Normal Rabbit Lungs Research Articles

Heterogeneous Response in Rabbit Fetal Diaphragmatic Hernia Lungs After Tracheal Occlusion

BackgroundFetal tracheal occlusion (TO) is an experimental therapeutic approach to stimulate lung growth in the most severe congenital diaphragmatic hernia (CDH) cases. We have previously demonstrated a heterogeneous response of normal fetal rabbit lungs after TO with the appearance of at least two distinct zones. The aim of this study was to examine the fetal lung response after TO in a left CDH fetal rabbit model. MethodsFetal rabbits at 25 d gestation underwent surgical creation of CDH followed by TO at 27 d and harvest on day 30. Morphometric analysis, global metabolomics, and fluorescence lifetime imaging microscopy (FLIM) were performed to evaluate structural and metabolic changes in control, CDH, and CDH + TO lungs. ResultsRight and left lungs were different at the baseline and had a heterogeneous pulmonary growth response in CDH and after TO. The relative percent growth of the right lungs in CDH + TO was higher than the left lungs. Morphometric analyses revealed heterogeneous tissue-to-airspace ratios, in addition to size and number of airspaces within and between the lungs in the different groups. Global metabolomics demonstrated a slower rate of metabolism in the CDH group with the left lungs being less metabolically active. TO stimulated metabolic activity in both lungs to different degrees. FLIM analysis demonstrated local heterogeneity in glycolysis, oxidative phosphorylation (OXPHOS), and FLIM “lipid-surfactant” signal within and between the right and left lungs in all groups. ConclusionsWe demonstrate that TO leads to a heterogeneous morphologic and metabolic response within and between the right and left lungs in a left CDH rabbit model.

99mTc-radiolabeled composites enabling in vivo imaging of arterial dispersal and retention of microspheres in the vascular network of rabbit lungs, liver, and liver tumors.

PurposeSelective internal radiation therapy (SIRT) is an effective treatment option for liver tumors, using Y-90-loaded polymer microspheres that are delivered via catheterization of the hepatic artery. Since Y-90 is a beta emitter and not conveniently imaged by standard clinical instrumentation, dosimetry is currently evaluated in each patient using a surrogate particle, 99mTechnetium-labeled macroaggregated albumin (99mTc-MAA). We report a new composite consisting of 99mTc-labeled nanoparticles attached to the same polymer microspheres as used for SIRT, which can be imaged with standard SPECT.MethodsCarbon nanoparticles with an encapsulated core of 99mTc were coated with the polycation protamine sulfate to provide electrostatic attachment to anionic polystyrene sulfonate microspheres of different sizes (30, 12, and 8 µm). The in vivo stability of these composites was determined via intravenous injection and entrapment in the capillary network of normal rabbit lungs for up to 3 hours. Furthermore, we evaluated their biodistribution in normal rabbit livers, and livers implanted with VX2 tumors, following intrahepatic artery instillation.ResultsWe report distribution tests for three different sizes of radiolabeled microspheres and compare the results with those obtained using 99mTc-MAA. Lung retention of the radiolabeled microspheres ranged from 72.8% to 92.9%, with the smaller diameter microspheres showing the lowest retention. Liver retention of the microspheres was higher, with retention in normal livers ranging from 99.2% to 99.8%, and in livers with VX2 tumors from 98.2% to 99.2%. The radiolabeled microspheres clearly demonstrated preferential uptake at tumor sites due to the increased arterial perfusion produced by angiogenesis.ConclusionWe describe a novel use of radiolabeled carbon nanoparticles to generate an imageable microsphere that is stable in vivo under the shear stress conditions of arterial networks. Following intra-arterial instillation in the normal rabbit liver, they distribute in a distinct segmented pattern, with the smaller microspheres extending throughout the organ in finer detail, while still being well retained within the liver. Furthermore, in livers hosting an implanted VX2 tumor, they reveal the increased arterial perfusion of tumor tissue resulting from angiogenesis. These novel composites may have potential as a more representative mimic of the vascular distribution of therapeutic microspheres in patients undergoing SIRT.

A synthetic tryptophan metabolite reduces hemorrhagic area and inflammation after pulmonary radiofrequency ablation in rabbit nonneoplastic lungs

The purpose of this study was to determine the effect of a synthetic tryptophan metabolite, tranilast [N-(3,4-dimethoxycinnamoyl)-anthranilic acid], on inflammatory and hemorrhagic areas after pulmonary radiofrequency ablation (RFA) in rabbits. Percutaneous RFA using a 17-gauge LeVeen electrode was performed in normal rabbit lungs. The rabbits were divided into tranilast-treated (300mg/kg/day, orally) and control groups (n=24/group). The effects of tranilast were evaluated using multidetector-row computed tomography (CT), histology, and immunohistochemistry immediately after RFA on days 1, 7, 14, and 28. Oral administration of tranilast significantly reduced the size of ablated lesions assessed using CT and histology on days 7 and 14. Furthermore, it reduced the hemorrhagic areas on day 7 and inflammatory areas on day 14, but did not affect the areas of coagulation necrosis on days 1, 7, 14, and 28. Immunohistochemical analysis showed an increase in the ratio of CD163-positive macrophage areas to rabbit macrophage (RAM11)-positive pan-macrophage areas and a decrease in the number of nuclear factor-κB-positive nuclei and CD31-positive microvessels in the tranilast group on days 7 and/or 14. The results suggest that tranilast modulates the repair process after pulmonary RFA through macrophage accumulation, suppression of inflammation, and angiogenesis.

Ex Vivo Lung Sonography: Morphologic-Ultrasound Relationship

Ultrasound (US) interstitial syndrome is a sonographic lung pattern characterized by the presence of acoustic artifacts (B-lines and white lung). The purpose of this study was to demonstrate how interstitial syndrome is determined by acoustic interactions in lungs of variable density and in healthy organs deflated to a nonphysiologic level of density. Normal rabbit lungs were studied ex vivo by US at varying known degrees of inflation, and their histologic appearances were described. In this experimental setting, US interstitial syndrome recognizes a mechanism related to tissue density or porosity. Artifacts (B-lines and white lung) appear in the normal rabbit lung through air-dependent increases in density. As in pathologic conditions, US interstitial syndrome can be reproduced in histologically normal lungs that are deflated to a critical level (>0.45 g/mL) of density, which is not achievable under physiologic conditions.

New images, new insights for VILI

prioritization of high-volume vs. low-volume mechanisms of ventilator-induced lung injury (VILI) is an issue that is often discussed and debated in clinical ventilator management. Abundant laboratory studies ([7][1]), as well as several prominent clinical studies ([1][2], [3][3], [14][4], [19][5]),

Pretreatment with atorvastatin attenuates lung injury caused by high-stretch mechanical ventilation in an isolated rabbit lung model

We hypothesized that pretreatment with atorvastatin improves alveolar capillary permeability and hemodynamics and, thus, confers protection against lung injury caused by high-stretch mechanical ventilation. Twenty-four isolated sets of normal rabbit lungs were utilized. Treated animals received atorvastatin (20 mg/kg body weight/day by mouth) for 3 days before surgery. Lungs were perfused constantly (300 mL/min) and ventilated for 1 hr with pressure-control ventilation at either 23 (high pressure; resulting in tidal volume approximately 22 mL/kg) or 11 (low pressure; tidal volume approximately 10 mL/kg) cm H2O peak inspiratory pressure and positive end-expiratory pressure of 3 cm H2O. Four groups were examined: high pressure-no statin, high pressure-statin pretreatment, low pressure-no statin, and low pressure-statin pretreatment. The high-pressure-no statin group sustained more damage than the low-pressure groups. In high-pressure groups, lungs of statin-pretreated vs. no statin-pretreated animals sustained a significantly lower increase in ultrafiltration coefficient (an accurate marker of alveolar capillary permeability; high-pressure-statin pretreatment vs. high-pressure-no statin, -0.013 +/- 0.017 g/min/mm Hg/100g vs. 1.723 +/- 0.495 g/min/mm Hg/100g; p < .001), lower weight gain (i.e., less edema formation; 4.62 +/- 1.50 grams vs. 17.75 +/- 4.71 grams; p = .005), improved hemodynamics (i.e., lower increase in mean pulmonary artery pressure; 0.56 +/- 0.51 mm Hg vs. 5.62 +/- 1.52 mm Hg; p = .04), lower protein concentration in bronchoalveolar lavage fluid (p < .001), and fewer histologic lesions (p = .013). Apoptosis of lung parenchyma cells was not different (p = .97). There was no difference between low-pressure-statin pretreatment and low-pressure-no statin groups regarding these outcomes. In this model, atorvastatin improves alveolar capillary permeability and hemodynamics and, thus, attenuates lung injury caused by high-stretch mechanical ventilation.

Chest wall temperature during radiofrequency ablation in a normal rabbit lung model

The aim of this study was to examine the actual temperature during lung radiofrequency ablation (RFA) and pathological changes due to thermal damage in the pleural tissue of the chest wall in a rabbit model. The study was conducted on 14 Japanese white rabbits with normal lungs. Under computed tomography guidance, the electrode with a 2-cm expandable tip was inserted into the lower lung lobe and positioned so the tip of the needle touched the thoracic wall upon expansion. A thermometer was inserted 5 mm lateral to the point of electrode insertion. RFA was applied at 30 W (n = 7) or 15 W (n = 7) until maximum impedance (i.e., roll-off) or for 4 min at the longest. Local tissue temperature was recorded. The chest wall was dissected out immediately after RFA for histological examination. The mean (+/- SD) maximum tissue temperature at 30 W (86.7 degrees +/- 10.0 degrees C) was not significantly different from that at 15 W (82.1 degrees +/- 6.2 degrees C). The mean ablation time to increase tissue temperature to 50 degrees , 60 degrees , and 70 degrees C was faster at 30 W (13, 27, and 49 s, respectively) than at 15 W (13, 56, and 115 s, respectively) (P < 0.05). Histological examination showed pleural sloughing at the point of needle insertion and ring-shaped thermal injury in the chest wall. With rabbit lung RFA near the chest wall, ablation immediately below the pleura resulted in a rise of local tissue temperature to >80 degrees C and thermal injury.

Converging Stereotactic Radiotherapy Using Kilovoltage X-Rays: Experimental Irradiation of Normal Rabbit Lung and Dose–Volume Analysis With Monte Carlo Simulation

To validate the feasibility of developing a radiotherapy unit with kilovoltage X-rays through actual irradiation of live rabbit lungs, and to explore the practical issues anticipated in future clinical application to humans through Monte Carlo dose simulation. A converging stereotactic irradiation unit was developed, consisting of a modified diagnostic computed tomography (CT) scanner. A tiny cylindrical volume in 13 normal rabbit lungs was individually irradiated with single fractional absorbed doses of 15, 30, 45, and 60 Gy. Observational CT scanning of the whole lung was performed every 2 weeks for 30 weeks after irradiation. After 30 weeks, histopathologic specimens of the lungs were examined. Dose distribution was simulated using the Monte Carlo method, and dose-volume histograms were calculated according to the data. A trial estimation of the effect of respiratory movement on dose distribution was made. A localized hypodense change and subsequent reticular opacity around the planning target volume (PTV) were observed in CT images of rabbit lungs. Dose-volume histograms of the PTVs and organs at risk showed a focused dose distribution to the target and sufficient dose lowering in the organs at risk. Our estimate of the dose distribution, taking respiratory movement into account, revealed dose reduction in the PTV. A converging stereotactic irradiation unit using kilovoltage X-rays was able to generate a focused radiobiologic reaction in rabbit lungs. Dose-volume histogram analysis and estimated sagittal dose distribution, considering respiratory movement, clarified the characteristics of the irradiation received from this type of unit.

Pretreatment with atorvastatin ameliorates lung injury caused by high-pressure/high-tidal-volume mechanical ventilation in isolated normal rabbit lungs

Previous animal studies revealed that administration of statins ameliorates lung injury following endotoxin exposure or ischemia-reperfusion. In this experiment, we endeavored to investigate whether pretreatment with atorvastatin confers protection from lung injury caused by high-pressure/high-tidal-volume ventilation.

Experimental stereotactic irradiation of normal rabbit lung: computed tomographic analysis of radiation injury and the histopathological features

The aim of this study was to establish an animal experimental model of pulmonary stereotactic irradiation and clarify the morphological patterns of pulmonary radiation injury with computed tomography and the histopathological features. Tiny spherical regions in the lungs of seven anesthetized rabbits were irradiated stereotactically with a single fractional dose of 21-60 Gy. Subsequently, the irradiated lungs were observed biweekly with computed tomography (CT) for 24 weeks. Radiation injury of the lung was examined histopathologically in one specimen. Localized hypodense changes were observed 7-15 weeks after irradiation in three rabbits irradiated with 60 Gy, and the findings persisted beyond that time. The electron density ratios in the lung fields obtained from the CT images were shown to be decreasing, corresponding to the hypodensity changes. No clear increased density opacity was observed in any rabbit in the 60-Gy irradiated group. Severe localized fibrotic change was observed in the histopathological specimens. Specific localized hypodensity changes were found in only three rabbits irradiated with 60 Gy, the highest dose we employed.

Expression of retinoid receptors during rabbit lung development

Rabbit lung is often used to study the pathophysiology of some congenital anomalies affecting the lung because its development is very comparable with that of human. Retinoids and the molecular transducers of the retinoic signal play a crucial role in mammalian lung development. In the rabbit, the molecular retinoic pathway has so far been poorly studied. As a first step in elucidating this process, we aimed to identify the retinoic acid receptors (RARs) and retinoid X receptors (RXRs). We cloned a part of the nuclear receptors (RARs and RXRs), and we used reverse transcription - polymerase chain reaction (RT-PCR) and immunohistochemistry assays to demonstrate the presence of RAR (α,β) and RXR (α, β) at all stages of rabbit lung development. Our results initiate further analysis into the molecular and genetic functions of retinoids during normal and pathological rabbit lung development including the surgical model of congenital diaphragmatic hernia.

1428 POSTER Experimental model of radiation sequelae induced with single stereotactic irradiation to normal rabbit lung. computed tomographical analysis

Fractionated stereotactic radiotherapy (FSRT) combines the precision of stereotactic positioning with the radiobiologic advantage of dose fractionation.From June 1997 to June 2001, 30 patients with cavernous sinus meningiomas were treated with FSRT using fixed noncoplanar conformal fields. Patient skull fixation was achieved using the BrainLAB mask (20 patients) or Beverly frame (10 patients). The Cosman-Roberts-Wells coordinate frame was used for stereotactic space definition. In selected cases before 1999, and in all cases afterward, gadolinium-enhanced MRI for image fusion was performed. The median radiation dose was 52 Gy, with a daily fraction of 2 Gy. Patients were regularly followed up analyzing symptoms, tumor progression, and side effects. Neurocognitive function was evaluated retrospectively for 26 patients using Mini-Mental State Examination.Median follow-up period was 50 months (range, 28.2-74.5 months). Preexisting neurologic symptoms improved in 50% of the patients and worsened in 2 patients. Only 2 patients progressed and the actuarial local progression free survival was 93% at 4 years. Tolerance was good with 2 cases of late radiation toxicity which consisted of moderate short-term memory loss and dysphasia in one case and neuropsychologic deficit with seizures in the other. Postradiotherapy Mini-Mental State Examination results showed a median score of 28 (range, 16-30).Fractionated stereotactic radiotherapy is a high-precision technique. It is safe and feasible in the primary and adjuvant treatment of cavernous sinus meningiomas. Fractionated stereotactic radiotherapy allowed local control in more than 90% of patients.

Neutrophil depletion attenuates interleukin-8 production in mild-overstretch ventilated normal rabbit lung.

Acute lung injury induced by lung overstretch is associated with neutrophil influx, but the pathogenic role of neutrophils in overstretch-induced lung injury remains unclear. To assess the contribution of neutrophils, we compared the effects of noninjurious large tidal volume (Vt) ventilation on lungs in normal and neutrophil-depleted animals. Research animal laboratory. Twenty-six male Japanese white rabbits. Animals were mechanically ventilated for 4 hrs with one of the three following protocols: large Vt (20 mL/kg), small Vt (8 mL/kg), and large Vt (20 mL/kg) with neutrophil depletion achieved by a single dose of vinblastine injection (0.75 mg/kg) intravenously 4 days before the experiment. Large Vt ventilation produced alveolar neutrophil influx compared with low Vt (p =.002) without evidence of edema or increased epithelial permeability. The neutrophil influx was accompanied by increases in interleukin-8 in bronchoalveolar lavage fluid (p =.04). Immunohistochemistry of large Vt lungs showed increased interleukin-8 staining in bronchial epithelial cells, alveolar epithelium, alveolar macrophages, and smooth muscles of pulmonary vessels. Neutrophil depletion attenuated the interleukin-8 increase in the lung. Large Vt did not increase plasma interleukin-8 or tumor necrosis factor-alpha in plasma and bronchoalveolar lavage fluid. No expression of p-selectin or intercellular adhesion molecule-1 was observed. Cyclic overstretching of normal rabbit lungs with noninjurious large Vt produced neutrophil influx and interleukin-8 increase in bronchoalveolar lavage fluid. Production of pulmonary interleukin-8 by lung overstretch might require the interaction between resident lung cells and migrated neutrophils. This study suggests that large Vt ventilation potentiates the predisposed, subclinical lung injury, such as nosocomial pneumonia or aspiration of gastric contents.

Heliox enhances carbon dioxide clearance from lungs of normal rabbits during low bias flow oscillation

To evaluate carbon dioxide clearance in normal rabbits during high-frequency oscillatory ventilation with helium-oxygen mixtures by using a low bias flow oscillation (LBFO) system designed to conserve expensive gas. A prospective, paired-controlled, interventional, in vivo animal laboratory study. Animal laboratory of a health science university. Twelve New Zealand White rabbits. Juvenile rabbits were anesthetized, paralyzed, and ventilated through a tracheostomy. LBFO was performed with a modified high-frequency oscillatory ventilation circuit that uses low bias flow (100 mL/kg) and a soda lime cartridge to clear carbon dioxide. LBFO-heliox trials were performed with 20%, 40%, 50%, 60%, and 70% helium (balanced with oxygen) for 30 mins. Each heliox trial was preceded by a paired control trial with 40% oxygen and 60% nitrogen for 30 mins. Ventilator settings in control and heliox trials were identical. During the second part of the study, four rabbits were made hypercapnic by decreasing the power (amplitude), and LBFO was performed with 70% helium against paired-control trials of 40% oxygen and 60% nitrogen. Arterial blood gases were measured at 15-min intervals and airway pressure amplitude was recorded. PaCO2 of control and heliox trials, alveolar PO2-PaO2 gradient of control, and 60% helium trials were compared by paired Student's t-test. At constant power, amplitude was unaffected by helium. Helium concentrations of 40%, 50%, 60%, and 70% decreased PaCO2 by 12%, 33%, 36%, and 46%, respectively. Alveolar PO2-PaO2 gradient was decreased by 40% during ventilation with 60% helium. Under hypercapnic conditions, 70% helium decreased PaCO2 by 20%. Helium concentrations > or = 40% facilitate carbon dioxide clearance from lungs of normal rabbits during LBFO. This could be accomplished inexpensively with LBFO due to preservation of heliox when using this device.

The biological effects of multi-electrode radiofrequency ablation on normal rabbit lungs

To study the biological effects of multi-electrode radiofrequency ablation on pulmonary tissues of rabbits. Under the guidance of computer tomograph, electrodes were inserted into right lungs of New Zealand white rabbits and radiofrequency was performed. The biological effects were observed through CT image and microscopy. Coagulative necrosis was found immediately in ablation area after the procedure. On the 7th postradiofrequency ablation day, fibrous tissues appeared in the necrotic lesions. On the 30th postradiofrequency ablation day, bronchial and alveolar epithelium began to proliferate. Within 60 to 90 days after treatments, the necrotic lesions were almost replaced by normal pulmonary tissues. In group with electrodes into the right hilum, time for treating and initial impedance were significantly different from those with electrodes into the peripheral sites of the right-lower lobes (P < 0.01, P < 0.01). Multi-electrode radiofrequency ablation can be safely and effectivly performed in pulmonary tissue and cause coagulative necrosis within a certain extent.

Evaluation of Parameters of Gas Exchange During Partial Liquid Ventilation in Normal Rabbit Lung

Background: The opitmal ventilator setting during partial liquid ventilation(PLV) is controversial. This study investigated the effects of various gas exchange parameters during PLV in normal rabbit lungs in order to aid in the development of an optimal ventilator setting during PLV. Methods: Seven New-Zealand white rabbits were ventilated in pressure-controlled mode with the following settings; tidal volume() 8 mL/kg, positive end-expiratory pressure(PEEP) 4 , inspiratory-to-expiratory ratio(I:E ratio) 1:2, fraction of inspired oxygen() 1.0. The respiration rate(RR) was adjusted to keep between 35~45 mmHg. The ventilator settings were changed every 30 min in the following sequence : (1) Baseline, as the basal ventilator setting, (2) Inverse ratio, I:E ratio 2:1, (3) high PEEP, adjust PEEP to achieve the same mean inspiratory pressure (MIP) as in the inverse ratio, (4) High , 15 mL/kg, (5) high RR, the same minute ventilation (MV) as in the High . Subsequently, the same protocol was repeated after instilling 18 mL/kg of perfluorodecalin for PLV. The parameters of gas exchange, lung mechanics, and hemodynamics were examined. Results: (1) The gas ventilation(GV) group showed no significant changes in the at all phases. The was lower and the pH was higher at the high and high RR phases(p for the PLV was mmHg. This was significantly lower when decreased compared to the baseline for GV which was mmHg(p=0.001). During PLV, the , was significantly higher at the high PEEP( mmHg) and high ( mmHg) phases compared with the baseline phase. However, it did not change significantly during the inverse I:E ratio or the high RR phases. (3) The was significantly lower at high and RR phases for both the GV and PLV. During the PLV, were significantly higher compared to the GV (p and PEEP are important for optimal oxygenation.

Protective effects of hypercapnic acidosis on ventilator-induced lung injury.

To investigate whether respiratory acidosis modulates ventilator-induced lung injury (VILI), we perfused (constant flow) 21 isolated sets of normal rabbit lungs, ventilated them for 20 min (pressure controlled ventilation [PCV] = 15 cm H(2)O) (Baseline) with an inspired CO(2) fraction adjusted for the partial pressure of CO(2) in the perfusate (PCO(2) approximately equal to 40 mm Hg), and then randomized them into three groups. Group A (control: n = 7) was ventilated with PCV = 15 cm H(2)O for three consecutive 20-min periods (T1, T2, T3). In Group B (high PCV/normocapnia; n = 7), PCV was given at 20 (T1), 25 (T2), and 30 (T3) cm H(2)O. The targeted PCO(2) was 40 mm Hg in Groups A and B. Group C (high PCV/hypercapnia; n = 7) was ventilated in the same way as Group B, but the targeted PCO(2) was approximately equal to 70 to 100 mm Hg. The changes (from Baseline to T3) in weight gain (Delta WG: g) and in the ultrafiltration coefficient (Delta K(f) = gr/min/ cm H(2)O/100g) and the protein and hemoglobin concentrations in bronchoalveolar lavage fluid (BALF) were used to assess injury. Group B experienced a significantly greater Delta WG (14.85 +/- 5.49 [mean +/- SEM] g) and Delta K(f) (1.40 +/- 0.49 g/min/cm H(2)O/100 g) than did either Group A (Delta WG = 0.70 +/- 0.43; Delta K(f) = 0.01 +/- 0.03) or Group C (Delta WG = 5.27 +/- 2.03 g; Delta K(f) = 0.25 +/- 0.12 g/min/cm H(2)O/ 100 g). BALF protein and hemoglobin concentrations (g/L) were higher in Group B (11.98 +/- 3.78 g/L and 1.82 +/- 0.40 g/L, respectively) than in Group A (2.92 +/- 0.75 g/L and 0.38 +/- 0.15 g/L) or Group C (5.71 +/- 1.88 g/L and 1.19 +/- 0.32 g/L). We conclude that respiratory acidosis decreases the severity of VILI in this model.

Recombinant human Fas ligand induces alveolar epithelial cell apoptosis and lung injury in rabbits

This study investigated whether recombinant human soluble Fas ligand (rh-sFasL) induces apoptosis of primary type II pneumocytes in vitro and lung injury in vivo. Type II cells isolated from normal rabbit lung expressed Fas on their surface and became apoptotic after an 18-h incubation with rh-sFasL. Fas expression in normal rabbit lungs was localized by immunohistochemistry to alveolar and airway epithelia and alveolar macrophages. The administration of 10 microg of rh-sFasL into the right lungs of rabbits resulted 24 h later in both significantly more bronchoalveolar lavage fluid total protein and significantly more tissue changes compared with those in the left lungs, which received rh-sFasL plus Fas:Ig (a fusion protein that binds and blocks sFasL). Tissue changes included thickening of the alveolar walls, neutrophilic infiltrates, apoptotic (terminal deoxynucleotidyltransferase-mediated dUTP nick end labeling-positive) cells in the alveolar walls, and increased expression of interleukin-8 by alveolar macrophages (as determined by immunohistochemistry). We conclude that the alveolar epithelium of normal rabbits expresses Fas and that sFasL induces lung injury and inflammation in rabbits.

Airway branching morphology of mature and immature rabbit lungs.

The scheme of Horsfield et al. for describing the pulmonary airway tree (J Appl Physiol 52: 21-26, 1982) catalogs each airway according to its order and the difference in order of its two daughters (denoted Delta). Although this scheme captures the natural asymmetry in the airway tree, it is still deterministic, because it assumes that all airways of a given order are the same; yet such variability is extremely important in determining the overall behavior of the lungs. We therefore analyzed complete lung lobes from three mature and two immature rabbits and determined the Horsfield order and Delta of every airway down to the terminal bronchioles. We also measured the diameter of each airway. This allowed us to determine the average structure of the rabbit airway tree, the variation about this average, and also how the structures of mature and immature airway trees compare. We found some variation in branching asymmetry and airway diameter at a given order between animals but no evidence of systematic differences in structure between mature and immature lungs. We found evidence of a difference in the branching structure of the peripheral vs. the central part of the airway tree (the break point being around order 20). We also determined the nature of the variation in Delta and diameter as a function of order, which should be valuable for the development of computer models seeking to encapsulate the naturally occurring regional variation in airway geometry in the normal rabbit lung.

Effects of low volume + ZEEP, low volume + PEEP, low volume and sigh to plasma and BAL MDA levels in normal rabbit lungs

Effects of low volume + ZEEP, low volume + PEEP, low volume and sigh to plasma and BAL MDA levels in normal rabbit lungs