylline treatment and adverse reactions observed upon administration. RESULTS: One-hundred and twenty-seven (61.65%) infants were considered to have undergone effective therapy and classified accordingly. Gestational age, body weight at the initiation of aminophylline, and serum theophylline concentration were identified as protective factors of therapeutic efficacy. Receiver operating characteristic (ROC) analysis indicated cutoff values of 30.36 weeks for gestational age and 1.69 kg for body weight at initiation of aminophylline administration for ensuring high efficacy of aminophylline for AOP. Fifty-three (25.73%) infants had adverse reactions. Birth weight and serum concentration of theophylline were associated with an increased risk of adverse reactions, with odds ratios of 0.167 and 1.346, respectively. The ROC curves indicated a birth weight cutoff value of 1.48 kg. CONCLUSION: Infants with apnea and gestational age >30.36 weeks, body weight at initiation of aminophylline treatment above 1.69 kg, and birth weight >1.48 kg are suitable for treatment with aminophylline. Monitoring of serum theophylline concentration should be implemented in the absence of clinical response or in case of suspected adverse reactions.

[Responses of Nicotiana tabacum morphology and photosynthetic physiology to reduced ultraviolet-B radiation].

By the method of canopy film-covering to reduce UV-B radiation, this paper studied the responses of the morphology and photosynthetic physiology of Nicotiana tabacum cultivar K326 at its physiological, technical, and physiological-technical transitional maturity stages in high-elevation tobacco-growing area of Yunnan. Three treatments were installed, i.e., reducing 75.74% (T1), 70.08% (T2), and 30.39% (T3) of natural solar UV-B radiation. Reducing UV-B radiation increased the stem height and the internode distance of K326 significantly, with the larger values in T2. Comparing with those under natural UV-B radiation condition, the leaf net photosynthetic rate (Pn), assimilation capacity (AC), water use efficiency (WUE), intrinsic water use efficiency (WUEi), photosynthetic pigments (PP) and flavonoids (FL) contents, and specific leaf mass (SLM) in T1 and T2 all decreased, with larger decrement in T2. The factors affecting the Pn in T, and T2 were stomatal and non-stomatal, and the latter was the main one. The major reason of the lower WUE in T1 and T2 was due to the increase of transpiration rate (Tr) caused by low stomatal regulation capability. In T3, the Pn, AC, WUE, WUEi, and PP increased but the FL and PP decreased to the lowest levels at physiological and transitional maturity stages, and the PP degradation rate was faster at the technical maturity stage.