Biomedical subjects

S Hayashi

Publications and source records attributed to S Hayashi.

At least 91 records · Page 5Linked to original sources

PubMed2001

Analysis of transient expression of estrogen receptor-alpha in newborn rat primary auditory cortex.

In the primary temporal cortex (Te1) of newborn rats, we detected transient expression of alpha-type estrogen receptor (ER alpha). Since they have a pyramidal-like shape, they are considered neurons. By immunohistochemistry we found that they were absolutely devoid of glial fibrillary acidic protein but some of them contained calretinin, a calcium binding protein. It is already known that neurons in layer V of the Te1 extend their projections to the contralateral side of the Te1, the ipsilateral inferior colliculus, or the ipsilateral medial geniculate nucleus. Thus, we applied a retrograde track tracer into those regions of newborn rats and examined the possible colocalization of ER alpha signals and the tracer in the same cells. So far no clear colocalization of both signals has been detected in cells in the Te1. Thus, the cells expressing ER alpha transiently are not projecting to the assumed regions, at least at the newborn age examined in the present experiment. The possibility exists that (1) they are not projection neurons but local interneurons, (2) even though they are projection neurons, they did not have any synaptic contacts with their target region(s), (3) they may die after they are attached to the target neurons. Further analyses are needed to clarify the biological roles of ER alpha expressed transiently in these neurons. On the other hand, no ER beta cells were detected in the same region of the brain under the same condition. Thus, this finding was limited to the ER alpha.

Animals↗

PubMed2001

Inhibition of neointimal formation after balloon injury by cilostazol, accompanied by improvement of endothelial dysfunction and induction of hepatocyte growth factor in rat diabetes model.

AIMS/HYPOTHESIS: Cilostazol, a well-known phosphodiesterase type 3 (PDE3) inhibitor for the treatment of peripheral arterial disease, has vasodilator properties and an anti-proliferative action on the growth of vascular smooth muscle cells. In this study, we tested whether cilostazol inhibits neointimal formation and improves endothelial dysfunction after balloon injury in non-diabetic and diabetic rats. METHODS: Cilostazol or vehicle was administered to non-diabetic and streptozotocin-induced diabetic rats from 7 days before to 14 days after balloon injury of the carotid artery. We focused on the expression of hepatocyte growth factor to explore how cilostazol improved endothelial dysfunction. Also, we studied the effects of cilostazol on hepatocyte growth factor production in in vitro experiments. RESULTS: At 14 days after injury, the ratio of neointimal to medial area was decreased in rats treated with cilostazol in non-diabetic and diabetic animals. The impaired response to acetylcholine in balloon injured vessels was improved by cilostazol in non-diabetic and diabetic rats (p < 0.05). Vascular hepatocyte growth factor concentration was decreased in injured vessels of non-diabetic rats compared to uninjured vessels. Moreover, hepatocyte growth factor was further decreased in injured vessels of diabetic rats as compared to those of non-diabetic rats (p < 0.05). Of note, administration of cilostazol attenuated the decrease in hepatocyte growth factor concentration in injured vessels of both non-diabetic and diabetic rats (p < 0.01). Increase in vascular hepatocyte growth factor by cilostazol was confirmed by in vitro experiments showing that cilostazol increased hepatocyte growth factor concentration in cultured human vascular smooth muscle cells, accompanied by cAMP accumulation. CONCLUSION/INTERPRETATION: Our study shows that the increase in vascular hepatocyte growth factor by cilostazol could improve abnormal growth of vascular smooth muscle cells and endothelial dysfunction through rapid regeneration of endothelial cells.

8-Bromo Cyclic Adenosine Monophosphate↗

PubMed2001

In vivo synergy between green tea extract and levofloxacin against enterohemorrhagic Escherichia coli O157 infection.

We studied the synergistic effects of Japanese green tea extract (JGTE) and levofloxacin (LVFX) against enterohemorrhagic Escherichia coli (EHEC) infection in a gnotobiotic mouse model. Mice fed on JGTE conferred a significant degree of protection against an oral challenge with EHEC. Complete elimination of the bacteria from the mice, was however, difficult. The combination of JGTE and LVFX increased the survival rate and reduced damage to target organs. Thus, dietary supplementation with JGTE improved the therapeutic effects of antibiotic treatment.

Animals↗

PubMed2001

Involvement of the cerebral cortex and autonomic ganglia in Machado-Joseph disease.

Machado-Joseph disease (MJD) is an autosomal dominant neurodegenerative disorder caused by expansion of a polyglutamine tract in the disease protein. In this study of brains from four autopsied MJD patients, we have demonstrated immunohistochemically that expanded polyglutamine stretches largely accumulate as inclusions in neuronal nuclei, and less frequently are distributed in the nucleoplasm in a diffuse pattern. These nuclear abnormalities involved many neurons covering a wide range of central and peripheral nervous system regions, including the cerebral cortex, thalamus and autonomic ganglia that have been categorized previously as spared regions by conventional pathological studies. These lesions, newly recognized by polyglutamine immunohistochemistry, may be responsible for the cerebral cortical dysfunctions or autonomic abnormalities pointed out in MJD patients by the recent clinical and neuroradiological studies.

Adult↗

PubMed2001

Co-localization of alpha-synuclein and phosphorylated tau in neuronal and glial cytoplasmic inclusions in a patient with multiple system atrophy of long duration.

Neuronal and glial cytoplasmic inclusions (NCIs and GCIs), which contain alpha-synuclein as a major component, are characteristic cytopathological features of multiple system atrophy (MSA). We report MSA of 19 years' duration in a 73-year-old woman. Her initial symptom was parkinsonism, with dementia appearing about 8 years later. Postmortem examination showed marked atrophy of the frontal and temporal white matter and limbic system, in addition to the pathology typical of MSA. In the limbic system, severe neuronal loss and astrocytosis were observed, and the remaining neurons often had lightly eosinophilic, spherical cytoplasmic inclusions. Interestingly, a double-labeling immunofluorescence study revealed that the NCIs in the dentate gyrus and amygdaloid nucleus, and the GCIs in the frontal and temporal white matter often expressed both alpha-synuclein NACP-5 and phosphorylated tau AT8 epitopes. Double-immunolabeling electron microscopy of the NCIs in the dentate gyrus and the GCIs in the temporal white matter clearly revealed labeling of their constituent granule-associated filaments with NACP-5, and some of them were also labeled with AT8. These findings strongly suggested that some alpha-synuclein filaments were decorated with phosphorylated tau without formation of fibrils such as paired helical filaments. Immunoblotting of sarkosyl-insoluble tau indicated that the accumulated tau consisted mainly of four-repeat tau isoforms of 383 amino acids and 412 amino acids. We consider that the limbic system can be a major site of neurodegeneration in MSA of long duration. The mechanisms of such abnormal tau accumulation in the NCIs and GCIs are unknown.

Aged↗

PubMed2001

Expression of calbindin D-28k and parvalbumin in cerebral cortical dysgenesis induced by administration of ethylnitrosourea to rats at the stage of neurogenesis.

It has been reported that transplacental administration of ethylnitrosourea (ENU), which is cytotoxic immediately after administration, to rat fetuses at the neurogenesis stage induces dysgenesis of the cerebral cortex, characterized by neuronal sparseness and architectural irregularity. In the present study, we examined the topographic distribution of neurons containing 5-bromo-2-deoxyuridine (BrdU), and those containing calbindin D-28k (CaBP) and parvalbumin (PV), most of latter two are considered to be interneurons located in particular layers of the normal cerebral cortex in rats with experimentally induced cerebral cortical dysgenesis. Pregnant Wistar albino rats were given a single transplacental administration of ENU on embryonic day 16, followed 4, 8, 16, 24, 36, or 48 h later by a single intraperitoneal injection of BrdU. The pups were killed 10 weeks after birth. In the normal cerebral cortex, BrdU-immunopositive neurons showed an inside-out pattern according to the time of BrdU injection, whereas in ENU-treated rats the topographic localization of the BrdU-immunopositive neurons was irregular and the inside-out pattern was disrupted. Although the number of CaBP- and PV-immunopositive neurons was lower in ENU-treated animals, no topographic difference was evident between the normal and the dysgenetic cerebral cortices. These findings indicate that the expression of CaBP and PV in the neurons of the rat cerebral cortex is extrinsic, and depends on the position of the neurons rather than on the time of their formation or on genetic control. This suggests the existence of re-regulation of the expression of CaBP and PV in the developing brain, which may be one of the effective mechanisms by which the cerebral cortex can maintain its normal function in spite of cytoarchitectural abnormality.

Abnormalities, Drug-Induced↗

PubMed2001

Aprosencephaly: histopathological features of the rudimentary forebrain and retina.

Aprosencephaly/atelencephaly is an extremely rare central nervous system defect of the human fetus, which has been attributed to an encephaloclastic process. We report here the histopathological features of the rudimentary forebrain and retina of a case of aprosencephaly in a male fetus that was examined at 20 weeks of gestation, in which there was no evidence of destruction. The prosencephalon was excessively small and replaced by a solid, cylindrical mass without a hemispheric cleavage or a ventricle. Histologically, the rudimentary forebrain tissue consisted of primitive cells that had accumulated in the anterior portion, and of differentiated neurons and glia that were distributed in a random-manner in the posterior portion. The most rostral portion of the tissue penetrated the sphenoidal bone through a single canal: an extracranial ectopic nest consisted of primitive cells that were located at the posterior portion of the face. There were no eyelid openings, eyeballs, or optic nerves, although a nest of dysplastic retinal rosettes and two nests of melanin-pigmented epithelium were identified. This case seems to represent a primary malformation, and the features imply that the failure occurs after neurulation and before the prosencephalic medium began its growth.

Abnormalities, Multiple↗

PubMed2001

Topographic analysis of astigmatism induced by scleral shortening in pig eyes.

BACKGROUND: Corneal astigmatism is a severe postoperative problem in foveal translocation surgery. We evaluated the corneal astigmatism induced by scleral shortening in pig eyes in vitro. METHODS: We created three sizes of scleral shortening in pig eyes and examined the preoperative and postoperative corneal astigmatism. The three sizes of scleral shortening were; 6 mm x 12 mm, 9 mm x 12 mm, and 6 mm x 16 mm (radial x circumferential). The shortenings were created 11 mm from the limbus with 10 eyes in each group. Videokeratographic measurements were performed using the CAS System 2000, preoperatively and postoperatively, and the astigmatism caused by the scleral shortening was evaluated. RESULTS: The surgically-induced astigmatism was 2.1 +/- 1.2 diopters (D) in the 6 mm x 12 mm group, 5.2+/-1.5 D in the 9 mm x 12 mm group, and 3.7+/-1.0 D in the 6 mm x 16 mm group. Corneal astigmatism caused by scleral shortening depended on both the radial and circumferential shortening. Pre- and postoperative topographic corneal maps showed an irregular astigmatism pattern (lazy bowtie pattern). Because the central zone of the cornea showed a relatively regular astigmatism, the corneal astigmatism induced by scleral shortening did not affect the predicted corneal acuity. CONCLUSIONS: In foveal translocation surgery with scleral shortening, an excessive scleral resection in the radial direction can cause clinically intolerable regular and irregular astigmatism. Minimal scleral shortening that will satisfy the required translocated distance is recommended to reduce the risk/benefit ratio.

Animals↗

PubMed2001

Expression and distribution of beta amyloid precursor protein and beta amyloid peptide in reactive astrocytes after transient middle cerebral artery occlusion.

BACKGROUND: In the brains of Alzheimer's disease patients, beta amyloid protein is the major component of senile plaque. In ischemic stress, beta amyloid precursor protein (APP) and beta amyloid peptide are reported to be upregulated. METHOD: Using Male Wistar-ST rats, expression and distribution of APP and beta amyloid peptide were examined immunohistochemically after transient ischemia induced by a 2-h middle cerebral artery occlusion (MCAO). After reperfusion for 3, 7, 14, 30 and 60 days, brains were removed and immunostaining was performed. FINDINGS: The reactive astrocytes with APP were observed in the periphery of infarct from 3 days to 60 days post-occlusion. The immunoreactivity of beta amyloid peptide was also localized in the reactive astrocytes in the peripheral zone of infarct at 7, 14, and 30 days post-occlusion. However, beta amyloid expression was not identified at 3 days or 60 days post MCAO. Transient ischemia temporarily induced beta amyloid peptide expression in reactive astrocytes, but this expression peaked at 30 days and disappeared at 60 days. INTERPRETATION: These findings suggested that beta amyloid peptide was derived from the processing of APP produced in the same reactive astrocytes and the production of the peptide stopped within 60 days after the ischemic stress.

Alzheimer Disease↗

PubMed2001

Interaction between neuronal intranuclear inclusions and promyelocytic leukemia protein nuclear and coiled bodies in CAG repeat diseases.

Neuronal intranuclear inclusions (NIIs) are a pathological hallmark of CAG repeat diseases. To elucidate the influence of NII formation on intranuclear substructures, we investigated the relationship of NIIs with nuclear bodies in brains of dentatorubral-pallidoluysian atrophy and Machado-Joseph disease. In both diseases, promyelocytic leukemia protein, a major component of the promyelocytic leukemia protein nuclear bodies, altered the normal distribution and was rearranged around NII, forming a single capsular structure. We further demonstrated that NIIs were present in close contact with coiled bodies, a highly dynamic domain that may be involved in the biogenesis of small nuclear ribonucleoproteins. The preferential association of intranuclear polyglutamine aggregates with coiled bodies was also confirmed in the dentatorubral-pallidoluysian atrophy transgenic mouse brain and culture cells expressing mutant atrophin-1. The results suggest that the interaction between NIIs and nuclear bodies may play a role in the pathogenesis of CAG repeat diseases.

Adult↗

PubMed2001

Therapeutic effect of anti-TNF-alpha antibody and levofloxacin (LVFX) in a mouse model of enterohemorrhagic Escherichia coli O157 infection.

The ability of an anti-TNF-alpha antibody to confer protection against enterohaemorrhagic Escherichia coli (EHEC) O157 was investigated in germfree IQI mice. The use of an antibiotic levofloxacin (LVFX) alone or with the antibody was also studied. Protection included an increase in survival rate. Treatment with the anti-TNF-alpha antibody inhibited the histological signs associated with EHEC infection but did not prevent the colonization of EHEC or production of Shiga toxin (Stx). No clinical signs were observed and EHEC was completely eliminated in the mouse model receiving both anti-TNF-alpha antibody and LVFX. Anti-TNF-alpha antibody suppressed inflammatory cytokine response in the mouse kidney and brain by EHEC infection.

Animals↗

PubMed2001

High density lipoprotein binding protein of eel (Anguilla japonica) liver with specificity of binding to apoAI as a ligand.

High-density lipoprotein (HDL) binding protein (HBP) was isolated from the microsomal fraction of eel liver homogenate by affinity chromatography with a HDL-column. After SDS-PAGE and blotting, HBP on the PVDF membrane was detected by FITC-labeled HDL and apolipoprotein AI (apoAI) as a ligand. HBP in the microsomal fraction was most abundant among microsomal, mitochondrial and cytosolic fractions. The HBP isolated by a HDL-column consisted of at least three proteins with low molecular weights of 18.5, 14.5 and 13.5 kDa; the main component was 14.5 kDa. These proteins are not products of protease digestion, as the procedure was carried out in the presence of protease inhibitors including (p-aminophenyl) methansulfonyl fluoride, 4-(2-aminoethyl)-benzenesulfonyl fluoride, pepstatin A, E-64, bestatin, leupeptin, aprotinin and EDTA. The HBP specifically bound to FITC-apoAI and faintly bound or did not bind to FITC-apoAII. Furthermore, binding of HDL labeled with lipophilic fluorescence to isolated eel hepatocytes was inhibited by the antibody to apoAI, but not inhibited by the antibody to apolipoprotein AII (apoAII). These results strongly suggest that the HBP isolated from the microsomal fraction is present on the plasma membrane of eel liver and plays important roles for the lipid transport through the interaction with HDL.

Animals↗

PubMed2001

A comparison of the concentrations of C-reactive protein and alpha1-acid glycoprotein in the serum of young and adult dogs with acute inflammation.

The concentrations of C-reactive protein (CRP) and alpha1-acid glycoprotein (AAG) were evaluated in 1-, 3- and 18-month-old dogs (four of each age) that had been inoculated with turpentine oil. The CRP and AAG in 3-month-old and younger dogs subjected to surgery or inoculated with either Staphylococcus aureus or a viral vaccine were also evaluated. The average CRP concentration in the sera peaked 2 days after inoculation of turpentine oil. The peak CRP concentrations in 3- and 18-month-old dogs were significantly (p < 0.05) greater than those in 1-month-old dogs. The average AAG concentration in the sera peaked 4 days after inoculation of turpentine oil. No significant difference was found in AAG concentrations between any of the age groups. When experimentally inoculated with S. aureus or subjected to oophorohysterectomy, the CRP and AAG concentrations increased in 3-month-old dogs, but they increased little in 1-month-old dogs. The CRP and AAG in dogs inoculated with the viral vaccine did not increase. In dogs with fractures or subjected to percutaneous gastrostomy, the CRP and AAG concentrations correlated with the condition of dogs.

Age Factors↗

PubMed2001

Aryl hydrocarbon receptor/dioxin receptor in human monocytes and macrophages.

Aryl hydrocarbon receptor (AhR) belongs to the bHLH/PAS transcription factor family and is activated by various polycyclic or halogenated aromatic hydrocarbons, e.g. 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), 3-methylcholanthrene (3MC). In the present study, we showed that in U937 cells and human macrophages AhR, with its partner cofactor Arnt, is expressed and CYP1A1 mRNA expression is induced in the presence of AhR ligand 3MC. Moreover, we showed that AhR, associating with Arnt, binds to target DNA sequences and activates transcription. Since part of AhR is activated into DNA binding species in the absence of exogenous ligand and competitive AhR antagonist alpha-naphthoflavone inhibits this activation process with reducing CYP1A1 mRNA expression levels, the presence of endogenous ligand is indicated.

Benzoflavones↗

PubMed2001

Physiologic functions of activating natural killer (NK) complex-encoded receptors on NK cells.

Natural killer (NK) cells express a superfamily of surface proteins that share common structural features: dimeric type II integral membrane proteins with extracellular domains resembling C-type lectins. These receptors are encoded by a single genetic region called the NK complex (NKC). The NKC encompasses several families of genes including NKR-PI, Ly-49, CD94/NKG2, and NKG2D. Different NKC-encoded receptors have been shown to activate or to inhibit NK-cell function, and different receptors within the same family can have opposing functions. Within an individual NK cell, inhibitory receptors typically predominate over stimulatory receptors, calling into question the teleologic requirement or physiologic significance of lectin-like activating receptors in NK cells. Despite the widespread expression of inhibitory receptors, however, subtle features of activating receptor biology enable them to stimulate effector functions in vivo and in vitro. Activating receptors and inhibitory receptors differ in their subset expression, in their structural constraints for binding to common ligands, in their ligand repertoires, and in that divergent families of activating receptors utilize different signaling pathways. These subset, binding, repertoire, and signaling diversities may allow activating receptors to manifest their effects in spite of inhibitory receptor functions during pathologic conditions in vivo. In this review, we will present a detailed analysis of the data supporting this hypothesis with particular relevance toward physiologic NK-cell functions.

Amino Acid Sequence↗

PubMed2001

Establishment of gingival epithelial cell lines from transgenic mice harboring temperature sensitive simian virus 40 large T-antigen gene.

We established two gingival epithelial cell lines (GE1 and GE6), originating from transgenic mice harboring the temperature-sensitive simian virus 40 large T-antigen gene. GE1 and GE6 grew at a permissive temperature (33 degrees C) in a pavement arrangement and solely formed multilayers that exhibited morphological features similar to those of the stratified oral epithelium, with neither the use of stromal equivalents nor feeder layers. Both GE cells underwent apoptosis at a non-permissive temperature (39 degrees C). Characteristic keratin peptides, keratin 4 and 13, for mucosal epithelium were obviously expressed in the suprabasal cells, and keratohyalin granules and involucrin were present in the surface flat cells in the multilayered culture. Keratin 10 (one of the markers for higher keratinized gingival epithelium) was rarely found in some uppermost cells, and filaggrin (a component of keratohyalin granules) appeared sparsely in uppermost desquamating cells in the older cultures. These observations indicated that GE1 and GE6 cells exhibited the phenotype characterizing nonkeratinized sulcular epithelium, which possessed the potency undergoing keratinization in such highly stratified cultures as oral gingival epithelium. GE cells increased the expression levels of mRNA of interleukin-1beta and tumor necrosis factor alpha by the stimulation of lipopolysaccharide and extracellular substances of oral streptococci. The GE cell lines thus could serve as an excellent experimental system for further studies on the physiology of gingival epithelium and corresponding diseases, such as periodontal disease, epithelial hyperplasia, and gingival tumors.

Animals↗

PubMed2001

Electrophysiological and neurochemical evidence for voltage-dependent Ca(2+) channel blockade by a novel neuroprotective agent NS-7.

The effects of a neuroprotective agent 4-(4-fluorophenyl)-2-methyl-6-(5-piperidinopentyloxy) pyrimidine hydrochloride (NS-7) on the Ca(2+) currents in rat dorsal root ganglion neurones and on the depolarization-evoked nitric oxide synthesis, which was estimated from cyclic GMP formation in slices of the rat cerebral cortex, were investigated, and its mode of action was compared with those of typical Ca(2+) channel blockers. In rat dorsal root ganglion neurones, NS-7 (0.3-100 microM) inhibited the whole-cell Ba(2+) currents (IBa) in a voltage-dependent manner, in which the compound more potently blocked the IBa elicited from the holding potential of -40 mV than that induced from -80 mV. In slices of rat cerebral cortex, KCl-evoked nitric oxide synthesis was markedly inhibited by omega-conotoxin GVIA and omega-agatoxin IVA, but only slightly attenuated by nifedipine, suggesting that the response is mediated predominantly through activation of N-type and P/Q-type Ca(2+) channels. NS-7 (1-100 microM) inhibited the KCl-stimulated nitric oxide synthesis in a manner dependent on the intensity of the depolarizing stimuli. Moreover, weak but significant inhibitory effect of NS-7 was observed even after wash-out. Similar voltage-dependent inhibition of the KCl response was observed by a limited concentration (10 microM) of verapamil. These findings indicate that NS-7 in several concentrations blocks Ca(2+) channel in a voltage-dependent manner.

Animals↗

PubMed2001

UDP-sugar transporter implicated in glycosylation and processing of Notch.

Glycosylation modifies protein activities in various biological processes. Here, we report the functions of a novel UDP-sugar transporter (UST74C, an alternative name for Fringe connection (Frc)) localized to the Golgi apparatus in cellular signalling of Drosophila. Mutants in the frc gene exhibit phenotypes resembling wingless and Notch mutants. Both Fringe-dependent and Fringe-independent Notch pathways are affected, and both glycosylation and proteolytic maturation of Notch are defective in mutant larvae. The results suggest that changes in nucleotide-sugar levels can differently affect Wingless and two distinct aspects of Notch signalling.

Amino Acid Sequence↗