Biomedical subjects

N Miyata

Publications and source records attributed to N Miyata.

At least 37 records · Page 2Linked to original sources

PubMed2001

Production of anti-Gordonia amarae mycolic acid polyclonal antibody for detection of mycolic acid-containing bacteria in activated sludge foam.

Mycolic acid-containing actinomycetes (mycolata) are considered the causative agents of foaming of activated sludge and scum formation in activated sludge treatment plants. In this study, the production of anti-Gordonia amarae mycolic acid polyclonal antibodies was investigated. Rabbits were immunized with a conjugate of keyhole limpet hemocyanin and mycolic acids of G. amarae, which contained 48 to 56 carbon atoms (average, 52.0). Enzyme-linked immunosorbent assay (ELISA) demonstrated that the polyclonal antibodies could recognize cells of G. amarae ranging from 0.1 to 10 microg. The antibodies also reacted with other tested mycolata strains belonging to the genera Nocardia, Rhodococcus, Dietzia, Mycobacterium and Tsukamurella. However, reactivities against other gram-positive and gram-negative bacteria not containing mycolic acid were negligible or much lower. The results indicate that the anti-G. amarae mycolic acid antibodies show a reactivity selective for a group of mycolata involved in the foaming of activated sludge.

Journal Article↗

PubMed2001

Formation of stable foam by the cells and culture supernatant of Gordonia (Nocardia) amarae.

Gordonia amarae is the cause of foaming activated sludge. In this study, the mechanism of foam formation by G. amarae SC1 was investigated. A liquid culture of SC1 cells generated a stable foam when shaken reciprocally. This foam formation was dependent on the presence of both bacterial cells and culture supernatant. A high-molecular-weight fraction (Mw>10000) of the supernatant was capable of emulsifying n-hexadecane in addition to exhibiting foaming activity, indicating that it contains a surface-active substance(s). The bacterial cells showed a high affinity to hexadecane. This hydrophobic cell surface property might be involved in the attachment of cells to air bubbles to generate a stable foam. The results demonstrated the participation of cells and the extracellular biosurfactant in the formation and stabilization of foam in G. amarae SC1 culture.

Journal Article↗

PubMed2000

Synthesis, biological evaluation, and conformational analysis of A-ring diastereomers of 2-methyl-1,25-dihydroxyvitamin D(3) and their 20-epimers: unique activity profiles depending on the stereochemistry of the A-ring and at C-20.

All eight possible A-ring diastereomers of 2-methyl-1, 25-dihydroxyvitamin D(3) (2) and 2-methyl-20-epi-1, 25-dihydroxyvitamin D(3) (3) were convergently synthesized. The A-ring enyne synthons 19 were synthesized starting with methyl (S)-(+)- or (R)-(-)-3-hydroxy-2-methylpropionate (8). This was converted to the alcohol 14 as a 1:1 epimeric mixture in several steps. After having been separated by column chromatography, each isomer led to the requisite A-ring enyne synthons 19 again as 1:1 mixtures at C-1. Coupling of the resulting A-ring enynes 20a-h with the CD-ring portions 5a,b in the presence of a Pd catalyst afforded the 2-methyl analogues 2a-h and 3a-h in good yield. In this way, all possible A-ring diastereomers were synthesized. The synthesized analogues were biologically evaluated both in vitro and in vivo. The potency was highly dependent on the stereochemistry of each isomer. In particular, the alpha alpha beta-isomer 2g exhibited 4-fold higher potency than 1 alpha,25-dihydroxyvitamin D(3) (1) both in bovine thymus VDR binding and in elevation of rat serum calcium concentration and was twice as potent as the parent compound in HL-60 cell differentiation. Furthermore, its 20-epimer, that is, 20-epi-alpha alpha beta 3g, exhibited exceptionally high activities: 12-fold higher in VDR binding affinity, 7-fold higher in calcium mobilization, and 590-fold higher in HL-60 cell differentiation, as compared to 1 alpha,25-dihydroxyvitamin D(3) (1). Accordingly, the double modification of 2-methyl substitution and 20-epimerization resulted in unique activity profiles. Conformational analysis of the A-ring by (1)H NMR and an X-ray crystallographic analysis of the alpha alpha beta-isomer 2g are also described.

Animals↗

PubMed2000

Bioactivity and mechanical properties of PDMS-modified CaO-SiO(2)-TiO(2) hybrids prepared by sol-gel process.

Hydrolysis and polycondensation of poly(dimethylsiloxane) (PDMS), tetraethoxysilane (TEOS), tetraisopropyltitanate (TiPT), and calcium nitrate gave essentially pore- and crack-free transparent monolithics of PDMS-modified CaO-SiO(2)-TiO(2) hybrids, when PDMS/(TEOS + TiPT) was larger than 26:74 in weight, under constant ratios of TEOS/TiPT of 9:1 in mol and Ca/(TEOS + TiPT) of 0.15 in mol. Their apatite-forming abilities in a simulated body fluid, which is indicative of bioactivity, increased with decreasing PDMS/(TEOS + TiPT). Their extensibility and Young's modulus decreased and increased, respectively, with decreasing PDMS/(TEOS + TiPT). The hybrids with PDMS/(TEOS + TiPT) of about 30:70 in weight showed fairly high apatite-forming ability, high extensibilities, and Young's moduli almost equal to those of the human cancellous bones. These new kind of bioactive materials with unique mechanical properties may be useful as bone-repairing materials.

Apatites↗

PubMed2000

Thermal decomposition of an ultrathin Si oxide layer around a Si(001)-(2 x 1) window.

We examine the thermal decomposition of an ultrathin Si oxide layer around a Si(001)-(2 x 1) window opened by electron-beam-induced selective thermal decomposition. The decomposition progresses at the oxide/Si(001)-(2 x 1) boundary and follows two rate-limiting steps with activation energies of 4.0 and 1.7 eV. We propose that the former and latter energies correspond to the reaction of Si monomer with the oxide and the desorption of the SiO into the vacuum, respectively.

Journal Article↗

PubMed2000

Trans-4-hydroxy-2-nonenal, an aldehydic lipid peroxidation product, lacks genotoxicity in lacI transgenic mice.

In order to cast light on the significance of lipid peroxidation products for carcinogenesis, the lacI mutant frequency (MF), micronucleus induction and cell proliferation were analyzed in lacI transgenic mice treated with trans-4-hydroxy-2-nonenal (HNE), a typical example. Male mice were ip injected with HNE at doses of 0, 5 or 50 mg/kg bw and 48 h thereafter, peripheral blood was collected for analyzing micronucleus induction. After 14 days, the mice were sacrificed to allow tissue sampling for examination of lacI MF and cell proliferative activity. Sixty percent of the mice given 50 mg/kg HNE died within 5 days after the treatment, but no other mortalities were observed. Histopathologically, marked pulmonary hemorrhage was found in the 50 mg/kg HNE group mice that survived until day 14. Immunohistochemically, HNE-modified proteins were detected in their alveolar macrophages. The HNE treatment did not increase lacI MF in the liver, kidney and lung and no significant increase in micronucleus induction or cell proliferation in major organs was found in either treatment. Moreover, no tumors developed in the 5 mg/kg HNE-treated mice which survived until week 78. Our results thus indicate that HNE lacks in vivo genotoxicity in lacI transgenic mice even when lethal doses are applied.

Aldehydes↗

PubMed2000

Microbial decolorization of melanoidin-containing wastewaters: combined use of activated sludge and the fungus Coriolus hirsutus.

A white rot fungus, Coriolus hirsutus, exhibited a strong ability to decolorize melanoidin in cultures not supplemented with nitrogenous nutrients. Addition of peptone to the cultures lowered the ability of the fungus to decolorize melanoidin, but that of inorganic nitrogens (Ns), ammonium and nitrate did not bring about any marked reduction in the ability. These results suggest an inhibitory effect of organic N on melanoidin decolorization. Therefore, for enhancing the decolorization of melanoidin in wastewaters by the fungus, activated sludge pretreatment of the wastewaters was expected to be effective, i.e., activated sludge is capable of converting available organic N into inorganic N. To confirm this, waste sludge heat treatment liquor (HTL), wastewater from a sewage treatment plant, was pretreated with activated sludge. In practice, pretreatment of HTL under appropriate conditions accelerated the fungal decolorization of HTL. In the pretreated HTL, the fungus was shown to produce a high level of manganese-independent peroxidase (MIP). Addition of Mn(II) to the pretreated HTL caused a further increase in the decolorization efficiency of the fungus and a marked increase in the manganese peroxidase (MnP) activity. Consequently, the increases in MIP and MnP activities were considered to play an important role in the enhanced ability of C. hirsutus to decolorize HTL.

Journal Article↗

PubMed2000

Rapid detection of Nocardia amarae in the activated sludge process using enzyme-linked immunosorbent assay (ELISA).

Nocardia amarae, a mycolic acid-containing bacterium, has often been reported to cause foaming of activated sludge in wastewater treatment plants. In this study, the number of N. amarae cells in the activated sludge process was estimated by enzyme-linked immunosorbent assay (ELISA) with anti-N. amarae polyclonal antibody. Use of the antibody enabled N. amarae to be detected at levels of 10(4) to 10(7) colony forming units. On the other hand, the antibody reacted with only a small portion of activated sludge, in which no N. amarae cells were detected by the plate count method. Competitive ELISA was employed to estimate the N. amarae cells in samples taken from a municipal wastewater treatment plant, including raw wastewater and activated sludge foam. The cell numbers estimated by competitive ELISA corresponded well with those obtained by plate counts. Hence, the antibody produced in this study was shown to be effective for the rapid monitoring of N. amarae in the activated sludge process.

Journal Article↗

PubMed2000

Clinical features of human T-lymphotropic virus type 1 uveitis: a long-term follow-up.

To investigate the clinical manifestations of human T-lymphotropic virus type-1 uveitis (HU), 112 HU patients who were followed up periodically for more than one year were retrospectively analyzed with respect to their ophthalmological and systemic complications. The gender ratio (female/male ratio) of the HU patients was 2.0 and the initial complications were foggy vision in 34.5%, ocular floaters in 33.3%, and blurred vision in 15.5%. As for the ocular symptoms, the majority (78.6%) of patients were classified as intermediate uveitis with vitreous inflammation. Recurrence of uveitis episodes was seen in one half of the patients (51.8%); 12 patients had more than six uveitis episodes. The interval of uveitis episodes varied from two weeks to 10 years. Nearly one half of the patients (43.8%) had ocular complications: e.g., cataract in 22 patients, persistent vitreous opacities in 17 patients, and glaucoma in 16 patients. Although the visual prognosis was essentially good, 11 patients had poor visual prognosis (<0.1). The causes of poor vision in these patients were cataract, cystoid macular edema, epiretinal membrane, and optic nerve atrophy. Of the 112 HU patients, two developed HTLV-I-associated myelopathy (TSP/HAM) after the onset of HU, while none developed adult T-cell leukemia. Sixteen HU patients had a previous history of Graves' disease and a past history of methimazole therapy, while Graves' disease was found in another HU patient only after HU onset and methimazole was not administered before the onset of HU. The present data of long-term follow-up indicate that (1) HU causes various ocular complications and its visual prognosis can be poor, (2) TSP/HAM can be induced even after the onset of HU, and (3) methimazole is not a risk factor of HU after Graves' disease.

Adult↗

PubMed2000

Hydroxylation of nitrated naphthalenes with KO2/crown ether.

Superoxide radical anion (O2*-), generated by KO2/crown ether, is effective for hydroxylation of nitronaphthalenes. When mono- and di-nitronaphthalenes are treated with KO2/crown ehter, hydroxylation results at the electron-deficient site caused by the electron withdrawing effect of the substituted nitro group. Kinetic experiments suggest that the hydroxylation proceeds by two different mechanisms dependent on the first one-electron reduction potential of nitronaphthalenes.

Ethers, Cyclic↗

PubMed2000

Synthesis, conformation, and chemical properties of new mini parallel double-stranded peptides conjugated with -Phe-Phe- and -Phe-Phe-X-sequences.

To investigate the chemical conformations and functions of the -Phe-Phe-Val- or -Phe-Phe- sequences contained in the Alzheimer's disease related beta-amyloid peptide, a series of mini parallel double-stranded peptides conjugated with two peptide residues to one spacer were designed and prepared. The structure of the compounds was elucidated by circular dichroism (CD) spectrum and NMR two dimensional (2D) nuclear Overhauser enhancement and exchange spectroscopy (NOESY) measurments. The structure of 1,2-ethano-bis(L-Phe-L-Phe-L-Leu), 1,12-dodecano-bis(L-Phe-L-Phe-L-Leu), 1,12-dodecano-bis(L-Phe-L-Phe-L-Val), and 1,12-dodecano (D-Phe-D-Phe-D-Leu) conjugated with L-Leu and L-Val residues show a beta-turn-like nucleation. The dihedral angles (theta = +75 degrees, omega = +180 degrees, phi = +90 degrees, phi = -87 degrees, psi = +180 degrees) obtained from experimental coupling constant (J) data, etc. support that 1,12-dodecano-bis(L-Phe-L-Phe) adopts beta-turn mimic nucleation. The 1,12-dodecano- bis(L-Leu-L-Leu-L-Phe), 1,12-dodecano-bis(L-lle-L-Phe-L-Leu), and 1,12-dodecano-bis(L-Phe-L-Val-L-Leu), etc. adopt most probably a random structure by CD studies. It was found by titration spectrum that an inclusion complex of 1:1 ratio (association constant; azobenzene (guest, Ka=1.0 x 10(4)M-1) is formed between 1,12-dodecano-bis(L.-Phe-L-Phe-L-Leu) and [L0]=1.758 x 10(-5)M-1). Moreover, the stability of the complexes was increased in order of 1,12-dodecano-bis(L-Phe-L-Phe-L-Leu) x azobenzene> 1,12-dodecano-bis(L-Phe-L-Phe-L-Val) x azobenzene> 1,12-dodecano-bis(L-Phe-L-Val-L-Leu) azobenzene. The data show that X-Phe-L-Phe-L-spacer(S)-L-Phe-L-Phe-X (X=amino acids; S = 1,2-ethano- and 1,12-dodecano-) plays an important role as a binding site of the artificial receptor. The hydrophobic interaction of the four Phes in the two strands is a very interesting issue in the physiological action of proteins as well as the conformation of the backbone of X-L-Phe-L-Phe-spacer(S)-iL-Phe-l.-Phe-X.

Amyloid beta-Peptides↗

PubMed2000

[Reactive species responsible for biological actions of photoexcited fullerenes].

Fullerene (C60, C70, etc.) is an effective photosensitizer and its utilization as a pharmacophore for photo-chemotherapy of tumors has received considerable attention. We developed a method to solubilize fullerenes into water with polyvinylpyrrolidone (PVP) as a detergent. By using thus prepared aqueous fullerene solutions, we have clarified a series of biological activities of fullerene under photoirradiation which include DNA-cleavage, hemolysis, mutagenicity, cancer-initiation, and cell-toxicity. A newly synthesized C60 derivative with an acridine moiety as a DNA-chelating function showed much more effective DNA-cleaving activity in the presence of NADH. Visible-light irradiation of PVP-solubilized C60 in water in the presence of NADH as a reductant and molecular oxygen resulted in the formation of O2.-, which was detected by the EPR spin-trapping method. Formation of O2.- was also evidenced by the direct observation of a characteristic signal of O2.- by the use of a low-temperature EPR technique at 77 K. On the other hand, no formation of 1O2 was observed by the use of TEMP as a 1O2 trapping agent. No near-IR luminescence of 1O2 was also observed in the aqueous C60/PVP/O2 system. These results suggest that photoinduced bioactivities of the PVP-solubilized fullerene are caused not by 1O2, but by reduced oxygen species (O2.-, .OH) which are generated by the electron-transfer reaction of C60.- with molecular oxygen.

Animals↗

PubMed2000

[Nitric oxide (NO) donor].

Nitric oxide (NO), which is synthesized from L-arginine by nitric oxide synthase (NOS) in mammals, acts as a signal molecule for vasorelaxation, cytotoxicity and neurotransmission. The difficulty in handling of a gaseous and labile NO causes problems with the effective and precise studies using NO. The increasing interest in the biological roles of NO requires the use of NO donors which releases NO under the various desirable conditions. We systematized the most commonly used NO donors in this article to support the biological investigation. NO donors were classified according to the functional groups based on NO-donating characteristics. The preparation, chemical properties and NO-donating ability of these NO donors are summarized. It is particularly described in some detail on the stability both as a solid and in solution and the handling of the compounds.

Animals↗

PubMed2000

Decolorization of heat-treatment liquor of waste sludge by a bioreactor using polyurethane foam-immobilized white rot fungus equipped with an ultramembrane filtration unit.

A bench-scale bioreactor using immobilized fungal cells equipped with an ultramembrane filtration unit was developed as a means of decolorizing brown color components (melanoidins) arising from the heat-treatment liquor (HTL) of waste sludge. Artificial HTL containing 4200 color units of synthetic melanoidin supplemented with 1000 mg/l ethanol was first subjected to decolorization by the fungus Coriolus hirsutus IFO4917 immobilized onto polyurethane foam cubes. Then, the resultant biologically treated HTL was subjected to ultrafiltration to obtain the permeate (filtrate) as the effluent. The retentate (concentrate) of the filtration unit, containing the remaining melanoidin of high molecular weight and extracellular decolorizing enzymes, was returned to the fungal bioreactor to allow further decolorization. This system was operated in a sequencing batch mode under nonsterile conditions. Contamination of the bioreactor with air/water-born microbes markedly lowered the decolorization efficiency. However, this problem was solved by heating the returned concentrate at 50 degrees C for 10 min. Under the almost stable condition of a hydraulic retention time of 2 d in a 1-d cycle sequencing batch mode, about 70% decolorization was routinely achieved using the entire system (bioreactor + ultrafiltration), while the contribution of the fungal bioreactor alone to the decolorization was about 45%.

Journal Article↗

PubMed1999

Mechanistic studies of catechins as antioxidants against radical oxidation.

The antioxidative mechanisms of catechins were studied by investigating products generated at the first stages by 2, 2'-azobis(2-aminopropane)hydrochloride (AAPH)-induced radical oxidation, without any isolation, using LC/MS, spectrophotometry, and PM3 semiempirical molecular orbital (MO) calculations. Catechins were quite effective in scavenging peroxyl radicals in a liposomal system and in an aqueous system except for (-)-epigallocatechin (EGC). EGC was the least effective among four catechins tested. From the results of LC/MS and spectroscopic studies, (-)-epicatechin (EC) would be gently converted to an anthocyanin-like compound. According to the mechanisms, the compound produced from EC by radical oxidation can also function as an antioxidant. As a result, EC has a longer inhibition period (tinh = 9360 s). On the other hand, EGC decreased shortly after oxidation (tinh = 3420 s) and was transformed to a quinone-like compound. The addition of superoxide dismutase (SOD) reduced the chemiluminescence from EGC during oxidation. Active oxygen including superoxide anion radicals (O-2) may be produced in the case of EGC, but not in the case of EC. However, EGC has a more rapid scavenging effect on peroxyl radicals (kinh/kp = 232) than EC (kinh/kp = 41). The calculated C-H bond dissociation enthalpies (BDEs) for catechins at the C-2 position were unexpectedly low (65 kcal/mol) compared to O-H BDEs at phenolic sites (70 kcal/mol), suggesting that hydrogen at the C-2 position may be abstracted by free radicals. The authors propose the tentative antioxidative mechanisms of catechins depending on the experimental results and theoretical calculations.

Amidines↗

PubMed1999

Determination of 4-hydroxy-2-nonenal in primary rat hepatocyte cultures by liquid chromatography with laser induced fluorescence detection.

An HPLC (high performance liquid chromatography) method with laser induced fluorescence (LIF) detection is described for the determination of 4-hydroxy-2-nonenal (HNE) formed from lipid peroxidation in rat hepatocytes. Carbonyl compounds were fluorescently labelled by incubating the hepatocyte samples with a tagging reagent, 4-(2-carbazoylpyrrolidin-1-yl)-7-nitro-2,1,3-benzoxadiazole (NBD-ProCZ), at 60 degrees C for 10 min. The hydrazone derivatives were extracted with a C18 solid phase extraction (SPE) cartridge and separated on a reversed-phase HPLC column. The detection limit was 2.5 fmol or 0.5 nM (5 microL injection) of HNE in the cell homogenate. Method precision (C.V.) was 5% at the 5 nM level. The method has been used to determine free HNE in rat hepatocyte samples treated with several pro-oxidant toxins. A significant HNE increase (from 4 to 27.6 pmol/10(6) cells) was observed with the samples treated by allyl alcohol. The results were in accordance with those for malondialdehyde formation as measured by a thiobarbituric acid (TBA) assay.

Aldehydes↗

PubMed1999

Scavenging mechanisms of (-)-epigallocatechin gallate and (-)-epicatechin gallate on peroxyl radicals and formation of superoxide during the inhibitory action.

The scavenging effects of (-)-epigallocatechin gallate (EGCG) and (-)-epicatechin gallate (ECG) on peroxyl radicals and their mechanisms were studied by investigating the products formed during the first stages by 2,2'-azobis(2-aminopropane) hydrochloride (AAPH)-induced oxidation, without any isolation, using LC/MS, spectrophotometry, chemiluminescence analyses, and semiempirical molecular orbital (MO) calculations. The results show that EGCG can be converted to an anthocyaninlike compound followed by cleavage of the gallate moiety by oxidation. On the other hand, ECG can be converted to an anthocyaninlike compound after cleavage of the gallate moiety. The calculated C-H bond dissociation enthalpies (BDEs) for EGCG and ECG at the C-2 position were quite low (62.7 and 66.8 kcal/mol, respectively) compared with O-H BDEs at the phenolic sites (ca. 70 kcal/mol), suggesting that the C-2 hydrogen can be abstracted by free radicals. The addition of superoxide dismutase (SOD) decreased the chemiluminescence in EGCG by one-half during the inhibitory action. Active oxygen including superoxide (O2-) would be produced in EGCG, but not in ECG. The authors proposed the antioxidative mechanisms of EGCG and ECG depending on the experimental results and theoretical calculations.

Amidines↗

PubMed1999

The gene search system. A method for efficient detection and rapid molecular identification of genes in Drosophila melanogaster.

We have constructed a P-element-based gene search vector for efficient detection of genes in Drosophila melanogaster. The vector contains two copies of the upstream activating sequence (UAS) enhancer adjacent to a core promoter, one copy near the terminal inverted repeats at each end of the vector, and oriented to direct transcription outward. Genes were detected on the basis of phenotypic changes caused by GAL4-dependent forced expression of vector-flanking DNA, and the transcripts were identified with reverse transcriptase PCR (RT-PCR) using the vector-specific primer and followed by direct sequencing. The system had a greater sensitivity than those already in use for gain-of-function screening: 64% of the vector insertion lines (394/613) showed phenotypes with forced expression of vector-flanking DNA, such as lethality or defects in adult structure. Molecular analysis of 170 randomly selected insertions with forced expression phenotypes revealed that 21% matched the sequences of cloned genes, and 18% matched reported expressed sequence tags (ESTs). Of the insertions in cloned genes, 83% were upstream of the protein-coding region. We discovered two new genes that showed sequence similarity to human genes, Ras-related protein 2 and microsomal glutathione S-transferase. The system can be useful as a tool for the functional mapping of the Drosophila genome.

Amino Acid Sequence↗