Helen M. Garnett

Effect of in vivo exposure to benzene on the characteristics of bone marrow adherent cells

The effect of benzene on the adherent cell population, cultured from the bone marrow of exposed mice was investigated in the presence and absence of hydrocortisone. The adherent CFUs from exposed animals did not differ either in numbers or self-replicate ability to those derived from shown exposed animals. Adherent layers from mice exposed to 100 or 400 pp-benzene were devoid of fat cells regardless of the presence or absence of hydrocortisone. Hydrocortisone was shown to influence the proportion of acid phosphatase-positive cells derived from benzene-exposed animals. Those results suggest that benzene exposure may influence the bone marrow stromal cells.

Hybridization of Pichia stipitis with its presumptive imperfect partner Candida shehatae

SummaryA triauxotrophic strain of the D-xylose fermenting yeast Pichia stipitis, was hybridized with diauxotrophic strains of its presumptive imperfect partner Candida shehatae through polyethylene glycol (PEG) induced protoplast fusion. A small fraction of prototrophic clones, selected on specific media, appeared to be “partial hybrids” as determined by cellular diphenylamine DNA quantitations after three passages on a complex medium. The hybrid nature of the Pichia-resembling fusants was confirmed by cell volume estimation, analysis of nuclear condition and the isolation of a variety of mutant recombinant phenotypic segregants by meiotic segregation, as well as induced and spontaneous mitotic segregation.

The early effects of human cytomegalovirus infection on macromolecular synthesis in human embryonic fibroblasts

SummaryCytomegalovirus inhibits overall protein and RNA synthesis within 3 hours of infection of human embryonic fibroblasts. This effect is similar to that seen in herpes infected cells.

Inhibitory effects of mersalyl and of antibodies directed against smooth-muscle myosin on a calcium adenosine triphosphatase of the plasma membrane from mouse liver cells

Abstract The effect of mersalyl and of antibodies, directed against smooth-muscle myosin and skeletal muscle myosin, on the (Ca2+ + Mg2+)-activated adenosine triphosphatase (Ca,Mg)ATPase) system of mouse liver plasma membranes has been studied. Antismooth-muscle myosin inhibited by 38.6% at optimum substrate concentration the (Ca,Mg)ATPase with a Km of 0.88 × 10−3 m . Mersalyl (0.5 m m ) also inhibited this enzyme, the percentage inhibition being 44.6% at optimal substrate concentration. These results suggest the presence of a smooth-muscle myosin-like protein in the plasma membrane of mouse liver cells which has an associated (Ca,Mg)ATPase activity.

Early alterations in the morphology of cytomegalovirus-infected human fibroblasts.

Cytomegalovirus-infected human fibroblasts developed large numbers of fine microvilli within 90 min after addition of virus. The structure of these microvilli gradually changed as the infection proceeded, although the infected cells were easily detected by their large number of processes. These processes may be involved in the increased transport of ions and nutrients into the infected cell.

Influence of a Fibroblastoid Cell Line Derived from Murine Bone Marrow (H-1 Cells) on Stem Cell Proliferation

Abstract A murine fibroblastoid cell line (H-1) with properties similar to those of adventitial reticular cells can support granulopoiesis and the development of mononuclear phagocytes in vitro. In the current study the effect of these cells on stem cell maintenance in vitro was assessed. The H-1 cells were unable to support CFUs replication in liquid culture, while treatment of some stem cells with H-1 conditioned medium appeared to inhibit their proliferation.

The effect of arginine deprivation on the cytopathogenic effect and replication of human cytomegalovirus.

SummaryArginine is necessary for the development of the cytopathogenic effect of human cytomegalovirus in human embryonic fibroblasts. It is also required, though in greater concentrations, for the production of infective virions, the requirement being at an early stage of replication. Inhibitor studies suggested that this block in replication caused by arginine deficiency was prior to the formation of viral DNA. Withdrawal of arginine from the medium 24 or 48 hours after infection resulted in a decline in virus production indicating that the continued presence of the amino acid is necessary for constant virus production. Infected cultures deprived of arginine could be stimulated to produce cytopathic effects and infective virions by replacement of the amino acid even eight days after inoculation, demonstrating that the information for cytomegalovirus replication remains intact within the cell. This establishment of latencyin vitro may be related to the ability of the virus to establish a similar statein vivo.

Energy-dependent accumulation of Ca2+ by human embryonic lung fibroblasts.

Human embryonic fibroblasts accumulate Ca2+ in the presence of extracellular ATP and Mg2+, the uptake being maximal at 3 mM ATP. Iodoacetic acid, oligomycin and temperatures of 2 degrees C all inhibit the ATP-potentiated uptake suggesting that an active process may be involved in the transport of Ca2+ into these cells under certain conditions.

Inhibition of energy-dependent Ca2+ accumulation in fibroblasts by smooth muscle antibodies

An antibody prepared against smooth muscle myosin interferes with active Ca2+ accumulation of fibroblasts. This provides further evidence for the existence of myosin at the cell surface.