bluuebunny/crossref_metadata_2025_split huggingface dataset:
BLUE LIGHT AND THE REGENERATION OF HUMAN RHODOPSIN IN SITU
Authors: Rushton W. A. H. 
Published: May 2004

Hubbard has found that the photoisomerization of retinene was important for the regeneration of rhodopsin in vitro, and the object of the present investigation was to find whether this was also true for regeneration in the living human eye.
In the Appendix is described a device which permits the rhodopsin density to be measured by analysing the light reflected from the fundus oculi in an ophthalmoscopic arrangement, the measurement taking about 5 seconds. Now if a blue and a yellow light viewed scotopically are adjusted in intensity so as to appear identical, they must bleach rhodopsin equally, but the blue will be more than 10 times as effective in isomerizing retinene. Therefore if retinene isomerization is important for rhodopsin regeneration, blue light should cause a more rapid regeneration after bleaching, and during bleaching the equilibrium level attained should be less profound. But, as the figures show, the course of bleaching and regeneration is identical for the matched yellow or blue bleaching lights, therefore isomerization of retinene is not important for rhodopsin regeneration in the living human eye.
TRANSMISSION IN SQUID GIANT SYNAPSES
Authors: Bryant S. H. 
Published: May 2004

Synaptic transmission was studied in giant synapses of the stellate ganglion of the squid. When bathed in air-saturated sea water, the synapses deteriorate in 10 to 20 min.; if the sea water is saturated with 100 per cent oxygen, they function steadily for up to 12 hours. Optimal results probably require a medium with lower magnesium and higher calcium than the sea water used.
Of eighteen compounds known to affect other synapses (Table I), none had stimulatory effects when applied to the preparation, but ten produced synaptic depression in concentrations of 10–3 gm. per ml. or higher. The only exception was procaine, which blocked at 6 x 10–5 gm. per ml.
Intracellular recording with microelectrodes near the synapse showed that the block was associated with a slower rise of the excitatory post-synaptic potential, without a change in the depolarization required to initiate the spike. Procaine was exceptional in also increasing the depolarization at which the spike occurred.
THE PROPERTIES AND THE ENZYMATIC DEGRADATION OF DESOXYRIBONUCLEOPROTEIN FROM LIVER CELL NUCLEI
Authors: Monty Kenneth J. , Dounce Alexander L. 
Published: May 2004

The isolation and properties of a desoxyribonucleoprotein of the rat liver cell nucleus are described. This material consists of DNA (desoxyribonucleic acid) bound to the residual chromosomal protein by what appear to be covalent linkages. Lipide is present, but can be removed by extraction in lipide solvents prior to isolation of the nucleoprotein, without much change in the physical properties of the latter. The nucleoprotein in question forms elastic, recoilable gels in molar saline at pH 7.0 or in water at pH 8.0 to 10.0 or even higher, which are similar to those that can be obtained from whole nuclei.
The effects of x-rays, heat, and enzymes on the nucleoprotein are discussed, and the composition of the protein component is investigated. The latter contains an "occult" protein that can be liberated by heating in 0.1 N HCl.
A study of the enzymatic degradation of the desoxyribonucleoprotein has been made, with the aim of attempting the isolation of small polynucleotide fragments attached to amino acids or short peptides that might be useful in characterizing the mode of attachment of the desoxyribonucleic acid to the protein in the desoxyribonucleoprotein. Evidence is presented indicating that such products can be isolated through the use of electrophoresis on paper.
A STATISTICAL ANALYZER FOR OPTIC NERVE MESSAGES
Authors: Fitzhugh Richard 
Published: May 2004

A statistical mathematical model of the discharge in a single optic nerve fiber is proposed, based on a discharge with intervals between impulses distributed independently according to a gamma distribution ("gamma discharge"). A light stimulus distorts the time axis of this discharge according to a "frequency function" which is characteristic of the stimulus.
A linear filter is described which calculates the likelihood of a certain stimulus when the nerve fiber message is fed into it. This filter forms the basis of theoretical nerve message analyzers for three visual experiments: (a) The detection of the occurrence of a flash of light of known intensity and time of occurrence, (b) the detection of the time of occurrence of a flash of known intensity, and (c) The estimation of the intensity of a flash occurring at a known time.
Possible neural mechanisms in the brain for analyzing optic nerve messages, based on the above mathematical models, are suggested. Changes of excitability or discharge frequency correspond to the output of the likelihood filter. Any such mechanism must be sufficiently plastic to have a response matched to each expected stimuus for most efficient vision near threshold.
THE RELATIONSHIP OF HYDROGEN PEROXIDE TO THE INHIBITION OF THE GLYOXALASE ACTIVITY OF INTACT ERYTHROCYTES BY X-RADIATION
Authors: Klebanoff S. J. 
Published: May 2004

The x-irradiation of a dilute suspension of erythrocytes results in a decrease in the glyoxalase activity of the cells as a result of a fall in the reduced glutathione level. The present paper deals with the possible role of H2O2 in this reaction.
The addition of intact erythrocytes to physiological saline previously irradiated with 150,000 r or 225,000 r results in a fall in the glyoxalase activity of the cells. The inhibition is prevented by the preincubation of the irradiated saline with catalase and is reversed by the addition of plasma, glucose, adenosine, and inosine to the cell suspension.
An inhibition of the glyoxalase activity is also produced by the addition of H2O2 to the suspension of erythrocytes. The inhibitory effect of H2O2 can be prevented and largely reversed by plasma, glucose, adenosine, and inosine. Methylglyoxal is also protective under these conditions.
Hydrogen peroxide formed continuously and in low concentrations by enzyme systems appears to be more effective than added H2O2 in inhibiting the glyoxalase system. The inhibition by H2O2-producing enzyme systems is minimized by the addition of catalase, plasma, glucose, methylglyoxal, and to a lesser extent, by adenosine and inosine, and is accentuated by the addition of sodium azide.
The results are discussed in relation to the role of H2O2 and catalase in the toxicity of ionizing radiations.
DISPOSITION OF INTRAPERITONEALLY INJECTED CALCIUM-45 IN SUCKLING RATS
Authors: Bronner Felix 
Published: May 2004

The time course of the concentration of radiocalcium was studied in the serum, skeleton, pelt, muscles, and pooled internal organs of 10-day-old rats. Within 10 hours of injection, the specific activity of the tissue groups exceeded the specific activity of the serum and remained above it during the period studied (120 hours).
Chemical and autoradiographic analyses showed how rapidly most of the injected Ca45 found its way into the skeleton. A model was constructed with the assumption that the skeleton constitutes an essentially irreversible reservoir for the tracer in a multicompartment system in which the blood is the central or feeding compartment.
The rate of transfer of the tracer from the soft tissue compartments to the serum was calculated from the equation
See PDF for Equation
in which C = concentration in serum (expressed as a series of exponential terms)
C' = concentration in a given soft tissue
Substitution in the integrated form of this equation yielded equations which had the major properties of the empirical equations fitted to the experimental points. The relative order of transfer constants (k'–1) was: organs ≥ pelt &gt; muscle.
ENDOGENOUS PHOTOSENSITIZATION IN A CAROTENOIDLESS MUTANT OF RHODOPSEUDOMONAS SPHEROIDES
Authors: Dworkin Martin 
Published: May 2004

Endogenous photosensitization in a carotenoidless mutant of Rhodopseudomonas spheroides has been studied.
When this mutant is exposed to visible light and oxygen there is a short lag period followed by exponential killing of the cells. The killing process obeys the Bunsen-Roscoe law of reciprocity and is temperature-independent.
The chlorophyll content of the cells does not affect the rate of killing until a certain low threshold has been reached.
Exposure of photosynthetically grown cells to air in the dark induces a temporary desensitization to the killing.
A certain proportion of the population is invariably resistant to the photokilling. Evidence is presented to show that the resistance of these cells is probably a result of their abnormally low chlorophyll content.
One consequence of the irradiation is the appearance of abnormally small colonies upon plating the survivors. This is interpreted in terms of a multi-hit theory.
The photosensitizing pigment itself (the intracellular bacteriochlorophyll) is destroyed. The process is zero order, temperature-dependent, and does not follow the reciprocity law.
It is suggested that the death of the cell results from a disruption of the cell membrane.
LIGHT-INDUCED EFFICIENCY AND PIGMENT ALTERATIONS IN RED ALGAE
Authors: Yocum C. S. , Blinks L. R. 
Published: May 2004

The low photosynthetic efficiency of chlorophyll in freshly collected red algae, can, in the case of Porphyra perforata, P. nereocystis, and Porphyridium cruentum, be increased by growing the algae for 10 days in red or blue light. Exposure to darkness or to green light maintains the algae in their originally low efficiency with respect to chlorophyll, while retaining the high efficiency of phycobilins. Red- or blue-adapted algae are rapidly reversed by exposure to green light, the chlorophyll efficiency dropping to low values again in a few hours. This is assumed to account for the action spectrum of freshly gathered plants.
Some pigment changes were observed, but not in the direction of "chromatic adaptation;" and the carotenoid pigments were not activated, even by blue light, but remained as photosynthetically inactive shading filters. The higher red algae (Florideae) did not show activation of chlorophyll by red or blue light.
THE CHARACTERIZATION AND LOCALIZATION OF FROG SKIN CHOLINESTERASE
Authors: Koblick Daniel C. 
Published: May 2004

Frog skin cholinesterase is largely of the serum (pseudocholinesterase) type. For whole skin, the activity at 10–1 AcChCl is 4.9 µl./mg. N/hr.
Tela subcutanea isolated by dissection exhibits an activity of 65 µl./mg. N/hr. at 10–1 AcChCl. Since about one-tenth of the nitrogen of the skin is located in the tela subcutanea, it is estimated that more than 90 per cent of the enzyme is associated with this tissue layer.
THE CALCULATION OF TRANSFER RATES IN TWO COMPARTMENT SYSTEMS NOT IN DYNAMIC EQUILIBRIUM
Authors: Berger Eugene Y. , Steele J. Murray 
Published: May 2004

Dynamic equilibrium in a biological system implies that the compartment under study does not change in size during the period of observation. In many biological systems there are, however, net changes with time and this report deals with the mathematical treatment necessary to calculate unequal rates of inflow and outflow.
A method is presented for the calculation of transfer rates in a two compartment system when the rates of flow between these compartments are unequal but constant. Equations were developed to calculate the amount of material transported per unit time derived from measurements of specific activity and compartment size.
The problems of (1) sampling from the pool and (2) the effects of analytical errors on the estimation of rate have been evaluated. An example has been presented in which the derived equations have been applied to a study of the simultaneous passage of sodium into and out of a permanently isolated loop of bowel.
THE FREEZING POINT DEPRESSION OF MAMMALIAN TISSUES AFTER SUDDEN HEATING IN BOILING DISTILLED WATER
Authors: Appelboom Johannes W. Th. , Brodsky William A. , Tuttle William S. , Diamond Israel 
Published: May 2004

The calculated freezing point depression of freshly excised boiled mammalian tissue is approximately the same as that of plasma. The boiling procedure was chosen to eliminate the influence of metabolism on the level of the freezing point depression. Problems created by the boiling, such as equilibrium between tissue and diluent, change in activity coefficient by dilution, and loss of CO2 content, are discussed.
A frozen crushed tissue homogenate is hypertonic to plasma. Boiling and dilution of such hypertonic homogenate exposed to room temperature for 5 to 15 minutes did not produce significant or unexplicable decreases in its osmotic activity. Moreover, freezing and crushing of a boiled diluted tissue did not produce any increase of the isoosmotic level of freezing point depression.
It is possible to explain these data either with the hypothesis of hypertonic cell fluid or with that of isotonic cell fluid. In the case of an assumed isotonic cell fluid, data can be explained with one assumption, experimentally backed. In the case of an assumed hypertonic theory data can be explained only with the help of at least three ad hoc postulates. The data support the validity of the classical concept which holds that cell fluid is isotonic to extracellular fluid.
THE SPECTRAL SENSITIVITIES OF THE DORSAL OCELLI OF COCKROACHES AND HONEYBEES
Authors: Goldsmith Timothy H. , Ruck Philip R. 
Published: May 2004

The spectral sensitivities of the dorsal ocelli of cockroaches (Periplaneta americana, Blaberus craniifer) and worker honeybees (Apis mellifera) have been measured by electrophysiological methods. The relative numbers of quanta necessary to produce a constant size electrical response in the ocellus were measured at various wave lengths between 302 and 623 mµ.
The wave form of the electrical response (ERG) of the dark-adapted roach ocellus depends on the intensity but not the wave length of the stimulating light. The roach ocellus appears to possess a single photoreceptor type, maximally sensitive about 500 mµ.
The ERG's of bee ocelli are qualitatively different in the ultraviolet and visible regions of the spectrum. The bee ocellus has two types of photoreceptor, maximally sensitive at 490 mµ and at about 335 to 340 mµ.
The spectral absorption of the ocellar cornea of Blaberus craniifer was measured. There is no significant absorption between 350 and 700 mµ.
STUDIES ON THE ORIGIN OF BACTERIAL VIRUSES
Authors: Northrop John H. ,   With the Technical Assistance of Marie King
Published: May 2004

I. The Incidence of Phage-Producing Cells in Various B. megatherium Cultures
Analyses of small samples containing a few cells each show that lysogenic B. megatherium produces phage particles in groups of from 10 to 1000 depending on the megatherium strain and the culture medium.
These groups probably correspond to the number of particles produced by a single cell. The proportion of such phage-producing cells varies from &lt;1 x 10-10 to about 1 x 10-2 depending on the megatherium strain and the culture medium.
If a culture produces two types of phage, the different types usually appear in separate samples. If mixed samples occur, the number of such samples is about what would be expected for the probability that two separate groups would appear in one sample. This result indicates that the appearance of a distinct phage type is the result of a change in the bacterial cell rather than a change in a phage particle, since in the latter case a mixture of the two types would result.
II. The Effect of Ultraviolet Light on the Incidence of Phage-Producing and of Terramycin-Resistant Cells in Various B. megatherium Cultures
Low intensity of ultraviolet light increases the proportion of both phage-producing cells and of terramycin-resistant mutants. The increase in phage-producing cells is greater than the increase in terramycin-resistant cells.
High intensities of ultraviolet light cause practically all the cells of some B. megatherium strains to produce phage. The number of terramycin-resistant mutants cannot be determined under these conditions.
The effect of ultraviolet light varies, depending on the megatherium strain and the culture medium.
III. The Effect of Hydrogen Peroxide on the Incidence of Phage-Producing and of Terramycin-Resistant Cells in Various B. megatherium Cultures
Low concentrations of hydrogen peroxide increase the number of phage-producing cells and of terramycin-resistant cells, concomitantly, from two to five times.
High concentrations of hydrogen peroxide cause almost all the cells of some strains of megatherium to produce phage.
IV. Calculation of the Incidence of Phage-Producing Cells
The time rate of the appearance of phage particles in normal cultures, or in cultures treated with ultraviolet light or hydrogen peroxide, may be calculated by the same equations which predict the occurrence of terramycin-resistant mutants in B. megatherium cultures.
These equations predict that the number of mutants will increase more or less in proportion to the concentration of mutagenic agent, so long as the mutation rate remains very small compared to the growth rate. As the mutation rate approaches the growth rate, there will be a very rapid increase in the proportion of mutants. This explains the striking effect of higher concentrations of mutagenic agents.
In order to calculate the results after exposure to strong ultraviolet light or hydrogen peroxide, it is necessary to assume that the change from normal to phage-producing cell occurs without cell division.
EFFECTS OF EXTERNAL CURRENTS ON DURATION AND AMPLITUDE OF NORMAL AND PROLONGED ACTION POTENTIALS FROM SINGLE NODES OF RANVIER
Authors: Mueller Paul 
Published: May 2004

Duration and amplitude of normal and prolonged action potentials from single nodes of Ranvier vary as functions of potential changes induced by currents from an external source. The quantitative relations between externally applied potential and the resulting potential generated within the system are analyzed in order to obtain information about the kinetics of the electromotance,—potential,—and chemical changes taking place during excitation. The following preliminary conclusions are drawn:
A depolarizing and a repolarizing process (positive and negative electromotance) increase and decrease with the potential. For a sudden potential displacement the negative electromotance reaches its new value at a faster rate than the positive electromotance. Since the individual values of the two electromotances depend on the potential and since they both generate a potential which is proportional to the difference of their absolute values, the values of either electromotance are determined by this difference as well as by any externally induced potential change.
ON THE KINETICS OF POTENTIAL, ELECTROMOTANCE, AND CHEMICAL CHANGE IN THE EXCITABLE SYSTEM OF NERVE
Authors: Mueller Paul 
Published: May 2004

The kinetics of interaction between potential, chemical equilibrium, and electromotance in the excitable system of nerve are analyzed. The theoretical system has the following properties:
It gives rise to two electromotances each of which depends directly on a chemical equilibrium. The equilibria are determined by the potential across the system.
After a sudden potential shift the equilibria reach their new value with an exponential time course, the time constant of which is determined by the rate constants of the two reactions. The rate constants are different due to different activation energies.
The two electromotances give rise to potentials of opposite sign. The total potential produced by the system is equal to the sum of the two potentials. The two equilibria are thus determined by any externally applied potential as well as by the sum of the internally produced potentials. The dependence of the equilibria on the potential is calculated from first principles.
The equations which describe this system are solved by an analogue computer, which gives instantaneous solutions of the total internal potential as a function of time and any voltage applied from an external source. Comparison between recorded and computed action potentials shows excellent agreement under all experimental conditions.
The electromotances might originate from a Ca++—Na+—K+ exchange at fixed negative sites in the Schwann cell.
THE EFFECTS OF AIR IONS ON THE LIVING MAMMALIAN TRACHEA
Authors: Krueger Albert P. , Smith Richard F. 
Published: May 2004

Studies on the effects of air ions on the functional efficiency of the extirpated tracheal strip have been extended to the trachea of the living rabbit, rat, and mouse. Animals exposed to high mobility (+) air ions administered via a tracheotomy aperture displayed: (a) Decreased ciliary activity. (b) Decline in mucus flow rate, sometimes reversed by prolonged exposure to (+) ions; a frequent drop in the volume of mucous secretion. (c) Contraction of the membranous posterior tracheal wall. (d) Increased vulnerability to trauma of cilia and mucosal blood vessels.
Similar treatment with (-) air ions reversed (+) ion effects on ciliary activity, mucus flow, contraction of the tracheal smooth muscle. Continued (-) ion treatment raised the ciliary rate (invariably) and the mucus flow rate (often) above their initial levels.
(+) Air ions administered to unoperated resting mice and rats increased the respiratory rate; (-) ions reversed this effect.
Long exposure of unoperated ambulatory mice to (+) air ions produced: (a) Decreased ciliary activity. (b) No clear cut effect on mucus flow. (c) Contraction of the posterior tracheal wall. (d) Increased vulnerability of the mucosa to trauma. (-) Air ions increased ciliary activity but had no clear-cut effect on the mucus flow rate.
PHYSIOLOGICAL CHARACTERISTICS OF HUMAN RED BLOOD CELL GHOSTS
Authors: Hoffman Joseph F. 
Published: May 2004

The properties of ghosts prepared by hypotonic hemolysis at various ratios of cells (C) to hemolyzing solution (H) have been studied. At all ratios, hemoglobin (Hb) was found to be distributed equally between the ghost and supernatant compartments. Techniques employing Fe59—labelled Hb showed that during hemolysis all of the Hb is exchangeable and that following hemolysis the ghost is impermeable to Hb.
Ghosts containing defined fractions of their original Hb were prepared by appropriately altering the ratio C/H. When washed and suspended in 0.17 M NaCl—PO4—buffered media, the ghosts returned to their initial volume, recovered normal shape, and behaved as osmometers. The rate of rehemolysis of these reconstituted ghosts was observed to be proportional to the concentration of Hb in the ghosts. The rate of rehemolysis was accelerated by the addition of n-butyl alcohol (BA). For a given concentration of BA, temperature, and Hb content the rate of rehemolysis was minimal around the isoelectric point of Hb. Rehemolysis by BA was inhibited by the addition of sucrose to the medium. K influx and outflux were measured and found to be increased by the addition of BA and not influenced by the presence of sucrose. These results on the rehemolytic characteristics of ghosts are consistent with and support the colloid-osmotic theory of hemolysis.
DELAYED LIGHT ACTION SPECTRA OF SEVERAL ALGAE IN VISIBLE AND ULTRAVIOLET LIGHT
Authors: McLeod G. C. 
Published: May 2004

Action spectra for delayed light production by several algae were determined from 250 to 750 mµ incident light.
In the visible portion of the spectrum the action spectra resemble those reported by previous workers for photosynthesis and light emission. Blue-green algae had a maximum at 620 mµ, red algae at 550 mµ, whereas green and brown algae have action spectra corresponding to chlorophyll and carotenoid absorption.
In the ultraviolet portion of the spectrum delayed light is emitted by algae down to 250 mµ incident light.
The action spectra of the different algae are not alike in the ultraviolet portion of the spectrum.
This indicates that pigments other than chlorophyll must be sensitizing or shielding the algae in the ultraviolet region.