Biomedical subjects

M R Chen

Publications and source records attributed to M R Chen.

At least 19 recordsLinked to original sources

PubMed2001

Use of bacterially expressed EBNA-1 protein cloned from a nasopharyngeal carcinoma (NPC) biopsy as a screening test for NPC patients.

EBV serological tests have been used for many years as accessory diagnostic predictors of nasopharyngeal carcinoma (NPC). To increase the sensitivity and specificity of the NPC detection rate, a novel enzyme-linked immunosorbent assay (ELISA) was established using a bacterially-expressed GST-EBNA-1 protein, containing the EBNA-1 sequence cloned from an NPC patient. Serum samples were collected from age- and gender-matched patients with NPC, community control subjects and hospital control patients and tested using this ELISA. The positivity rates were 78.7% (247/314) in NPC, 11.5% (28/244) in hospital controls and 3.8% (10/263) in the community control group. These serum samples were also tested for IgA anti-VCA antibodies and their ability to neutralize EBV DNase and the sensitivities of the anti-VCA antibody and DNase-neutralization tests also were analyzed. The optimum combination is VCA plus EBNA-1, which can identify 92.5% (287/310) of NPC patients, and shows a specificity of 92.7% (242/261) for normal individuals.

Antibodies, Viral↗

PubMed2001

Floating the raft hypothesis: the roles of lipid rafts in B cell antigen receptor function.

The initiation of antibody responses to foreign antigens requires that B cells receive and integrate a variety of signals through an array of cell surface receptors including the B cell antigen receptor (BCR) as well as a number of essential coreceptors. Recent evidence indicates that cholesterol-rich plasma membrane microdomains, referred to here as lipid rafts, serve as platforms for BCR signaling and trafficking in B cells. The existence of rafts suggests a previously unappreciated level of organization at the B cell surface that may explain, at least in part, how BCR signaling is coordinated. Here the current evidence that lipid rafts play a key role in B cell responses is reviewed.

Antigens↗

PubMed2001

Combined atrial and arterial switch operations for congenitally corrected transposition.

Conventional repair of congenitally corrected transposition of the great arteries (CCTGA) is directed at eliminating the associated defects and leaves the right ventricle in a systemic position. The long-term outcome of this procedure may involve deterioration of right ventricular function with tricuspid regurgitation and failure of the conduction system. We describe two consecutive patients with CCTGA, one of whom had apicocaval juxtaposition. The patients were aged 19 and 16 months, respectively, and both underwent a combination of atrial and arterial switch. These are the first two reported cases of successful completion of this type of operation in Taiwan. Our review of previously reported cases suggested that no significant difference exists in the outcome of patients with this condition who undergo either arterial switch or Rastelli-type repair plus atrial redirection. However, reported patients who underwent anatomic repair had lower early mortality, late mortality, and incidence of complete heart block than those who underwent conventional repair. The present two cases and our review of the literature suggest that, among patients with apicocaval juxtaposition, 1) Mustard operation is optimal for patients with small atrial volume; 2) one-and-one-half ventricular repair may be helpful to the outcome, especially when treatment is combined with Rastelli-type repair; and 3) excellent access to the ventricular septal defect through the tricuspid valve is afforded via a left atriotomy. From the present two cases and our review of the literature, we conclude that anatomic repair is superior to conventional repair of CCTGA in terms of protection against dysfunction and failure of the anatomic right ventricle, tricuspid valve, and conduction system. Long-term follow-up is mandatory.

Cardiac Surgical Procedures↗

PubMed2001

Modified arterial switch operation by sharing the common wall between the great arteries.

BACKGROUND: Suprapulmonary stenosis and coronary arterial obstruction still remain as problems after an arterial switch operation (ASO). We used a modified ASO applying the common wall and in situ transfer techniques to improve the current procedure. METHODS: From October 1996 to December 1997, 11 babies aged 6 days to 3 months with transposition of the great arteries underwent a modified ASO which included sharing the common wall between the great arteries until above the anterior neoaortic suture-line for coronary and pulmonary artery reconstruction. Coronary arteries were of usual type in three cases, juxtacommissural origin in five, and a high takeoff in one; all were redirected almost in situ. RESULTS: There was no early death (< 30 d), coronary or bleeding problems. One late death occurred after a repeat surgery for suprapulmonary stenosis. This was caused by upward stretching of the left pulmonary artery, which was placed above the high left-sided neoaortic anastomosis for in situ transfer of the high takeoff coronary arteries. Intraluminal growth of the adventitia also contributed to suprapulmonary stenosis, which decreased significantly when the common wall adventitia was cleaned in the last two cases we operated on. Ten patients were doing well at follow-up (30.9 +/- 5.2 mo). CONCLUSIONS: This modified ASO by common wall and in situ transfer might avoid coronary kinking and lessen the chance of postoperative bleeding. To avoid suprapulmonary stenosis, common wall adventitia inside the pulmonary pathway should be cleaned, and the left and right pulmonary arteries should also be kept in situ as possible as in coronary redirection.

Humans↗

PubMed2001

Valveless outflow reconstruction using autologous tissue as a posterior wall for pulmonary atresia with ventricular septal defect.

BACKGROUND AND PURPOSE: Reoperation is inevitable for some patients with pulmonary atresia who receive a heterograft or homograft in a primary Rastelli operation. Nonetheless, the need for reoperation in patients with classic Fallot's tetralogy who have undergone total correction with a transannular patch is unusual. We sought to change pulmonary atresia into Fallot's tetralogy and used a transannular patch instead of the conventional Rastelli operation. PATIENTS AND METHODS: Valveless outflow direct reconstruction was performed on 10 consecutive patients with pulmonary atresia and ventricular septal defect between August 1997 and 1999. Patient ages ranged from 1.3 to 11.5 years. A Blalock-Taussig shunt was previously constructed in four of these patients and a central shunt was constructed in five. The major aortopulmonary collateral arteries were occluded in one patient by repeated coil embolization after the central shunt. The strategy was to connect the right ventriculotomy with the pulmonary arteries directly, even if there was a gap with a long atretic cord. In patients with a previous central shunt covered with a Gore-Tex membrane, the reactive visceral pericardium over the in situ tissue (the left atrium, right ventricle, or aorta) was used as the autologous posterior wall. Thus, only autologous, fresh pericardium without a valve was used to cover the anterior part of the right ventricular outflow tract, as in the repair of classic Fallot's tetralogy with a transannular patch. RESULTS: There was no mortality, and the postoperative central venous pressure was low in all patients. No gradient was noted across the right ventricular outflow tract. Follow-up echocardiography revealed a competent tricuspid valve with mild pulmonary regurgitation in all patients. CONCLUSIONS: The results of this study suggest that valveless outflow direct reconstruction provides adequate pulmonary circulation without hypertension in pulmonary atresia patients with a ventricular septal defect if the tricuspid valve is competent.

Child, Preschool↗

PubMed2000

Modified arterial switch operation by spiral reconstruction of the great arteries in transposition.

BACKGROUND: Spiral relationship of the normally related great arteries (SRGA) has never been reconstructed in an arterial switch operation. METHODS: From March 1998 to April 1999, 9 consecutive cases of transposition of the great arteries (TGA) family (from 2 days to 1.6 years old) underwent arterial switch operations with SRGA at our hospital. Two had a congenitally corrected TGA (plus atrial redirection). Lecompte maneuver was not used in all. The posterior wall of pulmonary trunk was not divided but three were reattached, two of whom had had previous pulmonary trunk banding. Thus the wall was shared between the great arteries facing each other. RESULTS: All survived the operation. Supraaortic stenosis was balloon-dilated in 2 cases of early series, but technical modifications later were able to avoid it. Angiogram showed smooth flow into SRGA without upward and anterior tilting of the pulmonary bifurcation. All great and coronary arteries were patent. All were doing well on follow-up (16.5 +/- 4.2 months). CONCLUSIONS: We concluded that the techniques to relocate the coronary arteries using common wall and in situ switch could also be applied to pulmonary arterial reconstruction, so that SRGA can be resumed in TGA.

Anastomosis, Surgical↗

PubMed2000

A novel EBNA-1 tag system for high level expression and efficient detection of fusion proteins in vitro and in vivo.

A highly specific monoclonal antibody, which recognises an epitope between amino acids (aa) 408 and 446 of EBNA-1, was found to immunoprecipitate this protein with great efficiency. By adding a 39-aa tag, the BGLF4 protein product of EBV was shown to express in the cytoplasm of transfected cells. This EBNA-1 tag could be used for the detection of specific protein expression by immunoblotting, immunofluorescence and, especially, immunoprecipitation assays. A plasmid vector encoding this EBNA-1 tag sequence was therefore designed for efficient expression both in vitro and in vivo. The efficient translational start signal of black beetle virus (BBV) was placed under the control of the SV40 or T7 promoters, and the beta-globin splicing signal used to enhance the transportation of mRNA from the nucleus to the cytoplasm.

Antibodies, Monoclonal↗

PubMed2000

A protein kinase activity associated with Epstein-Barr virus BGLF4 phosphorylates the viral early antigen EA-D in vitro.

The Epstein-Barr virus (EBV) open reading frame BGLF4 was identified as a potential Ser/Thr protein kinase gene through the recognition of amino acid sequence motifs characteristic of conserved regions within the catalytic domains of protein kinases. In order to investigate this potential kinase activity, BGLF4 was expressed in Escherichia coli and the purified protein was used to generate a specific antiserum. Recombinant vaccinia virus vTF7-3, which expresses the T7 RNA polymerase, was used to infect 293 and 293T cells after transient transfection with a plasmid containing BGLF4 under the control of the T7 promoter. Autophosphorylation of the BGLF4 protein was demonstrated using the specific antiserum in an immune complex kinase assay. In addition, EBNA-1-tagged BGLF4 and EBNA-1 monoclonal antibody 5C11 were used to demonstrate the specificity of the kinase activity and to locate BGLF4 in the cytoplasm of transfected cells. Manganese ions were found to be essential for autophosphorylation of BGLF4, and magnesium can stimulate the activity. BGLF4 can utilize GTP, in addition to ATP, as a phosphate donor in this assay. BGLF4 can phosphorylate histone and casein in vitro. Among the potential viral protein substrates we examined, the EBV early antigen (EA-D, BMRF1), a DNA polymerase accessory factor and an important transactivator during lytic infection, was found to be phosphorylated by BGLF4 in vitro. Amino acids 1 to 26 of BGLF4, but not the predicted conserved catalytic domain, were found to be essential for autophosphorylation of BGLF4.

Amino Acid Sequence↗

PubMed2000

Polymorphism of transmembrane region of MICA gene and Kawasaki disease.

Kawasaki disease is a febrile disease of children complicated with vasculitis of the coronary arteries and potential aneurysm formation. It has been recognized worldwide and appears to be increasing in frequency. Studies have found that Kawasaki disease is associated with major histocompatibility complex (MHC) class I B antigens. The MHC-class-I-chain-related gene A (MICA) is located near HLA-B. It has a triplet repeat microsatellite polymorphism in the transmembrane region. We investigated the microsatellite polymorphism in children with Kawasaki disease and controls. Seventy children (46 boys), age at diagnosis 1.68 +/- 1.69 years, with Kawasaki who were treated with aspirin as well as intravenous gamma-globulin were enrolled. Control subjects consisted of 154 children (87 boys), age 2.81 +/- 2.12 years. Phenotype frequency of allele A4 in patients with aneurysm formation was significantly lower than in patients without aneurysms [relative risk (RR) = 0.06, 95% confidence interval (CI) = 0.01-0.48, p = 0.00469, pc = 0.0232] and showed a similar tendency when compared with controls. Gene frequency of allele A4 was also significantly lower in patients who developed aneurysms than in patients who did not (RR = 0.07, 95% CI = 0.01-0.57, p = 0.0057, pc = 0.0282). Gene frequency of allele A5 showed a tendency to be higher in patients who developed aneurysms than in controls (RR = 2.35, 95% CI = 0.98-5.63, p = 0.0486, pc = 0. 220). Allele A5.1 tended to be negatively associated with Kawasaki disease (RR = 0.57, 95% CI = 0.35-0.93, p = 0.022, pc = 0.105). Our study showed that allele A4 was negatively associated with coronary aneurysm formation in Kawasaki disease. This suggests that allele A4 protects the children with Kawasaki disease from developing coronary aneurysms after aspirin and gamma globulin therapy.

Alleles↗

PubMed2000

Occlusion of azygos vein via direct percutaneous puncture of innominate vein following cavopulmonary anastomosis.

A 2-year-10-month-old boy was diagnosed with a complex congenital heart disease: right atrial isomerism, left superior vena cava (LSVC), complete atrioventricular septal defect, secundum type atrial septal defect, transposition of the great arteries with pulmonary atresia, patent ductus arteriosus, absence of a right superior vena cava (RSVC), and dextrocardia. He had received a left Blalock-Taussig (BT) shunt at the age of 3 months and a left bidirectional Glenn shunt one year after BT shunt. Progressive cyanosis was noted after the second operation and cardiac catheterization showed a functional Glenn shunt with an engorged azygos vein, which was inadvertently skipped for ligation. Because of the absence of RSVC, transcatheter occlusion of the azygos vein was performed successfully via direct puncture of the innominate vein.

Anastomosis, Surgical↗

PubMed2000

Complete myocardial revascularization using only pedicled arterial conduits in Kawasaki disease.

A 16-year-old boy with Kawasaki disease suffered from progressive angina and exercise intolerance for 1 year. Coronary angiography showed 60% stenosis of the left main coronary artery, a calcified aneurysm with total occlusion at the proximal left anterior descending artery (LAD), and another aneurysm with total occlusion at the middle portion of the right coronary artery. Aortocoronary bypass was done with the left internal mammary artery (IMA) anastomosed to the first obtuse marginal branch, the right IMA to the distal LAD, and the right gastroepiploic artery to the posterior descending artery. Graft patency was documented by follow-up coronary angiography 1 month after surgery. During follow-up, his rapid improvement led to an upgrade from New York Heart Association functional class III to class I. The results of the present case suggest that complete myocardial revascularization using arterial conduits in patients with Kawasaki disease with coronary artery occlusion is safe and effective.

Adolescent↗

PubMed2000

Comparative study of timolol gel versus timolol solution for patients with glaucoma.

BACKGROUND: The timolol gel was developed for the simplification of multi-dose medications for glaucoma patients. This gel can be used once per day instead of twice per day of the aqueous form. It is necessary to understand the clinical effects of intraocular pressure maintained in glaucoma by there two forms of timolol. METHODS: Fifty-two eligible patients were included and completed the 12-week study. In this randomized, open-label, two-period crossover study design, patients received either the gel form of 0.5% timolol once daily or the aqueous form of 0.5% timolol twice daily for the first 6 weeks, then crossed over to the other treatment form for the remaining 6 weeks. Intraocular pressure was measured at baseline, week 6 and week 12 at the end of the treatment period. The incidences of all the adverse events were recorded and summarized in each follow-up visit. RESULTS: No statistically significant difference in intraocular pressure was observed between the two different control treatment groups (p>0.05). However, stickiness and transient blurred vision was reported more often by patients using the gel form than the aqueous form of timolol. CONCLUSIONS: The gel form of 0.5% timolol used once daily offers a new alternative that is probably more convenient than the aqueous form of 0.5% timolol given twice daily in maintaining the intraocular pressure of patients with glaucoma.

Adrenergic beta-Antagonists↗

PubMed1999

The major immunogenic epitopes of Epstein-Barr virus (EBV) nuclear antigen 1 are encoded by sequence domains which vary among nasopharyngeal carcinoma biopsies and EBV-associated cell lines.

Epstein-Barr virus (EBV) nuclear antigen 1 (EBNA-1) is a protein expressed consistently in EBV-infected cells and EBV-associated malignant tissues. A panel of monoclonal antibodies (MAbs) was generated against the C terminus of EBNA-1 and evaluated for the detection of EBNA-1 in different cell lines. The epitopes recognized were mapped. Since sequence variations of EBNA-1 have been reported in nasopharyngeal carcinoma (NPC) tissues and in infected healthy individuals, the ability of these MAbs to recognize a recombinant protein derived from an NPC biopsy was also analysed. MAb 4H11 appeared to react with EBNA-1 sequences from different sources, whereas MAbs 5C11, 5F12 and 8F6 failed to recognize a recombinant EBNA-1 protein cloned from an NPC patient. Using different recombinant EBNA-1 fragments in an immunoblot format, this study demonstrates that the domain bounded by amino acids 408 and 498 is very immunogenic in mice in that epitopes in this region are recognized by various MAbs. Amino acid sequences of EBNA-1 were also deduced from nucleotide sequences amplified from three Burkitt's lymphoma cell lines, two spontaneous lymphoblastoid cell lines, two NPC biopsies and one NPC hybrid cell line, NPC-KT, and compared to the sequence from B95-8. The amino acid sequence of EBNA-1 in Akata is almost identical to that in an NPC biopsy, except for amino acid 585. The results of this study indicate that the immunogenic epitopes of EBNA-1 are highly variable.

Amino Acid Sequence↗

PubMed1998

Physical association between the EBV protein EBNA-1 and P32/TAP/hyaluronectin.

Epstein-Barr virus (EBV) nuclear antigen-1 (EBNA-1) is a protein expressed constitutively during EBV latency. It is required to support the replication of the EBV genome once per cell cycle via the latent origin of replication, oriP. EBNA-1 also can activate transcription through binding to the family repeats of oriP. We wished to identify candidate cellular protein(s) that may interact with EBNA-1 and mediate these functions. A 32-kd protein was co-immunoprecipitated with EBNA-1 from 293 cells using a monoclonal antibody EBNA.OT1x. The regions of EBNA-1 which interact with this protein were studied using two deletion clones and mapped to EBNA-1 residues 1-102 and 325-357. Deletion of this region was shown previously in a mutant of EBNA-1 which had dominant-negative effects on both DNA replication and transactivation assays. The 32-kd protein was found to react with a polyclonal antiserum against P32/TAP (HIV Tat associated protein), which is known to interact with other RNA binding proteins and the RNA splicing factor SF2. The function of P32 was therefore proposed to involve RNA processing. In addition, this molecule was recently identified as hyaluronectin, which binds hyaluronic acid. Because several reports documented that intracellular hyaluronic acid can potentially affect cell proliferation, the association between EBNA-1 and P32/TAP/hyaluronectin may help the maintenance of episomal viral DNA within proliferating cells.

Animals↗

PubMed1998

Atrial flutter in the neonate and early infancy.

Atrial flutter is a rare arrhythmia in the neonate and early infancy. We retrospectively reviewed the clinical presentations, treatment and outcome of seven patients who presented clinically with atrial flutter. The age of onset ranged from 1 day to 3 months. Atrial flutter was diagnosed in the first 3 days of life in 4. Three cases presented as atrial flutter with 2:1 atrioventricular conduction and the remaining 4 with variable AV block. Heart failure was present in 3 patients and 6 patients showed normal intracardiac structure on echocardiography. Electrical cardioversion was attempted as the first treatment in 4 cases, followed by digoxin in three of the four. Digoxin was given as an initial therapy in 2 patients. One patient recovered spontaneously without treatment. In the 6 patients who received therapy, 5 converted to normal sinus rhythm within 2 days. The remaining patient had ventricular ectopic beats for about 4 months. Only 2 cases were maintained on oral digoxin for at least 4 months after discharge. No patient had a recurrence of atrial flutter during the follow-up period which ranged from 6 months to 7 years. We conclude that there is a good long-term prognosis for atrial flutter in the neonate. Digoxin and DC cardioversion may be effective as initial therapy. Long-term digoxin prophylaxis after conversion to sinus rhythm may be not necessary.

Age of Onset↗

PubMed1997

Frequency of associated anomalies in congenital hypoplasia of depressor anguli oris muscle: a study of 50 patients.

Aside from congenital heart disease, anomalies associated with unilateral hypoplasia of the depressor anguli oris muscle have not been well-documented in large series. We evaluated the associated anomalies in 50 infants or children with this disorder (male:female = 2:1) and found accompanying anomalies in 35 (70%) of 50 cases. They included anomalies of the head and neck (48%), heart (44%), skeleton (22%), genitourinary tract (24%), central nervous system (10%), gastrointestinal tract (6%), and miscellaneous minor anomalies (8%). Nearly half of our cases (22/50) had at least 2 associated systemic anomalies. Failure to thrive and psychomotor retardation were found in 5 (10%) and 3 (6%) patients, respectively, on follow-up. Three infants died neonatally of severe heart disorders, and the other one died of central nervous system anomalies. The above findings indicate that a thorough search for associated anomalies, particularly in the cardiovascular system, should be performed in all newborns with asymmetric crying face.

Abnormalities, Multiple↗

PubMed1997

Neonatal tuberous sclerosis with cardiac rhabdomyomas presenting as fetal supraventricular tachycardia.

A case of fetal tuberous sclerosis with multiple intracardiac rhabdomyomas exhibited persistent supraventricular tachycardia. The tachycardia was terminated by the use of cardiac version. The largest tumor almost occluded the right ventricular inlet portion. The obstruction was relieved after surgical removal of the largest tumor. No arrhythmia was noted after 3 months of follow-up.

Adult↗

PubMed1996

Angiographic evidence of long-axis rotation in addition to short-axis aortopulmonary rotation: its implication in transposition of the great arteries.

To assess the pattern of aortic sinus in varied aortopulmonary rotations and its clinical implications, three aortic sinuses at the diastolic phase in true lateral view are identified in 53 angiograms of complete transposition of the great arteries recorded between 1988 and 1993. The patients with the high takeoff of the coronary arteries found at surgery and in the literature were selected for additional investigation. Six regions were defined on the horizontal plane. From left anterior 89 degrees to 61 degrees, the non-facing sinus moved toward the anterior aspect (one patient). From left anterior 60 degrees to left anterior 1 degree, the left-hand sinus moved gradually from an anterior toward a posterior location (two patients). From directly anterior 0 degree to right anterior 59 degrees, the right-hand sinus moved from posterior toward an anterior position (30 patients). From right anterior 60 degrees to right posterior 105 degrees, the non-facing sinus moved posteriorly (20 patients). On approaching directly anterior 0 degree and toward right anterior 60 degrees, the left-hand sinus was the lowest in anterior transposition of the great arteries instead of the non-facing sinus, as in left anterior 90 degrees and in posterior transposition of the great arteries. High takeoff occurred commonly above the lowest left-hand sinus in anterior transposition of the great arteries (2 cases here and 5 in the literature, 100%). In conclusion, aortopulmonary rotations about the short and long axes were both evident on identification of the aortic sinus in various rotations. The aortic sinus did not rotate along the long-axis in anterior transposition of the great arteries, thus making the left-hand sinus, the lowest of this group, vulnerable to the high takeoff of the coronary arteries in anterior transposition of the great arteries.

Aorta↗