Longitudinal study of the effects of occupational aluminium exposure on workers' cognition.

OBJECTIVE: To explore the effects of occupational aluminium(Al) exposure on workers' cognition through a longitudinal study. METHODS: The study population consisted of 276 workers in an Al factory. In 2014, we used inductively coupled plasma mass spectrometry (ICP-MS) to determine the plasma aluminium (P-Al) concentration of the workers, and a combined questionnaire to test the workers' cognitive function. Followed-up in 2016, the workers were tested again for cognitive function. Generalized linear regression was used to assess the association between P-Al concentration and cognitive scores, and multivariable logistic regression was used to assess the risk of cognitive decline caused by Al exposure. RESULTS: Generalized linear regression results showed that a non-significant association was found between the P-Al concentration and cognitive test scores (P > 0.05) in 2014. Two years later, each 10-fold increase in P-Al concentration was inversely associated with the score of Mini-Mental state examination (MMSE) (ß: -0.53, 95% CI: -0.86, -0.20) and Fuld object memory evaluation (FOME) (ß: -0.93, 95% CI: -1.62, -0.24). Each 10-fold increase in P-Al concentration was inversely associated with MMSE2016-2014 (ß: -0.38, 95% CI: -0.74, -0.01) and FOME2016-2014 (ß: -1.20, 95% CI: -1.95, -0.45). There was a statistically significant difference in the average annual rate of change of MMSE and FOME with the tertile of P-Al concentration increase (P < 0.05). The multivariable logistic regression results showed that as the P-Al concentration increased, the risk of a FOME score decline increased (Ptrend = 0.009). CONCLUSIONS: Continuous occupational Al exposure can damage workers' overall cognitive ability, especially episodic memory function.

Cross-sectional study based on occupational aluminium exposure population.

To evaluate the different characteristics of cognitive impairment caused by occupational aluminium exposure at different ages, we surveyed 1660 workers in Shanxi Aluminium Plant, China, and assessed their cognitive function and plasma aluminium concentration. In multiple linear regression, the scores of the digit-span test (DST) and digit-span backward test (DSBT) were negatively correlated with plasma aluminium concentration when concentration reached 34.52 µg/L in younger group (＜40 years), while in the middle-aged group (≥40 years) only found when concentration reached 42.25 µg/L (ß<0, P < 0.05). In logistic regression, when plasma aluminum concentration reached 42.25µg/L, odds ratios (95 % confidence interval) were 1.695 (1.062-2.705) and 3.270 (1.615-6.620) for DST, 7.644 (3.846-15.192) and 15.308 (4.180-56.059) for DSBT in middle-aged group and younger group, respectively. These results showed that aluminium exposures were associated with cognitive impairment among aluminium-exposed workers, particularly for young workers who were more susceptible.

Aluminum-induced "mixed" cell death in mice cerebral tissue and potential intervention.

The brain is one of organs vulnerable to aluminum insult. Aluminum toxicity is involved in neurobehavioral deficit, neuronal cell dysfunction, and death. The aim of this study are as follows: (1) to evaluate the repairing efficiency of Necrostatin-1 (Nec-1), a cell death inhibitor, and Z-VAD-FMK, a pan-caspase inhibitor, on Al-induced neurobehavioral deficit and neuronal cell death, in order to evidence the cell death inducing ability of aluminum, and (2) to primarily explore the possibility of treating neuronal cell loss-related disease, such as Alzheimer's disease, with Nec-1 and Z-VAD in Al-induced dementia animal model. We found Nec-1 and Z-VAD-FMK alone or in combination could reduce aluminum-induced learning and memory impairment in mice. Pathohistological results indicated that Nec-1 and Z-VAD-FMK can decrease Al-induced neuronal death cell. In addition, some cell death-associated proteins in cell death signal pathway were inhibited by Nec-1 and Z-VAD-FMK in Al-exposed mice. In conclusions, Nec-1 and Z-VAD-FMK can repair the injury of learning and memory induced by aluminum in mice. Furthermore, Nec-1 was more obvious to repair the injury of learning and memory function compared with Z-VAD-FMK. Nec-1 and Z-VAD-FMK can repair the Al-induced morphological injury of cell and reduce the amounts of dead cell, and repairing effects were more significant at higher doses. The effect of Nec-1 was stronger than Z-VAD-FMK, though their mechanism was different. The combination of them had the strongest effect. Our study evidenced Al-induced neuronal necroptosis and apoptosis existing in animal model and suggested potential therapeutic effects of Nec-1 and Z-VAD-FMK on neuronal cell death in neurodegenerative diseases.

Effects of exposure to aluminum on long-term potentiation and AMPA receptor subunits in rats in vivo.

OBJECTIVE: To explore the effects of exposure to aluminum (Al) on long-term potentiation (LTP) and AMPA receptor subunits in rats in vivo. METHODS: Different dosages of aluminum-maltolate complex [Al(mal)3] were given to rats via acute intracerebroventricular (i.c.v.) injection and subchronic intraperitoneal (i.p.) injection. Following Al exposure, the hippocampal LTP were recorded by field potentiation technique in vivo and the expression of AMPAR subunit proteins (GluR1 and GluR2) in both total and membrane-enriched extracts from the CA1 area of rat hippocampus were detected by Western blot assay. RESULTS: Acute Al treatment produced dose-dependent suppression of LTP in the rat hippocampus and dose-dependent decreases of GluR1 and GluR2 in membrane extracts; however, no similar changes were found in the total cell extracts, which suggests decreased trafficking of AMPA receptor subunits from intracellular pools to synaptic sites in the hippocampus. The dose-dependent suppressive effects on LTP and the expression of AMPA receptor subunits both in the membrane and in total extracts were found after subchronic Al treatment, indicating a decrease in AMPA receptor subunit trafficking from intracellular pools to synaptic sites and an additional reduction in the expression of the subunits. CONCLUSION: Al(mal)3 obviously and dose-dependently suppressed LTP in the rat hippocampal CA1 region in vivo, and this suppression may be related to both trafficking and decreases in the expression of AMPA receptor subunit proteins. However, the mechanisms underlying these observations need further investigation.

[Effects of maternal exposure to nano-alumina during pregnancy on neurodevelopment in offspring mice].

OBJECTIVE: To observe the effects of maternal exposure to nano-alumina during pregnancy on the neurodevelopment in offspring mice. METHODS: Female ICR mice began to be exposed to nano-alumina 10 d before mating, and the nano-alumina exposure lasted till offspring mice were born. All the female mice were randomly divided into 5 groups: solvent control group (saline), nano-carbon group (11.76 mg/ml), micro-alumina group (50 mg/ml), 50 nm alumina group (50 mg/ml), and 13 nm alumina group (50 mg/ml). All the mice were treated by nasal drip (10 µl/time) 3 times daily till offspring mice were born. Physiological indices, reflex and sensory function test, endurance test, Morris water maze test, positioning and navigation test, and open field test were used to evaluate the neurodevelopment of newborn mice. RESULTS: On day 28, the body weight of 13 nm alumina group (16.73±4.04 g) was significantly lower than that of solvent control group (20.45±2.50 g) (P<0.01); the 13 nm alumina group had significantly delayed time to ear opening compared with the solvent control group (4.91±0.78 d vs 4.45±0.50 d, P<0.01); compared with the solvent control group, the nano-carbon group, micro-alumina group, 50 nm alumina group, and 13 nm alumina group had significantly delayed time to eruption of teeth (10.05±0.23 d vs 10.32±0.48 d, 10.75±0.45 d, 10.32±0.47 d, and 10.79±0.49 d, P<0.05 or P<0.01). On days 4 and 7 after birth, compared with the solvent control group, other groups had significantly decreased proportions of mice which passed the cliff avoidance test (P < 0.05 or P < 0.01). On days 12 and 14 after birth, compared with the solvent control group, the nano-carbon group, 50 nm alumina group, and 13 nm alumina group had significantly reduced pre-suspension time in the endurance test (P < 0.05 or P < 0.01). The Morris water maze and positioning and navigation tests showed that the 13 nm alumina group had a significantly increased 5 d incubation period compared with the solvent control group (P < 0.05); compared with the solvent control group, other groups had significantly reduced numbers of platform crossings (P < 0.05 or P < 0.01). The open field test showed that the nano-carbon group and 13 nm alumina group had reduced numbers of rearings compared with the solvent control group (P < 0.05); compared with the solvent control group, other groups had significantly reduced numbers of modifications (P < 0.01). CONCLUSION: Maternal exposure to nano-alumina (13 nm) during pregnancy has inhibitory effects on the physical development and early behavioral development in newborn mice and can also inhibit the learning and memory abilities and adaptability to new environment in offspring mice. The neurodevelopmental toxicity of nano-alumina to newborn mice increases as the particle sizes of nano-alumina decrease, which has been demonstrated by the endurance test and number of rearings.

[A method for simultaneous assay of propulsion and absorption in small intestine].

OBJECTIVE: To develop a method for simultaneous assay of propulsion and absorption in small intestine. METHODS: The mice were administrated through gastric tube with mixed reagents containing 0.12% phenol red, D-xylose (1.25%, 2.5% and 5%) and 15% gelatin. The influence of phenol red on D-xylose absorption and the influence of D-xylose on small intestine propulsion rate were investigated by measuring serum concentration of D-xylose with phloroglucinol method. RESULTS: At 10 min, no significant difference was found between 5% D-xylose mixed reagent group and 5% D-xylose control. At 15 min, small intestine propulsion rate in 5% D-xylose mixed reagent group, but not in 2.5% and 1.25% D-xylose mixed reagent groups, was significantly higher than in phenol red control (P<0.05). CONCLUSION: Gastric administration of mixed reagent containing 0.12% phenol red, 5% D-xylose and 15% gelatin can simultaneously assay propulsion and absorption of small intestine in mice.

[Changes of brain oxidative stress induced by nano-alumina in ICR mice].

OBJECTIVE: To investigate the brain oxidative stress injury induced by nano-alumina particles in ICR mice. METHODS: Sixty male ICR mice were randomly divided into 6 groups: control group, solvent control group, 100 mg/kg micro-alumina particles group, 3 groups exposed to nano-alumina particles at the doses of 50, 100 and 200 mg/kg. The mice were exposed by nasal drip for 30 days. Then levels of malondialdehyde (MDA), glutathione (GSH), superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-PX) in brain tissues of mice were detected. RESULTS: There was no difference of SOD activity in mouse brain between control group [(17.32 +/- 6.23)U/gHb] and 50 mg/kg nano-alumina particles group [(17.89 +/- 1.82) U/gHb]. The SOD activity [(4.93 +/- 2.30)U/gHb] in 200 mg/kg nano-alumina particles group was significantly lower than that in control group (P < 0.05). The MDA levels in 3 nano-alumina particles groups were (0.76 +/- 0.13), (1.00 +/- 0.30) and (1.16 +/- 0.39)nmol/ml, respectively, which were significantly higher than that [( 0.24 +/- 0.09)nmol/ml] in control group (P < 0.05). The GSH levels in 3 nano-alumina particles groups were (0.72 +/- 0.08), (0.55 +/- 0.19) and (0.61 +/- 0.20)mg/gpro, respectively, which were significantly lower than that [(1.55 +/- 0.34)mg/gpro]] in control group (P < 0.05). The CAT activity in 50 and 100 mg/kg nano-alumina particles groups were (10.40 +/- 3.84) and (10.40 +/- 2.00)U/mgpro, respectively, which were significantly higher than that [(5.79 +/- 0.96) U/mgpro] in control group (P < 0.05). The CAT activity [(3.25 +/- 1.04)U/mgpro] in 200 mg/kg nano-alumina particles group was significantly lower than that in control group (P < 0.05 ). CONCLUSION: Nano-alumina particles can induce the oxidative stress damage in brain tissues of mice.

[The effects of caspase-3 siRNA on the neurobehavior of mice exposed to aluminum].

OBJECTIVE: To investigate the effects of caspase-3 siRNA on the neurobehavior of mice exposed to aluminum. METHODS: Male KunMing mice (3 months old) were randomly divided into 4 groups by weight:blank control group (4 microl normal saline), Al group (4 microl 0.5% AlCl3), Al plus empty vector group(3 microl 0.5% AlCl3 plus control siRNA expression vector)and Al plus RNAi group (3 microl 0.5% AlCl3 plus targeted siRNA expression vector). All groups were treated by lateral cerebral ventricle micro-injection for 5 days. The neurobehavior was tested by the Morris water maze test, Open-field and Step-down tests for all treated mice. Pathological changes in hippocampus was observed by electron microscopy, the caspase-3 gene expression levels were detected using RT-PCR. RESULTS: The results of Step-down test indicated that as compared with control group, the latent time [LT, (44.67 +/- 10.60) s] in A1 group decreased significantly, the error number (3.63 +/- 0.52) in Al group increased significantly and the LT [(68.00 +/- 14.70) s] in Al plus empty vector group decreased significantly (P<0.05). the LT [(239.50 +/- 19.36) s] in Al plus RNAi group increased significantly and the error number in Al plus RNAi group decreased significantly, as compared with Al group (P<0.05). The results of Morris water maze test showed that as compared with control group, the LT in Al group increased significantly, and residence time in the former platform quadrant decreased significantly and the LT in Al plus empty vector group increased significantly (P<0.05). The LT in Al plus RNAi group was significantly longer than that in Al group (P<0.05). The results of open-field test demonstrated that as compared with control group, the time in the central grid in Al group and Al plus empty vector group increased significantly, the rearing number and the modification number in Al group and Al plus empty vector group decreased significantly (P< 0.05). As compared with Al group, the time in the central grid in Al plus RNAi group decreased, the inter-cell number, the rearing number and the modification number increased significantly (P<0.05). The results of electron microscopic examination exhibited that a slight change of hippocampal cells appeared in control group, the obvious pathological changes of hippocampal cells appeared in Al group and Al plus empty vector group, but the pathological changes of hippocampal cells in Al plus RNAi group significantly reduced as compared with Al group. The results of thionin staining indicated that the layers of neural cells of hippocampal CA3 were more clear and there was not obvious denatured injury of neural cells of hippocampal CA3 in control group. The number and Nissl body color of neural cells of hippocampal CA3 in Al group and Al plus empty vector group decreased significantly. After RNA interference, the number and Nissl body color of neural cells of hippocampal CA3 increased obviously. The expression levels of caspase-3 gene in Al group and Al plus empty vector group were 2.24 +/- 0.57 and 2.28 +/- 0.33, respectively, which were significantly higher than that (1.00 +/- 0.00) in control group (P<0.05). The expression level of caspase-3 gene in Al plus RNAi group was 0.44 +/- 0.08, which was significantly lower than those in Al group and control group (P<0.05). CONCLUSION: Aluminum can decrease the learning and memorizing ability, and inhibited the activity or exploration function of mice. It is suggested that Caspase-3 siRNA may reduce the neurotoxicity induced by aluminum to a certain extent.

Development and evaluation of real-time PCR assay for the detection of Babesia orientalis in water buffalo (Bubalus bubalis, Linnaeus, 1758).

Babesia orientalis is the causative agent of babesiosis in water buffalo (Bubalus babalis, Linnaeus, 1758). In this study, a TaqMan real-time PCR assay was developed for quantitative detection of B. orientalis in water buffalo. Hybridization probe and oligonucleotide primers were designed based on the v4 region of 18S rRNA gene. Detection limit was determined at 2 parasites. Blood samples were collected from experimentally infected water buffalo, as well as from 180 field samples, which were collected from 4 different geographical locations to the north and south of the Yangtse River. The parasite was detected by real-time PCR on day 2 until day 39 post-infection, while reverse line blot (RLB) was on day 6 until day 36 in experimentally infected water buffalo. For the results of 180 field samples, statistical analysis showed no significant difference in relative effectiveness of real-time PCR and RLB. The analysis also indicated that there was no difference in the prevalence of B. orientalis between the regions of south and north of the Yangtse River by both the real-time PCR assay and RLB detection. These results indicated that the parasite infection has spread to the north of the Yangtse River.

[Cell toxicity assessment methodologies applied in the study of the toxicity of nano-alumina to nerve cells].

OBJECTIVE: To observe the effect of nano-alumina on nerve cell viability through different detection kits of cell viability, using micro-alumina and nano-carbon as controls. METHODS: Primary culturing nerve cells of mouse in vitro, which were exposed to 7 doses of 0 µmol/L, 62.5 µmol/L, 125.0 µmol/L, 250.0 µmol/L, 500.0 µmol/L, 1.0 mmol/L, 2.0 mmol/L concentrations of nano-alumina (nano-Al), micro alumina (micro-Al) and nano-carbon (nano-C), detecting cell viability (A(570) values) with CCK-8, MTT and LDH methods. RESULTS: (1) The results of CCK-8 kit showed that, in doses of 250.0 µmol/L - 2.0 mmol/L, the cell viability values of nano-alumina (the values of A(570) were 0.878 ± 0.009, 0.823 ± 0.016, 0.647 ± 0.008, 0.594 ± 0.013, respectively) were significantly lower than that of micro-Al (the values of A(570) were 0.960 ± 0.008, 0.951 ± 0.036, 0.833 ± 0.008, 0.708 ± 0.012, respectively) and nano-C (the values of A(570) were 0.977 ± 0.003, 0.973 ± 0.002, 0.924 ± 0.006, 0.891 ± 0.023, respectively). While, comparing nano-Al with the same dose of micro-Al, there was significant difference (the t values were -0.082, -0.128, -0.186, -0.114, respectively, P < 0.01), and so as to the comparison of nano-Al with the same dose of nano-C (the t values were -0.099, -0.150, -0.277, -0.297, respectively, P < 0.01). (2) MTT results showed that in the doses of 500.0 µmol/L and 1.0 mmol/L, the cell viability of nano-Al (the values of A(570) were 0.648 ± 0.095 and 0.575 ± 0.061) were lower than that of micro-Al (the values of A(570) were 0.830 ± 0.044 and 0.816 ± 0.014) and nano-C (the values of A(570) were 0.889 ± 0.009 and 0.765 ± 0.049), and the differences were significant (nano-Al compared with the same dose of micro-Al, the t values were -0.183 and -0.242, P < 0.01; nano-Al compared with the same dose of nano-C, the t values were -0.241 and -0.190, P < 0.01). (3) LDH results showed that in the dose from 125.0 µmol/L to 2.0 mmol/L, the LDH release of nano-Al group (the values of A(570) were 1.862 ± 0.102, 1.905 ± 0.066, 1.930 ± 0.037, 1.946 ± 0.033, 1.967 ± 0.068, respectively) were higher than that of nano-C (the values of A(570) were 1.484 ± 0.110, 1.559 ± 0.039, 1.663 ± 0.014, 1.732 ± 0.076, 1.765 ± 0.073, respectively), and the differences were significant (the t values were -0.377, 0.346, 0.266, 0.213, 0.202, respectively, P < 0.01). In the dose from 125.0 µmol/L to 1.0 mmol/L, the LDH release of nano-Al group were higher than that of micro-Al (the values of A(570) were 1.578 ± 0.011, 1.639 ± 0.025, 1.727 ± 0.024, 1.808 ± 0.020, respectively), and the differences were significant (the t values were 0.284, 0.266, 0.202, 0.172, respectively, P < 0.01). CONCLUSION: The toxicity of nano-Al is greater than nano-C and micro-Al on the viability of nerve cells; LDH is more suitable for detecting changes of cell viability after the effect of nano-materials than CCK-8 and MTT.

[Effect of necrostatin-1 on apoptosis induced by aluminum and its mechanism].

OBJECTIVE: To study the effect of necrostatin (Nec-1) on apoptosis induced by aluminum (Al), and approach the mechanism. METHODS: Neural cell death model was made by 4 mmol/L Al treated neuroblastoma cells (SH-SY5Y). Cell viabilities were detected at different concentrations of Al and/or Nec-1. Hoechst 33342/PI double staining was used to observe apoptosis and (or) necrosis that were quantified by flow cytometry using Annexin V/PI double staining. Apoptotic pathway was tested by activities of Caspase-3, Caspase-8 and Caspase-9. In addition, the expression of NF-kappa B and Cyt-c was measured by immunocytochemistry. RESULTS: Cell viabilities were significantly decreased with the increasing concentrations of Al (P < 0.05), which could be significantly upregulated by 60 micromol/L Nec-1 (P < 0.05) and were correlated with the concentrations of Nec-1 (P < 0.05, P < 0.01). Apoptosis and necrosis were observed under fluorescent microscope and quantified by flow cytometry, which suggested an increasing trend of apoptotic and necrotic rates (P < 0.05, P < 0.01). Whereas, Nec-1 could not only decrease the necrotic rate but also apoptotic rate as well (P < 0.05, P < 0.01). Data of Nec-1 on caspases activities showed that Nec-1 could not affect Caspase-9 activity (P > 0.05) and Cty-c protein expression as well (P > 0.05). However, Nec-1 could reduce Caspase-8 activity significantly (P < 0.05, P < 0.01) and increase NF-kappa B protein expression (P < 0.05, P < 0.01) and finally decrease Caspase-3 activity (P < 0.05). CONCLUSION: Nec-1 could reduce cell apoptosis induced by Al, through Caspase-8 pathway, and up-regulate the expression of NF-kappa B protein.

[Changes of mitochondria membrane potential and cytoplasmic cytochrome C in neuron apoptosis induced by benzo(a)pyrene].

OBJECTIVE: To investigate the changes of mitochondria membrane potential and cytoplasma cytochrome C as the mechanism of neuron apoptosis induced by B(a)P. METHODS: Primary neurons were dissociated from cerebral cortex of 1 - 3 days old SD rats and cultured with DMEM incubator at 37 degrees C. After 5 days' cultivation, the neurons were added S9 and B(a)P, and the concentrations of treated B(a)P were 0, 10, 20 and 40 micromol/L respectively. After administering of B(a)P, the neurons were cultivated for 40 hours. Apoptosis rate was measured by flow cytometry using Annexin V-FITC and propidium iodide (PI) staining, and the changes in mitochondrial potential (DeltaPsim) were tested with Rhodamine fluorescence (R2123) technique. Preparation of cytosolic extracts by centrifugation. Western blotting analysis was used to evaluate the level of cytochrome C of cytoplasm. RESULTS: The apoptotic rate of neuron increased in both the middle dose group and the high dose group compared with controls, and had a dose-response tendency with the concentration of B(a)P. Moreover mitochondrial potential decreased in a dose dependent manner. There was a negative correlation between DeltaPsim and the apoptotic rate of neurons (r = -0.763, P < 0.05); Western blotting analysis showed cytoplasmic cytochrome C level increased significantly, which was positively related with neuron apoptosis (r = 0.831, P < 0.01). CONCLUSION: Loss of mitochondria membrane potential and increase of cytoplasma cytochrome C may be the main cause of neuron apoptosis induced by B(a)P.

Small hairpin RNA interference of the Nogo receptor inhibits oxygen-glucose deprivation-induced damage in rat hippocampal slice cultures.

In adult mammals, CNS damage does not repair well spontaneously. The Nogo receptor (NgR) signaling pathway prevents axonal regrowth and promotes neuronal apoptosis. This pathway, and pathways like it, may be part of the reason why nerves do not regrow. A number of preclinical experiments inhibiting portions of the NgR pathway have yielded limited induction of nerve repair. Here, we developed a small hairpin RNA (shRNA) to knock down NgR expression. With the use of rat hippocampal slices in tissue culture, we induced neuronal damage similar to that of ischemia-reperfusion injury by exposing the cultured tissues to oxygen-glucose deprivation. We then assayed the effect of NgR knockdown in this model system. Adenovirally delivered NgR shRNA decreased NgR mRNA and protein expression. Thirty minutes of oxygen-glucose deprivation resulted in widespread tissue damage, including apoptosis and loss of neurite extension, 72 h after termination of oxygen-glucose deprivation. The NgR shRNA knockdown reduced, but did not eliminate, the effects of oxygen-glucose deprivation. Thus, NgR shRNA shows promise as a potential tool for the treatment of nerve damage.

[Role of necroptosis in aluminum induced SH-SY5Y cell death].

OBJECTIVE: To study whether necroptosis exists or not in neural cell death induced by aluminum. METHODS: SH-SY5Y cells were treated with 4 mmol/L AlCl(3) x 6H(2)O The cell viability was determined with CCK-8 kit after treated with Nec-1 at different dosages (0, 30, 60, 90 micromol/L). Mitochondria membrane potential (MMP), content of reactive oxygen species (ROS), and apoptotic rate/necrotic rates were measured with cytometry. RESULTS: Nec-1 ameliorated the necrotic-like cell morphology, the cell viability were 0.28 +/- 0.05, 0.58 +/- 0.03, 0.68 +/- 0.04, and 1.03 +/- 0.17, there were significant differences between the Nec-1 treated groups and that of controls (t values were 3.25, 3.36, 4.56; P < 0.05). After Nec-1 treatment, the necrotic rates were 16.46% +/- 0.54%, 10.40% +/- 0.64%, 5.43% +/- 0.68%, and 6.28% +/- 0.35%, there were significant differences between the Nec-1 treated cells and that of controls (t values were 3.62, 7.32, 6.96; P < 0.05); while the apoptotic rates were 8.68 +/- 0.36, 7.66 +/- 0.53, 5.68 +/- 0.41, and 4.13 +/- 0.41, there was no significant difference among the groups (F = 6.33, P = 0.11). Cytometry had shown the increased cell MMPs after Nec-1 treatment, which were 67.54 +/- 6.36, 49.42 +/- 5.96, 84.79 +/- 6.86, and 95.51 +/- 7.01, there were significant differences as comparing MMPs of the middle and high dosage of Nec-1 treated cells with those of controls (t values were 3.21, 4.01; P < 0.05); while ROS contents in the Nec-1 treated SH-SY5Y cells were 54.07 +/- 3.32, 52.79 +/- 2.36, 54.68 +/- 1.91, and 59.23 +/- 2.96, there was no significant difference among the groups (F = 5.26, P = 0.19). CONCLUSION: Nec-1, as a specific inhibitor of necroptosis, might effectively block the cell death pathway induced by aluminum, it indicates that necroptosis should be one of the major causes of the SH-SY5Y cell toxicity induced by aluminum, and necroptosis also plays an important role in aluminum induced SH-SY5Y cell death.

[Lipid peroxidation injury and endoplasmic reticulum stress in Al-induced apoptosis].

OBJECTIVE: To study the role of lipid peroxidation injury and endoplasmic reticulum stress in Al-induced apoptosis. METHODS: Neurons from 0-3 day rats were cultured and treated with different concentrations of AlCl3.6H2O. Morphologic changes of neurons and endoplasmic reticulum were observed under fluorescent and transmission electron microscope; activities of superoxide dismutase (SOD), malondialdehyde (MDA) and ATP enzymes were detected. RESULTS: Typical morphologic changes in neurons apoptosis and endoplasmic reticulum were found under fluorescent and transmission electron microscope; SOD enzyme viability and ATP enzyme viability were significantly increased in the low-dosage group, but reduced in mid and high-dosage group (P < 0.01), whereas MDA levels decreased in the low-dosage group, but increased in mid and high-dosage group (P < 0.01). CONCLUSION: Aluminum may induce neurons apoptosis, and lipid peroxidation injury in endoplasmic reticulum plays an important role in the apoptosis progression.

Effects of benzo[a]pyrene on autonomic nervous system of coke oven workers.

Objectives are to investigate the effects of benzo[a]pyrene (B[a]P) on the autonomic nervous system of coke oven workers. One hundred eighty-four coke oven workers were divided into 3 groups according to their working sites (coke oven bottom group, coke oven side group and coke oven top group), and 93 referents were recruited. B[a]P monitored by air sampling pumps as well as urinary 1-hydroxypyrene (1-OH-Py) was determined by high performance liquid chromatograph with a fluorescence detector (HPLC-FD). The autonomic nervous system (ANS) function was determined by 4 tests: Valsalva Manoeuvre heart rate variation (HR-V), variation of heart rate when breathing deeply (HR-DB), variation of heart rate when instantly standing up (HR-IS, including RR30:15 and RRmax:min) and variation of blood pressure when instantly standing up (BP-IS). The B[a]P mean concentrations in coke oven bottom, coke oven side and coke oven top were 19, 185 and 1,623 ng/m(3), respectively. The levels of urinary 1-OH-Py were markedly higher in the 3 exposed groups than that in the referent group (p<0.01). No significant difference was found in each group between smokers and non-smokers (p>0.05). Compared with referents, HR-V decreased significantly in coke oven workers (p<0.01), representing modulation of parasympathetic nervous function. However, no statistical differences were found in HR-DB, RR30:15, RRmax:min and BP-IS between the exposed groups and the control group (p>0.05). HR-V decreased with the increment of 1-OH-Py (p<0.05), and results of multiple linear stepwise regression demonstrated that external exposure level and duration of education entered the HR-V model; age was a significant factor of HR-DB and RRmax:min, but no variable was involved in RR30:15 and BP-IS regression. Benzo[a]pyrene affects the autonomic nervous function of coke oven workers mainly by down-regulating the parasympathetic nervous function.

[Selection of bak siRNA sequences and its influence on Al-induced apoptosis of SH-SY5Y cell line].

OBJECTIVE: To find the optimal design of small interfering RNA compounds, transfection concentration and transfection time to reduce the Al-induced apoptosis in SH-SY5Y cells. METHODS: Three siRNA sequences on bak gene were designed and transfected into SH-SY5Y cells, which were treated at various concentrations of aluminum. Cell viability was detected by CCK-8 kit on different siRNA sequences, various transfection concentrations, and diverse transfection courses. Transfection efficiency was determined by fluorescent staining of CY3, and interference efficiency was measured by QRT-PCR. Besides, immunohistochemical staining was used to express Bak protein content. Finally, apoptotic rate and necrotic rate in Al treated SH-SY5Y cells transfecting by the selected bak siRNA 1 were detected. RESULTS: Based on the viability of siRNA sequences, siRNA 1 was selected as the optimal siRNA sequences. The optimal transfection concentration was 10 nmol/L, and the optimal time course was 24 h after transfection. The transfection efficiency was above 90% and the interference efficiency with bak gene was 57.76%. Furthermore, there was significant transfection effect on Bak protein. The apoptotic rate in Al treated SH-SY5Y cells were significantly decreased by bak siRNA 1 transfection. CONCLUSION: Apoptosis is one of the major cell death pathways in SH-SY5Y cells induced by aluminum. When chemically synthesized siRNA is inducted to neural cells, it can significantly reduce bak gene level, decrease Bak protein expression and apoptotic rate, which may serve as the basis for preventing neural cells apoptosis and inhibiting the development of neurodegenerative diseases.

[Role of Bcl-2 and Bax protein contents and their gene expression in Al-induced neurons apoptosis].

OBJECTIVE: To study the role of Bcl-2 and Bax protein contents and their gene expression in Al-induced neurons apoptosis. METHODS: Neurons from 0 - 3 day rats were cultured and treated with different concentrations of AlCl(3 x 6) H2O. The cell apoptosis was observed by the TUNEL method and under the scan electron microscope. Bcl-2 and Bax protein contents were detected by the immunochemistry method while their gene expressions were measured by the RT-PCR method. RESULTS: (1) DNA fractions in the TUNEL method increased with the rising aluminum concentration. Blebbings and apoptosis bodies on the surface of the neurons were clearly observed under the scan electron microscope. (2) Bcl-2 protein contents and their gene expression decreased with the rising aluminum concentration (P < 0.01, r = -0.695; P < 0.05, r = -0.647), while Bax increased at the same time (P < 0.01, r = 0.676; P < 0.01, r = 0.794), the value of Bcl-2/Bax was related with the aluminum concentration (P < 0.01, r = -0.655; P < 0.01, r = -0.777). CONCLUSION: The aluminum may induce neurons apoptosis. Bcl-2 and Bax protein contents and their gene expression may play an important role in Al-induced apoptosis.

[Effect of 1, 2-dichloroethane on blood brain barrier].

OBJECTIVE: To investigate the effect of 1, 2-dichloroethane (1, 2-DCE) on blood brain barrier. METHODS: Acute toxic encephalopathy model was copied with the consecutive static inhalation of 1, 2-DCE. The water content of brain tissue was measured, and the blood brain barrier permeability was detected with lanthanum nitrate. The brain microvascular endothelial cells and neuroglial cells were cultured in vitro, which were administrated with 1, 2-DCE. The cell morphologic structures were observed under light microscope and electron microscope. RESULTS: (1) The extracellular edema was most found in the cerebral tissue and the leakage of lanthanum particles through the barrier were found with the lanthanum tracking method. (2) The water content in cerebral cortex in the moderate and high dose groups was significantly higher than that in the control group and became severer with the increases of the intoxicated time. The water content in cerebral medulla was significantly increased only at 6 hours after the intoxication. (3) The normal morphological structure of brain microvascular endothelial cells and neuroglial cells could be injured by 1, 2-DCE, and the injury to neuroglial cells caused by 1, 2-DCE occurred earlier and severer than that to brain microvascular endothelial cells. CONCLUSION: 1, 2-DCE can damage blood brain barrier and induce cerebral edema.

[Effect of aluminum on neuronal mitochondria of rats].

OBJECTIVE: To observe and explore the effect of aluminum on mitochondria in nerve cells of rats. METHODS: Nerve cells of new born rats (1-3 days) were cultured. Ultrastructure of mitochondria, cell death rate (CDR), reactive oxygen species (ROS), mitochondrial membrane potential (MMP) and MTF were performed to investigate the alteration of mitochondrial structure and functions in cultured nerve cells. RESULTS: Aluminum can impair the ultrastructure of cultured nerve cells of rats. Increased CDR, enhanced ROS, decreased MMP, and decreased activity of enzyme in mitochondria were investigated in the group of Al3+ 100 micromol/L and Al3+ 500 micromol/L. CONCLUSION: The present study shows that the alteration of mitochondrial structure and functions have played important roles in neurotoxic mechanism induced by aluminum.