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Biomedical subjects

K Miyoshi

Publications and source records attributed to K Miyoshi.

At least 55 records · Page 3Linked to original sources
PubMed2000

Spinal intradural perimedullary arteriovenous fistula with varix in infant.

A rare occurrence of type IV spinal arteriovenous malformation (intradural perimedullary arteriovenous fistula) is described in an 18-month-old boy initially misdiagnosed with Guillain-Barré syndrome. An intramedullary mixed-intensity mass lesion at Th1 was demonstrated by magnetic resonance imaging together with flow voids over the dorsal aspect of the swollen spinal cord. Angiography demonstrated an intradural perimedullary arteriovenous fistula including an intraparenchymal vascular pocket. After partial embolisation of the posterior spinal arteries through the left intercostal-radicular artery, the arteriovenous fistula was removed completely together with an organised haematoma. The fistula directly opened into a vascular pocket, which was confirmed pathologically to be a varix. The postoperative course was uneventful, and the patient resumed ambulation within 4 months. The case, subclassifiable as a type IVb spinal perimedullary AVF, was unique given its location and the patient's age at presentation.

Central Nervous System Vascular Malformations↗
PubMed2000

Improvement in development of porcine embryos reconstituted with cells from blastocyst-derived cell lines and enucleated oocytes by optimization of reconstruction methods.

The present study was conducted to establish the most suitable system for producing porcine reconstructed embryos by transferring cells from blastocyst-derived cell lines into enucleated oocytes. When the cells were fused to preactivated metaphase II oocytes, or the cells and arrested metaphase II oocytes were fused in medium without CaCl(2) and MgSO(4), the percentages (43-53%) of fused embryos were significantly lower than those (72-79%) produced by fusing the cells to arrested metaphase II oocytes in medium containing CaCl(2) and MgSO(4). High productive efficiency (7%) of blastocysts was obtained when reconstituted embryos produced by the last method were activated again at 3 hours after fusion (F/A --> Activation). Pronuclear formation was observed in 80-91% of the reconstructed embryos produced by F/A --> Activation, with no significant differences between different culture periods in the medium containing cytochalasin B. When cultured in the medium containing cytochalasin B for 0-1 h, almost all (83-85%) the embryos had one pronucleus and one polar body. However, the number of embryos with two pronuclei and no polar bodies was increased significantly by culturing in the medium containing cytochalasin B for 2-4 h. The cleavage rate (34-48%) of reconstructed embryos was not affected by the presence of cytochalasin B for 2 h after activation. However, the percentage of embryos that developed to the blastocyst stage was significantly higher in the presence (23%) than absence (5%) of cytochalasin B. The results indicate that F/A --> Activation and cytochalasin B treatment are effective for the production of porcine embryos reconstituted with cells from blastocyst-derived cell lines and enucleated oocytes.

Animals↗
PubMed2000

Establishment of a porcine cell line from in vitro-produced blastocysts and transfer of the cells into enucleated oocytes.

The present study was conducted to establish a porcine cell line from blastocysts produced in vitro and to examine the developmental ability of nuclear transfer embryos reconstituted with the cells and enucleated mature oocytes. When hatched blastocysts were cultured in Dulbecco's modified Eagle's medium with supplements, no colonies of embryo-derived cells were observed. In contrast, 56% of embryos that were attached to feeder layers of STO cells formed colonies in NCSU-23 with supplements. When the colonies were subcultured in the absence of feeder cells, a cell line with an epithelial-like cell morphology was obtained. This cell morphology was stable up to at least passage 30. Although no fused embryos were observed when a pulse of 100 V/mm was applied, the fusion rate increased significantly at 150 V/mm (28%) and 200 V/mm (64%). At 200 V/mm, 39% of fused embryos cleaved, but no embryos developed beyond the 3-cell stage. When cocultured with electro-activated oocytes, percentages of reconstructed embryos cleaved (65%) and developed to the 4-cell stage (23%) were significantly higher than percentages for those (cleavage: 38%; 4-cell stage: 3%) in the absence of activated oocytes. At 7 days after culture, one reconstructed embryo successfully developed to the blastocyst stage in the presence of activated oocytes. When green fluorescent protein-expressing cells and enucleated oocytes were fused and the fused embryos were cultured with electro-activated oocytes, 3 of 102 reconstructed embryos developed to the blastocyst stage. All of the blastocysts were positive for fluorescent green under ultraviolet light. The results of the present study indicate that a porcine cell line can be established from the hatched blastocyst and maintained in vitro for a long period, and that reconstructed embryos obtained by transferring the blastocyst-derived cells into enucleated oocytes have the ability to develop to the blastocyst stage in vitro.

Animals↗
PubMed2000

RRS1, a conserved essential gene, encodes a novel regulatory protein required for ribosome biogenesis in Saccharomyces cerevisiae.

A secretory defect causes specific and significant transcriptional repression of both ribosomal protein and rRNA genes (K. Mizuta and J. R. Warner, Mol. Cell. Biol. 14:2493-2502, 1994), suggesting the coupling of plasma membrane and ribosome syntheses. In order to elucidate the molecular mechanism of the signaling pathway, we isolated a cold-sensitive mutant with a mutation in a gene termed RRS1 (regulator of ribosome synthesis), which appeared to be defective in the signaling pathway. The rrs1-1 mutation greatly reduced transcriptional repression of both rRNA and ribosomal protein genes that is caused by a secretory defect. RRS1 is a novel, essential gene encoding a nuclear protein of 203 amino acid residues that is conserved in eukaryotes. A conditional rrs1-null mutant was constructed by placing RRS1 under the control of the GAL1 promoter. Rrs1p depletion caused defects in processing of pre-rRNA and assembly of ribosomal subunits.

Amino Acid Sequence↗
PubMed2000

A new practical strategy for the synthesis of long-chain phosphopeptide.

A new practical strategy has been developed for the synthesis of long-chain phosphopeptide. Both the 2-chlorobenzyloxycarbonyl (CIZ) group for Lys and methyl (Me) for phosphoamino acids remained intact, while other commonly used side-chain protecting groups were cleaved quantitatively, during the reaction using a highly acidic trifluoromethanesulfonic acid (TFMSA)-based reagent system (High TFMSA: TFMSA-TFA-m-cresol=1:9:1, v/v). Selective deprotection of the CIZ and Me group-containing protected phosphopeptide resin with the High TFMSA gave a partially protected phosphopeptide fragment suitable for thioester-mediated fragment condensation. A deprotection protocol of the 9-fluorenylmethyloxycarbonyl (Fmoc) group, which evades significant side reaction toward the protected phosphoamino acid, was also developed. These two new findings enabled us to synthesize long-chain phosphopeptide via thioester-mediated fragment condensation.

Amino Acid Sequence↗
PubMed2000

TAS-301 blocks receptor-operated calcium influx and inhibits rat vascular smooth muscle cell proliferation induced by basic fibroblast growth factor and platelet-derived growth factor.

The purpose of this study was to determine the effect of a recently synthesized drug, TAS-301 [3-bis(4-methoxyphenyl)methylene-2-indolinone], on vascular smooth muscle cell (VSMC) proliferation and the intracellular signal transduction pathways involved in VSMC proliferation. In an in vitro assay, TAS-301 inhibited the proliferation of rat VSMCs stimulated by platelet-derived growth factor (PDGF)-BB, basic fibroblast growth factor, or 2% fetal bovine serum in a concentration-dependent manner. TAS-301 dose-dependently inhibited the PDGF-induced Ca2+ influx; the concentration for the inhibition of Ca2+ influx was nearly identical to that for inhibition of VSMC proliferation. The Ca2+ influx induced by PDGF was also attenuated by NiCl2 but not by nifedipine, suggesting that PDGF-induced Ca2+ influx would be mediated by some non-voltage-dependent mechanisms. Furthermore, TAS-301 inhibited PDGF-induced activation of protein kinase C (PKC) and the phorbol 12-myristate 13-acetate-mediated induction of activator protein 1 (AP-1) in a concentration-dependent manner. These findings indicate that TAS-301 inhibited the proliferation of VSMCs by blocking voltage-independent Ca2+ influx and downstream signals such as the Ca2+/PKC signaling pathway, leading to AP-1 induction.

Animals↗
PubMed2000

Enzyme-linked immunosorbent assays of canine apolipoproteins B-100 and A-I.

An enzyme-linked immunosorbent assay (ELISA) for canine blood apolipoprotein (apo) B-100 and A-I was developed. The working range for the assay was 1.8 to 28.7 ng/well for apoB-100 and it was 50 to 410 ng/well for apoA-I. The intra- and inter-assay coefficients of variation for the assay for apoB-100 were 5.4 and 6.9%, respectively, and for apoA-I they were 5.8 and 10.6%, respectively. The average concentrations of apoB-100 and A-I in 25 beagles (males, aged 3-4 years) were 0.084 +/- 0.028 (mean +/- SD) mg/ ml and 6.29 +/- 1.55 mg/ml, respectively. The ratios of canine (C) apoB-100 to CapoA-I were 1.41 +/- 0.58%. The respective concentrations in one case of hyperlipidemia with systemic atherosclerosis were 0.454 mg/ml and 11.28 mg/ml (a ratio of 4.03%). These values were larger than those of the controls. These results suggest that the measurements of CapoB-100 and A-I concentrations by this newly developed ELISA are helpful for diagnosis of lipidosis.

Animals↗
PubMed2000

Inhibitory effect of TAS-301, a new synthesized constrictive remodeling regulator, on renarrowing after balloon overstretch injury of porcine coronary artery.

The purpose of this study was to determine the efficacy and the possible mechanism of action of a recently synthesized drug, TAS-301 [3-bis(4-methoxyphenyl)methylene-2-indolinone], on stenosis after balloon overstretch injury of porcine arteries. We measured the diameter of vessels by angiography and conducted histological analysis. The oral administration of TAS-301 kept dilated the angiographic luminal diameter of injured segment 4 weeks after overstretch injury and reduced calculated stenosis ratio in a dose-dependent manner, significantly reducing it at doses of 30 and 100 mg/kg. Histopathological analysis showed that TAS-301 significantly reduced the adventitial area at doses of 30 and 100 mg/kg with moderate reduction of the neointimal area, resulting in the larger residual lumen. In an in vitro assay, TAS-301 dose dependently inhibited the proliferation of adventitial fibroblasts stimulated by basic fibroblast growth factor or transforming growth factor-beta(1). In addition, the drug reduced adventitial fibroblast-mediated three-dimensional collagen gel contraction. These findings indicate that TAS-301, the first compound developed for targeting the constrictive remodeling, showed a high inhibitory potency on coronary artery stenosis of micropigs after injury, mainly due to inhibition of adventitial fibroblast proliferation and of the contractile ability of myofibroblasts. Our results suggest the strong possibility that TAS-301 may be efficacious for prevention of restenosis after angioplasty and the need to examine the therapeutic usefulness of this drug in clinical trials.

Angioplasty, Balloon, Coronary↗
PubMed2000

[A patient with motor neuron syndrome clinically similar to amyotrophic lateral sclerosis, presenting spontaneous recovery].

We report a patient with motor neuron syndrome similar to amyotrophic lateral sclerosis (ALS) and with spontaneous recovery. At the age 40, the woman developed progressive muscular weakness, atrophy and fasciculation in extremities. She also noted a dyspnea, tongue atrophy and dysphagia. A neurological examination 6 months after onset revealed i) a tongue atrophy and fasciculation, ii) diffuse muscule weakness and atrophy in face, neck and extremities, and iii) marked hyperreflexia in the four limbs and bilateral Babinski reflex, but iv) neither sensory disturbance nor ophthalmoplegia. Electromyogram (EMG) detected such denervation potentials as fibrillation potentials, fasciculation potentials, positive sharp waves and polyphasic or giant MUPs diffusely in the limb muscles. Peripheral nerve conduction study detected neither conduction block nor delay. Thus, she was diagnosed as suffering from ALS. However, since approximate 1 year after onset, her muscle weakness has gradually been getting better. Simultaneously, the dyspnea and dysphagia gradually improved. Two years after onset, an EMG examination detected chronic denervation potentials in the left musculus sternocleidomastoideus and a few on-going denervation potentials in the left musculus extensor carpi radialis, but no denervation potentials in other limb muscles. Fasciculation potentials were found in tongue muscles. Thus, the present case was thought to have a reversible motor neuron syndrome clinically quite similar to ALS. A mild increase in IgE (346 U/ml) and a low-titer IgM-class anti-GM1 antibody were found in her serum though its pathological significance was uncertain. Any immunological aberrance may account for the pathogenesis. It should be noted that clinically diagnosed cases of ALS may rarely recover spontaneously.

Adult↗
PubMed1999

Construction of Epstein-Barr virus-based expression vector containing mini-oriP.

Epstein-Barr virus (EBV)-based vectors are extrachromosomal vectors carrying a replicational origin, oriP (about 2200 bp) and a replication initiation factor (EBNA-1) which are sufficient for autonomous replication. Because one disadvantage of these vectors is their large sizes, we examined the effect of partial deletion of oriP on the effectiveness of the EBV-based vectors, using an enhanced green fluorescent protein (EGFP) as a reporter to monitor gene expression. Results indicated that 954 bp-deleted mini-oriP is useful in primate cells since the vector showed high efficiency of stable transfection, a high ratio of EGFP-positive cells, and high recovery of intact plasmid DNA from transfected cells.

Animals↗
PubMed1999

Distinctions between microglial cells and peripheral macrophages with regard to adhesive activities and morphology.

Activated microglial cells and peripheral macrophages are hardly distinguishable from the viewpoints of morphology and function. There are various immunological markers common to both microglial cells and peripheral macrophages. In the present study, however, we found that microglial cells have distinct characters in terms of adhesion and morphology. By using a "rheoscope," that is an apparatus to rheologically measure the strength of cell adhesion to substrates, rat microglial cells were found to attach to polystyrene dishes much more weakly than alveolar and peritoneal macrophages. Interferon-gamma (IFNgamma) strengthened the adhesion of alveolar and peritoneal macrophages, whereas it weakened that of microglial cells. Morphological changes of microglial cells induced by IFNgamma were also different from those of peripheral macrophages. Furthermore, alveolar and peritoneal macrophages produced NO in response to IFNgamma, while microglial cells did not. When cultured on astrocyte-derived extracellular matrix (AsECM) in serum-free medium, only microglial cells extended multiple ramified processes. Conversely, alveolar and peritoneal macrophages on AsECM shrunk their ruffling membrane and rounded up. These distinctions between microglial cells and macrophages may reflect differences in cell lineages as well as environments in which individual cells reside.

Animals↗
PubMed1999

A Case of Esophageal Squamous Cell Carcinoma Metastatic to the Breast.

Metastasis to the breast from extramammary malignancies is rare. There are especially few reports of metastasis from esophageal cancer. We report the pathological and autopsy findings of a 44-year-old man with advanced esophageal cancer and a left breast tumor. Squamous cell carcinoma invading the mammary glands wasdemonstrated histologically. Immunostains for ER, PgR, and ErbB-2 were negative. At autopsy, metastatic lesions were found in lung, liver, diaphragm, peritoneum, spine, and mediastinal lymph nodes, with no evidence of metastasis to the skin. While metastatic breast tumors are rarely the initial sign of malignancy, it isimportant to distinguish a metastasis from primary breast cancer to avoid unnecessary conflicting treatments.

Journal Article↗
PubMed1999

Effect of hyaluronic acid on the development of porcine 1-cell embryos produced by a conventional or new in vitro maturation/fertilization system.

In pigs, it is difficult to produce normal fertilized embryos from immature oocytes in vitro. However, a new maturation/fertilization system in which the percentage of normal fertilized embryos is comparatively high has been developed recently. In the present study, porcine 1-cell embryos were produced both by a conventional and a new system and then cultured in NCSU-23 supplemented with hyaluronic acid at various concentrations. In the conventional system, the percentage of oocytes with monospermic penetration and 1 male pronucleus and 1 female pronucleus was only 6%. At 144 h after insemination, the percentage (5%) of embryos developing to the blastocyst stage in medium supplemented with 0.5 mg/mL hyaluronic acid was significantly (P<0.05) higher than that (2%) in medium without hyaluronic acid. When oocytes were matured and inseminated using the new system, monospermic penetration and the formation of 1 male and 1 female pronucleus were observed in 69% of the penetrated oocytes. However, blastocyst formation (8 to 14%) at 144 h after insemination was not affected by the concentration (0 to 1.0 mg/mL) of hyaluronic acid. These results indicate that the effect of hyaluronic acid on the development of in vitro-produced porcine embryos varies with the conditions of oocyte maturation and fertilization.

Animals↗
PubMed1999

The influence of psychotic states on the autonomic nervous system in schizophrenia.

Abnormal autonomic activity in patients with schizophrenia has been reported, but how psychotic states influence the autonomic nervous system (ANS) has remained unclear due to methodological limitations. The influence of psychotic states on ANS activity in patients with schizophrenia was investigated using a recently developed method of analysis based on heart rate variability which assesses cardiac sympathetic and parasympathetic function separately. Cardiac autonomic function (CAF), together with psychotic states, was assessed at the beginning and the end of an 8-week study period in 53 patients with chronic schizophrenia. The CAF in age- and sex-matched control subjects was also examined. There were no significant differences between the patients and the control subjects in the mean R-R interval (RRI) or in the indices of the sympathetic and the parasympathetic function. In the patients who changed in psychotic states, the parasympathetic index was significantly decreased without significant changes in the sympathetic index when their psychotic states were more pronounced, suggesting psychotic states suppressed the parasympathetic function without affecting the sympathetic function. In these patients, the mean RRI was smaller when their psychotic states were more pronounced. Our results demonstrate that psychotic states affect the ANS, suggesting a relationship between cerebral cognitive and peripheral ANS activities, and that this is presumably mediated through the parasympathetic nervous system. These findings are discussed in comparison with previous reports on the CAF in schizophrenia.

Adult↗
PubMed1999

Presenilin-1 mutations downregulate the signalling pathway of the unfolded-protein response.

Missense mutations in the human presenilin-1 (PS1) gene, which is found on chromosome 14, cause early-onset familial Alzheimer's disease (FAD). FAD-linked PS1 variants alter proteolytic processing of the amyloid precursor protein and cause an increase in vulnerability to apoptosis induced by various cell stresses. However, the mechanisms responsible for these phenomena are not clear. Here we report that mutations in PS1 affect the unfolded-protein response (UPR), which responds to the increased amount of unfolded proteins that accumulate in the endoplasmic reticulum (ER) under conditions that cause ER stress. PS1 mutations also lead to decreased expression of GRP78/Bip, a molecular chaperone, present in the ER, that can enable protein folding. Interestingly, GRP78 levels are reduced in the brains of Alzheimer's disease patients. The downregulation of UPR signalling by PS1 mutations is caused by disturbed function of IRE1, which is the proximal sensor of conditions in the ER lumen. Overexpression of GRP78 in neuroblastoma cells bearing PS1 mutants almost completely restores resistance to ER stress to the level of cells expressing wild-type PS1. These results show that mutations in PS1 may increase vulnerability to ER stress by altering the UPR signalling pathway.

Alzheimer Disease↗
PubMed1999

Superovulation of immature hypothyroid rdw rats by thyroxine therapy and the development of eggs after in vitro fertilization.

The aim of this study was to examine the effect of thyroxine on ovulation in immature rdw rats and the fertilization and development of the eggs. Serum thyroxine concentrations at 30 days of age were significantly lower in rdw rats than in normal rats (P < 0.001), and greatly increased after thyroxine replacement therapy (P < 0.001). Although few eggs (1-5 +/- 1-2) were obtained from immature rdw rats treated with gonadotrophins alone, females treated with gonadotrophins and thyroxine ovulated significantly more eggs (85 +/- 5). As a control, normal littermates ovulated 21-45 eggs when treated with gonadotrophins alone, and 68 eggs when administered with gonadotrophins and thyroxine. Of the eggs collected from rdw rats treated with gonadotrophins and thyroxine, and inseminated with spermatozoa from mature F1 males, 98% were penetrated and in almost all (99%) of these eggs, male and female pronuclei formed. Forty-seven per cent of the pronuclear eggs developed to the blastocyst stage in vitro. After transfer to recipients, 21% (14/66) of one-cell and 22% (8/37) of two-cell embryos developed to offspring, and 62% (8/13) of pups were of rdw/rdw genotype. The average body weight (6.9 versus 7.8 g) of offspring derived from one-cell embryos was lower than that for two-cell embryos. The morulae and blastocysts did not develop to term, although 41% implanted in the uterine horns of recipients. In conclusion, in immature rdw rats, superovulation was induced by gonadotrophins combined with thyroxine therapy and the superovulated oocytes were fertilized and developed in vitro and developed to term after embryo transfer.

Analysis of Variance↗