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S Kojima

Publications and source records attributed to S Kojima.

At least 19 recordsLinked to original sources
PubMed1992

Isolation and partial characterization of SSI-like protease inhibitors from Streptomyces.

We attempted to screen a series of Streptomyces subtilisin inhibitor-like (SIL) proteins among several Streptomyces strains by using a highly sensitive assay system established by us. Of six randomly tested strains, four were found to produce SIL inhibitors as their major secreted proteins, suggesting that they might be distributed in a high frequency among this genus. Three inhibitors exhibited inhibition of both subtilisin BPN' and trypsin. Comparison of the amino terminal sequences of these isolated proteins with those of other reported SIL inhibitors revealed that the beta 1- and beta 2-sheets in SSI were highly conserved.

Amino Acid Sequence↗
PubMed1992

Investigation into the 5-hydroxytryptamine-induced relaxation of the circular smooth muscle of guinea-pig stomach fundus.

The 5-HT receptor that mediates relaxation of circular muscle strips of the guinea-pig stomach fundus under resting tone was investigated. Concentration-dependent relaxation was obtained in the presence of atropine (0.2 microM) with 5-hydroxytryptamine (5-HT) (apparent mean pEC50 value, 5.27), 5-carboxamidotryptamine (7.35), 5-methoxytryptamine (4.98) and 5-methyltryptamine (4.58). 1-(m-Trifluoromethyl-phenyl)piperazine and 8-hydroxy-2-(di-n- propylamino)tetralin acted as partial agonists while 2-methyl-5-hydroxytryptamine, alpha-methyl-5-hydroxytryptamine, sumatriptan, metoclopramide and cisapride had little or no effect on the guinea-pig stomach fundus. The concentration-response curve for 5-HT was not affected by tetrodotoxin (0.3 microM), guanethidine (5 microM) or indomethacin (2 microM), suggesting that the relaxation is non-neuronal in origin and is independent of the release of catecholamines or prostanoids. The non-selective 5-HT receptor antagonist, metitepine (0.03-0.1 microM), the 5-HT1C/5-HT2 receptor antagonists, mianserin (0.3-1 microM), pizotifen (0.3-1 microM), ketanserin (3-10 microM), and the 5-HT1A/5-HT2 receptor antagonist, spiperone (3 microM), shifted the concentration-response curves for 5-HT to the right. A 5-HT3 receptor antagonist, ICS205-930 (1 microM), propranolol (1 microM) and phentolamine (1 microM) failed to block the 5-HT-induced relaxation. In conclusion, the results found with agonists and antagonists are compatible with the view that a 5-HT1-like receptor is involved in 5-HT-induced direct relaxation of circular muscle of guinea-pig stomach fundus.

Animals↗
PubMed1992

Prolonged circulation time in vivo of large unilamellar liposomes composed of distearoyl phosphatidylcholine and cholesterol containing amphipathic poly(ethylene glycol).

The effect of poly(ethylene glycol) (PEG) on the circulation time of liposomes in mice was examined by employing amphipathic PEGs (phosphatidylethanolamine (PE) derivatives of PEG) with average molecular weights of 1000, 2000, 5000 and 12,000. The activity of dioleoyl phosphatidylethanolamine-PEG (DOPE-PEG) in prolonging the circulation time of egg phosphatidylcholine/cholesterol large unilamellar liposomes (ePC/CH LUVs) (200 nm) was proportional to the molecular weight of PEG, i.e., 12000 = 5000 greater than 2000 greater than 1000. On the other hand, inclusion of distearoylphosphatidylethanolamine-PEG (DSPE-PEG) or dipalmitoyl-phosphatidylethanolamine-PEG (DPPE-PEG) of low molecular weight such as 1000 and 2000 in distearoylphosphatidylcholine (DSPC)/CH LUVs or dipalmitoyl phosphatidylcholine (DPPC)/CH LUVs effectively increased their blood circulation time. At least 3 mol% of amphipathic PEG in liposomes was required for activity. Addition of CH, which has a bilayer-tightening effect, to DSPC/CH/DSPE-PEG2000 LUVs further increased the blood residence time. A size of less than 300 nm was essential for prolonging the residence time of amphipathic PEG-containing liposomes in blood. DSPC/CH/DSPE-PEG2000 LUVs (1:1:0.13, m/m) containing 6 mol% of PEG and 200 nm in diameter remained in the circulation for over 24 h after injection and may be clinically useful for sustained release of an entrapped drug in the bloodstream and for drug accumulation in solid tumors.

Animals↗
PubMed1992

Molecular cloning of a Drosophila diacylglycerol kinase gene that is expressed in the nervous system and muscle.

We have isolated a Drosophila melanogaster diacylglycerol kinase (DGK, EC 2.7.1.107) homologue by using a porcine DGK cDNA probe and we have characterized its structure and expression. The DGK cDNA has a single open reading frame that encodes 791 amino acids. The Drosophila and porcine DGKs share a similar carboxyl-terminal region, a putative catalytic domain, which is divided into two separate domains in Drosophila. The DGK gene was mapped to the cytogenetic position 43F1, and its DGK mRNA is abundant both in embryo and in adult fly. By in situ hybridization to sections of adult flies, we demonstrated that the mRNA is present predominantly in the nervous system and muscles, including compound eyes, brain cortex, fibrillar muscle, and tubular muscle. In a 10- to 11-hr embryo, the DGK gene is expressed abundantly in a limited number of cells in the procephalic region and in the ventral nerve cord. The pattern of temporal and spatial expression suggests that the DGK protein has an important function in the adult nervous system and muscle and during the development of the embryonic nervous system.

Amino Acid Sequence↗
PubMed1992

Neopterin as an endogenous antioxidant.

The in vitro potency of neopterin (NP) as an antioxidant and its in vivo activity to suppress alloxan-induced diabetes were investigated. The reduced form of neopterin, 5,6,7,8-tetrahydroneopterin (NPH-4), showed an extremely high superoxide anion radical scavenging activity in two assay systems, i.e. xanthine/xanthine oxidase- and macrophage/phorbol myristate acetate (PMA)-reaction systems. NPH-4 also inhibited the oxidation of linoleic acid about as effectively as uric acid. Furthermore, NPH-4 and NP effectively suppressed alloxan-induced mouse diabetes. These results suggest that pteridines play an important role as endogenous antioxidants.

Alloxan↗
PubMed1992

Two-way cleavage of beta-amyloid protein precursor by multicatalytic proteinase.

The beta-amyloid protein (beta-AP) derived from a beta-amyloid protein precursor (APP) is a hallmark of Alzheimer's disease. The abundant generation of beta-AP suggests the abnormal processing of APP, but the molecular mechanism remains unclear. The main APP-processing enzyme was purified from the rat brain and identified to be a macropain-like multicatalytic proteinase. The purified enzyme cleaved the Gln15-Lys16 bond of beta-AP, but altered to cleave at the N-terminus of beta-AP to release the extracellular domain of beta-AP in the presence of Ca2+. These findings suggest that the functional change in this multicatalytic proteinase may result in abnormal processing of APP.

Amino Acid Sequence↗
PubMed1992

Crystal structure of an engineered subtilisin inhibitor complexed with bovine trypsin.

Proteinase specificity of a proteinaceous inhibitor of subtilisin (SSI; Streptomyces subtilisin inhibitor) can be altered so as to strongly inhibit trypsin simply by replacing P1 methionine with lysine (with or without concomitant change of the P4 residue) through site-directed mutagenesis. Now the crystal structure of one such engineered SSI (P1 methionine converted to lysine and P4 methionine converted to glycine) complexed with bovine trypsin has been solved at 2.6 A resolution and refined to a crystallographic R factor of 0.173. Comparing this structure with the previously established structure of the native SSI complexed with subtilisin BPN', it was found that (i) P1 lysine of the mutant SSI is accommodated in the S1 pocket of trypsin as usual, and (ii) upon complex formation, considerable conformation change occurs to the reactive site loop of the mutant SSI. Thus, in this case, flexibility of the reactive site loop seems important for successfully changing the proteinase specificity through mere replacement of the P1 residue.

Amino Acid Sequence↗
PubMed1992

Hematopoietic growth factors released by marrow stromal cells from patients with aplastic anemia.

We studied the production of granulocyte colony-stimulating factor (G-CSF), granulocyte-macrophage colony-stimulating factor (GM-CSF), and interleukin-6 (IL-6) by stromal cells from 33 patients with aplastic anemia (AA). Complete, confluent stromal layers were produced by 29 of the 33 samples using the long-term bone marrow culture (LTBMC) system. The concentration of G-CSF, GM-CSF, and IL-6 in culture media with or without interleukin-1 (IL-1) stimulation was determined by an enzyme-linked immunoadsorbent assay (ELISA). The spontaneous production of G-CSF, GM-CSF, and IL-6 did not differ significantly between normal controls and the patients with AA. The ability of stromal cells to release the three hematopoietic growth factors in response to IL-1 was either normal or elevated in all but one patient. We also studied the change in production of G-CSF, GM-CSF, and IL-6 by stromal cells before and after antilymphocyte globulin (ALG) therapy in 16 patients with AA. There was no correlation between the change in production of these cytokines and the response to ALG. In contrast to previous studies that showed a defect in the production of hematopoietic growth factors by stromal cells from patients with AA, the results indicated a normal or elevated production of G-CSF, GM-CSF, and IL-6 by marrow stromal cells in patients with AA.

Adolescent↗
PubMed1992

Aplastic anemia and viral hepatitis. Non-A, Non-B, Non-C?

OBJECTIVE: To test the hypothesis that the rare, often fatal, syndrome of hepatitis-associated aplasia is associated with hepatitis C virus infection. DESIGN: Case series. SETTING: Tertiary referral centers in the United States, Japan, Italy, and Germany. PATIENTS: Twenty-eight patients with onset of aplastic anemia within 90 days after seeking medical attention for jaundice, or having serum transaminase levels 150% or more of normal (hepatitis-associated aplasia patients) and three patients who developed aplastic anemia following liver transplantation for non-A, non-B hepatitis. OUTCOME MEASURES: Presence of hepatitis C in serum, bone marrow, and liver samples, detected by the polymerase chain reaction; antibody testing; and percentage of activated peripheral cytotoxic T lymphocytes determined by immunophenotyping. RESULTS: Hepatitis ribonucleic acid was present in the serum samples of 10 (36%) patients with hepatitis-associated aplasia. However, hepatitis C virus viremia was associated with transfusions received after the onset of aplasia: seven (58%) of 12 patients with hepatitis-associated aplasia who had received 21 or more units of blood products at the time of serum sampling were viremic, compared with only three (19%) of 16 patients with hepatitis-associated aplasia who had received 20 or less units of blood products (P less than .05). Hepatitis C virus was not found in blood and bone marrow samples of three National Institutes of Health case patients tested at the time of diagnosis. None of three livers from non-A, non-B hepatitis patients who developed aplastic anemia after liver transplantation contained hepatitis C virus ribonucleic acid. Activated CD8+ T lymphocytes were elevated three- to 20-fold early in the course of hepatitis-associated aplasia. CONCLUSIONS: Our results implicate a novel, non-A, non-B, and non-C agent in both hepatitis-associated aplasia and fulminant hepatitis.

Adolescent↗
PubMed1992

Detection of Philadelphia chromosome-positive acute lymphoblastic leukemia by polymerase chain reaction: possible eradication of minimal residual disease by marrow transplantation.

Minimal residual disease (MRD) in patients with Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph1 ALL) who received allogeneic (n = 9) or autologous (n = 6) bone marrow transplantation (BMT) was evaluated by the polymerase chain reaction (PCR) for the bcr-abl transcript. Twelve patients received BMT at the time of hematologic and cytogenetic remission. However, MRD was detected in 8 of 10 patients evaluated. Seven patients, including three who had MRD before BMT, continue to have a disease-free survival 5 to 64 months after BMT. Twenty-one specimens obtained from these patients at various times after BMT did not show MRD. In three patients, MRD detected just before BMT seems to be eradicated by BMT protocol. The other eight patients developed cytogenetic or hematologic relapses 2 to 8 months after BMT. Seven of 14 samples from these patients demonstrated MRD, which preceded clinical relapse by 3 to 9 weeks. Thus, this technique for the detection of MRD appears to be useful for the more precise assessment of various antileukemia therapies and for early detection of leukemia recurrence.

Adolescent↗
PubMed1992

Purification and structural analysis of hippocampal cholinergic neurostimulating peptide.

Hippocampal soluble fraction stimulates acetylcholine (AcCho) synthesis of medial septal nuclei in explant culture system. This stimulating activity was purified from 10-12-day-old rat hippocampus. During purification, the activity was separated into two fractions and a previously unreported peptide was purified from one fraction. The structure of this novel peptide is acetyl-Ala-Ala-Asp-Ile-Ser-Gln-Trp-Ala-Gly-Pro-Leu and we designated it as hippocampal cholinergic neurostimulating peptide (HCNP). Synthesized HCNP and de-acetylated HCNP (free-HCNP) stimulated AcCho synthesis of medial septal nuclei culture, in a dose-dependent manner, but not cultures of corpus striatum or anterior spinal cord. Mean half-maximal concentrations of HCNP and free-HCNP in AcCho synthesis of medial septal nuclei culture were 1.0 +/- 0.3 x 10(-10) M and 1.0 +/- 0.6 x 10(-11) M, respectively. Affinity purified polyclonal antibody to the free-HCNP neutralized the activity of crude hippocampal extract, as well as synthetic HCNP and free-HCNP. These observations suggested that HCNP was present in the hippocampal extract and was involved in development of specific cholinergic neuron in central nervous system.

Amino Acid Sequence↗
PubMed1992

Effect of continuous circular capsulorhexis and intraocular lens fixation on the blood-aqueous barrier.

Permeability across the blood-aqueous barrier to fluorescein was estimated fluorophotometrically in pseudophakic eyes for which a continuous circular capsulorhexis was performed. The permeability index was significantly higher in the in-the-bag fixations than in the out-of-the-bag fixations at 3 and 6 months after surgery, when only bilateral cases were enrolled. Damage to the barrier in eyes with the in-the-bag fixations was attributable to the broad attachment of optics to the anterior capsule, because a positive linear regression was obtained between the permeability index and the doughnut-shaped contact area in eyes with the in-the-bag fixations. The permeability index in eyes with the in-the-bag fixations was as low as that in eyes with the out-of-the-bag fixations when the contact area was small. These results indicate an unfavorable effect of the in-the-bag fixation with broad contact of the optics with the anterior capsule and, thus, suggest either an in-the-bag fixation with a large capsulorhexis or an out-of-the-bag fixation.

Adult↗
PubMed1992

cDNA sequence of three cysteine-rich clusters in the iron-sulfur subunit of complex II (succinate-ubiquinone oxidoreductase) from Caenorhabditis elegans determined by automated DNA sequencer.

Homology probing by using mixed primers for polymerase chain reaction (PCR) and a subsequent sequence analysis by automated DNA sequencer were applied to determine a partial cDNA sequence of the iron-sulfur subunit of complex II (succinate-ubiquinone oxidoreductase). Complex II is a membrane-bound flavoenzyme, which catalyzes the oxidation of succinate to fumarate in the tricarboxylic acid cycle, and it is a component of the mitochondrial and bacterial respiratory chains. In this study, the partial amino acid sequence of iron-sulfur subunits in Caenorhabditis elegans mitochondria was deduced from the DNA sequence obtained from cDNA-PCR. Mixed oligonucleotide primers corresponding to two conserved regions which appear to be the binding site for the prosthetic group were used. The product of PCR was cloned into plasmid vector pUC 119 and the sequence was determined from double strand plasmid DNA by the dideoxy method using of one-dye, four-lane type the automated DNA sequencer (DSQ-1, Shimadzu). The PCR product contained 483 nucleotides and its deduced amino acid sequence was highly homologous with that in human liver (68.9%) and that of Escherichia coli sdh B product (50.3%). As expected, striking sequence conservation was found around the three cysteine-rich clusters which have been thought to comprise the iron-sulfur centers of the enzyme.

Amino Acid Sequence↗
PubMed1992

Difference in tumor incidence and other tissue responses to polyetherurethanes and polydimethylsiloxane in long-term subcutaneous implantation into rats.

The long-term (1- and 2-year) adverse tissue responses including tumor formation by subcutaneous implantation of polyurethanes (PUs) and silicone (Sil) films into rats were compared. The weight-averaged molecular weights (Mw) of the PUs prepared from 4,4'-diphenylmethanediisocyanate, poly(tetramethyleneglycol) of Mn = 1000 and 1,4-butanediol are 220,000 (U-4), 124,000 (U-6), and 55,600 (U-8). The 50:50 mixed film of U-6 and silicone (U-6/sil) was prepared by roll-mixing of the noncured silicone and the U-6 solution followed by evaporation of the solvent and heat-curing at 70 degrees C. The tissue responses around implants were classified into four groups as follows: (A) tumor, (B) atypical cell proliferation accompanied by preneoplastic changes, (C) cell proliferation without preneoplastic changes, (D) no obvious responses. In both implantation periods, the PUs gave higher incidents of the adverse responses including tumor formation in comparison to Sil. No significant molecular weight-dependent trend was found in a 1-year study using U-4, 6, and 8. Significant PU-dose-dependent trends were found in a 2-year study: the total active incidence (A+B+C), U-6(22/29) greater than U-6/sil(11/29) greater than sil(7/28); tumor incidence (A), U-6(11/29) greater than U-6/sil(2/29) = sil(2/28). No detectable amounts of 4,4'-methylenedianiline (MDA) were found in the PUs. The methanol extracts from the PUs were negative in the mutagenicity tests. These indicate no relationship between the tumor formation by the PU films and the mutagenicities of the chemicals (mainly oligomers) leached from the PUs.

Aniline Compounds↗
PubMed1992

Endonuclease analyses of DNA of human herpesvirus-6 isolated from blood before and after bone marrow transplantation.

Three strains of human herpesvirus-6 (HHV-6) were isolated from peripheral blood mononuclear cells of a leukemic child with the antibody of HHV-6 before and after bone marrow transplantation (BMT); two strains were obtained before BMT and one after BMT. The DNA extracted from the three isolates was analyzed by six different restriction endonucleases. The cleavage profiles of two strains obtained before BMT were different, but the third strain isolated after BMT was identical with one of the two, which suggest reactivation of HHV-6 from the recipient's own body after BMT and possible mutation or super-infection of the virus in an immunocompromised patient.

Bone Marrow Transplantation↗
PubMed1992

Existence of lipid vesicles containing platelet-activating factor in endothelial cell lysate.

Platelet aggregation activity due to platelet-activating factor (PAF) was detected at high molecular weight (HMW) and low molecular weight fractions after gel-filtration chromatography of cell lysate of endothelial cells. [3H]PAF added to the cell lysate was similarly distributed after chromatography. The radioactivity associated with HMW fraction was not reduced by digesting the lysate with trypsin, suggesting that PAF was not making complexes with proteins but was included in lipid vesicles in cell lysate. Further evidence showed that an unknown specific factor(s) was needed to form these PAF-containing lipid vesicles. Radioactivity was not found in HMW fraction when [3H]PAF was mixed with cell lysate of vascular smooth muscle cells. When monomeric PAF was added to endothelial cell lysate, the specific activity of aggregation decreased to the level exerted by endogenous PAF-containing lipid vesicles due to incorporation into lipid vesicles. PAF in the form of lipid vesicles was more stable in plasma than monomeric form.

Animals↗
PubMed1992

Cerebral blood flow and cerebral oxygen consumption in patients with COPD on mechanical ventilation.

OBJECTIVE: To investigate the effect of PaCO2 on cerebral blood flow (CBF) in chronic obstructive pulmonary disease (COPD). DESIGN: Before-after trial. SETTING: General ICU in a regional hospital. PATIENTS: 7 patients undergoing mechanical ventilation because of an exacerbation of COPD. INTERVENTION: CBF and cerebral metabolic rate of oxygen (CMRO2) of COPD were measured before and after hyperventilation and were compared by those of normal patients. CBF was measured by the Kety-Schmidt technique using 15% N2O. MEASUREMENTS/RESULTS: Hyperventilation produced a significant reduction in CBF in COPD with no concomitant change in CMRO2. CMRO2 in COPD was significantly lower than those in normal patients. The regression equation was shifted significantly more to the right in COPD. CONCLUSION: The sensitivity of CBF in CO2 remained but CMRO2 was reduced markedly in COPD patients.

Adult↗