Biomedical subjects

S Yuasa

Publications and source records attributed to S Yuasa.

At least 73 records · Page 4Linked to original sources

PubMed1997

Functional changes of rat brain microsomal membrane surface after learning task depending on dietary fatty acids.

Biochemical characteristics of brain microsomal membranes were examined before and after the brightness-discrimination learning tasks in rats that were fed either safflower oil (alpha-linolenate-deficient) or perilla oil (alpha-linolenate-sufficient) diets. We detected small changes in the chain elongation system for polyunsaturated fatty acids in microsomes, whereas no significant difference was detected in the inositol trisphosphate-induced calcium release and ATP-induced calcium uptake profiles of microsomes between the two dietary groups. The calcium ion-induced aggregation rate of microsomes was determined in both groups. We found that the aggregation rate of microsomes in the safflower oil group was significantly greater than that in the perilla oil group. The difference in susceptibility of microsomal membrane phospholipids to phospholipase A2 between the groups was obvious, and the amount of released fatty acids by phospholipase A2 from the perilla oil group microsomes was nearly half of that from the safflower oil group microsomes after the learning task. Susceptibility of sialic acids on the brain microsomal membranes to exogenous sialidase was different only after the learning task in the safflower and perilla oil groups. These results suggest that the biochemical characteristics of membrane surfaces of brain microsomes are affected significantly by the learning task itself in a dietary oil-dependent manner.

Animals↗

PubMed1997

Identification of a new cellular protein that can interact specifically with DAN.

Recently, we demonstrated that the DAN gene product contains a growth- and/or a tumor-suppressive activity in vitro. In the present work, using a yeast two-hybrid system, we searched for cellular proteins that can associate with the DAN gene product. A cDNA clone, termed DA41, was initially isolated from an adult rat lung cDNA library. The DA41 gene was expressed in all adult tissues examined, however, the levels of expression varied significantly among the different tissues. Like the DAN gene product, the DA41 protein was similarly restricted to the cytoplasm. Sequence analysis revealed that DA41 cDNA is 2,167 nucleotides in length and contains a single open reading frame (ORF) of 582 amino acids (61,945 daltons). A homology search revealed that the DA41 gene product shares no structural similarity with those filed in the data base. In a synchronous 3Y1 cell culture, DA41 mRNA was expressed at a low level in quiescent cells; however, its level was significantly increased between the G1 and S phases of the cell cycle. On the other hand, the expression level of DAN mRNA did not change throughout the cell cycle progression. These results suggest that the DAN-DA41 complex might play a crucial role in the regulation of the cell cycle progression.

Adaptor Proteins, Signal Transducing↗

PubMed1997

Chronic animal experiment with magnetically suspended centrifugal pump.

We have been developing a new type of centrifugal pump for long-term use. The magnetically suspended centrifugal pump (MSCP) contains no shaft and seal so that long life expectancy is predicted. Paracorporeal left ventricular (LV) assist circulation between the left atrium and the descending aorta was instituted using sheep. The flow rates ranged from 2.5-5.5 L/min. The sheep that lived the longest (46 days) died of an embolism as a result of the thrombus in the pump. No thrombus formation was observed in other pumps. Plasma free hemoglobin levels ranged from 9 to 18 mg/dl, which led to the conclusion that the hemolysis level remained within an acceptable range. Two driving modes were compared. The slope of the pressure-flow relationship plot under a constant motor current mode was steeper than that under a constant rotational speed mode, and thus, the flow fluctuation decreased. In conclusion, the MSCP is durable for more than a month at the current stage of development and is a promising device for long-term ventricular assist.

Animals↗

PubMed1997

[Long-term follow-up study of bone mineral density in a patient with adult idiopathic Fanconi syndrome].

A 64-year-old woman complaining of severe lumbar pain was admitted to our hospital because of the finding of pre-existing mitral valve regurgitation on examination. Laboratory data revealed the proximal type of renal tubular acidosis, renal glucosuria, phosphaturia, generalized aminoaciduria and low-molecular-weight proteinuria. She did not have any cause of these tubular dysfunctions, and was diagnosed as adult idiopathic Fanconi syndrome. Dual energy X-ray absorptiometry (DEXA) revealed a reduction of bone mineral density in the lumbar spine to about 65% of the age-and gender-matched control value. Alkali agents (sodium citrate and potassium citrate), calcium lactate and 1 alpha-hydroxyvitamin D3 were administered. Bone mineral density estimated with DEXA improved with a reduction of serum alkali phosphate and disappearance of lumbar pain, and was restored to 82% of the age-and gender-matched control value after about 30 months of treatment. DEXA is useful for the long-term follow-up study of bone mineral density in a patient with Fanconi syndrome.

Absorptiometry, Photon↗

PubMed1997

[A case of scheduled mitral valve replacement for mitral regurgitation caused by papillary muscle rupture after acute myocardial infarction].

Mitral regurgitation caused by papillary muscle rupture after acute myocardial infarction has poor prognosis, and it is the usual course for such cases in cardiogenic shock to be performed early mitral valve replacement. However, we recently experienced a case of successful scheduled mitral valve replacement for mitral regurgitation caused by rupture of the posterior papillary muscle after acute inferior myocardial infarction. The patient was a 63-year-old woman who admitted to a hospital with back pain and dyspnea and was diagnosed as pulmonary edema due to mitral regurgitation after acute myocardial infarction. She was treated with dopamine and diuretic agents effectively, but not weaned from these drugs. Then, she was transferred to our hospital. At the admission, she was in the NYHA class II due to mitral regurgitation and inferior myocardial infarction with papillary muscle rupture revealed by transesophageal echocardiography. Cardiac catheterization demonstrated total occlusion of the proximal right coronary artery (segment #2) and mitral regurgitation in Sellers III. The patient underwent a successful scheduled mitral valve replacement with SJM 27M concomitant with coronary artery bypass grafting 47 days after the onset of acute mitral regurgitation. There are few reports that successful surgical treatment for papillary muscle rupture was done more than 4 weeks after the onset of mitral regurgitation in Japan.

Female↗

PubMed1997

[Investigation of complications of bronchial artery embolization using superselective catheter system and platinum coil-major complications as vascular detachment].

We have performed bronchial artery embolization (BAE) in patients with hemoptysis using a superselective catheter system and a permanent-emboli coil. We performed an investigation because major complications were observed. Of a total of 57 BAE using this system, 7 cases of major complications as detachment of the large vessel were found. Although BAE using this system is effective because permanent emboli can be selectively in-dwelled in abnormally developing vessels, detachment of vessels were developed in 7 cases. They are found more frequently for embolization of the left bronchial artery and full attention should be paid to this phenomenon when performing this surgery.

Adult↗

PubMed1997

[Preoperative autologous transfusion--its methods and clinical usefulness].

In spite of continuing development in transfusion medicine, homologous transfusion accompanies risks and problems, such as viral infection, alloimmunization, transfusion associated GVHD and immunosuppressive reactions. To avoid these risks of homologous transfusion, autologous blood transfusion has been introduced as the safest blood transfusion. Here, methods of predeposit autologous blood transfusion and its clinical usefulness are described. There are two methods for predeposit autologous transfusion; Liquid preservation and frozen preservation. The merit of the former is easy and economical, but 3 units (1200 ml) will be maximum volume to collect in 3 weeks before surgery. While frozen preservation, patient can predeposit the necessary amount of blood without affecting their preoperative condition, as we can set the intervals of blood collections more than 3 weeks, and blood can be stored up to 10 years. However this method requires equipment and cost more.

Blood Preservation↗

PubMed1997

[Clinical study of the application of the concepts of systemic inflammatory response syndrome (SIRS) in liver cirrhosis with or without hepatocellular carcinoma with upper gastrointestinal hemorrhage--a retrospective study].

The retrospective study was aimed at assessing the usefulness of the application of the criteria of SIRS for identifying a subset of patients with higher mortality in 22 cases (21 patients) of liver cirrhosis with upper gastrointestinal hemorrhage (GIH) and 16 cases (14 patients) of liver cirrhosis with hepatocellular carcinoma with upper GIH. The following results were obtained; (1) The incidence of SIRS on upper GIH was 66%. (2) The mortality rate in patients with SIRS on GIH was significantly higher than in patients with non-SIRS on GIH in 60 days after GIH was significantly higher than in patients with non-SIRS on GIH in 60 days after GIH (50% vs. 8%; p < 0.01). (3) The rate of patients who met four criteria of SIRS on GIH or during admission and of patients whose durations of SIRS was over 5 days was significantly higher in the died patients with SIRS on GIH than in the survived patients with SIRS on GIH (67% vs. 0%; p < 0.01, 67% vs. 0%; p < 0.01, respectively). These results suggested that the application of the criteria of SIRS was useful for identifying a subset of patients with higher mortality in chronic liver disease with GIH.

Adult↗

PubMed1997

[Mechanism mediating hypertension induced by chronic inhibition of nitric oxide synthesis].

Although the inhibition of nitric oxide (NO) synthesis is known to induce systemic hypertension, the underlying mechanisms mediating this type of hypertension are incompletely understood. In the present study we investigated the influence of sodium intake on the pressor effect of long-term administration of the NO synthesis inhibitor, NG-nitro-L-arginine methyl ester (L-NAME, 16 mg/dl in drinking fluid for 8 weeks), in conscious Sprague-Dawley rats. Urinary excretion rates of catecholamine during NO synthesis inhibition were also examined. Long-term administration of L-NAME produced a sustained elevation in tail-cuff pressure without altering urine flow, or sodium excretion rate. L-NAME-induced hypertension was accompanied by a decreased urinary excretion of the stable NO metabolites, NO2- and NO3-, and was aggravated when rats drank 0.9% saline in place of tap water. Thus, inhibition of NO synthesis resulted in a rightward shift of the pressure natriuresis relationship and a significant decrease in the slope of this relationship. Urinary excretion of epinephrine and norepinephrine, but not that of dopamine, in L-NAME-treated rats significantly increased within the first week of the study when compared with those observed in control rats. A natriuretic index of the sympathetic nervous system, the ratio of dopamine to norepinephrine excretion, was significantly less in L-NAME-treated rats than in control rats. After 8-week treatment with L-NAME, renal morphologic evaluation revealed significant narrowing and obliteration of the arterioles. L-arginine (2 g/dl in drinking fluid) completely reversed the elevation of blood pressure as well as the decrease in urinary NO2- and NO3- excretion and the increased urinary excretion of catecholamines associated with L-NAME treatment after 3 weeks of concomitant administration. These results suggest that the inhibition of chronic NO synthesis produces sodium-sensitive hypertension and that changes in sympathetic nerve activity may, at least in part, contribute to the sodium sensitivity in this type of hypertension.

Animals↗

PubMed1996

Enzymatic characterization of purified NS3 serine proteinase of hepatitis C virus expressed in Escherichia coli.

Non-structural protein 3 (NS3) of the hepatitis C virus (HCV) has been shown to be a serine proteinase which cleaves the HCV polyprotein thus activating its replicative machinery. To characterize enzymatic activities of NS3 serine proteinase, the proteinase region was expressed in Escherichia coli and purified. The purified proteinase specifically cleaved a purified fusion protein sandwiching the NS5A/5B cleavage sequence. In addition to serine proteinase inhibitors, some chelators also inhibited the cleavage activity. Metal ions were not required for its activity, suggesting that the proteinase may be a novel serine proteinase having a unique binding site for chelators.

ATP-Binding Cassette Transporters↗

PubMed1996

Bergmann glial development in the mouse cerebellum as revealed by tenascin expression.

Tenascin, an astroglia-derived extracellular matrix molecule, is also expressed by radial glia of the embryonic mouse cerebellum. Expression of tenascin can thus be applied as a marker of astroglial development from an early stage, especially prior to the expression of the glial fibrillary acidic protein (GFAP) that can be detected in the postnatal cerebellum. The development of Bergmann glia, specialized cerebello-cortical astroglia with radial processes, was examined by tenascin immunohistochemistry and non-radioactive in situ hybridization histochemistry for tenascin mRNA in the developing mouse cerebellum. Tenascin-immunopositive radial glial processes extending from the ventricular zone to the pia mater retracted toward the cortex in the embryonic cerebellum and occupied a position corresponding to the Bergmann glial processes at the perinatal stage. Tenascin gene-expressing cells were generated in the ventricular zone of the cerbellar primordium and migrated radially toward the cortex. They were stratified in the layer of Bergmann glial somata at the early postnatal stage. They extended GFAP-immunopositive radial processes from the somata to the pia mater as revealed by double-labeling employing tenascin in situ hybridization histochemistry and GFAP-immunostaining. Bergmann glia are therefore considered to develop from cerebellar radial glia by migration of their somata and retraction of their processes. The tenascin gene-expressing cells displayed mitotic activity after alignment in the cortex as revealed by double-labeling by tenascin in situ hybridization histochemistry and immunohistochemical detection of the incorporated bromodeoxyuridine. The above findings suggest that the Bergmann glia in the cortex represent one of the origins of the astroglia in the developing cerebellum.

Age Factors↗

PubMed1996

Complete inhibition of viral breakthrough by combination of MKC-442 with AZT during a long-term culture of HIV-1 infected cells.

We have investigated viral breakthrough during a long-term culture of HIV-1-infected cells with the non-nucleoside reverse transcriptase inhibitors (NNRTIs) 6-benzyl-1-ethoxymethyl-5-isopropyluracil (MKC-442), nevirapine and loviride (alpha-APA). When the compounds were examined for their inhibitory effects on HIV-1 (HE strain) replication in MT-4 cells on day 4 after virus infection, the 50% effective concentrations (EC50) of MKC-442, nevirapine and loviride were 9.4, 98 and 21 nM, respectively. After a 48-day culture period, MKC-442, nevirapine and loviride completely inhibited viral breakthrough at concentrations of 1, 5 and 1 microM, respectively. These concentrations were 50-100-fold higher than their EC50 values. When the cells were treated with either MKC-442 (0.04 and 0.2 microM), nevirapine (0.2 and 1 microM) or loviride (0.04 and 0.2 microM) in combination with AZT (0.005 microM), only the combination of 0.2 microM MKC-442 with 0.005 microM AZT could completely inhibit the breakthrough of HIV-1 after a 68-day culture period. Polymerase chain reaction (PCR) analysis revealed that no proviral DNA was detected in the cells treated with this combination. Except for two combinations (0.04 microM MKC-442 + 0.005 microM AZT and 0.04 microM loviride + 0.005 microM AZT), all of the viruses isolated during combination treatments had various amino acid mutations in their reverse transcriptase (RT). These results indicate that the combination treatment with a relatively high dose of MKC-442 and a low dose of AZT may have potential to suppress the emergence of drug resistance during a long-term treatment in vivo and should be further pursued in HIV-1-infected patients.

Acetamides↗

PubMed1996

Alleviation of cisplatin nephrotoxicity: efficacy of local intra-arterial injection concomitant with hemodialysis.

Although cis-diamminedichloroplatinum (cisplatin) is widely used in the treatment of malignant tumors, the dose administered is limited because of side effects such as nephrotoxicity. The plasma levels of non-protein-bound platinum, which can be removed by dialysis, play an important role in the antitumor effects and the appearance of side effects. Selective intra-arterial injection of cisplatin during concomitant hemodialysis (HD) was performed in patients with gynecological malignancies. At a dose of 100 mg, about three times the non-protein-bound platinum excreted in the urine during the same period was removed by HD. The area under the time-concentration curve of plasma total platinum up to 5 h after intra-arterial injection was reduced by 46%. When doses of 200 or 250 mg were administered concomitantly with HD, the maximum plasma levels were suppressed to about the same degree as when 100 mg were injected without concomitant HD. A definite reduction in the incidence of side effects was seen, and a reduction in the severity of nephrotoxicity was also observed when 100 mg were given with HD. No severe side effects were found even when 200 or 250 mg were administered with concomitant HD. The antitumor effects were not reduced or possibly potentiated, but follow-up is still of short duration. These results indicate that chemotherapy with local intra-arterial injections of cisplatin using concomitant HD not only reduces systemic side effects, in particular nephrotoxicity, but also allows for increased doses at the tumor site and can be applied in patients with renal dysfunction.

Acetylglucosamine↗

PubMed1996

Antineutrophil cytoplasmic antibodies (ANCA)-associated crescentic glomerulonephritis and propylthiouracil therapy.

Cutaneous vasculitis is an uncommon complication of propylthiouracil therapy. Although its pathogenesis remains to be established, detection of antineutrophil cytoplasmic antibodies (ANCA) in association with this type of vasculitis has recently been described. We report here 2 patients who developed ANCA-associated crescentic glomerulonephritis without evidence of cutaneous vasculitis during propylthiouracil treatment of hyperthyroidism. Improvement of the renal function and the disappearance of ANCA were correlately found after discontinuation of propylthiouracil and by corticosteroid therapy in both patients.

Adult↗

PubMed1996

A high linoleate and a high alpha-linolenate diet induced changes in learning behavior of rats. Effects of a shift in diets and reversal of training stimuli.

Rats fed from weaning on semi-purified diets supplemented either with linoleate-rich safflower oil (S) or alpha-linolenate-rich perilla oil (P) were mated. Half of the progeny were weaned to the original diet of the dams (SS and PP), the other two groups were shifted to diets enriched in the other fatty acid (SP and PS). Brightness-discrimination learning ability was tested daily for 30 d beginning at 11 weeks of age, with a bright light as the positive stimulus. The learning performance was inferior in the group fed the safflower diet through two generations (SS) as compared with groups fed the perilla diet through two generations (PP) or for which the diets were shifted at weaning (PS and SP). The docosahexaenoate content of brain phospholipids was significantly less in the SS group compared with the three other groups. After 30 d of the learning test, the effect of shifting the stimulus was tested for another 30 d, this time using a dim light as the positive stimulus. The learning performance was superior in the PP group to the SS group throughout the latter 30 sessions, the difference being even more obvious than during the first 30 d. These results indicate that the decrease in the discrimination-learning ability induced by alpha-linolenate deficiency is a relatively reversible process; both the docosahexaenoate content in brain and the learning performance were restored by supplementing alpha-linolenate after the weaning.

Animals↗

PubMed1996

[Synthesis of stable solvates of monosodium 2-[Rs,9S)-(4-methoxy-6,7,8, 9-tetrahydro-5H-cyclohepta[b]pyridin-9-yl)sulfinyl]-1H-benzimidazole].

Monosodium 2-[(R*s,9S*)-(4-methoxy-6,7,8, 9-tetrahydro-5H-cyclohepta-[b]pyridin-9-yl)sulfinyl]-1H-benzimidazole (3A), a novel antiulcer agent previously reported by us, was found to be easily decomposed in weakly acidic solutions. In order to improve the stability of the parent compound, 3A, the preparation of 1-substituted benzimidazoles (4A) was attempted. However, the inhibitory effect of 4A against gastric acid secretion was less potent than that of 3A. Then 3A was solvated by EtOH or H2O to afford 5A or 6A, respectively. On the other hand, an another diastereoisomer, (R*s,9R*)-3B, was not solvated by EtOH or H2O under the same conditions. The thus obtained solvates (5A, 6A) are much more stable than that of 3A. The antiulcer activities of 5A and 6A were found to be similar to that of the parent compound (3A). Consequently, 6A was selected as an antiulcer agent for the development.

Animals↗

PubMed1996

Effect of low dietary calcium intake on blood pressure and pressure natriuresis response in rats: a possible role of the renin-angiotensin system.

Dietary Ca is an important modulator of blood pressure in humans and rats. Since the kidney plays a key role in the pathogenesis of hypertension, the effects of a low Ca diet (0.01% Ca) on blood pressure and pressure natriuresis response were studied in normotensive Sprague-Dawley rats. In addition, a possible role of the renin-angiotensin system in the development of hypertension and an altered pressure natriuresis response resulting from low dietary Ca intake was examined. In the low Ca diet group, systolic blood pressure measured by the tail-cuff method was significantly higher than in the normal Ca diet group (1,1% Ca) 1 week after the diet (1 13.0 +/- 7.1 vs. 105.0 +/- 9.5mmHg, p < 0.05). After 4 weeks, the hypertension was more pronounced. Low dietary Ca intake significantly inhibited the water and sodium excretory responses to acute elevation of renal perfusion pressure by tightening an infrarenal aortic constriction. Treatment with an inhibitor of angiotensin-converting enzyme, captopril (30 mg/kg/day), completely abolished the elevation of blood pressure and attenuated the reduced pressure natriuresis response observed in Ca-deficient rats. Although plasma renin activity was not different between the low and normal Ca diet groups after the 2-week dietary regimen, the pressor response to angiotensin II was enhanced by 30% in the low Ca diet group and there was a significant difference in the pressor response between the two groups. These results suggest a possible involvement of the renin-angiotensin system in the development of hypertension and an inhibitory effect on the pressure natriuresis response caused by low dietary Ca intake, via an enhanced sensitivity to angiotensin II.

Analysis of Variance↗

PubMed1996

Neuron-glia interrelations during migration of Purkinje cells in the mouse embryonic cerebellum.

The interrelations between migratory Purkinje cells and radial glial processes were examined immunohistochemically and electron-microscopically in the fetal mouse cerebellum. Migratory Purkinje cells identified immunochemically with anti-spot 35 antibody were apposed to the presumed radial glial processes. Putative immature migratory Purkinje cells were apposed to the radial glial processes identified immunochemically with monoclonal antibody 1D11 or anti-tenascin antibody. Junctional specializations related to cell adhesion were observed at the sites of contact between the immature neurons and glial processes. Furthermore, coated vesicles and coated pits were noted in the contact region. These findings support the concept of contact guidance of migratory Purkinje cells by radial glial processes through cell adhesion, and also suggest the trophic interactions occurring at the region of contact.

Animals↗