Regulation of Peripheral Catecholamine Responses to Acute Stress in Young Adult and Aged F-344 Rats

Young adult (3-month-old) and aged (24-month-old) Fischer-344 male rats received i.v. infusions of 3H-labeled norepinephrine (NE) and epinephrine (EPI) to examine the effects of aging on the neuronal uptake of NE and sympathoadrenal release of NE and EPI. Spillovers of NE and EPI into plasma and their clearance from the circulation were estimated from plasma concentrations of endogenous and 3H-labeled NE and EPI. The efficiency of neuronal uptake was assessed from changes in plasma clearance of NE and concentrations of its intraneuronal metabolite, dihydroxyphenylglycol (DHPG), during immobilization stress or neuronal uptake blockade with desipramine. Stress-induced increases in plasma NE and higher plasma NE concentrations in aged compared to young adult rats were due to both decreases in NE clearance and increases in NE spillover. EPI spillover and clearance were reduced in aged compared to young adult rats, so that plasma EPI levels did not differ between groups. Young adult and aged rats had similar desipramine-induced decreases in NE clearance, whereas desipramine-sensitive decreases and stress-induced increases in plasma DHPG were larger in aged rats. This indicates that neuronal uptake is intact and that increased NE spillover at rest and during stress in aged rats reflects increased NE release from sympathetic nerves. The results show that aging is associated with divergent decreases in EPI release from the adrenal medulla and increases in NE release from sympathetic nerves. Increased plasma concentrations of NE in aged compared to young adult rats also result from decreased circulatory clearance of NE, but this does not reflect any age-related impairment of NE reuptake.     

THE TROUBLE WITH LANGUAGE:

Abstract— Experiential avoidance is the attempt to escape or avoid certain private experiences, such as particular feelings, memories, behavioral predispositions, or thoughts. In this article, we discuss evidence that experiential avoidance is both pervasive and often harmful to human functioning. We argue that experiential avoidance can be explained by two verbal processes, and we provide basic behavioral evidence on both the bidirectionality of derived stimulus relations in verbal humans and the insensitivity to the effects of responding produced by verbal rules. If this analysis is correct, experiential avoidance is built into human language and thus can be undermined only with difficulty.     

A study of the concurrent validity of the Screening Test of Adolescent Language with recent immigrants.

The concurrent validity of the Screening Test of Adolescent Language was investigated by correlating the total scores for 152 first-year medical students with their performances on the Woodcock Language Proficiency Battery. The sample included many recent immigrants from southeastern Asia who were not yet highly proficient in English. The Pearson correlation of .78 between the two measures was high and statistically significantly different from zero.     

The phonetic effect in preschool children: The influence of overt rehearsal and verbal instructions

Preschoolers' serial matching of picture lists composed of either phonetically similar or unrelated items was compared under three types of conditions. The lower retention of phonetic lists had been used as an index of verbal mediation by Conrad (1971, 1972) who found that preschoolers did not show differential retention, and hence no verbal encoding, even when they were required to label overtly. This result was replicated and also obtained in a condition which emphasized the verbal aspects of the task. However, a significant phonetic effect and higher overall retention resulted from a condition which required overt, cumulative rehearsal. Alternative interpretations of the influence of rehearsal on the phonetic effect were offered.