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PubMed1992

Differential membrane properties and dopamine effects in the shell and core of the rat nucleus accumbens studied in vitro.

Electrophysiological differences between the shell and core of the rat nucleus accumbens were investigated by intracellular recordings from an in vitro slice preparation. The average input resistance of neurons recorded in the shell was larger than in the core. Neurons in the core were characterized by a more negative resting membrane potential than neurons in the shell. Furthermore, bath-applied dopamine attenuated synaptic responses recorded in the shell, but not in the core. Thus, the two main subregions of the nucleus accumbens differ both in basal membrane properties and in dopaminergic modulation of synaptic transmission.

Action Potentials↗

PubMed1996

Differential actions of typical and atypical antipsychotic drugs on dopamine release in the core and shell of the nucleus accumbens.

The effects of acute administration of typical and atypical antipsychotic drugs on extracellular dopamine (DA) concentrations in brain were examined in two subdivisions of the nucleus accumbens (NAC), the core and the shell, which are largely associated with motor control and limbic functions, respectively, by using in vivo differential normal pulse voltammetry in anesthetized, pargyline pretreated rats. The following drugs were studied: haloperidol (0.1 and 1.0 mg/kg), clozapine (1.0 and 5.0 mg/kg), amperozide (1.0 and 2.0 mg/kg), risperidone (0.1 and 1.0 mg/kg), the selective 5-HT2A/5-HT2C receptor antagonist ritanserin (1 mg/kg) and the selective DA-D2/D3 receptor antagonist raclopride (10 and 320 micrograms/kg). Drugs with predominantly high 5-HT2 receptor antagonistic action, such as amperozide and ritanserin, as well as low doses of either risperidone or clozapine increased DA concentrations to a greater extent in the shell than in the core subdivision of the NAC. In contrast, drugs with a more potent D2 receptor antagonistic action, such as haloperidol and raclopride, as well as high doses of either risperidone or clozapine, elicited a larger DA increase in the core than in the shell. Consequently, atypical antipsychotics characterized by potent 5-HT2 receptor antagonism can be differentiated from typical antipsychotic drugs on the basis of their preferential effect on DA transmission in the shell region of the NAC.

Animals↗

PubMed1994

Identification of influenza A virus by shell vial culture and two commercially available antigen detection methods.

BACKGROUND: Influenza continues to be a major cause of morbidity and mortality especially in the elderly and persons with underlying disease. Shell vial cell culture and antigen detection techniques may speed up diagnosis and enable better patient treatment and management. OBJECTIVES: To compare shell vial centrifugation culture with commercially available direct fluorescence and enzyme immunoassay kits using a variety of respiratory specimens. STUDY DESIGN: To detect influenza A virus, we compared direct fluorescent antibody (DFA) staining using the Bartels Viral Respiratory Panel and the Directigen FLU-A enzyme immunoassay (EIA) with shell vial centrifugation culture. Ninety-seven fresh specimens from a variety of respiratory sources, and transported from hospitals throughout the U.S. to our national referral laboratory, were tested. RESULTS: Fifteen specimens were true positives: culture positive or both antigen tests positive. Sensitivity with culture was 93%, EIA 67%, and DFA 47%. Specificity was excellent with all three methods: 100%, 98%, 99%. Culture detected additional viruses that can cause respiratory tract disease: herpes simplex, cytomegalovirus, respiratory syncytial, influenza B, and adenovirus. Fourteen (70%) of 20 frozen specimens previously positive for influenza A were positive on retest by EIA. Overall sensitivity of EIA compared with culture using 35 positive specimens was 69%. CONCLUSIONS: The rapid EIA is useful to screen for influenza A, but critical antigen-negative specimens should be submitted to a virology laboratory for culture. Shell vial cultures can provide a sensitive and universal diagnostic system for influenza A and a variety of other viruses.

Journal Article↗

PubMed2004

Fixation strength of an all-metal acetabular component cemented into an acetabular shell: a biomechanical analysis.

When an acetabular shell is well fixed but the locking mechanism is compromised, cementing a new liner into the existing acetabular component can provide a simple revision solution. The pull-out and torsional fixation strength of cobalt chromium (CoCr) alloy acetabular components cemented into 3 sizes of titanium alloy acetabular components was tested under conditions of 0 or 2 mm cement mantle at the dome and 2 mm cement with the cemented component in 20 degrees of version with respect to the shell. The lowest mean tensile load to failure was 1500 N, and occurred with no cement at the dome of the 54 mm shell, whereas the greatest load was with 2 mm cement thickness. Smallest mean torque to failure was 43 Nm. Version angle did not substantially change failure load. Although not cyclically loaded, fixation strength of metal liners cemented into shells was comparable to that of commonly used locking mechanisms, suggesting sufficient strength for clinical application.

Acetabulum↗

PubMed2006

Factors influencing the initial micromotion between polyethylene acetabular cups and titanium alloy shells.

Mechanical test factors affecting short-term rotational stability under combined torsional and compressive loading was assessed in modular press-fit acetabular components with 4 different locking mechanism designs, by measuring the micromotion of the liner-shell interface at either room (20 degrees C) or body temperature (37 degrees C) and with either a high (2,943 N) or low (490 N) compressive load. Liner-shell constructs whose short-term stability was statistically significantly affected by temperature exhibited more rotational stability at body temperature than at room temperature. Liner-shell constructs whose short-term stability was statistically significantly affected by the level of compressive load exhibited more rotational stability with high compressive loads than with low loads. Liner-shell constructs with different locking mechanism designs were influenced by temperature and compressive loads differently. It is recommended to consider including these factors in tests of acetabular component locking mechanisms.

Acetabulum↗

PubMed2005

Electrolytic lesions to nucleus accumbens core and shell have dissociable effects on conditioning to discrete and contextual cues in aversive and appetitive procedures respectively.

The nucleus accumbens (n. acc.) has been implicated in conditioning to both discrete and contextual cues but its precise role is as yet controversial because conflicting patterns of effect have been reported. These inconsistencies may relate to the extent to which the lesions used encroach on different subfields of n. acc. and the use of different task variants. The present study compared the effects of selective lesions of shell and core subfields of nucleus accumbens (n. acc.) across aversive and appetitive trace conditioning variants. In both experiments, an auditory stimulus was contiguous with footshock or food, or presented at a trace interval. A continuous flashing light in each case provided an experimental background stimulus. Conditioning to the cues provided by the experimental chambers was also assessed. Rats with electrolytic lesions to the n. acc. shell and core showed different patterns of effect in aversive (Experiment 1) and appetitive (Experiment 2) variants of this procedure. In Experiment 1, the core lesion reduced the difference between trace and contiguously conditioned groups, in responding to the discrete noise stimulus. However, neither lesion had any detectable effect on contextual conditioning. In Experiment 2, the shell lesion clearly increased contextual conditioning, selectively in the trace conditioned group, but neither lesion had any detectable effect on discrete cue conditioning. Thus, whilst the shell and core lesions produced dissociable effects on discrete cue and contextual conditioning, the conclusions to be drawn depend on the procedural variant in use.

Animals↗

PubMed2004

Pecan shell-based granular activated carbon for treatment of chemical oxygen demand (COD) in municipal wastewater.

The present investigation was undertaken to compare the adsorption efficiency of pecan shell-based granular activated carbon with the adsorption efficiency of the commercial carbon Filtrasorb 200 with respect to uptake of the organic components responsible for the chemical oxygen demand (COD) of municipal wastewater. Adsorption efficiencies for these two sets of carbons (experimental and commercial) were analyzed by the Freundlich adsorption model. The results indicate that steam-activated and acid-activated pecan shell-based carbons had higher adsorption for organic matter measured as COD, than carbon dioxide-activated pecan shell-based carbon or Filtrasorb 200 at all the carbon dosages used during the experiment. The higher adsorption may be related to surface area as the two carbons with the highest surface area also had the highest organic matter adsorption. These results show that granular activated carbons made from agricultural waste (pecan shells) can be used with greater effectiveness for organic matter removal from municipal wastewater than a coal-based commercial carbon.

Adsorption↗

PubMed2005

Biosorption of copper(II) and cobalt(II) from aqueous solutions by crab shell particles.

Biosorption of each of the heavy metals, copper(II) and cobalt(II) by crab shell was investigated in this study. The biosorption capacities of crab shell for copper and cobalt were studied at different particle sizes (0.456-1.117 mm), biosorbent dosages (1-10 g/l), initial metal concentrations (500-2000 mg/l) and solution pH values (3.5-6) in batch mode. At optimum particle size (0.767 mm), biosorbent dosage (5 g/l) and initial solution pH (pH 6); crab shell recorded maximum copper and cobalt uptakes of 243.9 and 322.6 mg/g, respectively, according to Langmuir model. The kinetic data obtained at different initial metal concentrations indicated that biosorption rate was fast and most of the process was completed within 2h, followed by slow attainment of equilibrium. Pseudo-second order model fitted the data well with very high correlation coefficients (>0.998). The presence of light and heavy metal ions influenced the copper and cobalt uptake potential of crab shell. Among several eluting agents, EDTA (pH 3.5, in HCl) performed well and also caused low biosorbent damage. The biosorbent was successfully regenerated and reused for five cycles.

Absorption↗

PubMed2005

Core--shell nanocluster films of hemoglobin and clay nanoparticle: direct electrochemistry and electrocatalysis.

A novel core-shell protein nanocluster film, designated as clay-(Hb/PSS)(n), was fabricated on pyrolytic graphite (PG) electrodes. Positively charged hemoglobin (Hb) at pH 5.5 and negatively charged poly(styrenesulfonate) (PSS) were first assembled layer by layer on surface of clay nanoparticles from their solutions mainly by electrostatic attraction, forming a core-shell nanocluster structure in which clay nanoparticles were the "cores" and (Hb/PSS)(n) multilayers were the "shells". The aqueous dispersion of clay-(Hb/PSS)(n) nanoclusters was then cast on surface of PG electrodes, forming clay-(Hb/PSS)(n) nanocluster films after evaporation of solvent. Hb in clay-(Hb/PSS)(n) films exhibited a pair of well-defined and reversible cyclic voltammetric (CV) peaks at about -0.36 V vs. SCE in pH 7.0 buffers, characteristic of Hb heme Fe(III)/Fe(II) redox couples. Compared with other Hb-containing clay films, clay-(Hb/PSS)(n) films displayed smaller CV peak separation (DeltaE(p)), indicating the better electrochemical reversibility of Hb in these nanocluster films. The partially ordered structure of the films was characterized by X-ray diffraction (XRD) experiments. UV-VIS and reflection absorption infrared (RAIR) spectroscopy suggests that Hb retains its near-native structure in clay-(Hb/PSS)(n) films. Oxygen, hydrogen peroxide, and nitrite were catalytically reduced at clay-(Hb/PSS)(n) film electrodes, showing the potential applicability of the films as the new type of biosensors or bioreactors based on protein direct electrochemistry. The electrochemical and electrocatalytic activity of the films could be tailored by controlling the number of bilayers of the (Hb/PSS)(n) shells on the surface of clay nanoparticle cores.

Aluminum Silicates↗

PubMed2004

Cloning and expression of a pivotal calcium metabolism regulator: calmodulin involved in shell formation from pearl oyster (Pinctada fucata).

The shells of bivalves are mainly composed of calcium carbonate, a product of calcium metabolism. In the process of shell formation, the uptake, transport and recruitment of calcium ion are highly regulated and involved in many factors. Among these regulatory factors, calmodulin (CaM), a pivotal multifunction regulator of calcium metabolism in nearly all organisms, is thought to play an important role in the calcium metabolism involved in shell formation. In this study, a full-length CaM cDNA was isolated from the pearl oyster (Pinctada fucata). The oyster calmodulin encodes a 16.8 kDa protein which shares high similarity with vertebrate calmodulin. The oyster CaM mRNA shows the highest level of expression in the gill, a key organ involved in calcium uptake in oyster calcium metabolism. In situ hybridization results revealed that oyster CaM mRNA is expressed at the folds and the outer epithelial cells of the dorsal region of the mantle, suggesting that CaM is involved in regulation of calcium transport and secretion. Oyster CaM also showed a typical Ca2+ dependent electrophoretic shift characterization and calcium binding activity. Taken together, we have identified and characterized a pivotal calcium metabolism regulator of the oyster that may play an important role in regulation of calcium uptake, transport and secretion in the process of shell formation.

Amino Acid Sequence↗

PubMed2006

Effects of tributyltin on the energy metabolism of pen shell (Atrina pectinata japonica).

We examined the effects of tributyltin (TBT) on aerobic and anaerobic energy metabolism of pen shell (Atrina pectinata japonica). We exposed pen shells to TBT at nominal concentrations of 0 (control) and 1.0microg/l for 72h under aerobic condition. At the end of the exposure, half of the pen shells in each treatment were wrapped in plastic wrap to simulate exposure to hypoxia and held at 25 degrees C for another 12h. The concentrations of the products of energy metabolism, namely lactate, pyruvate, fumarate and succinate, in adductor muscle were measured. The exposure to TBT under aerobic condition significantly elevated lactate, pyruvate and fumarate concentrations (p<0.001). After subsequent exposure to anaerobic condition, the mean concentration of succinate in the TBT treatment group was 64% of that in the control group, but there were no significant differences. Our results suggest that the energy metabolism of pen shell is disrupted by exposure to TBT.

Aerobiosis↗

PubMed2005

The Akoya pearl oyster shell as an archival monitor of lead exposure.

The Akoya pearl oyster (Pinctada imbricata) was experimentally exposed to (a) constant levels of lead (Pb) at 180 microg L(-1) for nine weeks, or (b) two short term (pulse) exposures of Pb at 180 microg L(-1) (three weeks each) with an intervening depuration period (three weeks), to assess its utility as an (i) accumulative monitor of Pb contamination and an (ii) archival monitor for discriminating constant versus pulsed Pb exposure events. P. imbricata showed similar reductions in growth (based on shell morphology and wet weight) and Pb accumulation patterns for whole tissue and shell in response to both Pb exposure regimes. Thus the whole oyster was deemed an inappropriate accumulative monitor for assessing short-term temporal variation of Pb exposure and effect. However, using secondary ion mass spectrometry, Pb was shown to accumulate in the successively deposited nacreous layers of the shell of P. imbricata, documenting the exposure history of constant versus pulsed Pb events. Patterns of Pb deposition not only reflected the frequency of Pb exposure events but also their relative durations. Thus, the shell of P. imbricata may be employed as a suitable biological archive of Pb exposure.

Animals↗

PubMed2004

Preparation of multilayered gold-silica-polystyrene core-shell particles by seeded polymerization.

A preparation method for multilayered gold-silica-polystyrene core-shell composite particles is proposed. The gold-silica core-shell particles of 192-nm-sized, synthesized by coating the 18-nm-sized gold particles with silica by a seeded growth technique, were used as cores for succeeding polystyrene coating. After surface modification of gold-silica composite particles by methacryloxypropyltrimethoxysilane (MPTMS), polymerizations of styrene (0.16-0.4 M) were conducted with 8 x 10(-3) M of potassium persulfate initiator in the presence of 1 x 10(-3) M of sodium p-styrenesulfonate anionic monomer. Multilayered core-shell gold-silica-polystyrene particles that contained a single core could be obtained. The coefficient of variation of size distribution (CV) of the composite particles was less than 7%, and polystyrene shell thickness was in a range of 193 to 281 nm.

Gold↗

PubMed2005

Phase transfer of oleic acid capped Ni(core)Ag(shell) nanoparticles assisted by the flexibility of oleic acid on the surface of silver.

The phase transfer protocols in vogue for the oleic acid capped silver nanoparticles, viz., salt-induced precipitation and redispersion or phosphoric acid-induced method, are examined and compared thoroughly. A comprehensive evaluation with respect to the mechanistic aspects involved is made and the merits and demerits of the different procedures are delineated. It is found that the salt-induced precipitation and redispersion is more versatile in that the precipitate can actually be redispersed in both aqueous and organic media. However, in terms of mechanism both the routes seem to be very similar wherein the orientational change of oleic acid on the silver surface in the two different environments-organic and aqueous-plays a crucial role in the adaptability of the system to the different environments. Subsequently, this change of orientation of oleic acid on silver surface in aqueous and organic media has been utilized to phase transfer Ni-based nanoparticulate systems. The nascent oleic acid-capped Ni nanoparticles, which were synthesized by a foam-based protocol, were dispersible in water but not in nonpolar organic media such as cyclohexane or toluene. Then, just by coating a thin shell of silver on them we could achieve complete phase transfer of the Ni(core)Ag(shell) from aqueous to organic media following similar procedures used for oleic acid-capped silver nanoparticles. Here, the phase transfer seems to be facilitated by the orientational flexibility of oleic acid on the silver surface as opposed to other metal surfaces as evidenced from the infrared and thermogravimetric analyses of oleic acid-capped Ni and Ni(core)Ag(shell) nanoparticles. This orientation-assisted phase transfer method could be generalized and can be adapted to other systems where, if the nascent nanoparticles cannot be phase transferred as is, they can be coated by a silver shell and oleic acid making them suitable for dispersion in both aqueous and organic media.

Journal Article↗

PubMed2005

Magnetite nanoparticles with tunable gold or silver shell.

Fe3O4 nanoparticles with size approximately 13 nm have been prepared successfully in aqueous micellar medium at approximately 80 degrees C. To make Fe3O4 nanoparticles resistant to surface poisoning a new route is developed for coating Fe3O4 nanoparticles with noble metals such as gold or silver as shell. The shell thickness of the core-shell particles becomes tunable through the adjustment of the ratio of the constituents. Thus, the route yields well-defined core-shell structures of size from 18 to 30 nm with varying proportion of Fe3O4 to the noble metal precursor salts. These magnetic nanoparticles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), FTIR, differential scanning calorimetry (DSC), Raman and temperature-dependent magnetic studies.

Journal Article↗

PubMed2005

Synthesis of monodisperse fluorescent core-shell silica particles using a modified Stober method for imaging individual particles in dense colloidal suspensions.

Core-shell silica particles, with a diameter of 1.5 mum, containing a dye fluorescein isothiocyanate (FITC), are synthesized by the hydrolysis and condensation of tetraethylorthosilicate (TEOS). Sodium dodecyl sulfate (SDS) is added to synthesize fluorescent core particles with the diameter of approximately 1 mum. In the addition of SDS, the surface charge reduced by counterions (Na+) of the surfactant leads to a higher degree of aggregation of the primary particles and the formation of larger secondary particles. The particle growth kinetics confirms the aggregation growth model for the synthesis of monodisperse silica particles, and also shows the dependence of final particle size on colloidal stability resulting from the addition of SDS. Light and X-ray scattering data reveal that the final particles have compactly packed structures with smooth surfaces. The seeded growth technique is then used to form a silica shell layer on the fluorescent core. The added amount of water and NH4OH has significant effects on shell formation. Finally, the final core-shell silica particles are modified by chemisorption of octadecanol at the surface to be dispersed in organic solvents. Octadecyl-coated silica particles are sterically stabilized in silica index-matching solvents such as chloroform and hexadecane to directly image separate particles using confocal microscopy. In chloroform, the organophilic silica particles disperse well, whereas in hexadecane they form a volume-filling gel structure at room temperature.

Journal Article↗

PubMed2006

Synthesis and characterization of surface-enhanced Raman scattering tags with Ag/SiO2 core-shell nanostructures using reverse micelle technology.

A novel simplified method for synthesis of surface-enhanced Raman scattering tags has been reported. This synthesis method is based on reverse micelle technique using Igepal CO-520 as a surfactant and the mixed solution of silver nitrate and rhodamine dyes with isothiocyanate group as water pool followed by hydrazine hydrate reduction and TEOS polymerization leading to the formation of silica layer surrounding the silver core. Compared to the method reported in literature, the proposed methodology eliminates the necessity of vitrophilic pretreatment and makes it possible to complete all different processes including the preparation of silver nanoparticles, the conjugation of dye molecules and the formation of silica shell in the microreactor. The nanoparticle-based surface-enhanced Raman tags obtained are composed of silver core conjugated with rhodamine dyes and an encasing silica shell. Both the dyes themselves and the Ag/SiO2 core-shell nanoparticles without the encapsulation of dyes exhibit no Raman signals. However, the Ag/SiO2 core-shell nanoparticles exhibit strong Raman signals when encapsulated with these dyes. This is due to the appearance of fluorescence quenching and surface-enhanced Raman scattering effect resulting from the conjugation of dyes and silver core. The Raman tags were characterized using transmission electron microscopy (TEM), UV-visible absorption spectrometry, and Raman spectrometry.

Metal Nanoparticles↗

PubMed2006

Comparison of multiple shell vial cell lines for isolation of enteroviruses: a national perspective.

BACKGROUND: Isolation of enterovirus in cell culture is still utilized by clinical laboratories, for vaccine research, and for identifying serotypes for disease surveillance. Use of a combination of cell lines is recommended yet this practice has not been rigorously examined for shell vials. OBJECTIVES: To evaluate the growth predilection of enterovirus serotypes for certain shell vial cell lines in clinical samples received at a national reference laboratory. STUDY DESIGN: We retrospectively reviewed results of samples submitted for viral culture over a 3-year period. PMK, BGM, RD, A549, and MRC-5 cell lines grown in shell vials were inoculated and serotyped. RESULTS: Of 55,816 cultures, 1047 (1.9%) yielded enterovirus representing 18 serotypes. Echovirus 7, echovirus 9, and echovirus 30 were the most common serotypes recovered in 2002, 2003, and 2004, respectively. PMK and MRC-5 recovered the majority of enterovirus isolates; the addition of BGM and RD cells increased our recovery rate by 13%. For 52.6% of enteroviral isolates, cytopathic effect was found in only a single cell line. PMK and BGM cells were effective in isolating coxsackieviruses, and RD and MRC-5 were useful particularly in isolating echoviruses. CONCLUSIONS: A combination of shell vial cell lines is still recommended for recovery of enteroviruses.

Animals↗