Search PubMed⌕ Search

Biomedical subjects

S Ikegami

Publications and source records attributed to S Ikegami.

At least 91 records · Page 5Linked to original sources
PubMed1989

Recovery of hippocampal cholinergic activity by transplantation of septal neurons in AF64A treated rats.

Embryonic septal neurons were transplanted into the hippocampus of adult rats which had received lateral-ventricular administration of AF64A, a cholinergic neurotoxin, and the effects on hippocampal cholinergic activity were studied. One week after AF64A administration, we injected dissociated septal cell suspension into the dorsal hippocampus, unilaterally. About 3 months after the transplantation, acetylcholine (ACh)-rich septal grafts formed extensive acetylcholinesterase (AChE)-positive fibers into the host hippocampus, recovering choline acetyltransferase (ChAT) level only in the grafted side. These results indicate that septal implants can produce a partial recovery of the cholinergic activity in the chemically damaged hippocampus.

Acetylcholinesterase↗
PubMed1989

RNA synthesis in starfish embryos: developmental consequences of its inhibition by formycin.

Embryos of the starfish Asterina pectinifera were examined with regard to their ability to undergo the early events of embryonic development in the presence of formycin, an analogue of adenosine and a reported inhibitor of RNA synthesis. It was shown that in normal embryos the pool of ribonucleoside 5'-triphosphates increased during the period of blastula formation. The increase of the UTP pool was blocked nearly completely by 25 micrograms/ml formycin, and that of the CTP pool was inhibited partially by the same concentration of the drug. On the other hand, the pools of ATP and GTP were the same for both control and formycin-treated embryos. The development of embryos cultured in the presence of 25 micrograms/ml formycin stopped at the early blastula stage. Addition of 100 micrograms/ml each of uridine and cytidine to cultures of embryos that had been placed in 25 micrograms/ml formycin at the onset of blastulation allowed gastrulation to occur, suggesting that the developmental arrest produced by formycin is due primarily to the inhibition of pyrimidine nucleotide biosynthesis.

Animals↗
PubMed1989

Mouse Ly-31.1 is an alloantigenic determinant of alkaline phosphatase predominantly expressed in the kidney and bone.

The mouse lymphocyte surface alloantigen, Ly-31, defined by monoclonal antibody N1.10 (IgG2b,k) and controlled by a gene locus closely linked to the Akp-2 locus on chromosome 4, was biochemically investigated. By employing a quantitative immunoassay system, it was found that the Ly-31.1-specific antibody detected an allotypic determinant of mouse alkaline phosphatase. Ly-31.1, i.e., mouse alkaline phosphatase, was expressed predominantly in kidney and bone and was also detected in placenta, lung, and testis. Concerning tumor cell lines, they varied in the amount of antigen present, with both T and B lymphoid lineages selectively possessing the antigen. In normal lymphoid tissues, lesser amounts of antigen were detected. The binding of mouse alkaline phosphatase to Ly-31.1-specific monoclonal antibodies was specific in nature. The Ly-31.1 antigen was immunoprecipitated from the lysates of surface-radiolabeled YAC-1 moloney leukemia cells, and appeared as a single band of about 78,000 under both reduced and nonreduced conditions on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Furthermore, treatment of tumor cell lines with phosphatidylinositol-specific-phospholipase C resulted in the removal of Ly-31 antigen from the cell surface. These results suggest that a gene cluster containing the Ly-31 and Akp-2 loci which control the alkaline phosphatase is formed on mouse chromosome 4. The Ly-31 antigen is the first enzyme demonstrated to be a lymphocyte surface alloantigen.

Alkaline Phosphatase↗
PubMed1989

Blocking of cytotoxic T-cell function of MOLF/Ei mice by anti-Ly 35.1 monoclonal antibody.

Ly 35.1 antigen is an alloantigen expressed only on T cells of Mus musculus molossinus-derived inbred strains. Previous findings indicated that the genetic locus coding for Ly 35 antigen was closely linked to Ly 2/3 on chromosome 6 and that epitopes detected by Ly 2.1 and Ly 35.1 monoclonal antibodies (mAb) were closely associated, as shown by binding inhibition assay. In this study, we examined the blocking effects of anti-Ly 2.1 and anti-Ly 35.1 mAb on cytotoxic T-cell function of MOLF/Ei mice generated against BALB/c. MOLF/Ei cytotoxicity was blocked by Ly 35.1 mAb, but not by anti-Ly 2.1 mAb. Additional tests showed that cytotoxicity was blocked by Ly 3.1 mAb, but not Ly 3.2 or Ly 2.2 mAb. These results suggested that MOLF/Ei mice express Ly 3.1, but not Ly 2.1 antigen at a functional level, and that Ly 35.1 may be a functional epitope of Ly 2 antigen in the MOLF/Ei strain.

Animals↗
PubMed1988

Mouse monoclonal antibodies detecting disialogangliosides on mouse and human T lymphomas.

Six monoclonal antibodies (MAbs) (4 IgG3 and 2 IgM) were produced by hybridomas obtained from A/J mice immunized with EL4(C57BL/6 derived-T lymphoma). They were found to react with antigens expressed on both mouse and human T-lymphomas but not on B lymphomas or normal cells. All of these antibodies reacted with the disialoganglioside GD2, GalNAc beta I----4(NeuAc alpha 2----8NeuAc alpha 2----3)Gal beta I----4Glc-Cer, by 3 different assay systems including the immune adherence inhibition test, enzyme-linked immunosorbent assay, and enzyme immunostaining on thin-layer chromatography. The binding specificities of these MAbs to disialogangliosides differed. Four MAbs (AI-201, AI-287, AI-410, and AI-425) showed restricted specificities, detecting only GD2, whereas the other 2 (AI-245 and AI-267) had a broader specificity, recognizing GD2, GD3, and GDlb. No evidence was obtained for the presence of the antigenic epitope in glycoproteins of mouse and human tumor cells. The ganglioside content of EL4 was low in comparison with that of M14 (a human melanoma cell line).

Animals↗
PubMed1988

Different reactivities of monoclonal antibodies to ganglioside lactones.

Six murine monoclonal antibodies were found to react with ganglioside GD2 lactone as well as purified ganglioside GD2. However, the reactivities of these antibodies to various ganglioside lactones were found to differ from each other. Four antibodies only reacted with GD2 lactones, while the other two cross-reacted with lactones of other gangliosides such as GD1b and GT1b.

Animals↗
PubMed1988

Biochemical similarity of Ly-19, Ly-32, and Lyb-2 alloantigens encoded in the gene cluster on mouse chromosome 4.

Mouse lymphocyte alloantigens Ly-19 and Ly-32 are controlled by the genes tightly linked to the Lyb-2 locus on chromosome 4. Despite the similarity in mouse strain distribution patterns, Ly-19 and Ly-32 antigens which have been detected on both B- and T-cell lineages are distinct from Lyb-2 antigen whose expression is restricted to the B cells. In this report, the close linkage of these three loci was confirmed by the typings of three sets of recombinant inbred mice including BXD, CXS, and OXA. Furthermore, the biochemical characterization of these Lyb-2-linked proteins, i.e., Ly-19, Ly-32, and Lyb-2, demonstrated their similarities on a molecular level. Two polypeptides of 45,000 and 95,000 were the components of these three alloantigens. Furthermore, sequential immunoprecipitation experiments indicated that the three alloantigenic determinants were located on the same molecular components. These findings may provide insight into the complexities and functional roles of Lyb-2 gene-cluster products.

Animals↗
PubMed1988

Coupled transcription-translation of silkworm cytoplasmic polyhedrosis virus injected into oocytes of the frog, Xenopus laevis.

The cytoplasmic polyhedrosis virus of the silkworm, Bombyx mori, contains a ten-segmented, double-stranded RNA genome and five species of polypeptides, V1 (Mr 146,000), V2 (Mr 140,000), V3 (Mr 128,000)), V4 (Mr 62,000), and V5 (Mr 32,000). The virus contains an RNA-dependent RNA polymerase that transcribes the duplex genome RNA to form mRNA either in the infected animals or under appropriate conditions in vitro. We co-microinjected the virus, [alpha-32P]GTP and actinomycin D into oocytes of the frog, Xenopus laevis, and found that at least eight species of mRNA were formed in the oocytes. Virus-injected oocytes were labeled with [35S]methionine and cell extracts were treated with rabbit anti-cytoplasmic polyhedrosis virus immunoglobulin G. Analysis of the immunoprecipitates by sodium dodecyl sulfate polyacrylamide gel electrophoresis revealed that V1, V2, and V3 were produced in the virus-injected oocytes whereas V4 and V5 were not. By injecting the separated double-stranded genome segments immediately after heat-denaturation into oocytes, it was found that V1 was coded for by segment 1 with a chain length of 4.2 kilobase pairs, V2 by segment 2 or 3, whose chain lengths are both 4.0 kilobase pairs, and V3 by segment 4 with a chain length of 3.2 kilobase pairs. These results demonstrate that the Xenopus oocyte is a very useful system for the coupled transcription-translation of double-stranded RNA viruses.

Animals↗
PubMed1988

Adenosine induces dormancy in starfish blastulae.

External application of 50 micrograms ml-1 adenosine inhibits development of the starfish Asterina pectinifera at the 256-cell stage when all the embryonic cells differentiate to epithelial cells. Intracellular concentration of adenosine in the adenosine-treated embryo is 2.7 times higher than those of the normal embryo whereas the contents of ATP, ADP, AMP and adenosine 3',5'-monophosphate are the same for both embryos. Adenosine causes more than 95% reduction in the rate of protein, DNA and RNA syntheses. By returning the embryo to normal sea water, macromolecular synthesis restarts and the embryo develops to the bipinnaria stage.

Adenosine↗
PubMed1987

Effect of PGI2 on transcellular transport of fluorescein dextran through an arterial endothelial monolayer.

The effects of prostacyclin (PGI2) and stable derivatives of PGI2, such as isocarbacyclin (PGI2 deriv. (A] and isocarbacyclin methyl ester (PGI2 deriv. (B)), on junctional transport of fluorescein dextran (FD) through cultured porcine arterial endothelial cells were investigated. These PGI2S inhibited the transcellular transport dose-dependently. After the elimination of PGI2, its inhibitory effect persisted for at least 1 hr. A good correlation was found between increase of cAMP and the potency of inhibition. Increase of cAMP after PGI2 treatment seemed to be involved in the inhibition of FD transport.

1-Methyl-3-isobutylxanthine↗
PubMed1987

Sequential instillation therapy with mitomycin C and adriamycin for superficial bladder tumors.

From October 1983 to September 1985, 84 patients with superficial bladder tumor (Ta, Tl, Tis) were treated with sequential instillation of mitomycin C (MMC) and adriamycin (ADM). Doses of 20 mg MMC on day 1 and 40 mg ADM on day 2 were instilled into the bladder and retained for at least 2 h; this was repeated once a week for 5 consecutive weeks. Patients who achieved complete response (CR), were randomized and underwent prophylactic treatment taking the form of either intermittent instillation of MMC or daily oral administration of 5-fluorouracil. Of 79 evaluable patients, 72 (91%) had received prior treatment for superficial bladder tumors, 69 (87%) had high-grade tumors, and 18 (23%) had non-papillary Tis. The overall response rate was 68%, made up of CR in 43 patients (54%) and partial response (PR) in 11 (14%). Patients with either five or more tumors or tumors larger than 1 cm showed a significantly lower response rate than those with fewer than five tumors and tumors smaller than 1 cm, respectively. There was no correlation between tumor growth pattern, tumor grade and response rate, though non-papillary Tis appeared to respond better than papillary tumors. A history of prior instillation therapy or of toxicity to this treatment had no significant influence on the response rate. Although no systemic toxicity was observed, 62 patients (74%) experienced cystitis and the treatment had to be discontinued within 4 weeks in 13 of 33 cases with severe symptoms. The preliminary conclusion of prophylactic treatment was that intermittent instillation of MMC was superior to 5-FU medication in reducing the recurrence rate for at least 2 years after the treatment.

Administration, Intravesical↗
PubMed1987

Effects of bifemelane hydrochloride on cortical neuronal activity in cats.

The effects of bifemelane hydrochloride on neuronal activity in the visual cortex of the cat were studied by microiontophoretic application under methoxyflurane anesthesia. Of 195 neurons examined with both acetylcholine (ACh) and bifemelane, 67 cells (34%) were excited and 7 cells (4%) were inhibited by ACh. The effect of bifemelane was excitatory on 122 neurons (63%), inhibitory on 20 (10%) and unchanged on the rest. In 60 cells out of the above 122 neurons, bifemelane showed a similar discharge pattern to ACh with a slow onset and delayed termination. The bifemelane-induced excitation was, in 18 out of 22 cells, antagonized by atropine (30-40 nA). Also, a potentiation in bifemelane-induced discharges by physostigmine (30-50 nA) was observed in 14 of the 32 cells tested. The firing evoked by ACh (80-100 nA) was potentiated during of after the application of bifemelane (30-40 nA) in 9 out of 29 neurons, which were not excited by bifemelane alone. These results suggest that neuronal discharges produced by bifemelane are induced at least in part, through a muscarinic ACh receptor, although other mechanisms may possibly be involved.

Acetylcholine↗