This article examines the possibility that the components of an informationprocessing system all operate continuously, passing information from one to the next as it becomes available. A model called the cascade model is presented and it is shown to be compatible with the general form of the relation between time and accuracy in speed-accuracy trade-off experiments. In the model , experimentlLlmanipulations may have either or both of two effects on a processing level: They may alter the rate of response or the asymptotic quality pf the output. The effects of such manipulations on the output of a system of proessesare described. The model is then used to reexamine, the subtraction and additive factors methods for analyzing the composition of systems of processes. The examination of the additive factors method yields particularly interesting results. Among them is the finding that factors that affect the rates of two different processes would be expected to have additive effects on reaction times under the cascade model, whereas factors that both affect the rate of the same process would tend to interact, just as in the case in which the manipulations affect the durations of discrete stages. On the other hand, factors that affect asymptotic output tend to interact whether they affect the same or different processes. In light of this observation, the conclusions drawn from several studies about the locus of perceptual and attentional effects on processing are reexamined. Finally, an outline is presented of a new method for analyzing processes in cascade. The method extends the additive factors method to an analysis of the parameters of the function relating response time and accuracy.

On the time relations of mental processes: An examination of systems of processes in cascade.

Alpha-toxin of Staphylococcus aureus.

Reactive oxidant species (superoxide, hydrogen peroxide, hydroxyl radical, hypohalous acid, and nitric oxide) are involved in many of the complex interactions between the invading microorganism and its host. Regardless of the source of these compounds or whether they are produced under normal conditions or those of oxidative stress, these oxidants exhibit a broad range of toxic effects to biomolecules that are essential for cell survival. Production of these oxidants by microorganisms enables them to have a survival advantage in their environment. Host oxidant production, especially by phagocytes, is a counteractive mechanism aimed at microbial killing. However, this mechanism may be contribute to a deleterious consequence of oxidant exposure, i.e., inflammatory tissue injury. Both the host and the microorganism have evolved complex adaptive mechanisms to deflect oxidant-mediated damage, including enzymatic and nonenzymatic oxidant-scavenging systems. This review discusses the formation of reactive oxidant species in vivo and how they mediate many of the processes involved in the complex interplay between microbial invasion and host defense.

https://cmr.asm.org/content/cmr/10/1/1.full.pdf

Role of oxidants in microbial pathophysiology.

Bacillus thuringiensis var israelensis parasporal crystal delta-endotoxin was purified by ultracentrifugation on a discontinuous sucrose gradient. Native delta-endotoxin crystals showed no detectable toxicity in the vitro and in vivo systems that are described. By contrast alkali-solubilized crystal delta-endotoxin caused rapid cytological and cytopathological changes in Aedes albopictus, Choristoneura fumiferana 63 CF1, Spodoptera frugiperda and Trichoplusia ni cell lines as observed by phase-contrast microscopy and vital staining. Mouse fibroblasts, primary pig lymphocytes and three mouse epithelial carcinoma cell types showed a similar response to the alkali-soluble crystal delta-endotoxin. In addition the soluble crystal delta-endotoxin protein caused haemolysis of rat, mouse, sheep, horse and human erythrocytes. Intravenous administration of the alkali-soluble crystal delta-endotoxin to Balb. c mice at a dose rate of 15-30 micrograms of protein per gram body weight resulted in rapid paralysis followed by death within 12h. Subcutaneous inoculation of 15-30 micrograms of protein per gram body weight resulted in death of suckling mice in 2-3 h. The alkali-solubilized crystal delta-endotoxin was not toxic however, when administered per os. A comparison is made with a similar alkali-soluble fraction from the parasporal crystal delta-endotoxin of B. thuringiensis var kurstaki. With the exception of the Lepidopteran cell line, Choristoneura fumiferana 63 CF1, this soluble crystal delta-endotoxin protein showed no in vitro or in vivo toxicity, and no haemolytic activity.

Bacillus thuringiensis var israelensis crystal delta-endotoxin: effects on insect and mammalian cells in vitro and in vivo

Transferrin, biochemistry, physiology and clinical significance

Bernheimer, Alan W. (New York University School of Medicine, New York), and Lois L. Schwartz. Lysosomal disruption by bacterial toxins. J. Bacteriol. 87:1100-1104. 1964.-Seventeen bacterial toxins were examined for capacity (i) to disrupt rabbit leukocyte lysosomes as indicated by decrease in turbidity of lysosomal suspensions, and (ii) to alter rabbit liver lysosomes as measured by release of beta-glucuronidase and acid phosphatase. Staphylococcal alpha-toxin, Clostridium perfringens alpha-toxin, and streptolysins O and S affected lysosomes in both systems. Staphylococcal beta-toxin, leucocidin and enterotoxin, Shiga neurotoxin, Serratia endotoxin, diphtheria toxin, tetanus neurotoxin, C. botulinum type A toxin, and C. perfringens epsilon-toxin were not active in either system. Staphylococcal delta-toxin, C. histolyticum collagenase, crude C. perfringens beta-toxin, and crude anthrax toxin caused lysosomal damage in only one of the test systems. There is a substantial correlation between the hemolytic property of a toxin and its capacity to disrupt lysosomes, lending support to the concept that erythrocytes and lysosomes are bounded by similar membranes.

Lysosomal disruption by bacterial toxins

Effect of staphylococcal and other bacterial toxins on platelets in vitro.

Bernheimer, Alan W. (New York University School of Medicine, New York, N.Y.), and Lois L. Schwartz. Lysis of bacterial protoplasts and spheroplasts by staphylococcal alpha-toxin and streptolysin S. J. Bacteriol. 89:1387-1392. 1965.-Protoplasts of Bacillus megaterium, Sarcina lutea, and Streptococcus pyogenes, and spheroplasts of Escherichia coli were lysed by staphylococcal alpha-toxin, whereas spheroplasts of Vibrio metschnikovii and V. comma were not. In the spectrum of its lytic action, streptolysin S qualitatively resembled staphylococcal alpha-toxin except for failure to lyse S. pyogenes protoplasts. In contrast to the two foregoing agents, streptolysin O did not lyse protoplasts and spheroplasts. The observations are interpreted in relation to similarities and differences in lipid composition of bacterial and mammalian cell membranes.

Lysis of Bacterial Protoplasts and Spheroplasts by Staphylococcal α-Toxin and Streptolysin S

Leucocidal agents of haemolytic streptococci.

SummaryStrains representative of potentially pathogenic and nonpathogenic staphylococci were studied with respect to the extra-cellular proteins that accumulate in cultures. Starch gel electrophoresis of the non-dialyzable substances isolated from culture supernates revealed that 12 to 14 species of proteins are elaborated by potentially pathogenic strains while about half as many were found to be associated with nonpathogenic staphylococci. Additional findings permitted the loci of hemolytic and several enzymatic activities to be mapped and compared with those of protein. Most of the proteins do not appear to be identifiable with previously described products of staphylococcal growth, and therefore, represent new extracellular substances. Several of these occur consistently and perhaps exclusively in association with potentially pathogenic strains.

Schwartz L

Papers

Lysosomal disruption by bacterial toxins

Effect of staphylococcal and other bacterial toxins on platelets in vitro.

Lysis of Bacterial Protoplasts and Spheroplasts by Staphylococcal α-Toxin and Streptolysin S

Leucocidal agents of haemolytic streptococci.

Extracellular Proteins of Staphylococci.