Biomedical subjects

Y Asada

Publications and source records attributed to Y Asada.

At least 55 records · Page 3Linked to original sources

PubMed2000

Filamentous fungus Aspergillus oryzae has two types of alpha-1,2-mannosidases, one of which is a microsomal enzyme that removes a single mannose residue from Man9GlcNAc2.

alpha-Mannosidase activities towards high-mannose oligosaccharides were examined with a detergent-solubilized microsomal preparation from a filamentous fungus, Aspergillus oryzae. In the enzymatic reaction, the pyridylaminated substrate Man(9)GlcNAc(2)-PA was trimmed to Man(8)GlcNAc(2)-PA which lacked one alpha-1,2-mannose residue at the nonreducing terminus of the middle branch (Man8B isomer), and this mannooligosaccharide remained predominant through the overall reaction. Trimming was optimal at pH 7.0 in PIPES buffer in the presence of calcium ion and kifunensine was inhibitory with IC(50) below 0.1 microM. These results suggest that the activity is the same type as was previously observed with human and yeast endoplasmic reticulum (ER) alpha-mannosidases. Considering these results together with previous data on a fungal alpha-1,2-mannosidase that trimmed Man(9)GlcNAc(2) to Man(5)GlcNAc(2) (Ichishima, E., et al. (1999) Biochem J, 339: 589-597), the filamentous fungi appear to have two types of alpha-1,2-mannosidases, each of which acts differently on N-linked mannooligosaccharides.

Aspergillus oryzae↗

PubMed2000

Radiographic evaluation of bioactive glass-ceramic grafts in postero-lateral lumbar fusion.

STUDY DESIGN: Follow-up study of bioactive glass-ceramic graft for postero-lateral fusion (PLF) in the lumbar spine was performed using plain radiography. OBJECTIVES: To investigate the fusion state of the porous stick type of bioactive glass-ceramic which has been used in PLF in the lumbar spine, by plain radiography, and to evaluate the usefulness of this technique. METHODS: Fourteen patients who underwent PLF using apatite and wollastonite-containing glass-ceramic (A-W. GC) were followed-up for more than 1 year and 6 months by plain radiography. RESULTS: Six patients who were followed up for more than 2 years were considered to have obtained subtotal or total fusion. CONCLUSION: PLF using A-W. GC mixed with autologous grafted bone can preserve bone stock without the need to harvest a bone graft from the iliac crest and will be useful for PLF in the lumbar spine.

Bone Transplantation↗

PubMed2000

Brain surface ependymoma.

A case of brain surface ependymoma is reported here. A 41-year-old woman presented with weakness of the right upper limb. Magnetic resonance imaging revealed a left fronto-parietal cystic tumor with a calcified mural nodule. Total removal of the tumor was performed. This tumor was located within the surface portion of the fronto-parietal parenchyma and was sharply demarcated from the surrounding brain tissue, and there was no continuity with the ventricles. Histological examination of this tumor showed monotonous proliferation of tumor cells with moderate cellularity and occasional mitoses, forming true ependymal rosettes and perivascular pseudorosettes with fibrillary background. A clear cell component resembling oligodendroglioma was partly noted. The tumor cells showed positive immunoreaction for glial fibrillary acid protein and vimentin.

Adult↗

PubMed2000

Neuroblastoma cell lines showing smooth muscle cell phenotypes.

Neuroblastoma is a tumor that is derived from the neural crest. Recent studies demonstrated that several human neuroblastoma cell lines exhibit at least three morphologic types: neuroblastic (N)-type, substrate-adhesive (S)-type and intermediate (I)-type cells. However, the origin of the S-type cells has not been clearly identified. In this study, the expressions of smooth muscle-specific proteins (desmin, alpha-smooth muscle actin, basic calponin and the smooth muscle myosin heavy-chain isoforms of SM1 and SM2) in three parent and four cloned neuroblastoma cell lines, composed of S-type cells, were examined by indirect immunofluorescence, Western blot and/or by reverse transcription-polymerase chain reaction (RT-PCR). Desmin was found in two of the seven cell lines, and alpha-smooth muscle actin and basic calponin were detected in all of seven of the cell lines. In three parent cell lines and one cloned cell line composed of N-type cells, none of three smooth muscle-specific proteins were detected. In smooth muscle myosin heavy-chain isoforms, SM1 was detected in two parent cell lines composed of S-type cells (MP-N-MS and KP-N-YS) by immunofluorescence, Western blot and/or by RT-PCR, whereas the SM2 isoform was detected in one parent cell line (MP-N-MS) by RT-PCR. These findings indicate that S-type cells have either the immature or mature smooth muscle cell phenotype, and neural crest cells very likely have the ability of to differentiate into smooth muscle cells in the human system.

Blotting, Western↗

PubMed2000

Postoperative hyponatremia in a patient with ACTH-producing Merkel cell carcinoma.

Merkel cell carcinoma is characterized by specific neuroendocrine features and the expression of several neuropeptides. We report a case of Merkel cell carcinoma with post-surgical hyponatremia in an 85-year-old Japanese woman. A tumor on the left cheek histopathologically showed the characteristics of Merkel cell carcinoma together with Bowen's disease. Although an increased level of ACTH was found both in the tumor and in the peripheral blood, the postoperative hyponatremia in our patient seems more likely to have been caused by the stress of the operation and indapamide, considering that the ACTH level in the tumor was much lower than those in other ectopic ACTH-producing tumors in previous reports.

Adrenocorticotropic Hormone↗

PubMed2000

A case of pencil core granuloma with an unusual temporal profile.

The patient is a 47-year-old female with a bluish tumor resembling malignant melanoma at the macroscopic level on the medial aspect of her left big toe. The patient had crushed a pencil with this toe about 30 years previously and, since then, a bluish lesion had been present. About 15 years ago, the lesion had suddenly increased in size over the course of a few months. Subsequently, the size of the lesion had not changed noticeably. Ultrasonography, but not magnetic resonance imaging was a helpful preoperative examination to distinguish the lesion from malignant melanoma. The excised lesion contained a piece of material that resembled pencil lead and bluish mud. X-ray microanalysis of the lead-like material revealed that its composition was similar to that of pencil lead. Histologic examination showed features of foreign-body reaction, except for necrotic change and few histiocytes.

Female↗

PubMed2000

Phosphotransacetylase as a key factor in biological production of polyhydroxybutyrate.

Phosphotransacetylase (Pta) catalyzes the reversible conversion of acetyl-coenzyme A (CoA) to acetyl phosphate. Polyhydroxybutyrate (PHB) synthase and accumulation were compared between a Pta-deficient mutant and the wild-type Escherichia coli, which were transformed with pAE100, coding for 3-ketothiolase, NADPH-dependent acetoacetyl-CoA reductase, and PHB synthase from Ralstonia eutropha. During the growth period, PHB synthase activity in the Pta-deficient mutant was lower than that in the wild type. PHB accumulation in the Pta-deficient mutant, however, was higher than that in wild-type cells grown in Luria-Bertani (LB) medium containing 1% glucose (high C:N ratio). The Pta-deficient mutant showed PHB accumulation even in LB medium (low C:N ratio), whereas wild-type cells showed no PHB accumulation. These data suggest the activation of PHB synthase by acetyl phosphate that is synthesized by Pta. A decrease in Pta activity probably causes some increase in acetyl-CoA as substrate for the PHB synthesis pathway, resulting in increased PHB accumulation.

Acyltransferases↗

PubMed2000

Effect of light/dark cycle on bacterial hydrogen production by Rhodobacter sphaeroides RV. From hour to second range.

Hydrogen production by photosynthetic bacteria provides an efficient energy conversion method under low light intensity. However, under strong illumination, such as midday sunlight, the efficiency drops. This prevents the method from being applied industrially. To overcome this problem, we examined a method to thin out the excessive illumination. Light was given intermittently to reduce the total energy flux. The on/off ratio was set at 1/1 throughout the study, so that the time average of the light energy flux became half the continuous illumination. By keeping the time-average light flux constant (0.6 kW.m-2), the effects of the cycle period were examined in the range of hours to seconds. The hydrogen production rate was greatly affected by the cycle period, but cell growth and substrate consumption rates remained almost constant. The 30-min light/dark cycle (30 min on and 30 min off) provided the highest rate of hydrogen production (22 L.m-2.24 h-1). At the shorter cycles, the rate decreased except that there was a suboptimum at about 40 s. Under excessive light intensity (1.2 kW.m-2), the light-to-hydrogen conversion efficiency was greatly enhanced. The hydrogen production rate during the 30-min cycle was twice as high as during a 12-h cycle under the same conditions.

Activity Cycles↗

PubMed2000

Polyhydroxybutyrate production from carbon dioxide by cyanobacteria.

Genetic characterization and enhancement of polyhydroxybutyrate (PHB) accumulation in cyanobacteria were investigated for efficient PHB production from CO2. The genome DNAs in the PHB-accumulating strains Synechococcus sp. MA19 and Spirulina platensis NIES46 retained the highly homologous region to phaC of Synechocystis PCC6803, whereas low homology was detected in the nonaccumulating strains Synechococcus sp. PCC7942 and Anabaena cylindrica NIES19. Synechococcus sp. MA19, which accumulates PHB up to 30% of dry cell weight from CO2 as the sole carbon source, was mutated by insertion of transposon Tn5 to enhance the PHB accumulation. Genetic and physiological analysis of the mutant indicated that decreased phosphotransacetylase activity could trigger an increase of acetyl coenzyme A leading to enhancement of PHB accumulation. PHB synthase in Synechococcus sp. MA19 was probably attached to thylakoid membrane since PHB granules were associated with pigments. A genetically engineered cyanobacteria retaining soluble PHB synthase from Ralstonia eutropha accumulated pigment-free PHB granules, which is an advantage for the purification of PHB.

Acyltransferases↗

PubMed2000

Collaborative work to evaluate toxicity on male reproductive organs by repeated dose studies in rats 4). Fadrozole hydrochloride: an oral 2/4-week male reproductive organ toxicity study.

Doses of 0, 30 and 60 mg/kg/day of fadrozole hydrochloride (Afema: non-steroidal aromatase inhibitor, antitumor agent) were given perorally by gavage to HanIbm WIST male rats from 6 or 8 weeks of age for 2 weeks, and from 6 weeks of age for 4 weeks. In all treatment groups, reduced weights of seminal vesicle, prostate and epididymis, and degeneration/necrosis of the pachytene spermatocytes in stages VII or VIII seminiferous tubules, were dose-relatedly observed. Effects could also be assessed quantitatively by staging analysis with the result of a reduction in the numbers of stage VII pachytene spermatocytes at 30 and 60 mg/kg/day. Epididymal sperm examination revealed no treatment-related changes in any groups. The effects of 4-week treatment on male reproductive organs were similar to those of 2-week treatment at the same dose levels, except for the weights of seminal vesicle and prostate, which were more reduced by 4-week treatment than by 2-week treatment. There was no notable difference in detectability of toxicity in male reproductive organs between 2-week treatment from 6 weeks of age and 2-week treatment from 8 weeks of age. It was concluded that the changes observed in the rat male reproductive organs following 4 weeks of treatment with fadrozole hydrochloride could be detected also with 2 weeks of treatment.

Administration, Oral↗

PubMed2000

Malignant colonic obstruction due to extrinsic tumor: palliative treatment with a self-expanding nitinol stent.

OBJECTIVE: The purpose of this study was to evaluate the usefulness of self-expanding nitinol stents for palliative treatment of malignant colorectal obstruction caused by unresectable extrinsic tumor, colorectal metastasis, or peritoneal seeding. SUBJECTS AND METHODS: One covered stent and 10 uncovered stents were deployed in eight patients with colorectal obstruction due to extrinsic tumor under fluoroscopic guidance. The sites of obstruction were located in the rectum (n = 5), in the rectosigmoid colon (n = 2), and from the transverse colon to the descending colon (n = 1). Clinical usefulness and complications were analyzed. RESULTS: Stents were placed successfully in all patients. Minor modifications of the delivery system were required in the tortuous rectosigmoid and lower rectum strictures. Symptoms of obstruction were initially resolved in all but one patient. In that patient, the presence of other points of obstruction was suspected. Bowel obstruction recurred in two patients: one obstruction was due to migration of a covered stent 4 days after the procedure, and the other obstruction was due to peritoneal seeding 33 days after the procedure. Both required colostomy or ileostomy. All patients died 12-111 days after stent placement (mean, 56 days). In five patients (63%), colonic obstruction was palliated by placing a stent until the patients' death between 39 and 111 days after stent placement (mean, 62 days). Six complications occurred in four patients and included stent migration (n = 1), anal bleeding (n = 2), anal pain that required analgesia (n = 1), and fever (n = 2). CONCLUSION; This self-expandable nitinol stent adequately palliated 63% of patients with colonic obstruction due to extrinsic tumor in this small series. Patient selection is very important to the success of this treatment.

Alloys↗

PubMed2000

Neurocutaneous vascular hamartomas mimicking Cobb syndrome. Case report.

The authors report the rare case of a patient with neurocutaneous vascular hamartomas mimicking Cobb syndrome. An 8-year-old boy was admitted to the authors' hospital with progressive urinary disturbance and upper back pain. Multiple skin nevi had been noted at the child's birth. Radiological examination revealed multiple cavernous angiomas in the spinal cord in the same metamere in which the skin nevi had been observed and also in the left cerebral hemisphere. His symptoms gradually improved without surgical intervention. Four years later he was readmitted because of a cerebral hemorrhage involving the left cerebral peduncle. Nonsurgical treatment was chosen because his symptoms promptly improved. To the best of the authors' knowledge, this is the first case of multiple cavernous angiomas in the brain and spinal cord associated with skin nevi. The authors discuss this clinical entity and the significance of the disease.

Back Pain↗

PubMed2000

Coronary atherosclerosis in youths in Kyushu Island, Japan: histological findings and stenosis.

We histologically examined the coronary arteries of 52 autopsied cases of the youths (3 to 39 years of age, mean 28.5 years) in Kyushu island, Japan, without clinical events of coronary artery diseases. The coronary artery specimens were taken from the proximal portions of the right coronary artery (Seg. 1), the left anterior descending artery (Seg. 6), and the macroscopically most stenotic region (ST). Atherosclerotic lesions were histologically classified into four types: concentric fibrous, eccentric fibrous, concentric lipid rich, or eccentric lipid-rich type. The degrees of stenosis (< 25%, 25-50%, 50 75%, > 75%) were morphometrically evaluated. The majority of coronary arteries with under 50% stenosis were of the concentric fibrous type. Lipid-rich types of coronary atherosclerosis increased in the coronary arteries with over 50% stenosis and were observed in the Seg. 6 and ST, while 70% of Seg. 1 lesions with over 50% stenosis were of a fibrous type. Serum cholesterol levels of patients with a lipid rich type of coronary atherosclerosis were significantly higher than those with a fibrous type. These results suggested that the early stage of coronary atherosclerosis in Japanese youths is mainly of a concentric fibrous type, which later develops to a lipid rich type. Hypercholesterolemia would promote the progression of atherosclerosis.

Adolescent↗

PubMed2000

A new-type titanium intervertebral spacer and its insertion device used in posterior lumbar interbody fusion.

We have recently developed a new-type trapezoid mesh cage (TPM cage) together with an insertion device, which for use as a new titanium mesh intervertebral spacer in posterior lumbar interbody fusion (PLIF). The TPM cage has sufficient mechanical strength, a large contact area that gives good long-term stability, and preserves the initial disc height to provide good balance. The insertion device for the TPM cage is useful not only for handling the implant but also for controlling the implant insertion direction. The TPM cage and its insertion device are promising for use in PLIF.

Biocompatible Materials↗

PubMed1999

Dynamic Ca2+ signalling in rat arterial smooth muscle cells under the control of local renin-angiotensin system.

1. We visualized the changes in intracellular Ca2+ concentration ([Ca2+]i), using fluo-3 as an indicator, in individual smooth muscle cells within intact rat tail artery preparations. 2. On average in about 45 % of the vascular smooth muscle cells we found spontaneous Ca2+ waves and oscillations ( approximately 0.13 Hz), which we refer to here as Ca2+ ripples because the peak amplitude of [Ca2+]i was about one-seventh of that of Ca2+ oscillations evoked by noradrenaline. 3. We also found another pattern of spontaneous Ca2+ transients often in groups of two to three cells. They were rarely observed and are referred to as Ca2+ flashes because their peak amplitude was nearly twice as large as that in noradrenaline-evoked responses. 4. Sympathetic nerve activity was not considered responsible for the Ca2+ ripples, and they were abolished by inhibitors of either the Ca2+ pump in the sarcoplasmic reticulum (cyclopiazonic acid) or phospholipase C (U-73122). 5. Both angiotensin antagonists ([Sar1,Ile8]-angiotensin II and losartan) and an angiotensin converting enzyme inhibitor (captopril) inhibited the Ca2+ ripples. 6. The extracellular Ca2+-dependent tension borne by unstimulated arterial rings was reduced by the angiotensin antagonist by approximately 50 %. 7. These results indicate that the Ca2+ ripples are generated via inositol 1,4, 5-trisphosphate-induced Ca2+ release from the intracellular Ca2+ stores in response to locally produced angiotensin II, which contributes to the maintenance of vascular tone.

1-Sarcosine-8-Isoleucine Angiotensin II↗

PubMed1999

Altered cochlear fibrocytes in a mouse model of DFN3 nonsyndromic deafness.

DFN3, an X chromosome-linked nonsyndromic mixed deafness, is caused by mutations in the BRN-4 gene, which encodes a POU transcription factor. Brn-4-deficient mice were created and found to exhibit profound deafness. No gross morphological changes were observed in the conductive ossicles or cochlea, although there was a dramatic reduction in endocochlear potential. Electron microscopy revealed severe ultrastructural alterations in cochlear spiral ligament fibrocytes. The findings suggest that these fibrocytes, which are mesenchymal in origin and for which a role in potassium ion homeostasis has been postulated, may play a critical role in auditory function.

Animals↗

PubMed1999

Inhibition of Vpr-induced cell cycle abnormality by quercetin: a novel strategy for searching compounds targeting Vpr.

Vpr, an accessory gene product of HIV-1 which induces cell cycle abnormality leading to the increased HIV replication, is supposed to be a possible target for anti-AIDS drugs. We recently established a cell line (MIT-23) in which Vpr-induced cell cycle perturbation could be manipulated by a tetracycline promoter. Here, we screened anti-Vpr activity in 27 kinds of herb drugs using MIT-23 cells. One of the extracts prepared from Houttuyniae herba showed an inhibitory activity. Quercetin (QCT), a compound of this crude drug, efficiently inhibited Vpr function without affecting its expression. Furthermore, data suggested that Vpr-induced transcription from HIV-LTR was considerably abrogated by QCT. These data indicate that QCT, a flavonoid previously reported to inhibit HIV replication, also targets Vpr, implicating that MIT-23 cell provides a novel strategy for screening compounds possessing anti-Vpr activity which would be in turn utilized for clarifying the mechanism of Vpr function.

Anti-HIV Agents↗

PubMed1999

Adenovirus-mediated local expression of human tissue factor pathway inhibitor eliminates shear stress-induced recurrent thrombosis in the injured carotid artery of the rabbit.

The main cause of acute coronary syndrome may be recurrent thrombosis, which is initiated by the activation of the extrinsic coagulation pathway. Tissue factor (TF) pathway inhibitor (TFPI) efficiently inhibits an early step in this pathway by the formation of a complex with factor VIIa, TF, and factor Xa. We determined whether local TFPI gene transfer can inhibit thrombosis in an injured artery without inducing systemic side effects. Balloon-injured rabbit carotid arteries were infected with an adenoviral vector that expressed either human TFPI (AdCATFPI) or bacterial beta-galactosidase (AdCALacZ). Two to 6 days after gene transfer, thrombosis was induced by the production of constant stenosis of the artery, and blood flow was measured continuously with an electromagnetic flow probe. A cyclic flow variation, which is thought to reflect the recurrent formation and dislodgment of mural thrombi, was observed in all AdCALacZ-infected arteries as well as in saline-infused arteries. In contrast, no cyclic flow variation was detectable in AdCATFPI-transfected arteries, even in the presence of epinephrine (1 microg. kg-1. min-1 infusion). Prothrombin time, activated partial thromboplastin time, and the ex vivo platelet aggregation induced by either adenosine diphosphate or collagen were unaltered in AdCATFPI-infected rabbits. We found that in vivo TFPI gene transfer into an injured artery completely inhibits the recurrent thrombosis induced by shear stress even in the presence of catecholamine, without affecting systemic coagulation status. Adenovirus-mediated local expression of TFPI may have the potential for the treatment of human thrombosis.

Adenoviridae↗