Search PubMed⌕ Search

Biomedical subjects

I Oishi

Publications and source records attributed to I Oishi.

At least 37 records · Page 2Linked to original sources
PubMed1999

Spatio-temporally regulated expression of receptor tyrosine kinases, mRor1, mRor2, during mouse development: implications in development and function of the nervous system.

BACKGROUND: Drosophila neurospecific receptor tyrosine kinases (RTKs), Dror and Dnrk, as well as Ror1 and Ror2 RTKs, isolated from human neuroblastoma, have been identified as a structurally related novel family of RTKs (Ror-family RTKs). Thus far, little is known about the expression and function of mammalian Ror-family RTKs. RESULTS: We have identified murine Ror-family RTKs, mRor1 and mRor2. Both mRor1 and mRor2 genes are induced upon neuronal differentiation of P19EC cells. During neuronal differentiation in vitro, the expression of mRor2 is transiently induced, although that of mRor1 increases continuously. During embryogenesis, the mRor1 gene is expressed in the developing nervous system within restricted regions and in the developing lens epithelium. The expression of mRor1 is sustained in the nervous system and is also detected in non-neuronal tissues after birth. In contrast, the expression of mRor2 is detected mainly in the developing nervous system within broader regions and declines after birth. Possible relationships of mRor1 and mRor2 genes with previously identified mutants have also been examined. CONCLUSIONS: The developmental expressions of mRor1 and mRor2, in particular in the nervous system, are differentially regulated, reflecting their expression patterns in vitro. mRor1 and mRor2 may thus play differential roles during the development of the nervous system.

Amino Acid Sequence↗
PubMed1999

Changes in testicular transferrin concentrations measured by enzyme immunoassay after FSH administration to beagle dogs.

A sensitive enzyme immunoassay (EIA) was developed for transferrin (Tf) in the canine testis, as an effective marker of Sertoli cell function. Tf was purified from male dog serum by DEAE-Affi-Gel Blue chromatography and gel filtration. Rabbits were immunized with the Tf, and anti-dog Tf antibody was purified from the rabbit serum by affinity chromatography as primary antibody for EIA. Peroxidase-conjugated goat anti-dog Tf antibody was used as the secondary antibody for microtitre plate double-antibody EIA. The EIA was applied to measurement of testicular Tf concentrations in five normal beagle dogs. All of the dogs were given five injections of 2 mg porcine pituitary FSH at 12 h intervals, and testicular biopsy was performed. The testicular tissue was used for EIA of Tf. The optimum dilutions of the primary and secondary antibodies for the standard curves of canine Tf were 1: 4000 and 1: 1000, respectively. The limits of sensitivity of our EIA were between 30 ng Tf/plate-well and 2500 ng/well. The intra- and inter-assay coefficients of variation, and the recovery rate were 8.6, 7.6 and 86.0%, respectively. Before FSH administration, the mean +/- SEM Tf concentration in the testis of normal dogs was 357 +/- 31 ng/mL. At 12 h after the final FSH administration, Tf concentrations were significantly increased (p < 0.5) when compared with values before the start of treatment. Thus, Tf in the canine testis, measured by our EIA, appears capable of serving as a marker of Sertoli cell function.

Animals↗
PubMed1999

Protein tyrosine kinase Lyn mediates apoptosis induced by topoisomerase II inhibitors in DT40 cells.

Several sets of non-receptor protein tyrosine kinases (PTK) play important roles in apoptosis induced by various extracellular stresses. Anti-cancer drugs induce cellular DNA damage and cytotoxic events, leading to apoptotic cell death. We utilized the established chicken B cell line, DT40 cells and their derived mutants, lacking the respective PTK [DT40/Syk(-), DT40/Lyn(-) and DT40/Btk(-)], to examine a role of these PTK in apoptotic processes induced by anti-cancer drugs. All anti-cancer drugs examined induced apoptosis of wild-type DT40 cells. Interestingly,DT40/Lyn(-), but not DT40/Syk(-) and DT40/Btk(-) cells, become resistant to apoptosis induced by adriamycin and etoposide, topoisomerase II (Topo II) inhibitory agents, compared to wild-type DT40 cells, as assessed by DNA fragmentation and TUNEL analyses. Ectopic expression of Fyn, another Src family member, in DT40/Lyn(-) cells restores largely the susceptibility of the cells against Topo II inhibitor-induced apoptosis. Furthermore, it was found that Topo II inhibitors activate c-Jun N-terminal kinase (JNK) slightly in both wild-type and DT40/Lyn(-) cells to similar extents. Collectively, these results suggest that Lyn is involved in Topo II inhibitor-induced apoptotic signaling in DT40 cells independent of JNK.

Animals↗
PubMed1999

Characterization of human immunodeficiency virus type 1 resistant to modified cyclodextrin sulphate (mCDS71) in vitro.

Drug resistance of human immunodeficiency virus type 1 (HIV) to modified cyclodextrin sulphate (mCDS71) has been analysed with respect to both the in vitro appearance of resistance to the compound and the mechanism of the acquisition of resistance. Resistant strains could be obtained in all three strains (NL432, KK-1 and A018) tested after serial passages in MT-4 cells with a gradual increase of the concentration of mCDS71. Cross-resistance both to mCDS71 and dextran sulphate 8000 was observed. As a result of sequencing analysis of the gp120 V3-C5 region of resistant strains, the mechanism of resistance can be explained in several ways: (i) substitution of sugar chain-binding amino acids, N and S; (ii) three to five amino acid deletion in V4 loop; and (iii) several mutations in V3 and V4 regions. The real cause of the resistance may be a combination of these three mechanisms. The results suggest that the target of mCDS71 is relatively widely distributed on the viral surface glycoprotein.

Amino Acid Sequence↗
PubMed1999

Changes in hyaluronidase, acrosin, and N-acetylhexosaminidase activities of dog sperm after incubation.

Hyaluronidase, acrosin and N-acetylhexosaminidase activities were examined in sperm collected from 12 beagle dogs and in culture medium after 0.5 hr and 7 hr of sperm incubation. The activities of the three enzymes were significantly higher at 7 hr than at 0.5 hr (P < 0.05, 0.01), and the increases were associated with sperm capacitation. It was considered that the three enzymes in the dog sperm are related to fertilization by reason of the findings of the release of these enzymes from the sperm into the medium after 7 hr of incubation.

Acrosin↗
PubMed1999

Distribution and intracellular localization of a mouse homologue of Ca2+/calmodulin-dependent protein kinase Ibeta2 in the nervous system.

Ca2+/calmodulin-dependent protein kinases (CaMKs) are believed to play important roles in the development and function of the nervous system. We report here the identification and expression of mouse CaMKIbeta (mCaMKIbeta), in particular mCaMKIbeta2, an isoform of mCaMKIbeta. During embryogenesis, the mCaMKIbeta2 gene is expressed mainly in the nervous system, including brain, spinal cord, trigeminal ganglion, and retina. Within the CNS, the expression of mCaMKIbeta2 is detected in the mantle zone, but not in the ventricular zone, suggesting its possible involvement in the differentiation of neurons. In the adult brain, mCaMKIbeta2 transcripts are detected at high levels in the anterior olfactory nuclei, piriform cortex, septal nuclei, bed nuclei of the stria terminalis, hippocampal pyramidal cells, dentate granule cells, amygdala, hypothalamic nuclei, parabrachial nucleus, and nucleus of the solitary tract. The distinct gene expression pattern suggests that mCaMKIbeta2 may also be involved in different mature neuronal functions from other CaMKs. In addition, mCaMKI/beta2 proteins are localized to the cytoplasm and nuclei, but not to nucleoli, suggesting that mCaMKIbeta2 proteins might be involved in the cytoplasmic and nuclear signal transduction of the nervous system.

Amino Acid Sequence↗
PubMed1998

A novel Drosophila nuclear protein serine/threonine kinase expressed in the germline during its establishment.

Nuclear protein kinases are believed to play important roles in regulating gene expression. We report here the identification and developmental expression of Dmnk (Drosophila maternal nuclear kinase), a Drosophila gene encoding a putative nuclear protein serine/threonine kinase with no apparent homology to previously identified protein kinases and located at 38B on the second chromosome. Dmnk mRNAs are transcribed in nurse cells and are subsequently localized in the anterior of oocytes during oogenesis, in a manner similar to several maternal transcripts regulating oogenesis and early embryogenesis. At early cleavage-stages Dmnk transcripts are transiently present throughout the embryo, but become restricted to the posterior pole and then to the newly-formed primordial germ cells (pole cells) by the blastoderm stage. The transcripts are sustained in the pole cells during gastrulation until they pass through the midgut pocket wall into the body cavity. Immunostaining with specific antibodies revealed that Dmnk proteins are localized to the nuclei in a speckled pattern. Dmnk proteins become detectable in both somatic and germ line cell nuclei upon their arrival at the periplasm of the syncytial embryo, but then disappear from the somatic cell nuclei. Consistent with mRNA expression, Dmnk proteins in pole cell nuclei are sustained during gastrulation. Taken together, Dmnk represents a novel class of nuclear protein kinases and the dynamic expression of Dmnk suggests a role in germ line establishment. The results are discussed in the light of recent findings concerning germ line establishment in Caenorhabditis and Drosophila.

Alternative Splicing↗
PubMed1998

Neurite outgrowth-promoting factors in extracts of denervated chick skeletal muscle.

1. An extract of denervated skeletal muscle contained activity for promotion of neurite outgrowth from telencephalic neurons, as well as that from neurons in the spinal cord. A factor responsible for the activity was characterized in cultures of dissociated neurons. 2. The factor acted on neurons only when they were attached to the surface of culture dishes. Since treatments with proteases and lectins reduced the outgrowth-promoting activity, the factor was thought to be a glycoprotein. 3. Among the monoclonal antibodies raised against the partially purified extract, five antibodies were found to inhibit the activity for spinal and telencephalic neurons. The most potent antibody, 4D2a, recognized mainly a 63-kD protein and other minor proteins in the extract. Although the 63-kD protein was confirmed to be chick serum albumin by analysis of amino acid sequence, the purified albumin exhibited no activity. 4. From these observations, the factor was found to be a glycoprotein recognized by the neutralizing antibody as one of the minor components of the extract. This factor exhibits its activity in a substrate-bound form but not in a diffusible one.

Amino Acid Sequence↗
PubMed1998

Anti-HIV-1 activity of herbs in Labiatae.

The anti-HIV-1 activity of aromatic herbs in Labiatae was evaluated in vitro. Forty five extract from among 51 samples obtained from 46 herb species showed significant inhibitory effects against HIV-1 induced cytopathogenicity in MT-4 cells. In particular, the aqueous extracts of Melissa officinalis, a family of Mentha x piperita "grapefruit mint," Mentha x piperita var. crispa, Ocimum basilicum cv "cinnamon," Perilla frutescens var. crispa f. viridis, Prunella vulgaris subsp. asiatica and Satureja montana showed potent anti-HIV-1 activity (with an ED of 16 microg/ml). The active components in the extract samples were found to be water-soluble polar substances, not nonpolar compounds such as essential oils. In addition, these aqueous extracts inhibited giant cell formation in co-culture of Molt-4 cells with and without HIV-1 infection and showed inhibitory activity against HIV-1 reverse transcriptase.

Anti-HIV Agents↗
PubMed1997

A novel Drosophila receptor tyrosine kinase expressed specifically in the nervous system. Unique structural features and implication in developmental signaling.

We report the identification and characterization of Dnrk (Drosophila neurospecific receptor kinase), a Drosophila gene encoding a putative receptor tyrosine kinase (RTK) highly related to the Trk and Ror families of RTKs. During Drosophila embryogenesis, the Dnrk gene is expressed specifically in the developing nervous system. The Dnrk protein possesses two conserved cysteine-containing domains and a kringle domain within its extracellular domain, resembling those observed in Ror family RTKs (Ror1, Ror2, and a Drosophila Ror, Dror). This protein contains the catalytic tyrosine kinase (TK) domain with two putative ATP-binding motifs, resembling those observed in another Drosophila RTK (Dtrk) that mediates homophilic cell adhesion. The TK domain of Dnrk, expressed in bacteria or mammalian cells, exhibits apparent autophosphorylation activities in vitro. The TK domain lacking the distal ATP-binding motif also exhibits autophosphorylation activity, yet to a lesser extent. In addition to its TK activity, there are several putative tyrosine-containing motifs that upon phosphorylation may interact with Src homology 2 regions of other signaling molecules. Collectively, these results suggest that Dnrk may play an important role in neural development during Drosophila embryogenesis.

Amino Acid Sequence↗
PubMed1997

Identification of a novel Drosophila protein kinase highly homologous to protein kinase N (PKN).

We identified a novel Drosophila gene, Dpkn (Drosophila protein kinase related to PKN), encoding a putative protein serine/threonine kinase. Although the cDNA obtained was incomplete at its 5'-terminal region, the deduced amino acid sequence of its kinase domain exhibits a high degree of similarity to protein kinase N (PKN), which has a kinase domain related to protein kinase C (PKC) and leucine zipper-like sequences in the amino terminal region. Expression of Dpkn was observed throughout Drosophila development, although its expression level decreased at later stages of embryogenesis. The expression of Dpkn is first detected in the newly formed mesodermal cell layer and is then restricted to the developing somatic musculature, indicating a possible role of Dpkn in the development of somatic muscles in Drosophila.

Amino Acid Sequence↗
PubMed1997

DNA damage-induced apoptosis and Ice gene induction in mitogenically activated T lymphocytes require IRF-1.

Lymphocytes are highly sensitive to DNA damage-induced apoptosis. In thymocytes, the tumor suppressor p53 has been shown to be required for this type of apoptosis. However an as yet unknown, p53-independent pathway(s) appears to mediate the same event in mitogenically activated mature T lymphocytes. By using mice with a null mutation in the IRF-1 gene, we revealed that DNA damage-induced apoptosis in the latter cell type is dependent on the anti-oncogenic transcription factor interferon regulatory factor-1 (IRF-1). Thus two different anti-oncogenic transcription factors, p53 and IRF-1, are required for distinct apoptotic pathways in T lymphocytes. Furthermore, we found that mitogen induction of the interleukin-1 beta-converting enzyme (Ice) gene, a mammalian homolog of the Caenorhabditis elegans cell death gene ced-3, is also IRF-1-dependent. An IRF-1 binding sequence was identified in the 5' flanking region of the Ice gene. In addition, ectopic overexpression of IRF-1 results in the activation of the endogenous Ice gene and enhances the sensitivity of cells to radiation-induced apoptosis. Thus, induction of Ice gene may be involved in IRF-1 dependent DNA damage-induced apoptosis in activated mature T lymphocytes.

Animals↗
PubMed1996

Reverse transcription-polymerase chain reaction detection and sequence analysis of small round-structured viruses in Japan.

Between 1985 and 1995, mass outbreaks of acute gastroenteritis caused by small round-structured virus (SRSV), occurred in eight prefectures in Japan. Fecal samples from 59 patients ill during these outbreaks were recently examined in our laboratory by electron microscopy (EM) and by reverse transcription-polymerase chain reaction (RT-PCR). For RT-PCR, we prepared two sets of primers, a set corresponding to the polymerase region of open reading frame 1 (ORF-1) and a set corresponding to the capsid region of ORF-2 of Norwalk virus (NV). The SRSV nucleic acid detection rate with these primers was more than double that achieved with EM. Most samples found by EM to contain virus particles were also positive by PCR. When the two sets of primers were used separately, the virus detection rate differed depending on the primer used, suggesting that the viral strains examined were not genetically not homogeneous. We then selected nine strains of the virus, cloned their PCR products and analyzed their base sequences. The base sequences of these strains were compared with those of reference strains including prototype NV and Snow Mountain agent (SMA). This comparison yielded the following findings: (1) SRSVs that cause mass outbreaks of gastroenteritis in Japan are genetically variable; (2) SRSV strains that are genetically similar to SMA and SRSV-OTH 25/89/J(OTH25) are dominant in Japan, but strains similar to NV are also present in this country; and (3) a strain (MI1/94) which is genetically identical to Southampton virus (SHV) was detected. Detection of SRSV using sensitive RT-PCR and analysis of the sequences of the amplification products seems to provide a useful means of studying the molecular epidemiology of SRSV.

Adult↗
PubMed1996

Sequence conservation and expression of the gene encoding the outer capsid glycoprotein among human group C rotaviruses of global distribution.

Group C rotaviruses have been identified recently from fecal samples of children with diarrhea in the United States. Using reverse transcriptasepolymerase chain reaction and sequence analysis, we sequenced gene 8s encoding VP7 from two U.S. strains (RI-1 and RI-2), and eight other strains isolated from patients on four continents, and compared these with the sequences of four published strains. The gene 8s of the 14 strains were remarkably conserved in size and in predicted primary and secondary structures. When the sequences of the human VP7s were compared with that of the prototype porcine Cowden strain, six regions were found variable in both deduced primary and predicted secondary structures, four of which were predicted to be hydrophilic and might determine serotype specificity. Gene 8 of the human S-1 strain was further characterized by expression in recombinant baculoviruses. The expressed product was immunogenic but failed to elicit neutralizing antibodies. Our sequence analysis indicates that all the human strains characterized to date belong to a single G genotype, which may constitute a single G serotype, pending further antigenic analysis. Whether the human strains and the Cowden strain are the same serotype remains to be determined.

Adult↗
PubMed1995

Identification of a member of the MAPKKK family as a potential mediator of TGF-beta signal transduction.

The mitogen-activated protein kinase (MAPK) pathway is a conserved eukaryotic signaling module that converts receptor signals into various outputs. MAPK is activated through phosphorylation by MAPK kinase (MAPKK), which is first activated by MAPKK kinase (MAPKKK). A genetic selection based on a MAPK pathway in yeast was used to identify a mouse protein kinase (TAK1) distinct from other members of the MAPKKK family. TAK1 was shown to participate in regulation of transcription by transforming growth factor-beta (TGF-beta). Furthermore, kinase activity of TAK1 was stimulated in response to TGF-beta and bone morphogenetic protein. These results suggest that TAK1 functions as a mediator in the signaling pathway of TGF-beta superfamily members.

Amino Acid Sequence↗
PubMed1995

An IRF-1-dependent pathway of DNA damage-induced apoptosis in mitogen-activated T lymphocytes.

Lymphocytes are particularly susceptible to DNA damage-induced apoptosis, a response which may serve as a form of 'altruistic suicide' to counter their intrinsic high potential for mutation and clonal expansion. The tumour suppressor p53 has been shown to regulate this type of apoptosis in thymocytes, but an as yet unknown, p53-independent pathway(s) appears to mediate the same event in mitogen-activated mature T lymphocytes. Here we show DNA damage-induced apoptosis in these T lymphocytes is dependent on the antioncogenic transcription factor interferon regulatory factor (IRF)-1. Thus two different anti-onco-genic transcription factors, p53 and IRF-1, are required for distinct apoptotic pathways in T lymphocytes. We also show that mitogen induction of the interleukin-1 beta converting enzyme (ICE) gene, a mammalian homologue of the Caenorhabditis elegans cell death gene ced-3, is IRF-1-dependent. Ectopic overexpression of IRF-1 results in the activation of the endogenous gene for ICE and enhances the sensitivity of cells to radiation-induced apoptosis.

Animals↗
PubMed1995

Nucleotide sequence analysis of recent epidemic strains of enterovirus 70.

Nucleotide sequences of the genome of enterovirus 70 (EV70) isolated in Osaka in 1993 were determined, and compared with those of the past epidemic strains. Nucleotide substitution rates in 332 bp, 174 bp, and 178 bp of the genes encoding viral protein (VP)1, VP2, or VP3 were 9.0, 7.5, and 5.6% between Kumoi-2/93 and J670/71, respectively. Likewise, the putative amino acid substitution rates were 1.8, 0, and 0%. It seems that the epidemic strains of EV70 in Japan have been evolving at a constant high nucleotide substitution rate but almost all the substitutions were synonymous.

Aged↗