一种耐酚菌种及其固定化细胞降解含酚废水性能的比较研究

通过对土壤及污水的采样、分离、纯化,得到了一种降解苯酚的菌种,经过一系列驯化实验,使其苯酚耐受能力达915 mg/L。在此基础上,利用正交实验,确定了该菌种固定化细胞制备的最优操作条件。之后,对游离细胞和固定化细胞的降解苯酚过程进行了动力学分析与比较。结果表明,2种类型细胞的降解苯酚过程均符合Monod模型,并且固定化细胞的降解效果明显高于游离细胞。      

自絮凝颗粒酵母酒精连续发酵过程精馏废液循环回用工艺的研究

以玉米粉双酶法制备的糖化液为底物,采用酵母细胞自絮凝形成颗粒作为细胞固定化方法在有效容积１．５ Ｌ小型悬浮床生物反应器中研究了不同酒精精馏废液循环比条件下的连续发酵工艺过程,并探讨了酒精精馏废液“全循环”的可行性．研究结果表明：虽然产生了比较强的副产物抑制效应,但该工艺能够稳定操作,为酒精发酵行业彻底解决废液污染问题提供了一条简便、可行的工艺路线     

Studies on Formation of Liquid and Gaseous Formaldehyde-Induced DNA-Protein Crosslinks in Rat Marrow Cells

甲醛是一种遗传毒物,流行病学研究表明甲醛可能具有诱导白血病的作用,然而甲醛诱导白血病的机制目前还不清楚. 以不同浓度液态和气态甲醛对大鼠骨髓细胞进行染毒,采用KCl-SDS 法检测了骨髓细胞 DNA-蛋白质交联程度,并采用单细胞凝胶电泳技术(彗星实验)检测了骨髓细胞 DNA 链断裂程度. 研究结果表明:与对照组相比,低浓度甲醛(液态甲醛浓度为:5μmol·L-1和25μmol·L-1;气态甲醛浓度为:0.5mg·m-3 和 1.0mg·m-3)可以引起 DNA断裂水平显著增高 (p<0.01);而高浓度甲醛 (液态甲醛浓度为:125μmol·L-1 和 625μmol·L-1;气态甲醛浓度为:3.0mg·m-3)则可以引起 DNA-蛋白质交联水平显著增高(p<0.01; p<0.05). 研究结果提示:甲醛染毒可以导致大鼠骨髓细胞DNA的损伤,暗示甲醛诱导白血病具有高度的可能性.     

Scaling of dust explosion violence from laboratory scale to full industrial scale – A challenging case history from the past

The standardized K_St parameter still seems to be widely used as a universal criterion for ranking explosion violence to be expected from various dusts in given industrial situations. However, this may not be a generally valid approach. In the case of dust explosion venting, the maximum pressure P_max generated in a given vented industrial enclosure is not only influenced by inherent dust parameters (dust chemistry including moisture, and sizes and shapes of individual dust particles). Process-related parameters (degree of dust dispersion, cloud turbulence, and dust concentration) also play key roles. This view seems to be confirmed by some results from a series of large scale vented dust explosion experiments in a 500 m³ silo conducted in Norway by CMI, (now GexCon AS) during 1980–1982. Therefore, these results have been brought forward again in the present paper. The original purpose of the 500 m³ silo experiments was to obtain correlations between P_max in the vented silo and the vent area in the silo top surface, for two different dusts, viz. a wheat grain dust collected in a Norwegian grain import silo facility, and a soya meal used for production of fish farming food. Both dusts were tested in the standard 20-L-sphere in two independent laboratories, and also in the Hartmann bomb in two independent laboratories. P_max and (dP/dt)_max were significantly lower for the soya meal than for the wheat grain dust in all laboratory tests. Because the available amount of wheat grain dust was much larger than the quite limited amount of available soya meal, a complete series of 16 vented silo experiments was first performed with the wheat grain dust, starting with the largest vent area and ending with the smallest one. Then, to avoid unnecessary laborious changes of vent areas, the first experiment with soya dust was performed with the smallest area. The dust cloud in the silo was produced in exactly the same way as with the wheat grain dust. However, contrary to expectations based on the laboratory-scale tests, the soya meal exploded more violently in the large silo than the wheat grain dust, and the silo was blown apart in the very first experiment with this material. The probable reason is that the two dusts responded differently to the dust cloud formation process in the silo on the one hand and in the laboratory-scale apparatuses on the other. This re-confirms that a differentiated philosophy for design of dust explosion vents is indeed needed. Appropriate attention must be paid to the influence of the actual dust cloud generation process on the required vent area. The location and type of the ignition source also play important roles. It may seem that tailored design has to become the future solution for tackling this complex reality, not least for large storage silos. It is the view of the present author that the ongoing development of CFD-based computer codes offers the most promising line of attack. This also applies to design of systems for dust explosion isolation and suppression.     

Cardiotoxin III suppresses the invasiveness of MDA-MB-231 cells by targeting proto-oncogene tyrosine-protein kinase Src and reversing mesenchymal-to-epithelial transition

The epithelial-to-mesenchymal transition is the first step required for breast cancer to initiate metastasis. The aberrant activation of proto-oncogene tyrosine-protein kinase Src regulates multiple functions during tumor progression. Cardiotoxin III, a basic polypeptide isolated from Naja naja atra venom, has been shown to exhibit anticancer activity; however, the effect of cardiotoxin III on the epithelial-to-mesenchymal transition of cancer cells remains elusive. Exposure of MDA-MB-231 cells to cardiotoxin III resulted in morphological changes and upregulation of E-cadherin with a concomitant decrease in N-cadherin and vimentin protein levels, resulting in the inhibition of cell migration and invasion. Cardiotoxin III induced downregulation of snail and slug expression. Simultaneously, cardiotoxin III suppressed Src phosphorylation and downstream activation of focal adhesion kinase, of the docking protein p130^cas, and of paxillin. In addition, cardiotoxin III inhibited the phosphorylation of extracellular signal-regulated kinase and phosphatidylinositol 3-kinase. The Src specific inhibitor 4-amino-5-(4-chlorophenyl)-7-(dimethylethyl)pyrazolo[3,4-d]pyrimidine decreased in the phosphorylation and the expression changes of epithelial-to-mesenchymal transition markers in a similar way. Thus, cardiotoxin III has a novel anticancer effect by suppressing proto-oncogene tyrosine-protein kinase activity, reversing epithelial-to-mesenchymal transition.     

Oxidative stress in the blood of pregnant rats and reduction of organ weights caused by the polychlorinated biphenyl congener 77

3,3′,4,4′-Tetrachlorobiphenyl (PCB 77), one of the environmentally persistent polychlorinated biphenyls that have been used for industrial purposes, was repeatedly administered to pregnant rats by gavage at a dose of minimal, non-lethal toxicity in order to study its effects on routine blood variables, parameters of oxidative stress and hematopoietic organs in pregnant female rats. Of the routine blood parameters, PCB 77 reduced the mean corpuscular hemoglobin concentration and platelet counts; the levels of malondialdehyde and glutathione peroxidase in the blood were higher during the first days of gestation (1–7), as compared to the respective controls. In the subsequent period between days 8 and 18, these parameters did not show any significant change after PCB 77 treatment. Routine blood parameters and oxidative stress parameters indicated a moderate degree of oxidative stress which alone could not bring about the serious weight reduction of the thymus, pituitary, and kidneys. The extent of oxidative stress did not correlate with the weight reduction of some of the blood-forming organs.     

Protective influence of antioxidant vitamins on hematological indices of rabbits fed crude-oil-contaminated diet

The effects of chronic exposure to petroleum on hematological parameters as well as the possible protective role of vitamins E and C were studied. The hematological parameters assessed were red blood cell (RBC) counts, hematocrit, hemoglobin concentration, and white blood cell (WBC) counts. The RBC and hemoglobin concentration were significantly decreased in the blood of petroleum-fed rabbits. However, there was a significant increase in WBC in rabbits exposed to crude-oil-contaminated feed. Pretreatment with the antioxidant vitamins E and C restored these parameters to normal.     

Effects of arsenic exposure during early postnatal period on Leydig cells of rat testis

The effects of sodium arsenite exposure from postnatal day (PND) 1 to PND 14 on Leydig cells of Wistar rat testes were investigated at PND 15 and 21. Gross morphometric observations of testes did not reveal a significant change in the numerical density and volume of the testes in exposed animals compared to controls either at PND 15 or 21. However, there was significant decrease in testicular weight at PND 21 in treated animals. Measurement of nuclear area of Leydig cells revealed a decrease in nuclear area of these cells in exposed groups at PND 15 and 21. A significant decrease in the total number of Leydig cells was apparent at PND 21 in the treated group. The observations of the present study are indicative of adverse effects on rat testes Leydig cells following exposure to low doses of sodium arsenite during critical window periods. The persistence of these observations at PND 21 is suggestive of irreversible damage to testicular tissue.     

Cytotoxic and apoptotic activity of Scrophularia oxysepala in MCF-7 human breast cancer cells

Breast cancer is the most common cancer in women. Therefore, there is an urgent need to identify and develop therapeutic strategies against this deadly disease. This study is the first to investigate the cytotoxic and apoptotic effects of Scrophularia oxysepala in MCF-7 human breast cancer cells. Dichloromethane, methanol and n-hexane extracts of Scrophularia oxysepala were examined. The 3-(4,5-dimethylethiazol-2-yl)-2,5-diphenyltetrazolium (MTT) reduction and trypan-blue exclusion assays were performed in MCF-7 cells as well as control cell line MCF10A to analyze the cytotoxic activity of the plant. Furthermore, the apoptosis-inducing action of extracts of the plant was evaluated using cell death detection ELISA, the terminal deoxynucleotide transferase dUTP nick end labeling (TUNEL) assay, Western blotting and real-time polymerase chain reaction (PCR). The results showed that dichloromethane and methanol extracts significantly inhibited cell growth and viability without inducing damage to MCF10A cells. Cell death detection ELISA, morphological changes of cells in TUNEL assay, Western blot detection of poly (ADP-ribose) polymerase (PARP) cleavage and increase in the mRNA expression levels of p-53, caspase-3 and c-myc showed that the induction of apoptosis was the main mechanism of cell death. Our results strongly suggest that this plant may contain potential bioactive compound(s) for the treatment of breast cancer.     

Characterization and in vitro biological effects of ambient air PM10 from a rural,an industrial and an urban site in Sulaimani City,Iraq

Abstract

High urban atmospheric pollution is caused by economic and industrial growth, especially in developing countries. The objective of this study was to assess possible relationships between in vitro effects on human alveolar epithelial cells of source-related dust types collected at Sulaimani City (Iraq), and to determine their mineralogical and chemical composition. A passive sampler was used to collect dust particles at a rural, an industrial and an urban sampling site during July and August 2014. The samples were size-fractionated by a low-pressure impactor to obtain respirable dust with aerodynamic diameters of less than 10?µm. The dust was mainly composed of quartz and calcite. Chrysotile fibers (white asbestos) were also found at the urban site. Dust from the industrial and urban sites triggered cytotoxic and genotoxic effects in the cells, whereas only minor effects were observed for the sample from the rural site.