CeO / 中国生物化学与分子生物学报

Drought is a common limiting factor affecting rice yield and quality. Cerium oxide nanoparticles(nanoceria) have been widely reported to improve crop stress tolerance. However, the effects and mechanisms of nanoceria on rice drought tolerance are still unknown. The aim of this study is to investigate whether nanoceria can improve rice drought tolerance by modulating reactive oxygen species(ROS) homeostasis and nitric oxide(NO) levels. Our results showed that compared with no-nanoparticle treatment, nanoceria significantly increased the fresh weight of rice seedlings under drought stress(19%, P < 0. 05). Also, under drought stress, the ROS level of rice leaves treated with nanoceria was significantly lower(82%, P < 0. 05) than leaves treated with buffer. The leaf NO level after nanoceria treatment, however, is significantly higher(46%, P < 0. 05) than that with no-nanoparticle treatment under drought stress. Moreover, compared with control plants, nanoceria maintained better membrane integrity in rice leaf cells under drought stress, showing a 70% decrease(P < 0. 05) in dead leaf cells. This study explores the mechanisms underlying nanoceria’s improved rice drought tolerance by affecting ROS and NO levels, which not only further enriches our knowledge about the interaction between nanoparticles and crops under abiotic stress but also gives more support on the sustainable development of nano-enabled agriculture.

Prognostic significance of minimal residual disease detected by multiparameter flow cytometry in acute myeloid leukemia / 中国实验血液学杂志

This study was aimed to explore prognostic significance of minimal residual disease (MRD) detection in patients with acute myeloid leukemia (AML) by multiparameter flow cytometry (MCF). Leukemia-associated immunophenotype (LAIP) of newly diagnosed AML patients were determined by 4-color 5 antibody panels and patients with sensitive LAIP were chosen for MRD detection. 601 bone marrow samples from 95 patients were acquired after treatment and MRD were considered positive by the critical normal value plus twice standard deviation in normal bone marrow specimen. The patients were divided into three groups and the clinical significance was analyzed every 2 months within initial 6 months after induction treatment. The results showed that the relapse rate and relapse-free survival (RFS) rate were all significantly different between MRD positive and MRD negative patients in the three groups (p < 0.05). Patients with MRD positive had a median relapse-free survival time of 11 months, 11.5 months and 11 months at 1 - 2, 3 - 4 and 5 - 6 months respectively, while all patients with MRD negative were not observed to reach median release-free survival time (p < 0.05). Furthermore, the clinical significance was analyzed after induction and one course of consolidate treatment, the relapse rate of MRD positive and MRD negative patients were 57.14% versus 0% and 91.67% versus 2.27% respectively (p = 0.000 and p = 0.000). It is concluded that MRD detection by multi-parameter flow cytometry can predict outcome of AML patients, which should be continuously monitored after treatment.

Expression of 5 genes in CD7 positive acute myeloid leukemia stem/progenitor cells from bone marrow / 中国实验血液学杂志

This study was aimed to investigate abca5, mdr-1, kdr, dapk and irf-1 expressions in leukemia stem/progenitor cells (LSC) from CD7 positive acute myeloid leukemia, the expression of these 5 genes in mononuclear cells (MNC) from 15 normal bone marrow (NBM) and 16 AML patients bone marrow (AML BM) specimen were detected by real-time quantitative PCR (RQ-PCR). CD34(+)CD38(+) progenitor cells and CD34(+)CD38(-)Lin(-) stem cells were sorted by flow cytometry (FCM) from the MNCs of 10 NBM and 21 AML BM specimen. These 5 gene expressions in the sorted cells were detected by small amount cell RQ-PCR. The results showed that these 5 genes above mentioned all expressed in NBM-MNC, in which the expression levels of irf-1 and dapk were highest with the relative expression levels 4.08 and 3.86, the expression levels of abca 5 and mdr-1 were in the middle with the relative expression 0.49 and 0.84 respectively, the kdr expression was lowest with the relative expression level 0.02. In CD34(+)CD38(+) progenitor cells, the expression level of kdr increased dramatically (p < 0.05) while irf-1 and dapk dramatically decreased (p < 0.05). There was no obvious change of expression in the rest 2 genes. In CD34(+)CD38(-) stem cells the expression level of these 5 genes all increased nearly 2 times as much as that in CD34(+)CD38(+) progenitor cells, but kdr increased 3 times as much, and the increase of kdr and irf-1 expressions was of statistical significance (p < 0.05). Compared with the NBM, expression levels of 5 genes in AML-MNC decreased, and out of them abca 5, mdr-1, kdr and dapk were decreased most remarkably (p < 0.05). Comparison between AML CD34(+)CD38(+) cells and AML MNC showed that the expression level of irf-1 and dapk were decreased dramatically (p < 0.05) while the rest 3 genes increased their expression with statistical significance (p < 0.05). The expression levels of these 5 genes were higher in CD34(+)CD38(-) cells than those in CD34(+)CD38(+) stem cells, and the increase of kdr and irf-1 expressions showed statistical difference (p < 0.05). These 5 genes expression levels were all higher than those in CD34(+)CD38(+) cells whether in AML CD34(+)CD38(-)CD7(+) cells or CD34(+)CD38(-)CD7(-) cells. The increase of kdr expression in CD34(+)CD38(-)CD7(+) cells as well as kdr and irf-1 expressions in CD34(+)CD38(-)CD7(-) cells were all of statistical significance (p < 0.05). In conclusion the expression level of kdr in NBM was highest in stem cells while dapk and irf-1 were highest in differentiated cells. The expression levels of these 5 genes in CD34(+)CD38(-)Lin(-) stem cells were higher than those in CD34(+)CD38(+) progenitor cells. The gene expressions in AML CD34(+)CD38(-)CD7(+) cells and CD34(+)CD38(-)CD7(-) cells are in accordance with the characteristics of stem cells.

The immunophenotypic analysis of CD7+ and (or) CD56+ acute myeloid leukemic stem cells and its applications in minimal residual disease detection / 中华血液学杂志

<p><b>OBJECTIVE</b>To explore the immunophenotypic characteristics of CD7 and/or CD56 positive acute myeloid leukemic stem cells, and the relationship between minimal residual disease (MRD) and the leukemic stem cells (LSC).</p><p><b>METHODS</b>The immunophenotype of leukemia cells from 51 CD34+ CD38+ CD7+ and/or CD34+ CD38+ CD56+ acute myeloid leukemia (AML) patients (exclude M3) at diagnosis was analyzed by using 4 - 6 panels of 4 color antibodies, and cells from 28 normal bone marrow (NBM) samples were served as control. The expression of CD7 and CD56 in the CD34+ CD38+ subpopulation was used as a leukemic cell marker for monitoring MRD of 53 samples from 26 CD7+ and (or) CD56+ patients.</p><p><b>RESULTS</b>In CD7+ and/or CD56+ AML patients at diagnosis, the average positivity of CD7 in CD34+ CD38+ subpopulation and CD34+ CD38- Lin- stem cells subpopulation was (77.39 +/- 20.71)% and (44.57 +/- 22.70)%, and that of CD56 was (56.71 +/- 32.56)% and (33.51 +/- 29.64)%, respectively, all significantly higher than that of NBM (P < 0.01 and P < 0.05). Compared with that of NBM, the expression of CD90 in AML patients was significantly lower in the CD34+ CD38- Lin- subpopulation (P < 0.01), the expression of CD123 was significantly higher than NBM (P < 0.01), and the expression of CD117 was no significant difference (P > 0.05). In follow up of CD7+ and (or) CD56+ patients, the expression rate of CD7 and (or) CD56 in the CD34+ CD38- Lin- subpopulation MRD+ group was significantly higher than that in the MRD- group. The actual rate for CD7 was 71% (15/21) and 16% (4/25) (P = 0.001), and its relative rate was 81% (17/ 21) and 24% (6/25) (P = 0.000), respectively. The actual rate of CD56 is 100% (4/4) and 12% (3/25) (P = 0.001), and its relative rate was 75% (3/4) and 20% (5/25) (P = 0.031), respectively. A high CD7+ CD34+ CD38- Lin- subpopulation frequency at diagnosis in CD7+ AML patients predicted a high frequency of positive MRD in later detection (P < 0.05).</p><p><b>CONCLUSIONS</b>CD7 and CD56 are expressed on the stem cells in CD7+ and/or CD56+ AMLs and a high frequency of CD7 and CD56 in the CD34+ CD38- Lin- stem cell subpopulation predicts a high frequency of positive MRD in later detection.</p>