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K A Foster

Publications and source records attributed to K A Foster.

64 records · Page 4Linked to original sources
PubMed1983

Myxoviruses do not induce non-specific alterations in membrane permeability early on in infection.

The permeability characteristics of cells infected with myxoviruses have been studied by measuring the concentrative uptake of nutrients, the concentration of intracellular K+, and the maintenance of the Na+ gradient across the plasma membrane. Cells either show no change at all (Sendai virus-infected BHK cells and measles virus-infected Vero cells) or they show a decreased ability to concentrate nutrients, while intracellular K+ and the Na+ gradient remain unchanged (Sendai and influenza virus-infected L-1210 cells, measles virus-infected lymphocytes and mumps virus-infected L-41 cells). In no case, therefore, was a change observed that resembles the non-specific increase in membrane permeability induced by haemolytic paramyxoviruses (35, 42) or the non-specific membrane leakiness postulated to take place in infected cells (8, 9). A preliminary account of some of these findings has been presented (39).

Animals↗
PubMed1983

Differentiation of promyelocytic (HL-60) cells into mature granulocytes: mitochondrial-specific rhodamine 123 fluorescence.

Rhodamine 123, a fluorescent dye which binds as a result of the transmembrane potential, was used to stain the mitochondria of HL-60 cells, a cell line established from human promelocytic leukemia cells. The DMSO-induced differentiation of promyelocytic cells into mature granulocytes caused a fourfold decrease in fluorescence intensity that paralleled the disappearance of S-phase and G2M cells. This suggests that upon myeloid differentiation whereby the cells enter an irreversible quiescent state, the mitochondrial mass of the cells has decreased. This suggestion is corroborated by electron microscopy, which shows a decrease in the number of mitochondria, and by decreases in total mitochondrial protein and cytochrome oxidase activity. The respiratory rate of isolated mitochondria did not change, suggesting that the transmembrane potential remained the same. Undifferentiated cells in exponential phase of growth exhibit an intracellular heterogeneity of fluorescence intensity. This heterogeneity appears to have a cell age basis, as late S/G2M cells, obtained by centrifugal elutriation, yielded twice the fluorescence intensity of early G1 cells.

Cell Differentiation↗
PubMed1980

Survey of virally mediated permeability changes.

1. Sendai virus causes permeability changes when added to freshly isolated brain cells (cerebellum or ependymal cells) or to a culture of forebrain cells. 2. Sendai virus causes permeability changes when added to organ cultures of ferret lung or nasal turbinate. Influenza virus causes no permeability changes under these conditions. 3. Rabies virus and vesicular-stomatitis virus, in contrast with Sendai virus, do not cause permeability changes in BHK cells or Lettrée cells. 4. Serum from patients suffering from viral hepatitis does not cause permeability changes in human leucocytes; addition to Sendai virus causes permeability changes. 5. It is concluded that permeability changes accompanying viral entry occur only with certain types of paramyxovirus, but that there is little restriction on cell type. 6. MDBK cells infected with Sendai virus show permeability changes during viral release, similar to those that occur during viral entry. Because these changes do not appear to be restricted to paramyxoviruses, they may have considerable clinical significance.

Animals↗
PubMed1980

Nature of virally mediated changes in membrane permeability to small molecules.

1. The changes in membrane permeability to small molecules caused by Sendai virus [Pasternak & Micklem (1973) J. Membr. Biol. 14, 293-303] have been further characterized. The uptake of substances that are concentrated within cells is inhibited. Choline and 2-deoxyglucose, which become phosphorylated, and aminoisobutyrate and glycine, which are driven by a Na+-linked mechanism, are examples. The uptake of each compound under conditons where its diffusion across the plasma membrane is rate-limiting is stimulated by virus. Choline, 2-deoxyglucose and amino acids at high concentration, amino acids in Na+-free medium, and most substances at low temperature, are examples. It is concluded that virally mediated decrease of uptake is due to one of two causes. Substances that are accumulated by phosphorylation are not retained because of leakage of the phosphorylated metabolites out of cells. Substances that are accumulated by linkage to a Na+ gradient are no longer accumulated because of collapse of the gradient resulting from an increased permeability to Nat 2. Increased permeability to K+ and Na+ results in (a) membrane depolarization and (b) cell swelling. The latter event leads to haemolysis (for erythrocytes) and can lead to giant-cell (polykaryon) formation (for several cell types). 3. Recovery of cells can be temporarily achieved by the addition of Ca2+; permanent recovery requires incubation for some hours at 37 degrees C. 4. The possible significance of virally mediated permeability changes, with regard to clinical situations and to cell biology, is discussed.

Amino Acids↗
PubMed1976

Partial purification of amastigotes from cutaneous lesions of American leishmaniasis.

Amastigotes of Leishmania mexicana, L. mexicana amazonensis, L. brasiliensis, and L. enriettii were isolated from lesions in infected animals. Numbers of amastigotes recovered ranged from 1 X 10(7) to 7 X 10(8), depending on the strain of leishmania. Trypsinization disassociated the lesions and released the parasites. After 18 to 24 hr incubation at 37 C in tissue culture media with antibiotics, many of the intact host cells attached to the flask. Amastigotes were collected from the media in relatively pure preparations. Electron microscopy revealed no morphological alterations of the amastigotes and minimal contamination by membranes and cell fragments.

Animals↗
PubMedDate not supplied

The effect of culture and membrane potential on Go alpha expression in neonatal rat cardiac myocytes.

The effects of culture and membrane potential on Go alpha 39 expression were examined in neonatal rat cardiac myocytes. During six days of culture, the amount of Go alpha 39 in myocytes increased six-fold. The increase in Go alpha 39 appeared to be programmed, since Go alpha 39 of rat hearts also increased in vivo within three days after birth before declining by six days after birth. Furthermore, the age of the rat from which cardiac myocytes were isolated determined the amount of Go alpha 39 that accumulated in cultured cells with myocytes from two day-old rats producing more Go alpha 39 than myocytes from six day-old rats. In addition, agents which alter membrane potential (KCl and bupivacaine) inhibited the accumulation of Go alpha 39 in cultured myocytes. In an attempt to identify the signaling pathway in which cardiac Go alpha 39 is involved, muscarinic receptor-stimulated inositol phosphate production was examined, but was found to be comparable in myocytes that had six-fold differences in Go alpha 39 content. Thus Go alpha 39 does not appear to couple muscarinic receptors to phospholipase C in rat cardiac myocytes.

Animals↗