556 research outputs found
Lick Observatory Belletin, n° 102. — Preliminary note on some simplifications in the reduction of stellar photographs, by C.-D. Perrine
No full textLick Observatory Belletin, n° 102. — Preliminary note on some simplifications in the reduction of stellar photographs, by C.-D. Perrine. In: Bulletin astronomique, tome 24, 1907. p. 199
Sequence-selective binding to DNA of bis/amidinophanoxy/alkanes related to propamidine and pentamidine
No full textA facile synthesis of new beta-lactams
No full textSeveral new beta-lactams have been synthesized in good yields, via the cyclization of 3-chloro-N-arylpropionamides in a mixture of N,N-dimethylformamide and anhydrous sodium carbonate under a nitrogen atmosphere
In vivo inhibition of nitric oxide synthesis by bisisothiouronium and bisguanidinium salts
No full textAbstract
The ability of two S,S'-(alkane-1,ω-diyl) bisisothiouronium dibromides, three N,N'-(alkane-1,ω-diyl) bis guanidinium dinitrates and N,N'-bis (3-guanidinopropyl)piperazine dinitrate to inhibit constitutive (i.e. endothelial and neuronal forms) and inducible forms of nitric oxide synthases has been evaluated in vivo. These compounds, synthesized by two of us (J.C.L. and C.S.), have been tested in vivo; they were administered simultaneously with an irritant (carrageenan λ) into the pleural cavity. The amount of nitrites collected 0.5 and 7 hours after this injection can be considered as an indicator of nitric oxide (NO) production. According to previous data, the first harvesting time can be related to activation of constitutive NO synthases and the second to activation of inducible NO synthases. These substances significantly inhibited nitrite production as did 2-methyl-2-thiopseudourea sulphate, previously described as a potent inhibitor of NO synthases and considered as the reference compound. The inhibiting effect varied according to the chemical structure of the compounds. Results were significantly different from controls at 0.5 h only with the S,S'-(octane-1,8-diyl) bisisothiouronium dibromide and the S,S'(nonane-1,9-diyl) bisisothiouronium dibromide at the highest concentration, N,N'-(heptane-1,7-diyl) bisguanidinium dinitrate and N,N'-bis (3-guanidinopropyl)piperazine dinitrate. At 7 h, all the results were significantly different from controls, with a major effect observed with N,N'-(heptane-1,7-diyl) bisguanidinium dinitrate. The most active substances exerted similar effects to the reference substance
Efficient Synthesis of New Beta-lactams
No full textThe synthesis of beta-lactams was carried out by N-arylpropionamide cyclisation in a mixture of N,N-dimethylformamide and anhydrous sodium carbonate under nitrogen atmosphere with 50 to 90% yield
Amebicidal Efficiencies of Various Diamidines Against 2 Strains of Acanthamoeba-polyphaga
No full textThe first medical cure of Acanthamoeba keratitis was obtained by use of propamidine isethionate. Since then, it has been the basic drug recommended for use in treatment. Because some Acanthamoeba strains have been reported to be resistant to propamidine and propamidine was found to be only weakly cysticidal, superior homologs such as butamidine, pentamidine, hexamidine, heptamidine, octamidine, and nonamidine were tested for their amoebicidal effects on two Acanthamoeba strains isolated from patients with keratitis. Trophozoicidal and cysticidal efficiencies were found to be increased from propamidine to nonamidine; i,e,, when the alkyl chain connecting the two benzene rings in their molecular structures was elongated, in comparison with propamidine, hexamidine and octamidine were the most amoebicidal molecules. As a result of these data, a kinetic study carried out on propamidine, hexamidine, and octamidine demonstrated that the amoebicidal effects resulted from two events: the diffusion of molecules through the plasma membrane or the double wall of trophozoites or cysts, respectively, and the lethal effects of molecules on amoebic protoplasm. The diffusion kinetics were increased when the alkyl chain was elongated, i.e., with an increase in the lipophilic properties of molecules, In contrast, the lethal effect kinetics were found to be unchanged by this elongation, indicating that they originated from the cationic surface-active properties induced by the protonated amidine groups attached to each benzene ring, which themselves remained unchanged from one molecule to the other. These results strongly advocate the immediate replacement of propamidine by hexamidine in the medical treatment of Acanthamoeba keratitis; in France, 0.1% hexamidine eyedrops are available (Desomedine). The results also advocate clinical investigations on the efficiency and toxicity of octamidine, which appears to be the most amoebicidal diamidine in vitro
Utilisation de 4-4'-diamidino-diphenoxyalcanes dans le traitement de la Keratite Amibienne a Acanthamoeba
No full textPerrine, C. D., 1937
No full textContains documents from Tombaugh's tenure on the Observatory staff, 1929-1945, as well as a small amount of material relating to later projects that Tombaugh worked on at Lowell Observatory in the 1950s
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