RESUMO
Abstract Background Current evidence suggests that upregulation of polyamines system plays a role both in cognitive deficit and synaptic loss observed in Alzheimer's disease (AD). Objective The aim of this study was to determine the plasmatic concentration of polyamines in mild cognitive impairment (MCI) and AD patients in comparison with healthy controls (HC). Methods Plasmatic polyamines were quantified using the AbsoluteIDQ® p180 and liquid chromatography coupled to tandem mass spectrometry (LC/MS-MS). Results The study group comprised 34 AD patients, 20 MCI and 25 HC. All individuals were followed for 4 years. During this period 8 amnestic MCI patients (40% of the MCI sample at baseline) converted to AD. Spermidine level was lower in both patient groups (AD; MCI) compared to HC (p = 0.007). Plasma levels of spermine were higher in the MCI group (p < 0.001), but decreased in the sub-sample of MCI patients who converted to AD (p = 0.043). No statistically significant differences were found in ornithine and putrescine levels (p = 0.056 and p = 0.126, respectively). Discussion Our results suggest dynamic changes in the expression of polyamines in the MCI-AD continuum.
Assuntos
Humanos , Masculino , Feminino , Idoso , Idoso de 80 Anos ou mais , Poliaminas/sangue , Espermina/sangue , Doença de Alzheimer/fisiopatologia , Disfunção Cognitiva/fisiopatologia , Ornitina/sangue , Poliaminas/metabolismo , Biomarcadores/sangue , Putrescina/sangue , Espermidina/sangue , Cromatografia Líquida/métodos , Espectrometria de Massas em Tandem/métodos , Metabolômica/métodos , Doença de Alzheimer/diagnóstico , Disfunção Cognitiva/diagnósticoRESUMO
Diabetes mellitus (DM) is a worldwide disease characterized by metabolic disturbances, frequently associated with high risk of atherosclerosis and renal and nervous system damage. Here, we assessed whether metabolites reflecting oxidative redox state, arginine and nitric oxide metabolism, are differentially distributed between serum and red blood cells (RBC), and whether significant metabolism of arginine exists in RBC. In 90 patients with type 2 DM without regular treatment for diabetes and 90 healthy controls, paired by age and gender, we measured serum and RBC levels of malondialdehyde (MDA), nitrites, ornithine, citrulline, and urea. In isolated RBC, metabolism of L-[(14)C]-arginine was also determined. In both groups, nitrites were equally distributed in serum and RBC; citrulline predominated in serum, whereas urea, arginine, and ornithine were found mainly in RBC. DM patients showed hyperglycemia and increased blood HbA1C, and increased levels of these metabolites, except for arginine, significantly correlating with blood glucose levels. RBC were observed to be capable of catabolizing arginine to ornithine, citrulline and urea, which was increased in RBC from DM patients, and correlated with an increased affinity for arginine in the activities of putative RBC arginase (Kmâ=â0.23±0.06 vs. 0.50±0.13 mM, in controls) and nitric oxide synthase (Kmâ=â0.28±0.06 vs. 0.43±0.09 mM, in controls). In conclusion, our results suggest that DM alters metabolite distribution between serum and RBC, demonstrating that RBC regulate serum levels of metabolites which affect nitrogen metabolism, not only by transporting them but also by metabolizing amino acids such as arginine. Moreover, we confirmed that urea can be produced also by human RBC besides hepatocytes, being much more evident in RBC from patients with type 2 DM. These events are probably involved in the specific physiopathology of this disease, i.e., endothelial damage and dysfunction.
Assuntos
Arginina/metabolismo , Diabetes Mellitus Tipo 2/complicações , Diabetes Mellitus Tipo 2/metabolismo , Eritrócitos/metabolismo , Hiperglicemia/complicações , Hiperglicemia/metabolismo , Adulto , Idoso , Glicemia/metabolismo , Isótopos de Carbono , Estudos de Casos e Controles , Citrulina/sangue , Diabetes Mellitus Tipo 2/sangue , Diabetes Mellitus Tipo 2/patologia , Células Endoteliais/metabolismo , Feminino , Glicosilação , Hemoglobinas/metabolismo , Hemólise , Humanos , Hiperglicemia/sangue , Hiperglicemia/patologia , Masculino , Malondialdeído/sangue , Redes e Vias Metabólicas , Pessoa de Meia-Idade , Modelos Biológicos , Óxido Nítrico/metabolismo , Nitritos/sangue , Ornitina/sangue , Estresse Oxidativo , Ureia/sangueRESUMO
Ornithine, ammonia and homocitrulline are the major metabolites accumulating in hyperornithinemia-hyperammonemia-homocitrullinuria syndrome, a genetic disorder characterized by neurological regression whose pathogenesis is still not understood. The present work investigated the in vivo effects of intracerebroventricular administration of ornithine and homocitrulline in the presence or absence of hyperammonemia induced by intraperitoneal urease treatment on a large spectrum of oxidative stress parameters in cerebral cortex from young rats in order to better understand the role of these metabolites on brain damage. Ornithine increased thiobarbituric acid-reactive substances (TBA-RS) levels and carbonyl formation and decreased total antioxidant status (TAS) levels. We also observed that the combination of hyperammonemia with ornithine resulted in significant decreases of sulfhydryl levels, reduced glutathione (GSH) concentrations and the activities of catalase (CAT) and glutathione peroxidase (GPx), highlighting a synergistic effect of ornithine and ammonia. Furthermore, homocitrulline caused increases of TBA-RS values and carbonyl formation, as well as decreases of GSH concentrations and GPx activity. Hcit with hyperammonemia (urease treatment) decreased TAS and CAT activity. We also showed that urease treatment per se was able to enhance TBA-RS levels. Finally, nitric oxide production was not altered by Orn and Hcit alone or in combination with hyperammonemia. Our data indicate that the major metabolites accumulating in hyperornithinemia-hyperammonemia-homocitrullinuria syndrome provoke lipid and protein oxidative damage and a reduction of the antioxidant defenses in the brain. Therefore, it is presumed that oxidative stress may represent a relevant pathomechanism involved in the brain damage found in patients affected by this disease.
Assuntos
Erros Inatos do Metabolismo dos Aminoácidos/metabolismo , Amônia/metabolismo , Encéfalo/metabolismo , Citrulina/análogos & derivados , Homeostase/fisiologia , Ornitina/metabolismo , Erros Inatos do Metabolismo dos Aminoácidos/sangue , Erros Inatos do Metabolismo dos Aminoácidos/induzido quimicamente , Amônia/sangue , Animais , Antioxidantes/metabolismo , Catalase/metabolismo , Citrulina/metabolismo , Citrulina/urina , Glutationa Peroxidase/metabolismo , Injeções Intraperitoneais , Injeções Intraventriculares , Masculino , Óxido Nítrico/metabolismo , Ornitina/sangue , Ornitina/toxicidade , Oxirredução , Estresse Oxidativo/efeitos dos fármacos , Carbonilação Proteica/efeitos dos fármacos , Ratos , Ratos Wistar , Compostos de Sulfidrila/metabolismo , Substâncias Reativas com Ácido Tiobarbitúrico/metabolismo , UreaseRESUMO
PURPOSE: To investigate the effects of preventive enteral administration of ornithine alpha-ketoglutarate (OKG) in an ischemia-reperfusion rat model. METHODS: Sixty rats were randomized into five groups (G1-G5, n = 12). Each group was divided into two subgroups (n = 6) and treated with calcium carbonate (CaCa) or OKG by gavage. Thirty minutes later, the animals were anesthetized with xylazine 15mg + ketamine 1mg ip and subjected to laparotomy. G1-G3 rats served as controls. Rats in groups G4 and G5 were subjected to ischemia for 30 minutes. Ischemia was achieved by clamping the small intestine and its mesentery, delimiting a segment of bowel 5 cm long and 5 cm apart from the ileocecal valve. In addition, G5 rats underwent reperfusion for 30 minutes. Blood samples were collected at the end of the laparotomy (G1), after 30 minutes (G2, G4) and 60 minutes (G3, G5) to determine concentrations of metabolites (pyruvate, lactate), creatine phosphokinase (CPK), thiobarbituric acid reactive substances (TBARS) and glutathione (GSH). RESULTS: There was a significant decrease in tissue pyruvate and lactate and plasma CPK levels in OKG-treated rats at the end of reperfusion period. GSH levels did not change significantly in ischemia and reperfusion groups. However, TBARS levels increased significantly (p<0.05) in tissue samples in OKG-treated rats subjected to ischemia for 30 minutes. CONCLUSION: Short-term pretreatment with OKG before induction of I/R decreases tissue damage, increases pyruvate utilization for energy production in the Krebs cycle and does not attenuate the oxidative stress in this animal model.
Assuntos
Enteropatias/prevenção & controle , Intestino Delgado/irrigação sanguínea , Isquemia/complicações , Ornitina/análogos & derivados , Traumatismo por Reperfusão/prevenção & controle , Animais , Carbonato de Cálcio/sangue , Carbonato de Cálcio/uso terapêutico , Modelos Animais de Doenças , Intestino Delgado/efeitos dos fármacos , Isquemia/sangue , Ácido Láctico/sangue , Ligadura , Ornitina/sangue , Ornitina/uso terapêutico , Estresse Oxidativo/efeitos dos fármacos , Ácido Pirúvico/sangue , Distribuição Aleatória , Ratos , Traumatismo por Reperfusão/sangue , Fatores de Tempo , Resultado do TratamentoRESUMO
PURPOSE: To investigate the effects of preventive enteral administration of ornithine alpha-ketoglutarate (OKG) in an ischemia-reperfusion rat model. METHODS: Sixty rats were randomized into five groups (G1-G5, n = 12). Each group was divided into two subgroups (n = 6) and treated with calcium carbonate (CaCa) or OKG by gavage. Thirty minutes later, the animals were anesthetized with xylazine 15mg + ketamine 1mg ip and subjected to laparotomy. G1-G3 rats served as controls. Rats in groups G4 and G5 were subjected to ischemia for 30 minutes. Ischemia was achieved by clamping the small intestine and its mesentery, delimiting a segment of bowel 5 cm long and 5 cm apart from the ileocecal valve. In addition, G5 rats underwent reperfusion for 30 minutes. Blood samples were collected at the end of the laparotomy (G1), after 30 minutes (G2, G4) and 60 minutes (G3, G5) to determine concentrations of metabolites (pyruvate, lactate), creatine phosphokinase (CPK), thiobarbituric acid reactive substances (TBARS) and glutathione (GSH). RESULTS: There was a significant decrease in tissue pyruvate and lactate and plasma CPK levels in OKG-treated rats at the end of reperfusion period. GSH levels did not change significantly in ischemia and reperfusion groups. However, TBARS levels increased significantly (p<0.05) in tissue samples in OKG-treated rats subjected to ischemia for 30 minutes. CONCLUSION: Short-term pretreatment with OKG before induction of I/R decreases tissue damage, increases pyruvate utilization for energy production in the Krebs cycle and does not attenuate the oxidative stress in this animal model.
OBJETIVO: Investigar os efeitos da administração enteral preventiva de ornitina alfa-cetoglutarato (OKG) em modelo de isquemia-reperfusão no rato. MÉTODOS: Sessenta ratos foram randomizados em cinco grupos (G1-G5, n=12). Cada grupo foi redistribuído em dois subgrupos (n=6) e tratado com carbonato de cálcio (CaCa) ou OKG por gavagem. Trinta minutos mais tarde, os animais foram anestesiados com xilazina 1mg+cetamina 15mg i.p. e submetidos à laparotomia. Os ratos dos grupos G4-G5 foram submetidos à isquemia por 30 minutos. A isquemia foi obtida por pinçamento do intestino delgado, delimitando um segmento com 5 cm de comprimento e distando 5 cm da válvula ileocecal. O grupo G5 foi submetido à reperfusão por 30 minutos. Amostras de sangue foram coletadas no final da laparotomia (G1), após 30 minutos (G2, G4) e 60 minutos (G3, G5) para determinação das concentrações de metabolitos (piruvato, lactato), creatinofosfoquinase (CPK), substâncias reativas ao ácido tiobarbitúrico (TBARS) e glutationa (GSH). RESULTADOS: Observou-se redução significante (p<0,05) das concentrações de piruvato e lactato, teciduais e CPK plasmático em ratos tratados com OKG, no final do período de reperfusão. Não houve alteração significante nos níveis plasmáticos e teciduais de GSH. Entretanto os níveis de TBARS aumentaram significativamente (p<0,05) em amostras de tecido de ratos tratados com OKG submetido à isquemia por 30 minutos. CONCLUSÃO: o pré-tratamento em curto prazo com OKG antes da indução da I/R diminui a lesão tecidual, aumenta a utilização de piruvato para produção de energia no ciclo de Krebs, mas não atenua o estresse oxidativo neste modelo animal.
Assuntos
Animais , Ratos , Enteropatias/prevenção & controle , Intestino Delgado/irrigação sanguínea , Isquemia/complicações , Ornitina/análogos & derivados , Traumatismo por Reperfusão/prevenção & controle , Carbonato de Cálcio/sangue , Carbonato de Cálcio/uso terapêutico , Modelos Animais de Doenças , Intestino Delgado/efeitos dos fármacos , Isquemia/sangue , Ligadura , Ácido Láctico/sangue , Ornitina/sangue , Ornitina/uso terapêutico , Estresse Oxidativo/efeitos dos fármacos , Ácido Pirúvico/sangue , Distribuição Aleatória , Traumatismo por Reperfusão/sangue , Fatores de Tempo , Resultado do TratamentoRESUMO
1. Chronic renal failure (CRF) is associated with the abnormal regulation of nitric oxide (NO) synthesis at the systemic level. The transport of L-arginine, upregulated in blood cells from uraemic patients, modulates NO synthesis in this pathological condition. The model of partial nephrectomy in rats is widely accepted as a valid model of uraemia. Because there are no reports of L-arginine transport in blood cells from uraemic rats, the aim of the present study was to investigate L-arginine transport in red blood cells (RBCs) from these rats. 2. The kinetics of L-arginine transport in RBC and plasma and the amino acid profiles of RBC were investigated in control, sham-operated and subtotally nephrectomized rats. 3. L-Arginine transport was mediated via the cationic amino acid transport system y+ and a transport system with kinetics resembling the human system y+L. In control RBC, the apparent Ki for L-leucine inhibition of L-arginine transport via system y+L was 0.16 +/- 0.02 and 4.8 +/- 2 mmol/L in the presence of Li+ and Na+, respectively. 4. The Vmax values for L-arginine transport via system y+L and system y+ were similar in RBC from control sham-operated and uraemic rats. Moreover, L-arginine concentrations in plasma and RBC were not affected by uraemia. 5. The findings of the present study provide the first evidence that L-arginine transport in rat erythrocytes is mediated by two distinct cationic transport systems with characteristics of systems y+ and y+L, which accept neutral amino acids only in the presence of Li+. In contrast with previous studies in uraemic patients, plasma levels and maximal transport rates of L-arginine were not altered in this rat model of CRF.
Assuntos
Sistema y+L de Transporte de Aminoácidos/metabolismo , Sistema y+ de Transporte de Aminoácidos/metabolismo , Arginina/metabolismo , Eritrócitos/metabolismo , Uremia/metabolismo , Sistema y+ de Transporte de Aminoácidos/antagonistas & inibidores , Sistema y+L de Transporte de Aminoácidos/antagonistas & inibidores , Animais , Arginina/sangue , Arginina/farmacologia , Citrulina/sangue , Modelos Animais de Doenças , Eritrócitos/efeitos dos fármacos , Cinética , Leucina/sangue , Leucina/farmacologia , Lisina/sangue , Lisina/farmacologia , Masculino , Nefrectomia , Ornitina/sangue , Ratos , Ratos Wistar , Uremia/sangueRESUMO
OBJECTIVE: We compared the effects of an arginine-supplemented diet with those of an isocaloric isonitrogenous diet on immune and metabolic response of children with burns. METHODS: This was a double-blind, randomized, placebo-controlled trial in a burn treatment center of a pediatric hospital in Santiago, Chile. All children (1-5 y of age) admitted within 48 h of a moderate to deep burn injury covering 10% to 40% of total body surface area were evaluated. Twenty-eight children met the criteria and were randomly assigned to receive an arginine-supplemented diet (AG; n = 14) or an isocaloric isonitrogenous diet (CG; control, n = 14) for 14 d. Samples were collected at admission (baseline) and on days 7 and 14 for lymphoproliferative response to mitogens, plasma interleukins (interleukin-1, interleukin-6, tumor necrosis factor-alpha), plasma arginine and ornithine levels, serum C-reactive protein, prealbumin, albumin, glucose, and total urinary nitrogen. RESULTS: The AG enhanced lymphoproliferative responses (analysis of variance, P < 0.05), which were 72% of normal at baseline in both groups; by day 7 responses increased to 144% in the AG group and decreased to 56% in the CG group; both groups returned to normal by day 14. Baseline interleukin-6 was significantly increased in all children. There were no differences in plasma concentrations of interleukin-1, interleukin-6, tumor necrosis factor-alpha, C-reactive protein, prealbumin, albumin, or glucose between the AG and CG groups. On day 7 plasma ornithine levels increased significantly in the AG versus CG group (P < 0.05); arginine levels showed no change. CONCLUSIONS: An exclusively AG improves mitogen-stimulated lymphocyte proliferation in burned children. The benefits of arginine for the immune system do not appear to be related to a metabolic response. The biological significance of this finding remains to be determined.
Assuntos
Arginina/administração & dosagem , Queimaduras/imunologia , Queimaduras/metabolismo , Nutrição Enteral/métodos , Aminoácidos/sangue , Glicemia/análise , Queimaduras/dietoterapia , Proteína C-Reativa/análise , Pré-Escolar , Método Duplo-Cego , Humanos , Lactente , Interleucina-6/sangue , Ativação Linfocitária , Ornitina/sangue , Placebos , Pré-Albumina/análise , Albumina Sérica/análise , Fator de Necrose Tumoral alfa/sangueRESUMO
1. Treatment with haemodialysis and continuous ambulatory peritoneal dialysis (CAPD) presents different pathophysiological profiles and it has been suggested that clinical outcome in chronic renal failure may depend on the mode of dialysis. The transport of L-arginine, a precursor of nitric oxide, into blood cells is increased in uraemic patients on haemodialysis. The present study was designed to investigate L-arginine transport into red blood cells (RBC) in uraemic patients not yet on dialysis and on CAPD therapy. 2. Eleven uraemic patients not yet on dialysis and 17 on CAPD were included in the study. L-Arginine transport into RBC and plasma and RBC amino acid profiles were analysed in these sets of patients. 3. L-Arginine transport via system y(+), but not y(+)L, into RBC, was significantly increased in undialysed uraemic patients (459 +/- 40 micromol/L per cell per h) and CAPD patients (539 +/- 61 micromol/L per cell per h) compared with controls (251 +/- 39 micromol/L per cell per h). High-pressure liquid chromatography measurements demonstrated low levels of plasma L-arginine in uraemic patients both on CAPD (54 +/- 3 micromol/L) and not yet on dialysis (80 +/- 6 micromol/L) compared with control subjects (146 +/- 14 micromol/L). 4. Our findings provide the first evidence that uraemic patients not yet on dialysis and on CAPD present with an activation of L-arginine transport via system y(+) into RBC associated with reduced plasma levels of L-arginine.
Assuntos
Arginina/farmacocinética , Falência Renal Crônica/sangue , Diálise Peritoneal Ambulatorial Contínua , Arginina/sangue , Transporte Biológico , Citrulina/sangue , Eritrócitos/metabolismo , Feminino , Humanos , Falência Renal Crônica/fisiopatologia , Lisina/sangue , Masculino , Pessoa de Meia-Idade , Ornitina/sangue , Uremia/sangue , Uremia/fisiopatologiaRESUMO
PURPOSE: To analyze the importance f optical coherence tomography (OCT) to diagnose the cystoid macular edema in a case of gyrate atrophy. DESIGN: Observational case report. METHODS: A 12-year-old boy presenting with gyrate atrophy of the choroid and retina underwent ophthalmologic, clinical, and laboratory tests. RESULTS: Plasma ornithine level was 735 mumol/l. Fluorescein angiography showed bilateral hyperfluorescence involving the central region of the macula. Optical coherence tomography (OCT) disclosed bilateral intraretinal cysts areas of low reflectivity with occasional high-signal elements bridging the retinal layers and intraretinal thickening. CONCLUSIONS: Both fluorescein angiography and OCT were helpful to confirm the diagnosis of macular involvement as a complication of gyrate atrophy of the choroid and retina in a patient who presented without any clinical evidence of cystoid macular edema, except a decrease in visual acuity.
Assuntos
Corioide/patologia , Atrofia Girata/complicações , Edema Macular/diagnóstico , Edema Macular/etiologia , Retina/patologia , Criança , Angiofluoresceinografia/métodos , Atrofia Girata/diagnóstico , Humanos , Masculino , Ornitina/sangue , Tomografia de Coerência Óptica/métodosRESUMO
OBJECTIVE: To test the hypothesis that cardiopulmonary bypass used for repair of ventricular septal defects and atrioventricular septal defects would decrease availability of urea cycle intermediates including arginine and subsequent nitric oxide availability. STUDY DESIGN: Consecutive infants (n = 26) undergoing cardiopulmonary bypass for repair of an unrestrictive ventricular septal defect or atrioventricular septal defect were studied. Blood samples were collected immediately before surgery, immediately after surgery, and 12 hours, 24 hours, and 48 hours after surgery. Urea cycle intermediates, including citrulline, arginine, and ornithine, were measured by amino acid analysis. Nitric oxide metabolites were measured by means of the modified Griess reaction. RESULTS: Cardiopulmonary bypass caused a significant decrease in the urea cycle intermediates arginine, citrulline, and ornithine at all postoperative time points compared with preoperative levels. The ratio of ornithine to citrulline, a marker of urea cycle function, was elevated at all postoperative time points compared with preoperative values, indicating decreased urea cycle function. Nitric oxide metabolites were significantly decreased at all postoperative time points except for 48 hours, compared with preoperative levels. CONCLUSIONS: Cardiopulmonary bypass significantly decreases availability of arginine, citrulline, and nitric oxide metabolites in the postoperative period. Decreased availability of nitric oxide precursors may contribute to the increased risk of postoperative pulmonary hypertension.