Biomedical subjects

I Karube

Publications and source records attributed to I Karube.

At least 37 records · Page 2Linked to original sources

PubMed2000

Effect of incident angle of light on sensitivity and detection limit for layers of antibody with surface plasmon resonance spectroscopy.

The effect of the incident angle of light on sensitivity and the detection limit for surface-plasmon resonance spectroscopy were examined. The sensitivities and the detection limit were experimentally measured using an antibody as a modeled analyte in the incident angles of a light region of 66-76 degrees. The results showed that the sensitivity of a smaller incident angle was higher than that of a larger one. For instance, the sensitivity of a 66 degree incident angle was three times higher than that of a 76 degree incident angle. The detection limit with a 66 degree incident angle was one-tenth of that with a 76 degree incident angle. These sensitivities and detection limits were compared with those of a commercially produced surface-plasmon resonance instrument. This comparison demonstrated that a wavelength resolution of the order of less than 10(-2) nm was necessary to obtain satisfactory sensitivities and detection limits. In addition, the refractive index and thickness of the antibody layer formed on a sensor surface was proposed by experimental results and theoretical calculation.

Adsorption↗

PubMed2000

Optical fiber biosensor for the determination of low biochemical oxygen demand.

An optical fiber biosensor was developed for the evaluation of low Biochemical Oxygen Demand (BOD) values in river waters. Artificial wastewater (AWW) solution was employed as standards for the calibration of the BOD sensor. The response time of the sensor was 15 min, and the optimal BOD response was observed at 30 degrees C, pH 7.0. A linear relationship was obtained between the output voltage and BOD5 values, and the range of determination was 1-10 mg l(-1) BOD. The sensor response was almost not influenced by chloride ion up to 1000 mg l(-1), and also not affected by heavy metal ions (Fe3+, Cu2+, Mn2+, Cr3+, Zn2+). The BOD of river waters was estimated by using the optical fiber biosensor, and good correlation between the sensor and BOD5 test was obtained (r2 = 0.971).

Bacteria↗

PubMed2000

Increasing the sensitivity of piezoelectric odour sensors based on molecularly imprinted polymers.

The molecular imprinting technique has been used to create sensors with a predetermined selectivity for molecules in the gas phase. Based on previous results, piezoelectric quartz crystals were first coated with a layer of nylon, to provide increased sensitivity, and then a layer of a polymer imprinted with 2-methylisoborneol (MIB) was applied to endow the device with selectivity. The response of the 'imprinted' sensor was significantly higher than the response of the 'non-imprinted' sensor at MIB concentrations above 10 ppb. Our new sensor is thus 20 times more sensitive than our previous device. At concentrations greater than 10 ppb, the response of the 'non-imprinted' sensor to geosmin, another odorant often accompanying MIB, was significantly higher than the response of the 'imprinted' sensor. A number of other odorants were examined and, as in our previous work, the responses of the 'non-imprinted' sensors were found to be to greater than the responses of the 'imprinted' sensors.

Camphanes↗

PubMed2000

Bioassay of bile acids using an enzyme-linked DNA aptamer.

A new analytical method for the detection of bile acids has been developed by adopting an alkaline phosphatase-linked DNA oligomer that binds to bile acids. A 5'-biotin-labeled DNA oligomer with a 40-nucleotide length that is defined by the in vitro selection method was connected with alkaline phosphatase through an avidin-biotin linkage and applied to an enzyme immunoassay format. Sample solutions were incubated with small aliquots for a cholic acid-immobilized agarose matrix, on which the alkaline phosphatase-linked DNA oligomer had been bound prior to carrying out the assay. The amount of the alkaline phosphatase-linked DNA oligomer dissociated from the cholic acid-immobilized agarose matrix, which was detected using a fluorogenic substrate for alkaline phosphatase, indicated the amount of bile acids in the samples. The results suggest that the DNA aptamer directly linked with the reporter enzyme is applicable as a detector ligand for the immunoassay format. A linear calibration range was obtained for cholic acid between 0.1 to 5 mmol l-1 with a limit of detection of 10 mumol l-1. The %RSD was 7 at 5 mmol l-1 of cholic acid.

Animals↗

PubMed2000

A mediator-type biosensor as a new approach to biochemical oxygen demand estimation.

A novel biosensor for the determination of biochemical oxygen demand (BOD) was developed using potassium hexacyanoferrate(III) [HCF(III)] as a mediator. The sensor element consists of a three-electrode system, with both working and counter electrodes compactly integrated as a disposable using etching and electroplating processes. Pseudomonas fluorescens biovar V (isolated from a wastewater treatment plant) was immobilized on the surface of the working electrode using poly(vinyl alcohol)-quaternized stilbazol (PVA-SbQ) photopolymer gel. Synthetic wastewater described by the Organization for Economic Cooperation and Development (OECD) was used as a standard solution instead of glucose-glutamic acid synthetic wastewater. The conditions of amperometric measurement were optimized at +600 mV (vs. Ag/AgCl) operating potential, namely 40 mM HCF(III) in a 0.1 M phosphate buffer (pH 7.0) at 20 degrees C. The sensor response was linear from 15 up to 200 mg O l-1 BOD. The response time was 15 min at 200 mg O l-1 BOD. To demonstrate the wide metabolic range of activity of the sensor, the sensor response to 14 substances in four categories of organic compounds was investigated. Further, it was shown that the response of this BOD sensor was not influenced in samples with low concentrations of dissolved oxygen under the measuring conditions used. For real wastewaters, the BOD values were determined using the sensor and compared favorably with those determined by the conventional BOD5 method.

Journal Article↗

PubMed2000

Molecular characterization of cDNA encoding oxygen evolving enhancer protein 1 increased by salt treatment in the mangrove Bruguiera gymnorrhiza.

Young plants of the common Okinawa mangrove species Bruguiera gymnorrhiza were transferred from freshwater to a medium with seawater salt level (500 mM NaCl). Two-dimensional gel electrophoresis revealed in the leaf extract of the plant a 33 kDa protein with pI 5.2, whose quantity increased as a result of NaCl treatment. The N-terminal amino acids sequence of this protein had a significant homology with mature region of oxygen evolving enhancer protein 1 (OEE1) precursor. The cloning of OEE1 precursor cDNA fragment was carried out by means of reverse transcription-PCR (RT-PCR) using degenerated primers. Both 3'- and 5'-regions were isolated by rapid amplification of cDNA ends (RACE) method. The deduced amino acid sequence consisted of 322 amino acids and was 87% identical to that of Nicotiana tabacum. In B. gymnorrhiza, the predicted amino acid sequence of the mature protein starts at the residue number 85 of the open reading frame. The first 84-amino acid residues correspond to a typical transit sequence for the signal directing OEE1 to its appropriate compartment of chloroplast. The expression of OEE1 was analyzed together with other OEE subunits and D1 protein of photosystem II. The transcript levels of all the three OEEs were enhanced by NaCl treatment, but the significant increase of D1 protein was not observed.

Algal Proteins↗

PubMed2000

Detection of PCR products of Escherichia coli O157:H7 in human stool samples using surface plasmon resonance (SPR).

A method for the rapid detection of verotoxin-producing Escherichia coli O157:H7 in stools was evaluated. Strains possessing Shiga toxin-2 (stx-2) genes were isolated from stool samples and amplified using oligonucleotide primers. Stools spiked with cultured E. coli O157:H7 (strain 298 or strain 1646) were detected to be polymerase chain reaction (PCR) positive at 10(2) cfu per 0.1 g of stool. Stool samples from patients and healthy carriers showed a high correlation between positive results for a PCR and the presence of verotoxin-producing E. coli O157:H7, confirmed by isolation of serotype O157:H7 on sorbitol MacConkey medium (10 of 10 stool samples). These PCR products could be detected using a BIAcore 2000 surface plasmon resonance device using peptide nucleic acid as a sensor probe. In this report we use this method for the rapid detection of DNA from significant pathogenic organisms.

Carrier State↗

PubMed1999

Application of peptide nucleic acid to the direct detection of deoxyribonucleic acid amplified by polymerase chain reaction.

Double-stranded DNA amplified by polymerase chain reaction (PCR) was detected by peptide nucleic acid (PNA) using a BIAcore 2000 biosensor based on surface plasmon resonance (SPR). PNA is an artificial oligo amide that is capable of forming highly stable complexes with complementary oligonucleotides. We succeeded in the direct detection of double-stranded DNA, amplified by PCR with high-sequence specificity. It was shown that the target DNA was available for detection over the range of 40-160 nM. Therefore, the detection limit was 7.5 pmol of the target DNA (143 bases, applied volume 30 microliters). Our DNA detection system, the combination of BIAcore and the probe PNA, could detect the target DNA with good reproducibility. In this report, we show that our system is a powerful tool for the diagnosis of pathologically significant DNA.

Bacterial Toxins↗

PubMed1999

Detection of PCR products in solution using surface plasmon resonance.

Polymerase chain reaction (PCR) products were detected using a flow injection-type sensor based on surface plasmon resonance. Asymmetric PCR was used to amplify the target DNA sequence, and two products with different length were produced. The novelty of our DNA detection system was that our target DNA was double stranded but the probe binding site, located in the 3'-terminus, was single stranded. This avoids the formation of intra- and intermolecular complexes. This novel design permitted us not only to detect PCR product but also to develop a rapid detection system for the detection of the verotoxin 2 gene of Escherichia coli O157:H7.

Bacterial Toxins↗

PubMed1999

The development of microfabricated biocatalytic fuel cells.

The production of electricity by biocatalytic fuel cells has been feasible for almost two decades and can produce electric power at a practical level. These fuel cells use immobilized microorganisms or enzymes as catalysts, and glucose as a fuel. A microfabricated enzyme battery has recently been made that is designed to function as a power supply for microsurgery robots or artificial organs.

Animals↗

PubMed1999

Multifunctional biocompatible membrane and its application to fabricate a miniaturized glucose sensor with potential for use in vivo.

A multifunctional membrane with biocompatibility, diffusion-limiting effect, and the ability to curtail the responses of an H(2)O(2) electrode to ascorbate and urate was prepared. It was composed of MB, AB, and CTA, where MB is the copolymer of 2-methacryloyloxyethyl phosphorylcholine (MPC) and n-butylmethacrylate (BMA), AB is the copolymer of acrylamide-2-methylpropane sulfonic acid (AMPS) and BMA, CTA is cellulose triacetate. Investigation of the biocompatibility of this membrane showed that, compared with CTA, relatively few platelets bound to it. The membrane was coated onto the working electrode of a needle-type glucose sensor on which immobilized glucose oxidase membrane has been coated. The sensor did not respond to ascorbate and urate at their concentration normally encountered in blood. Its response was not inhibited by metal ions in blood at usual concentration. The sensor exhibited superior thermostability in addition to a rapid response (<90 seconds in batch operation), good reproducibility (RE<5%), good stability (more than 36 hours continuously in heparinized whole blood), and a wide dynamic range (5-650 mg/dl glucose). The sensor was used to determine glucose in serum. The data obtained from the sensor showed good agreement with that from a clinical autoanalyzer (R=0.973).

Journal Article↗

PubMed1999

Eicosapentaenoic acid release from the red alga Pachymeniopsis lanceolata by enzymatic degradation.

Forty-eight species of seaweeds from Japanese waters were screened for the valuable polyunsaturated fatty acids eicosapentaenoic acid (EPA). The eight species that contained the highest levels of these compounds were analyzed in detail. Of all species tested the red alga Pachymeniopsis lanceolata contained the highest EPA concentration, and it was present as both the free and bound forms. EPA constituted 38.7% of total fatty acids, and polar lipids were the main constituent of the total lipids in P. lanceolata. EPA was obtained from the marine algae P. lanceolata by enzymatic hydrolysis of the total lipids extract using phospholipase A2 (PLA2). The release of EPA reached a plateau after 10 min of enzymatic treatment. These results suggest that P. lanceolata is a useful natural source of EPA and that PLA2 treatment is a convenient method for obtaining EPA from the red alga.

Eicosapentaenoic Acid↗

PubMed1998

Biosensors for environmental monitoring.

Environmental monitoring is of great importance for its protection. Conventional monitoring methods are often slow and complex and require expensive equipment, making them unsuitable for in situ, real-time monitoring of pollutants. Biosensors based on a combination of a biological sensing element and an electronic signal-transducing element are alternative methods to conventional ones. Biosensors have a number of advantages, such as high selectivity, high stability, and short response time. Various kinds of biosensors have been developed and employed for detection of pollutants such as phosphate, cyanide, and herbicides. Some of these have already been exploited as real-time monitoring in situ. In this article, some of the applications of biosensors for environmental control are described.

Biosensing Techniques↗

PubMed1998

Application of a linear alkylbenzene sulfonate biosensor to river water monitoring.

A novel whole cell biosensor was constructed for the detection of anionic surfactants in aquatic environments. The analysis was rapid, convenient and did not require organic reagents. In this report, the application of this sensor to river water samples was investigated when applied to environmental samples; other organic substances present in river water may affect the measurement of linear alkylbenzene sulfonates. In order to deal with this problem, a correction system was developed using whole cells of Trichosporon cutaneum. This system was applied to in situ 24 h continuous monitoring in the Saka river.

Benzenesulfonates↗

PubMed1998

Quantitative analysis of polymerase chain reaction using anisotropy ratio and relative hydrodynamic volume of fluorescence polarization method.

The method based on the combination of polymerase chain reaction (PCR) and fluorescence polarization is presented. A targeted DNA was amplified with a 5'-fluorescein labeled primer, using a 256 bp DNA fragment of stx2 gene in Escherichia coli O157:H7 (188-443 bp) as a template. The fluorescence anisotropy of the 5'-fluorescein labeled primer increased upon the polymerization through Taq polymerase. The conversion of primer to PCR product was quantitatively monitored by anisotropy ratio and relative hydrodynamic volume. This system was also applied to the determination of E.coli O157:H7.

Bacterial Toxins↗

PubMed1998

Investigation of the potential active site of a cyanide dihydratase using site-directed mutagenesis.

Cyanide dihydratase has conserved residues in the amino acid sequence with nitrilase, and cyanide hydratase. The conserved amino acid residues in the cyanide dihydratase from Pseudomonas stutzeri AK61 were altered by site-directed mutagenesis. The enzyme completely lost its activity of the cyanide hydrolysis by the replacement of cysteine-163 to serine. The replacement of tyrosine-53 to phenylalanine caused an increase of the K(m) value of the enzyme for cyanide. Substitution of nine other residues seemed to affect the structure of the enzyme.

Amino Acid Sequence↗

PubMed1998

Application of nitrite reductase from Alcaligenes faecalis S-6 for nitrite measurement.

The enzymatic reaction of nitrite reductase (NIR) from Alcaligenes faecalis S-6 was applied to the measurement of nitrite. NIR was immobilized on the surface of a gold electrode using filter paper and a dialysis membrane, and used as a working electrode in a three-electrode system. Amperometric methods were applied using NIR and the electron mediator 1-methoxy PMS (1-methoxy-5-methylphenazinium methylsulfate). The decrease in cathodic current showed a correlation to nitrite concentration over the range 0-1 mg/l. Measurements using a batch-flow type system gave a lower detection limit of 0.01 mg/l. This is sufficient for the detection of nitrite in natural waters.

Alcaligenes↗

PubMed1998

Cloning and expression of a gene encoding cyanidase from Pseudomonas stutzeri AK61.

The gene coding for cyanidase, which catalyzes the hydrolysis of cyanide to formate and ammonia, was cloned from chromosomal DNA of Pseudomonas stutzeri AK61 into Escherichia coli. The cyanidase gene consisted of an open reading frame of 1004 bp, and it was predicted that cyanidase was composed of 334 amino acids with a calculated molecular mass of 37,518 Da. The amino acid sequence of cyanidase showed a 35.1% and 26.4% homology to aliphatic nitrilase from Rhodococcus rhodochrous K22 and cyanide hydratase from Fusarium lateritium, respectively. A unique cysteine residue of aliphatic nitrilase, which was suggested to play an essential role in the catalytic activity, was conserved in cyanidase. The active form of cyanidase was successfully expressed by a DNA clone containing the cyanidase gene in E. coli. Its productivity was approximately 230 times larger than that of P. stutzeri AK61. The characteristics of the expressed cyanidase, including optimum pH, optimum temperature. Michaelis constant (K(m)) for cyanide and specific activity, were similar to those of the native enzyme from P. stutzeri AK61.

Amino Acid Sequence↗