Search results
Results from the WOW.Com Content Network
Cells are least sensitive when in the S phase, then the G 1 phase, then the G 2 phase, and most sensitive in the M phase of the cell cycle. This is described by the 'law of Bergonié and Tribondeau', formulated in 1906: X-rays are more effective on cells which have a greater reproductive activity. [1] [2]
The eukaryotic cell cycle consists of four distinct phases: G 1 phase, S phase (synthesis), G 2 phase (collectively known as interphase) and M phase (mitosis and cytokinesis). M phase is itself composed of two tightly coupled processes: mitosis, in which the cell's nucleus divides, and cytokinesis, in which the cell's cytoplasm and cell membrane divides forming two daughter cells.
One of the major limitations of radiotherapy is that the cells of solid tumors become deficient in oxygen. Solid tumors can outgrow their blood supply, causing a low-oxygen state known as hypoxia . Oxygen is a potent radiosensitizer, increasing the effectiveness of a given dose of radiation by forming DNA-damaging free radicals.
During cell division, demecolcine inhibits mitosis at metaphase by inhibiting spindle formation. Medically, demecolcine has been used to improve the results of cancer radiotherapy by synchronising tumour cells at metaphase, the radiosensitive stage of the cell cycle.
Highly radiosensitive cancer cells are rapidly killed by modest doses of radiation. These include leukemias, most lymphomas, and germ cell tumors. The majority of epithelial cancers are only moderately radiosensitive, and require a significantly higher dose of radiation (60–70 Gy) to achieve a radical cure. Some types of cancer are notably ...
Get breaking news and the latest headlines on business, entertainment, politics, world news, tech, sports, videos and much more from AOL
This figure illustrates the typical change in the relative radiosensitivity for a biological effect such as cell death when exposed to radiations of low ionizing density (e.g. x-rays). The hyperbolic relationship shown has a maximum OER of 2.70 for 100% oxygen (at 760 mmHg), with a half-range OER value at 4.2 mmHg or 0.55% of oxygen.
What addicts face is a revolving door, an ongoing cycle of waiting for treatment, getting treatment, dropping out, relapsing and then waiting and returning for more. Like so many others, Tabatha Roland, the 24-year-old addict from Burlington, wanted to get sober but felt she had hit a wall with treatment. “I hate my life so much..