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Biomedical subjects

H Koizumi

Publications and source records attributed to H Koizumi.

At least 37 records · Page 2Linked to original sources
PubMed2001

Serological and immunohistochemical detection of human herpesvirus 8 in Kaposi's sarcoma after immunosuppressive therapy for bullous pemphigoid.

Kaposi's sarcoma (KS) developed in an 87-year-old human immunodeficiency virus-negative woman from Hokkaido island 4 months after oral administration of prednisolone for the treatment of bullous pemphigoid (BP), and rapidly disseminated to almost the entire body within 2 months. The open reading frame (ORF) 59 and ORF73 proteins encoded by human herpesvirus 8 (HHV-8) were detected immunohistochemically in the nuclei of the tumour cells of KS. The protein coded by ORF73, latent protein, was detected in most of the nuclei of the tumour cells, but only a few tumour nuclei were positive for the ORF59 protein, a lytic protein expressed during active infection. The antibodies against both lytic and latent proteins of HHV-8 were detected retrospectively in the serum 4 months before the appearance of KS and before prednisolone therapy had been started. Immunosuppression associated with the treatment for BP possibly activated latent HHV-8 infection and induced the development of KS.

Aged↗
PubMed2001

Activation of visual cortex in REM sleep measured by 24-channel NIRS imaging.

To visualize dreaming brain functions we studied hemodynamic changes in the visual cortex during the transition from non-rapid eye movement (NREM) to rapid eye movement (REM) sleep, using a 24-channel Near-Infrared Spectroscopy (NIRS) imaging method. Results were compared to the activation in visual cortex by visual stimulation during wakefulness. Subjects were four healthy males between 25 and 49 years of age. Five all-night polysomnographic and NIRS recordings were made. Increases in the oxygenated hemoglobin concentration in visual cortex were observed from nine of 14 REM periods. The activated areas were broader during REM sleep than during visual stimulation. These findings suggest that activation of visual cortex in REM sleep might represent dream-related brain activity.

Adult↗
PubMed2001

Tea catechins prevent the development of atherosclerosis in apoprotein E-deficient mice.

Green tea contains various antioxidative flavan-3ols (tea catechins), such as (-)-epigallocatechin gallate (EGCg, the major catechin), which exert potent inhibitory effects on LDL oxidation in vitro and ex vivo in humans. In this study, the antiatherogenic effects of tea catechins were examined in atherosclerosis-susceptible C57BL/6J, apoprotein (apo)E-deficient mice. Male apoE-deficient mice (10 wk old) were fed an atherogenic diet for 14 wk; during that time, one group (tea) was supplied drinking water supplemented with green tea extract (0.8 g/L), and another group (control) was offered the vehicle only. The tea extract consisted of the following (g/100 g): EGCg, 58.4; (-)-epigallocatechin (EGC), 11.7; (-)-epicatechin (EC), 6.6; (-)-gallocatechingallate (GCg), 1.6; (-)-epicatechin gallate (ECg), 0.5; and caffeine, 0.4. The estimated actual intake of tea catechin was 1.7 mg/(d. mouse). Tea ingestion did not influence plasma cholesterol or triglyceride concentrations. Plasma lipid peroxides were reduced in the tea group at wk 8, suggesting that the in vivo oxidative state is improved by tea ingestion. Atheromatous areas in the aorta from the arch to the femoral bifurcation and aortic weights were both significantly attenuated by 23% in the tea group compared with the control group. Aortic cholesterol and triglyceride contents were 27 and 50% lower, respectively, in the tea group than in the control group. These results suggest that chronic ingestion of tea extract prevents the development of atherosclerosis without changing the plasma lipid level in apoE-deficient mice, probably through the potent antioxidative activity of the tea.

Animals↗
PubMed2001

Novel family of sensor histidine kinase genes in Arabidopsis thaliana.

We identified three novel, highly homologous, sensor histidine kinases that possibly function in the plasma membrane of Arabidopsis thaliana, i.e. AHK2, 3 and 4. While AHK2 and 3 are expressed in several organs, AHK4 is mainly expressed in roots. AHK3 suppresses a sensor histidine kinase mutant of yeast.

Amino Acid Sequence↗
PubMed2001

Wavelength dependence of the precision of noninvasive optical measurement of oxy-, deoxy-, and total-hemoglobin concentration.

The precision of noninvasive optical measurement of the concentration changes in oxy-, deoxy-, and total-hemoglobin depends on wavelength. For estimating the precision, we calculated the noise level of the concentration changes as the uncertainty in measurements using several wavelength pairs of light. Seven laser diodes (664-848 nm) were used simultaneously for spectroscopic measurement of brain activity during finger motor stimulation. We also used the analysis of error propagation from the uncertainty in direct measurements of absorbance changes to estimate indirectly the uncertainty of concentration changes. The measurement of the concentration changes made using an 830/664-nm pair are two times (oxy-Hb) and six times (deoxy-Hb) more precise than those made using an 830/782-nm pair.

Biophysical Phenomena↗
PubMed2001

Expression of prolactin gene in spontaneous mammary tumors in aging Fischer 344 rats.

Expression of extra pituitary prolactin (PRL) has been recently reported in the mammary gland. However, spontaneous mammary tumors occurring in aging rats have not been investigated for PRL production. The present study was undertaken to examine the expression of PRL gene in rat mammary tumors spontaneously arisen in rats with pituitary prolactinomas among 130 female Fischer-344 (F-344) rats. The tumors examined were fibroadenoma (adenomatous type) in the 18-month old rat and adenocarcinoma (alveolar/tubular type) in the 21-month old rat. PRL mRNA was examined by solution and in situ reverse transcription-polymerase chain reaction (RT-PCR) method. The predicted amplified products for PRL mRNA were identified in both tumors, and its expression was confirmed to be in the cytoplasm of epithelial cells. The results of the present study showed that PRL gene is expressed in spontaneously arising mammary tumors.

Adenocarcinoma, Bronchiolo-Alveolar↗
PubMed2001

Flow-through chemiluminescence sensor using immobilized oxidases for the selective determination of L-glutamate in a flow-injection system.

A selective and sensitive chemiluminometric flow sensor for the determination of L-glutamate in serum, based on immobilized oxidases such as glutamate oxidase (GOD), uricase (UC) and peroxidase (POD), is described herein. The principle for the selective chemiluminometric detection for L-glutamate is based on coupled reactions of four sequentially aligned immobilized oxidases, UC/POD/GOD/POD in a flow cell. The immobilized UC was employed to decompose urate, which is one of the major interfering components in serum for a luminol-H2O2 chemiluminescence reaction. The H2O2 produced from the UC reaction readily reacted with reducing components, such as ascorbate and glutathione, and then the excess H2O2 was decomposed by the immobilized POD. L-Glutamate in the sample plug was enzymatically converted to H2O2 with immobilized GOD. Subsequently, the peroxide reacts with luminol on the immobilized POD to produce chemiluminescence, proportional to glutamate concentration. The enzymes were immobilized on tresylated poly(vinyl alcohol beads). The immobilized enzymes were packed into TPFE tube (1.0 mm i.d. x 60 cm), in turn, and used as a flow cell. The sampling rate was 30 h-1. The calibration graph for L-glutamate is linear for 20 nM-5 microM; the detection limit (signal-to-noise = 3) is 10 nM.

Ascorbic Acid↗
PubMed2001

[Hand motor cortical area reorganization following cerebral infarction evaluated with functional MRI, near infrared spectroscopic imaging, and transcranial magnetic stimulation].

A 60-year-old, right-handed man suffered from left hemiparesis with upper limb dominance. CT and MRI revealed cerebral infarction of the entire right middle cerebral artery territory. His hemiparesis recovered excellently and residual neurological deficits 6 years later were left hand weakness(grasping power 9 kg vs. 35 kg in the right) and clumsiness. Functional MRI was performed. During right(normal) hand grasping, activation was seen in the left sensorimotor cortex and supplementary motor area. During left(paretic) hand grasping, activation was seen in the left (ipsilateral) sensorimotor cortex, right parietal cortex, and bilateral supplementary motor areas. Near infrared spectroscopic imaging showed similar results. During right hand grasping, left sensorimotor cortex was activated, and during left hand grasping, bilateral sensorimotor cortices were activated with ipsilateral predominance. Transcranial magnetic stimulation of the left motor hand area evoked right hand movement and stimulation of a point near that area evoked ipsilateral left hand muscle movement. Thus, the findings of the three techniques consistently suggest that the recovery of left hemiparesis of this patient was promoted by motor cortical area reorganization including the ipsilateral motor cortex.

Brain↗
PubMed2001

[Noninvasive higher-order brain-function imaging by near-infrared spectroscopy].

The simultaneous position encoding method for optical topography was developed. Each channel has dual-wavelength optics to separately determine the changes in oxy-hemoglobin and deoxy-hemoglobin concentrations around their isobestic points at 805 nm. Part of the incident light penetrates the scalp and skull and is reflected from brain tissues including the cerebral cortex. Any change in the light extinction is mainly due to changes in the oxy-hemoglobin and/or the deoxy-hemoglobin concentration during the activation of a functional area linked to a neuronal activity. Unlike conventional functional imaging methodologies, it can be used for behavioral studies because the flexible optical fibers allow a subject to move, and a very light and compact system can be made. Noninvasive dynamic optical topography has a wide variety of applications from basic science to clinical medicine. Several applications, such as the study of the Broca and Wernicke language areas, the assessment of the dominant hemisphere of the brain, epilepsy focus determination, and sleep studies are reported. We also tested a 14-month-old baby with a extremely abnormal brain.

Brain↗
PubMed2000

Effect of norepinephrine receptors on trigeminal rhythm generation in newborn rats.

N-methyl-D,L-aspartate acid and bicuculline are required to enhance the trigeminal rhythmic activities in an in vitro isolated brainstem block preparation. In this study, we analyzed the effect of norepinephrine on the trigeminal neural circuit underlying rhythmic jaw movements. Rhythmic trigeminal activity is observed in brainstem preparations (inferior colliculus to obex) only following blockade of alpha(2)-adrenoceptors with idazoxan. This observation, combined with the inhibition of rhythm by alpha(2)-adrenoceptor agonists suggests endogenous alpha(2)-adrenoceptor mediated inhibition of trigeminal networks. A complex noradrenergic modulation of trigeminal systems is further supported by the prazosin-sensitive potentiation of rhythm by bath application of the alpha(1)-adrenoceptor agonist phenylephrine.

Adrenergic alpha-1 Receptor Agonists↗
PubMed2000

Direct association of LIS1, the lissencephaly gene product, with a mammalian homologue of a fungal nuclear distribution protein, rNUDE.

LIS1 is a product of the causative gene for type I lissencephaly characterized by a smooth brain surface due to a defect in neuronal migration during brain development and a regulatory subunit of platelet-activating factor acetylhydrolase (PAF-AH). It is also a mammalian homologue of the fungal nuclear distribution (nud) gene, nudF, which controls the migration of fungal nuclei. Using the two-hybrid system, we identified a novel LIS1-interacting protein, rat NUDE (rNUDE), and found that it is a mammalian homologue of another fungal nud gene product, NUDE, and Xenopus mitotic phosphoprotein 43 which is phosphorylated in a cell cycle-dependent manner. rNUDE and the catalytic subunits of PAF-AH interact with the N- and C-termini of LIS1, respectively. However, these proteins, instead of simultaneously binding to LIS1, appeared to bind to LIS1 in a competitive manner. These results suggest that LIS1 functions in nuclear migration by interacting with multiple intracellular proteins in mammals.

1-Alkyl-2-acetylglycerophosphocholine Esterase↗
PubMed2000

Poly(allylamine) beads as selective sorbent for preconcentration of formaldehyde and acetaldehyde in high-performance liquid chromatographic analysis.

Formaldehyde and acetaldehyde in water were determined by preconcentration with poly(allylamine) beads, derivatization with 2,4-dinitrophenylhydrazine (DPH) and analysis by HPLC. Poly(allylamine) beads (0.5 g) were used to adsorb formaldehyde and acetaldehyde at 1.2-150 microg l(-1) and 3.5-220 microg l(-1) from water (1 l). The concentration factor is 50 fold. The aldehydes were eluted and derivatized with 2 mM DPH in 0.5 M H2SO4 (10 ml). The time of analysis was 1 h. The detection limits (S/N=3) for formaldehyde and acetaldehyde were 0.6 and 2 microg l(-1), respectively.

Acetaldehyde↗
PubMed2000

A multimicrospray nebulizer for microwave-induced plasma mass spectrometry

We have developed a nebulizer, called a multimicrospray nebulizer (MMSN), that efficiently introduces analytes for plasma mass spectrometry and plasma emission spectrometry. In this nebulizer, both the sample solution and the nebulizer gas are divided into several streams to produce a multispray. That is, the MMSN is a nebulizer that contains several micronebulization units, each unit including an orifice for passing the nebulizer gas and a capillary for introducing a sample solution. The microspray from each micronebulization unit can be operated at a microliter per minute sample uptake rate to achieve high nebulization efficiency. The multimicrospray nebulizer is capable of introducing more analyte to the plasma compared with a single-orifice micronebulizer, which has a very low sample uptake rate. In this work, an MMSN with three orifices was found to be suitable for microwave-induced plasma mass spectrometry (MIP-MS). The sample uptake rate can be varied within a range of 5-250 microL/min. Therefore, the nebulizer is unique in its ability to deal with various sample volumes and provide high nebulization efficiency. The sensitivity for all elements obtained with the MMSN was higher than that obtained with a conventional concentric nebulizer (CCN), which is difficult to achieve with other types of microintroduction nebulizers. For most elements, the MIP-MS sensitivity was improved about 2-fold at a sample uptake rate of 150 microL/min, a much lower rate than that for the CCN (usually 0.5-1.5 mL/min). The sensitivity for arsenic was improved by a factor of 5. The relative standard deviation was found to be less than 2.0%.

Journal Article↗
PubMed2000

Spontaneous oscillation of oxy- and deoxy- hemoglobin changes with a phase difference throughout the occipital cortex of newborn infants observed using non-invasive optical topography.

We investigated spontaneous changes in the cerebral oxygenation state of infants during quiet sleeping by using a form of multi-channel near-infrared spectroscopy: non-invasive optical topography. Eight infants born at 32-39 weeks were studied at postconceptional term age (38-43 weeks). Spatially synchronized oscillations of changes in the concentration of oxy- and deoxy- hemoglobin ([oxy-Hb] and [deoxy-Hb]) were observed throughout the occipital cortex. Time series analysis based on the theory of non-linear oscillators showed that the mean periods of the oscillation for each infant ranged from 11 to 18 s. The phase lag of [oxy-Hb] relative to [deoxy-Hb] was stable at about 3pi/4. This phase difference may result from interplay between the vasomotion and the oxygen consumption in relation to brain activity.

Female↗
PubMed2000

Topological scenario for stripe formation in manganese oxides

The spin-charge-orbital complex structures of manganites are studied using topological concepts. The key quantity is the "winding number" w associated with the Berry-phase connection of an e(g) electron parallel transported through Jahn-Teller centers, along zigzag one-dimensional paths in an antiferromagnetic environment of t(2g) spins. From these concepts, it is shown that the "bi-stripe" and "Wigner-crystal" states observed experimentally have different w's. Predictions for the spin structure of the charge-ordered states for heavily doped manganites are discussed.

Journal Article↗
PubMed2000

Membrane expression of annexin I is enhanced by calcium and TPA in cultured human keratinocytes.

Annexin I plays an important role in the process of keratinization as a component of the cornified envelope. To elucidate the function of annexin I in keratinization, we investigated the effects of calcium, epinephrine, hydrocortisone, and 12-O-tetradecanoyl phorbol 13-acetate (TPA) on the expression and localization of annexin I in cultured human keratinocytes. Normal human keratinocytes were cultured in serum-free culture medium (0.15 mM calcium) until 70% confluence. After incubation with a higher concentration of calcium (1.8 mM), TPA (100 nM), epinephrine (50 microM), or hydrocortisone (10 microM) for 24 h, the expression of annexin I protein and mRNA was examined using immunofluorescence, Western blot, and Northern blot techniques. Immunofluorescence microscopy showed increased membrane staining of annexin I by calcium, which was inhibited by the addition of epinephrine or hydrocortisone. Western blotting confirmed elevated annexin I on the cell membrane. It was increased in the cell membrane fraction, but not in the cytosol fraction. Interestingly, the mRNA level of annexin I was slightly reduced after incubation with calcium, whereas TPA upregulated both membrane expression and the mRNA level. Secretion of annexin I was increased by TPA but inhibited by calcium. Because calcium and TPA are known to promote keratinization, our data suggest that annexin I expression on the cell membrane is involved in the process of keratinization.

Annexin A1↗