PubMed Health⌕ Search

Biomedical subjects

Hiroshi Komatsu

Publications and source records attributed to Hiroshi Komatsu.

9 recordsLinked to original sources
PubMed2006

Role of left ventricular regional diastolic abnormalities for global diastolic dysfunction in patients with hypertrophic cardiomyopathy.

BACKGROUND: The usefulness of Doppler strain rate imaging for assessment of left ventricular regional diastolic function has not been fully determined. OBJECTIVE: We aimed to clarify the relationships between diastolic strain rates and global diastolic function and find a useful index for regional diastolic function in patients with hypertrophic cardiomyopathy (HCM). METHODS: Strain rate curves were obtained using an apical approach at 12 different sites of the left ventricular myocardium in 25 patients with HCM and 20 control subjects, and peak early diastolic strain rate (ESR), peak late diastolic strain rate, and the time from QRS to ESR were measured. The flow propagation velocity was measured using color M-mode Doppler echocardiography as a global diastolic index. RESULTS: Each of the spatially averaged values of ESR and ESR/peak late diastolic strain rate and the coefficients of variation of time from QRS to ESR was significantly correlated with flow propagation velocity, but the best correlation was observed in ESR. Although both ESR and peak late diastolic strain rate of each myocardial segment of patients with HCM tended to decrease as the wall thickness increased, only ESR significantly decreased even in the segments without apparent hypertrophy. CONCLUSIONS: In patients with HCM, the reduction of ESR was more closely associated with global diastolic dysfunction than asynchrony, and ESR may be a useful and sensitive index for regional diastolic function.

Cardiomyopathy, Hypertrophic↗
PubMed2006

[Dilation of the brachial artery in response to sublingual nitroglycerin can predict the antihypertensive effects of valsartan: a study using novel high-frequency high-frame-rate ultrasound imaging].

OBJECTIVES: The efficacy of antihypertensive agents can vary in patients. Four to 8 weeks may be required before antihypertensive agents become fully effective. Predicting the efficacy can help agent selection and dose setting. This study determined whether nitroglycerin-induced vasodilation of brachial arteries can predict the antihypertensive action of angiotensin II receptor antagonist. METHODS: Untreated uncomplicated patients with essential hypertension, who gave informed consent, were studied (n = 20, mean age 55 years). Before antihypertensive treatment, nitroglycerin-induced vasodilation of the brachial arteries was measured using a novel method of 15 MHz high-frequency high-frame-rate ultrasound imaging (Hitachi EUB8000). Diameter of the brachial artery at the end-systolic phase was measured before and after 0.3 mg nitroglycerin sublingual spray and percentage vasodilation (%D-N) was calculated. The reduction of mean blood pressure after nitroglycerin (%BP-N) was calculated. Valsartan monotherapy (40-80 mg/day)was administered for 3-6 months (mean 132 days). Reduction of mean blood pressure after valsartan monotherapy (%BP-V) was calculated. RESULTS: Valsartan decreased systolic blood pressure from 138 +/- 13 to 130 +/- 17 mmHg, and diastolic blood pressure from 83 +/- 11 to 78 +/- 11 mmHg (p < 0.05). %D-N was correlated closely with %BP-V (r = - 0.70, p < 0.001). %BP-N had no correlation with %BP-V (r = 0.13, p = 0.58). CONCLUSIONS: Direct vasodilatory action of nitroglycerin on vascular smooth muscle cells may predict the chronic antihypertensive effect of angiotensin II receptor antagonist.

Angiotensin II Type 1 Receptor Blockers↗
PubMed2004

Scientific approach to the optimization of protein crystallization conditions for microgravity experiments.

The National Space Development Agency of Japan (NASDA) developed a practical protocol to optimize protein crystallization conditions for microgravity experiments. This protocol focuses on the vapor diffusion method using high density protein crystal growth (HDPCG)--hardware developed by the University of Alabama, Birmingham--that flew on the STS-107 mission. The objective of this development was to increase the success rate of microgravity experiments by setting crystallization conditions based on knowledge of crystal growth and fluid dynamics. The protocol consists of four steps: (1) phase diagram preparation, (2) estimation of condensation rate in the vapor diffusion method, (3) fluid dynamic property measurement, and (4) fluid dynamic simulation. First, a phase diagram was constructed. Crystallization characteristics were investigated by a microbatch method. The data were recalculated based on classical nucleation theory and the crystallization boundary was determined as a function of time. The second step was to develop a practical model to estimate the condensation rate of the crystallizing solution, including protein and precipitant, as a function of the precipitant concentration and solution volume. By considering the crystallization map and the vapor diffusion condensation model we were able to optimize the crystallization conditions that generate crystals in the desired time. This was particularly important in a shuttle mission whose mission duration is limited. The third step was fluid dynamic property measurement necessary for fluid dynamics simulation and crystal growth study. The last step was to estimate the mass transport in space on the basis of the fluid dynamics simulation transport model. It turned out that neither the vapor phase nor the solution phase was seriously affected by gravity until nucleation provided the hardware was set in a normal direction. Therefore, we concluded that the optimized crystallization conditions could be directly applied to microgravity experiments. By completing the approach, we were able to control the time for nucleation in the vapor diffusion method.

Animals↗
PubMed2004

A woman with infectious endocarditis caused by Abiotrophia defectiva.

A 74-year-old woman with recurrent fever and multiple joint pain was admitted to Hokkaido University Hospital. Trans-esophageal echocardiogram revealed bacterial vegetation and destruction of the aortic valve. Although few bacteria grew in regular blood agar, Gram-positive coccobacillus was specifically grown in chocolate blood agar and Brucella agar, and it was identified to be Abiotrophia defectiva. Infectious endocarditis caused by Abiotrophia defectiva was diagnosed, she was treated with diuretics, penicillin G and gentamicin, and she immediately improved. Infectious diseases caused by Abiotrophia defectiva are extremely rare, and identification of this pathogen is important, as its bacterial characteristics require proper attention.

Aged↗
PubMed2003

Impurity effects on lysozyme crystal growth.

Atomic force microscopy (AFM) and X-ray diffraction experiments have been combined to study the correlation between impurity incorporation, crystal surface morphology and crystal quality. Hen egg-white lysozyme has been used as a model protein, and covalently bound lysozyme dimer as a model impurity. AFM observation of the [101] crystal face revealed that the crystal surface clearly became rough when 5% impurity was added, and the steps disappeared as the impurity concentration increased to 10%. The crystal quality was evaluated by four factors: maximum resolution limit, / , Rmerge, and overall B factor. In every index, the crystal quality tended to degrade as the impurity concentration increased. The B-factor dropped significantly at 5% impurity; at the same time the step roughening was observed. This strongly suggested that the impurity incorporation affected the step growth mechanism and degraded the crystal quality.

Crystallization↗
PubMed2003

Improvement of protein crystal quality by forced flow solution.

Flow experiments in growing protein crystals were conducted to clarify the influence of the solution flow on the crystal quality. Lysozyme crystals grown under various flow velocities were analyzed by using synchrotron radiation to assess the quality. As a result, the crystals grown under forced flow were of better quality than those grown in quiescent conditions.

Crystallization↗
PubMed2002

Protein crystallization under high pressure.

Pressure is expected to be an important parameter to control protein crystallization, since hydrostatic pressure affects the whole system uniformly and can be changed very rapidly. So far, a lot of studies on protein crystallization have been done. Solubility of protein depends on pressure. For instance, the solubility of tetragonal lysozyme crystal increased with increasing pressure, while that of orthorhombic crystal decreased. The solubility of subtilisin increased with increasing pressure. Crystal growth rates of protein also depend on pressure. The growth rate of glucose isomerase was significantly enhanced with increasing pressure. The growth rate of tetragonal lysozyme crystal and subtilisin decreased with increasing pressure. To study the effects of pressure on the crystallization more precisely and systematically, hen egg white lysozyme is the most suitable protein at this stage, since a lot of data can be used. We focused on growth kinetics under high pressure, since extensive studies on growth kinetics have already been done at atmospheric pressure, and almost all of them have explained the growth mechanisms well. The growth rates of tetragonal lysozyme decreased with pressure under the same supersaturation. This means that the surface growth kinetics significantly depends on pressure. By analyzing the dependence of supersaturation on growth rate, it was found that the increase in average ledge surface energy of the two-dimensional nuclei with pressure explained the decrease in growth rate. At this stage, it is not clear whether the increase in surface energy with increasing pressure is the main reason or not. Fundamental studies on protein crystallization under high pressure will be useful for high pressure crystallography and high pressure protein science.

Animals↗