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Biomedical subjects

M Tokiwa

Publications and source records attributed to M Tokiwa.

13 recordsLinked to original sources
PubMed2003

Strong static magnetic field and the induction of mutations through elevated production of reactive oxygen species in Escherichia coli soxR.

PURPOSE: Although strong static magnetic fields (SMF) are supposed to have the potential to affect biological systems, the effects have not been evaluated sufficiently. Experiments should be performed with a powerful SMF-generating apparatus to evaluate the biological effects of SMF. MATERIALS AND METHODS: An Escherichia coli mutation assay was used to assess the mutagenic effects of strong SMF. Various mutant strains of E. coli were exposed to up to 9 Tesla (T) for 24 h and the frequencies of rifampicin-resistant mutations were then determined. The expression of the soxS::lacZ fusion gene was assessed by measurement of beta-galactosidase activity. RESULTS: The results for survival or mutation were obtained with wild-type E. coli strain GC4468 and its derivatives defective in DNA repair enzymes or redox-regulating enzymes were all negative. On the other hand, the mutation frequency was significantly increased by the SMF exposure in soxR and sodAsodB mutants, which are defective in defence mechanisms against oxidative stress. Furthermore, the expression of superoxide-inducible soxS::lacZ fusion gene was stimulated 1.4- and 1.8-fold in E. coli when exposed to 5 and 9 T, respectively. CONCLUSIONS: These results indicate that strong SMF induce mutations through elevated production of intracellular superoxide radicals in E. coli.

Bacterial Proteins↗
PubMed2000

Effects of FTY720, a novel immunosuppressant, on experimental autoimmune uveoretinitis in rats.

The immunosuppressive properties of FTY720, a novel immunosuppressant obtained by structural modification of ISP-I isolated from the fermentation broth of Isaria sinclairii, were studied in experimental autoimmune uveoretinitis (EAU) in rats. Lewis rats were immunized with S-antigen and treated with FTY720 (0. 03, 0.06, 0.1 mg kg(-1)day(-1)) or distilled water for 16 days after the immunization. FTY720 suppressed the incidence and intensity of EAU in a dose-dependent manner as demonstrated by clinical and histological examinations. The drug significantly suppressed the serum levels of antibodies to S-antigen and antigens-specific lymphocyte proliferation. The number of peripheral lymphocytes, but not neutrophils, was markedly reduced by FTY720 treatment. FTY720 also suppressed the intensity of EAU when it was given from the day of EAU onset. These results indicate that FTY720 has intense immunosuppressive effects on EAU in rats and may be a potential candidate for use in the treatment of patients with autoimmune uveitis.

Animals↗
PubMed1999

[Spontaneous rupture of renal cell carcinoma: a case report].

A 74-year-old man with severe right flank pain and hypochondralgia, was admitted to a hospital where he was found to have an abnormality of the right kidney on computed tomographic (CT) scan. He was referred to our department for further examination and treatment on the next day. Spontaneous rupture of the right renal cell carcinoma was mostly suspected from preoperative clinical findings obtained by ultrasonography. CT scan and angiography. Extravasation was not recognized on angiography. We chose emergent transcatheter arterial embolization prior to radical nephrectomy. The surgical specimen contained a solid and yellowish mass invading into the renal pelvis. Subcapsular rupture was identified. Histopathological diagnosis was renal cell carcinoma consisting of invasive growth of highly atypical epithelial cells with a sarcomatous pattern, and the tumor cells were present in the renal pelvis. He died of lung cancer 26 months after the operation.

Aged↗
PubMed1998

Relationship between serum ELAM-1 and metastasis among patients with colon cancer.

PURPOSE: We studied serum ELAM-1 levels in colon cancer patients. METHODS AND RESULTS: Serum ELAM-1 levels were significantly higher in 52 patients with colon cancer (mean +/- standard deviation, 69.3 +/- 28.6 U/ml) compared with 32 healthy volunteers (36.5 +/- 11.9 U/ml; P < 0.001). The mean serum ELAM-1 level in patients with metastatic tumors was significantly greater than that of patients with nonmetastatic tumors. Sensitivity and specificity of serum ELAM-1 elevation in detecting metastasis was 75 and 87.5 percent, respectively. Those of carcinoembryonic antigen and carbohydrate antigen 19-9 elevations were 71.4 and 62.5 percent and 35.7 and 91.7 percent, respectively. Twenty-five (89.3 percent) of 28 metastatic tumors showed either serum ELAM-1 or carcinoembryonic antigen elevation. There were weak but significant correlations found between serum ELAM-1 and carcinoembryonic antigen or carbohydrate antigen 19-9 levels. Moreover, serum ELAM-1 increased before detecting the recurrence by imaging in five of seven recurrent colon cancer patients. CONCLUSION: These findings suggest that serum ELAM-1 could be a useful tumor marker for colon cancer, especially in synchronous and metaclonous metastasis.

Adult↗
PubMed1995

[The effects of fitness-type exercise on iron status and hematological status for female college students].

Forty-two female college students underwent fitness-type exercise over a 13 week period. The students exercised an average of two times a week for 30 minute periods at 50% levels of VO2 . max. Iron status and hematological laboratory data were monitored at three points in time; at the initiation of exercise, at the termination of exercise and 3 months later. Serum ferritin levels in a third of the students were lower than 12ng/ml. Red blood cell counts decreased during exercise, and returned to the pre-exercise levels 3 months later. The number of circulatory reticulocytes and mean corpuscular hemoglobin concentration were increased significantly after the exercise and the effects were still observed 3 months later, independent of the iron status. In the lower ferritin group, erythropoietin levels decreased significantly during the post-exercise period. The average serum ferritin levels while showing no significant changes during exercise, increased significantly during the post-exercise period, in the normal ferritin group. We discussed possible mechanisms, among them iron metabolism, by which physical training may facilitate erythropoiesis. However, no definite conclusions have been reached.

Adult↗
PubMed1989

Intracavernous injection of prostaglandin E1 for the treatment of erectile impotence.

We administered intracavernous injections of 20 micrograms. prostaglandin E1 to 135 patients with impotence, and evaluated the effects and side effects. Among 135 patients who underwent intracavernous injection of prostaglandin E1 complete erection was observed in 83 (62 per cent), while incomplete erection was noted in 33 (24 per cent). In both groups the erection was sufficient for sexual intercourse. Tumescence without rigidity was noted in 12 patients and no response was obtained in 7. Poor response was seen frequently in patients with disorders of the vascular system and/or damage to the cavernous body of the penis. Priapism after the injection was not observed. Moreover, we never observed any other severe side effects. Intracavernous injection of prostaglandin E1 could be applicable to the therapy of impotence, especially that due to neurogenic disturbance. Since prostaglandin E1 acts quickly and loses its validity rapidly it is considered to be a more suitable agent than other vasoactive drugs.

Adult↗