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Biomedical subjects

Hiroyuki Nishi

Publications and source records attributed to Hiroyuki Nishi.

15 recordsLinked to original sources
PubMed2006

Right coronary artery spasms triggered by mechanical compression during off-pump coronary artery bypass grafting surgery.

In this case report, we describe recurrent spasms of the right coronary artery with no apparent preexisting abnormal angiogram that caused second-degree atrioventricular (AV) block and inferior wall hypokinesis. These hemodynamic changes were induced by mechanical compression of the right coronary artery by a pericardium drain tube. From our experience, we should be aware that mechanical compression may trigger an exaggerated vasomotor response, leading to severe coronary artery spasms.

Aged↗
PubMed2006

Structural scaffold of 18-crown-6 tetracarboxylic Acid for optical resolution of chiral amino acid: x-ray crystal analyses of complexes of D- and L-isomers of serine and glutamic acid.

(+)-18-crown-6 tetracarboxylic acid (18C6H4) has been used as a chiral selector for D/L-amino acids in HPLC, where L-isomer is usually eluted prior to D-isomer, except for the case of serine. To clarify why serine exhibits the reverse order for the elusion, the chiral interactions of D- and L-serines with (+)-18C6H4 were investigated by the X-ray single crystal analyses, together with the case of D- and L-glutamic acids, which exhibit the usual elution order in HPLC. The backbone structures (amino, Calpha-H and carboxyl groups) of these four amino acids showed the nearly same interaction with (+)-18C6H4 despite their different chirality. In contrast, the hydroxyl group of L-serine side chain formed a hydrogen bond with the carboxyl group of (+)-18C6H4, whereas such a interaction was not formed for the side chain of D-serine and D- and L-glutamic acids. Thus, it was shown that the exception of D/L-serine from the first elution rule of L-isomer in HPLC is due to the presence and absence of a hydrogen bond formation of its side chain OH group.

Amino Acids↗
PubMed2005

Enantiomeric purity determination of acetyl-L-carnitine by NMR with chiral lanthanide shift reagents.

Enantiomer signal separation of acetyl-carnitine chloride was obtained on a 500 MHz Nuclear Magnetic Resonance (1H NMR) analysis by fast diastereomeric interaction with chiral shift reagents such as chiral lanthanide-camphorato or chiral samarium-pdta shift reagents. Effects of the kinds of chiral shift reagents and the molar ratio of chiral shift reagent to acetyl-carnitine chloride on enantiomer signal separation were investigated and evaluated. Optimization of the experimental conditions provided two significant split signals for the enantiomers, leading to the successful quantitative analysis. Distinguishment of 0.5% of the minor enantiomer (D-form) in acetyl-L-carnitine chloride was found to be possible by 1H NMR with tris[3-(heptafluoropropylhydroxymethylene)-D-camphorato] and praseodymium derivative, (Pr[hfc]3), as chiral shift reagents.

Acetylcarnitine↗
PubMed2005

Optimal method of coronary endarterectomy for diffusely diseased coronary arteries.

BACKGROUND: Although several techniques for coronary artery bypass grafting have been introduced that incorporate coronary endarterectomy (CE), there is little information about late patency among the various CE methods. To clarify the quality of CE, we assessed clinical and angiographic results of our experience with this procedure on 127 patients who had diffusely diseased coronary arteries. METHODS: Between January 1994 and December 2002, 127 patients underwent coronary artery bypass grafting with CE. Sixty-eight patients undergoing CE with long arteriotomies and on-lay patch bypass grafting (group O) were compared with 59 patients undergoing CE with the conventional pull-out method (group P). RESULTS: Thirty-day mortality was 2.9% in group O and 6.8% in group P. The early angiographic results of 115 patients revealed a patency rate of 92.1% (grade A: 79.4%) in group O and 88.6% (grade A: 68.6%) in group P. Actuarial survival at 5 years was 90.7% in group O and 74.0% in group P (p = 0.1). Angiograms performed on 78 patients after a mean period of 21 +/- 16 months showed a patency rate of 89.1% (grade A:76.1%) in group O and 81.0% (grade A: 38.1%) in group P (grade A: p < 0.001). CONCLUSIONS: The midterm angiographic results of CE with long arteriotomies and on-lay patch bypass grafting were better than the results obtained with the conventional pull-out method. This procedure was found to be safe and effective for complete revascularization in patients with a severely and diffusely diseased coronary artery.

Aged↗
PubMed2005

Minimal access via lower partial sternotomy for congenital heart defects.

To evaluate the invasiveness of a minimal access approach for simple congenital heart defects, and determine whether it can be regarded as a standard operation, 83 patients with an atrial septal defect and 73 with a ventricular septal defect underwent repair through a minimal skin incision and lower partial median sternotomy. There were no operative deaths, severe intraoperative complications, or conversion to full sternotomy. The clinical course of 106 patients was compared with that of 21 treated using a full sternotomy by the same surgeon; there were no significant differences, except in the operative time for ASD patients. The clinical courses of 2 minimal access subgroups (50 patients operated on by residents and 106 treated by the staff surgeon were compared; operative time, bypass time, ventricular fibrillation time (ASD repair), and cardiac arrest time (VSD repair) were significantly shorter in those operated on by the staff surgeon, but there was no difference in clinical course. The minimal access approach produced good cosmetic results, its invasiveness was similar to that of a full sternotomy, and it may be considered a standard operation for pediatric patients with septal defects.

Adolescent↗
PubMed2004

Structural scaffold of 18-crown-6 tetracarboxylic acid for optical resolution of chiral amino acid: X-ray crystal analyses and energy calculations of complexes of D- and L-isomers of tyrosine, isoleucine, methionine and phenylglycine.

To clarify the structural scaffold of (+)-18-crown-6 tetracarboxylic acid ((+)-18C6H4) for the optical resolution of a chiral amino acid, the crystal structures of its equimolar complexes with L- and D-isomers of tyrosine (Tyr), isoleucine (Ile), methionine (Met) and phenylglycine (PheG) were analysed by X-ray diffraction methods. (+)-18C6H4 took very similar conformations for all complexes. Although the chemical structure of (+)-18C6H4 is C2-symmetric, it took a similar asymmetric ring conformation of radius ca. 6.0 A. In all complexes, the amino group of chiral amino acids was located near the center of the ring and formed three hydrogen bonds and five electrostatic interactions with eight oxygen atoms of the ether ring and carboxyl groups. Also, the Calpha atom of chiral amino acids participated in Calpha-H...O interaction with the oxygen atom of (+)-18C6H4. In contrast, the carboxyl group of chiral amino acids did not directly interact with (+)-18C6H4. These results indicate that the structural scaffold of (+)-18C6H4 for the optical resolution of chiral amino acids is mainly based on the mode of interaction of (+)-18C6H4 with the amino and Calpha-H groups of chiral amino acids. The differences in interaction pattern and binding energy between the L- and D-isomers of each amino acid are discussed in relation to the chiral recognition of (+)-18C6H4.

Amino Acids↗
PubMed2004

Extensive thoracoabdominal aortic aneurysm repair using deep hypothermic bypass and circulatory arrest.

We sought to evaluate the safety and usefulness of deep hypothermic cardiopulmonary bypass with intervals of circulatory arrest for extensive thoracoabdominal aortic aneurysms. Between March 1994 and December 2002, 17 patients with Crawford type I and II were reviewed retrospectively. The patients were divided into two groups: group H (hypothermic circulatory arrest, n = 8) and group N (normothermic cardiopulmonary bypass, n = 9). In group H, in-hospital mortality was 12.5%, and that in group N was 11.1%. Operation times were similar between the two groups though the cardiopulmonary bypass time was significantly shorter in group N than in group H (p < 0.05). Postoperative paraplegia occurred in 1 patient of group N. Postoperative renal dysfunction occurred in none of group H except in 1 preoperative dialysis case, whilst it occurred in 6 patients of group N. Postoperative creatinine levels were significantly higher in group N than in group H. Three cases in group H required tracheostomy. Our experience with hypothermic cardiopulmonary bypass and circulatory arrest for diffuse type thoracoabdominal aortic aneurysm confirms the safety and efficacy of this technique. Although respiratory complications remain a problem, the technique is considered to be effective for renal protection.

Analysis of Variance↗
PubMed2003

Nuclear magnetic resonance studies for the chiral recognition of (+)-(R)-18-crown-6-tetracarboxylic acid to amino compounds.

Chiral recognition capability of (+)-(R)-18-crown-6-tetracarboxylic acid (18C6H(4)) to various amino compounds containing 16 amino acids, five alkyl amines, seven aminoalcohols and other amino compounds in nuclear magnetic resonance (1H-NMR) analysis was investigated. In general, amino compounds having an aromatic ring were well chiral recognized with 18C6H(4) compared with those having no aromatic ring. Effects of 18C6H(4) concentration and the kind of deuterated solvents (D(2)O, CD(3)OD and CD(3)CN) for measurement on the chiral recognition was investigated in detail. Concentration of 5 equivalent 18C6H(4) to the amino compounds was found to be sufficient for the chiral recognition. On the other hand, an effective deuterated solvent (D(2)O, CD(3)OD or CD(3)CN) for measurement was different in each compound. Distinguishment of 1.0% of the minor enantiomer (D-form) in L-alanine-beta-naphthylamide was found to be possible by 1H-NMR employing 18C6H(4) as a chiral shift reagent.

Amino Acids↗
PubMed2003

[Analysis of natural medicines by micellar electrokinetic chromatography (MEKC) (II)--determination of atractylenolide III in Atractylodis Rhizoma].

We have investigated a method to analyze the marker substance of natural medicines by employing capillary electrophoretic techniques such as micellar electrokinetic chromatography (MEKC). We previously reported a simple MEKC assay method for calycosin in Astragali Radix and its fluid extract. In this investigation, we analyzed the marker substance atractylenolide III in Atractylodis Rhizoma. Atractylenolide III was clearly separated from the other components in A. Rhizoma and its dried extract by simple solvent extraction with hexane and subsequent MEKC analysis with sodium dodecyl sulfate (SDS) within 10 min. Validation of the analytical procedures of the assay method was performed according to the Japanese Pharmacopoeia and International Conference on Harmonization guidelines. As a result, we confirmed that capillary electrophoresis, including MEKC, is a powerful method for estimating the quality of natural medicines and traditional Chinese medicines consisting of various components.

Chromatography, Micellar Electrokinetic Capillary↗
PubMed2003

Complete revascularization in patients with severe left ventricular dysfunction.

OBJECTIVE: This study evaluates whether patients with coronary artery disease and severely depressed left ventricular ejection fraction (LVEF) benefit from complete revascularization by multivessel coronary artery bypass. METHODS: From April 1994 to May 2002, 42 patients who underwent coronary artery bypass grafting (CABG) at our institution had impaired left ventricular (LV) function [an ejection fraction (EF) of 30% or less]. The average preoperative LVEF was 23.8%. The mean number of grafts was 4.6. Complete revascularization by multivessel bypass grafting was the goal for all patients. RESULTS: Thirty days mortality was 0 and hospital mortality was 2.4%. The mean graft patency rate for 35 (83%) patients at one month was 98.8%. The mean postoperative LVEF improved significantly, from 23.8% to 35.2% (p<0.05), and the New York Heart Association (NYHA) classification was improved in most patients. The Kaplan-Meier estimate of survival at 5 years was 83.1%, and that of the cardiac event-free rate at 5 years was 77.5%. CONCLUSION: For patients with poor LV function, complete surgical revascularization by multivessel bypass grafting can be performed safely, with satisfactory hospital mortality and long-term results.

Adult↗
PubMed2002

Enantiomer separation by capillary electrophoresis utilizing carboxymethyl derivatives of polysaccharides as chiral selectors.

Enantiomer separations of various drugs by capillary electrophoresis (CE) were investigated utilizing carboxymethyl (CM) derivatives of some polysaccharides. Three types of CM-polysaccharides, namely CM-dextran, -amylose and -cellulose were employed as chiral selectors in the CE enantiomer separation. Capability of enantiomer separation by these CM-polysaccharides was compared with that by polysaccharides without CM residues (i.e. native or neutral polysaccharides). Among three selectors employed, CM-dextran and -cellulose showed a relatively wide capability of enantiomer separation. Modification of polysaccharides seems to lead to the enhancement of the capability of enantiomer separation. Degree of substitution greatly affected the capability of enantiomer separation of these polysaccharide derivatives as in the beta-cyclodextrins derivatives.

Amylose↗
PubMed2002

In situ pericardium repair of pulmonary venous obstruction after repair of total anomalous pulmonary venous connection.

A 13-month-old boy with recurrent pulmonary venous obstruction (PVO) after repair of total anomalous pulmonary venous connection (TAPVC, Darling IIa + Ia) was treated successfully with in situ pericardium repair consisting of unroofing coronary sinus at 2 months. At 8 months, stenosis of the right upper and lower pulmonary veins (PV) and left lower PV were detected, and PVO was relieved via resection of the stenosis site and recutback. Echocardiography 3 months later showed obstructed bilateral PVs and connection between left PVs and vertical veins. At reoperation, we conducted in situ pericardium repair for right PVO and anastomosed left PVs to the left atrial appendage. The postoperative course was satisfactory. Echocardiography 12 months later showed no evidence of PVO, but cardiac catheterization 12 months later showed mild obstruction on the right side and normal venous drainage on the left. Although the long-term prognosis is unknown, this sutureless technique is effective in recurrent PVO.

Humans↗
PubMed2002

Early angiographic and clinical results of branch conduits attached proximally to left internal thoracic arteries.

BACKGROUND: We assessed the characteristics of composite branch conduits attached proximally to an in-situ left internal thoracic artery (LITA). METHODS: Sixty nine patients underwent coronary artery bypass grafting (CABG) using composite branch conduits. Overall 35 distal LITAs, 4 RITAs, 18 radial artery grafts (RAG), and 13 inferior epigastric artery grafts (IEA) (both the distal LITA and IEA were used in one patient) were used. Clinical and angiographic results were assessed. RESULTS: Patency of branch conduit was 97.1% in distal LITAs, 100% in RITAs, 100% in RAGs, and 90.9% in IEAs. All in-situ LITAs were patent. Ten branch conduits exhibited the string sign. The string sign was caused by competitive flow in seven patients. In three of seven patients with competitive flow, the string sign had resolved at one year after operation as the proximal stenosis of the native coronary artery increased in severity. CONCLUSIONS: The results of CABG using branch conduits were satisfactory. It is feasible to observe and follow patients with composite grafts exhibiting the string sign in the absence of ischemia.

Coronary Angiography↗