Comparative analysis on morning and evening absolute dose output stability of medical linear accelerator / 医学研究生学报

Objective The ionization chamber of ELEKTA medical linear accelerator monitoring is open to environmental factors such as temperature, air pressure, and humidity that may affect the stability of absolute dose output .The article aimed to ana-lyze the morning and evening absolute dose output stability at different energies of ELEKTA SYNERGY medical linear accelerator . Methods The absolute doses at different energies of medical linear accelerators were calibrated according to the IAEA TRS -277 re-port, and WI3 type solid water was used to perform repeated measurements in the morning and in the evening for 52 consecutive days under the same measurement conditions , during which a water tank measurement was conducted at random intervals per week to verify the accuracy of WI3 solid water measurements. Results The maximum deviation of WI3 solids water and tank measurement at all en -ergies was 0.5％ and the maximum deviations of daily energy stability at different energies were : -2.0％ (6MV), 1.9％ (15MV), 1.8％ (6MeV), -2.4％ (8MeV), -2.3％ (10MeV), -2.0％ (12MeV), 2.1％ (15MeV).The differences of 6MV, 15MV, 8MeV, and 10MeV energies in morning and evening paired t tests were statistically significant (P<0.05) without clinical significance, while no statistic significance was found in the differences of 6MeV, 12MeV, and 15MeV energies ( P >0.05). Conclusion Elekta Synergy medical linear accelerator shows excellent stability in absolute dose output.

Role of the sonic hedgehog pathway in regulation of the proliferation, migration and differentiation of hemangioblast derived from AGM / 中华血液学杂志

<p><b>OBJECTIVE</b>To explore the role of sonic hedgehog (Shh) pathway in regulating the proliferation, migration and differentiation of hemangioblasts derived from aorta-gonad-mesonephros (AGM).</p><p><b>METHODS</b>The hemangioblasts were isolated from AGM region of 11-day postcoitum (dpc) murine embryos by using the immuno-magnetic with CD34 and Flk1 monoclonal antibodies. The phenotypic analysis of hemangioblasts and AGM-derived stromal cells were detected by flow cytometry. The secretion of Shh was examined by immunohistochemical staining. The roles of Shh in regulating the proliferation, migration and differentiation of hemangioblasts in the transwell non-contact coculture system with AGM-derived stromal cells were observed by adding exogenous Shh N-Terminus and its antibody.</p><p><b>RESULTS</b>The protein of Shh was highly expressed on AGM-derived stromal cells. The proliferation of hemangioblasts was promoted when co-cultured with AGM-derived stromal cells, and the effects of the latter could be blocked by antibody of Shh. The proliferation of hemangioblasts was strengthened further and kept for a long time without differentiation and apoptosis when exogenous Shh N-Terminus was added into the transwell non-contact co-culture system with AGM-derived stromal cells. When exogenous Shh N-Terminus was added into the cultural supernatant of hemangioblasts without AGM-derived stromal cells, the hemangioblasts were observed to be induced to apoptosis or differentiation after a short time of proliferation. Furthermore, the ability of migration could be promoted in the co-cultured hemangioblasts by adding exogenous Shh N-Terminus.</p><p><b>CONCLUSION</b>Shh pathway probably involves in the regulation of the proliferation, differentiation, apoptosis and migration of hemangioblasts, and is regulated by the AGM microenvironment.</p>

Inhibitory effect of murine cytomegalovirus infection on neural stem cells' differentiation and its mechanisms / 中华儿科杂志

<p><b>OBJECTIVE</b>Cytomegalovirus (CMV) is the leading infectious cause of congenital anomalies of the central nervous system caused by intrauterine infection. However, the exact pathogenesis of these brain abnormalities has not been fully elucidated. It has been reported that periependymitis, periventricular necrosis and calcification are the most frequent findings in the brains of congenital CMV infection. Because a number of multipotential neural stem cells (NSCs) have been identified from ventricular zone, it is possible that NSCs in this area are primary targets for viral infection, which seems to be primarily responsible for the generation of the brain abnormalities. Therefore, the objective of the present study was to investigate the effect and mechanism of murine cytomegalovirus (MCMV) infection on neural stem cells' differentiation in vitro and its role in the mechanisms of brain abnormalities caused by congenital cytomegalovirus infection.</p><p><b>METHODS</b>NSCs were prepared from fetal BALB/c mouse and were infected with recombinant MCMV RM461 inserted with a report gene LacZ at 1 multiplicity of infection (MOI = 1). The effect of MCMV infection on neural stem cells' differentiation was observed by detecting the ratio of nestin, GFAP and NSE positive cells with immunohistochemistry and flow cytometry on day 2 postinfection. The effects of MCMV infection on gene expression of Wnt-1 and neurogenin 1 (Ngn1) related to neural differentiation were detected by RT-PCR.</p><p><b>RESULTS</b>NSCs isolated from embryonic mouse brains strongly expressed nestin, a specific marker of NSCs and had the capacity to differentiate into NF-200 and NSE positive neurons or GFAP positive astrocytes. At MOI = 1, the results of flow cytometry assay showed that nestin positive cells' proportion in the infection group [(62.2 +/- 1.8)%] was higher than that in the normal group [(37.2 +/- 2.4)%] (t = 4.62, P < 0.01). At the same time, the rates of GFAP and NSE positive cells' in the infection group were significantly lower than those in the normal group (P < 0.01). The scanning densities of Wnt-1 was 0.14 +/- 0.03 in the infection group while 0.32 +/- 0.04 in the control group (t = 7.21, P < 0.01). The scanning densities of Ngn1 were 0.09 +/- 0.01 and 0.21 +/- 0.02 in the two groups (t = 10.7, P < 0.01).</p><p><b>CONCLUSIONS</b>These results suggest that MCMV infection could inhibit neuronal differentiation, which may be primary causes of disorders of brain development in congenital CMV infection. The decreased expression of Wnt-1 and Ngn1 may be involved in the inhibitory effect of murine cytomegalovirus infection on neural stem cells' differentiation, which may lead to a new strategy for preventing and treating brain abnormalities caused by CMV infection through regulating these two signal pathways.</p>

Expansive effects of aorta-gonad-mesonephros-derived stromal cells on hematopoietic stem cells from embryonic stem cells / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Hematopoietic stem cells (HSCs) give rise to all blood and immune cells and are used in clinical transplantation protocols to treat a wide variety of refractory diseases, but the amplification of HSCs has been difficult to achieve in vitro. In the present study, the expansive effects of aorta-gonad-mesonephros (AGM) region derived stromal cells on HSCs were explored, attempting to improve the efficiency of HSC transplantation in clinical practice.</p><p><b>METHODS</b>The murine stromal cells were isolated from the AGM region of 12 days postcoitum (dpc) murine embryos and bone marrow (BM) of 6 weeks old mice, respectively. After identification with flow cytometry and immunocytochemistry, the stromal cells were co-cultured with ESCs-derived, cytokines-induced HSCs. The maintenance and expansion of ESCs-derived HSCs were evaluated by detecting the population of CD34+ and CD34+Sca-1+ cells with flow cytometry and the blast colony-forming cells (BL-CFCs), high proliferative potential colony-forming cells (HPP-CFCs) by using semi-solid medium colonial culture. Finally, the homing and hematopoietic reconstruction abilities of HSCs were evaluated using a murine model of HSC transplantation in vivo.</p><p><b>RESULTS</b>AGM and BM-derived stromal cells were morphologically and phenotypically similar, and had the features of stromal cells. When co-cultured with AGM or BM stromal cells, more primitive progenitor cells (HPP-CFCs) could be detected in ESCs derived hematopoietic precursor cells, but BL-CFC's expansion could be detected only when co-cultured with AGM-derived stromal cells. The population of CD34+ hematopoietic stem/progenitor cells were expanded 3 times, but no significant expansion in the population of CD34+Sca-1+ cells was noted when co-cultured with BM stromal cells. While both CD34+ hematopoietic stem/progenitor cells and CD34+Sca-1+ cells were expanded 4 to 5 times respectively when co-cultured with AGM stromal cells. AGM region-derived stromal cells, like BM-derived stromal cells, could promote hematopoietic reconstruction and HSCs' homing to BM in vivo.</p><p><b>CONCLUSIONS</b>AGM-derived stromal cells in comparison with the BM-derived stromal cells could not only support the expansion of HSCs but also maintain the self-renewal and multi-lineage differentiation more effectively. They are promising in HSC transplantation.</p>

An experimental study on astrocytes promoting production of neural stem cells derived from mouse embryonic stem cells / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>The production of neural stem cells (NSCs) derived from embryonic stem (ES) cells was usually very low according to previous studies, which was a major obstacle for meeting the needs of clinical application. This study aimed at investigating whether astrocytes could promote production of NSCs derived from ES cells in vitro.</p><p><b>METHODS</b>Mouse ES cells line-D3 was used to differentiate into NSCs with astrocytes as inducing stromal cells by means of three-stage differentiation procedure. Another group without astrocytes served as control. The totipotency of ES cells was identified by observation of cells' morphology and formation of teratoma in severe combined immunodeficiency disease (SCID) mice. The quantity and purity of NSCs derived from ES cells were analyzed using clonogenic assay, immunohistochemical staining and flow cytometry assay. The plasticity of NSCs was detected by differentiating test. Octamer-binding transcription factor 4 (Oct-4) and nestin, the specific marker genes of ES cells and NSCs respectively, were detected continuously using reverse transcription-polymerase chain reaction (RT-PCR) method to monitor the process of cell differentiation.</p><p><b>RESULTS</b>The ES cells of D3 line could maintain the ability of differentiating into cellular derivations of all three primary germ layers after continuous passage culture. At the end of two-stage of inducing process, 23.2 +/- 3.5 neurospheres per plate formed in astrocyte-induced group and only 0.8 +/- 0.3 per plate in the control group (clonogenic assay, P < 0.01), and the ratio of nestin positive cells was (50.2 +/- 2.8)% in astrocyte-induced group and only (1.4 +/- 0.5)% in the control group (flow cytometry, P < 0.01). With the induction undergoing, the expression of Oct-4 gradually decreased and then disappeared, while the expression of nestin was increased step by step, and the ratio of nestin positive cells was up to 91.4% by the three-stage differentiation. The nestin positive cells could be further induced into neurons, astrocytes, and oligodendrocytes in differentiating medium supplemented with fetal calf serum. The results of differentiating test showed that the ratio of NF-200 and NSE positive cells was (42.7 +/- 2.6)% in astrocyte-induced group and only (11.2 +/- 1.8)% in the control group (P < 0.01).</p><p><b>CONCLUSIONS</b>Astrocytes can not only increase the production of NSCs derived from ES cells but also promote the differentiation of NSCs toward neuronal lineage.</p>