Significance of uric acid clearance in preeclampsia.
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Female↗
Biomedical subjects
A Yoshimura
Publications and source records attributed to A Yoshimura.
Effects of ions and drugs on the responses of sensory axon terminals of decapsulated frog muscle spindles.
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Animals↗
Friend spleen focus-forming virus glycoprotein gp55 interacts with the erythropoietin receptor in the endoplasmic reticulum and affects receptor metabolism.
The Friend spleen focus-forming virus envelope glycoprotein, gp55, binds to the murine erythropoietin receptor (EPO-R) and triggers growth activation in the absence of EPO. Interleukin 3-dependent lymphoid cell lines that have been stably transfected with the EPO-R cDNA grow in the presence of EPO or interleukin 3. In these cells, the EPO-R is synthesized as a minor 62-kDa unglycosylated form and a major 64-kDa form carrying one high-mannose N-linked oligosaccharide. A fraction of the 64-kDa form is processed to a 66-kDa species with complex-type sugars. Very little of the EPO-R is expressed on the cell surface and all three forms of EPO-R are degraded rapidly. Cells transfected with both EPO-R and gp55 cDNAs grow in the absence of EPO. Most of the EPO-R associated with gp55 is endoglycosidase H-sensitive, suggesting that the interactions between these proteins occur in the endoplasmic reticulum. Furthermore, the endoglycosidase H-sensitive EPO-R is more stable than in the absence of gp55, a result suggesting that interaction of gp55 with the EPO-R causes it to remain within the rough endoplasmic reticulum. It is possible that gp55 EPO-R complexes within this compartment send a growth-promoting signal to the cell.
Animals↗
Expression of the multidrug transporter, P-glycoprotein, in chronic myelogenous leukaemia cells in blast crisis.
The overexpression of a cell-surface glycoprotein termed P-glycoprotein (P-gp) is frequently associated with multidrug resistance (MDR) in cell lines in vitro. To evaluate the implications of P-gp expression in clinical drug-resistance, we examined the expression of P-gp in fresh leukaemia cells from chronic myelogenous leukaemia (CML) patients in blast crisis. By using immunoblotting with a monoclonal antibody against P-gp, C219, we showed that leukaemia cells from three CML patients in blast crisis were P-gp negative at the stage when these patients were in complete remission, and that the cells showed high levels of P-gp expression at times when the same patients had relapsed and had not responded to chemotherapy. Six out of 11 patients (nine in the refractory state) were P-gp positive and they rarely responded to chemotherapy. These data suggest that the expression of P-gp is closely associated with drug-resistance in CML.
ATP Binding Cassette Transporter, Subfamily B, Mem↗
Chloranil-photosensitized monomerization of dimethylthymine cyclobutane dimers and effect of magnesium perchlorate.
The photosensitized monomerization of the cyclobutane dimers of 1,3-dimethylthymine by p-chloranil was investigated by means of steady-state irradiation and laser-flash photolysis. Quantum yields for the monomerization are 0.34 for the cis,syn dimer, 0.39 for the trans,syn dimer, and much less than 10(-2) for the cis,anti isomer. Formation of the chloranil anion radical associated with quenching of triplet chloranil by the dimers demonstrates that electron transfer from dimers to triplet chloranil occurs to initiate the monomerization. Kinetic analysis suggested that the syn-dimer cation radicals undergo the ring cleavage at greater than or equal to 10(9) s-1 before escaping from the solvent cage, while the reactivity of the anti-dimer cation radical is very low. The different reactivities of the syn and anti dimer cation radicals are discussed in terms of through-bond coupling between the n orbitals of N(1) and N(1') involving the cyclobutane-ring sigma orbitals. In the cases of the syn-dimers, the sensitizer-dimer ion-radical pairs undergo the rapid geminate recombination that works as a major energy dissipating channel responsible for the lower-than-unity quantum yields. It has been found that the presence of Mg(ClO4)2 at 0.1 M enhances approximately 1.5 times either the monomerization of the syn dimers or the formation of the chloranil anion radical. A laser-flash photolysis study shows that Mg2+ forms a complex with either the triplet or the anion radical of chloranil. The net salt effects are attributed to the retardation of the rapid geminate recombination by the participation of Mg2+ in the sensitizer-dimer ion-radical pairs.
Chloranil↗
[The effect of corticosteroid on lymphokine-activated killer (LAK) activity and the change of membrane antigen phenotype on PBMC after IL2 incubation with reference to the evaluation in vitro].
In the treatment of human cancer, the efficacy of the adoptive transfer of lymphokine-activated killer (LAK) cells combined with interleukin 2 (IL2) has been emphasized. However, administration of large doses of IL2 may cause significant adverse effects, such as "capillary leak syndrome". Moreover, the administration of corticosteroid may reduce the toxicity of IL2. However the efficacy of adoptive immunotherapy is abrogated by the administration of corticosteroid. In this context, the effect of corticosteroid on LAK activity and the change of membrane antigen phenotype on PBMC (peripheral blood mononuclear cells) was studied in vitro by using methylprednisolone (M-PSL). LAK cells were induced from PBMC, which had been separated from the peripheral blood of normal donors, and incubated with IL2 for 4 days. LAK activity was measured in a 4 h chromium release assay against K-562 cell and Daudi cell. The suppression of LAK activity by M-PSL depended on both concentration and working period of M-PSL. This inhibition was recognized even at rather low densities, such as 0.5 nmol/ml M-PSL. And the proliferation of PBMC after IL2 incubation, which was measured by incorporation of [3H]TdR, was reduced dose-dependently by M-PSL. In contrast, pretreatment within 24 hours of PBMC with M-PSL resulted in no effect on LAK activity. Furthermore M-PSL had no effect when added directly to a 4 h chromium release assay. The analysis of membrane antigen phenotype on PBMC was performed by the direct immunofluorescence method using FITC-labeled monoclonal antibodies. The proportions of T cells and NK cells, which were justified as precursors of LAK cells, increased after IL2 incubation both with and without M-PSL. Therefore no effect of M-PSL was confirmed in those circumstances. The ratio of HLA-DR (+) cells increased after IL2 incubation without M-PSL, while M-PSL reduced expression of this antigen. In contrast, IL2 receptor (CD25)(+) cells, markers of T cell and NK cell activation, significantly increased after IL2 incubation with or without M-PSL. These results suggest that the inhibitory effect of M-PSL on LAK activation was caused not by preventing a triggering process of activation of precursor cells, but by a possible inhibition of proliferation, though other effects of corticosteroid remain to be elucidated. Also, it is emphasized that caution should be exercised in the administration of corticosteroid in adoptive immunotherapy because of the inhibitory effect induced by M-PSL.
Antigens, Surface↗
Classification of the intrafusal muscle fibres in the frog muscle spindle: histochemical and immunofluorescent studies.
Intrafusal muscle fibres from bull-frog semitendinosus, iliofibularis and sartorius muscles were classified into three types using the histochemical, immunofluorescent and morphological characteristics, with reference to the extrafusal muscle fibres, which were classified into five types in accordance with Rowlerson & Spurway (1988). Immunofluorescent reactions with antibodies against slow or fast myosins obtained from anterior or posterior latissimus dorsi muscles (ALD or PLD), respectively, of chicken were used as the primary criterion. Histochemical profiles of muscle fibres were classified into nine types of myosin ATPase activity as the secondary criterion. Anti-PLD intrafusal fibres (polar zone) with ATPase profiles of moderate to high acid and alkaline stabilities correspond to large nuclear bag fibres in the classification of Diwan & Ito (1989), whereas anti-ALD fibres (polar zone) with alkaline-labile ATPase profiles correspond to medium nuclear bag fibres. On the basis of diameter, anti-PLD fibres (polar zone) with ATPase profiles of moderate to low acid stability and moderate to high alkaline stability seem to correspond to two types of small nuclear chain fibre. Variations between muscles, between intra- and extrafusal fibres and also between zones along intrafusal fibres are discussed.
Adenosine Triphosphatases↗
[High deposition rate of aluminum in tissues in diabetic hemodialysis patients].
Aluminum (Al) accumulation in bone is a serious problem in patients on hemodialysis. We studied deferoxamine infusion test (DFO test) in 14 diabetic patients on hemodialysis (HDDM) and 23 hemodialysis patients originated from glomerulo nephritis (HDCGN) to determine whether Al accumulation is different between the two groups or not. There was no difference in hemodialysis duration and total oral intake of Al containing drugs between two groups. Serum C-terminal parathyroid hormone (C-PTH) in HDDM was lower than that in HDCGN group (1.82 +/- 1.30 vs. 3.80 +/- 1.82 ng/ml; P less than 0.01). However serum Al (s-Al) levels were comparable (61.9 +/- 53.0 vs, 45.0 +/- 32.3 micrograms/l). A significant correlation was observed between duration of dialysis period and s-Al in HDDM (r = 0.806, p less than 0.01), but in HDCGN, the relation was not significant. The patients in HDDM whose cumulative aluminum intake was less than 2.0 kg showed the higher serum A1 concentrations before DFO and greater increases in s-Al after DFO test, as compared with those in HDCGN with matched aluminum intake (93.8 +/- 67.6 vs. 35.9 +/- 23.6 micrograms/l; p less than 0.001 and 141.2 +/- 81.8 vs. 70.3 +/- 41.1 micrograms/l; p = 0.035). These results indicate that in uremic diabetic patients with lower intake of Al containing drugs, an early accumulation of Al in the whole body occurs possibly because of the enhanced absorption rate of Al at an intestine and/or the low PTH level.
Adult↗
[Studies on 5-FU concentration and thymidine phosphorylase activity in tissues of patients with colorectal cancer after SF-SP administration].
5-fluorouracil (5-FU) concentrations in peripheral blood, portal blood, normal and cancer tissues were evaluated in 26 patients with colorectal cancer after SF-SP administration (800 mg/day for 10 days). Thymidine phosphorylase activity in cancer tissues was also evaluated. 5-FU concentration in cancer tissues was significantly higher than that in other three specimens, and much higher than 0.05 microgram/g which was reported to be the minimum effective concentration. 5-FU concentration in portal blood was lower than MEC (0.05 microgram/ml). As for the relationship with the pathological features of cancer, the protruding lesions showed a higher 5-FU concentration than the ulcerative ones, and the lesions invaded only to submucosa or proper muscle showed a higher concentration than others. 5-FU concentration ratio in cancer tissues per in peripheral blood (T/B ratio) was related to thymidine phosphorylase activity. The higher was the thymidine phosphorylase activity, the greater T/B ratio. The results suggest that the tumor with higher thymidine phosphorylase activity might have a more pronounced anticancer efficacy of 5-FU.
Colorectal Neoplasms↗
Cytoplasmic orientation and two-domain structure of the multidrug transporter, P-glycoprotein, demonstrated with sequence-specific antibodies.
The predicted cytoplasmic orientation and two-domain structure of the multidrug efflux pump P-glycoprotein were demonstrated with sequence-specific antibodies. We synthesized peptides corresponding to amino acid residues, Glu393-Lys408 (anti-P) and Leu1206-Thr1226 (anti-C) in P-glycoprotein from human mdr1 cDNA and used these peptides to produce polyclonal antibodies. From the primary structure of P-glycoprotein, and anti-C antibody is expected to recognize another position, Leu561-Thr581, in the duplicate structure of P-glycoprotein, but anti-P recognizes only one site. These antibodies bind to multidrug-resistant cells (KB-C2) with permeabilized plasma membrane but do not bind to nonpermeabilized KB-C2 cells or parental KB cells, supporting the predicted cytoplasmic orientation of these sequences. With immunoblotting of the membrane fractions from KB-C2 cells, a major 140-kDa polypeptide of the P-glycoprotein was detected with both anti-P and anti-C. Two minor polypeptides with molecular mass of 95 and 55 kDa were also detected. When membrane vesicles were digested mildly with trypsin, the amount of these two polypeptides increased. Anti-P detected only the 95-kDa polypeptide, and anti-C detected both 95- and 55-kDa polypeptides. Achromobacter lyticus protease I (lysyl endopeptidase) and Staphylococcus aureus V8 protease also produced two polypeptides with similar molecular weights. Absorption into lectin-agarose beads and labeling with [3H]glucosamine indicated that the 95-kDa polypeptide was glycosylated but that the 55-kDa polypeptide was not. These two polypeptides as well as P-glycoprotein were photoaffinity-labeled with a calcium channel blocker, [3H]azidopine, but most of the label was found in the 55-kDa polypeptide. The yield of labeled fragments from membrane vesicles photolabeled after digestion with trypsin was similar to that from membrane vesicles digested with trypsin after photolabeling. These data indicate 1) that the 95-kDa polypeptide is the fragment corresponding to the amino-terminal half of P-glycoprotein containing sugar chains; 2) that the 55-kDa polypeptide is the carboxyl-terminal half which was mainly labeled with [3H]azidopine; and 3) that P-glycoprotein has a relatively rigid structure with a small number of protease-sensitive sites and its global structure is not destroyed by tryptic cleavage.
ATP Binding Cassette Transporter, Subfamily B, Mem↗
Biosynthesis, processing and half-life of P-glycoprotein in a human multidrug-resistant KB cell.
The biosynthesis, processing, and half-life of the drug efflux pump, P-glycoprotein, were studied in human multidrug-resistant KB (KB-C2) cells selected for resistance to colchicine. An antibody directed against a synthetic oligopeptide corresponding to the amino-acid sequence (Glu-393-Lys-408) of P-glycoprotein from human mdr1 cDNA was prepared in rabbits. With immunoblotting and immunoprecipitation, we detected a 140-170 kDa protein in KB-C2 cells but not in parental sensitive KB cells. KB-C2 cells made a 125 kDa precursor that was slowly processed (t1/2 = 45 min) to the mature form of 140-150 kDa. The processing rate of P-glycoprotein was slower than that of low-density lipoprotein receptor. We detected another 160-180 kDa smear band, which might be a completely denatured form of P-glycoprotein. With immunoblotting, a minor band of high molecular mass (greater than 500 kDa) was also detected and this form increased after the cells were treated with chemical cross-linker, 1,5-difluoro-2,4-dinitrobenzene. The half-life of P-glycoprotein was long; no significant loss of P-glycoprotein was observed within 24 h after synthesis. Cells treated with tunicamycin produced a 120 kDa form of P-glycoprotein which was no longer processed but showed stability similar to that of the mature 140-150 kDa form. Agents that reverse multidrug resistance, phorbol ester and transport substrate did not affect the stability of P-glycoprotein.
ATP Binding Cassette Transporter, Subfamily B, Mem↗
Correlation between reversing of multidrug resistance and inhibiting of [3H]azidopine photolabeling of P-glycoprotein by newly synthesized dihydropyridine analogues in a human cell line.
Ten synthetic dihydropyridine analogues were investigated for their ability to reverse drug resistance in a multidrug-resistant human carcinoma cell line, KB-Cl. Four dihydropyridine analogues completely reversed the resistance, three lowered the resistance, and three had little effect. The radioactive photoactive dihydropyridine calcium channel blocker, [3H]azidopine, photolabels P-glycoprotein in membrane vesicles from KB-Cl cells. This photolabeling was almost completely inhibited by excess dihydropyridine analogues that reversed or lowered drug resistance. In contrast, the labeling was not significantly inhibited by analogues that do not reverse resistance. Among other reversing agents, cepharanthine and reserpine inhibited the [3H]azidopine photolabeling, but thioridazine did not. N-Solanesyl-N,N'-bis(3,4-dimethoxybenzyl)ethylenediamine slightly inhibited the labeling at 100 microM. An anticancer agent, vinblastine, also inhibited the labeling. The correlation between the reversing of the drug resistance and the inhibition of the [3H]azidopine photolabeling of P-glycoprotein by dihydropyridine analogues suggests a role for P-glycoprotein in multidrug resistance and also the reversing of the resistance by dihydropyridine analogues.
ATP Binding Cassette Transporter, Subfamily B, Mem↗
Insulin receptor and altered glucose transport in a monensin-resistant mutant of Chinese hamster ovary cell.
A monensin-resistant mutant Monr-31, derived from Chinese hamster ovary (CHO) cell line, has been shown to have a reduced number of insulin receptors and a reduction in glucose uptake in response to insulin. We have further investigated the possibility that altered glucose uptake in Monr-31 cells is related to an alteration in the activity of the insulin receptor. Uptake of glucosamine, 2-deoxy-D-glucose, and 3-O-methyl-D-glucose in Monr-31 cells was one-half to one-third that of CHO cells. The cellular content of the glucose transporter in Monr-31 was reduced to about one-third that of CHO as assayed by use of an antiglucose transporter antibody. After transfection with the human insulin receptor cDNA, we obtained clones CIR-0 from CHO, and MIR-2 and MIR-15 from Monr-31; CIR-0 expressed a tenfold higher level of the insulin-binding activity than did CHO, and MIR-2 and MIR-15 expressed a 20-fold higher level than did Monr-31. Glucose uptake in both CHO and CIR-0 was significantly enhanced by exogenous insulin, but not in Monr-31, MIR-2, and MIR-15. The beta-subunits of insulin receptor in CHO, CIR-0, Monr-31, and MIR-2 were similarly phosphorylated. The decreased glucose transport activity in Monr-31 cells is discussed in relation to the absence or presence of insulin receptor expression.
3-O-Methylglucose↗
Autoregulation of renal blood flow in streptozocin-induced diabetic rats.
Autoregulation of renal blood flow (RBF) was studied in male Wistar rats. We studied 11 control rats, 11 rats with severe streptozocin (STZ)-induced hyperglycemia (diabetic group), and 10 moderately hyperglycemic rats made diabetic by injection of STZ but given 2-8 U s.c. insulin daily (insulin-treated group). RBF was measured by an electromagnetic flowmeter during stepwise reduction of renal perfusion pressure 4-8 wk after injection of STZ (older group). RBF autoregulation of the diabetic group was impaired compared with the control group. In the insulin-treated group, autoregulatory capability was less attenuated than in the diabetic group. The average autoregulatory index (ARI) of the diabetic group (0.61 +/- 0.05) was greater than that of the control (0.24 +/- 0.02, P less than .01) and the insulin-treated (0.33 +/- 0.07, P less than .05) groups. To study the relationship between autoregulation and the duration of diabetes, an autoregulatory study was also made in a group of 22 rats (11 diabetic and 11 control) that were tested 2-3 wk after injection of STZ (younger group). The ARI in the younger diabetic group was smaller than that in the older diabetic group (P less than .05). The results suggest that in uncontrolled diabetes RBF fluctuates with blood pressure change, and protection against hypertensive injury of glomerular capillaries may be diminished. Autoregulatory disability develops with time, and insulin treatment diminishes impairment of autoregulation. These findings may also explain the adverse consequences of hypertension on the progression of diabetic nephropathy in poorly controlled diabetes.
Animals↗
[A molecular basis for multidrug resistance and reversal of the resistance].
Multidrug-resistance is frequently characterized by enhanced drug efflux resulting from a membrane glycoprotein of 170,000 daltons (P-glycoprotein). Analysis of cloned cDNAs for the human MDR 1 gene, whose product is the P-glycoprotein, indicates that P-glycoprotein is an energy-dependent drug-efflux system for cytotoxic hydrophobic anticancer drugs. We have demonstrated that a photoanalog of a reversing agent, SDB-ethylenediamine, specifically binds to P-glycoprotein. The binding site on P-glycoprotein seems to be identical with that of anticancer agents and other reversing agents. On the other hand, the radioactive photoactive dihydropyridine calcium channel blocker, [3H] azidopine, photolabels P-glycoprotein in membrane vesicles from multidrug-resistant cells. This photolabeling is almost completely inhibited by excess dihydropyridine analogs that reverse or lower drug-resistance. In contrast, the labeling is not significantly inhibited by analogs that do not reverse resistance. These results suggest that it may be possible to quickly screen for dihydropyridine analogs that reverse multidrug resistance by measuring the inhibition of [3H] azidopine labeling of P-glycoprotein.
ATP Binding Cassette Transporter, Subfamily B, Mem↗
Synthetic isoprenoid photoaffinity labeling of P-glycoprotein specific to multidrug-resistant cells.
The synthetic isoprenoid N-solanesyl-N,N'-bis(3,4-dimethoxy-benzyl)ethylenediamine (SDB) is known to reverse drug resistance in human multidrug-resistant KB cells. SDB inhibits the photolabeling of P-glycoprotein with the vinblastine analog N-(pazido-(3-(125)l)salicyl)-N'-beta-aminoethylvindesine. We synthesized photoactive radioactive SDB and used it to photoaffinity label membrane vesicles from human KB cells and their multidrug-resistant subline KB-C2 cells. A 150 to 170 kDa protein in membrane vesicles from KB-C2 cells was specifically labeled by the photoanalog of SDB. The labeled band was not detectable in parenteral drug-sensitive cells. The photolabeled 150 to 170 kDa protein was immunoprecipitated with a monoclonal antibody (C219) specific to P-glycoprotein. P-glycoprotein labeling was inhibited by anticancer agents, vinblastine, vincristine, actinomycin D, and daunomycin, with half-maximal inhibition at 2.0, 2.3, 18, and 23 microM, respectively. Only 33 and 18% of the labeling was inhibited by 100 microM Adriamycin and colchicine, respectively. The labeling was also inhibited by agents that reverse multidrug resistance, such as verapamil, reserpine, cepharanthine, and SDB. The existence of other molecules that specifically bind to 125l-SDB-photoanalog was suggested in both KB and KB-C2 membrane vesicles. The fact that we could identify the synthetic isoprenoid acceptor in membrane vesicles from multidrug-resistant cells confirms that P-glycoprotein plays a role in the multidrug resistance phenotype and provides an explanation for the fact that SDB circumvents multidrug resistance.
ATP Binding Cassette Transporter, Subfamily B, Mem↗
Organ distribution of 3H-endotoxin in rats with liver fibrosis and rats with liver cirrhosis.
The organ distribution of 3H-endotoxin was investigated in rats with CCl4-induced liver injury. Wistar male rats were given water containing phenobarbital (Controls), or were treated with water containing phenobarbital and CCl4 inhalation. Rats inhaling CCl4 for 6 weeks developed liver fibrosis (Group LF), while those inhaling it for 10 weeks developed liver cirrhosis (Group LC). Animals were killed and examined 24 hours after an intravenous injection of 3H-endotoxin (12,000 CPM/l g body weight). Compared with the control rats, the measured amount of 3H-endotoxin per unit weight of spleen, lungs, and blood increased, while that of the liver significantly decreased in the rats of groups LF and LC. These results suggest that endotoxemia may be enhanced by a diminished uptake of endotoxin by the liver in liver fibrosis and liver cirrhosis.
Animals↗
[Comparison of the different methods to calculate cerebral glucose utilization using F-18 FDG and PET].
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Aged↗