Efects of plasma corticosteroid concentration on the osmotic threshold for vasopressin releasing in Chagas' disease

The osmotic threshold for vasopressin release was studied in normal patients (n = 7) and in patients with the chronic form of Chagas'disease (n = 11). Positive correlation between osmotic threshold and plasma cortisol concentration was obtained for the Controls (y1 = 273,30 + 0,75x i; r = 0,78;P < 0,05), suggesting a modulating effect of cortisol on vasopressin release. The lack of correlation between the two parameters for the chronic chagasic patients was interpreted, on the basis of the general denervation associated with Chagas ' disease, to be the result of neuronal destruction in hypothalamic and/or extrahypothalamic centers related to the secretory control of vasopressin.

Atividade colinesterásica no plasma e em eritrócitos de pacientes com as formas cardíaca e indeterminada da doença de Chagas

A atividade colinesterásica foi determinada no plasma e em eritrócitos de 10 indivíduos normais e em 26 pacientes chagásicos crônicos, sendo 6 com insuficiência cardíaca congestiva compensada, 10 com cardiopatia sem insuficiência cardíaca congestiva e 10 com a forma indeterminada. Os valores enzimáticos encontrados foram (média ±sd): 2196 ± 442 UI/L no plasma e 19,4 ± 3,3 Ul/g Hb em eritrócitos do grupo controla; 2291 ± 317 UI/L no plasma e 19,2 ±3,7 Ul/g Hb em eritrócitos dos chagásicos com insuficiência cardíaca congestiva compensada; 2445 ± 357 UI/L no plasma e 18,3 + 3,0 Ul/g Hb em eritrócitos dos cardiopatas chagásicos sem insuficiência cardíaca congestiva; 2006 ± 327 UI/L no plasma e 17,8 ± 3,1 Ul/g Hb em eritrócitos de chagásicos com a forma indeterminada. Nossos dados mostram que o comprometimento neuronal que ocorre nos cardiopatas chagásicos crônicos não é suficiente para levar a alterações significativas (p > 0,05) das atividades colinesterásicas no plasma e em eritrócitos.

Cortisol e testosterona no plasma da grávida e no líquido amniótico: variação com o relaxamento e correlação com o rácio digital 2D:4D no recém-nascido

RESUMO: Conclusão - Este estudo sugere que mulheres grávidas beneficiam da prática rotineira de 30 min de relaxamento perante a eminência de um acontecimento indutor de stress. O benefício será tanto psicológico como fisiológico e será mais marcado de manhã do que de tarde. As mulheres com maior tendência ansiosa, tipicamente as mais jovens e com menos idade gestacional, serão as que mais beneficiam. Entre os tipos de intervenção experimentados, todos eles não dispendiosos, a audição de música foi globalmente o mais eficaz para o propósito pretendido. A variação do cortisol e a variação da testosterona estão altamente correlacionadas, e este efeito poderá ser explorado em futuras intervenções relaxantes. Programas curtos de relaxamento poderão conduzir a benefícios para o bem-estar psicológico e para a saúde da grávida, com benefícios adicionais no desfecho da gravidez. O rácio digital 2D:4D do recém-nascido apresenta características sexualmente dimórficas, sendo mais baixo em rapazes que em raparigas, confirmando a influência dos androgénios pré-natais, mas há grande sobreposição entre os sexos pelo que, isoladamente, não pode ser utilizado como marcador de risco. No entanto, se associado a outros marcadores biológicos, como o peso ao nascer e a circunferência cerebral, entre outros, poderá ser um parâmetro a valorizar desde cedo, possivelmente no acompanhamento pediátrico. Nas raparigas, o RD da mãe e a testosterona no LA explicam uma proporção significativa do seu 2D:4D. Em ambos os sexos, o rácio 2D:4D aumenta após o nascimento e o dimorfismo sexual observado com base em amostras de crianças com mais de dois anos de idade, é afectado pela testosterona pós-natal, especialmente no que se refere à mão direita.----------ABSTRACT: Conclusions - This study suggests that pregnant women would benefit from the routine practice of 30min relaxation when at the imminence of a stressful event. The benefit would be both psychological and physiological and would be more pronounced in the morning than in the afternoon. Women tending to be more anxious, typically younger and at a lower gestational age, are the ones that benefit the most. Among the interventions investigated, all being non-expensive and easy to implement, listening to relaxing music was globally the most efficient for the benefit intended. The variation of cortisol and the variation of testosterone are significantly correlated, an association that might be used in future relaxation interventions. It is feasible to conceive short relaxation programs aimed at benefiting psychological well-being and health in pregnancy, with additional benefits for pregnancy outcome. The digital ratio 2D:4D is sexually dimorphic, being lower in males than in females, confirming the influence of pre-natal androgens. There is however large overlap between sexes, rendering the 2D:4D a risk marker not to be used in isolation but rather in association with other markers, like for instance the weight at birth and the head circumference, wherein it may be a relevant parameter for pediatric follow-up. In newborn females, a significant amount of variability in 2D:4D is accounted for by their mother’s digital ratio and AF testosterone. In both sexes, the 2D:4D ratio increases following birth and sexual dimorphism,as assessed from samples of subjects with more than 2 years of age, is affected by post-natal testosterone, especially in what concerns the right hand.

Longitudinal comparison between plasma and seminal HIV-1 viral loads during antiretroviral treatment

This study was designed to investigate the impact of anti-retroviral therapy on both plasma and seminal HIV-1 viral loads and the correlation between viral loads in these compartments after treatment. Viral load, CD4+ and CD8+ T-cell counts were evaluated in paired plasma and semen samples from 36 antiretroviral therapy-naïve patients at baseline and on days 45, 90, and 180 of treatment. Slopes for blood and seminal viral loads in all treated patients were similar (p = 0.21). Median HIV-1 RNA titers in plasma and semen at baseline were 4.95 log10 and 4.48 log10 copies/ml, respectively. After 180 days of therapy, the median viral load declined to 3.15 log10 copies/ml (plasma) and 3.2 log10 copies/ml (semen). At this timepoint 22 patients presented HIV-1 viral load below 400 copies/ml in either plasma or semen, but only 9 had viral loads below 400 copies/ml in both compartments.

Alterações nos níveis de colesterol, triglicerídeo e fosfolipídeo total em plasma de Callithrix jacchus (sagüi) reinfectado por Schistosoma mansoni

Pouco se conhece a cerca de alterações nos lipídeos plasmáticos devido à reinfecção por Schistosoma mansoni. Neste trabalho, foram avaliadas alterações nos lipídeos plasmáticos decorrentes de uma reinfecção por Schistosoma mansoni no primata não humano Callithrix jacchus (sagüi). Amostras de sangue dos animais, antes e após serem infectados e reinfectados, foram coletadas por punção venosa, anticoaguladas com EDTA (1mg/mL) e centrifugadas a 2.500xg para obtenção do plasma. Os níveis plasmáticos de colesterol total, colesterol éster, fosfolipídeo total e triglicerídeo foram determinados por métodos espectrofotométricos. Os resultados mostraram haver redução significativa nas concentrações de colesterol total, colesterol esterificado, triglicerídeo e fosfolipídeo total em plasma de animais reinfectados por Schistosoma mansoni, em comparação com os mesmos animais antes da infecção e após uma infecção. Este estudo mostra que uma segunda infecção por Schistosoma mansoni causa alterações lipídicas plasmáticas significativamente mais acentuadas que as decorrentes de uma única infecção.

Characterization of mannose-binding lectin plasma levels and genetic polymorphisms in HIV-1-infected individuals

INTRODUCTION: The present study investigated the association between mannose-binding lectin (MBL) gene polymorphism and serum levels with infection by HIV-1. METHODS: Blood samples (5mL) were collected from 97 HIV-1-infected individuals resident in Belém, State of Pará, Brazil, who attended the Special Outpatient Unit for Infections and Parasitic Diseases (URE-DIPE). CD4+ T-lymphocyte count and plasma viral load were quantified. A 349bp fragment of exon 1 of the MBL was amplified via PCR, using genomic DNA extracted from controls and HIV-1-infected individuals, following established protocols. MBL plasma levels of the patients were quantified using an enzyme immunoassay kit. RESULTS: Two alleles were observed: MBL*O, with a frequency of 26.3% in HIV-1-infected individuals; and the wild allele MBL*A (73.7%). Similar frequencies were observed in the control group (p > 0.05). Genotype frequencies were distributed according to the Hardy-Weinberg equilibrium in both groups. Mean MBL plasma levels varied by genotype, with statistically significant differences between the AA and AO (p < 0.0001), and AA and OO (p < 0.001) genotypes, but not AO and OO (p = 0.17). Additionally, CD4+ T-lymphocytes and plasma viral load levels did not differ significantly by genotype (p > 0.05). CONCLUSIONS: The results of this study do not support the hypothesis that MBL gene polymorphism or low plasma MBL concentrations might have a direct influence on HIV-1 infection, although a broader study involving a large number of patients is needed.

Desenvolvimento de novas ferramentas analíticas para a monitorização da actividade da Paraoxonase 1 em amostras de plasma humano

Segundo a Organização Mundial da Saúde (OMS), as doenças cardiovasculares (DCV) são a principal causa de morte nos países desenvolvidos. Há uma necessidade urgente de métodos eficazes para a detecção precoce de doenças cardiovasculares, devido à falta de factores de risco convencionais. Os níveis elevados de homocisteína (Hcy) no sangue, homocisteinemia, são um factor de risco independente bem estabelecido para DCV. De acordo com alguns autores, a conversão metabólica de Hcy no metabolito tóxico Hcy-Tl e subsequente N-homocisteinilação de proteínas induz a agregação e a formação de amiloide, contribuindo assim para a alterações próaterogénicas no sistema cardiovascular. A enzima associada à lipoproteína de alta densidade (HDL), paraoxonase 1 (PON1), é capaz de hidrolisar o metabolito tóxico Hcy-Tl de volta a Hcy no soro humano, como observado em estudos recentes que indicam o papel de patogénese em DCV da hPON1. As paraoxonases de soro (PON1, PON2 e PON3) são hidrolases dependentes de cálcio, que pertencem a uma família de enzimas que exibem propriedades antioxidantes e anti-inflamatórias. Foram identificadas três actividades catalíticas principais para PON1: (i) actividade paraoxonase, que corresponde à conversão hidrolítica de paraoxon em p-nitrofenol e a dietil fosfato, (ii) a actividade arilesterase que promove a hidrólise de ésteres aromáticos, e a (iii) actividade de lactonase, que catalisa a hidrólise de Hcy a Hcy-Tl, sendo considerada a actividade principal da PON1. Vários estudos têm relacionado estas actividades enzimáticas a diversas patologias, o que sugere a sua potencial utilidade no diagnóstico clínico. Neste trabalho pretende-se desenvolver um novo método electroquímico para a detecção fácil do substrato e produto resultantes da hidrólise enzimática de paraoxon pela hPON1. Utilizando uma célula electroquímica constituída por um eléctrodo de referência Ag /AgCl., um contra-eléctrodo de Pt e um electrodo de trabalho de carbono vítreo, o paraoxon e p-nitrofenol foram detectados simultaneamente por voltametria de onda quadrada, numa janela de potencial de [-0,3;-1,2] V. Os resultados dos ensaios com a enzima testada a pH 7,6 e 37°C, na presença de paraoxon e utilizando plasma humano como uma fonte de PON1 serão discutidos. Usando a mesma composição de célula electroquímica, Hcy e Hcy-Tl foram estudados utilizando diferentes interfaces e tipos de tratamento para testar a melhor maneira possível de detecção das duas espécies na mesma experiência electroquímica.

Relationship between plasma creatinine concentration and glomerular filtration in preterm newborn infants

Fluid management and dosage regimens of drugs in preterm infants should be based on the glomerular filtration rate. The current methods to determine glomerular flitration rate are invasive, time-consuming, and expensive. In contrast, creatinine clearance can be easy obtained and quickly determined. The purpose of this study was to compare plasma creatinine on the third and seventh day of life in preterm newborn infants, to evaluate the influence of maternal creatinine, and to demonstrate creatinine clearance can be used as a reliable indicator of glomerular filtration rate. We developed a prospective study (1994) including 40 preterm newborns (gestational age < 37 weeks), average = 34 weeks; birth weight (average) = 1840 g, in the first week of life. Inclusion criteria consisted of: absence of renal and urinary tract anomalies; O2 saturation 3 92%; adequate urine output (>1ml/kg/hr); normal blood pressure; absence of infections and no sympathomimetic amines in use. A blood sample was collected to determine plasma creatinine (enzymatic method) on the third and seventh day of life and creatinine clearance (CrCl) was obtained using the following equation: , k = 0.33 in preterm infant All plasma creatinine determinations showed normal values [third day: 0.78 mg/dl ± 0.24 (mean ± SD)and seventh day: 0.67 mg/dl ± 0.31 - (p>0.05)]. Also all creatinine clearance at third and seventh day of life were normal [third day: 19.5 ml/min ± 5.2 (mean ± SD) and seventh day: 23.8 ml/min ± 7.3 - (p>0,05)]. All preterm infants developed adequate renal function for their respective gestational age. In summary, our results indicate that, for clinical practice, the creatinine clearance, using newborn length, can be used to estimate glomerular filtration rate in preterm newborn infants.

Plasma nitriding of AA2011 alloy and surface characterization by NDT techniques

Al-Cu alloys are widely used in the aerospace and automotive industries due to their high specific strength in some tempered conditions. However, due to poor corrosion and wear resistance, they are often anodized and/or painted. Plasma nitriding has been proposed as an alternative, though the developments in this technique are still in a recent stage for Al alloys. Electrical characterization techniques are well implemented NDTs in the industry because of good accuracy associated with lower cost, compared to other methods. Some, like eddy currents and 4-point probe techniques, are often used in coating inspection. The objective of this study was to perform Al nitriding at low temperatures to minimize the tempering initial condition damage and to assess the feasibility of eddy currents technique as a method for evaluating surface properties. The work developed can be divided in two stages. The first one was the process tuning, done at the Shibaura Institute of Technology, in Tokyo; and the second was the electrical characterization done in Faculdade de Ciências e Tecnologia, UNL. Low temperature nitriding of AA2011 alloy specimens was successfully achieved. Electrical conductivity results show that lift-off measurements by eddy currents testing can be related to surface properties.

Nonsolvent induced phase separation preparation of poly(vinylidene fluoride-co-chlorotrifluoroethylene) membranes with tailored morphology, piezoelectric phase content and mechanical properties

Poly(vinylidene fluoride-co-chlorotrifluoroethylene) – P(VDF-CTFE) membranes are increasingly interesting for a wide range of applications, including battery separators, filtration membranes and biomedical applications. This work reports on the morphology, hydrophobicity, thermal and mechanical properties variation of P(VDF-CTFE) membranes processed by nonsolvent induced phase separation technique (NIPS) as a function of the main processing parameters. All membranes show a porous structure composed of large spherulites, (interconnected) micropores and/or microvoids depending on the processing conditions used that in turn affect their hydrophobicity and mechanical properties. The degree of crystallinity of the membranes remains approximately constant with a value of about 15 %, except for the membranes immediately immersed in ethanol, which is of about 23 %. In turn, the crystalline phases present in the copolymer is mainly affected by the temperature and nonsolvent characteristics of the coagulation bath, the β-phase content ranging from 33 to 100 %, depending on those processing parameters. It was show that the temperature of water-based coagulation bath plays an important role in order to produce structurally uniform and homogeneous porous membranes, which is particularly important from the point of view of technological applications.

High performance electromechanical actuators based on ionic liquid/poly(vinylidene fluoride)

Due to the increasing need of low voltage actuators, independent from electrochemical processes, electroactive actuators based on poly(vinylidene fluoride) composites with 10, 25 and 40 % of 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [C2mim] [NTf2], ionic liquid are prepared by solvent casting and melting. We show that the charge structure of [C2mim] [NTf2] induces the complete piezoelectric -phase crystallization of the PVDF within the composite and decreases its crystallinity fraction significantly. [C2mim] [NTf2] also works as a plasticizer of PVDF, reducing the elastic modulus down to 12 % of the initial value. Moreover, the composites show significant displacement and bending under applied voltages of 2, 5 and 10 Vpp. The displacement and bending of the composite membranes are also evaluated as a function of [C2mim] [NTf2] content and sample thickness. Increasing amounts of ionic liquid result in larger deformations independently of the applied voltage.

Gd2O3: Eu Nanoparticle-Based Poly(vinylidene fluoride) Composites for Indirect X-ray Detection

Polymer based scintillator composites have been fabricated by combining poly(vinylidene fluoride) (PVDF) and Gd2O3:Eu nanoparticles (50nm). PVDF has been used since it is a flexible and stable binder matrix and highly resistance to thermal and light deterioration. Gd2O3:Eu has been selected as scintillator material due to its wide band gap, high density and suitable visible light yield. The structural, mechanical, thermal and electrical characteristics of the composites were studied as a function of filler content, together with their performance as scintillator material. The introduction of Gd2O3:Eu nanoparticles into the PVDF matrix does not influence the morphology of the polymer or the degree of crystallinity. On the other hand, an increase of the Young´s modulus with respect to PVDF matrix is observed for filler contents of 0.1-0.75 wt.%. The introduction of Gd2O3:Eu into the PVDF matrix increases dielectric constant and DC electrical conductivity as well as the visible light yield in the nanocomposite, being this increase dependent upon Gd2O3:Eu content and X-ray input power. In this way, Gd2O3:Eu/PVDF composites shows suitable characteristics to be used as X-ray radiation transducers, in particular for large area applications.

Poly(vinylidene fluoride-co-chlorotrifluoroethylene) (PVDF-CTFE) lithium-ion battery separator membranes prepared by phase inversion

Separator membranes based on poly(vinylidene fluoride-co-chlorotrifluoroethylene) (PVDF-CTFE) were prepared by solvent casting technique based on its phase diagram in N,Ndimethylformamide (DMF) solvent. The microstructure of the PVDF-CTFE separator membranes depends on the initial position (temperature and concentration) of the solution in the phase diagram of the PVDF-CTFE/DMF system. A porous microstructure is achieved for PVDF-CTFE membranes with solvent evaporation temperature up to 50 ºC for a polymer/solvent relative concentration of 20 wt%. The ionic conductivity of the separator depends on the degree of porosity and electrolyte uptake, the highest room temperature value being 1.5 mS.cm-1 for the sample with 20 wt% of polymer concentration and solvent evaporation temperature at 25 ºC saturated with 1 mol L-1 lithium bis (trifluoromethanesulfonyl) imide (LiTFSI) in propylene carbonate (PC). This PVDF-CTFE separator membrane in Li/C-LiFePO4 half-cell shows good cyclability and rate capability, showing a discharge value after 50 cycles of 92 mAh.g-1 at 2 C, which is still 55% of the theoretical value. PVDF-CTFE separators are thus excellent candidates for high-power and safety lithium-ion batteries applications.

Ag-TiNx electrodes deposited on piezoelectric poly(vinylidene fluoride) for biomedical sensor applications

Electroactive polymers are one of the most interesting class of polymers used as smart materials in various applications, such as the development of sensors and actuators for biomedical applications in areas such as smart prosthesis, implantable biosensors and biomechanical signal monitoring, among others. For acquiring or applying the electrical signal from/to the piezoelectric material, suitable electrodes can be produced from Ti based coatings with tailored multifunctional properties, conductivity and antibacterial characteristics, through Ag inclusions. This work reports on Ag-TiNx electrodes, deposited by d. c. and pulsed magnetron sputtering at room temperature on poly(vinylidene fluoride), PVDF, the all-round best piezoelectric polymer.. Composition of the electrodes was assessed by microanalysis X-ray system (EDS - energy dispersive spectrometer). The XRD results revealed that the deposition conditions preserve the polymer structure and suggested the presence of crystalline fcc-TiN phase and fcc-Ag phase in samples with N2 flow above 3 sccm. According to the results obtained from SEM analysis, the coatings are homogeneous and Ag clusters were found for samples with nitrogen flow above 3 sccm. With increasing nitrogen flow, the sheet resistivity tend to be lower than the samples without nitrogen, leading also to a decrease of the piezoelectric response. It is concluded that the deposition conditions do significantly affect the piezoelectric polymer, which maintain its characteristics for sensor/actuator applications.

Dielectric relaxation and ferromagnetic resonance in magnetoelectric (Polyvinylidene-fluoride)/ferrite composites

In this work the dielectric properties and ferromagnetic resonance of Polyvinylidene- uoride embedded with 10 wt. % of NiFe2O4 or Ni0.5Zn0.5Fe2O4 nanoparticles are presented. The mechanisms of the dielectric relaxation in these two composites do not differ from each other. For more precise characterization of the dielectric relaxation, a two dimensional distribution of relaxation times was calculated from the temperature dependencies of the complex dielectric permittivity. The results obtained from the 2D distribution and the mean relaxation time are found to be consistent. The dynamics of the dielectric permittivity is described by the Arrhenius law. The energy and attempt time of the dielectric relaxators lie in a narrow energy and time region thus proving that the single type chains of polymer are responsible for a dispersion. The magnetic properties of the composites were investigated using the fer- romagnetic resonance. A single resonance line was observed for both samples. From the temperature dependence (100 K - 310 K) of the resonance eld and linewidth, the origin of the observed line was attributed to the NiFe2O4 and Ni0.5Zn0.5Fe2O4 superparamagnetic nanoparticles. By measuring lms at dif- ferent orientations with respect to the external magnetic eld, the angular dependence of the resonance was observed, indicating the magnetic dipolar in-plane interactions.