Phosphorylcholine-Primed Dendritic Cells Aggravate the Development of Atherosclerosis in ApoE-/- Mice

Background: Atherosclerosis is an inflammatory disease involving activation of adaptive and innate immune responses to antigens, including oxidized low-density lipoprotein (oxLDL) and phosphorylcholine (PC). Dendritic cells (DCs), which are antigen-presenting cells that activate T cells, are present in atherosclerotic lesions and are activated in immune organs. However, the mechanism by which PC promotes atherosclerosis is unclear.

Methods and Results: To evaluate whether PC promotes atherosclerosis via DCs, 2×10⁵ DCs activated by PC-keyhole limpet hemocyanin (DCs+PC-KLH) were injected into ApoE^−/− mice and the features of the plaques and the effects of the DCs on cellular and humoral immunity against PC-KLH were determined. Mice injected with DCs+PC-KLH had significantly larger atherosclerotic lesions than controls, with increased inflammation in the lesions and plaque instability. Furthermore, DCs+PC-KLH were characterized using flow cytometry after coculture of bone marrow-derived DCs and naïve T cells. DCs+PC-KLH showed an inflammatory phenotype, with increased CD86, CD40, and major histocompatibility complex Class II molecules (MHC-II), which promoted PC-specific T helper (Th) 1 and Th17 cell differentiation in vivo and in vitro. Moreover, 2 weeks after the administration of DCs+PC-KLH to mice, these mice produced PC- and oxLDL-specific IgG2a, compared with no production in the controls.

Conclusions: These findings suggest that DCs presenting PC promote specific immunity to PC, increase lesion inflammation, and accelerate atherosclerosis, which may explain how PC promotes atherosclerosis.

Blocking of the human ether-à-go-go-related gene channel by imatinib mesylate

Imatinib mesylate (IM), a widely prescribed powerful tyrosine kinase inhibitor, has been associated with increased risk of heart failure and is known to induce cell apoptosis and death in isolated cardiomyocytes. In addition to acquired long QT syndrome, pharmacological inhibition of human ether-à-go-go-related gene (HERG) channel has been reported to involve in apoptosis. The present study was undertaken to characterize the biophysical properties of IM on HERG and the molecular determinants of HERG blockade using mutant channels (Y652A and F656A). Wild type (WT) and mutant HERG channels were expressed in HEK-293 cells and Xenopus oocytes and the currents (I(HERG)) were measured using patch-clamp and two-microelectrode voltage-clamp techniques. IM inhibited WT I(HERG) in a concentration-dependent manner with an IC(50) of 19.51±2.50 µmol/L and 44.76±1.54 µmol/L in HEK-293 cells and Xenopus oocytes, respectively. The IM-induced inhibition of WT I(HERG) followed a voltage- and time-dependent manner. The blockade was enhanced by further activation of currents, which were in accordance with an open-channel blockade. The V(1/2) for steady-state activation shifted from -15.48±1.21 to -26.66±2.98 mV (p<0.05, n=6). The inactivation kinetics and voltage dependence of steady-state inactivation of the WT HERG channel were not significantly altered by IM. Two S6 domain mutants, F652A and Y656A, attenuated IM-induced inhibition of WT I(HERG). Therefore, IM preferentially blocked the open HERG channel through F652 and Y656, providing a molecular mechanism for the cardiac side effects during the clinical administration of IM.

Random blinded rechecking of sputum acid-fast bacilli smear using fluorescence microscopy: 8 years' experience

BACKGROUND

The Hong Kong TB Reference Laboratory is a high volume laboratory examining around 400 sputum acid-fast bacilli smears daily using fluorescence microscopy (FM).

OBJECTIVE

To assess the effectiveness of blinded rechecking applied to FM in a high-throughput laboratory.

METHOD

From 2003, 2.5% (5% in 2003 and 2004) of all smears were randomly selected, relabelled and assigned to each technician (rechecker) in turn. These smears were restained and re-examined. Discordance between initial screener and rechecker was resolved by a controller.

RESULTS

From 2003 to 2010, low false-negative (LFN) errors (0.10-0.27%) were within the critical values, at 85% (1 year) and 90% (7 years) sensitivity. However, LFN error (0.28-0.62%) among recheckers was prominent. There were also low false-positive (LFP) cases (0.13-0.75%), but subsequent cultures showed these to be mycobacteria culture-positive. This relatively poor performance among the recheckers might be due to background fluorescence increase after restaining and/or inefficiency of the rechecking procedure.

CONCLUSION

In a high-throughput laboratory, blind rechecking is a good means of quality assurance. To minimise false LFP, problems due to restaining should be resolved before blinded rechecking can be generally applied in the field for FM where mycobacterial cultures are not routinely performed.

Tunable hybridization in metal nanoshell chains

We have studied the coupled surface plasmon (SP) modes in periodic metal nanoshell chains by including long range electromagnetic interactions. The eigen-decomposition method is used to analyze the dispersion and dissipation of the SP modes. The resulting band structure can be understood as a hybridization between a hole band and a particle band with a structurally tunable band gap in the middle of the first Brillouin zone. The mode quality, which is defined as the imaginary part of the generalized polarizability, increases as the shell thickness decreases. This indicates a larger energy loss and an increasing coupling between the bands. Through the manipulation of the band structures, the propagation of the coupled SP modes in the nanoshell chain can be controlled.

Optical negative refraction in ferrofluids with magnetocontrollability

We numerically demonstrate optical negative refraction in ferrofluids containing isotropic Fe3O4 nanoparticles, each having an isotropic Ag shell, in the presence of an external dc magnetic field H. The all-angle broadband optical negative refraction with magnetocontrollability arises from H-induced chains or columns. They result in hyperbolic equifrequency contour for transverse magnetic waves propagating in the system. The finite element simulations verify the analyses using the effective medium approximation. Experimental demonstration and potential applications are suggested and discussed.

Localization of the electric-field distribution in graded core-shell metamaterials

The local electric-field distribution has been investigated in a core-shell cylindrical metamaterial structure under the illumination of a uniform incident optical field. The structure consists of a homogeneous dielectric core, a shell of graded metal-dielectric metamaterial, embedded in a uniform matrix. In the quasistatic limit, the permittivity of the metamaterial is given by the graded Drude model. The local electric potentials and hence the electric fields have been derived exactly and analytically in terms of hypergeometric functions. Our results showed that the peak of the electric field inside the cylindrical shell can be confined in a desired position by varying the frequency of the optical field and the parameters of the graded profiles. Thus, by fabricating graded metamaterials, it is possible to control electric-field distribution spatially. We offer an intuitive explanation for the gradation-controlled electric-field distribution.

Electromagnetic transparency by coated spheres with radial anisotropy

We establish an account of electromagnetic scattering by coated spheres with radial dielectric and magnetic anisotropy. Within full-wave scattering theory, we show that the total scattering cross section Qs is strongly dependent on both the dielectric anisotropy and magnetic anisotropy. As a consequence, by a suitable adjustment of the radius ratio, one may make the anisotropic coated particle nearly transparent or invisible. In the quasistatic case, we take one step forward to derive the effective permittivity and permeability for the coated particle, and the near-zero scattering radius ratio can be well described within effective medium theory. To one's interest, the introduction of radial anisotropy is helpful to achieve better transparency quality such as a much smaller Qs and wider range of near-zero scattering ratio. Moreover, when the coated particle is anisotropic, the position of the near-zero scattering radius ratio can be tunable, resulting in a tunable electromagnetic cloaking.

Dielectrophoresis of an Inhomogeneous Colloidal Particle under an Inhomogeneous Field: A First-Principles Approach

In reality, colloidal particles often possess an arbitrary inhomogeneity profile. We present a first-principles approach to dielectrophoresis of such an inhomogeneous colloidal particle under an inhomogeneous field of an oscillating electric dipole moment. For numerical simulations, we treat the inhomogeneous particle as a specific graded one with a physically motivated dielectric model and conductivity profile. We find that both multipolar interactions and spatial fluctuations inside the particle can affect the dielectrophoretic spectrum of the particle significantly.

Dynamic effects on nonlinear alternating current responses in electrorheological fluids

By using a perturbation approach, we investigate dynamic effects on nonlinear alternating current (ac) responses in electrorheological (ER) fluids under an ac or direct current electric field. We show that the dynamic effect due to a shear flow, which exerts a torque on ER particles and thus leads to the rotation of the particles about their centers, plays a significant role in the responses. Our results can be well interpreted in the dielectric dispersion spectral representation, and they offer a convenient method to determine the relaxation time and rotation velocity of ER particles by measuring the nonlinear ac responses.

Application of bioreactor system for large-scale production of Eleutherococcus sessiliflorus somatic embryos in an air-lift bioreactor and production of eleutherosides

Embryogenic callus was induced from leaf explants of Eleutherococcus sessiliflorus cultured on Murashige and Skoog (MS) basal medium supplemented with 1 mg l(-1) 2,4-dichlorophenoxyacetic acid (2,4-D), while no plant growth regulators were needed for embryo maturation. The addition of 1 mg l(-1) 2,4-D was needed to maintain the embryogenic culture by preventing embryo maturation. Optimal embryo germination and plantlet development was achieved on MS medium with 4 mg l(-1) gibberellic acid (GA(3)). Low-strength MS medium (1/2 and 1/3 strength) was more effective than full-strength MS for the production of normal plantlets with well-developed shoots and roots. The plants were successfully transferred to soil. Embryogenic callus was used to establish a suspension culture for subsequent production of somatic embryos in bioreactor. By inoculating 10 g of embryogenic cells (fresh weight) into a 3l balloon type bubble bioreactor (BTBB) containing 2l MS medium without plant growth regulators, 121.8 g mature somatic embryos at different developmental stages were harvested and could be separated by filtration. Cotyledonary somatic embryos were germinated, and these converted into plantlets following transfer to a 3l BTBB containing 2l MS medium with 4 mg l(-1) GA3. HPLC analysis revealed that the total eleutherosides were significantly higher in leaves of field grown plants as compared to different stages of somatic embryo. However, the content of eleutheroside B was highest in germinated embryos. Germinated embryos also had higher contents of eleutheroside E and eleutheroside E1 as compared to other developmental stages. This result indicates that an efficient protocol for the mass production of E. sessiliflorus biomass can be achieved by bioreactor culture of somatic embryos and can be used as a source of medicinal raw materials.

Spectral representation of the effective dielectric constant of graded composites

We generalize the Bergman-Milton spectral representation, originally derived for a two-component composite, to extract the spectral density function for the effective dielectric constant of a graded composite. This work has been motivated by a recent study of the optical absorption spectrum of a graded metallic film [Huang and Yu, Appl. Phys. Lett. 85, 94 (2004)] in which a broad surface-plasmon absorption band was shown to be responsible for enhanced nonlinear optical response and an attractive figure of merit. It turns out that, unlike in the case of homogeneous constituent components, the characteristic function of a graded composite is a continuous function because of the continuous variation of the dielectric function within the constituent components. Analytical generalization to three-dimensional graded composites is discussed, and numerical calculations for multilayer composites are given as a simple application.

Macrophage-stimulating activity of exo-biopolymer from cultured rice bran with Monascus pilosus

To find a new use of rice bran, five fungi were examined for the production of exo-biopolymer with macrophage-stimulating activity from rice bran. Among the exo-biopolymers produced from the cultures, Monascus pilosus had the most potent macrophage stimulating activity in a liquid culture rather than in a solid culture. In order to improve the yield of exo-biopolymer with macrophage-stimulating activity, a suitable medium for exo-biopolymer was tested in submerged culture of M. pilosus. The highest amount of exo-biopolymer (13.9 mg/mL) was obtained in a medium containing rice bran as an only carbon source followed by media with additional maltose and sucrose (13.8 and 13.7 mg/mL, respectively). The addition of peptone resulted in the production of high amount of exo-biopolymer (15.1 mg/mL), meanwhile the addition of ammonium chloride resulted in 264.0 microg/mL of glucosamine content. Among eight different kinds of inorganic salts tested, potassium phosphate (0.1%) was the most effective inorganic salt for the mycelial growth and exo-biopolymer production. Therefore the optimal medium composition was as follows (g/L): 20 g of rice bran, 5 g of peptone, and 1 g of KH2PO4. The optimal culture pH and time for mycelial growth and exo-biopolymer production was pH 5.0 and 25 degrees C, respectively. The maximum exo-biopolymer (20.1 mg/mL) was observed at the fourth day of cultivation. Exo-biopolymer, a crude polysaccharide fraction, mainly contained neutral sugar (81.8%) with considerable amounts of uronic acid (18.2%). Component sugar analysis showed that the active fraction consisted mainly of arabinose, galactose, glucose, which was digested from starch of rice bran during cultivation, and uronic acid (molar ratio; 0.8:1.0:0.7:0.8).

Computed tomography for cervical spine trauma. The impact of MDCT on fracture detection and dose deposition

A multidetector computed tomography (MDCT) was installed in our department. Referral rates, examination protocols and detection rates of abnormal findings in CT examinations for cervical spine trauma 6 months before and 6 months after MDCT installation were compared to look for changes in practice. Retrospective analysis of all CT cervical spine examinations in patients with multiple trauma over two contiguous 6-month periods: from July 2003 to December 2003 (helical CT) and from January 2004 to June 2004 (MDCT). Variables recorded were number of CT examinations performed, scan plane coverage and traumatic abnormalities detected. Phantom dosimetry measurements for cervical spine examination in both helical CT and MDCT were compared. One hundred and fifty four patients underwent cervical spine CT during these periods. Helical CT period: of 91 patients undergoing CT cervical spine examination for trauma, 65 (71%) were complete cervical examinations and 26 (29%) were level-specific examinations. Eight patients (9%) had cervical spine fracture, six of which were apparent on radiographs. Dose estimations for thyroid, lens and breast were 24.76, 1.86 and 0.21 mGy, respectively, for complete cervical spine examinations. MDCT period: of 63 patients who underwent CT cervical spine examination for trauma, 61 (97%) were complete examinations and 2 (3%) were level-specific examinations. Six patients (11%) had cervical spine fracture, three of which were apparent on radiographs. Dose estimations for thyroid, lens and breast were 75.8, 9.7 and 0.7 mGy, respectively, for complete cervical spine examinations, which were notably higher than those for helical CT. After installation of MDCT, clinical requests for complete examination of the cervical spine following trauma increased. This changing trend resulted in a significantly higher radiation dose to thyroid, lens and breast.

Production of eleutherosides in in vitro regenerated embryos and plantlets of Eleutherococcus chiisanensis

High frequency somatic embryogenesis of Eleutheorcoccus chiisanensis was achieved through suspension culture of embryogenic cells in hormone-free Murashige and Skoog liquid medium supplemented with 30 g sucrose l-1. Cotyledonary somatic embryos were germinated and converted into plantlets using 20 microM: gibberellic acid which were then grown in a 10 l airlift bioreactor. HPLC analysis revealed the accumulation of eleutheroside B, E and E1 in the embryos and plantlets. Thus mass production of embryos and plantlets of E. chiisanensis can be achieved in liquid cultures and the biomass produced may become an alternative source of eleutherosides.

Second-harmonic generation in graded metallic films

We study the effective second-harmonic generation (SHG) susceptibility in graded metallic films by invoking the local field effects exactly and further numerically demonstrate that graded metallic films can serve as a novel optical material for producing a broad structure in both the linear and the SHG response and an enhancement in the SHG signal.

Theory of nondegenerate nonlinear optical susceptibilities of graded composites with high-volume fractions

We present a theory for the effective nondegenerate third-order nonlinear optical susceptibility (NDTNOS) of composite media in which the graded metallic particles with weak nonlinearity and the linear dielectric grains are randomly distributed. In combination with an effective medium approximation, the recently established nonlinear differential effective dipole approximation (NDEDA), which is valid for the degenerate third-order optical nonlinearity of the composites in the dilute limit, is generalized to deal with the effective NDTNOS of graded composites of high-volume fractions. Numerical results show that for high-volume fractions, the presence of gradation makes the effective NDTNOS enhanced, but the linear optical absorption reduced, thus, yielding an attractive figure of merit. In addition, by using NDEDA and Maxwell-Garnett approximation, we study the effective NDTNOS of the graded composite media with the Hashin-Shtrikman microgeometry. The nondegenerate optical nonlinearity enhancement is found to be sensitive to the composite topology.

Methyl jasmonate elicitation enhanced synthesis of ginsenoside by cell suspension cultures of Panax ginseng in 5-l balloon type bubble bioreactors

The effects of methyl jasmonate (MJ) elicitation on the cell growth and accumulation of ginsenoside in 5-l bioreactor suspension cultures of Panax ginseng were investigated. Ginsenoside accumulation was enhanced by elicitation by MJ (in the range 50-400 microM); however, fresh weight, dry weight and growth ratio of the cells was strongly inhibited by increasing MJ concentration. The highest ginsenoside yield was obtained at 200 microM MJ. In the second experiment, 200 microM MJ was added on day 15 during the cultivation. The ginsenoside, Rb group, and Rg group ginsenoside content increased 2.9, 3.7, and 1.6 times, respectively, after 8 days of MJ treatment. Rb group gisnsenosides accumulated more than Rg group ginsenosides. Among Rb group ginsenosides, Rb1 content increased significantly by four times but the contents of Rb2, Rc and Rd increased only slightly. Among Rg group ginsenosides, Rg1 and Re showed 2.3-fold and 3.0-fold increments, respectively, whereas there was only a slight increment in Rf group ginsenosides. These results suggest that MJ elicitation is beneficial for ginsenoside production using 5-l bioreactor cell suspension cultures.

Interparticle force in electrorheological solids: many-body dipole-induced dipole model

One often investigates electrorheological (ER) solids by using the point-dipole (PD) approximation, which, however, is known to err considerably for touching particles due to the existence of many-body (local-field) effects and multipolar interactions. Beyond the PD model, previous attempts have been restricted to either local-field effects only or multipolar interactions only, but not both. In the present work, we have developed a many-body dipole-induced dipole model for an ER solid the lattice structure of which can be changed due to the application of external fields, in an attempt to take into account both local-field effects and multipolar interactions. The results show that the multipolar interaction can indeed be dominant over the dipolar interaction, while the local-field effect may yield an important correction. Also, the results are well understood with the aid of spectral representation theory.

Nonlinear ac responses of electro-magnetorheological fluids

We apply a Langevin model to investigate the nonlinear ac responses of electro-magnetorheological (ERMR) fluids under the application of two crossed dc magnetic (z axis) and electric (x axis) fields and a probing ac sinusoidal magnetic field. We focus on the influence of the magnetic fields which can yield nonlinear behaviors inside the system due to the particles with a permanent magnetic dipole moment. Based on a perturbation approach, we extract the harmonics of the magnetic field and orientational magnetization analytically. To this end, we find that the harmonics are sensitive to the degree of anisotropy of the structure as well as the field frequency. Thus, it is possible to real-time-monitor the structure transformation of ERMR fluids by detecting the nonlinear ac responses.

Nonlinear alternating current responses of dipolar fluids

The frequency-dependent nonlinear dielectric increment of dipolar fluids in nonpolar fluids is often measured by using a stationary relaxation method in which two electric fields are used: The static direct current (dc) field of high strength causing the dielectric nonlinearity, and the probing alternating current (ac) field of low strength and high frequency. When a nonlinear composite is subjected to a sinusoidal electric field, the electric response in the composite will, in general, consist of ac fields at frequencies of higher-order harmonics. Based on the Fröhlich model, we present a theory to investigate the nonlinear ac responses of dipolar fluids containing both polarizable monomers and dimers. In the case of monomers only, our theory reproduces the known results. We obtain the fundamental, second-, and third-order harmonics of the Fröhlich field by performing a perturbation expansion. The even-order harmonics are induced by the coupling between the ac and dc fields, although the system under consideration has a cubic nonlinearity only. The harmonics of the Fröhlich field can be affected by the field frequency, temperature, dispersion strength, and the characteristic frequency of the dipolar fluid, as well as the dielectric constant of the nonpolar fluid. The results are found to be in agreement with recent experimental observations.

Dielectric behaviour of graded spherical cells with an intrinsic dispersion

The dielectric properties of single-shell spherical cells with an intrinsic dielectric dispersion have been investigated. By means of the dielectric dispersion spectral representation (DDSR) for the Clausius-Mossotti (CM) factor, we express the dispersion strengths as well as the characteristic frequencies of the CM factor analytically in terms of the parameters of the cell model. These analytic expressions enable us to assess the influence of various model parameters on the electrokinetics of cells. Various interesting behaviours have been reported. We extend our considerations to a more realistic cell model with a graded core, which can have spatial gradients in the conductivity and/or permittivity. To this end, we address the effects of a graded profile in a small-gradient expansion in the framework of DDSR.

Electrokinetic behavior of two touching inhomogeneous biological cells and colloidal particles: effects of multipolar interactions

We present a theory to investigate electrokinetic behavior, namely, electrorotation and dielectrophoresis under alternating current (ac) applied fields for a pair of touching inhomogeneous colloidal particles and biological cells. These inhomogeneous particles are treated as graded ones with physically motivated model dielectric and conductivity profiles. The mutual polarization interaction between the particles yields a change in their respective dipole moments, and hence in the ac electrokinetic spectra. The multipolar interactions between polarized particles are accurately captured by the multiple images method. In the point-dipole limit, our theory reproduces the known results. We find that the multipolar interactions as well as the spatial fluctuations inside the particles can affect the ac electrokinetic spectra significantly.

Nonlinear alternating current responses of graded materials

When a composite of nonlinear particles suspended in a host medium is subjected to a sinusoidal electric field, the electrical response in the composite will generally consist of alternating current (ac) fields at frequencies of higher-order harmonics. The situation becomes more interesting when the suspended particles are graded, with a spatial variation in the dielectric properties. The local electric field inside the graded particles can be calculated by the differential effective dipole approximation, which agrees very well with a first-principles approach. In this work, a nonlinear differential effective dipole approximation and a perturbation expansion method have been employed to investigate the effect of gradation on the nonlinear ac responses of these composites. The results showed that the fundamental and third-harmonic ac responses are sensitive to the dielectric-constant and/or nonlinear-susceptibility gradation profiles within the particles. Thus, by measuring the ac responses of the graded composites, it is possible to perform a real-time monitoring of the fabrication process of the gradation profiles within the graded particles.

Electrorotation in graded colloidal suspensions

Biological cells can be treated as composites of graded material inclusions. In addition to biomaterials, graded composites are important in more traditional materials science. In this paper, we investigate the electrorotation spectrum of a graded colloidal suspension in an attempt to discuss its dielectric properties. For that, we use the recently obtained differential effective dipole approximation and generalize it for nonspherical particles. We find that variations in the conductivity profile may make the characteristic frequency redshifted and have also an effect on the rotation peak. On the other hand, variations in the dielectric profile may enhance the rotation peak, but do not have any significant effect on the characteristic frequency. In the end, we apply our theory to fit experimental data obtained for yeast cells and find good agreement.

Pharmacological activities of stromata of Cordyceps scarabaecola

The chemical components of freeze-dried stromata from Cordyceps scarabaecola were examined. The stromata consisted of crude carbohydrates (55.1%) and crude proteins (14.2%). The stromata were also composed of a low content of crude ash (6.6%) and fat (1.5%). The composition of the carbohydrate in the stromata included a large quantity of glucose (46.6%), mannose (35.4%) and galactose (18.0%). The acidic amino acids such as glutamic acid (32.1 mg/g) and aspartic acid (24.7 mg/g) were present in a large quantity. The extracts of stromata did not reveal any inhibitory activity for AChE in vitro. It was observed that a hot-water extract (HW) of the stromata contributed significantly to the anticoagulant activity (60 s coagulating time) and anticomplementary activity (62% of ITCH50 value). The MeOH-soluble fraction (M) from the freeze-dried stromata inhibited TPA-induced O2- generation as effectively as the positive control, genistine 27%. The hot-water extract (HW) showed the most potent intestinal immune system modulation activity and the MeOH-soluble fraction (M) had intermediate activity.

Theory of ac electrokinetic behavior of spheroidal cell suspensions with an intrinsic dispersion

The dielectric dispersion, dielectrophoretic (DEP), and electrorotational (ER) spectra of spheroidal biological cell suspensions with an intrinsic dispersion in the constituent dielectric constants are investigated. By means of the spectral representation method, we express analytically the characteristic frequencies and dispersion strengths both for the effective dielectric constant and the Clausius-Mossotti factor (CMF). We identify four and six characteristic frequencies for the effective dielectric spectra and CMF, respectively, all of them being dependent on the depolarization factor (or the cell shape). The analytical results allow us to examine the effects of the cell shape, the dispersion strength, and the intrinsic frequency on the dielectric dispersion, DEP, and ER spectra. Furthermore, we include the local-field effects due to the mutual interactions between cells in a dense suspension, and study the dependence of co-field or antifield dispersion peaks on the volume fractions.

Dielectrophoresis of charged colloidal suspensions

We present a theoretical study of dielectrophoretic (DEP) crossover spectrum of two polarizable particles under the action of a nonuniform ac electric field. For two approaching particles, the mutual polarization interaction yields a change in their respective dipole moments, and hence, in the DEP crossover spectrum. The induced polarization effects are captured by the multiple image method. Using spectral representation theory, an analytic expression for the DEP force is derived. We find that the mutual polarization effects can change the crossover frequency at which the DEP force changes sign. The results are found to be in agreement with recent experimental observation and as they go beyond the standard theory, they help to clarify the important question of the underlying polarization mechanisms.

Ground state of a polydisperse electrorheological solid: beyond the dipole approximation

The ground state of an electrorheological (ER) fluid has been studied based on our recently proposed dipole-induced dipole (DID) model. We obtained an analytical expression of the interaction between chains of particles which are of the same or different dielectric constants. The effects of dielectric constants on the structure formation in monodisperse and polydisperse electrorheological fluids are studied in a wide range of dielectric contrasts between the particles and the base fluid. Our results showed that the established body-centered tetragonal ground state in monodisperse ER fluids may become unstable due to a polydispersity in the particle dielectric constants. While our results agree with that of the fully multipole theory, the DID model is much simpler, which offers a basis for computer simulations in polydisperse ER fluids.

Anti-stress and anti-fatigue effect of fermented rice bran

The anti-stress and anti-fatigue effects of a hot water extract of fermented rice bran (FRB) were investigated with Saccharomyces cerevisae IFO 2346 on rats or mice. Oral administration (1 g/kg/day) of a hot water extract of FRB inhibited major changes in weight of the adrenal, thymus, spleen and thyroid, showing the anti-stress effect. A hot water extract of FRB also inhibited the increase of GPT and LDH activity, cholesterol and serum glucose levels. Administration (1 g/kg/day) for 2 weeks significantly prolonged the swimming time, resulting in an increase of the anti-fatigue effect. From these results, it can be considered that FRB has an anti-stress and anti-fatigue effect.

Biological activities of Saccharomyces cerevisiae and fermented rice bran as feed additives

AIMS

The objective of the present study was to examine for the various biological activities for feed additives of Saccharomyces cerevisiae and fermented rice bran.

METHODS

The feed additives (100 g of each: YE, brewery yeast; PM, mixture of YE and SF; SF, fermented rice bran) were decocted with 2 l water at 100 degrees C to a half volume.

RESULTS

The hot-water extract of PM was found to increase the stimulation of the macrophage activation (2.0-fold) and the intestinal immune modulating activity (1.8-fold), compared with those of control. When the hot-water extracts of PM, SF and YE were fed to the rats for 8 d (1 g kg-1 d-1), PM and SF showed the more effective anti-stress effect on spleen, thyroid and thymus gland.

SIGNIFICANCE AND IMPACT OF THE STUDY

The hot-water extract of PM can have a significant impact on strengthening the living body's immune system and proliferating anti-stress activities with relation to enhance immunity.

Statistics of level spacing of geometric resonances in random binary composites

We study the statistics of level spacing of geometric resonances in the disordered binary networks. For a definite concentration p within the interval [0.2,0.7], numerical calculations indicate that the unfolded level spacing distribution P(t) and level number variance Sigma(2)(L) have general features. It is also shown that the short-range fluctuation P(t) and long-range spectral correlation Sigma(2)(L) lie between the profiles of the Poisson ensemble and Gaussion orthogonal ensemble. At the percolation threshold p(c), crossover behavior of functions P(t) and Sigma(2)(L) is obtained, giving the finite size scaling of mean level spacing delta and mean level number n, which obey the scaling laws, delta=1.032L(-1.952) and n=0.911L(1.970).

Electrorotation of a pair of spherical particles

We present a theoretical study of electrorotation (ER) of two spherical particles under the action of a rotating electric field. When the two particles approach and finally touch, the mutual polarization interaction between the particles leads to a change in the dipole moment of the individual particle and hence the ER spectrum, as compared to that of the well-separated particles. The mutual polarization effects are captured by the method of multiple images. From the theoretical analysis, we find that the mutual polarization effects can change the characteristic frequency at which the maximum angular velocity of electrorotation occurs. The numerical results can be understood in the spectral representation theory.

Relaxation of surface charge on rotating dielectric spheres: Implications on dynamic electrorheological effects

We have examined the effect of an oscillatory rotation of a polarized dielectric particle. The rotational motion leads to a redistribution of the polarization charge on the surface of the particle. We show that the time-averaged steady-state dipole moment is along the field direction, but its magnitude is reduced by a factor that depends on the angular velocity of rotation. As a result, the rotational motion of the particle reduces the electrorheological effect. We further assume that the relaxation of the polarized charge is arised from a finite conductivity of the particle or host medium. We calculate the relaxation time based on the Maxwell-Wagner theory, suitably generalized to include the rotational motion. Analytic expressions for the reduction factor and the relaxation time are given and their dependence on the angular velocity of rotation will be discussed.

Nonlinear ac response of anisotropic composites

When a suspension consisting of dielectric particles having nonlinear characteristics is subjected to a sinusoidal (ac) field, the electrical response will in general consist of ac fields at frequencies of the higher-order harmonics. These ac responses will also be anisotropic. In this work, a self-consistent formalism has been employed to compute the induced dipole moment for suspensions in which the suspended particles have nonlinear characteristics, in an attempt to investigate the anisotropy in the ac response. The results showed that the harmonics of the induced dipole moment and the local electric field are both increased as the anisotropy increases for the longitudinal field case, while the harmonics are decreased as the anisotropy increases for the transverse field case. These results are qualitatively understood with the spectral representation. Thus, by measuring the ac responses both parallel and perpendicular to the uniaxial anisotropic axis of the field-induced structures, it is possible to perform real-time monitoring of the field-induced aggregation process.

Computer simulations of electrorheological fluids in the dipole-induced dipole model

We have employed the multiple image method to compute the interparticle force for a polydisperse electrorheological (ER) fluid in which the suspended particles can have various sizes and different permittivities. The point-dipole (PD) approximation, being routinely adopted in the computer simulation of ER fluids, is known to err considerably when the particles approach and finally touch due to multipolar interactions. The PD approximation becomes even worse when the dielectric contrast between the particles and the host medium is large. From the results, we show that the dipole-induced-dipole (DID) model yields very good agreements with the multiple image results for a wide range of dielectric contrasts and polydispersity. As an illustration, we have employed the DID model to simulate the athermal aggregation of particles in ER fluids, both in uniaxial and rotating fields. We find that the aggregation time is significantly reduced. The DID model partially accounts for the multipolar interaction and is simple to use in the computer simulation of ER fluids.

Anti-stress and anti-fatigue effects of fermented rice bran

The anti-stress and anti-fatigue effects on rats and mice of a hot water extract of rice bran fermented with Saccharomyces cerevisae IFO 2346 were investigated. Oral administration (1 g/kg/day) of the hot water extract of fermented rice bran (FRB) inhibited major changes in the weight of the adrenal, thymus, spleen and thyroid, showing an anti-stress effect. The hot water extract of FRB also inhibited increases in the GPT and LDH activity, cholesterol and glucose in the serum. The administration (1 g/kg/day) for 2 weeks significantly prolonged the swimming time, resulting in an increase in the anti-fatigue effect. It is considered from these results that FRB had anti-stress and anti-fatigue effects.

Field-induced structure transformation in electrorheological solids

We have computed the local electric field in a body-centered tetragonal (bct) lattice of point dipoles via the Ewald-Kornfeld formulation, in an attempt to examine the effects of a structure transformation on the local-field strength. For the ground state of an electrorheological solid of hard spheres, we identified a different structure transformation from the bct to the face-centered cubic (fcc) lattices by changing the uniaxial lattice constant c under the hard-sphere constraint. In contrast to the previous results, the local field exhibits a nonmonotonic transition from bct to fcc. As c increases from the bct ground state, the local field initially decreases rapidly towards the isotropic value at the body-centered cubic lattice, decreases further, reaching a minimum value and increases, passing through the isotropic value again at an intermediate lattice, reaches a maximum value and finally decreases to the fcc value. An experimental realization of the structure transformation is suggested. Moreover, the change in the local field can lead to a generalized Clausius-Mossotti equation for the bct lattices.

Effective nonlinear optical properties of metal-dielectric composite media with shape distribution

The effective linear and nonlinear optical properties have been investigated in granular metal-dielectric composites taking the geometric shape of inclusions into account. Recently derived Maxwell-Garnett-type approximations are generalized to study the spectral function for composites in which the metal inclusions have a uniform distribution of geometric shapes. The numerical results show that the spectral density function becomes a prominent peak around small spectral value s within the non-self-consistent Maxwell-Garnett approximation but a broad continuous spectrum around large s besides the prominent peak around small s within the self-consistent Maxwell-Garnett approximation. Based on the spectral representation, we investigate the optical absorption and third-order nonlinear optical susceptibility. The results indicate that the shape distribution can lead to the separation of the nonlinearity enhancement peak from the absorption peak and thereby make the figure of merit more attractive.

Characteristics of patients with Burkholderia cepacia bacteremia

Burkholderia cepacia has become an important pathogen of infections in immunocompromised and nosocomial patients. The characteristics of 42 episodes of B. cepacia bacteremia in 40 patients admitted to the Taipei Veterans General Hospital between January 1997 and December 1999 were retrospectively analyzed. Factors that adversely influenced the mortality rate included respiratory failure, an unknown infection source, a period in an intensive care unit, and shock. Most of the patients had serious underlying diseases, such as diabetes mellitus, malignancy, congestive heart failure, and chronic obstructive pulmonary disease. The mean time for a positive blood culture was 45 days after admission. The overall mortality rate was 28.6% (12/42), and 44.4% (12/27) of all deaths were directly related to B. cepacia bacteremia. Polymicrobial bacteremia was found in 5 patients. Ceftazidime was the most effective antimicrobial agent in vitro, whereas chloramphenicol, imipenem, and trimethoprim/sulfamethoxazole were less effective alternatives. Appropriate antibiotic therapy was given to 30 patients, most of whom responded to the therapy except for 5 who died despite receiving appropriate treatment. Although B. cepacia infection develops in a relatively small proportion of hospitalized individuals, it has a major impact on morbidity and mortality. In view of the fact that B. cepacia develops resistance to a wide range of antimicrobial agents, ceftazidime and/or trimethoprim/sulfamethoxazole should be the drug of choice for empiric therapy.

Bacteremia after endoscopic injection of N-butyl-2-cyanoacrylate for gastric variceal bleeding

BACKGROUND

Cyanoacrylate may form a barrier that prevents bacterial invasion when used in tissue. Because cyanoacrylate polymerizes within seconds on contact with aqueous media, it is used worldwide to arrest gastric variceal bleeding. The aim of this study was to determine the frequency of bacteremia after endoscopic cyanoacrylate injection for gastric variceal bleeding.

METHODS

Patients with cirrhosis who underwent endoscopic cyanoacrylate injection for gastric variceal bleeding were included. Patients with cirrhosis who underwent upper endoscopy for nonvariceal upper GI bleeding were recruited as controls. Patients with infection before endoscopy were excluded. Blood was cultured in both groups. Injection needles and endoscope accessory channels were cultured in the cyanoacrylate injection group.

RESULTS

More patients injected with cyanoacrylate had positive blood cultures in comparison with the control group (15/47 vs. 1/47, p < 0.0001). In the cyanoacrylate injection group, the volume of blood transfused and Child-Pugh score were factors associated with the occurrence of bacteremia. Most episodes of bacteremia were transient, except for 1 patient who died of sepsis. Most of the microorganisms cultured from blood samples were identical to those cultured from injection needles (65%) and accessory channels (90%).

CONCLUSIONS

Endoscopic cyanoacrylate injection for gastric varices does not limit the spread of bacteria. The endoscope accessory channel was the major source of bacteria. Most episodes of bacteremia were transient and uneventful.

First-principle approach to dielectric behavior of nonspherical cell suspensions

We present a theoretical study of the dielectric behavior of cell suspensions by employing the Bergman-Milton spectral representation of the effective dielectric constant. By means of the spectral representation, we derive the dielectric dispersion spectrum in terms of the electrical and structure parameters of the cell models. Our results show that a better agreement with the experimental data can be obtained, provided that we introduce a conductivity contrast t=sigma(2)/(sigma(2)-sigma(1)). We find that the conductivity of the cell cytoplasm sigma(1) can be much larger than that of the suspending medium sigma(2), in contrast to the previous claim that sigma(1) approximately sigma(2).

Nonlinear ac response of an electrorheological fluid

The applied electric field used in most electrorheological (ER) experiments is usually quite high, and nonlinear ER effects have been measured recently. When a nonlinear ER fluid is subjected to a sinusoidal (ac) field, the electrical response will in general consist of ac fields at frequencies of the higher-order harmonics. In this paper, a self-consistent formalism has been employed to compute the induced dipole moment for ER fluids in which the suspended particles have nonlinear characteristics, in an attempt to investigate the ac response of a nonlinear ER fluid.

Purification and characterization of antithrombotics from Syzygium aromaticum (L.) MErr. & PERRY

Two antithrombotic polysaccharides with relatively high molecular weight (HMW) and low molecular weight (LMW) were isolated from the flower buds of Syzygium aromaticum (L.) MERR. & PERRY (clove) by anion-exchange chromatography, hydrophobic interaction column chromatography and size exclusion chromatography (LMW: EC-2B-IIIa-2, M.W. ca. 34000; HMW: EC-2C-Ia-2, M.W. ca. 103000). The LMW polysaccharide was mainly composed of Rha, Gal, GalA and Ara (molar %: 24.1, 18.9, 18.0 and 17.9, respectively) with 10.8% of sulfate and 18.2% of protein. The HMW fraction consisted of Ara, Gal, Glc and Rha (molar %: 26.0, 23.7, 17.5 and 12.4, respectively) with 15.4% of sulfate and 8.0% of protein. Both polysaccharides had the backbone of type I rhamnogalacturonan and the side chain of arabinan. Also, most of the sulfates were attached at the position 6 of 3-linked galactosyl residues. Compared to the antithrombotic activity of the HMW fraction (plasma clotting time of 145 s in APTT assay), the LMW fraction displayed a slightly low activity (90 s). However, animal studies indicated that crude LMW polysaccharide did not show acute toxicity, while the acute LD50 of the HMW fraction was approximately 2-fold lower than that of heparin.

Dynamic electrorheological effects and interparticle force between a pair of rotating spheres

We consider a two-particle system in which a particle is held fixed, and the other one rotates around the axis perpendicular to the line joining the particles' centers. The rotating particle leads to a displacement of its polarization charge on the surface. Our results show that the rotational motion of the particles generally reduces the force between the particles. The dependence of interparticle force on the angular velocity of rotation will be discussed.

Isolation of Aeromonas hydrophila in children with diarrhea

Aeromonas species are gram-negative bacilli that lead to a wide spectrum of infectious diseases in human. In the present study, these bacilli were reviewed to assess their significance as enteric pathogens in this area. During the years of 1994 to 1998, the clinical microbiology laboratory received 2150 stool specimens of children with diarrhea. Medical charts of patients who had positive culture for Aeromonas hydrophila were reviewed. A. hydrophila were isolated from 50 (2.3%) of 2150 children with diarrhea. Most patients were outpatients with ages ranging from 5 months to 16 years old (mean age 3.5 years). The male to female ratio was 0.85:1. All patients suffered from watery or loose diarrhea, some with blood-tinged stool. Whether or not they received medication, all patients had uneventful recoveries. The results of antibiotic susceptibility testing revealed that all strains were not susceptible to ampicillin. In summary, A. hydrophila may be considered as a causative agent of gastrointestinal illness in children.

Force between two spherical inclusions in a nonlinear host medium

In an attempt to investigate the effect of nonlinear characteristics on particle interactions, a self-consistent mean-field theory in combination with a multiple image method has been employed to compute the interparticle force. Taking the nonlinearity of the host medium into account, the interparticle force exhibits a nonmonotonic behavior as the applied electric field is increased. We show that the interparticle force increases initially at low fields, goes through a maximum at an optimal electric field, then decreases with increasing field, and vanishes at a critical electric field at which the effective dielectric contrast between the host and the inclusions becomes zero. The influence of a larger volume fraction of inclusions on the interparticle force is also investigated.

Antimicrobial resistance of Streptococcus pneumoniae isolated in Taiwan: an island-wide surveillance study between 1996 and 1997

Between August 1996 and July 1997, 550 clinically significant Streptococcus pneumoniae isolates were collected from 14 geographically separate laboratories in Taiwan. These isolates were serotyped and MICs were determined by agar dilution. Among serotypes covered by the 23-valent vaccine, types 19F, 19A, 23F, 23A and 6B dominated, comprising 255 isolates; among non-vaccine serotypes, types 35, 39, 34, 13 and 31 dominated, comprising 118 isolates. Of the 550 isolates, 310 (56.4%) were resistant to penicillin G (MIC 0. 12 mg/L), 238 (43.3%) with intermediate resistance (MIC 0.12-1 mg/L) and 72 (13.1%) with high-level resistance (MIC 2 mg/L). Most non-susceptible pneumococci were of serotypes 19F and 23F; non-susceptible isolates of these serotypes were distributed across all of Taiwan. Fourteen other antibiotics were tested; 83% of the isolates were resistant to tetracycline, 78% to azithromycin, 74% to erythromycin, 54% to clindamycin and 23% to chloramphenicol. Thus, macrolides can no longer be used as first line agents to treat pneumococcal infections in Taiwan. Multi-resistance (isolates resistant to three or more chemically unrelated antibiotics) was found in each serotype or group, but mostly in types 19F and 23F. The emergence of such strains complicates antibiotic selection, but both types are covered by the 23-valent vaccine, as were 82% of the isolates from blood and eight of the nine from cerebrospinal fluid. Good antibiotic control and appropriate use of this vaccine may improve the current problem in Taiwan, especially for the elderly.

Mature teratoma with secondary infection: case report

Mature teratoma (dermoid cyst) is a common disorder in women of reproductive age. Sometimes the tumor is complicated by torsion, rupture, and malignant change. However, it rarely presents with fever. We present a 38-year-old woman with an intermittent fever for 30 days, who received occasional medical treatment without improvement. She was to our clinic for evaluation and treatment; however, fever persisted for three days without clinical improvement. No definite infection source could be identified except the presence of a huge pelvic tumor. The patient underwent exploratory laparotomy and an ovarian dermoid cyst with infection was noted. Pathology review revealed mature teratoma with superimposed infection by Escherichia coli. Fever impressively subsided on the fifth postoperative day. Although the majority of patients suffering from fever initially search for medical treatment at primary clinics, rare conditions such as persistent fever should be consulted by specialists to make differential diagnosis. Mature teratoma is rarely superimposed by infection and rarely causes fever. Furthermore, the possibility of fever caused by tubo-ovarian abscess (TOA) is often missed in patients with history of tubal ligation since there is a lower incidence of TOA in these unique patients. However, based on this case report, we should be alert whenever long-term fever is noted. Prompt surgical treatment for extirpation and an appropriate antibiotic treatment would be the choice of treatment in such cases.

Intestinal immune system modulating polysaccharides from rhizomes of Atractylodes lancea

Hot water extract (ALR-0) of rhizomes of Atractylodes lanceo DC. was fractionated into MeOH-soluble fraction (ALR-1), supernatant fraction of EtOH precipitation (ALR-3 + 4), and crude polysaccharide fraction (ALR-5). Among these fractions, only ALR-5 showed potent stimulating activity for proliferation of bone marrow cells mediated by Peyer's patch cells. ALR-5 gave three potently active carbohydrate-rich fractions (ALR-5IIa, 5IIb, and 5IIc) by anion-exchange chromatography on DEAE-Sepharose CL-6B, and three active polysaccharides (ALR-5IIa-1-1, ALR-5IIb-2-2, and ALR-5IIc-3-1) were further purified from the respective fractions. The order of activity was revealed to be ALR-5IIb-2-2 > or = ALR-5IIa-1-1 > ALR-5IIc-3-1, ALR-5IIa-1-1, 5IIb-2-2, and 5IIc-3-1 each was eluted as a single peak on HPLC and their molecular weights were estimated to be 74,000, 3,100, 16,000, respectively. ALR-5IIa-1-1 consisted mainly of Ara and Gal (molar ratio; 0.6: 1.0) in addition to a trace amount of uronic acid whereas ALR-5IIb-2-2 and ALR-5IIc-3-1 mainly comprised Ara, Gal, GlcA, and GalA (molar ratio; 0.2: 1.0: 0.2: 0.8, and 0.5: 1.0: 0.7: 1.5, respectively). Methylation analysis indicated that ALR-5IIa-1-1 consisted mainly of terminal Araf, 4- or 5-linked Ara, 3.4- or 3.5-branched Ara, and 3-linked, 4-linked, and 3,6-branched Gal. ALR-5IIb-2-2 and ALR-5IIc-3-1 were composed mainly of terminal Araf, 4- or 5-linked Ara, 4-linked Gal, 4-linked GalA, and terminal GlcA. In addition, ALR-5IIb-2-2 mainly comprised 4-linked Xyl whereas ALR-5IIc-3-1 consisted mainly of 2,4-branched Rha. Single radial gel diffusion indicated that ALR-5IIa-1-1 showed a strong reactivity with beta-glucosyl-Yariv antigen, whereas ALR-5IIb-2-2 and ALR-5IIc-3-1 did not show the reactivity with the antigen. Treatments of ALR-5IIa with NalO4, NaClO2 and pronase did not reduce the stimulating activity for Peyer's patch cells, however combination of exo-alpha-L-arabinofuranosidase and exo-beta-D-(1-->3)-galactanase digestions of ALR-5IIa-1-1 significantly decreased its activity.