Comment on 'A first map of tropical Africa's above-ground biomass derived from satellite imagery'

Copyright Institute of Physics © 2011We present a critical evaluation of the above-ground biomass (AGB) map of Africa published in this journal by Baccini et al (2008 Environ. Res. Lett. 3 045011). We first test their map against an independent dataset of 1154 scientific inventory plots from 16 African countries, and find only weak correspondence between our field plots and the AGB value given for the surrounding 1 km pixel by Baccini et al. Separating our field data using a continental landcover classification suggests that the Baccini et al map underestimates the AGB of forests and woodlands, while overestimating the AGB of savannas and grasslands. Secondly, we compare their map to 216 000 × 0.25 ha spaceborne LiDAR footprints. A comparison between Lorey's height (basal-area-weighted average height) derived from the LiDAR data for 1 km pixels containing at least five LiDAR footprints again does not support the hypothesis that the Baccini et al map is accurate, and suggests that it significantly underestimates the AGB of higher AGB areas. We conclude that this is due to the unsuitability of some of the field data used by Baccini et al to create their map, and overfitting in their model, resulting in low accuracies outside the small areas from which their field data are drawn

Dissolved organic carbon transformations and microbial community response to variations in recharge waters in a shallow carbonate aquifer

© 2016, The Author(s). In carbonate aquifers, dissolved organic carbon from the surface drives heterotrophic metabolism, generating CO2 in the subsurface. Although this has been a proposed mechanism for enhanced dissolution at the water table, respiration rates and their controlling factors have not been widely evaluated. This study investigates the composition and concentration of dissolved organic carbon (DOC) reaching the water table from different recharge pathways on a subtropical carbonate island using a combination of DOC concentration measurements, fluorescence and absorption characterisation. In addition, direct measurements of the microbial response to the differing water types were made. Interactions of rainfall with the vegetation, via throughfall and stemflow, increase the concentration of DOC. The highest DOC concentrations are associated with stemflow, overland recharge and dissolution hole waters which interact with bark lignin and exhibit strong terrestrial-derived characteristics. The groundwater samples exhibit the lowest concentrations of DOC and are comprised of refractory humic-like organic matter. The heterotrophic response seems to be controlled by the concentration of DOC in the sample. The terrestrially sourced humic-like matter in the stemflow and dissolution hole samples was highly labile, thus increasing the amount of biologically produced CO2 to drive dissolution. Based on the calculated respiration rates, microbial activity could enhance carbonate dissolution, increasing porosity generation by a maximum of 1%kyr−1 at the top of the freshwater lens

Genetic diversity and population structure of Ascochyta rabiei from the western Iranian Ilam and Kermanshah provinces using MAT and SSR markers

Knowledge of genetic diversity in A. rabiei provides different levels of information that are important in the management of crop germplasm resources. Gene flow on a regional level indicates a significant potential risk for the regional spread of novel alleles that might contribute to fungicide resistance or the breakdown of resistance genes. Simple sequence repeat (SSR) and mating type (MAT) markers were used to determine the genetic structure, and estimate genetic diversity and the prevalence of mating types in 103 Ascochyta rabiei isolates from seven counties in the Ilam and Kermanshah provinces of western Iran (Ilam, Aseman abad, Holaylan, Chardavol, Dareh shahr, Gilangharb, and Sarpul). A set of 3 microsatellite primer pairs revealed a total of 75 alleles; the number of alleles varied from 15 to 34 for each marker. A high level of genetic variability was observed among A. rabiei isolates in the region. Genetic diversity was high (He = 0.788) within populations with corresponding high average gene flow and low genetic distances between populations. The smallest genetic distance was observed between isolates from Ilam and Chardavol. Both mating types were present in all populations, with the majority of the isolates belonging to Mat1-1 (64%), but within populations the proportions of each mating type were not significantly different from 50%. Results from this study will be useful in breeding for Ascochyta blight-resistant cultivars and developing necessary control measures

"Poker" association of weekly alternating 5-fluorouracil, irinotecan, bevacizumab and oxaliplatin (FIr-B/FOx) in first line treatment of metastatic colorectal cancer: a phase II study

<p>Abstract</p> <p>Background</p> <p>This phase II study investigated efficacy and safety of weekly alternating Bevacizumab (BEV)/Irinotecan (CPT-11) or Oxaliplatin (OHP) associated to weekly 5-Fluorouracil (5-FU) in first line treatment of metastatic colorectal carcinoma (MCRC).</p> <p>Methods</p> <p>Simon two-step design: delta 20% (p₀50%, p₁70%), power 80%, α 5%, β 20%. Projected objective responses (ORR): I step, 8/15 patients (pts); II step 26/43 pts. Schedule: weekly 12 h-timed-flat-infusion/5-FU 900 mg/m², days 1-2, 8-9, 15-16, 22-23; CPT-11 160 mg/m²plus BEV 5 mg/kg, days 1,15; OHP at three dose-levels, 60-70-80 mg/m², days 8, 22; every 4 weeks.</p> <p>Results</p> <p>Fifty consecutive, unselected pts < 75 years were enrolled: median age 63; young-elderly (yE) 24 (48%); liver metastases (LM) 33 pts, 66% Achieved OHP recommended dose, 80 mg/m². ORR 82% intent-to-treat and 84% as-treated analysis. Median progression-free survival 12 months. Equivalent efficacy was obtained in yE pts. Liver metastasectomies were performed in 26% of all pts and in 39% of pts with LM. After a median follow-up of 21 months, median overall survival was 28 months. Cumulative G3-4 toxicities per patient: diarrhea 28%, mucositis 6%, neutropenia 10%, hypertension 2%. They were equivalent in yE pts. Limiting toxicity syndromes (LTS), consisting of the dose-limiting toxicity, associated or not to G2 or limiting toxicities: 44% overall, 46% in yE. Multiple versus single site LTS, respectively: overall, 24% versus 20%; yE pts, 37.5% versus 8%.</p> <p>Conclusion</p> <p>Poker combination shows high activity and efficacy in first line treatment of MCRC. It increases liver metastasectomies rate and can be safely administered.</p> <p>Trial registration</p> <p>Osservatorio Nazionale sulla Sperimentazione Clinica dei Medicinali (OsSC) Agenzia Italiana del Farmaco (AIFA) Numero EudraCT 2007-004946-34</p

Capecitabine and bevacizumab as first-line treatment in elderly patients with metastatic colorectal cancer

BACKGROUND: The efficacy and safety of capecitabine and bevacizumab in elderly patients with metastatic colorectal cancer (mCRC) considered unsuitable for receiving first-line chemotherapy with an irinotecan or oxaliplatin-based combination were assessed in a phase II, open, multicentre, uncontrolled study. METHODS: Treatment consisted of capecitabine 1250 mgm 2 (or 950 mgm 2 for patients with a creatinine clearance of 30–50ml min 1) twice daily on days 1–14 and bevacizumab (7.5 mg kg 1) on day 1 every 3 weeks. RESULTS: A total of 59 patients aged X70 years with mCRC were enrolled. In an intention-to-treat analysis, the overall response rate was 34%, with 71% of patients achieving disease control. Median progression-free survival and overall survival were 10.8 months and 18 months, respectively. In all, 32 patients (54%) had grade 3/4 adverse events (AEs), the most common being hand–foot syndrome (19%), diarrhoea (9%) and deep venous thrombosis (7%). Four patients died because of treatment-related AEs. A relationship was detected between creatinine clearance p50 ml min 1 and the development of non-bevacizumab-related grade 3/4 AEs. The incidence of bevacizumab-associated AEs (hypertension, thromboembolic events and proteinuria) was consistent with that of previous reports in elderly patients. CONCLUSION: Bevacizumab combined with capecitabine represents a valid therapeutic alternative in elderly patients considered to be unsuitable for receiving polychemotherapy.This study was supported by Hoffmann-La Roche, Nutley, NJ, USA

Sensitivity of Five Rapid HIV Tests on Oral Fluid or Finger-Stick Whole Blood: A Real-Time Comparison in a Healthcare Setting

BACKGROUND: Health authorities in several countries recently recommended the expansion of human immunodeficiency virus (HIV) antibody testing, including the use of rapid tests. Several HIV rapid tests are now licensed in Europe but their sensitivity on total blood and/or oral fluid in routine healthcare settings is not known. METHODS AND FINDINGS: 200 adults with documented HIV-1 (n=194) or HIV-2 infection (n=6) were prospectively screened with five HIV rapid tests using either oral fluid (OF) or finger-stick whole blood (FSB). The OraQuick Advance rapid HIV1/2 was first applied to OF and then to FSB, while the other tests were applied to FSB, in the following order: Vikia HIV 1/2, Determine HIV 1-2, Determine HIV-1/2 Ag/Ab Combo and INSTI HIV-1/HIV-2. Tests negative on FSB were repeated on paired serum samples. Twenty randomly selected HIV-seronegative subjects served as controls, and the results were read blindly. Most patients had HIV-1 subtype B infection (63.3%) and most were on antiretroviral therapy (68.5%). Sensitivity was 86.5%, 94.5%, 98.5%, 94.9%, 95.8% and 99% respectively, with OraQuick OF, OraQuick FSB, Vikia, Determine, Determine Ag/Ab Combo and INSTI (p<0.0001). OraQuick was less sensitive on OF than on FSB (p=0.008). Among the six patients with three or more negative tests, two had recent HIV infection and four patients on antiretroviral therapy had undetectable plasma viral load. When patients positive in all the tests were compared with patients who had at least one negative test, only a plasma HIV RNA level<200 cp/ml was significantly associated with a false-negative result (p=0.009). When the 33 rapid tests negative on FSB were repeated on serum, all but six (5 negative with OraQuick, 1 with INSTI) were positive. The sensitivity of OraQuick, Determine and Determine Ag/Ab Combo was significantly better on serum than on FSB (97.5%, p=0.04; 100%, p=0.004; and 100%, p=0.02, respectively). CONCLUSION: When evaluated in a healthcare setting, rapid HIV tests were less sensitive on oral fluid than on finger-stick whole blood and less sensitive on finger-stick whole blood than on serum

Gene expression changes induced by the tumorigenic pyrrolizidine alkaloid riddelliine in liver of Big Blue rats

<p>Abstract</p> <p>Background</p> <p>Pyrrolizidine alkaloids (PAs) are probably the most common plant constituents that poison livestock, wildlife, and humans worldwide. Riddelliine is isolated from plants grown in the western United States and is a prototype of genotoxic PAs. Riddelliine was used to investigate the genotoxic effects of PAs via analysis of gene expression in the target tissue of rats in this study. Previously we observed that the mutant frequency in the liver of rats gavaged with riddelliine was 3-fold higher than that in the control group. Molecular analysis of the mutants indicated that there was a statistically significant difference between the mutational spectra from riddelliine-treated and control rats.</p> <p>Results</p> <p>Riddelliine-induced gene expression profiles in livers of Big Blue transgenic rats were determined. The female rats were gavaged with riddelliine at a dose of 1 mg/kg body weight 5 days a week for 12 weeks. Rat whole genome microarray was used to perform genome-wide gene expression studies. When a cutoff value of a two-fold change and a <it>P</it>-value less than 0.01 were used as gene selection criteria, 919 genes were identified as differentially expressed in riddelliine-treated rats compared to the control animals. By analysis with the Ingenuity Pathway Analysis Network, we found that these significantly changed genes were mainly involved in cancer, cell death, tissue development, cellular movement, tissue morphology, cell-to-cell signaling and interaction, and cellular growth and proliferation. We further analyzed the genes involved in metabolism, injury of endothelial cells, liver abnormalities, and cancer development in detail.</p> <p>Conclusion</p> <p>The alterations in gene expression were directly related to the pathological outcomes reported previously. These results provided further insight into the mechanisms involved in toxicity and carcinogenesis after exposure to riddelliine, and permitted us to investigate the interaction of gene products inside the signaling networks.</p

The psychometric properties of the subscales of the GHQ-28 in a multi-ethnic maternal sample: results from the Born in Bradford cohort

Background: Poor maternal mental health can impact on children’s development and wellbeing; however, there is concern about the comparability of screening instruments administered to women of diverse ethnic origin. Methods: We used confirmatory factor analysis (CFA) and exploratory factor analysis (EFA) to examine the subscale structure of the GHQ-28 in an ethnically diverse community cohort of pregnant women in the UK (N = 5,089). We defined five groups according to ethnicity and language of administration, and also conducted a CFA between four groups of 1,095 women who completed the GHQ-28 both during and after pregnancy. Results: After item reduction, 17 of the 28 items were considered to relate to the same four underlying concepts in each group; however, there was variation in the response to individual items by women of different ethnic origin and this rendered between group comparisons problematic. The EFA revealed that these measurement difficulties might be related to variation in the underlying concepts being measured by the factors. Conclusions: We found little evidence to recommend the use of the GHQ-28 subscales in routine clinical or epidemiological assessment of maternal women in populations of diverse ethnicity

Systems Perspectives on the Interaction Between Human and Technological Resources

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