Biomedical subjects

Atsuko Suzuki

Publications and source records attributed to Atsuko Suzuki.

At least 19 recordsLinked to original sources

PubMed2007

Rare carotenoids, (3R)-saproxanthin and (3R,2'S)-myxol, isolated from novel marine bacteria (Flavobacteriaceae) and their antioxidative activities.

We isolated three orange or yellow pigment-producing marine bacteria, strains 04OKA-13-27 (MBIC08261), 04OKA-17-12 (MBIC08260), and YM6-073 (MBIC06409), off the coast of Okinawa Prefecture in Japan. These strains were classified as novel species of the family Flavobacteriaceae based on their 16S rRNA gene sequence. They were cultured, and the major carotenoids produced were purified by chromatographic methods. Their structures were determined by spectral data to be (3R)-saproxanthin (strain 04OKA-13-27), (3R,2'S)-myxol (strain YM6-073), and (3R,3'R)-zeaxanthin (strains YM6-073 and 04OKA-17-12). Saproxanthin and myxol, which are monocyclic carotenoids rarely found in nature, demonstrated significant antioxidative activities against lipid peroxidation in the rat brain homogenate model and a neuro-protective effect from L-glutamate toxicity.

Animals↗

PubMed2006

Association analysis of SOD2 variants with methamphetamine psychosis in Japanese and Taiwanese populations.

SOD2 (superoxide dismutase 2) plays a crucial role in protecting the cells against damage caused by free radicals, by catalyzing their detoxification. On the other hand, cell damage caused by free radical generation following methamphetamine administration has been postulated as one of the possible pathophysiological mechanisms for methamphetamine psychosis. Hence, we investigated the association of SOD2 polymorphisms with the development of methamphetamine psychosis, in two independent populations of Japan and Taiwan. We recruited 116 patients with methamphetamine psychosis and 189 controls in Japan, and 135 patients with methamphetamine psychosis and 204 controls in Taiwan. The methamphetamine group was divided into two clinical subtypes: a transient type of psychosis (i.e., good prognosis) and a prolonged type of psychosis (i.e., poor prognosis), according to the course of the manifestation of psychosis. With reference to the genotypic and allelic frequencies of Ala/Val functional polymorphism in exon 2, we found significant differences between individuals with prolonged methamphetamine psychosis and control samples from Japan and Taiwan in the genotypic (P value 0.014 and 0.016, respectively) and in the allelic (P value 0.004 and 0.047, respectively) frequencies. Our results suggest that Ala/Val polymorphism of the SOD2 gene could be associated with the risk of developing methamphetamine psychosis.

Adolescent↗

PubMed2006

Responses of acetylcholine release and regional blood flow in the hippocampus during walking in aged rats.

Walking produced increases in both the extracellular acetylcholine level and regional blood flow in the hippocampus in aged rats 26-29 months old. The present results in aged rats were compared with our previous data in young adult rats (Nakajima et al., 2003), and it was found that both the acetylcholine and blood flow responses in the hippocampus were well maintained in aged rats.

Acetylcholine↗

PubMed2006

The articulo-cardiac sympathetic reflex in spinalized, anesthetized rats.

Somatic afferent regulation of heart rate by noxious knee joint stimulation has been proven in anesthetized cats to be a reflex response whose reflex center is in the brain and whose efferent arc is a cardiac sympathetic nerve. In the present study we examined whether articular stimulation could influence heart rate by this efferent sympathetic pathway in spinalized rats. In central nervous system (CNS)-intact rats, noxious articular movement of either the knee or elbow joint resulted in an increase in cardiac sympathetic nerve activity and heart rate. However, although in acutely spinalized rats a noxious movement of the elbow joint resulted in a significant increase in cardiac sympathetic nerve activity and heart rate, a noxious movement of the knee joint had no such effect and resulted in only a marginal increase in heart rate. Because this marginal increase was abolished by adrenalectomy suggests that it was due to the release of adrenal catecholamines. In conclusion, the spinal cord appears to be capable of mediating, by way of cardiac sympathetic nerves, the propriospinally induced reflex increase in heart rate that follows noxious stimulation of the elbow joint, but not the knee joint.

Adrenalectomy↗

PubMed2006

Magnetic resonance coronary angiography to evaluate coronary arterial lesions in patients with Kawasaki disease.

We evaluated the efficiency of non-invasive magnetic resonance coronary angiography in detecting coronary arterial lesions in 106 patients, aged from 4 months to 37 years, with a median of 13 years, with Kawasaki disease. Non-contrast enhanced, free-breathing magnetic resonance coronary angiographic studies using both the steady-state free precession technique, namely bright blood imaging, and navigator-echo proton density weighted black blood imaging, so-called black blood imaging, were performed in all the patients. Conventional X-ray coronary angiography was performed in 70 patients with coronary arterial lesions. We observed 97 aneurysms, 17 dilatations, 17 occlusions, 18 localized stenoses and 10 recanalized vessels, and we clarified their unique pattern of images on magnetic resonance coronary angiography. The differences in size of the aneurysms as seen on X-ray coronary angiography and bright blood imaging was mean 0.0, and the 95% confidence interval was from -1.4 to 1.5 on the Bland-Altman plots. With bright blood imaging, the sensitivity of occlusion and localized stenosis based on X-ray angiography was 94.2% and 97.2%, specificity was 99.5% and 97.2%, and negative-predictive value was 99.5% and 97.2%, respectively. Black blood imaging provided remarkable visualization of the thickened intima of aneurysms, and/or thrombus, in 38 lesions. We conclude that magnetic resonance coronary angiography can visualize all types of lesions due to Kawasaki disease in patients of all ages, and that it is useful to reduce the number of times X-ray angiography needs to be performed in patients with Kawasaki disease.

Adolescent↗

PubMed2006

An association study between catechol-O-methyl transferase gene polymorphism and methamphetamine psychotic disorder.

OBJECTIVE: A series of methamphetamine psychosis reveals two kinds of clinical courses of methamphetamine psychosis: transient type and prolonged type. Furthermore, paranoid psychosis sometimes recurs without methamphetamine reuse, referred to as spontaneous relapse. Dysfunction of central dopaminergic neurotransmission has been implicated in the pathogenesis of these psychiatric states. Catechol-O-methyl transferase appears to play a unique role in regulating synaptic dopaminergic activity. This study aimed to investigate whether a functional polymorphism of the catechol-O-methyl transferase gene would be involved in the development of these psychiatric states. BASIC METHODS: We examined the functional polymorphism of val 158 met (catechol-O-methyl transferase) in 143 patients with methamphetamine psychosis and 200 healthy controls in Japan. The patients were divided into subgroups by several characteristic clinical features. MAIN RESULTS: We found a significant difference in the catechol-O-methyl transferase allele frequency between patients with spontaneous relapse and the controls (P=0.018, odds ratio=1.67). Odds ratio implied that the patients with spontaneous relapse had a nearly 1.7-fold higher rate of the low activity alleles (met) than the controls. CONCLUSIONS: Our results indicate that the met allele frequency of the catechol-O-methyl transferase is associated with patients who experienced methamphetamine psychosis and spontaneous relapse, suggesting that patients with a met allele appear to be at increased risk of an adverse response to methamphetamine.

Adult↗

PubMed2006

Global gene expression in mouse vaginae exposed to diethylstilbestrol at different ages.

Estrogens regulate proliferation and differentiation of cells in target organs such as the female reproductive tract. In mature mice, estrogens stimulate cell proliferation, whereas ovariectomy results in atrophy of the female reproductive tract. In contrast, perinatal exposure to estrogens, including diethylstilbestrol (DES), induces persistent, ovary-independent vaginal stratification and cervico-vaginal tumors later in life. These effects are due to altered cell fate following DES exposure during a critical developmental period. The detailed mechanisms underlying the reversible and irreversible cell proliferation in vaginae induced by DES at different ages has not been clarified. Therefore, we examined differences in gene expression pattern using DNA microarray analysis in mouse vaginae 6 hrs after a single injection of 2 mug DES per gram of body weight, and proliferation of vaginal epithelial and stromal cells 24 hrs after the injection at postnatal days (PNDs) 0, 5, 20, and 70. After DES stimulation, vaginal epithelial and stromal cells showed cell proliferation at PNDs 20 and 70, and at PNDs 0 and 5, respectively. DNA microarray analysis exhibited 54 DES-induced genes and 9 DES-repressed genes in vaginae at PND 0, whereas more than 200 DES-induced genes were found in vaginae at PNDs 5 and 20, and 350 genes at PND 70. Clustering analysis of DES-induced genes in the vaginae at different ages revealed that genes induced by DES at PND 5 were closer to the adult type than that of PND 0. Genes related to keratinocyte differentiation, such as Gadd45alpha, p21, 14-3-3 sigma, small proline-rich protein 2f (Sprr2f), and Krupple-like factor 4 (Klf4), were induced by DES. The number of DES-induced genes during the critical period, PND 0, was smaller than those found after the critical period. These results give insight toward understanding the molecular mechanisms underlying the critical period in mouse vaginae.

Animals↗

PubMed2006

Fas ligand mRNA levels of circulating leukocytes reflect endothelial dysfunction in hyperlipidemic but not in non-hyperlipidemic patients.

To find a novel marker for identifying patients at high-risk for endothelial dysfunction among patients with atherosclerosis, we examined the correlation between mRNA levels of Fas ligand (FasL), an apoptosis-inducing factor, in circulating leukocytes and clinical parameters in these patients. FasL mRNA levels of circulating leukocytes were measured with the TaqMan-PCR method. A negative correlation was observed between brachial artery flow-mediated dilatation (%FMD) and FasL mRNA levels of leukocytes in hyperlipidemic but not in non-hyperlipidemic patients. %FMD was more impaired in patients with a high level of FasL mRNA than in those with a low level of FasL mRNA. Interestingly, the improvement of %FMD by treatment with a 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor (simvastatin) was greater in the group showing a decrease in FasL mRNA than in the group with no such decrease. Additionally, simvastatin suppressed the FasL mRNA expression in leukocytes and decreased plasma oxidized low-density lipoprotein (OxLDL) levels. Furthermore, the supernatant of cultured leukocytes from hyperlipidemic patients induced cell death in Jurkat T cells, which was neutralized by an antibody against FasL. These findings suggest that high FasL mRNA expression in circulating leukocytes may be a marker of high-risk for endothelial dysfunction in hyperlipidemic but not in non-hyperlipidemic patients. This information may provide a novel basis for targeting of statin therapy in patients with vulnerable plaques.

Aged↗

PubMed2005

Cerebral regional cortical blood flow response during joint stimulation in cats.

Noxious stimulation of an elbow joint in the anesthetized cat increases cerebral blood flow over broad, bilateral areas of the cerebral cortex and increases systemic blood pressure. In order to eliminate the confounding effects of elevated blood pressure on cerebral blood flow, we re-examined this phenomenon in cats with a transected spinal cord at the T1 level. Noxious stimulation of an elbow joint resulted in a significant increase in blood flow in the forelimb area of the contralateral primary somatosensory cortex; the blood pressure remained unchanged. These data in cats suggest that the previously described bilateral increase in cerebral blood flow following noxious joint stimulation was due, in part, to the increased blood pressure.

Animals↗

PubMed2004

Childhood-onset schizophrenia and tryptophan hydroxylase gene polymorphism.

We explored the relationship between the tryptophan hydroxylase gene polymorphism and susceptibility to childhood-onset schizophrenia in a Japanese sample. Subjects were 51 Japanese patients who met DSM-IV criteria for schizophrenia before age 16 and 148 Japanese healthy controls. DNA was extracted from whole blood and genotyping was performed by PCR-RFLP using Nhe I. The frequency of the A allele was relatively higher in patients with childhood-onset schizophrenia than in controls (odds ratio, OR = 1.47, 95% CI = 0.97-2.37, P = 0.097). There was a nearly doubling of the risk for childhood-onset schizophrenia associated with the AA genotype compared to other genotype groups; OR = 1.97, 95% CI = 0.91-4.22, P = 0.058.

Adolescent↗

PubMed2004

Enhanced iNOS expression in leukocytes and circulating endothelial cells is associated with the progression of coronary artery lesions in acute Kawasaki disease.

Nitric oxide (NO) serves many vasoprotective roles, but the massive release of NO causes arterial wall degeneration. We investigated whether enhanced nitric oxide synthase (iNOS) expression in peripheral blood leukocytes and circulating endothelial cells mirrors the progression of coronary arterial lesions in 55 children with acute Kawasaki disease (KD), including 24 with and 31 without coronary artery lesions (CAL). Patients were treated with i.v. gamma-globulin at the time of diagnosis and blood samples were collected before and after treatment. The cellular origin of NO synthesis was determined by flow cytometric analysis of iNOS expression in peripheral blood, and by immunohistochemical analysis of circulating endothelial cells and coronary arteries. iNOS expression in neutrophils peaked at the time of diagnosis, but did not peak in monocytes until 2 wk post onset of disease. Levels were significantly higher in both cell types in patients with CAL (p = 0.001 and p = 0.035, respectively). In addition, the number of circulating endothelial cells and levels of iNOS expression were higher in patients with CAL (p = 0.011 and p = 0.012, respectively). Immunohistochemical analysis of the coronary arteries from three patients with acute KD revealed iNOS immunoreactivity in endothelial cells, as well as infiltrating monocytes/macrophages in the aneurysms. We conclude that the expression of iNOS in peripheral blood leukocytes, as well as circulating endothelial cells, correlates with the severity of coronary arterial wall injury and the progression of CAL in patients with acute KD.

Arteries↗

PubMed2004

Immunohistochemical study of apparently intact coronary artery in a child after Kawasaki disease.

BACKGROUND: Coronary arterial lesions (CAL) due to Kawasaki disease (KD) often show progressive intimal hyperplasia even many years after the disease. However, most patients have no CAL after the acute phase, and it is an important issue whether or not coronary arteries without CAL have significant intimal hyperplasia, and whether or not there is the potential for this to progress to stenosis and/or atherosclerosis. METHODS: The authors examined formalin-fixed specimens of the coronary arteries immunohistochemically, using antibodies against vascular growth factors (GFs), the receptors of transforming growth factor-beta (TbetaRs) and inducible nitric oxid synthesis (iNOS) in a KD patient without CAL, and also in four control patients: two with CAL due to KD and two without a history of KD. RESULTS: Vascular endothelial GFs, Platelet-derived growth factor-A (PDGF-A) and TbetaRs were expressed in the vascular smooth muscle cells of all patients. PDGF-A, transforming Gfbeta1 and iNOS were expressed in the intimal smooth muscle cells of the KD but not the normal coronary artery without a history of KD. The number of TbetaR-II-positive cells were fewer than TbetaR-I-positive cells in the intima of CAL due to KD, but the number was of both almost same in the intima of coronary artery without CAL after KD and in the normal coronary. CONCLUSION: The intact coronary artery 13 months after KD still showed the influence of the inflammation of KD. Although the authors speculate that the intimal proliferation will not continue beyond the acute phase, those patients may have a risk factor for atherosclerosis.

Child, Preschool↗

PubMed2004

Development of an experimental system for evaluation of stress effect on ethyl alcohol metabolism using radiorespirometric analysis in rat.

We attempted to develop an experimental system for evaluation of stress effect on ethyl alcohol metabolism by the radiorespirometric analysis using [(14)C]ethyl alcohol. Each rat was immobilized in an adjustable restraint device for 3 h. The excretion of (14)CO(2) in the breath was significantly decreased by restraint stress. The liver alcohol dehydrogenase activity was also decreased by restraint stress. We think that radiorespirometric analysis may be useful for the evaluation of stress effect on real metabolism of ethyl alcohol in the liver.

Alcohol Dehydrogenase↗

PubMed2004

Recovery of action potentials and twitches after K-contractures in frog skeletal muscle.

To give information about intracellular Ca2+ translocation during and after K-contractures in vertebrate skeletal muscle fibers, we examined recovery of action potentials and twitches after interruption and spontaneous relaxation of K-contractures at low temperature (3 degrees C) that greatly reduced the rate of Ca2+ reuptake by the sarcoplasmic reticulum. On membrane repolarization interrupting K-contractures, the amplitude of both action potentials and twitches recovered quickly, while the falling phase of action potential was markedly slowed at first to prolong its refractory period, so that repetitive stimulation (20 Hz) did not produce a complete tetanus. Meanwhile, on membrane repolarization after spontaneous relaxation of K-contractures, the action potentials were markedly reduced in amplitude and prolonged in duration at first, also resulting in prolonged refractory period. These results are discussed in connection with Ca2+ absorption to the surface and transverse tubule membranes, producing changes in action potential kinetics.

Action Potentials↗

PubMed2004

The effects of aging on somatocardiac reflexes in anesthetized rats.

Nociceptive cutaneous stimulation produces a reflex tachycardiac response that is mediated through the activation of cardiac sympathetic efferents. This response includes reflex components of both supraspinal and spinal origin, depending on which segmental afferent area is stimulated (for a review see Sato et al.: Rev Physiol Biochem Pharmacol 130: 1-328, 1997). We herein examined the effects of aging on these supraspinal and spinal reflexes in anesthetized rats that were 4-7 (young adult), 24-27 (old), and 32-36 (very old) months of age. In central nervous system (CNS)-intact animals, we found that the supraspinal tachycardiac response induced by the pinching of a hindpaw was well preserved in old rats but was significantly attenuated in very old rats, while pinching-induced increases in cardiac sympathetic nerve activity were well maintained in both of these rat populations. In spinalized animals, spinal-mediated changes in heart rate (HR) and cardiac sympathetic nerve activity induced by the pinching of the chest skin were well preserved in both old and very old rats. There were no significant differences in resting HR among the 3 age groups studied, though the maximum HR induced by the beta-adrenergic agonist isoproterenol was reduced with age. The beta-receptor-mediated maximum HR was greater than that induced by pinching in young adult and old rats, CNS-intact and spinalized rats, and very old spinalized rats, while the maximum HR was nearly the same as the pinching-induced HR in CNS-intact very old rats. These results suggest that both supraspinal and spinal neural reflex pathways involved in the cardiac sympathetic response to cutaneous pinching are well preserved in older animals. They also suggest that the decline in the responsiveness of the heart to beta-adrenergic stimulation results in a reduced pinching-induced supraspinal tachycardiac response in very old rats.

Aging↗

PubMed2004

[Review of the gender research in cross-cultural psychology since 1990: conceptual definitions and methodology].

A review of the cross-cultural research on gender in psychology since 1990 reveals (1) conceptual confusion of the definitions of sex, gender, man, and woman; (2) diversification, refinement, reification, and a problem-solving orientation in the research topics; and (3) the possibility of the elucidation of the psychological sex-difference mechanism in relation to the biological sex differences. A comparison of 1990 and 2000 cross-cultural psychological articles published in "Sex Roles" found that overall, the research is Western-centered and some methodological problems remain to be solved concerning the measures and the sampling. These findings lead to the following suggestions for cross-cultural research on gender to resolve the problems and contribute to the development of psychology in general: (1) use of an operational definition for conceptual equivalence; (2) conducting more etic-approach research; (3) avoiding ethnocentric or androcentric research attitudes; (4) use of a theoretical framework; (5) strict examination of methodologies; and (6) examination of the specific context of participants in terms of cultural diversity, dynamics of husband-wife relationships, and relationships with husbands and fathers.

Cross-Cultural Comparison↗

PubMed2003

The effect of walking on regional blood flow and acetylcholine in the hippocampus in conscious rats.

Recent studies in our laboratory have demonstrated that stimulation of the septal complex (i.e., the medial septal nucleus and the nucleus of the diagonal band) increases extracellular acetylcholine (ACh) release and, consequently, results in an increase in regional cerebral blood flow in the hippocampus (Hpc CBF) via activation of the nicotinic ACh receptors (nAChRs) [Neurosci. Lett. 107 (1989) 135; Neurosci. Lett. 112 (1990a) 263]. The present study aimed to examine the effects of walking on Hpc CBF, measured by laser Doppler flowmetry, in conscious rats. Walking at a moderate speed (4 cm/s) on a treadmill for 30 s produced increases in Hpc CBF and mean arterial pressure (MAP), reaching 107 +/- 1% and 105 +/- 1% of the prewalking control values, respectively. Walking for 3 min produced an increase in ACh release in the extracellular space of the hippocampus. The increase in Hpc CBF during walking was attenuated by mecamylamine (abbreviated as MEC here; 2 mg/kg, i.v.), a nAChR antagonist permeable to the blood-brain barrier (BBB), but not by hexamethonium (denoted as C6 here; 20 mg/kg, i.v.), a nAChR antagonist impermeable to the BBB, while the walking-induced increase in MAP was abolished by either agent. The response of Hpc CBF and MAP were not altered by atropine (abbreviated as ATR here; 0.5 mg/kg, i.v.), a muscarinic AChR antagonist permeable to the BBB. The increase in Hpc CBF during walking was attenuated by N(omega)-nitro-L-arginine methyl ester (L-NAME, 3 and 30 mg/kg, i.v.), a nitric oxide synthase (NOS) inhibitor, and the reduced responses were reversed following the intravenous (i.v.) administration of a physiological precursor of NO, L-arginine (600 mg/kg). The results suggest that the increase in Hpc CBF during walking is independent of MAP and attributable at least to activation of the nAChRs by the cholinergic vasodilator nerves projecting to the hippocampus and to production of NO in the hippocampus.

Acetylcholine↗

PubMed2003

Effect of moxibustion stimulation of various skin areas on cortical cerebral blood flow in anesthetized rats.

The effect of moxibustion stimulation of various skin areas (cheek, forepaw, upper arm, chest, back, lower leg, hindpaw and perineum) on cerebral blood flow (CBF) of the parietal cortex was examined in anesthetized rats after eliminating emotional influences. Moxibustion stimulation was performed by burning a moxa cone of about 4 mg weight placed on the shaved skin. CBF of the parietal cortex was measured using a laser Doppler flowmeter. Stimulation of the cheek, forepaw, upper arm and hindpaw produced significant increases in CBF, but stimulation of the other areas did not produce significant responses. Moxibustion stimulation of the forepaw and hindpaw produced an increase in the mean arterial pressure (MAP), while stimulation of the other areas did not. After spinal transection at the 2nd thoracic level, the MAP response to stimulation of the forepaw was abolished, whereas the CBF response to stimulation of the forepaw remained. The CBF response in spinalized rats was not affected by cutting cervical sympathetic and facial parasympathetic nerves, while it was almost abolished by intravenous administration of muscarinic and nicotinic cholinergic blocking agents. The CBF response was abolished by crushing the brachial plexus ipsilateral to the stimulated side. It is suggested that the increase in CBF, independent of MAP and emotional responses, elicited by moxibustion stimulation is a reflex response whose afferent pathway is composed of somatic afferent nerves, and whose efferent pathway involves intracerebral cholinergic nerves. A contribution of endogenous opioids in the present CBF responses was neglected, because naloxone did not influence the CBF responses.

Animals↗