Indoor radon exposure and excess of lung cancer mortality: the case of Mexico-an ecological study.

Radon is a radioactive gas that can migrate from soils and rocks and accumulate in indoor areas such as dwellings and buildings. Many studies have shown a strong association between the exposure to radon, and its decay products, and lung cancer (LC), particularly in miners. In Mexico, according to published surveys, there is evidence of radon exposure in large groups of the population, nevertheless, only few attention has been paid to its association as a risk factor for LC. The aim of this ecological study is to evaluate the excess risk of lung cancer mortality in Mexico due to indoor radon exposure. Mean radon levels per state of the Country were obtained from different publications and lung cancer mortality was obtained from the National Institute of Statistics, Geography and Informatics for the period 2001-2013. A model proposed by the International Commission on Radiological Protection to estimate the annual excess risk of LC mortality (per 105 inhabitants) per dose unit of radon was used. The average indoor radon concentrations found rank from 51 to 1863 Bq m-3, the higher average dose exposure found was 3.13 mSv year-1 in the north of the country (Chihuahua) and the mortality excess of LC cases found in the country was 10 ± 1.5 (range 1-235 deaths) per 105 inhabitants. The highest values were found mainly in the Northern part of the country, where numerous uranium deposits are found, followed by Mexico City, the most crowded and most air polluted area in the country. A positive correlation (r = 0.98 p < 0.0001) was found between the excess of LC cases and the dose of radon exposure. Although the excess risk of LC mortality associated with indoor radon found in this study was relatively low, further studies are needed in order to accurately establish its magnitude in the country.

Endocannabinoid receptor CB2 in nonalcoholic fatty liver disease.

BACKGROUND AND AIM: Fatty infiltration and fibrosis are major issues in chronic liver disease. Recent reports suggest a role for the endocannabinoid system in these processes. AIM: To characterize localization and expression of CB2 in normal liver and nonalcoholic fatty liver. METHODS: We studied 64 liver biopsies: eight were considered normal; 56 had a diagnosis of nonalcoholic fatty liver disease (NAFLD); 32 with nonalcoholic steatosis and 24 nonalcoholic steatohepatitis (NASH). CB2 immunolocalization was studied in 38 samples in paraffin blocks using immunohistochemistry, and a computerized semiquantitative analysis was carried out. CB2 mRNA expression was assessed through RT-PCR in 26 frozen liver samples and the ratio CB2/beta-actin was used to evaluate differences between groups. Statistical analysis was performed with central tendency measures and the Mann-Whitney U-test. We considered as significant differences those with a P-value <0.05. RESULTS: Neither parenchymal nor nonparenchymal cells in normal liver tissue react towards anti-CB2 antibodies. All the samples from patients with steatosis and nonalcoholic steatohepatitis showed hepatocellular immunoreactivity. Cholangiocytes were positive only in the NAFLD group. Normal liver tissue showed a normalized CB2/beta-actin ratio of 0.001+/-0.01, steatosis 6.52+/-17.3 (P=0.05 vs normal) and NASH 6.49+/-12.2 (P=0.06 vs normal and P=0.6 vs steatosis). CONCLUSION: CB2 receptors are expressed by hepatocytes in nonalcoholic fatty liver disease but not in normal liver.

Pathophysiology of cholesterol gallstone disease.

The purpose of the present paper is to review the current knowledge about cholesterol gallstone disease. It is generally accepted that the formation of cholesterol gallstone requires three major pathogenic defects, namely, supersaturation, nucleation and crystal growth as well as disorder of gallbladder motility. The supersaturation is necessary but not sufficient to explain stone formation. It has been suggested that nucleation is the key factor for gallstone formation. However, those three factors are necessary for the formation of cholesterol gallstones, and the presence of just one or two factors does not lead to stones. We also touch briefly on the results from studies performed in Mexico in this area.

Gallstone composition in Mexican patients.

Prevalence of gallstone disease in Mexico is similar to that found in some European countries. Patients from those industrialized Western countries primarily develop cholesterol gallstones; however, we do not have information related to the chemical composition of gallstones in the Mexican population. The aim of this study was to determine the physiochemical characteristics of gallstones from patients undergoing surgery for symptomatic cholelithiasis. We analyzed gallstone specimens from 59 patients (17 male and 42 female) from five Mexican states and Mexico City by X-ray diffraction. The chemical analysis revealed that 71.2% of the patients had stones of mixed composition. We concluded that the chemical composition of gallstones found in Mexican patients is similar to that found in patients from other Western countries.

Prevalence of gallstone disease in Mexico. A necropsy study.

The prevalence of gallstone disease in Mexico was investigated by studying a sample of 21,446 necropsies performed at the Department of Pathology of the General Hospital of Mexico City during a 35-year period (1953-1988). For each decade, 1000 necropsy cases were randomly selected. The crude prevalence of gallstone disease was 14.3%, 8.5% for males and 20.4% for females. The age groups ranged from 20 to more than 80 years old; the age-standardized prevalence for males was 5.6% and for females 16.2%. These rates are intermediate between those found in Chile and some African countries, comparable to some European studies, and less than those found in Mexican-Americans. No significant trend in the prevalence of gallstone disease was found when the different decades were compared.

Evaluacion del efecto del mycrodyn, elibac, nibac y trop-fen sobre huevos de cestodos / Evaluation of the effect of microdyn, elibac, nibac and trop-fen on the eggs of cestodes

Se trataron huevos de Taenia saginata, T.hydatigena y T. pisiformis, con diferentes diluciones de los productos quimicos microdyn, elibac, nibac y trop-fen durante 24 horas, con objeto de determinar su accion ovicida. Se observo el efecto que estos agentes tienen sobre los huevos antes de someterlos a la digestion artificial para evaluar los posibles danos morfologicos, que no se encontraron.La presencia de oncosferas libres con citoplasma y forma normales, ademas de movimientos de los ganchos del embrion despues de la incubacion de los huevos con jugos gastricos e intestinales, fueron los criterios utilizados para determinar su vitalidad. El microdyn, elibac, nibac y trop-Fen no tuvieron actividad ovicida sobre los huevos de estos cestodos, aun utilizandolos puros durante 24 horas; es decir, 10,000 veces mas concentrados y exponiendolos un tiempo 100 veces mayor que lo indicado por los fabricantes