Nucleases play important roles in DNA synthesis, recombination and repair. We have previously shown that human exonuclease 1 (hEXO1) is phosphorylated in response to agents stalling DNA replication and that hEXO1 consequently undergoes ubiquitination and degradation in a proteasome-dependent manner. In the present study, we have addressed the identity of the pathway transducing stalled-replication signals to hEXO1. Using chemical inhibitors, RNA interference, ATM- and ATR-deficient cell lines we have concluded that hEXO1 phosphorylation is ATR-dependent. By means of mass spectrometry, we have identified the sites of phosphorylation in hEXO1 in undamaged cells and in cells treated with hydroxyurea (HU). hEXO1 is phosphorylated at nine basal sites and three additional sites are induced by HU treatment. Analysis of single- and multiple-point mutants revealed that mutation to Ala of the three HU-induced sites of phosphorylation partially rescued HU-dependent degradation of hEXO1 and additionally stabilized the protein in non-treated cells. We have raised an antibody to pS714, an HU-induced site of the S/T-Q type, and we provide evidence that S714 is phosphorylated upon HU but not IR treatment. The antibody may be a useful tool to monitor signal transduction events triggered by stalled DNA replication.

Cinnamon is used to flavor most foods in Arabian countries. The aim of this study was to evaluate the medicinal importance, reflecting an important trend in research. The hepatoprotective activity of aqueous and ethanolic extracts of cinnamon was investigated against carbon tetrachloride (CCl 4 ) induced lipid peroxidation and hepatic injury in rats. The elevated serum AST and ALT enzymatic activities induced by CCl 4 were significantly restored to near normal by oral administration of 200 mg/kg of either extracts once daily for 7 days, as compared to untreated rats. There was a significant elevation in the level of liver malondialdhyde (MDA), while the activities of antioxidant enzymes superoxide dismutase and catalase (SOD and CAT) were significantly decreased in CCl 4 intoxicated rats. The results obtained indicated that ethanolic extract has more potent hepatoprotective action than water extract against CCl 4 by lowering the MDA level and elevating antioxidants enzymes activities (SOD and CAT). The possible mechanism of this activity may be free radical-scavenging polyphenol compounds. The hepatoprotective properties were documented by the histopathological data obtained. Consequently, this extract can be used as a therapeutic regime in treatment of some hepatic disorders without any side effects. Further study will be done for separation and identification of active components and for testing antitumor activity.

Breast cancer is the principle cause of death among women worldwide. In this study, we investigated the anti-tumor potential of lycopene (Lyco) alone or combined with melatonin (Lyco + Mel) for 120 days against a single oral dose of (50 mg/kg B.W.) 7,12-dimethylbenz(a)anthracene (DMBA)-induced oxidative stress and mammary carcinogenesis in female rats. The treatment protocol started from the day immediately after DMBA administration. Results obtained indicated that there was an elevation in the levels of malondialdhyde and nitric oxide in serum and breast tissues of DMBA injected rats. The combined treatment (Lyco + Mel) group showed a potential reduction of these parameters more than lyco individually. The activities of SOD, CAT, and GPx were found to be significantly high than lyco alone treated rats. In DMBA group a negative significant correlation between weight and serum nitric oxide (r = -0.59), and a positive significant correlation between NO and MDA (r = 0.81) was observed. Histopathological examination revealed the formation of tumor and angiogenesis in DMBA-induced rats and these abnormal changes were ameliorated by combined treatment with Lyco + Mel. In conclusion, these results suggested that supplementation of diet with lycopene with melatonin provided antioxidant defense with strong chemo preventive activity against DMBA-induced mammary tumors.

Studying the pharmacokinetics of antiretroviral drugs in breast milk has important implications for the health of both the mother and the infant, particularly in resource-poor countries. Breast milk is a highly complex biological matrix, yet it is necessary to develop and validate methods in this matrix, which simultaneously measure multiple analytes, as women may be taking any number of drug combinations to combat human immunodeficiency virus infection. Here, we report a novel extraction method coupled to high-performance liquid chromatography and tandem mass spectrometry for the accurate, precise, and specific measurement of 7 antiretroviral drugs currently prescribed to infected mothers. Using 200 µL of human breast milk, simultaneous quantification of lamivudine (3TC), stavudine (d4T), zidovudine (ZDV), nevirapine (NVP), nelfinavir (NFV), ritonavir, and lopinavir was validated over the range of 10-10,000 ng/mL. Intraday accuracy and precision for all analytes were 99.3% and 5.0 %, respectively. Interday accuracy and precision were 99.4 % and 7.8%, respectively. Cross-assay validation with UV detection was performed using clinical breast milk samples, and the results of the 2 assays were in good agreement (P = 0.0001, r = 0.97). Breast milk to plasma concentration ratios for the different antiretroviral drugs were determined as follows: 3TC = 2.96, d4T = 1.73, ZDV = 1.17, NVP = 0.82, and NFV = 0.21.