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Biomedical subjects

N Asami

Publications and source records attributed to N Asami.

14 recordsLinked to original sources
PubMed1999

A reversibly antigen-responsive hydrogel.

Stimuli-responsive hydrogels that undergo abrupt changes in volume in response to external stimuli such as pH, temperature and solvent composition have potential applications in biomedicine and the creation of 'intelligent' materials systems, for example as media for drug delivery, separation processes and protein immobilization. Hydrogels have been reported that respond to pH, temperature, electric fields and saccharides. For some biomedical applications it would be very useful to have a material whose swelling response was dictated by a specific protein. Here we report such a material, which swells reversibly in a buffer solution in response to a specific antigen. The hydrogel was prepared by grafting the antigen and corresponding antibody to the polymer network, so that binding between the two introduces crosslinks in the network. Competitive binding of the free antigen triggers a change in gel volume owing to breaking of these non-covalent crosslinks. In addition, we show that the hydrogel displays shape-memory behaviour, and that stepwise changes in antigen concentration can induce pulsatile permeation of a protein through the network.

Animals↗
PubMed1996

Gene transduction into murine primitive hematopoietic cells with 2-gene retroviral vectors using a Transwell coculture system.

The present study aims at expressing a reporter gene in hematopoietic cells in vivo by introducing it into primitive hematopoietic cells with a 2-gene retroviral vector. Various constructs of retroviral vectors containing the human IL-2 receptor alpha chain gene (TAC) as the reporter and the neomycin phosphotransferase gene (neo) as a selectable marker were engineered, and the effectiveness of these vectors for expression of the reporter gene was evaluated after transfection into the packaging cell line GP + E86. It was found that the highest levels of reporter gene expression were attained with constructs ordered 5' long terminal repeat (LTR)-TAC-internal promoter-neo-3' LTR. In experiments investigating the expression of a reporter gene in hematopoietic cells, we used the Escherichia coli beta-galactosidase gene (lacZ) instead of TAC, because a very sensitive detection method was available for lacZ. For transduction of hematopoietic progenitors, packaging cell lines producing recombinant viruses were cultured in a Transwell hung into a Dexter-type bone marrow (BM) culture. The BM cells were selected with G418, and transferred into irradiated recipient mice. LacZ enzyme activity was detectable in the peripheral blood lymphocytes (PBL) of recipients taken 8 wk after reconstitution.

Animals↗
PubMed1995

Sequences of two porcine glutamic acid decarboxylases (65- and 67-kDa GAD).

The cDNAs encoding the porcine 65- and 67-kDa glutamic acid decarboxylases (GAD65 and GAD67, respectively) were cloned by the PCR method. The 2246-nucleotide (nt) GAD65 cDNA contained an open reading frame (ORF) coding for a protein of 585 amino acids (aa), and the 3262-nt GAD67 cDNA contained an ORF coding for a protein of 594 aa. A remarkable conservation was shown when the deduced aa sequences of porcine GAD65 and GAD67 were compared with those of other mammalian species (human, cat and rat). Porcine GAD65 is 96% identical to human and rat GAD65, and porcine GAD67 is more than 95% identical to human, cat and rat GAD67 at the aa level.

Amino Acid Sequence↗
PubMed1994

Efficient retrovirus-mediated gene transduction into murine hematopoietic stem cells and long-lasting expression using a Transwell coculture system.

The neomycin phosphotransferase (neo) gene was transduced into murine hematopoietic stem cells by culturing a recombinant retrovirus-producing cell line in a Transwell (Costar, Cambridge, MA) (bottomed with a porous membrane) hung into a Dexter-type long-term bone marrow (BM) culture. Gene transduction into stem cells retaining long-term reconstitution ability was successfully performed by using protocols of total 15 to 18 days of culture including establishment of the Dexter culture, transduction, and G418 selection. In the irradiated recipients of these cells, a large majority of the BM, thymus, and spleen cells as well as peripheral blood (PB) leukocytes were of donor origin and the neo gene was present in these organs up to 21 weeks after cell transfer. One third to two thirds of the in vitro colony-forming cells in the BM of the recipient mice were resistant to cultivation with G418. It was further found that the hematopoietic system of secondary recipients given BM cells from a primary recipient mouse was predominated by original donor-type cells. The transduced neo gene was detected in the PB, BM, thymus, and spleen cells of these secondary recipients. These results indicate that our procedure of retroviral vector-mediated gene transfer is highly effective in safely introducing a gene into pluripotent hematopoietic stem cells.

Animals↗
PubMed1993

Antibody recognition of the recombinant human nuclear antigens RNP 70 kD, SS-A, SS-B, Sm-B, and Sm-D by autoimmune sera.

Five human nuclear antigens, RNP 70 kD, SS-A, SS-B, Sm-B and Sm-D, were produced in E. coli using the expression vector pSEM. cDNAs encoding these antigens were ligated to a truncated lacZ' gene of the vector and the beta-galactosidase fusion proteins were efficiently expressed as intracellular inclusion bodies after isopropyl-beta-thiogalactopyranoside induction. The antibody reactivities of these fusion proteins were evaluated by Western blot and by ELISA employing panel sera from patients with autoimmune diseases such as systemic lupus erythematosus, Sjögren's syndrome or mixed connective tissue disease. The three fusion proteins, RNP 70 kD, SS-B, and Sm-B, showed good reactivities in both systems, whereas the other two fusion proteins, SS-A and Sm-D, showed poor and no reactivity in both systems, respectively. It can be concluded that RNP 70 kD, SS-B and Sm-B recombinant antigens are useful reagents for the differential diagnosis of the autoimmune diseases.

Autoantigens↗
PubMed1990

Antitumor activity of a derivative of mitomycin, 7-N-[2-[[2-(gamma-L-glutamylamino)ethyl]dithio]ethyl]mitomycin C (KW-2149), against murine and human tumors and a mitomycin C-resistant tumor in vitro and in vivo.

The antitumor activity of a mitomycin derivative, 7-N-[2[[2-(gamma-glutamylamino)ethyl]dithio]ethyl]mitomycin C (KW-2149), was evaluated in murine and human tumor models, including a mitomycin C (MMC)-resistant tumor in vitro and in vivo. KW-2149 showed a profound effect against i.p. inoculated P388 leukemia on both a single and an intermittent administration schedule. Against s.c. implanted colon adenocarcinoma 38 (colon 38). KW-2149 was as effective as MMC in ILS% and in tumor growth inhibition on a single-administration schedule. Both compounds were similarly effective when an intermittent schedule was used. KW-2149 showed activity against human tumor xenografts and was effective in two of four non-small-cell lung carcinomas but was not effective against three gastric adenocarcinomas on the single-administration regimen. The activity of KW-2149 against gastric adenocarcinoma was inferior to that of MMC on a single-administration schedule. However, the antitumor activity of KW-2149 was higher on an intermittent schedule than on a single-administration regimen. The antitumor activity of KW-2149 against human tumor xenografts was similar to that of MMC on an intermittent schedule, and the former drug was effective against both gastric adenocarcinomas and both non-small-cell lung carcinomas. KW-2149 was more effective than MMC against a subline of P388 leukemia that is resistant to MMC in vitro as well as in vivo.

Adenocarcinoma↗
PubMed1990

Brain metastasis from transitional cell carcinoma of the bladder--case report.

A rare case of brain metastasis from a transitional cell carcinoma (TCC) of the bladder is presented. A 66-year-old female underwent total removal of a bladder carcinoma and postoperative radiation therapy and chemotherapy. Right hemiparesis and seizures developed about 16 months later, and a solitary brain metastasis was discovered in the left Rolandic area. The tumor was totally removed and microscopic examination showed it to be TCC.

Aged↗
PubMed1990

[Moyamoya disease in fraternal twins].

The authors have reported here fraternal twins of moyamoya disease. The one has the onset at the age of two years and six months. Then he had suffered from multiple cerebral infarction and resulting in severe neurological deficits. Now he has right hemiparesis, left homonymous hemianopsia, aphasia and mental retardation. The encephalomyo synangiosis was done to the boy bilaterally at the age of five years. The other one has the onset at the age of five years and five months. He had good physical and neurological development. The Superficial temporal artery-Middle cerebral artery anastomosis and Encephalomyo synangiosis were done bilaterally. Now his development has no problems. The twins and their younger sister all have the same HLA type. The hereditary and environmental factors may be completely related to the pathogenesis of this disease.

Adult↗
PubMed1989

Expression of P-glycoprotein mRNA in human gastric tumors.

We have isolated a cDNA clone, pCA12-2, from a lambda gt11 cDNA library of an adriamycin-resistant subline of human myelogenous leukemia K562 (K562/ADM) by plaque hybridization with the 2.6 kb genomic probe of P-glycoprotein reported previously. The cDNA pCA12-2 was identified as the 3'-part of P-glycoprotein cDNA by dideoxy sequencing. By using the cDNA probe, expression of P-glycoprotein mRNA was examined in human gastric xenograft lines transplanted in nude mice and clinical samples of human gastric normal tissues and tumors. Five gastric tumor xenograft lines expressed low but significant levels of P-glycoprotein mRNA. The extent of expression was higher in some cases than that observed for R1-3, a weakly drug-resistant subline of K562. Normal gastric tissues from three patients expressed similar levels of P-glycoprotein mRNA and the extent of expression was slightly higher than that of R1-3. Two of three gastric tumor samples expressed higher levels of mRNA than normal gastric tissues. These results suggest that the intrinsic insensitivity of human gastric cancers to chemotherapy could be partly explained by the expression of P-glycoprotein.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1989

[Brain metastases from carcinomas of the digestive organs--a comparative study with those from pulmonary carcinomas].

During the past 11 years, we have experienced 7 cases of a metastatic brain tumor with the primary lesion in the digestive organs. Their clinical courses were retrospectively compared with those of 19 cases with a brain metastases from pulmonary carcinomas. Leptomeningeal carcinomatosis was found in 2 patients of the former group but none in the latter. Six out of 7 brain metastases in the former group were found to have averaged 13 months before their appearance after the diagnosis of the primary lesion. In contrast, 14 out of 19 patients in the latter group had an onset with symptoms of a brain metastasis. The average survival after intracranial surgery on the metastatic tumor was 174 days for the former group and 268 days for the latter. The prognosis of a brain metastasis from a carcinoma of the digestive organ appears to be extremely probable.

Adult↗