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M Sharon

Publications and source records attributed to M Sharon.

35 records · Page 2Linked to original sources
PubMed1988

Possible association between IL-2 receptors and class I HLA molecules on T cells.

In the process of evaluating murine hybridomas for an antibody to the beta-subunit of the IL-2R (p70) we identified an antibody that immunoprecipitated a 55- to 57-kDa complex from cross-linked lysates. We demonstrate that this complex is composed of IL-2 (15.5 kDa) cross-linked to the H chain of HLA class I (40 to 42 kDa), suggesting a molecular interaction between HLA class I molecules and IL-2R. Although the exact role of this association remains to be determined, the specific cross-linking of IL-2 to HLA class I Ag is intriguing in view of published claims for a role of HLA class I in OKT3-induced lymphocyte proliferation and in NK cell lytic activity.

Animals↗
PubMed1988

The human interleukin 2 receptor beta chain (p70). Direct identification, partial purification, and patterns of expression on peripheral blood mononuclear cells.

IL-2 binds to high- and low-affinity receptors on activated T cells. The high-affinity receptor was hypothesized to consist of the noncovalent association between the alpha chain (IL-2-R-alpha, p55) and a beta chain (IL-2-R-beta, p70), whereas the low-affinity receptor consists of p55 without p70. We now directly identify p70 as a 65-77-kD glycoprotein doublet. Preparative quantities of the IL-2/p70 complex have been isolated. Further, we demonstrate that p70 is the principal IL-2 binding protein on both resting CD4+ and CD8+ T cells and that both p70 and p55 can be induced on normal B cells and monocytes.

Antigens, Surface↗
PubMed1987

The IL-2 receptor beta chain (p70): role in mediating signals for LAK, NK, and proliferative activities.

Interleukin-2 (IL-2) induces cytolytic activity and proliferation of human blood lymphocytes. Yet, prior to activation, these cells do not express IL-2 receptors recognized by monoclonal antibodies to the Tac antigen. A novel glycoprotein (IL-2R beta), identified on several lymphocytoid cell lines, has the ability to bind IL-2 alone and to associate with Tac antigen (IL-2R alpha) to form high-affinity IL-2 receptors. It is now reported that IL-2R beta is expressed on both circulating T lymphocytes and large granular lymphocytes in quantities approximately proportional to their responsiveness to IL-2. Studies of the responses of these cells to IL-2 suggest that IL-2R beta mediates the initial phase of induction of lymphokine activated killer (LAK), natural killer (NK), and proliferative activities. Subsequently, IL-2R alpha is induced and functional high-affinity IL-2 receptors are expressed.

Antibodies, Monoclonal↗
PubMed1987

Traumatic internal jugular vein cannulation.

A 63-year-old man with acute myocardial infarction complicated by atrioventricular block underwent an insertion of a temporary electrode for cardiac pacing. The posterior approach for right internal jugular vein cannulation was used. A 15-gauge needle was inserted under the sternocleidomastoid muscle aiming at the suprasternal notch with a 30-degree posterior angle of entry. An hour later the patient started to hiccup. The hiccups were resistant to drug therapy and to cessation of pacing. A chest radiograph revealed elevation of the right diaphragm and hematoma on the right side of the trachea, possibly compressing the right phrenic nerve on its route beneath the sternocleidomastoid muscle and the internal jugular vein. Within seven days the hiccups gradually ceased. Our case shows the advantages and complications of internal jugular vein cannulation.

Catheterization↗
PubMed1986

Novel interleukin-2 receptor subunit detected by cross-linking under high-affinity conditions.

Interleukin-2 (IL-2) binds to both high- and low-affinity classes of IL-2 receptors on activated T lymphocytes. Only the high-affinity receptors are involved in receptor-mediated endocytosis and normally transduce the mitogenic signals of IL-2; however, the structural features distinguishing the high- and low-affinity receptors are unknown. When 125I-labeled IL-2 was chemically cross-linked to activated human T lymphocytes, two major bands were identified. First, as predicted, a 68- to 72-kilodalton band, consisting of IL-2 (15.5 kilodaltons) cross-linked to the IL-2 receptor (55 kilodaltons), was observed. Second, an unpredicted 85- to 92-kilodalton moiety was detected. This band was not present when IL-2 was cross-linked to transfected C127 cells, which exclusively express low-affinity receptors. The data presented are most consistent with the existence of a 70- to 77-kilodalton glycoprotein subunit (p70) which, upon associating with the 55-kilodalton low-affinity receptor (p55), transforms it into a high-affinity site. It is proposed that p55 and p70 be referred to as the alpha and beta subunits, respectively, of the high-affinity IL-2 receptor.

Animals↗
PubMed1984

Equivalence between one step kinetics and Hill's equation.

One step kinetics between oxygen and haemoglobin are shown to be equivalent to the well-known Hill's equation. We have modified the one step kinetics while dealing with the mathematical modelling of simultaneous transport of oxygen and carbon-dioxide in the blood flowing through the pulmonary and the systemic capillaries. In the process, the Hill's equation has been modified showing an explicit dependence on PCO2. We have proposed comparatively simpler equations to represent Hb saturation with O2 and CO2 allowing for the interaction between the gases. It is shown that the oxygen dissociation curve, obtained from modified equations, fits in fairly well with the experimental data and shows realistic shift with PCO2. The results computed from our comparatively simpler equations based on physical laws, are in good agreement with those obtained from Kelman's empirical relations that are accepted in anaesthesia and respiratory physiology as providing very good matches to reality.

Biomedical Engineering↗
PubMed1980

The synthesis of folate-binding protein in lymphocytes during transformation.

The blast transformation of human lymphocytes exposed to phytohaemagglutinin was associated with an increase in the intracellular concentration of a folate-binding protein. The protein was measured by a radioimmunoassay and by immunofluorescent microscopy using an antiserum raised against purified folate-binding protein prepared from chronic myelogenous leukaemia cells. Because it has been previously shown that protein-bound folate cannot function as a cofactor or substrate, the synthesis of this binder during some phase of the replicative cycle may serve to modulate folate-dependent RNA and DNA synthesis by controlling the concentration of free folate.

Carrier Proteins↗
PubMedDate not supplied

Effect of mutant small, acid-soluble spore proteins containing cysteine or tryptophan on DNA properties in vivo and in vitro.

Two derivatives of the alpha/beta-type small acid-soluble spore protein (SASP) SspCwt have been constructed, each containing a residue potentially useful for physico-chemical analysis of protein-protein or protein-DNA interactions. In one mutant protein (SspCtrp) residue 27 (Met) was replaced by Trp; in the second (SspCcys) residue 48 (Asn) was replaced by Cys. Both mutant proteins were expressed in Bacillus subtilis spores at levels similar to those of SspCwt, and SspCcys and SspCtrp restored ultraviolet light (UV) resistance and plasmid negative supercoiling in spores lacking major alpha/beta-type SASP to levels similar to those restored by SspCwt. While the purified mutant proteins bound more weakly to DNA than SspCwt, all three had the same relative affinity for different DNAs, ie poly(dG).poly(dC) greater than poly(dG-dC).poly(dG-dC) greater than pUC19, and purified SspCcys and SspCtrp gave the same pattern of DNase protected bands with pUC19 as SspCwt. Binding of SspCcys or SspCtrp to poly(dG).poly(dC) in vitro also prevented the formation of cyclobutane type cytosine dimers upon UV irradiation, as does binding of SspCwt. These data indicate that the two mutant proteins are extremely similar to SspCwt in their interaction with DNA, and thus may be useful in probing SASP-SASP and SASP-DNA interactions directly by physical or chemical techniques. Indeed, binding of SspCtrp to poly(dG).poly(dC) resulted in a 2.5-fold enhancement of the proteins Trp fluorescence.

Amino Acid Sequence↗
PubMedDate not supplied

High-dose metronidazole: pharmacokinetics and bioavailability using an iv preparation and application of its use as a radiosensitizer.

As an extension of studies on the clinical use of nitroimidazoles as radiosensitizers, single-dose pharmacokinetic studies of iv metronidazole (500 mg/100-ml vials) were performed in eight consenting patients. Single doses of 0.5, 1.0, 1.5, and 2.0 g (0.29-1.21 g/m2) were administered iv by a zero-order infusion pump. Serial timed blood and urine samples were assayed for metronidazole and its two metabolites (acetic acid and ethoxy compounds) using a high-pressure liquid chromatographic assay. Open two-compartment kinetic characteristics of metronidazole were computed from simultaneous plasma infusion and urine excretion-rate equations using a nonlinear least-squares regression analysis program (NONLIN). Means of the four kinetic parameters were (h-1): k12, 1.18; k21, 0.86; k10, 0.22; and k'e, 0.46 x 10(-4). Means of the apparent volumes of distribution were (liters/kg): Vc, 0.41; VB, 1.02; and Vss, 0.75. The mean (+/- SD) for alpha-half-life was 1.2 +/- 1.3 hours, and that for beta-half-life was 9.8 +/- 5.9 hours. Seven of the eight patients received a second identical dose orally 1 week later, and the absolute bioavailability was estimated to approximate 100%. Unless the oral route is not feasible and if immediate high peak blood levels are not necessary, oral metronidazole is the preferred route of administration of metronidazole for its radiosensitizing effects.

Adult↗