Neuronal expression of the ubiquitin ligase Nedd4-2 in rat dorsal root ganglia: Modulation in the spared nerve injury model of neuropathic pain.

Neuronal hyperexcitability following peripheral nerve lesions may stem from altered activity of voltage-gated sodium channels (VGSCs), which gives rise to allodynia or hyperalgesia. In vitro, the ubiquitin ligase Nedd4-2 is a negative regulator of VGSC α-subunits (Na(v)), in particular Na(v)1.7, a key actor in nociceptor excitability. We therefore studied Nedd4-2 in rat nociceptors, its co-expression with Na(v)1.7 and Na(v)1.8, and its regulation in pathology. Adult rats were submitted to the spared nerve injury (SNI) model of neuropathic pain or injected with complete Freund's adjuvant (CFA), a model of inflammatory pain. L4 dorsal root ganglia (DRG) were analyzed in sham-operated animals, seven days after SNI and 48h after CFA with immunofluorescence and Western blot. We observed Nedd4-2 expression in almost 50% of DRG neurons, mostly small and medium-sized. A preponderant localization is found in the non-peptidergic sub-population. Additionally, 55.7±2.7% and 55.0±3.6% of Nedd4-2-positive cells are co-labeled with Na(v)1.7 and Na(v)1.8 respectively. SNI significantly decreases the proportion of Nedd4-2-positive neurons from 45.9±1.9% to 33.5±0.7% (p<0.01) and the total Nedd4-2 protein to 44%±0.13% of its basal level (p<0.01, n=4 animals in each group, mean±SEM). In contrast, no change in Nedd4-2 was found after peripheral inflammation induced by CFA. These results indicate that Nedd4-2 is present in nociceptive neurons, is downregulated after peripheral nerve injury, and might therefore contribute to the dysregulation of Na(v)s involved in the hyperexcitability associated with peripheral nerve injuries.

Influence of the (111) twinning on the formation of diamond cubic/diamond hexagonal heterostructures in Cu-catalyzed Si nanowires

The occurrence of heterostructures of cubic silicon/hexagonal silicon as disks defined along the nanowire (111) growth direction is reviewed in detail for Si nanowires obtained using Cu as catalyst. Detailed measurements on the structural properties of both semiconductor phases and their interface are presented. We observe that during growth, lamellar twinning on the cubic phase along the (111) direction is generated. Consecutive presence of twins along the (111) growth direction was found to be correlated with the origin of the local formation of the hexagonal Si segments along the nanowires, which define quantum wells of hexagonal Si diamond. Finally, we evaluate and comment on the consequences of the twins and wurtzite in the final electronic properties of the wires with the help of the predicted energy band diagram.

Root system distribution of sugar cane as related to nitrogen fertilization, evaluated by two methods: monolith and probes

Few studies on sugar cane have evaluated the root system of the crop, in spite of its importance. This is mainly due to the difficulty of evaluation and high variability of results. The objective of this study was to develop an evaluation method of the cane root system by means of probes so as to evaluate the mass, distribution and metabolically active roots related to N fertilization at planting. For this purpose, an experiment was conducted in an Arenic Kandiustults with medium texture in Jaboticabal/SP, in a randomized block design with four replications and four treatments: control (without N) and 40, 80 and 120 kg ha-1 of N applied in the form of urea in the planting furrow of the cane variety SP81 3250. One week before harvest, a urea-15N solution was applied at the cane stalk base to detect active metabolism in the root system. Trenches of 1.5 m length and 0.6 m depth were opened between two sugar cane rows for root sampling by two methods: monoliths (0.3, 0.2 and 0.15 m wide, deep and long respectively) taken from the trench wall and by probe (internal diameter 0.055 m). For each method, 15 samples per plot were collected. The roots were separated from the soil in a sieve (2 mm mesh), oven-dried (at 65 ºC) and the dry matter was measured. Root sampling by probes resulted in root mass that did not differ from the evaluation in monoliths, indicating that this evaluation method may be used for sugar cane root mass, although neither the root distribution in the soil profile nor the rhizome mass were efficiently evaluated, due to the small sample volume. Nitrogen fertilization at planting did not result in a greater root accumulation in the sugar cane plant, but caused changes in the distribution of the root system in the soil. The absence of N fertilization led to a better root distribution in the soil profile, with 50, 34 and 16 % in the 0-0.2, 0.2-0.4 and 0.4-0.6 m layers, respectively; in the fertilized treatments the roots were concentrated in the surface layer, with on average 70, 17 and 13 % for the same layers. The metabolically active roots were concentrated in the center of the cane stool, amounting to 40 % of the total root mass, regardless of N fertilization (application of 120 kg ha-1 N or without N).

Phosphorus and root distribution and corn growth as related to long-term tillage systems and fertilizer placement

Soil and fertilizer management during cultivation can affect crop productivity and profitability. Long-term experiments are therefore necessary to determine the dynamics of nutrient and root distribution as related to soil profile, as well as the effects on nutrient uptake and crop growth. An 18-year experiment was conducted at the Federal University of Rio Grande do Sul State (UFRGS), in Eldorado do Sul, Brazil, on Rhodic Paleudult soil. Black oat and vetch were planted in the winter and corn in the summer. The soil management methods were conventional, involving no-tillage and strip tillage techniques and broadcast, row-and strip-applied fertilizer placement (triple superphosphate). Available P (Mehlich-1) and root distribution were determined in soil monoliths during the corn grain filling period. Corn shoot dry matter production and P accumulation during the 2006/2007 growing season were determined and the efficiency of P utilization calculated. Regardless of the degree of soil mobilization, P and roots were accumulated in the fertilized zone with time, mainly in the surface layer (0-10 cm). Root distribution followed P distribution for all tillage systems and fertilizer treatments. Under no-tillage, independent of the fertilizer placement, the corn plants developed more roots than in the other tillage systems. Although soil tillage systems and fertilizer treatments affected P and root distribution throughout the soil profile, as well as P absorption and corn growth, the efficiency of P utilization was not affected.

Influence of premetallization surface treatment on the formation of Schottky Au-nGaN contacts

The influence of premetallization surface preparation on the structural, chemical, and electrical properties of Au-nGaN interfaces has been investigated by x-ray photoemission spectroscopy (XPS), current-voltage measurement (I-V) and cross-section transmission electron microscopy (TEM). XPS analysis showed that the three GaN substrate treatments investigated i.e., ex situ hydrofluoric acid etch, in situ anneal in ultrahigh-vacuum (UHV), and in situ Ga reflux cleaning in UHV result in surfaces increasingly free of oxygen contamination. XPS and TEM characterization of Au-nGaN formed after the three premetallization surface treatments show that HF etching and UHV annealing produce abrupt, well-defined interfaces. Conversely, GaN substrate cleaning in a Ga flux results in Au/GaN intermixing. I-V characterization of Au¿nGaN contacts yields a Schottky barrier height of 1.25 eV with a very low-ideality factor and very good contact uniformity for the premetallization UHV anneal, while the Ga reflux cleaning results in a much lower barrier (0.85 eV), with poor ideality and uniformity. I-V and XPS results suggest a high density of acceptor states at the surface, which is further enhanced by UHV annealing. These results are discussed in the context of current models of Schottky barrier formation.

New evidence of the real interest rate parity for OECD countries using panel unit root tests with breaks

This paper tests for real interest parity (RIRP) among the nineteen major OECD countries over the period 1978:Q2-1998:Q4. The econometric methods applied consist of combining the use of several unit root or stationarity tests designed for panels valid under cross-section dependence and presence of multiple structural breaks. Our results strongly support the fulfilment of the weak version of the RIRP for the studied period once dependence and structural breaks are accounted for.

Reggies/flotillins regulate E-cadherin-mediated cell contact formation by affecting EGFR trafficking.

The reggie/flotillin proteins are implicated in membrane trafficking and, together with the cellular prion protein (PrP), in the recruitment of E-cadherin to cell contact sites. Here, we demonstrate that reggies, as well as PrP down-regulation, in epithelial A431 cells cause overlapping processes and abnormal formation of adherens junctions (AJs). This defect in cell adhesion results from reggie effects on Src tyrosine kinases and epidermal growth factor receptor (EGFR): loss of reggies reduces Src activation and EGFR phosphorylation at residues targeted by Src and c-cbl and leads to increased surface exposure of EGFR by blocking its internalization. The prolonged EGFR signaling at the plasma membrane enhances cell motility and macropinocytosis, by which junction-associated E-cadherin is internalized and recycled back to AJs. Accordingly, blockage of EGFR signaling or macropinocytosis in reggie-deficient cells restores normal AJ formation. Thus, by promoting EGFR internalization, reggies restrict the EGFR signaling involved in E-cadherin macropinocytosis and recycling and regulate AJ formation and dynamics and thereby cell adhesion.

In vitro evaluation of staphylococcus aureus biofilm formation on bone grafts and bone substitues

Background: Bacteria form a biofilm on the surface of orthopaedic devices, causing persistent and infection. Little is known about biofilms formation on bone grafts and bone substitutes. We analyzed various representative materials regarding their propensity for biofilm formation caused by Staphylococcus aureus.Methods: As bone graft beta-tricalciumphosphate (b-TCP, CyclOsTM) and as bone substitute a tantalum metal mesh (trabecular metalTM) and PMMA (Pala-cosTM) were investigated. As test organism S. aureus (strain ATCC 29213) was used. Test materials were incubated with bacterial solution of 105 colony-forming units (cfu)/ml at 37°C for 24 h without shaking. After 24 h, the test materials were removed and washed 3 times in normal saline, followed by sonication in 50 ml Ringer solution at 40 kHz for 5 minutes. The resulting sonication fluid was plated in aliquots of 0.1 ml onto aerobe blood agar with 5% sheep blood and incubated at 37°C with 5% CO2 for 24 h. Then, bacterial counts were enumerated and expressed as cfu/ml. All experiments were performed in triplicate to calculate the mean ± standard deviation. The Wilcoxon test was used for statistical calculations.Results: The three investigated materials show a differing specific surface with b-TCB>trabecular metal>PMMA per mm2. S. aureus formed biofilm on all test materials as confirmed by quantitative culture after washing and sonication. The bacterial counts in sonication fluid (in cfu/ml) were higher in b-TCP (5.1 x 106 ± 0.6 x 106) and trabecular metal (3.7 x 106 ± 0.6 x 106) than in PMMA (3.9 x 104 ± 1.8 x 104), p<0.05.Conclusion: Our results demonstrate that about 100-times more bacteria adhere on b-TCP and trabecular metal than on PMMA, reflecting the larger surface of b-TCP and trabecuar metal compared to the one of PMMA. This in-vitro data indicates that bone grafts are susceptible to infection. Further studies are needed to evaluate efficient approaches to prevent and treat infections associated with bone grafts and substitutes, including modification of the surface or antibacterial coating.

Effect of abscisic acid on maize root growth. A critical examination

The effect of abscisic acid (ABA) on the growth of maize roots maintained in the dark is investigated in relation to the root varieties and the root age, the mode of application, the concentration used and the duration of both the treatment and the culture. In all the assays, when ABA produces a significant change in root elongation, it shows an inhibitory effect which is enhanced with increasing ABA concentration. The data strongly support the hypothesis that ABA could be one of the growth inhibitors which are formed in or released from the root cap.

Bermuda grass sod production as related to nitrogen rates

Of all nutrients, N has the strongest effect on grass growth and an adequate N fertilization can reduce the time required for the formation of high-quality mats. This study aimed to evaluate the influence of N fertilization on Bermuda grass sod production and quality. The experiment was conducted in an area of commercial sod production, in Capela do Alto, state of São Paulo. Cynodon dactylon (Pers) L., known as Bermuda grass, was evaluated in a randomized complete block design with five treatments and four replications. Treatments consisted of five N rates: 0, 150, 300, 450 and 600 kg ha-1. Increasing N applications to Bermuda grass increased the soil cover rate, reducing the time required for mat formation. The accumulation of rhizome + root + stolon dry matter was highest at a rate of 354 kg ha-1 N and the mat resistance to breakage at a rate of 365 kg ha-1 N. Nitrogen rates between 354 and 365 kg ha-1 increased mat resistance and consequently the suitability for postharvest handling, tending to improve the efficiency in the area.

Level shifts in a panel data based unit root test : an application to the rate of unemployment

Several unit root tests in panel data have recently been proposed. The test developed by Harris and Tzavalis (1999 JoE) performs particularly well when the time dimension is moderate in relation to the cross-section dimension. However, in common with the traditional tests designed for the unidimensional case, it was found to perform poorly when there is a structural break in the time series under the alternative. Here we derive the asymptotic distribution of the test allowing for a shift in the mean, and assess the small sample performance. We apply this new test to show how the hypothesis of (perfect) hysteresis in Spanish unemployment is rejected in favour of the alternative of the natural unemployment rate, when the possibility of a change in the latter is considered.

La recherche en psychothérapie : impact sur la clinique et sur la formation

Jusqu'à aujourd'hui la recherche en psychothérapie a essentiellement exploré quatre questions clés : 1) la psychothérapie est-elle efficace?; 2) quelle forme de psychothérapie est la plus efficace ? ; 3) quelle forme de psychothérapie est efficace pour quel patient? et 4) qu'est-ce qui permet à la psychothérapie d'être efficace? Si l'efficacité de la psychothérapie est désormais reconnue, la recherche empirique n'a jamais permis de désigner une approche psychothérapeutique comme étant la plus efficace de toutes. Les questions de l'indication différentielle des formes de psychothérapie selon les pathologies, et celles concernant les processus de la thérapie, qui permettraient d'en prédire le résultat, n'ont pas trouvé à ce jour de réponse définitive.