Vascular Smooth Muscle: Dual Effect of Calcium

The first part of the contractile response of rabbit aorta to epinephrine is depressed by elevation of calcium concentration; the second is potentiated. These observations suggest that the rate-limiting factor for the former is membrane excitability (depressed by increased calcium), while that for the latter is the role that calcium plays in coupling membrane excitation with the development of tension by the contractile protein (a function that is augmented by increased calcium).     

Oligoribonucleotides: improvement in chromatographic separation

The separation of mixed oligoribonucleotides obtained from enzymatic digestion of soluble RNA into fractions containing mixed oligonucleotides of identical chain length is improved by absence of terminal phosphate. Each fraction may be separated into individual components by ionexchange (Dowex) chromatography. Combination of these two chromatographic procedures yields maximum information on primary structure of the oligonucleotides.     

Demyelinating encephalomyelopathy associated with lead poisoning in nonhuman primates

Lead poisoning was diagnosed in four primates by the finding of toxic amounts of lead in tissues. Abnormalities in the brain and spinal cord were characterized by vascular lesions and demyelination. These findings suggest a new animal model for the study of demyelination and strengthen the supposition that lead may be a factor in some idiopathic demyelinating diseases.