bluuebunny/crossref_metadata_2025_split huggingface dataset:
PROTEOLYTIC ENZYMES
Authors: Grob David 
Published: May 2004

1. The literature on conditions affecting the activity of proteolytic enzymes has been reviewed.
2. Experimental data on the control of the activity of trypsin, leucoprotease, papain, serum antiprotease, leucopeptidase, and pancreatic peptidase have been presented. These data indicate that:
(a) The polymorphonuclearleucocytes of the cat contain abundant proteinase and peptidase active at neutral pH; those of the rabbit lack proteinase active at neutral pH.
(b) Reducing agents, including several biologically important thiol-sulfhydryl compounds and ascorbic acid, inhibit the activity of leucoprotease and trypsin. For each reductant the degree of inhibition is proportional to the reducing capacity of the medium.
(c) p-Aminobenzoic acid, sulfonamides (especially sulfathiazole), and many diphenyl sulfones inhibit the activity of leucoprotease.
(d) Serum, plasma, several heavy metals, ammonium salts, asparagine, thiourea, heparin, glutamic acid, tyrothricin, calcium chloride, and bile salts and bile acids also inhibit the activity of leucoprotease, and in most cases of trypsin too.
(e) Preparations of tryptic digests of proteins, and egg white trypsin inhibitor, inhibit trypsin to a much greater degree than leucoprotease.
(f) Mild oxidizing agents increase the activity of leucoprotease and trypsin.
(g) Oxidizing agents and some inhibitors of sulfhydryl groups inhibit the antiproteolytic activity of the serum. It is suggested that serum antiprotease may consist (chiefly) of reducing agents, including thiol-sulfhydryl peptides which exert their antiproteolytic activity by virtue of the presence of sulfhydryl groups.
(h) The antiproteolytic activity of the serum is progressively weakened by exposure to a hydrogen ion concentration below pH 6.5 or above pH 9.7. Because of this the pH optima of leucoprotease and trypsin are shifted in the presence of serum from pH of 7 and 8 to pH of 6 to 6.5, and the range of activity of these enzymes is slightly widened, in both acid and alkaline reactions.
(i) Reducing agents increase the activity of leucopeptidase and pancreatic peptidase. Serum, sulfathiazole, and thiourea have little or no effect.
3. The significance of the oxidation-reduction system in the control of the activity of leucoprotease, trypsin, serum antiprotease, leucopeptidase, and pancreatic peptidase has been emphasized.
PROTEOLYTIC ENZYMES
Authors: Grob David 
Published: May 2004

It has been suggested that the ability to control the activity of leucoprotease and serum antiprotease may prove useful in the further study and understanding of such phenomena as: (1) inflammation; (2) the resolution of inflammatory exudates and the absorption of absorbable foreign bodies; (3) the protection of joint and other structures from the proteolytic action of leucoprotease; (4) the neutralization of the destructive protease liberated in acute pancreatitis and from duodenal fistulae; (5) experimental arteriosclerosis and arteriolonecrosis; (6) the coagulation of the blood; (7) the possibility of prolonging the action of insulin; (8) the release of thyroglobulin by the thyroid gland; (9) bacterial growth and sulfonamide action.
In this last respect evidence has been presented that the products of the hydrolysis of protein by leucoprotease stimulate bacterial growth and directly and indirectly inhibit sulfonamide action, and the hope has been expressed that the ability to control leucoprotease action may contribute to the more successful use of chemotherapeutic agents in purulent lesions.
THE CHEMISTRY OF DAYLIGHT VISION
Authors: Bliss Alfred Frederick 
Published: May 2004

1. While several reports of photosensitive pigments from the retinas of animals possessing large numbers of cone cells have been published, the only study which could be confirmed was Wald's discovery of iodopsin, a red-sensitive pigment from chicken eyes.
2. In its chemical properties, such as the range of pH stability and the effect of polar organic solvents, iodopsin resembles rhodopsin but is considerably more labile.
3. A partial purification from inert yellow impurities has been effected by prehardening the retinas in pH 4.9 acetate buffer before extraction by 2 per cent digitonin. Rhodopsin was an inevitable contaminant in most methods of extraction, but could be reduced to about 10 per cent of the absorption due to iodopsin by extraction of unhardened retinas with 4 per cent Merck's saponin in ¾ saturated magnesium sulfate for about 1 hour.
4. The rate of bleaching of iodopsin was found to be first order and linear with respect to energy.
5. The bleaching effectiveness spectrum of iodopsin was determined with the aid of color filters of known energy transmission, and shows a maximum at 560 mµ in the yellow green with a lower plateau in the blue. The spectrum is in good agreement with the sensitivity of the human cones except for the wavelength of maximum bleaching effectiveness. The maximum sensitivity of the human cones is found at 540 mµ.
6. Previous reports of changes in pH and inorganic phosphate level of retinas due to bleaching could not be confirmed.
THE POTENTIOMETRIC ANALYSIS OF MEMBRANE STRUCTURE AND ITS APPLICATION TO LIVING ANIMAL MEMBRANES
Authors: Meyer Kurt H. , Bernfeld P. 
Published: May 2004

1. The electromotive forces which arise, if two electrolyte solutions are separated from each other by a layer of any kind, are discussed. A general equation is derived comprising the known equations for diffusion, partition, and membrane (Donnan) potentials as special cases.
2. A method is proposed to analyse membranes potentiometrically with respect to their cation or anion selectivity, their dissolving power for ions, and their influence on ion mobility (migration velocity).
3. The possibility of analysing a membrane composed of several layers of different permeability is discussed.
4. The investigation of the skin of the belly of Rana temporaria leads to the following results. It is composed of at least four layers of different permeability, one of which is specifically permeable to H ions and is very likely identical with the "basal membrane" situated between the stratum germinativum and the corium. The major part of the resting potential of the skin is located across this membrane and is due to the difference of H+ concentrations on both sides of the membrane.
5. Experiments on muscle show that the sarcolemma is specifically permeable to H ions. The injury potential of the muscle is attributed to the difference of H+ concentration inside and outside the fibre.
HEMOLYTIC SYSTEMS CONTAINING ANIONIC DETERGENTS
Authors: Ponder Eric 
Published: May 2004

1. The members of the homologous series of anionic detergents, the sodium salts of the sulfated straight chain alcohols with the general formula CnH2n+1·SO3·Na, are hemolytic, the lytic activity being at a maximum when the compound contains 14 carbon atoms in the chain. In systems in which lysis is comparatively rapid, the hemolytic effect increases with increasing pH, but in systems containing quantities of lysin near the asymptotic concentrations the pH dependence of the activity is reversed. The effect of temperature is principally one on the velocity constant of the lytic reaction, with smaller effects on the position of the asymptotes of the time-dilution curves and on their shape.
2. The quantities of the detergents which produce disk-sphere transformations are approximately one-tenth of those required to produce complete hemolysis. In most cases, the shape change occurs when there are too few detergent molecules present to cover the red cell surfaces with a monolayer.
3. Plasma inhibits the hemolytic action of these detergents, and, in the quantities in which they occur in plasma, lecithin, serum globulin, cholesterol, and serum albumin, produce inhibitory effects which increase in that order in systems containing the C-14 sulfate. It can be inferred from these inhibitory effects that the anionic detergents can form compounds or complexes with lipid, lipoprotein, and protein components of the red cell ultrastructure.
CRYSTALLIZATION OF PEPSIN FROM ALCOHOL
Authors: Northrop John H. 
Published: May 2004

1. Pepsin is soluble in 65 per cent alcohol and may be readily crystallized from 20 per cent alcohol. The crystals appear as needles or plates which may be transformed into the usual hexagonal bipyramids by recrystallization from water. The different crystals are probably two crystalline forms of the same chemical substance.
2. The enzyme is quite stable in 20 per cent alcohol at pH 2.0 but is inactivated by high concentrations of alcohol.
3. The enzyme is stable for several hours in 65 per cent alcohol at pH 4.0 to 5.0 but is rapidly inactivated in more acid solution.
4. No increase in activity could be noted after treatment with hydrogen peroxide.
5. No proteolytic activity either before or after treatment with hydrogen peroxide could be found in trichloracetic acid filtrates, butyl alcohol extracts of pepsin preparations, or oxidized phenylhydrazine solutions.
REACTION OF ENZYMES AND PROTEINS WITH MUSTARD GAS (BIS(ß-CHLOROETHYL)SULFIDE)
Authors: Herriott Roger M. , Anson M. L. , Northrop John H. 
Published: May 2004

1. The rate of reaction of mustard gas (H) with thirteen proteins has been determined. The extreme variation in reaction rates is about 100:1.
2. No qualitative difference in the results was observed when the treatment with H was carried out by the Dixon or stirring methods.
3. The kinetics have been analyzed and a bimolecular equation derived which fits the facts.
4. The carboxyl groups of all proteins reacted when the reaction with H was carried out at pH 6.0 in M/25 acetate buffer. In most cases the number of carboxyl groups covered was approximately equal to the number of H residues bound.
5. The amino groups of proteins failed to react with the possible exception of yeast hexokinase.
6. The color obtained when proteins were mixed with Folin's phenol reagent at pH 8.0 decreased as the protein was treated with H. The color returned on treatment of the H-protein with alkali and many of the combined H groups were hydrolyzed. Similar results were observed when a concentrated glycyltyrosine solution was treated with H.
THE RELATIONSHIP BETWEEN CHEMICAL STRUCTURE AND THE RESPONSE OF BLOWFLIES TO TARSAL STIMULATION BY ALIPHATIC ACIDS
Authors: Chadwick L. E. , Dethier V. G. 
Published: May 2004

Using the technique of proboscis extension in antennectomized-labellectomized flies, the rejection thresholds of Phormia regina for 18 fatty acids and one mineral acid have been determined.
The conclusions reached on the basis of these data may be summarized in the following terms:
Tarsal stimulation by acids involves the summation of components from at least two sources. Of these the hydrogen ion is the most important. The other major factor is probably the anion rather than the undissociated acid. The stimulating power of the anions (or free acid molecules) increases with increasing chain length in both the mono- and dicarboxylic series, but the rate of increase decreases as the series is ascended. Acids containing 6 or more carbon atoms are not sufficiently soluble in 0.1 M sucrose to reach the threshold of rejection. Substitution of —H in the acyl grouping by —Cl, —OH, =O or —COOH, the presence of a C=C bond, or a shift from the trans- to the cis- configuration all diminish the effectiveness of the anion (or free acid). But since such alterations also augment the degree of dissociation and consequently the concentration of hydrogen ions, the net result is ordinarily a lowering of threshold in terms of the molar concentration required for rejection.
THE EFFECTS OF SULFATHIAZOLE AND OF PROPYL CARBAMATE ON THE RATE OF OXYGEN CONSUMPTION AND GROWTH IN ESCHERICHIA COLI
Authors: Fisher Kenneth C. , Armstrong Florence H. 
Published: May 2004

1. The rates of growth and of oxygen consumption by cells of E. coli have been measured under identical conditions, and the effects of sulfathiazole (ST) and of n-propyl carbamate (PC) on these two processes have been compared.
2. The rate of growth was measured by (a) the increase in the viable cell count, (b) the increase in the optical density of the culture, (c) the increase in the rate of oxygen consumption, and (d) the decrease in the ammonia of the medium. The results as indicated by these several measures were identical under the conditions of these experiments.
3. Concentrations of ST or of PC which are just sufficient to stop growth completely, lower the rate of oxygen consumption per unit of bacterial protoplasm to a value approximately 50 per cent of that seen in the absence of the inhibitor.
4. It is shown that the rate of oxygen consumption in cells from old cultures is less affected by ST than is the rate of oxygen consumption by cells from young cultures. It is probable that the rate of oxygen consumption by "old" cells is lower than that of "young" cells.
5. The effects of ST and PC on both the rate of oxygen consumption and the rate of growth are very similar, indicating in a general way, that the mechanism of the actions of these two inhibitors is similar. Furthermore, since both of them produce appreciable inhibition of the rate of oxygen consumption while they are inhibiting growth, the possibility that the effect on oxygen consumption is the immediate cause of the effect on growth must be entertained.
K-Na EXCHANGE ACCOMPANYING THE PROLYTIC LOSS OF K FROM HUMAN RED CELLS
Authors: Ponder Eric 
Published: May 2004

In systems containing human red cells and sodium taurocholate as a lysin, or distearyl lecithin as a sphering agent, the prolytic loss of K at 25°C. is accompanied by a gain of Na by the cell, the gain being somewhat greater than the K loss. A small volume increase accompanies the exchange. The kinetics of the K loss and the Na gain are similar to those already described; i.e., the changes are rapid at first, and slow down so that after 12 to 20 hours it appears that a new steady state is being approached.
Similar, but smaller, losses of K and gains of Na occur when the cells stand in isotonic NaCl at 25°C. without the addition of a lysin or sphering agent.
On these and other experimental grounds, it is impossible to retain the idea that the mammalian red cell in general is impermeable to cations. The cells nevertheless seem to be in a steady state with respect to their environment, their ionic composition changing as the composition of the environment is changed. The possible processes by means of which one steady state can be exchanged for another—changes in the permeability of a surface membrane, changes in the velocity of an active ion transfer process dependent on red cell metabolism, and changes in the activity of the ions in the red cell interior as a result of changes in an orderly internal structure—are discussed.
A STUDY OF THE ADENOSINE TRIPHOSPHATASE ACTIVITY OF MYOSIN AND ACTOMYOSIN
Authors: Mommaerts W. F. H. M. , Seraidarian Krikor 
Published: May 2004

1. An experimental study was made on the adenosine triphosphatase action of crystalline myosin and actomyosin preparations under different conditions.
2. No enzymatic activity was found in the absence of salts. Activation was given by KCl and CaCl2, whereas MgCl2 in the presence of other ions inhibited.
3. The effect of pH is complex. In stabilizing buffers or at low temperature, there are two optima (pH 6.2 to 6.5 and pH 9.2) provided Ca is present. Without Ca only the acid optimum is found. The highest activities are reached in glycine buffer at pH 9.2 in the presence of Ca.
4. The study of the Mg-Ca antagonism revealed that the inhibition due to Mg is fully developed with Mg:Ca ratios less than 1, the inhibition usually exceeding 90 per cent.
5. It is shown that in the muscle the myosin-ATPase is most probably also subjected to the inhibitory action of the Mg ions.
6. From data in the literature it is calculated that the liberation of inorganic phosphate during muscular activity takes place at a rate of at least 0.200 mg. P per mg. myosin per minute.
7. From the results of the present study it is found that the myosin in the muscle can liberate inorganic phosphate from ATP at a rate of at most 0.003 mg. P per mg. myosin per minute.
8. It is concluded therefore that myosin-ATPase cannot be responsible for the liberation of the main part of the phosphate in contracting muscle, and therefore cannot have the rôle in muscular metabolism ascribed to it in recent hypotheses and discussions.
SOLUBILITY OF MUSTARD GAS [BIS (ß-CHLOROETHYL) SULFIDE] IN WATER, MOLAR SODIUM CHLORIDE, AND IN SOLUTIONS OF DETERGENTS
Authors: Herriott Roger M. 
Published: May 2004

1. The solubility of mustard (H) in water and in molar sodium chloride was found to be 5.8 x 10–3 molar and 3.2 x 10–3 molar respectively or 0.92 mg. per ml. and 0.5 mg. per ml. Solubility curves have been drawn and the usefulness of this method in examining the homogeneity of H preparations as well as in establishing their solubility, is discussed.
2. Certain detergents increase the solubility of H in water. The solubility was found to increase with the concentration of detergent.
3. Many detergents were found to affect the interfacial tension between H and water so that with slight agitation liquid H breaks up into minute droplets. This in turn greatly accelerates the rate of solution.
DETECTION OF MUSTARD GAS (H), LEWISITE (L), ETHYLDICHLORARSINE (ED), AND PHENYLDICHLORARSINE (PD) WITH TRAINED DOGS OR RATS
Authors: Northrop John H. 
Published: May 2004

Dogs and rats may be trained to detect very low concentrations of mustard gas (0.1 gamma per liter of air) by shocking the animals with an induction coil when they touch meat which has been exposed to the gas.
Animals trained in this way will refuse meat which is contaminated with the gas.
COLORBLIND VISION
Authors: Hecht Selig , Hsia Yun 
Published: May 2004

1. Measurements have been made of the dark-adapted foveal threshold of normal and colorblind persons in five parts of the spectrum using a 1° circular test field.
2. Compared to normals, protanopes (red-blinds) show an elevation of the threshold which increases slowly from blue to yellow and rises rapidly thereafter until in the red the threshold is more than ten times as high as normal. Deuteranopes (green-blinds) do not show so high an elevation, their maximum in the green being only about 70 per cent above normal.
3. These threshold elevations correspond to luminosity losses in the spectrum. For the protanope the total loss in the spectrum is nearly one-half of the normal luminosity; for the deuteranope it is nearly two-fifths of normal.
4. Such losses support the idea that colorblindness corresponds to the loss of one of the three receptor systems usually postulated to account for normal color vision. However, the color sensations reported by colorblind persons, especially monocular colorblinds, do not support the idea of a lost or inactivated receptor system. A fresh explanation for colorblindness is called for to reconcile these conflicting kinds of evidence.
THE OXYGEN CONSUMPTION OF THE MICROSPORES OF TRILLIUM IN RELATION TO THE MITOTIC CYCLE
Authors: Stern Herbert , Kirk Paul L. 
Published: May 2004

The oxygen consumption of 265 single Trillium erectum anthers was measured before and during the mitotic cycle of the microspores using a modified differential microrespirometer.
The results show a rising oxygen consumption of the anther in the premitotic stages followed by a sharp drop immediately preceding and during active division. It is suggested from these results that active division may be associated with anaerobic behavior and that the rapid uptake of molecular oxygen commonly associated with proliferating tissues is probably characteristic of premitotic development.
THE QUANTIC AND STATISTICAL BASES OF VISUAL EXCITATION
Authors: Baumgardt Ernest L. M. 
Published: May 2004

1. The photochemical theories of vision cannot provide a valid interpretation of the facts over the whole range of brightness. The fact that liminal excitation is increased by the absorption of a very small number of quanta, each absorbing rod receiving a single quantum, excludes the intervention of the mass action law which is the basis of all photochemical theories.
2. Owing to the quantic structure of light and to the random distribution of quanta in a faint light pencil, there must exist numerical relations between the threshold energy on the one hand and the size of the retinal area stimulated and the stimulation time on the other, whatever may be the inner mechanism of liminal excitation. When taking as a basis Van der Velden's experimental results, viz. that two quanta absorbed during a certain interval of time are sufficient to raise threshold excitation, the probability calculus enables us to compute the course of threshold energy in relation to the stimulation time and to the stimulated retinal area. No arbitrary parameter is needed to do so; the only constant to be used is found by experiment.
3. The quantic and statistical theory of visual excitation that we put forward in the present paper enables us to predict the validity of Ricco's law within what we call a "quasi-independent unit" and the validity of Piper's law within a test area made up of a certain number of such units. This theory does not correspond exactly with Piéron's law for foveal threshold in relation to the size of the stimulated area, but the deviation is probably due to an artefact; viz., the action of the micronystagmus.
4. Experiment proves that in region IV of the retina, 15° temporally from the fovea of the right eye of two observers, Ricco's law applies strictly in rod vision from 2'12'' to 31'36'' and, perhaps, further on.
5. In the same region, from 12'30'' to 31'36'', Piper's law applies strictly in cone vision of extremely red light.
6. In peripheral vision with extremely red light the photochromatic interval has been found to be null.
7. Our theoretical interpretation of the term "quasi-independent unit" fits well with the histological data of the retina.
8. Numerical deviations of the theoretic time law of threshold intensity from the empirical course may be due to the existence of a relative refractory period of the ganglion (or bipolar) cells. This mechanism would be a sort of instantaneous adaptation of nervous elements and would explain the fact that the sensation level increases very much slower than the brightness level, in a range of the brightness scale where the photochemical adaptation cannot account for this phenomenon.