Effect of stereochemistry on the molecular aggregation of phenylalanine dipeptide-type surfactants. (17/36)

The aggregation behaviors of three stereoisomers of tetramethylammonium N-dodecanoyl phenylalanylphenylalaninate in dilute aqueous solution were investigated. From surface tension, fluorescence intensity using probes, and heat of dilution measurements, it was suggested that the critical aggregation concentration was the same between the enantiomers, but was obviously different between the diastereomers. It was also found that these surfactants formed large aggregates at lower concentrations. These large aggregates were then transformed to micelles at higher concentrations similarly to the potassium N-acyl phenylalaninate system. Furthermore, the fluorescence intensity of auramine increased strikingly in the N-dodecanoyl-L-phenylalanyl-L-phenylalanine (homo-chiral dipeptide-type surfactant) system. The fluorescence intensity of auramine in the aggregate of homo-chiral dipeptide-type surfactant was 20 times larger than that in the hetero-chiral dipeptide-type surfactant.  (+info)

Conventional and molecular techniques in the diagnosis of pulmonary tuberculosis: a comparative study. (18/36)

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Evaluation of a rapid fluorescent staining method for detection of mycobacteria in clinical specimens. (19/36)

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The CyScope(R) fluorescence microscope, a reliable tool for tuberculosis diagnosis in resource-limited settings. (20/36)

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Fading of auramine-stained mycobacterial smears and implications for external quality assurance. (21/36)

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Functional and genetic characterization of the tap efflux pump in Mycobacterium bovis BCG. (22/36)

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UV-fixed-thick-blotch preparation improves sensitivity of auramine staining. (23/36)

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Immunofluorescence detection of Cryptosporidium oocysts in fecal smears. (24/36)

An indirect fluorescent antibody (IFA) procedure was developed for the detection of Cryptosporidium sp. oocysts in human, nonhuman primate, and bovine fecal smears. The procedure, which takes about 90 min to perform, involves the use of a rabbit antiserum against Cryptosporidium oocysts isolated from dairy cattle. Cross-specificity testing of the IFA method revealed no reactivity with yeasts, various amoebae, Giardia lamblia, Chilomastix sp., or Blastocystis sp. and only very weak cross-reactivity with coccidian oocysts of other genera. IFA detection of oocysts in human and nonhuman primate fecal smears was far more sensitive than was dimethyl sulfoxide-carbolfuchsin staining. Moreover, IFA detection was comparable in sensitivity to auramine O staining with samples of high oocyst concentration and somewhat more sensitive than auramine O with samples containing relatively few oocysts. The IFA procedure may be useful in the clinical diagnosis of human and animal cryptosporidiosis and also in the detection of oocysts in environmental samples.  (+info)