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Biomedical subjects

M Niitsu

Publications and source records attributed to M Niitsu.

At least 55 records · Page 3Linked to original sources
PubMed1994

[Usefulness of superparamagnetic iron oxide particle (AMI-25) enhanced MR imaging for the diagnosis of liver tumors: comparison with contrast enhanced CT].

The purpose of this study was to clarify the usefulness of SPIO-enhanced MRI in the diagnosis of liver tumors in comparison with contrast-enhanced CT. The subjects were forty patients with 154 nodules in the liver. We compared SPIO-enhanced MRI with contrast-enhanced CT in terms of tumor-liver contrast and detectability of liver tumors. In terms of tumor liver contrast, SPIO-enhanced MRI was equal or superior to contrast-enhanced CT in 82% of cases. In the detectability of liver tumor, SPIO-enhanced MRI detected more tumors than contrast-enhanced CT, especially small tumors. Tumors undetected by SPIO-enhanced MRI that were detected by contrast-enhanced CT and/or plain MRI were adenomatous hyperplasia and inflammatory pseudotumor according to fine needle biopsy. There were no severe complications of SPIO-enhanced MRI. In conclusion, SPIO-enhanced MRI will be more useful than contrast-enhanced CT in the diagnosis of liver tumors. SPIO-enhanced MRI may be a promising diagnostic method for the detection of hepatic tumors, especially small ones.

Adult↗
PubMed1994

Acute change of exercised muscle using magnetization transfer contrast MR imaging.

We evaluated the acute changes in exercised muscle using magnetization transfer contrast (MTC) MR imaging with a short repetition time sequence. Ten volunteers performed supine ankle dorsiflexion exercise. MTC gradient-recalled echo (GRE) images were obtained before and after exercise at 1.5 T. The effect of MTC was assessed by dividing the signal intensity on MTC GRE images by that on conventional GRE images (M(s)/M0). The signal intensity, M(s)/M0 and cross-sectional area of exercised muscle were all greater at 1-2 min after exercise than immediately after exercise. We propose that this additional increase in these parameters after exercise was due to physiological reflow or hyperemia. Since the M(s)/M0 showed a good correlation with free water content in exercised muscle, this ratio may provide a quantitative variable for evaluating dynamic change of water-macromolecule interaction in skeletal muscle.

Adipose Tissue↗
PubMed1994

Tongue displacement: visualization with rapid tagged magnetization-prepared MR imaging.

The authors describe a technique to depict tongue muscle displacement with tagged magnetization-prepared gradient-recalled echo magnetic resonance imaging. Three Japanese volunteers (three men, aged 31-36 years) were studied while they articulated specific sounds. Each image was obtained in less than 2 seconds without need for gating. Displacement and alteration of the tags within the tongue muscle during phonation were clearly visible. The technique may prove useful in the study of phoniatric pathophysiology.

Adult↗
PubMed1994

Occurrence of tertiary and quaternary branched polyamines in thermophilic archaebacteria.

Polyamines of thermophilic archaebacteria were analysed by high-performance liquid chromatography and gas chromatography. Thermoplasma acidophilum and Thermoplasma volcanium ubiquitously contained spermidine and spermine. Four species of Sulfolobus, S. acidocaldarius, S. solfataricus, S. metallicus and S. shibatae, two species of Acidianus, A. brierleyi and A. infernus, and Metallosphaera sedula, contained norspermidine and norspermine in addition to spermidine and spermine, but quantitative distribution profiles were species-specific. A tertiary tetra-amine, N4-aminopropylspermidine, and a quaternary penta-amine, N4-bis(aminopropyl)spermidine, were detected as a major polyamine in three species of Thermococcus, T. celer, T. litoralis and T. stetteri, and two Pyrococcus species, P. furiosus and P. woesei. This is the first report on the occurrence of branched polyamines in archaebacteria.

Archaea↗
PubMed1993

[Magnetization transfer contrast imaging of the skeletal muscle in gradient recalled echo sequence].

The human midcalf muscle images were obtained using gradient recalled echo (GRE) sequence with and without magnetization transfer contrast (MTC) sequence. A significant decrease of relative signal intensity was observed in muscle with off-resonance irradiation. The percentage increase of signal intensity after dorsiflexion exercises was 55.6% and 29.0% for MTC-GRE and GRE sequence, respectively. MTC technique might be useful in improving contrast between many tissues as well as muscles.

Adult↗
PubMed1993

An Alkalophilic Bacillus sp. Produces 2-Phenylethylamine.

A large amount of 2-phenylethylamine was produced in cells of alkalophilic Bacillus sp. strain YN-2000. This amine is secreted in the medium during the cell growth. The amounts of 2-phenylethylamine in both cells and medium change upon changing the pH of the medium.

Journal Article↗
PubMed1993

Tertiary and quaternary branched polyamines distributed in thermophilic Saccharococcus and Bacillus.

The distribution of long linear, tertiary and quaternary branched polyamines in twenty thermophilic Gram-positive strains belonging to the genera Saccharococcus, Bacillus or Amphibacillus were analysed by high-performance liquid chromatography and gas chromatography. The extremely thermophilic S. thermophilus contained a tertiary tetra-amine, N4-aminopropylspermidine, a linear penta-amine, thermopentamine, a tertiary penta-amine, N4-aminopropylspermine, and a quaternary penta-amine, N4-bis(amino-propyl)spermidine. N4-aminopropylspermine [NH2(CH2)3N((CH2)3NH2)(CH2)4NH(CH2)3NH2] first found in this study, was also detected in the extremely thermophilic 'B. caldolyticus' and 'B. caldotenax' and the moderately thermophilic B. stearothermophilus, B. smithii and B. thermocatenulatus.

Bacillus↗
PubMed1992

Novel linear and branched polyamines in the extremely thermophilic eubacteria Thermoleophilum, Bacillus and Hydrogenobacter.

Novel tertiary branched tetra-amines, quaternary branched penta-amines, linear penta-amines and linear hexa-amines were distributed as the major polyamines in six obligately extremely thermophilic eubacteria belonging to Thermoleophilum, Bacillus or Hydrogenobacter. The major polyamine of Thermoleophilum album and Thermoleophilum minutum was identified as a quaternary branched penta-amine, 4,4-bis(3-aminopropyl)-1,8-diamino-4-azaoctane (NH2[CH2]3N+([CH2]3NH2)2[CH2]4NH2) by h.p.l.c., t.l.c. and g.c.-m.s. Hydrogenobacter thermophilus and Hydrogenobacter halophilus contained another quaternary branched penta-amine, 4,4-bis(3-aminopropyl)-1,7-diamino-4-azaheptane (NH2[CH2]3N([CH2]3NH2)2[CH2]3NH2) as the major polyamine, and tertiary branched tetra-amines (4-(3-aminopropyl)-1,7-diamino-4-azaheptane (NH2[CH2]3N([CH2]3NH2)[CH2]3NH2), 4-(3-aminopropyl)-1,8-diamino-4-azaoctane (NH2[CH2]3N([CH2]3NH2)[CH2]4NH2)) and 4,4-bis(3-aminopropyl)-1,8-diamino-4-azaoctane were confirmed as minor components. Bacillus schlegelii contained a branched tetra-amine, 4-(3-aminopropyl)-1,8-diamino-4-azaoctane, a branched penta-amine, 4,4-bis(3-aminopropyl)-1,8-diamino-4-azaoctane, a linear penta-amine, 1,16-diamino-4,8,13-triazahexadecane (NH2[CH2]3NH[CH2]3NH[CH2]4NH[CH2]3NH2) and linear hexa-amine(s), 1,20-diamino-4,8,12,17-tetra-azaeicosane (NH2[CH2]3NH[CH2]3NH[CH2]3NH[CH2]4NH[CH2]3NH2 ) and/or 1,20-diamino-4,8,13,17-tetra-azaeicosane (NH2[CH2]3NH[CH2]3NH[CH2]4NH[CH2]3NH[CH2]3NH2 ).

Bacillus↗
PubMed1992

Rapid T1 estimation using tagged magnetization-prepared gradient-echo MR imaging.

A technique for estimation of the longitudinal relaxation time of a large homogeneous object with an acquisition time of 4 s or less was developed by combining spatially selective rf tagging pulses with a T1-weighted magnetization-prepared gradient-echo sequence. Multiple 5-mm-wide tagged areas are laid orthogonal to the imaging section of interest. The contrast between each tag and the untagged regions differs because each tag is produced at a different time. The T1 value is determined from the nulling time at which tagged and untagged areas have no contrast.

Adipose Tissue↗
PubMed1991

[Three-dimensional MR imaging of the knee joint--diagnostic value for meniscal tears].

The value of a three-dimensional (3D) imaging system was evaluated using a newly developed workstation. Fifteen knee joints with meniscal tears confirmed by arthroscopic examinations underwent 3D magnetic resonance (MR) imaging. These 3D data sets were processed into 3D display by multiplanar reformation (MPR) and the volume rendering technique, and the features of the meniscal tears were compared with those on conventional two-dimensional (2D) MR images. The 3D images with MPR provided higher detectability and more descriptive delineation of the meniscal tears than the 2D images. With its powerful image processing capacity, the workstation facilitated high-speed, high-quality 3D display and provided precise views of meniscal cleavages for the planning of surgical treatment. The independent processing system permitted efficient throughput of the MR data and eliminated wasteful filming processes.

Adult↗
PubMed1991

Polyamine distributions in thermophilic eubacteria belonging to Thermus and Acidothermus.

Triamines such as norspermidine, spermidine, and homospermidine and tetraamines such as norspermine, spermine, thermospermine, and aminopropylhomospermidine were found to be distributed ubiquitously in the eight extremely thermophilic (growing at 70 degrees C) Thermus species tested. Three linear pentaamine (caldopentamine, homocaldopentamine, and thermopentamine), two linear hexaamines (caldohexamine and homocaldohexamine), two tertiary branched tetraamines (N4-aminopropylnorspermidine and N4-aminopropyl-spermidine), and quaternary branched pentaamines such as N4-bis(aminopropyl)norspermidine and N4-bis(aminopropyl)spermidine were detected in T. thermophilus HB8, T. filiformis Wai33 A1, T. flavus AT-62, and T. caldophilus GK24. The linear hexaamines and branched polyamines were absent in T. aquaticus YT-1, T. sp. X-1, T. sp. T2, and T. sp. T351, in which linear pentaamines were minor components. Moderately thermophilic Thermus ruber and Thermus sp. K-2 contained putrescine, spermidine, norspermidine, homospermidine, spermine, norspermine, thermospermine, and aminopropylhomospermidine. No pentaamines, hexaamines, or branched polyamines were found in these two moderately thermophilic Thermus species. On the other hand, moderately thermophilic, acidophilic Acidothermus cellulolyticus was devoid of all the polyamines.

Chromatography, High Pressure Liquid↗
PubMed1991

Tears of cruciate ligaments and menisci: evaluation with cine MR imaging.

A cine magnetic resonance (MR) imaging technique, involving the acquisition of kinematic sagittal images during knee movement, was used to evaluate 52 symptomatic knee joints. Results were compared with those obtained by means of static three-dimensional (3D) MR imaging. Twenty-seven of the 28 anterior cruciate ligament (ACL) tears and 22 of 24 normal ligaments were correctly identified at cine MR imaging for a sensitivity of 96% and a specificity of 92%. Static 3D MR imaging yielded a sensitivity of 71% and a specificity of 88%. All four posterior cruciate ligament tears were identified at cine and 3D MR imaging. For meniscal tears, cine MR imaging yielded a sensitivity of 48% and a specificity of 96%; the sensitivity and specificity for 3D MR imaging were 71% and 96%, respectively. Cine MR imaging proved to be more useful than static MR imaging in assessing the tightness of cruciate ligaments, especially of those that were partially torn, and in assessing the movement of meniscal-free fragments. The increased information obtained with cine MR imaging may warrant continued investigation and clinical application.

Adult↗
PubMed1990

Moving knee joint: technique for kinematic MR imaging.

A system for magnetic resonance imaging of the knee joint during movement was developed by using a gating system and cine acquisition. The technique was used in 10 subjects: five with no history of knee pain or injury and five with tears of the anterior cruciate ligament. The normal ligaments and menisci appeared as low-intensity structures against intermediate-intensity hyaline cartilage. The ligament tears appeared discontinuous and faint against the background of the to-and-fro moving joint fluid.

Adult↗
PubMed1990

[MR imaging of the arm].

Thirty arms of healthy adults were studied with MR imaging using surface coil. Fine structures of the arm, such as muscular bundles, small vessels and nerves were clearly demonstrated. Deep fascia dividing muscular bundles appeared as high intensity on T1-weighed image due to fat deposition beneath the fascia. Aponeurosis is also flat sheet of densely arranged collagen fibers. With rather thicker layer of collagen fibers than fascia, aponeurosis appeared as low intensity sheet that was frequently demonstrated on MR images of the extremities.

Adult↗
PubMed1989

[MRI and ultrasonography of cavernous hemangioma of the liver].

The frequency of detection of hemangioma has increased with the improvements of ultrasonography. Sonography detected 24 lesions out of 30 (80%), and 28 lesions out of 30 (93%) by MRI. MRI is superior to ultrasonography in detection rate. In T2 weighted spin echo image, most of the hepatic hemangiomas show moderately or markedly higher intensity than the liver and mildly higher or the same intensity as that of the spleen. MRI will play an important role in determination of necessity of further invasive diagnostic methods such as angiography or biopsy.

Adult↗
PubMed1988

Effect of various polyamine analogs on in vitro polypeptide synthesis.

Various polyamine analogs were examined for their ability to stimulate and to function as sparing agents for the Mg2+ requirement in polypeptide synthesis at various temperatures in Escherichia coli (37 and 47 degrees C) and the extremely thermophilic Thermus thermophilus (60 and 70 degrees C) cell-free systems. The optimal concentration of each polyamine analog increased as the incubation temperature was elevated. At a fixed temperature, the optimal concentration of polyamine analogs was in the order diamines greater than triamines greater than tetraamines greater than pentaamines. All diamines tested stimulated polypeptide synthesis almost equally but lowered the optimal Mg2+ concentration in the order diaminopropane greater than putrescine greater than cadaverine. The degree of diamine stimulation was maximal at 37 degrees C. The effects of three triamines were very similar in the E. coli system but in the T. thermophilus system spermidine was most effective in stimulation of polypeptide synthesis. From the results of experiments using tetraamines and pentaamines, it was deduced that the presence of both aminobutyl and aminopropyl groups in polyamine analogs is important for stimulation of polypeptide synthesis. In the E. coli system, triamines were the most effective polyamines for stimulation of polyphenylalanine synthesis at both 37 and 47 degrees C, while, in the T. thermophilus system, thermospermine, a tetraamine, was most effective at 60 degrees C and 3,4,4,3-pentaamine was most effective at 70 degrees C.

Cell-Free System↗