Establishment of a Stable Cell Line Overexpressing Human SAMHD1 Gene and Its Antiviral Activity / 中国医科大学学报

Objective A lentivirus-mediated colon cancer cell line stably overexpressing human SAMHD1 gene was constructed to observe the effect of this gene on the ability of the cells to resist herpes simplex virus type 1 (HSV-1) infection. Methods p CDH-EF1-MCS-SAMHD1-T2 A-GFP recombinant plasmid was constructed using pCDH-EF1-MCS-T2 A-copGFP lentiviral vector. After confirming successful synthesis with sequencing, the recombinant plasmid and lentivirus packaging plasmids were co-transfected into 293 T cells. The pseudovirus solution was collected and concentrated, then human colon cancer cells were infected with the concentrated solution. The cell line overexpressing SAMHD1 gene was infected with HSV-1 in contrast to the control group, and the virus infection efficiency was assessed by Western blotting and immunofluorescence analyses. Results The pCDH-EF1-MCS-SAMHD1-T2 A-GFP recombinant plasmid was successfully constructed and verified by gene sequencing. Western blotting confirmed the overexpression of the SAMHD1 gene with higher levels of the gene in the transfected cells in contrast to control human colon cancer cell line. Western blotting and immunofluorescence showed that the cell line overexpressing human SAMHD1 gene could effectively inhibit the infection of HSV-1. Conclusion Lentivirus-mediated stable cell line overexpressing human SAMHD1 gene was effective in inhibiting HSV-1 replication and could help us to further investigate the function of SAMHD1.

Neuroprotective Autophagic Flux Induced by Hyperbaric Oxygen Preconditioning is Mediated by Cystatin C / 神经科学通报·英文版

We have previously reported that Cystatin C (CysC) is a pivotal mediator in the neuroprotection induced by hyperbaric oxygen (HBO) preconditioning; however, the underlying mechanism and how CysC changes after stroke are not clear. In the present study, we demonstrated that CysC expression was elevated as early as 3 h after reperfusion, and this was further enhanced by HBO preconditioning. Concurrently, LC3-II and Beclin-1, two positive-markers for autophagy induction, exhibited increases similar to CysC, while knockdown of CysC blocked these elevations. As a marker of autophagy inhibition, p62 was downregulated by HBO preconditioning and this was blocked by CysC knockdown. Besides, the beneficial effects of preserving lysosomal membrane integrity and enhancing autolysosome formation induced by HBO preconditioning were abolished in CysC rats. Furthermore, we demonstrated that exogenous CysC reduced the neurological deficits and infarct volume after brain ischemic injury, while 3-methyladenine partially reversed this neuroprotection. In the present study, we showed that CysC is biochemically and morphologically essential for promoting autophagic flux, and highlighted the translational potential of HBO preconditioning and CysC for stroke treatment.

Commissioning of intensity - modulated radiation therapy system with independent collimator / 中华放射肿瘤学杂志

Objective To perform an acceptance test for the IMRT system with independent collimator. Methods An ion chamber dosimeter were used to measure the startup characteristics of the accelerator and the absolute dose at isocenter and given characteristic points for three clinical cases ( a lower nasopharyngeal carcinoma, a lung cancer and a cervical cancer). The characteristic points represented the organs at risk or the target. A Mapeheck2 was used to measure dose maps of basic test fields and the treatment fields for the clinical cases. The basic test fields were as follows: 1 ). Symmetric fields in size of 2 cm ×2 cm, 5 cm ×5 cm, 10 cm× 10 cm, 20 cm ×20 cm, 2 cm × 10 cm, 10 cm ×2 cm, 5 cm ×20 cm and 20 cm ×5 cm;2). Asymmetric fields in size of 2 cm ×2 cm (x1 =4 cm, y1 = 10 cm;x2 = -2 cm, y2 = -8cm) and 5 cm ×5 cm (x1 = -2 cm, y1 = -5 cm;x2 =7 cm, y2 = 10 cm) ;3) A 20 cm ×20 cm composite field composed of five 20 cm× 4 cm narrow bar fields side by side. Gamma Index was used to compare calculated and corresponding measured dose distributions. When the criterion was 3% dose difference or 3 mm distance-to-agreement, the pass rate was required to be more than 90%. Results The accuracy of machine output was better than 2% when machine monitor units increased to 4. Among all basic test fields and all the treatment fields of three clinical cases, the maximal absolute dose error was -3.67%, and only the composite test field and two treatment fields of the lower nasopharyngeal carcinoma case had a pass rate slightly less than 90%, which were 83.6%, 88. 3% and 89. 7% ,respectively. For the three clinical cases the treatment delivery times were 15, 14, and 27 minutes, respectively. Conclusions The overall commissioning results are acceptable, and the system can be used in clinic.