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1.
Clin Cardiol ; 44(11): 1575-1585, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34651329

RESUMO

BACKGROUND: Dyslipidemia International Study II (DYSIS II)-China was conducted to determine the low-density lipoprotein cholesterol (LDL-C) goal (<1.8 mmol/L) attainment rate in patients with post-acute coronary syndrome (ACS). HYPOTHESIS: Compliance with treatment guideline recommendations improves the LDL-C goal attainment rate in post-ACS patients. METHODS: This multicenter prospective observational study conducted at 28 tertiary hospitals determined the LDL-C goal attainment rates at admission and 6-month follow-up in patients on lipid-lowering treatment (LLT) for ≥3 months and those not on LLT (LLT-naive or off LLT for ≥3 months) at admission. Predictors of goal attainment at 6 months were identified using multivariate logistic regression. RESULTS: The LDL-C goal attainment rate at admission in 1102/1103 enrolled patients was 17.1%; it was 41.2% among 752 patients with available lipid results at 6 months. The distance to goal was 0.7 mmol/L at 6 months. Statin monotherapy was the most prescribed LLT. Only 7.7% of patients were receiving statin + ezetimibe and 8.4% of patients were receiving an atorvastatin-equivalent dose of ≥40 mg/day at 6 months. Being male (odds ratio [OR] 1.7, 95% confidence interval [CI] 1.1-2.6) and undergoing percutaneous coronary intervention during index hospitalization (OR 1.5, 95% CI 1.1 to 2.1) were the independent predictors for LDL-C goal attainment. CONCLUSIONS: This real-world DYSIS II study in China reports a low LDL-C goal attainment rate in post-ACS patients even after 6 months of LLT. Lack of intensification of statin therapy and underutilization of combinations suggest gaps between real-world treatment practices and guideline recommendations.


Assuntos
Síndrome Coronariana Aguda , Dislipidemias , Inibidores de Hidroximetilglutaril-CoA Redutases , Síndrome Coronariana Aguda/diagnóstico , Síndrome Coronariana Aguda/tratamento farmacológico , China/epidemiologia , Dislipidemias/diagnóstico , Dislipidemias/tratamento farmacológico , Dislipidemias/epidemiologia , Objetivos , Humanos , Inibidores de Hidroximetilglutaril-CoA Redutases/uso terapêutico , Lipídeos , Masculino , Resultado do Tratamento
2.
Inorg Chem ; 60(20): 15759-15767, 2021 Oct 18.
Artigo em Inglês | MEDLINE | ID: mdl-34606253

RESUMO

The crown-shaped organotriphosphonate-modified 36-molybdenum cluster (NH4)18Na7H11[Zn(H2O)TeMo6O21{N(CH2PO3)3}]6·23H2O (1) has been synthesized, which is the largest zinc-containing organophosphonate-based polyoxometalate to date. Compound 1 was prepared in buffer solution (pH 5.5) with heptamolybdate and amino trimethylene phosphonic acid (ATMP) as the organic ligand. The polyanion constructed from a hexmeric assembly of [Zn(H2O){TeMo6O21}{N(CH2PO3)3}]6- subunits has been fully investigated by a few characterization methods. In this work, we discovered that 1 exhibited reversible photochromism and it changed from white to reddish brown upon UV irradiation. In addition, compound 1, as a catalyst, can oxidize sulfides to sulfoxides, showing a high yield/conversion and a good selectivity.

3.
Eur J Pain ; 2021 Oct 26.
Artigo em Inglês | MEDLINE | ID: mdl-34698423

RESUMO

OBJECTIVE: This study was designed to evaluate the efficacy of analgesia and incidence of postoperative nausea and vomiting (PONV) of several widely used clinical treatments for postoperative analgesia following abdominal surgery through network meta-analysis (NMA) based on published randomized controlled trials (RCTs). METHODS: This NMA was registered on PROSPERO as CRD 42020169606. Primary outcomes were pain scores (visual analog scale) and accumulative opioid consumption, and secondary outcomes assessed the incidence of PONV at 24 h after surgery. RESULTS: A total of 215 RCTs and 15,114 patients were identified in this NMA. In comparison with placebo, use of a preoperative paravertebral block (mean: -12.63, 95% CI: -21.12 to -4.13), continuous wound infiltration (mean: -9.68, 95%CI: -13.15 to -6.22) and postoperative wound infiltration (mean: -6.34, 95%CI: -10.59 to -2.08) had significantly lower pain scores, less opioid consumption (mean: -2.00, 95%CI: -3.52 to -0.48; mean: -1.34, 95%CI: -1.87 to -0.81; mean: -1.41, 95%CI: -2.07 to -0.74, respectively) and lower incidence of PONV (OR: 0.30, 95%CI: 0.13 to 0.67; OR: 0.49, 95%CI: 0.24 to 0.98; OR: 0.55, 95%CI: 0.34 to 0.89, respectively). CONCLUSIONS: The findings from our work provide evidence that preoperative paravertebral block was superior to continuous or postoperative wound infiltration to provide postoperative analgesia, nausea and vomiting after abdominal surgery.

4.
Chem Commun (Camb) ; 57(80): 10415-10418, 2021 Oct 07.
Artigo em Inglês | MEDLINE | ID: mdl-34546227

RESUMO

Ultrafine ternary carbide Co6W6C@C nanoparticles (NPs) were successfully synthesized and these NPs exhibited high catalytic activities for the hydrazine oxidation reaction (HzOR) under alkaline conditions. In a practical O2-hydrazine fuel cell test, its peak power density reached 203 mW cm-2, a value superior to that of the state-of-the-art commercial Pt/C catalyst.


Assuntos
Fontes de Energia Elétrica , Hidrazinas/química , Nanopartículas Metálicas/química , Carbono/química , Catálise , Cobalto/química , Eletrodos , Oxirredução , Oxigênio/química , Compostos de Tungstênio/química
5.
Front Bioeng Biotechnol ; 9: 734810, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34532316

RESUMO

Since obesity impairs wound closure and adipose-derived exosomes (ADEs) regulate wound healing in clinical applications, we hypothesized that ADEs may inhibit adipogenesis of adipose-derived stem cells (ADSCs) to reduce the adverse effects of obesity on wound healing. Hedgehog (Hh) signaling has been previously shown to inhibit adipogenesis in ADSCs. The present study aimed to determine the role of ADEs in the adipogenesis of ADSCs and the Hh signaling pathway. ADSCs collected from human adipose tissues were co-cultured with ADEs and treated with an adipogenic inducer. qRT-PCR showed that ADEs could inhibit adipogenic differentiation of ADSCs and activate Hh signaling. The differences in the mRNA expression profiles of genes related to Hh signaling between the groups that were exposed to either high fat or low fat indicated that increased Hh signaling activation is necessary but not sufficient to inhibit adipogenic differentiation in the ADSC differentiation process. The Hh signaling pathway can be activated effectively by ADEs, especially during high-fat exposure after treatment with ADEs. Oil Red O staining of adipocytes suggested that ADEs inhibited not only adipogenic differentiation, but also lipogenesis in ADSCs. Overall, targeted activation of Hh signaling by ADEs reduced lipid accumulation in ADSCs and may be explored for clinical applications.

6.
Inorg Chem ; 60(19): 14872-14879, 2021 Oct 04.
Artigo em Inglês | MEDLINE | ID: mdl-34533941

RESUMO

A novel organodiphosphonate-based telluromolybdate cluster, (NH4)6Na3H13[TeMo10O37(CoMo2O6L)4]·11H2O [1; L = (O3P)2C(O)(CH2)3NH2], has been successfully synthesized by a simple one-pot aqueous reaction. Intriguingly, the [TeMo10O37]10- subunit with tetrahedral geometry of TeO4 is observed in the organophosphonate-functionalized polyoxometalates for the first time. Compound 1 was prepared in a buffer solution (pH = 5.5) with alendronic acid (Ale) and (NH4)6Mo7O24·4H2O as raw materials. The polyanion [TeMo10O37(CoMo2O6L)4]22- was constructed from four {Mo2O6L} subunits encapsulating an interesting Te-Mo heterometal subunit [TeMo10O37]10- through four CoO6 octahedra and has been fully characterized by routine techniques. In addition, compound 1, as a heterogeneous catalyst, shows good conversion (92%) and high selectivity (99%) for Knoevenagel condensation reaction.

7.
Chem Commun (Camb) ; 57(79): 10250-10253, 2021 Oct 05.
Artigo em Inglês | MEDLINE | ID: mdl-34528652

RESUMO

The first example of Rh-substituted organic-inorganic hybrid arsenotungstate [H2N(CH3)2]8{[Na(H2O)4]NaAs2W22(CH3COO)2O76 Rh2(N(CH3)2)2}·H2O (1) synthesised in an aqueous solution by the conventional method is reported. Two [Rh(N(CH3)2)]3+ fragments are imbedded into the vacancy of the [NaAs2W22(CH3COO)2O76]15- unit by Rh-As bonds [2.439(1) Å], which are observed in POM chemistry for the first time.

8.
Fertil Steril ; 2021 Sep 18.
Artigo em Inglês | MEDLINE | ID: mdl-34548165

RESUMO

OBJECTIVE: To compare the effect of preoperative intravenous (IV) acetaminophen versus oral (PO) acetaminophen or placebo on postoperative pain scores and the time to discharge in women undergoing oocyte retrieval. DESIGN: Randomized, double-blind, placebo-controlled trial. SETTING: Single academic fertility center. PATIENT(S): Women aged 18-43 years undergoing oocyte retrieval. INTERVENTION(S): Randomization to preoperative 1,000 mg IV acetaminophen and PO placebo (group A), IV placebo and 1,000 mg PO acetaminophen (group B), or IV and PO placebo (group C) MAIN OUTCOME MEASURE(S): Difference in patient-reported postoperative visual analog scale pain scores from baseline and the time to discharge. RESULT(S): Of the 159 women who completed the study, there were no differences in the mean postoperative pain score differences or the time to discharge. Although not statistically significant, the mean postoperative opioid dose requirement in group A was lower than that in groups B and C (0.24 vs. 0.59 vs. 0.58 mg IV morphine equivalents, respectively) due to fewer women in group A requiring rescue pain medication (8% vs. 19% vs. 15%, respectively). Group A also reported less constipation when compared with groups B and C (19% vs. 33% vs. 40%, respectively). The rates of postoperative nausea were similar, and there were no differences in embryology or early pregnancy outcomes between the study groups. CONCLUSION(S): Preoperative IV acetaminophen for women undergoing oocyte retrieval did not reduce postoperative pain scores or shorten the time to discharge when compared with PO acetaminophen or placebo and, thus, cannot currently be recommended routinely in this patient population. CLINICAL TRIAL REGISTRATION NUMBER: NCT03073980.

9.
Dalton Trans ; 50(36): 12664-12673, 2021 Sep 21.
Artigo em Inglês | MEDLINE | ID: mdl-34545885

RESUMO

A novel ruthenium-containing polyoxometalate-based organic-inorganic hybrid, K4Na9H7.4[(AsW9O33)4(WO2)4{Ru3.2(C3H3N2)2}]·42H2O (1), was successfully synthesized by a one-step hydrothermal method under acidic conditions, which applied a self-assembly strategy between inorganic polyoxometalate based on trivacant [B-α-AsW9O33]9- {AsW9} fragments and an organic ligand, imidazole (C3H4N2). Compound 1 was further characterized by single-crystal X-ray diffraction, PXRD, IR spectroscopy, UV-Vis spectroscopy, ESI-MS, elemental analysis and TGA. Single-crystal X-ray diffraction data reveal that the polyanion consists of four trivacant Keggin-type polyanion {AsW9} building blocks bridged by four {WO6} units, leading to a crown-shaped tetrameric structure [(AsW9O33)4(WO2)4{Ru3.2(C3H3N2)2}]20.4-. The ESI-MS result reveals that the polyanion unit has excellent structural integrity in water. Moreover, the catalysis study of 1 was also further investigated, and the experimental results indicate heterogeneous catalyst 1 presents high efficiency (yield = 98%), excellent selectivity (>99%), and good recyclability for the oxidation of 1-(4-chlorophenyl)ethanol to 4'-chloroacetophenone with commercially available 70% aqueous tert-butyl hydroperoxide {TBHP (aq.)} as the oxidant at room temperature.

10.
J Opioid Manag ; 17(7): 153-158, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34520036

RESUMO

We report a case in which sublingual buprenorphine was used to help transition a patient off intravenous (IV) opioid analgesics medications post-multiple abdominal procedures. Intravenous opioids are commonly used in inpatient surgical pain management for patients with severe pain who are unable to take oral medications. Typically, a short course of IV analgesics is used, followed by transition to oral analgesic regimen. However, in patients with poor gastrointestinal absorption, pain control can be challenging. We present this case to highlight how sublingual buprenorphine can be a useful agent for acute pain management, especially when conventional strategies provide suboptimal responses.


Assuntos
Analgésicos Opioides , Buprenorfina , Analgésicos Opioides/efeitos adversos , Buprenorfina/efeitos adversos , Combinação Buprenorfina e Naloxona , Humanos , Dor , Manejo da Dor
11.
Nurs Health Sci ; 23(4): 880-887, 2021 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-34455669

RESUMO

In this cross-sectional study, we explored the current status and the correlates of self-perceived transcultural self-efficacy among nurses working in a tertiary hospital in Hangzhou, China. A total of 336 nurses (age range, 24-50 years) completed the Chinese version of the Transcultural Self-Efficacy Tool. The majority of respondents were female (94.64%), and 67.26% were government employees. Between group differences were assessed using the rank sum test. Most nurses had a below-moderate level of self-perceived transcultural self-efficacy in all subscales (Cognitive [67.69%]; Practical [71.65%], Affective [66.75%]). Age, professional title, employment type, and income level had a significant influence on all three subscale scores of the survey instrument. Our findings highlight the need for inclusion of transcultural nursing in the continuing education curricula for nurses. Nursing managers should target continuing education based on the demographic characteristics of nurses. Hospital managers should consider minimizing the pay disparity between government-employed and temporary nurses. These initiatives can help improve the quality of nursing care in a cross-cultural milieu.

12.
Artigo em Inglês | MEDLINE | ID: mdl-34334385

RESUMO

BACKGROUND: Acoustic Radiation Force Impulse (ARFI), Fibrosis-4(FIB-4) and Aspartate transaminase to platelet ratio index (APRI) are valuable non-invasive methods to evaluate fibrosis in hepatitis virus. Yet, they are rarely used in Wilson's disease. OBJECTIVE: Evaluate the diagnostic efficacy of ARFI, FIB-4, APRI, combined detection in cirrhosis with WD, and speculate the optimal high, low cutoff. METHODS: This retrospective study was authorized by hospital ethics Committee (number:2021MCZQ02). 102 patients with WD completed ARFI and laboratory examination on the same day. The intraclass correlation coeffcient (ICC) of ARFI among three sonographers was 0.896 (95%CI:0.859-0.925, p = 0.000). The stage of liver involvement was classified into 5 categories according to clinical manifestations, laboratory examination, and liver morphologic characteristics: I, normal; II, biochemical abnormal only; III, abnormal liver morphologic features without sighs of cirrhosis; IV, clinical and imaging sighs of compensateded cirrhosis (Child-Pugh A); V, decompensated cirrhosis (Child-Pugh B and C). This stage system served as the reference standard. The diagnostic efficacy was analyzed by Logistic regression, ROC curve. The optimal low cut-off with high sensitivity (SE) and low negative likelihood ratio (NLR) and high cut-off with high specificity (SP) and positive likelihood ratio (PLR) were derived. RESULTS: The diagnostic value of ARFI (0.85, 95%CI:0.77-0.92, p = 0.000) in distiguishing cirrhosis with WD was higher than FIB-4 (0.59, 95%CI: 0.47-0.70, p = 0.127), APRI (0.70, 95%CI: 0.59-0.81, p = 0.000). The low, high cut-off of ARFI for excluding, diagnosing cirrhosis with WD was 1.47 m/s(SE: 98%, NLR:0.09), 2.11 m/s(SP:98%, PLR:27.4), 37 (36%) patients could be spared a liver biopsy. When ARFI was 1.47∼2.11 m/s, liver biopsy was recommended. After combined with ARFI, the AUROC of FIB-4, APRI were increased respectively (p <  0.001), there were not different between ARFI and combined detection(p >  0.05). CONCLUSION: ARFI could replace some unnecessary liver biopsy according to high diagnostic efficacy for identifying cirrhosis of WD. The combined detection can also be used as an important model to predict cirrhosis in WD.

13.
Cureus ; 13(4): e14426, 2021 Apr 11.
Artigo em Inglês | MEDLINE | ID: mdl-34079650

RESUMO

Laryngospasm is an uncommon complication of anesthesia in adults but more common in pediatric anesthesia, which could present similarly to supraglottic upper airway obstruction. The management of such airway complications is even more difficult in patients with difficult mask ventilation and intubation. Our case illustrated the management of laryngospasm and negative pressure pulmonary edema in a patient with Treacher Collins syndrome. A literature search revealed few previous similar reports. We demonstrated an algorithm to differentiate between the true laryngospasm from the supraglottic upper airway obstruction, the management of laryngospasm in patients with difficult airways, and the recognition and management of negative pressure pulmonary edema as a complication of laryngospasm.

14.
Anesth Analg ; 133(3): 620-629, 2021 09 01.
Artigo em Inglês | MEDLINE | ID: mdl-34153021

RESUMO

BACKGROUND: Peripheral nerve block (PNB) with perineural local anesthetic is used for anesthesia or analgesia with many benefits. To extend these benefits, various adjuvant drugs have been used to prolong the duration of analgesia. We aimed to evaluate the effectiveness of various adjuvants at prolonging the duration of sensory and motor blockade for PNB. METHODS: A network meta-analysis of placebo-controlled and active randomized controlled trials was performed comparing 10 adjuvants. Embase, PubMed, Web of Science, and Cochrane library were searched, with articles before May 21, 2020 included. Two authors independently selected studies and extracted data. The primary outcomes were sensory block (SB) and motor block (MB) time, and the secondary outcome was time of first analgesia rescue (FAR). Effect size measures were described as mean differences (MD) with 95% confidence intervals (CIs). Confidence in evidence was assessed using Confidence in Network Meta-Analysis (CINeMA). The study protocol was preregistered with the prospectively registered systematic reviews in health and social care international database (PROSPERO), as number CRD42020187866. RESULTS: Overall 16,364 citations were identified, of which 53 studies were included with data for 3649 patients. In network meta-analyses, 4 of 7 included treatment strategies were associated with more efficacious analgesia compared with placebo therapy, including dexamethasone (SB time: 5.73 hours, 95% CI, 4.16-7.30; MB time: 4.20 hours, 95% CI, 2.51-5.89; time of FAR: 8.71 hours, 95% CI, 6.63-10.79), dexmedetomidine (SB time: 4.51 hours, 95% CI, 3.52-5.50; MB time: 4.04 hours, 95% CI, 2.98-5.11; time of FAR: 5.25 hours, 95% CI, 4.08-6.43), fentanyl (SB time: 3.59 hours, 95% CI, 0.11-7.06; MB time: 4.42 hours, 95% CI, 0.78-8.06), and clonidine (SB time: 2.75 hours, 95% CI, 1.46-4.04; MB time: 2.93 hours, 95% CI, 1.69-4.16; time of FAR: 3.35 hours, 95% CI, 1.82-4.87). In a subgroup analysis, addition of dexamethasone to ropivacaine significantly increased the time of FAR when compared to dexmedetomidine (time of FAR: 5.23 hours, 95% CI, 2.92-7.54) or clonidine (time of FAR: 6.61 hours, 95% CI, 4.29-8.92) with ropivacaine. CONCLUSIONS: These findings provide evidence for the consideration of dexmedetomidine, dexamethasone, and clonidine as adjuvants to prolong the duration of PNB. The addition of dexamethasone to ropivacaine has a longer time of FAR compared with clonidine or dexmedetomidine.


Assuntos
Adjuvantes Anestésicos/administração & dosagem , Anestésicos Locais/administração & dosagem , Atividade Motora/efeitos dos fármacos , Bloqueio Nervoso , Sistema Nervoso Periférico/efeitos dos fármacos , Limiar Sensorial/efeitos dos fármacos , Adjuvantes Anestésicos/efeitos adversos , Anestésicos Locais/efeitos adversos , Clonidina/administração & dosagem , Dexmedetomidina/administração & dosagem , Esquema de Medicação , Interações Medicamentosas , Humanos , Bloqueio Nervoso/efeitos adversos , Metanálise em Rede , Medição de Risco , Fatores de Risco , Fatores de Tempo
15.
Inorg Chem ; 60(11): 8164-8172, 2021 Jun 07.
Artigo em Inglês | MEDLINE | ID: mdl-34014645

RESUMO

A series of benzoate-decorated lanthanide (Ln)-containing tetrameric Dawson-type phosphotungstates [N(CH3)4]6H20[{(P2W17O61)Ln(H2O)3Ln(C6H5COO)(H2O)6]}{[(P2W17O61)Ln(H2O)3}]2Cl2·98H2O [Ln = Sm (1), Eu (2), and Gd (3)] were made using a facile one-step assembly strategy and characterized by several techniques. Notably, the Ln-containing tetrameric Dawson-type polyoxoanions [{(P2W17O61)Ln(H2O)3Ln(C6H5COO)(H2O)6]}{[(P2W17O61)Ln(H2O)3}]224- are all established by four monolacunary Dawson-type [P2W17O61]10- segments, encapsulating a Ln3+ ion with two benzoates coordinating to the Ln3+ ions. 1-3 exhibit reversible photochromism, which can change from intrinsic white to blue for 6 min upon UV irradiation, and their colors gradually recover for 30 h in the dark. The solid-state photoluminescence spectra of 1 and 2 display characteristic emissions of Ln components based on 4f-4f transitions. Time-resolved emission spectra of 1 and 2 were also measured to authenticate the energy transfer from the phosphotungstate and organic chromophores to Eu3+. In particular, 1 shows an effectively switchable luminescence behavior induced by its fast photochromism.

16.
Inorg Chem ; 60(11): 7753-7761, 2021 Jun 07.
Artigo em Inglês | MEDLINE | ID: mdl-34019402

RESUMO

Developing new catalysts for highly efficient and selective oxidation of saturated C-H bonds is significant due to their thermodynamic strength. Via incorporation of PW12O403-, pyridine-2,5-dicarboxylic acids (pydc), and Fe(III) ions into one framework, a new polyoxometalate-based metal-organic framework, [HFe4O2(H2O)4(pydc)3PW12O40]·10.5H2O (FeW-PYDC), was successfully prepared by a hydrothermal method. Interestingly, FeW-PYDC features a three-dimensional porous structure with {Fe4O2} interconnecting with PW12O403- units. FeW-PYDC displayed excellent performance in the selective oxidation of C-H bonds of alkylbenzenes with high conversion (95.7%) and selectivity (96.6%). As an effective heterogeneous catalyst, FeW-PYDC demonstrates good reusability and structural stability.

17.
Dalton Trans ; 50(22): 7610-7620, 2021 Jun 08.
Artigo em Inglês | MEDLINE | ID: mdl-33988637

RESUMO

Three structurally intriguing polyoxoniobates (PONbs) based on the trivacant B-type α-Keggin ion {TeNb9O33}, H4K(CN3H6)2{[Cu4(2,2'-bipy)4(H2O)2][TeNb9V2O37]}·29H2O (1, 2,2'-bipy = 2,2'-bipyridine), H0.5K5Na2.5{[Cu(en)H2O]3[TeNb9V3O39]}·10H2O (2, en = ethylenediamine), and K3Na5{[Cu(1,3-dap)H2O]3[TeNb9V3O39]}·11H2O (3, 1,3-dap = 1,3-diaminopropane), are assembled by the conventional aqueous solution methods using a series of N-containing organic ligands. In 1, each of the two {VO4} units is attached to two coplanar NbO6 octahedra on the {Nb3O13} cluster of the {TeNb9O33} unit. Differently, three {VO4} units in 2 and 3 are linked to two edge-sharing NbO6 octahedra, respectively. Compounds 1-3 represent the first oxo NbTeV clusters and also the first vanadoniobates based on the trivacant Keggin PONb units. All three compounds were characterised by single-crystal X-ray structural analysis, TGA and IR, ESI-MS and 51V NMR spectroscopy. Furthermore, the magnetic properties of compounds 1 and 2 were also studied.

18.
J Biol Chem ; 297(1): 100841, 2021 07.
Artigo em Inglês | MEDLINE | ID: mdl-34058201

RESUMO

SGNH-type acetyl xylan esterases (AcXEs) play important roles in marine and terrestrial xylan degradation, which are necessary for removing acetyl side groups from xylan. However, only a few cold-adapted AcXEs have been reported, and the underlying mechanisms for their cold adaptation are still unknown because of the lack of structural information. Here, a cold-adapted AcXE, AlAXEase, from the Arctic marine bacterium Arcticibacterium luteifluviistationis SM1504T was characterized. AlAXEase could deacetylate xylooligosaccharides and xylan, which, together with its homologs, indicates a novel SGNH-type carbohydrate esterase family. AlAXEase showed the highest activity at 30 °C and retained over 70% activity at 0 °C but had unusual thermostability with a Tm value of 56 °C. To explain the cold adaption mechanism of AlAXEase, we next solved its crystal structure. AlAXEase has similar noncovalent stabilizing interactions to its mesophilic counterpart at the monomer level and forms stable tetramers in solutions, which may explain its high thermostability. However, a long loop containing the catalytic residues Asp200 and His203 in AlAXEase was found to be flexible because of the reduced stabilizing hydrophobic interactions and increased destabilizing asparagine and lysine residues, leading to a highly flexible active site. Structural and enzyme kinetic analyses combined with molecular dynamics simulations at different temperatures revealed that the flexible catalytic loop contributes to the cold adaptation of AlAXEase by modulating the distance between the catalytic His203 in this loop and the nucleophilic Ser32. This study reveals a new cold adaption strategy adopted by the thermostable AlAXEase, shedding light on the cold adaption mechanisms of AcXEs.


Assuntos
Acetilesterase/química , Acetilesterase/metabolismo , Adaptação Fisiológica , Temperatura Baixa , Acetilesterase/antagonistas & inibidores , Acetilesterase/genética , Sequência de Aminoácidos , Bactérias/enzimologia , Domínio Catalítico , Inibidores Enzimáticos/farmacologia , Estabilidade Enzimática/efeitos dos fármacos , Cinética , Metais/farmacologia , Modelos Moleculares , Simulação de Dinâmica Molecular , Mutação/genética , Filogenia , Multimerização Proteica , Especificidade por Substrato/efeitos dos fármacos , Temperatura
19.
Nanoscale ; 13(17): 8077-8086, 2021 May 06.
Artigo em Inglês | MEDLINE | ID: mdl-33899868

RESUMO

Five-coordinate geometry around ruthenium with highly exposed active sites has attracted intensive scientific interest due to its superior properties and extensive applications. Herein, we report a series of structurally controllable multi-Ru-bridged polyoxometalates, K5NaH10[{Ru4(H2O)n}(WO2)4(AsW9O33)4]·mH2O {1, 1-dehyd-373K, 1-dehyd-473K, 1-dehyd-573K; n = 4, m = 36; n = 4, m = 6; n = 4, m = 0; n = 0, m = 0} fabricated through a feasible assembly strategy using arsenotungstate {2, KNa12H17Cl2(As4W40O140)·29H2O} as a structure-directing unit. Systematic characterization methods identified that the six-coordinate geometry can successfully transform into five-coordinate geometry about active sites (Ru) by removing aqua ligands under high reaction temperatures. All the multi-Ru-bridged polyoxometalates demonstrated strong stability and catalytic effectiveness in the transformation of 1-(4-chlorophenyl)ethanol to 4'-chloroacetophenone under very mild conditions. 1-dehyd-573K, specifically, achieves the best catalytic effectiveness with a turnover frequency (TOF) = 25 100·h-1 owing to its unique five-coordinate geometry on the Ru sites. To our knowledge, 1-dehyd-573K outperforms other POM-based catalysts in the oxidative catalysis of 1-(4-chlorophenyl)ethanol. The heterogeneous polyoxometalates were also proven to be strongly reusable, with their structural integrities well maintained after multiple-cycle catalytic reactions.

20.
Chem Commun (Camb) ; 57(33): 3999-4002, 2021 Apr 22.
Artigo em Inglês | MEDLINE | ID: mdl-33885695

RESUMO

A 72-nuclearity niobium cluster was synthesized, in which two {CuNb26O76} clusters and one {Nb20O59} cluster are fused in a triangular fashion, resulting in a {Nb12} cavity. Further, the simple nature of the species allowed its investigation by ESI-MS analysis, yielding two subunits with time.

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