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Biomedical subjects

Y Sawa

Publications and source records attributed to Y Sawa.

At least 235 records · Page 13Linked to original sources
PubMed1989

[A case report of Rastelli operation in 2-month-old infant with truncus arteriosus (type II)].

A two-month-old girl with heart failure from truncus arteriosus (Collett & Edwards Type II) underwent a total correction by the Rastelli procedure using 12-mm-diameter Hancock valved conduit. The orifice of pulmonary arteries was closed from inside without detachment of the pulmonary artery from truncus. The distal anastomosis of the conduit was made to left pulmonary artery. Primary sternal closure was difficult and delayed closure was performed using splint with a resin plate. The skin was primarily closed using bilateral advancement myocutaneous flaps. Complete closure of the sternum was made on the 11th postoperative day. A rotation flap of the right abdominal rectal muscle was used to cover the partially necrotic skin over the sternum. The patient had persistent respiratory and cardiac problems, but was discharged 14 months after surgery.

Blood Vessel Prosthesis↗
PubMed1989

[Arterial switch operation for simple transposition of the great arteries in infancy].

Five infants (22-42 days of life) underwent arterial switch operation for simple transposition of the great arteries under deep hypothermic cardio-pulmonary bypass. Three babies required prostaglandin E1 infusion to keep ductus arteriosus opened widely before surgery. Balloon atrioseptostomy was necessary in 0-10 days of life in all babies because of poor condition. Left to right ventricular peak pressure ratio ranged from 0.75 to 0.86, preoperatively. Four of the five survived the operation, and one died of coronary insufficiency because of kinking of the implanted coronary artery. Hypothermic circulatory arrest was used in three (38-41 minutes). Aortic cross clamp time was 70-100 minutes, and cold crystalloid cardioplegia was given only one time just after aortic clamp in 3 babies. Single dose of cardioplegia protected left ventricular muscle well in babies with transposition of the great arteries as same as multiple dose method used in those with ventricular septal defect.

Humans↗
PubMed1989

Comparison of single dose versus multiple dose crystalloid cardioplegia in neonate. Experimental study with neonatal rabbits from birth to 2 days of age.

Thirty-five isolated hearts from newborn rabbits (aged birth to 2 days) were subjected to 120 minutes of ischemia at 15 degrees C with high potassium crystalloid cardioplegia. They were divided into four groups according to the method of cardioplegic administration: group C (preischemic control, n = 9), group S (single dose, n = 10), group M-1 (multiple dose, infused every 40 minutes, n = 7), and group M-2 (multiple dose, infused every 20 minutes, n = 9). After 30 minutes of reperfusion, the heart rate, coronary flow, creatine kinase release, percent water content, and myocardial ultrastructural scores for mitochondrial damage and intracellular edema were compared among the four groups. All of these parameters except coronary flow were significantly poorer in group M-2 than in groups C and S (p less than 0.05). The mitochondrial damage and intracellular edema scores were significantly poorer in group M-1 than in group C (p less than 0.05). No significant differences in these two scores were seen between group S and group C and between group S and group M-1. These results indicate that the single dose method of administering crystalloid cardioplegia may provide better myocardial protection than the multiple dose method in the neonate.

Animals↗
PubMed1989

[Experimental and clinical assessment of myocardial protective effect of a prostacyclin analogue (OP 41483)].

The beneficial effects of a stable prostacyclin analogue (PGI2-A), OP 41483 against myocardial ischemic injury were experimentally and clinically evaluated. In 31P-NMR study, the preischemic treatment with PGI2-A prevented myocardial ATP depletion of rat hearts which were subjected to 20 min global ischemia. In patients with congenital heart disease, the PGI2-A of 300 ng/ml was added to the glucose-insulin-potassium cardioplegia (PGI2-group), and this group was compared to control group without PGI2-A in terms of postoperative maximal leakage of CPK-MB (maxCPK-MB). In patients under 1 yr or patients over 1 yr with aortic cross clamp time exceeded 120 min, the maxCPK-MB was significantly (p < 0.05) reduced as compared to the control. This stable PGI2 analogue has shown significant myocardial protective effects experimentally and also in clinical setting.

Animals↗
PubMed1988

Intermediate filaments of hepatocytes and biliary epithelial cells in bile duct obstruction: transmission and scanning electron microscopy study.

The cytoskeletons of hepatocytes and biliary epithelial cells in bile duct ligated rate livers were investigated by transmission and scanning electron microscopy. The three dimensional organization of the intermediate filaments (IFs) of hepatocytes and biliary epithelial cells was clearly demonstrated by scanning electron microscopy. Cell borders and dilated bile canaliculi were well preserved after perfusion with detergent solution. A very dense filamentous network of IFs was seen throughout the cytoplasm, especially around the dilated bile canaliculi and at the cell borders. IFs in biliary epithelial cells were more numerous compared with hepatocytes. Morphometric analysis showed that the IFs of hepatocytes significantly (p greater than 0.001) increased in amount in bile duct ligated rats. The IFs of biliary epithelial cells showed no significant changes in bile duct ligated rats compared to controls. These results suggest that the increase in IFs in hepatocytes results from the adaptation of the hepatocytes to the stress imposed by bile duct ligation. It may be that the resulting intracanalicular pressure and back diffusion of bile induces a metaplastic change in hepatocytes so that they acquire more IFs to function like the bile duct epithelium to conduct bile flow.

Animals↗
PubMed1988

Scanning electron microscopy of the hepatocyte cytoskeleton in human liver tissue.

Portions of eight human livers taken by wedge biopsy or needle biopsy were extracted with 0.5% Triton X-100 and then studied by scanning electron microscopy and immunoelectron microscopy. The wedge-biopsy specimens were perfused with the detergent solution. Needle-biopsy specimens were quickly frozen and cracked and then the cracked tissue was immersed in the detergent solution. The three-dimensional filament network of hepatocytes was visualized. A dense network which consisted of intermediate filaments and microfilaments was observed within the cytoplasm of hepatocytes. These filaments were better preserved in the needle biopsies which were quick-frozen and cracked before extraction than in the wedge biopsies. Variation in the amount of the cytoskeletal filaments was less prominent in the hepatocytes treated by rapid freezing. It is concluded that freeze-cracking is the most favorable method for the study of cytoskeletal pathology in various liver diseases in man.

Biopsy↗
PubMed1988

Glutamine synthetase from a cyanobacterium, Phormidium lapideum: purification, characterization, and comparison with other cyanobacterial enzymes.

Glutamine synthetase has been purified to homogeneity from cell extracts of a non-N2-fixing filamentous cyanobacterium, Phormidium lapideum. The subunit molecular weight of the enzyme was determined as about 59,000 by sodium dodecyl sulfate gel electrophoresis. Electron micrographs of the Phormidium enzyme revealed a two-layered structure of regular hexagons (12 subunits per molecule), which markedly resembles the three-dimensional polypeptide backbone structure of the Salmonella typhimurium glutamine synthetase established by X-ray crystallography (Almassy, Janson, Hamlin, Xuong, & Eisenberg (1986) Nature 323, 304-309). The N-terminal amino acid sequence of the Phormidium enzyme shows very high similarity with that of the enzyme from an N2-fixing cyanobacterium, Anabaena 7120; 18 residues are common in 23 residues compared. Strong immunocross-reactions between the antibody against the purified Phormidium glutamine synthetase and other cyanobacterial enzymes except the Anacystis enzyme were observed. The apparent Michaelis constants for NH3, L-glutamate, and ATP were determined to be 0.29, 7.4, and 1.7 mM, respectively. Divalent metal ions such as Mg2+ and Mn2+ activated the enzyme in the biosynthetic reaction, whereas various amino acids and glutamate analogs strongly inhibited the enzyme.

Amino Acid Sequence↗
PubMed1988

[Changes in monoamine metabolites in the nucleus accumbens and locomotor activity by reserpine: an in vivo microdialysis study].

The effect of ip administration of reserpine (2 mg/kg) on the monoamine metabolites 3,4-dihydroxyphenyl acid (DOPAC), homovanillic acid (HVA), 5-hydroxy-indoleacetic acid (5-HIAA) was estimated in the freely moving rat by intracerebral dialysis in the nucleus accumbens. Locomotor activity was measured simultaneously by Automex. Locomotor activity tended to increase during the first 2 hours. On the other hand, a significant reduction of locomotor activity was found during the 3rd-5th hour period of the experiment. HVA-total (conjugated + free) and 5-HIAA were elevated significantly (P less than 0.05) during the 3rd-5th and the 5th-6th hour periods, respectively. However, the difference of DOPAC between both groups did not reach statistical significance throughout the experiment. During the 3rd-5th hour of experiment, the change of behavior and HVA were inversely correlated. This might suggest that an HVA level in the dialysate is a good index of dopamine metabolism in the nucleus accumbens after reserpine treatment.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1988

Experimental and clinical study of crystalloid cardioplegic solution in neonatal period and early infancy. Effects of calcium and prostacyclin analogue.

The effects of calcium and a prostacyclin (PGI2) analogue in the glucose-insulin-potassium (GIK) cardioplegic solution for the neonatal period and early infancy were evaluated. The assessment was based mainly on semiquantitative scoring of mitochondrial damage and intracellular edema in postreperfusion biopsies. Experimentally, 45 isolated perfused newborn rabbit hearts (age, 0-2 days) underwent 2 hours of global ischemia at 15 degrees C with a single dose of GIK cardioplegic solution and were subsequently assigned to three groups: Group 1 hearts (n = 15) were infused with basic GIK cardioplegic solution alone (no added calcium, but measured at 0.1-0.2 mM/l); Group 2 hearts (n = 15) received GIK cardioplegic solution with calcium (1.2 mM); and Group 3 hearts (n = 15) received GIK cardioplegic solution with calcium and a PGI2 analogue (OP-41483, 300 micrograms/l). Group 3 hearts showed significantly lower mitochondrial damage and intracellular edema scores than did Group 1 and Group 2 hearts (p less than 0.05). Hemodynamic measurement (aortic flow and coronary flow) results after reperfusion were also better in Group 3 hearts than in the hearts of the other two groups (p less than 0.05). In the clinical study with 18 infants who were less than 3 months old, the same three cardioplegic solutions were used. Group 2 (n = 6) and Group 3 (n = 5) infants showed significantly lower mitochondrial damage scores than did Group 1 (n = 7) infants. Group 3 infants also showed significantly lower intracellular edema scores than did Group 1 and Group 2 infants.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Antiarrhythmic effects of a new drug, E-0747, on canine ventricular arrhythmia models.

Antiarrhythmic effects of a new antiarrhythmic drug, E-0747, were examined using four canine ventricular arrhythmia models: digitalis-, adrenaline- and two-stage coronary ligation-induced arrhythmias and a newly developed locally-induced digitalis arrhythmia. The minimum effective plasma concentration of E-0747 was determined for the first three arrhythmia models. E-0747 suppressed those arrhythmias, and the minimum effective plasma concentrations for arrhythmias induced by digitalis, adrenaline, 24 hr coronary ligation, and 48 hr coronary ligation were 1.4 +/- 0.6, 1.8 +/- 0.4, 1.6 +/- 0.4 and 2.2 +/- 0.2 micrograms/ml, respectively (mean +/- S.D., n = 5-10). The aforementioned minimum effective plasma concentrations of E-0747 for these arrhythmias were almost equal to the reported concentration in vitro to suppress the Na channels of isolated canine ventricular tissues. The class 1 property of E-0747 was also shown in a newly developed locally-induced digitalis arrhythmia. Thus E-0747 suppresses arrhythmia by inhibiting Na channels of cardiac cells and is expected to become a clinically useful antiarrhythmic drug.

Animals↗
PubMed1987

Ultrastructural assessment of the infant myocardium receiving crystalloid cardioplegia.

The effectiveness of cold crystalloid potassium cardioplegia was evaluated in 26 infants (age 27 days to 17 months, 7.5 +/- 5.2 months, mean +/- SD) who underwent intracardiac repair for various cardiac lesions. A myocardial biopsy sample was obtained before aortic cross-clamping (AXC) and 20 min after release of AXC (AXC time 22 to 161 min, mean 68 +/- 37 min), and semiquantitative assessment of the mitochondrial structure was made by scoring. The post-AXC score was significantly higher than the pre-AXC score (1.1 +/- 0.6 vs 0.4 +/- 0.4, p less than .001) for the whole group. Patients receiving preoperative catecholamine support had higher pre- and post-AXC scores than those who did not (pre-AXC score 0.7 +/- 0.4 vs 0.2 +/- 0.3, p less than .01; post-AXC score 1.4 +/- 0.5 vs 1.0 +/- 0.5, p less than .05). Infants less than 3 months old (n = 7) and those 3 to 12 months old (n = 11) had higher pre AXC scores than infants over 12 months old (n = 8). With respect to post-AXC score, only those less than 3 months old had significantly higher values than the other infants. These results indicate that the myocardial injury was not fully prevented by crystalloid potassium cardioplegia in infants, and that infants with preoperative heart failure and less than 3 months old appear to have increased myocardial susceptibility to ischemic injury under cardioplegia.

Aorta↗
PubMed1986

Purification and characterization of yeast L-kynurenine aminotransferase with broad substrate specificity.

L-Kynurenine aminotransferase [L-kynurenine:2-oxoglutarate aminotransferase (cyclizing), EC 2.6.1.7] has been purified to homogeneity and crystallized from cell-free extracts of a yeast, Hansenula schneggii, grown in a medium containing L-tryptophan as an inducer. The enzyme has a molecular weight of about 100,000 and consists of two subunits identical in molecular weight (52,000). The enzyme exhibits absorption maxima at 280, 335, and 430 nm, and contains 2 mol of pyridoxal 5'-phosphate per mol of enzyme. The enzyme-bound pyridoxal 5'-phosphate shows negative circular dichroic extrema, in contrast with other pyridoxal 5'-phosphate acting on L-amino acids. In addition to L-kynurenine and alpha-ketoglutarate, which are the most preferred substrates, a large number of L-amino acids and alpha-keto acids can serve as substrates; the extremely broad substrate specificity is the most characteristic feature of this yeast enzyme. The enzyme activity is significantly affected by both carbonyl and sulfhydryl reagents. Certain dicarboxylic acids such as adipate and pimelate act as competitive inhibitors. Addition of various substrate amino acids to the culture medium results in the inductive formation of aminotransferases which are immunochemically indistinguishable from L-kynurenine aminotransferase.

Amino Acids↗
PubMed1986

Localization of carbamoylphosphate synthetase and aspartate carbamoyltransferase in chloroplasts.

The localization of carbamoylphosphate synthetase (CPSase) and aspartate carbamoyltransferase (ACTase), the first two enzymes of the pyrimidine biosynthetic pathway, in chloroplasts was investigated. In dark-grown radish (Raphanus sativus) seedlings, light induced a prominent increase in CPSase activity, but had little effect on ACTase activity. Both enzymes were found in chloroplasts isolated from radish cotyledons and leaves of spinach (Spinacia oleracea), soybean (Glycine max), and corn (Zea mays). The higher activity of ACTase relative to CPSase is discussed in relation to the instability of carbamoylphosphate, the product of the CPSase, and to the control of pyrimidine synthesis. Based on these results, the function of CPSase and ACTase in chloroplasts is discussed.

Journal Article↗