Jianjun Deng

Oxidative stress and cell cycle arrest induced by short-term exposure to dustfall PM 2.5 in A549 cells

It was reported that in vitro short-term exposure to PM2.5 caused different lung diseases through inflammatory response, immune toxicity, oxidative stress, and genetic mutations. However, the complex molecular biological mechanism for its toxicity had not been fully elucidated. Therefore, the present study investigated the cytotoxicity, oxidative damage, mitochondria damage, apoptosis, and cell cycle arrest of NX and QH PM2.5 in A549 cells. Further, cell cycle arrest-related gene levels in PM2.5-induced A549 cells were also detected. Our results suggested that PM2.5 reduced the cell viability in A549 cells. Simultaneously, excessive ROS decreased MMP levels and damaged mitochondrial membrane integrity and induced mitochondrial oxidative damage through the oxygen-dependent killer route, resulting in mitochondrial damage and cell apoptosis. Besides, the results also showed that PM2.5 induced A549 cell cycle alteration in G2/M phase after co-culture for 24xa0h. G2/M phase arrest was induced by upregulation of p53 and p21 and downregulation of CDK1 mRNA expression. In addition, lncRNA Sox2ot might play an important role as the specific oncogenes and it participated in G2/M phase arrest by regulating the expression of EZH2.

Chrysotile and rock wool fibers induce chromosome aberrations and DNA damage in V79 lung fibroblast cells

According to global estimates, at least 107,000 people die each year from asbestos-related lung cancer, mesothelioma, and asbestosis resulting from occupational exposure. Chrysotile accounts for approximately 90% of asbestos used worldwide. Artificial substitutes can also be cytotoxic to the same degree as chrysotile. But only a few researchers focused on their genetic effects and mutagenicity information which is useful in evaluating the carcinogenicity of chemicals. In this study, chrysotile from Mangnai, Qinghai, China, and an artificial substitute, rock wool fiber were prepared as suspensions and were tested at concentrations of 50, 100, and 200xa0μg/ml in V79 lung fibroblasts. Chromosome aberrations were detected by micronucleus assay after exposure for 24xa0h, and DNA damage were estimated by single cell gel electrophoresis after exposure for 12, 24, or 48xa0h. According to the results, chrysotile and rock wool fibers caused micronuclei to form in a dose-dependent manner in V79 cells; olive tail moment values increased in a dose- and time-dependent manner. When V79 cells were exposed to a concentration of 200xa0μg/ml, the degree of DNA damage induced by chrysotile fibers was greater than rock wool fibers. Our study suggests that both chrysotile and rock wool fibers could induce chromosome aberrations and DNA damage. These materials are worthy of further study.

Interface effect of natural precipitated dust on the normal flora of Escherichia coli and Staphylococcus epidermidis

This study aimed to evaluate the interface effect between five types of natural precipitated dust and two normal floras. Five kinds of natural dust (FC-1#, FC-2#, FC-15#, FC-18#, and FC-21#) were collected, and particle size and chemical components were detected by laser particle size analyzer and X-ray fluorescence (XRF). The elements, bacterial count, glucose (GLU) consumption, pH, and three biochemical indicators were measured after being co-cultured with Escherichia coli and Staphylococcus epidermidis in vitro. In addition, the changes of bacterial morphology were observed by scanning electron microscopy (SEM). Results showed that most particles contained a high level of SiO2, which diameter ranged from 0.3 to 1.0xa0μm. The concentration of Ca showed s significant increase upon interaction with E. coli and S. epidermidis in all dusts (pxa0<xa00.01). Moreover, FC-1# and FC-21# induced obvious growth in bacterial count, glucose consumption, and pH after they reacted with two normal floras (pxa0<xa00.05). Besides, the results also showed an apparent increase in the concentration of pyruvate, β-galactosidase, and alkaline phosphatase (AKP) after being co-cultured with E. coli and S. epidermidis, in which FC-1# is enhanced in the most obvious. The E. coli interacted with dust made more indentations in surface, and the configuration became thin and long. Some broken bacteria were present, and bacterial wreckage was visible. Plenty of S. epidermidis interacted with dust gathered in the indentations of dust, particularly in pleated surfaces. Further, these findings demonstrated that the alkaline dust with higher Ca content stimulated the growth of bacteria, and irregularly shaped or thin dust would be easier to combine with bacteria and conduct interface effect.

The interface interaction behavior between E. coli and two kinds of fibrous minerals

In the present, studies of interaction between human normal flora and fibrous mineral are still lacking. Batch experiments were performed to deal with the interaction of Escherichia coli and two fibrous minerals (brucite and palygorskite), and the interface and liquid phase characteristics in the short-term interaction processes were discussed. The bacterial concentrations, the remnant glucose (GLU), pyruvic acid, and the activity of β-galactosidase and six elements were measured, and the results show that the promoting effect of brucite on the growth of E. coli was more significant than that of palygorskite. FTIR and XRD analysis results also confirmed E. coli has obviously dissolved on brucite and damage effect on palygorskite silicon structure. SEM results show that the interfacial contact degree between E. coli cells and brucite fibers was higher than that of palygorskite. These may be due to the zeta potential difference between E. coli and palygorskite was 14.57–22.37xa0mV, while it of brucite was 44.04–64.24xa0mV. The elements dissolving of two fibrous minerals not only increased regularly to liquid EC but also had a good buffer effect to the decrease of liquid pH. Studies of short-term interaction between E. coli and brucite and palygorskite can help to understand the effect of fibrous minerals on microeubiosis of human normal flora and the contribution of microbial behaviors on the fibrous minerals weathering in the natural environment.

Lung injury and expression of p53 and p16 in Wistar rats induced by respirable chrysotile fiber dust from four primary areas of China

Chrysotile products were widely used in daily life, and a large amount of respirable dust was produced in the process of production and application. At present, there was seldom research on the safety of chrysotile fiber dust, and whether its long-term inhalation can lead to lung cancer was unknown. In order to determine whether respirable chrysotile fiber dust of China caused lung cancer, four major chrysotile-producing mine areas in China were selected for this study. Chrysotile fibers were prepared into respirable dust. Particle size was measured by laser particle analysis, morphology was observed by scanning electron microscope, chrysotile fiber phase was analyzed by X-ray diffraction, trace chemical elements were identified by X-ray fluorescence, and the structure and the active groups of the dust were determined after grinding by Fourier transform infrared spectroscopy. Male Wistar rats were exposed to non-exposed intratracheal instillation with different concentrations of chrysotile fiber dust. The rats were weighed after 1, 3, and 6xa0months, then the lung tissues were separated, the lung morphology was observed, and the pulmonary index was calculated. Pathological changes in lung tissues were observed by optical microscope after the HE staining of tissues, and the gene expression of p53 and p16 was determined by reverse transcription polymerase chain reaction. First, the results showed that the particle sizes of the four fibers were less than 10xa0μm. Four primary areas of chrysotile had similar fibrous structure, arranged in fascicles, or mixed with thin chunks of material. Second, the elementary composition of the four fibers was mainly chrysotile, and the structure and the active groups of the grinding dust were not damaged. Third, the weights of the treated rats were obviously lower, and the lung weights and the pulmonary index increased significantly (Pxa0<xa00.05). Fourth, the treated Wistar rat lung tissues revealed different degrees of congestion, edema, inflammatory cell infiltration, and mild fibrosis. Fifth, the p53 and p16 genes decreased in the Mangnai group after 1xa0month of exposure, and the other groups increased. The expression of p53 and p16 in each group decreased significantly after 6xa0months (Pxa0<xa00.05). In conclusion, the respirable chrysotile fiber dust from the four primary areas of China had the risk of causing lung injury, and these changes may be related to the physical and chemical characteristics of chrysotile from different production areas.

Chrysotile effects on the expression of anti-oncogene P53 and P16 and oncogene C-jun and C-fos in Wistar rats’ lung tissues

Chrysotile is the most widely used form of asbestos worldwide. China is the world’s largest consumer and second largest producer of chrysotile. The carcinogenicity of chrysotile has been extensively documented, and accumulative evidence has shown that chrysotile is capable of causing lung cancer and other forms of cancer. However, molecular mechanisms underlying the tumorigenic effects of chrysotile remained poorly understood. To explore the carcinogenicity of chrysotile, Wistar rats were administered by intratracheal instillation (by an artificial route of administration) for 0, 0.5, 2, or 8xa0mg/ml of natural chrysotile (from Mangnai, Qinghai, China) dissolved in saline, repeated once a month for 6xa0months (a repeated high-dose exposure which may have little bearing on the effects following human exposure). The lung tissues were analyzed for viscera coefficients and histopathological alterations. Expression of P53, P16, C-JUN, and C-FOS was measured by western blotting and qRT-PCR. Our results found that chrysotile exposure leads the body weight to grow slowly and lung viscera coefficients to increase in a dose-dependent manner. General sample showed white nodules, punctiform asbestos spots, and irregular atrophy; moreover, HE staining revealed inflammatory infiltration, damage of alveolar structures, agglomerations, and pulmonary fibrosis. In addition, chrysotile can induce inactivation of the anti-oncogene P53 and P16 and activation of the proto-oncogenes C-JUN and C-FOS both in the messenger RNA and protein level. In conclusion, chrysotile induced an imbalanced expression of cancer-related genes in rats’ lung tissue. These results contribute to our understanding of the carcinogenic mechanism of chrysotile.

Reciprocity Effect Between Silicate Bacterium and Wollastonite

This chapter studies the reciprocity effect between wollastonite and a strain of silicate bacterium isolated from purple soil. The changes of pH value, glucose (GLU) residual concentration, electrolyte, and Mn, Si, Fe, etc., in the culture liquid with wollastonite after 48 h were analyzed. The results show that the GLU consumption of silicate bacterium with wollastonite was 2.5 times of the bacterial control. It indicates that wollastonite can obviously promote silicate bacterium growth, but the silicate bacteria cells were badly broken and even distorted observed by SEM. The solubilization of Si element by silicate bacterium from wollastonite reached above ten times that of the wollastonite control. At the same time, three typical peak intensities in FTIR of wollastonite (898 cm−1, 925 cm−1, 962 cm−1) lowered obviously after the interaction with silicate bacterium, which shows that a great deal of Si has dissolved. Therefore, it is clear that wollastonite has a remarkable effect on the growth of silicate bacterium and there has been an obvious solubilization of Si.

The Study on Genotoxicity of PM 2.5 Mineral Dusts to A 549 Cells

Object: Detecting the influence of six main ingredients of PM2.5 mineral dusts on the A549 cell morphology, proliferation inhibition rate, micronuclei, and DNA damage to explore the genotoxicity of PM2.5 mineral dusts.

Cytotoxicity of Quartz and Montmorillonite in Human Lung Epithelial Cells (A549)

In this study, A549 cell viability, extracellular activities of lactate dehydrogenase (LDH), and tumor necrosis factor (TNF)-α and interleukin (IL)-6 levels were investigated after incubation with quartz (KWC-Q4 and KWC-Q3), Nano-SiO2, and KWC-M; the micronucleus test and comet assay were carried out to evaluate the genotoxicity. The results showed there were significant differences in the cell death rate and extracellular LDH activities compared with the control group, and showed a good linear relationship in certain concentration range. All mineral particles tested can induce the increase of TNF-α after incubation with mineral powders at 200 μg/mL for merely 3 h and also induce significant increase of IL-6 for 24 h; the results indicated that inflammatory reaction can be triggered by the exposure of KWC-Q4, KWC-Q3, Nano-SiO2, and KWC-M. The results of micronucleus test showed FMN (Frequency of micronucleus number) listed as Nano-SiO2>KWC-Q3>KWC-Q4. There was no significant FMN increase of KWC-M compared with the control group, which maybe resulted from its high cell mortality at low concentration. The comet assay confirmed the genotoxicity of all tested samples, and the DNA damage: KWC-M>Nano-SiO2>KWC-Q4>KWC-Q3.

Effect of Thermal Power Plant Dusts to the Growth of Some Body Normal Strains

This paper studied the growth effect mechanism of thermal power plant dust on three body normal flora. The physics properities, major chemical composition and granularity distributing of the experiment dust were analysis and the change of number of index bacterial colonies, pH, glucose (GLU) and electrolyte relative to the controls were observed. And in the same time, we studied the bacterial form and interface act in the action process of dusts and bacteria through SEM analysis. The reciprocity of thermal power dusts and three body normal strains didnt bring obvious change on the wastage of GLU, the number of bacterial colonies, pH value and the others electrolyte et al. Compare to the bacterial control groups, the concentrations of Ca2+ and Mg2+ increased 0.69mmol/L (P<0.05)and 0.16mmol/L (P<0.05) respectively. The bacteria colonies of Escherichia coli and Staphylococcus epidernidis increased 1×109 CFU/mL and 12×109 CFU/mL (P<0.05). Thermal power plant dusts of proper concentration have more obvious effect to the growth of Staphylococcus epidernidis than the other strains.