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Oncogenesis and Metastasis
Published in Karl H. Pang, Nadir I. Osman, James W.F. Catto, Christopher R. Chapple, Basic Urological Sciences, 2021
Cells not actively dividing are held in cellular quiescence in G0 phase.This occurs in response to the lack of nutrition/growth signals.
Fibrogenic Cytokines in Airway Fibrosis
Published in Alastair G. Stewart, AIRWAY WALL REMODELLING in ASTHMA, 2020
Current theories of cell division propose that at least two different classes of signal are required for fibroblast mitosis to occur.35 These signals are (1) competence factors, which induce cells in G0 phase of the cell cycle to enter G1 and (2) progression factors, which stimulate competence-primed cells to complete G1 and progress to the S phase of the cell cycle. The important competence factors for fibroblasts include platelet-derived growth factor (PDGF), fibroblast growth factor (FGF), and fibronectin. Insulin-like growth factor (IGF) and transforming growth factor-β (TGFβ) are known to be progression factors for fibroblasts. These growth factors will be discussed in the following section.
Tumour growth and response to radiation
Published in Michael C. Joiner, Albert J. van der Kogel, Basic Clinical Radiobiology, 2018
The net growth rate, or the VDT, of tumours results from the balance of cell production and cell loss. Cell production is determined by the proportion of cells in the compartment of actively dividing cells (growth fraction [GF]) and the time required to complete the cell cycle (cell-cycle time, TC). Cells from the GF compartment move through the cell cycle and are distinguished from cells outside the cell cycle. Cells outside the cell cycle (in G0 phase) may enter the cell cycle (recruitment of temporarily resting cells) or remain permanently in the G0 phase (sterile or differentiated cells). Taking these parameters together, tumours grow fast if the GF is high, the cell-cycle time is short or the cell loss is low.
Clinical efficacy and mechanism for focused ultrasound (FUS) in the management of cervical intraepithelial neoplasia 1 (CIN1)
Published in International Journal of Hyperthermia, 2020
Zhenhua Fu, Yijin Fan, Can Wu, Ping Yan, Yibi Ye, Huan Yang, Chengzhi Li
Ki-67, also known as a cell proliferation index, is a nuclear antigen expressed in proliferating cells. It is synthesized in the G1, S, G2 and M phases of cell proliferation cycle. It was not expressed in G0 phase and its half-life is short, which could accurately reflect the activity of cell proliferation. Bean confirmed [22] that the positive rate of Ki-67 expression increased gradually in cervical inflammatory disease, CIN and cervical cancer; therefore, it could be used as a potential biomarker for cervical biopsy to identify the precancerous epithelial lesions. Researchers reported [23–25] that there was a positive correlation and high consistency between the expression of p16 and Ki-67 in cervical tissues. Their expressions are similar in benign cervical lesions, CIN, cancer and glandular epithelial lesions; however, the expressions of p16 and Ki-67 are significantly enhanced with the increase of the grade of CIN. By combined testing, the sensitivity and specificity of the diagnosis of CIN lesions are both improved. The results of our study showed the expression of p16 and Ki-67 both decreased in cervical tissues of LSIL patients in 3 months after focused ultrasound treatment, which is consistent with the results of previous reported studies [23,24].
The biological effects of electromagnetic exposure on immune cells and potential mechanisms
Published in Electromagnetic Biology and Medicine, 2022
Chuanfu Yao, Li Zhao, Ruiyun Peng
The cell cycle refers to the time elapsed from the end of cell division to the end of the next cell division, including the interphase and split phase (M phase). And the interval could be divided into three phases, the early stage of DNA synthesis (G1 phase), the DNA synthesis stage (S phase) and the late stage of DNA synthesis (G2 phase). Moreover, cells might temporarily leave the cell cycle and stop cell division to perform a certain biological function after a cycle of division, which named G0 phase. Apoptosis, an active cell death caused by various internal and external factors triggering cellular death program, plays pivotal roles in maintaining internal environmental homeostasis via removing excess, useless and harmful cells.
Early stage T1-weighted perfusion magnetic resonance imaging: a factor that predicts local control response in patients with meningioma who underwent gamma-knife radiosurgery
Published in Neurological Research, 2022
Anas Abdallah, Mehmet Hakan Seyithanoğlu, Meliha Gündağ Papaker, Ayşe Aralaşmak, Selçuk Yapar, Gökhan Baloğlu
GKRS does not eliminate the tumor but diminishes the division ability of the tumor cells by keeping them at the G0 phase. After radiotherapy, fibrosis and necrosis develop in the tumor, and this eventually decreases the size and volume of the meningioma [12,14]. The optimal treatment dose ranges between 12 and 15 Gy for meningiomas. Higher doses increase the complication risk without increasing the tumor control rate, while doses lower than 12 Gy increase the recurrence risk of meningioma. To avoid GKRS-related complications, the dose received should not exceed 8 Gy for the optic nerve and 14 Gy for the brain stem [4,13–15].