Arsenic methylation and lung and bladder cancer in a case-control study in northern Chile.

In humans, ingested inorganic arsenic is metabolized to monomethylarsenic (MMA) then to dimethylarsenic (DMA), although this process is not complete in most people. The trivalent form of MMA is highly toxic in vitro and previous studies have identified associations between the proportion of urinary arsenic as MMA (%MMA) and several arsenic-related diseases. To date, however, relatively little is known about its role in lung cancer, the most common cause of arsenic-related death, or about its impacts on people drinking water with lower arsenic concentrations (e.g., <200µg/L). In this study, urinary arsenic metabolites were measured in 94 lung and 117 bladder cancer cases and 347 population-based controls from areas in northern Chile with a wide range of drinking water arsenic concentrations. Lung cancer odds ratios adjusted for age, sex, and smoking by increasing tertiles of %MMA were 1.00, 1.91 (95% confidence interval (CI), 0.99-3.67), and 3.26 (1.76-6.04) (p-trend <0.001). Corresponding odds ratios for bladder cancer were 1.00, 1.81 (1.06-3.11), and 2.02 (1.15-3.54) (p-trend <0.001). In analyses confined to subjects only with arsenic water concentrations <200µg/L (median=60µg/L), lung and bladder cancer odds ratios for subjects in the upper tertile of %MMA compared to subjects in the lower two tertiles were 2.48 (1.08-5.68) and 2.37 (1.01-5.57), respectively. Overall, these findings provide evidence that inter-individual differences in arsenic metabolism may be an important risk factor for arsenic-related lung cancer, and may play a role in cancer risks among people exposed to relatively low arsenic water concentrations.

Arsenic, tobacco smoke, and occupation: associations of multiple agents with lung and bladder cancer.

BACKGROUND: Millions of people worldwide are exposed to arsenic in drinking water, and many are likely coexposed to other agents that could substantially increase their risks of arsenic-related cancer. METHODS: We performed a case-control study of multiple chemical exposures in 538 lung and bladder cancer cases and 640 controls in northern Chile, an area with formerly high drinking water arsenic concentrations. Detailed information was collected on lifetime arsenic exposure, smoking, secondhand smoke, and other known or suspected carcinogens, including asbestos, silica, and wood dust. RESULTS: Very high lung and bladder cancer odds ratios (ORs), and evidence of greater than additive effects, were seen in people exposed to arsenic concentrations >335 µg/L and who were tobacco smokers (OR = 16, 95% confidence interval = 6.5-40 for lung cancer; and OR = 23 [8.2-66] for bladder cancer; Rothman Synergy Indices = 4.0 [1.7-9.4] and 2.0 [0.92-4.5], respectively). Evidence of greater than additive effects were also seen in people coexposed to arsenic and secondhand tobacco smoke and several other known or suspected carcinogens, including asbestos, silica, and wood dust. CONCLUSIONS: These findings suggest that people coexposed to arsenic and other known or suspected carcinogens have very high risks of lung or bladder cancer.

Morfometría de los Nervios Tibial y Plantares / Morphometry of the Tibial and Plantar Nerves

La inervación motora de los músculos del pie y susvariaciones anatómicasson importantes para el correcto diagnóstico de las lesiones de nervios periféricos y su tratamiento posterior. Con frecuencia, el pie es afectado por accidentes y la microcirugía reparadora requiere de abundante y detallada información anatómica para efectuar con éxito sus procedimientos. La falta de información morfométrica y estereológica de los nervios destinados a la musculatura del pie, nos motivó a plantear esta investigación. Se estudiaron 5 pies de cadáveres, adultos, en los cuales se disecaron la terminación del nervio tibial y el origen de los nervios plantares, medial y lateral. A través de cortes histológicos transversales de los nervios tibial y plantares, obtuvimos información cuantitativa sobre medidas morfométricas (número de fascículos, área de los fascículos, número de fibras por fascículo, número de fibras por nervio). Los resultados obtenidos fueron tratados estadísticamente y se registraron fotográficamente las muestras más representativas. El número de fascículos en el nervio tibial varió entre 19 y 39 con un promedio de 28,6 (D.S. 7.13), en los nervios plantares laterales varió entre 8 y 18 con un promedio de 14,8 (D.S. 3.96) y en los nervios plantares mediales varió entre 9 y 19 con un promedio de 12,4 (D.S. 3,91). El área promedio de los fascículos en los nervios tibial, plantar medial y plantar lateral fue de 3,66mm², 1,8mm² y 1,48 mm², respectivamente. Con los datos obtenidos esperamos contribuir al conocimiento morfológico y morfométrico de las estructuras nerviosas del pie, sirviendo de apoyo anatómico y quirúrgico.

Motor innervations of foot muscles and anatomic variations are very important for the correct diagnose of the lesions of peripheral nerves and their afterward treatment. Frequently, the foot is affected by accidents and reparatory microsurgery, which requires abundant and detailed anatomic information to be able to carry out successfully all necessary procedures. Lack of morphometric and stereological facts of the nerves of foot muscles, motivated us to execute this research. Here, five adult corpse feet were studied, where the tibial termination nerves, the origin of the medial and lateral plantar nerves. With transversal histological cuts of plantar and tibial nerves, quantitative information was obtained on morphometric measures (fascicule numbers, fascicule areas, number of fibers per fascicule, number of fibers per nerve). The obtained results were statistically analyzed and the most representative samples, photographically registered. The number of fascicules in the tibiae nerve varied between 19 to 39, with an average of 28.6 (D.S. 7.13), in the lateral plantar nerves it varied between 8 to 18, with an average of 14,8 (D.S. 3.96) and in the medial plantar nerves, it varied between 9 to 19, with an average of 12,4 (D.S. 3,91). The average area of the fascicules, in the tibia, medial plantar and plantar lateral nerves, was 3,66mm², 1,8mm² and 1,48 mm². With the obtained data, it is expected to contribute to morphological and morphometric knowledge of foot nerve structure, which can be used for anatomicsustain, as well as chirurgic support.

Estudios histológico e histoquímico del epidídimo del conejo: oryctolagus cuniculus / Histologic and histochemical studies of the epididymis of rabbit: oryctogus cuniculus

En el trayecto por el epidídimo, los espermatozoides adquieren su capacidad fecundante y sus características de motilidad traslativa, que se relaciona con glicoproteínas de probable secreción epididimaria. El objetivo de nuestro trabajo fue describir la morfología del epidídimo del conejo y estudiar sus características histológicas e histoquímicas. Utilizamos 6 conejos (Oryctolagus cuniculus) híbridos, machos y sexualmente maduros, obtenidos del Bioterio de la Facultad de Medicina de la Universidad de la Frontera, Temuco, Chile. A los cortes histológicos obtenidos de la disección y procesamiento de los epidídimos de los conejos, se les realizaron las siguientes tinciones. H-E, Pas diastasa, Azul alcián, Tricrómico de Masson, Van Gieson, Verhoff para fibras elásticas y Reticulina de Gomori. El epidídimo de conejo es un largo conducto contorneado que presenta tres regiones: cabeza, cuerpo y cola, divididas por proyecciones de su albugínea. La forma de los conductos fue regular e isodiamétrica en la cabeza, a irregular y anisodiamétrica en la cola. Se observó que el tejido interductal era conjuntivo laxo regular, intensamente vascularizado, y que en la zona periductal existían células musculares lisas circundantes y una fina red de fibras reticulares. El epitelio era pseudoestratificado cilíndrico simple, aparentemente disminuyendo en altura hacia la cola y formado por células principales, basales y de citoplasma cromófobo o células halo, que se observaron ocacionalmente. La zona apical de las células principales al igual que la lámina basal del epitelio, presentaron reacción Pas positiva, que fue más intensa en la cola