PubMed Health⌕ Search

Biomedical subjects

Tomoki Hashimoto

Publications and source records attributed to Tomoki Hashimoto.

At least 19 recordsLinked to original sources
PubMed2006

MMP-9 expression is associated with leukocytic but not endothelial markers in brain arteriovenous malformations.

Brain arteriovenous malformations (BAVM) have high matrix metalloproteinase-9 (MMP-9) expression, the source of which is unclear. We hypothesized MMP-9 production might be due to inflammation in BAVM. Compared to control brain tissues (n = 5), BAVM tissue (n = 139) had a higher expression (by ELISA) of myeloperoxidase (MPO) (193 +/- 189 vs. 6 +/- 3, ng/mg, P < .001), MMP-9 (28 +/- 32 vs. 0.7 +/- 0.6, ng/mg, P < .001), and IL-6 (102 +/- 218 vs. 0.1 +/- 0.1, pg/mg, P < .001), but not eNOS (114 +/- 87 vs. 65 +/- 9, pg/mg, P = .09). MMP-9 expression in BAVM highly correlated with myeloperoxidase (R2 = .76, P < .001), as well as with IL-6 (R2 = .32, P < .001). In contrast, MMP-9 in BAVM poorly correlated with the endothelial marker, eNOS (R2 = .03, P = .05), and CD31 (R2 = .004, P = .57). Compared to non-embolized patients (n = 46), patients with pre-operative embolization (n = 93) had higher levels of myeloperoxidase (236 +/- 205 vs. 106 +/- 108, ng/mg, P < .001) and MMP-9 (33 +/- 35 vs. 16 +/- 20, ng/mg, P < .001), however the correlation between MMP-9 and myeloperoxidase was equally strong for both groups (R2 = .69, n = 93, P < .001, for both). MMP-9 expression correlated with the lipocalin-MMP-9 complex, suggesting neutrophils as the MMP-9 source. MPO co-localized with majority of MMP-9 signal by immunohistochemistry. Our data suggest that inflammation is a prominent feature of BAVM lesional phenotype, and neutrophils appear to be a major source of MMP-9 in these lesions.

Adult↗
PubMed2006

Intracranial aneurysms: links among inflammation, hemodynamics and vascular remodeling.

Abnormal vascular remodeling mediated by inflammatory cells has been identified as a key pathologic component of various vascular diseases, including abdominal aortic aneurysms, brain arteriovenous malformations and atherosclerosis. Based on findings from observational studies that analysed human intracranial aneurysms and experimental studies that utilized animal models, an emerging concept suggests that a key component of the pathophysiology of intracranial aneurysms is sustained abnormal vascular remodeling coupled with inflammation. This concept may provide a new treatment strategy to utilize agents to inhibit inflammation or cytokines produced by inflammatory cells such as matrix metalloproteinases. Such an approach would aim to stabilize these vascular lesions and prevent future expansion or rupture.

Animals↗
PubMed2005

Suppression of MMP-9 by doxycycline in brain arteriovenous malformations.

BACKGROUND: The primary aim of this study is to demonstrate the feasibility of utilizing doxycycline to suppress matrix metalloproteinase-9 (MMP-9) in brain arteriovenous malformations (AVMs). METHODS: Ex-vivo treatment of AVM tissues: Intact AVM tissues were treated with doxycycline for 48 hours. Active and total MMP-9 in the medium were measured. Pilot trial: AVM patients received either doxycycline (100 mg) or placebo twice a day for one week prior to AVM resection. Active and total MMP-9 in BVM tissues were measured. RESULTS: Ex-vivo treatment of AVM tissues: Doxycycline at 10 and 100 microg/ml significantly decreased MMP-9 levels in AVM tissues ex-vivo (total: control vs 10 vs 100 microg/ml = 100 +/- 6 vs 60 +/- 16 vs 61 +/- 9%; active: 100 +/- 8 vs 48 +/- 16 vs 59 +/- 10%). Pilot trial: 10 patients received doxycycline, and 4 patients received placebo. There was a trend for both MMP-9 levels to be lower in the doxycycline group than in the placebo group (total: 2.18 +/- 1.94 vs 3.26 +/- 3.58, P = .50; active: 0.48 +/- 0.48 vs 0.95 +/- 1.01 ng/100 microg protein, P = .25). CONCLUSIONS: A clinically relevant concentration of doxycycline decreased MMP-9 in ex-vivo AVM tissues. Furthermore, there was a trend that oral doxycycline for as short as one week resulted in a decrease in MMP-9 in AVM tissues. Further studies are warranted to justify a clinical trial to test effects of doxycycline on MMP-9 expression in AVM tissues.

Adult↗
PubMed2005

Angiogenesis in the brain during development: the effects of vascular endothelial growth factor and angiopoietin-2 in an animal model.

OBJECT: The goal of this study was to examine the roles of vascular endothelial growth factor (VEGF) and angiopoietin-2 (Ang-2) in the formation of blood vessels in the brain in a developmental animal model not routinely used for such a study. METHODS: Either VEGF, Ang-2, or a combination of the two factors were injected into the optic tectum of 4-day-old quail embryos. Immunohistochemical analysis and laser confocal microscopy were used to observe the effects on endothelial cells in the brain. Vascular endothelial growth factor and Ang-2 had very different effects on the development of blood vessels; the former caused expansion and the latter retraction of these vessels. Treatment with a combination of VEGF and Ang-2 caused retroorbital or intraventricular hemorrhage, and brain blood vessels appeared enlarged and dysmorphic, with dramatically extended filopodia. CONCLUSIONS: Some of these observations may provide insight into how one may develop a better model of brain arteriovenous malformations.

Angiopoietin-2↗
PubMed2005

Coexpression of angiogenic factors in brain arteriovenous malformations.

OBJECTIVE: Brain arteriovenous malformations (BAVMs) are structurally unstable blood vessels that display an angiogenic phenotype, possibly maintained by concerted effects of key angiogenic factors. Therefore, we hypothesized that there are close correlations among key angiogenic factors in BAVMs and that levels of key angiogenic factors are associated with BAVM clinical characteristics that are linked with vascular instability. METHODS: We measured the expression of angiopoietin-2 (Ang-2), matrix metalloproteinase-9, vascular endothelial growth factor (VEGF), and platelet-derived growth factor-AA and -BB by use of enzyme-linked immunosorbent assay in 27 BAVM surgical specimens. Tissues were also collected from 14 structurally normal brain specimens obtained during epilepsy surgery. RESULTS: Ang-2, VEGF, and matrix metalloproteinase-9 were highly expressed in BAVM samples (11.9 +/- 15.5 ng/mg protein, 137 +/- 102 pg/mg protein, and 379 +/- 455 pg/mg protein, respectively). Platelet-derived growth factor-BB was detectable in 7 of 21 BAVM samples. There were close correlations between Ang-2 and VEGF (R2 = 0.79). Higher Ang-2 and VEGF levels seemed to be associated with draining vein characteristics linked with BAVM hemorrhage but not with feeding artery pressure or BAVM size. In the structurally normal brain specimens, levels of Ang-2, VEGF, and matrix metalloproteinase-9 were low (0.8 +/- 2.3 ng/mg protein, 38 +/- 25 pg/mg protein, and 52 +/- 43 pg/mg protein, respectively). CONCLUSION: There were close correlations among angiogenic factors in BAVMs. Concerted effects of angiogenic factors may maintain the angiogenic phenotype in BAVMs and thereby determine the clinical course of BAVMs.

Angiopoietin-2↗
PubMed2004

Polymorphisms in genes involved in inflammatory and angiogenic pathways and the risk of hemorrhagic presentation of brain arteriovenous malformations.

BACKGROUND AND PURPOSE: Accurate estimates of intracranial hemorrhage (ICH) risk in patients harboring brain arteriovenous malformation (BAVM) are needed to evaluate interventional strategies and to help guide clinical management. Identification of genetic polymorphisms associated with ICH would facilitate risk stratification in BAVM patients. METHODS: We identified patients with BAVM and documented clinical presentation, demographic data, venous drainage pattern, and BAVM size. Patients were genotyped for 5 polymorphisms in 3 inflammatory cytokine genes, and 9 polymorphisms in 5 angiogenesis-related genes. Association of genotype with risk of hemorrhagic BAVM presentation was evaluated using logistic regression analysis. RESULTS: We genotyped 180 patients with BAVM (53% female, 57% white, mean age at diagnosis 35+/-17 years, 41% presenting with ICH). BAVM patients homozygous for the interleukin 6 (IL6)-174G allele had a greater risk of ICH presentation (OR, 2.62, P=0.003) than IL6-174C carriers. In a multivariate logistic regression model, IL6-174G>C genotype, small BAVM size, and exclusively deep venous drainage were independent predictors of ICH presentation. A similar univariate trend was noted for the TNFalpha-308 GG genotype (P=0.055). The other polymorphisms genotyped were not associated with ICH. CONCLUSIONS: A polymorphism in the inflammatory cytokine IL6, but not polymorphisms in angiogenesis-related genes, was associated with ICH presentation of BAVM. Further studies are needed to define the role of inflammatory cytokines in the pathogenesis of BAVM hemorrhage.

Adult↗
PubMed2004

Doxycycline suppresses cerebral matrix metalloproteinase-9 and angiogenesis induced by focal hyperstimulation of vascular endothelial growth factor in a mouse model.

BACKGROUND AND PURPOSE: A number of central nervous system (CNS) disorders are associated with abnormalities in or activation of angiogenesis, including vascular malformations. To test the hypothesis that the nonspecific matrix metalloproteinase (MMP) inhibitor, doxycycline, suppresses vascular endothelial growth factor (VEGF)-induced cerebral angiogenesis through inhibition of MMPs, we used a mouse model with enhanced cerebral angiogenesis induced by focal hyperstimulation of VEGF from adenovirus DNA (AdVEGF) transduction. METHODS: The time course study of MMP activity was performed at 7 and 14 days after AdVEGF transduction. MMP activity and expression were examined by zymography and immunohistochemistry, respectively. As an index of cerebral angiogenesis, microvessel counting was performed in the brains of 3 groups of mice (n=6): (1) control; (2) AdVEGF only; and (3) AdVEGF plus doxycycline (30 mg/kg per day). RESULTS: Brain MMP-9 activities increased 4-fold (883+/-137 versus 179+/-179; 1-sided P<0.001) at 7 days after AdVEGF transduction. VEGF transduction increased vessel counts by 19% (255+/-27 versus 215+/-15, 1-sided P<0.01). Doxycycline treatment decreased MMP-9 activity (89+/-72 versus 883+/-137; 1-sided P<0.001) and cerebral microvessel number (231+/-17 versus 255+/-27; 1-sided P<0.05). CONCLUSIONS: Doxycycline is effective in decreasing stimulated cerebral MMP-9 activity and parenchymal angiogenesis. The decrease in MMP-9 activity is associated with decreased microvessel counts. Brain pathophysiological processes that involve abnormally enhanced angiogenesis may be amenable to manipulation by MMP inhibitors, including tetracycline derivatives.

Adenoviridae↗
PubMed2004

Participation of PI3K and ERK1/2 pathways are required for human brain vascular smooth muscle cell migration.

Human brain vascular smooth muscle cell (HBVSMC) migration contributes to angiogenesis and several pathological processes in the brain. However, the molecular mechanism of angiogenesis, in which smooth muscle cell contributes, remains unclear. Our study investigates the role of vascular endothelial growth factor (VEGF) in the HBVSMC migration and elucidates the chemotactic signaling pathway mediating this action. We used the in vitro 'scratch' wound method to detect the HBVSMC migration. VEGF(165) (1-40ng/ml) induced the HBVSMC migration in a dose-dependent manner (P<0.05). VEGF(165) does not induce HBVSMC proliferation. Wortmannin, a specific phosphatidylinositol 3-kinase (PI3K) inhibitor, significantly inhibited serine/threonine kinase Akt/protein kinase B (PKB) phosphorylation and reduced HBVSMC migration into the wound edge following VEGF(165) stimulation (P<0.05). PD98059, an extracellular signal-regulated kinase 1/2 (ERK1/2) inhibitor, also significantly inhibited ERK1/2 phosphorylation and reduced the numbers of SMC migration. Parallel distance measurement showed that VEGF(165) induced HBVSMC migration significantly reduced due to inhibition of PI3K or ERK1/2 phosphorylation (P<0.05). Our results demonstrate that VEGF(165) could induce HBVSMC migration but not proliferation in vitro. Inhibiting Akt/PKB or ERK1/2 phosphorylation could reduce VEGF(165) induced HBVSMC migration. We provide the first evidence that activation of PI3K or ERK1/2 pathways are a crucial event in VEGF(165) mediated signal transduction leading to HBVSMC migration.

Androstadienes↗
PubMed2004

Physiologic monitoring and anesthesia considerations in acute ischemic stroke.

Acute ischemic stroke is considered a neurologic emergency. The perioperative anesthesia management of acute ischemic stroke is challenging owing to the dynamic pathophysiology of the disease itself and the patients' comorbid factors and conditions. Herein, the authors review preoperative assessment, intraoperative and postoperative physiologic monitoring, and anesthesia management, with a focus on the control of the cerebrovascular and cardiovascular circulations. Issues specific to anesthesia monitoring and management in the radiology suite are emphasized.

Acute Disease↗
PubMed2004

Vascular endothelial growth factor induces abnormal microvasculature in the endoglin heterozygous mouse brain.

Hereditary hemorrhagic telangiectasia (HHT), associated with brain arteriovenous malformations, is caused by a loss of function mutation in either the endoglin (HHT1) or activin receptor-like kinase 1 gene (ALK-1, HHT2). Endoglin heterozygous (Eng+/-)mice have been proposed as a disease model. To better understand the role of endoglin in vascular malformation development, we examined the effect of vascular endothelial growth factor (VEGF) hyperstimulation on microvessels in adult endoglin heterozygous (Eng+/-) mice using an adenoviral vector to deliver recombinant human VEGF165 cDNA (AdhVEGF) into basal ganglia. VEGF expression was increased in AdhVEGF mice compared with the AdlacZ and saline group (P < 0.05) and localized to multiple cell types (neurons, astrocytes, endothelial cells, and smooth muscle cells) by double-labeled immunostaining. VEGF overexpression increased microvessel count for up to 4 weeks in both the Eng+/+ and Eng+/- groups (Eng+/+ 185 +/- 14 vs. Eng+/- 201 +/- 10 microvessels/mm2). Confocal microscopic examination revealed grossly abnormal microvessels in eight of nine Eng+/- mouse brains compared with zero of nine in Eng+/+ mice (P < 0.05). Abnormal microvessels featured enlargement, clustering, twist, or spirals. VEGF receptor Flk-1 and TGF-beta receptor 1 (T beta R1) expression were reduced in the Eng+/- mouse brain compared with control. Excessive VEGF stimulation may play a pivotal role in the initiation and development of brain vessel malformations in states of relative endoglin insufficiency in adulthood. These observations are relevant to our general understanding of the maintenance of vascular integrity.

Animals↗
PubMed2004

Retroviral delivery of homeobox D3 gene induces cerebral angiogenesis in mice.

Angiogenesis is regulated by concerted actions of angiogenic and angiostatic factors. Homeobox D3 gene (HOXD3) is a potent proangiogenic transcription factor that promotes angiogenesis by modulating the expression of matrix-degrading proteinases, integrins, and extracellular matrix components. Application of HOXD3 can promote angiogenesis in the skin, but its role in other vascular beds has not been examined. The authors examined HOXD3 expression in human brain vessels by in situ hybridization. Although little or no HOXD3 mRNA was detected in normal brain vessels, increased levels of HOXD3 and its target gene, alpha V beta 3, were found in angiogenic vessels in human brain arteriovenous malformations. The authors further investigated whether HOXD3 plays a role in cerebral angiogenesis in a murine model. Expression of HOXD3 in mouse brain was achieved through retroviral vector-mediated HOXD3 gene transfer. HOXD3 expression lead to a significant induction of cerebral angiogenesis as shown by quantitative microvessel counting (HOXD3: 241 +/- 19 vessels/mm2 vs. saline: 150 +/- 14 vessels/mm2, P < 0.05). The data also showed that focal cerebral blood flow was increased in the angiogenic region with less vascular leakage. Moreover, expression of HOXD3 led to an increase in the expression of a direct downstream target gene alpha V beta 3 integrin. The data suggest that HOXD3 may play an important role in regulating cerebral angiogenesis, and that gene transfer of HOXD3 may provide a novel and potent means to stimulate angiogenesis.

Animals↗
PubMed2004

Gene microarray analysis of human brain arteriovenous malformations.

OBJECTIVE: Human brain arteriovenous malformations (BAVMs) display abnormal expression of various angiogenesis-related genes and their products. We examined gene expression patterns in BAVMs by the gene microarray technique. METHODS: We analyzed BAVM and control brain samples obtained by temporal lobectomy for medically intractable seizure by Affymetrix Human Gene Set U95Av2 (Affymetrix, Inc., Santa Clara, CA). The gene microarray data were compared with new and previously published data that used conventional molecular biology techniques. RESULTS: We analyzed six BAVM and five control brain samples. From 12,625 gene probes assayed, 1781 gene probes showed differential expression between BAVMs and controls. BAVM samples had a gene expression pattern that was distinct from those of control brain samples. Increased messenger ribonucleic acid expression of vascular endothelial growth factor A was accompanied by increased expression of its protein product. A majority of the gene data was in agreement with previously published data. The gene microarray data generated a new testable hypothesis regarding integrin, and we found increased expression of integrin alphavbeta3 protein in BAVMs. CONCLUSION: The gene expression pattern of BAVMs was distinct from those of control brain samples. We verified the gene microarray data by demonstrating that increased gene expression levels for angiogenesis-related molecules were accompanied by increased levels of their protein product expression. The gene microarray technique may be a useful tool to study multiple pathways simultaneously in BAVM specimens.

Adolescent↗
PubMed2004

The transgenic arteriovenous fistula in the rat: an experimental model of gene therapy for brain arteriovenous malformations.

OBJECTIVE: To introduce the transgenic arteriovenous fistula model in the rat, constructed by interposing mouse aorta in a fistula between the common carotid artery and external jugular vein in a nude rat, and to describe the model's technical feasibility, long-term patency, and expression of reporter genes. METHODS: Carotid-jugular fistulae were surgically created in 112 rats. In 25 immunodeficient nude rats, wild-type mouse thoracic aorta (TAo) was interposed in the fistula; in 10 immunocompetent rats, TAo was interposed; in 19 nude rats, transgenic TAo with reporter genes for beta-galactosidase or green fluorescent protein was interposed; in 18 nude rats, wild-type mouse ascending aorta was interposed; and in 40 rats, a simple fistula was constructed without an interpositional graft. Host tolerance and graft viability were analyzed by histopathology and immunohistochemistry for CD31 (mouse endothelial cell marker), endothelial nitric oxide synthase, smooth muscle actin, fibronectin, beta-galactosidase, and green fluorescent protein. RESULTS: The transgenic arteriovenous fistula was technically feasible and immunologically tolerated in nude rats but not in immunocompetent rats. The overall angiographic patency rate was 41% with TAo grafts and 56% with ascending aorta grafts, both lower than the 98% patency rate in fistulae with a single anastomosis and no interpositional graft. Mouse endothelium survived on the graft for 3 months according to CD31 staining, but longer survival by transgenic smooth muscle cells resulted in continued expression of beta-galactosidase for 6 months and green fluorescent protein for 4 months. Endothelium and smooth muscle in the fistula were functional, with normal expression of endothelial nitric oxide synthase as well as smooth muscle actin and fibronectin, respectively. CONCLUSION: The transgenic arteriovenous fistula model enhances other carotid-jugular fistula models by integrating transgenic tissue, thereby creating an experimental system for investigating the molecular biology of and gene therapies for arteriovenous malformations.

Animals↗
PubMed2003

Abnormal expression of matrix metalloproteinases and tissue inhibitors of metalloproteinases in brain arteriovenous malformations.

BACKGROUND AND PURPOSE: Excessive degradation of the vascular matrix by matrix metalloproteinases (MMPs) can lead to structural instability of vessels. In this study we examined the expression of MMPs and tissue inhibitors of metalloproteinases (TIMPs) in brain arteriovenous malformations (BAVMs). METHODS: We performed gelatin zymography for MMPs and Western blot for MMP-9, MMP-2, TIMP-1, TIMP-2, TIMP-3, and TIMP-4. MMP-9 expression was localized by immunohistochemistry. RESULTS: We analyzed 37 BAVM specimens and 9 control brain specimens from epilepsy surgery. Thirty-two BAVM patients had embolization treatment before resection. Eighteen BAVM patients had a history of hemorrhage from BAVMs. Neither MMP-2 nor TIMP-2 was detected in BAVMs or control brain specimens. Compared with control brain samples, BAVM samples had higher levels of total MMP-9, active MMP-9, pro-MMP-9, TIMP-1, and TIMP-3. TIMP-4 levels were higher in the control brain than in BAVM specimens. MMP-9 was localized to the endothelial cell/peri-endothelial cell layer and infiltrating neutrophils of BAVMs. BAVMs with venous stenosis >or=50% had higher expression of MMP-9 than BAVMs with venous stenosis <50%. There was no apparent association between total MMP-9, pro-MMP-9, or active MMP-9 levels and (1) feeding artery pressure, (2) pattern of draining vein (exclusively deep venous drainage versus any superficial drainage), and (3) BAVM size. CONCLUSIONS: We found increased levels of MMP-9 and TIMPs in BAVMs. Abnormal balance of MMP-9 and TIMPs may contribute to vascular instability of BAVMs.

Adult↗
PubMed2003

Induction of focal angiogenesis through adenoviral vector mediated vascular endothelial cell growth factor gene transfer in the mature mouse brain.

Vascular endothelial growth factor (VEGF) is a potent endothelial cell mitogen and morphogen, which stimulates angiogenesis in a wide variety of tissues and lesions in vivo. In this study, we applied adenoviral vector delivered human VEGF165 cDNA to develop focal non-tumor angiogenesis in the mature mouse brain. Seventy-two adult CD-1 mice underwent Ad h VEGF, Ad lacZ, and saline injection for up to fourweeks. An adenoviral suspension containing 1 x 10(9) particles was injected stereotactically into the right hemisphere of the brain. The results showed that VEGF expression was increased in the Ad h VEGF transduced mice compared to Ad lacZ or saline injected mice ( P < 0.05). VEGF-positive cells were mainly located in the injection hemisphere of Ad h VEGF transduced mice. Quantitative vessel counting showed that microvessels in the Ad h VEGF transduced mice increased following 2 weeks of Ad h VEGF gene transfer compared to the other two groups (Ad h VEGF:241 +/- 19 vs. Ad lacZ :148 +/- 17 and Saline:150 +/- 14 vessels/mm2, P < 0.05). Morphology showed typical angiogenic changes. PCNA-positive staining confirmed these microvessels were actively proliferating. Our study demonstrates that Ad h VEGF-induced VEGF hyper-stimulation causes focal angiogenesis in the mature mouse brain. This novel method of inducing in vivo brain focal angiogenesis provides an opportunity to study the molecular mechanisms independent of the confounding effects of upstream inciting stimuli such as ischemia or tumor.

Adenoviridae↗
PubMed2002

Interventional neuroradiology--anesthetic considerations.

Interventional neuroradiologic procedure represents treatment of central nervous system disease by endovascular access for the purpose of delivering therapeutic agents, including both drugs and devices. For optimal anesthetic management, anesthesiologists should be familiar with specific radiological procedures and their potential complications. This article provides a brief overview of special considerations in conducting general anesthesia, sedation, and cerebral hemodynamic monitoring for patients undergoing interventional neuroradiologic procedures.

Anesthesia↗