Biomedical subjects

Yoshiko Hara

Publications and source records attributed to Yoshiko Hara.

6 recordsLinked to original sources

PubMed2006

Functional expression of thiocyanate hydrolase is promoted by its activator protein, P15K.

Thiocyanate hydrolase (SCNase) is a cobalt-containing enzyme with a post-translationally modified cysteine ligand, gammaCys131-SO(2)H. When the SCNase alpha, beta and gamma subunits were expressed in Escherichia coli, the subunits assembled to form a hetero-dodecamer, (alphabetagamma)(4), like native SCNase but exhibited no catalytic activity. Metal analysis indicated that SCNase was expressed as an apo-form irrespective of the presence of cobalt in the medium. On the contrary, SCNase co-expressed with P15K, encoded just downstream of SCNase genes, in cobalt-enriched medium under the optimized condition (SCNase((+P15K))) possessed 0.86 Co atom/alphabetagamma trimer and exhibited 78% of the activity of native SCNase. SCNase((+P15K)) showed a UV-Vis absorption peak characteristic of the SCNase cobalt center. About 70% of SCNase((+P15K)) had the gammaCys131-SO(2)H modification. These results indicate that SCNase((+P15K)) is the active holo-SCNase. P15K is likely to promote the functional expression of SCNase probably by assisting the incorporation of cobalt ion.

Amino Acid Sequence↗

PubMed2005

Heavy photon states in photonic chains of resonantly coupled cavities with supermonodispersive microspheres.

We propose and demonstrate a "bottom-up" approach to constructing photonic structures for photon manipulation. Supermonodispersive polymer microspheres are used as building blocks and a size uniformity better than 0.05% could be obtained by sorting the spheres using spectroscopic methods. The spheres are positioned in a V groove on a silicon substrate and form a photonic chain with resonant coupling of the optical whispering-gallery modes. Photonic band modes are clearly observed in fluorescence and resonant scattering spectra, and an excellent agreement with a tight-binding model calculation is found. Heavy photon states and a group index as high as 40 are obtained.

Journal Article↗

PubMed2004

Aldosterone antagonist facilitates the cardioprotective effects of angiotensin receptor blockers in hypertensive rats.

BACKGROUND: There is increasing evidence to support the importance of blocking aldosterone to prevent target-organ damage in hypertension. We recently demonstrated an aldosterone breakthrough phenomenon during administration of an angiotensin type 1 receptor blocker (ARB). OBJECTIVE: To elucidate the pathophysiological significance of residual aldosterone by investigating the influence of the aldosterone antagonist on the cardioprotective effects of the ARB in hypertensive rats. METHODS: Injection vehicle alone, ARB (1.0 mg/kg per day candesartan by mouth), aldosterone antagonist (10 mg/kg per day spironolactone, subcutaneously), or combined treatment were administered to male stroke-prone spontaneously hypertensive rats for 24 weeks from the age of 4 weeks. Blood pressure, plasma angiotensin II and aldosterone concentrations, left ventricular weight, expression of type I and type III collagen mRNA, and histological findings were determined. RESULTS: In the ARB-treated group, aldosterone concentrations remained unchanged (1.10 +/- 0.20 nmol/l, compared with 1.17 +/- 0.46 nmol/l in the control group), whereas systolic blood pressure (178 +/- 9 mmHg), left ventricular weight (0.372 +/- 0.035 g/100 g body weight), expression of collagen mRNA, and cardiac interstitial and perivascular fibrosis all decreased significantly compared with the control group (systolic blood pressure: 222 +/- 10 mmHg, P < 0.05; left ventricular weight: 0.483 +/- 0.021 g/100 g body weight, P < 0.05). Although blood pressure (217 +/- 9 mmHg) and left ventricular weight (0.467 +/- 0.027 g/100 g body weight) remained unchanged in the group receiving spironolactone, the expression of both types of collagen mRNA and cardiac interstitial and perivascular fibrosis showed a significant decrease compared with the vehicle-treated group. In the rats receiving combined treatment with the ARB and spironolactone, left ventricular weight (0.352 +/- 0.005 g/100 g body weight, P < 0.05), expression of collagen mRNA, and cardiac interstitial and perivascular fibrosis all showed a further improvement compared with both the ARB and spironolactone groups. CONCLUSIONS: These results demonstrate that residual aldosterone has a significant impact on target-organ damage in hypertension, even during chronic administration of an ARB. The addition of an aldosterone antagonist has an advantage in facilitating the cardioprotective effects of ARBs.

Aldosterone↗

PubMed2004

Effects of AT1 receptor antagonist and spironolactone on cardiac expression of ET-1 mRNA in SHR-SP/Izm.

Angiotensin II stimulates and angiotensin-converting enzyme inhibitor decreases endothelin-1 expression. Effects of the angiotensin-type 1 antagonist (angiotensin receptor blocker) on tissue expression of endothelin-1 in hypertension remained unknown. We investigated the effects of angiotensin-type 1 antagonist with and without co-administration of the aldosterone receptor antagonist spironolactone on cardiac expression of endothelin-1 mRNA. Angiotensin receptor blocker (candesartan, 1.0 mg/kg per day) was orally administered to male spontaneously hypertensive stroke-prone rats/Izm from 4 weeks of age for 4 weeks, 12 weeks and 28 weeks (angiotensin receptor blocker group). Lowdose spironolactone (10 mg/kg per day, s.c.), which does not affect blood pressure, was co-administered with angiotensin-type 1 antagonist for 28 weeks (angiotensin-type 1 antagonist + spironolactone group). Cardiac expression of endothelin-1 mRNA was determined. In the angiotensin receptor blocker group, although cardiac expression of endothelin-1 mRNA was significantly decreased after 4 weeks of treatment, it was significantly increased after 12 weeks and 28 weeks of treatment. In the angiotensin receptor blocker + spironolactone group, while systolic blood pressure did not show a further decrease from that in the angiotensin receptor blocker group, cardiac expression of endothelin-1 mRNA was decreased to the level in the untreated group. These results suggest that effects on endothelin-1 expression could modify the cardioprotective effects of angiotensin receptor blocker. Coadministration of angiotensin receptor blocker with low-dose spironolactone is recommended for further cardioprotection via suppression of endothelin-1 expression.

Administration, Oral↗

PubMed2004

Apolipoprotein E phenotype affects the malondialdehyde-modified LDL concentration and forearm endothelial function in postmenopausal women.

OBJECTIVE: We investigated whether the apolipoprotein E (apo E) phenotype affects the serum concentration of malondialdehyde-modified low-density lipoprotein (MDA-LDL) or forearm endothelial function in postmenopausal women. PATIENTS AND MEASUREMENTS: Individuals were divided into three groups according to their apo E phenotype: E2 (E2/2 and E2/3, n = 12); E3 (E3/3, n = 71); and E4 (E3/4 and E4/4, n = 27). The serum concentrations of lipids and MDA-LDL were measured. Forearm blood flow during reactive hyperaemia and after sublingual nitroglycerin administration was measured by strain-gauge plethysmography. RESULTS: The serum concentrations of total and LDL cholesterol were significantly higher in the E4 group than in the E2 group (P < 0.05) or in the E3 group (P < 0.05). The serum apo B concentration was significantly higher in the E4 group than in the E2 group (P < 0.05). The serum concentrations of high density lipoprotein (HDL) cholesterol and nitrite/nitrate were significantly lower in the E4 group than in the E2 group (P < 0.05). Other lipid concentrations did not differ in the three groups. The serum MDA-LDL concentration was highest in the E4 group, and was lowest in the E2 group (E2: 91.1 +/- 6.9 IU/l, E3: 112.3 +/- 5.9 IU/l, E4: 128.8 +/- 9.9 IU/l; P < 0.05). The forearm blood flow response to reactive hyperaemia was lowest in the E4 group, and highest in the E2 group (E2: 52.2 +/- 5.8 ml/min per 100 ml tissue, E3: 40.7 +/- 1.7 ml/min per 100 ml tissue, E4: 33.4 +/- 2.4 ml/min per 100 ml tissue; P < 0.05). The forearm blood flow changes in response to nitroglycerine were similar between all three groups. CONCLUSIONS: The apo E phenotype affects the serum MDA-LDL concentration and forearm endothelial function in postmenopausal women.

Aged↗

PubMed2003

Photonic molecule lasing.

Lasing at resonantly coupled whispering-gallery mode frequencies is observed in photonic molecules consisting of bispheres of 4.2 and 5.1 microm in diameter placed in a silicon V-groove. We examine spatial profiles of photonic molecule modes by use of frequency-resolved imaging and reveal bonding and antibonding mode features. From the lasing threshold characteristics, we quantitatively measure the quality factor and the spontaneous-emission coupling ratio of the photonic molecule modes and confirm that strong coherent coupling leads to photonic molecule modes.

Journal Article↗