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Biomedical subjects

Shinichi Nakamura

Publications and source records attributed to Shinichi Nakamura.

At least 19 recordsLinked to original sources
PubMed2006

A sensitive semi-micro column HPLC method with peroxyoxalate chemiluminescence detection and column switching for determination of MDMA-related compounds in hair.

A sensitive semi-micro column HPLC method with peroxyoxalate chemiluminescence (POCL) detection and column switching has been developed for simultaneous determination of 3,4-methylenedioxymethamphetamine (MDMA) and related compounds, for example 3,4-methylenedioxyamphetamine, methamphetamine, and amphetamine, in hair. After digestion of the hair with 1 mol L-1 sodium hydroxide the compounds were extracted with n-heptane and derivatized with 4-(N,N-dimethylaminosulfonyl)-7-fluoro-2,1,3-benzoxadiazole. A mixture of hydrogen peroxide and bis(2,4,5-trichloro-6-carbopentoxyphenyl)oxalate in acetonitrile was used as post-column CL reagent. Calibration plots showed linearity was good (r=0.999); detection limits were 0.02-0.16 ng mg-1 hair at a signal-to-noise ratio of 3. The precision of the method, as RSD (n=5), in intra-day and inter-day assays was better than 5.0 and 6.9%, respectively. The proposed method was sufficiently sensitive to detect low ng mg-1 levels of MDMA and related compounds in hair, and could be used for quantification of the compounds in hair samples from patients treated in a chemical dependency unit.

Calibration↗
PubMed2006

Perospirone in treatment of Huntington's disease: a first case report.

Huntington's disease (HD) is a hereditary disorder clinically characterized by involuntary movements, cognitive decline and psychiatric symptoms. We report on a patient with HD, whose involuntary movements and psychiatric symptoms were clinically improved with perospirone, a second-generation antipsychotic agent with antagonistic effects on serotonin 5-HT(2A) and dopamine D(2) (D(2)) receptors, as well as a unique agonistic effect on serotonin 5-HT(1A) (5-HT(1A)) receptors. The fact that perospirone antagonizes D(2) receptors could explain its effects on the hyperkinetic syndrome, while its agonistic effects on 5-HT(1A) receptors may explain the amelioration of psychiatric symptoms (fear and anxiety) in this patient. Future studies would be valuable to elucidate the utility of perospirone for the treatment of involuntary movements and psychiatric symptoms in HD.

Aged↗
PubMed2006

Disinfection of Legionella pneumophila by ultrasonic treatment with TiO2.

An ultrasonic treatment system, using a TiO2 photocatalyst, was used to disinfect Legionella pneumophila. A kinetic study of the process indicates that TiO2 significantly improves the disinfection process. The concentrations of viable cells were reduced to 6% of the initial concentrations in the presence of 0.2g/ml TiO2 after a 30 min of treatment period, while only an 18% reduction was observed in the absence of TiO2 . The potency of the disinfection could be enhanced, to some extent, by increasing the amount of TiO2 used. Cell concentrations were decreased by an order of 3 within 30 min of treatment in the presence of 1.0 g/ml TiO2 . The disinfection power in the presence of TiO2 versus Al2O3 was also compared and the findings showed that TiO2 induced a higher cell killing. No significant effect of initial cell concentration on the disinfection was found in the range of 10(2)-10(7) CFU/ml after a 30 min of treatment period. The mechanism of cell killing was investigated by examining the effects of OH radical scavengers such as ascorbic acid, histidine and glutathione. The disinfection power was reduced in samples that contained these radical scavengers, thus indicating the importance of OH radicals.

Aluminum Oxide↗
PubMed2005

Characterization of smooth muscle-like cells in circulating human peripheral blood.

Smooth muscle cells play an important role in human vascular diseases. Several lines of evidence demonstrate that circulating smooth muscle precursor cells contribute to intimal hyperplasia in animal models. We obtained large spindle cells expressing alpha-smooth muscle actin (alpha-SMA), denoted here as "smooth muscle-like cells" (SMLC), from human peripheral blood mononuclear cells (PBMC). SMLC derived from human PBMC proliferated readily and expressed pro-inflammatory genes during early culture. After long-term culture, SMLC could contract and express characteristic smooth muscle cell markers. We found peripheral blood mononuclear cell expressing alpha-smooth muscle actin in the circulating blood that bore CD14 and CD105. Sorted CD14/CD105 double-positive PBMC could differentiate into SMLC. The number of CD14-CD105-bearing PBMC increased significantly in patients with coronary artery disease compared to patients without coronary artery disease. These results support the novel concept that smooth muscle precursor cells exist in circulating human blood and may contribute to the pathogenesis of vascular diseases.

Actins↗
PubMed2005

Cytokine response of lymphocytes persistently infected with Chlamydia pneumoniae.

Chlamydia pneumoniae infection of lymphocytes in blood has been documented, and it is apparent that control of this pathogen in lymphocytes as well as immune functions of the infected lymphocytes may be critical in the development of chronic inflammatory diseases associated with infection by this bacterium. Since immune function of lymphocytes infected with C. pneumoniae has not been well studied, the cytokine response of lymphocytes infected with this pathogen was analyzed using an in vitro infection model of the Molt-4 human lymphoid cell line. C. pneumoniae infection of the cells showed a persistent infection without any vigorous growth of the bacteria. Analysis of the cytokine response of the cells persistently infected with C. pneumoniae showed minimum induction of inflammatory cytokine TNF-alpha message, determined by real-time reverse transcription (RT)-PCR in the lymphocytes, even though the infection of THP-1 monocytic cells showed a marked induction of this cytokine messages. BIC (a lymphocyte activation marker gene) as well as IFN-gamma messages were also minimally induced by the infection in Molt-4 lymphocytes. In contrast, constitutive expression of interleukin 8 (IL-8) messages of Molt-4 cells was suppressed by the infection. Thus, these results suggest that lymphocytes persistently infected with C. pneumoniae may have attenuated cytokine responses.

Chlamydia Infections↗
PubMed2005

Clostridium sardiniense Prévot 1938 and Clostridium absonum Nakamura et al. 1973 are heterotypic synonyms: evidence from phylogenetic analyses of phospholipase C and 16S rRNA sequences, and DNA relatedness.

Clostridium sardiniense Prévot 1938 and Clostridium absonum Nakamura et al. 1973 have long been considered similar in terms of their biological and biochemical properties, but their taxonomic positions have not been clarified by DNA-DNA hybridization studies or rigorous analysis of 16S rRNA genes. In the present study, DNA-DNA hybridization analysis revealed that C. absonum strains DSM 599(T), DSM 600 and KZ 1544 shared 83.0-86.3 % DNA relatedness with C. sardiniense DSM 2632(T). 16S rRNA gene sequence analysis showed that the C. absonum strains also shared high identity with C. sardiniense DSM 2632(T) (99.7, 99.3 and 99.8 % for DSM 599(T), DSM 600 and KZ 1544, respectively), implying that C. absonum and C. sardiniense are synonyms. In addition, alignment of the inferred amino acid sequences for phospholipase C (PLC) indicated 96.5 % identity between PLCs from C. sardiniense and C. absonum, but relatively low identity with other clostridial species. These results strongly suggest that the species C. sardiniense and C. absonum should be united, with the name C. sardiniense having priority.

Bacterial Proteins↗
PubMed2005

Colonization by Clostridium difficile of neonates in a hospital, and infants and children in three day-care facilities of Kanazawa, Japan.

The intestinal-carriage rates of Clostridium difficile in neonates hospitalized in the University Hospital's Center for Perinatal and Reproductive Health and in infants and children enrolled in two day-nurseries and a kindergarten were examined. Swab samples from the floors of these facilities were also analyzed to determine the extent of environmental contamination by this organism. C. difficile was found in the stool of only one of 40 neonates during the normal 1-week stay in the hospital after delivery. The isolate from the neonate was identical to that of her mother, as determined by PCR ribotyping, pulsed-field gel electrophoresis analysis, and toxin gene type, suggesting that the C. difficile-positive neonate acquired the organism from her mother rather than from the environment. By contrast, 47 (48.0%) of the 98 infants and children, comprising 50 enrolled in two day-nurseries who were >= 3 years old and 48 enrolled in a kindergarten who were 2-5 years old, carried C. difficile. The carriage rate in infants under 2 years of age was much higher (84.4%) than in children 2 years old and older (30.3%). When analyzed according to age group, the carriage rates were 100, 75.0, 45.5, 24.0, 38.5, and 23.5% in infants and children 0, 1, 2, 3, 4, and 5 years old, respectively. The observation that several children were colonized with the same type of C. difficile strain in each day-care facility, and that the floors of day-nursery A and kindergarten C were contaminated with C. difficile strains identical to those colonizing the intestines of children enrolled in those facilities suggests that cross-infection of C. difficile among children occurs through C. difficile-carrying children or their contaminated environments.

Carrier State↗
PubMed2004

14-3-3 proteins in Lewy body-like hyaline inclusions in patients with sporadic amyotrophic lateral sclerosis.

14-3-3 proteins are highly conserved eukaryotic proteins that regulate various types of signal transduction pathways through phosphorylation-dependent protein-protein interactions. 14-3-3 mRNAs have been shown to be up-regulated in the injured rat motor neurons and in the spinal cords of patients with amyotrophic lateral sclerosis (ALS). To investigate the role of 14-3-3 proteins in ALS, we performed immunohistochemical studies on 14-3-3 using autopsied spinal cords from patients with sporadic ALS (sALS) and non-ALS subjects without spinal cord involvement. In the anterior horn of both groups, strong 14-3-3 immunoreactivity was observed in the somata and proximal processes of motor neurons. Many spheroids from all of the sALS cases were also immunopositive for 14-3-3. In addition, Lewy body-like hyaline inclusions (LBHIs), which were present in some sALS cases, were intensely immunostained. Our findings suggest that even in the severely affected anterior horn of patients with sALS, remaining motor neurons may contain abundant 14-3-3 proteins, and that 14-3-3 proteins may be partly associated with the pathogenesis of sALS, in particular with the formation of LBHIs.

14-3-3 Proteins↗
PubMed2004

Prognostic value of remnant-like lipoprotein particle levels in patients with coronary artery disease and type II diabetes mellitus.

OBJECTIVES: This study prospectively examined whether the levels of high remnant-like lipoprotein particles (RLP) cholesterol have a significant risk and influence prognosis in patients with coronary artery disease (CAD) and type II diabetes mellitus (DM). BACKGROUND: Several studies have shown that triglyceride-rich lipoproteins contribute to atherosclerotic complications in type II DM. However, it remains to be established which triglyceride-rich lipoproteins contribute to this risk. METHODS: Levels of RLP cholesterol in fasting serum were measured by an immunoseparation method in 240 type II DM patients with (n = 120) or without (n = 120) CAD. The patients with CAD were followed up for a period of < or =24 months until the occurrence of one of the following clinical coronary events: re-admission or coronary revascularization due to recurrent or refractory angina pectoris, nonfatal myocardial infarction, or cardiac death. RESULTS: Patients with CAD had higher RLP levels than patients without CAD. Multivariate logistic regression analysis showed that high RLP cholesterol levels (>4.7 mg cholesterol/dl, representing the 75th percentile of the distribution of RLP cholesterol levels in control subjects) were a significant risk factor for the presence of CAD, independent of traditional risk factors. Kaplan-Meier analysis demonstrated that higher RLP cholesterol levels in patients with CAD resulted in a significantly higher probability for the development of coronary events. Multivariate Cox hazards analysis showed that high RLP cholesterol levels in patients with CAD were a significant predictor of future coronary events, independent of other risk factors. CONCLUSIONS: Increased levels of RLP cholesterol are a significant and independent risk factor of CAD and predict future coronary events in patients with CAD and type II DM.

Aged↗
PubMed2004

Hypochlorous acid, a macrophage product, induces endothelial apoptosis and tissue factor expression: involvement of myeloperoxidase-mediated oxidant in plaque erosion and thrombogenesis.

OBJECTIVE: Superficial erosion of coronary plaques due to endothelial loss causes acute coronary syndromes (ACS). Macrophages at erosive sites of human coronary atheroma present myeloperoxidase (MPO), an enzyme that produces hypochlorous acid (HOCl). METHODS AND RESULTS: Activated MPO-positive macrophages or exogenous HOCl promoted detachment of endothelial cells (EC) from "Matrigel" substrata in vitro. Pathophysiologically relevant concentrations of HOCl caused EC death in a concentration-dependent manner: HOCl (20 to 50 micromol/L) induced rapid shrinkage of EC with nuclear condensation and disruption of EC monolayers, whereas concentrations >100 micromol/L immediately induced blebbing of the EC plasma membrane without shrinkage. HOCl (30 to 50 micromol/L) also induced caspase-3 activation, poly (ADP-ribose) polymerase degradation, and DNA laddering in EC. HOCl rapidly decreased endothelial Bcl-2 and induced cytochrome-C release, indicating that HOCl activates apoptotic EC death, partially via mitochondrial damage. Increased intracellular glutathione (GSH) levels after treatment with GSH monoethyl ester (GSH-MEE) attenuated HOCl-induced EC apoptosis. Sublethal concentrations of HOCl (1.0 to 15 micromol/L) increased tissue factor in EC and GSH-MEE treatment limited this effect of HOCl. CONCLUSIONS: HOCl can provoke EC death and desquamation by either apoptotic or oncotic cell-death pathways, and sublethal concentrations of HOCl can increase endothelial tissue factor. These results show that MPO-positive macrophage-derived HOCl in the subendothelium of atheromata may participate in ACS by promoting superficial erosion and increasing thrombogenicity.

Antioxidants↗
PubMed2004

Echolucent carotid plaques predict future coronary events in patients with coronary artery disease.

OBJECTIVES: The purpose of this study was to examine whether echolucent carotid plaques predict future coronary events in patients with clinically stable coronary artery disease (CAD). BACKGROUND: Although rupture of coronary plaques is considered a major cause of acute coronary syndromes (ACS), the clinical estimation of coronary vulnerability still remains inconclusive. Ultrasound evaluation of carotid plaques with integrated backscatter (IBS) analysis can indicate the consistency/structure of the plaques. Lipid-rich lesions known as "unstable plaques" appear as echolucent plaques with low IBS values using this technique. METHODS: We investigated the echogenicity of carotid plaques using ultrasound with IBS in 286 consecutive CAD patients (71 with ACS and 215 with stable CAD). Coronary plaque complexity was also determined angiographically in stable CAD patients followed up for 30 months or until the occurrence of coronary events. RESULTS: The calibrated IBS values of carotid plaques in ACS patients were significantly lower than those in stable CAD patients (p < 0.01). Echolucent carotid plaques accurately predicted the existence of complex coronary plaques (predictive power of 83%). Kaplan-Meier analysis demonstrated a significantly higher probability of coronary events developing in patients with echolucent carotid plaques than in patients without this type of plaque (p < 0.001). The presence of echolucent carotid plaques in stable CAD patients predicted future coronary events independent of other risk factors (odds ratio 7.0, 95% confidence interval 2.3 to 21.4; p < 0.001). CONCLUSIONS: Echolucent carotid plaques with low IBS values predicted coronary plaque complexity and the development of future coronary complications in patients with stable CAD. Qualitative evaluation of carotid plaques using ultrasound with IBS is a clinically useful procedure for risk assessment of CAD patients.

Aged↗
PubMed2004

Essential involvement of IFN-gamma in Clostridium difficile toxin A-induced enteritis.

Clostridium difficile has emerged as the important causative agent of antibiotics-associated pseudomembranous colitis; especially its toxin A is presumed to be responsible for the colitis. We examined the pathophysiological roles of IFN-gamma in toxin A-induced enteritis using IFN-gamma knockout (KO) mice. When toxin A of C. difficile was injected into the ileal loops of BALB/c wild-type (WT) mice, massive fluid secretion, disruption of intestinal epithelial structure, and massive neutrophil infiltration developed within 4 h after the injection. IFN-gamma protein was faintly detected in some CD3-positive lymphocytes in the lamina propria and submucosa of the ileum of untreated WT mice. On the contrary, at 2 and 4 h after toxin A injection, IFN-gamma protein was detected in infiltrating neutrophils and to a lesser degree in CD3-positive lymphocytes. In the ileum of WT mice, toxin A treatment markedly enhanced the gene expression of TNF-alpha, macrophage inflammatory protein-1alpha and -2, KC, and ICAM-1 >2 h after treatment. In contrast, the histopathological changes were marginal, without enhanced fluid secretion in the ileum of toxin A-treated IFN-gamma KO mice. Moreover, toxin A-induced gene expression of TNF-alpha, neutrophil chemotactic chemokines, and ICMA-1 was remarkably attenuated in IFN-gamma KO mice. Furthermore, pretreatment of WT mice with a neutralizing anti-IFN-gamma Ab prevented toxin A-induced enteritis. These observations indicate that IFN-gamma is the crucial mediator of toxin A-induced acute enteritis and suggest that IFN-gamma is an important molecular target for the control of C. difficile-associated pseudomembranous colitis.

Animals↗
PubMed2004

Benzodiazepine-sensitive GABA(A) receptors in the commissural subnucleus of the NTS are involved in the carotid chemoreceptor reflex in rats.

We studied the role of benzodiazepine (BDZ) receptors in the commissural subnucleus of the nucleus tractus solitarius (commNTS) in chemoreceptor reflex in urethane-anesthetized, pancronium-immobilized, artificially ventilated and bilaterally vagotomized rats. A BDZ agonist, diazepam (1-4 micromol/kg), administered intravenously reduced resting phrenic nerve activity (PNA) and blood pressure (BP). Stimulation of carotid chemoreceptors induced an increase in PNA and an increase in BP. Diazepam inhibited this chemoreceptor reflex. The effects of intravenous injection of diazepam (4 micromol/kg) on the chemoreceptor reflex were antagonized by microinjection of the BDZ antagonist flumazenil (100 pmol) into the commNTS. Microinjection of flumazenil (100 pmol) alone had no effect on the basal PNA and BP, and the chemoreceptor reflex. These results suggest that BDZ receptors are present in the carotid chemoreceptor reflex pathway in the commNTS and potentiate GABA(A) transmission.

Animals↗
PubMed2004

Clostridium difficile colonization in healthy adults: transient colonization and correlation with enterococcal colonization.

The aim of the present study was to investigate the colonization status of Clostridium difficile in healthy individuals. In total, 139 healthy adults from two study groups were examined at intervals of 3 months. Among the 18 positive subjects, the number of subjects from whom C. difficile was isolated once, twice, three times or four times was 10 (55.6%), three (16.7%), two (11.1%) and three (16.7%), respectively. In the student group, different subjects were colonized by different PCR ribotype/PFGE types. However, the same PCR ribotype/PFGE types of C. difficile were isolated from different subjects in the employee group, indicating that cross-transmission may have occurred in this group. Continuous colonization by the same PCR ribotype/PFGE type was only observed in three subjects. C. difficile-positive subjects were significantly more densely colonized by enterococci (P<0.05) than C. difficile-negative subjects: subjects that were found to be C. difficile-positive three or four times appeared to have higher concentrations of enterococci. The present results demonstrate that, although colonization by a C. difficile strain is transient in many cases, there are healthy individuals that are colonized persistently by C. difficile. They also suggest that dense colonization of the intestine by enterococci may be associated with C. difficile colonization.

Adult↗
PubMed2004

[Effect of flumazenil on hypoglossal and phrenic nerves activities in rabbits].

BACKGROUND: Upper airway obstruction and inadequate ventilation often arise during sedation and anesthesia by benzodiazepines (Bz). Flumazenil antagonizes these effects of active benzodiazepines on the central nervous system. To estimate the influence of flumazenil on the endogenous Bz system related respiratory control, we studied the effect of flumazenil and diazepam on the neural activity and the respiratory response caused by a brief (60 sec) respiratory arrest (RA) manifested in the hypoglossal nerve (HG) and the phrenic nerve (PH) activities in rabbits. METHODS: Experiments were performed on adult rabbits which were vagotomized, paralyzed and artificially ventilated with 50% N2O, 50% oxygen and 0.5% sevoflurane. We evaluated and compared the effects of the sequential administrations of flumazenil and diazepam on the peak amplitude (AMP) as well as the root mean square (RMS) of HG and PH, and respiratory cycle (Tc). RESULTS: Flumazenil by itself increased HG activity more than PH activity with no influence on Tc. But it was not dose-related. Previous administration of flumazenil in total dose of 0.25 mg x kg(-1) could not prevent the anticipated respiratory depression caused by diazepam 2.0 mg x kg(-1). These depressions are greater in HG activity than in PH activity. Additional flumazenil 0.15 mg x kg(-1) following the administration of diazepam promptly reversed these inhibitory effects on HG activity beyond the control level. The same dose of flumazenil, however, did not reverse PH activity sufficiently. RA response was characterized by raised AMPs and augmented RMSs (deltaAMPs, deltaRMSs) with marked prolongation in Tc (deltaTc). Flumazenil and diazepam did not seem to have any influence upon these RA responses. There was a significant change in cardiovascular parameters with the tested dosages of flumazenil and diazepam, but the change was in the normal physiological range. CONCLUSIONS: These results suggest the possibility that the endogenous benzodiazepine system is likely to play an inhibitory role in the regulation of respiration, especially in the maintenance of upper airway patency but the system is unrelated to the chemosensitive-respiratory control.

Action Potentials↗
PubMed2004

[Propofol suppresses the responses in hypoglossal nerve activity to hypercapnic-hypoxic stimulation].

BACKGROUND: Upper airway obstruction and inadequate ventilation often arise during sedation and anesthesia by propofol. To estimate the influence of propofol (PP) on respiratory control, we studied its effect on the neural activity and the respiratory response caused by a brief (60 sec) respiratory arrest (RA) manifesting in the hypoglossal nerve (HG) and the phrenic nerve (PN) in rabbits. METHODS: Experiments were performed on adult rabbits vagotomized, paralyzed and ventilated artificially with 50% N2O, 50% oxygen and 0.5% sevoflurane. We evaluated and compared the effects of PP on the peak amplitude (AMP) and the root mean square (RMS) of HG and PH, and respiratory cycle (Tc). RESULTS: PP depressed HG activity more than PH activity, and increased Tc in a dose related manner, with 0.25 mg x kg(-1) x min(-1) continuous infusion, propofol soon began to reduce both AMPs without any remarkable changing in Tc. AMP&RMS-HG were reduced to about 35% and AMP&RMS-PN to 80% of control. Administration of propofol 1.5 mg x kg(-1) x min(-1) vanished the activity of HG in all animals. RA made a mixed hypercapnic and hypoxic condition and induced RA response which was characterized by raised AMPs, augmented RMSs (deltaAMPs, deltaRMSs) in activity of both nerves activity and lengthened Tc (deltaTc). PP depressed RA response in HG dose-dependently, but did not do so in PN. Significant depressions in cardiovascular effects with tested dosage of PP occurred, but the values were kept in physiological ranges. CONCLUSIONS: These results suggest that propofol induces respiratory depression by its inhibitory effect on the neural regulation of respiration, especially on the maintenance system of upper airway patency and the reflex related to the chemosensitive upper airway patency control.

Anesthetics, Intravenous↗