Incorporation Of 75Se-selenomethionine Research Articles

Interleukin-1 beta (IL-1 beta) induces thrombocytosis in mice: possible implication of IL-6

We administered recombinant human interleukin-1 beta (IL-1 beta), the common mediator of inflammation process, to C57B1/6 male mice (0.5 microgram, every 12 hours over five times) intraperitoneally and consequently induced a remarkable thrombocytosis. Day 1 was designated as the following day of the last injection in the morning. A significant thrombocytosis was observed on days 1 through 5 with a peak on day 2 (162 +/- 9 x 10(4)/mm3) compared with the control mice injected with heated IL-1 beta (101 +/- 11 x 10(4)/mm3). A striking increase in mean size of marrow megakaryocytes was noted on days 1 and 2. The incorporation of 75Se-selenomethionine into circulating platelets as a measure of platelet production was about 2.3 times higher in IL-1 beta-treated mice than in control mice. To determine which factor(s) is responsible for elicited thrombocytosis, the in vitro studies and bioassays for several hematopoietic factors were performed. IL-1 beta by itself did not stimulate megakaryocytopoiesis in vitro, suggesting that the thrombocytosis is attributed to other factor(s) via IL-1 beta stimulation. Serum colony-stimulating factor (CSF) activity after a single IL-1 beta (0.5 microgram) injection, monitored by colony assay with 10% tested serum, peaked at 3 hours. Formed colonies were mostly granulocyte (G) and granulocyte-macrophage (GM)-types, and studies using rabbit anti-mouse GM-CSF serum or using human marrow as target cells showed that the CSF activity of the tested serum consisted of, at least, GM-CSF and G-CSF. Addition of IL-3 concomitantly with the tested serum gave rise to a greater number of megakaryocytic colonies. Serum IL-3, monitored by IL-3-dependent cell line 32D clone 5, and erythropoietin activities were not detected at serum level in IL-1 beta-treated mice. Serum IL-6 assay by IL-6- dependent mouse hybridoma cell line MH-60.BSF2 showed high levels of the tested serum with a peak at 2.5 hours with no detection at 10 hours after the injection. Heated IL-1 beta caused an increase of neither IL- 6 nor CSF activities. Our data suggest that the thrombocytosis induced by IL-1 beta is mediated by IL-6 or a combination of IL-6 and other cytokine(s), and that IL-6 may play a regulatory role in platelet production in vivo.

Interleukin-1β (IL-1β) Induces Thrombocytosis in Mice: Possible Implication of IL-6

AbstractWe administered recombinant human interleukin-1β (IL-1β), the common mediator of inflammation process, to C57B1/6 male mice (0.5 µg, every 12 hours over five times) intraperitoneally and consequently induced a remarkable thrombocytosis. Day 1 was designated as the following day of the last injection in the morning. A significant thrombocytosis was observed on days 1 through 5 with a peak on day 2 (162 ± 9 × 104/mm3) compared with the control mice injected with heated IL-1β (101 ± 11 × 104/mm3). A striking increase in mean size of marrow megakaryocytes was noted on days 1 and 2. The incorporation of 75Se-selenomethionine into circulating platelets as a measure of platelet production was about 2.3 times higher in IL-1β– treated mice than in control mice. To determine which factor(s) is responsible for elicited thrombocytosis, the in vitro studies and bioassays for several hematopoietic factors were performed. IL-1β by itself did not stimulate megakaryocytopoiesis in vitro, suggesting that the thrombocytosis is attributed to other factor(s) via IL-1β stimulation. Serum colony-stimulating factor (CSF) activity after a single IL-1β (0.5 µg) injection, monitored by colony assay with 10% tested serum, peaked at 3 hours. Formed colonies were mostly granulocyte (G) and granulocyte-macrophage (GM)-types, and studies using rabbit anti-mouse GM-CSF serum or using human marrow as target cells showed that the CSF activity of the tested serum consisted of, at least, GM-CSF and G-CSF. Addition of IL-3 concomitantly with the tested serum gave rise to a greater number of megakaryocytic colonies. Serum IL-3, monitored by IL-3-dependent cell line 32D clone 5, and erythropoietin activities were not detected at serum level in IL-1β–treated mice. Serum IL-6 assay by IL-6-dependent mouse hybridoma cell line MH-60.BSF2 showed high levels of the tested serum with a peak at 2.5 hours with no detection at 10 hours after the injection. Heated IL-1β caused an increase of neither IL-6 nor CSF activities. Our data suggest that the thrombocytosis induced by IL-1β is mediated by IL-6 or a combination of IL-6 and other cytokine(s), and that IL-6 may play a regulatory role in platelet production in vivo.

Stimulation of fibrinogen biosynthesis by fibrinogen fragments D and E

Infusions of either fibrinogen fragment D or fibrinogen fragment E into rabbits were followed by increases in fibrinogen synthesis determined by the rate of incorporation of 75Se-selenomethionine into circulating fibrinogen. The degree of stimulation was proportional to the amount of protein infused. When 4.5 mg of each fibrinogen fragment was administered separately to different groups of animals, fibrinogen fragment D was associated with a fourfold increase in fibrinogen synthesis above that in the control animals compared with 1.5-fold increase induced by fragment E. Fragments D and E were assayed for bound sialic acid, the absence of which facilitates binding, transport and catabolism of many circulating glycoproteins by the liver. Fibrinogen fragment D contained 1.3% sialic acid compared to 1.4% in fragment E. These data indicate conservation of sialic acid during plasmic digestion of fibrinogen. The capacity of these glycopolypeptide fragments to stimulate fibrinogen synthesis appears unrelated to the nearly identical quantities of N-acetyl neuraminic acid found in each fragment.

Rat Kappa Chain Allotypes. IV. Monoclonal Antibodies to Distinct RI-1b Specificities

Four hybridomas are described which produce antibodies to the RI-1b rat kappa chain allotype. Three are rat alloantibodies of KG2b isotype, one is a mouse heteroantibody of KG2a isotype. These antibodies were labeled by incorporation of 75Se-selenomethionine and their specificity determined by a plate-binding assay. Inhibition studies using partially cross-reactive sera from Asian and Australian Rattus show that these four hybridomas detect four distinct RI-1b specificities. Differences in the slopes of the inhibition curves indicate that each of the specificities may exist in more than one form. In addition, in the form of 125I-labeled antibodies, two of these hybridomas show a high degree of specificity in binding to Ig-bearing lymphocytes from spleen and lymph nodes. These hybridomas will therefore be useful not only in studies on the phylogenetic distribution of RI-1 specificities but also in replacing conventional antisera for immunochemical and cellular immunological studies.

Incorporation of 75Se-Selenomethionine into Human Apoproteins: III. Kinetic Behavior of Isotopically Labeled Plasma Apoprotein in Man

The metabolism of lipoprotein-apoprotein was examined in four subjects with normal lipid metabolism and in one subject with type II hyperlipemia by means of isotopic tracer methodology. Studies were performed after intravenous injection of a radioactive amino acid precursor for apoprotein synthesis (75Se-selenomethionine), in both the basal state and following the acute injection of intravenous heparin. Computer technics were used to evaluate a series of multicompartmental models, and a general model is proposed that yields optimum fitting of experimental data for serum free amino acid precursor, very-low-density lipoprotein-apoprotein (VLD-apoprotein), and low-density lipoprotein-apoprotein (LDL-apoprotein) in man. The analysis demonstrates that approximately half of the transport of 75Se-apoVLDL from the plasma VLDL pool is converted to 75Se-apoLDL. The acute injection of heparin in two normal subjects results in a two-and-a-half-fold increase in this rate of conversion of 75Se-apoVLDL to 75Se-apoLDL. 75Se-apoLDL is metabolized by rapid transport into a recycling extravascular pool and by irreversible catabolism. The fractional rate of recycling is large relative to the fractional rate of catabolism of apoLDL (3.7:1.0), suggesting extravascular recycling as a potential site of regulation of the plasma concentration of apoLDL. In a patient with type II hyperlipemia, the extravascular recycling pathway is reduced and is not corrected with D-thyroxine therapy. However, this therapy did reduce conversion of apoVLDL to apoLDL in this type II patient. The kinetic data support the validity of the compartmental model in simulating both normal and pathologic apoprotein metabolism and that perturbation of physiology seen with heparin injection and D-thyroxine therapy. These data support a quantitative role of apoVLDL as a precursor of apoLDL and identify an important recycling pathway of apoLDL metabolism in addition to that of catabolism.

Incorporation of 75Se-selenomethionine into human apoproteins. III. Kinetic behavior of isotopically labeled plasma apoprotein in man

Incorporation of 75Se-selenomethionine into human apoproteins. III. Kinetic behavior of isotopically labeled plasma apoprotein in man

Incorporation of 75Se-selenomethionine into human apoproteins. II. Characterization of metabolism of very-low-density and low-density lipoproteins in vivo and in vitro

Incorporation of 75Se-selenomethionine into human apoproteins. II. Characterization of metabolism of very-low-density and low-density lipoproteins in vivo and in vitro

Incorporation of 75Se-Selenomethionine into Human Apoproteins: II. Characterization of Metabolism of Very-low-density and Low-density Lipoproteins in Vivo and in Vitro

This investigation is designed to explore the potential role of apo VLDL as a precursor of a polypeptide component of human LDL. Attention was directed to the chromatography-defined Sf-I polypeptide fraction of apo VLDL, which has been previously shown to be immunologically and chemically indistinguishable from the major component of apoLDL.1-3 In VLDL isolated from bloow drawn within two hours following 75Se-SM injection, the Sf-I polypeptide fraction of apo VLDL was highly enriched with isotope, providing an appropriate preparation for in-vitro tracer studies. Conversion of 75Se-VLDL to 75Se-LDL occurred in vitro in the presence of normal plasma at 37 degrees C., and this conversion was augmented by post-heparin plasma. No conversion to HDL lipoproteins could be detected. Injection of heparin in vivo resulted in acute reciprocal changes in the radioactivity contained within serum apo VLDL and apoLDL. These findings suggest that a component of the Sf-I polypeptide fraction of apo VLDL can be metabolized into the apoprotein of LDL in man. Thus, the biochemical and immunologic similarities between the Sf-I fractions of apoVLDL and apoLDL may result from a physiologic "precursor-product" relationship between the apoprotein moieties of these two lipoprotein species. A method for further investigation of the metabolism of human apoprotein is suggested.

Incorporation of 75Se-selenomethionine into human apoproteins. I. Characterization of specificity in very-low-density and low-density lipoproteins

Incorporation of 75Se-selenomethionine into human apoproteins. I. Characterization of specificity in very-low-density and low-density lipoproteins

75Se-selenomethionine in hepatic focal lesions

The focal lesion of the liver is usually characterized by the absence of the liver's uptake of radioactive scanning agents. In the focal lesion, the incorporation of 75Se-selenomethionine is related to its vascularity and capacity to metabolize methionine. Modification of the rectilinear scanner permits it to function in a dual-channel subtraction mode, to subtract 198Au from 75Se in the liver, and to present the display of the liver in one color and the selenium in the pancreas and the focal lesion in another. The avascular lesions, including cysts, abscesses, scars, pseudotumors, and extrinsic pressure defects, show little or no 75Se activity. Metastatic lesions may have varying levels of selenium concentration. The hepatocellular carcinoma concentrates selenium in amounts equal to the normal hepatic parenchyma and can only be visualized in the 75Se-selenomethionine scan by the subtraction technique. The correlation between vascularity and 75Se concentration is high but not necessarily directly proportional, and in specific instances may be poorly correlated. Knowledge of the selenomethionine content in a focal defect is considered to enhance the diagnostic value of liver scanning.

Incorporation of 75Se-Selenomethionine and 35S-Methionine into Chicken Egg White Proteins

After the simultaneous injection of trace amounts of 75Se-selenomethionine and 35S-methionine into the wing vein of the hen, the extent and mode of incorporation of both amino acids into the egg white proteins was studied. The results obtained appear to indicate that the selenomethionine is incorporated in a manner indistinguishable from that of methionine. All of the 75Se associated with the proteins was identified as 75Se-selenomethionine. The amino acid appears to be bound to the protein by covalent linkages since it is not removed by dialysis, gel-filtration or precipitation by trichloroacetic acid. The ratio of 35S/75Se of the total egg white proteins is approximately maintained during several manipulations of the proteins including the isolation of crystalline ovalbumin and in the amino acids liberated during the proteolytic digestion of this protein. The only gross difference observed in the behavior of both amino acids is the absence from the protein hydrolysates of any 75Se-selenocysteine although 35S-cysteine was detected.