Michiko Suzuki

The isolation of metallothionein and its protective role in cadmium poisoning

Abstract People that have been subjected to cadmium poisoning show marked calcified tissue and kidney disturbances. In rats fed a cadmium-containing, low-calcium-vitamin D-deficient diet, the major portion of the cadmium accumulated in the liver and kidneys. Despite the fact that only a small amount (2.8 ppm) of cadmium completely inhibits the in vitro enzymic 1-hydroxylation reaction of 25-hydroxycholecalciferol, the in vivo 1-hydroxylation proceeded without appreciable inhibition even in the rats loaded with large amounts of oral cadmium. No light-microscopic morphological changes could be found in the kidneys of cadmium-fed rats. Most of the cadmium that accumulated in the kidneys was in a form bound to the protein, metallothionein, and therefore was not toxic to that organ. On the other hand, only 20% of the cadmium present in bone appears to be protein bound. The data strongly suggest that the protective effect of metallothionein in the kidney is serendipitous when involved in cadmium poisoning and that cadmium ion acts directly on bone rather than by an indirect action through a functional disturbance of the kidney.

Complete amino acid sequence of amelogenin in developing bovine enamel

Pure amelogenin protein in developing bovine incisor enamel was isolated and its primary structure was investigated by sequencing the peptides obtained after clostripain and chymotrypsin digestions and CNBr degradation with an automated Edman sequencer. The enamel protein was found to be composed of 170 amino acid residues with one phosphate having a molecular weight of 19,350 and its complete amino acid sequence was elucidated. This protein has no sequence homology with any other tissue or secretory protein of known structure.

Cyclical changes in pH in bovine developing enamel as sequential bands

Developing enamel was stained with pH indicators and a banded colour pattern exhibiting alternate acidic (5.8-6.0) and neutral (7.0-7.2) staining was clearly visualized. The pH values of the enamel samples scraped from respective bands were confirmed by measuring them in suspensions with a pH meter. Neutral bands corresponded to red stripes of glyoxal bis(2-hydroxyanil) staining and acidic bands to unstained ones, suggested a correlation of the acidic and neutral stripes with the zones of ruffle-ended and smooth-ended ameloblasts.

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.

Synthesis and biological activity of 1α-hydroxyvitamin D3

Abstract Hydroboration of cholesta-1,5-diene-3β-ol followed by alkaline-peroxide oxidation resulted in the formation of 1α- and 2α-hydroxy derivatives of cholesterol in nearly equal amounts. 1α-Hydroxycholesterol was then transformed to 1α-hydroxyvitamin D 3 , via 1α-hydroxycholest-5,7-diene-3β-ol. 1α-Hydroxyvitamin D 3 was as active as 25-hydroxyvitamin D 3 in the stimulation of intestinal calcium transport and bone mineral mobilization in intact rats, and moreover was able to produce both response in anephric rats similar to 1α,25-dihydroxyvitamin D 3 , the active metabolite of vitamin D 3 , as reported originally by DeLucas group.

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.

25-hydroxylation of 1α-hydroxyvitamin D3 in vivo and in perfused rat liver

The demonstration that la-hydroxyvitamin D3 (la-OH-Ds) can replace the metabolically active form of vitamin Ds, lcy,25dihydroxyvitamin Ds (la,25(OH)z-Ds) in the treatment of various vitamin D refractory syndromes [l-3] has prompted investigations on the metabolism of this analog. In 1975, we synthesized [2-3H]-1~-OH-D3 and demonstrated that if was metabolized very rapidly to [3H]-lar,25-(OH)zD3 in perfused rat liver [4]. [3H]-1a,25-(OH)Z-D3 was found to be the only metabolite of [3H]-lcu-OHD3 produced by the liver [4]. Almost simultaneously, Holick et al. synthesized [6-3H]-la-OH-D3 and reached the same conclusion from in vivo studies in rats [5] . This paper reports in vivo and liver perfusion studies showing that 25-hydroxylation of l&OH-D3 by the liver is not under metabolic control.