Quantitative MRI of Vastus Medialis, Vastus Lateralis and Gluteus Medius Muscle Workload after Squat Exercise: Comparison Between Squatting with Hip Adduction and Hip Abduction

The aim of the present study was to evaluate the use MRI to quantify the workload of gluteus medius (GM), vastus medialis (VM) and vastus lateralis (VL) muscles in different types of squat exercises. Fourteen female volunteers were evaluated, average age of 22 +/- 2 years, sedentary, without clinical symptoms, and without history of previous lower limb injuries. Quantitative MRI was used to analyze VM, VL and GM muscles before and after squat exercise, squat associated with isometric hip adduction and squat associated with isometric hip abduction. Multi echo images were acquired to calculate the transversal relaxation times (T2) before and after exercise. Mixed Effects Model statistical analysis was used to compare images before and after the exercise (Delta T2) to normalize the variability between subjects. Imaging post processing was performed in Matlab software. GM muscle was the least active during the squat associated with isometric hip adduction and VM the least active during the squat associated with isometric hip abduction, while VL was the most active during squat associated with isometric hip adduction. Our data suggests that isometric hip adduction during the squat does not increase the workload of VM, but decreases the GM muscle workload. Squat associated with isometric hip abduction does not increase VL workload.

Valorisation of organic waste: new developments from proton nuclear magnetic resonance characterization

The last half-century has seen a continuing population and consumption growth, increasing the competition for land, water and energy. The solution can be found in the new sustainability theories, such as the industrial symbiosis and the zero waste objective. Reducing, reusing and recycling are challenges that the whole world have to consider. This is especially important for organic waste, whose reusing gives interesting results in terms of energy release. Before reusing, organic waste needs a deeper characterization. The non-destructive and non-invasive features of both Nuclear Magnetic Resonance (NMR) relaxometry and imaging (MRI) make them optimal candidates to reach such characterization. In this research, NMR techniques demonstrated to be innovative technologies, but an important work on the hardware and software of the NMR LAGIRN laboratory was initially done, creating new experimental procedures to analyse organic waste samples. The first results came from soil-organic matter interactions. Remediated soils properties were described in function of the organic carbon content, proving the importance of limiting the addition of further organic matter to not inhibit soil processes as nutrients transport. Moreover NMR relaxation times and the signal amplitude of a compost sample, over time, showed that the organic matter degradation of compost is a complex process that involves a number of degradation kinetics, as a function of the mix of waste. Local degradation processes were studied with enhanced quantitative relaxation technique that combines NMR and MRI. The development of this research has finally led to the study of waste before it becomes waste. Since a lot of food is lost when it is still edible, new NMR experiments studied the efficiency of conservation and valorisation processes: apple dehydration, meat preservation and bio-oils production. All these results proved the readiness of NMR for quality controls on a huge kind of organic residues and waste.

A practical approach for outdoors distributed target localization in wireless sensor networks

Wireless sensor networks are posed as the new communication paradigm where the use of small, low-complexity, and low-power devices is preferred over costly centralized systems. The spectra of potential applications of sensor networks is very wide, ranging from monitoring, surveillance, and localization, among others. Localization is a key application in sensor networks and the use of simple, efficient, and distributed algorithms is of paramount practical importance. Combining convex optimization tools with consensus algorithms we propose a distributed localization algorithm for scenarios where received signal strength indicator readings are used. We approach the localization problem by formulating an alternative problem that uses distance estimates locally computed at each node. The formulated problem is solved by a relaxed version using semidefinite relaxation technique. Conditions under which the relaxed problem yields to the same solution as the original problem are given and a distributed consensusbased implementation of the algorithm is proposed based on an augmented Lagrangian approach and primaldual decomposition methods. Although suboptimal, the proposed approach is very suitable for its implementation in real sensor networks, i.e., it is scalable, robust against node failures and requires only local communication among neighboring nodes. Simulation results show that running an additional local search around the found solution can yield performance close to the maximum likelihood estimate.

O LÚDICO VIA FÁBULAS EM ATENDIMENTO PSICOTERAPÊUTICO: UM ESTUDO DE CASO CLÍNICO DE MOBBING

Esta pesquisa verifica a validade da utilização de fábulas em processo psicoterapêutico de paciente de Mobbing acometida de depressão e síndrome de pânico. Desenvolve-se por meio de estudo de caso avaliativo-interventivo evolutivo prolongado, com um total de 116 sessões semanais. Inicialmente realiza o diagnóstico clínico elaborado a partir do desenho da figura humana, extraído do teste projetivo House Tree and Person, de entrevista inicial semi-dirigida, e de coleta de relatos verbais e observações feitas durante os primeiros atendimentos. As sessões são realizadas com utilização ocasional de fábulas, associada ou não a técnicas de relaxamento de Schultz e Jacobson, com interpretação de sonhos e recomendação de filmes. O objetivo é verificar se as fábulas contribuem de forma positiva para o paciente compreender com mais facilidade as interpretações do psicoterapeuta, se diminui sua resistência ao falar dos seus conteúdos e se amplia à consciência simbólica. O primeiro momento interventivo tem a duração de aproximadamente 16 meses, o segundo, de 04 meses, quando é solicitado o segundo desenho e o terceiro processa-se em 09 meses, quando é solicitado o último desenho. No primeiro momento é proporcionado à paciente um ambiente facilitador com sustentação emocional (Holding), buscando resgatar sua ilusão, numa visão winnicottiana. Revela-se uma situação de Mobbing acompanhada de depressão manifesta e síndrome do pânico; com alto nível de exigência pessoal e profissional; grande passividade nos relacionamentos e na dinâmica do casal. Ao final desse momento, já consegue começar a desviar sua auto-agressividade para o meio externo de maneira mais positiva e socialmente aceita. No segundo momento predomina o encontro e aceitação de seu verdadeiro jeito de ser; enxerga o quanto estava se deixando prejudicar; mostra-se mais confiante, comunica-se e enfrenta melhor suas dificuldades afetivas. No terceiro momento demonstra estar segura e feliz. Cuida de sua aparência e sente prazer em ser notada socialmente. Demonstra ter aprendido a se defender em situações de confronto, com maior autonomia e verbaliza estar muito feliz com as mudanças, sorri com freqüência. A análise evolutiva dos desenhos confirmam esta boa evolução. A utilização de fábulas foi muito bem aceita pela paciente, que conseguiu por meio da leitura simbólica contida nas mesmas, aproximar-se de sua problemática e aprender a lidar com ela de forma mais saudável. Os resultados também indicam que a utilização de relaxamento associado à leitura das fábulas contribuiu para sua assimilação mais abrangente e profunda. O estudo ilustra a evolução do caso por meio de 24 vinhetas, devidamente analisadas em relação aos momentos descritos.(AU)

O LÚDICO VIA FÁBULAS EM ATENDIMENTO PSICOTERAPÊUTICO: UM ESTUDO DE CASO CLÍNICO DE MOBBING

Esta pesquisa verifica a validade da utilização de fábulas em processo psicoterapêutico de paciente de Mobbing acometida de depressão e síndrome de pânico. Desenvolve-se por meio de estudo de caso avaliativo-interventivo evolutivo prolongado, com um total de 116 sessões semanais. Inicialmente realiza o diagnóstico clínico elaborado a partir do desenho da figura humana, extraído do teste projetivo House Tree and Person, de entrevista inicial semi-dirigida, e de coleta de relatos verbais e observações feitas durante os primeiros atendimentos. As sessões são realizadas com utilização ocasional de fábulas, associada ou não a técnicas de relaxamento de Schultz e Jacobson, com interpretação de sonhos e recomendação de filmes. O objetivo é verificar se as fábulas contribuem de forma positiva para o paciente compreender com mais facilidade as interpretações do psicoterapeuta, se diminui sua resistência ao falar dos seus conteúdos e se amplia à consciência simbólica. O primeiro momento interventivo tem a duração de aproximadamente 16 meses, o segundo, de 04 meses, quando é solicitado o segundo desenho e o terceiro processa-se em 09 meses, quando é solicitado o último desenho. No primeiro momento é proporcionado à paciente um ambiente facilitador com sustentação emocional (Holding), buscando resgatar sua ilusão, numa visão winnicottiana. Revela-se uma situação de Mobbing acompanhada de depressão manifesta e síndrome do pânico; com alto nível de exigência pessoal e profissional; grande passividade nos relacionamentos e na dinâmica do casal. Ao final desse momento, já consegue começar a desviar sua auto-agressividade para o meio externo de maneira mais positiva e socialmente aceita. No segundo momento predomina o encontro e aceitação de seu verdadeiro jeito de ser; enxerga o quanto estava se deixando prejudicar; mostra-se mais confiante, comunica-se e enfrenta melhor suas dificuldades afetivas. No terceiro momento demonstra estar segura e feliz. Cuida de sua aparência e sente prazer em ser notada socialmente. Demonstra ter aprendido a se defender em situações de confronto, com maior autonomia e verbaliza estar muito feliz com as mudanças, sorri com freqüência. A análise evolutiva dos desenhos confirmam esta boa evolução. A utilização de fábulas foi muito bem aceita pela paciente, que conseguiu por meio da leitura simbólica contida nas mesmas, aproximar-se de sua problemática e aprender a lidar com ela de forma mais saudável. Os resultados também indicam que a utilização de relaxamento associado à leitura das fábulas contribuiu para sua assimilação mais abrangente e profunda. O estudo ilustra a evolução do caso por meio de 24 vinhetas, devidamente analisadas em relação aos momentos descritos.(AU)

O LÚDICO VIA FÁBULAS EM ATENDIMENTO PSICOTERAPÊUTICO: UM ESTUDO DE CASO CLÍNICO DE MOBBING

Esta pesquisa verifica a validade da utilização de fábulas em processo psicoterapêutico de paciente de Mobbing acometida de depressão e síndrome de pânico. Desenvolve-se por meio de estudo de caso avaliativo-interventivo evolutivo prolongado, com um total de 116 sessões semanais. Inicialmente realiza o diagnóstico clínico elaborado a partir do desenho da figura humana, extraído do teste projetivo House Tree and Person, de entrevista inicial semi-dirigida, e de coleta de relatos verbais e observações feitas durante os primeiros atendimentos. As sessões são realizadas com utilização ocasional de fábulas, associada ou não a técnicas de relaxamento de Schultz e Jacobson, com interpretação de sonhos e recomendação de filmes. O objetivo é verificar se as fábulas contribuem de forma positiva para o paciente compreender com mais facilidade as interpretações do psicoterapeuta, se diminui sua resistência ao falar dos seus conteúdos e se amplia à consciência simbólica. O primeiro momento interventivo tem a duração de aproximadamente 16 meses, o segundo, de 04 meses, quando é solicitado o segundo desenho e o terceiro processa-se em 09 meses, quando é solicitado o último desenho. No primeiro momento é proporcionado à paciente um ambiente facilitador com sustentação emocional (Holding), buscando resgatar sua ilusão, numa visão winnicottiana. Revela-se uma situação de Mobbing acompanhada de depressão manifesta e síndrome do pânico; com alto nível de exigência pessoal e profissional; grande passividade nos relacionamentos e na dinâmica do casal. Ao final desse momento, já consegue começar a desviar sua auto-agressividade para o meio externo de maneira mais positiva e socialmente aceita. No segundo momento predomina o encontro e aceitação de seu verdadeiro jeito de ser; enxerga o quanto estava se deixando prejudicar; mostra-se mais confiante, comunica-se e enfrenta melhor suas dificuldades afetivas. No terceiro momento demonstra estar segura e feliz. Cuida de sua aparência e sente prazer em ser notada socialmente. Demonstra ter aprendido a se defender em situações de confronto, com maior autonomia e verbaliza estar muito feliz com as mudanças, sorri com freqüência. A análise evolutiva dos desenhos confirmam esta boa evolução. A utilização de fábulas foi muito bem aceita pela paciente, que conseguiu por meio da leitura simbólica contida nas mesmas, aproximar-se de sua problemática e aprender a lidar com ela de forma mais saudável. Os resultados também indicam que a utilização de relaxamento associado à leitura das fábulas contribuiu para sua assimilação mais abrangente e profunda. O estudo ilustra a evolução do caso por meio de 24 vinhetas, devidamente analisadas em relação aos momentos descritos.(AU)

Source/receptor reconciliation of ambient organic fine particulate matter in Palm Beach County

Airborne particulate matter (PM) is of environmental concern not only in urban but also rural areas that are easily inhalable and have been considered responsible, together with gaseous pollutants, for possible health effects. The objectives of this research study is to generate an extensive data set for ambient PM collected at Belle Glade and Delray Beach that ultimately was used together with published source profiles to predict the contributions of major sources to the overall airborne particle burden in Belle Glade and Delray Beach. ^ The size segregated particle sampling was conducted for one entire year. The samples collected during the months of January and May were further subjected to chemical analysis for organic compounds by Gas Chromatography-Mass Spectrometry. Additional, PM10 sampling was conducted simultaneously with size segregated particle sampling during January and May to analyze for trace elements using Instrumental Neutron Activation Analysis technique. Elements and organic marker compounds were used in Chemical Mass Balance modeling to determine the major source contribution to the ambient fine particle matter burden. ^ Size segregated particle distribution results show bimodal in both sampling sites. Sugarcane pre-harvest burning in the rural site elevated PM10 concentration by about 30% during the sugarcane harvest season compared to sugarcane growing season. Sea salt particles and Saharan dust particles accounted for the external sources. ^ The results of trace element analysis show that Al, Ca, Cs, Eu, Lu, Nd, Sc, Sm, Th, and Yb are more abundant at the rural sampling site. The trace elements Ba, Br, Ce, Cl, Cr, Fe, Gd, Hf, Na, Sb, Ta, V, and W show high abundance at the urban site due to anthropogenic activities except for Na and Cl, which are from sea salt spray. On the other hand, size segregated trace organic compounds measurements show that organic compounds mainly from combustion process were accumulated in PM0.95. ^ In conclusion, major particle sources were determined by the CMB8.2 software as follows: road dust, sugarcane leaf burning, diesel-powered and gasoline powered vehicle exhaust, leaf surface abrasion particles, and a very small fraction of meat cooking. ^

Topology Optimization of continuum structures with epsilon-relaxed stress constraints

Topology optimization of linear elastic continuum structures is a challenging problem when considering local stress constraints. The reasons are the singular behavior of the constraint with the density design variables, combined with the large number of constraints even for small finite element meshes. This work presents an alternative formulation for the s-relaxation technique, which provides an workaround for the singularity of the stress constraint. It also presents a new global stress constraint formulation. Derivation of the sensitivities for the constraint by the adjoint method is shown. Results for single and multiple load cases show the potential of the new formulation.

Pflegerische Versorgungskonzepte für Personen mit Demenzerkrankungen

Einleitung: In Deutschland leiden derzeit etwa eine Million Menschen an einer Demenzerkrankung. Aufgrund der demografischen Entwicklung ist mit einem deutlichen Anstieg der Häufigkeit solcher Erkrankungen in den kommenden Jahren zu rechnen. Demenz ist in höherem Alter die häufigste Ursache von Pflegebedürftigkeit. Da diese Krankheiten in der Regel nicht heilbar sind, liegt der Fokus der Pflege auf der Verzögerung des Voranschreitens der Erkrankung sowie der Aufrechterhaltung von Funktionsfähigkeit und Lebensqualität der Betroffenen. Fragestellung: Wie ist die Evidenz für pflegerische Konzepte für Patienten mit Demenz hinsichtlich gebräuchlicher Endpunkte wie kognitive Funktionsfähigkeit, Fähigkeit zur Durchführung von Aktivitäten des täglichen Lebens, Lebensqualität, Sozialverhalten? Wie ist die Kosten-Effektivität der betrachteten Pflegekonzepte zu bewerten? Welche ethischen, sozialen oder juristischen Aspekte werden in diesem Kontext diskutiert? Methoden: Auf Basis einer systematischen Literaturrecherche werden randomisierte kontrollierte Studien (RCT) mit mindestens 30 Teilnehmern zu folgenden Pflegekonzepten eingeschlossen: Validation/emotionsorientierte Pflege, Ergotherapie, sensorische Stimulation, Entspannungsverfahren, Realitätsorientierung und Reminiszenz. Die Studien müssen ab 1997 (für den ökonomischen Teil ab 1990) in deutscher oder englischer Sprache publiziert worden sein. Ergebnisse: Insgesamt 20 Studien erfüllen die Einschlusskriterien. Davon befassen sich drei Studien mit der Validation/emotionsorientierte Pflege, fünf Studien mit der Ergotherapie, sieben Studien mit verschiedenen Varianten sensorischer Stimulation, je zwei Studien mit der Realitätsorientierung und der Reminiszenz und eine Studie mit einem Entspannungsverfahren. Keine signifikanten Unterschiede zwischen Interventions- und Kontrollgruppe berichten zwei von drei Studien zur Validation/emotionsorientierten Pflege, zwei von fünf Studien zur Ergotherapie, drei von sieben Studien zur sensorischen Stimulation, beide Studien zur Reminiszenz, und die Studie zur Entspannung. Von den verbleibenden zehn Studien berichten sieben teilweise positive Ergebnisse zugunsten der Intervention und drei Studien (Ergotherapie, Aromatherapie, Musik/Massage) berichten positive Effekte der Intervention hinsichtlich aller erhobenen Zielkriterien. Sechs Publikationen berichten ökonomische Ergebnisse von Pflegemaßnahmen. Eine Studie berichtet Zusatzkosten von 16 GBP (24,03 Euro (2006)) pro Patient pro Woche für Beschäftigungstherapie. Zwei weitere Veröffentlichungen geben inkrementelle Kosten von 24,30 USD (25,62 Euro (2006)) pro gewonnenen Mini-mental-state-examination-(MMSE)-Punkt pro Monat bzw. 1.380.000 ITL (506,21 Euro (2006)) pro gewonnenen MMSE-Punkt an. Zwei Publikationen berichten über Mischinterventionen, wobei einmal die Zusatzkosten für ein Aktivitätsprogramm (1,13 USD (1,39 Euro (2006)) pro Tag pro Pflegebedürftigem) und einmal der zeitliche Mehraufwand für die Betreuung mobiler Demenzpatienten (durchschnittlich 45 Minuten zusätzliche Pflegezeit pro Tag) berichtet wird. Hinsichtlich ethisch-sozialer Aspekte wird vor allem die Selbstbestimmung von Demenzpatienten diskutiert. Aus einer Demenzdiagnose lässt sich danach nicht zwingend schließen, dass die Betroffenen nicht eigenständig über eine Studienteilnahme entscheiden können. Im juristischen Bereich versucht die Regierung mit dem Pflege-Weiterentwicklungsgesetz (PfWG) die finanzielle Lage und die Betreuung der Pflegenden und Gepflegten zu verbessern. Weitere Fragestellungen rechtlicher Natur betreffen die Geschäftsfähigkeit bzw. die rechtliche Vertretung sowie die Deliktfähigkeit von an Demenz erkrankten Personen. Diskussion: Es gibt nur wenige methodisch angemessene Studien zu den in diesem Bericht berücksichtigten pflegerischen Konzepten für Demenzkranke. Die Studien haben überwiegend kleine Fallzahlen, und weisen erhebliche methodische Unterschiede hinsichtlich der Einschlusskriterien, der Durchführung, und der erfassten Zielkriterien auf. Diese Heterogenität zeigt sich auch in den Ergebnissen: in der Hälfte der eingeschlossen Studien gibt es keine positiven Effekte der Intervention im Vergleich zur Kontrollgruppe. Die andere Hälfte der Studien berichtet zum Teil positive Effekte bezüglicher unterschiedlicher Zielkriterien. Die ökonomischen Studien sind methodisch und thematisch nicht dazu geeignet die aufgeworfenen Fragestellungen zu beantworten. Ethische, soziale und juristische Aspekte werden diskutiert, aber nicht systematisch im Rahmen von Studien erfasst. Schlussfolgerung: Basierend auf der derzeitigen Studienlage liegt für keines der untersuchten Pflegekonzepte ausreichende Evidenz vor. Fehlende Evdienz bedeutet in diesem Kontext jedoch nicht zwingend fehlende Wirksamkeit. Vielmehr sind weitere Studien zu diesem Thema notwendig. Wünschenswert wären insbesondere Studien, die in Deutschland unter den Rahmenbedingungen des hiesigen Ausbildungs- und Pflegesystems durchgeführt werden. Dies gilt auch für die gesundheitsökonomische Bewertung der Pflege

Crystallization Kinetics and Electrical Relaxation of BaO-0.5Li(2)O-4.5B(2)O(3) Glasses

Transparent glasses in the composition BaO-0.5Li(2)O-4.5B(2)O(3) (BLBO) were fabricated via the conventional melt-quenching technique. X-ray powder diffraction combined with differential scanning calorimetric (DSC) studies carried out on the as-quenched samples confirmed their amorphous and glassy nature, respectively. The crystallization behavior of these glasses has been studied by isothermal and nonisothermal methods using DSC. Crystallization kinetic parameters were evaluated from the Johnson-Mehl-Avrami equation. The value of the Avrami exponent (n) was found to be 3.6 +/- 0.1, suggesting that the process involves three-dimensional bulk crystallization. The average value of activation energy associated with the crystallization of BLBO glasses was 317 +/- 10 kJ/mol. Transparent glass-ceramics were fabricated by controlled heat-treatment of the as-quenched glasses at 845 K/40 min. The dielectric constants for BLBO glasses and glass-ceramics in the 100 Hz-10 MHz frequency range were measured as a function of the temperature (300-925 K). The electrical relaxation and dc conductivity characteristics were rationalized using electric modulus formalism. The imaginary part of the electric modulus spectra was modeled using an approximate solution of the Kohlrausch-Williams-Watts relation. The temperature-dependent behavior of stretched exponent (beta) was discussed for the as-quenched and heat-treated BLBO glasses.

A deep‐level spectroscopic technique for determining capture cross‐section activation energy of Si‐related DX centers in AlxGa1-xAs

A deep‐level transient spectroscopy (DLTS) technique is reported for determining the capture cross‐section activation energy directly. Conventionally, the capture activation energy is obtained from the temperature dependence of the capture cross section. Capture cross‐section measurement is often very doubtful due to many intrinsic errors and is more critical for nonexponential capture kinetics. The essence of this technique is to use an emission pulse to allow the defects to emit electrons and the transient signal from capture process due to a large capture barrier was analyzed, in contrast with the emission signal in conventional DLTS. This technique has been applied for determining the capture barrier for silicon‐related DX centers in AlxGa1−xAs for different AlAs mole fractions.

Dielectric relaxation and anti-ferromagnetic coupling of BiEu03 and BiGd03

BiEuO3 (BE) and BiGdO3 (BG) are synthesized by the solid-state reaction technique. Rietveld refinement of the X-ray diffraction data shows that the samples are crystallized in cubic phase at room temperature having Fm3m symmetry with the lattice parameters of 5.4925(2) and 5.4712(2) A for BE and BG, respectively. Raman spectra of the samples are investigated to obtain the phonon modes of the samples. The dielectric properties of the samples are investigated in the frequency range from 42 Hz to 1.1 MHz and in the temperature range from 303 K to 673 K. An analysis of the real and imaginary parts of impedance is performed assuming a distribution of relaxation times as confirmed by the Cole-Cole plots. The frequency-dependent maxima in the loss tangent are found to obey an Arrhenius law with activation energy similar to 1 eV for both the samples. The frequency-dependent electrical data are also analyzed in the framework of conductivity formalism. Magnetization of the samples are measured under the field cooled (EC) and zero field cooled (ZFC) modes in the temperature range from 5 K to 300 K applying a magnetic Field of 500 Oe. The FC and ZFC susceptibilities show that BE is a Van Vleck paramagnetic material with antiferromagnetic coupling at low temperature whereas BG is an anti-ferromagnetic system. The results are substantiated by the M-11 loops of the materials taken at 5 K in the ZFC mode. (C) 2014 Elsevier B.V. All rights reserved

Carrier relaxation and thermal activation of localized excitons in self-organized InAs multilayers grown on GaAs substrates

We have investigated the temperature dependence of photoluminescence (PL) properties of a number of self-organized InAs/GaAs heterostructures with InAs layer thickness ranging from 0.5 to 3 ML. The temperature dependence of InAs exciton emission and linewidth was found to display a significant difference when the InAs layer thickness is smaller or larger than the critical thickness around 1.7 ML. The fast redshift of PL energy and an anomalous decrease of linewidth with increasing temperature were observed and attributed to the efficient relaxation process of carriers in multilayer samples, resulting from the spread and penetration of the carrier wave functions in coupled InAs quantum dots. The measured thermal activation energies of different samples demonstrated that the InAs wetting layer may act as a barrier for the thermionic emission of carriers in high-quality InAs multilayers, while in InAs monolayers and submonolayers the carriers are required to overcome the GaAs barrier to escape thermally from the localized states.

The Gastrointestinal Peptide Obestatin Induces Vascular Relaxation Via Specific Activation of Endothelium-Dependent Nitric Oxide Signalling.

Background and purpose: Obestatin is a recently-discovered gastrointestinal peptide with established metabolic actions, which is linked to diabetes and may exert cardiovascular benefits. Here we aimed to investigate the specific effects of obestatin on vascular relaxation. Experimental approach: Cumulative relaxation responses to obestatin peptides were assessed in isolated rat aorta and mesenteric artery (n=8) in the presence/absence of selective inhibitors. Complementary studies were performed in cultured bovine aortic endothelial cells (BAEC). Key results: Obestatin peptides elicited concentration-dependent relaxation in both aorta and mesenteric artery. Responses to full-length obestatin(1-23) were greater than those to obestatin(1-10) and obestatin(11-23). Obestatin(1-23)-induced relaxation was attenuated by endothelial denudation, L-NAME (NO synthase inhibitor), high extracellular K(+) , GDP-ß-S (G protein inhibitor), MDL-12,330A (adenylate cyclase inhibitor), wortmannin (PI3K inhibitor), KN-93 (CaMKII inhibitor), ODQ (guanylate cyclase inhibitor) and iberiotoxin (BK(Ca) blocker), suggesting that it is mediated by an endothelium-dependent NO signalling cascade involving an adenylate cyclase-linked G protein-coupled receptor, PI3K/Akt, Ca(2+) -dependent eNOS activation, soluble guanylate cyclase and modulation of vascular smooth muscle K(+) . Supporting data from BAEC indicated that nitrite production, intracellular Ca(2+) and Akt phosphorylation were increased after exposure to obestatin(1-23). Relaxations to obestatin(1-23) were unaltered by inhibitors of candidate endothelium-derived hyperpolarising factors (EDHFs) and combined SK(Ca) /IK(Ca) blockade, suggesting that EDHF-mediated pathways were not involved. Conclusions and Implications: Obestatin produces significant vascular relaxation via specific activation of endothelium-dependent NO signalling. These actions may be important in normal regulation of vascular function and are clearly relevant to diabetes, a condition characterised by endothelial dysfunction and cardiovascular complications.

Thermal annealing-induced electric dipole relaxation in natural alexandrite

Electrical properties of natural alexandrite (BeAl2O4:Cr3+) are investigated by the thermally stimulated depolarization current (TSDC) technique. Samples are submitted to consecutive annealing processes and TSDC is carried out after each annealing, yielding bands with different parameters. These bands are fitted by a continuous distribution of relaxation parameters: activation energy and pre-exponential factor of the Arrhenius equation. It has been observed that annealing influences the dipole relaxation behavior, since it promotes a modification of Fe3+ and C3+ impurity distributions on sites of distinct symmetry: Al-1 and Al-2. In order to have a reference for comparison, TSDC is also carried out on a synthetic alexandrite sample, where the only impurity present is Cr3+ ion.