In vivo microscopy in a porcine model of acute lung injury.

Regional inhomogeneity and alveolar mechanics in a porcine model of acute lung injury (ALI) was evaluated using confocal laser scanning microscopy (CLSM). CLSM was performed through thoracic windows of the upper and lower lobes. Image quantification was conducted by use of a volume air index (VAI). Twelve anesthetized, mechanically ventilated pigs were randomized to non-injury (control group, n = 6) or ALI induced by surfactant depletion (ALI group, n = 6). CLSM was performed at baseline, after 1 h at 5 mbar and after 2 h at 15 mbar positive end-expiratory pressure (PEEP). Haemodynamics, respiratory mechanics and calculation of pulmonary ventilation-perfusion distribution by MIGET were determined. At baseline, VAI was not different. In the upper lobes, VAI significantly decreased in ALI compared to control group, with no changes after PEEP application. In the lower lobes, VAI significantly decreased in ALI compared to control group. Incremental PEEP significantly increased VAI in ALI, but not in control group. Haemodynamics were significantly compromised in the ALI group. A significant deterioration in oxygenation and ventilation-perfusion distribution could be seen being restored after PEEP adjustment. The VAI may help to assess regional inhomogeneity of the acutely injured lung

Methods for quantitative evaluation of alveolar structure during in vivo microscopy

Abstract In vivo fibred confocal laser scanning microscopy allows an evaluation of differences in alveolar mechanics between healthy and acutely injured lungs during mechanical ventilation. The aim of this study was to develop new methods for a quantitative analysis of microscopic images in a murine model of experimental acute lung injury (ALI) and to assess the methods' portability to a large animal model. Differences observed in ALI compared to healthy lungs were: reduction of air-filled areas, increase of heterogeneity and increase of shape irregularity. Three indices were developed: the volume air index (VAI) applies an integral over specific signal intensities, the heterogeneity index (HI) and the Heywood circularity index (CI) comprise variances in size and shape of alveolar structures. The differences between healthy and ALI conditions were found to be significant for all of the used indices (VAI: 0.648 vs. 0.443 (p < 0.05), HI: 0.852 vs. 1.348 (p < 0.001) and CI: 1.56 vs. 1.66 (p < 0.001)). The portability of these algorithms to a porcine model was confirmed reaching similar results (VAI: 0.50 vs. 0.35, p < 0.05; HI: 0.62 vs. 1.83, p < 0.05; CI: 1.56 vs. 1.63, p < 0.001). VAI, HI and CI may help to quantify microscopic images of changes in alveolar structure after experimental ALI

Comparison of two in vivo microscopy techniques to visualize alveolar mechanics

OBJECTIVE: In conventional in vivo microscopy, a three dimensional illustration of tissue is lacking. Concerning the microscopic analysis of the pulmonary alveolar network, surgical preparation of the thorax and fixation of the lung is required to place the microscope's objective. These effects may have influence on the mechanical behaviour of alveoli. Relatively new methods exist for in vivo microscopy being less invasive and enabling an observation without fixation of the lung. The aim of this study was to compare a fibered confocal laser scanning microscopy (FCLSM) with optical coherence tomography (OCT) in a mouse and a rabbit model. Moreover, FCLSM was also used endoscopically in the rabbit model. METHODS: Smallest possible thoracic windows were excised at the lower margin of the upper right lung lobe and an interpleural catheter inserted before re-coverage with a transparent membrane foil. The OCT-scanner was positioned by a motor driven translation stage. The imaging was gated to endinspiratory plateau. For CLSM, Fluorescein 0.1% was given into the central venous streak line. The confocal probe with a diameter of 650 microm was carefully positioned at the very same lung region. Images were directly recorded real-time and the observed region qualitatively compared with FD-OCT images. Additionally, in the rabbit model, CLSM was used endoscopically under bronchoscopic sight control. In a postprocessing analysis, images taken were analyzed and compared by using an "air index" (AI). RESULTS: In the mouse model, the very same region could be re-identified with both techniques. Concerning alveolar shape and size, qualitatively comparable images could be gained. The AI was 40.5% for the OCT and 40.1% for the CLSM images. In the rabbit, even an endoscopic view on alveoli was possible. Likewise AI was 43.2% for CLSM through the thoracic window and 43.6% from endoscopically. For the OCT an AI of 44.6% was analysed in the rabbit model. CONCLUSIONS: Both FD-OCT and CLSM provide high-resolution images of alveolar structure giving depth information that is beneficial to conventional microscopy. CLSM also facilitates endoscopic view on alveoli being well comparable to images gained through a thoracic window

Enantioselective Alkenylation via Nickel-Catalyzed Cross-Coupling with Organozirconium Reagents

A new family of organometallic compounds, organozirconium reagents, are shown to serve as suitable partners in cross-coupling reactions of (activated) secondary alkyl electrophiles. Thus, the first catalytic method for coupling secondary α-bromoketones with alkenylmetal reagents has been developed, specifically, a mild, versatile, and stereoconvergent carbon−carbon bond-forming process that generates potentially labile β,γ-unsaturated ketones with good enantioselectivity.National Institute of General Medical Sciences (U.S.) (grant R01-GM62871)Novartis (Firm)Merck Research Laboratorie