Determination of fluoxetine and norfluoxetine enantiomers in human plasma by polypyrrole-coated capillary in-tube solid-phase microextraction coupled with liquid chromatography-fluorescence detection

A sensitive, selective, and reproducible in-tube polypyrrole-coated capillary (PPY) solid-phase microextraction and liquid chromatographic method for fluoxetine and norfluoxetine enantiomers analysis in plasma samples has been developed, validated, and further applied to the analysis of plasma samples from elderly patients undergoing therapy with antidepressants. Important factors in the optimization of in-tube SPME efficiency are discussed, including the sample draw/eject volume, draw/eject cycle number, draw/eject flow-rate, sample pH, and influence of plasma proteins. Separation of the analytes was achieved with a Chiralcel OD-R column and a mobile phase consisting of potassium hexafluorophosphate 7.5 mM and sodium phosphate 0.25 M solution, pH 3.0, and acetonitrile (75:25, v/v) in the isocratic mode, at a flow rate of 1.0 mL/min. Detection was carried out by fluorescence absorbance at Ex/Em 230/290 nm. The multifunctional porous surface structure of the PPY-coated film provided high precision and accuracy for enantiomers. Compared with other commercial capillaries, PPY-coated capillary showed better extraction efficiency for all the analytes. The quantification limits of the proposed method were 10 ng/mL for R- and S-fluoxetine, and 15 ng/mL for R- and S-norfluoxetine, with a coefficient of variation lower than 13%. The response of the method for enantiomers is linear over a dynamic range, from the limit of quantification to 700ng/mL, with correlation coefficients higher than 0.9940. The in-tube SPME/LC method can therefore be successfully used to analyze plasma samples from ageing patients undergoing therapy with fluoxetine. (C) 2009 Elsevier B.V. All rights reserved.

High speed versus conventional grinding in high removal rate machining of alumina and alumina-titania

High removal rate (up to 16.6 mm(3)/s per mm) grinding of alumina and alumina-titania was investigated with respect to material removal and basic grinding parameters using a resin-bond 160 mu m grit diamond wheel at the speeds of 40 and 160 m/s, respectively. The results show that the material removal for the single-phase polycrystalline alumina and the two-phase alumina-titania composite revealed identical mechanisms of microfracture and grain dislodgement under the grinding conditioned selected. There were no distinct differences in surface roughness and morphology for both materials ground at either conventional or high speed. An increase in material removal rate did not necessarily worsen the surface toughness for the two materials at both speeds. Also the grinding forces for the two ceramics demonstrated similar characteristics at any grinding speeds and specific removal rates. Both normal and tangential grinding forces and their force ratios at the high speed were lower than those at the conventional speed, regardless of removal rates. An increase in specific removal rate caused more rapid increases in normal and tangential forces obtained at the conventional grinding speed than those at the high speed. Furthermore, it is found that the high speed grinding at all the removal rates exerted a great amount of coolant-induced normal forces in grinding zone, which were 4-6 times higher than the pure normal grinding forces. (c) 2004 Elsevier Ltd. All rights reserved.

Effects of microinjections of apomorphine and haloperidol into the inferior colliculus on the latent inhibition of the conditioned emotional response

Electrical or chemical stimulation of the inferior colliculus (IC) induces fear-like behaviors. More recently, consistent evidence has shown that electrical stimulation of the central nucleus of the IC supports Pavlovian conditioning and latent inhibition (Li). LI is characterized by retardation in conditioning and also by an impaired ability to ignore irrelevant stimuli, after a non-reinforced pre-exposure to the conditioned stimulus. LI has been proposed as a behavioral model of cognitive abnormalities seen in schizophrenia. The aim of the present study was to determine whether dopaminergic mechanisms in the IC are involved in LI of the conditioned emotional response (CER). To induce LI, a group of rats was pre-exposed (PE) to six tones in two sessions, while rats that were not pre-exposed (NPE) had two sessions without tone presentations. The conditioning consisted of two tone presentations to the animal, followed immediately by a foot shock. PE and NPE rats received IC microinjections of physiological saline, the dopaminergic agonist apomorphine (9.0 mu g/0.5 mu L/side), or the dopaminergic antagonist haloperidol (0.5 mu g/0.5 mu L/side) before both pre-exposure and conditioning. During the test, the PE rats that received saline or haloperidol had a lower suppression of the licking response compared to NPE rats that received vehicle or haloperidol, indicating that latent inhibition was induced. There was no significant difference in the suppression ratio in rats that received apomorphine injections into the IC, indicating reduced latent inhibition. These results suggest that dopamine-mediated mechanisms of the IC are involved in the development of LI. (C) 2008 Elsevier Inc. All rights reserved.

Patterns of brain asymmetry in the perception of positive and negative facial expressions

The divided visual field technique was used to investigate the pattern of brain asymmetry in the perception of positive/approach and negative/withdrawal facial expressions. A total of 80 undergraduate students (65 female, 15 male) were distributed in five experimental groups in order to investigate separately the perception of expressions of happiness, surprise, fear, sadness, and the neutral face. In each trial a target and a distractor expression were presented simultaneously in a computer screen for 150 ms and participants had to determine the side (left or right) on which the target expression was presented. Results indicated that expressions of happiness and fear were identified faster when presented in the left visual field, suggesting an advantage of the right hemisphere in the perception of these expressions. Fewer judgement errors and faster reaction times were also observed for the matching condition in which emotional faces were presented in the left visual field and neutral faces in the right visual field. Other results indicated that positive expressions (happiness and surprise) were perceived faster and more accurately than negative ones (sadness and fear). Main results tend to support the right hemisphere hypothesis, which predicts a better performance of the right hemisphere to perceive emotions, as opposed to the approach-withdrawal hypothesis.

Serotonin-1A receptors in the dorsal periaqueductal gray matter mediate the panicolytic-like effect of pindolol and paroxetine combination in the elevated T-maze

The beta-adrenergic blocker and 5-HT(1A) receptor antagonist pindolol has been combined with selective serotonin reuptake inhibitors (SSRIs) in patients with depressive and anxiety disorders to shorten the onset of the clinical action and/or increase the proportion of responders. The results of a previous study have shown that pindolol potentiates the panicolytic effect of paroxetine in rats submitted to the elevated T-maze (ETM). Since reported evidence has implicated the 5-HT(1A) receptors of the dorsal periaqueductal gray matter (DPAG) in the panicolytic effect of antidepressants, rats treated with pindolol (5.0 mg/kg, i.p.) and paroxetine (1.5 mg/kg, i.p.) received a previous intra-DPAG injection of the selective 5-HT(1A) antagonist, WAY-100635 (0.4 mu g) and were submitted to the ETM. Pretreatment with WAY-100635 reversed the increase in escape latency, a panicolytic effect, determined by the pindolol-paroxetine combination. These results implicate the 5-HT(1A) receptors of the DPAG in the panicolytic effect of the pindolol-paroxetine combination administered systemically. They also give further preclinical support for the use of this drug combination in the treatment of panic disorder. (C) 2011 Elsevier Ireland Ltd. All rights reserved.

Regulation of conditioned and unconditioned fear in rats by 5-HT1A receptors in the dorsal periaqueductal gray

Studies on the involvement of 5-HT1-mediated mechanisms in the dorsal periaqueductal gray (dPAG) of animals with past stressful experiences have not been conducted so far. We investigated the role of 5-HT1 receptors in the dPAG of rats previously submitted to contextual fear conditioning. Defensive behaviors induced by activation of the dPAG were assessed by measuring the lowest electric current applied to this structure (threshold) able to produce freezing and escape responses during testing sessions of contextual fear conditioning, in which animals were placed in a context previously paired to footshocks. The 5-HT1A function of the dPAG was evaluated by local injections of 8-OH-DPAT (4 and 8 nmol/0.2 mu L) and WAY-100635 (10 nmol/0.2 mu L), selective agonist and antagonist of 5-HT1A receptors, respectively. In accordance with previous studies, 8-OH-DPAT increased aversive thresholds (antiaversive effects) but injections of WAY 100635 into the dPAG did not produce significant effects on the aversive thresholds in naive rats. However, the aversive thresholds of animals exhibiting contextual fear remained unchanged with both treatments. Moreover, 8-OH-DPAT and WAY 100635 did not change the dPAG post-stimulation freezing. The present results suggest that the stressful experience of being fear conditioned has an effect on the role of the 5-HT1A receptors in mediating unconditioned fear. Also, the reduction in the regulation of the defensive behaviors by 5-HT1A-mediated mechanisms in the dPAG of these animals may underlie the stress precipitated psychopathology associated with the neural substrates of aversion of the dPAG. (c) 2007 Elsevier Inc. All rights reserved.

Degradation of phenanthrene and pyrene in soil slurry reactors with immobilized bacteria Zoogloea sp.

The environmental fate of polycyclic aromatic hydrocarbons (PAHs) in soils is motivated by their wide distribution, high persistence, and potentially deleterious effect on human health. Polycyclic aromatic hydrocarbons constitute the largest group of environmental contaminants released in the environment. Therefore, the potential biodegradation of these compounds is of vital importance. A biocarrier suitable for the colonization by micro-organisms for the purpose of purifying soil contaminated by polycyclic aromatic hydrocarbons was developed. The optimized composition of the biocarrier was polyvinyl alcohol (PVA) 10%, sodium alginate (SA) 0.5%, and powdered activated carbon (PAC) 5%. There was no observable cytotoxicity of biocarriers on immobilized cells and a viable cell population of 1.86 x 10(10) g(-1) was maintained for immobilized bacterium. Biocarriers made from chemical methods had a higher biodegradation but lower mechanical strengths. Immobilized bacterium Zoogloea sp. had an ideal capability of biodegradation for phenanthrene and pyrene over a relative wide concentration range. The study results showed that the biodegradation of phenanthrene and pyrene reached 87.0 and 75.4%, respectively, by using the optimal immobilized method of Zoogloea sp. cultivated in a sterilized soil. Immobilized Zoogloea sp. was found to be effective for biodegrading the soil contaminated with phenanthrene and pyrene. Even in natural (unsterilized) soil, the biodegradation of phenanthrene and pyrene using immobilized Zoogloea sp. reached 85.0 and 67.1%, respectively, after 168 h of cultivation, more than twice that achieved if the cells were not immobilized on the biocarrier. Therefore, the immobilization technology enhanced the competitive ability of introduced micro-organisms and represents an effective method for the biotreatment of soil contaminated with phenanthrene and pyrene.

Cyanocobalt(III) complexes of penta- and tetradentate-coordinated macrocyclic hexaamines

The pendent-arm macrocyclic hexaamine trans-6,13-dimethyl-1,4,8,11-tetraazacyclotetradecane-6,13-diamine (L) may coordinate in tetra-, penta- or hexadentate modes, depending on the metal ion and the synthetic procedure. We report here the crystal structures of two pseudo-octahedral cobalt(III) complexes of L, namely sodium trans-cyano(trans-6,13-dimethyl-1,4,8,11-tetraazacyclotetradecane-6,13-diamine)cobalt(III) triperchlorate, Na[Co(CN)(C13H30N6)](ClO4)(3) or Na{trans-[CoL(CN)]}(ClO4)(3), (I), where L is coordinated as a pentadentate ligand, and trans-dicyano(trans-6,13-dimethyl-1,4,8,11-tetraazacyclotetradecane-6,13-diamine) cobalt (III) trans-dicyano (trans-6,13-dimethyl-1,4,8,11-tetraazacyclotetradecane-6,13-diaminium)cobalt(III) tetraperchlorate tetrahydrate, [Co(CN)(2)(Cl4H32N6)][Co(CN)(2)(Cl4H30N6)](ClO4)(4)•-4H(2)O or trans-[CoL(CN)(2)]trans-[Co(H2L)(CN)(2)] (ClO4)(4)•-4H(2)O, (II), where the ligand binds in a tetradentate mode, with the remaining coordination sites being filled by C-bound cyano ligands. In (I), the secondary amine Co-N bond lengths lie within the range 1.944 (3)-1.969 (3) &ANGS;, while the trans influence of the cyano ligand lengthens the Co-N bond length of the coordinated primary amine [Co-N = 1.986 (3) &ANGS;]. The Co-CN bond length is 1.899 (3) &ANGS;. The complex cations in (11) are each located on centres of symmetry. The Co-N bond lengths in both cations are somewhat longer than in (I) and span a narrow range [1.972 (3)-1.982 (3) &ANGS;]. The two independent Co-CN bond lengths are similar [1.918 (4) and 1.926 (4) &ANGS;] but significantly longer than in the structure of (1), again a consequence of the trans influence of each cyano ligand.

A new species of Phylloicus Muller, 1880 (Trichoptera: Calamoceratidae), from southeastern Brazil, including descriptions of larval and pupal stages

The cosmopolitan family Calamoceratidae Ulmer, 1906, has 8 living genera, among them Phylloicus Muller, 1880, with species distributed from South to Central America. This genus is characterized by its dark-colored adults (brown to black) with diurnal to crepuscular habits. In this paper, the adults, pupae, and larvae of Phylloicus camargoi n. sp. are described and illustrated. The new species is easily diagnosed by male tergum X bearing a short, digitate, setose, basodorsal process; 2 short, digitate, hairless, lateral processes; and 2 pairs of very short processes on the posterior margin: a pair of digitate, hairless, posterolateral processes, and a pair of posteromesal processes. Additional diagnostic characters are the presence of 3 color bands on the forewings, 2 golden longitudinal bands and a white transversal one.

Adsorption of phenylalanine on layered double hydroxides: effect of temperature and ionic strength

In this work we report the adsorption of phenylalanine (Phe) on Magnesium Aluminum Layered Double Hydroxides (Mg-Al-CO(3)-LDH) at two different temperatures (298 and 310 K) and under two distinct ionic strength conditions (with and without the addition 0.1 M of NaCl). The adsorption isotherms exhibit the same profile in all conditions, and they only differ in the amount of removed Phe. At lower ionic strength, the isotherms are almost identical at both temperatures, except for the last points, where the increase in temperature causes a decrease in the amount of adsorbed Phe. An increase in ionic strength results in a decrease in Phe adsorption. The electrokinetic potential decreases as the amount of adsorbed Phe increases, and only positive values are observed. This indicates that the surface of the adsorbent is not totally neutralized and suggests that more Phe could be removed by adsorption. The presence of Phe on the solid is confirmed by FTIR spectra, which present the specific bands assigned to Phe. The hydrophobicity of the amino acid probably contributes to its extraction, thus enabling the removal of a great amount of Phe. In conclusion, LDH is potentially applicable in the removal of Phe from wastewater.

Children`s oral production of narratives and constructive memory using prior reading of pictures

With the purpose of approximating two issues, oral narrative and constructive memory, we assume that children, as well as adults, have a constructive memory. Accordingly, researchers of the constructive memory share with piagetians the vision that memory is an applied cognition. Under this perspective, understanding and coding into memory constitute a process which is considered similar to the piagetian assimilation of building an internal conceptual representation of the information (hence the term constructive memory. The objective of this study is to examine and illustrate, through examples drawn from a research about oral narrative with 5, 8 and 10 years old children, the extent to which the constructive memory is stimulated by the acquisition of the structures of knowledge or ""mental models"" (schemes of stories and scenes, scripts), and if they automatically employ them to process constructively the information in storage and rebuild them in the recovery. A sequence of five pictures from a book without text was transformed into computerized program, and the pictures were thus presented to the children. The story focuses on a misunderstanding of two characters on a different assessment about a key event. In data collection, the demands of memory were preserved, since children narrate their stories when the images were no longer viewed on the computer screen. Each narrative was produced as a monologue. The results show that this story can be told either in a descriptive level or in a more elaborated level, where intentions and beliefs are attributed to the characters. Although this study allows an assessment of the development of children`s capabilities (both cognitive and linguistic) to narrate a story, there are for sure other issues that could be exploited.