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J HOFFMAN

Publications and source records attributed to J HOFFMAN.

At least 19 recordsLinked to original sources
PubMed1964

THE REPLICATION TIME AND PATTERN OF CARCINOGEN--INDUCED HEPATOMA CELLS.

The replication time and pattern have been investigated in hepatoma cells induced by feeding 3'Me-DAB to male rats for 5 months. With the use of tritiated thymidine as a DNA label along with autoradiography, mitotic nuclear labeling has been studied 0.5 to 72 hours after the administration of the label. The following time intervals have been estimated: replication time, 31 hours; DNA synthesis, 17 hours; G(2) plus Mitosis, 2 hours; G(1), 12 hours. Only about 8 per cent of the tumor cell (interphase) population is "flash" labeled, following a single dose of 50 microC of H(3)TDR. This group of cells has been followed through three cycles of division. The repeated rhythmic passage of tumor cells through cell division is similar to that previously reported for normal liver cells in the growing rat. However, tumor cells have longer replication and DNA synthesis times. In addition, the several time intervals studied vary more in the tumor cell population than they do in the growing normal cell population.

Autoradiography↗
PubMed1963

The replication time and pattern of the liver cell in the growing rat.

Three-week-old male rats of the Wistar strain were given tritiated thymidine, 1 microc/gm body weight, intraperitoneally and were killed at intervals from 0.25 to 72 hours later. Autoradiographs were made from 5 micro sections, stained by the Feulgen method. The replication time and its component intervals were determined from the scoring of the labeling of interphase nuclei as well as of prophase, metaphase, anaphase, and telophase nuclei. Absorption of the intraperitoneally injected label is rapid and is attended by "flash" labeling during interphase. The results show that at any one time about 4 per cent of the liver cells are synthesizing DNA preliminary to cell division. These cells alternate with waves of other cells and it is estimated that about 10 per cent of the liver cell population is engaged in cell duplication. The replication time is about 21.5 hours, and its component intervals occupy the following times: DNA synthesis, 9 hours; post-DNA synthesis gap, 0.50 hour; prophase, 1.3 hours; metaphase, 1.0 hour; anaphase, 0.4 hour; telophase, 0.3 hour; postmitosis gap, 9.0 hours. A group of liver cells has been recorded in at least 3 successive replication cycles.

Anaphase↗