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Biomedical subjects

H Taguchi

Publications and source records attributed to H Taguchi.

At least 109 records · Page 6Linked to original sources
PubMed1994

Glyceryl-ether monooxygenase (EC 1.14.16.5): nature of the glyceryl-ether lipid substrates in aqueous buffer.

The kinetics of inhibition of glyceryl-ether monooxygenase with 6-methyl-5,6,7,8-tetrahydropterin as cofactor (saturating) by the detergent Mega-10 with batyl alcohol and (RS)-3-(1-hexadecyloxy)-2-hydroxypropane-1-phosphocholine as substrates exhibited noncompetitive inhibition with apparent Ki values of 1.74 +/- 0.37 mM and 185 +/- 23 microM, respectively. Inhibition by octadecan-1-ol (with batyl alcohol as substrate in the presence of 2.3 mM Mega-10) was competitive with an apparent Ki value of 765 +/- 80 microM. The critical micelle concentration values of various solutions of Mega-10 were determined and used to show that the active ether-lipid substrates were in micelle form (for a water soluble substrate) or mixed micelle form (for substrates solubilised with Mega-10).

Animals↗
PubMed1994

[Screening for thyroid dysfunction in adults residing in Hokkaido Japan: in relation to urinary iodide concentration and thyroid autoantibodies].

The prevalence of thyroid dysfunction and its relation to thyroid autoantibodies (TAA) and urinary iodide concentration (UI) was studied in apparently healthy adults in Sapporo (n = 4110) (Sapporo group), and in five coastal areas of Hokkaido (n = 1061) (coastal group) which produce iodine-rich seaweed (kelp). The frequency of above normal UI (high UI) in the morning urinary samples of coastal group was 10.8%, significantly higher than that of Sapporo group (6.4%) (p < 0.001). Frequency of positive TAA in both groups were similar. In Sapporo group TAA was positive in 6.4% of males and 13.8% of females with an age-related increase. The overall prevalence of hyperthyroidism (TSH < 0.15 mU/L) in coastal group (0.6%) was similar to that in Sapporo group (1.1%), while that of hypothyroidism (TSH > 5.0 mU/L) in coastal group (3.8%) was significantly higher than that in Sapporo group (1.3%) (P < 0.001). The frequency of high UI correlated significantly with that of hypothyroidism with negative TAA (r = 0.829, P < 0.05), but not with positive TAA, or with that of hyperthyroidism. Hypothyroidism was more prevalent in TAA negative subjects with high UI than with normal UI. Moreover, serum TSH and thyroglobulin levels were higher and free T4 level was lower in former than in latter group. These results indicate that 1) the prevalence of TAA negative hypothyroidism in iodine sufficient areas may be associated with the amount of iodine ingested, 2) this hypothyroidism is more prevalent and marked in subjects consuming further excess amounts of iodine, and 3) excessive intake of iodine should be considered an etiology of hypothyroidism in addition to chronic thyroiditis in these areas.

Adult↗
PubMed1993

Truncated GroEL monomer has the ability to promote folding of rhodanese without GroES and ATP.

Similar to chaperonins from other sources, intact chaperonin from Escherichia coli (GroEL) exists as a tetradecamer, and the ability to promote folding of other proteins has been considered to be dependent on this oligomeric structure. However, the peptide fragments of GroEL of molecular size 34-50 kDa, which are produced by limited proteolysis of monomeric GroEL and are unable to assemble into an oligomer, retain the ability to promote folding of rhodanese even though the yield of productive folding is lower than the intact GroEL/GroES/ATP system. This promotion by truncated GroEL obeys rapid kinetics and does not require GroES and ATP.

Adenosine Triphosphate↗
PubMed1993

Histidine 296 is essential for the catalysis in Lactobacillus plantarum D-lactate dehydrogenase.

Two His residues, His-205 and His-296, in Lactobacillus plantarum D-lactate dehydrogenase are highly conserved in the D-isomer-specific 2-hydroxyacid dehydrogenase family, suggesting that they are candidates for the catalytic His in the enzyme. The substitution of His-296 with Tyr by means of site-directed mutagenesis induced a drastic decrease in the reaction rate, while a His-205 to Tyr substitution induced no large change in the catalytic properties. In pyruvate reduction, the Tyr-296 enzyme showed a slightly increased Km below pH 6.0 but no significant pH dependence above pH 6.0, where the wild-type enzyme showed an increased Km value. In D-lactate oxidation, in contrast, the Tyr-296 enzyme showed a greatly increased Km value for D-lactate and strong pH dependence. An additional substitution of His-296 with Gln induced more complete loss of the catalytic activity. In contrast to the Tyr-296 enzyme, the Gln-296 enzyme showed a greatly increased Km value and a strong pH-dependent reaction rate even in pyruvate reduction. Unlike the wild-type or His-205 enzyme, both the Tyr-296 and Gln-296 enzymes showed significant resistance against diethyl pyrocarbonate. These results clearly indicate that His-296 is essential for the catalysis by D-lactate dehydrogenase, as in the case of His-195 in L-lactate dehydrogenase.

Amino Acid Sequence↗
PubMed1993

A chaperonin from a thermophilic bacterium, Thermus thermophilus.

Unlike Escherichia coli chaperonins, a chaperonin (cpn) from a thermophilic bacterium, Thermus thermophilus, consisting of homologues to GroEL (cpn 60) and GroES (cpn 10) is co-purified as a large complex. Thermus chaperonin shows a bullet-like shape in the side view seen by electron microscopy, and antibody against cpn 10 binds only to the round side of the bullet. We conclude that a single cpn 60-heptamer ring with two stripes stacks into two layers and a cpn 10 oligomer binds to one side of the layers. The purified Thermus chaperonin contains endogenously bound ADP, and incubation with ATP causes a partial dissociation of chaperonin into cpn 60 monomers and a cpn 10 heptamer. The effect of Thermus chaperonin on protein refolding upon dilution from guanidine HC1 is different at three temperature ranges. At high temperatures above 55 degrees C, where the native proteins are stable but their spontaneous foldings fail, the chaperonin induces productive folding in an ATP-dependent manner. At middle temperatures (25-55 degrees C) where spontaneous foldings of the enzymes occur, the chaperonin slows down the rate of folding without changing the final yield of productive folding. At lower temperatures below 25 degrees C where spontaneous foldings also occur, the chaperonin arrests the folding even in the presence of ATP. When a solution of relatively heat labile protein is incubated at high temperatures, and then residual activity of the protein is measured at its optimal temperature after incubation with ATP, the temperature that causes irreversible heat denaturation of the protein is elevated about 10 degrees C by inclusion of Thermus chaperonin in the solution.(ABSTRACT TRUNCATED AT 250 WORDS)

3-Isopropylmalate Dehydrogenase↗
PubMed1993

Chaperonin from Thermus thermophilus can protect several enzymes from irreversible heat denaturation by capturing denaturation intermediate.

Chaperonin isolated from Thermus thermophilus is stable up to 80 degrees C. Taking advantage of this heat stability, we have studied the effects of chaperonin on heat denaturation of several relatively heat labile enzymes. When the enzymes are incubated at their denaturating temperatures, the presence of T. thermophilus chaperonin in the solution has little effect on the rate of apparent inactivation of the enzyme. However, this inactivation is not irreversible since most activity is recovered when the solution is shifted to the second incubation at a moderate temperature with concomitant addition of MgATP. When the chaperonin is omitted from the solution, no recovery is observed. Recovery of the activity is also dependent on MgATP in the second incubation and 50% of recovery is attained at 5 microM MgATP. When the chaperonin is added after starting the incubation at a denaturing temperature, recovery of the activity becomes poorer as the delay of chaperonin addition increases. The critical temperature of the incubation at which irreversible denaturation occurs to the enzymes is elevated 8-15 degrees C by inclusion of T. thermophilus chaperonin in the solution. The heat stability of captured proteins by the chaperonin, assessed as retention of the ability to resume productive folding under optimal conditions, is measured more accurately using chemically produced folding intermediate-chaperonin complexes. The ability is lost at about 78 degrees C being irrespective of variable heat stability of individual enzymes. These results indicate that during heat denaturation proteins assume a common structure which is recognizable by the chaperonin. Once a protein with this structure is captured by T. thermophilus chaperonin, it retains the ability to resume productive folding even after exposure to the otherwise denaturing high temperature. Its heat stability seems to be limited solely by heat stability of chaperonin.

Adenosine Triphosphate↗
PubMed1993

Central nervous system involvement of adult T-cell leukemia-lymphoma with multinucleated giant cells in the brain, skin, and kidney.

BACKGROUND: A case of central nervous system (CNS) involvement in a patient with adult T-cell leukemia-lymphoma (ATLL) with multinucleated giant cells (MNGC) is presented. METHODS: A 48-year-old woman with human T-lymphotropic virus type I (HTLV-I) antibody titer had multiple focal brain symptoms and skin eruptions without lymphadenopathy, hepatosplenomegaly, or increased abnormal lymphocytes in the peripheral blood. No spastic paraparesis of the lower limbs was found. The encephalopathy was progressive, and she died 5 months later despite repeated intrathecal administration of methotrexate, cytosine arabinoside, and prednisolone and monthly systemic chemotherapy with doxorubicin, cyclophosphamide, vincristine, and prednisolone. RESULTS: Postmortem examinations identified unusual ATLL lesions composed of marked infiltrations of atypical mononuclear cells and bizarre MNGC with histiocytic granulomatous reactions in the leptomeninges, brain tissues along the Virchow-Robin spaces, skin, and kidney. Immunohistochemical stains confirmed the T-cell nature of such mononuclear cells and partially T-cell and partially macrophage nature of the MNGC, although no evidence of HTLV-I expression was found. CONCLUSIONS: ATLL presenting with CNS symptoms is rare. It was assumed that the direct cytopathic effects of HTLV-I were responsible for the formation of the MNGC after considering the similarity with MNGC in encephalopathy caused by the human immunodeficiency virus.

Brain↗
PubMed1993

Zymobacter palmae gen. nov., sp. nov., a new ethanol-fermenting peritrichous bacterium isolated from palm sap.

Zymobacter palmae gen. nov., sp. nov. was proposed for a new ethanol-fermenting bacterium that was isolated from palm sap in Okinawa Prefecture, Japan. The bacterium is gram-negative, facultatively anaerobic, catalase-positive, oxidase-negative, nonsporeforming and peritrichously flagellated. It requires nicotinic acid for growth. It ferments hexoses, alpha-linked di- and tri-saccharides, and sugar alcohols (fructose, galactose, glucose, mannose, maltose, melibiose, saccharose, raffinose, mannitol and sorbitol). Fifteen percent of maltose in broth medium is effectively fermented, whereas glucose with a concentration higher than 10% delayed growth initiation and decreased growth rates. Maltose is fermented to produce ethanol and CO2 with a trace amount of acids. Approximately 2 mol of ethanol are produced from 1 mol moiety of hexose of maltose. The organism possesses ubiquinone-9. The G + C content of the DNA is 55.8 +/- 0.4 mol%. Major cellular fatty acids were palmitic and oleic acids and cyclopropanic acid of C19:0. Characteristic hydroxylated acid was 3-hydroxy dodecanoic acid. The bacterium is distinct from other ethanol-fermenting bacteria belonging to the genera Zymomonas Kluyver and van Niel 1936 and Saccharobacter Yaping et al. 1990 with respect to chemotaxonomic and other phenotypic characters to warrant to compose a new genus and a new species. The type strain is strain T109 (= IAM 14233).

Base Sequence↗
PubMed1993

The isolation of Cryptococcus neoformans from pigeon droppings and serotyping of naturally and clinically sourced isolates in China.

This is the first report on the isolation of Cryptococcus neoformans from pigeon droppings in China and their serotypes. C. neoformans colonies which produced brown colonies on caffeic acid-cornmeal agar were found in Twenty-five out of thirty-six samples of pigeon droppings. Fifty-one colonies randomly picked from the positive samples were identified as C. neoformans by a commercially available kit for carbon source assimilation test and Christensen's urea agar. Forty (78%) out of the 51 strains were serotyped as A and 11 (22%) as AD. At the same time, seventeen out of nineteen clinical isolates were serotyped as A and 2 as B. There are three findings in our results. One is that only C. neoformans var. neoformans strains could be isolated from pigeon droppings, although the variety gattii strains were found in the clinical isolates obtained in the same geographic site in China. The second is that serotype A strains were most frequently seen in natural and clinical materials in the southeast part of China, and serotype AD strains were isolated in pigeon droppings but not in clinical materials. The third is that the coexistence of serotype A and AD cells of C. neoformans strains in same samples of pigeon droppings were observed.

Animals↗
PubMed1993

Thallium-201 scintigraphy in the evaluation of thyroid nodules. A retrospective study of 246 cases.

There is controversy at present concerning the value of Tl-201 scintigraphy in the diagnosis of malignant thyroid nodules. The usefulness of Tl-201 scintigraphy in differentiating benign from malignant nodules was evaluated retrospectively. Tl-201 scintigraphy was performed in 101 patients with malignant thyroid nodules and in 145 with benign nodules. Early and late images were examined to compare Tl-201 uptake in nodules and normal thyroid tissue. The visual method resulted in 74% of sensitivity and 58% of specificity for the detection of malignant nodules including incidental cancers. Excluding incidental cancers, 87% sensitivity and 58% specificity were achieved. Small cancers, including incidental cancers less than 1.5 cm in diameter and small number of viable tumor cells in a large tumor also gave negative Tl-201 scintigraphic results. Forty-two percent of the benign lesions gave false positive Tl-201 scintigraphic results. It is concluded that Tl-201 scintigraphy is a sensitive and useful method to use in diagnosing malignant thyroid nodules, but is not a specific method even with late scan, for the detection of malignant thyroid nodules.

Adenocarcinoma, Follicular↗
PubMed1993

Effect of Pinellia ternata tuber on the efferent activity of the gastric vagus nerve in the rat.

Effect of intraduodenal infusion with the hot aqueous extract of Pinellia ternata tuber on the efferent discharges in the gastric branch of the vagus nerve was observed in the anesthetized rat. The infusion of the extract in doses of 2-15O mg per animal (c.a. 300 g, b.wt.) resulted in a dose-related increase in efferent activity of the vagal gastric nerve. The enhancement of the nerve activity following administration of 150 mg of this substance lasted longer than 90 min. It was observed that the suppressive effect on vagal gastric activity due to apomorphine and copper sulfate was antagonized by prior administration of the extract. From these observations it is suggested that Pinellia tuber acts as a facilitatory agent on gastric function.

Animals↗
PubMed1993

The role of the diurnal variation of urinary pH in determining stone compositions.

The diurnal variation of urinary pH and urinary excretion of stone-forming constituents were investigated on 79 stone patients. Composition of the stones was analyzed by means of infrared spectrophotometry. In uric acid stone patients urinary pH was low during the 24-hour period. In mixed calcium oxalate-calcium phosphate stone patients urinary pH was low in the early morning but high in the daytime and at night. In magnesium ammonium phosphate stone patients urinary pH was high throughout the entire day. On the other hand, urinary excretion of calcium was high in the mixed calcium oxalate-calcium phosphate stone patients and low in uric acid or magnesium ammonium phosphate stone patients. These findings suggested that the diurnal variation of urinary pH and urinary excretion of calcium might have an important role in determining stone composition.

Adult↗
PubMed1993

Pyridoxine toxicity to cultured fibroblasts caused by near-ultraviolet light.

Pyridoxine, like riboflavin, has absorption in the range of near ultraviolet (UVA; 320-400 nm) radiation and is known to decompose after long irradiation with germicidal lamps. Thus, the possibility of UVA-induced pyridoxine photosensitization was studied in cultured normal human, hydroa vacciniforme, and xeroderma pigmentosum fibroblasts. Cytotoxicity caused by the sensitization was measured by post-UVA colony formation. Pyridoxine showed strong cytotoxic effect after UVA radiation and the effect remained for at least 60 min after UVA radiation. Although the cytotoxicity decreased a little when pyridoxine was irradiated under anaerobic conditions, the amount of hydrogen peroxide produced by UVA radiation was hardly cytotoxic and the rate of photodecomposition of pyridoxine was slower under anaerobic conditions than aerobic ones. Thus, the toxicity seemed to depend mostly on the photoproducts of pyridoxine. The UVA-induced pyridoxine cytotoxicity was not due to DNA damage that is to be excision-repaired because group A and C xeroderma pigmentosum fibroblasts were killed as in the case of normal human fibroblasts.

Absorption↗
PubMed1993

Neutralizing antibody to vesicular stomatitis virus (HTLV-I) pseudotype in infants born to seropositive mothers.

Breast feeding is the major route of mother-to-child transmission of human T-cell leukemia virus type I (HTLV-I). Our experiments with rabbits have shown that passive immunization is capable of blocking cell-to-cell infection of HTLV-I by blood transfusion or breast feeding. In this study, sera were collected serially from 3 infants born to seropositive mothers and were tested for the presence of neutralizing antibody to vesicular stomatitis virus (HTLV-I) pseudotype as well as antibodies to viral structural proteins. There was a good correlation between neutralizing and viral antibody titers, both of which were detectable until 3-6 months after birth. Whether maternally transmitted neutralizing antibody is protective against perinatal infection of HTLV-I remains to be studied.

Adult↗