Search PubMed⌕ Search

Biomedical subjects

M Inaba

Publications and source records attributed to M Inaba.

At least 289 records · Page 16Linked to original sources
PubMed1990

Kinetic analysis of 5-fluorouracil action against various cancer cells.

Based on our recent kinetic analysis, which made it possible to distinguish between the cell-killing actions of cell cycle phase-specific and non-specific agents, we attempted to elucidate the actions of 5-fluorouracil (FUra) on three different cancer cell lines. By colony-forming assay, the concentrations of fluorouridine (FUrd), fluorodeoxyuridine (FdUrd) or FUra giving 90% cell kill (IC90) at various exposure times (texps) were obtained. With P388 cells, the curve of texps-IC90 for FUrd on a log-log scale was linear with a slope of -1, which is typical for cell cycle phase-nonspecific agents. In contrast, the curve for FdUrd showed a much steeper slope than -1, which is characteristic for cell cycle phase-specific agents. We found that the curve for FUra was exactly the same as that for FUrd, indicating that the mode of FUra action on P388 leukemia is analogous to that of FUrd. Similar results were observed with human colon and renal cancer cell lines, HT-29 and KU-2, although when the cells were exposed to relatively low concentrations of FUra for a long time, a cell cycle phase-specific action became evident.

Animals↗
PubMed1990

Hyperreninemia due to increased renal renin synthesis in BioBreeding Worcester rats.

It is well known that diabetes mellitus is often associated with hypertension. We previously reported the unresponsiveness of renin release to volume depletion with impaired renal prostaglandin E2 synthesis in rats with streptozotocin-induced diabetes. However, we have found that BioBreeding Worcester rats, spontaneously susceptible to diabetes mellitus either before or after the onset of diabetes, showed a pronounced fourfold to ninefold increase in plasma renin activity in comparison with control Wistar rats. Furthermore, these rats developed mild hypertension as high as 134 mm Hg after the age of 90 days. The hyperreninemia responded to 1-week sodium loading or restriction; the blood pressure increased during sodium loading. Oral administration of captopril (30 mg/kg) for 1 week resulted in a large blood pressure decrease (-47.1 +/- 5.9 mm Hg, n = 10) in comparison with controls (-17.0 +/- 4.7 mm Hg, n = 12). Vascular response to angiotensin II was also attenuated. Plasma angiotensin II levels were 5.7-fold higher and associated with a 1.5-fold increase of plasma aldosterone concentration compared with control rats, whereas angiotensinogen-plasma concentrations were lower than in control rats. The renal renin content determined enzymatically or histochemically was more enhanced in BioBreeding Worcester rats than in control rats, but the renal renin messenger RNA levels did not differ. These results suggest that the strain-specific hyperreninemia in BioBreeding Worcester rats might be due to posttranscriptional abnormalities of renal renin synthesis. Further work is needed to elucidate the specific mechanism or mechanisms responsible.

Angiotensin II↗
PubMed1990

Thymic dendritic cells and B cells: isolation and function.

The thymus is the primary organ in which T cells undergo rearrangement of T cell receptor alpha and beta genes, positive selection for affinity to self MHC products, and elimination (negative selection) of reactivity to self antigens. These events require an interaction of the developing T cell with other cell types in the thymus. The latter include epithelial cells, macrophages, dendritic cells, and the recently described thymic B cells the majority of which are CD5+. Here we review the identification and isolation of thymic dendritic cells and CD5+ B cells. We consider phenotype, ontogeny, and function, including possible contributions to the induction of self tolerance. Thymic dendritic cells are similar to spleen dendritic cells, but are larger and exhibit a few differences in phenotype. Dendritic cells from both organs are equally potent accessory cells for the MLR and lectin-induced, T cell proliferation. Thymic dendritic cells have higher levels of Fc receptors and support anti-CD3 dependent mitogenesis. Thymic CD5+ B cells share phenotypic features with peritoneal CD5+ B cells. However thymic B cells neither proliferate nor form antibody producing cells in response to the stimulation with LPS or anti-IgM plus IL-4, but do respond to stimulation with MHC class II-restricted helper T cells. Thymic dendritic cells and CD5+ B cells both appear at a similar time in ontogeny, about 14 d of gestation, which is the time T cell differentiation begins to take place. Dendritic cells from spleen, which are potent activators for peripheral T cells, are also potent inactivators for thymic-derived cytotoxic T cells. A correlation between reactivity to MIs products and the expression of TCR-V beta genes is well documented, and B cells are the primary APC for this antigen. Therefore, thymic CD5+ B cells may be a good tool for the investigation of tolerance to M1s products.

Animals↗
PubMed1990

[Antitumor activity of polyanion and its application for drug delivery system of antitumor drugs].

Polyanionid copolymer of divinyl ether and maleic anhydride (DIVEMA) with narrow molecular weight distribution was synthesized and tested of its antitumor activity. DIVEMA showed a significant antitumor activity against colon 26 adenocarcinoma and FSaI fibrosarcoma transplanted in syngenic mice. Furthermore, DIVEMA was used as a polymeric drug carrier of antitumor drugs to reduce side effects and enhance the antitumor activity of the drugs. Adriamycin and neocarzinostatin were attached covalently to DIVEMA and the polymeric conjugates showed higher antitumor activity than the corresponding mother drugs against P 388 leukemic mice.

Adenocarcinoma↗
PubMed1990

Histogenesis of hemopoietic bone marrow in adult mice.

Based on the concept that the hierarchy of regulatory genes may specify mammalian development, we attempted to evaluate how morphological and functional phenotypes of hemopoietic bone marrow develop in murine models. From studies of local irradiation, s.c. implantation of bone with or without marrow, and renal subcapsular implantation of marrow plugs or bone without marrow, we identified four sequential (necrotic, clearing, stromal proliferating, and hemopoiesis-recovering) responses in the early phase of the reconstruction of hemopoietic marrow that spatially and temporally proceeded in this restricted order. In addition, characteristic hexagonal sinuses were found to participate in the development of hemopoietic marrow in the early phase. The development of hexagonally arranged sinuses seems to coincide with the formation of abundant osseous trabeculae and to precede the appearance of colony-forming units in culture (CFU-C) and spleen colony-forming units (CFU-S). These findings are discussed from the point of the hierarchy of regulation.

Animals↗
PubMed1989

O-N-acetyl-D-glucosamine moiety on discrete peptide of multiple protein 4.1 isoforms regulated by alternative pathways.

Erythrocyte protein 4.1 is a cytoplasmic protein that possesses a protein-saccharide modification structure, an O-N-acetyl-D-glucosamine (GlcNAc) moiety. We determined the amino acid sequence of the proteolytic fragment containing the O-GlcNAc moiety after labeling the saccharide with [3H]galactose in the presence of bovine milk galactosyltransferase. Glycosylation appears to occur on one or more serine or threonine residues in the following sequence: Thr-Ala-Gln-Thr-Ile-Thr-Ser-Glu-Thr-Pro-Ser-Ser-Thr-Thr-Thr-Thr-Gln-Ile-Thr-Lys . This sequence corresponds to the carboxyl-terminal half of the 34-amino acid peptide in the 22/24-kDa carboxyl-terminal domain of protein 4.1, which is one of the discrete peptides regulated by alternative RNA splicing. Multiple protein 4.1 isoforms in erythroid and nonerythroid cells including major components of erythrocyte membrane proteins, 4.1a and 4.1b, appear to contain this sequence since most immunochemically reactive proteins were labeled with [3H]galactose, with the exception of several variant polypeptides. These results appear to suggest the functional or biological significance of the O-GlcNAc linkage in protein 4.1.

Acetylglucosamine↗
PubMed1989

Evaluation of antitumor activity in a human breast tumor/nude mouse model with a special emphasis on treatment dose.

Eight lines of human breast tumors implanted in nude mice were treated with various antitumor agents at two different doses, maximum tolerated doses (MTD) and rational doses (RD) that were pharmacokinetically equivalent to the clinical doses; the response rates to both doses were compared. With MTD, the response rates to mitomycin C and vinblastine were 100%, and those to other agents including cyclophosphamide, nimustine (a water-soluble nitrosourea), vincristine, Adriamycin (doxorubicin; Adria Laboratories, Columbus, OH), 5-fluorouracil (5-FU), and methotrexate were 30%-50%, indicating high responsiveness to the former two agents. In contrast, when the RD were used, the response rates to the majority of these agents were 25%-40%, and those to vincristine and nimustine were 13% and 0%, respectively. These results agree with the reported clinical results compared with those with MTD, suggesting the importance of the use of clinically equivalent doses in the evaluation of antitumor efficacy in a human tumor/nude mouse system.

Animals↗
PubMed1989

A new hypoglycemic agent, midaglizole, blunts diabetic platelet aggregation: a possible role of alpha 2 blockade.

A newly developed alpha 2 blocker, midaglizole (DG-5128, 2-[2-(4,5-dihydro-1H-imidazol-2-yl)-1-phenylethyl] pyridine dihydrochloride sesquihydrate) has been shown to have a hypoglycemic action in healthy controls as well as in diabetics. Since human platelets are rich in alpha 2 receptors, the effects of midaglizole on platelet aggregation were investigated. In normal controls, ADP- or epinephrine-induced platelet aggregation was significantly inhibited 2 h after oral administration of 300 mg midaglizole. Midaglizole also suppressed diabetic platelet aggregation stimulated by 10 or 100 microM epinephrine and delayed the initiation of collagen-induced aggregation at 30 micrograms/ml. In vitro addition of midaglizole at 9 or 90 microM significantly inhibited epinephrine-induced platelet aggregation. Furthermore, long-term administration of midaglizole suppressed diabetic platelet aggregation induced by 0.5-1 microM ADP or 1 microM epinephrine. These results suggest that alpha 2 blockade not only blunts diabetic epinephrine-induced platelet aggregation but also affects ADP- or collagen-stimulated platelet aggregation, indicating that this alpha 2 blocker may offer a new approach to the treatment of diabetic microangiopathy.

Adrenergic alpha-Antagonists↗
PubMed1989

Immunological identification of 1,25-dihydroxyvitamin D3 receptors in human promyelocytic leukemic cells (HL-60) during homologous regulation.

Immunological techniques were utilized to detect 1,25-dihydroxyvitamin D3 (1,25-(OH)2D3) receptor levels and to characterize physical/chemical changes in receptors in human promyelocytic leukemic cells (HL-60) during continuous exposure to hormone. The monoclonal antibody (IVG8C11) raised against the porcine intestinal 1,25-(OH)2D3 receptor immunoprecipitated quantitatively 1,25-(OH)2D3 receptors in nuclear extracts from HL-60 cells. The highly enriched immunoprecipitated receptors were electrophoresed on sodium dodecyl sulfate-polyacrylamide gels and transferred to polyvinylidene difluoride membranes, which were probed with 125I-labeled IVG8C11. The basal receptor from the cells treated with 1,25-(OH)2D3 for 2 h was detected as a single form at 53 kDa. Moreover, receptors were shown to be up-regulated at 12 h and down-regulated at 48 and 72 h in the continuous presence of hormone as evidenced by the ratio of density of the bands, 1.0 (2 h):4.2 (12 h):1.2 (48 h):0.9 (72 h), as measured by laser scanning densitometry. The up- and down-regulated receptors were also detected as single forms and had the same molecular mass as the basal receptor. Therefore, the data presented here strongly support the hypothesis of homologous regulation of 1,25-(OH)2D3 receptors in intact human target cells.

Antibodies, Monoclonal↗
PubMed1989

Corneal endothelial changes in pseudoexfoliation syndrome.

Using specular microscopy and computer-assisted morphometry, we studied 27 eyes with pseudoexfoliation syndrome, 17 apparently normal fellow eyes, and 15 eyes of matched normal subjects with no ocular disease other than senile cataract. Endothelium of the eyes with pseudoexfoliation syndrome showed significantly lower cell density than did the endothelium from control eyes. Endothelium of both eyes of patients with unilateral pseudoexfoliation syndrome showed significant morphologic changes in cell size (polymegethism) and shape variability (pleomorphism); these changes were essentially the same in overtly affected and apparently normal fellow eyes. The results suggested that the corneal endothelial changes are consistent and might serve as an early sign of the disorder.

Cell Count↗
PubMed1989

Kinetic analysis of cell killing effect induced by cytosine arabinoside and cisplatin in relation to cell cycle phase specificity in human colon cancer and Chinese hamster cells.

We presented a cell kill pharmacodynamic model for cell cycle phase-specific antitumor agents as well as that for cell cycle phase-nonspecific agents. The former was based upon assumptions that a cell population could be divided into a drug-sensitive population having sensitive (or specific) cell cycle phase(s) and a drug-resistant population in resistant cell cycle phases. This model revealed that cell killing action of antitumor agents with sufficient cell cycle phase specificity was time dependent. This time dependence was actually observed with cytosine arabinoside by colony-forming inhibition assays using Chinese hamster V79 cells. On the other hand, the present analysis indicated that cell killing effects of drugs lacking cell cycle phase specificity are dependent on C x T (concentration-time product). We analyzed cell kill kinetics of cisplatin and showed C x T dependence of cell killing action of the drug using human colon cancer WiDr cells. These results indicate that cell killing action of antitumor agents can be kinetically analyzed in terms of cell cycle phase specificity.

Animals↗
PubMed1989

In vivo circumvention of vincristine resistance in mice with P388 leukemia using a novel compound, AHC-52.

A novel compound partially analogous to nifedipine, AHC-52, was found to sensitize multidrug-resistant tumor cells. AHC-52 at 0.5 microgram/ml completely reversed the in vitro resistance to vincristine (VCR) in VCR-resistant P388 cells (P388/VCR). Of various regimens examined for the in vivo treatment of P388/VCR-bearing mice, the combination of 0.05 mg/kg of VCR with 100 mg/kg twice a day of AHC-52 daily demonstrated the best result with a 206% increase in life prolongation. This result was comparable with that observed in parental P388-bearing mice treated with the optimal dose of VCR alone, indicating almost complete circumvention of resistance by combination VCR-AHC-52 therapy. In addition, the combination of both agents exhibited therapeutic effects in the treatment of P388-bearing mice with some long term survivors. This result was presumably due to the elimination of heterogeneity of VCR sensitivity in this cell population. These results suggest that combination chemotherapy using a sensitizing agent such as AHC-52 will be effective in not only circumvention of multidrug resistance but also retardation of its occurrence.

Animals↗
PubMed1989

The effect of hard contact lens wear on the keratoconic corneal endothelium after penetrating keratoplasty.

Using wide-field specular microscopy, we evaluated the morphologic features of the corneal endothelium in 14 eyes of 14 patients with keratoconus who had worn a polymethylmethacrylate hard contact lens for at least four years (mean, 71 months) after penetrating keratoplasty. Comparisons were made with 14 non-lens-wearing eyes of 14 patients with keratoconus matched for age, length of postoperative period, and other variables. Examination of the endothelium of the contact lens wearers showed a significantly higher coefficient of variation in cell size (polymegethism) and a marked decrease in the percentage of hexagonal cells (pleomorphism), with a significant decrease in cell density (P less than .05). The cause of these morphologic abnormalities remains unclear but may be related to lens-induced hypoxic stress to the corneal endothelium causing ongoing cell loss.

Cell Count↗
PubMed1989

Stabilization of 1,25-dihydroxyvitamin D-3 receptor in the human leukemia cell line, HL-60, with diisopropylfluorophosphate.

We have investigated the reason for the lack of specific 1,25-dihydroxyvitamin D-3 binding activity in extracts of ATCC HL-60 cells. Although intact ATCC HL-60 cells specifically and saturably take up 1,25-dihydroxy[3H]vitamin D-3, whole cell extracts have little or no specific binding of 1,25-dihydroxyvitamin D-3. The absence of specific binding can now be explained by the action of a serine proteinase in these cells. When diisopropylfluorophosphate (DFP), a potent inhibitor of serine proteinase, is added to the buffer used for extraction, specific binding of 1,25-dihydroxy[3H]vitamin D-3 in the extract is observed. The loss of specific binding could not be prevented by hydrolyzed DFP or other serine proteinase inhibitors, such as phenylmethylsulfonylfluoride, benzamidine and aprotinin. The proteolytic activity from ATCC cells also destroyed specific 1,25-dihydroxy[3H]vitamin D-3 binding in high-salt extracts from pig intestinal nuclei or from another HL-60 cell line (LG HL-60 cells). However, the proteinase did not affect the levels of the specific binding in these preparations if the receptor was occupied with 1,25-dihydroxy[3H]vitamin D-3 prior to exposure to the proteinase. The binding and sedimentation characteristics of the receptors from various sources were not changed by the presence of DFP. The Kd of the receptor in ATCC HL-60 cells is 1.2.10(-10) M, which is identical to that in the LG HL-60 cells. The 1,25-dihydroxy[3H]vitamin D-3 receptor complex from the ATCC cells sediments as a single 3.5 S component and elutes from DNA-Sephadex column in two peaks at 0.09 and 0.15 M KCl. The material eluting at 0.15 M KCl has the same DNA-binding activity as preparations from pig intestine or LG HL-60 cells. Immunoprecipitation studies demonstrated that monoclonal antibodies to the pig receptor, IVG8C11, quantitatively precipitate the 1,25-dihydroxy[3H]vitamin D-3-binding activity from ATCC HL-60 cells as well as that from LG HL-60 cells or pig intestinal nuclei. Therefore, the previous failure to demonstrate the 1,25-dihydroxyvitamin D-3 receptor in ATCC HL-60 cells is because of the presence of a potent serine proteinase and not because of an abnormal or absent receptor.

Calcitriol↗
PubMed1989

Kinetic analysis of the in vitro cell-killing action of neocarzinostatin.

The relationship between the drug concentration and exposure time of neocarzinostatin (NCS) for a definite cell-killing effect was kinetically analyzed, taking into consideration its loss in biological activity during incubation. Its cell-killing activity was determined by a colony-forming inhibition assay, which was conducted at room temperature (25 degrees C) for 0.5-30 min exposure and at 37 degrees C for 5 min - 96 h exposure. Drug degradation at both temperatures was also investigated by bioassay. NCS lost its biological activity much faster at 37 degrees C than at 25 degrees C and the rate of loss in activity was higher at the lower initial concentration. Thus, the initial NCS concentrations necessary for 90% cell kill corresponding to each exposure time and a drug degradation constant were applied to a mathematical equation for the cell-killing effect of cell-cycle-phase-nonspecific agents. As a result, the curves for IC90-exposure time relationships predicted from drug degradation constants for 37 degrees C and 25 degrees C were fairly well fitted to the respective experimental data. These results indicate that the cell-killing action of NCS can be expressed by this mathematical equation with scrutiny of drug degradation and is dependent on the concentration-time product (C x T).

Animals↗