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1. Es ist gelungen, Mausecarcinome durch Allgemeinbehandlung der Tiere in einer Sauerstoffatmosphare unter erhohtem Druck zur Heilung zu bringen. 2. Diese Heilung ist unter den gewahlten experimentellen Bedingungen allein mit Sauerstoff moglich. 3. Das Resultat kann durch Kombination der Sauerstoffuberdruckbehandlung mit intravenoser Injektion von Kupfer- und Selenpraparaten verbessert werden. 4. Der Erfolg der medikamentosen Behandlung unter den gewahlten Bedingungen ist gebunden an die Kombination mit Sauerstoffuberdruckbehandlung. 5. Der Heilerfolg ist bisher durch ganz bestimmte Bedingungen begrenzt. Ob diese Grenzen uberwunden werden konnen und damit eine Therapie bosartiger Geschwulste uberhaupt erreicht werden kann, mus vorlaufig als durchaus zweifelhaft angesehen werden.

Die ubliche Messung des Wachstums von Gewebekulturen durch Bestimmung derFlache auf planimetrischem Wege entspricht nicht der Gewichtszunahme, stellt also keine brauchbare Methode zur Feststellung der tatsachlichen Massenzunahme von Gewebekulturen wahrend einer bestimmten Versuchsperiode dar.

Micrococcus radiodurans , a red-pigmented bacterium, is very resistant both to ionizing and to ultra-violet radiations. The dose-response curves in both cases are sigmoidal with high extra-polation numbers. Two non-pigmented mutants of M . radiodurans have been isolated. One of these shows the same type of survival curve as the wild type while the other has an exponential survival curve. Energy transfer reactions including the possible role of pigment have been excluded as a mechanism of resistance. Similarly, resistance is not due to unusual amounts or unique properties of the bacterial DNA . Survivors of both sensitive and resistant bacteria show a lag period following irradiation. In the case of sensitive bacteria no change occurs in the radiosensitivity of the cells during this period. On the other hand, M . radiodurans recovers during the lag period, at the end of which it has become as resistant as the unirradiated cells. All available evidence for the loss of viability in bacteria points to DNA as the target. Recovery of M . radiodurans from radiation damage, therefore, is concluded to be due to repair of damaged DNA by an active cellular, probably enzymic process which occurs during the lag period. The large shoulder of the survival curve and the high extrapolation number are a reflexion of the efficiency of the repair system. The significance of the sigmoidal and exponential survival curves of resistant bacteria is discussed and a theory put forward which postulates two types of damage to the genetic structures, each having a specific repair system. Some experimental evidence in support of this theory is produced.

Most of the work on the effect of fertilization on the metabolism of seaurchin eggs has been concerned with the average rate of O 2 consumption before and after activation. Although observations of this type are of interest, the changes which take place during the actual fertilization of the eggs are more indicative of the mechanisms responsible for the initiation of development. Technical difficulties have impeded experiments of this latter type. Early workers (Warburg 1915) found it necessary to fertilize the eggs before the beginning of the experiment, or, after measuring the O 2 consumption of unfertilized eggs, to open the manometer vessels to effect insemination. The former method precludes any measurements during the fertilization reaction, and the latter involves a period of manipulation and consequent re-equilibration which exceeds the duration of the fertilization reaction. When, therefore, it is stated that the O 2 consumption rate increases upon fertilization or parthenogenetic activation by some 200-400%, what is usually implied is that the O 2 consumption rate measured over a considerable period of time after insemination is some 200-400% more than the rate for a similar period of time before insemination. Shearer (1922) was the first to realize the importance of measurements immediately after insemination; 1 min. After insemination he observed an increase in O 2 consumption which was not maintained at the original high level. We have been unable to confirm Shearer’s results when using a similar method (see fig. 2). In recent years further attempts have been made (e. g. Runnström 1933 b ; Brook, Druckrey and Herken 1938) to make measurements immediately after fertilization by having the sperm inside the manometer vessel before fertilization but separate from the eggs; at a given moment sperm and eggs are mixed; but in these condition, the shortest time interval measured after insemination was 10 min. (Runnström), by which time the initial phase of the fertilization reaction is over.

DURING radiobiological work on bacteria it was found by one of us (H. L.) that the effect of ionizing radiation (X-rays) is greatly potentiated if the bacteria are irradiated in a medium in which water is replaced by heavy water1. Thus, for example, with Escherichia coli B and Pseudomonas 6009 the dose-reduction factor was approximately 2, that is, the X-ray dose required to produce a given reduction in the number of colony-forming bacteria on irradiation in deuterium oxide was one half that in water. This effect, however, occurred only if the bacteria were irradiated in presence of oxygen, but not, or only insignificantly, after irradiation under anaerobic conditions.

Similarity of Repair of Ionizing and Ultra-Violet Radiation Damage in Micrococcus radiodurans

The ophthalmic examination of patients with hypertrophic cardiomyopathy treated with high doses of verapamil over a considerable period of time showed no evidence of a side effect of the drug, thus proving its ocular safety. This could be verified by densitometric image analysis of Scheimpflug photographs of the eyes. The data were used for statistical tests on lens transparency. Changes in lens transparency, i.e. a probable drug-induced cataract were found in none of the patients.

Development of experimental cataract can be objectively monitored in rats by application of Scheimpflug photography with the SL 45 Topcon camera and subsequent densitometric image analysis. The method has been used to study naphthalene cataract in Brown-Norway rats (BN-CPB), as well as diabetic cataract induced by streptozotocin injection in Sprague-Dawley rats. The values obtained by linear microdensitometric image analysis allowed precise characterization of the opacification with respect to size, topography, and time progress so that statistical evaluation of the efficacy of certain drugs in prevention or delay of experimental cataracts was possible.

A double-masked placebo-controlled clinical trial with hard data evaluation by image analysis of Scheimpflug photographs taken at baseline and 6, 12 and 18 months after starting treatment was performed to assess the efficacy of bendazac lysine in four different types of senile cataract. The study had a classical split-plot design. For statistical evaluation, the analysis of variance and covariance for repeated measures were used for three different lens sections: anterior capsule and superficial layer, anterior cortex and nucleus. In the entire group of 53 evaluable patients (without separation into cataract-type subgroups), there was a significantly less increase over time in light scattering (i.e. film blackening) of the anterior cortex and nucleus with bendazac lysine than with placebo. There was also a strong trend in favour of the active drug at the anterior capsular level. Patients with water clefts and spokes showed a significantly less light scattering of the anterior capsule and cortex when treated with bendazac lysine. Those with nuclear changes also showed significantly less light scattering of the anterior cortex and nuclear region with the active drug than with placebo. The number of patients with subcapsular and wedge-shaped (cuneiform) cataracts was too small to be adequately assessed by statistical procedures. Nevertheless, there were indications of a beneficial effect of bendazac lysine on all the lens sections in patients with subcapsular cataracts and on the anterior cortical region in those with wedge-shaped cataracts. In conclusion, this study showed that the increase in light scattering over time, i.e. the progression of cataract, is less in bendazac lysine-treated patients than in those treated with placebo.