The calcium-dependent protease of Loxosceles gaucho venom acts preferentially upon red cell band 3 transmembrane protein

Eighty micrograms red blood cell (RBC) ghosts from patients who had previously exhibited the cutaneous form of loxoscelism (presenting localized dermonecrosis) and the viscerocutaneous form of loxoscelism (presenting dermonecrosis, hemoglobinuria, hematuria, and jaundice) and from controls were incubated with 2.5 æg crude Loxosceles gaucho venom in 5 mM phosphate buffer, pH 7.4, at 37ºC. Among all membrane proteins, quantitative proteolysis of the important integral transmembrane protein 3 increased with venom dose and with incubation time from 30 to 120 min, as demonstrated by gel densitometry. Similar quantitative data were obtained for RBC ghosts from patients and from control subjects, a fact that argues against the possibility of genetic factors favoring the hemolytic viscerocutaneous form. These data suggest that the clinical forms may be different types of the same disease, with the viscerocutaneous form being the result of large amounts of intravascularly injected venom and the superficial form being the result of in situ venom action. Since protein 3 is a housekeeping integral membrane protein, whose genetic deficiency leads to hemolytic anemia, it is reasonable to relate it to the hemolysis which occurs in the viscerocutaneous form of loxoscelism. The venom protease responsible for the process was not inhibited after 120-min incubation by 0.2 mM paramethylsulfonyl fluoride or by 0.2 mM N-ethylmaleimide but was inhibited by 25 mM ethylenediaminetetraacetic acid (a calcium-chelating agent) in 5 mM phosphate buffer at pH 7.4, which suggests that the enzyme is a calcium-dependent metalloprotease

Leucemia mielóide aguda Ph1-positivo de novo ou crise blástica de leucemia mielóide crônica? Análise molecular e evoluçäo clínica de um caso / Ph1-positive acute myeloid leukemia de novo or chronic myeloid leukemia? Molecular analysis and clinical evolution of a case

Os autores relatam um caso de leucemia mielóide aguda (LMA) que apresentava, ao diagnóstico, basofilia no sangue periférico e cariótipo com presença do cromossomo Filadélfia (Ph1). Após um ano de tratamento com quimioterapia intensiva e em fase de remissao clínica e hematológica, a análise molecular pela técnica da reaçao em cadeia da polimerase-trasncriptase reversa (RT-PCR) revelou presença de doença residual (rearranjo b2-a2). A seguir, o paciente apresentou primeira recidiva como LMA e, após a remissao, evoluiu com quadro hematológico sugestivo de leucemia mielóide crônica (LMC) em fase crônica. Após dez meses, apresentou nova recidiva da LMA. Os autores discutem a dificuldade do diagnóstico diferencial entre LMA Ph1-positivo de novo e crise blástica mielóide como primeira manifestaçao clínica da LMC, baseados nos aspectos clínicos e moleculares.