Mechanism of the clinical effects of UV-irradiated blood: Stimulation of DNA synthesis by human cells in culture

Bulletin of Experimental Biology and Medicine -     

Preparation of monoclonal antibodies against human thyrotropin suitable for diagnostic systems and their use in clinical practice

Original methods are presented for immunizing mice with preparations of human thyrotropic and for testing primary clones of producer hybridomas. Twelve monoclonal antibodies specific to six different regions of the antigen are obtained. A test system for enzyme immunoassay is developed on the basis of two antibodies, providing for detection of hypo- and hyperthyreoidism in clinical practice. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 118, N ^o 10, pp. 433–435, October, 1994 Presented by D. S. Sarkisov, Member of the Russian Academy of Medical Sciences     

Voltage-dependent block of native AMPA receptor channels by dicationic compounds

1. The kinetics of open channel block of GluR2-containing and GluR2-lacking AMPA receptors (AMPAR) by dicationic compounds (IEM-1460, IEM-1754, and IEM-1925) have been studied in rat hippocampal neurones using whole-cell patch clamp recording and concentration-jump techniques. Neurones were isolated from hippocampal slices by vibrodissociation. 2. The dicationic compounds were approximately 100 - 200 times more potent as blockers of GluR2-lacking AMPAR than as blockers of GluR2-containing AMPAR. The subunit specificity of channel block is determined by the blocking rate constant of a dicationic compound, whereas differences in unblocking rate constants account for differences in potency. 3. Hyperpolarization may decrease the block produced by IEM-1460 and IEM-1754 block due to the voltage-dependence of the unblocking rate constants for these compounds. This suggests that dicationic compounds permeate the AMPAR channel at negative membrane potentials. The effect was particularly apparent for GluR2-lacking AMPAR. These findings indicate that the presence of GluR2-subunit(s) in AMPAR hinders the binding of the cationic compounds and their permeation through the channel. 4. The most potent compound tested was IEM-1925. The presence of a phenylcyclohexyl moiety instead of an adamantane moiety, as in IEM-1460 and IEM1754, is probably responsible for the higher potency of IEM-1925. Dicationic compounds are important not only as pharmacological tools, but also as templates for the synthesis of new selective AMPAR blockers which may be potential therapeutic agents.     

Activation of immunosorption properties of blood by UV irradiation in therapeutic doses

Institute of Cytology, Academy of Sciences of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR Yu. A. Vladimirov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 108, No. 12, pp. 689–691, December, 1989.     

CTLA-4 is required for the induction of high dose oral tolerance

Mucosal and systemic administrations of high dose antigens induce long- lasting peripheral T cell tolerance. We and others have shown that high dose peripheral T cell tolerance is mediated by anergy or deletion and is preceded by T cell activation. Co-stimulatory molecules B7-1 (CD80)/B7-2 (CD86) and their counter-receptors CD28/CTLA-4 play pivotal roles in T cell activation and immune regulation. In the present study, we examined the roles of the B7 co-stimulation pathway in the generation of high dose peripheral T cell tolerance. We found that blocking B7:CD28/CTLA-4 interaction at the time of tolerance induction partially prevented T cell tolerance, whereas selective blockade of B7:CTLA-4 interaction completely abrogated peripheral T cell tolerance induced by either oral or i.p. antigens. These results suggest that CTLA-4-mediated feedback regulation plays a crucial role in the induction of high dose peripheral T cell tolerance.      

Cellular control of nitric oxide synthase expression and activity in rat cardiomyocytes

Potential ortho- and pathophysiological roles for nitric oxide synthases (NOS) in cardiac functions have been and are continuing to be described. However, cellular signaling mechanisms controlling nitric oxide (NO) production in the heart remain obscure. The aim of this study was to investigate signaling mechanisms involved in regulation of NOS expression and NO generation in cardiomyocytes. Using immunocytochemical methods in conjunction with western blotting, we have found that cultured neonatal rat cardiomyocytes express constitutively all three NOS isoforms targeted predominantly to the particulate component of cardiomyocytes - mitochondria and along contractile fibers, as well as along plasma membrane including T-tubules. Biochemical assay of NO generation has shown that exposure of cultured neonatal rat cardiac cells to isoproterenol (beta-adrenergic stimulation), iloprost [stable prostaglandin I(2) (PGI(2)) analogue], as well as inflammatory cytokines and dibutyryl adenosine-3',5'-monophosphate (db-cAMP), resulted in a marked up-regulation of NOS expression by cardiomyocytes. In db-cAMP-stimulated cells, inhibition of protein kinase A (PKA) and protein kinase C (PKC) reduced immunolabeling of NOS and concomitantly lowered NO production. Taken together, these data point to an involvement of beta-adrenergic mechanisms, cytokine and PGI(2) receptors, adenylyl cyclase, PKA, and PKC in the control of NO generation and expression of NOS in rat cardiomyocytes.     

Structural Characteristics of Ionotropic Glutamate Receptors as Identified by Channel Blockade

The channels of four types of ionotropic glutamate receptor (NMDA receptors and Ca-permeable AMPA receptors of rat brain neurons, and cation-selective receptors from mollusk neurons and insect postsynaptic muscle membranes) and two subtypes of nicotinic cholinoreceptor (from frog neuromuscular junctions and cat sympathetic ganglia) were studied. The structural characteristics of channels determining their susceptibility to blockade by organic mono- and dications were identified. These studies used homologous series of adamantane and phenylcyclohexyl derivatives. These experiments showed that the receptors studied here could be divided into two groups. The first group included the AMPA receptor and the mollusk and insect receptors. These were characterized by the lack of effect on the part of monocations and a strong relationship between the activity of dications and the distance between nitrogen atoms. The second group included the NMDA receptor and both subtypes of the nicotinic cholinoreceptor (muscular and neuronal). Here, conversely, the activity of monocations and dications, regardless of their lengths, were essentially identical. A model for the binding sites of blockers in channels is proposed, which takes these observations into account.