Biomedical subjects

K Asano

Publications and source records attributed to K Asano.

At least 127 records · Page 7Linked to original sources

PubMed1998

Structural basis for binding of the plasmid ColIb-P9 antisense Inc RNA to its target RNA with the 5'-rUUGGCG-3' motif in the loop sequence.

The sequence 5'-rUUGGCG-3' is conserved within the loop regions of antisense RNAs or their targets involved in replication of various prokaryotic plasmids. In IncIalpha plasmid ColIb-P9, the partially base paired 21-nucleotide loop of a stem-loop called structure I within RepZ mRNA contains this hexanucleotide sequence, and comprises the target site for the antisense Inc RNA. In this report, we find that the base pairing interaction at the 5'-rGGC-3' sequence in the hexanucleotide motif is important for interaction between Inc RNA and structure I. In addition, the 21-base loop domain of structure I is folded tighter than predicted, with the hexanucleotide sequence at the top. The second U residue in the sequence is favored for Inc RNA binding in a base-specific manner. On the other hand, the upper domain of the Inc RNA stem-loop is loosely structured, and maintaining the loop sequence single-stranded is important for the intermolecular interaction. Based on these results, we propose that a structural feature in the loop I domain, conferred probably by the conserved 5'-rUUGGCG-3' sequence, favors binding to a complementary, single-stranded RNA. This model also explains how the RepZ mRNA pseudoknot, described in the accompanying paper (Asano, K., and Mizobuchi, K. (1998) J. Biol. Chem. 273, 11815-11825) is formed specifically with structure I. A possible conformation adopted by the 5'-rUUGGCG-3' loop sequence is discussed.

Bacterial Proteins↗

PubMed1998

CD4+ T cells from peripheral blood of a melanoma patient recognize peptides derived from nonmutated tyrosinase.

Tyrosinase is an antigen that is expressed by normal melanocytes as well as melanoma cells, against which responses by autologous T cells have been detected. Although CD4+ T cells play an important role in tumor immunity in animal tumor models, little information about CD4+ T-cell immunity against human tumors exists. Here, we report that CD4+ T cells from the peripheral blood of a patient with melanoma respond to synthetic peptides derived from nonmutated tyrosinase. T-cell clones were generated that recognized the tyrosinase p386-406 peptide when it was presented by the HLA-DR15 (DRB1*1501) molecule. The CD4+ T-cell clone also recognized autologous EBV-transformed B-lymphoblastoid cell lines that had been pulsed with the lysate of melanoma cells. The synthetic tyrosinase p386-406 peptide was capable of binding to HLA-DR15 (DRB1*1501) molecules on cell surface of DR15 homozygous cells. Thus, the finding that nonmutated tyrosinase peptides are immunogenic in a melanoma patient may provide the basis for the development of cancer immunotherapy, based on knowledge of synthetic tumor-associated peptide antigens.

Antigen-Presenting Cells↗

PubMed1998

Effects of Postoperative Pericardial Effusion on Coronary Artery Bypass Grafts: A Study with X-ray Computed Tomography.

The aim of this study was to evaluate the effects of pericardial effusion on coronary artery bypass grafts and their patency using X-ray computed tomography (CT). Uncontrasted CT of horizontal sections from the lower margin of the aortic arch to the left ventricle was done at 5-mm intervals. In one cross-section of the pulmonary bifurcation level, 30 ml of a contrast media (lohexol 350) was injected at a rate of 3 ml/second into the antecubital vein. All slices of uncontrasted CT were analyzed for the presence or absence of effusion. The severity was expressed as the maximum value of the thickness of effusion. CT was repeated about every 6 months postoperatively under the same conditions. Selective angiography was also performed 7.1 +/- 3.9 months postoperatively. A total of 46 patients (mean age 57 years) underwent CT and angiography. A total of 95 grafts were implanted: 90 saphenous veins and 5 internal thoracic arteries. Selective angiography revealed that 79 grafts were patent and 16 were occluded. The first postoperative CT (at 2.6 +/- 2.1 months) showed the retention of effusion in all patients. The mean maximum value was 1.0 +/- 0.5 cm; there were no significant differences between patent grafts (1.0 +/- 0.5 cm) and occluded grafts (1.0 +/- 0.5 cm). Occlusion was found in 10 grafts by the first CT (2.9 +/- 2.7 months postoperatively) and another 6 grafts by the second CT (11.3 +/- 4.2 months). Thereafter, all grafts were patent. Previously occluded grafts showed no cross-section images on uncontrasted or contrasted CT. Except for two grafts, all patent grafts could be observed even without contrast enhancement. The remaining two grafts were masked with effusion, but patency was confirmed by a contrast media. In conclusion, retention of effusion does not affect the patency of grafts. Occlusion occurs early after surgery, and grafts cannot be imaged on CT. Patent grafts can be observed by uncontrasted CT, as well as contrasted CT, except where a large amount of effusion is present.

Journal Article↗

PubMed1998

Comparisons of serum testosterone and corticosterone between exercise training during normoxia and hypobaric hypoxia in rats.

The purpose of this study was to compare the effects of continuous and intermittent exercise training on serum testosterone [T] and corticosterone concentrations [Cort] during normoxia and hypobaric hypoxia. Male rats swam with loads of 3% (normoxia) or 2.25% (462 mmHg) body mass for 60 min in the continuous training groups, and 15 min separated by a 7-min rest x 4, with 60-min total exercise duration in the intermittent training groups, 5 days week(-1) for 6 weeks. Serum [T] were measured at rest and following exercise after 6 weeks of training. Serum [Cort] were measured immediately after an acute period of exercise or after 6 weeks of training at rest and following exercise. Continuous exercise induced decreases in [T] under both conditions. Intermittent exercise showed a tendency to increase [T] during normoxia, but caused a suppression during hypobaric hypoxia. The [Cort] was elevated by a similar margin after an acute period of exercise during both conditions. After 6 weeks of training, however, [Cort] increased slightly after exercise during normoxia. A lower resting [Cort], which was increased after exercise, was found in the training groups during hypoxia. No relevant relationship was found between the behaviours of [T] and [Cort] after exercise during either conditions.

Animals↗

PubMed1998

A period of anaerobic exercise increases the accumulation of reactive carbonyl derivatives in the lungs of rats.

It is known that acute physical exercise may have diverse pathophysiological consequences in various organs due to free radical formation. We have investigated whether a period of anaerobic running to exhaustion in rats results in oxidative modification of proteins in the lungs. Six rats of an exercised group (E) ran for two periods of 5 min at a speed of 30 m.min-1 followed by a recovery period of 5 min, and then by a third period of running to exhaustion. Reactive carbonyl derivatives (RCD) were measured by the Western blot technique on lungs of E and control (C) rats. In addition, the activity of glutamine synthetase (GS) was also monitored as marker of oxidative damage to proteins. This investigation revealed significant exercise-induced increases in accumulation of RCD in the lungs of the E group compared with the C group. The RCD signals were visibly stronger in proteins with molecular weight of 55 kDa and 32 kDa. The activity of GS was higher by about 30% in E rats than in C rats. The present data suggest that anaerobic exercise induces protein oxidation in the lungs.

Anaerobiosis↗

PubMed1998

The effect of high altitude and caloric restriction on reactive carbonyl derivatives and activity of glutamine synthetase in rat brain.

Both exposure to high altitude (HA) and caloric restriction (CR) may influence free radical generation. The aim of the present study was to evaluate the effects of 4 wk chronic exposure to 4,000m of HA and CR (60% of CR of control (C) rats) on protein oxidation in brain. Eighteen rats with similar body mass were assigned to CR, HA and C rats. Reactive carbonyl derivatives (RCD), marker of protein oxidation, were measured by Western blot. In addition, the activity and protein content of glutamine synthetase (GS) were determined. The body mass of C rats was significantly higher (P< 0.001) than that of HA and CR groups. The quantified signal intensity of RCD was significantly stronger in C rats than in HA and CR rats. The activity of GS was significantly increased in CR rats, while the protein content of GS was decreased in HA rats compared to C group. The data suggest that both HA and CR decreases the accumulation of RCD in the brain, however the mechanism of the decrease seems to be different during HA and CR.

Altitude↗

PubMed1998

Biotransformation of shiromodiol diacetate, myli-4(15)-en-9-one and myliol by Aspergillus niger.

Microbiol biotransformation of shiromodiol diacetate from Neolitsea serisea koids, and of myli-4(15)-en-9-one and myliol from the liverwort Mylia taylorii, were carried out with Aspergillus niger IFO 4407. A. niger hydroxylated the allyl position (C-2) of shiromodiol diacetate, and one of the geminal dimethyl groups of myli-4(15)-en-9-one and myliol regioselectively. The structures of these transformants were elucidated by spectral analysis and confirmed by X-ray analysis.

Aspergillus niger↗

PubMed1998

Suppressive effects of Tripterygium wilfordii Hook f., a traditional Chinese medicine, on collagen arthritis in mice.

The effect of chloroform extract of Tripterygium wilfordii Hook f. (TWH extract), a traditional immunosuppressive Chinese herb, on type II collagen (C II)-induced arthritis (CIA) in DBA/1J mice was studied. In the first set of experiments, we examined the effect of TWH extract on cellular immune responses to C II. As compared with mice treated with saline, TWH extract administered orally at doses of more than 400 microg kg(-1) once a day for 14 days inhibited the ability of inguinal lymph node cells to produce T cell cytokines interleukin-2 and interferon-gamma when the cells were obtained from mice 21 days after immunization and cultured in vitro with C II. Treatment with TWH extract also inhibited production of macrophage cytokines interleukin-1beta and tumor necrosis factor-alpha in response to in vitro stimulation of lymph node cells with C II. In the second part of the experiment, we evaluated the influence of TWH extract on the incidence and development of arthritis in murine CIA. Mice were immunized twice at a 3-week interval with bovine C II, with TWH extract being given orally once a day for 14 days with four different regimens. A 14-day course of TWH extract treatment at a daily dose of 400 microg kg(-1), which began on the day of the first C II immunization, suppressed the development of arthritis, as well as antibody production and delayed-type hypersensitivity to C II. Treatment with TWH extract, which started on the same day as the booster immunization, also resulted in inhibition of development of arthritis and of immune responses to C II. On the other hand, therapeutic administration with TWH extract did not affect the clinical course of the disease and the immune response to C II.

Animals↗

PubMed1998

An increase of soluble Fas, an inhibitor of apoptosis, associated with progression of COPD.

In chronic obstructive pulmonary disease (COPD) which consists of emphysema and chronic bronchitis, alveolar tissue and/or bronchiolar walls are progressively destroyed. This suggests cell death by necrosis and/or apoptosis although no direct evidence of apoptosis has been reported. It was speculated that the apoptosis-related factors are associated with the progression of COPD. Fas/Apo-1 receptor (Fas), Fas ligand (Fas-L) and soluble Fas ligand (sFas-L) are inducers, while soluble Fas (sFas) is an inhibitor of apoptosis. In this study, plasma sFas and sFas-L were measured in 19 COPD patients receiving supplemental O2 (severe COPD) and 20 COPD patients not receiving supplemental O2 (mild/moderate COPD). Twenty-two age- and sex-matched healthy volunteers (healthy controls) and 20 patients receiving supplemental O2 and with level of hypoxaemia similar to severe COPD due to other pulmonary diseases (disease controls) were also examined. Plasma sFas-L was within normal limits in all groups. Plasma sFas levels were similar among healthy controls, disease controls, and mild/moderate COPD patients, but significantly increased in severe COPD (2.6 +/- 1.1, 2.6 +/- 0.2, 2.8 +/- 0.2 and 4.8 +/- 1.0 ng ml-1, respectively). Although PaO2 was lower in severe COPD than in mild/moderate COPD, and PaCO2 was higher in severe COPD than in mild/moderate COPD, they were close between severe COPD and disease controls. Tumour necrosis factor-alpha (TNF-alpha), interleukin 6 (IL-6) and C-reactive protein (CRP) were increased in patients with COPD, but were similar in both severe and mild/moderate COPD patients. We conclude that increased plasma sFas, which is independent of hypoxaemia, and increases in PaCO2, TNF-alpha, IL-6 and inflammation, may be associated with progression of COPD.

Aged↗

PubMed1998

Eosinophil chemotactic factors from cysticercoids of Hymenolepis nana.

A comparative study of eosinophil chemotactic factors was carried out using cysticercoids and oncospheres of Hymenolepis nana. Cysticercoids showed twice the chemotactic activity for eosinophils than the oncospheres. Eosinophilia induced by oncospheres and cysticercoids observed in secondary and primary infections, respectively, were discussed from the view point of the immunobiology of this parasite.

Animals↗

PubMed1998

Increase in serum vascular endothelial growth factor levels during altitude training.

The present study was performed to evaluate the effects of physical exercise at altitudes on serum vascular endothelial growth factor (VEGF) levels. Eight subjects underwent intensive swimming training for 21 days at 1886 m. After altitude training commenced, red blood cell (RBC) counts and erythropoietin levels increased, but both haemoglobin and haematocrit levels did not change significantly. The serum level of VEGF, measured by means of a highly sensitive chemiluminescence (ELISA), showed a transient decrease 10 days after start of the altitude training, thereafter increasing significantly to reach a peak level 19 days later, rising from 23.0 +/- 5.3 to 46.0 +/- 14.6 pg mL-1 (P < 0.05 vs. before). On return to low altitude in Japan, the level of VEGF decreased, and 1 month later had returned to initial levels. Endurance training at altitudes increases serum VEGF levels; this could be an adaptive reaction to hypoxic conditions. This result suggests that VEGF may provide a new physiological parameter for hypoxic stress imposed by high altitude training.

Adult↗

PubMed1998

Ultrasonographic and serologic studies of experimental cysticercosis in rats infected with Taenia taeniaeformis.

Rats experimentally infected with Taenia taeniaeformis were followed-up until 14 weeks post inoculation with eggs (PIE) by hepatic ultrasonographic (US) image and serum antibody response analyses. Parasitic cysts could be imaged as small (2 mm in diameter) anechoic areas with or without a parenthesis-like echogenic small line from two weeks PIE. Immunoblot analysis using antigens from oncospheres (TtO), 30-day-old (TtM-30) and 300-day-old metacestodes (TtM-300) revealed that: (1) these three different developmental stages showed their own unique patterns suggesting the presence of stage-specific antigens; (2) faint IgM antibody responses to some components of TtO and TtM-30 or TtM-300 could be detected from one and two weeks PIE, respectively, and (3) IgG responses to some major components of both TtO and TtM-300, and TtM-30 were easily detected from four and five weeks PIE onwards, respectively. Both TtO and TtM (especially TtM-300) appeared to be highly useful for detection of antibody responses in experimentally infected rats. Due to the easiness in preparation of antigens, fully developed metacestodes may be the best candidate antigens for serodiagnosis. These results strongly suggest that both US image and antibody analyses using antigens from fully developed metacestodes are useful for detection of the early stage of cysticercosis in laboratory animal model.

Animals↗

PubMed1998

The alpha and eta isoforms of protein kinase C stimulate transcription of human involucrin gene.

Involucrin is one of the precursor proteins of the cornified cell envelope that is formed beneath the cell membrane during terminal differentiation of keratinocytes. 12-O-tetradecanoylphorbol-13-acetate (TPA), which is a potent protein kinase C (PKC) activator, induces terminal differentiation of keratinocytes. We previously demonstrated that involucrin promoter activity is stimulated by TPA in cultured fetal rat skin keratinocytes. PKC is a large family of proteins and keratinocytes containing five PKC isozymes: alpha, delta, epsilon, eta, and zeta. In order to determine the role of the PKC isozyme(s) on involucrin gene expression, we constructed the chloramphenicol acetyl transferase (CAT)-involucrin promoter expression vector by connecting the 5'-upstream region of the human involucrin gene containing the untranslated first exon to the CAT reporter gene. The CAT-involucrin promoter expression vector was transfected with various PKC isozyme expression vectors into SV40-transformed human keratinocytes (SVHK cells). Transfection of the CAT-involucrin promoter expression vector with PKC-alpha or PKC-eta expression vectors resulted in a significant increase in the TPA-dependent involucrin promoter activity. The PKC inhibitor, 1-(5-isoquinoline-sulfonyl)-2-methyl piperazine dihydrochloride, inhibited the promoter activity stimulated by TPA. Transfection of PKC-delta, -epsilon, and -zeta had no effect on the involucrin-promoter activity. Although the promoter activity was stimulated by transfection of PKC-gamma, TPA did not enhance the promoter activity in the PKC-gamma-transfected SVHK cells. Previously we showed three AP-1 binding sites (AP1-1, -2, and -3) on the involucrin promoter region. Both the basal and the TPA-stimulated involucrin promoter activities were suppressed by deleting the AP1-1 site (-119 to -113) that is the most proximal to the transcription start site. The deletion of AP1-2 (-297 to -303) or AP1-3 (-447 to -453) did not affect the involucrin promoter activity. Gel retardation analyses disclosed that TPA stimulated the specific DNA binding of the nuclear protein(s) of control, PKC-alpha, or PKC-eta-transfected SVHK cells, but not of PKC-gamma-transfected cells. Addition of anti-c-Jun and anti-c-Fos antibodies decreased the specific protein-DNA complex band with a concomitant appearance of supershifted bands. These results indicate that PKC, specifically PKC-alpha and PKC-eta, mediates the TPA-dependent activation of involucrin gene expression of SVHK cells. PKC-gamma, which is not present in keratinocytes, also induces involucrin gene expression in a TPA-independent manner, when introduced into SVHK cells.

Base Sequence↗

PubMed1998

Effects of oral antihyperglycemic agents on extracellular matrix synthesis by mesangial cells.

BACKGROUND: Increased expression of the glucose transporter GLUT1 in mesangial cells (MCs) markedly stimulates glucose transport and the formation of extracellular matrix (ECM), even when ambient glucose concentrations are low. Certain antihyperglycemic agents cause GLUT1 overexpression and increase glucose transport in various tissues. However, their effects on the kidney are unknown. Because diabetic glomerulosclerosis is characterized by the accumulation of mesangial matrix, was studied the effects of antihyperglycemic agents on matrix metabolism in MCs cultured either in 8 or 20 mM glucose. METHODS: Membrane-associated GLUT1 was measured by immunoblotting. The initial rate of glucose transport was determined according to the 2-deoxy-D[14C(U)]glucose uptake. Collagen metabolism was studied by metabolic radiolabeling with [14C]-proline. Fibronectin in the medium was measured by ELISA. GLUT1 mRNA was estimated by Northern analysis. RESULTS: The sulfonylurea tolazamide increased GLUT1 protein expression by 107 and 69% in 8 and 20 mM glucose-grown cells, respectively. However, GLUT1 mRNA levels remained unchanged. Transporter-dependent deoxyglucose uptake was increased by tolazamide up to 184% in a dose-dependent fashion and was evident at both glucose concentrations after three or five days of exposure to the drug. Tolazamide significantly stimulated transforming growth factor-beta 1 (TGF-beta 1) secretion and the total synthesis of collagen and collagen and fibronectin accumulation in the medium of MCs maintained in high or low glucose concentrations. The biguanide metformin did not alter GLUT1 expression, glucose transport, fibronectin formation, or collagen metabolism, except at high concentrations. CONCLUSION: Tolazamide markedly enhances ECM synthesis and accumulation in MCs probably by stimulating GLUT1 expression, glucose transport and TGF-beta 1 secretion, irrespective of the ambient glucose concentration. This effect was dose-dependent and minimally inducible by metformin.

Administration, Oral↗

PubMed1998

En bloc resection of the temporal bone by the lateral approach in carcinoma of the middle ear associated with skull base infiltration with reference to the resection of the petrous apex.

En bloc resection of the temporal bone was performed by the lateral approach on two patients with carcinoma of the middle ear, which was associated with destruction in the temporal bone and tumor infiltration of the cranial base. In one of the patients, the petrous apex was resected along with the temporal bone.En bloc resection on the temporal bone with the petrous apex is believed to be difficult because the internal carotid artery (ICA), cavernous sinus, and the brainstem are adjacent to each other in the petrous apex. However, the intra- and extracranial surgical procedures by this approach allow resection of the temporal bone ranging from the anterior part including the petrous apex to the posterior part including the mastoid process, the dura of the middle and posterior cranial fossae, and the sigmoid sinus, without exposure of the tumor. Special attention should be paid to the procedural points of surgery, such as, exposure of the petrous ICA, bleeding from the petrous sinus, and dural suturing in the vicinity of the apex. With regard to surgical indication, it is important to determine whether tumor infiltration is confined to the temporal bone and the dura of the middle and posterior fossa. If tumor infiltration into the petrous ICA, the dominant side of sigmoid sinus and/or the inferior cranial nerve is observed, then indication for surgery should be determined in a more critical manner.

Journal Article↗

PubMed1998

Effect of night exercise on the following partially deprived sleep.

Six trained male athletes (aged 24.3+/-2.9 years) performed cycling exercise from 23.00 to 23.50 h. From 00.30 to 07.00 h, the subjects followed a schedule that consisted of 30 min trying to fall asleep in bed and 60 min of being awake outside the bedroom. The control experiment was conducted without exercise under the same time schedule. An increase in rectal temperature induced by exercise was 1.9+/-0.4. After exercise, prolongation of sleep onset latency was observed only in the sleep period fron 00.30 to 01.00 h compared with the control night. Time spent in slow wave sleep throughout the night was significantly longer after exercise.

Adult↗

PubMed1998

Identification of a translation initiation factor 3 (eIF3) core complex, conserved in yeast and mammals, that interacts with eIF5.

Only five of the nine subunits of human eukaryotic translation initiation factor 3 (eIF3) have recognizable homologs encoded in the Saccharomyces cerevisiae genome, and only two of these (Prt1p and Tif34p) were identified previously as subunits of yeast eIF3. We purified a polyhistidine-tagged form of Prt1p (His-Prt1p) by Ni2+ affinity and gel filtration chromatography and obtained a complex of approximately 600 kDa composed of six polypeptides whose copurification was completely dependent on the polyhistidine tag on His-Prt1p. All five polypeptides associated with His-Prt1p were identified by mass spectrometry, and four were found to be the other putative homologs of human eIF3 subunits encoded in S. cerevisiae: YBR079c/Tif32p, Nip1p, Tif34p, and YDR429c/Tif35p. The fifth Prt1p-associated protein was eIF5, an initiation factor not previously known to interact with eIF3. The purified complex could rescue Met-tRNAiMet binding to 40S ribosomes in defective extracts from a prt1 mutant or extracts from which Nip1p had been depleted, indicating that it possesses a known biochemical activity of eIF3. These findings suggest that Tif32p, Nip1p, Prt1p, Tif34p, and Tif35p comprise an eIF3 core complex, conserved between yeast and mammals, that stably interacts with eIF5. Nip1p bound to eIF5 in yeast two-hybrid and in vitro protein binding assays. Interestingly, Sui1p also interacts with Nip1p, and both eIF5 and Sui1p have been implicated in accurate recognition of the AUG start codon. Thus, eIF5 and Sui1p may be recruited to the 40S ribosomes through physical interactions with the Nip1p subunit of eIF3.

Animals↗

PubMed1998

Suppressive activity of the chloroform extract of Tripterygium wilfordii Hook f on effector T cell activation during Hymenolepis nana infection in mice.

The chloroform extract of Tripterygium wilfordii Hook f (TWH extract) administered into mice daily at doses of 80.0 to 200.0 micrograms/kg (but not 40.0 micrograms/kg) caused suppression of protective immunity to Hymenolepis nana when the extract was injected subcutaneously during the induction phase of protective immunity. Daily administration of 200.0 micrograms/kg TWH extract, during the course of larval development from challenge, also suppressed protective immunity. Inhibition of protective immunity was only observed in mice that received TWH extract for 6 days at a daily dose of 200.0 micrograms/kg and were challenged 24 h after the final injection. TWH extract did not inhibit formation of effector cells that mediate delayed type hypersensitivity (DTH) to H. nana egg antigen when the extract was administered subcutaneously at a dose of 200.0 micrograms/kg/day for 5 days before cell preparation. However, TWH extract did inhibit DTH effector cell activation when cells prepared from infected, PBS-injected mice were transferred into 200.0 micrograms/kg TWH extract-treated recipient mice. These results strongly indicate that TWH extract cannot inhibit the generation of effector cells but will suppress their function in vivo.

Animals↗