Theoretical Study on the Mechanism of the Hydrogenation of Azo (N═N) Bonds to Amines Catalyzed by Manganese.

The mechanism of the transition metal manganese complex Mn(PhPNN)(CO)2Br (CA-4) that catalyzed the hydrogenation of the azo (N═N) bond to amines has been investigated using the PBE0 function. The results show that the whole reaction involves three basic processes: (1) the addition of H2 to CA gives IN2, which can hydrogenate the azo (N═N) bond at the later stage; (2) hydrogenation of azobenzene by IN2, which gives 1,2-diphenylhydrazine (PhNHNHPh); and (3) hydrogenation of 1,2-diphenylhydrazine by IN2, which affords aniline (PhNH2). The results suggest that the hydrogenation of CA and hydrogenation of azobenzene by IN2 to afford PhNHNHPh are easy to occur due to the low barriers, and the overall rate-determining step is the formation of IN11 and PhNH2 by breaking the N-N bond in the stage of hydrogenation of 1,2-diphenylhydrazine by IN2, with an energy barrier of 39.1 kcal/mol. The computed results are in good agreement with the experimental results. The mechanism of the azobenzene reaction catalyzed by manganese was analyzed by charge and orbital analysis in detail. The theoretical results provide a deeper understanding of the mechanism and fully explain the experimental facts.

Computational Insight into the Mechanism of Ruthenium(II)-Catalyzed α-Alkylation of Arylmethyl Nitriles Using Alcohols.

The ruthenium(II)-catalyzed α-alkylation reaction of arylmethyl nitriles (phenylacetonitrile) using alcohols (ethanol) in toluene has been extensively investigated by means of SMD-M06-2X/6-311G(d,p)-LANL2dz (LAnL2dz for Ru, 6-311G(d,p) for other atoms) calculations. Detailed mechanistic schemes have been proposed and discussed. The catalytically active Ru(II) complex was generated by the base-induced KCl elimination from the catalyst precursor [(PNPPh)RuHCl(CO)]. The overall Ru(II) catalytic cycle consists of three basic processes: (1) ethanol-to-aldehyde transformation catalyzed by the 16-electron unsaturated ruthenium pincer catalyst; (2) a 16-electron unsaturated ruthenium pincer catalyst catalyzed condensation reaction of arylmethyl nitrile with aldehyde, which leads to PhC(CN)=CHCH3; (3) hydrogenation of PhC(CN)=CHCH3, which leads to the formation of the α-alkylated arylmethyl nitrile product (PhCH(CH2CH3)CN). The DFT results revealed that the rate-determining barrier of the overall reaction was 23.9 kcal/mol of the H-transfer step in the third process. The reaction of PhC(CN)=CHCH3 with the dihydride Ru complex, which is generated in the ethanol-to-aldehyde transformation process, is the more preferable hydrogenation mechanism than hydrogenation of vinyl nitrile-Ru complex by H2. Using alcohol as the reactant not only fulfills the requirement of the borrowing-H strategy but also lowers the barriers of the H-migration steps.

[Effect of silencing AEG-1 with small interfering RNA on the proliferation and cell cycle of gastric carcinoma SGC-7901 cells].

OBJECTIVE: To explore the effect of down-regulation of astrocyte elevated gene-1 (AEG-1) expression on cell proliferation and cell cycle of gastric carcinoma cells, and its possible molecular mechanism. METHODS: Control siRNA and AEG-1 siRNA were transfected into gastric carcinoma SGC-7901 cells. 48 h after transfection, the cells were divided into 3 groups including untransfected, siRNA control and AEG-1 siRNA transfection groups. Expressions of AEG-1 mRNA and protein in the 3 group cells were detected by real-time quantitative PCR and Western blot. The changes of cell proliferation were examined using CCK-8 kit, and the cell cycle distribution was detected by flow cytometry. Finally, expressions of cell proliferation and cell cycle related proteins were detected by Western blot. RESULTS: Real-time quantitative PCR and Western blot demonstrated that compared with the untransfected and siRNA control groups, expressions of AEG-1 mRNA and protein were significantly down-regulated in the AEG-1 siRNA transfection group (P < 0.05), but there was no significant difference between the untransfected and siRNA control groups (P > 0.05). Furthermore, in vivo experiment confirmed a significant down-regulation of AEG-1 protein in the AEG-1 siRNA transfection group (P < 0.05). In addition, AEG-1 siRNA obviously inhibited the proliferation of SGC-7901 cells at different time points after transfection with AEG-1 siRNA. The percentage of cells in G0/G1 phase in the AEG-1 siRNA transfection group [(61.26 ± 1.25)%] was significantly higher than those in the untransfected group [(46.17 ± 1.91)%] and siRNA control group [(46.46 ± 1.96)%], and there was a significant difference between them (all P < 0.001). Furthermore, the result of Western blotting revealed that down-regulation of AEG-1 expression evoked the down-regulation of cdk2 and cyclin D1 expressions and elevation of p21 expression in vitro and in vivo. CONCLUSIONS: The inhibition of cell proliferation and cell cycle arrest mediated by down-regulation of AEG-1 expression may be closely associated with the changes of expression of cell cycle related proteins including cdk2, cyclin D1 and p21.

Transforming growth factor ß1-509C/T and +869T/C polymorphisms on the risk of upper digestive tract cancer: a meta-analysis based on 10,917 participants.

The aim of this study was to assess the relationships between transforming growth factor ß1-509C/T (rs1800469) and +869T/C (rs1800470) polymorphisms and the risk of upper digestive tract cancer (UDT cancer) by using a meta-analysis. We interrogated the databases of Medline, Embase and Wanfang (Chinese literature database) (latest update; December 15, 2011). Odds ratios (OR) and corresponding 95% confidence intervals (95% CI) were used to assess the strength of the associations. In total, 20 case-control studies were included in this meta-analysis. Overall, both TGF ß1-509C/T and +869T/C polymorphisms were not associated with risk of UDT cancer [-509C/T: OR (95%CI) = 1.10 (0.99-1.22) for TT vs. C carries, P(heterogeneity) = 0.10; +869T/C: OR (95%CI) = 1.04 (0.88-1.23) for CC vs. T carriers, P(heterogeneity) = 0.02]. Subgroup analyses indicated that the -509T allele was associated with increased risk of UDT cancer in population-based studies (OR = 1.16 (1.04-1.31), P(heterogeneity) = 0.31 for TT vs. C carriers) and in small sample-sized studies (OR = 1.45 (1.15-1.84), P(heterogeneity) = 0.56 TT vs. C carriers). All subgroup analyses for the TGF ß1+869T/C polymorphism indicated null association except for hepatocellular carcinoma. Interestingly, both the TGF ß1-509T allele and the +869C allele were associated with decreased risk of hepatocellular cancer based on limited original studies. This meta-analysis indicated that TGF ß1-509C/T rather than +869T/C is a potential risk factor for UDT cancer.

[Effects of KIAA0101 expression on proliferation and invasion of gastric carcinoma MKN-45 cells].

OBJECTIVE: To investigate the expression of KIAA0101 protein in gastric carcinoma cells, and to explore the effects of its down-regulation on the cell proliferation, cell cycle and invasion. METHODS: Western blot was used to detect KIAA0101 protein expression in three gastric carcinoma cell lines including MKN-28, SGC-7901 and MKN-45. KIAA0101 siRNA and control siRNA were utilized to transfect MKN-45 cells, respectively. CCK-8 was used to analyze the changes of cell proliferation, and flow cytometry to examine the changes of cell cycle distribution. Finally, Boyden chamber was used to detect the ability of cell invasion. RESULTS: Relative level of KIAA0101 protein in MKN-45 cells was significantly higher than those in MKN-28 and SGC-7901 cells, and there was significant difference among the three cell lines (P < 0.05). The result of CCK-8 study demonstrated that, compared with untreated group and control siRNA group, the proliferation of MKN-45 cells in KIAA0101 siRNA group was significantly inhibited (P < 0.05). Additionally, the result of cell cycle analysis revealed that the percentage of cell number in G(0)/G(1) phase in KIAA0101 siRNA group [(61.47 ± 0.89)%] was significantly higher than those in untreated group [(47.43 ± 0.85)%] and control siRNA group [(48.43 ± 0.73)%; F = 271.653, P = 0.000]. Further, Boyden chamber assay showed that the cell numbers migrated to Matrigel in KIAA0101 siRNA group (61.51 ± 4.76) were significantly lower than those in untreated group (138.74 ± 10.16) and control siRNA group (132.93 ± 11.25; F = 65.949, P = 0.000). CONCLUSIONS: Down-regulation of KIAA0101 expression leads to an inhibition of cell proliferation, cell cycle and cell invasion. It may provide a novel target for the treatment of patients with gastric carcinoma.

Tracheobronchial intubation using flexible bronchoscopy in children with Pierre Robin sequence: Nursing considerations for complications.

BACKGROUND: It has been shown that children with Pierre Robin sequence (PRS) have a higher risk of difficult intubation before surgery. When mask ventilation or tracheobronchial intubation is expected to be challenging, flexible bronchoscopy (FB) is advantageous in airway safety when it is used to guide tracheobronchial intubation (TI). AIM: To evaluate the complications of TI using FB in children with PRS and explore the effect of nursing services on postoperative complications. METHODS: One hundred and five children with PRS underwent TI using FB before early mandibular distraction osteogenesis. One hundred and eight children with common pneumonia who did not have a difficult airway were set as the control group. Demographic data, success rates of TI, time required for TI, number of TI attempts, and the incidence of postoperative complications were assessed. Besides, the strategies used to attenuate complications were investigated. RESULTS: The success rate of TI was 100% in children with PRS, while the success rate at the first attempt in the PRS group was significantly lower than that in the control group (88.6% vs 98.2%, P = 0.005). The time required for TI in the PRS group was markedly longer than that in the control group (P < 0.001). Children in the PRS group required repetitive operations to enter the glottis successfully (P = 0.017). The incidence of complications was noticeably higher in the PRS group (50/105, 47.6%) than in the control group (36/108, 33.3%) (P = 0.034). Seven of 105 PRS children experienced laryngeal edema (LE) (6.7%), compared with one (0.9%) in the control group (P = 0.034). Out of the seven patients who had LE, all were reintubated and managed with steroids: six recovered with inhaled steroids alone before extubated, and one was given systemic corticosteroids before recovery. CONCLUSION: FB contributes to a high success rate of TI in children with PRS. To prevent LE, operators should pay more attention to catheter material, catheter lubrication and intubation time.

[Effect of blockade of NF-kappaB signaling pathway on cell apoptosis in cutaneous squamous cell carcinoma].

OBJECTIVE: To evaluate the siRNA-mediated inhibitory effect of nuclear factor-kappaB (NF-kappaB) p65 on expression of p65, and explore the effect of blockade of NF-kappaB signal pathway on cell apoptosis in cutaneous squamous cell carcinoma (cutaneous SCC). METHODS: Cutaneous SCC cell line SCL-1 cells were transfected with 50 nmol/L p65 siRNA. The expression level of p65 mRNA was measured using RT-PCR method at 0, 24, 48 and 72 h . Expressions of p65, bcl-2 and bax proteins were determined using Western blotting. Activities of caspase-3/9 was detected by Caspase-Glo®-3/7, 8 and 9 kit. Finally, cell apoptosis was detected using flow cytometry. RESULTS: The expression level of p65 mRNA in Cutaneous SCC SCL-1 cells was obviously down-regulated 48 h after transfection with p65 siRNA, and a significant difference was detected, as compared with 0 h after (0.23 ± 0.10 vs. 0.66 ± 0.05, P<0.05). The protein levels of p65 and bcl-2 decreased, and the bax protein level and activities of caspase-3/9 increased after transfection with p65 siRNA at h 48 . Further, the results of flow cytometry demonstrated that p65 siRNA could induce apoptosis of SCL-1 cells, and cell apoptosis ratio (20.28% ± 1.87%) in p65 siRNA group was significantly higher than that in the untreated group and control siRNA group (9.13% ± 1.51% and 9.37% ± 1.38%, respectively, F=47.532, P<0.01). CONCLUSION: p65 siRNA can block NF-kappaB signal pathway, down-regulate expression of bcl-2, elevate the bax level and increase the activities of caspase-3/9, suggesting that NF-kappaB signal pathway may be a key molecular target for therapy of cutaneous SCC.

Genetic variability of genes in NER pathway influences the treatment outcome of gastric cancer.

We performed a study to investigate the role of ERCC1, ERCC2, ERCC5, XPA and XPC polymorphisms from perspective of the whole NER pathway in the prognosis of gastric cancer. A total of 410 gastric cancer patients were recruited between January 2010 and December 2011. Restriction fragment length polymorphism-polymerase chain reaction (RFLP-PCR) was used to analyze genotypes of ERCC1 rs11615 and rs3212986, ERCC2 rs13181 and s1799793, ERCC5 rs17655, XPA rs1800975 and XPC rs2228001. Our study found that carriers of ERCC1 rs3212986 TT genotype showed significantly favorable survival than wide-type GG genotype in multivariate analysis (OR=6.38, 95% CI=2.54-19.03), and patients with variant CC genotype of ERCC2 rs13181 exhibited better response to chemotherapy than those with AA genotype (OR=2.21, 95% CI=1.17-4.25). By Cox proportional hazards model, patients with variant TT genotype of ERCC1 rs3212986 exhibited longer PFS and OS than those who had GG genotype (for PFS, HR=0.37, 95% CI=0.17-0.75; for OS, HR=0.36, 95% CI=0.13-0.87). For ERCC2 rs13181 polymorphism, carriers with CC genotype demonstrated significantly increased hazards of progression of disease and death in multivariate model (for PFS, HR=0.48, 95% CI=0.26-0.88; for OS, HR=0.44, 95% CI=0.20-0.91). In conclusion, our finding suggests that ERCC1 rs3212986 and ERCC2 rs13181 gene polymorphism could influence the response to chemotherapy and clinical outcome of gastric cancer.

[Efficacy of probiotics on ulcerative colitis and its mechanism].

OBJECTIVE: To evaluate the efficacy of probiotics on the treatment outcomes of ulcerative colitis, and explore its possible mechanism. METHODS: According to the table of random number, 60 ulcerative colitis patients in our hospital were enrolled prospectively and divided into 3 groups: Golden Bifid group, Changmei group, combination group (Golden+ Changmei). Patients in Golden Bifid group received Golden Bifid 2.0 g, bid, those in Changmei group received Changmei 1.0 g, tid, and those in combination group received the above two drugs for 24 months. The clinical symptom score, colon mucosa inflammation score and endoscopic grade score were calculated and compared. IL-10 in mucosa and serum was determined by immunohistochemistry and double-antibody sandwich ELISA. RESULTS: In combined group after 24 months of treatment, clinical symptom score (12.5±2.1 vs. 2.3±0.8, P=0.016), endoscopic classification score (3.02±0.17 vs. 0.25±0.13, P=0.032), inflammatory reaction score (2.63±0.19 vs. 0.77±0.16, P=0.028) were significantly higher than those before treatment. While the scores differences of before and after treatment in Gold Bifid group and Changmei group were not statistically significant (P>0.05). IL-10 in serum [(17.4±2.2) ng/L vs. (12.8±2.2) ng/L, P=0.015] and colon mucosa [85% (17/20) vs. 55% (11/20), P=0.026] in combination group were significantly higher than those before treatment. The differences in IL-10 expression level before and after treatment were not statistically significant in the Gold Bifid group and Changmei group (P>0.05). CONCLUSION: Golden Bifid combined with Changmei as microbial ecological agents has a positive efficacy on mild to moderate ulcerative colitis, which may be associated with the up-regulation of IL-10 expression.

[Relationship between baseline heart rate and all-cause death in general population].

OBJECTIVE: To investigate the relationship between baseline heart rate(HR) and all-cause death(ACD)in general population. METHODS: 93 716 workers with heart rate between 40 bpm/min-120 bpm/min and without histories of stroke were selected from the '2006-2007 health examination records' in Kailuan and completed the electrocardiogram exam. Related information were also gathered. These subjects were followed up from July 2006 to December 2010, with the mean time of follow-up as 47.5±4.3 months. During the follow-up period, the occurrence of all-cause death was observed every half a year. RESULTS: (1)The lowest cumulative mortality rate was 1.61% in the group with 60-69 bpm/min. The lowest cumulative mortality rate was 1.78% in the group of 60-69 bpm/min in men. There was no death events observed in women with less than 50 bpm/min and the lowest cumulative mortality rate was 0.60% in the group of 80-89 bpm/min in women. (2)Data from Cox proportional hazard regression analysis showed that the RR(95%CI)of cumulative mortality rates in general population were 1.187 (1.039-1.336), 1.392(1.185-1.636), 1.733(1.404-2.139)and 2.716 (2.171-3.398)in the groups of 70-79, 80-89, 90-99 and ≥100 bpm/min, respectively. The RRs (95% CI) of cumulative mortality in men were 1.227(1.067-1.410), 1.481(1.254-1.750), 1.754 (1.406-2.188)and 2.831 (2.245-3.571) respectively. In women, when comparing with the group of 80-89 bpm/min, the RRs (95%CI)of all-cause death were 0.671(0.568-0.793), 0.825(0.703-0.970) and 1.925 (1.512-2.453)respectively in the groups of 60-69, 70-79 and ≥100 bpm/min. CONCLUSION: When HR exceeding ≥70 bpm/min, the increase of HR would also increase the rate of ACD. Results of our study also showed a J-shaped curve relation between HR and mortality.