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Biomedical subjects

S Maeda

Publications and source records attributed to S Maeda.

At least 343 records · Page 19Linked to original sources
PubMed1997

Does endothelin-1 participate in the exercise-induced changes of blood flow distribution of muscles in humans?

Endothelin-1 (ET-1) is an endothelium-derived potent vasoconstrictor peptide that potentiates contractions to norepinephrine in human vessels. We previously reported that the circulating plasma concentration of ET-1 is significantly increased after exercise (S. Maeda, T. Miyauchi, K. Goto, and M. Matsuda. J. Appl. Physiol. 77: 1399-1402, 1994). To study the roles of ET-1 during and after exercise, we investigated whether endurance exercise affects the production of ET-1 in the circulation of working muscles and nonworking muscles. Male athletes performed one-leg cycle ergometer exercise of 30-min duration at intensity of 110% of their individual ventilatory threshold. Plasma concentrations of ET-1 in both sides of femoral veins (veins in the working leg and nonworking leg) and in the femoral artery (artery in the nonworking leg) were measured before and after exercise. The plasma ET-1 concentration in the femoral vein in the nonworking leg was significantly increased after exercise, whereas that in femoral vein in the working leg was not changed. The arteriovenous difference in ET-1 concentration was significantly increased after exercise in the circulation of the nonworking leg but not of the working leg, which suggests that the production of ET-1 was increased in the circulation of the nonworking leg by exercise. The present study also demonstrated that the plasma norepinephrine concentrations were elevated by exercise in the femoral veins of both the working and nonworking legs, suggesting that the sympathetic nerve activity was augmented in both legs during exercise. Therefore, the present study demonstrates the possibility that the increase in production of ET-1 in nonworking muscles may cause vasoconstriction and hence decrease blood flow in nonworking muscles through its direct vasoconstrictive action or through an indirect effect of ET-1 to enhance vasoconstrictions to norepinephrine and that these responses may be helpful in increasing blood flow in working muscles. We propose that endogenous ET-1 contributes to the exercise-induced redistribution of blood flow in muscles.

Adolescent↗
PubMed1997

Possible different mechanism between amyloid-beta (25-35)-and substance P-induced chemotaxis of murine microglia.

The mechanism of murine microglial chemotaxis induced by amyloid-beta protein (A beta (25-35)) was investigated. A beta (25-35) dose-dependently stimulated microglial chemotaxis at concentrations between 100 pM and 10 nM. Substance P, a NK-1 agonist, stimulated chemotaxis at concentrations of 10 nM or more. GR-64349, a NK-2 agonist, and senktide, a NK-3 agonist, did not stimulate microglial chemotaxis. We examined whether homologous desensitization of chemotaxis would occur by A beta (25-35). The chemotactic effect of microglia was homologously desensitized by 10 nM A beta (25-35). On the other hand, substance P at 10 nM did not desensitize the A beta (25-35)-induced chemotaxis. These data show that A beta (25-35) induces the chemotaxis of microglia probably through a receptor other than the NK-1 receptor.

Amyloid beta-Peptides↗
PubMed1997

Leiomyoma of the scrotum.

Leiomyoma is a benign tumor derived from smooth muscle. Leiomyoma of the scrotum arising from the tunica dartos is exceedingly rare. We describe the case of a 51-year-old Japanese man with this disease entity.

Cell Nucleus↗
PubMed1997

Inhibition by nitric oxide of the uptake of [3H]serotonin into rat brain synaptosomes.

[3H]Serotonin (5-HT) uptake by synaptosomes of rat brain was dose-dependently inhibited by nitric oxide (NO) donors such as sodium nitroprusside (SNP), 3-(2-hydroxy-1-methyl-2-nitrosohydrazino)-N-methyl-1-propanamin e, 3-morpholinosydnonimine and S-nitroso-L-cysteine (NO-CYS). The inhibitory effect was blocked by reduced hemoglobin. The effect was not mimicked by ferrocyanide and ferricyanide. 8-Bromoguanosine 3',5'-cyclic monophosphate (8-bromo cGMP) did not affect [3H]5-HT uptake into rat cortical synaptosomes. The reduced activity of [3H]5-HT uptake into the cortical synaptosomes pretreated with NO-CYS was partially reversed by washing the preparation after the treatment. Kinetic analysis showed that NO-CYS (100 microM) decreased the Vmax value without any change in the Km value. NO-CYS did not affect the specific binding of [3H]paroxetine, a ligand that binds to the 5-HT transporter, in membranes. NO-CYS and SNP, like iodoacetic acid and sodium cyanide, decreased the ATP content in cortical synaptosomes, but the effect on ATP content was not related to that on [3H]5-HT uptake. These findings suggest that NO inhibits reversibly [3H]5-HT uptake into rat brain synaptosomes without affecting the recognition site of the 5-HT transporter in a cGMP-independent manner, and the observed effect is not due to its metabolic effect.

Adenosine Triphosphate↗
PubMed1997

Long-term culture of primary rat hepatocytes on heparin- or lambda carrageenan-containing collagen gels.

The interactions of glycosaminoglycans (GAGs) with collagen are thought to be important in cell adhesion and cell differentiation. To investigate whether the interactions of GAG or sulfated polysaccharide with collagen can maintain the functions of cultured primary rat hepatocytes, GAG- or sulfated polysaccharide-containing collagen gels were reconstituted in vitro and used for culture of hepatocytes. Among the GAGs and sulfated polysaccharides examined, heparin- and lambda carrageenan-containing collagen gels were found to be able to stimulate and sustain albumin synthesis, while the other GAG- or sulfated polysaccharide-containing collagen gels had almost no effect on maintenance of albumin synthesis. In the cultures using collagen gels that contained 400 micrograms/ml heparin or 100 micrograms/ml lambda carrageenan, albumin synthesis by rat hepatocytes was prolonged to about 4 and 5 weeks, respectively, but albumin synthesis was kept up for only one week in the cultures using conventional collagen gels. These results suggest that the interactions of heparin or lambda carrageenan might be of importance for long-term maintenance of hepatocyte functions.

Albumins↗
PubMed1997

Expression pattern of the mitochondrial capsule selenoprotein mRNA in the mouse testis after puberty; in situ hybridization study.

Mitochondrial capsule selenoprotein (MCS) has been known as a structural protein of the mitochondrial sheath in spermatozoa. In this study, to determine the expression pattern of MCS mRNA in the mouse testis after puberty, in situ hybridization using digoxigenin-labeled RNA probes for MCS was performed in the testes of 8- and 20-week-old ICR mice. In the testes of both ages, MCS mRNA first appeared in step 3 round spermatids, gradually increased during early spermiogenesis, and persisted a high level until step 14 spermatids. After the step 14 spermatids, the signal began to decline and was weakly detected in steps 15-16 spermatids. On the other hand, compared with that in the testes of 8-week-old mice, MCS mRNA level in the testes of 20-week-old mice increased over 2-fold at stages VI-III, while it slightly increased at stages IV-V. These findings suggest that MCS gene transcription may be up-regulated after puberty in the mouse testis.

Aging↗
PubMed1997

Analysis of osteocalcin expression in transgenic mice reveals a species difference in vitamin D regulation of mouse and human osteocalcin genes.

A line of transgenic mice expressing a human osteocalcin genomic fragment (hOClocus) and a murine MC3T3-E1 cell line containing a stably integrated human osteocalcin promoter construct have been developed to characterize the osteogenic and hormonal regulation of human osteocalcin in vivo and in vitro. In this study, we used these models to demonstrate a species difference in the regulation of the mouse and human osteocalcin genes by vitamin D. Repeated administration of 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) to mice carrying the hOClocus transgene resulted in striking increases in serum human osteocalcin, whereas serum mouse osteocalcin levels were unchanged after 24 h and only modestly increased 48 h after the second dose of hormone. 1,25(OH)2D3 increased human calvarial mRNA expression by 1.8-fold and slightly decreased mouse osteocalcin mRNA levels by approximately 1.2-fold. Furthermore, treatment of primary calvarial osteoblasts from these mice with 1,25(OH)2D3 increased human osteocalcin production but inhibited mouse osteocalcin protein accumulation. To investigate further the mechanism for the apparent species difference in vitamin D3 induction of mouse and human osteocalcin, we examined the effect of 1,25(OH)2D3 in an MC3T3-E1 cell line (MC4) containing a stably integrated 3900 bp osteocalcin promoter-luciferase construct. Treatment of MC4 cells with ascorbic acid resulted in parallel increases of the endogenous mouse osteocalcin protein and luciferase reporter activity over a 12-day period. Continuous exposure of MC4 cells to 1,25(OH)2D3 resulted in time-and dose-dependent increases in the activity of the phOC3900 luciferase construct. By contrast, the hormone had no effect on mouse osteocalcin protein concentrations and inhibited its induction by ascorbic acid. However, when cells were treated acutely with 1,25(OH)2D3 at later times during growth in ascorbic acid, the induction of mouse osteocalcin protein was only partially inhibited. In conclusion, our results indicate that common osteogenic signals regulate both mouse and human osteocalcin gene expression, but the mouse gene is resistant to induction by vitamin D. This species difference in vitamin D regulation of osteocalcin appears to result from the failure of 1,25(OH)2D3 to transcriptionally activate the mouse osteocalcin gene.

3T3 Cells↗
PubMed1997

Combination chemotherapy for malignant paraganglioma.

Treatment with a combination chemotherapeutic regimen consisting of cyclophosphamide, vincristine, and dacarbazine for malignant paraganglioma with hepatic metastasis is reported. A 51-year-old male presented with tumors in the retroperitoneal space and liver. The patient was diagnosed as having paraganglioma based on elevated levels of serum neuron-specific enolase, urinary catecholamine and vanillylmandelic acid, and on histological findings of the liver specimen. The patient was treated with this combination chemotherapy in repeated 21-day cycles. Temporary improvement in laboratory findings and a 20% reduction in the size of the hepatic masses were observed without severe adverse effects.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1997

A comparison of vibrotactile thresholds on the finger obtained with ISO type equipment and Japanese equipment.

A vibrotactile threshold measurement system that enables the thresholds at the fingertips to be determined more rapidly and precisely has been developed. This system was studied to assess the impact of various factors on the obtained values. An experiment using two different types of equipment was also conducted to assess the repeatability of measurement. One system was similar to that required by International Standard (System A), and the other system was of the currently used in Japan (System B). The subjects were nine males and one female, measurements were taken on three different days. This paper compares the structure of the equipment used internationally (ISO/CD13091) and the equipment typically used in Japan and the measurements of vibrotactile thresholds taken at a 125 Hz frequency using Systems A and B. The measurement method and conditions adopted were almost the same as those outlined in the ISO draft. The results of this experiment showed that there were some differences between the two systems. The vibrotactile thresholds measured using System B showed higher values than did those measured using System A. The results also indicated that equipment that satisfies ISO standards provides sufficient repeatability for use as a diagnostic aid. Also, this paper is shown the vibrotactile measurement equipment conditions must be considered when using vibrotactile threshold measurement equipment in Japan.

Durable Medical Equipment↗
PubMed1997

An infrasound experiment system for industrial hygiene.

An infrasound experiment system has been constructed in order to investigate the effects of infrasound on human health from the point of view of industrial hygiene and to establish a method to assess it in working environments. Some measurements were carried out to evaluate the acoustic performance of the system in the low frequency sound range, including infrasound, and to clarify the points to be improved. As a result, it was found that the system had some weak points in the audible frequency range. They were considered to be caused by the large capacity of the test chamber, and some countermeasures were required. On the other hand, in the infrasound range, it appeared that the higher harmonics of infrasound possibly affected the experiments and some limitations might be found necessary. But the frequency response of the chamber and the spatial uniformity of the reproduced infrasound proved to be satisfactory for the experiments in this range. Consequently it was concluded that the system could contribute to the study of infrasound.

Acoustics↗
PubMed1997

Roxithromycin attenuates acid-induced cough and water-induced bronchoconstriction in children with asthma.

In the present study, we evaluated the effect of roxithromycin, a semisynthetic macrolide antibiotic, on the cough response to inhaled acetic acid (AA) and on the bronchoconstriction induced by ultrasonically nebulized distilled water (UNDW) in children with asthma. Ten hospitalized asthmatic children (8 boys and 2 girls, mean +/- SEM age 12.6 +/- 0.4 years) were enrolled in this study. They were treated with 150 mg of roxithromycin once a day orally for 8 weeks without any side effects. All the patients underwent AA inhalation challenge before and 2, 4, and 8 weeks after the administration of roxithromycin. Seven of the 10 patients, who had a fall in FEV1 of at least 20% after UNDW inhalation, underwent UNDW inhalation challege at the same time. The cough threshold values, the lowest concentrations of AA eliciting coughs, and UNDW provocative dose producing a 20% fall in FEV1 (UNDW PD20) values 4 or 8 weeks after the administration of roxithromycin increased significantly over the initial values (p < 0.05). No significant change was observed in baseline FEV1 or serum theophylline concentrations throughout the study. These results support the notion that administration of roxithromycin may have favorable results in the treatment of childhood asthma.

Acetic Acid↗
PubMed1997

Analysis of amyloid deposition in a transgenic mouse model of homozygous familial amyloidotic polyneuropathy.

Amyloid fibrils derived from the Japanese, Portuguese, and Swedish types of familial amyloidotic polyneuropathy all consist of a variant transthyretin (TTR) with a substitution of methionine for valine at position 30 (TTR Met 30). In an attempt to establish an animal model of TTR Met-30-associated homozygous familial amyloidotic polyneuropathy and to study the structural and functional properties of human TTR Met 30, we generated a mouse line carrying a null mutation at the endogenous ttr locus (ttr-/-) and the human mutant ttr gene (6.0-hMet 30) as a transgene. In these mice, human TTR Met-30-derived amyloid deposits were first observed in the esophagus and stomach when the mice were 11 months of age. With advancing age, amyloid deposits extended to various other tissues. Because no significant difference was detected in the onset, progression, and tissue distribution of amyloid deposition between the ttr-/- and ttr+/+ transgenic mice expressing 6.0-hMet 30, endogenous normal mouse TTR probably does not affect the deposition of human TTR Met-30-derived amyloid in mice. TTR is a tetramer composed of four identical subunits that binds thyroxine (T4) and plasma retinol-binding protein. The introduction of 6.0-hMet 30 into the ttr-/- mice significantly increased their depressed serum levels of T4 and retinol-binding protein, suggesting that human TTR Met 30 binds T4 and retinol-binding protein in vivo. The T4-binding ability of human TTR Met 30 was confirmed by the analysis of T4-binding proteins in the sera of ttr-/- transgenic mice expressing 6.0-hMet 30. The T4-binding studies also demonstrated the presence of hybrid tetramers between mouse and human TTR subunits in the ttr+/+ transgenic mice expressing 6.0-hMet 30.

Amyloid↗
PubMed1997

[Effect of thoracoscopic procedure versus standard posterolateral/muscle-sparing thoracotomy on pulmonary lung function].

To understand the effects of thoracoscopic approach to thoracotomy on lung function, we investigated the changes in lung function after thoracoscopic operation (n = 7) and compared them to those after standard posterolateral (n = 5) or muscle-sparing thoracotomy (n = 6). In 18 patients with benign lung tumor in which surgical treatment resected in partial resection of the lung tissue, we measured TLC, VC, RV, FEV1.0, FEV1.0%, Peak Flow and DLco preoperatively and at 2, 4 weeks postoperatively. In the standard posterolateral or muscle-sparing thoracotomy groups, FVC, TLC, FEV1.0 and Peak Flow decreased to about 80% of preoperative value at 2 weeks. At 4 weeks after operation, these values showed to increase some what, but did not reach to the preoperative value. Whereas, the thoracoscopic procedure group, did not show the decrease in lung function through the time course. There was not significant different between standard posterolateral and muscle-sparing thoracotomy. We conclude that thoracoscopic approach is an useful technique to thoracotomy because of its minimizing after thoracotomy effect of lung function loss.

Adult↗
PubMed1997

[A case of concurrent bilateral adrenocortical adenoma causing Cushing's syndrome].

A 43-year-old woman presented with obesity and lumbago. Endocrinological examinations revealed normal plasma cortisol levels and a suppressed serum adrenocorticotropic hormone (ACTH) level. On venous sampling, markedly elevated plasma cortisol levels were observed for bilateral adrenal veins (243 and 62.3 micrograms/dl on the right and left sides, respectively). Although the computed tomogram revealed bilaterally enlarged adrenal glands, 131I-adosterol scintigram showed a strong uptake only on the right side. Right adrenalectomy successfully relieved Cushing's syndrome. Pathological diagnosis was adrenocortical adenoma, 3.5 cm in diameter. Cushing's syndrome recurred in 9 years. At that time, she underwent left subtotal adrenalectomy including a 3-cm adrenocortical adenoma. Postoperative convalescence has been uneventful with oral steroid supplementation. All 14 previously reported cases of bilateral adrenocortical adenoma (BAA) causing Cushing's syndrome as well as the present case were concurrent and dominant in females of reproductive age. This suggests that some cofactors other than ACTH, such as estrogen, contribute to the pathogenesis of BAA.

Adenoma↗
PubMed1997

Influence of chemotherapy on FDG uptake by human cancer xenografts in nude mice.

UNLABELLED: This study evaluated the use of PET with 18F-2-deoxy-2-fluoro-D-glucose (18F-FDG) for monitoring chemotherapy effects, using a human cancer xenograft (poorly differentiated human gastric cancer) in vivo model. METHODS: Tumor 18F-FDG uptakes and sizes were measured after administrating mitomycin (MMC), cisplatin (CDDP) and adriamycin (ADR) to xenograft-bearing nude mice and compared with 18F-FDG tumor uptake and tumor size in a non-therapy group. The correlation between the uptake and size was also assessed. RESULTS: The largest reduction in tumor size after chemotherapy occurred in the MMC administered group, followed by the CDDP case, with no reduction in the ADR group as compared to the controls. Fluorine-18-FDG tumor uptake after chemotherapy was also decreased in the MMC and CDDP groups, in that order, but not in the ADR case. With MMC and CDDP, size reduction became significant on Days 8 or 11, whereas 18F-FDG tumor uptake had already been decreased on Days 3 or 7. CONCLUSION: Fluorine-18-FDG uptake decreases in parallel to the efficacy of anticancer agents and correlates with subsequent morphologic changes. We conclude that 18F-FDG PET tumor images are indeed useful for monitoring the effects of cancer chemotherapy.

Adenocarcinoma↗
PubMed1997

[A case of mediastinal tuberculous lymphadenitis with tracheal stenosis].

68-year-old female was introduced our hospital for productive cough and dyspnea. Chest X ray film showed right upper mediastinal mass and tracheal stenosis. Chest CT showed mediastinal mass with calcifying lesion. ESR at 1 hour was 50 mm and CRP was 1.08 micrograms/ml. Because of progressive dyspnea, the operation was performed without further assessment. We found a mass of adhesive lymph nodes by the side of trachea. We removed it and it turned out to be tuberculous lymphadenitis. Postoperative PPD skin test showed strongly positive reaction. She has taken medication by antituberculous drugs and lives well without complications.

Antitubercular Agents↗
PubMed1997

Role of alternative splicing of the rat erythropoietin receptor gene in normal and erythroleukemia cells.

An alternatively splicing of the rat erythropoietin receptor (EpoR) gene was identified in normal and erythroleukemia cells by the reverse transcription PCR method. Insertion of a 105 bp fragment at the region corresponding to the extracellular domain of rat EpoR was found. The insert sequence, which encodes additional 21 amino acids, is similar to that previously found in the mouse EpoR gene, however, has an additional 27 bp direct repeat. Due to the presence of a stop codon in the insert, the alternative transcript is translated to a truncated and soluble form of EpoR which is preferentially expressed in liver, spleen, kidney, heart, and bone marrow cells as well as cultured erythroleukemia cells. These findings suggest that alternative splicing of the EpoR gene may play an important role in proliferation and differentiation of rat erythroid cells.

Alternative Splicing↗