RESUMEN
Concentrates of the epimastigote stage of Trypanosoma cruzi stocks derived from single cell clones and cultured under identical conditions display a spectrum of 'colors' varying from dark brown to milk white. The color of the concentrate is reproducible for a parasite stock. An essential component of the culture medium for epimastigote growth is hemin, an iron-containing compound. Consequently, it seemed possible that the color spectrum of the epimastigote stocks reflected differences in the uptake, concentration or utilization of iron. This report describes the quantitative studies utilizing electron probe X-ray elemental mapping, energy dispersive X-ray microanalysis, and energy dispersive X-ray fluorescence spectrometry of the epimastigote stage of two T. cruzi stocks (CA-I/72 and HO-3/15) which display extreme color differences. Striking and statistically significant quantitative differences were found in the levels of Fe, Zn, and K between the two stocks. On the basis of atomic ratios, the CA-I/72 stock contains approximately two-fold more Fe per cell than the HO-3/15 stock. However, in the case of Zn the ratio is reversed; the HO-3/15 stock contains approximately two-fold more Zn per cell than the CA-I/72 stock. The marked inter-stock differences which exist in the levels of several elements could modulate the pathogenicity, survival, or adaptability of T. cruzi and, consequently, be important factors in our understanding of the complex problem of Chagas' disease.
Asunto(s)
Trypanosoma cruzi/análisis , Animales , Color , Microanálisis por Sonda Electrónica , Trypanosoma cruzi/ultraestructuraAsunto(s)
Hígado/análisis , Metales/análisis , Plantas/análisis , Animales , Bovinos , Análisis Espectral/métodos , Rayos XRESUMEN
Preparation of samples of known concentration of hydrogen fluoride, arsine and phosgene in air from 0.5 to 10 times the TLV is described. These are required to evaluate and calibrate analytical monitoring devices used for measuring these gases in work atmospheres. Dynamic gas-blending systems have been constructed and evaluated at the National Bureau of Standards for preparing these samples. Measurements to estimate the long term concentration stability of these gases are also included.