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Biomedical subjects

M Taniuchi

Publications and source records attributed to M Taniuchi.

At least 19 recordsLinked to original sources

Randomized comparison of ticlopidine and clopidogrel after intracoronary stent implantation in a broad patient population.

BACKGROUND: Although clopidogrel is used to prevent subacute stent thrombosis, its safety and efficacy have not been compared with ticlopidine in a randomized manner in the United States. METHODS AND RESULTS: Patients with successful intracoronary stent implantation were randomly assigned to therapy with ticlopidine or clopidogrel. Loading doses were administered immediately after the procedure, and the drugs were prescribed for 2 weeks. One thousand sixteen patients were enrolled: 522 patients were randomly assigned to ticlopidine therapy and 494 to clopidogrel. High-risk characteristics included recent myocardial infarction in 41.4% of the cases, angiographically evident thrombus in 20.9%, and abrupt or threatened closure in 3.64%. An intravenous glycoprotein IIb/IIIa inhibitor was used in 48.2% of the cases, and thrombocytopenia occurred in 1.43% of these patients. Failure to complete 2 weeks of therapy occurred in 3.64% of the patients treated with ticlopidine and in 1.62% of the patients treated with clopidogrel (P=0.043). Within 30 days, thrombosis of the stent occurred in 1.92% of the patients in the ticlopidine group and in 2.02% of the clopidogrel group (P=0.901). A major adverse cardiac event occurred in 4.60% of patients receiving ticlopidine and in 3.85% of patients receiving clopidogrel (P=0.551). CONCLUSIONS: Clopidogrel is better tolerated than ticlopidine during a 2-week regimen after intracoronary stent implantation. Combining either thienopyridine with an intravenous platelet IIb/IIIa inhibitor appears to be safe. When applied to a broad spectrum of patients receiving stent implantation, clopidogrel confers similar protection as ticlopidine against subacute stent thrombosis and major adverse cardiac events.

Abciximab↗

Safety and efficacy of suture-mediated closure after percutaneous coronary interventions.

Percutaneous coronary interventions (PCI) performed with concomitant use of heparin and platelet inhibitors are safe procedures with reported vascular complication rates of approximately 6.1%. EPILOG investigators demonstrated that utilizing a low-dose heparin regimen with abciximab, along with early sheath removal, vascular access-related bleeding was significantly lower than that reported in EPIC. Recently, a suture-mediated closure (SMC) device has been reported to be safe, appears effective, and may improve patient comfort by allowing early ambulation. We conducted a retrospective analysis (January 1999 to March 2000) of complication frequencies among PCI patients who underwent SMC and those who had manual compression (non-SMC). Furthermore, we compared the overall rates of complications to patients who underwent PCI prior to the introduction of SMC (1995-1998). When comparing the current cohort to the historical cohort, there was a significant decrease in the number of retroperitoneal bleeds (0.3% vs. 0.9%; P = 0.003), hematomas (5% vs. 9%; P < 0.001), pseudoaneurysms (1.2% vs. 2.7%; P < 0.001), and need for vascular surgery (0.9% vs. 2.8%; P < 0.001). There was no difference in the number of arterio-venous fistulas and a slight increase in transfusion needs (12% vs. 10%; P = 0.03). Within the current cohort, there was no difference in the vascular complications between SMC and non-SMC PCI patients, although there were lower rates of pseudoaneurysms (0.5% vs. 1.8%; P = 0.02) and transfusion requirements (72/880 vs. 132/874; P < 0.001). These results suggest that the complication rates for SMC are not different and may be lower when compared to non-SMC patients after PCI. At our institution, the practice of early sheath removal and less aggressive heparin dosing has led to a decrease in vascular complication rates and a 66% reduction in vascular surgeries on post-PCI patients. Because of the limitations of retrospective analyses, further studies will be necessary to confirm these findings.

Aged↗

Myocardial bridging of the left anterior descending coronary artery in acute inferior wall myocardial infarction.

BACKGROUND: We observed marked myocardial bridging of the left anterior descending coronary artery (LAD) in the acute stages of inferior wall myocardial infarction (MI) in a group of patients who developed shock despite successful reperfusion of the infarct-related lesion (IRL). HYPOTHESIS: The purpose of this study was to elucidate the clinical significance of myocardial bridging in patients with inferior wall MI and shock. METHODS: The study group consisted of 53 patients with single-vessel disease of the right coronary artery, who underwent coronary angiography for acute inferior wall MI. Clinical characteristics, coronary angiographic findings, and left ventricular function during the chronic phase were compared between the patients who developed shock (the shock group) and those who did not (the non-shock group). In addition, a multiple logistic analysis was performed to identify independent predictors of shock in patients with acute inferior wall MI. RESULTS: Reperfusion of the IRL was obtained in all 53 patients. The incidence of myocardial bridging of the LAD, the incidence of right ventricular MI, the peak creatine phosphokinase (CPK-MB). the pulmonary capillary wedge pressure, and the prevalence of pulmonary congestion seen on chest roentgenogram were significantly higher in the shock group than in the non-shock group. Myocardial bridging (p = 0.0018), right ventricular MI (p = 0.0374), and peak CPK-MB (p = 0.0189) were identified as independent predictors of shock in acute inferior wall MI. CONCLUSION: This study suggests that myocardial bridging plays a role in left ventricular function in the acute stage of inferior wall MI.

Adult↗

ST-segment elevation in leads I and aVL predicts short-term prognosis in acute anterior wall myocardial infarction.

Our study demonstrates that ST-segment elevation in both leads I and aVL noted on admission for an anterior acute myocardial infarction does portend a worse short-term survival. Independent predictors of short-term prognosis in an anterior acute myocardial infarction include ST elevation in both leads I and aVL, advanced age, female gender, left ventricular failure, and malignant arrhythmias.

Adult↗

Severity of residual stenosis of infarct-related lesion and left ventricular function after single-vessel anterior wall myocardial infarction: implication of ST-segment elevation in lead aVL of the admission electrocardiograms.

BACKGROUND: The relationship between the severity of chronic-phase stenosis of infarct-related lesions (IRLs) and chronic left ventricular function in anterior acute myocardial infarctions (AMI) has not been adequately investigated. HYPOTHESIS: This study investigated whether ST elevation in lead aVL of admission electrocardiogram (ECG) would be a determinant factor of the relationship between the severity of stenosis of the IRL and chronic left ventricular function after anterior wall AMI. METHODS: One month after AMI, the IRL was evaluated by coronary angiography in 98 patients with anterior AMI, and left ventricular ejection fraction (LVEF) was determined using multigated radionuclide angiocardiography. Patients were classified according to the severity of the IRL: patients with 100% occlusion (Group O), patients with 90 to 99% stenosis (Group H), and patients with < or =75% stenosis (Group L). Patients with ST elevation > or =0.1 mV in the aVL lead on their admission ECG were included in the ST-elevation group, and those with ST elevation <0.1 mV were included in the non-ST-elevation group. RESULTS: The LVEF was greater in the non-ST-elevation group than in the ST-elevation group (p<0.0001), and the LVEF in a whole group as follows: Group L LVEF>Group H LVEF>Group O LVEF (p = 0.0160). In the ST-elevation group, LVEF was higher in Group L than in the other groups (p = 0.0251). There were three independent predictors of a reduced LVEF: ST-elevation in aVL [odds ratio (OR): 3.38, p = 0.0044], IRL stenosis > or =90% (OR: 2.90, p = 0.0044), and the IRL occurring in the left anterior descending artery proximal to the first diagonal branch (OR: 6.31, p = 0.0024). CONCLUSION: Left ventricular function was preserved, regardless of the severity of residual stenosis, in patients without ST elevation in aVL if the IRL was not totally occluded. In patients with ST elevation in aVL, LVEF was lower in patients with more severe stenosis, even if the IRL was patent.

Adult↗

Cardiac rupture and admission electrocardiography in acute anterior myocardial infarction: implication of ST elevation in aVL.

This study determines the usefulness of electrocardiography in the emergency room for assessing the risk of cardiac rupture after acute anterior myocardial infarction (MI). The presence of ST segment elevation on the admission 12-lead electrocardiography was evaluated in 325 consecutive anterior MI patients. A forward-stepwise logistic regression analysis for cardiac rupture was performed with the covariates of age, gender, hypertension, history of MI, reperfusion therapy by coronary angioplasty, and ST segment elevations in leads I, aVL, V1-V6. Cardiac rupture occurred in 16 patients, including 7 with left ventricular free wall rupture (FWR) and 9 with ventricular septal perforation (VSP). For FWR, ST elevation in lead aVL was the only independent predictor (odds ratio = 12.1, P = .0215). For VSP, female gender (odds ratio = 5.32, P = .0201) was the independent predictor. In conclusion, in patients with acute anterior MI, ST segment elevation in lead aVL on the admission electrocardiography is a significant risk factor for left ventricular FWR.

Adult↗

Lysophosphatidylcholine up-regulates IL-1 beta-induced iNOS expression in rat mesangial cells.

BACKGROUND: Nitric oxide (NO), a simple molecule synthesized from L-arginine by NO synthases (NOS), has been identified to play an important role in cell communication, cell defense and cell injury. Several studies have shown that glomeruli from rats with immune-mediated glomerular inflammation have increased production of NO. Recently, it was also reported that inducible NOS (iNOS) is localized in mesangial cells, glomerular epithelial cells and infiltrating cells in the diseased human glomeruli. On the other hand, while oxidized low density lipoprotein (ox-LDL) has been suggested to be related to progression of glomerular disease, the mechanism remains unknown. We investigated the effect of lysophosphatidylcholine (LPC), a modified phospholipid produced during LDL oxidation, on iNOS expression in rat mesangial cells. METHODS AND RESULTS: Treatment of mesangial cells with interleukin-1 beta (IL-1 beta) induced iNOS activity measured as nitrite levels in cell culture supernatants. Treatment with LPC had no effect. In contrast, coincubation with LPC and IL-1 beta resulted in a markedly higher nitrite content compared to that after incubation with IL-1 beta alone. Western blot analysis revealed that LPC caused a significant increase in the formation of iNOS protein in the presence of IL-1 beta. CONCLUSION: These findings suggest that LPC may contribute to progression of glomerular inflammation by augmenting IL-1 beta-induced iNOS expression.

Animals↗

High-resolution magnetic resonance coronary angiography of the entire heart using a new blood-pool agent, NC100150 injection: comparison with invasive x-ray angiography in pigs.

Recent developments of novel magnetic resonance intravascular contrast agents with low T1 in blood and a long intravascular half-life will rapidly position magnetic resonance coronary angiography (MRCA) at the threshold of clinical application. This article describes the use of one such intravascular contrast agent for noninvasive coronary angiography and comparison with routine invasive x-ray angiography. Six domestic farm pigs with an artificial stenoses at the left circumflex were studied. NC100150 Injection, a new ultra-small superparmagnetic iron oxide (Nycomed Amersham Imaging, Oslo, Norway), was injected using a dose of 5.0 mg Fe/kg body weight. Scanning was done using a 1.5-T Gyroscan ACS-NT. A high-resolution electrocardiogram-triggered scan covering the entire heart was applied. Navigator echoes were used for respiratory triggering. In all animals the location of the stenoses detected with MRCA correlated well with x-ray angiography. The correlation factor between the grade of stenoses determined by MRCA and x-ray angiography was 0.993. MRCA using NC100150 Injection can depict the major coronary arteries and branches well. Decreases in vessel caliber detected by MRCA correlate well with x-ray angiography. The use of such intravascular contrast agents show great promise for clinical applications for noninvasive detection of coronary artery disease in humans.

Animals↗

Asynergy of the noninfarcted left ventricular inferior wall in anterior wall acute myocardial infarction secondary to isolated occlusion of the left anterior descending artery.

There are patients in whom left ventricular (LV) wall motion decreases in the noninfarcted region and LV systolic function declines globally despite the presence of a localized myocardial infarct attributable to narrowing or occlusion of a single coronary artery. This study examines angiographic characteristics of patients with chronic hypokinesia of noninfarcted myocardium after anterior wall acute myocardial infarction (AMI) due to narrowing of a single coronary artery, namely, the left anterior descending (LAD) artery. The LV ejection fraction, abnormalities in the motion of the noninfarcted LV inferior wall (SD/chord value by Sheehan's technique), the angiographic characteristics of the infarct-related coronary artery, the effect of acute reperfusion therapy, and presence of coronary risk factors were examined in 85 consecutive patients. The SD/chord value in the noninfarcted region showed a positive correlation with the LV ejection fraction (r = 0.505, p <0.0001). By multivariate analysis, hypertension (odds ratio = 0.53, 95% confidence interval [CI] 0.36 to 0.80), an infarct-related narrowing proximal to the origin of the first diagonal branch (odds ratio = 0.56, 95% CI 0.38 to 0.84), and patency of the infarct-related lesion during AMI (odds ratio = 1.56, 95% CI 1.03 to 2.30) were independent predictors of wall motion in the noninfarct region. In some patients with single-vessel anterior wall AMI, the motion of the noninfarcted inferior LV wall decreases during the chronic stage and cardiac function declines severely. In most of these patients, the infarct-related narrowing or occlusion is proximal to the origin of the first diagonal branch of the LAD artery.

Aged↗

Nicotinic receptor mediates nitric oxide synthase expression in the rat gastric myenteric plexus.

The mechanism that regulates the synthesis of nitric oxide synthase (NOS), a key enzyme responsible for NO production in the myenteric plexus, remains unknown. We investigated the roles of the vagal nerve and nicotinic synapses in the mediation of NOS synthesis in the gastric myenteric plexus in rats. Truncal vagotomy and administration of hexamethonium significantly reduced nonadrenergic, noncholinergic relaxation, the catalytic activity of NOS, the number of NOS-immunoreactive cells, and the density of NOS-immunoreactive bands and NOS mRNA bands obtained from gastric tissue. These results suggest that NOS expression in the gastric myenteric plexus is controlled by the vagal nerve and nicotinic synapses. We also investigated if stimulation of the nicotinic receptor increases neuronal NOS (nNOS) expression in cultured gastric myenteric ganglia. Incubation of cultured gastric myenteric ganglia with the nicotinic receptor agonist, 1,1-dimethyl-4-phenylpiperizinium (DMPP, 10(-10)-10(-7) M), for 24 h significantly increased the number of nNOS-immunoreactive cells and the density of immunoreactive nNOS bands and nNOS mRNA bands. nNOS mRNA expression stimulated by DMPP was antagonized by a protein kinase C antagonist, a phospholipase C inhibitor, and an intracellular Ca2+ chelator. We concluded that activation of the nicotinic receptor stimulates a Ca2+-dependent protein kinase C pathway, which in turn, upregulates nNOS mRNA expression and nNOS synthesis in the gastric myenteric plexus.

Animals↗

ST-segment elevation in right precordial leads implies depressed right ventricular function after acute inferior myocardial infarction.

BACKGROUND: The prognosis of acute inferior myocardial infarction is worse when it is complicated by right ventricular infarction. ST elevation in the right precordial leads is one of the reliable methods for detecting acute right ventricular infarction. The purpose of the study was to examine the relation between ST elevation in the right precordial electrocardiographic leads during acute inferior infarction and the severity of right ventricular systolic dysfunction. METHODS: This study analyzed the relation between ST elevation > or = 0.1 mV in V4R and the severity of right ventricular systolic dysfunction in 43 consecutive patients (men/women: 35/8; average age 62+/-9 years) with acute inferior myocardial infarction with a rapid-response Swan-Ganz catheter to measure the right ventricular ejection fraction (RVEF). RESULTS: RVEF was significantly lower in patients with ST elevation (n = 18) than in those without (n = 25) (33%+/-6% vs 40%+/-9%, p = 0.010). If the infarct-related lesion was located in the proximal right coronary artery, RVEF tended to be lower than if the lesion was located in the distal right coronary artery or the left circumflex coronary artery (33%+/-10% vs 37%+/-9% vs 42%+/-9%, p = 0.101). Logistic regression analysis demonstrated that ST elevation in V4R was the only independent predictor of depressed RVEF (odds ratio = 5.31, 95% confidence interval = 1.28 to 22.1, p = 0.022). CONCLUSION: ST elevation in lead V4R during acute inferior myocardial infarction predicts right ventricular systolic dysfunction.

Adult↗

Clinical significance of hypoxemia without congestive heart failure in patients presenting with acute myocardial infarction.

This study investigated the clinical significance of hypoxemia without apparent clinical congestive heart failure in patients with acute myocardial infarction (AMI). Sixty-two patients with AMI of the Killip group I and Forrester subset I state were stratified into a hypoxemia group and a normoxemia group. The increase in the neutrophil count and the severity of the coronary artery disease as graded by Gensini's score were significantly higher in the hypoxemic group. The cardiac index was lower in hypoxemic than normoxemic patients. Myocardial scintigraphy revealed no acute difference in defect scores (DS) or left ventricular ejection fraction (LVEF) between the two groups, but DS was significantly higher (p < 0.01) and LVEF was lower (p < 0.01) in the hypoxemic group 2 years after infarction. Patients with hypoxemia have a more severe angiographic coronary pathology than normoxemic patients, and latent cardiac hypofunction occurs.

Adult↗

Directed proximal magnetic resonance coronary angiography compared with conventional contrast coronary angiography.

Magnetic resonance coronary angiography in 36 patients with proximal 1-vessel disease within 1 week of contrast coronary angiography was performed and the time required to complete the study was 13.4 +/- 4.2 min 13.2 +/- 8.1 minutes for the right and left coronary arteries, respectively. The sensitivity, specificity, positive and negative predictive values, and accuracy of magnetic resonance coronary angiography were 100% for right cronary artery disease, and 83%, 98%, 94%, 94%, and 94%, respectively, for left coronary artery disease.

Aged↗

Co-culture of embryonic chick heart cells and ciliary ganglia induces parasympathetic responsiveness in embryonic chick heart cells.

We have developed a system for the co-culture of embryonic chick heart cells obtained from embryos at 3.5 days in ovo with ciliary ganglia from chick embryos at 7 days in vivo. After 3 days of co-culture, removal of the ciliary ganglia resulted in complete degeneration of axons within 6-8 h, leaving the post-innervated heart cell culture devoid of neurons. Embryonic chick heart cells at 3.5 days in ovo are unresponsive to muscarinic stimulation. However, following 3 days of co-culture with ciliary ganglia, the heart cells developed a negative chronotropic response to muscarinic stimulation (paired t test, P < 0.02) which persisted for at least 24 h after removal of the ciliary ganglion. The development of muscarinic responsiveness was associated with an increase in the levels of specific alpha-subunits of the guanine nucleotide binding proteins (G-proteins), with a 3-fold increase in the level of alpha 39 (39 kDa subunit) and a 2.5-fold increase in the level of alpha 41. The level of the G-protein subunit alpha s remained unchanged. Culture of embryonic chick heart cells at 3.5 days in ovo with medium conditioned by the growth of embryonic chick heart cells and ciliary ganglia had an effect on the chronotropic response to muscarinic stimulation and on alpha 39 and alpha 41 levels identical to that of co-culture. These data suggest that a soluble factor released during the co-culture of embryonic chick heart cells and ciliary ganglia is capable of inducing muscarinic responsiveness. These studies suggest that innervation of the heart may induce parasympathetic responsiveness by increasing the availability of G-proteins which couple the muscarinic receptor to a physiological response.

Animals↗

Destruction of sympathetic and sensory neurons in the developing rat by a monoclonal antibody against the nerve growth factor (NGF) receptor.

The ability of the monoclonal antibody, 192-IgG, directed against the rat nerve growth factor (NGF) receptor to mimic or inhibit the actions of NGF was examined in vitro and in vivo. 192-IgG had no effect on morphology, survival, or protein synthesis rates of sympathetic neuronal cultures. When injected into newborn rats, destruction of sympathetic, but not sensory, neurons was produced. Injection prenatally produced more dramatic destruction of sympathetic neurons and, in addition, destruction of neural crest-derived sensory neurons. Therefore, although 192-IgG had no discernible effects in vitro, it produced a pattern of neuronal destruction in vivo qualitatively similar to that produced by antibodies to NGF itself.

Adrenergic Fibers↗

Expression of nerve growth factor receptors by Schwann cells of axotomized peripheral nerves: ultrastructural location, suppression by axonal contact, and binding properties.

Axotomy of sciatic nerve fibers in adult rats induces expression of NGF receptor in the entire population of Schwann cells located distal to the injury (Taniuchi et al., 1986b). In the present study we have used immunocytochemistry, with a monoclonal antibody directed against the rat NGF receptor, to examine axotomized peripheral nerves by light and electron microscopy. We have found that (1) the NGF receptor molecules were localized to the cell surface of Schwann cells forming bands of Bungner; (2) axonal regeneration into the distal portion of sciatic nerve coincided temporally and spatially with a decrease in Schwann cell expression of NGF receptor; (3) Schwann cell NGF receptor could be induced by axotomy of NGF-independent neurons, such as motoneurons and parasympathetic neurons; and (4) the presence of axon-Schwann cell contact was inversely related to expression of Schwann cell NGF receptor. Using biochemical assays we have found that, in striking contrast to peripheral nerves, there was no detectable induction of NGF receptor in the spinal cord and brain after axotomy of NGF receptor-bearing fibers. Filtration assays of 125I-NGF binding to the induced NGF receptors of Schwann cells measured a Kd of 1.5 nM and a fast dissociation rate, both characteristics of class II receptor sites. We conclude that Wallerian degeneration induces Schwann cells, but not central neuroglia, to produce and position upon their plasmalemmal surface the class II NGF receptor molecules. The induction is ubiquitous among Schwann cells, irrespective of the type of axon they originally ensheathed. Expression of Schwann cell NGF receptor is negatively regulated by axonal contact, being induced when axons degenerate and suppressed when regenerating axons grow out along the Schwann cell surface. We propose that the induced NGF receptors function to bind NGF molecules upon the Schwann cell surface and thereby provide a substratum laden with trophic support and chemotactic guidance for regenerating sensory and sympathetic neurons.

Animals↗