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Biomedical subjects

K Takagi

Publications and source records attributed to K Takagi.

At least 631 records · Page 35Linked to original sources
PubMed1987

Changes of phospholipase A2 inhibitory activity in the K+-sensitive actin gelation factor during the differentiation of myeloid leukemia cells.

The phospholipase A2 inhibitory activity of a 38 kDa K+-sensitive actin gelation factor in a murine leukemia cell line (M1) was examined. A specific antibody against 38 kDa protein was found to cross-react with 37 kDa protein (lipocortin) in rat peritoneal exudates. Although the native 38 kDa protein from M1 cells did not block phospholipase A2 activity, pretreatment with alkaline phosphatase produced a form that did inhibit this enzyme. However, a purified 38 kDa protein from differentiated M1 cells blocked phospholipase A2 activity without pretreatment with alkaline phosphatase. Phospholipase A2 inhibitory activity of the 38 kDa protein was not altered by addition of actin. These findings suggest that the phospholipase A2 inhibitory of our 38 kDa protein was induced during differentiation. We also proposed that our 38 kDa protein has the same epitope as lipocortin.

Actins↗
PubMed1987

Early gastric carcinoma with special reference to macroscopic classification.

During a period beginning in 1946 and ending in October of 1978, 1000 cases of solitary early gastric carcinoma were operated on at the Cancer Institute Hospital, Tokyo, Japan. The clinical characteristics and the macroscopic and chronological changes were studied in these cases. Early gastric carcinoma comprised one third of all resected gastric carcinoma. If early gastric carcinoma was divided into two groups, the depressed and the elevated, the former was more common. By location, the depressed type lesions were more frequently seen in the middle third of the stomach and the elevated type lesions in the lower third. By age, distribution of the elevated type lesions showed a peak with a mode at the age of 60 to 69 years and of the depressed type, a plateau with a mode at the age of 50 to 59 years. The relative incidence of the elevated type of gastric carcinoma to the depressed type was one to four. In depth of invasion, the mucosa and the submucosa were equally involved. Lymph node metastases were encountered in 12.7% of early gastric carcinoma cases. The incidence of positive nodes in mucosal carcinoma was 3.4% and that of submucosal lesions was 21.7%. Of the elevated type carcinoma, 20.9% of the cases had positive nodes. The 5-year survival rate of the patients with surgery for cure was 93.8% in contrast to 56.5% of those with palliative resection.

Aged↗
PubMed1987

Surgical treatment of gastric cancer today.

The utilization of radical operation in gastric cancer cases has led to the development of various operation techniques. With the improvement in perioperative management it can be said that age no longer is a restriction. A study of gastric cancer prognosis indicates an upward trend in survival since 1960 along with the increased detection of early cancer. This suggests the most importance of early detection in increasing the therapeutic results obtained in cases of gastric cancer. In cases with advanced cancer, 5-year survival rate of 44.7 per cent was attained through such aggressive actions as extended dissection of lymph nodes and combined resection of surrounding organs with evaluation of the macroscopic classification of the cancer.

Follow-Up Studies↗
PubMed1987

Dissociation kinetics of 19 base paired oligonucleotide-DNA duplexes containing different single mismatched base pairs.

The dissociation kinetics of 19 base paired oligonucleotide-DNA duplex containing a various single mismatched base pair are studied on dried agarose gels. The kinetics of the dissociation are first order under our experimental conditions. The incorporation of a single mismatched base pair destabilizes the DNA duplexes to some extent, the amount depending on the nature of the mismatched base pair. G-T and G-A mismatches slightly destabilize a duplex, while A-A, T-T, C-T and C-A mismatches significantly destabilize it. The activation energy for the overall dissociation processes for these oligonucleotide-DNA duplexes containing 19 base pairs is 52 +/- 2 Kcal mol-1 as determined from the slope of Arrhenius plot.

Base Composition↗
PubMed1987

Management of thoracic outlet syndrome.

The experience with transaxillary first-rib resection and scalenotomy reported herein shows these to be safe and effective treatments for patients with thoracic outlet syndrome (TOS). The former operation usually offers the best possibility for complete resection of the first rib and all anomalous congenital bands, and is curative in most cases, regardless of the mechanism of the compression. Scalenotomy, or Powers' operation, is also helpful, in particular for cases of TOS with a vertebral arterial insufficiency. Accurate diagnosis of TOS and selection for surgery after a detailed history and proper physical examination will result in gratifying relief of symptoms in almost all patients with TOS.

Adult↗
PubMed1987

Relaxant effects of forskolin on guinea pig tracheal smooth muscle.

We investigated the relaxant effects of forskolin, a diterpene derivative isolated from the roots of Coleus forskohlii, on guinea pig airway smooth muscle by measuring the isometric tension of tracheal smooth muscle in vitro and transcutaneous Po2 during the histamine inhalation test (HIT) in vivo. Forskolin (10(-9)-10(-5) M) caused dose-dependent relaxant effects on resting tone and on leukotriene C4 (10(-7) M)-, leukotriene D4 (10(-7) M)-, and carbachol (3 X 10(-6) M)-induced contraction of tracheal smooth muscle. Moreover, with propranolol pretreatment the relaxant effect of forskolin on tracheal smooth muscle did not change, whereas with the same pretreatment the relaxant effect of isoproterenol diminished. Forskolin (10(-8)-10(-6) M) raised tissue cyclic AMP levels dose-dependently in tracheal smooth muscle (6.7-359.9 pmol/mg protein). Forskolin (1 mg/kg) administered subcutaneously raised the respiratory threshold of (RT-histamine in the HIT. The determination of the RT-histamine by measuring tcPo2 was possible without anesthesia. These results suggest that forskolin relaxes airway smooth muscle in guinea pigs in vitro and in vivo by raising tissue cyclic AMP levels and that its actions are independent of beta-adrenoceptors.

Animals↗
PubMed1987

The role of phospholipase in beta-agonist-induced down regulation in guinea pig lungs.

It has been observed that repeated and prolonged beta-agonist treatment causes the impairment of beta-adrenergic function, so-called "desensitization" or "down regulation". To clarify the mechanism of down regulation, the following experiment was performed using guinea pig lungs. Animals were divided into four groups: In the metaproterenol groups, guinea pigs were treated with metaproterenol (10 mg/kg/day) by intraperitoneal injection once a day for 1 day or for 7 successive days In the control groups, guinea pigs were treated with saline by the same procedure as in the metaproterenol groups. In the group treated with metaproterenol for 7 days, there was a 45% reduction in the number of beta-adrenoceptors and a 62% reduction in adenylate cyclase activity, compared with those of the control group. However, there were no significant changes in the dissociation constant (Kd) of the receptors. On the other hand, no reduction in the number of beta-adrenoceptors and adenylate cyclase activity was observed in the group treated with metaproterenol once a day for 1 day, compared with those of the control group. Phospholipase (PLase) activity in the lung microsomes of guinea pigs injected with metaproterenol for 1 day and for 7 days was elevated by 14.4 and 33.1%, respectively, compared with that of the control groups. Phospholipid contents of lung membranes prepared from the animals treated with metaproterenol for 7 days were significantly decreased compared with those of the control group, though in the group treated with metaproterenol once a day for 1 day, phospholipid contents did not differ from those of the control. Lung membranes treated with PLase A2 revealed decreases both in the number of beta-adrenoceptors and adenylate cyclase activity, dose dependently. These results and the fact that membrane phospholipids are involved in the beta-adrenoceptor system suggest that down regulation observed during beta-agonist administration is, at least in part, attributed to degradation of phospholipids of lung membranes by the persistent activation of PLase in the tissue.

Adenylyl Cyclases↗
PubMed1987

Characterization of "abp38" in cytoskeleton of mouse myeloid leukemia cells and distribution of abp38 in various tissues.

A specific antibody was prepared against "abp38," a 38 kDa-dimer protein purified from mouse myeloid leukemia cells (M1 cells), that induce gelation of actin filaments in a K+-dependent manner. Immunochemically, the total content of abp38 in undifferentiated M1 cells was found to be 0.89% of the total protein (10.7 micrograms/10(7) cells). This content increased about 8-fold (89.5 micrograms/10(7) cells) after the M1 cells had differentiated into macrophages. When the cells before differentiation were extracted with Triton solution containing 150 mM KCl, almost all abp38 in the cytoskeleton was removed, whereas in cells after differentiation, amount of abp38 remaining in the cytoskeleton was 4.5 micrograms per 10(7) cells. The amount of cytoskeleton-bound abp38 of M1 cells and mouse peritoneal macrophages decreased with increase in K+ concentration in the extraction solution. Immunoreactive molecules against abp38 antibody were present in various tissues and cultured cell lines except for skeletal muscle and erythrocytes. Furthermore, actin binding protein with a molecular size of 38 kDa was found in bovine brain. These data suggest that abp38 is a ubiquitous protein present in various tissues and species.

Amino Acids↗
PubMed1987

Dephosphorylation of "abp38" protein during the differentiation of mouse myeloid leukemia cells.

We have characterized the phosphorylation of "abp38" before and after the differentiation of mouse myeloid leukemic cells (M1 cells). The abp38 of both undifferentiated and differentiated M1 cells contained phosphoserine and phosphotyrosine. The extent of phosphorylation of abp38 decreased to about 30% of the value of undifferentiated cells during cell differentiation; phosphoserine and phosphotyrosine decreased to 41 and 11% of the values before differentiation, respectively.

Actins↗
PubMed1987

Comparative studies on the combined cytotoxic effect of forskolin with mitomycin C and responsiveness to forskolin in rat ascites hepatoma AH66 cells and AH66F cells.

The combined cytotoxic effect of forskolin with mitomycin C (MMC) was investigated using two cell lines, AH66 and AH66F. Forskolin significantly enhanced the cytotoxicity of MMC and increased the uptake of MMC and the intracellular adenosine 3',5'-cyclic monophosphate (cyclic AMP) level in AH66 cells but similar results were not obtained with AH66F cells. Dibutyryl cyclic AMP enhanced the effect and uptake of MMC in both cell lines. These results confirm that elevated cyclic AMP in the cells increases the cellular uptake of MMC and enhances the cytotoxicity of MMC as reported in our previous papers. Therefore, forskolin may be suitable for antitumor combination therapy. On the other hand, the functional components associated with the cyclic AMP generating system were thought to be present in membranes of both AH66 cells and AH66F cells from results that showed that cholera toxin, islet-activating protein and prostaglandin E1 increased the level of cyclic AMP in both cells. The elevation of cyclic AMP by these adenylate cyclase activators in AH66 cells was augmented by forskolin. However, the cyclic AMP level in AH66F cells was scarcely affected by forskolin and the elevation of cyclic AMP by the activators was inhibited by this diterpene. From these results, it appears that the AH66F cell line may be useful for the elucidation of the action mechanism of forskolin and of the transmission system from hormone receptors to adenylate cyclase.

Animals↗
PubMed1987

Multiform combination effects of smooth muscle relaxants with antitumor agents in rat ascites hepatoma AH66 cells.

At non-cytotoxic concentrations, actions of smooth muscle relaxants except for the action of isoproterenol (IPN) on the effect of vinblastine (VBL) and mitomycin C (MMC) in rat ascites hepatoma AH66 cells resistant to these antitumor agents clearly separated into two groups. IPN hardly influenced the effects of both VBL and MMC. Although verapamil, a calcium-antagonist, and W-7, a calmodulin inhibitor, enhanced the growth-inhibitory effect and uptake of VBL by inhibiting the VBL efflux, these drugs did not influence the effect and uptake of MMC. In contrast, forskolin, an adenylate cyclase activator, db-cAMP, a cAMP analog, and theophylline, a cyclic nucleotide phosphodiesterase inhibitor, potentiated the effect of MMC, but did not influence the effect of VBL. The combination effect of forskolin and db-cAMP might be elucidated from the increase of inward transport of MMC through the action of the intracellular cAMP elevated by these drugs. Theophylline, however, only slightly increased both intracellular cAMP level and MMC uptake into the cells, similar to the action of IPN. We thought that the combination effect of theophylline was effected through its other activity of repair inhibition against AH66 cells, which are resistant to MMC due to their high capacity to repair impaired DNA. Thus, the smooth muscle relaxants used in this study enhanced the growth-inhibitory effect of a distinct antitumor agent through their individual activity against tumor cells.

Animals↗