RESUMEN
Pancreatic islet desensitization by high glucose concentrations is a temporary and reversible state of beta-cell refractoriness to glucose (and possibly other secretagogues), due to repeated or prolonged pre-exposure to increased glucose concentrations. We evaluated whether the oral antidiabetic agent metformin affects this phenomenon in isolated, human pancreatic islets, and whether the possible effects of the biguanide are influenced by the presence of a sulphonylurea, glyburide. Islets prepared from five human pancreases were incubated for 24 h in M199 culture medium containing either 5.5 or 22.2 mmol/l glucose, with or without a therapeutic concentration (2.4 microg/ml) of metformin. Then, the islets were challenged with either 3.3 mmol/l glucose, 16.7 mmol/l glucose, or 3.3 mmol/l glucose + 10 mmol/l arginine, and insulin release was measured. After incubation in the absence of metformin, the human islets exposed to 22.2 mmol/l glucose showed no significant increase in insulin release when challenged with 16.7 mmol/l glucose (confirming that hyperglycemia desensitizes pancreatic beta-cells). In the presence of metformin, the islets fully maintained the ability to significantly increase their insulin release in response to glucose, even when previously exposed to 22.2 mmol/l glucose. No major effect on arginine-induced insulin release was observed, whatever the culture conditions. The protective action of metformin was observed also when glyburide was present in the incubation medium, whereas the sulphonylurea alone did not affect insulin release from the islets previously exposed to high glucose concentrations. These in vitro results suggest that metformin can prevent the desensitization of human pancreatic islets induced by prolonged exposure to increased glucose concentrations.
Asunto(s)
Glucosa/farmacología , Hipoglucemiantes/farmacología , Islotes Pancreáticos/efectos de los fármacos , Metformina/farmacología , Adolescente , Adulto , Arginina/farmacología , Biguanidas/farmacología , Cadáver , Relación Dosis-Respuesta a Droga , Femenino , Gliburida/farmacología , Humanos , Técnicas In Vitro , Insulina/metabolismo , Secreción de Insulina , Islotes Pancreáticos/metabolismo , Masculino , Persona de Mediana EdadRESUMEN
Isolated human pancreatic islets were prepared by collagenase digestion and density gradient purification, and the effects of glibenclamide (0.5 and 5.0 mumol/l) and metformin (20 and 200 mumol/l), alone or in combination, on insulin release were evaluated at varying glucose concentrations. At 3.3 mmol/l glucose level, the addition of 5.0 mumol/l glibenclamide or 5.0 mumol/l glibenclamide plus 200 mumol/l metformin caused a significant increase of insulin release, compared with glucose alone. At 16.7 mmol/l glucose concentration, a significant increase of insulin secretion, compared with glucose alone, was produced by the addition of either 5.0 mumol/l glibenclamide, 200 mumol/l metformin, or both 5.0 mumol/l glibenclamide and 200 mumol/l metformin. The effect of the combination of the two drugs was significantly higher than that with either drug used alone. Thus, glibenclamide was shown to have an insulinotropic effect on human islets at both low and high glucose concentrations, and metformin at high glucose concentrations. A possible synergistic effect of glibenclamide and metformin at high glucose concentrations is also suggested.
Asunto(s)
Gliburida/farmacología , Insulina/metabolismo , Islotes Pancreáticos/metabolismo , Metformina/farmacología , Separación Celular/métodos , Centrifugación por Gradiente de Densidad , Colagenasas , Humanos , Técnicas In Vitro , Secreción de Insulina , Islotes Pancreáticos/citología , Islotes Pancreáticos/efectos de los fármacosRESUMEN
We report a case of severe Legionnaires' disease (LD) complicated by a lung abscess in an immunocompetent patient who required ECMO therapy and thoracic surgery. The results of repeated Legionella quantitative real-time PCR performed on both sera and respiratory samples correlated with the LD severity and the poor clinical outcome. Moreover, the PCR allowed for the detection of Legionella DNA in the lung abscess specimen, which was negative when cultured for Legionella. This case report provides a logical basis for further investigations to examine whether the Legionella quantitative PCR could improve the assessment of LD severity and constitute a prognostic marker.
Asunto(s)
Supervivencia de Injerto , Trasplante de Islotes Pancreáticos/fisiología , Trasplante Heterólogo/fisiología , Animales , Bovinos , Células Cultivadas , Cromatografía Líquida de Alta Presión , Femenino , Insulina/sangre , Insulina/metabolismo , Secreción de Insulina , Islotes Pancreáticos/citología , Trasplante de Islotes Pancreáticos/métodos , Trasplante de Islotes Pancreáticos/patología , Porcinos , Timo , Trasplante Heterólogo/métodos , Trasplante Heterólogo/patología , Trasplante HeterotópicoAsunto(s)
Separación Celular/métodos , Islotes Pancreáticos/citología , Islotes Pancreáticos/fisiología , Animales , Glucemia/metabolismo , Cápsulas , Bovinos , Diabetes Mellitus Experimental/sangre , Diabetes Mellitus Experimental/cirugía , Técnicas In Vitro , Trasplante de Islotes Pancreáticos/fisiología , Ratones , Ratones Endogámicos BALB CAsunto(s)
Fármacos Gastrointestinales/toxicidad , Glucagón/toxicidad , Supervivencia de Injerto/efectos de los fármacos , Trasplante de Islotes Pancreáticos , Islotes Pancreáticos/efectos de los fármacos , Células Cultivadas , Diabetes Mellitus Tipo 1/cirugía , Glucagón/metabolismo , Humanos , Islotes Pancreáticos/metabolismoAsunto(s)
Islotes Pancreáticos/inmunología , Activación de Linfocitos , Células TH1/inmunología , Células Th2/inmunología , Animales , Bovinos , Células Cultivadas , Técnicas de Cocultivo , Humanos , Interferón gamma/biosíntesis , Interleucinas/biosíntesis , Islotes Pancreáticos/citología , Receptores de Interleucina-2/biosíntesis , Factores de Tiempo , Trasplante Heterólogo/inmunología , Trasplante Homólogo/inmunologíaAsunto(s)
Hormona Liberadora de Gonadotropina/uso terapéutico , Supervivencia de Injerto/efectos de los fármacos , Trasplante de Islotes Pancreáticos/fisiología , Islotes Pancreáticos/citología , Niacinamida/uso terapéutico , Trasplante Heterólogo/fisiología , Animales , Glucemia/metabolismo , Bovinos , Células Cultivadas , Diabetes Mellitus Experimental/sangre , Diabetes Mellitus Experimental/cirugía , Hormona Liberadora de Gonadotropina/farmacología , Insulina/metabolismo , Secreción de Insulina , Islotes Pancreáticos/efectos de los fármacos , Islotes Pancreáticos/metabolismo , Trasplante de Islotes Pancreáticos/inmunología , Trasplante de Islotes Pancreáticos/patología , Metilprednisolona/farmacología , Metilprednisolona/uso terapéutico , Niacinamida/farmacología , Ratas , Ratas Endogámicas Lew , Trasplante Heterólogo/inmunología , Trasplante Heterólogo/patologíaAsunto(s)
Insulina/metabolismo , Trasplante de Islotes Pancreáticos/fisiología , Islotes Pancreáticos/citología , Animales , Bovinos , Técnicas de Cultivo de Célula/métodos , Supervivencia Celular , Glucosa/farmacología , Supervivencia de Injerto , Secreción de Insulina , Islotes Pancreáticos/efectos de los fármacos , Islotes Pancreáticos/metabolismo , Ratones , Ratones Desnudos , Factores de Tiempo , Trasplante HeterólogoAsunto(s)
Trasplante de Islotes Pancreáticos/métodos , Trasplante Heterólogo/métodos , Trasplante Heterotópico/métodos , Animales , Bovinos , Femenino , Supervivencia de Injerto , Inmunohistoquímica , Insulina/análisis , Insulina/sangre , Trasplante de Islotes Pancreáticos/inmunología , Trasplante de Islotes Pancreáticos/fisiología , Radioinmunoensayo , Porcinos , Timo , Trasplante Heterólogo/inmunología , Trasplante Heterotópico/inmunologíaRESUMEN
Determinou-se a melhor relação vitamina E:vitamina C em dietas para frangos de corte, visando ao melhor desempenho produtivo e à melhor qualidade da carne das aves submetidas ao estresse pré-abate. Utilizaram-se 800 pintos de corte, machos, distribuídos em delineamento inteiramente ao acaso, em esquema fatorial 2x4, com dois níveis de suplementação de vitamina E - 0 e 250mg/kg - e quatro de vitamina C - 0, 150, 300 e 450mg/kg. Aos 42 dias de idade, 12 horas ante mortem, amostras de aves de cada tratamento foram submetidas ao estresse por calor e, em seguida, pelo transporte. Foram avaliadas características de desempenho - peso vivo, consumo de ração e conversão alimentar - , bem como rendimento de carcaça e qualidade da carne de peito e coxas - perda de água, cor e pH. Os níveis de vitaminas avaliadas não influenciaram nas características de desempenho avaliadas. Houve menor rendimento de peito (34,2 vs. 34,9%) e maior pH inicial (6,3 vs. 6,1) dos cortes, para aves que sofreram estresse em relação àquelas que não foram submetidas ao estresse pré-abate.
The best relationship for vitamin E:vitamin C in diets for broilers regarding growth performance and meat quality of birds submitted to pre-slaughter stress was determined. 800 male chicks at one day of age were distributed in a completely randomized design in a 2x4 factorial scheme, with two levels of vitamin E supplementation - 0 and 250mg/kg - and four of vitamin C - 0, 150, 300 and 450mg/kg. At 42 days of age, 12 hours ante-mortem, samples of birds from each treatment were submitted to heat stress and then transportation. The performance characteristics evaluated were body weight, feed intake and feed:gain ratio, carcass yield and meat quality of breast and thighs, water loss, color and pH. The levels of vitamins evaluated did not influence the performance characteristics measured. There was a lower breast yield (34.2 vs 34.9%) and higher initial pH (6.3 vs 6.1) in the cuts for birds that suffered stress than for those who did not undergo pre-slaughter stress.
Asunto(s)
Animales , Pollos/crecimiento & desarrollo , Pollos/fisiología , Vitamina E/administración & dosificación , Vitamina E/síntesis química , Antioxidantes , Carne/análisis , Trastornos de Estrés por Calor/veterinariaRESUMEN
Peripheral benzodiazepine receptors have been shown in some endocrine tissues, namely the testis, the adrenal gland, and the pituitary gland. In this work we evaluated whether peripheral benzodiazepine receptors can be found in the purified human pancreatic islets and whether they may have a role in insulin release. Binding of the isoquinoline compound [3H]1-(2-chlorophenyl-N-methyl-1-methyl-propyl)-3- isoquinolinecarboxamide (13H]PK-11195) a specific ligand of peripheral benzodiazepine receptors, to cellular membranes was saturable and Scatchard's analysis of the saturation curve demonstrated the presence of a single population of binding sites, with an affinity constant value of 9.20 +/- 0.80 nM and a maximum number of binding sites value of 8913 +/- 750 fmol/mg of proteins. PK-11195 and 7-chloro-1,3-dihydro-1-methyl-5-(p-chlorophenyl)-2H-1,4- benzodiazepine-2-on (Ro 5-4864) significantly potentiated insulin secretion from freshly isolated human islets at 3.3 mM glucose. These results show the presence of peripheral benzodiazepine receptors in purified human pancreatic islets and suggest their role in the mechanisms of insulin release.
Asunto(s)
Islotes Pancreáticos/metabolismo , Receptores de GABA-A/metabolismo , Benzodiazepinonas/farmacología , Humanos , Islotes Pancreáticos/efectos de los fármacos , Isoquinolinas/farmacologíaRESUMEN
This study evaluated the release of Th1 and Th2 cytokines from human lymphomononuclear cells (LMC) in response to purified human (HI) or bovine (BI) islets, and the role of long-term (3-4 weeks) islet culture and removal of monocyte-macrophage cells. The results showed that HI and BI caused a similar increase of the release of gamma interferon (IFN), IL-2 and IL-6 from LMC, whereas BI had a more marked effect than HI on IL-10 release. Culturing the islets had possible positive effects (reduction of IFN and IL-2), but also potentially negative effects (increase of TNF). Removal of monocyte-macrophage cells determined a significant reduction of IL-6, IL-10 and TNF production in response to xeno-islets.