Prevalência de adultos infectados por Leishmania leishmania chagasi entre doadores de sangue do Hemocentro Regional de Montes Claros, Minas Gerais, Brasil / Prevalence of adults infected with Leishmania (Leishmania) chagasi among blood donors of the Hemominas Foundation in Montes Claros, Minas Gerais, Brazil

O objetivo deste trabalho foi estudar a prevalência de adultos infectados por L. L. chagasi entre doadores de sangue do Hemocentro Regional de Montes Claros/MG .Realizou-se estudo epidemiológico, transversal e quantitativo, no período de 16/09/08 a 13/11/08. Participaram da pesquisa 421 doadores aptos na triagem clínica, sendo realizada imunofluorescência indireta para L.L.chagasi. Aqueles que apresentaram resultados positivos foram submetidos ao teste rápido antígeno-específico para Leishmania donovani. A análise das variáveis gênero, faixa etária, procedência, número de doações, resultados sorológicos para leishmaniose e chagas, foi realizada pelos testes estatísticos qui-quadrado (x2), x2 com tendência linear e teste Fisher. Foi considerado o nível de significância de 5 por cento (p<0,05). O perfil da amostra foi semelhante ao perfil geral dos doadores. Os participantes, em sua maioria procedentes da zona urbana (92,7 por cento), residentes em Montes Claros (67,9 por cento), homens (61,3 por cento), com faixa etária de 18 a 29 anos. Em relação aos resultados sorológicos, 23 (5,5 por cento) apresentaram positividade para imunofluorescência indireta e nenhum destes foi positivo no teste rápido. Ao comparar os resultados da imunofluorescência para leishmaniose e a sorologia Elisa chagas, dois foram positivos para ambos os testes, sendo demonstrada correlação estatística significante (p=0,003). Porém, 21 foram positivos para leishmaniose e negativos para chagas. Os resultados permitiram conhecer a prevalência da infecção por L. l. chagasi em indivíduos assintomáticos, adultos, doadores de sangue do Hemocentro Regional de Montes Claros/MG e apontam para a necessidade de maiores estudos quanto ao possível risco de transmissão transfusional da doença.

The objective of this work was to study the prevalence of adults infected by Leishmania (Leishmania) chagasi among blood donors of the Hemominas Foundation in Montes Claros, Brazil. A cross-sectional, quantitative epidemiological study was performed of 421 blood donors from September 16 2008 to November 13 2008. The L. l. chagasi indirect immunofluorescence test (RIFI) was utilized. Donors that presented with positive results in RIFI were retested using the fast immunochromatographic test (Trald). The gender, age, place of origin, number of donations, leishmania and chagas disease serum results were studied with statistical correlations being analyzed utilizing the chi-square test (x2), x2 with linear tendency and the Fisher test; a level of significance of 5 percent (p <0.05) was considered acceptable. The profile of the study sample was similar to the overall donor profile. The participants were mostly donors from urban areas (92.7 percent), living in Montes Claros (67.9 percent), men (61.3 percent) and with ages between 18 and 29 years old. In relation to the serum results, 23 (5.5 percent) were positive according to the RIFI however none of them were positive by the Trald. On comparing the results of RIFI and the chagas disease serum test (Elisa), two individuals were positive for both tests, thereby giving a statistically significant correlation (p=0.003). However the other 21 were positive only by RIFI and negative for chagas disease. The results show the prevalence of infection by L. l. chagasi in asymptomatic, adult blood donors in the Hemominas Foundation in Montes Claros, and highlight the need for further studies on the possible risk of disease transmission via blood transfusion.

Kinetic peculiarities of human tissue kallikrein: 1--substrate activation in the catalyzed hydrolysis of H-D-valyl-L-leucyl-L-arginine 4-nitroanilide and H-D-valyl-L-leucyl-L-lysine 4-nitroanilide; 2--substrate inhibition in the catalyzed hydrolysis of N alpha-p-tosyl-L-arginine methyl ester.

Hydrolysis of D-valyl-L-leucyl-L-lysine 4-nitroanilide (1), D-valyl-L-leucyl-L-arginine 4-nitroanilide (2), and N alpha-p-tosyl-L-arginine methyl ester (3) by human tissue kallikrein was studied throughout a wide range of substrate concentrations. At low substrate concentrations, the hydrolysis followed Michaelis-Menten kinetics but, at higher substrate concentrations, a deviation from Michaelis-Menten behavior was observed. With the nitroanilides, a significant increase in hydrolysis rates was observed, while with the ester, a significant decrease in hydrolysis rates was observed. The results for substrates (1) and (3) can be accounted for by a model based on the hypothesis that a second substrate molecule binds to the ES complex to produce a more active or an inactive SES complex. The deviation observed for substrate (2) can be explained as a bimolecular reaction between the enzyme-substrate complex and a free substrate molecule.