Crude enzymes (En(C)) which hydrolyze insoluble glucan produced by Streptococcus mutans FA-1 were extracted from Bacteroides oralis obtained from human dental plaque. Extracellular insoluble glucan of S. mutans (IsG) and the one which was partially modified by Smith degradation (M-IsG) were used as substrates. Commercial dextran (M.W. 2,000,000) was used as control. Composition of the types of glucosidic linkages of the glucans was determined by methylation analysis. The ratio of the α-(1-6) linkage and α-(1-3) linkage was 96.3% and 0.5% for dextran, 29.2% and 55.1% for IsG and 11.9% and 84.9% for M-IsG.
En(C) was extracted by salting out of the culture of B. oralis with 60% saturation of ammonium sulfate. En(C) hydrolyzed IsG, M-IsG and dextran, whereas commercial dextranase (α-1,6 glucanase) hydrolyzed only dextran. IsG was treated with the commercial dextranase until no glucose was detected in the medium, and the remaining material was used for the substrate of enzymes. Release of glucose was detected from the substrate by treatment with En(C), but not with commercial dextranase. These results indicated that En(C) of Bacteroides oralis contained at least two types of glucanase, one being dextranase which hydrolyzes the α-(1-6) linkage and the other the so-called mutanase which hydrolyzes the α-(1-3) linkage.
The effects of acupuncture analgesia were studied using the change in halothane MAC in volunteers. Halothane MAC under electrical acupuncture stimulation was reduced to 86.2 ± 11.1% from the control value. After naloxone administration the level of the MAG was raised to the control level and the increment was 19.l ± 14.8%. Naloxone itself did not change the halothane MAC in the same subjects. These results suggest that the changes in halothane MAC under acupuncture stimulation are caused by the release of an endogenous analgesic substance in the brain.
Nine different decompression tables were evaluated by the method of bubble formation in the agarose gel, the result of which is summarized as follows:
1) The number of bubbles formed in the agarose gel corresponded well with the exposed pressure.
2) The technique of this method was simple and the number of bubbles was accurately counted.
3) This method was considered useful for examining the decompression tables.
4) Using an equation obtained from the experiment with the same agarose gel, the critical number of bubbles at the encl of decompression was found to be 6.6.
5) From this point of view, the R.N.P.L. Table of England and Mano’s Model I Table were considered to be excellent.
6) The first stop at the deeper level during the ascent resulted in a smaller number of bubbles at the end of decompression, indicating the effectiveness of this procedure for the prevention of decompression sickness.
The effects of electroacupuncture (EA) on the rat jaw-opening reflex elicited by tooth pulp stimulation were studied to decide the effective stimulus conditions for electroacupuncture stimulation (EAS). The present study revealed that one of the most important factors for producing a strong EA effect was the stimulus pulse-frequency and that the stimulus pulse-duration was not an essential factor for this effect. In the rat, the following stimulus conditions were very useful for the quantitative study of the EA effect. (1) Stimulation time is 15 min. (2) Stimulus pulse-frequency is 30 to 150 Hz. (3) Stimulus pulse-duration is 0.1 to 5 ms. When the EAS was applied to the Ho-Ku point under these conditions, the degree of the suppression of the jaw-opening reflex was about 50% of the control.