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Biomedical subjects

J K Wang

Publications and source records attributed to J K Wang.

At least 19 recordsLinked to original sources

CNS voltage-dependent Na(+) channel expression and distribution in an undifferentiated and differentiated CNS cell line.

Upon serum removal, CAD-R1 cells undergo neurite outgrowth and an increase in voltage-dependent Na(+) current (VDNaC) density without changing their activation and inactivation properties. Insulin and endothelial cell growth supplement inhibited the increase in VDNaC density but not the neurite outgrowth. RI, RII, RIII Na(+) channel proteins were expressed in CAD-R1 cells. These proteins exhibited both similar and different distribution and clustering patterns which suggested the channel's structural differences play a role in channel distribution.

Cell Culture Techniques↗

Radiofrequency catheter ablation of tachycardia in children with and without congenital heart disease: indications and limitations.

From 1993 to 1998, a total of 100 consecutive pediatric patients with tachycardia (45 male and 55 female, aged 1 year 10 months to 17 years, 11+/-4 year) who underwent electrophysiological study were reviewed. Eleven of them were younger than 5 years. Two had tachycardia-related cerebrovascular accident. Congenital heart disease was found in 12 patients. After propofol anesthesia, the clinical tachycardia could not be induced in three (two atrial tachycardia and one AV nodal re-entrant tachycardia) and became nonsustained in five (atrial tachycardia). Mechanical ablation occurred in three and two had subsequent recurrences. Among the 85 cases who received radiofrequency ablation, the overall final success rate of RF ablation for all diagnoses was 94% with a diagnosis-specific success rate ranging from 100 to 57%. Tachycardia cardiomyopathy was noted in four (three atrial tachycardia and one junctional ectopic tachycardia) and all regressed after successful ablation. Success in two patients with left posterioseptal accessory pathway could only be achieved by delivering the energy at the middle cardiac vein. Two patients with right atrial isomerism had an 'AV nodal-to-AV nodal tachycardia' which was eliminated by ablation. Total recurrence rate was 13% but final success was achieved in all during re-study except the three patients who refused re-intervention. The atrial tachycardia developed in postoperative congenital heart disease was associated with the lowest success rate (57%) and highest recurrence rate (25%). Procedure-related complications occurred in four; two with transient brachial palsy, one with first-degree AV block and one with blood loss requiring blood transfusion. In conclusion, the experience of this single center confirmed the efficacy and safety of radiofrequency catheter ablation in treating pediatric arrhythmias, but the limitations in postoperative arrhythmias and the effects of propofol on tachycardia induction (especially the atrial tachycardia) need to be improved.

Anesthetics, Intravenous↗

The Nef protein of HIV-1 associates with rafts and primes T cells for activation.

The Nef protein is an important virulence factor of primate lentiviruses, yet the mechanisms by which it exerts this influence are imperfectly understood. Here, using an inducible system, we demonstrate that Nef increases IL-2 secretion from T cells stimulated via CD3 or CD28. This effect requires the conservation of the Nef myristoylation signal and SH3-binding proline-based motif. Together with several proteins involved in the initiation and propagation of T cell signaling, Nef associates with membrane microdomains known as rafts. The Nef-mediated superinduction of IL-2 reflects the activation of both NFAT and NFkappaB. Accordingly, Nef also enhances HIV-1 transcription in response to CD3 or CD28 stimulation. Nef-induced IL-2 hyperresponsiveness is also observed in primary CD4 lymphocytes. Overall, these data suggest that Nef acts at the level of rafts to prime T cells for activation. Likely consequences of this effect are the promotion of HIV-1 replication and the facilitation of virus spread.

Antigens, CD↗

Right lung agenesis with left pulmonary artery sling.

We report on a 2-month-old infant girl who had right pulmonary agenesis and an unusual course of the left pulmonary artery. Computed tomography and cardiac catheterization showed that the left pulmonary artery arose from the main pulmonary artery, crossing the midline, and reaching the left lung via an aberrant course between the esophagus and trachea. The coexistence of right pulmonary agenesis and left pulmonary sling is extremely rare. Unlike in other reports, our patient remained symptom-free and in good health, with normal growth and development until age 2 years, when she died from complications during an attack of bronchiolitis caused by respiratory syncytial virus.

Bronchiolitis↗

Protection of T cells from activation-induced cell death by Fas+ B cells.

Naive CD4+ T cells proliferate strongly in response to stimulation by superantigens such as staphylococcal enterotoxin B (SEB). However, when these same cells revert to a resting phenotype and are subjected to restimulation with either SEB or anti-CD3, the majority of these SEB-responsive cells undergo Fas ligand (FasL)-mediated activation-induced cell death (AICD). We investigated the impact of Fas expression on T cell AICD by utilizing B cell stimulators that lacked functional FasL and either expressed or did not express the Fas receptor. Our results indicate that B cells play an important role in modulating the level of T cell AICD via the Fas/FasL pathway. Activated B cells expressing high levels of Fas receptor can redirect the FasL expressed by T cells primed to undergo AICD away from the T cells and prevent the induction of AICD in these cells. Furthermore, B cells stimulated through both the CD40 receptor and membrane IgM appear to mediate a stronger protective effect on T cells by virtue of their resistance to FasL-mediated cytolysis. These observations suggest a mechanism by which normal B cell and T cell responses to foreign antigen are maintained, while responses to self antigen are not.

Animals↗

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↗

[Major-polygene effect analysis of resistance to bacterial blight (Xanthomonas campestris pv. oryzae) in rice].

Five crosses between resistance and susceptible were analyzed to study major-polygene effect using major-polygene mixed mode. The result showed that 3 of 5 crosses were controlled by both major gene and polygene. In addition, there were large variation of additive effect, variance as well as heredity of major gene polygene in 3 crosses. Major gene was predominant in resistant variation, but durability should be considered. We suggested that construct major-polygene system be constructed in the long run in breeding program to ensure a durable and high level of resistance to constrain fluctuation of races of Xanthomonas campestris pv. oryzae population.

Oryza↗

Outcomes of transcatheter valvotomy in patients with pulmonary atresia and intact ventricular septum.

The results of transcatheter valvotomy in pulmonary atresia with intact ventricular septum (PA-IVS) patients are presented with an attempt to identify the predictive factors for pulmonary valvotomy alone as definitive treatment. Between June 1995 and December 1997, 14 PA-IVS neonates with tripartite right ventricle underwent an attempted pulmonary valvotomy. For perforation of the pulmonary valve, a guidewire was used in 4, and a radiofrequency guidewire in 10 patients. Two outcome groups were identified. Group I included those in whom transcatheter treatment achieved a definitive success; group II patients required surgery despite an initial successful valvotomy. The attempt failed in 3 patients, 1 of whom had pericardial effusion. Perforation of the pulmonary valve was achieved in 11 patients: 2 with a guidewire and 9 with a radiofrequency guidewire. A subsequent balloon valvuloplasty was performed in these 11 patients. After valvuloplasty, mean right ventricular pressure decreased from 124 +/- 24 to 60 +/- 15 mm Hg (p <0.01). One died of heart failure and infection 10 days later, despite successful weaning from prostaglandin E1. Group I patients (n = 6) were treated with transcatheter valvotomy alone. Group II patients (n = 4) required right ventricular outflow patch. Significant differences between the 2 groups (group I vs II) were identified in tricuspid valve Z value (0.52 +/- 0.37 vs -1.25 +/- 0.48, p <0.05), pulmonary valve Z value (-3.47 +/- 0.59 vs -5.43 +/- 0.94, p <0.05), and ratio of right-to-left ventricular area on the apical 4-chamber view (0.73 +/- 0.06 vs 0.49 +/- 0.03, p <0.05). There were no significant differences in hemodynamic characteristics between the 2 groups. After a follow-up period ranging from 7 to 35 months (mean 18 +/- 10.3), the most recent echocardiograms in the 10 patients showed a mean pressure gradient across the pulmonary valve of 17 +/- 15 mm Hg. All 10 patients had an oxygen saturation of >92%. Transcatheter valvotomy using a radiofrequency guidewire is a safe and effective treatment in selected patients with PA-IVS. Transcatheter valvotomy can be a definitive treatment in PA-IVS patients with a tricuspid valve Z value > or = -0.1, pulmonary valve Z value > or = -4.1 and ratio of right-to-left ventricular area > or = 0.65.

Catheterization↗

Cu2+ induces Ca2+-dependent neurotransmitter release from brain catecholaminergic nerve terminals.

CuCl2, ZnCl2 and NiCl2, but not CdCl2 or CoCl2, induced transmitter release from superfused rat hippocampal and striatal synaptosomes preloaded with, respectively, [3H]noradrenaline and [3H]dopamine. Cu2+ was the most potent and effective, acting in a concentration- (0.1-300 microM) and time-dependent (peak effect occurring at 2-3 min) manner. The amount of Cu2+-induced release over a 5 min period is similar to that induced by depolarization with high KCl or the K+ channel blocker 4-aminopyridine. However, the time course of the Cu2+-induced release is slower and the effect of Cu2+ is not reversed by washout. Cu2+-induced catecholamine release requires extracellular calcium (Ca2+) and is inhibited by the Ca2+ channel blocker Cd2+, and in the case of noradrenaline, by the voltage-gated Na+ channel blocker tetrodotoxin. The ability of Cu2+ to induce massive Ca2+-dependent transmitter release from brain catecholaminergic nerve terminals may contribute to the neuropathological processes associated with Cu2+ toxicity in Wilson's disease.

4-Aminopyridine↗

Balloon dilatation for critical pulmonary stenosis.

This study was conducted to investigate the outcome of balloon valvuloplasty for critical pulmonary stenosis in young infants. During a 6.2-year period between January 1992 and February 1998, 34 infants with critical pulmonary stenosis, aged 1 to 58 days (16.8+/-16.6 days), underwent attempted balloon valvuloplasty in this institution. The procedure was accomplished in 28 patients, but failed in six. Surgical pulmonary valvotomy was performed in the six patients with one mortality. Immediately following valvuloplasty, the mean right ventricular systolic pressure decreased from 109.2+/-28.6 to 55.1+/-23.6 mm Hg in the 28 patients (P<0.01). The mean pressure gradient decreased from 85.6+/-29.4 to 26+/-21.4 mm Hg (P<0.01). However, one who had a severely hypoplastic right ventricle requiring prolonged prostaglandin E1 infusion after valvuloplasty underwent a right ventricular outflow tract patch. After a follow-up period ranging from 2 months to 6.4 years (30.5+/-19.1 months), one patient developed recurrent pulmonary stenosis and underwent a repeated balloon valvuloplasty. Of the 27 patients (79%) with a definitive success of balloon valvuloplasty, the mean pressure gradient estimated with Doppler echocardiography at most recent follow-up was 15.2+/-6.8 mm Hg. Therefore, balloon valvuloplasty is the procedure-of-choice for critical pulmonary stenosis. Surgery should be reserved for those with unsuccessful balloon valvuloplasty.

Arrhythmias, Cardiac↗

Transarterial occlusion of patent ductus arteriosus with Gianturco coils in pediatric patients: a preliminary result in central Taiwan.

OBJECTIVE: We wish to present the preliminary result of transarterial occlusion of patent ductus arteriosus (PDA) with Gianturco coils in pediatric patients in central Taiwan. MATERIALS AND METHODS: We attempted occlusion of PDA with Gianturco coils in a total of 26 consecutive patients, 13 infants and 13 children, 23 female and three male, between July 1 1997 to September 30 1998. Median patient age was 2.57 years (from 0.25 to 14.02 years old). Median patient weight was 10.8 kg (4.0 to 36.0 kg). Premature babies with PDA, full-term babies who were less than three months old and patients who had other congenital heart disease were not included in this study. All PDAs were approached transarterially from the femoral artery. Coils were selected to provide a helical diameter that was twice or more the minimum ductus diameter and a length approximating five loops. In five patients who had a PDA diameter > or =3.5 mm, we used a snare technique to assist coil delivery beforehand, and to test coil stability, or to retrieve coil that had migrated to the pulmonary artery afterwards. Physical auscultation, chest radiographs and echocardiography with color Doppler were done in all patients within 24 h, and one, two, three, six and 12 months after coil occlusion. RESULTS: The median ductus minimum diameter was 2.3 mm (range, 1.0 to 4.7 mm). Fifteen patients had the megaphone type (type A), four had the window type (type B), five had the tubular type (type C), one had the aneurysmal type (type D) and one had the elongated conical type (type E). Twenty-one patients underwent single coil occlusion and five had multiple coils occlusion. Twenty-one patients had immediate angiographic closure of the ductus and disappearance of heart murmur at 15 min after the procedure. Dark-brown urine (hemoglobinuria) was found in one patient, 10 h after the first procedure, due to a mild residual ductal shunt. Two more coils were implanted in a second procedure that was performed within 24 h, and the ductus was completely occluded. The dark-brown urine regressed. At one month follow-up, four patients had mild residual ductal shunts, which were completely occluded by one more coil in three patients and by two more coils in the other patient. Malpositioned coils were deployed in five patients immediately after the procedure. In total, the closure rate at 15 min, within 24 h, and at one, two, three, six and 12 months were 81, 85, 85, 100, 100, 100 and 100%, respectively. In one year of follow-up, there was no instance of coil migration, ductus reopening or stenosis of the left pulmonary artery. CONCLUSIONS: Transarterial occlusion of PDA, with a Gianturco coil having approximately five loops, can be effectively achieved in patients with a minimum ductus diameter up to 4.7 mm. In patients with a ductus of more than 3.5 mm, the snare-assisted technique was employed advantageously to control coil delivery with accuracy and stability. Coil malposition or migration can be easily retrieved using a 10-mm Nitnol snare catheter. Hemoglobinuria, due to intravascular hemolysis, may regress within 24 h after the second attempt at coil implantation.

Adolescent↗

Nef-induced CD4 and major histocompatibility complex class I (MHC-I) down-regulation are governed by distinct determinants: N-terminal alpha helix and proline repeat of Nef selectively regulate MHC-I trafficking.

The Nef protein of primate lentiviruses triggers the accelerated endocytosis of CD4 and of class I major histocompatibility complex (MHC-I), thereby down-modulating the cell surface expression of these receptors. Nef acts as a connector between the CD4 cytoplasmic tail and intracellular sorting pathways both in the Golgi and at the plasma membrane, triggering the de novo formation of CD4-specific clathrin-coated pits (CCP). The downstream partners of Nef in this event are the adapter protein complex (AP) of CCP and possibly a subunit of the vacuolar ATPase. Whether Nef-induced MHC-I down-regulation stems from a similar mechanism is unknown. By comparing human immunodeficiency virus type 1 (HIV-1) Nef mutants for their ability to affect either CD4 or MHC-I expression, both in transient-transfection assays and in the context of HIV-1 infection, it was determined that Nef-induced CD4 and MHC-I down-regulation constitute genetically and functionally separate properties. Mutations affecting only CD4 regulation mapped to residues previously shown to mediate the binding of Nef to this receptor, such as W57 and L58, as well as to an AP-recruiting dileucine motif and to an acidic dipeptide in the C-terminal region of the protein. In contrast, mutation of residues in an alpha-helical region in the proximal portion of Nef and amino acid substitutions in a proline-based SH3 domain-binding motif selectively affected MHC-I down-modulation. Although both the N-terminal alpha-helix and the proline-rich region of Nef have been implicated in recruiting Src family protein kinases, the inhibitor herbimycin A did not block MHC-I down-regulation, suggesting that the latter process is not mediated through an activation of this family of tyrosine kinases.

CD4 Antigens↗

A variant of long QT syndrome manifested as fetal tachycardia and associated with ventricular septal defect.

Two patients with a novel variant of long QT syndrome are described. The clinical course was characterised by an in utero onset of ventricular tachycardia and atrioventricular block (at 26 and 30 weeks' gestational age, respectively), and an association with a ventricular septal defect. Studies of both patients' families identified relatives with prolonged QT interval, syncope, or sudden death. One patient died of intractable ventricular tachycardia at 4 days old. The other received beta blocker treatment and a pacemaker. She died suddenly at the age of 10 months. The unique association with ventricular septal defect and the malignant clinical course warrants further molecular diagnosis of this novel variant of long QT syndrome.

Female↗

p38 but not p44/42 mitogen-activated protein kinase is required for nitric oxide synthase induction mediated by lipopolysaccharide in RAW 264.7 macrophages.

Protein kinase C (PKC)-alpha, -betaI, and -delta are known to be involved in the lipopolysaccharide (LPS)-induced nitric oxide (NO) production in RAW 264.7 macrophages. The role of mitogen-activated protein kinases (MAPK) p44/42 and p38 in the LPS effect was studied further. LPS-mediated NO release and the inducible form of NO synthase expression were inhibited by the p38 inhibitor, SB 203580, but not by the MAPK kinase inhibitor, PD 98059. Ten-minute treatment of cells with LPS resulted in the activation of p44/42 MAPK, p38, and c-Jun NH2-terminal kinase. Marked or slight activation, respectively, of p44/42 MAPK or p38 was also seen after 10-min treatment with 12-O-tetradecanoylphorbol-13-acetate, but c-Jun NH2-terminal kinase activation did not occur. Tyrosine kinase inhibitor, genestein, attenuated the LPS-induced activation of both p44/42 MAPK and p38, whereas the PKC inhibitors, Ro 31-8220 and calphostin C, or long-term treatment with 12-O-tetradecanoylphorbol-13-acetate resulted in inhibition of p44/42 MAPK activation, but had only a slight effect on p38 activation, indicating that LPS-mediated PKC activation resulted in the activation of p44/42 MAPK. Nuclear factor-kappaB (NF-kappaB)-specific DNA-protein-binding activity in the nuclear extracts was enhanced by 10-min, 1-h, or 24-h treatment with LPS. Analysis of the proteins involved in NF-kappaB binding showed translocation of p65 from the cytosol to the nucleus after 10-min treatment with LPS. The onset of NF-kappaB activation correlated with the cytosolic degradation of both inhibitory proteins of NF-kappaB, IkappaB-alpha and IkappaB-beta. IkappaB-alpha was resynthesized rapidly after loss (1-h LPS treatment), whereas IkappaB-beta levels were not restored until after 24-h treatment. SB 203580 but not PD 98059 inhibited the LPS-induced stimulation of NF-kappaB DNA-protein binding. Thus, activation of p38 but not p44/42 MAPK by LPS resulted in the stimulation of NF-kappaB-specific DNA-protein binding and the subsequent expression of inducible form of NO synthase and NO release in RAW 264.7 macrophages.

Animals↗

Tricuspid atresia with persistent truncus arteriosus.

The association of tricuspid atresia and persistent truncus arteriosus is a very rare congenital anomaly. We report a newborn with a prenatal diagnosis of tricuspid atresia, in whom associated type II persistent truncus arteriosus was found by postnatal echocardiography. The patient had mild cyanosis and developed heart failure soon after birth. Balloon septostomy was performed to enlarge the interatrial communication. However, her condition rapidly deteriorated and she died of sepsis and heart failure at the age of 14 days.

Female↗

Differential pulmonary flow in hypoplastic left heart syndrome.

We report a case of hypoplastic left heart syndrome associated with restrictive interatrial communication and partial anomalous pulmonary venous connection via a right lower pulmonary vein draining to the inferior vena cava. We found unequal pulmonary artery pressure and different pulmonary artery structure, with the right pulmonary artery being lower in pressure and more tortuous and dilated in its peripheral branches than the left. This was attributed to the variant degrees of pulmonary venous obstruction. The left pulmonary venous return was severely obstructed by the restrictive interatrial communication, whereas the anomalous right lower pulmonary vein drained into the inferior vena cava, with less obstruction. To the best of our knowledge, there has never before been a report of differential pulmonary flow associated with a partial anomalous pulmonary vein, in a case of hypoplastic left heart syndrome.

Echocardiography, Doppler, Color↗

Pulmonary vein atresia with Shone's anomaly in an infant: a case report.

We report a case of individual pulmonary vein atresia associated with multiple levels of left heart obstruction, including aortic coarctation, valvular aortic stenosis, and parachute mitral valves with stenosis. The diagnosis of pulmonary vein obstruction is likely to be missed in patients who also have other left heart obstructive diseases, since the latter usually dominates the clinical presentation. We diagnosed the existence of individual pulmonary vein atresia preoperatively via cardiac catheterization. The pulmonary artery angiograms revealed back and forth motion of the dye with no visualization of either a capillary or venous phase on the lesion side. The pulmonary capillary wedge pressure was unevenly elevated and highest on the lesion side. The results were later confirmed by operation and autopsy. Thus, selective pulmonary artery catheterization and angiography remains a good diagnostic tool to rule out the existence of pulmonary vein obstruction in cases which have multiple levels of left heart obstruction.

Aortic Coarctation↗