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Biomedical subjects

M Fukunaga

Publications and source records attributed to M Fukunaga.

At least 307 records · Page 17Linked to original sources
PubMed1990

Factors influencing the enhanced hypocalcemic action of liposome-entrapped calcitonin.

The mechanism whereby liposomal entrapment enhances the hypocalcemic effect of calcitonin (CT) was evaluated in the rat. Phosphatidylcholine (PC) and PC plus cholesterol (PCC) preparations of large multilammelar vesicles (MLV) and small unilammelar vesicles (SUV) were used to entrap human calcitonin (hCT). The effect of each of these preparations was assessed by measuring plasma calcium after their parenteral administration. Changes in calcium were compared with plasma concentrations of liposomal hCT (L-hCT) and free hCT (F-CT). The plasma form of hCT was also evaluated by gel filtration chromatography. Most of the liposomal preparations had a greater hypocalcemic effect than unencapsulated hCT. Following I.V. administration, the MLV-hCT preparations had the greatest hypocalcemic effect. Thus, to enhance the hypocalcemic effect of hCT, large vesicular size is important for I.V. administration and the absence of cholesterol in the liposome is important for I.M. administration. In general, the greatest hypocalcemic effect was achieved by those liposomal preparations that resulted in the most sustained increase of L-hCT and F-hCT in plasma. Thus, liposomal entrapment enhances the hypocalcemic effect of hCT by prolonging the presence of the peptide in the peripheral circulation.

Animals↗
PubMed1990

Iodine-131 uptake in a patient with thyroid cancer and rheumatoid arthritis during acupuncture treatment.

A patient with thyroid carcinoma had abnormal accumulation of I-131 in the areas of both feet and hands on whole body scan. The sites of abnormal accumulation of I-131 were similar to those on bone scintigraphy. The radiographic examination of the lesions showed characteristic findings of rheumatoid arthritis, and the presence of small gold needles for acupuncture treatment was demonstrated. There were no findings of bone metastases. Although the mechanism of accumulation of I-131 in this patient is unknown, interpreters of I-131 whole body scintigraphs should keep this case in mind when acupuncture treatment has been done. The authors can only speculate on a common blood flow mechanism for enhanced HMDP and I-131 uptake in this arthritic patient who had been treated by acupuncture.

Acupuncture Therapy↗
PubMed1990

Linkage of ribosomal RNA genes in Leptospira.

We determined the linkage of 16S, 23S, and 5S rRNA genes in several strains of Leptospira and Leptonema by DNA-DNA hybridization. Almost all the hybridizations in all leptospires used in these experiments gave two radioactive bands and the results strongly suggest that the number of the 16S and the 23S rRNA genes in those strains is two, respectively. In contrast with the larger rRNAs, the number of 5S rRNA gene was different. In the strains of leptospires, L. biflexa, which were non-parasitic, there are two genes for 5S rRNA, whereas only one gene for 5S rRNA is carried in L. interrogans, which were originally isolated as parasitic. Southern hybridization experiments suggest that those rRNA genes are interspersed on the leptospiral chromosome.

DNA, Bacterial↗
PubMed1990

Cloning of genes for a hemolytic factor of Leptospira interrogans serovar autumnalis strain Congo 21-543.

A DNA fragment encoding a hemolytic factor was cloned from the parasitic spirochete Leptospira interrogans serovar autumnalis strain Congo 21-543. Initial clones were isolated by screening a genomic library in pBR322 in Escherichia coli for hemolytic activity. Hemolytic activity was coded by a 4.5 kilobase BamHI-HindIII fragment. Southern hybridization with DNAs from other strains of Leptospira using this gene as a probe showed that DNAs from non-parasitic strains failed to hybridize with the probe, whereas those from all parasitic strains tested had the sequence which hybridize to the probe.

Cloning, Molecular↗
PubMed1990

Isolation and characterization of the 5S rRNA gene of Leptospira interrogans.

The gene encoding the 5S rRNA for Leptospira interrogans serovar canicola strain Moulton was isolated and sequenced. The 5S rRNA gene occurs as a single copy within the genome and encodes a 117-nucleotide-long RNA molecule. The 5S rRNA gene is flanked at both the 5' and 3' ends by regions of A + T-rich sequences, and the 5'-flanking region contains a promoter sequence. L. interrogans has a unique and remarkable organization of the 5S rRNA gene. The 5S rRNA molecule exhibits a strong similarity to typical eubacterial 5S rRNA in terms of overall secondary structure, while the primary sequence is conserved to a lesser degree. Restriction analysis of the 5S rRNA gene indicated that the DNA sequence including the 5S rRNA gene is highly conserved in the genomes of parasitic leptospires.

Base Sequence↗
PubMed1990

Ga-labeling of immunoglobulin G with high specific radioactivity.

To obtain radiogallium labeled immunoglobulin G with a high specific radioactivity for in vitro use, a 67Ga source was purified by extraction from 67Ga-gallium citrate with butyl acetate, and a 67Ga-labeling solution was produced. This solution was then used to label a deferoxamine-immunoglobulin G conjugate. Both a very high specific radioactivity (872 +/- 56 MBq/mg) and a high labeling efficiency (94.0%) were achieved.

Gallium Radioisotopes↗
PubMed1990

[Multiple extra-osseous accumulation of 99mTc-phosphorous compounds bone scintigraphy in small cell lung cancer associated with hypercalcemia].

Bone scintigraphy was performed in a patient with lung cancer of small cell. On bone scintigraphy the increased accumulations in kidneys were observed, while no findings of multiple skeletal accumulations suspected of bone metastases were observed. Four weeks later, when hypercalcemia has been advanced, on repeated bone scintigraphy the extra-skeletal accumulations in such as lung, heart and stomach were shown. These findings indicated that the cause of hypercalcemia in this case was due to not bone metastases but humoral hypercalcemia which the osteolytic substance was produced from tumor. In present paper, the usefulness of bone scintigraphy in hypercalcemia with malignancy, and the mechanism of hypercalcemia have been described and discussed.

Bone and Bones↗
PubMed1990

[Bone mineral determination using dual energy X-ray absorptiometry (DEXA)].

To quantify the appendicular and axial bone mineral with good accuracy and precision, dual energy X-ray absorptiometry (DEXA), DCS-600 (Aloka) for the radius, mainly composed of cortical bone, and QDR-1000 (Hologic) for the lumbar vertebrae, mainly composed of trabecular bone, was used. Bone loss with aging was earlier in females than that in males, and it was also more prominent in the lumbar vertebrae than that in the radius. Furthermore, the vertebral fracture rate could be evaluated by calculating percentile of an individual bone mineral density to the peak bone mass. Thus, the bone mineral determination using DEXA in both the appendicular and axial bone will provide a useful information in the assessment of bone loss, and the detection of the patients with high risk of fracture in osteoporosis.

Absorptiometry, Photon↗
PubMed1989

Increased accumulation of N-isopropyl-p-(123I)-iodoamphetamine in two cases with mitochondrial encephalomyopathy with lactic acidosis and strokelike episodes (MELAS).

We present two cases with mitochondrial encephalopathy with lactic acidosis and strokelike episodes (MELAS), which showed both increased and decreased accumulation of N-isopropyl-p-(123I)-iodoamphetamine (123I-IMP) in single photon emission computed tomography (SPECT). The increased accumulation of the tracer occurred, before low density appeared on conventional computed tomography, suggesting that 123I-IMP SPECT may be useful in pathophysiological study of MELAS.

Acidosis, Lactic↗
PubMed1989

Activation of human CD8+ suppressor T cells by an antigen-specific CD4+ T-cell line in vitro.

We generated an antigen (streptococcal cell wall antigen)-specific T-cell line from peripheral blood mononuclear cells of a healthy donor with an intermediate response to streptococcal cell wall antigen. Proliferation of the T-cell line was completely blocked by a monoclonal antibody to HLA-DR. This line activated autologous CD8+ T cells in an antigen-specific manner in the presence of autologous monocytes. This activation was mediated by a factor derived from this line and was blocked by a monoclonal antibody against HLA class I molecules. The resultant CD8+ T blasts showed antigen-nonspecific suppression but no cytolytic activity. This antigen-specific generation of the CD8+ T-cell line in vitro by the antigen-specific CD4+ T-cell line is expected to contribute to analyses of functions of CD8+ T-cell subsets, particularly in the down-regulating system, at both cellular and molecular levels.

Antibodies, Monoclonal↗
PubMed1989

Mechanism of action of angiotensin II on isolated rat glomeruli.

Angiotensin II (Ang II) regulates glomerular filtration rate by contracting mesangial cells and thereby decreasing glomerular filtration surface area. To elucidate the cellular mechanism of this action, we investigated the roles of Ca and protein kinase C (PKC) activation in Ang II-induced glomerular capillary vasoconstriction using 3H-inulin to measure the extracellular (largely intracapillary) volume of isolated decapsulated rat glomeruli. Ang II (1 microM) rapidly decreased the glomerular inulin space (GIS), bringing about a maximal decrease at five minutes, which lasted up to 30 minutes. When incubated in 0.5 mM EGTA-containing Ca-free medium or in the presence of 1 microM diltiazem or verapamil, the sustained phase (after 7 min) was completely inhibited. The initial effect (at 3 and 5 min) was only partially inhibited by these maneuvers but was completely inhibited by trifluoperazine or W-7, which indicated that it was dependent on calmodulin and, accordingly, on Ca probably released from the intracellular store. The sustained effect was mimicked by 12-0-tetradecanoylphorbol-13-acetate (TPA) in the presence of extracellular Ca, but was not in its absence. The sustained effect was also inhibited by H-7, an inhibitor of PKC, and by W-7, which indicated that PKC activation and influx of extracellular Ca are both important. Combined treatment with A23187 and TPA could mimic both the initial and sustained effect of Ang II in the presence of extracellular Ca, though either one of them failed to do so when used alone. These results suggest that the initial effect of Ang II on GIS is mediated by Ca released from the intracellular store, on the one hand, and the sustained effect by extracellular Ca influx and PKC activation, on the other.

Angiotensin II↗
PubMed1989

New perspectives for diagnosis of nodular goiter by technetium-thallium subtraction scanning.

To improve the scintigraphic differential diagnosis of thyroid nodules, Tc-99m pertechnetate-Tl-201 Cl subtraction scintigraphy (Tc-Tl subtraction scanning) was performed in 106 patients with various histologically proven thyroid nodules. Results were evaluated by comparison with surgical findings and preoperative ultrasonographic results. Thyroid nodules were more successfully detected by Tc-Tl subtraction scanning than by either Tc-99m pertechnetate or Tl-201 Cl scintigraphy alone. Detection of nodules was further improved when images recorded by the three methods were integrally observed (sensitivity 83%, accuracy 89%), with detectability approaching that of ultrasonography. False-positive or -negative Tc-Tl subtraction scans were obtained principally when multiple nodules were present (7 cases) or when no discrepancy existed between the accumulations of Tc-99m pertechnetate and Tl-201 Cl (18 cases). Most colloid nodules exhibited irregular margins, heterogeneous internal accumulations of Tl-201 Cl, and distorted shapes on Tc-Tl subtraction scans, while the majority of adenoma were oval-shaped with smooth margins. Carcinoma were characterized by homogeneous internal accumulation of Tl-201 Cl and distorted shapes.

Diagnosis, Differential↗
PubMed1989

Endothelin-1 receptors in rat renal glomeruli.

Renal glomeruli form a dynamic structure capable of regulating the glomerular filtration rate (GFR). To explore possible regulating effects of endothelin-1 (ET-1) upon glomerular functions, the presence of specific ET-1 receptors and the biological actions of ET-1 were studied in isolated rat renal glomeruli. The specific binding of [125I]ET-1 to glomeruli was time and temperature dependent. Scatchard analysis of the binding data indicated the presence of a single class of high-affinity binding sites with the apparent dissociation constant of 8.3 nM and the maximal binding capacity of 1.5 pmol/mg protein. ET-1 stimulated prostaglandin (PG) E2 production in glomeruli with the time course and the concentration dependency similar to those found in [125I]ET-1 binding to glomeruli. These results indicate the presence of high-affinity binding sites for ET-1 linked to PGE2 production in glomeruli, suggesting a possible role of ET-1 in the regulation of glomerular function.

Animals↗