bluuebunny/crossref_metadata_2025_split huggingface dataset:
LOW LEVEL IMPEDANCE CHANGES FOLLOWING THE SPIKE IN THE SQUID GIANT AXON BEFORE AND AFTER TREATMENT WITH "VERATRINE" ALKALOIDS
Authors: Shanes Abraham M. , Grundfest Harry , Freygang Walter 
Published: May 2004

The increase in conductance, which accompanies the spike in the presence of sea water, is followed by a decrease to below the resting level, here designated as the "initial after-impedance," which lasts 3 msec. and is 3 per cent as great as the increase. Treatment with cevadine usually obliterates the latter but leaves the former essentially unaltered. In addition, the alkaloid gives rise to periodic conductance increases followed by a prolonged, exponentially decaying elevated conductance (the "negativity after-impedance") which correspond closely to potential oscillations and to the negative after-potential. These are also only a few per cent of the major conductance change. Veratridine causes a conductance increase which lasts longer and which also conforms closely with earlier after-potential results.
Preliminary calculations indicate that the negativity after-impedance and the negative after-potential may be due to the subsidence of an elevated chloride permeability. However, no satisfactory explanation is available for the initial after-impedance or for the temporal course of the conductance changes associated with oscillations in membrane potential.
OBSERVATIONS ON THROMBIN INACTIVATION BY HUMAN SERUM
Authors: Mihályi Elemer 
Published: May 2004

The inactivation of thrombin by serum follows a first order kinetics with thrombin concentrations of the order of 20 to 40 units per ml. of serum. With higher thrombin concentrations of 300 to 600 units per ml. of serum, the rate slows down and not the logarithm of the clotting time, but the clotting time itself increases proportionally with the incubation time.
The antithrombic factor is stable at +4°C. for a period of 2 weeks, or for 3 months at –15°C. Heating over 58°C. destroys it rapidly. The heat inactivation has an energy of activation of 121,000 cal.
With low thrombin concentrations the rate of thrombin inactivation increases linearly with increasing serum concentration. The pH optimum of the inactivation is at 8.5. Increasing the temperature increases the rate. The energy of activation of the thrombin destruction by serum is 14,000 cal.
Heparin increases the rate considerably with low thrombin concentrations, but does not affect the rate with high thrombin concentrations. The effect of heparin can be abolished with protamine or toluidine blue. Some other reagents were also tested with respect to their effect upon the rate of inactivation of thrombin by serum.
THE MOLAR EXTINCTION OF RHODOPSIN
Authors: Wald George , Brown Paul K. 
Published: May 2004

The molar extinction of rhodopsin is 40,600 cm.2 per mole equivalent of retinene; i.e., this is the extinction of a solution of rhodopsin which is produced by, or yields on bleaching, a molar solution of retinene. The molar extinctions of all-trans retinene and all-trans retinene oxime have also been determined in ethyl alcohol and aqueous digitonin solutions.
On the assumption that each chromophoric group of rhodopsin is made from a single molecule of retinene, it is concluded that the primary photochemical conversion of rhodopsin to lumi-rhodopsin has a quantum efficiency of 1; though the over-all bleaching of rhodopsin in solution to retinene and opsin may have a quantum efficiency as low as one-half.
On bleaching cattle rhodopsin, about two sulfhydryl groups appear for each molecule of retinene liberated. In frog rhodopsin the —SH:retinene ratio appears to be higher, 5:2 or perhaps even 3:1. Some of this sulfhydryl appears to have been engaged in binding retinene to opsin; some may have been exposed as the result of changes in opsin which accompany bleaching, comparable with protein denaturation.
A QUANTITATIVE STUDY OF METACHROMASY IN SYNOVIAL FLUID AND MUCIN
Authors: Hamerman David J. , Schubert Maxwell 
Published: May 2004

Spectrophotometric measurements on synovial fluid and solutions of mucin and hyaluronate in the presence of methylene blue showed that:
1. Dialyzed synovial fluid was not metachromatic.
2. Albumin and gelatin at a concentration of 1 mg. per ml. inhibited the metachromasy of strong chromotropes.
3. Reduction of the protein of synovial fluid by the use of proteolytic enzymes still did not make the synovial fluid chromotropic.
4. Mucin solutions, with a protein content equal to that of protease-treated synovial fluid, were intensely metachromatic.
5. Sulfur-free hyaluronate produced intense metachromasy.
The evidence presented indicates that in its native state in synovial fluid hyaluronate is either bound or its anionic groups are not entirely free.
THE REACTIVATION OF HEAT-INACTIVATED HYALURONIDASE
Authors: Emmart E. W. , Longley J. B. 
Published: May 2004

1. Following heat denaturation after an hour at boiling temperature bovine testicular hyaluronidase has been shown to undergo spontaneous reactivation.
2. This reactivation is a function of the temperature at which the enzyme solution is maintained.
3. Secondary inactivation was observed to follow a reactivation of the enzyme at all concentrations observed.
4. There is a relationship between hydrolysis by the enzyme and the purity of the substrate. The demonstration of activity of the freshly boiled enzyme by the turbidimetric reduction technique is dependent upon the purity of the substrate.
5. These reactions have been demonstrated using preparations of bovine and avian hyaluronic acid and porcine chondroitin sulfate.
CHANGES IN RESTING POTENTIAL DUE TO A SHIFT OF ELECTROLYTES IN THE CELL PRODUCED BY NON-ELECTROLYTES
Authors: Osterhout W. J. V. 
Published: May 2004

Experiments on Nitella indicate that the resting potential is due chiefly to the outwardly directed diffusion potential of electrolytes which is set up at the inner, non-aqueous, protoplasmic surface surrounding the vacuole. We might therefore expect that any change in the concentration of these electrolytes would affect the resting potential. The experiments described here indicate that this expectation is justified.
When a sucrose solution is applied at one end of the cell and water is placed at another spot, water enters at the latter, passes along inside the cell, and escapes into the sucrose solution, but the electrolytes are unable to escape into the sucrose solution (except very slowly) so that the concentration of electrolytes increases in the region in contact with the sucrose solution. Hence the potential at this spot increases. At the other spot where the water enters, the concentration of electrolytes decreases and the potential at this spot falls off.
The changes can be carried out reversibly without injury to the cell.
ISOLATION OF PURIFIED COPPER PROTEIN FROM HORSE LIVER
Authors: Mohamed Mostafa S. , Greenberg David M. 
Published: May 2004

1. A procedure is described for isolating a copper protein from horse liver in pure form, in a state that appears to be crystalline.
2. This copper protein is colored blue-green, and its copper content varied between 0.3 and 0.4 per cent. No indication of any catalytic properties was obtained in the limited number of tests made. Because of its variable copper content, the protein may function for the storage of copper in the body.
3. The copper could be removed partly from the protein by dialysis against cyanide, and a colorless crystalline protein was obtained by lowering the pH to 5.0, followed by dialysis. The original blue-green color of the protein could be restored by dialysis against copper acetate solution.
SILICON METABOLISM IN DIATOMS
Authors: Lewin Joyce C. 
Published: May 2004

1. Cells of the fresh water diatom Navicula pelliculosa may be grown in a mineral medium containing a low concentration of silicon. When transferred to a fresh silicate solution and incubated under non-growing conditions such deficient cells rapidly take up silicon from the medium.
2. The utilization of silicon is an aerobic process.
3. When deficient cells are washed with distilled water or saline, their ability to utilize silicon is impaired whereas respiration is unaffected.
4. The ability of washed cells to take up silicon can be partially restored with sulfate or ascorbic acid, and is completely restored by Na2S, Na2S2O3, glutathione, l-cysteine, dl-methionine, or ascorbic acid plus sulfate.
5. The sulfhydryl reagent, CdCl2, inhibits silicon utilization of unwashed cells at concentrations which do not affect respiration. This inhibition similarly is reversed by glutathione or cysteine.
6. However, sodium iodoacetate or sodium arsenite inhibits respiration and silicon utilization at the same concentrations.
7. The silicon taken up by deficient cells is deposited at the cell surface as a thickening of the existing silica frustules.
8. Sulfhydryl groups in the cell membrane may be involved in silicon uptake by diatoms.
EXPERIMENTAL VARIATIONS IN SONIC FRAGILITY OF RED CELLS
Authors: Guillet Marilyn , Fowler Richard C. 
Published: May 2004

A magnetostriction oscillator has been used for determining the relative fragility of human red cells to 9000 cycle vibrations under some different environmental conditions. The destruction of the cells is a logarithmic function of time according to the equation
See PDF for Equation.
Hypertonic saline solution, saponin, preheating, alcohol, and ether in subhemolytic concentrations decrease the fragility of human red cells subjected to sonic oscillation. Hypotonic saline, preheating to 50°C. for 3 minutes, and hemolytic concentrations of ether increase the fragility of red cells to 9 kc. vibrations. Following preheating of the cells, and in the presence of saponin the destruction deviates slightly from a true logarithmic rate of hemolysis.
THE ROLE OF HIGH IONIC CONCENTRATIONS IN PROTECTION AGAINST X-IRRADIATION
Authors: Bachofer C. S. , Pottinger M. Aelred 
Published: May 2004

Various levels of protection against x-irradiation damage in bacteriophage T1 may be obtained by the addition of inorganic salts to the aqueous virus suspensions during irradiation.
The highest survival values are obtained with the nitrite salts, and their protective power is attributed primarily to their function as reducing agents.
The nitrate ion shows greater protection than the corresponding sulfate or chloride ions. This may be due in part to the lower energy level of the nitrate ion, by reason of resonance. Since greater expenditure of incident energy is required to raise the ion from the ground state, the energy thus dissipated may be ineffective in the inactivation of virus particles.
The ammonium salts exhibit protection of a different order of magnitude from that of the metallic salts. It is postulated that NH4+ protects in a threefold way: (a) dehydration, (b) reduction, in which the ammonia is oxidized to nitrite and the nitrite to nitrate, and (c) stabilization of the virus protein.
Metallic salts likewise protect, but a point of maximum protection is reached in lower concentrations than in the case of the ammonium salts. After this maximum protection is reached, there is a rapid decline in survival with increased concentration. This prevents protection of the order of magnitude that can be obtained with the ammonium salts. It is postulated that a specific cationic interaction with the phage may be responsible for the decreased protection.
Bacteriophage is protected during x-irradiation by an alkaline pH, in the case of NH4OH. This protection could not be produced with NaOH, presumably because of the greater hydrolysis of the protein components of the virus particle in solutions of NaOH, whereas NH4OH stabilizes the protein.
NUTRITIONAL CONTROL OF SEXUALITY IN CHLAMYDOMONAS REINHARDI
Authors: Sager Ruth , Granick S. 
Published: May 2004

1. Cells of Chlamydomonas reinhardi grown in the light or dark on standard medium require an additional exposure to light in the absence of a nitrogen source, in order to become sexually active. As the culture ages, the light requirement decreases.
2. This light requirement is a function of nitrogen depletion, as shown by the observation that cells from cultures grown to maturity on a low nitrogen medium in the light or in the dark, have no additional light requirement for zygote formation. The withholding of no other component of the medium has this effect.
3. In cells requiring light for zygote formation, the light can be supplied before the mating types are mixed, indicating that light is required, not for mating per se, but for the conversion of vegetative cells to gametes.
4. Gametes can be dedifferentiated to the vegetative state by any nitrogen compound which the cells can use for growth; and by further exposure to light in the absence of a nitrogen source, these vegetative cells can again become gametic.
5. Cells grown at different nitrogen levels become gametic at widely different cell concentrations of nitrogen and carbon and C/N ratios.
6. It is postulated that the role of light in gametic differentiation is indirect, providing by photosynthesis, energy for the mating process and carbohydrates to tie up excess nitrogenous reserves; and that the concentration of some particular nitrogen fraction or compound determines whether or not gametic differentiation is initiated.
USE OF A GLASS ELECTRODE FOR MEASURING RAPID CHANGES IN PHOTOSYNTHETIC RATES
Authors: Rosenberg Jerome L. 
Published: May 2004

1. A continuously recording glass electrode apparatus has been described for measuring carbon dioxide concentration changes in solution. The limits of applicability of the apparatus have been analyzed.
2. The glass electrode apparatus has been used for the measurement of transient rates of photosynthesis by algal suspensions.
3. The decline of the photosynthetic rate in high light at carbon dioxide partial pressures less than 0.5 per cent atmosphere, observed in the glass electrode apparatus, has been confirmed by steady state experiments in which flowing gas streams were analyzed.
REVERSAL OF THE STREPTOMYCIN INJURY OF ESCHERICHIA COLI
Authors: Wasserman Aaron E. , Lessner James M. , West Margaret K. 
Published: May 2004

The number of viable Escherichia coli in a young, actively growing culture is decreased approximately 99.9 per cent by a 30 second exposure to 25 ϕg. streptomycin/ml. The injury induced by the antibiotic is only potentially lethal, however, and may be reversed by subculture within 5 minutes into fresh culture medium, NH4NO3, NH4Cl, (NH4)2HPO4, NH4 citrate, and NH4 tartrate. Subculturing into water, glucose, or MgSO4 results in a more marked decrease in the number of viable organisms. In KNO3, NaNO3, K2HPO4, and Na2SO4 solutions reversal occurs first, followed by a rapid decrease in viability.
True reversal of the streptomycin injury takes place, as demonstrated by the rapid rate of recovery to the viable count of the original culture. Development of resistance has been eliminated as the cause of regrowth since the streptomycin sensitivity of recovered cultures remained the same as that of the original culture.
The use of water as diluent for viability determinations potentiates the lethal effect of streptomycin activity. Several compounds, at various dilutions, substituted for water as the diluent gave rise to four types of responses, group I, NH4NO3, NH4Cl, KNO3, NaNO3, Ca(NO3)2, showed complete reversal of the streptomycin injury at all levels of the salts tested, from 0.01 to 0.5 M concentrations. Group II, NaCl and K2HPO4 showed complete reversal at 0.03 and 0.1 M. Group III, glucose and urea allowed complete reversal at 0.5 M. Group IV, glycerol and glycerine showed no reversal at 0.5 M concentration.
The reversal of the streptomycin injury to young actively growing bacteria is suggested as a tool for studying the pathology of the injury to the cells.
KINETICS OF AMINO ACID INCORPORATION INTO SERUM PROTEINS
Authors: Green H. , Anker H. S. 
Published: May 2004

1. The effect of varying body temperature on the rate of amino acid incorporation into serum protein does not give support to the idea that the rate of this process is adjusted in vivo to restore those protein molecules destroyed by thermal denaturation. The experimentally observed Q10 was about 3.9.
2. When amino acids are injected into the blood of animals in a steady state of serum protein turnover, a period of time elapses before these amino acids can be found in the serum proteins. This has been called transit time. At a given temperature (31°) it is the same in rabbits, turtles, and Limulus (1 hour). In rabbits and turtles it has a Q10 of 3.2. It appears to be specifically related to the process of synthesis (or release) of serum proteins.
3. It was not possible to affect the transit time or the incorporation rate by the administration of amino acid analogues.
ACTIVE SODIUM UPTAKE BY THE TOAD AND ITS RESPONSE TO THE ANTIDIURETIC HORMONE
Authors: Kalman Sumner M. , Ussing Hans H. 
Published: May 2004

A method has been described in which sodium uptake may be studied in the intact, anesthetized toad. Sodium uptake is determined by "counting" the whole animal in a special chamber after suspending it in a frog Ringer bath containing radioactive Na24. The effects of subcutaneous injection of the neurohypophyseal antidiuretic factor were studied with these results:
1. There was a pronounced increase in sodium influx following treatment with the hormone.
2. Sodium outflux was small in both experimental and control animals.
3. There was an increase in water uptake in both experimental and control animals after 1 hour in the bathing solution. This increase was greater in the experimental toads in which it is believed to be related, at least in part, to sodium transport.
4. Potentiometric measurements were made on the skin membrane potential of the whole animal while suspended in bathing solutions. These results were in essential agreement with those found for isolated frog skin. However, there was no apparent influence of the antidiuretic factor on the skin potential.
POTASSIUM TRANSPORT IN HUMAN ERYTHROCYTES: EVIDENCE FOR A THREE COMPARTMENT SYSTEM
Authors: Solomon A. K. , Gold G. Lennard 
Published: May 2004

Whole human blood is incubated for periods of ½ to 3 hours with K42 at 37°C. At the close of this period, called pre-incubation, the plasma is removed from the cells and the cells, now become radioactive, are again incubated in a mixture of plasma and buffer for periods of up to 10 additional hours. The time course of the K42 activity of the incubating medium is followed. Characteristically, after 2 hours of pre-incubation, the activity in the medium rises to a peak about 1 and ½ hours after resuspension, and then falls slowly until at 10 hours it is very close to its initial value at the beginning of the resuspension interval. This transient rise in K42 activity in the medium is taken to indicate that the red cell does not consist of a single uniform K compartment, but contains at least two compartments. Thus one cellular compartment contains a reservoir of high specific activity K which provides the specific activity gradient necessary to drive the K42 content of the medium to its transient peak. Experiments with Na indicate that its behavior in this respect is unlike that of K.
The experimental data are matched to a simple model system which is capable of theoretical analysis with the aid of an analogue computer. The model system, whose characteristics agree fairly well with those observed experimentally on red cell suspensions, comprises two intracellular compartments, one containing 2.35 m.eq. K/liter blood, and the other 44.1 m.eq. K/liter blood. The plasma K content is 2.64 m.eq./liter blood. The flux between plasma and the smaller intracellular compartment is 0.65 m.eq. K/liter blood hour; that between the smaller and the larger intracellular compartment, 1.77 m.eq. K/liter blood hour; and that between the larger intracellular compartment and the plasma is 0.34 m.eq. K/liter blood hour.
SOME OBSERVATIONS ON PROTEIN METABOLISM IN CHROMOSOMES OF NON-DIVIDING CELLS
Authors: Allfrey V. G. , Daly M. M. , Mirsky A. E. 
Published: May 2004

1. The metabolism of chromosomal proteins has been studied in the pancreas, liver, and kidney of adult mice (a) by measuring the rates of glycine-N15 incorporation into histones and residual chromosome fractions, and (b) by measuring the extent to which N15, once incorporated into chromosomal proteins, is retained.
2. The uptake of isotopic nitrogen by these nuclear constituents was compared with that of protein fractions prepared from the cytoplasm by differential centrifugation in sucrose solutions. One such fraction, which comprises the bulk of the ribosenucleoprotein of the cell sediments as a pellet on high speed centrifugation. The supernatant remaining after this centrifugation is a fraction which, in the pancreas, is rich in the secretory enzymes synthesized by the cell.
3. A comparison of the rates of glycine-N15 uptake shows that cytoplasmic ribonucleoprotein is the most active of the protein fractions analyzed. In the pancreas it meets the conditions required of a precursor for the secretory enzymes of the supernate.
4. In all tissues considered the rates of glycine-N15 uptake into histone and residual chromosome fractions are lower, that for histone being the lowest of any of the protein components considered and that for residual protein approximating the over-all rate for cytoplasmic protein.
5. The effects of feeding and fasting upon glycine-N15 incorporation have been studied. In the pancreas, feeding causes a sharp increase in N15 uptake by the mixed tissue proteins and by the nucleoprotein and supernatant protein of the cytoplasm. There is a parallel increase in N15 uptake by the chromosomal constituents—histone and residual protein.
6. A parallelism between N15 uptake in cytoplasmic and chromosomal proteins is also observed in the liver and kidney when over-all protein metabolism is altered by feeding and fasting.
7. The responsiveness of the histones and residual proteins to changes in the environment has also been demonstrated in N15 retention experiments. The loss of isotope once incorporated into chromosomal proteins is much more rapid in fed than in fasted animals.
RELATIONSHIP BETWEEN THE ACTIVITY OF THE SUCCINOXIDASE SYSTEM AND THE RATE OF OXYGEN CONSUMPTION DURING THE EMBRYONIC DEVELOPMENT OF THE MEALWORM, TENEBRIO MOLITOR LINNAEUS
Authors: Ludwig Daniel , Barsa Mary C. 
Published: May 2004

1. Readings were made on the rates of oxygen consumption and on the activities of the succinoxidase system of eggs of the mealworm for each day of embryonic development at 30°C.
2. The rate of oxygen consumption, expressed as microliters/50 eggs/hour, was low (4.89) in newly laid eggs. It rose to 7.41 during the next 24 hours, remained at this level for the next 2 days, and then increased during the remainder of the embryonic period reaching a high value of 14.79 at the time of hatching.
3. The activity of cytochrome oxidase in eggs from newly emerged beetles, expressed as Δ log [Cy Fe++]/minute, remained at a value of 0.042 during the first half of the embryonic period, increasing to 0.233 during the latter half of this period.
4. The activity of succinic dehydrogenase showed the same series of changes except at much lower values. Expressed as Δ log [Cy Fe+++]/minute, they ranged from 0.010 in the newly laid egg to 0.034 at the end of the embryonic period.
5. The activity of cytochrome oxidase of the egg was found to decrease with parental age. Eggs from newly emerged beetles had activity values considerably higher than those of beetles 6 or 8 weeks after emergence. However, no comparable changes were noted in the activity of succinic dehydrogenase or in the rate of oxygen consumption. These observations suggest that cytochrome oxidase is not a rate-limiting enzyme in the respiratory metabolism of the mealworm egg.