Angiogenesis-independent endothelial protection of liver: role of VEGFR-1

The vascular endothelium was once thought to function primarily in nutrient and oxygen delivery, but recent evidence suggests that it may play a broader role in tissue homeostasis. To explore the role of sinusoidal endothelial cells (LSECs) in the adult liver, we studied the effects of vascular endothelial growth factor (VEGF) receptor activation on mouse hepatocyte growth. Delivery of VEGF-A increased liver mass in mice but did not stimulate growth of hepatocytes in vitro, unless LSECs were also present in the culture. Hepatocyte growth factor (HGF) was identified as one of the LSEC-derived paracrine mediators promoting hepatocyte growth. Selective activation of VEGF receptor-1 (VEGFR-1) stimulated hepatocyte but not endothelial proliferation in vivo and reduced liver damage in mice exposed to a hepatotoxin. Thus, VEGFR-1 agonists may have therapeutic potential for preservation of organ function in certain liver disorders.     

Influence of Stabilized-Dewatered Sludge Addition on Solid-Phase Clean-Up of a Soil Contaminated By Phenolic Compounds

The purpose of this work was to investigate the effect of stabilized-dewatered sludge on the performances of a solid-phase biological treatment applied to a soil contaminated with phenolic compounds.To this aim, a soil sample was artificially contaminated with either phenol or 3-chlorophenol, with concentrations of 1 and 0.5 g kg^-1 of soil, respectively. Each contaminated soil sample was treated with a solid phase process, performed in three different operating conditions: without any addition; with addition of nutrients; with addition of nutrients and stabilized-dewatered sludge, obtained from a domestic wastewater treatment plant. The results obtained clearly indicated that the use of stabilized-dewatered sludge greatly reduced the time for complete removal of both phenol and 3-chlorophenol. Besides, the microorganisms concentration was higher in the sludge-amended soil with respect to other samples. This behavior could be a consequence of the carbon and energy sources contained in the sludge, even if the sludge could also offer a source of phenols-degrading microorganisms. On the contrary, the simple addition of nutrient did not notably affect the solid phase treatment under the studied conditions. Based on these results, it was shown that the use of stabilized-dewatered sludge may represent an efficient and economical way for accelerating solid-phase treatments, since it is produced worldwide and in large quantities as residue of domestic wastewater plants.     

Xylella fastidiosa subsp. pauca ST53 exploits pit membranes of susceptible olive cultivars to spread systemically in the xylem

Xylella fastidiosa subspecies pauca strain De Donno (XfDD) ST53 is the causal agent of olive quick decline syndrome, a severe disease first described in Apulia, Italy. Although the two local cultivars Cellina di Nardò and Ogliarola Salentina showed high susceptibility, traits of resistance to the bacterium were found in the cultivar Leccino. Previous studies in field-grown olives suggested that vascular occlusions and anatomophysiological properties of the different cultivars played a role in the olive response to XfDD. The present investigation reports observations at the early stage of the infection on artificially inoculated olives. Electron microscope studies showed that XfDD exploits the pit membranes (PMs) of the susceptible cultivar Cellina di Nardò to spread systemically. In this cultivar, PMs were degraded upon XfDD infection, suggesting activity of bacterial cell wall-degrading enzymes. Moreover, occluded vessels contained an amorphous electrondense matrix resembling gum. Conversely, in Leccino, occluded vessels were mainly filled by callose-like granules that tightly entrapped XfDD cells. In addition, PMs from Leccino had a compact undegraded structure that was not permeable to XfDD. Our study suggests that exploitation of PMs is a key event in the infection process of X. fastidiosa subsp. pauca ST53 in susceptible olive cultivars.