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Biomedical subjects

T Mizuno

Publications and source records attributed to T Mizuno.

At least 109 records · Page 6Linked to original sources
PubMed2000

Peroxisomal and mitochondrial targeting of serine:pyruvate/alanine:glyoxylate aminotransferase in rat liver.

Serine:pyruvate/alanine:glyoxylate aminotransferase (SPT or SPT/AGT) of rat liver is a unique enzyme of dual subcellular localization, and exists in both mitochondria and peroxisomes. To characterize a peroxisomal targeting signal of rat liver SPT, a number of C-terminal mutants were constructed and their subcellular localization in transfected COS-1 cells was examined. Deletion of C-terminal NKL, and point mutation of K2 (the second Lys from the C-terminus), K4 and E15 caused accumulation of translated products in the cytoplasm. This suggests that the PTS of SPT is not identical to PTS1 (the C-terminal SKL motif) in that it is not restricted to the C-terminal tripeptide. In vitro synthesized precursor for mitochondrial SPT was highly sensitive to the proteinase K digestion, whereas peroxisomal SPT (SPTp) was fairly resistant to the protease. In in vitro import experiment with purified peroxisomes, however, SPTp recovered in the peroxisomal fraction was very sensitive to the protease. These results suggest that the mitochondrial precursor is synthesized as an unfolded form and is translocated into the mitochondrial matrix, whereas SPTp is synthesized as a folded form and its conformation changes to an unfolded form just before translocation into peroxisomes.

Animals↗
PubMed2000

Scirrhous cancer of the stomach which survived for more than five years after neoadjuvant chemotherapy with UFT (uracil and tegafur) and cisplatin.

A 68-year-old man was diagnosed as having a scirrhous cancer of the stomach. Carcinomatous peritonitis was suspected on abdominal CT examination. Three courses of uracil and tegafur (UFT)/cisplatin (CDDP) chemotherapy were administered. The primary foci were reduced in size, then total gastrectomy was performed. Histological findings revealed a poorly differentiated adenocarcinoma with scirrhous invasion into the subserosa. Histological efficacy of the chemotherapy was judged to be grade 2. The patient has been alive without disease for more than five years after total gastrectomy. Neoadjuvant chemotherapy with UFT and CDDP may have contributed to the favorable clinical outcome in this patient.

Adenocarcinoma, Scirrhous↗
PubMed2000

Quantification of viral ribonucleic acid in plasma of cats naturally infected with feline immunodeficiency virus.

OBJECTIVE: To assess plasma viral RNA concentration in cats naturally infected with feline immunodeficiency virus (FIV). ANIMALS: 28 FIV-infected cats. PROCEDURE: Cats were categorized into 1 of the 3 following stages on the basis of clinical signs: asymptomatic (nonclinical) carrier (AC; n = 11), acquired immunodeficiency syndrome-related complex (ARC; 9), or acquired immunodeficiency syndrome (AIDS; 8). Concentration of viral RNA in plasma (copies per ml) was determined by use of a quantitative competitive polymerase chain reaction (QC-PCR) assay. Total lymphocyte count, CD4+ cell and CD8+ cell counts, and the CD4+ cell count-to-CD8+ cell count ratio were determined by use of flow cytometry. RESULTS: Plasma viral RNA concentration was significantly higher in cats in the AIDS stage, compared with cats in AC and ARC stages. Most (5/7) cats in the AIDS stage had low total lymphocyte, CD4+ cell, and CD8+ cell counts. CONCLUSIONS AND CLINICAL RELEVANCE: Concentration of plasma viral RNA is a good indicator of disease progression in FIV-infected cats, particularly as cats progress from the ARC to the AIDS stage. Determination of CD4+ and CD8+ cell counts can be used as supportive indicators of disease progression.

Animals↗
PubMed2000

B-535a, b and c, new sphingosine kinase inhibitors, produced by a marine bacterium; taxonomy, fermentation, isolation, physico-chemical properties and structure determination.

In the course of our screening for inhibitors of sphingosine kinase, we found a series of active compounds in a culture broth of a novel marine bacterium, SANK 71896. The structures of the compounds, named B-5354a, b and c, were elucidated by a combination of spectroscopic analyses to be new esters of 4-amino-3-hydroxybenzoic acid with long-chain unsaturated alcohols. B-5354a, b and c inhibit sphingosine kinase activity with IC50 values of 21, 58 and 38 microm, respectively.

4-Aminobenzoic Acid↗
PubMed2000

[Twenty-three cases of primary cornea guttata].

PURPOSE: To evaluate the clinical aspects of patients with primary cornea guttata and the morphology of their corneal endothelial cells. METHODS: Twenty-three patients who visited Kanazawa Medical University Hospital or related hospitals in Ishikawa or Fukui prefectures and were diagnosed as having primary cornea guttata by slit lamp microscopy and contact specular microscopy underwent an analysis of corneal endothelial cells as well as their clinical status. RESULTS: In 23 cases, the number of men and young people under 30 years of age was low, with 4 and 2 cases respectively. There was no visual impairment due to cornea guttata. In the specular microscopic findings, the size and density of dark areas varied according to each case and there was asymmetry in some cases. The parameters of the endothelial cells, comprising mean cell area, hexagonality, and the coefficient of variation, were almost within normal limits except for 1 eye of a 79-year-old man who was speculated to be at an early stage of Fuchs' endothelial corneal dystrophy. Three cases had received cataract surgery, but showed no statistical changes in endothelial morphology before or after the surgery. CONCLUSION: Cornea guttata is thought to be a disease which is not uncommon in Japanese people and which does not bring about visual impairment or abnormalities in corneal endothelial cell parameters except for a small number of patients. Such cases with remarkably decreased cell densities should be considered to be at an early stage of Fuchs' dystrophy.

Adult↗
PubMed2000

A study of colloidal scintigraphy in alcoholic liver diseases: discordance from asialo-scintigraphic findings.

BACKGROUND: Our study was undertaken to check the discordance between findings from 99mTc-Sn colloidal reticuloendothelial scintigraphy (RESS) and 99mTc-GSA asialo-scintigraphy (GSA, a technique for evaluation of liver parenchymal cell density and function) and to analyze the discordance in relation to functional disturbances. We compared data between patients with alcoholic liver diseases (ALD) and patients with viral liver diseases (VLD). METHODS: The subjects of this study were 40 patients with chronic liver disease (17 with ALD and 23 with VLD). We used the liver uptake ratio of the tracer of the Sn colloid (SnL15, %), the liver uptake rate (GSAL15, %), and the Rmax (an indicator of total liver receptors) as indices of liver scans. RESULTS: GSAL15 was sometimes nondiscordant from SnL15. The patients were divided into two groups: the nondiscordant group (26 cases where the balance/sum of the two variables was <25%) and the discordant group (14 cases where the balance/sum was > or =25%). SnL15 was 41.6 +/- 16.2% in the nondiscordant group and 42.7 +/- 16.3% in the discordant group (p = 0.80). GSAL15 was 34.3 +/- 12.1% in the nondiscordant group and 21.5 +/- 8.1% in the discordant group (p = 0.001). Rmax was 0.33 +/- 0.17 in the nondiscordant group and 0.113 +/- 0.008 in the discordant group (p = 0.002). Thus, the SnL15, as determined by RESS, did not differ significantly between the nondiscordant and discordant groups, whereas GSAL15 was significantly unfavorable in the discordant group as compared with the nondiscordant group. SnL15 as determined by RESS did not differ significantly between the ALD group (40.4 +/- 18.7%) and the VLD group (43.5 +/- 15.0%) (p = 0.59), whereas Rmax as determined by GSA was significantly improved in the ALD group (0.34 +/- 0.20) compared with the VLD group (0.20 +/- 0.4) (p = 0.02). CONCLUSIONS: Liver cell function was lower in cases that showed discordance between liver cell function and reticuloendothelial function compared with cases without such discordance, although reticuloendothelial function did not differ between discordant and nondiscordant groups. Liver cell function was better in cases of ALD than in cases of VLD, whereas reticuloendothelial function did not differ between the ALD group and the VLD group.

Adult↗
PubMed2000

[Genistein represses the induction of prostatic buds by testosterone] .

Genistein, a phytoestrogen and a kind of endocrine disrupters, inhibits tyrosine-specific protein kinase activity of the epidermal growth factor (EGF) receptor. It is also effective both in the suppression of the prostatic cell proliferation and the prostate carcinogenesis. We have recently demonstrated that several growth factors, like EGF, transforming growth factor-alpha (TGF-alpha), or keratinocyte growth factor (KGF), can induce prostatic bud formation in the absence of androgen. The present study was performed to investigate whether genistein can suppress testosterone-induced prostatic bud formation. Urogenital sinuses of 16.5-day male rat fetuses were cultured organotypically for 5 days in a serum-free medium containing 10 or 100 ng/ml genistein and 50 ng/ml testosterone. The number and total volume of prostatic buds were analyzed by laser scanning microscopy and computerized. We found that genistein inhibits significantly testosterone-induced prostatic bud formation. In the presence of genistein, cell proliferation of the sinus epithelium was suppressed and the number of prostatic buds and total volume of the buds were reduced as compared with those in the sinuses cultured with testosterone alone. Genistein did not appear to cause necrosis of the sinus. These results support our hypothesis that growth factors like EGF secreted from the sinus mesenchyme activated by testosterone are involved in the induction and stimulation of growth of the prostatic buds.

Androgen Antagonists↗
PubMed1999

Resistance to diet-induced obesity is associated with increased proopiomelanocortin mRNA and decreased neuropeptide Y mRNA in the hypothalamus.

Mechanisms mediating genetic susceptibility to diet-induced obesity have not been completely elucidated. Elevated hypothalamic neuropeptide Y (NPY) and decreased hypothalamic proopiomelanocortin (POMC) are thought to promote the development and maintenance of obesity. To assess the potential role of hypothalamic neuropeptide gene expression in diet-induced obesity, the present study examined effects of a high-fat diet on hypothalamic NPY and POMC mRNA in three strains of mice that differ in susceptibility to develop diet-induced obesity. C57BL/6J, CBA, and A/J mice were fed either normal rodent chow or a high-fat diet for 14 weeks after which hypothalamic gene expression was measured. On the high-fat diet, C57BL/6J mice gained the most weight, whereas A/J mice gained the least weight. On the high-fat diet, NPY mRNA significantly decreased as body weight increased in CBA and A/J mice, but not in C57BL/6J mice. In addition, POMC mRNA significantly increased as body weight increased in A/J mice, but not in CBA and C57BL/6J mice. Since decreased NPY mRNA and increased POMC mRNA would presumably attenuate weight gain, these results suggest that a high-fat diet produces compensatory changes in hypothalamic gene expression in mice resistant to diet-induced obesity but not in mice susceptible to diet-induced obesity.

Animals↗
PubMed1999

Neuronal adhesion molecule telencephalin induces rapid cell spreading of microglia.

Telencephalin (TLCN) is a neuronal surface glycoprotein whose expression is restricted to the telencephalon, the most rostral segment of the brain. TLCN binds to lymphocyte function-associated antigen-1 (LFA-1) integrin. In the central nervous system, LFA-1 is selectively and constitutively expressed by microglia, suggesting that TLCN/LFA-1 binding may mediate cell-cell interactions between telencephalic neurons and microglia. In the present study, we investigated the effects of recombinant TLCN protein on the morphology of microglia. TLCN induced an intensive spreading of lamellipodia, causing a rapid change in microglial morphology. In contrast, TLCN induced no significant change in morphology of neuroblastoma and fibroblasts. Furthermore, the TLCN-induced spreading of microglia was accompanied by a clustering of LFA-1 on cell surface membrane. These results provide evidence that TLCN binding to the surface of microglia transduces signals into microglia that mediate or accelerate cell spreading and LFA-1 redistribution, implying that neuronal TLCN may control the state and/or function of microglia in both physiological and pathological conditions.

Animals↗
PubMed1999

Identification and characterization of Drosophila homolog of Rho-kinase.

The Rho family of small GTPases and their associated regulators and targets are essential mediators of diverse morphogenetic events in development. Mammalian Rho-kinase/ROK alpha, one of the targets of Rho, has been shown to bind to Rho in GTP-bound form and to phosphorylate the myosin light chain (MLC) and the myosin-binding subunit (MBS) of myosin phosphatase, resulting in the activation of myosin. Thus, Rho-kinase/ROK alpha has been suggested to play essential roles in the formation of stress fibers and focal adhesions. We have identified the Drosophila homolog of Rho-kinase/ROK alpha, DRho-kinase, which has conserved the basic structural feature of Rho-kinase/ROK alpha consisting of the N-terminal kinase, central coiled-coil and C-terminal pleckstrin homology (PH) domains. A two-hybrid analysis demonstrated that DRho-kinase interacts with the GTP-bound form of the Drosophila Rho. Drho1, at the conserved Rho-binding site. DRho-kinase can phosphorylate MLC and MBS, preferable substrates for bovine Rho-kinase, in vitro. DRho-kinase is ubiquitously expressed throughout development, in a pattern essentially identical to that of Drho1. These results suggest that DRho-kinase is an effector of Drho1.

Amino Acid Sequence↗
PubMed1999

Sp3, but not Sp1, mediates the transcriptional activation of the p21/WAF1/Cip1 gene promoter by histone deacetylase inhibitor.

We previously reported that both sodium butyrate and trichostatin A (TSA), both of which are known as inhibitors of histone deacetylase, arrest human tumor cells at G1 and G2-M and activate the cyclin-dependent kinase inhibitor, the p21/WAF1/Cip1 gene promoter, through the Sp1 sites. In this study, we identified Sp1 and Sp3 as major factors binding to the Sp1 sites of the p21/WAF1/Cip1 promoter in MG63 cells through electrophoretic mobility shift assays and showed that TSA treatment did not change their binding activities. However, GAL4-Sp3 but not GAL4-Sp1 fusion protein supported the TSA-mediated gene induction from a luciferase reporter plasmid driven by five GAL4 DNA-binding sites. Moreover, the ectopic expression of dominant negative Sp3 repressed the enhancement by TSA of the p21/WAF1/Cip1 promoter and Sp1 site-driven promoter. Taken together, these results suggest that histone deacetylase inhibitor up-regulates p21/WAF1/Cip1 transcription by Sp3 but not by Sp1.

Cell Line↗
PubMed1999

Identification of the DNA binding surface of H-NS protein from Escherichia coli by heteronuclear NMR spectroscopy.

The DNA binding domain of H-NS protein was studied with various N-terminal deletion mutant proteins and identified by gel retardation assay and heteronuclear 2D- and 3D-NMR spectroscopies. It was shown from gel retardation assay that DNA binding affinity of the mutant proteins relative to that of native H-NS falls in the range from 1/6 to 1/25 for H-NS(60-137), H-NS(70-137) and H-NS(80-137), whereas it was much weaker for H-NS(91-137). Thus, the DNA binding domain was defined to be the region from residue A80 to the C-terminus. Sequential nuclear Overhauser effect (NOE) connectivities and those of medium ranges revealed that the region of residues Q60-R93 in mutant protein H-NS(60-137) forms a long stretch of disordered, flexible chain, and also showed that the structure of the C-terminal region (residues A95-Q137) in mutant H-NS(60-137) was nearly identical to that of H-NS(91-137). 1H and 15N chemical shift perturbations induced by complex formation of H-NS(60-137) with an oligonucleotide duplex 14-mer demonstrated that two loop regions, i.e. residues A80-K96 and T110-A117, play an essential role in DNA binding.

Amino Acid Sequence↗
PubMed1999

The cta3+ gene that encodes a cation-transporting P-type ATPase is induced by salt stress under control of the Wis1-Sty1 MAPKK-MAPK cascade in fission yeast.

In Schizosaccharomyces pombe, the Wis1-Sty1 MAP (mitogen-activated protein) kinase signaling cascade is known to play a major role in cellular adaptation to adverse external stimuli, including osmotic stress, oxidative stress, nutrient deprivation, DNA-damaging agents, and heat stress. Nonetheless, it is not known whether or not this particular MAPK cascade is also involved in response to the most common stress, salinity. In this study, we provide evidence that the Wis1-Sty1 MAP cascade is implicated in salt stress response through regulating expression of a salinity-inducible gene. The downstream target gene thus identified is the cta3+ gene, which encodes a cation-transporting P-type ATPase. The salt stress-responsive nature of cta3+ expression was characterized extensively. It was found that not only the Sty1 MAP kinase but also the Atf1 transcription factor is crucial for the inducible expression of cta3+. As far as we know, this is the first instance that the stress-activated Wis1-Sty1 MAPK cascade plays a role in salt stress response in S. pombe.

Adenosine Triphosphatases↗
PubMed1999

Cholesterol-dependent generation of a seeding amyloid beta-protein in cell culture.

Deposition of aggregated amyloid beta-protein (Abeta), a proteolytic cleavage product of the amyloid precursor protein (Abeta ), is a critical step in the development of Alzheimer's disease(Abeta++). However, we are far from understanding the molecular mechanisms underlying the initiation of Abeta polymerization in vivo. Here, we report that a seeding Abeta, which catalyzes the fibrillogenesis of soluble Abeta, is generated from the apically missorted amyloid precursor protein in cultured epithelial cells. Furthermore, the generation of this Abeta depends exclusively on the presence of cholesterol in the cells. Taken together with mass spectrometric analysis of this novel Abeta and our recent study (3), it is suggested that a conformationally altered form of Abeta, which acts as a "seed" for amyloid fibril formation, is generated in intracellular cholesterol-rich microdomains.

Amyloid beta-Peptides↗
PubMed1999

Tumor necrosis factor induces Bcl-2 and Bcl-x expression through NFkappaB activation in primary hippocampal neurons.

Emerging data indicate that tumor necrosis factor (TNF) exerts a neuroprotective effect in response to brain injury. Here we examined the mechanism of TNF in preventing neuronal death in primary hippocampal neurons. TNF protected neurons against hypoxia- or nitric oxide-induced injury, with an increase in the anti-apoptotic proteins Bcl-2 and Bcl-x as determined by Western blot and reverse transcriptase-polymerase chain reaction analysis. Treatment of neurons with an antisense oligonucleotide to bcl-2 mRNA or that to bcl-x mRNA blocked the up-regulation of Bcl-2 or Bcl-x expression, respectively, and partially inhibited the neuroprotective effect induced by TNF. Moreover, adenovirus-mediated overexpression of Bcl-2 significantly inhibited hypoxia- or nitric oxide-induced neuronal death. To examine the possible involvement of a transcription factor, NFkappaB, in the regulation of Bcl-2 and Bcl-x expression in TNF-treated neurons, an adenoviral vector capable of expressing a mutated form of IkappaB was used to infect neurons prior to TNF treatment. Expression of the mutant NFkappaB completely inhibited NFkappaB DNA binding activity and inhibited both TNF-induced up-regulation of Bcl-2 and Bcl-x expression and neuroprotective effect. These findings indicate that induction of Bcl-2 and Bcl-x expression through NFkappaB activation is involved in the neuroprotective action of TNF against hypoxia- or nitric oxide-induced injury.

Animals↗