EFFECTS OF CARBOHYDRATES, PROTEINS, AND BACTERIAL CELLS IN THE HEATING MEDIA ON THE HEAT RESISTANCE OF CLOSTRIDIUM SPOROGENES
It is well known that the heat resistance of bacterial spores is influenced markedly by the nature of the medium in which the spores are heated. This fact is an important problem relating to the practical sterilization in bacteriology and in the food industry. Hence voluminous data on the heat resistance of Clostridium botulinum and Clostridium porogenes in various kinds of foods or food juices have been published (Townsend et al., 1938; Reed et al., 1951; Reynolds et al., 1952). From these data, it can be easily pointed out that the resistance value of a strain in a food is larger than that in phosphate buffer, whereas in another food the resistance value of the same strain is smaller than that in neutral phosphate buffer. Although the pH of the heating media has a marked influence on the thermal death rate of bacteria, it appears that the cause of such a difference in resistance values of a strain cannot be attributed wholly to the variation of pH values of the foods (Sognefest et al., 1948). In fact, there are evidences that some of the ingredients of food might exert a protective effect or a death accelerating effect for the organism during the heating. Weiss (1921) reported that the longer survival time was obtained when the spores of C. botulinum were suspended and heated in the foods with the higher sugar concentration. The similar protective effect of sugars on the bacterial spores has been demonstrated by Anderson et al. (1949) and Sugiyama (1951). Murray and Headlee (1931) found that the presence of peptone in the heating medium had shown sometimes a protective effect for the spores of C. tetani. Recently, Kawai and Tanaka (1952) have shown that several kinds of higher molecular substances, such as gelatin, starch, gum arabic, and alginic acid, have the protective effects for the spores of Bacillus mesentericus and Bacillus brevis. The test organisms used by these workers are relatively less resistant than the most resistant food spoilage bacteria, and the kinds of the substances tested on each strain are rather limited. Thus it seemed important to study the effects of various substances on the most resistant strain. Using the spores of Cameron's putrefactive anaerobe 3679 (Clostridium sporogenes, ATCC 7955), the effects of various carbohydrates, proteins, and bacterial cells were studied. In the previous papers Amaha (1952a,b, 1953) has clearly indicated that the thermal death time of spores of certain strains is influenced markedly by the nature of the recovery media. In general the more favorable was the nature of a medium for the development of heated spores, the longer was the survival time. Hence, it should be considered that the substances added in the basal heating medium have the two stages in their action to the spores; the first, during the heating time, and the second, after the substances were transferred in the subculture medium. In this paper an attempt was made to distinguish the two effects, i.e., the first effect, a true protection, and the second effect, a false protection, of each of substances tested.
In vitro evaluation of cleaning efficacy of detergents recommended for use on dental instruments.
BACKGROUND
The cleaning stage of instrument decontamination processes is a critical control point, and removal of protein deposits is used as a marker of cleaning efficacy. An important factor is the choice of cleaning solution especially in the absence of any defined standards for detergent effectiveness.


METHODS
Following method validation, stainless steel tokens were inoculated with reconstituted citrated blood and added to a 24-multiwell plate and immersed in different cleaning solutions for 5 minutes, agitated at 25 (20°) tilts/min at 22°C and at the manufacturers' recommended temperatures. Desorbed protein was measured using the bicinchoninic acid assay.


RESULTS
From a starting concentration with a median of 3,700 μg of blood protein of all solutions tested, alkaline detergent (Haemo-sol) removed the largest proportion of protein (median, 2,070 μg), and surgical handwash removed the least protein (median, 0 μg). Reverse osmosis water demonstrated useful blood-removing properties with a median of 1,421 μg.


CONCLUSION
The cleaning system we utilized is a simple, inexpensive method to compare the cleaning efficacies of detergents and may be used as a first stage in benchmarking cleaning efficacy of detergents. Not all solutions used in cleaning dental instruments are efficacious at removal of blood.
D'une application pratique des indices bio-météorologiques
Abstract The purpose of the author is to determine statistically in what part of Switzerland maize could be cultivated with certain chance of rentability. The author gives first the method he used for determining the biometeorological index of four species of maize which were selected by the Swiss agronomical research stations. He has considered two possibilities for the growing period: ( a ) raising-ripening (l'approche globale); ( b ) raising-flowering, flowering-ripening (l'approche fractionee). From the biometeorological index, he calculated retrospectively the ripening time of these four species in the years 1901–1965. Assuming a priori that maize should be harvested before October 15th at the latest, he calculated, for a number of meteorological stations, the relative number of years when such conditions were fulfilled. Dividing the country in regions of similar mesoclimates and sorting these stations per region, it is possible to average the maximum altitude where maize can ripen at least 7, 8, 9 and 10 times within 10 years. Finally, taking into account the exposure and ground slope, he draws maps of the theoretically possible extension area, which maps are more reliable and detailed than the ones derived from actual means.