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Biomedical subjects

T Horio

Publications and source records attributed to T Horio.

At least 325 records · Page 18Linked to original sources
PubMed1977

Formation of sugar phosphates in colicin K-treated Escherichia coli.

Colicin K greatly decreased the incorporation of 32P-labeled inorganic orthophosphate into nucleotides and nucleic acids, causing a concomitant increase in the formation of 32P-labeled sugar phosphates in sensitive cells of Escherichia coli. These sugar phosphates were formed in aerobically growing cells, as well as in cells under stringent control of ribonucleic acid synthesis. The main 32P-labeled product was identified as sedoheptulose 7-phosphate in two strains (B1 and K-12 MK-1) and fructose 1,6-diphosphate in one strain (K-12 CP78). The formation of sugar phosphates induced by colicin K was inhibited by carbonyl cyanide m-chlorophenylhydrazone. It was also not observed in N,N'-dicyclohexylcarbodiimide-treated cells or Mg2+-(Ca2+)-adenosine triphosphatase-less mutant (strain K-12 AN120) cells. Thus, the formation of sugar phosphates in colicin K-treated cells is dependent on the formation of adenosine 5'-triphosphate by oxidative phosphorylation.

Adenosine Triphosphatases↗
PubMed1976

Pyruvate kinase isozymes in various tissues of rat, and increase of spleen-type pyruvate kinase in liver by injecting chromatins from spleen and tumor.

Pyruvate kinase [EC 2.7.1.40] in various tissues of rats was separable into seven kinds of pI-isozymes by isoelectric separation with Ampholine carrier ampholytes; pI 5.4-isozyme, pI 5.6-isozyme, pI 6.2-isozyme (2 kinds), pI 6.6-isozyme, pI 7.4-isozyme, and pI 7.8-isozyme. Some of these pI-isozymes contained bound fructose 1,6-diphosphate (FDP). The bound FDP was completely dissociated when the pI-isozymes were salted out with ammonium sulfate. In the FDP-free form, pyruvate kinase was classified into three types, liver-type (type L) of pI 6.2, muscle-type (type M) of pI 7.4, and spleen-type (type M2) of pI 7.8. The liver-type isoenzyme had two kinds of FDP-binding sites; the pI 5.6-isozyme and pI 5.4-isozyme were obtained when one and two kinds of sites were bound with FDP, respectively. The association and dissociation of FDP at both sites were reversible in the presence and absence of 0.15 M KC1 (high ionic strength). The muscle-type isoenzyme had no FDP-binding site. The spleen-type isoenzyme had two kinds of FDP-binding sites, like the liver-type isoenzyme. When the ionic strength of solutions containing the enzyme and FDP was sufficiently low, one and two kinds of the sites could bind with FDP, converting the enzyme into pI 6.6-isozyme and pI 6.2-isozyme, respectively. FDP bound with one kind of site (the 2nd site) was easily dissociable, but FDP bound with the other kind of site (the 1st site) was not. Provided that the 1st site carried bound FDP, the 2nd site was associable at high ionic strength. The liver-type isoenzyme free of FDP and the spleen-type isoenzyme bound with FDP at both sites had similar pI values of 6.2 and were not separable by isoelectric separation. Some properties of these pI-isozymes were compared. When Rhodamine sarcoma was transplanted in rats, the content of spleen-type isoenzyme in the livers increased. When rats were injected with chromatin prepared from either Rhodamine sarcoma or spleen, the content of spleen-type isoenzyme in the livers again increased. This was not observed on the injection of chromatin prepared from liver, indicating that the factor capable of controlling the gene expression was present in chromatins of sarcoma and spleen but barely or not at all in chromatin of liver.

Animals↗
PubMed1976

Polarographic studies in presence of Triton X-100 on oxidation-reduction components bound with chromatophores from Rhodospirillum rubrum.

Polarographic studies on oxidation-reduction components bound with chromatophores from Rhodospirillum rubrum were carried out at 24 degrees. 1. Using a carbon-paste electrode as the working electrode, polarographic waves characteristic of oxidation-reduction components were observed in the presence, but not in the absence of Triton X-100; these waves were therefore measured in the presence of the detergent. 2. At least two kinds of oxidation-reduction components were detectable, having different half-wave potentials (E1/2); at pH 7, one had an E1/2 value of +275 mV (POC+275) and the other had a value of +60 mV (POC+60). 3. POC+275 was reduced by succinate and by NADH. Both reductions were almost completely inhibited by antimycin A, which hardly affected the reductions of ubiquinone-10 by succinate and by NADH. Most POC+275 molecules were not reduced by the substrates when quinones were extracted from the chromatophores, and the reductions were mostly restored when ubiquinone-10 was re-added. This indicates that POC+275 is functional between ubiquinone-10 and cytochrome c2 in the electron transport system. 4. POC+60 was reduced by succinate, but hardly at all by NADH. The reduction of POC+60 was not influenced either by the addition of antimycin A or by the extraction of quinones. This suggests that POC+60 is functional in the process from succinate dehydrogenase [EC 1.3.99.1] to ubiquinone-10 in the electron transport system. 5. Of the POC+275 reducible by dithionite, approximately 70% could be reduced in the absence of Triton X-100, provided that the potential of the working electrode immersed in chromatophore suspensions was set at potentials of 0 mV or lower and that the electrochemical reaction was carried out at pH 7.5. When the potential of the electrode was set at +50 mV (the same as the E1/2 value of ubiquinone-10 bound with chromatophores), and the suspension was allowed to stand for various lengths in the presence of the detergent, it was found that approximately half of the electrochemically reducible POC+275 was rapidly reduced, followed by a slow reduction. The discrepancy in the oxidation-reduction equilibrium on the basis of the E1/2 values of ubiquinone-10 and POC+275 is discussed.

Antimycin A↗
PubMed1976

The induction of photocontact sensitivity in guinea pigs without UVB radiation.

Allergic photocontact sensitization could be induced in guinea pigs with 3,3',4',5-tetrachlorosalicylanilide (TCSA), 3,4',5-tribromosalicylanilide (TBS), and bithionol using pretreatment with sodium lauryl sulfate (SLS) and long-wave ultraviolet (UVA) radiation. Mid-wave ultraviolet below 320 nm (UVB) was not necessary for the induction of sensitization. Combined use of SLS pretreatment with UVA radiation resulted in more effective sensitization than combined UVB and UVA radiation. Higher sensitization rates to TCSA and TBS were achieved by allowing rest periods between each of 5 2-hr exposures to UVA than by daily 1-hr exposures for 10 consecutive days. The opposite result was obtained with bithionol. Although UVB has been customarily used in the past for induction of photosensitivity, its role is only to irritate the site of induction.

Animals↗
PubMed1976

The fate of tetrachlorosalicylanilide in photosensitized guinea pigs.

The distribution and fate of 3, 3', 4', 5-tetrachlorosalicylanilide (TCSA) in photosensitized guinea-pig skin following topical application at varying times was investigated by fluorescence microscopy in unfixed, frozen sections. When the site to which TCSA had been applied was irradiated with long-wave UV light, TCSA was detected in the entire epidermis only 3 days after application and in the horny layer up to 10 days. Unless TCSA-treated sites were exposed to light, TCSA was still recognized in the entire epidermis 10 days after application and in the horny layer even at 3 weeks. The irradiated photosensitized guinea pigs in the present study eliminated TCSA more rapidly than normal control animals in our previous work. The mechanism of persistent light reaction was discussed and we concluded that TCSA can remain in the skin for a long time, because it is a prohapten, not a hapten.

Animals↗
PubMed1976

Allergic and photoallergic dermatitis from diphenhydramine.

A 52-year-old man developed contact and photoallergic dermatitis caused by diphenhydramine hydrochloride as well as contact dermatitis from paraphenylenediamine. The diphenhydramine photoallergy was elicited by long-wave ultraviolet light. The action spectrum differs from that noted in a recent report in which wavelengths shorter than 320 nm were responsible for eliciting diphenhydramine photoallergy. To the best of my knowledge, this is the third case of diphenhydramine photosensitivity reported in the English literature. The combination of both contact and photosensitivity to diphenhydramine has not previously been described.

Dermatitis, Contact↗
PubMed1975

Chlorpromazine photoallergy. Coexistence of immediate and delayed type.

A 54-year-old woman had a recurrent pruritic eruption in light-exposed areas. She had a combination of three types of hypersensitivity to chlorpromazine, ie, allergic contact dermatitis, photocontact dermatitis, and immediate allergic photosensitivity. Immediate wheal reactions were found after long-wave ultraviolet light irradiation at photopatch test and intradermal injection sites with chlorpromazine. These responses were differentiated from phototoxic reactions. A positive passive transfer reaction was also observed. To my knowledge, chlorpromazine photosensitivity of the immediate type has not been previously described.

Chlorpromazine↗
PubMed1975

Polarographic studies on ubiquinone-10 and rhodoquinone bound with chromatophores from Rhodospirillum rubrum.

Redox components bound with chromatophores of Rhodospirillum rubrum, and pure samples of ubiquinone-10 and rhodoquinone were studied polarographically at 24 degrees. In a mixture of ethanol and water (4 : 1, v/v) at pH 7, ubiquinone-10 and rhodoquinone had half-wave potentials (E1/2) OF +43 MV and -63 mV, respectively. For both quinones, values of the electron transfer number (n) were 2 , and plots of E1/2 versus pH formed straight lines with slopes of -30 mV/pH in the neutral pH range; thus, values of the proton transfer number (n-a) were estimated to be 1 for both quinones. When bound with chromatophores, ubiquinone-10 and rhodoquinone had E1/2 values of +50 mV (n=2) and -30 mV (n=2), respectively, at pH 7. Values of (n-a) were estimated to be 1 for ubiquinone-10 and 2 for rhodoquinone. A component (POC-170) thought to be one of the active center bacteriochlorophylls (Liac-890) was characterized; it has E1/2 value of -170 mV at pH 7 and its oxidation-reduction is possibly brought about by dehydrogenation-hydrogenation. Conceivably, the oxidation-reduction sites of ubiquinone-10, rhodoquinone and POC-170 partly, if not all, exist on the surface of chromatophore membrane or project outside the membrane, because of their accessibility to the polarographic electrode.

Bacterial Chromatophores↗
PubMed1975

Effects of pH indicators on various activities of chromatophroes of Rhodospirillum rubrum.

1. The effects of pH indicators on activities for ATP hydrolysis in the dark and ATP-Pi exchange in the dark were examined with chromatophores from Rhodospirillum rubrum. Of thirty-one pH indicators tested, eleven (metanil yellow, 2, 4-dinitrophenol, ethyl orange, bromocresol green, resazurin, neutral red, bromthymol blue, alpha-naphtholphthalein, o-cresolphthalein, phenolphthalein, and alizarin yellow G) almost completely inhibited the activities for ATP formation and ATP-Pi exchange at concentrations of 1 mM, and were studied in detail. 2. Of the eleven pH indicators, those other than alpha-naptholphthalein, o-cresolphthalein and phenolphthalein, when assayed at appropriate concentrations, inhibited ATP-Pi exchange, but not ATP hydrolysis. In ATP-Pi exchange, these eight pH indicators at the concentrations described above were competitive against Pi, and non-competitive against ATP. The remaining three kinds of pH indicators were non-competitive against either Pi or ATP, when assayed at concentrations of the dyes that inhibited both activities. 3. The amounts of pH indicators bound with chromatophores were measured. No correlation was found between the amounts of the bound dyes and the extents of their inhibition of either ATP formation or ATP-Pi exchange. 4. Ethyl orange (pKa=4.1) and 2, 4-dinitrophenol (pKa=3.9) stimulated ATP hydrolysis to the greatest extent. The latter dye was hardly bound with chromatophores. 5. The stimulatory effects of pH indicators on ATP hydrolysis were hardly affected by extraction of quinones from chromatophores. 6. Most of the pH indicators stimulated both succinate-cytochrome c2 and NADH-cytochrome c2 reductions in the dark. 7. The mechanism of uncoupling of the electron transfer system and the phosphorylation system by pH indicators and the mechanism of the coupling are discussed.

Adenosine Triphosphate↗
PubMed1975

Effect of injection of nuclear fraction from Rhodamine sarcoma on turnover of liver catalase.

1) When nuclear fraction prepared from Rhodamine sarcoma (sarcoma nuclear fraction) was injected into mice three times every 24 hr, the catalase activity of the liver decreased to one-third of the original activity. 2) By the injection of sarcoma nuclear fraction into mice, the catalase activity with the soluble fraction from homogenates of the liver decreased more significantly than that with the particulate fraction from them. 3) Immunological titration proved that the decrease of catalase activity in the liver of mice injected with sarcoma nuclear fraction was brought about by decrease in the amount of catalase protein. 4) In the mice, whose liver catalase activity had been irreversibly inhibited by injection of 3-amino-1,2,4-triazole, the initial rate for the restoration of the liver catalase activity was significantly showed by further injection of sarcoma nuclear fraction. 5) When the inhibitor of catalase biosynthesis, allylisopropylacetamide, was injected into mice, the activity level of the liver catalase decreased. The extent of decrease by the injection of the inhibitor was slightly lower than that by the injection with sarcoma nuclear fraction, which was almost the same as the extent of decrease by the injection of sarcoma nuclear fraction plus allylisopropylacetamide. 6) It is conceivable that the catalase biosynthesis in the liver was inhibited by the injection of sarcoma nuclear fraction in almost the same manner as by the injection of allylisopropylacetamide. However, it is not certain whether the degradation of liver catalase was slightly stimulated by the injection of sarcoma nuclear fraction.

Allylisopropylacetamide↗
PubMed1975

Role of ubiquinone-10 in electron transport system of chromatophores from Rhodospirillum rubrum.

The role of ubiquinone-10 in the activities for the reduction of free cytochrome c2 and bound cytochrome cc' by succinate was studied with chromatophores from a blue-green mutant (G-9) of Rhodospirillum rubrum. 1. By a single extraction with isooctane, approximately 90% of ubiquinone-10 was easily removed from the chromatophores. In the extracted chromatophores, the activity for succinate-cytochrome c2 reduction decreased to 5-10% of the original activity. This depressed activity was mostly restored by adding ubiquinone-10. The remaining quinone was hardly extractable, even by repeated extractions. With repeatedly extracted chromatophores, the activity for succinate-cytochrome c2 reduction was mostly restored to the same extent as with once-extracted chromatophores, whereas the extent of inhibtion of the activity by antimycin A gradually fell. 2. In isooctane-extracted chromatophores, the activity for the reduction of bound cytochrome cc' by succinate under anaerobic conditions decreased to 35 to 95% of the original level. With chromatophores in which the remaining activity was as low as 40% of the original level, the activity was partially restored by adding ubiquinone-10, but this was not the case with chromatophores in which the remaining activity was higher than approximately 50% of the original level.

Alkanes↗