RESUMO
The century-old inverted Keggin ion has been revisited in an effort to unleash its potential in the structural engineering and functional development of polyoxomolybdates (POMos). Over the past hundred years, attempts to program the metal-oxo scaffold of inverted Keggins have been conducted continually but without any success. In this work, a structurally inert, inverted Keggin-type POMo could finally be altered by means of a binary heterogroup-templated approach, resulting in the successful isolation of two lacunary species. The local structure and charge distribution of these species are adjustable, and hence they serve as available building blocks for the subsequent controlled assembly of a CeIII-incorporated derivative. From the plenary to the lacunary, the enclosed structure of the inverted Keggin has been opened up significantly, resulting in less steric hindrance, along with a transition from an electron neutral species to a negatively charged species. Owing to these beneficial properties, the emerging defect-containing polyanions demonstrated outstanding Lewis acid-base catalytic activity in the high efficiency production of pyrazoles.
RESUMO
In addition to improving the synthetic efficiency, the template method can do a lot more in the chemistry of polyoxopalladates (POPs), such as the establishment of novel metal-oxo scaffolds. In this endeavor, a binary system comprising heterogroups of nonmetallic {As/SiO4} and metallic {VO4/5} successfully fulfills the templated growth of two POPs with unprecedented seesaw- and spindle-like prototypes. Of these, self-aggregation of heterogroups beacons an effective route to break the highly symmetrical PdII-oxo matrix and to force the arrangement of addenda in a nonconventional manner. Aside from the interest in their structural features, the as-made POPs are available for immobilization on the mesoporous SBA-15 as precatalysts for ammonia synthesis. The outer cover of heterogroups in the POP precursors contributes to the ultrafine size and uniform distribution of derived Pd0 nanoparticles (PdNPs). With the help of plasma activation on H2 and N2, such PdNPs-SBA15 catalysts significantly improve the production performance of NH3, showcasing the maximum synthesis rate of 64.42 µmol/(min·gcat) with the corresponding energy yield as high as 4.38 g-NH3/kWh.
RESUMO
Accumulating evidence suggests a potential role of transient receptor potential vanilloid 1 (TRPV1) channels in inflammatory and cancer-related pain. However, the role of TRPV1 in the maintenance of neuropathic pain remains elusive. The current study investigated the effects of transient Trpv1 gene silencing using a small interference RNA (siRNA) on neuropathic pain induced by chronic constriction injury (CCI) of the sciatic nerve in rats. Seven days after CCI, the TRPV1 siRNA was intrathecally administered (5 µg/15 µl, once daily for 2 days). TRPV1 and Ca2+/calmodulin-dependent protein kinase II (CAMKII) expression and extracellular signal-regulated kinase (ERK) phosphorylation in the spinal cord were detected using western blotting. The thresholds to mechanical and thermal stimuli were determined before and after intrathecal TRPV1 siRNA administration. TRPV1 and CAMKII expression and ERK2 phosphorylation in the spinal cord were upregulated after CCI. Intrathecal administration of the TRPV1 siRNA not only attenuated behavioural hyperalgesia but also reduced the expression of TRPV1 and CAMKII, as well as ERK2 phosphorylation. Based on these results, silencing of the TRPV1 gene in the spinal cord attenuates the maintenance of neuropathic pain by inhibiting CAMKII/ERK2 activation and suggests that TRPV1 represents a potential target in pain therapy.
Assuntos
Proteína Quinase Tipo 2 Dependente de Cálcio-Calmodulina/metabolismo , Proteína Quinase 1 Ativada por Mitógeno/metabolismo , Neuralgia/patologia , Medula Espinal/metabolismo , Canais de Cátion TRPV/metabolismo , Animais , Proteína Quinase Tipo 2 Dependente de Cálcio-Calmodulina/antagonistas & inibidores , Constrição Patológica , Masculino , Neuralgia/metabolismo , Fosforilação , Interferência de RNA , RNA Interferente Pequeno/metabolismo , Ratos , Ratos Wistar , Canais de Cátion TRPV/antagonistas & inibidores , Canais de Cátion TRPV/genéticaRESUMO
α2-Adrenoceptor agonists attenuate hypersensitivity under neuropathic conditions. However, the mechanisms underlying this attenuation remain largely unknown. In the present study, we explored the potential roles of purinergic receptor 7 (P2X7R)/extracellular signal-regulated kinase (ERK) signaling in the anti-nociceptive effect of dexmedetomidine in a rat model of neuropathic pain induced by chronic constriction injury (CCI) of the sciatic nerve. An animal model of CCI was adopted to mimic the clinical neuropathic pain state. Behavioral hypersensitivity to mechanical and thermal stimuli was determined by von Frey filament and Hargreaves' tests, and the spinal P2X7R expression level and ERK phosphorylation were analyzed using western blot analysis and immunohistochemistry. In parallel with the development of mechanical and thermal hyperalgesia, a significant increase in P2X7R expression was noted in the ipsilateral spinal cord on day 7 after CCI. Intrathecal administration of dexmedetomidine (2.5 µg) for 3 days not only attenuated neuropathic pain but also inhibited the CCI-induced P2X7R upregulation and ERK phosphorylation. Intrathecal dexmedetomidine administration did not produce obvious effects on locomotor function. The present study demonstrated that dexmedetomidine attenuates the neuropathic pain induced by CCI of the sciatic nerve in rats by inhibiting spinal P2X7R expression and ERK phosphorylation, indicating the potential therapeutic implications of dexmedetomidine administration for the treatment of neuropathic pain.
RESUMO
STUDY OBJECTIVE: To examine the influence of epidural and intravenous (IV) lidocaine, and height of the epidural sensory block, on the dose of propofol required for induction of general anesthesia. DESIGN: Randomized controlled study. SETTING: University hospital. PATIENTS: 66 adult, ASA physical status 1 and 2 patients, aged 25 to 65 years, undergoing elective abdominal surgery. INTERVENTIONS: Patients were randomized to 4 groups: the epidural saline control group (Group C; L2-L3 puncture, epidural and IV saline), the IV lidocaine group (Group IV; L2-L3 puncture, saline epidural, IV lidocaine 1 mg/kg), the lumbar epidural lidocaine group (Group EL; L2-L3 puncture, 1.5% lidocaine epidural, IV saline), and the thoracic epidural lidocaine group (Group ET; T9-T10 puncture, 1.5%lidocaine epidural, IV saline). Two minutes after the beginning of the infusion of IV lidocaine or saline, propofol anesthesia was initiated. MEASUREMENTS: Mean arterial blood pressure (MAP), heart rate (HR), and sensory block height were monitored. The induction dose of propofol, its estimated effect-site concentration (Ce), and plasma concentration were measured at various time points. Finally, we recorded the time taken for the bispectral index (BIS) to decrease to 60, the plasma concentration of lidocaine at induction, and the occurrence of adverse events. The induction time (when BIS reached 60) also was recorded. MAIN RESULTS: The induction propofol dose, Ce, and plasma concentration of propofol when BIS equaled 60 were significantly lower in Group IV, Group EL, and Group ET than Group C. The above parameters in Group ET (T9 - T10 puncture) were significantly less than in Group EL (L2 - L3 puncture). The induction doses of propofol and plasma concentration of propofol and lidocaine were significantly higher in Group IV than in Groups EL or ET. CONCLUSIONS: Epidural and IV lidocaine reduce the dose of propofol required to induce general anesthesia. Administration of lidocaine via the epidural route reduces anesthetic requirements more so than the IV route. Propofol requirements were further reduced in patients with higher sensory epidural block.
Assuntos
Anestésicos Combinados/administração & dosagem , Anestésicos Intravenosos/administração & dosagem , Anestésicos Locais/administração & dosagem , Lidocaína/administração & dosagem , Propofol/administração & dosagem , Abdome/cirurgia , Adulto , Idoso , Anestesia Epidural/métodos , Anestesia Geral/métodos , Anestésicos Combinados/sangue , Anestésicos Intravenosos/sangue , Anestésicos Locais/sangue , Sedação Consciente/métodos , Relação Dose-Resposta a Droga , Eletroencefalografia/efeitos dos fármacos , Feminino , Frequência Cardíaca/efeitos dos fármacos , Humanos , Infusões Intravenosas , Lidocaína/sangue , Masculino , Pessoa de Meia-Idade , Propofol/sangue , Sensação/efeitos dos fármacosRESUMO
OBJECTIVES: This pilot study was designed to utilize stroke volume variation and cardiac index to ensure fluid optimization during one-lung ventilation in patients undergoing thoracoscopic lobectomies. METHODS: Eighty patients undergoing thoracoscopic lobectomy were randomized into either a goal-directed therapy group or a control group. In the goal-directed therapy group, the stroke volume variation was controlled at 10%±1%, and the cardiac index was controlled at a minimum of 2.5 L.min-1.m-2. In the control group, the MAP was maintained at between 65 mm Hg and 90 mm Hg, heart rate was maintained at between 60 BPM and 100 BPM, and urinary output was greater than 0.5 mL/kg-1/h-1. The hemodynamic variables, arterial blood gas analyses, total administered fluid volume and side effects were recorded. RESULTS: The PaO2/FiO2-ratio before the end of one-lung ventilation in the goal-directed therapy group was significantly higher than that of the control group, but there were no differences between the goal-directed therapy group and the control group for the PaO2/FiO2-ratio or other arterial blood gas analysis indices prior to anesthesia. The extubation time was significantly earlier in the goal-directed therapy group, but there was no difference in the length of hospital stay. Patients in the control group had greater urine volumes, and they were given greater colloid and overall fluid volumes. Nausea and vomiting were significantly reduced in the goal-directed therapy group. CONCLUSION: The results of this study demonstrated that an optimization protocol, based on stroke volume variation and cardiac index obtained with a FloTrac/Vigileo device, increased the PaO2/FiO2-ratio and reduced the overall fluid volume, intubation time and postoperative complications (nausea and vomiting) in thoracic surgery patients requiring one-lung ventilation.
Assuntos
Lobectomia Temporal Anterior/métodos , Hidratação/métodos , Ventilação Monopulmonar/métodos , Pneumonectomia/métodos , Volume Sistólico/fisiologia , Toracoscopia/métodos , Idoso , Pressão Arterial/fisiologia , Gasometria , Feminino , Frequência Cardíaca/fisiologia , Humanos , Masculino , Pessoa de Meia-Idade , Monitorização Fisiológica , Projetos Piloto , Reprodutibilidade dos Testes , Fatores de Tempo , Resultado do TratamentoRESUMO
OBJECTIVES: This pilot study was designed to utilize stroke volume variation and cardiac index to ensure fluid optimization during one-lung ventilation in patients undergoing thoracoscopic lobectomies. METHODS: Eighty patients undergoing thoracoscopic lobectomy were randomized into either a goal-directed therapy group or a control group. In the goal-directed therapy group, the stroke volume variation was controlled at 10%±1%, and the cardiac index was controlled at a minimum of 2.5 L.min-1.m-2. In the control group, the MAP was maintained at between 65 mm Hg and 90 mm Hg, heart rate was maintained at between 60 BPM and 100 BPM, and urinary output was greater than 0.5 mL/kg-1/h-1. The hemodynamic variables, arterial blood gas analyses, total administered fluid volume and side effects were recorded. RESULTS: The PaO2/FiO2-ratio before the end of one-lung ventilation in the goal-directed therapy group was significantly higher than that of the control group, but there were no differences between the goal-directed therapy group and the control group for the PaO2/FiO2-ratio or other arterial blood gas analysis indices prior to anesthesia. The extubation time was significantly earlier in the goal-directed therapy group, but there was no difference in the length of hospital stay. Patients in the control group had greater urine volumes, and they were given greater colloid and overall fluid volumes. Nausea and vomiting were significantly reduced in the goal-directed therapy group. CONCLUSION: The results of this study demonstrated that an optimization protocol, based on stroke volume variation and cardiac index obtained with a FloTrac/Vigileo device, increased the PaO2/FiO2-ratio and reduced the overall fluid volume, intubation time and postoperative complications (nausea and vomiting) in thoracic surgery patients requiring one-lung ventilation. .
Assuntos
Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Lobectomia Temporal Anterior/métodos , Hidratação/métodos , Ventilação Monopulmonar/métodos , Pneumonectomia/métodos , Volume Sistólico/fisiologia , Toracoscopia/métodos , Pressão Arterial/fisiologia , Gasometria , Frequência Cardíaca/fisiologia , Monitorização Fisiológica , Projetos Piloto , Reprodutibilidade dos Testes , Fatores de Tempo , Resultado do TratamentoRESUMO
BACKGROUND: Epidural lidocaine can be used when regional anesthesia needs to be established quickly, but the effect of co-administering epidural fentanyl on the minimum local analgesic concentration (MLAC) of lidocaine is not known. We compared the MLAC of epidural lidocaine in combination with different doses of fentanyl for epidural anesthesia in adults. METHODS: One hundred and twenty patients requiring epidural analgesia were randomly allocated to receive 20 ml of one of four solutions: lidocaine, or lidocaine plus fentanyl 1 µg/ml, 2 µg/ml, or 3 µg/ml. The first patient in each group was administered 1% lidocaine weight by volume; subsequent patients received a concentration determined by the response of the previous patient to a higher or lower concentration according to up and down sequential allocation in 0.1% increments. Efficacy was assessed using a visual analog pain scale, and accepted if this was = 10 mm on a 100 mm scale within 30 minutes. The extent of motor block and of nausea and vomiting were recorded at 30 minutes after administration of the epidural solution and two hours after surgery, respectively. RESULTS: The MLAC of lidocaine in those receiving lidocaine alone was 0.785% (95%CI 0.738 - 0.864). A significant dose-dependent reduction was observed with the addition of fentanyl: the MLAC of lidocaine with fentanyl at 2 µg/ml was 0.596% (95%CI 0.537 - 0.660) and 0.387% with fentanyl at 3 µg/ml (95%CI 0.329 - 0.446, P < 0.001). CONCLUSION: Epidural fentanyl significantly reduces the dose of lidocaine required for effective epidural analgesia in adults without causing adverse side effects.