bluuebunny/crossref_metadata_2025_split huggingface dataset:
OXIDATIVE PHOSPHORYLATION BY A CELL-FREE PARTICULATE SYSTEM FROM UNFERTILIZED ARBACIA EGGS
Authors: Keltch A. K. , Strittmatter C. F. , Walters C. P. , Clowes G. H. A. 
Published: May 2004

1. A cell-free particulate system capable of effecting oxidative phosphorylation has been prepared from unfertilized eggs of Arbacia punctulata.
A substantial increase in phosphorylation can be produced by addition of α-ketoglutarate, oxalacetate, or succinate, the magnitude of the increase being greatest with α-ketoglutarate.
The activity of the phosphorylating system is sharply dependent on maintenance of a comparatively narrow pH range during both the preparation of the particulate system and its subsequent incubation with oxidizable substrate.
2. The maximum oxygen consumption of the cell-free particulate system derived from a given weight of unfertilized eggs is about three times that of the same weight of intact unfertilized eggs and approximately the same as that of an equal weight of fertilized eggs.
3. The data indicate that generation of high-energy phosphate bonds in the Arbacia egg is coupled, as it is in mammalian liver or kidney, with the functioning of the tricarboxylic acid cycle.
AN ANALYSIS OF THE RELATIONSHIP BETWEEN SOLUBILITY AND STIMULATING EFFECT IN TARSAL CHEMORECEPTION
Authors: Dethier V. G. , Chadwick L. E. 
Published: May 2004

The rejection thresholds of the blowfly Phormia regina Meigen for a selected series of substituted aliphatic hydrocarbons have been determined and an analysis made of the effect on stimulation of increasing the number of like substitutions from one to two, of the interaction of different types of substituent, and of the position of the substituent in the molecule.
The order of stimulating efficiency (reciprocal of rejection threshold) of the functional groups which have been studied is: Br &gt; Cl ? CH3 ? CHO &gt; C=O &gt; OH. There is a consistent decrease in stimulating effect following the introduction of a second hydroxyl group. The introduction of a second C=O has little effect. Introduction of a second halogen is generally followed by a decrease in threshold. Two different species of functional group, one of which tends to increase water solubility and the other to decrease it, tend to counter-balance each other.
A single oxygen-containing functional group on the end of the molecule or two of these groups which are terminal reduce the stimulating effect less than when one or more of such groups are subterminal or located elsewhere within the molecule. Branching of the carbon chain decreases effectiveness. Sulfur and oxygen linkages also decrease effectiveness. In general, the length of the free alkyl group largely determines the stimulating effectiveness. Its power is modified to varying degrees by the nature of the attached polar groups.
Of all chemical properties examined, solubility alone agrees consistently with the foregoing data. Threshold varies directly with the molar solubility of the compounds in water. The fact that the threshold values for individual compounds are frequently different from those which would be expected solely on the basis of the correlation between threshold and solubility in water suggests that other factors are also concerned in stimulation. These have not yet been identified.
FREE AMINO ACIDS AND NUCLEIC ACID CONTENT OF CELL NUCLEI ISOLATED BY A MODIFICATION OF BEHRENS' TECHNIQUE
Authors: Dounce Alexander L. , Tishkoff Garson H. , Barnett Shirley R. , Freer Richard M. 
Published: May 2004

1. Nuclei were prepared from frozen rat liver by a modification of the technique of Behrens, and were studied with regard to the content of free amino acids and nucleic acid.
2. Under rigorously controlled conditions, preparations of nuclei are obtained by the Behrens' method which form a gel in the presence of 5 or 10 per cent NaCl or of water plus a small amount of dilute alkali; whereas when conditions are less rigorously controlled, nuclei are obtained which form no such gel. The property of forming gels with alkali is probably characteristic of all cell nuclei which have not undergone autolysis.
3. Nuclei prepared by the Behrens' technique contain the enzymes arginase, catalase, and esterase in very appreciable concentrations.
4. The free amino acids of the isolated cell nuclei, as well as of other liver cell fractions, have been investigated using the technique of paper chromatography.
5. The chromatographic patterns of the free amino acids of whole cells, ground cytoplasm, and isolated cell nuclei were very similar or identical. A feature of interest in these chromatograms was the faintness or absence of the spots due to a number of the essential amino acids, as compared to the intensities of the spots due to glycine, alanine, and glutamic acid. Glutathione was present in the isolated nuclei as well as in the whole cells.
6. Chromatograms made from hydrolysates of nuclei showed high concentrations of the essential amino acids and were similar to chromatograms of hydrolysates of typical proteins.
RATE OF POTASSIUM EXCHANGE OF THE HUMAN ERYTHROCYTE
Authors: Raker John W. , Taylor Isaac M. , Weller John M. , Hastings A. Baird 
Published: May 2004

1. The exchange of potassium by the human erythrocyte has been studied in vitro using radioactive potassium.
2. An incubation technique which maintains erythrocytes in an essentially normal state for over 48 hours was employed.
3. Exchange of radioactive potassium between the red cells and the extracellular fluid was regular and progressive, the specific activities of the intra- and extracellular fluids reaching equal values. This indicates that all the erythrocyte potassium is exchangeable and is exchanging at the same rate.
4. From these data, it was calculated that at 37°C., 1.6 per cent of the erythrocyte potassium exchanges per hour, corresponding to an exchange of 1.5 mM of potassium per liter of red cells per hour. The time required for the exchange of 50 per cent of the red cell potassium is calculated to be 43 hours.
5. The temperature coefficient (Q10) of the potassium exchange rate is 2.2. This is the same as the temperature coefficient of the rate of utilization of glucose by the human erythrocyte.
6. Varying the percentage of red cells, plasma potassium concentration, initial glucose level, and pH between 7.0 and 7.7 had no effect on the potassium exchange rate.
ON THE VISIBILITY OF RADIATION AT THE HUMAN FOVEA
Authors: Crozier W. J. 
Published: May 2004

1. Seeing-frequency functions (ψ[S]) determined uniocularly for small (1.6'), brief images at the thoroughly dark-adapted human central fovea take the form of log-Gaussian integrals, for intensity or for exposure-time as the independent variable. They cannot be of Poisson type, since mean (τ') and standard deviation (σ) are quite independently modifiable.
2. The properties of τ', the abscissa of inflection in the log-Gaussian integrals, and of σ, are discussed in relation to customary determinations of spectral visibilities; agreements and certain necessary divergences are considered.
3. The values of σlogΔIlogΔI0, are distributed periodically, with 5 maxima in the range λ383 to λ712. Outside the fovea this is not the case. These maxima, and the intervening minima, are definitely correlated with "irregularities" in the values of τ' as function of λ, with data on color threshold intensities, with data on "saturation," and quite specifically with minima and maxima in the data of λ discrimination. They are unmistakably of analytical significance.
4. The interpretation of these properties is taken to require (consistent with the indications of other evidence) that under specified conditions the magnitude of σ is a measure of the "size" of the population of excitable elements of neural effect, in the range of 0 to 100 per cent response-frequency as a function of wave number. This means that under the procedure used there is detectable the spectral distribution of local, specific, photosensitization. The σ's refer to a property of the excitation process which is not affected by the action of irrelevant absorbers.
5. A preliminary test of this has been made by the use of mixed "monochromatic" lights. The total energy is empirically the significant quantity, although the separate effects of λ's are sharply exhibited.
6. The λ distribution of photosensitization indices, σlogΔIlogΔI0, is necessarily taken to have the nature of "action spectra." Careful search discloses, surprisingly enough, precise and apparently unique correspondence with the maxima and minima (and details of shape) required for the participation of: cytochrome-c reductase; the reduced forms of cytochromes-a and -c; and the often overlooked ferric-prophyrin bands of oxidized cytochrome-c.
7. For the central fovea, in which blood vessels are absent, and in which resistance to anoxia is at a maximum, the presence of an enzyme system of the sort here indicated is entirely reasonable. It is pointed out that a number of specific experiments can be based upon the general finding, whatever the causal mechanism for the sensitized λ regions may in the end prove to be. The data cannot be reconciled to the demands of existing color primary theories, although apparently quite accurately consistent with varied observational data.
THE INTERACTION BETWEEN THE SYNAPSES OF A SINGLE MOTOR FIBER
Authors: Wiersma C. A. G. , Turner R. S. 
Published: May 2004

It has been shown that stimulation of synapses of the giant motor fibers of the third roots of Cambarus clarkii can block transmission at other synapses located on the same fiber. Peripherally located synapses block most synapses which are more centrally located. The reverse is true in a small number of cases. Possible reasons for this difference are discussed.
It was further found that the two medial giant fibers in fresh, carefully dissected, preparations show a functional connection in the brain. It is probable that, under natural conditions, both medial giant fibers are always active at the same time.
METHYL GREEN
Authors: Kurnick N. B. , Foster Marilee 
Published: May 2004

1. Methyl green ("ethyl green") C. I. Number 685 was examined and found to behave identically with methyl green C. I. Number 684 (no longer available) in respect to molar extinction coefficient, effect of combination with polymerized DNA, failure to react with depolymerized DNA, and effect of pH.
2. The mass law permits the calculation of P/dye. This is found to be 13 P/dye. The same value is obtained when an excess of methyl green is caused to fade by adjusting the pH to 7.5.
3. The compound formed by methyl green with DNA has the same maximum absorption at 642.5 to 645 mµ in the pH range 3.5–7.8, whereas the free dye fades markedly above pH 5.0.
THE ACCELERATING ACTION OF ILLUMINATION IN RECOVERY OF ARBACIA EGGS FROM EXPOSURE TO ULTRAVIOLET RADIATION
Authors: Blum Harold F. , Loos Gordon M. , Robinson J. Courtland 
Published: May 2004

Light of wave lengths 0.30µ to 0.50µ, accelerates return of the cleavage rate of Arbacia eggs to normal, after delay by exposure to ultraviolet radiation (wave lengths 0.238µ to 0.31µ). Recovery is apparently complete. Wave lengths 0.30µ to 0.50µ have no effect on the cleavage rate of normal eggs, nor does such illumination previous to dosage with ultraviolet radiation influence subsequent recovery. Acceleration of recovery of the egg occurs before fertilization as well as after.
The effects of ultraviolet radiation and recovery therefrom are essentially the same in nucleated "white halves" as in the intact eggs.
This phenomenon in the Arbacia egg seems basically comparable to photoreactivation of bacteria and fungi.
CHANGES IN THE POTASSIUM CONTENT OF SEA URCHIN EGGS ON FERTILIZATION
Authors: Oddo Anna Monroy , Esposito Maria 
Published: May 2004

In the eggs of Arbacia lixula and Paracentrotus lividus an uptake of K occurs during the first 10 minutes following fertilization. Between 10 and 40 minutes K is then released. Both in Arbacia and in Paracentrotus the minimum point of the curve coincides with the nuclear streak stage. A maximum loss of 25 per cent in Arbacia and 20 per cent in Paracentrotus with respect to the amount present in the unfertilized eggs has been found. From 40 minutes up to 1 hour K undergoes a further increase and when the first cleavage sets in the same amount of K is present as in the unfertilized eggs.
By treating the eggs with K-free artificial sea water it has been established that about 60 per cent of the K content of the eggs is in a non-diffusible condition. Also under such conditions the eggs when fertilized are able to take up even the very small amount of K present in the medium that was released by them prior to fertilization.
THE CHEMICAL COMPOSITION AND THE OSMOTIC PRESSURE OF THE AQUEOUS HUMOR AND PLASMA OF THE RABBIT
Authors: Kinsey V. Everett 
Published: May 2004

Measurements were made of the osmotic pressure of plasma, and of aqueous humor taken from the anterior chamber of the right and left eyes and from the posterior chamber of unanesthetized rabbits. Aqueous humor from the anterior chamber was found to be hypertonic to the plasma by approximately 3 mM/liter equivalent of sodium chloride. The aqueous humor from the anterior and posterior chambers of the right and left eyes was isotonic. The concentration of chloride in the anterior and posterior chambers was the same.
The concentration of all the major components of the aqueous humor and plasma has been determined by chemical analysis on fluid samples obtained from unanesthetized rabbits at approximately the same time. The calculated osmotic pressure of the total of these substances in terms of sodium chloride equivalent agrees to within better than 1 per cent of the total osmotic pressure as measured experimentally.
The distribution of some individual anions and cations of the aqueous humor and plasma was determined. This distribution is widely different from that which would obtain at a state of equilibrium. The positive and negative charges carried by the ions in the aqueous humor were approximately equal. Sources of error in the experiments are discussed.
RELATIVE CONCENTRATIONS OF N15 IN URINARY AMMONIA N AND UREA N AFTER FEEDING N15-LABELED COMPOUNDS
Authors: Wu Hsien 
Published: May 2004

Available data on the isotopic ratio
See PDF for Equation
of ammonia (ra)
and that of urea (ru) after a single feeding of glycine, aspartic acid, and ammonium citrate are analyzed. From this analysis the following conclusions are drawn.
1. The isotopic ratio
See PDF for Equation
of ammonia (ra) is always higher than that of urea (ru) in the initial period after a single feeding of isotopic glycine or aspartic acid, but the relation is reversed later. A similar relation probably holds after feeding isotopic ammonia.
2. It is pointed out that the ratio of average ra to average ru depends on the time interval for which urine is collected, on the schedule of feeding, and probably also on the amount taken at each feeding. When the amount fed and the feeding schedule are unknown, theoretical interpretation of the ratio of average ru to average ru is impossible.
3. At the point of maximum isotopic ratio of urea, it is very probably equal to the isotopic ratio of ammonia. A possible explanation is suggested.
THE COMPOSITION AND STRUCTURE OF ISOLATED CHROMOSOMES
Authors: Mirsky A. E. , Ris H. 
Published: May 2004

1. The preparation of isolated chromosomes from liver, kidney, and pancreas has been described.
2. It has been shown that there is no gross cytoplasmic contamination in these preparations.
3. In a microscopic study of isolated chromosomes the same chromosomes have been found in different tissues of the same organism. Since individuality is one of the main characteristics of chromosomes, there can be little doubt that the preparations do, in fact, contain isolated chromosomes.
4. A quantitative study of staining with crystal violet shows that this basic dye competes with histone for the phosphoric acid groups of the DNA in chromosomes. The displacement of histone by protamine has been demonstrated.
5. Preparation of histone-free chromosomes has been described. Removal of histone does not affect the microscopic appearance of chromosomes.
6. The non-histone or residual protein has been prepared from histone-free chromosomes. The quantity of residual protein in a preparation of chromosomes is correlated with the amount of cytoplasm in the cells from which the chromosomes were prepared.
7. The microscopic appearance of chromosomes depends upon the association of DNA with residual protein.
8. Evidence has been given that in a chromosome there are two DNA-containing nucleoproteins; in one DNA is combined with histone, and in the other it is combined with residual protein.
MECHANISMS INVOLVED IN FIBRIN FORMATION
Authors: Boyles Paul W. , Ferguson John H. , Muehlke Paul H. 
Published: May 2004

That the role of thrombin in the conversion of fibrinogen to fibrin is essentially enzymatic, is established not only by the minute amounts of thrombin which are effective but also by the complete independence of fibrin yields and thrombin concentrations over a very wide range of thrombin dilutions and clotting times. The thrombin-fibrinogen reaction, in the phase beyond the "latent period" at least, seems fundamentally "first order." Technical requirements of the experiments leading to these conclusions include: (1) a highly purified (e.g. 97 per cent "clottable") fibrinogen, (2) absence of traces of thrombic impurities in the fibrinogen, (3) absence of fibrinolytic protease contaminant of the thrombin and the fibrinogen, and (4) sufficient stability of the thrombin even at very high dilutions. Four conditions affecting thrombin stability have been investigated.
Fibrin yields are not significantly modified by numerous experimental circumstances that influence the clotting time, such as (1) temperature, (2) pH, (3) non-specific salt action due to electrical (ionic) charges, which alter the Coulomb forces involved in the fibrillar aggregation, (4) specific ion effects, whether clot-accelerating (e.g. Ca++) or clot-inhibitory (e.g. Fe(CN)6''''), (5) occluding (adsorptive) colloids, which have a "fibrinoplastic" action, e.g. (a) acacia and probably (b) fibrinogen which has been mildly "denatured" by salt-heating, acidification, etc.
The data with which several European workers have attempted to substantiate the idea of a two-stage thrombin-fibrinogen reaction with an intermediary "profibrin" (allegedly partly "denatured") have been reanalyzed with controls which lead us to very different conclusions, viz. (1) denaturation and fibrin formation are independent; (2) partial denaturation is "fibrinoplastic" (see above); and (3) conditions of strong salinity and acid pH (5.1) usually do not completely prevent the thrombin-fibrinogen reaction but merely prolong the "latent" phase and lessen the time required for completion of essentially the same reaction (fibrin polymerization) when more favorable clotting conditions are restored.
Thus, our experiments advance the modern concepts concerning the coagulation mechanisms along lines that, for the most part, agree with those of the Harvard physical chemists, and we oppose the European views concerning a two-stage reaction, "profibrin," and "the denaturase theory" of clotting.
THE REVERSIBLE HEAT DENATURATION OF CHYMOTRYPSINOGEN
Authors: Eisenberg Max A. , Schwert George W. 
Published: May 2004

Within a restricted range of pH and protein concentration crystalline chymotrypsinogen undergoes thermal denaturation which is wholly reversed upon cooling. At a given temperature an equilibrium exists between native and reversibly denatured protein. Within the pH range 2 to 3 the amount of denatured protein is a function of the third power of the hydrogen ion activity. The presence of small amounts of electrolyte causes aggregation of the reversibly denatured protein. A specific anion effect has been observed at pH 2 but not at pH 3. Both the reversible denaturation reaction and the reversal reaction have been found to be first order reactions with respect to protein and the kinetic and thermodynamic constants for both reactions have been approximated at pH 2 and at pH 3. Renatured chymotrypsinogen has been found to be identical with native chymotrypsinogen with respect to crystallizability, solubility, activation to δ-chymotrypsin, sedimentation rate, and behavior upon being heated.
Irreversible denaturation of chymotrypsinogen has been found to depend on pH, temperature, protein concentration, and time of heating. Irreversible denaturation results in an aggregation of the denatured protein.
EXPERIMENTS ON THE ROLE OF POTASSIUM IN THE BLOCKING OF NEUROMUSCULAR TRANSMISSION BY CURARE AND OTHER DRUGS
Authors: Fenn Wallace O. , Gerschman Rebeca , Fischer George , Lacy Jane , Bailly Margaret D. , Wright Joan L. 
Published: May 2004

1. Experiments with perfused frog muscles and with isolated frog muscles immersed in Ringer's solution have failed to show any effect of curare in liberating potassium from muscle tissue. This makes it difficult to suppose that the paralytic effect of curare can be attributed to cation exchange between curare and K whereby a labile potassium compound needed for stimulation is removed from the neuromuscular junction.
2. Similar negative results were obtained with dihydro-ß-erythroidine and myanesin.
3. A small liberation of K from perfused muscle does result from treatment with acetylcholine. This is probably due to the contracture of the muscle since the effect is largely eliminated by previous treatment of the muscle with curare. The amount of potassium lost in this way from perfused muscles is too small to detect when muscles are analyzed after immersion in Ringer's solution with and without acetylcholine. It is concluded that there is no significant cation exchange between acetylcholine and K in muscle, but only a small loss of K due to the contracture produced by the acetylcholine.
THE EFFECT OF VARYING THE INTENSITY AND THE DURATION OF PREEXPOSURE UPON FOVEAL DARK ADAPTATION IN THE HUMAN EYE
Authors: Mote F. A. , Riopelle A. J. 
Published: May 2004

The course of foveal dark adaptation was studied as a function of the intensity and duration of preexposure. Four intensities (11,300, 5,650, 1,130, and 565 mL.) and four durations (300, 150, 30, and 15 seconds) were used in all combinations of intensity and duration. The threshold-measuring instrument was a monocular Hecht-Shlaer adaptometer and the threshold measurements were recorded in log micromicrolamberts. There were two subjects and each went through the complete series of intensities and durations five times. The five logarithmic values obtained for each threshold were converted into a geometric mean and these means were the data used in the analysis of the results. The chief results were as follows:—
1. For each subject the final steady threshold value was in the region of 7.0 log µµL.
2. As the intensity, or duration, or both, were increased the initial foveal dark adaptation threshold rose, the slope of the curve decreased, and the time to reach a final steady threshold value increased.
3. For those values of preexposure intensity and time for which the product, I x t, is a constant it was found that for the two higher intensities and two longer durations and also for the two lower intensities and two shorter durations, the dark adaptation curves were the same. For other values of I x t = C the curves were generally not the same.