Document Detail

Cell cycle progression in human cells following re-oxygenation after extreme hypoxia: consequences concerning initiation of DNA synthesis.
MedLine Citation:
PMID:  8439587     Owner:  NLM     Status:  MEDLINE    
The initiation of DNA synthesis and further cell cycle progression in cells during and following exposure to extremely hypoxic conditions in either G1 or G2 + M has been studied in human NHIK 3025 cells. Populations of cells, synchronized by mitotic selection, were rendered extremely hypoxic (< 4 p.p.m. O2) for up to 24 h. Cell cycle progression was studied from flow cytometric DNA recordings. No accumulation of DNA was found to take place during extreme hypoxia. Cells initially in G1 at the onset of treatment did not enter S during up to 24 h exposure to extreme hypoxia, but started DNA synthesis in a highly synchronous manner within 1.5 to 2.25 h after reoxygenation. The duration of S phase was only slightly affected (increased by approximately 10%) by the hypoxic treatment. This suggests that the DNA synthesizing machinery either remains intact during hypoxia or is rapidly restored after reoxygenation. Cells initially in G2 at the onset of hypoxia were able to complete mitosis, but further cell cycle progression was blocked in the subsequent G1. Following reoxygenation, these cells progressed into S phase, but the initiation of DNA synthesis was delayed for a period corresponding to at least the duration of normal G1 and did not appear in a synchronous manner. In fact, cell cycle variability was found to be increased rather than decreased as a result of exposure to hypoxia starting in G2. We interpret these findings as an indication that important steps in the preparation for initiation of DNA synthesis take place before mitosis. Furthermore, the change in cell cycle duration induced by hypoxia commencing in G1 is of a nature other than that induced by hypoxia commencing in other parts of the cell cycle.
O Amellem; E O Pettersen
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Cell proliferation     Volume:  26     ISSN:  0960-7722     ISO Abbreviation:  Cell Prolif.     Publication Date:  1993 Jan 
Date Detail:
Created Date:  1993-03-31     Completed Date:  1993-03-31     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  9105195     Medline TA:  Cell Prolif     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  25-35     Citation Subset:  IM    
Department of Tissue Culture, Norwegian Radium Hospital, Oslo.
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MeSH Terms
Cell Cycle / drug effects*
Cell Hypoxia
Cell Line
Cell Separation
DNA / biosynthesis*
Flow Cytometry
G1 Phase / drug effects*
Oxygen / pharmacology*
Reg. No./Substance:
7782-44-7/Oxygen; 9007-49-2/DNA

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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