Neutrophil elastase inhibitor (sivelestat) attenuates subsequent ventilator-induced lung injury in mice.

Mechanical ventilation can paradoxically cause acute lung injury, which is termed ventilator-induced lung injury. Neutrophil recruitment and neutrophil elastase release play a central role in the pathogenesis of ventilator-induced lung injury including cell damage, extracellular matrix degradation and alveolar-capillary hyperpermeability. We therefore speculated that neutrophil elastase inhibition ameliorates ventilator-induced lung injury. Anesthetized C57/BL6 mice received mechanical ventilation with a high tidal volume (V(T); 20 ml/kg) for 4 h. The neutrophil elastase inhibitor (sivelestat, 100 mg/kg) or saline was given intraperitoneally (i.p.) 30 min before ventilation. Sivelestat completely inhibited both neutrophil elastase and myeloperoxidase activities that were increased by ventilation, and attenuated the histopathological degree of lung damage, neutrophil accumulation and lung water content, as well as the concentration of macrophage inflammatory protein (MIP)-2, interleukin (IL)-6 and tumor necrosis factor (TNF)-alpha in bronchoalveolar lavage fluid and serum. Moreover, mechanical ventilation increased the phosphorylation of c-Jun NH2-terminal kinase (JNK) and the expression of early growth response gene-1 (Egr-1) mRNA, and these increases were also recovered by sivelestat. The terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end-labeling (TUNEL) staining revealed apoptotic cells mainly in alveolar epithelial cells and their numbers corresponded to histological damage. These data suggested that sivelestat could protect against ventilator-induced lung injury by suppressing apoptotic responses through mechanical stress-induced cell signaling in addition to inhibiting neutrophil chemotaxis.

Usefulness of the oximetry test for the diagnosis of sleep apnea syndrome in Japan.

We evaluated the usefulness of oximetry tests that are frequently used as screening tools for sleep apnea syndrome (SAS) by determining the level of agreement between oximetry test results and polysomnography test (PSG) results. We retrospectively examined 135 patients suspected of having SAS. Although the oximetry desaturation index (DSI) seemed better than the oximetry apnea index in the agreement with the polysomnography respiratory disturbance index (RDI), the criteria of DSI greater than or equal to 15 was not sensitive enough to screen for moderate SAS (PSG-RDI >or= 20). Multivariate analyses revealing that body mass index (BMI) as well as DSI correlated well with PSG-RDI, we established a new criterion by adding the BMI score (DSI >or= 15 or BMI >or= 25), which remarkably improved the sensitivity. This criterion may be useful not only in clinical practice but also in medical checkups for asymptomatic patients, and also suggests that obese patients with sleep disturbance should undergo PSGs, irrespective of the DSI score.

Ventilator-induced lung injury is reduced in transgenic mice that overexpress endothelial nitric oxide synthase.

Although mechanical ventilation (MV) is an important supportive strategy for patients with acute respiratory distress syndrome, MV itself can cause a type of acute lung damage termed ventilator-induced lung injury (VILI). Because nitric oxide (NO) has been reported to play roles in the pathogenesis of acute lung injury, the present study explores the effects on VILI of NO derived from chronically overexpressed endothelial nitric oxide synthase (eNOS). Anesthetized eNOS-transgenic (Tg) and wild-type (WT) C57BL/6 mice were ventilated at high or low tidal volume (Vt; 20 or 7 ml/kg, respectively) for 4 h. After MV, lung damage, including neutrophil infiltration, water leakage, and cytokine concentration in bronchoalveolar lavage fluid (BALF) and plasma, was evaluated. Some mice were given N(omega)-nitro-L-arginine methyl ester (L-NAME), a potent NOS inhibitor, via drinking water (1 mg/ml) for 1 wk before MV. Histological analysis revealed that high Vt ventilation caused severe VILI, whereas low Vt ventilation caused minimal VILI. Under high Vt conditions, neutrophil infiltration and lung water content were significantly attenuated in eNOS-Tg mice compared with WT animals. The concentrations of macrophage inflammatory protein-2 in BALF and plasma, as well as plasma tumor necrosis factor-alpha and monocyte chemoattractant protein-1, also were decreased in eNOS-Tg mice. L-NAME abrogated the beneficial effect of eNOS overexpression. In conclusion, chronic eNOS overexpression may protect the lung from VILI by inhibiting the production of inflammatory chemokines and cytokines that are associated with neutrophil infiltration into the air space.

[A case of pneumocystis carinii pneumonia associated with low dose methotrexate treatment for rheumatoid arthritis and trimethoprim-sulphamethoxazole induced pancytopenia].

A 64-year-old man was admitted to our hospital complaining of dyspnea and fever. He had been treated with low-dose methotrexate for rheumatoid arthritis. Chest radiography showed diffuse ground-glass attenuation in both lung fields, and hypoxia was detected. Pneumosystis carinii pneumonia was demonstrated on transbronchial lung biopsy, and the serum beta-D glucan level was high. We started treatment with trimethoprim-sulphamethoxazole, but respiratory failure worsened, and drug-induced pancytopenia occurred. Although trimethoprim-sulphamethoxazole was stopped, pancytopenia persisted and the patient required ventilatory support. After we changed the medication from trimethoprim-sulphamethoxazole to pentamidine, respiratory failure improved. It was thought that pneumocystis carinii pneumonia was associated with low-dose methotrexate and that trimethoprim-sulphamethoxazole interacted with methotrexate to induce severe pancytopenia.

[Pulmonary thromboembolism associated with familial protein C deficiency type I].

A 66-year-old man was admitted to our hospital because of progressive dyspnea on effort. Arterial blood gas analysis showed severe hypoxemia, and a chest radiograph revealed reticular shadows in both lower lungs and an increase of the cardiothoracic ratio. Echocardiography demonstrated mild indentation of the interventricular septum toward the left ventricle, moderate pericardial effusion and pulmonary hypertension. From these data, we diagnosed pulmonary thromboembolism and started anticoagulation therapy. After the addition of the administration of warfarin and oxygen therapy, his symptoms disappeared. However, we could not obtain more supporting evidence of thromboembolization by methods of ventilation-perfusion scanning, digital subtraction angiography of the pulmonary artery, or venography. Blood coagulation analysis demonstrated that the patient's plasma protein C antigen levels and its activity were depleted. The patient's son had a history of thrombophlebitis and pulmonary embolization, and his data of protein C antigen levels was also decreased. Therefore, this patient was found to have a character of familial protein C deficiency type I. We could not get the conclusive proof of pulmonary thromboembolism, but we considered that the presence of familial protein C deficiency may cause exacerbation of pulmonary hypertension.