Biomedical subjects

F Yamamoto

Publications and source records attributed to F Yamamoto.

At least 145 records · Page 8Linked to original sources

PubMed1992

[Biventricular repair for right isomerism associated with transposition of great arteries and common atrioventricular canal].

A 5-years old boy, whose thoracic situs was right isomerism, was diagnosed as transposition of great arteries, common atrioventricular canal (intermediate type), severe tricuspid valve regurgitation, pulmonary valve stenosis, bilateral superior vena cava and left sided inferior vena cava. The preoperative RVEDV was 95% and LVEDV 160%, and LV/RV pressure ratio was 0.54. Atrial rerouting using pericardial patch, replacement of tricuspid valve and pulmonary valvotomy were performed. Postoperative course was uneventful. This was a rare case of right isomerism who received biventricular repair.

Child, Preschool↗

PubMed1992

[The effects of osmolarity in reperfusion solution upon myocardial protection].

The effects of several different osmolarity in reperfusion solution were studied. Experimental time course was as follows: 20 min working perfusion, 3 min cardioplegic infusion with St. Thomas Cardioplegic Solution (STS) followed by global ischemia for 33 min at 37.5 degrees C, 15 min early Langendorff reperfusion with different osmolarity by adding sucrose and 5 min late reperfusion with Krebs Henseleit bicarbonate buffer, followed by 20 min working perfusion. Percent recoveries of aortic flow showed that 290 mOsm/L in reperfusion solution possessed optimal protective properties with bell shaped dose response characteristics.

Animals↗

PubMed1992

Continuous monitoring of blood oxygen saturation of internal jugular vein as a useful indicator for selective cerebral perfusion during aortic arch replacement.

We continuously monitored blood oxygen saturation in the internal jugular vein during selective cerebral perfusion for aortic arch operations and evaluated its efficacy as an indicator of cerebral oxygen metabolism. The selective cerebral perfusion method was applied in 11 patients who underwent operations for aortic arch replacement. Blood oxygen saturation in the internal jugular vein was continuously monitored at the bulbus jugularis with a fiberoptic catheter during the operation. Perfusion flow of 500 ml/min was continued for 134.7 +/- 14.9 minutes under moderate hypothermia at 25 degrees C, and bilateral temporal arterial pressure was 40 to 60 mm Hg. Blood gas data were used to estimate oxygen consumption, oxygen extraction ratio, and lactate uptake in the cerebrum. No patients had postoperative cerebral complications. Cerebral oxygen consumption was 2.93 +/- 0.4 ml/min/100 gm under general anesthesia at 36 degrees C. While selective cerebral perfusion at 25 degrees C decreased consumption to 0.92 +/- 0.39 ml/min/100 gm, it fell to about 30% of its former value. Blood oxygen tension in the internal jugular vein showed no significant correlation with rectal temperature. Selective cerebral perfusion did not significantly affect cerebral lactate uptake. In contrast, blood oxygen saturation in the internal jugular vein was significantly affected by temperature and cerebral flow during selective cerebral perfusion, and blood oxygen saturation in the internal jugular vein correlated closely with cerebral oxygen extraction ratio (r = 0.91). Cerebral oxygen metabolism was thus well maintained, and continuous monitoring of blood oxygen saturation in the internal jugular vein was found to serve as a useful indicator under selective cerebral perfusion during operations for aortic arch replacement.

Adult↗

PubMed1991

An endonuclease activity in human polymorphonuclear neutrophils that removes 8-hydroxyguanine residues from DNA+.

An endonuclease that specifically removes 8-hydroxyguanine (oh8Gua) from DNA has been isolated from Escherichia coli. As the amount of oh8Gua produced in DNA of X-ray-irradiated mice is known to decrease with time after irradiation, an attempt was made to find a similar activity in human polymorphonuclear neutrophils (PMNs) using a synthetic dsDNA containing oh8Gua as a substrate. The PMN enzyme was isolated free of other DNases, and found to cleave the substrate DNA simultaneously at 2 sites, the phosphodiester bonds 5' and 3' to oh8Gua, producing free hydroxyl and phosphate groups, respectively. The enzyme showed almost no activity on DNAs containing other kinds of modified base tested or mismatched DNA. Thus human cells also contain an endonuclease that specifically removes oh8Gua residues from DNA.

Base Sequence↗

PubMed1991

Identification in human genomic DNA of the sequence homologous but not identical to either the histo-blood group ABH genes or alpha 1----3 galactosyltransferase pseudogene.

Based on polymerase chain reaction (PCR) and sequencing of the cloned amplified fragments, we identified a homologous sequence to the histo-blood group ABH genes and alpha 1----3 galactosyltransferase pseudogene. The presence of this sequence in human genomic DNA was confirmed by Southern hybridization.

ABO Blood-Group System↗

PubMed1991

The effects of several pharmacologic agents upon postischemic recovery.

Using an isolated working rat heart model, the effects of DL-verapamil, ryanodine, gabexate mesilate (FOY), recombinant human superoxide dismutase (RH-SOD), and coenzyme Q10 upon myocardial protection were evaluated. Under conditions of normothermic ischemia, all these compounds, except RH-SOD, when added to the St. Thomas' cardioplegic solution at an optimal concentration, showed beneficial effects upon functional recovery and enzyme leakage. In contrast, the above compounds, except ryanodine and FOY, failed to improve the protective properties of the St. Thomas' cardioplegic solution under conditions of hypothermic ischemia. Our results indicate that calcium overload via the calcium channel and calcium-induced calcium release from sarcoplasmic reticulum (SR) may contribute to the onset of ischemic-reperfusion injury. However, under conditions of hypothermic ischemia, calcium-induced calcium release from SR plays a dominant role in calcium overload. Furthermore, intracellular calcium overload may activate proteases and result in the acceleration of myocardial injury.

Animals↗

PubMed1991

Medical dissolution of gallstones. Clinical experience of d-limonene as a simple, safe, and effective solvent.

Retained gallstones in the bile ducts account for 60-70% of all the cases of postcholecystectomy syndromes. A solvent d-limonene preparation was injected directly to the biliary system of 200 patients to dissolve or disintegrate the retained gallstones. The outcomes were: retained stones completely disappeared in 96 cases (48%); partial dissolution in 29 (14.5%); chelating agent was also used with partial dissolution in 16 (8%); ineffective in 59 (24.5%). To make this method more effective, several guidelines should be observed including an in vitro trial dissolution test. Cautious observation for possible side effects and frequent hepatic and pancreatic function tests during the treatment with this preparation also should be performed.

Bile Duct Diseases↗

PubMed1991

Harmful effects of inotropic agents on myocardial protection.

Using an isolated working rat heart model, the pretreatment effects of positive inotropic agents on ischemia-reperfusion injury were investigated. The experiment consisted of (1) working control perfusion; (2) working perfusion with isoproterenol (I), milrinone (M), a combination of these drugs (I + M) and dibutyl-cyclic adenosine monophosphate (DB) followed by ischemic arrest for 33 minutes at 37 degrees C or 150 minutes at 20 degrees C and Langendorff reperfusion; and (3) working perfusion. Under conditions of normothermic ischemia, percent recoveries of postischemic cardiac output (mean +/- standard error of the mean) in the I, M, I + M, and DB groups were 37.8% +/- 12.7%, 61.3% +/- 3.1%, 0%, and 53.1% +/- 5.2%, respectively. Under conditions of hypothermic ischemia, the percent recoveries in I + M and DB groups were 10.9% +/- 7.9% and 29.8% +/- 9.5%; they were all significantly lower than that in the control group. The addition of diltiazem or ryanodine at several concentrations and lowering of the Ca2+ concentration in the St. Thomas' cardioplegic solution did not prevent I + M-induced injury. Our data suggest that pretreatment by I + M aggravated ischemia-reperfusion injury, and adjustments in Ca2+ concentration were not sufficient to prevent that injury.

Animals↗

PubMed1991

[The effects of calcium concentration of reperfusion solution upon myocardial protection].

The effects of several calcium concentrations in reperfusion solution were studied. Experimental time course was as followed: 20 min working perfusion, 3 min cardioplegic infusion with St. Thomas cardioplegic solution (STS) followed by global ischemia for 30 min at 37.5 degrees C, 15 min early Langendorff reperfusion with reperfusion solution and 5 min late reperfusion with Krebs Henseleit bicarbonate buffer [( Calcium] = 2.5 mM), followed by 20 min working perfusion. Percent recoveries of aortic flow at the Ca concentration of 0, 0.1, 0.6, 1.2, 1.8, 2.5 mM were 0, 14 +/- 1, 43 +/- 4, 64 +/- 3, 55 +/- 2, 59 +/- 1 (%), respectively. Our data indicated that reperfusion solution with less than 1.2 mM calcium reduced the protective properties of STS.

Animals↗

PubMed1991

[The effects of magnesium concentration in reperfusion solution upon myocardial protection].

Experimental time course was as follows: 20 min working perfusion, 3 min cardioplegic infusion with St Thomas Cardioplegic Solution followed by global ischemia for 35 min at 37.5 degrees C, 15 min first Langendorff reperfusion with reperfusion solution (RS) with various concentrations of Mg and 5 min second reperfusion with KHBB, followed by 20 min working. Cardiac functions were measured during pre and post working perfusion and CK leakage were measured during reperfusion. Percent recoveries of aortic flow at the Mg concentration of 0, 0.6, 1.2, 3.0, 6.0, 12 mM were 21 +/- 5, 22 +/- 3, 48 +/- 2, 37 +/- 4, 28 +/- 3, 15 +/- 3 (%) (mean +/- SEM), respectively. Our data indicated that 1.2 mM Mg of RS possessed protective properties with bell shaped dose response characteristics.

Animals↗

PubMed1991

[Modified Fontan operation for a single ventricle with a nonconfluent pulmonary artery].

A 8-year-old boy with a double inlet right ventricle with a non-confluent pulmonary artery was operated on with a modified Fontan operation. He had right isomerism, right aortic arch, bilateral superior caval veins, and left-sided inferior caval vein. Hepatic veins were separately drained to the right-side atrium. Left Blalock-Taussig shunt and right central shunt operations had been previously performed. Firstly, we had reconstructed the central pulmonary artery with a 16 mm porcine pericardial roll to unify the nonconfluent pulmonary arteries. Secondly, about 2 months after the first operation, we performed a modified Fontan operation. Systemic venous return from the inferior caval vein and the hepatic veins were drained to a reconstructed pericardial roll with an intraatrial Gore-Tex graft, and bilateral superior caval veins were also anastomosed to the roll. The structure of the pulmonary arterial system is one of the most important factors to determine the outcome of a modified Fontan operation. Even if the central pulmonary artery is absent, however, a modified Fontan operation is applicable for the patient whose peripheral pulmonary arteries have enough growth.

Blood Vessel Prosthesis↗

PubMed1991

[Ventricular septation combined with arterial switch for a patient with double inlet left ventricle with right sided rudimentary right ventricle and ventriculoarterial discordance].

A 5-year-old boy with double inlet left ventricle and ventriculoarterial discordance (SDD type) underwent ventricular septation with arterial switch procedure. Previously he had received pulmonary arterial banding at 3 months-old. Preoperative cardiac catheterization revealed Qp/Qs 1.26, Pp/Ps 0.19 and LVEDV was 315% of normal (as left ventricle). Arterial switch with Lecompte modification was performed in order to separate ventricle with straight patch could be done. Post operative course was uneventful and patient was extubated 4 post operative day. These procedures had employed in this patient as follows; 1) systemic ventricle could be constructed with morphological left ventricle with mitral valve. 2) left ventricular outflow tract stenosis due to ventricular outlet foramen occasionally observed in conventional procedure such as intraventricular rerouting could be prevented, and 3) ventricular septation could be easy and simple with straight patch.

Aorta↗

PubMed1991

[Effects of nitroglycerin upon myocardial metabolism after open heart surgery].

The effects of intravenous administration of nitroglycerin (TNG) on hemodynamics and myocardial metabolism after open heart surgery were evaluated in 22 patients without ischemic heart disease. On 12 hours after starting the continuous infusion of TNG at a rate of 0.2 micrograms/kg/min on 10 patients (TNG group), coronary blood flow (CBF) increased (p less than 0.01) and myocardial oxygen metabolism improved remarkably. However, anaerobic metabolism still existed in TNG group and no significant difference between TNG group and Control group even after 12 hour continuous drug infusion. From these studies, it was concluded that the intravenous administration of TNG at a rate of 0.2 microgram/kg/min increased CBF, however did not improve myocardial metabolism after open heart surgery possively probably because of changes in coronary collateral function.

Adult↗

PubMed1991

[Entirely suprasellar symptomatic Rathke's cleft cyst].

Two rare cases of entirely suprasellar Rathke's cleft cyst were reported. Case 1. A 62-year-old man was admitted to our hospital on the 14th of January, 1988, complaining of headache and diplopia. A plain skull x-ray showed the sella turcica was normal. CT scan and MRI demonstrated a lesion mass located entirely in the suprasellar cistern. Right frontotemporal craniotomy was performed, and the cyst wall was resected subtotally. Microscopic sections of cyst wall showed ciliated single layer with focal stratified epithelium. Case 2. A 51-year-old man was hospitalized complaining of visual impairment in the left eye. Endocrinological examination showed no abnormalities. CT and MRI demonstrated a lesion mass located entirely in the suprasellar region. Right frontotemporal craniotomy was performed. The mass was opened and a large amount of yellowish fluid was released. Histologically, the specimens were simple ciliated cuboidal epithelium. Postoperative courses of these patients were uneventful. The findings on CT and MRI of the cases located entirely in the suprasellar region were varied. The histopathogenesis and embryological pathogenesis of Rathke's cleft cyst in the literature, particularly the entirely suprasellar type, were discussed.

Craniopharyngioma↗

PubMed1990

Sugar-nucleotide donor specificity of histo-blood group A and B transferases is based on amino acid substitutions.

Four amino acid substitutions (aa 176, 235, 266, and 268) have been found between the coding regions of cDNAs for histo-blood group A and B transferases (Yamamoto F., Clausen, H., White, T., Marken, J., and Hakomori, S. (1990) Nature 345, 229-233). Here we establish the basis of differential affinity of these glycosyltransferases to nucleotide-sugar (UDP-GalNAc or UDP-Gal). On the basis of gene reconstruction experiments and studies of expression in DNA transfected HeLa cells, the third as well as the fourth aa substitutions (leucine and glycine in A and methionine and alanine in B), which were calculated to modify flexibility of the protein, were found to be crucial in determining nucleotide-sugar specificity. The second substitution (glycine in A and serine in B) also affects the specificity. We have also created new enzymes which catalyze the transfer of both GalNAc and Gal, and may provide an explanation of the rare cis-AB phenotype.

ABO Blood-Group System↗

PubMed1990

Molecular genetic basis of the histo-blood group ABO system.

The histo-blood group ABO, the major human alloantigen system, involves three carbohydrate antigens (ABH). A, B and AB individuals express glycosyltransferase activities converting the H antigen into A or B antigens, whereas O(H) individuals lack such activity. Here we present a molecular basis for the ABO genotypes. The A and B genes differ in a few single-base substitutions, changing four amino-acid residues that may cause differences in A and B transferase specificity. A critical single-base deletion was found in the O gene, which results in an entirely different, inactive protein incapable of modifying the H antigen.

ABO Blood-Group System↗

PubMed1990

Characterization through cDNA cloning of galactoprotein b3 (Gap b3), a cell surface membrane glycoprotein showing enhanced expression on oncogenic transformation. Identification of Gap b3 as a member of the integrin superfamily.

Galactoprotein b (Gap b) is a group of glycoproteins of fibroblast cell membranes showing enhanced expression in association with oncogenic transformation (Carter, W.G., and Hakomori, S. (1977) Biochem. Biophys. Res. Commun. 76, 299-308). We purified Gap b3 (one of the Gap b group) to homogeneity from hamster fibroblast NIL cells transformed with polyoma virus (NILpy). Partial amino acid sequence was determined, and the cDNA clones encoding this protein were isolated by oligodeoxynucleotide hybridization. The 5.0-kilobase pair cDNA encodes a protein of 1051 amino acid residues containing a signal peptide (32 residues), a large extracellular domain (959 residues), a transmembrane domain (28 residues), and a short cytoplasmic domain (32 residues). The overall structure of Gap b3 is similar to that of the alpha subunit of so-called integrin receptors in the following respects: (i) presence of metal-binding sequences; (ii) location of a transmembrane domain near C terminus; (iii) matched positions of most of the cysteine residues. This, together with extensive amino acid sequence homology, strongly suggests that Gap b3 is a member of the integrin family. Gap b3 consists of two polypeptide chains (Mr = 110,000 and 30,000), which seem to be proteolytic cleavage products connected by disulfide bonds from a precursor protein. Southern hybridization shows the presence of a single copy gene in mice and humans as well. Northern hybridization analysis shows that the enhanced expression of Gap b3 in transformed cells is due to increased transcription of its message.

Amino Acid Sequence↗

PubMed1990

Cloning and characterization of DNA complementary to human UDP-GalNAc: Fuc alpha 1----2Gal alpha 1----3GalNAc transferase (histo-blood group A transferase) mRNA.

Based on the partial amino acid sequence, the cDNA encoding UDP-GalNAc:Fuc alpha 1----2Gal alpha 1----3GalNAc transferase, the specific primary gene product of histo-blood group A gene (A transferase), was cloned and sequenced. Poly(A)+ RNA from human stomach cancer cell line MKN45, expressing high levels of A antigen, was used for construction of a lambda gt10 cDNA library. Degenerate synthetic oligodeoxynucleotides were used for polymerase chain reactions to detect the presence of the sequence of interest in cDNA (presence test) and to identify the correct clones (identification test) after screening the library with a radiolabeled polymerase chain reaction amplified fragment. Nucleotide sequence analysis revealed a coding region of 1062 base pairs encoding a protein of 41 kDa. Hydrophobicity plot analysis shows the existence of three domains: N-terminal short stretch, transmembranous hydrophobic region, and a long C-terminal domain (a feature common to all glycosyltransferases cloned so far). Southern hybridization analysis has shown that this DNA does not represent a multigene family. No restriction fragment length polymorphism was found to correlate with ABO blood group type. Bands were detected in Northern hybridization of mRNAs from cell lines expressing A, B, AB, or H antigens. These results suggest that sequences of ABO genes are essentially very similar (with minimal differences), and the inability of the O gene to encode A or B transferases is probably due to structural differences rather than A or B transferase expression failure.

Amino Acid Sequence↗