Ana Carolina Cuzzuol Fracalossi

Cardioprotective actions of ascorbic acid during isoproterenol-induced acute myocardial infarction in rats.

Background/Aims: In the present study, we tested whether or not acute antioxidant treatment with vitamin C is able to protect the heart during myocardial infarction. The effects of vitamin C on the autonomic balancing of the heart and on the histopathological and immunohistochemical changes in response to isoproterenol administration (ISO) were evaluated. Methods: Four groups of male Wistar rats (n = 32) were studied: control; ISO treated; vitamin C treated; ISO + vitamin C treated. ISO 150 mg/kg was administered for 2 consecutive days. Vitamin C (250 mg/kg, oral) was administered 30 min before each ISO treatment. Phenylephrine and sodium nitroprusside were administrated to increase or decrease blood pressure in conscious rats. Results: The baroreceptor reflex index for bradycardia was significantly reduced in the ISO group (control, –3.4 ± 0.3 beats/mm Hg; ISO –2 ± 0.4 beats/mm Hg) and vitamin C treatment significantly improved the reflex index (–2.9 ± 0.7 beats/mm Hg). Treatment with vitamin C showed mild degenerative changes in the myocardial tissue of the ISO group. The antioxidant was able to decrease the inducible nitric oxide (iNOS) expression in rats treated with vitamin C. Conclusion: Vitamin C administration proved to be effective in reducing the extent of myocardial damage during ISO-induced myocardial infarction in rats associated with an iNOS downregulation and improving the autonomic balancing of the heart.

Wnt/β-catenin signalling pathway following rat tongue carcinogenesis induced by 4-nitroquinoline 1-oxide

The Wnt/beta-catenin signaling pathway plays an important role in development, tissue homeostasis, and regeneration. Inappropriate activation of the Wnt pathway is linked to a wide range of human cancers. The purpose of this study was to characterize the Wnt/beta-catenin signaling pathway as depicted by the expression of Wnt1, Frizzled-1, Wnt5a, Frizzled-5 and beta-catenin during 4NQO-induced rat tongue carcinogenesis by immunohistochemistry. Male Wistar rats were distributed into three groups of 10 animals each and treated with 4NQO solution at 50 ppm through their drinking water for 4, 12, and 20 weeks. Ten animals were used as control group. No histopathological abnormalities were induced in the epithelium after 4 weeks of carcinogen exposure; however, an overexpression of Wnt5a was noticed when compared to control group (p<0.05). The Wnt1 showed significant differences (p<0.05) in pre-neoplastic lesions at 12 weeks following carcinogen exposure. In well-differentiated squamous cell carcinoma induced after 20 weeks of treatment with 4NQO, Wnt1 was expressed in the majority of the dysplasic cells and tumor cells. This was statistically significant (p<0.05). No significant differences (p>0.05) were found in expression of Frizzled-1, Frizzled-5 or beta-catenin following oral carcinogenesis. Taken together, our results support the belief that expression of Wnt1 and Wnt5a is related to malignant transformation and conversion of oral mucosa.

Radiopacifiers do not induce genetic damage in murine fibroblasts: an in vitro study.

AIM To evaluate whether several radiopacifiers are able to induce genetic damage in a laboratory cell culture study. METHODOLOGY Murine fibroblasts were exposed to barium sulphate, bismuth oxide or zirconium oxide, at final concentrations ranging from 10 to 1000 microg mL(-1) for 1 h at 37 degrees C. The negative control group was treated with a vehicle control [phosphate buffered solution (PBS)] for 1 h at 37 degrees C and the positive control group was treated with hydrogen peroxide (at 10 microM) for 5 min on ice. Genotoxicity data were assessed by the single-cell gel (comet) assay. RESULTS All the tested compounds did not induce DNA breakage as depicted by the mean tail moment in all the concentrations analysed. CONCLUSION Exposure to the tested radiopacifiers may not be a factor that increases the level of DNA lesions in mammalian cells as detected by a single-cell gel (comet) assay.

Mutagenicity and cytotoxicity in patients submitted to ionizing radiation.

OBJECTIVES To evaluate and compare mutagenicity (micronucleus) and cytotoxicity (karyorrhexis, pyknosis, and karyolysis) in exfoliated buccal mucosa cells of children following cone beam computed tomography (CBCT) or conventional radiograph exposure necessary for orthodontic planning. MATERIALS AND METHODS A total of 49 healthy children were submitted to CBCT or a conventional orthodontic radiographic protocol; they were divided into two groups based on exam: CBCT (n  =  24) and Radiographic Set (n  =  25) groups. The micronucleus test in the exfoliated buccal mucosa cells was applied. RESULTS There was not a statistically significant difference (P > .05) found between the number of micronucleated buccal mucosa cells (MNC) before and after exposure to radiation in either group, showing that neither group experienced a mutagenic effect. However, radiation did cause other nuclear alterations closely related to cytotoxicity, including karyorrhexis, pyknosis, and karyolysis, in both groups (P < .05). The CBCT group presented a greater increase in cell death than was noted in the Radiographic Set group (P < .044). CONCLUSION According to the micronucleus test, mutagenicity was not induced by the CBCT or the conventional radiographs, but cytotoxicity was verified after these exams, especially after CBCT. That might have happened once the CBCT group received a greater radiation dose than the Radiographic Set group as a result of the protocols used in orthodontic planning for this study.

Cytogenetic biomonitoring in children submitting to a complete set of radiographs for orthodontic planning.

OBJECTIVES To evaluate the DNA damage (micronucleus) and cellular death (pyknosis, karyolysis, and karyorrhexis) in exfoliated buccal mucosa cells from children undergoing orthodontic radiographs. MATERIALS AND METHODS A total of 25 healthy children undergoing orthodontic therapy partook in a complete set of orthodontic radiographs (lateral cephalographic, posteroanterior cephalographic, panoramic, full periapical exam, and bitewing). The micronucleus test in the buccal exfoliated cells was applied. The paired-samples t-test and the Wilcoxon test were used to compare the frequencies of alterations before and after X-ray exposure. RESULTS We found no statistically significant differences (P > .05) between micronucleated buccal mucosa cells before and after exposure to radiation. However, radiation did cause other nuclear alterations closely related to cytotoxicity (P  =  .007). CONCLUSION According to the micronucleus test, the complete set of radiographs requested in the orthodontic planning may not be a factor that induces chromosomal damage, but it is able to promote cytotoxicity.

The influence of sleep deprivation and obesity on DNA damage in female Zucker rats

OBJECTIVE: The aim of this study was to evaluate overall genetic damage induced by total sleep deprivation in obese, female Zucker rats of differing ages. METHOD: Lean and obese Zucker rats at 3, 6, and 15 months old were randomly distributed into two groups for each age group: home-cage control and sleep-deprived (N = 5/group). The sleep-deprived groups were deprived sleep by gentle handling for 6 hours, whereas the home-cage control group was allowed to remain undisturbed in their home-cage. At the end of the sleep deprivation period, or after an equivalent amount of time for the home-cage control groups, the rats were brought to an adjacent room and decapitated. The blood, brain, and liver tissue were collected and stored individually to evaluate DNA damage. RESULTS: Significant genetic damage was observed only in 15-month-old rats. Genetic damage was present in the liver cells from sleep-deprived obese rats compared with lean rats in the same condition. Sleep deprivation was associated with genetic damage in brain cells regardless of obesity status. DNA damage was observed in the peripheral blood cells regardless of sleep condition or obesity status. CONCLUSION: Taken together, these results suggest that obesity was associated with genetic damage in liver cells, whereas sleep deprivation was associated with DNA damage in brain cells. These results also indicate that there is no synergistic effect of these noxious conditions on the overall level of genetic damage. In addition, the level of DNA damage was significantly higher in 15-month-old rats compared to younger rats.

Movimentação dentária experimental em murinos: período de observação e plano dos cortes microscópicos

AIM: This study aims to elucidate the relevant microscopic aspects of induced tooth movement in murines with regard to: (1) different study periods; and (2) transverse and longitudinal directions of microscopic sections. Experimental studies on induced tooth movement in murines use variable study periods and directions of microscopic sections, including those studies that specifically use the model adopted by Heller and Nanda in 1979. This manuscript was prepared in order to contribute to: (1) selection of the best study design for future studies on induced tooth movement in murines, and (2) improve the analysis criteria to be used by other investigators. METHODS: The study was conducted on 50 male Wistar rats with 90 days of age, submitted to induced tooth movement for periods of 3, 5, 7 and 9 days. The maxillary left first molar was submitted to mesial inclination by application of 75cN of force. Qualitative microscopic analysis evaluated the tissue and cellular phenomena secondary to induced tooth movement, at the different study periods and on transverse and longitudinal sections. RESULTS: Among the phenomena investigated, hyaline areas of periodontal ligament were mostly observed at 5 days, and root resorptions were remarkable and well delineated at 9 days. Both phenomena affected mainly the distal roots, especially the distobuccal root. CONCLUSION: Considering the present objective, study periods of 5 to 9 days and transverse microscopic sections may be suggested for future studies on this subject.

Chromosome breakage and cellular death are induced in oral epithelial cells of hairdressers: a preliminary study

The aim of the present study was to comparatively evaluate genomic damage (micronucleus) and cellular death (pyknosis, karyolysis and karyorrhexis) in exfoliated oral mucosa cells from hairdressers using two different anatomic buccal sites: cheek mucosa and lateral border of the tongue. A total of 28 hairdressers and 30 health controls (non-exposed individuals) were included in this setting. Individuals had epithelial cells from the cheek and lateral border of the tongue mechanically exfoliated, placed in fixative and dropped in clean slides that were checked for the previously mentioned nuclear phenotypes. The results pointed out statistically significant differences (p < 0.05) of micronucleated oral mucosa cells from hairdressers in the lateral border of the tongue. Exposure to hair dyes caused an increase of other nuclear alterations closely related to cytotoxicity, such as karrhyorexis, pyknosis and karyolysis in both the oral sites evaluated. In summary, these data indicate that hairdressers are occupationally exposed to agents that are genotoxic and cytotoxic. It seems that the lateral border of the tongue is a more sensitive site to the genotoxic and cytotoxic effects of hair dyes.