Ascorbic acid, isoascorbic acid and dehydroascorbic acid quench the tryptophyl fluorescence of alkaline phosphatase. The quenching is protein aspecific, although its extent reflects the different inhibitory efficiency of the compounds. The kinetic inactivation and emission deactivation of alkaline phosphatase isoenzymes present also striking similarities. The fluorescence modifications, moreover, show a particular pattern, indicative of a transition phenomenon. The quenching effects displayed by the ascorbic system on alkaline phosphatase can then supply an interesting insight into other aspects of the inhibitor-enzyme interaction.

Alkaline Phosphatase↗

PubMedDate not supplied

A kinetic approach to the evaluation of alkaline phosphatase inactivation by urea.

A kinetic approach is described which enables the measurement of the enzyme inactivation rate constant during the reaction course. A mathematical analysis is presented and it is shown that a time-dependent step may be postulated to exist. Reaction kinetics follow an exponential rule with time as the independent variable and enzymatic activity as the dependent variable. A simple procedure of graphical analysis is reported and the influence on the inactivation rate constant of various conditions (temperature and inhibitor concentration) is evaluated. The method is illustrated by an experimental model: the inactivation of bovine kidney alkaline phosphatase by urea.

Alkaline Phosphatase↗

PubMedDate not supplied

Interaction between alkaline phosphatase and ascorbic acid by fluorescence and absorption studies.

Very low amounts of ascorbic acid modify alkaline phosphatase fluorescence, absorption and enzymatic activity. A strong quenching of enzyme, tryptophan and tyrosine emission together with evident alterations of the protein absorption characteristics are observed. The catalytic activity inhibition probably reflects a perturbation of the active site environment due to the interaction of ascorbic acid with enzyme aminoacyl residues.

Alkaline Phosphatase↗

PubMedDate not supplied

[Bioelectric profiles and nutritional status in pregnancy: protocol of a multicentric project to measure bioimpedance in pregnancy].

This paper re-examines the criteria underlying weight increases suggested during pregnancy. The distinction is introduced between increase in the lean and fat masses in the evaluation of the total weight increase, in order to assess the real mother's needs and work out a correct diet. Since one of the main adjustment mechanisms by the increase of the circulating mass and, more in general, the increase of water in the extracellular compartment, authors propose to use impedance measurements to longitudinally monitor the changes in the mother's lean mass during pregnancy and at the moment of delivery. The operational protocol of a multicentric project is presented, which aims at thoroughly analyzing the characterization of the mother's lean mass and its possible changes during pregnancy by means of bioimpedance measurements. A sample of 800 pregnant women will undergo bioimpedance measurements, 400 of which longitudinally during the whole pregnancy and 400 immediately before and after delivery. This study will also propose food frequency questionnaires in order to better define the nutritional status of pregnant women; moreover, sideremia, transferrin and ferritin values will be collected to assess any iron deficiencies in the studied population.

Adult↗

PubMedDate not supplied

Water supplementation enhances the effect of high-fiber diet on stool frequency and laxative consumption in adult patients with functional constipation.

BACKGROUND/AIMS: The purpose of this study was to determine the effects of a high-fiber diet and fluid supplementation in patients with functional chronic constipation. METHODOLOGY: One hundred and seventeen patients with chronic functional constipation (aged 18-50 years) were randomly divided into two treatment groups. For two months both groups consumed a standard diet providing approximately 25 g fiber per day. Group 1 (58 patients) was allowed ad libitum fluid intake, while Group 2 was instructed to drink 2 liters of mineral water per day. Compliance was monitored throughout the study and results were assessed in terms of bowel-movement frequency and laxative use. RESULTS: Fiber intake was similar in the two groups, while total daily fluid intake in Group 2 (mean 2.1 liters) was significantly greater than that of Group 1 (1.1 liters)(p < 0.001). In both groups, there were statistically significant increases in stool frequency and decreases in laxative use during the two-month trial, but both changes were greater in Group 2 (stool frequency: p < 0.001 vs. Group 1; laxative use: p < 0.001 vs Group 1). CONCLUSIONS: A daily fiber intake of 25 g can increase stool frequency in patients with chronic functional constipation, and this effect can be significantly enhanced by increasing fluid intake to 1.5-2.0 liters/day.

Adolescent↗