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Biomedical subjects

Shigeru Sakamoto

Publications and source records attributed to Shigeru Sakamoto.

At least 19 recordsLinked to original sources
PubMed2006

Annular reconstruction for mitral valve replacement in a destroyed or calcified mitral annulus.

Mitral valve replacement in the presence of severe annular calcification and an infectious lesion may be complicated by atrioventricular rupture, left circumflex coronary artery injury, and recurrence of infective endocarditis. Confronted with these circumstances, we have developed a technique of annular reconstruction for mitral valve replacement. The prosthetic valve is made by enlarging the circumference of the sewing ring with a Dacron collar. The collar can be sutured to the left atrial wall above the mitral annulus. This technique has been employed in five patients: three had extensive annular calcification, and two had acute valve endocarditis with destruction of mitral annulus. In all cases, the circumferential or partial annular reconstruction permitted secure implantation of the prosthetic valve. The one postoperative death was related to hemodialysis due to chronic renal failure. There were no other fatalities during the postoperative course, and the valves functioned normally. Our results suggest that this technique can be performed in high operative risk patients when mitral valve replacement is impossible using conventional techniques.

Adult↗
PubMed2005

Novel molecular drug carrier: encapsulation of oxaliplatin in cucurbit[7]uril and its effects on stability and reactivity of the drug.

Oxaliplatin forms a stable 1:1 inclusion complex with cucurbit[7]uril as indicated by NMR, mass spectrometry, isothermal titration calorimetry and X-ray crystallography. The encapsulation of the drug results in a large enhancement in stability, a moderate decrease in reactivity toward guanosine but a much larger decrease in reactivity toward L-methionine, which suggests the encapsulation not only increases the stability of the drug but also may reduce unwanted side effects caused by protein binding of the platinum drug. A preliminary in vitro assay using various tumor cell lines reveals that the encapsulation results in a decrease in the antitumor activity of oxaliplatin.

Antineoplastic Agents↗
PubMed2005

Syntheses of hexakis(4-functionalized-phenyl)benzenes and hexakis[4-(4'-functionalized- phenylethynyl)phenyl]benzenes directed to host molecules for guest-inclusion networks.

The syntheses of various types of hexakis(4-functionalized-phenyl)benzenes 1 and hexakis[4-(4'-functionalized-phenylethynyl)phenyl]benzenes 2 by the cobalt-catalyzed cyclotrimerization of diarylacetylenes and by the Sonogashira coupling reaction of 1e with arylacetylenes, respectively, are described. X-ray crystallographic analysis showed that host 1e or 2f forms a 2-D network by unique I...I or CH...O=C interactions, respectively.

Journal Article↗
PubMed2005

Successful surgical treatment of an infrarenal abdominal pseudoaneurysm caused by tuberculosis: report of a case.

A 76-year-old man was admitted to our hospital for investigation of an apparent abdominal aortic aneurysm detected during treatment for epididymitis. A chest X-ray showed miliary shadows in the bilateral lung fields strongly suggestive of tuberculosis. The diameter of the aneurysm increased, and examinations showed impending rupture of a pseudoaneurysm. However, a definitive disease pathogenesis was not obtained before surgery. We performed a subemergency operation, which revealed an infrarenal abdominal pseudoaneurysm caused by tuberculosis. The pseudoaneurysm appeared to have resulted from direct extension of tuberculous lymphadenitis to the aortic wall, which ruptured. We review 24 other cases of tuberculous aortic aneurysms surgically treated in Japan before 2004.

Aged↗
PubMed2005

Intermolecular hydrogen bonding of steroid compounds: PFG NMR diffusion study, cold-spray ionization (CSI)-MS and X-ray analysis.

An extensive analysis of hydrogen bonding of steroid compounds in diluted solution is preformed by pulsed field gradient (PFG) NMR and cold-spray ionization (CSI)-MS, in the solid state by X-ray crystallographic analysis. The formation of hydrogen bond interaction are quantified and discussed. Although X-ray analysis in the crystalline state and CSI-MS measurement in solution suggested that the observed diffusion coefficient D(obs) of the steroid compounds may vary in accordance with the number of hydrogen bonds, the actual observed D(obs) value determined from the diffusion studies diminished constantly without correlation on the decreasing numbers of hydrogen bonds. Comparison of two different calibration profiles of calculated molecular volume (V(cal)) vs. D(obs), which are obtained from compounds possessing no hydrogen bonding and the steroid compounds, formation of a chain structure (cluster) based on intermolecular hydrogen bonding of the steroid compounds is unambiguously confirmed.

Hydrogen Bonding↗
PubMed2005

Hepatitis E virus transmission from wild boar meat.

We investigated a case of hepatitis E acquired after persons ate wild boar meat. Genotype 3 hepatitis E virus (HEV) RNA was detected in both patient serum and wild boar meat. These findings provided direct evidence of zoonotic foodborne transmission of HEV from a wild boar to a human.

Animals↗
PubMed2005

Clinical evaluation of combination therapy for biventricular pacing after cardiac surgery in patients with intractable heart failure.

We examined the effectiveness of combination therapy for biventricular pacing after cardiac surgery. We performed biventricular pacing in seven patients until April 2003. The diagnosis of the patients was ischemic cardiomyopathy (ICM) in four patients and dilated cardiomyopathy (DCM) in three patients. The implantation method of biventricular pacing was performed with a myocardial electrode through a median sternotomy. DDD-R and SSI-R were used to perform biventricular pacing. A Y-adapter was connected to a generator so that the 2 leads could be implanted in both the right ventricles (RV) and left ventricles (LV). The clinical symptoms were New York Heart Association (NYHA) classification of 3.7+/-0.3 preoperatively and 1.8+/-0.6 postoperatively, showing a significant improvement (p<0.001). The cardiac index (CI) was 1.9+/-0.2 L/min/m2 preoperatively and 3.0+/-0.6 L/min/m2 postoperatively (p<0.05). The pulmonary capillary wedge pressure (PCWP) was 19.5+/-2.6 mmHg preoperatively and 13.6+/-2.0 mmHg postoperatively, showing a significant improvement (p<0.05). The intracardiac potential and threshold values were: left atrium 1.9+/-1.0 mV, threshold value (PW: 0.45 msec) 2.1+/-0.6 V, LV 4.9+/-4.23 mV, threshold value (PW: 0.45 msec) 2.2+/-1.51 V, and RV 3.6+/-0.9 V, threshold value (PW: 0.45 msec) 2.0+/-0.7 V. The LV and RV threshold values were high. The QRS interval improved from 158.4+/-18.0 msec preoperatively to 110+/-13.4 msec postoperatively, showing a significant reduction. This combination therapy when compared to the use of the biventricular pacing method used at the current time, does have the risks of cardiac surgery, but the clinical symptoms and hemodynamic performance improvement are great.

Adult↗
PubMed2004

Dynamic equilibrium between a supramolecular capsule and bowl generated by inter- and intramolecular metal clipping.

The metal-induced self-assembly of a resorcin[4]arene derivative 1 that has four pyridine units as pendent groups and two equivalents of [M(dppp)(OTf)(2)] (M=Pd, Pt) results in a dynamic equilibrium between an interclipped supramolecular capsule 3 and an intraclipped bowl 4 in nitromethane, although the interclipped capsule 3 is formed as a sole adduct in chloroform/methanol and the intraclipped bowl 4 is formed exclusively in an aqueous phase. This demonstrates how metal-induced self-assembly can be tuned by subtle changes in the solvent system. The coexistence of the two structures in nitromethane was characterized by NMR spectroscopy and coldspray ionization mass spectrometry (CSI-MS). The crystal structure of the interclipped capsule 3 b, which is composed of two units of ligand 1 and four Pt(II) ions, reveals the capsule cavity to have nanoscale dimensions of 15x20 A. NMR spectra show that the dynamic equilibrium between 3 and 4 is dependent on concentration and temperature. Temperature-dependent (1)H NMR spectroscopy was carried out from 273 to 343 K to verify the thermodynamic parameters that control the dynamic equilibrium process; the conversion from the interclipped supramolecular capsule 3 a to the intraclipped bowl 4 a is entropically favored and enthalpically disfavored. The rotational barrier of the restricted rotation of pyridine units in the intraclipped bowl 4 was determined by line-shape analysis.

Journal Article↗
PubMed2004

Versatile formation of [2]catenane and [2]pseudorotaxane structures; threading and noncovalent stoppering by a self-assembled macrocycle.

A self-assembled dimeric macrocycle between 4,4'-bis(4-pyridylmethoxy)biphenyl (L) and (en)Pd(NO(3))(2) was constructed, and its interactions with cyclodextrins of different cavity size resulted in the formation of [2]catenane and [2]pseudorotaxane systems, respectively. The structures were identified by 1D and 2D NMR spectroscopy and cold spray ionization mass (CSI-MS) spectrometry.

Journal Article↗
PubMed2004

Designed self-assembly of molecular necklaces using host-stabilized charge-transfer interactions.

A novel approach to the noncovalent synthesis of molecular necklaces successfully led to the first quantitative self-assembly of a molecular necklace [6]MN, in which five small rings are threaded on a large ring, from 10 components. Our strategy involves the host-guest complex formation between the molecular host cucurbit[8]uril (CB[8]) and a guest molecule in which an electron donor and an electron acceptor unit are connected by a rigid linker with a proper angle, to form a cyclic oligomer through the host-stabilized intermolecular charge-transfer (CT) complex formation. In the structure of the molecular necklace [6]MN, five molecules of the guest form a cyclic framework by the intermolecular CT interactions, on which five CB[8] molecules are threaded with an arrangement reminiscent of a five-fold propeller. The molecular necklace measures approximately 3.7 nm in diameter and approximately 1.8 nm in thickness.

Journal Article↗
PubMed2004

Reactivity of the human internal thoracic artery to vasodilators in coronary artery bypass grafting.

OBJECTIVE: The internal thoracic artery (ITA) is a useful conduit for coronary artery bypass grafting (CABG) and the patency rate is indispensable. Recently we have developed a method for increasing ITA blood flow during surgery by directly injecting phosphodiesterase III inhibitor (PDE III-I) into the left ITA (LITA) to prevent its contracture. In this study, we compared the reactivity of LITA blood flows before and after injection of four drugs: saline, papaverine hydrochloride, isosorbide dinitrate (ISDN), and PDE III-I. METHOD: 80 patients who were undergoing the first primary CABG, were randomly separated into four groups. Each group consisted of 20 patients. LITA graft free flow (GFF) and systemic mean blood pressure (MBP) were measured before and 1 min after direct intra LITA drug administration and blood vessel resistance (R) was calculated. RESULT: The saline group showed no significant changes in GFF, R value, and MBP. Significant increase in GFF was observed in the PDE III-I and ISDN groups. Except the saline group, each group exhibited a significant decrease in both the R value and MBP. A comparison of the change rate of MBP showed no significant differences among the four groups. The PDE III-I significantly increased the change rate of GFF and decreased the change rate of R value, when compared to the saline and papaverine hydrochloride groups. The PDE III-I showed a tendency to increase the change rate of GFF and to decrease the change rate of the R value compared to the ISDN group. CONCLUSION: The results of this study suggested that the PDE III-I is the most effective for increasing the blood flow of a LITA graft for CABG during surgery.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed2004

Long term outcome of femoropopliteal bypass for claudication and critical ischemia.

We performed 167 femoropopliteal bypass surgeries in 151 patients (95 patients underwent above-knee bypass and 56 below-knee bypass) from December 1985 to December 2000 with the use of prosthetic graft or autologous vein graft. We compared primary patency rates between age, sex, graft material, distal anastomotic site and severity of ischemia, considering their survival rates to elucidate the long-term outcome of above-knee and below-knee femoropopliteal bypass. The 10 year patency rate for above-knee bypass was 47.4%, compared to 36.9% for below-knee ( p < 0.01). Better results were found after bypass surgery for claudicants than for critical ischemia ( p < 0.05). With regard to graft material and age categories, there were unexpectedly no statistical differences in either above-knee or below-knee anastomosis. The survival rate at 10 years in claudicants was 51.2%, compared to 15.9% with critical ischemia ( p < 0.01). Mortality was much influenced by ischemic heart disease ( p < 0.002) and the age of patient ( p < 0.05). The results after above-knee bypass had comparable patency, whereas the results after below-knee bypass were disappointing. Below-knee arterial reconstruction for claudicants should be carefully considered and might be recommended only to patients with critical ischemia.

Age Factors↗
PubMed2004

Reconstruction of bilateral branch pulmonary artery stenosis caused by Takayasu's aortitis.

A 63 year-old female presented with dyspnea on exertion. Her chest X-ray showed cardiomegaly, and right ventricular overload and tricuspid regurgitation were detected. Her pulmonary ventilation and blood flow scintigraphy findings were suspicious of pulmonary vascular disease; the diagnosis was pulmonary hypertension and bilateral branch pulmonary artery stenosis. After the inflammation settled, the stenotic bilateral branch pulmonary artery was reconstructed with a prosthetic vessel and the pulmonary pressure normalized immediately. A resected specimen revealed that the stenotic changes were from Takayasu's disease. The patient's postoperative course was uneventful, and pulmonary ventilation and blood scintigraphy returned to an almost normal range. At follow-up 5 years and 6 months after the operation, there was no evidence of pulmonary artery disease (eg, stenosis and/or ischemia) or of any change in the central vessels of the retina, the so-called Takayasu's retinopathy.

Female↗
PubMed2003

A novel supramolecular multicolor thermometer by self-assembly of a pi-extended zinc porphyrin complex.

A zinc complex of (3-pyridyl)porphyrin with an alkynyl sidearm (1) preferentially formed a cyclic tetramer in toluene, which showed supramolecular thermochromism at ambient temperatures of 0-100 degrees C. Because of an appropriate extension of pi-electronic conjugation of the porphyrin chromophore, the thermal-induced self-assembling dynamics of 1 can be detected as a vivid color change from red to yellow to green. In sharp contrast, 2 without any alkynyl group, on heating, developed only a small color change from orange to pink, while 3 bearing two alkynyl groups stayed green and did not display any thermochromism.

Journal Article↗
PubMed2003

Guest-induced assembly of tetracarboxyl-cavitand and tetra(3-pyridyl)-cavitand into a heterodimeric capsule via hydrogen bonds and CH-halogen and/or CH-pi interaction: control of the orientation of the encapsulated guest.

The guest- or solvent-induced assembly of a tetracarboxyl-cavitand 1 and a tetra(3-pyridyl)-cavitand 2 into a heterodimeric capsule 1.2 in a rim-to-rim fashion via four intermolecular CO(2)H.N hydrogen bonds has been investigated both in solution and in the solid state. In the (1)H NMR study, a 1:1 mixture of1a and 2a (R = (CH(2))(6)CH(3)) in CDCl(3) gave a mixture of various complicated aggregates, whereas this mixture in CDCl(2)CDCl(2) or p-xylene-d(10) exclusively produced the heterodimeric capsule 1a.2a. It was found that an appropriate 1,4-disubstituted-benzene is a suitable guest for inducing the exclusive formation of 1a.2a in CDCl(3). The ability of a guest to induce the formation of guest-encapsulating heterodimeric capsule, guest@(1a.2a), increased in the order p-ethyltoluene < 1-ethyl-4-methoxybenzene < or = 1-ethyl-4-iodobenzene < or = 1,4-dibromobenzene < 1-iodo-4-methoxybenzene < or= 1,4-dimethoxybenzene < or = 1,4-diiodobenzene. The (1)H NMR study revealed that a CH-halogen interaction between the inner protons of the methylene-bridge rims (-O-H(out)CH(in)-O-) of the 1a and 2a units and the halogen atoms of 1,4-dihalobenzenes and a CH-pi interaction between the methoxy protons of 1,4-dimethoxybenzene and the aromatic cavities of the 1a and 2a units play important roles in the formation of 1,4-dihalobenzene@(1a.2a) and 1,4-dimethoxybenzene@(1a.2a), respectively. A preliminary single-crystal X-ray diffraction analysis of guest@(1b.2b) (R = (CH(2))(2)Ph; guest = 1-iodo-4-methoxybenzene or p-xylene) confirmed that the guest encapsulated in 1b.2b is oriented with the long axis of the guest along the long axis of 1b.2b and that the iodo and the methoxy groups of the encapsulated 1-iodo-4-methoxybenzene are specifically oriented with respect to the cavities of the 2b and 1b units, respectively.

Journal Article↗
PubMed2003

A cationic guest in a 24+ cationic host.

A new tetrahedral coordination cage M12L6 was prepared from a linear dipyrimidine ligand (L) and cis-protected palladium(II) (M). This cage showed unprecedented host-guest chemistry where the cationic host accommodated a cationic guest despite 24+ charges on the host framework. The unusual cation-cation host-guest chemistry is described by a unique onionlike shell structure of the host-guest complex where two cationic spheres are mediated by an anionic sphere of a counteranion assembly.

Journal Article↗