Evaluation of cell and DNA damage induced by panoramic radiography.

BACKGROUND: X-rays are potential mutagenic agents that can cause both the gene mutations and chromosomal aberrations. AIMS: In this study, the micronucleus (MN) test and the comet assay methods are implemented in order to observe the damage that can occur in the cell nucleus and in the structure of DNA of the patients who underwent a panoramic examination. METHODS AND MATERIALS: In our study, buccal mucosa swabs were obtained just before the radiography and 2 weeks after the radiography from 30 volunteer patients who had to take radiographs due to dental diagnosis. Changes in the nuclei of 1,000 cells of each swab sample had been counted under a light microscope and recorded. Besides, 100 cells of each other swab samples were analyzed by the comet assay. Comet assay parameters namely tail length and percentage of DNA in tail, which indicate the level of DNA damage were analyzed and compared in both groups. Statistical analysis was performed by using the Statistical Package for the Social Sciences (Version 21). RESULTS: In our study, the results of percentage of DNA in tail and tail length before and after X-ray exposure were statistically significant (P < 0.001). Likewise, increase in the MN frequency observed in buccal mucosa cells after X-ray exposure was found significant (P < 0.001). CONCLUSIONS: As a result, panoramic radiographs taken during dental diagnosis and treatment cause cytotoxicity and DNA damage in oral mucosal cells. Panoramic radiographs should be applied only when necessary, using an accurate radiographic technique and radioprotection criteria.

Induction of apoptosis by Centaurea nerimaniae extract in HeLa and MDA-MB-231 cells by a caspase-3 pathway.

We investigated the cytotoxic and apoptotic effects of a methanol extract of Centaurea nerimaniae, a plant endemic in Turkey, on HeLa and MDA-MB-231 cells. Eight concentrations of C. nerimaniae extract were applied to cells, and cytotoxic effects were measured using the xCELLigence system. The TUNEL assay was used to assess apoptotic cell death and immunohistochemistry was used to determine active caspase-3 using the effective cytotoxic doses of the extract. Doses of 1.42 mg/ml C. nerimaniae inhibited the growth of HeLa cells and 3.67 mg/ml C. nerimaniae inhibited the growth of MDA-MB-231 cells in a dose- and time-dependent manner. The apoptotic indexes for HeLa and MDA-MB-231 cells were increased significantly compared to control groups. Immunohistochemistry showed that the number of caspase-3 immunostained cells increased in the extract treatment groups for both HeLa and MDA-MB-231 cells. In the MDA-MB-231 cell line, caspase-3 immunostaining was observed in nuclei and/or cytoplasm in the extract treated group. Caspase-3 activation was greater in HeLa cells than in MDA-MB-231 cells. We found that the extract of C. nerimaniae had a strong antiproliferative effect and induced apoptosis via caspase-3; MDA-MB-231 cancer cells were more resistant than HeLa cells.

Comparison of the metabolic and antioxidant effects of diltiazem and vitamin E on streptozotocin-diabetic rats.

In this study, solitary and combined effects of vitamin E and the calcium-channel blocker diltiazem were investigated in streptozotocin (STZ)-induced diabetic rats. Thirty male Wistar albino rats, weighing approximately 200 g were used. Diabetes mellitus was induced by a single intravenous injection of STZ at a dose of 65 mg/kg body weight. Five experimental groups were established as STZ-diabetic, STZ-diabetic + vitamin E, STZ-diabetic + diltiazem and STZ-diabetic + vitamin E + diltiazem. Vitamin E was injected intraperitoneally three times a week at a dose of 500 mg/kg body weight. Diltiazem was given orally every day at a dose of 25 mg/kg body weight. At the end of the study (10 weeks) blood glucose levels of diabetic rats, which had received vitamin E and diltiazem, had significantly decreased when compared with untreated diabetic rats (P < 0.02). Similarly, HbA1c levels had significantly decreased in diabetic rats which had received vitamin E (P < 0.05), diltiazem (P < 0.01) and vitamin E + diltiazem (P < 0.02) when compared with untreated diabetic rats. Liver glutathione levels of diabetic rats, which had received vitamin E (P < 0.01) and vitamin E + diltiazem (P < 0.05) had significantly increased when compared with untreated diabetic rats. Liver lipid peroxide levels had significantly decreased in diabetic rats, which had received vitamin E (P < 0.001) and diltiazem (P < 0.01). With respect to their metabolic and antioxidant effects, vitamin E proved superior to diltiazem.

On the mode of inhibition of eukaryotic protein synthesis by ADP-ribosylation of elongation factor 2.

The exchange of free guanine nucleotides with guanine nucleotides bound to elongation factor 2 (EF-2) and to the EF-2-ribosome complex, and the effect of ADP-ribosylation of the EF-2 thereon, were investigated by nitrocellulose filter assay. Under the experimental conditions, stoichiometric amounts of guanine nucleotides were bound, in particular, to ternary complexes of EF-2 with biphasic kinetics. The exchange kinetics were similarly biphasic in all cases. Ribosomes appeared to have variable effects on the exchange kinetics, depending on the type of nucleotide bound. Thus, in their presence, the rate and magnitude of the fast exchange of nucleotides revealed increasing values in the order GTP (GXP) > GTP gamma S > GDP. ADP-ribosylation had no inhibitory effect on the binding of guanine nucleotides to EF-2 or to the EF-2-ribosome complex but reduced significantly the fast exchange of GTP (GXP) and GTP gamma S bound to the EF-2-ribosome complex. The effect of ADP-ribosylation on the fast exchange of GDP in binary and ternary complexes was less pronounced. The mechanism of inhibition of protein synthesis by ADP-ribosylation of EF-2 is discussed in view of these data.

ADP-ribosylation of serum proteins: elevated levels in neoplastic cases due to altered NAD/ADP-ribose metabolism.

ADP-ribosylation of human serum proteins was studied in various groups of disorders. In most of these groups, the extent of ADP-ribosylation did not show a divergence from the group of normal controls. Neoplastic diseases revealed, however, a unique group, with more than fivefold increases in ADP-ribosylation levels over the other groups. Blood samples with high levels of ADP-ribosylation revealed, in general, increased serum NAD glycohydrolase activities and low levels of serum NAD.

ADP-ribosylation of serum proteins: evaluation as a potential tumor marker.

Serum samples from cancer patients revealed elevated levels of in vitro ADP-ribosylation through non-enzymic binding of ADP-ribose to free acceptor sites on serum proteins. Low concentrations of serum ADP-ribose caused by high NAD glycohydrolase activity together with elevated rates of ADP-ribose transport into erythrocytes appeared to account for under-saturation of the acceptor sites on serum proteins. ADP-ribosylation of serum proteins was assessed as an indicator of cancer disease, and an attempt was made to determine the correlation of ADP-ribosylation levels with carcinoembryonic antigen (CEA) values. Based on positive test results for all tumor patients and negative test results for all healthy controls, sensitivity and specificity of ADP-ribosylation as a tumor indicator were estimated as 67% and 95%, respectively. A close correlation appeared to exist with CEA (r = 0.67; P < 0.001). Similarly, the changes in the levels of ADP-ribosylation correlated with the changes in the levels of CEA during the clinical course (r = 0.58; P < 0.05).