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K Williamson

Publications and source records attributed to K Williamson.

At least 19 recordsLinked to original sources
PubMed1988

Solubilization and reconstitution of the formylmethionylleucylphenylalanine receptor coupled to guanine nucleotide regulatory protein.

We describe the solubilization, resolution, and reconstitution of the formylmethionylleucylphenylalanine (fMet-Leu-Phe) receptor and guanine nucleotide regulatory proteins (G-proteins). The receptor was solubilized with 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate. Guanine nucleotides decreased the number of high-affinity binding sites and accelerated the rate of dissociation of the receptor-ligand complex, suggesting that the solubilized receptor remained coupled to endogenous G-proteins. The solubilized receptor was resolved from endogenous G-proteins by fractionation on a wheat germ agglutinin (WGA)-Sepharose 4B column. High-affinity [3H]fMet-Leu-Phe binding to the WGA-purified receptor was diminished and exhibited reduced guanine nucleotide sensitivity. High-affinity [3H]fMet-Leu-Phe binding and guanine nucleotide sensitivity were reconstituted upon the addition of purified brain G-proteins. Similar results were obtained when the receptor was reconstituted with brain G-proteins into phospholipid vesicles by gel filtration chromatography. In addition, we also demonstrated fMet-Leu-Phe-dependent GTP hydrolysis in the reconstituted vesicles. The results of this work indicate that coupling of the fMet-Leu-Phe receptor to G-proteins converts the receptor to a high-affinity binding state and that agonist produces activation of G-proteins. The resolution and functional reconstitution of this receptor should provide an important step toward the elucidation of the molecular mechanism of the fMet-Leu-Phe transduction system in neutrophils.

Adenine Nucleotides↗
PubMed1988

Effect of LHRH agonist, Zoladex, on ovarian histology.

In a phase I clinical trial Zoladex was used as first line hormonal therapy in premenopausal women with advanced breast cancer. Patients on progression of their disease underwent surgical oöphorectomy. The histology of ovaries from 23 women treated with Zoladex has been compared with the ovaries from 34 patients who, before the clinical trial of Zoladex, underwent surgical oöphorectomy as primary therapy. Both groups show similar follicular phase development. Only 13 per cent of the Zoladex group developed corpora lutea while 58 per cent showed evidence of luteinization in the primary oöphorectomy group (P less than 0.01). Non-neoplastic follicular cysts were seen more often in the ovaries of the Zoladex treated patients than in the primary oöphorectomy group (P less than 0.05). Zoladex appears to arrest not folliculogenesis but follicular maturation with inhibition of ovulation, the follicles subsequently undergoing atresia with follicular cyst formation.

Breast Neoplasms↗
PubMed1987

A urine inhibitor of interleukin 1 activity that blocks ligand binding.

Urine from febrile patients was found to contain a novel inhibitor of interleukin 1 (IL-1) bioactivity that blocked the specific binding of radioiodinated IL-1 to its receptor in a dose-dependent fashion. Strong inhibition of IL-1 binding was still obtained when cells were preincubated with the inhibitor and washed, thus suggesting that the inhibitor binds to a surface structure (possibly the IL-1 receptor itself). The inhibitor was distinct from IL-1 as determined by both physical parameters (size and antigenicity) and receptor-binding characteristics (apparent affinity and dissociation rate). These data provide evidence for a physiologic regulator of IL-1 activity that functions in vivo via direct interference with ligand binding.

Animals↗
PubMed1987

A urine inhibitor of interleukin 1 activity affects both interleukin 1 alpha and 1 beta but not tumor necrosis factor alpha.

Urine from monocytic leukemia and other febrile patients contains an inhibitor of interleukin 1 (IL-1), as measured by prostaglandin E2 and collagenase production by human fibroblasts and synovial cells. With the use of recombinant IL-1, the IL-1 inhibitor was partially purified by using ammonium sulfate precipitation, anion-exchange, and gel filtration chromatographies. IL-1 inhibitory activity elutes with an 18,000 to 25,000 apparent molecular size. The same fractions also inhibit IL-1 assayed by the proliferation of murine thymocytes and human fibroblasts. Both forms of human recombinant IL-1, IL-1 alpha and IL-1 beta, which show only 26% homology, but nevertheless bind to the same receptor, are affected by this natural inhibitor to the same extent. In contrast, human recombinant tumor necrosis factor, which shares some of the biologic activities of IL-1, is not inhibited by the urinary IL-1 inhibitor. This study shows that the various biologic activities of both forms of human recombinant IL-1 are inhibited by a partially purified natural urine-derived factor.

Cell Division↗
PubMed1986

Purification and characterization of human interleukin-1 beta expressed in recombinant Escherichia coli.

The high-level expression of human interleukin-1 beta in Escherichia coli is described. The protein contributes about 12% of the total cell protein and is associated with the soluble cytoplasmic fraction of the cell. A method for the purification of the protein is given which is based on anion- and cation-exchange chromatographies. The isolated protein, shown to be homogeneous by several analytical methods, has been characterized by amino acid analysis, N- and C-terminal sequence analysis and analytical centrifugation. The protein is biologically active as demonstrated by two different in vitro assays, namely, the mononuclear cell factor (IL-1/MCF) assay and lymphocyte activating factor (IL-1/LAF) assay. The specific activities determined with the IL-1/MCF and IL-1/LAF assays, are 2 X 10(7) and 4 X 10(7) units mg-1, respectively.

Amino Acid Sequence↗
PubMed1986

Protein C antigen deficiency and warfarin necrosis.

Recent reports have suggested a correlation between congenital protein C deficiency and tissue necrosis complicating oral anticoagulants (warfarin necrosis). The authors studied blood samples of 13 patients, obtained two weeks to more than six months after warfarin necrosis. Protein C antigen levels were assayed by an enzyme-linked immunosorbent assay method (Diagnostica Stago, France). Factors II, VII, IX, and X were assayed by functional methods, and IX and X additionally by immunologic methods. The results show that 11 of 13 patients with a history of tissue necrosis had low protein C levels, ranging from 23 to 69%, with the normal range being 70-140%. These results confirm that low protein C antigen levels are implicated in the pathogenesis of warfarin necrosis.

Administration, Oral↗
PubMed1986

Prostaglandin E2 and collagenase production by fibroblasts and synovial cells is regulated by urine-derived human interleukin 1 and inhibitor(s).

Interleukin 1 (IL-1) possesses multiple biological activities that may be blocked selectively by different inhibitors. Some known inhibitors block the lymphocyte activating factor (LAF/IL-1) but not the mononuclear cell factor (MCF/IL-1) measured by its capacity to stimulate prostaglandin E2 (PGE2) and collagenase production. The presence of IL-1 in vivo may be difficult to detect due to the presence of inhibitor(s) and the level of the inhibitor(s) may vary depending upon pathological conditions. We have found that urine from three patients with monocytic leukemia (M5) contained high levels of inhibitor(s) of MCF/IL-1, whereas urine of normal subjects did not contain significant amounts. Urine from two patients with other blood neoplasic diseases also contained little inhibitory activity. The MCF/IL-1 inhibitor(s), which also acts on human recombinant IL-1 beta, is approximately 25-35 kD, is not retained on concanavalin A-Sepharose column and can be partially destroyed with urea and boiling. At this stage of the purification the fraction containing the MCF/IL-1 inhibitor(s) also inhibits the LAF/IL-1 assay. However, this inhibitor(s) is probably distinct from other inhibitors already described.

Adult↗
PubMed1985

Studies on the antithrombotic effects and pharmacokinetics of heparin fractions and fragments.

The pharmacokinetics of heparin differ markedly from those of its fractions both in man and in experimental animal models. The route of administration determines the relative availability of different molecular species that exert the anti-Xa, anti-IIa, fibrinopeptide A generation inhibiting actions and the release of tissue plasminogen activator-like activity from the endothelial cell lining. The bioavailability of heparin fractions has proved to be much greater than heparin after subcutaneous or intraperitoneal administration. Most of the low molecular weight heparin fractions exhibit sustained antiprotease and antithrombotic actions. The pharmacokinetics of the specific anti-IIa and anti-Xa actions of heparin and its fractions is dependent on the molecular composition of these agents. Even if the fractions are standardized for identical potencies by the in vitro assays, the elimination rate of anti-Xa and anti-IIa actions are significantly different for each fraction. The antithrombotic actions of heparin and its fractions also vary widely in the rabbit stasis thrombosis model. Different fractions show variable antithrombotic actions against defined thrombogenic challenges. Moreover, selection and potency of a thrombogenic agent is of crucial importance in these studies. The primate (Macaca mulatta) model offers a useful preclinical model for the pharmacologic evaluation of the low molecular heparin fractions. Since the coagulation system and heparinizability index of this model approximate a human response, the data may be used to reflect therapeutic and prophylactic responses, as well as to assess toxic effects, such as bleeding.

Animals↗