Search PubMed⌕ Search

Biomedical subjects

T Nagamine

Publications and source records attributed to T Nagamine.

At least 145 records · Page 8Linked to original sources
PubMed1998

Cortical myoclonus: sensorimotor hyperexcitability.

Cortical or cortical reflex myoclonus is characterized by abnormally enlarged cortical somatosensory evoked potentials (giant SEPs), which most likely reflect pathologically hyperexcitable sensorimotor cortex. To clarify the pathogenesis of myoclonus of cortical origin, we simultaneously recorded SEPs and whole head somatosensory evoked magnetic fields (SEFs) following electric stimulation of the median nerve at the wrist in six patients with cortical myoclonus. N20m and enlarged P30m were observed in all patients and were localized at the posterior bank of the central sulcus (Brodmann area 3b of the primary somatosensory cortex). In addition, P25m and N35m components of SEFs were recognized in five and four patients, respectively. P25m component, that is, the magnetic counterpart of P25 in EEG, was the earliest cortical component showing enhancement in patients. Multidipole analysis combined with magnetic resonance imaging (MRI) coregistration revealed that the generators of P25m were in the precentral gyrus in four patients and in the postcentral gyrus in one patient. The second SEFs around 200 msec after the single stimulus were recorded in three patients at area 3b (repetitive SEFs); two of whom showed negative as well as positive myoclonus. The importance of motor cortex for the generation of cortical reflex myoclonus was thus demonstrated. The pathologic features of SEFs suggest abnormal excitability of primary sensorimotor cortex.

Adult↗
PubMed1998

Protective effect of the mold Monascus anka against acetaminophen-induced liver toxicity in rats.

Antioxidant and hepatoprotective actions of the mold Monascus anka (also called Beni-Koji in Japan) against acetaminophen (AAP)-induced liver toxicity were investigated. Serum aspartate aminotransferase and glutathione S-transferase (GST) activities increased by AAP (180 mg/kg, i.p.) treatment were depressed when the Beni-Koji preparation (4 ml/kg, i.p.) was given 15 and 1 hr before AAP administration. The decrease in liver cytosolic GST activity by AAP, reflecting the release of the enzyme into serum, was also blocked by the mold. Cytochrome P450 activity was inhibited by the Beni-Koji preparation. These results suggest that M. anka prevents AAP-induced liver toxicity by both antioxidant action and the inhibition of AAP metabolism.

Acetaminophen↗
PubMed1998

Cloning, sequencing, and expression of an endoglucanase gene from the rumen anaerobic fungus Neocallimastix frontalis MCH3.

A cDNA clone encoding an endo-1,4-beta-glucanase from a rumen fungus, Neocallimastix frontalis MCH3, was isolated. The nucleotide sequence showed that the gene, celA, encoded a multidomain enzyme containing a family 5 catalytic domain and a reiterated sequence that is involved in the association of a multienzyme complex, the cellulosome. The enzyme expressed in Escherichia coli showed the highest activity against carboxymethylcellulose at 40 degrees C and pH 8.5.

Amino Acid Sequence↗
PubMed1998

Quantitative analysis of hepatitis B virus precore mutant in hepatitis type B.

Active liver disease has been detected in chronic hepatitis B after seroconversion from positive HBe antigen to positive anti-HBe antibody. Active replication of HB virus (HBV) containing a precore stop-codon mutation has been implicated in this condition. The usual methods, such as direct sequencing, to characterize the responsible mutant of HBV are not suitable for routine clinical use. Here we employed the competitive mutation site specific assay (CMSSA) to detect precore mutant HBV-DNA in patients with positive HB surface antigen. In patients with HBe antigen, precore mutant HBV-DNA was significantly higher than in patients with HBe antibody. The level of precore mutant HBV-DNA in patients with elevated serum ALT was significantly higher than in patients with normal serum ALT. Sex, age and the level of serum HBV-associated DNA polymerase levels were not correlated with levels of precore mutant HBV-DNA. Ten of 11 negative patients for the precore mutant by polymerase chain reaction followed by restriction fragment length polymorphism assay (PCRRFLP) were positive for the precore mutant by CMSSA. These results suggest that the precore mutant has already emerged in the HBeAg-positive phase as determined by CMSSA, which is more sensitive than PCR-RFLP and is useful for evaluating the clinical course of patients with chronic hepatitis B.

Adult↗
PubMed1997

Movement-related cortical potentials and regional cerebral blood flow change in patients with stroke after motor recovery.

We investigated brain activity during the self-initiated, simple, repetitive hand movement in two patients with hemiparesis due to stroke, who showed relatively good motor recovery, using movement-related cortical potential (MRCP) and regional cerebral blood flow (rCBF) measurements with positron emission tomography (PET). One patient had cortical lesions in the left premotor and left parietal cortices due to cerebral thrombosis, and the other had lesions in the right Rolandic area and several subcortical areas due to the occlusion of the right internal carotid artery. MRCPs in both patients showed lack of the contralateral predominance in amplitude of the late component of slow negative shift prior to the movement of the recovered hand. PET activation study showed increased rCBF in the ipsilateral hemisphere during the movement of the recovered hand. These findings suggest that the ipsilateral hemisphere to the recovered hand may play an important role in the process of motor recovery in patients with cortical infarction, especially within the time period of several hundred ms before the onset of each movement.

Aged↗
PubMed1997

Functional localization of pain perception in the human brain studied by PET.

To elucidate the functional localization and somatotopic organization of pain perception in the human cerebral cortex, we studied the regional cerebral blood flow using positron emission tomography during selective painful stimulation in six normal subjects. Response to a painful stimulus was elicited using a special CO2 laser, which selectively activates nociceptive receptors, to the hand and foot. Multiple brain areas, including bilateral secondary somatosensory cortices (SII) and insula, and the frontal lobe and thalamus contralateral to the stimulus side, were found to be involved in the response to painful stimulation. While our data indicate that the bilateral SII play an important role in pain perception, they also indicate that there is no pain-related somatotopic organization in the human SII or insula.

Adult↗
PubMed1997

Simultaneous recording of epileptiform discharges by MEG and subdural electrodes in temporal lobe epilepsy.

Spontaneous epileptiform discharges were recorded by whole head magnetoencephalography (MEG) and subdural electrodes simultaneously from two patients with medically intractable temporal lobe epilepsy. In one patient whose epileptiform discharges emerged from the lateral temporal lobe, simultaneously recorded MEG could estimate equivalent current dipole reliably near the tumor. The amplitude of the dipole was in proportion not only to the amplitude of epileptiform discharge but also to the number of subdural electrodes involved. In the other patient, MEG detected only a small proportion of epileptiform discharges, even when they were recorded by subdural electrodes from the mesial temporal lobe. It is concluded that the amplitude and the depth of epileptiform discharges would largely affect the sensitivity of dipole localization by MEG.

Adult↗
PubMed1997

Transcatheter arterial embolization-induced bilious pleuritis in a patient with hepatocellular carcinoma.

A 52-year-old man with hepatocellular carcinoma (HCC) was admitted with cough and fever. He had undergone four series of treatments, including transcatheter embolization and chemoembolization with lipiodol and anticancer drugs, over the previous 2 years. Computed tomography demonstrated dilated hepatic ducts, localized necrosis in the right hepatic lobe, and subphrenic abscess. He died of respiratory failure, because of increased effusion of the right pleura, about 3 weeks after admission. Autopsy revealed adhesions in the lower lobes of the right lung, diaphragm, and liver, with granulomas with bile pigment. A fistula was observed from the necrotic regions of the right hepatic lobe to the pleura through the diaphragm. A tumor thrombus in the portal trunk was histologically confirmed as well and moderately differentiated HCC with trabecular arrangement. Direct invasion of HCC with necrotic tissue to the pleura through the diaphragm appeared to have caused the respiratory failure. Although bilious pleuritis is a rare complication of transcatheter arterial embolization (TAE), it should be considered as an adverse effect of TAE in patients with a dilated hepatic duct.

Antineoplastic Agents↗
PubMed1997

Construction of a Fibrobacter succinogenes genomic map and demonstration of diversity at the genomic level.

The genomic cleavage map of the type strain Fibrobacter succinogenes S85 was constructed. The restriction enzymes AscI, AvrII, FseI, NotI, and SfiI generated DNA fragments of suitable size distribution that could be resolved by pulsed-field gel electrophoresis (PFGE). An average genome size of 3.6 Mb was obtained by summing the total fragment sizes. The linkages between the 15 AscI fragments of the genome were determined by combining two approaches: isolation of linking clones and cross-hybridization of restriction fragments. The genome of F. succinogenes was found to be represented by the single circular DNA molecule. Southern hybridization with specific probes allowed the eight genetic markers to be located on the restriction map. The genome of this bacterium contains at least three rRNA operons. PFGE of the other three strains of F. succinogenes gave estimated genome sizes close to that of the type strain. However, RFLP patterns of these strains generated by AscI digestion are completely different. Pairwise comparison of the genomic fragment distribution between the type strain and the three isolates showed a similarity level in the region of 14.3% to 31.3%. No fragment common to all of these F. succinogenes strains could be detected by PFGE. A marked degree of genomic heterogeneity among members of this species makes genomic RFLP a highly discriminatory and useful molecular typing tool for population studies.

Animals↗
PubMed1997

Effects of eicosanoids on lipopolysaccharide-induced ornithine decarboxylase activity and polyamine metabolism in the mouse liver.

BACKGROUND/AIMS: During endotoxic shock, arachidonic acid is released from the inflammatory cell membranes and is metabolized to form eicosanoids, which modify the deleterious effects of lipopolysaccharide (LPS) on liver function. However, it is not known which prostaglandins (PGs) or leukotrienes (LTs) are produced or how they affect the LPS-treated liver. As LPS treatment elevates hepatic ornithine decarboxylase (ODC) activity and affects the polyamine levels of the mouse liver, this study was carried out to examine the effects of eicosanoids and their inhibitors on the induction of ODC activity and polyamine levels in the LPS-treated mouse liver. METHODS: LPS in the presence or absence of other drugs was intraperitoneally administered to 6-week-old mice and the livers were then removed. The hepatic ODC activity, polyamine levels, and level of ODC mRNA were determined. RESULTS: The levels of LPS-induced ODC activity, the putrescine (PUT) and N1-acetylspermidine (A-SPD) were reduced by the administration of PGE1. ODC activity was enhanced by the administration of corticosterone, AA-2414 (an antagonist of thromboxane (TX) A2) and TXB2, whereas the A-SPD level was reduced by corticosterone and AA-2414 treatment. The level of ODC mRNA changed in parallel with the change in ODC activity. CONCLUSIONS: PGE1 may reduce the LPS-induced production of inflammation-accelerating cytokines and reduce the level of ODC activation. Corticosterone and AA-2414 treatment may attenuate the LPS-induced production of eicosanoids, and enhance the LPS-induced ODC activation. It is possible that the eicosanoids produced by LPS treatment inhibit ODC activation during endotoxic shock.

Alprostadil↗
PubMed1997

Dissociation between contingent negative variation (CNV) and Bereitschaftspotential (BP) in patients with parkinsonism.

In order to clarify the generator mechanism of the late component of contingent negative variation (CNV), we compared the late CNV with Bereitschaftspotential (BP) in patients with parkinsonism (Parkinson's disease and progressive supranuclear palsy). In patients with mild symptoms (Hoehn Yahr grade I and II) both the late CNV and BP were clearly seen. In patients with severe symptoms (Hoehn Yahr grade III, IV and V) the BP was normally seen, but the late CNV was significantly smaller or absent (P < 0.001 at Cz) and it was also significantly smaller than that obtained from age-matched normals. In one patient (H-Y grade II) who had normal BP, the late CNV was diminished selectively at the midline area. Since it was reported that the late CNV arises from at least the supplementary motor area (SMA), selective diminution of the late CNV at the midline could be explained by the decreased activity of the SMA in parkinsonism. It was also previously reported that the BP was absent but the late CNV was normally present in a patient with cerebellar efferent lesion (Ikeda et al., 1994). Taken together with the experimental results indicating that movement-related neurons in the putamen behave contingent on external stimuli, it is suggested that subcortical generating mechanism is different for the late CNV and BP although both commonly share at least some cortical generators, and that the basal ganglia are most likely responsible for the generation of the late CNV and the cerebellar efferent system for the generation of the BP.

Adult↗
PubMed1997

Cortical mechanism underlying externally cued gait initiation studied by contingent negative variation.

In order to clarify the cortical mechanism underlying gait initiation, we examined the scalp distribution of the contingent negative variation (CNV) preceding externally cued gait initiation in a simple reaction-time paradigm in 10 healthy right-handed men, and compared the results with the CNV preceding simple foot dorsiflexion. A pair of auditory stimuli was given with an interstimulus (S1-S2) interval of 2 s and gait consisting of at least 3 steps was initiated with the right footstep as fast as possible in response to S2. Brisk dorsiflexion of the right foot was employed as a control task. It was found that the late CNV in the gait initiation task started about 1 s before S2, and was largest at Cz (-9.3 +/- 3.1 microV) without clear asymmetry over the scalp. However, it was ill defined in the parietal area. In the foot dorsiflexion task, the late CNV was maximal at Cz (-7.1 +/- 2.9 microV), and clearly seen also over the parietal area. The late CNV at Cz was significantly (P < 0.01) larger in the gait initiation than in the simple foot dorsiflexion. The amplitude of the late CNV preceding the foot dorsiflexion task was not significantly different between the sitting and the standing posture. In view of the results of previous invasive studies in both humans and animals which showed some frontal areas, including the supplementary motor area (SMA) and the primary motor cortex, as the generators of the late CNV, it is suggested that the cerebral cortex is active in initiation of externally triggered gait in a different way from the simple foot movement, and that bilateral SMAs may play a more important role in gait initiation than in simple foot movement.

Adolescent↗
PubMed1997

Expression and localization of bone morphogenetic proteins (BMPs) and BMP receptors in ossification of the ligamentum flavum.

To clarify the pathogenesis of ossification of the ligamentum flavum (OLF), we examined the expression and localization of bone morphogenetic proteins (BMPs) and their receptors (BMPRs) in the ligamentum flavum of the patients with OLF by immunohistochemical staining and compared them with staining patterns in control patients. The BMPRs appeared extensively in mature and immature chondrocytes around the calcified zone and in spindle-shaped cells and round cells in the remote part from ossified foci in examined tissue of OLF. The ligands for BMPRs, BMP-2/-4 and osteogenic protein-1 (OP-1)/BMP-7, colocalized in OLF patients. In the control cases, expression of BMPs and BMPRs was observed around the calcified zone at the insertion of the ligamentum flavum to the bone, and limited expression was found in the smaller range. Thus, the expression profile of BMPs and BMPRs in OLF patients was entirely different from the control patients, suggesting that BMPs may be involved in promoting endochondral ossification at ectopic ossification sites in OLF, and that ossification activity is continuous in these patients.

Activin Receptors↗
PubMed1997

Prediction of effect of interferon on chronic hepatitis C.

Clinical, pathological, and virological analysis including hypervariable region-1 of hepatitis C virus (HCV) was performed to predict the effect of interferon (IFN) on 41 patients with chronic hepatitis type C. The low virus load, low frequency of the mutation in the hypervariable region-1 as the change of amino acid and high level of serum aminotransferase make one estimate the good effect of IFN on patients with HCV. Mutation in the hypervariable region-1 of HCV measured by fast assay fluorescence single-stranded conformational polymorphism was more frequent in nonresponders to IFN than responders. The most frequently mutated position was amino acid number 406. This indicates that the specific mutation site might affect the response of IFN.

Amino Acid Sequence↗
PubMed1997

Event-related potentials associated with judgment: comparison of S1- and S2-choice conditions in a contingent negative variation (CNV) paradigm.

To elucidate the functional role of association cortex in judgment and decision-making about external stimuli, the scalp topography of contingent negative variation (CNV) recorded in 9 normal volunteers was compared in two settings; dichotomous S1- and S2-choice paradigms using right wrist extension or flexion movement upon S2 as the choice reaction task with an S1-S2 interstimulus interval of 2 s. Two main findings were obtained. First, early CNV in the S1-choice paradigm consisted of a frontal to frontopolar midline negative potential, most likely representing judgment more than orienting response, and a left-sided parietal positive potential, at least partially representing P3b, whereas in the S2-choice paradigm it consisted only of a smaller frontal negative potential shift, most likely representing merely an orienting response. This suggests that the prefrontal and left parietal association cortexes might be active in the judgment and decision-making process. Second, after S2, two positive peaks (334 and 545 ms after S2) were observed at the midline central to left parietal areas only in the S2-choice paradigm. In the S1-choice paradigm, one large negative peak (275 ms after S2) was observed. We postulate that the first peak of the S2-choice paradigm is related to decision making or judgment and that the second peak is related to the following cognitive process. We conclude that at least the prefrontal and parietal association cortexes generate transient potentials accompanying judgment, and possibly decision making.

Adult↗
PubMed1997

Human second somatosensory area: subdural and magnetoencephalographic recording of somatosensory evoked responses.

OBJECTIVE: To investigate somesthetic functions of the perisylvian cortex. METHODS: Somatosensory evoked magnetic fields (SEFs) and somatosensory evoked potentials (SEPs) of the perisylvian cortex were recorded directly from subdural electrodes in a patient with a left frontal brain tumour. RESULTS: The most prominent SEP components after electrical stimulation of the right and left hands and the right foot were double peaked negativity recorded just above the sylvian fissure (latency 80 to 150 ms), respectively (N1a and N1b). Generator sources for the magnetoencephalographic counterparts of those peaks (N1a(m) and N1b(m)) were both localised at the upper bank of the sylvian fissure, and those of N1a(m) were more anteromedially located than those of N1b(m). CONCLUSIONS: These findings suggest the existence of at least two separate somatosensory areas within the human perisylvian cortex.

Adult↗
PubMed1997

Tinnitus remission by lidocaine demonstrated by auditory-evoked magnetoencephalogram. A preliminary report.

An auditory-evoked magnetic field was recorded before and during tinnitus remission induced by an intravenous lidocaine injection. One and 4 kHz probe tones were presented monaurally in four tinnitus patients, and the responses were recorded using a 122-channel magnetometer. Three normal volunteers were also examined as controls. In tinnitus patients, the N100 m peak became sharper, while there was no marked change except for slight reduction in amplitude in normal subjects. Tinnitus remission by lidocaine may be related to attenuation of a masking-like effect of tinnitus on the sound-evoked responses.

Aged↗