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T Horio

Publications and source records attributed to T Horio.

At least 379 records · Page 21Linked to original sources
PubMed1966

Synthesis and possible character of a high-energy intermediate in bacterial photophosphorylation.

1. In photophosphorylation with chromatophores from Rhodospirillum rubrum, evidence is presented for the synthesis of activated precursors of ATP in the energy-conversion system coupled to photosynthetic electron transport. 2. A significant amount of ATP is synthesized when a reaction mixture containing chromatophores and ADP is illuminated and then incubated with P(i) in the dark. ATP is not synthesized to an appreciable extent, either when a reaction mixture containing chromatophores and P(i) is illuminated and then incubated with ADP in the dark, or when one containing chromatophores alone is illuminated and then incubated with ADP and P(i) in the dark. The amount of ATP thus synthesized is influenced markedly by concentrations of ADP. 3. The chromatophores illuminated with ADP, if allowed to stand in the dark at 30 degrees , gradually lose the ability to form ATP with P(i) in the dark. No loss of the ability occurs when the chromatophores illuminated with ADP are allowed to stand in the dark at 13 degrees or in a frozen state. 4. Mg(2+) is absolutely required for chromatophores to form ATP in the dark after illumination in the presence of ADP, and for the chromatophores to achieve ATP formation with P(i) in the dark. 5. Antimycin A, 2-heptyl-4-hydroxyquinoline N-oxide and o-phenanthroline strongly inhibit the light-dependent acquisition of the ability to form ATP with P(i) in the dark, but not the consequent ATP formation with P(i) in the dark. Arsenate, 2,4-dinitrophenol, quinacrine hydrochloride, quinine hydrochloride and pyrophosphate inhibit the former or the latter, or both. Oligomycin inhibits the former somewhat more than the latter. 6. From these findings it is suggested that a high-energy intermediate is formed in photosynthetic ATP formation, and that its formation is dependent on ADP but not P(i).

Adenine Nucleotides↗
PubMedDate not supplied

Visualization of the dynamic instability of individual microtubules by dark-field microscopy.

It has previously been shown that two populations of microtubules coexist in a dynamically unstable manner in vitro: those in one population elongate while those in the other shorten and finally disappear. This conclusion was based on changes in the number and length distribution of microtubules after dilution of the microtubule solution. Here, we demonstrate directly that growing and shortening populations coexist in steady-state conditions, by visualization of the dynamic behaviour of individual microtubules in vitro by dark-field microscopy. Real-time video recording reveals that both ends of a microtubule exist in either the growing or the shortening phase and alternate quite frequently between the two phases in a stochastic manner. Moreover, growing and shortening ends can coexist on a single microtubule, one end continuing to grow simultaneously with shortening at the other end. We find no correlation in the phase conversion either among individual microtubules or between the two ends of a single microtubule. The two ends of any given microtubule have remarkably different characteristics; the active end grows faster, alternates in phase more frequently and fluctuates in length to a greater extent than the inactive end. Microtubule-associated proteins (MAPs) suppress the phase conversion and stabilize microtubules in the growing phase.

Animals↗
PubMedDate not supplied

Photoallergic reaction. Classification and pathogenesis.

In the present article, an attempt was made to classify photoallergic reactions. Theoretically, they can be divided into four types, based on the origin of photoallergens and on the type of allergy. The photoallergen may be endogenous or exogenous in origin and photoallergic reaction may be immediate or delayed in nature. Lichen planus-like photosensitivity reaction was classified as another type of photoallergy because clinical features are distinct from the other four types. Pathogenic mechanisms were also discussed in each type of reaction, reviewing experimental evidences and speculative concepts of my own and other investigators.

Animals↗
PubMedDate not supplied

Xeroderma pigmentosum variant associated with multiple cancers.

A 62-year-old Japanese man with xeroderma pigmentosum (XP) variant is reported. The patient had developed at least 6 basal cell carcinomas, a squamous cell carcinoma, and a malignant melanoma on sun-exposed areas, and an atypical carcinoid on the right lung. In vivo phototesting showed a normal response. The minimal erythema dose of ultraviolet B (UVB) was not lowered and no delayed peaking of the erythema reaction was observed. His skin fibroblasts exhibited higher sensitivity to UV irradiation, but a normal level of unscheduled DNA and RNA synthesis. Cell fusions with XP group A, C, D, E, F, and G cells after UV irradiation were all complemented. Previous reports together with this case suggest that older XP variant patients have a high frequency of not only skin cancers, but also internal malignancies.

Carcinoid Tumor↗
PubMedDate not supplied

Release mechanism of endothelin-1 and big endothelin-1 after stimulation with thrombin in cultured porcine endothelial cells.

Cultured porcine endothelial cells (EC) released immunoreactive endothelin-1 (ir-endothelin-1) and big endothelin-1 (ir-big endothelin-1) into the medium in a time-dependent way. Reverse-phase high-pressure liquid chromatography coupled with radioimmunoassay showed that the major component of ir-endothelin-1 corresponded to standard endothelin-1 (1-21) and that the major component of ir-big endothelin-1 corresponded to standard big endothelin-1 (porcine 1-39). This release was strongly inhibited by cycloheximide and was, therefore, related to de novo protein synthesis. The release of greater amounts was stimulated by thrombin. The protein kinase C (PKC) inhibitors from two chemical classes, H7 and staurosporine, inhibited release following such stimulation in a relatively dose-dependent way. Neither H7 nor staurosporine affected the basal release of both endothelin-1 and big endothelin-1. Phorbol myristate acetate, which activates PKC and the Ca2+ ionophore A23187, stimulated the release of ir-endothelin-1 and ir-big endothelin-1 in a dose-dependent way, respectively. In addition, the combination of both compounds had a synergistic effect. An inactive enantiomer of phorbol ester, 4 alpha-phorbol-12,13-didecanoate had no effect on the release of ir-endothelin-1 and ir-big endothelin-1. These results suggest that cultured EC release endothelin-1 and big endothelin-1 simultaneously, and that thrombin stimulates this release by a mechanism that probably involves intracellular Ca2+ mobilization and the activation of PKC.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMedDate not supplied

Sensitivity of Staphylococcus aureus, isolated from skin infections in 1994, to 19 antimicrobial agents.

The most common pathogen causing skin infections is Staphylococcus aureus and the incidence of multiply resistant strains of S. aureus has been increasing. The in vitro susceptibility of 130 isolates of S. aureus to 19 antimicrobial agents: ampicillin (ABPC), methicillin, cefaclor, cefpodoxime proxetil, gentamicin, erythromycin, clindamycin, minocycline, vancomycin, fusidic acid, norfloxacin, ofloxacin, enoxacin, ciprofloxacin, lomefloxacin, tosufloxacin, sparfloxacin, nadifloxacin and grepafloxacin, was evaluated by agar dilution tests. The S. aureus isolates were isolated from 130 patients with skin infections in 1994. The proportion of methicillin-resistant S. aureus isolates among the strains isolated was 19.2%. The concentration needed to inhibit 50% of the isolates was 3.13 mg/ml or less for all of the drugs, but the concentration needed to inhibit 90% of isolates was over 12.5 micrograms/ml, except in the cases of minocycline, vancomycin, fusidic acid, tosufloxacin and nadifloxacin. Tosufloxacin and nadifloxacin had the lowest minimum inhibitory concentrations. None of the S. aureus strains was resistant to nadifloxacin.

Anti-Bacterial Agents↗