A method to quantify sub-ppm levels of formaldehyde in acetone has been developed and it is reported here. In this method, the different reactivities and stabilities of sulfite with formaldehyde and acetone are used to separate the two carbonyl compounds. Sulfite reacts with formaldehyde to form hydroxymethanesulfonate (HMS), the non-volatile and stable nature of which allows its separation fro...

The diagnostic accuracy of two methods for measuring serum glutamic-oxaloacetic transaminase activity was examined in 50 cases of acute myocardial infarction proven by autopsy and in 12 nonfatal cases documented by rigid clinical criteria. All activities measured with the revised spectrophotometric method were elevated during the second day after infarction, and all patients had an elevated act...

1. Concentrations of ascorbic acid (ascorbic and dehydro-ascorbic; A + D; measured by the 2,4-dinitrophenylhydrazine method) of nearly three times those of plasma are present in gastric juice samples from patients with normal gastric histology. 2. A significant reduction in gastric juice ascorbic acid (A + D) was observed in patients with chronic gastritis. This reduction in concentration was i...

Among disruptions induced by oxidative stress, modifications of proteins, particularly irreversible carbonylation, are associated with the development of several diseases, including cardiovascular diseases, neurodegenerative diseases, and cancer. Carbonylation of proteins can occur directly or indirectly through the adduction of lipid oxidation products. In this study, three classical and easy-...

The interrelationships of L-ascorbic acid (AsA) and dehydro-L-ascorbic acid (DHA) have been investigated both in viva and in vitro by numerous workers, with especial emphasis upon the conversion of DHA to AsA by the animal body (l-8). The conversion of DHA to diketo-L-gulonic acid (DKA) in vitro has been shown by Herbert and coworkers (3), by Borsook (l), and by Penney and Zilva (6), and this c...

We have demonstrated that citrate synthase may be assayed by a simple, discontinuous, spectrophotometric procedure based on the measurement of oxaloacetate utilization with 2,4-dinitrophenylhydrazine. The assay is applicable both to the purified enzyme and to cell extracts, and has the advantage that it can be used in the presence of high concentrations of thiols and thioesters. We have used th...

The polarographic behaviour of formaldehyde (FA) was studied using cyclic and square wave polarography (SWP) methods. FA was derivatized with 2.4-dinitrophenylhydrazine (DNPH). The influence of several variables (including nature of the buffer, pH, concentration, scan rate, drop size, etc.) was examined in SWP method for FA. The best SWP responses were obtained in acetate buffer pH 5.0. The pea...

Modifications to the commonly used Schwimmer and Weston procedure for determining pyruvic acid in onions are proposed. These modifications involve changes in the concentrations and volumes of the reagents and the use of 515 rather than 420 nm as the wavelength for measurements. These changes improve both the linearity and the sensitivity of the assay and eliminate interference from coloured mat...

Ner protein of bacteriophage Mu, produced by recombinant DNA techniques in Escherichia coli, has been found to possess a molecule of pyruvic acid attached covalently through carbon-2 to the amino-terminal cysteine residue. The intact protein and the amino-terminal chymotryptic peptide were found by mass spectrometry to be 70 mass units heavier than expected. The modified peptide was unstable un...

In the course of experiments on the enzymatic transformation of steroids we were confronted with the problem of determining quantitatively small amounts of progesterone and pregnenolone (A6-pregnene-3@-ol-20-one). While progesterone can be easily estimated by its absorption maximum at 240 rnp, no spectrophotometric method has been known thus far for the determination of steroids with a ketone g...