We study by molecular dynamics the interplay between arrest and crystallization in hard spheres. For state points in the plane of volume fraction (0.54 <or= varphi <or= 0.63) and polydispersity (0 <or= s <or= 0.085), we delineate states that spontaneously crystallize from those that do not. For noncrystallizing (or precrystallization) samples we find isodiffusivity lines consistent with an idea...

electron microscopy. Relaxation recurred 15 min after hormonal addition at 23°C. Similar experiments in cloned rat glomerular epithelial cells or "renin"producing cells did not demonstrate a contractile response. The contraction of MS cells was independent ofcyclic AMP (cAMP) and cyclic 3',5'-guanosine monophosphate (cGMP) production, even when cyclic nucleotides were measured as early as 30 s ...

The Cyclic Model attempts to resolve the homogeneity, isotropy, and flatness problems and generate a nearly scale-invariant spectrum of fluctuations during a period of slow contraction that precedes a bounce to an expanding phase. Here we describe at a conceptual level the recent developments that have greatly simplified our understanding of the contraction phase and the Cyclic Model overall. T...

Dibutyryl cyclic AMP and forskolin inhibited the contraction induced by norepinephrine (NE) more strongly than the high K(+)-induced contraction in isolated rat aorta. These inhibitors inhibited the 45Ca2+ influx stimulated by NE but not that by high K+, and they inhibited NE-induced inositol monophosphate accumulation. These results suggest that cAMP inhibits NE-induced contraction, at least p...

The activation of phosphorylase during muscle contraction and in the presence of epinephrine was studied in isolated frog sartorius and rat diaphragm, and in rat gastrocnemius in viuo. In all three tissues, epinephrine-induced conversion of phosphorylase b to a was accompanied by conversion of phosphorylase b kinase to the activated form (as evidenced by increased pH 6.8 to 8.2 activity ratios)...

We have used a combination of biochemical and pharmacological techniques to investigate the role of the cyclic nucleotides, 3', 5'-cyclic adenosine monophosphate (cyclic AMP) and 3',5'-cyclic guanosine monophosphate (cyclic GMP), in mediating the cardioregulatory effects of FMRFamide and other neuropeptides encoded on exon II of the FMRFamide gene of Lymnaea stagnalis. The 'isoleucine' peptides...