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J Morser

Publications and source records attributed to J Morser.

At least 55 records · Page 3Linked to original sources
PubMed1992

Structure-function studies of the epidermal growth factor domains of human thrombomodulin.

Structure-function relationships in the 6 epidermal growth factor-like domains of human thrombomodulin (TME, residues 227-462) were studied by deletion mutagenesis. Purified and characterised proteins were used for kinetic studies. Deletion of EGF1, EGF2 and residues 310-332 in EGF3 had no effect on thrombin binding (Kd) or on kcat/KM for protein C activation by the thrombin-thrombomodulin complex. Deletion of the rest of EGF3 and the interdomain loop between EGF3 and EGF4 had no effect on Kd but decreased kcat/KM to 10% of TME. Deletion of residues 447-462 of EGF6 had no effect on kcat/KM but increased Kd for thrombin approximately 6-fold. Thus, the region 333-350 in EGF3-4 is critical for protein C activation by the thrombin-thrombomodulin complex and the region 447-462 in EGF6 is critical for thrombin binding.

Base Sequence↗
PubMed1992

Oxidation of a specific methionine in thrombomodulin by activated neutrophil products blocks cofactor activity. A potential rapid mechanism for modulation of coagulation.

Endothelial thrombomodulin (TM) plays a critical role in hemostasis as a cofactor for thrombin-dependent formation of activated protein C, a potent anticoagulant. Chloramine T, H2O2, or hypochlorous acid generated from H2O2 by myeloperoxidase rapidly destroy 75-90% of TM cofactor activity. Activated PMN, the primary in vivo source of biological oxidants, also rapidly inactivate TM. Oxidation of TM by PMN is inhibited by diphenylene iodonium, an inhibitor of NADPH oxidase. Both Met291 and Met388 in the six epidermal growth factor-like repeat domain are oxidized; however, only substitutions of Met388 lead to TM analogues that resist oxidative inactivation. We suggest that in inflamed tissues activated PMN may inactivate TM and demonstrate further evidence of the interaction between the inflammatory process and induction of thrombotic potential.

Adult↗
PubMed1991

Intravenous recombinant soluble human thrombomodulin prevents venous thrombosis in a rat model.

Thrombomodulin is an endothelial surface thrombin receptor. Thrombin bound to thrombomodulin loses all procoagulant activity and instead activates the protein C anticoagulant pathway. We developed a recombinant thrombomodulin analog and compared the effects of recombinant thrombomodulin (100 micrograms/ea), saline (controls), recombinant hirudin (1.0 mg/kg), and heparin (100 units/kg) on thrombus formation, activated partial thromboplastin time, and tail transection bleeding time in a rat model of stasis-induced venous thrombosis. Results showed that thrombus was detected in the vena cava in six of the six rats treated with saline solution, in zero of the six rats treated with recombinant thrombomodulin (p less than 0.05), in one of six rats treated with recombinant hirudin (p less than 0.05), and in zero of six rats treated with heparin (p less than 0.05). The activated partial thromboplastin time in rats receiving recombinant thrombomodulin was slightly longer than controls (22 +/- 8 vs 37 +/- 6, p less than 0.05). The bleeding times in rats receiving recombinant thrombomodulin were approximately twice as long as controls (215 +/- 68 vs 545 +/- 173, p = 0.037). In all rats treated with recombinant hirudin or heparin, activated partial thromboplastin times were greater than 120 seconds and bleeding times were greater than 1200 seconds. We conclude that recombinant thrombomodulin inhibits venous thrombosis in a rat model with less prolongation of activated partial thromboplastin time and bleeding time than heparin or hirudin.

Animals↗
PubMed1990

Differential effect of platelets on plasminogen activation by tissue plasminogen activator, urokinase, and streptokinase.

In this report, we have examined the effects of platelets on plasminogen activation by different activators. Platelets enhance activation of plasminogen by both 1- and 2-chain tissue plasminogen activator (t-PA). The primary effect of platelets is to lower the Km with a corresponding 5-8-fold increase in the kcat/Km. The effect is saturable with respect to the platelet concentration. Platelets enhance activation of both glu- and lys-plasminogen by t-PA. Platelets have no effect on plasminogen activation by streptokinase, and high and low molecular weight urokinase. Thus, there are marked differences in the effects of platelets on plasminogen activation depending on the plasminogen activator. These differences are likely to reflect differences in the interaction between platelets and the plasminogen activators.

Blood Platelets↗
PubMed1983

Expression of interferon-alpha and interferon-beta genes in human lymphoblastoid (Namalwa) cells.

Treatment of human lymphoblastoid (Namalwa) cells with Sendai virus induced the coordinate synthesis of both IFN-alpha and IFN-beta interferon mRNAs. One sub-line of Namalwa cells (WRL) produced no IFN-beta activity, although IFN-beta mRNA was induced and was associated with polysomes. The IFN-alpha mRNA was heterogeneous, ranging in size over 1.20-1.35 X 10(3) bases, probably because of variation in the size of the transcribale DNA in the alpha-gene family. The IFN-beta mRNA was monodisperse with a size of 1.05 X 10(3) bases. The kinetics of accumulation and decay of both IFN-alpha and IFN-beta mRNAs, as assessed by hybridization with cDNA probes, were very similar to those of translatable interferon mRNA, as assessed by translation in Xenopus oocytes. Treatment of the cells with butyrate or 5'-bromodeoxyuridine increased the amount of hybridizable IFN-alpha and IFN-beta mRNA about 15-fold and 4-fold respectively, again demonstrating coordinate control of IFN-alpha and IFN-beta production.

Base Composition↗
PubMed1982

Protein synthesis in human lymphoblastoid cells (Namalwa) after treatment with butyrate and 5'-bromodeoxyuridine.

The pattern of protein synthesis has been compared in Namalwa cells following treatment with butyrate and 5'-bromodeoxyuridine (BrdUrd). Although these treatments cause a substantial increase in Sendai virus-induced interferon synthesis (up to 300-fold) we observed no comparable effect on the synthesis of other cellular proteins. Using two-dimensional gel electrophoresis we have investigated the proteins synthesised before and 8 h after Sendai virus infection of treated cells. Only 2 of the 300 most abundant cellular proteins were reproducibly affected, these always showed increased rates of synthesis in butyrate-treated cells. The most significant was a 3-4-fold enhancement in synthesis of a 35,000 molecular weight protein which we have called BEP35. On individual occasions treatment caused changes in the rates of synthesis of other proteins, these were not reproducible and involved less than 4% of the proteins investigated. None of the Sendai virus structural proteins or virus-induced cellular proteins were affected by the treatment. We conclude that butyrate and BrdUrd treatments have a relatively specific effect on the synthesis of interferon in Namalwa cells, as the majority of protein synthesis remains unaffected.

Bromodeoxyuridine↗
PubMed1982

Control of interferon mRNA levels and interferon yields in butyrate and 5'-bromodeoxyuridine-treated Namalwa cells.

Treatment of Namalwa cells with butyrate or 5'-bromodeoxyuridine (BrdUrd) before induction with Sendai virus caused an increase in the production of both interferon (IFN) and interferon mRNA (IFN mRNA). However, the increase in IFN mRNA did not completely account for the increase in IFN yield. The treatments did not affect the time course of IFN mRNA transcription and translation, or the association of IFN mRNA with polysomes. Likewise, the treatments did not alter the post-translational fate of the IFN produced. We conclude that butyrate and BrdUrd affect IFN production at the level of transcription or processing of IFN mRNA and suggest that increased efficiency of translation provides an additional level of control.

Bromodeoxyuridine↗
PubMed1982

The effect of hypertonic salt on interferon and interferon mRNA synthesis in human MG63 cells.

After infection with Sendai virus or Newcastle disease virus (NDV) strain F, human osteosarcoma MG63 cells produced large amounts of interferon-beta. Both interferon production and overall protein synthesis were strongly inhibited by hypertonic salt. Interferon mRNA synthesis, however, was little affected by hypertonic salt up to twice normal salt concentrations, although cellular RNA synthesis was inhibited under these conditions. The results are compared to those obtained with polyriboinosinic acid: polyribocytidylic acid copolymer [poly(rI) . poly(rC)] inductions of MG63 cells.

Cell Line↗
PubMed1982

Analysis and purification of human lymphoblastoid (Namalwa) interferon using a monoclonal antibody.

Highly purified interferon-alpha (IFN-alpha) prepared from a human lymphoblastoid line (Namalwa) was analysed by gel filtration and polyacrylamide gel electrophoresis (PAGE). Gel filtration separated the IFN-alpha into two peaks (A and B). All the components of peak A were retained by a monoclonal antibody (NK2) column, but some of those from peak B were not retained. The IFN that was not bound was active on mouse cells and could be resolved into two major bands by PAGE. The bound fraction (about 75% of the interferon protein) was purified by means of the monoclonal antibody column, although complete purification of crude interferon was not achieved in one passage.

Antibodies, Monoclonal↗
PubMed1982

Spontaneous production of gamma interferon and induced production of beta interferon by human T-lymphoblastoid cell lines.

Two human T-lymphoblastoid cell lines, CCRF/CEM and Molt 4, produced beta interferon (IFN-beta) upon infection with Sendai virus. Molt 4, but not CCRF/CEM, spontaneously produced up to 300 U of IFN-gamma per ml, apparently not contaminated with IFN-alpha or -beta. Phytohemagglutinin, a T-cell mitogen, did not stimulate IFN production in these lines. A third T-lymphoblastoid line, CCRF/HSB2, produced no IFN either spontaneously or after infection with Sendai virus or treatment with phytohemagglutinin. The Molt 4 cells contained an mRNA which could be translated by oocytes to give IFN-gamma. Molt 4 cells therefore provide a convenient source of human IFN-gamma and its mRNA for experimental purposes.

Bromodeoxyuridine↗
PubMed1981

Oligonucleotide fingerprinting of the RNA of different strains of infectious bronchitis virus.

11 distinct oligonucleotide fingerprints were obtained in studies of the RNA of 13 isolates of IBV. Different serotypes had distinct fingerprints, but so did varieties within a serotype; allowing a greater degree of strain differentiation than was previously possible. Some conclusions can be drawn from the fingerprints concerning theories of origin and spread of IBV.

Coronaviridae↗
PubMed1981

Fate of secretory proteins trapped in oocytes of Xenopus laevis by disruption of the cytoskeleton or by imbalanced subunit synthesis.

The effects of imbalanced subunit synthesis, temperature, colchicine, and cytochalasin on the secretion from Xenopus laevis oocytes of a variety of avian and mammalian proteins were investigated; these proteins were encoded by microinjected messenger RNA. Cytochalasin and colchicine together severely reduced secretion in a temperature-independent manner, the exact reduction varying among the different proteins. In contrast cytochalasin alone had no effect, whereas colchicine alone caused a smaller, temperature-dependent reduction. The synthesis and subcellular compartmentation of these proteins were unaffected by the drug treatments; however, the proteins did not accumulate in the drug-treated oocytes but were degraded. The rate of degradation of each protein was similar to its rate of exocytosis from untreated oocytes. A similar result was obtained without recourse to drugs by studying the fate of immunoglobulin light chains trapped in oocytes by a deficiency in heavy chain synthesis. These results are discussed in terms of the disruptive effects, as revealed by electron microscopy, of the drug treatments on the cytoskeleton of the oocyte.

Animals↗
PubMed1981

Production and screening of cell hybrids producing a monoclonal antibody to human interferon-alpha.

Mice and rats were immunized with human lymphoblastoid interferon, a mixture of human leukocyte (interferon-alpha) and human fibroblast (interferon-beta) interferons, and their serum anti-interferon levels measured. Anti-interferon activity was detected in all animals, although the mouse sera had higher titers than the rat sera. The spleens of two mice were removed and used to prepare hybrid myelomas. Anti-interferon activity in tissue culture supernatants was measured using a direct neutralization assay and a clone (NK2) producing antibody to human interferon-alpha (leukocyte) was isolated. The anti-interferon activity of this monoclonal antibody was confirmed using a new indirect immunoprecipitation (IIP) assay, which shows some advantages over the direct neutralization assay. The antibody did not neutralize human interferon-beta (fibroblast) or mouse interferon.

Animals↗
PubMed1981

Polypeptides of infectious bronchitis virus. I. Polypeptides of the virion.

Infectious bronchitis virus (IBV), strain Beaudette, grown in cultured cells contained five structural proteins with apparent mol. wt. of 170 000 (p170), 94 000 (gp94), 50 000 (pp50) 30 000 (gp30) and 26 000 (p26). Both gp94 and gp30 are glycopeptides since they were labelled with [3H]glucosamine. The only phosphorylated polypeptide was pp50, and both it and gp94 were occasionally resolved into two bands. Two other polypeptides with mol. wt. of 28 000 (p28) and 14 000 (p14) were sometimes associated with the virus. In egg-grown virus two additional proteins were found with mol. wt. of 110 000 (p110) and 75 000 (gp75). The cell protein, actin, was also found in highly purified IBV virions. Different serotypes of either tissue culture-grown or egg-grown virus showed one of the two distinct polypeptide patterns of IBV described by Nagy & Lomniczi (1979) and Collins & Alexander (1980 a, b). Strain Beaudette gave a pattern characteristic of the M type, while strain Connecticut gave a pattern characteristic of the C type. The polypeptides present in Connecticut virus were p170, gp98, pp50, gp28 and p26. Thus, the differences between the two pattern involve the mobility of both the large (gp94/gp98) and small (gp30/gp28) glycopeptides..

Actins↗
PubMed1981

Low temperature treatment of Namalwa cells causes superproduction of interferon.

Interferon production in Namalwa cells, a human lymphoblastoid line, was enhanced by lowering the incubation temperature after induction. The optimum conditions for this effect were established. At the lower temperature interferon synthesis proceeded at a lower rate but continued for longer. Interferon mRNA was shown to be associated with the polysomes for longer after induction. Addition of drugs that inhibit transcription did not prevent the increased production of interferon. Thus, the increased production of interferon is due to the prolonged translation of interferon mRNA.

Cell Line↗
PubMed1981

The influence of topology and glycosylation on the fate of heterologous secretory proteins made in Xenopus oocytes.

Secretory proteins made in Xenopus laevis oocytes under the direction of heterologous messenger RNA are modified, topologically segregated and exported. Thus the oocyte may serve as a useful surrogate secretory system and we have studied some of the factors governing access to the export pathway. Unglycosylated chicken ovalbumin, synthesized and trapped in the cytosol, is not secreted but glycosylated ovalbumin, found sequestered within vesicles, is exported from oocytes. However, ovalbumin, which is transferred across the endoplasmic reticulum in the presence of tunicamycin and which is indistinguishable by immunoprecipitation, by two-dimensional gel electrophoresis and by concanavalin-A--Sepharose binding from the cytosolic form, is still secreted. Guinea-pig milk proteins and human interferon are also exported from tunicamycin-treated frog cells. These observations demonstrate that access to the endoplasmic reticulum but not glycosylation is a mandatory intermediate step in secretion, and emphasize the advantages of the oocyte as a surrogate system for the study of the later events in the gene expression pathway.

Animals↗
PubMed1981

Oligonucleotide fingerprinting of ribonucleic acids of infectious bronchitis virus strains.

A total of 11 distinct oligonucleotide fingerprints were obtained in studies of the ribonucleic acids of 13 isolates of infectious bronchitis virus. Different serotypes had distinct fingerprints, but so did varieties within a serotype, allowing a greater degree of strain differentiation than was previously possible. Some conclusions can be drawn from the fingerprints concerning theories of origin and spread of infectious bronchitis virus.

Coronaviridae↗