Modeling superimposed preeclampsia using Ang II (Angiotensin II) infusion in pregnant stroke-prone spontaneously hypertensive rats

Hypertensive disorders of pregnancy are the second leading cause of maternal deaths worldwide. Superimposed preeclampsia is an increasingly common problem and often associated with impaired placental perfusion. Understanding the underlying mechanisms and developing treatment options are crucial. The pregnant stroke-prone spontaneously hypertensive rat has impaired uteroplacental blood flow and abnormal uterine artery remodeling. We used Ang II (angiotensin II) infusion in pregnant stroke-prone spontaneously hypertensive rats to mimic the increased cardiovascular stress associated with superimposed preeclampsia and examine the impact on the maternal cardiovascular system and fetal development. Continuous infusion of Ang II at 500 or 1000 ng/kg per minute was administered from gestational day 10.5 until term. Radiotelemetry and echocardiography were used to monitor hemodynamic and cardiovascular changes, and urine was collected prepregnancy and throughout gestation. Uterine artery myography assessed uteroplacental vascular function and structure. Fetal measurements were made at gestational day 18.5, and placentas were collected for histological and gene expression analyses. The 1000 ng/kg per minute Ang II treatment significantly increased blood pressure (P<0.01), reduced cardiac output (P<0.05), and reduced diameter and increased stiffness of the uterine arteries (P<0.01) during pregnancy. The albumin:creatinine ratio was increased in both Ang II treatment groups (P<0.05; P<0.0001). The 1000 ng/kg per minute–treated fetuses were significantly smaller than vehicle treatment (P<0.001). Placental expression of Ang II receptors was increased in the junctional zone in 1000 ng/kg per minute Ang II–treated groups (P<0.05), with this zone showing depletion of glycogen content and structural abnormalities. Ang II infusion in pregnant stroke-prone spontaneously hypertensive rats mirrors hemodynamic, cardiac, and urinary profiles observed in preeclamptic women, with evidence of impaired fetal growth

Disaggregative and individual-tree growth models in theory and application

Disaggregative and individual-tree/distance-independent modeling methods are compared and contrasted. Differences between the two are related to differences in functional and apparent resolution and may be illustrated using aggregation theory. When considering models of different levels of resolution describing a given phenomenon, invariance with respect to the aggregation implied (symmetry) may be important to both the modeler and the user alike. In the absence of invariance between stand and tree-level predictions, conflicting predictions arise. Some limitations of whole-stand models are also present in disaggregative models, however one way to bridge the gap between traditional individual-tree/distance-independent and whole stand models may be to use the individual-tree growth function in concert with the whole stand projection model as a disaggregator of growth. While the use of individual-tree models in this way is intuitively appealing, findings in this paper indicate that the more traditional, unconstrained tree growth functions may better predict growth of individual-trees. Five-year growth data from 105 Douglas-fir stands in western Oregon were used to compare various individual-tree, disaggregative and whole stand models at both the stand and tree level. Traditional approaches to disaggregation were unable to match the individual tree growth rate functions for predicting five-year growth rate of individual-trees. Both suffered due to a lack of any index of tree position, lack of a crown ratio component, and reliance on linearity between growth and tree dimension. The very simple proportional allocation approach based on tree dimension was most unsatisfactory. It remains to be seen if these trends will also hold for longer term projections of growth. At the stand level, the symmetric disaggregative model reduces to a simple whole stand approach to modeling. With respect to whole stand predictions, the individual-tree gross basal area growth model resulted in lower mean squared error than the aggregate (whole stand) model. There is a loss of information associated with the aggregation of tree data to predict growth. This loss of information may be responsible for the differences in mean squared error. Some of this difference may also be attributed to the inclusion of crown ratio in individual-tree predictions of growth

Development of tree height and diameter growth equations for mid-Willamette Valley Douglas-fir

Equations for predicting height growth, basal area growth and diameter inside bark are presented for Douglas-fir. Basal area growth equations for grand fir are also presented. The growth models were developed for use in an individual tree/distance independent growth simulator. Various model forms and measures of competitive stress were compared in both the height and basal area growth models. The height growth equation is a function of crown ratio and height divided by dominant stand height. Basal area growth is a function of tree diameter, crown ratio, crown competition at the plot level, stand basal area and either site index or predicted height growth. The diameter inside bark equation, used in backdating tree diameters, is a nonlinear function of diameter outside bark

Ordering our world: the quest for traces of temporal organization in autobiographical memory

An experiment examined the idea, derived from the Self Memory System model (Conway & Pleydell-Pearce, 2000), that autobiographical events are sometimes tagged in memory with labels reflecting the life era in which an event occurred. The presence of such labels should affect the ease of judgments of the order in which life events occurred. Accordingly, 39 participants judged the order of two autobiographical events. Latency data consistently showed that between-era judgments were faster than within-era judgments, when the eras were defined in terms of either: (a) college versus high school, (b) academic quarter within year, or (c) academic year within school. The accuracy data similarly supported the presence of a between-era judgment effect for the college versus high school dichotomy

Evaluation of individual-tree and disaggregative prediction methods for Douglas-fir stands in western Oregon

The efficiency of six disaggregative methods and two individual-tree methods was evaluated in terms of their ability to predict 5-year basal area increment for Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) stands in western Oregon. Models were developed for predicting gross stand basal-area increment and individual-tree diameter increment. In addition, models were developed to disaggregate the active increment prediction methods to the tree level. Passive and active prediction schemes were evaluated for both the tree and stand levels. Generally, the individual-tree approach was superior to the disaggregative approach for prediction of both stand and tree growth. This was less evident, however, when crown ratio was eliminated from the individual-tree models. This suggests that at least some of the disparity between the two is due to the presence of crown ratio in an individual-tree passive aggregation approach. The additive disaggregation approach appeared to be best suited to young stands (less than 50 years of age). The linearity assumption required for this particular model appeared to be violated for older stands with larger trees. Generally, the two whole-stand, gross-growth models used in this study were inferior to the individual-tree method for predicting gross basal area growth for one period.Keywords: individual-tree prediction methods, basal-area increment, disaggregative prediction methods, tree growth, stand growth, crown ratio, Douglas-fir (Pseudotsuga menziesii)Keywords: individual-tree prediction methods, basal-area increment, disaggregative prediction methods, tree growth, stand growth, crown ratio, Douglas-fir (Pseudotsuga menziesii

Extensive recombination detected among beak and feather disease virus isolates from breeding facilities in Poland

Beak and feather disease virus (BFDV) causes the highly contagious, in some cases fatal, psittacine beak and feather disease in parrots. The European continent has no native parrots, yet in the past has been one of the world’s biggest importers of wild-caught exotic parrot species. Following the banning of this practice in 2007, the demand for exotic pet parrots has largely been met by established European breeding facilities, which can also supply buyers outside Europe. However, the years of unregulated importation have provided numerous opportunities for BFDV to enter Europe, meaning the likelihood of birds within captive breeding facilities being BFDV positive is high. This study examined the BFDV status of such facilities in Poland, a country previously shown to have BFDV among captive birds. A total of 209 birds from over 50 captive breeding facilities across Poland were tested, and 43 birds from 18 different facilities tested positive for BFDV. The full BFDV genomes from these 43 positive birds were determined, and phylogenetic analysis revealed that these samples harboured a relatively high degree of diversity and that they were highly recombinant. It is evident that there have been multiple introductions of BFDV into Poland over a long period of time, and the close association of different species of birds in the captive environment has probably facilitated the evolution of new BFDV strains through recombination.Web of Scienc

Thinning ponderosa pine (Pinus ponderosa) stands reduces mortality while maintaining stand productivity

We analyzed 45 years of data collected from three ponderosa pine (Pinus ponderosa Douglas ex P. Lawson & C. Lawson) levels-of-growing-stock installations in Oregon (OR) and northern California (CA), USA, to determine the effect of stand density regimes on stand productivity and mortality. We found that periodic annual increment (PAI) of diameter, basal area (BA), volume, and aboveground dry mass were significantly related to stand density index (SDI) and stand age at start of the period; the quadratic trends varied among sites. Precipitation departure from the normal for each period explained a significant amount of residual variation in all PAI variables except diameter. BA production did not change significantly as SDI exceeded 270 trees.ha⁻¹ at the OR sites and 320 trees.ha⁻¹ at the CA site. Stand productivity was the highest at Elliot Ranch (CA) and the least at Blue Mountains (OR). A similar trend held in growth efficiency under lower stand densities (SDI < 600). Most of the mortality was caused by Dendroctonus bark beetles in stands that exceeded SDI of 500 trees.ha⁻¹. Limiting SDI was about 900 trees.ha⁻¹, although plots at Elliot Ranch reached much higher than that. The results demonstrate that silvicultural control of stand density can be a powerful tool for reducing bark beetle caused mortality without sacrificing stand productivity.Keywords: Dynamics, United States, Beetle, Western, Forests, Climate changeKeywords: Dynamics, United States, Beetle, Western, Forests, Climate chang

76-Year Decline and Recovery of Aspen Mediated by Contrasting Fire Regimes: Long-Unburned, Infrequent and Frequent Mixed-Severity Wildfire

Quaking aspen (Populus tremuloides) is a valued, minor component on northeastern California landscapes. It provides a wide range of ecosystem services and has been in decline throughout the region for the last century. This decline may be explained partially by the lack of fire on the landscape due to heavier fire suppression, as aspen benefit from fire that eliminates conifer competition and stimulates reproduction through root suckering. However, there is little known about how aspen stand area changes in response to overlapping fire. Our study area in northeastern California on the Lassen, Modoc and Plumas National Forests has experienced recent large mixed-severity wildfires where aspen was present, providing an opportunity to study the re-introduction of fire. We observed two time periods; a 52-year absence of fire from 1941 to 1993 preceding a 24-year period of wildfire activity from 1993 to 2017. We utilized aerial photos and satellite imagery to delineate aspen stands and assess conifer cover percent. We chose aspen stands in areas where wildfires overlapped (twice-burned), where only a single wildfire burned, and areas that did not burn within the recent 24-year period. We observed these same stands within the first period of fire exclusion for comparison (i.e., 1941–1993). In the absence of fire, all aspen stand areas declined and all stands experienced increases in conifer composition. After wildfire, stands that burned experienced a release from conifer competition and increased in stand area. Stands that burned twice or at high severity experienced a larger removal of conifer competition than stands that burned once at low severity, promoting expansion of aspen stand area. Stands with less edge:area ratio also expanded in area more with fire present. Across both time periods, stand movement, where aspen stand footprints were mostly in new areas compared to footprints of previous years, was highest in smaller stands. In the fire exclusion period, smaller stands exhibited greater loss of area and changes in location (movement) than in the return of fire period, highlighting their vulnerability to loss via succession to conifers in the absence of disturbances that provide adequate growing space for aspen over time

Mapping localized surface plasmons within silver nanocubes using cathodoluminescence hyperspectral imaging

Localized surface plasmons within silver nanocubes less than 50 nm in size are investigated using high resolution cathodoluminescence hyperspectral imaging. Multivariate statistical analysis of the multidimensional luminescence dataset allows both the identification of distinct spectral features in the emission and the mapping of their spatial distribution. These results show a 490 nm peak emitted from the cube faces, with shorter wavelength luminescence coming from the vertices and edges; this provides direct experimental confirmation of theoretical predictions

Changes in cortical bone response to high-fat diet from adolescence to adulthood in mice

UnlabelledDiabetic obesity is associated with increased fracture risk in adults and adolescents. We find in both adolescent and adult mice dramatically inferior mechanical properties and structural quality of cortical bone, in agreement with the human fracture data, although some aspects of the response to obesity appear to differ by age.IntroductionThe association of obesity with bone is complex and varies with age. Diabetic obese adolescents and adult humans have increased fracture risk. Prior studies have shown reduced mechanical properties as a result of high-fat diet (HFD) but do not fully address size-independent mechanical properties or structural quality, which are important to understand material behavior.MethodsCortical bone from femurs and tibiae from two age groups of C57BL/6 mice fed either HFD or low-fat diet (LFD) were evaluated for structural and bone turnover changes (SEM and histomorphometry) and tested for bending strength, bending stiffness, and fracture toughness. Leptin, IGF-I, and non-enzymatic glycation measurements were also collected.ResultsIn both young and adult mice fed on HFD, femoral strength, stiffness, and toughness are all dramatically lower than controls. Inferior lamellar and osteocyte alignment also point to reduced structural quality in both age groups. Bone size was largely unaffected by HFD, although there was a shift from increasing bone size in obese adolescents to decreasing in adults. IGF-I levels were lower in young obese mice only.ConclusionsWhile the response to obesity of murine cortical bone mass, bone formation, and hormonal changes appear to differ by age, the bone mechanical properties for young and adult groups are similar. In agreement with human fracture trends, adult mice may be similarly susceptible to bone fracture to the young group, although cortical bone in the two age groups responds to diabetic obesity differently