401
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Tai YT, Fong PC, Lau CP, Chow WH, Cheng CH. Reentrant fascicular tachycardia with cycle length alternans: insights into the tachycardia mechanism and origin. Pacing Clin Electrophysiol 1990; 13:900-7. [PMID: 1695747 DOI: 10.1111/j.1540-8159.1990.tb02127.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
This report details the electrophysiology of a unique case of reentrant fascicular tachycardia in a patient without structural heart disease. Persistent cycle length alternans, with constant fluctuation in alternate RR intervals, occurred during tachycardia. A distinct mode of spontaneous termination of tachycardia was observed. The findings were consistent with the presence of decremental conduction properties in the tachycardia circuit or decremental dual functional pathways within one limb of the circuit. These observations provide further evidence in support of a fascicular origin of the tachycardia.
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402
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Leung WH, Wong KL, Lau CP, Wong CK, Cheng CH, Tai YT. Doppler echocardiographic evaluation of left ventricular diastolic function in patients with systemic lupus erythematosus. Am Heart J 1990; 120:82-7. [PMID: 2360520 DOI: 10.1016/0002-8703(90)90163-r] [Citation(s) in RCA: 32] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Subclinical myocardial involvement frequently occurs in patients with systemic lupus erythematosus (SLE). In this study, left ventricular diastolic function was assessed in 58 patients (54 female and 4 male; mean age 32 +/- 11 years) and in 40 sex-matched and age-matched healthy control subjects (37 female and 3 male; mean age 33 +/- 9 years) by means of pulsed Doppler echocardiography. All subjects had no clinical evidence of overt myocardial disease or abnormal left ventricular systolic function. Compared with the control group, patients with SLE had significantly prolonged isovolumic relaxation time (62 +/- 12 vs 80 +/- 14 msec; p less than 0.01), reduced peak early diastolic flow velocity (peak E) (82 +/- 18 vs 76 +/- 16 cm/sec; p less than 0.05), increased peak late diastolic flow velocity (peak A) (45 +/- 7 vs 53 +/- 8 cm/sec; p less than 0.01), reduced E/A ratio (1.81 +/- 0.32 vs 1.46 +/- 0.29; p less than 0.001), and lower deceleration rate of early diastolic flow velocity (EF slope) (489 +/- 151 vs 361 +/- 185 cm/sec2; p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)
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403
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Leung WH, Wong KL, Lau CP, Wong CK, Cheng CH. Cardiac abnormalities in systemic lupus erythematosus: a prospective M-mode, cross-sectional and Doppler echocardiographic study. Int J Cardiol 1990; 27:367-75. [PMID: 2351496 DOI: 10.1016/0167-5273(90)90294-f] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
A prospective M-mode, cross-sectional and Doppler echocardiographic study was performed on 75 patients with systemic lupus erythematosus and 60 sex- and age-matched control subjects. Compared with the control group, patients with lupus had an increased prevalence of echocardiographic abnormalities. These included pericardial effusion and/or thickening (37%), left ventricular hypertrophy (12%), global left ventricular hypokinesis (5%), segmental abnormalities of left ventricular wall motion (4%), right ventricular enlargement (4%), focal verrucous valvar thickening (12%), gross valvar thickening and dysfunction (8%), mitral regurgitation (25%) and aortic regurgitation (8%). Two patients with gross mitral valvar thickening and dysfunction subsequently underwent valvar replacement. Correlation between echocardiographic abnormalities and clinical parameters showed that pericardial effusion was significantly associated with pericardial pain (P less than 0.05) and active disease (P less than 0.001), and left ventricular hypertrophy with systemic hypertension (P less than 0.05). Thus, there was a high prevalence of cardiac abnormalities, especially pericardial and valvar lesions, in patients with systemic lupus erythematosus. Echocardiography is invaluable in identifying these abnormalities and should be used routinely for cardiac evaluation of these patients.
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404
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Wong CK, Lau CP, Cheng CH, Leung WH, Pun KK, Nicholls MG. Effects of ventricular pacing on atrial natriuretic peptide levels during submaximal exercise in complete atrioventricular block. Am J Cardiol 1990; 65:1400-1. [PMID: 2140490 DOI: 10.1016/0002-9149(90)91336-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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405
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Leung WH, Lau CP, Tai YT, Wong CK, Cheng CH. Candida right ventricular mural endocarditis complicating indwelling right atrial catheter. Chest 1990; 97:1492-3. [PMID: 2347241 DOI: 10.1378/chest.97.6.1492] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Catheter-associated candidemia is a common problem in immunocompromised patients. A leukemic patient had Candida right ventricular mural endocarditis complicating an indwelling right atrial catheter. To our knowledge, this is the first reported case of Candida right ventricular mural vegetation visualized by two-dimensional echocardiography.
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406
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Lau CP, Leung WH, Wong CK, Tai YT, Cheng CH. A new pacing method for rapid regularization and rate control in atrial fibrillation. Am J Cardiol 1990; 65:1198-203. [PMID: 2337029 DOI: 10.1016/0002-9149(90)90973-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
In 15 patients with atrial fibrillation (AF), a single right ventricular extrastimulus (intercalated pacing) was delivered after every sensed conducted beat resulting in a reduction in rate. This method was used in 10 patients with lone AF and the average success rate of inducing coupling was 86 +/- 14% (range 64 to 100), using a mean coupling interval of 232 +/- 28 ms (range 175 to 290). During intercalated pacing, the pulse rate of AF was reduced (from 137 +/- 26 to 75 +/- 14 beats/min, p less than 0.001). Intercalated pacing resulted in enhancement of mean stroke volume (28 +/- 6 vs 44 +/- 10 ml in AF, p less than 0.0001), pulse pressure and the pulse-to-pulse regularity. Both the systolic and diastolic arterial pressures were regularized. The reduction in pulse rate during intercalated pacing was determined by the coupling interval, and the induction of concealed ventriculoatrial conduction (82 +/- 44 ms). Myocardial lactate extraction was similar during AF and short-term intercalated pacing (28 +/- 10 vs 25 +/- 9%, difference not significant). In 5 patients with severe mitral stenosis in AF, intercalated pacing resulted in an improvement in the cardiac output (3.1 +/- 0.2 vs 3.4 +/- 0.2 liters/min, p less than 0.04), a reduction in the gradient across the mitral valve (16 +/- 8 vs 10 +/- 5 mm Hg, p less than 0.02), and a reduction in pulmonary arterial and wedge pressures. This new pacing method thus achieved rapid temporary control of rate, regularity and cardiac hemodynamics during AF, which were more prominent in patients with mitral stenosis and restricted left ventricular filling.
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407
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Leung WH, Lau CP, Wong CK, Cheng CH, Tai YT, Lim SP. Improvement in exercise performance and hemodynamics by labetalol in patients with idiopathic dilated cardiomyopathy. Am Heart J 1990; 119:884-90. [PMID: 2181841 DOI: 10.1016/s0002-8703(05)80327-8] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Labetalol, a combined alpha- and beta-blocking agent, was administered to 12 patients (mean age 55 years) with idiopathic dilated cardiomyopathy to examine its effects on symptomatology and exercise performance. Studies were performed before treatment, after 8 weeks of placebo, and after 8 weeks of labetalol therapy in a randomized, crossover, double-blind design. The mean (+/- SEM) dose of labetalol for the group was 275 +/- 29 mg. Compared to treatment with placebo, the maximum duration of symptom-limited exercise was significantly prolonged with labetalol (580 +/- 72 seconds to 683 +/- 71 seconds; p less than 0.005). Both the resting and peak exercise heart rate and systolic blood pressure were significantly reduced. Ascending aortic blood flow velocity was also measured by continuous-wave Doppler technique during exercise. Compared to placebo, treatment with labetalol conferred no significant change in cardiac output at rest but significantly improved cardiac output at maximum exercise (14 +/- 3%; p less than 0.001). Doppler-derived peak aortic flow velocity, acceleration, and flow velocity integral were also significantly improved at maximum exercise. Systemic vascular resistance, as derived from mean blood pressure/cardiac output, was reduced by 12 +/- 3% and 16 +/- 3% at rest and at maximum exercise, respectively. New York Heart Association functional class was improved (3.2 +/- 0.2 to 2.2 +/- 0.3; p less than 0.005). No major side effects from labetalol were encountered. Thus labetalol improves symptomatology, exercise capacity, and exercise hemodynamics and reduces systemic vascular resistance in patients with idiopathic dilated cardiomyopathy.
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408
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Leung WH, Wong KL, Lau CP, Wong CK, Cheng CH, Tai YT. Echocardiographic identification of mitral valvular abnormalities in patients with mixed connective tissue disease. J Rheumatol 1990; 17:485-8. [PMID: 2348428] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
To evaluate cardiac involvement in mixed connective tissue disease (MCTD), M-mode, 2-dimensional and pulsed Doppler echocardiography were performed in 17 patients with MCTD. Pericardial abnormalities were present in 4 patients (24%), including small pericardial effusion (less than 1 cm) in 2 patients and pericardial thickening in 2 patients. Verrucous thickening of the mitral valve was detected in 2 patients (12%) by 2-dimensional echocardiography. Pulsed Doppler echocardiography revealed the presence of mild mitral regurgitation in one of them. To our knowledge, such mitral valve abnormalities have not been reported. Future larger studies are needed in order to evaluate the incidence and natural evolution of these mitral valvular abnormalities.
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409
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Lau CP, Leung WH, Wong CK, Cheng CH. Haemodynamics of induced atrial fibrillation: a comparative assessment with sinus rhythm, atrial and ventricular pacing. Eur Heart J 1990; 11:219-24. [PMID: 2318225 DOI: 10.1093/oxfordjournals.eurheartj.a059687] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The haemodynamics and myocardial lactate consumption during induced atrial fibrillation (AF) were studied in 10 patients with paroxysmal AF. Their mean age (+/- SD) was 61 +/- 5 years and none had clinical evidence of ischaemic or rheumatic heart disease. Compared with sinus rhythm, the onset of AF was associated with a reduction in systolic blood pressure (152 +/- 13 mmHg) in AF vs 169 +/- 23 mmHg in sinus rhythm, P less than 0.01). There was no consistent change in cardiac output at the onset of AF compared with sinus rhythm, but the cardiac output was lower compared with regular atrial pacing at rates similar to those of induced AF (3.85 +/- 0.76 vs 4.38 +/- 0.89 l min-1, P less than 0.02). Compared with sinus rhythm or rate-matched atrial pacing, AF was associated with an elevated pulmonary arterial pressure (24.2 +/- 5.6 mmHg in AF vs 17.9 +/- 14.4 mmHg in sinus rhythm, P less than 0.01) and pulmonary arterial wedge pressure (18.6 +/- 5.6 vs 9.7 +/- 3.9 mmHg, P less than 0.01). The haemodynamic changes during AF were similar to those seen during regular ventricular pacing at an equivalent rate, although the latter was associated with a lower systolic blood pressure (152 +/- 13 mmHg in AF vs 136 +/- 25 mmHg in ventricular pacing, P less than 0.05) and higher right atrial pressure (8.2 +/- 4.4 vs 11.5 +/- 7.5 mmHg respectively, P less than 0.05), presumably due to the deleterious effects of cannon 'a' waves.(ABSTRACT TRUNCATED AT 250 WORDS)
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410
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Chow WH, Cheung KL, Tai YT, Cheng CH. Successful percutaneous balloon valvuloplasty of a stenotic tricuspid bioprosthesis. Am Heart J 1990; 119:666-8. [PMID: 2309607 DOI: 10.1016/s0002-8703(05)80291-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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411
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Barnes NM, Cheng CH, Costall B, Naylor RJ. The relative abilities of MPTP and MPP+ to compete with [3H]dopamine for the rat and marmoset striatal dopamine uptake site. Biochem Pharmacol 1990; 39:809-11. [PMID: 2306287 DOI: 10.1016/0006-2952(90)90166-i] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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412
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Lau CP, Lee CP, Wong CK, Cheng CH, Leung WH. Rate responsive pacing with a minute ventilation sensing pacemaker during pregnancy and delivery. Pacing Clin Electrophysiol 1990; 13:158-63. [PMID: 1689831 DOI: 10.1111/j.1540-8159.1990.tb05065.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
A minute ventilation sensing rate responsive pacemaker was implanted in a 29-week pregnant woman with symptomatic complete atrioventricular (AV) block under echocardiographic and electrocardiographic (ECG) guidance. Satisfactory rate responses during a submaximal treadmill exercise test and daily activities were achieved. The course of pregnancy and cesarean section is discussed. During the cesarean section and after the delivery of the baby, changes in the ventilator settings confirmed that the pacing rate was closely correlated with both the tidal volume (r = 0.94, P less than 0.01) and the respiratory rate (r = 0.93, P less than 0.05).
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413
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414
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Abstract
Mitral stenosis is a well known cause of hemoptysis; however, sudden death due to fatal massive pulmonary hemorrhage is an extremely rare complication. In this report, we describe a 28-year-old female with severe mitral stenosis who died suddenly due to such complication. A review of the literature shows such complication is extremely rare and unpredictable. We recommend that patients with severe mitral stenosis and history of hemoptysis be considered as candidates for early surgical intervention.
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415
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Tai YT, Chow WH, Cheng CH. Effect of adenosine on atrioventricular (AV) conduction. Pacing Clin Electrophysiol 1990; 13:249-52. [PMID: 1689842 DOI: 10.1111/j.1540-8159.1990.tb05076.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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416
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Rodrigo CR, Rosenquist JB, Cheng CH. Cardiac dysrhythmias with midazolam sedation. Anesth Prog 1990; 37:20-3. [PMID: 2077981 PMCID: PMC2163530] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
A randomized cross-over study was made of 32 young healthy Hong Kong Chinese to compare the incidence and nature of dysrhythmias that occurred during third molar surgery done under local anesthesia, alone or supplemented with midazolam sedation. The incidence of dysrhythmias during surgery was not significantly different during the two procedures. However prior to surgery, 25% of the patients had dysrhythmias during sedation with midazolam. The majority of dysrhythmias were infrequent unifocal ventricular ectopics. During sedation with midazolam it may be beneficial to monitor the electrocardiogram, especially in high risk patients such as those suffering from ischaemic heart disease, cardiomyopathy, and those on antidysrhythmic drugs.
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417
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Leung WH, Wong KL, Lau CP, Wong CK, Cheng CH, Tai YT. Doppler-echo evaluation of left ventricular diastolic filling in patient with mixed connective tissue disease. Cardiology 1990; 77:93-100. [PMID: 2397491 DOI: 10.1159/000174589] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Left ventricular diastolic function was assessed in 17 patients (2 males and 15 females; mean age 44 +/- 9 years) with mixed connective tissue disease (MCTD) and 18 sex- and age-matched healthy control subjects (2 males and 16 females; mean age 44 +/- 8 years) by means of M-mode and pulsed Doppler echocardiography. None had clinical evidence of overt myocardial disease or abnormal left ventricular systolic function. Compared with the control group, patients with MCTD had a significantly longer isovolumic relaxation time (IVRT) (59 +/- 7 versus 70 +/- 12 ms; p less than 0.01), a lower peak early diastolic flow velocity (E) (0.79 +/- 0.10 versus 0.70 +/- 0.07 m/s; p less than 0.005), a higher peak late diastolic flow velocity due to atrial contraction (A) (0.47 +/- 0.08 versus 0.54 +/- 0.08 m/s; p less than 0.05) and a reduced E/A ratio (1.72 +/- 0.37 versus 1.33 +/- 0.26; p less than 0.005). Although there was no significant correlation of left ventricular diastolic filling indexes with age, heart rate, left ventricular end-diastolic and end-systolic dimensions, interventricular septal and left ventricular posterior wall thickness, and fractional shortening, the duration of illness was significantly related to IVRT (r = 0.62; p less than 0.01), peak A (r = 0.79; p less than 0.001) and velocity half-time (r = 0.54; p less than 0.05). The results suggest the presence of an abnormal left ventricular diastolic filling pattern in patients with MCTD and may represent myocardial involvement in this disease.
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418
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Abstract
'Leopard' syndrome is a rare inherited disorder associated with a high prevalence of cardiac abnormalities. General anaesthesia for dental treatment in a patient who had cardiomyopathy and bizarre electrocardiographic abnormalities associated with this syndrome is described. A thorough cardiac assessment is advised in a patient with multiple lentigines, although no clinical symptoms or signs may be found. Even if no cardiac abnormality is found before it is better to re-assess the patient, since abnormalities may develop later. The assessment should be repeated if any abnormality was detected before but without clinical significance, since the disease is progressive and may progress more rapidly in some patients than in others.
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419
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Wong CK, Pun KK, Cheng CH, Lau CP, Leung WH, Chan MK, Yeung DW. Hypocalcemic heart failure in end-stage renal disease. Am J Nephrol 1990; 10:167-70. [PMID: 2349961 DOI: 10.1159/000168073] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
A 37-year-old woman presented with hypocalcemic heart failure complicating end-stage renal disease. Heart failure persisted despite conventional therapy but improved after correction of hypocalcemia. Continuous monitoring of left ventricular function by radionuclide study during calcium replacement showed dramatic improvement. Our case showed that hypocalcemia could be a rare but reversible cause of frank heart failure in uremic patients.
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420
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Wong CK, Lau CP, Leung WH, Cheng CH. The use of nifedipine in patients with Eisenmenger's syndrome complicating patency of the arterial duct. Int J Cardiol 1989; 25:173-8. [PMID: 2807605 DOI: 10.1016/0167-5273(89)90104-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Nifedipine has a vasodilatory effect on both the systemic and the pulmonary circulation. Its preferential effect on reducing the pulmonary vascular resistance has been studied in patients with primary pulmonary hypertension. In 4 patients with the Eisenmenger's syndrome complicating patency of the arterial duct (ductus arteriosus), we have studied the possibility of this selective pulmonary vasodilatory effect of nifedipine in reducing the right-to-left shunting. The degree of differential cyanosis was taken to reflect the right-to-left shunting. This was assessed continuously by 2 pulse oximeters applied to the right arm and leg. After sublingual nifedipine, the oxygen saturation of the right leg increased from pretreatment value of 79 +/- 5% (mean +/- SEM) to a maximum of 84 +/- 3% (P less than 0.01). Such a beneficial effect was maximal in the first 2 hours. On maintenance therapy, symptom-limited cycle ergometry showed increased exercise duration with comparable degrees of arterial desaturation and there was symptomatic improvement. This improvement disappeared on changing to placebo. It was concluded that nifedipine reduced right-to-left shunting and improved symptomatology.
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421
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Leung WH, Tai YT, Lau CP, Wong CK, Cheng CH, Chan TK. Cardiac tamponade complicating leukaemia: immediate chemotherapy or pericardiocentesis? Postgrad Med J 1989; 65:773-5. [PMID: 2616408 PMCID: PMC2429848 DOI: 10.1136/pgmj.65.768.773] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Although leukaemic infiltration of the pericardium is frequently observed at post-mortem, clinically evident cardiac tamponade is rare. Two cases of cardiac tamponade complicating leukaemia are presented. One patient had cardiac tamponade as the initial presentation of acute lymphoblastic leukaemia and experienced complete resolution of the pericardial effusion within 6 days after chemotherapy without therapeutic pericardiocentesis. The other patient with chronic myeloid leukaemia developed cardiac tamponade requiring pericardiocentesis as the first sign of acute blastic transformation. The roles of early chemotherapy and pericardiocentesis in managing this complication are discussed.
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MESH Headings
- Antineoplastic Combined Chemotherapy Protocols/therapeutic use
- Blast Crisis/pathology
- Cardiac Tamponade/etiology
- Cardiac Tamponade/surgery
- Cardiac Tamponade/therapy
- Drainage
- Evaluation Studies as Topic
- Female
- Humans
- Leukemia, Myelogenous, Chronic, BCR-ABL Positive/complications
- Leukemia, Myelogenous, Chronic, BCR-ABL Positive/drug therapy
- Leukemia, Myelogenous, Chronic, BCR-ABL Positive/pathology
- Leukemia-Lymphoma, Adult T-Cell/complications
- Leukemia-Lymphoma, Adult T-Cell/drug therapy
- Middle Aged
- Punctures
- Recurrence
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422
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Abstract
Congenital coronary aneurysm is a rare disorder and most of the previously reported cases were necropsy findings, usually in association with other coronary artery abnormalities. Although rupture and thrombosis were the most common causes of death, the management of this condition has not been well defined. A patient with a right coronary artery aneurysm which remained stable over 8 years is described. It is suggested that the disease might be compatible with long-term survival.
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423
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Lau CP, Wong CK, Leung WH, Cheng CH, Lo CW. A comparative evaluation of a minute ventilation sensing and activity sensing adaptive-rate pacemakers during daily activities. Pacing Clin Electrophysiol 1989; 12:1514-21. [PMID: 2476780 DOI: 10.1111/j.1540-8159.1989.tb06156.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Most studies evaluating the rate response of adaptive-rate pacemakers have been based on treadmill or bicycle exercise. These studies disregard the fact that few pacemaker recipients voluntarily undertake such activities. The rate responses of nine patients (mean age 62 years, range 33-79 years) with implanted minute ventilation sensing (Meta) pacemakers were studied. The indications for pacing were complete heart block (seven patients), sick sinus syndrome (one patient), and five nodal disease (one patient). Significant improvement in maximum distance covered during a 12-minute walking test was observed in the rate adaptive compared to the VVI pacing mode (989 +/- 104 vs 921 +/- 90 m, P less than 0.02). The rate responses of this pacemaker during daily activities were recorded with telemetry during a variety of structured daily activities. The rate responses were also compared to those of an externally attached Activitrax pacemaker in each patient and to a group of ten age and sex matched volunteers. For less strenuous activities such as walking, descending stairs, washing, and bed making, both pacemakers achieved adequate rate responses compared to normal subjects. For more strenuous activities, the Activitrax pacemaker failed to achieve an adequate rate response. For example, the pacing rate achieved on ascending stairs was lower than that achieved on descending stairs (92 +/- 3 vs 102 +/- 3 bpm, P less than 0.02). The direction of rate responses was more appropriate for the Meta pacemaker. Similar to the normal subjects, the maximum rate was reached before the end of an activity with the Activitrax pacemaker.(ABSTRACT TRUNCATED AT 250 WORDS)
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424
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Wong CK, Lau CP, Cheng CH, Leung WH, Chan TY, Pun KK. Elevated atrial natriuretic peptide level in giant right atrium complicating Marfan's syndrome. Eur Heart J 1989; 10:863-4. [PMID: 2530089 DOI: 10.1093/oxfordjournals.eurheartj.a059583] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
We report a rare case of giant right atrial dilatation in a patient with Marfan's syndrome complicated by severe tricuspid regurgitation. Interestingly, the right atrial pressure was normal, but the atrial natriuretic peptide level was markedly elevated. We suggest that the underlying connective tissue abnormality had allowed extensive atrial distension which by causing an increased intramural tension according to Laplace's law stimulated atrial natriuretic peptide secretion.
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425
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Abstract
Isolated interrupted aortic arch is a rare congenital cardiac disorder believed at one time to be incompatible with life once the ductus arteriosus closed. To our knowledge, only 12 cases have been reported in the literature and mostly in children. The diagnosis was made in all of them by catheterization. We report the first adult patient with an asymptomatic interrupted aortic arch diagnosed by computed tomography.
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426
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Abstract
Cor triatriatum presenting in adulthood is extremely rare. We describe a case of adult cor triatriatum in which the diagnosis was initially masked by the concomitant existence of COPD. Cardiac catheterization revealed only slightly elevated pulmonary wedge pressure despite severe pulmonary arterial hypertension. Both the primary lung disease and cor triatriatum greatly accentuated the pulmonary vascular disease which led to a reduction of pulmonary blood flow. Consequently, pulmonary venous obstruction was masked and was not reflected by measuring pulmonary wedge pressure. The diagnosis was made by two-dimensional echocardiography and left ventriculography.
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427
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Cheng CH, DeVries AL. Structures of antifreeze peptides from the antarctic eel pout, Austrolycicthys brachycephalus. BIOCHIMICA ET BIOPHYSICA ACTA 1989; 997:55-64. [PMID: 2752054 DOI: 10.1016/0167-4838(89)90135-0] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The antarctic eel pout, Austrolycicthys brachycephalus, synthesizes two predominant antifreeze peptides (AFPs) which, based on purification yields, make up about 94 and 6%, respectively, of the antifreezes in its serum. The amino acid sequences of these two AFPs, AB1 and AB2, were determined using automated sequencing, and compositional analyses of peptide fragments from enzymatic digests, and verified by molecular masses obtained with Fast Atom Bombardment Mass spectrometry. Substantial homologies in amino acid sequence exist between the AFPs of Austrolycicthys and those of other Southern and Northern eel pouts. 72% of the residues of AB1, and 84% of AB2, are identical to those of an AFP from another antarctic eel pout, Rhigophila dearborni. Between AB1 and AB2, 83% of the residues are identical. Secondary structure data based on circular dichroism studies indicated AB1 to be a random chain, but a sharp thermal transition of CD spectra around 30 degrees C suggested the presence of definite secondary or tertiary structure.
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428
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Lau CP, Wong CK, Leung WH, Cheng CH. Ultrasonic assisted permanent pacing in a patient with severe pulmonary tuberculosis. Pacing Clin Electrophysiol 1989; 12:1131-6. [PMID: 2476750 DOI: 10.1111/j.1540-8159.1989.tb01935.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
A 67-year-old male patient with previous history of pulmonary tuberculosis presented with syncope due to complete heart block. Collapse of the right lung and deviation of the heart to the right chest had prevented visualization of the cardiac silhouette by fluoroscopy. Successful endocardial permanent pacing using a passive fixation electrode was achieved with the help of ultrasonic visualization of the cardiac chambers.
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429
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Leung WH, Wong KK, Lau CP, Wong CK, Cheng CH, So KF. Myocardial involvement in Churg-Strauss syndrome: the role of endomyocardial biopsy. J Rheumatol 1989; 16:828-31. [PMID: 2528635] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
A Chinese adult with Churg-Strauss syndrome with prominent cardiac involvement is described. The myocardial impairment initially showed good response to corticosteroid and cyclophosphamide. However, the cardiac status deteriorated later despite the absence of disease activity elsewhere. Endomyocardial biopsy was performed to determine the possibility of isolated myocardial relapse in case additional immunosuppression would be beneficial. Histology of the endomyocardial biopsy revealed myocardial fibrosis. Since cardiac involvement is the major cause of mortality in this condition and delayed treatment can lead to intractable cardiac failure, we advocate that endomyocardial biopsy should be performed more liberally and possibly serially to assess the disease activity in the myocardium. Immunosuppression may then be adjusted. To our knowledge, the occurrence of Churg-Strauss syndrome in Chinese has not been reported in the English literature.
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430
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Chow WH, Cheung LK, Cheng CH. Total occlusion of the left main coronary artery in a Hong Kong Chinese. Chin Med J (Engl) 1989; 102:227-9. [PMID: 2503311] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Total occlusion of the left main coronary artery (LMCA) is a rare finding in patients with stable angina pectoris. To the best of our knowledge, it has not been described in Hong Kong Chinese before. In this paper, we report the clinical and angiographic findings of a Hong Kong Chinese with this condition treated in our unit.
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431
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Cheng CH, Lian JD, Yang YF, Shu KH, Lu YS, Chen DL. Persistant abnormal serum parathyroid hormone after renal transplantation: correlation between renal graft function. ZHONGHUA YI XUE ZA ZHI = CHINESE MEDICAL JOURNAL; FREE CHINA ED 1989; 43:81-4. [PMID: 2670141] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Secondary hyperparathyroidism in uremia renal transplantation. We studied the i-PTH (immunoactive parathyroid hormone) of nineteen immunoactive parathyroid hormone) of nineteen patients before and after renal transplantation with average of 20 months post transplantation. In group I patients with normal i-PTH serum level had an significant lower serum level of creatinine than Group II with elevated abnormal i-PTH. While the calcium and phosphorus showed no significant difference between group I and Group II patients. We suggested that abnormal serum i-PTH level after renal transplantation after one year was closely related to renal graft function. This group of abnormal serum i-PTH should be closely monitored for their renal graft function.
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432
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Wong CK, Leung WH, Cheng CH, Lau CP, Cheung DL. Myxomatous mitral valve degeneration complicating asymptomatic cor triatriatum. Clin Cardiol 1989; 12:48-50. [PMID: 2912609 DOI: 10.1002/clc.4960120110] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Cor triatriatum presenting in adulthood is extremely rare. This paper reports a case of cor triatriatum initially masquerading as mitral stenosis, which was later complicated by myxomatous mitral valve degeneration with severe regurgitation, which necessitated mitral valvular replacement. To the authors' knowledge, such a combination has not been reported in the literature.
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433
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Shu KH, Lian JD, Yang YF, Lu YS, Cheng CH, Chen DL. Plasma zinc level in hemodialysis, continuous ambulatory peritoneal dialysis and renal transplantation. TAIWAN YI XUE HUI ZA ZHI. JOURNAL OF THE FORMOSAN MEDICAL ASSOCIATION 1987; 86:1251-5. [PMID: 3327910] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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434
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Napier MA, Lipari MT, Courter RG, Cheng CH. Epidermal growth factor receptor tyrosine kinase phosphorylation of glucose-6-phosphate dehydrogenase in vitro. Arch Biochem Biophys 1987; 259:296-304. [PMID: 3122660 DOI: 10.1016/0003-9861(87)90496-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The specific tyrosine phosphorylation of glucose-6-phosphate dehydrogenase (G6PDH) by the epidermal growth factor (EGF) receptor in vitro is demonstrated. The Km values of the substrate G6PDH and of ATP for the receptor tyrosine kinase were ca. 1 and 10 microM, respectively. The rate of phosphorylation was EGF dependent, with a four-fold increase in Vmax in the presence of EGF. The phosphorylation was stimulated maximally by 0.2 microM or greater EGF, with an ED50 of ca. 20 nM which is consistent with the affinity of the solubilized receptor for EGF. Using conditions of 5 microM G6PDH, 100 microM ATP, 5 mM Mg2+, and 1 mM Mn2+, up to 0.3 mol phosphate was incorporated into 1 mol of the 55-kDa subunit of Baker's yeast G6PDH. Tryptic peptide mapping revealed several unique phosphopeptides for both Baker's yeast and bovine adrenal G6PDH. The patterns of phosphopeptides for a given enzyme were identical for basal and EGF-stimulated phosphorylation.
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435
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Schrag JD, Cheng CH, Panico M, Morris HR, DeVries AL. Primary and secondary structure of antifreeze peptides from arctic and antarctic zoarcid fishes. BIOCHIMICA ET BIOPHYSICA ACTA 1987; 915:357-70. [PMID: 3477289 DOI: 10.1016/0167-4838(87)90021-5] [Citation(s) in RCA: 32] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Antifreeze peptides were isolated from Rhigophila dearborni, an antarctic eel pout, and Lycodes polaris, an arctic eel pout (both from the family Zoarcidae). The primary structures of two peptides, one from each species, were determined using a combination of Edman degradation and mass spectrometric techniques. The two sequences show a high degree of homology with nearly 80% of the residues being identical. These peptides are also homologous to antifreeze peptides from a third eel pout which inhabits the north Atlantic Ocean. The CD spectra of all of these peptides are also very similar. Unlike the antifreeze peptides of cottid fishes, the structures of antifreeze peptides from zoarcid fishes appear to be highly conserved, despite the large geographic distances which separate the different species. The zoarcid peptides also appear to have structures very different from other fish antifreezes.
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436
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Ng TB, Hon WK, Cheng CH, Su BX. Evidence for the presence of adrenocorticotropic and opiate-like hormones in the brains of two sea snakes, Hydrophis cyanocinctus and Lapemis hardwickii. Gen Comp Endocrinol 1986; 63:31-7. [PMID: 2876927 DOI: 10.1016/0016-6480(86)90178-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The brain acetone powders of the sea snakes Hydrophis cyanocinctus and Lapemis hardwickii were extracted with a mixture of acetone:water:hydrochloric acid (40:21:1 by volume) and the extracts were then added to a copious volume of acetone, in accordance with the method of C. H. Li (1952, J. Amer. Chem. Soc., 74, 2134) for preparing adrenocorticotropin and beta-endorphin from mammalian pituitaries. The resultant precipitate, designated acid acetone powder, possessed adrenocorticotropic activity as evidenced in its ability to stimulate corticosterone production in isolated rat adrenal decapsular cells and lipolysis in isolated hamster adipocytes, and in its cross-reactivity in an ACTH radioimmunoassay. The presence of opioid molecules was indicated by activity in opiate radioreceptor assay using either 3H-D-Ala2-D-Leu5 enkephalin or [3H]naloxone as ligand and rat brain membranes. The brain acetone powders possessed neither "lactogenic" nor "somatogenic" activity as evidenced by their inability to displace the primary ligand in the rat hepatic prolactin receptor- and growth hormone receptor-binding assays, respectively.
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437
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Pak RC, Tsim KW, Cheng CH. The role of neonatal and pubertal gonadal hormones in regulating the sex dependence of the hepatic microsomal testosterone 5-reductase activity in the rat. J Endocrinol 1985; 106:71-9. [PMID: 4020314 DOI: 10.1677/joe.0.1060071] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Heptic microsomal testosterone 5-reductase activity was approximately fourfold higher in adult female rats than in males. This discrepancy was only partly androgen-dependent since gonadectomy of male rats at 68 days of age resulted in only a partial increase of the enzyme activity. This increase was reversible by the administration of testosterone. Similar treatment, however, produced no effect in the female rat, indicating that there is a sex difference in testosterone responsivity. Castration of newborn male rats resulted in a marked increase in the basal enzyme activity. This increase was not affected by treating the adults with testosterone. Giving testosterone to male rats immediately after neonatal gonadectomy, or to newborn female rats, did not produce the male pattern of both the basal enzyme activity and the testosterone responsivity in adulthood. These results suggest that a brief exposure to neonatal androgen is not critical for the expression of the male type of enzyme activity, but that the continuous presence of the male gonads up to and including the pubertal period is essential. Exposure of pubescent female rats to testosterone during the period from 35 to 50 days of age resulted in a significant increase in testosterone sensitivity when tested at 90 days of age, suggesting that pubertal exposure to androgen is important for the expression of testosterone responsivity in adulthood. The sensitivity was potentiated when the animals were ovariectomized before puberty. Furthermore, the enzyme activity in prepubertally ovariectomized female rats was significantly lower than that in adult gonadectomized animals.(ABSTRACT TRUNCATED AT 250 WORDS)
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438
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Tsim KW, Pak RC, Cheng CH. Prolactin receptor in rat liver: sex difference in estrogenic stimulation and imprinting of the responsiveness to estrogen by neonatal androgen in male rats. Mol Cell Endocrinol 1985; 40:99-105. [PMID: 2989035 DOI: 10.1016/0303-7207(85)90163-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Rat hepatic prolactin receptor is regulated by sex steroids. A high level of the receptor was found in female rats but the level was nearly undetectable in males. Gonadectomy reduced the receptor level in females but increased the level in males. Administration of estradiol benzoate (0.05 mumoles/kg on alternate days subcutaneously for 9 days) to adult gonadectomized females increased the receptor level by 473% whereas the same treatment in adult gonadectomized males produced a more modest 276% increase. This sexually dimorphic pattern in the responsiveness to estrogen stimulation in adult rats appeared to be determined neonatally. Neonatal gonadectomy of male rats changed the hepatic response system to a more female pattern in adulthood. Replacement of testosterone (1.45 mumoles at days 1 and 3 after birth) to these neonatally gonadectomized male rats restored the male pattern. Diethylstilbestrol replacement (1.45 mumoles at days 1 and 3 after birth) to the neonatally gonadectomized male rats showed the same effect as neonatally administered testosterone. Scatchard analysis revealed that the observed changes in binding are related to changes in binding capacity but not affinity. Desaturation by 4 M MgCl2 indicated that the amount of endogenously bound hormone was negligible in our membrane preparations.
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439
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Tsim KW, Cheng CH. Evidence for the involvement of essential sulphydryl group in rat hepatic lactogenic receptor but not in somatogenic receptor. Mol Cell Endocrinol 1984; 38:61-6. [PMID: 6097490 DOI: 10.1016/0303-7207(84)90145-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Incorporation of p-chloromercuribenzene sulphonate (PCMBS) (1mM) in the assay medium for rat hepatic lactogenic receptor produced complete inhibition of binding of [125I]oPRL to the membrane. However, the presence of the thiol-reactive agent produced no effect on the binding of [125I]bGH to rat hepatic somatogenic receptor. Pretreatment of rat hepatic membrane with PCMBS inhibited the binding of [125I]oPRL but not that of [125I]bGH. The lactogenic receptor binding inhibition by PCMBS pretreatment was both concentration- and time-dependent, with complete inhibition at 0.5 mM for 60 min at 0 degrees C. Scatchard analysis of [125I]oPRL binding to membrane at 50% inhibition by PCMBS (0.11 mM) revealed that the binding capacity was decreased rather than the binding affinity. Furthermore, the inhibition of lactogenic receptor binding by PCMBS could be reversed by dithioerythritol (DTE) treatment. Following 80% inhibition by 0.2 mM PCMBS, full recovery of receptor binding was achieved at 6 mM DTE for 60 min at 0 degrees C. The 'recovered' membrane showed no difference from the control membrane in terms of binding capacity and affinity.
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440
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Cheng CH, Tsim KW, Wai MK, Pak RC. Rat hepatic prolactin receptor: pubertal exposure to sex steroids alters responsivity to testosterone. INTERNATIONAL JOURNAL OF PEPTIDE AND PROTEIN RESEARCH 1984; 23:521-7. [PMID: 6329976 DOI: 10.1111/j.1399-3011.1984.tb02753.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Administration of testosterone enanthate to adult female rats lowered the level of hepatic prolactin receptor. Pubertal exposure of intact female rats to testosterone enanthate at the dose used did not affect the level of hepatic prolactin receptor in adults. However, the responsivity of such treated rats to testosterone challenge in adulthood was enhanced. Prepubertal ovariectomy of female rats lowered the level of hepatic prolactin receptor in adulthood. Exposure of the ovariectomized rats during puberty to mestranol (ethynylestradiol 3-methyl ether) at the dose used did not restore the normal adult female rat's level of hepatic prolactin receptor. However, they did become more resistant to subsequent testosterone challenge in adulthood. Exposure of prepubescent ovariectomized rats to testosterone enanthate during puberty reduced the already diminished level of hepatic prolactin receptor further. In addition, these rats were rendered more responsive to testosterone challenge in adulthood.
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441
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Horne MK, Cheng CH, Wooten GF. The cerebral metabolism of L-dihydroxyphenylalanine. An autoradiographic and biochemical study. Pharmacology 1984; 28:12-26. [PMID: 6701184 DOI: 10.1159/000137938] [Citation(s) in RCA: 35] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The regional cerebral distribution of carbon-14 activity was studied using autoradiography following the intravenous administration of L-3,4-dihydroxyphenyl-(3-14C)-alanine (14C-L-dopa) to rats pretreated with carbidopa. 5 min after 14C-L-dopa administration, the regional cerebral distribution of carbon-14 varied with regional cerebral blood flow. From 45 min to 4 h after 14C-L-dopa administration, however, carbon-14 activity accumulated in a regionally selective manner which correlated (p less than 0.001) with the total endogenous catecholamine content of each region (n = 26). A prior unilateral lesion of the substantia nigra pars compacta markedly reduced the accumulation of carbon-14 in the ipsilateral, but not the contralateral, striatum at all times from 45 min to 4 h after 14C-L-dopa administration. Similarly, reserpine pretreatment selectively reduced the accumulation of carbon-14 in only those regions in which a marked accumulation occurred in controls after intravenous injections of 14C-L-dopa. Liquid chromatography with electrochemical detection was utilized to determine the tritium content of L-dopa and its metabolites in the striatum and cerebellum from 1 min to 4 h after the intravenous administration of 3H-L-dopa. 3H-dopamine, and subsequently 3H-dihydroxyphenylacetic acid and 3H-homovanillic acid, appeared only in the striatum. 3H-3-O-methyldopa levels rose simultaneously in the cerebellum and striatum. These results demonstrate a feasible approach for imaging dopamine neurons in man in vivo by positron emission tomography provided that L-dopa can be labeled with a positron-emitting isotope with sufficient specific activity. Furthermore, these results suggest that quantitative interpretation of the images is possible.
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442
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Pak RC, Tsim KW, Cheng CH. Pubertal gonadal hormones in modulating the testosterone dependency of hepatic aryl hydrocarbon hydroxylase in female rats. Pharmacology 1984; 29:121-7. [PMID: 6483958 DOI: 10.1159/000138002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
The responsiveness of the hepatic microsomal aryl hydrocarbon hydroxylase (AHH) to testosterone enanthate (TE; 2.5 mumol/kg/day for 9 days) was sex-dependent in adult rats, the enzyme being very resistant to TE in normal adult or ovariectomized females. Administration of testosterone propionate or diethylstilbestrol (1.45 mumol) to neonatal female rats at 1 and 3 days of age did not increase the responsivity to TE in adulthood. However, exposure of female rats to TE (5.0 mumol/kg/day) during the peripubertal period (35-50 days old) resulted in increased sensitivity to TE (+55.2%) when tested in adulthood. The responsivity was further potentiated (+109.3%) if the animals were ovariectomized at 28 days of age. Prepubescent ovariectomized females which received corn oil or estradiol benzoate (1.5 mumol/kg on alternate days) during puberty were not able to respond to TE significantly. These results suggest that the refractoriness of the hepatic AHH to testosterone in adult female rats is determined by the absence of testosterone, as well as the presence of estrogens, during puberty.
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443
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Cheng CH, Yang YC, Wu TY, Weng PS. Radiation control through licensing and intensive training. HEALTH PHYSICS 1982; 43:803-811. [PMID: 7152945 DOI: 10.1097/00004032-198212000-00003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Various types of intensive training courses to suit radiation workers in different fields were sponsored by both the Atomic Energy Council of Executive Yuan and the National Health Administration of Executive Yuan, Republic of China during the past seven years. During the years 1974-79, the number of radiation workers attending each training course, their age, sex and educational background are presented in detail. The typical course contents for both medical and non-medical radiation workers are given. A summary of the percentage of passes and failures of the final examination given at the end of each training course is also given. The present status of licensing for radiation facilities and workers is described, and its results are indicated. The successful control of ionizing radiation through this kind of intensive training and licensing is evidenced in the film badge records given by a centralized service laboratory located at the National Tsing Hua University.
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444
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Cheng CH, Wooten GF. Dopamine turnover estimated by simultaneous LCEC assay of dopamine and dopamine metabolites. JOURNAL OF PHARMACOLOGICAL METHODS 1982; 8:123-33. [PMID: 7144209 DOI: 10.1016/0160-5402(82)90066-3] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
The estimation of changes in tissue levels of dopamine (DA) and its metabolites has been employed to approximate the turnover rate or release of DA. We have developed an assay using high pressure liquid chromatography with electrochemical detection to quantify DA, dihydroxyphenylacetic acid (DOPAC), 3-methoxytyramine (3-MT), and homovanillic acid (HVA) simultaneously in brain homogenates. The assay is simple, inexpensive, rapid and accurate; the sensitivity of the assay for DA and DOPAC was 10 pg, for HVA 50 pg, and 200 pg for 3-MT. Apomorphine treatment resulted in a reduction in tissue levels of DOPAC and HVA, while haloperidol administration increased tissue levels of DOPAC and HVA. Neither drug treatment caused changes in DA levels. Administration of d-amphetamine 2.5 mg/kg S.C. resulted 1 hour later in increases in the striatal concentration of DA (57%) and 3-MT (44%) and decreases in DOPAC (40%) and HVA (39%). These data are consistent with the agonistic effect of apomorphine and antagonistic effect of haloperidol on DA autoreceptors and post-synaptic receptors. In the case of amphetamine, the increases in the levels of DA and 3-MT probably reflect the ability of d-amphetamine to induce DA release and block re-uptake. The reduction of DOPAC and HVA levels are consistent with the ability of d-amphetamine to competitively inhibit monoamine oxidase activity as well as the neuronal reuptake of DA. The simultaneous estimation of DA, DOPAC, 3-MT, and HVA should facilitate the understanding of dopaminergic drugs with complicated mechanisms of action.
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445
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Li CH, Ng TB, Cheng CH. Melanotropins: aldosterone- and corticosterone-stimulating activity in isolated rat adrenal cells. INTERNATIONAL JOURNAL OF PEPTIDE AND PROTEIN RESEARCH 1982; 19:361-5. [PMID: 6288594 DOI: 10.1111/j.1399-3011.1982.tb02616.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Stimulation of corticosterone and aldosterone production in rat adrenal decapsular and capsular cells respectively by alpha- and beta-melanotropins (alpha- and beta-MSH) have been investigated. Although they are considerably less potent than corticotropin (ACTH), the dose-response curves are parallel to those for ACTH except in the case of aldosterone stimulation by beta-MSH where the dose-response curve is biphasic. The steroidogenic actions of ACTH, beta-MSH and alpha-MSH are antagonized by corticotropin-inhibiting peptide in both capsular and decapsular cells. A synthetic analog of beta-MSH ([Gly10]-betac1-MSH) inhibits both beta-MSH and ACTH in aldosterone output in capsular cells, but it does not inhibit their corticosteroidogenic actions in decapsular cells.
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446
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Cheng CH, Gráf L, Li CH. Human somatotropin 61. A simple method to predict potential of somatotropin fragments for noncovalent recombination by radioreceptor assay. INTERNATIONAL JOURNAL OF PEPTIDE AND PROTEIN RESEARCH 1982; 19:240-2. [PMID: 6288585] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Different mixtures of reduced-alkylated thrombin fragments of human and sheep somatotropin have been tested for binding affinity to liver membranes. The bioassay data correlated well with the abilities of the fragments to form noncovalent recombinants as shown in separate biochemical studies.
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447
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Gráf L, Li CH, Cheng CH, Jibson MD. Two contiguous thrombin fragments of human somatotropin form a functionally active recombinant, but the two homologous fragments from sheep hormone do not. Biochemistry 1981; 20:7251-8. [PMID: 6274394 DOI: 10.1021/bi00528a031] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Two thrombin fragments of reduced-carbamidomethylated human somatotropin representing the full primary structure of the native hormone (residues 1-134 and 135-191) have been found to form a recombinant molecule with properties similar to those of reduced-carbamidomethylated human somatotropin as shown by circular dichroism spectroscopy, two receptor-binding assays, and radioimmunoassay. In contrast, the homologous thrombin fragments of reduced-carbamidomethylated sheep hormone (residues 1-133 and 134-191) do not undergo recombination. Furthermore, neither the reduced-alkylated nor the reduced and nonalkylated C-terminal thrombin fragment of sheep hormone is able to interact with the reduced-carbamidomethylated N-terminal thrombin fragment of human hormone, under conditions which favor the recombination of the two human somatotropin fragments.
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448
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Gràf L, Cheng CH, Li CH. Human somatotropin. Noncovalent interaction of two thrombin fragments restores receptor-binding activity. INTERNATIONAL JOURNAL OF PEPTIDE AND PROTEIN RESEARCH 1981; 18:409-12. [PMID: 6273350 DOI: 10.1111/j.1399-3011.1981.tb02999.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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449
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Cheng CH, Wong TM, Blake J, Li CH. Ovine prolactin. Isoelectricfocusing and characterization of the separated components. INTERNATIONAL JOURNAL OF PEPTIDE AND PROTEIN RESEARCH 1981; 18:343-7. [PMID: 7309380 DOI: 10.1111/j.1399-3011.1981.tb02991.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Highly purified ovine prolactin was subjected to preparative isoelectricfocusing. Although complete separation of the isoelectrically different components was not achieved, four enriched fractions of these components were prepared by this method. Studies on the separated fractions revealed that these components of ovine prolactin, probably a result of deamidation processes, have rather different properties. The more acidic components appeared to be less active in both the radioreceptor assay on mammary gland membranes and the pigeon crop-sac assay. However, the more acidic forms appeared to be more immunoreactive as revealed by radioimmunoassay.
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450
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Li CH, Blake J, Cheng CH, Jibson MD. Human somatotropin: semisynthesis of the hormone by noncovalent interaction of the natural NH2-terminal fragment with a synthetic analog of the COOH-terminal fragment. Arch Biochem Biophys 1981; 211:338-45. [PMID: 6272644 DOI: 10.1016/0003-9861(81)90462-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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