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Extracellular vesicles released in response to cigarette smoke might trigger chronic obstructive pulmonary disease, but engineered versions could be a treatment. Extracellular vesicles released in response to cigarette smoke might trigger chronic obstructive pulmonary disease, but engineered versions could be a treatment., Author(s): Jyoti Madhusoodanan Author Affiliations: The therapeutic potential of exosomes Irfan Rahman exposes cells to smoke as part of research into exosomes and COPD. [see PDF for image] Credit: Irfan [...]

The dynamics of fluid vesicles and red blood cells (RBCs) in cylindrical capillary flow is studied by using a three-dimensional mesoscopic simulation approach. As flow velocity increases, a model RBC is found to transit from a nonaxisymmetric discocyteto an axisymmetric parachute shape (coaxial with the flow axis), while a fluid vesicle is found to transit from a discocyte to a prolate ellipsoid. Both shape transitions reduce the flow resistance. The critical velocities of the shape transitions are linearly dependent on the bending rigidity and on the shear modulus of the membrane. Slipper-like shapes of the RBC model are observed around the transition velocities. Our results are in good agreement with experiments on RBCs. mesoscale hydrodynamics simulation | microfluidics | shape transformations

The study of lung emphysema dates back to the beginning of the 17th century. Nevertheless, a number of important questions remain unanswered because a quantitative localized characterization of emphysema requires knowledge of lung structure at the alveolar level in the intact living lung. This information is not available from traditional imaging modalities and pulmonary function tests. Herein, we report the first in vivo measurements of lung geometrical parameters at the alveolar level obtained with [sup.3]He diffusion MRI in healthy human subjects and patients with severe emphysema. We also provide the first experimental data demonstrating that [sup.3]He gas diffusivity in the acinus of human lung is highly anisotropic. A theory of anisotropic diffusion is presented. Our results clearly demonstrate substantial differences between healthy and emphysematous lung at the acinar level and may provide new insights into emphysema progression. The technique offers promise as a clinical tool for early diagnosis of emphysema.

Surfactant protein D (SP-D) is one of two collectins found in the pulmonary alveolus. On the basis of homology with other collectins, potential functions for SP-D include roles in innate immunity and surfactant metabolism. The SP-D gene was disrupted in embryonic stem cells by homologous recombination to generate mice deficient in SP-D. Mice heterozygous for the mutant SP-D allele had SP-D concentrations that were approximately 50% wild type but no other obvious phenotypic abnormality. Mice totally deficient in SP-D were healthy to 7 months but had a progressive accumulation of surfactant lipids, SP-A, and SP-B in the alveolar space. By 8 weeks the alveolar phospholipid pool was 8-fold higher than wild-type littermates. There was also a 10-fold accumulation of alveolar macrophages in the null mice, and many macrophages were both multinucleated and foamy in appearance. Type II cells in the null mice were hyperplastic and contained giant lamellar bodies. These alterations in surfactant homeostasis were not associated with detectable changes in surfactant surface activity, postnatal respiratory function, or survival. The findings in the SP-Ddeficient mice suggest a role for SP-D in surfactant homeostasis.

A surface fluorescence method to quantify transalveolar transport of water, protons and solutes in lungs gives sensitive, time resolved biophysical data from intact organs. The lungs are removed and perfused via the pulmonary artery. The airspace is filled with a solution containing a membrane impermeant fluorescent indicator. Fluorescence signals from the lung surfaces originate from the indicator and provide data on intraalveolar fluid composition. The application of this method shows that the mouse lung has high water permeability which may involve water channels.

The cloning and characterization of the gene for non-clathrin-coat protein alpha (alpha-COP) from Saccharomyces cerevisiae reveals that it has a molecular weight of 135,500 and the presence of forty repeat motifs. The structure is similar to the bovine alpha-COP. Proteins when synthesized from the endoplasmic reticulum have to be transported to the plasma membrane. This occurs through vesicles with the involvement of a coat protein structure in mammals, made up of ADP-ribosylation factor and a coatmer, a complex of seven proteins.

Byline: Pankaj. Saxena, Suvitesh. Luthra, Rajinder. Dhaliwal, Surinder. Rana, Digambar. Behera Background: This study evaluates changes in pulmonary functions before and after mitral valve replacement (MVR). Materials and Methods: Twenty-five [...]

Although vesicles are found in secretory tissues of both invertebrates and vertebrates, their role in fluid transport remains unclear. The Malpighian tubules (Mt) of Acheta domesticus exhibit extensive vacuolation in response to secretagogues. When Mts are treated with cAMP, which causes a doubling in secretion rate, [is greater than] 12% of the cell volume is occupied by vesicles, compared with [is less than] 1% in unstimulated controls. Using Lucifer Yellow CH, a fluid-phase fluorescent marker, we have demonstrated that the extracellular fluid enters the Mt cells via endocytosis. The dye also appears in the secreted urine, showing that it does move completely across the Mt cells. At present we are using electron-dense markers to track vesicle movement in order to show whether the transcellular movement is indeed transcytosis or whether some other mechanism is involved. Supported by USDA-CREEF grant 9501834.