a detailed analysis of the electron-impact-induced fragmentation of 5,8dithiaspiro (3.1) octane and s,9-dithiaspiro 6.5) nonane is presented. the tetradeuteri6-analog of the cyclic dithioketals is prepared as an aid in analysing the fragmentation patterns. it was readily seen that the nature of the fragmentation pathway was governed by the size of the ring containing the two sulfur atoms and th...

Previous studies have shown that exogenous dibutyryl cyclic AMP inhibits the uptake of uridine, leucine, and 2-deoxyglucose by cultured mouse fibroblasts. 3':5'-cyclic GMP is shown here to counteract these inhibitory effects as well as the inhibition of precursor transport and leucine incorporation into proteins produced by prostaglandin E(1). We conclude, therefore, that cyclic GMP antagonizes...

We determine the structure of cyclic codes over Z4 for arbitrary even length giving the generator polynomial for these codes. We determine the number of cyclic codes for a given length. We describe the duals of the cyclic codes, describe the form of cyclic codes that are self-dual and give the number of these codes. We end by examining specific cases of cyclic codes, giving all cyclic self-dual...

A pheochromocytoma was maintained in rats from the New England Deaconess Hospital by giving the rats s.c. injections of isolated tumor cells. The animals were sac rificed 3 to 4 weeks after transplantation, the tumors were excised, and purified tumor cells were prepared. Cyclic nucleotide phosphodiesterase of the purified tumor cells was characterized and compared with that of the adrenal medul...

Cyclic GMP-dependent protein kinase, purified to homogeneity from bovine lung, was shown to activate hormone-sensitive lipase partially purified from chicken adipose tissue. The degree of activation was the same as that effected by cyclic AMP-dependent protein kinase although higher concentrations of the cyclic GMP-dependent enzyme were required (relative activities expressed in terms of histon...

we state several conditions under which comultiplication and weak comultiplication modulesare cyclic and study strong comultiplication modules and comultiplication rings. in particular,we will show that every faithful weak comultiplication module having a maximal submoduleover a reduced ring with a finite indecomposable decomposition is cyclic. also we show that if m is an strong comultiplicati...

background: there are many concerns regarding the marginal seal of composite restorations, especially when composite restorations are subjected to cyclic loading. the aim of this study was to evaluate the effect of cyclic loading on the microleakage of silorane based composite compared with low shrinkage methacrylate-based composites in class v cavities. materials and methods: in this in vitro ...

Phosphodiesterase activities for adenosine and guanosine 3’ : 5’-monophosphates (cyclic AMP and cyclic GMP) were demonstrated in particulate and soluble fractions of rat anterior pituitary gland. Both fractions contained higher activity for cyclic GMP hydrolysis than that for cyclic AMP hydrolysis when these activities were assayed at subsaturating substrate concentrations. Addition of protein ...