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PubMed2003

Lack of intersite GABA receptor subtype antagonist effects upon mu opioid receptor agonist-induced feeding elicited from either the ventral tegmental area or nucleus accumbens shell in rats.

Pretreatment with the GABA(A) receptor antagonist, bicuculline or the GABA(B) receptor antagonist, saclofen, into the nucleus accumbens (Nacc) shell, respectively, potentiates and reduces feeding elicited by the mu opioid agonist, [D-Ala(2), Nme(4), Gly-ol(5)]-enkephalin (DAMGO), administered into the same site. DAMGO-induced feeding elicited from the ventral tegmental area (VTA) region is significantly reduced by pretreatment with saclofen into the same site indicating local GABA mediation of opioid-induced feeding in each site. Given the neuroanatomical and functional connections between the two sites, the present study evaluated the dose-dependent actions of bicuculline and saclofen pretreatment in one site upon DAMGO-induced feeding elicited from the second site. Pretreatment of either bicuculline (7.5-75 ng) or saclofen (1.5-10 microg) into the Nacc shell failed to alter the time course or magnitude of DAMGO-induced feeding elicited from the VTA region. DAMGO-induced feeding elicited from the Nacc shell was unaffected by VTA region pretreatment with either bicuculline (7.5-75 ng) or saclofen (1.5-5 microg). A higher (10 microg) saclofen dose prevented significant DAMGO-induced feeding after 1 and 4 h. Thus, although GABA receptor subtype antagonists are capable of differentially modulating DAMGO-induced feeding when both drugs are applied locally in either the VTA region or the Nacc shell, it appears that any effects between the VTA region and the Nacc shell in modulating DAMGO-induced feeding do not depend upon a GABAergic synapse in the other site.

Animals↗

PubMed2000

Dispersion of circumferential waves on evacuated, water-loaded spherical steel shells.

The phase-velocity dispersion curve of the A0 Lamb wave on a free plate tends to zero at the vanishing frequency while on an evacuated, free spherical shell, it turns upward. On a fluid-loaded shell, and for the analogous circumferential A0 wave, it again tends to zero, however, while a new A-wave (Scholte-Stoneley wave) which gets added due to fluid loading, is the one whose dispersion curve turns upward. This phenomenon is studied here for a thin stainless-steel shell on the basis of dispersion curves calculated from 3D elasticity theory, or obtained from the calculated shell resonances, and is explained by the physical nature (shell-borne or fluid-borne) of appropriate circumferential wave portions. We also establish connections with the previously found partial dispersion curves.

Acoustics↗

PubMed2000

Acoustic wave scattering from a composed shell reinforced by a single rib: characteristics of peripheral waves

The steady-state axisymmetrical problem of a plane acoustic wave scattering from a composed shell is considered. The shell has a cylindrical part and two hemispherical endcaps. The rib is a ring of rectangular cross-section that divides the shell into two equal parts. The motion of the shell and the rib is described by the equations of elasticity theory, and the liquid is described by the Helmholtz equation. The solution is obtained numerically by a coupled finite element/boundary element model. Two peripheral waves are generated in the shell: the membrane S0 wave and the bending type water-borne A wave. The form function, acoustic spectrogram and dispersion curves of the phase velocities are presented, and the effect of the rib on the peripheral waves is discussed.

Journal Article↗

PubMed2003

Evaluation of a rapid test (QuickVue) compared with the shell vial assay for detection of influenza virus clearance after antiviral treatment.

QuickVue influenza rapid diagnostic test (Quidel Corp., San Diego, CA, USA) was compared with the classical shell vial assay for evaluation of influenza virus clearance in patients treated with antiviral drugs. The shell vial assay was carried out on nasopharyngeal samples obtained from volunteers for a neuraminidase-inhibitor clinical trial protocol with 24 h or less from the onset of symptoms of influenza before the use of antiviral (day 1). Follow-up included samples collected after 24 and 72 h of therapy (day 2 and 4). The rapid test was retrospectively carried out in frozen samples. Test results on 99 samples from 33 adults were compared and the shell vial assay was considered the gold standard. The overall rate of detection for the shell vial assay was 39.4% and for QuickVue was 35.5%, with a concordance of 79.8%. The sensitivity obtained for QuickVue was 74.4% and the specificity was 82.7%. Comparison of test results day by day in the follow-up resulted: day 1, higher sensitivity of QuickVue test (85.5%, 24/29); day 2, agreement on positive and negative results between QuickVue and shell vial was 60.6% (20/33); day 4, all test results in samples collected after 72 h of therapy were negative. The QuickVue test showed good sensitivity for the diagnosis of influenza-like illnesses. This rapid test kit can be an alternative tool for interventions in disease management.

Adolescent↗

PubMed2003

The nucleus accumbens shell is critical for normal expression of pup-retrieval in postpartum female rats.

The nucleus accumbens (NA) plays an important modulatory role in the control of normal expression of maternal behavior (termed maternal performance). The present study investigated the relative functions of two subregions of the NA (the shell and core) in maternal performance. Electrolytic lesions of the shell or core were performed either before parturition or immediately after a varying amount of maternal experience (none, 1 or 24h) during the immediate postpartum period. Maternal performance was tested on Day 1 postpartum and re-tested 9 days later using a pup sensitization technique. Results show that lesions of the shell, but not the core, significantly disrupted pup-retrieval: the shell-lesioned rats took significantly longer to finish retrieving all test pups, but their retrieval latency for the first pup was not affected. Neither lesion affected other components of maternal behavior (pup licking, nest building and nursing). These findings suggest that the shell, but not the core, is critical for the normal expression of pup-retrieval behavior possibly through its role in maintaining maternal motivation or attention.

Animals↗

PubMed2002

Dissociation in the involvement of dopaminergic neurons innervating the core and shell subregions of the nucleus accumbens in latent inhibition and affective perception.

Mesencephalic dopaminergic neurons have been found to be involved in affective processes. Their implication in cognitive processes appears less well understood. The use of latent inhibition paradigms is a means of studying these kinds of processes. In this study, we investigated the involvement of dopaminergic projections in the core, the dorsomedial shell and the ventromedial shell of the nucleus accumbens, in latent inhibition in olfactory aversive learning. Variations in extracellular dopamine levels induced by an aversively conditioned olfactory stimulus were monitored in the three parts of the nucleus accumbens in the left hemisphere, after pre-exposure to the olfactory stimulus using in vivo voltammetry in freely moving rats. The parallel between dopamine changes and place preference or aversion toward the stimulus were analyzed in pre-exposed and non-pre-exposed animals. Results showed that dopaminergic neurons innervating the nucleus accumbens are differentially involved in the latent inhibition phenomenon. Dopaminergic neurons innervating the core and the dorsomedial shell subregions of the nucleus accumbens appeared to be involved in latent inhibition processes, unlike those reaching the ventromedial shell. Nonetheless dopamine in the ventromedial shell was found to be involved in affective perception of the stimulus.The present data suggest that dopaminergic neurons innervating the three nucleus accumbens subregions are functionally related to networks involved in parallel processing of the cognitive and affective values of environmental information, and that interaction between these systems, at some levels, may lead to a given behavioral output. These data may provide new insights into the pathophysiology of schizophrenic psychoses.

Affect↗

PubMed2000

Possible pathways through which neurons of the shell of the nucleus accumbens influence the outflow of the core of the nucleus accumbens.

The nucleus accumbens (Acb), a major sector of the ventral striatum, is considered to be an integral part of the striatal complex. The Acb has been shown to be composed of two subdivisions, core and shell, which are distinguishable in several aspects, suggesting that these two subdivisions play different functional roles. The aim of this study was to identify pathways of the efferents of the shell of the Acb to influence the outflow of the core of the Acb. Potential disynaptic projections of the shell to the core of the Acb were investigated in chloral hydrate-anesthetized male Sprague-Dawley rats. Following ipsilateral injections of biotinylated dextran amine (BDA) into the shell of the Acb and cholera toxin B subunit (CT-B) into the core, strong overlapping distributions of BDA-labeled terminals and CT-B-labeled neuronal cell somata were found in the medial part of the ventral tegmental area, medial part of the lateral hypothalamic area, and dorsolateral part of the basolateral amygdaloid nucleus. The significance of multiple sites of relay between the efferents of the shell and the afferents of the core of the Acb at different levels of the neuraxis may be related to the functional specificity of each relay site.

Animals↗

PubMed2001

Dissociable effects of antagonism of NMDA and AMPA/KA receptors in the nucleus accumbens core and shell on cocaine-seeking behavior.

The purpose of the present experiment was to investigate the involvement of NMDA and AMPA/KA receptors in the nucleus accumbens core and shell in the control over cocaine-seeking behavior by drug-associated cues. Rats were trained under a second-order schedule of reinforcement for cocaine with five infusions of cocaine being available in each daily session. The NMDA receptor antagonist AP-5 and the AMPA/KA receptor antagonist LY293558 were infused directly into the core or shell. LY293558 infused into the core produced a dose-dependent decrease in responding during both the first, cocaine-unaffected interval and also after cocaine had been self-administered in subsequent intervals. By contrast, AP-5 infused into the core had no effect on responding. Infusion of AP-5 into the shell had the limited effect of decreasing responding during the second interval only. There were no effects of LY293558 infused into the shell. These results indicate that NMDA and AMPA receptor-mediated glutamate transmission in the core and shell are dissociably involved in cocaine-seeking behavior controlled in part by drug-associated cues.

2-Amino-5-phosphonovalerate↗

PubMed2000

Effects of atypical antipsychotic drugs on dopamine output in the shell and core of the nucleus accumbens: role of 5-HT(2A) and alpha(1)-adrenoceptor antagonism.

The effects of acute intravenous administration of several new, atypical antipsychotic drugs (APDs): olanzapine (0.05 and 1.0 mg/kg), sertindole (0.1 and 1.0 mg/kg) and quetiapine (0.25 and 2.5 mg/kg), a selective 5-HT(2A) receptor antagonist, M100907 (0.03 and 0.3 mg/kg), and an alpha(1)-adrenoceptor antagonist, prazosin (0.3 mg/kg), on regional dopamine output were examined in the two subdivisions of the nucleus accumbens (NAC), the core and shell, which seem associated with motor control and limbic functions, respectively, by using in vivo differential normal pulse voltammetry in anaesthetised, pargyline-pretreated rats. Both quetiapine and sertindole, in the two doses used, caused a more pronounced dopamine release in the shell than in the core region of the NAC. In contrast, the low dose of olanzapine increased dopamine output almost to the same extent in both regions, whereas the high dose increased dopamine output to a greater extent in the core. M100907 selectively increased dopamine output in the shell. Also, prazosin significantly increased dopamine output in the shell, but not in the core. The results indicate that both 5-HT(2A) and alpha(1)-adrenoceptor antagonism may play an important role in the preferential effect of atypical APDs on dopamine output in the shell versus the core of the NAC.

Adrenergic Antagonists↗

PubMed2003

Cocoa shells for heavy metal removal from acidic solutions.

The development of economic and efficient processes for the removal of heavy metals present in acidic effluents from industrial sources or decontamination technologies has become a priority. The purpose of this work was to study the efficiency with which cocoa shells remove heavy metals from acidic solutions (pH 2) and to investigate how the composition of these solutions influences heavy metal uptake efficiency. Adsorption tests were conducted in agitated flasks with single-metal solutions (0.25 mM Al, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn), multi-metal solution (comprised of 0.25 mM of each of the cations above) and an effluent obtained from chemical leaching of metal-contaminated soil, in the presence of different cocoa shell concentrations (5-40 g/l). Results from the single-metal solution assays indicated that the fixation capacity of heavy metals by cocoa shells followed a specific order: Pb>Cr>Cd=Cu=Fe>Zn=Co>Mn=Ni=Al. Cocoa shells are particularly efficient in the removal of lead from very acidic solutions (q(max)=6.2 mg Pb/g, pH(i)=2.0 and T=22 degrees C). The presence of other metals and cations in solution did not seem to affect the recovery of lead. It was also observed that the maximum metal uptake was reached in less than 2 h. This research has also demonstrated that the removal of metals caused a decline in solution proton concentration (pH increase) and release of calcium, magnesium, potassium and sodium from the cocoa shells.

Cacao↗

PubMed2004

Shell of abalone Haliotis diversicolor supertexta can eliminate waterborne zinc biokinetically.

Dietary and nondietary accumulation of waterborne zinc (Zn) by shell of abalone Haliotis diversicolor supertexta was studied to determine if abalone shell can accumulate and eliminate Zn biokinetically. Shell of H. diversicolor supertexta rapidly accumulated Zn at microgram per gram concentrations during a 7-d uptake period for dietary and nondietary exposure to 1 microgml(-1) Zn seawater. Depuration half-lives were 7.22 and 15.40 d for dietary and nondietary exposure, respectively. The uptake rate constants were 5.12 and 4.84 ml g(-1)d(-1), respectively, for dietary and nondietary exposure. The depuration rate constants were 0.048 and 0.10 d(-1), respectively for dietary and nondietary exposure. Results from this study showed that the shell of H. diversicolor supertexta accumulated Zn and that it reflected the composition of the seawater in which the abalone lived. This suggested that the shell of H. diversicolor supertexta can be used as a bioindicator or can act as a receptor to biokinetically eliminate heavy metals from aquatic food webs.

Animal Structures↗

PubMed2002

The effect of vitamin C on the non-specific immune response of the juvenile soft-shelled turtle (Trionyx sinensis).

The study was conducted to determine the effect of supplementation vitamin C in dietary non-specific immunity in juvenile soft-shelled turtles. The soft-shelled turtles were fed with vitamin C supplementation at dosages of 0, 250, 500, 2500, 5000 and 10000 mg/kg diets, respectively, for 4 weeks. The results showed that there were no differences in the phagocytosis of blood cells, serum bacteriolytic activity and bactericidal activity among soft-shelled turtles fed with vitamin C supplementation in 0-500 mg/kg diets. However, firm indicators were significantly enhanced in soft-shelled turtles fed with vitamin C supplementation at 2500 mg/kg diets compared with those fed at 0 and 250 mg/kg diets. The soft-shelled turtles fed with 5000 mg/kg diets had only significantly higher bactericidal activity than those fed vitamin C-deficient diets. The vitamin C supplementation in 10000 mg/kg diets had no notable effects on the phagocytosis, bacteriolytic activity and bactericidal activity. These results suggest that vitamin C seems have an upper and lower threshold for improving non-specific immune function, and the optimum dose was 2500 mg/kg.

Animals↗

PubMed2003

A novel ferritin subunit involved in shell formation from the pearl oyster (Pinctada fucata).

Iron is one of the most important minor elements in the shell of bivalves. This study was designed to investigate the involvement of ferritin, the principal protein for iron storage, in shell formation. A novel ferritin cDNA from the pearl oyster (Pinctada fucata) was isolated and characterized. The ferritin cDNA encodes a 206 amino acid polypeptide, which shares high similarity with snail soma ferritin and the H-chains of mammalian ferritins. Oyster ferritin mRNA shows the highest level of expression in the mantle, the organ for shell formation. In situ hybridization analysis revealed that oyster ferritin mRNA is expressed at the highest level at the mantle fold, a region essential for metal accumulation and contributes to metal incorporation into the shell. Taken together, these results suggest that ferritin is involved in shell formation by iron storage. The identification and characterization of oyster ferritin also helps to further understand the structural and functional properties of molluscan ferritins.

Amino Acid Sequence↗

PubMed2000

EPR and IR spectral studies of the sea water mussel Mytilus conradinus shells.

The electron paramagnetic resonance (EPR) and infrared (IR) spectral studies have been employed on the periostracum, the prismatic layer and the nacre of the shell of the marine bivalve molluscan Mytilus conradinus of the South Indian origin. All the layers of this shell show Fe3+ ion spin resonance signals in common. The inner layer namely nacre at room temperature shows EPR signals of Fe3+ ions and the heated one exhibits a sextet hyperfine pattern characteristic of Mn2+ ions. The prismatic layer of the shell also exhibits a similar spectrum, but of distinct pattern. The spin-Hamiltonian parameters have been evaluated for the prismatic and nacreous layers of this shell. Infrared spectra of the two main layers of the shell namely prismatic and the nacre exhibit the characteristic bands of CO3(2-) molecular ion in different symmetries of CaCO3.

Animals↗

PubMed2002

Geometric hydration shells for anionic platinum group metal chloro complexes.

Solvation shells surrounding complex inorganic anions have not been extensively studied and are often mentioned with an amorphous picture in mind. We use a computational model previously validated against experimental results and ab initio quantum calculations (Lienke, A.; Klatt, G.; Robinson, D.; Koch, K. R.; Naidoo, K. J. Inorg.Chem. 2001, 40, 2352-2357) to investigate the nature of the hydration shells about simple platinum group metal chloro complexes ([PtCl(6)](2-), [RhCl(6)](3-), [PtCl(4)](2-), and [PdCl(4)](2-)). Our simulations show that the hydration shells surrounding these complexes are symmetric and take on familiar geometric forms. We find that only the [RhCl(6)](3-) complex has a clearly defined second hydration shell while the [PtCl(6)](2-), [PtCl(4)](2-), and [PdCl(4)](2-) second hydration shells are more diffuse.

Journal Article↗

PubMed2001

Tunable swelling kinetics in core--shell hydrogel nanoparticles.

Thermoresponsive, core--shell poly-N-isopropylacrylamide (p-NIPAm) nanoparticles (microgels) have been synthesized by seed and feed precipitation polymerization, and the influence of chemical differentiation between the core and shell polymers on the phase transition kinetics and thermodynamics has been examined. The results suggest that the core--shell architecture is a powerful one for the design of colloidal "smart gels" with tunable properties. To examine these materials, differential scanning calorimetry (DSC), (1)H NMR, and temperature-programmed photon correlation spectroscopy (TP-PCS) have been employed. These measurements show that the addition of small concentrations of a hydrophobic monomer (butyl methacrylate, BMA) into the particle shell produces large decreases in the rate of thermo-induced particle collapse. Conversely, these low levels of hydrophobic modification do not perturb the thermodynamics of the particle phase transition. When these results are examined in light of previous studies of macroscopic hydrogels, they suggest that the formation of a thin, stable skin layer at the particle exterior during the early stages of particle collapse is the rate limiting factor in particle deswelling. Finally, the hydrophobicity (BMA content) of the shell determines the magnitude of the hydrogel collapse rate, while the thickness of the BMA containing region does not impact the observed kinetics. Together, these results suggest that control over the kinetics of microgel deswelling events can be accomplished simply by modification of the particle periphery, and therefore do not require homogeneous modification of the entire polymer structure.

Journal Article↗

PubMed2001

Interfacial nonradiative energy transfer in responsive core-shell hydrogel nanoparticles.

Fluorescently labeled core-shell latex particles composed mainly of the thermoresponsive polymer poly-N-isopropylacrylamide (p-NIPAm) have been synthesized such that an energy transfer donor (phenanthrene) and an energy transfer acceptor (anthracene) are covalently localized in the core and shell, respectively. When the thermally induced particle deswelling is interrogated by photon correlation spectroscopy (PCS), a continuous (non-first order) phase transition is observed. Conversely, when the nonradiative energy transfer (NRET) efficiency is used to probe the collapse of these same particles, the phase transition event is observed to occur over a much smaller temperature range and approaches first-order (discontinuous) behavior. Furthermore, core-shell particles with differing shell thicknesses display identical phase transition temperatures when PCS is used to monitor the transition, while NRET measurements show a clear increase in collapse temperature as the shell thickness is increased. These apparently contradictory results are discussed in terms of a radial phase coexistence that exists in the microgel particles, which arises from a similarly radial inhomogeneity in the cross-linker concentration. The prospects for the NRET technique as a molecular-scale probe of nanostructured microgels are also discussed.

Biocompatible Materials↗

PubMed2005

Characterizing the "shell phase" formed from amphiphilic picolinates.

The shell phase forms when certain picolinates are subjected to energy input (via sonication or vortexing) while exposed to a water/toluene mixture. A shell, about 600 A thick and containing the picolinate and (very likely) toluene, surround the water droplets that are always produced during the mixing process. Solubility in either phase appears to be deleterious to shell formation. The shells, stable for months, are not easily distorted but can be punctured, even skewered, with a syringe needle without destroying the sphere, yet there is enough mobility among the molecules to repair the physical damage after the needle is removed. This, plus the absence of evidence for crystallinity, suggests a solid or semisolid film forms when picolinates, with the aid of an aromatic solvent, are provided the energy to rearrange themselves on water droplet surfaces. Structure-activity comparisons among the 10 compounds studied indicate that chain-chain association and intermolecular hydrogen bonding are dominant forces in a side-by-side self-assembly of the molecules within the shells.

Anesthetics, Local↗