The novel pyridoxal-5'-phosphate derivative PPNDS potently antagonizes activation of P2X(1) receptors.

Pyridoxal-5'-phosphate-6-(2'-naphthylazo-6'-nitro-4',8'-disulfonat e) (PPNDS) potently antagonized P2X(1) receptor-mediated responses in rat vas deferens (pK(B)=7.43) and Xenopus laevis oocytes (pIC(50)=7. 84). It showed lower (up to 20,000-fold) inhibitory potency on ecto-nucleotidase in Xenopus oocytes and on P2Y(1) receptors in guinea-pig ileum (pA(2)=6.13). PPNDS did not interact with alpha(1A)-adrenoceptors, adenosine A(1) and A(2B), histamine H(1) and muscarinic M(3) receptors. Thus, PPNDS is a novel, specific P2 receptor antagonist and represents the pyridoxal-5'-phosphate derivative with the highest potency at P2X(1) receptors.

Novel ligands for P2 receptor subtypes in innervated tissues.

Among suramin analogues, the properties of P2 receptor subtype blockade and ecto-nucleotidase inhibition appear to be controlled by different structural parameters (Fig. 1 and 2, Table 1; Van Rhee et al., 1994; Beukers et al., 1995; Bültmann et al., 1996; Damer et al., 1998a, 1998b; and this study): the molecular size of the compounds, the position of the sulfonic acid residues in the naphthalene rings, the substitution pattern of the benzoyl moieties and the 3'- or 4'-aminobenzoyl-linkages of the phenyl rings "1" and "2". As a result, compounds with different receptor selectivity profiles were obtained. A maximum in potency at and selectivity for P2X1 receptors is reached in NF279, which is a specific P2 receptor antagonist and the compound with the highest P2X1 vs. P2Y receptor and ecto-nucleotidase selectivity presently available.

NF279: a novel potent and selective antagonist of P2X receptor-mediated responses.

8,8'-(Carbonylbis(imino-4, 1 -phenylenecarbonylimino-4,1-phenylenecarbonylimino))bis(1,3, 5-naphthalenetrisulfonic acid) (NF279) antagonized P2X receptor-mediated contractions in rat vas deferens, evoked by alpha,beta-methylene ATP (10 microM; pIC50=5.71) without affecting responses mediated via alpha1A-adrenoceptors, adenosine A1 and A2B receptors, histamine H1, muscarinic M3 and nicotinic receptors. The low inhibitory potency of NF279 on P2Y receptors in guinea-pig taenia coli (pA2=4.10) and at ecto-nucleotidases in folliculated Xenopus laevis oocytes (IC50 > 100 microM) indicates that NF279 is a novel specific and selective P2X receptor antagonist.

Effects on traction of outsole composition and hardnesses of basketball shoes and three types of playing surfaces.

The purposes of this investigation were to determine the effects of outsole composition and hardness, playing surfaces and player weight on the dynamic torque, traction forces and static drag developed at the shoe-surface interface. Basketball shoes of polyurethane and elastomer outsoles, each of three different hardnesses, were tested on clean and dusty hardwood floor samples, and on a sample of an artificial gymnasium flooring. The tests were conducted using a laboratory apparatus which included a player leg assembly with simulation of two player weights. Dynamic torque, traction forces from side and rear impacts and static drag were measured at the shoe surface interface. The results indicated that in basketball the magnitude of the resistance forces and torques are influenced by the outsole material and outsole hardness of the shoes, the playing surface and player weights.

Torques developed by different types of shoes on various playing surfaces.

The purpose of this investigation was to determine the effects of shoe type, playing surface, weight supported and stance position upon the torques developed at the shoe-turf interface. The study was predicated upon the assumption that many knee injuries are torque-related and due to foot fixation, either by rigid cleating or by excessive traction between the shoe and playing surface. A laboratory apparatus was designed to measure the torque developed by various shoe-surface combinations. Under investigation were 11 shoe types, three artificial surfaces and natural grass, two player weights, and two player foot-stance positions. Torque data were gathered using impact loading, with an impact energy that is probably often experienced under competitive playing conditions. Resulting data indexed the shoes according to the mean torques developed on each of the playing surfaces, and comparisons of torque data with field studies by other researchers suggested which shoe-surface combinations might be the most potentially hazardous.