Effects of differential spatial orientation on tactual pattern recognition

This study assessed the effects of variation in the relative spatial orientation of figures on tactual pattern recognition. Metric figures at two levels of complexity, 4 × 4 and 6 × 6, were used. Ss were required to determine which of two choice figures was identical to a previously presented target (identity indicator response) or, if neither of the two choice figures was identical to the target (non-identity indicator response). Two orientation conditions were employed: (1) all figures were oriented in the same direction and (2) choice figures were oriented in different directions relative to the target and to each other. In general, differential orientation degraded both the accuracy and speed of recognition. The negative effects of differential orientation were dependent upon figure complexity and the type of indicator response when perceptual performance was measured in terms of accuracy but not when a speed index was used. Patterns at the low level of complexity were recognized more rapidly than high complexity patterns when a non-identity indicator response was required; no differences between complexity levels were noted with the identity indicator response.

Insulin biosynthesis in the rat: demonstration of two proinsulins

Proinsulin, a single-chain precursor of insulin, has been detected in biosynthetic studies in vitro,(1-4) and in crystalline preparations of insulin from several species.(1, 5-7) It appears that proinsulin normally serves neither as a major storage nor secretory form of the hormone.(8) Its primary functions seems to be to facilitate the efficient formation of the disulfide bonds of insulin.(9)Although several species of fish have two insulins differing slightly in primary structure,(10-12) the rat is the only mammal where this is known to be the case.(13, 14) As the two rat insulins are nonallelic(14) and presumably coded by two distinct genes, a separate proinsulin would be expected to precede each insulin. We have demonstrated the biosynthesis of both insulins(15) and of a proinsulin corresponding to each in isolated islets of Langerhans, and have detected probable intermediates in the conversion of these proinsulins to insulin. Labeled peptide material corresponding to the free connecting segment of proinsulin (C-peptide) was detected in insulin-containing fractions isolated from incubated rat islets. It was noted that islets incubated in vitro secreted small amounts of newly synthesized proinsulin as well as the two insulins and essentially equivalent amounts of C-peptide. Increasing the glucose content of the medium selectively enhanced the incorporation of radioactivity into proinsulin and insulin and also seemed to increase the relative proportion of labeled proinsulin appearing in the medium.

The spontaneous reoxidation of reduced beef and rat proinsulins

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