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Biomedical subjects

H C Lue

Publications and source records attributed to H C Lue.

At least 73 records · Page 4Linked to original sources
PubMed1993

Postnatal maturation of inwardly rectifying potassium current in isolated ventricular myocytes.

We have used the whole-cell voltage-clamp method to study the inwardly rectifying potassium channel in ventricular myocytes isolated from neonatal (N, < 3 days), infant (I, 10-17 days) and mature (M, > 3 months) rabbits. Currents were elicited by serial hyper- and de-polarization from a holding potential of -80 mV in the presence and absence of barium chloride (2 mM). Barium-sensitive currents, which showed properties of inward rectification and a reverse potential at -80 to -70 mV, actually reflected currents through inwardly rectifying potassium channels. The current-voltage relations and inward rectification occurring over the range of -50 to -10 mV were relatively similar in the three groups. However, the slope conductance of Ikl decreased and the extent of inward rectification increased with maturation. The slope conductance of Ikl was 3.45 +/- 0.42 nS/pF (n = 8) for N myocytes, 2.72 +/- 0.45 nS/pF (n = 11) for I myocytes and 1.28 +/- 0.19 nS/pF (n = 8) for M myocytes (p < 0.05 among the three groups and between each group). The greater slope conductance of Ikl is important in maintaining the electrical stability in smaller immature cells with larger axial resistance. The age-related changes of Ikl may contribute to the progressive lengthening of the action potential of myocytes. In summary, the present study has identified the maturation-associated changes of Ikl which are characterized by a decrease in slope conductance and an increase in the extent of inward rectification which can in part explain the transition of action potential characteristics.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1993

Characterization of sodium inward currents and their responses to lidocaine in immature and mature rabbit ventricular myocytes.

Using the whole-cell voltage clamp method, sodium (Na) channel properties and their responses to lidocaine were studied in ventricular myocytes isolated from neonatal (N, < 3 days), infant (I, 10-17 days) and mature (M, > 3 months) rabbits. Developmental changes in the Na channels were characterized by a progressive right-shift in the inactivation curves and a faster recovery from inactivation. Lidocaine (10 microM) effectively reduced the peak Na currents in M myocytes, but had little affect on the current-voltage curve in N myocytes. The steady-state h inactivation curve shifted toward the left (ie, more negative potentials) after lidocaine, and the extent of the left-shift increased with maturation. Similarly, the magnitude of prolongation in Na channel recovery from inactivation by lidocaine increased with age. However, lidocaine at a higher concentration (30 microM) in N myocytes effectively blocked the Na channels, and the degree of suppression was comparable to that in M myocytes with 10 microM lidocaine. These data suggest that the Na channels of N myocytes per se are less sensitive to lidocaine. The results of this study indicate that the extent of Na channel inactivation becomes smaller during postnatal maturation. However, the Na channel of immature myocytes is less sensitive to the widely used Na channel blocker, lidocaine, which preferentially binds to the inactive state of the Na channel.

Age Factors↗
PubMed1993

Cardiovascular disorders in Turner's syndrome and its correlation to karyotype.

Forty-nine out of 66 patients with Turner's syndrome and different karyotypes underwent full cardiological evaluations (physical examination, electrocardiography, chest X-ray and echocardiography). Congenital cardiovascular anomalies were found in 11 patients (22.4%). Among the cardiac anomalies in patients with Turner's syndrome, aortic malformations (aortic coarctation [27%], aortic stenosis [18%] and bicuspid aortic valve [18%]) were the most frequent. We observed that the most severe malformations were found in those with karyotype 45,X or 45,X/46,XX. No anomalies were detected in patients with the X isochromosome or those mosaic with the Y component.

Adolescent↗
PubMed1992

Infantile cardiac hemangioendothelioma.

A 4-month-old infant with cardiac hemangioendothelioma presented with thrombocytopenia, and pericardial effusion, as well as signs and symptoms of heart failure. This is the first reported case of infantile cardiac hemangioma successfully treated with steroids.

Heart Atria↗
PubMed1992

Efficacy of balloon valvuloplasty in treating mild pulmonary stenosis.

Balloon pulmonary valvuloplasty (BPV) is a well accepted treatment for moderate and severe pulmonary stenosis. However, the efficacy of BPV in treating mild pulmonary stenosis is still unanswered. Therefore, the efficacy of BPV in treating patients with mild pulmonary stenosis was compared to that in treating patients with moderate or severe pulmonary stenosis. A total of 46 patients with pulmonary stenosis were arbitrarily divided into 3 groups; Group I consisted of 9 patients with a pressure gradient less than 40 mm Hg, Group II consisted of 5 patients with a pressure gradient ranged from 40 to 50 mm Hg, and Group III consisted of 32 patients with a gradient greater than 50 mm Hg. Following BPV, the gradient reduced significantly in all 3 groups (p less than 0.05 in each group). The efficacy of BPV in the 3 groups was evaluated and compared by two parameters; one is the percentage of gradient reduction, the other is the right ventricular pressure ratio (RV post-bpv/RV pre-bpv). The percentage of gradient reduction in Group I, II, and III were 28 +/- 20, 55 +/- 17 and 70 +/- 9% respectively. The right ventricular pressure remained 84 +/- 11, 59 +/- 16, and 46 +/- 12% of pre-valvuloplasty level in Group I, II and III respectively. If the efficacy of BPV was compared among the 3 groups. Groups III had the best efficacy and Group I had the worst.(ABSTRACT TRUNCATED AT 250 WORDS)

Catheterization↗
PubMed1991

Junctional ectopic tachycardia in infancy: report of two cases.

Junctional ectopic tachycardia (JET) in infancy is one of the serious arrhythmias which can be fatal. Typical features of JET include rapid and irregular heart beats with atrioventricular dissociation. Two cases of JET are reported: Case 1 was a 35-week-gestational age newborn who was found to have hydropsy and fetal tachycardia at the 21st week of gestational age. Antiarrhythmic agents including digoxin, propranolol and verapamil were administered to his mother to treat the fetal arrhythmia without success. JET was recognized at birth which was spontaneously converted into a sinus rhythm at 1 month of age. The maternal history revealed that two previous pregnancies ended in hydrops fetalis, and one of these was documented to have fetal tachycardia. Case 2 was a 6-month-old male infant with JET and congestive heart failure. After failure of various antiarrhythmic agents, amiodarone finally slowed down his heart rate and controlled his congestive heart failure.

Anti-Arrhythmia Agents↗
PubMed1990

Chronological changes in genetic variance and heritability of anthropometric characteristics among Chinese twin infants.

In order to examine the chronologic changes in genetic variance and heritability of anthropometric characteristics of Chinese infants in Taiwan, a total of 521 pairs of same-sexed twin neonates given birth in four major general teaching hospitals in Taipei City were studied. Based on the placental pattern and 12 red blood cell antigens, 428 MZ and 93 DZ twin pairs were identified and followed up to the age of one year. There was no significant genetic variance for all anthropometric characteristics adjusted for sex and gestational week before the age of six months. After adjusting for sex and gestational week, a significant genetic variance was observed at the age of six months, with heritability values of 0.51 (weight), 0.63 (head circumference), 0.77 (chest circumference), and 0.53 (arm circumference), as well as at one year, although with considerably lower heritability values. This implies that growth is dynamically determined by both genetic and environmental factors during infancy.

Age Factors↗
PubMed1990

Genetic variance and heritability of temperament among Chinese twin infants.

In order to examine the genetic variance and heritability of temperament among Chinese infants in Taiwan, a total of 62 pairs of same-sexed twin infants given birth in four major general teaching hospitals in Taipei City were studied. Based on placentation and 12 red blood cell antigens, 44 MZ and 18 DZ pairs were identified. Temperament was assessed at the age of six months by the Chinese edition of Carey's Temperament scale. Significant genetic variance was observed for activity level, approach or withdrawal, intensity of reaction, quality of mood, and threshold of responsiveness, with a heritability of 0.64, 0.56, 0.74, 0.39, and 0.45, respectively. There was no significant intrapair difference in temperamental characteristics between monochorionic and dichorionic MZ twins.

Female↗
PubMed1990

Chronological changes in genetic variance and heritability of systolic and diastolic blood pressure among Chinese twin neonates.

In order to examine the chronological changes in genetic variance and heritability of arterial systolic and diastolic blood pressure (SBP and DBP of Chinese infants in Taiwan, a total of 339 same-sexed twin neonates born in four major general teaching hospitals in Taipei City were studied. Based on placentation and 12 red blood cell antigens, 274 monozygotic (MZ) and 65 dizygotic (DZ) twin pairs were identified and followed up to the age of one year. Both SBP and DBP were measured by Doppler blood pressure monitor. Within-pair mean squares of SBP and DBP were consistently smaller in MZ than DZ twins at ages one month and over. The findings remained unchanged after the adjustment for the effects of age, sex, gestational age, placentation and physical state during blood pressure measurement. Falconer's heritability indices for adjusted SBP and DBP at ages two months and over ranged from 0.29 to 0.55 and from 0.27 to 0.45, respectively. The study indicates an important genetic influence on blood pressure during infancy.

Blood Pressure↗
PubMed1990

Genetic variance and heritability of serum cholesterol and triglycerides among Chinese twin neonates.

In order to examine the genetic variance and heritability of serum total cholesterol, high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C) and triglycerides, a total of 349 pairs of same-sexed twin neonates born in four major general teaching hospitals in Taipei City were studied. Based on the placental pattern and 12 red blood cell antigens, 271 monozygotic (MZ) and 78 dizygotic (DZ) twin pairs were identified. There was a significant genetic variance for total cholesterol, HDL-C, LDL-C, and triglycerides both unadjusted and adjusted for sex, gestational age and placentation. The unadjusted heritability of total cholesterol, HDL-C, LDL-C, and triglycerides was 0.59, 0.30, 0.25 and 0.75, respectively; while the corresponding adjusted heritability was 0.74, 0.38, 0.31, and 0.49, respectively. Intrapair variance of serum lipids was not significantly different between monochorionic and dichorionic MZ twins.

China↗
PubMed1989

Color flow mapping in perimembranous ventricular septal defect with left ventricular-to-right atrial shunts.

The natural history of ventricular septal defect (VSD) varies with the exact location of the defect and also with the tissue changes surrounding it. Seven cases of perimembranous trabecular VSD were noted during color Doppler echocardiographic examination to have left ventricular-to-right atrial (LV-to-RA) shunts in association with aneurysmal transformation of VSD. Repeated cardiac catheterization documented the role of aneurysmal transformation in the increase of LV-to-RA shunts. A VSD located near the antero-septal commissure was diagnosed in all cases by echocardiography from the apical 5-chamber and parasternal inflow views. Echocardiographic signs of LV-to-RA shunts are high velocity backward turbulence in the RA without the presence of an elevated right ventricular systolic pressure and a two-directional turbulence through the "transformed" VSD. Corrective surgery confirmed the diagnosis in one case. Another case was complicated by an episode of viridans streptococcal endocarditis. The significance of LV-to-RA shunts in perimembranous trabecular VSD remains unknown.

Child↗
PubMed1989

Reconstruction of right ventricular outflow tract by autologous pericardial tri-semilunar valve with sinus of Valsalva: report of a case with absent pulmonary valve.

The choice of a valved conduit or a valve in the right ventricular outflow tract remains a problem. We propose to reconstruct the pulmonary valve inside the patient's own pulmonary trunk by autologous pericardium in tri-semilunar fashion with concomitant formation of the sinus of Valsalva and commissure. This operation was carried out on a 7-year-old girl suffering from Fallot's tetralogy with an absent pulmonary valve. The ventricular septal defect was repaired and the pulmonary valve reconstructed as above. The postoperative cross-sectional echocardiogram, color Doppler echocardiogram and angiogram showed a pliable tri-semilunar valve across the pulmonary outflow tract without regurgitation. It is concluded that firstly, the sinus of Valsalva is indispensable for a stentless semilunar valve to be competent; secondly, reconstruction of the semilunar valve inside the pulmonary trunk by autologous pericardium is recommended for the absent pulmonary valve syndrome, but the long-term fate of this pericardial valve awaits further evaluation.

Child↗
PubMed1988

Clinical implications of atrial isomerism.

Right atrial isomerism or left atrial isomerism is frequently diagnosed as situs ambiguous without further discrimination of the specific morbid anatomy. Thirty six cases of right atrial isomerism and seven cases of left atrial isomerism were collected from the records and pathological museum at the National Taiwan University Hospital. There was a necropsy report for 18 cases. In all patients one or more of the following conditions was met: (a) isomeric bronchial anatomy, (b) echocardiographic and angiocardiographic evidence of isomerism, and (c) surgical or necropsy evidence of abnormal atrial anatomy. An anomalous pulmonary venous connection was present in 55% of patients with right atrial isomerism; in left atrial isomerism one case (14%) had a partial anomalous pulmonary venous connection. Forty per cent of cases of anomalous pulmonary venous connection with right atrial isomerism had obstruction. Six (86%) of seven cases with left atrial isomerism had an ambiguous biventricular atrioventricular connection. In contrast, univentricular atrioventricular connection (26 of 36, 72%) was significantly more common in right atrial isomerism. A common atrioventricular valve was the most frequent mode of connection in both forms. Two discrete atrioventricular valves were significantly more common in left atrial isomerism. Atrioventricular valve regurgitation was detected in 14 cases. Double outlet right ventricle was the most common type of ventriculoarterial connection. The most commonly cited causes of death after either palliative or definitive operation were undetected anomalous pulmonary venous connection, pulmonary venous stricture, and uncorrected atrioventricular valve or aortic regurgitation complicated by abnormal coagulation. Although the prognosis is poor, successful operation depends on knowledge of the precise anatomical arrangement associated with atrial isomerism.

Abnormalities, Multiple↗