Abstract:
:The relationship between epithelial fluid transport, standing osmotic gradients, and standing hydrostatic pressure gradients has been investigated using a perturbation expansion of the governing equations. The assumptions used in the expansion are: (a) the volume of lateral intercellular space per unit volume of epithelium is small; (b) the membrane osmotic permeability is much larger than the solute permeability. We find that the rate of fluid reabsorption is set by the rate of active solute transport across lateral membranes. The fluid that crosses the lateral membranes and enters the intercellular cleft is driven longitudinally by small gradients in hydrostatic pressure. The small hydrostatic pressure in the intercellular space is capable of causing significant transmembrane fluid movement, however, the transmembrane effect is countered by the presence of a small standing osmotic gradient. Longitudinal hydrostatic and osmotic gradients balance such that their combined effect on transmembrane fluid flow is zero, whereas longitudinal flow is driven by the hydrostatic gradient. Because of this balance, standing gradients within intercellular clefts are effectively uncoupled from the rate of fluid reabsorption, which is driven by small, localized osmotic gradients within the cells. Water enters the cells across apical membranes and leaves across the lateral intercellular membranes. Fluid that enters the intercellular clefts can, in principle, exit either the basal end or be secreted from the apical end through tight junctions. Fluid flow through tight junctions is shown to depend on a dimensionless parameter, which scales the resistance to solute flow of the entire cleft relative to that of the junction. Estimates of the value of this parameter suggest that an electrically leaky epithelium may be effectively a tight epithelium in regard to fluid flow.
journal_name
Biophys Jjournal_title
Biophysical journalauthors
Mathias RTdoi
10.1016/S0006-3495(85)83986-2subject
Has Abstractpub_date
1985-06-01 00:00:00pages
823-36issue
6eissn
0006-3495issn
1542-0086pii
S0006-3495(85)83986-2journal_volume
47pub_type
杂志文章abstract::Gene regulation involves a hierarchy of events that extend from specific protein-DNA interactions to the combinatorial assembly of nucleoprotein complexes. The effects of DNA sequence on these processes have typically been studied based either on its quantitative connection with single-domain binding free energies or ...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/j.bpj.2010.08.006
更新日期:2010-10-20 00:00:00
abstract::An analysis is presented of the complex anisotropy behavior of trans-parinaric acid in single component DEPC lipid bilayers. It is shown that a model involving two species with distinct lifetime and motional behavior is required, and is adequate, to explain the observed data. In particular, the observed increase in th...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/S0006-3495(89)82909-1
更新日期:1989-06-01 00:00:00
abstract::Equations describing the movement of sugars during induced uphill transport were derived on the assumption of a simple carrier transport mechanism and subjected to experimental verification. Since there was good agreement between the experimental points and the theoretical curves, no changes in the original postulates...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/S0006-3495(65)86726-1
更新日期:1965-07-01 00:00:00
abstract::Single molecule force spectroscopy methods, such as optical and magnetic tweezers and atomic force microscopy, have opened up the possibility to study biological processes regulated by force, dynamics of structural conformations of proteins and nucleic acids, and load-dependent kinetics of molecular interactions. Amon...
journal_title:Biophysical journal
pub_type: 杂志文章,评审
doi:10.1016/j.bpj.2013.08.007
更新日期:2013-09-17 00:00:00
abstract::Fission fragment tracks from uranium-stained biological preparations have been observed in the electron microscope in a study of the feasibility of their use as tracers. Virus, DNA, and tissue sections were stained with uranium, prepared for electron microscopy, irradiated in the high thermal neutron flux of a nuclear...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/s0006-3495(64)86765-5
更新日期:1964-01-01 00:00:00
abstract::The fundamental backbone dynamics of unfolded proteins arising due to intrinsic ϕ-ψ dihedral angle fluctuations dictate the course of protein folding, binding, assembly, and function. These internal fluctuations are also critical for protein misfolding associated with a range of human diseases. However, direct observa...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/j.bpj.2016.07.023
更新日期:2016-08-23 00:00:00
abstract::The Green's function technique is applied to a study of breathing modes in a DNA double helix which contains a region of different base pairs from the rest of the double helix. The calculation is performed on a G-C helix in the B conformation with four consecutive base pairs replaced by A-T. The average stretch in hyd...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/S0006-3495(90)82570-4
更新日期:1990-03-01 00:00:00
abstract::To determine the effect of hydration on the dynamics of a protein complex, we used deuterium nuclear magnetic resonance (NMR) techniques to examine a trimethoprim (TMP)/E. coli dihydrofolate reductase (DHFR) complex in its lyophilized, partially hydrated, polycrystalline, and ammonium sulfate-precipitated states. The ...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/S0006-3495(93)81486-3
更新日期:1993-04-01 00:00:00
abstract::The relative contributions of the allosteric and affinity factors toward the change in p50 have been calculated for a series of effectors of hemoglobin (Hb). Shifts in the ligand affinity of deoxy Hb and the values for 50% ligand saturation (p50) were obtained from oxygen equilibrium data. Because the high-affinity pa...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/S0006-3495(90)82556-X
更新日期:1990-03-01 00:00:00
abstract::In the rabbit corneal stroma, the swelling pressure, P, has been reported to have an anomalous (negative) temperature coefficient, alpha P, contradicting traditional Donnan swelling theory. A parallel-plate, diffuse double layer Gouy-Chapman model was used to resolve this discrepancy. The present model incorporates th...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/S0006-3495(90)82584-4
更新日期:1990-03-01 00:00:00
abstract::The aquaglyceroporin GlpF is a transmembrane channel of Escherichia coli that facilitates the uptake of glycerol by the cell. Its high glycerol uptake rate is crucial for the cell to survive in very low glycerol concentrations. Although GlpF allows both influx and outflux of glycerol, its structure, similar to the str...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/S0006-3495(03)74718-3
更新日期:2003-11-01 00:00:00
abstract::The molecular basis of the activation of G-proteins by the G-protein coupled receptor for parathyroid hormone (PTH) is unknown. Employing a combination of NMR methods and computer-based structural refinement, structural features involved in the activation of Galpha(s) by the PTH receptor (PTH1R) have been determined. ...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1529/biophysj.106.094813
更新日期:2007-01-15 00:00:00
abstract::Bacterial swimming speed is sometimes known to increase with viscosity. This phenomenon is peculiar to bacterial motion. Berg and Turner (Nature. 278:349-351, 1979) indicated that the phenomenon was caused by a loose, quasi-rigid network formed by polymer molecules that were added to increase viscosity. We mathematica...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/S0006-3495(02)75204-1
更新日期:2002-08-01 00:00:00
abstract::The influence of mass transport on ligand binding to receptor immobilized in a polymer matrix, as detected with an evanescent wave biosensor, was investigated. A one-dimensional computer model for the mass transport of ligand between the bulk solution and the polymer gel and within the gel was employed, and the influe...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/S0006-3495(96)79681-9
更新日期:1996-03-01 00:00:00
abstract::Proteins are not rigid molecules, but exhibit internal motions on timescales ranging from femto- to milliseconds and beyond. In solution, proteins also experience global translational and rotational motions, sometimes on timescales comparable to those of the internal fluctuations. The possibility that internal and glo...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/j.bpj.2011.05.041
更新日期:2011-07-06 00:00:00
abstract::Calmodulin (CaM) is a highly flexible calcium-binding protein that mediates signal transduction through an ability to differentially bind to highly variable binding sequences in target proteins. To identify how binding affects CaM motions, and its relationship to conformational entropy and target peptide sequence, we ...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/j.bpj.2012.08.037
更新日期:2012-10-03 00:00:00
abstract::We present here an efficient and accurate procedure for modeling of the three-dimensional structures of polypeptides in the explicit solvent water based on molecular dynamics calculations. Using the toxic domain analog of heat-stable enterotoxin as a model peptide, we examined the utilities of two molecular dynamics t...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/S0006-3495(94)80975-0
更新日期:1994-06-01 00:00:00
abstract::It has been a long belief that release of substances from the cell to the extracellular milieu by exocytosis is completed by diffusion of the substances from secretory vesicles through the fusion pore. Involvement of any mechanical force that may be superposed on the diffusion to enhance the releasing process has not ...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/S0006-3495(02)75159-X
更新日期:2002-07-01 00:00:00
abstract::We have studied the large increase in macroscopic potassium channel current caused by catecholamines in mammalian cardiac cells. An increase in macroscopic K current could result from either an increase in the single-channel current or by an increase in the number of channels that are open. Therefore, we have measured...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/S0006-3495(89)82872-3
更新日期:1989-04-01 00:00:00
abstract::A method for life cycle analysis in mammalian cells which utilizes the collection function has been applied to the Chinese hamster ovary grown in suspension. The following durations were found for the various parts of the life cycle: S, 4.13 hours; G1, 4.71 hours; G2, 2.81 hours; mitosis, 0.81 hours. The cell has a to...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/s0006-3495(64)86794-1
更新日期:1964-11-01 00:00:00
abstract::Emerging evidence indicates that mitochondrial flashes (mitoflashes) are highly conserved elemental mitochondrial signaling events. However, which signal controls their ignition and how they are integrated with other mitochondrial signals and functions remain elusive. In this study, we aimed to further delineate the s...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/j.bpj.2016.05.052
更新日期:2016-07-26 00:00:00
abstract::Intracellular cargo transport frequently involves multiple motor types, either having opposite directionality or having the same directionality but different speeds. Although significant progress has been made in characterizing kinesin motors at the single-molecule level, predicting their ensemble behavior is challeng...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/j.bpj.2014.09.009
更新日期:2014-10-21 00:00:00
abstract::The electrophoretic behavior of defined DNA and RNA oligonucleotide duplexes from 10 to 20 bp in length has been investigated as a function of salt conditions, gel concentration, and temperature. The RNA oligomers migrated much more slowly than the DNA oligomers of the same sequence under all conditions. From sediment...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/S0006-3495(97)78185-2
更新日期:1997-09-01 00:00:00
abstract::Glasses used to fabricate patch pipettes may release components which affect ion channels (Cota, G., and C.M. Armstrong. 1988. Biophys. J. 53:107-109; Furman, R.E., and J.C. Tanaka. 1988. Biophys. J. 53:287-292; Rojas, L., and C. Zuazaga. 1988. Neurosci. Lett. 88:39-44). The gating properties of maxi K+ channels from ...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/S0006-3495(91)82127-0
更新日期:1991-10-01 00:00:00
abstract::The proline-, glutamate-, valine-, and lysine-rich (PEVK) domain of the giant muscle protein titin is thought to be an intrinsically unstructured random-coil segment. Various observations suggest, however, that the domain may not be completely devoid of internal interactions and structural features. To test the validi...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/j.bpj.2012.08.042
更新日期:2012-10-03 00:00:00
abstract::A lattice relaxation algorithm is developed to solve the Poisson-Nernst-Planck (PNP) equations for ion transport through arbitrary three-dimensional volumes. Calculations of systems characterized by simple parallel plate and cylindrical pore geometries are presented in order to calibrate the accuracy of the method. A ...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/S0006-3495(99)77232-2
更新日期:1999-02-01 00:00:00
abstract::Muscle contraction occurs as the result of actin-myosin interaction, which is mediated by the intermolecular forces exerted at the actin-myosin interface. To obtain information about the nature of these intermolecular forces, we tested the sensitivity of various contractile parameters of skinned skeletal muscle fibers...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/S0006-3495(00)76850-0
更新日期:2000-06-01 00:00:00
abstract::Chromatin is partitioned on multiple length scales into subcompartments that differ from each other with respect to their molecular composition and biological function. It is a key question how these compartments can form even though diffusion constantly mixes the nuclear interior and rapidly balances concentration gr...
journal_title:Biophysical journal
pub_type: 杂志文章,评审
doi:10.1016/j.bpj.2018.03.011
更新日期:2018-05-22 00:00:00
abstract::We investigated self-adhesion between highly negatively charged aggrecan macromolecules extracted from bovine cartilage extracellular matrix by performing atomic force microscopy (AFM) imaging and single-molecule force spectroscopy (SMFS) in saline solutions. By controlling the density of aggrecan molecules on both th...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/j.bpj.2010.09.002
更新日期:2010-11-17 00:00:00
abstract::Motions through the energy landscape of proteins lead to biological function. At temperatures below a dynamical transition (150-250 K), some of these motions are arrested and the activity of some proteins ceases. Here, we introduce the technique of temperature-derivative fluorescence microspectrophotometry to investig...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/S0006-3495(04)74365-9
更新日期:2004-05-01 00:00:00