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Biomedical subjects

A Sakai

Publications and source records attributed to A Sakai.

At least 271 records · Page 15Linked to original sources
PubMed1991

Detection of patients at risk for paroxysmal atrial fibrillation during sinus rhythm by P wave-triggered signal-averaged electrocardiogram.

To determine whether patients at risk for paroxysmal atrial fibrillation could be detected while in sinus rhythm, the signal-averaged electrocardiogram triggered by P waves was recorded in 42 patients with paroxysmal atrial fibrillation (Paf group) and in 50 control patients. The root mean square voltages (LP10, LP20, and LP30) for the last 10, 20, and 30 msec and the duration (Ad) of filtered (40-300 Hz) P wave of the spatial magnitude were measured. LP10 and LP20 were significantly lower in the Paf than in the control group (LP10, 1.92 +/- 0.58 versus 2.49 +/- 0.78 microV, p less than 0.001; LP20, 2.47 +/- 0.78 versus 3.46 +/- 1.20 microV, p less than 0.0001), although no significant difference in LP30 was found between groups. Ad was also significantly longer in the Paf than in the control group (137.0 +/- 14.3 versus 118.6 +/- 11.3 msec, p less than 0.001). These differences between the Paf and control groups remained significant even after dividing by the presence or absence of organic heart diseases. The criteria of "LP20 = 3.5 microV or less" and "Ad greater than 120 msec" as defining "atrial late potential" gave a sensitivity of 91% and a specificity of 76%. These findings suggest that patients at risk for paroxysmal atrial fibrillation could be detected while in sinus rhythm by using the P wave-triggered signal-averaged electrocardiogram.

Algorithms↗
PubMed1991

Steroidogenic activity of synthetic hybrid molecules composed of human chorionic gonadotropin and either the A or B chain of lectin ricin or horseradish peroxidase.

Human chorionic gonadotropin (hCG) is a glycoprotein consisting of noncovalently bound alpha- and beta-subunits which shows hormonal activity (stimulatory effect on testosterone production) toward rat Leydig cells. To modify the hormonal activity of hCG, hybrid molecules composed of hCG and other glycoproteins, either the A or B chain of lectin ricin (hCG-A and hCG-B) through disulfide bridges and horseradish peroxidase (hCG-HRP) through Schiff's base, were synthesized. Hormonal activity and the effect of these hybrids on [125I]hCG binding to rat Leydig cells were compared to those of native hCG. Modification of hCG resulted in a significant decrease in hormonal activity for hCG-HRP but not for hCG-A to approximately 1/100 and 1/10 that of native hCG, respectively. On the other hand, hCG-B unexpectedly showed hormonal activity similar to that of native hCG. These hybrids inhibited the binding of 125I-labeled hCG to rat Leydig cells with potencies of 1/10, 1/100 and 1/500 that of hCG for hCG-B, hCG-A and hCG-HRP, respectively. These results indicate that the B chain of ricin, the active component hCG-B, participated in stimulating testosterone production according to its own nature. Data which indicate that hybrids consisting of hCG subunits and the B chain of ricin (alpha-B and beta-B) stimulated testosterone significantly more than hybrids consisting of hCG subunits and A chain (alpha-A and beta-A) support the above finding.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

[A surgical experience of aortoventriculoplasty (Konno's procedure) for aortic stenosis associated with hypoplasia of aortic valve ring progressed after the repair of supravalvular aortic stenosis].

A 14-year-old boy with aortic stenosis associated with hypoplasia of aortic valve ring underwent aortoventriculoplasty (Konno's procedure) successfully nine years after the repair of supravalvular aortic stenosis. His aortic annulus diameter before enlargement was 17 to 18 mm and after the procedure, a 25 mm St. Jude Medical prosthetic valve was implanted. It was adequate size for this large-sized student (173 cm in height, 67 kg in weight). After this operation, mild stenosis of right ventricular outflow tract was presented probably due to insufficient reconstruction of right ventricular outflow for such a dramatic enlargement of aortic annulus. Although this procedure makes possible to implant more than three-size larger prosthetic valve without major complications, we have to be careful about preventing right ventricular outflow tract stenosis in case of requiring enlargement over 40 or 50% of aortic annular circle.

Adolescent↗
PubMed1991

[Clinical features of hypernatremic hyperosmolar delirium following open heart surgery].

Five cases of hypernatremic hyperosmolar delirium after open heart surgery were reviewed. Minimum serum osmolarity at the time of developing delirium in these cases was 336 mOsm/l. Blood glucose level did not reached to the levels of the typical criteria of hyperosmolar hyperglycemic nonketotic diabetic coma in all cases. The authors have shown that it was difficult to recognize this unique disorder in early postoperative stage. Because of its non-specific symptoms and the postoperative courses which required the patients' cares with much more dry side in water balance. In order to treat the patients with hypernatremic hyperosmolar delirium, the correction of serum osmolarity should be done very slowly, because water intoxication should be prevented. In all five cases in this paper were recovered from delirium as the time when serum natrium level and serum osmolarity were restored to the normal state. We concluded that in order to get a good prognosis of this characteristic disorder, we have shown early recognition of serum hypernatremia and hyperosmolarity state and consequently adequate treatment mentioned above are primarily important.

Adult↗
PubMed1991

[Maternal immune responses induced by the immunotherapy in patients with recurrent spontaneous abortions].

The mechanism of the beneficial effect of immunotherapy for human reproductive wastage remains to be elucidated. The induction of blocking antibodies such as anti-HLA class II antibodies and anti-idiotypic antibodies was investigated as the mechanism of specific immunosuppression in pregnancy. We reported that changes in a mixed lymphocyte culture (MLC), T-cell subsets and generation of anti-idiotypic antibodies after immunotherapy compared to before. MLC was significantly (p less than 0.001) inhibited after the immunization. The mean inhibition rate was 50.5%, suggesting that MLR blocking antibodies were induced by immunotherapy. We demonstrated that this blocking effect was specific to the husband, because the inhibition of one-way MLC reactions which were set up with responding maternal lymphocytes and MMC-treated stimulating lymphocytes of third parties were significantly low (p less than 0.05) compared to stimulation with paternal lymphocytes. The binding of autoantibodies to alloactivated maternal lymphoblasts against the paternal lymphocytes was detected in post-immunization cases in two-color flow-cytometric experiments. This strongly suggests that anti-idiotypic antibodies were induced by the immunotherapy. The percentage of cytotoxic T cells was significantly decreased (p less than 0.05) and the percentage of suppressor T cells was significantly increased (p less than 0.01) after the immunotherapy, suggesting that a cell-mediated immune response was induced by the immunotherapy.

Abortion, Habitual↗
PubMed1990

Effects of quercetin, a plant flavonol, on the two-stage transformation in vitro.

Quercetin was examined for the effects on the two-stage chemical transformation of BALB/3T3 cells. Quercetin showed initiating action to induce transformation in the cells which were treated with quercetin and subsequently with 0.49 microM 12-O-tetradecanoyl-phorbol-13-acetate (TPA). Both the proportion of dishes with transformed foci and the average number of foci per dish increased with the concentration of quercetin (15-45 microM). However, initiating treatment with quercetin did not induce transformation without subsequent TPA treatment. Quercetin inhibited the promotion caused by 0.49 microM TPA in the transformation initiated by 1.9 microM 2-methylcholanthrene (MCA). The inhibitory effect of 30 microM quercetin was 56% in the number of foci per dish. Thus quercetin was found to have initiating effect on the transformation of BALB/3T3 cells, but to restrain the promotion by TPA.

Animals↗
PubMed1990

Integration of heterologous genes into the chromosome of Saccharomyces cerevisiae using a delta sequence of yeast retrotransposon Ty.

Distribution of a delta (delta) sequence of the Ty element on a chromosome of the yeast Saccharomyces cerevisiae was analysed by pulsed-field gel electrophoresis. More than 100 copies of the delta sequence were nonrandomly distributed on the chromosome. Using the delta sequence as a recombination site, mouse alpha-amylase and human beta-endorphin genes were introduced into the chromosomal DNA. The integration occurred on a particular chromosome in each case and the copy number was estimated as three to five. It was also found that single- or multi-copy integration occurred at a single or multiple sites on the particular chromosome. The integrants secreted alpha-amylase and beta-endorphin by three-to fivefold compared with single-copy integrants. This type of integration was mitotically stable over a period of 50 generations under non-selective conditions.

Chromosomes↗
PubMed1990

Effect of cyclic guanosine monophosphate on hypoxic and angiotensin-II-induced pulmonary vasoconstriction.

We examined, in isolated blood perfused rat lungs, the effect of the cell permeable 8-bromo derivative of cGMP on pulmonary vasoconstriction induced by either alveolar hypoxia or angiotensin II. 8-Bromo cGMP dose-dependently reduced both hypoxia-(IC50 = 2.2 X 10(-5) M) and angiotensin-II-induced pulmonary vasoconstriction (IC50 = 5.0 X 10(-5) M). This effect of 8-bromo cGMP on pulmonary vasoconstriction was not affected by cyclooxygenase blockade. M & B 22948 (0.1 mM), an inhibitor of cGMP-phosphodiesterase, reduced synergistically with 8-bromo cGMP the hypoxia or angiotensin-II-induced vasoconstriction. The cGMP-phosphodiesterase inhibitor M & B 22948, by itself, selectively reduced hypoxia-induced vasoconstriction, suggesting a modulating effect of endogenous cGMP during hypoxic vasoconstriction.

3',5'-Cyclic-GMP Phosphodiesterases↗
PubMed1990

Cytoprotective effect of TRK-100, a prostacyclin analogue, against chemical injuries in cultured human vascular endothelial cells.

We studied the cytoprotective effect of TRK-100, a chemically stable analogue of prostacyclin (PGI2), in the cultured human endothelial cells from umbilical vein. TRK-100 (10 and 100 nM) stimulated significantly proliferation of endothelial cells but did not affect PGI2 production in endothelial cells. Exposure of cultured endothelial cells to homocysteine (2.5 mM) or glucose (50 mM) caused concentration-dependent cytotoxicity, as evidenced by a decrease in number of viable cells. When endothelial cells were treated with TRK-100 simultaneously or prior to, but not after, exposure to injury substances, decreases in viable cell were significantly suppressed. The protective effect of TRK-100 against homocysteine-induced cytotoxicity also appeared in endothelial cells treated with acetylsalicylic acid, suggesting that endogenous PGI2 did not involve in the protective effect of TRK-100.

Cell Division↗
PubMed1990

Comparison of standard (non-oxygenated) vs. oxygenated St. Thomas' Hospital cardioplegic solution No. 2 (Plegisol).

Recent studies have suggested that oxygenation of crystalloid cardioplegic solutions improves myocardial preservation. To assess whether oxygenation of St. Thomas' Hospital cardioplegic solution No. 2 (Plegisol) improves its clinical efficacy, 50 patients were randomly assigned into 2 groups: (1) those receiving Plegisol and (2) those receiving O2-Plegisol (PO2 greater than 500 mmHg at 4 degrees C). Efficacy was assessed by (a) clinical and haemodynamic parameters, (b) quantitative birefringence changes in response to ATP and calcium as a measurement of myocardial preservation in left and right ventricular biopsies, (c) creatine kinase (MB isoenzyme) release for up to 4 days postoperatively, (d) electrocardiographic (ECG) monitoring for up to 7 days postoperatively. There were no differences in mean age, ejection fraction, aortic cross-clamp duration, or bypass duration between the 2 groups of patients. In the Plegisol group, 2 patients (8%) died and 4 patients (16%) required inotropic support, whereas in the O2-Plegisol group there were no deaths and only 2 patients (8%) required inotropic support. These differences, however, were not statistically significant. Birefringence assessment demonstrated an improved myocardial response to ATP and calcium (predominantly in the left ventricular epimyocardium and in the right ventricular biopsies) at the end of ischaemia and after reperfusion in patients given O2-Plegisol. Deterioration in cellular assessment of myocardial contractility (measured by a reduction in birefringence of greater than 0.4 nm) was reduced from 20% in Plegisol patients to 12.5% in O2-Plegisol patients. CK-MB values showed no difference at any sampling time between the 2 groups of patients; a mean peak CK-MB of 35 IU/l occurred 2 h postoperatively.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1990

Initiating activity of 3-tert-butyl-4-hydroxyanisole (3-BHA) and its metabolites in two-stage transformation of BALB/3T3 cells.

3-tert-Butyl-4-hydroxyanisole (3-BHA) and its metabolites, tert-butyl-1,4-benzoquinone (BQ) and 3-tert-butyl-5-methoxy-1,2-benzoquinone (BHAoQ), were tested for initiating activity in a two-stage transformation assay using BALB/3T3 cells. Cells were treated first with a test chemical and then with the tumor promoter 12-O-tetradecanoylphorbol 13-acetate (TPA). In the absence of TPA the test chemicals did not induce cell transformation. With the promoting treatment, 3-BHA and BQ induced dose-dependent cell transformation. There were statistically significant increases in the proportion of dishes with transformed foci in the cultures treated with 30 micrograms/ml 3-BHA plus TPA (15 of 24 dishes, P less than 0.005) and with 0.4 microgram/ml BQ plus TPA (12 of 22 dishes, P less than 0.02) as compared to the cultures treated with DMSO plus TPA (5 of 24 dishes). BHAoQ caused a non-significant increase in transformation frequency in the presence of TPA. In conclusion, 3-BHA and BQ had an initiating activity in the cell transformation system and the potency of BQ was approximately 100 times higher than that of 3-BHA.

Animals↗
PubMed1990

Structure and molecular analysis of RGR1, a gene required for glucose repression of Saccharomyces cerevisiae.

An RGR1 gene product is required to repress expression of glucose-regulated genes in Saccharomyces cerevisiae. The abnormal morphology of rgr1 cells was studied. Scanning and transmission electron microscopic observations revealed that the cell wall of the daughter cell remained attached to that of mother cell. We cloned the RGR1 gene by complementation and showed that the cloned DNA was tightly linked to the chromosomal RGR1 locus. The cloned RGR1 gene suppressed all of the phenotypes caused by the mutation and encoded a 3.6-kilobase poly(A)+ RNA. The RGR1 gene is located on chromosome XII, as determined by pulsed-field gel electrophoresis, and we mapped rgr1 between gal2 and pep3 by genetic analysis. rgr1 was shown to be a new locus. We also determined the nucleotide sequence of RGR1, which was predicted to encode a 123-kilodalton protein. The null mutation resulted in lethality, indicating that the RGR1 gene is essential for growth. On the other hand, a carboxy-terminal deletion of the gene caused phenotypes similar to but more severe than those caused by the original mutation. The amount of reserve carbohydrates was reduced in rgr1 cells. Possible functions of the RGR1 product are discussed.

Alleles↗
PubMed1990

Effective purification of human chorionic gonadotropin and its subunits from pregnant women's urinary peptides absorbed on reverse-phase resin.

Human chorionic gonadotropin (hCG) was extracted and purified by reverse-phase resin (Sepralyte C8 resin) adsorption and Sephadex G-100 column chromatography from urine of pregnant women. Approximately 15000 IU of hCG was recovered from 1000 ml of urine by C8 resin adsorption. hCG from the gel-filtration step stimulated testosterone production in rat Leydig cells and had a specific activity of approximately 8000 IU/mg, a value which was higher than those of commercial hCGs. Furthermore, hCG purified to near-homogeneity was separated effectively into its subunits by reverse-phase high-performance liquid chromatography using an acetonitrile gradient in the presence of 0.1% trifluoroacetic acid with no special pretreatment for dissociation of subunits. The separated subunits were able to re-associate. The techniques used are simple and may be suitable for not only laboratory but also industrial production of hCG and its subunits.

Animals↗
PubMed1990

Pulmonary circulation during exercise in rats.

Pulmonary arterial pressure of treadmill-running rats became significantly higher than the sedentary control level, while systemic arterial pressure did not rise. The rise of pulmonary arterial pressure seemed to be accompanied with the increase of cardiac output.

Animals↗