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At least 145 records · Page 8Linked to original sources

Serodiagnosis of acute hepatitis B virus infection by a modified competitive binding radioimmunoassay.

Using the Staphylococcus aureus absorption method, we have modified a commercial radioimmunoassay kit for the determination of total antibody to hepatitis B core antigen so that we can now determine the predominant globulin species of that antibody. One-hundred percent of acute hepatitis B sera had a predominance of immunoglobulin M antibody to hepatitis B core antigen, whereas immunoglobulin G antibody to hepatitis B core antigen was predominant in 98.2% of chronic hepatitis B surface antigen carriers. With this test and the commercially available tests for immunoglobulin M anti-hepatitis A virus, one can now reasonably differentiate acute hepatitis B from non A/non B hepatitis in a chronic hepatitis B surface antigen carrier.

Acute Disease↗

Inhibition of phorbol ester-induced cellular adhesion by competitive binding of NF-kappa B in vivo.

Adhesive interactions between cells are essential for the organization and function of differentiated tissues and organs and are mediated by inducible cell surface glycoproteins. In normal tissues, cell adhesion molecules contribute to immune regulation, inflammation, and embryogenesis. Additionally, they play an important role in a variety of pathogenic processes. Cell adhesion molecule expression can be induced by stimuli known to activate NF-kappa B, a ubiquitous transcription factor found in a variety of cell types. To investigate the role of NF-kappa B in cell adhesion molecule expression, we treated HL-60 cells with a double-stranded oligonucleotide which specifically inhibits NF-kappa B-mediated transcription. This treatment resulted in the inhibition of phorbol 12-myristate 13-acetate (PMA)-induced cellular adhesion, morphological changes, and the expression of leukocyte integrin CD11b. In a similar fashion, expression of intercellular adhesion molecule 1 on human endothelial cells induced by PMA was specifically inhibited by the NF-kappa B antagonist. We suggest that NF-kappa B activation is a necessary event for the PMA-induced differentiation of HL-60 cells and the expression of certain activation is a necessary event for the PMA-induced differentiation of HL-60 cells and the expression of certain adhesion molecules. Furthermore, the inhibition of transcription factor functions by this generally applicable mechanism can be used to define their role in cellular differentiation and function.

Base Sequence↗

Model of competitive binding of vascular endothelial growth factor and placental growth factor to VEGF receptors on endothelial cells.

Placental growth factor (PlGF) competes with vascular endothelial growth factor (VEGF) for binding to VEGF receptor (VEGFR)-1 but does not bind VEGFR2. Experiments show that PlGF can augment the response to VEGF in pathological angiogenesis and in models of endothelial cell survival, migration, and proliferation. This synergy has been hypothesized to be due to a combination of the following: signaling by PlGF through VEGFR1 and displacement of VEGF from VEGFR1 to VEGFR2 by PlGF, causing increased signaling through VEGFR2. In this study, the relative contribution of PlGF-induced VEGF displacement to the synergy is quantified using a mathematical model of ligand-receptor binding to examine the effect on ligand-receptor complex formation of VEGF and PlGF acting together. Parameters specific to the VEGF-PlGF system are used based on existing data. The model is used to simulate in silico a specific in vitro experiment in which VEGF-PlGF synergy is observed. We show that, whereas a significant change in the formation of endothelial surface growth factor-VEGFR1 complexes is predicted in the presence of PlGF, the increase in the number of VEGFR2-containing signaling complexes is less significant; these results were shown to be robust to significant variation in the kinetic parameters of the model. Synergistic effects observed in that experiment thus appear unlikely to be due to VEGF displacement but to a shift from VEGF-VEGFR1 to PlGF-VEGFR1 complexes and an increase in total VEGFR1 complexes. These results suggest that VEGFR1 signaling can be functional in adult-derived endothelial cells.

Animals↗

[Competitive binding of some alkyl p-hydroxybenzoates to human estrogen receptor alpha and beta].

Alkyl p-hydroxybenzoates such as isobutyl p-hydroxybenzoate (PHBA-iBu), butyl p-hydroxybenzoate (PHBA-nBu), isopropyl p-hydroxybenzoate (PHBA-iPr), propyl p-hydroxybenzoate (PHBA-nPr), ethyl p-hydroxybenzoate (PHBA-Et), and methyl p-hydroxybenzoate (PHBA-Me) are widely used as preservatives, stabilizers and antiseptics for medical supplies, cosmetics, foodstuffs etc. We determined the binding affinity of alkyl p-hydroxybenzoates to human estrogen receptor alpha (ER alpha) and beta (ER beta) by non-RI receptor binding assays. PHBA-iBu had a high binding affinity for ER alpha (IC50: 6.0 x 10(-6) M, the relative binding affinity (RBA): 0.267) and ER beta (IC50: 5.0 x 10(-6) M, RBA: 0.340). These IC50 values and RBA were almost the same as those of bisphenol A. The ranking of the estrogenic potency of alkyl p-hydroxybenzoates for both ERs is different; that is, PHBA-iBu > PHBA-nBu[symbol: see text]PHBA-iPr[symbol: see text]PHBA-nPr > PHBA-Et >> PHBA-Me. Alkyl p-hydroxybenzoates bound with equal relative affinity to both ER alpha and beta proteins. Alkyl p-hydroxybenzoate having a long alkyl side-chain showed a high affinity for ER alpha and beta. These findings suggest that p-hydroxybenzoates may be endocrine disruptors.

Binding, Competitive↗

Competitive binding of postsynaptic density 95 and Ca2+-calmodulin dependent protein kinase II to N-methyl-D-aspartate receptor subunit 2B in rat brain.

AIM: To investigate the interactions among postsynaptic density 95 (PSD-95), Ca2+-calmodulin dependent protein kinase IIalpha (CaMKIIalpha), and N-methyl-D-aspartate receptor subunit 2B (NR2B) during ischemia and reperfusion in hippocampus of rats. METHODS: Brain ischemia was induced by four-vessel occlusion procedure in rats. Immunoprecipitation and immunoblotting were performed to study the interactions and phosphorylation of proteins. The association-dissociation of PSD-95 and CaMKIIalpha to and from N-methyl-D-aspartate (NMDA) receptor induced by ischemia and reperfusion and the effects of 1-[N,O-bis-(5-isoquinolinesulfonyl)-N-methyl-L-tyrosyl]-4-phenyl-piperazine (KN-62, a selective inhibitor of CaMKII) on these protein interactions were investigated. Coimmunoprecipitation and immunoblotting were performed for the studies of interactions among proteins. RESULTS: The alternations of the binding level of PSD-95 and CaMKIIalpha to NR2B during ischemia and reperfusion demonstrated the negative correlation to each other. Pre-administration of KN62 through both cerebral ventricles inhibited the 10 min ischemia-induced increase of the binding of PSD-95 to NR2B and, on the contrary, promoted the binding of CaMKIIalpha to NR2B. CONCLUSION: PSD-95 competes with CaMKII to bind to NR2B during ischemia and reperfusion in rat hippocampus.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗