Objective To investigate the role of cytochrome P450 2E1 (CYP2E1) in trichloroethylene (TCE)-induced skin sensitization and liver damage in guinea pigs, using diallyl sulfide (DAS), a CYP2E1 inhibitor, as an intervention. Methods Specific pathogen-free female guinea pigs were randomly divided into blank control group, solvent control group, positive control (2,4-dinitrochlorobenzene) group, TCE-exposure group, and DAS-intervention group. Skin sensitization experiments were conducted using the guinea pig TCE maximal dose-skin sensitization test. Urinary trichloroacetic acid levels were determined following TCE induction and challenge. At 48 hours after the final challenge, serum liver function markers and inflammatory cytokines levels were detected. Histopathological examination on skin and liver tissues was performed, and hepatic CYP2E1 protein expression and oxidative stress indicators were assessed. Results The sensitization rates of guinea pigs were 100.0%, 75.0%, and 33.3% in the positive control, TCE-exposure, and DAS-intervention groups, respectively, while the blank control and solvent control groups were both 0.0%. Compared with the guinea pigs in TCE-exposure group, those in the DAS-intervention group had lower urinary trichloroacetic acid levels at intradermal induction, local induction, first challenge, and 24 hours after the final challenge time point (all P<0.05). Histopathology of guinea pigs showed dermal inflammatory infiltration and basal keratinocyte necrosis in the TCE-exposure group, whereas only mild dermal inflammation was observed in the DAS-intervention group. The guinea pigs in TCE-exposure group exhibited diffuse hepatocellular necrosis, while hepatic damage in the DAS-intervention group was alleviated, characterized by only mild hepatocellular steatosis and hepatocyte swelling around the central vein. The skin sensitization rate of guinea pigs in the TCE-exposure group increased (all P<0.01), the serum alanine aminotransferase (ALT )activity, the levels of interleukin (IL)-2, IL-17, and tumor necrosis factor-α (TNF- α) increased (all P<0.05), the relative expression of CYP2E1 protein, the activity of superoxide dismutase (SOD), and the level of malondialdehyde in liver tissue increased (all P<0.05), while the activity of catalase decreased (P<0.05), compared with the blank control and solvent control groups. The serum ALT activity and the levels of IL-2, IL-17, and TNF-α of guinea pigs in DAS-intervention group reduced (all P<0.05), as well as CYP2E1 protein expression, SOD activity, and malondialdehyde level in liver tissue reduced (all P<0.05), compared with the TCE-exposure group. Conclusion TCE can induce hepatic CYP2E1 expression, thereby promoting oxidative stress and inflammatory responses, which contributes to skin sensitization and liver damage. DAS alleviates TCE-induced toxic effects on skin and liver by inhibiting CYP2E1 expression.

Objective To investigate the effects of long-term exposure to three new types of light emitting diode (LED) sources on the behavior, learning, and memory of rats. Methods A total of 160 specific pathogen-free SD rats were divided into eight groups as followed, trichromatic fluorescent lamps color temperature control group, violet-chip full-spectrum white LED group, blue-chip white LED group, and blue-chip full-spectrum white LED group based on the light sources types, with color temperature of 4 000 K and 6 500 K groups in each group using the 4×2 factorial design. There were 20 rats in each group, with half of the rats were males and half females. Rats were exposed to artificial lighting, and the illumination was set at 750 lx. The rats in each group were exposed to different lighting environments for 12 hours per day for 24 weeks. The open-field and step-down tests were conducted in rats after 24 weeks exposure, followed by sacrifice of rats and measurement of organ coefficients. Differences in body weight, organ coefficients, and neurobehavioral indexes of rats in different groups were compared. Results The spleen coefficient of female rats decreased in blue-chip white LED of 6 500 K color temperature group, and the liver coefficient of male rats decreased in the violet-chip full-spectrum white LED of 4 000 K color temperature, blue-chip full-spectrum white LED of 4 000 K color temperature, and blue-chip full-spectrum white LED of 6 500 K color temperature groups, compared with the same-sex rats in trichromatic fluorescent lamps with same-color temperature control group (all P<0.05). The result of different types of light sources compared in the open-field test showed that the index of total distance and movement speed of female rats in the blue-chip full-spectrum white LED group were lower than those in the other three groups, and the time cost to the central area was longer than that in the blue-chip white LED group and the violet-chip full-spectrum white LED group (all P<0.05). The total distance and movement speed of male rats in the blue-chip full-spectrum white LED group were longer or higher than those in the violet-chip full-spectrum white LED group (all P<0.05). Based on the comparison of color temperature, the time and total distance of male rats in 6 500 K color temperature group were lower than that in the 4 000 K color temperature group (both P<0.05). In the step-down test, both male and female rats in the blue-chip full-spectrum white LED group made more errors compared with other three groups with the same gender (all P<0.05). Conclusion Based on the experimental conditions of this study, the blue-chip full-spectrum white light LED affects behavior, learning and memory of the rats, and trichromatic fluorescent lamp has the lowest effect on neurobehavior. The color temperature also affects behavior of the rats, and high color temperature has higher risk.

The extraordinary advantages associated with mRNA vaccines, including their high efficiency, relatively low severity of side effects, and ease of manufacture, have enabled them to be a promising immunotherapy approach against various infectious diseases and cancers. Nevertheless, most mRNA delivery carriers have many disadvantages, such as high toxicity, poor biocompatibility, and low efficiency in vivo, which have hindered the widespread use of mRNA vaccines. To further characterize and solve these problems and develop a new type of safe and efficient mRNA delivery carrier, a negatively charged SA@DOTAP-mRNA nanovaccine was prepared in this study by coating DOTAP-mRNA with the natural anionic polymer sodium alginate (SA). Intriguingly, the transfection efficiency of SA@DOTAP-mRNA was significantly higher than that of DOTAP-mRNA, which was not due to the increase in cellular uptake but was associated with changes in the endocytosis pathway and the strong lysosome escape ability of SA@DOTAP-mRNA. In addition, we found that SA significantly increased the expression of LUC-mRNA in mice and achieved certain spleen targeting. Finally, we confirmed that SA@DOTAP-mRNA had a stronger antigen-presenting ability in E. G7-OVA tumor-bearing mice, dramatically inducing the proliferation of OVA-specific CLTs and ameliorating the antitumor effect. Therefore, we firmly believe that the coating strategy applied to cationic liposome/mRNA complexes is of potential research value in the field of mRNA delivery and has promising clinical application prospects.

{L-End}Objective To explore the feasibility of using positron emission tomography (PET) -computed tomography (CT) to detect brain metabolic abnormalities caused by trimethyltin chloride (TMT) poisoning. {L-End}Methods Specific pathogen free healthy SD rats were randomly divided into model group and control group with six rats in each group. Rats in the model group were intraperitoneally injected with a single dose of 10 mg/kg body mass of TMT solution, and rats in the control group were intraperitoneally injected with a single dose of an equal volume of 0.9% sodium chloride solution. Rats were anaesthetized after three days of modeling and underwent PET-CT brain scanning to detect the standardized uptake value (SUV) of ¹⁸F-2-fluro-D-deoxy-glucose (¹⁸F-FDG). After scanning, rats were sacrificed and brain tissues were collected for brain organ coefficients calculation and brain histopathological analysis. {L-End}Results The rats in the model group showed symptoms of head tremor, limb twitching, irritability and others after TMT modeling. There was no significant difference in the body mass between the two groups of rats on the third day of modeling (P>0.05). The ¹⁸F-FDG uptake in the cerebral cortex, cerebellum and brainstem of the rats in the model group was significantly weakened compared with the control group, with deceased SUV values (all P<0.05). No obvious abnormalities were found in CT images and freshly collected brain tissues of rats of the control and model groups. The brain organ coefficients of rats in the two groups showed no significant difference (P>0.05). The results of hematoxylin-eosin staining of brain tissue showed that the cerebral cortex of rats in the model group had more tiny cavities than that of the control group, and some neuronal cells and a small number of hippocampal vertebral cells were tightly and deeply stained, with the cytoplasm and nucleus poorly demarcated, and pericellular space enlarged. The results of Nissen staining showed that the arrangement of neuronal cells in the model group was slightly disordered, and the interstitial space was slightly enlarged, but no other significant abnormal changes were observed. {L-End}Conclusion PET-CT can be used in detecting the metabolic abnormalities of brain in TMT poisoning rat model, making it a sensitive detection method for TMT poisoning.

Objective To analyze result of the external quality assessment for laboratories of toxicological pathology diagnosis in organizations in China. Methods A total of 86 organizations that participated in the 2020-2021 external quality assessment in laboratory of toxicological pathology diagnosis (hereinafter referred to as "reference units") were selected as research subjects using convenient sampling method, and the assessment results were analyzed. Results The median of total score was 92, and the 0-100 percentiles were 64-100 in these 86 reference units. Among these reference units, 76 were rated as excellent, 10 as qualified, with the excellent and the qualified rate of 88.4% and 11.6%, respectively. No reference unit was rated as unqualified. The rates of excellence of the reference units in public health institutions, pharmaceutical research institutions, drug safety evaluation centers and testing companies were 95.7%, 84.2%, 85.7% and 86.7%, and the qualified rates were 4.3%, 15.8%, 14.3% and 13.3%, respectively. The distribution of excellence and qualification among the four types of reference units showed no statistical difference (P>0.05). The distribution of sample scores according to the three grades of poor, good, and excellent were 4.9%, 20.7%, and 74.5% in public health institutions, 8.6%, 23.7%, and 67.8% in pharmaceutical research institutions, 12.5%, 25.0%, and 62.5% in drug safety evaluation centers, and 5.4%, 17.5%, and 77.1% in testing companies. The proportion of excellence unit in public health institutions was higher than that in pharmaceutical research institutions (P<0.05). Conclusion The overall toxicological pathology diagnostic capabilities in China are good, and various types of reference units demonstrate comparable technical capabilities. However, there is a need for standardization of diagnostic terminology.

OBJECTIVE: To observe the sub-acute toxicity of 1-bromopropane(1-BP) oral exposure for 28 days in SD rats. METHODS: Specific pathogen free adult female SD rats were randomly assigned to the control and exposed group, 8 rats in each group. The 1-BP was suspended in corn oil and administered by gavages in a dose of 800 mg/kg body weight to rats in the exposed group, once a day, 5 days per week for 4 weeks. The rats in the control group were given equal volume of corn oil. After the last exposure, blood and urine of rats were collected for 1-BP level detection and hematological examination. Brain, heart, lung, liver, kidney and spleen of rats were collected for gross pathological examination and histopathological examination. RESULTS: The rats of exposed group showed unstable standing, weakness of hind limbs, limping and lying down from the 3 rd week of exposure. From the 1 st to 4 th week of exposure, mean body weight of rats in the exposed group were significantly lower than those of the control group(P<0.05). In the exposed group, the level of 1-BP in urine was higher than that in blood(P<0.05), and that there was positive correlation between them(Spearman correlation coefficient=0.954, P<0.01). In the control group, 1-BP was not detected. The absolute weights of brain and lung tissue in the exposure group decreased(P<0.05), meanwhile the organ coefficients of heart, liver, spleen and kidney were significantly increased compared with the control group(P<0.05). The number of red blood cells, hemoglobin concentration, hematocrit, the mean hemoglobin concentration, the total serum cholesterol and triglycerides were decreased(P<0.05). No pathological change related to 1-BP exposure was observed in the main organs of the rats in the exposed group. CONCLUSION: The sub-acute oral toxicity of 1-BP is mainly neurotoxicity and hematotoxicity. The 1-BP level in urine may reflect its exposure.

OBJECTIVE: To evaluate the diagnostic ability of toxicity pathology in patho-toxicological testing institutions in China. METHODS: The institutions participated in the 2018 Interlaboratory Comparison Activity of Toxicity Pathology Testing(hereinafter referred to as reference unit) were selected as the research subjects. The heart, spleen, skin, soft tissue, liver and mammary gland of SD rats of different groups in the 2-year carcinogenesis test were selected. The femur, knee joint and nose of Beagle dogs in the 4-week toxicity test and a total of 10 pathological tissues were selected as the comparison samples. The pathological diagnosis was carried out by the pathological diagnostic personnel of the reference unit, and the diagnostic results were reported. The expert appointed by the Toxicology and Pathology Committee of Chinese Toxicology Association compared the diagnostic results with the appointed value. RESULTS: A total of 167 pathological diagnostic personnel from 75 reference units in 24 provinces and municipalities participated in the comparison activity. The reference units were mainly distributed in East China, South China and North China, accounting for 77.3%(58/75). Totally 75 reference units fed back 750 effective diagnostic results. The qualified rates of diagnosis on heart, spleen, skin, soft tissue and breast samples were higher than 60.0%. The qualified rates of diagnosis on femur and knee joint, and nose samples were low(30.7% and 6.7%, respectively). There were 1(1.3%), 46(61.4%) and 28(37.3%) reference units rated as unqualified, qualified and excellent, respectively. CONCLUSION: Most of the testing institutions in China have a high level of patho-toxicological diagnostic ability, that can provide reliable diagnostic results for toxicology safety evaluation tests.

OBJECTIVE: To investigate the chronic toxicity and carcinogenicity of kresoxim-methyl in rats. METHODS: Specific pathogen free SD rats were randomly divided into control group and low-, medium-and high-dose groups according to the body weight of rats, 120 rats in each group with half male and half female rats. The chronic toxicity and carcinogenesis was induced in rats for 104 weeks by oral feeding. The dose of kresoxim-methyl in feed of male and female rats was 0, 75, 300 and 1 200 mg/kg. During the process of experiment, the body weight of rats was weighed. The blood biochemistry, organ coefficient and histopathology were examined at the end of the exposure, and the tumor incidence was calculated. RESULTS: There was no significant difference in mortality of the female or male rats in the four groups(P>0.05). At the 32 nd, 48 th and 56 th week after exposure, the body mass of female rats in the high dose group was lower than that in control group(P<0.05); at the 8 th, 16 th, 24 th and 32 nd week, the body mass of male rats in the high dose group was lower than that in the control group(P<0.05). The organ coefficients of heart and adrenal gland of female rats in the high dose group were higher than those in the control group and the low dose group(P<0.05). The organ coefficient of liver of male rats in the high dose group was lower than that in the control group(P<0.05). The alkaline phosphatase of male rats in the three dose groups was lower than that in the control group(P<0.05). The blood glucose of male rats in the high dose group was higher than that in the control group(P<0.05). The aspartate aminotransferase of male rats in the high dose group was lower than that in the control group(P<0.05). There was no significant difference among the three indexes in female rats(P>0.05). The tumor incidence of the control group and the low, medium and high dose groups were 68.3%, 75.0%, 75.0% and 78.8%, respectively, with no significant difference(P>0.05). The tumor incidence of the female rats was higher than that of the male rats(87.0% vs 61.5%,P<0.01).The tumor multiplicity of the above four groups were 38.3%, 35.8%, 35.0%, 39.8%, respectively, with no significant difference(P>0.05). The tumor multiplicity in female rats was higher than that in male rats(56.9% vs 17.6%,P<0.01). CONCLUSION: The no observed adverse effect level of kresoxim-methyl to female and male SD rats was 24.726 and 20.002 mg/(kg·d), respectively. No carcinogenicity of kresoxim-methyl to SD rats was observed.

OBJECTIVE: To observe the pathological changes of rat silicosis model at different time points. METHODS: The specific pathogen free SD rats were randomly divided into control group and 7, 15, 21, 30, 45, 60, 75 and 90 day model groups based on their body weight, with 5 rats in each group. Non-exposed endotracheal intubation was performed. Silicosis rat model was established by intratracheal instillation of 250 g/L silica suspension in each rat, and 0.9% sodium chloride solution was perfused into the trachea of rats in the control group. The rats in the control group were sacrificed on the 90 th day after exposure, and the model rats in the other 8 groups were sacrificed on the 7 th, 15 th, 21 st, 30 th, 45 th, 60 th, 75 th and 90 th days after the end of exposure. The gross appearance of the lung tissue of rats was observed. The rat lung tissues were stained with hematoxylin-eosin and Masson staining to observe the pathological changes, and Ashcroft score was evaluated. RESULTS: The gross observation showed that the lungs of rats in the model groups had varying degree of gray changes, hardened texture, and spots and nodules on the surface of the lobes. These changes were aggravated with the increase of time after dust exposure. The results of histopathological examination of the lungs showed that the rats developed acute alveolar inflammation, and a large number of macrophages and neutrophils were seen in the lung tissues in the 7 th and 15 th day model groups. Cellular nodules appeared in the lung tissue, and fibrosis appeared in the center of the nodule in the rats of 21 st, 30 th, and the 45 th day model groups; the silicosis nodules appeared in the lung tissues of rats in the 60 th, 75 th, and 90 th day model groups, and the small nodules gradually merged into larger ones. Simultaneously, with the increase of time after dust exposure, the lung tissue of rats gradually showed severe pulmonary fibrosis. The lung organ coefficient and Aschcroft score of rats increased with the increase of time after dust exposure(P<0.01). CONCLUSION: The rat lung changes after dust exposure. Acute alveolar inflammation occurs on the 7 th to 15 th day after dust exposure; cellular nodules develop on the 21 st to 45 th day after dust exposure; silicosis nodules develop on the 60 th to 90 th day after dust exposure. The severity of lung fibrosis after dust exposure showed a time-effect relationship in rats.

OBJECTIVE: To explore the effects of sub-acute inhalation of 1-bromopropane( 1-BP) on the ultrastructure of cerebral cortex,hippocampus,cerebellum,and brainstem in male rats. METHODS: Specific pathogen free healthy male Wistar rats were randomly divided into control group and exposure group with 6 rats in each group. The rats of exposure group received 1-BP vapor at a concentration of 5 000 mg/m3. The rats in the control group were given fresh air in a dynamic inhalation chamber system for 4 weeks(6 hours/day,5 days/week). After the end of the exposure,the cerebral cortex,hippocampus,cerebellum and brainstem of rats were collected and the ultrastructural changes were observed under transmission electron microscope( TEM). RESULTS: After 3 weeks of exposure to 1-BP,the rats in the exposure group began to have unresponsiveness and decreased muscle strength in hind limbs. The body weight of exposure group was lower than that of control group from the 1 st to the 4 th week( P < 0. 05). TEM results showed destroyed structure of the myelin sheath in the region of cerebral cortex, hippocampus, cerebellum and brainstem, and irregular nucleus, vacuolar degeneration,increased lysosome of endoplasmic reticulum,mitochondrion swelling of neuron cells,karyopyknosis of astrocytes and vacuolation in the neurite of astrocytes located in the blood brain barrier( BBB). CONCLUSION: 1-BP sub-acute inhalation exposure could damage the myelin,neuron,astrocyte and BBB in male rats. The demyelination of nerve fiber and decreased permeability of BBB was particularly noticeable.