The antimitotic action of an aromatic nitrogen mustard on tissue cultures

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Observations with the electron microscope on cells of the chick chorio-allantoic membrane infected with influenza virus

Preparations of influenza-infected chick chorio-allantoic membrane made by two types of tissue culture and by sectioning, have been studied in the electron microscope. Comparisons have been made of influenza A' (FM1), influenza A (PR8), and swine influenza (V15), three strains which produce different relative numbers of filaments. Normal surface projections which may be confused with influenza filaments are described. Extruded products of degenerating cells, usually bleb-shaped, may also be found both in uninfected allantoic fluid and tissue cultures. It appears that the filaments and spheres of influenza virus, concurrently projecting from the free cell surface, represent the only visible change in the cells until late in the infection,—how late the present work does not tell. No definite evidence of a generalized infection throughout the cytoplasm or of inclusions was found. Additional evidence is presented for the assumption that the filaments have a significant role in the final development of the free virus.

Growth of the Lansing strain in human embryonic tissues

This paper presents observations on the growth of Lansing poliomyelitis virus in fluid cultures of various human embryonic and adult tissues. The evidence suggests that viral multiplication has occurred in cultures of monkey testis, human embryonic kidney, and mixtures of brain and cord. Satisfactory virus growth has been obtained particularly in cultures containing human embryonic brain and cord. Virus is present in tissue culture fluids in which the original inoculum has been diluted 10−33.3 by subcultivation. Preliminary observations suggest that a synthetic medium (Mixture 199) devised by Morgan, Morton, and Parker is superior to Hanks–Simms solution as a nutritive medium in such cultures. The cytopathogenic effect of the virus, as revealed by pH determinations and cell morphology, has been noted, although a characteristic pH differential between virus infected and control flasks was not commonly observed. Attempts to grow the virus on a larger scale in Kolle flasks are described.

The specific amino acid requirements of a human carcinoma cell (Stain HeLa) in tissue culture

The amino acid requirements of a human uterine carcinoma cell (HeLa strain) have been defined. The 12 compounds previously found to be essential for the growth of a mouse fibroblast proved similarly essential for this human epithelial cell. They included arginine, cyst(e)ine, histidine, and tyrosine, in addition to the eight amino acids required for nitrogen balance in man (isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine). Only the L-amino acids were active; the D-enantiomorphs had no demonstrable effect at physiologic concentrations. The minimum concentrations required for survival and limited growth varied from 0.003 µM per ml. for L-tryptophan, to 0.1 µM per ml. for L-lysine. The concentrations permitting optimum growth similarly varied from 0.01 µM per ml. for tryptophan, to 0.1 µM per ml. for leucine, isoleucine, threonine, lysine, and valine. The latter optimum concentrations of the individual amino acids were closely correlated with their serum levels. With at least six of the amino acids, high concentrations, in the range 1 to 10 µM per ml., caused a definite growth inhibition. In the absence of a single essential amino acid, degenerative changes occurred in the cells, culminating in their death and dissolution. In the early stages, however, these degenerative changes could be reversed by the restoration of the missing component.

Pseudoneoplastic nonspecific proliferative lesions on the chorio-allantois of the chick embryo

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The effect of poliomyelitis virus on human brain cells in tissue culture

Poliomyelitis virus I, Mahoney strain, affected human brain cells grown in tissue cultures usually causing death of the cells in 3 days. The neurons reacted in different ways to the virus, some died with their neurites extended, others contracted one or more of their neurites. Terminal bulbs were frequently formed at the tips of the neurites when they were being drawn into the cell body. The final contraction of the cell body and the change into a mass of granules were often very sudden. Vacuoles often developed in the neuron. There was no recovery. Astrocytes, oligodendroglia, and macrophages were affected by the virus but not as quickly as the neurons. The age of the tissue culture was not a factor when the cells were in good condition. The age of the individual donor of the brain tissue was a factor; the fetal brain cells appeared to be more sensitive to the virus than the adult brain cells. The fetal neurons often reacted ½ hour after inoculation while the adult neurons reacted more slowly, 2 to 24 hours after inoculation. All these changes seemed to be caused by virus infection because they were prevented by specific antiserum or by preheating the virus.

Antagonistic effects of 6-mercaptopurine and coenzyme A on mitochondria and mitosis in tissue culture

The partial mitotic inhibition caused by 6-mercaptopurine in tissue cultures of Crocker mouse sarcoma 180 and embryonic mouse skin is blocked by co-enzyme A. 6-Mercaptopurine and coenzyme A also have opposite effects on mitochondrial morphology. Mitochondria in cells treated with 6-mercaptopurine become thin and fragmented. Coenzyme A blocks this effect, and alone coenzyme A makes for longer and thicker mitochondria. 6-Mercaptopurine inhibits lipogenesis in embryo skin fibroblasts, and this inhibition is partly counteracted by coenzyme A, which by itself makes for a greater accumulation of lipid droplets in the cytoplasm. It is suggested that at least one part of the action by which 6-mercaptopurine decreases mitotic incidence in tissue cultures may be an interference on the part of 6-mercaptopurine, acting as an antimetabolite of coenzyme A, in mitochondrial function related to cell division.

The mammalian cell-virus relationship. IV. Infection of naturally insusceptible cells with enterovirus ribonucleic acid

Ribonucleic acid extracted with phenol from Type 1 poliovirus, Coxsackie A-9, Coxsackie B-1, and ECHO 8 viruses infected non-primate cells and animals insusceptible to whole virus as such. Viral RNA was proved infectious for insusceptible cells in test systems of established cell lines, primary monolayer cultures, Maitland type cultures, and living animals inoculated intracerebrally. Cells of rabbit, swine, mouse, guinea pig, chicken, and hamster were infected. Each virus produced was identical with the virus donating RNA, in (a) neutralization by homotypic antiserum, (b) resistance to ribonuclease treatment, and (c) failure to be adsorbed or replicated by nonprimate cells, even of the strain producing the virus from RNA. Produced virus was adsorbed and replicated by susceptible primate cells as usual. Virus in RNA-infected cell cultures was produced in a single cycle unaccompanied by overt cytopathic effect on non-primate cells or disease of intracerebrally inoculated animals. By drastic elution of infective poliovirus associated with rabbit cells exposed to massive inocula of intact virus, intact poliovirus was shown to infect insusceptible non-primate cells to produce progeny indistinguishable from the parent virus population. Under these conditions, infection was accomplished by about 10 virus plaque-forming units per billion inoculated.

The role of carbon dioxide as an essential nutrient for six permanent strains of fibroblasts

The results of these studies demonstrate that carbon dioxide is required for the growth and maintenance of strains of fibroblasts derived from human tissues, strains FS4-705 and U12-705, from mouse tissue, strain L-705, and from rabbit tissues, strains RM3-56, RS1-56, and RT-56 in a chemically defined medium containing phosphite buffer in place of bicarbonate and supplemented with dialyzed serum and dialyzed embryo extract. Under these conditions, the cells fail to proliferate at a significant rate and begin to degenerate within 5 to 10 days when the flasks are not stoppered. Sufficient carbon dioxide is produced by the cells to promote growth as indicated by the fact that maximal proliferation is obtained in the same phosphite media when stoppered flasks are employed. With the exception of RS1-56, all the remaining strains tested can be propagated serially in open flasks containing phosphite medium prepared with whole serum and embryo extract. The rate of growth under these conditions, however, is only one-half to one-third that obtained in stoppered flasks containing phosphite medium or the conventional bicarbonate medium.

Chromosomal constitution of cells in tissue culture

A convenient, reliable method for chromosome delineation of animal cells grown as monolayers on glass has been applied to human, opossum, and Chinese hamster cells. Tissue cultured cells from 5 different, normal organs of 7 different human subjects uniformly displayed the expected chromosome number of 46 and showed no variations in morphology or number other than the expected sex differences and a small incidence of polyploidy. The chromosomes of normal cells from the American opossum were as uniform as those of human cells. Cells of the inbred Chinese hamster demonstrated appreciable karyotype variability, the cause of which is under investigation. The chromosome number and morphology of cells from normal human tissues have remained constant after more than 5 months of continuous, rapid growth in tissue culture involving scores of vessel transfers and a number of generations equivalent to many billions of progeny. By the use of routine recloning, even cells of malignant, aneuploid constitution have been maintained in active growth for 3 years and hundreds of generations, with stable chromosomal and metabolic characteristics. The cells of the American opossum and Chinese hamster which possess only 22 chromosomes have been established in vitro and are especially suitable for genetic studies. The readily recognizeable Y and X chromosomes of the male opossum are particularly favorable as cytological markers. Photomicrographs of the chromosomes of the various cells employed are presented.

Molecular growth requirements of single mammalian cells. III. Quantitative colonial growth of single S3 cells in a medium containing synthetic small molecular constituents and two purified protein fractions

Two purified serum protein fractions, fetuin and serum albumin, will replace whole or dialyzed serum in supporting the growth of single S3 HeLa cells in an otherwise chemically defined nutrient solution. In the serum-free medium, single S3 cells will form macroscopic colonies with essentially 100 per cent efficiency. The generation time of S3 cells in the serum-free medium is approximately 50 per cent greater than that observed in an optimal, serum-containing medium. All components of the serum-free medium are available commercially, except fetuin, which can easily be prepared in substantial quantities. The problem of the purity of the protein preparations and of their possible roles in promoting cell growth is discussed.

Genetics of somatic mammalian cells. III. Long-term cultivation of euploid cells from human and animal subjects

A methodology designed to eliminate mitotic inhibitor action and involving use of pretested fetal calf serum and careful pH and temperature control has been described by which cells from normal human and animal tissue can be maintained in active growth for long periods in vitro without development of aneuploidy. By means of this procedure, it is possible reliably to establish cell cultures from minute skin biopsies which can be taken from any individual. Clones of mammalian cells with chromosomal markers have been isolated by this means from x-irradiated non-irradiated cell cultures. Application of these techniques to chromosome delineation in large numbers of human subjects; determination of chromosomal sex in patients; spontaneuos and induced genetic changes in somatic mammalian cells in vivo and in vitro; comparison of metabolic differences between normal and cancerous cells and other problems have been indicated.