Rac Inhibition Reverses the Phenotype of Fibrotic Fibroblasts

Background: Fibrosis, the excessive deposition of scar tissue by fibroblasts, is one of the largest groups of diseases for which there is no therapy. Fibroblasts from lesional areas of scleroderma patients possess elevated abilities to contract matrix and produce alpha-smooth muscle actin (alpha-SMA), type I collagen and CCN2 (connective tissue growth factor, CTGF). The basis for this phenomenon is poorly understood, and is a necessary prerequisite for developing novel, rational anti-fibrotic strategies.Methods and Findings: Compared to healthy skin fibroblasts, dermal fibroblasts cultured from lesional areas of scleroderma (SSc) patients possess elevated Rac activity. NSC23766, a Rac inhibitor, suppressed the persistent fibrotic phenotype of lesional SSc fibroblasts. NSC23766 caused a decrease in migration on and contraction of matrix, and alpha-SMA, type I collagen and CCN2 mRNA and protein expression. SSc fibroblasts possessed elevated Akt phosphorylation, which was also blocked by NSC23766. Overexpression of rac1 in normal fibroblasts induced matrix contraction and alpha-SMA, type I collagen and CCN2 mRNA and protein expression. Rac1 activity was blocked by PI3kinase/Akt inhibition. Basal fibroblast activity was not affected by NSC23766.Conclusion: Rac inhibition may be considered as a novel treatment for the fibrosis observed in SSc

Paxillin Mediates Sensing of Physical Cues and Regulates Directional Cell Motility by Controlling Lamellipodia Positioning

Physical interactions between cells and the extracellular matrix (ECM) guide directional migration by spatially controlling where cells form focal adhesions (FAs), which in turn regulate the extension of motile processes. Here we show that physical control of directional migration requires the FA scaffold protein paxillin. Using single-cell sized ECM islands to constrain cell shape, we found that fibroblasts cultured on square islands preferentially activated Rac and extended lamellipodia from corner, rather than side regions after 30 min stimulation with PDGF, but that cells lacking paxillin failed to restrict Rac activity to corners and formed small lamellipodia along their entire peripheries. This spatial preference was preceded by non-spatially constrained formation of both dorsal and lateral membrane ruffles from 5–10 min. Expression of paxillin N-terminal (paxN) or C-terminal (paxC) truncation mutants produced opposite, but complementary, effects on lamellipodia formation. Surprisingly, pax−/− and paxN cells also formed more circular dorsal ruffles (CDRs) than pax+ cells, while paxC cells formed fewer CDRs and extended larger lamellipodia even in the absence of PDGF. In a two-dimensional (2D) wound assay, pax−/− cells migrated at similar speeds to controls but lost directional persistence. Directional motility was rescued by expressing full-length paxillin or the N-terminus alone, but paxN cells migrated more slowly. In contrast, pax−/− and paxN cells exhibited increased migration in a three-dimensional (3D) invasion assay, with paxN cells invading Matrigel even in the absence of PDGF. These studies indicate that paxillin integrates physical and chemical motility signals by spatially constraining where cells will form motile processes, and thereby regulates directional migration both in 2D and 3D. These findings also suggest that CDRs may correspond to invasive protrusions that drive cell migration through 3D extracellular matrices

Diffuse glioma growth: a guerilla war

In contrast to almost all other brain tumors, diffuse gliomas infiltrate extensively in the neuropil. This growth pattern is a major factor in therapeutic failure. Diffuse infiltrative glioma cells show some similarities with guerilla warriors. Histopathologically, the tumor cells tend to invade individually or in small groups in between the dense network of neuronal and glial cell processes. Meanwhile, in large areas of diffuse gliomas the tumor cells abuse pre-existent “supply lines” for oxygen and nutrients rather than constructing their own. Radiological visualization of the invasive front of diffuse gliomas is difficult. Although the knowledge about migration of (tumor)cells is rapidly increasing, the exact molecular mechanisms underlying infiltration of glioma cells in the neuropil have not yet been elucidated. As the efficacy of conventional methods to fight diffuse infiltrative glioma cells is limited, a more targeted (“search & destroy”) tactic may be needed for these tumors. Hopefully, the study of original human glioma tissue and of genotypically and phenotypically relevant glioma models will soon provide information about the Achilles heel of diffuse infiltrative glioma cells that can be used for more effective therapeutic strategies

Agricultural ground penetrating radar response to deep cultivation across a fault scarp after the 4 September 2010 Darfield earthquake, Canterbury, New Zealand

The 4 September 2010 Darfield earthquake, New Zealand, produced a >; 28 km long approximately east-west surface rupture trace through high intensity arable and pastoral farmland. The sense of motion was mostly dextral strike-slip with a component of reverse faulting at depth. We acquired ground penetrating radar (GPR) images before and after specialist land rehabilitation equipment was used to reduce the relief across a 1.5 m high fault scarp and to fill in surface “cracks”. The upper 1-2 m was calibrated using a dynamic cone penetro meter (DCP). The effects of the deep tilling caused an increase in the shallow velocity, due to reworking of the soil, and a consequent “pull up” of the reflectors immediately beneath the tilled zone due to the reduced two-way travel time. The deeper structure and features in the profiles, in contrast, were largely unaffected. We also examined the effects of the system settings on the response. We used a Sensors & Software pulseEKKO Pro with 100 MHz antennas, and both 500 and 1000 V transmitting power. The 1000 V transmitter yielded greater subsurface reflection energy than for the 500 V transmitter, but the direct ground wave was “clipped”, i.e. the top of the radar wavelet was truncated. The clipped waveform adversely affects migration and deconvolution, because the waveform top has a sharp “corner” rather than a smooth wavecrest. In general, similar subsurface information can be obtained using more stacking of a lower power signal. The rapidly deployed GPR survey was useful in earthquake response and recovery. It partially revealed what practices were successful for treating land affected by fault rupture, providing peace of mind to farmers that land was safe for people and livestock It also provided an insight into how modern agriculture may modify transient geological disturbances in gravelly soils

Agricultural land rehabilitation following 2010 Darfield (Canterbury) earthquake: A preliminary report

This paper describes the nature of earthquake damage and rehabilitation of rural land affected by fault rupture and liquefaction following the 4 September 2010 Darfield (Canterbury) Earthquake. Remediation of land damaged by fault rupture and liquefaction was a significant concern for affected farmers and land-owners. A multidisciplinary team of researchers linked to the Rural Recovery Group (responsible for recovery of rural areas following the Canterbury earthquake) used a variety of techniques to assess land damage and evaluate the effectiveness of various rehabilitation techniques. It was found that land damage caused by strike slip fault rupture could generally be repaired by heavy roller. In areas of severe surface deformation and fracturing, deep cultivation followed by rolling was necessary to close surface fractures and flatten fault micro-topography to restore the land to a useable condition for agricultural use. Liquefaction damage to land consisted of blistered topography (by liquefied sediment injecting between topsoil and sub-soil) and liquefied sediment ejection at the surface. Both surfaces were often unsuitable for continuing agricultural operations. Several passes by a rotary-hoe and power-harrow effectively smoothed blisters and returned paddocks to a suitable state. Land severely affected by sediment ejection required scraping or grading of the sediment to < 50 mm and cultivation of the material into the topsoil. Both treatments resulted in destruction of current pasture or crop. Land less severely affected could be treated by spreading only, which conserved the existing pasture. Future work will track the on-going recovery of remediated and un-remediated land

The evolution of financial accounting in Portugal since the 1960s : a new institutional economics perspective

Using a new institutional economics perspective, this article analyses the economic and political context that led to accounting standardisation in Portugal from 1977 onwards and to the recent adoption of the International Financial Reporting Standards (IFRS). The process of accounting standardisation was related to the tax reform of 1963. Additionally, evidence was found that there were also political pressures related to the need to improve the national systems of accounts. The lack of development of the accounting profession and the emphasis on legality substantiated the need for enforcement in the law in 1977 of a standardised accounting plan that was similar to other plans in Europe, namely the French Plan. In a legalist country like Portugal, the modelling of national standards on the international ones and the definitive adoption of adapted IFRS in 2010 by unlisted companies had to be complemented by the enactment in law of the accounting regulations.Fundação para a Ciência e a Tecnologia (FCT