δ-opioid receptor antagonists exhibit properties of partial δ-receptor agonists in isolated perfused heart

Perfusion of the isolated intact rat heart with Krebs—Henseleit solution containing agonists ((-)-TAN-67, DPDPE, and dalargin) or antagonists of -opioid receptors (naltrindole, TIPP[], and ICI 174,864) in a final concentration of 0.1 mg/liter was followed by a decrease in the heart rate, end-diastolic pressure, contraction rate, relaxation rate, and left ventricular developed pressure. Perfusion with a solution containing the -opioid receptor agonist DPDPE or -antagonists naltrindole, TIPP[], and ICI 174,864 before modeling of global ischemia increased the severity of reperfusion-induced contractile dysfunction in the myocardium. Our results suggest that -opioid receptor antagonists in vitro exhibit properties of partial - receptor agonists.Translated from Byulleten Eksperimentalnoi Biologii i Meditsiny, Vol. 138, No. 10, pp. 424–427, October, 2004     

Inhibitory effects on HLA-DR1-specific T-cell activation by influenza virus haemagglutinin-derived peptides

Collagen (CII) 263-272 peptide, an autoantigen in rheumatoid arthritis, is a specific human leukocyte antigen (HLA)-DR1/4-binding peptide recognized by T-cell receptors (TCR). The affinity of influenza virus haemagglutinin (HA) 306-318 peptide for the antigen-binding groove of HLA-DR1/4 molecules is higher than that of CII263-272. The HLA-DR1/4-binding residues of HA306-318 are located in the region 308-317. Altered HA308-317 peptides with substitutions of TCR-contact residues may inhibit HLA-DR1/4-specific T-cell activation by blocking the antigen-binding site of HLA-DR1/4 molecules. To evaluate the role of altered HA308-317 peptides in HLA-DR1-restricted T-cell activation, we synthesized three altered HA308-317 peptides. The specific binding of altered HA308-317 peptides to HLA-DR1 molecules was examined using flow cytometry. Effects of altered HA308-317 peptides on HLA-DR1-specific T-cell hybridoma were studied by measuring T-cell proliferation and surface expression of CD69 or CD25. The results showed that altered HA308-317 peptides were able to bind to HLA-DR1 molecules and competed with CII263-272 or wildtype HA308-317 peptide. Compared with wildtype CII263-272 or HA308-317, altered HA308-317 peptides did not stimulate significant T-cell proliferation and CD69 or CD25 expression. Furthermore, the altered HA308-317 peptides inhibited HLA-DR1-specific T-cell activation induced by CII263-272 or wildtype HA308-317 peptide, which may suggest an effective therapeutic strategy in inhibition of HLA-DR1-specific T-cell responses in autoimmunity.     

IgG-and C3-dependent adhesion of neutrophils in systems with allogeneic and xenogeneic ligands

S. M. Kirov Medical Institute. Nizhnii Novgorod (Presented by Academician of the Academy of Medical Sciences of the USSR K. P. Kashkin). Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 112, No. 10, pp. 403–404, October, 1991.     

Effect of ligands of opiate receptors on morphofunctional state of the sympathoadrenal system and electrical stability of the heart in acute cold exposure

Acute cold exposure (−20°C, 4 h) induces a transient decrease in the ventricular fibrillation threshold without morphological and radionuclide signs of irreversible damage to cardiomyocytes. The agonist of μ-receptors DAGO, which reduces adrenoreactivity of the myocardium, prevents the decrease in the ventricular fibrillation threshold induced by acute cold exposure. Translated fromByulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 123, No. 2, pp. 154–157, February, 1997     

Herpes virus entry mediator synergizes with Toll-like receptor mediated neutrophil inflammatory responses

In microbial infections polymorphnuclear neutrophils (PMN) constitute a major part of the innate host defence, based upon their ability to rapidly accumulate in inflamed tissues and clear the site of infection from microbial pathogens by their potent effector mechanisms. The recently described transmembrane receptor herpes virus entry mediator (HVEM) is a member of the tumour necrosis factor receptor super family and is expressed on many haematopoietic cells, including T cells, B cells, natural killer cells, monocytes and PMN. Interaction of HVEM with the natural ligand LIGHT on T cells has a costimulatory effect, and increases the bactericidal activity of PMN. To further characterize the function of HVEM on PMN, we evaluated the effect of receptor ligation on human PMN effector functions using an agonistic monoclonal antibody. Here we demonstrate that activation of HVEM causes activation of neutrophil effector functions, including respiratory burst, degranulation and release of interleukin-8 in synergy with ligands for Toll-like receptors or GM-CSF. In addition, stimulation via HVEM enhanced neutrophil phagocytic activity of complement opsonized, but not of non-opsonized, particles. In conclusion, these results indicate a new, as yet unknown, participation of HVEM in the innate immune response and points to a new link between innate and adaptive immunity.     

Controlled/“Living” Radical Polymerization of Methyl Methacrylate Catalyzed by Cobalt Acetate

Using cobalt acetate as a catalyst, the controlled/“living” polymerization of MMA was carried out. PMMA with a predicted molecular weight and a low polydispersity was obtained. Using the obtained PMMA as a macroinitiator, a chain extension reaction was carried out. This increased the molecular weight of PMMA from 23 600 to 36 100, in good agreement with the predicted value, and the polydispersity index became lower . This indicated the “living” character of the polymerization. Bulk polymerization of styrene catalyzed by cobalt acetate using the obtained polystyrene as a macroinitiator yielded well‐defined PS‐b‐PMMA.

     

Dll3 is expressed in developing hair cells in the mammalian cochlea.

Notch mediates the process of lateral inhibition that controls the production of hair cells in the inner ear. Hair cells are known to express Notch ligands Dll1 and Jag2, which signal through Notch1 in adjacent supporting cells. However, recent genetic and pharmacological studies indicate that the level of Notch-mediated lateral inhibition is greater than can be accounted for by Dll1 and Jag2. Here, we report that another Notch ligand, Dll3, is expressed in developing hair cells, in a pattern that overlaps that of Dll1 and Jag2. We analyzed the cochleae of Dll3(pu) mutant mice, but did not detect any abnormalities. However, earlier studies have demonstrated that there is functional redundancy among Notch ligands in cochlear development and loss of one ligand can be at least partially compensated for by another. Thus Dll3 may play a role in lateral inhibition similar to that of Dll1 and Jag2.     

Phenotypic characteristics of lewis lung carcinoma cells

We studied adhesive properties and physiological activity in vivo of cells from Lewis lung carcinoma and its metastases. These cells differed in tumorogenic activity and metastatic potential in the syngeneic system. In vivo non-metastasizing cells are characterized by a lower content of surface lectins to tetrasaccharides SiaLe^x [Neu5Ac2-3Gal1-4(Fuc1-3) GlcNAc] and SiaLe^a [Neu5Ac2-3Gal1-3(Fuc1-4)GlcNAc] and trisaccharide HSO₃Le^x [HSO₃2-3Gal1-4(Fuc1-3)GlcNAc] compared to cells forming metastases in the syngeneic system. Metastatic cells with low tumorogenic activity weakly expressed lectins to disaccharide ligands 6-SiaLac [Neu5Ac2-6Gal1-4Glc], 6-HSO₃LacNAc, and A-di [GalNAc 1-3Gal] and trisaccharides H-type 1 [Fuc1-2Gal1-3GlcNAc and Le^x [Fuc1-3(Gal 1-4)GlcNAc] compared to cells that initiated tumor formation in the syngeneic system (similarly to transplanted tumors). We hypothesized that cell receptors to these carbohydrate determinates are involved in the development and growth of primary tumors, while lectins to SiaLe^x, SiaLe^a, and HSO₃Le^x play a role in the progress of tumor process and metastasizing.     

Peptide analogues of a T-cell epitope of ricin toxin A-chain prevent agonist-mediated human T-cell response

The clinical efficacy of immunotoxins (IT) containing ricin toxin A-chain (RTA) can be drastically reduced by anti-toxin-neutralizing antibodies developed by patients. Strategies aimed at epitope-specific modulation of the immune response must be therefore set up to broaden the clinical applicability of RTA-based IT. Prevention or reduction of humoral immune responses against RTA could be achieved by peptide-based down-modulating strategies. Peptide analogues were investigated as candidate antagonist altered peptide ligands (APL) considering the sequence of a previously identified dominant T-cell epitope of RTA (i.e. I175-E185) presented in the context of the HLA-DRB1*03011 allele. Alanine-substituted peptides provided information on the role of individual residues of the wild-type peptide and allowed to identify one antagonist APL corresponding to the double-mutant peptide E177A/A178D. The analogue E177A/A178D not only prevented the agonist from stimulating anti-RTA human T-cell clones but also failed to induce down-regulation of surface-expressed TCR, thus suggesting its possible use for in vivo immune modulation of anti-RTA responses.