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M Seki

Publications and source records attributed to M Seki.

At least 379 records · Page 21Linked to original sources
PubMed1986

Purification and characterization of a deoxyribonucleic acid dependent adenosinetriphosphatase from mouse FM3A cells: effects of ribonucleoside triphosphates on the interaction of the enzyme with single-stranded DNA.

There are at least four forms of DNA-dependent ATPase in mouse FM3A cells [Tawaragi, Y., Enomoto, T., Watanabe, Y., Hanaoka, F., & Yamada, M. (1984) Biochemistry 23, 529-533]. One of these, ATPase B, has been purified and characterized in detail. During the purification of the enzyme, we encountered the difficulties that the enzyme could not be recovered well from the single-stranded DNA-cellulose column and that the enzyme activity was distributed very broadly. The problems were resolved by the addition of ATP in the elution buffer. The ATPase has a sedimentation coefficient of 5.5 S in both high salt and low salt. The enzyme hydrolyzes rNTPs and dATP, but ATP and dATP are preferred substrates. Adenosine 5'-O-(3-thiotriphosphate) (ATP-gamma-S), 5'-adenylyl methylenediphosphate (AMP-PCP), and 5'-adenylyl imidodiphosphate (AMP-PNP) inhibit the enzyme activity. The enzyme is insensitive to ouabain, oligomycin, novobiocin, and ethidium bromide. A divalent cation (Mg2+ congruent to Mn2+ greater than Ca2+) as well as a nucleic acid cofactor is required for activity. Poly(dT), single-stranded circular DNA, and heat-denatured DNA were very effective. Native DNA was little effective with an efficiency of 29% of that obtained with heat-denatured DNA. In addition, the enzyme showed almost no activity with poly(dA).poly(dT) although it showed very high activity with the noncomplementary combination of poly(dT) and poly(dC), suggesting that ATPase B requires single-stranded DNA for activity. ATP altered the affinity of ATPase B for single-stranded DNA. The interaction of the enzyme with DNA was studied by Sephadex G-200 gel filtration assay.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Triphosphatases↗
PubMed1986

Detection and characterization of a novel factor that stimulates DNA polymerase alpha.

A novel factor that stimulates DNA polymerase alpha activity on poly(dA) X oligo(dT) has been identified and partially purified from mouse FM3A cells. The assay system for the factor contained poly(ethylene glycol) 6000. The activities of DNA polymerase alpha on poly(dA) X oligo(dT) in the presence and absence of the stimulating factor were increased greatly by the addition of poly(ethylene glycol). Stimulation by the factor was observed at all the primer to template ratios tested from 0.01 to 0.3. The highest activity was observed at the ratio of 0.05, corresponding to about 3.3 primers on one template in the presence of the factor. The concentration of DNA polymerase alpha used in the assay affected the stimulation by the factor, and the stimulation became more prominent at concentrations of the enzyme lower than 0.04 unit per assay. The stimulating factor lowered the Km value of DNA polymerase alpha for the template-primer, though they had no effect on the Km value for dTTP substrate. The results of product analysis suggested that the stimulation by the factor is mainly due to the increase in the initiation frequency of DNA synthesis from the primers. The stimulating factor specifically stimulated DNA polymerase alpha but not DNA polymerases beta and gamma. Furthermore, the factor formed a complex with DNA polymerase alpha under a certain condition.

Animals↗
PubMed1986

Nature of leukemic stem cells in murine myelogenous leukemia.

We investigated the nature of myelogenous leukemic stem cells in mice. L-8057, a megakaryoblastic leukemia cell line used in this study, produces in vivo and in vitro colonies. By means of typical chromosomal aberrations in L-8057, one can conveniently detect the origin of the cells in each colony derived from a leukemic stem cell. Direct evidence of whether cells from each colony had leukemogenicity in recipient mice was successfully obtained by the colony transplantation assay. Both leukemic colony-forming unit-spleen (L-CFU-s) and leukemic colony-forming unit-culture (L-CFU-c) in L-8057 may have belonged to the same differentiating stage in the stem cells because of their similar radiosensitivity, although some parts of the L-CFU of L-8057 seemed to have lost their capability to regenerate L-CFU-s when the cells were plated in dishes. This leukemic stem cell preserves high self-renewal ability in vitro after 10 passages. In addition, in vitro colony formation by this leukemic cell during the above course of serial passages did not require any additional exogenous stimulators. The same sort of trials have been made on other types of leukemias. Leukemic stem cells showed remarkable variety in their response to stimulating factors and in their self-renewal activity, which suggests that they may have consisted of heterogeneous populations.

Animals↗
PubMed1986

Guinea pig complement fixation by tissues from hypocomplementaemic renal diseases.

Recently many studies have been done to identify complement pathway activation in renal tissue from patients with renal disease. We examined whether tissues obtained by renal biopsy from such patients would fix guinea pig complement. Nine out of 15 patients with systemic lupus erythematosus (SLE), 4 out of 7 patients with mesangiocapillary glomerulonephritis (MCGN), and 2 out of 7 cases with acute glomerulonephritis (AGN) fixed guinea pig C3. We found that tissues from 5 out of 9 guinea pig C3-positive SLE cases fixed guinea pig C4, while none of the guinea pig C3-positive tissues from patients with MCGN or AGN fixed guinea pig C4. These guinea pig C3-positive renal tissues were further studied for interaction with C4-deficient guinea pig serum, EDTA guinea pig serum, heated guinea pig serum, and EGTA Mg2+ guinea pig serum. The results indicated that activation of both the alternate and classical complement pathways occurred with tissues from patients with SLE, while activation of the alternate pathway occurred with MCGN and AGN. Results for tissues from AGN and MCGN patients indicated the presence of C3 convertase and protease which interacted with guinea pig C3.

Biopsy↗
PubMed1986

Intra-arterial infusion chemotherapy in combination with angiotensin II for advanced bladder cancer.

A combination of 50 to 80 mg. per m.2 cis-platinum and 30 to 50 mg. per m.2 doxorubicin or 30 to 50 mg. per m.2 tetrahydropyranyl-doxorubicin instead of doxorubicin was infused into the bilateral internal iliac artery for the treatment of 20 patients with T3 or T4 advanced bladder cancer. Angiotensin II was administered together with these chemotherapeutic agents by means of an infusion pump at a rate of 1.5 to 2.0 micrograms. per minute for 20 minutes for both sides. Among the 20 patients complete (9) and partial (8) responses were obtained after only 1 or 2 courses of this intra-arterial treatment. Histological examination showed severe tumor destruction with no viable cells in 6 and no tumor in 4 of the 15 evaluable cases. Selective enhancement of regional blood flow in the tumor region after intra-arterial infusion of angiotensin II was observed by continuous target arterial 81mkrypton infusion. Intra-arterial chemotherapy with combined angiotensin II may be clinically useful for treatment of primary or metastatic bladder carcinoma.

Adult↗
PubMed1986

[A long-term survivor of primary hepatoma--a case suggesting the superiority of a multi-drug (OK-432, SPG, PSK) over mono-drug immunotherapy].

The studied patient (70 years old, male) had primary hepatoma with rupture of the liver. We resected his left lobe partially and were able to save him. Since a residual tumor was found after surgery, we injected a total of 30 mg of MMC into the SCA 3 times. Under continuous administration of OK-432, the patient survived for 3 years and 6 months in remission. Because the tumor grew gradually, we started a multi-drug immunotherapy (OK-432 5 KE/2 W/intradermal, PSK/3.0 g/day/P.O., SPG/20 mg/2 W/I. M.) which we have advocated. In 6 months the tumor regressed to 1/3 of its original size. The patient is currently in good condition 4 years and 7 months after the operation. This case demonstrated the superiority of multi-drug immunotherapy over single-drug immunotherapy.

Aged↗
PubMed1986

[Toxicological studies on (2''R)-4'-O-tetrahydropyranyladriamycin, a new antitumor antibiotic. Its acute toxicity in beagle dogs].

(2"R)-4'-O-Tetrahydropyranyladriamycin (THP), a new antitumor antibiotic of anthracycline derivative, was given intravenously to male and female Beagle dogs, followed by observations for 2 weeks. The doses were 0.125, 0.25, 0.5 and 1.0 mg/kg. Observations were performed on mortality, clinical signs, body weight and temperature, food and water consumption, ECG, ophthalmoscopy, testicular measurement, hematology, serum biochemistry, urinalysis, autopsy, histopathology and electron microscopy. The results were as follows. All animals of 1 mg/kg-treated group died but there were no deaths in other groups. All the levels of doses caused vomiting and diarrhea. Furthermore, the highest dose caused bloody diarrhea and decreases in food consumption, motility and body weight, followed by death. These effects may be related to histopathological changes in mucosa of digestive tract. Some changes in water consumption, urine volume and renal histopathology were sporadically observed after treatment, but they were not treatment-related. These results suggest that a treatment with THP does not significantly cause renal disturbance. There were no treatment-related changes in body temperature, ophthalmoscopical observation and testicular measurement. THP produced flattening of T wave and prolongation of QRS interval only at high doses of more than 0.5 mg/kg for males and of 1 mg/kg for females but did not cause any histopathological or electron microscopical changes in hearts. It seems that the abnormalities caused by THP in ECG traces are due to the deterioration of general conditions rather than the direct effect on heart. High doses produce the significant changes in platelet, WBC, Hb, Neutro. (Seg.), Mono., Hb, RBC and Lymph. and further regressive changes in thymus, spleen and bone marrow. These results suggest that THP causes some effects on hemopoietic tissues. The sporadic changes in serum biochemistry and urinalysis were neither related to the treatment nor to the changes in organ weight, autopsy, histopathology and electron microscopy. Therefore, it is likely that THP does not cause toxicological effect on the other tissues and organs except hemopoietic tissues.

Animals↗