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B Cho

Publications and source records attributed to B Cho.

9 recordsLinked to original sources
PubMed1998

Acute lymphoblastic leukemia with maturation--a new entity with clinical significance.

The diagnosis of 'ALL with maturation' (ALLm) is proposed. One hundred and one patients with untreated ALL were entered into this study. The diagnosis of ALLm was made when more than 20% of all nucleated elements in the bone marrow showed maturation beyond prolymphocytes by light microscopic examination. The mature-appearing leukemic cells showed the same immunophenotype to remaining lymphoblasts. The number of ALLm cases was 19 (18.8%). The mean age at presentation of ALLm was 29 +/- 18, older than that of 18 +/- 16 of the remaining typical ALL (ALLt) (P = 0.015). Remission was induced with daunorubicin, vincristine, prednisone and L-asparaginase. Only two of 19 ALLm patients achieved CR after 4 weeks induction chemotherapy. In contrast, 57 of 82 (69.5%) ALLt patients achieved CR after the same induction chemotherapy. There was no significant difference in immunophenotype of ALLm compared with ALLt. Labeling index of DNA topoisomerase IIalpha (TopoLI) was studied by immunohistochemistry. Initial TopoLI of ALLm (221 +/- 147) was much lower than that of ALLt (609 +/- 262, P = 0.005). Furthermore, the remaining leukemic cells after chemotherapy were not labeled with anti-DNA topoisomerase IIalpha. The P53 protein was expressed in nine of 18 ALLm cases (50.0%) and P-glycoprotein was not expressed in ALLm cases. Twelve of 19 ALLm cases were studied for carrying bcr/abl fusion by karyotyping and/or fluorescent in situ hybridization. Only two cases revealed bcr/abl fusion. In conclusion, ALLm is a separate entity of ALL which has a very poor clinical course and is independent of other prognostic factors. The morphologically mature leukemic cells are in resting GO phase.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1997

Interacting RNA species identified by combinatorial selection.

RNA molecules were selected from a random sequence library for their ability to bind to an RNA stem-loop target. Oligonucleotides with extensive Watson-Crick complementarity to the RNA ligand were selected against by inclusion of a blocking oligodeoxynucleotide in the binding phase of the selection protocol. After 18 generations of SELEX (systematic evolution of ligands by exponential enrichment) a single RNA family was predominant in the binding population. The winning aptamer RNA bound the target RNA with an apparent Kd = 70 nM. Structural mapping and Fe(II)-EDTA protection indicated that the target RNA interacted with small unpaired loops in the aptamer structure.

Base Composition↗
PubMed1996

RNA libraries and RNA recognition.

Random RNA libraries, consisting of > 10(13) unique sequences, contain molecules capable of specifically binding small molecule and protein ligands by noncovalent interaction. Successive steps of affinity purification and amplification allow the propagation and eventual isolation of specific binding molecules, called aptamers. Although protein- and small-molecule-binding aptamers have been characterized previously, selection of RNA aptamers capable of binding nucleic acids has previously yielded only molecules capable of Watson-Crick base pairing to the nucleic acid ligand used for selection. On the other hand, it is known from studies on catalytic and other RNAs that both inter- and intramolecular RNA-RNA interaction can occur by non-Watson-Crick means. We have therefore incorporated a strategy to obviate the possibility of Watson-Crick interaction into a selection scheme for the isolation of RNA-recognizing aptamers. The aptamers so isolated do not show extensive Watson-Crick complementarity with the RNA ligand used for the selection, thereby validating the selection strategy. Curiously, all of the aptamers characterized contain several oligo-G stretches bounded by U residues. This sequence motif, which occurs as DNA in telomeres (chromosome ends) may therefore be a general RNA-RNA interaction motif. An additional sequence motif is apparently superimposed on this background structure.

Bacillus subtilis↗
PubMed1994

The carboxy-terminal serine 392 phosphorylation site of human p53 is not required for wild-type activities.

Wild-type p53 functions in the G1 DNA damage checkpoint pathway by activating gene transcription and preventing cell cycle progression. Others reported that mutation of the serine 386 codon in mouse p53 abolished its ability to suppress growth. Serine 386 of murine p53 and the homologous residue of human p53, serine 392, are phosphorylated in vivo and can be phosphorylated in vitro by casein kinase II (CKII). We constructed mutants that changed serine 392 of human p53 to alanine (p53-S392A) or aspartic acid (p53-S392D); cotransfection of both these mutants with a reporter gene carrying a p53-responsive element into the p53-null Saos-2 cell line activated transcription as well as did wild-type p53. Furthermore, both mutants blocked cell cycle progression after transient transfection in these cells. A stable derivative of the T98G human glioblastoma cell line was established that expressed p53-S392A in response to dexamethasone. Overexpression of this mutant activated transcription of the endogenous waf1 (also called cip1) and mdm2 genes to the same extent as wild-type p53 and also produced growth arrest. Finally, p53-S392A and p53-S392D suppressed foci formation by activated ras and adenovirus E1A oncogenes as efficiently as did wild-type p53. Thus, unlike mutants that altered the serine 15 phosphorylation site, elimination of the serine 392 phosphorylation site had no discernible effect on p53 function. We conclude that neither phosphorylation nor RNA attachment to serine 392 are required for human p53's ability to suppress cell growth or to activate transcription in vivo.

Adenovirus E1A Proteins↗
PubMed1990

Relative tumor initiating activity of benzo[a]fluoranthene, benzo[b]fluoranthene, naphtho[1,2-b]fluoranthene and naphtho[2,1-a]fluoranthene on mouse skin.

The tumor-initiating activities of benzo[a]fluoranthene (BaF), benzo[b]fluoranthene (BbF), naphtho[1,2-b]fluoranthene (NbF) and naphtho[2,1-a]fluoranthene (NaF) were evaluated on the skin of female CD-1 mice. Each of these polycyclic aromatic hydrocarbons was assayed at total initiation doses of 1.0 and 4.0 mumol/mouse. These hydrocarbons were applied in 10 subdoses administered every other day. Promotion commenced 10 days after the last initiator dose and consisted of thrice weekly application of 2.5 micrograms of tetradecanoylphorbol acetate for 20 weeks. BbF was the most potent tumor initiator inducing a 100% incidence of tumor-bearing mice with an average of 8.5 tumors per mouse at a total initiator dose of 1.0 mumol. NaF was slightly more active as a tumor initiator than either NbF or BaF. NaF induced a 90% incidence of tumor-bearing mice with an average of 5.9 tumors per mouse at a total initiator dose of 1.0 mumol. BaF and NbF at a total initiator dose of 4.0 mumol exhibited similar tumor-initiating activity with both inducing a 90% incidence of tumor-bearing mice with an average of 4.3 and 6.6 tumors per mouse, respectively. However, at a total initiator dose of 1.0 mumol, BaF and NbF induced a 95% and 65% incidence of tumor-bearing mice with an average of 3.3 and 2.5 tumors per mouse, respectively.

Animals↗
PubMed1987

Detection of intracavitary masses on gated scans: a phantom study.

A series of 1.5, 2.0 and 3.0 cm diameter paraffin balls were placed on a 3 cm tether within a simulated left ventricular balloon phantom to determine the maximal balloon volume that permitted identification of the lesion. When images were recorded with the phantom stationary, the lesions could be detected at 100, 280 and 360 ml volumes, respectively. When the phantom was set in motion with a fixed 80 ml stroke volume, the lesions were detected at 120, 320 and 360 ml, respectively. These findings suggest that gating does not decrease lesion detection even when the lesion is freely mobile, and a 1.5 cm lesion would be difficult to detect in an enlarged ventricle, but 2 and 3 cm lesions could be detected even in the presence of moderate ventricular enlargement.

Heart↗
PubMedDate not supplied

Prevalence of human foamy virus-related sequences in the Korean population.

The possible association of human foamy virus (HFV) with human thyroid disorders such as Graves' disease (GD) has been a topic of controversy due to the inconsistent results reported by several groups of investigators. Here we report the investigation of the presence of HFV-related sequences in the Korean population. DNA was obtained from peripheral blood lymphocytes from 24 GD patients and 23 healthy blood donors and subjected to PCR amplification using three sets of nested primers derived from gag, env, and LTR regions of the HFV genome. Contrary to previously reported studies, our analysis identified HFV-related sequences in the genomes of both healthy individuals and the GD patients. However, the nature of the HFV genome present in each group appeared to be different. We detected all 3 regions of HFV-related sequences in 29% of the HFV-positive GD patients, while no samples in the control group amplified all three regions. This suggests that the LTR may be used as a tool for screening for HFV in GD patients. Our data favor the hypothesis of a relationship between GD and the presence of HFV-related sequences, though in a complex way.

Adult↗