Our results suggest that the dose-related stimulatory, permeabilizing, and toxic effects of AmB most probably have distinct mechanisms of action and may be independent of one another.

No abstract

During temperature-induced transition of the dimorphic pathogenic fungus Histoplasma capsulatum from the single yeast cell form to the multicellular mycelial form, there was an increase in intracellular cyclic adenosine 3',5'-monophosphate (cAMP) levels as well as a striking accumulation of cAMP in the medium. cAMP levels also changed during the reverse mycelium-to-yeast transition.

No abstract

The possible role of nerve on growth of embryonic parenchymal organs such as kidney was explored by measuring macromolecular synthesis (DNA, RNA, and protein and three enzymes) in aggregates of mixed suspensions of cells from dissociated chick embryo kidney and nerve tissue . One and one-half to threefold increments in net synthesis of the three different types of macromolecules were observed in the mixed aggregates of kidney and nerve cells as compared with those of single organs or mixtures of kidney with nonneural cells . The addition of nerve-growth factor (NGF) did not significantly affect the results . Increased incorporation of label was paralleled by increases in chemically measured DNA and protein, suggesting an increase in growth in the mixed kidney-nerve aggregates compared with those of single tissues. Measurements of survival rate did not indicate increased cell stability in the mixed aggregates . The activities of three enzymes, acid phosphatase, alkaline phosphatase, and lactic dehydrogenase, were also enhanced two to four times in cultures of kidney plus nerve cells . Morphologic studies indicated a high degree of reorganization of tubular structures within the reaggregates of kidney cells alone or in those mixed with nerve . In addition, radioautographs of thymidine-3 H-labeled cells in the aggregates showed a high level of DNA synthesis in the reformed tubular cells . Electron micrographs revealed the presence of large numbers of nerve fibers containing microtubules in the mixed cell aggregates . The data suggest a significant role for nerve in the growth processes of embryonic parenchymal organs.