Quinoides and VEGFR2 TKIs influence the fate of hepatocellular carcinoma and its cancer stem cells

Bioactivities of quinoides 1-5 and VEGFR2 TKIs 6-10 in hepatocellular cancer (HCC) and cancer stem cells (HCSCs) were studied. The compounds exhibited IC50 values in μM concentrations in HCC cells. Quinoide 3 was able to eradicate cancer stem cells, similar to the action of the stem cell inhibitor DAPT. However, the more cytotoxic VEFGR TKIs (IC50: 0.4-3.0 μM) including sorafenib, which is the only FDA approved drug for the treatment of HCC, enriched the hepatocellular cancer stem cell population by 2-3 fold after treatment. An aggressiveness factor (AF) was proposed to quantify the characteristics of drug candidates for their ability to eradicate the CSC subpopulation. Considering the tumour heterogeneity and marker positive cancer stem cell like subpopulation enrichment upon treatments in patients, this study emphasises the importance of the chemotherapeutic agent choice acting differentially on all the subpopulations including marker-positive CSCs. © The Royal Society of Chemistry

Above-ground biomass and structure of 260 African tropical forests.

We report above-ground biomass (AGB), basal area, stem density and wood mass density estimates from 260 sample plots (mean size: 1.2 ha) in intact closed-canopy tropical forests across 12 African countries. Mean AGB is 395.7 Mg dry mass ha⁻¹ (95% CI: 14.3), substantially higher than Amazonian values, with the Congo Basin and contiguous forest region attaining AGB values (429 Mg ha⁻¹) similar to those of Bornean forests, and significantly greater than East or West African forests. AGB therefore appears generally higher in palaeo- compared with neotropical forests. However, mean stem density is low (426 ± 11 stems ha⁻¹ greater than or equal to 100 mm diameter) compared with both Amazonian and Bornean forests (cf. approx. 600) and is the signature structural feature of African tropical forests. While spatial autocorrelation complicates analyses, AGB shows a positive relationship with rainfall in the driest nine months of the year, and an opposite association with the wettest three months of the year; a negative relationship with temperature; positive relationship with clay-rich soils; and negative relationships with C : N ratio (suggesting a positive soil phosphorus-AGB relationship), and soil fertility computed as the sum of base cations. The results indicate that AGB is mediated by both climate and soils, and suggest that the AGB of African closed-canopy tropical forests may be particularly sensitive to future precipitation and temperature changes

EGR control on operation of a tar tolerant HCCI engine with simulated syngas from biomass

In combined heat and power plants operated with biomass syngas, the removal of condensible tars is a necessary but expensive step (up to one third of the installation and maintenance costs). This step is required because the syngas has to be cooled down to avoid knocking in the spark ignition engines traditionally used in such plants. To remove the tar condensation problem, we developed an alternative system based on an Homogeneous Charge Compression Ignition (HCCI) engine operated at intake temperatures above the tar dew point. To address the challenge of power derating of such engine setups, the current paper focuses on the application of Exhaust Gas Recirculation (EGR) as a control parameter that would indirectly allow the improvement of the engine performance. Based on a conservative estimate of tar dew points, HCCI combustion was studied at an intake temperature of 250 °C using synthetic biomass syngas and synthetic EGR on a mono-cylinder HCCI engine operated at 1000 RPM. The effects of charge dilution, thermal and kinetic damping due to the EGR gases were also analysed to understand their main effects. The use of EGR successfully increased the maximum achievable Indicated Mean Effective Pressure from 2.5 bar at EGR = 0% up to 3.3 bar at EGR = 25%, through damping the maximum pressure rise rate and allowing higher equivalence ratios. © 2017 Elsevier Lt