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Biomedical subjects

Kentaro Hayashi

Publications and source records attributed to Kentaro Hayashi.

At least 19 recordsLinked to original sources
PubMed2007

Loss of control over eating reflects eating disturbances and general psychopathology.

This study examined the clinical significance of the loss of control over eating as a key component of eating disorders. It investigated the association of eating-related psychopathology and general psychopathology with objective bulimic episodes (OBEs; experiencing a loss of control while consuming large amounts of food) and subjective bulimic episodes (SBEs; experiencing a loss of control while consuming small/moderate amounts). A community sample of 81 women with a range of disordered eating was recruited: binge-eating disorder, bulimia nervosa, subclinical eating disturbances, or no eating disorders. They were interviewed using the Eating Disorder Examination and completed measures of eating-related and general psychopathology. Both OBE and SBE frequencies correlated significantly with measures of eating-related and general psychopathology, and no significant differences were found between the magnitudes of the correlations with either binge episode type. SBE frequency significantly and independently predicted global eating disorder psychopathology. The loss of control over eating, without consuming large amounts of food, was as closely associated with specific eating disorder psychopathology and general mental health as were traditionally defined OBEs. SBEs may be an important target of treatment and should be considered for future diagnostic classifications of eating disorders.

Adolescent↗
PubMed2006

Adrenomedullin improves the blood-brain barrier function through the expression of claudin-5.

AIMS: Brain vascular endothelial cells secret Adrenomedullin (AM) has multifunctional biological properties. AM affects cerebral blood flow and blood-brain barrier (BBB) function. We studied the role of AM on the permeability and tight junction proteins of brain microvascular endothelial cells (BMEC). METHODS: BMEC were isolated from rats and a BBB in vitro model was generated. The barrier functions were studied by measuring the transendothelial electrical resistance (TEER) and the permeability of sodium fluorescein and Evans' blue albumin. The expressions of tight junction proteins were analyzed using immunocytochemistry and immunoblotting. RESULTS: AM increased TEER of BMEC monolayer dose-dependently. Immunocytochemistry revealed that AM enhanced the claudin-5 expression at a cell-cell contact site in a dose-dependent manner. Immunoblotting also showed an overexpression of claudin-5 in AM exposure. CONCLUSIONS: AM therefore inhibits the paracellular transport in a BBB in vitro model through claudin-5 overexpression.

Adrenomedullin↗
PubMed2006

Change of the persistence lengths in the conformational transitions of pullulan- and amylose-tricarbanilates.

With raising temperature in the domain of 20 to 60 degrees C, the intrinsic viscosity [eta] for pullulan-tricarbanilate PTC and amylose-tricarbanilate ATC in solutions was found to decrease, indicating that they exhibited thermal-induced conformational transition from expanded form to compact form. The persistence length P(l) of the chains, evaluated with small-angle X-ray scattering, has also decreased as the temperature is raised and, moreover, it significantly depended on the solvents employed, where as P(l) of pullulan, having no carbanilate groups, has exhibited neither temperature- nor solvent-dependence. The temperature dependence of [eta] for PTC and ATC was well elucidated in terms of the temperature-dependent P(l) with the wormlike chain model. From these results, it is suggested that intramolecular hydrogen bonds would be formed between carbanilate groups neighboring along the backbone chain, but they are gradually and cooperatively collapsed as the temperature is raised, inducing the conformational transition.

Amylose↗
PubMed2006

Bacillus subtilis RghR (YvaN) represses rapG and rapH, which encode inhibitors of expression of the srfA operon.

Rap proteins regulate the activity of response regulators including Spo0F, DegU and ComA. We found that overexpression of either RapG or RapH severely downregulated the expression of srfA, which belongs to the ComA regulon. Disruption of those genes, however, showed small effects on srfA expression. These observations suggested that Bacillus subtilis cells possess a repressor for rapG and rapH. To identify candidate repressors we developed a novel transcription factor array (TF array) assay, in which disruptions of 287 genes encoding regulatory proteins were independently transformed into a strain carrying rapH-lacZ and the resultant transformants were grown on agar plates containing Xgal to detect beta-galactosidase activity. We identified a yvaN disruptant which showed a rapH-overproducing phenotype. DNA microarray analysis of the yvaN mutant suggested that both rapG and rapH were overproduced, leading to inhibition of srfA expression. In a gel retardation assay, purified His-tagged YvaN specifically bound to promoter sequences of rapG and rapH. Further footprint and gel retardation analyses using various deleted probes uncovered critical sequences for YvaN binding. In addition, a lacZ fusion analysis confirmed the significance of YvaN binding for transcription regulation of rapG and rapH. Thus, YvaN was renamed RghR (rapG and rapH repressor). As the rapH gene is activated by ComK and RapH inhibits comK indirectly, this constitutes an autoregulatory loop modulated by RghR.

Bacillus subtilis↗
PubMed2006

Standard errors in covariance structure models: asymptotics versus bootstrap.

Commonly used formulae for standard error (SE) estimates in covariance structure analysis are derived under the assumption of a correctly specified model. In practice, a model is at best only an approximation to the real world. It is important to know whether the estimates of SEs as provided by standard software are consistent when a model is misspecified, and to understand why if not. Bootstrap procedures provide nonparametric estimates of SEs that automatically account for distribution violation. It is also necessary to know whether bootstrap estimates of SEs are consistent. This paper studies the relationship between the bootstrap estimates of SEs and those based on asymptotics. Examples are used to illustrate various versions of asymptotic variance-covariance matrices and their validity. Conditions for the consistency of the bootstrap estimates of SEs are identified and discussed. Numerical examples are provided to illustrate the relationship of different estimates of SEs and covariance matrices.

Adolescent↗
PubMed2006

[A case of a vertebral artery fusiform aneurysm treated with stent assisted coil embolization: technique to prevent coil migration].

Placement of a stent over the aneurysm neck and secondary coil embolization prevents coil migration and allows attenuated packing of the coils. However, during the course of the embolization, coils project over and obscure the parent vessel. Here we report a novel technique for endovascular parent vessel reconstruction with aneurysm embolization. A 73-year-old male had an incidental fusiform aneurysm at the V4 segment of the left vertebral artery. The size of the aneurysm increased from 7 mm to 8 mm in diameter. Since the right vertebral artery was hypoplastic, endovascular parent vessel reconstruction with coil embolization was performed. A flexible balloon-expandable coronary stent was navigated to the lesion and deployed successfully followed by coil embolization using a microcatheter through the stent. The balloon was inflated intermittently during coil insertion avoiding coil migration to inside the stent. Furthermore, the angle of the image intensifier was manipulated to visualize the inside of the stent. Postoperative course was uneventful and follow-up MRI three moths later demonstrated obliteration of the aneurysm and patency of the parent artery. This technique provides a practical treatment strategy for the management of a circumferential aneurysm.

Aged↗
PubMed2006

[A case of carotid occlusive disease treated with stenting for recurrence of stenosis: strategy on intolerance to temporary occlusion].

Carotid artery stenting has emerged as an acceptable treatment alternative in patient with occlusive carotid bifurcation disease. High-risk surgical candidates have a lower rate of morbidity after carotid artery stenting with distal embolic protection. Among distal protection devices, a Guardwire balloon occlusion is the most frequently employed in Japan. A 79-year-old male who had severe stenosis at the origin of left carotid artery was treated with stenting under Guardwire balloon protection. He was intolerant to carotid artery occlusion and endovascular procedures were performed under intravenous anesthesia or general anesthesia. In addition, he suffered recurrent stenosis seven months after the first procedure and 16 months after second procedure, and underwent repeated intervention. It was considered that the long tortuous lesion was a cause of the recurrent stenosis.

Aged↗
PubMed2005

HIV-TAT protein upregulates expression of multidrug resistance protein 1 in the blood-brain barrier.

Central nervous system (CNS) complications of human immunodeficiency virus (HIV) infection remain a serious health risk in HIV/acquired immunodeficiency syndrome despite significant advances in highly active antiretroviral therapy (HAART). Specific drugs used for HAART are substrates for the efflux transport systems, such as the multidrug resistance-associated proteins (MRPs), which are present on brain microvascular endothelial cells (BMEC) and astrocytes, that is, the main cell types that form the blood-brain barrier (BBB). Thus, drugs employed in HAART are actively removed from the CNS and do not efficiently inhibit HIV replication in the brain. To study the potential mechanisms of this process, the aim of the present research was to address the hypothesis that HIV Tat protein can contribute to upregulation of MRP expression at the BBB level. Tat is a protein produced and released by HIV-infected cells, which may play an important role in brain vascular pathology in the course of HIV infection. Among the family of MRPs, exposure to Tat specifically induced MRP1 messenger ribonucleic acid and protein expression both in BMEC and astrocytes. These alterations were accompanied by enhanced MRP1-mediated efflux functions. Furthermore, activation of the mitogen-activated protein kinase signaling cascade was identified as the mechanism involved in Tat-mediated overexpression of MRP1. These results indicate that Tat exposure can lead to alterations of the BBB functions and decrease HAART efficacy in the CNS through overexpression of drug efflux transporters.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2005

Premorbid childhood ocular alignment abnormalities and adult schizophrenia-spectrum disorder.

This study examined the relation between childhood ocular alignment deficits and adult psychiatric outcomes among children at high-risk for schizophrenia and controls. A sample of 265 Danish children was administered a standardized eye exam assessing strabismus and related ocular alignment deficits. All children whose mothers or fathers had a psychiatric diagnosis of schizophrenia comprised the first group (N=90). Children who had at least one parent with a diagnosis other than schizophrenia comprised the first matched control group (N=93). The second control group consisted of children with no parental diagnoses (N=82). In 1992, adult psychiatric outcome data were obtained for 242 of the original subjects. It was found that children who later developed a schizophrenia-spectrum disorder had significantly higher eye exam scale and strabismus scale scores compared to children who developed other non-psychotic psychopathology and children who did not develop a mental illness. The mean rank for children in the high-risk group (offspring of parents with schizophrenia) on the eye scale and the strabismus scale was greater than the mean rank for children in the matched control groups (both offspring of parents with other non-psychotic disorder and no mental illness), although the results failed to reach statistical significance. Results from this study suggest a premorbid relation between ocular deficits and schizophrenia-spectrum disorders in childhood prior to onset of psychopathology in adulthood. Strabismus may serve as a premorbid marker for spectrum disorders and may have implications for the understanding of early aberrant neurological development related to later schizophrenia-spectrum disorders.

Adult↗
PubMed2005

HIV-1 Tat protein-induced alterations of ZO-1 expression are mediated by redox-regulated ERK 1/2 activation.

HIV-1 Tat protein plays an important role in inducing monocyte infiltration into the brain and may alter the structure and functions of the blood-brain barrier (BBB). The BBB serves as a frontline defense system, protecting the central nervous system from infected monocytes entering the brain. Therefore, the aim of the present study was to examine the mechanisms of Tat effect on the integrity of the BBB in the mouse brain. Tat was injected into the right hippocampi of C57BL/6 mice and expression of tight junction protein zonula occludens-1 (ZO-1) was determined in control and treated mice. Tat administration resulted in decreased mRNA levels of ZO-1 and marked disruption of ZO-1 continuity. These changes were associated with accumulation of inflammatory cells in brain tissue of Tat-treated mice. Further experiments indicated that Tat-mediated alterations of redox-related signaling may be responsible for decreased ZO-1 expression. Specifically, injections with Tat resulted in activation of extracellular signal-regulated kinase 1/2 (ERK 1/2) and pretreatment with U 0126, a specific inhibitor of ERK kinase, effectively ameliorated the Tat-induced diminished ZO-1 levels. In addition, administration of N-acetylcysteine (NAC), a precursor of glutathione and a potent antioxidant, attenuated both Tat-induced ERK 1/2 activation and alterations in ZO-1 expression. These results indicate that Tat-induced oxidative stress can play an important role in affecting the integrity of the BBB through the ERK 1/2 pathway.

Animals↗
PubMed2005

HIV-Tat protein induces P-glycoprotein expression in brain microvascular endothelial cells.

Among the different factors which can contribute to CNS alterations associated with HIV infection, Tat protein is considered to play a critical role. Evidence indicates that Tat can contribute to brain vascular pathology through induction of endothelial cell activation. In the present study, we hypothesized that Tat can affect expression of P-glycoprotein (P-gp) in brain microvascular endothelial cells (BMEC). P-gp is an ATP-dependent cellular efflux transporter which is involved in the removal of specific non-polar molecules, including drugs used for highly active antiretroviral therapy (HAART). Treatment of BMEC with Tat(1-72) resulted in P-gp overexpression both at mRNA and protein levels. These alterations were confirmed in vivo in brain vessels of mice injected with Tat(1-72) into the hippocampus. Furthermore, pre-treatment of BMEC with SN50, a specific NF-kappaB inhibitor, protected against Tat(1-72)-stimulated expression of mdr1a gene, i.e. the gene which encodes for P-gp in rodents. Tat(1-72)-mediated changes in P-gp expression were correlated with increased rhodamine 123 efflux, indicating the up-regulation of transporter functions of P-gp. These results suggest that Tat-induced overexpression of P-gp in brain microvessels may have significant implications for the development of resistance to HAART and may be a contributing factor for low efficacy of HAART in the CNS.

ATP Binding Cassette Transporter, Subfamily B↗
PubMed2005

The H2O2 stress-responsive regulator PerR positively regulates srfA expression in Bacillus subtilis.

srfA is an operon required for the synthesis of surfactin and the development of genetic competence in Bacillus subtilis. We observed that the expression of srfA is downregulated upon treatment with H2O2. Thus, we examined the involvement of several oxidative stress-responsive transcription factors in srfA expression. Our DNA microarray analysis revealed that the H2O2 stress-responsive regulator PerR is required for srfA expression. This was confirmed by lacZ fusion analysis. A ComX feeding assay and epistatic analyses revealed that the role of PerR in srfA expression is independent of other known regulators of srfA expression, namely, comQXP, rapC, and spx. Gel mobility shift and footprint assays revealed that PerR binds directly to two tandemly arranged noncanonical PerR boxes located in the upstream promoter region of srfA. A transcriptional srfA-lacZ fusion lacking both PerR boxes showed diminished and PerR-independent expression, indicating that the PerR boxes we identified function as positive cis elements for srfA transcription.

Bacillus subtilis↗
PubMed2005

Observing the carotid debris aspirated during carotid stenting: technical note.

OBJECTIVES: Elective carotid stent implantation using a distal protection is increasing. In this article we describe an observation method for carotid plaque debris collection during carotid stenting. METHODS: Endovascular stenting for the right internal carotid artery (ICA) stenosis was performed under distal balloon protection. During balloon protection, 30 ml of blood containing debris was aspirated followed by vigorous saline irrigation flushing any residual debris out into the ipsilateral external carotid circulation. Post-operatively, the aspirated blood was filtered and the debris remained on the membrane. The membrane was stained with hematoxylin-eosin (HE) solution and then mounted onto a glass slide for visualization. RESULTS: Microscopic observation of the slide revealed several debris such as atheromatous plaques and intimal strips. HE staining facilitates the characterization of the debris composition. In addition to the histological evaluation, this technique revealed the particle size as well as the quantity of debris. The resulting HE slide is also suitable for permanent storage. In addition to the qualitative and quantitative qualities, this simple technique requires neither specific instrumentation nor equipment. DISCUSSION: Carotid plaque debris aspirated during carotid artery stenting under distal protection can be filtered and visualized on a permanent glass slide. This simple method allows us to better understand quantity, particle size, and composition of debris.

Aged↗
PubMed2004

Effects of hypoxia on endothelial/pericytic co-culture model of the blood-brain barrier.

The blood-brain barrier (BBB) is composed of endothelial cells, pericytes and astrocytic foot processes. Most research for the in vitro BBB is performed endothelial cells with or without astrocytes. Hypoxia damage to the BBB induces vasogenic brain edema. We have generated a new model of the BBB with brain endothelial cells and pericytes and have examined the effects of hypoxia using this model. Brain microvascular endothelial cells and pericytes were isolated from three-week-old male Wister rats using enzyme and mechanical homogenization. Three models (A: only endothelial monolayer, B: endothelial monolayer with pericytes non-contact condition, and C: contact condition) were made by culturing these cells using Transwell co-culture system and were exposed to hypoxic condition. We evaluated barrier function with transendothelial electrical resistance (TEER) and permeability of Evans blue-albumin and sodium fluorescein. The tightest barrier was observed in the endothelial/pericytic contact model. Despite hypoxia-induced disruption of the barrier in endothelial monolayer and non-contact co-culture models, a minimum of dysfunction was seen in the contact co-culture model. Therefore, it is considered that pericytes effect on the endothelia by secreting factors or through a gap junction. In short, pericytes induce endothelial maturation and a tighter barrier function, which supports the function against the hypoxic injury. Intercellular communication might be important to keep the BBB functional and stabilize in hypoxia.

Animals↗
PubMed2004

[Successful trans-arterial occlusion of a vertebral arteriovenous fistula with aid of intra vascular ultra sound (IVUS) and balloon catheter].

We report a case of spontaneous vertebral arteriovenous fistula manifesting pulsating tinnitus with left cervical bruit. A 50-year-old woman presented with pulsatile tinnitus of unknown duration. Angiography revealed a simple and direct fistula between the second segment of the left vertebral artery and the epidural venous system. The fistula was well visualized by intra vascular ultra sound (IVUS). Balloon catheters were used for regulating blood flow during coil embolization, which successfully obliterated the fistula, with subsequent control of the symptoms. Postoperative course (18 months) was uneventful.

Arteriovenous Fistula↗