Full Text Available É apresentado um caso de meningopatia leucêmica com um quadro de hipertensão intracraniana, que surgiu 18 meses após a remissão clínica e hematológica de leucemia aguda. A terapêutica por via intratecal com o Amethopterin, na dose de 5 mg, repetida 6 vêzes e com intervalos de 5 a 7 dias, proporcionou melhora clínica imediata e normalização do LCR após dois meses de tratamento. O paciente continuou bem clinicamente e com o sangue e o LCR normais após 4 meses de observação. A experiência dêste caso e daqueles citados na literatura justificam que todos os pacientes leucêmicos sejam cuidadosamente observados a fim de se poder diagnosticar precocemente uma complicação neurológica, para que o tratamento adequado possa permitir maior sobrevida. O exame do LCR tem importância decisiva no diagnóstico desta complicação; ulteriormente, os exames seriados do LCR orientam a duração e a intensidade do tratamento. A padronização do tratamento das complicações neurológicas das leucemias constitui campo aberto às investigações.
JOHNSON, A H; HUTCHISON, D J
Johnson, Alva H. (Sloan-Kettering Institute for Cancer Research, Rye, N.Y.), and Dorris J. Hutchison. Folic acid metabolism in antifolic-resistant mutants of Streptococcus faecalis. J. Bacteriol. 87:786-791. 1964.-Streptococcus faecalis ATCC 8043 and three of its mutants resistant to amethopterin were compared for their quantitative requirements for serine, purines, and thymine; for their quantitative requirements of folic acid (FA) for the synthesis de novo of serine, purines, and thymine; for the susceptibility to amethopterin of each pathway; and for the relative capacity of resting cells of each culture to synthesize N(5)-formyltetrahydrofolate (5-CHOFAH(4)) from FA and serine or FA and formate. The mutants were found to be both qualitatively and quantitatively different from one another and from the wild strain. The growth conditions, specifically the composition of the medium in which each mutant strain was selected, had a marked effect on the metabolic capacities of the mutants. The ability to synthesize serine, purines, and thymine, as observed from the FA requirements, directly reflected the level of resistance of each pathway to amethopterin. The resistant mutants were more efficient than the wild strain in the formation of 5-CHOFAH(4) from FA and formate and, furthermore, this formate activation paralleled their capacities in the synthesis de novo of serine. Alterations in purine and thymine biosyntheses were also observed.
ALBRECHT, A M; HUTCHISON, D J
Albrecht, Alberta M. (Sloan-Kettering Institute for Cancer Research, New York, N.Y.), and Dorris J. Hutchison. Repression by adenine of the formyltetrahydrofolate synthetase in an antifolic-resistant mutant of Streptococcus faecalis. J. Bacteriol. 87:792-798. 1964.-In an amethopterin-resistant mutant of Streptococcus faecalis ATCC 8043 under cultivation conditions requiring purine synthesis de novo, both the dihydrofolate reductase and the formyltetrahydrofolate synthetase were formed as constant fractions of the total protein synthesized during the exponential phase of growth. When excess adenine was added to the medium, the rate of formation of the synthetase was markedly decreased, i.e., repressed. Under these latter conditions, the synthesis of the reductase proceeded at a rate equal to that observed in the absence of adenine. The repressibility of the synthetase by adenine was demonstrated also by the decrease in rate of synthetase formation upon the addition of adenine to a culture actively synthesizing this enzyme. Guanine and hypoxanthine, like adenine, also repressed the synthetase; exogenous xanthine was less effective. Neither of the pyrimidines, thymine and uracil, at approximately 1 mug/ml, interfered with synthesis of the two enzymes.