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Biomedical subjects

D C Wang

Publications and source records attributed to D C Wang.

At least 55 records · Page 3Linked to original sources
PubMed1996

Abrogation of the Fc gamma receptor IIA-mediated phagocytic signal by stem-loop Syk antisense oligonucleotides.

The role of Syk kinase in Fc gamma receptor (Fc gamma R) IIA-mediated phagocytosis was examined with two forms of antisense oligodeoxynucleotides (ODNs) designed to hybridize to human Syk mRNA. Monocytes were incubated with linear and stem-loop antisense ODNs targeted to Syk mRNA. When complexed with cationic liposomes, stem-loop Syk antisense ODN with phosphorothioate modification exhibited stability in fetal bovine and human serum. The stem-loop Syk antisense ODN at a concentration of 0.2 microM inhibited Fc gamma RIIA-mediated phagocytosis by 90% and completely eliminated Syk mRNA and protein in monocytes, whereas scrambled-control ODNs had no effect. The Syk antisense ODNs did not change beta-actin mRNA levels and Fc gamma RII cell-surface expression. In addition, stem-loop Syk antisense ODN inhibited Fc gamma RI and Fc gamma RIIIA-mediated phagocytosis. These data indicate the efficacy of stem-loop Syk antisense ODN for targeting and degrading Syk mRNA and protein and the importance of Syk kinase in Fc gamma receptor-mediated phagocytosis. Immunoblotting assay demonstrated that Fc gamma RII tyrosine phosphorylation after Fc gamma RII cross-linking did not change in the absence of Syk protein. These results indicate that Syk kinase is required for Fc gamma RIIA-mediated phagocytic signaling and that Fc gamma RII cross-linking leads to tyrosine phosphorylation of Fc gamma RII independent of Syk kinase.

Animals↗
PubMed1995

[The prevalence of Toxoplasma infection among pregnant women and their newborn infants in Chengdu].

Purpose of the study was to determine the prevalence of toxoplasma infection among the pregnant women and their newborn infants in Chengdu and to identify risk factors of acquiring toxoplasma infection. The Maternal and Child Health Hospital was selected by random cluster sampling method in the study. Each pregnant women admitted to the above hospital consecutively and her surviving newborn at birth were included in this survey. History, physical examination and blood specimens were obtained from 1,211 pairs of mother-newborns. ELISA was used to detect toxoplasma IgG and IgM antibodies. Results revealed that sera prevalence of toxoplasma IgG antibodies and IgM antibodies of pregnant women were 39.14% and 4.21% respectively. Seraprevalence of toxoplasma IgM antibodies of newborn infants was 1.07%. Congenital malformation of newborn infants may be associated with congenital toxoplasma infection (P < 0.05, OR = 6.32).

Animals↗
PubMed1994

[Experimental study on the pharmacologic effects of zeng sheng pin pian].

Zeng Sheng Pin Pian (ZSPP) is a mixture of medicinal herbs which has been shown to be effective in the secondary prevention of esophageal cancer in a high-risk area among a population with severe esophageal dysplasia. This study in mice aimed at elucidating the possible mechanism of the cancer-preventing activity of ZSPP. The results indicate that ZSPP is a good biologic response modifier (BRM) as shown by its enhancing effects on lymphocyte blastogenesis, IL-2 secretion, NK cell activity, delayed-type hypersensitivity reaction to DNCB, hemolysin response to SRBC and the phagocytic function of the reticulo-endothelial system. While ZSPP did not inhibit the growth of S-180 in mice, it exhibited significant inhibitory effect on ornithine decarboxylase (ODC) activity induced by the application of croton oil to the skin. Taken together, the immune enhancing activity and the anti-tumor-promoting activity of ZSPP could explain, at least in part, its efficacy in the prevention of esophageal cancer among high-risk people with precursor dysplastic lesions.

Animals↗
PubMed1993

Configurational entropy is the driving force of ethanol action on membrane architecture.

A colligative thermodynamic framework is developed to describe the action of ethanol on membranes. The partitioning of ethanol into a membrane structure imparts a randomness, configurational entropy, that stabilizes that structure from an energetic standpoint. When partitioning between membrane structures differs, the equilibrium between them is altered to favor the structure with the largest partition coefficient for ethanol. The action of ethanol and temperature originate in entropy and are equated through entropy. Membrane equilibria that are predicted to be most sensitive to the action of ethanol (where dilute concentrations of ethanol cause a perturbation equal to a large change in temperature) are those that exhibit a small thermal entropy change and a large difference in solute partitioning between membrane structures. Our model predicts that ethanol does not act on a single membrane structure, but on both structures in an equilibrium. The thermodynamic framework is applied to the action of ethanol on cooperative equilibria in a dipalmitoyl lecithin model membrane. Ethanol-induced perturbations are monitored by electron paramagnetic resonance (EPR) using the spin label, Tempo. The equilibrium between the gel and ripple-structures (L beta'-->P beta', pretransition) exhibits a small change in thermal entropy and, as predicted, is more sensitive to the action of ethanol than the equilibrium between the ripple and fluid bilayer-structures (P beta'-->L alpha, main transition) which exhibits a large thermal entropy change. The framework suggests that ethanol acts through entropy, as does temperature, thereby upsetting the natural thermal balance that maintains membrane architecture.

Chemical Phenomena↗
PubMed1993

Recurrent conduction in accessory pathway and possible new arrhythmias after radiofrequency catheter ablation.

Radiofrequency catheter ablation was performed in 142 patients with 166 accessory pathways. One hundred thirty-six patients with 160 accessory pathways underwent successful ablation in the first ablation session. Serial follow-up electrophysiologic studies were performed immediately (30 minutes), early (5 to 7 days), and late (3 to 6 months) after successful ablation to determine the recurrent accessory pathway conduction and possible new arrhythmias. After a minimum follow-up period of 6 months (mean, 14 +/- 3 months), accessory pathway conduction recurred in 13 patients (9.6%), with recurrent tachycardia in three patients (2.2%). Five of the recurrent accessory pathways had decremental conduction properties. Incidence of recurrent accessory pathway conduction was similar in different accessory pathway locations (6.4% to 9.0%). Patients with concealed accessory pathways (12.2 vs 2.9%; p < 0.05), and patients without accessory pathway potentials in the ablation site (15.5% vs 2.2%; p < 0.05) had a higher recurrence rate. Patients without tachycardia in the late electrophysiologic study did not have recurrent tachycardia during follow-up. New arrhythmias, including atrial and ventricular arrhythmias, which were detected by 24-hour Holter monitoring, were apparent only on the first day after ablation. The findings indicate that the overall incidence of recurrent accessory pathway conduction was low and that possible new arrhythmias were rare in the late follow-up period.

Adult↗
PubMed1993

Arrhythmogenicity of catheter ablation in supraventricular tachycardia.

To evaluate arrhythmogenicity in patients who receive a modified direct-current (DC) shock ablation (distal pair of electrodes connected in common as the cathode) or radiofrequency (RF) ablation of supraventricular tachycardia, a prospective study was performed with signal-averaged ECG, 24-hour Holter monitoring, electrophysiologic study (EPS) for ventricular tachycardia (VT), and treadmill exercise test. Sixty-nine consecutive patients with documented paroxysmal supraventricular tachycardia were included. Twenty-eight patients proved to have atrioventricular nodal reentrant tachycardia, and 41 patients had atrioventricular reciprocating tachycardia that involved accessory atrioventricular pathways. The first 34 patients received DC shock ablation and the other 35 patients received RF ablation. Signal-averaged ECG, Holter monitoring, and EPS for VT were performed before ablation, immediately after ablation, then 1 week, 2 weeks (Holter monitoring), 1 month (except EPS), and 3 months after ablation. Treadmill exercise testing was performed before ablation, and at 1 week and 3 months after ablation. The root mean square, low-amplitude signal and QRS duration of signal-averaged ECG disclosed no significant change after either DC or RF ablation up to 3 months. Late potential developed in only one patient in the DC shock group and it was considered to be innocuous because neither VT nor ventricular fibrillation was noted or induced. Increases in the number of ventricular premature contractions and in short-run VT were detected by Holter monitoring in the first week after either mode of ablation (p < 0.001 for the DC shock group; p < 0.05 for the RF group), which were greater (p < 0.05) and lasted longer in the DC shock group than in the RF group.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1993

Selective radiofrequency catheter ablation of fast and slow pathways in 100 patients with atrioventricular nodal reentrant tachycardia.

One hundred patients received selective radiofrequency ablation of retrograde fast pathway (32 patients, group I) or slow pathway (68 patients, group II) to treat drug-refractory atrioventricular nodal reentrant tachycardia. In group I, a mean of 6 +/- 3 radiofrequency pulses eliminated the retrograde fast pathway. Thirty patients were free of symptoms and were not receiving antiarrhythmic drugs; two patients had accidental atrioventricular block. One patient had recurrent tachycardia and received a repeated ablation (slow pathway ablation). In group II, a mean of 9 +/- 4 radiofrequency pulses eliminated the slow pathway in 68 patients. All patients were free of symptoms and were not receiving antiarrhythmic drugs. One patient had recurrent tachycardia and received a repeated ablation. Serial follow-up electrophysiologic studies (immediate [20 to 30 minutes], early [5 to 7 days], and late [3 to 6 months]) showed that selective ablation of retrograde fast pathway was associated with nonspecific injury on the antegrade fast pathway (increase of AH interval) without effects on the slow pathway. Selective ablation of slow pathway was associated with nonspecific injury on the retrograde fast pathway in 15 patients (22%), but the antegrade fast pathway conduction parameters did not change significantly. Thus retrograde and antegrade fast pathway may be anatomically similar or have different sensitivities to radiofrequency energy, and slow pathway may be anatomically distinct from fast pathway. We conclude that (1) selective radiofrequency ablation of retrograde fast or slow pathway could cure atrioventricular nodal reentrant tachycardia with a high success rate (98%) and a low recurrence rate (2%) during a follow-up period of 6 to 18 months, but fast pathway ablation was associated with accidental atrioventricular block (5%), and (2) serial follow-up electrophysiologic studies elucidated the possible mechanisms of cure in atrioventricular nodal reentrant tachycardia.

Adolescent↗
PubMed1993

Radiofrequency ablation of left-sided accessory atrioventricular pathways in patients with unusual coronary sinus.

Four patients with left-sided accessory pathways (APs) and unusual coronary sinus (CS) received radiofrequency ablation. Unusual CS included occlusion of CS (patient 1), acute angulation of proximal CS (patients 2 and 3), and narrowing of CS orifice and proximal segment (patient 4). CS catheterization and AP mapping along the CS could not be performed in the four patients. Radiofrequency ablation by left ventricular retrograde technique for the manifest left posteroseptal AP (patient 1), concealed left posterior AP (patient 2), and transseptal left atrial technique for the manifest left posteroseptal AP (patient 3) and manifest left posterior AP (patient 4) were performed successfully without CS catheter guidance. This study suggests that radiofrequency ablation of left-sided AP with unusual CS is feasible by some special techniques.

Adult↗
PubMed1993

Studies on long-acting insulin: crystal structure of Arg-B31 human insulin at 2.0A resolution.

The crystal structure of Arg-B31 human insulin (ABHI), a long-acting insulin derivative, has been determined at 2.0 A resolution by using X-ray diffraction analysis. The final crystallographic R factor of the structure model after the refinement is 0.189 with the bond length r. m. s deviation of 0.018 A. The refined structure of ABHI showed that the conformation of B-chain C-terminal residues was more stable than that in the native molecule. A striking structural feature of ABHI was an additional ion pair formed between Arg-B31 of molecule I and Glu-B21 of molecule II in a dimer, and three ionic bonds between the neighbouring molecules thereby appeared on the surface of ABHI hexamer. These secondary bonds generated by the insertion of the residue Arg-B31 should make the rate of dissociation of ABHI hexamer slow down when it was injected into the body and the property of protraction should be produced by a 'depot effect'. This ought to be the main structure basis of the prolonged action of ABHI. The results observed here demonstrate that the main idea we used in search for long-acting insulin is reasonable and correct which goes like this: making some additional non-covalent bonds between insulin monomers so as to slow down the dissociation of insulin oligomers and gain the protraction from a 'depot effect', which may be used as a principle in the further research. It also shows an impressive example that the experimental result reported here is in agreement with the theoretical prediction before the structural determination.

Crystallization↗
PubMed1992

Comparison of direct-current and radiofrequency ablation of free wall accessory atrioventricular pathways in the Wolff-Parkinson-White syndrome.

To evaluate and compare the safety and efficacy of catheter-mediated direct-current (DC) or radiofrequency (RF) ablation in patients with free wall accessory atrioventricular pathways, 95 patients with free wall accessory atrioventricular pathway-mediated tachyarrhythmias underwent catheter ablation. Immediately after ablation, 27 of 30 accessory pathways (90%) were ablated successfully with DC, but 2 of the 27 had early return of conduction and received a second ablation session; 3 of 8 (38%) and 57 of 62 (92%) accessory pathways were ablated successfully with RF through a small-tip (2 mm) and a large-tip (4 mm) electrode catheter, respectively. Complications in DC ablation included transient hypotension (2 patients) and pulmonary air-trapping (2 patients) and in RF ablation, cardiac tamponade (1 patient) and suspicious aortic dissection (1 patient); myocardial injury and proarrhythmic effects were more severe in DC ablation. Procedure and radiation exposure time were significantly longer in RF ablation (DC, 3.6 +/- 0.2 hours, 34 +/- 4 minutes; RF 4.2 +/- 0.5 hours, 50 +/- 10 minutes). This study confirms that RF ablation is associated with little morbidity and few complications, and RF ablation with a large-tip electrode catheter is an effective and relatively safe nonsurgical method for treatment of free wall accessory atrioventricular pathway-mediated tachyarrhythmias.

Adult↗
PubMed1992

Reversibility of left ventricular dysfunction after successful catheter ablation of supraventricular reentrant tachycardia.

Fourteen patients (mean age, 48 +/- 19 years) with left ventricular dysfunction in the absence of underlying organic heart disease underwent catheter ablation (nine with direct-current energy and five with radiofrequency energy) to treat drug-refractory, symptomatic supraventricular reentrant tachycardia (mean duration of tachycardia, 22 +/- 17 years). Clinical tachycardias were accessory pathway-mediated tachyarrhythmia (12 patients) and atrioventricular nodal reentrant tachycardia (two patients). Changes of ventricular function after successful ablation, as assessed by radionuclide ventriculography and echocardiography, showed a decrease in left ventricular end-systolic dimension (39 +/- 6 mm to 34 +/- 6 mm; 32 +/- 6 mm; p < 0.05) and in left ventricular end-diastolic dimension (55 +/- 5 mm to 52 +/- 3 mm; 51 +/- 3 mm; p < 0.05) in the early (2 to 3 months) and late (6 to 8 months) follow-up periods, increase of nuclear ejection fraction (38% +/- 8% to 46% +/- 7%; p < 0.05) and fractional shortening (28% +/- 7% to 36% +/- 8%; p < 0.05) in the late follow-up period. Increase of fractional shortening was mainly due to decrease in the end-systolic dimension. These findings suggest that prolonged attacks of uncontrolled supraventricular tachycardia may result in left ventricular dysfunction, which is reversible after successful catheter ablation of the arrhythmias.

Adult↗
PubMed1992

Catheter ablation of accessory atrioventricular pathways in 114 symptomatic patients with Wolff-Parkinson-White syndrome--a comparative study of direct-current and radiofrequency ablation.

To evaluate and compare the safety and efficacy of catheter-mediated direct-current and radiofrequency ablation in patients with Wolff-Parkinson-White syndrome, 114 patients with accessory pathway-mediated tachyarrhythmias underwent catheter ablation. Electrophysiologic parameters were similar in patients undergoing direct-current (group 1, 52 patients with 53 accessory pathways) and radiofrequency (group 2, 62 patients with 75 accessory pathways) ablation. Immediately after ablation, 50 of 53 accessory pathways (94%) were ablated successfully with direct current, but 2 of the 50 accessory pathways had early return of conduction and required a second ablation; 72 of 75 accessory pathways (96%) were ablated successfully with radiofrequency current. In the three accessory pathways in which radiofrequency ablation was unsuccessful, a later direct-current ablation was successful. During follow-up (group 1, 14 to 27 months; group 2, 8 to 13 months), none of the patients with successful ablation had a recurrence of tachycardia. Complications in direct-current ablation included transient hypotension (two patients), accidental atrioventricular block (one patient), and pulmonary air trapping (two patients); complications in radiofrequency ablation included cardiac tamponade (one patient) and suspicious aortic dissection (one patient). Myocardial injury and proarrhythmic effects were more severe in direct-current ablation. The length of the procedure and the radiation exposure time were significantly shorter in direct-current (3.5 +/- 0.2 hours, 30 +/- 4 minutes) than in radiofrequency (4.1 +/- 0.4 hours, 46 +/- 9 minutes) ablation. Findings in this study confirm the impression that radiofrequency ablation is associated with fewer complications than direct-current ablation and radiofrequency ablation with a large-tipped electrode catheter is an effective and relatively safe nonsurgical method for treatment of Wolff-Parkinson-White syndrome.

Atrial Fibrillation↗
PubMed1992

Radiofrequency catheter ablation for treatment of Wolff-Parkinson-White syndrome--short- and long-term follow-up.

One hundred and twenty-five patients with accessory pathways mediated tachyarrhythmias underwent radiofrequency ablation. Right-sided accessory pathways were ablated from the atrial aspect of the tricuspid anulus (all from the femoral vein approach) and the left-sided accessory pathways were ablated from the atrial or ventricular aspect of the mitral anulus. Immediately after the procedures, 3 of 8 accessory pathways (38%) and 131 of 137 accessory pathways (95%) were ablated successfully with radiofrequency through a small-tip (2 mm) and a large-tip (4 mm) electrode catheter, respectively. Seven of the 11 accessory pathways that failed radiofrequency ablation had a later successful direct current ablation. During follow-up (3 to 22 months), serial electrophysiological study showed that 11 of the 114 patients (10%) with successful ablation had return of accessory pathway conduction (2 had recurrence of tachycardia, 2%). Complications included accidental AV block (1 patient), cardiac tamponade (1 patient) and possible aortic dissection (1 patient). Transient proarrhythmic effects (more atrial and ventricular premature beats) were seen during the first week and sustained ventricular tachyarrhythmias were not inducible. In a successful session, procedure and radiation exposure times (including the time for diagnostic procedures) were 3.8 +/- 0.2 h and 45 +/- 4 min, respectively. This study confirms that radiofrequency ablation with a large-tip electrode catheter is an effective and relatively safe nonsurgical method for treatment of Wolff-Parkinson-White syndrome, with a low complication and recurrence rate.

Adult↗
PubMed1992

Catheter ablation of free wall accessory atrioventricular pathways in 89 patients with Wolff-Parkinson-White syndrome--comparison of direct current and radiofrequency ablation.

To evaluate and compare the safety and efficacy of catheter-mediated direct current (DC) or radiofrequency (RF) ablation in patients with free wall accessory atrioventricular pathways, 89 patients with free wall accessory atrioventricular pathway (AP)-mediated tachyarrhythmias underwent catheter ablation. Electrophysiological parameters were similar in the patients with DC (group I, 29 patients with 30 APs) or RF (group II, 60 patients with 64 APs) ablation. Immediately after ablation, it was seen that 27 of 30 APs (90%) had been ablated successfully with DC, but two of the 27 APs had early return of conduction and received a second ablation session; three of eight APs (38%) and 53 of 56 APs (95%) were ablated successfully with RF through a small-tip (2 mm) and a large-tip (4 mm) electrode catheter, respectively. Seven of the eight APs who had a failed RF ablation later had a successful DC ablation. During the follow-up (group I, 14 to 27; group II, 8 to 14 months), all successfully ablated patients had no recurrence of tachycardia. Complications in DC ablation included transient hypotension (two patients), and pulmonary air-trapping (two patients); in RF ablation the complications included cardiac tamponade (1 patient) and suspicious aortic dissection (1 patient); myocardial injury (reflected by peak CK-MB, 34 +/- 5 vs 15 +/- 4 IU.l-1) and pro-arrhythmic effects (new atrial and ventricular arrhythmias) were more severe in those who had DC ablation. Procedure and radiation exposure time were significantly longer in RF ablation (DC, 3.6 +/- 0.2 h, 34 +/- 4 min; RF 4.0 +/- 0.4 h, 46 +/- 10 min). This study confirms that RF ablation with a large-tip electrode catheter is an effective and relatively safe non-surgical method for treatment of free wall accessory atrioventricular pathway-mediated tachyarrhythmias.

Adult↗
PubMed1992

Safety and efficacy of a modified catheter-mediated ablation of accessory pathways.

Fifty-one consecutive patients underwent modified catheter-mediated direct-current ablation of accessory pathways. Energy was delivered through the distal pair of electrodes (dual electrode configuration) of a 6F quadripolar catheter to the internal surface of the right or left atrioventricular (AV) annulus. In an attempt to prevent the later resumption of accessory pathway conduction, one additional shock was given after the initial successful interruption of accessory pathways. A mean of 2.7 shocks with cumulative energy of 453 +/- 32 Joules/patient interrupted the accessory pathways in 47 patients and modified the accessory pathway conduction in 2 patients. Forty-eight patients were asymptomatic and free of any antiarrhythmic agents with a follow-up ranging from 3-20 months (mean 12 +/- 1 months), without early or late serious complications (AV block or tamponade). Conduction characteristics, concealed or manifest, and recording of accessory pathway activity did not affect the outcome. Mean cumulative energy and number of applications of energy to achieve a successful outcome were lower in patients with concealed (376 +/- 31 Joules, 2.4 +/- 0.2 shocks) than manifest accessory pathways (516 +/- 50 Joules, 2.9 +/- 0.2 shocks). At the successful ablation sites, the mean shortest retrograde ventriculoatrial interval during orthodromic reentrant tachycardia (VA') was 80 +/- 3 msec (78% had VA' less than 90 msec) and was not different between concealed and manifest accessory pathways; the mean shortest antegrade AV interval was 47 +/- 3 msec in manifest preexcitation; the mean ratio of atrial to ventricular wave amplitude was not significantly different between left-sided (0.8 +/- 0.1) and right-sided (1.1 +/- 0.2) accessory pathways (p greater than 0.05). A successful outcome was achieved in 94% of 51 patients. This procedure is relatively safe and effective, regardless of the location of the accessory pathway.

Adult↗
PubMed1992

Reappraisal of intermediate-term follow-up of radiofrequency ablation of accessory atrioventricular pathways for treatment of Wolff-Parkinson-White syndrome.

To evaluate the safety and efficacy of catheter mediated radiofrequency (RF) ablation in patients with Wolff-Parkinson-White syndrome, 125 patients with accessory pathway (AP) mediated tachyarrhythmias underwent RF ablation. Right-sided APs were ablated from the atrial aspect of the tricuspid annulus (all from the femoral vein approach) and the left-sided APs were ablated from the atrial or ventricular aspect of the mitral annulus. Immediately after ablation, 3 of 8 APs (38%) and 131 of 137 APs (95%) were ablated successfully with RF through a small-tip (2 mm) and a large-tip (4 mm) electrode catheter, respectively. Seven of the 11 APs where RF ablation failed had a later successful DC ablation. During follow-up (3 to 22 months), 11 of the 114 patients (10%) with successful ablation had return of accessory pathway conduction (2 had recurrence of tachycardia (2%)). Complications included transient myocardial injury (peak CK-MB 15 +/- 3 IU/l), transient proarrhythmic effects (more atrial and ventricular premature beats), accidental AV block (1 patient), cardiac tamponade (1 patient) and suspicion of aortic dissection (1 patient). In successful sessions, procedure and radiation exposure time were 3.8 +/- 0.2 h and 45 +/- 4 min, respectively. This study confirms that RF ablation with a large-tip electrode catheter is an effective and relatively safe nonsurgical method for treatment of Wolff-Parkinson-White syndrome.

Adult↗