abstract：:Evidence from electron microscopy indicates that the separation between adjacent membranes of the central nervous system (CNS) is less than 500 A and perhaps as small as 100-250 A. The rapid K(+) efflux associated with the neural action potential may therefore be sufficient to affect the local extracellular potassium ...

journal_title：Biophysical journal

authors： Lebovitz RM

更新日期：1970-05-01 00:00:00

abstract：:The elastic properties of cylindrical segments of sarcolemma were studied in single striated fibers of the frog semitendinosus muscle. All measurements were made on membranes of retraction zones, cell segments from which the sarcoplasm had retracted. Quantitative morphological studies indicated that three deforming fo...

journal_title：Biophysical journal

authors： Fields RW

更新日期：1970-05-01 00:00:00

abstract：:Bases, nucleosides, nucleotides, and polynucleotides were exposed to chemically generated singlet oxygen to determine whether the species oxidized paralleled those oxidized in photodynamic reactions. In neutral or basic aqueous solution guanine, guanosine, deoxyguanosine, guanylic acid, deoxyguanylic acid, thymine, an...

journal_title：Biophysical journal

authors： Hallett FR,Hallett BP,Snipes W

更新日期：1970-04-01 00:00:00

abstract：:In order to verify the "radiation protection" effect of prosthetic groups in irradiated conjugated proteins and the influence of their electronic structure on intramolecular excitation transfer, two series of substances were examined. The first was composed of ferrihemoglobin and its constituents and the second was co...

journal_title：Biophysical journal

authors： Crippa PR,Vecli A

更新日期：1970-03-01 00:00:00

abstract：:A phenomenological theory for contracting muscle based on irreversible thermodynamics and the sliding filament theory is developed. The individual cross bridges, considered as subunits, are viewed as linear energy converters with constant transport coefficients. With this view of the subunits, phenomenological equatio...

journal_title：Biophysical journal

authors： Bornhorst WJ,Minardi JE

更新日期：1970-02-01 00:00:00

abstract：:Density-gradient centrifugation of disintegrated cells from a variety of plants gave two kinds of chlorophyll particles from all except the blue-green algae. As in previous procedures using detergents, the lighter Fraction 1 particles usually had greater absorption at longer wavelengths; they always had a lower ratio ...

journal_title：Biophysical journal

authors： Brown JS

更新日期：1969-12-01 00:00:00

abstract：:Numerous discussions of the relationship of the thermodynamics of radiation to photosynthesis have been published, but the results are often in disagreement or at best difficult to compare with one another. The recent treatment of maximal photosynthetic efficiencies by Ross and Calvin is here shown to be directly rela...

journal_title：Biophysical journal

authors： Knox RS

更新日期：1969-11-01 00:00:00

abstract：:The classical cable equation, in which membrane conductance is considered constant, is modified by including the linearized effect of membrane potential on sodium and potassium ionic currents, as formulated in the Hodgkin-Huxley equations for the squid giant axon. The resulting partial differential equation is solved ...

journal_title：Biophysical journal

authors： Sabah NH,Leibovic KN

更新日期：1969-10-01 00:00:00

abstract：:We have studied the combined effects of X-irradiation and nitrogen mustard treatment on the colony-forming ability of Chinese hamster cells. In contrast to X-irradiation, nitrogen mustard acting by itself yields an exponential dose-effect relationship. Moreover, whether delivered in immediate sequence or after varying...

journal_title：Biophysical journal

authors： Sakamoto K,Elkind MM

更新日期：1969-09-01 00:00:00

abstract：:Fiber orientation and ventricular geometry are incorporated in a mathematical model for ejection fraction of the human left ventricle. The inadequacy of circularly oriented or "constrictor" fibers to explain high ejection fractions of cylindrical, spherical, or ellipsoidal reference ventricles is demonstrated. A class...

journal_title：Biophysical journal

authors： Sallin EA

更新日期：1969-07-01 00:00:00

abstract：:Diluted bull semen samples were bombarded with a 24 Mev proton beam. Dose response curves for the fraction of cells which survived the bombardment and for the average velocity of the surviving cells were measured. Target theory indicated a cross section of the sensitive volume of 2.1 x 10(-10) cm(2). Respiration measu...

journal_title：Biophysical journal

authors： Rikmenspoel R,van Herpen G

更新日期：1969-06-01 00:00:00

abstract：:The electric quadrupole moment of the deuterium nucleus provides a nuclear magnetic resonance (NMR) probe of electric field gradients, and thereby of organization of tissue water. 8-17% of H(2)O in rat muscle and brain was replaced by D(2)O from 50% deuterated drinking water. The peak height of the steady-state NMR sp...

journal_title：Biophysical journal

authors： Cope FW

更新日期：1969-03-01 00:00:00

abstract：:The use of one-dimensional electron density strip models in interpreting low-angle X-ray data from planar and concentric multilayered structures is described. Diffraction formulas for an n-strip model are given. Fourier transforms, normalization constants, and Patterson functions are derived for certain strip models. ...

journal_title：Biophysical journal

authors： Worthington CR

更新日期：1969-02-01 00:00:00

abstract：:It is shown that alpha-helical content of eleven proteins is well correlated with alanine plus leucine content. These residues, taken singly or together, are to a first approximation randomly distributed in the four proteins whose tertiary structures have been determined (i.e., myoglobin, lysozyme, ribonuclease, alpha...

journal_title：Biophysical journal

authors： Prothero JW

更新日期：1968-11-01 00:00:00

abstract：:A number of models proposed to account for the sodium conductance changes are shown to fall into two classes. The Hodgkin-Huxley (HH) model falls into a class (I) in which the conductance depends on two or more independent variables controlled by independent processes. The Mullins, Hoyt, and Goldman models fall into c...

journal_title：Biophysical journal

authors： Hoyt RC

更新日期：1968-10-01 00:00:00

abstract：:Coliphage T4 was used as a model system to study the mechanism of biological inactivation produced by tritium decay. Experimentally, tritiated precursors were incorporated into phage DNA (thymidine-(3)H) or into phage protein ((3)H-amino acids). The ratio of killing efficiencies for decays originating in phage DNA to ...

journal_title：Biophysical journal

authors： Funk F,Person S,Bockrath RC Jr

更新日期：1968-09-01 00:00:00

abstract：:Individual ion activities were calculated for Ca(2+) in pure solutions of CaCl(2) and in mixtures of CaCl(2) with MgCl(2) and with NaCl, using different conventions to obtain gamma(Ca2+). The results were compared with potentiometric measurements, using calcium specific electrodes. It is found that significant differe...

journal_title：Biophysical journal

authors： Shatkay A

更新日期：1968-08-01 00:00:00

abstract：:The arrangement of side chains in alpha-helical regions of protein can be represented by helical net-diagrams. The addition of quantitative indices of the character of the residue at each net-point facilitates a straightforward examination of the groupings of residues of different character. As such the method complem...

journal_title：Biophysical journal

authors： Dunnill P

更新日期：1968-07-01 00:00:00

abstract：:To give a realistic representation of the pulse propagation in arteries a theoretical analysis of the wave propagation through a viscous incompressible fluid contained in an initially stressed elastic tube is considered. The tube is assumed to be orthotropic and its longitudinal motion is constrained by a uniformly di...

journal_title：Biophysical journal

authors： Atabek HB

更新日期：1968-05-01 00:00:00

abstract：:Thymine dimers were irradiated in aqueous solution with (60)Co gamma-rays in N(2) or O(2). Thymine and unidentified non-UV-absorbing products appeared. The thymine was identified by spectrophotometry, chromatography, and ability to support the growth of Escherichia coli 15 T(-). Residual dimer was determined by a UV-r...

journal_title：Biophysical journal

authors： Deering RA,Snipes W

更新日期：1968-03-01 00:00:00

abstract：:THE THEORY OF ELECTROTONUS, WHICH HAS BEEN WELL DEVELOPED FOR SMALL CYLINDERS, IS EXTENDED: the fundamental potential equations for a membrane of arbitrary shape are derived, and solutions are found for cylindrical and spherical geometries. If two purely conductive media are separated by a resistance-capacitance membr...

journal_title：Biophysical journal

authors： Hellerstein D

更新日期：1968-03-01 00:00:00

abstract：:Mössbauer spectra of anhydrohemoglobin establish the existence of two ferrous iron spin states in anhydrohemoglobin. Magnetic susceptibility measurements show that anhydrohemoglobin is paramagnetic and has an effective magnetic moment per iron atom of 3.5+/-0.1mu(B) at low temperatures. In conjunction with the suscept...

journal_title：Biophysical journal

authors： Grant RW,Cape JA,Gonser U,Topol LE,Saltman P

更新日期：1967-11-01 00:00:00

abstract：:Measurements were made of exchange rates of oxygen, carbon dioxide, and krypton-85 with blood at 37.5 degrees C. Gas transfer took place across a 1 mil silicone rubber membrane. The blood was in a rotating disk boundary layer flow, and the controlling resistance to transfer was the concentration boundary layer. Measur...

journal_title：Biophysical journal

authors： Spaeth EE,Friedlander SK

更新日期：1967-11-01 00:00:00

abstract：:Small amounts of paramagnetic cations quench the phosphorescence of DNA. Although the emission intensity is monotonic with increasing thymine content, the quenching efficiency is not. The cations quench from phosphate sites. ...

journal_title：Biophysical journal

authors： Isenberg I,Rosenbluth R,Baird SL Jr

更新日期：1967-07-01 00:00:00

abstract：:A mathematical model is formulated for the development of a population of cells in which the individual members may grow and divide or die. A given cell is characterized by its age and volume, and these parameters are assumed to determine the rate of volume growth and the probability per unit time of division or death...

journal_title：Biophysical journal

authors： Bell GI,Anderson EC

更新日期：1967-07-01 00:00:00

abstract：:The molecular weight of single-stranded DNA from the slime mold Physarum polycephalum has been determined by alkaline gradient centrifugation. The average molecular weight during DNA synthesis ( approximately 1.5 x 10(7) D) is less than that observed in nonsynthetic periods ( approximately 4 x 10(7) D). On the basis o...

journal_title：Biophysical journal

authors： McGrath RA,Williams RW

更新日期：1967-05-01 00:00:00

abstract：:The availability of very high magnetic fields of up to 170,000 gauss made it worthwhile to pursue the search for a critical change in the rate of four enzyme substrate reactions. The four enzymes were ribonuclease, polyphenol oxidase, peroxidase, and aldolase. The experiments showed that, to within +/-3%, no detectabl...

journal_title：Biophysical journal

authors： Rabinovitch B,Maling JE,Weissbluth M

更新日期：1967-03-01 00:00:00

abstract：:Sinusoidal oscillatory flow of blood and of aqueous glycerol solutions was produced in rigid cylindrical tubes. For aqueous glycerol, the amplitude of the measured pressure gradient wave form conformed closely to that predicted by Womersley's theory of oscillatory flow, up to Reynolds numbers approaching 2000. Blood d...

journal_title：Biophysical journal

authors： Kunz AL,Coulter NA Jr

更新日期：1967-01-01 00:00:00

abstract：:Diffusion of the chloride salts of Li, Na, K, Rb, and Cs from water into 1-butanol and from 1-butanol into water was examined at temperatures from 13-40 degrees C. Distribution coefficients, interfacial transfer coefficients, Arrhenius activation energy, free energy of activation, enthalpy, and entropy of activation w...

journal_title：Biophysical journal

authors： Ting HP,Bertrand GL,Sears DF

更新日期：1966-11-01 00:00:00

abstract：:The effects of internally and externally applied sulfhydryl reagents on the bioelectric properties of the giant axon of the squid Loligo pealeii and Dosidicus gigas were studied. Cysteine-HCl (400 mM, pH 7.3) was used to remove axoplasm from the perfusion channel. Oxidizing agents (1 to 60 mM) tended to increase the d...

journal_title：Biophysical journal

authors： Huneeus-Cox F,Fernandez HL,Smith BH

更新日期：1966-09-01 00:00:00

abstract：:One of the disadvantages of the sucrose-gap method for measuring membrane potentials with extracellular electrodes is a membrane hyperpolarization of the order of 30 to 60 mv, as compared with the resting potential obtained with intracellular microelectrodes in the absence of a sucrose-gap. In the present study the co...

journal_title：Biophysical journal

authors： Blaustein MP,Goldman DE

更新日期：1966-07-01 00:00:00

abstract：:In an attempt to quantitate the physical behavior of biological systems, Fourier analysis has been applied to the respiratory and circulatory systems by a number of investigators. The validity of this application has been questioned on the basis that these systems are nonlinear and not strictly periodic. If these obje...

journal_title：Biophysical journal

authors： Attinger EO,Anné A,McDonald DA

更新日期：1966-05-01 00:00:00

abstract：:Proliferation of mammalian cells, even under conditions of unlimited growth, presents a complex problem because of the interaction of deterministic and stochastic processes. Division of the cell cycle into a finite number of parts establishes a multidimensional vector space. In this space an arbitrary culture can be r...

journal_title：Biophysical journal

authors： Hahn GM

更新日期：1966-05-01 00:00:00

abstract：:A model for the action of vinblastine (VLB) on cells multiplying exponentially in vivo with a generation time, T(G), has been derived. It is based on the assumption that cells attempting to pass through mitosis in the presence of VLB lose their proliferative capacity and that this lethal effect occurs only when the ce...

journal_title：Biophysical journal

authors： Valeriote FA,Bruce WR,Meeker BE

更新日期：1966-03-01 00:00:00

abstract：:Trains of nerve impulses from the crayfish stretch receptor under steady conditions are found to be extremely regular with a standard deviation of S = 0.7 x 10(-2)tau when tau, the mean interval, is in the 15 to 80 msec range. Such a small fluctuation increases the problems of film recording, accurate measurement of i...

journal_title：Biophysical journal

authors： Firth DR

更新日期：1966-03-01 00:00:00

abstract：:Equations are derived describing the dispersion of a permeable solute during Poiseuille flow in a capillary model. It is shown that for the normal range of physiological parameters such as capillary radius, capillary length, blood flow, permeability coefficients, and diffusion constants, the center of mass of a bolus ...

journal_title：Biophysical journal

authors： Pollock F,Blum JJ

更新日期：1966-01-01 00:00:00

abstract：:A kinetic analysis of membrane conductance under conditions of stationary flow is presented. The semipermeable membrane is idealized as a homogeneous laminar phase separating ionic solutions on either side. It is assumed, without consideration of the mechanisms involved, that some ion species permeate the membrane whi...

journal_title：Biophysical journal

authors： Bruner LJ

更新日期：1965-11-01 00:00:00

abstract：:The mathematical model of steady-state iron kinetics in the human presented here extends the use of radioactive tracer observations in the determination of erythron maturative and proliferative behavior. Functions descriptive of that behavior appear explicitly in the model together with functions customarily measured ...

journal_title：Biophysical journal

authors： Nooney GC

更新日期：1965-11-01 00:00:00

abstract：:The human brain may be regarded as an irreversible system which is constrained by a fixed inflow of free energy in the form of chemical nourishment from within the body and information from the environment. The evolution of the internal spontaneous process may be described as a path on the saddle surface of entropy pr...

journal_title：Biophysical journal

authors： Kirkaldy JS

更新日期：1965-11-01 00:00:00

abstract：:When a dissolved macromolecule is in chemical equilibrium with a free ionic species, the charge configuration, and hence the dipole vector, of the macromolecule is fluctuating. Expressions for the static dielectric constant and the relaxation spectrum of such a mixture are here derived in terms of the components of th...

journal_title：Biophysical journal

authors： Scheider W

更新日期：1965-09-01 00:00:00