ON THE SOLVABILITY OF THE NULLATOR-NORATOR PAIRS NETWORK

The paper deals with the unique solvability of a nullator-norator pairs network consisting of RLC elements and source generators. After defining the kernel of a network the normaL inverse normal, distinguished and reactance trees of the network graph are introduced. Setting out from [6] necessary and sufficient conditions are given for the unique solvability. A topological formula is introduced from which many sufficient conditions of the unique solvability can be obtained as algebraic equations between the parameters of the RLC network elements. The results of the paper are illustrated by examples. Finally. a block scheme is presented for the examination of the unique solvability by computer technique

Synthesis and binding characteristics of two sulfhydryl-reactive probes for vasopressin receptors

AbstractThe present study describes the synthesis and receptor binding affinities of the sulfhydryl-reactive vasopressin analogs deamino[Dab(N8-N-maleoyl-β-alanin e)4]AVP (1a) and deamino[Lys(N8-N-maleoyl-β-alanine)8VP (2a). The analogs were obtained by introducing the sulfhydryl-reactive maleoyl-β-alanyl group at the δ-amino group of Dab4 in deamino[Dab4]IAVP (1) and at the ε-amino group of Lys8 in deamino[Lys8]VP (2), which were synthesized by the solid-phase method. Furthermore, the analog modified at Dab4 was prepared as tritium labeled compound (1b) after catalytic iodine tritium exchange at Tyr2 in deamino[Dab4]AVP. The sulfhydryl-reactive vasopressin analogs retained high binding affinity for the V2 vasopressin receptor in membranes derived from bovine kidney inner medulla. Apparent dissociation constants Kd of 45 nM (compound 1a) and 15 nM (compound 2a) were determined. Incubation of the ligand receptor complexes at pH 5.5 resulted in dissociation of the sulfhydryl-reactive vasopressin analogs from the V2 receptor. No indications of a covalent reaction between analogs 1a, 2a and 1b and sulfhydryl groups in or close to the hormone binding site of the V2 receptor were found