Tracer Diffusion
Mostrando 13-24 de 46 artigos, teses e dissertações.
-
13. Relative roles of gap junction channels and cytoplasm in cell-to-cell diffusion of fluorescent tracers.
Intercellular (tissue) diffusion of molecules requires cytoplasmic diffusion and diffusion through gap junctional (or cell-to-cell) channels. The rates of tissue and cytoplasmic diffusion of fluorescent tracers, expressed as an effective diffusion coefficient, De, and a cytoplasmic diffusion coefficient, Dcyt, have been measured among the developing epiderma
-
14. Diffusion measurement of fluorescence-labeled amphiphilic molecules with a standard fluorescence microscope.
The lateral diffusion of fluorescence-labeled amphiphilic tracer molecules dissolved within a two-dimensional matrix of lipids was measured by continuous illumination of an elongated rectangular region. The resulting spatial concentration profile of unbleached tracer molecules was observed with a standard epifluorescence microscope and analyzed with digital
-
15. Steady-state analysis of tracer exchange across the C5b-9 complement lesion in a biological membrane.
Resealed erythrocyte ghosts have been used to define the kinetics of tracer exchange across the membrane-bound terminal complex of the complement cascade (C5b-9). Under steady-state conditions and at net chemical equilibrium, C5b-9 ghosts showed no significant lysis above control levels as measured by hemoglobin efflux. In 1 mM sucrose at 37 degrees C, [14C]
-
16. Estimates of stratospheric pollution by an analytic model.
With suitable choices of the height profile of eddy diffusion coefficient, the vertical flow of an inert tracer is given by an analytic solution. Odd nitrogen, or NOX, from aircraft exhausts can be regarded as such a tracer, and the amount in the stratosphere resulting from a source of a given strength can be immediately calculated. The resulting destruction
-
17. Binding and diffusion characteristics of 14C EDTA and 99mTc DTPA in respiratory tract mucus glycoprotein from patients with chronic bronchitis.
Measurement of pulmonary clearance of an inhaled aerosol of technetium-99m labelled diethylenetriaminepenta-acetate (DTPA) by external detection methods has been used widely as an index of permeability across alveolar epithelium and bronchial mucosa. To determine the applicability of the tracer to measurement of permeability in the airways the diffusion and
-
18. Tracking neuronal fiber pathways in the living human brain
Functional imaging with positron emission tomography and functional MRI has revolutionized studies of the human brain. Understanding the organization of brain systems, especially those used for cognition, remains limited, however, because no methods currently exist for noninvasive tracking of neuronal connections between functional regions [Crick, F. & Jones
The National Academy of Sciences.
-
19. Single-particle tracking: models of directed transport.
Single-particle tracking techniques make it possible to measure motion of individual particles on the cell surface. In these experiments, individual trajectories are observed, so the data analysis must take into account the randomness of individual random walks. Methods of data analysis are discussed for models combining diffusion and directed motion. In the
-
20. Macromolecular diffusion in crowded solutions.
The effects of crowding on the self or tracer diffusion of macromolecules in concentrated solutions is an important but difficult problem, for which, so far, there has been no rigorous treatment. Muramatsu and Minton suggested a simple model to calculate the diffusion coefficient of a hard sphere among other hard spheres. In this treatment, scaled particle t
-
21. Diffusion behavior of lipid vesicles in entangled polymer solutions.
Dynamic light scattering was used to follow the tracer diffusion of phospholipid/cholesterol vesicles in aqueous polyacrylamide solutions and compared with the diffusive behavior of polystyrene (PS) latex spheres of comparable diameters. Over the range of the matrix concentration examined (Cp = 0.1-10 mg/ml), the diffusivities of the PS spheres and the large
-
22. The Chlamydia trachomatis parasitophorous vacuolar membrane is not passively permeable to low-molecular-weight compounds.
Chlamydia trachomatis is an obligately intracellular bacterial parasite of eucaryotic cells that undergoes a biphasic life cycle within a parasitophorous vacuole (PV) called an inclusion. The parasitophorous vacuolar membrane (PVM) constitutes a barrier between the replicating bacteria and the nutrient-rich environment of the host cytoplasm. To determine whe
-
23. Lateral diffusion in model membranes is independent of the size of the hydrophobic region of molecules.
We have systematically investigated the probe size and shape dependence of lateral diffusion in model dimyristoyl phosphatidylcholine membranes. Linear hydrophobic polymers, which differ in length by an order of magnitude, were used to explore the effect on the lateral diffusion coefficient of hydrodynamic restrictions in the bilayer interior. The polymers e
-
24. Line-scanning microphotolysis for diffraction-limited measurements of lateral diffusion.
Fluorescence microphotolysis was combined with confocal laser-scanning microscopy to yield a method, herein referred to as line-scanning microphotolysis (LINESCAMP), for the measurement of molecular transport at a lateral resolution of approximately 0.34 microns and a temporal resolution of approximately 0.5 ms. A confocal microscope was operated in the line