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Biomedical subjects

S Yoshida

Publications and source records attributed to S Yoshida.

At least 577 records · Page 32Linked to original sources
PubMed1998

Effect of yeast extract supplementation in leach solution on bioleaching rate of pyrite by acidophilic thermophile acidianus brierleyi

The bioleaching rate of pyrite (FeS2) by the acidophilic thermophile Acidianus brierleyi was studied at 65 degrees C and pH 1.5 with leach solutions supplemented with yeast extract. In the absence of yeast extract supplementation, A. brierleyi could grow autotrophically on pyrite, and the leaching percentage of pyrite particles (25-44 μm) reached 25% for 7 d. The bacterial growth and consequent pyrite oxidation were enhanced by the addition of yeast extract between 0.005 and 0.25% w/v: the pyrite particles were completely solubilized within 6 d. The bioleaching rate was enhanced by a factor of 1.5 when the yeast extract concentration was changed from 0.005 to 0.05% w/v. However, there was only a slight effect on the leaching rate at the yeast extract concentrations of 0.05 to 0. 25% w/v, suggesting that the organic supplement level was in large excess in the pyrite bioleaching. Copyright 1998 John Wiley & Sons, Inc.

Journal Article↗
PubMed1998

Changes in intracellular Ca2+ concentrations related to PDT-induced apoptosis in photosensitized human cancer cells.

For photodynamic therapy (PDT), human squamous cell carcinoma cells (HSC-2) were treated with 3 microg/ml of photofrin 24 h prior to irradiating the cultures with the excimer dye laser at a dose of 2 J/cm2. Extensive DNA fragmentation was recognized within 2 h of PDT. The proportion of cells with DNA fragmentation on flow cytometric analysis was significantly increased to 44 and 78% at 1 and 2 h after PDT, respectively, compared to control groups. Confocal laser scanning microscopy revealed a slight change in the intracellular Ca2+ concentration occurring at 30 min after PDT and a subsequent marked increase in the Ca2+ concentration 1-2 h after PDT, but no change was observed in the cells exposed to laser irradiation alone and to photofrin alone and in the cells immediately after PDT. These findings suggest that an increase in the intracellular Ca2+ concentration may play an important role in the induction of PDT-induced apoptosis.

Antineoplastic Agents↗
PubMed1998

Sequence analysis and expression of human neuropsin cDNA and gene.

Neuropsin is a serine protease which is thought to function in a variety of tissues including the brain and skin. This protease has been shown to have important roles in neural plasticity in mice. Here we have cloned a cDNA and analyzed the gene for human neuropsin by polymerase chain reaction-based strategies. The cDNA had 72% identity to mouse neuropsin. The deduced amino acid sequence showed 72% identity to mouse neuropsin. Key amino acid residues for the enzyme activity and all cysteine residues were conserved between human and mouse neuropsin. The gene for human neuropsin had six exons and five introns, and the gene organization is similar to trypsin-type serine proteases. The mRNA was expressed in primary cultures of keratinocytes.

Amino Acid Sequence↗
PubMed1998

Sulfated glycoglycerolipid from archaebacterium inhibits eukaryotic DNA polymerase alpha, beta and retroviral reverse transcriptase and affects methyl methanesulfonate cytotoxicity.

A sulfated glycoglycerolipid, 1-O-(6'-sulfo-alpha-D-glucopyranosyl)-2,3-di-O-phytanyl- sn-glycerol (KN-208), a derivative of the polar lipid isolated from an archaebacterium, strongly inhibited DNA polymerase (pol) alpha and pol beta in vitro among 5 eukaryotic DNA polymerases (alpha, beta, gamma, delta, and epsilon). It also inhibited Escherichia coli DNA polymerase I Klenow fragment (E. coli pol I) and human immunodeficiency virus reverse transcriptase (HIV RT). The mode of inhibition of these polymerases was competitive with the DNA template primer and was non-competitive with the substrate dTTP. KN-208 inhibited pol beta most strongly, with a Ki value of 0.05 microM, 10-fold lower than that for pol alpha (0.5 microM) and 60- or 140-fold lower than that for HIV RT (3 microM) or for E. coli pol I (7 microM), respectively. The loss of sulfate on the 6'-position of glucopyranoside of this compound completely abrogated inhibition. However, the hydrophilic part of KN-208, glucose 6-sulfate alone, showed no inhibition. Other sulfated compounds containing different hydrophobic structures, such as dodecyl sulfate and cholesterol sulfate, exhibited a much weaker inhibition. Our results suggest that the whole molecular structure of KN-208 is required for inhibition. KN-208 was shown to be modestly cytotoxic for the human leukemic cell line K562. Interestingly, a subcytotoxic dose of KN-208 increased the sensitivity of the human leukemic cells to an alkylating agent, methyl methanesulfonate, while it did not potentiate the effects of ultraviolet light or of cisplatin.

Archaea↗
PubMed1998

Premorbid personality traits of patients with organic (ICD-10 F0), schizophrenic (F2), mood (F3), and neurotic (F4) disorders according to the five-factor model of personality.

The present article aims to examine premorbid personality traits of psychiatric patients with various diagnoses by asking their close relatives to retrospectively rate the patients' usual self with a questionnaire designed for the five-factor model of personality, a rapidly emerging comprehensive theory of personality structure. Data for 140 patients and 84 controls were analyzed. Although psychiatric patients as a group were characterized by high neuroticism and low conscientiousness when compared with the healthy controls, there were only a few traits that distinguished a particular diagnostic group from either the normal control or from the rest of the patients: neurotic disorder patients had higher neuroticism scores than the normal controls; unipolar depressives had a higher conscientiousness score than the rest of the patient group. No salient premorbid trait was noted for patients with organic mental disorders, schizophrenic disorders or bipolar disorders.

Adult↗
PubMed1998

Serum DNA polymerase beta as an indicator for fatal liver injury of rat induced by D-galactosamine hydrochloride and lipopolysaccharide.

DNA polymerase beta (pol beta) is a nuclear enzyme that is tightly bound to chromatin. Release of the pol beta activity into serum, therefore, may indicate the occurrence of massive destruction of cell nuclei in organs or tissues. In the present study, we made a liver injury model rat by the intraperitoneal injection of D-galactosamine hydrochloride (GalN, 500 mg/kg) and lipopolysaccharide (LPS, 100 microg/kg). Serum from the GalN/LPS-treated rats showed a high level of pol beta activity up to 118 pmol/0.5 microl serum (4700 cpm) at 12 h after the treatment, while the control rat serum showed the back ground level (3.8 pmol/0. 5 microl, 150+/-70 cpm). The serum pol beta activity was sensitive to inhibition by 2',3'-dideoxyTTP and by an anti-rat pol beta antibody. Among 30 rats treated with GalN/LPS, 10 rats died within 120 h (dead group). Serum pol beta activity in the dead group was as high as 23.0+/-19.5 pmol/0.5 microl (925+/-778 cpm) at 10 h after the treatment, while in alive group (n=20), it was 3.7+/-3.2 pmol. Levels of the serum pol beta activity correlated well with the prognosis of GalN/LPS-treated rats based on an analysis of the receiver-operator characteristic curves.

Alanine Transaminase↗
PubMed1998

Characterization of recombinant and brain neuropsin, a plasticity-related serine protease.

Activity-dependent changes in neuropsin gene expression in the hippocampus implies an involvement of neuropsin in neural plasticity. Since the deduced amino acid sequence of the gene contained the complete triplet (His-Asp-Ser) of the serine protease domain, the protein was postulated to have proteolytic activity. Recombinant full-length neuropsin produced in the baculovirus/insect cell system was enzymatically inactive but was readily converted to active enzyme by endoprotease processing. The activational processing of prototype neuropsin involved the specific cleavage of the Lys32-Ile33 bond near its N terminus. Native neuropsin that was purified with a purity of 1,100-fold from mouse brain had enzymatic characteristics identical to those of active-type recombinant neuropsin. Both brain and recombinant neuropsin had amidolytic activities cleaving Arg-X and Lys-X bonds in the synthetic chromogenic substrates, and the highest specific activity was found against Boc-Val-Pro-Arg-4-methylcoumaryl-7-amide. The active-type recombinant neuropsin effectively cleaved fibronectin, an extracellular matrix protein. Taken together, these results indicate that this protease, which is enzymatically novel, has significant limbic effects by changing the extracellular matrix environment.

Amino Acid Sequence↗
PubMed1998

Mismatched nucleotides may facilitate expansion of trinucleotide repeats in genetic diseases.

We have studied the contribution of mismatch sequences to the trinucleotide repeat expansion that causes hereditary diseases. Using an oligonucleotide duplex, (CAG)5/(CTG)5, as a template-primer, DNA synthesis was carried out using either Escherichia coli DNA polymerase I (Klenow fragment) or human immunodeficiency virus type I reverse transcriptase (HIV-RT). Both enzymes expanded the repeat sequence longer than 27 nucleotides (nt), beyond the maximum length expected from the template size. The expansion was observed under conditions in which extension occurs either in both strands or in one strand. In contrast, with another template-primer that contains a non-repetitive flanking sequence 5'-upstream of the repetitive sequence, the reaction products were not extended beyond the template size (45 nt) by these DNA polymerases. We then used mismatched template-primers, in which either 1, 2 or 6 non-complementary nucleotides were introduced to the repeat sequence that is flanked by a non-repetitive sequence. In this case, primers were efficiently expanded over the expected length of 45 nt, in a mismatch-dependent manner. One of the primers with six mismatches extended as long as 72 nt. These results imply that the misincorporation of non-complementary deoxyribonucleoside monophosphates (dNMPs) into the repeat sequence makes double-stranded DNA unstable and triggers the slippage and expansion of trinucleotide repeats by forming loops or hairpin structures during DNA synthesis.

Base Sequence↗
PubMed1998

Reversed-phase ion-pair chromatographic analysis of tetracycline antibiotics. Application to discolored teeth.

A high-performance liquid chromatographic method with diode array detection was developed to simultaneously separate tetracycline antibiotics and applied to the analysis of discolored teeth. By a reversed-phase ion-pair chromatographic system using pentanesulfonate as a counter ion, minocycline, oxytetracycline, tetracycline and demeclocycline were eluted in this order, and they showed base-line separation within 9 min. When using oxytetracycline as an internal standard, the quantitative ranges were between 2.5 ng/ml and 7.5 microg/ml. Powdered dentine (10 mg) and enamel (40 mg) prepared from discolored primary teeth were sonicated in 0.25 ml of 10 mM HCl containing oxytetracycline (0.75 microg/ml) and 50 mM EDTA-2Na, thereafter the supernatants were chromatographed. Eluates from both discolored tooth samples were identified as minocycline based on diode array spectra of their peaks, while minocycline was not detected in any samples from nondiscolored normal teeth, indicating that discoloration of the tested teeth was due to minocycline incorporated into dentine and enamel. Replicate quantitative analyses of the identical tooth substances showed that intra- and inter-assay C.V.s were 2.63 and 4.95% for dentine, and 5.42 and 10.88% for enamel. Application of the developed method to nine discolored teeth revealed that the incorporated minocycline ranged from 20.13 to 84.62 ng/mg of dentine and 0.89 to 7.87 ng/mg of enamel.

Anti-Bacterial Agents↗
PubMed1998

The inhibitory effect of novel triterpenoid compounds, fomitellic acids, on DNA polymerase beta.

We previously found new triterpenoid compounds, designated fomitellic acid A and B, which selectively inhibit the activities of mammalian DNA polymerase alpha and beta in vitro. On DNA polymerase beta, the fomitellic acids acted by competing with both the substrate and the template primer, but on DNA polymerase alpha, they acted non-competitively. At least on DNA polymerase beta, the evidence suggests that each of the fomitellic acids bind to the active region competing with the substrate and/or template primer, and subsequently inhibits the catalytic activity. We therefore further investigated the enzyme-binding properties by using DNA polymerase beta and its proteolytic fragments. The 39 kDa enzyme was proteolytically separated into two fragments of the template-primer-binding domain (8 kDa) and the catalytic domain (31 kDa). The fomitellic acids bound tightly to the 8 kDa fragment, but not to the 31 kDa fragment. The immuno-precipitation by antibodies against the enzyme or each of the fragments also proved the binding. These results suggest that the fomitellic acid molecule competes with the template-primer molecule on its 8 kDa binding site, binds to the site, and the fomitellic acid molecule simultaneously disturbs the substrate incorporation into the template primer.

Animals↗
PubMed1998

Quantification of concanavalin A binding to rat brain microsomal membranes detected by fluorescence polarization technique.

A high sensitive method for detecting the change of microsomal membrane surface oligosaccharides was developed to study the regulatory role of lipid- or peptide-linked mannoside of endoplasmic reticulum in synaptic functions. The binding of concanavalin A to the microsomal membrane surface was measured quantitatively using a microgram-order of rat brain microsomal proteins. The fluorescence polarization of concanavalin A (Con A)-fluorescein isothiocyanate (FITC) conjugate bound to the membrane was analyzed to quantitate the change of binding constant and the number of binding sites. As a control, the non-specific binding of bovine serum albumin-FITC conjugate was measured by the same technique. We measured the change of fluorescence intensity of membrane-bound FITC conjugates by the flow cytometry and found that the intensity of FITC conjugate bound to the membrane increased more than that of free form of the probe. We observed that the alpha-mannosidase-treatment of rat brain microsomes resulted in the increase of binding constant of Con A to the microsomal surface without significant loss of binding sites.

Animals↗
PubMed1998

Epidemiology of motor neuron disease in the Kii Peninsula of Japan, 1989-1993: active or disappearing focus?

During the period 1989-1993, the incidence and migration patterns of patients with motor neuron diseases (MND) in Wakayama Prefecture, including one of the high-incidence Kii Peninsula foci ('Kozagawa focus'), were surveyed to determine whether the focus had truly disappeared or not. Overall, the crude average annual incidence was 1.43 per 100000 population; when age-adjusted to the 1990 Japanese population, it was 1.25 (1.85 for males and 0.61 for females). The average annual age- and sex-specific incidence steadily increased to a peak between 60 and 69 years and dropped after 70. Geographically, the rates varied in the five regions of Wakayama Prefecture from 0.38 to 2.48. The areas with high incidence were distributed in the central and southernmost regions; the highest was in the Kozagawa focus with 9.54 (two ALS cases within five years; 4193 base population, 1990). During the study period, four emigrants from Kozagawa had developed MND one to four decades after leaving the focus. Although the remarkable clustering of MND was thought to have disappeared, the southern Kii Peninsula remains a high-risk area for MND, especially if one interprets the data so as to include the emigrants. In general, the age at onset has increased in the past 20 years from 56.5 to 61.7; male predominance is observed.

Adult↗
PubMed1998

Identification of a sex steroid-inducible gene in the neonatal rat hypothalamus.

By the cDNA subtraction between cDNA preparations from androgenized and intact neonate rats hypothalami, granulin/ epithelin (grn) gene was identified as a gene enriched by androgenization. Strong grn mRNA signals were detected by in situ hybridization in the ventromedial nucleus (VMH) and the arcuate nucleus (ARC) of the hypothalamus of a 5-day-old male. The grn gene expression level in the hypothalamus was similar between males and females at birth. At 10 days of age, this level was maintained in males, but decreased to 1/4 in females. Thus, grn can be the gene of which expression in the VMH and ARC is sustained by endogenous androgen in male neonates.

Animals↗
PubMed1998

Studies on inhibitors of mammalian DNA polymerase alpha and beta: sulfolipids from a pteridophyte, Athyrium niponicum.

Three sulfolipid compounds, 1, 2, and 3, have been isolated from a higher plant, a pteridophyte, Athyrium niponicum, as potent inhibitors of the activities of calf DNA polymerase alpha and rat DNA polymerase beta. The inhibition by the sulfolipids was concentration dependent, and almost complete inhibition of DNA polymerase alpha and DNA polymerase beta was achieved at 6 and 8 microg/mL, respectively. The compounds did not influence the activities of calf thymus terminal deoxynucleotidyl transferase, prokaryotic DNA polymerases such as the Klenow fragment of DNA polymerase I, T4 DNA polymerase and Taq polymerase, the DNA metabolic enzyme DNase I, and even a DNA polymerase from a higher plant, cauliflower. Similarly, the compounds did not inhibit the activity of the human immunodeficiency virus type 1 reverse transcriptase. The kinetic studies of the compounds showed that DNA polymerase alpha was inhibited non-competitively with respect to the DNA template and substrate, whereas DNA polymerase beta was inhibited competitively with both the DNA template and substrate. The binding to DNA polymerase beta could be stopped with non-ionic detergent, but the binding to DNA polymerase alpha could not.

Animals↗
PubMed1998

Radiotherapy for Kimura's disease: the optimum dosage.

PURPOSE: To evaluate retrospectively the optimum dosage of irradiation for Kimura's disease. METHODS AND MATERIALS: Twenty patients with Kimura's disease were treated with radiotherapy. The sex ratio was 19 males to 1 female. The mean ages at onset, initial treatment, and radiotherapy were 26.2, 29.5, and 32.2 years, respectively. Radiotherapy was mainly applied for residual or recurrent tumors. The eosinophil count increased by more than 10% in 18 of the 20 patients. In most instances, irradiation was given through a single field with dosages ranging from 20 to 44 Gy. RESULTS: At the completion of radiotherapy, a marked response in tumor size was noted in all cases. The minimum follow-up was 48 months. Local control was obtained in 23 of 31 lesions (74.1%). At dosages of < or =25 Gy, 26-30 Gy, and > 30 Gy, local control was obtained in 2 of 8 (25.0%), 9 of 10 (90.0%), and 12 of 13 sites (92.3%), respectively. CONCLUSIONS: Radiotherapy is an effective treatment for Kimura's disease. This strongly suggests that no surgical procedure other than a biopsy should be carried out. The radiation field should be limited to the lesion and swelling of the adjacent lymph nodes as much as possible, with a optimum dosage of 26-30 Gy regardless of tumor size.

Adolescent↗
PubMed1998

Paracrine effects of bFGF and KGF on the process of mouse blastocyst implantation.

Implantation is a complex process that requires the interaction of the blastocyst, and subsequently, that of the developing embryos with the endometrium. Several growth factors and cytokines are involved in implantation, but the details of their actions as related to the regulation of blastocyst implantation remain unclear. In the present study, the RT-PCR method was used to determine the gene expression of basic fibroblast growth factor (bFGF), keratinocyte growth factor (KGF), FGF receptor 1 (FGFR1), FGF receptor 2 (FGFR2), and KGF receptor (KGFR) in mouse embryos and in the stromal and epithelial cells of the uterine endometrium. Basic FGF and KGF mRNA were expressed in the endometrial cells, but were not expressed in the embryos. The mRNAs of receptors for bFGF and KGF were expressed in the blastocysts and in the in vitro implanting embryos, suggesting that bFGF and KGF may exert paracrine effects on blastocyst implantation. In this mouse model of blastocyst implantation, it was found that transforming growth factor alpha (TGF-alpha) at the concentrations of 1 ng/ml and 10 ng/ml significantly enhanced the blastocyst attachment and trophoblast spreading and increased trophoblast surface area. Relatively high concentrations of bFGF (100-500 ng/ml) significantly enhanced the rates of blastocyst attachment and of trophoblast spreading and promoted the expansion of the surface area of the implanting embryos. Unlike the rates of blastocyst attachment and trophoblast spreading, the surface area of the spreading embryos was significantly increased by addition of KGF (1-100 ng/ml). These results suggest that the bFGF and KGF derived from the endometrial cells exert paracrine effects on the process of implantation by stimulating trophoblast outgrowth through their cognate receptors.

Animals↗
PubMed1998

Neurotoxicity of intrathecal Shiga toxin 2 and protection by intrathecal injection of anti-Shiga toxin 2 antiserum in rabbits.

The initial brain lesions in rabbits given intravenous Shiga toxin 2 (Stx2) were noted at 24 h in an area around the third ventricle (Fujii et al., Infect Immun 1996, 64: 5053-60). This result implied that Stx2 is present in the cerebrospinal fluid (CSF) despite the fact that the toxin was administered intravenously. We measured Stx2 activity in CSF by using a Vero cell cytotoxicity assay at various times after an intravenous injection of Stx2. Stx2 was detected from 2 h after the injection, and its concentration in CSF remained at a high level for a further 6 h. Fifty percent lethal doses (LD 50) of Stx2 were measured in rabbits after intravenous and intrathecal Stx2 injections; The LD 50 after an intrathecal injection of Stx2 was 0. 36 microg/kg, which was 9.2-fold lower than that of an intravenous injection of Stx2 (3.4 microg/kg). Magnetic resonance images obtained after an intrathecal Stx2 injection (5 microg/kg) were compared with those obtained after an intravenous Stx2 injection (5 microg/kg). At 48 h, the cerebellar lesions had spread from the area in contact with the CSF on a T2-weighted image, which suggests that the intrathecal Stx2 may invade the cerebellum directly. We then examined whether anti-Stx2 antiserum injected intrathecally protects rabbits against brain damage. Eighty percent of the rabbits infected with Stx2 at 5 microg/kg died within 8 days from brain damage. Rabbit anti-Stx2 sera (with titres of x16 and x64 by the Ouchterlony precipitation method) were administered into the CSF space through the cisterna magna. All the rabbits ( n=10) survived when they were given an intrathecal injection of rabbit anti-Stx2 antiserum 2 h before the intravenous injection of Stx2. Our results suggest that a leakage of Stx2 into the CSF from the choroid plexus causes brain damage, and that an intrathecal injection of anti-Stx2 antiserum could be a therapy for acute encephalopathy caused by Stx2-producing Escherichia coli.

Animals↗