It is commonly known that a certain amount of blood flow is required in the dental pulp to keep the teeth healthy. The amount of the blood flow in the dental pulp is an important factor in the growth of the jaw and teeth. The author studied the changes in the blood flow in dental pulp by applying the dentist's ordinary drugs, alcohol and cigarettes, which often directly touch the dental pulp when it is exposed. The untreated teeth opposite the treated ones were examined for comparison. The follwing results were obtained:
1. Application of disinfectants such as Oxydol, Neocleaner and Rusnon caused a momentary decrease in the blood flow which lasted about twenty to thirty minutes before the flow was restored.
2. Xylocaine, a local anaesthetic, caused a slight increase or a strong momentary decrease in the blood flow. When epinephrine was added to Xylocaine, the effect became apparent, that is, the blood flow clearly decreased.
3. Calvital, a drug made of calcium hydroxide, and a solution of calcium hydroxide, both of which are used as preservatives for teeth, caused a strong momentary or lasting decrease in the blood flow. In cases where the effect lasted, the flow was not restored for more than three hours after the treatment. Two weeks afterwards, however, the blood flow was definitely greater than it had been before the application of these drugs.
4. Acidulated fluoride solution, used for preventing dental caries, definitely decreased the blood flow on the treated side.
5. Liquid detifrice, used as a dental hygienic drug, induced a momentary increase or decrease or no change in the blood flow. The color tester, plaque disclosing solution, had almost no effect on the blood flow.
6. A solution of 20% Etyl alcohol caused a slight a momentary increase or a distinct momentary decrease in the blood flow. Aqueous extract solution of cigarettes brought about a very slight momentary increase or decrease in the blood flow.

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In a previous study, the author confirmed the preservative effect of Calvital through the observation of the blood flow in the dental pulp. In this study, the action of Vitapex (V. drug, hydroxide to which iodoform is added), a root canal filling material which is similar to Calvital, is examined. Dentists usually use V. drug after pulling out the dental pulp in order to plug the cavity. For the purpose of studying the effectiveness of the preservative effect of V. drug, the author measured the blood flow in the dental pulp of the canine teeth of dogs in vivo by the hydrogen gas clearance method after making a small canal reaching the pulp cavity and plugging it with V. drug. The measurement was carried out for thirty weeks at two week intervals.
1. The blood flow is measurable for a long term relative to control, from 14 weeks to 30 weeks or more even in the exposed dental pulp when the pulp has been treated with V. drug. In 10 of 14 cases of untreated canine teeth it was possible to measure the blood flow in dental pulp for from two to four weeks. In three of the remaining four cases the respective periods of measurement were 6 weeks, 22 weeks and 28 weeks. In the final case, the blood flow was measurable for more than 28 weeks.
2. The dental pulp where measurable blood flow is observed owing to the V. drug treatment clearly shows in the field of the microscope the tissues maintaining their functions, that is, the author can clearly distinguish that it is vital pulp. In contrast, the tissue of the dental pulp which has no measurable blood flood does not maintain the form of tissue and it can be definitely determined that the dental pulp is dead.
3. It is important for maintaining the normal function of dental pulp to keep a certain amount of blood flow volume. It is considered that V. drug is effective in maintaining this flow in the vital pulp.
4. It is clearly recognizable that blood flow is histologically maintained in the examined pulp which has blood flow measurable by the hydrogen gas clearancee method. If blood flow in the dental pulp is unmeasurable by this method, the blood vessels in the dental pulp can't be recognized histologically. It is apparent from this agreement that the hydrogen gas clearance method is useful for observing the movement of the local blood flow.

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The effects of a wide variety of ecological factors on the age-specific mortality rates from cerebrovascular, ischemic heart and hypertensive diseases in 46 prefectures in Japan for the years 1970 and 1975 were analyzed by stepwise regression analysis. The following factors were positively related to the mortality rates in the two years: (1) rural residence for cerebrovascular disease in middle-aged and elderly persons and young men, and for ischemic heart disease in middle-aged persons; (2) low income for hypertensive disease in elderly persons and middle-aged women; and (3) urban residence for cerebrovascular disease in middle-aged men. In contrast, the aged population factor was inversely related to the mortality from ischemic heart disease in elderly persons and to that from cerebrovascular disease in middle-aged men. The mortality from ischemic heart disease in women aged 65-and-above significantly increased between 1970 and 1975.

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The thermal diffusion method is based on a linear relationship between thermal conductivity of tissue and the tissue blood flow. Therefore, thermal diffusion is very sensitive to changes in tissue blood flow. However, it has been impossible to assess tissue blood flow quantitatively by this method. For the quantitative dynamic assessment of body surface circulation, a thermal diffusion flow probe incorporating a Peltier stack was used. In order to modify the apparatus using this probe for measuring body surface circulation continuously, fundamental studies about the measurement of human skin blood flow were carried out in the finger using the thermal diffusion method. The results obtained were as follow.
1) The voltage difference of the thermocouples (V) of a probe placed on plates of various materials similar in the thermal conductivity to human skin was measured. A highly positive correlation between the thermal conductivity of the material and the reciprocal number of the voltage difference of the thermocouples (1/V) (r=0.973, p<0.001) could be observed. The use of this probe enabled us to assess the thermal conductivity of materials and tissues quantitatively.
2) V gradually increased in parallel with the finger ischemia induced by inflation of a touniquet, suggesting that V varied with the change of finger blood flow and that its baseline was steady.
3) A highly significant positive correlation was obtained between finger blood flow measured by the inhaled hydrogen clearance method (Hydrogen_i FBF) and 1/V (r=0.949, p<0.001). V with no flow (V₀) and constant Φ was estimated, and a calibrating line based on the following equation was determined.
F=Φ(1/V-1/V₀)
Finger blood flow measured by the thermal diffusion method (Thermal FBF) was obtained. A highly significant positive correlation was obtained between Hydrogen_i FBF and Thermal FBF (r=0.949, p<0.001).
4) A highly significant positive correlation was obtained between finger blood flow measured by an electrochemically generated hydrogen clearance method (Hydrogen_e FBF) and 1/V (r=0.953, p<0.001). Calibration by this method was carried out taking account of the apparent flow by diffusion of hydrogen gas to the surrounding area (Diffusion Flow). A highly significant positive correlation was obtained between Hydrogen_e FBF subtracted Diffusion Flow and Thermal FBF (r=0.953, p<0.001).
5) Thermal FBF calibrated by the electrochemically generated hydrogen clearance method almost agreed with that determined by the inhaled hydrogen clearance method in terms of the absolute value of the finger blood flow.
Using the thermal diffusion method calibrated previously by the hydrogen clearance method in normal human subjects, the absolute value of skin blood flow can be measured continuously and noninvasively in humans. It was concluded that the apparatus for measuring skin blood flow continuously by the thermal diffusion method could be utilized as a monitor of the body surface circulation and was thus useful for diagnosis and research in various medical fields.

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The present study aimed to clarify the mechanism and conditions for carcinogenic N-nitrosopyrrolidine (NPYR) formation in bacon during the cooking process, analyzing the precursors of N-nitrosamines in various materials, including raw pork and spices. Results obtained are summarized as follows:
1. When bacon samples were brought to 100°-200°C within 10 minutes, the amounts of NPYR formed from free proline via pyrrolidine (Pyr) were almost the same levels as those formed via N-nitrosoproline (NPRO). In contrast, when samples were heated at 225°C, the yield of NPYR via Pyr was apparently greater than that formed via NPRO.
2. Concerning the precursors of N-nitrosamines in fresh pork samples, spermine, a polyamine, was found to range from 50-100mg/kg, while levels of other polyamines were less than 1/10 of the spermine level.
3. With regard to the precursors of nitrosamines in spices used for preparing commercial bacon, it was found that only pepper contained such compounds among the various spices so far tested, viz., pyrroperine and Pyr were detected, and both compounds are precursors of NPYR. In addition, piperine and piperidine which form N-nitrosopiperidine after a nitrosation reaction were isolated. The rates of nitrosation of the aforementioned compounds under acidic conditions at 37°C and 100°C were also studied.

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The Blackpool table was used in Hong Kong subway construction work where we did medical consultation on how to prevent decompression sickness. Between 1975 and 1984 there were 260 bends patients out of 28, 554 workers who were exposed to pressures of between 1.2 and 2.8kg/cm², and the incidence of decompression sickness (bends) was 0.91%. This percentage of bends is considered quite acceptable.
The Blackpool table has been recognized as one of the safest decompression schedules experimentally but it became clear that its schedule for the prevention of decompression sickness could be improved upon through observation and evaluation by a bubble counting technique using an agarose gel model.
The Model One table, which was developed by us, was applied to the Blackpool table to decrease the incidence of bends. These two decompression schedules were checked by a bubble counting technique. The special feature of the Model One table is that it utilizes the initial decompression ratio between the bottom pressure and the first stop of decompression; i. e., the slow decompression ratio of 0.1kg/cm²/min, in contrast with the Blackpool table.
The extension of the total decompression time is less in Model One than in the Blackpool schedule, however, the number of bubbles formed in the agarose gel model decreased significantly and the incidence of bends was also decreased by nearly one half.
This demonstrates that the initial decompression ratio is another key for decreasing the incidence of bends.

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Decompression sickness (bends) is generally considered to be due to the effects of bubbles which originate from supersaturated gas dissolved in the blood and other tissues.
The bubbles in the tissues are formed from pre-exisiting gas nuclei. The gas initially diffused into the gas nuclei in the tissue and is then forced out by decompression, depending on the difference between the inside tension of the gas nuclei and the surrounding tension of the tissue.
Mammalian gelatin samples were first used according to this theory by LeMessurier in 1972 as a model in the etiology of bends, and further careful research has been carried out by Beckman, Yount, Mano and their co-workers. Mano et al. have evaluated the relative effectiveness of standard decompression tables in reducing bubble formation using the agarose gel bubble technique under rigorously controlled conditions.
Bubble formation is mainly due to the decompression ratio, accompanied by hyperbaric exposure; however, the variation of exposure temperatures also influences the formed bubbles even though there are no decompression steps.
Therefore, to understand the relation between the temperature and bubble formation, research was undertaken. This bubble work is composed of two groups of experiments. One involved saturation experiments, and the relation between the number of bubbles and different saturation pressures was obtained as a regression line. The temperature was controlled at 20.0±1.0°C.
In the other experiments, the environmental temperature was changed between 5 and 30°C. Agarose gel samples, with 15 cells in a set, were exposed to the same bottom pressure but the environmental temperature was varied in each set of conditions.
The number of bubbles was counted in each sample and the cells were heated to 30°C for 30min and bubble counting was then done. The exposure time at the bottom pressure was 30, 60, or 120min in the non-saturation experiments and 6 hours in the saturation experiments. The phenomena of bubble formation according to the variations of the temperature were investigated in detail, and, eventually, significant regression equations could be obtained with good relations in all defferent conditions of hyperbaric exposure.
This result gives us much information on bubble formation phenomena, which can aid us in carrying out our basic research on decompression sickness, especially as concerns the influence of environmenal temperature, although there are differences between in vitro and in vivo phenomena. Moreover, the standard decompression table by the Ministry of Labour could be evaluated by this bubble counting technique. The safety of the table was questionable, and it was recognized that the table was not necessarily correct. This research will be applied to various fields of diving or compressed air work in the future.

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The adsorption properties of surface-modified activated carbon for the treatment of the effluent from hospitals were investigated.
The relationship between the amounts of phenol and cresol adsorbed and the pore structure of the adsorbent was not significant. However, the difference in the amount adsorbed could be explained from the interaction between the surface charge of the activated carbon and phenolic anions.
The intraparticle diffusivity of phenol and cresol onto surface-modified activated carbon was greater than that onto AC for each adsorption ratio. For NC-AC and PT-AC, our experiments indicate that the large values for the intraparticle diffusivity are due to the interaction between the surface charges of the adsorbent and adsorbate, and the increase in the transitional pore volume, respectively.
It is found that NC-AC is suitable for the treatment of effluent from hospitals.

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In mouse spleen cells, the effects of chloroplatinic acid and zirconium oxychloride on IgM antibody production against sheep red blood cells (SRBC) were studied in vitro. The following conclusion were drawn from this study:
1. Chloroplatinic acid suppressed direct plaque formation against SRBC in mouse spleen cells in vitro.
2. The viability of mouse spleen cells, to which chloroplatinic acid was added was higher than that of control when they were cultuerd in a CO₂ incubator for 4 days.
3. Zirconium oxychloride enhanced direct plaque formation against SRBC in mouse spleen cells in vitro.
4. Direct plaque formation in mouse spleen cells blended with macrophages obtained from mice intraperitoneally injected with zirconium oxychloride for a week showed a larger increase in response than when there was no addition of Zr-sensitized macrophages.
From these results, it is suggested that the suppressed IgM immune response resulting from the addition of chloroplatinic acid may due to activated suppressor T cells, and that the enhanced response brought about by adding zirconium oxychloride may depend upon activated macrophages.

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The present study attempted to determine regression equations which can be used to predict body density from anthropometric indices. Multiple regression and factor analysis were applied to variables including body density and other anthropometric indices such as height, weight, girth and skin-fold thickness (SFT), age, and sports experience. The data used were from 81 female college students. Body density was calculated by body weight and whole body volume, which was measured by an underwater weighing method in swimming pool. The main findings were as follows;
1. The body density of the above mentioned students estimated by this method was 1.0480±0.0126 (mean±S. D.: standard deviation). That of subjects with no sports experience (N=23) was 1.0433±0.0120. This approximately agrees with the figures for a normal group, measured and estimated by other researchers.
2. Variables for the factor analysis were age, sports experience, height, weight, body density, girth of chest, waist, upper arm and thigh, and SFT of triceps, subscapular, lateral abdomen and front of the thigh. Factors used for this analysis were Factor 1, which indicated body weight and girth, Factor 2, in which SFT was measured, Factor 3, indicating trunk SFT, and Factor 4, denoting body height. Body density was included in Factor 2. The eigenvalues of factors one to four were over 1.0, which accounted for 77.7% of the cumulative contribution rate (coefficient of determination).
Meanwhile, another factor analysis was done using variables frequently measured in the field of health care services: age, height, weight, body density, girth of chest, waist and upper arm, and SFT of triceps, subscapular and lateral abdomen. Factors used for this analysis were Factor 1, which indicated body weight and girth, Factor 2, SFT, and Factor 3, body height. Body density was included in Factor 2. The eigenvalues of factors one to three were over 1.0, which accounted for 67.3% of the cumulative contribution rate.
3. The multiple linear regression equation for screening those currently engaged in sports practices is Yc=1.062221-0.001166⋅X₁+0.005512⋅X₂, where X₁: triceps SFT, and X₂: sports experience score; 2=active, 1=active in the past, 0=no sports experience, and R=0.619(p<0.001). For the screening of the obesity of general subjects, another equation is applicable: Yc=0.994044-0.000979⋅X₁-0.000755⋅X₂+0.000693⋅X₃, where X₁: triceps SFT, X₂: weight, and X₃: height, and R=0.590(p<0.001). The results of these multiple linear regression equations showed no significant difference compared with thosee previously reported. Body density estimates using these variables and equations are simpler and more effective in the estimation of both aspects of body composition (lean body mass and fat mass), than those of other researchers.

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