PubMed Health⌕ Search

Biomedical subjects

Akira Tanaka

Publications and source records attributed to Akira Tanaka.

At least 19 recordsLinked to original sources
PubMed2007

Recombinant annexin-2 inhibits the progress of diabetic nephropathy in a diabetic mouse model via recovery of hypercoagulability.

Diabetic nephropathy, a major complication of diabetes mellitus that leads to mortality, has been shown to involve a dysregulation of the coagulation system. Annexin-2, a co-receptor for plasminogen and tissue plasminogen activator on endothelial cells, is one of the molecules required to maintain the antithrombogenic properties of endothelial cells. Previously, we showed that recombinant annexin-2 protein (rAN II) modulated impaired fibrinolytic activity in the carotid arteries of rats. In the present study, to investigate its protective effects against diabetic nephropathy, rAN II was administered to KK-Ay mice, a murine model of type 2 diabetes, for eight weeks, and albuminuria, kidney size, and histological glomerular lesions were investigated. The mean weight of kidneys from KK-Ay mice treated with rAN II was significantly less than that of those treated with PBS (control) (p < 0.02). Furthermore, the level of albuminuria observed in rAN II-treated KK-Ay mice was significantly less than that of the control group (rAN II, 0.90+/-0.12 microg/day; PBS, 1.55+/-0.31 microg/day; p < 0.01); also, the area of diffuse glomerular lesions was significantly smaller (rAN II, 41.51+/-4.54%; PBS, 81.81+/-8.10%; p < 0.01). Bleeding time, prothrombin time (PT), and active partial thromboplastin time (APTT) did not significantly differ between the two groups. Our results suggest that rAN II may inhibit the progression of diabetic nephropathy in KK-Ay mice without influencing the coagulation system, indicating that annexin-2 may be considered as a possible new therapeutic tool for patients with diabetic nephropathy.

Albuminuria↗
PubMed2007

[Case of ruptured superior cerebellar artery dissection treated by endovascular embolization].

The authors herein report a case of a ruptured dissection of the superior cerebellar artery (SCA). A 68-year-old man presented with symptons of sudden headache and nausea. The CT scan revealed the presence of both a subarachnoid hemorrhage (SAH) and acute hydrocephalus. The left vertebral angiogram showed an fusiform dilatation in the cerebellomesencephalic segment of the left SCA. Endovascular embolization of the aneurysm and SCA was successfully performed using Guglielmi detachable coils (GDCs). No delayed ischemic deficits were observed after the treatment. A dissection of the distal segment of the SCA is a very rare occurrence. We believe endovascular embolization using GDCs to be an effective and less invasive therapy for the treatment of an SCA dissection with SAH.

Aged↗
PubMed2006

Stent fracture in revascularization for symptomatic ostial vertebral artery stenosis.

INTRODUCTION: We assessed the long-term follow-up examinations and complications of percutaneous transluminal angioplasty and stenting (PTAS) for symptomatic ostial vertebral artery (VA) stenosis. METHODS: A retrospective study was done to evaluate 12 patients with symptomatic ostial VA stenosis who underwent PTAS. Six patients were treated with the Palmaz stent and six with a balloon-expandable coronary stent. Initial angiographic follow-up examination was conducted about 12 months after PTAS in all patients. Simple radiographic, ultrasonographic and clinical follow-up examinations were scheduled every 6 months. RESULTS: Excellent dilatation was achieved in all patients without any procedural complications. Initial angiographic follow-up obtained at a mean of 13 months after PTAS detected no restenosis. However, an asymptomatic severe restenosis was detected at 24 months after PTAS in one patient (8%). During a mean follow-up of 31.5 months, three stent fractures were detected in deployed coronary stents (50%). None of the stent fractures was associated with either recurrent stroke or restenosis. No patients developed recurrent symptoms during the follow-up period. CONCLUSION: PTAS for symptomatic ostial VA stenosis is effective in preventing recurrent stroke. As the open-cell single-joint type of stent is associated with the risk of fracture, long-term follow-up examinations including simple radiography are needed.

Aged↗
PubMed2006

Suppressive effects of diacylglycerol oil on postprandial hyperlipidemia in insulin resistance and glucose intolerance.

The diacylglycerol (DAG), a commonly used as a cooking oil in Japan, results in a lower elevation of serum triglyceride (TG) after ingestion compared to triacylglycerol (TAG). Postprandial hyperlipidemia (PPHL) and an increase in remnant lipoproteins (RLP) levels are risk factors for CAD, and a close relationship between PPHL and type 2 diabetes and/or insulin resistance has been reported. To evaluate the effect of DAG on PPHL in insulin resistance and glucose intolerance, 11 subjects with a normal glucose tolerance (NGT) and 14 subjects with IGT received oral fat tolerance test (OFTT) twice. They ingested emulsified test oils prepared with either DAG or TAG. In the IGT subjects, after the DAG and TAG load, the serum concentrations of TG, RLP-TG, and RLP-cholesterol increased throughout the 4-h study. The responses of these variables above baseline after the DAG load were significantly smaller than those after the TAG load (p<0.05). In contrast, in the NGT subjects, changes in these parameters were much smaller than those observed for IGT subjects. The difference in the integrated responses for serum RLP-cholesterol concentration during OFTT between DAG and TAG in all subjects can be easily explained by the integrated response of insulin rather than glucose during oral glucose tolerance test (r=0.7, p<0.01). DAG was more effective in insulin resistant and hyperinsulinemic participants regardless of glucose intolerance, and may be beneficial in reducing the extent of CAD risk in such individuals.

Adult↗
PubMed2006

Circadian rhythm of serum concentration of small dense low-density lipoprotein cholesterol.

BACKGROUND: The atherogenicity of small dense low-density lipoprotein (sdLDL) has been reported and recently a new easy-handling method for measuring serum concentration of sdLDL cholesterol (sdLDLC) has been developed. Using this method, we observed the circadian rhythm of sdLDLC to determine the adequacy of fasting measurement of it and to seek the modulator of the atherogenic lipoprotein. METHODS: Study population was consisted of 20 healthy volunteers (10 women and 10 men, mean age 28 y). They had 3 meals per day and blood samples were taken before and 2 h after every meal and next morning. Serum concentrations of sdLDLC and other valuables including triglyceride (TG) and remnant-like particles cholesterol (RLPC) were determined. RESULTS: Serum concentration of sdLDLC had a unique circadian rhythm that was highest before breakfast (fasting status), decreased after each meal, hit the bottom after dinner and then increased during at night. Fasting sdLDLC was highly correlated with TG levels. The sum of the 6 TG values during a day (i.e., average TG level) had higher correlation coefficient with sdLDLC than fasting TG or fasting RLPC. CONCLUSIONS: From the observation of the unique circadian rhythm, measuring sdLDLC at fasting status is exactly reasonable because it never underestimate the risk of atherosclerotic diseases. Measuring sdLDLC can also be used as a marker for average TG levels regardless of the existence of postprandial hyperlipidemia.

Adult↗
PubMed2006

Intravascular two-dimensional tissue strain imaging.

Our goal is to achieve the precise quantitative imaging of tissue elasticity in clinical settings. In the present study, we measured basic ultrasonic characteristics of atherosclerosis by two-dimensional (2D) intravascular tissue velocity imaging. Radio-frequency (RF) signal from a clinically used IVUS apparatus was digitized at 500 MSa/s and stored in a workstation. First, the correlation coefficient between two consecutive frames was calculated in the rotational direction and the rotational disuniformity was corrected to obtain the maximum correlation coefficient. Then, the polar coordinate images were converted into rectangular coordinate images and the images were divided into 64 by 64 square shaped regions of interest (ROIs). The correlation and displacement of the ROIs between the consecutive two frames were calculated by template matching method. Two-dimensional tissue velocity was defined as the vectors of displacement of ROI with 0.7 and more correlation. IVUS studies were performed in directional coronary atherectomy (DCA) procedures. The specimens excised by DCA were stained with Elastica-Masson's trichrome staining and CD68 immunochemical staining. Eleven cases (including two no re-flow cases and one perforation case) were intraoperatively observed by IVUS and the specimens obtained by DCA were observed by optical microscopy. The specimen from homogeneous 2D strain was collagen dominant fibrosis and the specimen from a lesion with complex vectors contained CD68 positive cells and degenerated collagen fibers, which indicated the plaque was vulnerable.

Algorithms↗
PubMed2006

Expression of matrix metalloproteinases and aggrecanase in the synovial fluids of patients with symptomatic temporomandibular disorders.

OBJECTIVE: To investigate whether matrix metalloproteinases (MMPs) and/or aggrecanase in synovial fluid can be used as biochemical markers in the diagnosis of internal derangement (ID) of the temporomandibular joint (TMJ). STUDY DESIGN: Forty-four samples of synovial fluid were obtained from 35 patients with ID and osteoarthritis (OA) and 15 normal samples from 10 asymptomatic volunteers. MMP-2, -9, and aggrecanase in the synovial fluid were examined by immunoblotting. RESULTS: The incidences of MMP-2, -9, and aggrecanase expression in the ID and OA group were significantly higher than those in the normal group (P < .05). Those with anterior disc displacement without reduction and severe OA showed significantly high expression of MMP-9 compared with other disease subgroups (P < .05). Conversely, comparatively high expression of MMP-2 and aggrecanase was shown in the early-stage OA group. However, there was no significant difference in expression of MMP-2 and aggrecanase among disease subgroups. CONCLUSIONS: These findings suggested that expression of aggrecanase could be a potential biochemical marker for articular cartilage degradation in ID of the TMJ.

Adolescent↗
PubMed2006

Postfluorination of fluoride films for vacuum-ultraviolet lithography to improve their optical properties.

Transmittance of fluoride films prepared by various kinds of deposition methods is not sufficient for a vacuum-ultraviolet (VUV) stepper application. Moreover, moisture penetrates into fluoride films because of porous structures. Then the moisture reacts with the fluoride chemically, and the photoabsorption of the films increases with elapsed time. Postfluorination treatment, in which F-poor areas of fluoride films are sufficiently fluorinated and the film structures are modified to be denser, has been developed. The postfluorination treatment was performed at 0.1 MPa of diluted F2 gas in a special apparatus made of nickel. This treatment reduces photoabsorption of fluoride films and prevents photoabsorption from increasing again with elapsed time. In a long-time F2 laser irradiation test, the transmittance of as-deposited fluoride films remarkably degraded with irradiation. On the other hand, there is no tendency of transmittance degradation in the case of postfluorinated fluoride films. The postfluorination is able to improve the optical performance of fluoride films, promising the highest coating level for VUV lithography.

Journal Article↗
PubMed2006

Preparation of high-performance optical coatings with fluoride nanoparticle films made from autoclaved sols.

An ultralow refractive index is very advantageous when one designs antireflective coatings. We successfully obtained high-quality MgF2 thin films with ultralow refractive indices from autoclaved sols prepared from magnesium acetate and hydrofluoric acid. The MgF2 films consist of nanosized particles, and they have high laser-exposure durability at 193 nm. The reflectance of the antireflective coating with five layers, of which the top layer is formed by our method, is lower than 0.6% in the incident angle range of 0 degrees - 60 degrees at 193 nm.

Journal Article↗
PubMed2006

The oxidative modification hypothesis of atherosclerosis: the comparison of atherogenic effects on oxidized LDL and remnant lipoproteins in plasma.

A tremendous number of articles on oxidized LDL (Ox-LDL) and scavenger receptor in macrophage have been published since Steinberg proposed Ox-LDL hypothesis as the major cause of atherosclerosis. This hypothesis has provided strong support for the efficacy of LDL lowering drugs, indicating that lowering LDL means lowering Ox-LDL in vivo. This manuscript proposed a new oxidative modification hypothesis that remnant lipoproteins determined as remnant-like lipoprotein particles (RLP), not LDL are the major oxidized lipoproteins in plasma, resulting from the plasma concentration of these oxidized lipoproteins. Remnant lipoproteins may play a pivotal role for the initiation of atherosclerosis via lectin-like oxidized LDL receptor-1 (LOX-1) in endothelial cells. Isolated remnant lipoproteins were found to be oxidized or susceptible to be oxidized in plasma, not necessary to be further oxidized in vitro as Ox-LDL. High similarity of proatherogenic and proinflammatory properties of isolated Ox-LDL and remnant lipoporteins have been reported and predicted the presence of similar oxidized phospholipids in both lipoproteins as bioactive components. These results suggest the possibility that reducing plasma remnant lipoproteins rather than LDL should be the target for hyperlipidemic therapy especially in patients with metabolic syndrome for the prevention of endothelial dysfunction in the initiation of atherosclerosis.

Animals↗
PubMed2006

Vitamin D3 suppresses the androgen-stimulated growth of mouse mammary carcinoma SC-3 cells by transcriptional repression of fibroblast growth factor 8.

Active metabolites of vitamin A and D are well known to act as growth inhibitors in hormone-related prostate and breast cancers. When various concentrations of 1alpha,25-dihydroxyvitamin D3 (vitamin D3), all-trans-retinoic acid (ATRA) and 9-cis retinoic acid (9-cis RA) were examined, the androgen-stimulated growth of mouse mammary carcinoma SC-3 cells was inhibited by vitamin D3 alone in a dose-dependent manner. A flow cytometer analysis showed that vitamin D3 leads SC-3 cells to relative G1-growth arrest after 72 h. Characterization of vitamin D3-responsive genes using an oligonucleotide microarray demonstrated that 220 genes were upregulated at more than threefold, and 84 genes were downregulated to less than one-third, compared with the testosterone-stimulated SC-3 cells. Neither cyclin-dependent kinase inhibitors (CDKIs) nor the antiapoptotic bcl-2 gene were induced in vitamin D3-responsive genes, with the exception of a slight induction of p15(INK4B). Importantly, fgf8 was markedly repressed in response to vitamin D3. The exogenous addition of FGF8 canceled the growth suppression by vitamin D3 in SC-3 cells, suggesting that the repression of fgf8 is an indispensable step in vitamin D3-mediated growth inhibition. In reporter assays using the ARE-containing artificial construct and the natural androgen-regulated PSA promoter, co-transfection of the vitamin D receptor (VDR) and androgen receptor (AR) suppressed AR-stimulated promoter activity. In addition, vitamin D3 also suppressed androgen-stimulated promoter activity in the stably transfected SC-3 cells. Moreover, VDR repressed the core promoter activity of fgf8 in COS1 cells and in the SC-3 cells. All these findings strongly suggest that vitamin D3 serves as a negative regulator for both androgen-related and fgf8 transcriptions.

Androgens↗
PubMed2006

A novel role of L-serine (L-Ser) for the expression of nuclear factor of activated T cells (NFAT)2 in receptor activator of nuclear factor kappa B ligand (RANKL)-induced osteoclastogenesis in vitro.

Multinucleated cell formation is crucial for osteoclastogenesis, and the expression of nuclear factor of activated T cells (NFAT)2 (NFATc1) is essential for this process. We previously found, using mouse RAW264 cells, that culture at high cell density blocked progression to the multinucleated cell stage induced by stimulation with receptor activator of nuclear factor kappaB ligand (RANKL). Here, we have confirmed this finding in a bone marrow cell system and extended the analysis further. A high cell density appeared to cause a change in the composition of the culture medium accompanying downregulation of NFAT2 expression, and we identified L-serine (LSer) as essential for the expression of NFAT2 induced by RANKL. Namely, culture at high cell density caused a depletion of LSer in the medium. Consequently, L-Ser appeared to exert its effect at an early stage under the regular conditions used for inducing the expression of c-Fos, an upstream regulator of NFAT2. D-Ser, an enantiomer of L-Ser, showed no NFAT2-inducing activity. The expression of NFAT2, using a retrovirus vector, could compensate for the depletion of L-Ser and resume the progression to the multinucleated cell stage. These results demonstrate a novel role for L-Ser in RANKL-induced osteoclastogenesis in vitro.

Animals↗
PubMed2006

Catechin conjugated with fatty acid inhibits DNA polymerase and angiogenesis.

Catechins in green tea have anticancer and antiangiogenesis activities, with epigallocatechin-3-gallate (EGCG) being the most potent antiangiogenic tea catechin. This study examined whether chemical modification of catechin enhanced anticancer and antiangiogenic effects. Catechin, conjugated with fatty acid (acyl-catechin), strongly inhibited DNA polymerase, HL-60 cancer cell growth, and angiogenesis. Catechin conjugated with stearic acid [(2R,3S)-3',4',5,7-tetrahydroxyflavan-3-yl octadecanoate; catechin-C18] was the strongest inhibitor in DNA polymerase alpha and beta and angiogenesis assays. Catechin-C18 also suppressed human endothelial cell (HUVEC) tube formation on the reconstituted basement membrane, suggesting that it affected not only DNA polymerases but also signal transduction pathways in HUVECs. These data indicate that acyl-catechins target both DNA polymerases and angiogenesis as anticancer agents. These results suggest that acylation of catechin is an effective chemical modification to improve the anticancer activity of catechin.

Acylation↗
PubMed2006

Current cat ownership may be associated with the lower prevalence of atopic dermatitis, allergic rhinitis, and Japanese cedar pollinosis in schoolchildren in Himeji, Japan.

The aim of the study was to clarify the relationship between current pet ownership, passive smoking, and allergic diseases among the Japanese children. From 1995 to 2001, we distributed the Japanese edition of the questionnaire of the American Thoracic Society and the Division of Lung Diseases (ATS-DLD) to survey allergic diseases among 35,552 6-yr-old children at primary school in the city of Himeji, Japan. We analyzed the data by multiple logistic regression and calculated adjusted odds ratios for environmental factors, including passive smoking and pet (dog and/or cat) ownership. There were no significant relationships between the prevalence of asthma and current pet ownership and passive smoking. However, current cat ownership was related to a significantly lower prevalence of atopic dermatitis [adjusted odds ratio (aOR) 0.79, 95% confidence interval (CI) 0.67-0.93], allergic rhinitis (aOR: 0.71, 95% CI 0.57-0.89) and Japanese cedar pollinosis (aOR 0.57, 95% CI 0.44-0.75). Strikingly, passive smoking was also related to a significantly lower prevalence of allergic rhinitis (aOR 0.83, 95% CI 0.77-0.89) and Japanese cedar pollinosis (aOR 0.81, 95% CI 0.74-0.88). Current cat ownership was associated with a lower prevalence of atopic dermatitis, allergic rhinitis, and Japanese cedar pollinosis. In addition, passive smoking was also associated with a lower prevalence of allergic rhinitis and Japanese cedar pollinosis.

Allergens↗