text
string | predicted_class
string | confidence
float16 |
|---|---|---|
In-country data requirements by the Mexican regulatory system are of a confirmatory nature, given that the standard process to demonstrate crop safety for any commercial GM crop includes a stringent battery of rigorous scientific evaluations and independent regulatory reviews by most grain-importing and cultivating countries (Nakai et al. 2015). By the time a GM crop product is introduced into the Mexican regulatory system, extensive evaluation has already taken place in other world areas. These evaluations examine the potential for food, feed, and environmental risk. Phenotypic and agronomic characterization of GM crops relative to conventional crops provides a comparative context that is used within the natural variation of the crop to establish “familiarity” (Nickson and Horak 2006). Ultimately, this comparative assessment is used to assess potential risks that may be hypothesized regarding the cultivation of GM crops (Horak et al. 2007, 2015; Raybould et al. 2012; Sammons et al. 2014) and that are assessed on the basis of specific environmental protection goals (Nickson 2008). The concept of familiarity is useful to decision makers and regulators because it comes from preexisting general knowledge of the biology and agronomic characteristics of a crop, previous field cultivation results, expert opinions, historical agronomic experience, and the characteristics of the trait(s) introduced, the receiving environment, and their interactions (Nickson and Horak 2006). For example, Raybould et al. (2012) laid out a possible scenario by which an ecological harm may arise from cultivating GM crops when some of the seed produced is dispersed into a new environment, establishing new populations that may reduce the abundance of the original crop population or natural vegetation. In cases where maize is the receiving crop, familiarity would help dismiss this scenario because maize cannot survive outside of cultivation given that any weediness characteristics have been eliminated during the domestication and selection processes (Gould 1968; Keeler 1989; Martínez-Soriano et al. 2002).
|
review
| 99.7 |
Mexico is a “mega-diverse” country and is one of more than 17 nations that together contain nearly 70 % of the global diversity of plant and animal species (CONABIO 2009). Several ecoregions have been defined in Mexico based on biodiversity criteria (INEGI-CONABIO-INE 2008; Wiken et al. 2011). For conservation purposes, an ecoregion is defined as a large unit of land containing a geographically characteristic assemblage of species, natural communities, and environmental conditions. The boundaries of an ecoregion are not fixed and sharp, but rather encompass an area where important ecological and evolutionary processes generally interact. In contrast, field studies to characterize GM crops are typically implemented in areas devoted to agricultural production. These agricultural areas have relatively homogeneous characteristics (e.g., climate, soils, water availability, infrastructure) and are contained within the larger, usually more heterogenous, ecoregions. Field studies with GM plant materials are implemented under confinement conditions as a biosafety measure. There are no international standards for conducting confined field trials (CFTs), and national regulations and guidance vary by country with regard to trial design, number of sites, and duration (Garcia-Alonso et al. 2014). After almost two decades of cultivation of GM crops worldwide, a conceptual model and methodological scheme has been proposed in which it is possible to utilize data generated in one region to assess environmental risk for another region (Garcia-Alonso et al. 2014; Horak et al. 2015; Ahmad et al. 2016). Results from field studies obtained from multiple geographies for GM soybean (Horak et al. 2015) and GM maize (Nakai et al. 2015; Ahmad et al. 2016) demonstrate the utility of generating relevant data that are transportable across regions for the ERA of GM crops. This approach can be readily applied in practice when the assessment endpoints are demonstrably similar to those of other regions where new CFTs are being considered. Currently in Mexico, it is not possible to use data generated in one ecoregion for approvals in another. As described above, however, agricultural fields are typically located in disturbed environments that tend to be homogeneous even though they may be in different ecoregions.
|
review
| 99.8 |
GM crops have been grown commercially for more than 20 years. By 2014, 181.5 million hectares of GM crops were planted in 29 countries by more than 18 million growers (James 2014; Aldemita et al. 2015). In general, the rapid adoption of GM crops by farmers is due to their benefits such as higher yield potential, obtained by protecting against insects pests and weeds, and lower production costs (Areal et al. 2013; Solleiro Rebolledo and Castañón Ibarra 2013). In both developed and developing countries, economic profits associated with GM crops are usually higher than those achieved with conventional varieties due to the combination of yield increases and reduction of production costs (Finger et al. 2011; Areal et al. 2013; Klümper and Qaim 2014). Insect-resistant (IR) crops increase farmers’ profits as a result of higher yields and lower expenditure on insecticides (Qaim 2009). Herbicide-tolerant (HT) crops facilitate implementation of more cost-effective and efficacious weed control programs by enabling application of broad-spectrum herbicides (Klümper and Qaim 2014).
|
review
| 99.9 |
The use of improved varieties and hybrids combined with appropriate agronomic practices has helped to reduce crop losses due to pests and diseases (Oerke 2006; Blanco et al. 2014; Vargas-Parada 2014). However, in spite of these improvements, yield losses of up to 31 % of maize production have been reported due to pests (insects, weeds) and diseases (Oerke 2006). In Mexico, where approximately 6–8 million hectares are planted to corn annually, loss in maize production due to insects, diseases, and other pests is estimated as high as 30 % (Oerke 2006). A recent survey in Mexico documented that 3000 tons of insecticide active ingredients are required each year to reduce damage by fall armyworm (Spodoptera frugiperda Smith), corn earworm (Helicoverpa zea Boddie), and cutworms (Agrotis ipsilon Hufnagel) (Blanco et al. 2014). Mexico’s current use of pesticides is the highest per unit area in North America, at 4.5 kg ha−1 compared to 2.2 and 1 kg ha−1 for the USA and Canada, respectively (Stokstad 2013). The task to increase maize production in Mexico requires the use and adoption of technologies and best practices of modern agriculture (Vargas-Parada 2014). These include conventional improved seed, GM IR and HT varieties with higher yield potential, and best management practices for the control of insects, pathogens, and weeds and tolerance to abiotic stresses (Oerke 2006; Vargas-Parada 2014). Furthermore, greater adoption of integrated pest management (IPM) systems combined with the development and availability of pest-resistant maize varieties should reduce the use of conventional pesticides and help Mexico to reduce annual corn grain imports (Blanco et al. 2014).
|
review
| 99.2 |
The objectives of this analysis were, first, to characterize and assess three maize GM hybrids—MON-89Ø34-3 × MON-88Ø17-3 (three stacked IR traits plus a single HT trait), MON-89Ø34-3 × MON-ØØ6Ø3-6 (two stacked IR traits plus a single HT trait), and MON-ØØ6Ø3-6 (single HT trait)—grown at several sites in Mexico for evidence of biologically meaningful agronomic and phenotypic differences or adverse ecological effects due to the introgression of IR and/or HT biotech traits (ERA). The second objective was to confirm biological efficacy in terms of plant response of MON-89Ø34-3 × MON-88Ø17-3 and MON-89Ø34-3 × MON-ØØ6Ø3-6 maize hybrids against lepidopteran and coleopteran insect pests, and to assess tolerance to glyphosate-based herbicides and efficacy of weed management programs by all three maize hybrids.
|
study
| 100.0 |
Study sites in maize production areas were located within five ecoregions: (i) 9.5.1.2 = Tamaulipas coastal plain with xerophile vegetation or without apparent vegetation; (ii) 10.2.2.8 = floodplains of the Yaqui, Mayo, and Fuerte Rivers with xerophile shrubs and mesquite; (iii) 10.2.3.3 = floodplains and rolling hills of the Vizcaíno and Magdalena Deserts with xerophile sarco-sarcocrassicaule and halophytic vegetation; (iv) 10.2.4.1 = central plains of the Chihuahuan Desert with xerophile-halophytic microphyllus vegetation; and (v) 14.3.1.2 = Sinaloa coastal plain with low thorny forest (INEGI-CONABIO-INE 2008) (Supplementary Table 1, Fig. 1). Thirty-six studies, 19 Experimental Phase (smaller trials) and 17 Pilot Phase (larger trials), were conducted across maize production regions of the Mexican states of Sinaloa, Sonora, Chihuahua, Coahuila and Durango (Comarca Lagunera), Tamaulipas, and Baja California Sur during the 2009–2013 crop seasons (Supplementary Table 2).Fig. 1Map of level IV ecological regions (ecoregions) of Mexico where GM field studies were conducted during 2009–2013
|
study
| 100.0 |
The test materials were GM maize hybrids MON-89Ø34-3 × MON-88Ø17-3, MON-89Ø34-3 × MON-ØØ6Ø3-6, and MON-ØØ6Ø3-6, and the control materials were corresponding conventional (non-GM) isohybrids. Within each study, the three GM maize hybrids and the conventional maize control hybrid were all in the same hybrid (genetic background). At all but one site (Chihuahua), the hybrids were in a genetic background broadly adapted to the environmental conditions of northern Mexican states; at Chihuahua, an early-maturing hybrid background was used. GM hybrid MON-89Ø34-3 × MON-88Ø17-3 expresses three Bt proteins (Cry1A.105, Cry2Ab2, and Cry3Bb1) that confer resistance against aboveground lepidopteran insect pests and belowground local Diabrotica species. It also expresses the 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) protein, which confers tolerance to glyphosate herbicide. GM hybrid MON-89Ø34-3 × MON-ØØ6Ø3-6 expresses two Bt proteins (Cry1A.105 and Cry2Ab2) that confer resistance against aboveground lepidopteran insects pests, and also expresses the EPSPS protein. GM hybrid MON-ØØ6Ø3-6 expresses only the EPSPS protein.
|
study
| 99.94 |
Experimental Phase plot size ranged from 12 to 384 m2, and Pilot Phase plot size ranged from 398.7 to 4128 m2 (Supplementary Table 2). The main soil textures varied across locations and included clay, silty clay, clay loam, sandy loam, sandy clay loam, and sandy silt. Row spacing varied from 0.65 to 0.92 m, with a seeding rate of 5 to 10 seeds per meter and seed planting depth of 2 to 9 cm. Plot management was according to the recommendations by INIFAP-CIRNO for maize (Mendoza et al. 2003). Crop management practices included seedbed soil preparation, fertilization, irrigation, and insect and weed control according to regional best practices. Agronomic practices were conducted uniformly across all entries within a study in the Experimental Phase trials in order to eliminate an additional source of variation on the agronomic and phenotypic characteristics. However, in the Pilot Phase trials, insect and weed control practices were conducted according to each material’s phenotype, i.e., the IR/HT hybrids MON-89Ø34-3 × MON-88Ø17-3 and MON-89Ø34-3 × MON-ØØ6Ø3-6 GM did not require conventional insecticide applications for target lepidopteran insect pests, but MON-ØØ6Ø3-6 (HT only) and the conventional hybrid required two to four application of conventional insecticides to control lepidopteran pests across most sites. Weed control was also different between the GM hybrids (all HT) and the conventional control hybrid. Across all sites, one or two over-the-top applications of Faena Fuerte® with Transorb® 1 (540 g a.i. L−1), a glyphosate-containing herbicide, were made on the three GM hybrids at rates of 2 to 4 L ha−1. Weed control for the conventional control was mechanical (cultivator or manual) and/or by applications of selective herbicides. Subsequently, weed control was evaluated at approximately 11, 20, and 30 days after herbicide treatment in all of the studies.
|
study
| 99.94 |
GM maize hybrids MON-89Ø34-3 × MON-88Ø17-3, MON-89Ø34-3 × MON-ØØ6Ø3-6, and MON-ØØ6Ø3-6 and a corresponding conventional isohybrid control were planted in each of 36 studies (19 Experimental Phase, 17 Pilot Phase) in a randomized complete block design (RCBD) with three to four replications and up to four locations per ecoregion per year (Supplementary Tables 1 and 2). Twelve agronomic and phenotypic characteristics were evaluated throughout the season (Supplementary Table 3). In addition, plant response to target insect pests (i.e., stalk borer tunnel length and tunnel number, Diabrotica root damage, corn earworm damage, and Spodoptera leaf damage) were evaluated according to standard methods (Davis et al. 1992; Oleson et al. 2005). When present, cutworm (Agrotis and/or Spodoptera spp.) seedling damage was also documented (Supplementary Table 3). Weed control levels (% of total weed population eliminated) by total applications of glyphosate vs. mechanical weed control treatments were documented at multiple locations. Agronomic, phenotypic, and insect damage data collected from each individual study were subject to an analysis of variance (ANOVA). The means, standard errors, and sample sizes of the test and control hybrids for agronomic, phenotypic, and insect damage measurements from each study were generated from the statistical analyses of individual studies and included in a meta-analysis.
|
study
| 100.0 |
A meta-analysis uses standardized differences, i.e.,1\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$d = (\bar{y}_{\text{test}} - \bar{y}_{\text{control}} )/s_{\text{p}}$$\end{document}d=(y¯test-y¯control)/spwhere \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\bar{y}_{\text{test}}$$\end{document}y¯test and \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\bar{y}_{\text{control}}$$\end{document}y¯control are the sample mean of the test and control, respectively, and s p is the pooled standard deviation, which is calculated from the individual test and control standard deviations. Thus, the standard errors were converted into standard deviations. The database spreadsheets were imported into the software Comprehensive Meta-Analysis™ (version 2, 2011; Biostat™, Englewood, NJ). Separate meta-analyses were conducted for each of the three test materials within each of the two regulatory phases (Experimental and Pilot) using random-effects models (Cochran and Cox 1957). In some cases, there were studies where the standard deviation for the test and/or the control was zero. These studies were excluded from the meta-analysis because s p in Eq. (1) is assumed to be calculated from nonzero standard deviations. The meta-analysis used standardized differences from each individual study to compute a combined study effect. The combined study effect is a weighted standardized difference between test and control across studies, and the weights are functions of the sample sizes (Hedges and Olkin 1985). A random-effects model was used in each meta-analysis based on the assumption that the material effect interacts with the changing environments (sites), which is a common assumption in agronomic studies. The combined study effect obtained under the random-effects model is an estimate of the overall effect (standardized difference between test and control) across all potential environments. (The significance testing of this overall effect took the material-by-site interaction effect into account.) A 95 % confidence interval along with the p value was also obtained to describe the combined study effect. If the 95 % confidence interval contains zero, then the standardized difference favors neither the test nor the control. If the interval does not contain zero and is positive, then the standardized difference favors the test (test minus control is positive); if the interval does not contain zero and is negative, then the standardized difference favors the control (test minus control is negative). Statistical significance is defined by a p value <0.05. If the p value is less than 0.05, then the combined study effect is significantly different from zero, which means that the test and control are significantly different.
|
study
| 100.0 |
In addition, a regression analysis was implemented on yield data from IR hybrids MON-89Ø34-3 × MON-88Ø17-3 and MON-89Ø34-3 × MON-ØØ6Ø3-6 relative to the conventional control across all studies for which data were available. This analysis included sites that could not be included in the meta-analysis due to fewer than three replicates of data for traits analyzed. The numbers of studies included in the regression analysis were 32 Experimental Phase and 26 Pilot Phase studies.
|
study
| 100.0 |
Field evaluations of MON-89Ø34-3 × MON-88Ø17-3, MON-89Ø34-3 × MON-ØØ6Ø3-6, and MON-ØØ6Ø3-6 were well distributed and representative of each of the five ecoregions during 2009–2013 (Fig. 1). Together, the five ecoregions represent a wide range of conditions: an altitude range of 0–2400 meters above sea level; warm to semi-warm climate, with a mean annual temperature range of 17–26 °C; and subhumid to semiarid and very dry conditions with a mean annual rainfall range of 100–1069 mm (Supplementary Table 1). However, the lack of rainfall in semiarid and very dry environments had no impact on the crop growth because all trials were under irrigation and water was provided as needed (Mendoza et al. 2003), which is a typical practice during the autumn–winter season in these northern regions. Data from each of the 36 studies (Supplementary Table 2) were individually analyzed and a subsequent meta-analysis on the individual results of each trial was carried out. Meta-analysis grouped studies in comparative panels for the two regulatory phases (Experimental and Pilot) across the five ecoregions, multiple sites, and years (2009–2013).
|
study
| 100.0 |
The results of the meta-analysis for the agronomic and phenotypic characteristics for Experimental Phase studies are presented in Fig. 2 (top), and the means and standard errors from individual analyses are presented in Table 1. Agronomic and phenotypic data were collected for 12 different variables across 15 Experimental Phase studies, except that ear height was analyzed in only 11 studies (Table 1). Data were analyzed individually and by meta-analysis to test for differences between the three GM maize hybrids and the conventional control for all variables except dropped ears, which had zero variability, preventing application of a statistical analysis. Thus, a total of 33 statistical tests were conducted between the three GM maize hybrids and the conventional control for 11 variables. No statistical differences were detected for early stand count, days-to-anthesis, days-to-silking, root lodging, stalk lodging, or final stand count for any of the GM hybrids compared to the conventional hybrid control (Table 1, Fig. 2). Furthermore, as noted above, no differences were observed for dropped ears between test and control entries as mean values were numerically low, with zero variability. Statistically significant differences (p ≤ 0.05) between MON-89Ø34-3 × MON-88Ø17-3 and the conventional hybrid control were found for ear height (108.2 vs. 103.3 cm), plant height (210.2 vs. 204.0 cm), grain moisture (18.8 % vs. 18.0 %), and grain yield (10.2 vs. 9.2 t ha−1). Statistically significant differences between MON-89Ø34-3 × MON-ØØ6Ø3-6 and the conventional hybrid control were detected for seedling vigor (7.6 vs. 6.6, on a scale of 1 = poor, 9 = best), plant height (208.2 vs. 201.7 cm), grain moisture (18.5 % vs. 18.1 %), and grain yield (10.0 vs. 9.1 t ha−1). The only statistically significant difference detected between MON-ØØ6Ø3-6 and the conventional control was seedling vigor (7.2 vs. 6.5). For MON-89Ø34-3 × MON-88Ø17-3 and MON-89Ø34-3 × MON-ØØ6Ø3-6 GM maize hybrids, which expressed both insect control (IR) and HT traits, plant height, grain moisture, and grain yield were the three characteristics in common that showed significantly higher values than the conventional hybrid control.Fig. 2Agronomic and phenotypic combined study effect and confidence intervals of MON-89Ø34-3 × MON-88Ø17-3, MON-89Ø34-3 × MON-ØØ6Ø3-6, and MON-ØØ6Ø3-6 GM maize hybrids compared to the conventional control from Experimental Phase (top) and Pilot Phase (bottom) studies. Confidence intervals are shown as standardized differences (differences indicated in standard deviation units) derived from the meta-analysis. Asterisks indicate statistically significant differences between test and control at the 5 % level of significance Table 1Means and standard errors (SE) for phenotypic and agronomic characteristics of MON-89Ø34-3 × MON-88Ø17-3, MON-89Ø34-3 × MON-ØØ6Ø3-6, and MON-ØØ6Ø3-6 GM hybrids and the conventional control for Experimental Phase studies in Mexico during 2009–2013Characteristic (unit)Number of studiesExperimental Phase trialsMON-89Ø34-3 × MON-88Ø17-3MON-89Ø34-3 × MON-ØØ6Ø3-6MON-ØØ6Ø3-6Mean (SE)Mean (SE)Mean (SE)TestControlTestControlTestControlSeedling vigor (1 [poor] to 9 [best])157.0 (0.3)6.7 (0.2)7.6 (0.3)*6.6 (0.3)7.2 (0.2)*6.5 (0.2)Early stand count15199.4 (35.0)202.0 (36.0)194.8 (35.5)202.7 (36.0)200.6 (32.5)202.8 (36.0)Days-to-silking1580.6 (5.4)80.3 (5.3)81.0 (5.4)80.6 (5.3)79.9 (5.2)80.3 (5.3)Days-to-anthesis1578.9 (5.3)78.2 (5.1)78.6 (5.2)78.4 (5.1)77.9 (5.0)78.1 (5.0)Ear height (cm)11108.2 (7.5)*103.3 (7.4)106.9 (8.0)103.1 (7.4)103.9 (7.8)102.3 (7.6)Plant height (cm)15210.2 (6.6)*204.0 (6.5)208.2 (7.5)*201.7 (7.6)204.8 (7.4)202.7 (7.3)Final stand count15109.6 (12.6)103.3 (12.1)108.6 (13.4)102.8 (12.2)103.0 (11.5)103.0 (12.1)Root lodging (%)153.5 (1.7)2.7 (1.1)2.9 (1.1)2.1 (0.8)3.6 (2.0)2.3 (0.8)Stalk lodging (%)152.7 (1.1)4.1 (1.8)3.7 (2.1)4.0 (1.8)4.0 (1.7)4.0 (1.8)Dropped earsa 150.04 (0.03)0.08 (0.07)0.02 (0.02)0.12 (0.07)0.07 (0.05)0.08 (0.07)Grain moisture (%)1518.8 (1.0)*18.0 (0.9)18.5 (1.0)*18.1 (0.9)18.0 (1.0)18.1 (0.9)Grain yield (t ha−1)1510.2 (0.6)*9.2 (0.7)10.0 (0.6)*9.1 (0.8)9.1 (0.8)9.1 (0.8)* Statistically significant at the 5 % level of significance aData on dropped ears were collected but not included in the meta-analysis due to lack of variability
|
study
| 100.0 |
Agronomic and phenotypic combined study effect and confidence intervals of MON-89Ø34-3 × MON-88Ø17-3, MON-89Ø34-3 × MON-ØØ6Ø3-6, and MON-ØØ6Ø3-6 GM maize hybrids compared to the conventional control from Experimental Phase (top) and Pilot Phase (bottom) studies. Confidence intervals are shown as standardized differences (differences indicated in standard deviation units) derived from the meta-analysis. Asterisks indicate statistically significant differences between test and control at the 5 % level of significance
|
study
| 99.94 |
The results of meta-analysis for agronomic and phenotypic characteristics for Pilot Phase trials are presented in Fig. 2 (bottom), and the means and standard errors from individual analyses are presented in Table 2. For comparisons between the three GM maize hybrids and the conventional control, mean values from up to 23 Pilot Phase studies were considered, depending on the evaluated GM hybrid and the observed agronomic/phenotypic characteristics (Table 2). The results of Pilot Phase studies indicated that the three GM maize hybrids were not statistically different from the control for the majority of characteristics evaluated (seedling vigor, early stand count, days-to-silking, days-to-anthesis, plant height, root lodging, stalk lodging, and final stand count; Fig. 2). Statistically significant differences between MON-89Ø34-3 × MON-88Ø17-3 and MON-89Ø34-3 × MON-ØØ6Ø3-6 GM maize hybrids and the conventional control (p ≤ 0.05) were detected for grain yield (8.0 vs. 6.6 t ha−1 and 7.9 vs. 6.5 t ha−1, respectively) and grain moisture (17.8 % vs. 16.8 % and 15.5 % vs. 13.7 %, respectively). The mean values for grain moisture and grain yield were higher for the GM maize hybrids in all comparisons (Table 2). In the Pilot Phase trials, no differences were detected between MON-ØØ6Ø3-6 and the conventional control for any of the characteristics measured.Table 2Means and standard errors (SE) for phenotypic and agronomic characteristics of MON-89Ø34-3 × MON-88Ø17-3, MON-89Ø34-3 × MON-ØØ6Ø3-6, and MON-ØØ6Ø3-6 GM hybrids and the conventional control for Pilot Phase studies in Mexico during 2009–2013Characteristic (unit)Pilot Phase trialsMON-89Ø34-3 × MON-88Ø17-3MON-89Ø34-3 × MON-ØØ6Ø3-6MON-ØØ6Ø3-6Mean (SE)Mean (SE)Mean (SE)Number of studiesTestControlNumber of studiesTestControlNumber of studiesTestControlSeedling vigor (1 [poor] to 9 [best])104.7 (0.7)4.5 (0.8)66.5 (0.6)5.8 (0.9)104.4 (0.7)4.5 (0.8)Early stand count21474.2 (188.3)474.1 (180.7)14490.5 (239.9)535.2 (268.6)20501.2 (193.3)494.4 (188.7)Days-to-silking2381.0 (2.8)80.4 (3.0)1679.0 (3.9)78.1 (4.1)2280.6 (3.2)80.9 (2.9)Days-to-anthesis2379.3 (2.7)78.7 (2.8)1677.5 (3.6)76.6 (3.9)2278.6 (3.0)79.2 (2.7)Ear heighta (cm)360.0 (9.7)60.1 (9.2)361.5 (9.2)60.1 (9.2)363.7 (14.8)64.4 (13.4)Plant height (cm)21191.8 (8.8)189.6 (8.9)14177.1 (11.8)173.3 (12.3)20190.5 (9.2)189.0 (9.2)Final stand count20472.4 (187.0)461.9 (176.4)13451.7 (249.0)487.0 (273.5)19484.3 (196.4)473.2 (185.5)Root lodging (%)173.5 (1.5)4.6 (2.0)115.3 (3.3)6.0 (3.4)163.8 (1.9)4.5 (2.1)Dropped earsa 73.6 (3.2)3.3 (2.7)311.3 (10.0)7.6 (6.1)72.6 (2.3)3.3 (2.7)Stalk lodging (%)191.8 (0.7)2.2 (0.5)131.3 (0.7)1.5 (0.5)181.5 (0.4)2.1 (0.6)Grain moisture (%)1717.8 (1.2)*16.8 (1.1)1115.5 (1.0)*13.7 (0.7)1617.0 (1.1)16.6 (1.2)Grain yield (t ha−1)178.0 (0.7)*6.6 (0.8)117.9 (0.8)*6.5 (1.1)166.4 (0.7)6.3 (0.8)* Statistically significant at the 5 % level of significance aData on dropped ears and ear height were collected but not included in meta-analysis. Data on dropped ears were not included because of lack of variability; data on ear height were not included because of an insufficient number of studies for inclusion
|
study
| 100.0 |
As illustrated in Supplementary Fig. 1, there was a yield advantage in MON-89Ø34-3 × MON-88Ø17-3 and MON-89Ø34-3 × MON-ØØ6Ø3-6 GM maize hybrids relative to the conventional control when analyzed across all studies from both the Experimental and Pilot phases.
|
study
| 100.0 |
The results of the combined study effects analysis for the insect damage measurements are presented in Supplementary Fig. 2, and the means and standard errors from individual analyses are presented in Table 3. Insect damage evaluations were documented in 5–19 Experimental Phase studies of MON-89Ø34-3 × MON-88Ø17-3 and MON-89Ø34-3 × MON-ØØ6Ø3-6 GM hybrids and the isohybrid conventional control (Table 3). The analysis across regions, sites, and years showed statistically significant differences (p ≤ 0.05) between MON-89Ø34-3 × MON-88Ø17-3 and the conventional control for Diabrotica root damage (0.05 vs. 0.11 rating), corn earworm damage (0.46 vs. 2.40 cm2), and Spodoptera leaf damage (0.20 vs. 1.94 rating) (Table 3 and Supplementary Fig. 2). MON-89Ø34-3 × MON-ØØ6Ø3-6 had statistically significant differences from the conventional control for corn earworm damage (0.31 vs. 1.87 cm2) and Spodoptera leaf damage (0.33 vs. 2.23 rating) (Table 3). As expected, in all cases of significant differences, the level of insect damage was greater for the conventional control using regional best practices for insect pest control than for the GM IR maize hybrids.Table 3Means and standard errors (SE) for insect damage characteristics of MON-89Ø34-3 × MON-88Ø17-3 and MON-89Ø34-3 × MON-ØØ6Ø3-6 GM hybrids and the conventional control in Experimental and Pilot Phase studies in Mexico during 2009–2013Characteristic evaluated (unit)Study typeMON-89Ø34-3 × MON-88Ø17-3MON-89Ø34-3 × MON-ØØ6Ø3-6No. of studiesMean (SE)No. of studiesMean (SE)TestControlTestControlStalk borer (Diatraea spp.) tunnel length (cm)Experimental140.01 (0.01)1.09 (0.57)110.25 (0.24)0.55 (0.31)Pilot240.02 (0.01)0.18 (0.07)*110.00 (0.00)0.17 (0.08)Stalk borer (Diatraea spp.) tunnel numberExperimental160.00 (0.00)0.16 (0.06)120.01 (0.01)0.05 (0.01)Pilot170.00 (0.00)0.04 (0.01)*40.01 (0.01)0.10 (0.07) Diabrotica root damage (0–3 scale)Experimental180.05 (0.01)0.11 (0.02)*50.13 (0.06)0.12 (0.05)Pilot260.01 (0.00)0.02 (0.01)*130.07 (0.04)0.06 (0.04)Corn earworm (Helicoverpa zea or Spodoptera spp.) damage (cm2)Experimental190.46 (0.18)2.40 (0.51)*150.31 (0.10)1.87 (0.48)*Pilot260.19 (0.10)2.08 (0.31)*130.11 (0.05)1.91 (0.37)* Spodoptera leaf damage (0–9 scale)Experimental190.20 (0.09)1.94 (0.34)*150.33 (0.14)2.23 (0.41)*Pilot160.06 (0.03)1.49 (0.35)*130.05 (0.03)1.26 (0.41)Cutworma (Agrotis or Spodoptera spp.) damage (number of seedlings)Experimental––––––Pilot30 (0.00)35.88 (25.45)*30 (0.00)37.11 (24.07)**Statistically significant at the 5 % level of significance aCutworm (Agrotis spp.) was not present in Experimental Phase trials, and was not included in meta-analysis for Pilot Phase trials because of the small number of studies
|
study
| 100.0 |
Insect damage evaluations were performed in 3–26 Pilot Phase studies on the two GM IR hybrids and the conventional control (Table 3, Supplementary Fig. 2). Results from the comparative analysis between the GM hybrid MON-89Ø34-3 × MON-88Ø17-3 and the conventional control showed statistically significant differences (p ≤ 0.05) for stalk borer tunnel length (0.02 vs. 0.18 cm), stalk borer tunnel number (0.00 vs. 0.04), Diabrotica root damage (0.01 vs. 0.02 rating), corn earworm damage (0.19 vs. 2.08 cm2), Spodoptera leaf damage (0.06 vs. 1.49 rating) and cutworm (Agrotis and/or Spodoptera spp.) damage (0.00 vs. 35.88 seedlings) (Table 3, Supplementary Fig. 2). MON-89Ø34-3 × MON-ØØ6Ø3-6 showed statistically significant differences (p ≤ 0.05) for corn earworm damage (0.11 vs. 1.91 cm2) and cutworm (Agrotis and/or Spodoptera spp.) damage (0.00 vs. 37.11 seedlings) (Table 3).
|
study
| 100.0 |
Weed populations present in the three GM maize hybrids and the conventional isohybrid control were documented in Experimental Phase (2010–2012) and Pilot Phase (2012–2013) studies. The weed inventories included species adapted to the different regions and are typical of agricultural fields (Agundis Mata and Concepción Rodríguez 1978; Rosales Robles and Sánchez de la Cruz 2010). Only those weeds of agronomic importance are reported here. Twenty-five different weed species were documented in the Experimental Phase studies; the five most common species of agronomic interest were Amaranthus palmeri, Chenopodium album, Convolvulus arvensis, Echinochloa colona, and Portulaca oleracea. In the Pilot Phase studies, 48 different weed species were documented; the 13 species of most agronomic importance were Amaranthus palmeri, Chamaesyce maculate, Chenopodium spp., Convolvulus arvensis, Cyperus esculentus, Echinochloa colona, Helianthus annuus, Leptochloa filiformis, Malva parviflora, Physalis spp., Portulaca oleracea, Solanum elaeagnifolium, and Sorghum halepense. Overall, Sinaloa, Tamaulipas, and Comarca Lagunera showed the highest numbers of species, with 30, 20, and 13 different weed species, respectively.
|
study
| 99.94 |
Weed control evaluations were available from 4 to 8 Experimental Phase studies and from 9 to 16 Pilot Phase studies (Table 4) but were not subject to meta-analysis. Evaluations of weed control efficacy by glyphosate applications in the three GM hybrids and by mechanical treatment in the conventional isohybrid were conducted at 11, 20, and 30 days after treatment. Weed control in the GM hybrids with up to two over-the-top complete applications of Faena Fuerte® with Transorb® was consistently higher than for the alternative weed control treatment in the isohybrid control. On average, weed control in the GM hybrids was 3.1 % higher than in the isohybrid conventional control in the Experimental Phase studies, and 13.1 % higher than the control in the Pilot Phase studies (Table 4).Table 4Weed control means in Experimental and Pilot Phase studies of MON-89Ø34-3 × MON-88Ø17-3, MON-89Ø34-3 × MON-ØØ6Ø3-6, and MON-ØØ6Ø3-6 GM hybrids and the conventional isohybrid control in Mexico 2010–2013a HybridAverage no. of days after treatmentExperimentalPilotNo. of studies% weed controlNo. of studies% weed controlTestControlTestControlMON-89Ø34-3 × MON-88Ø17-31190.983.389.865.420895.995.21692.877.93098.691.195.185.5Average95.189.992.576.3MON-89Ø34-3 × MON-ØØ6Ø3-61188.484.889.882.720897.599.7995.686.43099.3100.096.789.7Average95.094.994.086.3MON-ØØ6Ø3-61188.283.391.272.820496.895.21594.977.93095.691.195.585.4Average93.589.993.978.7 aWeed control data were not subject to meta-analysis
|
study
| 100.0 |
Maize is the most important staple crop in Mexico, where a variety of maize types and production systems are present. Currently, in-country maize production is not sufficient to meet internal demand (Turrent Fernández et al. 2012; Blanco et al. 2014). Maize production is highly technified in Northern Mexico, and yield potentials are similar to those observed in the US Corn Belt (Turrent Fernández et al. 2012). Higher yields in Northern Mexico are associated with the use of improved conventional maize hybrids, irrigation, fertilizers, and appropriate crop management (e.g., weed and insect control). The use of pesticides in Mexico is the highest (4.5 kg ha−1) in North America (Stokstad 2013). Recent reports have documented the need and potential benefits of adopting IPM programs and newer, more sustainable technologies in corn production in Mexico (Bell et al. 2012; Blanco et al. 2014). IPM programs would minimize economic losses and would lower environmental and health risks. Once approved, GM maize potentially offers an additional tool for Mexican farmers for insect and/or weed control, increasing yields while reducing the number of insecticide applications.
|
review
| 98.75 |
The Mexican Biosafety Bylaw provides an operational guide for the preparation, review, and approval of GM crops in Mexico (DOF 2008). Current regulations require developers to present an ERA along with submission of experimental field trial applications. Apart from biosafety measures and administrative requirements, planting permits impose mandatory field protocols to generate in-country data to test for potential changes in GM crops that may be harmful to the environment, the plant, or animal health. These protocols have been conducted to advance the introduction of GM traits in maize cultivation systems in Northern Mexico. An ERA and the information generated from field studies of GM maize hybrids together enable regulators and agricultural policy makers to make informed decisions on the legal use and responsible adoption of GM crops in Mexico. Field studies with GM plant materials are conducted under robust and extensive biosafety protocols adopted by technology developers (industry and academic scientists) to ensure best management practices and extended life for GM crops (ETS 2015). In addition, studies comparing GM hybrids and controls in the same hybrid background provide a very powerful tool to minimize sources of variability and allow appropriate comparisons in order to best assess the potential environmental risks of introgressed GM traits.
|
review
| 99.75 |
Meta-analysis of agronomic and phenotypic characteristics from up to 15 Experimental Phase studies (33 statistical tests; Table 1) confirmed that MON-89Ø34-3 × MON-88Ø17-3, MON-89Ø34-3 × MON-ØØ6Ø3-6, and MON-ØØ6Ø3-6 GM maize hybrids were no different from the conventional hybrid control for early stand count, days-to-anthesis, days-to-silking, root lodging, stalk lodging, and final stand count, so phenotypic characteristics that define crop establishment (e.g., early stand count) were similar in both test and control materials (Fig. 2, top). Also, the absence of differences in the time to reach flowering (anthesis and silking) indicates that plant growth and development were similar between test and control materials and responded in a similar manner to growing conditions (temperature, soil moisture, nutrients, etc.) and crop management. In contrast, differences in grain yield between MON-89Ø34-3 × MON-88Ø17-3 and MON-89Ø34-3 × MON-ØØ6Ø3-6 GM maize hybrids and the conventional hybrid control (Fig. 2) could be a result of less damage induced by target insect lepidopteran pests (Spodoptera spp.), better plant health, and overall less stressful conditions for the GM hybrids, enabling them to reach more of their full yield potential.
|
study
| 100.0 |
Similarly, analysis from up to 23 Pilot Phase studies (Table 2) indicated that the three GM maize hybrids were not statistically different from the control for seedling vigor, early stand count, days-to-silking, days-to-anthesis, plant height, root lodging, stalk lodging, or final stand count (Fig. 2, bottom), confirming agronomic equivalence in key phenotypic and agronomic characteristics. Statistically significant differences between MON-89Ø34-3 × MON-88Ø17-3 and MON-89Ø34-3 × MON-ØØ6Ø3-6 GM maize hybrids and the conventional control (p ≤ 0.05) were detected for grain yield and grain moisture (Table 2). Higher grain moisture at harvest and higher grain yield were likely due to overall better plant health throughout the crop season, as a result of protection from target insect pests and better weed control through use of broad-spectrum herbicide applications. Regression analyses of these two hybrids indicated that in most cases they had greater yield than the conventional control hybrids across the Experimental and Pilot Phase studies (Supplementary Fig. 1). Furthermore, according to this analysis, growers would benefit from the use of IR/HT GM hybrids under conditions with relatively low yield potential. The average difference of 1.18 t ha−1 between GM IR maize hybrids and the conventional (non-GM) control, which was obtained using best regional management practices across the Experimental and Pilot studies, could represent a substantial increase in maize production in the northern states of Mexico.
|
study
| 99.94 |
Increased pest potential for a GM crop plant could include increased weediness in a cultivated field or increased invasiveness in natural vegetation. For a corn plant to become more weedy or invasive it would likely need seed dormancy and seed dispersal mechanisms to secure survival in new areas. No differences were detected in early stand count (Tables 1 and 2) or in laboratory seed germination tests, which showed >94 % germination in each of the hybrids (data not shown), thus indicating no changes in seed dormancy. Furthermore, no differences were observed for dropped ears (which would facilitate seed dispersal) between test and control entries, providing additional evidence that the GM traits have not increased weediness (Tables 1 and 2).
|
study
| 100.0 |
When the above results are considered in the context of an ERA and familiarity with the maize crop, none of the characteristics where statistically significant differences were found are considered to increase pest potential or any other potential risk to the receiving environment, plant health, or animal health.
|
other
| 99.75 |
Many studies have documented the economic benefits to growers from the adoption of GM crops (Finger et al. 2011; Brookes and Barfoot 2015). Specifically, benefits included production cost savings (fewer pesticide applications), higher yields due to crop protection against targeted lepidopteran and coleopteran insect pests, and an overall improvement in the economics of farming households that have adopted GM crops (Finger et al. 2011; Lee et al. 2012; Areal et al. 2013; James 2014; Klümper and Qaim 2014). Relative increases in yield and profits from cultivating GM crops have been shown to be higher in developing countries than in developed countries (Finger et al. 2011; James 2014; Klümper and Qaim 2014). In Argentina, the benefit to farmers derived from adoption of GM IR maize hybrids was a net increase in yields of about 5 %, achieved by preventing losses caused by Diatraea saccharalis (stalk borer) and Spodoptera frugiperda (fall armyworm), and was estimated at US$170 M for the period 1998–2003 (Trigo 2011). The economic benefit in terms of cost reduction was US$20 ha−1 when using maize hybrids with stacked traits for IR and HT (Trigo 2011). Most of the cost reduction was likely due to decreases in insect control costs, with some additional savings due to reduced weed control costs. Other studies have confirmed such benefits (Qaim 2009; Solleiro Rebolledo and Castañón Ibarra 2013).
|
review
| 99.5 |
The threshold level (5 % plants damaged) to trigger lepidopteran pest control applications was never reached for the MON-89Ø34-3 × MON-88Ø17-3 and MON-89Ø34-3 × MON-ØØ6Ø3-6 GM maize hybrids in any study. This was expected given the intrinsic lepidopteran and coleopteran IR traits in these two hybrids conferred by the expression of Bt-derived proteins in the plant. As expected, no differences were detected between MON-ØØ6Ø3-6 and the conventional isohybrid maize for insect damage since neither plant material contains IR traits; both were affected equally by lepidopteran or coleopteran insect pests and both received chemical insect-control applications in these trials. Consequently, the threshold level (5 % plants damaged) to apply an insect-control treatment was reached once or twice during the growing season for MON-ØØ6Ø3-6 and the conventional isohybrid controls. These observations are consistent with those by Finger et al. (2011), Areal et al. (2013), and Blanco et al. (2014), thus confirming that GM IR and HT maize hybrids could be utilized as a beneficial alternative tool in IPM programs in Mexico. The reduction in use of additional insecticide applications to control lepidopteran pests such as fall armyworm (Spodoptera spp.) would help reduce the amount of insecticide active ingredients used per year in Mexico and would result in production cost savings for growers. In addition, use of GM IR hybrids may provide benefits associated with the reduction of pesticide loads in the environment.
|
study
| 99.94 |
These desirable outcomes from adopting GM IR crops have already been achieved by GM cotton growers in Mexico (Traxler and Godoy-Avila 2004) and maintained over the last 18 years (Brookes and Barfoot 2015). Genetically modified IR cotton varieties have resulted in more than 50 % reduction in pesticide use and have doubled the annual net revenue per hectare compared to that of growers cultivating conventional varieties in the Comarca Lagunera region (Traxler and Godoy-Avila 2004).
|
other
| 99.75 |
A popular agronomic practice in GM crop production systems in Argentina and the USA is reduced tillage (Trigo 2011; Lee et al. 2012). In Argentina, reduced tillage has made it possible to reverse the negative consequences related to extensive use of arable land and has allowed a more efficient energy use balance for crop production (Trigo 2011). In this context, the use of GM maize hybrids tolerant to the herbicide glyphosate has simplified weed control and/or reduced the costs involved (Norsworthy and Frederick 2005). Furthermore, implementation of reduced tillage practices may provide additional benefits including improved soil fertility, reduced erosion, increased carbon sequestration, and the use of herbicides with better environmental profiles (Trigo 2011). Similar results were observed in the present studies, where the three GM maize hybrids enabled over-the-top applications of Faena Fuerte® with Transorb® and provided better and more cost-effective weed control than the conventional control hybrids.
|
study
| 99.94 |
The agroecological characteristics of the level IV ecoregions where the studies were conducted represented a diverse range of environments suitable for agricultural utilization (Supplementary Tables 1 and 2). The main soil textures found across locations were clay, silty clay, clay loam, sandy loam, sandy clay loam, and sandy silt, with climates ranging from semi-warm (e.g., ecoregion 10.2.4.1, Chihuahua and Comarca Lagunera, with annual temperatures of 17–20 °C), to warm (e.g., ecoregion 14.3.1.2, Sinaloa, with annual temperatures of 22–26 °C). Rainfall was more variable, but most ecoregions received less than 200 mm with the exception of ecoregion 9.5.1.2 (Tamaulipas), with annual rainfall of 1069 mm. Likewise, the altitude was less than 400 m above sea level for most of the regions. However, ecoregion 10.2.4.1 (Chihuahua) had an altitude that ranged from 1000 to 2400 m above sea level. As previously mentioned, however, even geographically distinct ecoregions show homogeneity in factors such climate, soils, and water availability that define geographic zones within these ecoregions that are well suited for agricultural production and are used for this purpose. The similarity in agroclimatic characteristics of the agricultural sites where CFTs were implemented (Supplementary Table 1), in addition to the consistent results observed across all 36 studies through the use of standardized protocols, measurement endpoints, and data recording methods (Tables 1, 2, 3, 4), supports transportability of characterization data and assessments among ecoregions for ERA purposes. Overall, results from these ERA studies are consistent with other studies previously done in other world regions (US EPA 2008; James 2014). Furthermore, additional results of field studies obtained from multiple geographies for GM soybean (Horak et al. 2015) and GM maize (Nakai et al. 2015; Ahmad et al. 2016) demonstrate the utility of relevant data transportable across regions for the ERA of GM crops.
|
study
| 62.0 |
The Mexican regulatory framework requires an ERA to be submitted with each application for a CFT of a GM crop product and requires the implementation of plant characterization studies to test risk hypotheses on a case-by-case approach. To improve efficiency in the field testing efforts, representative and strategic field locations with similar agroecological characteristics across ecoregions are recommended to obtain results that would be transportable from one ecoregion to another (Garcia-Alonso et al. 2014). In general, application of data transportability conceptual models and procedures could increase the efficiency and power of field testing programs while reducing regulatory workload and costs. In the case of GM maize, ERAs done in Uruguay (CAI 2011, 2012) and Argentina (CONABIA, unpublished data) concluded that the risk of production and use of IR/HT GM maize for food and feed was not different from that of the conventional counterpart. In Argentina, this conclusion was based on data from plant characterization studies executed in US locations with very similar agroecological conditions to maize production regions in Argentina; therefore, the conclusions obtained from the US studies were transportable to the local agroecosystems (Monsanto Company internal communication). These approaches should be extended in the future.
|
study
| 87.94 |
The regulatory framework in Mexico enabled field characterization of GM maize hybrids resistant to lepidopteran and/or coleopteran insects and tolerant to glyphosate herbicide in multiple locations of Northern Mexico in order to inform the ERA. The agronomic and phenotypic characteristics measured in 36 studies conducted across agricultural regions during 2009–2013 demonstrated that MON-89Ø34-3 × MON-88Ø17-3, MON-89Ø34-3 × MON-ØØ6Ø3-6, and MON-ØØ6Ø3-6 GM maize hybrids were not different from conventional maize hybrids in potential risks of weediness, pest potential, competition, or displacement. Thus, it was demonstrated that introgression of GM traits into the maize crop did not cause unexpected modifications to the plant or changes in the crop that would suggest changes in pest potential. Together, these results and crop management considerations to reduce gene flow (Baltazar et al. 2015) strongly support the conclusion that commercial plantings of GM maize hybrids would not increase potential environmental risks for cultivation and conservation of maize in Mexico. Furthermore, the results from these studies indicate that MON-89Ø34-3 × MON-88Ø17-3, MON-89Ø34-3 × MON-ØØ6Ø3-6, and MON-ØØ6Ø3-6 GM hybrids are valuable options for integrated crop production systems that can increase productivity per unit area, provide economic gains to Mexican farmers through reduction of production costs for pest control (insects and/or weeds), and benefit the environment.
|
study
| 99.7 |
The clinical burden of peripheral arterial events is substantial, with high case fatality, poor functional outcome, and a high rate of emergency and subsequent vascular intervention to prevent death and limb loss . We present a case of left upper extremity paresis secondary to acute brachial artery occlusion in an elderly female with active non-ST segment elevation myocardial ischemia (NSTEMI) in the setting of paroxysmal atrial fibrillation. The patient was initially suspected to have a cerebrovascular attack (CVA); however, computed tomography (CT) head was negative for acute stroke. The presence of skin mottling, coolness of the arm, pallor, decreased sensation, and pulseless led to a further investigation with a computed tomographic angiography (CTA) of the upper extremity, confirming the diagnosis of acute left brachial artery occlusion. Acute limb ischemia should be considered in the differential diagnosis of acute stroke with atypical presentation.
|
clinical case
| 99.94 |
The patient is an 83-year-old female who presented to an outside rural hospital emergency department with a complaint of nausea and chest discomfort of one-day duration. Her medical history included hypertension, hyperlipidemia, carotid artery stenosis, traumatic subarachnoid hemorrhage, transient ischemic attack, and paroxysmal atrial fibrillation. She is a nonsmoker. On exam, she was normocardic with a regular rhythm. The rest of her vital signs were normal. Laboratory investigation revealed white blood cell count 6.9 K/uL, hemoglobin 14.6 g/dL, platelet count 170 K/uL, lipase 21, and an abnormal troponin level 0.180 ng/mL. An electrocardiogram (ECG) obtained reveal normal sinus rhythm, pulse rate 60. The emergency department physician diagnosed non-ST elevation myocardial ischemia (NSTEMI). Her chest discomfort improved with administration of nitroglycerin and morphine; anticoagulation with heparin drip was initiated and she was transferred to our facility. Her home medications include baby aspirin, metoprolol, and ramipril.
|
clinical case
| 100.0 |
On arrival, she complained of acute onset left upper extremity weakness. A stroke alert was initiated. The patient’s systolic blood pressure was 180 mmHg and the ECG demonstrated atrial fibrillation at 90 beats per minute. On neurologic examination, the left upper extremity strength revealed no effort against gravity with some preserved strength in wrist and finger extension. Diminished sensation to gross touch on the left forearm compared to the right. Findings from the remainder of the neurological examination, including speech and language, cranial nerves, coordination, and left lower extremity strength and sensation, were normal. A computed tomography scan of the brain showed no gross evidence of intracranial hemorrhage. There was hypodensity representing age-indeterminate infarct within the left occipital lobe and age-indeterminate periventricular and subcortical small vessel ischemic changes.
|
clinical case
| 100.0 |
Given that weakness and mottling were prominent, palpation of the left upper extremity for pulses was done. The left brachial, radial, and ulnar pulses were not palpable, and the left upper extremity was colder than the right upper extremity. There were also no appreciable Doppler signals. A CTA of the left upper extremity was performed, which revealed left distal brachial artery occlusion (Figure 1). Vascular surgery was consulted. Intravenous heparin drip was resumed and the patient was sent to the operating room for emergent left upper extremity exploration and embolectomy of the left brachial artery.
|
clinical case
| 99.94 |
Postoperatively, a transthoracic echocardiogram obtained was negative for an intracardiac thrombus. The patient recovered well (normal left arm strength and range of motion and intact sensation to gross touch) and was discharged home on postoperative Day 5 on aspirin and coumadin with a goal international normalization ratio (INR) of two to three.
|
clinical case
| 99.94 |
The clinical burden of peripheral arterial events is substantial, with high case fatality, poor functional outcome, and a high rate of emergency and subsequent vascular intervention to prevent death and limb loss . We present a case of left upper extremity paresis secondary to acute brachial artery occlusion in a patient with active NSTEMI in the setting of paroxysmal atrial fibrillation. The patient was initially suspected to have a cerebrovascular attack (CVA); however, the CT head was negative for acute stroke. The presence of skin mottling, coolness of the arm, pallor, decreased sensation, and pulseless led to a further investigation with CTA of the upper extremity, confirming the diagnosis of acute left brachial artery occlusion.
|
clinical case
| 99.94 |
Vascular disease is the leading cause of death and disability worldwide . Acute limb ischemia (ALI) is the sudden decrease in limb perfusion, usually producing new or worsening symptoms and signs, and often threatening to limb . ALI is considered a vascular emergency . The incidence of ALI is 10 to 14 per 100000 per year . The incidence of peripheral arterial events is similar between men and women, although women tend to have events at an older age . The risks factors for atherosclerosis (hypertension, male sex, smoking, diabetes mellitus, and hyperlipidemia) are present in about 39.8% of patients with ALI. Previous atrial fibrillation was common in patients with ALI with a prevalence of 38.7% . The most prevalent cause of ALI events was embolism 46.2% .
|
review
| 99.9 |
Patients with upper extremity ALI are more likely to have atrial fibrillation (50%) as compared to the 29.8% of patients with lower extremity acute limb ischemia , while patients with lower extremity ALI had a higher percentage of aortic or mitral valvular disease or intracardiac thrombus . Upper extremity emboli are more frequent in women and patients with atrial fibrillation. Lower extremity emboli are more frequent in the presence of valvular disease or intracardiac thrombus and are associated with increased 30-day limb loss and mortality .
|
other
| 93.7 |
Upper extremity arterial occlusions can have a variety of presenting factors. Two of the most commonly described features are coldness and pain in the affected extremity, often occurring distally first and moving proximally. The pain is often a rest pain in acute occlusion but could also be claudication. Other presenting findings include paresthesia, paralysis, cyanosis, or pallor, decreased or absent radial or ulnar pulse, and gangrene of the digits . If any of these symptoms are present, it is important to consider an arterial occlusion of the upper extremity. The patient will often also have predisposing conditions to thrombus formation and subsequent embolization. These conditions include myocardial infarction, atrial fibrillation, valvular heart disease, and other less common cardiac and noncardiac causes of emboli .
|
other
| 97.1 |
Clinical evaluation of patients with suspected arterial occlusion will demonstrate a change in temperature (coolness to touch) along the extremity affected as compared to the unaffected extremity. Furthermore, the bilateral pulse exam will demonstrate a diminished or absent palpable or Dopplerable pulse distal to the site of occlusion in the affected extremity. A CTA can be used to confirm the occlusion, while an urgent vascular surgery or an interventional radiology consult is necessary .
|
other
| 99.9 |
The three main treatments for acute limb ischemia include open surgical revascularization, endovascular revascularization, and anticoagulation with observation. Fluid resuscitation, pain control, and unfractionated heparin can be utilized to temporize the patient until definitive management can occur . In patients presenting with ALI, the endovascular therapy and surgical revascularization approaches have similar rates of short-term and 12-month mortality, limb amputation, and recurrent ischemia .
|
review
| 99.7 |
In evaluating a patient with concern for acute stroke with atypical presentation, it is essential to obtain a complete history and perform a rapid and thorough examination. Acute limb ischemia should be considered in the differential diagnosis of CVA with atypical presentation.
|
other
| 99.9 |
Parasites are thought to adversely affect the physical performance of their hosts and to be key factors in shaping life history, with effects cascading to communities and ecosystems . Haemosporidian parasites, the causative agents of malaria in the broader sense, commonly occur in temperate and tropical regions and infect a variety of host species including humans, other mammals, reptiles and birds. Depending on lineage and host species, the parasites invade their hosts' inner organs and, particularly, red blood cells . The infection follows a typical pattern with an acute (symptomatic) phase with high levels of parasites in the blood (parasitaemia) followed by a chronic phase with low (or zero) parasitaemia . Malaria in wildlife is often a mild disease, but can have severe consequences, particularly when encountered in new environments by immunologically naive hosts . Acute infections (with high parasitaemia) can result in substantial declines in red blood cell content owing to haemosporidians targeting haemoglobin as a major nutrient .
|
review
| 96.0 |
Given the very high rates of oxygen delivery required by birds to sustain the aerobic demands for flapping flight, it is somewhat perplexing that even successful long-distance migrants commonly display chronic malaria infections . Although parasitaemia in chronically infected birds is substantially lower than during a primary infection , the consequences of low parasitaemia on the aerobic metabolism of birds have not been examined. Measuring the aerobic metabolism can provide important insights into two potential effects of chronic parasitaemia: the energetic cost of a persistent infection through measurements of resting metabolic rate (RMR) and its consequences on the aerobic performance of the infected individual through measurements of maximum metabolic rate (MMR) .
|
study
| 100.0 |
Endothermic animals have a basal, or minimal, rate of metabolism (basal metabolic rate; BMR) when they are post-absorptive, asleep in the rest-phase of their daily cycle, exposed to thermoneutral temperatures, and not engaged in energetically demanding life-history stages. Thus, the BMR represents an individual's baseline costs of maintaining vital functions . Metabolic measurements made under the same conditions but at times associated with elevated maintenance costs, such as during moult, during the day, or at temperatures outside the thermoneutral zone are termed RMR. Thus, BMR and RMR are pertinent reflections of the energetic costs of physiological processes at particular life-history stages and, thus, can be used to quantify the contemporaneous energy costs of parasite infections. Surprisingly, studies examining the effects of endoparasitic or ectoparasitic infection on host RMR are inconsistent, finding lower, higher or unchanged RMR owing to parasitic infections (reviewed in ). However, even if infections have minimal effect on an animal's maintenance metabolism, they could still limit their host's capacity for intense aerobic activities . Reduced aerobic capacity would be especially deleterious for long-distance flyers, as such flight requires sustained delivery and uptake of oxygen at high rates .
|
review
| 99.9 |
The potential for parasite infections to affect aerobic capacity can be determined by measuring the MMR. The highest rates of aerobic metabolism in endotherms are associated with sustainable exercise ; consequently, MMR can only be measured when animals attain peak levels of locomotor activities. In addition, because MMR depends on the integrated performance of body functions ranging from enzymes to organ systems , its measurement may provide insight into an animal's overall physiological vigour.
|
study
| 99.94 |
We have examined the metabolic consequences of blood parasite infections over three consecutive stages of the annual cycle in great reed warblers (Acrocephalus arundinaceus), which are long-distance Palaearctic migrants with non-breeding sites in tropical Africa . We expect a haemosporidian infection will decrease a host's aerobic capacity, and, in turn, reduce both its MMR and its exercise endurance. Moreover, we expect that adverse effects of parasite infection to be particularly apparent during the migration stage, with its associated requirement for high aerobic capacity.
|
study
| 100.0 |
To this end, we measured RMR and MMR in infected and uninfected birds from late breeding until early migration. Specifically, we employed a two-tiered approach: (i) we experimentally inoculated captive, previously uninfected individuals with a parasite strain selected for low virulence and monitored the developing infections along with repeated measures of aerobic performance for comparison with that of uninfected controls; and (ii) we undertook the same physiological appraisal of freshly captured birds, knowing they were likely to have a higher variety of infections with naturally occurring haemosporidian parasites and a greater range of parasitaemia than our captive birds. As an additional performance measure, we recorded the duration of sustained intense exercise during individual MMR measurements.
|
study
| 100.0 |
The study was carried out on a population of great reed warblers (A. arundinaceus) breeding in the Danube River floodplains near Kalimok Biological station (44°00′ N, 26°26′ E, Bulgaria). This population is naturally infected with haemosporidian parasites with a prevalence of approximately 27–40% [17–19].
|
study
| 99.94 |
Great reed warblers were caught in reed beds using mist nets from April to August 2015. Birds were measured (body mass and wing length), aged, ringed and sexed. Additionally, we sampled approx. 30–50 µl blood from a brachial vein for blood smears, measured haemoglobin content (mg ml–1) using a HemoCue Hb201, and the remainder was stored in 0.5–1 ml SET-buffer (0.15 M NaCl, 0.01 M Tris, 0.001 M EDTA, pH 8.0) for subsequent genetic analyses of parasite types.
|
study
| 99.94 |
We analysed the Giemsa stained blood smears by microscopy to quantify parasitaemia as the proportion of infected red blood cells (%). This was determined by counting infected erythrocytes in 100 randomly selected microscopic fields under 1000 magnification and by relating the number of infected to the total number of erythrocytes per microscopic field, determined from five pictures taken every 20 fields (mean number of erythrocytes per microscopic field: 306 ± 69 (s.d.), n = 550).
|
study
| 100.0 |
For the genetic analyses, we extracted total DNA from blood samples and tested for Plasmodium and Haemoproteus infections by nested PCR protocol for mitochondrial cyt b . Positive samples were sequenced by Macrogen Inc. (http://www.macrogen.com) to discriminate between Plasmodium and Haemoproteus.
|
study
| 100.0 |
We quantified oxygen consumption rates during overnight rest (RMR), and during forced exercise (MMR) using flow-through respirometry. The aerobic performance was measured from July until the end of August, which includes late-breeding, post-breeding and the initial autumn migration periods of great reed warblers . Because birds had just completed breeding or were in pre-migratory or migratory stages, the strict conditions of measuring BMR might not be fully met and, thus, we consider overnight oxygen consumption rates to represent RMRs .
|
study
| 99.94 |
We defined RMR (V̇O2) as the lowest oxygen consumption rate over a 5 min period during nocturnal rest under thermoneutral conditions (30°C) and in a post-absorptive state. For measurements, birds were placed in individual respirometry chambers (4 l volume; for details see ). Measurements started around 21.00 h and lasted until the following morning at 06.00 h. Oxygen consumption rate (ml min–1) was determined from differences between inlet and outlet O2 concentrations by an Oxzilla II Differential Oxygen Analyzer (Sable Systems, NV, USA). Gas flow rate was regulated at 500 ml min–1 using calibrated mass-flow metres (Tylan Corp.) and all oxygen measurements were baselined using reference air at 30-min intervals. Data were analysed using LabAnalyst software (http://warthog.ucr.edu).
|
study
| 100.0 |
MMR (V̇O2 max) were determined from oxygen consumption during exercise in a hop-flutter wheel, where birds were encouraged to repeatedly take off . The effective volume of the MMR system was 36.0 l, with air supplied at a rate of 7.5 l min−1 using a calibrated mass-flow controller (MKS Instruments). The rotation speed of the wheel was manually adjusted to each bird's behaviour and fully stopped when the bird could not hold its position in the wheel (which was recorded as time until exhaustion, min). Oxygen consumption during exercise was continuously recorded with an Oxzilla II differential oxygen analyser or an FC1 oxygen analyser (all Sable Systems, NV, USA), using inlet air as a reference at the start and end of each measurement. The maximum VO2 was computed from the highest instantaneous oxygen consumption values measured over a 30 s interval of exercise, after baseline correction and smoothing the data to remove electrical noise (1 s smoothing interval over three cycles). All data were processed using LabHelper and LabAnalyst (http://warthog.ucr.edu) software to obtain oxygen consumption rates.
|
study
| 100.0 |
Prior to the actual infection experiment, we needed to select a specific parasite strain for experimental infection and constitute donors for both experimental and control groups. We chose Plasmodium relictum cyt b lineage pGRW04, which naturally occurs in our study species . From catches of wild birds in spring 2015, we selected one individual with a natural pGRW04 infection and five non-infected individuals. All birds were kept indoors in isolated vector-proof cages (100 × 60 × 45 cm) supplied with water and food ad libitum (living mealworms plus a mix of boiled eggs and commercial dry food for insectivorous birds (www.versele-laga.com). The pGRW04 infection was multiplied in four recipient birds by sub-inoculating infected blood into the pectoral muscle. We injected approximately 250 µl of a blood mixture (infected blood, 3.7% sodium citrate solution and 0.9% sodium chloride solution in a 4:1:1 mixture) into each recipient's breast muscle within 5 min after blood withdrawal. One non-infected individual was spared and used as a donor for the control group (see below).
|
study
| 100.0 |
For the infection experiment, we caught wild birds at the end of the breeding season in June and July and selected adult males to minimize variation owing to sex or age. All individuals were evaluated for infection, with those testing negative quarantined for at least one week before confirming infection status. These birds were then kept in vector-protected aviaries furnished with cut reeds, several feeders and water ad libitum. The aviaries allowed free ranging between an indoor (1.3–2.6 × 2.3 × 2.5 m) and an outdoor section (size: 1.5–2.5 × 1.1 × 2.4 m).
|
study
| 99.94 |
Thirty-two individuals entered the experiment and were randomly assigned to either a ‘control’ or ‘experimental’ group. The 16 experimental individuals received blood from the infected donor group and the 16 controls received blood from a non-infected donor, following the above procedure. The experimental protocol generally followed .
|
study
| 99.94 |
Starting 5 days after experimental or control inoculation, we determined infection status of each bird from microscopic examination of blood smears collected at 3 day intervals for at least 25 more days or when parasitaemia had dropped to a chronic level (median: 0.0015%).
|
study
| 99.94 |
In addition to the infection experiment, we examined 124 free-living great reed warblers (95 males, 12 females and 17 birds of unknown sex) over late-breeding (July 2015), post-breeding (late July/early August) and migration periods (late August). In addition to standard biometric measurements of body mass, fat score, pectoral muscle score and wing size , we determined each bird's infection status and parasitaemia by PCR and microscopy. The total haemosporidian prevalence in the sample for the seasonal effect measurement was 45.2% with Plasmodium ssp. infections accounting for 13.0%, Haemoproteus ssp. for 29.9% and mixed infections for 2.6%. In nine birds, the PCR signal was positive yet no infected cells were found by microscopy. Therefore, parasitaemia must have been lower than one infected cell in 100 microscopic fields (less than 0.003%) and we set it to 0.0015%, i.e. half of the value at microscopic detection limit. Finally, for the later analyses, we categorized birds according to their parasitaemia with zero, low (less than 0.2%) and high parasitaemia (greater than 0.2 to max. 4.0%). The ‘high-parasitaemia’ category is mainly formed by hosts with a Haemoproteus infection, although these levels are much lower than those generally associated with acute primary infections . In total, the free-living bird samples contained 54.5% non-infected, 29.2% low parasitaemia and 16.2% high-parasitaemia individuals (n = 156 birds incl. experimental birds before infection).
|
study
| 100.0 |
We followed the same experimental protocols throughout all metabolic measurements: (i) we placed birds in holding cages with access to water but no food for 3 h before starting the RMR measurements, (ii) we then placed them in respirometers within a constant-temperature cabinet and measured RMR overnight, (iii) birds were returned to holding cages the next morning and given free access to food and water for about 3–4 h, (iv) we then measured their MMR and, lastly (v) we took a blood sample at completion of MMR to determine each bird's infection status, parasitaemia and haemoglobin concentration.
|
study
| 100.0 |
By contrast to naturally infected birds, which were only measured once, birds of the experimental groups were measured repeatedly: an initial measurement made on average 9 days before inoculation (range: 4–16 days), a second measurement during the acute-infection stage (approx. 23 days post inoculation; range: 14–34 days) and finally, during the chronic infection stage (approx. 34 days post inoculation; range 31–41 days).
|
study
| 100.0 |
To examine the consequences of infections on metabolic rates, we tested whether RMR or MMR changed with infections and/or parasitaemia. In addition to metabolic rates, we also considered other variables that may relate to aerobic performance: the time to exhaustion, and haemoglobin content of whole blood. As metabolic rates scale with body mass and often change seasonally, we included body mass and time of the season as covariates in the models. Data of metabolic rates, body mass, haemoglobin content and time to exhaustion were log10 transformed before analyses.
|
study
| 100.0 |
The statistical approaches and general models were equivalent for experimental and natural infections, with a few exceptions: we used linear models to test how the above output measures changed with infection status, time of season/experimental stage and body mass. As individuals were repeatedly measured in the infection experiment and thus, data were non-independent, we used linear mixed effects models, including bird-ID as random factor for the experimental infections and simple linear models for the natural infections.
|
study
| 100.0 |
Specifically for the experiment, the models related RMR, MMR and the other output measures to the interaction of experimental group (‘experimental’ and ‘control’) and phases of the experiment (‘before’ experimental infection, during ‘acute’ or ‘chronic’ phase of infection), while controlling for repeated measurements. We applied Bayesian simulation techniques to compute posterior probabilities for differences between experimental groups. All analyses were run in R (v. 3.3.2) , using the R-packages ‘arm’ (v. 1.9–3) and ‘lme4’ (v. 1.1-12) . As the lmer function does not provide p-values, we considered factors with absolute t-values greater than 2 significant at the p < 0.05 level following suggestions in .
|
study
| 100.0 |
The median parasitaemia in experimental birds was zero before infection, peaked to 0.030% (range: 0.004–0.548%) during the acute phase and dropped to 0.007% during the chronic phase (range: 0–0.038%) (figure 1a). Parasitaemia in the control group remained zero throughout. Figure 1.Parasitaemia in experimentally treated and naturally infected great reed warblers. (a) Frequency of parasitaemia of the lineage pGRW04 induced in the experimental birds during the acute phase of infection (n = 16) and (b) total frequency of parasitaemia in chronically infected wild birds (n = 61). (c) Genus-specific parasitaemia (medians ± 25/75% and the ranges) in wild birds for Plasmodium ssp. (red, n = 18) and Haemoproteus ssp. (dark grey, n = 40).
|
study
| 100.0 |
Parasitaemia in experimentally treated and naturally infected great reed warblers. (a) Frequency of parasitaemia of the lineage pGRW04 induced in the experimental birds during the acute phase of infection (n = 16) and (b) total frequency of parasitaemia in chronically infected wild birds (n = 61). (c) Genus-specific parasitaemia (medians ± 25/75% and the ranges) in wild birds for Plasmodium ssp. (red, n = 18) and Haemoproteus ssp. (dark grey, n = 40).
|
study
| 100.0 |
By contrast, parasitaemia in freshly captured wild birds averaged 0.103% (figure 1b), with Plasmodium infections having lower median parasitaemia (0.006%) than Haemoproteus infections (0.239%) (figure 1c). Thus, naturally infected birds showed a greater range of parasitaemia, and had parasitaemia levels about twofold higher than experimentally infected birds during their acute-infection stage.
|
study
| 100.0 |
Whole-body RMR in captive birds was much lower before inoculation than at both early and late post-inoculation stages (figure 2), but did not differ between experimentally infected and control individuals at any stage of measurement (figure 2; electronic supplementary material, table S1). Figure 2.Aerobic performance, haemoglobin content, and body mass of experimentally infected and sham-treated (non-infected) great reed warblers during sequential phases of infection with Plasmodium relictum. The aerobic performance is described as oxygen consumption (V̇O2, in ml min−1) during overnight rest (RMR), and during strenuous exercise (MMR), as well as the endurance of exercise period (time until exhaustion, min). Infected individuals during acute and chronic infection phases (early and late post-inoculation) did not differ from the control group, with all birds showing increasing whole-body metabolic rates and haemoglobin concentrations during the course of the experiment. Data are medians ± 25/75%.
|
study
| 100.0 |
Aerobic performance, haemoglobin content, and body mass of experimentally infected and sham-treated (non-infected) great reed warblers during sequential phases of infection with Plasmodium relictum. The aerobic performance is described as oxygen consumption (V̇O2, in ml min−1) during overnight rest (RMR), and during strenuous exercise (MMR), as well as the endurance of exercise period (time until exhaustion, min). Infected individuals during acute and chronic infection phases (early and late post-inoculation) did not differ from the control group, with all birds showing increasing whole-body metabolic rates and haemoglobin concentrations during the course of the experiment. Data are medians ± 25/75%.
|
study
| 100.0 |
In wild-caught birds, RMR increased significantly from late-breeding to both post-breeding and migration periods (p < 0.05 and 0.01, respectively; figure 3). Within all stages, RMR of non-infected birds was indistinguishable from those with low parasitaemia (t = −1.40, p = 0.27); however, birds with high parasitaemia had significantly lower RMR during the migration period compared to non-infected birds (t = −2.11, p = 0.04). Figure 3.Aerobic performance, haemoglobin concentration and body mass of free-living non-infected and chronically infected great reed warblers during sequential stages of the annual cycle. Infected birds were subdivided into low- and high-parasitaemia birds. Infection status had no effect on aerobic performance, haemoglobin content or period of exercise endurance during any stage we sampled. Thus, birds with chronic low and high parasitaemia were as aerobically capable as their non-infected counterparts, even during the migration phase. Data are medians ± 25/75%.
|
study
| 100.0 |
Aerobic performance, haemoglobin concentration and body mass of free-living non-infected and chronically infected great reed warblers during sequential stages of the annual cycle. Infected birds were subdivided into low- and high-parasitaemia birds. Infection status had no effect on aerobic performance, haemoglobin content or period of exercise endurance during any stage we sampled. Thus, birds with chronic low and high parasitaemia were as aerobically capable as their non-infected counterparts, even during the migration phase. Data are medians ± 25/75%.
|
study
| 100.0 |
Surprisingly, MMR did not differ between experimentally infected and control birds at any phase of the experiment (t = −0.20; figure 2), nor did it differ between free-living birds with zero, low or high parasitaemia at any period (p > 0.47; figure 3; electronic supplementary material, table S2). However, MMR changed greatly over the study period in both captive and wild birds. In experimental birds, MMR increased by about 50% from pre-inoculation to early post-inoculation phases and remained high until the end of the experiment (figure 2). Although these rises in MMR paralleled increases in body mass in captive birds (figure 2), MMR increased relatively more than mass and much of this mass-increase was associated with fat accumulation (electronic supplementary material, figure S1), which has negligible metabolic activity.
|
study
| 100.0 |
The time to exhaustion increased over the experimental period from an average of 2.8 to 6.1 min in captive birds, but was not different between infected and non-infected cohorts (t = −0.42; figure 2; electronic supplementary material, table S1). In wild-caught individuals, the time to exhaustion also increased significantly over the three life-history stages (p < 0.01), averaging about 30% and 65% higher during post-breeding and migration, respectively, than during the late-breeding stages (figure 3). Endurance times of infected free-living birds did not differ from their parasite-free conspecifics during any period of measurement (low parasitaemia: t = 1.42, high parasitaemia: t = −0.91). Thus, birds in migratory disposition could sustain energy-demanding exercise for much longer than at earlier phases, irrespective of parasitaemia.
|
study
| 100.0 |
All captive birds in the experiment gained substantial mass over the course of the study, with an increase of about 46% from the pre-inoculation to the late post-inoculation periods (figure 2). The visible subcutaneous fat stores of these birds increased significantly from pre-inoculation until the early post-inoculation period (t = 7.71) and increased somewhat further during the late post-inoculation period (electronic supplementary material, figure S1 and table S1). The pectoral muscle size also increased over these periods, but this muscle score only statistically differed between late post-inoculation and the pre-inoculation stages (t = 3.46).
|
study
| 100.0 |
Free-living birds also increased body mass over the study period, but not to the same extent as in captives (figure 3). Fat scores also increased in free-living birds over the course of our measurements, but never reached the levels of captive birds that had access to food ad libitum (electronic supplementary material, figure S2). Pectoral muscle scores were less variable between stages in free-living birds, but were higher during the migration stage (t = 3.23, p = 0.002; electronic supplementary material, table S2). Importantly, parasitaemia had no effect on any of these morphological variables at any stage we sampled (electronic supplementary material, tables S1 and S2).
|
study
| 100.0 |
Similar to the lack of effect of haemosporidian infection on aerobic performance, haemoglobin concentration did not differ between infected and non-infected captive birds (t = −1.21; figure 2), indicating minimal damage to haemoglobin at the low-parasitaemia levels that Plasmodium strain pGRW04 elicited in great reed warblers. Similarly, haemoglobin concentration did not differ between non-infected free-living birds and those with either low or high parasitaemia over the course of our study (both p > 0.95; figure 3). By contrast, haemoglobin concentration increased significantly from late-breeding to subsequent periods (p < 0.05 and 0.001 for post-breeding and migration periods, respectively), reaching levels about 11% higher during migration compared with late-breeding stages (figure 3).
|
study
| 100.0 |
Our study provides empirical and experimental evidence that aerobic performance is not adversely affected in malaria-infected birds with low parasitaemia. Furthermore, chronically infected birds did not differ from their uninfected counterparts in phenotypic attributes associated with preparations for migration, such as accumulation of lipid stores, increased body mass and higher total haemoglobin concentration in blood . Consequently, birds with low parasitaemia, which typifies birds with chronic infections, appear to have the same migratory capacity as uninfected birds.
|
study
| 100.0 |
We derived our experimental results from a well-established host–parasite pair: the P. relictum lineage pGRW04 is a host generalist (recorded in 75 host species of 22 bird families around the globe, http://mbio-serv2.mbioekol.lu.se/Malavi/ (accessed 14 September 2017)) and has been frequently found in great reed warbler-breeding populations in Europe as well as non-breeding populations in Africa . We are confident that the results of our study are robust because both the experimental manipulation as well as the observations on wild, naturally infected adults with higher parasitaemia by Plasmodium and Haemoproteus showed the same pattern in metabolic rates (see below).
|
study
| 100.0 |
Our results consistently showed that low parasitaemia during the acute or chronic phases of infection did not alter the maintenance metabolism, suggesting that the immune defences in low-parasitaemia settings are energetically frugal, unlike the significant rises in RMR displayed by strong immune responses .
|
study
| 100.0 |
Unexpectedly, birds with a higher natural parasitaemia showed a reduced RMR, a pattern also found in immunologically naive canaries when experimentally infected with Plasmodium . As the nocturnal oxygen consumption in most birds in our study showed marked fluctuations during the migration period, it is unclear whether the lower RMR in the high-parasitaemia group was a result of hypometabolism per se or was a consequence of reduced nocturnal restlessness, a behaviour well known in migrating birds .
|
study
| 100.0 |
Also in contrast to our expectations, both MMR and endurance times were not affected by infection. Both are fundamentally coupled to the internal oxygen transport capacity and, therefore, we argue that a low parasitaemia does not greatly reduce oxygen transport or uptake, and any minor effect of infection on oxygen transport was greatly outweighed by inter-individual variability across all life-history stages examined.
|
study
| 100.0 |
We found a striking seasonal pattern in RMR and MMR, with both increasing considerably towards the migration period. Birds preparing for migration had higher BMRs , higher aerobic capacity and could sustain exercise longer. Importantly, this pattern was shared by experimentally treated and control birds as well as wild birds.
|
study
| 99.9 |
Higher metabolic rates require higher oxygen supply to the mitochondria, which is facilitated by higher total haemoglobin content of blood (figures 2 and 3) or likewise by elevated haematocrit . In parallel with the shared increases in aerobic capacity in the pre-migratory phase, non-infected and infected hosts displayed significant increases in accumulated fuel (in the form of body fat) and increased breast muscles at similar rates leading up to this period.
|
study
| 100.0 |
Because we found infected and uninfected migratory birds to be indistinguishable in MMRs and exercise endurance and to share morphological adjustments commensurate with migratory preparation, we conclude that low-parasitaemia birds will have the same migratory capacity as uninfected individuals. Assuming flight speed is physiologically constrained by aerobic capacity, our results suggest that chronically infected migrants are able to fly at speeds similar to uninfected individuals and we do not expect differences in the duration of flight bouts. There is ambiguous evidence for haematozoan infections to affect migration in passerines: blood parasites can delay arrival on the breeding grounds of migrants or they have no effect on arrival times . However, arrival might mainly be determined by factors other than flight speed because migrants usually spend more than 80% of total migration time at stopover sites . Thus, infected and uninfected individuals can still differ in the timing of migration if, e.g. the efficiency of fundamental stopover behaviour like foraging and fuelling is hampered by the parasite and results in a later departure in infected birds than their non-infected counterparts.
|
study
| 100.0 |
Even if chronically infected birds arrive later, they still have the physiological capacity to migrate successfully over long distances, thus, they are mobile reservoirs for infections of conspecifics and unrelated species at stopover and at breeding sites. The consequences of such haematozoan infections on immunologically naive hosts can vary markedly, ranging from those that are totally refractory to infection to others that are highly compromised .
|
other
| 99.9 |
Our study has advanced our understanding of the interaction between blood parasites and their migratory hosts. We have excluded one long-speculated effect of these parasites—namely that on aerobic performance. Thus, if infected migratory hosts differ from uninfected conspecifics in any phenological measure, e.g. departure or arrival times, clutch size, or reproduction success, other mechanisms besides parasite-induced changes in aerobic capacity must be involved.
|
study
| 100.0 |
It was estimated that 400 million people were infected with viral hepatitis B, and 6 and about 10 million are newly infected every year.1 The World Health Organization (WHO) projected that 2 to 3 million deaths can be avoided every year through immunization.2 Chronic hepatitis B virus (HBV) infection was the commonest cause of hepatocellular carcinoma.3 Viral hepatitis was mostly transmitted through the mother-to-child mode.4 The risk of transmitting HBV from the mothers to the newborns accounted approximately 12% when mothers have a high hepatitis B viral load.5 The prevalence of HBV varied by geographical areas, the places of the delivery, the residence, the affluence, and the ethnicity.5
|
review
| 99.9 |
The immunization against HBV is considered the most effective way to control and prevent this major life-threatening communicable disease. It can prevent the infection and development of chronic disease and liver cancer due to hepatitis B (95% effectiveness).2
|
other
| 99.94 |
In 1992, the WHO set a goal that all member states shall introduce hepatitis B vaccine into the Universal Childhood Hepatitis B vaccination by 1997. It set up the elimination targets of less than 2% by 2012 and of less than 1% by year 2017. By 2005, the vaccination coverage shall be at least 80% of birth cohorts in every district receiving three doses of hepatitis B vaccine.7-9
|
other
| 99.94 |
The National Immunization Programme (NIP) developed a Comprehensive Multi-Year Strategic Plan, 2016 to 2020, covering five areas namely service delivery, behavioral communication, cold chain management, vaccine preventable disease surveillance, and program management to reach the immunization’s set targets.10
|
other
| 99.94 |
Interview key stakeholders including NIP’s management at national (NIP, Financing, CMS), subnational (PHDO, ODO, RH, HC), and community (VHSG), partners (WHO, United Nations International Children’s Emergency Fund [UNICEF], Global Alliance for Vaccination Initiative [GAVI], RACHA)
|
other
| 99.94 |
There are a number of key policies, strategic plans, guidelines, and SOPs, which were developed by the NIP. Those listed are National Immunization Committee, National Policy 2012, Strategic Plan 2016 to 2020 (2016), National Strategy for the Introduction of Hepatitis B Vaccine, User Guide for Refrigerator Temperature Monitoring Using Fridge-Tag 2014, and Operation Guidelines Surveillance of Adverse Events Following Immunization (AEFI) 2015.11
|
other
| 99.94 |
Currently, the NIP’s vaccination calendar is comprised of nine types of vaccines, namely Bacillus Calmette Guerin (BCG), hepatitis B, oral polio vaccine, diphtheria-polio-tetanus-hepatitis B-hemophilus influenza B (DPT-HepB-Hib), pneumococcal conjugate vaccine (PCV13), inactivated polio vaccine, measles/ rubella at 9 months (MR9), measles/rubella at 18 months (MR18), and Japanese encephalitis.10
|
other
| 99.94 |
All levels of the health system (national, provincial, district, health centers) are required to develop planning including routine and supplementary immunization activities. The routine immunization consists of fixed and outreach sessions. Fixed sites include health centers and hospitals. The maternity ward provides only HepB birthdose and BCG.10
|
other
| 99.94 |
The prevalence of hepatitis B vaccine has decreased slightly from year-to-year and from one province to another depending on different factors (Graph 1). The prevalence was 3.5% (2.40-4.80%) in 2001 and 3.40% (2.50-4.30%) in 2006 and 1.41% in the Kratie province in 2011 (3.45% in Rattanakiri province and 0.33% in Phnom Penh). The seroprevalence survey 2016 will be conducted in early 2017.12-14
|
other
| 71.1 |
The coverage of hepatitis B vaccine has increased constantly and is very high for both hepatitis B vaccine birth doses (BD) and DPT-HepB (Graph 2). The coverage of the hepatitis B birth dose doubled from 44.0% in 2006 up to 84.0% in 2015; DPT-HepB from 85% in 2006 up to 98.0% in 2015.15
|
other
| 99.75 |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.