Evaluation of the liver and blood micronucleus, and comet assay end points in a 14-day repeated-dose study with methyl carbamate and 1,3-propane sultone.

The repeated-dose liver micronucleus (RDLMN) assay is a novel method for detecting genotoxic chemicals. Two carcinogens methyl carbamate (MC) and 1,3-propane sultone (PS) were evaluated for the liver micronucleus in a 14-day repeated-dose study with Crl: CD (SD) IGS rats. Additionally, micronucleated reticulocytes (MN-RET) in peripheral blood and DNA damage (alkaline comet assay) in the liver were also assessed in the same animals. Ten groups of five male Crl: CD (SD) IGS rats were treated once daily with MC (300, 600 or 1200 mg/kg/day), PS (37.5, 75 or 150 mg/kg/day), negative control or three positive controls by oral gavage for 15 days. Blood samples were collected at 3 h after the last administration for determining MN-RET frequencies (%MN-RET), and the livers were sampled for determining the frequency of micronuclei and DNA damage. MC was negative in the comet assay, liver micronucleus assay and reticulocyte micronucleus assay, while PS was positive in all three assays. These results are consistent with the previous genotoxic findings of MC and PS. Therefore, the liver micronucleus assay can be effectively integrated into repeated-dose studies in animals. Moreover, integration of multiple genotoxicity end points into one study can reduce the number of animals, boost the experimental efficiency, and provides a comprehensive evaluation of the genotoxic potential of chemicals.

Acral purpura as leading clinical manifestation of dermatitis herpetiformis: report of two adult cases with a review of the literature.

Dermatitis herpetiformis (DH) is an autoimmune disease that clinically manifests as pruritic vesicles and papules. The diagnosis of DH is often challenging because of its wide spectrum of clinical presentations. We here report 2 patients with DH in whom finger petechiae represented the initial and leading manifestation of the disease, and the confirmed diagnosis critically relied on immunopathological studies. Therefore, besides the classic causes, clinicians should also consider DH in the differential diagnosis of acral purpura, even in patients only presenting with discrete acral petechial lesions. We also review the recent literature regarding the rare cases of petechiae in adult DH patients.

Genotoxicity of quinocetone, cyadox and olaquindox in vitro and in vivo.

Quinocetone (QCT) and Cyadox (CYA) are important derivative of heterocyclic N-oxide quinoxaline (QdNO), used actively as antimicrobial feed additives in China. Here, we tested and compared the genotoxic potential of QCT and CYA with olaquindox (OLA) in Ames test, HGPRT gene mutation (HGM) test in V79 cells, unscheduled DNA synthesis (UDS) assay in human peripheral lymphocytes, chromosome aberration (CA) test, and micronucleus (MN) test in mice bone marrow. OLA was found genotoxic in all 5 assays. In Ames test, QCT produced His(+) mutants at 6.9 µg/plate in Salmonella typhimurium TA 97, at 18.2 µg/plate in TA 100, TA 1535, TA 1537, and at 50 µg/plate in TA 98. CYA produced His(+) mutants at 18.2 µg/plate in TA 97, TA 1535, and at 50 µg/plate in TA 98, TA 100 and TA 1537. QCT was found positive in HGM and UDS assay at concentrations ≥10 µg/ml while negative results were reported in CA test and MN test. Collectively, we found that OLA was more genotoxic than QCT and CYA. Genotoxicity of QCT was found at higher concentration levels in Ames test, HGM and UDS assays while CYA showed weak mutagenic potential to bacterial cells in Ames test.

Genotoxicity evaluation of stearic acid grafted chitosan oligosaccharide nanomicelles.

Stearic acid grafted chitosan oligosaccharide (CSO-SA) nanomicelles could be promptly internalized into cancer cells; therefore, it is regarded as a promising drug carrier for cancer therapy. However, the toxicity of CSO-SA is not clear. In the present study, the genotoxic effects of CSO-SA nanomicelles (with high substitution degree of SA, 42.6±3.8%) were evaluated with a battery of genotoxicity assays. Mutagenicity was not found in Ames Salmonella/microsome mutagenicity assay (Ames test), while mild but definite positive results were observed in mouse bone marrow micronucleus assay and single cell gel electrophoresis (SCGE or comet assay) in A549 cells. CSO-SA was also found to induce apoptosis and oxidative stress through the induction of reactive oxygen species (ROS) in a dose-dependent manner in A549 cells. Preincubation with the free radical scavenger N-acetyl-l-cysteine (NAC) decreased the intracellular ROS level and alleviated the DNA damage in A549 cells. Expression levels of cleaved poly ADP-ribose polymerase (PARP), caspase-9 and caspase-3, markers of apoptosis, were significantly higher in CSO-SA treated cells. In conclusion, these results suggested significant genotoxicity of high doses of CSO-SA nanomicelles in vivo and in vitro. Oxidative stress was, at least partially, the possible mechanism underlying the genotoxicity induced by CSO-SA.