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Biomedical subjects

A Sekiguchi

Publications and source records attributed to A Sekiguchi.

At least 37 records · Page 2Linked to original sources
PubMed1996

Usefulness of pulsatile bidirectional cavopulmonary shunt in high-risk Fontan patients.

BACKGROUND: A bidirectional cavopulmonary shunt has been performed for the high-risk Fontan patient. It is well known that in the presence of the bidirectional cavopulmonary shunt alone to secure pulmonary blood flow, the central pulmonary artery size decreases over time. We have performed pulsatile bidirectional cavopulmonary shunt (PBCPS), keeping pulmonary blood flow from the ventricle through the stenotic pulmonary valve, or a Blalock-Taussig shunt in patients who do not meet the criteria for the Fontan operation. METHODS: Eleven patients who underwent PBCPS between 1989 and 1993 were reviewed. We compared the results of cardiac catheterization immediately before PBCPS and during the postoperative observation period (310 +/- 257 days). RESULTS: Pulmonary blood flow and arterial oxygen saturation increased significantly after PBCPS (p = 0.01). Pulmonary artery area index showed a tendency to increase (p = 0.11). The mean number of risk factors for the Fontan procedure decreased significantly for 1.8 +/- 1.1 to 0.7 +/- 0.8 after PBCPS (p < 0.05). Overall, 5 of the 11 patients (45.5%) met the criteria for the Fontan procedure, and a fenestrated Fontan procedure was carried out in 4 of them. CONCLUSIONS: The PBCPS is useful for high-risk Fontan patients not only in the staged Fontan operation, but also as definitive palliation.

Child↗
PubMed1995

Pulmonary atresia with intact ventricular septum: long-term results of "one and a half ventricular repair".

BACKGROUND: Between 1982 and 1984, we successfully performed "one and a half ventricular repair" using a Glenn shunt for 3 patients with pulmonary atresia with intact ventricular septum. Here we review the 10-year follow-up results. METHODS: In these patients, the preoperative Z scores of the tricuspid valve diameters ranged from -5.2 to -6.5. Right ventricular outflow tract reconstruction combined with a Glenn shunt were performed in all patients. Cardiac catheterization was done at least 10 years post-operatively. RESULTS: All 3 patients have maintained New York Heart Association functional class I status for more than 10 years. Angiography in 2 patients confirms sufficient left pulmonary artery pressure with pulsatile blood flow and good right ventricular contraction. A pulmonary arteriovenous fistula has developed in 1 patient. CONCLUSIONS: Although the lower limits of the tricuspid valve diameter for "one and a half ventricular repair" using a cavopulmonary shunt have not yet been determined, we successfully performed this procedure in 3 patients with severely hypoplastic right ventricles and tricuspid valve diameter Z scores of less than -5.0. The results up to 10 years postoperatively are acceptable.

Cardiac Surgical Procedures↗
PubMed1995

[Surgical repair of complete atrioventricular septal defect: annuloplasty by using a smaller VSD patch].

Recent policy for the intracardiac repair of complete atrioventricular septal defect (CAVSD) is demonstrated on the basis of the following theoretical background. In the normal heart, the originating portion of the ascending aorta and the crux intrude between the mitral and tricuspid orifices each from the anterior and from the posterior, separating both the orifices together with a short fibrous septal junction. In CAVSD, however, the common A-V orifice takes an elliptic form without any septal junction. It is considered beneficial, therefore, to surgically produce a short septal junction by using a smaller patch to close the ventricular portion of the AVSD. When the left lateral leaflet is larger, two leaflets valve plasty is suggested and when it is smaller, three leaflets valve plasty is suggested to reconstruct the left-sided A-V valve, although competence of the valve leaflets must be finally secured by doing repeated water injection tests. The size of the orifices of the reconstructed left-sided as well as right-sided A-V valve should also be confirmed not to be stenotic by using Hegar sizers. Since 1991, we have applied this surgical concept in 7 patients with CAVSD. Postoperatively, there was no left A-V valve regurgitation in one and slight regurgitation remained in 6 patients. The result is considered to be satisfactory. Although one patient died due to PH crisis, the cause of death was not related to valve regurgitation.(ABSTRACT TRUNCATED AT 250 WORDS)

Child, Preschool↗
PubMed1994

[Superior vena cava-right atrial appendage direct anastomosis for repair of partial anomalous pulmonary venous connection to superior vena cava].

Successful repair was performed for a 7-year-old male with a diagnosis of partial anomalous pulmonary venous connection (PAPVC) to superior vena cava (SVC) and superior sinus venosus atrial septal defect (ASD). The SVC was divided above the orifice of the anomalous pulmonary vein and the cephalad end of the SVC was anastomosed directly to the right atrial appendage. A patch was used to divert pulmonary venous flow from the orifice of the SVC through superior sinus venosus ASD into the left atrium. Postoperative course was uneventful with normal sinus rhythm. There was no evidence of vena caval or pulmonary venous obstruction. At 3-month after surgery, sinus node function was confirmed to be normal by electrophysiological study. This is useful alternative method for repair of PAPVC to high or middle SVC.

Anastomosis, Surgical↗
PubMed1993

Cross-ligation and exchange reactions catalyzed by hairpin ribozymes.

The negative strand of the satellite RNA of tobacco ringspot virus (sTobRV(-)) contains a hairpin catalytic domain that shows self-cleavage and self-ligation activities in the presence of magnesium ions. We describe here that the minimal catalytic domain can catalyze a cross-ligation reaction between two kinds of substrates in trans. The cross-ligated product increased when the reaction temperature was decreased during the reaction from 37 degrees C to 4 degrees C. A two-stranded hairpin ribozyme, divided into two fragments between G45 and U46 in a hairpin loop, showed higher ligation activity than the nondivided ribozyme. The two stranded ribozyme also catalyzed an exchange reaction of the 3'-portion of the cleavage site.

Base Sequence↗
PubMed1993

Induction and the possible mechanism of ventricular tachycardia after catheter ablation with direct current shocks in dogs.

Cathodal DC shocks (150-J) were administered via the His bundle to 20 closed-chest dogs, and in a further three dogs 25-J cathodal shocks were given via the left ventricular endocardium. In 18 dogs, including three that underwent left ventricular ablation, Holter electrocardiograms were recorded from 1 to 7 days after ablation, and 4 weeks after ablation. There were frequent episodes of sustained ventricular tachycardia (VT) from the first few hours after ablation to 4 days after ablation in all dogs, but both the rate and the coupling interval of VT were variable. In five conscious dogs stimulated 1 day after ablation, it was difficult to induce and terminate VT repeatedly. There was a direct relationship between the paced cycle length and the interval of the last paced beat to the initiating VT beat in three out of four dogs. In the fourth dog there was an inverse relationship. There was no transient entrainment with ventricular burst pacing during VT in any of the four dogs tested. The effects of lidocaine (2-3 mg.kg-1), verapamil (0.2-0.4 mg.kg-1), and propranolol (0.2 mg.kg-1) on VT were tested within 2 days of ablation in 10 conscious dogs. In general, both lidocaine and verapamil terminated VT, and propranolol slowed VT. In conclusion, VT soon after ablation possibly results from triggered activity, although abnormal automaticity cannot be ruled out.

Animals↗
PubMed1993

[Successful treatment of fungal endocarditis and mediastinitis after fenestrated Fontan operation--a case report].

Fenestrated Fontan operation was performed in a 19-year-old male with a diagnosis of right isomerism syndrome. Postoperatively, fungal endocarditis due to Candida Albicans and mediastinitis by Methicilin resistant Staphylococcus Aureus (MRSA) occurred. For Candida endocarditis, combined surgery and medical treatment with amphotericin B was effective. MRSA mediastinitis was successfully treated by continuous closed irrigation with 0.5% povidone-iodine solution. This is the 17th reported case of fungal endocarditis after open heart surgery in Japanese literature.

Adult↗
PubMed1993

[A role of valvuloplasty in surgical treatment of isolated tricuspid regurgitation].

Seven surgical cases of isolated tricuspid regurgitation were reviewed. From pathological point of view, the patients were classified into three groups. Two were due to abnormalities of subvalvular system, four to annular dilatation and one to anomalous leaflet. Among four cases of annular dilatation, two were diagnosed as dilated cardiomyopathy. In one, it was very rare myopathy confined to right ventricle. Three cases, two subvalvular and one leaflet abnormalities, underwent valvuloplasty which included chordal reconstruction using Gore-Tex suture. Among annular dilatation group, three underwent valve replacement (two with mechanical valve and one with bioprosthetic valve), while fourth underwent annuloplasty. When We look at 89 surgical patients with secondary tricuspid regurgitation, thrombosed mechanical valve was seen in two cases, one of them necessitating re-valve replacement. On the other hand, late results of tricuspid annuloplasty with Carpentier-Edwards ring was excellent without re-operation. Although isolated tricuspid regurgitation has very complicated pathological features, we now think it very important to manage to repair regurgitant tricuspid valve utilizing all available techniques including redundant valve tissue resection, chordal reconstruction, and annuloplasty, thus avoiding valve replacement especially with mechanical valve.

Adolescent↗
PubMed1992

Cross-ligation and exchange reaction of RNA catalyzed by hairpin ribozymes.

The catalytic domain in the minus strand of the satellite RNA of tobacco ringspot virus (sTobRV(-)) assumes a hairpin-like secondary structure. This ribozyme catalyzes a cross-ligation reaction between substrate RNAs of different lengths. We constructed ribozymes to probe the activities of ligation and RNA fragment exchange.

Base Sequence↗
PubMed1992

[A case report: successful direct closure of atrial septal defect in isolated right ventricular hypoplasia].

We experienced a surgery for an isolated right ventricular hypoplasia with atrial septal defect (ASD). The patient, 3 1/2-year-old girl, underwent direct closure of ASD. Preoperatively right ventricular end diastolic volume was 18 ml or 22 ml including trabecular portion by angiocardiographic examination. It was almost a half of normal. We performed intraoperative ASD occlusion test using a Foley 12 F balloon catheter before surgical closure of ASD. Postoperatively, mild right pleural effusion was found, but it disappeared soon with a use of diuretics. ASD occlusion test was safe and useful for estimating surgical closure of ASD. Postoperative cardiac catheterization revealed slight increase of right atrial pressure. It is necessary to follow up her condition carefully.

Child, Preschool↗
PubMed1991

Mutagenesis and self-ligation of the self-cleavage domain of the satellite RNA minus strand of tobacco ringspot virus and its binding to polyamines.

Several mutants for the minus strands of the self-cleaving domain of the satellite RNA of tobacco ringspot virus have been synthesized by joining chemically synthesized oligoribonucleotides with RNA ligase. Kinetic properties of the enzyme strands (50 nucleotides) against substrates (15-mer and 18-mer) were investigated. Structural properties of the unpaired part in the cleavage region were estimated from mutagenesis. The catalytic domain alone was proved to be responsible for the rejoining reaction of cleaved substrates. It was also found that the ribozyme could be divided into two strands without loss of activity. Effects of concentration of magnesium ion and polyamines on the cleavage reaction for the two-stranded ribozyme are also reported.

Base Sequence↗
PubMed1990

Identification of the amino acid residues involved in an active site of Escherichia coli ribonuclease H by site-directed mutagenesis.

The amino acid residues essential for the catalytic activity of ribonuclease H (RNase H) from Escherichia coli (E. coli) were identified by site-directed mutagenesis. It has been proposed by computer analysis that E. coli RNase H has homologous amino acid sequence with the RNase H domains of various retroviral reverse transcriptases (RTs) (Johnson, M. S., McClure, M. A., Feng, D. F., Gray, J., and Doolittle, R. F. (1986) Proc. Natl. Acad. Sci. U. S. A. 83, 7648--7652). Of the eight highly conserved residues examined, Asp10, Glu48, and Asp70 were found to be crucial for RNase H activity. Determination of the kinetic parameters for the mutated enzymes using the chemically synthesized nonanucleotide duplex as a substrate demonstrated that these residues are involved in the catalytic site rather than the substrate-binding site. These residues are fully conserved in the amino acid sequences of not only retroviral RTs but also hepadnaviral, plant viral and retrotransposon RTs. This strongly suggests that they are also involved in the active site of these RTs and RT related enzymes.

Amino Acid Sequence↗
PubMed1990

Rotation-advancement flap method for correction of partial anomalous pulmonary venous drainage into the superior vena cava.

Three patients with partial anomalous pulmonary venous drainage into the superior vena cava underwent repair by a rotation-advancement flap method. The technique consisted of atrial partitioning, enlargement of the superior vena cava, and protection of sinus node function. Follow-up studies of all patients were done between 12 and 15 months after the operation. The superior vena cava was not stenosed and its diameter was normal, as demonstrated by cavograms. Pulmonary venous return appeared normal on angiograms, and sinus node function was normal by electrophysiologic studies.

Adult↗
PubMed1989

The response of digitalized canine ventricle to programmed stimulation: a study on triggered activity arrhythmias in the whole heart.

Triggered activity (TA) has recently received increased attention as a mechanism responsible for cardiac arrhythmias. However, few studies have shown TA in the intact heart. In an ouabain-treated dog's heart we have shown: (a) overdrive acceleration, (b) a concordant relationship between the postpacing interval (PI) and pacing cycle length (CL), and (c) a discordant relationship between the PI and number of paced beats necessary to induce TA. These findings appear to agree with the distinctive characteristics of TA arrhythmias elucidated in previous in vitro studies and suggest TA rather than a reentrant tachycardia. In addition, it is possible that this heart preparation could be considered as a suitable model for the study of TA arrhythmias. These results were obtained using a programmed stimulation protocol in this dog model: (1) Following single programmed ventricular stimulation during sinus rhythm, a repetitive ventricular response (RVR) of more than 3 beats occurred in only 20% of hearts. The relationship between PI and the coupling interval (CI) of the extrastimulus was concordant in 80% (12/15) and discordant in 13% (2/15) of all experiments. The PI-CI relationship was influenced by the mutual relationship between the stimulating, recording, and originating sites of TA. (2) RVR of more than 3 beats was induced by consecutive overdrive ventricular stimulation during sinus rhythm (78%). In addition, the PI-pacing CL relationship was concordant (100%). (3) The transient termination of sustained VT that occurred spontaneously after administration of a large dose of ouabain was seen in only 15% of the cases after a single programmed premature ventricular stimulation. The return cycle-CI relationship was biphasic in 75% (15/20) experiments and discordant in 25% (5/20) of the experiments. (4) The termination of spontaneous sustained VT by overdrive ventricular stimulation occurred in only 8% of the cases. Transient overdrive acceleration of VT occurred after overdrive pacing (53%). In contrast, overdrive suppression occurred in only 13%. Thus, the characteristics of TA arrhythmias observed in the whole heart preparations differed, in some respects, from those obtained by in vitro studies. These quantitative observations could suggest a differentiation, based on probability, between TA and the reentrant mechanism that would respond to programmed stimulation in a similar manner. The differentiation between reentrant and triggered ventricular tachycardia can be made with reasonable assurance using these programmed stimulation techniques.

Animals↗
PubMed1989

[A case of metastatic lung tumor of the colon cancer with ova of schistosoma japonicum in the resected lung specimen].

A 69-year-old man underwent right middle lobectomy because of the tumor lesion in the right middle lung. He had ever been in Celebes and China (riverside area of the Yangtze), the infected area of schistosomiasis japonica, for military service during the World War II. Resected lung specimen was carefully examined at the department of pathology in our hospital. Several ova of Schistosoma japonicum were discovered scattered in the specimen, and the pathological feature of the lung lesion was revealed to be metastasis of the sigmoid colon cancer which was resected 4 years ago at a certain hospital. The ova of Schistosoma japonicum were also distributed near the colon lesion. Recently in Japan, it is said, acute infected case of schistosomiasis japonica has been ceased, however, in cases of chronic stage of this disease, hepatoma or lower intestinal cancers are still discovered through the careful follow up study.

Adenocarcinoma, Papillary↗