Dibucaine effects on structural and elastic properties of lipid bilayers

In this work we report the interaction effects of the local anesthetic dibucaine (DBC) with lipid patches in model membranes by Atomic Force Microscopy (AFM). Supported lipid bilayers (egg phosphatidylcholine, EPC and dimyristoylphosphatidylcholine, DMPQ were prepared by fusion of unilamellar vesicles on mica and imaged in aqueous media. The AFM images show irregularly distributed and sized EPC patches on mica. On the other hand DMPC formation presents extensive bilayer regions on top of which multibilayer patches are formed. In the presence of DBC we observed a progressive disruption of these patches, but for DMPC bilayers this process occurred more slowly than for EPC. In both cases, phase images show the formation of small structures on the bilayer surface suggesting an effect on the elastic properties of the bilayers when DBC is present. Dynamic surface tension and dilatational surface elasticity measurements of EPC and DMPC monolayers in the presence of DBC by the pendant drop technique were also performed, in order to elucidate these results. The curve of lipid monolayer elasticity versus DBC concentration, for both EPC and DMPC cases, shows a maximum for the surface elasticity modulus at the same concentration where we observed the disruption of the bilayer by AFM. Our results suggest that changes in the local curvature of the bilayer induced by DBC could explain the anesthetic action in membranes. (C) 2008 Elsevier B.V. All rights reserved.

Dermaseptins from Phyllomedusa oreades and Phyllomedusa distincta: Liposomes fusion and/or lysis investigated by fluorescence and atomic force microscopy

Three dermaseptins, DS 01, DD K, and DD L, were compared with respect to their structural features and interactions with liposomes. Circular dichroic spectra at alcohols of different chain lengths revealed that DS 01 has the higher helicogenic potential in hydrophobic media. Binding of DS 01, DD K, and DD L to liposomes induced significant blue shifts of the emission spectra of the single tryptophan located at position 3 of all sequences indicating association of the peptides with bilayers. Kinetics evaluation of atomic force microscopy images evidenced the strong fusogenic activity of DS 01 whereas DD K and DD L showed increased lytic activities. (C) 2007 Elsevier Inc. All rights reserved.

Formation Of The Maritime Labor Force In Brazil: Culture And Daily Life, Tradition And Resistance (1808-1850).

Formation Of The Maritime Labor Force In Brazil: Culture And Daily Life, Tradition And Resistance (1808-1850). Since the 16(th) Century, Brazil has played a major role in the rise of a new economical and social order, in which ships represented a space of struggle and contradictions among rulers, captains and sailors. This article will study the proletarization process that transformed Indians, small farmers, free and slave black people in maritime labor force in Brazil during the first half of 19(th) century.

Premovement activity of the pre-supplementary motor area and the readiness for action: Studies of time-resolved event-related functional MRI

The supplementary motor area (SMA) is thought to play in important role in the preparation and organisation of voluntary movement. It has long been known that cortical activity begins to increase up to 2 s prior to voluntary self-initiated movement. This increasing premovement activity measured in EEG is known as the Bereitschaftspotential or readiness potential. Modern functional brain imaging methods, using event-related and time-resolved functional MRI techniques, are beginning to reveal the role of the SMA, and in particular the more anterior pre-SMA, in premovement activity associated with the readiness for action. In this paper we review recent studies using event-related time-resolved fMRI methods to examine the time-course of activation changes within the SMA throughout the preparation, readiness and execution of action. These studies suggest that the preSMA plays a common role in encoding or representing actions prior to our own voluntary self-initiated movements, during motor imagery, and from the observation of others' actions. We suggest that the pre-SMA generates and encodes motor representations which are then maintained in readiness for action. (c) 2005 Elsevier B.V. All rights reserved.

Age and gender influence on maximal bite force and masticatory muscles thickness

The present study aimed investigate the age and gender influence on maximal molar bite force and at outlining the criteria for normal masticatory muscle development in a sample of 177 Brazilian Caucasian dentate individuals aged 7-80 years divided into five age groups: I(7-12 years), II (13-20 years), III (21-40 years), IV (41-60 years), and V (61-80 years). Except for Group V, which comprised nine women and eight men, all groups were equally divided in respect to gender (20 M/20 F). Bite force was recorded with a mouth-adapted 1000 N dynamometer and the highest out of three records was regarded as the maximal bite force. The data were submitted to multivariate statistical analysis (SPSS 17.0 p < 0.05). Effects of group and gender were found, but no interactions between them. The ANOVA showed significant differences between groups bilaterally. Bonferroni`s test showed that group I had significantly lower bite force means at both sides as compared to all groups, except group V. No differences were found between the left and right sides. In all the groups, gender was found to be a significant factor associated with maximal bite force. A global comparison including all the subjects and measures showed that the means of men were approximately 30% higher than those of women, within-group comparisons yielded similar results in all groups. Muscle thickness was measured with a SonoSite Titan ultrasound tool using a high-resolution real-time 56 mm/10 MHz linear-array transducer. Three ultrasound images were obtained from the bilateral masseter and temporal muscles at rest and at maximal voluntary contraction. The means of the three measures in each clinical condition were analyzed with multivariate statistical analysis (SPSS 17.0 p < 0.05). A gradual increase in thickness of the masseter and temporal muscles was found both at rest and maximal voluntary contraction for groups I to IV, whereas a decrease in muscle thickness was observed in group V. Multivariate analysis showed that in both conditions there was an effect of group and gender. The study of the development of the stomatognathic system in relation to age and gender can provide useful data for the identification of normal and impaired functioning patterns. The results of this study indicate that age and gender are associated with structural and functional alterations in the muscles of the stomatognathic system. (C) 2010 Elsevier Ltd. All rights reserved.

Evaluation of molar and incisor bite force in indigenous compared with white population in Brazil

The purpose of this study was to deter-mine maximum bite force in molar and incisor regions in young Brazilian indigenous individuals, who have had a natural diet since birth, and compare the sample with white Brazilian individuals. To do this, individuals were paired one-to-one (same weight, height, and Class I facial pattern). A secondary purpose was to elucidate the relation between bite force and gender in both populations. Eighty-two Brazilians took part in this study. Participants were aged between 18 and 28 years and were divided into two groups: 41 Xingu indigenous individuals and 41 white Brazilian individuals, with 28 men and 13 women in each group. The inclusion criteria were: having complete dentition; normal occlusion; no neurological, psychiatric or movement disorders.; no reports of toothaches; having satisfactory periodontal health; absence of large facial skeletal alterations (typical Class II and Class III individuals); and no previous treatments using occlusal splints. To measure maximum bite force, a digital dynamometer model IDDK (Kratos-Equipamentos Industriais Ltda, Cotia, Sao Paulo, Brazil) was used, with a capacity of 1000 N, adapted for oral conditions. Assessments were made in the first molar (right and left) and central incisive regions. Results reveal that mean maximum bite forces in indigenous individuals of the right molar is 421 N, left molar 429 N and incisor region is 194 14 and for white individuals of the right molar is 410 N, left molar 422 N and incisor region is 117 N. Comparing indigenous with white individuals, maximal bite force showed a tendency of being greater in the indigenous group. It was observed that the incisor region showed statistical significance (p < 0.0005) but no significance was observed in the molar region. Moreover, indigenous men showed the highest bite force values. (C) 2007 Elsevier Ltd. All rights reserved.

The melatonin action on stromal stem cells within pericryptal area in colon cancer model under constant light

Constant light (LL) is associated with high incidence of colon cancer. MLT supplementation was related to the significant control of preneoplastic patterns. We sought to analyze preneoplastic patterns in colon tissue from animals exposed to LL environment (14 days; 300 lx), MLT-supplementation (10 mg/kg/day) and DMH-treatment (1,2 dimethylhydrazine; 125 mg/kg). Rodents were sacrificed and MLT serum levels were measured by radioimmunoassay. Our results indicated that LL induced ACF development (p < 0.001) with a great potential to increase the number of CD133(+) and CD68(+) cells (p < 0.05 and p < 0.001). LL also increased the proliferative process (PCNA-Li; p < 0.001) as well as decreased caspase-3 protein (p < 0.001), related to higher COX-2 protein expression (p < 0.001) within pericryptal colonic stroma (PCCS). However, MLT-supplementation controlled the development of dysplastic ACF (p < 0.001) diminishing preneoplastic patterns into PCCS as CD133 and CD68 (p < 0.05 and p < 0.001). These events were relative to decreased PCNA-Li index and higher expression of caspase-3 protein. Thus, MLT showed a great potential to control the preneoplastic patterns induced by LL. (C) 2011 Elsevier Inc. All rights reserved.

A possible mechanism of low molecular weight protein tyrosine phosphatase (LMW-PTP) activity modulation by glutathione action during human osteoblast differentiation

Objective: Low molecular weight protein tyrosine phosphatases (LMW-PTPs) are a family of enzymes strongly involved in the regulation of cell growth and differentiation. Since there is no information concerning the relationship between osteoblastic differentiation and LMW-PTP expression/activity, we investigated its involvement during human osteoblast-like cells (hFOB 1.19) differentiation. It is known that LMW-PTP is regulated by an elegant redox mechanism, so we also observed how the osteoblastic differentiation affected the reduced glutathione levels. Design: hFOB 1.19 cells were cultured in DMEM/F12 up to 35 days. The osteoblast phenotype acquisition was monitored by measuring alkaline phosphatase activity and mineralized nodule formation by Von Kossa staining. LMW-PTP activity and expression were measured using the p-nitrophenylphosphate as substrate and Western blotting respectively. Crystal violet assay determined the cell number in each experimental point. Glutathione level was determined by both HPLC and DNTB assays. Results: LMW-PTP modulation was coincident with the osteoblastic differentiation biomarkers, such as alkaline phosphatase activity and presence of nodules of mineralization in Vitro. Likewise LMW-PTP, the reduced glutathione-dependent microenvironment was modulated during osteoblastic differentiation. During this process, LMW-PTP expression/activity, as well as alkaline phosphatase and glutathione increased progressively up to the 21st day (p < 0.001) of culturing, decreasing thereafter. Conclusions: Our results clearly suggest that LMW-PTP expression/activity was rigorously modulated during osteoblastic differentiation, possibly in response to the redox status of the cells, since it seems to depend on suitable levels of reduced glutathione. in this way, we pointed out LMW-PTP as an important signaling molecule in osteoblast biology and bone formation. (C) 2009 Elsevier Ltd. All rights reserved.

Design, modelling and analysis of a six component force balance for hypervelocity wind tunnel testing

A combination of modelling and analysis techniques was used to design a six component force balance. The balance was designed specifically for the measurement of impulsive aerodynamic forces and moments characteristic of hypervelocity shock tunnel testing using the stress wave force measurement technique. Aerodynamic modelling was used to estimate the magnitude and distribution of forces and finite element modelling to determine the mechanical response of proposed balance designs. Simulation of balance performance was based on aerodynamic loads and mechanical responses using convolution techniques. Deconvolution was then used to assess balance performance and to guide further design modifications leading to the final balance design. (C) 2001 Elsevier Science Ltd. All rights reserved.

Globalisation and sustainability: environmental Kuznets curve and the WTO

Economic globalisation is seen by many as a driving force for global economic growth. Yet opinion is divided about the benefits of this process, as highlighted by the WTO meeting in Seattle in late 1999. Proponents of economic globalisation view it as a positive force for environmental improvement and as a major factor increasing the likelihood of sustainable development through its likely boost to global investment. These proponents mostly appeal to analysis based on the environmental Kuznets curve (EKC) to support their views about environmental improvement. But EKC-analysis has significant deficiencies. Furthermore, it is impossible to be confident that the process of economic globalisation will result in sustainable development, if 'weak conditions' only are satisfied. 'Strong conditions' probably need to be satisfied to achieve sustainable development, and given current global institutional arrangements, these are likely to be violated by the economic globalisation process. Global political action seems to be needed-to avert a deterioration in the global environment and to prevent unsustainability of development. This exposition demonstrates the limitations of EKC-analysis, identifies positive and negative effects of economic globalisation on pollution levels, and highlights connections between globalisation and the debate about whether strong or weak conditions are required for sustainable development. The article concludes with a short discussion of the position of WTO in relation to trade and the environment and the seemingly de facto endorsement of WTO of weak conditions for sustainable development. It suggests that WTO's relative neglect of environmental concerns is no longer politically tenable and needs to be reassessed in the light of recent developments in economic analysis. The skew of economic growth, e.g. in favour of developing countries, is shown to be extremely important from a global environmental perspective. (C) 2001 Elsevier Science B.V. All rights reserved.

Repeatability of maximal voluntary force and of surface EMG variables during voluntary isometric contraction of quadriceps muscles in healthy subjects

The repeatability of initial values and rate of change of EMG signal mean spectral frequency (MNF), average rectified values (ARV), muscle fiber conduction velocity (CV) and maximal voluntary contraction (MVC) was investigated in the vastus medialis obliquus (VMO) and vastus lateralis (VL) muscles of both legs of nine healthy male subjects during voluntary, isometric contractions sustained for 50 s at 50% MVC. The values of MVC were recorded for both legs three times on each day and for three subsequent days, while the EMG signals have been recorded twice a day for three subsequent days. The degree of repeatability was investigated using the Fisher test based upon the ANalysis Of VAriance (ANOVA), the Standard Error of the Mean (SEM) and the Intraclass Correlation Coefficient (ICC). Data collected showed a high level of repeatability of MVC measurement (normalized SEM from 1.1% to 6.4% of the mean). MNF and ARV initial values also showed a high level of repeatability (ICC > 70% for all muscles and legs except right VMO). At 50% MVC level no relevant pattern of fatigue was observed for the VMO and VL muscles, suggesting that other portions of the quadriceps might have contributed to the generated effort. These observations seem to suggest that in the investigation of muscles belonging to a multi-muscular group at submaximal level, the more selective electrically elicited contractions should be preferred to voluntary contractions. (C) 2001 Elsevier Science Ltd. All rights reserved.

An action research report on the Korean national digital library

This paper presents the results of my action research. I was involved in establishing and running a digital library that was founded by the government of South Korea. The process involved understanding the relationship between the national IT infrastructure and the success factors of the digital library. In building, the national IT infrastructure, a digital library system was implemented; it combines all existing digitized university libraries and can provide overseas information, such as foreign journal articles, instantly and freely to every Korean researcher. An empirical survey was made as a part of the action research; the survey determined user satisfaction in the newly established national digital library. After obtaining the survey results, I suggested that the current way of running the nationwide government-owned digital library should be retained. (C) 2002 Elsevier Science B.V. All rights reserved.

Piezoresistive sensors for force mapping of hip-prostheses

The success of artificial prosthetic replacements depends on the fixation of the artificial prosthetic component after being implanted in the thighbone. The materials for fixation are subject to mechanical stresses, which originate permanent deformations, incipient cracks and even fatigue fractures. This work shows the possibility of monitoring the mechanical stress over time in prosthesis. In this way, highly sensitive silicon thin-film piezoresistive sensors were developed attached to prosthesis and their results compared with commercial strain gauge sensors. Mechanical stress-strain experiments were performed in compressive mode, during 10,000 cycles. Experimental data was acquired at mechanical vibration frequencies of 0.5 Hz, 1 Hz and 5 Hz, and sent to a computer by means of a wireless link. The results show that there is a decrease in sensitivity of the thin-film silicon piezoresistive sensors when they are attached to the prosthesis, but this decrease does not compromise its monitoring performance. The sensitivity, compared to that of commercial strain gauges, is much larger due to their higher gauge factors (-23.5), when compared to the GFs of commercial sensors (2).

Effective swimmer’s action during the grab start technique

The external forces applied in swimming starts have been often studied, but using direct analysis and simple interpretation data processes. This study aimed to develop a tool for vertical and horizontal force assessment based on the swimmers' propulsive and structural forces (passive forces due to dead weight) applied during the block phase. Four methodological pathways were followed: the experimented fall of a rigid body, the swimmers' inertia effect, the development of a mathematical model to describe the outcome of the rigid body fall and its generalization to include the effects of the inertia, and the experimental swimmers' starting protocol analysed with the inclusion of the developed mathematical tool. The first three methodological steps resulted in the description and computation of the passive force components. At the fourth step, six well-trained swimmers performed three 15 m maximal grab start trials and three-dimensional (3D) kinetic data were obtained using a six degrees of freedom force plate. The passive force contribution to the start performance obtained from the model was subtracted from the experimental force due to the swimmers resulting in the swimmers' active forces. As expected, the swimmers' vertical and horizontal active forces accounted for the maximum variability contribution of the experimental forces. It was found that the active force profile for the vertical and horizontal components resembled one another. These findings should be considered in clarifying the active swimmers' force variability and the respective geometrical profile as indicators to redefine steering strategies.

Tribunais nacionais e tutela jurisdicional efetiva: da cooperação à integração judiciária no contencioso da união europeia

Tese de Doutoramento em Ciências Jurídicas (área de especialização em Ciências Jurídicas Públicas).