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Biomedical subjects

A Yoshimura

Publications and source records attributed to A Yoshimura.

At least 253 records · Page 14Linked to original sources
PubMed1990

[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↗
PubMed1990

[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↗
PubMed1989

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↗
PubMed1989

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↗
PubMed1989

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↗
PubMed1989

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↗
PubMed1989

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↗
PubMed1989

[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↗
PubMed1989

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↗
PubMed1989

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↗
PubMed1988

Novel feature of metabolism of low density lipoprotein receptor in a mouse macrophage-like cell line, J774.1.

Biosynthesis, processing, and degradation of low density lipoprotein (LDL) receptors were studied in a mouse macrophage-like cell line, J774.1, by immunoprecipitation and immunoblotting with an antibody directed against the COOH-terminal 14 amino acids of the LDL receptor. The molecular weight of the mature LDL receptor of J774.1 cells maintained in RPMI medium was 140,000 under nonreducing condition and 160,000 under reducing condition in sodium dodecyl sulfate-polyacrylamide gels. These sizes are 10,000-15,000 daltons larger than those of the receptor in other mouse fibroblastic cells or P388 leucocyte. However, when J774.1 cells were cultured in Dulbecco's modified Eagle's medium, the molecular weight of the mouse cell lines, 123,000 under nonreducing condition and 153,000 under reducing condition. The larger LDL receptor molecules produced by J774.1 cells cultured in RPMI were insensitive to the treatment with end-alpha-N-acetylgalactosaminidase (O-glycanase), suggesting that aberrant serine/threonine-linked (O-linked) glycosylation might account for the apparent large size. Pulse-chase experiments revealed that the rate of processing of the LDL receptor from precursor to mature form in J774.1 was similar to that in other mouse cell lines, but the rate of degradation was much faster: half-life of the LDL receptor of J774.1 was about 2 h. No significant difference in biological function or lifetime was observed between the normal and the larger LDL receptor. This novel character of molecular size and lifetime of the LDL receptor in J774.1 is discussed in relation to altered maturation and/or modification during receptor biosynthesis.

Animals↗
PubMed1988

Estrogen inhibits the growth of MCF-7 cell variants resistant to transforming growth factor-beta.

Human breast cancer MCF-7 cells containing estrogen receptor are killed by transforming growth factor-beta (TGF-beta). We isolated variants of MCF-7 highly resistant to TGF-beta. Variants ES-1 and ES-4 were cloned, and the growth of ES-1 and ES-4 was found to be inhibited by estradiol, whereas estradiol stimulated the growth of the parental MCF-7 cells. ES-1 cells contained about 2-fold higher level of estradiol receptor than MCF-7 cells. Addition of estradiol to the culture medium for MCF-7 and the variant changed the expression of several secreted proteins. The repertoire of secreted proteins was markedly altered in the variant. Polypeptides of molecular weight 52,000 (52 K), 65 K and 160 K were increased about 10- to 50-fold in both estradiol-treated MCF-7 and ES-1 cells. Polypeptide of 130 K was decreased in estradiol-treated ES-1 cells while this polypeptide was increased about 4-fold in estradiol-treated MCF-7, as compared with untreated MCF-7. Polypeptide of 100 K was specifically secreted in ES-1 whether or not estradiol was present, but there appeared to be no significant amount of the 100 K protein in MCF-7. The estradiol-hypersensitive phenotype is discussed in relation to its aberrant expression of secreting proteins.

Breast Neoplasms↗
PubMed1988

Cardiotonic activity of 5-methyl-6-(4-pyridyl)-2H-1,4-thiazin-3(4H)-one hydrochloride (ZSY-27).

Cardiotonic activity of a new, non-catecholamine and non-glycoside positive inotropic agent, 5-methyl-6-(4-pyridyl)-2H-1,4-thiazin-3(4H)-one hydrochloride (ZSY-27), was investigated in isolated guinea pig left atria, cat right ventricular papillary muscle and cross-circulated excised dog papillary muscle preparations, and in anesthetized open-chest dogs. In electrically driven guinea pig left atria and cat papillary muscle preparations, ZSY-27 (3 x 10(-6)-10(-4) M) increased the developed tension in a concentration-related manner. The positive inotropic effect of ZSY-27 was not blocked by propranolol (3 x 10(-8) M) in the guinea pig atria, but was significantly inhibited by carbachol (5 x 10(-6) M) in cat papillary muscle preparations. The positive inotropic effect of ZSY-27 was comparable to that of milrinone in guinea pig atria. ZSY-27 (0.01-3 mg) increased dose-dependently the developed tension in cross-circulated excised dog papillary muscle preparations as well. In anesthetized dogs, ZSY-27 (0.03-1 mg/kg, i.v.) produced a dose-dependent increase in left ventricular contractile force and a decrease in blood pressure, while the increase in heart rate was relatively small. The pharmacological profile of ZSY-27 in anesthetized dogs was similar to that of milrinone. These results suggest that ZSY-27 is potent cardiotonic agent with vasodilator activity and its effect may be partially due to an increase in the intracellular adenosine 3',5'-cyclic monophosphate level.

Animals↗