Orrin B. Myers

Tree die‐off in response to global change‐type drought: mortality insights from a decade of plant water potential measurements

Global climate change is projected to produce warmer, longer, and more frequent droughts, referred to here as “global change-type droughts”, which have the potential to trigger widespread tree die-off. However, drought-induced tree mortality cannot be predicted with confidence, because long-term field observations of plant water stress prior to, and culminating in, mortality are rare, precluding the development and testing of mechanisms. Here, we document plant water stress in two widely distributed, co-occurring species, pinon pine (Pinus edulis) and juniper (Juniperus monosperma), over more than a decade, leading up to regional-scale die-off of pinon pine trees in response to global change-related drought. Pinon leaf water potentials remained substantially below their zero carbon assimilation point for at least 10 months prior to dying, in contrast to those of juniper, which rarely dropped below their zero-assimilation point. These data suggest that pinon mortality was driven by protracted water stress,...

Differential use of spatially heterogeneous soil moisture by two semiarid woody species: Pinus edulis and Juniperus monosperma

1 Soil moisture in semiarid woodlands varies both vertically with depth and horizontally between canopy patches beneath woody plants and the intercanopy patches that separate them, such that shallow soil layers in intercanopy locations are wettest, yet few studies have considered both dimensions of spatial variability in testing for acquisition of resources by plants. 2 Three hypotheses were tested relative to the use of shallow water in intercanopy locations by two coexisting semiarid-woodland tree species, Pinus edulis (a pinion) and Juniperus monosperma (a juniper): (i) both P. edulis and J. monosperma can use shallow water from intercanopy locations;. (ii) J. monosperma is able to obtain more shallow water from intercanopy locations than P. edulis, and (iii) the spatial arrangement of the trees influences the amount of water they obtain. Soil moisture and plant water potential (i.e. plant water stress) were measured before and after the addition of water to shallow depths (0-30 cm) of intercanopy locations for trees of both species in two spatial arrangements: isolated and paired with a contiguous tree of the other species. 3 Both species responded to the addition of shallow water in intercanopy locations, as measured by plant water potential. The response of J. monosperma was significantly greater than that of P. edulis, as measured by depletion of shallow soil moisture in intercanopy locations and by change in plant water potential per unit change in soil water potential (the difference was not detectable on the basis of plant water potential alone); in addition, the amount of depletion was correlated with basal area of J. monosperma but not of P. edulis. The responses were not influenced by spatial arrangement (isolated vs. paired with a contiguous tree of the other species). 4 The results of this study are consistent with differences in the relative abundances of the two species across locations, suggesting that species differences in ability to use shallow water in intercanopy locations is important in structuring semiarid woodlands. Further, the results suggest that current theoretical concepts for semiarid ecosystems, which ignore either vertical or horizontal variability in soil moisture, may be inadequate for predicting changes in the ratio of woody to herbaceous plant biomass, particularly for plant communities with co-dominant woody species that differ in ability to acquire spatially heterogeneous resources.

Age, Race, Diabetes, Blood Pressure, and Mortality among Hemodialysis Patients

Observational studies involving hemodialysis patients suggest a U-shaped relationship between BP and mortality, but the majority of these studies followed large, heterogeneous cohorts. To examine whether age, race, and diabetes status affect the association between systolic BP (SBP; predialysis) and mortality, we studied a cohort of 16,283 incident hemodialysis patients. We constructed a series of multivariate proportional hazards models, adding age and BP to the analyses as cubic polynomial splines to model potential nonlinear relationships with mortality. Overall, low SBP associated with increased mortality, and the association was more pronounced among older patients and those with diabetes. Higher SBP associated with increased mortality among younger patients, regardless of race or diabetes status. We observed a survival advantage for black patients primarily among older patients. Diabetes associated with increased mortality mainly among older patients with low BP. In conclusion, the design of randomized clinical trials to identify optimal BP targets for patients with ESRD should take age and diabetes status into consideration.

The Ecological and Physiological Costs of Lead Shot and Immunological Challenge to Developing Western Bluebirds

We investigated the interacting effects of a nonpathogenic immunological challenge and exposure to lead shot early in the development of nestling western bluebirds (Sialia mexicana). Nestlings were randomly assigned to each of six treatments of an incomplete block design with two antigen treatments, Newcastle disease virus (NDV) or sheep red blood cells (SRBC), and four lead shot treatments (no shot, one shot – 0.05 g, 2 shots – 0.1 g, or three shots – 0.15 g). Survival functions did not differ between the lead treatment groups, and there were no effects of lead treatments on weight, growth rates, fluctuating asymmetry (FA), or antibody response. NDV- and SRBC-treated birds survived better than control birds which may be due to an adjuvant-activation of the entire immune system. However, FA was greater in individuals in the NDV and SRBC treatment groups, suggesting a tradeoff between growth and immunocompetence. Cell-mediated response to phytohemagglutinin of the high-lead treatment groups was significantly less than other groups. Hematocrit increased with age and weight, and was not affected by lead or antigen. While in this study the shape of the growth curve, FA, cell-mediated immunity, and behavior were affected by the higher dose of lead shot, actual lead concentrations in blood are needed to verify this process. Antigenic stress was documented in nestling developmental stability and there were no measured effect of both the lead shot and immunological challenge in combination.

Heat shock response and autophagy--cooperation and control.

Protein quality control (proteostasis) depends on constant protein degradation and resynthesis, and is essential for proper homeostasis in systems from single cells to whole organisms. Cells possess several mechanisms and processes to maintain proteostasis. At one end of the spectrum, the heat shock proteins modulate protein folding and repair. At the other end, the proteasome and autophagy as well as other lysosome-dependent systems, function in the degradation of dysfunctional proteins. In this review, we examine how these systems interact to maintain proteostasis. Both the direct cellular data on heat shock control over autophagy and the time course of exercise-associated changes in humans support the model that heat shock response and autophagy are tightly linked. Studying the links between exercise stress and molecular control of proteostasis provides evidence that the heat shock response and autophagy coordinate and undergo sequential activation and downregulation, and that this is essential for proper proteostasis in eukaryotic systems.

A Population-Based Evaluation of Cervical Screening in the United States: 2008–2011

Background: Cervical screening consumes substantial resources, but little is known about utilization in the United States or compliance with guideline recommendations. Methods: To describe population screening coverage, utilization, and outcomes and examine time trends from 2008 to 2011, cervical cytology reports from women residing in New Mexico (981,063 tests from 511,381 women) were evaluated. Results: From 2008 to 2011 cervical screening utilization decreased at all ages, but especially in younger women, with a two-third reduction at ages 15 to 20 years. Ninety-four percent of women ages 25 to 29 years were screened within 48 months but coverage decreased at older ages to 69% at 45 to 49 years and 55% at 60 to 64 years. Intervals between screening tests were significantly longer in 2011 compared with 2008 [HR = 1.23; 95% confidence intervals (CI), 1.22–1.24], although the commonest rescreening interval was 13 months. In 2011, 91.9% of screening tests for women ages 21 to 65 years were negative, 6.6% showed minor abnormalities, and 1.0% high-grade abnormalities. High-grade abnormality rates were relatively constant over time, but minor abnormalities and atypical cells cannot rule out high-grade (ASC-H) were increasing. Conclusions: This population-based evaluation of cervical screening shows high coverage under the age of 40 years, but lower levels in older women. Screening under age 21 years is becoming less common and screening intervals are lengthening, reflecting updates in national screening guidelines. Impact: Assessment of cervical screening intervals and population outcomes is essential for accurately estimating the impact and effectiveness of changing recommendations and vaccination against human papilloma virus infections. Cancer Epidemiol Biomarkers Prev; 23(5); 765–73. ©2013 AACR.

IMMUNE AND GROWTH RESPONSE OF WESTERN BLUEBIRDS AND ASH-THROATED FLYCATCHERS TO SOIL CONTAMINANTS

During the past two decades, a critical need has developed to determine how exposure to contaminants in the environment affects individual and population processes. In this study, the immunocompetence of Western Bluebirds (Sialia mexicana) and Ash- throated Flycatchers (Myiarchus cinerascens) was studied on a landscape-soil contaminant gradient at Los Alamos National Laboratory (LANL) in New Mexico during 1997-1999. A variety of contaminants (heavy metals, chemicals, insecticides, polychlorinated biphenyls, and radioactive isotopes) range across different spatial scales and concentrations on LANL land. The two species have similar life-history traits, except that the Ash-throated Flycatcher has a faster rate of development and fledges 4-5 days earlier than the bluebird. The number of active nest boxes increased from 1997 to 1998 and 1999 for the Western Bluebird, but not for the Ash-throated Flycatcher. Survival of nestling flycatchers was lower in areas within 60 m of a potential contaminant release site, with a higher survivorship function associated with boxes farther away. The two species did not differ in their response to antigens, and there was no difference between locations for immunocompetence for either species. Flycatcher nestlings had a higher average cell-mediated response than bluebird nestlings, as predicted by the faster rate of development of the flycatchers. Phytohemag- glutinin response varied between locations for both species. The cell-mediated effects were dynamic in that, in general, the same locations showed similar patterns for each year. Hematocrits steadily increased with age for both species and varied between locations for the bluebird, but not the flycatcher.

Principal Component Analysis Optimization of a PM2.5 Land Use Regression Model with Small Monitoring Network

The use of land-use regression (LUR) techniques for modeling small-scale variations of intraurban air pollution has been increasing in the last decade. The most appealing feature of LUR techniques is the economical monitoring requirements. In this study, principal component analysis (PCA) was employed to optimize an LUR model for PM2.5. The PM2.5 monitoring network consisted of 13 sites, which constrained the regression model to a maximum of one independent variable. An optimized surrogate of vehicle emissions was produced by PCA and employed as the predictor variable in the model. The vehicle emissions surrogate consisted of a linear combination of several traffic variables (e.g., vehicle miles traveled, speed, traffic demand, road length, and time) obtained from a road network used for traffic modeling. The vehicle-emissions surrogate produced by the PCA had a predictive capacity greater (R2=.458) than the traffic variable, Traffic Demand summarized for a 1 km buffer, with best predictive capacity (R2=.341). The PCA-based method employed in this study was effective at increasing the fit of an ordinary LUR model by optimizing the utilization of a PM2.5 dataset from small-n monitoring network. In general, the method used can contribute to LUR techniques in two major ways: 1) by improving the predictive power of the input variable, by substituting a principal component for a single variable and 2) by creating an orthogonal set of predictor variables, and thus fulfilling the no colinearity assumption of the linear regression methods. The proposed PCA method, should be universally applicable to LUR methods and will expand their economical attractiveness.

Black widow spider envenomation in pregnancy

Objective. Little data exist regarding the optimal treatment and outcomes of pregnancies complicated by black widow spider envenomation. Our objective is to evaluate the clinical effects, medical outcomes, and treatment differences between pregnant and nonpregnant women. Methods. This observational study is based on a review of the database maintained by the American Association of Poison Control Centers from 2003 to 2007. Results. Of the 12,640 human black widow spider envenomations reported at 61 poison centers in the United States, 3194 (25.3%) involved women of reproductive age, defined as age 15–45 years of age, with 97 (3.0% of reproductive-age women) being pregnant. Comparing pregnant and nonpregnant women, there were no significant differences in recommended or administered treatments. Pregnant women were more likely than nonpregnant women (OR: 1.84, 95% CI: 1.20–2.83) to have outcomes coded as minor, moderate, or major rather than no effect. Significantly higher percentages of pregnant patients were treated at a healthcare facility where they were either released (36.1% vs. 19.9%, p  < 0.001) or admitted (13.4% vs. 4.0%, p  < 0.001), than nonpregnant women. There were no documented pregnancy losses. Conclusions. Black widow spider envenomation is a rare occurrence in pregnant women and the short-term outcomes appear to be favorable.

Simulated Transport and Retention of Pelagic Fish Eggs during an Irrigation Release in the Pecos River, New Mexico

ABSTRACT The Pecos River between Sumner Dam and Brantley Reservoir (320 km), New Mexico, contains populations of several pelagic-spawning cyprinid fish species, including the federally threatened Pecos bluntnose shiner (Notropis simus pecosensis). Females of this reproductive guild release semi-buoyant eggs that are fertilized and drift, incubate, and hatch on increased flows associated with spring runoff, summer rainstorms, or irrigation releases from Sumner Reservoir. We used artificial eggs (beads) to estimate transport and retention of natural eggs during an irrigation release in five reaches of the Pecos River occupied by bluntnose shiner. Bead retention was highest (1.7–4.5%/km) in the broad complex reaches of upper critical habitat and the quality section (upper 200 km), and bead retention was lowest (0.6%/km) in the narrow, deep, channelized reach of lower critical habitat (60 km). Only 10% of beads were transported more than 50 km from their release location in the reach with highest retention. Modeled spawning events in all five reaches showed highest egg retention of 35% in the reach that also had the highest density of adult Pecos bluntnose shiner (37 km from Cortez Gasline to Acme). The model predicted that during an irrigation release, about 90% of bluntnose shiner eggs produced during a natural spawning event are retained in the upper 250 km of occupied habitat, with only 10% passing downstream into unsuitable habitat or into Brantley Reservoir. We conclude that retention of drifting eggs is greatest during high flows when flood wave attenuation and channel storage are greatest and in broad complex channel reaches, which coincide with existing population centers.