bluuebunny/crossref_metadata_2025_split huggingface dataset:
THE EFFECT OF CALCIUM AND OTHER IONS ON THE AUTOCATALYTIC FORMATION OF TRYPSIN FROM TRYPSINOGEN
Authors: McDonald Margaret R. , Kunitz M. 
Published: May 2004

Crystalline trypsinogen is completely transformed into trypsin by means of trypsin in the presence of calcium salts. The process follows the course of a pure autocatalytic unimolecular reaction.
In the absence of calcium salts, the autocatalytic formation of trypsin from trypsinogen is complicated by the transformation of part of the trypsinogen into an inert protein which cannot be changed into trypsin by any known means.
Salts increase or decrease the rate of both reactions so that the ultimate amount of trypsin formed varies with the nature and concentration of the salt used. With equivalent concentrations of salt the percentage of trypsinogen changed into trypsin is greatest in the presence of calcium ion followed in order by strontium; magnesium and sodium; rubidium, ammonium, lithium, and potassium; caesium and barium. With the anions the largest percentage of trypsinogen transformed into trypsin was found with the acetate, sulfate, oxalate, citrate, tartrate, fluoride, and chloride ions followed in order by bromide, nitrate, and iodide.
The formation of inert protein is completely suppressed by concentrations of calcium ion greater than 0.02 M.
OSMOTIC PROPERTIES OF THE EGG CELLS OF THE OYSTER (OSTREA VIRGINICA)
Authors: Lucké Balduin , Ricca R. A. 
Published: May 2004

Investigations of the osmotic properties of oyster eggs by a diffraction method for measuring volumes have led to the following conclusions:
1. The product of cell volume and osmotic pressure is approximately constant, if allowance is made for osmotically inactive cell contents (law of Boyle-van't Hoff). The space occupied by osmotically inactive averages 44 per cent of cell volume.
2. Volume changes over a wide range of pressures are reversible, indicating that the semipermeability of the cell during such changes remains intact.
3. The kinetics of endosmosis and of exosmosis are described by the equation,
See PDF for Equation,
where dV is rate of volume change; S, surface area of cell, (P-Pe), the difference in osmotic pressure between cell interior and medium, and K, the permeability of the cell to water.
4. Permeability to water during endosmosis is 0.6µ3 of water per minute, per square micron of cell surface, per atmosphere of pressure. The value of permeability for exosmosis is closely the same; in this respect the egg cell of the oyster appears to be a more perfect osmometer than the other marine cells which have been studied. Permeability to water computed by the equation given above is in good agreement with computations by the entirely different method devised by Jacobs.
5. Permeability to diethylene glycol averages 27.2, and to glycerol 20.7. These values express the number of mols x 10–15 which enter per minute through each square micron of cell surface at a concentration difference of 1 mol per liter and a temperature of 22.5°C.
6. Values for permeability to water and to the solutes tested are considerably higher for the oyster egg than for other forms of marine eggs previously examined.
7. The oyster egg because of its high degree of permeability is a natural osmometer particularly suitable for the study of the less readily penetrating solutes.
THE EFFECT OF TEMPERATURE AND OF LYSIN CONCENTRATION ON THE ACCELERATION OF HEMOLYSIS
Authors: Ponder Eric 
Published: May 2004

The acceleration of saponin hemolysis by benzene, indol, and nonyl alcohol has been investigated as a function of temperature, and it has been found that these accelerators have negative temperature coefficients. This points to their being concentrated at the cell surface, and to the surface being the seat of their accelerating action.
It is shown that the accelerating power of indol (used as a typical accelerator) is constant so long as the lysin in the system is capable of producing lysis per se, but that the acceleration falls off when only sublytic concentrations are present. The relations are expressed in a series of equations, and explained in terms of the reactions among the accelerator, the lysin, and the membrane component, which breaks down in spots, rather than uniformly, when lysis occurs. The argument involves a consideration of the idea that a monolayer of lysin at the cell surface is necessary for hemolysis, of Abramson's hypothesis of "key spots" on the surface, of the rate of escape of hemoglobin from the hemolyzing cell, and of the results of electrophoretic and impedance measurements. The existing theory of the kinetics is extended by introducing the idea of a variation in resistance from point to point in the cell membrane; in this form it describes the situation so far as is at present known, and shows that the results of the various methods of investigation are consistent with each other. The only idea discussed which seems to have little foundation is that lysis is determined by the formation of a monolayer of lysin at the cell surface; when this occurs, it must do so only as a special case. Finally, a semi-quantitative description of the frequency distribution of the resistances in the membrane is derived from existing data. The variation in resistance which it is necessary to assume is quite small, as might be expected in the case of a membrane with a regular ultra-structure.
P32 UPTAKE BY NUCLEI
Authors: Marshak A. 
Published: May 2004

1. A method for isolating nuclei in quantity from mammalian tissues is described.
2. The rate of uptake of radioactive phosphorus by nuclei is found to be quite rapid. The phosphorus was shown not to be taken up by exchange.
3. Nuclei of tumors accumulate more radioactive phosphorus than normal liver nuclei. This was shown to be due to mitotic activity and not a form of metabolism peculiar to tumor cells.
4. The specific activities of nuclei and cytoplasm are compared.
5. 60 to 70 per cent of the nuclear radioactive phosphorus is present as nucleoprotein from 1 hour to 5 days after it is administered. In the lymphoma nuclei 90–95 per cent of the phosphorus is in the nucleoprotein fraction from 1–5 days after it is administered.
6. The specific activities of the nucleoprotein, lipid, and acid-soluble fractions of liver and tumor nuclei are compared.
7. From the rate of P32 uptake by nuclei it is calculated that a new lymphoma nucleus is synthesized on the average once every 27 hours. This is in agreement with the observed rate of growth of the tumor.
8. In the lymphoma nucleus it is calculated that 7 x 104 molecules of tetranucleotide are synthesized per second.
9. Irradiation with 200 r. x-rays alters the distribution of P32 in the lymphoma cell, markedly increasing the concentration in the nucleus shortly after irradiation. The P32 concentration in the cytoplasm decreases with time after irradiation. It is suggested that the altered distribution is correlated with the inhibition of mitosis produced by the x-rays.
10. Continual synthesis of nucleoprotein takes place even in nuclei of cells which do not undergo mitosis.
THE STRUCTURE OF THE COLLODION MEMBRANE AND ITS ELECTRICAL BEHAVIOR
Authors: Sollner Karl , Carr Charles W. , Abrams Irving 
Published: May 2004

1. Theoretical considerations lead to the conclusion that dissociable acidic groups present to a varying extent in different collodion preparations determine the electrochemical behavior of membranes cast from these preparations. It is further reasoned that the base exchange capacity of the collodion surfaces is the true quantitative measure of the abundance of the dissociable groups.
2. The concept of base exchange capacity and the base exchange method are discussed. The conditions which allow a purposeful application of the latter are stated.
3. The base exchange properties of a number of fibrous collodion preparations of different origins and after various types of treatment, having widely varying electrochemical activities, are determined.
4. With the chemical (titration) and physical (electrometric) methods employed, no regular correlation can be found between electrochemical activity and base exchange. The base exchange capacity which is necessary to cause even great electrochemical activity of collodion is extremely small.
5. Measurable to high base exchange capacity always seems to be associated with good or high electrochemical activity; but base exchange capacity too low to be definitely measurable with the available methods may be found with collodion preparations of high as well as with preparations of low electrochemical activity.
6. The bearing of these results upon the problem of the spatial and electrical structure of the collodion membrane is indicated briefly.
STIMULATION OF CELLS BY INTENSE FLASHES OF ULTRAVIOLET LIGHT
Authors: Harvey E. Newton 
Published: May 2004

A study has been made of the effect of sudden intense flashes of ultraviolet light, acting on a wide variety of cells and tissues, with special reference to stimulation.
The flashes are obtained by a high voltage condenser discharge through a quartz mercury vapor sterilamp, using the method of Rentschler. The lethal effect of a single such discharge is widespread among unicellular organisms.
Medullated nerves and whole muscles are not visibly stimulated, because of absorption by connective tissue. Single muscle fibers undergo immediate contracture in 50 per cent of the experiments.
Nitella cells are stimulated, the effect depending on the dosage. Weak ultraviolet flashes slow or stop cyclosis reversibly. Strong flashes stop cyclosis reversibly with the appearance of a local or a propagated action potential. Very strong flashes kill the Nitella cells.
The effect of single flashes on myonemes, oscillatory movement, ameboid movement, cilia, flagella, and bioluminescence is described in the text.
PURIFICATION AND CRYSTALLIZATION OF DIPHTHERIA ANTITOXIN
Authors: Northrop John H. 
Published: May 2004

Purified preparations of diphtheria antitoxin have been obtained by digestion of the toxin-antitoxin complex with trypsin, followed by fractional precipitation with ammonium sulfate. The various fractions obtained in this way are all 90 per cent or more precipitated by diphtheria toxin but combine with different quantities of the toxin.
The fraction precipitated between 0.33 and 0.5 saturated ammonium sulfate is homogeneous by electrophoresis and ultracentrifuge but does not have constant solubility.
A small amount of a more soluble fraction has been obtained which does have constant solubility and satisfies the criteria of a pure protein. This protein crystallizes readily in poorly formed thin plates. It is very unstable and reverts to a less soluble non-crystallizable form. It has a sedimentation constant of 5.7 x 10–13 and a molecular weight of 90,500. It has an antitoxic value of 700–900 flocculation units per mg. protein nitrogen and has an antitoxic value by the protection test of about 700 units per mg. protein nitrogen.
The precipitation range of the purified antitoxin with purified toxin is much wider than that with crude preparations.
PURIFIED DIPHTHERIA ANTITOXIN IN THE ULTRACENTRIFUGE AND IN THE ELECTROPHORESIS APPARATUS
Authors: Rothen Alexandre 
Published: May 2004

Ultracentrifugation studies of diphtheria antitoxin showed that:
1. Purified antitoxin of high activity obtained from horse plasma without enzymatic treatment has exactly the same sedimentation constant as the globulin fraction obtained in a similar way from normal horse plasma s20water = 6.9 x 10–13.
2. Purified antitoxin obtained with trypsin digestion of the toxin-antitoxin complex has a sedimentation constant of s20water = 5.5 ± 0.1 x 10–13, a diffusion constant of D20water = 5.76 x 10–7, and a molecular weight of about 90,000.
Electrophoresis experiments demonstrated that:
1. The trypsin-purified antitoxin has an isoelectric point not far from pH 7.0.
2. The reversible spreading noticed at about pH 7.3 cannot be attributed to heterogeneous preparation.
3. The large increase in the γ-globulin fraction occurring during immunization consists either of antitoxin of various degrees of activity or of some inert protein in addition to the antitoxin.
QUANTITATIVE CHEMICAL STUDIES ON HEMOLYSINS
Authors: Heidelberger Michael , Treffers Henry P. 
Published: May 2004

1. Total antibody in hemolysins may be estimated from the nitrogen added to sheep stromata suspensions.
2. The method is applied to a number of hemolysins and a correlation, valid to within 20 per cent, established between hemolytic titer and total antibody.
3. When stromata combine with antibody in the presence of guinea pig complement they may take up at least 80 per cent of their weight of complement combining component(s).
CERTAIN ENZYMATIC ACTIVITIES OF NORMAL AND MOSAIC INFECTED TOBACCO PLANTS
Authors: Wynd F. Lyle 
Published: May 2004

The lower leaves of tobacco plants were inoculated with leaf mosaic virus and the activities of oxygenase, peroxidase, catalase, and invertase were followed in leaves of comparable age at intervals of 2 or 3 days over a period of 21 days.
The inoculated leaves exhibited a great decrease relative to normal tissue in the activity of oxygenase and peroxidase on the 6th day. Younger leaves showed this minimum at a progressively later date. A great decrease in the activities of these enzymes was attained by the 14th to the 18th day. This maximum was followed by a decrease.
Catalase exhibited an increased activity which reached a maximum at about the 8th day. A second maximum was observed on the 16th to the 18th day.
Invertase reached a minimum, relative to normal plants, on about the 8th day. A second minimum was approached on the 16th to the 18th day.
These data show that profound disturbances in the physiology of infected plants occur many days before the leaf juice attains an infectious concentration of virus. The observed activities could not be due therefore to metabolic activities of the virus particles themselves.
Since infectivity is attained only after a period of profound physiological disturbance, it seems possible that the virus protein develops as a product of abnormal metabolism.
THE METABOLISM OF TISSUE CULTURES
Authors: Wilson Hildegard , Jackson Elizabeth B. , Brues Austin M. 
Published: May 2004

1. The metabolism of chick embryo tissues has been followed by analysis of the culture media after various periods of incubation in roller bottles.
2. The initial rate of glucose utilization is increased by increasing glucose in the medium from 100 to 500 mg. per cent. Total glucose used can be increased in the same way or by daily addition of small amounts. Glucose is used in greatest amount when the medium containing 100 mg. per cent is replaced daily.
3. Although glucose consumption appears necessary for survival of cultures it may be used at a rate far in excess of that required for life and maximal growth. Complete blocking of mitosis by colchicine does not alter the rate of glucose utilization.
4. Proteolytic activity of the cultures is shown by an increase in the amino nitrogen of the peptone medium after incubation with tissue.
5. Utilization of nitrogen from an amino acid medium is shown by a decrease in the amino nitrogen of this medium. Cells obtaining their nitrogen from amino acids proliferate as rapidly as those grown in a medium identical except for the substitution of peptone, but the cell type is markedly different, in that embryo muscle forms cells resembling regenerating adult muscle.
6. Lactic acid was formed in both the presence and absence of glucose. Its formation increased with increased glucose utilization. There is some evidence that lactate may be utilized, and that it favors growth in the absence of glucose.
7. Added pyruvate was rapidly metabolized by the tissues. It, too, favors growth slightly in the absence of glucose.
PANTOTHENIC ACID AND THE UTILIZATION OF GLUCOSE BY LIVING AND CELL-FREE SYSTEMS
Authors: Teague Peyton C. , Williams Roger J. 
Published: May 2004

1. Added pantothenic acid was found to have no appreciable effect on the fermentation of glucose when used in conjunction with preparations of dialyzed yeast maceration juice or acetone-precipitated yeast maceration juice.
2. Addition of pantothenic acid failed to affect the rate of phosphorylation of glucose or the rate of decarboxylation of pyruvic acid by yeast maceration juice.
3. Pantothenic acid showed no effect on the rate of glycolysis by homogenized deficient chick tissues.
4. The accelerating effect of pantothenic acid on fermentation by deficient yeast cells was found to be accompanied by a "binding" of pantothenic acid by the yeast cells.
THE VALENCE OF CORPUSCULAR PROTEINS
Authors: Gorin Manuel H. , Mover Laurence S. 
Published: May 2004

By the use of two extreme models: a hydrated sphere and an unhydrated rod the valence (net charge) of corpuscular proteins can be successfully calculated from electric mobility data by the Debye-Hückel theory (modified to include the effect of the ions in the ion atmosphere) in conjunction with the electrophoretic theory of Henry. As pointed out by Abramson, this permits a comparison with values for the valence from titration data.
Electrometric titration measurements of serum albumin B (Kekwick) have been determined at several ionic strengths. These results, together with the available data in the literature for serum albumin B, egg albumin, and ß-lactoglobulin have been used to compare values for the valence calculated from measurements of titration, electrophoresis, and membrane potentials. The results indicate that the usual interpretation of titration curves is open to serious question. By extrapolation of the titration data to zero ionic strength and protein concentration, there results an "intrinsic" net charge curve describing the binding of H+ (OH-) ion alone. This curve agrees closely, in each case, with values of the valence calculated from mobility data (which in turn are in close accord with those estimated from membrane potential measurements). The experimental titration curves in the presence of appreciable quantities of ions and protein deviate widely from the ideal curve. It is suggested that, under these conditions, binding of undissociated acid (base) leads to erroneous values for the net charge. This binding would not affect the electrophoretic mobility.
Values of the net charge obtained by the two extreme models from electrophoretic data are in agreement within 15 to 20 per cent. The agreement between the cylindrical model and the titration data is somewhat better in each case than with the sphere; i.e., this comparison enables a choice to be made between asymmetry and hydration in the interpretation of results from sedimentation and diffusion measurements on proteins. It is concluded that the proteins discussed here are somewhat asymmetric and also hydrated.
ENERGY, QUANTA, AND VISION
Authors: Hecht Selig , Shlaer Simon , Pirenne Maurice Henri 
Published: May 2004

1. Direct measurements of the minimum energy required for threshold vision under optimal physiological conditions yield values between 2.1 and 5.7 x 10–10 ergs at the cornea, which correspond to between 54 and 148 quanta of blue-green light.
2. These values are at the cornea. To yield physiologically significant data they must be corrected for corneal reflection, which is 4 per cent; for ocular media absorption, which is almost precisely 50 per cent; and for retinal transmission, which is at least 80 per cent. Retinal transmission is derived from previous direct measurements and from new comparisons between the percentage absorption spectrum of visual purple with the dim-vision luminosity function. With these three corrections, the range of 54 to 148 quanta at the cornea becomes as an upper limit 5 to 14 quanta actually absorbed by the retinal rods.
3. This small number of quanta, in comparison with the large number of rods (500) involved, precludes any significant two quantum absorptions per rod, and means that in order to produce a visual effect, one quantum must be absorbed by each of 5 to 14 rods in the retina.
4. Because this number of individual events is so small, it may be derived from an independent statistical study of the relation between the intensity of a light flash and the frequency with which it is seen. Such experiments give values of 5 to 8 for the number of critical events involved at the threshold of vision. Biological variation does not alter these numbers essentially, and the agreement between the values measured directly and those derived from statistical considerations is therefore significant.
5. The results clarify the nature of the fluctuations shown by an organism in response to a stimulus. The general assumption has been that the stimulus is constant and the organism variable. The present considerations show, however, that at the threshold it is the stimulus which is variable, and that the properties of its variation determine the fluctuations found between response and stimulus.
RESPIRATORY EFFECTS UPON THE VISUAL THRESHOLD
Authors: Wald George , Harper P. V. , Goodman H. C. , Krieger H. P. 
Published: May 2004

Measurements are reported of the effects of respiratory stresses upon the absolute threshold of peripheral (rod) vision. Since subjects were kept wholly dark adapted and the photochemical system of the rods therefore stationary, the changes recorded may be assumed to have originated more centrally. To this degree the measurements provide a quantitative index of central nervous imbalance.
Breathing room air or 32 to 36 per cent oxygen at about double the normal rate causes the visual threshold to fall to approximately half the normal value within 5 to 10 minutes.
This change is due primarily to alkalosis induced by the hyperventilation, and can be abolished or reversed by adding carbon dioxide to the inspired mixtures. Normal or rapid breathing of 2 per cent carbon dioxide causes no change in threshold; with 5 per cent carbon dioxide the threshold is approximately doubled.
Breathing 10 per cent oxygen at the normal rate also approximately doubles the threshold. This effect is compensated in part by rapid breathing. When 10 per cent oxygen is breathed at twice the normal rate the threshold usually falls at first, then slowly rises to supernormal levels.
Due primarily to variations in their breathing patterns subjects yield characteristically different responses on sudden exposure to low oxygen tensions with breathing uncontrolled. The threshold may either rise or fall; and on release from anoxia it may rise, or fall to normal or subnormal levels. The threshold adjusts to anoxia rapidly; exposures lasting 5 to 6 hours do not produce greater or more persistent changes than those of much shorter duration.