Objective: To evaluate the effects that administering dexamethasone before the induction of ventilator-induced lung injury (VILI) has on the temporal evolution of that injury. Methods: Wistar rats were allocated to one of three groups: pre-VILI administration of dexamethasone (dexamethasone group); pre-VILI administration of saline (control group); or ventilation only (sham group). The VILI was induced by ventilation at a high tidal volume. Animals in the dexamethasone and control groups were euthanized at 0, 4, 24, and 168 h after VILI induction. We analyzed arterial blood gases, lung edema, cell counts (total and differential) in the BAL fluid, and lung histology. Results: At 0, 4, and 24 h after VILI induction, acute lung injury (ALI) scores were higher in the control group than in the sham group (p < 0.05). Administration of dexamethasone prior to VILI induction decreased the severity of the lung injury. At 4 h and 24 h after induction, the ALI score in the dexamethasone group was not significantly different from that observed for the sham group and was lower than that observed for the control group (p < 0.05). Neutrophil counts in BAL fluid were increased in the control and dexamethasone groups, peaking at 4 h after VILI induction (p < 0.05). However, the neutrophil counts were lower in the dexamethasone group than in the control group at 4 h and 24 h after induction (p < 0.05). Pre-treatment with dexamethasone also prevented the post-induction oxygenation impairment seen in the control group. Conclusions: Administration of dexamethasone prior to VILI induction attenuates the effects of the injury in Wistar rats. The molecular mechanisms of such injury and the possible clinical role of corticosteroids in VILI have yet to be elucidated.

Keywords: Ventilator-induced lung injury; Dexamethasone; Respiratory distress syndrome, adult.

Objective: To determine whether tramadol has a protective effect against lung injury induced by skeletal muscle ischemia-reperfusion. Methods: Twenty Wistar male rats were allocated to one of two groups: ischemia-reperfusion (IR) and ischemia-reperfusion + tramadol (IR+T). The animals were anesthetized with intramuscular injections of ketamine and xylazine (50 mg/kg and 10 mg/kg, respectively). All of the animals underwent 2-h ischemia by occlusion of the femoral artery and 24-h reperfusion. Prior to the occlusion of the femoral artery, 250 IU heparin were administered via the jugular vein in order to prevent clotting. The rats in the IR+T group were treated with tramadol (20 mg/kg i.v.) immediately before reperfusion. After the reperfusion period, the animals were euthanized with pentobarbital (300 mg/kg i.p.), the lungs were carefully removed, and specimens were properly prepared for histopathological and biochemical studies. Results: Myeloperoxidase activity and nitric oxide levels were significantly higher in the IR group than in the IR+T group (p = 0.001 for both). Histological abnormalities, such as intra-alveolar edema, intra-alveolar hemorrhage, and neutrophil infiltration, were significantly more common in the IR group than in the IR+T group. Conclusions: On the basis of our histological and biochemical findings, we conclude that tramadol prevents lung tissue injury after skeletal muscle ischemia-reperfusion.

Keywords: Tramadol; Muscle, skeletal; Ischemic attack, transient; Lung Injury.

The ischemia-reperfusion injury is a common pathophysiologic phenomenon in many diseases seen in daily clinical practice. The lung can be affected both directly, as in pulmonary edema after lung transplant or after resolution of pulmonary thromboembolism, and indirectly, as in shock states or after reperfusion injury in distant organs as intestine or lower extremities. The latter situation can occur secondary to aortic occlusion for surgical procedures. Many mediators have been implicated in the ischemia-reperfusion injury: oxygen free radicals, lipid products as thromboxane, adhesion molecules involved in leukocyte-endothelial interaction, tumor necrosis factor, among others. Therapeutic strategies for the reperfusion injury are used only at the experimental level and in very few clinical studies. Antioxidants, inhibitors of lipid mediators and of the leukocyte-endothelial interaction and promoters of blood flow in post-ischemic vessels have been used.

Keywords: Lung. Injury. Reperfusion. Ischemia.

Transfusion-related acute lung injury (TRALI) is a serious clinical syndrome associated with the transfusion of plasma-containing blood components. Recently, TRALI has come to be recognized as the leading cause of transfusion-related death in the United States and United Kingdom. This complication typically presents as shortness of breath, hypoxemia, hypotension, fever and noncardiogeneic pulmonary edema, all occurring during or within 6 h after transfusion. Although the mechanism of TRALI has not been fully elucidated, it has been associated with human leukocyte antigen antibodies (class I, class II or neutrophil alloantigens) and with biologically active mediators in stored cellular blood components. Most of the donors implicated in cases of TRALI are multiparous women. Rarely diagnosed, TRALI can be confused with other causes of acute respiratory failure. Greater knowledge regarding TRALI on the part of clinicians could be crucial in preventing and treating this severe complication of blood transfusion.

Keywords: Blood transfusion; Respiratory insufficiency; HLA antigens.

Introduction: Surgical procedures requiring aortic occlusion have been associated with pulmonary reperfusion injury. The authors studied the pulmonary edema in a reperfusion injury model by aortic occlusion in rats. Material and methods: Thirty-three Wistar rats were anesthetized with intraperitoneal injection of sodium pentobarbital (20 mg/kg). Using a midline abdominal incision, the infra-renal aorta was isolated and the animals were randomized into three groups. Ischemia-reperfusion group (IRG, n = 5): rats that underwent 30 min of aorta occlusion and were followed during 120 min of reperfusion. Ischemia group (IG, n = 5): rats that underwent 30 min of aorta occlusion. Control group (CG, n = 5): rats that underwent sham operations without aorta occlusion and were followed during 150 min. Histopathologic examination of the right lung was performed. The pulmonary edema was studied by morphometric analysis and so was the leukocytes infiltration. Eighteen rats (6 rats in each group) were studied with respect to lung fresh/dry weight ratio. ANOVA was used to analyze the morphometric results and the lung fresh/dry weight ratio, with Bonferroni adjustment for paired multiple comparisons. Animals of the IRG presented more pulmonary edema than those of the IG and CG (0.24 vs. 0.17 and 0.17, p < 0.001). There was no difference between the groups regarding the lung fresh/dry weight ratio. There were more inflammatory cells in the lungs of the rats submitted to ischemia-reperfusion. The authors concluded that infra-renal abdominal aorta cross-clamping and unclamping are associated with pulmonary edema. This edema is not induced by elevation of the hydrostatic pressure due to the aortic occlusion, since it was not seen in animals that were only submitted to ischemia.

Keywords: ischemia, reperfusion, pulmonary edema, inbred strains rats

Diabetes mellitus is an endocrine/metabolic disorder characterized by hyperglycemia. Its impact on the respiratory system is characterized by functional changes and alterations in gas exchange. The objective of this study was to evaluate the increase in oxidative stress and the potential damages to the lung structure in an experimental model of streptozotocin-induced diabetes. We conducted histological, biochemical and blood gas analyses in the lungs of diabetic rats. We concluded that the effects of experimental diabetes mellitus include oxidative stress, structural changes in the lung tissue and altered gas exchange.

Keywords: Lung; Diabetes mellitus; Oxidative stress; Diabetes mellitus, experimental; Free radicals.

Since they were first established, ex vivo models of lung reconditioning have been evaluated extensively. When rejected donor lungs are used, the great variability among the cases can hinder the progress of such studies. In order to avoid this problem, we developed a technique that consists of separating the lung block into right and left blocks and subsequently reconnecting those two blocks. This technique allows us to have one study lung and one control lung.

Keywords: Lung transplantation; Transplantation conditioning; Organ preservation; Organ preservation solutions.

Although mechanical ventilation is an important therapy, it can result in complications. One major complication is ventilator-induced lung injury, which is caused by alveolar hyperdistension, leading to an inflammatory process, with neutrophilic infiltration, hyaline membrane formation, fibrogenesis and impaired gas exchange. In this process, cellular mechanotransduction of the overstretching stimulus is mediated by means of the cytoskeleton and its cell-cell and cell-extracellular matrix interactions, in such a way that the mechanical stimulus of ventilation is translated into an intracellular biochemical signal, inducing endothelial activation, pulmonary vascular permeability, leukocyte chemotaxis, cytokine production and, possibly, distal organ failure. Clinical studies have shown the relationship between pulmonary distension and mortality in patients with ventilator-induced lung injury. However, although the cytoskeleton plays a fundamental role in the pathogenesis of ventilator-induced lung injury, there have been few in vivo studies of alterations in the cytoskeleton and in cytoskeleton-associated proteins during this pathological process.

Keywords: Respiration, artificial; Cytoskeleton; Cell adhesion molecules; Focal adhesions; Mechanotransduction, cellular

Objective: To investigate the effects of quercetin in a model of bleomycin-induced pulmonary inflammation and fibrosis. Methods: Seventynine adult male hamsters were randomized to receive intratracheal (IT) instillations and intraperitoneal (IP) injections in four configurations: IP vehicle/IT saline (VS group, n = 16); IP quercetin/IT saline (QS group, n = 16); IP vehicle/IT bleomycin (VB group, n = 27); and IP quercetin/ IT bleomycin (QB group, n = 20). Quercetin and bleomycin were administered at 30 mg/kg/day and 10 U/kg, respectively. Quercetin was started/discontinued 3 days before/14 days after the IT instillations. Results: The mortality rate was significantly higher in the VB group than in the other groups (44% vs. VS: 0%; QS: 0%; and QB: 15%). Lung levels of thiobarbituric acid reactive substances (× 10−2 nmol/mg) were significantly higher in the VB group (6.6 ± 1.3 vs. VS: 5.5 ± 0.8; QS: 2.5 ± 0.6; and QB: 5.8 ± 0.6). Lung levels of reduced glutathione (× 10−2 nmol/mg) were significantly lower in the VB/QB groups than in the VS/QS groups (28.9 ± 13.8/28.6 ± 14.8 vs. 43.9 ± 16.0/51.1 ± 20.3), whereas those of hydroxyproline (mg/g) were significantly higher (201.6 ± 37.3/177.6 ± 20.3 vs. 109.6 ± 26.1/117.5 ± 32.0).Mean lung septal thickness (μm) was greatest in the VB group (16.9 ± 3.2 vs. VS: 3.0 ± 0.3; QS: 3.3 ± 0.2; and QB: 5.2 ± 1.1). Conclusions: In a hamster model of lung injury, quercetin exhibited anti-inflammatory effects that are related, at least in part, to its antioxidant properties.

Keywords: Pulmonary fibrosis; Bleomycin; Flavonoids; Lipid peroxidation.

Objective: To evaluate the effects of immunization with a DNA-hsp65 vaccine in an experimental model of pulmonary fibrosis. Methods: A total of 120 male C57BL/6 mice were distributed into four groups: SS, injected with saline (placebo) and then receiving intratracheal (IT) instillation of saline; SB, injected with saline (placebo) and then receiving IT instillation of bleomycin; PB, treated with plasmid only, without bacterial genome, and then receiving IT instillation of bleomycin; and BB, treated with the vaccine and then receiving IT instillation of bleomycin. Bleomycin was instilled 15 days after the last immunization, and the animals were killed six weeks thereafter. The left and right lungs were removed, the former for morphological analysis and the latter for hydroxyproline measurements. Results: The proportion of deaths within the first 48 h after the IT instillation (deaths attributed to the surgical procedure) was higher in the SB group than in the SS group (57.7% vs. 11.1%). The mean area of pulmonary interstitial septa was greater in the SB and PB groups (53.1 ± 8.6% and 53.6 ± 9.3%, respectively) than in the SS and BB groups (32.9 ± 2.7% and 34.3 ± 6.1%, respectively). The mean area of interstitial septa stained by picrosirius was greater in the SB, PB and BB groups than in the SS group (8.2 ± 4.9%, 7.2 ± 4.2% and 6.6 ± 4.1%, respectively, vs. 2.0 ± 1.4%). The total hydroxyproline content in the lung was significantly lower in the SS group (104.9 ± 20.9 pg/lung) than in the other groups (SB: 160.4 ± 47.8 pg/lung; PB: 170.0 ± 72.0 pg/lung; and BB: 162.5 ± 39.7 pg/lung). Conclusions: Immunization with the DNA-hsp65 vaccine reduced the deposition of noncollagen matrix in a model of bleomycin-induced lung lesion.

Keywords: Pulmonary fibrosis; Bleomycin; Collagen.

Objectives: Here, we investigated the effects of hyperventilation on acute lung injury (ALI) in spontaneously breathing rats. Methods: Wistar rats were randomized to receive either intraperitoneal lipopolysaccharides (LPS) or saline, and intravenous infusion of NH4Cl (to induce metabolic acidosis and hyperventilation) or saline. Four groups were established: control-control (C-C), control-hyperventilation (C-HV), LPS-control (LPS-C), and LPS-hyperventilation (LPS-HV). Venous blood gases were collected before and after NH4Cl infusion and analyzed to confirm the presence of metabolic acidosis and hyperventilation. After euthanasia, lung injury was assessed using the ALI score, morphometric quantification of perivascular edema, neutrophil counts in the bronchoalveolar lavage, and mRNA expression of biological markers in the lung tissue. Results: Hyperventilation induced inflammatory lung injury in previously healthy lungs and exacerbated injuries previously induced by LPS (ALI score: C-C=0.14 [IQR 0.12; 0.14]; C-HV=0.36 [IQR 0.31; 0.37]; LPS-C=0.51 [IQR 0.50; 0.54]; LPS-HV=0.58 [IQR 0.56; 0.62]; p<0.01). Perivascular edema, neutrophil counts in bronchoalveolar lavage, and amphiregulin mRNA expression were higher in the LPS-HV group compared to the control group. Conclusions: Hyperventilation increased inflammatory injury in rats with ALI during spontaneous ventilation. These results suggest that the impact of vigorous spontaneous breathing efforts on worsening inflammatory lung injury warrants further investigation.

Keywords: acute lung injury, acute respiratory distress syndrome, spontaneous breathing, hyperventilation, lung injury.

Objective: To investigate the effects of N-acetylcysteine (NAC) and pentoxifylline in a model of remote organ injury after hind-limb ischemia/reperfusion (I/R) in rats, the lungs being the remote organ system. Methods: Thirty-five male Wistar rats were assigned to one of five conditions (n = 7/group), as follows: sham operation (control group); hind-limb ischemia, induced by clamping the left femoral artery, for 2 h, followed by 24 h of reperfusion (I/R group); and hind-limb ischemia, as above, followed by intraperitoneal injection (prior to reperfusion) of 150 mg/kg of NAC (I/R+NAC group), 40 mg/kg of pentoxifylline (I/R+PTX group), or both (I/R+NAC+PTX group). At the end of the trial, lung tissues were removed for histological analysis and assessment of oxidative stress. Results: In comparison with the rats in the other groups, those in the I/R group showed lower superoxide dismutase activity and glutathione levels, together with higher malondialdehyde levels and lung injury scores (p < 0.05 for all). Interstitial inflammatory cell infiltration of the lungs was also markedly greater in the I/R group than in the other groups. In addition, I/R group rats showed various signs of interstitial edema and hemorrhage. In the I/R+NAC, I/R+PTX, and I/R+NAC+PTX groups, superoxide dismutase activity, glutathione levels, malondialdehyde levels, and lung injury scores were preserved (p < 0.05 for all). The differences between the administration of NAC or pentoxifylline alone and the administration of the two together were not significant for any of those parameters (p > 0.05 for all). Conclusions: Our results suggest that NAC and pentoxifylline both protect lung tissue from the effects of skeletal muscle I/R. However, their combined use does not appear to increase the level of that protection.

Keywords: Skeletal muscle; Ischemia; Reperfusion injury; Lung injury; Acetylcysteine; Pentoxifylline.

Small animal models are particularly suitable for lung preservation studies, because they are simple and cost-effective. This brief communication focuses on the technical description of an ex vivo lung perfusion model in rats by means of a commercially available apparatus, which was the first to be installed in a thoracic surgery research laboratory in Brazil. The model and its preparation, together with its applications for lung preservation studies, are described in detail. All technical details can also be seen in a video posted on the website of the Brazilian Journal of Pulmonology.

Keywords: Lung transplantation; Reperfusion injury; Rats; Models, animal.

Objective: Brain death (BD) triggers important hemodynamic and inflammatory alterations, compromising the viability of organs suitable for transplantation. To better understand the mi-crocirculatory alterations in donor lungs caused by BD. The present study investigated the pul-monary microcirculation in a rodent model of BD via intravital microscopy. Methods: Male Wistar rats were anaesthetized and mechanically ventilated. They were trepanned and BD was induced through the increase in intracranial pressure. As control group, sham-operated (SH) rats were trepanned only. In both groups, expiratory O2 and CO2 were monitored and after three hours, a thoracotomy was performed, and a window was created to observe the lung surface using an epi-fluorescence intravital microscopy. Lung expression of intercellular adhesion molecule (ICAM)-1 and endothelial nitric oxide synthase (eNOS) was evaluated by immunohistochemistry, and cytokines were measured in lung samples. Results: Three hours after the surgical proce-dures, pulmonary perfusion was 73% in the SH group. On the other hand, BD animals showed an important decrease in organ perfusion to 28% (p = 0.036). Lung microcirculatory compromise after BD induction was associated with an augmentation of the number of leukocytes recruited to lung tissue, and with a reduction in eNOS expression and an increase in ICAM-1 expression on lung endothelial cells. BD rats showed higher values of expiratory O2 and lower values of CO2 in comparison with SH animals after three hours of monitoring. Conclusion: Data presented showed that BD triggers an important hypoperfusion and inflammation in the lungs, compromis-ing the donor pulmonary microcirculation

Keywords: Brain death; Inflammation; Intravital microscopy; Lung microcirculation.

We evaluated the effect of aminoguanidine on pulmonary oxidative stress and lung structure in an experimental model of diabetes mellitus. Thiobarbituric acid reactive substances (TBARS), histology and arterial blood gases were evaluated in animals with diabetes mellitus (DM group), animals with diabetes mellitus treated with aminoguanidine (DM+AG group), and controls. The TBARS levels were significantly higher in the DM group than in the control and DM+AG groups (2.90 ± 1.12 vs. 1.62 ± 0.28 and 1.68 ± 0.04 nmol/mg protein, respectively), as was PaCO2 when compared with that of the control group (49.2 ± 1.65 vs. 38.12 ± 4.85 mmHg), and PaO2 was significantly higher in the control group (104.5 ± 6.3 vs. 16.30 ± 69.48 and 97.05±14.02 mmHg, respectively). In this experimental model of diabetes mellitus, aminoguanidine reduced oxidative stress, structural tissue alterations, and gas exchange.

Keywords: Oxidative stress; Diabetes mellitus, experimental; Lung.