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Biomedical subjects

F Yamamoto

Publications and source records attributed to F Yamamoto.

At least 109 records · Page 6Linked to original sources
PubMed1993

Molecular genetic analysis of the ABO blood group system: 3. A(X) and B(A) alleles.

We have employed a PCR approach to determine the nucleotide sequences of the coding region in the last two coding exons of the histo-blood group ABO genes from one A(X) and one B(A) individual. Compared with A1 alleles, the (A(X)) allele has a single nucleotide substitution (T-->A at nucleotide 646) resulting in an amino acid substitution (phenylalanine-->isoleucine at amino acid 216). Compared with B alleles, the B(A) allele has two nucleotide substitutions (T-->C at nt. 657 and A-->G at nt. 703) resulting in an amino acid substitution (serine-->glycine at aa. 235). The amino acid substitution resulting from this B(A) allele is located at the second of the four amino acid substitutions which discriminate human A and B transferases, and the amino acid residue (glycine) is identical to that of A transferase suggesting the involvement of this amino acid or its surrounding area for the recognition and/or binding of the donor nucleotide sugars.

ABO Blood-Group System↗
PubMed1993

Molecular genetic analysis of the ABO blood group system: 4. Another type of O allele.

We have encountered an allele which seems to be another type of O allele at the human histo-blood group ABO locus. We have determined the nucleotide sequence of this allele over the coding region in the last two coding exons. This allele does not possess the single-nucleotide deletion found common among all the O alleles previously analyzed. Compared with A1 allele, this allele has three nucleotide substitutions resulting in two amino acid substitutions. The introduction of these amino acid substitutions into the A1 transferase expression construct apparently abolished the enzymatic activity of A1 transferase.

ABO Blood-Group System↗
PubMed1993

Effects of ischemia-reperfusion on light-evoked alkalinization outside rod photoreceptors in the cat retina.

The effects of ischemia-reperfusion on the light-evoked alkalinization, which reflects the metabolism of rod photoreceptors, were studied in the dark-adapted cat retina in vivo. We recorded the pH value in the extracellular space surrounding rod photoreceptors with double-barreled H(+)-selective microelectrodes. The light-evoked alkalinizations at the outer nuclear layer were diminished during reperfusion after 10-30 min of ischemia which was induced by an increase of the intraocular pressure above the arterial systolic pressure. This result suggests that the rod metabolism might be suppressed during reperfusion after ischemia.

Animals↗
PubMed1993

Effects of iodate on intraretinal b and c waves of the cat electroretinogram.

In 12 cats, the intravenous and intravitreal administrations of sodium iodate (SI) were performed to examine the effects on b and c waves of electroretinogram in the dark-adapted retina. The intravitreal SI (0.5-3.5 mM) produced the complete suppression of intraretinal b waves without remarkable changes of slow PIII and light-evoked [K+]o decrease in the subretinal space. Intravenous SI (30 mg/kg) also showed the suppression of intraretinal b waves. SI not only acted as a poison to the retinal pigment epithelium but also might block the post-synaptic response.

Animals↗
PubMed1993

Growth potential after root replacement of the right and left ventricular outflow tracts.

A successful operation for acute and severe aortic regurgitation after balloon valvuloplasty together with mitral regurgitation is described in a 9-month-old infant. Aortic root replacement was performed using a pulmonary autograft, while the right ventricular outflow tract was reconstructed with an interposed left atrial appendage posteriorly and a heterologous pericardial patch anteriorly. Mitral valve reconstruction was also effectively accomplished. This combination of right and left ventricular outflow tract reconstruction has a good potential for growth and may provide a solution for the future in infants.

Aorta, Thoracic↗
PubMed1993

[Direct gallstone dissolution therapy with GS-100].

We have developed GS-100, a new direct dissolving drug with strong dissolution property for cholesterol stone by supplementing d-limonene, a dissolvent used since 1974, with 30% medium-chain monoglyceride (MCM). The new drug was applied in 23 patients with gallbladder stones and three with bile duct stone. The presumptive analysis of the composition of the stones was drawn from the CT recordings. As non-invasive therapies, methyl tert-butyl ether (MTBE) dissolution and extracorporeal shock wave lithotripsy (ESWL), which are commonly used in Europe and America, have been reported as being favourable; however, GS-100 is superior in respect to safety and applicative dimension, suggesting of the possibility of using GS-100 as an important drug in the non-invasive therapy for gallstone in the near future.

Adult↗
PubMed1993

[Surgical management of tetralogy of Fallot with absent pulmonary valve in infancy].

Between November, 1987 and May, 1990, definitive operation was performed in 7 infants for tetralogy of Fallot with absent pulmonary valve. Preoperative respiratory failure was serious in 5 patients and semi-emergency operation was done. Surgical procedure consisted of closure of ventricular septal defect, reconstruction of right ventricular outflow tract using heterograft valved pericardial roll and plication of aneurysmally dilated pulmonary artery with or without pulmonary artery suspension in 5 infants with severe respiratory distress and heart failure, operated on 26 days to 5 months of age. In the other two less symptomatic infants, operated on at 13 months of age, reconstruction of right ventricular outflow tract was performed by transannular bovine pericardial patch with monocusp. There were no operative death and six infants are doing well 6 months to 3 years postoperatively, but one patient died of prolonged respiratory infection and respiratory failure one year after operation. Postoperative pulmonary arteriogram revealed a 42 to 61 (mean 54) percent reduction in right and left pulmonary artery size in 3 patients who underwent extensive plication of pulmonary artery. We suggest that definitive plication with or without suspension of pulmonary artery, together with closure of ventricular septal defect and reconstruction of right ventricular outflow tract is supposed to eliminate air way obstruction.

Bioprosthesis↗
PubMed1993

Intraventricular repair for Taussig-Bing anomaly.

Among 41 patients with Taussig-Bing anomaly who underwent intracardiac repair, 10 patients were treated by intraventricular rerouting repair. The ages at operation ranged form 1 month to 8 years (average 2 years 3 months). Primary repair was done in four (average age 2 years 7 months), and repair was done after pulmonary artery banding in six patients (average age 2 years 2 months). The relationship of the great arteries was side by side in nine patients and oblique in one. After extensive resection of the infundibular septum, a distance of 8 to 18 mm from the tricuspid ring or chordae to the pulmonary valve was obtained (24% to 71% of total circumference for the subaortic route). The subaortic route was created to obtain an internal diameter at least equal to that of the aortic route. Tricuspid chordal or papillary muscle reattachment was performed in two patients. There were no early or late deaths. Follow-up ranged from 1 year 4 months to 22 years 3 months (average 5 years 8 months), and reoperation was required in one patient for residual pulmonary stenosis. The intraoperative pressure gradient between the left ventricle and aorta was 0 to 24 mm Hg (average 10.3 mm Hg), and postoperative study showed the gradients to be less than 19 mm Hg (n = 8). The age at operation, left ventricular-aortic pressure gradient, and postoperative tricuspid regurgitation were not significantly affected by the presence of severe hypertrophy of the infundibular septum (n = 4). These results indicate that intraventricular rerouting may be feasible in most patients who have the Taussig-Bing anomaly with side-by-side or similar relationships of the great arteries, and the age and conal anatomic variations do not appear to be significant limiting factors.

Cardiac Catheterization↗
PubMed1993

[Clinical application of recombinant human SOD for the protection of ischemia reperfusion injury during open heart surgery].

We have applied recombinant human superoxide dismutase (RH-SOD) to prevent ischemia reperfusion injury in the patients who received open heart surgery. Twenty-four patients were divided into 2 groups; group A had no treatment as control and group B received bolus injection of RH-SOD (35,000 IU/kg) into cardiopulmonary bypass 5 minutes before reperfusion. Arterial and coronary sinus blood was collected to measure chemiluminescence (ChL) value, SOD activity, lactate and pyruvate level, and several parameters of myocardial oxygen metabolism after reperfusion. Arterio-venous difference of ChL value showed the tendency of less ChL generation of the heart in group B compared with those in group A. But no other parameters showed significant difference between the two groups. Our data suggested that this way of the administration of RH-SOD failed to improve the myocardial protection during open heart surgery. Further investigation, such as dose response study, might be required to determine whether RH-SOD possess beneficial effects or not in the clinical setting.

Heart Arrest, Induced↗
PubMed1993

[A case report of successfully corrected 26 days old infant of tetralogy of Fallot with absent pulmonary valve].

A female infant weighing 2.4 kg had respiratory distress at birth. She became dyspneic and hypercapnic and required intubation with assisted ventilation 11 days after birth. Because cardiac failure and respiratory failure did not improve, she underwent total correction at 26 days old, which consisted of VSD closure, right ventricular outflow tract reconstruction with valved porcine pericardial roll (VPR) and plication of both pulmonary arteries. She was weaned from the ventilator 11 days after operation and discharged at 12 weeks of age. One year later, reoperation was successfully performed for the replacement of the stenotic VPR with a transannular patch.

Blood Vessel Prosthesis↗
PubMed1993

Effects of intravenous iodoacetate and iodate on pH outside rod photoreceptors in the cat retina.

PURPOSE: Effects of intravenous iodoacetate (a glycolysis inhibitor) and iodate (a metabolism inhibitor selective to retinal pigment epithelium) on light-evoked alkalinizations and hypoxia-induced acidifications were studied in the dark-adapted cat retina, in vivo, to learn about pH regulation. METHODS: pH was recorded in the extracellular space surrounding rod photoreceptors with double-barrelled H(+)-selective microelectrodes. RESULTS: Intravenous infusion of 5 mg/kg iodoacetate-induced alkalinizations in the outer nuclear layer and suppressed both light-evoked and hypoxia-induced pH responses immediately. Iodate injection (30 mg/kg) produced acidifications in the subretinal space and affected light-evoked alkalinizations gradually but not hypoxia-induced acidifications. CONCLUSIONS: These results suggest that rods glycolysis plays an important role in both light-evoked and hypoxia-induced pH responses. And the retinal pigment epithelium may have little concern with light-evoked alkalinizations except that it plays an important role in regenerating the rhodopsin to be needed for the light responses of photoreceptors. Furthermore, the finding of the intravenous-iodoacetate-induced alkalinization in the outer nuclear layer supports that acid production by rods in the dark is originated from glycolysis to support the dark current. The iodate-induced acidification in the subretinal space indicators that the retinal pigment epithelium might actively transport acids from the subretinal space to the choroid.

Animals↗
PubMed1992

Animal histo-blood group ABO genes.

Sequences homologous to the human histo-blood group ABO genes are present in the genomic DNA of various mammals. We have PCR-amplified, subcloned, and sequenced a portion of these genes from several species of primates and found high conservation of the nucleotide as well as the deduced amino acid sequences during evolution.

ABO Blood-Group System↗
PubMed1992

Photosensitized formation of 8-hydroxydeoxyguanosine in cellular DNA by riboflavin.

Photosensitized formation of 8-hydroxydeoxyguanosine (oh8dG) in DNA by riboflavin has recently been shown in vitro. The present study describes the formation of oh8dG in cellular DNA by photo-irradiation of cultured mammalian cells in the presence of riboflavin. Formation of oh8dG was dependent on the concentration of riboflavin as well as the duration of photoirradiation. These results suggest that photosensitized formation of oh8dG in DNA by riboflavin may be involved in photocarcinogenesis.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed1992

Human histo-blood group A2 transferase coded by A2 allele, one of the A subtypes, is characterized by a single base deletion in the coding sequence, which results in an additional domain at the carboxyl terminal.

We have identified a possible mutation which characterizes A2 alleles (a minor subtype of A) at the human histo-blood group ABO locus based on polymerase chain reaction (PCR) of genomic DNA, followed by nucleotide sequencing of the amplified fragments. The A2 subtype has a single base deletion near the carboxyl terminal. As a result of frame-shifting, A2 transferase possesses an extra domain. Introduction of this single base deletion into the A1 transferase cDNA expression construct drastically decreased the A transferase activity in DNA-transfected HeLa cells.

Alleles↗
PubMed1992

A useful cholesterol solvent for medical dissolution of gallstones.

Dissolution of cholesterol gallstones by direct instillation of an agent into the biliary tract has been considered an alternate to surgical procedures. We developed an excellent direct solubilizer by combining d-limonene and medium-chain monoglyceride. This mixture enhances the advantages of each individual solvent and minimizes the disadvantages. In vitro experiments were done to determine the viscosities and the cholesterol dissolving rates of various combinations, and in vivo experiments were conducted to study their irritation effects on tissues. The optimal combination was a 3:2 mixture of d-limonene and medium-chain monoglyceride. It could quickly dissolve cholesterol gallstones with minimal or no observable side effect.

Animals↗
PubMed1992

New surgical technique for total-defect aortopulmonary window.

A new technique is described to repair aortopulmonary window with total defect in an 8-day-old baby. Because we expected the future growth of aorta, we used the anterior wall of the pulmonary artery as a large flap to reconstruct the posterolateral aortic wall. An equine pericardial patch was used to repair the defect in the pulmonary artery. This is a logically effective method for aortic reconstruction in a neonate with a large aortopulmonary septal defect.

Aortopulmonary Septal Defect↗
PubMed1992

Effects of light and darkness on pH outside rod photoreceptors in the cat retina.

We recorded pH in the extracellular space surrounding rod photoreceptors in the dark-adapted eye of the cat and during illumination with double-barreled H(+)-selective microelectrodes. A pH of 7.17 was recorded in the vitreous at the retinal surface of the dark-adapted eye and this became more alkaline during light adaptation. In dark adaptation, a pH close to 7.00 was recorded in a region of maximal acidity in the extracellular space surrounding rods in the outer nuclear layer (ONL). pH steeply alkalinized as the microelectrode was moved more distally towards the retinal pigment epithelium (RPE), and almost reached the pH of the arterial blood at the apical surface of the RPE. Illumination produced an intraretinal alkalinization that was largest (up to 0.2 pH units) in the ONL, maximal in amplitude at rod-saturating intensities, and that was sustained during steady background illumination. The light-evoked alkalinization was relatively slow in onset, having a time constant (1/e) of 64 sec, and took 8-12.5 min to return to the dark-adapted level after the offset of maintained illumination. These results show that acid production by cat rods is highest in the dark, reflecting a high rate of energy metabolism, and suggest that glycolysis is required to support the dark current. Illumination, by suppressing both glycolysis and respiration, alkalinizes the extracellular space surrounding rods. The substantial change in pH outside rods from dark to light could alter pH dependent properties of the interphotoreceptor matrix.

Adaptation, Ocular↗