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T Mima

Publications and source records attributed to T Mima.

At least 19 recordsLinked to original sources
PubMed2003

Short-lasting impairment of tactile perception by 0.9Hz-rTMS of the sensorimotor cortex.

To test whether low-frequency repetitive transcranial magnetic stimulation (rTMS) of sensorimotor cortex (SM1) has prolonged effects on somatosensory function, eight subjects were given 900 TMS pulses over the left hand SM1 (0.9Hz, 90% of the resting motor threshold) or at sites 3 cm anterior or posterior to it. Tactile threshold of the right hand was increased for a short duration after rTMS over SM1, but two-point discrimination and median nerve SEPs were unaffected after rTMS at any sites.

Adult↗
PubMed2001

Increased synchronization of cortical oscillatory activities between human supplementary motor and primary sensorimotor areas during voluntary movements.

In human, both primary and nonprimary motor areas are involved in the control of voluntary movements. However, the dynamics of functional coupling among different motor areas has not been fully clarified yet. Because it has been proposed that the functional coupling among cortical areas might be achieved by the synchronization of oscillatory activity, we investigated the electrocorticographic coherence between the supplementary motor and primary sensorimotor areas (SMA and S1-M1) by means of event-related partial coherence analysis in 11 intractable epilepsy patients. We found premovement increase of coherence between the SMA proper and S1-M1 at the frequency of 0-33 Hz and between the pre-SMA and S1-M1 at 0-18 Hz. Coherence between the SMA proper and M1 started to increase 0.9 sec before the movement onset and peaked 0.3 sec after the movement. There was no systematic difference within the SMA (SMA proper vs pre-SMA) or within the S1-M1, in terms of the time course as well as the peak value of coherence. The phase spectra revealed near-zero phase difference in 57% (20 of 35) of region pairs analyzed, and the remaining pairs showed inconsistent results. This increase of synchronization between multiple motor areas in the preparation and execution of voluntary movements may reflect the multiregional functional interactions in human motor behavior.

Adolescent↗
PubMed2001

Construction of a series of mutants lacking all of the four major mex operons for multidrug efflux pumps or possessing each one of the operons from Pseudomonas aeruginosa PAO1: MexCD-OprJ is an inducible pump.

We constructed a series of deletion mutants lacking all of the four major mex operons for Mex multidrug efflux pumps or possessing each one of the operons from Pseudomonas aeruginosa PAO1. The drug specificity of MexAB-OprM, MexXY-OprM and MexCD-OprJ was investigated. Surprisingly, we found that the MexCD-OprJ was an inducible pump, inducers of which were tetraphenylphosphonium chloride, ethidium bromide, rhodamine 6G and acriflavine. Fluoroquinolones, chloramphenicol, erythromycin and tetracycline were not inducers although they were substrates of MexCD-OprJ.

Anti-Bacterial Agents↗
PubMed2001

Transient interhemispheric neuronal synchrony correlates with object recognition.

Object recognition might be achieved by the recreation of a meaningful internal image from visual fragments. This recreation might be achieved by neuronal synchronization that has been proposed as a solution for the perceptual binding problem. In this study, we evaluated synchronization between the occipitotemporal regions bilaterally using electroencephalograms during several visual recognition tasks. Conscious recognition of familiar objects spanning the visual midline induced transient interhemispheric electroencephalographic coherence in the alpha band, which did not occur with meaningless objects or with passive viewing. Moreover, there was no interhemispheric coherence when midline objects were not recognized as meaningful or when familiar objects were presented in one visual hemifield. These data suggest a close link between site-specific interregional synchronization and object recognition.

Adult↗
PubMed2001

Information flow from the sensorimotor cortex to muscle in humans.

OBJECTIVES: To investigate the physiologic mechanism of human electroencephalogram-electromyogram (EEG-EMG) coherence, the directed transfer function (DTF) based on a multivariate autoregressive (MVAR) model was computed. METHODS: Fifty-six channel EEG and EMG of the right abductor pollicis brevis muscle during a weak tonic contraction were recorded in 6 normal volunteers. The EEG over the left sensorimotor area and the rectified EMG were used to compute coherence and DTF. RESULTS: EEG-EMG coherence was observed at the peak frequency of 15-29 Hz (mean 18.5 Hz). The peak frequency of DTF from EEG to EMG was 12-27 Hz (mean 17.8 Hz). DTF from EEG to EMG was significantly larger than that from EMG to EEG at 19-30 and 45-50 Hz (P<0.05). CONCLUSIONS: The present findings suggest that the EEG-EMG coupling mechanism for the 19 Hz or higher frequency might differ from that for the lower frequency. Directional information flow from EEG to EMG in the former frequency range likely reflects the motor control command. The finding of the directional information flow from EEG to EMG within the gamma band indicates that 40 Hz EEG-EMG coherence is not specific to the muscle Piper rhythm which is seen only with strong contraction.

Adult↗
PubMed2001

Retrospective analysis of 1502 patients with facial fractures.

A total of 1502 patients with facial fractures treated between 1981 and 1996 were retrospectively analysed. The male: female ratio was 2.8:1 and the largest subgroup of patients was between 10 and 29 years of age. The most common cause of injury was traffic accidents (52%) involving motorcycles, bicycles or automobiles. Other common causes included, in descending order, falls (16.6%), assaults (15.5%) and sports (9.7%). Isolated mandibular fractures were most common (56.9%), followed by isolated midface fractures (25.9%). The percentage of fractures involving both the midface and mandible was 6.7, and that of isolated alveolar fractures was 10.5.

Accidental Falls↗
PubMed2001

Coherence between cortical and muscular activities after subcortical stroke.

BACKGROUND AND PURPOSE: Functional connection between the motor cortex and muscle can be measured by electroencephalogram-electromyogram (EEG-EMG) coherence. To evaluate the functional connection to muscle between contralateral and ipsilateral motor cortices after pyramidal tract lesions, we investigated 6 patients with chronic subcortical stroke. METHODS: High-resolution EEG and EMG of the hand, forearm, and biceps muscles were recorded during 3 tonic contraction tasks: (1) elbow flexion, (2) wrist extension, and (3) power grip. To evaluate the cortical control of EMG, EEG-EMG coherence was computed. RESULTS: EEG-EMG coherence was localized over the contralateral sensorimotor area in all circumstances, and there was no significant coherence at the ipsilateral side. EEG-EMG coherence was significantly smaller on the affected side for the hand and forearm muscles but not for the biceps muscle. CONCLUSIONS: All direct functional connections to muscle after recovered subcortical stroke come from the contralateral motor cortex. The different effects of the lesion on the proximal and distal muscles appear to be associated with the strength of the corticospinal pathway.

Aged↗
PubMed2000

Functional coupling of human right and left cortical motor areas demonstrated with partial coherence analysis.

Although a linear correlation between oscillatory activities in the right and left motor cortices during movements has been shown in monkeys, there has been a debate whether scalp-recorded EEG coherence in human reflects a similar association. By applying partial coherence analysis, we demonstrated that interhemispheric coherence during movements cannot be explained by contamination from the occipital alpha rhythm or common reference signal. A significant increase of net interhemispheric communication in the beta1 band was shown during movements. We propose that the partial coherence method can be a useful tool to measure cortico-cortical functional coupling reliably.

Adult↗
PubMed2000

Doxorubicin, an RNA synthesis inhibitor, prevents vasoconstriction and inhibits aberrant expression of endothelin-1 in the cerebral vasospasm model of the rat.

A vasoconstrictor peptide, endothelin-1 (ET-1), has been identified as one of the causative substances in cerebral vasospasm after subarachnoid hemorrhage. We investigated whether doxorubicin, an RNA synthesis inhibitor, effectively suppresses induction of ET-1 in the rat vasospasm model. Blood was injected around the right femoral artery and the left one was used as an internal control. Seven days later (day 7), diameters of the right femoral arteries narrowed to about 60% and this vasoconstriction was prevented by clinical dose (0.6 mg/kg) or one third of its dose of doxorubicin injected on day 1. Reverse transcriptase-polymerase chain reaction analysis demonstrated that expression of ET-1 mRNA in the vasospastic artery was not detected in doxorubicin-treated rats. It is concluded that doxorubicin effectively inhibits aberrant expression of ET-1 in the vasospasm-destined artery in the rat.

Animals↗
PubMed2000

Argatroban, a thrombin inhibitor, decreased mortality after 10 min of forebrain ischemia in the gerbil.

We investigated whether anticoagulant therapy with heparin or a selective thrombin inhibitor, argatroban, may ameliorate the postischemic cerebral circulation and attenuate mortality after 10 min of forebrain ischemia. Postischemic subcutaneous injection of argatroban (5 mg/kg) significantly attenuated mortality (9.1%) compared with non-treatment (45.5%) during 14 days' observation period. This effect coincided with: (1) increased cortical CBF after reperfusion; (2) attenuation of brain edema; and (3) less severe cell damages in the cerebral cortex. In contrast, nine of the 22 gerbils treated with heparin (830 IU/kg) were found dead on the next day due to massive bleeding in the surgical wound and 13 bleeding-avoided gerbils did not show significant amelioration in mortality (30.8%). These findings suggest that argatroban is an effective anticoagulant for prevention of cell damage after a relatively long forebrain ischemia.

Animals↗
PubMed2000

Enhanced expression and DNA binding activity of two CCAAT/enhancer-binding protein isoforms, C/EBPbeta and C/EBPdelta, in rheumatoid synovium.

OBJECTIVE: To investigate the activation and expression of CCAAT/enhancer-binding proteins (C/EBP), especially C/EBPbeta and -delta, in rheumatoid synovium, and their pathogenic implications in rheumatoid arthritis (RA). METHODS: The activation of C/EBPbeta and -delta was assessed in synovial tissues from patients with RA by electrophoretic mobility shift assay (EMSA); DNA binding activity of C/EBPs was evaluated by measuring EMSA band density. The expression and distribution of C/EBPbeta and -delta in synovial tissues were examined by immunohistochemistry analysis. As a control, synovial tissues from patients with osteoarthritis (OA) were studied. RESULTS: Enhanced DNA binding activity of C/EBPbeta and -delta, 2 major members of the C/EBP family, was detected in synovial tissues from RA patients, while synovial tissues from the patients with OA showed only faint or marginal activity (mean +/- SEM arbitrary units [AU] RA 23.3 +/- 11.7 in RA versus 4.5 +/- 1.3 in OA; P < 0.05). Moreover, the binding activities of the C/EBP proteins were correlated with both serum C-reactive protein levels (r = 0.62, P < 0.05) and synovial interleukin-6 messenger RNA levels (r = 0.60, P < 0.05). In immunohistochemistry studies, C/EBPbeta and -delta were detected predominantly in the rheumatoid synovial lining cells (both CD14+ and CD14- cells). CONCLUSION: C/EBPbeta and -delta may contribute to the pathology of rheumatoid synovitis.

Aged↗
PubMed2000

Tumour necrosis factor alpha (TNF-alpha) interferes with Fas-mediated apoptotic cell death on rheumatoid arthritis (RA) synovial cells: a possible mechanism of rheumatoid synovial hyperplasia and a clinical benefit of anti-TNF-alpha therapy for RA.

To investigate the mechanism of rheumatoid synovial hyperplasia (RASH), the influence of tumour necrosis factor alpha (TNF-alpha) on Fas-mediated apoptotic cell death (Fas-ACD) was examined on cultured rheumatoid synovial cells (RASCs). RASCs were obtained from the synovial tissues of eight patients with rheumatoid arthritis (RA) and SCs from eight patients with osteoarthritis (OA) were used as a control. To examine the influence of TNF-alpha on Fas-ACD, SCs were cultured with anti-Fas antibody (CH11) for 16 h in the absence or presence of different doses of recombinant TNF-alpha. ACD was determined by electron microscopic analysis and the percentage of apoptotic cells was calculated by trypan blue staining. In addition, the expression of Fas and Bcl-2 on RASCs was examined by flow cytometry. As a result, RASCs were more susceptible to Fas-ACD in vitro than OASCs. TNF-alpha interfered with Fas-ACD on RASCs in a dose-dependent manner. Moreover, removal of TNF-alpha activity by a neutralizing anti-TNF-alpha antibody (cA2) restored Fas-ACD. Flow cytometric analysis showed no significant changes in either Fas or Bcl-2 expression on RASCs after the culture with TNFalpha. These results suggest the following: (1) Fas-ACD might be diminished in vivo by local excessive TNF-alpha and this might contribute in part to RASH. (2) The inhibition of Fas-ACD on RASCs by TNF-alpha might not be associated with changes in the expression of Fas or Bcl-2. (3) In addition, considering a magnetic resonance imaging (MRI) finding of marked reduction in the RASH after cA2 treatment, blockade of TNF-alpha activity could restore Fas-ACD in RA synovium, implicating a clinical benefit of anti-TNF-alpha therapy for RA.

Antibodies, Monoclonal↗
PubMed2000

Lipocortin-1 fails to ameliorate ischemic brain edema in the cat.

It has been reported that corticosteroids exert their anti-inflammatory action through de novo synthesis of phospholipase-inhibitory proteins called lipocortins (annexins). We postulated that the following may lessen the effectiveness of corticosteroids on acute ischemic brain edema: 1) lipocortins are induced several hours after administration of steroids; 2) de novo synthesis of lipocortins is suppressed in the ischemic brain; and 3) lipocortins induced systemically do not pass through the blood-brain barrier (BBB) to reach the sites of ischemic edema. To test this hypothesis, we examined whether dexamethasone, given long before ischemia or direct administration of recombinant lipocortin-1, combined with or without BBB opening, ameliorate ischemic brain edema. Three hours before occlusion of the middle cerebral artery (MCA) in the cat, 4 mg/kg of dexamethasone was injected intravenously. The animals were subjected to 4 hours of ischemia. Alternatively, 2 ug/ml (total volume 10 ml) of recombinant human lipocortin-1 (annexin-I) was perfused intermittently into the ischemic focus by catheterization into the MCA. Artificial opening of the BBB was performed by intra-arterial mannitol infusion. None of these strategies demonstrated amelioration of ischemic edema. We conclude that: Dexamethasone and recombinant lipocortin-1 seem unlikely to have robust effects on amelioration of acute ischemic edema.

Animals↗
PubMed2000

Lipocortin-1 fails to ameliorate cold-injury brain edema in the rat.

Based on evidence that corticosteroids exert their anti-inflammatory action via de novo synthesis of phospholipase A2 inhibitory proteins called lipocortins, we examined effects of high dose dexamethasone and recombinant human lipocortin-1 (annexin-I) on cold-injury brain edema in the rat. Since it takes several hours for lipocortins to be induced, dexamethasone (10 mg/kg) was injected intraperitoneally 3 hours before cold injury. Recombinant lipocortin-1 was administered intraventricularly at three different doses (0.01 mg/kg, 0.05 mg/kg, or 0.1 mg/kg: total volume 20 microliters), or via the internal carotid artery at a dose of 10(-7) M (2 ml). To induce cold injury, a liquid-nitrogen-cooled probe was placed on the exposed dura of male Wistar rats (330-370 kg) for 1 minute. Specific gravimetry and/or a wet-dry weighing method were used for measurement of brain edema at 24 or 48 hours after lesion production. In the present study, dexamethasone and recombinant lipocortin-1 failed to attenuate edema formation. The anti-inflammatory effects of dexamethasone or exogenous lipocortin-1 seemed unlikely to affect cold-injury brain edema.

Animals↗
PubMed2000

Human presupplementary motor area is active before voluntary movement: subdural recording of Bereitschaftspotential from medial frontal cortex.

Bereitschaftspotential (BP) was recorded directly from the right supplementary motor area proper (SMA-proper) and its rostral part by chronically implanted subdural electrodes in three patients with intractable focal motor seizure. Cortical electrical stimulation of the SMA-proper revealed the somatotopy as previously reported, and the supplementary negative motor area (SNMA) was identified just anterior to the SMA-proper in two of three cases. In patient 1, eight kinds of simple movements, i.e., left and right middle finger extension, left arm abduction, left and right foot dorsiflexion, left knee extension, tongue protrusion and saccadic eye movement, were studied to record BP. In patient 2, three kinds of movements, i.e., left and right middle finger extension and left foot dorsiflexion, were adopted as movement tasks. In patient 3, four kinds of movements, i.e., left and right middle finger extension and left and right foot dorsiflexion, were adopted. In the SMA-proper, somatotopically distributed BP preceding movements were observed in all three patients. In the SNMA and its rostrally adjacent areas, "SNMA-plus" BPs were generated invariably regardless of the sites of movement. There was no significant difference in the onset time of BPs between the SMA-proper and the SNMA-plus. The present findings suggest that the SNMA-plus is more consistently involved in the preparation for various simple movements than the SMA-proper. This functionally independent region (SNMA-plus) just rostral to the SMA-proper most likely corresponds to a part of the presupplementary motor area which was originally defined in nonhuman primates. Since a part of this area elicited the inhibition of various movements by cortical stimulation, and since it generated BPs regardless of the sites of movement, it may play a higher role in the movement preparatory process than the SMA-proper.

Adult↗
PubMed2000

Aberrant expression of neurotrophic factors in the ventricular progenitor cells of infant congenitally hydrocephalic rats.

OBJECTS: This study was conducted to investigate the roles of neurotrophic factors in the development of hydrocephalus in HTX rats. METHODS: Expressions of brain-derived neurotrophic factor (BDNF), neurotrophin-3 (NT-3), and fibroblast growth factor (FGF)-1 were examined immunohistochemically in the cerebral cortex and ventricular zone of 6-day-old rats with congenital hydrocephalus (HTX rats). In the ventricular zone of hydrocephalic rats, potent BDNF-like immunoreactivity (-LI) and weak but significant signals for NT-3- and FGF-1-LIs were observed. However, no significant signals were detected in non-HTX rats. A small subpopulation of ventricular cells was positive for microtubule-associated protein 2 in HTX and non-HTX rats. The positive cells in the HTX rats had neurites much longer than those in the non-HTX animals, suggesting that some ventricular cells of the hydrocephalics had ectopically differentiated into mature neurons. CONCLUSIONS: This abnormal differentiation may have been responsible for the aberrant expressions of neurotrophic factors. In contrast, the cerebral neuronal layers did not show such prominent alterations in neurotrophic factor expression.

Animals↗