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Biomedical subjects

B N Chiang

Publications and source records attributed to B N Chiang.

At least 73 records · Page 4Linked to original sources
PubMed1991

Impact of demented patients on their family members and care-givers in Taiwan.

A standardized questionnaire was sent to family members or care-givers of 105 patients with dementia; 68 were returned. Eighty-eight percent of the patients were cared for at home by their spouses or adult children. The adverse impacts of dementia on patient family's economy, relations among family members, and social life are recognized. The majority of the subjects had only limited understanding of dementia. Having medical insurance helps the family in caring for the demented patients, emotionally and socially, but not financially. A better social welfare system, as well as health insurance, is recommended.

Adult↗
PubMed1991

Arterial hemodynamics in human hypertension. Effects of adrenergic blockade.

BACKGROUND: Resistance, pulse wave velocity, and wave reflections have been shown to be increased in patients with essential hypertension compared with normotensive controls. These alterations are completely normalized by nitroprusside infusion but exacerbated during beta-adrenergic blockade, suggesting an enhanced smooth muscle tone that is in part modulated by adrenergically mediated vasodilation. The present study was performed to examine the extent to which this apparently enhanced smooth muscle tone is a result of alpha-adrenergically mediated vasoconstriction. METHODS AND RESULTS: Age-matched normotensive and hypertensive Chinese subjects were instrumented with catheter-tipped micromanometers and an electromagnetic flow velocity sensor positioned in the ascending aorta. Aortic impedance and wave reflection properties were obtained from Fourier analysis of the pressure and flow signals during baseline conditions, after beta-blockade with propranolol (0.15 mg/kg i.v.), and after alpha-blockade with intravenous phentolamine (range, 15-80 mg) that was sufficient to either normalize blood pressure or produce a pressure that could not be further lowered. Compared with normotensives, in the baseline state, hypertensives had elevated resistance (1,962 versus 1,268 dyne.sec/cm5, p less than 0.001), total power (1,893 versus 1,568 mW, p less than 0.08), reflected pressure wave component (25.6 versus 13.5 mm Hg, p less than 0.001), ratio of reflected to forward wave (0.65 versus 0.42, p less than 0.001), and pulse wave velocity as determined from the frequency of the first zero-crossing of impedance phase angle (4.6 versus 3.5 Hz, p less than 0.03). During combined alpha- and beta-adrenergic blockade, blood pressure decreased into the normal range (from 162/103 to 131/87 mm Hg) but was still somewhat higher than that in the normotensive subjects. Resistance (1,914 dyne.sec/cm5, p less than 0.03), reflected wave (19.5 mm Hg, p less than 0.01), and ratio of reflected to forward wave (0.61, p less than 0.001) were, however, persistently elevated above normal values. CONCLUSIONS: alpha-Adrenergically mediated vasoconstriction cannot account for all of the hemodynamic alterations seen in essential hypertension.

Adult↗
PubMed1991

Immunoregulatory effects of phospholipase A2 (PLA2) on the proliferation of human lymphocytes.

Extracellular phospholipase A2 (PLA2) is a proinflammatory enzyme found especially in the inflammatory exudate to modulate blood flow to areas of antigen stimulation. In this study we found that PLA2 exerted a biphasic effect on the proliferation of phytohemagglutinin (PHA)-stimulated human mononuclear cells (PHA MNC). At low concentrations range from 0.001 to 1 U/ml, PLA2 enhanced the proliferation of PHA MNC (maximal increase was 37.0 +/- 5.67%). Conversely, at concentrations over 10 U/ml, PLA2 markedly suppressed the PHA-induced MNC proliferation (maximal decrease was 88.86 +/- 2.89%). PLA2 was non-toxic to lymphocytes after three days culture, unless the concentration was higher than 100 U/ml. The membrane polarization of PHA-stimulated lymphocytes was also increased by PLA2 at a low concentration. In addition, PLA2 displayed a similar effect on the proliferation of streptokinase-streptodornase (SK/SD) or allogeneic cell stimulated lymphocytes. The change of lymphocyte proliferation by PLA2, was parallel to the change of percentage of helper T cells. Furthermore--a CD4-rich population was proved more susceptible to PLA2 effect than a CD8-rich population. Para-bromophenacyl bromide (pBPB), an irreversible inhibitor of PLA2, abrogated the biphasic effect of PLA2 on PHA MNC proliferation. These results suggest that PLA2 plays a regulatory role on immune reactions by modulating the percentage of helper T cells.

Deoxyribonucleases↗
PubMed1991

Aldosterone-producing adenoma--variable serum aldosterone response to postural change: a case report.

A 25-year-old female was admitted for evaluation of hypertension and hypokalemia. Plasma renin activity was suppressed and plasma aldosterone level was higher than normal. The CT scan of adrenal gland revealed a 2.5cm in size low density tumor mass over right adrenal area, and NP-59 adrenal scan showed early and persistent uptake of radioactivity in the right adrenal gland. Interestingly, the plasma aldosterone level was elevated, decreased and unchanged to postural change on three different occasions. After right adrenalectomy, the plasma aldosterone level decreased to 4.77ng/dl, blood pressure, serum potassium, and plasma aldosterone returned to normal response to postural change. Histologically, it was compatible with the picture of cortical adenoma. However, the tumor cell may not have reached autonomous function yet, since different responses of plasma aldosterone to postural change were observed clinically.

Adenoma↗
PubMed1991

Defective expression of neutrophil C3b receptors and impaired lymphocyte Na(+)-K(+)-ATPase activity in patients with systemic lupus erythematosus.

In our previous report, we demonstrated that the functions of phagocytes and lymphocytes were defective in patients with systemic lupus erythematosus (SLE). In an attempt to further clarify the defective mechanisms of these cells, 25 active SLE, 10 bronchial asthma patients (BA) on corticosteroids and 25 age and sex-matched normal individuals were investigated for the expression of membraneous C3b receptors, ionophore-induced 45Ca(2+)-uptake, mitochondrial potentials and phagocytic activity of neutrophils. We found decreased expression of C3b receptors on SLE PMN in both resting (37.2 +/- 3.7% of the normal controls) and FMLP-stimulated (68.3 +/- 7.1% of the normal controls) conditions, whereas the C3b receptor expression on BA-PMN receiving long-term steroid treatment was not different from normal controls. This suggests that the defective phagocytosis of SLE PMN is in the recognition, but not in the ingestion phase because of the normal function of Ca(2+)-influx and mitochondrial activity in SLE PMN. On the other hand, hyporesponsiveness to PHA stimulation (stimulation index: 127.4 +/- 46.3 in SLE vs. 311.2 +/- 30.4 in normals, p = 0.0077) was a distinct cell-mediated immune abnormality in our SLE patients. We measured the membrane potential of individual cells using 3,3'-dihexyloxacarbocyanin and found hyperpolarization in resting SLE lymphocytes. However, the membrane polarization of SLE lymphocytes became lower than that of normal cells after PHA stimulation for 3 days. A similar tendency was also found in Na(+)-K(+)-dependent ATPase activity in SLE lymphocytes.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1991

Enalapril in congestive heart failure: acute hemodynamic and neurohumoral evaluation and short-term follow-up.

The acute efficacy of rapid loading of oral long-acting enalapril in congestive heart failure remains to be established. We evaluated the efficacy of this treatment modality in 22 patients with chronic congestive heart failure N.Y.H.A. functional class ranging from II-IV with Creatinine level less than 2 mg/dl. Following hemodynamic evaluation, there was significant favorable change in the left ventricular functional curve. Moreover, acute hemodynamic assessment showed a significant reduction in pulmonary capillary wedge pressure from 19.2 +/- 4.8 to 17.2 +/- 4.7 mmHg (p less than 0.005) and an increases in stroke volume index from 28.3 +/- 9.2 to 33.1 +/- 7.5 ml/m (p less than 0.005). After rapid enalaprilization, blood pressure fell from 127 +/- 21/78 +/- 15 to 108 +/- 21/68 +/- 15 mmHg (p less than 0.005), systemic vascular resistance from 1725 +/- 602 to 1370 +/- 376 dyne.sec.cm-5 (p less than 0.05) and pulmonary vascular resistance from 262 +/- 19 to 218 +/- 65 dyne.sec.cm-5 (p less than 0.05). Cardiac index rose significantly from 2.43 +/- 0.62 to 2.60 +/- 0.50 l/min/m2 (p less than 0.05). In terms of neurohumoral assessments, there was a significant inhibition of the renin-angiotensin-aldosterone system. Aldosterone fell from 21.3 +/- 13.4 to 9.4 +/- 8.0 ng/dl and plasma renin activity rose from 3.3 +/- 4.6 to 11.3 +/- 11.0 ng/nl/hr (p less than 0.005). Plasma norepinephrine and epinephrine levels were found to have significant reduction in addition to antidiuretic hormone concentration. During short-term trial, left ventricular ejection fraction was significantly elevated from 27.5 +/- 6% to 32.8 +/- 10.8% (p less than 0.005). Thus, this limited study clearly demonstrates the rapid administration of enalapril not only achieves inhibition of renin-angiotensin-aldosterone system but also reduces preload and afterload significantly in the failing heart. We conclude that rapid enalaprilization is an effective methodology which still needs meticulous attention, providing significant hemodynamic and symptomatic benefits in patients with chronic congestive heart failure.

Aged↗
PubMed1991

Comparison of enalapril and conventional vasodilator therapy in patients with chronic congestive heart failure.

The aim of this study was to investigate the role of the renin-angiotensin-aldosterone system during anti-heart failure treatment with additional enalapril versus conventional vasodilator therapy (hydralazine + sorbitrate) and to assess whether or not enalapril can be suggested as the preferential vasodilator therapy in patients with chronic congestive heart failure. Over a 2.5-year period, 120 patients (New York Heart Association II-IV, creatinine less than or equal to 2.0 mg/dl) were enrolled in the study and randomly assigned to receive enalapril or hydralazine and sorbitrate therapy in addition to optimal digitalis and diuretics administration. At the end of a one-year followup, there was a tendency for mortality to be lower in the enalapril[correction of enlapril] group (4 cases) compared to the conventional group (9 cases), but the difference was not significant (p = 0.21). Both groups showed similar increases in plasma renin activity. The plasma aldosterone level decreased significantly in the enalapril group (p less than 0.005); whereas it rose significantly in the conventional group (p less than 0.005). The plasma norepinephrine level of the enalapril group fell significantly when compared with the conventional group. Thus, enalapril therapy achieved better reduction in the activating sympathetic system (p less than 0.0001). Reduction in the anti-diuretic hormone level was also found to be highly significant in the enalapril group, whereas no difference was seen in the conventional group. Furthermore, the serum creatinine level and blood urea nitrogen remained unchanged in the conventional group; whereas both were demonstrated to be reduced significantly in the enalapril group at a 1-year follow up.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1990

Detection of prosthetic mitral valve leak: a comparative study using transesophageal echocardiography, transthoracic echocardiography, and auscultation.

Paravalvular leakage is a major complication of prosthetic valve dysfunction. Sixty-one subjects with valvular heart disease who had received prosthetic mitral valve replacement 5 months to 5 years before (43 received a porcine prosthesis and 18 received Bjork-Shiley valve prostheses) were evaluated for this complication. Careful auscultation was performed by two experienced cardiologists followed by transthoracic and transesophageal echocardiography. Physiologic leaks were detected in all Bjork-Shiley valves, but in only 30% of porcine valves using transesophageal echocardiography. These regurgitant jets were flame-like, with mean low velocities of 50 +/- 12.3 cm/sec and 48 +/- 18.2 cm/sec in the two types of valves. Neither transthoracic echocardiography nor auscultation could detect physiological regurgitant jets. Ten cases with paravalvular leak were detected by transesophageal echocardiography and subsequently demonstrated by left ventriculography (7 porcine, 3 Bjork-Shiley valves). Pathologic regurgitant jets were seen as high-velocity, systolic-retrograde turbulent flow across the prosthesis. However, only 6 cases of prosthetic valve dysfunction were detected by transthoracic echocardiography, 4 cases of mild paravalvular leakage went undetected. Thirteen of the 61 subjects had an apical systolic murmur and suspected prosthetic valve leakage; in 10 of the 13 cases the findings corresponded to those obtained by transesophageal echocardiography. In 3 cases of double valve replacement with Bjork-Shiley valves the magnitude of the leakage was overestimated by auscultation.

Adult↗
PubMed1990

Late effects in mouse heart after 60Co gamma-irradiation of the brain: an ultrastructural study.

A single dose of 8 or 20 Gy 60Co gamma-rays was given to C3H male mice at 4 months of age. Degenerative changes in the cardiac muscle due to brain irradiation were observed first at 6 months after irradiation, and became progressively more severe at 12-24 months. The changes seen at the ultrastructural level included myofibrillolysis, the presence of lysosomal-like bodies and interstitial fibrosis. Ultrastructural changes in the control cardiac muscle throughout the experimental period were monitored and only minor aging changes were noted. The coronary arteries of control mice began to show a slight amount of smooth muscle degeneration and fibrosis 1 year into the experiment. At 18 months the lesions became more severe, and at 24 months there was relatively less distinction between the control and the 20 Gy treated group. Degenerative changes in the coronary arteries were noticed at 6 months after irradiation, and became progressively more severe at later times (12-24 months). The major changes included smooth muscle degeneration with fibrosis and the accumulation of debris and extracellular matrix. At 18 months the medial smooth muscle showed severe damage, with accumulations of matrix material and debris. There was additional fibrosis in the adventitial layer. There were few additional changes at 24 months after 20 Gy irradiation. Quantitative analyses indicated that the average fractional volumes of degenerated smooth muscle cells were 13, 27 and 39% in the unirradiated group at 12, 18 and 24 months, respectively, and 13 and 29% in the sham-irradiated group at 12 and 18 months into the experiment, respectively. These percentages were 12, 32 and 49% (P less than 0.05) after 8 Gy irradiation, and 19% (P less than 0.05), 46% (P less than 0.01), and 42% after 20 Gy irradiation, respectively.

Animals↗
PubMed1990

Regional pulse wave velocities in hypertensive and normotensive humans.

STUDY OBJECTIVE: The aim was to compare regional wave transmission and reflection properties along the aorta in age matched normotensive and hypertensive subjects. DESIGN: Simultaneous upstream and downstream micromanometer pressures were recorded at five regions from the ascending aorta to the iliac artery. Recordings were made in the baseline condition in both groups and during sustained isometric handgrip exercise in the normotensives to see if increasing the blood pressure to hypertensive levels would eliminate baseline differences between the two groups. SUBJECTS: Only subjects who had no coronary or valvular heart disease were studied. Normotensive subjects (n = 8) were selected from those undergoing electrophysiological testing whose blood pressures were consistently in the normal range (systolic less than 140, diastolic less than 90 mm Hg). Age matched hypertensive subjects (n = 17) were those in whom secondary causes of hypertension were excluded and who had repeated measurements of raised blood pressure. MEASUREMENTS AND RESULTS: In each region pulse wave velocity was estimated from the simultaneous upstream and downstream pressure records using the foot to foot method, and apparent phase velocity was obtained from Fourier analysis of the two pressures. The intensity of wave reflections was judged by the magnitude of fluctuations of the harmonics of apparent phase velocity about the mean of the higher frequency harmonics. In both groups in the baseline state there were regional variations in the pulse wave velocity with the lowest values occurring just proximal to the renal arteries and highest values occurring in the iliac artery. Likewise, in both groups the extent of wave reflections varied regionally--pronounced reflections were seen in the ascending aorta and from just proximal to the renal arteries to the aortic bifurcation but not in the mid-thoracic or iliac regions. The hypertensives had higher pulse wave velocity than normotensives only in the iliac artery (780 v 567 cm.s-1) and had more reflections in the three regions in which reflections were evident. Although handgrip in the normotensive group eliminated regional differences in pulse wave velocity between the groups, reflections were still greater in the hypertensives. CONCLUSIONS: Essential hypertension affects the regional properties of the aortic wall. These alterations are manifested by increased peripheral wave-speed and increased wave reflections along the aorta. The differences in wavespeed but not reflection properties are eliminated when the pressures are matched by handgrip, suggesting that factors other than the level of blood pressure per se are responsible for the alterations in reflection properties.

Adult↗
PubMed1990

Characterization of murine liver-derived inhibitory protein.

Murine liver-derived inhibitory protein (LIP) capable of inhibiting human lymphocyte proliferation was highly purified from liver extract. Its molecular weight determined by gel filtration and SDS-PAGE was 105,000 and 38,400 respectively. LIP moved electrophoretically at the gamma-globulin region. Its activity in inhibiting lymphocyte proliferation was temperature-stable up to 60 degrees C, and pH-stable between 4 and 11. It was not cytotoxic to lymphocytes as shown in 51Cr-release experiments. The purified LIP possessed arginase activity.

Animals↗
PubMed1990

Usefulness of echocardiography in the prediction of early results of catheter balloon mitral valvuloplasty.

Catheter balloon mitral valvuloplasty (BMV) was performed in 50 patients and 32 of them undergoing BMV with double balloon technique were studied to evaluate the usefulness of echocardiography in the prediction of early results of BMV. Five echocardiographic variables including mitral valve motion, mitral valve thickness, subvalvular change, commissural calcification and left atrial dimension were evaluated. Each variable was divided into mild, moderate and severe subgroups. Before valvuloplasty there were no differences in mitral valve area among any subgroup for any variable. After valvuloplasty, variables associated with a greater increase in mitral valve area from mild and moderate subgroups than from severe subgroup included mitral valve motion, mitral valve thickness, and subvalvular change, but not commissural calcification or left atrial dimension. We scored the former 3 variables as 0, 1 and 2 points in the mild, moderate and severe subgroups, respectively. The sums of individual scores in these 3 variables were further divided into 3 groups: 12 patients had a lower score (less than 2), 10 patients had a score of 3-4 and 10 patients had a higher score (greater than 5). Patients with lower scores tended to have greater increases in mitral valve areas after valvuloplasty than those with higher scores. Thus, mitral valve motion, mitral valve thickness and subvalvular change may be useful to predict a greater increase in mitral valve area after valvuloplasty. A lower score of echocardiographic variables anticipates successful balloon mitral valvuloplasty, which may be helpful in patient selection.

Adult↗
PubMed1990

Aortic and pulmonary input impedance in patients with cor pulmonale.

The hydraulic load of the right and left ventricles and the clinical effects of nifedipine were evaluated in 8 normal subjects (mean age: 55 years) and 8 patients with cor pulmonale secondary to chronic obstructive lung disease (mean age: 57 years). It was found that there were differences in the right ventricular resistance (174.62 +/- 25.96 vs 468.57 +/- 178.81 dyne/sec/cm-5), first zero crossing frequency (3.62 +/- 0.34 vs 6.07 +/- 3.56 Hz), steady power (218.95 +/- 32.25 vs 359.44 +/- 37.46 mW) and total power of right ventricle (275.81 +/- 36.18 vs 440.46 +/- 85.16 mW) between the normal and cor pulmonale patients, respectively. However, no significant changes in characteristic impedance, pulsatile power or aortic impedance were observed in the right pulmonary artery. After administration of nifedipine to patients with cor pulmonale, there were significant changes in resistance (468.57 +/- 178.81 vs 256.36 +/- 178.56 dyne/sec/cm-5), steady power (359.44 +/- 37.46 vs 225.51 +/- 114.64) and total power (440.46 +/- 85.16 vs. 289.27 +/- 50.85) of the pulmonary artery, respectively. Otherwise there were no significant changes in aortic input impedance or characteristic impedance of right pulmonary artery and pulsatile power. In conclusion, we found that: 1) the hydraulic vascular load in the right ventricle was higher in patients with cor pulmonale, 2) characteristic impedance that was not increased in cor pulmonale patients may be due to a dilated pulmonary artery, 3) there was no impedance mismatch between left ventricle and systemic arterial system in patients with cor pulmonale, and 4) by reducing the pulmonary vascular resistance through nifedipine administration, the total external right ventricular power might be reduced, without affecting the proximal pulmonary arterial compliance.

Aorta↗
PubMed1990

Contributing factors to formation of left atrial spontaneous echo contrast in mitral valvular disease.

The formation of left atrial spontaneous echo contrast may relate to blood stasis. This study analyzed the factors contributing to the formation of that contrast. Transesophageal echocardiography, transthoracic echocardiography, cardiac catheterization, and left ventricular angiography were performed in 139 patients, divided into five groups. Predominant mitral stenosis with atrial fibrillation was found in 36 patients (group I); normal porcine valve in the mitral valvular area with atrial fibrillation in 31 (group II); predominant mitral stenosis with normal sinus rhythm in 26 (group III); moderate to severe mitral regurgitation with atrial fibrillation in 25 (group IV); atrial fibrillation with normal mitral valve in 21 (group V). The results showed left atrial spontaneous contrast echo was found in only 1 of 139 patients by transthoracic echocardiography and 62 of 139 cases were detected by transesophageal echocardiography. There was a high incidence of left atrial spontaneous echo contrast in cases of mitral obstruction with atrial fibrillation and enlarged left atrium (group I, 88%; group II, 74%), but a lower incidence in cases with normal sinus rhythm (group III, 4%), atrial fibrillation alone (group V, 16%), and increased left atrial flow velocity (group IV, 9.5%). The diameter of the left atrium was significantly different between presence and absence of left atrial spontaneous contrast echo (54.3 +/- 9.2 mm vs. 48.3 +/- 8.6 mm, p less than 0.01). The mean pressure gradient was similar in groups I and III (14.6 +/- 0.6 mHg and 14.4 +/- 2.8 mHg, respectively) but different in group II (10.9 +/- 3.2 mHg, p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Evidence that an immunosuppressive protein from murine liver is arginase.

A protein (mLIP) with strong inhibitory activity on PHA-induced lymphocyte proliferation was purified to homogeneity from murine liver. Both the arginase activity and the inhibitory activity were found superimposed on the same peak during gel filtration. The arginase activity of mLIP was identified by determining the arginine degradation products, urea (by alpha-diketone-urea complex formation) and ornithine (by HPLC). The inhibitory activity of mLIP was neutralized by adding more arginine to the culture medium. The mutual action between mLIP and arginine was found to be dose-related. Furthermore, the inhibition and arginase activities were simultaneously absorbed by anti-mLIP affinity column and both reappeared in the acid-eluate. These results indicate that the murine liver-derived inhibitory protein is the liver L-arginase itself.

Animals↗
PubMed1990

Clonidine suppresses digitalis-induced ventricular tachycardia in cats.

Effects of intravenous (IV) and intravertebral arterial (IA) administrations of alpha-2 adrenoceptor agonist, clonidine (CLO) and its antagonist, yohimbine (YOH, 0.05 mg/kg, IA), on the ventricular tachycardia (VT) induced with IV acetyl strophanthidin (AS) were studied in cats anesthetized with intraperitoneal chloralose. IVAS does-dependently produced cardiac arrhythmias including complete atrioventricular conduction block (118 +/- 14 micrograms/kg), junctional tachycardia (128 +/- 20 micrograms/kg), multiform ventricular premature beats (157 +/- 21 micrograms/kg) and sustained VT (220 +/- 23 micrograms/kg). IACLO dose for terminating VT induced with IVAS was about one fifth of IVCLO dose. IACLO dose for terminating VT induced with IVAS + IVYOH was significantly higher than that in VT induced with IVAS (14.8 +/- 3.7 vs 5.8 +/- 1.0 micrograms/kg, p less than 0.005). These experiments clearly demonstrated that IAYOH specifically antagonized the antiarrhythmic effect of IA CLO on the AS-induced VT. Since small dose of IA administration of the drugs acts mainly on the central nervous system, we suggest that the antiarrhythmic effect of CLO on AS-induced VT is likely through the central alpha-2 adrenoceptor.

Animals↗
PubMed1990

Silent corticotropic adenoma of pituitary gland--a case report.

A 79-year-old man complained progressive visual impairment and Diplopia for 2 weeks. A big pituitary tumor was found and partially removed by the surgeon eventually. The tumor cells were chromophobic with H&E stain and exhibited focal positive staining with PAS. Immunoperoxidase method demonstrated moderate positivity for adrenocorticotrophic hormone (ACTH), while staining for growth hormone (G.H) and prolactin were negative. The patient was eucorticoid clinically and biochemically. Since silent corticotropic adenoma of the human pituitary gland is rarely encountered clinically, a review of the literature is included in this article.

Adenoma, Chromophobe↗