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Biomedical subjects

Kazuyuki Shimada

Publications and source records attributed to Kazuyuki Shimada.

At least 109 records · Page 6Linked to original sources
PubMed2002

Therapeutic angiogenesis for patients with limb ischaemia by autologous transplantation of bone-marrow cells: a pilot study and a randomised controlled trial.

BACKGROUND: Preclinical studies have established that implantation of bone marrow-mononuclear cells, including endothelial progenitor cells, into ischaemic limbs increases collateral vessel formation. We investigated efficacy and safety of autologous implantation of bone marrow-mononuclear cells in patients with ischaemic limbs because of peripheral arterial disease. METHODS: We first did a pilot study, in which 25 patients (group A) with unilateral ischaemia of the leg were injected with bone marrow-mononuclear cells into the gastrocnemius of the ischaemic limb and with saline into the less ischaemic limb. We then recruited 22 patients (group B) with bilateral leg ischaemia, who were randomly injected with bone marrow-mononuclear cells in one leg and peripheral blood-mononuclear cells in the other as a control. Primary outcomes were safety and feasibility of treatment, based on ankle-brachial index (ABI) and rest pain, and analysis was per protocol. FINDINGS: Two patients were excluded from group B after randomisation. At 4 weeks in group B patients, ABI was significantly improved in legs injected with bone marrow-mononuclear cells compared with those injected with peripheral blood-mononuclear cells (difference 0.09 [95% CI 0.06-0.11]; p<0.0001). Similar improvements were seen for transcutaneous oxygen pressure (13 [9-17]; p<0.0001), rest pain (-0.85 [-1.6 to -0.12]; p=0.025), and pain-free walking time (1.2 [0.7-1.7]; p=0.0001). These improvements were sustained at 24 weeks. Similar improvements were seen in group A patients. Two patients in group A died after myocardial infarction unrelated to treatment. INTERPRETATION: Autologous implantation of bone marrow-mononuclear cells could be safe and effective for achievement of therapeutic angiogenesis, because of the natural ability of marrow cells to supply endothelial progenitor cells and to secrete various angiogenic factors or cytokines.

Aged↗
PubMed2002

U-curve relationship between orthostatic blood pressure change and silent cerebrovascular disease in elderly hypertensives: orthostatic hypertension as a new cardiovascular risk factor.

OBJECTIVES: The study investigated the clinical significance and mechanism of orthostatic blood pressure (BP) dysregulation in elderly hypertensive patients. BACKGROUND: Although orthostatic hypotension (OHYPO), often found in elderly hypertensive patients, has been recognized as a risk factor for syncope and cardiovascular disease, both the clinical significance and the mechanism of orthostatic hypertension (OHT) remain unclear. METHODS: We performed a head-up tilting test and brain magnetic resonance imaging (MRI) in 241 elderly subjects with sustained hypertension as indicated by ambulatory BP monitoring. We classified the patients into an OHT group with orthostatic increase of systolic blood pressure (SBP) of >or=20 mm Hg (n = 26), an OHYPO group with orthostatic SBP decrease of >or=20 mm Hg (n = 23), and a normal group with neither of these two patterns (n = 192). RESULTS: Silent cerebral infarcts were more common in the OHT (3.4/person, p < 0.0001) and OHYPO groups (2.7/person, p = 0.04) than in the normal group (1.4/person). Morning SBP was higher in the OHT group than in the normal group (159 vs. 149 mm Hg, p = 0.007), while there were no significant differences of these ambulatory BPs between the two groups during other periods. The OHT (21 mm Hg, p < 0.0001) and OHYPO (20 mm Hg, p = 0.01) groups had higher BP variability (standard deviation of awake SBP) than the normal group (17 mm Hg). The associations between orthostatic BP change and silent cerebrovascular disease remained significant after controlling for confounders, including ambulatory BP. The orthostatic BP increase was selectively abolished by alpha-adrenergic blocking, indicating that alpha-adrenergic activity is the predominant pathophysiologic mechanism of OHT. CONCLUSIONS: Silent cerebrovascular disease is advanced in elderly hypertensives having OHT. Elderly hypertensives with OHT or OHYPO may have an elevated risk of developing hypertensive cerebrovascular disease.

Adrenergic alpha-Antagonists↗
PubMed2002

Monocyte chemoattractant protein-1 and coronary artery disease.

The designation of atherosclerosis as a chronic inflammatory process represents an exciting and logical paradigm shift for cardiologists. Monocyte chemoattractant protein-1 (MCP-1) plays an important role in the recruitment and activation of monocytes and thus in the development of atherosclerosis. Enhanced MCP-1 expression has been detected in macrophages, endothelial cells, and vascular smooth muscle cells in the atheromatous plaque. Activation of macrophages by MCP-1 also appears to be involved in the vulnerability of the plaque. Indeed, circulating MCP-1 levels are elevated in patients with acute myocardial infarction and in those with unstable angina, but not in patients with stable angina. Production of MCP-1 and macrophage accumulation are also observed after coronary angioplasty or grafting, indicating that MCP-1 expression may be related not only to instability of atheromatous plaques, but also to the formation of restenotic lesions. The development of therapeutic drugs for atherosclerosis targeted specially against MCP-1 may be useful in the prevention of plaque formation and future myocardial infarction.

Angina, Unstable↗
PubMed2002

AAV-mediated VEGF gene transfer into skeletal muscle stimulates angiogenesis and improves blood flow in a rat hindlimb ischemia model.

OBJECTIVES: Clinical trials on therapeutic angiogenesis using vascular endothelial growth factor (VEGF) are ongoing, however the benefits of these therapies are still controversial. To establish a more efficient gene transfer method for ischemic diseases, we investigated the therapeutic potential of adeno-associated virus (AAV)-mediated VEGF gene transfer. METHODS: We produced VEGF(165)-expressing AAV vectors (AAV-VEGF). HEK-293 cells were transduced with AAV-VEGF in vitro and VEGF expression and secretion were examined. We used a rat ischemic hindlimb model and AAV-VEGF was administered intramuscularly into the ischemic limb. Gene expression was evaluated by RT-PCR and ELISA. Six weeks after gene transfer, we measured the blood flow of limb vessels and the skin temperature of limbs. Histochemical examination was performed to illustrate capillary growth. RESULTS: Western blotting and ELISA revealed VEGF protein expression and secretion from AAV-VEGF-transduced HEK-293 cells. VEGF mRNA and protein expression was consistently observed in the injected muscle at least 10 weeks after the injection, while no VEGF mRNA could be detected at remote organs. The mean blood flow in AAV-VEGF-transduced ischemic limbs was significantly higher than in AAV-LacZ-transduced limbs. Capillary density was significantly higher in AAV-VEGF-injected tissues than in AAV-LacZ-injected tissues. CONCLUSIONS: This study demonstrates that (1) AAV-mediated VEGF gene transfer into rat skeletal muscles is efficient and stable without ectopic expression, and (2) AAV-mediated VEGF gene transfer stimulates angiogenesis and thereby improves blood flow in a rat hindlimb ischemia model. These findings suggest that AAV-mediated VEGF gene transfer may be useful for treatment of ischemic diseases.

Adenoviridae↗
PubMed2002

C-Reactive protein augments inducible nitric oxide synthase expression in cytokine-stimulated cardiac myocytes.

OBJECTIVE: Nitric oxide (NO) production by inducible NO synthase (iNOS) can exert negative inotropic and cytotoxic effects on cardiac myocytes and may play an important role in the pathogenesis of cardiac dysfunction and remodeling. An elevated serum level of C-reactive protein (CRP) is an important predictive factor for cardiac disorders including acute myocardial infarction and dilated cardiomyopathy. The basic mechanisms responsible for this association are not clear; CRP may merely be a marker of inflammation with no specific role in the pathogenesis of cardiac disease or may directly modulate the disease process. We investigated the effects of CRP on iNOS expression and subsequent NO synthesis in rat cardiac myocytes, and the mechanism by which CRP exerts its effects. METHODS: NO production by culture neonatal rat cardiac myocytes was determined by measurement of nitrite contents in the culture medium. The expression of iNOS mRNA and protein were measured by reverse transcription-polymerase chain reaction and Western blotting, respectively. The levels of nuclear factor (NF)-kappaB proteins were analyzed by a gel retardation assay. RESULTS: Incubation of cardiac myocytes with interleukin-1beta (IL-1beta; 10 ng/ml) caused a significant increase in nitrite production. CRP significantly increased the IL-1beta-induced nitrite production in a dose-dependent manner (10-100 microg/ml). Incubation with IL-1beta induced the expression of iNOS mRNA and protein in cardiac myocytes, and CRP enhanced their expression. Addition of IL-1beta activated NF-kappaB in cardiac myocytes, while CRP did not affect IL-1beta-induced NF-kappaB activation. CONCLUSIONS: These results indicated that CRP directly enhances NO synthesis in IL-1beta-stimulated cardiac myocytes through an NF-kappaB-independent mechanism.

Animals↗
PubMed2002

Diagnostic implications of circulating oxidized low density lipoprotein levels as a biochemical risk marker of coronary artery disease.

OBJECTIVES: To examine the diagnostic performance of circulating oxidized low density lipoprotein levels as a biochemical risk marker of coronary heart disease. DESIGN AND METHODS: 361 patients with coronary artery disease and 710 healthy volunteers as normal controls were examined. Receiver-operating characteristics curve analysis in addition to statistical analysis (univariate, multivariate) were done to determine the usefulness of the assay. RESULTS: Patients with coronary artery disease showed significantly elevated circulating oxidized low density lipoprotein levels. Males less than 70 years of age showed a significant association between oxidized low density lipoprotein levels and coronary artery disease. Receiver-operating characteristics curve analysis showed superior performance (e.g., sensitivity, specificity) of oxidized low density lipoprotein as a diagnostic marker of coronary artery disease as compared against other lipid markers (total cholesterol, triglyceride, high density lipoprotein, lipoprotein (a), and total cholesterol to high density lipoprotein ratio) with optimal performance in younger males. CONCLUSIONS: Oxidized low density lipoprotein levels may be a promising biochemical risk marker of atherosclerotic disease, especially in young males.

Adult↗
PubMed2002

Matrix metalloproteinase expression in the coronary circulation induced by coronary angioplasty.

Recent studies have revealed that matrix metalloproteinases (MMPs) play an important role in cardiovascular remodeling by degrading the extracellular matrix. We investigated changes in the expression of MMPs due to percutaneous transluminal coronary angioplasty (PTCA). We studied 47 patients with ischemic heart disease who underwent elective PTCA on isolated stenotic lesion of left coronary arteries. Twelve patients received conventional balloon angioplasty, 14 percutaneous transluminal rotational atherectomy and 21 stent implantation. Blood samples were drawn from the coronary sinus immediately before and after, as well as 4 and 24 h, after PTCA. Plasma levels of MMP-1, MMP-2, tissue inhibitor of MMP (TIMP)-1 and TIMP-2 were measured by enzyme-linked immunosorbent assay. Plasma MMP-2 activity was determined with the digestion of a specific chromogenic peptide substrate. We could observe serial changes in plasma MMP-1 levels in the coronary circulation only in one patient, because MMP-1 levels were lower than the limit of detection in other patients. On the other hand, plasma MMP-2 levels in the coronary sinus were detectable in all subjects and increased significantly 4 and 24 h after PTCA. Plasma TIMP-1 levels also showed significant increases 4 and 24 h after PTCA, whereas TIMP-2 did not show significant changes. Plasma MMP-2/TIMP-2 ratio and MMP-2 activity in the coronary sinus showed significant increases 4 and 24 h after PTCA. A positive correlation was observed between MMP-2 levels in the coronary sinus 4 h after PTCA and late loss index 6 months after PTCA. MMP-2 levels in the coronary sinus blood were significantly higher in patients with late restenosis than in those without restenosis. PTCA induces increases in plasma MMP-2 levels and activity in the coronary circulation, which may contribute to vascular remodeling and late restenosis after PTCA.

Adult↗
PubMed2002

Increased levels of monocyte-related cytokines in patients with unstable angina.

Inflammatory cytokines play important roles in coronary artery disease. We investigated the clinical significance of monocyte-related cytokine expression in patients with angina pectoris. We studied 26 patients with stable effort angina and 20 patients with unstable angina in whom stenotic lesions of the coronary arteries were confirmed by selective coronary angiography. Plasma levels of interleukin-6 (IL-6), macrophage colony stimulating factor (MCSF), and monocyte chemoattractant protein-1 (MCP-1) were measured. Plasma levels of IL-6, MCSF, and MCP-1 in patients with unstable angina were significantly higher than those in patients with stable angina or control subjects. Patients with unstable angina were further divided into sub-groups according to their clinical classification; Levels of IL-6, MCSF, and MCP-1 in patients, who had anginal attacks at rest within the 48 h prior to admission (Braunwald class IIIB) were significantly higher than those in patients, who did not have attacks at rest (class IB). Five unstable patients, who were refractory to medical therapy and were referred for emergency coronary revascularization showed marked elevation of plasma MCSF and MCP-1 levels. In conclusion, plasma levels of monocyte-related cytokines were elevated in unstable angina. These increases were marked in patients with unstable angina with recent ischemic attack at rest, suggesting that activation of monocytes is involved in vulnerability of underlying atheromatous plaque.

Adult↗
PubMed2002

Lysophosphatidylcholine induces apoptosis in human endothelial cells through a p38-mitogen-activated protein kinase-dependent mechanism.

Lysophosphatidylcholine (lysoPC) is a component of oxidized low density lipoprotein (LDL) and is involved in the pathogenesis of atherosclerosis and inflammation. Previous studies demonstrated that lysoPC can induce various protein kinases including tyrosine kinases, protein kinase C (PKC), and mitogen-activated protein kinases (MAPK) in vascular endothelial cells. However, the role of lysoPC-activated kinases remains undefined. In this study, we examined the effect of lysoPC on apoptosis and investigated the role of lysoPC-activated protein kinases in human umbilical vein endothelial cells (HUVEC). The presence of apoptosis was evaluated by morphological criteria, MTT assay, and electrophoresis of DNA fragments showing the characteristic apoptotic ladder, TUNEL analysis, and quantified as the proportion of hypodiploid cells by flow cytometry. The lysoPC induced apoptosis in a time- and dose-dependent manner. It stimulated the phosphorylation of extracellular signal-regulated kinase1/2 (ERK1/2) and p38-MAPK in HUVEC. The use of specific pharmacologic inhibitors indicated that the p38-MAPK-signaling pathway (SB203580) is required for lysoPC-induced apoptotic signals. Furthermore, lysoPC-induced apoptosis was inhibited by DEVD-FMK (a caspas-3/CPP32 inhibitor), suggesting involvement of an important segment in the apoptosis. These results demonstrate that lysoPC induces apoptosis in human endothelial cells through a p38-MAPK-dependent pathway.

Analysis of Variance↗
PubMed2002

beta-very low density lipoprotein enhances inducible nitric oxide synthase expression in cytokine-stimulated vascular smooth muscle cells.

beta-very low-density lipoprotein (beta-VLDL), a collective term for VLDL and chylomicron remnants, has recently shown to potently promote the development of atherosclerosis. However, the effects of beta-VLDL on the accumulation of nitric oxide (NO) and the expression of inducible NO synthase (iNOS) in vascular smooth muscle cells (VSMC) have not been determined. In this study, we measured the accumulation of nitrite, stable metabolite of NO and examined the expression of iNOS protein and mRNA using Western blotting and RT-PCR, respectively, in VSMC. NF-kappaB activation in VSMC was examined by gel retardation assay. Incubation of cell cultures with interleukin-1beta (IL-1beta) for 24 h caused a significant increase in nitrite accumulation. Although beta-VLDL alone did not increase nitrite accumulation in unstimulated VSMC, beta-VLDL significantly enhanced nitrite accumulation in IL-1beta-stimulated VSMC in a time- and dose-dependent manner. beta-VLDL-induced nitrite accumulation in IL-1beta-stimulated VSMC was accompanied by an increase in iNOS protein and mRNA expression. In addition, IL-1beta induced NF-kappaB activation in VSMC, an effect that was increased by the addition of beta-VLDL. Use of specific tyrosine kinase inhibitor herbimycin A, genistein, or PP2 (Src family kinase inhibitor) indicated that tyrosine kinases are required for IL-1beta-stimulated and beta-VLDL-enhanced nitrite accumulation, while specific inhibition of ERK1/2 or p38-MAP kinase had no effects. Our results suggest that beta-VLDL enhances iNOS expression and nitrite accumulation in IL-1beta-stimulated VSMC through tyrosine kinase(s)-dependent mechanisms.

Animals↗
PubMed2002

Regulation of interleukin-8 expression by HMG-CoA reductase inhibitors in human vascular smooth muscle cells.

Interleukin-8 (IL-8) is a potent chemotactic factor that has been implicated in atherogenesis. HMG-CoA reductase inhibitors (statins) may reduce the cardiovascular risk and vulnerability of atherosclerotic plaque through nonlipid mechanisms such as inhibition of cytokine expression. In this study, we investigated the effects of statins on IL-8 synthesis in human vascular smooth muscle cells (VSMCs). Addition of angiotensin II (Ang II) increased IL-8 production in VSMCs in a time (0-24 h)- and dose (10(-8)-10(-6) mol/l)-dependent manner with increased IL-8 mRNA accumulation. The Ang II type 1 receptor (AT1R) antagonist candesartan, but not the Ang II type 2 receptor (AT2R) antagonist PD123319, significantly blocked Ang II-induced IL-8 production. Addition of fluvastatin decreased the basal and Ang II-induced IL-8 production in VSMCs in a dose (10(-8)-10(-5) mol/l)-dependent manner with a decrease in IL-8 mRNA accumulation. The effect of fluvastatin on IL-8 production was completely reversed in the presence of mevalonate or geranylgeranyl-pyrophosphate, but not in the presence of squalene or farnesyl-pyrophosphate. Lipophilic cerivastatin also significantly decreased IL-8 production, while hydrophilic pravastatin showed no effect on IL-8 levels. In conclusion, we demonstrated for the first time that Ang II increased IL-8 production and fluvastatin decreased the basal and Ang II-induced IL-8 production in human VSMCs. These findings suggested that Ang II may exacerbate atherosclerosis through induction of IL-8 in VSMCs, while statins may exert therapeutic effects by modulating IL-8 synthesis in patients with atherosclerotic disease.

Analysis of Variance↗
PubMed2002

Neurohumoral characteristics of older hypertensive patients with abnormal nocturnal blood pressure dipping.

Abnormal patterns of diurnal blood pressure (BP) variation have been reported to be related to advanced target organ damage and poor cardiovascular prognosis. However, the neurohumoral characteristics of patients with such variation have not been fully investigated. We measured BP and plasma levels of neurohumoral factors (norepinephrine [NE], epinephrine, renin, and arginine vasopressin [VP]) during the 70 degree head-up tilt test (10 min supine and 15 min tilting) in 120 older subjects (mean age 71 years) who had sustained hypertension as determined by ambulatory BP monitoring. They who were subclassified according to the nocturnal systolic BP fall as follows: 28 extreme dippers with >20% nocturnal BP fall; 78 dippers with >0% but <20% fall; and 14 nondippers with <0% fall. Plasma renin activity (r = 0.22, P = .02) and VP level (r = 0.36, P < .0001) after tilting were positively associated with the nocturnal systolic BP fall. Plasma NE levels were significantly higher in nondippers than in dippers in both the supine and tilting positions (supine 519 v 315 pg/mL, P = .001; tilting 803 v 550 ng/mL, P < .01), whereas the increase of NE induced by tilting was comparable in the two groups. Plasma renin activity in both the supine and tilting positions was comparable in the three groups, but the increase of this activity caused by tilting was less marked in the nondippers than in the extreme dippers (0.05 v 0.26 ng/mL/min, P = .02) and dippers (0.21 ng/mL/min, P = .07). Plasma VP was markedly increased after tilting in the extreme dippers compared with dippers (3.8 v 2.6 pg/mL, P < .001) and nondippers (v 2.0 pg/mL, P < .001), whereas the levels in the supine position were comparable in the three groups (2.0 pg/mL for extreme dippers, 1.9 pg/mL for dippers, 1.6 pg/mL for nondippers). In conclusion, diurnal BP variation in elderly hypertensive individuals was significantly associated with neurohumoral factors regulating circulating blood volume. Increased VP after tilting in extreme dippers might counteract reduced circulating blood volume, whereas nondippers appear to have alpha- and beta-adrenergic subsensitivity that may be induced by their chronic exposure to high NE levels.

Age Factors↗
PubMed2002

Incomplete benefit of antihypertensive therapy on stroke reduction in older hypertensives with abnormal nocturnal blood pressure dipping (extreme-dippers and reverse-dippers).

To determine whether the benefits of antihypertensive treatment vary according to dipper status, 811 asymptomatic elderly Japanese hypertensives underwent 24-h ambulatory blood pressure monitoring. During a mean follow-up period of 41 months, 32 stroke events were observed in patients who remained nonmedicated (n = 385), and in 27 patients in the medicated group (n = 426), indicating a 24% lower rate of stroke as a result of antihypertensive therapy. Patients were divided into a white-coat hypertensive (WCHT) group (ambulatory blood pressure <130/80 mm Hg; n = 236) and a sustained hypertensive (SHT) group (n = 575). Sixty-one percent of SHT and 32% of WCHT patients were being medicated. In the SHT group, the stroke rates were 12.4% in nonmedicated and 7.4% in medicated group (P =.04), whereas in the WCHT group the stroke rates were 2.5% in nonmedicated and 1.3% in medicated group (P = not significant). The SHT were further classified according to their nocturnal systolic blood pressure (BP) decrease, as follows: 97 extreme-dippers with >20% nocturnal systolic BP decrease; 230 dippers with >10% but <20% decrease; 185 nondippers with >0% but <10% decrease; 63 reverse-dippers with <0% decrease. In the dipping groups of SHT, the stroke rates were similar according to medication versus no-medication in extreme-dippers (12% v 13%), and reverse-dippers (23% v 22%), but in nondippers there was a significantly lower rate (by 65%, P =.038) in the medicated (4.4%) than the nonmedicated (13%) groups. In dippers, the stroke rate was also lower in the medicated than the nonmedicated patients (4.7% v 8.8%), a decrease of 47% (P =.217), although the difference was not significant. In conclusion, in older SHT subjects, antihypertensive therapy using clinic BP may be less effective for the groups with extremely abnormal diurnal BP patterns (extreme-dippers and reverse-dippers) than those with relatively normal patterns (dippers and nondippers). Patients with WCHT also showed no benefit.

Aged↗
PubMed2002

Morphological study of the human chondroglossus muscle in Japanese.

The chondroglossus muscle was macroscopically studied to clarify its fundamental morphology. This muscle was present in all of the 100 tongue halves examined in Japanese cadavers. In 14% of the specimens, however, the muscular fibers were sparse and vestigial. Originating mainly from the medial side of the lesser cornu of the hyoid bone, the chondroglossus muscle passed upward to penetrate the inferior longitudinal muscle of the tongue, and immediately entered the genioglossus muscle. Ascending inside the genioglossus muscle, it's bundles spread, taking a broom head or a fan-like shape. Thereafter it reached the submucosal layer in the root of the tongue, changed the direction from upward to forward, and terminated diffusely, never going past the sulcus terminalis. The origin, course, and spreading manner of the chondroglossus muscle were quite different from those of the hyoglossus muscle. The nerve fiber supplying the chondroglossus muscle was a ramus from the first lateral branch of the hypoglossal nerve. It should be considered a separate extrinsic lingual muscle independent of the hyoglossus muscle, although they have a phylogenetically close relationship.

Adolescent↗