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Biomedical subjects

L J Lin

Publications and source records attributed to L J Lin.

At least 37 records · Page 2Linked to original sources
PubMed1998

Successful delayed thrombolytic therapy in a patient with massive pulmonary embolism.

Pulmonary embolism can be a catastrophic event leading to early death or serious hemodynamic instability. Thrombolytic therapy, in addition to heparin therapy, may improve the clinical condition and reduce the chance of recurrent pulmonary embolism in some cases. However, the acceptable "time window" for thrombolytic therapy is not well documented, though it has been used successfully as late as 14 days after pulmonary embolism. Successful delayed thrombolytic therapy beyond this "time window" in patients with massive pulmonary embolism has not been reported. We report a case of massive pulmonary embolism in which thrombolytic therapy was delayed more than 1 month after symptom onset. A 56-year-old woman was taken to National Cheng Kung University Hospital because of an episode of recurrent syncope, followed by progressive shortness of breath of 1 month's duration. Hypoxemia and hemodynamic instability were noted on admission. Echocardiography and a lung perfusion scan provided strong evidence of pulmonary embolism. Subsequent pulmonary angiography confirmed the diagnosis of multiple pulmonary emboli. The patient received a standard dose of intravenous tissue plasminogen activator 7 days after admission because of persistent symptoms and hypoxemia. Her clinical condition dramatically improved after treatment. Follow-up imaging studies showed resolution of the emboli. She was discharged in good condition. This case suggests that delayed thrombolytic therapy in patients with massive pulmonary embolism can still be beneficial in selected cases, even if given more than 2 weeks after symptom onset.

Female↗
PubMed1997

Elevation of soluble adhesion molecules is associated with the severity of myocardial damage in acute myocardial infarction.

In 20 patients with acute myocardial infarction, blood samples were taken to study the serial changes in the soluble intercellular adhesion molecule-1 (ICAM-1), vascular cellular adhesion molecule-1 (VCAM-1) and E-selectin. Results indicated that soluble ICAM-1 increased significantly and persisted throughout the study period; however, soluble E-selectin was significantly elevated only transiently and decreased rapidly thereafter, and the VCAM-1 did not increase during entire study period. There was a significant correlation between the levels of ICAM-1, E-selectin 6 hours after admission, and peak creatine kinase level; the levels of ICAM-1 and E-selectin were also positively correlated with total leukocyte count at admission.

Case-Control Studies↗
PubMed1997

Natural history of left atrial spontaneous echo contrast in nonrheumatic atrial fibrillation.

A prospective study was designed to investigate potential changes of left atrial (LA) spontaneous echo contrast with time and the effects of antithrombotic therapy on its presence in 77 patients with chronic nonrheumatic atrial fibrillation (AF), using serial transesophageal echocardiography (TEE). During a mean follow-up period of 20 +/- 15 months (range 6 to 77), a total of 197 TEE studies were performed in these patients. Baseline TEE revealed that LA spontaneous echo contrast was absent in 43 patients (group 1) and present in 34 (group 2). LA thrombus was found in 8 of group 2 but in none of the group 1 patients. During the follow-up period, only 2 of the group 1 patients were receiving antithrombotic agents; the patients in group 2 without LA thrombus were treated with either warfarin or aspirin, whereas those with LA thrombus were treated with warfarin. On the latest TEE study, LA spontaneous echo contrast was observed in 19 of the group 1 patients (44%) and was persistently found in all of the group 2 patients. During the study period, no patient was found to develop new LA thrombus formation and only 4 episodes of transient ischemic attack were recorded in 4 patients (embolic event rate = 3.1% per year). Of these, 2 were observed in group 1 and the remaining 2 were from group 2 and under aspirin therapy (event rate = 2.2% and 4.7% per year, respectively). In the subgroup of patients with LA thrombus receiving warfarin therapy, follow-up TEE revealed complete resolution of the thrombi in 6 and partial resolution in the remaining 2 in spite of the persistence of LA spontaneous echo contrast; none of these patients developed clinical thromboembolic events during the study period. Thus, future occurrence of LA spontaneous echo contrast could be observed by serial TEE at a substantial rate in patients with nonrheumatic AF who have no LA spontaneous echo contrast; follow-up TEE should be recommended for these patients to detect early the potential occurrence of LA spontaneous echo contrast if preventive antithrombotic therapy is not considered. Although warfarin therapy is associated with resolution of LA thrombus, neither warfarin nor aspirin is effective for suppressing the presence of LA spontaneous echo contrast in nonrheumatic AF.

Adult↗
PubMed1997

Prevalence and clinical significance of left atrial thrombus in nonrheumatic atrial fibrillation.

The prevalence and clinical significance of left atrial thrombus were prospectively investigated in a consecutive series of 219 patients with chronic nonrheumatic atrial fibrillation using transesophageal echocardiography. Fifteen left atrial thrombi were detected in 15 of the 219 patients (6.8%); 12 of these thrombi (80%) were confined to the left atrial appendage. Left atrial spontaneous echo contrast was visualized in 85 patients (39%). All the thrombi were found in the left atria with spontaneous echo contrast. Patients with left atrial thrombus had significantly lower left ventricular ejection fraction than those without (49 +/- 14% vs. 59 +/- 14%; P < 0.05). Multivariate analysis among clinical and transthoracic echocardiographic variables showed that left ventricular ejection fraction < 50% was the only independent predictor for the presence of left atrial thrombus. A history of thromboembolism was significantly more frequent in patients with left atrial thrombus than in those without (73% vs. 32%; P < 0.005). The presence of left atrial thrombus was more specific than spontaneous echo contrast for predicting history of thromboembolism (97% vs. 80%), but its sensitivity was significantly lower (14% vs. 73%). We conclude that: (1) Transesophageal echo-detected left atrial thrombus is not uncommon in patients with chronic nonrheumatic atrial fibrillation and is exclusively observed in those with left atrial spontaneous echo contrast. (2) Impaired left ventricular systolic function may predispose the left atrial thrombus formation. (3) Left atrial thrombus is a highly specific but insensitive predictor for thromboembolic events.

Adult↗
PubMed1997

Proteolytic activities of mouse sarcoma 180 cells that are inhibited by Bowman-Birk and Kunitz protease inhibitors.

In this study, using zymogram analysis two proteolytic activities were identified in the mouse sarcoma 180 (S-180) cells that were activated by trypsin treatment and inhibited by both BBI and ACTI. These enzymes, with molecular weights of 46 kDa (dominant band) and 62 kDa (minor band), were mainly localized in the cytosol, and had optimal activity at pH 7 and 8 respectively. Their inhibition by DFP, BBI and ACTI but not EDTA and TPCK indicated they were trypsin-like serine proteases and may be the intracellular target-enzymes of protease inhibitors. The level of the precursor of the 62 kDa protease was significantly increased in the S-180 solid and soft tumors, whereas the level of the 46 kDa precursor was almost undetectable, implying that a physiological role may be played by these serine proteases during tumor invasion.

Animals↗
PubMed1996

Afebrile spontaneous pneumopyopericardium.

A 77-year-old woman had spontaneous pneumopyopericardium caused by Klebsiella pneumoniae. Chest X-ray revealed a horizontal air-fluid level in the cardiac shadow. Echocardiogram showed characteristic spontaneous contrast echoes in the pericardial effusion. She received pericardiectomy and remained in good condition postoperatively.

Aged↗
PubMed1996

Silicone cream occlusive dressing--a novel noninvasive regimen in the treatment of keloid.

BACKGROUND: The use of silicone oil in the treatment of hypertrophic scars has recently been much discussed. Silicone gel and silicone cream containing 20% silicone oil have been demonstrated to effectively treat hypertrophic scars. However, the results in treating keloid are variable. OBJECTIVE: The purpose of this study was to evaluate the clinical efficacy of silicone cream with occlusive dressing in the treatment of keloid. METHODS: An open study was performed in 15 Chinese patients with single or multiple keloids. Nineteen keloids were randomly selected and treated with silicone cream occlusive dressing (SCOD). The effectiveness was assessed using a scoring system involving elevation, redness, hardness, itching and tenderness or pain of the lesions. RESULTS: Fifteen out of 19 keloids (79%) showed significant improvement after using SCOD for 6 months. None of the keloids progressed. CONCLUSIONS: We conclude that SCOD is easy to apply, noninvasive, painless, almost free of side effects. It is especially useful in children and those who cannot tolerate the pain or inconvenience of other treatment procedures. The action mechanism of SCOD is still unclear, though hydration and occlusion rather than silicone itself may play an important role.

Adult↗
PubMed1996

Dose-response relationship between ischemic heart disease mortality and long-term arsenic exposure.

The cardiovascular effects of inorganic arsenic have been documented, but the dose-response relationship between ischemic heart disease (ISHD) and long-term arsenic exposure remains to be elucidated. Mortality rates from ISHD among residents in 60 villages of the area in Taiwan with endemic arseniasis from 1973 through 1986 were analyzed to examine their association with arsenic concentration in drinking water. Based on 1 355 915 person-years and 217 ISHD deaths, the cumulative ISHD mortalities from birth to age 79 years were 3.4%, 3.5%, 4.7%, and 6.6%, respectively, for residents who lived in villages in which the median arsenic concentrations in drinking water were <0.1, 0.1 to 0.34, 0.35 to 0.59, and > or = 0.6 mg/L. A cohort of 263 patients affected with blackfoot disease (BFD), a unique arsenic-related peripheral vascular disease, and 2293 non-BFD residents in the endemic area of arseniasis were recruited and followed up for an average period of 5.0 years. There was a monotonous biological gradient relationship between cumulative arsenic exposure through drinking artesian well water and ISHD mortality. The relative risks were 2.5, 4.0 and 6.5, respectively, for those who had a cumulative arsenic exposure of 0.1 to 9.9, 10.0 to 19.9, and > or = 20.0 mg/L-years compared with those without the arsenic exposure after adjustment for age, sex, cigarette smoking, body mass index, serum cholesterol and triglyceride levels, and disease status for hypertension and diabetes through proportional-hazards regression analysis. BFD patients were found to have a significantly higher ISHD mortality that non-BFD residents, showing a multivariate-adjusted relative risk of 2.5 (95% CI, 1.1 to 5.4).

Adolescent↗
PubMed1994

Acute myocardial infarction in young and very old Chinese adults: clinical characteristics and therapeutic implications.

To characterize acute myocardial infarction (AMI) in young adults and octogenarians, 475 AMI patients, in age subsets, were examined. The clinical features, risk factors and in-hospital mortality were compared among 17 young patients (< 40 years), 426 patients of common age (40-79 years), and 32 very elderly patients (> or = 80 years). The octogenarian patients were mainly female (male/female ratio, 0.9 vs. 4.7 in other subgroups, P < 0.005), and had more frequent atypical presentation and postinfarctional congestive heart failure; whereas infarct size, location and development of Q-wave, major arrhythmias and cardiac wall rupture were not different among these age subsets. The most common risk factors in the young group were dyslipidemia (67%) and cigarette smoking (65%), and in the octogenarian group were dyslipidemia (52%) and hypertension (50%). Among age subsets, however, the prevalence of risk factors was not significantly different except for a relatively lower smoking rate in the octogenarians. Compared with 40- to 79-year-old patients who had predominantly multi-vessel diseases, the young patients had milder coronary atherosclerosis and were more likely to have normal coronaries (27% vs. 5%, P < 0.01). Significantly more octogenarians than young patients succumbed to AMI in the hospital (44% vs. 18%, P < 0.005), usually because of a cardiogenic complication (93%). Also, the octogenarians were less likely than the younger patients to have received thrombolytic therapy, mostly because of delayed diagnosis and arrival at the hospital, or because of old age itself.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Different effects of strenuous exercise and moderate exercise on platelet function in men.

BACKGROUND: Platelets play an important role in the pathogenesis of cardiovascular diseases. It is also noticed that on one hand, regular exercise can reduce the risk of cardiovascular diseases, and on the other hand, vigorous exercise provokes sudden cardiac death. We therefore hypothesize that various intensities of exercise may affect platelet function differently. METHODS AND RESULTS: Strenuous and moderate exercise (about 50% to 55% of peak oxygen consumption, VO2peak) on a bicycle ergometer in 10 sedentary and 10 physically active healthy young men was executed on two separate occasions. Blood samples were collected before and immediately after exercise. A newly designed tapered parallel plate chamber was used to assess platelet adhesiveness. Platelet aggregation induced by ADP was evaluated by the percentage of reduction in single platelet count. beta-Thromboglobulin (beta-TG) and platelet factor 4 (PF4) were measured by ELISA. In addition, a similar study on 5 patients with stable angina were also conducted. Our results showed that (1) in the sedentary healthy group, platelet adhesiveness and aggregation were increased by strenuous exercise and depressed by moderate exercise; (2) in the active healthy group, platelet adhesiveness and aggregation were enhanced by severe exercise, whereas only aggregation was decreased by moderate exercise; (3) in the patients with stable angina, platelet adhesiveness and aggregation were enhanced by strenuous exercise and adhesiveness was suppressed by moderate exercise; (4) the degree of hemoconcentration induced by acute exercise tended to be related to the severity of exercise in all subjects; and (5) although severe exercise elevated beta-TG and PF4, there were no significant changes in beta-TG, PF4, and the ratio of beta-TG to PF4 in healthy subjects after exercise. CONCLUSIONS: It is concluded that platelet adhesiveness and aggregability may be sensitized by strenuous exercise in both healthy subjects and patients with stable angina. In contrast, platelet function can be suppressed significantly by moderate exercise in the healthy and tends to be depressed in patients with stable angina. The former may increase the risk of cardiac arrest and the latter may protect us from cardiovascular diseases. In addition, the effects of acute exercise tend to be more pronounced in the sedentary than in the active.

Adult↗
PubMed1993

Down-regulation of beta-adrenergic receptors on mononuclear leukocytes induced by dobutamine treatment in patients with congestive heart failure.

(+/-)-Dobutamine is a positive inotropic drug usually used to improve ventricular function in patients with congestive heart failure (CHF). However, it has been found that haemodynamic responses to dobutamine become blunted during continuous treatment. In this study we determined the time-dependent changes of beta-adrenergic receptors in CHF patients treated with dobutamine. Seven CHF patients received a continuous intravenous infusion of dobutamine (5 micrograms.kg-1 x min-1) for 96 h. Blood samples were obtained before and every 24 h after starting the therapy. The density of beta-adrenergic receptors on mononuclear leukocytes and the plasma concentrations of norepinephrine and epinephrine were determined. During dobutamine treatment the receptor density (fmol.mg-1, mean +/- SEM) gradually decreased from 42.8 +/- 4.4 (baseline) to 31.4 +/- 3.3 (P < 0.05), 25.2 +/- 4.0 (P < 0.01), 18.8 +/- 5.5 (P < 0.01) and 13.4 +/- 3.4 (P < 0.01) at 24, 48, 72 and 96 h, respectively. However, the plasma concentrations of norepinephrine and epinephrine were not significantly changed during the 96 h period of treatment. Thus, the beta-adrenergic receptors down-regulated as early as 24 h after the dobutamine treatment was begun in CHF patients. This receptor down-regulation was not associated with changes of plasma catecholamine concentrations, but was related rather to the development of drug tolerance to dobutamine.

Adult↗
PubMed1992

Clinical implications of left atrial spontaneous echo contrast in nonrheumatic atrial fibrillation.

The prevalence and clinical significance of left atrial (LA) spontaneous echo contrast were investigated in 103 consecutive patients with chronic nonrheumatic atrial fibrillation (AF) using transesophageal echocardiography. LA spontaneous echo contrast was visualized in 25 of 103 patients (24.3%). Age, sex, LA diameter, left ventricular diastolic and systolic dimensions, left ventricular ejection fraction, and the percentage of lone AF were not significantly different between patients with and without LA spontaneous echo contrast; however, those with LA spontaneous echo contrast were less likely to have moderate or severe mitral regurgitation. LA thrombi were observed in 7 patients (6.8%), and all 7 thrombi were found in the atria with spontaneous echo contrast. History of cerebral ischemia or peripheral embolism, or both, was significantly more frequent in patients with than without LA spontaneous echo contrast (84 vs 18%; p less than 0.001). The presence of LA spontaneous echo contrast was highly specific (94%) and predictive for thromboembolic events (positive and negative predictive values of 84 and 82%, respectively). Thus, transesophageal echo-detected LA spontaneous echo contrast is frequently found in patients with chronic nonrheumatic AF. This phenomenon may represent a precursor of thrombus formation, and its presence is associated with an increased thromboembolic risk.

Adult↗
PubMed1992

Determination of nucleic acid backbone conformation by 1H NMR.

In DNA or RNA duplexes, the six-bond C3'-O3'-P-O5'-C5'-C4'-C3' backbone linkage connecting adjacent residues contains six torsion angles (epsilon, zeta, alpha, beta, gamma, delta) but only four protons. This seriously limits the ability to define the backbone conformation by NMR using purely 1H-1H distance geometry (DG) methods. The problem is further compounded by the inability to assign two of the four backbone protons, namely the poorly resolved H5' and H5'' protons, and invariably leads to DG structures with poorly defined backbone conformations. We have developed and tested a reliable method to constrain the beta, gamma, and epsilon (and indirectly alpha and zeta) backbone torsion angles by lower-bound NOE distances to unassigned H5'/H5'' resonances combined with either 1H line widths or the conservative use of sigma J measurements; the method relies only on 1H 2-D NMR data, does not involve any structural assumptions, and leads to much improved backbone convergence among DG structures. The C4'-C5' torsion angle gamma is constrained by lower-bound NOE distances from H2' and from H6/H8 to any H5'/H5'', as well as by sigma JH4, coupling measurements in the 3.9-4.4 ppm region; delta is constrained by H1'-H4' NOE distances and by H3'-H4' and H3'-H2'' J couplings in COSY data; epsilon is partially constrained by H3' line width and/or further constrained by subtracting the minimum possible sigma JH3'-H from the observed sigma JH3' (COSY) to arrive at the maximum possible JH3'-P, which is then converted to H3'-P distance bounds. The angle beta is partially constrained via H5'-P and H5''-P distance bounds consistent with the maximum H5'-P and H5''-P J couplings derived from the observed H5' and H5'' line widths, while alpha and zeta are indirectly constrained by lower distance bounds on the observed (n)H1' to (n + 1)H5'/H5'' NOEs combined with the prior partial constraints on beta, gamma, delta, and epsilon. The combined effects of these additional constraints in determining distance geometry structures have been demonstrated using a 12-base duplex, [d(GCCGTTAACGGC)]2. Coordinate RMSDs per atom between structures refined with these constraints from random-embedded DG structures, from ideal A-DNA, and from B-DNA starting structures were less than 0.4 A for the central 8 base pairs indicating good convergence. All backbone angles for the central 8 base pairs are very well constrained with less than 10 degrees variation in any of the 48 torsion angles.

Base Sequence↗