bluuebunny/crossref_metadata_2025_split huggingface dataset:
ELECTROKINETIC MEMBRANE PROCESSES IN RELATION TO PROPERTIES OF EXCITABLE TISSUES
Authors: Teorell Torsten 
Published: May 2004

A quantitative theory is presented for the behavior of a membrane-electrolyte system subject to an electric current flow (the "membrane oscillator"). If the membrane is porous, carries "fixed charges," and separates electrolyte solutions of different conductances, it can be the site of repetitive oscillatory changes in the membrane potential, the membrane resistance, and the hydrostatic pressure difference across the membrane. These events are accompanied by a pulsating transport of bulk solutions. The theory assumes the superposition of electrochemical and hydrostatic gradients and centers round the kinetics of resistance changes within the membrane, as caused by effects from diffusion and electro-osmotic fluid streaming. The results are laid down in a set of five simple, basic expressions, which can be transformed into a pair of non-linear differential equations yielding oscillatory solutions. A graphical integration method is also outlined (Appendix II).
The agreement between the theory and previous experimental observations is satisfactory. The applied electrokinetic concepts may have importance in relation to analyses of the behavior of living excitable cells or tissues.
RESPONSES OF MOTONEURONS UNDERGOING CHROMATOLYSIS
Authors: McIntyre A. K. , Bradley K. , Brock L. G. 
Published: May 2004

The delayed and asynchronous firing of chromatolytic motoneurons in response to group I afferent volleys is shown to be evoked monosynaptically, there being an abnormally long and variable delay between onset of monosynaptic action and generation of impulse discharge. Intensity of monosynaptic excitatory action is reduced, and considerable variability in the form of successively evoked postsynaptic potentials is often observed. No evidence has been found for the development of excitatory group I polysynaptic pathways.
Reduction in responsiveness of finer dendrites is indicated by the feeble "d" response evoked by an antidromic volley in a chromatolytic motor nucleus. Antidromic impulses appear to invade the cell bodies and coarse dendrites, but die out at points short of the normal extent of dendritic invasion. Vigorous firing of Renshaw cells can be elicited by antidromic volleys.
Chromatolytic motoneurons appear to maintain reasonably normal resting membrane potentials, but are more susceptible to damage than are normal cells. Action potentials are large and usually overshoot the resting potential level. Post spike potentials are similar to those of normal cells except for a less prominent, or absent, early phase of depolarisation.
In contrast with the reduced responsiveness of peripheral dendrites, there is a lowered threshold for antidromic and segmental reflex synaptic activation of the more central regions, probably the cell bodies and nearby coarse dendrites, of motoneurons undergoing chromatolysis.
The Effect of the Ovarian Steroids on the Membrane Potential of Uterine Muscle
Authors: Goto M. , Csapo A. 
Published: May 2004

Measurements with flexible intracellular microelectrodes show that the rabbit myometrium when insufficiently stimulated by estrogen has a low membrane potential of about 30 to 35 mv. Estrogen (endogenous or exogenous) increases this value up to 43 to 48 mv., whereas progesterone increases it still further up to 55 to 60 mv.
Between the 20th and 29th days of rabbit pregnancy the membrane potential at placental implantation sites is about 10 mv. higher than between these sites. Progesterone treatment increases the value at the interplacental sites to the level of the placental sites. The onset of labor is preceded by a drop in membrane potential at the placental sites to the level of the interplacental sites. This change results in a more or less uniform potential of 45–50 mv. along the length of the uterine horn at term.
The membrane potential of the uterus is a log function of the [K]0 at values greater than 12 mM/liter, as is the case in other excitable tissues. In Ca-free Krebs the membrane potential of the estrogen-dominated uterus drops to a low level; the progesterone-dominated myometrium exhibits only a transient and lesser decrease.
The membrane potential of the myometrial cell is influenced by endocrine regulation. The correlation between membrane potential and threshold only holds for the estrogen-dominated uterus, however, in other endocrine conditions the relationship breaks down.
The Electrophoretic Velocity of Human Red Cells, of Their Ghosts and Mechanically Produced Fragments, and of Certain Lipid Complexes
Authors: Ponder Eric , Ponder Ruth V. 
Published: May 2004

Ghosts prepared in CO2-saturated water from unwashed human red cells can be fragmented mechanically, but ghosts from thrice washed cells cannot. If the ghosts are prepared by freezing and thawing, this difference is not observed.
The electrophoretic velocity varies also with the way in which the ghosts are prepared. The pH-mobility dependence of washed red cells flatten off to a plateau at pH 9, and the electrophoretic velocity is zero at about pH 2. Ghosts prepared by freezing and thawing have almost the same pH-mobility dependence, but if the ghosts are prepared in CO2-saturated hyptonic saline, the mobility at pH 9.4 is 0.75 times that of washed cells. Fragments of ghosts of unwashed red cells have a smaller mobility than that of the red cells. Trypsin reduces the mobility of washed red cells and of ghosts.
Sols of lipid complexes (lecithin, cephalin, and lipositol), at varying pH's, have a mobility 1.2 times that of the washed red cell. The pH-mobility relation is otherwise similar. These complexes can be coated with dextran and trypsin.
Studies of the Origin of Bacterial Viruses
Authors: Northrop John H. ,   with the technical assistance of Marie King
Published: May 2004

Exposure of B. megatherium 899 to about 5 x 10-3 M MnCl2 for 10 minutes at 25°C. results in an increase of about ten times in the proportion of phage-producing cells, terramycin-resistant cells, streptomycin-resistant cells, and phage-resistant cells.
The proportion of phage-producing cells reaches a maximum in about 4 hours and that of the other cells is reached in about 8 hours.
The Nature of the Retinal Action Potential, and the Spectral Sensitivities of Ultraviolet and Green Receptor Systems of the Compound Eye of the Worker Honeybee
Authors: Goldsmith Timothy H. 
Published: May 2004

1. The retinal action potential consists principally of a sustained negative wave which persists for as long as the stimulus. Transitory negative on-effects and off-effects may also be present, particularly at long wave lengths (green, yellow, and red) and in the light-adapted eye.
2. Only the maintained component of the potential can be elicited under CO2 anesthesia. The transient components are reversibly eliminated from the response at about the same time as the background noise of nerve and muscle spikes. It is suggested that the sustained component arises from the receptor cells, and the other components from second and higher order neurons.
3. The compound eye does not contain a homogeneous population of receptors. A green receptor system (maximum sensitivity at about 535 mµ) determines the response of the dark-adapted eye throughout most of the spectrum; during adaptation to yellow light, however, an ultraviolet receptor system is revealed, with maximum sensitivity at about 345 mµ. The anatomical bases of these receptor systems are unknown; however, they include both retinula cells and neurons in the optic ganglion.
4. There is no change in spectral sensitivity (Purkinje shift) in the first three logarithmic units above the threshold of the retinal action potential.
5. The relatively great effectiveness of near ultraviolet light in stimulating the positive phototaxis of the bee does not depend on excitation of the ultraviolet receptor of the ocellus.
Non-Linear Current-Potential Relations in an Axon Membrane
Authors: Cole Kenneth S. 
Published: May 2004

The membrane current density, Im, in the squid giant axon has been calculated from the measured external current applied to the axon, Io, by the equation
See PDF for Equation
where Vm is the membrane potential under the current electrode and r1 and r2 are the external and internal longitudinal resistances. The original derivation of this equation included in one step an assumption of a linear relation between Im and Vm. It is shown that the same equation can be obtained without this restricting assumption.
Determination of the Effective Hydrodynamic Radii of Small Molecules by Viscometry
Authors: Schultz Stanley G. , Solomon A. K. 
Published: May 2004

The effective hydrodynamic radii of small uncharged molecules in dilute aqueous solution were determined using Einstein's classical theory of viscosity. The radii thus obtained are those of a hypothetical sphere whose hydrodynamic behavior is the same as that of the solute molecule plus that water of hydration which is too firmly bound to partake in the viscous shearing process. The results obtained compare favorably with radii determined from molecular models constructed in accordance with atomic dimensions compiled by Pauling. Although the application of the Einstein theory to molecules whose size is comparable to that of water represents a considerable extrapolation, the results suggest that this deviation from the assumptions of the theory, in the case of the molecules studied, is of second order importance.
Employing the viscometric radii, we have formulated an empirical correction of the Stokes-Einstein diffusion equation. This correction is similar in form to those previously proposed by Cunningham (22) and Millikan (21) and is of particular significance when the solute molecule is comparable in size to the discontinuities of the surrounding medium. The molecular radii of a number of small organic molecules obtained by means of the corrected Stokes-Einstein equation do not differ significantly from the radii obtained from molecular models of these compounds.
THE VISIBILITY OF MONOCHROMATIC RADIATION AND THE ABSORPTION SPECTRUM OF VISUAL PURPLE
Authors: Hecht Selig , Williams Robert E. 
Published: May 2004

1. After a consideration of the existing data and of the sources of error involved, an arrangement of apparatus, free from these errors, is described for measuring the relative energy necessary in different portions of the spectrum in order to produce a colorless sensation in the eye.
2. Following certain reasoning, it is shown that the reciprocal of this relative energy at any wave-length is proportional to the absorption coefficient of a sensitive substance in the eye. The absorption spectrum of this substance is then mapped out.
3. The curve representing the visibility of the spectrum at very low intensities has exactly the same shape as that for the visibility at high intensities involving color vision. The only difference between them is their position in the spectrum, that at high intensities being 48 µµ farther toward the red.
4. The possibility is considered that the sensitive substances responsible for the two visibility curves are identical, and reasons are developed for the failure to demonstrate optically the presence of a colored substance in the cones. The shift of the high intensity visibility curve toward the red is explained in terms of Kundt's rule for the progressive shift of the absorption maximum of a substance in solvents of increasing refractive index and density.
5. Assuming Kundt's rule, it is deduced that the absorption spectrum of visual purple as measured directly in water solution should not coincide with its position in the rods, because of the greater density and refractive index of the rods. It is then shown that, measured by the position of the visibility curve at low intensities, this shift toward the red actually occurs, and is about 7 or 8 µµ in extent. Examination of the older data consistently confirms this difference of position between the curves representing visibility at low intensities and those representing the absorption spectrum of visual purple in water solution.
6. It is therefore held as a possible hypothesis, capable of direct, experimental verification, that the same substance—visual purple—whose absorption maximum in water solution is at 503 µµ, is dissolved in the rods where its absorption maximum is at 511 µµ, and in the cones where its maximum is at 554 µµ (or at 540 µµ, if macular absorption is taken into account, as indeed it must be).
THE INFLUENCE OF ELECTROLYTES ON THE CATAPHORETIC CHARGE OF COLLOIDAL PARTICLES AND THE STABILITY OF THEIR SUSPENSIONS
Authors: Loeb Jacques 
Published: May 2004

1. When collodion particles suspended in water move in an electric field they are, as a rule, negatively charged. The maximal cataphoretic P.D. between collodion particles and water is about 70 millivolts. This is only slightly more than the cataphoretic P.D. found by McTaggart to exist between gas bubbles and water (55 millivolts). Since in the latter case the P.D. is entirely due to forces inherent in the water itself, resulting possibly in an excess of OH ions in the layer of water in contact and moving with the gas bubble, it is assumed that the negative charge of the collodion particles is also chiefly due to the same cause; the collodion particles being apparently only responsible for the slight difference in maximal P.D. of water-gas and water-collodion surfaces.
2. The cataphoretic charge of collodion particles seems to be a minimum in pure water, increasing as a rule with the addition of electrolytes, especially if the cation of the electrolyte is monovalent, until a maximal P.D. is reached. A further increase in the concentration of the electrolyte depresses the P.D. again. There is little difference in the action of HCl, NaOH, and NaCl or LiCl or KCl.
3. The increase in P.D. between collodion particles and water upon the addition of electrolyte is the more rapid the higher the valency of the anion. This suggests that this increase of negative charge of the collodion particle is due to the anions of the electrolyte gathering in excess in the layer of water nearest to the collodion particles, while the adjoining aqueous layer has an excess of cations.
4. In the case of chlorides and at a pH of about 5.0 the maximal P.D. between collodion particles and water is about 70 millivolts, when the cation of the electrolyte present is monovalent (H, Li, Na, K); when the cation of the electrolyte is bivalent (Mg, Ca), the maximal P.D. is about 35 to 40 millivolts; and when the cation is trivalent (La) the maximal P.D. is lower, probably little more than 20 millivolts.
5. A reversal in the sign of charge of the collodion particles could be brought about by LaCl3 but not by acid.
6. These results on the influence of electrolytes on the cataphoretic P.D. between collodion particles and water are also of significance for the theory of electrical endosmose and anomalous osmosis through collodion membranes; since the cataphoretic P.D. is probably identical with the P.D. between water and collodion inside the pores of a collodion membrane through which the water diffuses.
7. The cataphoretic P.D. between collodion particles and water determines the stability of suspensions of collodion particles in water, since rapid precipitation occurs when this P.D. falls below a critical value of about 16 millivolts, regardless of the nature of the electrolyte by which the P.D. is depressed. No peptization effect of plurivalent anions was noticed.
THE COLLOIDAL BEHAVIOR OF SERUM GLOBULIN
Authors: Hitchcock David I. 
Published: May 2004

1. The globulin prepared from ox serum by dilution and precipitation with carbon dioxide has been found, by electrometric titration experiments, to behave like an amphoteric electrolyte, reacting stoichiometrically with acids and bases.
2. The potential difference developed between a solution of globulin chloride, phosphate, or acetate and a solution of the corresponding acid, free from protein, separated from the globulin by a collodion membrane, was found to be influenced by hydrogen ion concentration and salt concentration in the way predicted by Donnan's theory of membrane equilibrium. In experiments with sodium globulinate and sodium hydroxide it was found that the potential difference could be similarly explained.
3. The osmotic pressure of such solutions could be qualitatively accounted for by the Donnan theory, but exhibited a discrepancy which is explicable by analogy with certain experiments of Loeb on gelatin.
4. The application of Loeb's theory of colloidal behavior, which had previously been found to hold in the case of gelatin, casein, egg albumin, and edestin, has thus been extended to another protein, serum globulin.
THE EXCRETION OF CARBON DIOXIDE BY RELAXED AND CONTRACTED SEA ANEMONES
Authors: Parker G. H. 
Published: May 2004

1. The metabolism of the sea anemone Metridium marginatum Edw. was measured in four states, relaxed, relaxing, contracted, and contracting, by means of an Osterhout respiratory apparatus. The basis of measurement was the number of hundred-thousandths of a milligram of carbon dioxide excreted per second by a gram of living sea anemone.
2. In the relaxed state this varied from 6.1 to 4.4+ and averaged 5.43–.
3. In a comparison of the relaxed and contracted states the amount of carbon dioxide excreted was found to beabout the same; in one instance in relaxation 4.2 and in contraction 4.1+; in another in relaxation 7.8+ and 7.9– and in contraction 8.1–.
4. In a comparison of the three states relaxed, relaxing, and contracting, the first two were found to average about the same, 4.8+ and 4.6– respectively and the last proved to be appreciably higher 7.1–.
5. It is, therefore, concluded that the process of relaxing and the states of relaxation and of contraction are accompanied by no unusual metabolism, but that in the operation of contracting the metabolism becomes about half again as intense as that characteristic of the other states.
6. The maintenance of the contracted state in Metridium for days at a time without an increase of metabolism indicates that its musculature is of the type known as tonus muscle.
7. In tonus muscle, contraction is accomplished by an active shortening of the myofibrils, extension by a passive drawing out of these fibrils through the distension of the adjacent cavities, etc., and the continued maintenance of any particular state of shortening by some form of catch mechanism in the muscle, such, possibly, as the gelation of its sarcoplasm.
THE STABILITY OF BACTERIAL SUSPENSIONS
Authors: De Kruif Paul H. , Northrop John H. 
Published: May 2004

1. The amount of immune body required to agglutinate a suspension of Bacillus typhosus increases in direct proportion to the concentration of the suspension.
2. The amount of immune body combined with the organisms is constant from pH 9 to pH 3.7. Below the latter value the amount in combination is decreased.
3. The addition of immune serum to a suspension of Bacillus typhosus at a pH of 2,5 increases the positive charge of the organisms.
These results are contradictory to the idea that the combination is caused by a difference in the sign of the charge carried by the immune body and the organism. They agree with the assumption that the immune body forms a film on the surface of the organism and that the effect on the charge is the result of this film.
THE ADHESIVENESS OF LEUCOCYTES TO SOLID SURFACES
Authors: Fenn Wallace O. 
Published: May 2004

1. Methods are described for measuring the stickiness of cells to solid surfaces.
2. The effect of various factors such as temperature, serum concentration, sodium chloride concentration, etc., on the adhesiveness of leucocytes to solid surfaces and the phagocytosis of solid particles are compared, and certain marked differences pointed out.
3. On account of these differences it is concluded that forces of surface tension, though undoubtedly operative in determining the behavior of cells in contact with solid bodies, are not the only factors involved.
4. Ways in which changes in the structure or rigidity of the protoplasm might affect phagocytosis and adhesiveness in opposite directions are suggested.
EFFECT OF THE HYDROGEN ION CONCENTRATION ON THE PHAGOCYTOSIS AND ADHESIVENESS OF LEUCOCYTES
Authors: Fenn Wallace O. 
Published: May 2004

1. Immediately after coming into contact with glass, leucocytes are most adhesive at pH 8.0 or &gt; 8.0.
2. Agglutination of leucocytes increases with increasing H ion concentration from pH 8.0 to 6.0.
3. In phagocytosis experiments where leucocytes creep about on the slide picking up articles the optimum pH is 7.0. Here ameboid movement is probably the limiting factor.
4. The optimum for phagocytosis of quartz from suspension is on the acid side of neutrality at or near pH 6.7.
5. Phagocytosis of quartz increases with the acidity, while adhesiveness of leucocytes to glass increases with the alkalinity.
THE INFLUENCE OF AMMONIUM SALTS ON CELL REACTION
Authors: Jacobs M. H. 
Published: May 2004

1. It may be shown by means of cells of the flowers of a hybrid Rhododendron which contain a natural indicator, by means of starfish eggs stained with neutral red, and by means of an "artificial cell" in which living frog's skin is employed that increased intracellular alkalinity may be brought about by solutions of a decidedly acid reaction which contain ammonium salts.
2. These results are analogous to those previously obtained with the CO2-bicarbonate system, and depend on the facts: (a) that NH4OH is sufficiently weak as a base to permit a certain degree of hydrolysis of its salts; and (b) that living cells are freely permeable to NH4OH (or NH3?) and not to mineral and many organic acids, and presumably not at least to the same extent to ammonium salts as such.
A MICRO INJECTION STUDY ON THE PERMEABILITY OF THE STARFISH EGG
Authors: Chambers Robert 
Published: May 2004

The experiments with the NH4Cl are similar to, and corroborate micro injection experiments performed in connection with some work on mustard gas in which the writer collaborated. Eggs immersed in sea water containing decomposed mustard gas, at a certain low concentration are not affected. If, however, the solution be injected, the egg quickly cytolyzes owing to the free HCl present.
A similar impermeability of the protoplasmic surface film to certain substances was also encountered in injection work on Amœba. Amœbœ immersed in an aqueous solution of eosin will not take the stain till after death. On the other hand, the eosin, when injected into the Amœba, quickly permeates the protoplasm, to be arrested only at the surface.
The semipermeability of a living cell appears primarily to be a function of its surface film. It is immaterial whether this film be that of the original cortex of the cell, a film newly formed over a cut surface, or a film that surrounds an artificially induced vacuole within the cell. As long as such a surface film exists neither the acid group of the NH4Cl nor the alkaline group of the NaHCO3 can, within certain concentration limits, penetrate the protoplasm. These solutions, if injected beneath the surface film, however, will produce their characteristic effects upon the protoplasm.
THE PERMEABILITY OF LIVING CELLS TO DYES AS AFFECTED BY HYDROGEN ION CONCENTRATION
Authors: Irwin Marian 
Published: May 2004

1. An accurate quantitative method of measuring the penetration of dye into the living cell is described.
2. Cresyl blue is unable to penetrate rapidly unless the pH outside the cell is decidedly greater than that inside. The rate of penetration increases with increasing pH.
3. Around pH 9 penetration of the dye is rapid while the reverse is true of exosmosis. At low pH values (5.9) exosmosis is rapid and penetration is very slow.