Can N2 O emissions offset the benefits from soil organic carbon storage?

To respect the Paris agreement targeting a limitation of global warming below 2°C by 2100, and possibly below 1.5°C, drastic reductions of greenhouse gas emissions are mandatory but not sufficient. Large-scale deployment of other climate mitigation strategies is also necessary. Among these, increasing soil organic carbon (SOC) stocks is an important lever because carbon in soils can be stored for long periods and land management options to achieve this already exist and have been widely tested. However, agricultural soils are also an important source of nitrous oxide (N2 O), a powerful greenhouse gas, and increasing SOC may influence N2 O emissions, likely causing an increase in many cases, thus tending to offset the climate change benefit from increased SOC storage. Here we review the main agricultural management options for increasing SOC stocks. We evaluate the amount of SOC that can be stored as well as resulting changes in N2 O emissions to better estimate the climate benefits of these management options. Based on quantitative data obtained from published meta-analyses and from our current level of understanding, we conclude that the climate mitigation induced by increased SOC storage is generally overestimated if associated N2 O emissions are not considered but, with the exception of reduced tillage, is never fully offset. Some options (e.g. biochar or non-pyrogenic C amendment application) may even decrease N2 O emissions.

Mepacrine antagonises tumour cell growth induced by natural polyamines.

BACKGROUND: Mepacrine is an antiproliferative agent, characterised by an aliphatic chain similar to that of natural polyamines whose activation is closely associated with cell proliferation and may lead to malignant transformation and neurodegenerative diseases. This study aims to investigate a possible antagonism between mepacrine and polyamines in tumour proliferation. MATERIALS AND METHODS: MCF-7 and Vero cells were cultured in Eagle's minimum essential medium and then subjected to graded concentrations of putrescine, spermine and spermidine alone and in combination with mepacrine. Methyl thiazole tetrazolium test and Western-blotting were performed. RESULTS: Putrescine and spermidine at 0.5 mg/l significantly stimulated cell growth, whereas mepacrine treatment confirmed the enhanced p21 expression previously reported by a recent study and growth inhibition. When used in combination, mepacrine antagonized MCF-7 growth induced by polyamines. CONCLUSION: Our results suggest that mepacrine may represent a choice in the treatment of tumours induced by the modified concentration of polyamines.

Effects of anti-malarial drugs on MCF-7 and Vero cell replication.

BACKGROUND: Previous in vivo studies performed in our laboratories demonstrated that anti-malarial drugs may or enhance or slow down Ehrlich's ascites tumour progression in infected mice. In the light of these observations, an in vitro study was undertaken to assess the response of human tumour cells to various anti-malarial drugs and consequently the safety of the anti-malarial therapy. MATERIALS AND METHODS: MCF-7 cells and Vero cells (control line) were cultured in Eagle's minimum Essential medium (EMEM) and then subjected to graded concentrations of different anti-malarial drugs. Trypan-blue exclusion, MTT and Western blotting tests were performed. RESULTS: The findings showed that pyrimethamine (12.5 mg/L), chloroquine (12.5 mg/L) and primaquine (1.56 mg/L) stimulated MCF-7 cell growth. The proliferative effect was inhibited by doxorubicin only in cultures treated with chloroquine and primaquine. These results might indicate that some anti-malarial drugs have a worrying tumour-promoting effect which should not be underestimated when undertaking anti-malarial prophylactic measures.

18beta-glycyrrhetinic acid and glabridin prevent oxidative DNA fragmentation in UVB-irradiated human keratinocyte cultures.

BACKGROUND: UVB radiation is the major etiological factor in the pathogenesis of skin aging and cancer development. New approaches to prevent and reverse UVB damage are needed to reduce sunlight-induced skin cancer. This study aimed to investigate a possible protective activity of liquorice root extracts glycyrrhizin (GL), 18ß-glycyrrhetinic acid (18ß-GA) and glabridin (GLB) against UVB radiation damage in human keratinocyte cultures. MATERIALS AND METHODS: The MTT test was performed to assess cell viability. DNA damage was evaluated by comet assay, whereas generation of intracellular reactive oxygen species (ROS) was measured by fluorescent 2'7'-dichlorodihydrofluorescein diacetate assay. In addition, the activation of p53, regulation of BCL-2 and PARP cleavage were analyzed by Western blot analysis. RESULTS: The treatment of human keratinocytes with 18ß-GA and GLB prevented direct and indirect DNA damage avoiding apoptosis activation. CONCLUSION: 18ß-glycyrrhetinic acid and glabridin are potent antioxidants that prevent oxidative DNA fragmentation and the activation of apoptosis-associated proteins in human keratinocytes.

Role of the pharmaceutical excipients in the tamoxifen activity on MCF-7 and vero cell cultures.

BACKGROUND: Microparticles are used for controlled drug delivery. With the aim of improving both bioavailability and tamoxifen selective toxicity, the activity of tamoxifen embedded in calcium alginate/chitosan microparticles was studied. MATERIALS AND METHODS: Tamoxifen alone and embedded in microparticles prepared with sodium alginate from Kelco (62% mannuronic acid and 38% guluronic acid) and from Fluka (30% mannuronic acid and 70% guluronic acid) was added to MCF-7 and Vero cultures and evaluated for antiproliferative activity by the MTT test. RESULTS: The use of Kelco or Fluka alginate resulted in different LD(50) values on Vero and MCF-7 cultures, showing a higher cytotoxicity toward Vero cells treated with tamoxifen embedded in Kelco microparticles (25 microM vs. 48 microM on MCF-7 cells) but a selective toxicity with Fluka microparticles (25 microM and 10 microM on Vero and MCF-7 cells respectively). CONCLUSION: Microparticle formulation may improve selective toxicity according to the alginate employed: differences in the chemical alginate composition can dramatically change both drug activity and toxicity.