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Biomedical subjects

R Murakami

Publications and source records attributed to R Murakami.

At least 55 records · Page 3Linked to original sources
PubMed1999

Three new bicyclic taxane diterpenoids from the needles of Japanese yew, Taxus cuspidata Sieb. et Zucc.

Three new bicyclic taxane diterpenes were isolated from the needles of the Japanese yew, Taxus cuspidata Sieb. et Zucc. Their structures were established to be 7,9,10,13-tetraacetoxy-5-cinnamoyloxy-4-hydroxy-methyl-8,12,15,15- tetramethyl-bicyclo[9.3.1] pentadeca-3,8,11-trien-2-ol (2,20-dideacetyl taxuspine X), 7,9,10,13,20-pentaacetoxy-5-cinnamoyloxy-8,12,15,15-tetramethyl bicyclo[9.3.1] pentadeca-3,8,11-trien-2-ol (2-deacetyl taxuspine X), and 9,10,13,20-tetraacetoxy-5-cinnamoyloxy-8,12,15,15-tetramethyl-bicyclo[9.3.1] pentadeca-3,8,11-trien-2,7-diol (2,7-dideacetyl taxuspine X) with the aid of spectroscopic techniques and by comparing with taxuspine X.

Diterpenes↗
PubMed1999

Two new taxane diterpenoids from the seeds of the Chinese yew, Taxus yunnanensis.

A new taxoid and a taxinine analogue were isolated from the seeds of the Chinese yew, Taxus yunnanensis. The structures were established as 13 alpha-acetoxy-5 alpha-(3'-dimethylamino-3'-phenyl)-propionyloxy-11(15-->1)-abeotaxa- 4(20),11-diene-9 alpha, 10 beta-diol and 2 alpha-acetoxy-5 alpha-cinnamoyloxy-9 alpha, 10 beta-dihydroxy-taxa- 4(20),11-diene-13-one on the basis of 1D, 2D NMR, and MS spectral analysis.

Diterpenes↗
PubMed1999

Dynamic magnetic resonance imaging of head and neck lesions.

Dynamic magnetic resonance imaging (MRI) has been used to improve the detection of tumors, to determine the tumor extension, and to make differential diagnosis. Most malignant lesions of the head and neck show early enhancement and early washout of contrast media on dynamic MRI, but the tumor characterization remains unclear. Pharmacokinetic analysis of dynamic MRI can provide information about the permeability of Gd-DTPA in the tumor that may reflect the oxygen concentration of the tumor and the amount of drug delivered to the tumor. This information may be useful in the prediction of radiation and/or chemotherapy response of the tumor.

Algorithms↗
PubMed1999

Gadolinium-DTPA-enhanced magnetic resonance imaging and functional outcome in patients with acute myocardial infarction.

This study was designed to test the hypothesis that Gadolinium-diethylenetriamine pentaacetic acid (Gd-DTPA)-enhanced magnetic resonance images (MRI) reflect the severity of ischemic injury during the acute and chronic phases of myocardial infarction (MI). Twenty-nine patients with their first acute MI underwent Gd-DTPA-enhanced MRI in the first week (4.2+/-0.3 days) and at 1 month after onset. Pairs of left ventriculograms were compared with Gd-DTPA-enhanced magnetic resonance images, classified into 3 pattern groups: hyper-enhancement, with and without a central hypo-enhanced region (P1 and P2, respectively), and non-enhancement (P3). In the acute phase of MI, P1 was found in 10, P2 in 11, and P3 in 8 patients. One month later, the image pattern had changed from P1 to P2 in a single patient, from P2 to P3 in 4 patients, and had remained identical in the others. Patients with P3 showed improvement of anterior wall motion in the 1-month follow-up study, and had higher TIMI flow grades and lower peak creatine kinase values than those without recovery. Thus, Gd-DTPA-enhanced magnetic resonance images, closely reflecting the severity of myocardial injury, are useful in predicting myocardial functional recovery after MI.

Adult↗
PubMed1999

A probable relationship between an endogenous digitalis-like substance and concentric cardiac hypertrophy in primary aldosteronism.

A 44-year-old woman was admitted to our hospital due to severe hypertension. An electrocardiogram (ECG) and an echocardiogram showed severe left ventricular hypertrophy. Her plasma aldosterone level was elevated. Magnetic resonance imaging revealed a small mass in the right adrenal gland. Before removal of the tumor, plasma endogenous digitalis-like substance (EDLS) levels were elevated. After removal of the tumor, EDLS levels quickly returned to the normal level. A series of echocardiograms and ECGs over a 6- year period after removal of the tumor showed marked regression of cardiac hypertrophy. These findings suggest that EDLS may be closely related to the development of concentric cardiac hypertrophy in primary aldosteronism.

Adrenal Gland Neoplasms↗
PubMed1999

MR imaging of squamous cell carcinoma of the floor of the mouth. Appearance of the sublingual and submandibular glands.

PURPOSE: To determine the diagnostic value of MR imaging for tumors of the floor of the mouth and the effects of the tumors on the sublingual and submandibular glands. MATERIAL AND METHODS: Thirty-seven patients with proven squamous cell carcinoma of the floor of the mouth underwent MR imaging, including unenhanced T1-weighted, T2-weighted, dynamic, and contrast-enhanced T1-weighted images. The appearance of the tumor and the sublingual and submandibular glands was assessed qualitatively and quantitatively. RESULTS: All tumors demonstrated replacement of the normal signal intensity in the adjacent sublingual gland. Twenty-one patients (57%) had abnormal signal intensity of the submandibular gland without tumor invasion, presumably secondary to submandibular duct obstruction by the tumor. Unenhanced T1-weighted images provided high contrast between tumor and sublingual gland. Tumors limited within the gland were well detected on unenhanced T1-weighted images. Large tumors extending beyond the gland were well delineated on dynamic images, but no better than on T2-weighted images. CONCLUSION: At MR imaging for tumor of the floor of the mouth, one must carefully evaluate the appearance of the sublingual and submandibular glands. Contrast-enhanced studies are unnecessary when the tumor is limited within the sublingual gland on precontrast MR images.

Adult↗
PubMed1999

Hemorrhagic myocardial infarction after coronary reperfusion detected in vivo by magnetic resonance imaging in humans: prevalence and clinical implications.

With the advent of thrombolytic therapy, hemorrhagic myocardial infarction (HMI) has been observed in experimental and human autopsy studies. However, its clinical implications remain undetermined, because of the absence of a reliable method to detect its presence in vivo. This study was designed to evaluate the clinical implications of HMI detected by magnetic resonance (MR) imaging in vivo after coronary reperfusion. Thirty-nine patients with acute myocardial infarction (AMI) were studied. Percutaneous transluminal coronary angioplasty (PTCA) was used to reopen the occluded coronary artery. Electrocardiogram (ECG)-gated T2*-weighted gradient-echo MR imaging was performed to detect intramyocardial hemorrhage, using a 1.5-T magnet within 2 weeks after coronary reperfusion (average, 5.7 days). Thirteen patients (33%) showed intramyocardial hemorrhage as a distinct hypointense zone by gradient-echo MR imaging and 26 patients showed homogeneous intensity consistent with absence of intramyocardial hemorrhage. Coronary angiograms showed lesser development of collateral flow in the patients with HMI than in those without (81% vs. 37%). Infarct size, estimated 1 month after coronary reperfusion by thallium-201 scintigraphy, was larger among patients with HMI than in those without (37 +/- 14% vs. 21 +/- 14%, respectively, p < 0.05). Left ventricular ejection fraction at 1 month follow-up showed less recovery in patients with HMI than in those without (47 +/- 9 to 51 +/- 10%; p = 0.47, vs. 53 +/- 10 to 60 +/- 9%, respectively, p < 0.05). ECG-gated T2*-weighted gradient-echo MR imaging offers a noninvasive means of detection of intramyocardial hemorrhage in patients with reperfused AMI. HMI occurred even after primary PTCA and may be a common finding associated with severely injured myocardium.

Aged↗
PubMed1999

[Endothelial-derived nitric oxide mediates the peripheral vasodilatory effects of amrinone in humans].

Amrinone, which is used for the treatment of acute congestive heart failure, has vasodilatory and positive inotropic effects through the increment of intracellular cyclic adenosine monophosphate. Recent in vitro investigations have shown that amrinone has an endothelium-dependent vasodilatory effect. The present study examined whether amrinone shows this endothelium-dependent vasodilatory effect in human peripheral vessels. Forearm blood flow during intra-arterial infusion of graded doses (12.5, 25, 50, 100, 200 micrograms/min) of amrinone was measured using plethysmography in 10 healthy subjects without organic vascular disease before and after nitric oxide synthase blocking with NG-monomethyl-L-arginine (L-NMMA, 400 mumol). The graded dose of amrinone produced progressive increases in amrinone plasma concentrations, and a dose over 100 micrograms/min caused amrinone plasma concentrations of more than 1.0 microgram/ml. The increase in forearm blood flow in response to amrinone was significantly depressed after L-NMMA doses of less than 100 micrograms/min, but the increase in forearm blood flow during infusion of higher doses (100, 200 micrograms/min) was not affected by L-NMMA. These results suggest that endothelial-derived nitric oxide may partially contribute to amrinone-induced vasodilation in humans. Thus, the vasodilatory effect of amrinone might be impaired in patients with endothelial dysfunction.

Adult↗
PubMed1999

Clinical significance of perfusion imaging of the left atrial wall and structures in its cavity by contrast echocardiography.

This study examined whether myocardial contrast echocardiography (MCE) can visualize left atrial appendage myocardial perfusion using transesophageal echocardiography (TEE) with intracoronary injection of sonicated albumin. We also evaluated blood flow into normal structures (i.e. muscular trabeculae) and abnormal masses (i.e. fresh thrombi and myxomas) within the left atrium by MCE. TEE images were obtained with a biplane or multiplane 5 MHz transducer in 16 patients without significant coronary artery occlusive disease. Left atrial appendage myocardium was divided into 4 segments in both the transverse and longitudinal planes, and contrast opacification of each segment during MCE was visually evaluated by 2 independent observers. Visual assessment of contrast opacification of prominent muscular trabeculae within the left atrial appendage (6 patients), and of left atrial or left atrial appendage thrombi (4 patients), was also performed. The ratio of background-subtracted peak videointensity from muscular trabeculae or thrombi versus left atrial appendage myocardium was determined as corrected peak videointensity. In 3 patients with myxomas, contrast opacification of the tumor was visually assessed. Ninety-six segments of left atrial appendage myocardium were visually analyzed. Contrast opacification of the left atrial appendage myocardium was identified in 92 of 96 segments (96%, 95% confidence interval 0.90-0.98) by Observer 1 and in 91 of 96 segments (95%, 95% confidence interval 0.88-0.98) by Observer 2. MCE also enhanced the imaging of left atrial appendage muscular trabeculae, but not of left atrial or left atrial appendage thrombi. Corrected peak videointensity from thrombi was significantly lower than that from muscular trabeculae (0.15 +/- 0.11 vs 0.95 +/- 0.18, p < 0.05). All myxomas were distinctly opacified by MCE. Transesophageal MCE with intracoronary injection of sonicated albumin can image left atrial appendage myocardial perfusion. MCE allows the evaluation of blood flow into normal structures and abnormal masses within the left atrium.

Adult↗
PubMed1999

Developmental genetics of the Drosophila gut: specification of primordia, subdivision and overt-differentiation.

The Drosophila gut is composed of three major parts, the foregut, midgut and hindgut, which arise from anterior and posterior invaginations of the early blastoderm. We review the process of the specification of the gut primordia, subsequent subdivision and region-specific cell differentiation in terms of developmental genetics. Graded activities of maternal signals at anterior and posterior terminal domains of the blastoderm, being mediated by activities of two zygotic gap genes, tailless and huckebein, lead to the activation of key genes that determine the gut primordia: serpent (GATA factor gene) for the endodermal midgut; brachyenteron (Brachyury homolog) for the ectodermal hindgut. fork head (HNF-3 homolog) and caudal (Cdx homolog) are also essential for the development of all gut primordia or hindgut primordium, respectively. Subdivision of the midgut epithelium is regulated by inductive signals emanating from the visceral mesoderm, which is under the control of HOM-C genes. In contrast, pattern formation of the ectodermal foregut and hindgut is regulated by secreted signaling molecules, such as Wingless (Wnt homolog), Hedgehog and Decapentaplegic (Bmp-4 homolog), as in the case of segmented structures and imaginal discs. Finally, the gut is subdivided into at least 36 compartments that are recognized asminimum tissue units of regional differentiation. A few genes that are responsible for determining and maintaining the state of overt-differentiation of the compartments have also been reported. A marked feature of the genetic mechanism of the gut development is the unexpectedly wide spectrum of the similarities of relevant genes and regulatory pathways of gene expression between Drosophila and vertebrates, which may imply a prototypic style of body plan common to protostomes and deuterostomes.

Animals↗
PubMed1999

[Left ventricular relaxation in lone atrial fibrillation and atrial fibrillation with heart disease].

Atrial fibrillation with organic heart disease shows a steady value for the time constant of left ventricular isovolumetric relaxation (TC), whereas left ventricular contractility varies from beat to beat. However, there is no report on left ventricular relaxation in lone atrial fibrillation. This study assessed left ventricular relaxation in 5 patients with lone atrial fibrillation, 3 with ischemic heart disease and one with hypertrophic cardiomyopathy. Left ventricular pressure was recorded at 3 msec intervals, with a high fidelity micromanometer-tipped catheter. Maximal positive dP/dt (dP/dtmax) and TC of isovolumetric left ventricular relaxation period [P(t) = (P0-P infinity) exp (-t/TC) + P infinity] were measured as indices of left ventricular contractility and left ventricular relaxation, respectively. Correlation coefficients of dP/dtmax and TC versus the ratio of the preceding to the pre-preceding RR-interval (RR2/RR1) were calculated. A good correlation was found between dP/dtmax and RR2/RR1 in all patients (r = 0.71-0.84, p < 0.0001). No correlation between TC and RR2/RR1 was found in patients with atrial fibrillation with organic heart disease, but a good correlation was found between TC and RR2/RR1 in patients with lone atrial fibrillation (r = 0.74-0.95, p < 0.0001). The correlation between TC and RR2/RR1 is well preserved in lone atrial fibrillation. The mechanism of the variation of TC with the RR2/RR1 interval in lone atrial fibrillation may be similar to the change of TC in postextrasystolic potentiation, which is attributed to the change of intracellular Ca2+ concentration. Absence of correlation between TC and RR2/RR1 interval may indicate that left ventricular relaxation is disturbed in patients with atrial fibrillation with organic heart disease.

Aged↗
PubMed1998

Enhanced secretion of insulin plays a role in the development of atherosclerosis and restenosis of coronary arteries: elective percutaneous transluminal coronary angioplasty in patients with effort angina.

OBJECTIVES: We investigated the relation between insulin and coronary atherosclerosis and restenosis of the coronary arteries, by performing elective percutaneous transluminal coronary angioplasty (PTCA). BACKGROUND: Insulin is known to promote atherosclerosis of the arteries and has been implicated in the development of restenosis after PTCA. METHODS: Of 210 angina patients who underwent PTCA, newly detected lesions in 35 consecutive nondiabetic subjects without previous intervention on the same main coronary arteries were analyzed after a 75-g oral glucose tolerance test (OGTT) and follow-up coronary angiography. Atherosclerotic lesions were evaluated by pattern, severity and extent. Restenosis was defined as loss of gain, the percentage of loss of the initial gain in the coronary diameter achieved by PTCA > or = 50%. RESULTS: Patients with restenosis had a significantly higher extent index (a marker of atherosclerosis), insulin area, ratio of insulin area to glucose area, insulinogenic index and minimal lumen diameter after PTCA than those without restenosis (p=0.001, 0.011, 0.002, 0.016 and 0.041, respectively). Simple regression analysis revealed that only the ratio of insulin area to glucose area (a relative marker of enhanced insulin secretion) significantly correlated with the extent index (p=0.035). Extent index, insulin area, the ratio of insulin area to glucose area and insulinogenic index significantly correlated with loss of gain (p=0.001, 0.010, 0.002 and 0.032, respectively). Stepwise multiple regression analyses revealed that extent index and the ratio of insulin area to glucose area significantly correlated with loss of gain. CONCLUSIONS: Enhanced secretion of insulin during the OGTT might be useful as a predictor of coronary atherosclerosis and of restenosis after elective PTCA in nondiabetic patients with effort angina.

Aged↗
PubMed1998

Optimal image resolution for digital storage of radiotherapy-planning images.

PURPOSE: To evaluate the quality of digitized radiation-planning images at different resolution and to determine the optimal resolution for digital storage. METHODS AND MATERIALS: Twenty-five planning films were scanned and digitized using a film scanner at a resolution of 72 dots per inch (dpi) with 8-bit depth. The resolution of scanned images was reduced to 48, 36, 24, and 18 dpi using computer software. Image qualities of these five images (72, 48, 36, 24, and 18 dpi) were evaluated and given scores (4 = excellent; 3 = good; 2 = fair; and 1 = poor) by three radiation oncologists. An image data compression algorithm by the Joint Photographic Experts Group (JPEG) (not reversible and some information will be lost) was also evaluated. RESULTS: The scores of digitized images with 72, 48, 36, 24, and 17 dpi resolution were 3.8 +/- 0.3, 3.5 +/- 0.3, 3.3 +/- 0.5, 2.7 +/- 0.5, and 1.6 +/- 0.3, respectively. The quality of 36-dpi images were definitely worse compared to 72-dpi images, but were good enough as planning films. Digitized planning images with 72- and 36-dpi resolution requires about 800 and 200 KBytes, respectively. The JPEG compression algorithm produces little degradation in 36-dpi images at compression ratios of 5:1. CONCLUSION: The quality of digitized images with 36-dpi resolution was good enough as radiation-planning images and required 200 KBytes/image.

Humans↗
PubMed1998

Acute traumatic injury of the distal descending aorta associated with thoracic spine injury.

A rare case of traumatic injury of the distal descending aorta associated with thoracic spine injury is reported. A 21-year-old man was admitted after a traffic accident. Thoracic CT and angiography demonstrated a false aneurysm of the distal descending aorta and a compression fracture of the eleventh thoracic vertebra. At emergency surgery, a transverse linear tear at the level of the aortic hiatus was confirmed and repaired.

Accidents, Traffic↗
PubMed1998

Mesenteric schwannoma.

Schwannoma is a benign neurogenic tumor arising from the sheath of peripheral nerves. It occurs very rarely in the mesentery, where it is difficult to diagnose. Herein we describe a case in which contrast-enhanced CT and gadolinium-DTPA-enhanced MR showed a locally enhanced well-defined tumor with a cystic component just anterior to the duodenum. These findings corresponded well to the resected specimen.

Contrast Media↗
PubMed1998

Primary leiomyoma of the ovary: a case report.

The imaging features of primary ovarian leiomyoma have seldom been described because of the very low prevalence of the tumor. Herein we present a case report on its magnetic resonance imaging features. Both T1- and T2-weighted images revealed a low-signal-intensity mass, which was well circumscribed and sharply demarcated from the uterus. Magnetic resonance imaging was useful in distinguishing it from a malignant ovarian tumor and uterine leiomyoma.

Diagnosis, Differential↗
PubMed1998

ACE gene polymorphism in childhood IgA nephropathy: association with clinicopathologic findings.

A deletion polymorphism in the angiotensin-converting enzyme (ACE) gene has been reported to be a risk factor for progression to chronic renal failure in immunoglobulin A nephropathy (IgAN). In this study, we investigated the association between ACE gene polymorphism and clinical findings, early biopsy findings such as the extent of mesangial proliferation, focal lesions (capsular adhesions, glomerulosclerosis, and crescents), and the glomerular area in childhood IgAN. Genomic DNA was obtained from 97 patients and control subjects. Gene polymorphisms, consisting of an insertion (I) or deletion (D) of the 287-base pair Alu sequence, were detected using the polymerase chain reaction. The extent of capsular adhesions and glomerulosclerosis was significantly higher in patients with the ID/DD genotypes than in those with the II genotype (ID/DD v II: 8.0%+/-1.4% v 2.5%+/-0.8% [P = 0.017] and 5.1%+/-1.3% v 1.4%+/-0.6% [P = 0.028], respectively). Whereas there was no difference in the extent of mesangial proliferation and crescents between the ID/DD genotypes and the II genotype. Urinary protein excretion at the time of biopsy was significantly greater in patients with the ID/DD genotypes than in those with the II genotype (1.02+/-0.15 g/d/m2 body surface area v 0.56+/-0.13 g/d/m2 body surface area; P = 0.012). These results indicate that ACE gene polymorphism may not influence the extent of mesangial proliferation and crescents that are acute lesions. However, the ID/DD genotypes are associated with chronic lesions, such as capsular adhesions or glomerulosclerosis and urinary protein excretion in childhood IgAN.

Alleles↗