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1.
Abdom Radiol (NY) ; 2021 Feb 10.
Artigo em Inglês | MEDLINE | ID: mdl-33566165

RESUMO

OBJECTIVE: To explore which computed tomography (CT) features can predict pathological complete response (pCR) (ypT0N0) after neoadjuvant chemotherapy (NAC) in patients with gastric adenocarcinoma (GC). MATERIALS AND METHODS: This study reviewed an institutional database of patients who underwent resection of GC after NAC and identified patients with pCR from January 2010 to December 2013. The correlations between pre-chemotherapy and post-chemotherapy CT features and pCR were analyzed. RESULTS: Eleven of 199 patients with GC who achieved ypT0N0 status after NAC were classified as the pCR group in this study. After matching pCR (n = 11) and non-pCR patients (n = 44) in the ratio of 1:4, a total of 55 cases were analyzed. The binary logistic regression analysis showed that the post-chemotherapy short diameter of the largest lymph node and tumor thickness ratio reduction were independent predictors of pCR, with an area under the curve (AUC) of 0.94 on the receiver operating characteristic (ROC) curve analysis. CONCLUSION: Two CT features, including the short diameter of the largest lymph node post-chemotherapy and tumor thickness ratio reduction, are good predictors of pCR after NAC in patients with GC.

2.
Chin Med J (Engl) ; 133(23): 2829-2839, 2020 Dec 05.
Artigo em Inglês | MEDLINE | ID: mdl-33273332

RESUMO

BACKGROUND: Acute myeloid leukemia (AML) is a malignant hematological disease, originating from hematopoiesis stem cell differentiation obstruction and clonal proliferation. New reagents or biologicals for the treatment of AML are urgently needed, and exosomes have been identified as candidate biomarkers for disease diagnosis and prognosis. This study aimed to investigate the effects of exosomes from bone marrow mesenchymal stem cells (BMSCs) on AML cells as well as the underlying microRNA (miRNA)-mediated mechanisms. METHODS: Exosomes were isolated using a precipitation method, followed by validation using marker protein expression and nanoparticle tracking analysis. Differentially expressed miRNAs were identified by deep RNA sequencing and confirmed by quantitative real-time polymerase chain reaction (qPCR). Cell proliferation was assessed by the 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium inner salt method, and cell cycle progression and apoptosis were detected by flow cytometry. Functional gene expression was analyzed by qPCR and Western blotting (WB). Significant differences were determined using Student's t test or analysis of variance. RESULTS: BMSCs-derived exosomes effectively suppressed cell proliferation (both P < 0.0001 at 10 and 20 µg/mL) and cell cycle progression (P < 0.01 at G0-G1 stage), and also significantly enhanced cell apoptosis (P < 0.001) in KG-1a cells. There were 1167 differentially expressed miRNAs obtained from BMSCs-derived exosomes compared with KG-1a cell-derived exosomes (P < 0.05). Knockdown of hsa-miR-124-5p in BMSCs abrogated the effects of BMSCs-derived exosomes in regulating KG-1a such as the change in cell proliferation (both P < 0.0001 vs. normal KG-1a cell [NC] at 48 and 72 h). KG-1a cells treated with BMSCs-derived exosomes suppressed expression of structural maintenance of chromosomes 4 (P < 0.001 vs. NC by qPCR and P < 0.0001 vs. NC by WB), which is associated with the progression of various cancers. This BMSCs-derived exosomes effect was significantly reversed with knockdown of hsa-miR-124-5p (P < 0.0001 vs. NC by WB). CONCLUSIONS: BMSCs-derived exosomes suppress cell proliferation and cycle progression and promote cell apoptosis in KG-1a cells, likely acting through hsa-miR-124-5p. Our study establishes a basis for a BMSCs-derived exosomes-based AML treatment.

3.
Acta Pharmacol Sin ; 2020 Dec 14.
Artigo em Inglês | MEDLINE | ID: mdl-33318625

RESUMO

This study aimed to investigate the inhibitory effect of EM-2, a natural active monomer purified from Elephantopusmollis H.B.K., on the proliferation of human hepatocellular carcinoma cells and the molecular mechanism involved. The results from the MTT assay revealed that EM-2 significantly inhibited the proliferation of human hepatocellular carcinoma (HCC) cells in a dose-dependent manner but exhibited less cytotoxicity to the normal liver epithelial cell line LO2. EdU staining and colony formation assays further confirmed the inhibitory effect of EM-2 on the proliferation of Huh-7 hepatocellular carcinoma cells. According to the RNA sequencing and KEGG enrichment analysis results, EM-2 markedly activated the MAPK pathway in Huh-7 cells, and the results of Western blotting further indicated that EM-2 could activate the ERK and JNK pathways. Meanwhile, EM-2 induced apoptosis in a dose-dependent manner and G2/M phase arrest in Huh-7 cells, which could be partially reversed when treated with SP600125, a JNK inhibitor. Further study indicated that EM-2 induced endoplasmic reticulum stress and blocked autophagic flux in Huh-7 cells by inhibiting autophagy-induced lysosome maturation. Inhibition of autophagy by bafilomycin A1 could reduce cell viability and increase the sensitivity of Huh-7 cells to EM-2. In conclusion, our findings revealed that EM-2 not only promoted G2/M phase arrest and activated ER stress but also induced apoptosis by activating the JNK pathway and blocked autophagic flux by inhibiting autolysosome maturation in Huh-7 hepatocellular carcinoma cells. Therefore, EM-2 is a potential therapeutic drug with promising antitumor effects against hepatocellular carcinoma and fewer side effects.

4.
J Phys Chem Lett ; 11(23): 9990-9994, 2020 Dec 03.
Artigo em Inglês | MEDLINE | ID: mdl-33179926

RESUMO

It is of great importance to study the mechanisms to activate dinitrogen (N2), the very inert molecule, under mild conditions. Gas-phase metal clusters are being actively generated to react with N2 to identify new reaction types and mechanisms. Herein, an unprecedented, mechanistically unique metal atom (Fe or V) ejection in the thermal reaction of FeV2C2- with N2 has been identified using mass spectrometry, photoelectron imaging spectroscopy, and quantum chemistry calculations. Strong evidence suggests that the complete cleavage of the N≡N triple bond and subsequent functionalization of two N atoms via C-N coupling were achieved in this reaction. The complementary cooperation between V atoms with strong electron-donating ability and an Fe atom with large electron-withdrawing ability as well as the geometric flexibility of the Fe-V-V ring drives the whole reaction. The important role of C ligands in N≡N cleavage was also revealed. This study emphasizes the importance of heteronuclear metal systems for N2 fixation.

5.
J Gastrointest Oncol ; 11(5): 894-898, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-33209485

RESUMO

Background: The purpose of this study was to evaluate the health economics of patients with sepsis after gastrointestinal tumor operation in ICU. Methods: This case-control study used 1:1 propensity-score (PS) matched method and patients were matched according to tumor type, age and gender. The study group was composed of 181 patients with sepsis after operation of gastrointestinal tumor in ICU, while the control group was composed of 181 patients without sepsis after operation of gastrointestinal tumor. The medical expenses and length of stay in the hospital of these patients were analyzed. Results: The median of the total hospitalization cost for the study group was $26,038, which was 1.7 times of the control group (P<0.001). The costs of drugs, laboratory test, examination, treatment, operation, anesthesia, materials, ward and other costs in the study group were higher than those in the control group (P<0.001). The median length of stay in the hospital in the study group was 26 days, which were 12 days longer than that of the control group (P<0.001). However, there was no significant difference in daily average cost between the two groups (P=0.103). Conclusions: In ICU, patients with sepsis after operation of gastrointestinal tumor increased the cost of hospitalization and prolonged the length of stay in the hospital than those without sepsis.

6.
J Phys Chem A ; 124(38): 7749-7755, 2020 Sep 24.
Artigo em Inglês | MEDLINE | ID: mdl-32840105

RESUMO

Nitrogen (N2) fixation is a challenging and vital issue in chemistry. Inspired by the fact that the active sites of nitrogenases are polynuclear metal sulfide clusters, the reactivity of gas-phase metal sulfide clusters toward N2 has received considerable attention to gain fundamental insights into nitrogen fixation. Herein, neutral tantalum sulfide clusters have been prepared and their reactivity toward N2 has been investigated by mass spectrometry in conjunction with density functional theory (DFT) calculations. The experimental results showed that Ta3Sn (n = 0-3) could adsorb N2, while Ta3S4 was inert to N2. The DFT calculations revealed that the complete cleavage of the N≡N bond on the trinuclear metal center in the Ta3S0-3/N2 reaction systems was overall barrierless under thermal collision conditions. The sulfur ligands can facilitate the approaching of N2 toward the metal center but weaken the electron-donating ability of the metal center. The inertness of Ta3S4 is ascribed to the electron-deficient state of Ta3 in Ta3S4 and the least effective orbital interaction in the Ta3S4/N2 couple. This study provides new insights into the ligand effect on the interaction of the metal clusters with N2.

7.
Gastric Cancer ; 2020 Jul 26.
Artigo em Inglês | MEDLINE | ID: mdl-32712769

RESUMO

BACKGROUND: For patients with locally advanced proximal gastric cancer (LAPGC), the individualized selection of patients with highly suspected splenic hilar (No. 10) lymph node (LN) metastasis to undergo splenic hilar lymphadenectomy, is a clinical dilemma. This study aimed to re-evaluate the feasibility and safety of laparoscopic spleen-preserving splenic hilar lymphadenectomy (LSPSHL) and to identify the population who would benefit from it. METHODS: A total of 1068 patients (D2 group = 409; D2 + No. 10 group = 659) who underwent laparoscopic total gastrectomy from four prospective trials between January 2015 and July 2019 were analyzed. RESULTS: No significant difference in the incidence (16.9% vs. 16.4%; P = 0.837) of postoperative complications were found between the two groups. The metastasis rate of No. 10 LN among patients in the D2 + No. 10 group was 10.3% (68/659). Based on the decision tree, patients with LAPGC with tumor invading the greater curvature (Gre), patients with non-Gre-invading LAPGC with a tumor size > 5 cm and clinical positive locoregional LNs were defined as the high-priority No. 10 dissection group. The metastasis rate of No. 10 LNs in the high-priority group was 19.4% (41/211). In high-priority group, the 3-year overall survival of the D2 + No. 10 group was better than that of the D2 group (74.4% vs. 42.1%; P = 0.005), and the therapeutic index of No. 10 was higher than the indices of most suprapancreatic stations. CONCLUSIONS: LSPSHL for LAPGC is safe and feasible when performed by experienced surgeons. LSPSHL could be recommended for the high-priority group patients even without invasion of the Gre.

8.
Eur J Radiol ; 128: 108974, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32416553

RESUMO

PURPOSE: To assess the efficacy of diffusion kurtosis imaging (DKI) in the prediction of the treatment response to neoadjuvant chemotherapy in patients with locally advanced gastric cancer (LAGC). METHODS: A total of 31 LAGC patients were enrolled in this prospective study. All patients underwent diffusion-weighted MRI examination (with b = 01, 2001, 5001, 8002, 10004, 15004, 20006 s/mm2, the subscript denotes the number of signal averages) before and after chemotherapy. DKI and mono-exponential (b = 0, 800 s/mm2) models were built. Apparent diffusion coefficient (ADC), mean diffusivity (MD) and mean kurtosis (MK) of the LAGC tumors were measured. The absolute change values (ΔX) and percentage change values (%ΔX) of the above parameters post neoadjuvant chemotherapy (NACT) were calculated. The response was evaluated according to the pathological tumor regression grade scores (effective response group: TRG 0-2, poor response group: TRG 3). Mann-Whitney U test and receiver operating characteristic (ROC) curves were applicated for statistical analysis. RESULTS: There were 17 patients in the effective response group (ERG), and 14 patients in the poor response group (PRG). The MKpre and MKpost values in PRG were significantly higher than those in ERG [(0.671 ±â€¯0.026) and (0.641 ±â€¯0.019) vs. (0.584 ±â€¯0.023) and (0.519 ±â€¯0.018), p < 0.001]. ADCpost and MDpost in PRG were significantly lower than those in ERG (p = 0.005, p =0.001). Significant differences were also observed for % ΔMK, ΔMD and ΔMK between the two groups (p < 0.05). The area under the curve (AUC) for the prediction of PRG was highest for MKpost (AUC = 0.958, cutoff value = 0.614). The MKpre and MKpost had the highest sensitivity (91.70 %) and specificity (93.80 %) in the prediction of PRG, respectively. CONCLUSION: Both DKI and ADC values show potential for the prediction of the PRG in LAGC patients. The DKI parameters, especially MKpost displayed the best performance.

9.
J Laparoendosc Adv Surg Tech A ; 30(7): 713-722, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32471317

RESUMO

Background: With the rapid aging of global population, the number of elderly patients with gastric cancer is increasing. This study aimed to evaluate short- and long-term outcomes after laparoscopic gastrectomy (LG) versus open gastrectomy (OG) in elderly gastric cancer patients. Materials and Methods: We searched PubMed, EMBASE, and the Cochrane library databases from January 1994 to May 2019. Surgical safety, postoperative complications, number of harvested lymph nodes, and overall survival rate were included and analyzed. The qualities of the included studies were evaluated by Newcastle-Ottawa Quality Assessment Scale. The evidence of outcomes was evaluated using the GRADE approach. The Review Manager® 5.3 (Cochrane, London, UK) and Stata® 14.0 (StataCorp., College Station, Texas) were used to analyze the outcomes. Results: Thirteen studies containing 4768 elderly patients with gastric cancer were included in this meta-analysis. LG was more favorable than OG in terms of overall postoperative morbidity (odds ratio [OR]: 0.56; 95% confidence interval [CI]: 0.44 to 0.70; P < .00001), the postoperative stay (standardized mean difference [SMD]: -0.56; 95% CI: -0.76 to (-0.37); P < .00001), and the number of harvested lymph nodes (SMD: 0.19; 95% CI: 0.09 to 0.29; P = .0003). No significant difference was found in anastomotic leakage rate (OR: 0.82; 95% CI: 0.59 to 1.12; P = .21), mental disease (OR: 0.79; 95% CI: 0.44 to 1.44; P = .44), or overall survival rate (P = .62) between two groups. However, in the subgroup with a cutoff age of 80 years, the anastomotic leakage rate was higher in LG (OR: 10.27; 95% CI: 1.31 to 80.35; P = .03). Conclusions: LG was more favorable than OG in the elderly patients <80 years old with gastric cancer.

10.
J Am Chem Soc ; 142(24): 10747-10754, 2020 Jun 17.
Artigo em Inglês | MEDLINE | ID: mdl-32450693

RESUMO

Cleavage of the triple N≡N bond by metal clusters is of fundamental interest and practical importance in nitrogen fixation. Previous studies of N≡N bond cleavage by gas-phase metal clusters emphasized the importance of the dinuclear metal centers. Herein, the dissociative adsorption of N2 and subsequent C-N coupling on trinuclear carbide cluster anions V3C4- under thermal collision conditions have been characterized by employing mass spectrometry (collision induced dissociation), cryogenic photoelectron imaging spectroscopy, and quantum chemistry calculations. A theoretical analysis identified a crucial adsorption intermediate with N2 bonded with the V3 metal core in the end-on/side-on/side-on (ESS) mode, which most likely enables the facile cleavage of the N≡N bond. Such a vital N2 coordination in the ESS mode is a result of symmetry-matched interactions between the occupied orbitals of the metal core and both of the two empty π* orbitals of N2. Furthermore, carbon ligands also play a considerable role in enhancing the reactivity of the metal core toward N2. This study strongly suggests a new mechanism of N≡N bond cleavage by gas-phase metal clusters.

11.
Ann Surg Oncol ; 27(4): 1103-1109, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31965376

RESUMO

BACKGROUND: Preoperative diagnosis of peritoneal metastasis with gastric cancer remains challenging. This study explored the abnormal computed tomography (CT) signs of occult peritoneal metastasis (OPM) and evaluated it by region-to-region comparison using staging laparoscopy, from which a 4-point CT score system was developed. METHODS: Patients with advanced gastric cancer (stage cT ≥ 2M0) diagnosed by CT were enrolled in the study. Occult peritoneal metastasis detected during staging laparoscopy was compared with preoperative CT to investigate the presence of abnormal signs by a region-to-region comparison. A 4-point CT score system was developed to define the radiologic characteristics. Subsequently, the diagnostic efficacy of the CT score system was prospectively verified. RESULTS: In this study, 57 OPM regions were detected by staging laparoscopy in 33 of the 385 enrolled patients. The greater omentum was the most frequent site of OPM (38.60%, 22/57), which usually exhibited a smudge-like ground-glass opacity (S-GGO) (90.91%, 20/22) with a mean CT score of 2.14. The parietal and perihepatic peritoneum was the second most common site (22.81%, 13/57). A 4-point CT score system was developed based on the results. A cutoff CT score of 2 or higher was associated with a false-negative rate of 2% (2/99). This CT score system had a sensitivity of 87.5% and a specificity of 76.4% for an OPM-positive diagnosis (area under the curve, 0.848). The agreement between two radiologists on the assigned final score was 76.2% (kappa, 0.5). CONCLUSIONS: Patients with OPM mostly exhibited S-GGO on CT, which should be interpreted cautiously. The 4-point CT score system may improve the pretreatment evaluation of occult peritoneal metastasis, and staging laparoscopy might not be necessary for patients with a score lower than 2.

12.
Surg Endosc ; 34(11): 5062-5073, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31823047

RESUMO

BACKGROUND: Previous retrospective studies have shown that laparoscopic spleen-preserving D2 total gastrectomy (LSTG) for advanced upper third gastric cancer (AUTGC) is safe. However, all previous studies were underpowered. We therefore conducted a prospective, multicenter study to evaluate the technical safety and feasibility of LSTG for patients with AUTGC. METHODS: Patients diagnosed with AUTGC (cT2-4a, N-/+, M0) underwent LSTG at 19 institutions between September 2016 and October 2017 were included. The number of No. 10 lymph node (LN) dissections, metastasis rates, intraoperative and postoperative complications were investigated. RESULTS: A total of 251 patients were enrolled in the study, and 242 patients were eligible for the per protocol analysis. The average numbers of No. 10 LN dissections and metastases were 2.4 and 0.1, respectively. Eighteen patients (7.4%) had No. 10 LN metastases, and among patients with advanced gastric cancer, the rate of No. 10 LN metastasis was 8.1% (18/223). pN3 status was an independent risk factor for No. 10 LN metastasis. Intraoperative complications occurred in 7 patients, but no patients required conversion to open surgery or splenectomy. The overall postoperative complication rate was 13.6% (33/242). The major complication and mortality rates were 3.3% (8/242) and 0.4% (1/242), respectively. The number of retrieved No. 10 LNs, No. 10 LN metastasis and TNM stage had no significant influence on postoperative complication rates. CONCLUSION: LSTG for AUTGC was safe and effective when performed by very experienced surgeons, this technique could be used in patients who needed splenic hilar lymph node dissection.

13.
Surg Endosc ; 34(3): 1191-1199, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31236721

RESUMO

OBJECTIVES: Healing of gastric endoscopic submucosal dissection (ESD)-induced ulcer is critical for patient recovery. During ESD treatment, submucosal incisions are made with an electrosurgical knife to accomplish en bloc resections of superficial lesions. Nevertheless, excess electrocoagulation may decrease the blood supply of ESD-induced ulcer and delay the ulcer healing. The aim of this retrospective study was to evaluate the effectiveness of conservative electrocoagulation followed by porcine fibrin sealant (FS) as a wound microvessels-protective hemostatic technique in promoting the healing of ESD-induced ulcer. METHODS: A total of 332 patients with early gastric cancer (EGCs), or gastric precancerous lesion and gastric adenoma were retrospectively analyzed. Propensity score matching was used to compensate for the differences in age, gender, tumor location, resected specimen area, and pathology. One-month ulcer healing rates and delayed bleeding were compared between two matched groups (combined hemostats group and electrocautery group). RESULTS: A total of 115 matched pairs were created after propensity score matching. There was no difference in tumor location, specimen surface area, tumor differentiation and invasion depth between groups. The completed healing rate 1 month after ESD was 44.3% in combined hemostats group and 30.4% in electrocautery group (P = 0.004). There was no difference in delayed massive bleeding rate between two groups (P = 0.300). In addition, based on the multivariate regression analysis for ulcer healing rate, the use of FS (OR, 0.348, 95% CI 0.196 - 0.617, P = 0.000) and larger specimen size (OR, 2.640, 95% CI 2.015-3.458, P = 0.000) were associated with nonhealing ulcer 1 month after ESD. CONCLUSION: Applying conservative electrocoagulation followed by porcine FS as a wound microvessels-protective hemostatic technique can promote ESD-induced ulcer healing without increasing delayed bleeding.

14.
Chemistry ; 2019 Oct 21.
Artigo em Inglês | MEDLINE | ID: mdl-31637740

RESUMO

The side-on-end-on coordination of N2 can be very important to activate and functionalize this very stable molecule. However, such coordination has rarely been reported. This study reports a gas-phase species (a polynuclear vanadium nitride cluster anion [V5 N5 ]- ) that can capture N2 efficiently (12 %), and the quantum chemistry modelling suggests an unusual side-on-end-on coordination. The cluster anions were generated by laser ablation and the reaction with N2 has been characterized by mass spectrometry, photoelectron imaging spectroscopy, and density functional theory calculations. The back-donation interactions between the localized d-d bonding orbitals on the low-coordinated dual metal (V) sites and the antibonding π* orbitals of N2 are the driving forces to adsorb N2 with a high binding energy (about 2.0 eV).

15.
Angew Chem Int Ed Engl ; 58(48): 17287-17292, 2019 Nov 25.
Artigo em Inglês | MEDLINE | ID: mdl-31553114

RESUMO

Direct conversion of methane with carbon dioxide to value-added chemicals is attractive but extremely challenging because of the thermodynamic stability and kinetic inertness of both molecules. Herein, the first dinuclear cluster species, RhVO3 - , has been designed to mediate the co-conversion of CH4 and CO2 to oxygenated products, CH3 OH and CH2 O, in the temperature range of 393-600 K. The resulting cluster ions RhVO3 CO- after CH3 OH formation can further desorb the [CO] unit to regenerate the RhVO3 - cluster, leading to the successful establishment of a catalytic cycle for methanol production from CH4 and CO2 (CH4 +CO2 →CH3 OH+CO). The exceptional activity of Rh-V dinuclear oxide cluster (RhVO3 - ) identified herein provides a new mechanism for co-conversion of two very stable molecules CH4 and CO2 .

17.
J Am Chem Soc ; 141(32): 12592-12600, 2019 Aug 14.
Artigo em Inglês | MEDLINE | ID: mdl-31314515

RESUMO

Dinitrogen activation and reduction is one of the most challenging and important subjects in chemistry. Herein, we report the N2 binding and reduction at the well-defined Ta3N3H- and Ta3N3- gas-phase clusters by using mass spectrometry (MS), anion photoelectron spectroscopy (PES), and quantum-chemical calculations. The PES and calculation results show clear evidence that N2 can be adsorbed and completely activated by Ta3N3H- and Ta3N3- clusters, yielding to the products Ta3N5H- and Ta3N5-, but the reactivity of Ta3N3H- is five times higher than that of the dehydrogenated Ta3N3- clusters. The detailed mechanistic investigations further indicate that a dissociative mechanism dominates the N2 activation reactions mediated by Ta3N3H- and Ta3N3-; two and three Ta atoms are active sites and also electron donors for the N2 reduction, respectively. Although the hydrogen atom in Ta3N3H- is not directly involved in the reaction, its very presence modifies the charge distribution and the geometry of Ta3N3H-, which is crucial to increase the reactivity. The mechanisms revealed in this gas-phase study stress the fundamental rules for N2 activation and the important role of transition metals as active sites as well as the new significant role of metal hydride bonds in the process of N2 reduction, which provides molecular-level insights into the rational design of tantalum nitride-based catalysts for N2 fixation and activation or NH3 synthesis.

18.
J Am Soc Mass Spectrom ; 30(10): 1956-1963, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31236780

RESUMO

Dinitrogen (N2) activation by metal hydride species is of fundamental interest and practical importance while the role of hydrogen in N2 activation is not well studied. Herein, the structures of Co3Dn- (n = 0-4) clusters and their reactions with N2 have been studied by using a combined experimental and computational approach. The mass spectrometry experiments identified that the Co3Dn- (n = 2-4) clusters could adsorb N2 while the Co3Dn- (n = 0 and 1) clusters were inert. The photoelectron imaging spectroscopy indicated that the electron detachment energies of Co3D2-4- are smaller than those of Co3D0,1-, which characterized that it is easier to transfer electrons from Co3D2-4- than from Co3D0,1- to activate N2. The density functional theory calculations generally supported the experimental observations. Further analysis revealed that the H atoms in the Co3Hn- (n = 2-4) clusters generally result in higher energies of the Co 3d orbitals in comparison with the Co3Hn- (n = 0 and 1) systems. By forming chemical bonds with H atoms, the Co atoms of Co3H2-4- are less negatively charged with respect to the naked Co3- system, which leads to higher N2 binding energies of Co3H2-4N2- than that of Co3N2-.

19.
Inorg Chem ; 58(8): 4701-4705, 2019 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-30931560

RESUMO

The construction of C-N bonds by the direct incorporation of dinitrogen (N2) instead of ammonia (NH3) into active species is particularly desirable but has been rarely reported. Herein, a ditantalum carbide cluster anion (Ta2C4-) capable of cleaving the N≡N bond and constructing a C-N bond under mild conditions has been identified using mass spectrometry, photoelectron imaging spectroscopy, and quantum-chemical calculations. The photoelectron spectrum of Ta2C4N2- is remarkably different from that of Ta2C4- and matches the simulated spectrum of the Ta2C4N2- species with an end-on-bonded CN unit. The formation of the C-N bond has also been supported by the CN- fragment observed in the collision-induced dissociation of Ta2C4N2-. The exceptional reactivity of Ta2C4- is ascribed to the low-valent metal center serving as an electron reservoir. This study provides a non-NH3 route to construct C-N bonds by incorporating N2 into carbide compounds to produce nitrogenous species.

20.
Jpn J Radiol ; 37(7): 518-525, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-30941618

RESUMO

PURPOSE: To investigate the correlation between the preoperative CT findings in diagnosis of gastric bare area (GBA) invasion and the 3-year-overall survival (OS) of patients with proximal gastric carcinoma (PGC). METHODS: 108 consecutive patients with PGC confirmed by biopsy underwent MDCT scan prior to gastrectomy were enrolled retrospectively from Dec 2009 to Dec 2014. GBA invasion in PGC were evaluated by measuring the direct CT signs including transmural involvement and lymph nodes in the GBA. The indirect signs were also evaluated including the infiltration of the diaphragm, gastrophrenic ligament and perigastric fat. Kaplan-Meier estimates with log-rank test and Cox proportional hazard model were used for analysis. RESULTS: The two raters achieved excellent agreement. Univariate Kaplan-Meier estimates indicated that postoperative chemotherapy (p = 0.003), transmural involvement (p < 0.001), lymph nodes in the GBA (p = 0.015) and cT staging (p = 0.002) were associated with OS. Cox proportional hazard model indicated that the transmural involvement (HR = 8.194, 95% CI 2.15-31.266), diaphragm involvement (HR = 0.21, 95% CI 0.042-0.986), perigastric fat infiltration (HR = 0.125, 95% CI 0.018-0.885; HR = 0.02, 95% CI 0.001-0.264), and cT staging were independent prognostic factors for OS. CONCLUSION: CT findings of GBA invasion in patients with PGC, not only the transmural involvement but also the indirect signs are independent prognostic factors potentially, which should be given more emphasis in future clinical practice.


Assuntos
Tomografia Computadorizada Multidetectores/métodos , Neoplasias Gástricas/diagnóstico por imagem , Biópsia , Feminino , Gastrectomia , Humanos , Estimativa de Kaplan-Meier , Masculino , Pessoa de Meia-Idade , Invasividade Neoplásica , Cuidados Pré-Operatórios/métodos , Prognóstico , Modelos de Riscos Proporcionais , Estudos Retrospectivos , Estômago/diagnóstico por imagem , Estômago/patologia , Neoplasias Gástricas/patologia
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