Biomedical subjects

K Asano

Publications and source records attributed to K Asano.

At least 73 records · Page 4Linked to original sources

PubMed2000

A multifactor complex of eukaryotic initiation factors, eIF1, eIF2, eIF3, eIF5, and initiator tRNA(Met) is an important translation initiation intermediate in vivo.

Translation initiation factor 2 (eIF2) bound to GTP transfers the initiator methionyl tRNA to the 40S ribosomal subunit. The eIF5 stimulates GTP hydrolysis by the eIF2/GTP/Met-tRNA(i)(Met) ternary complex on base-pairing between Met-tRNA(i)(Met) and the start codon. The eIF2, eIF5, and eIF1 all have been implicated in stringent selection of AUG as the start codon. The eIF3 binds to the 40S ribosome and promotes recruitment of the ternary complex; however, physical contact between eIF3 and eIF2 has not been observed. We show that yeast eIF5 can bridge interaction in vitro between eIF3 and eIF2 by binding simultaneously to the amino terminus of eIF3 subunit NIP1 and the amino-terminal half of eIF2beta, dependent on a conserved bipartite motif in the carboxyl terminus of eIF5. Additionally, the amino terminus of NIP1 can bind concurrently to eIF5 and eIF1. These findings suggest the occurrence of an eIF3/eIF1/eIF5/eIF2 multifactor complex, which was observed in cell extracts free of 40S ribosomes and found to contain stoichiometric amounts of tRNA(i)(Met). The multifactor complex was disrupted by the tif5-7A mutation in the bipartite motif of eIF5. Importantly, the tif5-7A mutant is temperature sensitive and displayed a substantial reduction in translation initiation at the restrictive temperature. We propose that the multifactor complex is an important intermediate in translation initiation in vivo.

Binding Sites↗

PubMed2000

Isolation and characterization of pollen coat proteins of Brassica campestris that interact with S locus-related glycoprotein 1 involved in pollen-stigma adhesion.

Adhesion of pollen grains to the stigmatic surface is a critical step during sexual reproduction in plants. In Brassica, S locus-related glycoprotein 1 (SLR1), a stigma-specific protein belonging to the S gene family of proteins, has been shown to be involved in this step. However, the identity of the interacting counterpart in pollen and the molecular mechanism of this interaction have not been determined. Using an optical biosensor immobilized with S gene family proteins, we detected strong SLR1-binding activity in pollen coat extracts of Brassica campestris. Two SLR1-binding proteins, named SLR1-BP1 and SLR1-BP2, were identified and purified by the combination of SLR1 affinity column chromatography and reverse-phase HPLC. Sequence analyses revealed that these two proteins (i) differ only in that a proline residue near the N terminus is hydroxylated in SLR1-BP1 but not in SLR1-BP2, and (ii) are members of the class A pollen coat protein (PCP) family, which includes PCP-A1, an SLG (S locus glycoprotein)-binding protein isolated from Brassica oleracea. Kinetic analysis showed that SLR1-BP1 and SLR1-BP2 specifically bound SLR1 with high affinity (K(d) = 5.6 and 4.4 nM, respectively). The SLR1-BP gene was specifically expressed in pollen at late stages of development, and its sequence is highly conserved in Brassica species with the A genome.

Amino Acid Sequence↗

PubMed2000

Structural analysis of late intermediate complex formed between plasmid ColIb-P9 Inc RNA and its target RNA. How does a single antisense RNA repress translation of two genes at different rates?

The antisense Inc RNA encoded by the IncIalpha ColIb-P9 plasmid replicon controls the translation of repZ encoding the replication initiator and its leader peptide repY at different rates with different mechanisms. The initial loop-loop base pairing between Inc RNA and the target in the repZ mRNA leader inhibits formation of a pseudoknot required for repZ translation. A subsequent base pairing at the 5' leader of Inc RNA blocks repY translation. To delineate the molecular basis for the differential control, we analyzed the intermediate complexes formed between RepZ mRNA and Inc RNA(54), a 5'-truncated Inc RNA derivative. We found that the initial base pairing at the loops transforms into a more stable intermediate complex by its propagation in both directions. The resulting extensive base pairing indicates that the inhibition of the pseudoknot formation is established at this stage. Furthermore, the region of extensive base pairing includes bases different in related plasmids showing different incompatibility. Thus, the observed extensive base pairing is important for determining the incompatibility of the low-copy-number plasmids. We discuss the evolution of replication control systems found in IncIalpha, IncB, and IncFII group plasmids.

5' Untranslated Regions↗

PubMed2000

Myocardial-directed overexpression of the human beta(1)-adrenergic receptor in transgenic mice.

The beta(1)-adrenergic receptor (AR) is the dominant subtype in non-failing and failing myocardium. beta(1)-AR signaling, by the endogenous neurotransmitter norepinephrine, is central to the regulation of myocardial contractility. In heart failure, the beta(1)-AR undergoes subtype-selective downregulation which may protect against the increased cardiac adrenergic drive associated with this pathophysiological state. To examine the hypothesis that chronically increased beta(1)-AR mediated signaling has adverse myocardial effects, transgenic mice overexpressing the human beta(1)-AR in a cardiac-selective context were produced, utilizing an alpha-myosin heavy chain (MHC) promoter. In these mice, beta(1)-AR protein abundance was approximately 24-46-fold (1-2 pmol/mg protein) that of wild-type mice. Histopathological examination of young (4 months old) and old (approximately 9 months old) transgenic mouse hearts consistently demonstrated large areas of interstitial replacement fibrosis, marked myocyte hypertrophy and myofibrilar disarray. In addition, increased expression of the pre-apoptotic marker, Bax, was observed coincident with regions of fibrosis accompanied by an increased apoptotic index, as measured by TUNEL assay. Older non-transgenic mice exhibited a slight tendency towards a decreased fractional shortening, whereas older beta(1)-AR transgenic mice had a marked reduction in fractional shortening (%FS approximately 30) as determined by echocardiography. Additionally, older beta(1)-AR transgenic mice had an increased left ventricular chamber size. In summary, cardiac-directed overexpression of the human beta(1)-AR in transgenic mice leads to a significant histopathological phenotype with no apparent functional consequence in younger mice and a variable degree of cardiac dysfunction in older animals. This model system may ultimately prove useful for investigating the biological basis of adrenergically-mediated myocardial damage in humans.

Animals↗

PubMed2000

Expression of cadherin and CSF dissemination in malignant astrocytic tumors.

Cadherins are Ca2+-dependent cell adhesion molecules that play an important role in tissue construction and morphogenesis in multicellular organisms. Because in recent years there have been reports of cadherin involvement in tumor metastasis, we conducted an immunostain for E-cadherin and N-cadherin monoclonal antibodies in paraffin-embedded surgical specimens of primary and recurrent lesions in 13 cases of glioblastoma and nine cases of anaplastic astrocytoma. No expression of E-cadherin was detected in the tumor cells. On the other hand, expression of N-cadherin was observed in malignant astrocytic tumor cells, but the N-cadherin positive rate tended to be less at the time of recurrence. Decreased expression of N-cadherin was detected at the time of recurrence in 11 of the 13 cases in the glioblastoma group. Cerebrospinal fluid (CSF ) dissemination and extracranial metastasis were observed in nine (81.8%) of these 11 patients. Therefore, we tried to analyze the clinical backgrounds and the N-cadherin positive rates by statistics. We concluded that decreased expression of N-cadherin at the time of recurrence correlates with dissemination in malignant astrocytic tumors.

Adult↗

PubMed2000

Cornified cell envelope formation is distinct from apoptosis in epidermal keratinocytes.

In order to maintain epidermal structural homeostasis, keratinocytes need to modulate their proliferation, differentiation, and cell death. Although terminal differentiation of keratinocytes is characterized by cornified cell envelope (CE) formation and one major mechanism of cell death is apoptosis, the precise relationship between these processes remains obscure. Using normal human cultured keratinocytes (NHK), we compared A23187-induced CE formation and ultraviolet B irradiation (UVB)-induced apoptosis. A23187 stimulated CE formation in 1 mM Ca(2+)-pretreated NHK cells. CE formation was detected by 1 h and the maximal induction was observed at 6 h. Morphological analysis using acridine orange staining revealed that UVB-irradiated NHK cells show distinctive round, homogeneous fragmented nuclear beads, a characteristic feature of apoptotic cells, while A23187-treated cells showed enlarged nuclei with weak chromatin staining, which is not typical of apoptosis. The UVB-irradiated NHK cells did not show CE formation. Caspase activation is a characteristic event during apoptosis. Although UVB irradiation increased caspase 3 activity, no increase in caspase 3 activity was detected during A23187-induced CE formation. Multiple nucleosome-sized fragments of DNA were observed in UVB-treated NHK cells, but not in A23187-treated NHK cells. FACS analyses using anti-annexin V antibody and propidium iodide (PI) showed that UVB irradiation induced both annexin V-positive and PI-negative early apoptotic cells and annexin V-positive and PI-positive late apoptotic cells. On the other hand, A23187-treated NHK cells showed only annexin V-negative and PI-positive non-apoptotic dying cells. Cell death assay revealed a significantly increased apoptotic cells in UVB-irradiated NHK cells, but not in A23187-treated NHK cells. UVB irradiated NHK cells showed increased cytosolic transglutaminase activity, while A23187-treated NHK cells showed increased membrane-associated transglutaminase activity. These results indicate that CE formation is distinct from apoptosis in epidermal keratinocytes.

Anti-Bacterial Agents↗

PubMed2000

Molecular cloning and high-level expression in Escherichia coli of fungal alpha-galactosidase from Absidia corymbifera IFO 8084.

A cDNA encoding the alpha-galactosidase of Absidia corymbifera IFO 8084 was cloned and sequenced. The cloned DNA has a single open-reading frame consisting of 2190 base pairs, and the deduced amino acid sequence revealed that the mature enzyme consisted of 730 amino acid residues with a molecular mass of 82,712 Da. The native structure of the alpha-galactosidase of A. corymbifera IFO 8084 was determined to be a tetramer. Comparison with amino acid sequences of other alpha-galactosidase showed high homology with sequences of members of family 36. An expression vector, pET32Trx/galalpha, was constructed by introducing the cDNA coding region into a thioredoxin fusion system, pET32-Ek/LIC. The resulting transformant, pET32Trx/galalpha, overproduced the active enzyme as a thioredoxin fused form in the host Escherichia coli. By using His-binding metal affinity chromatography, recombinant alpha-galactosidase was purified to homogeneity in a single step. The purified recombinant fusion alpha-galactosidase showed properties very similar to the native alpha-galactosidase from A. corymbifera IFO 8084.

Journal Article↗

PubMed2000

Microbial demetallization of crude oil: nickel protoporphyrin disodium as a model organo-metallic substrate.

A soil isolate designated as YA-1 strain was selected for its ability to degrade nickel protoporphyrin disodium (NiPPDS). The strain was capable of utilizing NiPPDS as the sole source of carbon. This strain, a gram-negative aerobic rod, was identified as Pseudomonas azelaica YA-1 based on the result of its 16S rRNA analysis. Product analyses by HPLC showed that this strain can decompose the porphyrin ring to which a metal ion is bound. However, the use of whole bacterial cells cannot result in extensive NiPPDS degradation; therefore, the YA-1 enzyme was extracted and purified. This NiPPDS-degrading enzyme named as protoporphyrinase was purified from P. azelaica YA-1 by ammonium sulfate fractionation and sequential chromatographies using DEAE Toyopearl 650 M, CM Toyopearl 650 M and Biogel P-60 columns, with a yield of 11.3% based on the enzyme activity and an overall purification of 498-fold. The molecular weight of this enzyme is estimated to be 39,000 Da by SDS-PAGE and 34,000 Da by gel filtration. The optimum pH and temperature for the enzyme were 7.0 and 30 degrees C, respectively. The activity was stable at pH 2.0-11.0 and at temperatures below 50 degrees C. The enzyme activity was inactivated by ferric chloride, potassium ferricyanide, ZnCl2 and CdCl2.

Journal Article↗

PubMed2000

A case of erythrokeratoderma variabilis without mutations in connexin 31.

Erythrokeratoderma (EK) variabilis is a heterogeneous group of diseases characterized by migratory erythematous patches and hyperkeratotic plaques. Mutations in connexin 31 have recently been found to underlie several cases of EK variabilis. We describe a Japanese girl with extensive lesions that appeared to be a form of EK variabilis, clinically resembling genodermatose en cocardes (Degos). Our patient had characteristic migratory rosette or target-like erythematous keratotic plaques with peripheral scaling in addition to relatively fixed keratotic plaques. Sequencing of the connexin 31 gene did not detect mutations. Skin biopsy showed parakeratotic hyperkeratosis with hypergranulosis. Immunohistochemically, suprabasal keratins, involucrin and profilaggrin were unequivocally expressed, while loricrin expression was greatly diminished and deiminated K1 was undetectable. Our results confirm aetiological heterogeneity in EK. The histological features suggest disruption of keratinocyte terminal differentiation at a very late stage.

Biopsy↗

PubMed2000

Squamous cell carcinoma of the renal pelvis with inferior vena caval extension.

BACKGROUND: We report here on a third case of squamous cell carcinoma (SCC) of the renal pelvis extending to the inferior vena cava. METHODS/RESULTS: A 48-year-old man was diagnosed with an advanced left renal pelvic tumor on computed tomography. He had undergone extracorporeal shock wave lithotripsy for left staghorn calculi 10 years ago. An inferior vena cavagram showed tumor thrombus extending to the inferior vena cava. Percutaneous left renal biopsy revealed SCC. The patient received three courses of combination chemotherapy with cisplatin, bleomycin and etoposide. However, 1 month after the last course of chemotherapy, he died of cancer progress. CONCLUSION: This is the third case of SCC of the renal pelvis extending to the inferior vena cava in the world.

Antineoplastic Combined Chemotherapy Protocols↗

PubMed2000

Suppressive effects of co-stimulatory molecule expressions on mouse splenocytes by anti-allergic agents in vitro.

The influence of anti-allergic drugs, epinastine hydrochloride (EP) and disodium cromoglycate (DSCG), on the co-stimulatory molecule expression was examined using in vitro cell culture technique. Spleen cells obtained from BALB/c mice 10 days after immunization with haemocyanin absorbed to aluminium hydroxide were cultured in the presence of 100.0 microg/ml haemocyanin and various concentrations of the agents. Low concentrations (<1.5 x 10(-4)M) of EP and DSCG did not influence spleen cell blastic activity induced by antigenic stimulation, whereas these agents caused significant inhibition of spleen cell activation when 2 x 10(-4) M of the agents were added to cell cultures. EP and DSCG also did not affect blastic activity of sensitized splenic T cells by anti-CD3 monoclonal antibody stimulation even when these cells were cultured in the presence of 2 x 10(-4) M of the agents. We next examined the influence of EP and DSCG on the expression of co-stimulatory molecules on spleen cells in response to antigenic stimulation. Sensitized spleen cells were cultured in the presence of 2 x 10(-4)M of the agents and the expression of molecules were examined by flow cytometer 24h later. EP and DSCG suppressed the expression of costimulatory molecules, CD40 and CD80, but not CD86, on splenic B cells which were enhanced by antigenic stimulation in vitro.

Animals↗

PubMed2000

The inhibitory effect of anti-allergic agent suplatast tosilate (IPD-1151T) on methacholine- and allergen-induced bronchoconstriction in sensitized mice. asakazu@med.showa-u.dc.jp.

The influence of an anti-allergic agent, suplatast tosilate (IPD-1151T; (+/-)-[2-[4-(3-ethoxy-2-hydroxypropoxy)phenyl-carbamoyl]-ethyl] dimethylsulfonium p-toluenesulfonate) on allergic bronchoconstriction induced by allergen and methacholine (MCh) were examined in mice. BALB/c mice were sensitized by intraperitoneal injection of dinitrophenylated-keyhole limpet hemocyanin (DNP-KLH) mixed with A1(OH)3 (DNP-KLH). IPD-1151T was administered orally once a day for either 5 or 14 days in doses of 10, 30 or 100 mg/kg. Bronchoconstriction was measured 24h after the final drug administration. IPD-1151T inhibited both antigen- and MCh-mediated bronchoconstriction in actively sensitized mice. The inhibition induced was closely related to the dose and frequency of oral administration of the agent. We also examined the effect of IPD-1151T on IgE production in response to DNP-KLH immunization. IPD-1151T inhibited dose-dependently both total and specific IgE concentrations in serum prepared from mice 15 days after immunization. These results strongly indicate that IPD-1151T inhibits IgE production in vivo and results in attenuating effect on bronchoconstriction.

Allergens↗

PubMed2000

Suppressive activity of a macrolide antibiotic, roxithromycin on co-stimulatory molecule expression on mouse splenocytes in vivo.

The influence of roxithromycin (RXM) on the expression of co-stimulatory molecules, CD40, CD80 and CD86, was examined in vivo. When BALB/c mice were immunized intraperitoneally with two doses of dinitrophenylated ovalbumin (DNP-OVA) at 1 week intervals, intraperitoneal administration of RXM at 250 microg/kg once a day for 14 days strongly suppressed IgE contents in sera obtained from mice 22 days after the first immunization. In addition, RXM treatment of mice suppressed endogenous IL-4 contents in aqueous spleen extracts, which were enhanced by DNP-OVA immunization. We next examined the influence of RXM on co-stimulatory molecule expression on splenic lymphocytes. RXM treatment of the immunized mice caused suppression of CD40 expression, but this treatment did not affect CD80 and CD86 expression.

Animals↗

PubMed2000

Expression of estrogen receptor alpha and beta mRNAs in prostate cancers treated with leuprorelin acetate.

OBJECTIVE: The discovery of a novel estrogen receptor (ER), ER-beta, has given rise to new possibilities regarding estrogen's roles in the prostate. Although ER-beta is reported to be expressed preferentially in the rat prostate, its expression in the human prostate and relationship to cancer development has not been investigated. Thus the purpose of the study was to examine mRNA levels of ER-alpha and ER-beta in benign prostatic hyperplasia and prostate carcinoma. METHODS: Samples of 15 prostate cancers obtained at radical prostatectomy were examined. All the patients had been maintained on androgen withdrawal therapy for at least 3 months. ER-alpha and ER-beta mRNAs were measured with a competitive PCR technique. RESULTS: Both ER-alpha and ER-beta mRNAs were detected in all of the prostate cancer tissues examined, as well as in PC3 and LNCap cells, although the levels varied among specimens. Interestingly, both types were significantly decreased in cases with lymph node metastasis. However, there was no correlation between ER mRNA levels and any other clinicopathological parameters. CONCLUSIONS: (1) Both ER-alpha and ER-beta mRNAs are expressed in prostate cancer and (2) expression of ER mRNA may not be related to cancer progression but may be negatively correlated with metastasis.

Aged↗

PubMed2000

Thymoma with pemphigus foliaceus.

A 75-year-old Japanese woman was referred to us because of an anterior mediastinal mass. Crusts and shallow erosions developed 10 months earlier on her upper chest, back, and scalp. Pemphigus foliaceus was diagnosed based on histological examination of skin biopsy specimens and positivity for serum anti-desmoglein 1 antibody by enzyme-linked immunosorbent assay. Neurological examination and electromyography ruled out myasthenia gravis. Total thymectomy was performed, and the postoperative pathology studies showed mixed lymphoepithelial thymoma. One year after the resection, the eruption and alopecia improved and the serum anti-desmoglein 1 antibody titer decreased, suggesting a beneficial effect of thymectomy on thymoma-related pemphigus.

Aged↗

PubMed2000

An unusual case of mediastinal lymphadenopathy caused by amyloidosis.

A 71-year-old Japanese female Nagasaki-atomic-bomb survivor was admitted for evaluation of a mediastinal mass. She was infected with human T-cell leukemia virus type I. Histological examination of the biopsy specimen, obtained thoracoscopically from the mass, revealed amyloid lymphadenopathy confirmed by Congo-red staining and electron-microscopic examination. Amyloid deposits and the serum monoclonal peak consisted of immunoglobulin lambda light chains. No atypical cells were detected in bone marrow. The case was diagnosed as an unusual amyloidosis affecting the mediastinal lymph node. No other sites were found to be affected by amyloidosis, although systemic involvement could not be conclusively ruled out.

Aged↗

PubMed2000

Malignant melanoma arising from the sphenoidal sinus--case report.

Malignant melanomas arising from the sella turcica or sphenoidal sinus with bilateral invasion of the base of the skull or cavernous sinus are extremely rare. Whether the sella turcica or sphenoidal sinus is the site of origin is difficult to determine based on neuroradiological findings. An 83-year-old Japanese female presented with headache as the initial symptom. She suffered rapid progression of bilateral obstruction of the nasal cavity, left nasal bleeding, and bilateral visual field defects. The preoperative diagnosis was pituitary adenoma, metastatic tumor, or malignant paranasal tumor. Biopsy was performed. The histological diagnosis was malignant melanoma. Postoperatively, the tumor progressed rapidly. She suffered several cranial nerve pareses and hypopituitarism. She died within 6 months. Tumors arising from the sphenoidal sinus cause obstruction of the nasal cavity or nasal bleeding first, and then cause cranial nerve pareses by invasion of the cavernous sinus. This sequence of clinical manifestations can be attributed to the anatomical relationships between the sphenoidal sinus, nasal cavity, and cavernous sinus. Differential diagnosis of the origin in the sella turcica or sphenoidal sinus appears to be relatively easy based on further observation of the clinical course and symptoms.

Aged↗

PubMed2000

Subepicranial varix mimicking sinus pericranii: usefulness of three-dimensional computed tomography angiography and bone window computed tomography--case report.

A 16-year-old female presented with a rare case of subepicranial varix in the left temporal area manifesting as a soft mass in the left temporal area when she laid down in the left lateral position. Bulging of the mass was observed when intracranial venous pressure was raised by the Valsalva maneuver, the left lateral position, or the prone position. Bone window computed tomography (CT) revealed a tiny hole, 1 mm in diameter, in the outer bone table. Three-dimensional CT (3D-CT) angiography clearly visualized a mass with a diameter of approximately 10 mm connected to the diploic vein. The mass was totally resected by operation. Venous bleeding was observed from the tiny hole. Histological examination revealed a venous lesion mimicking sinus pericranii and containing endothelial cells. No communication with the intracranial venous sinuses was identified, so the diagnosis was subepicranial varix. Radiological examination by direct injection of contrast medium is usually performed to identify subepicranial varix, but 3D-CT angiography is a non-invasive preoperative examination that can visualize this small venous lesion. Adjustment of the CT acquisition conditions may allow 3D-CT angiography to identify sinus pericranii in the future.

Adolescent↗