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Tohru Saitoh

Publications and source records attributed to Tohru Saitoh.

11 recordsLinked to original sources
PubMed2006

The development of a multichannel electrode array for retinal prostheses.

The development of a multielectrode array is the key issue for retinal prostheses. We developed a 10 x 10 platinum electrode array that consists of an 8-microm polyimide layer sandwiched between 5-microm polymonochloro-para-xylylene (parylene-C) layers. Each electrode was formed as a 30-microm-high bump by Pt/Au double-layer electroplating. We estimated the charge delivery capability (CDC) of the electrode by measuring the CDCs of two-channel electrode arrays. The dimensions of each electrode of the two-channel array were the same as those of each electrode formed on the 10 x 10 array. The results suggest that for cathodic-first (CF) pulses, 80% of electrodes surpassed our development target of 318 microC/cm2, which corresponds to the charge density of pulses of 500 micros duration and 200 microA amplitude for a 200-microm-diameter planar electrode.

Electrodes, Implanted↗
PubMed2006

Polymer-mediated extraction of the fluorescent compounds derived by Hantzsch reaction with dimedone for the sensitive determination of aliphatic aldehydes in air.

An extraction method based on the thermo-responsive precipitation of a water-soluble polymer, poly(N-isopropylacrylamide) [PNIPAAm], was applied to the concentration of dimedone (5,5-dimethylcycrohexane-1,3-dion) derivatives for the highly sensitive determination of aldehydes in air. Aliphatic aldehydes including formaldehyde, acetaldehyde, propanal, 1-butanal, 1-heptanal, and 1-hexanal in air were well solubilized into the aqueous solution of dimedone and ammonium acetate by mixing the solution and air sample in a polyvinyl fluoride bag. Fluorescent derivatives of aldehydes that had formed by the Hantzsch reaction with dimedone were concentrated by polymer-mediated extraction. The recoveries of the fluorescent compounds increased with increasing the carbon number of aldehyde and were more than 80% for the derivatives from aldehydes having more than three carbon atoms under the optimal conditions. Microgram per m3 (sub-ppb) levels of the aliphatic aldehydes, propanal, 1-butanal, 1-heptanal, and 1-hexanal, in ambient air were successfully determined by HPLC separation with fluorometric detection. The sampling volume and time required were only 1l and 20 s, respectively.

Acetates↗
PubMed2005

Solid phase extraction of some precious metals from hydrochloric acid to polystyrene-divinylbenzene porous resin impregnated with polyoxyethylene-type nonionic surfactant.

The solid phase extraction of gold(III), platinum(II), and palladium(II) to surfactant-impregnated polystyrene-divinylbenzene porous resin (XAD-4) was studied. The extracting media could be prepared just by mixing the resin in aqueous surfactant solutions. XAD-4 impregnated with a nonionic surfactant, polyethylene glycol monooleyl ether, was useful for extracting gold(III) from hydrochloric acid. The extractions of platinum(II) and palladium(II) were improved in the use of XAD-4 impregnated with a nitrogen-containing nonionic surfactant, polyethylene glycol stearyl amine. On the other hand, base metals such as copper(II), cobalt(II), nickel(II) and zinc(II), were hardly extracted.

Chemistry Techniques, Analytical↗
PubMed2005

Concentration of polyaromatic hydrocarbons in water to sodium dodecyl sulfate-gamma-alumina admicelle.

Polyaromatic hydrocarbons (PAHs) in water were concentrated into sodium dodecyl sulfate (SDS)-gamma-alumina and di-2-ethylhexyl sodium sulfosuccinate (Aerosol-OT, AOT)-gamma-alumina admicelles. The comparison of the binding constants (Kad[={adsorbed concentration of the solute (mol/g surfactant)}/{the concentration in the bulk aqueous phase (mol/ml)}] indicated almost the same extraction abilities of the both admicelles. However, better and more reproducible recovery was obtained in the concentration of PAHs into the SDS-gamma-alumina admicelle. PAHs in tobacco smoke that were trapped in water were successfully concentrated into SDS-gamma-alumina admicelle for the HPLC analysis.

Aluminum Oxide↗
PubMed2004

Protein separation with surfactant-coated octadecylsilyl silica involving Cibacron blue 3GA-conjugated nonionic surfactant.

A novel medium for protein separation, namely affinity admicelle, was prepared by mixing of octadecylsilyl (ODS) silica gels, a polyoxyethylene-type nonionic surfactant (Triton X-100), and a surfactant-conjugated substrate (affinity ligand) in an aqueous solution. The ligand was synthesized by mixing a triazine dye (Cibacron Blue 3GA, CB) and a polyethylene glycol monooleyl ether (C18EO7, C18EO10, or C18EO20) having different length of polyoxyethylene moiety in weakly alkaline solutions. The amount of Triton X-100 sorbed on 1 g of ODS silica was 0.2 mmol. Affinity ligands having highly hydrophobic oleyl group were predominantly sorbed on ODS silica. The losses of Triton X-100 and affinity ligand were within 0.3% and negligible by washing the admicelles were with a 25-fold volume of 1 mM Tris-HCl solution (pH 7.4). The coating ODS silica with Triton X-100 was effective to prevent the irreversible sorption of albumin (bovine, serum). An NADH-dependent enzyme, alcohol dehydrogenase (ADH, yeast), was successfully collected on the admicelles involving CB-conjugated ligands (CB-C18EO20). The maximum collection of ADH to 90 mg/ml of affinity admicelles was 68+/-4%. However, CB-C18EO7 and CB-C18EO10 having shorter polyoxyethylene unit were not available, suggesting the requirement of the spacer moiety in the affinity ligand. The recovery and purification factor based on the ratio of activity (unit)/protein (mg) from Whatman DE52-treated yeast extract was 27% and 12, respectively.

Affinity Labels↗
PubMed2004

Aerosol-OT-gamma-alumina admicelles for the concentration of hydrophobic organic compounds in water.

A novel admicelle composing of a dialkylated anionic surfactant, di-2-ethylhexyl sodium sulfosuccinate (Aerosol-OT, AOT) and gamma-alumina was prepared by mixing them in acidic aqueous solution. The amount of the maximum sorption of AOT on 1 g of alumina at pH 2 was ca. 130 mg. By comparing the fluorescence spectra of N-phenyl-1-naphthylamine in different solvents, the solvent property of AOT-gamma-alumina admicelles was corresponding to that of toluene or diethyl ether. Thus, the AOT-gamma-alumina admicelles had greater hydrophobicity than SDS-gamma-alumina admicelles having similar hydrophobicity to 1-octanol or ethyl acetate. Hydrophobic organic compounds, chlorophenols having more than three chloro substituents, octylphenol, nonylphenol, dibutyl phthalate was almost quantitatively (98% or more) collected onto AOT admicelles composing of 1.5 g gamma-alumina and 150 mg AOT. The greater collection yields rather than those in SDS-admicellar system were ascribable to greater hydrophobicity and stability of AOT admicelles. After the 500-fold concentration, traces (nM) of organic contaminants in water samples were successfully detected with an HPLC having a photometric detector.

Aluminum↗
PubMed2004

Protein separation with surfactant-coated polystyrene involving Cibacron Blue 3GA-conjugated triton X-100.

Through mixing of porous polystyrene particles (Amberlite XAD-4), non-ionic surfactants, and surfactant-conjugated substrates (affinity ligand) in an aqueous solution led to the formation of a novel medium (affinity admicelle) for protein separation. The ligand (CB-Triton) was synthesized by mixing a triazine dye (Cibacron Blue 3GA (CB)) and a polyoxyethylene-type non-ionic surfactant (Triton X-100) in weakly alkaline solutions. Triton X-100 and CB-Triton were competitively sorbed onto XAD-4. Albumin (bovine serum), alcohol dehydrogenase (yeast), and lysozyme (chicken egg) having specific interaction to CB were collected onto the affinity admicelle. On the other hand, the collection of ovalubmin (chicken egg white), having no binding ability to CB, was negligibly small. Lysozyme in 100 microl of chicken egg white, diluted with 900 microl of 10 mM Tris-HCl (pH 7.4), was successfully collected on 18 mg of CB-Triton admicelles and, then, it was eluted with 1 ml of aqueous solution of 100 mM phosphate (pH 7.4). The recovery based on the activity for the lysis of micrococcus and the concentration factor were 60% and 40 (n = 3), respectively.

Micelles↗
PubMed2004

Diagnostic significance of carbamazepine and trigger zones in trigeminal neuralgia.

OBJECTIVE: To investigate the relationship between the efficacy of carbamazepine (CBZ) and the presence of the trigger zone for diagnosis of trigeminal neuralgia (TN). Study design CBZ was administered to 61 patients with suspected TN. All patients underwent intracranial examination by magnetic resonance imaging or computed tomography. The final diagnosis was established by oral and maxillofacial surgeon and neurosurgeon. RESULTS: Of the 61 patients, 50 were finally diagnosed as having TN and 6 as having atypical facial pain. CBZ was effective for pain relief in 45 of the 50 TN patients (90%), and in 5 of the 11 patients (45%) with other diseases (P <.005). However, CBZ also relieved pain in some patients other than TN. Thirty of the 31 patients (97%) with a distinct trigger zone and 20 of the 30 (67%) without a trigger zone were diagnosed as having TN (P<0.005). CONCLUSION: The efficacy of CBZ is an auxiliary indicator of TN and the presence of a distinct trigger zone is a strong indicator of TN.

Adolescent↗
PubMed2002

Concentration of chlorophenols in water with sodium dodecylsulfate-gamma-alumina admicelles for high-performance liquid chromatographic analysis.

Chlorophenols in water were sorbed onto sodium dodecylsulfate (SDS)-alumina (gamma-form) admicelles. The extent of sorption increased with increasing amount of SDS and decreasing solution pH. Conditions for good recovery were obtained when 100 mg SDS and 1.5 g alumina was used at pH 2. However, the yield decreased with a further increase in the SDS concentration due to the formation of normal SDS micelles. The extent of sorption also increased with increasing hydrophobicity of the chlorophenol, indicating that hydrophobic interactions predominate for the collection of analytes. When a cartridge column filled with admicelles was used, >90% of tetrachlorophenol and pentachlorophenol in 200 ml of water samples were rapidly recovered. The sorbed analytes were eluted with 1 ml acetonitrile. The accuracy and precision of the present method were demonstrated for the HPLC analysis with ultraviolet (290 nm) detection of microg l(-1) levels of tetrachlorophenol and pentachlorophenol in river water samples.

Aluminum Oxide↗