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Biomedical subjects

C G Kim

Publications and source records attributed to C G Kim.

At least 37 records · Page 2Linked to original sources
PubMed2000

Reporter constructs showing proper globin gene switching in cultured erythroid cell lines.

Recent advances in the study of globin gene switching in the context of complete gene locus have contributed greatly to our understanding of developmental regulation mechanism of globin gene expression. However, it is not clear yet whether the cluster is sufficient in proper gene switching when the globin genes are replaced with conventional reporter genes. Furthermore, even though erythroid-specific and ubiquitous transcription factors involved in erythroid-specific globin gene expression have been characterized and some plausible globin gene switching models have been suggested, any specific factor directly involved in globin gene switching is not yet identified. In this study, as an effort to further understand globin switching mechanism and to identify globin switching factors, we constructed reporter vectors by juxtaposing several putative regulatory elements in human beta-globin locus to conventional reporter genes and analyzed their stage-specific expression in erythroid cell lines. At the end, we demonstrated that gammabeta-type constructs, in which both gamma-type and beta-type globin reporter genes were linked in cis below beta-globin locus control region (LCR), show proper stage-specific reporter gene expression in erythroid cell lines and also recapitulate globin switching in cell hybrids.

Animals↗
PubMed2000

Induction by synaptic zinc of heat shock protein-70 in hippocampus after kainate seizures.

Following seizures, heat shock protein (HSP)-70 is induced in various brain regions. Since zinc that can induce HSP-70 in various cell systems is enriched in certain glutamatergic terminals and translocates to postsynaptic neurons with seizures, we examined the possibility that HSP-70 induction in the epileptic brain is mediated by synaptic zinc. Adult rats were injected intraperitoneally with kainate to induce seizures. Seizures were halted 3 h after the kainate administration by the injection of phenytoin. Staining of brain sections with zinc-specific fluorescent dye TFL at 24 h after the kainate injection revealed a one-to-one correlation between dense TFL fluorescence and acidophilic neuronal degeneration in the hippocampus. Subsequent staining with anti-HSP-70 antibody, however, revealed that more numerous neurons than degenerating neurons exhibited HSP-70 immunoreactivity. Most of the HSP-70(+) neurons were not stained with acid fuchsin but exhibited mild zinc fluorescence in the cytoplasm. Intraventricular injection of CaEDTA attenuated neuronal death as well as the HSP-70 induction in a dose-dependent manner. Supporting the specificity of zinc rather than calcium as the inducer of HSP-70 in neurons, exposure to zinc but not to a calcium ionophore or excitotoxins increased expression of HSP-70 mRNA and protein in cultured cortical neurons. The present results suggest that not only selective neuronal death, but also HSP-70 induction in neurons after seizures, is mediated by the translocation of endogenous synaptic zinc.

Animals↗
PubMed2000

Formation of the Japanese Carabina fauna inferred from a phylogenetic tree of mitochondrial ND5 gene sequences (Coleoptera, carabidae).

Phylogenetic analyses based on the mitochondrial ND5 gene comparisons and the geohistory of the Japanese Islands suggest that each Japanese species belonging to the subtribe Carabina has its own history for the establishment of its present habitat in the Japanese Islands. It can be roughly classified into two categories: (1) species which were derived from the ancestry that inhabited ancient Japan at the time of its split from the Eurasian Continent [ca. 15 million years ago (MYA)], followed by diversification within the Japanese Islands; and (2) species which invaded Hokkaido from the Eurasian Continent through land-bridges from Sakhalin and/or the Kuriles or from western Japan from the Korean Peninsula during the glacial era (<2 MYA).

Animals↗
PubMed2000

Pattern of morphological diversification in the Leptocarabus ground beetles (Coleoptera: Carabidae) as deduced from mitochondrial ND5 gene and nuclear 28S rDNA sequences.

Most of the mitochondrial NADH dehydrogenase subunit 5 (ND5) gene and a part of nuclear 28S ribosomal RNA gene were sequenced for 14 species of ground beetles belonging to the genus Leptocarabus. In both the ND5 and the 28S rDNA phylogenetic trees of Leptocarabus, three major lineages were recognized: (1) L. marcilhaci/L. yokoael/Leptocarabus sp. from China, (2) L. koreanus/L. truncaticollis/L. seishinensis/L. semiopacus/L. canaliculatus/L. kurilensis from the northern Eurasian continent including Korea and Hokkaido, Japan, and (3) all of the Japanese species except L. kurilensis. Clustering of the species in the trees is largely linked to their geographic distribution and does not correlate with morphological characters. The species belonging to different species groups are clustered in the same lineages, and those in the same species group are scattered among the different lineages. One of the possible interpretations of the present results would be that morphological transformations independently took place in the different lineages, sometimes with accompanying parallel morphological evolution, resulting in the occurrence of the morphological species belonging to the same species group (= type) in the different lineages.

Animals↗
PubMed2000

Differentiation within the genus Leptocarabus (excl. L. kurilensis) in the Japanese Islands as deduced from mitochondrial ND5 gene sequences (Coleoptera, Carabidae).

The phylogenetic trees have been constructed for the mitochondrial ND5 gene sequences from the Japanese Leptocarabus ground beetles, which contain 101 specimens collected from nearly the complete distribution ranges of them consisting of five morphological species, i.e., Leptocarabus procerulus, L. kumagaii, L. hiurai, L. kyushuensis and L. arboreus. On the trees, there are recognized two major lineages, each of which is further divided into two or more sublineages. The phylogenetic lines are geographically linked. Two or more species occur in a single lineage, and the same species appear in different lines. We suggest that transformation from one type of morphology to another took place in parallel in various periods of evolution of the Japanese Leptocarabus. From the phylogenetic tree and the dating from the nucleotide substitution rate and the geohistorical data it is inferred that the ancestry of all the Japanese Leptocarabus species was derived from a protoform of L. kyushuensis inhabited the ancient Japan area, followed by separation into two lineages after split of the Japanese Islands from the Eurasian Continent. They then propagated distribution to occupy their own habitat ranges, during which the morphological transformation took place in some lineages.

Animals↗
PubMed2000

Malignant papillary neoplasms of the intrahepatic bile ducts: CT and histopathologic features.

OBJECTIVE. We describe the CT and pathologic features of malignant papillary neoplasms of the intrahepatic bile ducts in 15 patients. CONCLUSION. CT is a useful technique for revealing intraductal lesions, although the findings are nonspecific and variable. When intraductal masses or nodules are seen with localized dilatation of the intrahepatic bile ducts on CT scans, malignant papillary neoplasms of the intrahepatic bile ducts should be included in the differential diagnosis.

Adult↗
PubMed2000

[Histiocytic necrotizing lymphadenitis (Kikuchi-Fujimoto's disease) accompanied by hemophagocytosis and salivary gland swelling in a patient with systemic lupus erythematosus].

After 2 years of steroid therapy that had effectively controlled her systemic lupus erythematosus, a 37-year-old woman presented with fever, erythema (face, upper chest), and low CH50. Increased oral steroid (prednisolone from 15 mg to 40 mg) and intravenous methylprednisolone (mPSL) (80 mg for 3 days) alleviated these symptoms except for the fever. Subsequently, the patient's fever worsened and leukocytopenia, abnormal liver function, lymphadenopathy (neck, axilla), and salivary gland swelling developed. Lymph node histology revealed features characteristic of Kikuchi-Fujimoto's disease (KFD). Laboratory examinations showed WBC 600/microliter, Hb 9.5 g/dl, platelets 90,000/microliter, GOT 766 IU/l, GPT 646 IU/l, LDH 4,228 IU/l, TG 1,622 mg/dl, and ferritin 6,330 ng/ml. Serum interferon gamma was also elevated (673 U/ml). Because a bone marrow smear revealed hemophagocytosis, mPSL pulse therapy (1 g for 3 days) was started for treatment of hemophagocytic syndrome. The fever promptly disappeared, and the patient's clinical symptoms resolved within 2 weeks. The abnormal laboratory data related to KFD and hemophagocytosis returned to normal within 4 weeks after the initiation of mPSL pulse therapy. We speculated that the hemophagocytosis and salivary gland involvement in this patient were also symptoms of KFD. This case indicated that corticosteroid pulse therapy is effective for KFD with serious clinical symptoms.

Adult↗
PubMed1999

Genomic organization and sequence of the mud loach (Misgurnus mizolepis) growth hormone gene: a comparative analysis of teleost growth hormone genes.

The mud loach (Misgurnus mizolepis) growth hormone (GH) gene was cloned and a comparative analysis on its genomic organization was performed. Based on Southern analysis using various kinds of restriction endonucleases, the GH gene proved to exist as a single-copy gene in the mud loach. The complete nucleotide sequences of a 5.1 kb SacI/EcoRI genomic fragment containing the mud loach GH gene and its 5' flanking sequences as well as a mud loach GH cDNA obtained by rapid amplification of a reverse transcriptase-PCR have been determined. The GH gene spans 2.0 kb from the start codon to the polyadenylation signal, and contains five exons and four introns similar to those of carps and mammals. The evolutionary relation of the mud loach GH gene, inferred by comparative analyses of gene structures and sequences in each exon and intron of representative teleost GH genes, reflects the major phylogenetic groupings of teleost.

Amino Acid Sequence↗
PubMed1999

Functional characterization of TEL/AML1 fusion protein in the regulation of human CR1 gene promoter.

The TEL/AML1 fusion gene occurs in childhood B-cell acute lymphoblastic leukemia (ALL) as a result of the translocation of human chromosome 12;21. Using reporter gene assays, we have functionally characterized TEL, AML1 and TEL/AML1 fusion proteins in the regulation of the human CR1 gene. Analysis of transcription activities showed that AML1 increased the CR1 promoter activity and that TEL repressed the basal activity of the promoter. Increased activities of the CR1 promoter by AML1 protein were reduced by the TEL protein in a concentration-dependent manner. When TEL/AML1 and AML1 proteins are present in cells at the same time, the TEL/AML1 protein inhibits the transactivation activities of AML1 protein on the human CR1 promoter even though TEL/AML1 retains the transactivation domain of AML1. A mutation analysis of the human CR1 promoter revealed that the binding sites for TEL and AML1 are necessary for the action of TEL and TEL/AML1, respectively. Thus, production of the TEL/AML1 protein by translocation of human chromosome 12;21 may contribute to leukemogenesis by the specific inhibition of AML1-dependent activation of myeloid promoters.

Binding Sites↗
PubMed1999

Transcription factor CP2 is crucial in hemoglobin synthesis during erythroid terminal differentiation in vitro.

The transcription factor CP2 was initially identified to bind to the promoter region of the murine alpha-globin gene and known to stimulate the expression of alpha-globin by increasing CP2 transcripts 3- to 5-fold during induced differentiation of mouse erythroleukemic (MEL) cells in vitro. Here, we report that this increment of CP2 expression is crucial in erythroid-specific globin gene expression and hemoglobin synthesis. When antisense CP2 was overexpressed in MEL cells, production of endogenous CP2 protein was reduced 70-80%, and significant loss of its promoter binding activity was observed. During HMBA-induced terminal differentiation of antisense CP2 expressing MEL cells, the transcription of endogenous alpha-globin gene was suppressed as expected. Moreover, both beta-globin gene expression and hemoglobin synthesis were also severely impaired, without affecting the expression of key heme enzyme genes or HMBA-induced proliferation and viability.

Acetamides↗
PubMed1999

Isolation of developmentally regulated novel genes based on sequence identity and gene expression pattern.

Based on the surmise that a variety of genes might play important roles in embryonic development and tissue differentiation, and that some of them are likely to be expressed in undifferentiated ES cells, we attempted to identify new genes from the ES cell cDNA library. The modified method of expressed sequence tags (ESTs) and the examination of the expression patterns in adult tissues and in vitro differentiated ES cells were utilized in this study. We have isolated and identified several novel cDNA clones with interesting developmental expression pattern. Among the 83 clones randomly chosen, 23 clones (27.7%) have no homology to any sequences in public databases. The rest contain limited or complete sequence homology to the previously reported mammalian genes or ESTs, yet some clones have not been previously identified in the mouse. To examine the expression profile of clones during development and differentiation, sets of slot blots were hybridized with developmental stage specific or tissue specific probes. Out of 40 novel clones tested (21 totally unknown clones and 19 unidentified clones in mouse), most of them were up- or down-regulated as differentiation proceeded, and some clones showed differentiation-stage specific expression profiles. Surprisingly, a majority of genes were also expressed in adult tissues, and some clones even revealed tissue specific expression. These results demonstrate that not only was the strategy we employed in this study quite efficient for screening novel genes, but that the information gained by such studies would also be a useful guide for further analysis of these genes. It also suggests the feasibility of this approach to explore the genomewide network of gene expression during complicated biological processes, such as embryonic development and tissue differentiation.

Amino Acid Sequence↗
PubMed1999

Characterization of a novel mouse cDNA, ES18, involved in apoptotic cell death of T-cells.

Using the modified screening approach in combination with expressed sequence tags, we have identified several novel cDNAs from mouse embryonic stem (ES) cells, whose expression is tissue-restricted and/or developmentally regulated. One of the cDNAs, ES18, is preferentially expressed in lymph node and thymus, and contains noteworthy features of transcriptional regulator. The expression of ES18 transcript was selectively regulated during the apoptosis of T-cell thymoma S49.1 induced by several stimuli. Interestingly, the ES18 transcript was differently regulated in the mutually antagonistic process, between dexamethasone- and A23187-induced cell death of T-cells. Moreover, the message level of ES18 was selectively enhanced by staurosporine, a broad protein kinase inhibitor, but not by other protein kinase inhibitors such as GF109203X and H89. In addition, ES18 transcript was induced by C2-ceramide, which is a mediator of both dexamethasone- and staurosporine-induced apoptotic signaling. We further showed that transient overexpression of ES18 in mouse T-cell lymphoma increased the apoptotic cell death. These data suggest that ES18 may be selectively involved in specific apoptotic processes in mouse T-cells.

Amino Acid Sequence↗
PubMed1999

Evolution of the carabid ground beetles.

The phylogenetic relationships of the carabid ground beetles have been estimated by analysing a large part of the ND5 gene sequences of more than 1,000 specimens consisting of the representative species and geographic races covering most of the genera and subgenera known in the world. From the phylogenetic analyses in conjunction with the mtDNA-based dating, a scenario of the establishment of the present habitats of the respective Japanese carabids has been constructed. The carabid diversification took place ca. 40 MYA as an explosive radiation of the major genera. During evolution, occasional small or single bangs also took place, sometimes accompanied by parallel morphological evolution in phylogenetically remote as well as close lineages. The existence of silent periods, in which few morphological changes took place, has been recognized during evolution. Thus, the carabid evolution is discontinuous, alternatively having a phase of rapid morphological change and a silent phase.

Animals↗
PubMed1999

Inflammatory pseudotumor of the liver in patients with recurrent pyogenic cholangitis: CT-histopathologic correlation.

PURPOSE: To correlate computed tomographic (CT) features of inflammatory pseudotumors of the liver with histopathologic results in patients with recurrent pyogenic cholangitis. MATERIALS AND METHODS: CT features of 13 cases of inflammatory hepatic pseudotumor in 10 patients with recurrent pyogenic cholangitis were reviewed. Diagnosis was made by means of surgical resection in all patients. CT scans were analyzed for the appearance of masses and ancillary findings in correlation with the histopathologic findings in each resected specimen. RESULTS: The masses were 2.0-7.0 cm (mean, 3.5 cm). At nonenhanced CT, the masses appeared as ill-defined, hypoattenuating lesions. At contrast material-enhanced CT, the masses exhibited central hypoattenuating areas with an iso- or hyperattenuating thickened periphery in four cases and a multiseptate appearance with hyperattenuating internal septa and periphery in nine cases. CT-histopathologic correlation showed that the central hypoattenuating area indicated the presence of chronic inflammatory infiltrates with foamy histiocytes, plasmacytes, and lymphocytes, while iso- or hyperattenuating areas in the periphery and internal septa of the mass represented fibroblastic proliferation. All patients had CT features of recurrent pyogenic cholangitis, such as hepatolithiasis, intrahepatic duct stricture and dilatation, common bile duct calculi, pneumobilia, or parenchymal atrophy. CONCLUSION: Although CT features are not specific, inflammatory pseudotumor should be included in the differential diagnosis in patients with recurrent pyogenic cholangitis and a hepatic mass detected at CT.

Adult↗
PubMed1998

3-Amino-5-hydroxybenzoic acid synthase, the terminal enzyme in the formation of the precursor of mC7N units in rifamycin and related antibiotics.

The biosynthesis of ansamycin antibiotics, like rifamycin B, involves formation of 3-amino-5-hydroxybenzoic acid (AHBA) by a novel variant of the shikimate pathway. AHBA then serves as the starter unit for the assembly of a polyketide which eventually links back to the amino group of AHBA to form the macrolactam ring. The terminal enzyme of AHBA formation, which catalyzes the aromatization of 5-deoxy-5-amino-3-dehydroshikimic acid, has been purified to homogeneity from Amycolatopsis mediterranei, the encoding gene has been cloned, sequenced, and overexpressed in Escherichia coli. The recombinant enzyme, a (His)6 fusion protein, as well as the native one, are dimers containing one molecule of pyridoxal phosphate per subunit. Mechanistic studies showed that the enzyme-bound pyridoxal phosphate forms a Schiff's base with the amino group of 5-deoxy-5-amino-3-dehydroshikimic acid and catalyzes both an alpha, beta-dehydration and a stereospecific 1,4-enolization of the substrate. Inactivation of the gene encoding AHBA synthase in the A. mediterranei genome results in loss of rifamycin formation; production of the antibiotic is restored when the mutant is supplemented with AHBA.

Actinobacteria↗
PubMed1998

Interaction of phospholipase C gamma 1 via its COOH-terminal SRC homology 2 domain with synaptojanin.

The role of the phospholipase C gamma 1 (PLC gamma 1) in signal transduction was investigated by characterizing its interactions with proteins that may represent components of a novel signalling pathway. A 145-kDa protein that binds SH2 domain of PLC gamma 1 was purified from rat brain. The sequence of peptide derived from the purified binding protein now identify it as synaptojanin, a nerve terminal protein that has been implicated in the endocytosis of fused synaptic vesicles and shown to be a member of the inositol polyphosphate 5-phosphatase family. We demonstrate here stable association of PLC gamma 1 with synaptojanin, a protein that not only binds carboxyl terminal SH2 domain of PLC gamma 1, but also inhibits PLC gamma 1 activity.

Amino Acid Sequence↗
PubMed1998

The effect of 2-mercapto-5-methyl-1,3,4-thiadiazole on enzymatic synthesis of cefazolin.

The effect of unreacted residual 2-mercapto-5-methyl-1,3,4-thiadiazole (MMTD), the reagent for 3-[5-methyl-1,3,4-thiadiazole-2-yl]-7-aminocephalosporanic acid (M-7-ACA) synthesis, on the enzymatic acylation of M-7-ACA by the methyl ester of 1,2,3,4-tetrazol-1-acetic acid (MeTzAA) to produce cefazolin (CEZ) was studied. In the two-step process of synthesizing CEZ from 7-aminocephalosporanic acid (7-ACA), one of the key parameters controlling the overall CEZ yield was the ratio of MMTD to 7-ACA in M-7-ACA synthesis. The increase of the ratio showed opposing effects by increasing the M-7-ACA yield in the first step, while decreasing CEZ yield in the subsequent enzymatic reaction by the inhibitory effect of the increased content of MMTD as an impurity in the M-7-ACA preparation. It was revealed that the decrease of CEZ yield in the enzymatic reaction was caused by the selective retardation of the rate of CEZ synthesis reaction by a typical competitive inhibition, while not affecting the rate of MeTzAA hydrolysis reaction. The optimum MMTD-to-7-ACA ratio rendering the highest overall CEZ yield over 7-ACA was 1.2:1.

Catalysis↗