Thymidine, labeled

Verhoef, J., Petersen, P. K and Quie, P. G. (1977) Kinetics of staphylococcal opsonization, attachment, ingestion and killing by human polymorphonuclear leukocytes a quantitative assay using [ H]thymidine labeled bacteria. J. Immunol. Methods 14, 303-311. 

The mitotic index is the fraction or percentage of cells in mitosis within a given cell population. The thymidine labeling index is the fraction of cells incorporating radioactive thymidine. They represent cells in M-phase and S-phase and define the proliferative characteristics of normal and tumor cells. 

These can be used on cellular DNA isolated, for example, from cells previously exposed to oxidant or other stress. Methods in major use involve using tritiated thymidine labelling or fluorescence tags. The former method is described here. 

The results of incorporation experiments using tritiated thymidine lend support to the hypothesis that thymidine rhamnosyl pyrophosphate in Lactobacillus acidophilus is an intermediate on the pathway to deoxyribonucleic acid synthesis. When cells were grown in a medium containing tritiated thymidine, labeled thymidine rhamnosyl pyrophosphate constituted two-thirds of the total label in the acid-soluble fraction. When these cells were transferred to a medium containing 2-deoxyadenosine, 2-deoxy-guanosine, and 2-deoxycytidine as the nucleosides, 99 % of the label initially present was transferred to deoxyribonucleic acid after incubation for 50 minutes. Therefore, almost complete incorporation (into deoxyribonucleic acids) of the isotope from tritiated th3anidine had occurred. 

Cells are plated at the desired density, either on sterile glass cover-slips for microscopic examination, or directly into multiwell plates (prepare each point at least in tripUcate) for population analysis by ELISA. After treatment of the cells with the desired growth agents, BrdU is added, following the same criteria already discussed for thymidine labeling (short pulse, or long term). Cells are then washed free of residual BrdU by rinsing with PBS, and fixed in ethanol. Fixed cells can be stored at 4°C for further analysis. BrdU... 

Keenan, K.P., Combs, J.W. and McDowell, E.M. (1982c). Regeneration of hamster tracheal epithelium after mechanical injury III. Large and small lesions comparative stathmokinetic and single pulse and continuous thymidine labeling autoradiographic studies. Virchows Arch. 41, 231-252. 

Batigelli et al. [139] explored the possibility of using the synthesis rate of tritiated thymidine-labelled DNA as a measure of cellular reaction to injury. However, the technique would appear to offer little advantage over other methods as results indicate that the response is coincident with histological abnormalities. 

Rats Wistar M B-6-deficient diet + DL-Trp (1.4%) 1 t [3H] thymidine labeling of epithelium ... 

Ultimately, the major effect of all promoters, regardless of type, is the expansion of the initiated cell to form visible tumors. Table III lists possible mechanisms for the selection of initiated epidermal cells by tumor promoters. Of the four mechanisms mentioned, evidence supporting each can be found experimentally. Recent studies by Morris (.34) have demonstrated that slowly cycling basal cells (thymidine label retaining cells) are induced to divide by a... 

Radioactive Compounds. a) Thymidine, labelled in position 2 with or in position 6 with (New England Nuclear,... 

Isopycnic gradients of bromodeoxyuridine plus [ H]-thymidine-labeled DNA from cells exposed to MMS separated the DNA into heavy semiconservatively replicated DNA and normal density repair replicated DNA. The amount of repair in WIL-2 cells exposed to MMS was strongly dependent on both MMS dose and SAB concentration (Fig. 3a,b). At low concentrations of SAB there was a sharp increase in repair replication which saturated at 2 mM (Fig. 3b). 

Fig. 2. Dimethyl sulfate causes DNA single-strand breaks in Friend cells that are potentiated by SAB. [ Cl-thymidine labeled Friend cells, treated with 50 yM dimethyl sulfate for 30 min, were centrifuged and resuspended in fresh media with or without SAB. Samples were removed at 0, S and 7 h after treatment and analyzed by alkaline elution. Numbers refer to h and + to presence of SAB...

Najarian, j. S., and J. D. Feldman Passive transfer of tuberculin sensitivity by tritiated thymidine-labeled lymphoid cells. J. exp. Med. 114, 779—790 (1961). 

Passive transfer of contact sensitivitv by tritiated thymidine-labeled lymphoid cells. 

Crocidolite (UICC reference sample) Rat lung mesothelial cells H-Thymidine labelled cells Mesothelial cells showed increased DNA synthesis at 1 week. Adamson et al. (1997) ... 

Peritoneal macrophages were parasitized with H-thymidine-labeled Leishmania enriettii promastigotes, followed by activation with EP-AG. The macrophages were lysed and the number of released viable parasites was quantified [7] (Tab. 4). 

Other examples of the cytological effects of surfactants have been reported in papers dealing with cell proliferation. Tween 60 brings about a rapid and sustained intensification of cell proliferation following application as a 10% solution to the epidermis [193] there is rapid and sustained epidermal thickening accompanied by an increase in the thymidine-labelling index. Three surfactants have been studied as modulators of transformed cell proliferation [194]. Some surface active compounds have both in vitro and in vivo antitumour activity, and others inhibit the development of tumour metastases in vivo. Lack of in vivo effect... 

The adsorption and penetration of AAV containing H-thymidine-labeled DNA has been measured with KB cells in spinner culture (Rose and Koczox, 1972 Berns and Adler, unpublished data). Adsorption reached a maximum and plateaued one to two hours after infection. Approximately 16-30% of the added viral label was irreversibly associated with the cells by this time. Depending on the method of cell fractionation, 25-45% of the bound radioactivity was eventually (by 20 hours) found in the nuclear fraction, the majority within two hours. Uncoating, as measured by sensitivity of the labeled DNA to DNase, took place in the nucleus. Maximum uncoating occurred by I6 hours post infection and represented approximately 85% of the total DNA (Berns and Adler, unpublished data). 

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