Search PubMed⌕ Search

Biomedical subjects

G B Price

Publications and source records attributed to G B Price.

At least 91 records · Page 5Linked to original sources
PubMed1978

Structure analysis of small proteins by electron microscopy: valinomycin, bacitracin and low molecular weight cell growth stimulators.

Dark field electron microscopy was combined with optical filtering to study at high resolution the structure of the cyclopeptide antibiotics, bacitracin and valinomycin, and two proteins of unknown structure, LMW-CSA N and B, low molecular weight granulocyte colony stimulating activity isolated from medium conditioned with normal or leukemic leukocytes. For bacitracin and valinomycin the images faithfully represented the known structural features at a resolution of 0.5 nm or better, depicting a two-ring structure for bacitracin, as well as the position of the potassium ion in valinomycin. Both proteins of unknown structrue had at least one cyclic peptide portion. LMW-CSA N had a size of 2.0 nm, LMW-CSA B of 2.4 nm. A potential site of the calcium ionophoric activity in the latter protein was found to be in the larger of the two ring portions constituting the molecule.

Bacitracin↗
PubMed1978

The production of hemopoietic growth factors by PHA-stimulated leukocytes.

Conditioned medium from cultures of phytohemagglutinin-stimulated leukocytes has been assessed for its content of factors able to stimulate either colony formation by human granulopoietic progenitor cells, or 3H-thymidine incorporation by peripheral leukocytes from leukemic patients. The cell concentration, concentration of phytohemagglutinin and time required for optimal production of factors were investigated. Production of both classes of factors was found to be insensitive to inhibitors of cell proliferation and DNA synthesis, but sensitive to inhibition of protein synthesis by cycloheximide. The production of colony stimulating activity showed a markedly greater sensitivity to cycloheximide than did production of thymidine-incorporating activity. For cycloheximide and most of the other inhibitors studied, factor production by leukemic cell populations was affected to a somewhat greater extent than production by normal leukocytes. Separation by velocity sedimentation of the cells responsible for production provided no evidence for distinct classes of cells producing these two classes of factors.

Cell Division↗
PubMed1977

Measurement of cytoplasmic fluorescence depolarization of single cells in a flow system.

We have built a flow system in which we can analyze and sort individual viable cells on the basis of their cytoplasmic microviscosity. The average cytoplasmic microviscosity (or cytoplasmic structuredness) of a cell can be quantitated by exciting fluorescein molecules in the cytoplasm of the cell with a polarized light source and measuring the extent of depolarization of the fluorescent signal. Changes in the state of a cell (e.g., the reception of a signal inducing the cell to differentiate) often appear to be associated with changes in cytoplasmic microviscosity, these changes being detectable within hours of the inducing signal. An example of one such change is presented.

Bone Marrow↗
PubMed1977

Chronic myeloid leukemia: physical and functional similarities to acute leukemia.

Blast crisis, closely resembling acute leukemia, is the usual terminal event in chronic myeloid leukemia. Using physical ("fingerprint") and cultural (colony-forming) methods, we have demonstrated distinctive patterns in the stable phase of chronic myeloid leukemia and in blast crisis. An unusual fingerprint alteration preceding the onset of the terminal phase is noted, and cell culture perturbation is evident at different stages of the disease. Our findings indicate that the application of these methods to the study of hemopoietic disorders is valid, and suggest that the use of such techniques may allow a better understanding of the complex cellular events occurring in the course of chronic myeloid leukemia.

Acute Disease↗
PubMed1977

Serologic identification of hemopoietic progenitor cell antigens common to mouse and man.

An immunologic approach to the identification of human hemopoietic stem cell antigens has yielded two types of antisera. Both recognize antigens on hemopoietic progenitors which are identical or cross-reactive with determinants on sperm, brain, and, across the species barrier, with murine hemopoietic stem cells (CFU-S). The first antiserum was the result of an autoimmune reaction in a post-vasectomy patient. The second was produced in rabbits after injection of human brain cells.

Animals↗
PubMed1976

An approach to human preleukemia using cell culture studies.

Cell culture methods applied to the study of acute leukemia have indicated the presence of many abnormalities. Utilizing this knowledge, we have applied cell culture techniques to the evaluation of a patient population with a recognized risk of developing leukemia. We demonstrate that cultural abnormalities present in some patients with sideroblastic anemia are similar to those seen in acute leukemia, and that these perturbations may be shown before leukemia develops. This study suggests that cell culture abnormalities may reflect mechanisms operative in vivo, and preceding the development of overt leukemia.

Bone Marrow↗
PubMed1976

Cellular subclasses in human leukemic hemopoiesis.

Cellular organization and communication in leukemic hemopoiesis may be compared with its counterpart in normal hemopoiesis. Results obtained using cell culture methods have provided some support for the view that leukemic hemopoiesis, like normla hemopoiesis, may involve 3 levels of differentiation: leukemic stem cells, committed leukemic progenitors, and more mature cells. Evidence is also beginning to emerge that leukemic populations may be regulated by messages from the environment in a manner analogous to normal hemopoiesis. The apparent similarities between leukemic and normal hemopoiesis raise, the possibility that the target cell for leukemic transformation is the normal pluripotent stem cell. The development of culture methods for the production of leukovirus-like particles from human leukemic cells provides a possible first step toward the direct identification of leukemic target cells.

Anemia, Sideroblastic↗
PubMed1976

Stem cell characterization of neutropenia: velocity sedimentation and mass culture analysis.

Human bone marrow obtained from patients with neutropenia contains a cell population which is absent or diminished in normal marrow. The abnormal population is composed of cells of volume 200-300 mum3 which sediment at 5-5 to 8-5 mm/h. Normal marrow contains one cell class giving rise to increased numbers of grnaulocyte colonies after mass culture, while marrow obtained from neutropenic patients, or from patients with marrow regeneration, shows two such populations; one of these cell classes corresponds to the abnormally large cells demonstrated on velocity sedimentation analysis. This population of large cells may represent a group of either self-renewing cells related to the committed granulocyte progenitors or the pluripotent stem cell.

Adult↗
PubMed1976

Human preleukaemia cell culture studies in sideroblastic anaemia.

Cell structure abnormalties are found in acute leukaemia and preleukaemic states. Studies on bone marrow cells and peripheral leucocytes of 4 patients with idiopathic acquired sideroblastic anaemia showed patterns in cell culture similar to those reported in acute leukaemia: 2 of these patients later developed leukaemia. Other patients with idiopathic, secondary or congenital sideroblastosis showed no such cell culture abnormalities, and none developed leukaemia. Studies such as this suggest that cell culture methods detect altered cellular function preceding overt leukaemia and that these abnormal findings may be helpful in the evaluation of patient groups with an increased incidence of leukaemia.

Anemia, Sideroblastic↗
PubMed1976

Cross reactivity of human beta2-microglobulin with human granulocyte colony-stimulating activity.

Effects of antisera to human beta2-microglobulin (beta2 m) on factors able to stimulate colony formation in culture by human granulopoietic progenitor cells were investigated. The colony-stimulating activity (CSA) present in media conditioned by cultures of human peripheral leukocytes was suppressed by treatment with anti-beta2m. This inhibition was not due to a direct effect on the granulopietic progenitor cells; controls to test for cytotoxicity and for noncytotoxic inhibition of the progenitor cells by anti-beta2m yielded negative results. These experiments provide evidence for a relationship between human CSA and beta-microglobulin, and suggest a possible analogy between molceules involved in the in vitro regulation of granulopoiesis and products of the major histocompatibility gene complex.

Animals↗
PubMed1975

The isolation and properties of granulocytic colony-stimulating activities from medium conditioned by human peripheral leucocytes.

The colony-stimulating activity detected by its ability to promote colony formation by human granulopoietic progenitor cells was partially purified from medium conditioned by human peripheral leucocytes. The purification procedure utilized (NH4)2SO4 precipitation, DEAE-cellulose chromatography, hydroxyapatite chromatography and gel filtration on Sephadex G-150 and yielded a purification of about 1000-fold. The medium from cultures of non-leukaemic cells contained three molecular species of colony-stimulating activity with approximate molecular weights of 93000, 36500 and 14700. On the basis of their sensitivity to enzymes, these species of activity appeared to be proteins. In contrast, medium from cultures of leukaemic cells contained only one detectable molecular species with colony-stimulating activity, usually with an approximate molecular weight of 36500. The results are discussed in relation to concurrent studies on the association of the different species of colony-stimulating activity with the cell surface membrane.

Bone Marrow Cells↗
PubMed1975

Cell membranes as sources of granulocyte colony stimulating activities.

Subcellular localization of factors associated with stimulation of granulocyte progenitors (CFU-c) to form colonies in vitro was investigated. Human peripheral blood leukocytes were fractionated into three subcellular fractions. After solubilization with sodium dodecyl sulfate, fractions were assessed for ability to stimulate colony formation by CFU-c. The fraction containing cell membranes proved to be the richest source of stimulating factors. Apparent molecular weights for these factors as determined by gel filtration were equivalent to those obtained for factors from purified peripheral leukocyte conditioned medium. The results suggest that at least some granulocyte colony-stimulating factors should be regarded as membrane-active agents.

Bone Marrow↗
PubMed1975

Regulation of blood cell diferentiation.

The hemopoietic (blood forming) system contains pluripotent stem cells able to give rise to a variety of differentiated progeny, including erythrocytes, granulocytes, megakaryocytes, monocytes, macrophages, and possible other cell types. Although a good deal is known about cell lineage relationships in the hemopoietic system, only limited information is available about the mechanisms regulating the proliferation and differentiation of the stem cells and their progeny. An approach to this latter problem has been provided by the develoment of new techniques for the cultivation of hemopoietic cells in short-term cultures. In such cultures, the proliferation and differentiation of hemopoietic cells can be studied under controlled conditions. Two areas of investigation show particular promise: elucidation of the role of the cell surface membrane in regulation; and the possible development, through a detailed investigation of the properties of leukoviruses, of new methods for the genetic analysis of hemopoietic cells.

Animals↗