Showing papers in "Biophysical Journal in 1989"

TL;DR: The results show that the outer cortex of the cell maintains a small persistent tension which creates a threshold pressure below which the cell will not enter the pipet, and the ratio of cortical flow resistance to flow resistance from the cell interior shows that the cortex does not contribute significantly to the total flow resistance.

TL;DR: This work has shown that when the anisotropy ratios of the intracellular and extracellular spaces are not equal, the injection of current into the tissue induces a transmembrane potential that has a complicated spatial dependence, including adjacent regions of depolarized and hyperpolarized tissue.

TL;DR: This work has analyzed the inertialess flow of a liquid-like model cell into a tube at constant suction pressure and determined universal predictions for flow rate scaled by the ratio of excess pressure (above the threshold established by the cortical tension) and core viscosity which is the reciprocal of the dynamic resistance to entry.

TL;DR: Intracellular fluorescent structures were observed that correlated with the distribution of a mitochondrial selective fluorescent probe, the mitochondrial distribution seen in published electron micrographs, and a metabolic digital subtraction image of the cyanide fluorescence transition, consistent with the notion that the blue autofluorescence of rat cardiac myocytes originates from mitochondrial NADH.

TL;DR: The model predicts a relation between tension and voltage at breakdown and this relation is verified experimentally for the three reconstituted membrane systems studied here.

TL;DR: It was found that the pulsed RF field is highly efficient in both cell fusion and cell poration, and in comparison with electro-poration using a DC field, the RF field results in a higher percentage of cells surviving the exposure to the electric field.

TL;DR: The methodology should therefore be applicable to the study of more subtle and specific, biologically induced potential changes in cells, and apply the technique to concomitantly follow, with good time resolution, the mitochondrial and plasma membrane potentials in several cultured cell lines.

TL;DR: The most successful results were obtained when the density of the methylene region was constrained to the value obtained from the wide-angle scattering, and the lipid volume obtained from absolute specific volume measurements.

TL;DR: A new method has been developed to determine the complete orientational order profile of lipid bilayers using 2H-NMR, and reveals in a straightforward way the crucial features of the anisotropic order of the bilayer.

TL;DR: The ionophore properties of magainin I, an antimicrobial and amphipathic peptide from the skin of Xenopus, were investigated in planar lipid bilayers, revealing a weakly voltage-dependent macroscopic conductance which is anion-selective when using large aqueous peptide concentration with lipid bilayer under high voltages.

TL;DR: Electron microscopy showed that VP1 pentamers, which correspond to viral capsomeres, can be self-assembled into a variety of polymorphic aggregates by lowering the pH, adding calcium, or raising the ionic strength.

TL;DR: By using cryo-TEM, a technique which preserves the original microstructure of fluid systems and provides direct images at 1 nm resolution, the vesicle-micelle transition is elucidated and intermediates not known previously in the PC/OG system are identified.

TL;DR: According to this modified procedure, the channel protein and any accessory structures, postulated to be needed for mechanotransduction, can be reconstituted together by this method.

TL;DR: In this article, the curvature elastic modulus (bending stiffness) of stearoyloleoyl phosphatidylcholine (SOPC) bilayer membrane is determined from membrane tether formation experiments.

TL;DR: A lineshape model was devised which allows accurate simulation of single crystal and frozen solution spectra from integer-spin metal centers having large zero-field splittings and is shown to predict an unknown concentration relative to a standard with known concentration.

TL;DR: An experimental system for measuring the rate of protein transport in an inert, macroporous membrane is presented and it is demonstrated that the measured transport rates are consistent with diffusion of protein in a complex, interconnected network of water-filled pores.

TL;DR: The present experiments demonstrate that temperature, glycerol, sucrose, and various alcohol-water mixtures strongly influence the kinetics of photobleaching and recovery, and conclude that the change in conformation of the protein induced by light exposes a hydrophobic site to the solvent.

TL;DR: The whole-cell recording mode of the patch-clamp technique was used to study the effect of external tetraethylammonium ([TEA+]o) on the inactivating, voltage-dependent K+ channels of human T lymphocytes, resulting in a crossover of the current records in the presence and absence of TEA+.

TL;DR: The micrographs suggest that the same intermediate structure mediates both membrane fusion and III phase formation in phospholipids, as previously suggested.

TL;DR: A method has been developed, based on global analysis of both donor and acceptor fluorescence decay curves, which overcomes this extreme cross-correlation and allows the parameters of the equilibrium distance distributions and intramolecular diffusion constants to be recovered with high statistical significance and accuracy.

TL;DR: It is suggested that both mechanical and thermal changes in the nerve fibers are associated with the release and re-binding of Ca-ions in the nerves associated with action potential production.

TL;DR: The experimental observation that platelet aggregation occurred predominantly in the spaces between adjacent thrombi, confirmed the numerical prediction that those standing vortices are regions of reduced fluid velocities and high concentrations of platelet-activating substances, capable of trapping and stimulating platelets for aggregation.

TL;DR: It is shown that phase tracking can accurately locate the phase of the capacitance signal and can keep the detector aligned with this signal during measurements of exocytosis in mast cells, irrespective of the large drifts which occur in cell membrane resistance, membrane capacitance, or series resistance.

TL;DR: It is shown that the characteristic double-peaked specific heat, with a narrow and a broad component, is a natural consequence of the topology of the phase diagram.

TL;DR: Melittin spin-labeled specifically with a nitroxide at positions 7, 21, 23, or the amino terminus was bound to phospholipid membranes, and the exposure of the spin label to the aqueous phase was investigated by measurement of Heisenberg exchange with chromium oxalate in the solution.

TL;DR: The induced dipoles of the membrane and the protein contributes with approximately 10 kcal/mol to the solvation energy inside the channel and can therefore not be discarded in a realistic description of ion solvation in the Gramicidin channel.

TL;DR: Rat olfactory receptor neurons were enzymatically dissociated and studied with the cell-attached configuration of the patch-clamp technique and membrane electrical properties were found to be consistent with those of salamander cells investigated by others using whole-cell recording.

TL;DR: The phase transitions in fully hydrated dipalmitoylphosphatidylcholine (DPPC) and DPPC/water/ethanol phases have been studied by lowangle time-resolved x-ray diffraction under conditions similar to those employed in calorimetry to propose a "sequential" relaxation mechanism for the subgel-gel transition.

TL;DR: This work confirms and extends the milling crowd model of Eisinger, J., J. Flores, and W. P. Petersen and defines a distance-dependent, concentration-dependent diffusion coefficient, which is evaluated by Monte Carlo calculations of a random walk by mobile point tracers in the presence of immobile obstacles on a triangular lattice.

TL;DR: A quantitative explanation of the electrical activity observed in pancreatic islets is developed, which includes both ATP-sensitive and Ca2+-activated potassium conductances, which reproduces the experimentally observed electrical activity and may correspond more closely to the actual situation in vivo.