Biomedical subjects

F Yamamoto

Publications and source records attributed to F Yamamoto.

At least 73 records · Page 4Linked to original sources

PubMed1996

[The effect of coenzyme Q10 and cold cristalloid cardioplegia on hypothermic global ischemia].

Coenzyme Q10 (CoQ10, ubiquinone) has been shown to be protective against myocardial ischemia/reperfusion induced injury. The purpose of this study was to investigate the effect of CoQ10 added to cold cristalloid cardioplegia on hypothermic ischemia and normothermic reperfusion using an isolated working rat heart. Hearts (n = 6-9/group) from male Wistar rats were aerobically (37 degrees C) perfused (20 min) with bicarbonate buffer. This was followed by a 3-min infusion of St. Thomas' Hospital cardioplegic solution containing various concentrations of CoQ10 (0, 1, 3, 6, 12, and 58 mumol/L). Hearts were then subjected to 180 min of hypothermic (20 degrees C) global ischemia and 35 min of normothermic (37 degrees C) reperfusion (15 min Langendorff, 20 min working). Ventricular fibrillation (Vf) upon reperfusion was irreversible in the 12 and 58 mumol/ L CoQ10 groups (4/6 and 3/6, respectively). In the hearts which Vf upon reperfusion was not irreversible, the percent recovery of aortic flow (%AF) was 43.3 +/- 5.4% (n = 9) in the control group versus 31.6 +/- 7.7% (n = 6), 38.0 +/- 12.0% (n = 6), 27.2 +/- 6.9% (n = 6), 31.3% (n = 2), and 30.4 +/- 14.2% (n = 3) in the 1, 3, 6, 12, and 58 mumol/L CoQ10 groups, respectively. Creatine kinase leakage during Langendorff reperfusion tended to be greater in the 12 and 58 mumol/L CoQ10 groups than in the control group. Thus, CoQ10 in the cold cristalloid cardioplegic solution induced irreversible Vf upon reperfusion and failed to improve functional recoveries following hypothermic global ischemia.

Animals↗

PubMed1995

Extent of aortopulmonary collateral blood flow as a risk factor for Fontan operations.

Between November 1987 and January 1990, 33 patients (tricuspid atresia, 9 patients; mitral atresia, 3; single ventricle, 15; others, 6) underwent Fontan operations. The rate of blood flow returning to the heart during aortic cross-clamping was measured as an indication of the extent of development of aortopulmonary collateral arteries. Percent cardiac return (calculated by dividing the blood flow rate returning to the heart by the cardiopulmonary bypass blood flow rate and expressing the value as a percentage), were 1% to 9%, 7 patients; 10% to 19%, 11; 20% to 29%, 9; 30% to 39%, 4; 40% to 49%, 1; and 50% to 59%, 1 patient. Percent cardiac return showed a significant correlation with postoperative mean systemic venous pressure (r = 0.6, p < 0.01). In those patients in whom percent cardiac return was more than 33%, the mean systemic venous pressure after operation was high (more than 17 mm Hg), and none of these patients survived. To predict percent cardiac return preoperatively, the conventional indices of systemic ventricular volume, pulmonary artery area index, arterial blood oxygen saturation, pulmonary blood flow index, and pulmonary vascular resistance were analyzed. None of these showed significant correlation with percent cardiac return. However, all the patients who had a high percent cardiac return (more than 30%) also had both high arterial blood oxygen saturation (more than 75% in room air) and small pulmonary artery area index (less than 55%). In addition, the age at operation showed good correlation (r = 0.6, p < 0.01) to percent cardiac return.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1995

A bicuspid pulmonary valve is not a contraindication for the arterial switch operation.

There are no obvious criteria concerning the optimal repair for complete transposition with bicuspid pulmonary valve if neither the organic changes in the valve nor the pressure gradient between the left ventricle and the pulmonary trunk are severe. Instead of intraatrial switching or intraventricular rerouting in such circumstances, we have proceeded to the arterial switch procedure in 6 patients with an adequate diameter of the pulmonary valve (greater than 100% of the calculated normal aortic orifice). Postoperative catheterization (at approximately 8 months after the procedures) showed no pressure gradient between the left ventricle and the neoaorta except for a finding of 34 mm Hg difference in 1 patient who had undergone simultaneous subpulmonary myotomy. Echocardiography (7 years later in the longest follow-up) has shown no more than slight regurgitation across the bicuspid neoaortic valve, with no progressive increase of blood velocity across the valve. From these results in the middle term, we conclude that the arterial switch procedure remains an option of choice for patients with initially bicuspid pulmonary valve, providing there is no severe subpulmonary stenosis.

Aorta↗

PubMed1995

What factors affect ventricular performance after a Fontan-type operation?

Postoperative conditions after a Fontan-type operation, particularly as they affect results in the early term, are thought to depend on factors such as the state of pulmonary circulation and ventricular function. In this study, we attempted to determine the factors that influence ventricular characteristics in the middle term after Fontan-type procedures. Catheterization was performed at a mean of 15 months after operation in 57 patients with univentricular atrioventricular connection who underwent the operation between 1.0 and 22.6 years of age. End-diastolic volume, end-systolic volume, ejection fraction, and end-diastolic pressure of the systemic ventricle were analyzed together with an estimation of the systemic flow index. These parameters were influenced significantly by the presence of atrioventricular valve insufficiency. The morphologically left ventricle showed a better ejection fraction than did the morphologically right ventricle, whereas the systemic flow index was greater in patients undergoing total cavopulmonary connection than in those receiving an atriopulmonary connection. Young age was significantly associated with a better postoperative contractility, whereas the potential for impaired ventricular compliance was suggested in several patients undergoing operation after 4 years of age. On the basis of our results, we conclude that total cavopulmonary connection performed at a young age should be the surgical procedure of choice and that atrioventricular insufficiency must be treated properly at, and even after, the initial definitive repair.

Adolescent↗

PubMed1995

Biventricular repair in cardiac isomerism. Report of seventeen cases.

Ninety-three patients with cardiac isomerism were treated surgically from July 1985 to June 1991. Among them, three patients with right and 14 with left isomerism underwent biventricular repair. Ages ranged from 4 months to 41 years (mean 4.8 years). Anatomic repair was accomplished in 15 patients and functional repair with the right ventricle used as the systemic ventricle in two patients. Methods of atrial septation to separate pulmonary venous flow from systemic venous flow included atrial partition with a straight patch in seven patients, intraatrial rerouting with a tailored baffle in five, and a Mustard-type atrial switch in five. One hospital death (5.8%) and two late deaths (12%) occurred. Two patients required reoperation (12%), one reconstruction of a stenotic systemic venous connection and one mitral valve replacement because of incompetence. Surgically induced complete atrioventricular block was not observed in any of the patients. Optimal atrial septation offers the possibility of biventricular repair for patients with acceptable intraventricular structure.

Abnormalities, Multiple↗

PubMed1995

Genomic organization of human histo-blood group ABO genes.

We have isolated human genomic DNA clones encompassing 30 kbp of the histo-blood group ABO locus. The locations of the exons have been mapped and the nucleotide sequences of the exon-intron boundaries have been determined. The human ABO genes consist of at least seven exons, and the coding sequence in the seven coding exons spans over 18 kb of the genomic DNA. The exons range in size from 28 to 688 bp, with most of the coding sequence lying in exon 7.

ABO Blood-Group System↗

PubMed1995

Physiological, morphological and anatomical responses of Fraxinus mandshurica seedlings to flooding.

Two-year-old Fraxinus mandshurica Rupr. var. japonica Maxim. seedlings were flooded to 8 cm above soil level for 70 days. The flooding treatment altered the growth, morphology, stem anatomy and ethylene production of the seedlings. Although flooding did not affect height growth, it stimulated diameter growth of the submerged stems by increasing both the number and size of wood fibers produced; however, the thickness of the cell walls of the wood fibers was reduced by flooding. In response to the flooding treatment, the seedlings formed abundant hyperhydric tissues, originating from the vicinity of lenticels on the surface of the flooded stems, and adventitious roots, which grew through the hyperhydric tissues. Aerenchyma tissues were observed in the bark of the adventitious roots. The flooding treatment did not affect dry weight increment of leaves and stems, but it reduced the total dry weight increment of the root system even though it promoted adventitious root formation. Flooding also enhanced ethylene production in the submerged portions of stems. The potential roles of flood-induced ethylene in cambial growth and adventitious root formation in flooded plants are discussed.

Journal Article↗

PubMed1995

Molecular genetics of the ABO histo-blood group system.

Molecular genetic study of the histo-blood group ABO system has elucidated the allelic basis of this genetic locus. Comparison of the nucleotide sequence has identified in the coding region differences which change amino acid sequences of the glycosyltransferases coded by these genes. Effects of the differences (mutations) on the specificity and activity of the glycosyltransferases have been examined.

ABO Blood-Group System↗

PubMed1995

ABO blood group genotype and plasma von Willebrand factor in normal individuals.

von Willebrand factor (vWF) is a multimeric plasma protein with ABO (H) blood group sugar chains. We investigated a total of 330 plasmas from normal individuals having various ABO genotypes, with special reference to vWF antigen and its platelet glycoprotein-Ib-related biological activities, termed ristocetin cofactor (RCof) and botrocetin cofactor (BCof). RCof reflects the biological activity of higher vWF multimers, while BCof reflects that of vWF of multimers of all sizes. Plasmas from normal individuals carrying one O gene (genotypes AO and BO) had slightly, but proportionally lower levels of vWF antigen, RCof, and BCof than those carrying no O gene (genotypes AA, AB, and BB). Normal plasmas from individuals carrying two O genes (genotype OO) showed much lower values for these parameters than the other plasmas, as previously reported. However, multimeric analysis of plasma vWF antigen revealed no differences among the different genotypes.

ABO Blood-Group System↗

PubMed1995

[Sarcoplasmic reticular calcium release and myocardial protection--effects of ryanodine and cold cristalloid cardioplegia on hypothermic global ischemia].

Myocardial rapid cooling is known to result in sarcoplasmic reticular (SR) calcium release. SR calcium release during an infusion of cold cardioplegic solution may contribute to myocardial protection against hypothermic global ischemia. We have, therefore, investigated using the isolated working rat heart preparation to determine the effect of cold cristalloid cardioplegic solution (K+ = 16 mmol/L) containing ryanodine on myocardial injury due to hypothermic global ischemia. Hearts (n = 6-12/group) from male Wistar rats were aerobically (37 degrees C) perfused (20 min) with bicarbonate buffer (Ca2+ = 2.4 mmol/L). This was followed by a 3 min infusion of St. Thomas' Hospital cardioplegic solution (20 degrees C) containing various concentrations of ryanodine. Hearts were then subjected to 180 min of hypothermic (20 degrees C) global ischemia and 35 min of normothermic (37 degrees C) reperfusion (15 min Langendorff, 20 min working). The recoveries of aortic flow were 46.4 +/- 3.7% in the ryanodine free controls versus 50.8 +/- 5.1, 50.6 +/- 4.8, 53.1 +/- 5.9, 59.4 +/- 1.9, 50.5 +/- 3.2 and 31.8 +/- 6.1% in the 0.18, 0.88, 1.31, 1.75, 10.00 and 100.00 nmol/L ryanodine groups, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1995

[The effects of glucose and insulin upon functional recovery in the rat heart preserved by continuous perfusion with St. Thomas' Hospital cardioplegic solution].

UNLABELLED: The aim of this study was to determine the effect of the continuous perfusion with Krebs-Henseleit bicarbonate buffer (KHBB) solution or St. Thomas' Hospital cardioplegic solution (ST solution) containing glucose and insulin upon the post-preservation recovery in the isolated rat heart. METHODS: Hearts from male Wistar rats (n = 6/group) were subjected to working perfusion with KHBB solution for measurement of cardiac function. They were continuously perfused (1) with KHBB solution or ST solution for 12 hours at 20 degrees C, (2) with ST solution for 12 hours at 37 degrees C, 20 degrees C or 4 degrees C, (3) with ST solution or ST solution containing glucose (9 mmol/L) for 12 hours at 20 degrees C or 4 degrees C, and (4) with ST solution containing glucose (9 mmol/L) or ST solution containing glucose (9 mmol/L) and insulin (10 U/L solution) for 20 hours at 20 degrees C. This was followed by 15 min of Langendorff perfusion and 20 min of working perfusion with KHBB solution. During the second working perfusion after preservation, cardiac function was measured again. RESULTS: (1) Percent recoveries of cardiac output (%CO) preserved with KHBB and ST solution were 44.9 +/- 4.0 and 57.7 +/- 3.8%, respectively (p < 0.05). (2) %CO after preservation with ST solution at 37, 20, 4 degrees C were 0*, 57.7 +/- 3.8 and 74.4 +/- 2.2*%, respectively (*p < 0.05 vs the 20 degrees C group). (3) At 20 degrees C, glucose addition to ST solution increased %CO to 76.5 +/- 2.4% from 57.7 +/- 3.8% in glucose-free ST solution group (p < 0.05). However, at 4 degrees C, glucose addition to ST solution was rather harmful and decreased %CO to 61.4 +/- 2.8% from 74.4 +/- 2.2 in glucose-free ST solution group (p < 0.05). (4) The addition of insulin to the glucose-containing ST solution resulted in a significant increase in %CO from 24.6 +/- 4.0% in the insulin-free solution to 69.2 +/- 2.0%. CONCLUSIONS: Our results indicate that 1) ST solution might be better than KHBB solution for a continuous perfusion medium of myocardial preservation, and 2) at 20 degrees C, the addition of glucose and insulin to the ST solution could be beneficial for the continuous infusion as a method of preservation, however, at 4 degrees C, these addition might be harmful, suggesting the temperature dependence in the utility of energy substrate.

Animals↗

PubMed1995

Effects of ornithine on the electroretinogram in cat retina.

PURPOSE: To study the acute effects of L-ornithine hydrochloride on the function of cat retina in vivo. METHODS: A small amount of ornithine was administered intravitreously or intravenously. Changes in retinal function were monitored by vitreal electroretinogram (ERG) and intraretinal ERG with K(+)-selective microelectrodes. RESULTS: Intravitreal injections (0.2 to 0.5 M; 15 microliters) of ornithine caused a decrease in the standing potential and the vitreal ERG c-wave amplitude. The ERG c-wave decreased continuously during a 5-hour period. Intravenous injection (0.2 M; 10 ml) of ornithine also diminished the c-wave. Intraretinal recording showed that the amplitudes of the retinal pigment epithelium (RPE) component and the Müller cell component of the ERG c-wave were reduced after intravitreal injection. The light-evoked [K+]o decrease in the subretinal space did not change. The change in transepithelial resistance contributed little to the decrease in the c-wave. CONCLUSION: These results demonstrated that ornithine selectively affects the c-wave and suggested that it affects RPE and Müller cells directly without affecting photoreceptors.

Animals↗

PubMed1995

[The effects of Ebselen upon post-ischemic functional recovery in rat heart].

The effects of Ebselen (DR-3305) upon cardiac function and CK leakage with or without ischemia reperfusion insults were investigated in this isolated working rat heart study. In order to evaluate the effects of Ebselen upon cardiac function, it was administrated to the isolated rat heart with Langendorff perfusion for 15 min at 100 cmH2O. Cardiac functions such as aortic and coronary flow, heart rate and aortic pressure, before and after Ebselen treatment, were measured and expressed as percent of the control value. The coronary resistance was significantly reduced in 100 nM, 500 nM and 1000 nM of Ebselen pretreatment with dose dependent manner. However pretreatment with 1000 nM of Ebselen significantly decreased cardiac output with significant increase of CK leakage. The myocardial protective effects of Ebselen in the cardioplegia or reperfusate were investigated under conditions of normothermic ischemia. After measuring preischemic cardiac functions, the St. Thomas' Hospital cardioplegic solution was infused for 3 min followed by 35 min of global ischemia at 37 degrees C. Hearts were then aerobically reperfused for 15 min in the Langendorff mode. Subsequently, cardiac function was measured and expressed as percent of the preischemic control value. Ebselen addition to the St. Thomas' cardioplegic solution did not possess any myocardial protective effects, although addition to reperfusate possess the protective abilities at a concentration of 10 nM. From these data, Ebselen, which was one of the free radical scavenger, had the myocardial protective effects if it was added to reperfusate at a concentration of 10 nM.

Animals↗

PubMed1995

[Effect of CoQ10 on myocardial ischemia/reperfusion injury in the isolated rat heart].

It has been reported that CoQ10, ubiquionone, may have a protective effect on the mitochondrial injury induced by myocardial ischemia and reperfusion during open heart surgery. The purpose of this study was to investigate whether CoQ10 may enhance myocardial protection when given before ischemia, during ischemia or during reperfusion in the isolated working rat heart. Hearts (n = 6-9/group) from male Wistar rats were aerobically (37 degrees C) perfused (20 min) with bicarbonate buffer. In the first series of studies, this was followed by a 3 min infusion of St. Thomas' Hospital cardioplegic solution containing various concentrations of CoQ10. Hearts were then subjected to 39 min of normothermic (37 degrees C) global ischemia and 35 min of reperfusion (15 min Langendorff, 20 min working). The percent recovery of aortic flow (%AF) was 50.5 +/- 3.3% in the CoQ10 free controls versus 55.9 +/- 4.4, 62.1 +/- 3.1*% (*p < 0.05) in the 29, 44 and 58 mumol/L CoQ10 groups, respectively. Creatine kinase (CK) leakage during Langendorff reperfusion had a tendency to decrease in the 58 mumol/L group. In the second series of studies, 3 min of cardioplegia without CoQ10 and 38 min of ischemia (37 degrees C) were followed by a 15 min Langendorff reperfusion with 0 or 58 mumol/L of CoQ10 and 20 min working reperfusion. %AF was 53.2 +/- 2.7 and 39.2 +/- 7.1% in the 0 and 58 mumol/L CoQ10 groups, respectively. CK leakage had a tendency to increase in the 58 mumol/L group.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1995

[Diltiazem abolishes the effect of ryanodine in St. Thomas' Hospital cardioplegic solution on the post-ischemic functional recovery].

Calcium-induced calcium release (CICR) from sarcoplasmic reticulum (SR) may contribute to calcium depletion of SR during the infusion of cardioplegic solution, which may protect the intracellular calcium overload observed during myocardial reperfusion. We have, therefore, investigated (1) the ability of ryanodine-containing cardioplegic solution to enhance myocardial protection and (2) the influence of diltiazem, L-type calcium channel blocker, on the ryanodine-enhanced cardioprotective effect in the isolated working rat heart. Hearts (n = 6-8/group) from male Wistar rats were aerobically (37 degrees C) perfused (20 min) with bicarbonate buffer (Ca2+ = 2.4 mM). This was followed by a 3 min infusion of St. Thomas' Hospital cardioplegic solution containing (1) 0 nmol/L of ryanodine or (2) 1.75 nmol/L of ryanodine combined with various concentrations of diltiazem (0, 0.13, 0.25 and 0.50 mumol/L). Hearts were then subjected to 40 min of normothermic (37 degrees C) global ischemia and 35 min of reperfusion (15 min Langendorff, 20 min working). (1) The recovery of aortic flow (%AF) was 52.2 +/- 3.5% in the ryanodine-free group. (2) %AF was 72.0 +/- 1.4%, 50.0 +/- 2.6*, 61.7 +/- 3.2* and 58.3 +/- 2.8*% in the 0, 0.13, 0.25 and 0.50 mumol/L diltiazem groups, respectively (*p < 0.05 vs the 0 mumol/L diltiazem group). Creatine kinase (CK) leakage during Langendorff reperfusion was less in the 0 mumol/L diltizaem (plus 1.75 nmol/L ryanodine) group than the ryanodine-free group.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1994

A comparative study usefulness of magnetic resonance imaging in the diagnosis of acute cholecystitis.

The utility of magnetic resonance imaging (MRI) in the diagnosis of acute cholecystitis was evaluated in 72 consecutive individuals (5 healthy, 13 with chronic cholecystitis and silent gallbladder stones, 43 without biliary or diffuse liver disease, and 11 with acute cholecystitis and gallbladder stones) with a 0.5-T superconducting unit. On the T1-weighted (500/20) and less T1-weighted axial spin-echo images (620/25), the liver/gallbladder signal intensity ratio (mean +/- SD) was 2.5 +/- 0.51 (n = 5) and 1.8 +/- 0.29 (n = 8) in acute cholecystitis; 0.9 +/- 0.42 (n = 6) and 1.0 +/- 0.29 (n = 9) in chronic cholecystitis; and 0.9 +/- 0.14 (n = 5) and 0.8 +/- 0.19 (n = 43) in normal gallbladder, respectively. Our results indicate that the liver/gallbladder signal intensity ratio on the T1-weighted image may be a simple and reliable indicator for the diagnosis of acute cholecystitis; we suggest further investigation to confirm these results.

Acute Disease↗

PubMed1994

A case report of MR imaging of traumatic hemobilia.

The diagnosis of hemobilia is difficult. Computed tomography and ultrasonography generally yield only contributory information about blood or clots in the gallbladder but cannot demonstrate bleeding. This case report shows that magnetic resonance imaging (MRI) can not only demonstrate traumatic hemobilia in the gallbladder, and its origin, but can also determine active bleeding from liver lacerations and hematoma.

Adolescent↗

PubMed1994

Prevention of lung injury during open heart operations for congenital heart defects.

To elucidate free radical-induced lung injury associated with open heart operations for congenital heart defects, we studied 23 such patients. Maximum plasma chemiluminescence level (a marker of peroxylipids) in patients with pulmonary hypertension (n = 8) was higher than in patients with cyanotic disease (n = 8) (1,115.4 +/- 189.9 versus 728.8 +/- 48.3 counts; p < 0.05). There was a significant correlation between the maximum chemiluminescence level and preoperative pulmonary to systemic arterial pressure ratio (r = 0.929; p < 0.05). To investigate the effect of allogeneic leukocytes, we compared pulmonary hypertensive patients without allogeneic leukocyte transfusion during operation (n = 7) with the group with pulmonary hypertension. Both maximum chemiluminescence level during bypass (712.4 +/- 24.9 versus 1,115.4 +/- 189.9 counts; p < 0.05) and percent decrease in pulmonary arterial pressure after bypass (44.7% +/- 6.2% versus 28.2% +/- 4.5%; p < 0.05) were significantly improved, suggesting that depletion of leukocytes decreased the lung injury induced by free radical reaction.

Adolescent↗