somes in Disease," Jorge J.Yunis. The chapter by Ohno is probably the most valuable, both because it describes a still neglected technique with which only a few are expert, and because it is provocative as well as informative. The variations in methods used for several forms of tissue culture and other techniques described here are almost infinite. This has posed a major problem for each of the...

Many mechanisms have been proposed to explain cisplatin resistance, suggesting that this phenomenon is multifactorial. In an attempt to define the chromosome(s) responsible for cisplatin resistance in the human ovar ian carcinoma 2008/C13* cell lines, somatic cell hybrids were obtained following fusion of the cisplatin-resistant 2008/C13* cells with an A9 rodent fibroblast cell line. The hybrid...

In conclusion, the composition of cen-tromeric particles—octameric, hexameric, tetrameric (tetrasomes or hemisomes), or a combination of these—as well as the mechanisms by which centromeric chro-matin acquires stable positive supercoil-ing certainly need further clarification. However, the results of Furuyama and Henikoff confirm that nucleosomes are not mere repetitive " canonical " chroma-tin...

Peripheral blood monocytes were isolated from normal human donors by separation on a continuous Percoli gradient and adherence to yield preparations of blood monocytes with a high degree of purity (> 99%). The monocytes were incubated in vitro with medium alone or with multilamellar liposomes that contained either a lipophilic derivative of muramyl dipeptide, muramyl tripeptide (MTP-PE), or med...

SUMMARY It has been demonstrated that solid hepatoma lysosomes lack hyaluronidase activity, whereas normal rat liver lyso somes contain a high level of this enzyme. This result was also found with lysosomes from an ascites hepatoma, Walker carcinoma 256, and virally transformed BHK cells. In contrast, 0-yV-acetylglucosaminidase activity was shown to be present in lysosomes from tumor cells, alt...

Poly(dA)´poly(dT) tracts are common and often found upstream of genes in eukaryotes. It has been suggested that poly(dA)´poly(dT) promotes transcription in vivo by affecting nucleosome formation. On the other hand, in vitro studies show that poly(dA)´poly(dT) can be easily incorporated into nucleosomes. Therefore, the roles of these tracts in nucleosome organization in vivo remain to be establi...