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K Saigo

Publications and source records attributed to K Saigo.

At least 37 records · Page 2Linked to original sources
PubMed2001

Novel taurine-containing uridine derivatives and mitochondrial human diseases.

Two novel modified uridines were identified from mammalian mitochondrial (mt) tRNAs. Mass spectrometric analysis revealed that they are modified uridines possessing a sulfonic acid group derived from taurine; 5-taurinomethyl-uridine from mt tRNAs for Trp and Leu(UUR), and 5-taurinomethyl-2-thiouridine from mt tRNAs for Lys, Gln and Glu. We have found lack of modification of these taurine-containing uridines in mutant mt tRNAs for Leu(UUR) and Lys from pathogenic cells of mitochondrial encephalomyopathies, MELAS and MERRF, respectively.

Humans↗
PubMed2001

Acute lymphoblastic leukemia accompanied by chromosomal abnormality of translocation (12;17).

This report concerns a female patient with B-precursor acute lymphoblastic leukemia with concomitant expression of CD13 and CD33. A rare chromosomal abnormality, t(2;17)(p13:q21), was detected in 70% of metaphases analyzed. A new subgroup of acute leukemia is proposed, consisting of our case and 12 reported cases with similar chromosomal abnormalities. This subgroup has a poor prognosis and a high incidence of biphenotypic characteristics.

Antigens, CD↗
PubMed2001

Clinical characteristics of B-cell lymphoma-associated hemophagocytic syndrome (B-LAHS): comparison of CD5+ with CD5- B-LAHS.

OBJECTIVE: B-cell lymphoma-associated hemophagocytic syndrome (B-LAHS) has been increasingly reported in Asia and is regarded as a variant of intravascular lymphomatosis (IVL). Recently CD5 was reported to be expressed in some cases of diffuse large cell lymphoma and IVL. We therefore examined the expression of CD5 on lymphoma cells in B-LAHS and compared the clinical and laboratory data between CD5+ and CD5- B-LAHS. METHODS: The expression of CD5 on lymphoma cells was examined using flow cytometry and immunohistochemical analysis of paraffin sections. The clinical records were reviewed to characterize clinical features. PATIENTS: Twelve patients with B-LAHS; ten men and two women, age ranging from 41 to 82 years (median, 63.5 years) were included in this study. RESULTS: B-LAHS is characterized by fever and hepatosplenomegaly without lymphadenopathy at the initial presentation. Histological examination showed hemophagocytosis and infiltration of lymphoma cells in the bone marrow, and in some cases intravascular proliferation of lymphoid cells characteristic of IVL. All patients showed increased levels of lactate dehydrogenase, C-reactive protein, ferritin and soluble interleukin-2 receptor. In eight of the twelve patients, lymphoma cells were positive for CD5. But no differences were observed in the clinical or laboratory findings between CD5+ B-LAHS and CD5- B-LAHS. CONCLUSION: No clinical differences were observed between CD5+ B-LAHS and CD5- B-LAHS. Further studies are required to elucidate the differences in pathogenesis between these two subgroups of B-LAHS.

Adult↗
PubMed2001

[All-trans retinoic acid combined with low-dose cytosine arabinoside treatment for acute myelogenous leukemia with trilineage myelodysplasia--a case report].

AML with trilineage myelodysplasia (AML/TMDS) is recognized as having of poor prognosis due to its resistance to chemotherapy in comparison with de novo AML. An AML/TMDS patient who failed to respond to ordinary induction therapy achieved complete remission with combination therapy consisting of all-trans retinoic acid (ATRA) and low-dose Ara-C. No serious toxicity was observed. ATRA combined with low-dose Ara-C could be an alternative treatment for this kind of patient.

Antimetabolites, Antineoplastic↗
PubMed2000

Structure and site-directed mutagenesis of a flavoprotein from Escherichia coli that reduces nitrocompounds: alteration of pyridine nucleotide binding by a single amino acid substitution.

The crystal structure of a major oxygen-insensitive nitroreductase (NfsA) from Escherichia coli has been solved by the molecular replacement method at 1.7-A resolution. This enzyme is a homodimeric flavoprotein with one FMN cofactor per monomer and catalyzes reduction of nitrocompounds using NADPH. The structure exhibits an alpha + beta-fold, and is comprised of a central domain and an excursion domain. The overall structure of NfsA is similar to the NADPH-dependent flavin reductase of Vibrio harveyi, despite definite difference in the spatial arrangement of residues around the putative substrate-binding site. On the basis of the crystal structure of NfsA and its alignment with the V. harveyi flavin reductase and the NADPH-dependent nitro/flavin reductase of Bacillus subtilis, residues Arg(203) and Arg(208) of the loop region between helices I and J in the vicinity of the catalytic center FMN is predicted as a determinant for NADPH binding. The R203A mutant results in a 33-fold increase in the K(m) value for NADPH indicating that the side chain of Arg(203) plays a key role in binding NADPH possibly to interact with the 2'-phosphate group.

Amino Acid Sequence↗
PubMed2000

Sensitive assay of RNA interference in Drosophila and Chinese hamster cultured cells using firefly luciferase gene as target.

A sensitive cellular assay system for RNA interference was developed using the firefly luciferase gene as target. RNA interference was noted not only in Drosophila cultured cells but Chinese hamster cells (CHO-K1) as well, although double-stranded RNA required for the latter was 2500 times more than for the former. Cognate double-stranded RNA as short as 38 bp was found to be still capable of inducing RNA interference in Drosophila cultured cells.

Animals↗
PubMed2000

Hepatitis B virus-related insertional mutagenesis implicates SERCA1 gene in the control of apoptosis.

We have used the Hepatitis B Virus DNA genome as a probe to identify genes clonally mutated in vivo, in human liver cancers. In a tumor, HBV-DNA was found to be integrated into the gene encoding Sarco/Endoplasmic Reticulum Calcium ATPase (SERCA), which pumps calcium, an important intracellular messenger for cell viability and growth, from the cytosol to the endoplasmic reticulum. The HBV X gene promoter cis-activates chimeric HBV X/SERCA1 transcripts, with splicing of SERCA1 exon 11, encoding C-terminally truncated SERCA1 proteins. Two chimeric HBV X/SERCA1 proteins accumulate in the tumor and form dimers. In vitro analyses have demonstrated that these proteins localize to the ER, determine its calcium depletion and induce cell death. We have also shown that these biological effects are related to expression of the SERCA, rather than of the viral moiety. This report involves for the first time the expression of mutated SERCA proteins in vivo in a tumor cell proliferation and in vitro in the control of cell viability. Oncogene (2000).

Aged↗
PubMed2000

Electronic interactions in a new fullerene dimer: C(122)H(4), with two methylene bridges

The isolation of a new fullerene dimer, C(122)H(4), and its structural characterization by (13)C NMR and (1)H NMR spectroscopy and by UV/vis and IR spectroscopy are reported. The structure of this dimer consists of two fullerene cages, which are directly connected through two C-C bonds and two methylene bridges. Consequently, adjacent hexagonal faces of the two fullerene cages are arranged in a face to face manner. Molecular orbital calculations indicate that the proximity of the fullerene cages results in significant through space overlap in both the HOMO and LUMO. As a consequence of this overlap, the electrochemistry of the dimer shows electronic communication with stepwise reduction of each cage.

Journal Article↗
PubMed2000

Requirements of Kettin, a giant muscle protein highly conserved in overall structure in evolution, for normal muscle function, viability, and flight activity of Drosophila.

Kettin is a giant muscle protein originally identified in insect flight muscle Z-discs. Here, we determined the entire nucleotide sequence of Drosophila melanogaster kettin, deduced the amino acid sequence of its protein product (540 kD) along with that of the Caenorhabditis elegans counterpart, and found that the overall primary structure of Kettin has been highly conserved in evolution. The main body of Drosophila Kettin consists of 35 immunoglobulin C2 domains separated by spacers. The central two thirds of spacers are constant in length and share in common two conserved motifs, putative actin binding sites. Neither fibronectin type III nor kinase domains were found. Kettin is present at the Z-disc in several muscle types. Genetic analysis showed that kettin is essential for the formation and maintenance of normal sarcomere structure of muscles and muscle tendons. Accordingly, embryos lacking kettin activity cannot hatch nor can adult flies heterozygous for the kettin mutation fly.

Amino Acid Sequence↗
PubMed2000

Phosphane Sulfide/Octacarbonyldicobalt-Catalyzed Pauson - Khand Reaction Under an Atmospheric Pressure of Carbon Monoxide.

Convenient access to cyclopentenones is provided by catalytic intra- and intermolecular Pauson - Khand reactions in the presence of octacarbonyldicobalt and tributylphosphane sulfide (see scheme). In contrast to other reactions of this type, they proceed under mild conditions (70 degrees C, 1 atm CO), and commercially available [Co(2)(CO)(8)] can be used without further purification.

Journal Article↗
PubMed2000

Involvement of pannier and u-shaped in regulation of decapentaplegic-dependent wingless expression in developing Drosophila notum.

In developing Drosophila notum, wingless expression is regulated by Decapentaplegic signaling positively and negatively so that only notal cells receiving optimal levels of Decapentaplegic signals express wingless (Sato et al., 1999b. Development 126, 1457-1466). Here, we show evidence that this Decapentaplegic-dependent regulation of notal wingless expression includes plural mechanisms, involving pannier and u-shaped. In the medial notum, Pannier and U-shaped form a complex (Haenlin et al., 1997. Genes Dev. 11, 3096-3108). The expression of pannier and u-shaped is positively regulated by Decapentaplegic signals emanating from the dorsal-most region. The Pannier/U-shaped complex serves as a repressor and a transcriptional activator, respectively, for wingless and u-shaped expression. In the more lateral region, wingless expression is up-regulated by U-shaped-unbound Pannier. wingless expression is also weakly regulated by its own signaling.

Animals↗
PubMed2000

Estimation of stem cell fractions in peripheral blood stem cell harvest by using an SE-9000 hematology analyzer.

We inquired whether stem cell fractions in peripheral blood stem cell harvest could be precisely detected by using a hematopoietic progenitor cell (HPC) counting system applied to an automated hematology analyzer, SE-9000. Although there was an apparent increase in the HPCs 20 h after storage in nondiluted conditions, samples diluted with RPMI-1640 containing 1.0 mg/ml EDTA-2K showed a relatively stable number of HPCs. There was a significant relationship between HPCs and CD34 cells (n = 75, r = 0.769). This method may represent the least expensive and most time-effective way for stem cell estimation in harvest products.

Anticoagulants↗
PubMed2000

Requirements of Lim1, a Drosophila LIM-homeobox gene, for normal leg and antennal development.

During Drosophila leg development, the distal-most compartment (pretarsus) and its immediate neighbour (tarsal segment 5) are specified by a pretarsus-specific homeobox gene, aristaless, and tarsal-segment-specific Bar homeobox genes, respectively; the pretarsus/tarsal-segment boundary is formed by antagonistic interactions between Bar and pretarsus-specific genes that include aristaless (Kojima, T., Sato, M. and Saigo, K. (2000) Development 127, 769-778). Here, we show that Drosophila Lim1, a homologue of vertebrate Lim1 encoding a LIM-homeodomain protein, is involved in pretarsus specification and boundary formation through its activation of aristaless. Ectopic expression of Lim1 caused aristaless misexpression, while aristaless expression was significantly reduced in Lim1-null mutant clones. Pretarsus Lim1 expression was negatively regulated by Bar and abolished in leg discs lacking aristaless activity, which was associated with strong Bar misexpression in the presumptive pretarsus. No Lim1 misexpression occurred upon aristaless misexpression. The concerted function of Lim1 and aristaless was required to maintain Fasciclin 2 expression in border cells and form a smooth pretarsus/tarsal-segment boundary. Lim1 was also required for femur, coxa and antennal development.

Adaptor Proteins, Signal Transducing↗
PubMed2000

Formation and specification of distal leg segments in Drosophila by dual Bar homeobox genes, BarH1 and BarH2.

Here, we show that BarH1 and BarH2, a pair of Bar homeobox genes, play essential roles in the formation and specification of the distal leg segments of Drosophila. In early third instar, juxtaposition of Bar-positive and Bar-negative tissues causes central folding that may separate future tarsal segments 2 from 3, while juxtaposition of tissues differentially expressing Bar homeobox genes at later stages gives rise to segmental boundaries of distal tarsi including the tarsus/pretarsus boundary. Tarsus/pretarsus boundary formation requires at least two different Bar functions, early antagonistic interactions with a pretarsus-specific homeobox gene, aristaless, and the subsequent induction of Fas II expression in pretarsus cells abutting tarsal segment 5. Bar homeobox genes are also required for specification of distal tarsi. Bar expression requires Distal-less but not dachshund, while early circular dachshund expression is delimited interiorly by BarH1 and BarH2.

Animals↗
PubMed2000

Transcriptional regulation of atonal required for Drosophila larval eye development by concerted action of eyes absent, sine oculis and hedgehog signaling independent of fused kinase and cubitus interruptus.

Bolwig's organ is the larval light-sensing system consisting of 12 photoreceptors and its development requires atonal activity. Here, we showed that Bolwig's organ formation and atonal expression are controlled by the concerted function of hedgehog, eyes absent and sine oculis. Bolwig's organ primordium was first detected as a cluster of about 14 Atonal-positive cells at the posterior edge of the ocular segment in embryos and hence, atonal expression may define the region from which a few Atonal-positive founder cells (future primary photoreceptor cells) are generated by lateral specification. In Bolwig's organ development, neural differentiation precedes photoreceptor specification, since Elav, a neuron-specific antigen, whose expression is under the control of atonal, is expressed in virtually all early-Atonal-positive cells prior to the establishment of founder cells. Neither Atonal expression nor Bolwig's organ formation occurred in the absence of hedgehog, eyes absent or sine oculis activity. Genetic and histochemical analyses indicated that (1) responsible Hedgehog signals derive from the ocular segment, (2) Eyes absent and Sine oculis act downstream of or in parallel with Hedgehog signaling and (3) the Hedgehog signaling pathway required for Bolwig's organ development is a new type and lacks Fused kinase and Cubitus interruptus as downstream components.

Animals↗