Biomedical subjects

M R Chen

Publications and source records attributed to M R Chen.

At least 19 recordsLinked to original sources

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↗

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↗

PubMed1996

Case report: agenesis of the right lung diagnosed by three-dimensional reconstruction of helical chest CT.

Unilateral pulmonary agenesis is extremely rare and the diagnosis can be made by a number of conventional methods. We report two cases: a 16-day-old girl and a 14-year-old girl presenting with tachypnoea in whom three-dimensional reconstruction of helical chest computed tomography was used to demonstrate the complete absence of the carina, right main bronchus and right lung. To our knowledge, these are the first cases of right lung agenesis diagnosed by this method.

Adolescent↗

PubMed1996

Use of bacterially expressed GST/EBNA-1 fusion proteins for detection of antibodies in sera from patients with nasopharyngeal carcinoma and healthy donors.

Epstein-Barr virus nuclear antigen-1 (EBNA-1) is a protein expressed consistently in EBV infected cells and in EBV related malignant tissues. Antibodies against EBNA-1 may therefore possibly be used as a marker for disease screening. Western blot analysis of serum antibodies was performed using GST (glutathione-S-transferase) fusion proteins containing different regions of EBNA-1 as antigens. Serum samples were collected from 38 patients with nasopharyngeal carcinoma (NPC) and 38 healthy individuals in Taiwan. All samples were found IgG positive for EBNA-1 when a truncated protein GST/E1 (70-102, 325-641) was used as the antigen. Thirty-three out of 38 NPC sera (86.8%) were positive for IgA antibody against EBNA-1. The positive rate was higher in comparison with IgA antibody against VCA (65.7%) or antibody against DNase (60.5%). Only 2.6% of sera from normal individuals were positive for an IgA response against EBNA-1. The major antigenic determinants for NPC serum IgA response were between amino acid(aa) 390 to aa 459 when different portions of EBNA-1 were used as antigens. The results suggest that IgA response against EBNA-1 could be used in combination with other EBV serology markers for NPC screening.

Animals↗

PubMed1995

Evolution of coronary artery pattern according to short-axis aortopulmonary rotation: a new categorization for complete transposition of the great arteries.

OBJECTIVES: We studied the correlation between coronary artery pattern and aortopulmonary rotation in complete transposition of the great arteries. BACKGROUND: Classifications of the coronary arteries in complete transposition are puzzling and incomplete. METHODS: Coronary artery anatomy and relation of the great arteries were identified at angiography, echocardiography, surgical intervention or autopsy in 76 patients with complete transposition from 1988 to 1993. Five main types (type 0 and Shaher types 1,2,4 and 9) and their similar variants of epicardial configuration were categorized into five patterns (O, I, II, IV and IX). In addition, data from 568 cases from published reports were collected for analysis. RESULTS: As the aorta rotated from a left anterior to a directly anterior location relative to the pulmonary trunk, the left anterior descending coronary artery arose from the left-hand sinus together with the right coronary artery (type 0, one case decreased to no cases); then it gradually shifted to the left to have the same origin as the left circumflex coronary artery from the right-hand sinus (type 1, 10 cases increased to 146, p < 0.0003). When the aorta rotated farther clockwise from directly anterior to right anterior (type 1, 146 cases increased to 235; type 2, 9 cases increased to 50, p < 0.0006) or from right anterior to right lateral (type 1, 235 cases decreased to 6 cases; type 2, 50 cases decreased to 20, p < 0.00000), the left circumflex coronary artery tended to move retropulmonically and originated from the left-hand sinus with the right coronary artery (type 2). When the aorta moved from right anterior to right lateral (type 2, 50 cases decreased to 20; type 4, 13 cases increased to 14, p < 0.031) or from right lateral to right posterior (type 2, 20 cases decreased to 1; type 4, 14 cases increased to 16, p < 0.0003), the right coronary artery shifted to the right-hand sinus anteaortically to join the left anterior descending coronary artery (type 4). Finally, the left anterior descending coronary artery combined with the left circumflex coronary artery (type 9, 12 cases increased to 21, p = 0.407) to become the usual pattern for normally related great arteries. Eta-square analysis showed that the evolution from pattern O to IX was dependent on clockwise aortopulmonary rotation. CONCLUSIONS: The coronary arteries in complete transposition of the great arteries can be classified into five patterns and their evolution deduced on the basis of aortopulmonary rotation. Dependence of coronary artery type on aortopulmonary rotation made it possible to anticipate the coronary pattern from the relation of the great arteries in transposition.

Adolescent↗

PubMed1994

Delineation of a 16 amino acid sequence that forms a core DNA recognition motif in the Epstein-Barr virus EBNA-1 protein.

EBNA-1 is the sole virally specified protein required for replication of the Epstein-Barr virus latency origin and also modulates its own expression. Both of these functions are mediated through specific DNA binding. We created a series of amino acid substitutions across the previously identified DNA-binding domain of EBNA-1 to further define the amino acids required for DNA recognition. The results of electrophoretic mobility shift assays using in vitro-translated EBNA-1 (aa 408-641) polypeptides indicated that: (i) The predicted alpha helical segment between aa 477 and 487 is not directly involved in DNA recognition but appears to contribute to a critical local polypeptide conformation. (ii) The positively charged residues Arg459, Lys460, and Lys461 are dispensable for DNA binding. (iii) The region between Gly462 and Lys477 contains residues important for DNA recognition. This region is extremely sensitive to mutation. The behavior of a synthetic peptide representing EBNA-1 aa 458-478 supported the mutagenesis data. A dimer form of this peptide, which lacks the predicted alpha helical domain, was capable of binding DNA, but only nonspecifically. The effect of binding affinity on transactivation was examined in cotransfection assays. EBNA-1 mutants with reduced binding affinity also demonstrated reduced levels of transactivation.

Amino Acid Sequence↗

PubMed1994

Angiographic classification of ventricular septal defects in tetralogy of Fallot.

The ventricular septal defect (VSD) in Fallot's tetralogy (TF) was classified into four types: perimembranous (PM), muscular outlet (MO), doubly committed subarterial (DS), and DS with perimembranous extension. From July 1990 to June 1992, we used angiocardiography to define preoperatively the types of VSD in 30 cases of TF, and correlated them with the operative findings. The angiographic images used to identify the types of VSDs were anteroposterior (AP) plus cranial tilting 20-30 degrees, right anterior oblique 30 degrees plus cranial tilting 30 degrees (elongated RAO view) and true lateral view of right ventricular (RV) angiography. DS type and MO type had a shadow of muscle bar postero-inferiorly in the AP and elongated RAO views, while perimembranous type and MO superiorly in the lateral view. DS with perimembranous extension type was devoid of both shadows. The results revealed 73% accuracy rate of prediction by angiocardiography. Most of the incorrectly predicted cases were attributed to a tiny inferior muscle bar in MO type and was mistaken as pm type VSD. We conclude that routine RV angiography before correction of tetralogy of Fallot to identify the types of VSDs is feasible. This information facilitates planning of surgical strategy.

Angiocardiography↗

PubMed1994

Subaortic blind mitral pouch in a double-inlet right ventricle.

A full-term baby girl was diagnosed at birth using echocardiography to have a single ventricle with common atrioventricular valve and subaortic ridge. On the 22nd day after birth she was admitted to hospital for intensive care after sudden onset of cyanosis. Three days later she died after repeated attacks of bradycardia. At necropsy the heart was examined by sequential segmental approach. Situs solitus with double-inlet right ventricle and ventriculoarterial discordance was revealed. The left atrial floor was separated from the ventricle by a small hole leading to a translucent blind pouch, which bulged toward the subaortic outflow tract with its hypoplastic tensor apparatus connected to the subaortic infundibulum. The aortic valve was normal. The pulmonary trunk with a competent bicuspid valve arose from the left-sided rudimentary left ventricle. The pulmonary blood flow was limited by a slit-like interventricular communication. Obstruction of the pulmonary venous return due to the natural closing of the patent foramen ovale and the mitral atresia led to her premature death.

Female↗