Genotoxicity testing of arsenobetaine, the predominant form of arsenic in marine fishery products

Marine fishery products may contain high levels of arsenic, mainly in the form of organic arsenic compounds. Arsenobetaine has been identified as the predominant form occurring in marine fishery products. The potential initiating and promoting capacities of this compound were therefore investigated in vitro. In the Salmonella typhimurium assay, no mutagenicity was observed in strains TA97, TA98 and TA100 without activation or after addition of a liver-enzyme fraction or gut-flora extract. The compound was also negative in the forward mutation assay of the HGPRT gene and in the test for sister chromatid exchanges in V79 Chinese hamster cells. No inhibition of metabolic co-operation between V79 Chinese hamster cells was observed at arsenobetaine concentrations up to 10 mg/ml. In addition, arsenobetaine had no synergistic or antagonistic effects on the action of the positive controls benzo[a]pyrene and tetradecanoylphorbol-13-acetate.     

The tumor promoter 12-O-tetradecanoylphorbol 13-acetate (TPA) provokes a prolonged morphologic response and ERK activation in Tsc2-null renal tumor cells.

Loss of tumor suppressor function dramatically alters the cellular response to chemicals. The phorbol ester tumor promoter, 12-O-tetradecanoylphorbol 13-acetate (TPA), stimulates cell proliferation through rapid activation of protein kinase C (PKC), followed by gradual degradation of the kinase. TPA also activates the GTPase Rap1 in some cell types. The tumor suppressor protein Tsc2 has a proposed GTPase activating protein (GAP) function for Rap1, providing a common mechanistic target for Tsc2 and TPA. We compared the cellular response of Tsc2-null (ERC-18) and Tsc2-competent (NRK-52E) renal epithelial cells to TPA treatment. Treatment of ERC-18 cells with 100 ng/ml TPA for 24 h resulted in loss of cell-cell contact, retraction of the cell periphery and rounding. These changes were reversed 1 h after treatment in NRK-52E cells and were apparent 24 h after treatment of ERC-18 cells. Expression of Tsc2 in ERC-18 cells abrogated the prolonged morphologic response. TPA treatment rapidly increased phosphorylation of ERK, a reported downstream effector of both PKC and Rap1, in ERC-18 cells, but induced weak Rap1 activation. TPA-induced ERK phosphorylation was prolonged in ERC-18 cells compared to NRK-52E cells and expression of Tsc2 in ERC-18 cells did not inhibit prolonged ERK activation. The selective PKC inhibitor, bisindolylmaleimide VIII, however, inhibited TPA-induced changes in morphology and ERK activation. These results imply that TPA-induced changes in morphology and ERK activation are mediated primarily through PKC and not Rap1 in renal epithelial cells. These data also imply that Tsc2 expression modulates TPA-induced changes in renal epithelial cell morphology via an ERK-independent mechanism.     

Correlation between EGFR Y1068 tyrosine phosphorylation and AP-1 activation by tumor promoter 12-O-tetradecanoylphorbol-13-acetate in mouse skin

The mouse skin carcinogenesis is unique model for our understating of molecular events leading to tumor development. The tumor promoter, 12-O-tetradecanoylphorbol-13-acetate (TPA) activates a variety of signaling pathways, including MAPK/AP-1. In this study, we examined the time course of EGFR phosphorylation and AP-1 activation in mouse epidermis after topical application of a single 10 nmol dose of TPA. Remarkable differences in the phosphorylation kinetics of EGFR tyrosine residues were observed. While the maximal level of Y1068 tyrosine phosphorylation occurred 4 h after TPA treatment, the Y1173 residue phosphorylation was initially down-regulated, and reached the highest level after 24 h. Phosphorylation of Y1068 tyrosine was correlated with AP-1 activation and c-Jun N-terminal kinase (JNK) activity. These results indicate that the stimulation of AP-1 in mouse epidermis by TPA may be the effect of EGFR activation, but not all tyrosine residues forming its catalytic center are equally involved in this process.     

白藜芦醇及其类似物的合成及抗TPA促癌作用研究

目的设计合成白藜芦醇类似物 ,并测试其抗佛波酯 (TPA)促癌作用。方法以 3,5 二羟基苯甲酸为原料经多步反应合成目标化合物 ,采用TPA致小鼠耳肿胀促癌法确定目标化合物抗TPA促癌作用。结果所有合成的目标化合物通过1H NMR确认其结构 ,大部分化合物具有明显的抗TPA促癌作用。结论白藜芦醇及其类似物具有较强抗TPA促癌作用。     

Protein kinase C isoforms as specific targets for modulation of vascular smooth muscle function in hypertension

Vascular contraction is an important determinant of the peripheral vascular resistance and blood pressure. The mechanisms underlying vascular smooth muscle (VSM) contraction and the pathological changes that occur in hypertension have been the subject of numerous studies and interpretations. Activation of VSM by vasoconstrictor stimuli at the cell surface causes an increase in [Ca(2+)](i), Ca(2+)-dependent activation of myosin light chain (MLC) kinase, MLC phosphorylation, actin-myosin interaction and VSM contraction. Additional signaling pathways involving Rho-kinase and protein kinase C (PKC) may increase the myofilament force sensitivity to [Ca(2+)](i) and MLC phosphorylation, and thereby maintain vascular contraction. PKC is a particularly intriguing protein kinase as it comprises a family of Ca(2+)-dependent and Ca(2+)-independent isoforms, which have different tissue and subcellular distribution, and undergo differential translocation during cell activation. PKC translocation to the cell surface may trigger a cascade of protein kinases, such as mitogen-activated protein kinase (MAPK) and MAPK kinase (MEK) that ultimately interact with the contractile myofilaments and cause VSM contraction. Also, PKC translocation to the nucleus may promote VSM growth and proliferation. Increased PKC expression and activity have been identified in several forms of hypertension. The subcellular location of PKC may determine the state of VSM activity, and may be useful in the diagnosis/prognosis of hypertension. Vascular PKC isoforms may represent specific targets for modulation of VSM hyperactivity, and isoform-specific PKC inhibitors may be useful in treatment of Ca(2+) antagonist-resistant forms of hypertension.     

对苯二甲酸吸入染尘大鼠BALF细胞与生化反应

分析动式吸入对苯二甲酸(TPA)粉尘大鼠支气管肺泡灌洗液(BALF)中细胞与生化反应,各实验组染尘几何平均浓度分别为8.93mg/m³、274.45mg/m³、618.12mg/m³.结果显示,中、高浓度组肺泡巨噬细胞(PAMs)计数比对照组显着减少,酸性磷酸酶(ACP)活性显着升高,高浓度组N-乙酰-β-D-氨基葡糖苷酶(NAG)活性显着高于对照组,提示TPA粉尘吸入对大鼠PAMs有损伤作用;BALF中蛋白质含量变化可能有免疫过程参与.     

Safety assessment of sandalwood oil (Santalum album L.).

Sandalwood (Santalum album L.) is a fragrant wood from which oil is derived for use in food and cosmetics. Sandalwood oil is used in the food industry as a flavor ingredient with a daily consumption of 0.0074 mg/kg. Over 100 constituents have been identified in sandalwood oil with the major constituent being alpha-santalol. Sandalwood oil and its major constituent have low acute oral and dermal toxicity in laboratory animals. Sandalwood oil was not mutagenic in spore Rec assay and was found to have anticarcinogenic, antiviral and bactericidal activity. Occasional cases of irritation or sensitization reactions to sandalwood oil in humans are reported in the literature. Although the available information on toxicity of sandalwood oil is limited, it has a long history of oral use without any reported adverse effects and is considered safe at present use levels.     

Suppression of the onset and progression of collagen-induced arthritis in rats by QFGJS, a preparation from an anti-arthritic Chinese herbal formula

QFGJS is an herbal preparation, and its pronounced effectiveness in treating adjuvant-induced arthritis (AIA) has been previously demonstrated. We herein aimed to confirm its anti-arthritic effect on collagen-induced arthritis (CIA) in rats. CIA was established in female Wistar rats with intradermal injection of type II bovine collagen at the base of the tail of animals. CIA rats were treated daily with oral administration of different doses of QFGJS beginning on the day of the induction of arthritis (day 0, the prophylactic treatment) or on the day after the onset of arthritis (day 13, the therapeutic treatment) until day 30. The results showed that prophylactic treatment with QFGJS significantly suppressed the onset of arthritis, and therapeutic treatment with QFGJS markedly reduced paw swelling and ESR levels even in the established CIA. Radiologic and histopathologic changes in the arthritic joints were also significantly reduced in the QFGJS-treated versus vehicle-treated rats. Moreover, the serum levels of pro-inflammatory cytokines TNF-alpha, IL-1beta, and IL-6 were markedly lowered in the QFGJS-treated rats. Hence, our studies demonstrate the quality, safety, and effectiveness of QFGJS as an anti-arthritic agent, which makes QFGJS a strong candidate for further clinical trials on rheumatoid arthritis (RA) patients.     

Assessment of anti-inflammatory and antinociceptive activities of Daphne pontica L. (Thymelaeaceae)

The n-hexane, diethylether, ethyl acetate and methanol extracts from roots, leaves, stems and flowers with young leaves of Daphne pontica L. (Thymelaeaceae) were investigated for their in vivo anti-inflammatory and antinociceptive activities. For the anti-inflammatory activity assessment, carrageenan-induced hind paw edema, PGE(2)-induced hind paw edema and 12-O-tetradecanoyl-13-acetate (TPA)-induced mouse ear edema models and for the antinociceptive activity, p-benzoquinone-induced abdominal constriction test were used. Only ethyl acetate extracts of the roots showed significant anti-inflammatory activity on carrageenan-induced (22.7-32.0% inhibition) and PGE(2)-induced hind paw edema (3.2-27.3% inhibition) as well as 12-O-tetradecanoyl-13-acetate (TPA)-induced mouse ear edema (47.8-43.3% inhibition) models at 50 mg/kg dose without inducing any apparent gastric lesion or acute toxicity, whereas the other extracts were shown to be ineffective. In addition to roots, ethyl acetate extracts of the stems exhibited 19.5-29.9%; 5.3-23.9%; 36.6-28.1% inhibition on carrageenan-induced and PGE(2)-induced hind paw edema as well as 12-O-tetradecanoyl-13-acetate (TPA)-induced mouse ear edema models, respectively. On the other hand, none of the extracts showed any significant antinociceptive activity.