Takanobu Imanaka

Ultrastructural analysis of membrane-bound polysomes in human myeloma cells

SummaryWe prepared ultra-thin sections of human myeloma cells, in which the rER was cut tangentially, and studied the make-up and distribution of membrane-bound polysomes electronmicroscopically. In IgG myeloma large and small polysomes were detected. The polysome distribution curve showed a high peak at 7 ribosomes and a lower peak at 17–18 ribosomes. IgA-, IgD- and IgE myeloma, as well as macroglobulinemia, showed peaks at 7 and 13 ribosomes. BJP myeloma manifested a sharp peak only at 7 ribosomes. Our results suggest that BJP myeloma has only small polysomes participating in L-chain synthesis, while the other myelomas exhibited large and small polysomes participating in H- and L-chain synthesis, respectively. The quantitative ratio of small and large polysomes was determined on the basis of an analytically corrected direct count.

Non-Hodgkin's lymphomas with chromosomal translocations involving 3q27 band and immunoglobulin gene loci: Report of two cases

Two cases of non-Hodgkins lymphoma (NHL) of B-cell origin with reciprocal chromosome translocations involving the 3q27 band and loci for the immunoglobulin genes are described. In case 1, [t(3;14)(q27;q32)], the 14q32 band for the immunoglobulin heavy chain gene was involved, and in case 2, [t(3;22)(q27;q11)], the reciprocal breakpoint was the 22q11 band where the immunoglobulin lambda light chain gene is located. Although the two patients shared some clinical features, the lymphomas varied in histologic phenotypes; in case 1, the lymphoma being a diffuse large cell subtype, whereas in case 2, the lymphoma being the high grade small noncleaved cell lymphoma. Thus, the consistent association of the 3q27 translocation with a specific subtype of NHL remains to be determined. Southern blot analysis of the lymphoma cells from the two patients showed rearrangements and deletions in immunoglobulin genes with features which cannot be explained by normal immunoglobulin-generating mechanisms and which suggest that the translocations involved these loci at the molecular level. Cloning of the breakpoint using DNA probes from the immunoglobulin genes would prove a novel oncogene at the 3q27 band.