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PubMed2000

Enhanced detection of respiratory syncytial virus by shell vial in children hospitalised with respiratory illnesses in northern Jordan.

During the period between November 1997 and May 1998, a total of 350 nasopharyngeal aspirates were obtained from children admitted to the Respiratory Disease Unit at Princess Rahma Hospital, northern Jordan, and diagnosed clinically as suffering from respiratory tract infections. Nasopharyngeal aspirates were investigated for the presence of respiratory syncycial virus (RSV) by using shell vial (SV) culture assay, conventional culture assay, and direct immunofluorescence assay. Out of 350 nasopharyngeal aspirates, 101(28.9%) were found positive by any of SV, conventional culture, and immunofluorescence; 91 (90.1%) by SV, 87(86.1%) by culture, and 83(82.2%) by immunofluorescence. The maximum number of virus isolations was noted in children below the age of 1 year and was associated with bronchiolitis. SV assay showed the highest sensitivity (94.3%) and specificity (96.9%) for detecting RSV from nasopharyngeal aspirates. These results emphasise the importance of SV culture assay for diagnosis of RSV, although immunofluorescence is a valuable, rapid diagnostic assay.

Age Distribution↗
PubMed2002

Enantioselective binding and stable encapsulation of alpha-amino aids in a helical poly(L-glutamic acid)-shelled dendrimer in aqueous solutions.

A novel water-soluble peptide-shelled dendrimer containing a poly(L-glutamic acid) segment grafted on the third-generation poly(amido amine) dendrimer was successfully synthesized, and its secondary structural properties and interaction with alpha-amino acids (Trp, Phe, and Tyr) were revealed by spectroscopic measurements. In the lower pH region, this peptide-dendrimer adopted an alpha-helix conformation with almost 100 % helicity resulting from the three-dimensional aggregation of the segment. Interactions with alpha-amino acids proceeded with positive cooperativity on the basis of a Hill plot, and as a result, D isomers preferentially bound to the alpha-helical segments relative to L isomers. The bound alpha-amino acids were not released into the water phase but were transferred into the inner core of the dendrimer where they remained stable, even when a conformational change of the helix segment was caused by pH variation.

Amino Acids↗
PubMed2001

Polycationic (mixed) core-shell dendrimers for binding and delivery of inorganic/organic substrates.

The convergent synthesis of a series of polycationic aryl ether dendrimers has been accomplished by a convenient procedure involving quantitative quaternarization of aryl(poly)amine core molecules. The series has been expanded to the preparation of the first polycationic, mixed core-shell dendrimer. All these dendrimers consist of an apolar core with a peripheral ionic layer which is surrounded by a less polar layer of dendritic wedges. These cationic, macromolecular species have been investigated for their ability to form assemblies with (anionic) guest molecules. The results obtained from UV/Vis and NMR spectroscopies, and MALDI-TOF-MS demonstrate that all the cationic sites throughout the dendrimer core are involved in ion pair formation with anionic guests giving predefined guest/host ratios up to 24. The large NMR spectroscopic shifts of resonances correlated with the groupings located in the core of the dendrimers, together with the relaxation time data indicate that the anionic guests are associated with the cationic core of these dendrimers. The X-ray molecular structure of the octacationic, tetra-arylsilane model derivative [Si(C6H3[CH2NMe3](2)-3,5)4]8+. 8I- shows that the iodide counterions are primarily located near the polycationic sphere. The new polycationic dendrimers have been investigated for their catalytic phase-transfer behavior and substrate delivery over a nanofiltration membrane.

Journal Article↗
PubMed2002

Valence-shell charge concentrations and electron delocalization in alkyllithium complexes: negative hyperconjugation and agostic bonding.

In this paper we present the results of density functional theory (DFT) calculations on the ethyl ligand and some related organic moieties; we then proceed to consider a range of alkyllithium complexes studied by DFT calculations and high-resolution X-ray and neutron diffraction. Topological analysis of the charge density is used to follow changes in the electronic structure of the organic fragment. The charge concentrations (CCs) in the valence shell at the alpha and beta atoms reveal faithfully the delocalization of the lone pair at the Calpha atom or of the Li-C bonding electrons. Negative hyperconjugation is thus shown to arise from delocalization of the lone pair or the Li-C bonding electrons over the alkyl fragment, with depletion of the metal-directed charge concentration at Calpha, and characteristic ellipticity profiles for the bonds involved in hyperconjugative delocalization. In the case of so-called lithium agostic complexes, we show that close Li.H contacts are a consequence of this delocalization and further secondary interactions, with Li.H-C agostic interactions, playing only a minor role. The ellipticity profiles and the magnitude of the CCs at Calpha provide a quantitative measure of the extent of delocalization, and show excellent agreement between experiment and theory.

Journal Article↗
PubMed2002

Assembly of hydrophobic shells and shields around lanthanides.

Luminescent lanthanide complexes have been developed, based on the assembly of bulky ligands around the lanthanide ion, to provide shell-type protection of the ion from coordinated solvent molecules. Aryl-functionalised imidodiphosphinate ligands (tpip and Metpip) provide a bidentate anionic site that leads to hexa-coordinate lanthanide complexes in which the aryl groups surround the ion. There are twelve phenyl groups around the lanthanide that act as "remote" (from the binding site) sensitisers for the metal ion. It is shown that these ligands are suitable for sensitising luminescence for all the lanthanides that emit in the visible range, namely, SmIII, EuIII, TbIII, DyIII. A "builtin" shield on the ligand is designed to provide a complete block of the approach of water to the lanthanide ion. The synthesis of the ligands and their lanthanides complexes as well as detailed photophysical studies of the complexes in solution and in the solid-state are presented.

Journal Article↗
PubMed2003

Mollusk shell acidic proteins: in search of individual functions.

Acidic proteins play a major role in the biomineralization process. These proteins are generally thought to control mineral formation and growth. Thus, characterization of individual acidic proteins is important as a first step toward linking function to individual proteins, which is our ultimate goal. In order to characterize the protein(s) responsible for the assemblage of biominerals, a new gel electrophoresis fixing and staining protocol was developed and many, if not all of the acidic proteins were visualized on the gel for the first time. In an in vitro assay we show that proteins extracted from an aragonitic shell layer induce the formation of amorphous calcium carbonate prior to its transformation into the aragonitic crystalline form. This study removes some major obstacles in the characterization of acidic proteins and sheds more light on the functions of these proteins in the biomineralization process.

Animals↗
PubMed2005

Valence shell charge concentrations at pentacoordinate d0 transition-metal centers: non-VSEPR structures of Me2NbCl3 and Me3NbCl2.

The molecular structures of the monomeric, pentacoordinated methylchloroniobium(IV) compounds Me3NbCl2 and Me2NbCl3 have been determined by gas electron diffraction (GED) and density functional theory (DFT) calculations, and, for Me3NbCl2, by single crystal X-ray diffraction. Each of the molecules is found to have a heavy-atom skeleton in the form of a trigonal bipyramid (TBP) with Cl atoms in the axial positions, in accord with their vibrational spectra. The TBP is somewhat distorted in the case of Me2NbCl3 with the two axial Nb--Cl bonds bent away from the equatorial, slightly shorter Nb--Cl bond. In the case of Me3NbCl2, moreover, the X-ray model suggests structural distortions away from the idealized C3h geometry, in line with the results of quantum chemical calculations. Structure optimizations by DFT calculations and least-squares refinement to the GED data yield the following structural parameters (calcd/exptl; eq=equatorial; ax=axial; distances in A, angles in degrees; average values in brackets): Me3NbCl2, in C(3v) symmetry, Nb--Cl 2.370/2.319(3), Nb--C 2.173/2.152(4), C--H 1.096/1.124(5), angle-spherical NbCH 109.3/105.2(8), angle-spherical ClNbC 92.2/93.3(2), angle-spherical CNbC 119.9/119.7(1); Me2NbCl3, in C(2v) symmetry, Nb--Cl(ax) 2.361/2.304(5), Nb--Cl(eq) 2.321/2.288(9), Nb--C 2.180/2.135(9), C--H 1.094/1.12(1), angle-spherical Cl(ax)NbCl(eq) 98.5/96.5(6), angle-spherical CNbC 121.0/114(2), angle-spherical NbCH 108.9/109(2). The electronic structures of Me2NbCl3 and Me3NbC(2 have been explored by rigorous analysis of both the wavefunction and the topology of the electron density, employing DFT calculations. Hence the structures of these compounds are shown to reflect repulsion between the Nb--C and Nb--Cl bonding electron density and charge concentrations induced by the methyl ligands in the valence shell of the Nb atom and arising mainly from use of Nb(4d) functions in the Nb--C bonds.

Journal Article↗
PubMed2006

Fluorogenic 1,3-dipolar cycloaddition within the hydrophobic core of a shell cross-linked nanoparticle.

Using either nitroxide mediated polymerization (NMP) or reversible addition fragmentation transfer (RAFT) techniques, novel block copolymers that present terminal acetylenes, in the side chain of the styrenic block, were obtained with narrow polydispersities and targeted molecular weights. For the conversion of these acetylene-functionalized polymers to amphiphilic block copolymers, RAFT techniques were preferred. Mild protection/deprotection chemistries were employed which were compatible with the incorporation of the acetylene functionality in the hydrophobic segment. These acetylene-functionalized, Click-readied amphiphilic block copolymers were then self-assembled and cross-linked to afford shell cross-linked knedel-like (SCK) nanoparticles that contained acetylene groups in the core domain. The hydrodynamic diameters (D(h)) of the block copolymer micelles and nanoparticles were determined by dynamic light scattering (DLS), and the dimensions of the nanoparticles were characterized using tapping-mode atomic force microscopy (AFM) and transmission electron microscopy (TEM). The chemical availability of the Click functionality within the core domain of the SCKs was investigated using the copper(I)-catalyzed 1,3-dipolar fluorogenic cycloaddition with a non-fluorescent 3-azidocoumarin profluorophore to afford intensely fluorescent nanoparticles.

Acrylic Resins↗
PubMedDate not supplied

Characterization of the in vitro adherence behavior of ultrasound responsive double-shelled microspheres targeted to cellular adhesion molecules.

We have developed novel adhesion molecule-targeted double-shelled microspheres which encapsulate nitrogen. We report in vitro targeting studies utilizing these microspheres conjugated to target-specific antibodies directed towards ICAM-1 and VCAM-1. In static adherence experiments, the adherence patterns of microspheres conjugated to three different monoclonal antibodies (two targeted to ICAM-1 and one to VCAM-1) to their target surfaces were very different. Maximum microsphere adherence at the lowest target and/or ligand densities was observed with the VCAM-1 system. Differences in target-specific adherence were also observed between anti-ICAM-1 and anti-VCAM-1 microsphere conjugates in flow adherence studies. Equilibrium binding studies of the target proteins in solution to the microsphere-bound ligands showed that the affinity constants of two microsphere-bound monoclonal antibodies for their target proteins are similar. Thus, ligand-target affinity is not the only determinant of microsphere adherence to the target surface in our systems. Shear stress was found to have an effect on the mean diameter of adhered microspheres; a decrease in the mean diameter with increasing shear was observed. The magnitude of this effect was dependent on both microsphere-bound ligand and target surface densities, with a more pronounced change at lower densities. Adhered microspheres were readily detectable using ultrasound at the lowest tested surface density of 40 mm(-2).

Adhesiveness↗
PubMed2002

Origin of the dopaminergic innervation of the central extended amygdala and accumbens shell: a combined retrograde tracing and immunohistochemical study in the rat.

The origin of the dopaminergic innervation of the central extended amygdala (EAc; i.e., the lateral bed nucleus of the stria terminalis [BSTl]-central amygdaloid nucleus [Ce] continuum) and accumbens shell (AcSh) was studied in the rat by combining retrograde transport of Fluoro-Gold (FG) with tyrosine hydroxylase (TH) immunofluorescence. Perikaryal profiles (PP) immunoreactive to FG and to both FG and TH were counted in A8-A14 dopaminergic districts. Our results suggest that dopaminergic inputs to the EAc and AcSh arise from the ventral tegmental area-A10, substantia nigra, pars compacta-A9, and retrorubral nucleus-A8 groups as well as from the dorsal raphe nucleus and periaqueductal gray substance, housing the dorsocaudal part of A10 group (A10dc). Quantitative estimates reveal that the A10dc group contains approximately half of the total number of FG/TH double-labeled PP projecting to Ce and BSTl. By using an anti-dopamine serum, DR/PAG projections to Ce were confirmed to be in part dopaminergic. In contrast, modest numbers of FG/TH double-labeled PP were seen in the A10dc group after injections in the sublenticular extended amygdala, interstitial nucleus of the posterior limb of the anterior commissure or AcSh. Ventral mesencephalic projections to the EAc display a crude mediolateral topographic organization, whereas those to the AcSh are topographically organized along a mediolateral and an inverted dorsoventral dimension. The diencephalic dopaminergic groups do not innervate the EAc or AcSh, except for the periventricular gray-A11 which sends light dopaminergic projections to Ce and BSTl. Overall, the present results provide additional details on the organization of the mesolimbic dopaminergic system that critically controls behavioral responsiveness to salient environmental stimuli.

Afferent Pathways↗
PubMed2003

Projections from the paraventricular nucleus of the thalamus to the rat prefrontal cortex and nucleus accumbens shell: ultrastructural characteristics and spatial relationships with dopamine afferents.

The paraventricular nucleus of the thalamus (PVT) participates in the functional integration of limbic cortical and striatal circuitry. In the rat, the PVT projects to the deep layers of the medial prefrontal cortex (PFC) and to the shell of the nucleus accumbens (NAc). However, the synaptic organization of PVT afferents within these regions remains undescribed. Furthermore, although dopamine (DA) modulates excitatory glutamate transmission in both areas, possible anatomic substrates for specific DA modulation of PVT inputs have not yet been investigated. To address these issues, immunoperoxidase labeling for tyrosine hydroxylase (TH) in DA axons was combined with anterograde tract-tracing, either by biotinylated dextran amine (BDA) labeled with immunogold-silver or by degeneration after lesions of the PVT. In both regions, and with either tracing method, PVT terminals formed primarily asymmetric axospinous synapses; in the NAc, a proportion of PVT terminals also synapsed onto dendrites. PVT profiles in both regions were often seen in direct apposition to TH-immunoreactive axons; this association was more evident in the NAc where the DA innervation is denser. Within the PFC, PVT profiles and TH-labeled axons were occasionally apposed to the same dendrites, but synaptic specializations were not typically seen at these seeming points of convergence. Within the NAc, PVT profiles occasionally made synapses onto spines and distal dendrites that received convergent synapses from TH-immunoreactive varicosities. These findings represent the first demonstration of postsynaptic convergence between DA and thalamic afferents to a striatal region and are consistent with direct synaptic modulation of PVT transmission by DA in the NAc but not the PFC.

Afferent Pathways↗
PubMed2006

Spectroscopy and femtosecond dynamics of type-II CdTe/CdSe core-shell quantum dots.

Syntheses of CdTe/CdSe type-II quantum dots (QDs) using CdO and CdCl2 as precursors for core and shell, respectively, are reported. Characterization was made via near-IR interband emission, transmission electron microscopy (TEM), energy dispersive spectroscopy (EDX), and X-ray diffraction (XRD). Femtosecond fluorescence upconversion measurements on the relaxation dynamics of the CdTe core (in CdTe/CdSe) emission and CdTe/CdSe interband emission reveal that as the size of the core increases from 5.3, 6.1 to 6.9 nm, the rate of photoinduced electron separation decreases from 1.96, 1.44 to 1.07 x10(12) s(-1). The finite rates of the initial charge separation are tentatively rationalized by the small electron-phonon coupling, causing weak coupling between the initial and charge-separated states.

Journal Article↗
PubMed2006

Properties of hydration shells of protein molecules at their pressure- and temperature-induced native-denatured transition.

Properties of water at the surface of biomolecules are important for their conformational stability. The behaviour of hydrating water at protein transition (t) pressures P(t) and temperatures T(t) , with the points (P(t),T(t) ) lying in the Native-Denatured (N-D) transition line, is studied. Hydration shells at the hydrophilic regions of protein molecules with surface charge density sigma are investigated with the help of the equation of state of water in an open system. The local values of sigma rather close to each other (sigma(D) approximately 0.3 C m(-2)) are found for six different experimental lines of the N-D transition found in the literature. The values sigma(D) correspond to the crossings of the total pressure (P(t)+Pi) vs sigma isotherms at different T(t) (Pi-electrostriction pressure). The pressures P(t) and temperatures T(t) appear to be related with some selected sites at the surfaces of the protein molecules.

Pressure↗
PubMed2007

Spatial relationship of source localizations in patients with focal epilepsy: Comparison of MEG and EEG with a three spherical shells and a boundary element volume conductor model.

Epilepsy surgery is an option for patients with pharmacoresistant focal epilepsies, but it requires a precise focus localization procedure. Magnetoencephalography (MEG) and electroencephalography (EEG) can be used for analysis of interictal activity. The aim of this prospective study was to compare clusters of source localization results with MEG and EEG using a three spherical shells (3SS) and a boundary element method (BEM) volume conductor model. The study was closed when 100 patients met the inclusion criteria. Simultaneous MEG and EEG were recorded during presurgical evaluation. Epileptiform signals were analyzed using an equivalent current dipole model. Centroids of source localizations from MEG, EEG, 3SS, and BEM in their respective combinations were compared. In a 3SS model, MEG source localizations were 5.6 mm inferior to those obtained by EEG, while in a BEM model MEG source localizations were 6.3 mm anterior and 4.8 mm superior. The mean scattering of source localizations between both volume conductor models was 19.5 mm for EEG and 9.6 mm for MEG. For MEG no systematic difference between BEM and 3SS source localizations was found. For EEG, source localizations with BEM were 5.9 mm posterior and 11.7 mm inferior to those determined using 3SS. No differences were found between the 46 temporal and the 54 extratemporal lobe epilepsy patients. The observed systematic differences of source localizations of epileptic spikes due to the applied source signal modality and volume conductor model should be considered in presurgical evaluation when only one source signal and volume conductor model is available.

Adult↗
PubMed2003

Vertical spectrum of the C2H2+ system. An open shell (SC)2-CAS-SDCI study.

The open shell (SC)(2)-CAS-SDCI method along with a basis set of atomic natural orbitals (ANO) has been applied for calculating the main ionization potentials of acetylene, as well as the manifold of excited states of the different symmetries up to 32 eV. In this method, the single and double excitations of a CAS space are generated and the corresponding CI matrix is corrected by means of the (SC)(2) procedure that cancels the size-extensivity error and adds some high order contributions. The mean absolute error for the outer-valence X (2)Pi(u)(1pi(u) (-1)), A (2)Sigma(g) (+)(3sigma(g) (-1)), and B (2)Sigma(u) (+)(2sigma(u) (-1)) states, and the inner-valence C (2)Sigma(g) (+)(2sigma(g) (-1)) state is 0.1 eV. The excited states of C(2)H(2) (+) corresponding to the Sigma(g) (+), Sigma(u) (+), Pi(g), Pi(u), Delta(g), and Delta(u) symmetries are reported and their composition is discussed. The results are thoroughly compared to the best available multireference CI calculations. Recent multichannel CI results by Wells and Lucchese [J Chem Phys 1999, 110, 6365] have been used also as a guide for the discussion of the results. Discrepancies in the description of many multiconfigurational states by means of the (SC)(2)-CAS-SDCI wave function as compared to previous large MR-CI calculations are significant and are, consequently, remarked on. A large mixing of the 3sigma(g) (-1) and 2sigma(g) (-1) processes is found in the A (2)Sigma(g) (+) and C (2)Sigma(g) (+) states, provided that the basis set is augmented with Rydberg functions.

Journal Article↗
PubMed2006

Ultrastructure of cyst shell and underlying membranes of three strains of the brine shrimp Artemia (Branchiopoda: Anostraca) from South India.

The cyst of Artemia has shell and membranous coverings over the embryo. The membranous coverings have special adaptive features to allow the physical changes accompanying repeated hydration and dehydration cycles that might occur and adversely influence postembryonic development. Whole and slices of cryptobiotic cysts were processed for electron microscopy to study the internal details and to compare the morphological architecture of three Artemia strains of South India. Surface topography of scanning electron microscopic (SEM) studies revealed distinct button shaped structures on the cyst of Puthalam strain. Transmission electron microscopic (TEM) studies of the cysts displayed the conventional pattern of anostracan crustaceans with outer cortex and alveolar layer, cuticular membranes, and the cytoplasmic inclusions namely nucleus, yolk droplets, lipoid bodies, and mitochondria. The prominent wavy outer cortex layer of Puthalam cysts corroborates the results of SEM studies.

Animals↗
PubMed2003

Oviductal sperm storage structure and their changes during the seasonal (dissociated) reproductive cycle in the soft-shelled turtle Lissemys punctata punctata.

The oviduct of the Indian fresh water soft-shelled turtle Lissemys punctata punctata was examined throughout the year under light and scanning electron microscopes to determine the location, histomorphological characteristics, and function of sperm storage structure, as well as their changes at different phases of the seasonal reproductive cycle. Sperm storage structures in the form of tubules were observed in the wall of isthmus throughout the year. These tubules developed either by folding or fusion of the oviductal mucosal folds and were lined by both ciliated and nonciliated epithelial cells. The height and secretory activities of the epithelia were markedly high during the breeding phase (August to September) but low in the nonbreeding phase (October to June). A few short tubules lined by cuboidal epithelium appear in the wall of infundibulum only during the breeding phase. Following mating (May), inseminated sperm were stored within the tubules of isthmus up to the pre-ovulatory stage (August). Thereafter, sperm associated with PAS-positive materials secreted from the epithelium (referred to as a carrier matrix) moved forward to the infundibulum and were stored within the storage tubules of the infundibulum for a short time. Subsequently, sperm evacuated the storage tubules and entered the oviductal lumen to fertilize the subsequently ovulated eggs during or prior to ovulation. The isthmus-tubules become shorter and narrower in the regressive phase (October to November) and remained so until the early preparatory phase (April). Sperm release might have been stimulated by estrogen secreted from the ovarian follicles of pre-ovulatory turtles. Stored sperm not utilized for fertilization remained viable not less than six months in the present turtle species.

Animals↗
PubMed2006

Nitrogen metabolism and excretion in the aquatic chinese soft-shelled turtle, Pelodiscus sinensis, exposed to a progressive increase in ambient salinity.

This study aimed to determine effects of 6-day progressive increase in salinity from 1 per thousand to 15 per thousand on nitrogen metabolism and excretion in the soft-shelled turtle, Pelodiscus sinensis. For turtles exposed to 15 per thousand water on day 6, the plasma osmolality and concentrations of Na+, Cl- and urea increased significantly, which presumably decreased the osmotic loss of water. Simultaneously, there were significant increases in contents of urea, certain free amino acids (FAAs) and water-soluble proteins that were involved in cell volume regulation in various tissues. There was an apparent increase in proteolysis, releasing FAAs as osmolytes. In addition, there might be an increase in catabolism of certain amino acids, producing more ammonia. The excess ammonia was retained as indicated by a significant decrease in the rate of ammonia excretion on day 4 in 15 per thousand water, and a major portion of it was converted to urea. The rate of urea synthesis increased 1.4-fold during the 6-day period, although the capacity of the hepatic ornithine urea cycle remained unchanged. Urea was retained for osmoregulation because there was a significant decrease in urea excretion on day 4. Increased protein degradation and urea synthesis implies greater metabolic demands, and indeed turtles exposed to 15 per thousand water had significantly higher O2 consumption rate than the freshwater (FW) control. When turtles were returned from 15 per thousand water to FW on day 7, there were significant increases in ammonia (probably released through increased amino acid catabolism) and urea excretion, confirming that FAAs and urea were retained for osmoregulatory purposes in brackish water.

Amino Acids↗