Serum cobalamin concentrations are frequently low in the elderly but the cause is often not apparent. Because oral contraceptives have been associated with low cobalamin concentrations in young women, we compared hormone use with cobalamin status in elderly women to determine whether it could account for their unexplained low cobalamin concentrations. Thirty-eight of the 111 women had abnormal ...

Diagnosing cobalamin deficiency is often difficult. We investigated the diagnostic strategies that 224 general practitioners used to assess cobalamin status and the criteria on which they based their decisions to supplement patients. From all serum cobalamin analyses carried out at a single laboratory during 1993, individuals with serum cobalamin concentrations <300 pmol/L were identified, and ...

There is accumulating evidence for the existence of HNO in biological systems. Compared with NO (˙NO), much less is known about the chemical and biochemical reactivity of HNO. Kinetic and mechanistic studies have been carried out on the reaction between the vitamin B12-derived radical complex cob(II)alamin (Cbl(II)˙, Cbl(II)) with the widely used HNO donor Piloty's acid (PA). A stoichiometry of...

Approximately one-quarter of circulating cobalamin (vitamin B-12) binds to transcobalamin (holoTC) and is thereby available for the cells of the body. For this reason, holoTC is also referred to as active vitamin B-12. HoloTC was suggested as an optimal marker of early vitamin B-12 deficiency >20 y ago. This suggestion led to the development of suitable assays for measurement of the compound an...

Jasmonic acid (JA) and 12-oxophytodienoic acid (OPDA) are signal molecules involved in the stress and defense responses in plants. A full-length cDNA clon of OPR3 encoding 12oxophytodienoate reductase 3, key enzyme involved in the biosynthesis of JA from linolenic acid was obtained from a Solanum tuberosum cDNA library. Sequence analysis showed that OPR3 encoded a polypeptide of 400 amino acids...