Biomedical subjects

B I Min

Publications and source records attributed to B I Min.

At least 19 recordsLinked to original sources

PubMed2005

Spatial chemical inhomogeneity and local electronic structure of Mn-doped Ge ferromagnetic semiconductors.

We have investigated the chemical distributions and the local electronic structure of potential diluted magnetic semiconductor Ge0.94Mn0.06 single crystals using scanning photoelectron microscopy (SPEM), x-ray absorption spectroscopy (XAS), and photoemission spectroscopy (PES). The SPEM image shows the stripe-shaped microstructures, which arise from the chemical phase separation between the Mn-rich and Mn-depleted phases. The Mn 2p XAS shows that the Mn ions in the Mn-rich region are in the divalent high-spin Mn2+ states but that they do not form metallic Mn clusters. The Mn 3d PES spectrum exhibits a peak centered at approximately 4 eV below E(F) and the negligible spectral weight near E(F). This study suggests that the observed ferromagnetism in Ge1-xMnx arises from the phase-separated Mn-rich phase.

Journal Article↗

PubMed2005

Magnetic and transport properties of the magnetic Polaron: application to Eu1-xLaxB6 system.

To understand the role of the magnetic polaron in magnetic and transport properties of Eu(1-x)LaxB6, we investigate the low carrier density ferromagnetic Kondo lattice model by using the Monte Carlo methods. We demonstrate that the magnetic-polaronic (MP) state with the insulating nature is realized in the phase-separated region in between the ferromagnetic and antiferromagnetic (AFM) states in the phase diagram. The insulating behaviors of EuB6 just above T(C) and of Eu(1-x)LaxB6 with 0.05<x<0.2 are well explained by MP states in the paramagnetic and the AFM background, respectively. The Eu vacancy plays a crucial role in forming the bound magnetic polaron and so producing the resistivity peak in EuB6. By applying the weak magnetic field, the AFM metallic ground state is destroyed into the MP state, but the metallic behavior is restored by the strong magnetic field, as is observed for Eu(1-x)LaxB6 with 0.2< x < 0.3.

Journal Article↗

PubMed2004

Electronic structures of RTe2 (R = La,Ce): a clue to the pressure-induced superconductivity in CeTe1.82.

Electronic structures of RTe2 (R=La,Ce) have been investigated by using the local spin density approximation (LSDA) and the LSDA + U (U: on-site Coulomb interaction) band methods. Both LaTe2 and CeTe2 show the very similar Fermi surface nesting features along the [100] direction, which drive the charge-density wave (CDW) instability in the Te(1) sheets. The contribution near E(F) from Ce 4f states is negligible in agreement with the measured ARPES spectra. In the semimetallic CDW-distorted RTe2, both Te vacancy and pressure induce the charge transfer from Te(1) 5p to R 5d states, producing the enhanced density of states at E(F). We suggest that these increased self-doped Te(1) 5p hole carriers are responsible for the pressure-induced superconductivity in nonstoichiometric CeTe1.82.

Journal Article↗

PubMed2002

Modulation of natural killer cell activity affected by electroacupuncture through lateral hypothalamic area in rats.

Electroacupuncture (EA) has been reported to modulate natural killer cell (NK cell) activities. Also it is well known that hypothalamus directly mediates the effects of EA on analgesia. Especially lateral hypothalamic area (LHA) is related to splenic NK cell activities. In order to investigate the relationship between hypothalamus and effects of EA on NK cell activity, lesions have been made bilaterally at LHA of Spraque-Dawley rats. Subsequently, NK cell cytotoxities of normal and lesioned rats were measured with (51)Cr release immunoassay after EA stimulation for 2 and 14 days. NK cell activity of EA group was significantly higher than sham group. In addition, lesions abolished effects of EA on NK cell activity. These results strongly suggest that LHA is closely related to increase of NK cell activity induced by EA.

Animals↗

PubMed2001

Role of protein kinase C in opioid modulation of glycine-gated Cl(-) current in rat periaqueductal gray neuron.

The Role of protein kinase C in the modulatory effect of a mu-opioid receptor agonist, [D-Ala(2),N-Me-Phe(4),Gly(5)-ol]enkephalin (DAMGO), on the glycine-gated Cl(-) current was examined in acutely dissociated rat periaqueductal gray neurons. Using the nystatin-perforated patch-clamp technique, the neurons were voltage-clamped at -60 mV. The glycine-gated Cl(-) current (I(Gly)) was sensitive to strychnine. On pretreatment with 1 microM DAMGO, the 30-microM glycine response increased with time and showed a maximum amplitude of 209+/-37% of control. After a protein kinase C activator, phorbol-12-myristate-13-acetate (PMA, 0.1 microM) as pretreatment, I(Gly) increased to 138+/-6% of control. The DAMGO potentiation of I(Gly) was not altered by coapplication with PMA. Although protein kinase C inhibitors, chelerythrine (3 microM) and 2-[1-(3-dimethylaminopropyl)indol-3-yl]-3-(indol-3-yl) maleimide (GF109203X, 1 microM), did not alter I(Gly), the DAMGO-induced potentiation of I(Gly) was reduced to 161+/-21% or 164+/-31% of the control after coapplication with chelerythrine or GF109203X, respectively. These results indicate that the potentiation of I(Gly) by a mu-opioid receptor agonist is partly mediated by activation of protein kinase C.

Alkaloids↗

PubMed2001

Antagonizing effect of protein kinase C activation on the mu-opioid agonist-induced inhibition of high voltage-activated calcium current in rat periaqueductal gray neuron.

Opioids have been thought to induce analgesia by activating the descending pain control system, especially at the level of periaqueductal gray, and regulate the neurotransmitter release through the inhibition of calcium channel. In the present study, the modulatory effects of protein kinase C and protein kinase A on the mu-opioid agonist-induced inhibition of the high-voltage activated calcium current were examined in the acutely dissociated rat periaqueductal gray neurons with the nystatin-perforated patch-clamp technique. Among 505 neurons tested, the barium current passing through the high-voltage activated calcium channels of 172 neurons (34%) were inhibited by 32+/-3% with the application of an mu-opioid agonist, [D-Ala(2),N-MePhe(4),Gly(5)-ol]-enkephalin (DAMGO, 1 microM). The barium currents itself and the DAMGO-induced inhibitory effects were not affected by the application of either an adenylate cyclase activator (forskolin, 1 microM) or a protein kinase inhibitor (staurosporin, 10 nM) for 2 min. The DAMGO inhibition was completely and irreversibly antagonized by the application of a protein kinase C activator, phorbol-12-myristate-13-acetate (PMA, 1 microM) for 2 min without any alteration of the barium current itself. However, the antagonizing effect of PMA was completely abolished by the application of 10 nM staurosporin for 2 min. After then, PMA did not show the antagonizing effect any more. Inversely, when staurosporin was applied before PMA, the antagonizing effect of PMA was also not shown. These results demonstrate that the mu-opioid agonist-induced inhibition of the periaqueductal gray neuronal high-voltage activated calcium current can be antagonized by protein kinase C activation. This finding may provide us a significant clue to understand the action mechanism of opioid-induced analgesia in the periaqueductal gray.

Analgesics, Opioid↗

PubMed2001

Analgesic effect of the acupuncture using the method of quick insertion and withdrawal of the needle in rats.

The method of quick insertion and withdrawal of the needle (QIW) in acupuncture is a technique of stimulation not retaining the needle in the acupuncture point. We examined the analgesic effects of five different types of QIW along with the changes of stimulation quantity, time, and depth, and then compared the analgesic effect of the most effective QIW to that of plain acupuncture (PA). When tail-flick latency values between the strongest QIW-I group and PA group were compared, there was no significant difference (analyzed by t-test). These results indicate that QIW technique has an analgesic effect similar to PA technique and that the conditions, which for the QIW-I was shown the most effective analgesia, are a duration of 5 s at intervals of 1 s and at the depth of 3 mm.

Acupuncture Therapy↗

PubMed2001

5-HT1A receptor-mediated activation of G-protein-gated inwardly rectifying K+ current in rat periaqueductal gray neurons.

5-hydroxytryptamine (5-HT) has been reported to modulate analgesia produced by opioids or electrical stimulation of the periaqueductal gray (PAG). 5-HT increases K+ conductance and inhibits the firing activity of the PAG neurons. We examined the electrophysiological and pharmacological characteristics of the K+ current involved in 5-HT-induced hyperpolarization of dissociated rat PAG neurons. Among the neurons tested, 5-HT activated inward K+ currents in 30-40%, whilst the remaining 60-70% did not respond to 5-HT. 5-HT activated an inwardly rectifying K+ current (I5-HT) in a concentration- and voltage-dependent manner. I5-HT was mimicked by a 5-HT1A receptor selective agonist, 8-OH-DPAT, and was reversibly blocked by a 5-HT1A receptor antagonist, piperazine maleate, but not by a 5-HT2 receptor antagonist, ketanserin. I5-HT was sensitive to K+ channel blockers such as quinine and Ba2+, but insensitive to 4-aminopyridine, Cs+ and tetraethylammonium. I5-HT was inhibited by GDP(beta)s and was irreversibly activated by GTP(gamma)s. I5-HT was significantly suppressed by N-ethylmaleimide and pertussis toxin, but not by cholera toxin. Second messenger modulators such as staurosporin, forskolin, and phorbol-12-myristate-13-acetate did not alter I5-HT. The present study indicates that 5-HT-induced hyperpolarization of the PAG neurons results from activation of the pertussis toxin-sensitive G-protein-coupled inwardly rectifying K+ currents through 5-HT1A receptors.

Animals↗

PubMed2001

Electroacupuncture may relax the sphincter of Oddi in humans.

BACKGROUND: This study was designed to evaluate the effects of electroacupuncture on sphincter of Oddi (SO) motility in humans and to associate the manometric findings with cholecystokinin (CCK) plasma levels. METHODS: Eleven patients (M:F = 5:6) with various kinds of biliary disorders were enrolled. SO motility was monitored with conventional low-compliance, continuous perfusion technique at ERCP (n = 9) or via percutaneous transhepatic cholangioscopy (n = 2). After baseline monitoring for phasic wave contractions of SO, electroacupuncture was applied at a specific acupoint GB 34. A nonspecific acupoint 5 cm away from GB 34 was selected as a control. Manometric parameters of the SO were also measured in 6 subjects during stimulation of the control acupoint. CCK plasma levels were measured during electroacupuncture stimulation. RESULTS: All manometric parameters including basal pressure, amplitude, frequency, and duration of phasic wave contractions of the SO were significantly decreased (p < 0.05) during electroacupuncture stimulation. The inhibition of SO contractility was accompanied by increased CCK plasma levels. After discontinuation of electroacupuncture stimulation, restoration of amplitude and duration to basal conditions was noted. A tendency toward return of SO basal pressure and contractile frequency to baseline was also observed. Stimulation of the control acupoint did not affect SO contractility. CONCLUSION: Electroacupuncture stimulation of acupoint GB 34 resulted in reversible inhibition of SO contraction in humans. The response of SO to electroacupuncture stimulation may be mediated by some neurohormonal mechanisms including CCK release.

Adult↗

PubMed2000

The difference between electroacupuncture only and electroacupuncture with manipulation on analgesia in rats.

Plain acupuncture uses manipulation (rotation or varying the depth of insertion of the needle) to increase its effect. However, in commonly used electroacupunture (EA), variable manipulations have not been used. This study was performed to investigate the possibility of an increase in analgesic effect by adding manipulation to EA. The pain index used was the Tail-Flick latency (TFL) of the rat, which was lightly anesthetized with thiopental sodium (intraperitoneally). Four types of manipulation were used. Rotation and varying the depth of the needle (RN and VN) was employed using two different types of manipulation during each 20 min stimulation of EA. Each manipulation persisted for 1 min out of every 5 min (long - duration and long - interval: LDLI) or 12 s every 1 min (short - duration and short interval: SDSI). EA produced an increase in TFL; peak value was 49.7+/-12.2% of the pre - EA and occurred immediately after cessation of 20 min of EA stimulation. Performing RN or VN combined with EA also increased TFL more than just EA and a greater peak increase in TFL was observed with a SDSI - RN and SDSI - VN as compared to a LDLI - RN and LDLI - VN (77.5+/-13.8, 79.2+/-19.8 and 67.3+/-14.0%, 65.6+/-23.7% of the pre - EA, respectively). These results indicate that manipulation combined with EA produces a more potent antinociception than when only EA is applied.

Acupuncture Analgesia↗

PubMed2000

Chronological effects of atherogenic diets on the aorta, liver and spleen of rabbits.

To investigate the temporal progression of atherogenesis on the aorta and involvement of the monocyte-macrophage system in the liver and spleen, we fed 74 rabbits with high fat (14 or 7 gm%) and cholesterol (2 and 1%) diets for 4 to over 24 weeks. Using both light and electron microscopies, we found that the fibro-fatty areas on the luminal surface of aortas was spread over along the feeding time dependently. The fat deposits also in the liver and spleen worsened depending on the time of feeding the atherogenic diets. Not only monocyte-derived foam cells, but also parenchymatous cells in the liver and spleen involved become fat-laden cells. According to these results, we propose that there are three stages: 1) the primary seeding, 2) the intermediate maturing and 3) the advanced periods. These periods may play very important roles in designing the management and treatment of atherosclerotic patients.

Animals↗

PubMed1999

Inhibitory effects of electroacupuncture on stress responses evoked by tooth-pulp stimulation in rats.

The mechanism of electroacupuncture (EA) on the stress responses induced by tooth-pulp stimulation was investigated in anesthetized adult female Sprague-Dawley rats. The Hoku point in the Chinese meridian was used for acupuncture stimulation. Constant rectangular current (1 mA) pulses of 5-ms duration were delivered at 3 Hz through a pair of needles for 15 min. As for stress response indexes, we have monitored changes in arterial blood pressure and the levels of blood catecholamines, corticosterone, and ACTH. Arterial blood pressure was increased by high frequency stimulation (0.1 mA, 0.5 ms, 100 Hz for 15 s) of tooth-pulp in the control condition. After EA, we did not observe the same responses of the arterial blood pressure changes with the same stimuli. The tooth-pulp stimulation increased the concentrations of plasma norepinephrine (NE), epinephrine (E), dopamine (DA), corticosterone, and ACTH significantly from the levels of those before stress. After treatment with EA, the stress-induced increase in NE, DA, corticosterone, and ACTH but not the rise in E, were inhibited. When naloxone, an opioid antagonist, was administered intraperitoneally before EA, the effects of EA on stress responses were reduced. In this study, it can be suggested that EA has not only an analgesic effect but also suppressive effects on the stress responses primarily through the mediation of an endogenous opioid.

Adrenocorticotropic Hormone↗

PubMed1999

Mu-opioid agonist-induced activation of G-protein-coupled inwardly rectifying potassium current in rat periaqueductal gray neurons.

The characteristics of the inwardly rectifying K+ current activated by a mu-type opioid agonist, D-Ala2,N-MePhe4,Gly5-ol-enkephalin (DAMGO), were examined in the acutely dissociated rat periaqueductal gray neurons using the nystatin-perforated and the conventional whole-cell recording modes under voltage-clamp conditions. DAMGO activated inward currents in a concentration- and voltage-dependent manner. The DAMGO-induced current was an inwardly rectifying K+ current (I(DAMGO)) which was sensitive to K+ channel blockers, quinine and Ba2+ but insensitive to Cs+ and tetraethylammonium. In the conventional whole-cell clamp mode, guanosine 5'-O-(2-thiodiphosphate) trilithium salt (GDPbetas, 0.4 mM) inhibited the amplitude of I(DAMGO) to 28% of that of the initial current. After the intracellular perfusion with guanosine 5'-O-(3-thiotriphosphate) tetralithium salt (GTPgammas, 0.4 mM) for 1 min, the first application of DAMGO irreversibly activated I(DAMGO). By the extracellular application of N-ethylmaleimide at a concentration of 50 microM for 2 min, I(DAMGO) was completely abolished. When a conventional whole-cell patch was made with a patch-pipette containing 1 microg/ml of pertussis toxin together with 1 mM of beta-nicotinamide adenine dinucleotide, I(DAMGO) gradually declined to about 41% of its initial amplitude. The extracellular application of second messenger modulators including protein kinase inhibitor (staurosporin), protein kinase A activators (forskolin, 3-isobutyl-l-methyl-xanthine and dibutyryladenosine 3'5'-cyclic monophosphate) and protein kinase C activators (phorbol-12-myristate-13-acetate and 1-oleoyl-2-acetyl-sn-glycerol) had no effect on I(DAMGO). These results suggest that (i) DAMGO-activated inwardly rectifying K+ current is mediated by pertussis toxin-sensitive guanine nucleotide binding proteins (G-proteins); (ii) the types of G protein involved in I(DAMGO) are Gi and/or Go; and (iii) the G-proteins exert their roles in I(DAMGO) without any mediation of the second messenger systems.

Animals↗

PubMed1998

New findings of the correlation between acupoints and corresponding brain cortices using functional MRI.

A preliminary study of the correlation between acupuncture points (acupoints) for the treatment of eye disorders suggested by ancient Oriental literature and the corresponding brain localization for vision described by Western medicine was performed by using functional MRI (fMRI). The vision-related acupoint (VA1) is located in the lateral aspect of the foot, and when acupuncture stimulation is performed there, activation of occipital lobes is seen by fMRI. Stimulation of the eye by directly using light results in similar activation in the occipital lobes by fMRI. The experiment was conducted by using conventional checkerboard 8-Hz light-flash stimulation of the eye and observation of the time-course data. This was followed by stimulation of the VA1 by using the same time-course paradigm as visual light stimulation. Results obtained with 12 volunteers yielded very clean data and very close correlations between visual and acupuncture stimulation. We have also stimulated nonacupoints 2 to 5 cm away from the vision-related acupoints on the foot as a control, and activation in the occipital lobes was not observed. The results obtained demonstrate the correlation between activation of specific areas of brain cortices and corresponding acupoint stimulation predicted by ancient acupuncture literature.

Acupuncture Points↗

PubMed1996

Modulation of glycine-induced chloride current in acutely dissociated rat periaqueductal gray neurons by mu-opioid agonist DAGO.

Effect of a mu-opioid agonist (D-Ala2,N-MePhe4,Gly5-ol-enkephalin, DAGO), on glycine (Gly)-induced chloride current (IGly) was investigated in the periaqueductal gray (PAG) neurons acutely dissociated 1-2-week-old Wistar rats by the use of nystatin-perforated patch recording configuration under voltage-clamp condition. At a holding potential (VH) of -40 mV, DAGO caused a sustained potentiation of IGly at the low concentrations (10(-6)-10(-5) M) but reduced slightly the Gly response at the high concentration (10(-4) M). The reversal potential of IGly was equal to the Cl- equilibrium potential (ECl) and was not changed in the presence of 10(-6) M DAGO. The 10(-5) M Gly response was inhibited by the simultaneous treatment of forskolin and 3-isobutyl-1-methylxanthine (IBMX). H-89, a protein kinase A (PKA) inhibitor, increased the 10(-5) M Gly response but had little effect on the 10(-4) M Gly response. DAGO increased 10(-5) M Gly response in the presence of forskolin and IBMX but, not more than in the absence of forskolin and IBMX. The 10(-5) M Gly response augumented by DAGO was not affected by adding H-89. The present results suggest that the glycine-induced chloride current is cAMP dependent and is inhibited by PKA, and that the potentiation of the glycine response by DAGO is also cAMP dependent and is due to the inhibition of PKA as that of H-89. We conclude that the potentiation of glycine response by DAGO is mediated by an inhibition of cAMP-dependent PKA in the PAG neurons.

Animals↗

PubMed1989

Responses of rat lateral hypothalamic neuronal activity to fastigial nucleus stimulation.

1. The aim of this study was investigation of neuronal mechanisms underlying inputs from the fastigial nucleus (FN) to the lateral hypothalamic area (LHA). 2. In male anesthetized rats, 295 extracellular and 82 intracellular recordings of LHA responses to electrical stimulation of the FN, which elicited stimulus-locked pressor responses, were examined. 3. Contralateral FN stimulation evoked three types of responses in 48% of spontaneously firing LHA neurons: inhibition with 11 +/- 6 (SD) ms latency followed by excitation (30%), excitation with 15 +/- 12.5 ms latency (14%), and excitation followed by inhibition with 6 +/- 4 ms latency (4%). 4. Contralateral FN stimulation after transection of the inferior cerebellar peduncle (ICP), which resulted in a substantial fall of the fastigial pressor response, also evoked the three types of responses. These responses were unaffected by transection of the ICP. 5. Neuronal activity was recorded intracellularly from 82 LHA neurons, of which 36 (44%) responded to FN stimulation. Of the 36 neurons, 24 showed inhibitory postsynaptic potentials (IPSPs) with a mean latency of 7.5 +/- 2 ms. Of the 24 neurons, 16 were checked for change in IPSP latency with stimulus intensity, and 11 were considered to be monosynaptically connected since their latencies were constant when FN stimulation intensity was changed. The remaining 12 exhibited excitatory postsynaptic potentials (EPSPs) with a longer latency of 10.5 +/- 3 ms, which indicated polysynaptic conduction. The reversal potentials of the IPSP and EPSP were estimated to be about -77 mV and -13 mV, respectively. 6. Most glucose-sensitive neurons (78%), which were identified by their inhibition in response to electrophoretically applied glucose, were inhibited by FN stimulation, whereas only 7% of the glucose-insensitive neurons responded to such stimulation. 7. From the results, it was concluded that LHA neurons receive inhibitory monosynaptic and excitatory polysynaptic inputs from the FN via the superior cerebellar peduncle. These connections may contribute to hypothalamic modulation of feeding behavior.

Animals↗

PubMed1989

[Clinical study of mandibular condyle injury].

Mandibular condyle fractures develop frequently and show the variable type of injury and complication. New opinions have emerged from recent investigation into condylar fractures. The author investigated 246 patients with condylar fractures who visited SNUDH from January 1980 to August, 1988, 8. with regard to clinical and treatment aspects, area and displacement of fractures, associated teeth injury and other body injury, complications. At last I have got the following results. 1. The incidence to condylar fractures in a series of 765 mandibular fractures may be as high as 32.2%. 2. The male patients are 3 times more than female patients. The highest frequency was recorded in the group 21-30 years of age. (34.1%). 3. Falls caused the greatest number of condylar fractures (45.2%) and next was in assult (25.6%), traffic accidents (22.4%). 4. Unilateral condylar fractures were present in 74.8%, giving a left: right ratio of 1.2:1. In cases of unilateral fracture, subcondylar fractures were by far the commonest (32.9%) but in cases of bilateral fracture, condylar neck fractures were by far the commonest. In children under 15 years of age, condylar neck fractures were more common but in patients over 16 years of age, subcondylar fractures were common. 5. Anteromedial fracture dislocations were by far the commonest (20.3%). In children under 15 years of age, fracture deviations were common but in patients over 16 years of age, fracture displacements were common. 6. 44.7% of patients with condylar fractures sustained the teeth injuries. Teeth fractures were by far the commonest. 7. Single condylar fractures showed a frequency of 30.5%. Of the concomitant fractures elsewhere in the mandible, symphysis fractures were by far the commonest (54.1%). 8. Associated other body injuries showed a frequency of 28.0%. Of them, head injuries were by far the commonest. 9. The mean interval from injury to treatment was 14.3 days. Of the treatment of condylar fractures, open reduction was by far the commonest (70.3%). Closed reduction comprised 19.9% and functional therapy comprised 8.5%. 10. In 67 patients with possible follow up period, the following complications were developed, two ankylosis, anterior open bite, mouth opening limitation, mouth opening deviation.

Adolescent↗

PubMed1988

Internal and external information processing by lateral hypothalamic glucose-sensitive and insensitive neurons during bar press feeding in the monkey.

Single neuron activities in the lateral hypothalamic area (LHA) were recorded during bar press feeding task in the monkey. First registered neurons were sorted into 2 groups, glucose-sensitive (GS) and glucose-insensitive (GIS) neurons, depending on their glucose sensitivity. The firing variations to feeding, electrophoretically applied catecholamines and opiate, and to odor and taste stimuli were investigated. GS neurons responded to dopamine, noradrenaline and morphine more often than GIS neurons. In feeding task GS neurons responded during bar press (BP) and reward (RW) periods with long-lasting inhibition of firing and at cue tone (CT) with transient inhibition, while GIS neurons responded during BP and RW periods mainly with excitation and at cue light (CL) with excitation. A majority of GS neurons responded to both odor and taste stimuli more often than GIS neurons. Data suggest that these two kinds of neurons in the LHA may be involved in different functional aspects of feeding: GS neurons, mainly in internal information processing and reward mechanism, and GIS neurons, in external information processing and motor aspects.

Action Potentials↗