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Yokohama-shi, Japan

Koizumi H.,Tohoku University | Uda S.,Tohoku University | Fujiwara K.,Tohoku University | Tachibana M.,Yokohama City University | And 2 more authors.
Journal of Applied Crystallography | Year: 2013

X-ray diffraction rocking-curve measurements were performed on tetragonal hen egg white lysozyme (HEWL) crystals grown with and without application of an external alternating current (AC) electric field, and then the crystal quality was assessed by the FWHMs of each rocking-curve profile. The FWHMs for HEWL crystals grown with an external electric field were smaller than those for crystals grown without. In particular, the average FWHM for the 12 12 0 reflection with an external electric field (0.0034°) was significantly smaller than that without (0.0061°). This indicates that the crystal quality of HEWL crystals was improved by application of the external AC electric field. This crystallization technique can be expected to enhance the resolution of protein molecule structure analysis by X-ray diffraction. © 2013 International Union of Crystallography.

Koizumi H.,Tohoku University | Tachibana M.,Yokohama City University | Yoshizaki I.,Japan Aerospace Exploration Agency | Fukuyama S.,Advanced Engineering Services Co. | And 4 more authors.
Crystal Growth and Design | Year: 2014

Glucose isomerase crystals with thicknesses of 0.5 mm were grown using seed crystals. The thickness required for better X-ray topographic images by kinematical theory is determined by the extinction distance, g. The seed crystals were cross-linked with glutaraldehyde to maintain stability for a long period before the growth experiments. Dislocations that were produced during the growth of such thick glucose isomerase crystals were observed as clearly as those in inorganic crystals via X-ray topography with monochromatic-beam synchrotron radiation, which is attributed to the high quality of the glucose isomerase crystals. This also indicates that high-quality protein crystals can be grown using seed crystals. The dislocations extended from the interface with the cross-linked seed crystal to the surface of the grown crystal; however, no dislocations were generated if the seed crystal was not cross-linked. We discuss the effect of the chemical cross-linking of the seed on the generation of dislocations from seed crystals. © 2014 American Chemical Society.

Koizumi H.,Tohoku University | Uda S.,Tohoku University | Fujiwara K.,Tohoku University | Tachibana M.,Yokohama City University | And 2 more authors.
Journal of Applied Crystallography | Year: 2015

The effect of a 20kHz external electric field on the quality of tetragonal hen egg white (HEW) lysozyme crystals was investigated using X-ray diffraction rocking-curve measurements. The full width at half-maximum was found to be larger for high-order reflections but smaller for low-order reflections. In particular, it was revealed that a large amount of local strain is accumulated in tetragonal HEW lysozyme crystals grown under an applied field at 20kHz. Comparison with previous results obtained for crystals grown with an applied field at 1MHz [Koizumi, Uda, Fujiwara, Tachibana, Kojima & Nozawa (2013). J. Appl. Cryst. 46, 25-29] indicated that improvement of the protein crystal quality could be achieved by selection of an appropriate frequency for the applied electric field, which has a significant effect on the growth of the solid. © 2015 International Union of Crystallography.

Nishimura M.,National Hospital Organization Chiba East National Hospital | Kato Y.,National Hospital Organization Nagoya Medical Center | Tanaka T.,National Hospital Organization Mie Chuo Medical Center | Todo R.,National Hospital Organization Osaka Medical Center | And 6 more authors.
Hypertension Research | Year: 2013

The Home Blood Pressure for Diabetic Nephropathy (HBP-DN) study is a prospective cohort study to determine the optimal home blood pressure (HBP) required to improve the prognosis of type 2 diabetic patients with microalbuminuria. The glomerular filtration rate (GFR) is heterogeneous in microalbuminuric diabetic patients. The first step of the HBP-DN study explored the significance of estimating GFR for the identification of patients for whom HBP measurement would be more helpful. The patients were divided into two groups based on their estimated GFR (eGFR): a low eGFR group (eGFR <60 ml min -1 per 1.73 m2, N=75) and a preserved eGFR group (eGFR ≥60 ml min-1 per 1.73 m2, N=193). HBP, variability of HBP and a previous history of vascular complications were compared between the two groups. The number of antihypertensive drugs used for the patients and the s.d. of home systolic blood pressure (HSBP) in the low eGFR group were significantly higher than those in the preserved eGFR group. A stepwise multiple linear regression analysis also revealed that the low eGFR group was independently correlated with the s.d. of HSBP. A multiple logistic regression analysis revealed that a low eGFR was an independent risk factor for coronary heart disease and advanced retinopathy. Estimating the GFR is important to identify patients with elevated blood pressure variability, as well as those with a high risk of vascular complications. Measuring HBP would be more helpful for the effective and safe treatment of hypertension in patients with a low eGFR than in those with a preserved eGFR. © 2013 The Japanese Society of Hypertension. All rights reserved.

Kitajima N.,CITIZEN HOLDINGS CO. | Tsukashima S.,Yokohama City University | Fujii D.,Yokohama City University | Tachibana M.,Yokohama City University | And 3 more authors.
Physical Review E - Statistical, Nonlinear, and Soft Matter Physics | Year: 2014

The ultrasonic sound velocities of cross-linked orthorhombic hen egg-white lysozyme (HEWL) crystals, including a large amount of water in the crystal, were measured using an ultrasonic pulse-echo method. As a result, seven elastic constants of orthorhombic crystals were observed to be C11 = 5.24 GPa, C22 = 4.87 GPa, C12 = 4.02 GPa, C33 = 5.23 GPa, C44 = 0.30 GPa, C55 = 0.40 GPa, and C66 = 0.43 GPa, respectively. However, C13 and C23 could not be observed because the suitable crystal planes could not be cut from bulk crystals. We conclude that the observed elastic constants of the cross-linked crystals are coincident with those of the intrinsic crystals without cross-linking. Moreover, the characteristics of the elastic constants in orthorhombic HEWL crystals are due to the fact that the shear elastic constants, C44, C55, and C66, are softer than in tetragonal crystals. That is, the shear components, C44, C55, and C66, are one half of those of the tetragonal crystals. © 2014 American Physical Society.

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