Search PubMed⌕ Search

Biomedical subjects

T Imanaka

Publications and source records attributed to T Imanaka.

At least 145 records · Page 8Linked to original sources
PubMed1996

Salazosulfapyridine-induced angioimmunoblastic lymphadenopathy.

A 20-year-old man with ulcerative colitis was admitted because of fever, eruption and lymphadenopathy. He had started taking salazosulfapyridine one month previously. Lymph node biopsy revealed angioimmunoblastic lymphadenopathy. Autoantibody titers were all negative, and viral antibody titers were not increased retrospectively. Rearrangement of T-cell receptor beta and chromosomal aberration were not seen on the lymph node. This case is considered not to be a peripheral T-cell lymphoma but rather salazosulfapyridine-induced angioimmunoblastic lymphadenopathy (AIL), which is the second case in English language literature.

Adult↗
PubMed1996

Characterization of vitronectins in atherosclerotic lesions.

Vitronectin is one of the major extracellular matrix proteins that accumulates in atherosclerotic lesions. A monoclonal antibody (EMR1a/212D) specifically stained the extracellular regions in thickened intima which colocalized well with lipid deposition. The antigenic glycoprotein with a molecular weight of 66KDa was revealed to be rabbit vitronectin. When homogenates of WHHL rabbit atheroma were subjected to immunoblot analysis using EMR1a/212D, four molecules with molecular weight 66, 56, 50 and 47KDa were detected. To confirm whether these smaller immunopositive bands were derived from mature vitronectin, another monoclonal antibody (EMR1b/244H) recognizing the polypeptide region of vitronectin was prepared. All four molecules were detected by EMR1b/244H as well as by EMR1a/212D. Two smaller vitronectins (56KDa and 50KDa) were found in atherosclerotic lesions and increased markedly during the development of atherosclerosis. On the other hand, the vitronectin detected in normal rabbit aorta was mainly of the mature type, while 56KDa and 47KDa forms were not detected. The total amount of the four vitronectins in atherosclerotic lesions was 38.5 +/- 5.0 ng/mg wet weight tissue, a value approximately 9.5 fold higher than that found in normal aorta. In conclusions, we found massive accumulation of these vitronectins concomitant with atherosclerotic development in rabbit aorta.

Animals↗
PubMed1996

Sensitive detection of oxidatively modified low density lipoprotein using a monoclonal antibody.

We have established a new method capable of measuring the very low concentrations of oxidized low density lipoprotein (OxLDL). In our previous study, we obtained a novel murine monoclonal antibody against oxidized lipoproteins (Itabe, H. et al. 1994. J. Biol. Chem. 269: 15274-15279). The epitope of this antibody resides in oxidized products of phosphatidylcholine that can form complexes with polypeptides, including apolipoprotein B. When the monoclonal antibody was precoated onto microtiter wells prior to carrying out a sandwich ELISA using an anti-human apolipoprotein B antibody, it was possible to detect 0.5 ng protein of copper-induced OxLDL. The detection of OxLDL was dependent on the presence of monoclonal antibody and was blocked by oxidized phosphatidylcholine (OxPC). Under the same sandwich ELISA condition, native LDL showed a dose-dependent increase of absorbance that was inhibited by complex of OxPC with BSA. These results suggest the possible occurrence of oxidative modification of human plasma LDL, which is recognized by the antibody against OxPC. The level of LDL oxidation of normal human subjects was found to be 0.52 +/- 0.35 units per 5 mu g protein of LDL, where one unit was defined as the reactivity corresponding to 1 ng of copper-induced OxLDL by this assay. Furthermore, we found that the LDL oxidation level in patients who had been receiving hemodialysis treatment was increased more than eightfold over that of normal subjects. We suggest that LDL in human plasma is oxidatively modified under certain conditions and this method for measurement of OxLDL could be used to study the relationship between in vivo oxidation reaction and various pathological conditions.

Antibodies, Monoclonal↗
PubMed1996

Large vertebral body, in addition to narrow spinal canal, are risk factors for cervical myelopathy.

It is well known that a narrow spinal canal is frequently associated with cervical spondylotic myelopathy. However, few investigators have studied the relationship between the size of the cervical spinal canal and that of the cervical spinal cord. Moreover, no studies mention the correlation between the size of the vertebral body and that of the spinal canal in the pathogenesis of cervical myelopathy. In the present study, we used computed tomographic myelography to measure the size of the vertebral body, spinal canal, and spinal cord in patients who had classic cervical myelopathy and in control subjects. We found that patients with cervical spondylotic had a narrow spinal canal as well as a slender spinal cord in the cervical region. Moreover, the vertebral body is significantly larger in the myelopathy group than in controls. A large vertebral body is thought to be associated with a large osteophyte and large disc protrusion. We conclude that a large vertebral body is another risk factor for cervical myelopathy, along with a narrow spinal canal.

Adult↗
PubMed1996

Anterior cervical plate used in degenerative disease can maintain cervical lordosis.

The aim of this study was to show whether anterior cervical plate stabilization is able to maintain cervical lordosis or not when used for cervical degenerative disease. Thirty cases that underwent anterior fusion at multiple levels without cervical plating before 1986 were compared with 44 cases treated with cervical plating since 1986. Changes in the alignment of the total cervical spine and of the fused segment were studied in both groups. Collapse of the grafted bone, which was observed in 9 of 30 cases in the nonplate group, was not observed in the plate group. Alignment of the cervical spine was corrected and well maintained in the plated group, compared with the nonplate group. Anterior cervical plate stabilization could maintain the normal alignment of the cervical spine damaged by degenerative processes, whereas anterior cervical fusion without plating could not.

Cervical Vertebrae↗
PubMed1995

An abnormally acidic TATA-binding protein from a hyperthermophilic archaeon.

The gene encoding the TATA-binding protein (PkTBP) from a hyperthermophilic archaeon, Pyrococcus sp. KOD1 (Pk), was cloned and sequenced. An open reading frame with homology to the conserved C-terminal core region of eukaryotic TBP was expressed in Escherichia coli. Specific DNA-binding activity of the recombinant PkTBP (190 amino acids, 21.36 kDa) was also demonstrated. Although it was composed of a structurally direct repeat sequence which is similar to eukaryotic TBP, the total net charge of archaeal TBP was amazingly negative (calculated isoelectric point (pI) was 4.66 and experimentally estimated pI was 4.8). A series of five Glu residues was found at the C terminus of archaeal TBP. These data strongly suggest that a positively charged protein is also involved in the transcription initiation event which might stabilize the structure of the genomic DNA under high-growth-temperature conditions.

Amino Acid Sequence↗
PubMed1995

Thermostable peroxidase activity with a recombinant antibody L chain-porphyrin Fe(III) complex.

In order to engineer a new type of catalytic antibody, we attempt to use a monoclonal antibody L chain as a host protein for a porphyrin. TCPP (meso-tetrakis(4-carboxyphenyl)porphyine) was chemically synthesized and Balb/c mice were immunized using TCPP as a hapten. Two hybridoma cells (03-1, 13-1), that produce monoclonal antibody against TCPP, were obtained. Genes for both H and L chains of monoclonal antibodies were cloned, sequenced and overexpressed using E. coli as a host. ELISA and fluorescence quenching method show that the independent antibody L chains from both Mab03-1 and Mab13-1 have specific interaction with TCPP. Furthermore, the recombinant antibody L chain from Mab13-1 exhibits much higher peroxidase activity than TCPP Fe(III) alone. The enzyme activity was detectable with pyrogallol and ABTS (2,2-azinobis-3-ethylbenzthiazolin-6-sulfonic acid) but not with catechol. This new catalytic antibody was extremely thermostable. Optimum temperature of the peroxidase reaction by the complex of 13-1L chain and TCPP Fe(III) was 90 degrees C, while that the TCPP Fe(III) alone was 60 degrees C.

Amino Acid Sequence↗
PubMed1995

Aspartyl-tRNA synthetase of the hyperthermophilic archaeon Pyrococcus sp. KOD1 has a chimerical structure of eukaryotic and bacterial enzymes.

The aspartyl-tRNA synthetase (AspRS)-encoding gene from the archaeon, Pyrococcus sp. KOD1 (KOD1), was cloned and sequenced, and expressed in Escherichia coli. The purified AspRS possessed an aminoacyation activity for tRNA extracted from KOD1. Analysis of the deduced amino-acid sequence (438 aa, 50,893 Da) revealed that the AspRS of KOD1 is a chimerical protein of bacteria and eukarya. Regional analysis showed high sequence similarity to higher eukaryotic enzymes in the central and C-terminal regions which are important for catalytic activity of the enzyme. In contrast, the N-terminal portion exhibits bacterial features and does not possess the higher eukaryotic sequence which is involved in high molecular weight (HMW) complex formation. These results suggest that archaeon AspRS has a eukaryotic-type catalytic mechanism without forming the HMW complex. This is the first example which shows that an archaeal protein possesses eukaryotic and bacterial features.

Amino Acid Sequence↗
PubMed1995

Platelet-derived growth factor triggers translocation of the insulin-regulatable glucose transporter (type 4) predominantly through phosphatidylinositol 3-kinase binding sites on the receptor.

Insulin is the only known hormone which rapidly stimulates glucose uptake in target tissues, mainly by translocation to the cell surface of the intracellular insulin-regulatable glucose transporter (glucose transporter type 4, GLUT4). We have developed a cell line for direct, sensitive detection of GLUT4 on the cell surface. We have suggested that insulin-activated phosphatidylinositol (PI) 3-kinase may be involved in the signaling pathway of insulin-stimulated GLUT4 translocation. We report that platelet-derived growth factor (PDGF), which stimulates PI 3-kinase activity, triggers GLUT4 translocation in Chinese hamster ovary (CHO) cells stably overexpressing the PDGF receptor and in 3T3-L1 mouse adipocytes. Using mutant PDGF receptors that cannot bind to Ras-GTPase-activating protein, phospholipase C-gamma, and PI 3-kinase, respectively, we obtained evidence that PI 3-kinase binding sites play a key role in the signaling pathway of PDGF-stimulated GLUT4 translocation in the CHO cell system.

3T3 Cells↗
PubMed1995

Active site analysis and stabilization of sarcosine oxidase by the substitution of cysteine residues.

Two cysteine residues (C-265 and C-318) in the putative hydrophilic regions of sarcosine oxidase were substituted by using site-directed mutagenesis. Since the mutant with the C-to-S mutation at position 318 (C318S) lost the enzyme activity, C-318 (conserved among sarcosine oxidases) is most likely a part of the active site. C265S, C265A, C265D, and C265R showed nearly the same enzymatic properties as those of the wild type. However, they were much more stable than the wild type in the presence of inhibitors that modified the thiol group. Moreover, they were extremely stable throughout the cultivation of the recombinant strains or even in cell extracts.

Arthrobacter↗
PubMed1995

Thiamine deficiency and pulmonary hypertension in Crow-Fukase syndrome.

A 57-year-old woman with Crow-Fukase syndrome presented thiamine deficiency and pulmonary hypertension of unknown etiology. After oral administration of prednisolone and thiamine, echocardiogram showed marked improvement of the pulmonary hypertension. To our knowledge, this is the first case of this syndrome associated with thiamine deficiency and precapillary pulmonary hypertension, which may play a role in the pathogenesis of polyneuropathy and heart failure of this syndrome.

Drug Therapy, Combination↗
PubMed1995

Frequency of mutations of insulin receptor gene in Japanese patients with NIDDM.

To examine the prevalence of abnormalities in the insulin receptor structure gene in Japanese with non-insulin-dependent diabetes mellitus (NIDDM), a population of 51 patients with NIDDM was screened for mutations in this gene. Patient genomic DNAs of both alleles corresponding to 22 exons of the gene were amplified by polymerase chain reaction (PCR). The PCR products on pUC19 were sequenced. Three patients with heterozygous missense mutation Thr831-->Ala831 in exon 13 and one patient with heterozygous missense mutation Tyr1334-->Cys1334 in exon 22 of the beta-subunits were identified. Linkage analysis of one of the families plus statistical studies showed that the mutation Thr831-->Ala831 is possibly responsible for the onset of NIDDM. In COS cells transiently expressing both mutant receptor cDNAs and a cDNA of a M(r) 85,000 regulatory subunit of phosphatidylinositol 3-kinase (PI 3-kinase), the mutation Tyr1334-->Cys1334 impaired binding of the receptor with the M(r) 85,000 subunit of PI 3-kinase, but linkage analysis of the family showed that the mutation did not cosegregate with NIDDM in the pedigree. Therefore, one missense mutation (Thr831-->Ala831) in the insulin receptor, as found in three patients, is possibly involved in the etiology of a subset of the 51 NIDDM patients.

Adult↗
PubMed1995

Involvement of von Willebrand factor and PGI2 in platelet binding to a partially denuded endothelial monolayer.

Platelet binding to an endothelial monolayer was examined after denudation. The binding increased for up to 10 min and thereafter declined gradually. Antibodies against von Willebrand factor (vWF) inhibited the binding. Production of prostacyclin (PGI2) occurred 10 min after endothelial denudation. This study suggests that vWF is involved in the binding during the first 10 min and that PGI2 suppresses the binding thereafter.

Blood Platelets↗
PubMed1995

Comparison of HIV-1 protease expression in different fusion forms.

Earlier observations showed that the expression of recombinant protease of human immunodeficiency virus type-1 (HIV-1 PR) was usually in a low level, and its proteolytic activity and hydrophobicity were believed to be toxic for the host cells. Various constructs were investigated that contained an N-terminal extended HIV-1 PR gene (PR107) in order to find a system which can express this protease in high level. The constructs of PR107 gene expressed as fusion proteins either with glutathione S-transferase (GST) by pGEX-PR107 or with maltose-binding protein (MBP) by pMAL-PR107 showed that the full length of fusion protein exhibited self-cleavage in E. coli. The results from expression experiments indicated that the size of the fusion portion does not affect the self-processing of fused HIV-1 PR to release its mature form, despite the attachment of only one subunit of the dimeric protease to GST or MBP. The construct, pET-PR107, under the control of strong bacteriophage T7 promoter system, did not show clear advantages for expression of this HIV-1 PR. Comparing these three constructs, the pGEX-PR107 system showed the highest expression level. Quantitative immuno-blotting indicated that the amount of HIV-1 PR expressed by pGEX-PR107 was twice that expressed by pMAL-PR107, and thrice that expressed by pET-PR107. More than 1 mg of pure HIV-1 PR from per liter culture of E. coli. DH5 alpha containing pGEX-PR107 can be obtained via the purification procedures [Biochem. Mol. Biol. International, (1995) 35:899-912].(ABSTRACT TRUNCATED AT 250 WORDS)

ATP-Binding Cassette Transporters↗
PubMed1994

Epidermal growth factor triggers the translocation of insulin-responsive glucose transporter (GLUT4).

In a novel cell line we developed for direct, sensitive detection of insulin-responsive glucose transporter (GLUT4) on the cell surface, we considered that insulin-activated phosphatidylinositol 3-kinase (PI 3-kinase) may be involved in the signaling pathway of insulin-stimulated GLUT4 translocation. We report here evidence that epidermal growth factor (EGF), which stimulates PI 3-kinase activity, also triggers GLUT4 translocation in Chinese hamster ovary (CHO) cells stably overexpressing the EGF receptor. The EGF-dependent GLUT4 translocation is possibly mediated by two independent pathways: one by PI 3-kinase and the other by protein kinase C (PKC); the PI 3-kinase-mediated pathway predominates. Triggering of the GLUT4 translocation is not specific for insulin, rather it may be a common property of growth factors which activate PI 3-kinase.

Androstadienes↗