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Biomedical subjects

C C Wang

Publications and source records attributed to C C Wang.

At least 325 records · Page 18Linked to original sources
PubMed1996

Identification of cis-acting signals in the giardiavirus (GLV) genome required for expression of firefly luciferase in Giardia lamblia.

Giardiavirus (GLV) is a 6,277-bp double-stranded RNA virus of Giardia lamblia, one of the earliest eukaryotic divergents from the prokaryotes. Our previous success in GLV-mediated transfection of G. lamblia has provided an effective way of monitoring the mechanisms underlining GLV gene replication and mRNA translation in this organism. Here we have investigated the cis-acting signals in the GLV genome that regulate replication, transcription, and translation of an inserted firefly luciferase gene in GLV-infected G. lamblia. By modifying the two terminal regions of a full-length GLV cDNA clone used to flank a luciferase gene, various in vitro chimeric transcripts were generated and introduced into GLV-infected G. lamblia via electroporation. Expression of luciferase (+) strand and (-) strand RNAs in the transfected cells was monitored and the luciferase activity assayed. The results indicated that the 5'-untranslated region (UTR) of 366 nt and the 3'-terminal 2,022 nt of the viral transcript are both needed for optimal expression of the two RNA strands. Although the entire 5'-UTR is needed for the chimeric mRNA synthesis, both the primary sequence and the secondary structure at the 3' end of GLV transcript are essential for the synthesis of (-) strand RNA. When the 5' end of GLV transcript was extended 265 nt into the capsid protein open reading frame and fused with that of luciferase, there was no change in the level of luciferase chimeric RNA, but a 5,000-fold increase of luciferase activity was observed that may be attributed to an enhanced translational efficiency of the chimeric mRNA in G. lamblia.

Animals↗
PubMed1996

Altered fractionated radiation therapy for head and neck carcinomas--A Massachusetts General Hospital experience.

This paper discusses the various forms of altered fractionated radiation therapy programmes which were used in the past and at present. Treatment programmes employing large fraction sizes and prolonged treatment course result in severe late complication of the normal tissues and inferior local tumour control respectively, and are no longer advised. The current radiobiologic concepts of altered fractionationated treatment are briefly discussed. The experiences of using accelerated hyperfractionated radiation therapy programme for the treatment of oropharyngeal and laryngeal carcinomas at the Massachusetts General Hospital (MGH) from 1979 through 1994 are presented. The programme consists of 1.6 Gy/f twice-daily (BID) for approximately 67.2-70.4 Gy in 6 weeks with a short 'break' after the initial 38.4 Gy. The local control and disease specific survival rates after BID are reported related to the various stages of the lesions and compared with historical control of once-daily (QD) radiation therapy at the MGH. The data thus far indicated higher local control and disease specific survival after BID radiation therapy for advanced carcinomas (T2-3 lesions). The therapeutic gains, however, did not occur significantly for early lesions (T1 disease). The importance of the effects of the total doses and total treatment time, related to the treatment outcome, is discussed.

Actuarial Analysis↗
PubMed1996

Bacterial tracheitis: a case report.

An 18-month-old girl was brought to the emergency room of Chang Gung Children's Hospital with inspiratory stridor, suprasternal retractions and imminent respiratory failure. Despite orotracheal intubation, persistent poor air-entry was noted. Flexible bronchoscopy via the endotracheal tube showed a copious amount of mucopurulent secretions in the tracheobronchial tree without any foreign bodies. With vigorous suctioning and antibiotic treatment, she had a rapid recovery. Tracheal aspirates showed a growth of Haemophilus influenzae. Cefamandole was used with good response. In conclusion, although bacterial tracheitis is an uncommon obstructive upper airway disease in children, using a bronchoscope to diagnose and to guide specific therapy can decrease the morbidity and mortality.

Bronchoscopy↗
PubMed1996

Retrograde atrio-His bundle dissociation as a sign indicative of retrograde accessory pathway conduction.

Electrophysiologic study and radiofrequency ablation therapy were performed in a 36-year-old male with Wolff-Parkinson-White syndrome and Ebstein's anomaly. The study disclosed the presence of a posteroseptal accessory pathway and dual atrioventricular (AV) nodal pathways. Retrograde atrio-His bundle (A-H) dissociation was noted during rapid ventricular pacing, in which the atria were activated by retrograde impulse from the accessory pathway with a fixed ventriculo-atrial (VA) interval while the retrograde His bundle potential was visible during the diastolic isoelectric period due to the occurrence of Wenckebach periodicity within the His-Purkinje system. This phenomenon is a useful sign for rapid recognition of the accessory pathway conduction.

Adult↗
PubMed1996

Nasopharyngeal adenoid cystic carcinoma: five new cases and a literature review.

OBJECTIVE: Nasopharyngeal adenoid cystic carcinoma (NACC) is a rare tumour, and its mainstay treatment is different from adenoid cystic carcinoma arising from another head and neck region. In this study, we analyzed 20 cases of NACC with complete clinical information, 5 from Chang Gung Memorial Hospital and 15 from the literature review. RESULTS: The time interval between first symptom and treatment ranged from 2 weeks to 8 years, with a median of 24 months. Compared with usual nasopharyngeal carcinoma, NACC has higher incidence of cranial nerve involvement (55%) and lower incidence of cervical adenopathy (15%). All patients were treated by radiotherapy and 6 patients received surgical treatment. The 5- and 10-year overall survival rates were 78% and 49.5%, respectively. Seven patients developed metastasis to lung or bone. After a minimum of 5 years' follow-up, the local control rate was 45.5% in patients receiving radiation dose > 70 Gy, and 28.6% in those receiving dose < or = 70 Gy, suggesting higher radiation dose is necessary to achieve better local control in NACC.

Adult↗
PubMed1996

Immunohistochemical study of amoeboid microglial cells in fetal rat brain.

The present study examined the expression of different antigens in amoeboid microglial cells (AMC) in fetal rat brain extending from 12 to 20 d postconception (E12-E20) using a panel of monoclonal antibodies which recognised the major histocompatibility complex (MHC) class I (OX-18) and class II (OX-6) antigens, leucocyte common antigen (OX-1), CD4 receptor (OX-35), complement type 3 receptor (OX-42) or macrophage antigens of unknown function (ED1 and ED2). Of the above-mentioned antigens, ED1 and ED2-labelled AMC were observed in the neuroepithelia as early as embryonic day 12 (E12); other antigens were not detected at this stage. At E14, except for MHC class I antigen, all other antigens were expressed by AMC distributed predominantly in the developing white matter. At E16, AMC in the intermediate zone lateral to the striatum were endowed with all the above-mentioned antigens including MHC class I. At E18, the immunoreactivities of AMC stained with OX-6, OX-18, OX-35 and OX-42 antigens were noticeably reduced when compared with those cells at E16. At E20, amoeboid microglial cells exhibited full complement of antigen expression similar to those cells at E16; some of the labelled cells emitted a variable number of cytoplasmic processes. It is suggested that the successive and differential expression of various macrophage related antigens on AMC in fetal brain is related to the specific requirement of local environment in different stages of development.

Animals↗
PubMed1996

Examination of pericardial effusions by cytology and immunocytochemistry.

BACKGROUND: Cytologic examination of pericardial effusions (PE) has been uncommonly reported in the literature. Fewer reports have studied the role of immunocytochemistry in diagnosis of PE. We described our experience, according to cytologic examination and immunocyto-chemical staining of PE. METHODS: Over a four-year period, 50 PE specimens from 36 patients were examined cytologically by Wright-Giemsa stain and/or Papanicolaou stain, at Tri-Service General Hospital. Immunocytochemical stainings were further performed to ensure the cell nature. RESULTS: Eighteen of these patients had benign etiologies; the others suffered from malignant diseases. Sixteen cases, including eight benign and eight malignant, received pericardial biopsy for comparison. Commonly encountered cells in PE with any kind of etiology included neutrophils, lymphocytes macrophages and mesothelial cells. Cancer cells were additionally seen in malignant PE, but not in all cases with cancers. Furthermore, reactive mesothelial cells and macrophages were sometimes not easily distinguished from cancer cells, and reactive lymphocytes frequently mimicked hematopoietic malignancies. Further, the nature of small round tumor cells can hardly be ensured by morphologic examination only. Immunocytochemical studies were successfully used to solve these dilemmas in some suspicious cases. CONCLUSIONS: This study showed that cytology together with clinical information and immunocytochemistry can achieve excellent sensitivity and specificity in identification of malignant PE. The use of immunocytochemistry can even ensure the nature of certain cancers such as small cell carcinoma and B cell lymphoma.

Adult↗
PubMed1996

Clinical isolation of vancomycin-resistant Enterococcus faecalis in Taiwan.

We report the isolation of a vancomycin-resistant strain of Enterococcus faecalis, designated AH803, from a 76-year-old Taiwanese woman with pneumonia and bacteremia. This is the first documented clinical isolation of a vancomycin-resistant enterococcus in Taiwan. AH803 was repeatedly isolated from sputum specimens of the patient. AH803 had a high level of vancomycin (minimal inhibitory concentration, MIC = 512 micrograms/mL) and gentamicin (MIC > 2,000 micrograms/mL) resistance, but was susceptible to teicoplanin (MIC = 8 micrograms/mL) and ampicillin (MIC = 2 micrograms/mL). AH803 was shown by polymerase chain reaction to have the vanA gene, but not the vanB gene. Despite treatment efforts, the patient's condition continued to deteriorate. She requested to be discharged, against medical advice. The patient died at home the following day after discharge.

Aged↗
PubMed1996

Hemorrhage in intracranial epidermoid cyst.

A case of intracranial epidermoid cyst with intracystic hemorrhage is reported. A 63-year-old woman sustained a head injury after a fall; obtundation and ataxia were noted later. Computed tomography revealed a heterogeneous hyperdense lesion in the posterior and middle cranial fossas. Magnetic resonance imaging showed a lesion with increased signal intensity both on T1 and T2 weighted images. Two craniotomies revealed an intracranial epidermoid cyst with about 6 mL of clotted blood. Pathologic study showed hemosiderin-laden macrophages and neovascularity in the cystic wall granulation tissue, which indicated rupture of the cystic wall with intracystic hemorrhage, which later correlated with the diagnostic image findings. The patient tolerated the two operations well and her postoperative course was smooth. She was discharged in good health without obvious neurologic deficits.

Brain Diseases↗
PubMed1995

Identification of the active sites of human and schistosomal hypoxanthine-guanine phosphoribosyltransferases by GMP-2',3'-dialdehyde affinity labeling.

Labeling of human and schistosomal hypoxanthine-guanine phosphoribosyltransferases (HGPRTases) with GMP-2',3'-dialdehyde (ox-GMP) results in nearly complete inactivation of the enzymes. Digestion of the [3H]ox-GMP-modified HGPRTases with trypsin followed by high-performance liquid chromatographic fractionation, partial amino acid sequencing, and mass spectral analysis of the labeled peptides revealed that four peptides from each of the two HGPRTases were labeled with ox-GMP. The conclusion from these studies indicates that two segments of the human enzyme protein, Ser 4-Arg 47 and Ser 91-Arg 100, and one region in the schistosomal enzyme, Gly 95-Lys 133, were labeled by ox-GMP. Since the ox-GMP labeling of human HGPRTase was effectively blocked by either GMP or PRibPP, whereas that of schistosomal HGPRTase was inhibited only by GMP [Kanaaneh, J., Craig, S. P., III, & Wang, C. C. (1994) Eur. J. Biochem. 223, 595-601], the two labeled peptides in human enzyme may be involved in binding to both GMP and PRibPP while the one peptide in schistosomal enzyme may be implicated only in GMP binding. We have also confirmed a previous observation [Keough, D. T., Emmerson, B. T., & de Jersey, J. (1991) Biochim. Biophys. Acta 1096, 95-100] that carboxymethylation of Cys 22 in the human HGPRTase by iodoacetate was inhibited by PRibPP. We also demonstrated that the carboxymethylation of Cys 25 in schistosomal HGPRTase by iodoacetate was specifically blocked by PRibPP. Apparently, the N-terminal regions in both enzymes are involved in PRibPP binding. The fact that ox-GMP labels the N-terminal region in human enzyme but not in schistosomal enzyme and that PRibPP protects against ox-GMP labeling in human enzyme but not in schistosomal enzyme both suggest that the amino-terminal PRibPP-binding site may be in close proximity to the GMP-binding site in human HGPRTase but not in schistosomal HGPRTase. This clear distinction between the active sites of human and schistosomal HGPRTases could be further exploited for potential opportunities for antischistosomal chemotherapy.

Affinity Labels↗
PubMed1995

Modular organization of T4 DNA polymerase. Evidence from phylogenetics.

We describe the use of a phylogenetic approach to analyze the modular organization of the single-chained (898 amino acids) and multifunctional DNA polymerase of phage T4. We have identified, cloned in expression vectors, and sequenced the DNA polymerase gene (gene 43) of phage RB69, a distant relative of T4. The deduced primary structure of the RB69 protein (RB69 gp43) differs from that of T4 gp43 in discrete clusters of short sequence that are interspersed with clusters of high similarity between the two proteins. Despite these differences, the two enzymes can substitute for each other in phage DNA replication, although T4 gp43 does exhibit preference to its own genome. A 55-amino acid internal gp43 segment of high sequence divergence between T4 and RB69 could be replaced in RB69 gp43 with the corresponding segment from T4 without loss of replication function. The reciprocal chimera and a deletion mutant of the T4 gp43 segment were both inactive for replication and specifically inhibitory ("dominant lethal") to the T4 wild-type allele. The results show that phylogenetic markers can be used to construct chimeric and truncated froms of gp43 that, although inactive for replication, can still exhibit biological specificity.

Amino Acid Sequence↗
PubMed1995

Identification of the IMP binding site in the IMP dehydrogenase from Tritrichomonas foetus.

The IMP dehydrogenase from Tritrichomonas foetus has been identified as a potential target for antitritrichomonial chemotherapy. The gene encoding this enzyme was expressed in transformed Escherichia coli, and the recombinant protein was purified to homogeneity with an average yield of 3 mg of protein per liter of bacterial culture. Kinetic characterizations verified that the recombinant enzyme is in the authentic native state. 6-Cl-IMP, an irreversible inhibitor of the enzyme, was found to protect cysteine residue 319 of the enzyme against carboxymethylation by iodoacetamide. Radiolabeled IMP was covalently bound to the enzyme during the enzyme-catalyzed reaction via the formation of a specific adduct with cysteine residue 319. It is thus postulated that the conversion of IMP to XMP catalyzed by the IMP dehydrogenase from T. foetus is mediated by a nucleophilic attack of cysteine-319 in the enzyme protein to IMP at, most likely, its 2-position to facilitate a hydride transfer to NAD, resulting in the formation of a covalent intermediate between substrate and enzyme.

Animals↗
PubMed1995

Adult soft tissue sarcomas of the head and neck treated by radiation and surgery or radiation alone: patterns of failure and prognostic factors.

PURPOSE: To analyze our experience treating soft tissue sarcomas of the head and neck in adults, and to identify patterns of failure and prognostic factors. METHODS AND MATERIALS: The records of 57 patients with Stage M0 disease treated by radiation with or without surgery between 1972 and 1993 were reviewed. Median follow-up time was 4.3 years (range, 1.1-16.8 years). A group of potential prognostic factors was evaluated, including age at diagnosis, sex, initial tumor presentation (primary vs. recurrent), grade, T-stage, direct tumor extension, tumor depth, duration of treatment, and radiation dose. RESULTS: The subset of angiosarcomas (11 out of 57 patients) had a considerably adverse effect on treatment outcome for the total group of sarcomas, with actuarial 5-year overall survival (OS), locoregional control (LRC), and freedom from distant metastasis (FDM) rates being 31%, 24%, and 42%, respectively. In contrast, for the remaining 46 patients with other histopathological tumor types, OS, LRC, and FDM rates were significantly higher (74%, 69%, and 83%, respectively). For this group of patients, significant prognostic factors identified by uni- and multivariate analysis included tumor grade as a predictor of OS and T-stage as a predictor of LRC (p < or = 0.050). Those patients who experienced a locoregional recurrence were at a significantly increased risk of dying (p = 0.004 in a multivariate model). All 17 patients without direct tumor extension to neurovascular structures, bone, contiguous organs, or skin remained free from distant failure. In contrast, 27% of 29 patients with direct extension had developed distant metastases at 5 years. In multivariate analysis, the absence of direct extension was a positive predictor of FDM (p = 0.007) and of OS (p = 0.034). CONCLUSIONS: 1) Angiosarcomas of the head and neck have a considerably poorer prognosis than other soft tissue sarcomas of this site. 2) In addition to tumor grade and size, direct tumor extension may be a useful additional staging parameter. 3) High rates of locoregional failure in the head and neck area, a potential cause of morbidity and death, indicate a need for improved treatment strategies.

Adult↗
PubMed1995

Improved gene expression by a modified bicistronic retroviral vector.

We have previously described the construction of a bicistronic retroviral vector using the picornavirus internal ribosome entry site (IRES), which allows two genes expression simultaneously from a single transcript. This vector transcribes RNA efficiently; however, in some cases the levels of protein production are low. In this report, we further modified the bicistronic vector by abolishing the functional viral gag initiation codon that is retained in the vector at 5' to the first initiation codon of transduced gene. Five different genes, human interleukin 2 (hIL-2), human interleukin 4 (hIL-4), human granulocyte macrophage stimulating factor (hGM-CSF), herpes simplex virus thymidine kinase (HSV-tk) gene, and hepatitis C virus (HCV) core gene (C190), were tested on this modified vector for gene transfer and expression. Our results demonstrated that the new bicistronic vector greatly increased the protein levels when compared with the original one. As the RNA levels and splicing patterns from these two vectors remained similar, the improvement was most likely resulted from the increased translational efficiency.

Animals↗
PubMed1995

Partial characterization of the cytoplasmic domain of human kidney band 3.

The major anion exchanger in type A intercalated cells of the cortical and medullary collecting ducts of the human kidney is a truncated isoform of erythrocyte band 3 (AE1) that lacks the N-terminal 65 residues. Because this missing sequence has been implicated in the binding of ankyrin, protein 4.1, several glycolytic enzymes, hemoglobin, and hemichromes in erythrocytes, we have undertaken examination of the structure and peripheral protein interactions of this kidney isoform. The cytoplasmic domain of kidney band 3, kidney CDB3, was expressed in Escherichia coli and purified to homogeneity. The kidney isoform exhibited a circular dichroism spectrum and Stokes radius similar to its larger erythrocyte counterpart. Kidney CDB3 was also observed to engage in the same conformational equilibrium characteristic of erythrocyte CDB3. In contrast, the tryptophan and cysteine clusters of kidney CDB3 behaved very differently from erythrocyte CDB3 in response to pH changes and oxidizing conditions. Furthermore, kidney CDB3 did not bind ankyrin, protein 4.1, or aldolase, and expression of erythrocyte CDB3 was toxic to its bacterial host, whereas expression of kidney CDB3 was not. Taken together, these data suggest that the absence of the N-terminal 65 amino acids in kidney CDB3 eliminates the major function currently ascribed to CDB3 in erythrocytes, i.e. that of peripheral protein binding. The primary function of residues 66-379 found in kidney CDB3 thus remains to be elucidated.

Anion Exchange Protein 1, Erythrocyte↗
PubMed1995

Independence of the chaperone activity of protein disulfide isomerase from its thioredoxin-like active site.

Protein disulfide isomerase (PDI) alkylated at thiols of the thioredoxin-like -CHC- active sites is devoid of isomerase activity, but its chaperone-like activity to increase the reactivation yield and prevent the aggregation of guanidine hydrochloride-denatured D-glyceraldehyde-3-phosphate dehydrogenase upon dilution is unimpaired. A peptide of 28 amino acids markedly inhibits both the enzyme and the chaperone activities of PDI. The above results indicate that the -CGHC- active site is necessary for the isomerase activity but not required for the chaperone activity of PDI, whereas the peptide binding site is essential for both activities.

Alkylation↗
PubMed1995

Chaperone-like activity of protein disulfide-isomerase in the refolding of rhodanese.

Protein disulfide-isomerase (PDI) in near stoichiometric concentrations promotes reactivation and prevents aggregation of guanidine-hydrochloride-denatured rhodanese during refolding upon dilution. PDI also suppresses aggregation of rhodanese during thermal inactivation. The above-mentioned properties displayed by PDI completely satisfy the definition of chaperone and provide additional evidence to confirm the hypothesis proposed previously [Wang, C. C. & Tsou, C. L. (1993) FASEB J. 7, 1515-1517] that PDI is both an enzyme and a chaperone. Since rhodanese contains no disulfide bonds, the chaperone-like activity of PDI acting on rhodanese is independent of its disulfide-isomerase activity.

Animals↗