Structural and kinetic modification of aqueous hydroxypropylmethylcellulose(HPMC) induced by electron beam irration

Electron beam was irradiated on 10% and 20% hydroxypropylmethylcellulose (HPMC) aqueous solutions with different doses to make gel films. As increasing dose, the gel fraction of the film increased sharply above a critical dose and then decreased gradually after passing a maximum. The scission/cross-linking ratio and the critical dose were determined using the Charlesby-Rosiak equation as 0.52 and 9 kGy for 10% gel and 0.43 and 14 kGy for 20% gel, respectively. The gel fraction for 20% HPMC film was lower at low dose and higher at high dose than that for 10% film. The behavior of the swelling ratio of the gel film was just opposite to that of the gel fraction. The cross-linking density of the gel estimated from the Flory theory linearly increased with irradiation dose at low dose, passed a maximum around 100 and 160 kGy for 10% and 20% films, respectively, and decreased at high dose. These results suggest the competition of scission and cross-linking induced by indirect effect of irradiation. Dielectric relaxation measurement by time domain reflectometry and RF impedance/material analyzer revealed two characteristic relaxations of chain motions around 100MHz and of orientation of free water around 20GHz. From the dose dependence of the relaxation parameters determined by fitting to a combined equation of Cole-Cole type and KWW type, a coupling of motions of HPMC molecules and water molecules was strongly suggested. The critical dose for gelation was coincident with the dose for the maximum of t h and the minimum of Deh together with the minimum of t m and the maximum of Dem, where t h and Deh denote the relaxation time and the relaxation strength for free water molecular motion and t m and Dem the corresponding ones for HPMC molecular motion. The characteristic behavior was discussed in terms of the increase of affinity between HPMC and water and the constrained molecular motion in the gel network

Development of Advanced Biodevices Using Quantum Beam Microfabrication Technology

Biodevices with engineered micro- and nanostructures are strongly needed for advancements in medical technology such as regenerative medicine, drug discovery, diagnostic reagents, and drug delivery to secure high quality of life. The authors produced functional biocompatible plastics and hydrogels with physical and chemical properties and surface microscopic shapes that can be freely controlled in three dimensions during the production process using the superior properties of quantum beams. Nanostructures on a biocompatible poly(L-lactic acid) surface were fabricated using a focused ion beam. Soft hydrogels based on polysaccharides were micro-fabricated using a focused proton beam. Gelatin hydrogels were fabricated using γ-rays and electron beam, and their microstructures and stiffnesses were controlled for biological applications. HeLa cells proliferated three-dimensionally on the radiation-crosslinked gelatin hydrogels and, furthermore, their shapes can be controlled by the micro-fabricated surface of the hydrogel. Long-lasting hydrophilic concave structures were fabricated on the surface of silicone by radiation-induced crosslinking and oxidation. The demonstrated advanced biodevices have potential applications in three-dimensional cell culture, gene expression control, stem cell differentiation induction/suppression, cell aggregation into arbitrary shapes, tissue culture, and individual diagnosis in the medical field

Revascularization of Malignant Coronary Instent Restenosis Resulting From Takayasu's Arteritis Using Sirolimus-Eluting Stents

A 37 year-old female who had suffered from arteritis for 20 years underwent a Bentall operation. Since severe stenosis was observed in her left main coronary artery (LMCA) the following year, a minimally invasive direct coronary artery bypass (MIDCAB) operation was performed. Unfortunately, she again complained of angina about 6 months after the second surgery and coronary angiography (CAG) revealed that her left internal thoracic artery graft was totally occluded. Although a 4.0 × 15 mm S670 stent was placed in her LMCA, the LMCA restenosed every 3 months and she underwent reintervention 8 times. We placed 2 sirolimus-eluting stents for treating the LMCA using the culottes stenting technique. CAG 6 months after the index procedure showed no stenosis at her LMCA. Sirolimus-eluting stents were effective for treating stenosis resulting from arteritis as well as that caused by atherosclerosis

Angiotensin converting enzyme inhibitors attenuated the expression of G-protein coupled receptor kinases in heart failure patients

Background: There are few biological markers, which strictly show the severity of congestive heart failure (CHF). Methods and Results: Lymphocyte G-protein coupled receptor kinase (GRK) mRNA expression was measured by quantitative reverse transcription-polymerase chain reaction in 15 CHF patients: 5 patients classified as New York Heart Association class-II treated with angiotensin converting enzyme inhibitor (ACEI) (IIA), 5 patients in class-II without ACEI (IIC), and 5 patients in class-III treated with ACEI (IIIA). GRK mRNA level in IIIA was significantly higher than those in IIA (p<0.05). GRK mRNA level in IIA were significantly lower than those in IIC (p<0.05). Conclusions: The expression level of lymphocyte GRK might show the severity of CHF, and ACEI treatment could reduce the level of GRK in CHF patients. (Circ J 2006; 70: 362 - 363

Chronic beta-adrenergic receptor stimulation enhances the expression of G-Protein coupled receptor kinases, GRK2 and GRK5, in both the heart and peripheral lymphocytes

Background: Enhanced expression of G protein-coupled receptor kinase (GRK) has been reported in failing hearts and in the present study the stability of enhanced GRK mRNA expression, and the correlation between the expression level of GRK mRNA in peripheral lymphocytes and in the heart were both evaluated. Methods and Results: Isoproterenol was injected into rats for 2 weeks, and then GRK5 mRNA was assessed by quantitative reverse transcriptase-palymerase chain reaction. An enhanced expression of cardiac GRK5 mRNA was observed even after 4 weeks of recovery. The isoproterenol-induced increased expression of GRK2 and GRK5 mRNA was equally observed in the heart and lymphocytes, and there was a close correlation between the heart and lymphocytes in the level of expression of each GRK mRNA. Conclusions: The GRK mRNA level is maintained at a high level for a long period without continuous β-adrenergic receptor stimulation. The level in circulating lymphocytes could be used as a surrogate marker to estimate the level of cardiac GRK expression and, presumably, the β-adrenergic receptor function of cardiomyocytes. (Circ J 2005; 69: 987-990