Przegla̧d epidemiologiczny
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The association between maternal smoking and retarded fetal grow was first time described in 1957, and now is well know. In addition smoking during pregnancy increases risk of spontaneous abortion, placenta previa, abruptio placenta, preterm premature rupture of membranes, stillbirth, preterm delivery and congenital malformations. The risk for most of these conditions has been found to increase with the number of cigarettes smoked and on the other hand women who stopped smoking during pregnancy are at the lower risk for most of those pathologies.
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PCT is a new highly sensitive and specific marker of bacterial and fungi infection--to be used in differential diagnosis at Infectious Diseases Departments. Author in this paper presents structure and mechanism of stimulation of PCT as a factor of "early infection's fase" for many infectious agents: bacteria, fungi, viruses and parasites. PCT may be found useful in diagnosing diseases; for ex.: sepsis, meningitis, inflammation of respiratory system, spontaneous bacterial peritonitis (SPB) and other local inflammatory foci (otitis media, endocarditis). PCT level is low in systemic inflammatory response syndrome (SIRS) and multiorgan dysfunction syndrome (MODS) of non-infectious origin (< 0.5 ng/ml), medium in case of localized infections (1.0-2.0 ng/ml) and in severe cases of disseminated infections (sepsis-->SIRS-->MODS) high (approximately 20 ng/ml).
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2367 cases of meningitis and 571 of encephalitis were reported in Poland in 2001. Among meningitis 1324 cases were classified as viral and 838 as bacterial. ⋯ Among them Neisseria meningitidis was found in 106 cases, Haemophilus influenzae in 75 cases and Streptococcus pneumoniae in 99 cases. As in the past type B was the predominant type of N. meningitidis cultured from patients. 210 cases of tick borne encephalitis were reported in Poland in 2001, most of them from endemic areas of north-eastern part of the country.
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Problems with sample selection in epidemiological studies starts with the definition of representativeness of the sample. The definition of representativeness as a "miniature of the population" is impractical, especially for very rare disease, and not suitable for certain types of epidemiological studies. ⋯ The article reviews different meanings of representativeness used directly or implicitly in epidemiological and statistical studies and gives examples of certain methods of sample selection for the specific purposes including matching in design. Some important sources of selection bias and methods of avoiding it are also addressed in this article.