The electrochemical activity determination of trypsin-like enzymes I - trypsin

Since 1970, a number of chromogenic substrates have been synthesized for the assay of the activities of enzymes intervening along the blood clotting process. The related studies have in all cases been restricted to homogeneous media. The aim of this work is to establish the conditions for the determination of enzymatic activities in the presence of solid dispersions. The principle of this analytical technique is based on the electrochemical detection of electroactive species, which can be directly related to the extent of an enzyme-catalyzed hydrolysis. For that purpose, a new substrate, benzoyl D,L arginyl p-aminodiphenylamide hydrochloride ( D,L BAPADA) has been synthesized and the method has been tested with trypsin as the enzyme. The substrate proved to be specific toward this enzyme. The amine released during the hydrolysis, the p-aminodiphenylamine (pADA), is electroactive in the anodic potential range, where neither the reduction of oxygen, nor the background discharge interfere. The amount of amine is periodically detected by its oxidation peak produced with an adequate potentiodynamic signal. The effects of several parameters which may affect the response signal have been checked by comparison with the calibration curve of the amine traced in the conditions met for the assay. Although the oxidation peak of the amine is qualitatively affected, the amperometric procedure nevertheless allows to use the calibration curve in order to convert the currents in terms of concentrations.By the use of a pretreated platinum electrode, first-order kinetics were obtained for the trypsin-substrate system. The magnitude of the kinetic constants fairly well compares with the spectrophotometric experiments carried out with substrates of the same kind.     

Do parents who smoke underutilize health care services for their children? A cross sectional study within the longitudinal PIAMA study

Background  

A higher prevalence of respiratory symptoms and an associated increase in health care utilization among children with parents who smoke is to be expected. From previous studies however, it appears that parents who smoke may underutilize health services for their children, especially with respect to respiratory care. This study explores the validity and generalizability of the previous assumption.     

Electrochemical activity determination of trypsin-like enzymes. IV. Coupled electrochemical and spectrophotometric assay of thrombin using the same H-D-Phe-Pip-Arg-4 MeO β naphtylamide, 2HCl (S-2421) substrate

The electrochemical activity determination of thrombin has been extended by the use of the carbon paste electrode coupled with the end-point titration procedure. The reliability of this technique is fairly well supported by the availability of the substrate S-2421 : H-D-Phe-Pip-Arg- 4 MeO β naphtylamide, 2HCl: the release of free amine can be monitored either spectrophotometrically or electrochemically. Results show that the kinetic constants of S-2421 obtained using each procedure compare with good agreement. A comparison of the data with those of other chromogenic and electrogenic substrates is given.     

Breast milk fatty acids and allergic disease in preschool children: the Prevention and Incidence of Asthma and Mite Allergy birth cohort study

BACKGROUND: Better understanding of the association between early life lipid intakes and the development of allergic diseases is needed. OBJECTIVE: We prospectively studied breast milk content of n-6, n-3, and trans fatty acids in relation to allergic symptoms at the ages of 1 and 4 years. METHODS: Fatty acid content was determined in breast milk samples of 265 (158 allergic and 107 nonallergic) mothers of children participating in the Prevention and Incidence of Asthma and Mite Allergy study. Outcome variables studied were parental reported eczema at age 1 year, eczema at age 4 years, asthma at age 4 years, and, in a subgroup of 133 children, sensitization at age 4 years. RESULTS: In children of mothers with allergy, breast milk n-3 long chain polyunsaturated fatty acids and the ratio between n-3 and n-6 long chain polyunsaturated fatty acids were inversely associated with asthma and with persistent symptoms (eczema at age 1 year and eczema at age 4 years and/or asthma at age 4 years), but no associations between breast milk fatty acids and sensitization were observed. In children of mothers with allergy, also trans fatty acids tended to be inversely associated with allergic symptoms. In children of mothers without allergy, no associations between breast milk fatty acids and allergic symptoms were observed, but alpha-linolenic acid (18:3n-3) was positively associated with sensitization. CONCLUSION: In susceptible infants, the risk to develop allergic symptoms, but not the risk of sensitization, was modified by intake of n-3 long chain polyunsaturated fatty acids through breast milk.