Binding modes of GDP, GTP and GNP to NRAS deciphered by using Gaussian accelerated molecular dynamics simulations.

Probing binding modes of GDP, GTP and GNP to NRAS are of significance for understanding the regulation mechanism on the activity of RAS proteins. Four separate Gaussian accelerated molecular dynamics (GaMD) simulations were performed on the apo, GDP-, GTP- and GNP-bound NRAS. Dynamics analyses suggest that binding of three ligands highly affects conformational states of the switch domains from NRAS, which disturbs binding of NRAS to its effectors. The analyses of free energy landscapes (FELs) indicate that binding of GDP, GTP and GNP induces more energetic states of NRAS compared to the apo NRAS but the presence of GNP makes the switch domains more ordered than binding of GDP and GNP. The information of interaction networks of ligands with NRAS reveals that the π-π interaction of residue F28 and the salt bridge interactions of K16 and D119 with ligands stabilize binding of GDP, GTP and GNP to NRAS. Meanwhile magnesium ion plays a bridge role in interactions of ligands with NRAS, which is favourable for associations of GDP, GTP and GNP with NRAS. This work is expected to provide useful information for deeply understanding the function and activity of NRAS.

[Current status of HIV self-testing application].

HIV self-testing is a key measure and strategy to expand the coverage of HIV testing in key populations, which has great value in application and high acceptance in key populations. The World Health Organization (WHO) issued the Guidelines on HIV self-testing and partner notification in 2016 to support the application of HIV self-testing and provide specific guidance for countries and organizations to develop corresponding public health policies for the purpose of improving the accessibility and utilization of HIV diagnostics. HIV self-testing has been promoted in many countries and has achieved great results. This article provides an overview of the current domestic and international HIV self-testing policies, intervention models, the use of self-testing kits, the accuracy of self-testing kits, and the application of pre- and post-testing counseling services to provide reference for the further improvement of HIV self-testing in China.

[Clinical significance of S100A6 and Notch1 in multiple myeloma patients].

Objective: To investigate the expression levels of S100A6, Notch1 in multiple myeloma (MM) patients and its clinical significance. Mathods: The expression levels of S100A6, Notch1 in 28 MM cases and 20 healthy controls were determined by real time quantitative PCR (RQ-PCR) , and their relationships with clinical features and outcomes were analyzed. Immunohistochemical was used to analysis the levels of S100A6 and Notch1 in bone marrow biopsy samples and intramedullary metastases soft tissues. RQ-PCR and Western blot were used to test the changes of Notch1 mRNA and Notch1 protein in U266 MM cells after S100A6 silenced by siRNA. Results: ①The expression levels of S100A6, Notch1 in primary MM patients was 2.19±1.25, 2.98±0.64, significantly higher than those in controls (0.71±0.20, 0.58±0.39, P<0.05) and patients in platform status (0.85±0.26, 0.72±0.40, P<0.05) . 8 cases with intramedullary metastasis had significantly higher levels of S100A6 (3.36±1.23) and Notch1 (5.71±3.96) , as compared to those without extra medullary metastases. ②S100A6 expression was positive correlation with Notch1 (r=0.505, P=0.007) . ③S100A6 and Notch1 proteins were positive in plasma cells of bone marrow biopsy samples and intramedullary metastases soft tissues. ④The Notch1 mRNA and Notch1 expression decreased significantly after 48 hours treatment by S100A6 siRNA in U266 cells. Conclusion: S100A6 and Notch1 were closely associated with MM progress and intramedullary metastasis. They have significant correlation and might be as two prognostic molecular markers in MM.

Phase II trial of a 2-h infusion of gemcitabine plus carboplatin as first-line chemotherapy for advanced non-small-cell lung cancer.

PURPOSE: To evaluate the efficacy and safety of the combination of using gemcitabine as a rate infusion of 10 mg/m(2) per min with carboplatin in front-line chemonaive patients with advanced non-small-cell lung cancer (NSCLC). PATIENTS AND METHODS: Fifty-four chemonaive patients with stage IIIB or IV NSCLC have been included, 44 males and 10 females, with a median age 63 years (range 19-75). Thirty-two (59%) patients had adenocarcinoma, 13 (24%) squamous cell, 1 (2%) large cell carcinoma and 8 (15%) others. Eight (15%) had stage IIIB and 46 (85%) stage IV. Treatment was consisted of 1,200 mg/m(2) gemcitabine given as a 2-h continuous infusion (10 mg/m(2) per min) on days 1 and 8 of each cycle an AUC 5 carboplatin as on day 1, repeating each cycle for every 21 days. A total of 223 chemotherapy cycles were administered, with a median of four cycles per patient (range 1-6), and 15 (28%) patients received all six cycles. RESULTS: Of the 54 patients enrolled, all were evaluated for toxicity and 51 assessed for response. The overall response rate was 41% (95% confidence interval, 28-57%) with complete and partial responses of 4 and 37%, respectively. The median time to disease progression was 5.0 months (95% CI, 3.7-6.3 months), and median overall survival time was 11.5 months (95% CI, 9.9-13.1 months). One-year survival was 42%. The main grade 3-4 toxicity (according to the WHO scale) consisted of neutropenia (56%) and thrombocytopenia (57%). Patients were required platelet transfusion in 27 cycles (12%) and hematopoietic growth factors support care in 56 (25%) cycles. No bleeding episodes were recorded. Grade 3 nausea/vomiting occurred in 6% and grade 1-2 skin rash occurred in 43%. CONCLUSIONS: Prolonged gemcitabine infusion combined with carboplatin is manageable and tolerated, and its efficacy is similar to that of other chemotherapeutic schemes used for NSCLC treatment.