Studies on the nature of replicating DNA of HeLa cells.
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Alkalies↗
Biomedical subjects
D L Friedman
Publications and source records attributed to D L Friedman.
A nuclear system for DNA replication from synchronized HeLa cells.
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Adenosine Triphosphate↗
Correlation of the percent of positive Chlamydia trachomatis direct fluorescent antibody detection tests with the adequacy of specimen collection.
Chlamydia trachomatis is an obligate, intracellular parasite infecting the columnar and transitional cells lining the endocervix, uterus, fallopian tubes, rectum, urethra, and epididymis. We determined if the percent of specimens positive for C. trachomatis in the Microtrak Direct Specimen Test depended on the quality of specimens obtained. Female genital slides (649) were evaluated by the direct fluorescent antibody (DFA) test for the presence and numbers of (a) C. trachomatis elementary bodies and (b) columnar, transitional and squamous epithelial cells, and polymorphonuclear neutrophils (PMNs). Only 138 (21.3%) of the 649 slides were considered to be adequately taken, that is, containing columnar/transitional cells either alone or in conjunction with squamous cells and/or PMNs. Of the 138 adequate slides, 10 (7.2%) were C. trachomatis positive. However, 511 (78.7%) of the 649 slides were judged inadequate; 395 contained only squamous cells and/or PMNs, 19 were too thick to determine cell types, 46 contained only cell debris, and 51 contained neither cells nor debris. Only four (0.78%) of 511 were C. trachomatis positive. Thus adequate specimens containing columnar/transitional cells for C. trachomatis detection had a tenfold increase in the percent of positive results compared to inadequately collected specimens. By using the DFA test, one has the advantage of determining the adequacy of the specimens obtained as well as the presence of chlamydiae.
Adolescent↗
Inhibition of G2 phase in unsynchronized HELA cells: synergism between adenosine 3':5'-monophosphate analogues and phosphodiesterase inhibitors.
The involvement of cyclic nucleotides of G2 phase of the cell cycle was reexamined in unsynchronized HeLa cells. Two methods were employed to determine if cell cycle traverse was affected by chemical agents. The first method analyzed cell density changes a relatively early times after drug treatment. The second method entailed selection of a cohort of "tagged" G2 cells and analysis of the progress of these cells into mitosis. Synergism between the effects of low levels of cyclic nucleotide analogues and phosphodiesterase inhibitors was used as a criterion for the specificity of an agent's action. Using both methods of cell cycle analysis, synergistic inhibition of cell division was observed with adenosine 3':5'-monophosphate analogues. No synergism was observed with various control compounds or with guanosine 3':5'-monophosphate analogues. The results are interpreted to indicate that adenosine 3':5'-monophosphate exerts an inhibitory action in G2 phase of the cell cycle.
3',5'-Cyclic-AMP Phosphodiesterases↗