RESUMO
The aim of this study was to evaluate the purine levels in serum and brains of mice experimentally infected by Cryptococcus neoformans. Twenty-four mice were divided into the following groups: a control group (n = 12; Group A) and an infection group with animals that were infected (n = 12; Group B) with a 0.3-mL intraperitoneal injection containing 1.7 × 107C. neoformans cells. Blood and brains were collected on days 20 (n = 6 per group) and 50 (n = 6 per group) post-infection (PI). Histopathology and lung and brain cultures were performed to confirm fungal infection and tissue injuries. The levels of adenosine triphosphate (ATP), adenosine diphosphate (ADP), adenosine monophosphate (AMP), adenosine (ADO), inosine (INO), hypoxanthine (HYPO), xanthine (XAN) and uric acid (UA) in brains and serum were measured by high-performance liquid chromatography (HPLC) analysis. At both time points, histopathology analysis revealed inflammatory infiltrates in the brains and lungs of infected mice; clinical signs, such as piloerection and clinical respiratory distress, were also observed. ATP levels were significantly increased on days 20 and 50 PI (P < 0.01) in brains and serum, while brain ADO levels were increased on day 20 PI; brain and serum ADO levels were decreased on day 50 PI. Levels of ADP and AMP did not differ between groups (P > 0.05). Serum levels of INO of infected mice increased only on day 50 PI (P < 0.05). HYPO levels were reduced in the brains of infected animals at both experimental time points and were decreased in serum at day 50 PI (P < 0.05). XAN levels increased in infected mice only in serum on day 50 PI (P < 0.05). The endogenous anti-oxidant uric acid was significantly increased in brain (days 20 and 50 PI) and decreased in serum. It is possible that C. neoformans infection in mice leads to a high ATP/ADO ratio that may improve the brain pro-inflammatory response during both periods, while high ATP levels in serum act as a systemic signal to improve the immune response. Moreover, the anti-oxidant uric acid may increase in the brain to protect inflamed tissue from oxidative stress.
Assuntos
Encéfalo/metabolismo , Criptococose/patologia , Cryptococcus neoformans/patogenicidade , Purinas/sangue , Purinas/farmacocinética , Animais , Criptococose/microbiologia , Masculino , CamundongosRESUMO
BACKGROUND: Sildenafil is used for the treatment of pediatric pulmonary hypertension. A dried blood spot (DBS)-based LC-MS method for sildenafil quantitation was developed and applied to a group of patients. RESULTS: DBS showed high portability and stability of samples, and the method was selective and linear for quantitation of sildenafil (5-3,000 ng/ml) and N-desmethyl-sildenafil (3-1,500 ng/ml). After a single oral dose of sildenafil (1 mg/kg), method evidenced poor metabolism in these patients. CONCLUSION: The method was successfully applied in peripheral blood and can be used for both pharmacokinetics and therapeutic drug monitoring. DBS proved to have advantages during sample translation and preservation of analytes. Data suggest that hazardous blood sildenafil levels may be reached in this population.
Assuntos
Cromatografia Líquida de Alta Pressão , Piperazinas/sangue , Sulfonamidas/sangue , Espectrometria de Massas em Tandem , Vasodilatadores/sangue , Criança , Pré-Escolar , Teste em Amostras de Sangue Seco , Monitoramento de Medicamentos , Feminino , Meia-Vida , Humanos , Hipertensão Pulmonar/tratamento farmacológico , Masculino , Piperazinas/farmacocinética , Piperazinas/uso terapêutico , Purinas/sangue , Purinas/farmacocinética , Purinas/uso terapêutico , Citrato de Sildenafila , Sulfonamidas/farmacocinética , Sulfonamidas/uso terapêutico , Vasodilatadores/farmacocinética , Vasodilatadores/uso terapêuticoRESUMO
OBJECTIVE: To evaluate the safety of intravenous (IV) sildenafil, an inhibitor of cyclic guanosine monophosphate-specific phosphodiesterase, in treating near-term and term newborns with persistent pulmonary hypertension of the newborn (PPHN). STUDY DESIGN: This was an open-label, dose-escalation trial in newborns with PPHN and an oxygenation index (OI) > 15. Sildenafil was delivered by continuous IV infusion for at least 48 hours and up to 7 days. RESULTS: Five centers enrolled a total of 36 neonates with PPHN at a mean of 34 +/- 17 hours of age; 29 of these neonates were already receiving inhaled nitric oxide (iNO). A significant improvement in OI (28.7 to 19.3; P = .0002) was observed after 4 hours of sildenafil infusion in the higher dose cohorts. Thirty-five neonates survived; 1 neonate required extracorporeal membrane oxygenation (ECMO) support. In 4 neonates, sildenafil was stopped due to adverse events. Seven neonates were enrolled before developing the need for iNO. In these neonates, OI improved significantly by 4 hours after initiation of sildenafil infusion (24.6 to 14.7; P = .009); 6 neonates completed treatment without the need for iNO or ECMO. CONCLUSIONS: IV sildenafil was well tolerated, and acute and sustained improvements in oxygenation were noted in those neonates who received the higher infusion doses.
Assuntos
Síndrome da Persistência do Padrão de Circulação Fetal/tratamento farmacológico , Inibidores de Fosfodiesterase/administração & dosagem , Piperazinas/administração & dosagem , Sulfonas/administração & dosagem , Estudos de Coortes , Relação Dose-Resposta a Droga , Feminino , Humanos , Lactente , Recém-Nascido , Infusões Intravenosas , Masculino , Síndrome da Persistência do Padrão de Circulação Fetal/metabolismo , Síndrome da Persistência do Padrão de Circulação Fetal/fisiopatologia , Inibidores de Fosfodiesterase/farmacocinética , Projetos Piloto , Piperazinas/farmacocinética , Troca Gasosa Pulmonar , Purinas/administração & dosagem , Purinas/farmacocinética , Citrato de Sildenafila , Sulfonas/farmacocinética , Resultado do TratamentoRESUMO
It has been long postulated that extracellular purines can modulate the function of the male reproductive system by interacting with different purinergic receptors of Sertoli and germinative cells. Many authors have described the biological changes induced by extracellular ATP and/or adenosine in these cells, and some hypothetical models for paracrine communication mediated by purines were proposed; however, the cellular source(s) of these molecules in seminiferous tubules remains unknown. In this study, we demonstrated for the first time that Sertoli cells are able to release ATP (0.3 nmol/mg protein) and adenosine (0.1 nmol/mg protein) in the extracellular medium, while germinative and myoid peritubular cells are able to secrete adenosine (0.02 and 0.37 nmol/mg protein, respectively). Indeed, all the three types of cells were able to release inosine at significant concentrations (about 0.4 nmol/mg protein). This differential secretion depending on the cellular type suggests that these molecules may be involved in the paracrine regulation and/or control of the maturation processes of these cells.
Assuntos
Adenina/análogos & derivados , Difosfato de Adenosina/análogos & derivados , Espaço Extracelular/metabolismo , Purinas/metabolismo , Túbulos Seminíferos/metabolismo , Células de Sertoli/metabolismo , Tioinosina/análogos & derivados , 5'-Nucleotidase/antagonistas & inibidores , Adenina/farmacologia , Adenosina/metabolismo , Difosfato de Adenosina/farmacologia , Trifosfato de Adenosina/metabolismo , Trifosfato de Adenosina/farmacocinética , Trifosfato de Adenosina/farmacologia , Marcadores de Afinidade/farmacologia , Animais , Células Cultivadas , Dipiridamol/farmacologia , Inibidores Enzimáticos/farmacologia , Espaço Extracelular/enzimologia , Células Germinativas/metabolismo , Cinética , Masculino , Comunicação Parácrina , Inibidores de Fosfodiesterase/farmacologia , Purinas/farmacocinética , Purinas/farmacologia , Ratos , Ratos Wistar , Receptores Purinérgicos/metabolismo , Túbulos Seminíferos/citologia , Células de Sertoli/efeitos dos fármacos , Tioinosina/farmacologiaRESUMO
1. The pattern of purine base uptake in culture epimastigotes of Trypanosoma cruzi can be predicted from cell growth rate and cell concentration, with the late log phase showing the greatest variability. 2. Uptake rates are unexpectedly low in the reproductive tissue amastigotes and high in the non-reproductive blood trypomastigotes. It is suggested that blood trypomastigotes metabolize and accumulate reserves of purine metabolites, whereas amastigotes depend on degradation of host cell RNA and nucleotides as purine sources. 3. All parasite forms salvage hypoxanthine and guanine in preference to adenine. Nifurtimox, dipyridamole and cytochalasin have no effect on uptake, whereas amphotericin B, allopurinol, xanthine and urate inhibit it. The alterations caused by urate are complex, apparently involving inhibition of the monooxypurine phosphoribosyltransferase and induction of permeation of purines into the cells.