Databases applicable to quantitative hazard/risk assessment--towards a predictive systems toxicology

The Workshop on The Power of Aggregated Toxicity Data addressed the requirement for distributed databases to support quantitative hazard and risk assessment. The authors have conceived and constructed with federal support several databases that have been used in hazard identification and risk assessment. The first of these databases, the EPA Gene-Tox Database was developed for the EPA Office of Toxic Substances by the Oak Ridge National Laboratory, and is currently hosted by the National Library of Medicine. This public resource is based on the collaborative evaluation, by government, academia, and industry, of short-term tests for the detection of mutagens and presumptive carcinogens. The two-phased evaluation process resulted in more than 50 peer-reviewed publications on test system performance and a qualitative database on thousands of chemicals. Subsequently, the graphic and quantitative EPA/IARC Genetic Activity Profile (GAP) Database was developed in collaboration with the International Agency for Research on Cancer (IARC). A chemical database driven by consideration of the lowest effective dose, GAP has served IARC for many years in support of hazard classification of potential human carcinogens. The Toxicological Activity Profile (TAP) prototype database was patterned after GAP and utilized acute, subchronic, and chronic data from the Office of Air Quality Planning and Standards. TAP demonstrated the flexibility of the GAP format for air toxics, water pollutants and other environmental agents. The GAP format was also applied to developmental toxicants and was modified to represent quantitative results from the rodent carcinogen bioassay. More recently, the authors have constructed: 1) the NIEHS Genetic Alterations in Cancer (GAC) Database which quantifies specific mutations found in cancers induced by environmental agents, and 2) the NIEHS Chemical Effects in Biological Systems (CEBS) Knowledgebase that integrates genomic and other biological data including dose-response studies in toxicology and pathology. Each of the public databases has been discussed in prior publications. They will be briefly described in the present report from the perspective of aggregating datasets to augment the data and information contained within them.     

注射用伏立康唑前药的遗传及生殖毒性研究

目的 研究注射用伏立康唑前药(Voriconazole prodrug,VP)的遗传及生殖毒性.方法 分别采用Ames试验、中国仓鼠肺细胞(CHL)染色体畸变试验、小鼠骨髓微核试验,观察VP的遗传毒性,并通过伴随毒动学试验了解其血浆暴露量;生殖毒性研究了注射用VP对SD大鼠胚胎-胎仔发育毒性的影响,于SD大鼠妊娠第6～ 15天连续iv给药(30、60、120 mg· kg-1·d-1),于妊娠第20天剖检,分析其生殖毒性.结果 遗传毒性的Ames试验、CHL试验和微核试验中,结果均显示为阴性;伴随毒动学试验表明:受试物在小鼠体内呈线性消除;胚胎-胎仔发育毒性试验中,受试物高剂量组中胎鼠头颅骨和/或胸骨异常的数量与溶媒对照组相比显著增加.结论 注射用VP未见明显遗传毒性;受试物在120 mg·kg-1剂量下对胎鼠骨骼发育有一定的毒性作用,未见其他生殖毒性.     

Zinc inhibits aflatoxin B1-induced cytotoxicity and genotoxicity in human hepatocytes (HepG2 cells)

Aflatoxin B1 (AFB1) has strong carcinogenicity. Consumption of AFB1-contaminated agricultural products and the occurrence of hepatocellular carcinoma have received widespread attention. The aim of this paper was to investigate whether zinc supplementation could inhibit AFB1-induced cytotoxicity and genotoxicity in HepG2 cells and the mechanism of this inhibition. Our data suggest that zinc sources can relieve a certain degree of AFB1-induced cytotoxicity and genotoxicity by protecting against apoptotic body formation and DNA strand breaks, affecting S phase cell cycle arrest, reducing 8-OHdG formation, inhibiting global DNA hypomethylation and regulating gene expression in antioxidation, zinc-association and apoptosis processes. Consequently, zinc stabilizes the integrity of DNA and improves cell survival.These data provides new insights into the protective role of zinc in alleviating AFB1-induced cytotoxicity and mediating epigenetic changes in hepatocytes, demonstrating that zinc sources have detoxification properties in mycotoxin-induced toxicity.     

Genotoxicity and subchronic toxicity evaluation of dried Euglena gracilis ATCC PTA-123017

Euglena gracilis is a microalga capable of synthesizing various nutrients of interest in human and animal nutrition. When cultivated aerobically in the dark, Euglena synthesize paramylon, a storage polysaccharide comprised of high molecular weight beta-1,3-D-glucose polymers organized in cytoplasmic granules. Beta-glucans have been shown to have immune modulation effects, including anti-microbial, anti-tumor, and anti-oxidant properties, and metabolic effects, such as regulation of cholesterol and blood sugar levels. Preparations of E. gracilis and paramylon may therefore have potential utility as functional food ingredients for human and animal nutrition. A battery of toxicological studies was conducted on a dried preparation of E. gracilis and paramylon to support their safe food use. The dried alga was not genotoxic in a bacterial reverse mutation test and mammalian micronucleus test. In the subchronic toxicity study, rats were provided E. gracilis in the diet at levels of 0, 12,500, 25,000 or 50,000 ppm. Paramylon was provided at a concentration of 50,000 ppm. No effects that could be attributable to treatment were observed in clinical observations, body weight, food consumption, ophthalmology, hematology and clinical chemistry, urinalysis, and macroscopic and microscopic findings. A NOAEL of 50,000 ppm in the diet was determined for both ingredients.     

Radiobiological risks following dentomaxillofacial imaging: should we be concerned?

Objectives:This review aimed to present studies that prospectively investigated biological effects in patients following diagnostic dentomaxillofacial radiology (DMFR).Methods:Literature was systematically searched to retrieve all studies assessing radiobiological effects of using X-ray imaging in the dentomaxillofacial area, with reference to radiobiological outcomes for other imaging modalities and fields.Results:There is a lot of variability in the reported radiobiological assessment methods and radiation dose measures, making comparisons of radiobiological studies challenging. Most radiological DMFR studies are focusing on genotoxicity and cytotoxicity, data for 2D dentomaxillofacial radiographs, albeit with some methodological weakness biasing the results. For CBCT, available evidence is limited and few studies include comparative data on both adults and children.ConclusionsIn the future, one will have to strive towards patient-specific measures by considering age, gender and other individual radiation sensitivity-related factors. Ultimately, future radioprotection strategies should build further on the concept of personalized medicine, with patient-specific optimization of the imaging protocol, based on radiobiological variables.     

Nanotoxicology and in vitro studies: the need of the hour

Nanotechnology is considered as one of the key technologies of the 21st century and promises revolution in our world. Objects at nano scale, take on novel properties and functions that differ markedly from those seen in the corresponding bulk counterpart primarily because of their small size and large surface area. Studies have revealed that the same properties that make nanoparticles so unique could also be responsible for their potential toxicity. Nanotechnology is rapidly advancing, with more than 1000 nanoproducts already on the market. Considering the fact that intended as well as unintended exposure to nanomaterials is increasing and presently no clear regulatory guideline(s) on the testing/evaluation of nanoparticulate materials are available, the in vitro toxicological studies become extremely relevant and important. This review presents a summary of nanotoxicology and a concise account of the in vitro toxicity data on nanomaterials. For nanomaterials to move into the applications arena, it is important that nanotoxicology research uncovers and understands how these multiple factors influence their toxicity so that the ensuing undesirable effects can be avoided.     

Assessment of DNA damage in postmenopausal women under osteoporosis therapy

OBJECTIVE: The following study was designed to examine possible DNA damage levels in peripheral blood leukocytes, using the alkaline Comet assay, isolated from postmenopausal women undergoing osteoporosis treatment. STUDY DESIGN: Thirty-two postmenopausal women were randomized into two groups of 16. A dosage of 2.5 mg/day of tibolone (Livial) and 10mg/day of alendronate sodium (Fosamax) were administered to Group 1 over a 12-month period while Group 2 took 10 mg/day of alendronate alone over the same period. The control group consisted of 16 postmenopausal women who did not receive any treatment. Genotoxicity was assessed by the standard method of alkaline Comet assay. RESULTS: When the results of the study groups were compared with those of the control group, significant differences in terms of DNA damage levels were found (p<0.05). However, no difference was detected between Groups 1 and 2 (p>0.05). CONCLUSION: Although, no statistical difference in terms of DNA damage levels between tibolone plus alendronate as opposed to alendronate alone was found, an increase in DNA damage levels was observed in Groups 1 and 2 compared with the control group. Consequently, it can be asserted that the frequency of DNA damage in postmenopausal women with osteoporosis increases under alendronate treatment with or without tibolone.     

Genotoxic and mutagenic properties of Bauhinia platypetala extract,a traditional Brazilian medicinal plant

Ethnopharmacological relevance

Bauhinia platypetala Burch. is a traditionally used Brazilian medicinal plant, although no evidence in the literature substantiates the safety of its use.

Aim of the study

The aim of this study was to investigate the safety of the ethanolic extract and the ethereal fraction of B. platypetala leaves.

Materials and methods

The identification of chemical compounds from the B. platypetala ethanolic extract and its ethereal fraction was performed by GC/MS and ESI-MS/MS. The plant’s toxicological, cytotoxic, mutagenic and genotoxic properties were determined in Saccharomyces cerevisiae strains and V79 cell culture by survival assays and comet assay.

Results

The major compound identified in the B. platypetala ethanolic extract is palmitic acid, kaempferitirin and quercitrin, while the B. platypetala ethereal fraction was found to be rich in phytol, gamma-sitosterol and vitamin E. Moreover, the results indicated that the B. platypetala ethanolic extract has an anti-oxidative effect against H₂O₂ in yeast. In addition, the B. platypetala ethanolic extract did not induce mutagenic effects on the S. cerevisiae N123 strain, but the ethereal fraction of B. platypetala at higher concentrations (250–500 μg/mL) induced cytotoxicity and mutagenicity. A slight cytotoxic effect was observed in mammalian V79 cells; however, both the B. platypetala ethanolic extract and its ethereal fraction were able to induce DNA strand breaks in V79 cells, as detected by the alkaline comet assay.

Conclusion

The B. platypetala ethanolic extract has antioxidant action and showed absence of mutagenic effects in yeast S. cerevisiae. On the other hand B. platypetala ethereal fraction is mutagenic and does not show antioxidant activity in yeast. In mammalian cells B. platypetala ethanolic extract and it's ethereal fraction induce cyotoxic and genotoxic action.     

多环芳烃遗传毒性研究进展

多环芳烃类化合物是广泛存在于各种环境介质中的一类有机污染物,并能通过呼吸、饮食、饮水、皮肤接触等多种途径进入人体,对人体健康和环境产生严重危害。关于多环芳烃的毒性研究已经涉及遗传毒性、肝脏毒性、生长发育毒性及致癌性等方面,该文综述了其遗传毒性的研究进展,主要包括DNA损伤、染色体损伤以及遗传易感性等。