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Biomedical subjects

A Kudo

Publications and source records attributed to A Kudo.

At least 109 records · Page 6Linked to original sources
PubMed1987

Changes in fluorescence energy transfer between sulfhydryl fluorescent residues during ouabain sensitive Na+,K+-ATP hydrolysis.

Na+,K+-ATPase from pig kidney was sequentially modified with two different sulfhydryl fluorescent reagents, N-[p-(2-benzimidazolyl)phenyl]maleimide (BIPM) and N-[7-dimethylamino 4-coumarinyl]maleimide (DACM). The preparation thus obtained contained 3 and 2 moles of each residue in the alpha-chain. When the BIPM residues were excited at 313 nm, ouabain sensitive decrease and increase in the fluorescence intensity at not only 365 nm (BIPM fluorescence) but also 455 nm (DACM fluorescence) were observed, which were dependent on the amounts of reaction intermediates accumulated. When DACM residues were excited directly at 390 nm, only the decrease in the fluorescence intensity was observed irrespective of the intermediates accumulated. The data suggest that at least two DACM residues which differently change their microenvironments during ouabain sensitive Na+,K+-ATPase reaction are present. One is located close enough and the other is located too far to accept the energy from BIPM residue(s) in the three dimensional structure of Na+,K+-ATPase. Addition of sodium dodecyl sulfate (SDS) remarkably inhibited the energy transfer from BIPM to DACM residues. Limited proteolysis suggested that BIPM residues are located mainly in the peptides which are assumed to contain ATP binding sites and that DACM residues are located near the phosphorylation sites.

Adenosine Triphosphate↗
PubMed1986

Trans-acting nuclear protein responsible for induction of rearranged human immunoglobulin heavy chain gene.

A complete human gamma 1 heavy chain gene (HIG1) was transferred into mouse cells by protoplast fusion. The HIG1 gene was strongly expressed in mouse myeloma cells but not in mouse fibroblasts (L cells). Nuclear extracts from myeloma cells were injected into L cell transformants containing one copy of the HIG1 gene; this triggered accurate transcription of the HIG1 gene in the transformants. The induction of HIG1 gene expression by a myeloma nuclear factor (or factors) appeared to depend on the enhancers in the heavy chain gene. Nuclear proteins prepared from cells of the B lineage could induce the transcription of HIG1 gene in the L cell transformants, while those from the cells of non-B-lineage could not. The present study shows that positive regulatory trans-acting factors are involved in the activation of the immunoglobulin heavy chain gene through its enhancers and are contained only in cells of the B lineage.

B-Lymphocytes↗
PubMed1986

Cell-type-specific and regulated expression of a human gamma 1 heavy-chain immunoglobulin gene in transgenic mice.

A functionally rearranged human gamma 1 heavy-chain immunoglobulin gene was cloned from a human plasma cell leukemia cell line, ARH-77, into the phage lambda Charon 4A. The recombinant phage DNA was introduced into fertilized mouse eggs (about 200 copies of the human gene per egg). A total of 30 mice were born and were screened for the presence of the human gamma 1 gene by dot hybridization. Two of these 30 mice had integrated one or two copies of the gene. The gamma 1 mRNAs were detected only in spleen. Levels of gamma 1 mRNA and the percentage of spleen cells producing human gamma chain increased up to 50-fold after treatment with bacterial lipopolysaccharide (a B-cell mitogen) but not with concanavalin A (a T-cell mitogen), suggesting B-cell-specific and regulated expression of the human gamma 1 heavy-chain gene. Human gamma chain-producing cells were found only in the periphery of the germinal center of the white pulp in histological sections of the spleen but not in sections of other tissues. Human gamma chains appeared to be coupled with mouse light chains to form a complete IgG molecule and were secreted into the cell supernatant. The production and secretion of endogenous immunoglobulin heavy and light chains in transgenic mice appeared to be the same as in normal mice. About one-seventh of the spleen cells that produced endogenous mouse heavy chains also produced human gamma chains, but no cells that produced only human gamma chain were observed.

Animals↗
PubMed1985

A cloned human immunoglobulin heavy chain gene with a novel direct-repeat sequence in 5' flanking region.

A rearranged human immunoglobulin gamma 1 heavy-chain gene (HIG1) was cloned from a human plasma cell leukemia cell line, ARH-77. The cloned gene possessed a unique direct repeat sequence of 84 bp in the 5' flanking region as well as an enhancer-like element in the JH-C gamma 1 intron. The latter sequence is located 1 kb downstream of 3' end of the J6 exon. The direct-repeat sequence in the 5'-flanking region contained a core-like sequence resembling that of viral enhancer elements. It is located in the intron between two leader exons. P1 nuclease mapping and exonuclease VII digestion experiments showed that most of the direct repeats are noncoding regions and spliced out from the transcript. These data suggested that HIG1 gene might have two kinds of enhancer-like elements at both sides of the V region gene. HIG1 gene has been introduced by the protoplast fusion into mouse myeloma cells (NSI and J558L cells) and mouse fibroblasts. A pSV2gpt vector containing HIG1 gene (pSV2-HIG1) was used to transform the cells. The amounts of mRNA synthesized in the transformed cells were at least 50 to 100 times larger than those in ARH-77 cells, although about one copy of HIG1 gene was present in DNA of a transformed cell. HIG1 gene was not expressed in fibroblasts, indicating that the enhancer of HIG1 gene acts in a tissue-specific manner but not in a species-specific one. The role of two kinds of enhancer-like elements in HIG1 gene is discussed in connection with the high-level expression of this gene in mouse myeloma cells.

Animals↗
PubMed1985

The antibody molecule to common acute lymphocytic leukemia (cALL) antigen used the identical or closely related VH gene segment as that of MOPC-21 immunoglobulin heavy chain.

We have cloned a rearranged immunoglobulin heavy chain variable (VH) region gene (NL-1-H-5) from the cells of a mouse hybridoma, NL-1, which produce a monoclonal antibody against the common acute lymphocytic leukemia (cALL) antigen. The DNA base sequence of NL-1-H-5 clone revealed that the VH region gene of NL-1 cells used the identical or closely related leader (L) and VH gene to those of the myeloma cell line MOPC-21. There were seven base differences, and six of them were found in the second complementary-determining hypervariable region (CDR-2). The five nucleotide differences in CDR-2 resulted in the variation of amino acid residues of positions 54, 56, 58, and 59. In particular, nucleotide changes at position 56 and 59 yielded tyrosine residues which might be involved in a part of the antibody-combining site structure for cALL antigen.

Animals↗
PubMed1984

Induction of immunoglobulin gene expression in mouse fibroblasts by cycloheximide treatment.

A complete set of a rearranged human gamma 1-heavy chain gene, HIG1, was cloned from human plasma cell leukemia line, ARH-77, and transferred into mouse cells. It was strongly expressed in mouse myeloma cells but not in mouse L cells, indicating that immunoglobulin gene expression is not species-specific but cell-specific. However, a remarkable production of human gamma 1 chain was induced in mouse L cells containing HIG1 gene when the cells were treated with cycloheximide for a short period. The role of a labile repressor molecule in the expression of the immunoglobulin gene is proposed.

Animals↗
PubMed1984

Mercury dispersion from Minamata Bay to the Yatsushiro Sea during 1975-1980.

Nearly three decades have passed since the first outbreak of Minamata disease (methyl mercury poisoning). Since then, the Japanese government has taken the position that mercury contamination is occurring only within Minamata Bay, and commercial and sport fishing has been prohibited only within the bay. However, about 30 tons of mercury has quietly been moving into the Yatsushiro Sea, although most of the mercury (150 tons) which was released (and which induced the disease) has been deposited with bed sediments within Minamata Bay. Observations from 1975 to 1980 confirm that the dispersion of the mercury from the bay into Yatsushiro Sea is imminent and that the average concentration of mercury in bed sediments has increased 315% between 1975 and 1980 in the Yatsushiro Sea.

Chemical Precipitation↗
PubMed1983

Accidental release of fluoride into experimental pond and accumulation in sediments, plants, algae, molluscs and fish.

The fate of fluoride in a simulated accidental release into an experimental pond was observed for 30 days in Grenoble, France. The components investigated were water, sediments, plants, algae, molluscs, and fish. Twenty-four hours after the release, most (99.8%) of the fluoride was distributed in the physical components (water and sediments), and the biological agents contained only 0.2% of the fluoride released. Despite an exposure to hot spots of 5000 ppm at the beginning of the accidental release, no visible toxic effects were observed on the biological components such as plants, algae, molluscs, and fish. The effects of the physical components in the defluoridation showed a significant role in the control the accidental release of fluoride in the aquatic system.

Animals↗