Isolation of canine prolactin by polyacrylamide gel electrophoresis

The electrophoretic mobility of prolactin obtained from canine pituitary extract was studied with the aid of polyacrylamide disc electrophoresis. Using a preparative gel electrophoretic system the immunoreactive material was purified on a quantitative scale which was then used to develop a homologous radioimmunoassay for canine prolactin. The radioimmunoassay system was able to detect prolactin in the plasma of dogs after the administration of agents which would be expected to affect prolactin secretion.     

Erythrocyte spectrin peak II phosphorylation in Duchenne muscular dystrophy

Duchenne muscular dystrophy (DMD) is a rapidly progressive crippling disease of young boys that is inherited as an X-linked recessive trait. Previous studies have demonstrated the usefulness of erythrocyte studies in exploring membrane abnormalities in inheritied muscular dystrophy. Erythrocyte spectrin peak II protein (m.w. equivalent to 220,000) was more highly phosphorylated under initial rate conditions in DMD than in controls. The extent of peak II phosphorylation was greater in DMD erythrocytes and a Na+ stimulated peak II phosphorylation effect (Avruch and Fairbanks 1974) was not found to account for the differences between DMD and controls. The phosphorylated state of spectrin proteins in the membrane was evaluated and no differences in DMD could be measured. The maximal transfer of phosphate from differences in DMD could be measured. The maximal transfer of phosphate from [gamma-32P]ATP to spectrin peak II accounts for approximately 5-10% of the total phosphate content of spectrin.     

Acquired retinal folds in the cat

Retinal folds were found in 5 cats. The apparent cause of the folding was varied: in 1 cat the folds appeared after a localized retinal detachment; in 2 cats the condition accompanied other intraocular abnormalities associated with feline infectious peritonitis; 1 cat had active keratitis, and the retinal changes were thought to have been injury related; and 1 cat, bilaterally affected, had chronic glomerulonephritis.     

Cobalt-concanavalin A. An index of inactive and active conformational states

Studies on the circular dichroic spectrum of cobalt-substituted concanavalin A have been continued in particular with respect to calcium- and saccharide-induced spectral pertubations reported previously (Kalb, A.J. and Pecht, I. (1973) Biochim. Biophys. Acta 303, 264-268; Richardson, C.E. and Behnke, W.D. (1976) J. Mol. Biol. 102, 441-451). We find that the addition of calcium or cadmium to (CO2+)-concanavalin A induces slow time-dependent alterations in the extrinsic cotton effects. Moreover, one equivalent of calcium is sufficient to cause maximal changes in the cobalt spectrum provided sufficient time is allowed for the effect to be observed. The addition of mono, di-and trisaccharides, specific for concanavalin A, have no resolvable effect upon the cobalt spectrum of concanavalin A (Richardson, C.E. and Behnke, W.D. (1976) J. Mol. Biol. 102, 441-451). The data presented here suggest that these time-dependent processes are conformationally mediated and occur subsequent to S2 occupancy. Evidence is presented that a particular calcium-cobalt-concanavalin A conformer exists which is responsible for the generation of activity in a light-scattering assay system.