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Biomedical subjects

N Koyama

Publications and source records attributed to N Koyama.

At least 55 records · Page 3Linked to original sources
PubMed1999

Superior biocompatibility of heparin-bonded circuits in pediatric cardiopulmonary bypass.

BACKGROUND: Heparin bonding of pediatric cardiopulmonary bypass circuits may decrease activation of blood compartments as inflammatory responses. We studied the biocompatibility of heparin-bonded circuits in infant cardiac surgery. METHODS: Twenty-four infants undergoing elective cardiac surgery were randomly assigned to either a nonheparin-bonded control circuit (n = 12) or a fully heparin-bonded circuit (n = 12) including membrane oxygenator, reservoir, and all tubing. Blood samples were used to identify differences in complement activation and cytokine release between groups during and after cardiopulmonary bypass. The postbypass oxygenation index was also compared. RESULTS: The C3 activation product in the heparin-bonded group was significantly lower during (p < 0.01) and just after (p < 0.05) cardiopulmonary bypass. No statistically significant difference in C4 activation products was observed. Lower interleukin-6 and tumor necrosis factor-alpha were found immediately after cardiopulmonary bypass (p < 0.05) and a higher mean postbypass oxygenation index was also seen (p < 0.05) in the heparin-bonded group. CONCLUSION: We found that a heparin-bonded cardiopulmonary bypass circuit reduced inflammatory response and improved oxygenation in pediatric cardiac surgery. These results suggest that the superior biocompatibility of the bonded circuit may reduce pulmonary complications.

Cardiac Surgical Procedures↗
PubMed1999

Presence of Na+-stimulated P-type ATPase in the membrane of a facultatively anaerobic alkaliphile, Exiguobacterium aurantiacum.

It was found that a facultatively anaerobic alkaliphile, Exiguobacterium aurantiacum, possesses a membrane-bound ATPase, which was activated specifically by Na+. The Na+-stimulated ATPase activity reached a maximum value at 200 mM NaCl. In the presence of 200 mM NaCl, the activity was drastically reduced by vanadate, a potent inhibitor of P-type ATPase, with a half-maximal inhibition at 1 microM. Incubation of the membranes with [gamma-32P]ATP followed by acidic lithium dodecyl sulfate-polyacrylamide gel electrophoresis demonstrated the existence of two phosphorylated intermediates with apparent molecular masses of 60 and 100 kDa. Only phosphorylation of the 100-kDa polypeptide was inhibited by vanadate. The membrane extract containing Na+-stimulated ATPase, when reconstituted into soybean phospholipid vesicles, exhibited 22Na+ transport by the addition of ATP, which was inhibited by vanadate and gramicidin. It is likely that the Na+-stimulated ATPase belongs to P-type and is involved in Na+ transport.

Adenosine Triphosphatases↗
PubMed1999

Effect of growth pH on the phospholipid contents of the membranes from alkaliphilic bacteria

An aerobic alkaliphile YN-2000 and a facultatively anaerobic alkaliphile BL77/1 are able to grow over the wide pH range of 7-10.5. Net surface charges on the membranes from YN-2000 and BL77/1 were negative above pH 4, and the amounts were significantly increased when the bacteria were cultured at pH 10 as compared with those cultured at pH 7.5. Phospholipid contents of the membranes from both bacteria grown at pH 10 were much higher than those from the bacteria grown at pH 7.5. Phospholipids of the membranes from YN-2000 and BL77/1 were composed mainly of cardiolipin (CL), phosphatidylethanolamine (PE), and phosphatidylglycerol (PG). It is suggested that the increases by growth at pH 10 of negative charges on the membranes from the bacteria result mainly from the increases of acidic phospholipids such as CL and PG. Increases of phospholipid contents and/or negative charges on the membranes seem to contribute to the adaptation of YN-2000 and BL77/1 to an alkaline environment. http://link.springer-ny. com/link/service/journals/00284/bibs/39n5p270.html</HEA

Journal Article↗
PubMed1999

Elevated platelet activating factor in the tracheal aspirate at birth and signs of intra-uterine inflammation in infants with neonatal pulmonary emphysema.

UNLABELLED: To investigate the pathophysiology of the neonatal pulmonary emphysema, we assayed platelet activating factor (PAF) in the tracheal aspirates of the low birth weight infants. A total of 29 neonates (birth weight <1750 g) who required mechanical ventilation were enrolled. Tracheal aspirates were obtained within 48 h and blood samples collected within 24 h of life. PAF was assayed on the basis of its ability to cause aggregation of washed rabbit platelets. PAF was significantly elevated in four infants who showed pulmonary emphysema within the 1st week of life (median 24 pg/g lipid phosphorus, range 9.9-200) compared with those detected in the other three groups of infants; infants with respiratory distress syndrome (RDS) in whom chronic lung disease (CLD) did not develop (median 1.8 pg/g lipid phosphorus, range 0-30; P < 0.05), infants without RDS nor CLD (median 0.64 pg/g lipid phosphorus, range 0-14; P < 0.05) and infants with other types of CLD (median 1.1 pg/g lipid phosphorus, range 0-1.8; P < 0.01). The four infants who developed pulmonary emphysema within the 1st week of life, had significantly elevated serum IgM and neutrophilia at birth. The increased amount of PAF in the tracheal aspirates shows the presence of inflammation in the lung at birth. The elevated serum IgM level and neutrophilia indicate that the inflammation begins in utero. CONCLUSION: Our data suggest that neonatal pulmonary emphysema is caused by intra-uterine inflammation increasing platelet activating factor in the lungs. Platelet activating factor may play a role in aggravating the process of pulmonary emphysema.

Bronchoalveolar Lavage Fluid↗
PubMed1999

[Noonan syndrome associated with atrial septal defect, pulmonary stenosis, and completely unroofed coronary sinus without LSVC: a case report].

An eight-year-old boy, Noonan syndrome associated with ASD and PS, was referred to our department for surgical repair. During operation, the coronary sinus ostium was not found. Farther more exploration revealed completely unroofed coronary sinus without LSVC. The large ASD (confluent with coronary sinus ASD) was closed with a ePTFE patch. The pulmonary valve was thickened moderately and each commissure was adhesive, but not dysplastic. PS was released with commissurotomy and subpulmonary muscle resection. The postoperative course was uneventful and the patient discharged at 14 postoperative day. At present, he has been followed at outpatient without PS and any sign and symptom of myocardial hypertrophy.

Cardiac Surgical Procedures↗
PubMed1999

[Reoperation of tetralogy of Fallot for the transannular patch neo-intimal stenosis: a case report].

A 3-year-old male patient underwent right ventricular outflow tract reconstruction with a glutaraldehyde-preserved equine pericardium for tetralogy of Fallot. Because of progressive severe pulmonary restenosis with over systemic right ventricular pressure, tricuspid regurgitation, and abnormal high echoic shadow in the distal main pulmonary artery on echocardiogram, he required reoperation a year after the first correction. In the reoperative findings, the pseudointima was thickened heavily and detached from glutaraldehyde-preserved equine pericardial patch. The patch was removed and the right ventricular outflow was reconstructed widely to the pulmonary bifurcation with porcine pericardial patch again. Patho-histological findings showed foreign body giant cells and macrophages in the pseudointima. Four years after the reoperation, echocardiogram shows 41 mmHg for the right ventricular pressure and 22 mmHg for the pressure gradient of right ventricular outflow tract, and the patient is doing well now.

Cardiac Surgical Procedures↗
PubMed1998

Cloning and functional expression of human aquaporin8 cDNA and analysis of its gene.

The cDNA and the gene of human aquaporin8 (AQP8) were cloned from human testis cDNA and a genomic library, respectively. The AQP8 cDNA encodes 261 amino acids. The identity of the amino acid sequence to other aquaporins is highest with a plant water channel, gamma-TIP (40.4%), while AQP2 and AQP3 are 28.9 and 29.5% identical to human AQP8, respectively. The human AQP8 is only 74.9% identical to rat AQP8 and 76.0% identical to mouse AQP8. In Northern blot analysis, approximately 1.35-kb human AQP8 mRNA was expressed in pancreas and colon, but not in other tissues. Absence of human AQP8 in testis is noteworthy as rat AQP8 was abundantly expressed in testis. The expression of human AQP8 cRNA in Xenopus oocytes increased osmotic water permeability by 10-fold. AQP8 was not permeable to urea nor to glycerol. The AQP8 gene has five introns, and the locations of exon-intron boundaries were different from those of the other mammalian aquaporins, suggesting its separate phylogenetic origin.

Amino Acid Sequence↗
PubMed1998

Presence of Na(+)-stimulated V-type ATPase in the membrane of a facultatively anaerobic and halophilic alkaliphile.

It was found that a facultatively anaerobic and halophilic alkaliphile, M-12 (Amphibacillus sp.), possesses a Na(+)-stimulated ATPase in the membrane. The ATPase activity was inhibited by NO3- and SCN- which are the inhibitors of V-type ATPase, but not by azide and vanadate, inhibitors of F-type ATPase and P-type ATPase, respectively. Upon the incubation of the membrane in buffer containing ATP and MgCl2, several polypeptides were released from the membrane. Among them, two major polypeptides with apparent molecular masses of 79 and 55 kDa crossreacted with an antiserum against the catalytic units (subunits A and B) of V-type ATPase from Enterococcus hirae. The N-terminal amino acid sequences of the 79 and 55 kDa polypeptides showed high similarity to those of subunits A and B of V-type ATPase from Enterococcus hirae, respectively. M-12 is likely to possess a V-type Na(+)-ATPase.

Amiloride↗
PubMed1998

Heparan sulfate proteoglycans mediate a potent inhibitory signal for migration of vascular smooth muscle cells.

Migration of vascular smooth muscle cells (SMCs) is a key step in vascular remodeling and formation of pathological lesions in diseased arteries and may be controlled by extracellular matrix (ECM) and by factors that regulate ECM composition, such as platelet-derived growth factor (PDGF). In culture, PDGF-AB and -BB enhance but PDGF-AA (although having no effect alone) suppresses SMC migration stimulated by other PDGF isoforms. To determine whether the migration-inhibitory mechanism of PDGF-AA was mediated by ECM composition, we examined baboon SMC migration in a Boyden chamber assay using filters coated with different ECM proteins. PDGF-AA suppressed the PDGF-BB-induced migration of baboon SMCs on a filter coated with basement membrane proteins (Matrigel) and fibronectin but failed to inhibit cell migration on a type I collagen (Vitrogen)-coated filter. Fibronectin and fibronectin fragments that contain heparin-binding domains permitted PDGF-AA inhibition of cell migration, but a fragment lacking heparin-binding domains did not. Treatment of SMCs with heparin lyases II and III, but not with chondroitin ABC lyase, diminished the PDGF-AA-mediated inhibition of migration. PDGF-AA stimulated accumulation of proteoglycan (PG) in the cell layer more potently than did PDGF-BB, whereas the turnover of cell layer PG was unaffected by either PDGF-AA or -BB. Northern blot analysis revealed that PDGF-AA increased syndecan-1 mRNA expression more than did PDGF-BB, whereas both PDGF isoforms decreased perlecan expression. The changes in cell migration and PG synthesis induced by PDGF-AA were accompanied by changes in the morphology of SMCs. PDGF-AA dramatically induced the spreading of SMCs, whereas the heparin lyase treatment of PDGF-AA-stimulated cultures diminished cell spreading. The data suggest that PDGF-AA selectively modifies heparan sulfate PG accumulation on SMCs and thereby influences the interactions of SMCs with heparin-binding ECM proteins. These interactions, in turn, generate signals that suppress SMC migration.

Animals↗
PubMed1998

Peroxide reductase activity of NADH dehydrogenase of an alkaliphilic Bacillus in the presence of a 22-kDa protein component from Amphibacillus xylanus.

The NADH oxidase of Amphibacillus xylanus shows high NADH-peroxide reductase activity for hydrogen peroxide and alkyl hydroperoxides in the presence of a 22-kDa disulfide-containing protein component (Y. Niimura, L. B. Poole, and V. Massey, J. Biol.Chem. 270, 25645-25650, 1995). It was found that the membrane-bound NADH dehydrogenase of an alkaliphilic Bacillus (YN-1) involved in the respiratory chain also exhibits reductase activity for hydrogen peroxide and cumene hydroperoxide in the presence of the 22-kDa component from Amphibacillus xylanus. Vmax values for these substrates were as high as those of the NADH oxidase of A. xylanus. Although the 38-kDa protein produced by trypsin treatment of NADH dehydrogenase retains NADH dehydrogenase activity, it exhibited no peroxide reductase activity in the presence of the 22-kDa component from A. xylanus. The NADH dehydrogenase of YN-1 might not only catalyze electron flow from NADH to the respiratory chain, but also function for scavenging peroxide.

Bacillus↗
PubMed1998

Cryopreservation of mature bovine oocytes by vitrification in straws.

Experiments were conducted to determine optimal conditions for vitrification of in vitro matured bovine oocytes in straws. In the first series of experiments, the effects of stepwise addition before exposure of oocytes to vitrification solution consisting of 30% (v/v) ethylene glycol (EG) with 0.35 M sucrose was tested. The rates of morphological survival and cleavage of oocytes vitrified by the three-step addition procedure were higher than those vitrified by the one-step addition procedure. In the second series, the effect of the concentration of the vitrification solution was tested (20, 30, 40, and 50% EG, all with 0.35 M sucrose). The survival rates of oocytes vitrified in 20 and 30% EG were lower than those in 40 and 50% EG. The rates of cleavage and development to blastocysts of oocytes vitrified in 40% EG were the highest among the four groups. In the third series, the effect of duration of exposure of oocytes to 0.5 M sucrose (1, 5, and 10 min) at the first step during the three-step dilution was tested. Although there were no significant differences among the groups with respect to developmental competence of oocytes vitrified in 40% EG, the highest development rate (10%) to blastocysts was observed when oocytes were exposed to sucrose for 5 min. These data demonstrate that improvements to the concentration of cryoprotectant and addition procedures have critical effects on the developmental competence of oocytes vitrified in straws.

Animals↗
PubMed1998

[A successful valve repair case of isolated tricuspid regurgitation due to traumatic lacerated papillary muscle of the tricuspid valve].

A case of tricuspid valve regurgitation due to a non-penetrating chest trauma was presented. This case involves a 20-year-old man, who was admitted to a nearby hospital because of rib fracture, mandibular fracture, and hemorrhage of the left hemopneumothorax, caused by a traffic accident. Palpitation and chest discomfort were observed at admission time, but there was no follow-up. Tricuspid regurgitation was pointed out during surgery for the mandibular fracture, and he continued follow up treatment at an outpatient clinic. However his palpitation and chest discomfort worsened, and he was admitted to our department 8 month after injury. During surgery to repair the tricuspid valve, a papillary muscle rupture, valve cusp laceration, and anulus dilatation were found. We performed a papillary muscle repair (chorda tendineae reconstruction), valve cusp suture, and annuloplasty. Absence of the left pericardium was observed during the operation. We reported valve repair of traumatic tricuspid regurgitation which with papillary muscle rupture. Due to its rarity and the fact that there has been no reported cases of papillary muscle repair for traumatic tricuspid regurgitation in Japan, we used researched information on the subject.

Adult↗
PubMed1998

[A successful case report of one and one half ventricle repair for pure pulmonary stenosis in a 4-year-old girl].

A 4-year-old girl with pure pulmonary stenosis, hypoplastic right ventricle and atrial septal defect, underwent left modified Blalock-Taussig shunt at the age of 2 year. Her RVEDV was 62.7% of normal and TVD was 64.2% of normal at the age of 3 year. We observed development of right ventricle and performed simultaneously Glenn shunt and right ventricular outflow reconstruction (one and one half ventricle repair). Her general condition after operation became better. The size of tricuspid valve and right ventricle grew on Cardiac ultrasonography and catheterization examined after one year operation. In future, If the size of RV and TV might grow further, we should recommend her biventricular repair.

Child, Preschool↗
PubMed1998

[A case report of incomplete endocardial cushion defect with mitral stenosis in an elderly patient].

The following paper describes a mitral valve replacement (SJM 27 mm), the patch closure (EPTFE) of an ostium primum atrial septal defect and tricuspid annuloplasty (De Vega's method) in a 64-year-old female patient with an incomplete endocardial cushion defect and mitral stenosis. Surgery revealed thickened, mitral valve leaflets and the presence of a cleft, findings similar to those observed in case of rheumatic degeneration. Investigation of patient hemodynamics confirmed a diagnosis of Lutembacher syndrome and a lower with left ventricle volume. After surgery, the volume of left ventricle increased and the patients clinical course was uneventful.

Endocardial Cushion Defects↗
PubMed1998

[Surgical treatment of total anomalous pulmonary venous connection--clinical aspects of pulmonary venous obstruction].

During November 1986 and May 1997, 19 patients with total anomalous pulmonary venous connection (TAPVC) underwent repair surgery. 20 operations including two reoperations were performed. 8 of 19 patients were classified as Darling type Ia, 5 as type IIa, 4 as type III and 2 patients were type IV. Two patients were operated under emergency circumstances within 24 hours after admission, 7 patients were after a short term stabilization of 4.4 days, and the other 11 patients received surgical treatment after a mean of 8.8 days as scheduled cases. For the anostomosis, the common pulmonary venous chamber or the vertical vein was connected with the left atrium in type Ia and III cases; in type IIa and IV cases the cut-back method was performed. Persistent pulmonary hypertension and post-operative pulmonary venous obstruction (PVO) affected the post-operative clinical course. Persistent pulmonary hypertension caused the death of one patient with type IIa and III each, just after operation. One type IV patient died 50 days after operation. The autopsy revealed post-operative obstructions of the remote parts of the pulmonary veins on the anostomosis site. Two patients (type IIa, III) successfully underwent reoperation due to PVO. Post-operative cardiac catheterization was performed after 12 month in 12 cases. Persistent pulmonary hypertension was found in 4 patients, and a type III patient was reoperated because of stenosis of the anostomosis site. The other three patients had persistent pulmonary hypertension without any demonstrable PVO. Persistent pulmonary hypertension and PVO are combined as TAPVC complex. The difficulty to reoperated patients with persistent pulmonary hypertension caused by PVO is one major problem. So preoperative prevention of PVO by normalization the morphologic changes of the pulmonary veins by using drugs could be a different view point in TAPVC therapy after the initial operation.

Anastomosis, Surgical↗