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M Inaba

Publications and source records attributed to M Inaba.

At least 145 records · Page 8Linked to original sources
PubMed1987

Thymic rudiments are responsible for induction of functional T cells in nu/nu mice.

Congenitally athymic nude (nu/nu) mice have been thought to exhibit no T cell functions despite the presence of some Thy-1 positive (Thy-1+) cells. However, we detected a significant number of Con A-responsive cells in spleens of nu/nu mice after the age of 2 months when the spleen cells were cultured in a medium containing 5% human plasma or human serum, but not when they were cultured in fetal calf serum. Cytotoxic test using anti-Thy-1.2 antibody plus complement has revealed that these Con A-responsive cells are indeed Thy-1+. The Con A-responsive T cells increase with age. PHA-responsive and alloreactive T cells are also detected in the spleens of 11-month-old nu/nu mice. To probe the origins of the T-lymphocytes of the nu/nu mice we examined extensively and systematically the thymic remnants in the mediastinum and neck region of the nu/nu mice in search for T cell development in thymic rudiments. In these investigations we regularly found small accumulations of cells comprising almost entirely Thy-1+ lymphocytes surrounding accumulations surrounded by epithelial cells. These findings suggest that apparent sites of T cell development in thymic rudiments are indeed present in nude mice and appear to be functioning to induce expression T cell markers on precursor cells in the lymphoid lineage. Together with our prior findings the evidence presented in this report shows that a pathway exists in nude mice. In the converse these findings suggest that the thymus is the sole site for induction of the differentiation of stem cells or precursor T cells into mature T-lymphocytes. The findings suggest that indications of alternative differentiation pathways for T-lymphocytes must seek the location of these pathways within the thymus itself.

Aging↗
PubMed1987

Energy metabolism in canine erythrocytes associated with inherited high Na+- and K+-stimulated adenosine triphosphatase activity.

Energy metabolism in canine erythrocytes associated with inherited high Na+- and K+-stimulated adenosine triphosphatase [(Na,K)-ATPase] activity (HK cells) was compared with that in normal canine erythrocytes (LK cells). Activities of some of the glycolytic enzymes in the HK cells were significantly higher than those in LK cells. The concentrations of adenosine triphosphate (ATP) and glycolytic intermediates in HK cells were almost equal to those in LK cells. Glucose utilization and lactate production by HK cells in vitro and incorporation of [32P]orthophosphate or [14C]glucose into 2,3-diphosphoglycerate in HK cells were higher than in LK cells. Radioactivity of [32P]ATP in HK cells was lower than in LK cells, but increased to approximately that of LK cells when (Na,K)-ATPase of HK cells was completely blocked by ouabain. When HK cells and LK cells were incubated in the absence of glucose, the concentration of ATP in HK cells was decreased more than that of LK cells. Although ouabain reduced the rate of decrease in ATP in HK cells, the decrease in ATP in HK cells was still 2-fold that in LK cells. The half-life of HK cells was about one-half that of LK cells. The results indicated that glycolysis is greater in HK cells than in LK cells, and that the increased glycolysis in HK cells was stimulated by an increased rate of ATP breakdown for active cation transport by the (Na,K)-ATPase and by increased degradation of ATP for some other pathway, eg, glutathione synthesis. Thus, the increased demand for ATP in HK cells might result in shortening the lifespan of HK erythrocytes.

Animals↗
PubMed1987

Kinetic analysis of active efflux of vincristine from multidrug-resistant P388 leukemia cells.

Kinetic analysis of vincristine transport in parental and multidrug-resistant P388 leukemia cells was attempted by indirect assessment of its efflux. Practically, the initial velocity and steady-state level of vincristine uptake by ATP-depleted cells, and its steady-state level in untreated cells, were measured. As a result, a saturable process of not only influx but also efflux of vincristine was observed for the first time with both cell lines, suggesting the existence of a carrier-mediated system for influx and efflux. With increasing extracellular drug concentrations, the contribution of the mediated transport to the total flux was decreased and that of the unsaturable process, that is, simple diffusion, was increased. It should be particularly noted that the Km and Vmax values of efflux in the resistant cells were significantly less and greater, respectively, than those of the sensitive cells, providing a biochemical basis for enhanced efflux as a mechanism of multidrug-resistance. No significant difference in kinetic parameters of vincristine influx and intracellular binding contributing to resistance was found between the two cell lines.

Animals↗
PubMed1987

Successful pancreatic allografts in combination with bone marrow transplantation in mice.

We have established a new method for pancreatic allografts in mice by combining pancreatic transplantation with allogeneic bone marrow transplantation. In this approach, we first transplanted bone marrow to induce tolerance to both donor-type and host-type major histocompatibility complex (MHC) determinants. Pancreatic tissue from the same mouse strain as bone marrow donor was then grafted under the renal capsule. Acceptance of the grafts was confirmed by histopathological and immunohistochemical techniques. BALB/c mice reconstituted with C57BL/6J bone marrow cells accepted pancreatic tissue from both bone marrow donor (C57BL/6J)-type and host (BALB/c)-type mice. An immunohistochemical study revealed the presence of functional islets under the renal capsules. Assays for both mixed lymphocyte reaction (MLR) and induction of cytotoxic T lymphocytes indicated that the newly developed T cells are tolerant of both donor (stem cell)-type and host-type MHC determinants. By contrast, the T cells of these chimeras showed a significant responsiveness to third party MHC determinants. These findings suggest that pancreatic allografts combined with bone marrow transplantation may become a viable strategy for the treatment of patients with diabetes or patients who have undergone pancreatectomy.

Animals↗
PubMed1987

[Quantitative analysis of cell-kill effects of anticancer drugs: consideration of both in vitro and in vivo experimental systems].

After examining the in vitro cell-kill kinetics of various anticancer drugs by using cultured human cell lines, Shimoyama et al. classified the drugs into two groups according to the types of action: 1) type-I drugs (cytocidal and concentration-dependent action) such as alkylating agents and anticancer antibiotics; 2) type-II drugs (cytostatic and time-dependent action) such as antimetabolites, Vinca alkaloids and L-asparaginase. In the present paper, we will present a rational basis for such a classification by using cell-kill pharmacodynamic models, and consider the optimal dosage regimen depending on the type of drugs by combining the cell-kill kinetic and pharmacokinetic models. In these models, classification of the drugs depends on whether the cell population is kinetically homogenous or not. It is assumed that cell population is homogenous for type-I drugs and there exist both drug sensitive and insensitive cell populations for type-II drugs. The concentration (or dose)-time-cell survival curves in both in vitro and in vivo, which are simulated based on the kinetic models, are consistent with the experimental data found in the literature. Further analysis on the optimal dose regimen according to these kinetic models clarified that the type-I drugs showed a similar cell-kill effect irrespective of the mode of administration as long as the area under the plasma unbound concentration curves (AUCp, free) is kept constant, while the type-II drugs are more effective by multiple dosing or infusion regimen than single administration of a large dose of drugs. In other words, the extents of AUCp, free and the residence time in the plasma (above certain concentrations of drugs) are determinants of the in vivo cell-kill effects of type-I drugs and type-II drugs, respectively. If the pharmacokinetics of newly developed anticancer drugs in human are predicted from the animal data according to the so-called "animal scale-up" technique and combined with the in vitro cell-kill kinetic data by the use of proposed kinetic models, one may obtain not only the optimal dosage regimen but also good screening systems for truly active drugs for the treatment of human cancer.

Antineoplastic Agents↗
PubMed1987

[Studies on the mechanism of multidrug resistance].

We have introduced two different approaches which we have introduced recently in an attempt to understand the mechanism of multidrug resistance, which was shown to be successfully reversed using non-antitumor analogs of anthracycline and vinca alkaloid. This approach was adopted on the basis of our hypothesis that these substances can inhibit the accelerated drug efflux of the resistant cells. On the other hand, we found that such efflux consists of a saturable as well as an unsaturable process using our newly-designed kinetic approach. In addition, greater Vmax and lower Km were found in the saturable process of efflux in resistant cells as compared with those in sensitive cells. In conclusion, these results suggest that broad cross-resistance among structurally unrelated drugs, i.e., multidrug resistance, is associated with an efflux-oriented transport carrier with broad affinity for these lipophilic drugs with a polycyclic structure.

Animals↗
PubMed1987

Increased thromboxane B2 excretion in diabetes mellitus.

Thromboxane (TX) A2 is a potent vasoconstrictor as well as a proaggregator of platelets. Augmented TXB2 platelet synthesis and attenuated vascular prostacyclin formation have been demonstrated in diabetes mellitus. We undertook to establish a simple method of extracting urinary TXB2 (UTXB2) and to elucidate the pathophysiologic role of renal TXA2 in diabetes mellitus. One-step extraction of UTXB2 with an octadecylsilyl-silica column was sufficient as pretreatment for TXB2 radioimmunoassay because recovery of UTXB2 was good, the eluate was parallel with the dose-response curve, and the value coincided with that obtained by the conventional method. When platelet TXA2 synthesis was completely suppressed by administration of 100 mg aspirin, urinary TXB2 excretion (UTXB2V) declined to 41% of the initial levels, suggesting that renal TXA2 formation contributes significantly to UTXB2V. UTXB2V was 94.5 +/- 14.0 ng/day or 108.8 +/- 17.3 ng/gm creatinine in controls. Approximately half of the patients with diabetes demonstrated a UTXB2 level higher than the mean + 2 SD level of controls. Although UTXB2V did not show a significant correlation with protein excretion, UTXB2V in patients with diabetes with proteinuria greater than 100 mg/day was augmented (224.4 +/- 30.5 ng/day) compared with that in patients with diabetes without proteinuria greater than 100 mg/day. Furthermore, UTXB2V correlated negatively with the p-aminohippuric acid clearance rate, but not with the creatinine clearance rate. The results suggest that renal TXA2 synthesis may be augmented in diabetic nephropathy and may play a pathophysiologic role in renal hemodynamics as well as in protein excretion.

Adult↗
PubMed1987

Methionine toxicosis in cats.

Cats given DL-methionine (1 g/kg of body weight/day) developed severe hemolytic anemia with marked increase of methemoglobin (MetHb) concentration and Heinz-body formation at treatment-day 6 to 10. Cats fed 0.5 g of methionine/kg for 52 days had a moderate Heinz-body hemolytic anemia with methemoglobinemia at treatment days 17 to 31, but thereafter recovered from the anemia despite continuation of methionine feeding, indicating an adaptation of the cats. In vitro, significant (P less than 0.01) increases of MetHb concentration and Heinz-body formation were observed when RBC were incubated with plasma from cats fed (1 g of methionine/kg) or with 10 mM 3-methylthiopropionate, a product of methionine catabolism. However, these increases were not observed when RBC were incubated with 10 mM methionine. Seemingly, excessive methionine intake leads to production of an intermediate of the methionine catabolism that may affect RBC directly as an intensive oxidizing agent, resulting in an excessive oxidation of hemoglobin to MetHb and Heinz-body formation.

Amino Acids↗
PubMed1986

Na,K-ATPase in dog red cells. Immunological identification and maturation-associated degradation by the proteolytic system.

The Na,K-ATPase of red cells from high K+ and low K+ dogs was studied immunologically by using antibodies raised against dog kidney enzyme. Anti-alpha subunit IgGs, which also recognized alpha (+) from brain enzyme, identified the larger subunit of erythrocyte Na,K-ATPase as a homogeneous polypeptide with Mr = 96,000 on sodium dodecyl sulfate-polyacrylamide gel electrophoresis followed by immunoblotting. In addition, erythrocyte Na,K-ATPase, purified by immunoaffinity chromatography on a monoclonal antibody-coupled column, showed the identity of its polypeptide composition to that of the renal enzyme. Furthermore, it was shown that reticulocyte lysates from high K+ and low K+ dogs substantially degraded 125I-Bolton-Hunter reagent-labeled Na,K-ATPase. This degradation of the enzyme protein was significantly enhanced by the addition of ATP and Mg2+. These results indicate that dog reticulocytes possess some mechanism for protein breakdown involving an ATP-dependent proteolytic system, resulting in the dramatic breakdown of Na,K-ATPase activity during dog reticulocyte maturation into erythrocytes (Maede, Y., and Inaba, M. (1985) J. Biol. Chem. 260, 3337-3343).

Animals↗
PubMed1986

Calcitonin-induced phosphorylation of rat liver cytosolic proteins.

Calcitonin (CT) stimulated phosphorylation of two liver cytosolic proteins whose molecular weights are 67,000 and 93,000. Stimulation of 67,000-Mr protein phosphorylation began shortly after subcutaneous injection of CT, reaching a maximum at 5 min and decreasing to below the control level at 30 min. The reaction was independent of cyclic AMP or Ca2+, and was not influenced by a calmodulin antagonist, W7. Stimulation of 93,000-Mr protein phosphorylation became evident by 30 min. This reaction was also stimulated by administration of vasopressin or epinephrine, which is known to cause increased phosphorylation of glycogen phosphorylase having the same molecular weight. The phosphorylation of 93,000-Mr protein, stimulated by CT, was dependent on Ca2+ but not on cyclic AMP, and appeared to be inhibited by W7. In addition, CT did not influence the phosphorylation of 61,000-Mr protein, a major protein phosphorylated in a cyclic AMP-dependent manner. These results suggest that CT may exert its effect on liver cells through protein phosphorylation, most probably in a cyclic AMP-independent manner.

Animals↗
PubMed1986

Concentrations of thyroxine-binding globulin in sera and peritoneal dialysates in patients on chronic peritoneal ambulatory dialysis.

Losses in thyroxine-binding globulin (TBG) in peritoneal dialysate and thyroid function were evaluated in patients undergoing continuous ambulatory peritoneal dialysis (CAPD), in comparison to patients on hemodialysis (HD) without TBG loss in the dialysate. The TBG concentration in the peritoneal dialysate was 0.26 +/- 0.09 microgram/ml (mean +/- SD, n = 24), with a daily loss of 2.47 +/- 0.94 mg. The serum TBG level in CAPD patients was 21.0 +/- 4.71 micrograms/ml (n = 24), which was not significantly different from that in HD patients (20.0 +/- 5.72 micrograms/ml, n = 24) or in healthy Japanese subjects. The serum TBG level correlated positively with the TBG loss and TBG level in the peritoneal dialysate (p less than 0.001). The serum T4 level in CAPD patients (4.93 +/- 1.38 microgram/dl, n = 24) was significantly greater than in HD patients (4.08 +/- 1.30 microgram/dl, n = 24, p less than 0.05).

Adult↗
PubMed1986

Polyamines in 1 alpha, 25-dihydroxycholecalciferol-induced differentiation of human promyelocytic leukemia cells, HL-60.

The human promyelocytic leukemia cell line, HL-60, differentiated into macrophage/monocytes in the presence of 1 alpha,25-dihydroxycholecalciferol [1 alpha,25(OH)2D3], as assessed by the percentage of morphologically mature cells and their ability to reduce nitroblue tetrazolium. In this study of the mechanism involved, the activities of ornithine decarboxylase and spermidine/spermine-N1-acetyltransferase (SAT), the rate-limiting enzymes of polyamine metabolism, as well as the cellular levels of polyamine were measured. ODC activity reached a peak 24 h after the addition of 1 alpha,25(OH)2D3 and then decreased, while SAT activity gradually increased as differentiation commenced. An increase in putrescine and decreases in spermidine and spermine were also observed. Addition of alpha-difluoromethylornithine, an irreversible inhibitor of ODC, with or without methylglyoxalbis(guanylhydrazone), an inhibitor of S-adenosylmethionine decarboxylase, caused no effect on 1 alpha,25(OH)2D3-induced cell differentiation, although the cellular levels of putrescine and spermidine decreased markedly. Addition of alpha-difluoromethylornithine markedly suppressed cell proliferation; this effect was reversed by the addition of exogenous putrescine. Addition of exogenous spermidine or spermine to overcome activation of SAT also had no effect on 1 alpha,25(OH)2D3-induced cell differentiation. These results suggest both that polyamine metabolism is not important in 1 alpha,25(OH)2D3-induced differentiation of HL-60 cells, but that it is intimately involved in the proliferation of these cells.

Acetyltransferases↗
PubMed1986

A case of normocalcemic primary hyperparathyroidism with osteomalacia.

A 59 year-old patient had lumbago and pain in hip joints, knees, and ribs of long duration. Severe hypophosphatemia and high serum ionized calcium were found in spite of normal level of total serum calcium. The serum parathyroid hormone and alkaline phosphatase levels were elevated, and diffuse demineralization of the bones and renal stones were found by x-ray examination. Parathyroid adenoma was diagnosed from the subtraction image of the 99mTc O-4 and 201Tl-Cl2 scintigrams. Osteomalacia was demonstrated by bone biopsy at the right iliac crest. A right lower parathyroid adenoma of 2.0 X 1.8 cm, weighing 4.0 g was removed. The long standing phosphate depletion and hypophosphatemia, due to hyperparathyroidism causing renal damage with nephrocalcinosis and reduced synthesis of active vitamin D, and milk tolerance due to gastroduodenostomy were probably responsible for producing the clinical picture of normocalcemic hyperparathyroidism complicated with osteomalacia.

Adenoma↗
PubMed1986

Selective reduction of intracellular guanosine 5'-triphosphate pool by 4-carbamoylimidazolium 5-olate in murine tumor cells.

Ehrlich carcinoma and P388 leukemia cells were rendered resistant to 4-carbamoylimidazolium 5-olate (SM-108), and assessments were made of biochemical and pharmacological determinants for the sensitivity to SM-108 using both sensitive and resistant sublines. We observed that the treatment of cells with SM-108 in vitro caused a remarkable decrease in the intracellular guanosine 5'-triphosphate pool level in sensitive but not in resistant sublines. There was no difference in the ability to take up SM-108 between sensitive and resistant sublines, but the cellular conversion of SM-108 to its nucleotide, which is the putative active anabolite of SM-108, proceeded only in sensitive sublines. Enzymological studies revealed that the activity of adenine phosphoribosyltransferase (EC 2.4.2.7), which is believed to conjugate SM-108 with 5-phospho-alpha-D-ribose 1-diphosphate, was very low in the resistant sublines. These results strongly support our previous hypothesis that SM-108 is activated by adenine phosphoribosyltransferase to SM-108-nucleotide which then inhibits hypoxanthine-5'-monophosphate dehydrogenase (EC 1.2.1.14), a key enzyme for the de novo synthesis of guanosine 5'-monophosphate.

Adenine Phosphoribosyltransferase↗
PubMed1986

Evaluation of response rates to various antitumor agents of human gastric tumors implanted in nude mouse.

To ascertain the clinical predictability and, in the long run, the usefulness of the human tumor/nude mouse model as a screening tool for antitumor agents, it seems particularly important to use as many tumor lines as possible and to evaluate the therapeutic effectiveness of antitumor agents in terms of the overall response rate of a range of tumors. In this study, using 11 strains of established human gastric tumor xenografts with various histological characteristics and proliferation behavior, the experimental response rates to 8 typical antitumor drugs (mitomycin C, cyclophosphamide, ACNU, cisplatin, adriamycin, vincristine, vinblastine and 5-fluorouracil) were determined and compared with the clinical values. The experimental response rates to adriamycin, vincristine and 5-fluorouracil were in good accordance with the clinical results. However, with the other drugs, significantly higher response rates were observed with the nude mouse model as compared to clinical therapy, indicating that this model tends to overestimate the responsiveness of human tumor to a number of antitumor agents. These results strongly suggest the importance of using appropriate dose levels in the nude mouse to reproduce clinically equivalent effects in this model.

Animals↗
PubMed1986

Non-antitumor vinca alkaloids reverse multidrug resistance in P388 leukemia cells in vitro.

Twelve monomeric or dimeric alkaloids from Vinca rosea Linn., which had been reported to have little or no antitumor activity, were investigated to determine their combined effects with either vincristine or daunorubicin on in vitro cell growth of a P388 subline resistant to vincristine and cross-resistant to anthracyclines. We found that the combinations at subcytotoxic concentrations induced significant growth inhibition of the resistant cells, but not of the sensitive cells. Of the alkaloids examined, catharine, vindoline, catharanthine, vincarodine, and lochnerine were able to bring about complete inhibition of cell growth. Further in vitro study using vindoline revealed that at 10 micrograms/ml it was able to completely reverse not only resistance to vincristine but also cross-resistance to vinblastine, daunorubicin, and adriamycin. In addition, we found that vinca alkaloids active in reversing resistance possess potent activities to enhance the net uptake of not only vincristine but also daunorubicin by the resistant cells, and this effect was proved to result from their inhibitory action on the active efflux process. These results provide further support for our hypothesis that both anthracyclines and vinca alkaloids can inhibit their own efflux process by interacting with the cell membrane, and this similarity provides a basis for their reciprocal cross-resistance, irrespective of their different chemical structures.

Animals↗
PubMed1986

[Growth-inhibitory activity of minocycline on various tumor cell lines in vitro].

In order to investigate the possible mechanism for the therapeutic efficacy of tetracycline antibiotics against malignant pleural effusion, the effect of minocycline (MC), one of this type of antibiotic, on in vitro growth of tumor cells was examined. As a result, it was found that MC caused complete growth inhibition of various tumor cell lines at concentration of 10-20 micrograms/ml, but this action was reversible, suggesting that considerably long exposure time would be needed for these drugs to kill the tumor cells in vivo at a relatively low concentration. On the other hand, when a relatively high concentration of 100 micrograms/ml was applied, MC induced irreversible inhibition of cell growth even if the exposure time was comparatively short. Since 4 human lung tumor cell lines examined exhibited high sensitivity to these antibiotics, it seems possible that their direct administration in the form of a high-concentration solution into the pleural cavity would result in a direct cytostatic effect on tumor cells in clinical therapy.

Animals↗