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Biomedical subjects

N Itakura

Publications and source records attributed to N Itakura.

At least 19 recordsLinked to original sources
PubMed1999

[Screening test for hematopoietic stem cells in umbilical cord blood with the SE-9000 automated hematology analyzer].

The immature information IMI channel on an SE-9000 automated hematology analyzer was used for detection of stem cells in cord blood and the results were compared with other standard methods, including flow cytometry analysis and progenitor assays. After the removal of red blood cells, the IMI count in cord blood samples significantly correlated with the number of CD34+ cells (r = 0.810), CFU-GM (r = 0.606) and BFU-E (r = 0.961). The cell count in hematopoietic progenitor cell (HPC) area also showed a correlation with CD34+ cell number (r = 0.722), but to a lesser extent than the IMI count; no significant correlations were observed with the numbers of progenitor cells. Cord blood contained higher fractions of CD34+/CD38- and CD34+/CD117+ cells representative of immature subclasses of progenitor cells. This might explain the difference in the HPC module results for the cord blood and peripheral blood stem cell samples. A higher coefficient of correlation was obtained with leukocyte suspensions than with whole blood samples. These results demonstrated the usefulness of IMI-positive cell measurement as a stem cell screening test for cord blood banking.

Antigens, CD34↗
PubMed1996

Discrimination of forearm's motions by surface EMG signals using neural network.

We tried to discriminate different forearm's motions by surface EMG signals using neural network. In order to get a higher discrimination rate, the positions of electrodes were improved. We also tried to discriminate similar motions in order to clarify the limitation of the discrimination by surface EMG signals. Two experiments were carried out. One was to discriminate five different motions: grasp, wrist flexion, wrist extension, forearm pronation, and forearm supination (Experiment 1). The other was to discriminate four similar motions which have different quantitative definitions at grasp, wrist flexion/ extension, or forearm pronation/supination (Experiment 2). Four surface electrodes were placed on the skin above the main active muscles: short radial extensor m. of wrist, supinator m., long radial extensor m. of wrist, and ulnar flexor m. of wrist, considering anatomical functions of the forearm's muscles. EMG signals were recorded during 2 sec while the subjects kept the motions. Recorded EMG signals were sampled at 200 msec intervals after full-wave rectifying and low-pass filtering. Therefore, the number of sampling data patterns of EMG signals was 10 for every motion. Three layers of neural network was used for discrimination. The number of units in the input layer is 4, and the number of units in the output layer is 5 or 4. In order to get the best discrimination rate of the motions, we changed the number of units in the hidden layer from 3 to 12. The neural network was trained by the back-propagation algorithm. In Experiment 1, the best average values of discrimination rates under three patterns of EMG signals for each subject were 96.0%, 98.0%, and 87.2% when the numbers of units in the hidden layer were 10, 11, and 3 respectively. In Experiment 2 using original EMG patterns, the best average values of discrimination rates at grasp, extension/flexion, and pronation/supination were 59.5%, 76.0%, and 25.0% respectively. By using normalized EMG patterns, these were 40.0%, 84.8%, and 55.5% respectively.

Adult↗
PubMed1994

The influence of drinking on physiological tremor and reaction time.

Tremor is an invisible mechanical vibration observed on parts of the body. It is classified into physiological and pathological tremors. It was reported that an oral dose of alcohol could decrease the amplitude of pathological tremor. Usually, drunken level is estimated by the alcohol concentration in expiration. But, physiological tremor can be used to estimate drunken level easily. In this paper, power spectrum of the physiological tremor of index finger and some reaction time of the pedal operations of imitated car driving were measured every 15 minutes for 3 hours under drinking and non-drinking conditions. Subjects were 10 males aged 20 to 25 years. Under drinking condition, the total power values of tremor from 15 to 180 minutes after drinking were smaller than that of before drinking. It is clear that the influence of drinking could be estimated by the total power of the physiological tremor, even when the significant difference of the influence of drinking on reaction time was not found.

Adult↗
PubMed1992

Characteristics of physiological tremor in five fingers and evaluations of fatigue of fingers in typing.

Physiological tremor, which is the invisible mechanical vibration of body part, was measured for five fingers. It was obtained that the power spectrum always has two peaks at 10 and 25Hz for each of the five fingers. The peaks were considered to be generated in the following two loop systems: The component of the lower frequency originated from the central nervous system as a long loop, and that of the higher frequency originated from the muscle-spine loop system as a short loop. The total power, which was the sum of power spectra ranging from 1.5 to 50Hz, was defined as an evaluation index, and it showed characteristic results for the five fingers. The muscular load produced by two hours of typing work was responsible mainly for the increase of total power and for the change of peak frequencies. The mechanism for the change of the power spectrum due to muscular load was well explained by the two-loop theory. It was found that the fatigue of the fingers due to muscular load could be evaluated by the total power.

Adult↗
PubMed1992

On the visual recognition of moving letter.

The visual recognition (i.e., legibility) of moving object was studied. The numerical letters were mainly used as the objects. The influences of (1) direction of the movement, (2) thickness of line of letter (i.e., stroke width), and (3) design of letter to the visual recognition were measured. From these measurements, the optimal numerical letters were proposed in the first step of the study, which were called as IMAL(initial most optimal arabic letters). The visual recognition of both moving letters IMAL and letters JIS (Japan industrial standard) employed for motionless-state was compared for both the moving and the motionless states. In the presentation for motionless state, letters JIS showed lower error rate, but the statistical significance was not proved, while in the presentation for horizontally moving state letters IMAL showed better visual recognition than letters JIS was the significant level of 5%. Therefore, the useful numerical letters for moving state could be designed in the study. Moreover, the visual recognition of letters IMAL was evaluated for various moving velocities. The optimal moving velocities for both letters IMAL and JIS were found.

Computer-Aided Design↗
PubMed1990

Severity of viremia and clinical findings in children with varicella.

The number of varicella zoster virus-infected mononuclear cells in blood samples obtained during 3 days before appearance of vesicular skin rashes could be estimated in 13 of 21 immunocompetent children with varicella and viremia (range, 1-83 per 10(7) mononuclear cells). The virus was isolated from 5% of adherent cells (1/21), 71% of nonadherent cells (12/17), 43% of T lymphocytes (9/21), and 33% of B lymphocytes (7/21). The number of vesicles on the body correlated with the maximum body temperature, duration of fever, and number of infected cells in the blood. These results indicate that varicella zoster virus infection in immunocompetent children is disseminated by circulating T and B lymphocytes and the severity of the viremia is reflected in the severity of the disease.

B-Lymphocytes↗
PubMed1988

Placental transfer of IgG subclass-specific antibodies to varicella-zoster virus.

Commercially available mouse monoclonal antibodies to human IgG subclasses (IgG 1 to IgG 4) were used in an enzyme-linked immunosorbent assay to examine the placental transfer of IgG subclass-specific antibodies to varicella-zoster virus (VZV). All 46 mothers had total IgG antibody to VZV, and an equal level of antibody was found in the cord blood. All of the mothers had high antibody activities to VZV in IgG 1 and IgG 4 subclasses. The majority of the mothers were negative for IgG 2 and IgG 3 VZV antibodies, and the level of antibody found to be positive was very low. The IgG 1 antibody activity in the cord blood was almost equal to that of the maternal, and significantly higher level of IgG 4 antibody was found in the cord than maternal blood.

Adult↗
PubMed1987

Immunoglobulin subclass antibodies to varicella-zoster virus.

Commercially available mouse monoclonal antibodies to human IgG subclass (IgG1 to IgG4) were applied to an enzyme-linked immunosorbent assay to measure IgG subclass-specific antibodies to varicella-zoster virus in children naturally infected with varicella-zoster virus and in varicella vaccine recipients. In children naturally infected with varicella-zoster virus, IgG 1 antibody was detected 2 weeks after onset of the disease in all cases, its activity increased at 1 month after onset, and almost equal antibody value was maintained 10 years after infection. This pattern of antibody response was similar to that of total IgG antibody to varicella-zoster virus after natural infection. On the other hand, low antibody activity was found in IgG2 only at 1 month of the disease. The highest antibody level of IgG3 was shown 2 weeks after onset of the disease; then, it gradually decreased, and no antibody activity was detected 10 years later. IgG4 antibody was first detected 1 month after onset and an almost equal level of antibody was shown 10 years after the disease. After inoculation of children with a live varicella vaccine, in contrast, IgG subclass antibody responses to vaccine recipients were almost equal to those after natural infection.

Antibodies, Viral↗
PubMed1985

Viral replication and immunologic responses in children naturally infected with varicella-zoster virus and in varicella vaccine recipients.

Replication of varicella-zoster virus (VZV) and immunologic responses to VZV were examined by a sensitive culture technique for viral isolation and standard immunologic assays in children after close exposure to wild-type VZV or after inoculation with strain Oka varicella vaccine. Naturally infected children who developed clinical varicella had viremia between five days before and one day after clinical onset of disease, with the highest isolation rate one and two days before onset, and seroconversion followed two days later. Virus was not isolated from blood 12 and 13 days after contact in subclinically infected children. In the vaccine recipients a positive skin test reaction to VZV was observed as early as four to five days after immunization, and antibody appeared later. Virus was not isolated from blood and throat of the vaccinees from three to 14 days after immunization.

Antibodies, Viral↗
PubMed1982

Breath-by-breath VCO2 and VO2 required compensation for transport delay and dynamic response.

Both transport delay (DELAY) and dynamic response (RESPONSE) of a mass spectrometer would theoretically result in considerable errors in the breath-by-breath calculation of VCO2 and VO2. However, curiously, the contribution of RESPONSE has been ignored. The purpose of this study is to quantify the error caused by RESPONSE. We found that RESPONSE of a mass spectrometer was regarded as a first-order response. We determined DELAY and time constant (T) of RESPONSE and compensated the on-line calculation for both DELAY and RESPONSE and for DELAY only. With T of 150 and 100 ms, deviations of VCO2 from the gas-collection method were 8 +/- 6 and 8 +/- 6 ml/min with compensation for both DELAY and RESPONSE, and 69 +/- 10 and 50 +/- 5 ml/min with compensation for DELAY only, respectively (mean +/- SD). Similar results were obtained with VO2. A computer simulation of error caused by RESPONSE disclosed that the error linearly increased with increasing T. We conclude that to be accurate within +/- 5% of the exact value, compensation should be made when T exceeds 25 ms.

Biological Transport↗
PubMed1979

Relationship between alveolar PO2 and the rate of p-nitroanisole O-demethylation by the cytochrome P-450 pathway in isolated rabbit lungs.

The relationship between alveolar PO2 and the rate of O-demethylation of p-nitroanisole, a model substrate for cytochrome P-450 -linked mixed-function oxidation, was evaluated in the isolated rabbit lung perfused with Krebs-Ringer bicarbonate buffer. The appearance of the product, p-nitrophenol, in the pulmonary perfusate was measured spectrophotometrically, The PO2 of the ventilating gas was varied with an accurate gas mixing pump and measured with an electrochemical O2 analyzer. In control lungs ventilated with 5% CO2 in air, the rate of p-nitrophenol production was approximately equal to 3.1 +/- 0.04 (mean +/- SE; n = 9) mumol/h per g dry wt. p-Nitrophenol production was unaltered when O2 in the ventilating gas was decreased to 1%, but it was depressed reversibly when alveolar O2 WAS 0.1% OR LESS AND WAS ABOLISHED DURING VENTILATION WITH 0.005% O2. The rate of the reaction was inhibited by 50% when alveolar PO2 was 0.3 mm Hg representing and intracellular [O2] OF approximately equal to muM. In the presence of metyrapone (0.1--1 mM), an inhibitor of cytochrome P-450-dependent reactions, p-nitrophenol production was 0.07--0.17 mumol/h per g dry wt. Ventilation of lungs with varying CO concentration in 20% O2 resulted in 50% inhibition of p-nitrophenol production when CO concentration was 10% (CO/O2 = 0.5). These results indicated that O-demethylation of p-nitroanisole by the lung is a cytochrome P-450-dependent reaction and that its rate is not affected until alveolar PO2 is less than 1 mm Hg.

Animals↗
PubMed1977

Cytochrome P450-linked p-nitroanisole O-demethylation in the perfused lung.

Oxidative demethylation of p-nitroanisole, a cytochrome P450-linked mixed-function oxidation, was evaluated in isolated perfused rat and rabbit lungs. The product, p-nitrophenol, was monitored continuously in the lung effluent by spectrophotometric measurement. Pulmonary p-nitrophenol production in mumol/h per g dry wt was 6.2+/-0.4 by rabbits and 2.0+/-0.3 by rats (mean+/-SE). Maximal activity of the reaction required pulmonary perfusion rates in excess of 60-80 ml/min per g of dry lung. The half-maximal rate of p-nitrophenol production was observed with p-nitroanisole concentration of 13 micron. Pretreatment of rabbits with chlorpromazine increased p-nitroanisole O-demethylation activity by 63% but phenobarbital pretreatment had no effect. Ventilation with 75% carbon monoxide plus 20% O2 reversibly inhibited the reaction. Specific activity of p-nitroanisole demethylase in the microsomal fraction was 0.5 nmol/min per mg protein in rabbit lungs and 0.1 nmol/min per mg protein in rat lungs. Other rabbit lung subcellular fractions compared with microsomes had significantly lower specific activity. This study demonstrates that p-nitroanisole O-demethylation can be continuously monitored in the intact lung and describes conditions necessary for maximal activity of this pathway.

Animals↗