bluuebunny/crossref_metadata_2025_split huggingface dataset:
STUDIES ON THE RIGOR RESULTING FROM THE THAWING OF FROZEN FROG SARTORIUS MUSCLE
Authors: Perry S. V. 
Published: May 2004

1. The rigor which takes place when completely frozen frog sartorius muscle is thawed ("thaw rigor"), is accompanied by a decrease in length of 70 per cent and a loss in weight of 35 per cent, whether the muscle is frozen in the resting or the exhausted condition, or during isometric tetanus. Muscle tetanized to maximal shortening shows a loss in weight of 25 per cent on thawing.
2. A load of 8 gm. is sufficient to prevent the decrease in length on thawing, but after its removal the muscle will shorten almost to the normal extent.
3. Inhibitors such as azide, cyanide, 2:4 dinitrophenol, p-chloromercuribenzoate, Cu, and hydrogen peroxide, when used for periods not exceeding 1 hour, have little effect on the shortening; although in some cases these poisons render the muscle inexcitable.
4. Muscles poisoned with iodoacetic acid and stimulated to exhaustion, or maintained at fixed length in nitrogen, show little or no shortening on thawing. ATP can produce shortening in the muscles in which it has been prevented.
5. The phenomenon is considered to be due to an in situ synaeresis of the actomyosin of the myofibrils. As a result of the disorganisation of the muscle protoplasm produced by the freezing and subsequent thawing, the ATP, which must be bound or localized in the resting muscle, can act on the myofibril in a similar manner to its in vitro effect on the actomyosin thread.
THE CYTOCHROME SYSTEM IN THE CECROPIA SILKWORM, WITH SPECIAL REFERENCE TO THE PROPERTIES OF A NEW COMPONENT
Authors: Sanborn Richard C. , William Carroll M. 
Published: May 2004

1. In the majority of tissues in the cecropia silkworm, cytochromes b and c are apparently absent, being replaced by a hitherto undescribed component which we have tentatively termed cytochrome x.
2. Spectroscopically, the new cytochrome is characterized in the reduced state by a broad and indivisible absorption band extending from 551 to 562 mµ.
3. The enzyme can be demonstrated only in the larval stage of the insect and undergoes breakdown prior to pupation. It occurs in highest concentration in the walls of the larval midgut and resists extraction, being apparently bound to subcellular particles.
4. Evidence is presented, based on spectroscopic and manometric studies in the presence of various substrates and inhibitors, that cytochrome x is a single component which mimics certain of the properties of cytochromes b and c and of succinic dehydrogenase.
5. Detailed studies served to differentiate cytochrome x from the cytochromes b1 and b2 which it resembles spectroscopically.
6. On the basis of spectroscopic studies at the temperature of liquid air, it is concluded that cytochrome x closely resembles, and may be identical with, the component which Keilin has recently described as cytochrome e.
ENZYMATIC HYDROLYSIS OF SOLUBLE CELLULOSE DERIVATIVES AS MEASURED BY CHANGES IN VISCOSITY
Authors: Levinson Hillel S. , Reese Elwyn T. 
Published: May 2004

Observation of changes in fluidity is presented as a method for following the enzymatic hydrolysis of soluble cellulose derivatives. The activity of different cell-free enzyme preparations may be compared by this method, providing certain precautions are observed.
In general, results obtained by use of the fluidity method are similar to those obtained using the reducing sugar technique, indicating that the same enzyme system is measured by the two methods.
Changes in the DP of the substratum may be followed within certain limits of molecular size. Results indicate that a random splitting of CMC occurs during enzymatic hydrolysis, with a concomitant decrease in intrinsic viscosity and an increase in reducing sugars.
Certain inadequacies of the cellulose-cellobiose-glucose theory, together with more recent findings, have led to the postulation of an alternate explanation of the mechanism of cellulose hydrolysis.
ACCUMULATION OF POTASSIUM BY HUMAN RED CELLS
Authors: Ponder Eric 
Published: May 2004

1. A method is described for measuring the accumulation of K at 37°C. by washed human red cells in glucose-containing systems in which the pH is kept constant, the K content of the cells being compared with that of the cells of systems which contain no added glucose but which are otherwise treated similarly.
2. In systems containing added glucose, the accumulation of K begins shortly after the cells have been warmed to 37°C., proceeds to a maximum which is reached after about 10 hours, and then falls exponentially. The maximum rate of accumulation is found during the first 3 hours. In systems which contain no added glucose, the K content of the cells appears to decrease exponentially with time for about 18 to 24 hours; thereafter the K content of the cells may decrease rapidly and the systems may show considerable hemolysis. Sometimes a small accumulation effect is observed during the first 2 to 3 hours; this may be the result of the washed cells not having been completely freed of glucose.
3. The accumulation process proceeds at its maximum rate at pH 7.4 to 7.6, which is also the pH at which the K loss from the red cells is at a minimum in systems containing no added glucose.
4. When red cells are stored at 4°C. for increasing lengths of time, the storage is accompanied by increasing K loss and the maximum rate of accumulation observed when the cells are warmed to 37°C. at first becomes greater. If the storage at 4°C. is continued for more than 3 to 4 days, the rate of the accumulation which occurs at 37°C decreases again, the accumulation mechanism showing progressive deterioration with time even at low temperatures. This deterioration has a counterpart in the progressive deterioration (deduced from the analysis of the curves relating K content and time) of the accumulation mechanism with time at 37°C.
5. The accumulation of K occurs at a maximum rate when the concentration of glucose in the system is between 50 and 200 mg./100 ml. Its temperature coefficient over the range 27–37°C. is 2.4. In the presence of glucose and at pH 7.6, accumulation of K takes place from isotonic mixtures of KCl and LiCl or of KCl and CsCl only a little less actively than from mixtures of KCl and NaCl; i.e., the accumulation of K under optimum conditions seems to be an active process which is at least partly independent of the excretion of Na.
THE SIGNIFICANCE OF REGRESSION LINE SLOPE CHANGES IN THE QUANTITATIVE TITRATION OF COMPLEMENT COMPONENTS
Authors: Waksman Byron H. 
Published: May 2004

The hypothesis is discussed that dissociable complexes are formed between elements of a test complement (C') and the reagent used to titrate it for a particular component.
Calculations are presented which demonstrate that such complex formation may give considerable changes in slopes of percentage hemolysis-log dose regression lines obtained with mixtures of C' and reagent.
It is shown that marked change of slope may occur with relatively little change in the value of the 50 per cent intercept.
BIOLOGIC SIGNIFICANCE OF THE STRUCTURE OF HYDROCARBONS
Authors: Ettisch G. 
Published: May 2004

1. The biologic experiments with the links of the methane series—n-pentane, n-hexane, n-heptane, n-octane, i-octane, and pentene—gave these qualitative results: (a) The higher the number of CH2 groups, the longer the chain, the longer the average lifetime of the animal. (b) The ramified chain does not appear to act differently from the saturated straight chain with the same number of C atoms. (c) One double bond within the chain shortens the lifetime to a considerable degree.
2. The quantitative discussion shows that the lifetimes depend exponentially on the molecular weight.
3. Qualitatively the hypothesis is supported that with rising molecular weight the concentration of CH2 groups within the animal diminishes according to the vapor pressure or the thermodynamic potential. However, lifetime and these physical properties obey different functions.
4. These physical properties are of high biologic importance. But they are not sufficient to explain the biologic effects quantitatively.
TISSUE CULTURE STUDIES
Authors: Hull Wayne , Perrone J. C. , Kirk Paul L. 
Published: May 2004

The use of acetyl-3-pyridine and pyridine-3-sulfonic acid as analogues for nicotinic acid has been tested with tissue cultures of embryonic chick heart. Both roller tube and Carrel flask cultures were employed. Cell migration, appearance of the cells, and the uptake of tracer P32 were used as criteria for the action of the analogues.
Migration of the cells could be inhibited by both compounds, but at different levels. Both produced abnormal types of cells, but not the same type of abnormality. Uptake of P32 was inhibited by both compounds. Addition of nicotinic acid failed to reverse the effects of the analogues at the concentrations used.
STUDIES ON A SARCOSINE OXIDASE OF BACTERIAL ORIGIN
Authors: Kopper Paul H. ,   With the Technical Assistance of Leon Robin
Published: May 2004

A "sarcosine oxidase" was prepared from a creatinine-decomposing strain of Pseudomonas aeruginosa.
The enzyme is inactivated by drying, lyophilization, and dialysis against distilled water. No dialyzable cofactor was found.
Optimal activity of the enzyme is reached at pH 7.8. Enzyme activity is directly proportional to enzyme concentration and also to substrate concentration up to the point of saturation of enzyme with substrate molecules. One molecule of enzyme combines with one molecule of substrate.
Data concerning the effect of temperature and of a variety of chemical compounds on the enzyme are presented.
Its inactivation by heat follows the course of a first order reaction, and the critical thermal increment between 48° and 52°C. was calculated to be 103,000 calories per mol. The relationship of enzyme concentration to heat inactivation rates is illustrated.
ENZYME KINETICS AND THE RATE OF BIOLOGICAL PROCESSES
Authors: Kavanau J. Lee 
Published: May 2004

It is found empirically that a simple modification of the usual theoretical kinetic formulation (in which a transformation in the temperature scale is made) describes the temperature dependence of a wide variety of biochemical processes with a greater accuracy than hitherto achieved. Used in conjunction with the formulation of the theory of absolute reaction rates this empirical relation facilitates the determination of the thermodynamic functions. The results of applying these relations to biochemical processes support the contention that in the lower temperature range of enzyme activity a thermodynamic equilibrium exists between catalytically active and inactive forms of the enzyme.
It is suggested that at low temperatures the formation of intramolecular hydrogen bridges converts reactive enzyme particles to a catalytically inactive condition, in which the active centers either lose their specific configuration or are no longer exposed to the substrate. Upon the basis of this interpretation, values of the entropy changes that are calculated theoretically are found to be in agreement with those calculated from the experimental data.
The reactive configuration of the enzyme is apparently possessed in only a relatively narrow temperature band, being lost at both high and low temperatures.
The kinetics of biological processes appear to differ only quantitatively from those of in vitro enzyme-catalyzed reactions. In both cases the non-linearity of the Arrhenius plots appears to be due to the fact that in the lower temperature range of enzyme activity a series of reactions are involved in the formation of the activated complex. These include reactions which lead to the formation of the catalytically reactive form of the enzyme followed by that which leads to the formation of the activated complex. The conversion of enzymes to the catalytically inactive form is essentially completed at temperatures of –10–0°C. in living systems, whereas in in vitro experiments with purified enzyme preparations this condition is not attained until temperatures 30–60°C. lower have been reached.
REGULATORY MECHANISMS OF CELLULAR RESPIRATION
Authors: Barron E. S. Guzman , Ardao Maria Isabel , Hearon Marion 
Published: May 2004

The rate of the aerobic metabolism of pyruvic acid by bakers' yeast cells is determined mainly by the amount of undissociated acid present. As a consequence, the greatest rate of oxidation was observed at pH 2.8. Oxidation, at a slow rate, started at pH 1.08; at pH 9.4 there was no oxidation at all. The anaerobic metabolism, only a fraction of the aerobic, was observed only in acid solutions. There was none at pH values higher than 3.
Pyruvic acid in the presence of oxygen was oxidized directly to acetic acid; in the absence of oxygen it was metabolized mainly by dismutation to lactic and acetic acids, and CO2. Acetic acid formation was demonstrated on oxidation of pyruvic acid at pH 1.91, and on addition of fluoroacetic acid. Succinic acid formation was shown by addition of malonic acid. These metabolic pathways in a cell so rich in carboxylase may be explained by the arrangement of enzymes within the cell, so that carboxylase is at the center, while pyruvic acid oxidase is located at the periphery.
Succinic and citric acids were oxidized only in acid solutions up to pH 4. Malic and α-ketoglutaric acids were not oxidized, undoubtedly because of lack of penetration.
DISTANT EFFECTS OF TOXIC AGENTS
Authors: Osterhout W. J. V. 
Published: May 2004

Toxic solutions applied at one end of a Nitella cell 6 cm. long may produce little or no visible change in the structure of the protoplasm at the place of application but if the opposite end is covered with water its protoplasm soon disintegrates. If the middle of the cell is covered with mineral oil this region remains normal in appearance for half an hour or more.
The result is due to the movement of substances in the cell. The loss of substances at the end where the toxic agent is applied results in loss at the opposite end if it is covered with water since water enters and travels along inside the cell carrying substances with it. This causes injury at the spot where the water enters.
The conception developed here differs fundamentally from the usual view that the effects of injury spread gradually from the region where the toxic agent is applied to the immediately adjoining regions and thence to more remote places.
The change produced by loss of substances produces an interesting pattern which deserves study.
THE MORTALITY OF BACTERIOPHAGE CONTAINING ASSIMILATED RADIOACTIVE PHOSPHORUS
Authors: Hershey A. D. , Kamen M. D. , Kennedy J. W. , Gest H. 
Published: May 2004

The bacteriophage T4 containing assimilated radioactive phosphorus is inactivated at a rate proportional to the specific radioactivity of the constituent phosphorus. The beta radiation from the phosphorus makes a negligible contribution to this effect. The inactivation is therefore a direct consequence of the nuclear reaction, which kills the phage with an efficiency of about 1/12. Several phages related to T4 behave similarly.
When radioactive phage is grown from a seed of non-radioactive phage, all of the phage progeny are subject to killing by radioactive decay.
The phage is killed by beta radiation from P32 with an efficiency of about 1/100 per ionization within the particle volume.
Bacteriophage T4 and its relatives contain about 500,000 atoms of phosphorus per infective particle. Virtually all this phosphorus is adsorbed to bacteria with the specificity characteristic of the infective particles, and none of it can be removed from the particles by the enzyme desoxyribonuclease. The phosphorus content per particle, together with the published data on analytical composition, indicates a particle diameter close to 110 mµ for the varieties of phage studied.
INJURY IN RELATION TO CELL ORGANIZATION
Authors: Osterhout W. J. V. 
Published: May 2004

When a part of a Nitella cell, A, is covered with water and the rest of the cell, B, is in contact with a toxic solution there is an escape of solutes at B. This is followed by the escape of solutes at A which causes the death of A. Water enters at A, flows along inside the cell, and escapes at B carrying solutes with it. When this is prevented by covering A with mineral oil the escape of solutes at A is delayed and the life of A is correspondingly prolonged. It is remarkable that this occurs in spite of the fact that the hydrostatic pressure inside the cell (turgor) drops from 6.4 atmospheres to zero.
It would seem that A might not be affected by the death of B if the escape of solutes could be prevented.
ON THE RELATION OF THE STRENGTH-FREQUENCY CURVE IN EXCITATION BY ALTERNATING CURRENT TO THE STRENGTH-DURATION AND LATENT ADDITION CURVES OF THE NERVE FIBER
Authors: Tasaki Ichiji , Sato Masayasu 
Published: May 2004

1. Determinations were done of the strength-duration, the strength-frequency, and the latent addition curves with single fiber preparations.
2. Calculation of the strength-duration and strength-frequency curves from the latent addition data by the Blair-Monnier-Hill-Rashevsky theory yielded results which showed a considerable divergence from the actual data. Calculation by the method of integrating the whole latent addition curve yielded satisfactory results.
3. The effects of electrotonus and the inactive tissues around the nerve fiber upon the strength-frequency relation were investigated.
4. It was suggested that, for alternating current stimuli and two-way condenser discharge stimuli of very high frequencies, threshold was lowered by the rectifying action of the plasma membrane.
STUDY OF SOME ENZYME SYSTEMS BY MEANS OF THE DIFFERENTIAL MICRORESPIROMETER
Authors: Entner Nathan , Kirk Paul L. 
Published: May 2004

Three enzymic phenomena, inactivation by oxygen, QOO2 measurements of a dehydrogenase system, and hydrolysis of acetyl phosphate by a phosphatase of Clostridium kluyveri, were studied by means of the differential microrespirometer.
Respiration of yeast cells was also measured with the same instrument.
All results obtained in the four types of study agreed closely with earlier results obtained with the Warburg apparatus. The amount of sample needed was of the order of 1/100 to 1/200 of that necessary for comparable study with the Warburg apparatus. The advantages of the instrument in enzyme isolation and purification studies are discussed.
THE REDUCTION OF FORMALDEHYDE BY BACTERIAL CELLS
Authors: Kopper Paul H. ,   With the Technical Assistance of Leon Robin
Published: May 2004

Formaldehyde is reduced to methyl alcohol by living cells of a creatinine-decomposing strain of Pseudomonas aeruginosa. The amount of HCHO taken up in 30 minutes by 3 x 1010 cells of this organism is termed its reducing capacity. It was found to be 400 to 480 µg.
The reaction takes place over wide pH and temperature ranges, is independent of the concentration of formaldehyde as long as the latter is not high enough to exert a toxic effect on the cell, but depends on the number of bacteria present.
In cultures, 3 to 7 days old, there is a decline in reducing capacity without a proportionate decrease in the number of viable cells. On the other hand in cultures, 2 to 4 weeks old, the number of viable cells determines the amount of HCHO taken up.
N/100 NaOH depresses the reducing capacity of the organism without affecting bacterial viability.
Exposure of bacterial suspensions to temperatures of 46–52°C. for 10 minutes causes a far more rapid decrease in the number of viable cells than in reducing capacity.
Incubation of cellular suspensions with nutrient substances, which are able to support adequately the growth of the organism, for 30 minutes prior to the addition of HCHO, induces increases in reducing capacity.
The uptake of HCHO by different microorganisms seems to be related to their gaseous and nutritional requirements. Strains of P. aeruginosa and P. fluorescens are predominantly aerobic, least fastidious in their nutritional requirements, most active against HCHO, and least susceptible to the action of aureomycin and chloromycetin.
The potential significance of cellular reducing capacity is discussed.
STUDIES ON ISOLATED CELL COMPONENTS
Authors: Anderson Norman G. , Wilbur Karl M. 
Published: May 2004

1. The addition of heparin to rat liver, kidney, or brain nuclei has been found to bring about the release of a gel. Chemical analysis and histochemical studies on whole homogenates and isolated nuclei demonstrated that the material released by heparin contained desoxyribonucleic acid (DNA) and protein. The action of heparin on nuclei is interpreted as the result of a combination with the basic proteins of the nucleus with a consequent displacement of DNA.
2. The addition of heparin to a finely divided dilute liver homogenate prepared in a phosphate-sucrose solution at pH 7.1 brings about a marked increase in viscosity which reaches a maximum in 6 to 8 minutes at 23° and then declines.
3. The concentration threshold for the viscosity effect was 0.1 mg. per 100 mg. fresh rat liver, with further increases in viscosity at higher heparin concentrations. Over a period of several hours a marked decrease in response to heparin was observed in homogenates stored at 0°.
4. Fractionation of the homogenate demonstrated that the viscosity increase was due to the presence of the nuclei alone, other components showing no effect. Microscopic observation showed that the increase in viscosity was associated with the appearance of a clear gel around nuclei treated with heparin.
5. Heparin brought about the release of DNA from the nuclei of incubated rat liver, kidney, and brain homogenates. In some instances over half the DNA is found in the supernatant after high speed centrifugation (20 minutes, 21,000 x g).
6. No correlation was found between anticoagulant activity of heparin preparations and their effectiveness in causing an increase in the viscosity of liver homogenates. Desulfated heparin produced none of the results described here for heparin.
TISSUE CULTURE MEDIA
Authors: Jacquez John A. , Barry Enid 
Published: May 2004

1. Human placental cord serum contains a factor or factors necessary for active growth of fibroblasts in tissue culture and a factor which prevents the appearance of a characteristic toxicity.
2. The growth-promoting factor(s) is stable to heating to 60°C. for 30 minutes and is associated with the euglobulin fraction of the serum.
3. Extraction of dried cord serum with benzene, chloroform, and ether does not cause any decrease in growth-promoting activity.
4. Sera from hypophysectomized, adrenalectomized, and thyroid-parathyroidectomized rats show as much growth-promoting activity as normal rat sera.
5. Bovine gamma globulins, anterior pituitary growth hormone, and insulin do not replace the serum growth factor.
6. The toxicity-preventing factor is serum albumin.
7. Evidence is presented that the toxicity is due to free fatty acids in the medium and that serum albumin acts by binding the fatty acids.
ENZYME SYSTEMS IN TETRAHYMENA GELEII S
Authors: Seaman Gerald R. 
Published: May 2004

The rates of activity of the dehydrogenase systems in Tetrahymena, which are concerned with carbohydrate oxidation, in descending order of activity are: lactic &gt; isocitric &gt; succinic = glucose &gt; glucose-6-phosphate = 6-phosphogluconic = malic &gt; glutamic = cytochrome linked α-glycerophosphate dehydrogenase.
No evidence was obtained to indicate the presence of DPN linked α-glycerophosphate dehydrogenase.