ANALYSES OF H*(10) DOSE RATES MEASURED IN ENVIRONMENT CONTAMINATED BY RADIOACTIVE CAESIUM: CORRECTION OF DIRECTIONAL DEPENDENCE OF SCINTILLATION DETECTORS

Ambient dose equivalent rates were measured in the environment of the Fukushima prefecture using NaI(Tl)/CsI(Tl) scintillation detectors and CdZnTe/Ge semiconductor detectors. The dose rates obtained at the same locations varied beyond uncertainty (1σ). By replacing the spectrum-dose conversion operators obtained from the anterior-posterior geometry with those from the rotational geometry, the dose rates agreed with each other within uncertainties, except for a CsI(Tl) scintillation detector with a considerably flat crystal configuration, due to its excessive directional dependence.

FT-NMR Detection of 45Sc, 49Ti and 93Nb in TiO2 Single Crystal

In order to determine the electric quadrupole moment of the short-lived β-emitter 41Sc from the quadrupole coupling constant in TiO2 , we measured the field gradient by detecting the Fourier-Transformed-NMR of stable isotope 45Sc doped in TiO2. Also, in order to study the electronic structure of impurities systematically, EFGs were measured for 45Sc, 49Ti and 93Nb in a TiO2 ingle single crystal.

[Family make-up is associated with the admission rate of stroke patients--difference between Kochi and Shimane Prefectures and in a rural community]

Kochi Prefecture had a higher admission rate for patients with cardiovascular disease, particularly for stroke, than Shimane Prefecture which has a similar socio-economic level. Kochi Prefecture had a smaller average number of persons in a household, a lower proportion of three generation households, and a lower proportion of households with six persons or more than Shimane Prefecture. The decline in number of persons in a household was greater in Kochi Prefecture than in Shimane Prefecture from 1960 to 1985, especially between 1970 and 1975. The association between family make-up and hospital discharge one year after stroke was examined in a rural community in Kochi Prefecture. Two hundred forty nine patients aged 40 years and older who were admitted immediately after stroke events were registered between 1969 and 1988, and they were followed for one year. According to family make-up, the subjects were divided into four groups: 1) persons who lived with spouse and daughter-in-law, 2) persons who lived with spouse, 3) persons who lived with daughter-in-law, 4) persons who lived without spouse and daughter-in-law. Although mean age and the proportion of serious cases were not different between group 1 and group 4, the proportion of admitted patients of group 1 was significantly lower than that of group 4. About 60% of group 1 had households with six persons or more. Group 2 had the lowest proportion of admitted patients, but this group was significantly younger than other groups. Within group 3, the proportion of admitted patients was higher in households in which the daughter-in-law had a job than in households in which she did not. These results suggest that the high admission rate in Kochi Prefecture is attributable to households which are short of personnel for home care.

[A nested case-control study of risk factors for intracerebral hemorrhage and cerebral infarction classified by computed tomographic findings]

Risk factors for intracerebral hemorrhage (ICH) and cerebral infarction (CI), were studied by a prospective study of 7,390 men and women aged 40-69 without a history of stroke living in three rural populations in Japan. Baseline examinations were done for populations in Akita-Ikawa and Akita-Ishizawa in 1975-1979, and for Ibaraki-Kyowa in 1981-1987, and followed until 1989 for Akita-Ikawa and Ibaraki-Kyowa and 1987 Akita-Ishizawa. There were 246 stroke cases diagnosed by clinical criteria during the follow-up period in which 74 percent (n = 181) had data from computed tomography (CT) performed within three weeks of the onset. According to these CT-findings, 181 stroke were classified as 48 with ICH, 50 with CI in penetrating artery regions (penetrating artery infarction), 33 with CI in cortical artery regions (cortical artery infarction), and 31 with subarachnoid hemorrhage while there were 19 with stroke without any evident CT abnormality. Cortical artery infarction was further classified as embolic type (n = 17) and thrombotic type (n = 9) according to clinical findings of the onset and presence of possible embolic sources such as atrial fibrillation, congenital heart disease, myocardial infarction and heart valve diseases. Using a nested case-control design, risk variables at baseline examination were compared between 131 stroke cases, 48 ICH and 83 CI, with 655 controls matched for sex, age (+/- 3), and the follow-up year. Univariate analysis showed that high blood pressure was associated with all types of stroke. From conditional logistic regression analysis significant risk variables were found to be high blood pressure for ICH and penetrating artery infarction, while atrial fibrillation and ST-T abnormality in electrocardiogram (ECG) were risk variables for cortical artery infarction. Associations with hypertensive or arteriosclerotic changes in ocular fundus were stronger for penetrating artery infarction than ICH and cortical artery infarction. ST-T abnormality in ECG was associated with embolic type cortical artery infarction and high blood pressure was associated with the thrombotic type, although the number of cases were small. Compared to controls, cortical artery infarction showed a higher mean value of serum total cholesterol for thrombotic type cortical infarction, and lower mean values for embolic type and ICH, but none of them reached statistical significance. The present study also suggests that duration of hypertension varied with type of stroke. ICH may develop due to acute effects of hypertension, while penetrating artery infarction and cortical artery infarction develop by chronic effects of hypertension.

[A population-based study of the proportion by type of stroke determined by computed tomography scan]

To investigate the proportion by type of stroke in communities, a stroke surveillance was conducted in three rural populations between 1979 and 1987. Among 411 stroke patients aged 40 and over determined by the modified Millikan's stroke criteria, the type of stroke was analyzed using computed tomography (CT) criteria for 273 patients who were examined by CT. 1. Incidence rates of stroke determined by the modified Millikan's criteria did not vary among the three populations in all age-sex groups except for men aged 60-69. 2. The proportion of stroke patients who had CT examinations was 84-88% for men and women aged 40-69 in the three communities. 3. According to the CT criteria, the proportion by type of stroke in patients aged 40-69 in the three communities was 32% for cerebral hemorrhage, 16% for subarachnoid hemorrhage, 42% for cerebral infarction and 10% for unspecified stroke without CT abnormalities. Among the total with cerebral infarction, the proportion with cerebral infarction in penetrating artery regions, mostly lacunar infarction, was 65% and that of infarction in cortical artery regions, mostly thromboembolic infarction, was 35% for patients aged 40-69. 4. Cerebral infarction in cortical artery regions was classified further into embolic, thrombotic and unspecified types based on CT findings, the presence of embolic origin, and symptoms at the onset. The proportion of these three types of infarction were similar in patients aged 40-69. Compared with hospital-based studies in Japan, the present population-based study showed a higher proportion of cerebral infarction and infarction in penetrating artery regions. This study also indicated that the proportion of cerebral hemorrhage and infarction in penetrating artery regions was higher and that of infarction in cortical artery regions lower in Japanese than in Caucasians.

[A community-based education program for serum cholesterol reduction in urban hypercholesterolemic persons--comparison of intensive and usual education groups]

A community-based education program was conducted for persons found to be hypercholesterolemic by screening during cardiovascular surveys, in an urban population, to evaluate the feasibility and effect of the program in primary prevention of coronary heart disease. The subjects were men and women aged 40-64 living in the suburbs of Osaka whose serum total cholesterol was between 240 and 299 mg/dl in both the 1988 and the 1989 surveys. Persons with hypothyroidism, those taking medication for hypercholesterolemia or hypertension, and with a history of stroke and coronary heart disease were excluded. Of the 111 persons who were eligible, 104 persons were recruited for the program on March, 1989. The 104 persons were randomly assigned to either an intensive education group (n = 51) or a usual education group (n = 53). For the intensive education group, seven education classes were held from April to November, 1989. Lectures, practice sessions, interviews, and spot cholesterol measurements were conducted in a local community center. The usual education group received a letter with results from the 1989 survey and dietary instruction in April 1989 and an education class in September 1989. Mean serum cholesterol in the intensive education group showed a 10.0 mg/dl greater reduction in September 1989 and a 9.0 mg/dl greater reduction in March 1990 than in the usual education group (p less than 0.05) while mean HDL-cholesterol did not change in either groups. The intensive education group reported a larger decrease in the dietary frequency of chicken egg, poultry skin and small fishes, foods which are rich in saturated fat and cholesterol. The frequency of fatty meat, butter and fish eggs was low in both groups and did not differ between the two groups after the one-year program. These results indicate that a population-based education program is feasible and effective in reducing serum total cholesterol of hypercholesterolemic persons.

Calcium intake and blood pressure in seven Japanese populations

The relation between dietary calcium and blood pressure was examined in 1,928 men, ages 40-69 years, from five geographic and two occupational populations in Japan. Dietary calcium intake was estimated using 24-hour dietary recall in systematic samples of participants of population-based cardiovascular surveys from 1983 to 1987. The means of daily calcium intake of the study populations ranged from 449 to 695 mg, approximately 300 mg lower than the recommended US dietary calcium intake. Linear regression analyses were used to examine the relation between dietary calcium and blood pressure within each population, controlling for age, body mass index, alcohol consumption, and sodium intake. Total calcium intake was inversely associated with the systolic blood pressure level in each population, and the pooled estimate of the regression coefficients for millimeters of mercury of blood pressure per 100-mg increase in calcium intake was -0.54 (95% confidence interval -0.89 to -0.19). The inverse association between calcium intake and diastolic blood pressure was less consistent, and the pooled estimate did not reach statistical significance (-0.10, 95% confidence interval -0.34-0.14). Inverse associations existed for both dairy and nondairy food sources of calcium when analyzed separately, and the association was significant only for dairy calcium. Although a causal relation between dietary calcium and blood pressure cannot be established, these results suggest a possible public health implication in Japan of increasing calcium intake for the prevention and control of hypertension, where average dietary calcium intake is low.

[Secular trends in prevalence and incidence of atrial fibrillation and associated factors in a Japanese rural population]

To investigate secular trends in prevalence and incidence of atrial fibrillation and associated factors, data from population studies of a northeast rural Japanese community, were explored. Cross-sectional studies for men and women aged 40-69 year were conducted in 1963-1966, 1972-1975 and 1984-1987. Age-adjusted prevalence rates of atrial fibrillation show no significant change in both men and women during these three periods. Over 80% of atrial fibrillation in each period showed no clinical evidence of rheumatic valvular disease, myocardial infarction, idiopathic cardiomyopathy, congenital heart disease and hyperthyroidism. Cohorts of men and women aged 40-69 year without atrial fibrillation at baseline were constructed in 1963-1966 (1,920 persons) and in 1972-1975 (2,325 persons) and followed until 1974 and 1987, respectively. In both cohorts, incidence of atrial fibrillation without these organic diseases was positively associated with hypertension related funduscopic abnormality and urine protein. Age-adjusted incidence rates of atrial fibrillation declined in both men and women between the two cohorts. This decline which was greater in hypertensives than in normotensives may in part reflect improvements in hypertension control in this community.

Alcohol intake and hypertension among urban and rural Japanese populations

A significant positive relationship was found between alcohol intake and blood pressure for men 40-69 years old living in urban Osaka (492 men) and in rural Akita (395 men), Japan, surveyed from 1975 to 1977. Both mean blood pressure and the prevalence of hypertension were related to alcohol intake in a graded fashion. Stepwise multiple regression also showed that both systolic and diastolic pressure were associated with alcohol intake independent of ponderosity index, serum cholesterol, triglycerides, hemoglobin, uric acid, smoking, and age. This cross-sectional study indicates a continuous--and not a threshold--relationship between alcohol and blood pressure, with the effect of even moderate consumption, e.g. 28-55 g per day (equivalent to about 2-4 U.S. drinks per day).

Dietary intake and serum total cholesterol level: their relationship to different lifestyles in several Japanese populations

Serum total cholesterol level and dietary intake were surveyed 1975--1977 in six Japanese population groups with different lifestyles, including groups in both rural (Akita and Kochi) and urban (Osaka) areas. Clerical workers in Osaka, who had the most westernized lifestyle of all the study groups, had the highest mean serum total cholesterol level (202 mg/dl for men ages 40--49 and 50--59 years), while farmers in Akita had the lowest mean serum total cholesterol level (163 mg/dl for men 40--49 years old, 159 mg/dl for men 50--59 years old, 165 mg/dl for men 60--69 years old). Nutrient intake data for mean ages 40--59 years showed 23% of calories from fat for clerical workers in Osaka, the highest among the study groups, whereas farmers in Akita showed a low level of 14%. The ratio of dietary polyunsaturated to saturated fatty acids was over 1.1 for all groups. Cholesterol intake was 339--487 mg/day. Total carbohydrate as a percentage of calories was 53--65%; 75--80% of carbohydrate energy was ingested from cereals. Sugar accounted for less than 3.5% of total calories. In the cross-group correlation analysis between dietary lipid intake and serum total cholesterol, a significant strong positive correlation was found between the dietary lipid factor (phi) of Keys et al. and the mean serum total cholesterol level. A weak but significant correlation was observed between the dietary lipid factor and serum total cholesterol for individual inhabitants of Osaka.

Serum total cholesterol, triglyceride level, and dietary intake in Japanese students aged 15 years

The authors surveyed serum cholesterol and triglyceride levels in 238 male and 217 female students aged 15 years in Osaka, Japan, in 1977, as well as dietary intake, using a 24-hour record in 81 male and 61 female students. Serum cholesterol and triglyceride levels of Japanese students were 163.6 mg/dl and 81.7 mg/dl, respectively, for males, and 182.2 mg/dl and 78.9 mg/dl for females. For female students, those who participated in a school sports club regularly during the previous three years had cholesterol levels 10 mg/dl lower than the subjects who had not participated in a sports club; these active students also had smaller skinfold thickness, although there was no difference in other anthropometric measurements. Although the dietary intake of Japanese students was found to be westernized, compared with that of Japanese adults, Japanese students reported low fat intake (25-30% of energy), high polyunsaturated/saturated fatty acid ratio (1.1-1.2), and high carbohydrate intake (55-61% of energy), differing considerably from US students.

Multivariate analysis of risk factors for stroke. Eight-year follow-up study of farming villages in Akita, Japan

Akita Prefecture has an especially high mortality rate from stroke, and its age-adjusted death rate from stroke is the highest in Japan. We have carried out an epidemiological survey of cardio- and cerebrovascular diseases (CVD) in farming villages in this prefecture since 1963, with a response rate of 84%. During our 8-year follow-up, 94 new stroke cases were observed among 1,814 subjects. Multiple logistic function analysis was carried out on nonstroke and stroke cases from subjects aged 40 to 69 years at time of initial examination, in order to clarify the risk factors for stroke. The analysis used eight variables: age, sex, systolic blood pressure, obesity index, urinary sugar, urinary protein, serum total cholesterol, and total protein. The results showed that hypertension was the most important risk factor for stroke. However, regarding cholesterol, multivariate analysis showed that among men and women aged 40 to 69 years at entry, subjects with low serum total cholesterol levels were more prone to cerebral hemorrhage, but that serum cholesterol level had no weight as a risk factor for cerebral infarction. These results correspond well with the observed fact that stroke incidence or death rate in Japan is higher in populations with high prevalence of hypertension and low concentration of cholesterol, and also with the fact that death rate from hemorrhage declines with the increment of serum total cholesterol and the westernization of diet.

Laser flash method for measuring thermal conductivity of liquids-application to low thermal conductivity liquids

A laser flash method developed for the measurement of thermal conductivity of solids was applied to liquids of low thermal conductivity. The sample liquid was sandwiched in between a small thin metal disk and a sample holder. When the laser beam is absorbed in the front surface of the metal disk, the temperature of the disk quickly rises about 2 K and heat then flows downwards through the sample liquid as one-dimensional heat flow. The thermal conductivity of liquid can be obtained from the temperature fall of the disk without employing any reference materials and also without measuring the thickness of the sample liquid layer. Thermal conductivities of water and toluene near room temperature were measured by this method with a mean deviation of 2.6%. This laser flash method may be applied to the measurement of the thermal conductivity of liquids such as molten salts at elevated temperatures.