Oscar Raab, working in Herman von Tappeiner's lab, discovered that light affected the toxicity of acridine towards paramecium.
Raab publishes the results of his earlier work, and states that the active radiation was that absorbed by acridine.
O. Gros observes that at a given concentration of fluorescein dyes, the rate of bleaching corresponded to a given concentration. Increase or decrease in concentration above this value is accompanied by a decrease in the rate.
Ledoux-Lebard finds that cytolosis and killing of paramecia treated with eosine and exposed to sunlight occurs faster in shallow dishes than in deep tubes, and concludes that oxygen is a requirement for the reactions, and more oxygen is available in a shallow dish.
A. Jodlbauer conducts studies to determine the effect of x-rays and radium on eosine treated paramecia and enzymes.
H. Tappeiner and A. Jodlbauer show that all substances producing photodynamic phenomena are fluorescent.
W. Straub suggests that oxidization occurs because the photosensitizer combines with molecular oxygen to form a peroxide as a result of the action of light.
W. Straub hypothesizes that photodynamic effects are a result of the direct oxidation of cell components.
E. Hertel finds that the radiation wavelength must be in the absorption spectrum of a dye in order to destroy bacteria.
A. Jodlbauer and H. Tappeiner observe that a lack of oxygen inhibits the destruction of bacteria destroyed by rose bengal, methylene blue, and phenosafranine.
V. Bie finds that molecular oxygen is not required for the destructive effects of ultraviolet radiation to occur.
G. Sacharoff and H. Sachs observe that sodium sulfite prevents photodynamic hemolysis.
A. Jodlbauer and H. Tappeiner conclude that the destruction of enzymes by ultraviolet radiation occurs in the absence of oxygen, but the presence of oxygen is required to produce photodynamic effects on enzymes.
G. Busck (could be Busce) demonstrates that protein constituents of serum might be a contributing factor in the serum protection of red blood cells from photodynamic factors.
K. A. Hasselbalch discovers that a vacuum inhibits hemolysis by light with eosine, methylene blue, and other dyes. This is consistent with his finding that oxygen is required for photodynamic hemolysis.
Friedrich Meyer-Betz injects himself with hematoporphyrin and, following a ten-minute exposure to the sun, develops an inflammation on his face and other exposed skin. Lingering effects included heavy pigmentation and peeling, which lasted for weeks.
P. Metzner finds that oxygen must be present to induce phototropisms, and to kill protozoa, spirilla, and diatoms with photosensitizers.
K. Noack demonstrates that certain plant pigments can be oxidized by light and various photodynamic substances, and that the change in color in the pigments indicates oxidization. He also shows that the addition of manganese salts increases the photodynamic effect of fluorescent dyes, indicating the involvement of a peroxide in the reaction.
G. Viale, over the course of several experiments, finds that several readily oxidizable substances inhibit photodynamic hemolysis, but he obtains some irregular results, especially with serum and casein.
A. Jodlbauer and F. Haffner, after examining studies on a large number of dyes, determine that a correlation exists between the dark reaction and photodynamic action. They conclude that the dyes most active in the dark are also the most photodynamically active.
F. Schanz asserts that photodynamic phenomena occur because of changes in cell constituents as a result of the absorption of electrons emitted by the dye when irradiated.
C. L. A. Schmidt and G. F. Norman observe that hemolysis by eosine and light does not occur in a hydrogen atmosphere. They also find that substances that readily oxidize, e.g., tyrosine and tryptophan, and which react with the Folin Denis reagent also protect red blood cells from hemolysis by eosine and sunlight. They suggest that this might be due to proteins containing tyrosine and tryptophan.
R. W. Wood observes the formation of photocompounds, or colored nonfluorescent substances, upon irradiation of some dyes.
J. H. Clark posits that a shift (from the ultraviolet to the visible region) in the photoelectric threshold of the cell constituents is caused by the sensitizer, and that it corresponds to the dye absorption.
G. Viale's experiments to determine the effect of X-ray and radium on paramecia and enzymes produce negative results.
W. W. Efimoff exposes one sample of eosine treated paramecia to continuous light, and another sample of eosine treated paramecia to intermittent light and darkness. Both samples were killed by exposure to the same amount of energy, proving that the process is not reversible (i.e., no recovery occurs during the darkness).
H. S. Forbes and G. A. Daland find that oxygen is not necessarily involved in the killing of paramecia by ultraviolet radiation.
P. Metzner discovers that the absorption spectrum of certain dyes shifts towards the red when the dye is combined with the cell protoplasm.
W. Hausmann and L. Lšhner discover that some symptoms of photodynamic actions on white mice are inhibited when the surrounding atmospheric pressure is reduced.
T. Awoki observes that a serum injection protects white mice against the fatal effects of sensitization by hematoporphyrin, but inorganic reducing agents offer no protection.
R. Fabre and H. Simonnet find that hematoporphyrin sensitizes red blood cells in visible light.
H. Kammerer and H. Weisbecker agree with Viale that X-rays and radium have no effect on paramecia and enzymes.
H. Gaffron suggests that a sensitizer acts as an oxygen transporter to the acceptor, i.e., the oxidizable substance.
J. Supniewski finds that rabbit intestines are sensitized by hematoporphyrin to only wavelengths it absorbs.
W. Hausmann and C. Sonne state that hematoporphyrin results in sensitization of red blood cells by ultraviolet radiation.
H. C. A. Lassen, working independently, reaches the same results as Hausmann and Sonne (1927).
H. Gaffron demonstrates that peroxides are formed when chlorophyll is irradiated in solution in isoamyl-amine. However, he finds that this is not a peroxide of chlorophyll.
H. Gaffron shows that one molecule of oxygen per quantum of light energy was absorbed when experimenting with an irradiated solution of ethylchlorophylid and ethyl-thiourea in acetone.
W. Hausmann and O. Krumpel suggest that the sensitizing action of porphyrin and trypaflavin occurs in the ultraviolet region, where these substances absorb.
E. N. Rask and W. H. Howell find that some substances containing tyrosine, including euglobulin, pseudoglobulin, egg albumin, and peptone, are not active in inhibiting photodynamic action.
A. Dognon outlines three types of desensitization or inhibition of photodynamic effects: 1) by proteins due to combination with the sensitizer; 2) by reducing substances; and, 3) by the desensitizing action of dyes.
A. Windaus and J. Brinken find that ergosterol exposed to sunlight with eosine and with oxygen present results in the production of a peroxide of ergosterol. A. Windaus and P. Borgeaud find that, in the same setting, but irradiated in a vacuum, erosterin is dehydrogenated.
F. Lippay discovers that sensitized skeletal muscle contracts only by radiations absorbed by the sensitizer.
M. Karschulin proves a general correlation between photodynamic activity and the absorption spectrum.
S. B. Pessoa and J. B. Pereira find that exposure to light from a quartz mercury lamp does not kill paramecia in eosine solution.
J. P. Baumberger, R. T. Bigotti, and K. Bardwell find that coagulation of a mixture of fibrinogen, calcium, and prothrombin is inhibited by methylene blue and light only in the presence of oxygen. In the process, carbon dioxide is given off and oxygen is absorbed.
F. Lippay demonstrates that photodynamic stimulation of striated muscle requires the presence of oxygen. He also observes that horse serum inhibits stimulation of frog's striated muscle by sensitizers and light. He suggests that this is a result of serum hindering the penetration of the sensitizer into the muscle.
Harold Blum finds that exposure to quartz mercury arc irradiation results in less hemolysis of red blood cells in agar plates containing eosine.
Harold Blum finds finds that the hemolytic and fixing actions of irradiated dye are modified by a hydrogen ion concentration in the same way that non-irradiated dye is modified.
Harold Blum demonstrates that hemolysis can occur with a proper concentration of hydrogen peroxide as can the fixation of red blood cells. Both effects are produced by irradiated fluorescine dyes; increase in the dyes increases the effects.
H. F. Blum finds that in cells irradiated simultaneously with the dye, hemolysis occurs more readily than when the dye is irradiated previously.
C. E. Clifton finds that bacteriophage in a vacuum or in nitrogen are not destroyed by light and methylene blue.
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