A buck-boost converter with extended duty-cycle range in the buck voltage region for renewable energy sources

Buck-boost DC-DC converters are useful as DC grid interfaces for renewable energy resources. In the classical buck-boost converter, output voltages smaller than the input voltage (the buck region) are observed for duty cycles between 0 and 0.5. Several recent buck-boost converters have been designed to present higher voltage gains. Nevertheless, those topologies show a reduced duty-cycle range, leading to output voltages in the buck region, and thus require the use of very low duty cycles to achieve the lower range of buck output voltages. In this work, we propose a new buck-boost DC-DC converter that privileges the buck region through the extension of the duty-cycle range, enabling buck operation. In fact, the converter proposed here allows output voltages below the input voltage even with duty cycles higher than 0.6. We present the analysis, design, and testing of the extended buck-boost DC-DC converter. Several tests were conducted to illustrate the characteristics of the extended buck-boost DC-DC converter. Test results were obtained using both simulation software and a laboratory prototype.info:eu-repo/semantics/publishedVersio

The obestatin receptor (GPR39) is expressed in human adipose tissue and is down-regulated in obesity-associated type 2 diabetes mellitus

The G protein-coupled receptor 39 (GPR39) has recently been identified as the receptor for obestatin, a peptidic hormone involved in energy homeostasis. However, the expression levels of this receptor in human adipose tissue in obesity and obesity-associated type 2 diabetes mellitus (T2DM) remain unknown. Therefore, we evaluated the actual presence of GPR39 mRNA in human adipose tissue and whether GPR39 expression levels are altered in obesity and obesity-associated T2DM. DESIGN: Omental adipose tissue biopsies obtained from 15 women were used in the study. Patients were classified as lean (body mass index 20.8 +/- 1.0 kg/m(2)), obese normoglycaemic (body mass index 48.4 +/- 2.1 kg/m(2)) and obese T2DM patients (body mass index 52.6 +/- 4.9 kg/m(2)). Anthropometric measurements and biochemical profiles were assessed for each subject. Real-time RT-PCR analyses were performed to quantify transcript levels of GPR39 and adiponectin. RESULTS: Obese T2DM patients exhibited significantly lower GPR39 expression levels compared to lean (P = 0.016) and obese normoglycaemic subjects (P = 0.008), while no differences between lean and obese normoglycaemic patients were observed. The mRNA expression levels of GPR39 were negatively correlated to fasting glucose concentrations (r = -0.581, P = 0.023), while exhibiting a positive correlation to adiponectin mRNA expression levels (r = 0.674, P = 0.006). CONCLUSION: GPR39 is expressed in human adipose tissue. The reduced expression levels of GPR39 in omental adipose tissue observed in obese patients with T2DM suggest an involvement of obestatin signalling in glucose homeostasis and T2DM development

Expression of caveolin-1 in human adipose tissue is upregulated in obesity and obesity-associated type 2 diabetes mellitus and related to inflammation

Caveolin-1 (CAV-1) plays important roles in many aspects of cellular biology, including vesicular transport, cholesterol homeostasis and signal transduction. The aim of the present study was to explore gene expression levels of CAV-1 in human adipose tissue in obesity and obesity-associated type 2 diabetes mellitus (T2DM) and to analyse its potential implication in the inflammatory state associated with obesity. DESIGN AND METHODS: Visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) obtained from 15 females were used in the study. Patients were classified as lean (BMI 20.8 +/- 1.0 kg/m(2)) or obese (BMI 50.5 +/- 2.6 kg/m(2)). The obese group was further subclassified as normoglycaemic (NG) or patients with T2DM. Anthropometric measurements as well as circulating metabolites, hormones and adipokines were determined. Real-time polymerase chain reaction (PCR) analyses were performed to quantify transcript levels of CAV-1 and monocyte chemoattractant protein (MCP-1). RESULTS: The presence of CAV-1 protein was detected in VAT and SAT by immunohistochemistry. Both obese NG and with T2DM patients exhibited significantly higher CAV-1 expression levels in VAT and SAT compared with lean subjects (P < 0.05). No differences between obese NG and T2DM patients were observed in VAT. However, obese T2DM patients were found to have higher CAV-1 expression levels in SAT (P < 0.05) compared with obese NG patients. A significant correlation was found between CAV-1 mRNA expression levels in VAT and different circulating inflammatory markers such as sialic acid (SA) (P < 0.001) and fibrinogen (P < 0.001) as well as with MCP1 mRNA expression (P < 0.05). CONCLUSION: Our findings show for the first time the upregulation of mRNA CAV-1 expression levels in VAT and SAT of obese NG and obese T2DM patients compared with lean controls, suggesting a role for CAV-1 in obesity and T2DM development. The association with different inflammatory markers further suggests an implication of CAV-1 in the low-grade inflammation accompanying obesity

Growth variability and demographic structure of northeast Atlantic chub mackerel (Scomber colias) in southern European Atlantic waters

The Atlantic chub mackerel (Scomber colias) is one of the main fishing resources for the fisheries targeting small pelagics in NW African waters. This species is expanding its geographical distribution through higher latitudes in southern European Atlantic waters, and it has become an important fishing resource in Iberian Atlantic waters during the last decades. The present study addresses the growth variability of S. colias in the Iberian waters, from southern Bay of Biscay up to Gulf of Cadiz. Age estimates based on otoliths and growth parameters were obtained from specimens collected within the study area during one decade (from both commercial landings and scientific-acoustic surveys), and sexual growth variation was analysed. A common pattern of abundant cohorts was observed in various areas. However, differences in the demographic structure of the catches were observed among the different areas, with the southernmost area studied (Portuguese and Spanish waters off Gulf of Cadiz) standing out with younger individuals. These new findings are of interest for the stock assessment of S. colias, which has not been addressed in ICES waters so far

Increased circulating and visceral adipose tissue expression levels of YKL-40 in obesity-associated type 2 diabetes are related to inflammation: impact of conventional weight loss and gastric bypass

Context: Plasma YKL-40 is elevated in patients with type 2 diabetes. The potential role of visceral adipose tissue (VAT) as a significant source of YKL-40 is unknown. Objective: In the study circulating and expression levels of YKL-40 were examined in VAT analyzing the contribution of adipocytes and stromovascular fraction cells (SVFCs).Wealso explored YKL-40’s implication in insulin resistance and inflammation and the effect of weight loss on plasma YKL-40 concentrations. PatientsandMethods: Samples obtained from 53 subjects were used in the study.Geneandprotein expression levels of YKL-40 were analyzed in VAT as well as in both adipocytes and SVFCs. In addition, circulating YKL-40 concentrations were measured before and after weight loss achieved either by Roux-en-Y gastric bypass (n 26) or after a conventional dietetic program (n 20). Results: Circulating concentrations and VAT expression of YKL-40 were increased in obese patients with type 2 diabetes (P 0.01) as well as associated with variables of insulin resistance and inflammation. No differences in YKL-40 expression levels between adipocytes and SVFCs were detected. Monocyte chemoattractant protein-1 and homeostasis model assessment emerged (P 0.01) as independent factors predicting circulating YKL-40. Elevated levels of YKL-40 in obese patients decreased after weight loss following a conventional hypocaloric diet (P 0.05) but not via a surgery-induced negative energy balance mediated by the Roux-en-Y gastric bypass. Conclusions: The association of increased YKL-40 mRNA and protein levels in VAT with its circulating concentrations indicates an important contribution of VAT in YKL-40 regulation. Furthermore, our data suggest a relevant role of glucose metabolism and inflammation on YKL-40 regulation

INIBIÇÃO DA INFECÇÃO in vitro DE MACRÓFAGOS POR Leishmania amazonensis POR EXTRATO E FRAÇÕES DE Chenopodium ambrosioides L.

A utilização de espécies vegetais, como Chenopodium ambrosioides L., para o tratamento da leishmaniose na terapêutica tradicional tem despertado interesse na busca de novos compostos mais eficazes e menos tóxicos. Nosso grupo demonstrou as atividades imunoestimuladora e anti-Leishmania in vivo do extrato bruto hidroalcoólico (EBH) de C. ambrosioides e efeito anti-promastigota in vitro do EBH e das suas frações. Neste trabalho, avaliou-se a atividade anti-Leishmania do EBH e suas frações acetato de etila (FAc) e clorofórmica (FCHCl3) em macrófagos infectados in vitro por Leishmania amazonensis. Foram realizados dois modelos: “proflático” e “terapêutico”. No primeiro, macrófagos peritoneais de camundongos Swiss  foram tratados com EBH, FAc ou FCHCl3 nas concentrações de 62,5µg/mL, 125µg/mL e 250µg/mL e, após 4 horas, infectados com formas promastigotas do parasito na razão de 1:10 por 24 horas. No segundo, os macrófagos foram infectados com promastigotas (1:10) e, após 4 horas, tratados com EBH, FAc ou FCHCl3 por 24 horas. Foram então realizados a quantifcação das amastigotas fagocitadas e o cálculo das taxas de infecção. No modelo “proflático”, apenas os macrófagos expostos ao EBH nas maiores concentrações apresentaram  taxas de  infecção  inferiores ao controle negativo. Entretanto, no modelo “terapêutico”, as  três concentrações de EBH e também da FAc reduziram a infecção de macrófagos em relação ao controle negativo, sendo a maior concentração do EBH mais efetiva inclusive que o controle positivo.  Em conclusão, o EBH de folhas de C. ambrosioides e a sua FAc possuem efeito terapêutico anti-Leishmania na infecção in vitro de macrófagos.Descritores: Leishmaniose; Leishmania amazonensis; Chenopodium ambrosioides.AbstractInhibit  of  in  vitro  macrophage  infection  by  Leishmania  amazonensis  by  extract  and  fractions  from Chenopodium ambrosioides L. The use of plant species such as Chenopodium ambrosioides L. for the treatment of leishmaniasis in traditional medicine has aroused interest in fnding new, more effective and less toxic compounds. Our group demonstrated the immunostimulatory and in vivo anti-Leishmania activities of the crude hydroalcoholic extract (HCE) from C. ambrosioides L. and the in vitro anti-promastigote effect of the HCE and its fractions. In this study, we evaluated the anti-Leishmania activity of the HCE and its fractions ethyl acetate (FAc) and chloroform (FCHCl3) in macrophages infected in vitro with Leishmania amazonensis. Two models, “prophylactic” and “therapeutic”, were performed. In the frst, Swiss mice peritoneal macrophages were treated with CHE, FAc or FCHCl3 in concentrations of 62,5μg/mL, 125μg/mL and 250μg/mL and, after 4 hours, infected with promastigote forms in the ratio of 1:10 for 24 hours. In the second model, the macrophages were infected with promastigotes (1:10)  and,  after 4 hours,  treated with HCE, FAc or FCHCl3 for 24 hours. Quantifcation of phagocytosed amastigotes and calculation  of  infection  rates were  then  perfomed.  In  the  “prophylactic” model,  only macrophages  exposed  to  the  highest concentrations of HCE presented  infection  rates  lower  than  the negative  control. However,  in  the  “therapeutic” model,  the three concentrations of both the HCE and FAc reduced the infection of macrophages compared to the negative control, with the highest concentration of HCE being even more effective than the positive control. In conclusion, the HCE from leaves of Chenopodium ambrosioides and its FAc have an anti-Leishmania therapeutic effect on the in vitro macrophages infection.Descriptors: Leishmaniasis. Leishmania amazonensis. Chenopodium ambrosioides

Plasma osteopontin levels and expression in adipose tissue are increased in obesity

Obesity acts as a cardiovascular risk factor by mechanisms that are not fully understood. Osteopontin (OPN) is a proinflammatory mediator involved in tissue remodeling that plays a role in atherosclerosis and diabetes. OBJECTIVE: The aim of the present study was to compare the circulating concentrations of OPN and its mRNA expression in omental adipose tissue of lean, overweight, and obese individuals and to analyze the effect of weight loss. SUBJECTS AND METHODS: Plasma concentrations of OPN were measured in 77 volunteers. OPN mRNA expression in omental adipose tissue obtained from 12 women was quantified by real-time PCR. In addition, the concentrations of OPN in 12 obese men were measured before and after weight loss following a dietetic program. SETTING: The study was conducted at a University Hospital. RESULTS: Obese and overweight patients exhibited significantly increased circulating OPN concentrations as compared with lean subjects (obese 72.6 +/- 28.5, overweight 68.2 +/- 20.8, lean 42.7 +/- 27.9 ng/ml; P < 0.001). A significant positive correlation was found between OPN levels and body fat (r = 0.45; P < 0.0001). Obese individuals showed significantly increased (P < 0.05) mRNA expression of OPN in omental adipose tissue as compared with lean volunteers, which was further increased in obese diabetic patients. Diet-induced weight loss significantly decreased OPN concentrations from 64.7 +/- 22.1 to 36.6 +/- 20.1 ng/ml (P = 0.006). CONCLUSIONS: These findings represent the first observation that plasma OPN and mRNA expression of OPN in omental adipose tissue are increased in overweight/obese patients with the latter being further elevated in obesity-associated diabetes. Moreover, weight loss reduces OPN concentrations, which may contribute to the beneficial effects accompanying weight reduction. Measurement of OPN might be useful for evaluating the outcomes of various clinical interventions for obesity-related cardiovascular disease

Increased tenascin C and Toll-like receptor 4 levels in visceral adipose tissue as a link between inflammation and extracellular matrix remodeling in obesity

CONTEXT: Obesity is associated with an altered inflammatory and extracellular matrix (ECM) profile. Tenascin C (TNC) is an ECM glycoprotein with proinflammatory effects. OBJECTIVE: We aimed to explore the expression levels of TNC in adipose tissue analyzing the contribution of adipocytes and stromovascular fraction cells (SVFC) as well as its impact on inflammation and ECM regulation. We also analyzed the effect of the stimulation with TNF-α and lipopolysaccharide (LPS) on both SVFC and adipocytes. PATIENTS AND METHODS: Samples obtained from 75 subjects were used in the study. Expression levels of TNC, TLR4, MMP2, and MMP9 were analyzed in visceral adipose tissue (VAT) as well as in both adipocytes and SVFC. In addition, Tnc expression was measured in two mice models of obesity. RESULTS: We show, for the first time, that VAT expression levels of TNC are increased in normoglycemic and type 2 diabetic obese patients (P<0.01) as well as in obese patients with nonalcoholic steatohepatitis (P<0.01). Furthermore, expression levels of Tnc in epididymal adipose tissue from two different mice models of obesity were significantly increased (P<0.01). TNC and TLR4 were mainly expressed by SVFC, and its expression was significantly enhanced (P<0.01) by TNF-α treatment. LPS treatment also increased mRNA levels of TNC. Moreover, the addition of exogenous TNC induced (P<0.05) TLR4 and CCL2 mRNA expression in human adipocyte cultures. CONCLUSIONS: These findings indicate that TNC is involved in the etiopathology of obesity via visceral adipose tissue inflammation representing a link with ECM remodeling