Extra structurally abnormal chromosomes (ESACs)--presentation of 10 new cases.

BACKGROUND: The goal of the presented studies as a retrospective reliability assessment of classical banding cytogenetic studies and of prognosing epicrises in a group of 14 cases, affected with additional marker chromosomes. MATERIAL AND METHODS: Having collected the study material from peripheral blood, by means of trophoblast biopsy or amniocentesis, cytogenetic preparations were obtained, allowing for pre- or postnatal evaluation of the karyotype. A panel of auxiliary cytogenetic techniques accompanied the routine CTG protocol. RESULTS: In a group of 6875 persons with recommendations to pre- or postnatal cytogenetic diagnostics, 14 (0.2%) cases of ESACs were diagnosed. In 5 cases of DA/DAPI(+) inv dup (15) as observed. A presence of polymorphic interstitial RHG(+) band was found within the marker chromosome. The measured size of that band allowed associating it with either the presence or the absence of pathological signs. In 9 cases of ESACs, DA/DAPI(-), the application of banding techniques (NOR and CBG) allowed to discover bisatellite heterochromatic ESACs in 6 cases (2 non-mosaic and 4 mosaic). In three other mosaic and non-satellite cases of ESACs, a 'genetic inactivity' of the marker chromosome was observed in one case, while a 'genetic activity' was ascertained in two cases. The 'activity' of marker chromosomes was studied by means of replication banding techniques. CONCLUSIONS: At the time of the outburst of molecular techniques, still up-to-date is the use of classical banding techniques and of the replication techniques, allowing DNA replication kinetics studies at the level of single band.

A human breast tumor cell line (BT-474) that supports mouse mammary tumor virus replication.

A human breast tumor cell line BT-474 derived from an invasive ductal carcinoma was experimentally infected in vitro with a mouse mammary tumor virus from the TIII strain (RIII-MuMTV). The virus that replicated in the human cells was characterized as a mouse virus by immunofluorescence, electron microscopy and the presence of a specific RNA-directed DNA polymerase. The cells themselves were human as per the karyotype and isoenzyme migration patterns. It is concluded that human cells are susceptible to the mouse mammary tumor virus and can, eventually, support its replication.

Isolation of two human tumor epithelial cell lines from solid breast carcinomas.

Most of the available human breast tumor cell lines have been derived from pleural effusions. The two cell lines herein described, BT-474 and BT-483, were derived from solid, invasive ductal breast carcinomas. Both are epithelial and neoplastic as judged by their general morphology, their fine structure, and their ability to produce growing nodules in nude mice and colonies in soft agar and methocel. BT-474 and BT-483 are human as expressed by chromosome morphology and aneuploid with a modal number of 55 and 72 chromosomes, respectively. Trypsin-Giemsa banding did not reveal the presence of obvious HeLa markers, and the glucose 6-phosphate dehydrogenase electrophoretic migration pattern was of the B-type. Furthermore, the migration of lactic dehydrogenase, malic dehydrogenase, and 6-phosphogluconate dehydrogenase isoenzymes was consistent with a human pattern and different from that of the mouse, rat, or hamster. Quarterly tests to detect the presence of aerobic and anaerobic mycoplasmas were repeatedly negative. A culture medium containing insulin, increased amounts of amino acids, vitamins, and glucose facilitated the isolation of the tumor cells. Cell replication was maintained with 10% fetal calf serum absorbed with activated charcoal and dextran. No production of alpha-lactalbumin was detected by radioimmunoassays, but high levels of progesterone receptors were found in both cell lines.