Increased leaf area index and efficiency drive enhanced production under elevated atmospheric [CO2 ] in a pine-dominated stand showing no progressive nitrogen limitation.

Enhancement of net primary production (NPP) in forests as atmospheric [CO2 ] increases is likely limited by the availability of other growth resources. The Duke Free Air CO2 Enrichment (FACE) experiment was located on a moderate-fertility site in the southeastern US, in a loblolly pine (Pinus taeda L.) plantation with broadleaved species growing mostly in mid-canopy and understory. Duke FACE ran from 1994 to 2010 and combined elevated [CO2 ] (eCO2 ) with nitrogen (N) additions. We assessed the spatial and temporal variation of NPP response using a dataset that includes previously unpublished data from 6 years of the replicated CO2 × N experiment and extends to 2 years beyond the termination of enrichment. Averaged over time (1997-2010), NPP of pine and broadleaved species were 38% and 52% higher under eCO2 compared to ambient conditions. Furthermore, there was no evidence of a decline in enhancement over time in any plot regardless of its native site quality. The relation between spatial variation in the response and native site quality was suggested but inconclusive. Nitrogen amendments under eCO2 , in turn, resulted in an additional 11% increase in pine NPP. For pine, the eCO2 -induced increase in NPP was similar above- and belowground and was driven by both increased leaf area index (L) and production efficiency (PE = NPP/L). For broadleaved species, coarse-root biomass production was more than 200% higher under eCO2 and accounted for the entire production response, driven by increased PE. Notably, the fraction of annual NPP retained in total living biomass was higher under eCO2 , reflecting a slight shift in allocation fraction to woody mass and a lower mortality rate. Our findings also imply that tree growth may not have been only N-limited, but perhaps constrained by the availability of other nutrients. The observed sustained NPP enhancement, even without N-additions, demonstrates no progressive N limitation.

Aramchol in patients with nonalcoholic steatohepatitis: a randomized, double-blind, placebo-controlled phase 2b trial.

Nonalcoholic steatohepatitis (NASH), a chronic liver disease without an approved therapy, is associated with lipotoxicity and insulin resistance and is a major cause of cirrhosis and hepatocellular carcinoma. Aramchol, a partial inhibitor of hepatic stearoyl-CoA desaturase (SCD1) improved steatohepatitis and fibrosis in rodents and reduced steatosis in an early clinical trial. ARREST, a 52-week, double-blind, placebo-controlled, phase 2b trial randomized 247 patients with NASH (n = 101, n = 98 and n = 48 in the Aramchol 400 mg, 600 mg and placebo arms, respectively; NCT02279524 ). The primary end point was a decrease in hepatic triglycerides by magnetic resonance spectroscopy at 52 weeks with a dose of 600 mg of Aramchol. Key secondary end points included liver histology and alanine aminotransferase (ALT). Aramchol 600 mg produced a placebo-corrected decrease in liver triglycerides without meeting the prespecified significance (-3.1, 95% confidence interval (CI) -6.4 to 0.2, P = 0.066), precluding further formal statistical analysis. NASH resolution without worsening fibrosis was achieved in 16.7% (13 out of 78) of Aramchol 600 mg versus 5% (2 out of 40) of the placebo arm (odds ratio (OR) = 4.74, 95% CI = 0.99 to 22.7) and fibrosis improvement by ≥1 stage without worsening NASH in 29.5% versus 17.5% (OR = 1.88, 95% CI = 0.7 to 5.0), respectively. The placebo-corrected decrease in ALT for 600 mg was -29.1 IU l-1 (95% CI = -41.6 to -16.5). Early termination due to adverse events (AEs) was <5%, and Aramchol 600 and 400 mg were safe, well tolerated and without imbalance in serious or severe AEs between arms. Although the primary end point of a reduction in liver fat did not meet the prespecified significance level with Aramchol 600 mg, the observed safety and changes in liver histology and enzymes provide a rationale for SCD1 modulation as a promising therapy for NASH and fibrosis and are being evaluated in an ongoing phase 3 program.

Stereotype threat effects in settings with features likely versus unlikely in operational test settings: A meta-analysis.

The stereotype threat literature primarily comprises lab studies, many of which involve features that would not be present in high-stakes testing settings. We meta-analyze the effect of stereotype threat on cognitive ability tests, focusing on both laboratory and operational studies with features likely to be present in high stakes settings. First, we examine the features of cognitive ability test metric, stereotype threat cue activation strength, and type of nonthreat control group, and conduct a focal analysis removing conditions that would not be present in high stakes settings. We also take into account a previously unrecognized methodological error in how data are analyzed in studies that control for scores on a prior cognitive ability test, which resulted in a biased estimate of stereotype threat. The focal sample, restricting the database to samples utilizing operational testing-relevant conditions, displayed a threat effect of d = -.14 (k = 45, N = 3,532, SDδ = .31). Second, we present a comprehensive meta-analysis of stereotype threat. Third, we examine a small subset of studies in operational test settings and studies utilizing motivational incentives, which yielded d-values ranging from .00 to -.14. Fourth, the meta-analytic database is subjected to tests of publication bias, finding nontrivial evidence for publication bias. Overall, results indicate that the size of the stereotype threat effect that can be experienced on tests of cognitive ability in operational scenarios such as college admissions tests and employment testing may range from negligible to small. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Assessment centers versus cognitive ability tests: Challenging the conventional wisdom on criterion-related validity.

Separate meta-analyses of the cognitive ability and assessment center (AC) literatures report higher criterion-related validity for cognitive ability tests in predicting job performance. We instead focus on 17 samples in which both AC and ability scores are obtained for the same examinees and used to predict the same criterion. Thus, we control for differences in job type and in criteria that may have affected prior conclusions. In contrast to Schmidt and Hunter's (1998) meta-analysis, reporting mean validity of .51 for ability and .37 for ACs, we found using random-effects models mean validity of .22 for ability and .44 for ACs using comparable corrections for range restriction and measurement error in the criterion. We posit that 2 factors contribute to the differences in findings: (a) ACs being used on populations already restricted on cognitive ability and (b) the use of less cognitively loaded criteria in AC validation research. (PsycINFO Database Record

Effects of predictor weighting methods on incremental validity.

It is common to add an additional predictor to a selection system with the goal of increasing criterion-related validity. Research on the incremental validity of a second predictor is generally based on forming a regression-weighted composite of the predictors. However, in practice predictors are commonly used in ways other than regression-weighted composites, and we examine the robustness of incremental validity findings to other ways of using predictors, namely, unit weighting and multiple hurdles. We show that there are settings in which the incremental value of a second predictor disappears, and can even produce lower validity than the first predictor alone, when these alternatives to regression weighting are used. First, we examine conditions under which unit weighting will negate gain in predictive power attainable via regression weights. Second, we revisit Schmidt and Hunter's (1998) summary of incremental validity of predictors over cognitive ability, evaluating whether the reported incremental value of a second predictor is different when predictors are unit weighted rather than regression weighted. Third, we analyze data reported in the published literature to discern the frequency with which unit weighting might affect conclusions about whether there is value in adding a second predictor to a first. Finally, we shift from unit weighting to multiple hurdle selection, examining conditions under which conclusions about incremental validity differ when regression weighting is replaced by multiple-hurdle selection. (PsycINFO Database Record

Serum bile acid levels as a predictor for the severity of liver fibrosis in patients with chronic hepatitis C.

Serum bile acids (SBAs) are commonly elevated in cholestatic liver diseases, but it is unclear if SBA levels are also elevated in noncholestatic chronic liver diseases and whether those levels correlate with disease severity. We analysed SBA levels of 135 consecutive patients with chronic hepatitis C virus infection and correlated these levels with the degree of liver fibrosis as determined by liver biopsy. In addition, we assessed the accuracy of SBA levels as a noninvasive predictor for liver fibrosis by its comparison to the patients' FibroTest scores. Two-thirds (90/135 patients, 67%) of the study patients had nonsevere liver fibrosis (Metavir F0-F2), and the others (45/135, 33%) had severe fibrosis or cirrhosis (Metavir F3-F4). The SBA levels were significantly higher in patients with severe fibrosis as compared to nonsevere fibrosis (11.46 ± 10.01 vs 6.37 ± 4.69, P < 0.0001). Furthermore, a receiver operator characteristics curve based on a model that included serum bile acids, age, body mass index, serum AST, glucose and cholesterol levels suggested that this combination reliably predicts the degree of liver fibrosis and is not inferior to the current noninvasive FibroTest score (areas under the curve of 0.837 vs 0.83, respectively, P = 0.87). We conclude that measurement of SBA levels may have a clinical role as a simple noninvasive tool to assess the severity of HCV-induced liver disease. Combined with widely available laboratory parameters, SBA levels can predict disease severity with a high degree of accuracy.

Increased resin flow in mature pine trees growing under elevated CO2 and moderate soil fertility.

Warmer climates induced by elevated atmospheric CO(2) (eCO(2)) are expected to increase damaging bark beetle activity in pine forests, yet the effect of eCO(2) on resin production--the tree's primary defense against beetle attack--remains largely unknown. Following growth-differentiation balance theory, if extra carbohydrates produced under eCO(2) are not consumed by respiration or growth, resin production could increase. Here, the effect of eCO(2) on resin production of mature pines is assessed. As predicted, eCO(2) enhanced resin flow by an average of 140% (P=0.03) in canopy dominants growing in low-nitrogen soils, but did not affect resin flow in faster-growing fertilized canopy dominants or in carbohydrate-limited suppressed individuals. Thus, pine trees may become increasingly protected from bark beetle attacks in an eCO(2) climate, except where they are fertilized or are allowed to become overcrowded.

Increased incidence and mortality associated with skin cancers after cardiac transplant.

Skin cancer incidence has been shown to be increased in the context of transplant-associated immunosuppression. There is, however, limited information specifically about the incidence of skin cancer after cardiac transplantation in the United States. A 10-year retrospective cohort study of 6271 heart transplants at 32 US transplant centers revealed increased postprocedure incidence of nonmelanoma and melanoma skin cancers, especially cutaneous squamous cell carcinoma, for which the incidence increased from 4- to 30-fold compared to the age and gender equivalent general population. Incidence of skin cancer in this study was consistent with prior single-center data regarding cardiac transplant patients. Comparison of all-cause mortality statistics for patients with basal cell carcinoma, squamous cell carcinoma and melanoma, respectively, demonstrated increased mortality associated with melanoma. Skin cancer screening and prophylaxis may be of some utility in reducing morbidity and mortality in cardiac transplant patients.

Fibrotest or Fibroscan for evaluation of liver fibrosis in haemophilia patients infected with hepatitis C.

Non-invasive modalities to estimate fibrosis stage are desirable in hepatitis C-infected haemophilia patients. Previous studies found a high rate of significant fibrosis both by Fibrotest (FT) and Fibroscan (FS) in these patients. To estimate liver fibrosis and to assess the concordance between FT and FS in hepatitis C-infected haemophilia patients. FT and FS were performed at different laboratories and were unaware of the results of the alternative test. Three successive liver stiffness measurements (LSM) were performed at different sites on the liver. Two-validated algorithms were used to improve evaluation of fibrosis by non-invasive methods. Fifty-seven hepatitis C-infected haemophilia patients were evaluated by FT and FS. Acquisition of LSMs was not feasible in two patients: obesity--one, surgical scars--one. Fibrosis stage > or=F2, > or =F3 or =F4 were estimated in about a half, about a third and in 15-20% of the evaluated patients by FS and FT respectively. The corresponding concordance rates and kappa score for fibrosis stage > or =F2, > or =F3 or =F4 between FT and FS were 62%, 69%, 85% and 0.24, 0.32, 0.44 respectively. Using the two aforementioned algorithms, additional 14 patients could be reliably estimated for fibrosis stage > or =F2. High proportion hepatitis C-infected haemophilia patients were estimated with significant or advanced stages of liver fibrosis using both tests. Nevertheless, the agreement between modalities was only fair and improved with more advanced stages of fibrosis. Practical algorithms for the accuracy of FT and FS may improve reliable evaluation of fibrosis in this population.

Canopy nitrogen, carbon assimilation, and albedo in temperate and boreal forests: Functional relations and potential climate feedbacks.

The availability of nitrogen represents a key constraint on carbon cycling in terrestrial ecosystems, and it is largely in this capacity that the role of N in the Earth's climate system has been considered. Despite this, few studies have included continuous variation in plant N status as a driver of broad-scale carbon cycle analyses. This is partly because of uncertainties in how leaf-level physiological relationships scale to whole ecosystems and because methods for regional to continental detection of plant N concentrations have yet to be developed. Here, we show that ecosystem CO(2) uptake capacity in temperate and boreal forests scales directly with whole-canopy N concentrations, mirroring a leaf-level trend that has been observed for woody plants worldwide. We further show that both CO(2) uptake capacity and canopy N concentration are strongly and positively correlated with shortwave surface albedo. These results suggest that N plays an additional, and overlooked, role in the climate system via its influence on vegetation reflectivity and shortwave surface energy exchange. We also demonstrate that much of the spatial variation in canopy N can be detected by using broad-band satellite sensors, offering a means through which these findings can be applied toward improved application of coupled carbon cycle-climate models.

Effects of hydraulic architecture and spatial variation in light on mean stomatal conductance of tree branches and crowns.

In a Pinus taeda L. (loblolly pine) plantation, we investigated whether the response to vapour pressure deficit (D) of canopy average stomatal conductance (G(S)) calculated from sap flux measured in upper and lower branches and main stems follows a hydraulically modelled response based on homeostasis of minimum leaf water potential (Psi(L)). We tested our approach over a twofold range of leaf area index (L; 2-4 m(2) m(-2)) created by irrigation, fertilization, and a combination of irrigation and fertilization relative to untreated control. We found that G(S) scaled well from leaf-level porometery [porometry-based stomatal conductance (g(s))] to branch-estimated and main stem-estimated G(S). The scaling from branch- to main stem-estimated G(S) required using a 45 min moving average window to extract the diurnal signal from the large high-frequency variation, and utilized a light attenuation model to weigh the contribution of upper and lower branch-estimated G(S). Our analysis further indicated that, regardless of L, lower branch-estimated G(S) represented most of the main stem-estimated G(S) in this stand. We quantified the variability in both upper and lower branch-estimated G(S) by calculating the SD of the residuals from a moving average smoothed diurnal. A light model, which incorporated penumbral effects on vertical distribution of direct light, was employed to estimate the variability in light intensity at each canopy level in order to explain the increasing SD of both upper and lower branch-estimated G(S) with light. The results from the light model showed that the upper limit of the variability in individual branch-estimated G(S) could be attributed to incoming light, but not the variation below that upper limit. A porous medium model of water flow in trees produced a pattern of variation below the upper limit that was consistent with the observed variability in branch-estimated G(S). Our results indicated that stems acted to buffer leaf- and branch-level variation and might transmit a less-variable water potential signal to the roots.

Adjustments in hydraulic architecture of Pinus palustris maintain similar stomatal conductance in xeric and mesic habitats.

We investigated relationships between whole-tree hydraulic architecture and stomatal conductance in Pinus palustris Mill. (longleaf pine) across habitats that differed in soil properties and habitat structure. Trees occupying a xeric habitat (characterized by sandy, well-drained soils, higher nitrogen availability and lower overstory tree density) were shorter in stature and had lower sapwood-to-leaf area ratio (A(S):A(L)) than trees in a mesic habitat. The soil-leaf water potential gradient (psiS - psiL) and leaf-specific hydraulic conductance (kL) were similar between sites, as was tissue-specific hydraulic conductivity (Ks) of roots. Leaf and canopy stomatal conductance (gs and Gs, respectively) were also similar between sites, and they tended to be somewhat higher at the xeric site during morning hours when vapour pressure deficit (D) was low. A hydraulic model incorporating tree height, A(S):A(L) and psiS-psiL accurately described the observed variation in individual tree G(Sref) (G(S) at D = 1 kPa) across sites and indicated that tree height was an important determinant of G(Sref) across sites. This, combined with a 42% higher root-to-leaf area ratio (A(R):A(L)) at the xeric site, suggests that xeric site trees are hydraulically well equipped to realize equal--and sometimes higher potential for conductance compared with trees on mesic sites. However, a slightly more sensitive stomatal closure response to increasing D observed in xeric site trees suggests that this potential for higher conductance may only be reached when D is low and when the capacity of the hydraulic system to supply water to foliage is not greatly challenged.

Acute hepatitis B in the era of immunisation: pitfalls in the identification of high risk patients.

BACKGROUND: Since the adoption of a universal hepatitis B immunisation strategy, the reported incidence of acute hepatitis B has declined dramatically worldwide including in Israel. However, new cases of acute hepatitis B still occur. The aim of this study was to describe the incidence of acute hepatitis B in a referral area, routes of transmission, and outcome. METHODS: The charts of all new hepatitis B patients, who visited the clinic in the years 2002 and 2003 (January 2002 to December 2003), were reviewed. The main criteria for a diagnosis of acute hepatitis B were transient increase of alanine transaminase activity, and hepatitis B surface antigen seroconversion. RESULTS: Twenty nine men and seven women were diagnosed with acute hepatitis B infection during the study period. Two patients were previously vaccinated with hepatitis B vaccine. One case of hepatitis D coinfection was reported. The incidence of acute hepatitis B in the referral area was estimated as 2.25 per 100,000 adult population. Mean age was 36 years (17-75). Twenty one patients (18 men and 3 women) acquired the virus through unprotected sexual contact, and seven patients through iatrogenic exposure. Thirty three patients underwent spontaneous seroconversion while three patients became chronic carriers. CONCLUSIONS: Despite a universal immunisation policy, frequent cases of acute hepatitis B in Israel are still seen. High risk heterosexual activity and iatrogenic exposure seem to be the commonest routes of transmission. Further recommendations regarding vaccination policy are discussed.

To induce or not to induce: do patients at greatest risk for fatal rejection benefit from cytolytic induction therapy?

BACKGROUND: Induction immunosuppression utilizing lymphocytolytic agents in the early peri-operative period has a number of theoretical and practical advantages and disadvantages. However, the efficacy of cytolytic agents as induction therapy remains unproven. METHODS: To assess the current impact of induction therapy in heart transplantation, we queried a multi-institutional database regarding the frequency of use, type of agent, duration of therapy and outcomes of 6,553 patients transplanted from 1990 to 2001. A study group of 5,897 patients were identified who survived the first 48 hours post-transplant and received either no induction therapy (n = 4,161) or induction with OKT3 or anti-thymocyte preparations (n = 1,736). RESULTS: By multivariate analysis, risk factors for rejection death were identified and then applied to a model of overall mortality. Among patients with a 1-year risk of rejection death at >5%, induction therapy provided a survival advantage, but survival with induction was decreased when the risk of rejection death was <2%. Specific patient sub-sets that received a survival benefit in the current era with induction included younger patients of black race with >/=4 HLA mismatches and long-term (>6 months) support on a ventricular assist device (VAD). CONCLUSIONS: Use and application of induction therapy continues to be controversial in heart transplantation. At present, this approach appears to be beneficial in selected patients who are at high risk for rejection death, but likely detrimental in patients who are at low risk for rejection death. Those with a combination of longer term VAD support, of black ethnicity, and having extensive HLA mismatching are most likely to benefit from cytolytic induction therapy.

Electrically conductive 2D-PAN-containing surfaces as a culturing substrate for neurons.

In the present contribution we report on a novel route to synthesize 2D-polyaniline (2D-PAN) on sulfonated-poly(styrene) (SPS) templates by allowing first monomer assembly followed by chemical oxidation to achieve polymerization. We show that Aplysia neurons grown on 2D-PAN exhibit an unusual growth pattern and adhesion to this conducting substrate that is manifested by the formation of giant lamellipodia. The lamellipodial domains are characterized by small gap between the plasma membrane and the 2D-PAN substrate (ca. 30 nm) and actin rich skeleton resembling the skeleton of growth cones. This behavior is characteristic to uniform substrates containing only 2D-PAN. However, in patterned substrates containing additionally poly(L-lysine) Aplysia neurons prefer to extend new neurites on the poly(L-lysine) domains.

Carbon dioxide and water vapor exchange in a warm temperate grassland.

Grasslands cover about 40% of the ice-free global terrestrial surface, but their contribution to local and regional water and carbon fluxes and sensitivity to climatic perturbations such as drought remains uncertain. Here, we assess the direction and magnitude of net ecosystem carbon exchange (NEE) and its components, ecosystem carbon assimilation ( A(c)) and ecosystem respiration ( R(E)), in a southeastern United States grassland ecosystem subject to periodic drought and harvest using a combination of eddy-covariance measurements and model calculations. We modeled A(c) and evapotranspiration (ET) using a big-leaf canopy scheme in conjunction with ecophysiological and radiative transfer principles, and applied the model to assess the sensitivity of NEE and ET to soil moisture dynamics and rapid excursions in leaf area index (LAI) following grass harvesting. Model results closely match eddy-covariance flux estimations on daily, and longer, time steps. Both model calculations and eddy-covariance estimates suggest that the grassland became a net source of carbon to the atmosphere immediately following the harvest, but a rapid recovery in LAI maintained a marginal carbon sink during summer. However, when integrated over the year, this grassland ecosystem was a net C source (97 g C m(-2) a(-1)) due to a minor imbalance between large A(c) (-1,202 g C m(-2) a(-1)) and R(E) (1,299 g C m(-2) a(-1)) fluxes. Mild drought conditions during the measurement period resulted in many instances of low soil moisture (theta<0.2 m(3)m(-3)), which influenced A(c) and thereby NEE by decreasing stomatal conductance. For this experiment, low theta had minor impact on R(E). Thus, stomatal limitations to A(c) were the primary reason that this grassland was a net C source. In the absence of soil moisture limitations, model calculations suggest a net C sink of -65 g C m(-2) a(-1) assuming the LAI dynamics and physiological properties are unaltered. These results, and the results of other studies, suggest that perturbations to the hydrologic cycle are key determinants of C cycling in grassland ecosystems.

Triiodothyronine and interleukin-6 (IL-6) induce expression of HGF in an immortalized rat hepatic stellate cell line.

BACKGROUND/AIMS: Despite its being considered a primary mitogen for hepatocytes, triiodothyronine (T3) has no effect on the proliferation of hepatocytes in vitro, and in our studies, induces significant in vivo hepatocyte proliferation only during liver injury. We hypothesized that T3 may affect hepatocytes proliferation indirectly, by inducing other cells in the liver to secrete hepatic mitogens. METHODS: In vivo studies: Lipopolysaccharide, T3 and a combination of the two were injected into rats, and hepatocyte proliferation was determined by PCNA staining and mitotic index. IN VITRO STUDIES: a rat hepatic stellate cell line (HSC-6T) was cultured with T3, IL-6 and a combination of the two, and we assessed the effect of these cytokine/hormone combinations on the cell proliferation and on secretion of IL-6 and HGF, measured by ELISA. Expression of thyroid hormone receptors was assessed by RT-PCR. RESULTS: In vivo: T3, together with lipopolysaccharide, enhances PCNA staining and the mitotic index of hepatocytes in the treated rats. In vitro: the hepatic stellate cell line expresses thyroid hormone receptor alpha 1, but not beta 1. Proliferation of stellate cells is not affected by T3, with or without IL-6. T3 has no effect on secreted levels of IL-6 in the stellate cell line. Hepatic stellate cells cultured with T3 and IL-6 show significantly increased amounts of secreted HGF after 48 h in culture. CONCLUSION: T3 may induce hepatocyte proliferation in vivo during injury by turning on expression of HGF in stellate cells and acting together with IL-6.

Water deficits and hydraulic limits to leaf water supply.

Many aspects of plant water use -- particularly in response to soil drought -- may have as their basis the alteration of hydraulic conductance from soil to canopy. The regulation of plant water potential (Psi) by stomatal control and leaf area adjustment may be necessary to maximize water uptake on the one hand, while avoiding loss of hydraulic contact with the soil water on the other. Modelling the changes in hydraulic conductance with pressure gradients in the continuum allows the prediction of water use as a function of soil environment and plant architectural and xylem traits. Large differences in water use between species can be attributed in part to differences in their 'hydraulic equipment' that is presumably optimized for drawing water from a particular temporal and spatial niche in the soil environment. A number of studies have identified hydraulic limits as the cause of partial or complete foliar dieback in response to drought. The interactions between root:shoot ratio, rooting depth, xylem properties, and soil properties in influencing the limits to canopy water supply can be used to predict which combinations should optimize water use in a given circumstance. The hydraulic approach can improve our understanding of the coupling of canopy processes to soil environment, and the adaptive significance of stomatal behaviour.