bluuebunny/crossref_metadata_2025_split huggingface dataset:
REVERSIBLE INACTIVATION OF TYPHUS RICKETTSIAE
Authors: Bovarnick Marianna R. , Allen Emma G. 
Published: May 2004

Rickettsiae that have been frozen and thawed in isotonic salt solutions show greatly decreased toxicity for mice, hemolytic activity, respiration, and infectivity for eggs. All these properties can be partially restored by incubation of the rickettsiae in the presence of DPN and coenzyme A for 2 hours at 34°C.
The extent of both inactivation and of subsequent reactivation is markedly affected by the presence of low concentrations of sucrose during the process of freezing and thawing.
It has been shown that DPN is present in rickettsial suspensions and that in preparations that have not been frozen, the DPN sediments with the rickettsiae. After freezing in isotonic salt solution the DPN becomes non-sedimentable.
THE ALTERATION OF INTRACELLULAR ENZYMES
Authors: Kaplan J. Gordin ,   With the Assistance of Woon Ki Paik
Published: May 2004

1. The ability of homologous series of alcohols, ketones, and aldehydes to cause alteration of intracellular catalase increases approximately threefold for each methylene group added, thus following Traube's rule. Equiactive concentrations of alcohols (methanol to octanol) varied over a 4,000-fold range, yet the average corresponding surface tension was 42 ± 2 dynes/cm., that for ketones 43 ± 2, and for aldehydes (above C1) 41 ± 3.
2. Above C8 the altering activity of alcohols ceased to follow Traube's rule, and at C18 was nil. Yet the surface activities of alcohols from nonanol to dodecanol did follow Traube's rule. These two facts show that the interface which is being affected by these agents is not the cell surface, for if it were, altering activity should not fall off between C9 and C12 where surface activity is undiminished; they show also that micelle formation by short range association of hydrocarbon "tails," usually invoked to explain decrease in biological activity of compounds above C8, is not responsible for this effect in these experiments, in which permeability of the cell membrane probably is involved.
3. The most soluble alcohols and aldehydes (alcohols C1 to C8; aldehydes C1, C2), but not ketones, cause, above optimal concentration, an irreversible inhibition of yeast catalase.
4. The critical concentration of altering agent (i.e., that concentration just sufficient to cause doubling of the catalase activity of the yeast suspension) was independent of the concentration of the yeast cells.
5. Viability studies show that the number of yeast cells killed by the altering agents was not related to the degree of activation of the catalase produced. While all the cells were invariably killed by concentrations of altering agent which produced complete activation, all the cells had been killed by concentrations which were insufficient to cause more than 50 per cent maximal activation. Further, the evidence suggested that the catalase may be partially activated by concentrations of altering agent which cause no decrease in viability at all. Hence alteration, unlike death, may not be all-or-none per cell.
6. The fact that the biological criterion being examined was the activation of a water-soluble enzyme rules out the possibility that the reason for the logarithmic increase in altering activity with chain length was increase in concentration of the altering agent in some intracellular fat phase. It is concluded that these surface-active agents cause enzyme alteration by becoming adsorbed at some intracellular interface and thus causing, directly or indirectly, the modification of catalase properties.
7. It is considered that these data support, but do not provide critical proof for, the interfacial hypothesis, which states that catalase is present at the intracellular interface in question, but is desorbed into solution as a consequence of the alteration process.
ROLE OF ELECTROLYTES AND STARVATION IN ALTERING APPARENT RADIOSENSITIVITY OF BAKERS' YEAST
Authors: Bair William J. , Stannard J. N. 
Published: May 2004

1. Respiration and fermentation of yeast receiving 90,000 r of 250 kv. x-rays were studied under a variety of conditions. This dose will nearly completely inhibit growth or colony formation.
2. The apparent effects of irradiation are quite dependent on the K+ and H+ of the suspending medium. At pH 4.5 stimulatory effects were observed in KH2PO2 buffer and inhibition in potassium-free (T-S-T) buffer. At pH 6.5 the situation was reversed and the effects were very small (about 10 per cent). Addition of K+ to irradiated yeast in T-S-T buffer at pH 4.5 can completely reverse the inhibition seen.
3. Starving increases the apparent radiosensitivity of respiration and fermentation, probably by depletion of metabolite and/or electrolyte reserves.
4. Treatment with a cation exchange resin (dowex 50) results in marked inhibition of these processes in irradiated yeast, either fresh or starved. This was most effective if given after irradiation. Almost complete inhibition of anaerobic CO2 production occurs with starvation, irradiation, and dowex treatment combined.
5. The effects of starvation and cation exchange resin treatment can be reversed, though not completely, by adding K+ to the medium.
EFFECT OF STARVING AND DOWEX 50 TREATMENT ON GROWTH OF NORMAL AND X-IRRADIATED YEAST
Authors: Bair William J. , Stannard J. N. 
Published: May 2004

1. Effects of starvation or treatment with a cation exchange resin, dowex 50, parallel in some respects those seen earlier on the respiration and fermentation of bakers' yeast receiving 90,000 r of 250 kv. x-rays. Starvation increased the radiosensitivity of cell division processes whether measured by colony formation or by turbidimetric determination of growth in a liquid medium. The dowex 50 enhanced the radiation effect by the latter measure but appeared to increase colony formation of irradiated yeast.
2. The effects on growth differ from those on respiration and fermentation in that the exchange resin treatment did not inhibit colony formation further, and neither starvation nor resin appreciably altered the growth of non-irradiated yeast.
3. Two effects of radiation are seen in these experiments: (a) a permanent inhibition of growth, and (b) a temporary inhibition of the remaining cells resulting in delay of growth.
4. The irradiated cell is more dependent on certain aspects of its environment in terms of growth responses as well as in terms of metabolism (i.e. respiration and fermentation). Whether or not potassium plays a role in the growth response as it does in the metabolic response cannot be ascertained from the present data.
THE EFFECT OF IODOACETATE AND OTHER INHIBITORS ON PHAGE PRODUCTION AND LYSIS IN THREE PHAGE SYSTEMS
Authors: Baer B. , Shrager S. , Krueger A. P. 
Published: May 2004

The minimal bacteriostatic concentration of iodoacetate, azide, or proflavine was added at intervals during the latent periods of virus in three different bacterium-bacteriophage systems (M. aureus, B. mycoides, E. coli). For each interval at which inhibitor was added, the occurrence of lysis and the final yield of phage were determined. In the B. mycoides and E. coli systems, when added during the first part of the latent period, inhibitor prevented lysis and no phage was released. Introduction of inhibitor during the last part of the latent period resulted in normal lysis and in a linear increase in phage that progressively approached the yield obtained in the absence of inhibitor (the later the introduction, the higher the yield). In the M. aureus system, phage production and lysis in the presence of inhibitor followed the same general pattern, except that release of phage and normal lysis occurred in infected cells to which inhibitor had been added quite early in the latent period.
Our results, when compared with those of Foster (1948) with proflavine and Bozeman et al. (1954) with chloramphenicol, suggest that (1) the final phage yields represent the amount of mature intracellular virus present at the time of addition of inhibitor and (2) the reactions leading to lysis proceed independently of those leading to the formation of mature virus once phage infection has reached a critical point in time.
BINDING OF CALCIUM AND MAGNESIUM BY THE CONTRACTILE ELEMENTS
Authors: Bozler Emil 
Published: May 2004

Using a technique for determining Ca and Mg based on Schwarzenberg's method of titration with ethylenediamine tetraacetic acid (EDTA), it was found that glycerol-extracted muscle fibers contain on the average 0.58 millimole Ca and 0.55 millimole Mg per kg. muscle. The fibers take up additional Ca or Mg from dilute solutions of these metals, but in KCl solutions, the excess is exchanged for K ions.
Inorganic pyrophosphate (PP) removes part of the bound Mg, no Ca; EDTA removes predominantly Ca, but never more than about one-half the total amount. These results are discussed in relation to previous observations on the effects of PP and EDTA on mechanical properties and contractility of extracted muscle fibers.
After the partial loss of bound divalent metals, muscle fibers swell in dilute salt solutions; they also contract slightly and become more translucent.
TRANSMITTER POTENTIALITY OF HOMONYMOUS AND HETERONYMOUS MONOSYNAPTIC REFLEX CONNECTIONS OF INDIVIDUAL MOTONEURONS
Authors: Lloyd David P. C. , McIntyre A. K. 
Published: May 2004

An assemblage of 110 individual tricipital motoneurons has been examined with the aim of determining those factors that predispose certain motoneurons to heteronymous response in post-tetanic potentiation.
Motoneurons that respond most readily to homonymous volleys are not those that respond most readily to post-tetanically potentiated heteronymous volleys. Hence differences in presynaptic organization rather than differences in mean postsynaptic threshold determine differences in readiness for response.
Every motoneuron exhibits a distinct asymmetry in transmitter potentiality of homonymous and heteronymous monosynaptic reflex connections. The range of transmitter potentialities is wide and that of heteronymous connections to some motoneurons is greater than that of homonymous connections to some other motoneurons.
TEMPORAL FLUCTUATION IN EXCITABILITY OF SPINAL MOTONEURONS AND ITS INFLUENCE ON MONOSYNAPTIC REFLEX RESPONSE
Authors: Hunt Carlton C. 
Published: May 2004

Observations on temporal variation in monosynaptic reflex response in the acutely decapitate cat indicate the following:
1. Frequency distribution of response amplitude has a nearly normal form often with some degree of negative skewness. Response variation differs only moderately in form and magnitude from one preparation to another.
2. Temporal variation remains essentially constant at different levels of drive above that level required to complete the zone of variation.
3. The role of response variation in the determination of mean response amplitude is considered.
4. One of the major sources of excitability fluctuation in the "resting" cord is variation in background activity of interneurons.
DECAY OF INCORPORATED RADIOACTIVE PHOSPHORUS DURING REPRODUCTION OF BACTERIOPHAGE T2
Authors: Stent Gunther S. 
Published: May 2004

The multiplication of vegetative T2 bacteriophage in B/r bacteria has been followed by studying the lethal effects of decay of incorporated radiophosphorus P32 at various stages of the eclipse period.
Experiment I. Non-radioactive B/r bacteria were infected with highly radioactive (i.e. P32-unstable) T2 and infection allowed to proceed at 37°C. for various numbers of minutes before freezing the infected cells and storing them in liquid nitrogen. The longer development had been allowed to proceed at 37°C. before freezing, the slower the inactivation of the frozen infective centers by P32 decay. Samples which were frozen after incubation for 9 minutes were completely stable.
Experiment II. Radioactive B/r bacteria in radioactive growth medium were infected with non-radioactive (i.e. stable) T2 and incubated for various lengths of time before being frozen and stored in liquid nitrogen, like those of Experiment I. In this case, the infective centers were stable to P32 decay as long as they were frozen before the end of the eclipse period. The T2 progeny phages issuing from the infected bacteria were P32-unstable.
Experiment III. Radioactive B/r bacteria in radioactive medium were infected with radioactive (i.e. P32-unstable) T2 and otherwise incubated and frozen like those of the first two experiments. In this case, the same progressive stabilization, of the infective centers towards inactivation by P32 decay was observed as that found in Experiment I. The ability to yield infective progeny of infected bacteria incubated for 10 minutes at 37°C. before freezing could no longer be destroyed by P32 decay. The progeny issuing from the infected cells were as unstable as the parental phage.
These results could be explained by one of three general hypotheses. As vegetative phage begins to multiply, it is possible that: (a) there is a high probability that any part of the vegetative phage already duplicated can be saved after its destruction by P32 decay through a process analogous to multiplicity reactivation or, (b) there occurs a change in state of the deoxyribonucleic acid (DNA) preliminary to or in the course of its replication that renders it refractory to destruction by P32 decay, or, finally (c) there occurs a transfer of the genetic factors from the DNA of the infecting phage to another substance not sensitive to destruction by P32 decay.
SYNAPTIC INHIBITION IN AN ISOLATED NERVE CELL
Authors: Kuffler Stephen W. , Eyzaguirre Carlos 
Published: May 2004

Following the preceding studies on the mechanisms of excitation in stretch receptor cells of crayfish, this investigation analyzes inhibitory activity in the synapses formed by two neurons. The cell body of the receptor neuron is located in the periphery and sends dendrites into a fine muscle strand. The dendrites receive innervation through an accessory nerve fiber which has now been established to be inhibitory. There exists a direct peripheral inhibitory control mechanism which can modulate the activity of the stretch receptor. The receptor cell which can be studied in isolation was stimulated by stretch deformation of its dendrites or by antidromic excitation and the effect of inhibitory impulses on its activity was analyzed. Recording was done mainly with intracellular leads inserted into the cell body.
1. Stimulation of the relatively slowly conducting inhibitory nerve fiber either decreases the afferent discharge rate or stops impulses altogether in stretched receptor cells. The inhibitory action is confined to the dendrites and acts on the generator mechanism which is set up by stretch deformation. By restricting depolarization of the dendrites above a certain level, inhibition prevents the generator potential from attaining the "firing level" of the cell.
2. The same inhibitory impulse may set up a postsynaptic polarization or a depolarization, depending on the resting potential level of the cell. The membrane potential at which the inhibitory synaptic potential reverses its polarity, the equilibrium level, may vary in different preparations. The inhibitory potentials increase as the resting potential is displaced in any direction from the inhibitory equilibrium.
3. The inhibitory potentials usually rise to a peak in about 2 msec. and decay in about 30 msec. After repetitive inhibitory stimulation a delayed secondary polarization phase has frequently been seen, prolonging the inhibitory action. Repetitive inhibitory excitation may also be followed by a period of facilitation. Some examples of "direct" excitation by the depolarizing action of inhibitory impulses are described.
4. The interaction between antidromic and inhibitory impulses was studied. The results support previous conclusions (a) that during stretch the dendrites provide a persisting "drive" for the more central portions of the receptor cell, and (b) that antidromic all-or-none impulses do not penetrate into the distal portions of stretch-depolarized dendrites. The "after-potentials" of antidromic impulses are modified by inhibition.
5. Evidence is presented that inhibitory synaptic activity increases the conductance of the dendrites. This effect may occur in the absence of inhibitory potential changes.
THE EFFECTS OF SICKLING ON ION TRANSPORT
Authors: Tosteson D. C. 
Published: May 2004

When the red cells from patients with sickle cell anemia (S-S) were kept in the disk shape by incubation in O2, they maintained cell sodium in the steady state for at least 10 hours. The sodium flux in such cells at 37°C. was 6.0 ± 1.5 m.eq./ (liters RBC) x (hours).
When S-S cells were sickled by incubation in N2, sodium outflux increased two- to threefold, while influx increased four- to fivefold and the cells gained net sodium. A small but undetermined fraction of the sodium in disk and sickle shaped S-S cells exchanges at one or more rates which are substantially slower than those calculated here from the initial rate of transfer of tracer from cells to the medium.
The penetration of tracer Cs into normal and both disk and sickled S-S cells was markedly inhibited by increasing the K concentration in the medium, indicating that Cs and K compete for an entrance pathway in all three cell types. The ratio of the inward rate constant for tracer Cs to that for K42 in normal and disk-shaped S-S cells increased only slightly when the K concentration in the medium was increased, indicating that almost all the Cs entered such cells in competition with K. Sickling accelerated the entrance of tracer cesium into S-S cells. Furthermore, the rate constant ratio increased with increasing external K concentration in sickled cells, suggesting the simultaneous presence of a non-competitive route for cesium influx in this cell type.
The results are interpreted to support the view that sickling (a) accelerates inward transport of K and Cs and outward transport of Na by a non-diffusion, assumed carrier, process and (b) opens pathways for the diffusion of all three ions.
THE INTERACTIONS OF THE NON-SPECIFIC INHIBITOR OF HYALURONIDASE WITH HYALURONIDASE AND PROTEOLYTIC ENZYMES IN VIVO
Authors: Hadidian Z. , Murphy Marguerite M. 
Published: May 2004

1. Following intravenous administration of testes hyaluronidase in rabbits and dogs, there is a decrease in the level of the non-specific inhibitor of hyaluronidase in serum.
2. If a large amount of hyaluronidase is injected, the inhibitor level is reduced to zero and hyaluronidase may be present in serum for some time after the injection. The hyaluronidase activity of such samples of serum increases when the serum is incubated with papain.
3. Hyaluronidase activity is found in the livers of the injected animals in large amounts and this activity is increased considerably when the homogenate of this tissue is incubated with papain.
4. Intravenous administration of several proteases or venom produces a decrease in the serum inhibitor level. Intravenous administration of streptokinase produces such a decrease in rabbits but not in dogs.
5. There is a correlation between the depletion of the inhibitor from the serum and the occurrence of a slow, persistent depression of blood pressure upon administration of proteolytic enzymes.
ANALYSIS OF RESPIRATION DURING GERMINATION AND ENLARGEMENT OF SPORES OF BACILLUS MEGATERIUM AND OF THE FUNGUS MYROTHECIUM VERRUCARIA
Authors: Mandels G. R. , Levinson H. S. , Hyatt M. T. 
Published: May 2004

1. There are certainly two, and probably three, stages in the development of B. megaterium from the spore to inception of cell division. The rapid increase in rate of respiration during the initial 10 minutes on glucose-peptone-yeast extract medium coincides with decrease in optical density and with increase in stainability. From about 10 to 100 minutes, the rate increases linearly, coinciding with swelling of the spores and ending at approximately the time of rupture of the spore case. From about 100 to 180 minutes, there is a second and steeper linear increase in respiration rate coinciding with cell elongation. These physiological and morphological phenomena are discussed as criteria for germination.
2. The rate of respiration of M. verrucaria spores also increases linearly up to about 300 minutes in sucrose-yeast extract medium. No breaks in the curves are observed during formation of the germ tubes.
3. Oxygen uptake follows the parabolic curve
See PDF for Equation
within the limits of experimental error for both types of spores.
4. It is postulated that metabolism during these stages of linear increase may be regulated by processes occurring at cellular or intracellular surfaces or by synthesis of a limiting enzyme at constant rate.
OBSERVATIONS ON AN ATP-SENSITIVE PROTEIN SYSTEM FROM THE PLASMODIA OF A MYXOMYCETE
Authors: Ts'o Paul O. P. , Bonner James , Eggman Luther , Vinograd Jerome 
Published: May 2004

1. Extracts of the plasmodia of the myxomycete, Physarum polycephalum, exhibit reversible decreases in viscosity in response to the addition of ATP under appropriate conditions. The protoplasm material prepared by extraction with KCl solution can apparently exist in either a high or a low viscosity state. As prepared, it is in the low viscosity condition. Rapid and extensive increases in viscosity of the extract are brought about by addition of AMP, inorganic phosphate, or, under certain conditions, of ATP. Only after the high viscosity state has been attained does addition of appropriate quantities of ATP cause a reversible decrease in viscosity.
2. The active principle of crude plasmodial extracts may be concentrated by fractional precipitation with ammonium sulfate and is found in the fraction precipitated between 30 and 40 per cent saturation. This material possesses a higher viscosity than does the original crude extract and is apparently in the high viscosity state since the addition of ATP causes an immediate reversible decrease in viscosity.
3. The ATP-sensitive fraction of myxomycete plasmodia possesses a viscosity which is dependent upon its previous thermal treatment. Extracts incubated at 0° for a period of a few hours increase greatly in viscosity when they are returned to 24.5°. This increased viscosity is structural in nature, is destroyed by mechanical agitation of the solution, and may be reversibly destroyed by addition of ATP.
4. It is suggested that the ATP-responsive protein of myxomycete plasmodia may be related to sol-gel transformations which have been observed in intact plasmodia and may participate in the protoplasmic streaming of the intact organism. This suggestion is based upon the following facts: (a) the protoplasmic streaming of myxomycete plasmodia is increased by microinjection of ATP; (b) the gel portion of the cytoplasm at the site of the microinjection of ATP is extensively converted to the sol state.
The changes in structure of the intact cytoplasm are thus similar in nature to the changes exhibited in response to ATP by the purified ATP-sensitive protein.
5. The ATP-sensitive protein of myxomycete plasmodia appears to undergo reversible aggregation to form a high viscosity state. The function of ATP is to break down the aggregates thus formed. Since a specific ATPase activity is associated with the purified material, added ATP is gradually destroyed and recovery of viscosity attends the spontaneous reconstitution of aggregates.