No abstract

Eisenia foetida, a manure worm, showed characteristic symptoms of carbofuran poisoning (coiling and random muscle contractions). There appeared to be, however, a wide difference between this species and Lumbricus terrestris, the common dew worm, in susceptibility to this carbamate insecticide. Compared to the toxicity

A novel technique has been developed for measuring effective solute diffusivities in entrapment matrices used for cell immobilization. In this technique radiotracers were used to measure effective diffusivities and equilibrium partition coefficients of the solute between the liquid and solid matrix. Ca-alginate was used in this study, because it is one of the most commonly employed matrices for the immobilization of microbial, plant and mammalian cells. The experimental apparatus consisted of a single spherical Ca-alginate bead which was attached to a rotating rod and immersed in water containing C(14)-glucose. The rotational speed of the spherical bead was controlled and resulted in excellent mixing, and negligible external film mass transfer resistance, which allowed the measurement of true effective solute diffusivity within the solid matrix. The rates of C(14)-glucose diffusion within the Ca-alginate sphere were measured using a scintillation spectrometer. A mathematical model of unsteady-state diffusion in a sphere was used with appropriate boundary conditions, and the effective diffusivity of glucose was found from the best fit of the experimental data using a computer regression analysis method. Using 2% (w/v) Ca-alginate beads in this new radiotracer technique the effective diffusivity and partition coefficient of glucose were found to be 6.62 x 10(-10) m(2)/s and 0.98, respectively. The accuracy, advantages, and simplicity of this new method for diffusivity measurements are also compared to other existing methods.

The effects of tetraethyl lead, tetraethyl tin, triethyl lead, and triethyl tin on the metabolism of rat brain cortex slices have been studied. Tetraethyl lead and tetraethyl tin inhibit the active transport of amino acids into rat brain cortex slices at concentrations and under conditions that show no effect on the glucose metabolism of the slices. Tetraethyl lead and tetraethyl tin inhibit the oxidation of L-glutamate by rat brain slices. This effect can be accounted for on the basis of the inhibitory action of these two substances on the transport of the amino acid into the brain tissue.Tetraethyl lead and tetraethyl tin abolish, at low concentrations, potassium-stimulated brain slice respiration in presence of glucose, having little or no effect on unstimulated brain slice respiration. However, the respiration of rat brain cortex slices previously treated with phospholipase A is highly sensitive to tetraethyl lead.The inhibitory effects of the two tetraethyl compounds show differences from those of their triethyl derivatives indicating that the effects of the former substances are not due to admixture with, or conversion to, the latter substances.The brain slices of rats poisoned with either tetraethyl lead or tetraethyl tin are unable to effect the active transport of amino acids. The appearance of this biochemical abnormality coincides with the manifestation of neuropathological symptoms.The mode of action of tetraethyl lead and of tetraethyl tin on brain metabolism in vitro is discussed. It is suggested that they may act on phospholipid groups concerned with amino acid and cation transport at the cell membrane.

The detoxication of the geometrical isomers of Bomyl® (dimethyl-1,3-dicarbomethoxy-1-propen-2-yl phosphate) and Phosdrin® (mevinphos, dimethyl-1-carbomethoxy-1-propen-2-yl phosphate) by mouse liver has been studied. Most of the degrading activity for Phosdrin isomers was found in the supernatant fraction, whereas for Bomyl isomers it was equally distributed between the microsomal and the supernatant fractions. cis-Phosdrin is degraded in a system which requires reduced glutathione, the metabolites being cis-monomethyl-1-carbomethoxy-1-propen-2-yl phosphate (cis-desmethyl-Phosdrin)and S-methylglutathione. On the other hand, tras-Phosdrin and both Bomyl isomers were degraded to dimethyl phosphate. A method for the synthesis of cis-thiono-Bomyl is also reported. The possible general role of glutathione in the degradation of organophosphorus compounds is discussed.