Islet amyloid polypeptide decreases the effects of insulin-like growth factor-I on glucose transport and glycogen synthesis in skeletal muscle

Previous studies have shown that islet amyloid polypeptide (IAPP) is co-secreted with insulin from the beta-cell. IAPP reduces insulin-stimulated rates of glycogen synthesis in skeletal muscle but the mechanisms are unclear. Insulin-like growth factor I (IGF-I) is an important regulator of glucose metabolism in skeletal muscle and acts through its own receptor, which has many structural and functional similarities with the insulin receptor. Despite this, the effects of IGF-I on glucose utilization are not identical to those of insulin. The aim of the study was to determine the effects of IAPP on IGF-I-stimulated rates of glucose transport and metabolism (measured by 3-O-methyl[3H]glucose and [U-14C]glucose, respectively) in rat soleus muscle, and compare them with those simulated by insulin. IAPP (10 nM) decreased the sensitivity of 3-O-methylglucose transport, the flux of glucose to hexosemonophosphate and the sensitivity of glycogen synthesis to IGF-I. In contrast, IAPP had no effect on IGF-I-stimulated rates of lactate formation (i.e., glycolysis). IAPP decreased the sensitivity of 3-O-methylglucose transport and glycogen synthesis to insulin. It is concluded that IAPP blunts the stimulation of glucose uptake and deposition by IGF-I or insulin in skeletal muscle. These observations expand those made initially for IAPP and insulin and suggest that IAPP affects IGF-I- or insulin-stimulated glucose metabolism in muscle by a mechanism which is common for both hormones. These experiments may serve as a framework for future studies in order to clarify the mechanisms by which IAPP affects glucose metabolism in skeletal muscle.     

Conformity under varying conditions of personal commitment.

This study tested a central proposition, stemming from Rotter's Social Learning Theory, that conformity is related to low expectations of success in socially evaluative situations and is consequently accompanied by defensive processes. 2 variants of an Asch situation representing increasing degrees of personal commitment were compared to a control condition. Situational measures of confidence included betting and statements of expectancy. Additional personality indices included level of aspiration, need for approval, and internal vs. external control of reinforcement. The Ss were 110 introductory psychology students. Results depict the conformer as one who has a low expectation of success in evaluative situations. His lesser confidence leads to avoidant behavior to resolve the ensuing conflict. Defensive processes of the conformer tend to become more marked as personal commitment increases. (17 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The Ferroelectric Slab Waveguide: A Geometry for Microwave Components that Incorporate Ferroelectric Materials

A slab geometry, in which ferroelectric is inserted between two “cladding” layers with a microstrip electrode placed on top, is proposed as a way to integrate the properties of ferroelectric materials into microwave components. This structure distributes the propagating microwave fields between the ferroelectric and the cladding, so that the microwave dielectric constant is a weighted average of the dielectric constants of the two materials. It is shown that this geometry drastically reduces dissipation due to dielectric losses in the ferroelectric. In addition, by applying a dc bias to the microstrip line, the dielectric constant of the ferroelectric layer can be varied and with it the microwave properties of the structure.     

Self-acceptance and self-evaluative behavior: A critique of methodology.

Research concerned with self-acceptance has contributed very little to the understanding of the concept. The research evidence is inadequate because investigators have neglected several crucial psychometric and methodological principles. The absence of data concerning the generality of self-acceptance and the implications of the difference between a phenomenological approach to self-acceptance and a behavioristic approach makes interpretation of research results even more difficult. From Psyc Abstracts 36:02:2HE04C. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Multivariate analysis of putative measures of activity, exploration, emotionality, and spatial behavior in the hooded rat (Rattus norvegicus).

Hooded rats were tested in six situations representing the variables of activity, exploration, emotionality, and spatial preference, detection of change, and learning. The activity, exploration, and emotionality variables and spatial variables were analyzed in separate multivariate analyses, followed by an analysis of the entire set. The first of these resulted in four components: activity, exploration and emotionality, reactivity to handling, and autonomic reactivity (defecation). Four components, defined by following variables, emerged from the spatial analysis: (a) the tendency to circle, circling direction, and spatial learning; (b) heading error in spatial learning and reversal and open-field directional preference; (c) spatial reversal and direction of turn to escape restraint; and (d) detection of change in spatial arrangement and directional preference in the detection task. The final analysis investigated relations between the activity, exploration, and emotionality variables and the spatial variables, finding only two. The clear dimensionality of these behavioral repertoires emphasizes how important it is to recognize the distinctions among them. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Mechanism for the high voltage photovoltaic effect in ceramic ferroelectrics

The high-voltage photo-emf seen in poled ferroelectric ceramics is explained as the result of light-induced carriers screening an internal field within the bulk of individual grains. The internal field itself is explained as the result of the shielding by equilibrium carriers of the potential produced by the spontaneous polarization. Less-than-band-gap emf’s are produced across individual grains; these emf’s add in ceramics to produce the high-voltage photo-emf. A model yields the polarity and magnitude of the photo-emf, the dependence on temperature, remanent and spontaneous polarization, dielectric constant and grain size. The calculated and experimental results are in general agreement.     

Correction for attenuation and the equivalence of tests.

Block (1963) suggested that in estimating the equivalence of tests E should correct for unreliability to give a more appropriate estimate of the "conceptual equivalence" of the tests. In the present paper it is pointed out that: a distinction should be made between conceptual equivalence and functional equivalence; functional equivalence is of prior importance in research seeking relationships of other variables to the variable represented by the tests; in estimating functional equivalence it is not apropriate to correct for unreliability; and, in fact, correction for attenuation may often lead to over-generalization of results. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Lateralization of emotionality in right parietal cortex of the rat.

Lesions of right parietal cortex in the rat increase activity in the open field compared with left parietal lesions, especially after section of the corpus callosum. Left or right motor or medial frontal cortex lesions do not have a lateralized effect. This evidence of a localized asymmetry between the cerebral hemispheres strongly implies that right parietal cortex has a role in emotionality in this species. Our findings suggest a functional similarity to right parietal cortex in man. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of unilateral parietal lesions on spatial localization in the rat.

In the 1st of 2 experiments, rats with left or right parietal lesions and controls were tested in place and landmark navigation in the water maze. Right parietal lesions resulted in deficits in both tasks, but especially landmark navigation. Lateralized effects appeared mainly in latency to find the platform. Exp 2 investigated the role of the corpus callosum. Split-brain rats with unilateral parietal lesions were tested on the same 2 tasks. Place and landmark deficits were particularly severe, but lateralization was weaker. Callosum section had its own effect, impairing the learning of both tasks. There appear to be additive effects of unilateral cortical lesions and bisection of the hemispheres. The impairment from left lesions equaled the right-lesion deficit because of the interruption of compensatory information from the intact right hemisphere and the effect of callosum section itself. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Comment on Cooper's "The passing of psychology" (Vol. 23, no. 4, October 1982).

Comments on R. M. Cooper's original article, "The passing of psychology" (see record 1983-26906-001). According to Cooper, psychology has become fruitless, devoid of substance and honest accomplishment and the real productivity of science is to be seen in material accomplishments. According to the current author, a materialist view makes any step in the world of ideas pitifully small by comparison. Materialist "science" will seem awesome, while enlargement of understanding that does not have an immediate physical expression can only be trivial musing. This is an all too prevalent view of science. Psychology is not dead. The science and practice of psychology are blessed, as they have long been, with keen and competent minds. (PsycINFO Database Record (c) 2010 APA, all rights reserved)