Biomedical subjects

A Miki

Publications and source records attributed to A Miki.

At least 37 records · Page 2Linked to original sources

PubMed2001

Polymorphism of human leukocyte antigen-E gene in the Japanese population with or without recurrent abortion.

PROBLEM: The aim of this study was to investigate the gene frequencies and shared alleles of human leukocyte antigen (HLA)-E gene in Japanese couples with or without recurrent abortion. METHOD OF STUDY: Polymerase chain reaction (PCR)-single strand conformation polymorphism (SSCP) analysis was carried out to detect polymorphism in exon 3 of the HLA-E gene in 30 Japanese couples with recurrent abortion and 38 normal Japanese couples with proven fertility. RESULTS: No point mutation was detected in exon 3 of HLA-E in both recurrent aborters and normal controls. HLA-EG and HLA-ER alleles were detected with frequencies of 66.7% and 33.3% in couples with recurrent abortion and 69.2% and 30.8 in normal couples, respectively. The gene frequency of HLA-EG was higher than that of HLA-ER, which is contrary to that found in Caucasian, African-American and Hispanic people but similar to Chinese people. The frequency of each allele was not significantly different between recurrent aborters and normal controls. The number of shared alleles between each couple with recurrent abortion is not significantly different from that with normal controls. CONCLUSION: Allele frequencies of HLA-E were suggested to be different in Asian people from those in other ethnic people. In light of no specific distribution pattern in recurrent aborters, HLA-E polymorphism does not seem to play a role in the pathogenesis of recurrent abortion.

Abortion, Habitual↗

PubMed2001

Cross-axis adaptation of pursuit initiation in humans.

PURPOSE: The initial acceleration of pursuit in the open-loop period is under adaptive control and undergoes motor learning. The current study was undertaken to examine the hypothesis that the direction of pursuit initiation can also be adaptively modified. METHODS: Four neurologically and ophthalmologically normal subjects participated in the experiment. A modified step-ramp paradigm was used to induce cross-axis adaptation, in which a ramp target changed its direction orthogonally just after the target crossed the center. Four direction changes were tested in separate experiments: left to up, left to down, down to left, and up to left. During a 30-minute adaptation session, the target moved in one of two randomly chosen directions (right to left or up to down) at one of two randomly chosen speeds (15.6 or 22.3 deg/sec), but the target changed orthogonally in only one direction. A linear regression fit to the initial 100-msec segment of the pursuit trace was used to determine the direction of pursuit initiation. RESULTS: In all cases, an adaptive change in pursuit initiation was gradually induced in the direction called for by the training paradigm. Adaptation was usually completed (90 degrees shift) within the 30-minute training session but declined quickly to an approximate 30 degrees -shift after training. The latency and vectorial amplitude of the initial acceleration remained unchanged. The adaptation was specific for the direction but not the velocity of the target. CONCLUSIONS: This study showed that the direction of pursuit initiation is under adaptive control, as has been shown for saccadic eye movements and the vestibulo-ocular reflex.

Adaptation, Ocular↗

PubMed2001

Adaptive changes in dynamic properties of human disparity-induced vergence.

PURPOSE: Vergence eye movements undergo adaptive recalibration in response to a training stimulus in which the initial disparity is changed just after vergence begins (the double-step paradigm). In the present study the changes in the dynamic properties of convergence, speed and acceleration, were examined by using this double-step paradigm, before and after adaptation. METHODS: Four normal subjects participated. Three-dimensional visual stimuli were provided by a head-mounted display with two liquid crystal diode (LCD) panels. To induce adaptation, a double step of disparity was used: an initial step from distances of 2 to 1 m was followed by a second step to distances of 0.7 m ("increasing paradigm") or 1.4 m ("decreasing paradigm") after a constant period of 0.2 seconds. The dynamic properties of vergence were compared before and after 30 minutes of training with these paradigms. RESULTS: Peak velocity of convergence became significantly greater (increasing paradigm) or smaller (decreasing paradigm) after 30 minutes' training. Changes in the dynamic properties of convergence were also obvious in phase-plane (velocity versus position) and main sequence (peak velocity versus amplitude) plots. Further analysis revealed that adaptive increases in vergence velocity were accomplished by an increase in the duration of the acceleration period, whereas adaptive decreases were induced by a decrease in the maximum value of acceleration. CONCLUSIONS: The pattern of change in the dynamic characteristics of vergence after adaptation was similar to that of saccades and the initiation of pursuit eye movements, suggesting common neural mechanisms for adaptive changes in the open-loop control of eye movements.

Adaptation, Ocular↗

PubMed2000

Contralateral monocular dominance in anterior visual cortex confirmed by functional magnetic resonance imaging.

PURPOSE: Although it is known that the damage to anterior striate cortex results in temporal peripheral visual field loss of the contralateral eye in patients with cerebral visual disturbance, the monocularity of anterior striate cortex has not been demonstrated in normal living humans. The aim of this study was to investigate whether this could be shown noninvasively using functional magnetic resonance imaging of the human visual cortex. METHODS: Eleven normal volunteers were studied with functional magnetic resonance imaging during alternating monocular visual stimulation using a 1.5 Tesla scanner. The data were motion corrected and spatially normalized to the standard brain. The monocular activation of the visual cortex was compared with the activation by the other eye. RESULTS: In the individual data analysis, contralateral eye dominance was always observed in the anterior striate cortex. In the group analysis from 11 subjects, the area with contralateral eye dominance was found in the most anterior part of primary visual cortex where the calcarine fissure merged with the parieto-occipital sulcus. CONCLUSIONS: This study shows that the contralateral eye dominance of anterior striate cortex can be detected noninvasively with functional magnetic resonance imaging during monocular visual stimulation. The finding confirms that the anterior striate cortex, where the monocular temporal crescent is represented, is primarily monocular, but the fact that greatest density of retinal ganglion cells and photoreceptors is in the nasal hemiretina must also be taken into account when interpreting these results.

Dominance, Cerebral↗

PubMed2000

Functional MRI in children with congenital structural abnormalities of the occipital cortex.

Functional MRI techniques were used to map the position of visual cortex in an awake and a sedated child with congenital anomalies of the posterior hemispheres. In one subject with cortical heterotopia, an activated cortex was found distinct from the structurally abnormal area detected on conventional MRI. In a sedated patient with holoprosencephaly, activated cortical areas in the posterior-medial portions of the hemispheres were identified. This study demonstrates the utility of functional MRI in such patients, both awake and sedated.

Adolescent↗

PubMed2000

Decrease of suppressor-inducer (CD4+ CD45RA) T lymphocytes and increase of serum immunoglobulin G due to perceived job stress in Japanese nuclear electric power plant workers.

To clarify the effects of perceived job stress on the immune system, a cross-sectional study was conducted in 116 male Japanese workers of a nuclear electric power plant (age, 20 to 39; mean, 31 years). Perceived job stress, i.e., psychological job demand, job control, worksite social support, and job strain, was assessed by means of the Japanese version of the Job Content Questionnaire. The job strain score was calculated as the ratio of the job demand score to the job control score. Blood samples were taken from all workers, and numbers of T and natural killer cell subpopulations, B lymphocytes, total lymphocytes and white blood cells, and serum concentrations of immunoglobulins (IgG, IgM, IgA, IgE and IgD) in their blood were measured. The workers were divided into higher and lower strain groups according to their job strain scores. The number of CD4+ CD45RA+ T lymphocytes in the higher strain group having the job strain score of 0.5 or more (41 workers) was significantly smaller than that in the lower strain group having the score of less than 0.5 (75 workers). In contrast, the serum IgG concentration in the former group was significantly higher than that in the latter group (analysis of covariance with age and smoking as covariates). Also, the numbers of total CD4+ T and total T (CD3+) lymphocytes and of white blood cells in the former group were significantly smaller than those in the latter group. After controlling for age and smoking by the partial correlation coefficient in all 116 workers, the number of CD57+ CD16+ natural killer cells was inversely correlated with job demand and with job strain; the number of CD8+ T lymphocytes was positively correlated with worksite social support; and serum IgG and IgM concentrations were positively correlated with job strain. It is suggested that higher job strain decreases the number of CD4+ CD45RA+ T lymphocytes in male Japanese workers but increases serum IgG concentrations.

Adult↗

PubMed2000

Immunotherapy prevents recurrent abortion without influencing natural killer receptor status.

PROBLEM: We assessed the expression of natural killer (NK) receptors in recurrent aborters before and after immunotherapy using their husbands' peripheral blood mononuclear cells (PBMCs). METHOD OF STUDY: Using stored PBMCs from recurrent aborters before and after the immunotherapy, the expression of NK receptors, CD158a, CD158b, CD159 and CD94, were analyzed using monoclonal antibodies for respective receptors. The diversity of killer activatory receptors (KARs) and killer inhibitory receptors (KIRs) was also examined using reverse transcriptase-polymerase chain reaction (RT-PCR)-single strand conformation polymorphism (SSCP) method. RESULTS: In recurrent aborters, no apparent changes in NK receptor expression and the balance between KARs and KIRs were found before and after the immunotherapy. CONCLUSION: The allo-human leukocyte antigen (HLA)-stimulation caused by the immunotherapy for recurrent aborters did not affect the expression of NK receptors and the ratio of KARs to KIRs regardless of the outcome of subsequent pregnancies, suggesting that recurrent aborters may benefit from the immunotherapy through mechanisms unrelated to alteration in NK receptor status.

Abortion, Habitual↗

PubMed2000

Theoretical basis for herbal medicines, Tokishakuyaku-san and Sairei-to, in the treatment of autoimmunity-related recurrent abortion by correcting T helper-1/T helper-2 balance.

PROBLEM AND METHOD OF STUDY: To get insight into the basis for the empirical usage of herbal medicines in the treatment of recurrent abortion, we examined whether Tokishakuyaku-san (Toki) and Sairei-to (Sai) modulate T helper-1 (Th1) and T helper-2 (Th2) cytokine release from peripheral blood mononuclear cells (PBMCs). The effects of these medicines were investigated as related to human leukocyte antigen (HLA)-G, a non-classical HLA class I antigen expressed on trophoblasts and a putative crucial player involved in fetomaternal immune interplay. RESULTS: Toki and Sai increased the release of Th1 group cytokines, tumor necrosis factor (TNF)-alpha and interferon (IFN)-gamma while preserving the inhibitory effect of HLA-G on the release of these cytokines. As for Th2 group cytokine release, Toki was without effect in modulating interleukin (IL)-4 release, regardless of the presence of HLA-G, whereas Sai nullified the effect of the presence of HLA-G to stimulate the release of IL-4 without affecting its release in the absence of HLA-G. CONCLUSION: Toki and Sai may have therapeutic potential, particularly in autoimmunity-related recurrent abortion where Th2 response is pathologically enhanced, but not in recurrent abortion involving alloimmune fetomaternal derangement, a condition of, rather, an enhanced Thl response.

Abortion, Habitual↗

PubMed2000

Sleep problems in white-collar male workers in an electric equipment manufacturing company in Japan.

In order to clarify poor sleep habits and prevalence in sleep problems (disturbances) of healthy male white-collar workers and the relationship of these to age and job type, a total of 1,161 Japanese employees of an electric equipment manufacturing company (aged 23 to 59, mean 37 years) were surveyed by means of a mailed questionnaire. The workers were asked about eleven sleep habits. They were also divided into four groups according to age and job type: 23-29 (n = 226), 30-39 (n = 597), 40-49 (n = 225) and 50-59 (n = 113); managerial (n = 209), professional (n = 336), technical (n = 475) and clerical (n = 134). In this study, the sleep problems were defined as who had at least one of the following four poor sleep habits: 1) taking more than 30 minutes to fall asleep, 2) awakening during sleep (ADS) almost every day, 3) early morning awakening (EMA) almost every day, and 4) excessive daytime sleepiness (EDS) at work almost every day. Analyses showed that sleep problems were present in 26.0% of workers; the problems were most serious among workers aged 50 years and more (36.0%) which may be due to a significant increase in the prevalence rate of EMA. The results revealed that sleep problems are common in male white-collar daytime workers. The findings also suggest a need for increased attention to sleep problems in older workers and younger ones with EDS at work.

Adult↗

PubMed2000

Reproducibility of visual activation in functional MR imaging and effects of postprocessing.

BACKGROUND AND PURPOSE: Functional MR imaging studies of the brain should be interpreted in the context of their reproducibility. We assessed the reproducibility of visual activation measured by functional MR imaging and analyzed the effect of image transformation to standard space. METHODS: Seven healthy volunteers were studied twice with echo-planner functional MR imaging at 1.5 T during visual stimulation. The studies were separated by an interval of 2 to 7 days. Functional images were analyzed after spatial normalization to the space described by Talairach and Tournoux and/or after coregistration of the images of the second study with the images of the first study. The number of active voxels for each study was determined at three thresholds. In addition, the change in the center of the mass of activation, the mean change in signal intensity, and the mean t value within the activated area were measured. These reproducibility indexes were calculated for the spatially normalized and nonnormalized data for each subject. RESULTS: Variations in visual activation were observed between the two studies in the same individual as well as across subjects. There was no evidence of an effect from image transformation on reproducibility on any of the measures. CONCLUSION: Our findings show that the reproducibility of activation in functional MR imaging may be much more variable across subjects than suggested in previous studies. The use of different types of image transformation (coregistration, spatial normalization) does not significantly affect the reproducibility of visual activation.

Adult↗

PubMed2000

Context-specific adaptation of pursuit initiation in humans.

PURPOSE: To determine if multiple states for the initiation of pursuit, as assessed by acceleration in the "open-loop" period, can be learned and gated by context. METHODS: Four normal subjects were studied. A modified step-ramp paradigm for horizontal pursuit was used to induce adaptation. In an increasing paradigm, target velocity doubled 230 msec after onset; in a decreasing paradigm, it was halved. In the first experiment, vertical eye position (+/-5 degrees ) was used as the context cue, and the training paradigm (increasing or decreasing) changed with vertical eye position. In the second experiment, with vertical position constant, when the target was red, training was decreasing, and when green, increasing. The average eye acceleration in the first 100 msec of tracking was the index of open-loop pursuit performance. RESULTS: With vertical position as the cue, pursuit adaptation differed between up and down gaze. In some cases, the direction of adaptation was in exact accord with the training stimuli. In others, acceleration increased or decreased for both up and down gaze but always in correct relative proportion to the training stimuli. In contrast, multiple adaptive states were not induced with color as the cue. CONCLUSIONS: Multiple values for the relationship between the average eye acceleration during the initiation of pursuit and target velocity could be learned and gated by context. Vertical position was an effective contextual cue but not target color, implying that useful contextual cues must be similar to those occurring naturally, for example, orbital position with eye muscle weakness.

Adaptation, Ocular↗

PubMed2000

Functional magnetic resonance imaging of lateral geniculate nucleus at 1.5 tesla.

Although activation of the lateral geniculate nucleus has been detected by functional magnetic resonance imaging with magnetic field strengths higher than 2.0 Tesla, there have been no reports of functional magnetic resonance imaging of the lateral geniculate nucleus with the more widely available 1.5 Tesla scanner. The authors used functional magnetic resonance imaging techniques at 1.5 Tesla to detect lateral geniculate nucleus activation in five of seven healthy subjects. This study shows that visual activation of the lateral geniculate nucleus can be obtained with functional magnetic resonance imaging using conventional 1.5 Tesla scanners.

Adult↗

PubMed1999

Determination of ethyl glucuronide, a minor metabolite of ethanol, in human serum by liquid chromatography-electrospray ionization mass spectrometry.

A rapid and sensitive determination procedure using liquid chromatography-electrospray ionization mass spectrometry (LC-ESI-MS) has been developed for the determination of ethyl glucuronide (EtG) in human serum. Samples were precipitated with methanol, centrifuged and the supernatant was evaporated to dryness followed by reconstitution with distilled water. As mobile phase 30 mM ammonium acetate-acetonitrile (30:70, v/v) was utilized. The base peak observed at m/z 221 was the [M-H]- ion of EtG, which was detectable in satisfactory sense. The detection limit was 0.03 microg/ml in the selected ion monitoring mode. A calibration graph constructed for EtG in serum gave good linearity over the range from 0.1 to 25 microg/ml. This paper also presents the application of this LC-ESI-MS procedure to the analysis of authentic serum samples.

Alcohol Drinking↗

PubMed1999

Tolerance of NK and LAK activity for HLA class I-deficient targets in a TAP1-deficient patient (bare lymphocyte syndrome type I).

NK cells recognize target cells that lack HLA class I molecules and lyse them, according to the 'missing self' hypothesis. It was previously reported that a TAP2-deficient patient with an HLA class I-deficiency, had a normal number of NK cells but that the lymphocytes of this patient had lost their NK activity against K562 cells. In this study, we investigated the HLA class I-recognizing NK receptor expressions and the NK and LAK activities of the lymphocytes of a TAP1-deficient patient. The patient had a normal number of NK cells. Although the lymphocytes showed LAK activity against class I expressing targets following IL-2, IL-12 and IL-15 stimulation for 3 days, neither NK nor LAK activity against targets lacking class I molecules was induced. The NK cells of the patient expressed class I-recognizing NK receptors, although the percentages of such cells were low. However, no differences were observed in the expression levels of inhibitory and activating NK receptors between lymphocytes of the patient and those of healthy controls, suggesting that the modulation of the NK receptor expression is not primarily responsible for this tolerance. These results also suggest that the lymphocytes of the patient are defective in the recognition of class I-deficient target cells in order to promote the induction of self tolerance.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed1999

The expression of human leukocyte antigen-G on trophoblasts abolishes the growth-suppressing effect of interleukin-2 towards them.

PROBLEM: We have shown the attenuated human leukocyte antigen (HLA)-G expression on trophoblasts and an aberrant expression of interleukin (IL)-2, a cytotoxic cytokine, in decidual tissue in preeclampsia, where deteriorated trophoblastic invasion into decidual layers may constitute a crucial pathogenesis. We hypothesized that the absence of HLA-G might make trophoblasts susceptible to compromise by IL-2. METHOD OF STUDY: We analyzed the growth of HLA-G-negative and positive cell lines, all of which possessed IL-2 receptors, in the culture with or without IL-2 supplementation. RESULTS: The proliferation of HLA-G positive trophoblastic cell lines (BeWo and JEG-3) was not influenced by the addition of IL-2, whereas a HLA-G-negative trophoblastic cell line (JAR) exhibited significantly decreased proliferation when cultured with IL-2. Interestingly, the transfection of JAR cells with HLA-G completely eliminates the growth-inhibitory effect of IL-2. CONCLUSION: The expression of HLA-G may commit trophoblasts to evade cell damage by IL-2, which may be relevant to maternal tolerance of the fetus during pregnancy and its derangement as exemplified by preeclampsia.

Cell Division↗

PubMed1999

Analysis of human leukocyte antigen-G polymorphism including intron 4 in Japanese couples with habitual abortion.

PROBLEM: The purpose of this study was to clarify whether there is a difference between the allele frequency of human leukocyte antigen (HLA)-G in healthy Japanese people and that of Japanese couples with habitual abortion. METHOD OF STUDY: Exons 2, 3, 4, and intron 4 of the HLA-G gene were analyzed in 20 couples with habitual abortion, using polymerase chain reaction (PCR)-single-strand conformation polymorphism (SSCP) analysis. Intron 4 of the HLA-G gene was also analyzed in 54 healthy individuals. The nucleotide sequence of the PCR product of intron 4 was further determined by direct sequencing. RESULTS: Two kinds of nucleotide sequence were identified in intron 4 of the HLA-G gene, one of which was identical to that of HLA-G*01011, and the other was identical to that of HLA-G*01012, G*01013, and G*0104. The frequency of each allele in affected women and their husbands did not significantly differ from that of healthy individuals, and no mutation was found in any affected couple. CONCLUSION: HLA-G allelic abnormality seemed to have little, if any, implication in the pathogenesis of habitual abortion.

Abortion, Habitual↗

PubMed1999

Quantitative assessment of human leukocyte antigen-G protein in amniotic fluid by a double-determinant enzyme-linked immunosorbent assay using anti-human leukocyte antigen-G-specific antibody '87G'.

PROBLEM: The objective of this study was to establish an enzyme-linked immunosorbent assay (ELISA) system, in an attempt to quantify the amount of human leukocyte antigen (HLA)-G protein in amniotic fluid. METHOD OF STUDY: We established a double-determinant ELISA system using the anti-HLA-G specific mouse monoclonal antibody '87G' as a capture antibody and the horseradish-peroxidase labeled rabbit anti-human beta2-microglobulin antibody as a detection antibody. We then measured the concentration of HLA-G protein in amniotic fluid samples from nine normal second-trimester pregnant women and in serum samples from eight normal males. RESULTS AND CONCLUSION: HLA-G protein was detected in amniotic fluid at a concentration of 275 ng/ml (197-343 ng/ml) (median value and 95% confident range), whereas the concentration of HLA-G protein in male serum was below the minimum detection level.

Adult↗

PubMed1999

Effects of sairei-to and tokishakuyaku-san on cytokine release from peripheral blood mononuclear cells upon recognition of HLA-G protein in the treatment of recurrent abortion.

Human leukocyte antigen (HLA)-G has been shown to play a role in establishing pregnancy through the mechanism of modulating cytokine secretion from maternal lymphocytes. To elucidate the mechanisms of actions of the herbal medicines, Sairei-to and Tokishakuyaku-san, in the treatment of recurrent abortion, we investigated whether these medicines modulate cytokine secretion from peripheral blood mononuclear cells (PBMCs) upon recognition of HLA-G protein on trophoblasts. Sairei-to and Tokishakuyaku-san increased the interleukin (IL)-1 beta and tumor necrosis factor (TNF)-alpha secretion and decreased the IL-3 secretion from PBMCs regardless of whether these cells recognized HLA-G protein or not. Accordingly, Sairei-to nullified the effects of HLA-G to reduce the secretion of IL-1 beta and TNF-alpha and to enhance the secretion of IL-3. Tokishakuyaku-san also abolished the effect of HLA-G to reduce IL-1 beta and TNF-alpha secretion but did not affect the increase in IL-3 secretion. Thus, it is conceivable that Sairei-to may normalize Th1/Th2 balance by enhancing Th1 polarization in autoimmunity-related recurrent abortion in which Th1/Th2 balance might be shifted towards Th2 polarization. However, the mechanisms of action of Tokishakuyaku-san when used in treating unexplained recurrent abortion, cannot be explained only by the Th1/Th2.

Abortion, Habitual↗