Hepatitis B: epidemiological, immunological, and serological considerations emphasizing mutation

The global prevalence of hepatitis B virus is estimated to be 350 million chronic carriers, varying widely from low (<2%, as in Western Europe, North America, New Zealand, Australia, and Japan) to high (>8% as in Africa, Southeast Asia, and China). The overall prevalence in Brazil is about 8%. There are currently 7 genotypic variations, from A to G, and also 4 main surface antigen subtypes: adw, ayw, adr, and ayr. There has been great interest in identifying the geographic distribution and prognosis associated with the various genotypes and subtypes. Although the serologic test is highly sensitive and specific, it does not detect cases of mutant hepatitis B, which is increasingly common worldwide due to resistance and vaccine escape, antiviral therapy, and immunosuppression, among other causes. Alterations in surface, polymerase, X region, core, and precore genes have been described. The main mutations occur in surface and in core/precore genes, also known as occult hepatitis, since its serologic markers of active infection (HBsAg) and viral replication (HBeAg) can be negative. Thus, mutation should be suspected when serologic tests to hepatitis B show control of immunity or replication coincident with worsened clinical status and exclusion of other causes of hepatitis.

Increase in mortality due to myocardial infarction in the Brazilian city of São Paulo during winter

OBJECTIVE: To study the seasonal variation in mortality due to myocardial infarction in the city of São Paulo. METHODS: We analyzed the database of PROAIM (Programa de Aprimoramento de Informações de Mortalidade) containing the registrations of the certificates of deaths due to myocardial infarction (International Classification of Diseases, 10th edition, classification I21) of the residents of the municipality of São Paulo during 12 months (from December 1996 to November 1997). The number of deaths was corrected for a standard period of 90 days and then it was divided by the corresponding population to obtain the event rate per 10 thousand inhabitants. The magnitude of the seasonal variation, which was defined by the difference of the relative risks between the seasons with higher and lower mortality, was estimated. RESULTS: A total of 5,615 deaths due to myocardial infarction were included in the study. Sixty-one per cent occurred in the male sex, and the mean age was 68 years. The mortality rate during winter was always higher and that during summer was lower than that during the other seasons (P<0.01), independent from age and sex. Seasonal variations in deaths due to myocardial infarction was 30% in the general group, being 23% in individuals who died younger than 75 years, and 44% in the older ones. CONCLUSION: A marked seasonal variation in mortality due to myocardial infarction was observed in the city of São Paulo, with a significant increase in its magnitude and age distribution during the winter, similar to those reported in regions of North America and Europe with temperate climates.

The genera of North American plants, and a catalogue of the species, to the year 1817.By Thomas Nuttall.

v.1 1818

The genera of North American plants, and a catalogue of the species, to the year 1817.By Thomas Nuttall.

v.2 1818

Flora boreali-americana :sistens caracteres plantarum quas in America septentrionali collegit et detexit Andreas Michaux.

v.1

Flora boreali-americana :sistens caracteres plantarum quas in America septentrionali collegit et detexit Andreas Michaux.

v.2

North American flora.

v. 1, pt. 1 (1945)

North American flora.

v. 2, pt. 1 (1937)

North American flora.

v. 3, pt. 1 (1910)

North American flora.

v. 6, pt. 1 (1922)

North American flora.

v. 7, pt. 1 (1906)

North American flora.

v. 7, pt. 2 (1907)

North American flora.

v. 7, pt. 3 (1912)

North American flora.

v. 7, pt. 4 (1920)

North American flora.

v. 7, pt. 5 (1920)