Mutations in myocilin result in ocular hypertension, likely due to decreased drainage of aqueous humor through the trabecular meshwork. Since less myocilin is found in the aqueous humor of those with disease-causing mutations, understanding myocilin's role in the aqueous humor is of clinical importance. Recently, myocilin was shown to exit cultured trabecular meshwork cells in association with shed vesicles called exosomes. To examine relevance of this finding in a physiological setting, the present study examined three different types of ocular samples for the presence of myocilin-associated exosomes. Using differential centrifugation steps, we found myocilin associated with exosomes isolated from effluent collected from human anterior segments in organ culture and aqueous humor obtained from human cadaveric eyes or from patients undergoing excisional surgery. Similar to results with cultured cells, myocilin associated predominately with exosomes in fresh samples, appeared mostly soluble at later times, and had biochemical properties (density of 1.13-1.19 g/ml in linear sucrose gradient) similar to those characteristics of exosomes. These data indicate that exosomes are present and may facilitate the transport of myocilin into the extracellular space of human ocular cells.

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Purpose: The morphometry of the pulmonary acini in the murine (C57Bl/6) lung were studied using high resolution microCT (HRµCT) scans. Previous studies investigated the morphometry of the acinus of rats and rabbits using silicon rubber casts of the lungs [Weibel et al, 1987] and set a standard for morphologic parameters of the acinus. New technological innovations allow non−destructive sub−sample (3D) of the lung with 1−2µm/voxel. Methods: Preparation: Lungs were fixed in situ via instillation using a Heitzman solution. Lungs were excised and dried for radiographic assessment. Imaging: An XRadia MicroCT scanner (microXCT), capable of ∼1µm/voxel was used for non−destructive 3D image acquisition within the fixed lungs. Morphometry: Following a whole lung scan (50µm/voxel) for determining sample locations within the lung, a HRµCT scan was gathered. Intraacinar airways were segmented from within the HRµCT imaged volume. From this we calculate the following parameters similar to microscopic assessment of Weibel et al.: volume of acinus; branching pattern, segment lengths, inner and outer diameter of acinar airways; number of terminal alveolar sacs; acinar airway pathlength distribution.[figure1]Results and Conclusions: Non−destructive imaging allows for partitioning parenchyma into individual acini and assess their morphometry quantitatively. Our future goals are to characterize the normal murine lung across strains. This abstract is funded by: NIH R01−HL−080285. Am J Respir Crit Care Med 179;2009:A1055 Online Abstracts Issue

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