ABSTRACT
Selenium (Se) is an antioxidant element that protects against cellular damage by reactive oxygen species. Therefore, total serum Se concentration may reflect protection during the development of cirrhosis, an oxidative stress-related disease. We hypothesized that serum Se levels are diminished in cirrhotic patients due to their enhanced oxidative stress, and serum Se levels are reduced the most in patients with the highest severity of cirrhosis. A case-control study was performed to determine whether cirrhosis is associated with changes in serum Se levels. Blood samples from 30 healthy controls and 93 cirrhotic patients were analyzed for total serum Se by hydride generation atomic absorption spectrometry. The Child-Pugh index score was used to evaluate the severity of liver disease. The mean serum Se concentration was significantly lower in patients vs controls (0.721 ± 0.239 vs 0.926 ± 0.241 µmol/L; P = .001). Mean serum Se levels were not significantly lower in patients with higher severity of cirrhosis (0.691 ± 0.229 vs 0.755 ± 0.255 µmol/L; P = .144). A positive and significant correlation was found between age and serum Se levels in patients (r = 0.277, P = .007). Patients showed significant sex differences in serum Se level (higher in male) and severity index (higher in female). The significantly decreased serum Se level in patients indicates that the Se component of the antioxidant system is severely impaired in cirrhosis. However, serum Se levels were not influenced by the severity of the disease.
Subject(s)
Antioxidants/metabolism , Liver Cirrhosis/blood , Selenium/blood , Adult , Case-Control Studies , Female , Humans , Liver Cirrhosis/classification , Male , Middle Aged , Oxidative Stress , Severity of Illness Index , Sex Factors , Spectrophotometry, AtomicABSTRACT
Objetivo: La primera pregunta que un estadístico ha de responder cuando se diseña un muestreo es sobre el tamaño de muestra requerido para estimar un parámetro poblacional con una precisión específica.Este trabajo busca la respuesta a esta pregunta y muestra procedimientos prácticos de selección de una muestra en muestreo aleatorio simple, muestreo sistemático y muestreo estratificado. Para que los conceptos básicos expuestos en este trabajo tengan aplicación directa en la práctica, se han ilustrado con ejemplos en censos actuales de Oficinas de Farmacia en Andalucía (AU)
Objective: Almost the first question which a statistician is called upon to answer in planning a sample survey is about the size of the sample required for estimating the population parameter with a specified precision. This paper finds the answer to this question and shows practical procedures of selecting a random sample in simple random sampling, systematic sampling and stratified sampling. In order that the basic concepts presented in this paper should be of direct assistance in practice, it is illustrated with examples of actual census of Chemist's in Andalucian (AU)
