Assessment of the risk of solar ultraviolet radiation to amphibians. I. Dose-dependent induction of hindlimb malformations in the northern leopard frog (Rana pipiens)

A number of environmental stressors have been hypothesized as responsible for recent increases in limb malformations in several species of North American amphibians. The purpose of this study was to generate dose-response data suitable for assessing the potential role of solar ultraviolet (UV) radiation in causing limb malformations in a species in which this phenomenon seemingly is particularly prevalent, the northern leopard frog (Rana pipiens). Frogs were exposed from early embryonic stages through complete metamorphosis to varying natural sunlight regimes, including unaltered (100%) sunlight, sunlight subjected to neutral density filtration to achieve relative intensities of 85%, 75%, 65%, 50%, and 25% of unaltered sunlight, and sunlight filtered with glass or acrylamide to attenuate, respectively, the UVB (290-320 nm) and UVB plus UVA (290-380 nm) portions of the spectrum. The experiments were conducted in a controlled setting, with continual monitoring of UVB, UVA, and visible light to support a robust exposure assessment. Full sunlight caused approximately 50% mortality of the frogs during early larval development; no significant treatment-related mortality occurred under any of the other exposure regimes, including 100% sunlight with glass or acrylamide filtration. There was a dose-dependent (p < 0.0001) induction of hindlimb malformations in the frogs, with the percentage of affected animals ranging from about 97% under unaltered sunlight to 0% in the 25% neutral density treatment. Malformations were comprised mostly of missing or truncated digits, and generally were bilateral as well as symmetrical. Filtration of sunlight with either glass or acrylamide both significantly reduced the incidence of malformed limbs. The estimated sunlight dose resulting in a 50% limb malformation rate (ED50) was 63.5%. The limb ED50 values based on measured sunlight intensities corresponded to average daily doses of 4.5 and 100 Wh x m(-2) for UVB and UVA, respectively. Exposure to sunlight also resulted in increased eye malformations in R. pipiens, however, the dose-response relationship for this endpoint was not monotonic. The results of this study, in conjunction with measured or predicted exposure data from natural settings, provide a basis for quantitative prediction of the risk of solar UV radiation to amphibians.     

Extending the solid-phase microextraction technique to high analyte concentrations: measurements and thermodynamic analysis

The solid-phase microextraction (SPME) technique has been used historically to quantify analytes present at the parts per million level. However, the nonintrusive nature of SPME lends itself to other applications involving analytes at higher concentration. In the current work, the possibility of using the SPME technique to measure concentrated gaseous samples was examined. Pentane concentrations between 0 and 100% saturation were studied, over a temperature range of 20-45 degrees C. The results showed that, up to a critical mole fraction in the solid phase, the concentrations of pentane in the polymeric extracting solid and vapor phases were related by a constant, equal to Henry's constant. The temperature dependence of Henry's constant was shown to follow the predicted trend with temperature, as determined from rigorous thermodynamic calculations. Above the pentane concentration in the polymeric phase, the response deviated from linearity. The nonideality was captured in an activity coefficient. An activity coefficient model developed to describe the nonideality was found to be a function of the swollen volume of the SPME polymer phase. The results indicate that the SPME technique can be applied to high analyte concentrations, although difficulties may be encountered when multiple analytes are absorbed.     

Sex differences in electrophysiological and behavioral responses to NaCl taste.

We tested the hypothesis that sex differences in preference for NaCl are attributable to estrogen-mediated alterations in gustatory processing. Electrophysiological responses of the chorda tympani nerve to NaCl were blunted by estrogen treatment in ovariectomized female rats, suggesting that females are less sensitive to concentrated NaCl solutions during high estrogen conditions. In contrast, after a taste aversion was conditioned to 150-mM NaCl, estrogen- and oil-treated ovariectomized rats generalized the aversion to a lower concentration of NaCl than did males, suggesting that females are more sensitive to the taste of dilute NaCl solutions regardless of estrogen. Thus, sex differences in NaCl preferences may be attributable to differences in NaCl taste processing that involve both acute and developmental effects of estrogen. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Long-term patterns and predictors of successful stressor resolution in later life.

At 1 year, 4 years, and 10 years after baseline, late-middle-aged adults reported whether they had successfully resolved their most important stressor of the past year. Compared to individuals who never resolved focal stressors over the 10-year interval, those who always did consistently showed less negative stressor appraisal, less reliance on avoidance coping, and less use of exploratory relative to directed coping responses, independent of type and severity of focal stressor. Less use of exploratory relative to directed coping and having more social resources, fewer health problems, and fewer depressive symptoms at baseline predicted more stressor resolution over the next 10 years. These predictors are promising foci for prospective efforts to optimize ways in which aging adults manage late-life stressors. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A quasi-qualitative investigation of strategies used in qualitative categorization.

This study investigates how analysts approach the task of initially categorizing qualitative data, what analysis strategies increase or decrease the testimonial validity of the categories, whether the data should be presented as a whole or in meaningful units, the effects of analysts' familiarity with the material, and the cognitive strategies associated with testimonial validity judgments. 30 upper level undergraduates (aged 19–42 yrs) analyzed essay data for "themes" while engaged in a think-aloud task. The essay writers then ranked the sets of categories in terms of overall quality and rated them on dimensions relevant to testimonial validity while thinking aloud. Think-aloud protocols for the best and worst approaches are examined. Implications for the use of qualitative research methods are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The relationship of victimization experiences to psychological well-being among homeless women and low-income housed women.

Stressful experiences and their effects on the psychological well-being of 113 homeless women and 116 low-income housed women were investigated. Measures of victimization assessed multiple dimensions of this construct, including criminal victimization, sexual harassment, and sexual abuse. Measures of current daily environmental hassles and quality of family environment while growing up also were included. Additional measures assessed positive and negative interpersonal exchanges, sense of coherence, and overall psychological distress. Regression analyses indicated that victimization experiences were significant predictors of psychological well-being for both samples. Results also highlighted the importance of investigating both the positive and negative dimensions of interpersonal influences as well as internal resources, and suggested that these resources for coping with stress may be differentially perceived and utilized by these groups. These findings also suggest the need for specific preventive and remedial interventions to empower homeless and low-income housed women. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Creating false memories: Remembering words not presented in lists.

Two experiments (modeled after J. Deese's 1959 study) revealed remarkable levels of false recall and false recognition in a list learning paradigm. In Exp 1, Ss studied lists of 12 words (e.g., bed, rest, awake); each list was composed of associates of 1 nonpresented word (e.g., sleep). On immediate free recall tests, the nonpresented associates were recalled 40% of the time and were later recognized with high confidence. In Exp 2, a false recall rate of 55% was obtained with an expanded set of lists, and on a later recognition test, Ss produced false alarms to these items at a rate comparable to the hit rate. The act of recall enhanced later remembering of both studied and nonstudied material. The results reveal a powerful illusion of memory: People remember events that never happened. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The role of vision in maternal attachment: Giving 2-year-olds a photograph of their mother during separation.

After being separated from their mothers, 48 Ss (20–30 mo old) were given either an unrecognizable or a sharply focused photograph of their mother to carry with them in an unfamiliar playroom. A female escort either correctly identified the photograph for the Ss, mislabeled it as a picture of a stranger, or gave it no verbal label. Ss with a clear photograph played, explored, and remained in the playroom longer than those presented with a blurred image. They also held, looked at, and spontaneously named the picture more. The verbal labels exerted no effects on separation behaviors or on responses directed toward the photographs. Results indicate that visual perception alone can suffice to provide Ss as young as 20 mo with some of the functional properties of their mother. (71 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Influence of selected organic compounds on the response of a calcium ion-selective electrode

The influence of some naturally occurring organic compounds on the response of a calcium ion-selective electrode has been investigated. Phenol, resorcinol, phthalate, salicylate and humic acid cause significant interference when their concentrations are greater than 10 mg¹⁻¹.     

Factors that contribute to the botulinal safety of reduced-fat and fat-free process chesse products

The effects of fat, type of natural cheese, and adjunct process cheese ingredients were evaluated to determine factors that contribute to the botulinal safety of reduced-fat (RF) process cheese products stored at 30 degrees C. In the first set of experiments, pasteurized process cheese products (PPCPs) were formulated using full-fat (FF) Cheddar, 30% RF Cheddar, or skim milk (SM) cheese as cheese-base types and were standardized to 59% moisture, pH 5.75, 2.8 or 3.2% total salts, and 15 to 19% fat. Subsequent trials evaluated the effect of fat levels and adjunct ingredients in PPCPs made with SM, RF, and FF cheese (final fat levels, less than 1, 13, and 24%, respectively). When fat levels of PPCPs were comparable (15.1, 19.1, and 16.2 for product manufactured with SC, RE and FF cheese, respectively), botulinal toxin production was delayed for up to 2 days in PPCPs formulated with SM compared with RF or FF cheese; however, the effect was not statistically significant. When fat levels were reduced to less than 1% in SM PPCPs, toxin production was delayed 2 weeks in products made with SM compared with RF or FF cheese manufactured with 13 or 24% fat, respectively. The antibotulinal effect of adjunct ingredients varied among the products manufactured with different fat levels. Sodium lactate significantly delayed toxin production (P < 0.05) for all fat levels tested, whereas beta-glucan fat replacer did not delay toxin production. An enzyme-modified cheese used as a flavor enhancer significantly delayed toxin production (P < 0.05) in SM (less than 1% fat) products but had little to no inhibitory effect in RF (13% fat) and FF (24% fat) cheese products. Similarly, monolaurin increased the time to detectable toxin in SM products but was ineffective in RF or FF cheese products. These results verify that RF PPCPs exhibit greater safety than FF products and that safety may be enhanced by using certain adjunct ingredients as antimicrobials.