Hirofumi Kitaoka

Aldosterone synthase gene (CYP11B2) C-334T polymorphism, ambulatory blood pressure and nocturnal decline in blood pressure in the general Japanese population: the Ohasama Study.

Objective The C-344T polymorphism in the 5′-flanking region of the aldosterone synthase (CYP11B2) gene has been suggested to be associated with hypertension and disturbed circadian blood pressure (BP) rhythm through its effect on aldosterone synthesis. However, previous findings on this topic have been inconsistent. Design A cross-sectional study. Subjects and methods We investigated the CYP11B2 C-344T genotype in 802 subjects, aged 40 and over, in a Japanese community, who gave written informed consent and were monitored for 24 h ambulatory BP. Results The frequencies of the CC, CT, and TT genotypes in these Japanese subjects were 0.14, 0.44, and 0.42, showing a higher frequency of the T allele (0.64) than in Caucasians. Although there was no significant difference in 24 h ambulatory BP levels among the genotypes, the nocturnal decline in BP was significantly greater in the CC homozygous subjects than in other subjects (P = 0.0065 for systolic and P = 0.031 for diastolic decline in nocturnal BP). Detailed analyses demonstrated that this association was significant only in aged (60 years and over) or male subjects. The prevalence of previous cardiovascular disease was significantly less in these subjects with the CC genotype than in those with the TC and TT genotypes, although age, body mass index, male gender, smoking, use of alcohol and antihypertensive medication did not differ among the three genotypes. There was no significant difference among the three genotypes in biochemical and hormonal parameters. Conclusion Although the C-344 T polymorphism of CYP11B2 did not directly influence the level of 24 h BP, the CC genotype was associated with decreased nocturnal BP in elderly or male Japanese. Since prevalence of previous cardiovascular disease was significantly less in homozygous CC subjects, greater nocturnal BP decline in this genotype appears to be beneficial in the circadian BP rhythm.

Predictive values of automated blood pressure measurement: what can we learn from the Japanese population - the Ohasama study.

BackgroundMeasurements of ambulatory blood pressure (ABP) and of home blood pressure (HBP) as an adjunct to casual/clinic blood pressure (CBP) measurements are currently widely used for the diagnosis and treatment of hypertension. We have monitored a rural cohort of people from the population of Ohasama, Japan, with respect to their prognosis and have previously reported that ABP and HBP are superior to CBP for the prediction of cardiovascular mortality. One reason that CBP is a poor predictor of prognosis is that it incorporates several biases, including the white-coat effect. Methods and resultsWe examined the prognostic significance of white-coat hypertension for mortality and found that the relative hazard for the overall mortality of patients with white-coat hypertension was significantly lower than that for true hypertension. Short-term blood pressure variability has recently attracted attention as a cause of target-organ damage and cardiovascular complications. Our results confirmed that short-term blood pressure variability (as measured every 30 min) was independently associated with cardiovascular mortality. In addition, research has recently focused on isolated systolic hypertension and pulse pressure as independent risk factors for poor cardiovascular prognosis. The Ohasama study also clearly demonstrated that isolated systolic hypertension and increased pulse pressure, as assessed by HBP, were associated with an increase in the risk of cardiovascular mortality. Circadian blood pressure variation is characterized by a diurnal elevation and a nocturnal decline in blood pressure. We therefore compared morbidity from stroke between dippers (subjects who show an ordinal nocturnal dipping of blood pressure) and non-dippers (those with a diminished nocturnal dipping or nocturnal elevation of blood pressure [inverted dippers]) in the Ohasama study. The incidence of stroke increased with an increased length of observation in dippers using antihypertensive medication but not in non-dippers using antihypertensive medication. In contrast, the relative hazard for mortality increased in non-dippers and inverted dippers. These results suggest a cause-and-effect relationship for both dippers and non-dippers. ConclusionThe Ohasama study showed that the level and variability of hypertension as assessed by ABP and HBP are independent predictors of cardiovascular mortality. It also demonstrated an independent association between the prognosis of hypertension and each component of ABP and HBP, indicating the prognostic significance of these blood pressure measurements.

Relationship between personality and self-measured blood pressure value at home: the Ohasama study.

We conducted a cross-sectional community survey in northern Japan to assess the relationship between personality and home blood pressure value. The Japanese version of the short-form Eysenck personality questionnaire was used to assess personality. A total of 999 people selected from the general population participated. We showed that the personality extroversion score positively affected the systolic blood pressure value, whereas no significant relationship was observed between personality psychoticism or neuroticism and blood pressure value. This study is the first to clarify the relationship between personality assessed by the Eysenck personality questionnaire and blood pressure measured in a non-medical setting. When physicians investigate the pathogenesis of essential hypertension, they should take psychological factors into consideration, as well as the many environmental and genetic factors.

[Free thyroxine estimation for screening of hyper- and hypothyroidism in an adult population].

Serum free thyroxine (FT4) was determined in 1,114 adults (male 239, female 875) in a periodic health evaluation in 1980 to detect unsuspected thyroid dysfunction, especially hyper- and hypothyroidism. The participants were dwelling in two towns of Miyagi prefecture. Beside FT4, serum T4 and T3 were also determined by radioimmunoassay. If thyroid dysfunction was suspected, further detailed examinations such as TRH-test (500 micrograms i.v.), radioimmunologic determinations of serum TSH and TBG, resin-sponge T3-uptake, 24-hr thyroid radioiodine 131I-uptake, radioiodine thyroid scan and anti-thyroid antibodies were performed. There were 3 patients with hyperthyroidism (0.27%), 4 with hypothyroidism (0.36%), 3 taking thyroid medication (2; Hashimotos disease, 1; goiter), 3 on estrogen administration, 4 with Hashimotos disease and 1 with goiter. Excluding these 18 patients, FT4, T4 and T3 values in 1,096 euthyroid subjects, 236 males and 860 females, were 1.1 +/- 0.3 (mean +/- S.D.), 1.1 +/- 0.3 and 1.0 +/- 0.3 ng/100 ml, 8.9 +/- 1.5, 8.8 +/- 1.6 and 9.0 +/- 1.5 micrograms/100 ml, and 122 +/- 33, 125 +/- 26 and 122 +/- 35 ng/100 ml, respectively. Serum FT4, T4 and T3 showed the distribution of logarithmic normal probability. The 95% normal range for free T4 was 0.60 to 1.80 ng/100 ml, total T4 6.0 to 11.8 micrograms/100 ml, and T3 84 to 176 ng/100 ml, respectively. Out of 1,114 subjects examined, the cases to be reexamined for the higher serum concentration than normal were 26 in FT4, 35 in T4 and 27 in T3, respectively. And the cases for lower values were 28 in FT4, 31 in T4 and 24 in T3, respectively. Serum FT4 values in the subjects during the administration of estrogens were within the normal range. FT4 and T4 were low in four patients with hypothyroidism, but two of them showed normal T3 values. Determinations of serum FT4, total T4 and total T3 were all useful for the screening of hyperthyroidism. But serum FT4 was the most reliable of the three. Determination of either serum FT4 or total T4 was suitable for the screening of hypothyroidism, but serum total T3 measurement did not cover all patients with hypothyroidism.