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Cytogenetic analysis of tumor cells from a human malignant melanoma was performed on both the primary tumor colony-forming cells and a cell line (HA-A) established subsequently from the clonogenic population. Chromosome-banding analysis demonstrated identical karyotypic alterations in both the tumor colony-forming cells and the HA-A cell line, documenting their origin from a common precursor. The most distinctive chromosome alterations shared between tumor colony-forming cells and the HA-A cell line were double-minute bodies (DMs) and a homogeneously staining region (HSR) on chromosome 7 at band p22. This represents the first observation of DMs or HSRs in cells from a human malignant melanoma. The frequency of HSR-bearing cells observed in the original tumor was less than 1%, while DM-containing cells were present in greater than 90% of all cells examined. In contrast, serial chromosome harvests at early passage of the HA-A cell line revealed positive selection for HSR-bearing cells with concomitant loss of DM-containing cells after increasing time in vitro. Following the ninth serial passage in vitro, HSRs were observed in 100% of cells with DMs no longer observed in the HA-A cell line. The finding of an HSR-bearing marker in the original tumor sample supports the view that HSRs are not an artifact of in vitro monolayer growth. However, our results demonstrate that the frequency of HSR-bearing cells within established cell lines may reflect in vitro selection and therefore not accurately reflect the frequency of this population in vivo.

Infiltrating ductal carcinoma is an extremely rare neoplasm in the teenage or pre-teenage child. Routine pediatric physical examination should include careful examination of the breast and all palpable masses should be excised. Carcinoma occurring in the prepubertal child carries an improved prognosis particularly if the tumor stains PAS-positive. Carcinoma occurring in the postpubertal teenager probably carries the same prognosis as that in the adult and should be treated in a similar manner. The authors discuss such a case occurring in a 13-year-old girl.

Technological advances in the study of chromosomes from human and experimental cancers are occurring rapidly. Molecular cytogenetic techniques for in situ hybridization, as well as chromosome sorting and even karyotyping via flow cytometry (both described elsewhere within this volume), are important developing areas receiving considerable study. However, there currently remains a significant need for routine karyotyping of mammalian cells. It is hoped that the methods provided in this chapter will be of help in assisting somatic cell geneticists to identify chromosome changes in mammalian cell cultures.

A K-band to X-band converter has been developed and placed in operation at a field site. The crystal is mounted in a modified K-band crystal mount. Several crystals were calibrated for field use. The measured parameters of bandwidth and conversion loss were 200 Mc and 12 to 15 db, respectively. A minimum detectable signal of -72 dbm was measured using an X-band traveling-wave tube as the first i-f amplifier.