Effect of toxins 544 and 514 from Karwinskia humboldtiana (buckthorn) plant upon fetal development of the mouse

The teratogenic effect of toxins 544 and 514 from K. humboldtiana upon the mouse embryo was evaluated. One half of the LD50 dose for the mouse was administered at day 8 of gestation. At the end of pregnancy, reproduction and fetal data were recorded. Dams treated with toxin 544, but not with toxin 514, showed a higher incidence of reabsorptions, malformations, as well as lower fetal length compared to the control group.     

A new slant on orientation perception.

Traditional theories of orientation perception are unable to account for orientation judgments made by young children and for certain kinds of orientation judgments made by adults (e.g., aesthetic judgments of uprightness). The present article proposes that adults process orientation information at different levels and that these levels correspond to developmental stages in the coding of orientation in childhood. Many of the apparently anomalous judgments made by children and adults can be understood as processing at an early level where the only distinction made is between upright shapes and nonupright shapes. Results of 3 experiments conducted by the author and her associates with 48 college students, 5 2-yr-olds, and 12 3-yr-olds, are presented. They offer empirical support for this view. A new interpretation is offered for some of the orientation errors observed in clinical populations and in cross-cultural studies. (30 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Context effects in left-right shape discrimination.

The difficulty of discriminating between left–right orientations of a shape has usually been attributed to symmetrical coding in the brain or to the nature of perceptual learning. However, recent work on the context-dependent nature of the difficulty challenges such explanations and supports a more cognitive approach to the problem. The present work examined the basis for left–right difficulty in the standard two-choice task (stimuli aligned side by side) in children of 3 to 4 years. Experiment 1 found that children who learned the task with the easy, single-stimulus procedure could generalize to the difficult, two-choice task. Subsequent experiments found that the difficulty in learning the two-choice task could not be attributed to the attentional demands of the two stimuli, nor to the use of the second stimulus as a spatial referent for defining orientation. The data suggested that the standard two-choice task is difficult because it promotes the use of two competing orientation judgments. We conclude that the difficulty of left–right judgments lies in the cognitive demands of the task and is to be understood in the same terms as other problems in cognitive development. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Nitrogen compound distributions in hydrotreated shale oil products from commercial-scale refining

The distributions of nitrogen compounds in crude and hydrotreated shale oil products have been determined. About 11600 m³ (73000 bbl) of Paraho retorted shale oil were hydrotreated by The Standard Oil Company of Ohio at their Toledo refinery. A hydrotreated whole product, a jet fuel, a diesel fuel, and a residuum were produced and individually separated into compound-type fractions by adsorption chromatography. The nitrogen compound types in these fractions were characterized by i.r. spectroscopy, differential potentiometric titration, and high-resolution m.s. The distributions of nitrogen compound types and nitrogen base types in the hydrotreated products are compared with those in the Paraho retorted shale oil feedstock used in the hydroprocessing. The nitrogen compound types that were readily hydrodenitrogenated during commercial-scale refining are similar to nitrogen compound types removed during one-pass, bench-scale hydroprocessing.     

Cognitive level as a function of defensive isolation.

Evaluated the possibility that a failure to coordinate perspectives on the role-taking task (RTT) occurs when the TAT figures represent defensively isolated aspects of the self-structure. The Ss were given the RTT under 2 conditions: (1) Ss were assigned defensively isolated attributes, asked to tell a story built around TAT figures endowed with those attributes, and then required to take the perspectives of these figures in their role taking; (2) in the other, the assigned attributes were not defensively isolated. Ss showed more difficulty in coordinating perspectives under the defensive isolation condition than under the nonisolated condition. (17 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Horticultural postharvest loss in municipal fruit and vegetable markets in Samoa

Reducing horticultural postharvest loss is a priority in Samoa, due to declining agricultural productivity and wider dietary-based health concerns within the human population. Efforts to remediate loss is currently impeded by little information about the current levels of horticultural loss in Samoa or the factors contributing to this loss. In this study we quantified commercial postharvest loss of 23 horticultural crops at the Fugalei central municipal market on the Island of Upolu, Samoa, using direct weighing. Mean postharvest loss was further determined in all six municipal, community and private fruit and vegetable markets on the Samoan Islands of Upolu and Savai’i using vendor and farmer-trader surveys. Postharvest horticultural loss in the Fugalei municipal market was 6.2% (determined by weight) and 13.3% (based on vendor recall). There was no significant difference between mean postharvest loss in fruits compared to vegetables. The highest level of daily postharvest loss (5% to 22%) was observed for soursop, papaya, Tahitian lime, mustard cabbage and choko. Negligible loss (<1%) was observed in limes, vi (Spondias dulcis), eggplant, long bean, soa’a (plantains), lemon, cherry tomato, cucumber, pumpkin and ginger. The level of postharvest loss varied across the municipal, village and road-side markets surveyed, with higher losses in non-urban markets. There was no difference in the level of postharvest loss between any of the three urban markets in the Apia region. With most horticultural production located less than 20 km from the municipal market and little evidence of in-transit damage, transport logistics were unlikely to be an important contributor to loss. We believe low or sporadic consumer purchasing behaviour resulting in protracted market storage at high tropical ambient temperatures was the central contributor to observed losses. The potential importance of low consumer purchasing activity and the proportion of commercial vendor to transient farmer-trader in each of the markets is discussed in terms of being possible contributing factors to the resulting levels of postharvest loss and market variability.     

Negative Interactions in Irreversible Self-assembly

This paper explores the use of negative (i.e., repulsive) interactions in the abstract Tile Assembly Model defined by Winfree. Winfree in his Ph.D. thesis postulated negative interactions to be physically plausible, and Reif, Sahu, and Yin studied them in the context of reversible attachment operations. We investigate the power of negative interactions with irreversible attachments, and we achieve two main results. Our first result is an impossibility theorem: after t steps of assembly, Ω(t) tiles will be forever bound to an assembly, unable to detach. Thus negative glue strengths do not afford unlimited power to reuse tiles. Our second result is a positive one: we construct a set of tiles that can simulate an s-space-bounded, t-time-bounded Turing machine, while ensuring that no intermediate assembly grows larger than O(s), rather than O(s?t) as required by the standard Turing machine simulation with tiles. In addition to the space-bounded Turing machine simulation, we show another example application of negative glues: reducing the number of tile types required to assemble “thin” (n×o(logn/loglogn)) rectangles.     

Zinc-binding groups modulate selective inhibition of MMPs

The need for selective matrix metalloproteinase (MMP) inhibition is of interest because of the range of pathologies mediated by different MMP isoforms. The development of more selective MMP inhibitors (MMPi) may help to overcome some of the undesired side effects that have hindered the clinical success of these compounds. In an effort to devise new approaches to selective inhibitors, herein we describe several novel MMPi and show that their selectivity is dependent on the nature of the zinc-binding group (ZBG). This is in contrast to most current MMPi, which obtain isoform selectivity solely from the peptidomimetic backbone portion of the compound. In the present study, six different hydroxypyrone and hydroxypyridinone ZBGs were appended to a common biphenyl backbone and the inhibition efficiency of each inhibitor was determined in vitro (IC(50) values) against MMP-1, -2, -3, -7, -8, -9, -12, and -13. The results show that the selectivity profile of each inhibitor is different as a result of the various ZBGs. Computational modeling studies were used to explain some trends in the observed selectivity profiles. To assess the importance of the ZBG in a biological model, two of the semiselective, potent MMPi (and one control) were evaluated using an isolated perfused rat heart system. Hearts were subjected to ischemia reperfusion injury, and recovery of contractile function was examined. In this model, only one of the two MMPi showed significant and sustained heart recovery, demonstrating that the choice of ZBG can have a significant effect in a relevant pathophysiological endpoint.