Transient Suppression of Carrier Mobility Due to Hot Optical Phonons in Lead Bromide Perovskites.

In lead halide perovskites, owing to the strong Fröhlich coupling, carrier dynamics that governs the optoelectronic performance is greatly affected by the lattice vibrations. In this emerging class of materials, injected hot carriers quickly relax by emitting optical phonons, and if this process is sufficiently fast, hot optical phonons can be generated, which may in turn hamper the carrier transport. However, the transient interaction between hot phonons and carriers has not yet been investigated. Herein, we identified the transient absorption feature of hot phonons in lead bromide perovskites and then extracted the hot-phonon dynamics. The hot-phonon decay mechanism was uncovered by temperature-dependent measurements. The hot-phonon decay in lead bromide perovskites was an order of magnitude faster than that in GaAs, attributed to the large anharmonicity arising from the lattice softness and structural fluctuation. The carrier mobility was also transiently suppressed by hot phonons, and the mobility recovery was accompanied by the decay of hot phonons.

[Prognostic value of the tumor deposit in N0 gastric cancer by propensity score matching analysis].

OBJECTIVE: To investigate the prognostic value of tumor deposits(TD)in N0 stage gastric cancer. METHODS: A retrospective case-control study was performed on clinicopathological data of 751 N0 stage gastric cancer patients who underwent subsequent R0 gastrectomy from January 2011 to February 2013 at Zhengzhou University Affiliated Tumor Hospital. Patients were divided into TD-negative group (688 cases) and TD-positive group (63 cases). Propensity score matching was used to balance the covariances between the two groups, such as age, gender, differentiation degree, tumor location, T stage, perineural invasion, lymphovascular invasion, extent of resection, tumor size, surgical procedure,and chemotherapy. Matching was performed by the minimal adjacent method of 1:2 pairing. The survival analysis was carried out using Kaplan-Meier method,and differences between the curves were detected by log-rank test. Cox proportional hazard model was used to perform univariate analysis and multivariate analysis. RESULTS: After matching,56 patients were allocated into the TD-positive group and 112 patients into the TD-negative group, and the baseline of clinicopathological data of 2 groups matched well (all P>0.05). The median follow-up time was 55.2 (12.0-83.2) months, and 3 patients were lost to follow-up (died of other diseases). In TD-positive group, 38 patients died of gastric cancer and 1 died of other disease. In TD-negative group, 52 patients died of gastric cancer and 2 died of other diseases. The TD-positive group had lower 5-year survival rate than TD-negative group (31.0% vs. 52.9%,χ²=6.230, P=0.014). Subgroup analysis showed that the 5-year survival rate of T1-2 stage TD-positive patients was significantly lower than that of T1-2 stage TD-negative patients (47.1% vs. 92.6%, χ²=11.433,P<0.001),while the difference between two groups with T3-4 stage (23.8% vs. 40.0%, χ²=2.995,P=0.084)was not significant. In patients receiving chemotherapy, the 5-year survival rate of TD-positive group was significantly lower than that of TD-negative group(34.1% vs. 54.8%, χ²=4.122, P=0.042). Further subgroup analysis showed that patients receiving postoperative chemotherapy of TD-positive group both in T1-2 stage (63.6% vs. 100%, χ²=3.830,P=0.048) and in T3-4 stage (24.2% vs. 48.4%, χ²=4.740,P=0.029) had significantly lower 5-year survival rates than those of TD-negative group. However,T1-2 stage TD-positive patients receiving chemotherapy had significantly higher 5-year survival rate as compared to those without receiving chemotherapy(63.6% vs. 16.7%, χ²=5.474,P=0.019).Univariate analysis revealed T stage (HR=1.829, 95%CI:1.490-2.245, P<0.001),perineural invasion (HR=2.620, 95%CI:1.617-4.246,P<0.001),tumor size (HR=1.646, 95%CI:1.078-2.512, P=0.021),TD(HR=1.691,95%CI:1.112-2.572,P=0.014) were associated with the prognosis of patients with gastric cancer. Multivariate analysis showed TD-positive (HR=2.035, 95%CI:1.325-3.126, P=0.001), later T stage (HR=1.812, 95%CI: 1.419-2.313,P<0.001), perineural invasion (HR=1.782,95%CI:1.058-3.002,P=0.030) were independent risk factors for the prognosis of gastric cancer. CONCLUSIONS: TD is an independent risk factor for N0 stage gastric cancer,and may be closely related to T stage. Patients with TD-positive stage T1-2 should receive chemotherapy, but the prognosis of TD-positive patients undergoing adjuvant chemotherapy is poorer as compared to TD-negative patients. Therefore, more individualized treatments should be administrated.

Knockdown of lncRNA GHET1 inhibits osteosarcoma cells proliferation, invasion, migration and EMT in vitro and in vivo.

OBJECTIVE: Osteosarcoma is the most common primary malignant skeleton tumor that derives from mesenchymal cells. Emerging evidences have identified the vital role of long non-coding RNAs (lncRNAs) in the development of osteosarcoma. In this study, we aimed to investigate the role of lncRNA gastric carcinoma highly expressed transcript 1 (GHET1) in osteosarcoma progression. METHODS: The expression levels of relevant genes in clinical samples and cell lines were determined by quantitative real-time PCR. Cell proliferation was determined by CCK8 and cell colony formation assays. Transwell assay was used to detect the invasion and migration of osteosarcoma cells. Cell apoptosis and cell cycle were detected by flow cytometry. Protein levels were detected by western blot. In vivo tumor growth was investigated in the xenograft nude mice model. To determine whether growth inhibition and apoptosis are responsible for antitumor activity of silencing GHET1, immunohistochemistry for proliferation and TUNEL assay was performed in xenograft tissues. In vivo lung metastasis was performed to detect the effect of GHET1 on cell metastasis ability. RESULTS: Our results revealed that GHET1 was up-regulated in osteosarcoma tissues compared to normal tissues. GHET1 was also increased in osteosarcoma cell lines compared to normal osteoplastic cell line. The up-regulation of GHET1 was significantly associated with TNM stage, distant metastasis and lymph node metastasis in patients with osteosarcoma. In vitro studies showed that silencing GHET1 in MG-63 and U2OS cells inhibited cell proliferation, cell invasion and migration and epithelial-to-mesenchymal transition (EMT), promoted cell apoptotic rate, and also caused an increase in cell population at G0/G1 phase with a decrease in cell population at S phase. Overexpression of GHET1 promoted the proliferation, invasion and migration of osteosarcoma cells. Importantly, silencing GHET1 inhibited tumor growth and tumor metastasis in mice MG-63-xenograft model in association with changes of EMT-related genes, reduced expression of Ki-67 and promotion of apoptosis. CONCLUSION: GHET1 was up-regulated in osteosarcoma tissues and cell lines, inhibited cell apoptosis, promoted cell proliferation, invasion and migration by affecting EMT in vitro, and was correlated with the tumor growth and metastasis in vivo. GHET1 may be a potential therapeutic target of osteosarcoma treatment.

[Prognostic analysis of neoadjuvant chemotherapy for locally advanced gastric cancer with propensity score matching method].

OBJECTIVE: To compare the effects of neoadjuvant chemotherapy and adjuvant chemotherapy on the prognosis of patients with locally advanced gastric cancer using propensity score matching method. METHODS: Clinical data of patients with locally advanced gastric cancer undergoing open D2 radical gastrectomy between January 2012 and December 2014 at the Affiliated Tumor Hospital of Zhengzhou University were analyzed retrospectively. Sixty-five patients receiving neoadjuvant chemotherapy (NAC) were allocated into the NAC group and 1243 patients receiving postoperative adjuvant chemotherapy (AC) were allocated into the AC group. INCLUSION CRITERIA: (1) age ranged from 18 to 75 years old, and biopsy specimen was confirmed as adenocarcinoma; (2) all the operative procedures were open D2 radical gastrectomy;(3)image examinations showed no distant metastasis or other unresectable factors. EXCLUSION CRITERIA: no open D2 radical gastrectomy, undergoing laparoscopic surgery, neoadjuvant chemotherapy course <2 cycles, without adjuvant chemotherapy, history of other malignancies, severe complications, incomplete data. SOX (tegafur-gimeracil-oteracil plus oxaliplatin) or XELOX (capecitabine plus oxaliplatin) was used as neoadjuvant and postoperative adjuvant chemotherapy regimen. One-to-two propensity score matching was performed to balance the covariance between two groups. Survival was analyzed using the Kaplan-Meier method. Differences between the curves were tested using log-rank test. RESULTS: After balancing the covariates including gender, age, tumor location, degree of differentiation, clinical stage, chemotherapy regimen, chemotherapy course and surgical approach, 195 patients were enrolled, including 65 patients of the NAC group and 130 patients of the AC group. The number of harvested lymph nodes in NAC and AC group was 22.3±4.6 and 22.6±5.1 respectively, without statistically significant difference(t=1.125, P=0.263). Pathological response assessment for NAC group showed TRG0 in 6 cases, TRG1 in 8 cases, TRG2 in 17 cases, TRG3 in 34 cases; sensitive (TRG 0 to 2) in 31 cases (47.7%), non-sensitive in 34 cases (52.3%). The 3-year progression-free survival rate of NAC and AC group was 73.6%(95%CI: 62.8-84.3) and 69.9%(95%CI:62.1-77.7) respectively, which was not significantly different(P=0.361). The 3-year overall survival rate of NAC and AC group was 80.0%(95%CI:70.2-89.8) and 74.6%(95%CI:67.2-82.0) respectively, which was not significantly different as well(P=0.387). Subgroup analysis revealed that the 3-year progression-free survival rate and 3-year overall survival rate of sensitive patients in NAC group were 83.3%(95%CI:70.0-96.6) and 87.1%(95%CI:75.3-98.9) respectively, which were significantly higher than 62.4%(95%CI:46.1-78.7, P=0.037) and 70.2%(95%CI:54.7-85.7, P=0.033) of non-sensitive patients in NAC group, and those in AC group(P=0.044 and P=0.040). CONCLUSIONS: Effects of neoadjuvant chemotherapy and postoperative adjuvant chemotherapy on the prognosis of patients with locally advanced gastric cancer are similar. Patients who are sensitive to neoadjuvant chemotherapy have better prognosis. It may be beneficial to improve prognosis that some appropriate patients with locally advanced gastric cancer are screened for neoadjuvant chemotherapy.