A sample of [³H] tobrarnycin (, 000 Ci/Mole) has been synthetized and incubated with
the bacterial ribosome and its subunits. The results obtained show that this antibiotic has
two types of binding sites. The primary one is probably responsible for the inhibition of
protein synthesis whereas the secondary one is probably related to the misreading and reading
tiirough of the messenger RNA.

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(³H) Tobramycin was used as a probe to determine the relationship between the structure of aminoglycoside antibiotics and their ability to remove this drug from its higher affinity binding site on the ribosome. The dissacharide moieties (neamine, tobramine, gentamine) appeared to have a common binding site, whereas the kanosamine, garosamine and ribose moieties determined the specificity of this binding. Amikacin and butikacin behaved in an anomalous manner in spite of their close structural relationship to tobramycin.

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The activities of tobramycin derivatives acetylated and ethylated on the 6'-N, '-N and 3-N positions were examined. The MICs of these derivatives against tobramycin sensitive strains indicated that '-N-ethylated and 6'-N-ethylated derivatives have a fairly good activity, and confirmed that the 3-N position is the most important one for antibiotic activity since 3-N derivatives were less active. The MICs of these derivatives against tobramycin resistant strains, and their inactivation by tobramycin modifying enzymes were examined. These results showed that '-N or 6'-N ethylation protects the drug against inactivation by AAC(') or AAC(6'), respectively, and '-N-ethyltobramycin and 6'-N-ethyltobramycin were active against strains containing these modifying enzymes. On the other hand, 3-N ethylation protects the drug against inactivation by AAC(3) but 3-N-ethyl tobramycin does not inhibit strains containing this enzyme.

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Serotonin receptor (-HTCR) mRNA receives editing at nucleotide positions (sites A – ) located in the sequence encoding the second intracellular loop of -HTCR. -HTCR mRNA without editing and with editing at sites , ABD, ABC, ABCD, and are translated to 6 isoforms of -HTCR: INI(non-edited), VNI(), VNV(ABD), VSI(ABC), VSV(ABCD), and ISI(), respectively. In this study, we investigated electrophysiologically the ability of these isoforms to couple with the G protein / phospholipase (PLC) system using Xenopus oocytes injected with edited -HTCR RNAs and muscarinic M₁ receptor (M1R) RNA. The efficacy with which -HT stimulated each isoform was calculated by comparing -HT–induced current with 100 μM acetylcholine–induced M1R current. Stimulation with -HT of INI(non-edited), VNI(), VNV(ABD), VSI(ABC), VSV(ABCD), and ISI() expressed in Xenopus oocytes showed concentration-dependent responses with EC₅₀ values of .6, 17., 76,, .0, 91., and 20.3 nM, respectively. No significant difference in the ability of -HT to induce currents among the oocytes expressing these isoforms was detected, but in the oocytes expressing VSI(ABC) or VSV(ABCD), -HT had a significantly reduced ability to induce currents. These results suggest that editing at site together with sites A and and/or D markedly reduces -HTCR function by generating isoforms with reduced ability to activate PLC.

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A comparative study of the static and dynamic response of a slope is carried out, using the large deformation theory of the updated Lagrangian formulation and the conventional infinitesimal theory. In the static analysis, a strength reduction method proposed by one of the authors is used to evaluate the safety factor of the slope. It is found that by the large deformation theory, the safety factor is larger than that calculated by the infinitesimal theory, and this difference becomes large along with the reduction of elastic modulus. In the dynamic analysis, it is observed that the large deformation theory gives smaller sliding displacement and larger response acceleration than the infinitesimal approach. It is concluded that in many cases the large deformation approach gives more adequate solutions.

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The ability of Climacodon septentrionalis to immobilize and kill a mycophagous nematode (Aphelenchoides sp.) in vitro is described for the first time. Two isolates produced droplets (20–45 μm in diameter) that formed at the apices of tall, stalked, and branching secretory cells (700–1,500 μm tall). On

% modified malt extract agar, nematodes became enveloped in the droplets, which restricted their ability to move and resulted in complete immobilization and death within several hours of contact. The rate of decomposition of the nematodes varied considerably, with most individuals persisting for weeks whereas others were degraded within several days and appeared to be colonized by dense hyphal growth. This study provides the first documentation of a non-agaricoid fungus producing secretory cells that are able to immobilize nematodes.

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Leakage of water due to internal erosion through a dam body or foundation is a major problem with fill-type dams. Recent case histories and research suggest that most cases of internal erosion are possibly triggered by hydraulic fracturing. However, the quantitative mechanism of hydraulic fracturing still remains to be solved. Therefore in-situ hydraulic fracture tests were carried out with a cheap, concise apparatus using boreholes dug in the soft clayey volcanic soil foundation of a low earth dam (Oyachi Dam) in Niigata Prefecture. Water was injected into the foundation through a perforated pipe by two methods : one was under a controlled injection pressure and the other was a controlled injection flow rate. In the former method, the relationship between flow rate and injection pressure was observed and it was found that a yield pressure or fracture pressure existed in all the tests. By repeating the injection test it was confirmed that once a crack is developed, it is very easily reopened by a water pressure a little higher than the earth pressure exerted on the crack. In the latter method, the relationship between injection pressure and time was observed and it was found that fracture pressure varied with flow rate. The boreholes were excavated to observe the development of fracture cracks and it was also found that the cracks had developed perpendicular to the borehole periphery, which means that fracture cracks were induced by tensile stress and denies the explanation that fractures are caused by shear failure.

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A full account is given of the chemical behavior observed for 7, 9-dialkyladeninium salts (16). On treatment with boiling 1N aqueous NaOH for 60min, 16a, , d, (X=I), 16 (X=Br), and 16f (X=ClO₄) rearranged to isomeric N⁶, 7-dialkyladenines (21a-f) in 50-91% yields. Treatment of the salts with 0.N aqueous at room temperature for 30-90min or with Amberlite CG-400 (OH^-) in at room temperature gave the ring-opened derivatives a-f (in the trans-formamide form) in 56-83% yields, and rate constants for the ring-opening reactions of 16a, , d-g (X=ClO₄) and 16 (X=Br) leading to a-g were determined in at pH 9. and ionic strength 0.50 at 25°. Cyclization of a with NaH in at room temperature or with boiling 1N aqueous NaOH produced 21a in % or 72% yield, respectively.In solution, the trans-formamides seemed to transform slowly into the cis-formamides 23, attaining equilibria. The existence of such an equilibrium in or -d₆ at 25° or in at pH 9. and ionic strength 0.50 at 25° was kinetically confirmed in the case of a, and the mechanism of the rearrangement of 16 to 21 through is discussed on the basis of the above kinetic results and Deslongchamps' theory of stereoelectronic control. On treatment with NaBH₄ in MeOH at room temperature, 16a (X=I) furnished the 7, -dihydro derivative 28 (% yield), which slowly decomposed in at 60° to give a in 49% yield.The 7, 9-dialkyladeninium salts (16) were found to be obtainable from N'-alkoxy-1-alkyl--formamidoimidazole-4-carboxamidines (9) through an alternative synthetic route : Alkylations of 9 with alkyl halides in in the absence of base, followed by hydrogenolysis of the N'-alkoxy group and cyclizatio (or vice versa) produced 16 in acceptable yields. In order to interpret the proton nuclear magnetic resonance spectrum of a, the -deuterated species 26 was also synthesized from 24 via 25 and 27.

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Based on the concept "intermediate soil wedge" which is dependent on mobilized frictional resistance, a new theory has been developed for evaluating the seismic earth pressures against retaining walls under any condition between the active and passive states. For this theory, the seismic earth pressure is separated into four components according to their formation. New equations are proposed to determine the distribution, resultant and point of application for each component. An equivalent seismic coefficient is introduced to take into account non-uniform seismic acceleration distribution with depth. The equations place special emphasis on dependence of the seismic earth pressure on mode and level of wall movement. The equations can be reduced to the Mononobe-Okabe equation for the limiting conditions. Their applicability was confirmed by comparing the predictions with a number of previous model test results.

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A finite element model capable of taking into account nonlinear hysteretic soil behavior is presented to study earthquake induced retaining wall movement. The model also accounts for increase in lateral stresses and settlement associated with grain slip caused by cyclic loads. The predictive capability of the proposed method is verified by comparing responses given by the model with those computed by another existing finite element model and also with responses recorded at the Cambridge centrifuge facility. The study reveals that the wall displacement can be substantially affected, among other factors, by the increase in lateral stresses due to grain slip and wall-soil friction. Care should be taken when selecting a constant value of wall-soil friction angle for the entire duration of excitation since structural changes can occur in the soil adjacent to the wall.

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The effects of the pressure of ambient gas and sample temperature on photo-acoustic displacement (PAD) were studied quantitatively using an extremely sensitive laser interferometric probe. For silicon, the PAD signal measured at atmospheric pressure increased by about 18% as compared to that obtained in a vacuum, and varied by less than 0.7% for a change in pressure of % around 1 atm. This effect was attributed to the decrease in refractive index of the gas adjacent to the sample. Temperature rise caused PAD to increase proportionally, and for GaAs, PAD varied 0.4% per degree. The variation of PAD with temperature was accurately explained by the temperature dependence of thermal expansion coefficient and thermal conductivity of the sample.

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(±)-De--Cholestan-9-one (1) and (±)-De--Cholest-(14), -diene-9-one () were prepared as a synthetic precursor for various steroids. In the Synthesis of 1 three important reactions are involved. The first one is the highly stereoselective Claisen rearrangement of the allyl alcohol 9 to introduce the trans stereo-chemistry between (13)methyl and (14)hydrogen and the geometry of 17(20)-olefin. The second one is an efficient intramolecular alkylation of (9)acyl carbanion to construct steroidal -ring. The third one is the stereospecific alkylation (SN) of the secondary tosylate by the protected cyanohydrin 16 to introduce the asymmetric center at (20). These overall transformations provide the required stereochemistry at (13), (14), (17) and (20) in 1. The key reaction in the synthesis of was a highly stereo-selective Michael addition of the organocopper reagent 28 in which (23)allyl alcohol moiety serves to control the stereochemistry at (17) and (13) (cis-stereochemistry between (13)methyl and (17) side-chain). (20)methyl was introduced stereoselectively by combination of Claisen rearrangement and decarbonylation. The stereoselectivity of the Michael addition reaction was, moreover, examined under various conditions.

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