Biomedical subjects

S Fedoroff

Publications and source records attributed to S Fedoroff.

At least 73 records · Page 4Linked to original sources

PubMed1979

Effect of horse serum on neural cell differentiation in tissue culture.

The effects of various concentrations of horse serum on dissociated mouse glial precursor cells in colony cultures were evaluated. High concentrations (20% or more) favored cell attachment but inhibited cell proliferation and differentiation, whereas lower concentrations (5% to 10%) favored cell proliferation and differentiation. In fetal bovine serum the cells did not attach to culture surfaces to the same degree nor did they achieve the same level of differentiation as in corresponding concentrations of horse serum.

Animals↗

PubMed1978

Kinetic characteristics of the glutamate uptake into normal astrocytes in cultures.

Kinetics for uptake and release of glutamate were measured in normal, i.e., nontransformed, astrocytes in cultures obtained from the dissociated, cortex-enriched superficial parts of the brain hemispheres of newborn DBA mice. The uptake kinetics indicated a minor, unsaturable component together with an intense uptake following Michaelis-Menten kinetics. The Km (50 micrometer) was reasonably comparable to the corresponding values in brain slices and in other glial preparations. The Vmax (58.8 nmol min-1 mg-1 protein) was, however, much higher than that observed in glial cell lines or peripheral satellite cells, and also considerably higher than that generally reported for brain slices. The release of glutamate was much smaller than the uptake, and only little affected by an increase of the external glutamate concentration, suggesting a net accumulation of glutamate rather than a homoexchange. Such an intense accumulation of glutamate into normal astrocytes may play a major role in brain metabolism and may help keep the extracellular glutamate concentration below excitatory levels.

Animals↗

PubMed1978

The development of chick spinal cord in tissue culture. II. Cultures of whole chick embryos.

By using whole-chick-embryo cultures followed by fragment cultures of spinal-cord primordia, it was possible to reproduce in vitro the whole process of neuronal development beginning with its initiation and continuing up to and including the maturation of neurons. Normal whole embryos were developed to Hamilton-Hamburger stages 17 and 18 by growing embryos from the primitive streak stage on large (28-mm) glass rings. The advantage of whole-embryo cultures is that development can be staged accurately, which is especially important during the early stages when morphogenesis progresses very rapidly. By using such accurately staged embryos and tritiated thymidine, we have determined that some postmitotic neuronal precursor cells appear in chick embryos as early as Hamburger-Hamilton stages 4 and 5, i.e. the definitive streak stages before the neural tube has formed.

Animals↗

PubMed1978

An audiovisual program in cell biology.

Cell biology has been divided into 19 topics for the purpose of planning audiovisual materials. One of these topics, the structure and function of cell membranes, has been developed as a series of seven self-instructional slide-tape units and tested in five medical schools. Organization of advisers, analysis and definition of objectives and content, and development and evaluation of scripts and storyboards are discussed.

Audiovisual Aids↗

PubMed1977

The development of chick spinal cord in tissue culture. I. Fragment cultures from embryos of various developmental stages.

Explants from neural tube and spinal cord of chick embryos at developmental stages 8 through 36 were cultured on collagen-coated cover glasses for 21 days. The cultures of neural tube at stages 10 to 14 contained many neuronal precursor cells which gave rise to mature neurons. This was verified by cumulative labeling of cultures with tritiated thymidine. Explants from spinal cords of stages 26 and 27 contained fewer precursor cells, and at stage 36, only 7% of mature neurons were labeled. Regardless of the stage of development at which explants were made (stages 8 through 36), all cultures had a similar appearance after 21 days, indicating that cells from explants taken from earlier developmental stages (before neurons were formed) "caught up" with the explants from later developmental stages, which already had formed neurons at the time of explantation.

Animals↗

PubMed1977

Effects of culture milieus on the development of mouse blastocysts in vitro.

Various culture milieus were examined for their support of mouse blastocyst development. Two important variables were the time at which human cord serum was added to the medium and the concentration of amino acids. In the best medium. Eagle's Minimum Essential Medium (fortified with six times the usual amino-acid concentration plus 20 percent fetal bovine serum, replaced after 48 hr with human cord serum), 83 percent of the blastocysts shed the zona pellucida, 58 percent developed to the early egg cylinder stage, 42 percent to the advanced egg cylinder stage and 22 percent attained the primitive streak stage after 6 to 8 days of culture.

Amino Acids↗

PubMed1975

The effect of normal spleen cells on 3H-thymidine uptake by target cells in vitro.

When tumour cells (line L cells) were grown in culture with syngeneic normal non-immune C3H/He mouse spleen cells or in the cell free supernatant of these spleen cells they incorporated less tritiated thymidine (3H-Tdr) than when grown by themselves. Despite this effect there was no depression in either cell growth or DNA synthesis. Autoradiographic studies revealed that the decrease of 3H-Tdr incorporation into tumour cells in the presence of spleen cells was not due to inhibition of cell entry into S phase but due to the amount of 3H-Tdr the tumour cells incorporated. Since the medium of spleen cell cultures was found to contain DNA and the addition of calf thymus DNA to fresh growth medium also resulted in decreased 3H-Tdr uptake by the tumour cells, it was concluded that line L cells utilize DNA released by spleen cells into the medium for de novo DNA synthesis. On the basis of these findings, it is suggested that caution be used in interpreting decreased 3H-Tdr uptake as determined by scintillation counting as evidence for a cytostatic effect exerted by lymphoid cells or their supernatants in vitro.

Animals↗

PubMed1974