Immersion angle dependence of the resonant-frequency shift of the quartz crystal microbalance in a liquid: effects of longitudinal wave

We investigated the effects of the longitudinal wave on the immersion angle dependence of the resonant-frequency shift, deltaF, of the quartz crystal microbalance, QCM. In order to study exactly the effects, we employed the three types of cells: normal cell, cell with the glass beads and cell with sponge. The longitudinal wave exists in the normal cell. On the other hand, both the cell with the glass beads and the cell with sponge eliminate the longitudinal wave. As results, we have found that the tendencies of deltaF are the same in the three types of cells. That is, we conclude that the longitudinal wave does not have effects on the immersion angle dependence of deltaF.

Olanzapine potentiates neuronal survival and neural stem cell differentiation: regulation of endoplasmic reticulum stress response proteins

Recent clinical neuroimaging studies have suggested that morphological brain changes occur and progress in the course of schizophrenia. Although the neurogenetic and neurotrophic effects of antipsychotics are considered to contribute to the prevention of reduction in brain volume, the cellular molecular mechanisms of action of antipsychotics have not yet been elucidated. We examined the effects of antipsychotics on the endoplasmic reticulum (ER) stress-induced damages of neurons and neural stem cells (NSCs) using cultured cells. In the neuronal cultures, the atypical antipsychotic olanzapine protected neurons from thapsigargin (1 microM)-induced injury. It was observed that a low concentration of thapsigargin (10 nM) that did not affect the neuronal survival could reduce neuronal differentiation of cultured NSCs, suggesting a role of ER stress in the differentiation function of NSCs. Treatment with olanzapine increased the neuronal differentiation suppressed by the exposure to thapsigargin (10 nM). The thapsigargin-induced ER chaperones, GRP78, which indicate the ER stress condition of the cell, were decreased by the treatment with the atypical antipsychotics olanzapine and quetiapine but not by the typical antipsychotic haloperidol. These results indicate that the amelioration of ER-stress might be involved in the cellular mechanisms of atypical antipsychotics to produce neuroprotective and neurogenetic actions in neurons and NSCs, suggesting potential roles of these drugs for treatment of schizophrenia.

Surface plasmon resonance-based trace detection of small molecules by competitive and signal enhancement immunoreaction

A surface plasmon resonance (SPR)-immunosensor for detection of the low molecular weight compound 2,4-dinitorophenol (DNP) at ultra-low concentration has been developed. The sensor strategy is based on a competitive immunoreaction between DNP and a DNP-protein conjugate, namely DNP-bovine serum albumin conjugate (DNP-BSA). Anti-DNP monoclonal antibody was immobilized on a gold thin-film coated SPR-sensor chip by means of a chemical coupling process. DNP-BSA, on contact with the anti-DNP antibody immobilized SPR-immunosensor chip causes an increase in the resonance angle of the sensor chip. The optimum concentration of immobilized antibody on the SPR-sensor chip is 100 microg mL(-1). The SPR-immunosensor response for free DNP determination using the competitive immunoreaction had a response time of ca. 15 min. Using this method, DNP could be determined in the concentration range 1 ppt to 1 ppb. The SPR signal for ppt levels of DNP was enhanced by a factor of three by subsequently treating immuno-bound DNP-BSA with a secondary anti-DNP antibody.

Antibody immobilization to phospholipid polymer layer on gold substrate of quartz crystal microbalance immunosensor

To modify gold electrode for immunosensor to construct an artificial cell membrane structure, water-soluble amphiphilic phospholipid polymer, poly[2-methacryloyloxyehtyl phosphorylcholine-co-n-butyl methacrylate-co-p-nitrophenyloxycarbonyl poly(ethylene glycol) methacrylate (PMBN)] was applied. The polymer had active ester groups for immobilization of biomolecules and it was converted partially to thiol groups for binding to gold substrates. The partially thiolated PMBN was adsorbed on a gold electrode of quartz crystal microbalance (QCM). Surface characterization of adsorbed PMBN layers was thoroughly investigated with reflectance anisotropy spectroscopy, ellipsometry spectroscopy, dynamic contact angle and X-ray photoelectron spectroscopy measurements. Among several PMBN, having different degree of thiolation, it was concluded that 21.5% thiolated PMBN layer had the most well-ordered phosphorylcholine groups in its outer surface. The proteins adsorption test revealed that the phosphorylcholine group on the outer side of PMBN layers, which was substituted their active ester groups by glycine, showed suppress the non-specific adsorption of proteins, such as bovine serum albumin and gamma-globulin. Also, through antigen-antibody binding evaluation, the anti-C-reactive protein antibody immobilized on the PMBN surface worked well and it was confirmed that denaturation of the antibody on the PMBN layers was hardly occurred in spite of 60 days storage at 4 degrees C. The antibody conjugated phospholipid polymer layer with well-ordered phosphorylcholine group could be outstanding functional membrane for biomedical diagnostic devices without non-specific binding and reduction of immunologic activity of immobilized antibody.

Quartz crystal microbalance immunosensors for environmental monitoring

This paper presents discussion of quartz crystal microbalance (QCM) immunosensors for environmental monitoring. Factors limiting the practical application of antibodies to analytical problems are also presented. Among several candidates for the QCM immunosensor device, selected QCM devices and oscillating circuits were tested thoroughly and developed to obtain highly stable and sensitive frequency signals. The biointerface of QCM immunosensor was designed and controlled to immobilize antibody on the QCM surface, to reduce non-specific binding and to suppress denaturation of immobilizing antibody by self-assembled monolayer technique and artificial phospholipid (2-methacryloyloxyethyl phosphorylcholine (MPC)) polymer. MPC polymer as a antibody-stabilizing reagent was added to reduce non-specific binding of the antigen solution and stabilize the immunologic activity of the antibody-immobilized QCM. In addition, it provides examples for detection and quantitation of environmental samples using QCM immunosensors. The analytical results for fly ash extracted samples of dioxins using the QCM immunosensor indicated a good relationship with GC/MS methods. The integrating protocols of the competitive immunoassay and signal-enhancing step are for detecting low molecular analytes with extremely low detection limits using an QCM immunosensor. Furthermore, its detect limitation was extended from 0.1 to 0.01 ng/ml by the signal-enhancing step when the anti-bisphenol-A antibody conjugated MPC polymeric nanoparticles was used. The QCM immunosensor method has demonstrated its effectiveness as an alternative screening method for environmental monitoring because these results were compared with results obtained through environmental monitoring methods such as ELISA and GC/MS.

Dioxin immunosensor using anti-2,3,7,8-TCDD antibody which was produced with mono 6-(2,3,6,7-tetrachloroxanthene-9-ylidene) hexyl succinate as a hapten

To detect dioxin using a quartz crystal microbalance (QCM) immunosensor, anti-2,3,7,8-tetrachloro-p-dibenzodioxin (TCDD) monoclonal antibodies (MAbs) were produced as types of IgG1 and IgM, with mono 6-(2,3,6,7-tetrachloroxanthene-9-ylidene) hexyl succinate (as a hapten) conjugated with bovine serum albumin (dioxin-BSA). Furthermore, ScFv was generated from hybridoma-producing IgG1 MAb. Among these antibodies, ScFv showed excellent capability for dioxin detection using QCM immunosensors.

Effects of thiopental on bispectral index and heart rate variability

BACKGROUND AND OBJECTIVE

Thiopental has been reported to reduce sympathetic tone, however, it is not clear whether change in heart rate variability is associated with depth of anaesthesia. The purpose of the present study was to evaluate changes in heart rate variability at different depths of hypnosis during induction of anaesthesia with thiopental.

METHODS

We studied 17 ASA I patients scheduled for minor surgery. The depth of hypnosis was monitored by the BIS. Spectral analysis of heart rate variability using a maximum entropy method resulted in a characteristic power spectrum with two main regions, a high frequency and a low frequency. Haemodynamics, entropy, low frequency, high frequency and low frequency/high frequency were monitored in an awake state and after the induction of anaesthesia.

RESULTS

Heart rate increased in a BIS-dependent manner, whereas blood pressure showed no significant changes during the study period. High frequency, entropy and low frequency decreased with a reduction in the BIS value. Low frequency/high frequency showed no significant change during the study period.

CONCLUSIONS

Induction of anaesthesia with thiopental increased heart rate and decreased high frequency, entropy and low frequency in a BIS-dependent manner, indicating that thiopental reduces cardiac parasympathetic tone depending on the depth of hypnosis.

EPCR Ser219Gly: elevated sEPCR, prothrombin F1+2, risk for coronary heart disease, and increased sEPCR shedding in vitro

We have progressively analysed three studies of coronary heart disease (CHD) for a variant in EPCR (Ser219Gly). Initially, in a prospective study, NPHSII, while no overall CHD-risk was identified in heterozygotes, homozygotes for 219Gly exhibited a three-fold elevated risk (HR 3.3, CI 1.22-8.96). In diabetics within NPHSII, there was a suggestion that 219Gly+ was associated with elevated CHD-risk (HR 1.89, CI 0.39-9.06) although numbers were small. To further assess the effect of the variant in diabetes, a case-control study of MI, HIFMECH, was used, in which previous analysis had defined a group with metabolic syndrome, by factor analysis. A significant CHD-risk interaction was identified between genotype and the 'metabolic syndrome' factor (interaction p=0.009). To further assess CHD-risk for this variant in type-2 diabetes and to assess the effect of the variant upon thrombin generation and plasma levels of soluble EPCR, a cross-sectional study of type-2 diabetes was used. A significant CHD-risk was identified for European Whites (OR 2.84, CI 1.38-5.85) and Indian Asians in this study (OR 1.6, CI 1.00-2.57) and the frequency of 219Gly was two-fold higher in Indian Asians. Soluble EPCR levels were strongly associated with genotype, with homozygotes for 219Gly having four-fold higher levels (p<0.0001). In vitro studies of EPCR-transfected cells suggested increased basal release of sEPCR from cells expressing the 219Gly EPCR phenotype. Furthermore, in base-line samples from NPHSII and in the diabetic study, a significant increase in prothrombin F1+2 level was observed for 219Gly. The increased CHD-risk and thrombin generation appears to be acting through increased shedding of the Gly allele from the cell surface.

Characteristics of the series resonant-frequency shift of a quartz crystal microbalance in electrolyte solutions

We report the novel characteristics of the series resonant-frequency shift, DeltaF, of a one-face sealed quartz crystal microbalance (QCM) in solutions of monovalent electrolytes and divalent electrolytes. In the present study, we used NaCl, KCl, LiCl, NaNO3 and CH3COONa as monovalent electrolytes, and MgCl2, CaCl2, MgSO4 and Na2SO4 as divalent electrolytes. These experiments reveal that, in all the solutions, the DeltaF values vary linearly with an increase in the square root of the density-viscosity product of the solutions, and the immersion angle dependence of DeltaF appears. Moreover, we have found that the intercept values of DeltaF are dependent only on the cation species, and that the slope values of DeltaF with the viscosity and density of the solutions are related only to the valence of ions. We also suggest that the DeltaF values are independent of anion species, conductivity and permittivity of the solutions.

Piezoelectric immunosensor for bisphenol A based on signal enhancing step with 2-methacrolyloxyethyl phosphorylcholine polymeric nanoparticle

An immunoassay in which BPA competed with a BPA-horseradish peroxidase conjugate for binding to anti-BPA antibodies, coupled to a piezoelectric (PZ) immunosensor, was able to detect 0.1 ng mL(-1) BPA. To enhance the sensitivity of the assay, we tested nanoparticles approximately 200 nm in diameter, coupled to anti-BPA antibodies, to increase the mass change on the surface of the immunosensor and thereby increase the frequency shift detected. This second step, using nanoparticles coated with anti-BPA antibodies, improved the sensitivity of the assay by approximately eight times at BPA concentrations below 10 ng mL(-1). Field emission-scanning electron microscopy (FE-SEM) showed that polymeric 2-methacrolyloxyethyl phosphorylcholine (MPC) nanoparticles coupled to antibodies remained monodisperse on the surface of the immunosensor and therefore produced stable signals in the immunosensors. Since the frequency shift detected in the assay mainly originated from the mass change on the surface of the PZ crystal, the colloidal stability of the antibody-conjugated particles used in the enhancement step played an extremely important role in achieving a stable and highly sensitive signal.

Dynamical behavior of lipid bilayer membranes for taste substances under random membrane-potential fluctuations

The dynamical behavior of the lipid bilayer membranes was experimentally studied under superposition of random or periodic membrane-potential fluctuations. The analysis of the mutual information has revealed that, in less than 10 Hz of random fluctuations, each of the time series of the mutual information of the transmembrane current for the five chemical substances (taste substances) has its inherent pattern, but not in a periodic fluctuation. On the other hand, the analysis of the power spectrum of the frequency could not distinguish those five basic taste substances in both random and periodic fluctuations. We provide the new detection idea of chemical substances by random fluctuations.

Quartz crystal microbalance immunosensor for highly sensitive 2,3,7,8-tetrachlorodibenzo-p-dioxin detection in fly ash from municipal solid waste incinerators

A quartz crystal microbalance (QCM) immunosensor was developed for the detection of 2,3,7,8-tetrachlorodibenzo-p-dioxins (TCDD) in environmental pollutants. An anti-TCDD antibody was immobilized on the gold surface of the QCM via chemical coupling, and its immunologic activity was then maintained by treatment with an artificial stabilizing reagent such as poly(2-methacryloyloxyethyl phosphorylcholine-co-n-butyl methacrylate). A competitive immunoreaction with TCDD conjugated ovalbumin (TCDD-ovalbumin) was used to detect TCDD. A calibration curve was obtained through the competitive immunoreaction, and linearity was shown from 100 ng mL(-1) to 0.1 ng mL(-1). Also, the cross-reactivities of the anti-TCDD monoclonal antibody were thoroughly evaluated with several TCDD derivatives. The relationships between GC-MS, ELISA, and QCM were compared using fly ash samples from a municipal solid waste, which were prepared using an accelerated solvent extractor. For 23 samples, the experimental relationship between the TCDD concentration by QCM vs. the TCDD concentration by ELISA was y= 1.07x + 2.70, r= 0.99, and the TCDD concentration by QCM vs. the toxic equivalent quantity (TEQ) value by GC-MS was y= 2.46x - 14.98, r= 0.89.