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Biomedical subjects

T Murakami

Publications and source records attributed to T Murakami.

At least 721 records · Page 40Linked to original sources
PubMed1996

Genetic variability of the common nod gene in soybean bradyrhizobia isolated in Thailand and Japan.

To determine the taxonomic relationship between Thai soybean bradyrhizobia and soybean bradyrhizobia from other regions, a total of 62 Bradyrhizobium strains were isolated in Thailand. The genetic diversity of the strains was examined with reference to 46 Japanese and 15 USDA strains. The degree of sequence divergence in and around common nod gene regions of the 123 strains was estimated by restriction fragment length polymorphism analysis using the Bradyrhizobium japonicum USDA 110 common nodDYABC gene probe. The phylogenetic grouping of the strains resulted in four major clusters. Cluster 1 comprised the Japanese and USDA strains, which originated in temperate regions, whereas clusters 3 and 4 comprised the tropical Thai strains. Cluster 1 strains comprised the DNA homology groups I and Ia, and hence, were classified as B. japonicum. Cluster 2 strains were in the DNA homology group II, and hence, were classified as Bradyrhizobium elkanii. Clusters 3 and 4 strains, however, did not correspond to any known DNA homology groups. These results indicate that Thai soybean bradyrhizobia are distantly related to B. japonicum and B. elkanii.

Bacterial Proteins↗
PubMed1996

A new silicon detector telescope for measuring the linear energy transfer distribution over the range from 0.2 to 400 keV/micrometer in space.

A new telescope consisting of three two-dimensional position-sensitive silicon detectors which can measure the linear energy transfer (LET) distribution over the range from 0.2 to 400keV/micrometers has been developed as a real-time radiation monitor in manned spacecraft. First, the principle of LET measurement and its design method are described. Second, suitable electronic parameters for the LET measurement are experimentally determined. Finally the telescope performance is investigated by using, relativistic heavy ions. The first in-flight test of this type of telescope on the US Space Shuttle (STS-84) is scheduled for May, 1997.

Astronomy↗
PubMed1996

Liver necrosis and regeneration after fulminant hepatitis: pathologic correlation with CT and MR findings.

PURPOSE: To characterize computed tomographic (CT) and magnetic resonance (MR) findings of liver necrosis and regeneration after fulminant hepatitis. MATERIALS AND METHODS: Three patients with fulminant hepatitis underwent CT before orthotopic liver transplantation; one also underwent MR imaging. These findings were retrospectively reviewed and compared with gross and histologic findings obtained after transplantation. RESULTS: Regions of liver necrosis demonstrated low attenuation on CT scans before contrast material was administered and enhanced to attenuation equal to or greater than that of liver regeneration on postcontrast CT images. Conversely, nodular liver regeneration demonstrated hyperattenuation on precontrast and hypoattenuation on postcontrast CT images, which simulated neoplastic lesions. The necrotic liver parenchyma was seen as high and low intensity on T2- and T1-weighted MR images, respectively, whereas areas of regeneration appeared as hypo- and hyperintense. CONCLUSION: Characteristic patterns of liver regeneration after fulminant hepatitis may be seen at CT and MR imaging. Recognition of this regeneration process may avoid an incorrect diagnosis of malignancy.

Acute Disease↗
PubMed1996

Cirrhosis of the liver: MR imaging with mangafodipir trisodium (Mn-DPDP).

PURPOSE: To evaluate the usefulness of manganese (II) N,N'-dipyridoxylethylenediamine-N,N'-diacetate 5,5'-bis(phosphate) (Mn-DPDP) in magnetic resonance (MR) imaging of cirrhotic livers. MATERIALS AND METHODS: Fifty-eight patients (mean age, 58.8 years), 29 with and 29 without cirrhosis, underwent MR imaging before and after intravenous administration of 5 mumol/kg Mn-DPDP. Enhancement effects were assessed quantitatively and qualitatively. Histologic confirmation was obtained in 51 patients. RESULTS: Liver parenchyma in both patient groups enhanced significantly on T1-weighted spin-echo and gradient-recalled-echo (GRE) images (P < .01). However, cirrhotic livers enhanced significantly less than noncirrhotic livers on T1-weighted GRE images (P < .05). Fourteen cirrhotic livers had heterogeneous enhancement of parenchyma; enhancement was more prominent on GRE images. Decreased enhancement was seen in patients with confluent fibrosis (n = 5), diffuse fibrosis (n = 6), and siderotic regenerating nodules (n = 4). Increased enhancement was seen in patients with benign regenerating nodules (n = 4). CONCLUSION: Mn-DPDP is useful in patients with cirrhosis.

Case-Control Studies↗
PubMed1996

Hepatocellular carcinoma: MR imaging with mangafodipir trisodium (Mn-DPDP).

PURPOSE: To determine the efficacy of manganese (II) N,N'-dipyridoxylethylenediamine-N,N'-diacetate 5,5'-bis(phosphate) (DPDP) at magnetic resonance (MR) imaging for evaluation of hepatocellular carcinoma (HCC). MATERIALS AND METHODS: MR imaging at 1.5 T was performed in 20 patients with 65 HCC nodules. T1- and T2-weighted spin-echo and T1-weighted gradient-recalled-echo images were obtained before and after administration of 5 mumol/kg Mn-DPDP. Readers individually evaluated the pre- and postcontrast images for detection of tumor nodules, with subsequent consensus reading for interpretation discrepancies. Quantitative measurements of tumor-liver contrast-to-noise ratio (C/N) were also performed. Enhancement characteristics were correlated with histologic tumor differentiation. RESULTS: Precontrast images depicted 50 lesions in 17 patients, and postcontrast images depicted 49 lesions in 20 patients. Combination of pre- and postcontrast images enabled detection of 53 lesions in 20 patients. Three lesions (three patients) were seen only on postcontrast images. Four lesions (three patients) were seen only on precontrast images. Reader evaluation of tumor conspicuity showed a significant preference for precontrast T2-weighted SE images (P < .01). Quantitative evaluation showed a significant increase in C/N on postcontrast T1-weighted images (P < .01). Well-differentiated lesions showed significantly greater enhancement than that of poorly differentiated lesions (P < .05). CONCLUSION: Mn-DPDP-enhanced MR imaging depicts HCC tumors not visualized with unenhanced studies. The degree of tumor enhancement correlates with histologic differentiation.

Adult↗
PubMed1996

Hepatic malignancies: usefulness of acquisition of multiple arterial and portal venous phase images at dynamic gadolinium-enhanced MR imaging.

PURPOSE: To determine whether liver tumor detection is increased by acquiring multiple dynamic arterial phase and portal venous phase magnetic resonance (MR) images. MATERIALS AND METHODS: Dynamic MR imaging was performed in 205 patients at 1.5 T with use of a fast spoiled gradient-echo technique (repetition time, 9-12 msec; echo time, 2.1-3.0 msec; flip angle, 30 degrees). During intravenous bolus injection of gadopentetate dimeglumine or gadoteridol (0.1 mmol/kg), nine images were acquired at each of 10-12 locations over approximately 120 seconds. The number of tumors detected on arterial phase and portal venous phase images and unenhanced T1- and T2-weighted spin-echo (SE) images was evaluated separately. Data obtained in 75 patients with proved malignancies were analyzed. RESULTS: At imaging, 220 malignant tumor nodules were depicted. At prospective review of all images, 110 hepatocellular carcinomas (HCCs) were detected: 82 (75%) on unenhanced T1-weighted SE images, 83 (75%) on unenhanced T2-weighted SE images, 92 (84%) on arterial phase images, and 76 (69%) on portal venous phase images. At prospective review, eight HCCs were detected on only arterial phase images, one on only portal venous phase images, nine on both arterial and portal venous phase images, and 11 on only unenhanced SE images. The 18 additional HCCS detected prospectively on only dynamic images increased HCC detection by 21% over prospective detection on only SE images. Detection of non-HCC tumors (including metastases) did not increase with dynamic images. CONCLUSION: Acquisition of multiple dynamic arterial phase and portal venous phase images increased detection of HCC but not metastases.

Adult↗
PubMed1996

Glycogen depletion of the intrafusal fibers in a mouse muscle spindle during prolonged swimming.

This study investigated the recruitment of different types of intrafusal fibers during prolonged swimming at 60-75% of VO2max. We used 56 male adult mice and examined depletion of glycogen in soleus (Sol) and extensor digitorum longus (EDL) muscle spindles by visual inspection and a newly developed optical scanning method. More than 80% of all spindles from six mice consisted of four fibers: one type I nuclear bag (bag1) fiber, one type II nuclear bag (bag2) fiber, and two nuclear chain fibers. Glycogen content was estimated in muscle fibers from groups of six mice that had rested or swum for either 0.5, 1, 2, 4, or 8 h. The optical scanning intensity of periodic acid Schiff (PAS)-stained sections was correlated with their biochemically determined glycogen content (r = 0.93). Both methods showed fundamentally the same result: each type of intrafusal fiber has its own typical recruitment pattern during exercise. In the initial phase (0-0.5 h), glycogen depletion was largest in nuclear bag1 fibers and insignificant in the bag2 and chain fibers. With the bag1 fibers having become fatigued, nuclear bag2 fibers mainly took over during the middle phase (2-4 h). During the last phase (4-8 h), only the glycogen content of chain fibers decreased significantly (4-8 h). There were significant correlations between the recruitment pattern of bag1 and extrafusal type I fibers in both Sol and EDL, between nuclear bag2 and type IIa fibers in Sol, and between nuclear chain and type IIb fibers in EDL. This suggests that, during moderately intense exercise, glycogen depletion occurs first in the slow, then the intermediate, and, finally, the fast intrafusal fibers.

Animals↗
PubMed1996

3DFT-flash MR imaging of pancreatic cancer with gadopentetate dimeglumine.

PURPOSE: We evaluated the usefulness of dynamic 3-dimensional Fourier transformation (3DFT) fast low angle shot (FLASH) MR imaging using gadopentetate dimeglumine (Gd-DTPA) to assess the extent of pancreatic cancer. MATERIAL AND METHODS: Breath-hold 3DFT-FLASH MR images (20/4; 25 degrees flip angle; 7 partitions; 3-5-mm slice thickness) were obtained before the ++administration of 0.1 mmol/kg of Gd-DTPA, just after (early phase), and 1 and 2 min (late phases) after in 14 patients with pancreatic cancer. All patients underwent surgical removal or laparotomy. We compared the findings of T1-, T2-, and postcontrast T1-weighted spin-echo (conventional SE) and 3DFT-FLASH imaging with histologic or surgical findings. RESULTS: Dynamic MR images could delineate the pancreatic tumors more clearly than the conventional SE images, and were useful for diagnosing vessel invasion. The contrast-to-noise ratio between the pancreatic cancer and the surrounding pancreatic parenchyma was significantly higher with the dynamic 3DFT-FLASH image than with the conventional SE images (p<0.01). CONCLUSION: Dynamic 3DFT-FLASH MR imaging with Gd-DTPA is useful in delineating and evaluating the extent of pancreatic cancer.

Adult↗
PubMed1996

MR evaluation of mediopatellar plica.

PURPOSE: Evaluation of the usefulness of MR imaging for diagnosing mediopatellar plica (MP) of the knee joint. MATERIAL AND METHODS: We prospectively examined MR images of 40 knee joints in 30 patients with symptoms. The pulse sequences were SE T1-weighted images (600/26 ms), T2-weighted images (1800/70), and FLASH images (320/15/flip angle 90 degrees). When a low-intensity band was found above the medial condyle of the femur on T1-weighted and T2-weighted MR images, we defined it as MP. We compared these MR findings with arthroscopic findings, including the SAKAKIBARA classification of MP. RESULTS: In 29 of the 40 knee joints in which MP was arthroscopically found, 27 were correctly diagnosed as having MP on MR. In the remaining 11 without MP, 9 were correctly diagnosed by MR. CONCLUSION: MR images are useful not only for detecting MP but also for evaluating its extension. Our results suggest that MR imaging is useful as a screening method for detecting MP before arthroscopy.

Adolescent↗
PubMed1996

Developmental regulation of zebrafish MyoD in wild-type, no tail and spadetail embryos.

We describe the isolation of the zebrafish MyoD gene and its expression in wild-type embryos and in two mutants with altered somite development, no tail (ntl) and spadetail (spt). In the wild-type embryo, MyoD expression first occurs in an early phase, extending from mid-gastrula to just prior to somite formation, in which cells directly adjacent to the axial mesoderm express the gene. In subsequent phases, during the anterior-to-posterior wave of somite formation and maturation, expression occurs within particular regions of each somite. In spt embryos, which lack normal paraxial mesoderm due to incorrect cell migration, early MyoD expression is not observed and transcripts are instead first detected in small groups of trunk cells that will develop into aberrant myotomal-like structures. In ntl embryos, which lack notochords and tails, the early phase of MyoD expression is also absent. However, the later phase of expression within the developing somites appears to occur at the normal time in the ntl mutants, indicating that the presomitogenesis and somitogenesis phases of MyoD expression can be uncoupled. In addition, we demonstrate that the entire paraxial mesoderm of wild-type embryos has the potential to express MyoD when Sonic hedgehog is expressed ubiquitously in the embryo, and that this potential is lost in some of the cells of the paraxial mesoderm lineage in no tail and spadetail embryos. We also show that MyoD expression precedes myogenin expression and follows or is coincident with expression of snaill in some regions that express this gene.

Amino Acid Sequence↗
PubMed1996

Oral administration of insulin as poly(vinyl alcohol)-gel spheres in diabetic rats.

The oral administration of insulin in poly(vinyl alcohol)-gel spheres (PVA-GS), an oral dosage form with prolonged residence time in the ileum, was examined in streptozotocin-induced diabetic rats. Intragastric administration of PVA-GS containing insulin and a protease inhibitor, aprotinin or bacitracin, caused a significant and prolonged reduction of blood glucose levels, suggesting insulin absorption. The bioavailability of insulin estimated from the hypoglycemic effect was about 2% in the presence of either protease inhibitor. The release profiles of insulin and the protease inhibitors from the PVA-GS could be explained by Higuchi's plot, and the rates were similar to each other. The site dependency of insulin absorption in the intestinal tract was examined by an in situ loop method. Insulin absorption estimated by plasma insulin levels was larger in the ileum and the large intestine than in the jejunum. The prolonged residence time of PVA-GS in the absorption site, the lower intestine, and the synchronous release of insulin and the protease inhibitors from the PVA-GS are the two major explanations for the improved bioavailability of insulin administered as PVA-GS containing a protease inhibitor.

Administration, Oral↗
PubMed1996

Medicinal foodstuff. III. Sugar beet. (1): Hypoglycemic oleanolic acid oligoglycosides, betavulgarosides I, II, III, and IV, from the root of Beta vulgaris L. (Chenopodiaceae).

Betavulgarosides I, II, III, and IV, oleanolic acid oligoglycosides having an unique acidic substituent, were isolated from the root of Beta vulgaris L. (sugar beet) together with betavulgarosides VI, VII, and VIII. The chemical structures of betavulgarosides I, II, III, IV were identified from chemical and physicochemical evidence. Betavulgarosides II, III, and IV were found to exhibit hypoglycemic activity in an oral glucose tolerance test in rats.

Animals↗
PubMed1996

Bioactive saponins and glycosides. II. Senegae Radix. (2): Chemical structures, hypoglycemic activity, and ethanol absorption-inhibitory effect of E-senegasaponin c, Z-senegasaponin c, and Z-senegins II, III, and IV.

Following the characterization of E-senegasaponins a and b and Z-senegasaponins a and b, new bioactive saponins named E-senegasaponin c and Z-senegasaponin c were isolated from Senegae Radix, the root of Polygala senega L. var. latifolia TORREY et GRAY., together with Z-senegins II, III, and IV. The chemical structures of E and Z-senegasaponins c and Z-senegins II, III, and IV were elucidated on the basis of chemical and physicochemical evidence, and the geometrical isomeric structures of the 4"-methoxycinnamoyl and 3",4"-dimethoxycinnamoyl groups in these saponins were found to show tautomer-like behavior under irradiation with fluorescent lamps. E and Z-Senegasaponins c and E and Z-senegins II, III, and IV were found to exhibit hypoglycemic activity in the oral D-glucose tolerance test. (E) and (Z)-Senegins II also showed an inhibitory effect on alcohol absorption in rats.

Absorption↗
PubMed1996

Bioactive saponins and glycosides. III. Horse chestnut. (1): The structures, inhibitory effects on ethanol absorption, and hypoglycemic activity of escins Ia, Ib, IIa, IIb, and IIIa from the seeds of Aesculus hippocastanum L.

Five bioactive triterpene oligoglycosides named escins, Ia, Ib, IIa, IIb, and IIIa were isolated from the seeds of horse chestnut tree, Aesculus hippocastanum L. (Hippocastanaceae). The chemical structures of escins Ia, Ib, IIa, IIb, and IIIa were determine on the basis of chemical and physicochemical evidence, which included selective cleavage of the glucuronide linkage using photochemical reaction and lead tetraacetate decarboxylation reaction. Escins Ia, Ib, IIa, and IIb were found to exhibit an ethanol absorption-inhibitory effect and hypoglycemic activity in the oral glucose tolerance test in rats. Some structure-activity relationships are reported.

Animals↗
PubMed1996

Bioactive saponins and glycosides. IV. Four methyl-migrated 16,17-seco-dammarane triterpene gylcosides from Chinese natural medicine, hoveniae semen seu fructus, the seeds and fruit of Hovenia dulcis THUNB.: absolute stereostructures and inhibitory activity on histamine release of hovenidulciosides A1, A2, B1, and B2.

Four bioactive methyl-migrated 16,17-seco-dammarane type triterpene glycosides called hovenidulciosides A1, A2, B1, and B2 were isolated from a Chinese natural medicine, Hoveniae Semen Seu Fructus, the seeds and fruit of Hovenia dulcis THUNB. (Rhamnaceae) together with hoduloside III and (+)-gallocatechin. The absolute stereostructures of hovenidulciosides A1, A2, B1, and B2 have been elucidated by chemical and physicochemical evidence. All were found to inhibit the histamine release from rat peritoneal exudate cells induced by compound 48/80 and calcium ionophore A-23187.

Animals↗
PubMed1996

Bioactive saponins and glycosides. V. Acylated polyhydroxyolean-12-ene triterpene oligoglycosides, camelliasaponins A1, A2, B1, B2, C1, and C2, from the seeds of Camellia japonica L.: structures and inhibitory activity on alcohol absorption.

Acylated polyhydroxyolean-12-ene triterpene oligoglycosides, camelliasaponins A1, A2, B1, B2, C1, and C2, were isolated from the seeds of Camellia japonica L. The structures of six camelliasaponins were elucidated on the basis of chemical and physicochemical evidence. Camelliasaponins B1, B2, C1, and C2 were found to exhibit inhibitory activity on ethanol absorption. By comparison of the inhibitory activities for camelliasaponins with those for desacyl-camelliasaponins, acyl groups such as the angeloyl or tigloyl group were found to be essential to exerting the activity.

Animals↗
PubMed1996

Bioactive saponins and glycosides. VI. Elatosides A and B, potent inhibitors of ethanol absorption, from the bark of Aralia elata SEEM. (Araliaceae): the structure-requirement in oleanolic acid glucuronide-saponins for the inhibitory activity.

Potent inhibitors of ethanol absorption, elatosides A and B, were isolated from the bark of Aralia elata SEEM, through bioassay-guided separation together with elatosides C and D and four known oleanolic acid glucuronide-saponins, spinasaponin A, spinasaponin A 28-O-glucoside, and stipuleanosides R1 and R2. The structures of elatosides A, B, C, and D were determined on the basis of chemical and physicochemical evidence as oleanolic acid 3-O-¿[beta-D-xylopyranosyl (1-->2)] [beta-D-galactopyranosyl (1-->3)]¿-beta-D-glucopyranosiduronic acid, oleanolic acid 3-O-¿[beta-D-galactopyranosyl (1-->2)] [beta-D-galactopyranosyl (1-->3)]¿-beta-D-glucopyranosiduronic acid, and their 28-O-glucopyranosyl esters, respectively. The inhibitory effect of various oleanolic acid 3, 28-O-bisdesmosides, oleanolic acid 3-O-monodesmosides, and oleanolic acid on ethanol absorption was examined and it was found that the 3-O-glucuronide moiety and the 28-carboxyl group in oleanolic acid glucuronide-saponin were required to exert the inhibitory activity.

Animals↗