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Biomedical subjects

J L Lin

Publications and source records attributed to J L Lin.

At least 109 records · Page 6Linked to original sources
PubMed1995

Transesophageal echocardiographic assessment of mitral valve position and pulmonary venous flow during cardiopulmonary resuscitation in humans.

BACKGROUND: The mechanisms of blood flow during closed-chest cardiopulmonary resuscitation (CPR) in humans have been debated since the technique was first described in 1960. Two competing models, the cardiac pump theory and the thoracic pump theory, have been proposed, and some investigators have used mitral valve position during the downstroke of chest compression to distinguish between them. Previous studies using either transthoracic or transesophageal echocardiography have yielded conflicting results, and there have been few, if any, hemodynamic or echocardiographic studies on pulmonary venous flow (PVF) during CPR. METHODS AND RESULTS: In this study, transesophageal two-dimensional and pulsed Doppler echocardiography were used to study mitral valve position and flow, together with PVF, in 20 adult patients undergoing manual CPR. In the 17 patients who could be analyzed, the mitral valve closed in 5 patients (group 1) during chest compression but stayed open or opened further in the remaining 12 patients (group 2). Peak forward mitral flow occurred during the release phase in group 1 but during the compression phase in group 2. During chest compression, PVF occurred in the forward direction (from the pulmonary vein to the left atrium) in 8 of the group 2 patients (group 2a) and in the backward direction (from the left atrium to the pulmonary vein) in all group 1 patients and the remaining 4 patients in group 2 (group 2b). The downtime (time from collapse to CPR) was significantly shorter (P < .05) for those in group 1 (7.0 +/- 4.4 minutes) than in groups 2a (19.8 +/- 7.7 minutes) and 2b (17.8 +/- 6.8 minutes). CONCLUSIONS: Transesophageal echocardiography performed during manual CPR in humans disclosed three different patterns of mitral valve position and PVF during chest compression. The presence of an opened mitral valve with forward mitral flow and backward pulmonary venous flow during chest compression in a small number of subjects underscores this heterogeneity in blood flow and suggests the possible existence of a "left atrium pump" in addition to the currently known "left ventricle pump" and "chest pump" mechanisms.

Adult↗
PubMed1995

Critical, acutely poisoned patients treated with continuous arteriovenous hemoperfusion in the emergency department.

STUDY OBJECTIVE: To investigate the efficiency of a new non-pump hemoperfusion technique, continuous arteriovenous hemoperfusion, in the treatment of critical, acutely poisoned patients. SETTING: Emergency department of a general hospital. PARTICIPANTS: Acutely poisoned patients who failed to respond to intensive supportive treatment and needed hemoperfusion therapy. INTERVENTIONS: All patients received continuous arteriovenous hemoperfusion therapy for 4 to 8 hours. Toxicant clearances were determined by obtaining serial theophylline and phenobarbital levels every 2 hours before, during, and after continuous arteriovenous hemoperfusion. Platelet counts, whole-blood activated clotting time, and vital signs were monitored. RESULTS: The clinical condition of these patients improved rapidly after continuous arteriovenous hemoperfusion was started. The treatments were performed easily, and no significant complications occurred. The clearances of theophylline and phenobarbital were 192.79 +/- 1.55 mL/min and 290.25 +/- 25.33 mL/min, respectively, similar to those of conventional hemoperfusion. CONCLUSION: Continuous arteriovenous hemoperfusion is a simple, safe, effective, and less costly alternative to conventional hemoperfusion, especially in the EDs of hospitals without hemoperfusion facilities immediately available.

Acute Disease↗
PubMed1995

Forced expression of chimeric human fibroblast tropomyosin mutants affects cytokinesis.

Human fibroblasts generate at least eight tropomyosin (TM) isoforms (hTM1, hTM2, hTM3, hTM4, hTM5, hTM5a, hTM5b, and hTMsm alpha) from four distinct genes, and we have previously demonstrated that bacterially produced chimera hTM5/3 exhibits an unusually high affinity for actin filaments and a loss of the salt dependence typical for TM-actin binding (Novy, R.E., J. R. Sellers, L.-F. Liu, and J.J.-C. Lin, 1993. Cell Motil. & Cytoskeleton. 26: 248-261). To examine the functional consequences of expressing this mutant TM isoform in vivo, we have transfected CHO cells with the full-length cDNA for hTM5/3 and compared them to cells transfected with hTM3 and hTM5. Immunofluorescence microscopy reveals that stably transfected CHO cells incorporate force-expressed hTM3 and hTM5 into stress fibers with no significant effect on general cell morphology, microfilament organization or cytokinesis. In stable lines expressing hTM5/3, however, cell division is slow and sometimes incomplete. The doubling time and the incidence of multinucleate cells in the stable hTM5/3 lines roughly parallel expression levels. A closely related chimeric isoform hTM5/2, which differs only in the internal, alternatively spliced exon also produces defects in cytokinesis, suggesting that normal TM function may involve coordination between the amino and carboxy terminal regions. This coordination may be prevented in the chimeric mutants. As bacterially produced hTM5/3 and hTM5/2 can displace hTM3 and hTM5 from actin filaments in vitro, it is likely that CHO-expressed hTM5/3 and hTM5/2 can displace endogenous TMs to act dominantly in vivo. These results support a role for nonmuscle TM isoforms in the fine tuning of microfilament organization during cytokinesis. Additionally, we find that overexpression of TM does not stabilize endogenous microfilaments, rather, the hTM-expressing cells are actually more sensitive to cytochalasin B. This suggests that regulation of microfilament integrity in vivo requires stabilizing factors other than, or in addition to, TM.

Actin Cytoskeleton↗
PubMed1995

The evolution of platelet aggregability in patients undergoing catheter ablation for supraventricular tachycardia with radiofrequency energy: the role of antiplatelet therapy.

Forty-two consecutive patients were checked for profiles of platelet aggregability before, during, and 10 and 30 minutes after catheter ablation. They were randomized into Group A (n = 20) who accepted intravenous aspirin (in 0.015 g/kg body weight) and Group P (n = 22) who accepted only placebo treatment. Blood samples were drawn from ascending aorta (Ao) and main pulmonary artery (MPA) simultaneously at each time period. In Group P, the EC50 of substrate induced platelet aggregability decreases significantly during (for ADP, from 1.72 to 0.78 mumol/L for samples from Ao, P < 0.0001; and from 1.68 to 0.69 mumol/L for MPA, P < 0.0001; for collagen, from 2.26 to 1.34 micrograms/mL for Ao, P < 0.005, and from 2.40 to 1.64 micrograms/mL, P < 0.0001) and 10 minutes after successful ablation (for ADP, to 0.70 mumol/L for Ao, P < 0.000, and to 0.61 mumol/L for MPA, P < 0.0001; for collagen, to 1.54 micrograms/mL for Ao, P < 0.01, and to 1.63 micrograms/mL, P < 0.0001), and then returned to baseline levels 30 minutes later (all P = NS) compared with comparative baseline levels. The levels of thromboxane B2 (TXB2) had the similar evolution. The evolution of platelet aggregability profiles was not associated with total energy dose, duration of energy application, duration of procedure, impedance, and ablation site. However, there were moderate positive correlations between the TXB2 levels and tip temperatures (r = 0.56, P < 0.05 for Ao and r = 0.65, P < 0.01 for MPA). These results suggest that increased platelet aggregability can occur during and 10 minutes after radiofrequency current ablation and antiplatelet therapy can maintain "flat" response of platelet aggregability to radiofrequency energy, which may provide possible benefits in preventing the occurrence of the complication.

Adenosine Diphosphate↗
PubMed1995

Perinodal slow potential as a local guide for transcatheter radiofrequency ablation of atrioventricular nodal reentrant tachycardia: therapeutic efficacy and electrophysiological mechanisms of success.

BACKGROUND: A specific local indicator in the Koch's triangle could be critical to the complication-free treatment of atrioventricular nodal reentrant tachycardia by transcatheter radiofrequency ablation. Recording of perinodal slow potential reflects a slow conduction area, and probably indicates the location of the slow pathway component of the circuit. Specific ablation of the slow pathway would carry the least risk of atrioventricular block. METHOD AND RESULTS: Guided by the mapped perinodal slow potential, atrioventricular nodal reentrant tachycardia was successfully eliminated in all of 55 consecutive patients in one session. Fifty two patients (94.5%) had confirmed slow potential at the final success sites. Despite the good result, the underlying electrophysiological mechanisms of early success from slow-potential-guiding catheter ablation were heterogeneous: selective slow pathway eradication in 31 patients (56.4%, group A), selective slow pathway modification in 18 patients (32.7%, group B), inadvertent fast pathway damage in six patients (10.9%, group C). Group B patients had the preservation of dual atrioventricular nodal pathways, adequate atrio-Hisian delay, fast pathway facilitation, and a higher frequency of inducible, single non-conducted nodal echo (15/18, 83.3% v 6/31, 19.4% in group A, P << 0.001). The upper communicating path of the circuit was implicated as another site of radiofrequency destruction. Three recurrences were documented in follow up study. However, reablation by the same approach caused complete atrioventricular block in one patient (1.7%, 1/58 procedures). None of the local characteristics of ablation sites was an independent predictor of procedure outcome. CONCLUSIONS: Perinodal slow potential is not a specific slow pathway indicator in transcatheter radiofrequency ablation of atrioventricular nodal reentrant tachycardia. Multiple strategic sites of the reentry circuit may be damaged through similar local signals.

Adolescent↗
PubMed1995

Electrophysiological properties of dual atrioventricular nodes in patients with right atrial isomerism.

There are reports that in right atrial isomerism the conduction system has paired sinus nodes and paired atrioventricular nodes. Electrophysiological studies were performed in two patients with right atrial isomerism. One patient had a delta wave on the surface electrocardiogram without tachycardia attacks. The other, who did not have manifest pre-excitation, had recurrent narrow QRS tachycardia. Electrophysiological studies suggested the presence of dual atrioventricular nodes. Only unidirectional atrioventricular or ventriculoatrial conduction was demonstrated for these dual atrioventricular nodes even after infusion of isoprenaline. It is suggested that unidirectional conduction may be a common property of the dual atrioventricular nodes in right atrial isomerism and that the absence of retrograde ventriculoatrial conduction protects the patients against tachycardia.

Atrioventricular Node↗
PubMed1995

Relationship of body iron status and serum aluminum in chronic renal insufficiency patients not taking any aluminum-containing drugs.

The present study examines the serum aluminum (Al) and daily urine Al excretion in 50 patients with chronic renal insufficiency (CRI) who are not taking any Al-containing agents. The influence of body iron stores and hematological indexes on the above parameters were also studied. Data on a group of 20 healthy subjects not taking any drugs were included for comparisons. The basal Al levels in CRI patients (10.5 +/- 9.7 micrograms/l) were significantly higher than those (3.8 +/- 2.4 micrograms/l) of the normal subjects. In addition, the renal Al clearance (2.98 +/- 0.35 ml/min) in CRI patients was significantly lower than that (4.93 +/- 0.21 ml/min) in normal subjects. Although all serum Al levels of our patients were within the nontoxic range (< 50 micrograms/l), the results of our study showed a negative correlation between serum Al and serum transferrin saturation (r = -0.40, p < 0.005) as well as serum iron (r = -0.406, p < 0.005). There was a negative correlation between daily urine Al excretion and serum ferritin levels (r = -0.305, p = 0.031). The study group is further divided into 2 subgroups, i.e. group A (ferritin < 100 micrograms/l) and group B (ferritin > 300 micrograms/l). The daily urine Al excretion in group A was higher than that in group B. In conclusion, our study first demonstrates that Al tends to be accumulated in patients with CRI, similar to Al in patients with hemodialysis, and the chronic low-level Al exposure in CRI patients may affect body iron status and metabolism, or iron status may play a role in Al absorption and excretion.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

Value of local electrogram characteristics predicting successful catheter ablation of left-versus right-sided accessory atrioventricular pathways by radiofrequency current.

Despite similar guidance by local electrogram criteria, catheter ablation of right-sided accessory atrioventricular (AV) pathways by radiofrequency current has been less effective than that of left-sided ones. In order to elucidate the possible diversities in local electrosignal criteria, we systematically analyzed the morphological and timing characteristics of 215 bipolar local electrograms from catheter ablation sites of 65 left-sided accessory AV pathways and of 356 from those of 37 right-sided ones in 92 consecutive patients with Wolff-Parkinson-White syndrome or AV reentrant tachycardia incorporating concealed accessory AV pathways. After stepwise multivariate analysis, we selected the presence of a possible accessory pathway potential, local ventricular activation preceding QRS complex for 20 ms or more during ventricular insertion mapping, and the local retrograde ventriculoatrial (VA) continuity, local retrograde VA interval < or = 50 ms, electrogram stability (left-sided targets only), retrograde accessory pathway potential (right-sided targets only) during atrial insertion mapping, as independent local electrogram predictors for successful ablation of left- and right-sided accessory AV pathways. Combination of all local electrogram predictors could have moderate chance of success (80 and 51%) for the ventricular and atrial insertion ablation of left-sided accessory AV pathways, but only low probability of success (40% in ventricular insertion ablation) or very low sensitivity (12.5% in atrial insertion ablation) for right-sided ones. In conclusion, with the present approach, successful catheter ablation of right-sided accessory AV pathways, compared to left-sided ones, still necessitate a breakthrough in the precision mapping and the efficiency of energy delivery.

Adolescent↗
PubMed1995

Apical segmental dysfunction in hypertrophic cardiomyopathy: progression into end-stage heart failure with sudden cardiac death.

Apical segmental dysfunction is an unusual finding in hypertrophic cardiomyopathy (HCM). It is characterized by a poor clinical course and a high incidence of malignant ventricular tachyarrhythmias. Long-term prognosis of patients with HCM and apical segmental dysfunction is still unclear. We report 2 cases of apical segmental dysfunction in HCM in whom progressive apical dilatation and congestive heart failure developed. Both patients died suddenly, and intractable ventricular tachyarrhythmias were documented in 1 case during resuscitation. This report provides further evidence that apical segmental dysfunction might predict a subgroup of patients with HCM who are likely to develop end-stage heart failure and are at high risk of sudden cardiac death.

Adolescent↗
PubMed1995

Left atrial spontaneous echo contrast in patients with rheumatic mitral valve disease in sinus rhythm. Implication of an altered left atrial appendage function in its formation.

Thirty-nine patients who had rheumatic mitral valve disease in sinus rhythm were studied to compare echocardiographic and hemodynamic characteristics between those with and without left atrial (LA) spontaneous echo contrast. Patients were divided into two groups according to the presence (group 1, n = 17) or absence (group 2, n = 22) of the echo contrast. Transthoracic echocardiography and transesophageal echocardiography were performed in all patients within 1 week of cardiac catheterization study. Group 1 patients (5 men and 12 women; mean age, 47.7 +/- 13.1 years) showed smaller mitral valve area, greater transmitral valve pressure gradient, and absence of moderate to severe mitral regurgitation compared with group 2 patients (7 men and 15 women; mean age, 47.8 +/- 14.3 years). There was no significant difference in LA dimension, left ventricular end-systolic and end-diastolic dimensions, or in left ventricular ejection fraction between the two groups of patients. Left atrial appendage function was studied with Doppler in 26 patients. Patients (n = 10) with LA spontaneous echo contrast had significantly lower LA appendage ejection fraction (20.34 +/- 10.76% vs 34.16 +/- 13.13%; p < 0.05) and lower LA appendage peak emptying velocity (0.17 +/- 0.09 m/s vs 0.27 +/- 0.12 m/s; p < 0.05) than those (n = 16) without echo contrast. It is concluded that obstruction to mitral flow and altered LA appendage contractile function, not the LA size, are likely to be more important factors for the development of LA and LA appendage spontaneous echo contrast in patients with rheumatic mitral valve disease (predominant mitral stenosis) who are in sinus rhythm. These findings further substantiate that blood stasis in the LA cavity and the LA appendage is the mechanism fundamental to the formation of such spontaneous echo contrast.

Adult↗
PubMed1995

Increased body cadmium burden in Chinese women without smoking and occupational exposure.

To investigate the chronic low-level environmental cadmium and zinc exposure of Chinese women and find the relationships between these parameters and hypertension, 58 women without histories of smoking and occupational exposure were conducted into this cross-section study and divided into three groups: Group I: 24 normal healthy, Group II: 24 untreated essential hypertension, and Group III: 10 untreated nonessential hypertension women. The serum cadmium and daily urinary cadmium excretion of Group II (1.69 +/- 0.92 micrograms/L; 2.43 +/- 1.93 micrograms/d) were significantly higher than those of Group I (0.88 +/- 0.92 micrograms/L; 1.07 +/- 1.45 micrograms/d) as well as Group III (0.92 +/- 0.91 micrograms/L; 0.19 +/- 0.23 micrograms/d). The ratio of urinary zinc (micrograms)/urinary creatinine (g) of Group II (865.99 +/- 460.54 micrograms/g) was higher than that of Group I (622.39 +/- 250.96 micrograms/g). The ratio of urinary cadmium concentrations (micrograms)/urinary creatinine (g) of all healthy Chinese women was 1.30 +/- 1.67 which is higher than that of other nations in the world except Japanese. After adjusting age and body mass index, we found mean arterial pressure positively correlated with serum cadmium in all subjects (p = 0.0058). The mean arterial pressure also positively correlated with serum cadmium (p = 0.0017) as well as daily urinary cadmium excretion (p = 0.0088) in all women except the nonessential group. Both the ratios of urinary zinc (micrograms)/urinary creatinine (g) (p = 0.0165) and urinary cadmium (micrograms)/urinary creatinine (g) positively (p = 0.0246) related to mean arterial pressure in women of Group I and II.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

Electrocardiographic findings of organophosphate intoxication in emergency department as predictors of prognosis: a retrospective analysis.

To investigate the clinical significance of electrocardiographic (ECG) findings in patients with organophosphate intoxication and to find predictors for prognosis, we reviewed 170 patients whose ECG was taken in the emergency department (ED) from 1981 to 1989. There were 67 cases whose ECG showed prolongation of corrected Q-T interval (QTc). In this group, the mortality rate, respiratory failure rate and frequency of ventricular premature contraction (VPC) were significantly higher than those of patients without QTc prolongation. In the group with presence of VPC, the overall mortality rate and respiratory failure rate were also significantly higher when compared with those without VPC. We concluded that QTc prolongation and the presence of VPCs in patients with organophosphate intoxication may predict their clinical respiratory failure and mortality.

Adolescent↗
PubMed1995

Effects of isovanihuperzine A on cholinesterase and scopolamine-induced memory impairment.

AIM: To study the effects of isovanihuperzine A (IVHA) on cholinesterase and scopolamine-induced memory deficit. METHODS: AChE and BuChE activities were determined by the colorimetric method of Ellman. The Ki value was determined by the plotting method of Lineweaver and Burk. In a behavioral test, rats were trained to perform a radial arm maze task using a partially baited procedure. RESULTS: The anti-AChE activity of IVHA was comparable to huperzine A (Hup-A), and was more potent than those of physostigmine and galanthamine with an IC50 value of 0.11 mumol.L-1. IVHA was a mixed competitive type with a Ki value of 32 nmol.L-1. It bound to AChE in a reversible manner. IVHA at a dose of 0.2 mg.kg-1 ip significantly reversed scopolamine-induced working memory and reference memory impairments in radial arm maze. CONCLUSION: IVHA is a new potential reversible AChE inhibitor and merits further study as a cognitive enhancer.

Acetylcholinesterase↗
PubMed1994

Thermal inactivation of shrimp deoxyribonuclease with and without sodium dodecyl sulfate.

Due to the differences in sample treatment, purified shrimp DNase migrates to different positions in sodium dodecyl sulfate (NaDod-SO4) polyacrylamide gel electrophoresis. DNase molecules migrating to some of these positions are enzymatically active as revealed by the DNase activity stain in situ. When the sample is not heated, DNase molecules (Form I) migrate to a position corresponding to an apparent Mr of 22 000 and are stain DNase-active. When the sample is heated with NaDod-SO4, DNase molecules (Form II) migrate to the apparent Mr of 39 000 position and are also DNase-active. In contrast, when the sample is heated without NaDod-SO4, DNase molecules (Form II') migrate to the same position as Form II but are DNase-inactive. When the sample is heated in the presence of beta-mercaptoethanol (with or without NaDod-SO4), the inactive Form III is generated. Form III must be the fully extended polypeptide because its apparent Mr is very close to the true Mr of DNase. These treated samples were also analyzed for DNase activity by diluting DNase-NaDod-SO4 into the DNase (hyperchromicity) assay solution. The results are consistent in that only Forms I and II are DNase-active. However, Form I differs from Form II in the time required for expression of DNase activity. After dilution of NaDod-SO4. Form II requires approx. 60 min to attain full activity while Form I is active immediately. Form II itself is inactive. The activity found at the Mr 39 000 position is due to conversion of Form II to the active Form I, as revealed by two-dimensional NaDod-SO4 gel electrophoresis. The sample heated without NaDod-SO4 soon contains active Form II, indicating that Form II is an intermediate during the production of Form II'. When Form II' is heated with NaDod-SO4, it does not refold back to the native state through Form II, suggesting that Form II' is irreversibly denatured. Thus, the anomalous behaviors of shrimp DNase in NaDod-SO4 gel electrophoresis have been utilized to study, in the presence and absence of NaDod-SO4, the thermal unfolding, as well as the refolding to the active enzyme during cooling and NaDod-SO4 removal.

Animals↗
PubMed1994

Fracture of a perfusion balloon catheter during coronary angioplasty.

In a 74-year-old patient with increasing angina, an attempt was made to dilate an ostial stenosis in the first diagonal artery. The initial attempt with a long balloon catheter was unsuccessful. Because of chest pain associated with hypotension during balloon inflations, a second attempt with a perfusion balloon catheter resulted in fracture of this catheter's tip (14 mm long) in the artery. Bypass graft surgery was performed and the retained fragment was easily removed by arteriotomy. The patient made an uneventful recovery.

Aged↗