Acquisition of word-processing skills by younger, middle-age, and older adults.

A total of 45 subjects in three age groups (younger, middle-age, older) were trained to word process on microcomputers using a commercial training program and an experimenter-designed test and evaluation protocol. Although all of the subjects mastered the essentials of word processing, the older group took significantly longer to complete the training and evaluation procedures and performed more poorly on a review examination that tested their knowledge of the word-processing commands and techniques. The results are discussed in relation to requirements for trainer assistance, motivational factors, and the need to design training protocols that meet the needs of older adults. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

An essential role for retinoid receptors RARbeta and RXRgamma in long-term potentiation and depression

Hippocampal long-term potentiation (LTP) and long-term depression (LTD) are the most widely studied forms of synaptic plasticity thought to underlie spatial learning and memory. We report here that RARbeta deficiency in mice virtually eliminates hippocampal CA1 LTP and LTD. It also results in substantial performance deficits in spatial learning and memory tasks. Surprisingly, RXRgamma null mice exhibit a distinct phenotype in which LTD is lost whereas LTP is normal. Thus, while retinoid receptors contribute to both LTP and LTD, they do so in different ways. These findings not only genetically uncouple LTP and LTD but also reveal a novel and unexpected role for vitamin A in higher cognitive functions.     

Osmoprotective compounds in the Plumbaginaceae: a natural experiment in metabolic engineering of stress tolerance

In common with other zwitterionic quarternary ammonium compounds (QACs), glycine betaine acts as an osmoprotectant in plants, bacteria, and animals, with its accumulation in the cytoplasm reducing adverse effects of salinity and drought. For this reason, the glycine betaine biosynthesis pathway has become a target for genetic engineering of stress tolerance in crop plants. Besides glycine betaine, several other QAC osmoprotectants have been reported to accumulate among flowering plants, although little is known about their distribution, evolution, or adaptive value. We show here that various taxa of the highly stress-tolerant family Plumbaginaceae have evolved four QACs, which supplement or replace glycine betaine-namely, choline O-sulfate and the betaines of beta-alanine, proline, and hydroxyproline. Evidence from bacterial bioassays demonstrates that these QACs function no better than glycine betaine as osmoprotectants. However, the distribution of QACs among diverse members of the Plumbaginaceae adapted to different types of habitat indicates that different QACs could have selective advantages in particular stress environments. Specifically, choline O-sulfate can function in sulfate detoxification as well as in osmoprotection, beta-alanine betaine may be superior to glycine betaine in hypoxic saline conditions, and proline-derived betaines may be beneficial in chronically dry environments. We conclude that the evolution of osmoprotectant diversity within the Plumbaginaceae suggests additional possibilities to explore in the metabolic engineering of stress tolerance in crops.     

Shadowbowl 2003 [simulated mass-casualty exercise]

On 25-26 January 2003, a simulated mass-casualty exercise called ShadowBowl was conducted. A mass-casualty incident is an event in which local response capabilities are overwhelmed, and outside resources must be integrated as rapidly as possible to mitigate the situation. This article provides an account of the event, observations, and suggestions for improvements from the CRASAR perspective. ShadowBowl consisted of two tests, the first of which was a simulated earthquake response on 25 January 2003 and the remainder of which was an exercise conducted in parallel with Super Bowl XXXVII, with personnel and equipment on site at Qualcomm Stadium in San Diego, California, and across the country, in case a terrorist attack occurred. Capabilities that were demonstrated and tested include environmental monitoring (using sensors to detect radiation, water quality, and fire) and chemical hazard mitigation. This exercise was significant because it exposed a number of issues in a realistic emergency scenario, and the findings from the exercise can help to improve readiness for the next real disaster. Important lessons learned from ShadowBowl include what failed unexpectedly, the difficulty involved in performing what would otherwise be considered mundane tasks, and the ideal configuration of a local command center for specialists trying to use data coming from robots in the field. These lessons encompass critical components of reachback: communications, human factors, and adherence to standards. This article discusses the impact of unexpected failures on communications and other equipment, errant expectations, and information standards (synchronization and data formats).     

Trypanothione overproduction and resistance to antimonials and arsenicals in Leishmania

Leishmania resistant to arsenicals and antimonials extrude arsenite. Previous results of arsenite uptake into plasma membrane-enriched vesicles suggested that the transported species is a thiol adduct of arsenite. In this paper, we demonstrate that promastigotes of arsenite-resistant Leishmania tarentolae have increased levels of intracellular thiols. High-pressure liquid chromatography of the total thiols showed that a single peak of material was elevated almost 40-fold. The major species in this peak was identified by matrix-assisted laser desorption/ionization mass spectrometry as N1,N8-bis-(glutathionyl)spermidine (trypanothione). The trypanothione adduct of arsenite was effectively transported by the As-thiol pump. No difference in pump activity was observed in wild type and mutants. A model for drug resistance is proposed in which Sb(V)/As(V)-containing compounds, including the antileishmanial drug Pentostam, are reduced intracellularly to Sb(III)/As(III), conjugated to trypanothione, and extruded by the As-thiol pump. The rate-limiting step in resistance is proposed to be formation of the metalloid-thiol pump substrates, so that increased synthesis of trypanothione produces resistance. Increased synthesis of the substrate rather than an increase in the number of pump molecules is a novel mechanism for drug resistance.