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At least 415 records · Page 23Linked to original sources
PubMed1989

Do inert beta-lactamase inhibitors act as synergizers of beta-lactam antibiotics? Utility of boric and boronic acids.

Boric and boronic acids were used as inhibitors of beta-lactamases produced by two Citrobacter diversus strains and by one strain of Pseudomonas aeruginosa; all strains were clinical isolates. The beta-lactamases produced by the two Citrobacter diversus strains were inhibited by both borates and boronates, using cephazolin as substrate. The enzyme from Pseudomonas aeruginosa was inhibited only by boronates, using benzylpenicillin as substrate. These inhibitors were also used in combination with selected beta-lactams so as to determine if a synergism of antimicrobial activity occurred. All data reported in the present paper indicate that the minimum inhibitory concentration (MIC) values were lowered in the presence of these inhibitors for the two Citrobacter diversus strains. In the Pseudomonas aeruginosa strains the MIC values were not significantly altered, thus indicating the presence of a permeability barrier for 3-aminophenylboronic acid.

Anti-Bacterial Agents↗
PubMed1988

Responses of the L5178Y tk+/tk- mouse lymphoma cell forward mutation assay: III. 72 coded chemicals.

Seventy-two chemicals were tested for their mutagenic potential in the L5178Y tk+/- mouse lymphoma cell forward mutation assay, using procedures based upon those described by Clive and Spector (Mutat Res 44:269-278, 1975) and Clive et al. (Mutat Res 59:61-108, 1979). Cultures were exposed to the chemicals for 4 hr, then cultured for 2 days before plating in soft agar with or without trifluorothymidine (TFT), 3 micrograms/ml. The chemicals were tested at least twice. Significant responses were obtained with allyl isothiocyanate, p-benzoquinone dioxime, benzyl acetate, 2-biphenylamine HCl, bis(2-chloro-1-methylethyl)ether, cadmium chloride, chlordane, chlorobenzene, chlorobenzilate, 2-chloroethanol, chlorothalonil, cytarabine.HCl, p,p'-DDE, diazinon, 2,6-dichloro-p-phenylenediamine, N,N-diethylthiourea, diglycidylresorcinol ether, 2,4-dimethoxy aniline.HCl, disperse yellow 3, endosulfan, 1,2-epoxyhexadecane, ethyl acrylate, ethyl benzene, ethylene thiourea, F D and C yellow Number 6, furan, heptachlor, isophorone, mercuric chloride, 4,4'-methylenedianiline.2 HCl, methyl viologen, nickel sulfate.6H2O, 4,4'-oxydianiline, pentachloroethane, piperonyl butoxide, propyl gallate, quinoline, rotenone, 2,4,5,6-tetrachloro-4-nitro-anisole, 1,1,1,2-tetrachloroethane, trichlorfon, 2,4,6-trichlorophenol, 2,4,5-trimethoxybenzaldehyde, 1,1,3-trimethyl-2-thiourea, 1-vinyl-3-cyclopetene dioxide, vinyl toluene, and ziram. Apart from 2-biphenylamine.HCl, 2-chloroethanol, disperse yellow 3, ethylene thiourea, FD and C yellow number 6, phenol, and 1,1,2-tetrachloroethane, rat liver S9 mix was not a requirement for these compounds. Chemicals not identified as mutagens were acid red, 11-aminoudecanoic acid, boric acid, 5-chloro-o-toluidine, coumaphos, cyclohexanone, decabromodiphenyl oxide, di(2-ethylhexyl)adipate, ferric chloride, fluometuron, melamine, monuron, phenesterin, phthalimide, reserpine, sodium dodecyl sulfate, 4,4-sulfonyldianiline, tetrachloroethylene, and zearalenone. The assay was incapable of providing a clear indication of whether some chemicals were mutagens; these were benzyl alcohol, 1,4-dichlorobenzene, phenol, succinic acid-2,2-dimethyl hydrazide, and toluene.

Animals↗
PubMed1980

General method for calculation of hydrogen-ion concentration in multicomponent acid-base mixtures.

A generalized method for the rapid evaluation of complicated ionic equilibria in terms of the hydrogen-ion concentration was developed. The method was based on the derivation of a single general equation that could be used to evaluate any mixture. A tableau method also was developed which allowed calculation of the numerical solution to the general equation without computer analysis or graphical or intuitive approximations. Examples illustrating the utility of the method are presented. These examples include a mixture of barbital, citric acid, boric acid, monobasic sodium phosphate, and sodium hydroxide. Calculated hydrogen-ion concentrations showed good agreement with experimental values for simple and complex solutions. The major advantages of the method are its simplicity and the obtainment of numerical solutions without initial approximations in the calculations. However, activity corrections are not included in the calculations.

Acids↗
PubMed2002

Separation and quantitation of phycobiliproteins using phytic acid in capillary electrophoresis with laser-induced fluorescence detection.

The similar electrophoretic mobilities and sizes of several of the phycobiliproteins, which are derived from the photosynthetic apparatus of cyanobacteria and eukaryotic algae, render their separation and quantitation a challenging problem. However, we have developed a suitable capillary electrophoresis (CE) method that employs a phytic acid-boric acid buffer and laser-induced fluorescence (LIF) detection with a single 594 nm He-Ne laser. This method takes advantage of the remarkably high quantum yields of these naturally fluorescent proteins, which can be attributed to their linear tetrapyrrole chromophores covalently bound to cysteinyl residues. As such, limits of detection of 1.18 x 10(-14), 5.26 x 10(-15), and 2.38 x 10(-15) mol/l were obtained for R-phycoerythrin, C-phycocyanin, and allophycocyanin proteins, respectively, with a linear dynamic range of eight orders of magnitude in each case. Unlike previously published CE-LIF methods, this work describes the separation of all three major classes of phycobiliproteins in under 5 min. Very good recoveries, ranging from 93.2 to 105.5%, were obtained for a standard mixture of the phycobiliproteins, based on seven-point calibration curves for both peak height and peak area. It is believed that this development will prove useful for the determination of phycobiliprotein content in naturally occurring cyanobacteria populations, thus providing a useful tool for understanding biological and chemical oceanographic processes.

Electrophoresis, Capillary↗