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Biomedical subjects

D R Morrison

Publications and source records attributed to D R Morrison.

33 records · Page 2Linked to original sources
PubMed1988

Conformation-dependent recognition of a protein by T-lymphocytes: apomyoglobin-specific T-cell clone recognizes conformational changes between apomyoglobin and myoglobin.

A T-cell clone specific to apomyoglobin was generated. It was prepared from a T-cell culture obtained by in vitro driving of lymph node cells with apomyoglobin from SJL mice that have been primed in vivo with apomyoglobin. In proliferative assays, the T-cell clone responded to apomyoglobin but did not recognize native myoglobin or any of the synthetic peptides corresponding to the six T sites of myoglobin. The demonstration that a T-cell clone can be isolated, whose specificity is directed entirely to apomyoglobin and not to its counterpart myoglobin, with an identical amino acid composition, indicates the importance of the three-dimensional structure in the presentation of the protein to T cells.

Animals↗
PubMed1988

Cell bioprocessing in space: applications of analytical cytology.

Cell bioprocessing in space consists of the preparation, cultivation, purification and investigation of cells and their products in the microgravity environment of orbital space flight. Inertial acceleration is used as an independent variable to explore the limits of specific bioprocessing functions, such as cell growth and secretion, gravity-dependent phenomena in cell bioreactors, cell fusion, the influence of thermal convection on processes at cellular dimensions, the electrophoretic separation of cell subpopulations and subcellular particles, and two-phase partitioning of cells, bioparticles, and macromolecules. Analytical cytology techniques are under development for on-orbit application to future cell growth and separation experiments, such as those anticipated in the Space Station era.

Acceleration↗
PubMed1986

Electrophoretic separation and analysis of living cells from solid tissues by several methods. Human embryonic kidney cell cultures as a model.

Preparative electrophoresis of living cells has been considered for some time as a potential tool for isolating, from heterogeneous mixtures, subpopulations of cells according to function. Such a purification depends upon the retention of electrophoretic heterogeneity and the retention of function. Human embryonic kidney cells that had been in monolayer culture for 1-5 subcultivations were resuspended by treatment with trypsin and/or EDTA and suspended in a variety of electrophoresis buffers, ranging in ionic strength from 0.0015 to 0.15 M. Analytical electrophoresis with a Zeiss Cytopherometer or Pen Kem 3000 automated light-scattering electrophoretic analyzer indicated that electrophoretic heterogeneity was retained under the full range of conditions tested. Preparative electrophoresis by three methods--in a density gradient, with continuous flow, and in microgravity--indicated that electrophoretic heterogeneity coincided with functional heterogeneity; for example, some electrophoretically isolated subpopulations produced increased levels of urokinase while others produced increased level of tissue plasminogen activator.

Buffers↗
PubMed1984

Problems in the bioassay of products from cultured HEK cells: plasminogen activator.

For research and commercial purposes, the production of materials from cultured cells is progressively becoming routine. Measuring products in cell culture medium, however, is not always straight-forward even when the most appropriate product assays are utilized. A researcher interested in a particular cell product does not intend to spend time developing or refining existing assays. Instead, he would prefer using techniques and standards reported in the literature. Evaluations of enzyme activity using purified standards or control products may inadvertently lead to the assumption that the same procedures will give reproducible results when cell culture medium is assayed for the product. This report describes the selection of commercially available lots of human embryonic kidney cells and the activity of the plasminogen activator (PA) produced by these cells. PA activity was measured by the fibrin plate assay. The problems of comparing activity in conditioned culture medium with that of purified standard preparations are presented. Factors contributing to non-linearity in dose response curves, inconsistencies in activity in replicate flask cultures, and variations in repeated assays after sample storage are considered. Sample handling procedures and alternate assay systems are discussed.

Animals↗
PubMed1984

Bioprocessing in space: human cells attach to beads in microgravity.

Attachment to a substrate and survival of human embryonic kidney (HEK) cells have been tested in an incubator installed in the flight-deck of the Space Shuttle 'Challenger' during its eighth mission. HEK cells are producing the enzyme urokinase and are presently investigated as candidates for electrophoretic separation in an apparatus developed and manufactured by McDonnell Douglas. Attachment of HEK cells to a substrate is mandatory for survival and production of urokinase after electrophoretic separation. Analysis of the samples shows that cells adhere, spread and survive in microgravity (< 10(-3) x g) conditions as well as the ground controls at 1 x g. This result represents an important step towards further bioprocessing in space.

Biotechnology↗
PubMed1984

Electrophoretic separation of kidney and pituitary cells on STS-8.

A Continuous Flow Electrophoresis System (CFES) was used on Space Shuttle flight STS-8 to separate specific secretory cells from suspensions of cultured primary human embryonic kidney cells and rat pituitary cells. The objectives were to isolate the subfractions of kidney cells that produce the largest amounts of urokinase (plasminogen activator), and to isolate the subfractions of rat pituitary cells that secrete growth hormone, prolactin, and other hormones. Kidney cells were separated into more than 32 fractions in each of two electrophoretic runs. Electrophoretic mobility distributions in flight experiments were spread more than the ground controls. Multiple assay methods confirmed that all cultured kidney cell fractions produced some urokinase, and five to six fractions produced significantly more urokinase than the other fractions. Several fractions also produced tissue plasminogen activator. The pituitary cells were separated into 48 fractions in each of the two electrophoretic runs, and the amounts of growth hormone (GH) and prolactin (PRL) released into the medium for each cell fraction were determined. Cell fractions were grouped into eight mobility classes and immunocytochemically assayed for the presence of GH, PRL, ACTH, LH, TSH, and FSH. The patterns of hormone distribution indicate that the specialized cells producing GH and PRL are isolatable due to the differences in electrophoretic mobilities.

Animals↗
PubMed1984

Properties of electrophoretic fractions of human embryonic kidney cells separated on Space Shuttle flight STS-8.

Suspensions of cultured primary human embryonic kidney cells were subjected to continuous flow electrophoresis on Space Shuttle flight STS-8. The objectives of the experiments were to obtain electrophoretically separated fractions of the original cell populations and to test these fractions for the amount and kind of urokinase (a kidney plasminogen activator that is used medically for digesting blood clots), the morphologies of cells in the individual fractions, and their cellular electrophoretic mobilities after separation and subsequent proliferation. Individual fractions were successfully cultured after return from orbit, and they were found to differ substantially from one another and from the starting sample with respect to all of these properties.

Cell Line↗
PubMedDate not supplied

Presentation of antigen to T lymphocytes by non-immune B-cell hybridoma clones: evidence for specific and non-specific presentation.

Non-immune SJL (H-2s) spleen cells were fused with (H-2d) Balb/c 653-myeloma cells and the hybridomas were cloned by two limiting dilutions. The resulting hybrid B- cell clones were tested for their antigen presentation capability to SJL T-cell lines that were specific for either lysozyme or myoglobin. In proliferative assays, 53% of the antigen presenting B-cell clones were able to present both myoglobin and lysozyme (general presenters) while the other 47% presented specifically either myoglobin or lysozyme (specific presenters). The ability to selectively present either myoglobin or lysozyme indicates that antigen presentation at the clonal level can be specific or non-specific depending on the particular B-cell clone.

Animals↗