Junji Arisawa

Sustained oscillations of membrane potential in a doph model membrane in a constant applied pressure gradient

Abstract A Millipore-filter-dioleylphosphate system showed oscillations of membrane potential in response to a constant applied pressure gradient when the absorbed quantity of dioleylphosphate was between about 4.9 and 7.6 mg/cm 2 . The oscillation frequency was proportional to the change in pressure within a limited range.

Sustained resistance oscillation of millipore DOPH model membrane with calcium ions

Abstract The Millipore DOPH membrane, which consists of a synthetic lipid analogue — dioleylphosphate (DOPH) — absorbed in a Millipore filter, increased its membrane resistance by a factor of 104 when Ca2+ ions combined with it. The membrane resistance experienced an oscillatory change when a constant direct current and static pressure were simultaneously applied. This stable oscillation continued for several hours during the application of the stimuli. The conditions under which the oscillation appeared were as follows: the current stimulus was kept below 0.1 μA, and the pressure stimulus, from 15 to 35 mmHg, was applied as a step function. It was possible to replace the voltage difference across the membrane caused by the constant current flow by the steady membrane potential which was generated by a KCl concentration gradient. Using this replacement, an oscillatory change of the membrane potential was observed at application of pressure as stimulus only; the oscillation frequency increased from 0.8 to 3.5 Hz in the pressure range 13 to 22 mmHg. The increase in membrane resistance was caused by Ca2+ ions combining with O- of the hydrophilic group in the DOPH molecule. The effect was stronger with Ca2+ ions than with other divalent cations (Sr2+, Ba2+, Mg2+).

Antimicrobial activity of Beta-Thujaplicin (Hinokitiol) on heterotrophic bacteria isolated from Reverse Osmosis water using for the preparation of Hemodialysis fluids

To apply for the safety preparation of hemodialysis fluid, antimicrobial activities of beta-Thujaplicin (Hinokitiol) on heterotrophic bacteria such as Sphingomonas paucimobilis and Brevundimonas vesicularis which were isolated from Reverse Osmosis water using for the preparation of Hemodialysis fluids were examined. Less than 10 μg/ml (=ppm) of beta-Thujaplicin showed remarkable growth inhibition on Heterotrophic bacteria even they were incubated in optimal growth condition employing R2A liquid medium. This antimicrobial effect was more clearly observed when employed bacteria were incubated in RO water. Furthermore, this activity was not affected by heat treatment at 80°C for 10 min. These results suggested that small amount of beta-Thujaplicin cloud play useful supplementary substance in the hot water disinfection for several equipments of hemodialysis therapy.

Structural changes and oscillation of electrical resistance in a millipore doph model membrane

Abstract Calcium ions in KCl solution change the surface structure of a Millipore DOPH model membrane and reduce its hydrophilic area. A stereoscopic microscope equipped with a photomultiplier tube on the eyepiece is able to detect quantitatively the conformational changes as a change in the intensity of the reflected light. The degree of the conformational change depends on the kinds of dissolved salt (KCl, NaCl, LiCl) and the pH of the solution. Higher Ca2+ ion concentrations are needed to obtain reflectance changes in LiCl solution. From these results it was concluded that the conformational changes are caused by replacement of monovalent K+ ions by divalent Ca2+ ions as conterions of the hydrophilic radicals of the DOPH molecules. The resistance of the Millipore DOPH membrane increases when the conformation is changed by Ca2+ ions: this resistance oscillates when current or pressure stimuli are applied. These stimuli create a partial K+ ion concentration gradient in the membrane which dissociates Ca2+ ions from the hydrophilic radicals of the DOPH molecules. This dissociation results in decreased membrane resistance, and also in a drop of the potential difference across the membrane produced by the constant current. As this drop decreases the K+ ion concentration gradient in the membrane. Ca2+ ions recombine with the hydrophilic radicals, and the membrane resistance recovers as well. The repetition of this process causes the oscillation of the membrane resistance.

Influence of the 50 Hz magnetic field on the body color and the amount of urine of goldfish

We have studied the biological effect of the extremely low frequency (ELF) magnetic fields by using goldfish. The body color changes in the goldfish and changes in the amount of urine were examined. As a result, it found that the amount of urine of the goldfish increased when 50 Hz 62 mT magnetic field was exposed continuously for more than 20 hours and at this time flecks in the scale were observed with light microscope. Furthermore, it found that one of causes, which these phenomena appeared, was an induced current.

Utilization of a newly established gene isolation technique with metal coating hollow fiber membrane for viral gene collection

Metal coating hollow fiber membrane (MCHF membrane) was made of gold metal plating on a polypropylene hollow fiber membrane. This membrane showed a trapping ability for microorganisms like as bacteria and it also can pass the high electric current. In this present report, we tried an isolation of viral gene employing MCHF membrane. MCHF membrane was used for a filter of viral suspension and it also used for an electrical wire of electrophoresis after filtration. Suspension of Herpes Simplex virus (HSV) was filtrated through the MCHF membrane and then the membrane was treated with a lyses solution (1% SDS in 10 mM NaOH). After these processes (about 15 min), the MCHF membrane was placed in the electrophoresis bath as a cathode. Viral gene was released from the MCHF membrane by applying electric current like as an electrophoresis, and the viral gene was accumulated using a semi-permeable membrane, which was placed among the electrodes. In this method, we could identify HSV gene that could be amplified by polymerase chain reaction (PCR). From these results, we considered that a newly established gene isolation technique with the MCHF membrane is a rapid and high performance gene collection method for the examination of virus-contaminated specimen such as blood products.

Study on the simple and rapid gene isolation system using the metal coating hollow fiber membrane

Abstract We proposed a simple and rapid gene isolation system from Escherichia coli O157. The metal coating hollow fiber membrane was used in this system. Because the membrane was coated with metal, it could be used both as a filter and as an electrode. E. coli O157 was trapped in the membrane by aspirating human feces sample with the micropump. After that, to isolate the gene from the bacterial body, which was chemically lysed, an electric field was applied to the membrane. The verotoxin type 1 gene of E. coli O157 could be isolated from the human feces sample, including 4×106 CFU/ml of E. coli O157 by above processes. In addition, concentrating the genes with an electric field enabled detection of E. coli O157 from 4×105 CFU/ml of human feces sample. The required time for gene isolation was no more than 15 min. This system consisted of the micropump, DC power supply and the metal coating hollow fiber membrane. From these results, it was suggested that gene isolation using this membrane might be done automatically because it needed few apparatuses and processes.

Characteristics of Ca2+-induced structural changes of millipore-doph artificial membranes. Possibility of Calcium Ion detection

Abstract The surface structure of an artificial membrane composed of a Millipore filter and a synthetic lipid analogue, dioleylphosphate (DOPH), immersed in KCl solution, changes when the concentration of CaCl2 added to the KCl solution on one side of the membrane reaches a critical value. Using a photomultiplier mounted on the eyepiece of a stereoscopic microscope the structure change can be measured quantitatively as a variation of the intensity of the light reflected from the membrane surface. In the presence of calcium ions, the intensity decreased to approximately 50% of the value in the original hydrophilic state of the membrane in KCl solution only. However, the degree of structural change was dependent on adsorption density of DOPH, solution temperature and solution pH. On the other hand, using the light reflectance curves obtained from the structural observations, the concentration of an unknown amount of CaCl2 in a KCl solution can be determined. Since the reflectance curves shift significantly with variation of the density of DOPH adsorbed on the Millipore filter, it is possible to detect a wide range of CaCl2 concentrations, the detection range stretching from 0.1 to 50 mM CaCl2.

Study of the Metal Coated Hollow Fiber Membrane Electrode for the Amperometric Sugar Detection and the Sensitivity.

The metal coated hollow fiber membrane (MCH) has been applied as a working electrode of an electrochemical detector for high performance liquid chromatography (HPLC). In this paper, the improvements of the sensitivity of the copper coated hollow fiber membrane (Cu-MCH) electrode as a sensor for carbohydrates were described. The MCH electrode had the tubular structure. Therefore, there was a problem of decreasing the output signal by dilution of analysis with the dependence on the inside volume. In order to reduce the inside volume, the plug put inside of the MCH and a thinner hollow fiber membrane were used. The plug was effective to make the MCH electrode sensitive resulting the detection limit (S/N=3) of glucose lowered from 1.7 pmol to 0.95 pmol. The hollow fiber membrane in which inside diameter was thinner was also effective. The detection limit dropped from 1.7 pmol to 0.56 pmol, when it was changed to 0.6 mm from 1.0 mm. In addition, it was effective to decrease the noise current when the hollow fiber membrane of 0.6 mm inside diameter was covered with the copper on the gold (Cu/Au-MCH).The detection limit was improved to 0.24 pmol. The simultaneous detection of sorbitol, glucose, fructose, lactose, saccharose, raffinose and maltose was demonstrated with the Cu/Au-MCH in HPLC. The detection limits were 0.39, 0.24, 0.39, 0.38, 0.58, 0.53 and 0.82 pmol, respectively.

Feasibility test to detect near-axis scattered light

Due to the strong scattering in biological bodies such as mammalian tissues, the optical imaging of internal structure has been difficult. To suppress the effect of scattering, we have developed a technique that makes use of near-axis scattered light (NASL). However, little has been known on the behavior of the NASL in a scattering medium. In this study, the feasibility of the detection of the NASL was tested using a time-resolved measurement technique.