The extraction of the exopolymeric matrix is a prerequisite to properly assessing the composition of the biofilm. Several extraction methods have already been developed, however, no universal method has yet been adopted because the compromise between high yields of extraction and minimum cell lysis is difficult to establish. In fact, most of the extraction methods promote leakage of intracellul...

The presence of amino acid nitrogen in the non-protein nitrogen fraction of blood plasma was first established in 1912 by Van Slyke and Meyer (1). Chemical, microbiological, and chromatographic techniques have subsequently been employed to determine many of the individual amino acids which contribute to the total or-amino nitrogen as currently measured by the ninhydrin-CO2 method of Hamilton an...

The extraction of the exopolymeric matrix is a prerequisite to properly assessing the composition of the biofilm. Several extraction methods have already been developed, however, no universal method has yet been adopted because the compromise between high yields of extraction and minimum cell lysis is difficult to establish. In fact, most of the extraction methods promote leakage of intracellul...

We describe a mechanized method for determining total estrogens in plasma during the last trimester of pregnancy. This method involves rapid enzymic hydrolysis, automatic extraction (in a tube) with cyclohexane/ethyl acetate, purification of the extracted material by anion-exchange chromatography on a disposable "mini-column" of Dowex AG1 X 2 (acetate form), and continuous-flow fluorometric qua...

Preferential eosinophil chemotactic activity exhibiting a molecular weight comparable to that released from sensitized human lung fragments challenged with specific antigen and designated eosinophil chemotactic factor of anaphylaxis has been isolated from extracts of human lung fragments by sequential purification on Sephadex G-25, Dowex-1, Sephadex G-10, and paper chromatography. Two eosinophi...

2,3-Diphosphoglycerate was first isolated from red cells and identified by Greenwald (1). Greenwald’s procedure and modifications of it (2, 3) have been commonly used for isolation of this material, although the chemical synthesis has also been reported (4). Both the isolation procedure and the chemical synthesis are time consuming and do not lend themselves to the preparation of large quantiti...

The spectrophotometric procedure for determining the specific activity of the enzyme and the preparation of reagents employed in the assay have been described previously (3). DPiV-Commercial preparations of DPN (60 per cent) were used in routine assays. For critical experiments, commercial DPN was further purified by several adsorptions on Dowex 1 formate columns by the method of Kornberg and P...

We combined column and partition chromatography to isolate, purify, and quantify biological organic acids in urine and cerebrospinal fluid (CSF). Urine and CSF samples were introduced onto a preconditioned cation-exchange column (Dowex 50 W x 8 resin) to remove the biological interferences. The effluent with water was extracted with ethyl acetate two times (pH 1 and 3) and the organic acids wer...

In this screening method for urinary porphobilinogen (PBG), urine is added to Dowex 2 resin under alkaline conditions in a test tube and mixed. The supernate is removed and the adsorbed PBG is eluted with acid and reacted with Ehrlich's reagent. We compared results with those by the Watson-Schwartz screening method, using urine samples from normal people with and without added PBG. At a PBG con...

Tachyphylaxis to angiotensin and some analogues has been demonstrated on spirally cut arterial strips from cat, dog, sheep and rat, and on venous strips from rabbit and cat. Rabbit and guinea pig arteries do not appear to become tachyphylactic. A free C-terminal carboxyl group of angiotensin is necessary for binding with receptor sites and development of tachyphylaxis. Tachyphylaxis seems to re...