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Biomedical subjects

M Usuda

Publications and source records attributed to M Usuda.

At least 19 recordsLinked to original sources
PubMed1994

Aberrant CYP1A1 induction: discrepancy of CYP1A1 mRNA and aryl hydrocarbon hydroxylase activity in mutant cells of mouse hepatoma line, Hepa-1.

We have isolated new benzo[a]pyrene-resistant clones, cl-21 and cl-32, of the mouse hepatoma line, Hepa-1. CYP1A1-dependent aryl hydrocarbon hydroxylase activity is not inducible by 2,3,7,8-tetrachlorodibenzo-p-dioxin or 3-methylcholanthrene in these two cell lines. However, mRNA of CYP1A1 is inducible in cl-21 and cl-32 cells, as in the wild-type cells, in spite of an undetectable level of cytosolic Ah receptor. The cl-21 cDNA of Cyp1a-1 was found to have a single mutation leading to an amino acid substitution from Leu (118) to Arg (118). However, the CYP1A1 protein band was not detected on Western immunoblots. The cDNA of cl-32 was found to have a single mutation leading to an amino acid change from Arg (359) to Trp (359). The presence of the mature protein in cl-32 was confirmed by Western blot analysis. Somatic cell hybridization experiments demonstrated that the phenotype of cl-21 and cl-32 is recessive and that these clones belong to the same complementation group. These data suggest that there may be a non-Ah receptor-mediated mechanism of CYP1A1 induction.

Animals↗
PubMed1994

[Changes in liver tissue amino acids during hemorrhagic shock].

Changes in amino acids in liver tissue during hemorrhagic shock were examined in eight mature mongrel dogs using the microdialysis method. The mean blood pressure was maintained at 50 mmHg by exsanguination, and the values of liver tissue amino acids after 30 minutes showed significant decreases of aspartate, glutamate, histidine, glutamine, glycine and taurine. The decrease of taurine was especially marked. The values dropped further 30 minutes after returning the blood into circulation with some exceptions. These results suggest the possibility that hemorrhagic shock causes reduction in uptake of amino acids by the liver or consumption of amino acids in the liver, and that bile acid metabolism appears to be disturbed by the marked drop in the taurine level. It is necessary to give careful consideration to the possible existence of reduced amino acid metabolism in the liver in the treatment of hemorrhagic shock.

Amino Acids↗
PubMed1992

Application of the chemiluminescent assay to cytotoxicity test: detection of menadione-catalyzed H2O2 production by viable cells.

Menadione-catalyzed H2O2 production by viable cells is proportional to viable cell number. The correlations between the viable cell number and the concentration of H2O2 produced are determined with the rapid chemiluminescent assay (S. Yamashoji, T. Ikeda, and K. Yamashoji, 1989, Anal. Biochem. 181, 149-152). This chemiluminescent assay of viable cells requires only 10 min and is much faster than NR (neutral red) inclusion and MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) reduction assays, which require 3-5 h. When viable cells are incubated with antitumor drugs, detergents, mycotoxins, and glycoalkaloids for 24-48 h, a decrease in menadione-catalyzed H2O2 production in a dose- or incubation time-dependent manner is observed. In general, the 50% inhibition concentration determined by the chemiluminescent assay is lower than that determined by NR inclusion and MTT reduction assays, and the order of relative cytotoxic effects of agents is the same among these assays. Furthermore, clear cytotoxic effects are observed by the chemiluminescent assay after 1 h exposure of trypsinized cells to toxic compounds. Therefore, the chemiluminescent assay is expected to be more useful for the rapid detection of cytotoxic compounds than NR inclusion and MTT reduction assays.

3T3 Cells↗
PubMed1992

[Cardiovascular effects of, and catecholamine response to, high dose fentanyl or NLA in patients for valve replacement].

We measured the cardiovascular effect of, and catecholamine and other hormonal responses to, anesthetic doses of fentanyl and original NLA in 25 patients for open heart surgery. The patients were randomly divided into three groups (group N, F30, F75). During induction, in group N; droperidol 0.25 mg.kg-1 and fentanyl 5 micrograms.kg-1, in group F30; fentanyl 30 micrograms.kg-1, and in group F75; fentanyl 75 micrograms.kg-1 were administered intravenously. Additional fentanyl was administered at a rate of 100 to 200 micrograms.h-1. Droperidol 0.25 mg.kg-1 was administered in group N when cardiopulmonary bypass (CPB) was disconnected. Plasma samples were assayed for norepinephrine, epinephrine, ACTH and cortisol before and after induction, during sternotomy, 60 minutes after institution of CPB, after weaning from CPB, and before as well as after extubation. Heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP) and rate pressure product (RPP) were calculated simultaneously at the blood samplings. In all groups, no remarkable change in cardiovascular dynamics was observed. CPB was associated with marked increases in catecholamines, but high dose fentanyl in dose of 75 micrograms.kg-1 was able to suppress epinephrine level more than in group N. In high dose fentanyl group (F30, F75) ACTH was within normal ranges, even during CPB. The results suggest that high dose fentanyl is a complete anesthetic in patients for cardiac surgery. But a large dose of fentanyl causes small decreases in heart rate and arterial blood pressure. Our data indicate that group F30 is an attractive anesthetic technique for patients with valvular disease.

Adrenocorticotropic Hormone↗
PubMed1990

[Removal of small molecular proteins by push/pull HDF and alleviation of shoulder joint pain].

The purpose of the present study was to compare hemodialysis (HD) and push/pull HDF in terms of uremic substance removal and clinical improvement. The treatment of patients complaining of shoulder joint pain was changed from conventional HD to HD or push/pull HDF using a hemodiafilter with large membrane pores. Push/pull HDF showed significantly greater removal of beta 2-microglobulin (beta 2-m) and other small molecular proteins than HD, and serum beta 2-m was significantly lower in concentration with push/pull HDF than HD. There was a decrease in the shoulder joint pain from push/pull HDF, and the range of upper arm movement thereby increased. However, neither this decrease in pain nor the increase in upper arm movement resulted with HD treatment. Hence, it was concluded that push/pull HDF is a more effective form of therapy.

Adult↗
PubMed1986

Newly developed circulating blood volume-monitoring system and its clinical application for measuring changes in blood volume during hemofiltration.

Blood and ultrafiltrate electrical resistivities were continuously monitored during hemofiltration. By substituting these values into a previously developed equation that was modified by the authors, the hematocrit value was determined; and blood volume change was obtained from the change in this value. The following facts were discovered as the result of monitoring the blood volume change during treatment: When the body position was changed from the reclining to the sitting position, the blood volume decreased by 4.2 +/- 0.3%. With the body water removal rate kept constant, the body position recumbent, and the subject fasted, the blood volume gradually decreased. However, when the position was changed from reclining to sitting for food intake and once more returned to the supine position after the meal, the blood volume was greatly affected by the change in position and the food intake.

Blood↗
PubMed1983

Plasma exchange for treatment of intractable psoriasis.

Hemofiltration and plasma exchange, using a plasma separator with membranes, were used in 14 psoriatic patients. The efficacies of the treatments were compared. Among the patients, 13 were treated with hemofiltration and/or direct hemoperfusion, 5 experienced complete remission, 5 improved, and 3 remained unaffected. In these 3 cases, plasma exchange was performed. The first patient, who suffered from psoriasis pustulosa with arthropathica, achieved complete remission with only two treatment of 2-L plasma exchange. Joint pain was also eliminated. Both skin lesions and joint pain were markedly improved in the second patient, who suffered from psoriasis vulgaris with arthropathica. The third patient showed marked improvement with only two plasma exchanges, and is under continuing observation.

Adult↗
PubMed1982

Infusion-free hemodiafiltration: simultaneous hemofiltration and dialysis with no need for infusion fluid.

A new simultaneous hemofiltration and dialysis system was developed which has no need of infusion fluid. The system employs two hemodiafilters in a direct series. An ultrafiltration rate and dialysate flow rate control system was employed to control the dialysate flow at the inlet and outlet, and the difference in volume was arranged to be the amount of water removed from the body. When the blood circuit was narrowed between the two hemodiafilters, the ultrafiltration was performed at the first hemodiafilter; at the second one, the dialysate moved to the blood side as a dilution fluid. To remove pyrogens and bacteria, tap water was subjected to activated charcoal, ion exchange and reverse osmosis treatment, followed by preparation of the dialysate. In clinical evaluation, this system showed marked improvement in clearance of middle and large molecules.

Adult↗
PubMed1980

Effects of ticlopidine on thrombotic obstruction of A-V shunts and on dialysance of artificial kidneys.

Administration of ticlopidine, a new inhibitor of platelet aggregation, during hemodialysis to two patients with thrombotic occlusion of external A-V shunts markedly suppressed the obstruction of the shunt and improved anemia. Consequently, it was concluded that this drug may be useful for maintaining good blood flow and good patency of shunts in patients undergoing dialysis. In order to determine the dialyzer efficiency during dialysis, the reduction rate of the dialyzer was determined in vitro. The dialyzer reduction rates for urea, creatinine, uric acid, and phosphoric acid were all lowered after dialysis, and the administration of ticlopidine resulted in a suppression of the drop in the reduction rate. Based on the inhibitory effect of ticlopidine on platelet aggregation, it was assumed that a close correlation may exist between adhesion and aggregation of platelets and the drop in the efficiency of the dialyzer during dialysis as well as thrombotic obstruction of shunts.

Adult↗
PubMed1978

Histological observations on some of the endocrine glands in the ironfish, with special regard to the hypophysis.

Endocrine glands of the ironfish were studied light microscopically to elucidate the relationship between the races of the genus Carassius. The rostral pars distalis of the adenohypophysis consists mainly of acidophils corresponding to prolactin cells and lead-hematoxylin positive cells corresponding to corticotrophs (ACTH cells). The prolactin cells are obviously arranged in the form of follicles. The proximal pars distalis contains orangenophils (STH cells) and two types of basophils (TSH and GTH cells). In the pars intermedia, three types of cells are identified: periodic acid Schiff positive cells, lead-hematoxylin stainable cells and orangenophils containing PAS positive coarse granules. In addition, small agranular cells are seldom demonstrated in the entire adenohypophysis. A considerable amount of aldehyde fuchsin positive neurosecretory material is laden in the cells of the nucleus preopticus and in the pars nervosa. The nucleus lateralis tuberis is composed of three portions: pars anterior, pars posterior, and pars lateralis. The thyroid follicles found in the pharyngeal region and head kidney show a mild state of activity. The interrenal cells intermingled with the chromaffin cells have a considerable amount of eosinophil cytoplasm. Judging from the gonadal condition, the breeding season of the ironfish may extend to the end of July.

Animals↗