Objective:To explore differences in the radiation-induced intestinal injury in mice exposed to ultra-high dose rate (FLASH) and conventional-dose-rate (CONV) pulsed X-ray irradiation in order to provide evidence for the application of ultra-high dose rate pulsed X-rays in gastrointestinal radiotherapy.Methods:Using the random number table method, 32 C57BL/6J mice were randomly divided into four groups: a sham irradiation group (SHAM), two conventional dose rate groups (CONV0.067 and CONV0.1), and an ultra-high dose rate group (F215), with each group containing eight mice. All groups, except SHAM, received a single 12 Gy abdominal X-ray irradiation at dose rates of 0.067, 0.1, and 215 Gy/s, respectively. At 3 d post-irradiation, histopathological (hematoxylin-eosin staining, HE staining), immunohistochemical, and Western blot analysis were performed to assess the histopathological markers and oxidative stress indicators of intestinal tissues, as well as relevant proteins involved in signaling pathways.Results:At 3 d post-irradiation, mice in all irradiation groups suffered from varying degrees of intestinal tissue degeneration and necrosis, epithelial cell shedding, villus shortening, and crypt loss ( t = 5.75, 8.79, 5.71, P < 0.05). Regarding oxidative stress, at 3 d post-irradiation, mice in the CONV0.067 and CONV0.1 groups showed significantly lower levels of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-PX), glutathione (GSH), and total antioxidant capacity (T-AOC) compared to those in the F215 group ( t = 7.06-10.64, P < 0.01). In contrast, their malondialdehyde (MDA) levels were significantly elevated ( t = 11.06, 8.31, P < 0.01), with no statistical significance observed between them and mice in the F215 group ( P > 0.05). Immunohistochemical and Western blot analyses indicated that at 3 d post-irradiation, mice in the three irradiation groups exhibited an upward trend in the Nrf2 and HO-1 protein levels and a downward trend in the Keap1 protein level compared to those in the SHAM group. Notably, statistical significance was observed between the F215 group and the two conventional dose rate groups ( t = 4.89-20.95, P < 0.05). These result were consistent with the prior changes in antioxidant markers. Conclusions:Ultra-high-dose-rate X-ray irradiation reduces acute RIII by alleviating oxidative stress and modulating the expression of the Keap1-Nrf2-HO-1 signaling pathway.

With the rapid development and widespread application of microwave technology,people's lives and work have been made more convenient.However,the health of those who are constantly exposed to complex microwave environments is also threatened.In recent years,many studies have found that long-term exposure to micro waves can cause damage to cognitive function.However,the damage mechanism has not been fully understood.This article reviews the research progress of microwave radiation on cognitive function in recent years,the damage mechanism,and the related drugs for protection and treatment,in order to provide references for research in this field.

Objective:To explore differences in the radiation-induced intestinal injury in mice exposed to ultra-high dose rate (FLASH) and conventional-dose-rate (CONV) pulsed X-ray irradiation in order to provide evidence for the application of ultra-high dose rate pulsed X-rays in gastrointestinal radiotherapy.Methods:Using the random number table method, 32 C57BL/6J mice were randomly divided into four groups: a sham irradiation group (SHAM), two conventional dose rate groups (CONV0.067 and CONV0.1), and an ultra-high dose rate group (F215), with each group containing eight mice. All groups, except SHAM, received a single 12 Gy abdominal X-ray irradiation at dose rates of 0.067, 0.1, and 215 Gy/s, respectively. At 3 d post-irradiation, histopathological (hematoxylin-eosin staining, HE staining), immunohistochemical, and Western blot analysis were performed to assess the histopathological markers and oxidative stress indicators of intestinal tissues, as well as relevant proteins involved in signaling pathways.Results:At 3 d post-irradiation, mice in all irradiation groups suffered from varying degrees of intestinal tissue degeneration and necrosis, epithelial cell shedding, villus shortening, and crypt loss ( t = 5.75, 8.79, 5.71, P < 0.05). Regarding oxidative stress, at 3 d post-irradiation, mice in the CONV0.067 and CONV0.1 groups showed significantly lower levels of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-PX), glutathione (GSH), and total antioxidant capacity (T-AOC) compared to those in the F215 group ( t = 7.06-10.64, P < 0.01). In contrast, their malondialdehyde (MDA) levels were significantly elevated ( t = 11.06, 8.31, P < 0.01), with no statistical significance observed between them and mice in the F215 group ( P > 0.05). Immunohistochemical and Western blot analyses indicated that at 3 d post-irradiation, mice in the three irradiation groups exhibited an upward trend in the Nrf2 and HO-1 protein levels and a downward trend in the Keap1 protein level compared to those in the SHAM group. Notably, statistical significance was observed between the F215 group and the two conventional dose rate groups ( t = 4.89-20.95, P < 0.05). These result were consistent with the prior changes in antioxidant markers. Conclusions:Ultra-high-dose-rate X-ray irradiation reduces acute RIII by alleviating oxidative stress and modulating the expression of the Keap1-Nrf2-HO-1 signaling pathway.

Objective:To explore the effects of ultra-high dose rate pulsed electron beams on Caenorhabditis elegans ( C. elegans). Methods:The adult wild-type strain (N2) of C. elegans was synchronized and cultured to L4 stage, and then randomly divided into control group (SHAM group), conventional radiotherapy dose rate group (CONV group) and ultra-high dose rate radiation group (UHDR group). The CONV and UHDR groups were exposed to 3 Gy of the pulsed electron beam at dose rates of 0.3 and 200 Gy/s, respectively. After irradiation, the egg-laying capacity of each group was assessed, and the developmental progress, motility, and survival rates each were evaluated at day 3, 6, and 10. Results:On the 3 rd day post-irradiation, both the CONV and UHDR groups showed shorter body lengths compared to the SHAM group ( t=4.81, 4.83, P<0.05), with no significant differences in body width ( P>0.05). On the 6 th and 10 th days, the CONV group showed a significant reduction in both body length and width compared to the SHAM group ( t=3.18-3.63, P<0.05), whereas the UHDR group displayed a significant increase in body length ( t=-9.85, -2.87, P<0.05) with no significant change in body width. When comparing the UHDR group to the CONV group on day 6 and 10, a significant increase in body width was observed ( t=-4.43, -3.37, P<0.05). Motor activity, including head swinging and body bending, significantly decreased in the CONV and UHDR groups compared to the SHAM group on day 6 ( t=2.91, 3.52, 3.97, 2.71, P<0.05), with no significant differences among the three groups by day 10 ( P>0.05). Egg-laying capacity significantly reduced in both irradiated groups compared to the SHAM group ( t=1.72, 5.54, P<0.05), while the UHDR group exhibited higher fecundity than the CONV group ( t=-5.99, P<0.05). Lifespan was significantly shortened in the CONV group compared to the SHAM group ( χ2=8.49, P<0.05), whereas the survival time of the UHDR group was not significantly differ from that of the SHAM group ( P>0.05). Conclusions:Exposure to a conventional electron beam result in developmental delays, reduced mobility, decreased fecundity, and a shortened lifespan in C. elegans. However, only slight side effects were observed when C. elegans were exposed to an ultra-high dose rate pulsed electron beam at the same dosage.

Objective To investigate the role of Kelch-like-epichlorohydrin-associated protein 1/nuclear factor erythroid-derived factor-2-related factor 2(Keap1-Nrf2)and nuclear factor-κB(NF-κB)signaling pathways in sepsis-associated encephalopathy(SAE).Methods Male C57BL/6J mice of SPF were randomly divided into four groups(n=10):the control group and LPS 6 h,24 h and 48 h groups.The behavioral changes of the mice were assessed based on their general conditions and open field test(OFT).ELISA was used to measure the levels of pro-inflammatory cytokines in mouse serum,and the antioxidant capacity assay kit to examine antioxidant activity in brain tissues of mice.Real-time quantitative PCR(qPCR)was adopted to detect the mRNA levels of toll-like receptor4(Tlr4),NF-κB,Keap1 and Nrf2 in the hippocampus,and to determine protein expressions of NF-κB a Nrf2、Keap1 and Tlr4 with Western blotting.Results Compared to the control group,the serum concentrations of interleukin 6(IL-6)in lipopolysaccharide(LPS)groups increased at 6 h,and reached the peak at 24 h and 48 h(P＜0.01).The levels of serum interleukin 18(IL-18)in the LPS groups increased significantly at 6 h and 24 h(P＜0.01)but there was no statistically significant difference compared with the 48h group.The results indicated the activity of superoxide dismutase(SOD)and glutathione(GSH)in brain tissues in LPS groups increased(P＜0.01).OFT results showed the time spent in the center of the open field,the distance covered around the center,and total distance covered by mice in LPS groups were significantly reduced(P＜0.01),except for the time spent in the center of the open field in the LPS 24 h group.The mRNA expressions of Tlr4 and(LPS 6 h,48 h)NF-κB in the hippocampus tissue of mice in LPS groups were elevated(P＜0.05),so were the mRNA expressions of Keap1 and Nrf2 in LPS 6 h group.Additionally,the protein expressions of NF-κB,Keap1 and Tlr4 increased in LPS groups,so did the protein expression of Nrf2 in LPS 24 h and 48 h groups(P＜0.05).Conclusion Keap1-Nrf2 and NF-κB signaling pathways may play a certain role in SAE.

Objective To evaluate the characteristics of dose distribution of neuronal networks in vitro on microelectrode arrays(MEAs)under 2.6 GHz radiofrequency(RF)exposure.Methods The MEAs were coupled with a real-time RF exposure setup,and electromagnetic simulation software was used to calculate the RF dose absorbed in cultured neuronal networks.A fiber-optic temperature probe was used for experimental validation and monitoring of the cell temperature during RF exposure.The MEAs were used to record the electrical activity of neurons.Results For an input power of 1 W,a specific absorption rate(SAR)level of(15.51±2.48)W/kg was calculated,and the variability of the SAR distribution was 16%.In our experimental system,the temperature elevation of neurons was up to 0.15℃for an SAR of 4 W/kg RF exposure.Conclusion The exposure device can provide high SAR efficiency and uniformity in the 2.6 GHz band,which is suitable for studying the real-time effects of RF fields on the electrical activity of neuronal networks in the 5G network band.

Objective:To analyze the damage in hippocampal tissues of mice after whole-body irradiation with high- or low-dose ionizing radiation and to investigate the roles of microglia/macrophages polarization in the injury.Methods:C57BL/6 mice were randomly divided into three groups: sham irradiation group, low-dose group (0.05 Gy) and high-dose group (7 Gy). Low- and high-dose groups were respectively treated by whole-body irradiation with single dose of 60Co γ-rays. Hippocampal tissues of the mice were collected at 6 h, 1 d, 3 d and 7 d after irradiation. The morphology, structure and apoptosis of neurons were detected by HE staining, Nissl staining and Tunnel staining, respectively. RT-PCR and immunofluorescence assay were performed to detect the expression of M1 and M2 microglial markers at mRNA and protein levels in hippocampus tissues. The cognitive and emotional behaviors of mice were evaluated one month after the irradiation by Morris water maze, open field test, elevated plus maze and tail suspension test. Results:There were morphological and structural changes in the nerve cells in the hippocampus region of mice after irradiation, accompanied by apoptosis. Acute injuries occurred at 6 h after radiation, alleviated at 1 d and 3 d, and persisted at 7 d in a dose-dependent manner. The results of immunofluorescence staining and confocal imaging analysis showed that compared with the sham irradiation group, the high-dose group showed increased number of microglia, down-regulated expression of M1 microglial markers and up-regulated expression of M2 microglial markers in the hippocampus at 6 h and 1 d after radiation, while M2 microglial markers decreased at 3 d and 7 d after irradiation. PCR results showed that the expression of M1 and M2 microglial markers at mRNA level in the irradiation groups increased at 6 h after irradiation, but there was no statistical significance. The expression of related proinflammatory/anti-inflammatory factors was significantly up-regulated. The results of behavioral experiments showed that compared with the sham irradiation group, there was no statistical difference in cognitive or emotional behaviors at one month after irradiation.Conclusions:60Co γ-rays could damage mouse hippocampal tissues and result in the overexpression and different polarization patterns of microglia/macrophages in mice.

Objective:To investigate the application of therapeutic grade ionization chamber to rapid measurement of short pulsed and high-dose-rate X-ray.Methods:The half-value layer of pulsed X-ray caused by an electron accelerator was measured by interpolation method and its equivalent energy was estimated. The cumulative doses from a certain amount of pulsed radiation at different distances in the same direction around the equipment were compared using the therapeutic grade ionization chamber and thermoluminescence measurement method . The relationship between the measurement result by using ionization chamber dosimeter and the distances away from source was analyzed. The cumulative doses from a certain amount of pulsed radiation at the same location at different frequencies were compared.Results:In working condition, 100 pulses of radiation were received accumulatively at 1 to 12 meters away from the outer wall of the equipment. The range of air Kerma was 0.08-9.65 mGy measured by using thermoluminescence dometers and 0.08 - 9.85 mGy using the ionization chamber dosimeters, respectively. The difference between both is within 10%. At different frequencies (1-10 Hz), there was no significant difference in X-ray air Kerma from 100 pulses measured by ionization chamber dosimeter at 2 m away from the front of the equipment ( P>0.05). Conclusions:The therapeutic grade ionization chamber dosimeter can be used for the rapid measurement of short pulsed X-ray radiation dose in the range of dose rates and pulse frequencies involved in the experimental accelerator device.

Objective:To construct a prokaryotic expression vector for liver and lymph node sinusoidal endothelial cell C-type lectin carbohydrate recognition domain (LSECtin-CRD) in which two amino acids were mutated to Cys and to evaluate the bioactivity of LSECtin-CRD mutants.Methods:Mutation sites were selected based on predicted 3D model of LSECtin-CRD. Site-directed mutagenesis was carried out using sequence overlapped extension PCR (SOE-PCR). The cDNA fragments of LSECtin-CRD mutants were subcloned into the prokaryotic expression vector pET28b-Tat. The expression of soluble LSECtin-CRD mutants was induced with IPTG and identified by SDS-PAGE. Ni-NTA affinity chromatography was used for purification. The bioactivities of LSECtin-CRD mutants were assessed by mannose and GlcNAc binding assays.Results:The prokaryotic expression vectors for LSECtin-CRD mutants G205C-A227C and G205C-D279C were successfully constructed as demonstrated by PCR and gene sequencing. The two mutants were efficiently expressed in soluble forms and had significant sugar-binding activities.Conclusions:Functional LSECtin-CRD mutants were successfully obtained, laying an experimental foundation for further study on the relationship between the function and structure of LSECtin-CRD.

Objective To explore the feasibility of EPR in vivo fingernail dosimetry to address the difficulty in separating mechanically induced signals from fingernail EPR dosimetry for need of nuclear medical emergency aid.Methods Using the specially designed EPR in vivo measurement system,uncut fingernails were measured to obtain the characteristics of EPR signal without mechanically induced signals.The in vivo fingernail experiment was carried out to evaluate the impact of in vivo condition on the spectra.Actual in vivo measurement experiment was conducted to evaluate the interference of the in vivo condition on EPR spectra.Results The background signal distribution of uncut fingernails was obtained and background signals had no significant difference between male and female(P＞0.05).The dose response curve in the range of 2-10 Gy was established,and the half-life of the fingernail radiation-induced signal was approximately 5 d.The water treatment combined with temperature-changing was established for restoring the background signal.EPR signal obtained after restoring treatment has no significant difference with background signal (P＞ 0.05).The EPR spectra of in vivo fingernails were obtained.Conclusions The EPR spectra without mechanically induced signals can be acquired by this method.The feasibility of the in vivo fingernail EPR dosimetry is preliminarily verified.