Primary culture of mouse mammary tumor epithelial cells embedded in collagen gels

Mammary tumor epithelial cells from BALB/cfC3H mice were dispersely embedded inside the collagen gels in Ham's F-12 medium containing horse serum. A sustained cell growth leading to a 5- to 10-fold increase in cell number over initial level was observed in less than 2 weeks. The extent of this growth was found to be dependent on serum concentration. However, addition of various protein and steroid hormones, both singly and in combination, to low-serum-containing medium failed to achieve a comparable level of growth to that promoted by higher serum concentration. Mammary tumor cells can now be consistently propagated in primary culture.     

Stereospecific reactivation of human brain and erythrocyte acetylcholinesterase inhibited by 1,2,2-trimethylpropyl methylphosphonofluoridate (soman)

Human erythrocyte and brain acetylcholinesterase are preferentially inhibited by the P(-)-isomers of C(+/-)P(+/-)-soman. The enzymes inhibited by the P(-)-isomers behave similarly with respect to oxime-induced reactivation and aging. HI-6 is the best reactivator for C(+)P(-)-soman-inhibited acetylcholinesterases. Oxime-induced reactivation of the C(-)P(-)-soman-inhibited acetylcholinesterases is much more difficult to achieve.     

Concurrent disappearance of N-acylethanolamine glycerophospholipids and phagolysosomes enriched in N-acylethanolamine glycerophospholipids as Dictyostelium discoideum cells aggregate

As the cellular slime mold, Dictyostelium discoideum, undergoes development, a phospholipid fraction containing 80% N-acylethanolamine glycerophospholipids (NAEGPs) and 20% acylphosphatidylglycerol (APG) disappears during the aggregation stage. In this study, the subcellular distribution of that NAEGP phospholipid fraction and the precise time period of disappearance of the fraction were determined. The content of the NAEGP fraction was determined in aggregating cells at 2-h intervals from the beginning of the developmental phase through 14 h, when the cells were completely aggregated. The NAEGP fraction comprised about 8% of the phospholipids in amoebae just starting the development cycle and about 12% in cells between 2 and 6 h of development; then its level decreased until it could not be detected at 12 and 14 h of development. The mole percentage of the total lipid phosphate in the NAEGP fraction was determined in isolated subcellular organelles. The phagolysosomes were enriched in the NAEGP fraction 1.7-2-fold over the level found in the amoebae and about 8-fold over the level in fractions highly enriched in the plasma membrane, mitochondria or peroxisomes. The content of phagolysosomes was determined by electron microscopy of aggregating cells. The amoebae contained large amounts of phagolysosomes up to 6 h of development, and then they gradually disappeared between 6 and 12 h of development. This combination of quantitative phospholipid analysis, subcellular organelle isolation and electron microscopy has revealed that in D. discoideum amoebae, the phagolysosomes were selectively enriched in the NAEGP fraction and both the NAEGP-enriched phagolysosomes and the NAEGPs disappeared concurrently between 6 and 12 h of development.     

Genotoxicity of ptaquiloside, a bracken carcinogen, in the hepatocyte primary culture/DNA-repair test

The genotoxicity of ptaquiloside (PT), recently isolated from bracken fern and shown to be carcinogenic, was examined by means of the hepatocyte primary culture/DNA-repair test. PT elicited clear unscheduled DNA synthesis with a dose-response effect. The result indicates that PT is a genotoxic carcinogen.