T. Fukuse

Attenuation of ischaemia reperfusion injury by human thioredoxin.

BACKGROUND--Active oxygen species are thought to play a part in ischaemia reperfusion injury. The ability of a novel agent, human thioredoxin (hTRX), to attenuate lung damage has been examined in a rat model of ischaemia reperfusion injury. METHODS--Twenty eight animals were studied. At thoracotomy the left main bronchus and the left main pulmonary artery were clamped for 75 minutes and the lung was then reperfused for 20 minutes. Phosphate buffered saline was administered intravenously to nine control animals and hTRX (30 micrograms/g body weight) was given intravenously to another group of nine animals. Two experiments were carried out. The first (Exp 1) was a time matched pair experiment (five treated, five controls), and the second (Exp 2) was performed under controlled conditions (four treated, four controls; temperature 25 degrees C, humidity 65%). In another 10 nonischaemic rats and those in Exp 1 biochemical measurements of lipid peroxide, superoxide dismutase, and glutathione peroxide levels were performed. RESULTS--In both experiments rats perfused with hTRX survived longer than controls. In Exp 1 the arterial oxygen tension (PaO2) on air in the hTRX group was higher at 20 minutes than at one minute after reperfusion. In Exp 2 PaO2 at 20 minutes was higher in the hTRX group than in the controls. Lipid peroxide, superoxide dismutase, and glutathione peroxide levels in the control group were higher than in the hTRX group and in the non-ischaemic groups. Histological examination showed less thickening and oedema of the alveolar walls in the hTRX group than in controls. CONCLUSIONS--These results suggest that hTRX is effective as a radical scavenger and can limit the extent of ischaemia reperfusion injury of the lungs of experimental animals.

Mild hypothermia ameliorates lung ischemia reperfusion injury in an ex vivo rat lung model

Background: Ischemia reperfusion (I-R) injury of the lung frequently occurs after cardiopulmonary bypass, pulmonary thromboendarterectomy, lung transplantation, and major pulmonary resection with vascular reconstruction. Mild hypothermia ameliorates ischemia reperfusion injury of the brain and the liver. However, the effect of mild hypothermia on I-R injury of the lung has not been investigated. Methods: The lungs of Lewis rats underwent 80 min of ischemia followed by 60 min of reperfusion in an ex vivo perfusion model. The ambient temperature was maintained at either normothermia (38°C, n = 6) or mild hypothermia (35°C, n = 6) during the ischemia and reperfusion. Results: Pulmonary shunt fraction, peak inspiratory pressure, mean pulmonary arterial pressure during reperfusion, and the wet/dry weight ratio of the lung tissue at the end of reperfusion in the mild hypothermia group were significantly (p < 0.05) lower than those in the normothermia group. Total adenine nucleotide, adenosine triphosphate, adenosine diphosphate, and adenosine monophosphate after reperfusion in the mild hypothermia group were significantly (p < 0.05) higher than those in the normothermia group. Conclusion: Mild hypothermia attenuates I-R injury of the lung with maintained levels of intrapulmonary high-energy phosphate compounds after reperfusion, suggesting its beneficial effect on warm lung I-R in clinical settings.

Effects of cold preservation on the lung mechanical properties in rats

In lung transplantation, cold preservation is an important process. However, the mechanical changes in the airway and tissue during cold preservation, especially before reperfusion, are unknown. To test the hypothesis that the mechanical changes in the airway and lung parenchyma start during cold preservation, we investigated the mechanical properties of the rat lung as a whole organ and in excised lung strips. In the 0 h group, the lungs were not preserved. In the 9 and 24 h group, the lungs were preserved for 9 and 24 h at 4°C. After preservation, we evaluated the static compliance (Csta) of the whole lung as obtained from the pressure volume curves (n = 5 in each group). Also, we measured the input impedance taken by a computer-controlled small-animal ventilator (n = 9 in each group). All data were analyzed using a homogeneous linear model, which includes airway resistance (Raw), tissue elastance (H), and tissue resistance (G). Hysteresivity (η) was calculated as G/H. Moreover, the tissue elasticity (Eqs) obtained from the quasi-static stress-strain curves was compared. There was no significant difference in Csta among the three groups. Raw was significantly lower in the 24 h group than in the 0 h group (p < 0.01). Eqs was significantly higher in the preserved groups than in the 0 h group (p < 0.01). These results demonstrated that the changes in the three mechanical properties of the airway and the tissue started within 9 h of preservation.

Mitochondrial Injuries in Rat Lungs Preserved for 17 h: An Ultrastructural Study

Mitochondria of the small vasculature endothelial cells were examined in preserved rat lungs before and after reperfusion, and the ultrastructural changes were correlated with pulmonary function after reperfusion. Rat lungs were flushed with perfusate and prostaglandin E1 and divided into five groups (n = 5 in each group): group A, normal control group; group B, University of Wisconsin solution; group C, Euro-Collins solution; group D, ET-Kyoto solution, and group E, new ET-Kyoto solution. After preservation at 4°C for 17 h, the left lungs were reperfused at 37°C for 60 min. Tissue was sampled and mitochondria of the small vasculature endothelial cells were ultrastructurally analyzed by transmission electron microscopy before and after reperfusion. The ultrastructure of the mitochondria was well maintained in groups A, B and E before and after reperfusion. In group C, the number of severely degenerated mitochondria in the sectional area of 100 μm2 before reperfusion was 18.0 ± 3.9, which was significantly larger than in the other groups (p < 0.01), and the total number of mitochondria significantly decreased with reperfusion (from 24.8 ± 3.5 to 8.2 ± 2.4, p < 0.05). In group C, the shunt fraction, mean pulmonary arterial pressure and the wet-dry ratio of the lung tissue after reperfusion C were significantly higher than in the other groups (p < 0.05; 76.3 ± 1.5%, 54.8 ± 4.2 mm Hg, and 20.6 ± 2.5, respectively). A positive correlation was found between the percentage of the mitochondrial degeneration before reperfusion and the physiological parameters after reperfusion. Mitochondrial damage associated with cold ischemia is probably involved in lung injury caused by cold preservation and reperfusion.

Long-Term Remission after Brachytherapy with External Irradiation for Locally Advanced Lung Cancer

Three cases are reported who received brachytherapy with external irradiation for inoperable lung cancer and have shown long-term remission. The diseases were adenoid cystic carcinoma, recurrent adenocarcinoma and squamous cell carcinoma. The associated symptoms were severe cough and dyspnea in all 3 cases. They received 60 Gy of external irradiation. After an interval of 2 weeks, 6 Gy at a radius of 1 cm from the center of the source was delivered by iridium-192. They received 2–4 fractions at 1-week intervals. On termination of brachytherapy, complete response was observed in all cases. In 1 case, bronchial stenosis due to radiation-induced fibrosis was observed, but was successfully treated by bronchial stent. Cough and dyspnea disappeared, and all patients have been rendered asymptomatic for the last 2 years. Local disease was well controlled in 2 cases; however, minimal local recurrence was observed after a 2-year follow-up in 1 case.

Effects of Dibutyryl Cyclic Adenosine Monophosphate on the Ultrastructure of Endothelial Cells in Rat Lungs Cold Preserved for 15 Hours

Background: Dibutyryl cyclic adenosine monophosphate (db-cAMP) has been shown to protect vascular endothelial cells by increasing the level of intracellular cAMP, and we have previously reported its effectiveness in lung preservation. Here, the effects of db-cAMP in lung preservation were ultrastructurally investigated, and the ultrastructural changes before reperfusion were correlated with pulmonary function after reperfusion. Methods: The lungs of 17 Lewis rats were flushed with perfusate and prostaglandin E1, and were then divided into three groups. In the fresh group (n = 6), the lungs were flushed with extracellular-type trehalose-containing (ET-K) solution and were reperfused immediately. In the control group (n = 6) and db-cAMP group (n = 5), the lungs were flushed with ET-K solution and ET-K solution plus db-cAMP (2 mM), respectively, and were reperfused after cold preservation at 4°C for 15 h. Before reperfusion, tissue was sampled and ultrastructurally analyzed by transmission electron microscopy. Results: In the endothelial cells of pulmonary arterioles, the incidence of protrusion was significantly lower in the fresh and db-cAMP groups than in the control group (p < 0.05). The incidence of detachment and microvillus formation were significantly lower in the fresh and db-cAMP groups than in the control group (p < 0.01). The ultrastructure of the alveoli did not allow separation of the control and db-cAMP groups. The shunt fraction and wet to dry weight ratio of the lung tissue after reperfusion were significantly lower in the fresh and db-cAMP groups than in the control group (p < 0.01). Positive correlations were found between the incidence of these ultrastructural changes in the endothelial cells of the pulmonary arterioles and pulmonary function after reperfusion. Conclusion: These findings suggest that db-cAMP might attenuate the lung injury caused by cold preservation and ischemia-reperfusion, partly by suppressing the acceleration of the structural changes in the endothelial cells in the pulmonary arterioles.