Reduction of non-specific binding in immunoassays requiring long incubations.

Despite the studies so far about the non-specific binding of antibody molecule to the plastic of solid phase in enzyme-linked immunoassays, background binding in microwell Elisa continues to be a troublesome problem.Non-specific immunoglobulin from an undiluted serum sample can adhere to the surface of a 'blocked' plate to result in a maximal signal in an antigen capture assay for specific antibody to render analysis virtually impossible in undiluted serum when using labelled anti-species antibodies. Yet it is desirable in many circumstances that the maximum sensitivity achievable by the simple expedient of using a concentrated sample (undiluted serum) be exploited, for example in the analysis of antibodies to HIV in the interest of earlier diagnosis.

Assessment of vitamin D status in male osteoporosis.

Background: Clinical assessment of vitamin D status often relies on measuring total circulating 25-hydroxyvitamin D3 (25OHD3), but much of each vitamin D metabolite is bound to plasma vitamin D-binding protein (DBP), such that the percentage of free vitamin is very low. We hypothesized that measurement of free rather than total 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] and 25OHD3 may provide better assessment of vitamin D status. We therefore aimed to assess vitamin D status in men with idiopathic osteoporosis, in whom possible secondary causes of osteoporosis had been excluded, and to determine the extent of change in biologically active "free" vitamin D caused by variation in plasma DBP concentrations.

Promotion of iridium-catalyzed methanol carbonylation: mechanistic studies of the cativa process.

The iridium/iodide-catalyzed carbonylation of methanol to acetic acid is promoted by carbonyl complexes of W, Re, Ru, and Os and simple iodides of Zn, Cd, Hg, Ga, and In. Iodide salts (LiI and Bu(4)NI) are catalyst poisons. In situ IR spectroscopy shows that the catalyst resting state (at H(2)O levels > or = 5% w/w) is fac,cis-[Ir(CO)(2)I(3)Me](-), 2.