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Biomedical subjects

Koji Tsuchiya

Publications and source records attributed to Koji Tsuchiya.

18 recordsLinked to original sources
PubMed2007

Cationic surfactant changes the morphology of DNA molecules.

The effect of cetyltrimethylammonium bromide (CTAB), a cationic surfactant, was investigated on the aggregated form of DNA molecules in water at a given temperature. CTAB caused changes in the aggregated form of DNA molecules from loosely packed spherical to rodlike through toroidal one with increasing concentration below the critical micelle concentration (CMC). The change was suggested to arise from the ion complex formation between CTAB and DNA molecules due to the electrostatic interaction, thereby reducing the surface charge and solubility in water of the latter.

Cations↗
PubMed2006

Adsorption and aggregation properties of heterogemini surfactants containing a quaternary ammonium salt and a sugar moiety.

A novel heterogemini surfactant comprising two hydrocarbon chains and two different hydrophilic groups such as a quaternary ammonium cation and gluconamide nonion N,N-dimethyl-N-[2-(N'-alkyl-N'-gluconamide)ethyl]-1-alkylammonium bromides (2CnAmGlu, where n represents hydrocarbon chain lengths of 8, 10, 12, and 14) was synthesized by reacting N,N-dimethylethylenediamine with alkyl bromide, followed by a reaction with 1,5-D(+)-gluconolactone. The adsorption properties of 2CnAmGlu were characterized by surface tension measurements made using the Wilhelmy plate method, and their aggregation properties were investigated by dynamic light scattering and cryogenic transmission electron microscopy techniques. The relationship between the hydrocarbon chain length and the logarithm of the critical micelle concentration (cmc) for 2CnAmGlu exhibited a linear decrease when the chain length was increased up to 12 and then a departure from linearity at n=14. The surface tension reached 24-26 mN m-1 at each cmc, indicating high efficiency in lowering the surface tension of water. Furthermore, it was found that the structure of the aggregate formed for 2CnAmGlu in solution was influenced by the hydrocarbon chain length; that is, for n=10 and 12, micelles with a hydrodynamic radius of 2-5 nm were formed, whereas vesicles were also observed for n=14.

Adsorption↗
PubMed2006

Polymerizable cationic gemini surfactant.

A polymerizable cationic gemini surfactant, [CH(2)=C(CH(3))COO(CH(2))(11)N(+)CH(3))(2)CH(2)](2).2Br(-), 1 has been synthesized and its basic interfacial properties were investigated (in water and in the presence of 0.05 M NaBr). For comparison, the properties of monomeric surfactant corresponding to 1, CH(2)=C(CH(3))COO(CH(2))(11)N(+)(CH(3))(3).Br(-), 2, were also investigated. Parameters studied include cmc (critical micelle concentration), C(20) (required to reduce the surface tension of the solvent by 20 mN/m), gamma(cmc) (the surface tension at the cmc), Gamma(cmc) (the maximum surface excess concentration at the air/water interface), A(min) (the minimum area per surfactant molecule at the air/water interface), and cmc/C(20) ratio (a measure of the tendency to form micelles relative to adsorb at the air/water interface). For the polymerizable gemini surfactant, 1, the methacryloxy groups at the terminal of each hydrophobic group in a molecule have no contact with the air/water interface in the monolayer, whereas for the corresponding monomeric surfactant, 2, the methacryloxy group contacts at the interface forming a looped configuration like a bolaamphiphile. Polymerized micelles of the gemini surfactant are fairly small monodisperse and spherical particles with a mean diameter of 3 nm.

Journal Article↗
PubMed2006

Aortic operation after previous coronary artery bypass grafting: management of patent grafts for myocardial protection.

OBJECTIVES: Aortic surgery for progressive aortic valve disease or aortic aneurysm after previous coronary artery bypass grafting (CABG) is a challenging procedure. We report the outcome of aortic reoperation after previous CABG and evaluate our management of patent grafts and our methods for obtaining myocardial protection. METHODS: From February 2001 to July 2003, 6 patients with progressive aortic valve disease and aneurysm of the thoracic aorta were operated on. The group comprised 3 men and 3 women with a mean age of 67.6 years. There were 4 patients with an aneurysm of the aortic arch, 1 with chronic ascending aortic dissection, and 1 with progressive aortic valve stenosis. The interval between previous CABG and aortic surgery was 74.0 +/- 44.2 months. All reoperations were performed via median resternotomy. Myocardial protection was obtained by hypothermic perfusion of patent in-situ arterial grafts following cold-blood cardioplegia administration via the aortic root under aortic cross clamping. RESULTS: The operative procedure was aortic arch replacement in 4 patients, ascending aortic replacement with double CABG in 1, and aortic valve replacement in 1. All patients survived the reoperation. Postoperative maximum creatine kinase-MB was 49.2 +/- 29.8 and no new Q-waves occurred in the electrocardiogram nor were any new wall motion abnormalities recognized on echocardiography. There were no late deaths during a follow-up of 30.7 months. CONCLUSION: Reoperative aortic procedures after CABG can be performed safely with myocardial protection via hypothermic perfusion of a patent in-situ arterial graft.

Aged↗
PubMed2006

An alpha-L-arabinofuranosidase/beta-D-xylosidase from immature seeds of radish (Raphanus sativus L.).

The carbohydrate moieties of arabinogalactan proteins (AGPs) are essential for their physiological functions and undergo rapid turnover in vivo. Degradation of the carbohydrate moieties of AGPs seems to occur by concerted action of several glycosidases, among them alpha-L-arabinofuranosidase, beta-D-galactosidase, and beta-D-glucuronidase. Here, a bifunctional alpha-L-arabinofuranosidase/beta-D-xylosidase from immature seeds of radish (Raphanus sativus L.), which hydrolyses alpha-L-arabinofuranosyl residues of the carbohydrate moieties of AGPs, has been cloned by reverse transcriptase-PCR. The gene, designated RsAraf1, contained an open reading frame of 2343 bp (780 amino acids), including a putative signal sequence (33 amino acids) at the N-terminus. RsAraf1 is highly similar to barley alpha-L-arabinofuranosidase/beta-D-xylosidases and belongs to family 3 of the glycosyl hydrolases based on sequence homology. Southern blot analysis revealed that several related genes exist in the radish genome. RsAraf1 is expressed throughout seed development and weakly expressed in young seedlings. It was found that alpha-L-arabinofuranosidase activity in a cell-wall protein fraction prepared from transgenic Arabidopsis plants with enhanced expression of RsAraf1 was significantly higher than that in a wild-type protein fraction; the crude enzyme preparation released L-arabinose from radish AGPs as well as alpha-(1-->5)-arabinan and arabinoxylan. Accordingly, the amount of L-arabinosyl residues in the cell walls of transgenic plants was significantly decreased. These results indicate that RsAraf1 encodes a bifunctional alpha-L-arabinofuranosidase/beta-D-xylosidase and suggest that RsAraf1 is involved in the hydrolysis of the carbohydrate moieties of AGPs in immature radish seeds.

Amino Acid Sequence↗
PubMed2006

Calorimetry and cryo-transmission electron microscopic studies of PEG2000-grafted liposomes.

The phase behavior of poly(ethylene glycol) grafted liposomes (PEG-liposomes) was investigated by differential scanning calorimetry (DSC), dynamic light scattering (DLS) and cryo-transmission electron microscopy (cryo-TEM). PEG-liposomes were prepared from mixtures of dipalmitoyl phosphatidylcholine (DPPC) and distearoyl phosphatidylethanolamine with a covalently attached PEG molecular weight of 2000 (DSPE-PEG2000). From the results of DLS measurements, the coexistence of PEG-liposomes and small molecular assemblies were confirmed at mole fractions of DSPE-PEG2000 above about 0.1. Moreover, it was confirmed that small molecular assemblies were disk micelles by cryo-TEM. However, the phase transition enthalpies of PEG-liposomes were hardly changed according to the DSC measurement, though the mole fraction of the PEG lipid increased. From these results, it was suggested that the phase transition enthalpies hardly changed despite mixed micelles being formed because the bilayer structure of the disk micelle maintains high cooperativity between the DPPC molecules.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed2006

Abdominal aortic grafting for renal and lower extremity hypoperfusion due to aortic dissection with progressive thrombosis of a false channel.

We present the case of a 53-year-old man with renal and bilateral limb ischemia due to Stanford B aortic dissection. The thrombosis of the false lumen had progressed and compressed the true lumen, developing renal and leg ischemia. Urgent graft replacement of the infrarenal abdominal aorta with proximal fenestration was successfully performed and the patient was discharged without complications.

Aortic Dissection↗
PubMed2006

[Prophylactic effect of magnesium infusion against postoperative atrial fibrillation].

BACKGROUND: Atrial fibrillation (AF) is a common complication of cardiac operation. For the development of postoperative AF, various risk factors have been identified over the years. In a recent study, it was detected that low serum magnesium levels was an independent predictor of AF after coronary artery bypass grafting (CABG). The purpose of this study was to assess the prophylactic effect of intravenous magnesium infusion on postoperative AF. METHODS: A total of 62 consecutive patients who had elective, first time cardiac operation on cardiopulmonary bypass were prospectively categorized to 2 group. In the treatment group, 30 patients received 8.3 mmol of magnesium sulfate in 100 ml of saline solution that was administered over 4 hours, preoperatively, just after admission in the ICU, and at the postoperative day 1, 2, 3, and 4. RESULTS: Postoperative AF occurred in 3/30 (10.0%) patients in the treatment group and in 14/32 (43.8%) patients in the control group (p<0.01). The arrhythmia developed on the 2.9 postoperative day on average. The postoperative length of hospital stay was significantly shortened in the treatment group (15.9 +/- 4.0 days) than that in the control group (20.5 +/- 7.0, p < 0.01). CONCLUSION: Our findings indicate that magnesium sulfate infusion is effective for the prophylaxis of post operative AF.

Atrial Fibrillation↗
PubMed2005

Effective form of sulfoquinovosyldiacyglycerol (SQDG) vesicles for DNA polymerase inhibition.

Sulfoquinovosyldiacyglycerol (SQDG) has a wide range of biological activities that make it an attractive compound for the development of new drugs. Chemically synthesized beta-SQDG-C(18:0) (1,2-di-O-stearoyl-3-O-(6-deoxy-6-sulfo-beta-d-glucopyranosyl)-sn-glycerol), for example, has a potent inhibitory effect on DNA polymerases. We investigated the properties of the vesicle form of beta-SQDG-C(18:0) as the monomer has low solubility in water. The structure of the beta-SQDG-C(18:0) vesicles are highly influenced by NaCl concentration in preparation process. At low NaCl concentrations, the beta-SQDG-C(18:0) vesicles have high surface curvature and form small unilamellar vesicles. Increases in NaCl concentration, resulted in decreased surface curvature and a tendency for beta-SQDG-C(18:0) to form large multilamellar vesicles. The small unilamellar vesicles showed a potent inhibitory effect on DNA polymerase beta, whereas the large multilamellar vesicles had no such effect. We investigated further the relationship between vesicle size and activity by preparing smaller vesicles (262, 99 and 43 nm in diameter) using an extrusion technique. These smaller vesicles had a greater inhibitory effect on DNA polymerase beta activity than non-extruded vesicles. beta-SQDG-C(18:0) vesicles, especially those of small size, were effective in DNA polymerase inhibition and are expected to have high applicability in DNA polymerase study.

Calorimetry, Differential Scanning↗
PubMed2005

Photoinduced reversible change of fluid viscosity.

We report a reversible photoinduced fluid viscosity change. A small amount of a "photoswitchable" azobenzene-modified cationic surfactant (4-butylazobenzene-4'-(oxyethyl)trimethylammonium bromide, AZTMA) was added to a wormlike micellar solution of cetyltrimethylammonium bromide (CTAB) containing sodium salicylate (NaSal). The trans-AZTMA solution had a remarkably high viscosity as a result of the entangled network of wormlike micelles. UV light irradiation on the trans-AZTMA solution remarkably decreased the viscosity of the solution because the bulky structure of cis-AZTMA is likely to disrupt the network structure of wormlike micelles. This photoinduced viscosity change is perfectly reversible between the trans- and cis-AZTMA solutions.

Journal Article↗
PubMed2005

Leaflet folding plasty for mitral valve repair: technical application and early outcome.

OBJECTIVES: Leaflet folding plasty was introduced for avoiding systolic anterior motion and coronary artery injury after mitral valve repair. We report the application and early outcome of this technique for mitral valve regurgitation. METHODS: From January 1997 to January 2004, 16 patients with mitral valve regurgitation were operated on using leaflet folding plasty. The group comprised 9 men and 7 women, with a mean age of 61.6 years. There were 15 patients with degenerative and 1 with ischemic mitral valve disease. The causes of mitral regurgitation were posterior mitral leaflet prolapse in 11 patients and commissural prolapse in 5 patients. RESULTS: Mitral valve reconstruction could be performed in all patients. There were no perioperative deaths. Postoperative mitral regurgitation fell to 0.13+/-0.52 compared with 3.6+/-0.51 preoperatively. Systolic anterior leaflet motion was not observed in any patients after the procedure. The mean follow-up period was 22 months. There were no late deaths and reoperation was not required during follow-up. CONCLUSIONS: Early outcome of leaflet folding plasty for mitral valve repair was satisfactory. This technique may have advantages to accomplish mitral valve repair safely in patients with mitral regurgitation due to posterior or commissural prolapse.

Adult↗
PubMed2004

Control of viscoelasticity using redox reaction.

The viscoelasticity of a fluid was tuned with the Faradaic reaction of (11-ferrocenylundecyl)trimethylammonium bromide (FTMA), a "redox-switchable" surfactant. An aqueous solution of the reduced form of FTMA exhibited a remarkable viscoelasticity in the presence of sodium salicylate (NaSal) because of the formation of three-dimensional entanglement of wormlike micelles. Electrolytic oxidation of FTMA caused the viscosity of the system to dramatically decrease and the elasticity to disappear. This drastic decrease in viscoelasticity arose from the disruption of wormlike micelles. This novel electrorheological phenomenon is expected to be applicable to ink for inkjet printers, the electrochemically controlled release of substances entrapped in wormlike micelles of FTMA, and fluid flow rate control using electric signals.

Journal Article↗
PubMed2004

Temperature-dependent vesicle formation of aqueous solutions of mixed cationic and anionic surfactants.

The phase behavior of aqueous solutions of mixed cetyltrimethylammonium bromide (CTAB) and sodium octyl sulfate (SOS) was examined at different temperatures (20, 30, 40, and 50 degrees C). While stable vesicles were formed in a narrow composition range on the SOS-rich side at 20 degrees C, the range widened remarkably when the temperature was raised to 30 degrees C. Thus, the vesicle region extended to cover almost the entire composition range, CTAB:SOS = 0.5:9.5-5.0:5.0, at the total surfactant concentrations of 50-70 mM on the SOS-rich side. To analyze the temperature dependence of this phase behavior of the mixed surfactant system, DSC and fluorescence polarization measurements were performed on the system. The experimental findings obtained revealed that pseudo-double-tailed CTAB/SOS complex, the major component of the bimolecular membrane formed by the surfactant mixture, undergoes a gel (Lbeta)-liquid crystal (Lalpha) phase transition at about 26 degrees C. This phenomenon was interpreted as showing that the bimolecular membrane has no curvature and is rigid and easy to precipitate at temperatures below the phase transition point, whereas it has a curvature and is loose enough to disperse in the solution as vesicles at temperatures above the phase transition point. Vesicles formed by the anionic/cationic surfactant complex were then stable at temperatures above the phase transition temperature of the complex.

Journal Article↗
PubMed2004

Successful CABG in a patient with paroxysmal nocturnal hemoglobinuria.

Paroxysmal nocturnal hemoglobinuria (PNH) is an uncommon acquired disorder of blood cells characterized by intravascular hemolysis due to an inordinate sensitivity to complement-mediated membrane damage. This report documents coronary artery revascularization in a patient with PNH, which has not been described in the literature so far. We used the on-pump procedure in the present patient and successfully performed revascularization by taking prophylactic measures against hemolysis.

Adrenal Cortex Hormones↗
PubMed2003

Unexpected durability of Smeloff-Cutter aortic ball valve prosthesis.

We report a case in which replacement of a Smeloff-Cutter aortic ball prosthesis was required 28 years after initial implantation. A 57-year-old woman underwent aortic valve replacement with a 21-mm Smeloff-Cutter ball prosthesis and open mitral commissurotomy for aortic stenosis, aortic regurgitation, and mitral stenosis in 1973. Severe aortic regurgitation occurred in April 2001, and aortic valve reoperation combined with mitral valve replacement was successfully performed. The patient's aortic ball valve was nearly intact with perivalvular leakage probably causing the aortic regurgitation. Our experience documents longer durability for the Smeloff-Cutter prosthesis than has been reported to date.

Aortic Valve↗
PubMed2002

Leukotriene D4 upregulates eosinophil adhesion via the cysteinyl leukotriene 1 receptor.

BACKGROUND: Eosinophils (EOS) are one of the cellular sources of cysteinyl leukotrienes (cysLTs) in allergic inflammation. There is evidence that cysLT(1)receptor antagonists possess anti-inflammatory properties in vivo in asthmatic airways. Although the exact mechanism of action remains unknown, cysLTs might regulate the cellular responses involved in allergic inflammation. OBJECTIVE: The present study was undertaken to examine whether LTD(4)modifies the adhesive property of EOS. METHODS: EOS were isolated from the blood of healthy subjects. Their adhesion to tissue culture plates or recombinant human (rh) adhesion proteins was then examined in the presence or absence of LTD(4). RESULTS: LTD(4)significantly augmented EOS adhesion to tissue culture plates (adhesion: 5.0% +/- 0.5% by medium control vs 9.1% +/- 1.2% by 1 micromol/L; P <.01; n = 10). The enhanced adhesion induced by LTD(4) was blocked by pranlukast, a cysLT(1) receptor antagonist, or an anti-beta(2) integrin antibody. Flow cytometry analysis revealed that LTD(4) significantly enhanced the expression of CD11b and CD18 on the EOS surface. Finally, LTD(4) augmented EOS adhesion to rh intercellular cell adhesion molecule 1 but not to rh vascular cell adhesion molecule 1 or fibronectin. CONCLUSIONS: The results suggest that LTD(4) directly upregulates the adhesive property of EOS via the cysLT(1) receptor and beta(2) integrin. LTD(4) generated from EOS or cells of some other type might contribute to the development of phenotypic change in airway EOS.

Adult↗
PubMedDate not supplied

Delayed presentation of injury to the sinus of valsalva with aortic regurgitation resulting from penetrating cardiac wounds.

A 39-year-old man had attempted to commit suicide using a small knife to penetrate the anterior chest wall. An emergency operation was performed successfully to repair the penetrating cardiac injury of the right ventricular outflow tract without using cardiopulmonary bypass. Two years after the operation, he was complained of dyspnea and a continuous murmur was detected. Echocardiography and cardiac catheterization revealed aorto-right ventricular fistula in the sinus of valsalva with aortic regurgitation. In operation, the healed laceration of the right coronary cusp and the fistula between aorta and right ventricle were identified. The fistula was closed using a Dacron patch and the aortic valve was replaced with a mechanical valve. Long-term follow-up of penetrating thoracic injuries is important for detecting underlying intracardiac lesions.

Adult↗