Tumor vaccine is one of the most promising therapeutic strategies in tumor immunotherapy. It promotes the antigen presentation process by delivering tumor antigen and then activates the anti-tumor immune response. As a new class of vaccines, messenger RNA (mRNA) vaccines can activate the immune system to achieve the purpose of immunotherapy by delivering the mRNA sequence of a specific antigen into the body and expressing the corresponding antigen protein. Compared with traditional vaccines, mRNA vaccines have the advantages of a short production cycle, high effectiveness, and strong immunogenicity. In recent years, the application of mRNA vaccines in tumor immunotherapy has attracted widespread attention, but the instability and low delivery efficiency of mRNA limit its application. Nano delivery system can effectively solve the problem of mRNA vaccine delivery, greatly promote the research process and clinical application of mRNA tumor vaccines, and has become a hot spot in the research of mRNA vaccines. In this review, we introduced the mRNA tumor vaccines, focusing on the application of nano delivery system in mRNA tumor vaccines, in order to provide new ideas and new methods for the efficient delivery of mRNA tumor vaccines and tumor immunotherapy.

Objectives: To explore the influence of exercise training on the arterial baroreflex sensitivity （BRS）and correlation between blood pressure and BRS in spontaneously hypertensive rats (SHR). Methods: Male SHR（n=20）and normotensive Wistar rats（n=20）were randomly assigned to normality group and exercise group, n=10 in each group. Rats in two exercise groups received treadmill training at a speed of 20 m/min for 60 min/d, 6 d/w for eight weeks. Systolic blood pressure (SBP) and heart rate (HR) were measured using a tail-cuff method in a conscious state. Intravenous injections of phenylephrine (PE) and sodium nitroprusside (NP) were used to induce depressor and pressor reflex respectively. The ratio of HR over mean arterial pressure (MAP) (HR /MAP) after administration of PE or NP was regarded as an index of depressor reflex sensitivity (BRS-PE) and pressor reflex sensivity (BRS-NP). Results: After eight-week exercise training, compared with SHR normality group, there were significant reduction in resting SBP [(180±8.5) mmHg vs. (163.6±10.7) mmHg] and in HR [(368.4±13.3) beats/min vs. (345.0±9.8) beats/min] in SHR exercise group, P<0.01 both. However, there was no significant difference in resting SBP between Wistar exercise and normality groups (P>0.05), compared with Wistar normality group, there was significant reduction in HR [(362.2 ± 13.0) beats/min vs. (343.9 ± 10.2) beats/min, P <0.05] in Wistar exercise group. Compared with SHR normality group, there were significant rise in BRS [BRS-PE: (0.89 ± 0.13) bpm/mmHg vs. (1.32 ± 0.22) bpm/mmHg, BRS-NP： (0.60± 0.09) bpm/mmHg vs. (1.21± 0.26) bpm/mmHg, P<0.01] in SHR exercise group, but still lower than those of Wistar normality group [BRS-PE: (1.96±0.23) bpm/mmHg, BRS-NP: (1.32±0.17) bpm/mmHg]. Pearson linear correlation analysis indicated that MAP was significantly inversely correlated with BRS (r=-0.734, P<0.01) in SHR normality and exercise group. Conclusion: Exercise training may significantly decrease SHR blood pressure; it is related to improved baroreflex sensitivity induced by exercise, indicating that enhanced baroreflex may be an important mechanism of exercise therapy in hypertensive patients.

Objective To study the relationship between static duration and bacteria reproduction of pure water from the RO purifier. Methods The original structure of RO purifier was modified by installing additional UV lights and ozone disinfector respectively. Bacteria reproduction in the effluent from RO purifier and modified RO purifier was detected after different static duration. Results The total count of bacteria in the fresh pure water was 20 cfu/ml which was up to the standard of pure drinking water CJ 94-1999. However the total count of bacteria in the pure water will be more than 50 cfu/ml after the pure water was stored inside the tank for six hours, which was not up to the standard of CJ 94-1999. Both ultraviolet rays and ozone could prolong the static duration of pure water, and the efficacy of ultraviolet rays was better than ozone. Conclusion UV light should be installed in RO purifier, the disinfected pure water by UV should be used in 16 hours after disinfection.

Objective : To investigate the injury characteristics among primary and middle school students in Panyu District, Guangzhou City, so as to provide the evidence for developing the strategies for prevention and control of injuries. Methods: The data of 6 to 18 years old primary and middle school students with initial diagnosis of injury at Panyu District Central Hospital from 2014 to 2019 were collected. The basic characteristics of injury cases, the causes, time and place of injury development were analyzed by a descriptive epidemiological method. Results: Totally 10 833 primary and middle school students with injury were reported in Panyu District from 2014 to 2019, including 7 401 boys and 3 432 girls, with a boy/girl ratio of 2.16∶1. The injury predominantly occurred in primary school students (6 903 cases, 63.72%). The causes of injury mainly included fall (4 457 cases, 41.14%), animal injury (2 593 cases, 23.94%), blunt injury (1 682 cases, 15.53%), knife/sharp instrument injury (923 cases, 8.52%) and traffic injury (731 cases, 6.75%). The place of injury development mainly included home (4 267 cases, 39.39%), school and public place (3 184 cases, 29.39%), and road/street (1 854 cases, 17.11%). The injury predominantly occurred from August to October (3 289 cases, 30.36%), and the activities at the time of injury mainly included leisure activities (3 860 cases, 35.63%), life activities (2 662 cases, 24.57%) and sports (1 929 cases, 17.81%). The characteristics of injury mainly included contusion/abrasion (4 528 cases, 41.80%), sharp instrument/bite/open injury (4 019 cases, 37.10%) and fracture (871 cases, 8.04%), and the upper limb was the main injury site (3 552 cases, 32.79%). There were 9 877 cases with mild injuries (91.18%), and 10 451 cases left hospitals after seeing a doctor (96.47%). Conclusions Fall is the main causes of injury among primary and middle school students in Panyu District, and boys and primary school students are high-risk groups for injury. Family prevention should be emphasized, and health education pertaining to injury should be intensified among students during the long holidays and leisure activities.

Objective To detect the antibiotic resistance of four kinds of gram-negative bacilli strains against seven antibiotics and to analyze the differences in antibiotic resistance between the strains isolated in intensive care unit (ICU) and common wards.Methods This study involved 3 238 gram-negative bacilli strains isolated in Beijing Tongren Hospital from January to December 2016.Of all strains, 46.6% were isolated in ICU (severe group) and 53.4% were isolated in common wards (general group).Resistance of these strains to seven kinds of antibiotics was detected and the differences between the two groups were analyzed.Results Antibiotic resistance rates of Pseudomonas aeruginosa strains to ceftriaxone, cefepime and imipenem were 41.7%, 41.2% and 39.5% in severe group and 20.9%, 21.7% and 17.1% in general group.Moreover, the differences between the two groups were all statistically significant (χ2Cefatriaxone=56.72, P<0.01;χ2Cefepime=49.12, P<0.01;χ2Imipenem=69.81, P<0.01).Antibiotic resistance rates of Klebsiella pneumoniae strains to imipenem was 17.2% in severe group and 8.8% in general group, and the difference between the two groups was statistically significant (χ2Imipenem=11.48, P<0.01).Resistance rates of Escherichia coli strains to ceftriaxone and cefepime were 72.9% and 35.8% in severe group and 44.7% and 13.3% in general group, and the differences between the two groups were statistically significant (χ2Ceftriaxone=40.13, P<0.01;χ2Cefepime=41.61, P<0.01).More than 60% of Acinetobacter baumanii strains whether they were isolated in ICU or in common wards were resistant to all the seven antibiotics, and there were no significant differences between the two groups.Conclusion Gram-negative bacilli strains isolated in ICU have higher resistance rates than those isolated in common wards and therefore antibiotics should be used differently.Regular monitoring of drug resistance should be strengthened to provide references for empirical clinical medication.

Objective: To study the immunotherapeutic effect on the esopgageal adenocarcinoma mediated by gp96-peptide complexes isolated from the same kind of tumor. Methods: gp96- peptide complexes were purified from nude mice tumors burdened by subcutaneous injection of human esophageal adenocarcinoma cell line SEG-1 . gp96-peptide complexes were carried by the dendritic cells(DC) induced from human peripheral blood mononuclear cells to prepare gp96-DC vaccine. The proliferation of lymphocytes was tested with trypan-blue stain. The quantity of interferon-?(IFN-?) released from cytotoxic T lymphocytes (CTL) was detected with ELISA method. The killing effect of CTL on target cell SEG-1 was measured with MTT. Results: We obtained 120 ?g gp96 from 55 g tumor tissue. DC, gp96, and gp96-DC all could elicit the proliferation of lymphocytes and make them becoming into CTL which released IFN-? and showed different degrees of killing effect on target cell SEG-1. gp96-DC has the strongest eliciting effect among them. At the ratio of E(effect) to T(target) as 40∶1,the killing rate was 68%.No significant difference between the effects of CTL induced by DC alone and of lymphocytes without specific antigen on SEG-1 and K562 cells. Conclusion: The gp96-peptide complexes from tumors can improve the effect of eliciting lymphocyte proliferation of DC and make the lymphocyte becoming into CTL more effectively.These CTLs show prominent killing effect on the target tumor cells.

BACKGROUND:As an important industrial solvent,benzene can cause DNA damage,chromosome aberrence,formation of DNA adducts and gene mutation. OBJECTIVE:To explore the effects of benzene on DNA and the mechanism,as well as the changes of antioxidase system it caused. DESIGN:Randomized case control study. SETTING:The Department of Clinical Laboratory of First Affiliated Hospital and Public Health College of Harbin Medical University. PARTICIPANTS:The experiment was completed in the Animal Centre in Public Health College,Harbin Medical University.Twenty-four healthy male mice of Kunming species weighed between 18 g to 22 g were chosen.The mice were provided by Experimental Animal Centre of Second Affiliated Hospital,Harbin Medical University. INTERVENTIONS:The mice were divided into control group,low dose benzene group and high dose benzene group.Inhaling benzene smoke method was used 4 hours per day to cause benzene poisoning to mice except those of the control group.The mice were executed two months later to separate marrow cells and peripheral lymphocytes and remove liver,spleen and brain to make homogenate. MAIN OUTCOME MEASURES:Single cell gel electrophoresis (SCGE) was used to assay the DNA damages of marrow cells and peripheral lymphocytes.Meanwhile,the contents of superoxide dismulase(SOD),glutathione peroxidase(GSH-Px) and malondialdehyde(MDA) in liver,spleen and brain tissues were also detected. RESULTS:The comet percentage of marrow cells and peripheral lymphocytes in two benzene poisoning groups were(83.56± 10.28),(92.54± 15.93)% ,and(41.27± 6.03)% ,(65.79± 11.62)% respectively which were much higher than those in control group[(4.13± 0.52)% ,(2.21± 0.31)% ](P< 0.01) and represented dose-response relationship.The SOD activity of liver homogenate and GSH-Px activity of high dose and low dose groups were (11 573.31± 1 938.72),(12 574.68± 1 938.72) nkat/g and (309.40± 82.85),(375.41± 55.18) nkat/g respectively which were much lower than those in control group [(16 668.67± 3 137.96),(588.62± 110.52) nkat/g] (P< 0.05).However, there was no significant difference between different dose groups. The GSH-Px activity in spleen homogenate in two experimental groups was(421.75± 124.02) and(523.10± 45.18) nkat/g respectively which was much lower than that of control group [(618.42± 57.01) nkat/g](P< 0.05) and there was significant difference between two groups (P< 0.05).In the brain homogenate of both benzene groups,the GSH-Px activity was(87.35± 19.84) and(95.02± 14.00) nkat/g respectively which was much lower than that of control group[(118.36± 7.67) nkat/g] (P< 0.05) and without difference between two groups.The MDA content in brain homogenate of high dose group was(3.99± 1.15) μ mol/mg which was much higher than that of control group [(2.58± 0.53) μ mol/g] (P< 0.05). CONCLUSION:Chronic benzene poisoning can cause DNA impairment of marrow cells and peripheral lymphocytes and reduce the activity of antioxidase.