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Introduction: Cryptocurrencies have been attracting the attention from media, investors, regulators and academia during the last years. In spite of some scepticism in the financial area, cryptocurrencies are a relevant subject of academic research. Objectives: In this paper, several tools are adopted as an instrument that can help market agents and investors to more clearly assess the cryptocurrencies price dynamics and, thus, guide investment decisions more assertively while mitigating risks. Methods: We consider three methods, namely the Auto-Regressive Integrated Moving Average (ARIMA), Auto-Regressive Fractionally Integrated Moving Average (ARFIMA) and Detrended Fluctuation Analysis, and three indices given by the Hurst and Lyapunov exponents or the Fractal Dimension. This information allows assessing the behaviour of the time series, such as their persistence, randomness, predictability and chaoticity. Results: The results suggest that, except for the Bitcoin, the other cryptocurrencies exhibit the characteristic of mean reverting, showing a lower predictability when compared to the Bitcoin. The results for the Bitcoin also indicate a persistent behavior that is related to the long memory effect. Conclusions: The ARFIMA reveals better predictive performance than the ARIMA for all cryptocurrencies. Indeed, the obtained residual values for the ARFIMA are smaller for the auto and partial auto correlations functions, as well as for confidence intervals.
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The mechanisms of atrial fibrillation (AF) are a challenging research topic. The rotor hypothesis states that the AF is sustained by a reentrant wave that propagates around an unexcited core. Cardiac tissue heterogeneities, both structural and cellular, play an important role during fibrillatory dynamics, so that the ionic characteristics of the currents, their spatial distribution and their structural heterogeneity determine the meandering of the rotor. Several studies about rotor dynamics implement the standard diffusion equation. However, this mathematical scheme carries some limitations. It assumes the myocardium as a continuous medium, ignoring, therefore, its discrete and heterogeneous aspects. A computational model integrating both, electrical and structural properties could complement experimental and clinical results. A new mathematical model of the action potential propagation, based on complex fractional order derivatives is presented. The complex derivative order appears of considering the myocardium as discrete-scale invariant fractal. The main aim is to study the role of a myocardial, with fractal characteristics, on atrial fibrillatory dynamics. For this purpose, the degree of structural heterogeneity is described through derivatives of complex order γ = α + jß. A set of variations for γ is tested. The real part α takes values ranging from 1.1 to 2 and the imaginary part ß from 0 to 0.28. Under this scheme, the standard diffusion is recovered when α = 2 and ß = 0. The effect of γ on the action potential propagation over an atrial strand is investigated. Rotors are generated in a 2D model of atrial tissue under electrical remodeling due to chronic AF. The results show that the degree of structural heterogeneity, given by γ, modulates the electrophysiological properties and the dynamics of rotor-type reentrant mechanisms. The spatial stability of the rotor and the area of its unexcited core are modulated. As the real part decreases and the imaginary part increases, simulating a higher structural heterogeneity, the vulnerable window to reentrant is increased, as the total meandering of the rotor tip. This in silico study suggests that structural heterogeneity, described by means of complex order derivatives, modulates the stability of rotors and that a wide range of rotor dynamics can be generated.
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Polyphosphates have been found in all cell types examined to date and play diverse roles depending on the cell type. In eukaryotic organisms, polyphosphates have been investigated mainly in mammalian cells, and only a few studies have addressed arthropods. Pyrophosphatases have been shown to regulate polyphosphate metabolism. However, these studies were restricted to trypanosomatids. Here we focus on the tick Rhipicephalus microplus, a haematophagous ectoparasite that is highly harmful to cattle. We produced a recombinant R. microplus pyrophosphatase (rRmPPase) with the aim of investigating its kinetic parameters using polyphosphates as substrate. Molecular docking assays of RmPPase with polyphosphates were also carried out. The kinetic and Hill coefficient parameters indicated that rRmPPase has a greater affinity, higher catalytic efficiency and increased cooperativity for sodium phosphate glass type 15 (polyP15 ) than for sodium tripolyphosphate (polyP3 ). Through molecular docking, we found that polyP3 binds close to the Mg2+ atoms in the catalytic region of the protein, participating in their coordination network, whereas polyP15 interactions involve negatively charged phosphate groups and basic amino acid residues, such as Lys56, Arg58 and Lys193; polyP15 has a more favourable theoretical binding affinity than polyP3 , thus supporting the kinetic data. This study shows, for the first time in arthropods, a pyrophosphatase with polyphosphatase activity, suggesting its participation in polyphosphate metabolism.
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Proteínas de Artrópodes/genética , Pirofosfatase Inorgânica/genética , Polifosfatos/metabolismo , Rhipicephalus/genética , Animais , Proteínas de Artrópodes/metabolismo , Hidrólise , Pirofosfatase Inorgânica/metabolismo , Simulação de Acoplamento Molecular , Rhipicephalus/enzimologia , Rhipicephalus/metabolismoRESUMO
Objetivo: Exponer nuestra experiencia y evaluar la recurrencia en el manejo quirúrgico del angiofibroma nasal juvenil, abordaje abierto contra endoscópico, en el servicio de otorrinolaringología del noroeste del país. Materiales y métodos: Estudio observacional, retrospectivo, analítico. Se revisaron los expedientes clínicos de los pacientes con diagnóstico de angiofibroma nasal juvenil de 2014 a 2017, atendidos en el Servicio de Otorrinolaringología y Cirugía de Cabeza y Cuello de esta institución. Resultados: Un total de 19 pacientes con diagnóstico de angiofibroma nasal juvenil, fueron sometidos a un procedimiento quirúrgico, 14 abiertos y 5 endoscópicos, la recurrencia fue de 50 % y 40 % respectivamente, lo cual no fue estadísticamente significativo (p=0.88). No obstante, se contrastaron otras variables, como la necesidad de la Unidad de Cuidados Intensivos (UCI) para ambos grupos, 71 % en abordaje abierto y 20 % para el endoscópico, en lo cual si encontramos diferencia significativa (p=0.04). Conclusiones: El estudio no muestra una ventaja estadísticamente significativa del abordaje endoscópico frente al abordaje abierto, pero sí una menor necesidad de hospitalización en UCI, lo que reduciría los costos de atención.
Objective: To present our experience and assess the recurrence of juvenile nasopharyngeal angiofibroma after a surgical treatment (open versus endoscopic approach) in the country's northwestern Department of Otorhinolaryngology. Materials and methods: An observational, retrospective, analytical study. The medical records of patients diagnosed with juvenile nasopharyngeal angiofibroma, who were treated at the Department of Otorhinolaryngology - Head and Neck Surgery of this institution from 2014 to 2017, were reviewed. Results: A total of 19 patients diagnosed with juvenile nasopharyngeal angiofibroma underwent a surgical procedure, out of which 14 had an open surgery and 5 an endoscopic one. Recurrence accounted for 50 % and 40 %, respectively, which was not statistically significant (p = 0.88). However, other variables were compared, such as the need for admission to the Intensive Care Unit (ICU), which was represented by 71 % in the case of the open approach and 20 % for the endoscopic approach, where a significant difference was found (p = 0.04). Conclusions: The study shows no statistically significant advantage of the endoscopic approach versus the open approach, but demonstrates less need for ICU admissions, which would reduce healthcare costs.
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AIMS: To study the marked resistance of Periplaneta americana to entomopathogenic Metarhizium anisopliae. METHODS AND RESULTS: The low susceptibility of 4th instar nymphs applied topically with conidia seemed to be related to an active removal of conidia by the cockroach and to a disabled or retarded germination and subsequent development of conidia on the cuticle (up to 80% germination in the next 7 days after application). Inhibitions or delays of germination were related to the composition of the epicuticular fatty acids (30·1% w/w oleic, 28·3% w/w linoleic, 24·5% w/w palmitic and 11·7% w/w stearic acid) reported here. Propagules invading the nymphs through the cuticle took at least 3 days to reach the haemocoel, and no propagules were found after day 8 post-treatment. Strain IP 46 infected >50% of nymphs treated with doses ≥2 × 104 hyphal bodies (HB) nymph-1 and reduced the survival of nymphs ≤50%. Most nymphs (>70%) survived after injection of 6 × 103 and 2 × 103 HB nymph-1 . CONCLUSIONS: Findings emphasize a distinct resistance of nymphs of the American cockroach to infections by M. anisopliae. SIGNIFICANCE AND IMPACT OF THE STUDY: Our findings provide support for the development of biological control of this synanthropic cockroach pest.
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Metarhizium , Periplaneta/microbiologia , Controle Biológico de Vetores , Animais , Ácidos Graxos/química , Ninfa/química , Ninfa/microbiologia , Periplaneta/química , Periplaneta/crescimento & desenvolvimento , Esporos FúngicosRESUMO
The rat models currently employed for studies of nerve regeneration present distinct disadvantages. We propose a new technique of stretch-induced nerve injury, used here to evaluate the influence of gabapentin (GBP) on nerve regeneration. Male Wistar rats (300 g; n=36) underwent surgery and exposure of the median nerve in the right forelimbs, either with or without nerve injury. The technique was performed using distal and proximal clamps separated by a distance of 2 cm and a sliding distance of 3 mm. The nerve was compressed and stretched for 5 s until the bands of Fontana disappeared. The animals were evaluated in relation to functional, biochemical and histological parameters. Stretching of the median nerve led to complete loss of motor function up to 12 days after the lesion (P<0.001), compared to non-injured nerves, as assessed in the grasping test. Grasping force in the nerve-injured animals did not return to control values up to 30 days after surgery (P<0.05). Nerve injury also caused an increase in the time of sensory recovery, as well as in the electrical and mechanical stimulation tests. Treatment of the animals with GBP promoted an improvement in the morphometric analysis of median nerve cross-sections compared with the operated vehicle group, as observed in the area of myelinated fibers or connective tissue (P<0.001), in the density of myelinated fibers/mm2 (P<0.05) and in the degeneration fragments (P<0.01). Stretch-induced nerve injury seems to be a simple and relevant model for evaluating nerve regeneration.
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The rat models currently employed for studies of nerve regeneration present distinct disadvantages. We propose a new technique of stretch-induced nerve injury, used here to evaluate the influence of gabapentin (GBP) on nerve regeneration. Male Wistar rats (300 g; n=36) underwent surgery and exposure of the median nerve in the right forelimbs, either with or without nerve injury. The technique was performed using distal and proximal clamps separated by a distance of 2 cm and a sliding distance of 3 mm. The nerve was compressed and stretched for 5 s until the bands of Fontana disappeared. The animals were evaluated in relation to functional, biochemical and histological parameters. Stretching of the median nerve led to complete loss of motor function up to 12 days after the lesion (P<0.001), compared to non-injured nerves, as assessed in the grasping test. Grasping force in the nerve-injured animals did not return to control values up to 30 days after surgery (P<0.05). Nerve injury also caused an increase in the time of sensory recovery, as well as in the electrical and mechanical stimulation tests. Treatment of the animals with GBP promoted an improvement in the morphometric analysis of median nerve cross-sections compared with the operated vehicle group, as observed in the area of myelinated fibers or connective tissue (P<0.001), in the density of myelinated fibers/mm2 (P<0.05) and in the degeneration fragments (P<0.01). Stretch-induced nerve injury seems to be a simple and relevant model for evaluating nerve regeneration.
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Toll-like receptors (TLRs) play an important role in several inflammatory diseases such as diabetes. The present study was to determine whether hyperglycemia in diabetes interferes in reactive oxygen species (ROS) production in granulocytes stimulated with either TLR2/zymosan, TLR4/lipopolysaccharide (LPS) or TLR2,4,9/concanavalin A (ConA). NADPH (nicotinamide adenine dinucleotide phosphate) oxidase and mitogen-activated protein kinase (MAPK) signaling pathways associated with ROS generation in TLR-stimulated granulocytes were evaluated. Our results demonstrate that ROS generation in resting granulocytes derived from patients suffering from Type 2 diabetes mellitus (T2DM) is significantly higher than that observed in equivalent cells from healthy controls. However, ROS formed by TLR-stimulated granulocytes from T2DM patients and healthy subjects were comparable. ROS production by TLR4,9 depends on NADPH-oxidase and MAPK signaling pathways. In contrast, the activation of TLR2 leads to ROS production by a mechanism that is dependent on NADPH oxidase but independent of the MAPK. In conclusion our results suggest that hyperglycemia in diabetes may prime cells metabolically for ROS generation but does not exert any significant effect on TLR-stimulated ROS production and possibly does not aggravate the development of ROS-dependent diabetic complications.
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Diabetes Mellitus Tipo 2/metabolismo , Granulócitos/metabolismo , Hiperglicemia/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Receptores Toll-Like/metabolismo , Adulto , Idoso , Idoso de 80 Anos ou mais , Células Cultivadas , Concanavalina A/farmacologia , Feminino , Granulócitos/efeitos dos fármacos , Humanos , Lipopolissacarídeos/farmacologia , Masculino , Pessoa de Meia-Idade , Proteínas Quinases Ativadas por Mitógeno/metabolismo , NADPH Oxidases/metabolismo , Zimosan/farmacologiaRESUMO
OBJECTIVE: To investigate the effects of rosiglitazone, a peroxisome proliferator-activated receptor-γ agonist, on the secretion of vascular endothelial growth factor (VEGF) by peripheral blood mononuclear cells (PBMCs) and on the generation of reactive oxygen species (ROS) by leukocytes. METHODS: PBMCs and leukocytes were obtained from venous blood samples collected from 20 healthy individuals. VEGF secretion was evaluated using a commercial ELISA kit, while ROS production was determined using a luminol-dependent chemiluminescence assay. RESULTS: Rosiglitazone and calphostin C (a protein kinase C inhibitor) inhibited VEGF secretion by PBMCs by 63.7 and 62.3%, respectively. Both agents reduced ROS production in non-stimulated human leukocytes and down-regulated the enhanced generation of ROS in leukocytes that had been stimulated with the PKC activator phorbol 12,13-dibutyrate. CONCLUSION: The results support the involvement of PKC as a direct, and/or NADPH-oxidase as an indirect, target for the action of rosiglitazone on VEGF secretion by PBMCs and ROS production in human leukocytes.
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Leucócitos Mononucleares/citologia , PPAR gama/metabolismo , Tiazolidinedionas/farmacologia , Fator A de Crescimento do Endotélio Vascular/metabolismo , Adulto , Humanos , Hipoglicemiantes/farmacologia , Leucócitos/citologia , Luminescência , Pessoa de Meia-Idade , Naftalenos/farmacologia , Dibutirato de 12,13-Forbol/metabolismo , Proteína Quinase C/metabolismo , Espécies Reativas de Oxigênio , RosiglitazonaRESUMO
Verificaram-se os efeitos da associação de furosemida e fenilbutazona sobre variáveis hidroeletrolíticas de cavalos antes e após a corrida. Dezenove equinos foram distribuídos em três grupos, de acordo com os protocolos de tratamento. O primeiro grupo, de cinco animais, não recebeu medicação (grupo-controle); o segundo grupo, de sete animais, foi tratado com furosemida, na dose de 1mg/kg, por via intramuscular, até quatro horas antes do páreo; o terceiro, de sete animais, recebeu furosemida, por via intramuscular, e fenilbutazona, por via intravenosa, nas doses de 1,0 e 4,4mg/kg, respectivamente, até quatro horas antes da corrida. Amostras de sangue foram colhidas antes, imediatamente após e duas horas após o páreo, para avaliação da osmolalidade plasmática e das concentrações plasmáticas de sódio, potássio e cloreto. A utilização de furosemida e da associação furosemida e fenilbutazona até 4h antes dos páreos nas dosagens descritas alterou (P<0,05) a osmolalidade plasmática dos equinos, mas não alterou (P>0,05) as concentrações de sódio, potássio e cloreto. Os páreos alteraram de forma fisiológica a osmolalidade plasmática e a concentração sanguínea de K+ devido ao exercício de alta intensidade.
The objective of this study was to verify the effects of furosemide and phenylbutazone association on fluid and electrolyte balance characteristics of horses before and after a race. Nineteen horses were divided into three groups according to treatment protocols. The first group (five animals - control) was not medicated. A second group (seven animals) was treated with furosemide (1mg/kg, intramuscular up to four hours before the race). A third group (seven animals) received furosemide (1mg/kg) and phenylbutazone (4.4mg/kg), both intramuscular, up to four hours before race. Blood samples were collected before, immediately after and two hours after a race to evaluate the plasma osmolality and sodium, potassium and chloride concentrations. The use of furosemide and furosemide plus phenylbutazone up to four hours before the race altered (P<0.05) the plasma osmolality but did not change (P>0.05) the sodium, potassium and chloride concentrations. It was not possible to determine an antagonist effect of phenylbutazone on furosemide, based on fluid and electrolyte balance. Due to the high intensity exercise, the increase in plasma osmolality and potassium concentration was attributed to the race effect.
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Animais , Eletrólitos/metabolismo , Fenilbutazona/administração & dosagem , Furosemida/administração & dosagem , Concentração Osmolar , Cavalos/metabolismo , Potássio , SódioRESUMO
Verificaram-se os efeitos da associação de furosemida e fenilbutazona sobre variáveis hidroeletrolíticas de cavalos antes e após a corrida. Dezenove equinos foram distribuídos em três grupos, de acordo com os protocolos de tratamento. O primeiro grupo, de cinco animais, não recebeu medicação (grupo-controle); o segundo grupo, de sete animais, foi tratado com furosemida, na dose de 1mg/kg, por via intramuscular, até quatro horas antes do páreo; o terceiro, de sete animais, recebeu furosemida, por via intramuscular, e fenilbutazona, por via intravenosa, nas doses de 1,0 e 4,4mg/kg, respectivamente, até quatro horas antes da corrida. Amostras de sangue foram colhidas antes, imediatamente após e duas horas após o páreo, para avaliação da osmolalidade plasmática e das concentrações plasmáticas de sódio, potássio e cloreto. A utilização de furosemida e da associação furosemida e fenilbutazona até 4h antes dos páreos nas dosagens descritas alterou (P<0,05) a osmolalidade plasmática dos equinos, mas não alterou (P>0,05) as concentrações de sódio, potássio e cloreto. Os páreos alteraram de forma fisiológica a osmolalidade plasmática e a concentração sanguínea de K+ devido ao exercício de alta intensidade.(AU)
The objective of this study was to verify the effects of furosemide and phenylbutazone association on fluid and electrolyte balance characteristics of horses before and after a race. Nineteen horses were divided into three groups according to treatment protocols. The first group (five animals - control) was not medicated. A second group (seven animals) was treated with furosemide (1mg/kg, intramuscular up to four hours before the race). A third group (seven animals) received furosemide (1mg/kg) and phenylbutazone (4.4mg/kg), both intramuscular, up to four hours before race. Blood samples were collected before, immediately after and two hours after a race to evaluate the plasma osmolality and sodium, potassium and chloride concentrations. The use of furosemide and furosemide plus phenylbutazone up to four hours before the race altered (P<0.05) the plasma osmolality but did not change (P>0.05) the sodium, potassium and chloride concentrations. It was not possible to determine an antagonist effect of phenylbutazone on furosemide, based on fluid and electrolyte balance. Due to the high intensity exercise, the increase in plasma osmolality and potassium concentration was attributed to the race effect.(AU)
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Animais , Furosemida/administração & dosagem , Fenilbutazona/administração & dosagem , Eletrólitos/metabolismo , Concentração Osmolar , Sódio , Potássio , Cavalos/metabolismoRESUMO
AIM: The present study investigates the interaction of TLR4 and RAGE with their respective ligands as inducers of the inflammatory markers IL-6 and TNF-α. Also, the reactivity of peripheral blood mononuclear cells (PBMNC) from type 2 diabetic (T2D) patients and non-diabetic healthy controls (ND) were comparatively studied. METHODS: Concentrations of IL-6 and TNF-α were measured by sandwich Elisa, using kits supplied by Assay Designs (Ann Arbor, MI, USA). PBMNC from T2D and ND were incubated in the presence or absence of LPS, anti-TLR4 or anti-RAGE for 72 hours at 37°C under 5% CO(2). The final volume was adjusted to 300 µL in DMEM supplemented with 10% fetal bovine serum. After incubation, the cells were centrifuged, the supernatant collected and the cytokines measured. RESULTS: PBMNC from T2D were more sensitive to innate immune stimulation with LPS and monoclonal agonist anti-TLR4 than were cells from ND. The actions of LPS, anti-TLR4 and anti-RAGE potentiated the production of IL-6 and TNF-α in both groups. The simultaneous activation of monoclonal anti-RAGE and anti-TLR4 suggests that both antibodies used different receptors on the cell surface, but converged on the same PBMNC signaling metabolic pathways. This simultaneous activation induced a higher production of IL-6 and TNF-α in PBMNC from the T2D patients than from the ND subjects. CONCLUSION: Our results clearly show an exacerbation of innate immunity in PBMNC with T2D that was possibly hyperglycaemia-induced. These data, when analyzed together, suggest the importance of innate immunity in the pathogenesis of T2D.
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Diabetes Mellitus Tipo 2/metabolismo , Inflamação/metabolismo , Receptor para Produtos Finais de Glicação Avançada/metabolismo , Receptor 4 Toll-Like/metabolismo , Adulto , Idoso , Idoso de 80 Anos ou mais , Anticorpos Monoclonais/imunologia , Anticorpos Monoclonais/farmacologia , Estudos de Casos e Controles , Diabetes Mellitus Tipo 2/sangue , Humanos , Interleucina-6/biossíntese , Leucócitos Mononucleares/efeitos dos fármacos , Leucócitos Mononucleares/metabolismo , Lipopolissacarídeos/farmacologia , Pessoa de Meia-Idade , Receptor para Produtos Finais de Glicação Avançada/imunologia , Transdução de Sinais/efeitos dos fármacos , Receptor 4 Toll-Like/agonistas , Receptor 4 Toll-Like/antagonistas & inibidores , Receptor 4 Toll-Like/imunologia , Fator de Necrose Tumoral alfa/biossínteseRESUMO
In the last decade ostrich farms spread throughout the world as an alternative source of investment. Although previous studies have reported hematology and biochemical values for ostriches from several regions of the world, little information is available regarding leukocyte morphology. This study reports the morphology and ultrastructure of ostrich leukocytes and hematology and biochemical values from birds raised in Brazil. Heterophils presented a lobulated nucleus, and fusiform, and acidophilic and peroxidase-negative granules. Ultrastructurally, 2 kinds of cytoplasmic granules were observed: one was large and fusiform and the other smaller with heterogeneous morphology and electrondensity; granules were peroxidase-negative. Eosinophils had a kidney-shaped eccentrically placed nucleus that was rarely lobulated and eosinophilic, round, and peroxidase-positive granules. At the ultrastructure level, 2 main kinds of granules with the same size and form but different electron density were seen; granules were peroxidase-positive. Lymphocytes and thrombocytes had the same characteristics of other avian species; monocytes presented morphological heterogeneity. Hematological and serum biochemical profiles had no sex influence and were established for ostriches raised in southeastern Brazil. These parameters will help the diagnosis of specific ostrich pathologies and serve as basic knowledge for studies in immunology and comparative avian pathology.
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Leucócitos/ultraestrutura , Struthioniformes/sangue , AnimaisRESUMO
OBJECTIVE: To compare the role of Akt/PKB signaling pathway in the modulation of reactive oxygen species (ROS) production by autologous plasma in peripheral blood mononuclear cells (PBMNC) from type 2 diabetic patients and healthy subjects. MATERIALS AND METHODS: This study was approved by Santa Casa Ethical Committee and has included patients diagnosed with diabetes type 2 (DM2) and control group (non-diabetic) (ND). PBMNC were purified utilizing Ficoll-hypaque gradient. ROS was quantified by luminol-dependent chemiluminescence. The Akt/PKB phosphorylation was measured using a CASE kit. Statistical analyses were made with t Student test and chi-square (chi(2)). p<0.05 was considered significant. RESULTS: 12, 13-Phorbol dibutyrate (PDB) stimulated the production of higher levels of ROS in PBMNC from type 2 diabetic patients than that from healthy subjects. Autologous plasma, however, inhibited induced or not ROS production in PBMNC in both groups. The inhibition of PBMNC-ROS derived by autologous plasma from healthy subjects was higher than that from type 2 diabetic patients. Plasma phosphorylated (activated) Akt/PKB. The percentage of phosphorylation induced by autologous plasma in PBMNC from patients and healthy control were 14% and 93%, respectively. Inhibition of ROS production in PBMNC from DM2 were similar for PBMNC+plasma; PBMNC+Akti; and PBMNC+plasma+Akti. However, in ND control, plasma showed a higher ROS inhibition than Akti or plasma plus Akti. CONCLUSIONS: Our results suggest that the low antioxidant capacity observed in autologous plasma from DM2 patients in conjunction with the decreased activation of PKB may cause an imbalance in the oxidizing/reducing responses, possible inducing an oxidative stress state, which could be associated with tissular damage.
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Diabetes Mellitus Tipo 2/metabolismo , Leucócitos/metabolismo , Proteínas Proto-Oncogênicas c-akt/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Transdução de Sinais , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , Leucócitos/efeitos dos fármacos , Pessoa de Meia-Idade , NADPH Oxidases/metabolismo , Fosforilação , Proteína Quinase C/metabolismo , Proteínas Proto-Oncogênicas c-akt/antagonistas & inibidoresRESUMO
BACKGROUND: Granulocytes from healthy subjects and from patients suffering from diabetes mellitus present differences in reactivity to stimulation with cyclic nucleotide-elevating agents. The production of reactive oxygen species (ROS) is inhibited in cells from non-diabetic subjects following such stimulation, but activated through a PKA-independent signaling pathway in granulocytes from type 1 and type 2 diabetic patients. The aim of the present study was to understand better the changes in signaling mechanisms induced by the disease. METHODS: ROS production in granulocytes from healthy subjects and from type 1 and type 2 diabetic patients was measured using a luminol-dependent chemiluminescence assay. Granulocytes were stimulated by the addition of the cAMP-elevating agent dibutyryl cAMP. In some experiments, granulocytes were pre-treated with an inhibitor of PKA or Akt/PKB prior to cAMP stimulation. RESULTS: Intracellular elevation of cAMP induced a PKA-dependent and Akt/PKB-independent inhibition of ROS production in granulocytes from healthy subjects, but a significant activation in cells from both type 1 and type 2 diabetic patients. Most significantly, activation of ROS generation in cells from diabetic patients was shown to be Akt/PKB-dependent and PKA-independent. CONCLUSIONS: These results suggest that chronic hyperglycaemia could induce metabolic adaptation in cAMP-related signaling mechanisms. Epac (exchange protein directly activated by cAMP) is a novel cAMP receptor besides PKA involved in different signaling pathways. The cAMP-stimulated inverse ROS response in granulocytes from type 1 and type 2 diabetic patients may be due to a change in signaling pathways from cAMP/PKA to cAMP/Epac/Akt/PKB. These preliminary results require further studies in order to evaluate their consequences on innate immunity and pathogenesis of diabetes mellitus.
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Bucladesina/farmacologia , AMP Cíclico/sangue , Diabetes Mellitus Tipo 1/sangue , Diabetes Mellitus Tipo 2/sangue , Granulócitos/metabolismo , Proteínas Proto-Oncogênicas c-akt/sangue , Espécies Reativas de Oxigênio/sangue , Adulto , Feminino , Granulócitos/efeitos dos fármacos , Humanos , Masculino , Proteínas Proto-Oncogênicas c-akt/efeitos dos fármacos , Valores de ReferênciaRESUMO
UNLABELLED: SUMMARY-BACKGROUND: The present study investigates the hypothesis that cells from ill patients and from healthy subjects may have different reactivity under metabolic stimulation as a consequence of an disease-induced metabolic adaptation. METHODS: Granulocytes either from healthy subjects or from type II-Non Insulin Dependent Diabetes Mellitus (NIDDM) patients were compared in their capacities to generate Reactive Oxygen Species (ROS). The ROS generation was comparatively determined in a chemiluminescence assay, luminol-dependent, after cell incubation in the presence of either cyclic AMP - elevating agents or Interleukin 10. In some experiments the cells were pretreated with H89 compound (a PKA inhibitor) or with diphenylene iodonium (DPI), a NADPH-oxidase inhibitor. RESULTS: Our results showed an increased ROS generation in granulocytes from diabetic patients in absence of cyclic AMP-elevating agents or IL-10. In the presence of cyclic AMP-elevating agents was observed an inverse metabolic response in granulocytes from diabetic patients in comparison to cells from healthy subjects. The granulocytes were pre-incubated in the presence of cyclic AMP-elevating agents--amminophylline (AMF) or dibutyryl cyclic AMP (dbcAMP)--or interleukin 10 (IL-10). The AMF, dbcAMP and IL-10 inhibited ROS production by granulocytes from healthy subjects. By contrast, AMF and dbcAMP activated cells from diabetic patients while IL-10 had no effect. The inhibition of ROS induced by AMF, dbcAMP or IL-10 was promptly abolished by the pretreatment of the cells with either PKA H89 inhibitor or NADPH-oxidase inhibitor (DPI) in granulocytes from healthy subjects. In relation to the granulocytes from type 2 diabetics patients, the activation of ROS generation mediated by AMF and dbcAMP was fully abolished by NADPH-oxidase DPI-inhibitor, but not by PKA H89 inhibitor. CONCLUSIONS: Our present results reinforce the hypothesis that cells from ill patients (type II diabetic) when compared to cells from healthy subjects have different reactivity under metabolic stimulation. ROS production by human granulocytes was modulated by cyclic AMP elevating agents and IL-10. The inhibition of the ROS production in cells from healthy subjects was PKA-dependent while the activation in granulocytes from patients was PKA-independent. This inverse metabolic response, in cells from patients, suggests the use of an alternative metabolic pathway PKA-independent, possible cAMP/Epac/PKB-dependent. The correlation between activation of ROS production in granulocytes from diabetic patients and pathogenesis of diabetes can be suggested, however, further and extensive studies are needed for demonstrating this suggestion.
Assuntos
Proteínas Quinases Dependentes de AMP Cíclico/sangue , AMP Cíclico/metabolismo , Diabetes Mellitus Tipo 2/sangue , Granulócitos/metabolismo , Interleucina-10/farmacologia , Espécies Reativas de Oxigênio/metabolismo , Sulfonamidas , Idoso , Aminofilina/farmacologia , Bucladesina/farmacologia , Proteína Quinase Tipo II Dependente de AMP Cíclico , Proteínas Quinases Dependentes de AMP Cíclico/antagonistas & inibidores , Inibidores Enzimáticos/farmacologia , Feminino , Granulócitos/efeitos dos fármacos , Granulócitos/imunologia , Humanos , Isoquinolinas/farmacologia , Masculino , Pessoa de Meia-Idade , Valores de ReferênciaRESUMO
BACKGROUND: The present study was designed to investigate the hypothesis that cells from ill patients and from healthy subjects may have different reactivities under metabolic stimulation. METHODS: The study was performed with granulocytes from non-diabetic subjects and from type II -Non Insulin Dependent Diabetes mellitus (NIDDM) patients. The nitric oxide (NO) generation was comparatively determined by the nitrite concentration (micromolar of nitrite) after cell incubation in the presence of cyclic nucleotide-elevating agents. RESULTS: Our results showed an inverse reactivity for granulocytes from diabetic patients when compared to non-diabetic subjects. Granulocytes were incubated in the presence of drugs that elevate the intracellular level of cyclic AMP aminophylline (AMF), dibutyryl cyclic AMP (dbcAMP)], cyclic GMP [8.Br. cyclic GMP(8.Br.cGMP) or levamisole (LEV)]. The cyclic AMP-elevating agents (AMF and d bcAMP) inhibited NO production by granulocytes from non-diabetic subjects and activated cells from diabetic patients. By contrast, cyclic GMP-elevating agents (8.Br.cGMP and LEV) activated cells from non-diabetic subjects and inhibited granulocytes from diabetic patients. The activation of NO generation by cyclic nucleotides was blocked by pretreatment of granulocytes with L-NAME. CONCLUSION: The authors describe for the first time that both cyclic AMP and cyclic GMP were able to modulate nitric oxide production in human granulocytes and that cell reactivity in ill patients (diabetic) showed altered and inverse response in comparison to granulocytes from healthy subjects. This inverse reactivity possibly reflects a disease-induced adapted metabolic response. The consequences of this altered metabolic response on host defense and inflammation may be speculated, but further experiments are needed to confirm this hypothesis.
Assuntos
8-Bromo Monofosfato de Adenosina Cíclica/farmacologia , AMP Cíclico/sangue , GMP Cíclico/análogos & derivados , GMP Cíclico/sangue , GMP Cíclico/farmacologia , Diabetes Mellitus Tipo 2/sangue , Granulócitos/metabolismo , Óxido Nítrico/sangue , Idoso , Feminino , Granulócitos/efeitos dos fármacos , Humanos , Masculino , Pessoa de Meia-Idade , NG-Nitroarginina Metil Éster/farmacologia , Nitritos/sangue , Valores de ReferênciaRESUMO
In this present paper the age-induced effect on reactive oxidizing species generated by oxygen (ROS) and nitrogen (RNS) was studied using human phagocyting granulocytes. The ROS and RNS were quantified, respectively, in a chemiluminescence assay and by the measurement of nitrite production. The age-induced reactive oxidizing species generation was studied in healthy subjects ranging from 20 to 80 years old, divided into six age groups: group I, 20-29 years old; group II, 30-39 years old; group III, 40-49 years old; group IV, 50-59 years old; group V, 60-69 years old; and group VI, 70-80 years old. Our results demonstrate a parallelism between generation of the ROS and RNS induced by the age. A significant increase of ROS production was observed from 40 years old (age groups III, IV, V and VI while for RNS this increase was observed only from 50 years old (groups IV, V and VI). These data suggest an increase of oxidizing species generation (ROS/RNS) related to age. The increased generation of ROS (40-49 years old) was induced before the increasing of RNS (50-59 years old) and it may have consequences on inflammation and host defences.
Assuntos
Envelhecimento/metabolismo , Granulócitos/metabolismo , Nitritos/metabolismo , Fagocitose , Espécies Reativas de Oxigênio/metabolismo , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , Masculino , Pessoa de Meia-IdadeRESUMO
The biochemical processes linked up to cyclic nucleotides related to the phenomenon of phagocytosis in Biomphalaria glabrata hemocytes were studied. In hemocytes the results suggest the presence of a phagocytic capacity similar to that observed in human cells related to regulation by cyclic adenylate monophosphate (cAMP), but not by cyclic guanylate monophosphate (cGMP). This similarity and differences in the metabolic process of phagocytary capacity between human phagocytary cells and hemocytes could represent an interesting model aimed at studying the phylogenetic evolution of enzymatic complexes.
Assuntos
Biomphalaria/imunologia , AMP Cíclico/metabolismo , GMP Cíclico/metabolismo , Granulócitos/imunologia , Hemócitos/imunologia , Fagocitose , Aminofilina/farmacologia , Animais , Biomphalaria/parasitologia , AMP Cíclico/farmacologia , GMP Cíclico/farmacologia , Granulócitos/metabolismo , Hemócitos/metabolismo , Humanos , Schistosoma mansoni/imunologia , Zimosan/farmacologiaRESUMO
The respiratory burst reaction has been studied in human granulocytes from normal subjects divided in four age groups: (I) 20-29, (II) 30-39, (III) 40-49, and (IV) 50-59 years old. Zimosan opsonized particles (OZ) were used to evaluate, simultaneously, the reducing power and the oxidizing species generation. Our results showed a strong parallelism and a direct correlation between oxidizing species generation and reducing power in the groups (I) and (II), in presence or in the absence of opsonized zimosan. However, the age groups (III) and (IV) showed an increase in the free radicals generation and a significant decrease in the cellular reducing power. This inverse correlation observed between oxidizing/reducing power in the (III) and (IV) age groups may suggest a metabolic cellular disequilibrium.