The effect of aeration and metabolic inhibitors on resistance to amphotericin in starved cultures of Candida albicans.

The development of resistance to amphotericin methyl ester, measured in terms of the amount of drug required to induce a standard rate of release of K+ from suspensions of washed organisms, has been followed in Candida albicans in starved cultures under controlled conditions of aeration, stirring and temperature. Resistance develops at a rate which increases with the rate of aeration, limited by the onset of damage due to turbulence. Resistance decreases rapidly if gassing with N2 is substituted for aeration, but sensitivity does not reach that of exponentially growing cells. Resumption of aeration is followed by a slow recovery of resistance. The addition of inhibitors of protein synthesis (trichodermin, verrucarin) or uncoupling agents (2,4-dinitrophenol, sodium azide) at the beginning of starvation results in an increased rate of development of resistance. Adding inhibitors at a later stage, when resistance has developed after 72 h aeration, does not affect the decrease in resistance produced by gassing with N2 but the presence of trichodermin or verrucarin delays the recovery of resistance o     

Measuring percent lymphocytes by flow cytometry to calculate absolute lymphocyte subset counts for HIV+ specimens.

A comparison was made of lymphocyte percentages from an automated hematology analyzer (ELT 15) vs. a fluorescence flow cytometer (Cytofluorograf). The hematology values were consistently higher than the flow (by greater than 10% for 13 of 50 HIV+ specimens). The findings were similar to three other pairings: H*1 vs. Cytofluorograf, Cell Dyn 3000 vs. Cytofluorograf, and Cell Dyn 3000 vs. EPICS Profile. In another comparison manual percent lymphocytes matched much better with flow values. Factors of sample preparation and instrument analysis as they relate to nonrandom cell loss and lymphocyte resolution are examined.