bluuebunny/crossref_metadata_2025 huggingface dataset:
IMMUNOLOGICAL STUDIES OF INSECT METAMORPHOSIS
Authors: Telfer William H.
Published: May 2004

1. In the pupal stage of the cecropia silkworm, antigen 7, a protein with the solubility characteristics of an albumin, is present in female blood in approximately a thousand times higher concentration than in the blood of males. Antigen 7 is undetectable in the blood of larvae of either sex. It first appears in the blood after the larva has spun its cocoon, and is present throughout all subsequent stages of metamorphosis. Late in the pupal-adult transformation, when the eggs are produced, the concentration of antigen 7 in female blood decreases significantly.

2. An antigen which could not be distinguished from antigen 7 immunologically is present in solution in the yolk of unfertilized eggs.

3. In females which, by ovariectomy, were prevented from forming eggs, the concentration of antigen 7 in the blood increased during the usual period of egg formation rather than undergoing the normal decrease. Ovaries transferred to the hemocoel of males produced eggs but were unable to incorporate antigen 7 in the yolk unless a detectable amount of the protein was present in the blood. The ovaries of polyphemus females which had been transfused with cecropia blood incorporated cecropia antigen 7 into the eggs they produced. These lines of evidence indicate that antigen 7 is secreted into the blood by some tissue other than the ovaries, and that it is subsequently drawn from the blood and deposited in the yolk.

4. The concentration of antigen 7 in the clear, liquid fraction of the yolk is four times higher than the maximum concentration attained in the blood during metamorphosis, and twenty times higher than that of the blood at the conclusion of egg formation. The protein thus appears to be transferred from blood to yolk against a concentration gradient.
EFFECTS OF CORTISONE ON REGENERATING RAT LIVER
Authors: Einhorn Stanley L. , Hirschberg Erich , Gellhorn Alfred
Published: May 2004

The effects of continuous administration of cortisone on the metabolism of regenerating rat liver have been studied. Whereas the restoration of the weight of the liver after partial hepatectomy was not markedly affected by cortisone, the multiplication of cells was reduced to a significant degree after the first 2 days of regeneration. Liver restoration in terms of nucleic acids was similarly inhibited by cortisone. The results are consistent with the interpretation that the inhibition of cell multiplication in this system is dependent on and keeps pace with the inhibition of nucleic acid synthesis by this drug. At almost any time after hepatectomy, the nucleic acid content of the liver cells was the same in treated and in untreated animals.

In ancillary studies, it was shown that cortisone caused the cells of regenerating liver to be increased in size and weight through the increased infiltration of lipids. Changes in water, protein, and carbohydrate content of the liver cells did not contribute to this increase in the weight of the cells.

Since all animals were treated with cortisone for 5 days before hepatectomy, data were also obtained on the effect of this agent on the resting liver. This course of treatment brought about a significant decrease in the number of cells per unit wet weight and in the water content of the livers. The nucleic acid content of the cells at hepatectomy, on the other hand, was unchanged.
PHOTOSYNTHESIS BY PROTOPLASM EXTRUDED FROM CHARA AND NITELLA
Authors: Tolbert N. E. , Zill L. P.
Published: May 2004

(a) Photosynthesis with protoplasm isolated from Chara or Nitella as measured by C14 fixation has been obtained at a rate 12 to 15 per cent of that of the whole cells.

(b) Photosynthesis by cut cells of Chara or Nitella with the vacuolar sap removed was at a rate comparable to that of the whole cells.

(c) Both the protoplasm and the cut cells reduced CO2 in the light to sucrose and hexose phosphates. Other products formed were also detected by paper chromatography. In contrast, dark controls fixed the C14 into products associated with plant respiration.

(d) An important difference in the products from the extruded protoplasm was the absence of C14-labelled pentoses or sedoheptulose which were formed, however, by the whole or cut cells. This suggests that the most sensitive site affected by disruption of the cells may be the steps involved in the regeneration of the "C-2 acceptor" for CO2 fixation in photosynthesis.
THE EFFECT OF ACTH AND ADRENAL STEROIDS ON K TRANSPORT IN HUMAN ERYTHROCYTES
Authors: Streeten D. H. P. , Solomon A. K.
Published: May 2004

The effect of ACTH and adrenal steroids on K transport in human erythrocytes has been studied. A new method of calculation has revealed that in normal human erythrocytes the K transport is not independent of external K concentration as had previously been thought. The equation describing the relationship is,

K influx (m.eq./liter cells hour) = [K]pi/(0.697 + 0.329 [K]pi)

in which [K]pi refers to the plasma K concentration at the beginning of the experiment. At the physiological plasma K concentration of 4.65 m.eq./liter, K influx is 2.09 m.eq./liter cells hour; K efflux is 1.95 m.eq./liter cells hour and is independent of plasma K concentration.

The effect of the infusion of ACTH and adrenal steroids on the K content of the erythrocytes was also studied. Infusions of ACTH or cortisone do not cause the expected loss in erythrocyte K content and may well cause a gain.

Infusions of ACTH and cortisone decrease the rate of K influx and efflux slightly at all stages of the infusion, as measured in vitro in blood samples drawn at various times during and following the infusion. However, the erythrocytes incubated in vitro do not exhibit the same changes in K content as are found in vivo. Hydrocortisone added to normal cells in vitro also decreases both influx and efflux of K, without affecting the K content of the cells.
MEMBRANE POTENTIALS IN THE DONNAN EQUILIBRIUM. II
Authors: Hitchcock David I.
Published: May 2004

Measurements were made of electromotive force in the Donnan equilibrium of systems containing dilute solutions of protein and acid. Removal of the membrane produced a decrease of no more than 2 to 4 mv. in electromotive force, while the membrane potentials, as estimated by the usual arbitrary assumption, were of the order of 12 to 34 mv. Ion ratios, as calculated from analyses for total chloride, were definitely greater than those calculated from the electromotive force of cells with salt bridges, as if there had been combination of some of the chloride ion with protein.
THE EFFECT OF FORMALDEHYDE ON THE OXYGEN EQUILIBRIUM OF HEMOGLOBIN
Authors: Guthe Karl F.
Published: May 2004

1. When formaldehyde (0.10 M) is added to solutions of human hemoglobin, the oxygen affinity of the hemoglobin increases considerably (more than tenfold near pH 7). The interaction between hemes of the same hemoglobin molecule decreases, as shown by a drop in the value of n in Hill's equation from 2.9 to 1.5 or less.

2. In the presence of formaldehyde, both n and the oxygen pressure for half-saturation fall gradually as the pH rises in the range from pH 6.2 to 7.2.

3. Some of the effect of formaldehyde on the oxygen equilibrium may be due to combination with sulfhydryl groups of the protein, but nitrogenous groups are probably also involved.
ELECTRICAL STUDIES ON THE COMPOUND EYE OF LIGIA OCCIDENTALIS DANA (CRUSTACEA: ISOPODA)
Authors: Ruck Philip , Jahn Theodore L.
Published: May 2004

The ERG of the compound eye in freshly collected Ligia occidentalis, in response to high intensity light flashes of ⅛ second or longer duration, begins with a negative on-effect quickly followed by an early positive deflection, rapidly returns to the baseline during illumination, and ends with a positive off-effect. As the stimulus intensity is decreased the early positivity progressively decreases and the rapid return to the baseline is replaced by a slowing decline of the negative on-effect. Responses were recorded with one active electrode subcorneally situated in the illuminated eye, the reference electrode in the dark eye.

The dark-adapted eye shows a facilitation of the amplitude and rates of rise and fall of the on-effect to a brief, high intensity light stimulus. This facilitation may persist for more than 2 minutes.

Following light adaptation under conditions in which the human eye loses sensitivity by a factor of almost 40,000 the Ligia eye loses sensitivity by a factor of only 3.

The flicker fusion frequency of the ERG may be as high as 120/second with a corneal illumination of 15,000 foot-candles.

Bleeding an otherwise intact animal very rapidly results in a decline of amplitude, change of wave form, and loss of facilitation in the ERG.

When the eye is deganglionated without bleeding the animal the isolated retina responds in the same manner as the intact eye.

Histological examination of the Ligia receptor layer showed that each ommatidium contains three different retinula cell types, each of which may be responsible for a different aspect of the ERG.
RELATION OF FUNCTION TO DIAMETER IN AFFERENT FIBERS OF MUSCLE NERVES
Authors: Hunt Carlton C.
Published: May 2004

1. A method of isolation of individual afferent fibers from muscle has yielded a representative sample of the fibers which comprise groups 1 (12 to 20 µ) and II (4 to 12 µ) of the afferent fiber diameter distribution of muscle nerves in cat.

2. Afferent fibers from muscle stretch receptors account for groups I and II of the afferent diameter spectrum of muscle nerves to soleus and medial gastrocnemius. Fibers from tendon organs are largely confined to the diameter range above 12 µ. This fiber group, which has a simple one-peak diameter distribution, is termed group IB. Fibers from muscle spindles show a bimodal diameter distribution and account for the remainder of fibers in the 12 to 20 µ group (termed IA) and substantially all of group II (4 to 12 µ).

3. No significant difference has been found in the receptor characteristics of the large (group IA) and intermediate sized (group II) spindle afferent fibers other than a slightly higher threshold of the latter to steady external stretch.
THE BEHAVIOR OF ISOLATED HEARTS OF THE GRASSHOPPER, CHORTOPHAGA VIRIDIFASCIATA, AND THE MOTH, SAMIA WALKERI, IN SOLUTIONS WITH DIFFERENT CONCENTRATIONS OF SODIUM, POTASSIUM, CALCIUM, AND MAGNESIUM
Authors: Barsa Mary C.
Published: May 2004

1. The blood of Chortophaga viridifasciata was analyzed. The average concentrations of inorganic cations expressed as milligrams per cent are: sodium, 250.66; potassium, 13.52; calcium, 11.40; and magnesium, 51.15. The osmotic pressure of the blood at 0°C. is 10.7 atmospheres. Protein and non-protein nitrogen, expressed as milligrams per cent, are 253.4 and 140.0, respectively.

2. The blood of Samia walkeri has an osmotic pressure of 13.36 atmospheres at 0°C. Its protein nitrogen is 628.58, and its non-protein nitrogen, 441.20 milligrams per cent.

3. The effects of isotonic chloride solutions of sodium, potassium, calcium, and magnesium and of distilled water on the heart beat of these two species were determined. The heart of the grasshopper failed to beat in isotonic solutions of KCl, MgCl2, or in distilled water. For both insects, sodium was found to be the least toxic ion. In the case of the grasshopper, calcium ranks next in order. In the case of the moth, potassium ranks next after sodium and is followed by calcium and magnesium.

4. The ratio of sodium to potassium in milligrams per cent, necessary for maintaining the normal heart beat of Chortophaga viridifasciata is 3 to 1, but it may be increased to at least 34 to 1 without any appreciable effects. The ratio of potassium to calcium necessary for maintaining the normal heart beat of this insect is 1 to 1, and may be increased to as much as 3 to 1.

5. The ratio of sodium to potassium, in milligrams per cent, necessary for maintaining the normal heart beat of Samia walkeri was found to be equal to or to exceed 1 to 13.8. The sodium content may be increased so that the ratio of sodium to potassium is 34 to 1 without any toxic effects. The ratios of potassium to calcium required for normal heart beat in this insect may be 1 to 1, 2 to 1, or 3 to 1.

6. The hearts of the grasshoppers beat normally in isotonic solutions having an osmotic pressure of 10.7 atmospheres. They beat equally well in solutions having an osmotic pressure of 13.4 atmospheres. The hearts of the cynthia pupae beat normally in isotonic solutions having an osmotic pressure of 13.36 atmospheres. However, they also beat normally in solutions having an osmotic pressure of 10.02 atmospheres. Therefore, although the blood of the cynthia moth and of the grasshopper have different osmotic pressures, their hearts are tolerant to solutions having the same tonicity. Because of this, and since the ratios of potassium to calcium necessary for maintaining normal heart beats of both insects are the same, solutions favorable to the grasshopper may also be favorable to the cynthia moth.
RELAXATION IN EXTRACTED MUSCLE FIBERS
Authors: Bozler Emil
Published: May 2004

1. Ethylenediamine tetraacetic acid (EDTA) in low concentrations imitates all the known effects of the relaxation factor ("Marsh factor"). In extracted muscle fibers which have contracted in a solution containing adenosinetriphosphate (ATP), the addition of EBTA causes relaxation, the subsequent addition of CaCl2, contraction.

2. In fibers which have been briefly immersed in 5 MM EDTA, ATP causes rapid relaxation if Mg is also present. These fibers have essentially the same properties as briefly extracted fibers. Brief immersion into a solution containing CaCl2 restores at once the original condition. It is concluded that EDTA produces its action by firmly combining with bound Ca, thereby inactivating it.

3. In relaxed muscle fibers not only Ca, but also lowering the concentration of Mg below a critical level, causes contraction. In such fibers Mg in the lowest effective concentrations increases contraction, but the effect reverses above a certain concentration.

4. At 0° Mg in the presence of ATP has a relaxing effect without the relaxation factor.

5. The results indicate that Mg has two distinct effects in the presence of ATP. It causes contraction at low concentrations, but above a critical concentration its relaxing action prevails. The last of these effects is blocked by bound Ca. If the latter is inactivated by EDTA, Mg in sufficiently high concentrations causes relaxation. The action of the relaxation factor can similarly be explained by assuming that it acts as a complexing agent which inactivates bound Ca.

6. Previous evidence that the relaxed state depends on the formation of an enzymatically inactive ATP-protein complex was confirmed. It was found that PP in low concentrations strongly increases the relaxing effect of ATP in briefly extracted fibers.
CHARACTERISTICS OF A NEW VIBRIO-BACTERIOPHAGE SYSTEM
Authors: Smith Lucile Schultz , Krueger Albert Paul
Published: May 2004

A vibrio-bacteriophage system isolated from San Francisco Bay mud is described. The vibrio lyses readily in distilled water and appears to be a new species. In contact with the phage it becomes lysogenic and forms large clumps. The phage presents no unique features.
ENZYMATIC BREAKDOWN OF THREONINE BY THREONINE ALDOLASE
Authors: Lin Shih-Chia C. , Greenberg David M.
Published: May 2004

1. The enzyme which splits threonine to acetaldehyde and glycine has been partially purified from rat liver (five- to sixfold purification) and the name threonine aldolase proposed for it.

2. The general properties of threonine aldolase have been studied. The enzyme is unstable to a pH below 5. The pH optimum of the enzyme reaction is at 7.5–7.7. The initial rate of production of acetaldehyde is proportional to the enzyme concentration, and when the enzyme concentration is constant, the production of acetaldehyde is proportional to the time, provided that the substrate is in excess. The enzyme is inhibited by the carbonyl group reagent, hydroxylamine. Attempts to demonstrate that pyridoxal phosphate is a cofactor were unsuccessful.

3. The enzyme splits only L-allothreonine and L-threonine and is inactive against the D-forms of these amino acids.

4. The enzyme reaction on DL-allothreonine follows first order kinetics. From the first order velocity constants and the initial rates of the rates of the reaction at various substrate concentrations the Michaelis constant, Ks, for this substrate has been evaluated. Michaelis constants have also been determined for threonine.

5. The optimum temperature for the enzymatic breakdown of DL-allothreonine at pH 7.65 was found to be 50°C. in phosphate buffer and 48°C. in tris-maleate buffer. The rate of thermal inactivation of the enzyme threonine aldolase obeys a first order reaction. The heat of thermal inactivation was calculated by the aid of the van't Hoff-Arrhenius equation to be 43,000 cal. per mole for the temperature range 41.2–46.6°C.

6. Equivalent amounts of acetaldehyde and glycine were formed from DL-allothreonine and the enzymatic breakdown of DL-allothreonine was found to be irreversible.
BIOELECTRIC EFFECTS OF IONS MICROINJECTED INTO THE GIANT AXON OF LOLIGO
Authors: Grundfest Harry , Kao C. Y. , Altamirano Mario
Published: May 2004

1. A technique is described for recording the bioelectric activity of the squid giant axon during and following alteration of the internal axonal composition with respect to ions or other substances.

2. Experimental evidence indicates that the technique as described is capable of measuring changes in local bioelectric activity with an accuracy of 10 to 15 per cent or higher.

3. Alterations of the internal K+ or Cl- concentrations do not cause the change in resting potential expected on the basis of a Donnan mechanism.

4. The general effect of microinjection of K+ Rb+, Na+, Li+, Ba++, Ca++, Mg++, or Sr++ is to cause decrease in spike amplitude, followed by propagation block.

5. The resting potential decreases when the amplitude of the spike becomes low and block is incipient.

6. The decrease in resting potential and spike amplitude may be confined to the immediate vicinity of the injection.

7. At block, the resting potential decreases up to 50 per cent, but injection of small quantities of divalent cations may cause much larger localized depolarization.

8. The blocking effectiveness of K+, Na+, and Ca++ expressed as reciprocals of the relative amounts needed to cause block is approximately 1:5:100. Rb+ has the same low effectiveness as does K+. Li+ resembles Na+. Ba++ and Mg++ are approximately as effective as Ca++.

9. Microinjection of Na+ may cause marked prolongation of the spike at the injection site as well as decrease in its amplitude.

10. The anions used (Cl-, HCO3-, NO3-, SO4-, aspartate, and glutamate) do not seem to exert specific effects.

11. A tentative explanation is offered for the insensitivity of the resting potential to changes in the axonal ionic composition.

12. New data are presented on the range of variation, in a large sample, of the magnitude of the resting potential and spike amplitude.
THE EFFECT OF NUTRITIONAL STATE ON PHOTOREVERSAL OF ULTRAVIOLET INJURIES IN DIDINIUM NASUTUM
Authors: Brandt C. L. , Shepard D. C. , Giese A. C.
Published: May 2004

1. The effect of the nutritional state of Didinium nasutum on its resistance to short ultraviolet (UV) radiation (2654 A) and its recovery from the injury following illumination with visible light (4350 A, blue) was studied.

2. The resistance of a didinium to UV is considerably increased by feeding it a paramecium 15 to 60 minutes before exposure to UV. If fed just before exposure to UV, the resistance is less than that of an unfed control.

3. Photoreversal is only slightly greater in didinia fed after irradiation with UV but before exposure to visible light as compared to those fed after exposure to visible light.

4. Irradiated paramecia are eaten by didinia, provided they have not started to cytolyze. Didinia fed on irradiated paramecia divide at about the same rate as controls or slightly faster.

5. The available stock of Didinium declines in vigor with lapse of time after excystment, as measured by the time required for division. The sensitivity of Didinium to UV did not change essentially during the 5 month period over which tests were made.

6. The theoretical implications of the results are considered.
TRANSMISSION IN FRACTIONATED MONOSYNAPTIC SPINAL REFLEX SYSTEMS
Authors: Lloyd David P. C. , Hunt Carlton C. , McIntyre A. K.
Published: May 2004

A study has been made of conditions that support monosynaptic reflex transmission from afferent fibers of one part of a synergic muscle mass to motoneurons of another part. Heteronymous response so called can be brought on by prior tetanization of the afferent pathway and by asphyxiation to a critical stage. The response is facilitated by cooling and may appear in the cold preparation without need for prior tetanization.

By appropriate asymmetrical subdivision of a monosynaptic reflex system an afferent inflow can be obtained that is sufficiently powerful to secure heteronymous transmission without the need for prior tetanization or cooling. Each junction between a monosynaptic afferent fiber and a motoneuron possesses some degree of potentiality for transmitting. Transmitter potentiality of an afferent fiber at its several junctions with motoneurons varies widely. Reasons are advanced for supposing the variation to be graded rather than stepwise, and quantitative rather than qualitative.
THE TRANSPORT OF SODIUM INTO HUMAN ERYTHROCYTES IN VIVO
Authors: Gold G. Lennard , Solomon A. K.
Published: May 2004

The relative Na24 specific activity of red cells and plasma was measured at periods up to 30 hours following a single intravenous injection of Na24 in normal healthy young adults. The average specific activity of the red cells relative to that of the plasma at 24 hours and beyond was found to average 0.83 ± 0.05 in a series of five normal individuals, significantly different from 1.0. This indicates that all the intracellular Na is not exchangeable in 24 hours, and confirms earlier in vitro results. The red cell Na concentration in man was shown to be 12.1 ± 1.1 m.eq. Na/liter red cell, as measured in a series of nineteen normal healthy young adults. A theoretical analysis of the data on exchangeable cell Na suggests that the red cell Na (5.3 m.eq. Na/liter blood) is divided into a fast compartment comprising 4.25 m.eq. Na/liter blood, and a slow compartment comprising 1.07 m.eq. Na/liter blood. If these compartments are arranged in parallel, the flux between plasma and fast compartment is 1.32 m.eq. Na/liter blood hour, and that between plasma and slow compartment is 0.016 m.eq. Na/liter blood hour. Results of experiments on two patients with congenital hemolytic jaundice suggest that the fraction of slowly exchanging Na may increase with the age of the red cell.
HISTONES WITH HIGH LYSINE CONTENT
Authors: Daly M. M. , Mirsky A. E.
Published: May 2004

1. The preparation and properties of lysine-rich histones, which differ in a number of respects from the classical arginine-rich histones, have been described.

2. Lysine-rich histones, like those previously known, are located in cell nuclei.

3. Lysine-rich histones dissociate more readily from combination with nucleic acid than do other histones.
INACTIVATION OF BACTERIOPHAGES BY DECAY OF INCORPORATED RADIOACTIVE PHOSPHORUS
Authors: Stent Gunther S. , Fuerst Clarence R.
Published: May 2004

The inactivation of the phages T1, T2, T3, T5, T7, and λ by decay of incorporated P32 has been studied. It was found that these phages fall into two classes of sensitivity to P32 decay: at the same specific activity of P32 in their deoxyribonucleic acid (DNA), T2 and T5 are inactivated three times as rapidly as T1, T3, T7, and λ. Since the strains of the first class were found to contain about three times as much total phosphorus per phage particle as those of the second) it appears that the fraction of all P32 disintegrations which are lethal is very nearly the same in all the strains. This fraction α depends on the temperature at which decay is allowed to proceed, being 0.05 at –196°C., 0.1 at +4°C., and 0.3 at 65°C.

Decay of P32 taking place only after the penetration of the DNA of a radioactive phage particle into the interior of the bacterial cell can still prevent the reproduction of the parental phage, albeit inactivation now proceeds at a slightly reduced rate. T2 phages inactivated by decay of P32 can be cross-reactivated; i.e., donate some of their genetic characters to the progeny of a mixed infection with a non-radioactive phage. They do not, however, exhibit any multiplicity reactivation or photoreactivation.

The fact that at low temperatures less than one-tenth of the P32 disintegrations are lethal to the phage particle and the dependence of the fraction of lethal disintegrations on temperature can be accounted for by the double stranded structure of the DNA macromolecule.
THE INACTIVATION OF DILUTE SOLUTIONS OF CRYSTALLINE TRYPSIN BY X-RADIATION
Authors: McDonald Margaret R.
Published: May 2004

The proteolytic activity of dilute solutions of clystalline trypsin is destroyed by x-rays, the amount of inactivation being an exponential function of the radiation dose. The reaction yield increases steadily with increasing concentration of trypsin, varying, as the concentration of enzyme is increased from 1 to 300 µM, from 0.068 to 0.958 micromole of trypsin per liter inactivated per 1000 r with 0.005 N hydrochloric acid as the solvent, from 0.273 to 0.866 with 0.005 N sulfuric acid as the solvent, and from 0.343 to 0.844 with 0.005 N nitric acid as the solvent. When the reaction yields are plotted as a function of the initial concentration of trypsin, they fall on a curve given by the expression Y α XK, in which Y is the reaction yield, X is the concentration of trypsin, and K is a constant equal to 0.46, 0.20, and 0.16, respectively, with 0.005 N hydrochloric, sulfuric, and nitric acids as solvents. The differences between the reaction yields found with chloride and sulfate ions in I to 10 µM trypsin solutions are significant only in the pH range from 2 to 4.

The amount of inactivation obtained with a given dose of x-rays depends on the pH of the solution being irradiated and the nature of the solvent. The reaction yield-pH curve is a symmetrical one, with minimum yields at about pH 7. Buffers such as acetate, citrate, borate and barbiturate, and other organic molecules such as ethanol and glucose, in concentrations as low as 20 µM, inhibit the inactivation of trypsin by x-radiation. Sigmoid inactivation-dose curves instead of exponential ones are obtained in the presence of ethanol.

The reaction yields for the inactivation of trypsin solutions by x-rays are approximately 1.5 times greater when the irradiation is done at 26°C. than when it is done at 5°C., when 0.005 N hydrochloric acid is the solvent. The dependence on temperature is less when 0.005 N sulfuric acid is used, and is negligible with 0.005 N nitric acid.

The difficulties involved in interpreting radiation effects in aqueous systems, and in comparing the results obtained under different experimental conditions, are discussed.
A QUANTITATIVE ELECTROCHEMICAL THEORY OF THE ELECTROLYTE PERMEABILITY OF MOSAIC MEMBRANES COMPOSED OF SELECTIVELY ANION-PERMEABLE AND SELECTIVELY CATION-PERMEABLE PARTS, AND ITS EXPERIMENTAL VERIFICATION
Authors: Neihof Rex , Sollner Karl
Published: May 2004

The theory of the electrolyte permeability of mosaic membranes composed of ideally anion-selective and ideally cation-selective parts in juxtaposition is tested in a model which consists of an all-electrolytic cyclic arrangement of four component parts: dilute solution/anion-selective membrane/concentrated solution/cation-selective membrane/dilute solution. In this system cations move from the concentrated to the dilute solution across the cation-selective membrane and an equivalent number of anions move through the anion-selective membrane. This movement of ions corresponds to a flow of current in the system. According to the theory, the number of equivalents of electrolyte which penetrate in any given time across the membranes must be identical with the number of faradays of electricity which flow during the same period. The system is essentially a combination of two menbrane-concentration cells arranged in series in a short-circuited state without the presence of electrodes.

Experimentally the magnitude of the current was determined by measuring with probe electrodes the potential across an element of the circuit whose resistance was known and constant. The number of faradays of electricity (determined from time-current data) flowing in the system during a measured time was compared with the analytically determined number of equivalents of electrolyte which moved across the membranes during the same period. In a variety of experimental systems the two values show a 1:1 ratio with a mean deviation of ± 1.8 per cent.
PROPERTIES OF DORSAL ROOT UNMEDULLATED FIBERS ON THE TWO SIDES OF THE GANGLION
Authors: Gasser Herbert S.
Published: May 2004

As an aid in the interpretation of the physiological properties of unmedullated nerve fibers, particularly those having their cells of origin in the dorsal root ganglia, more precise information about their morphology has been acquired through employment of the electron microscope.

The appearance of the fibers in the skin nerves is described, with special reference to the structure of their sheaths; and a notation is made about the bearing of the axon-sheath relationship on the biophysical mechanism of conduction (p. 714).

There is no basic difference between the sheath systems of the d.r.C and the s.C fibers.

Attention is called to a point of similarity between the sheaths of unmyelinated and myelinated axons (p. 715).

An assessment was made of the likelihood of interaction between the fibers. In action potentials showing temporal dispersion at several distances, the elevations appeared in their calculated positions. A model of a group of Schwann sheaths was constructed from successive electron microscope sections, showing that the lengths of the sheath branches are short in comparison with the wave lengths of the action potentials. Supported by these and other considerations, the argument is strongly in favor of the conclusion that among d.r.C fibers, as in other fibers, there is no cross-excitation between the axons.

A new analysis of the size distribution of the fibers in a sural nerve was made from electron microscope pictures; and from the measurements the action potential was constructed. The result confirmed the view, previously expressed, that the velocities of conduction in the fibers can be precisely accounted for by multiplying the diameters by a constant.

In the dorsal roots, the striking change that takes place in the appearance of the fibers and their disposition in the Schwann sheaths can be seen in Fig. 11. The axons partake of the special properties of the peripheral branches, which necessitated the creation of the subdivision of d.r.C fibers. But, their diameters are much smaller. At a set of reduced conduction velocities the configuration of the compound action potential in the nerves is repeated in the roots, with the root velocities still conforming to the size-velocity rule derived from nerve axons.
EFFECT OF BLOOD THROMBOKINASE, AS INFLUENCED BY SOY BEAN TRYPSIN INHIBITOR; ULTRACENTRIFUGATION, AND ACCESSORY FACTORS
Authors: Milstone J. H.
Published: May 2004

1. Crystallized soy bean trypsin inhibitor, at a concentration of 100 µg./ml., suppressed the production of thrombin from a mixture of prothrombin and blood thrombokinase. The experiment was performed in the presence of 0.011 M oxalate, in order to minimize the possibility of participation by accessory factors which require ionic calcium. The results are in accord with the view that thrombokinase is a trypsin-like enzyme.

2. When a solution of blood thrombokinase was centrifuged at 85,000 g for 120 minutes, almost all the activity remained in the supernate. This supernate activated the supernate from a prothrombin solution which had been similarly centrifuged. The activation of prothrombin by thrombokinase can proceed in the absence of material completely sedimentable in 120 minutes at 85,000 g.

3. An "accelerator" reagent was prepared by treating bovine serum with barium carbonate, and then passing the serum through a column of diatomaceous earth. This "accelerator" was used together with prothrombin, blood thrombokinase, Howell's cephalin, and calcium chloride to compose a five-reagent thrombin-producing system. In this system, no thrombin was produced without thrombokinase. On the other hand, thrombin was produced from prothrombin and thrombokinase, even when all the other reagents were omitted. When calcium was omitted, thrombokinase was able to function; but cephalin and the "accelerator" reagent were ineffective.

4. Quantitative tests indicated that the "accelerator" reagent exerted an effect distinct from those of thrombokinase and cephalin. However, it is not certain whether the "accelerator" reagent functioned as an accessory factor, as a potential source of more thrombokinase, or both. In the experiments reported, thrombokinase was primary to, or necessary for, the effect of "accelerator."

5. The effectiveness of thrombokinase was multiplied a hundred times or more, when complemented by calcium, cephalin, and "accelerator" reagent. Ionic calcium was a necessary component of this complementing system. This may help to explain why removal of calcium ions keeps blood fluid, even though thrombokinase, by itself, is little influenced either by calcium ions or by oxalate.
MONOSYNAPTIC REFLEX RESPONSES OF INDIVIDUAL MOTONEURONS
Authors: Lloyd David P. C. , McIntyre A. K.
Published: May 2004

Individual motoneuron responses to a variety of afferent inputs have been examined. At a given input some motoneurons respond to every trial, some to no trial, and some respond to a certain percentage of trials that is characteristic for the motoneuron at that input. The performance of a motoneuron is expressed by means of a firing index that relates the number of responses to the number of trials.

In a representative assemblage of individual motoneurons some 20 to 30 per cent display intermediate firing indices. This number, comprising an "intermediate zone" remains fairly constant at different levels of input although the individuals within it may be entirely different at two different levels of input.

Frequency distribution of individuals with respect to firing indices is U-shaped.

Intermediacy of firing indices depends upon temporal fluctuation of excitability which, in the first approximation, is normal.

The individual motoneurons are approximately equally frequently distributed with respect to transmitter potentiality of their monosynaptic reflex afferent connections.

The distribution of motoneurons with respect to transmitter potentiality of their monosynaptic reflex connections is considered representative of a natural pool in that the sum of their individual post-tetanic response behaviors accurately reproduces the course of post-tetanic potentiation in a natural pool.
SILICON METABOLISM IN DIATOMS
Authors: Lewin Joyce C.
Published: May 2004

1. Evidence is presented that silicon uptake in the diatom Navicula pelliculosa is linked with aerobic respiration.

2. Cyanide, fluoride, iodoacetate, arsenite, azide, and fluoroacetate, at concentrations inhibitory to respiration, were also inhibitory to silicon uptake.

3. 2,4-Dinitrophenol (1 to 2 x 10–5 M) stimulated respiration by 100 per cent, but almost completely inhibited silicon uptake.

4. The respiratory quotient of non-Si-deficient cells decreased from 0.93 to 0.75 after 4 days of starvation in darkness. Glucose (1 per cent) raised the respiratory quotient of such starved cells to 1.05.

5. Silicate (20 mg. Si/liter) stimulated respiration of unstarved Si-deficient cells by about 40 per cent. The effect of silicate on the respiration of Si-deficient cells which had been starved in darkness for 4 days was less marked.

6. The respiratory quotient of Si-deficient cells decreased from 0.8–0.9 to 0.3 after 4 days of starvation in darkness. The addition of silicate to starved cells raised the quotient to 0.5. This represented a 25 per cent stimulation of oxygen uptake concomitant with a 90 per cent stimulation of carbon dioxide evolution.

7. Glucose (1 per cent) caused an increase of respiratory quotient in starved cells from 0.3 to 0.7–0.8. The addition of silicate had no effect on the R.Q. during the oxidation of exogenous glucose.

8. Substrates (glucose, fructose, galactose, lactate, succinate, citrate, glycerol), which caused a stimulation of respiration in starved cells, also stimulated silicon uptake by those cells. However, the stimulation of silicon uptake (50 to 100 per cent) was not proportional to the respiratory stimulation by these substrates (30 to 300 per cent).
THE VARIATION IN THE CORPUSCULAR HEMOGLOBIN CONCENTRATION IN THE HUMAN RED CELL, AS MEASURED BY DENSITOMETRY
Authors: Ponder Eric , Barreto Delia
Published: May 2004

This paper deals with measurement of the hemoglobin concentration in individual human red cells, the concentration being measured as a function of the optical density, at 5461 A, of the central part of the cell in its spherical form. A number of technical difficulties, principally concerned with the effects of focus, have been met with, and these are described in detail. The results show that the coefficient of variation of the hemoglobin concentration is relatively small (about 5.5 per cent) in the case of fresh human red cells in ACD solution, that the coefficient of variation is almost doubled when the red cells have been stored for 6 weeks at 4°C. or when heparin is used as an anticoagulant instead of ACD solution, but that the average hemoglobin concentration is substantially the same in all three cases. The increase in the coefficient of variation found when the red cells have been stored or when heparin is used is probably due to volume changes, some cells shrinking while others swell.
MICROANATOMY OF THE ABDOMINAL STRETCH RECEPTORS OF THE CRAYFISH (ASTACUS FLUVIATILIS L.)
Authors: Florey Elisabeth , Florey Ernst
Published: May 2004

Microanatomical studies on the abdominal stretch receptor organs of the crayfish Astacus fluviatilis L. have been carried out in order to establish a basis for the physiological work that has been, and is being carried out on stretch receptors of various species of crayfish.

Important differences have been found between these organs and those previously described by Alexandrowicz for the lobsters Homarus vulgaris and Palinurus vulgaris.

With the aid of silver-impregnated preparations the relationship of sensory endings and muscle fibers has been shown as well as the pattern of the efferent innervation. The physiological significance of the histological findings has been discussed.
THE PARALLELISM BETWEEN THE ACTION POTENTIAL, ACTION CURRENT, AND MEMBRANE RESISTANCE AT A NODE OF RANVIER
Authors: Tasaki I. , Freygang W. H.
Published: May 2004

1. Simultaneous measurements of action potential and resistance and of action current and impedance change have been made at a single node of Ranvier.

2. There is a parallelism between action potential, action current, and resistance change measured at a node of Ranvier.

3. Some implications of these results have been discussed in relation to the corresponding data obtained from the squid giant axon.
KINETICS OF ION MOVEMENT IN THE SQUID GIANT AXON
Authors: Shanes Abraham M. , Berman Morris D.
Published: May 2004

The loss of Na22, K42, and Cl36 from single giant axons of the squid, Loligo pealii, following exposure to an artificial sea water containing these radioisotopes, occurs in two stages, an initial rapid one followed by an exponential decline. The time constants of the latter stage for the 3 ion species are, respectively, 290, 200, and 175 minutes. The outflux of sodium is depressed while that of potassium is accelerated in the absence of oxygen; the emergence of potassium is slowed by cocaine, while that of sodium is unaffected. One cm. ends of the axons take up about twice as much radiosodium as the central segment; this difference in activity is largely preserved during exposure to inactive solution. Such marked differences are not observed with radiopotassium. From the experimental data estimates are given of the influxes and outfluxes of the individual ions. The kinetics of outflux suggests a cortical layer of measureable thickness which contains the ions in different proportions from those in the medium and which governs the rate of emergence of these ions from the axon as though it contained very few but large (relative to ion dimensions) pores.
THE BIREFRINGENCE OF THE HUMAN RED CELL GHOSTS
Authors: Ponder Eric , Barreto Delia
Published: May 2004

The type of birefringence described by Mitchison, which extends some 0.5 µ in from the surface of the human red cell ghost in glycerol and which shows a maximum retardation of about 7 A, is only found in ghosts which are sufficiently well hemoglobinised to be seen with the ordinary microscope. Ghosts from which all hemoglobin has been lost are not visible with the ordinary microscope and are not birefringent, although they are clearly visible with phase contrast. About 90 per cent of the ghosts in glycerol preparations are of the latter type, the exact percentage being a function of time. Mitchison's measurements of birefringence, although reproducible, accordingly apply only to ghosts in which some hemoglobin still remains complexed with the lipoprotein layers of the red cell ultrastructure, and do not enable one to draw conclusions as to the thickness and orientation of the lipoprotein surface layers.
INITIATION AND ABOLITION OF THE ACTION POTENTIAL OF A SINGLE NODE OF RANVIER
Authors: Tasaki I.
Published: May 2004

1. Using single node preparations of the bull frog or the toad, observations were made on the variation of the voltage across the nodal membrane under various experimental conditions.

2. The time constant of the variation in the membrane voltage caused by a long subthreshold rectangular pulse was of the order of 0.1 msec.

3. The action potential was initiated when the potential inside the node was raised stimulating pulses above a threshold level of approximately 15 mv. for a node in normal Ringer; it was greater in a relatively refractory node and in a partially narcotized node.

4. The variation of the membrane voltage caused by long stimulating pulses of subrheobasic strengths was in general proportional to the strength of the applied pulse. A non-linear behavior of the membrane voltage was observed with barely subthreshold stimulating pulses.

5. The early portion of the action potential of a node was not modified by a direct current which was strong enough to produce measurable potential changes (IR drops) across the resting membrane.

6. A strong pulse of inward current applied to the node during activity abolished the portion of the action potential following the pulse in all-or-none manner.

7. There was no refractory period after a response abolished in its early phase. Following a response abolished later, the recovery in the spike height started from the level of the action potential at the time of abolition.

8. Initiation and abolition of action potentials at a single node are interpreted as "transitions" between the two "equilibrium potential levels" at the node.
THE NATURE OF THE LAMPREY VISUAL PIGMENT
Authors: Crescitelli Frederick
Published: May 2004

From the retina of the land-locked population of the sea lamprey, Petromyzon marinus, a photolabile pigment was extracted which was identified spectrophotometrically as a member of the rhodopsin group of pigments. Using the absorption spectrum of a relatively pure solution and analysis by means of difference spectra, the peak of this pigment was placed at about 497 mµ. The method of selective bleaching by light of different wave lengths revealed no significant amounts of any other pigment in the extracts. A similar pigment was also detected in retinal extracts of the Pacific Coast lamprey, Entospenus tridentatus.

These results are significant for two reasons: (a) the lamprey is shown to be an example of an animal which spawns in fresh water but which is characterized by the presence of rhodopsin, rather than porphyropsin, in the retina; (b) the primitive phylogenetic position of the lamprey suggests that rhodopsin was the visual pigment of the original vertebrates.
WATER FLOW THROUGH FROG GASTRIC MUCOSA
Authors: Durbin Richard P. , Frank Heddy , Solomon A. K.
Published: May 2004

The transport of water through biological membranes can be attributed to several causes. Gradients of chemical activity caused by the application of hydrostatic pressure or differences in solute concentration across the membrane may produce a net water flow, called passive transport (1). In the absence of such gradients a net flow may also occur which is defined as active transport, and is presumed to arise from metabolic processes occurring in the membrane. Pappenhehner, Renkin, and Borrero (2) and Koefoed-Johnsen and Ussing (3) have independently shown that passive flows can be interpreted to give a model of the membrane in terms of pore structure.

In the present study two types of experiments have been performed on passive water transport across the isolated gastric mucosa of the frog. First, the unidirectional diffusion flow of water in either direction has been measured using tritiated water as a tracer. Second, an osmotic gradient has been applied across the membrane and a passive net flow has been measured. At the same time an active net flow in the same direction as HC1 secretion has also been observed.

In addition to the water transport studies, separate measurements have been made of the restriction offered by the membrane to diffusion of various sized molecules. The combined results of these experiments are interpreted in terms of a polydisperse population of pores in the membrane.
PROTEIN SYNTHESIS IN THE PERFUSED RAT LIVER
Authors: Jensen David , Tarver Harold
Published: May 2004

1. When the rat livers are perfused under the conditions of these experiments with rat blood diluted with saline, the livers remain capable of removing colloidal chromic phosphate normally for 4 hours or more; that is, the reticuloendothelial system continues to function normally.

2. Good rates of bile flow continue, generally for 4 hours.

3. The livers incorporate radioactivity from the amino acids methionine, lysine, and histidine at rapid rates for 1 or 2 hours. Thereafter the rates fall.

4. The specific activity of the free lysine and histidine in the perfusate falls rapidly during the experiments (to 25 or 35 per cent of its original value at 10 minutes).

5. The fall in rate of incorporation of radioactivity is attributable to the fall in amino acid specific activity.

6. Addition of a complete amino acid mixture to the perfusate does not appear to have any stimulatory effect on incorporation of radioactivity from labelled amino acids.

7. With lysine, on the assumption that incorporation is due to new protein formation, there is a rate of synthesis equivalent to 230 mg. of plasma protein per 100 gm. of rat per day. This result is in agreement with turnover data obtained from rats in vivo.

8. The results emphasize once again the importance of precursor specific activity in the interpretation of metabolic experiments with labelled amino acids.