Biomedical subjects

K Yagi

Publications and source records attributed to K Yagi.

At least 73 records · Page 4Linked to original sources

PubMed2001

Photosensitivity in relation to epileptic syndromes: asurvey from an epilepsy center in Japan.

PURPOSE: We examined the incidence and distribution of photosensitivity among the different age groups and different types of epilepsies and epileptic syndromes. Furthermore, we considered the influence of ethnic and geographic factors on the incidence of photoparoxysmal response (PPR) in epilepsy patients. METHODS: We analyzed the responses to intermittent photic stimulation (IPS) by using a Grass PS22 or PS33 photic stimulator for in 2,187 unselected patients with epilepsy who were treated in our center. RESULTS: The classic PPR was elicited in 37 (1.7%) patients. The mean age of these 37 patients was 17.0 years. The subpopulation of patients having PPR included 2.0% of all patients with symptomatic generalized epilepsy. 5.6% (p < 0.01) of those with idiopathic generalized epilepsy, 0.7% of those with symptomatic localization-related epilepsy, and 2.9% of those with undetermined epilepsy. PPR accounted for 17.4% (p < 0.01) of the patients with juvenile myoclonic epilepsy, 7.6% (p < 0.01) of those with grand mal on awakening, and 6.1% (p < 0.01) of those with symptomatic occipital lobe epilepsy. The incidence of PPR increased in patients up to age 15 years, and suddenly decreased after age 20 years. CONCLUSION: The present study presents the first report from eastern Asia, analyzing the incidence of PPR with a restricted definition comparable to the other studies, and the rate of PPR was relatively low compared with the studies performed in the European countries. We could confirm the clear relation between age and positive PPR.

Adolescent↗

PubMed2001

Contrasting effects of zonisamide and acetazolamide on amygdaloid kindling in rats.

PURPOSE: Zonisamide (ZNS) and acetazolamide (AZM) are two antiepileptic drugs (AEDs) that differ in clinical efficacy. To elucidate the mechanisms of action of these compounds, we investigated their therapeutic and prophylactic effects in rats by using a kindling model of partial epilepsy. METHODS: Electrodes were implanted into the left amygdala of adult male Wistar rats. The animals were stimulated at the afterdischarge threshold until five stage 5 seizures were induced. The generalized seizure threshold was then determined. Therapeutic effects were examined in rats manifesting successive convulsions with near-threshold stimulation. To test prophylactic effects, drugs were administered intraperitoneally before daily kindling stimulation until the animal had a stage 5 seizure or reached day 18. RESULTS: ZNS (10-40 mg/kg; n=6) suppressed kindled seizures in a dose-dependent manner. Repeated administration for 7 days produced tolerance to anticonvulsive effects. AZM (25-200 mg/kg; n=7) showed limited therapeutic effect, alleviating only the clonic convulsion in stage 5 seizures and reducing afterdischarge duration. Secondary generalization was not significantly suppressed during repeated treatment (50-200 mg/kg; n=6). ZNS, 25 or 40 mg/kg (n=8), significantly retarded seizure development; 15.0 or 17.0 daily stimulations were required to produce a stage 5 seizure. AZM, 50-200 mg/kg (n=6), also retarded seizure development, with 14.0-14.8 stimulations required. CONCLUSIONS: ZNS exhibited modest therapeutic and prophylactic effects, whereas AZM showed mainly prophylactic effects. Hypotheses are presented that may explain the mechanisms of action of these drugs.

Acetazolamide↗

PubMed2001

Nonsteroidal anti-inflammatory drug-associated colitis with a histology of collagenous colitis.

Here we report a case of nonsteroidal anti-inflammatory drug (NSAID)-associated colitis with a histology of collagenous colitis in a 77-year-old woman. The patient had taken aspirin since 1993 after being diagnosed at another hospital, as having multiple cerebral infarctions. She began to suffer from intermittent diarrhea in April 1999. Serological examination showed hypoproteinemia, which indicated that she had protein-losing enteropathy. By July 1999, she had undergone colonoscopic examination four times. Biopsy specimens taken during the fourth colonoscopy revealed collagenous colitis. As the patient had been taking aspirin for 6 years, she was diagnosed as having NSAID-associated colitis with a histology of collagenous colitis. When she stopped taking aspirin, the diarrhea ceased. Three months later, the patient underwent a fifth colonoscopy. A histological examination of the biopsy specimen revealed that the collagen band had vanished. NSAID-associated colitis sometimes shows collagenous colitis histologically and is cured by withdrawing the drug. It is important to differentiate NSAID-associated colitis, even if it shows a histology of collagenous colitis, from collagenous colitis as the two diseases differ in etiology and therapy.

Aged↗

PubMed2001

Chitosan induces apoptosis via caspase-3 activation in bladder tumor cells.

Recently, because of its low toxicity and biological effects, chitosan has been widely used in the medical and pharmaceutical fields, e.g., for nasal or oral delivery of peptide or polar drug delivery. Here, we report a growth-inhibitory effect of chitosan on tumor cells. The growth inhibition was examined by WST-1 colorimetric assay and cell counting. We also observed DNA fragmentation, which is characteristic of apoptosis, and elevated caspase-3-like activity in chitosan-treated cancer cells. The findings suggest that chitosan may have potential value in cancer therapy.

Antineoplastic Agents↗

PubMed2001

Axin facilitates Smad3 activation in the transforming growth factor beta signaling pathway.

Axin acts as a negative regulator in Wnt signaling through interaction with various molecules involved in this pathway, including beta-catenin, adenomatous polyposis coli, and glycogen synthase kinase 3beta. We show here that Axin also regulates the effects of Smad3 on the transforming growth factor beta (TGF-beta) signaling pathway. In the absence of activated TGF-beta receptors. Axin physically interacted with Smad3 through its C-terminal region located between the beta-catenin binding site and Dishevelled-homologous domain. An Axin homologue, Axil (also called conductin), also interacted with Smad3. In the absence of ligand stimulation, Axin was colocalized with Smad3 in the cytoplasm in vivo. Upon receptor activation, Smad3 was strongly phosphorylated by TGF-beta type I receptor (TbetaR-I) in the presence of Axin, and dissociated from TbetaR-I and Axin. Moreover, the transcriptional activity of TGF-beta was enhanced by Axin and repressed by an Axin mutant which is able to bind to Smad3. Axin may thus function as an adapter of Smad3, facilitating its activation by TGF-beta receptors for efficient TGF-beta signaling.

Adaptor Proteins, Signal Transducing↗

PubMed2001

Binary specification of nerve cord and notochord cell fates in ascidian embryos.

In the ascidian embryo, the nerve cord and notochord of the tail of tadpole larvae originate from the precursor blastomeres for both tissues in the 32-cell-stage embryo. Each fate is separated into two daughter blastomeres at the next cleavage. We have examined mechanisms that are responsible for nerve cord and notochord specification through experiments involving blastomere isolation, cell dissociation, and treatment with basic fibroblast growth factor (bFGF) and inhibitors for the mitogen-activated protein kinase (MAPK) cascade. It has been shown that inductive cell interaction at the 32-cell stage is required for notochord formation. Our results show that the nerve cord fate is determined autonomously without any cell interaction. Presumptive notochord blastomeres also assume a nerve cord fate when they are isolated before induction is completed. By contrast, not only presumptive notochord blastomeres but also presumptive nerve cord blastomeres forsake their default nerve cord fate and choose the notochord fate when they are treated with bFGF. When the FGF-Ras-MAPK signaling cascade is inhibited, both blastomeres choose the default nerve cord pathway, supporting the results of blastomere isolation. Thus, binary choice of alternative fates and asymmetric division are involved in this nerve cord/notochord fate determination system, mediated by FGF signaling.

Animals↗

PubMed2001

Large-scale cDNA analysis of the maternal genetic information in the egg of Halocynthia roretzi for a gene expression catalog of ascidian development.

The ascidian egg is a well-known mosaic egg. In order to investigate the molecular nature of the maternal genetic information stored in the egg, we have prepared cDNAs from the mRNAs in the fertilized eggs of the ascidian, Halocynthia roretzi. The cDNAs of the ascidian embryo were sequenced, and the localization of individual mRNA was examined in staged embryos by whole-mount in situ hybridization. The data obtained were stored in the database MAGEST (http://www.genome.ad.jp/magest) and further analyzed. A total of 4240 cDNA clones were found to represent 2221 gene transcripts, including at least 934 different protein-coding sequences. The mRNA population of the egg consisted of a low prevalence, high complexity sequence set. The majority of the clones were of the rare sequence class, and of these, 42% of the clones showed significant matches with known peptides, mainly consisting of proteins with housekeeping functions such as metabolism and cell division. In addition, we found cDNAs encoding components involved in different signal transduction pathways and cDNAs encoding nucleotide-binding proteins. Large-scale analyses of the distribution of the RNA corresponding to each cDNA in the eight-cell, 110-cell and early tailbud embryos were simultaneously carried out. These analyses revealed that a small fraction of the maternal RNAs were localized in the eight-cell embryo, and that 7.9% of the clones were exclusively maternal, while 40.6% of the maternal clones showed expression in the later stages. This study provides global insights about the genes expressed during early development.

Animals↗

PubMed2001

Synergistic effects of different bone morphogenetic protein type I receptors on alkaline phosphatase induction.

Bone morphogenetic proteins (BMPs) are members of the transforming growth factor-beta superfamily, which regulate the differentiation of osteoprogenitor cells. Here we show that among members of the BMP family, BMP-4 and growth/differentiation factor 5 (GDF-5) induce osteoblast differentiation through the activation of three receptor-regulated Smads (i.e. Smad1, Smad5 and Smad8). By contrast, BMP-6 and BMP-7 induce alkaline phosphatase activity through Smad1 and Smad5, but not through Smad8. Consistent with these findings, BMP-4 induced phosphorylation and nuclear translocation of Smad1, Smad5 and Smad8, but BMP-6 activated only Smad1 and Smad5. BMP-4 and GDF-5 are known to bind to activin receptor-like kinase 3 (ALK-3) and/or ALK-6 (also termed BMP type IA and type IB receptors, respectively), whereas BMP-6 and BMP-7 preferentially bind to ALK-2. Compared with the effects induced by only one of the type I receptors, the combination of constitutively active forms of ALK-2 and ALK-3 (or ALK-6) more strongly induced alkaline phosphatase activity in C2C12 cells. Moreover, addition of BMP-4 and BMP-6 to C2C12 cells resulted in higher alkaline phosphatase activity than that of only one of these BMPs. The combination of ALK-2 and ALK-3 also induced higher transcriptional activity than either receptor alone. Thus, ALK-2 and ALK-3 (or ALK-6) might synergistically induce osteoblast differentiation of C2C12 cells, possibly through efficient activation of downstream signaling pathways.

Activin Receptors↗

PubMed2001

Evidence for the presence of DNA-binding proteins involved in regulation of the gene expression of indole-3-pyruvic acid decarboxylase, a key enzyme in indole-3-acetic acid biosynthesis in Azospirillum lipoferum FS.

We isolated the ipdc gene coding for indole-3-pyruvic acid decarboxylase (IPDC), a key enzyme in the indole-3-pyruvic acid pathway for indole-3-acetic acid biosynthesis, in the plant growth-promoting rhizobacterium Azospirillum lipoferum FS. Gel mobility-shift assay showed the presence of two DNA-binding proteins that might be involved in regulation of the ipdc gene expression.

Azospirillum↗

PubMed2001

Isolation and identification of antheridiogens in the ferns, Lygodium microphyllum and Lygodium reticulatum.

Antheridiogens in culture media of 6-week-old prothallia of two species of Schizaeaceous ferns, Lygodium microphyllum and Lygodium reticulatum, were analyzed by gas chromatography-mass spectrometry. In both species, the gibberellin A73 methyl ester (GA73-Me) was identified as the most abundant antheridiogen, and the methyl esters of GA9 and of several monohydroxy-GA73 derivatives were also detected. Since both species produced antheridiogens at a high level, they were classified into high-antheridiogen-producing ferns. The response to GA73-Me of gametophytes of both species is also discussed.

Ferns↗

PubMed2001

Substrate specificity of beta-primeverosidase, a key enzyme in aroma formation during oolong tea and black tea manufacturing.

We synthesized nine kinds of diglycosides and a monoglycoside of 2-phenylethanol to investigate the substrate specificity of the purified beta-primeverosidase from fresh leaves of a tea cultivar (Camellia sinensis var. sinensis cv. Yabukita) in comparison with the apparent substrate specificity of the crude enzyme extract from tea leaves. The crude enzyme extract mainly showed beta-primeverosidase activity, although monoglycosidases activity was present to some extent. The purified beta-primeverosidase showed very narrow substrate specificity with respect to the glycon moiety, and especially prominent specificity for the beta-primeverosyl (6-O-beta-D-xylopyranosyl-beta-D-glucopyranosyl) moiety. The enzymes hydrolyzed naturally occurring diglycosides such as beta-primeveroside, beta-vicianoside, beta-acuminoside, beta-gentiobioside and 6-O-alpha-L-arabinofuranosyl-beta-D-glucopyranoside, but were unable to hydrolyze synthetic unnatural diglycosides. The purified enzyme was inactive toward 2-phenylethyl beta-D-glucopyranoside. The enzyme hydrolyzed each of the diglycosides into the corresponding disaccharide and 2-phenylethanol. These results indicate the beta-primeverosidase, a diglycosidase, to be a key enzyme involved in aroma formation during the tea manufacturing process.

Carbohydrate Sequence↗

PubMed2001

Isolation and identification of 2-phenylethyl disaccharide glycosides and mono glycosides from rose flowers, and their potential role in scent formation.

2-Phenylethyl 6-O-alpha-L-arabinofuranosyl-beta-D-glucopyranoside (1), and its 6-O-beta-D-xylopyraranosyl-beta-D-glucopyranoside (2) were identified in the flowers of Rosa damascena Mill. harvested at the full bloom stage. 2-Phenylethyl beta-D-glucopyranoside (3) and its beta-D-galactopyranoside (4) together with 1 and 2 were also found in the flower buds harvested 44 hrs before the opening stage. Their potential role in scent formation is discussed.

Gas Chromatography-Mass Spectrometry↗

PubMed2001

Seasonal changes in serum total thyroxine, free thyroxine, and canine thyroid-stimulating hormone in clinically healthy beagles in Hokkaido.

The purpose of this study was to evaluate seasonal influences on thyroid hormone levels of healthy outdoor dogs in Hokkaido. We surveyed serum basal total thyroxine (tT4), free thyroxine (fT4), and canine thyroid-stimulating hormone (cTSH) levels, and tT4 levels after administration of TSH for a year. Basal tT4 levels decreased in January, and increased in August and September. fT4 levels increased in January and November. No significant seasonal variation was found in cTSH. tT4 levels after administration of TSH in August and November increased. These results suggested that the thyroid gland may have been activated in November. We should take seasonal variation into consideration when thyroid function is tested.

Animals↗

PubMed2001

Antiatherogenic mitochondrial genotype in patients with type 2 diabetes.

OBJECTIVE: To evaluate the significance of a longevity-associated mitochondrial genotype (Mt5178A) derived from a C --> A transversion at nucleotide position 5178 of mitochondrial DNA, which causes a Leu-to-Met substitution within the NADH dehydrogenase subunit 2 gene, in type 2 diabetic subjects. RESEARCH DESIGN AND METHODS: Mt5178 typing was done by polymerase chain reaction-restriction fragment-length polymorphism with the restriction enzyme AluI in 1,148 type 2 diabetic Japanese subjects, and the results were compared with the clinical characteristics. Then, the association of Mt5178 type with early atherosclerotic changes of the bilateral carotid arteries on ultrasonography was assessed in 412 diabetic subjects randomly selected from the original 1,148 type 2 diabetic subjects, while maintaining the same frequency of Mt5178A and Mt5178C. RESULTS: The frequency of Mt5178A in the type 2 diabetic subjects (454 of 1,148; 40%) was not different from that previously found in healthy blood donors (114 of 252; 45%). Clinical characteristics regarding diabetes were not significantly different between the Mt5178A group (n = 454) and the Mt5178C group (n = 694). However, the mean intima-media thickness (IMT) at six sites in the bilateral carotid arteries was significantly smaller in the Mrt5178A group than in the Mt5178C group (0.906 +/- 0.018 vs. 0.995 +/- 0.021 mm, mean +/- SEM, P = 0.022), and the Mt5178 type was significantly correlated with both the mean IMT and the presence of plaque on multiple regression analysis and discriminant analysis. CONCLUSIONS: The Mt5178A genotype may be unrelated to the etiology of type 2 diabetes. However, Mt5178A seems to have an antiatherogenic effect, at least in type 2 diabetic individuals.

Adult↗

PubMed2001

Homology study of two polyhydroxyalkanoate (PHA) synthases from Pseudomonas aureofaciens.

Recently, we have cloned and analyzed two polyhydroxyalkanoate (PHA) synthase genes (phaC1 and phaC2 in the pha cluster) from Pseudomonas aureofaciens. In this report, the deduced amino acid (AA) sequences of PHA synthase 1 and PHA synthase 2 from P. aureofaciens are compared with those from three other bacterial strains (Pseudomonas sp. 61-3, P. oleovorans and P. aeruginosa) containing the homologous pha cluster. The level of homology of either PHA synthase 1 or PHA synthase 2 was high with each enzyme from these three bacterial strains. Furthermore, multialignment of PHA synthase AA sequences implied that both enzymes of PHA synthase 1 and PHA synthase 2 were highly conserved in the four strains including P. aureofaciens.

Acyltransferases↗

PubMed2001

[Neuroimaging and electrophysiological study in epilepsy].

There exist various morphological and biochemical changes closely associated with electrophysiological phenomena which cause epileptic seizures in the brains of epilepsy patients. Recent developments in investigation methods, not only electrophysiological(EEG and MEG), but also neuroimaging involving morphological imaging(CT and conventional MRI) and functional imaging(SPECT, PET, functional MRI and MRS) is able to demonstrate these changes. SPECT and PET can particularly clarify the changes of cerebral blood flow and glucose metabolism between interictal and ictal periods. In our experience of 423 patients who underwent epilepsy surgery for intractable seizures, these interventions provide important information to identify the epileptogenic foci. However, in practice, discordance in the results of these presurgical evaluations is recognized, and invasive intracranial recordings are needed in such cases. These problems in diagnosis were shown especially in patients with mesial temporal sclerosis and focal cortical dysplasia. To detect an epileptogenic focus more clearly, a combination of morphological and functional findings, new functional imaging such as neurotransmitter receptor imaging, EEG-triggered or neuropharmacological functional MRI, as well as, statistical parametric analysis may be needed.

Electroencephalography↗

PubMed2001

[Fatal stenosis of trachea and main bronchus due to compression by the spine and sternum in three patients with severe motor and intellectual disabilities].

Three patients with severe motor and intellectual disabilities developed fatal respiratory insufficiencies caused by stenosis of the trachea and main bronchus due to compression by the spine and trachea. The onset of respiratory insufficiency was by 20, 16, and 29 years of age. Chest computed tomography demonstrated deformation and narrowing of the trachea and main bronchus, and shortening of the distance between spine and sternum. Although respiratory insufficiency was temporarily relieved by insertion of a stent into the main bronchus in patient 1, he died at the age of 21 due to proliferation of granulation tissue. Patient 2 died of bleeding from the granulation tissue around the window of tracheotomy at the age of 18 years, and patient 3 died of recurrent pneumonia at the age of 34 years. In conclusion, stenosis of the trachea and bronchus observed in these patients was caused by progressive deformation of the thorax. The stenosis may result in sudden death or recurrent respiratory infections in patients with severe motor and intellectual disabilities.

Adolescent↗

PubMed2001

[CD34+ progenitor cell transplantation from HLA-mismatched donors to two patients with chronic active Epstein-Barr virus infection].

We report two boys with chronic active Epstein-Barr virus infection (CAEBV) refractory to conventional chemotherapy, who received HLA-mismatched allografts of CD34-positive progenitor cells from their fathers. One patient developed veno-occlusive disease (VOD) of the liver on day 18 after transplantation and died on day 26. The other patient received the allograft during partial remission. Although he suffered recurrent infections due to Streptococcus viridans, he is now doing well 23 months after transplantation. CAEBV refractory to chemotherapy is considered to be a fatal EBV-infected T/NK-cell lymphoproliferative disease, and our experiences suggest that CD34-positive progenitor cell transplantation for patients with CAEBV lacking HLA-matched donors may be a feasible and useful treatment. However, the timing of transplantation is considered to be critical, and should be performed when the patient is in good clinical condition.

Antigens, CD34↗