Buccal micronucleus cytome assay of populations under chronic heavy metal and other metal exposure along the Santiago River, Mexico.

The Santiago River is one of the most contaminated rivers in Mexico, with heavy metal levels above the allowed limits. Scientific evidence indicates that chronic heavy metal exposure leads to cytogenotoxic effects. The aims of this study were to evaluate the genotoxic and cytotoxic effects of such exposure in buccal mucosa cells by micronucleus (MN) assay and to identify other nuclear abnormalities (NAs), such as nuclear buds (NBUDs), binucleated cells (BNs), pyknotic nuclei (PNs), karyorrhexis (KX), karyolysis (KL), and abnormally condensed chromatin (CC). Assays were performed on samples from four populations located alongside the Santiago River that are under chronic exposure to heavy metals and other metals (HMMs), and the results were compared with those of a population without exposure to HMMs. The exposed group showed increased frequencies of NAs (KX, CC, and KL), which are associated with cytotoxic damage, and NBUDs, which are associated with genotoxic damage. Increased frequencies of NBUDs and CC were observed in subjects from El Salto/Juanacatlán, Ocotlán, and Paso de Guadalupe, and an increase in KX frequency was observed in subjects from El Salto/Juanacatlán. Significant differences in KL frequency were observed in subjects from La Barca, El Salto/Juanacatlán, Paso de Guadalupe, and Ocotlán. Predictors for increased development of MNs and NBUDs were high concentrations of Al, Zn, and Cu. In conclusion, chronic exposure to HMMs, especially Al, Cu, and Zn, in the studied population could be related to increased frequencies of NAs, such as NBUDs, KX, CC, and KL, in the buccal mucosa cells.

Pirfenidone prevents rat esophageal stricture formation.

BACKGROUND: Accidental ingestion of caustic substances induces esophageal injuries and stenosis formation. The main aim for acute phase treatment is to prevent esophageal stenosis. Pirfenidone (PFD) is a pyridone with antifibrotic and anti-inflammatory effects. Esophagus stenosis takes place after a strong inflammation process where proinflammatory and profibrogenic cytokines play an important role. The present study investigates the efficacy of PFD on the prevention of stricture development after esophageal caustic injuries in a rat model. MATERIAL AND METHODS: Caustic esophageal burn was produced by application of 32% of NaOH to the distal esophagus of healthy rats. PFD in the form of 8% gel was administered at a dose of 200 mg/kg/d. Animals were divided in three experimental groups as follows: healthy rats, animals injured with NaOH without PFD treatment, and rats injured with NaOH and treated with PFD. Efficacy of the treatment was assessed by measuring image esophagoscopy and esophagography with contrast barium at the 21st d. Histology staining with Sirius-red was performed to evaluate collagen deposition and stenosis area. Gene expression of transforming growth factor ß1, collagen-1, plasminogen activator inhibitor-1, connective tissue growth factor, and matrix metalloproteinase 2 were measured by quantitative reverse transcription polymerase chain reaction. RESULTS: There was significant difference in means of stenosis by esophagoscopy and esophagogram. Collagen deposition in the damaged area increased significantly when rats were burned with NaOH, and decreased notably in PFD treated group. Profibrogenic key molecules transforming growth factor ß1, collagen 1, plasminogen activator inhibitor-1 and connective tissue growth factor expression were significantly lower respect to control group without PFD treatment where matrix metalloproteinase 2 expression was no different in all groups. CONCLUSIONS: This study suggests that PFD reduces stenosis on caustic esophageal burn by decreasing profibrogenic genes expression and ameliorates fibrosis significantly in the chronic phase.