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Biomedical subjects

H Kamada

Publications and source records attributed to H Kamada.

At least 145 records · Page 8Linked to original sources
PubMed1995

A male-associated DNA sequence in a dioecious plant, Cannabis sativa L.

Male-associated DNA sequences were analyzed in a dioecious plant, Cannabis sativa L. (family: Moraceae), which is known to have sex chromosomes. DNA was isolated from male and female plants and subjected to random amplification of polymorphic DNA. Two out of 15 primers yielded fragments of 500 and 730 bp which were detected in all male plants but not in any of the female plants tested. These two DNA fragments were cloned and used as probes in gel blot analysis of genomic DNA. When the male and female DNAs were allowed to hybridize with the 500-bp probe, no differences in patterns were observed between male and female plants. By contrast, when these DNAs were allowed to hybridize with the 730-bp probe, much more intense bands specific to male plants were detected, in addition to less intense bands that were common to both sexes. The 730-bp DNA fragment was named MADC1 (male-associated DNA sequence in Cannabis sativa). The sequence of MADC1 did not include a long open reading frame and it exhibited no significant similarity to previously reported sequences.

Base Sequence↗
PubMed1994

Ascorbic acid radical, superoxide, and hydroxyl radical are detected in reperfusion injury of rat liver using electron spin resonance spectroscopy.

Using electron spin resonance (ESR) spectroscopy, we examined whether reactive oxygen intermediates (ROIs) are produced after reperfusion of isolated, perfused rat livers subjected to global ischemia (10, 30, 60, and 90 min of ischemia). A few drops of effluent (200 microliters) flowed from reperfused liver was mixed immediately with 5,5-dimethyl-1-pyrroline-N-oxide (DMPO, final concentration 1 M), and ESR measurements were then performed. Immediately after reperfusion, a small amount of ascorbic acid radical and DMPO-OOH, which was formed by the reaction of superoxide with DMPO, was detected. The amount of ascorbic acid radical peaked immediately after reperfusion, but became hardly detectable at 6 min after reperfusion, irrespective of the period of ischemia. Six minutes after reperfusion, not only DMPO-OOH but also DMPO-OH, which was formed by the reaction of hydroxyl radical with DMPO, was detected. Thereafter, DMPO-OOH and DMPO-OH gradually declined and became hardly detectable at 40 min after reperfusion. In accordance with the duration of ischemia, the concentrations of DMPO-OOH and DMPO-OH were highest after 60 min of ischemia, and then after 30, 90, and 10 min of ischemia in decreasing order. These results directly demonstrate that the production of ROIs occurs at an early stage of reperfusion in ischemic liver and that the amount of ROI production is closely related to the duration of ischemia.

Animals↗
PubMed1994

The model of arthritis induced by superantigen in mice.

Subcutaneous injection of Staphylococcal enterotoxin B (SEB) produced by Staphylococcus aureus, caused severe arthritis in DBA/1J mice which had been previously immunized with bovine type II collagen. The severity of this arthritis was dose dependent and prolonged joint inflammation with erosion of bone was observed. Anti- type II collage antibodies were detected in the serum of arthritic mice. Effector T cells against type II collagen were also detected by means of delayed type hypersensitivity in the skin. Moreover, a significant decrease in the ratio between T cells and B cells and an increase in the ratio between CD4+ cells and CD8+ cells was observed in spleen cells from arthritic mice. Prednisolone suppresses the induction and development of clinical signs of arthritis in mice. This evidence suggests that this experimental arthritis model may provide a means to examine the role of superantigens and the efficacy of pharmacological agents for the treatment of rheumatoid arthritis.

Animals↗
PubMed1994

Characterization of two cDNAs that encode MAP kinase homologues in Arabidopsis thaliana and analysis of the possible role of auxin in activating such kinase activities in cultured cells.

Two cDNA clones, cATMPK1 and cATMPK2, encoding MAP kinases (mitogen-activated protein kinases) have been cloned from Arabidopsis thaliana and their nucleotide sequences have been determined. Putative proteins encoded by ATMPK1 and ATMPK2 genes, designated ATMPK1 and ATMPK2, contain 370 and 376 amino acid residues, respectively, and are 88.7% identical at the amino acid sequence level. ATMPK1 and ATMPK2 exhibit significant similarity to rat ERK2 (49%) and Xenopus MAP kinase (50%). The amino acid residues corresponding to the sites of phosphorylation (Thr-Glu-Tyr) that are involved in the activation of MAP kinases are conserved in ATMPK1 and ATMPK2. Northern blot analysis indicates that the ATMPK1 and ATMPK2 mRNAs are significantly present in all the organs except seeds. Genomic Southern blot analysis suggests that there are a few additional genes that are related to ATMPK1 and ATMPK2 in the Arabidopsis genome. Purified Xenopus MAP kinase kinase (MAPK kinase) phosphorylates ATMPK1 and ATMPK2 proteins that have been expressed in Escherichia coli, activating these enzymes. A rapid and transient activation of 46-kDa protein kinase activity that phosphorylated myelin basic protein (MBP) was detected when auxin-starved tobacco BY-2 cells were treated with synthetic auxin, 2,4-dichlorophenoxyacetic acid (2,4-D). Protein kinase activities which phosphorylated the recombinant ATMPK2 protein also increased rapidly after auxin treatment in the auxin-starved BY-2 cells. These results suggest that auxin may function as an activator of plant MAP kinase homologues, as do various mitogens in animal systems.

2,4-Dichlorophenoxyacetic Acid↗
PubMed1993

ATMPKs: a gene family of plant MAP kinases in Arabidopsis thaliana.

We previously reported two cDNAs for MAP kinases (cATMPK1 and cATMPK2) from a dicot plant, Arabidopsis thaliana. We describe here the cloning and characterization of five additional cDNAs encoding novel MAP kinases in Arabidopsis, cATMPK3, cATMPK4, cATMPK5, cATMPK6, and cATMPK7. The amino acid residues corresponding to the sites of phosphorylation (Thr-Glu-Tyr) that are involved in the activation of animal MAP kinases are conserved in all the seven putative ATMPK proteins. Genes for MAP kinases in Arabidopsis constitute a family that contains more than seven members. Sequence analysis suggests that there are at least three subfamilies in the family of Arabidopsis genes for MAP kinases.

Amino Acid Sequence↗
PubMed1993

Copper-metallothionein distribution in the liver of Long-Evans cinnamon rats: studies on immunohistochemical staining, metal determination, gel filtration and electron spin resonance spectroscopy.

Distribution of metallothionein (MT) and copper ion (Cu) in the liver of LEC (Long-Evans Cinnamon) rats was investigated to examine the relationship between Cu-MT induction and the development of hepatitis followed by hepatocellular carcinomas. Immunohistochemical studies on MT in the liver of LEC rats indicated that MT is accumulated in nuclei and cytosols. Both MT and Cu, estimated by radioimmunoassay and flameless atomic absorption spectrometry, respectively, in subcellular fractions of the liver were found to be concentrated highest in cytosols, followed by nuclei, mitochondria and microsomal fractions. Gel-filtration (Sephadex G-75) studies demonstrated that MT is induced as the Cu-MT form. Furthermore, the Cu-MT fragment purified by the gel-filtration contains the Cu(I)-MT form, as demonstrated by ESR (electron spin resonance) measurements at 77K. These results will be important for understanding the development of hepatitis in LEC rats.

Animals↗
PubMed1993

Cloning and characterization of two cDNAs encoding casein kinase II catalytic subunits in Arabidopsis thaliana.

Two cDNA clones, ATCKA1 and ATCKA2, encoding casein kinase II (CKII) catalytic subunits, were cloned from Arabidopsis thaliana and their nucleotide sequences were determined. Both cDNAs contain 999 bp open reading frames and are 94% identical on the amino acid sequence level. The deduced amino acid sequences of ATCKA1 and ATCKA2 are very similar to that of the human CKII catalytic alpha subunit (72% homology). Northern blot analysis indicates that the ATCKA1 and ATCKA2 mRNAs are present in all plant organs, but that ATCKA1 transcript levels are quite low compared to those of ATCKA2. Genomic Southern blot analysis suggests that there are at least three CKII genes in the A. thaliana genome. We expressed the ATCKA1 and ATCKA2 cDNAs in Escherichia coli using a pET vector derivative and analyzed the expressed protein in vitro. The expressed ATCKA1 protein phosphorylated casein using either ATP or GTP. This activity was inhibited by heparin, indicating that the expressed protein has activity similar to those reported for animal and yeast CKII.

Amino Acid Sequence↗
PubMed1993

cDNA cloning of ECP40, an embryogenic-cell protein in carrot, and its expression during somatic and zygotic embryogenesis.

A cDNA of 1.2 kb was isolated from a cDNA library of embryogenic cells of carrot (Daucus carota L.) by use of nucleotide sequences that encode two internal amino-acid sequences of ECP40 (an embryogenic-cell protein with a relative molecular mass of 40,000). A genomic Southern blot using the cDNA as probe suggested that there are at least two genes for ECP40 in the carrot genome. The cDNA encoded an open reading frame of 306 amino acids, and the deduced amino-acid sequence was found to share two motifs, namely SSSSSSEDDGXGGRRKKGXXXKIKEKLXGG and EKKXXXDKIKXKLPG, with rab16 protein from rice and dehydrins from barley and maize. The level of expression of these proteins has been reported to be high during late embryogenesis and to be induced by a plant hormone, ABA. Accumulation of ECP40-specific transcripts started 18 days after flowering and continued until maturation of seeds, but the levels decreased within 24 h after imbibition. ECP40 and its mRNAs were detected in the endosperm and zygotic embryos of mature seeds by immunohistochemistry and in situ hybridization. Exogenous application of 0.1 mM ABA to carrot seedlings did not induce expression of the gene for ECP40, while drought treatment induced the accumulation of low levels of the mRNAs. During somatic embryogenesis, the mRNAs were found at high levels in embryogenic cells and at low levels in somatic embryos at the torpedo stage. Immunohistochemical analysis and in situ hybridization showed that both ECP40 and its transcripts were preferentially localized in the peripheral cells of the clusters of embryogenic cells. In somatic embryos, application of ABA resulted in increases in levels of mRNAs for ECP40 up to the levels in embryogenic cells, but no such increases were observed in ABA-treated embryogenic cells. The pattern of expression of the gene for ECP40 during somatic embryogenesis was basically the same as that of ECP31, another ABA-regulable embryogenic-cell protein of carrot, the presence of which has been correlated with the embryogenic competence of cultured cells (T. Kiyosue, S. Satoh, H. Kamada and H. Harada, Plant Physiol 95 (1991) 1077-1083). The various results together imply that a group of ABA-inducible genes is expressed in these embryogenic cells.

Amino Acid Sequence↗