Biomedical subjects
Publications and source records attributed to Y C Liu.
Pulmonary echinococcosis is a rare disease in Taiwan and has never been reported in Taiwan's literatures. Here we report an overseas Chinese from Calcutta, India, presenting with recurrent hemoptysis and chest pain and with two big lung masses on chest roentgenogram. Rupture and spike fever ensured after fine needle aspiration of the cysts. Successful surgical intervention was obtained and echinococcal infection was documented pathologically.
Cyclin D1, DNA topoisomerase I, and proliferating cell nuclear antigen (PCNA) are three important cell cycle regulatory proteins. Recently, their promoters have been isolated, thus facilitating molecular analysis of transcriptional control mechanisms of these genes. Transcription of these three promoters in stable K562 transfectants during different cell cycle phases was analyzed after cell cycle synchronization. About 1 kb of 5' flanking region from either cyclin D1 or DNA topoisomerase I gene is sufficient to confer G1- or S-phase-specific transcription activity to chloramphenicol acetyltransferase (CAT) reporter genes, respectively. In contrast, 2.8 kb of 5' flanking sequences from the PCNA gene led to constitutive transcription, but the inclusion of a segment of the PCNA gene first intron, which contains evolutionarily conserved sequences, could enhance transcription in G1/S-enriched nuclei. This PCNA intron region contains a binding site recognized by the transcription factor E2F. To test whether this site is functional, we cotransfected PCNA-CAT genes with E2F-1 and DP-1 expression plasmids. Expression of the E2F-1/DP-1 heterodimer activated the CAT gene with the PCNA intron. Therefore, this intron region, involved in transcriptional activation at the cell cycle G1/S boundary, is also E2F inducible.
This study consisted of 10 cases of chronic B-cell lymphoproliferative disorders that had simultaneous specimens obtained from both bone marrow and peripheral sites for flow cytometric immunophenotyping. The immunophenotyping results of peripheral sites from all 10 cases showed a monoclonal B-cell proliferation expressing monoclonal surface immunoglobulin, CD19, CD20, HLA-DR, and CD5 (except 1 case). Eight (80%) of the 10 cases, however, demonstrated discordant immunophenotypes with myeloid-associated marker expression (CD13, CD11b, and/or CD15) found only in the bone marrow. Patients with CD13 or CD11b marker expression in the bone marrow followed an aggressive clinical course with advanced Rai's stage and a diffuse or mixed bone marrow infiltration pattern or disease transformation. These results indicate that discordant immunophenotypes of malignant cells from different body sites occur in chronic B-cell lymphoproliferative disorders and are not uncommon. Additionally; myeloid-associated markers, which some investigators have described as being associated with an unfavorable clinical course, may be expressed only in bone marrow specimens in these disorders. Thus, bone marrow specimens may be preferential in determining myeloid-associated marker expression in chronic B-cell lymphoproliferative disorders.
Between 1 August 1993 and 31 July 1994, 135 clinical isolates of Moraxella catarrhalis were collected from 12 large medical laboratories in Taiwan. The majority of specimens came from sputum (124 isolates). Other specimens included four isolates from throats, three isolates from wounds or pus, two isolates from eyes, one isolate from blood and one from cerebrospinal fluid. Epidemiologically, M. catarrhalis isolates were found frequently in winter and spring with a peak in February, and only sporadically from April to September. The overall rate of beta-lactamase producing isolates was 98.5% (132/135). All isolates were considered to be ampicillin-resistant, none were found to be resistant to other beta-lactam agents. Among other antimicrobial agents, all isolates were susceptible to chloramphenicol, erythromycin, roxithromycin, ofloxacin and ciprofloxacin, but uniformly resistant to trimethoprim (minimum inhibitory concentration (MIC) > or = 4 micrograms/mL, zone diameter < or = 19 mm). There were 12 isolates (8.8%) resistant to sulfamethoxazole (MIC > or = 32 micrograms/mL, zone diameter < or = 19 mm) and 19 isolates (14.4%) resistant to tetracycline (MIC > or = 16 micrograms/mL, zone diameter < or = 19 mm). The high level of resistance to ampicillin due to beta-lactamase production indicates that this is no longer a reliable agent for the treatment of M. catarrhalis infections. Among the beta-lactam agents tested, amoxicillin + clavulanate and the cephalosporins were active. These agents appear to be reliable first-line therapies when infection with M. catarrhalis is suspected. Misidentification of the species and difficulties in determining susceptibility to ampicillin are still widespread in Taiwanese laboratories. The application of the butyrate hydrolysis test and an appropriate test for beta-lactamase production is necessary for the resolution of these problems.
Dysgenetic gonads are well known to be associated with gonadoblastoma and various germ cell tumors, but very rarely with choriocarcinoma. We describe a 16-year-old, phenotypic female patient with a 46XY karyotype who developed gonadoblastoma on the right gonad and choriocarcinoma on the left. There was no co-existence of the two tumor cell types in the same gonad. This case emphasizes the importance of bilateral gonadectomy for "46XY female" patients, as soon as the cytogenetic evidence is known.
Secretion of bioactive glycosylation-inhibiting factor (GIF) appears to be restricted to suppressor T (Ts) cells, although various human and murine cell line cells secrete the 13-kDa peptide that reacts with anti-GIF. Nucleotide sequences of GIF cDNA from the Ts and non-Ts cells are identical, indicating that bioactive GIF and inactive GIF have an identical amino acid sequence. A stable transfectant of human GIF (hGIF) cDNA in BMT10 cells secretes inactive GIF peptide, whereas transfection of a chimeric cDNA encoding a fusion protein consisting of the N-terminal region of procalcitonin precursor and hGIF into the same cells results in secretion of bioactive GIF. Evidence was obtained that the fusion protein goes into the endoplasmic reticulum and is cleaved for the secretion of mature GIF peptide, whereas the inactive 13-kDa peptide synthesized by the former transfectant does not go through the endoplasmic reticulum. However, a stable transfectant of hGIF cDNA in mouse Ts hybridoma contains inactive GIF in the cytosol and secretes bioactive hGIF without participation of the endoplasmic reticulum-Golgi system. Heterogeneity of the 13-kDa hGIF from the transfectant was detected in two-dimensional electrophoresis. The results suggested that Ts cells have a machinery that converts a portion of inactive cytosolic GIF peptide to bioactive GIF during secretion.
Explore the source record for details and available documents.
We have examined the interaction of a series of mutant trp repressors with various operator DNA sequences using gel retardation. Binding to 40 base pairs (bp) TrpEDCBA operator yielded patterns distinct from the wild-type protein for superrepressors EK13, EK18, and EK49, with a protein-DNA complex of higher stoichiometry (three dimers/operator) than observed for wild-type repressor (two dimers/operator). This higher stoichiometry complex may contribute to the enhanced binding affinity and higher protein-operator stability observed for the superrepressors. In contrast, DN46 displayed the same complexes characteristic of the wild-type protein, although the complex of a single dimer with operator was more prominent in the DN46 binding pattern than wild-type despite higher apparent affinity of this protein for TrpEDCBA operator than wild-type protein. The binding of AV77 was indistinguishable from the wild-type protein. Similar patterns to that found for TrpEDCBA were also observed for the 40-bp aroH operator and symmetrized derivatives of TrpEDCBA for these superrepressors. Binding of EK13, EK18, and EK49 superrepressors to half-site DNAs, composed of 20 bp of TrpEDCBA sequence coupled with 20 bp of lac operator sequence, yielded 2:1 complex as the primary product with no detectable 3:1 complex; thus, two half-sites appear to be required for generation of the 3:1 complex. Mutation in the tryptophan-binding site can also generate higher order complexes with TrpEDCBA DNA as demonstrated by the binding of VA58; the presence of 3:1 complex with this protein was also dependent on the presence of two half-sites. In addition to effects of sequence changes in the protein, the ligand employed can influence the binding pattern, as demonstrated for EK49 and VA58 using 5-methyl-tryptophan; the 3:1 complex is produced more prominently and at lower protein concentration for both mutants. It is apparent from these data that binding of the trp repressor to DNA is influenced by the operator sequence, the nature of the corepressor, as well as interactions (perhaps involving the N-terminal regions) that occur within and between the dimeric structure of this protein.
Ligand-induced dimerization is a key step in the activation of receptor tyrosine kinases, including the epidermal growth factor receptor, stem cell factor receptor (c-kit), and colony-stimulating factor 1 receptor (c-fms). The erythropoietin receptor (EPOR), a member of the cytokine receptor family, contains no kinase motif and its activation mechanism remains unclear. Here we show that chimeric receptors carrying the extracellular domain of the epidermal growth factor receptor or c-kit linked to the cytoplasmic domain of the EPOR, transmitted epidermal growth factor or stem cell factor-dependent proliferation signals in an interleukin 3-dependent cell line. The chimeric receptors as well as the wild-type EPOR also mediated the ligand-induced tyrosine phosphorylation of a set of similar proteins. Moreover, erythropoietin triggered mitogenic signals of chimeric receptors carrying the extracellular domain of the EPOR linked to the tyrosine kinase of c-fms. These data demonstrate the interchangeability of domains between two distinct receptor families and suggest that ligand-induced dimerization is a key step in activating the EPOR.
The stem cell factor is a glycoprotein hormone which regulates the proliferation and differentiation of primitive hematopoietic cells through its interaction with a tyrosine kinase transmembrane receptor which is encoded by the c-kit proto-oncogene. To examine whether a murine c-kit receptor can be functional in murine interleukin-3 (mIL-3)-dependent hematopoietic cell line, we introduced the murine c-kit cDNA into mIL-3-dependent pro-B cell line Ba/F3. One of the resulting clones, Ba/F3 clone BF-K96, expressed the 140 kDa protein recognized by anti-c-kit monoclonal antibody and the expressed c-kit receptor protein on the cell surface bound to a radiolabeled soluble form of murine stem cell factor (mSCF) with high affinity. BF-K96 clone expressing the c-kit receptor could proliferate in response to mSCF in the absence of mIL-3. The cell clone could also grow in co-culture with mouse 3T3 cells which are endogeneously expressing a membrane-associated type of mSCF on their cell surfaces. These findings demonstrate that the c-kit receptor expressed on mIL-3-dependent hematopoietic cell line Ba/F3 transduce the mSCF-dependent growth signal, indicating that established cell clone will provide a unique cellular system for the study of SCF/c-kit signal transduction mechanism.
Nonanastomotic aneurysm formation in autogenous vein grafts, although rarely described, has been uniformly associated with advanced atherosclerotic change of the vein wall. In the case reported, histologic examination of an in situ vein graft aneurysm demonstrates obliteration of normal vessel wall architecture by penetrating atherosclerotic plaque. Although these findings do not prove a causal relationship, they do provide additional support for atherosclerosis as an etiologic factor in aneurysm disease.
The trp repressor of Escherichia coli (TR), although generally considered to be dimeric, has been shown by fluorescence anisotropy of extrinsically labeled protein to undergo oligomerization in solution at protein concentrations in the micromolar range (Fernando, T., and C. A. Royer 1992. Biochemistry. 31:3429-3441). Providing evidence that oligomerization is an intrinsic property of TR, the present studies using chemical cross-linking, analytical ultracentrifugation, and molecular sieve chromatography demonstrate that unmodified TR dimers form higher order aggregates. Tetramers and higher order species were observed in chemical cross-linking experiments at concentrations between 1 and 40 microM. Results from analytical ultracentrifugation and gel filtration chromatography were consistent with average molecular weight values between tetramer and dimer, although no plateaus in the association were evident over the concentration ranges studied, indicating that higher order species are populated. Analytical ultracentrifugation data in presence of corepressor imply that corepressor binding destabilizes the higher order aggregates, an observation that is consistent with the earlier fluorescence work. Through the investigation of the salt and pH dependence of oligomerization, the present studies have revealed an electrostatic component to the interactions between TR dimers.
Cefepime is a new parenterally active fourth-generation cephalosporin which is undergoing in vitro and in vivo evaluations. Using the standard agar dilution method we compared the in vitro activity of this drug with other cephalosporins and ciprofloxacin against clinical isolates of Escherichia coli (98 strains), Klebsiella pneumoniae (99 strains), Acinetobacter spp. (24 strains), Pseudomonas aeruginosa (98 strains), Haemophilus influenzae (108 strains), Staphylococcus aureus (100 strains), Enterococcus spp. (45 strains), Streptococcus pneumoniae (10 strains), Streptococcus pyogenes (group A; 19 strains) and Streptococcus agalactiae (group B; 36 strains). Cefepime showed excellent activity against E. coli and K. pneumoniae, inhibiting 90% of these isolates at 0.12 mg/l. The in vitro activity of cefepime was superior to or comparable to the third-generation cephalosporins tested but was inferior to ciprofloxacin against Acinetobacter spp. and P. aeruginosa. Against H. influenzae, whether or not the strains produced beta-lactamase, its activity was similar to comparable drugs. All 84 isolates of methicillin-susceptible S. aureus were inhibited by 8 mg/l of cefepime whereas, like other cephalosporins, it had little activity against methicillin-resistant S. aureus. Of the 45 enterococci isolates tested, 44.4% were inhibited by 8 mg/l of cefepime. Against streptococci, its activity was superior to any drug tested. This in vitro study indicates that cefepime has the potential to be a valuable agent for the treatment of community- and hospital-acquired cutaneous, respiratory and urinary tract infections.
We report a 67-year-old male with pneumonia in which Chlamydia pneumoniae was identified by serologic studies as the causative agent. After initial treatment failure with amoxicillin + clavulanic acid, pneumonia was successfully treated with the administration of oral azithromycin, 500 mg per day, for three days. Azithromycin is a new macrolide which has a long half-life and superior action to erythromycin. It provides a new and alternative choice in the treatment of Chlamydia pneumoniae infection in the future.
BACKGROUND: The incidence of awareness with recall during general combined with epidural anesthesia has not been previously reported. The purpose of this study was to quantify the incidence. MATERIALS & METHODS: One hundred patients were divided into two groups. Group 1 (N = 50) received general anesthesia (GA), Group 2 (N = 50) received GA and epidural anesthesia (EA) intraoperatively. No premedication was given. These patients were induced with thiopentol (5 mg/kg) or propofol (2.0 mg/kg) and anectine (1.2 mg/kg) for smooth tracheal intubation and maintained with N2O:O2 = 1.5:1.5, and isoflurane and muscle relaxant of either pavulon or atracurium. No sedatives was given. Before anesthesia, we introduced an epidural catheter into the group 2 patients. After induction, headphones with soft music were given to the patients, in both groups, throughout the operation. 20-36 hours after operation or when the patients were fully awake, we asked the patients if they had heard anything or dreamed intraoperatively. RESULTS: We found that not one of the one hundred patients heard anything or dreamed intraoperatively.
A 61-year-old pig farmer was found to be suffering from meningitis caused by Streptococcus suis type II. He was successfully treated with intravenous penicillin G but was left with permanent deafness. B-cell lymphoma was also diagnosed one year later. S. suis is a zoonotic pathogen which causes meningitis, septicemia and endocarditis in pigs. Human infection is rare and often presents as meningitis with the sequela of permanent deafness. It has previously been reported in pig rearing countries such as Holland or Hong Kong. This is the second documented case of human meningitis caused by S. suis in Taiwan, which is also a major pig rearing country in Asia. Infections caused by viridans streptococci or other beta-hemolytic streptococci in Taiwan may therefore actually be due to S. suis. Further investigation of the possibility of the underlying deficiency of humoral immunity is warranted.
Coagulation change was studied in 16 adult female patients undergoing radical hysterectomy with BPLND surgery. None had preoperative alterations in coagulation or liver function and was receiving anticoagulant or antiplatelet medication. Sixteen ASA class I-II were divided into 2 groups randomly with eight patients in each group. One group accepted autologous plasma transfusion near the end of surgery, the other group did not. Autologous plasma was retrieved by plasma saver post induction of anesthesia. Every patient received induced hypotensive anesthesia during the operation. Whole blood coagulation status was quantitated by using thromboelastography (TEG). Blood samples for TEG were obtained before induction of anesthesia, after closure of peritoneum, and 2 hours post autologous plasma transfusion or 2 hours post peritoneum closure. Most parameters measured by TEG showed improved coagulation status in autologous plasma transfusion group. We concluded that coagulation change was minimal during induced hypotension, and improved coagulation was obtained 2 hours post autologous plasma transfusion during radical hysterectomy with BPLND surgery.
Synchronous cutaneous T-cell lymphoma and low-grade B-cell lymphoproliferative disorders have rarely been reported in the same patient. Coexpression of each phenotype in the same lymph node has not, to our knowledge, been previously documented. We describe an 86-year-old man with chronic pruritus and erythroderma and recent-onset peripheral lymphadenopathy and lymphocytosis. Lymph node biopsy provided morphological and immunohistochemical evidence of concurrent small B lymphocytic lymphoma and small pleomorphic T-cell lymphoma. Immunophenotyping of nodal lymphocytes demonstrated two distinct clones: IgM-kappa B-cells with CD5 positivity and CD7 negative T-helper cells. Both immunoglobulin (heavy and light chains) and T-cell receptor (beta I and beta II) gene rearrangements were detected by Southern blot analysis of the lymph node. In contrast, the immunophenotype of lymphocytes from peripheral blood and bone marrow was exclusively that of T-helper cells with atypical CD7 deletion. Electron microscopic examination of circulating lymphocytes revealed small cerebriform Sezary cells. This case demonstrates that small lymphocytic lymphoma may coexist intranodally with cutaneous T-cell lymphoma as a unique form of composite T- and B-cell lymphoma.