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Biomedical subjects

H J Saxholm

Publications and source records attributed to H J Saxholm.

12 recordsLinked to original sources
PubMed1987

A new in vitro assay for cell motility and proliferation.

We have described and characterized a new micropore membrane assay for migration and proliferation of cells of various tumourigenic potential. The assay was developed to facilitate analysis of some aspects of cancer invasion and metastasis. Tumorigenic and non-tumorigenic C3H/10 T 1/2 cells grow in and migrate out of a culture chamber during a 1-11 day period, the shorter periods are used for chambers with 6 micron thick polycarbonate membranes, the longer ones for 140 micron thick cellulose nitrate membranes. Cell growth within the chambers, in their micropore membranes and on the outside of the membranes, was assessed with microscopy, electronic cell counting, flow cytometry of propidium iodide (PI) stained cells, and 3H-thymidine [( 3H]TdR) incorporation. A complete retrieval of intact cells that have traversed the membraneous chamber wall is possible, and these cells can be recultured or used in other studies. The tumorigenic cells had a steeper growth curve in vitro than the non transformed cells, but the relative sizes of the emigrated subpopulations were not significantly different. The subpopulation of tumorigenic cells that emigrated spontaneously from the chambers was less able than the subpopulation retained to populate secondary chamber cultures, suggesting that the clonogenic (stem) tumour cells are 'slow movers'.

Animals↗
PubMed1981

Studies on mutagenic and carcinogenic N-substituted aryl compounds: cosmetics and drugs.

We aimed our studies toward gaining an understanding of some of the reactions and pathways involved in the metabolism and activation of the aromatic diamines used in hair dyes and of phenacetin used in analgesic mixtures. Comparison of the data obtained from human and animal tissues established that animal tissues can serve as suitable models for evaluation of the activity of these compounds in humans.

Adult↗
PubMed1981

Oncogenic transformation and cell lysis in C3H/10T 1/2 cells and increased sister chromatid exchange in human lymphocytes by nickel subsulfide.

We have scored frequency of transformation and appearance of the oncogenic marker "long microvilli" in mouse embryo fibroblast C3H/10T 1/2 cells in culture for the compound Ni3S2. Furthermore, we have scored for Ni3S2-induced sister chromatid exchange in cultured human lymphocytes. Nickel subsulfide in moderate doses caused morphological transformation to type I, II, and III foci and induced long microvilli on the cells in the transformed cultures, demonstrating oncogenic transforming ability. Higher doses led to cell lysis after a lag period. The carcinogenic potency of Ni3S2 in this system was not as strong as that of methylcholanthrene. Ni3S2 increased the sister chromatid exchange frequency in human lymphocytes in a marginal, not dose-dependent way. The increased sister chromatid exchange may indicate that the carcinogenic effect of Ni3S2 is genetic rather than epigenetic.

Animals↗
PubMed1980

A quantitative scanning electron microscopic study of microvilli in interphase and mitosis of carcinogen-transformed fibroblasts.

SEM revealed different surface characteristics of C3H/10T 1/2 cells upon exposure to carcinogens. Long and short microvilli appeared as cytological markers in three morphologically different cell types of different oncogenic potential following exposure to DMBA. The results present evidence that our recording of microvilli in interphase cells is only negligibly influenced by microvilli-bearing mitotic cells. This report further substantiates that the evaluation of the oncogenic transformation in the C3H/10T 1/2 mouse fibroblast cell system by the estimation of cells bearing long microvilli seems to be a new promising approach utilizing SEM.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1980

Progressive loss of DNA and lowering of the chromosomal mode in chemically transformed C3H/10T1/2 cells during development of their oncogenic potential.

When mouse embryo C3H/10T1/2 fibroblasts are transformed by 7,12-dimethylbenz(a)anthracene, the development of oncogenic potential is associated with characteristic morphological changes, which can be classified into three types and which are also dependent upon the number of cell passages. This paper reports changes in DNA content studied by flow cytometry of ethidium bromide-stained nuclei and changes in chromosome number observed by counting 50 randomly chosen Colcemid-arrested metaphases of each cell culture population. The nontransformed cells maintained a stable hypotetraploid DNA content. The morphologically transformed cell showed no changes during their first passages in culture, except for the appearance of small polyploid subpopulations. The occurrence and increase of the oncogenic potential in the higher passages in the transformed cells were associated with decrease in nuclear DNA content as well as reduction in chromosome number. For the most oncogenic passages, the reduction of chromosome numbers was considerable, and there was no overlapping between the chromosome numbers of the original and the most oncogenic cells. This finding supports the view that the transformation process is a result of progression (chromosomal changes and subsequent selection) and not only of the selection of cells that were present at the start of the culture. The genetic material obviously lost in the most oncogenic cells may be different from the DNA material lost by the cells that remained nononcogenic.

Animals↗
PubMed1979

Characterization of a proteolipid complex of aminoacyl-tRNA synthetases and transfer RNA from rat liver.

A high molecular weight complex containing aminoacyl-tRNA synthetases, peptidyl acetyltransferase, lipids and tRNA has been isolated from the 250,000 x g postmitochondrial supernatant from rat liver cells. Aminoacyl-tRNA synthetase activity directed towards arginine, aspartate, glutamine, glutamate, glycine, leucine, lysine, methionine, phenylalanine, proline, serine, threonine, and tyrosine is present. An endogenous pool of aminoacyladenylates is indicated by an ATP-32PPi exchange catalyzed by the native complex, which shows a dramatic increase after addition of ATP. Lysine is the only amino acid which greatly increases the exchange rate catalyzed by the native complex in vitro, whereas components of the denatured complex activate all the 13 amino acids in the presence of ATP. Six of the eight lipid fractions were glycolipids; cholesterol and cholesterol esters were absent. The extracted RNA has many characteristics of tRNA. These findings provide evidence for the organization of aminoacyl-tRNA synthetases in a complex with peptidyl acetyltransferase that also contains lipids and tRNA and that can be readily isolated from the cytosol of rat liver cells.

Adenosine Triphosphate↗