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Biomedical subjects

H Sawada

Publications and source records attributed to H Sawada.

At least 235 records · Page 13Linked to original sources
PubMed1994

Effects of subacute administration of methamphetamine and nicotine on locomotor activity in transgenic mice expressing the human tyrosine hydroxylase gene.

We produced transgenic (Tg) mice carrying the human tyrosine hydroxylase (TH) gene. To investigate differences in the dopaminergic (DAergic) neuronal activity between the Tg and nTg mice, we examined changes in the locomotor activity induced by methamphetamine (MAP) and nicotine (NIC), which enhances DA release and induces TH enzyme activation, respectively. Surprisingly, however, the intensity of MAP (2.5 mg/kg, once a day for 14 days)-induced hyperlocomotion in the nTg mice was greater than that in the Tg mice, and, furthermore, the Tg mice were less sensitive to subacute administration of NIC (0.5 mg/kg, once a day for 14 days) than the nTg mice. These results suggest that DAergic neuronal function is suppressed in Tg mice to compensate for the overexpression of TH.

Animals↗
PubMed1994

Extramedullary tumor as presentation of leukemia: establishment of a new human GPIIb- and GPIIIa-positive leukemia cell line.

A 25-year-old man noted swelling of the right cervical lymph nodes in October 1983. Diagnosis of malignant lymphoma was made on the basis of pathological examination of biopsies. Despite both chemotherapy and irradiation treatment, blast cells appeared in the peripheral blood and bone marrow in April 1984. Immunophenotypic analysis demonstrated that the blasts in the patient's peripheral blood expressed CD13, CD33, CD41a, and no markers for T or B lymphocytes, suggesting that he had been suffering from megakaryocytic sarcoma. We established a new cell line derived from the blasts in the peripheral blood, designated KH184. KH184 cells expressed glycoprotein (GP) Ib (CD42b) and GPIIb/IIIa (CD41a), while platelet peroxidase (PPO) activity was negative in an ultrastructural study. Both Northern blot and flow cytometric analysis of surface antigens and DNA content revealed that treatment with 12-O-tetradecanoylphorbol 13-acetate (TPA) did not induce the maturation of these cells. Various cytokines such as interleukin 3 (IL-3), interleukin 6 (IL-6), and leukemia inhibitory factor (LIF) had no effect in promoting the growth of KH184 cells. KH184 cells expressing CD41a seem to possess unusual characteristics. KH184 cells, human GPIIb- and GPIIIa-positive leukemia cells, which lack response to TPA-induced differentiation, provide a new and unique model for the characterization of factors that are implicated in the terminal differentiation of megakaryocytes, and should aid in studies of the mechanism underlying the occurrence of megakaryocytic sarcoma.

Adult↗
PubMed1994

Kinetic studies on the plasminogen activation by the staphylokinase-plasmin complex.

A pure complex of staphylokinase and plasmin was prepared by affinity chromatography with lysine-Sepharose, which enabled the simple analysis of the mechanism of plasminogen activation by staphylokinase. We used a truncated staphylokinase (SAK), which lacks the 10 amino acid residues at the NH2 terminal of native staphylokinase. The purity of this complex was confirmed by the native PAGE profile. Image analysis of the SDS-PAGE profile revealed that the molar ratio of plasmin and SAK in the complex was about 1:1. Using this SAK-plasmin complex, the kinetic parameters for the activation of Glu- or Lys-plasminogen were determined. The kinetic constant, kcat/Km, obtained when Lys-plasminogen was used as a substrate was approximately 10 times higher than that obtained when Glu-plasminogen was used. This plasminogen activation property of the SAK-plasmin complex was comparable to that of other plasminogen activators, such as streptokinase, urokinase, and tissue-type plasminogen activator (t-PA). This SAK-plasmin complex will simplify the elucidation of plasminogen activation by SAK. Through kinetic studies, the fibrin specificity and participation of plasminogen activator inhibitor will be clarified.

Fibrinolysin↗
PubMed1994

Type VI collagen in the rat testis: monoclonal antibody, isolation, and localization during development.

To investigate the components of the seminiferous tubule extracellular matrix (ST-ECM), monoclonal antibodies were raised against ST-ECM. One of these (15B6) recognized the nonreduced form of type VI collagen. With this antibody as a probe, type VI collagen was isolated from an SDS-urea extract of ST-ECM. It took a tetrameric form, and upon reduction dissociated into a major 140-kDa band and two bands at 190 and 210 kDa. Developmental changes in the distribution of type VI collagen were investigated by immunofluorescence microscopy. In 16-day rat embryos when myoid cells began to differentiate, type VI, collagen was seen in the urogenital mesentery, and it had begun to surround the gonad and, in some embryos, the seminiferous cords. In newborn rats, it was found throughout the extracellular spaces between the cords, being localized in the interstitium. In adults, however, it was confined to two parallel lines around the seminiferous tubules and to filamentous structures in the adventitia of vascular systems. Immunoelectron microscopy showed that this collagen was distributed in the interstitium independently from collagenous fibrils, but was excluded from the basal lamina of Sertoli cells. These observations indicate that type VI collagen is a major component of the ST-ECM and that it may be important in the organization of the matrix and in the differentiation of peritubular cells.

Aging↗
PubMed1994

Phylogenetic evidence for Sphingomonas and Rhizomonas as nonphotosynthetic members of the alpha-4 subclass of the Proteobacteria.

To clarify the taxonomic relationships of the genera Rhizomonas and Sphingomonas, the 16S rRNA sequence of Rhizomonas suberifaciens IFO 15211T (T = type strain) was determined. A phylogenetic analysis of aligned 16S rRNA gene sequences revealed that eight species of the genus Sphingomonas and R. suberifaciens are closely related to Erythrobacter longus and Porphyrobacter neustonensis and, therefore, belong in the alpha-4 subclass of the Proteobacteria. Within this subclass, Sphingomonas species and R. suberifaciens are phylogenetically interrelated and comprise several subgroups. Our findings show that the genus and species definitions of these organisms are in need of revision.

Bacteriochlorophylls↗
PubMed1994

Long-term use of FK 506 in living related liver transplantation.

FK 506 (Tacrolimus) was used with steroids to treat 61 pediatric patients who received living related partial liver transplantation. Fifty-two recipients survived and 9 died between 6 months and 3 years after transplantation. In the surviving patients, oral doses of Tacrolimus were tapered from 0.298 +/- 0.277 mg/kg daily at 1 month after transplantation to 0.078 +/- 0.054 at 24 months after transplantation. The 12 h trough levels of Tacrolimus were 12.6 +/- 7.1 ng/ml and 4.1 +/- 2.4 at 1 and 24 months after transplantation, respectively. The percentage of recipients free from steroids was 77%, 97%, and 94% at 6, 12, and 24 months after transplantation, respectively. Liver allograft rejection was encountered in seven recipients, five of whom were treated by steroid pulse therapy and a dose increase of Tacrolimus; the remaining two required OKT3. However, there was no episode of rejection that required retransplantation. Infectious complications encountered in 34 patients included 12 bacterial, 3 fungal, and 19 viral infections. Two recipients died one of fungal pneumonia and one of Epstein-Barr virus-associated lymphoproliferative disorder. Regarding adverse reactions of Tacrolimus, hypertension was observed in 28 patients, diabetes mellitus in 3, pancreatitis in 3, convulsion in 1, tremor in 12, itching in 5, and pigmentation in the oral mucosa in 2. Slightly increased values of creatinine were observed in most of the patients; however, an abnormal increase of serum of serum creatinine (> 1.0 mg/dl) was confined to the complicated cases. Improvement of somatic growth was observed in 21 patients (62%) and 13 (75%) at 12 and 24 months after transplantation, respectively. The long-term use of Tacrolimus is highly effective in terms of its immunosuppressive potential and reduced adverse reaction. Steady growth development can be expected in pediatric recipients free from steroids.

Adolescent↗
PubMed1994

Molecular basis of beta-thalassemia in Japan: heterogeneity and origins of mutations.

Characterization of beta-thalassemia mutations was attempted for 13 unrelated Japanese patients heterozygous for beta-thalassemia. We have systematically analyzed beta-thalassemia genes using polymerase-chain-reaction-related techniques; dot blot hybridization with oligonucleotide probes complementary to known mutations, restriction endonuclease assay and direct sequencing of amplified genomic DNA. Seven different mutations were detected. Six of them are an amber mutation in codon 90 (GAG to TAG), a four-base-pair deletion in codons 41 and 42 causing premature termination due to frameshift, a C-T substitution at position 654 of IVS-2, a G-A substitution at position 1 of IVS-2 and a C-G substitution at position 848 of IVS-2, leading to splicing defects, and an ocher mutation (GAA-TAA) in codon 121 causing a thalassemia intermedia phenotype with inclusion body formation in erythrocytes. A silent mutation (CTG-TTG) was also detected in codon 91 of the allele with the IVS-2 position 1 mutation. These mutations have been reported previously in the Japanese population. The other mutation is a novel one in the Japanese, an amber mutation (TGG-TAG) in codon 15, causing a beta zero-thalassemia phenotype by premature termination of the beta-globin chain synthesis. We analyzed haplotypes of chromosomes bearing each beta-thalassemia mutation. Origins and a spectrum of mutations in comparison with those detected in malaria-endemic regions are discussed.

Adolescent↗
PubMed1994

Structure-depolarizing activity relationship for achatin-I, a tetrapeptide with a D-Phe residue, and its derivatives toward the crayfish giant axon.

Achatin-I (Gly-D-Phe-Ala-Asp) is a tetrapeptide isolated from the ganglia of an African giant snail (Achatina fulica Férussac). The compound and its derivatives were synthesized, and their effects on the action potential of the crayfish giant axon elicited by electrical stimulation were examined by an intracellular recording method. The membrane potential after the action potential had fallen was elevated by some compounds at an acidic but not neutral pH level. An analysis of the structure-activity relationship for the activity to elevate the afterpotential at an acidic pH level, suggests that the factors favorable for activity were the beta-turn conformation, a beta- or gamma-carboxyl group in the C-terminal residue, appropriate hydrophobicity and/or bulkiness in the protecting groups for the alpha-amino group at the N-terminus, and the number of negative charges in the entire molecule.

Action Potentials↗
PubMed1994

Identification of ommin in the integument of the silkworm, Bombyx mori.

An ommin was isolated from the integument of the quail mutant of the silkworm, Bombyx mori, using column chromatography on SP-Sephadex and cellulose powder. As a standard, ommin was isolated from diapause eggs of the normal silkworm. The red pigment from the larval integument of quail mutants was identical to the standard compound with respect to absorption spectrum, infrared spectrum and RF values in thin-layer chromatography (TLC). After acid hydrolysis of the pigment, 3-hydroxykynurenine was detected by TLC. This is the first report of an ommin in a lepidopteran larval integument.

Animals↗
PubMed1994

Inhibition of erythroid differentiation by stem cell factor in K562 cells expressing the c-kit gene.

We found a K562 subclone (K562YO) that highly expressed the c-kit gene. K562YO had a higher capability of erythroid differentiation by hemin and cytosine arabinoside (Ara-C) than its parent K562 (KIT-). We obtained the transfectant expressing c-kit by introducing c-kit cDNA into K562 (KIT-). The differentiation of the transfectant was similar to that of the parent cell. Thus the difference described above was not due to the expression of c-kit. Next, we investigated the effects of stem cell factor (SCF) on the differentiation of the K562 cell expressing c-kit. SCF did not enhance the cell growth of K562YO. On the other hand, SCF suppressed induction of benzidine-positive cells when c-kit-positive cells were treated with hemin and Ara-C, especially at a low concentration. Furthermore, c-kit mRNA and protein were down-regulated during erythroid differentiation. SCF also downregulated the c-kit proteins. Our results suggest that the SCF/c-kit signals could act negatively for erythroid differentiation of the K562 cells expressing c-kit. K562YO is also useful for studying the mechanism that controls the expression of the c-kit gene because there is a K562 counterpart cell line that does not express this gene.

Blotting, Northern↗
PubMed1994

Use of nanogold followed by silver enhancement and gold toning for preembedding immunolocalization in osmium-fixed, Epon-embedded tissues.

A reliable, sensitive, high-resolution method with good structural visualization for preembedding immunoelectron microscopy was proposed. The present technique involves the following processes. Immunolabeling of cryostat sections with primary antibodies and with nanogolds, silver intensification for visualization of nanogold secondary antibodies, gold-toning for stabilization of silver shells, and osmium postfixation and embedding in Epon for good structural visualization. The technique was applied to rat testis with anti-laminin and anti-fibronectin antibodies, showing that these two proteins are localized differentially in the lamina propria of the tissue.

Animals↗
PubMed1994

Human mast cells produce type VIII collagen in vivo.

Mast cells are assuming importance not only in their familiar role in acute allergic and parasitic diseases but also in chronic inflammatory, immunologic and fibrotic states. The processes by which human extracellular matrices are influenced by mast cells have remained obscure. We report here the production of type VIII collagen by human mast cells. Mast cells representing each of the known phenotypes were identified in a variety of tissues using histochemical techniques, and monoclonal antibodies specific for tryptase, chymase, and c-kit. Mast cells in normal and pathologic tissues expressed type VIII collagen alpha-1 chain protein and mRNA, detected by immunohistochemistry using monoclonal and polyclonal antibodies, and non-isotopic oligonucleotide in situ hybridization using digoxigenin-labelled oligonucleotide probes based on the published human alpha-1 collagen VIII sequence. Perivascular location of type VIII collagen positive mast cells was a striking finding. The secretion of type VIII collagen by mast cells in vivo may contribute to angiogenesis, tissue remodelling, and fibrosis.

Base Sequence↗
PubMed1994

[Clinical experience and early results of aortic valve replacements with Medtronic Hall 20 A].

We experienced aortic valve replacement for 18 patients (4 male and 14 female, ranging from 40 to 81 years old, mean 64 years old) with small aortic annulus with new small prosthesis. Medtronic Hall 20 A (MH 20 A). The average body surface area was 1.47 m2 (range 1.28 to 1.81 m2). One patient was died of lung cancer at 3 months postoperatively. One nonstructural dysfunction and one low cardiac output syndrome was noted during operation. Sixteen survivors with MH 20 A, showed satisfactory clinical results, except for minor thromboembolism, in 2 patients. The MH 20 A had the same function as that of MH 21 A, already reported. We concluded that aortic valve replacement by Medtronic Hall 20 A prosthesis was usefull for the patient with small aortic annulus.

Adult↗
PubMed1994

[123I-MIBG scintigraphy in patients with neuroblastoma].

123I-meta-iodobenzylguanidine (123I-MIBG) scintigraphy was performed in 9 patients who were suspected to have a neuroblastoma. Positive images were obtained in 4 patients who had a neuroblastoma. Negative images were obtained in 5 patients who did not have a neuroblastoma. 123I-MIBG scan revealed an active tumor in a patient who had received intensive chemotherapy for the recurrence of neuroblastoma with returning of all tumor markers including neuron specific enolase to normal range. This indicated that 123I-MIBG scan can be used to assess the effect of therapy.

3-Iodobenzylguanidine↗
PubMed1994

Selective inhibition of human immunodeficiency virus type 1 replication by novel fluoroalkylated oligomers in vitro.

Several fluoroalkylated oligomers were found to be potent and selective inhibitors of human immunodeficiency virus type 1 (HIV-1) in vitro. Among the test compounds, bis(perfluoro-1,4,7,10-tetramethyl-2,5,8,11-tetraoxatetradecyl+ ++)methacrylic acid oligomer (MAA-HFPO5) emerged as the most potent inhibitor of HIV-1 replication. Its 50% antivirally effective concentration for the IIIB strain was 2.8 mu g/ml, whereas the compound did not affect the growth and viability of mock-infected MT-4 cells at concentrations < or = 100 micrograms/ml. MAA-HFPO5 was also inhibitory to other strains of HIV-1 in various human T-cell systems, including peripheral blood lymphocytes. MAA-HFPO5 inhibited syncytium formation and virus adsorption. The combination of MAA-HFPO5 with either 3'-azido-3'dioxythymidine or dextran sulfate resulted in an additive effect. Thus, fluoroalkylated oligomers are novel HIV-1 inhibitors that warrant further evaluation of their therapeutic potential.

Adsorption↗
PubMed1993

Different ratios in 20 S proteasomes and regulatory subunit complexes in two isoforms of the 26 S proteasome purified from rabbit skeletal muscle.

A ubiquitin/ATP-dependent proteinase complex (26 S proteasome) was highly purified from rabbit skeletal muscle. The purified 26 S proteasome easily dissociated into a 20 S proteasome and a regulatory subunit complex on non-denaturing PAGE. By using cleavable and non-cleavable cross-linkers, it was revealed that the 26 S proteasome exists in two isoforms: one (D complex) consists of the 20 S proteasome and the regulatory subunit complex in the ratio of one to two, while the other (C complex) exists in an equal molar ratio. Molecular masses of the former and the latter isoforms were estimated to be 1,700 kDa and 1,400 kDa, respectively, by gel filtration, and 2,400 kDa and 1,400 kDa, respectively, by Ferguson plot analysis. Furthermore, both isoforms efficiently hydrolyzed Suc-Leu-Leu-Val-Tyr-MCA and ubiquitin-conjugated [125I]lysozyme. These results suggest that the D and C complexes are active proteinase complexes, most probably corresponding to the dumbbell-like and mushroom-like (or space capsule-like) molecules, respectively.

Amino Acid Sequence↗