993 resultados para III-V substrate
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This article is a transcription of an electronic symposium in which active researchers were invited by the Brazilian Society of Neuroscience and Behavior (SBNeC) to discuss the advances of the last decade in the neurobiology of emotion. Four basic questions were debated: 1) What are the most critical issues/questions in the neurobiology of emotion? 2) What do we know for certain about brain processes involved in emotion and what is controversial? 3) What kinds of research are needed to resolve these controversial issues? 4) What is the relationship between learning, memory and emotion? The focus was on the existence of different neural systems for different emotions and the nature of the neural coding for the emotional states. Is emotion the result of the interaction of different brain regions such as the amygdala, the nucleus accumbens, or the periaqueductal gray matter or is it an emergent property of the whole brain neural network? The relationship between unlearned and learned emotions was also discussed. Are the circuits of the former the underpinnings of the latter? It was pointed out that much of what we know about emotions refers to aversively motivated behaviors, like fear and anxiety. Appetitive emotions should attract much interest in the future. The learning and memory relationship with emotions was also discussed in terms of conditioned and unconditioned stimuli, innate and learned fear, contextual cues inducing emotional states, implicit memory and the property of using this term for animal memories. In a general way it could be said that learning modifies the neural circuits through which emotional responses are expressed.
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The opportunistic bacterium Proteus mirabilis secretes a metalloprotease, ZapA, considered to be one of its virulence factors due to its IgA-degrading activity. However, the substrate specificity of this enzyme has not yet been fully characterized. In the present study we used fluorescent peptides derived from bioactive peptides and the oxidized ß-chain of insulin to determine the enzyme specificity. The bradykinin- and dynorphin-derived peptides were cleaved at the single bonds Phe-Ser and Phe-Leu, with catalytic efficiencies of 291 and 13 mM/s, respectively. Besides confirming already published cleavage sites, a novel cleavage site was determined for the ß-chain of insulin (Val-Asn). Both the natural and the recombinant enzyme displayed the same broad specificity, demonstrated by the presence of hydrophobic, hydrophilic, charged and uncharged amino acid residues at the scissile bonds. Native IgA, however, was resistant to hydrolysis by ZapA.
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Clinical stage (CS) is an established indicator of breast cancer outcome. In the present study, a cDNA microarray platform containing 692 genes was used to identify molecular differences between CSII and CSIII disease. Tumor samples were collected from patients with CSII or CSIII breast cancer, and normal breast tissue was collected from women without invasive cancer. Seventy-eight genes were deregulated in CSIII tumors and 22 in CSII tumors when compared to normal tissue, and 20 of them were differentially expressed in both CSII and CSIII tumors. In addition, 58 genes were specifically altered in CSIII and expression of 6 of them was tested by real time RT-PCR in another cohort of patients with CSII or CSIII breast cancer and in women without cancer. Among these genes, MAX, KRT15 and S100A14, but not APOBEC3G or KRT19, were differentially expressed on both CSIII and CSII tumors as compared to normal tissue. Increased HMOX1 levels were detected only in CSIII tumors and may represent a molecular marker of this stage. A clear difference in gene expression pattern occurs at the normal-to-cancer transition; however, most of the differentially expressed genes are deregulated in tumors of both CS (II and III) compared to normal breast tissue.
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Insulin receptor substrate-1 (IRS-1) is the main intracellular substrate for both insulin and insulin-like growth factor I (IGF-I) receptors and is critical for cell mitogenesis. Thyrotropin is able to induce thyroid cell proliferation through the cyclic AMP intracellular cascade; however, the presence of either insulin or IGF-I is required for the mitogenic effect of thyroid-stimulating hormone (TSH) to occur. The aim of the present study was to determine whether thyroid IRS-1 content is modulated by TSH in vivo. Strikingly, hypothyroid goitrous rats, which have chronically high serum TSH levels (control, C = 2.31 ± 0.28; methimazole (MMI) 21d = 51.02 ± 6.02 ng/mL, N = 12 rats), when treated with 0.03% MMI in drinking water for 21 days, showed significantly reduced thyroid IRS-1 mRNA content. Since goiter was already established in these animals by MMI for 21 days, we also evaluated IRS-1 expression during goitrogenesis. Animals treated with MMI for different periods of time showed a progressive increase in thyroid weight (C = 22.18 ± 1.21; MMI 5d = 32.83 ± 1.48; MMI 7d = 31.1 ± 3.25; MMI 10d = 33.8 ± 1.25; MMI 14d = 45.5 ± 2.56; MMI 18d = 53.0 ± 3.01; MMI 21d = 61.9 ± 3.92 mg, N = 9-15 animals per group) and serum TSH levels (C = 1.57 ± 0.2; MMI 5d = 9.95 ± 0.74; MMI 7d = 10.38 ± 0.84; MMI 10d = 17.72 ± 1.47; MMI 14d = 25.65 ± 1.23; MMI 18d = 35.38 ± 3.69; MMI 21d = 31.3 ± 2.7 ng/mL, N = 9-15 animals per group). Thyroid IRS-1 mRNA expression increased progressively during goitrogenesis, being significantly higher by the 14th day of MMI treatment, and then started to decline, reaching the lowest values by the 21st day, when a significant reduction was detected. In the liver of these animals, however, a significant decrease of IRS-1 mRNA was detected after 14 days of MMI treatment, a mechanism probably involved in the insulin resistance that occurs in hypothyroidism. The increase in IRS-1 expression during goitrogenesis may represent an important event associated with the increased rate of cell mitosis promoted by TSH and indicates that insulin and IGF-I are important co-mitogenic factors in vivo, possibly acting through the activation of IRS-1.
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Our aim was to determine if anatomical abnormalities of the upper airway (UA) and facial skeleton of class III severely obese patients are related to the presence and severity of obstructive sleep apnea syndrome (OSAS). Forty-five patients (69% females, mean age 46.5 ± 10.8 years) with a body mass index (BMI) over 40 kg/m² underwent UA and facial skeletal examinations as well as polysomnography. Mean BMI was 49 ± 7 kg/m² and mean neck circumference was 43.4 ± 5.1 cm. Polysomnographic findings showed that 22% had a normal apnea-hypopnea index (AHI) and 78% had an AHI over 5. The presence of OSAS was associated with younger age (P = 0.02), larger neck circumference (P = 0.004), presence of a voluminous lateral wall (P = 0.0002), posteriorized soft palate (P = 0.0053), thick soft palate (P = 0.0014), long uvula (P = 0.04), thick uvula (P = 0.0052), and inferior turbinate hypertrophy (P = 0.04). A larger neck circumference (P = 0.02), presence of a voluminous lateral wall (P = 0.04), posteriorized soft palate (P = 0.03), and thick soft palate (P = 0.04) were all associated with OSAS severity. The prevalence of OSAS in this group was high. A larger neck circumference and soft tissue abnormalities of the UA were markers for both the presence and severity of OSAS. Conversely, no abnormalities in the facial skeleton were associated with OSAS in patients with morbid obesity.
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Cardiac interstitial fibrosis may contribute to ventricular dysfunction and the prognosis of patients with dilated cardiomyopathy. The objective of the present study was to determine if total myocardial collagen content and collagen type III/I (III/I ratio) mRNAs differ in hypertensive, alcoholic, and idiopathic dilated cardiomyopathy subjects. Echocardiography and exercise cardiopulmonary testing were performed in patients with idiopathic (N = 22), hypertensive (N = 12), and alcoholic (N = 11) dilated cardiomyopathy. Morphometric analysis of collagen was performed in fragments obtained by endomyocardial biopsy with picrosirius red staining. The collagen III/I ratio was determined by reverse transcription polymerase chain reaction. Samples of controls (N = 10) were obtained from autopsy. Echocardiographic variables and maximal oxygen uptake were not different among dilated cardiomyopathy groups. Collagen was higher in all dilated cardiomyopathy groups (idiopathic, hypertensive and alcoholic, 7.36 ± 1.09%) versus controls (1.12 ± 0.18%), P < 0.05. Collagen was lower in idiopathic dilated cardiomyopathy (4.97 ± 0.83%) than hypertensive (8.50 ± 1.11%) and alcoholic (10.77 ± 2.09%) samples (P < 0.005 for both). The collagen III/I ratio in all samples from dilated cardiomyopathy patients was higher compared to that in controls (0.29 ± 0.04, P < 0.05) but was the same in the samples from idiopathic (0.77 ± 0.07), hypertensive (0.75 ± 0.07), and alcoholic (0.81 ± 0.16) dilated cardiomyopathy groups. Because of the different physical properties of the types of collagen, the higher III/I ratio may contribute to progressive ventricular dilation and dysfunction in dilated cardiomyopathy patients.
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The manner by which effects of simultaneous mutations combine to change enzymatic activity is not easily predictable because these effects are not always additive in a linear manner. Hence, the characterization of the effects of simultaneous mutations of amino acid residues that bind the substrate can make a significant contribution to the understanding of the substrate specificity of enzymes. In the β-glycosidase from Spodoptera frugiperda (Sfβgly), both residues Q39 and E451 interact with the substrate and this is essential for defining substrate specificity. Double mutants of Sfβgly (A451E39, S451E39 and S451N39) were prepared by site-directed mutagenesis, expressed in bacteria and purified using affinity chromatography. These enzymes were characterized using p-nitrophenyl β-galactoside and p-nitrophenyl β-fucoside as substrates. The k cat/Km ratio for single and double mutants of Sfβgly containing site-directed mutations at positions Q39 and E451 was used to demonstrate that the effect on the free energy of ES‡ (enzyme-transition state complex) of the double mutations (∆∆G‡xy) is not the sum of the effects resulting from the single mutations (∆∆G‡x and ∆∆G‡y). This difference in ∆∆G‡ indicates that the effects of the single mutations partially overlap. Hence, this common effect counts only once in ∆∆G‡xy. Crystallographic data on β-glycosidases reveal the presence of a bidentate hydrogen bond involving residues Q39 and E451 and the same hydroxyl group of the substrate. Therefore, both thermodynamic and crystallographic data suggest that residues Q39 and E451 exert a mutual influence on their respective interactions with the substrate.
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Limitations on tissue proliferation capacity determined by telomerase/apoptosis balance have been implicated in pathogenesis of idiopathic pulmonary fibrosis. In addition, collagen V shows promise as an inductor of apoptosis. We evaluated the quantitative relationship between the telomerase/apoptosis index, collagen V synthesis, and epithelial/fibroblast replication in mice exposed to butylated hydroxytoluene (BHT) at high oxygen concentration. Two groups of mice were analyzed: 20 mice received BHT, and 10 control mice received corn oil. Telomerase expression, apoptosis, collagen I, III, and V fibers, and hydroxyproline were evaluated by immunohistochemistry, in situ detection of apoptosis, electron microscopy, immunofluorescence, and histomorphometry. Electron microscopy confirmed the presence of increased alveolar epithelial cells type 1 (AEC1) in apoptosis. Immunostaining showed increased nuclear expression of telomerase in AEC type 2 (AEC2) between normal and chronic scarring areas of usual interstitial pneumonia (UIP). Control lungs and normal areas from UIP lungs showed weak green birefringence of type I and III collagens in the alveolar wall and type V collagen in the basement membrane of alveolar capillaries. The increase in collagen V was greater than collagens I and III in scarring areas of UIP. A significant direct association was found between collagen V and AEC2 apoptosis. We concluded that telomerase, collagen V fiber density, and apoptosis evaluation in experimental UIP offers the potential to control reepithelization of alveolar septa and fibroblast proliferation. Strategies aimed at preventing high rates of collagen V synthesis, or local responses to high rates of cell apoptosis, may have a significant impact in pulmonary fibrosis.
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Although the metabolism of early bovine embryos has not been fully elucidated, several publications have addressed this important issue to improve culture conditions for cattle reproductive biotechnologies, with the ultimate goal of producing in vitro embryos similar in quality to those developing in vivo. Here, we review general aspects of bovine embryo metabolism in vitro and in vivo, and discuss the use of metabolic analysis of embryos produced in vitro to assess viability and predict a viable pregnancy after transference to the female tract.
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Este trabalho apresenta três aplicações da SFE com diferentes fluídos supercríticos, matrizes e sistemas de extração. Um sistema estático "home made" foi utilizado na pesquisa de fontes alternativas de insumos químicos e energéticos tais como o bagaço de cana-de-açucar e o carvão mineral. Foram usados, respectivamente, o etanol (sem e com catalisador) e o tolueno como fluídos extratores e hidrogênio como gás de pressurização. Na extração dos contaminantes do óleo mineral adsorvidos em bauxita, foi utilizado o dióxido de carbono como fluído extrator em um sistema "home made"/dinâmico. Estudos visando a maximização do rendimento de alguns dos processos também foram realizados, utilizando o planejamento fatorial e a metodologia da superfície de resposta. Os produtos de maior interesse neste trabalho (fração de resinas), obtidos do processo de extração do bagaço de cana-de-açucar e aqueles contaminantes do óleo isolante adsorvidos em bauxita extraídos com fluídos supercríticos foram caracterizados usando cromatografia gasosa de alta resolução com detector de ionização de chama (CGAR - DIC) e cromatografia gasosa de alta resolução com detector seletivo de massas (CGAR - EM) após fracionamento por cromatografia líquida preparativa em 8 frações distintas.
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O ácido fítico, dependendo do valor de pH, apresenta alto potencial quelante, complexando íons metálicos, inibindo, assim, a produção de espécies reativas de oxigênio, responsáveis pela destruição oxidativa em sistemas biológicos. Esse potencial quelante tem fundamentado diversos estudos aplicados à ação antioxidante em produtos alimentícios. O objetivo deste trabalho foi estudar o grau de interação do ácido fítico com os íons metálicos Fe(II) e Fe(III), de importância biológica, em condições próximas às fisiológicas, e a estabilidade destes complexos. Titulações potenciométricas foram conduzidas para determinar as constantes de formação dos complexos ácido fítico-Fe(II) e ácido fítico-Fe(III) em solução aquosa, atmosfera inerte, força iônica 0,100 mol.L-1 de cloreto de potássio e à temperatura de 36 ± 0,1 ºC. Estudos espectroscópicos na região do UV-Vis foram realizados para acompanhar a formação dos complexos em solução. Os complexos ácido fítico-Fe(II) e ácido fítico-Fe(III) foram sintetizados e caracterizados por espectroscopia de absorção na região do infravermelho e por estudos termoanalíticos. Os resultados do conjunto de técnicas utilizadas evidenciaram, tanto em solução como no estado sólido, a presença dos íons metálicos coordenados ao ácido fítico.
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Arkit: 1 arkintunnukseton lehti, A7 B-G8.
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Introdução: A Síndrome Metabólica (SM) tem alta prevalência em hemodiálise (HD) e é fator de risco para doenças cardiovasculares, que são a principal causa de mortalidade na doença renal crônica (DRC). Objetivo: Analisar a frequência do diagnóstico de SM em pacientes em hemodiálise e a diferença na prevalência segundo os critérios do NCEPATP III e do IDF. Métodos: Pacientes de duas clínicas de Fortaleza, com tempo de diálise superior a 3 meses e idade maior ou igual a 18 anos, foram submetidos à medição da circunferência abdominal, pressão arterial (PA), dosagens de glicose, triglicerídeos e HDL-colesterol em jejum. Resultados: Foram incluídos 115 pacientes e a prevalência de SM foi de 41,7% segundo o NCEP-ATP III e de 42,6% segundo o IDF. Entre os 48 pacientes com diagnóstico de SM, de acordo com NCEP-ATP III, 87,5% foram diagnosticados pelo IDF. Entre os 67 pacientes não portadores de SM pelo NCEP-ATP III, 89,5% também não foram diagnosticados pelo IDF. As variáveis da SM segundo o NCEP que tiveram maior prevalência foram o HDL-col alterado em 83,4% dos pacientes e a PA alterada ou uso de anti-hipertensivos em 81,3%. Conclusão: A frequência de SM na população em estudo foi elevada, independentemente do critério utilizado. As variáveis que mais contribuíram para o diagnóstico de SM foram a dislipidemia e a PA. A avaliação rotineira do diagnóstico de SM em HD deve ser implementada, uma vez que pacientes em diálise com SM tem aumento do número de hospitalizações e do risco de eventos cardiovasculares.
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Las semillas de soja muestran una alta sensibilidad a las condiciones climáticas y al manejo durante y después de la cosecha. En el ciclo agrícola 1997/1998 el fenómeno de "El Niño"produjo copiosas lluvias, afectando la calidad de las semillas. La finalidad de este trabajo fue estudiar el comportamiento germinativo diferencial entre semilla de soja cosechada a término y semilla sometida a deterioración a campo (por humedad) y la posible existencia de variabilidad genética, para ese parámetro, en la semilla de soja deteriorada. Se utilizaron veinte variedades pertenecientes al Grupo de Maduración III. De cada variedad se procesaron dos lotes: semilla cosechada a término, bajo condiciones agro climáticas favorables ("buena") y semilla deteriorada por condiciones agro climáticas desfavorables durante el retraso de su cosecha ("mala"). Se realizaron ensayos de germinación, Tetrazolio y conductividad eléctrica para análisis de viabilidad y de vigor y emergencia a campo. En las semillas "buenas"la germinación alcanzó los valores más altos, entre 70% y 80%. Sólo en el 55% de los lotes, el vigor varió entre 32 y 67% y la emergencia a campo entre 31% y 61%. La prueba de vigor por Tetrazolio fue la que mejor evaluó la implantación a campo. Hubo correlación significativa entre todas las pruebas. Los lotes "malos" presentaron germinación muy baja, entre 0 y 27%. No se detectó variabilidad en la respuesta germinativa de las diferentes variedades a condiciones de cosecha desfavorables.