Solvay

About: Solvay is a company organization based out in Brussels, Belgium. It is known for research contribution in the topics: Catalysis & Polymer. The organization has 6083 authors who have published 7004 publications receiving 105745 citations.

Serotonin receptors and animal models of aggressive behavior.

Abstract: Various models of rodent agonistic behavior are described, which differentiate between offensive and defensive/flight models. Particular attention is given to one male and one female paradigm for offensive aggression, i.e. resident/intruder or territorial aggression (RI) and maternal aggression (MA). After an overview of the serotonin (5-HT) system in the CNS, a description is given of the ligands available. Subsequently, the effects of various drugs affecting serotonergic transmission in the RI- and MA-paradigms are described. The 5-HT1A receptor agonists busipirone, ipsapirone, and 8-OH-DPAT decreased aggression in RI and MA, but simultaneously led to a marked decrease in social interest and activity, indicative of a nonspecific antiaggressive profile. Nonselective 5-HT1 receptor agonists, such as RU24969, eltoprazine, and TFMPP reduced aggression quite specifically, did not decrease social interest or exploration, and sometimes even increased these behaviors. In RI and MA, the behavioral effects of these drugs were roughly similar. In contrast, MA was more sensitive to treatment with the 5-HT reuptake blocker fluvoxamine, which blocked RI aggression nonspecifically at the highest dose only. DOI, a 5-HT2A/2C# receptor agonist, decreased aggressive behavior and increased inactivity, without affecting social interest and exploration in RI as well as MA. This was, however, accompanied by "wet dog shaking" characteristic of 5-HT2 receptor stimulation. The nonspecific 5-HT receptor agonist (and 5-HT2 receptor antagonist) quipazine also induced "wet dog shaking" at doses which suppressed aggression, social interest, and exploration but increased inactive behaviors (sitting and lying). The discussion delineates a specific role for 5-HT1B receptor-subtype involvement in the modulation of aggression, with the restrictions we clearly face with regard to the lack of specific serotonergic agonists and antagonists for certain receptor subtypes. By and large, male and female rats react similarly to treatment with serotonergic drugs, and this fact underlines the consistent role of 5-HT in different forms of aggression.

Clinical Pharmacokinetics of Selective Serotonin Reuptake Inhibitors

Abstract: A feature common to all selective serotonin reuptake inhibitors (SSRIs) is that they are believed to act as antidepressant drugs because of their ability to reversibly block the reuptake of serotonin (5-hydroxytryptamine; 5-HT) in the synaptic cleft From a chemical perspective, however, they show distinct differences Consequently, the pharmacokinetic behaviour of of the drugs can be very different, and these pharmacokinetic differences may have a major influence on their clinical profiles of action All SSRIs have a great affinity for the 5-HT reuptake carrier in the synaptic cleft in the central nervous system, with much less affinity for the noradrenaline (norepinephrine) reuptake carrier, and for alpha- and beta-adrenergic, dopamine, histamine, 5-HT and muscarine receptors Fluoxetine and citalopram are available as racemic mixtures, the isomers of fluoxetine having almost equal affinity to the 5-HT reuptake carrier, while the reuptake inhibitor properties of citalopram reside almost exclusively in the (+)-isomer Norfluoxetine, one of the metabolites of fluoxetine, has a selectivity for the 5-HT reuptake carrier comparable with that of fluoxetine Gastrointestinal absorption of the SSRIs is generally good, with peak plasma concentrations observed after approximately 4 to 6h Absolute bioavailability of citalopram is almost 100%, whereas it is likely that the other compounds undergo (substantial) first-pass metabolism Apparent oral clearance values after single doses range from 26 L/h (citalopram) to 167 L/h (paroxetine), while after multiple doses oral clearance is markedly reduced, particularly for fluoxetine and paroxetine Plasma protein binding of fluoxetine, paroxetine and sertraline is > or = 95%; values for fluvoxamine (77%) and citalopram (50%) are much lower For all compounds, however, protein binding interactions do not seem to be of great importance Although many attempts were made, to date no convincing evidence exists of a relationship between plasma concentrations of any of the SSRIs and clinical efficacy Elimination occurs via metabolism, probably in the liver Renal excretion of the parent compounds is of minor importance Metabolites of fluvoxamine and fluoxetine are predominantly excreted in urine; larger quantities of metabolites of paroxetine (36%) and sertraline (44%) are excreted in faeces The half-lives of fluvoxamine, paroxetine, sertraline and citalopram are approximately 1 day The half-life of fluoxetine is approximately 2 days (6 days after multiple doses), and that of the active metabolite norfluoxetine is 7 to 15 days The metabolism of paroxetine, and possibly also of fluoxetine, is under genetic control of the sparteine/debrisoquine type Available data indicate that metabolism of SSRIs is impaired with reduced liver function(ABSTRACT TRUNCATED AT 400 WORDS)

Testosterone concentrations in diabetic and nondiabetic obese men.

Abstract: Objective: To determine the prevalence of subnormal testosterone concentrations in patients with obesity and with type 2 diabetes in a primary care clinic population. Research Design and Methods: FT concentrations of 1849 men(1451 non-diabetic and 398 diabetic) in the Hypogonadism In Males(HIM) study were analyzed. HIM study was a US based cross-sectional study designed to define the prevalence of hypogonadism in men older than 45 years. FT was measured by equilibrium dialysis. Results: Prevalence of subnormal FT concentrations in lean, overweight and obese non-diabetic men was 26%(n=275), 29%(n=687) and 40%(n=489) respectively(p Conclusion: 40% of obese non-diabetic and 50% of obese diabetic men above the age of 45 years have subnormal FT concentrations. In view of its high prevalence, obesity is probably the condition most frequently associated with subnormal FT concentration in males. The concomitant presence of diabetes is associated with an additional increase in prevalence of subnormal FT concentration.

Molecular characterization of maleic anhydride-functionalized polypropylene

Abstract: This work deals with the molecular characterization of maleic anhydride melt-functionalized polypropylene (PP-g-MA). The functionalization mechanism, the nature, the concentration, and the location of grafted anhydride species onto the polypropylene chain are discussed. The polypropylene functionalization was performed using a pre-heated Brabender Plastograph (190 degrees C, 4 min of mixing time). Several concentrations of maleic anhydride and organic peroxide were used for this study. In those experimental conditions, the organic peroxide undergoes an homolytic rupture and carries out a polypropylene tertiary hydrogen abstraction. The resulting macroradical undergoes a beta-scission leading to a radical chain end which reacts with maleic anhydride. When a termination reaction occurs at this first step a succinic type anhydride chain end is obtained. However, oligomerization of maleic anhydride is found to occur more frequently leading to poly( maleic anhydride) chain end. Concentration of both anhydride types and minimal length of the grafted poly(maleic anhydride) were determined. A fraction of maleic anhydride does not react with polypropylene or homopolymerize leading to nongrafted poly(maleic anhydride). (C) 1995 John Wiley and Sons, Inc.