RESUMO
A 59-year-old man with cervical spondylosis was scheduled for a posterior spine surgery. After induction of anaesthesia with propofol and fentanyl, and neuromuscular blockade with vecuronium, the trachea was intubated using an 8.0-mm ID refinforced tube, without difficulty. After inflation of the cuff with 6 ml of air, there was no gas leak around the tube. The patient was placed in the prone position, and the head fixed to the operating table, using head pins. Several minutes later, there was a marked gas leak around the tracheal tube cuff. Addition of air to the cuff did not solve the problem, indicating rupture of the cuff. A size 5 laryngeal mask airway was inserted while the tracheal tube was left in place with the patient in the prone position. Inflation of the cuff of the laryngeal mask with 15 ml of air and occluding the connector part of the laryngeal mask prevented the gas leak, and adequate ventilation volume could be maintained afterwards. We believe that insertion of the laryngeal mask airway may be useful in minimizing gas leakage around a tracheal tube.
Assuntos
Intubação Intratraqueal/instrumentação , Máscaras Laríngeas , Falha de Equipamento , Humanos , Masculino , Pessoa de Meia-IdadeRESUMO
Actin cytoskeletal reorganization and membrane trafficking are important for spine morphogenesis. Here we investigated whether the small GTPase, ADP-ribosylation factor 6 (ARF6), which regulates actin dynamics and peripheral vesicular trafficking, is involved in the regulation of spine formation. The developmental expression pattern of ARF6 in mouse hippocampus was similar to that of the post-synaptic density protein-95, and these molecules colocalized in mouse hippocampal neurons. Overexpression of a constitutively active ARF6 mutant in cultured hippocampal neurons decreased the spine density, whereas a dominant-negative ARF6 mutant increased the density. These results demonstrate a novel function for ARF6 as a key regulator of spine formation.
Assuntos
Fatores de Ribosilação do ADP/metabolismo , Espinhas Dendríticas/metabolismo , Regulação da Expressão Gênica no Desenvolvimento , Hipocampo/metabolismo , Proteínas Monoméricas de Ligação ao GTP/metabolismo , Neurônios/metabolismo , Fator 6 de Ribosilação do ADP , Fatores de Ribosilação do ADP/genética , Animais , Western Blotting , Células Cultivadas , Hipocampo/citologia , Hipocampo/embriologia , Camundongos , Microscopia de Fluorescência , Mutação , Neurônios/citologiaRESUMO
The membrane phospholipid phosphatidylinositol 4, 5-bisphosphate [PI(4,5)P(2)] is a critical signal transducer in eukaryotic cells. However, the physiological roles of the type I phosphatidylinositol phosphate kinases (PIPKIs) that synthesize PI(4,5)P(2) are largely unknown. Here, we show that the alpha isozyme of PIPKI (PIPKIalpha) negatively regulates mast cell functions and anaphylactic responses. In vitro, PIPKIalpha-deficient mast cells exhibited increased degranulation and cytokine production after Fcepsilon receptor-I cross-linking. In vivo, PIPKIalpha(-/-) mice displayed enhanced passive cutaneous and systemic anaphylaxis. Filamentous actin was diminished in PIPKIalpha(-/-) mast cells, and enhanced degranulation observed in the absence of PIPKIalpha was also seen in wild-type mast cells treated with latrunculin, a pharmacological inhibitor of actin polymerization. Moreover, the association of FcepsilonRI with lipid rafts and FcepsilonRI-mediated activation of signaling proteins was augmented in PIPKIalpha(-/-) mast cells. Thus, PIPKIalpha is a negative regulator of FcepsilonRI-mediated cellular responses and anaphylaxis, which functions by controlling the actin cytoskeleton and dynamics of FcepsilonRI signaling. Our results indicate that the different PIPKI isoforms might be functionally specialized.
Assuntos
Anafilaxia/metabolismo , Sinalização do Cálcio/fisiologia , Degranulação Celular/fisiologia , Mastócitos/fisiologia , Fosfotransferases (Aceptor do Grupo Álcool)/metabolismo , Actinas/metabolismo , Anafilaxia/genética , Animais , Sinalização do Cálcio/genética , Degranulação Celular/genética , Células Cultivadas , Isoenzimas/genética , Isoenzimas/metabolismo , Microdomínios da Membrana/metabolismo , Camundongos , Camundongos Knockout , Antígenos de Histocompatibilidade Menor , Fosfatidilinositol 4,5-Difosfato/metabolismo , Fosfotransferases (Aceptor do Grupo Álcool)/genética , Receptores de IgE/metabolismo , Tiazóis/farmacologiaRESUMO
The signaling pathway that triggers morphological differentiation of PC12 cells is mediated by extracellular signal-regulated kinase (ERK), the classic mitogen-activated protein (MAP) kinase. However, mediators of the pathway downstream of ERK have not been identified. We show here that phospholipase D2 (PLD2), which generates the pleiotropic signaling lipid phosphatidic acid (PA), links ERK activation to neurite outgrowth in nerve growth factor (NGF)-stimulated PC12 cells. Increased expression of wild type PLD2 (WT-PLD2) dramatically elongated neurites induced by NGF stimulation or transient expression of the active form of MAP kinase-ERK kinase (MEK-CA). The response was activity-dependent, because it was inhibited by pharmacological suppression of the PLD-mediated PA production and by expression of a lipase-deficient PLD2 mutant. Furthermore, PLD2 was activated by MEK-CA, whereas NGF-stimulated PLD2 activation and hypertrophic neurite extension were blocked by an MEK-specific inhibitor. Taken together, these results provide evidence that PLD2 functions as a downstream signaling effector of ERK in the NGF signaling pathway, which leads to neurite outgrowth by PC12 cells.
Assuntos
Proteínas Quinases Ativadas por Mitógeno/metabolismo , Fator de Crescimento Neural/farmacologia , Neuritos , Fosfolipase D/metabolismo , Actinas/metabolismo , Animais , Ativação Enzimática , Células PC12 , Ratos , Transdução de SinaisRESUMO
Stimulation of the neuronal cell adhesion molecule L1 in cerebellar granule neurons (CGNs) enhances neurite outgrowth and this response is inhibited by the primary alcohol ethanol. Because primary alcohols suppress the formation of the signaling lipid phosphatidic acid (PA) by phospholipase D (PLD), this observation prompted us to investigate whether PLD plays a role in the L1-mediated neurite outgrowth in CGNs. In the cerebellum of postnatal day 8 mice, PLD2 protein was abundantly expressed, while PLD1 expression was not detected. The L1-stimulated neurite outgrowth was inhibited by primary alcohols and by overexpression of lipase-deficient PLD2. Increases in cellular PA levels by direct PA application or overexpression of wild-type PLD2 mimicked the L1-dependent stimulation of neurite outgrowth. Furthermore, it was found that L1 stimulation in CGNs increased PLD activity concomitantly with phosphorylation of extracellular signal-regulated kinase (ERK), both of which were inhibited by the MAP kinase-ERK kinase (MEK) inhibitor. These results provide evidence that PLD2 functions as a downstream signaling molecule of ERK to mediate the L1-dependent neurite outgrowth of CGNs, a mechanism that may be related to alcohol-related neurodevelopmental disorders.
Assuntos
Sistema de Sinalização das MAP Quinases/fisiologia , Molécula L1 de Adesão de Célula Nervosa/fisiologia , Neuritos/fisiologia , Neurônios/efeitos dos fármacos , Neurônios/enzimologia , Fosfolipase D/fisiologia , Álcoois/farmacologia , Animais , Células Cultivadas , Cerebelo/citologia , Cerebelo/efeitos dos fármacos , Cerebelo/enzimologia , Inibidores Enzimáticos/farmacologia , Sistema de Sinalização das MAP Quinases/efeitos dos fármacos , Camundongos , Camundongos Endogâmicos ICR , Proteínas Quinases Ativadas por Mitógeno/efeitos dos fármacos , Proteínas Quinases Ativadas por Mitógeno/metabolismo , Molécula L1 de Adesão de Célula Nervosa/farmacologia , Neuritos/efeitos dos fármacos , Neurônios/citologia , Fosfolipase D/genética , Fosfolipase D/metabolismo , Fosforilação/efeitos dos fármacosAssuntos
Proteínas de Ligação ao GTP/metabolismo , Fosfotransferases (Aceptor do Grupo Álcool)/metabolismo , Fator 6 de Ribosilação do ADP , Fatores de Ribosilação do ADP/metabolismo , Animais , Ativação Enzimática , Humanos , Lisofosfolipídeos/metabolismo , Modelos Biológicos , Fosfatidilinositol 3-Quinases/metabolismo , Transdução de Sinais , Proteínas rac1 de Ligação ao GTP/metabolismo , Proteína rhoA de Ligação ao GTP/metabolismoRESUMO
Phosphatidylinositol 4-phosphate 5-kinase (PIP-5kin) regulates actin cytoskeletal reorganization through its product phosphatidylinositol 4,5-bisphosphate. In the present study we demonstrate that PIP-5kin is essential for neurite remodeling, which is regulated by actin cytoskeletal reorganization in neuroblastoma N1E-115 cells. Overexpression of wild-type mouse PIP-5kin-alpha inhibits the neurite formation that is normally stimulated by serum depletion, whereas a lipid kinase-defective mutant of PIP-5kin-alpha, D266A, triggers neurite extension even in the presence of serum and blocks lysophosphatidic acid-induced neurite retraction. These results phenocopy those previously reported for the small GTPase RhoA and its effector p160 Rho-associated coiled coil-forming protein kinase (ROCK). However, the ROCK-specific inhibitor Y-27632 failed to block the inhibition by PIP-5kin-alpha of neurite extension, whereas D266A did block the neurite retraction induced by overexpression of ROCK. These results, taken together, suggest that PIP-5kin-alpha functions as a downstream effector for RhoA/ROCK to couple lysophosphatidic acid signaling to neurite retraction presumably through its product phosphatidylinositol 4,5-bisphosphate.