Chagasic infection in blood donors from hospitals in endemic regions of Chile (1982-1987). Epidemiological impact of the problem]

Chagas' disease, produced by Trypanosoma cruzi and transmitted by hematophagous triatomine bugs, exists in the Western Hemisphere from the south-western United States to central Chile and Argentina. It exists in rural and periurban sections of the northern half of Chile, with a prevalence of 16.9%. Constant rural-urban migrations have contributed to its spreading to urban sections. In order to investigate the impact of these migrations on the population susceptible of being blood donors and the probable increasing of the risk of T. cruzi transmission by blood transfusion, epidemiological surveys were carried out in donors from 22 hospitals located in the northern half of Chile. By means of an indirect hemagglutination test for Chagas' disease 16,841 blood donors were examined, arising a 2.7% of positivity, percentage that permitted to estimate that 126,477 potential blood donors infected with T. cruzi should be in the urban sections studied. These facts strengthen the need that serology for Chagas' disease must be routinely performed in endemic regions of the country, to adopt or reinforce the pertinent preventive measures.     

Beta-galactosidase fused to the hydrophobic domain of cytochrome b5 spontaneously associates with liposomes

Since liver microsomal cytochrome b5 spontaneously associates with liposomes and membranes by means of its C-terminal hydrophobic domain (HP), chimeric proteins containing HP prepared by genetic fusion might also spontaneously associate with liposomes or cellular membranes. Synthetic DNA corresponding to the hydrophobic domain of cytochrome b5 was enzymatically fused in-frame to cloned DNA corresponding to the C-terminus of the Escherichia coli enzyme, beta-galactosidase. This protein, LacZ:HP, synthesized in E. coli and purified from a crude E. coli membrane extract, was shown to spontaneously associated with liposomes, as does cytochrome b5. Association is rapid and stable in the presence of salt and high pH and the fusion protein behaves as an integral membrane protein. LacZ:HP can be readily and extensively purified from crude extracts by association with liposomes and this procedure may provide a convenient purification scheme for proteins not otherwise readily purified, for example polypeptides from cloned gene fragments to be used for antibody production. These hybrid proteins may represent a new potentially useful class of polypeptides capable of hydrophobic interactions with membranes.     

Electrocardiographic alterations in persons with a positive serology for toxoplasmosis]

To each of 11,161 randomly taken people from urban and peri-urban localities of the first seven regions of Chile (geographic area of distribution of Chagas' disease in the country), with negative serology for Chagas' disease, an indirect hemagglutination test (IHAT) for toxoplasmosis and an EKG were practiced. The IHAT for toxoplasmosis resulted positive in 3,519 individuals (31.5%). The EKG showed alterations in 10.9% of the IHAT positive individuals and in 7.9% of the IHAT negative ones. This difference between the proportion of altered EKG in IHAT positive people and altered EKG in those with negative IHAT is statistically significative with p < 0.001. These results suggest the convenience of considering toxoplasmosis as a cause of chronic myocardiopathy in epidemiological studies on Chagas' disease, since not discard the presence of Toxoplasma gondii infection should overvaluete the magnitude of the impact of Trypanosoma cruzi in the genesis of such a myocardiopathy.