Biomedical subjects

B S Lee

Publications and source records attributed to B S Lee.

At least 55 records · Page 3Linked to original sources

PubMed2000

Identification of the novel K15 gene at the rightmost end of the Kaposi's sarcoma-associated herpesvirus genome.

Kaposi's sarcoma-associated herpesvirus (KSHV) encodes a distinct open reading frame called K15 at a position equivalent to the gene encoding LMP2A of Epstein-Barr virus (EBV). K15 isolates from body cavity-based lymphoma (BCBL) cells exhibited a dramatic sequence variation and a complex splicing pattern. However, all K15 alleles are organized similarly with the potential SH2 and SH3 binding motifs in their cytoplasmic regions. Northern blot analysis showed that K15 was weakly expressed in latently infected BCBL-1 cells, and the level of its expression was significantly induced by tetradecanoyl phorbol acetate stimulation. K15 encoded 40- to 55-kDa proteins, as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and was localized at the cytoplasm and plasma membrane. To demonstrate the signal-transducing activity of the K15 protein, we constructed a chimeric protein in which the cytoplasmic tail of the human CD8alpha polypeptide was replaced with that of KSHV K15. While the CD8-K15 chimera was not capable of eliciting cellular signal transduction upon stimulation with an anti-CD8 antibody, it significantly inhibited B-cell receptor signaling, as evidenced by a suppression of tyrosine phosphorylation and intracellular calcium mobilization. This inhibition required the putative SH2 or SH3 binding motif in the cytoplasmic region of K15. Biochemical study of CD8-K15 chimeras showed that the cytoplasmic region of K15 was constitutively tyrosine phosphorylated and that the tyrosine residue within the putative SH2 binding motif of K15 was a primary site of phosphorylation. These results demonstrate that KSHV K15 resembles LMP2A in genomic location, splicing pattern, and protein structure and by the presence of functional signal-transducing motifs in the cytoplasmic region. Thus, KSHV K15 is likely a distant evolutionary relative of EBV LMP2A.

Alleles↗

PubMed1999

Interaction between vacuolar H(+)-ATPase and microfilaments during osteoclast activation.

Vacuolar H(+)-ATPases (V-ATPases) are multisubunit enzymes that acidify compartments of the vacuolar system of all eukaryotic cells. In osteoclasts, the cells that degrade bone, V-ATPases, are recruited from intracellular membrane compartments to the ruffled membrane, a specialized domain of the plasma membrane, where they are maintained at high densities, serving to acidify the resorption bay at the osteoclast attachment site on bone (Blair, H. C., Teitelbaum, S. L., Ghiselli, R., and Gluck, S. L. (1989) Science 249, 855-857). Here, we describe a new mechanism involved in controlling the activity of the bone-resorptive cell. V-ATPase in osteoclasts cultured in vitro was found to form a detergent-insoluble complex with actin and myosin II through direct binding of V-ATPase to actin filaments. Plating bone marrow cells onto dentine slices, a physiologic stimulus that activates osteoclast resorption, produced a profound change in the association of the V-ATPase with actin, assayed by coimmunoprecipitation and immunocytochemical colocalization of actin filaments and V-ATPase in osteoclasts. Mouse marrow and bovine kidney V-ATPase bound rabbit muscle F-actin directly with a maximum stoichiometry of 1 mol of V-ATPase per 8 mol of F-actin and an apparent affinity of 0.05 microM. Electron microscopy of negatively stained samples confirmed the binding interaction. These findings link transport of V-ATPase to reorganization of the actin cytoskeleton during osteoclast activation.

Actin Cytoskeleton↗

PubMed1999

Atypical processing of amyloid precursor fusion protein by proteolytic activity in Pichia pastoris.

Secretases catalyze the production of important proteolytic products of the amyloid precursor protein. We expressed a fusion protein that contained horseradish peroxidase, fragment 590-695 of amyloid precursor protein, and c-myc and polyhistidine tags in Pichia pastoris. It secreted a 50-kDa N-terminal fragment; a 15-kDa C-terminal fragment accumulated in cells. The N-terminal fragment exhibited peroxidase activity and reacted with antibodies specific for peptides within the sequences -2 to 15 and 21-37 of beta-amyloid peptide. The C-terminal fragment reacted with antibodies that recognize the sequences 649-664 and 676-695 of amyloid precursor protein and the C-terminal c-myc tag. To locate the cut site, the C-terminal fragment was metabolically labeled with either [(35)S]Met or [(3)H]Lys and radiosequenced. A major component, derived from a cleavage at Gly(25)-Ser(26) of beta-amyloid, was detected. Results suggest a predominant atypical cleavage, like that observed in Down Syndrome fibroblasts, occurs between the alpha- and gamma-sites.

Amino Acid Sequence↗

PubMed1999

RNA polymerase switch in transcription of yeast rDNA: role of transcription factor UAF (upstream activation factor) in silencing rDNA transcription by RNA polymerase II.

Transcription factor UAF (upstream activation factor) is required for a high level of transcription, but not for basal transcription, of rDNA by RNA polymerase I (Pol I) in the yeast Saccharomyces cerevisiae. RRN9 encodes one of the UAF subunits. We have found that rrn9 deletion mutants grow extremely slowly but give rise to faster growing variants that can grow without intact Pol I, synthesizing rRNA by using RNA polymerase II (Pol II). This change is reversible and does not involve a simple mutation. The two alternative states, one suitable for rDNA transcription by Pol I and the other favoring rDNA transcription by Pol II, are heritable not only in mitosis, but also in meiosis. Thus, S. cerevisiae has an inherent ability to transcribe rDNA by Pol II, but this transcription activity is silenced in normal cells, and UAF plays a key role in this silencing by stabilizing the first state.

Crosses, Genetic↗

PubMed1999

Is beta-poly(L-malate) synthesis catalysed by a combination of beta-L-malyl-AMP-ligase and beta-poly(L-malate) polymerase?

beta-Poly(L-malate) is supposed to function in the storage and transport of histones, DNA polymerases and other nuclear proteins in the giant syncytical cells (plasmodia) of myxomycetes. Here we report on the biosynthesis of [14C]beta-poly(L-malate) from injected L-[14C]malate in the plasmodium of Physarum polycephalum. The effects of KCN, arsenate, adenosine 5'-(alpha, beta-methylene)triphosphate, adenosine 5'-(beta, gamma-methylene)triphosphate, guanosine 5'-(beta, gamma-methylene)triphosphate, desulfo coenzyme A and phenylarsinoxid on beta-poly(L-malate) synthesis were studied after their coinjection with L-[14C]malate. The synthesis was not affected by KCN or desulfo coenzyme A, but was blocked by arsenate and adenosine 5'-(alpha,beta-methylene)triphosphate. The plasmodium lysate catalysed an L-malate-dependent ATP-[32P]pyrophosphate exchange, but was devoid of beta-poly(L-malate) synthetic activity under all experimental conditions tested. The results suggested an extramitochondrial synthesis of beta-poly(L-malate), involving the polymerization of beta-L-malyl-AMP. It is assumed that the lack of synthesis in the lysate is caused by the inactivation of beta-poly(L-malate) polymerase involving a cell injury kinase pathway. Because injected guanosine 5'-(beta, gamma-methylene)triphosphate blocks the synthesis, the injury signal is likely to be GTP dependent.

Acyltransferases↗

PubMed1999

Management of foreign bodies in the gastrointestinal tract: an analysis of 104 cases in children.

BACKGROUND AND STUDY AIMS: Ingested foreign bodies may be managed by endoscopy, observation, or surgery. The aim of the study was to investigate the methods of removal of foreign bodies according to type and location, success rates, and complications. PATIENTS AND METHODS: The charts of 104 children who had ingested foreign bodies were retrospectively reviewed. RESULTS: Of the patients, 80 (76.9%) were managed endoscopically. The overall success rate for endoscopic management was 98.8%. There were no complications during endoscopic interventions. In 23 cases the foreign bodies spontaneously passed through the gastrointestinal tract (22.1%). Surgical removal of a foreign body was done in only one case (0.96%). The majority of the foreign bodies which were located in the upper gastrointestinal tract could be removed endoscopically regardless of the nature of the material. Foreign bodies in the small and large intestine tended to pass through spontaneously without complications. CONCLUSIONS: It appears that the endoscopic approach is the preferable method for the extraction of upper gastrointestinal foreign bodies in child patients because of its high success rate, and that foreign bodies in the small and large intestine tend to be passed spontaneously without complications.

Adolescent↗

PubMed1999

Vacuolar H+-ATPase activity and expression in mouse bone marrow cultures.

We examined vacuolar H+-ATPase (V-ATPase) structure, enzymatic properties, and protein and mRNA expression from mouse marrow cultured in the presence or absence of 1,25-dihydroxyvitamin D3 (1, 25(OH)2D3), which stimulates formation of bone-resorptive osteoclasts. V-ATPases from osteoclast-containing cultures were similar in ion and inhibitor sensitivities to the enzyme from kidney-derived sources. Immunopurified V-ATPase from 1,25(OH)2D3-stimulated cultures exhibited 20-fold greater ATPase activity than the enzyme from unstimulated cultures, which do not contain osteoclasts. In contrast, 1,25(OH)2D3-treated cultures contained only 2-fold more assembled V-ATPase, as determined by immunoprecipitation. Quantitative reverse transcription-polymerase chain reaction (RT-PCR) and immunoblot analysis similarly showed approximately 2-fold increases of V-ATPase mRNA and protein levels in 1,25(OH)2D3-treated cultures. The bulk of the relative difference in V-ATPase activity between the two cultures was due to a 10-fold difference in enzyme specific activity. Quantitative RT-PCR also revealed that expression levels of V-ATPase mRNAs reflected the stoichiometry of enzyme subunits in the assembled complex. These data indicate that in mouse bone marrow cultures, V-ATPase expression is controlled at the level of mRNA, and that increases in subunit expression and assembly cannot account for the 20-fold difference in enzyme activity in osteoclast-containing cultures. Therefore, osteoclast V-ATPase activity may be regulated by subtle alterations in enzyme structure or associated factors.

Animals↗

PubMed1999

A decrease in circulating levels of immunoreactive insulin-like growth factor binding protein-1 (IGFBP-1) after endometrial ablation using a gynecologic resectoscope.

To determine how endometrium alone would contribute to maintaining the circulating levels of Insulin-like growth factor binding protein-1 in vivo, serum immunoreactive IGFBP-1 levels were measured in 19 patients undergoing endometrial ablation using gynecologic resectoscopy. After endometrial ablation there was a significant decrease in the mean levels of circulating IGFBP-1, which was not correlated with the menstrual cycle. This result indicates that the endometrium is one of the sources of the circulating IGFBP-1.

Adult↗

PubMed1999

Operative laparoscopy in treating benign ovarian cysts.

This study was undertaken to evaluate the clinical usefulness of operative laparoscopy in treatment of benign ovarian cysts. A retrospective study was carried on 468 operative laparoscopy cases performed from September 1995 to September 1998 at Yonsei University College of Medicine, Department of Obstetrics and Gynecology. Patient characteristics, specimen pathology, perioperative morbidity, and perioperative complications were reviewed. The percentage of operative laparoscopy increased steadily from 20.7% in 1996, 33.9% in 1997, to 49.7% in 1998. The mean age of patients was 33.66.5 (mean +/- SD) years and the mean hospital stay was less than 2 days. Types of surgery performed were cystectomy (n = 234), salpingo-oophorectomy (n = 126), oophorectomy (n = 63), and fulguration (n = 45), in decreasing order. Depending on the pathology of the ovarian cyst, the mean operation time was in the range of 80 to 110 minutes. Perioperative complications included 5 cases of subcutaneous emphysema, 10 cases of abdominal wall hematoma, 7 cases of trocar site bleeding, 3 cases of bowel injury, and 1 case of bladder injury. In conclusion, operative laparoscopy in treating benign ovarian cysts provides advantages such as less need to perform laparotomy, smaller skin incision, less perioperative discomfort, minimal tissue handling and trauma, and shorter hospital stay. Nevertheless, the risk of unrecognized ovarian malignancy cannot be absolutely excluded, therefore careful patient selection is mandated.

Adolescent↗

PubMed1999

T cell subsets in chronic hepatitis B and the effect of prednisolone withdrawal and interferon alpha-2b.

OBJECTIVES: The evaluations of the pathogenetic roles of cell mediated immunity and of the preventive effect for disease progression with interferon(IFN) treatment in patients with chronic active hepatitis-B(CAH-B) are the objectives of this study. METHODS: Thirty-two patients with CAH-B were treated with interferon alpha-2b(IFN alpha-2b) with prednisolone withdrawal and 30 control patients were treated with conventional hepatotonics for 6 months. Peripheral total T cell fractions and T cell subsets of the patients with CAH-B, treated with IFN alpha-2b with prednisolone withdrawal, were examined 1 month before administration of prednisolone, and compared with 12 normal controls for assessing the potential role of cellular immunity in the development of CAH-B. To estimate the effectiveness of IFN therapy for the patients with CAH-B, levels of various liver function tests, HBsAg, anti-HBs, HBeAg, anti-HBe, HBV DNA, anti-HCV and others were assessed for the treatment group and compared with control patients at pre- and post-treatment period each. RESULTS: The value of CD4 was significantly lower in patients with CAH-B than normal controls (36.3 +/- 7.7% vs 42.1 +/- 5.7%, p < 0.05) and the value of CD8 was significantly higher in patients with CAH-B than normal controls (30.6 +/- 10.3% vs 24.3 +/- 5.2%, p < 0.05) before prednisolone administration. The patients in responder group (n = 26) had significantly lower CD4 cells compared with normal controls, but non-responders (n = 6) did not have. The levels of liver function test(LFT) in the patients with IFN alpha-2b treatment with prednisolone withdrawal were not different from the control patient group at pretreatment, but significantly lower than control patient group's after treatment, regardless of response to IFN alpha-2b treatment with prednisolone withdrawal. CONCLUSIONS: The cellular immunity of the host may have a potential role in the pathogenesis of chronicity of hepatitis B infection. IFN alpha-2b treatment with prednisolone withdrawal may be regarded as one of the effective treatment modalities for the inhibition of disease progression in patients with CAH-B.

Adult↗

PubMed1998

Posttranslational inhibition of Ty1 retrotransposition by nucleotide excision repair/transcription factor TFIIH subunits Ssl2p and Rad3p.

rtt4-1 (regulator of Ty transposition) is a cellular mutation that permits a high level of spontaneous Ty1 retrotransposition in Saccharomyces cerevisiae. The RTT4 gene is allelic with SSL2 (RAD25), which encodes a DNA helicase present in basal transcription (TFIIH) and nucleotide excision repair (NER) complexes. The ssl2-rtt (rtt4-1) mutation stimulates Ty1 retrotransposition, but does not alter Ty1 target site preferences, or increase cDNA or mitotic recombination. In addition to ssl2-rtt, the ssl2-dead and SSL2-1 mutations stimulate Ty1 transposition without altering the level of Ty1 RNA or proteins. However, the level of Ty1 cDNA markedly increases in the ssl2 mutants. Like SSL2, certain mutations in another NER/TFIIH DNA helicase encoded by RAD3 stimulate Ty1 transposition. Although Ssl2p and Rad3p are required for NER, inhibition of Ty1 transposition is independent of Ssl2p and Rad3p NER functions. Our work suggests that NER/TFIIH subunits antagonize Ty1 transposition posttranslationally by inhibiting reverse transcription or destabilizing Ty1 cDNA.

Adenosine Triphosphatases↗

PubMed1998

Interferon-alpha is a potent inhibitor of basic fibroblast growth factor-stimulated cell proliferation in human uterine cells.

PROBLEM: Abnormal uterine bleeding is a significant health problem for many women and is the number-one reason for performing hysterectomy in the United States. Leiomyomas (uterine fibroids) are benign neoplasms that are a frequent cause of abnormal uterine bleeding. The goal of this study was to assess the effects of the anti-angiogenic cytokine, interferon (INF)-alpha, on the proliferation of both leiomyoma and normal uterine cells. METHOD OF STUDY: Primary cultures of leiomyoma, myometrial, and endometrial stromal cells were established for in vitro study. The effects of INF-alpha (10, 100, and 1000 U/ml) were tested on serum-stimulated and basic fibroblast growth factor-stimulated cell proliferation using the [3H]thymidine incorporation assay. RESULTS: INF-alpha was a potent inhibitor of cell proliferation for all three cell types, with endometrial stromal cells showing the greatest sensitivity. The antiproliferative effect did not appear to result from toxic effects on the cells. CONCLUSION: INFs may prove to be useful therapeutic agents for the treatment of leiomyoma-related abnormal uterine bleeding.

Cell Division↗

PubMed1998

Pirfenidone: a novel pharmacological agent that inhibits leiomyoma cell proliferation and collagen production.

There are currently no effective, long-term drug therapies for the treatment of leiomyomas. Pirfenidone (Marnac, Inc.) is an antifibrotic agent that is being tested for use in patients with pulmonary fibrosis. Because leiomyomas are characterized also by increased cell proliferation and tissue fibrosis, we examined the effects of pirfenidone on cell proliferation and collagen expression in cultured myometrial and leiomyoma smooth muscle cells. Effects of pirfenidone on proliferation of myometrial and leiomyoma cells were measured using tritiated thymidine incorporation assays and changes in actual cell numbers. Possible cytotoxic effects were examined using lactate dehydrogenase assays and trypan blue exclusion. Effects on collagen type I and type III production were assessed by Northern blotting. Doses of pirfenidone tested were: 0, 0.01, 0.1, 0.3, and 1.0 mg/mL. Serum-stimulated increases in DNA synthesis and cell proliferation by myometrial and leiomyoma cells were significantly inhibited in a dose-dependent manner by pirfenidone. Densitometric analysis of Northern blots showed significantly decreased expression of collagen type I and type III messenger RNAs in both leiomyoma and myometrial cells. Lactate dehydrogenase assays and trypan blue exclusion measurements showed no cytotoxic effect of pirfenidone at concentrations that inhibited cell proliferation and collagen production. Pirfenidone is an effective inhibitor of myometrial and leiomyoma cell proliferation in vitro and reduces the messenger RNA levels of collagen types I and III in a dose-dependent manner. This compound may prove to be an effective nonsteroidal therapy for treatment of uterine leiomyomas.

Antineoplastic Agents↗

PubMed1998

Effectiveness of prenatal ultrasonography in detecting fetal anomalies and perinatal outcome of anomalous fetuses.

A retrospective study was performed over a 5-year period (1990-94) to evaluate the effectiveness of prenatal ultrasonography in terms of sensitivity, specificity, and predictive values in detecting fetal anomalies by comparing prenatal ultrasonic results with anomalies found in neonates and the perinatal outcome of anomalous fetuses. Minor congenital anomalies as listed and defined in the Eurocat Register were excluded. From a total of 5544 singletons, 4819 had at least one ultrasound scan (87%), of which 3004 at low risk and 1815 (38%) at high risk for anomalies had routine screening (RS) and indicated scanning (IS), respectively. A total of 136 fetuses were structurally abnormal (2.82%, RS and IS: 0.77% and 6.23%) and 200 major anomalies (RS and IS: 37 and 163) were recorded. The overall sensitivity of the ultrasound test was 78.7% (RS and IS: 34.8% and 87.6%, P < 0.01) for abnormal fetuses and 58.0% (RS and IS: 29.7% and 64.4%, P < 0.01) for anomalies. The overall specificity was 99.9% and the positive and negative predictive values were 97.3% and 99.4%, respectively; these values did not differ significantly between the two groups. The sensitivity of ultrasound for the detection of abnormal fetuses before 24 weeks was 22.8% (RS and IS: 13.0% and 24.8%) which was associated with a 61% (25/41) termination rate (RS and IS: 25% and 75.9%, P < 0.01) and a 24.4% (10/41) postnatal survival rate (RS and IS: 41.7% and 17.2%). The overall survival rate following pre- and postnatal correction of anomalies was 44.9% (RS and IS: 60.9% and 41.6%). For the detection of fetal anomalies anatomic ultrasound scanning is necessary during pregnancy, irrespective of pregnancy condition. Early detection of fetal anomalies could offer the option of pregnancy termination.

Abortion, Induced↗

PubMed1998

Plasma membrane V-ATPases in proton-transporting cells of the mammalian kidney and osteoclast.

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Animals↗

PubMed1997

Granulocyte colony-stimulating factor upregulates the vacuolar proton ATPase in human neutrophils.

We have previously shown that granulocyte colony-stimulating factor (G-CSF ) delays spontaneous neutrophil apoptosis through activation of the vacuolar proton ATPase (v-ATPase). We have now examined the regulation of the v-ATPase in neutrophils exposed to G-CSF in vitro. When neutrophils were cultivated in the absence of G-CSF, the 57-kD cytosolic B subunit of the v-ATPase disappeared within 1 to 2 hours, its loss preceding the nuclear changes of apoptosis and coinciding with the onset of acidification. By contrast, in neutrophils cultured for 2 hours in the presence of G-CSF, the amount of the 57-kD subunit was similar to that in freshly isolated neutrophils. However, inhibition of protein synthesis with cycloheximide and actinomycin D led to loss of the 57-kD subunit even in the presence of G-CSF. These results indicated that ongoing protein synthesis was required to maintain the v-ATPase, and further suggested that G-CSF acted, at least in part, by maintaining synthesis of the 57-kD cytosolic subunit. G-CSF also promoted the translocation of the 57-and 33-kD cytosolic v-ATPase subunits to the membrane. Our findings suggested two coordinate mechanisms by which the activity of the v-ATPase could be increased by G-CSF: the synthesis of cytosolic v-ATPase subunits and their translocation to the membrane.

Adult↗

PubMed1997

Upstream NF-kappaB site is required for the maximal expression of mouse inducible nitric oxide synthase gene in interferon-gamma plus lipopolysaccharide-induced RAW 264.7 macrophages.

Transient transfection assays with various deletion mutants of the mouse inducible nitric oxide synthase (iNOS) promoter linked to a CAT reporter gene demonstrated that, besides the downstream NF-kappaB site, the region from -973 to -925 which contains a potential binding site for NF-kappaB (upstream NF-kappaB site) also mediated lipopolysaccharide (LPS)-inducibility in mouse macrophage cell line RAW 264.7. Site-specific mutation of three conserved nucleotides within the upstream NF-kappaB site abolished additional induction by LPS as well as maximal expression of iNOS by IFN-gamma plus LPS. In contrast, site-specific mutation of the downstream NF-kappaB site caused almost all reduction in expression of the reporter gene by LPS or LPS plus IFN-gamma. Electrophoretic mobility shift assays with the two NF-kappaB sites showed LPS-induced NF-kappaB binding to both probes and its higher affinity to the upstream NF-kappaB site. Taken together, these suggest that the upstream NF-kappaB site having enhancer function, besides the downstream NF-kappaB site as a core promoter, is essential for maximal expression of the iNOS gene.

Animals↗

PubMed1997

A novel transcription factor regulates expression of the vacuolar H+-ATPase B2 subunit through AP-2 sites during monocytic differentiation.

During monocyte-to-macrophage differentiation, the cellular content of vacuolar H+-ATPase (V-ATPase) increases more than 4-fold. We have shown previously that amplified expression of the B2 subunit of the V-ATPase occurs solely by increased transcription, and that the 5'-untranslated region of the B2 gene, containing multiple consensus binding sites for the transcription factors AP-2 and Sp1, is required for this expression. The present study demonstrates that AP-2 binding sequences are essential for increased transcription from the B2 promoter during monocyte-macrophage differentiation and that AP-2, expressed exogenously in THP-1 and other cells, activates transcription from the B2 promoter. In mobility shift assays, a nuclear factor from THP-1 and U-937 cells was identified that binds to several AP-2 response elements within the B2 promoter, but does not react with AP-2 antibodies, and has a DNA sequence binding affinity profile that differs from AP-2. These findings suggest that a novel AP-2-like transcription factor is responsible for V-ATPase B subunit amplification during monocyte differentiation.

Base Sequence↗