Prenatal diagnosis of congenital mesoblastic nephroma in mid-second trimester by sonography and magnetic resonance imaging

Although congenital mesoblastic nephroma (CMN) is a rare benign congenital renal tumor, it is the most common solid renal tumor in the newborn period. The most common presentation of congenital mesoblastic nephroma is polyhydramnios, and only one case with prenatal fetal hydrops has been previously reported. Prenatal diagnosis of CMN has previously been made on the basis of the findings of sonography in the third trimester, and magnetic resonance imaging (MRI)–based diagnosis has been reported recently. Here we report a case of prenatally diagnosed classical type CMN diagnosed at 22 + 3 weeks of gestation based on the findings of sonography and magnetic resonance imaging. The characteristic imaging findings in this case were fetal hydrops and polyhydramnios. To our knowledge, this is the youngest reported gestational age for prenatal diagnosis of CMN and it is the second case of CMN associated with fetal hydrops detected prenatally. Copyright © 2003 John Wiley & Sons, Ltd.     

Habitat and age of the giant squid (<Emphasis Type="Italic">Architeuthis sanctipauli</Emphasis>) inferred from isotopic analyses

The age and habitat of the giant squid, Architeuthis sanctipauli Velain, 1877, were determined based on isotopic analyses of the statoliths of three female specimens captured off Tasmania, Australia, between January and March 1996. Assuming that the aragonite of the statoliths formed in equilibrium with seawater, ¹⁸O analyses indicated that the squid lived at temperatures of 10.5–12.9°C, corresponding to average depths of 125–250 m and maximum depths of 500 m. The capture records indicated that these squid may have occasionally ranged still deeper, to as much as 1000 m. All the statoliths were labeled with bomb ¹⁴C (¹⁴C=+22.9 to +44.6), consistent with the depths inferred from ¹⁸O. A thin section through one of the statoliths revealed 351 growth increments grouped into check-ring structures every 10–16 increments. A model for statolith growth and the pattern of temporal change in ¹⁴C in the water column was used to estimate the ages of the three specimens. These estimates were very sensitive to the choice of depth range over which ¹⁴C values were integrated. Assuming that the capture depths represented the maximum habitat depths of these individuals, the calculations suggested an age of 14 years or less. More refined age estimates require a better understanding of the variation of ¹⁴C and temperature with depth in the areas in which the squids live.Communicated by J.P. Grassle, New Brunswick     

Variation in resource availability changes the impact of invasive thistles on native bunchgrasses.

The threat posed by invasive nonnative plants to native plant populations is one of the largest challenges facing both conservation biology and restoration ecology. California has been highly impacted by invaders, although many relict stands of native plants are found on shallow, rocky soils with limited resources. The abiotic conditions of these sites may strongly influence the performance of an invasive plant and its effect on resident native species. In addition, the maturity of native plants in these sites may modulate an invader's impact; larger, well-established plants may be better able to resist invaders. In this study we examined how the impact of an invasive thistle (Centaurea solstitialis) on a native perennial bunchgrass (Nassella pulchra) changed in response to variation in soil depth, soil water availability, and bunchgrass maturity. We measured plant performance in terms of survival, growth, reproduction, and predawn water potential. We found that soil depth, water availability, and bunchgrass maturity acted in concert to influence the impact of the invasive thistle on the native bunchgrass. Both species performed better in deep soils, especially during dry years. The combination of shallow soil and low water availability reduced C. solstitialis performance and ameliorated its negative effect on N. pulchra growth and reproduction. Higher water availability resulted in a stronger negative effect of C. solstitialis on N. pulchra in both shallow and deep soils. However, as N. pulchra matured and increased in size, we saw a steady decline in C. solstitialis growth and reproductive output. Higher water availability increased the performance of C. solstitialis in shallow soils. C. solstitialis may thus have a stronger impact on N. pulchra and be more able to invade relict stands of N. pulchra in shallow soils during high-rainfall years. However, established stands of N. pulchra appear to be more resistant to invasion by C. solstitialis as N. pulchra plants grow older and larger.     

Driving performance comparing older versus younger drivers

Objectives: A cross-sectional study was conducted at the Touro University California campus to compare differences in reaction times and driving performance of younger adult drivers (18–40 years) and older adult drivers (60 years and older). Each test group consisted of 38 participants.

Methods: A Simple Visual Reaction Test (SVRT) tool was used to measure reaction times. The STISIM Drive M100 driving simulator was used to assess driving parameters. Driving performance parameters included mean lane position, standard deviation of mean lane position measured, mean speed, standard deviation of mean speed, car-following delay, car-following modulus, car-following coherence, off-road accidents, collisions, pedestrians hit, and traffic light tickets.

Results: Compared to younger participants, older drivers experienced significantly slower reaction times (510.0 ± 208.8 vs. 372.4 ± 96.1 ms, P =.0004), had more collisions (0.18 ± 0.39 vs. none, P =.0044), drove slower (44.6 ± 6.6 vs. 54.9 ± 11.7 mph, P <.0001), deviated less in speed (12.6 ± 4.3 vs. 16.8 ± 6.3, P =.0011), and were less able to maintain a constant distance behind a pace car (0.42 ± 0.23 vs. 0.59 ± 0.24; P =.0025).

Conclusions: Differences exist in driving patterns of older and younger drivers as measured by reaction times and driving simulator outcomes. These results are the first to compare these 2 specific adult age groups' driving performance as measured by a standardized driving simulator scenario. Identifying these differences is essential in addressing them and preventing future traffic injuries.     

The Application of Neutral Landscape Models in Conservation Biology

Neutral landscape models, derived from percolation theory in the field of landscape ecology, are grid-based maps in which complex habitat distributions are generated by random or fractal algorithms. This grid-based representation of landscape structure is compatible with the raster-based format of geographical information systems (GIS), which facilitates comparisons between theoretical and real landscapes. Neutral landscape models permit the identification of critical thresholds in connectivity, which can be used to predict when landscapes will become fragmented. The coupling of neutral landscape models with generalized population models, such as metapopulation theory, provides a null model for generating predictions about population dynamics in fragmented landscapes. Neutral landscape models can contribute to the following applications in conservation: (1) incorporation of complex spatial patterns in (meta)population models; (2) identification of species' perceptions of landscape structure; (3) determination of landscape connectivity; (4) evaluation of the consequences of habitat fragmentation for population subdivision; (5) identification of the domain of metapopulation dynamics; (6) prediction of the occurrence of extinction thresholds; ( 7) determination of the genetic consequences of habitat fragmentation; and (8) reserve design and ecosystem management. This generalized, spatially explicit framework bridges the gap between spatially implicit, patch-based models and spatially realistic GIS applications which are usually parameterized for a single species in a specific landscape. Development of a generalized, spatially explicit framework is essential in conservation biology because we will not be able to develop individual models for every species of management concern.     

The Case for Diminishing Marginal Existence Values

This study addresses the debate over sensitivity of existence values measured by contingent valuation to scope tests. We reconcile much of the debate within one theoretical model. If marginal WTP for existence goods is diminishing, then a study that tested for sensitivity to scope over a range for which marginal WTP is high would be more likely to detect sensitivity to scope than a study that focused on a range for which marginal WTP is much lower. An empirical model demonstrates this point for existence value of remote wilderness parks. These results have significant implications for future contingent valuation work.     

Polymodal foraging in adult female loggerheads (Caretta caretta)

To determine whether loggerhead turtles (Caretta caretta) nesting in southeastern USA exhibit polymorphic foraging strategies, we evaluated skin samples for stable isotopes of carbon (δ¹³C) and nitrogen (δ¹⁵N) from 310 loggerheads from four locations on the east coast of Florida and epibionts from 48 loggerheads. We found a dichotomy between a depleted δ¹³C cluster and an enriched δ¹³C cluster. Epibionts from oceanic/pelagic or neritic/benthic habitats were largely consistent with this dichotomy. The bimodal distribution of δ¹³C could reflect a bimodal foraging strategy or—because of the potential for confounding among four gradients of δ¹³C in marine environments—a polymodal foraging strategy. We integrate our results with results from other stable isotope studies, satellite telemetry, and flipper tags to evaluate potential foraging strategies. Understanding foraging strategies is essential for development of management plans for this endangered species that has suffered a 43% population decline over the last decade.     

Acetylcholinesterase activity in Corbicula fluminea Mull., as a biomarker of organophosphate pesticide pollution in Pinacanauan River, Philippines

Organophosphates are known to inhibit the enzyme acetylcholinesterase. In this study, the AChE activity from the total soft tissues of Corbicula fluminea Mull. was used as a biomarker of organophosphate pollution in Pinacanauan River. Clams were collected from two different sites and at different seasons of the year. A colorimetric assay on the total soft tissues of the clams showed a directly proportional relationship between enzyme activity and condition of the riverine system. In vitro experiments on the total soft tissue, adductor muscles, digestive glands, and gills were conducted to assess the degree of localization of AChE as well as the sensitivity and tolerance of the enzymes in these tissues to varying concentrations of malathion. The degree of enzyme localization from highest to lowest is as follows: adductor muscle > gills > digestive gland whereas sensitivity to OP from greatest to least is: gills > adductor muscles > digestive gland.