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Biomedical subjects

T Horiuchi

Publications and source records attributed to T Horiuchi.

At least 379 records · Page 21Linked to original sources
PubMed1989

Regulation of aldosterone biosynthesis by Na+/H+ antiport: relationships between intracellular pH and angiotensin II.

Recent studies on the regulation of aldosterone biosynthesis have revealed that inhibitors of sodium influx, e.g. amiloride, can inhibit adrenal steroidogenesis with a pharmacological profile suggestive of a Na+/H+ antiport system. We have examined the existence of a Na+/H+ antiport system and its regulation of Na influx and intracellular pH (pHi) in bovine adrenal zona glomerulosa cells. NH4Cl-induced 22Na uptake by zona glomerulosa cells was dose dependently inhibited by ethylisopropylamiloride (EIPA), amiloride, and benzamil with ED50 values of 0.02, 4.30, and 199 microM, respectively. Angiotensin II (AII; 100 nM) caused an initial transient acidification, followed by prolonged alkalinization. The hormone equipotently increased pHi and stimulated aldosterone secretion, with ED50 values of 1.2 and 1.4 nM, respectively. AII-induced alkalinization was suppressed by EIPA, amiloride, and benzamil, with ED50 values of 0.6, 79, and 440 microM, respectively. This increase in pHi induced by AII was dependent upon the extracellular sodium concentration (ED50 values = 2.8 mM) and was blunted in sodium-free medium. AII-stimulated aldosterone synthesis was also inhibited by EIPA, amiloride, and benzamil, with ED50 values of 0.07, 34, and 330 microM, respectively. The time course of activation by angiotensin II on aldosterone secretion was also dependent upon extracellular sodium concentration during a 2-h period. These results document that intracellular pH is regulated through the Na+/H+ exchange system and suggest that the pH change induced by AII might be associated with its regulation of steroidogenesis in bovine adrenal zona glomerulosa cells.

Aldosterone↗
PubMed1989

Assessment of clinical application of test-dose concept for theophylline in patients with respiratory failure.

The possibility of clinical application of test-dose concept for theophylline was assessed in 11 patients with serious underlying disease who required theophylline. Based on the pharmacokinetic parameters calculated from the single intravenous aminophylline administration, they received a continuous infusion of aminophylline in order to maintain about 10 micrograms/ml plasma which is considered to be the lowest therapeutic level. Plasma levels during a constant rate infusion were assayed at 6:00, noon, 18:00 and midnight on the 3rd or 4th day after the infusion had started. There were no significant differences among plasma levels at each sampling time, but plasma levels varied ranging from 5.1 to 24.8 micrograms/ml (12.1 +/- 5.5 micrograms/ml: mean +/- S.D.), which values were in disagreement with the predicted value in some cases. The correlations of the theophylline clearance ratio to dose, pH, arterial partial pressures of oxygen (Pao2) and carbon dioxide (Paco2) ratios, which were calculated by dividing the value during continuous infusion by the value at the test dose, were investigated to evaluate which factor largely contributed to the failure of this dosing method. Although the clearance ratio did not correlate to pH and Pao2 ratios, significant negative relationships were observed between the clearance ratio and the dose (p less than 0.05) or Paco2 ratios (p less than 0.02). In other words, the alternation of dose or Paco2 resulted in the change of theophylline clearance. These findings suggest that the test-dose concept should not be used in the seriously ill patients whose theophylline clearance can change easily in relation to dose and/or Paco2 change.

Aged↗
PubMed1989

A successful delivery of an extremely immature infant in Rh incompatibility after plasma exchange.

When Rh incompatible pregnancies occur, intrauterine fetal transfusion (IUT) and plasma exchange (PE) have made it possible to prolong the prenatal duration and to dramatically decrease the neonatal mortality. We administered a total of 10 PEs (from 20 weeks to 27 weeks of gestation) and one IUT (at 27 weeks and 1 day) for an Rh-isoimmunized gravida who already had a high maternal serum Rh antibody titer at the 14th gestational week, and delivered by Caesarian section (CS) an extremely immature infant of only 873 grams at 27 weeks and 4 days of gestation. The infant was hydropic with hyperbilirubinemia, therefore exchange transfusions were administered immediately after birth. The infant's weight reached the lowest point of 669 grams on the 13th day after birth, but began to increase thereafter. The baby weighted 3,052 grams on the 144th day and left the hospital without any complications.

Blood Transfusion, Intrauterine↗
PubMed1989

[Experimental study of materials used for intra-atrial baffle for the Mustard operation].

An experimental model was developed to study the fate of prosthetic materials used for the construction of an intra-atrial baffle for the Mustard operation. Total atrial septa were replaced in sixteen puppies with autologous pericardium (n = 3), glutaraldehyde-preserved canine pericardium (n = 4), glutaraldehyde-preserved porcine pericardium (n = 3), EPTFE reinforced sheet (Gore-Tex sheet, n = 3) and EPTFE reinforced cardiovascular patch (Gore-Tex patch, n = 3). Septal replacement was performed under total circulatory arrest and surface induced deep hypothermia. All animals were sacrificed six months after the septal replacement. Pathological examination revealed that all septal grafts were well healed, completely covered by neoendothelium and had contracted to approximately 60% of their original size. There were no significant difference between groups. Histologic examination showed the good tissue adaptation of autologous pericardium and Gore-Tex patch materials. The thinnest layers of neoendothelium covered autologous pericardial baffle. Glutaraldehyde-preserved pericardium and Gore-Tex sheet did not adapt well to host atrial tissue. These materials were easily detached from their neoendothelial substrates. It was concluded that the autologous pericardium as well as a Gore-Tex patch may be superior to other prosthetic materials used for the construction of an intra-atrial baffle for the correction of transposition of the great arteries.

Animals↗
PubMed1989

[Emergent surgical management of aortic dissecting aneurysm, type A Stanford, complicated with acute cardiac tamponade; report of a case].

A 52-year-old woman, who had been treated medically for 31 days with the diagnosis of type A aortic dissection, suddenly fell in shock because of acute cardiac tamponade. Emergent operation was performed two hours after the onset of shock. Entry and perforation were located in the ascending aorta. Ascending aorta was opened without cross-clamping under profound hypothermic low flow perfusion through femoral artery, and intraluminal grafting with a double ringed graft was completed. Combined technique of open distal anastomosis and ringed graft is useful in such an emergent case as cardiac tamponade of aortic dissection.

Aortic Dissection↗
PubMed1989

Protein binding characteristics of a new bronchodilator, 1-methyl-3-propylxanthine (MPX), in different species.

The protein binding of a new bronchodilator, 1-methyl-3-propylxanthine (MPX), in different animal species sera (human, dog, rabbit, rat and mouse) was investigated in vitro by ultrafiltration method. Interspecies differences in the binding affinity and binding capacity for MPX were observed. The dissociation constant (Kd1) for the high affinity binding site of human serum was approximately 17 times higher than that of rat serum. Those of rat serum and rabbit serum were nearly equal. On the other hand, the binding indices (n1p1/kd1) of human serum and rat serum were comparable. The binding of MPX to various proteins such as human serum albumin (HSA), alpha 1-acid glycoprotein (AGP) and isolated human lipoproteins was also investigated. The binding of MPX to HSA was lower than that of human serum protein but the number of specific binding sites (n1) in human serum was in agreement with that in HSA. The binding curves of MPX to AGP and lipoproteins were almost linear and the binding percentages were less than 7% in both cases. These data suggest that MPX is exclusively bound to albumin and that AGP and lipoproteins are of little importance in the protein binding of MPX. The present data appear to be useful for predicting the role of protein binding on the pharmacokinetics of MPX in different animal species.

Animals↗
PubMed1989

[Clinical experience for ventricular assist device].

We began applying of our VAD system clinically in 1982 and have subsequently obtained good results. The first case treated with the VAD returned to normal life. In a total of 70 cases of clinical applications this system there has been instance of apparatus dysfunction. Confirming the reliability and safety promised by the results of biological experiments. Here, we report the results of clinical application of the system in a total of 61 cases between August, 1985 and March, 1989. The following conclusions were reached: 1) Satisfactory weaning and survival rates were obtained i.e. 18 cases out of 61 cases (30%) survived over one month and 13 cases (21%) are currently surviving, even in elderly patients of 60 years of age or older. 2) The weaning rate and survival rates were good after approximately 1 week of support. Detailed evaluation of the recovery of the heart and functions of other major organs has led to the conclusion that the results can be improved further when the weaning period is carefully determined. 3) With regard to surgical factors, good findings were obtained when the artificial heart-lung bypass time was less than 6 hours. The VAD can be used in the early stages without vainly attempting weaning from the artificial heart-lung bypass. 4) There were no mechanical problems with the hardware of the blood pump drive assembly, etc., or noteworthy side effects.

Aged↗
PubMed1988

A consensus sequence of three DNA replication terminus sites on the E. coli chromosome is highly homologous to the terR sites of the R6K plasmid.

Using the "Ter assay" we developed, three separate replication terminus (terC1, terC2, and terC3) sites on the E. coli chromosome were identified. The locations are at 28.3, 35.6, and 33.9 min on the linkage map, respectively. The terC1 site can block the counter-clockwise replication fork only, while the terC2 and terC3 sites inhibit the clockwise fork traveling on the chromosome. DNA sequences of the terC sites required for termination of DNA replication are highly homologous to those of terminus (terR) sites of the R6K plasmid, and the 21 bp consensus DNA sequence of terC is 5'-(A or T) TTAGTTACAACAT (A or C) CT (A or T) (A or T) (A or T) T-3'. In addition, all Ter active pUC-terC plasmids had a low copy number and were unstable in the host cells.

Base Sequence↗
PubMed1988

Core sequence of two separable terminus sites of the R6K plasmid that exhibit polar inhibition of replication is a 20 bp inverted repeat.

The DNA replication terminus (terR) of the R6K plasmid located on a 216 bp Alul fragment (Alu216) can block progress of the DNA replication fork. We previously developed an electrophoresis assay that allows detection of terminus activity on any DNA fragment cloned in the pUC vector. For precise identification of terR, we tested Alu216, its subfragments, and synthetic oligonucleotides by this assay. We found terR to be composed of a pair of separable sites, terR1 and terR2, each of which can block the DNA replication fork traveling in a specific but not the opposite direction. Both terR sites were composed of 22 nucleotides containing the repeated 20 bp sequence 5'-TAGTTACAACAC(A or T) CAA(G or T) AGA-3', located 73 bp apart in the inverted position of Alu216. A DNA homology search suggested that the R6K plasmid and the E. coli chromosome share a common termination system.

Base Sequence↗
PubMed1988

Control of cell division by sex factor F in Escherichia coli. III. Participation of the groES (mopB) gene of the host bacteria.

Cell division of F+ bacteria is coupled to DNA replication of the F plasmid. Two plasmid coded genes, letA (ccdA) and letD (ccdB) are indispensable for this coupling. To investigate bacterial genes that participate in this coupling, we attempted to identify the target of the division inhibitor (the letD gene product) of the F plasmid. Two temperature-sensitive growth defective mutants were screened from bacterial mutants that escaped the letD product growth inhibition that occurs in hosts carrying an FletA mutant. Phage P1-mediated transduction and complementation analysis indicated that the temperature-sensitive mutations are located in the groES (mopB) gene, which is essential for the morphogenesis of several bacteriophages and also for growth of the bacteria. The nucleotide sequence of the promoter region of the gene in which the temperature-sensitive mutations had occurred was virtually identical with that of the groES gene of Escherichia coli; furthermore the sequence of the first five amino acid residues and the overall amino acid composition predicted from the nucleotide sequence of the gene match those of the purified GroES protein. The temperature-sensitive mutants did not allow the propagation of phage lambda at 28 degrees C and formed long filamentous structures without septa at 41 degrees C, as is observed in the case of groES mutants. Growth of the two groES mutants tested was not inhibited by the F plasmid with the letA mutation. These observations suggest to us that the morphogenesis gene groES plays a key role in coupling between replication of the F plasmid and cell division of the host cells.

Bacterial Proteins↗
PubMed1988

Production of monoclonal antibody to characterize the antigen of Paragonimus westermani.

We produced monoclonal antibodies against the adult antigen of Paragonimus westermani to investigate the expression of the stage-specific antigen of adult flukes. Two hybridoma cell lines, A1-2 and A4-1, were established. A1-2 reacted specifically only with the adult antigen in an enzyme-linked immunosorbent assay (ELISA), whereas A4-1 reacted with both adult and larval antigens. By immunoblotting analysis, A1-2 was found to react with four bands with molecular weights of 35,000, 17,000, 15,500, and 12,500 in the adult antigen but with none in the larval antigen. A4-1 was found to bind to the band of 27,000 daltons in the adult antigen as well as those of 28,000 and 26,000 daltons in the larval antigen. By immunohistochemical methods, a positive reaction was observed only in the parenchymal tissues of the adult flukes with A1-2. A4-1 reacted with the substance that located on the gut epithelium and in the luminal contents of both the adult and larval flukes. These results indicate that the adult P. westermani possesses an antigen or antigenic determinant specific to the adult stage, as well as that common to both the larval and adult stages.

Animals↗
PubMed1988

Effect of subcutaneous injection of a long-acting analogue of somatostatin (SMS 201-995) on plasma thyroid-stimulating hormone in normal human subjects.

SMS 201-995 (SMS), a synthetic analogue of somatostatin (SRIF) has been shown to be effective in the treatment of the hypersecretion of hormones such as in acromegaly. However, little is known about the effects of SMS on the secretion of thyroid-stimulating hormone (TSH) in normal subjects. In this study, plasma TSH was determined with a highly sensitive immunoradiometric assay, in addition to the concentration of SMS in plasma and urine with a radioimmunoassay, following subcutaneous injection of 25, 50, 100 micrograms of SMS (4 subjects/dose) or a placebo (6 subjects) to normal male subjects, at 0900 h after an overnight fast. The plasma concentrations of SMS were dose-responsive and the peak levels were 1.61 +/- 0.09, 4.91 +/- 0.30 and 8.52 +/- 1.18 ng/ml, which were observed at 30, 15 and 45 min after the injection of 25, 50 and 100 micrograms of SMS, respectively. Mean plasma disappearance half-time of SMS was estimated to be 110 +/- 3 min. Plasma TSH was suppressed in a dose dependent manner and the suppression lasted for at least 8 hours. At 8 hours after the injection of 25, 50 and 100 micrograms of SMS, the plasma TSH levels were 43.8 +/- 19.4, 33.9 +/- 9.4 and 24.9 +/- 3.2%, respectively, of the basal values. The results suggest that SMS suppresses secretion of TSH from the normal thyrotrophs in man and thus also that attention should be paid to possible hypothyroidism during the long-term treatment of patients such as those with acromegaly with this potent analogue of SRIF.

Adult↗
PubMed1988

Double-outlet left atrium with intact ventricular septum.

The clinical course and surgical repair of double-outlet left atrium with intact ventricular septum in a 13-year-old girl are presented. The only outlet of the right atrium was a secundum atrial septal defect, and the left atrium drained into both ventricles through two atrioventricular valves. To our knowledge, there has been only one other published report of repair of double-outlet left atrium.

Echocardiography↗
PubMed1988

Purification and properties of N-acyl-D-mannosamine dehydrogenase from Flavobacterium sp. 141-8.

A new enzyme, N-acyl-D-mannosamine dehydrogenase, was purified to apparent homogeneity from a cell-free extract of Flavobacterium sp. 141-8 and some of its properties were investigated. The enzyme showed optimum activity at pH 8.0-9.5. N-Acetyl- and N-glycolyl-D-mannosamine were oxidized but other commonly existing sugars, such as N-acetylglucosamine, N-acetylgalactosamine, amino sugars, neutral hexoses, and pentoses, were not oxidized. NAD+ was specifically utilized as an effective hydrogen acceptor. The apparent Km values for N-acetyl- and N-glycolyl-D-mannosamine, and NAD+ were 1.0, 13.3, and 0.41 mM, respectively. The stoichiometry data showed that 1 mol each of N-acetyl-D-mannosamine and NAD+ were converted to 1 mol each of N-acetyl-D-mannosaminic acid and NADH, respectively. Although the formation of lactone was detected in the enzyme reaction mixture, the reverse reaction of the enzyme, the reduction of N-acetyl-D-mannosamino-lactone, was not observed. The enzyme activity was strongly inhibited by Hg2+ and SDS, but metal-chelating reagents and sulfhydryl-group-blocking reagents had almost no effect. The molecular weight of the enzyme was estimated to be 120,000 on gel filtration and 29,000 on SDS-polyacrylamide gel electrophoresis. Its isoelectric point was at pH 4.8. On trial application of the enzyme, it was indicated that N-acetylneuraminic acid can be determined quantitatively with the combined enzyme system involving the new enzyme and N-acetylneuraminic acid aldolase.

Bacterial Proteins↗