Abstract：
:The theory of the electromagnetic blood flow measuring technique is extended from the well known case (conductive liquid flowing through an insulating tube) to more realistic situations. First the conductivity of the vessel is taken into account, and the electric potentials in both liquid and vessel wall are calculated. The potential difference V between two points on the outside of the vessel and on an axis at right angles to both magnetic field B and the flow v is computed. The comparison is made with the classical flowmeter result V = 2Ba[UNK] (a = inner radius of vessel, [UNK] = mean flow velocity). For an average artery, with a ratio of inside diameter to outside diameter of 0.85, the error is found to be in the order of -7 per cent. The blood is assumed to be four times as conductive as the wall tissue. The induced potentials are then calculated in the liquid, in the vessel wall, and in a thin liquid conductive layer surrounding the artery. A film of serous fluid which is likely to exist between a blood vessel and the applied flowmeter sleeve creates an additional shunt. The voltage between the flowmeter electrodes deviates from the expected result by -10 to -15 per cent if the film thickness is 3 per cent of the outside radius of the tube. The evidence is therefore established that flowmeter cuffs should fit the blood vessels accurately to minimize errors.
journal_name
Biophys Jjournal_title
Biophysical journalauthors
GESSNER Udoi
10.1016/s0006-3495(61)86912-9subject
Has Abstractpub_date
1961-11-01 00:00:00pages
627-37eissn
0006-3495issn
1542-0086pii
S0006-3495(61)86912-9journal_volume
1pub_type
杂志文章abstract：:A structural model is suggested for axon membranes consisting of a double layer of lipid and phospholipid molecules in which the polar ends of certain phospholipids change their orientation and combining properties under the influence of an electric field. The phosphate groups act as ion exchange "gates" for the contr...
journal_title：Biophysical journal
pub_type： 杂志文章
doi：10.1016/s0006-3495(64)86776-x
更新日期：1964-05-01 00:00:00
abstract：:We explore the means by which immobilization of a substrate on a surface can increase the rate of a diffusion-controlled enzymatic reaction. A quasichemical approach is developed and compared with Brownian dynamics simulations. We use these methods to show that restricting only the orientation of the enzyme by long-ra...
journal_title：Biophysical journal
pub_type： 杂志文章
doi：10.1529/biophysj.105.072785
更新日期：2006-02-01 00:00:00
abstract：:Photosystem II contains two well-characterized tyrosine radicals, D(.) and Z(.). Z is an electron carrier between the primary chlorophyll donor and the manganese catalytic site and is essential for enzymatic function. On the other hand, D forms a stable radical with no known role in oxygen evolution. D(.) and Z(.) giv...
journal_title：Biophysical journal
pub_type： 杂志文章
doi：10.1016/S0006-3495(96)79394-3
更新日期：1996-10-01 00:00:00
abstract：:An algorithm needed for computer simulation of immunodiffusion has been deduced from existing theories of the in vitro reaction between antibody and antigen. The "Goldberg most probable polymer distribution" theory provides a formula that gives the amount of free antibody, free antigen, and diffusible complexes from e...
journal_title：Biophysical journal
pub_type： 杂志文章
doi：10.1016/S0006-3495(73)85996-X
更新日期：1973-05-01 00:00:00
abstract：:The calcium release channels/ryanodine receptors (RyRs) usually form two-dimensional regular lattices in the endoplasmic/sarcoplasmic reticulum membranes. However, the function and modulation of the interaction between neighboring RyRs are still unknown. Here, with an in vitro aqueous system, we demonstrate that the i...
journal_title：Biophysical journal
pub_type： 杂志文章
doi：10.1529/biophysj.105.065409
更新日期：2005-09-01 00:00:00
abstract：:The kinetic properties of the three taxonomic A substates of sperm whale carbonmonoxy myoglobin in 75% glycerol/buffer are studied by flash photolysis with monitoring in the infrared stretch bands of bound CO at nu(A0) approximately 1967 cm-1, nu(A1) approximately 1947 cm-1, and nu(A3) approximately 1929 cm-1 between ...
journal_title：Biophysical journal
pub_type： 杂志文章
doi：10.1016/S0006-3495(96)79359-1
更新日期：1996-09-01 00:00:00
abstract：:We modeled two different mechanisms, a shunting conductance and a slow sodium inactivation, to test whether they could modulate the active propagation of a train of action potentials in a dendritic tree. Computer simulations, using a compartmental model of a pyramidal neuron, suggest that each of these two mechanisms ...
journal_title：Biophysical journal
pub_type： 杂志文章
doi：10.1016/S0006-3495(96)79433-X
更新日期：1996-11-01 00:00:00
abstract：:A new form of metabolic flux analysis (MFA) called thermodynamics-based metabolic flux analysis (TMFA) is introduced with the capability of generating thermodynamically feasible flux and metabolite activity profiles on a genome scale. TMFA involves the use of a set of linear thermodynamic constraints in addition to th...
journal_title：Biophysical journal
pub_type： 杂志文章
doi：10.1529/biophysj.106.093138
更新日期：2007-03-01 00:00:00
abstract：:Calmodulin (CaM) is an intracellular cooperative calcium-binding protein essential for activating many diverse target proteins. Biophysical studies of the calcium-induced conformational changes of CaM disagree on the structure of the linker between domains and possible orientations of the domains. Molecular dynamics s...
journal_title：Biophysical journal
pub_type： 杂志文章
doi：10.1016/S0006-3495(96)79535-8
更新日期：1996-12-01 00:00:00
abstract：:Exceptions to the Meyer-Overton rule are commonly cited as evidence against indirect, membrane-mediated mechanisms of general anesthesia. However, another interpretation is possible within the context of an indirect mechanism in which solubilization of an anesthetic in the membrane causes a redistribution of lateral p...
journal_title：Biophysical journal
pub_type： 杂志文章
doi：10.1016/S0006-3495(01)76200-5
更新日期：2001-05-01 00:00:00
abstract：:A new method of fluorescence microscopy for cell imaging has been developed that takes advantage of the spatial variations of fluorescence lifetimes in single cells as a source of image contrast, and thus it is named "fluorescence lifetime imaging microscopy (flimscopy)". Since time-resolved fluorescence measurements ...
journal_title：Biophysical journal
pub_type： 杂志文章
doi：10.1016/S0006-3495(93)81427-9
更新日期：1993-03-01 00:00:00
abstract：:Fluorescent probes in biological systems are sensitive to environmental polarity by virtue of their response to the reaction field created by polarization of the dielectric medium. Classically, fluorophore solvatochromism is analyzed in terms of the Lippert equation and later variants, all of which rely upon the origi...
journal_title：Biophysical journal
pub_type： 杂志文章
doi：10.1016/j.bpj.2009.01.006
更新日期：2009-04-08 00:00:00
abstract：:The crystal structure of the RNA octamer, 5'-GGCGUGCC-3' has been determined from x-ray diffraction data to 1.5 angstroms resolution. In the crystal, this oligonucleotide forms five self-complementary double-helices in the asymmetric unit. Tandem 5'GU/3'UG basepairs comprise an internal loop in the middle of each dupl...
journal_title：Biophysical journal
pub_type： 杂志文章
doi：10.1529/biophysj.106.081018
更新日期：2006-06-15 00:00:00
abstract：:The ability to discriminate between different cations efficiently is essential for the proper physiological functioning of many membrane transport proteins. One obvious mechanism of ion selectivity is when a binding site is structurally constrained by the protein architecture and its geometry is precisely adapted to f...
journal_title：Biophysical journal
pub_type： 杂志文章
doi：10.1016/j.bpj.2010.03.038
更新日期：2010-06-16 00:00:00
abstract：:We report that voltage-gated Na+ channels (Na(V)) from rat muscle (mu1) expressed in HEK293 cells exhibit anomalous rectification of whole-cell outward current under conditions of symmetrical Na+. This behavior gradually fades with time after membrane break-in, as if a diffusible blocking substance in the cytoplasm is...
journal_title：Biophysical journal
pub_type： 杂志文章
doi：10.1016/S0006-3495(01)76102-4
更新日期：2001-03-01 00:00:00
abstract：:The conformation of mononucleosome complexes reconstituted with recombinant core histones on a 614-basepair-long DNA fragment containing the Xenopus borealis 5S rRNA nucleosome positioning sequence was studied by scanning/atomic force microscopy in the absence or presence of linker histone H1. Imaging without prior fi...
journal_title：Biophysical journal
pub_type： 杂志文章
doi：10.1016/S0006-3495(03)74815-2
更新日期：2003-12-01 00:00:00
abstract：:We present in this report a detailed structural study of calf gamma-crystallins both in the solid state and in solution by the newly developed technique of near-infrared (IR) Fourier transform (FT)-Raman spectroscopy as well as by the conventional Raman method. In comparison with conventional laser Raman spectroscopy,...
journal_title：Biophysical journal
pub_type： 杂志文章
doi：10.1016/S0006-3495(91)82071-9
更新日期：1991-08-01 00:00:00
abstract：:In rat mesenteric arteries, smooth muscle cells exhibit intercellular calcium waves in response to local phenylephrine stimulation. These waves have a velocity of approximately 20 cells/s and a range of approximately 80 cells. We analyze these waves in a theoretical model of a population of coupled smooth muscle cells...
journal_title：Biophysical journal
pub_type： 杂志文章
doi：10.1016/j.bpj.2010.04.031
更新日期：2010-07-21 00:00:00
abstract：:The steady-state stimulus-response curve of the Limulus ventral photoreceptor comprises a linear portion followed by a less-than-unity power law dependence, which is maintained over at least 4 decades of intensity. This progressive desensitization corresponds to light adaptation. For flash stimulation of dark-adapted ...
journal_title：Biophysical journal
pub_type： 杂志文章
doi：10.1016/S0006-3495(88)83111-4
更新日期：1988-03-01 00:00:00
abstract：:Flagellin is the subunit of the bacterial filament, the micrometer-long propeller of a bacterial flagellum. The protein is believed to undergo unfolding for transport through the channel of the filament and to refold in a chamber at the end of the channel before being assembled into the growing filament. We report a t...
journal_title：Biophysical journal
pub_type： 杂志文章
doi：10.1529/biophysj.107.123927
更新日期：2008-05-15 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：:Förster resonance energy transfer (FRET)-based biosensors for the quantitative analysis of intracellular signaling, including sensors for monitoring cyclic adenosine monophosphate (cAMP), are of increasing interest. The measurement of the donor/acceptor emission ratio in tandem biosensors excited at the donor excitati...
journal_title：Biophysical journal
pub_type： 杂志文章
doi：10.1529/biophysj.107.125666
更新日期：2008-12-01 00:00:00
abstract：:Atrial fibrosis has been implicated in the development and maintenance of atrial arrhythmias, and is characterized by expansion of the extracellular matrix and an increased number of fibroblasts (Fbs). Electrotonic coupling between atrial myocytes and Fbs may contribute to the formation of an arrhythmogenic substrate....
journal_title：Biophysical journal
pub_type： 杂志文章
doi：10.1016/j.bpj.2009.07.054
更新日期：2009-10-21 00:00:00
abstract：:In adherent and motile neutrophils NAD(P)H concentration, flavoprotein redox potential, and production of reactive oxygen species and nitric oxide, are all periodic and exhibit defined phase relationships to an underlying metabolic oscillation of approximately 20 s. Utilizing fluorescence microscopy, we have shown in ...
journal_title：Biophysical journal
pub_type： 杂志文章
doi：10.1529/biophysj.104.056663
更新日期：2005-05-01 00:00:00
abstract：:Fluorescence fluctuation spectroscopy has become an important measurement tool for investigating molecular dynamics, molecular interactions, and chemical kinetics in biological systems. Although the basic theory of fluctuation spectroscopy is well established, it is not widely recognized that saturation of the fluores...
journal_title：Biophysical journal
pub_type： 杂志文章
doi：10.1529/biophysj.104.052779
更新日期：2005-09-01 00:00:00
abstract：:Conventional equations for enzyme kinetics are based on mass-action laws, that may fail in low-dimensional and disordered media such as biological membranes. We present Monte Carlo simulations of an isolated Michaelis-Menten enzyme reaction on two-dimensional lattices with varying obstacle densities, as models of biol...
journal_title：Biophysical journal
pub_type： 杂志文章
doi：10.1016/S0006-3495(02)73953-2
更新日期：2002-10-01 00:00:00
abstract：:Very high dielectric constants have been observed for bacteria at low frequencies. High dielectric constants such as these can be explained by a theory which has been developed for the low-frequency dielectric dispersion of porous charged particles and which has been tested successfully through measurements with ion e...
journal_title：Biophysical journal
pub_type： 杂志文章
doi：10.1016/S0006-3495(73)85966-1
更新日期：1973-01-01 00:00:00
abstract：:The influence of the amino acid residues surrounding the flavin ring in the flavodoxin of the cyanobacterium Anabaena PCC 7119 on the electron spin density distribution of the flavin semiquinone was examined in mutants of the key residues Trp(57) and Tyr(94) at the FMN binding site. Neutral semiquinone radicals of the...
journal_title：Biophysical journal
pub_type： 杂志文章
doi：10.1016/S0006-3495(99)77017-7
更新日期：1999-09-01 00:00:00
abstract：:The motor head of kinesin carries out microtubule binding, ATP hydrolysis, and force generation. Despite a high level of sequence and structural conservation, subtle variations in subdomains of the motor head determine family-specific properties. In particular, both Kinesin-1 (Kin-1) and Kinesin-5 (Kin-5) walk process...
journal_title：Biophysical journal
pub_type： 杂志文章
doi：10.1016/j.bpj.2013.03.051
更新日期：2013-05-07 00:00:00
abstract：:We examined the state-, voltage-, and time dependences of interaction between 4-AP and a mammalian A-type K channel clone (rKv1.4) expressed in Xenopus oocytes using whole-cell and single-channel recordings. 4-AP blocked rKv1.4 from the cytoplasmic side of the membrane. The development of block required channel openin...
journal_title：Biophysical journal
pub_type： 杂志文章
doi：10.1016/S0006-3495(94)80462-X
更新日期：1994-07-01 00:00:00
