Diesel degradation capability and environmental robustness of strain Pseudomonas aeruginosa WS02.

Petroleum hydrocarbon (PHC) degrading bacteria have been frequently discovered. However, in practical application, a single species of PHC degrading bacterium with weak competitiveness may face environmental pressure and competitive exclusion due to the interspecific competition between petroleum-degrading bacteria as well as indigenous microbiota in soil, leading to a reduced efficacy or even malfunction. In this study, the diesel degradation ability and environmental robustness of an endophytic strain Pseudomonas aeruginosa WS02, were investigated. The results show that the cell membrane surface of WS02 was highly hydrophobic, and the strain secreted glycolipid surfactants. Genetic analysis results revealed that WS02 contained multiple metabolic systems and PHC degradation-related genes, indicating that this strain theoretically possesses the capability of oxidizing both alkanes and aromatic hydrocarbons. Gene annotation also showed many targets which coded for heavy metal resistant and metal transporter proteins. The gene annotation-based inference was confirmed by the experimental results: GC-MS analysis revealed that short chain PHCs (C10-C14) were completely degraded, and the degradation of PHCs ranging from C15-C22 were above 90% after 14 d in diesel-exposed culture; Heavy metal (Mn2+, Pb2+ and Zn2+) exposure was found to affect the growth of WS02 to some extent, but not its ability to degrade diesel, and the degradation efficiency was still maintained at 39-59%. WS02 also showed a environmental robustness along with PHC-degradation performance in the co-culture system with other bacterial strains as well as in the co-cultured system with the indigenous microbiota in soil fluid extracted from a PHC-contaminated site. It can be concluded that the broad-spectrum diesel degradation efficacy and great environmental robustness give P. aeruginosa WS02 great potential for application in the remediation of PHC-contaminated soil.

The Anti-Sepsis Effect of Isocorydine Screened from Guizhou Ethnic Medicine is Closely Related to Upregulation of Vitamin D Receptor Expression and Inhibition of NFκB p65 Translocation into the Nucleus.

Background: The anti-inflammatory application of Guizhou ethnic medicine in the Karst area of China is mainly based on folk medicine experience, and there has been a lack of systematic research, leading to limited application of Guizhou ethnic medicine. Purpose: To evaluate the anti-inflammatory effects of compounds extracted from Guizhou ethnic medicine in the Karst area and investigate their molecular mechanisms. Methods and Results: Preliminarily, the anti-inflammatory effects of 181 compounds extracted from Guizhou ethnic medicine were screened in lipopolysaccharide (LPS)-stimulated peritoneal macrophages and the 41 compounds with anti-inflammatory effects were selected. Then, these 41 compounds with anti-inflammatory effects were investigated for their druggability and 18 compounds were selected. Thirdly, compound Hx-150, named isocorydine, was selected as the candidate compound. In vitro and in vivo, isocorydine inhibited LPS-induced TNF-α and IL-6 release from LPS-treated mouse peritoneal macrophages. Isocorydine decreased TNF-α, IL-6, and IL-1ß levels in the blood, lung, and spleen, and ameliorated lung tissue damage. Mechanistically, isocorydine had no effect on the mRNA expressions and protein levels of Tlr4, Myd88, and Traf6. Isocorydine also had no effect on the expression of RelA (encoding NFκB p65) mRNA, but inhibited phosphorylation of IκBα and NFκB p65 in the TLR4-mediated signaling pathway. Furthermore, isocorydine increased the cytoplasmic level of NFκB p65 and decreased its nuclear level in LPS-treated macrophages. Importantly, isocorydine upregulated Vdr mRNA (encoding the vitamin D receptor) expression and increased the nuclear VDR protein level. Conclusion: Many compounds from Guizhou ethnic medicine had potential anti-inflammatory activities. Among them, isocorydine has a strong anti-sepsis effect, which is tightly related to its upregulation of VDR expression and inhibition of NFκB p65 translocation into the nucleus, leading to reduced pro-inflammatory cytokines release and protection for LPS-challenged mice.

Effects of natural dihydrochalcones in sweet tea (Lithocarpus polystachyus) on diabetes: a systematical review and meta-analysis of animal studies.

Sweet tea (Lithocarpus polystachyus Rehd.), a natural functional food highly rich in dihydrochalcones including trilobatin, phlorizin and phloretin, is reported to possess numerous biological activities especially for treating diabetes. Here, the aim of this systematical review and meta-analysis is to assess the effect of dihydrochalcones in sweet tea (DST) on diabetes and summarize their possible mechanisms. We searched in eight databases including Embase, PubMed, Cochrane, Web of Science, WanFang database, VIP database, China National Knowledge Infrastructure and China Biology Medicine from Jan 2000 to Nov 2021 and ultimately included 21 animal studies in this review. A total of 10 outcome measurements including blood lipid indexes, blood glucose, insulin resistance indicators and oxidative stress biomarkers were extracted for meta-analysis using RevMan 5.4 software. DST significantly decreased the levels of triglyceride (TG), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-c), blood glucose (BG), homeostasis model assessment of insulin resistance (HOMA-IR) and malondialdehyde (MDA), and increased high-density lipoprotein cholesterol (HDL-c), superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activity in diabetic animal models. In summary, DST could treat diabetes by regulation of blood glucose/lipid metabolism, oxidative/carbonyl stress, inflammatory response etc.

The Change in the Structure and Functionality of Ferritin during the Production of Pea Seed Milk.

Understanding the effect of thermal treatment on the physical and chemical properties of protein and its mechanisms has important theoretical implications in food science. Pea seed ferritin (PSF) is an iron storage protein naturally occurring in pea seeds, which represents a promising iron supplement. However, how thermal processing affects the structure and function of PSF remains unknown. In this work, during the production of pea seed milk, we investigated the effect of thermal treatments at boiling temperature for two different times (5 and 10 min), respectively, on the structure and function of PSF. The results demonstrated that thermal treatment resulted in a pronounced change in the primary, secondary, and tertiary structure, iron content, and iron oxidation activity of PSF. However, the shell-like structure of PSF can be kept during the processing of pea seed milk. Interestingly, upon thermal treatment, both thermal-treated samples exhibit larger higher iron absorption rate by Caco-2 than untreated PSF at the same protein concentration. Such an investigation provides a better understanding of the relationship between the structure and function of food protein, as affected by thermal treatment.

Weak Binding of Epigallocatechin to α-Lactalbumin Greatly Improves Its Stability and Uptake by Caco-2 Cells.

Improving the stability and bioavailability of catechins is of great importance. Epigallocatechin (EGC), the major catechin in green tea, is a potent antioxidant with numerous attributed health benefits. However, the low permeability and stability limit its enrichment in the diet for preventive medicine. In this study, we explored the interaction of EGC and α-lactalbumin by spectroscopic, thermodynamic, and crystallographic methods. The isothermal titration calorimetry experiments elucidated that α-lactalbumin binds to EGC at a ratio of 1:1 with a low affinity of (4.01 ± 0.11) × 105 M-1. A crystal structure solved at a high resolution (1.2 Å) provided direct evidence for the weak interaction between EGC and α-lactalbumin at an atomic level. The novel binding site was discovered at the exterior surface of α-lactalbumin for the first time, supporting a new binding behavior. Consequently, our results demonstrated that the binding of α-lactalbumin to EGC could protect EGC against light-induced, thermal-induced, and pH-induced damage. More importantly, the formed complex has better bioaccessibility than unbound EGC, which was approved by a cell absorption experiment. Such research is beneficial for designing protein-based nanocarriers for polyphenols.

Changes in physicochemical properties and microfauna community during vermicomposting of municipal sludge under different moisture conditions.

The present study aimed to explore the effect of a range of moisture content levels, including 65%, 72%, and 78%, on physicochemical properties and microfauna communities during vermicomposting of municipal sludge. As a result, death of perishable microfauna together with the degradation of organic matter was the dominant response in all groups in the early period of vermicomposting, while the effects of moisture content levels on various physiochemical parameters did not appear until the mid-later period. After the treatment with 78% moisture content, the content of mineral nitrogen was 1.186 g/kg in the sludge, with a 9.36 × 103 ind./g of microfauna quantity and 663.01 g of earthworm biomass. The values of these three measurements in 78% group were significantly higher than other two groups (p < 0.05), indicating that the effects of 78% moisture content were more pronounced for promoting nitrogen mineralization as well as microfauna and earthworms growth during vermicomposting. Specifically, testate amoebae were strongly associated with nitrification process, while nematodes were related to ammonification and phosphorus mineralization, of which testate amoebae had great potential of being bioindicators during vermicomposting of municipal sludge.

N-(3-Methozybenzyl)-(9Z,12Z,15Z)-octadecatrienamide from maca (Lepidium meyenii Walp.) ameliorates corticosterone-induced testicular toxicity in rats.

This study investigated the protective effects of maca ethanol extract (EEM) and N-(3-methozybenzyl)-(9Z,12Z,15Z)-octadecatrienamide (M 18:3) on corticosterone (CORT)-induced testicular toxicity. Male Wistar rats were divided into 5 groups. Except for the control group, CORT (40 mg per kg·bw) was injected subcutaneously for 21 consecutive days to induce testicular toxicity. 1 h before CORT injection, the rats were treated with EEM (400 mg per kg·bw) and M 18:3 (5 mg per kg·bw, 25 mg per kg·bw) by gavage, except for the control group and model group. Epididymal sperm and biochemical, and histological parameters were evaluated for the protective effects of the drugs. EEM (400 mg per kg·bw) and M 18:3 (5 mg per kg·bw, 25 mg per kg·bw) increased the sperm concentration and sperm motility, decreased the production of abnormal sperms, and increased the number of spermatogonia and primary spermatocytes in the seminiferous tubules of CORT-induced rats. Moreover, EEM and M 18:3 decreased the MDA levels and the positive expression rates of TUNEL, whereas they increased the activities of SOD, CAT, GSH-Px, and GST, and the contents of GSH in the testicles of CORT-induced rats. Furthermore, EEM and M 18:3 alleviated CORT-induced reduction in the positive expression rates of PCNA and Ki67 in the testicles of rats. Besides, EEM and M 18:3 reduced the expression levels of Keap-1 and increased the expression levels of Nrf2, HO-1, γ-GCS, and NQO1 in the testicles of CORT-induced rats. In summary, the protective effects of EEM and M 18:3 may be attributed to their anti-oxidative and anti-apoptotic properties.

Aerial parts of maca (Lepidium meyenii Walp.) as functional vegetables with gastrointestinal prokinetic efficacy in vivo.

Lepidium meyenii Walp. (maca) has been utilized in the Andean region because of its edibleness and medicinal value. The aerial parts of maca (APM) were analyzed for protein, total sugar, vitamins, amino acids, and minerals and its characteristic active ingredients at five different growth stages. The results showed the high protein, total sugar, vitamin C, niacin, potassium, and calcium contents of APM. All 17 amino acids and the characteristic active ingredients, namely, macamide, glucosinolates, adenosine, and total saponins, were detected. We examined the effects of maca plant powders on gastric emptying and intestinal propulsion and the levels of serum motilin and gastrin in atropine-treated mice. Benzyl isothiocyanate (BITC) was investigated to identify the potential active material in APM. The results revealed that both maca plant powders and BITC can promote the gastrointestinal prokinetic efficacy. Thus, APM feature potential as new functional vegetable sources.

Sequence-Based Prediction of Cysteine Reactivity Using Machine Learning.

As one of the most intrinsically reactive amino acids, cysteine carries a variety of important biochemical functions, including catalysis and redox regulation. Discovery and characterization of cysteines with heightened reactivity will help annotate protein functions. Chemical proteomic methods have been used to quantitatively profile cysteine reactivity in native proteomes, showing a strong correlation between the chemical reactivity of a cysteine and its functionality; however, the relationship between the cysteine reactivity and its local sequence has not yet been systematically explored. Herein, we report a machine learning method, sbPCR (sequence-based prediction of cysteine reactivity), which combines the basic local alignment search tool, truncated composition of k-spaced amino acid pair analysis, and support vector machine to predict cysteines with hyper-reactivity based on only local sequence features. Using a benchmark set compiled from hyper-reactive cysteines in human proteomes, our method can achieve a prediction accuracy of 98%, a precision of 95%, and a recall ratio of 89%. We utilized these governing features of local sequence motifs to expand the prediction to potential hyper-reactive cysteines in other proteomes deposited in the UniProt database. We validated our predictions in Escherichia coli by activity-based protein profiling and discovered a hyper-reactive cysteine from a functionally uncharacterized protein, YecH. Biochemical analysis suggests that the hyper-reactive cysteine might be involved in metal binding. Our computational method provides a large inventory of potential hyper-reactive cysteines in proteomes and is highly complementary to other experimental approaches to guide systematic annotation of protein functions in the postgenome era.

Earthworms facilitate the stabilization of pelletized dewatered sludge through shaping microbial biomass and activity and community.

In this study, the effect of earthworms on microbial features during vermicomposting of pelletized dewatered sludge (PDS) was investigated through comparing two degradation systems with and without earthworm E isenia fetida involvement. After 60 days of experimentation, a relatively stable product with low organic matter and high nitrate and phosphorous was harvested when the earthworms were involved. During the process, earthworms could enhance microbial activity and biomass at the initial stage and thus accelerating the rapid decomposition of PDS. The end products of vermicomposting allowed the lower values of bacterial and eukaryotic densities comparison with those of no earthworm addition. In addition, the presence of earthworms modified the bacterial and fungal diversity, making the disappearances of some pathogens and specific decomposing bacteria of recalcitrant substrates in the vermicomposting process. This study evidences that earthworms can facilitate the stabilization of PDS through modifying microbial activity and number and community during vermicomposting.

[Treatment of Petrochemical Treatment Plant Secondary Effluent by Fenton Oxidation].

Fenton oxidation was applied to treat the petrochemical treatment plant secondary effluent by the continuous flow configuration. The effect of Fenton agent dosage on the COD and phosphorus removal and the variation of the dissolved organic matter characteristics during the treatment process were investigated. The results showed the average COD and PO(4)3- -P concentrations were 64.8 mg.L-1 and 0. 79 mg.L-1, respectively. When the dosage of H2O (30%), FeSO4.7H2O and PAM were 0. 4 mL.L-1, 0. 8 mg.L-1 and 0. 9 mg.L-1 and the residence time was 30 min, the average removal rate of COD and PO(4)3- -P were 24. 3% and 95. 5% respectively. The effluent COD was lower than 50 mg.L-1. The percentage of dissolved organic matters with molecular weight less than 1 x 10(3) was 80. 4% in the raw wastewater, however, the percentage increased to 95. 6% when treated by Fenton oxidation. Three-dimensional fluorescence analysis showed that the Fenton oxidation can effectively remove protein and phenols. GC-MS results showed that there were about 117 kinds of organic matters detected in the secondary effluent, while the number reduced to 27 after oxidation by Fenton. The organics containing unsaturated bond had a better removal than those of other types of organics. Fenton oxidation can be used in the advanced treatment of petrochemical secondary effluent.

White-light-exciting, layer-by-layer-assembled ZnCdHgSe quantum dots/polymerized ionic liquid hybrid film for highly sensitive photoelectrochemical immunosensing of neuron specific enolase.

ZnCdHgSe quantum dots (QDs) functionalized with N-acetyl-l-cysteine were synthesized and characterized. Through layer-by-layer assembling, the ZnCdHgSe QDs was integrated with a polymerized 1-decyl-3-[3-pyrrole-1-yl-propyl]imidazolium tetrafluoroborate (PDPIT) ionic liquid film modified indium tin oxide (ITO) electrode to fabricated a photoelectrochemical interface for the immobilization of rabbit antihuman neuron specific enolase (anti-NSE). After being treated with glutaraldehyde vapor and bovine serum albumin successively, an anti-NSE/ZnCdHgSe QDs/PDPIT/ITO sensing platform was established. Simplely using a white-light LED as an excitation source, the immunoassay of neuron specific enolase (NSE) was achieved through monitoring the photocurrent variation. The polymerized ionic liquid film was demonstrated to be an important element to enhance the photocurrent response of ZnCdHgSe QDs. The anti-NSE/ZnCdHgSe QDs/PDPIT/ITO based immunosensor presents excellent performances in neuron specific enolase determination. The photocurrent variation before and after being interacted with NSE exhibits a good linear relationship with the logarithm of its concentration (log cNSE) in the range from 1.0 pg mL(-1) to 100 ng mL(-1). The limit of detection of this immunosensor is able to reach 0.2 pg mL(-1) (S/N = 3). The determination of NSE in clinical human sera was also demonstrated using anti-NSE/ZnCdHgSe QDs/PDPIT/ITO electrode. The results were found comparable with those obtained by using enzyme-linked immunosorbent assay method.

Feasibility of vermistabilization for fresh pelletized dewatered sludge with earthworms Bimastus parvus.

The aim of this study was to investigate the feasibility of vermistabilization of fresh pelletized dewatered sludges (PDS) without any bulking materials using earthworms Bimastus parvus. For this, two pelletized treatments with 4.5mm and 14.5mm fresh PDS and one without pelletized treatment were setup. Earthworm's fate test showed that earthworms could not survive in the treatment without pelletisation. For two pelletized treatments, B. parvus had a good life, producing great numbers of cocoons and hatchlings, after 60days. Vermicomposting of PDS resulted in the decreases of DOC, ammonia-nitrogen and microbial biomass and activity while increases of electrical conductivity and nitrate-nitrogen and available phosphorous. These findings suggest the stable and beneficial vermicomposts were achieved. The overall results evidenced that the fresh PDS without blending could be directly stabilized by vermicomposting and the vermireactor containing 4.5mm PDS displayed a better performance than 14.5mm PDS.

Telomerase activity and telomerase reverse transcriptase expression induced by selenium in rat hepatocytes.

OBJECTIVE: To investigate the effects of sodium selenite on telomerase activity, apoptosis and expression of TERT, c-myc and p53 in rat hepatocytes. METHODS: Selenium at doses of 2.5, 5.0, and 10 micromol/kg was given to SD rats by gavage. In rat hepatocytes, telomerase activity was measured by the telomeric repeat amplification protocol (TRAP), apoptosis was detected by flow cytometry, and expressions of telomerase reverse transcriptase (TERT), c-myc and p53 were analyzed by reverse transcription-polymerase chain reaction (RT-PCR). c-Myc and P53 proteins were detected by immunochemistry. RESULTS: Selenium at doses of 2.5, 5.0, and 10 micromol/kg significantly increased hepatocellular telomerase activity and induced apoptosis in a dose-dependent manner. Although selenium at doses of 2.5, 5.0, and 10 micromol/kg displayed no obvious enhancing effect on the TERT mRNA expression in rat hepatocytes (P > 0.05), it significantly increased the c-myc mRNA and p53 mRNA expression at the dose of 10 micromol/kg (P < 0.05). Selenium at doses of 5.0 and 10 micromol/kg obviously increased the content of P53 protein in rat hepatocytes, but only at the dose of 10 micromol/kg, it significantly promoted the value of c-Myc protein in them. CONCLUSION: Selenium can slightly increase telomerase activity and TERT expression, and significantly induce apoptosis and over-expression of c-myc and p53 at relatively high doses. The beneficial effects of selenium on senescence and aging may be mediated by telomerase activation and expression of TERT, c-myc, and p53 in rat hepatocytes.

[Effects of earthworm (Eisennia foetida ) on As, P uptake by maize and As, P fractional transformation in the rhizosphere].

A pot experiment was conducted to examine the roles of earthworm in As uptake from original As-polluted soil by maize (Zea mays L.), and their effects on As, P fractions in the rhizosphere. The As-polluted soils with three As levels were collected from the arable soil near As mine. The plants were harvested after 10 weeks of growth. Dry weight (DW) and P, As concentrations of plants, as well as As and P fractions of the rhizospheric soil, were determined. The results showed that inoculated earthworm or appended rice straw increased maximal 149%, 222% DW of root and shoot, respectively. At the medium and high soil As levels, root As concentration in the soil treated by earthworm and rice straw was highest among all treatments, and earthworm increased more As concentration of shoot than rice straw did. In different soil As levels, root P concentration in the soil treated by earthworm was highest, and shoot P by rice straw. Ca-P affected maize absorbing As at the low soil As level(r = 0.981), and maize absorbing Al-P was restrained by As involved in well-crystallized hydrous oxides of Fe and Al at the medium (r = 0.953)and high (r = 0.997)soil As levels. The concentration of non-specially absorbed As and As combined with Fe or Al and of O-P increased at the soil inoculated earthworm or/and appended rice straw at the same time. These results indicated that earthworm was more valuable for plant developing than rice straw was.

DNA damage, apoptosis and C-myc, C-fos, and C-jun overexpression induced by selenium in rat hepatocytes.

OBJECTIVE: To study the effects of selenium on DNA damage, apoptosis and c-myc, c-fos, and c-jun expression in rat hepatocytes. METHODS: Sodium selenite at the doses of 5, 10, and 20 micromol/kg was given to rats by i.p. and there were 5 male SD rats in each group. Hepatocellular DNA damage was detected by single cell gel electrophoresis (or comet assay). Hepatocellular apoptosis was determined by TUNEL (TdT-mediated dUTP nick end labelling) and flow cytometry. C-myc, c-fos, and c-jun expression in rat hepatocytes were assayed by Northern dot hybridization. C-myc, c-fos, and c-jun protein were detected by immunohistochemical method. RESULTS: At the doses of 5, 10, and 20 micromol/kg, DNA damage was induced by sodium selenite in rat hepatocytes and the rates of comet cells were 34.40%, 74.80%, and 91.40% respectively. Results also showed an obvious dose-response relationship between the rates of comet cells and the doses of sodium selenite (r=0.9501, P<0.01). Sodium selenite at the doses of 5, 10, and 20 micromol/kg caused c-myc, c-fos, and c-jun overexpression obviously. The positive brown-yellow signal for proteins of c-myc, c-fos, and c-jun was mainly located in the cytoplasm of hepatocytes with immunohistochemical method. TUNEL-positive cells were detected in selenium-treated rat livers. Apoptotic rates (%) of selenium-treated liver cells at the doses of 5, 10, and 20 micromol/kg were (3.72 +/- 1.76), (5.82 +/- 1.42), and (11.76 +/- 1.87) respectively, being much higher than those in the control. Besides an obvious dose-response relationship between apoptotic rates and the doses of sodium selenite (r=0.9897, P<0.01), these results displayed a close relationship between DNA damage rates and apoptotic rates, and the relative coefficient was 0.9021, P<0.01. CONCLUSION: Selenium at 5-20 micromol/kg can induce DNA damage, apoptosis, and overexpression of c-myc, c-fos, and c-jun in rat hepatocytes.

[Effects of selenium on expression of TERT, c-Myc and p53 induced by cadmium in rat liver].

OBJECTIVE: To study the effects of sodium selenite on expression of telomerase reverse transcriptase mRNA, c-Myc and p53 induced by cadmium chloride in rat liver. METHODS: Male SD rats were divided randomly into 6 groups, each group had 5 animals. The groups comprised the control group, Se group (5 micromol/kg sodium selenite), 5 micromol/kg cadmium chloride group, 10 micromol/kg cadmium chloride group, Se (5 micromol/kg sodium selenite) + 5 micromol/kg cadmium chloride group, Se (5 micromol/kg sodium selenite) + 10 micromol/kg cadmium chloride group. After 48 hours of the first injection, the expression of TERT mRNA was measured with RT-PCR and c-Myc, and p53 proteins were measured by immunohistochemistry method. RESULTS: Compared with control group, the expression of TERT was increased in 5 micromol/kg Cd group and 10 micromol/kg Cd group, c-Myc protein was increased in 10 micromol/kg Cd group, and the expression of p53 protein was increased in 5 micromol/kg group and 10 micromol/kg Cd group. TERT expression in Se + 10 micromol/kg Cd group was lower than that of 10 micromol/kg Cd group significantly. c-Myc protein was decreased in Se + 10 micromol/kg Cd group compared with 10 micromol/kg Cd group. p53 protein of Se + 5 micromol/kg Cd group and Se + 10 micromol/kg Cd group were decreased significantly compared with 5 micromol/kg Cd group and 10 micromol/kg Cd group respectively. CONCLUSION: The cadmium at the doses of between 5 and 10 micromol/kg can activate TERT and up-regulate c-Myc and p53 proteins. The selenium at the dose of 5 micromol/kg has the antagonistic effect on expression of TERT, c-Myc and p53 induced by cadmium in rat liver.

Effects of selenium and zinc on renal oxidative stress and apoptosis induced by fluoride in rats.

OBJECTIVE: To study the effects of selenium and zinc on oxidative stress, apoptosis, and cell cycle changes in rat renal cells induced by fluoride. METHODS: Wistar rats were given distilled water containing sodium fluoride (50 mg/L NaF) and were gavaged with different doses of selenium-zinc preparation for six months. Four groups were used and each group had eight animals (four males and four females). Group one, sham-handled control; group two, 50 mg/L NaF; group three, 50 mg/L NaF with a low dose of selenium-zinc preparation (0.1 mg/kg Na2 SeO3 and 14.8 mg/kg ZnSO4 x 7H2O); and group four, 50 mg/L NaF with a high dose of selenium-zinc preparation (0.2 mg/kg Na2 SeO3 and 29.6 mg/kg ZnSO4 x 7H2O). The activities of serum glutathione peroxidase (GSH-Px), kidney superoxide dismutase (SOD), and the levels of malondialdehyde (MDA) and glutathione (GSH) in the kidney were measured to assess the oxidative stress. Kidney cell apoptosis and cell cycle were detected by flow cytometry. RESULTS: NaF at the dose of 50 mg/L increased excretion of fluoride in urine, promoted activity of urine gamma-glutamyl transpeptidase (gamma-GT), inhibited activity of serum GSH-PX and kidney SOD, reduce kidney GSH content, and increased kidney MDA. NaF at the dose of 50 mg/L also induced rat renal apoptosis, reduced the cell number of G2/M phase in cell cycle, and decreased DNA relative content significantly. Selenium and zinc inhibited effects of NaF on oxidative stress and apoptosis, promoted the cell number of G2/M phase in cell cycle, but failed to increase relative DNA content significantly. CONCLUSION: Sodium fluoride administered at the dose of 50 mg/L for six months induced oxidative stress and apoptosis, and changes the cell cycle in rat renal cells. Selenium and zinc antagonize oxidative stress, apoptosis, and cell cycle changes induced by excess fluoride.

[Effects of selenium on rat hepatocellular DNA damage induced by cadmium in vitro].

OBJECTIVES: This study was conducted to explore effects of selenium on rat hepatocellular DNA damage induced by cadmium in vitro. METHOD: Sodium selenite was added at concentrations of 8.75, 17.50 and 35.00 micromol/L respectively with cadmium chloride at the concentrations of 8.75, 17.50 and 35.00 micromol/L respectively and rat hepatocellular DNA damage was measured with single cell gel electrophoresis (comet assay). RESULTS: Sodium selenite at the concentration of 8.75 micromol/L inhibited DNA damage caused by cadmium chloride at the concentration of 8.75, 17.50 and 35.00 micromol/L in rat liver cells (P < 0.05). Although sodium selenite at 17.50 micromol/L inhibited DNA damage induced by cadmium chloride at 17.50 and 35.00 micromol/L, it did not inhibit DNA damage induced by cadmium chloride at 8.75 micromol/L. Sodium selenite at 35.00 micromol/L did not have antagonistic effects on DNA damage induced by cadmium chloride at 8.75, 17.50 and 35.00 micromol/L. In addition, sodium selenite at 8.75 micromol/L had the best antagonistic effect while cadmium chloride at 8.75 micromol/L, but the antagonistic effect of sodium selenite at 17.50 micromol/L was better than 8.75 micromol/L while cadmium chloride at 17.50 and 35.00 micromol/L. CONCLUSION: The antagonistic effect of selenium on rat hepatocellular DNA damage induced by cadmium related to the concentrations of selenium and also to the concentration ratio between selenium and cadmium.

[Effects of selenium on benzo[a] pyrene-induce DNA damage in mouse lung cells].

OBJECTIVE: To explore the effects of selenium on DNA damage induced by benzo[a] pyrene (BaP) in mouse lung cells. METHODS: Sodium selenite was given to Kunming male mice by i.p. and BaP was given by oral gavage. The control group was given solvent only with the same method. DNA damage was detected by single cell gel electrophoresis (or comet assay). RESULTS: The damage degrees in mice treated with 125, 250 and 500 mg/kg of BaP were more severe than that of control (P < 0.01). The rates of comet cells in the BaP-treated groups (43.50%, 84.00%, 95.63%) were significantly higher than that of control (9.75%, P < 0.01), and there was obvious dose-response relationship. 0.75, 1.50 and 3.00 mg/kg of sodium selenite presented antagonistic effects against DNA damage induced by 250 mg/kg of BaP in mouse's lung cells. The antagonistic effect of sodium selenite at the dose of 1.50 mg/kg was better than those of sodium selenite at the doses of 0.75, 3.00 mg/kg. CONCLUSION: BaP at the doses of 125 approximately 500 mg/kg could significantly induce DNA damage of lung cells in mice. 0.75 approximately 3.00 mg/kg of sodium selenite could inhibit DNA damage of lung cells in mice induced by 250 mg/kg of BaP.