Age polyethism in Plebeia emerina (Friese) (Hymenoptera: Apidae) colonies related to propolis handling

Stingless bees collect plant resins and make it into propolis, although they have a wider range of use for this material than do honey bees (Apis spp.). Plebeia spp. workers employ propolis mixed with wax (cerumen) for constructing and sealing nest structures, while they use viscous (sticky) propolis for defense by applying it onto their enemies. Isolated viscous propolis deposits are permanently maintained at the interior of their colonies, as also seen in other Meliponini species. Newly-emerged Plebeia emerina (Friese) workers were observed stuck to and unable to escape these viscous propolis stores. We examined the division of labor involved in propolis manipulation, by observing marked bees of known age in four colonies of P. emerina from southern Brazil. Activities on brood combs, the nest involucrum and food pots were observed from the first day of life of the marked bees. However, work on viscous propolis deposits did not begin until the 13th day of age and continued until the 56th day (maximum lifespan in our sample). Although worker bees begin to manipulate cerumen early, they seem to be unable to handle viscous propolis till they become older.

Expression of SMAD proteins, TGF-beta/activin signaling mediators, in human thyroid tissues

OBJECTIVE: To investigate the expression of SMAD proteins in human thyroid tissues since the inactivation of TGF-β/activin signaling components is reported in several types of cancer. Phosphorylated SMAD 2 and SMAD3 (pSMAD2/3) associated with the SMAD4 induce the signal transduction generated by TGF-β and activin, while SMAD7 inhibits this intracellular signaling. Although TGF-β and activin exert antiproliferative roles in thyroid follicular cells, thyroid tumors express high levels of these proteins. MATERIALS AND METHODS: The protein expression of SMADs was evaluated in multinodular goiter, follicular adenoma, papillary and follicular carcinomas by immunohistochemistry. RESULTS: The expression of pSMAD2/3, SMAD4 and SMAD7 was observed in both benign and malignant thyroid tumors. Although pSMAD2/3, SMAD4 and SMAD7 exhibited high cytoplasmic staining in carcinomas, the nuclear staining of pSMAD2/3 was not different between benign and malignant lesions. CONCLUSIONS: The finding of SMADs expression in thyroid cells and the presence of pSMAD2/3 and SMAD4 proteins in the nucleus of tumor cells indicates propagation of TGF-β/activin signaling. However, the high expression of the inhibitory SMAD7, mostly in malignant tumors, could contribute to the attenuation of the SMADs antiproliferative signaling in thyroid carcinomas.

Physiological implications of the regulation of vacuolar H+-ATPase by chloride ions

Vacuolar H+-ATPase is a large multi-subunit protein that mediates ATP-driven vectorial H+ transport across the membranes. It is widely distributed and present in virtually all eukaryotic cells in intracellular membranes or in the plasma membrane of specialized cells. In subcellular organelles, ATPase is responsible for the acidification of the vesicular interior, which requires an intraorganellar acidic pH to maintain optimal enzyme activity. Control of vacuolar H+-ATPase depends on the potential difference across the membrane in which the proton ATPase is inserted. Since the transport performed by H+-ATPase is electrogenic, translocation of H+-ions across the membranes by the pump creates a lumen-positive voltage in the absence of a neutralizing current, generating an electrochemical potential gradient that limits the activity of H+-ATPase. In many intracellular organelles and cell plasma membranes, this potential difference established by the ATPase gradient is normally dissipated by a parallel and passive Cl- movement, which provides an electric shunt compensating for the positive charge transferred by the pump. The underlying mechanisms for the differences in the requirement for chloride by different tissues have not yet been adequately identified, and there is still some controversy as to the molecular identity of the associated Cl--conducting proteins. Several candidates have been identified: the ClC family members, which may or may not mediate nCl-/H+ exchange, and the cystic fibrosis transmembrane conductance regulator. In this review, we discuss some tissues where the association between H+-ATPase and chloride channels has been demonstrated and plays a relevant physiologic role.

Hormônio do crescimento e exercício físico: considerações atuais

Embora o hormônio do crescimento (GH) seja um dos hormônios mais estudados, vários de seus aspectos fisiológicos ainda não estão integralmente esclarecidos, incluindo sua relação com o exercício físico. Estudos mais recentes têm aumentado o conhecimento a respeito dos mecanismos de ação do GH, podendo ser divididos em: 1) ações diretas, mediadas pela rede de sinalizações intracelulares, desencadeadas pela ligação do GH ao seu receptor na membrana plasmática; e 2) ações indiretas, mediadas principalmente pela regulação da síntese dos fatores de crescimento semelhantes à insulina (IGF). Tem sido demonstrado que o exercício físico é um potente estimulador da liberação do GH. A magnitude deste aumento sofre influência de diversos fatores, em especial, da intensidade e do volume do exercício, além do estado de treinamento. Atletas, normalmente, apresentam menor liberação de GH induzida pelo exercício que indivíduos sedentários ou pouco treinados. Evidências experimentais demonstram que o GH: 1) favorece a mobilização de ácidos graxos livres do tecido adiposo para geração de energia; 2) aumenta a capacidade de oxidação de gordura e 3) aumenta o gasto energético.

Importância da gordura alimentar na prevenção e no controle de distúrbios metabólicos e da doença cardiovascular

A Organização Mundial da Saúde (OMS) reiterou recentemente que o consumo de dietas inadequadas e a inatividade física estão entre os dez principais fatores de mortalidade. Diversos ensaios aleatorizados demonstram que intervenções alimentares adequadas podem diminuir ou prevenir significativamente o aparecimento de várias doenças crônicas não transmissíveis. Neste contexto, o papel da dieta vem sendo exaustivamente avaliado em estudos clínicos e epidemiológicos. Assim, já foi bem estabelecido na literatura que a quantidade e o tipo de gordura alimentar exercem influência direta sobre fatores de risco cardiovascular, tais como a concentração de lípides e de lipoproteínas plasmáticas, bem como sua associação a processos inflamatórios. Os ácidos graxos participam de complexos sistemas de sinalização intracelular, função que vem sendo bastante explorada. Os ácidos graxos poli-insaturados não somente influenciam a composição das membranas, metabolismo celular e sinais de tradução, mas também modulam a expressão de genes, regulando a atividade e a produção de diversos fatores de transcrição. A proposta deste artigo é rever tópicos relevantes referentes ao metabolismo de lípides e os relacionar a terapias nutricionais que possam contribuir para a prevenção e o tratamento de doenças associadas.

Vitamina D e doenças endocrinometabólicas

Atualmente, a insuficiência/deficiência de vitamina D tem sido considerada um problema de saúde pública no mundo todo, em razão de suas implicações no desenvolvimento de diversas doenças, entre elas, o diabetes melito tipo 2 (DMT2), a obesidade e a hipertensão arterial. A deficiência de vitamina D pode predispor à intolerância à glicose, a alterações na secreção de insulina e, assim, ao desenvolvimento do DMT2. Esse possível mecanismo ocorre em razão da presença do receptor de vitamina D em diversas células e tecidos, incluindo células-β do pâncreas, no adipócito e no tecido muscular. Em indivíduos obesos, as alterações do sistema endócrino da vitamina D, caracterizada por elevados níveis de PTH e da 1,25(OH)2D3 são responsáveis pelo feedback negativo da síntese hepática de 25-OHD3 e também pelo maior influxo de cálcio para o meio intracelular, que pode prejudicar a secreção e a sensibilidade à insulina. Na hipertensão, a vitamina D pode atuar via sistema renina-angiotensina e também na função vascular. Há evidências de que a 1,25(OH)2D3 inibe a expressão da renina e bloqueia a proliferação da célula vascular muscular lisa. Entretanto, estudos prospectivos e de intervenção em humanos que comprovem a efetividade da adequação do status da vitamina D sob o aspecto "prevenção e tratamento de doenças endocrinometabólicas" são ainda escassos. Mais pesquisas são necessárias para se garantir o benefício máximo da vitamina D nessas situações.

A qualidade das refeições de empresas cadastradas no Programa de Alimentação do Trabalhador na cidade de São Paulo

OBJETIVO: Avaliar a qualidade global das refeições oferecidas por Unidades de Alimentação e Nutrição de empresas beneficiárias do Programa de Alimentação do Trabalhador, na cidade de São Paulo. MÉTODOS: Estudo transversal realizado com 72 empresas cadastradas no programa. Foram coletadas informações de três dias consecutivos das refeições oferecidas no almoço, no jantar e na ceia. A qualidade das refeições oferecidas foi avalia pelo Índice de Qualidade da Refeição, e sua análise foi feita de forma estratificada segundo o perfil da empresa obtido pela análise de cluster. RESULTADOS: A média do Índice de Qualidade da Refeição para as grandes refeições foi de 66,25. Foram obtidos dois grupos de empresas na análise de cluster. As empresas do primeiro, composto em sua maioria por empresas do setor de comércio de micro e pequeno porte, cadastradas na modalidade de autogestão e sem supervisão de nutricionista, obtiveram pior qualidade da refeição (Índice=56,23). As empresas do segundo cluster, constituído principalmente por empresas de médio e grande porte do setor industrial, com gestão terceirizada e supervisão de nutricionista, obtiveram pontuação média do Índice de 82,95. CONCLUSÃO: As refeições oferecidas pelas empresas participantes do Programa de Alimentação do Trabalhador não estavam adequadas, segundo o Índice de Qualidade da Refeição. As empresas de menor porte e estrutura tiveram refeições de pior qualidade quando comparadas com as demais, demonstrando que empresas deste perfil são prioritárias para intervenções dentro do Programa de Alimentação do Trabalhador.

O arroz no varejo e os fatores que influenciam o dispêndio das famílias consumidoras

Apesar da idéia consagrada de que arroz é uma commodity e, portanto, pouco passível de diferenciação, há um grande número de produtos, com variação de tipo, classe, padrão, embalagem, marca etc. Observa-se significativa variabilidade nos preços, tanto entre diferentes marcas, fabricantes, lojas, como também para um mesmo produto, em um curto intervalo de tempo. Diante dessas constatações, questiona-se qual o efeito da estratégia de compra de arroz por parte dos consumidores sobre seus dispêndios. Este trabalho utiliza modelos matemáticos para simular o processo de decisão de compra dos consumidores com diferentes perfis de preferência, diante dos produtos nas gôndolas dos supermercados em uma cidade no estado do Rio Grande do Sul e outra em São Paulo.

Exercise x BCAA supplementation in young trained rats: what are their effects on body growth?

The purpose of this study was to evaluate whether Branched-chain amino acids (BCAAs) supplementation had any beneficial effects on growth and metabolic parameters of young rats submitted to chronic aerobic exercise. Thirty-two young rats (age: 21-d) were randomly assigned to four experimental groups (n = 8): Supplemented Trained (Sup/Ex), Control Trained (Ctrl/Ex), Supplemented Sedentary (Sup/Sed) and Control Sedentary (Ctrl/Sed). The trained groups underwent a five-week swimming protocol and received supplemented (45 mg BCAA/body weight/day) or control ration. Trained animals presented a lower body length and a higher cartilage weight, regardless of supplementation. Physical activity was responsible for a substantial reduction in proteoglycan synthesis in cartilage tissue, and BCAA supplementation was able to attenuate this reduction and also to improve glycogen stores in the liver, although no major differences were found in body growth associated to this supplementation.

Escalas concorrentes para a mensuração da qualidade percebida: uma comparação entre a SERVQUAL e a RSQ

There is no doubt about the importance of service quality as a factor of businesses' success, but to measure this quality has proved to be a challenge when one considers different environmental contexts. Given this, the main goal of this paper was to test two measurement scales of perceived set-vice quality. The comparison between Service Quality scale (Servqual) and Retail Set-vice Quality (RSQ) was conducted by means of a survey with 351 participants, clients of a home center stores chain located in the city of Sao Paulo. The data were analyzed using both exploratory and confirmatory factor analysis. As a result, both scales demonstrated acceptable levels of reliability and validity However; the RSQ demonstrated a better performance in the nomological test since it was able to explain 43% of the loyalty towards the retailer; while the Servqual scale explained only 11%.

Plasmodium vivax: Induction of CD4(+)CD25(+)FoxP3(+) Regulatory T Cells during Infection Are Directly Associated with Level of Circulating Parasites

Circulation CD4(+)CD25(+)FoxP3(+) regulatory T cells (Tregs) have been associated with the delicate balancing between control of overwhelming acute malaria infection and prevention of immune pathology due to disproportionate inflammatory responses to erythrocytic stage of the parasite. While the role of Tregs has been well-documented in murine models and P. falciparum infection, the phenotype and function of Tregs in P. vivax infection is still poorly characterized. In the current study, we demonstrated that patients with acute P. vivax infection presented a significant augmentation of circulating Tregs producing anti-inflammatory (IL-10 and TGF-beta) as well as pro-inflammatory (IFN-gamma, IL-17) cytokines, which was further positively correlated with parasite burden. Surface expression of GITR molecule and intracellular expression of CTLA-4 were significantly upregulated in Tregs from infected donors, presenting also a positive association between either absolute numbers of CD4(+)CD25(+)FoxP3(+)GITR(+) or CD4(+)CD25(+)FoxP3(+)CTLA-4(+) and parasite load. Finally, we demonstrate a suppressive effect of Treg cells in specific T cell proliferative responses of P. vivax infected subjects after antigen stimulation with Pv-AMA-1. Our findings indicate that malaria vivax infection lead to an increased number of activated Treg cells that are highly associated with parasite load, which probably exert an important contribution to the modulation of immune responses during P. vivax infection.

ACE as a Mechanosensor to Shear Stress Influences the Control of Its Own Regulation via Phosphorylation of Cytoplasmic Ser(1270)

Objectives: We tested whether angiotensin converting enzyme (ACE) and phosphorylation of Ser(1270) are involved in shear-stress (SS)-induced downregulation of the enzyme. Methods and Results: Western blotting analysis showed that SS (18 h, 15 dyn/cm(2)) decreases ACE expression and phosphorylation as well as p-JNK inhibition in human primary endothelial cells (EC). CHO cells expressing wild-type ACE (wt-ACE) also displayed SS-induced decrease in ACE and p-JNK. Moreover, SS decreased ACE promoter activity in wt-ACE, but had no effect in wild type CHO or CHO expressing ACE without either the extra-or the intracellular domains, and decreased less in CHO expressing a mutated ACE at Ser(1270) compared to wt-ACE (13 vs. 40%, respectively). The JNK inhibitor (SP600125, 18 h), in absence of SS, also decreased ACE promoter activity in wt-ACE. Finally, SS-induced inhibition of ACE expression and phosphorylation in EC was counteracted by simultaneous exposure to an ACE inhibitor. Conclusions: ACE displays a key role on its own downregulation in response to SS. This response requires both the extra- and the intracellular domains and ACE Ser(1270), consistent with the idea that the extracellular domain behaves as a mechanosensor while the cytoplasmic domain elicits the downstream intracellular signaling by phosphorylation on Ser(1270).

The Ultrastructural Study of Tumorigenic Cells Using Nanobiomarkers

Despite recent advances, patients with malignant brain tumors still have a poor prognosis. Glioblastoma (WHO grade 4 astrocytoma), the most malignant brain tumor, represents 50% of all astrocytomas, with a median survival rate of <1 year. It is, therefore, extremely important to search for new diagnostic and therapeutic approaches for patients with glioblastoma. This study describes the application of superparamagnetic nano-particles of iron oxide, as well as monoclonal antibodies, of immunophenotypic significance, conjoined to quantum dots for the ultrastructural assessment of glioblastoma cells. For this proposal, an immunophenotypic study by flow cytometry was carried out, followed by transmission electron microscopy analysis. The process of tumor cell labeling using nanoparticles can successfully contribute to the identification of tumorigenic cells and consequently for better understanding of glioblastoma genesis and recurrence. In addition, this method may help further studies in tumor imaging, diagnosis, and prognostic markers detection.

Increased myoepithelial cells of bronchial submucosal glands in fatal asthma

Background: Fatal asthma is characterised by enlargement of bronchial mucous glands and tenacious plugs of mucus in the airway lumen. Myoepithelial cells, located within the mucous glands, contain contractile proteins which provide structural support to mucous cells and actively facilitate glandular secretion. Objectives: To determine if myoepithelial cells are increased in the bronchial submucosal glands of patients with fatal asthma. Methods: Autopsied lungs from 12 patients with fatal asthma (FA), 12 patients with asthma dying of non-respiratory causes (NFA) and 12 non-asthma control cases (NAC) were obtained through the Prairie Provinces Asthma Study. Transverse sections of segmental bronchi from three lobes were stained for mucus and smooth muscle actin and the area fractions of mucous plugs, mucous glands and myoepithelial cells determined by point counting. The fine structure of the myoepithelial cells was examined by electron microscopy. Results: FA was characterised by significant increases in mucous gland (p = 0.003), mucous plug (p = 0.004) and myoepithelial cell areas (p = 0.017) compared with NAC. When the ratio of myoepithelial cell area to total gland area was examined, there was a disproportionate and significant increase in FA compared with NAC (p = 0.014). Electron microscopy of FA cases revealed hypertrophy of the myoepithelial cells with increased intracellular myofilaments. The NFA group showed changes in these features that were intermediate between the FA and NAC groups but the differences were not significant. Conclusions: Bronchial mucous glands and mucous gland myoepithelial cell smooth muscle actin are increased in fatal asthma and may contribute to asphyxia due to mucous plugging.

IL-17 Produced during Trypanosoma cruzi Infection Plays a Central Role in Regulating Parasite-Induced Myocarditis

Background: Chagas disease is a neglected disease caused by the intracellular parasite Trypanosoma cruzi. Around 30% of the infected patients develop chronic cardiomyopathy or megasyndromes, which are high-cost morbid conditions. Immune response against myocardial self-antigens and exacerbated Th1 cytokine production has been associated with the pathogenesis of the disease. As IL-17 is involved in the pathogenesis of several autoimmune, inflammatory and infectious diseases, we investigated its role during the infection with T. cruzi. Methodology/Principal Findings: First, we detected significant amounts of CD4, CD8 and NK cells producing IL-17 after incubating live parasites with spleen cells from normal BALB/c mice. IL-17 is also produced in vivo by CD4(+), CD8(+) and NK cells from BALB/c mice on the early acute phase of infection. Treatment of infected mice with anti-mouse IL-17 mAb resulted in increased myocarditis, premature mortality, and decreased parasite load in the heart. IL-17 neutralization resulted in increased production of IL-12, IFN-gamma and TNF-alpha and enhanced specific type 1 chemokine and chemokine receptors expression. Moreover, the results showed that IL-17 regulates T-bet, ROR gamma t and STAT-3 expression in the heart, showing that IL-17 controls the differentiation of Th1 cells in infected mice. Conclusion/Significance: These results show that IL-17 controls the resistance to T. cruzi infection in mice regulating the Th1 cells differentiation, cytokine and chemokine production and control parasite-induced myocarditis, regulating the influx of inflammatory cells to the heart tissue. Correlations between the levels of IL-17, the extent of myocardial destruction, and the evolution of cardiac disease could identify a clinical marker of disease progression and may help in the design of alternative therapies for the control of chronic morbidity of chagasic patients.