Tohru Fujiwara

Device for the self-measurement of blood pressure that can monitor blood pressure during sleep.

Sponsorship: This work was supported by Research Grants from the Takeda Medical Foundation, the Japan Arteriosclerosis Prevention Fund ( ) ( ) JAPF, 2000 and the Mitsui Life Social Welfare Foundation 1998 , by Research Grants of Kosei Kagaku Kenkyuhi, 1996 and 1997, of Junkankibyo ( ) Itaku Kenkyuu 11C-5 , 1999, and Rojin Hoken Jigyo, 1998 and 1999, from the Ministry of Health and Welfare, and by a Research Grant for Scientific ( ) ( ) Research 10470102 and a Research Grant for JSPS’ Research T.O. from the Ministry of Education, Science and Culture of Japan.

Insufficient duration of action of antihypertensive drugs mediates high blood pressure in the morning in hypertensive population: the Ohasama study.

Blood pressure (BP) usually peaks in the morning. The circadian variation of the onset of cardiovascular disease mimics this circadian BP variation. To examine the determinants of the BP difference between the self-recorded BP in the morning (home BP) and daytime average ambulatory BP a cross sectional study was done in the general population of Ohasama, Japan. 1207 subjects ≥20 years measured both home (more than 14 times) and ambulatory BPs (326 treated for hypertension and 881 untreated subjects). The prevalence of subjects with the systolic BP difference (home BP in the morning−daytime ambulatory BP) of ≥10 mmHg (high morning BP) was 5.6% in untreated normotensives, 2.9% in untreated hypertensives, and 25.8% in treated hypertensives. This trend was also observed for diastolic pressure. Multiple regression analysis demonstrated that age, male sex, and use of antihypertensive drugs were positively associated and day-night difference of BP was negatively associated with the high morning BP, respectively. These results suggest an insufficient duration of antihypertensive action of widely used antihypertensive drugs in Japan from the 1980s to 1990s. The amplitude of the day-night difference of ambulatory BP in subjects with a high morning BP was lower (non-dipping) than that without high morning BP. The high morning BP is not necessarily accompanied by hypertension but might be mediated, at least in part, by an insufficient duration of action of antihypertensive drugs. The high morning BP accompanies so-called non-dipper pattern of circadian BP variation. An insufficient duration of action of drugs may partly mediate non-dipping in subjects with antihypertensive medication.

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.

Angiotensin converting enzyme I/D polymorphism and hypertension : the Ohasama study

Objective Angiotensin-converting enzyme (ACE) I/D polymorphism in intron 16 of the ACE gene was analyzed in a general Japanese population in relation to self-blood pressure (BP) measurement at home (home BP) and ambulatory BP monitoring (ABPM) to determine the association between genetic variants of this polymorphism and hypertension. Design A cross-sectional study. Methods and results We genotyped the ACE I/D polymorphism in 1245 subjects with home BP and 803 subjects with ABPM in Ohasama, a rural community in Japan. All the subjects were 40 years of age and over, and gave written informed consent for the present genetic analysis. Hypertensive subjects were defined as those receiving antihypertensive drugs and those who had a home BP higher than 135 mmHg in systole and/or higher than 85 mmHg in diastole. The frequencies of the II, ID, and DD genotypes in these Japanese subjects were 0.45, 0.45, and 0.10, indicating a lower frequency of the D allele (0.33) than in Caucasians. There was no significant difference of BP level, prevalence of hypertension or nocturnal decline in BP among the genotypes. There were no differences in the prevalence of previous cardiovascular disease, age, body mass index, male gender, smoking, or biochemical and hormonal parameters among the three genotypes. Conclusion The present results indicate the absence of direct effects of the ACE D-allele on BP level, prevalence of hypertension, prevalence of cardiovascular disease, and circadian BP variation. We conclude there is little association between ACE I/D polymorphism and hypertension in the general Japanese population.

Rationale and design of Homed-bp Study: Hypertension Objective treatment based on Measurement by Electrical Devices of Blood Pressure Study

BackgroundHow far should blood pressure (BP) be lowered to achieve the greatest reduction in the risk of cardiovascular disease? Although a few trials have tried to answer this question, they failed to convincingly establish an optimal target BP level, in part because of poor reproducibility and the wide variability of conventional casual BP measurement they used. At the same time, in Japan, calcium antagonist (Ca-A) and angiotensin-converting enzyme inhibitor (ACE-I) have been two major medications in initial therapy for hypertension, while angiotensin II receptor antagonist (ARB), which has recently been introduced, is also now used widely as an initial therapy. However, no large-scale interventional trial has been conducted to show which of these three initial medications can give the greatest benefit in reducing the risk of cardiovascular disease in the Japanese hypertensive patient. ObjectiveThe objectives of the study are, first, to determine an optimal target BP level, based on BP values self-measured at home (home BP). This way of measurement provides more reproducible and less variable BP values than conventional casual measurements. Secondly, we seek to determine the optimal initial antihypertensive medication for the Japanese hypertensive population. MethodThe study is a 2×3 factorial randomized controlled trial conducted with a prospective randomized open-blinded endpoint design. The study will include a total of 9000 untreated essential hypertensive patients aged 40 to 78 years with home BP values ≥135/85 mmHg. Eligible patients are randomized to one of the two home BP target groups (systolic/diastolic home BP within the range of 134–125/84–80 mmHg, or ≥125/80 mmHg), and to regimens based on one of three initial antihypertensive drugs (Ca-A or ACE-I or ARB). These randomizations, performed by our host computer, are transmitted to terminals at the outpatient clinic through the Internet. The patient measures BP at home with newly developed equipment (HEM-7471C-N; Omron, Japan) that records BP values, the date, and the time of each measurement. The data are downloaded to the outpatient terminal at every clinic visit then transmitted to the host computer via the Internet. Based on these home BP values, the host computer determines the necessity of additional therapy or dose increments in four further steps to reach the randomized target BP, and then transmits the information to the terminal at the outpatient clinic. The primary study outcome is a composite of non-fatal stroke, non-fatal myocardial infarction, and cardiovascular death. The scheduled average post-randomization duration of follow-up is 7 years. ConclusionThis is the first large-scale home BP-based and Internet-connected intervention trial on antihypertensive treatment. The HOMED-BP study (Hypertension Objective treatment based on Measurement by Electrical Devices of BP) will improve the recruitment of general practitioners and participants and will supply unbiased BP data, providing reliable information on optimal target BP levels and the optimal initial antihypertensive medication.

Identification of a novel erythroid-specific enhancer for the ALAS2 gene and its loss-of-function mutation which is associated with congenital sideroblastic anemia

Erythroid-specific 5-aminolevulinate synthase (ALAS2) is the rate-limiting enzyme for heme biosynthesis in erythroid cells, and a missense mutation of the ALAS2 gene is associated with congenital sideroblastic anemia. However, the gene responsible for this form of anemia remains unclear in about 40% of patients. Here, we identify a novel erythroid-specific enhancer of 130 base pairs in the first intron of the ALAS2 gene. The newly identified enhancer contains a cis-acting element that is bound by the erythroid-specific transcription factor GATA1, as confirmed by chromatin immunoprecipitation analysis in vivo and by electrophoretic mobility shift assay in vitro. A promoter activity assay in K562 human erythroleukemia cells revealed that the presence of this 130-base pair region increased the promoter activity of the ALAS2 gene by 10–15-fold. Importantly, two mutations, each of which disrupts the GATA-binding site in the enhancer, were identified in unrelated male patients with congenital sideroblastic anemia, and the lower expression level of ALAS2 mRNA in bone marrow erythroblasts was confirmed in one of these patients. Moreover, GATA1 failed to bind to each mutant sequence at the GATA-binding site, and each mutation abolished the enhancer function on ALAS2 promoter activity in K562 cells. Thus, a mutation at the GATA-binding site in this enhancer may cause congenital sideroblastic anemia. These results suggest that the newly identified intronic enhancer is essential for the expression of the ALAS2 gene in erythroid cells. We propose that the 130-base pair enhancer region located in the first intron of the ALAS2 gene should be examined in patients with congenital sideroblastic anemia in whom the gene responsible is unknown.

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.

Genotypes of the βENaC gene have little influence on blood pressure level in the Japanese population

The gene for the beta-subunit of the epithelial sodium channel (betaENaC) is one of the most prominent candidate genes being analyzed for an association with human essential hypertension. It is known that a deletion or alteration of PY motif in exon 12 of betaENaC is responsible for Liddles syndrome. Although the localization of genetic polymorphisms of betaENaC is unique to each population, intensive analysis of individuals of white and African ancestry has demonstrated that genetic variants are localized in exons 8 and 12, with two frequent polymorphisms, G442V in exon 8 and T594M in exon 12. These two mutations are both found in individuals of African ancestry, and might be associated with elevated blood pressure (BP). Previously, we have screened the last two-thirds of exon 12 in the Japanese population, and demonstrated the absence of the T594M mutation and the presence of a novel P592S mutation. In the present study, we further examined the rest of exon 12 and exon 8 in a general population from Ohasama, Japan (the Ohasama Study), using single-strand conformational polymorphism (SSCP) analysis. We screened 803 subjects randomly selected from the representative participants, who measured their home and casual BP. The PCR products presenting a shift in SSCP gels, as well as controls, were directly sequenced by autoanalyzer to identify the mutation. A novel gel shift was noted in exon 12 (n = 8) and sequencing identified a polymorphism at codon Ser 520, leading to no change in amino acid sequence (G77576C TCG-->TCC). In exon 8, all three SSCP variants were heterogynous for V434M (GTG-->ATG), which is coincident with a rare polymorphism in whites. The G442V mutation, however, was absent from the Japanese population. A novel mutation of exon 12 was not associated with a significant difference in clinical features. These results indicate that Japanese people possess three polymorphisms in exon 12, all of which are unique, and one in exon 8. These genetic variants of betaENaC may not influence the BP level of Japanese people.

3-Deazaneplanocin A (DZNep), an inhibitor of S-adenosylmethionine-dependent methyltransferase, promotes erythroid differentiation.

Background: S-adenosylmethionine-dependent methyltransferase inhibitor, DZNep, targets the degradation of histone methyltransferase EZH2 that catalyzes H3K27 trimethylation. Results: DZNep induced erythroid-related genes, which may not be directly related to EZH2 inhibition but may be partly associated with reduced protein level of hematopoietic corepressor ETO2. Conclusion: DZNep has the capacity to induce erythroid differentiation. Significance: Our data may be exploited for therapeutic applications for hematological diseases, including anemia. EZH2, a core component of polycomb repressive complex 2 (PRC2), plays a role in transcriptional repression through histone H3 Lys-27 trimethylation and is involved in various biological processes, including hematopoiesis. It is well known that 3-deazaneplanocin A (DZNep), an inhibitor of S-adenosylmethionine-dependent methyltransferase that targets the degradation of EZH2, preferentially induces apoptosis in various hematological malignancies, suggesting that EZH2 may be a new target for epigenetic treatment. Because PRC2 participates in epigenetic silencing of a subset of GATA-1 target genes during erythroid differentiation, inhibition of EZH2 may influence erythropoiesis. To explore this possibility, we evaluated the impact of DZNep on erythropoiesis. DZNep treatment significantly induced erythroid differentiation of K562 cells, as assessed by benzidine staining and quantitative RT-PCR analysis for representative erythroid-related genes, including globins. When we evaluated the effects of DZNep in human primary erythroblasts derived from cord blood CD34-positive cells, the treatment significantly induced erythroid-related genes, as observed in K562 cells, suggesting that DZNep induces erythroid differentiation. Unexpectedly, siRNA-mediated EZH2 knockdown had no significant effect on the expression of erythroid-related genes. Transcriptional profiling of DZNep-treated K562 cells revealed marked up-regulation of SLC4A1 and EPB42, previously reported as representative targets of the transcriptional corepressor ETO2. In addition, DZNep treatment reduced the protein level of ETO2. These data suggest that erythroid differentiation by DZNep may not be directly related to EZH2 inhibition but may be partly associated with reduced protein level of hematopoietic corepressor ETO2. These data provide a better understanding of the mechanism of action of DZNep, which may be exploited for therapeutic applications for hematological diseases, including anemia.

Pathophysiology and genetic mutations in congenital sideroblastic anemia.

Sideroblastic anemias are heterogeneous congenital and acquired disorders characterized by anemia and the presence of ringed sideroblasts in the bone marrow. Congenital sideroblastic anemia (CSA) is a rare disease caused by mutations of genes involved in heme biosynthesis, iron–sulfur [Fe‐S] cluster biosynthesis, and mitochondrial protein synthesis. The most common form is X‐linked sideroblastic anemia, due to mutations in the erythroid‐specific δ‐aminolevulinate synthase (ALAS2), which is the first enzyme of the heme biosynthesis pathway in erythroid cells. Other known etiologies include mutations in the erythroid specific mitochondrial transporter (SLC25A38), adenosine triphosphate (ATP) binding cassette B7 (ABCB7), glutaredoxin 5 (GLRX5), thiamine transporter SLC19A2, the RNA‐modifying enzyme pseudouridine synthase (PUS1), and mitochondrial tyrosyl‐tRNA synthase (YARS2), as well as mitochondrial DNA deletions. Due to its rarity, however, there have been few systematic pathophysiological and genetic investigations focusing on sideroblastic anemia. Therefore, a nationwide survey of sideroblastic anemia was conducted in Japan to investigate the epidemiology and pathogenesis of this disease. This review will cover the findings of this recent survey and summarize the current understanding of the pathophysiology and genetic mutations involved in CSA.