Structures of apo Cas12a and its complex with crRNA and DNA reveal the dynamics of ternary complex formation and target DNA cleavage.

Cas12a is a programmable nuclease for adaptive immunity against invading nucleic acids in CRISPR-Cas systems. Here, we report the crystal structures of apo Cas12a from Lachnospiraceae bacterium MA2020 (Lb2) and the Lb2Cas12a+crRNA complex, as well as the cryo-EM structure and functional studies of the Lb2Cas12a+crRNA+DNA complex. We demonstrate that apo Lb2Cas12a assumes a unique, elongated conformation, whereas the Lb2Cas12a+crRNA binary complex exhibits a compact conformation that subsequently rearranges to a semi-open conformation in the Lb2Cas12a+crRNA+DNA ternary complex. Notably, in solution, apo Lb2Cas12a is dynamic and can exist in both elongated and compact forms. Residues from Met493 to Leu523 of the WED domain undergo major conformational changes to facilitate the required structural rearrangements. The REC lobe of Lb2Cas12a rotates 103° concomitant with rearrangement of the hinge region close to the WED and RuvC II domains to position the RNA-DNA duplex near the catalytic site. Our findings provide insight into crRNA recognition and the mechanism of target DNA cleavage.

Rearrangement of a unique Kv1.3 selectivity filter conformation upon binding of a drug.

We report two structures of the human voltage-gated potassium channel (Kv) Kv1.3 in immune cells alone (apo-Kv1.3) and bound to an immunomodulatory drug called dalazatide (dalazatide-Kv1.3). Both the apo-Kv1.3 and dalazatide-Kv1.3 structures are in an activated state based on their depolarized voltage sensor and open inner gate. In apo-Kv1.3, the aromatic residue in the signature sequence (Y447) adopts a position that diverges 11 Å from other K+ channels. The outer pore is significantly rearranged, causing widening of the selectivity filter and perturbation of ion binding within the filter. This conformation is stabilized by a network of intrasubunit hydrogen bonds. In dalazatide-Kv1.3, binding of dalazatide to the channel's outer vestibule narrows the selectivity filter, Y447 occupies a position seen in other K+ channels, and this conformation is stabilized by a network of intersubunit hydrogen bonds. These remarkable rearrangements in the selectivity filter underlie Kv1.3's transition into the drug-blocked state.

Impact of unintentional coronary angiography on outcomes of emergency surgery in acute type A aortic dissection: a retrospective study.

BACKGROUND: This study investigated the impact of coronary angiography on outcomes of emergency operation in acute type A aortic dissection (ATAAD) patients who were initially misdiagnosed as an acute coronary syndrome. METHODS: From October 2016 to April 2019, 129 patients underwent emergency operation for ATAAD in our institution, including 21 patients (16.3%, coronary angiography group) who received preoperative coronary angiography without knowledge of the ATAAD, and the rest 108 did not (Non-coronary angiography group). Preoperative clinical characteristics, 30-day mortality and postoperative complications were compared. Multivariable logistic regression was performed to confirm the independent prognostic factors for short-term and long-term outcomes. RESULTS: Patients undergoing coronary angiography had higher prevalence of preoperative hypotension or shock (61.9% vs 35.2%, P = 0.022), ischemic changes on electrocardiogram (66.7% vs 37.0%, P = 0.012), platelet inhibition (ADP-induced inhibition 92.0% vs 46.0%, P = 0.001), and coronary involvement (66.7% vs 30.6%, P = 0.002). 30-day mortality was 4.8% versus 9.3% (P = 0.84). Coronary angiography group had more intraoperative bleeding (1900 ml vs 1500 ml, P = 0.013) and chest-tube drainage on the first postoperative day (1040 ml vs 595 ml, P = 0.028). However, preoperative coronary angiography was not independent risk factors for 30-day mortality (OR 0.171, 95%CI 0.013-2.174, P = 0.173) and overall survival (HR 0.407; 95%CI 0.080-2.057; P = 0.277). CONCLUSION: Patients undergoing coronary angiography carried a higher risk of preoperative hemodynamic instability, myocardial ischemia, and perioperative bleeding. However, unintentional coronary angiography did not have a significant impact on short-term and long-term outcomes of emergency surgery in ATAAD.

A new highly selective fluorescent sensor based on a novel fluorophore for cyanide and its applications in bioimaging.

A novel highly active fluorescence chemical sensor (TBI) for CN- was synthesized based on triphenylamine-benzothiazole as a new fluorophore, and was used for the first time as a fluorophore for detection of CN- . Fluorescence quantum yield of the probe clearly increased when using triphenylamine-benzothiazole as the group. The probe possessed good selectivity towards CN- and had anti-interference ability over common ions. After adding CN- , the UV-visible spectrum of TBI changed clearly and underwent a dramatic colour change from red to colourless, which could be observed clearly by the naked eye. The limit of detection for CN- was calculated to be 2.62 × 10-8 M, which was well below the WHO cut-off point of 1.9 µM. The novel probe displayed fast sensing of CN- . The detection mechanism was a nucleophilic addition reaction between CN- and a carbon atom -C = N- in indole salt. The π-conjugation and intramolecular charge transfer (ICT) transition in the TBI molecule were destroyed by this addition, which resulted in a change of fluorescence before and after the addition of CN- . The mechanism was verified using theoretical calculation, 1 H NMR titration, and mass spectra. In addition, the probe showed low cytotoxicity and could be used for biological imaging in HeLa cells.

The Cardioprotective Effects of Remote Ischemic Conditioning in a Rat Model of Acute Myocardial Infarction.

BACKGROUND Cardiac remote ischemic conditioning (RIC) is a noninvasive cardioprotective method in ischemia-reperfusion injury and acute myocardial infarction (AMI). The aims of this study were to investigate the effects of RIC in a rat model of AMI. MATERIAL AND METHODS Adult male Sprague-Dawley rats included the AMI group that underwent ligation of the left anterior descending (LAD) coronary artery (n=24), the RIC group that consisted the AMI rat model treated with RIC once daily in the left hind limb until days 1, 7 and 14 (n=24), and the sham group (n=24). Myocardial infarct size was measured by routine histology with triphenyltetrazolium chloride (TTC) and Masson's trichrome histochemical staining for myocardial necrosis and fibrosis, respectively. Serum levels of Bcl-2, Bax, caspase-3, and inducible nitric oxide synthase (iNOS) were measured by enzyme-linked immunosorbent assay (ELISA). The apoptosis index was detected using the TUNEL assay. Spectrophotometry of the myocardium was used to identify mitochondrial complexes and myocardial ATP. RESULTS The RIC group showed improved cardiac hemodynamics, reduced the size of the myocardial infarction, upregulated expression of Bcl-2, and down-regulation of the levels of Bax, caspase-3, and iNOS, and reduced cardiac myocyte apoptosis and inhibited the opening of the mitochondrial permeability transition pore (MPTP). CONCLUSIONS In a rat model of AMI, RIC improved the hemodynamic index, reduce the levels of apoptosis and myocardial injury, and improved mitochondrial function.

Therapeutic effects of a taurine-magnesium coordination compound on experimental models of type 2 short QT syndrome.

Short QT syndrome (SQTS) is a genetic arrhythmogenic disease that can cause malignant arrhythmia and sudden cardiac death. The current therapies for SQTS have application restrictions. We previously found that Mg· (NH2CH2CH2SO3)2· H2O, a taurine-magnesium coordination compound (TMCC) exerted anti-arrhythmic effects with low toxicity. In this study we established 3 different models to assess the potential anti-arrhythmic effects of TMCC on type 2 short QT syndrome (SQT2). In Langendorff guinea pig-perfused hearts, perfusion of pinacidil (20 µmol/L) significantly shortened the QT interval and QTpeak and increased rTp-Te (P<0.05 vs control). Subsequently, perfusion of TMCC (1-4 mmol/L) dose-dependently increased the QT interval and QTpeak (P<0.01 vs pinacidil). TMCC perfusion also reversed the rTp-Te value to the normal range. In guinea pig ventricular myocytes, perfusion of trapidil (1 mmol/L) significantly shortened the action potential duration at 50% (APD50) and 90% repolarization (APD90), which was significantly reversed by TMCC (0.01-1 mmol/L, P<0.05 vs trapidil). In HEK293 cells that stably expressed the outward delayed rectifier potassium channels (IKs), perfusion of TMCC (0.01-1 mmol/L) dose-dependently inhibited the IKs current with an IC50 value of 201.1 µmol/L. The present study provides evidence that TMCC can extend the repolarization period and inhibit the repolarizing current, IKs, thereby representing a therapeutic candidate for ventricular arrhythmia in SQT2.

Effects of non-invasive remote ischemic conditioning on rehabilitation after myocardial infarction.

Recent studies have demonstrated that remote ischemic conditioning (RIC) creates cardioprotection against ischemia/reperfusion injury and myocardial infarction (MI); however, the effects of non-invasive remote ischemic conditioning (nRIC) on prognosis and rehabilitation after MI (post-MI) remain unknown. We successfully established MI models involving healthy adult male Sprague-Dawley rats. The nRIC group repeatedly underwent 5 min of ischemia and 5 min of reperfusion in the left hind limb for three cycles every other day until weeks 4, 6, and 8 after MI. nRIC improved cardiac hemodynamic function and mitochondrial respiratory function through increasing myocardial levels of mitochondrial respiratory chain complexes I, II, III, IV, and adenosine triphosphate (ATP) and decreasing the activity of nitric oxide synthase (NOS). nRIC could inhibit cardiomyocytes apoptosis and reduce myocardium injury through raising the expression of Bcl-2 and reduced the content of creatine kinase-MB, cardiac troponin I and Bax. The results indicated that long-term nRIC could accelerate recovery and improve prognosis and rehabilitation in post-MI rats.

Domino Reactions Containing Different Types of Heck Reactions for Selective 3,3- and 1,3-Diarylations of Propenol with Aryl Halides by Triple Catalysis.

A new domino Heck-isomerization/Saegusa/Heck reaction of propenol with aryl iodides has been developed for the synthesis of 3,3-diaryl propenals by triple transition-metal catalysis. Moreover, we also developed the domino Heck-isomerization/Heck-type reaction of propenol with aryl iodides for the synthesis of 1,3-diaryl propanones by double transition-metal catalysis and the mediation of secondary amine or triple transition metal catalysis and aminocatalysis.

A dehydrogenative cross-coupling reaction between aromatic aldehydes or ketones and dialkyl H-phosphonates for formyl or acylphenylphosphonates.

A novel DCC reaction between aromatic aldehydes or ketones and H-phosphonates has been developed for the synthesis of p-formyl or p-acylphenylphosphonates. The synthetic method has excellent para regioselectivities, good yields, and broad substrate scopes and is more benign to the environment. The DCC reaction also tolerates many functional groups, and results in a series of new p-formyl and p-acylphenylphosphonates, which should be important building blocks for the synthesis of versatile arylphosphonate derivatives.

Biological evaluation of a cytotoxic 2-substituted benzimidazole copper(II) complex: DNA damage, antiproliferation and apoptotic induction activity in human cervical cancer cells.

Exploring novel chemotherapeutic agents is a great challenge in cancer medicine. To that end, 2-substituted benzimidazole copper(II) complex, [Cu(BMA)Cl2]·(CH3OH) (1) [BMA = N,N'-bis(benzimidazol-2-yl-methyl)amine], was synthesized and its cytotoxicity was characterized. The interaction between complex 1 and calf thymus DNA was detected by spectroscopy methods. The binding constant (K b = 1.24 × 10(4 )M(-1)) and the apparent binding constant (K app = 6.67 × 10(6 )M(-1)) of 1 indicated its moderate DNA affinity. Complex 1 induced single strand breaks of pUC19 plasmid DNA in the presence of H2O2 through an oxidative pathway. Cytotoxicity studies proved that complex 1 could inhibit the proliferation of human cervical carcinoma cell line HeLa in both time- and dose-dependent manners. The results of nuclei staining by Hoechst 33342 and alkaline single-cell gel electrophoresis proved that complex 1 caused cellular DNA damage in HeLa cells. Furthermore, treatment of HeLa cells with 1 resulted in S-phase arrest, loss of mitochondrial potential, and up-regulation of caspase-3 and -9 in HeLa cells, suggesting that complex 1 was capable of inducing apoptosis in cancer cells through the intrinsic mitochondrial pathway.

New insights into the magnetism and magnetic structure of LuCrO3 perovskite.

A polycrystalline sample LuCrO3 has been characterized by neutron powder diffraction (NPD) and magnetization measurements. Its crystal structure has been Rietveld refined from NPD data in space group Pnma; this perovskite contains strongly tilted CrO6 octahedra with extremely bent Cr-O-Cr superexchange angles of ∼142°. The NPD data show that below Néel temperature (TN ≃ 131 K), the magnetic structure can be defined as an A-type antiferromagnetic arrangement of Cr3+ magnetic moments, aligned along the b axis, with a canting along the c axis. A noticeable magnetostrictive effect is observed in the unit-cell parameters and volume upon cooling down across TN. The AC magnetic susceptibility indicates the onset of magnetic ordering below 112.6 K; the magnetization isotherms below TN show a nonlinear behaviour that is associated with the described canting of the Cr3+ magnetic moments. From the Curie-Weiss law, the effective moment of the Cr3+ sublattice is found to be µeff = 3.55 µB (calculated 3.7 µB) while the ΘCW parameter yields a value of -155 K, indicating antiferromagnetic interactions. There is a conspicuous increase of TN upon the application of external pressure, which must be due to shortening of the Cr-O bond length under compression that increases the orbital overlap integral.

[Study on the constituents of essential oil of Shunaoxin dropping pills by GC-MS].

OBJECTIVE: To study the constituents of essential oil from Shunaoxin dropping pills by GC-MS. METHODS: The essential oil from Shunaoxin dropping pills were extracted by absolute alcohol and analyzed by GC-MS. RESULTS: 15 components from the essential oil of Shunaoxin dropping pills were identified. CONCLUSION: The main components in the essential oil of Shunaoxin dropping pills are lactones such as Z-ligustilide, senkyunolide A,3-butylphthalide and 3-butylidenephthalide, other components are organic acids such as ethyl linoleate, 9,12-octadecadienoic acid and ethyl palmitate.

A study of the proteomic expression in patients with complicated parapneumonic pleural effusion.

Introduction: The present study aimed to investigate the differences in the proteomic expression between uncomplicated parapneumonic pleural effusion (UPPE) and complicated parapneumonic pleural effusion (CPPE). Material and methods: There were 10 patients with UPPE and 10 patients with CPPE. These patients were combined due to the complication of pleural effusion and further divided into group A and group B. An LC-MS analysis was conducted with the extraction of high-abundance proteins, and proteins with 1.5-fold or higher difference multiples were identified as differential proteins. Then, gene ontology (GO) and KEGG analyses were conducted on the differential proteins between the groups. Results: Compared with the UPPE group, there were 38 upregulated proteins and 29 downregulated proteins in the CPPE group. The GO analysis revealed that the CPPE group had enhanced expressions in monosaccharide biosynthesis, glucose catabolism, fructose-6-phosphate glycolysis, glucose-6-phosphate glycolysis, and NADH regeneration as well as reduced expressions in fibrinogen complexes, protein polymerization, and coagulation. Moreover, the KEGG analysis showed that the CPPE group had enhanced expressions in amino acid synthesis, the HIF-1 signalling pathway, and glycolysis/glycoisogenesis and decreased expressions in platelet activation and complement activation. Conclusions: In pleural effusion in patients with CPPE, there are enhanced expressions of proteins concerning glucose and amino acid metabolism, NADH regeneration, and HIF-1 signalling pathways together with decreased expressions of proteins concerning protein polymerization, blood coagulation, platelet activation, and complement activation.

Noninvasive delayed limb ischemic preconditioning in rats increases antioxidant activities in cerebral tissue during severe ischemia-reperfusion injury.

BACKGROUND: To study the protection offered by noninvasive delayed limb ischemic preconditioning (NDLIP) against cerebral ischemia reperfusion (I/R) injury in rats. MATERIALS AND METHODS: Healthy male Wistar rats were randomly divided into four groups. The delayed protection offered by NDLIP was estimated in light of changes in the neural behavior marker and cerebral tissue antioxidative ability. Neurological functions were studied by observing neural behavior. Total superoxide dismutase (T-SOD), manganese-superoxide dismutase (Mn-SOD), glutathione peroxidase (GSH-PX), and xanthine oxidase (XOD) activity in cerebral tissue and malonaldehyde (MDA) content were detected using a spectrophotometer. Mn-SOD mRNA was measured by the reverse transcription polymerase chain reaction method. RESULTS: Cerebral infarct size was diminished in the early cerebral ischemia preconditioning (ECIP)+I/R and NDLIP+I/R groups compared with the I/R group (P < 0.05). The cortical and hippocampal antioxidant enzyme activity and Mn-SOD expression were increased in the ECIP+I/R and NDLIP+I/R groups. In contrast, the cortical and hippocampal XOD activity and MDA content decreased in the ECIP+I/R and NDLIP+I/R groups. CONCLUSIONS: NDLIP decreased cerebral infarct size, increased cerebral antioxidative ability after I/R injury, and decreased peroxidative damage. The antioxidative protection offered by NDLIP was as effective as that offered by ECIP.

Visual analysis of global research output of lymphedema based on bibliometrics.

Background: Globally, several generations of doctors in the field of lymphedema have created numerous publications. To date, no bibliometric analysis has been performed specifically on these publications. For the further promotion of research on lymphedema and to align with the international research frontiers, it is essential to understand the current state of Lymphedema research output. Objective: This study aims to statistically and visually analyze the characteristics of publications output, distribution of contributions and development process of lymphedema, enriching the knowledge base of Lymphedema, and then seek potential research topics and collaborators. Methods: Based on the Web of Science core collection database, we firstly analyzed the quantity and quality of publications in the field of lymphedema, secondly profiled the publishing groups in terms of country, institution, author's publication and cooperation network, and finally sorted out and summarized the hot topics of research. Results: A total of 8569 papers were retrieved from 1900-2021. The top4 journals with the most publications were LYMPHOLOGY, LYMPHATIC RESEARCH AND BIOLOGY, PLASTIC AND RECONSTRUCTIVE SURGERY and ANNALS OF SURGICAL ONCOLOGY. The top 4 countries with the most publications were USA, Japan, UK, and China. The United States dominates the total number of publications and the international cooperation network. The most productive research institution is Harvard University, and the research institution with the most collaborating institutions is Memorial Sloan Kettering Cancer Center. Mortimer, Peter S contributes the most research in this field. The research achievements of Japanese scholars in this field are of great significance. The top 5 ranked keywords are "Breast Cancer", "Health-Related Quality Of Life", "Lymphscintigraphy", "Lymphovenous Anastomosis", and "Lymphangiogenesis". Conclusion: More and more scholars are devoted to the research of cancer-related Lymphedema. It is foreseeable that breast cancer-related lymphedema and lymphangiogenesis will remain a focus of future research. Advances in Lymphatic vessel imaging and the development of lymphatic microsurgery will further play a role in the clinical workup of lymphedema. Meanwhile, This study can help researchers identify potential collaborators and partner institutions and contribute to further research.

Acetylated anthraquinone glycosides from Cassia obtusifolia.

Three new acetylated anthraquinone glycosides (1-3) were isolated from the seed of Cassia obtusifolia, together with one parent anthraquinone glycoside (1a). Their structures were determined on the basis of spectroscopic methods and physicochemical properties as obtusifoline-2-O-ß-d-2, 6-di-O-acetylglucopyranoside (1), obtusifoline-2-O-ß-d-glucopyranoside (1a), obtusifoline-2-O-ß-d-3, 6-di-O-acetylglucopyranoside (2), and obtusifoline-2-O-ß-d-4, 6-di-O-acetylglucopyranoside (3).

2-Phenyl-imidazolium hemi(benzene-1,3-dicarboxyl-ate) monohydrate.

The asymmetric unit of the title compound, C(9)H(9)N(2) (+)·0.5C(8)H(4)O(4) (-)·H(2)O, contains one 2-phenyl-imidazolium cation, half a benzene-1,3-dicarboxyl-ate anion and one water mol-ecule. In the crystal, components are connected by N-H⋯O and O-H⋯O hydrogen-bonding inter-actions into a three-dimensional network.

Engineering an Indium Selenide van der Waals Interface for Multilevel Charge Storage.

As the continuous miniaturization of floating-gate transistors approaches a physical limit, new innovations in device architectures, working principles, and device materials are in high demand. This study demonstrated a nonvolatile memory structure with multilevel data storage that features a van der Waals gate architecture made up of a partially oxidized surface layer/indium selenide (InSe) van der Waals interface. The key functionality of this proof-of-concept device is provided through the generation of charge-trapping sites via an indirect oxygen plasma treatment on the InSe surface layer. In contrast to floating-gate nonvolatile memory, these sites have the ability to retain charge without the help of a gate dielectric. Together with the layered structure, the surface layer with charge-trapping sites facilitates continual electrostatic doping in the underlying InSe layers. The van der Waals gating effect is further supported by trapped charge-induced core-level energy shifts and relative work function variations obtained from operando scanning X-ray photoelectron spectroscopy and Kelvin probe microscopy, respectively. On modulating the amount of electric field-induced trapped electrons by the electrostatic gate potential, eight distinct storage states remained over 3000 s. Moreover, the device exhibits a high current switching ratio of 106 within 11 cycles. The demonstrated characteristics suggest that the engineering of an InSe interface has potential applications for nonvolatile memory.

Molecular characteristics of H9N2 influenza viruses isolated from farmed raccoon dogs and arctic foxes in China.

In this study, eight H9N2 IAVs were isolated from infected diseased, farmed raccoon dogs and arctic foxes. Eight genes shared 98.6%-100% identity among the isolates possessing a PSRSSR/GL motif at the HA cleavage site, which is same as the motif of G1 and Y280 lineages of H9N2 IAVs. The phylogenetic analysis showed that the HA genes of the eight isolates clustered with Y280-like viruses, whereas the NA genes belonged to F/98-like sublineage. Interestingly, the NS, NP, PB2 and PA genes of the isolates were closely related to H7N9 IAVs. This is the first evidence for isolation of H9N2 IAVs from raccoon dogs and arctic foxes. Raccoon dogs and arctic foxes potentially serve as an intermediate host for influenza viruses with pandemic potential toward other animals due to co-expression of both SA α-2,6-Gal and SA α-2,3-Gal receptors in a wide range of their tissues.

[Hydrochemical Characteristics and Origin of Groundwater in the Central Guohe River Basin].

Groundwater is an important water source in the central Guohe River basin but pollution and water quality deterioration present a significant challenge. Here, 80 groups of groundwater samples were collected between June and September 2019 including 61 groups of shallow groundwater samples, 9 groups of middle groundwater samples, and 10 groups of deep groundwater samples. The hydrochemical characteristics and formation mechanisms of groundwater at these different depths were analyzed using statiatical techniques, Piper triangular diagrams, Gibbs figures, and ion ratios. The following results were noted:① Groundwater is weakly alkaline overall, and the dominant anion and cation at different depths were HCO3- and Na+. The shallow and deep groundwater mainly consist of fresh water while the middle groundwater is mainly brackish water. The hydrochemical typology of the shallow groundwater was mainly HCO3-Ca·Mg and HCO3-Na·Mg. HCO3·SO4·Cl-Na was found to be the dominant hydrochemical typology in the middle and deep groundwater. ② The chemical composition of the groundwater shows notable vertical variations. With depth, the mean mass concentrations of TDS, Na+, Mg2+, Cl-, SO42-, and HCO3- first increase and then decreasing, while the mean mass concentration of Ca2+ gradually decreases. These vertical differences are closely related to the sedimentary environment of the aquifer and the intensity of water-rock interaction. ③ The formation of groundwater hydrochemical characteristics is influenced by water-rock interactions, cation exchange, and human activities, with water-rock interaction dominated by sodium silicate dissolution. Human activities generally have the greatest impact on the shallow groundwater. ④ The water quality of the deep groundwater is notably better than that of the shallow and middle groundwater. However, excessive exploitation of the deep groundwater resource has led to the formation of a regional groundwater funnel, enhancing the difference in middle and deep groundwater levels. To reduce the risk of ground subsidence and the contamination of the deep water with middle brackish water, deep groundwater exploitation wells should be carefully positioned and regulated.