5-hydroxytryptamine inhibits pressor responses to preganglionic sympathetic nerve stimulation in pithed rats

5-Hydroxytryptamine (5-HT) inhibits contractile responses to adrenergic nerve stimulation in several blood vessels and organs. We have now investigated the potential ability of 5-HT to inhibit the pressor responses caused by preganglionic sympathetic stimulation (T7-T9) in pithed rats. Sympathetic stimulation (0.03, 0.1, 0.3, 1 and 3 Hz) resulted in frequency-dependent increases in diastolic blood pressure; these effects were augmented after i.v. treatment with desipramine (50 micrograms/kg). During continuous infusions of 5-HT (1.8, 3.1, 5.6 and 10 micrograms/kg.min, i.v.), but not of saline, the pressor responses were dose-dependently inhibited in both control and desipramine-pretreated rats; this inhibitory effect of 5-HT was significantly more pronounced at lower frequencies of stimulation. In contrast, the above infusions of 5-HT did not inhibit the pressor responses induced by i.v. bolus injections of exogenous norepinephrine (up to 3 micrograms/kg). Taken together, the above findings suggest an operative 5-HT-induced prejunctional inhibition of sympathetic nerve activity on the systemic vasculature in vivo.     

Quo Vadis Clozapine? A Bibliometric Study of 45 Years of Research in International Context

We have carried out a bibliometric study about the international scientific publications on clozapine. We have used the EMBASE and MEDLINE databases, and we applied bibliometric indicators of production, as Price’s Law on the increase of scientific literature. We also calculated the participation index (PI) of the different countries. The bibliometric data have also been correlated with some social and health data from the 12 most productive countries in biomedicine and health sciences. In addition, 5607 original documents dealing with clozapine, published between 1970 and 2013, were downloaded. Our results state non-fulfilment of Price’s Law, with scientific production on clozapine showing linear growth (r = 0.8691, vs. r = 0.8478 after exponential adjustment). Seven of the 12 journals with the highest numbers of publications on clozapine have an Impact Factor > 2. Among the countries generating clozapine research, the most prominent is the USA (PI = 24.32), followed by the UK (PI = 6.27) and Germany (PI = 5.40). The differences among countries on clozapine research are significantly related to economic variables linked to research. The scientific interest in clozapine remains remarkable, although after the application of bibliometric indicators of production, a saturation point is evident in the growth of scientific literature on this topic.     

Relationship between pharmacokinetics and the analgesic effect of ketorolac in the rat

The relationship between the pharmacokinetic properties and the analgesic effect of ketorolac was evaluated with the pain-induced functional impairment model in the rat. Female Wistar rats were injected with uric acid in the knee of the right hind limb to produce dysfunction. Then, animals received an oral dose of 0.3, 1, 1.8, 3.2 or 5.6 mg/kg of ketorolac tromethamine and analgesic effect and blood concentration, determined by high-performance liquid chromatography, were evaluated at selected times for a period of 4 hr. Ketorolac produced a dose-dependent analgesic effect, measured as a recovery of the functionality of the injured limb, which reached its maximal effect at doses of 3.2 mg/kg or higher. When functionality index was plotted against ketorolac blood concentration, a direct relationship was observed that was well described by the sigmoidal maximal effect model. The data strongly suggest that ketorolac's analgesic effect depends on the blood concentration of the drug.     

Photocatalytic gold recovery from spent cyanide plating bath solutions

A new procedure is presented for the photocatalytic treatment of the highly stable gold-cyanide complexes remaining in spent plating bath solutions. The process allows the recovery of gold by photocatalytic reduction, increasing simultaneously the availability of cyanide for removal treatment. Gold recovery requires a non-oxidant atmosphere and the presence of hydroxyl radical scavengers. The use of mixed TiO₂/SiO₂ photocatalysts leads to an improvement in the gold recovery rate.