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Biomedical subjects

C Y Chen

Publications and source records attributed to C Y Chen.

At least 19 recordsLinked to original sources
PubMed1992

CD10/NEP is expressed on Thy-1low B220+ murine B-cell progenitors and functions to regulate stromal cell-dependent lymphopoiesis.

To further characterize the function of the common acute lymphoblastic leukemia antigen (CALLA; CD10, neutral endopeptidase 24.11, NEP) in early lymphoid development, we have identified murine lymphoid progenitors expressing CD10/NEP and analyzed the effects of inhibiting the enzyme in in vitro assays of murine lymphoid differentiation. CD10/NEP transcripts and enzymatic activity were primarily restricted to the subpopulation of murine lymphoid progenitors, termed pro-B cells, which were isolated from bone marrow (BM) and modified Whitlock-Witte cultures and defined by coexpression of B220 and low levels of Thy-1. CD10/NEP transcripts and cell surface enzymatic activity were also detected in BM stromal cells known to support the development of B-lymphoid progenitors. In contrast, Abelson and H-ras transformed pre-B-cell lines were CD10/NEP- as were Thy-1-B220+ pre-B cells from BM and modified Whitlock-Witte cultures and Thy-1lowLin- (B220-Mac-1-GR-1-Ly-2/3-) uncommitted hematopoietic progenitors from BM. The expression of CD10/NEP on murine pro-B cells and BM stromal cells suggests a role for the enzyme in early B-cell ontogeny. In modified Whitlock-Witte cultures in which Thy-1lowLin- progenitors plated on BM stromal cells differentiate into Thy-1lowB220+ pro-B and Thy-1-B220+ pre-B cells, the addition of specific CD10/NEP inhibitors increased the number of lymphoid colonies at days 5 through 7 by 34% (P < .001). The results suggest that CD10/NEP participates in the regulation of the earliest stages of stromal cell-dependent B lymphopoiesis.

Animals↗
PubMed1992

Murine common acute lymphoblastic leukemia antigen (CD10 neutral endopeptidase 24.11). Molecular characterization, chromosomal localization, and modeling of the active site.

To further analyze CD10/NEP function in lymphoid and nonlymphoid cells using well characterized murine systems, we isolated the murine CD10/NEP homologue, determined its chromosomal location, and modeled the enzyme's active site. The murine CD10/NEP cDNA predicts a 750-amino acid (aa) type II integral membrane protein with 90% identity to the human CD10 sequence and 100% conservation of critical aa and functional motifs. The latter include the pentapeptide consensus sequence required for zinc binding and catalytic activity, additional aa associated with substrate binding, and the extracellular cysteines that participate in disulfide bonds required for enzymatic activity. Like its human homologue, murine CD10/NEP has multiple alternative 5'-untranslated region sequences. The gene is localized on the proximal half of murine chromosome 3. In Northern analysis, murine CD10/NEP transcripts are abundant in bone marrow stromal cells that support pre-B cell differentiation but are undetectable in representative Abelson transformed pre-B cell lines. The murine CD10/NEP active site was modeled by aligning critical conserved CD10/NEP residues with comparable residues in the active site of thermolysin, a bacterial metalloprotease with similar substrate specificity. The model predicts that the two enzymes have similar clefts that comprise the active site and permit zinc-dependent substrate interactions.

Amino Acid Sequence↗
PubMed1992

Crystallization and oligomeric structure of rat liver arginase.

Rat liver arginase, a manganese-metalloenzyme, has been crystallized from polyethylene glycol 8000 in N,N-bis(2-hydroxyethyl)glycine (Bicine) buffer at pH 8.5. Crystals form as either cubes or pyramids and belong to space group P3(1) (or P3(2)) with hexagonal unit cell dimensions a = b = 88.9 A, c = 114.8 A, or a = b = 88.5 A, c = 104.5 A; the variation along the c axis does not correlate with the external crystal morphology of cube or pyramid-shaped. X-ray diffraction data are measured to a limiting resolution of 2.4 A. Given the volume constraints of the unit cell it is likely that rat liver arginase is a trimer, with three 35,000 Da monomers in the asymmetric unit. This resolves a persistent ambiguity regarding the oligomeric structure of this enzyme.

Animals↗
PubMed1992

Genetic control of streptococcus-induced hepatic granulomatous lesions in mice.

Hepatic granulomatous lesions were induced in mice by a single intraperitoneal injection of 3 mg of disrupted Streptococcus pyogenes cell-wall material. Mice carrying the H-2b or H-2k haplotypes were highly susceptible to the induction and three weeks after the injection produced numerous granulomas. In contrast, mice of the H-2d haplotype were resistant and produced only a few hepatic granulomas. Resistance was inherited as a dominant trait and in the backcross generation segregated together with the H-2d phenotype. Testing of the H-2-recombinant mice indicated that the putative gene(s) determining resistance/susceptibility is located to the right of the S and to the left of the D region. This location corresponds to the recently described gene cluster consisting of tumor necrosis factor (TNF) and lymphotoxin genes and several BAT sequences. The known effect of TNF on granuloma formation in mice is consistent with a possible effect of TNF genes, and their variants, on S. pyogenes-inducibility of hepatic granulomas in mice.

Animals↗
PubMed1992

Left ventricular opacification after peripheral venous injection of a modified albumin solution.

The usefulness of a modified albumin solution was assessed in 8 dogs after peripheral venous and inferior vena cava injections. The contrast agent is a mixed solution made of glucose, albumin and glycerin, with sonicated microbubble diameter of 5.0 +/- 2.3 microns. Multiple injections (8 ml each) of this contrast agent (total 80 injections) into peripheral vein and inferior cava were performed. The blood pressure from femoral artery was measured before, during and after injections. Two-dimensional echocardiograms were recorded in a modified long axis view on videotapes for play back analysis. The pulmonary transit time and left ventricular contrast persistent time was determined for each injection. The videodensity of the region of interest (ROI) at the center of right ventricle and left ventricle was measured. The background videodensity of both ventricles was evaluated. The videodensity over the ROI of both ventricles with peak contrast enhancement was measured in all frames for 3 consecutive cardiac cycles. The peak videodensity of right and left ventricle subtracting the background videodensity of each ventricles was further calculated respectively. The injections caused no change in blood pressure or heart rate. All injections produced right ventricular contrast echo. As much as 85% of peripheral venous and 82.5% of inferior vena cava injections resulted in left ventricular contrast which was 0.68 and 0.65 as bright as that produced in the right ventricle. Pulmonary transit time and left ventricle contrast persistent time of peripheral venous injection was 4.05 +/- 0.53 and 13.67 +/- 4.28 seconds respectively. No difference of these data (3.93 +/- 0.47 and 11.65 +/- 4.66 seconds) from those produced by inferior vena cava injections were noted.(ABSTRACT TRUNCATED AT 250 WORDS)

Albumins↗
PubMed1992

A biocompatible needle-type glucose sensor based on platinum-electroplated carbon electrode.

A biocompatible needle-type glucose sensor with a 3-electrode configuration was constructed. A platinum-electroplated carbon stick was used as the working electrode, Ag/AgCl as the reference electrode, and a disposable hypodermic needle made of stainless steel as the counter electrode. A Nafion membrane, an immobilized glucose oxidase (GOD) membrane, and a biocompatible membrane with diffusion-limiting effect were coated successively onto the working electrode. The sensor showed a rapid response (< 120 s in batch operation), good reproducibility (RE < 3%), good stability (over 36 h in control serum), a wide dynamic range (5-600 mg/dL glucose), and superior biocompatibility. It was used to determine glucose in serum. The data obtained from the sensor showed good agreement with that from a clinical autoanalyzer (R > 0.95).

Biocompatible Materials↗
PubMed1992

Biosensors and flow injection analysis.

Combining flow injection analysis with a biosensor is a novel biosensing process which has allowed speedy and accurate analysis. Diagnostic analysis is the most important application for biosensing flow injection analysis, but other applications include bioprocess monitoring, analysis of food and agricultural products, as well as environmental analysis. In addition, the analysis of compounds, such as explosives and abused drugs, and monitoring of Salmonella, the microorganism that causes food poisoning, have been reported.

Animals↗
PubMed1992

Expression of a functional neisserial fbp gene in Escherichia coli.

The ability to acquire iron from a human host is a major determinant in the pathogenesis of Neisseria gonorrhoeae and Neisseria meningitidis. Pathogenic Neisseria spp. do not synthesize siderophores and instead express a receptor-mediated, high-affinity iron acquisition system in the iron-restricted environment of its host. A ferric-iron-binding protein (Fbp) of Neisseria spp. is also iron-regulated and may play a central role in this novel iron-uptake system. To define the physical properties of Fbp further, we used polymerase chain reaction to synthesize DNA fragments containing the fbp structural gene with and without the sequence encoding the Fbp leader peptide. These fragments were ligated into pUC13 to create in-frame fusions with the alpha peptide of lacZ. The expression of Fbp was under the control of the lacZ promoter. Both fusion clones produced Fbp in large amounts, facilitating the purification of quantities of Fbp sufficient for elucidating the biochemical, immunologic, and functional properties of this protein.

Amino Acid Sequence↗
PubMed1992

Altered-function mutations of the transcriptional regulatory gene virG of Agrobacterium tumefaciens.

Three point mutations were isolated in the Agrobacterium tumefaciens virG gene by screening for vir gene expression in the absence of added phenolic inducing compounds. All three mutations were localized in the predicted amino-terminal phosphoryl receiver domain of the protein. One mutant (N54D) bypasses the requirement for VirA and phenolic inducers both for transcriptional activation of all tested vir promoters and for plant tumorigenesis. This mutant also activates vir gene expression efficiently at neutral pH, indicating that the step in induction that is normally stimulated by acid pH occurs before or during VirG phosphorylation. The other two mutants (M13T and H15R) require VirA for activity but are sensitized to low levels of inducing stimuli.

Acetophenones↗
PubMed1992

Two cellular proteins bind specifically to a purine-rich sequence necessary for the destabilization function of a c-fos protein-coding region determinant of mRNA instability.

The c-fos proto-oncogene mRNA is rapidly degraded within minutes after its appearance in the cytoplasm of growth factor-stimulated mammalian fibroblasts. At least two functionally independent sequence elements are responsible for the lability of c-fos mRNA. One of these determinants is located within a 0.32-kb sequence present in the protein-coding region. We demonstrate by gel mobility shift experiments and UV cross-linking that at least two protein factors specifically interact with a 56-nucleotide purine-rich sequence located at the 5' end of the 0.32-kb coding region determinant of mRNA instability (CRDI). One protein is predominantly associated with the polysomes, while the other is detected in the post-ribosomal supernatant. Sequence comparison of members of the fos gene family revealed that the high purine content of the protein-binding region is conserved through evolution. Deletion of this region from the 0.32-kb CRDI severely impedes its function as an RNA-destabilizing element. Our results suggest that binding of the two proteins to the purine-rich sequence may participate in the rapid mRNA decay mediated by this 0.32-kb c-fos CRDI.

3T3 Cells↗
PubMed1992

U-rich sequence-binding proteins (URBPs) interacting with a 20-nucleotide U-rich sequence in the 3' untranslated region of c-fos mRNA may be involved in the first step of c-fos mRNA degradation.

Rapid decay of the c-fos transcript plays a critical role in controlling transforming potential of the c-fos proto-oncogene. One of the mRNA instability determinants is a 75-nucleotide AU-rich element (ARE) present in the 3' untranslated region of the c-fos transcript. It appears to control two steps in the process of c-fos mRNA degradation: removal of the poly(A) tail, which does not require the AUUUA motifs, and subsequent degradation of deadenylated mRNA, which appears to be dependent on the AUUUA motifs. In this study, we report the identification of four U-rich sequence binding proteins (URBPs) that specifically interact with a 20-nucleotide U-rich sequence within the c-fos ARE. Gel mobility shift assay and competition experiments showed that these protein factors form three specific band-shifted complexes with the c-fos ARE. Binding activity of one of the protein factors, a 37-kDa protein, is significantly affected by serum induction and by pretreatment of cells with drugs known to stabilize many of the immediate-early gene mRNAs. Combining UV cross-linking with a new approach, designated sequential RNase digestion, we were able to better determine the molecular masses of these cellular proteins. The binding sites for the four proteins were all mapped to a 20-nucleotide U-rich sequence located at the 3' half of the c-fos ARE, which contains no AUUUA pentanucleotides but stretches of uridylate residues. Single U-to-A point mutations in each of the three AUUUA motifs within the c-fos ARE have little effect on formation of the mobility-shifted complexes. Our data indicate c-fos ARE-protein interaction involves recognition of U stretches rather than recognition of the AUUUA motifs. We propose that UTBP binding may be involved in the first step, removal of the Poly(A) tail, in the c-fos ARE-mediated decay pathway.

3T3 Cells↗
PubMed1992

[Jump flap with pedicle containing superficial epigastric artery for treatment of exposed cranium after electric burn. Report of 9 cases].

Nine patients with denuded cranium after electric burn were treated by using jump flaps with pedicle containing the superficial epigastric artery. The pedicle flap was first transplanted to the burned area on the wrist, and then retransplanted to the cranial defect. It was successful in all cases. The healing time was only one half of that for the traditional method consisting of multiple trephinings through the outer table and then autoskin grafting on the granulations. It also created a better ground for hair grafting later on. Comparing with free flaps or scalp flaps, it was easier to operate and more reliable in blood supply.

Adolescent↗
PubMed1992

[Flow cytometric analysis of DNA in esophageal cancer].

Malignancy is the first of the ten leading causes of death in Taiwan area, however, since 1978, esophageal cancer is on the first ten causes of malignancy. Esophageal cancer is an aggressive neoplasm with a generally poor prognosis. This is usually related to the advanced stages of the neoplasm at presentation and at diagnosis. In this study, the DNA content in tumor was analyzed by flow cytometry, and compared it with clinical- pathological data, especially the survival time. All thirty seven cases (36 male, 1 female, mean age: 56.5 +/- 10.3 y/o) received operation at Kaohsiung Medical College Hospital in the past 11 years and 29 cases (27 male, 2 female, mean age: 62.2 +/- 9.6 y/o) proved to be esophageal cancer by endoscopic biopsy were assayed in this study. The formalin fixed-paraffin embedded block is used to analyze DNA content by flow cytometry. After comparing these results with clinical-pathological data, there were no significant difference in sex, age, duration, tumor location and length. However, there is a significant correlation between ploidy and tumor cell differentiation, that is, most of the diploid cells were well differentiated while most of the aneuploid cells were poorly differentiated. The median survival time of diploid cases was 325 days which was longer than the 277 days in aneuploid group, but there was no significant difference between these two groups. The same result was noticed in DNA index. Multiple variables analysis of prognostic factors disclosed that there were significant difference in correation with age tumor location tumor length, and whether there was combined radiotherapy and operation. But there were no significant relationship between survival and DNA ploidy DNA index distant metastasis surrounding tissue invasion sex duration and tumor cell differentiation. These data suggest that DNA folw cytometry analysis alone, may not provide a sueful biologic basis for the variable prognosis seen with esophageal tumors.

Aged↗
PubMed1992

Monoclonal gammopathies and the related autoimmune manifestations in Taiwan.

A total of 50,000 patients were surveyed for the presence of monoclonal immunoglobulins during the past two decades. There were 411 cases of monoclonal gammopathies including 243 cases of plasma cell neoplasms and 168 cases of secondary plasma-cell dyscrasia. Among the 227 cases of multiple myeloma and Waldenström's macroglobulinemia, there were 49.3% IgG class, 22.9% IgA class, 9.7% IgM class and 13.2% light chain type. In addition, there were 1.3% of nonexcretory myeloma including an IgM type. A relatively high frequency (4.8%) of IgD M-proteins was detected but heavy chain disease was not encountered in the present series. Purified M-components from patients with possible autoimmune manifestations were subjected to immunofluorescence studies. Autoimmune activity of M-proteins was found in a patient of Waldenström's macroglobulinemia with peripheral neuropathy, and another patient of cryofibrinogenemia with recurrent purpura and gangrene. In conclusion, a high frequency of IgD myeloma is found in Chinese patients of this area. M-components may have autoimmune activity resulting in unusual clinical manifestations.

Adolescent↗
PubMed1992

Congenital bronchoesophageal fistula in the adult: a case report.

The case of a 50-year-old woman with congenital bronchoesophageal fistula is presented. The patient had symptoms of hemoptysis provoked by ingestion of liquids for 2 years. A barium swallow examination showed a bronchoesophageal fistula communicating between the middle third of the esophagus and right intermediate bronchus. An orifice of the fistula at the esophagus was revealed by esophagoscopy. The clinical and operative features and diagnosis of congenital origin are discussed.

Bronchial Fistula↗
PubMed1992

Response of left ventricular ejection performance following balloon valvuloplasty in patients with mitral stenosis.

In order to see if any change of left ventricular ejection performance (LEVP) would occur after successful balloon mitral valvuloplasty (BMV), a prospective study on echocardiography and calibrated carotid pulse tractings was performed two days before, two days and then six months after BMV in 24 patients with pure rheumatic mitral stenosis (MS). Echocardiographic parameters representing preload i.e. end-diastolic volume index (EDVI); afterload i.e. end-systolic wall stress (ESS), and the indices of LVEP i.e. ejection fraction (EF), fractional shortening, rate-corrected velocity of circumferential shortening (VCFc) and a ratio of ESS over end-systolic volume index (ESS/ESVI) were measured. A group of 66 normal subjects was used to establish the 95% confidence interval of the echo parameters. The incidence of depressed LVEP in MS patients was about 21% when measured by load-independent index i.e. ESS/ESVI. In the MS group, 7 out 24 (29%) patients achieved an increased cardiac index after BMV. Six (25%) MS patients showed an EF below 95% confidence interval of control (less than 55%) before BMV and, of these 6, only 3 patients increased their EDVI after the BMV. Those who showed an EF greater than or equal to 55% before BMV gave no change in their preload (EDVI) after the BMV. Only one MS patient showed high afterload (ESS) both before and after BMV. However, the ESS/ESVI showed insignificant improvement (p = 0.055) after BMV. It was therefore concluded that (1) a depressed LVEP is frequently seen in patients with MS; (2) LVEP can be improved by BMV in some (21%) patients with MS, and the improvement is not related to the change of preload or afterload but more likely secondary to an increased myocardial contractility.

Adult↗
PubMed1992

Surgical treatment of metastatic lung tumor.

Since the first pulmonary resection for metastatic cancer of the lung in 1939, the following procedure can now be offered to any patient who meets these criteria: 1. a controlled primary tumor, 2. resectable lung lesion, 3. unavailability of a better treatment and 4. a good surgical candidate. From 1982 to 1992, there were 42 patients who underwent an operation for pulmonary metastasis at the Taichung Veterans General Hospital. Their cumulative 3-year and 5-year survival rates were 35% and 25% respectively. The overall estimated median survival time was 23.1 months. The overall operative mortality was 2.4% (1/42). We analyzed the effect of different types of primary tumors, the disease-free interval, and the number of lesions on patient survival. In our series, we concluded that none of the above had an effect on the therapeutic results.

Adolescent↗