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Biomedical subjects

M Takemoto

Publications and source records attributed to M Takemoto.

At least 19 recordsLinked to original sources
PubMed2001

NK-104, a 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor, reduces osteopontin expression by rat aortic smooth muscle cells.

1. It has been suggested that osteopontin promotes the development of atherosclerosis, especially under diabetic conditions. 2. In the present study, we found that NK-104, a new potent synthetic inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A reductase, reduced osteopontin expression both at protein and mRNA levels in cultured rat aortic smooth muscle cells. 3. The inhibitory effect of NK-104 was almost completely reversed by mevalonate, suggesting that mevalonate or its metabolites play important roles in the regulation of osteopontin expression. 4. Furthermore, oral administration of NK-104 (3 mg kg(-1) day(-1) for 7 days) effectively suppressed abnormally upregulated expression of osteopontin mRNA in the aorta and kidney of streptozotocin-induced diabetic rats. 5. These data support a notion that NK-104 is a suitable drug for the treatment of diabetic patients with hypercholesterolaemia.

Administration, Oral↗
PubMed2001

Enhanced intra-abdominal visceral fat accumulation in patients with Werner's syndrome.

OBJECTIVE: Studies were made on the abnormality of glucose and lipid metabolism and its cause in four patients with Werner's syndrome to infer the reason for accelerated atherogenesis in this syndrome. RESULTS: Of these four patients, hypercholesterolemia was found in three, hypertriglyceridemia in four, hypoalphalipoproteinemia in two and hypertension in two. All the patients had insulin-resistant diabetes mellitus and three of them had apparent hyperinsulinemia. Abdominal computed tomography revealed that all of them had visceral fat obesity, namely augumented intra-abdominal adipose tissue. CONCLUSION: The clinical features of these patients resemble those recently designated as insulin resistant syndrome (syndrome X) or visceral fat syndrome. The metabolic abnormality may be one of important factors in the accelerated atherogenesis in this syndrome.

Abdomen↗
PubMed2001

The R3 region, one of three major repetitive regions of human herpesvirus 6, is a strong enhancer of immediate-early gene U95.

An immediate-early (IE) gene of human herpesvirus 6 (HHV-6), U95, has similarity at the amino acid level to the murine cytomegalovirus (MCMV) IE2 gene and is related to the human cytomegalovirus (HCMV) US22 gene family. Sequence analyses of U95 cDNA clones revealed that the transcription start site was located about 1.6 kbp upstream of the putative initiating ATG and that the transcript consisted of two exons. A single intron extended from nucleotides 142589 to 144229, which contained ORF U94. A protein with a molecular mass of about 120 kDa was translated from this cDNA clone in an in vitro transcription-translation assay. The transcription start site was found to be 220 bp downstream of the R3 region by primer extension analysis. HHV-6 has three repetitive elements, R1, R2, and R3, in or near the IE-A locus. R3 is composed of 24 copies of a 104- to 107-bp sequence element, which contains multiple putative binding sites for cellular transcription factors such as AP2 and NF-kappaB, and its biological significance has yet to be elucidated. The region between -710 and +46 relative to the transcription start site of U95 was analyzed in this study. Deletion from -710 to -396, corresponding to three copies of an R3 unit, decreased the promoter activity by 15-fold, and coexpression of IkappaBalpha(S32A/S36A) repressed it to almost the same level. Electrophoretic mobility shift assays showed that NF-kappaB family members p50 and c-Rel bound to NF-kappaB sites derived from the R3 region. These results demonstrate that R3 strongly enhances the U95 promoter activity and that NF-kappaB and binding sites for NF-kappaB in the R3 region play an important role in its activation. Because U95 promoter activity correlated with the number of R3 units, which each contained an NF-kappaB site, the repetitive organization of R3 is important for regulating U95 transcription.

Base Sequence↗
PubMed2001

[Relationship between endothelial dysfunction and nitric oxide production in young male smokers].

OBJECTIVES: Endothelial function in the brachial arteries is impaired in smokers. However, little is known about this condition in young adult men. The relationship between nitric oxide(NO) production and the endothelial function was investigated in young smokers and compared with non-smokers. METHODS: Flow-mediated vasodilation of the brachial artery during reactive hyperemia was examined in 10 young smokers(mean age 31 years) and 12 control subjects(mean age 28 years). The vasodilator response in the brachial artery was measured by ultrasonography, and blood samples were obtained from the right cephalic vein. Blood samples were taken at baseline, 30 sec after cuff deflation, and before and 5 min after 0.3 mg of nitroglycerin administration. Blood flow was calculated by multiplying mean flow velocity and vessel cross-sectional area. Plasma NOx(nitrate + nitrite) levels were measured, and the percentage change of NOx production(delta NOx) was calculated as follows: delta NOx(%) = [(NOx concentration at peak flow-mediated vasodilation or after 0.3 mg nitroglycerin administration) - baseline NOx concentration)] x 100/baseline NOx concentration. RESULTS: Percentage changes in diameter of the brachial artery, NOx production and delta NOx in response to nitroglycerin were not statistically different between the two groups(smokers: 27.6 +/- 8.0 mumol/l, control subjects: 34.0 +/- 8.7 mumol/l). However, percentage change of flow-mediated vasodilation during reactive hyperemia in the young smokers was significantly smaller than that in the control subjects(4.8 +/- 2.7%, 9.1 +/- 5.3%, respectively, p < 0.05). Moreover, delta NOx during reactive hyperemia in the smokers was significantly smaller than that in the control subjects(388.8 +/- 90.2%, 738.0 +/- 284.5%, respectively, p < 0.05). CONCLUSIONS: The impaired response to reactive hyperemia in young smokers might be associated with decreases in flow-dependent NO production.

Adult↗
PubMed2000

Characterization of human herpesvirus 7 U27 gene product and identification of its nuclear localization signal.

A monoclonal antibody, 5H4, that recognizes human herpesvirus 7 (HHV-7) was used in Western analysis to probe HHV-7-infected SupT1 cells. This antibody recognizes a 40-kDa virus-specific polypeptide that is expressed in the absence of viral DNA synthesis. By screening a lambdagt11 HHV-7 cDNA library, the gene encoding the protein was identified as the U27 open reading frame previously reported [J. Virol. (1996) 70, 5975-5989]. Immunofluorescent studies showed a punctate nuclear localization of the protein in both HHV-7-infected cells and transfected cells. A computer program predicted two classic nuclear localization signals (NLSs) in the middle and C-terminal regions of the protein. A C-terminal deletion mutant of the protein could not enter the nucleus, whereas green fluorescent protein or maltose binding protein fused to the C-terminal region of the protein was transported into the nucleus. These findings demonstrate that the predicted C-terminal, but not middle, NLS of the protein actually function as NLS. In addition, nuclear transport of a maltose binding protein-fusion protein containing the C-terminal NLS of the U27 protein was inhibited by both wheat germ agglutinin and a Q69L Ran-GTP mutant, indicating that the U27 protein is transported into the nucleus from the cytoplasm by means of classic nuclear transport machinery. Interestingly, this NLS motif is highly conserved at the C-termini of all herpesvirus DNA polymerase processivity factors that have been examined.

Amino Acid Sequence↗
PubMed2000

Differential interaction of CrkII adaptor protein with platelet-derived growth factor alpha- and beta-receptors is determined by its internal tyrosine phosphorylation.

CrkII is an intracellular adaptor protein involved in signal transduction by various growth factors. Activation of PDGF alpha-receptor resulted in its association with CrkII in vivo. In contrast, binding of CrkII to the PDGF beta-receptor was negligible, despite its becoming prominently phosphorylated. Bacterially expressed GST-CrkII SH2 domain specifically bound to Tyr-762 and Tyr-771 in the activated PDGF alpha- and beta- receptors, respectively. GST fusion protein of full-length CrkII also bound to the activated PDGF beta-receptor. However, tyrosine phosphorylation of GST-CrkII diminished its binding to the beta-receptor. CrkI, a truncated version of CrkII lacking the phosphorylatable tyrosine residue, could bind to both PDGF alpha- and beta-receptors in vivo. In conclusion, tyrosine phosphorylation of CrkII negatively affects its binding to the PDGF receptors. The differential binding of CrkII to the PDGF alpha- and beta- receptors may be a rationale for functional diversity between the two receptors.

Animals↗
PubMed2000

Diagnostic usefulness of diffusion-weighted magnetic resonance imaging in influenza-associated acute encephalopathy or encephalitis.

A magnetic resonance imaging (MRI) study was performed for a 20-month-old girl with an influenza type A infection who presented acute encephalopathy. Conventional MRI performed 8 days after the onset of encephalopathy, including T1-weighted, T2-weighted, and fluid-attenuated inversion recovery imaging, revealed only vague lesions in the right frontal, temporal, and parietal lobes. In contrast, diffusion-weighted imaging (DWI) then demonstrated the lesions much more intensively. On the 26th day, the lesions previously observed on DWI had become less discernible. The hyperintensity observed on DWI might reflect cytotoxic edema. Thus, DWI may be useful for evaluation of acute influenzal encephalopathy/encephalitis.

Acute Disease↗
PubMed2000

Microcapsulated parathyroid tissue in vitro.

Ideally, microcapsules will make it possible to transplant parathyroid tissue for allo- and xenotransplantation in hypoparathyroid patients. In this study, parathyroid tissues capsulated by polyelectrolyte complex were evaluated in vitro. Hormone secretion ability was significantly (P < 0.001) greater in sediment than in supernatant. There was no difference in hormone secretion ability between the parathyroid tissue thawed at room temperature and the tissue thawed in a bath at 37 degrees C. Both non-capsulated and capsulated parathyroid tissues were incubated for three weeks. The ability of capsulated parathyroid to secrete hormones in vitro was reduced gradually and disappeared within three weeks. There are still several problems to be solved before the clinical application of parathyroid allotransplantation using microcapsulation.

Cryopreservation↗
PubMed2000

Chronic inhibition of nitric oxide synthesis in rats increases aortic superoxide anion production via the action of angiotensin II.

OBJECTIVE: Chronic inhibition of nitric oxide (NO) synthesis by Nomega-nitro-L-arginine methyl ester (L-NAME) increases vascular tissue angiotensin II activity and oxidative stress in animals by incompletely understood mechanisms. In a rat model, we investigated the role of local angiotensin II activity in the pathogenesis of increased oxidative stress. DESIGN: We studied the aortas of control rats and others receiving L-NAME or L-NAME plus an angiotensin II type 1 receptor antagonist (CS-866). RESULTS: Administration of L-NAME for 7 days significantly increased superoxide anion (O2-) and both immunoreactivity and electrophoretically demonstrable activity of redox-sensitive transcription factors (NF-kappaB and AP-1). Treatment with the angiotensin II type 1 receptor antagonist prevented all of the above changes. The observed effects of the type 1 receptor antagonist was independent of the L-NAME-induced arterial hypertension. CONCLUSIONS: These findings suggest that chronic inhibition of NO synthesis may increase vascular oxidative stress and oxidative stress-sensitive signals via the action of angiotensin II mediated via type 1 receptors.

Angiotensin II↗
PubMed2000

Enhanced expression of osteopontin by high glucose. Involvement of osteopontin in diabetic macroangiopathy.

Atherosclerotic vascular disease is a major complication of diabetic patients. Osteopontin has recently been implicated in the development of atherosclerosis. In the present study, we have investigated the effects of high glucose on expression of osteopontin in cultured rat aortic smooth muscle cells. High concentrations of glucose increased osteopontin secretion from the cells, and the increased secretion was completely inhibited by an inhibitor of protein kinase C, GF109203X. Northern blot analysis confirmed the enhanced effect of glucose on expression of osteopontin mRNA. Promoter activity of osteopontin, measured using the osteopontin promoter/luciferase expression vector system, was increased by high glucose, and the enhanced effect was completely inhibited by GF109203X. Glucosamine also increased the promoter activity of osteopontin. Azaserine, an inhibitor of glutamine:fructose-6-phosphate amidotransferase, the key enzyme of the hexosamine pathway, profoundly inhibited high glucose-mediated increase in the promoter activity. Taken together, these data indicate that high glucose enhances the expression of osteopontin at the transcriptional level possibly through the activation of protein kinase C as well as the hexosamine pathway. Our results suggest that osteopontin could play a role in the development of diabetic vascular complications.

Animals↗
PubMed2000

Enhanced expression of osteopontin in human diabetic artery and analysis of its functional role in accelerated atherogenesis.

We have previously reported that high glucose stimulates osteopontin (OPN) expression through protein kinase C-dependent pathways as well as hexosamine pathways in cultured rat aortic smooth muscle cells. The finding prompted us to study in vivo expression of OPN in diabetes mellitus. In the present study, we found by immunohistochemistry that medial layers of the carotid arteries of streptozotocin-induced diabetic rats and the forearm arteries of diabetic patients stained positively for OPN antibodies, whereas the staining from arteries of control rats and nondiabetic patients was negative. We also found that OPN stimulated the migration and enhanced platelet-derived growth factor (PDGF)-mediated DNA synthesis of cultured rat aortic smooth muscle cells. OPN and PDGF synergistically activated focal adhesion kinase as well as extracellular signal-regulated kinase; this finding seems to explain the OPN-induced enhancement of PDGF-mediated DNA synthesis. Taken together, our present results raise a possibility that OPN plays a role in the development of diabetic vascular complications.

Adult↗
PubMed2000

Interpolation of missing part of human follicle border on ultrasonic B-mode image by iterative revision.

In clinical infertility treatments, assessment of ovarian follicle growth by ultrasonography is important. In order to measure the geometrical characteristics of the human follicle, such as the area of the cross-sectional image and the volume inside the follicle, a method based on manual tracing of the follicle contour from the ultrasonic B mode image is widely used. However, the observable ultrasonic B mode images are sometimes imperfect and some parts of the follicle border are missing due to the existence of the acoustic shadow. In this paper, a method that interpolates the missing part of the follicle border from the known part is proposed. This method uses a priori information of the follicle, which is usually known in actual cases: (1) the follicle's surface is so smooth that its border is assumed to be a smooth closed curve; and (2) the position of the follicle's center is roughly predicted in advance in the ultrasonic B-mode image. In the proposed method, the missing part of the human follicle border is interpolated from the known part by applying an iterative revision so as to satisfy the smoothness condition of the follicle. This method is also applied to three-dimensional image reconstruction of the human follicle.

Algorithms↗
PubMed2000

Inhibition of in vitro fertilization of mouse gametes by sulfated sialic acid polymers.

The effect of sialic acid (N-acetyl neuraminic acid), sialic acid dimer, sialic acid polymers (colominic acid) and sulfated colominic acid on the activity of hyaluronidase, on the dispersion of cumulus cells by mouse sperm and on in vitro mouse fertilization (sperm penetration of zona pellucida) were evaluated. Bovine testicular hyaluronidase activity was significantly inhibited by colominic acid and sulfated colominic acid, but not by sialic acid and its dimer. The dispersion of cumulus cells from eggs by mouse sperm was also inhibited by colominic acid and sulfated colominic acid. In vitro fertilization of mouse gametes was inhibited by sulfated colominic acid. The IC50 value of sulfated colominic acid-induced inhibition of fertilization was 0.3 mg/ml (ca. 0.9 mM). The value changed from 0.9 mM for cumulus-surrounded egg to 1.5 mM for cumulus free-egg. On the other hand, colominic acid showed little or no inhibitory effect on mouse in vitro fertilization at 0.5 mg/ml (ca. 1.6 mM). This antifertility activity by sulfated colominic acid did not appear to be due to an effect on sperm motility or on the oocytes. These results suggest that (1) the cumulus cells surrounding the eggs were dispersed by sperm hyaluronidase, (2) hyaluronidase was inhibited by colominic acid and by sulfated colominic acid, (3) sulfated colominic acid inhibits sperm penetration of zona pellucida by the inhibition of hyaluronidase and/or some enzymes required for mouse gametes fertilization.

Animals↗
PubMed2000

Decrease of nitric oxide end-products during coronary circulation reflects elevated basal coronary artery tone in patients with vasospastic angina.

The aim of this study was to investigate the role of nitric oxide (NO) in the coronary circulation and its relation to basal coronary artery tone in patients with vasospastic angina (VSA). We evaluated the level of nitric oxide end-products (NOx; nitrite + nitrate) in coronary circulation blood using an HPLC-Griess system for nine patients with VSA and nine control patients. All of the patients with VSA experienced focal spasm in the proximal to middle segments of the left anterior descending coronary artery (LAD) in response to intracoronary injection of ergonovine maleate. The luminal diameter of the coronary artery was measured in each patient by quantitative coronary arteriography. Blood samples for NOx measurement were obtained from the coronary sinus (NOxV) and the ostium of the left coronary artery (NOxA). The NOx difference, calculated from the coronary venous-arterial difference in NOx, was close to zero for the control patients whereas it was clearly negative for the patients with VSA. In addition, the NOx difference in the patients with VSA showed a negative correlation with basal coronary artery tone (r = -0.91, p < 0.01) and a positive correlation with the dose of ergonovine required for spasm provocation (r = 0.77, p < 0.05). These results indicate that increased basal coronary artery tone and higher susceptibility to ergonovine in patients with VSA would be a consequence of coronary endothelial dysfunction as is indicated by NOx.

Adult↗
PubMed2000

An infant with precursor natural killer (NK) cell leukemia successfully treated with an unrelated cord blood transplantation.

Here we report a case with precursor natural killer (NK) cell leukemia successfully treated with an unrelated cord blood transplantation. A 7-month-old Japanese boy was diagnosed to have NK cell leukemia based on the existence of abnormal cells in the bone marrow with the phenotype of CD3(-) /CD4(+) /CD7(-) /CD8(-) /CD16(-) /CD33(+) /CD34(-) /CD56(+) /HLA-DR(+) /NKB1(+) / CD94(+). The leukemic cells showed few azurophilic granules in the cytoplasm and weak cytotoxic activity. Although he presented with a huge mass occupying the bilateral paranasal sinuses and hepatosplenomegaly, he achieved complete remission by the conventional chemotherapeutic regimen for acute myelogenous leukemia, followed by an unrelated cord blood transplantation. He has remained in complete remission for 14 months posttransplant. To our knowledge, this is the youngest reported case with precursor NK cell leukemia; cord blood transplantation may thus be the treatment of choice for this disease.

Disease-Free Survival↗
PubMed1999

Enhanced expression of osteopontin by high glucose in cultured rat aortic smooth muscle cells.

Atherosclerotic vascular disease is a major complication of diabetic patients, and osteopontin has recently been implicated in the development of atherosclerosis. In the present study, we have investigated the effects of high glucose on expression of osteopontin in cultured rat aortic smooth muscle cells. High concentrations of glucose increased osteopontin secretion from the cells, and the increased secretion was completely inhibited by an inhibitor of protein kinase C, GF109203X. Northern blot analysis confirmed the enhanced effect of glucose on expression of osteopontin mRNA. Promoter activity of osteopontin, measured using the osteopontin promoter/luciferase expression vector system, was increased by high glucose, and the enhanced effect was completely inhibited by GF109203X. Glucosamine also increased the promoter activity of osteopontin, and azaserine, an inhibitor of glutamine:fructose-6-phosphate amidotransferase (the key enzyme of the hexosamine pathway), profoundly inhibited high glucose-mediated increase in the promoter activity. Taken together, these data indicate that high glucose enhances the expression of osteopontin at the transcriptional level possibly through the activation of protein kinase C as well as the hexosamine pathway. Our results suggest that osteopontin could play a role in the development of diabetic vascular complications.

Animals↗
PubMed1999

Platelet-derived growth factor activates p38 mitogen-activated protein kinase through a Ras-dependent pathway that is important for actin reorganization and cell migration.

Members of the mitogen activated protein (MAP) kinase family, extracellular signal-regulated kinase, stress-activated protein kinase-1/c-Jun NH2-terminal kinase, and p38, are central elements that transduce the signal generated by growth factors, cytokines, and stressing agents. It is well known that the platelet-derived growth factor (PDGF) activates extracellular signal-regulated kinase, which leads to cellular mitogenic response. On the other hand, the role of the other MAP kinases in mediating the cellular function of PDGF remains unclear. In the present study, we have investigated the functional role of the other MAP kinases in PDGF-mediated cellular responses. We show that ligand stimulation of PDGF receptors leads to the activation of p38 but not stress-activated protein kinase-1/c-Jun NH2-terminal kinase. Experiments using a specific inhibitor of p38, SB203580, show that the activation of p38 is required for PDGF-induced cell motility responses such as cell migration and actin reorganization but not required for PDGF-stimulated DNA synthesis. Analyses of tyrosine residue-mutated PDGF receptors show that Src homology 2 domain-containing proteins including Src family kinases, phosphatidylinositol 3-kinase, the GTPase-activating protein of Ras, the Src homology 2 domain-containing phosphatase SHP-2, phospholipase C-gamma, and Crk do not play a major role in mediating the PDGF-induced activation of p38. Finally, the expression of dominant-negative Ras but not dominant-negative Rac inhibited p38 activation by PDGF, suggesting that Ras is a potent mediator in the p38 activation pathway downstream of PDGF receptors. Taken together, our present study proposes the existence of a Ras-dependent pathway for the activation of p38, which is important for cell motility responses elicited by PDGF stimulation.

Actins↗