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Biomedical subjects

H Sawada

Publications and source records attributed to H Sawada.

At least 55 records · Page 3Linked to original sources
PubMed2001

[Persistent hyperplastic primary vitreous--a case report of adult onset acute angle-closure glaucoma].

BACKGROUND: We report a patient with persistent hyperplastic primary vitreous(PHPV) who presented with acute angle-closure glaucoma in his adult life. CASE: A 30-year-old man had an attack of acute angle-closure glaucoma associated with retrolenticular fibrous tissue, atrophic retina, and elongated cilliary process in his right eye. RESULT: Ultrasound biomicroscopy(UBM) study showed iris bowing, shallow anterior chamber, and elongated cilliary body which were being pulled by the retrolenticular mass. The posterior chamber was normal. CONCLUSION: Although the mechanisms of secondary angle-closure glaucoma in PHPV are complicated, we suspected pupillary block resulting from constriction by the retrolenticular mass in this case.

Acute Disease↗
PubMed2000

27 kDa extracellular matrix protein revealed by a monoclonal antibody raised against rat testis.

In search of unique components of the seminiferous tubule extracellular matrix, monoclonal antibodies were raised against an isolated seminiferous tubule extracellular matrix, and the monoclonal antibody 12G11 was cloned. By immunofluorescence microscopy in eight kinds of rat tissues (testis, lung, liver, small intestine, cardiac muscle, skeletal muscle, kidney, and brain), 12G11 antigen existed only in the testis. Immunoelectron microscopy revealed that the antigen is localized in the basement membrane of the seminiferous tubule and in the basement membranes of myoid cells. For a biochemical analysis, eight kinds of rat extracellular matrices were isolated and solubilized with 8 M urea and 2% beta-mercaptoethanol. Immunoblot analysis of these samples in 0.8% agarose gel also showed that the antigen was specific for the testis, and in a two high-molecular weight aggregates. These aggregates seemed to contain type IV collagen and laminin chains. The antigen of 12G11 antibody was shown to be 27 kDa by 10% SDS-PAGE followed by immunoblotting. From these data, the existence of a testis specific 27 kDa basement membrane protein, which associate with type IV collagen and laminin, was suggested.

Animals↗
PubMed2000

Activation of human peroxisome proliferator-activated receptor (PPAR) subtypes by pioglitazone.

Pioglitazone, a thiazolidinedione (TZD) derivative, is an antidiabetic agent that improves hyperglycaemia and hyperlipidaemia in obese and diabetic animals via a reduction in hepatic and peripheral insulin resistance. The TZDs including pioglitazone have been identified as high affinity ligands for peroxisome proliferator-activated receptor (PPAR) gamma. The selectivity of pioglitazone for the human PPAR subtypes has not been reported, thus, we investigated the effect of pioglitazone on the human PPAR subtypes. Transient transactivation assay showed that pioglitazone is a selective hPPARgamma1 activator and a weak hPPARalpha activator. Binding assay indicated that the transactivation of hPPARgamma1 or hPPARalpha by pioglitazone is due to direct binding of pioglitazone to each subtype. Furthermore, pioglitazone significantly increased the apoA-I secretion from the human hepatoma cell line HepG2.

Animals↗
PubMed2000

Protection of cultured spinal motor neurons by estradiol.

Estrogens have been reported to exert neuroprotection in the brain, but there have been no reports of such neuroprotection in spinal motor neurons, the neurons selectively involved in amyotrophic lateral sclerosis (ALS). In this study, we demonstrated that 17beta-estradiol and its biologically inactive stereoisomer, 17alpha-estradiol, prevented glutamate- and nitric oxide (NO)-induced selective motor neuronal death observed in primary cultures of the rat spinal cord. The dose of estradiols required for motor neuron protection was greatly reduced by co-administration with glutathione. The results of this study shows that estradiol protects spinal motor neurons from excitotoxic insults in vitro, and may have application as a treatment for ALS.

Animals↗
PubMed2000

Ultrastructure of the capillary pericytes and the expression of smooth muscle alpha-actin and desmin in the snake infrared sensory organs.

The infrared sensory membranes of pit organs of pit vipers have an extremely rich capillary vasculature that forms many vascular loops, each serving a small number of infrared nerve terminals. We clarified the ultrastructure of capillary pericytes in the pit membranes by scanning and transmission electron microscopy, and examined the immunoreactivity in their cytoplasm to two contractile proteins: smooth muscle alpha-actin (SM alpha-actin) and desmin. The capillary pericytes had two major cytoplasmic processes: thickened primary processes that radiate to embrace the endothelial tube and flattened secondary processes that are distributed widely on the endothelium. Coexpression of SM alpha-actin and desmin was observed in the pericytes of entire capillary segments, and SM alpha-actin was characterized by prominent filament bundles directed mainly at right angles to the capillary long axis. This expression pattern was different from that of capillary pericytes of the scales, where SM alpha-actin was expressed diffusely in the cytoplasm. In a series of electron microscopic sections, we often observed the pericyte processes depressing the endothelial wall. We also observed a close relationship of the pericytes with inter-endothelial cell junctions, and pericyte processes connected with the endothelial cells via gap junctions. From these findings, we surmised that capillary pericytes in the pit membrane have a close functional relationship with the endothelium, and through their contractile and relaxing activity regulate capillary bloodflow to stabilize production of infrared nerve impulses.

Actins↗
PubMed2000

Characterization of the human NTAK gene structure and distribution of the isoforms for rat NTAK mRNA.

NTAK (neural- and thymus-derived activator for the ErbB kinase, neuregulin-2) is a novel member of the epidermal growth factor (EGF) family. We have isolated and characterized the human NTAK gene, comprising 12 exons spanning in excess of 55 kilobases (kb). The 7. 0kb long mRNA of the human NTAK gene was expressed in the human neuroblastoma SK-N-SH cell line with two alternative isoforms detected. Furthermore, six isoforms have been identified from rat brain and PC-12 cells. Although the alpha isoform of the NTAK gene was found to be expressed in all tissues including brain, the beta isoform was expressed only in rat brain tissues. Potential regulatory regions included consensus binding sites for AP-2, TF-IIIA, Sp-1, and YY-1 located in the 5'-flanking region of the NTAK gene.

Amino Acid Sequence↗
PubMed2000

The Effect of Intraocular Lidocaine in White Rabbit Eyes.

Purpose: Recently, intraocular lidocaine anesthesia has been used in cataract surgery. We studied the toxicity of intraocular unpreserved lidocaine for corneal endothelial cell and retina using Japanese white rabbits.Methods: The rabbits were divided into two groups. One group was injected intracamerally and the other was injected intravitreally with 0.2 ml of unpreserved lidocaine of 0%, 0.02%, 0.2%, or 2% concentration. The number of corneal endothelial cells was measured 1 week after the injection. After measurements, the rabbit corneas were studied histologically. The retina was examined by electroretinogram prior to initial injection through 1 week after the injection.Results: There was no significant change in number of corneal endothelial cells after injection of 0.2% lidocaine. However, histological abnormality was seen in corneal endothelial cells after 2% lidocaine injection. There was also significant change in electroretinogram with 2% lidocaine injection. No histological abnormality was seen in the retina 1 week after the injection.Conclusion: The rabbit cornea and retina manifested no serious changes after the injection of lidocaine at less than 0.2% concentration functionally and histologically.

Journal Article↗
PubMed2000

Accumulation of human alpha-synuclein in different cytoskeletons in Lewy bodies in brains of dementia with Lewy bodies.

We investigated the origin of alpha-synuclein-immunoreactive components in Lewy bodies (LB) in brains of dementia with Lewy bodies (DLB) using immunohistochemistry and immunoelectron microscopy with anti-alpha-synuclein antibodies and anti-cytoskeleton antibodies. alpha-Synuclein-positive LB light microscopically consisted of phosphorylated neurofilament (PN)-positive LB, tubulin-positive LB and LB that were negative for both stains. Immunoelectron microscopically, PN-positive LB were composed of PN-positive and alpha-synuclein-positive filamentous components, suggesting that these filamentous components originate from neurofilaments with partially reduced immunoreactivity and alpha-synuclein accumulation. However, tubulin-positive LB were composed of tubulin-positive and alpha-synuclein-positive tubular components, suggesting that these tubular components originate from microtubules with diffusely reduced immunoreactivity and alpha-synuclein accumulation. The results of the present study suggest that alpha-synuclein accumulates in different cytoskeletons in the LB in DLB brains presumably due to a blockage of axonal transport.

Aged↗
PubMed2000

Neuroprotective effect of cyclic GMP against radical-induced toxicity in cultured spinal motor neurons.

We have previously reported that nitric oxide-related cyclic guanosine-3',5'-monophosphate (GMP) protected spinal nonmotor neurons, but not motor neurons against chronic glutamate-induced toxicity, which is associated with selective motor neuronal death after glutamate stress. In this report, we investigated the effect of cyclic GMP against reactive oxygen species (ROS)-induced toxicity in cultured neurons from embryonic rat spinal cords. Pretreatment with a cGMP analogue, 8-bromoguanosine monophosphate (8br-cGMP), for 12-24 hours protected both spinal motor neurons and nonmotor neurons against injury induced by either hydrogen peroxide (H(2)O(2)), or a glutathione depletor, L-buthionine-[S,R]-sulfoximine (BSO). This protective effect was reversed by coadministration with the cGMP-dependent protein kinase (PKG) inhibitor Arg-Lys-Arg-Ala-Arg-Lys-Glu. Interestingly, when cultures were exposed to BSO for 24 hours to allow irreversible inhibition of glutathione synthesis, 8br-cGMP protected only nonmotor neurons. Our results indicate that cGMP attenuates oxidative injury to cultured spinal neurons, in a mechanism associated with glutathione synthesis.

Animals↗
PubMed2000

Tumor metastasis-associated human MTA1 gene: its deduced protein sequence, localization, and association with breast cancer cell proliferation using antisense phosphorothioate oligonucleotides.

Using differential cDNA library screening techniques based on metastatic and nonmetastatic rat mammary adenocarcinoma cell lines we previously cloned and sequenced the metastasis-associated gene mta1. Using homology to the rat MTA1 gene we cloned the human MTA1 gene and found it to be overexpressed in a variety of human cell lines. We found a close similarity between the human MTA1 and rat MTA1 genes, as shown by 88% and 96% identities of the nucleotide and predicted amino acid sequences, respectively. Both genes encode novel proteins that contain a proline-rich region (SH3 binding motif), a putative zinc finger motif, a leucine zipper motif, and five copies of the SPXX motif often found in gene regulatory proteins. Using Southern blot analysis, the MTA1 gene was found to be highly conserved among all species examined; and using Northern blot analysis, MTA1 transcripts were found in virtually all cell lines of human origin that were analyzed, including melanoma and breast, cervix and ovarian carcinoma cells and normal breast epithelial cells. However, the expression level of the MTA1 gene in a normal breast epithelial cell was approximately 50% of that found in rapidly growing breast adenocarcinoma cell lines and an atypical mammary cell line. Experimental inhibition of MTA1 protein expression using antisense phosphorothioate oligonucleotides resulted in growth inhibition of human MDA-MB-231 breast cancer cells with relatively high expression of the MTA1 gene. Furthermore, the MTA1 protein was localized in the nuclei of cells transfected using a mammalian expression vector containing the full-length MTA1 gene. The results suggest that the MTA1 protein may function in cellular signaling processes important in the progression and growth of cancer cells, possibly as a nuclear regulatory factor.

Amino Acid Sequence↗
PubMed2000

Comparison of separation behavior of benzodiazepines in packed capillary electrochromatography and open-tubular capillary electrochromatography.

Packed column capillary electrochromatography (CEC), open-tubular CEC and microcolum liquid chromatography (LC) using a cholesteryl silica bonded phase have been studied to compare the retention behavior for benzodiazepines. It has been found that packed column CEC gives better resolution, faster analysis time than microcolumn LC for benzodiazepines maintaining similar selectivity except for some solutes which are charged species under the separation conditions. However, open-tubular CEC gave different selectivities to a larger extent for charged benzodiazepines from that which should be produced by the chromatographic properties of the cholesteryl silica phase. Charged species migration times are mainly influenced by electrophoretic mobility rather than the chromatographic interactions.

Benzodiazepines↗
PubMed2000

Involvement of 14-3-3 proteins in nuclear localization of telomerase.

Maintenance of telomeres is implicated in chromosome stabilization and cell immortalization. Telomerase, which catalyzes de novo synthesis of telomeres, is activated in germ cells and most cancers. Telomerase activity is regulated by gene expression for its catalytic subunit, TERT, whereas several lines of evidence have suggested a post-translational regulation of telomerase activity. Here we identify the 14-3-3 signaling proteins as human TERT (hTERT)-binding partners. A dominant-negative 14-3-3 redistributed hTERT, which was normally predominant in the nucleus, into the cytoplasm. Consistent with this observation, hTERT-3A, a mutant that could not bind 14-3-3, was localized into the cytoplasm. Leptomycin B, an inhibitor of CRM1/exportin 1-mediated nuclear export, or disruption of a nuclear export signal (NES)-like motif located just upstream of the 14-3-3 binding site in hTERT impaired the cytoplasmic localization of hTERT. Compared with wild-type hTERT, hTERT-3A increased its association with CRM1. 14-3-3 binding was not required for telomerase activity either in vitro or in cell extracts. These observations suggest that 14-3-3 enhances nuclear localization of TERT by inhibiting the CRM1 binding to the TERT NES-like motif.

14-3-3 Proteins↗
PubMed2000

Discovery of novel, potent, and selective small-molecule CCR5 antagonists as anti-HIV-1 agents: synthesis and biological evaluation of anilide derivatives with a quaternary ammonium moiety.

The search for new small-molecule CCR5 antagonists by high-throughput screening (HTS) of the Takeda chemical library using [(125)I]RANTES and CHO/CCR5 cells led to the discovery of lead compounds (A, B) with a quaternary ammonium or phosphonium moiety, which were synthesized to investigate new MCP-1 receptor antagonists. A series of novel anilide derivatives 1 with a quaternary ammonium moiety were designed, synthesized, and tested for their CCR5 antagonistic activity. Through the optimization of lead compounds, we have found N,N-dimethyl-N-[4-[[[2-(4-methylphenyl)-6, 7-dihydro-5H-benzocyclohepten-8-yl]carbonyl]amino]benzyl]tetrahydr o-2 H-pyran-4-aminium chloride (1r, TAK-779) as a highly potent and selective nonpeptide CCR5 antagonist with a IC(50) value of 1.4 nM in the binding assay. Compound 1r also inhibited the replication of macrophage (M)-tropic HIV-1 (Ba-L strain) in both MAGI-CCR5 cells and PBMCs with EC(50) values of 1.2 and 3.7 nM, respectively. The synthesis and structure-activity relationships of 1r and its related compounds are detailed.

Amides↗
PubMed2000

Phosphatidylinositol 3-kinase mediates neuroprotection by estrogen in cultured cortical neurons.

It has been shown that estrogen replacement in menopausal women is effective in slowing down the progression of cognitive impairment in Alzheimer's disease. Although recent studies have demonstrated the neuroprotective effects of estrogen, the precise mechanism of neuroprotection has not been elucidated. In the present study, we show that the phosphatidylinositol 3-kinase (PI3-K) cascade is involved in the neuroprotective mechanism stimulated by estrogen. Exposure to glutamate reduced the viability of rat primary cortical neurons. Pretreatment with 10 nM 17beta-estradiol significantly attenuated the glutamate-induced toxicity. This neuroprotective effect of 17beta-estradiol was blocked by co-administration with LY294002, a selective PI3-K inhibitor, but not by co-administration with PD98059, a selective mitogen activated protein kinase kinase inhibitor. Pretreatment with ICI182780, a specific estrogen receptor antagonist, also blocked the neuroprotection. Immunoblotting assay revealed that treatment with 17beta-estradiol induced the phosphorylation of Akt/PKB, an effector immediately downstream of PI3-K. These results suggest that PI3-K mediates the neuroprotective effect of 17beta-estradiol against glutamate-induced neurotoxicity.

Animals↗
PubMed2000

Modest neuropsychological deficits caused by reduced noradrenaline metabolism in mice heterozygous for a mutated tyrosine hydroxylase gene.

Tyrosine hydroxylase (TH) is the initial and rate-limiting enzyme for the biosynthesis of catecholamines that are considered to be involved in a variety of neuropsychiatric functions. Here, we report behavioral and neuropsychological deficits in mice carrying a single mutated allele of the TH gene in which TH activity in tissues is reduced to approximately 40% of the wild-type activity. In the mice heterozygous for the TH mutation, noradrenaline accumulation in brain regions was moderately decreased to 73-80% of the wild-type value. Measurement of extracellular noradrenaline level in the frontal cortex by the microdialysis technique showed a reduction in high K(+)-evoked noradrenaline release in the mutants. The mutant mice displayed impairment in the water-finding task associated with latent learning performance. They also exhibited mild impairment in long-term memory formation in three distinct forms of associative learning, including active avoidance, cued fear conditioning, and conditioned taste aversion. These deficits were restored by the drug-induced stimulation of noradrenergic activity. In contrast, the spatial learning and hippocampal long-term potentiation were normal in the mutants. These results provide genetic evidence that the central noradrenaline system plays an important role in memory formation, particularly in the long-term memory of conditioned learning.

Animals↗
PubMed2000

Isolation and characterization of a novel 530-kDa protein complex (PC530) capable of associating with the 20S proteasome from starfish oocytes.

A novel protein complex called PC530 was purified concomitantly with proteasomes from oocytes of the starfish, Asterina pectinifera, by chromatography with DEAE-cellulose, phosphocellulose, Mono Q, and Superose 6 columns. The molecular mass of this complex was estimated to be 530 kDa by Ferguson plot analysis and about 500 kDa by Superose 6 gel filtration. Since the 1500-kDa proteasome fractions contain the PC530 subunits as well as the 20S proteasomal subunits, and also since the purified PC530 and the 20S proteasome were cross-linked with a bifunctional cross-linking reagent, it is thought that PC530 is able to associate with the 20S proteasome. The PC530 comprises six main subunits with molecular masses of 105, 70, 50, 34, 30, and 23 kDa. The 70-kDa subunit showed a sequence similarity to the S3/p58/Sun2/Rpn3p subunit of the 26S proteasome, whereas the other subunits showed little or no appreciable similarity to the mammalian and yeast regulatory subunits. These results indicate that starfish oocytes contain a novel 530-kDa protein complex capable of associating with the 20S proteasome, which is distinctly different from PA700 or the 19S regulatory complex in molecular size and subunit composition.

Amino Acid Sequence↗