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Objective:To investigate the protective effect of intermittent fasting on radiation-induced cognitive impairment and the possible underlying mechanism.Methods:A total of 36 male 7-week old c57BL/6J mice were divided into Sham-irradiation and ad libitum (Sham-AL) group, irradiation and ad libitum (IR-AL) group, and irradiation add intermittent fasting (IR-IF) group according to the random number table method, with 12 mice in each group. The cognitive function of mice was assessed by novel object recognition task. The expressions of autophagy gene 5 (ATG5), microtubulesas sociated protein light chain II (LC3II), voltage dependent anion channel protein 1 (VDAC1), interleukin-1β (IL-1β), synaptophysin (SYP), synapsin I (SYN-1), and postsynaptic density 95 (PSD95) were tested by Western blot. The location of VDAC1 in mice hippocampus was detected by immunofluorescence.Results:The discrimination index (-22.45 ± 16.76) of IR-AL group was significantly ( t=3.032, P<0.05) lower than that of Sham-AL group (30.02 ± 9.05). Compared to Sham-AL group, IR-AL group had a decreased expressions of autophagy-related proteins (ATG5 and LC3II), mitochondrial marker (VDAC1), inflammatory factors (IL-1β) as well as synapse-associated proteins SYP, SYN-1 and PSD95 ( t=2.49, 2.19, 2.40, 3.47, 2.87, 2.25, 2.17, 2.31, P<0.05). Compared to IR-AL group, IR-IF group had an increased discrimination index (21.22 ± 5.62) and the increased expressions of ATG5, LC3II, VDAC1, IL-1β, SYP, SYN-1, and PSD95 ( t=2.70, 2.88, 2.71, 3.18, 3.18, 3.11, 3.30, 3.35, 2.53, P<0.05). The immunofluorescence assay revealed that VDAC1 was co-expressed with the markers of astrocytes (GFAP) and microglia (IBA-1), but not with neurons (NEUN). Conclusions:Intermittent fasting could greatly improve the cognitive function of irradiated mice possibly by upregulating VDAC1 expression, induce autophagy, and inhibit the release of inflammatory factors and protecting the synapticplasticity in the hippocampus.
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Objective:To investigate the effect of MCC950 (a NLRP3 inflammasome inhibitor) on cognitive impairment in mice with radiation-induced inflammatory brain injury.Methods:Mice were divided into normal (NS) group, whole body irradiation (IR) group and MCC950 intervention post irradiation (IR+ MCC950) group according to the random number table method, with 15 mice in each group. The mice in IR group and IR+ MCC950 group were irradiated with a single dose of 4.0 Gy. The radiation source was 137Cs and the dose rate was 1.118 Gy/min. The mice in NS group were not irradiated. Mice in IR+ MCC950 group were injected intraperitoneally with MCC950 once a day (10 mg/kg each time) from 3 weeks after irradiation. Behavioral tests such as new and old things recognition experiment and social cognition experiment were used to detect the cognitive function of mice. Immunohistochemistry was used to detect the expression of NeuN protein in CA3 area of mouse hippocampus. PCR and Western blot were used to detect the expression of NLRP3 inflammatory body related protein. Results:Compared with NS group, the short-term and long-term recognition index of new and old things in the IR group decreased significantly ( t=4.321, 5.473, P<0.01), and the social cognitive recognition index of the IR group also decreased significantly ( t=2.097, P<0.05). MCC950 treatment reversed the above changes (short-term and long-term new and old thing recognition test: t=5.860, 4.598, P<0.05; new and old position recognition test: t=3.040, P<0.05; social cognition test: t=4.021, P<0.01). The expression of NLRP3, Caspase-1, IL-1 β and IL-18 in mice hippocampus of the IR group was significantly higher than that of the control group ( t=2.699, 8.515, 3.340, 3.950, P<0.05). Compared with NS mice, radiation significantly increased the expressions of Bax, Caspase-3 and PARP1 in hippocampus ( t=3.887, 2.742, 3.287, P<0.05), while MCC950 significantly decreased the expressions of Bax, Caspase-3 and PARP1( t=2.852, 4.090, 9.614, P<0.05). Conclusions:NLRP3 inflammasome inhibitor MCC950 could alleviate radiation-induced cognitive impairment, which may be due to the inhibition of hippocampal inflammatory and neuronal death.
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Objective To investigate the protective effect and mechanism of environmental enrichment(EE)on radiation induced cognitive dysfunction in mice.Methods A total of 45 female Kunming mice(2-month old)were randomly divided into control group,irradiation group and irradiation plus EE group with 15 in each group.Irradiation group and irradiation plus EE group were treated with a single dose of 4 Gy whole body irradiation,irradiation plus EE group were housed in EE condition for 35 d after irradiation.The object recognition task was used to evaluate the cognitive function of mice.The expression of microglial marker IBA-1 in hippocampus was determined by immunohistochemical staining.The expressions of CD68 and synaptophysin(SYP)proteins in hippocampus were assayed by Western blot.Results Compared with control group,the irradiation group had a low discrimination ratio in object recognition task and had a remarkable low level of SYP expression in hippocampus(t＝3.66,6.84,P＜0.05).In addition,radiation activated microglia in hippocampus by increasing the number of IBA-1-positive cells and enhancing the expression of CD 68(t ＝6.83,5.79,P ＜0.05).Compared with irradiation group,irradiation plus EE group increased the discrimination ratio and the expression of SYP in hippocampus(t＝3.56,4.06,P＜0.05),while the number of IBA-1-positive cells and the expression of CD68 were significantly reduced(t＝7.69,4.59,P＜0.05).Conclusions A single dose of 4 Gy whole body irradiation leads to cognitive dysfunction in mice,while EE could effectively improve the animals′cognitive behavior possibly by inhibiting microglial activation and preventing synapse loss in hippocampus.
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Objective To determine the optimal electron beam energy at different field size through a Monte Carlo-based simulation of the therapy head of Varian X 6 MV linear accelerator so as to study the influence of radial intensity on depth dose.Methods Firstly,keeping the radial intensity unchanged for the field of interest while changing electron beam energy,compassion was carried out of calculated percentage depth doses between measured values.Thus,the optimal energy was identified for this field size.Then,the obtained energy was set the optimal value to study the radial intensity influence on the depth doses.Results The optimal electron energy for 4 cm ×4 cm,10 cm × 10 cm,20 cm × 20 cm and 30 cm × 30 cm field sizes was 5.9,6.0,6.3 and 6.4 MeV respectively.Changes in radial intensities resulted in negligible changes in percentage depth doses for4 cm ×4-cm and 10 cm × 10 cm fields,but led to observable discrepancy for 20 cm × 20 cm and 30 cm × 30 cm fields.Conclusions The optimal electron energies for different field sizes are slightly different.Change in radial intensity distribution has significant influence on the depth dose for large field.To improve simulation accuracy,the field size needs to be taken into consideration in determining the electron beam energy and radial intensity distribution.
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Objective To retrospectively analyze the prognostic factors for locoregionally recurrent early?stage extranodal nasal?type natural killer/T?cell lymphoma ( NKTCL) . Methods A total of 56 patients with early?stage extranodal nasal?type NKTCL, who had locoregional recurrence after initial treatment and then received salvage treatment from 1995 to 2014, were enrolled as subjects. The effects of salvage treatment on the overall survival ( OS) rate were analyzed after initial treatment and recurrence. Univariate and multivariate prognostic analyses were performed on the OS rate after recurrence. Results The median follow?up time was 35. 9 months after initial treatment and 14. 8 months after recurrence. The 3?year OS rate was 73% after initial treatment and 58% after recurrence. Compared with chemotherapy alone, radiotherapy?containing salvage treatment significantly improved the OS rates after initial treatment and recurrence ( P=0. 040, 0. 009 ) , and re?irradiation also significantly improved the OS rates after initial treatment and recurrence (P=0. 018, 0. 019). Most (84%) of the acute and late adverse reactions after re?irradiation were grade 1?2 ones. The univariate and multivariate analyses showed that the Karnofsky Performance Status score, radiotherapy in initial treatment, and radiotherapy in salvage treatment were influencing factors for the OS rate after recurrence. Conclusions Radiotherapy achieves improved survival and tolerable toxicities, making it indispensable in the treatment of locoregionally recurrent extranodal nasal?type NKTCL.