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Articles 421 - 434 of 434
Full-Text Articles in Medicine and Health Sciences
Osteogenesis Imperfecta. The Position Of Substitution For Glycine By Cysteine In The Triple Helical Domain Of The Pro Alpha 1(I) Chains Of Type I Collagen Determines The Clinical Phenotype., Barbra J. Starman, David Eyre, Harry Charbonneau, Maria Harrylock, Mary Ann Weis, Lester Weiss, John M. Graham Jr., Peter H. Byers
Osteogenesis Imperfecta. The Position Of Substitution For Glycine By Cysteine In The Triple Helical Domain Of The Pro Alpha 1(I) Chains Of Type I Collagen Determines The Clinical Phenotype., Barbra J. Starman, David Eyre, Harry Charbonneau, Maria Harrylock, Mary Ann Weis, Lester Weiss, John M. Graham Jr., Peter H. Byers
Dartmouth Scholarship
Skin fibroblasts grown from three individuals with osteogenesis imperfecta (OI) each synthesized a population of normal type I collagen molecules and additional molecules that had one or two alpha 1(I) chains that contained a cysteine residue within the triple-helical domain, a region from which cysteine normally is excluded. The patients had very different phenotypes. One patient with OI type I had a population of alpha 1(I) chains in which glycine at position 94 of the triple helix was substituted by cysteine; a patient with OI type III had a population of alpha 1(I) chains in which glycine at position 526 …
Camp Antagonizes Interleukin 2-Promoted T-Cell Cycle Progression At A Discrete Point In Early G1., Kirk W. Johnson, Bruce H. Davis, Kendall A. Smith
Camp Antagonizes Interleukin 2-Promoted T-Cell Cycle Progression At A Discrete Point In Early G1., Kirk W. Johnson, Bruce H. Davis, Kendall A. Smith
Dartmouth Scholarship
T lymphocytes are stimulated to proliferate in an autocrine/paracrine manner by the lymphokine interleukin 2 (IL-2). In seeking further insight into the mechanisms by which IL-2 induces progression of T cells through the G1 phase of the cell cycle, studies were performed with agents that increase cellular adenosine 3',5'-cyclic monophosphate (cAMP), a well-known inhibitor of lymphocyte growth. The addition of dibutyryl-cAMP, cholera toxin, forskolin, or 3-isobutyl-1-methylxanthine to an IL-2-dependent murine T-cell line evoked a dose-related suppression of S-phase transition without affecting cellular viability. Moreover, elevation of cAMP levels led to an accumulation of uniformly small cells, suggesting an arrest in …
K+ Efflux In Nih Mouse 3t3 Cells And Transformed Derivatives: Dependence On Extracellular Ca2+ And Phorbol Esters., Martin Lubin
K+ Efflux In Nih Mouse 3t3 Cells And Transformed Derivatives: Dependence On Extracellular Ca2+ And Phorbol Esters., Martin Lubin
Dartmouth Scholarship
In culture medium deficient in Ca2+, NIH mouse 3T3 cells lose K+, gain Na+, and stop growing. A marked increase in the rate of K+ efflux accounts for this loss; Na+, K+-ATPase pump activity increases but does not fully compensate for enhanced K+ efflux. Phorbol esters and cycloheximide inhibit K+ loss in Ca2+-deficient medium. Phorbol esters inhibit K+ efflux from human fibroblasts as well, even at physiological levels of Ca2+. Two cell lines derived from NIH-3T3, one transformed by a simian virus 40 deletion mutant, the other by the polyoma virus oncogene encoding the middle-sized tumor antigen, retain K+ and …
Regulation Of Lymphokine Production And Human T Lymphocyte Activation By 1,25-Dihydroxyvitamin D3. Specific Inhibition At The Level Of Messenger Rna., William F.C. Rigby, Sylvia Denome, Michael W. Fanger
Regulation Of Lymphokine Production And Human T Lymphocyte Activation By 1,25-Dihydroxyvitamin D3. Specific Inhibition At The Level Of Messenger Rna., William F.C. Rigby, Sylvia Denome, Michael W. Fanger
Dartmouth Scholarship
The steroid hormone, 1 alpha,25-dihydroxyvitamin D3 (calcitriol), has been shown to inhibit T cell proliferation, primarily through inhibition of interleukin 2 (IL-2) production. In these experiments, we show that calcitriol also markedly inhibited production of the lymphokine, gamma interferon (IFN-gamma), by activated human T lymphocytes. Regulation of both IL-2 and IFN-gamma production as well as transferrin receptor (TfR) expression by calcitriol was apparent at the messenger RNA (mRNA) level as determined by Northern blotting. The decrease in IL-2 and IFN-gamma mRNA that occurred with calcitriol treatment was coordinate and not apparent up to 12 h after phytohemagglutinin stimulation, whereas decreased …
Recognition And Characterization Of Stage-Specific Oocyst/Sporozoite Antigens Of Toxoplasma Gondii By Human Antisera., Lloyd H. Kasper, Patricia L. Ware
Recognition And Characterization Of Stage-Specific Oocyst/Sporozoite Antigens Of Toxoplasma Gondii By Human Antisera., Lloyd H. Kasper, Patricia L. Ware
Dartmouth Scholarship
Human infection with Toxoplasma gondii is presumed due to the ingestion of either tissue cysts containing bradyzoites or oocyst/sporozoites that are excreted in the feces of infected cats. The incidence of human infection in the general population by either of these routes is unknown. We have previously described unique stage-specific oocyst/sporozoite antigens identified by murine hybridoma monoclonal antibodies. We obtained acute and convalescent antitoxoplasma antisera from patients in an epidemiologically well-documented outbreak of oocyst-transmitted infection associated with the ingestion of contaminated water. An enzyme-linked immunosorbent assay comparing equal numbers of tachyzoites (invasive stage) and oocyst/sporozoite (excreted stage) indicated that these …
Heterogeneity Of Clonogenic Cells In Acute Myeloblastic Leukemia., Kert D. Sabbath, Edward D. Ball, Peter Larcom, Roger B. Davis, James D. Griffin
Heterogeneity Of Clonogenic Cells In Acute Myeloblastic Leukemia., Kert D. Sabbath, Edward D. Ball, Peter Larcom, Roger B. Davis, James D. Griffin
Dartmouth Scholarship
The expression of differentiation-associated surface antigens by the clonogenic leukemic cells from 20 patients with acute myeloblastic leukemia (AML) was studied with a panel of seven cytotoxic monoclonal antibodies (anti-Ia, -MY9, -PM-81, -AML-2-23, -Mol, -Mo2, and -MY3). The surface antigen phenotypes of the clonogenic cells were compared with the phenotypes of the whole leukemic cell population, and with the phenotypes of normal hematopoietic progenitor cells. In each case the clonogenic leukemic cells were found within a distinct subpopulation that was less "differentiated" than the total cell population. Clonogenic leukemic cells from different patients could be divided into three phenotype groups. …
Interleukin 2 Regulates Its Own Receptors., Kendall A. Smith, Doreen A. Cantrell
Interleukin 2 Regulates Its Own Receptors., Kendall A. Smith, Doreen A. Cantrell
Dartmouth Scholarship
The cell surface density of high-affinity membrane receptors for the T-lymphocytotrophic hormone interleukin 2 (IL-2) determines the rate of T-cell-cycle progression. Since 10-fold greater numbers of IL-2 receptor molecules were found by using a radiolabeled monoclonal antibody reactive with IL-2 receptors (anti-Tac) compared with binding of IL-2, the functional relationship of the binding sites recognized by both of these ligands was assessed. In the presence of cycloheximide, IL-2 binding sites declined with a half-time (t1/2) of 2.6 hr, whereas the decay of anti-Tac binding sites was much slower (t 1/2 = 6.4 hr). Moreover, after limited membrane proteolysis, the half-time …
Inhibition Of T Lymphocyte Mitogenesis By 1,25-Dihydroxyvitamin D3 (Calcitriol)., William F.C. Rigby, Terryl Stacy, Michael W. Fanger
Inhibition Of T Lymphocyte Mitogenesis By 1,25-Dihydroxyvitamin D3 (Calcitriol)., William F.C. Rigby, Terryl Stacy, Michael W. Fanger
Dartmouth Scholarship
Recent studies have suggested that vitamin D may have other important biologic activities in addition to its well-characterized role in the maintenance of calcium homeostasis. Discovery of cytosolic receptors for vitamin D in human peripheral blood monocytes and lectin-stimulated lymphocytes prompted us to study the effects of 1,25-dihydroxyvitamin D3 (calcitriol), the most biologically active metabolite of vitamin D, upon phytohemagglutinin (PHA)-induced lymphocyte blast transformation. We have found that calcitriol is a potent inhibitor of PHA-induced lymphocyte proliferation, achieving 70% inhibition of tritiated thymidine incorporation after 72 h in culture. Furthermore, calcitriol suppressed interleukin-2 (IL-2) production by PHA-stimulated peripheral blood mononuclear …
Inhibition Of Growth Of Toxoplasma Gondii In Cultured Fibroblasts By Human Recombinant Gamma Interferon., E. R. Pfefferkorn, Paul M. Guyre
Inhibition Of Growth Of Toxoplasma Gondii In Cultured Fibroblasts By Human Recombinant Gamma Interferon., E. R. Pfefferkorn, Paul M. Guyre
Dartmouth Scholarship
The growth of Toxoplasma gondii in cultured human fibroblasts was inhibited by recombinant human gamma interferon at concentrations of 8 to 16 U/ml. The interferon was titrated by observing a total inhibition of parasite plaque formation 7 days after infection. Inhibition of the growth of T. gondii in the early days after infection was measured by marked reductions in the incorporation of radioactive uracil, a precursor that can only be used by the parasites. This assay showed that when cells were pretreated with gamma interferon for 1 day and then infected, inhibition of T. gondii growth could be readily detected …
Gamma Interferon Induces Monocytoid Differentiation In The Hl-60 Cell Line., Edward D. Ball, Paul M. Guyre, Li Shen, John M. Glynn, Charles R. Maliszewski, Paul E. Baker, Michael W. Fanger
Gamma Interferon Induces Monocytoid Differentiation In The Hl-60 Cell Line., Edward D. Ball, Paul M. Guyre, Li Shen, John M. Glynn, Charles R. Maliszewski, Paul E. Baker, Michael W. Fanger
Dartmouth Scholarship
We investigated the ability of purified, recombinant DNA-derived interferons (IFN) to induce phenotypic changes in cells of the HL-60 promyelocytic leukemia cell line. Changes in cell surface markers detected by monoclonal antibodies as well as morphologic, histochemical, and functional changes were monitored. We found that gamma-IFN, but not alpha- or beta-IFN, induced the expression of antigens characteristic of monocytes and granulocytes (AML-2-23, 63D3, and 61D3), as well as changes in morphology consistent with monocytoid differentiation. These included induction of alpha-naphthyl acetate esterase, increased cell size, and a decrease in azurophilic granules. The gamma-IFN dose dependency and time course of the …
Triggering Of The T3-Ti Antigen-Receptor Complex Results In Clonal T-Cell Proliferation Through An Interleukin 2-Dependent Autocrine Pathway., Stefan C. Meuer, Rebecca E. Hussey, Doreen A. Cantrell, James C. Hodgdon, Stuart F. Schlossman, Kendall A. Smith, Ellis L. Reinherz
Triggering Of The T3-Ti Antigen-Receptor Complex Results In Clonal T-Cell Proliferation Through An Interleukin 2-Dependent Autocrine Pathway., Stefan C. Meuer, Rebecca E. Hussey, Doreen A. Cantrell, James C. Hodgdon, Stuart F. Schlossman, Kendall A. Smith, Ellis L. Reinherz
Dartmouth Scholarship
Human T-cell clones and anti-T-cell-receptor antibodies (clonotypic) directed at surface receptors for antigen (T3-Ti molecular complex) as well as anti-interleukin 2 (IL-2) and anti-IL-2-receptor antibodies were utilized to investigate the mechanism by which alloantigens or antigen plus self-major histocompatibility complex (MHC) (i.e., physiologic ligand) trigger specific clonal proliferation. Soluble or Sepharose-bound anti-Ti monoclonal antibodies, like physiologic ligand, enhanced proliferative responses to purified IL-2 by inducing a 6-fold increase in surface IL-2 receptor expression. In contrast, only Sepharose-bound anti-Ti or physiologic ligand triggered endogenous clonal IL-2 production and resulted in subsequent proliferation. The latter was blocked by antibodies directed at either …
Interferon Gamma Blocks The Growth Of Toxoplasma Gondii In Human Fibroblasts By Inducing The Host Cells To Degrade Tryptophan., E. R. Pfefferkorn
Interferon Gamma Blocks The Growth Of Toxoplasma Gondii In Human Fibroblasts By Inducing The Host Cells To Degrade Tryptophan., E. R. Pfefferkorn
Dartmouth Scholarship
Treatment of human fibroblasts with human recombinant gamma interferon blocked the growth of Toxoplasma gondii, an obligate intracellular protozoan parasite. Growth of the parasite was measured by a plaque assay 7 days after infection or by the incorporation of [3H]uracil 1 or 2 days after infection. The antitoxoplasma activity induced in the host cells by gamma interferon was strongly dependent upon the tryptophan concentration of the medium. Progressively higher minimal inhibitory concentrations of gamma interferon were observed as the tryptophan concentration in the culture medium was increased. Treatment with gamma interferon did not make the cells impermeable to tryptophan. The …
Recombinant Immune Interferon Increases Immunoglobulin G Fc Receptors On Cultured Human Mononuclear Phagocytes, Paul M. Guyre, Peter M. Morganelli, Renee Miller
Recombinant Immune Interferon Increases Immunoglobulin G Fc Receptors On Cultured Human Mononuclear Phagocytes, Paul M. Guyre, Peter M. Morganelli, Renee Miller
Dartmouth Scholarship
Although recent studies suggest that interferons can increase the number of IgG Fc receptor (FcR gamma) sites on mouse macrophages, direct assessment of similar effects on human mononuclear phagocytes is lacking. We therefore measured the specific binding of 125I- and fluorescein-labeled IgG1 to human monocytes and leukemic cell lines after culture in vitro with highly purified human interferons. We report that natural and recombinant human gamma-interferon causes a dramatic (nearly 10-fold) increase in the number of FcR gamma on normal human monocytes and on the human cell lines HL-60 and U-937. Alpha and beta-interferons cause a modest but significant increase …
Proteins Antigenically Related To The Human Erythrocyte Glucose Transporter In Normal And Rous Sarcoma Virus-Transformed Chicken Embryo Fibroblasts., Donald W. Salter, Stephen A. Baldwin, Gustav E. Lienhard, Michael J. Weber
Proteins Antigenically Related To The Human Erythrocyte Glucose Transporter In Normal And Rous Sarcoma Virus-Transformed Chicken Embryo Fibroblasts., Donald W. Salter, Stephen A. Baldwin, Gustav E. Lienhard, Michael J. Weber
Dartmouth Scholarship
Antibody raised against the purified human erythrocyte glucose transporter specifically precipitated four proteins from normal and Rous sarcoma virus-transformed chicken embryo cells: a major protein of Mr 41,000 and minor proteins of Mr 68,000, 73,000, and 82,000. The Mr 41,000 and 82,000 proteins were found only in a membrane fraction, not in the soluble fraction, and displayed a heterogeneous mobility on NaDodSO4/polyacrylamide gel electrophoresis, suggesting glycosylation. The Mr 41,000 and 82,000 proteins were increased in amount after malignant transformation in direct proportion to the increase in hexose transport rate, and the increase was dependent on the expression of the src …