Cyclophosphamide-induced oncogenic transformation, chromosomal breakage, and sister chromatid exchange following microsomal activation

Cyclophosphamide, an extensively used cancer chemotherapeutic agent, requires metabolic activation through a mixed-function oxygenase system. The capacity of this agent to produce oncogenic transformation and chromosomal damage, including increases in sister chromatid exchanges, was investigated in cell culture with or without an exogenous liver metabolic activation system. No oncogenic transformation or chromosomal aberrations were produced by cyclophosphamide in the absence of metabolic activation, whereas significant transformation, chromosomal breaks, and increases in sister chromatid exchanges were observed when the activation system was incorporated into the assays. The oncogenic transformation and chromosomal changes were completely eliminated by removing glucose 6-phosphate and nicotinamide adenine dinucleotide phosphate from the metabolic generating system. These studies emphasize the necessity to incorporate some activation procedure into short-term assays used for evaluating the mutagenic and/or oncogenic potential of various chemicals.

Response of hematopoietic cell lines derived from patients with Down's syndrome and from normal individuals to mitomycin C and caffeine

Eight human hematopoietic cell lines, five derived from blood of patients with Down's syndrome (DS) and three from normal persons, were treated with mitomycin C (MC) and caffeine at various dose levels and for various durations. An increased rate of chromosome aberrations was found in all treated cultures. The extent of aberrations was correlated with the dose levels and duration; no difference occurred in sensitivity between the group of DS and normal lines at all dose levels and for all durations. Studies on the effect of MC severely reduced cell viability, but no difference was found in the rate of reduction of viable cell counts between DS and normal lines. Inhibition of mitoses by MC in DS lines, however, seemed stronger than that in normal lines.

Induction of morphological transformation in mouse C3H/10T1/2 clone 8 cells and chromosomal damage in hamster A(T1)C1-3 cells by cancer chemotherapeutic agents

Various cancer chemotherapeutic agents including alkylating agents, antimetabolites, and antibiotics or natural products were studied for their ability to produce morphological transformation in the C3H/10T1/2 clone 8 mouse cell line and chromosomal damage in the A(T1)C1-3 hamster cell line following a 24-hr exposure of each agent at different concentrations. Those drugs that were known to be carcinogenic in vivo also produced morphological transformation and chromosomal damage, whereas those agents that have not been shown to be carcinogenic in vivo produced neither transformation nor chromosomal lesions. The concentrations used for these studies were in general similar to those actually reached in the plasma of patients treated with these same drugs for malignant, as well as certain nonmalignant, conditions.

Morphology, growth, chromosomal pattern and fibrinolytic activity of two new human neuroblastoma cell lines

Neuroblastoma cell lines LA-N-1 and LA-N-2 were extablished from neuroblastoma cells in the bone marrow and in the primary tumor, respectively, of two children with metastatic neuroblastoma. Morphology, growth in vitro and in athymic nude mice, chromosomal patter, and fibrinolytic activity of these cell lines and of previously extablished human neuroblastoma cell lines IMR-32, SK-N-MC, and SK-N-SH were compared. Most LA-N-1 cells were tear-drop shaped, small cells with processes; they tended to grow in clusters. LA-N-2 was comprised of elongated cells and small round cells, the latter growing in dense clumps on the former. Electron microscopy revealed numerous cytoplasmic dense cores in many LA-N-1 cells but none in LA-N-2 CELLS. During logarithmic growth in vitro, doubling times for LA-N-1, LA-N-2, SK-N-MC, SK-N-SH, and IMR-32 cells were 32,56, 23, 36, and 26 hr, respectively. Cells of all lines formed colonies in soft agar, and, after variable latency periods, LA-N-1, LA-N-2, SK-N-MC, and IMR-32 cells formed tumors in athymic nude mice. The marker chromosome(s) characteristic of each cell line was present in more than 90% of cells of given line. Significant plasminogen-dependent fibrinolytic activity was present in cells of all lines. These studies indicate that LA-N-1 and LA-N-2 cells arose from single but different aberrant progenitor cells and that they have properties of neuroblastoma cells. They also demonstrate that cell lines derived from human neuroblastomas are heterogenous as are the tumors in children.

Chromosomal instability in cell lines derived from patients with xeroderma pigmentosum

The chromosomes of four cell lines derived from skin biopsies of four patients with xeroderma pigmentosum (XP) were studied and compared with corresponding controls. In the early passages, all XP lines had normal chromosome constitution with rates of polyploidy and chromosome aberrations within the range found in the controls. In the later passages, the XP cell lines had higher levels of chromosome abnormalities. The degree of abnormalities varied greatly among the XP lines; two lines had very high level of polyploidy (up to 50%) and cells with chromosome aberrations (up to 79%), the other two XP lines had a normal level of polyploidy and a slightly higher incidence of cells with chromosome aberrations than normal. The most common type of aberration was dicentrics.

Automated method for exchange transfusion

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Endothelial cell loss after small incision cataract surgery

DOI: http://dx.doi.org/10.3126/nepjoph.v3i2.5273Nepal J Ophthalmol 2011; 3(2): 177-180