The non-specific inhibition of enzymes by environmental pollutants: a study of a model system towards the development of electrochemical biosensor arrays.

Previous research has shown that lactate dehydrogenase (LDH) was competitively inhibited by pentachlorophenol (PCP) and a modified assay produced a detection limit of 1 microM (270 microg l(-1)). This work used spectrophotometric rate-determination but in order to move towards biosensor development the selected detection method was electrochemical. The linkage of LDH to lactate oxidase (LOD) provided the electroactive species, hydrogen peroxide.

Amniotic fluid alpha-fetoprotein testing in native Japanese women.

Owing to differences in maternal serum alpha-fetoprotein, human chorionic gonadotrophin and oestriol levels between native Japanese and Caucasian women screened in this laboratory, a study was conducted to measure amniotic fluid alpha-fetoprotein (AFAFP) levels in native Japanese pregnancies. When the native Japanese AFAFP levels were compared with a United States (non-Black) population, the Japanese medians did not decrease as rapidly over the 14 to 22 weeks of gestation period investigated. At 14 weeks, the difference was negligible, graduating to a difference of 20 per cent by 22 weeks' gestation.

The rapid potentiometric detection of catalase positive microorganisms.

The rate of fluoride ion release from the enzymatic cleavage of fluoride ion from 4-fluorophenol by horseradish peroxidase, in the presence of hydrogen peroxide, was measured using a fluoride ion selective electrode. Monitoring the utilisation of hydrogen peroxide by catalase (intracellularly present in almost all aerobic microorganisms) in the presence of 4-fluorophenol demonstrated the inhibition of the enzyme. Horseradish peroxidase appeared to impart a partial protective mechanism of this inhibition.

Translocation of aged cyclodiene insecticide residues from soil into forage crops and pastures at various growth stages under field conditions.

Field trials were conducted to measure translocation of pesticides by summer and winter forage/pasture species from soil containing aged residues of heptachlor and, to a lesser extent, dieldrin. Substantial amounts of heptachlor epoxide, and lesser amounts of gamma-chlordane were translocated to plants from contaminated soil. Residue levels varied with crop species and stage of plant development.