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Biomedical subjects

N Kume

Publications and source records attributed to N Kume.

At least 55 records · Page 3Linked to original sources
PubMed2000

Identification of soluble forms of lectin-like oxidized LDL receptor-1.

Lectin-like oxidized LDL receptor-1 (LOX-1) is a type II membrane protein belonging to the C-type lectin family molecules, which can act as a cell-surface endocytosis receptor for atherogenic oxidized LDL. In this study, we show that soluble forms of LOX-1 are present in conditioned media of cultured bovine aortic endothelial cells (BAECs) and CHO-K1 cells stably transfected with LOX-1 cDNA. Immunoblot analysis of conditioned media from TNF-alpha-activated BAECs and CHO-K1 cells stably expressing LOX-1 revealed that soluble LOX-1 has an approximate molecular mass of 35 kDa. In TNF-alpha-activated BAECs, cell-surface expression of LOX-1 precedes soluble LOX-1 production. Cell-surface biotinylation followed by immunoprecipitation and immunoblotting showed that soluble LOX-1 in cell-conditioned media is derived from LOX-1 expressed on the cell surface. Production of soluble LOX-1 was inhibited by PMSF, suggesting that PMSF-sensitive proteases may be involved in this process. Purification of soluble LOX-1 by high-performance liquid chromatography and N-terminal amino acid sequencing of soluble LOX-1 identified the 2 cleavage sites between Arg(86)-Ser(87) and Lys(89)-Ser(90), which were located in the membrane proximal extracellular domain of LOX-1. The data demonstrate that cell-surface LOX-1 can be cleaved at 2 different sites and transformed into soluble forms. Further studies may explore therapeutic and diagnostic applications of soluble LOX-1 in atherosclerotic diseases.

Amino Acid Sequence↗
PubMed2000

Increased expression of lectin-like oxidized low density lipoprotein receptor-1 in initial atherosclerotic lesions of Watanabe heritable hyperlipidemic rabbits.

A novel lectin-like oxidized low density lipoprotein receptor-1 (LOX-1) was recently identified in bovine aortic endothelial cells. It is strongly suggested to have a potential role in the initiation and development of atherosclerosis. In this study, we have isolated cDNA clones encoding the rabbit homologue of LOX-1 by screening a rabbit placenta cDNA library. In amino acid sequence and domain structure organization, the rabbit LOX-1 is highly conserved with the human counterpart. Transfection of rabbit LOX-1 cDNA to HEK-293 cells confers on them the activity to bind and internalize oxidized low density lipoprotein. Rabbit LOX-1 was identified as a 45-kDa protein by Western blot analysis with a specific monoclonal antibody. Notably, analyses by reverse transcription-polymerase chain reaction and Western blot revealed that LOX-1 was accumulated in 8-week-old Watanabe heritable hyperlipidemic rabbit aortas compared with normal rabbit aortas. Immunostaining confirmed that the augmented expression of LOX-1 was primarily localized within the intima at the earliest stages of atherogenesis. The most prominent staining was in the endothelial cells of lesions. Furthermore, the distinctive staining of LOX-1 was identified in the endothelium of non-lesion areas of Watanabe heritable hyperlipidemic rabbit aortas. Taken together, these findings support the possibility that LOX-1 might be involved in the initiation of atherosclerosis.

Amino Acid Sequence↗
PubMed2000

Brain fluorine-18 fluorodeoxyglucose imaging with dual-head coincidence gamma camera: comparison with dedicated ring-detector positron emission tomography.

BACKGROUND AND PURPOSE: Dual-head coincidence gamma camera (DHC) imaging has been proposed as an alternative to dedicated ring-detector positron emission tomography (dr-PET) for clinical fluorodeoxyglucose (FDG) studies. The purpose of this investigation was to assess the quality of DHC images in FDG studies of the human brain. METHODS: Seven healthy volunteers and 12 patients with various cerebral disorders underwent consecutive brain dr-PET and DHC with FDG. All sets of images were compared semiquantitatively using regions of interest. RESULTS: Cortical count ratios to the cerebellum on DHC and dr-PET images did not differ significantly among the volunteers, except in the superior frontal cortex and thalamus. In all studies including those of cerebral disorders, the mean cortical-to-cerebellar ratios of DHC and dr-PET images correlated closely. CONCLUSION: FDG imaging with DHC delineated the metabolic distribution of glucose in the brain as well as dr-PET did, except in the superior frontal cortex and thalamus. Therefore, DHC may be a dedicated cost-effective means of detecting metabolic abnormalities in the brain.

Adult↗
PubMed1999

Lysophosphatidylcholine phosphorylates CREB and activates the jun2TRE site of c-jun promoter in vascular endothelial cells.

Lysophosphatidylcholine (lyso-PC), a polar phospholipid increased in atherogenic lipoproteins and atherosclerotic lesions, has been shown to induce transcription of a variety of endothelial genes relevant to atherogenesis. Lyso-PC has been shown to activate c-jun N-terminal kinase (JNK) and activator protein 1 (AP-1) and thereby stimulate transcription of the c-jun gene. Here we provide evidence that lyso-PC can phosphorylate cyclic AMP responsive element binding protein (CREB) and thereby activate the jun2 12-O-tetradecanoylphorbol 13-acetate response element (jun2TRE) site of the c-jun promoter, which appears to be the major molecular mechanism involved in lyso-PC-induced c-jun gene expression in cultured bovine aortic endothelial cells (BAEC). Transient transfection of BAEC with a 1.6-kbp c-jun promoter and luciferase reporter fusion gene resulted in a 12.9-fold increase in luciferase activity by lyso-PC treatment. Serial deletion mutation in c-jun promoter and luciferase reporter gene assay revealed that the 5' promoter region between nucleotide numbers -268 and -127, which contains a jun2TRE binding sequence, was most crucial for lyso-PC-induced transcription. The 5' promoter region between -76 and -27, which contains an AP-1 site, also affected lyso-PC-induced transcription of the c-jun gene. Point mutation in the jun2TRE site reduced lyso-PC-induced transcription of the c-jun promoter-luciferase fusion gene by a 70.3% decrease in c-jun promoter activity. Electrophoretic mobility shift assays showed increased binding of (32)P-labeled oligonucleotides with jun2TRE in nuclear extracts isolated from lyso-PC-treated BAEC, which was abolished or supershifted by anti-CREB antibody. Immunoblotting with anti-phosphorylated CREB antibody showed rapid phosphorylation of this protein after lyso-PC treatment. These results indicate that lyso-PC phosphorylates CREB, which was then bound to the jun2TRE site of the c-jun promoter and activated transcription. Activation of jun2TRE may play a key role in the transcriptional activation of c-jun as well as other endothelial genes depending upon these transcription factors.

Animals↗
PubMed1999

Expression of lectinlike oxidized low-density lipoprotein receptor-1 in human atherosclerotic lesions.

BACKGROUND: Oxidized LDL (Ox-LDL) seems to play key roles in atherogenesis. Lectinlike Ox-LDL receptor-1 (LOX-1) is a recently identified cell-surface receptor for Ox-LDL. The relationship of this novel receptor for Ox-LDL to atherogenesis, however, has not yet been clarified. In this study, we explored the expression of LOX-1 in the atherosclerotic lesions of human carotid arteries. METHODS AND RESULTS: Using carotid endarterectomy specimens obtained from 21 patients and 2 samples of normal human aortas, we examined LOX-1 expression by reverse transcription-polymerase chain reaction and immunohistochemistry. In aortas without atherosclerosis, LOX-1 expression was undetectable by immunohistochemistry and negligible by reverse transcription-polymerase chain reaction. In carotid arteries, luminal endothelial cells covering early atherosclerotic lesions were more frequently positive for LOX-1 expression than those in advanced atherosclerotic lesions. Endothelial cells in the intimal neovasculature of advanced lesions also expressed LOX-1. In addition, macrophages and smooth muscle cells in the intima of advanced atherosclerotic plaques were positive for LOX-1 expression. CONCLUSIONS: LOX-1 may play important roles in Ox-LDL uptake and subsequent functional alteration in the luminal endothelium in early atherosclerotic lesions and in intimal neovascular endothelial cells in advanced plaques. Furthermore, LOX-1 may also be involved in Ox-LDL uptake and subsequent foam cell transformation in macrophages and smooth muscle cells in the atherosclerotic intima.

Aged↗
PubMed1999

Respiratory failure and pulmonary hypertension associated with Klippel-Feil syndrome.

A 28-year-old woman with a deformed thorax and kyphoscoliosis associated with Klippel-Feil syndrome developed respiratory failure with pulmonary hypertension. Pulmonary 133Xe ventilation and 99mTc-MAA perfusion scintigraphies showed maldistributions of lung ventilation and perfusion, and noticeably delayed 133Xe washout from the lungs. Dynamic breathing MR imaging showed poor and/or asynchronous respiratory movements of the chest wall and diaphragm. These findings indicate that the perfusion-ventilation imbalance, the decreased ventilatory turnover, and expiratory flow from the alveolar space partly derived from the impaired respiratory mechanics may be responsible for the respiratory complications in this patient.

Adult↗
PubMed1999

Potential of iodine-123 metaiodobenzylguanidine single-photon emission tomography to detect abnormal functional status of the pulmonary neuroadrenergic system in irradiated lung.

The potential of iodine-123 metaiodobenzylguanidine (MIBG) to detect functional abnormalities of the pulmonary neuroadrenergic system (PNS) in irradiated lung areas (ILAS) was preliminarily explored using single-photon emission tomography (SPET). The subjects included five healthy subjects and a total of 31 patients with peripheral-type lung cancer treated by radiation; 15 patients (group A) had received a dose of less than 36 Gy (mean +/- SD: 28.2 +/-6.2 Gy), and 16 patients (group B) had received a higher dose (mean +/- SD: 51.2 +/- 3.5 Gy) at the time of examination. MIBG SPET scans acquired 15 min and 3 h after injection were used to measure the MIBG uptake ratio (count ratio of the ILA to the contralateral non-ILA) and the clearance rate [percentage of (early counts - delayed counts)/early counts] from the ILAs without noticeable abnormal opacities on chest computed tomography scan. Lung perfusion changes were also assessed by technetium-99m macroaggregated albumin SPET. By contrast to the homogeneous MIBG uptake in the lungs of the healthy subjects, MIBG uptake was folcally decreased in correspondence with the ILAs in all patients, including 11 patients (73.3%) of group A with relatively preserved lung perfusion. The reduction MIBG uptake was significant (P<0.0001), and the MIBG clearance rate from the ILAs was also significantly faster than the clearance rates from the normal lungs and contralateral non-ILAs (both P<0.01). Group B patients showed significantly lower MIBG uptake and faster clearance from the ILAs than group A patients (P<0. 001 and P<0.05, respectively), although there was no significant difference in the clearance from the non-ILAs. Overall, MIBG uptake/clearance from the ILAs correlated significantly with the radiation dose in the 31 patients (r = -0.656; P<0.0001 and r = 0. 387; P<0.05, respectively). Perfusion changes were inversely correlated with the clearance from the ILAs (r = -0.432, P<0.05), but did not correlate with MIBG uptake. These preliminary results suggest that MIBG may have the potential to be a marker of abnormal functional status of the PNS produced by irradiation and may facilitate investigation of irradiation lung injury independently of morphological or lung perfusion changes.

3-Iodobenzylguanidine↗
PubMed1999

Lysophosphatidylcholine activates mitogen-activated protein kinases by a tyrosine kinase-dependent pathway in bovine aortic endothelial cells.

Lysophosphatidylcholine (lyso-PC) is a major component of an atherogenic lipoprotein. In this study, to investigate the involvement of mitogen-activated protein kinases in the signaling pathway by lyso-PC in endothelial cells, we measured the activity of extracellular signal-regulated kinase (ERK) and c-Jun N-terminal kinase (JNK) in bovine aortic endothelial cells. Lyso-PC activated ERK and JNK in a dose-dependent manner. However, the time courses of activation of these kinases were different. ERK and JNK activation by lyso-PC was inhibited by a tyrosine kinase inhibitor, herbimycin A, but not by a protein kinase C (PKC) specific inhibitor. We conclude, therefore, that lyso-PC-mediated ERK and JNK activation is caused by a tyrosine kinase-dependent mechanism, but not conventional types of PKC-dependent mechanisms.

Animals↗
PubMed1999

Oxidized LDL and expression of monocyte adhesion molecules.

Accumulation of substantial numbers of monocyte/macrophages, as well as activated T lymphocytes, in focal areas of arterial intima appears to be a hallmark of atherogenesis. Our report demonstrated that lysophosphatidylcholine (lyso-PC), a polar phospholipid component that is increased in atherogenic lipoproteins, such as oxidized LDL and remnants lipoproteins in diabetic and type III hyperlipidemic patients, can upregulate adhesion molecules for monocytes and T lymphocytes, and growth factors, such as heparin-binding epidermal growth factor-like growth factor and PDGF-A and B chains. Recently we identified the novel receptor for oxidized LDL, named Lox-1. Therefore in this paper we summarize the importance of the interaction between oxidized LDL and its receptor, LOX-1 in terms of early stage of atherogenesis.

Animals↗
PubMed1999

Tc-99m colloid and Ga-67 imaging of splenic inflammatory pseudotumor correlation with ultrasound, CT, and MRI.

Splenic inflammatory pseudotumor is extremely rare and may mimic splenic neoplasms, such as lymphomas or hamartomas, clinically and radiologically. A case of a surgically proved splenic inflammatory pseudotumor is presented in which Tc-99m colloid SPECT and Ga-67 scintigraphy characterized the changes in the spleen, but the findings of ultrasound and unenhanced CT and MRI were nonspecific. This report indicates the utility of radionuclide imaging for diagnosing splenic inflammatory pseudotumor.

Gallium Radioisotopes↗
PubMed1999

Resolved splenic accumulation of Tc-99m HMDP after recovery of disseminated intravascular coagulation in a patient with rhabdomyosarcoma.

Unusual, intense splenic radioactivity was seen on bone scintigraphy with Tc-99m HMDP in a 14-year-old boy with alveolar rhabdomyosarcoma complicated by disseminated intravascular coagulation. Abnormal splenic radioactivity was resolved after recovery from the disseminated intravascular coagulation. During treatment of disseminated intravascular coagulation and tumors, the patient received repeated blood transfusions, resulting in iron overload, but this did not prevent the abnormal splenic uptake from resolving. This case indicates that disseminated intravascular coagulation may be a cause of splenic accumulation of bone-seeking agents, and that abnormal splenic uptake can be resolved.

Adolescent↗
PubMed1999

Tc-99m DTPA used as reference imaging to evaluate the distribution of other tumor-seeking tracers in tumors associated with neurofibromatosis.

Two patients with multiple benign and malignant tumors associated with neurofibromatosis underwent radionuclide imaging with Tc-99m DTPA, Tl-201, and Ga-67. In these patients, Tc-99m DTPA accumulated intensively in both the benign and malignant tumors and localized and defined the extent of every tumor. In contrast, Ga-67 and Tl-201 uptake was seen only in focal areas of tumor where there was malignant transformation or at sites that showed progressive tumor growth. Tc-99m DTPA imaging accurately demonstrated areas of neoplastic involvement and identified the areas that would be seen with the other two tracers in individual tumors. Tc-99m DTPA may not always be used for the differential diagnosis of malignant and benign tumors of neurofibromatosis, but it can provide a reference pattern for imaging to evaluate accurately the distribution of Tl-201 and Ga-67 by mapping out the anatomic extent of these tumors.

Adolescent↗
PubMed1999

Viable tissue in an area of severely reduced perfusion demonstrated with I-123 iomazenil brain SPECT imaging of benzodiazepine receptors.

A 70-year-old woman who experienced transient left hemiparesis had 90% stenosis of the right internal carotid artery. CT revealed small low-density areas in the subcortical frontal area. Baseline cerebral blood flow was reduced, and vasoreactivity was poor in the right frontoparietal area according to I-123 IMP brain SPECT with acetazolamide. The distribution of I-123 iomazenil was normal on the delayed SPECT image but reduced in the early SPECT image, mimicking baseline cerebral blood flow. The distribution of I-123 iomazenil SPECT on the delayed image reflected the normal binding potential of the benzodiazepine receptor and thus identified viable tissue in an area of severely reduced perfusion. These findings were confirmed by positron emission tomography.

Acetazolamide↗