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Biomedical subjects

C I Chang

Publications and source records attributed to C I Chang.

At least 19 recordsLinked to original sources
PubMed2001

Balloon angioplasty for obstructed modified systemic-pulmonary artery shunts and pulmonary artery stenoses.

OBJECTIVES: The results of percutaneous balloon angioplasty for obstructed modified Blalock-Taussig (BT) or central shunts and pulmonary artery (PA) stenoses were studied to assess its role as an alternative to second shunt and surgical PA angioplasty. BACKGROUND: Obstruction of a modified shunt and PA stenosis related to the shunt or ductus are not infrequent. A second shunt with or without PA angioplastv is required if the PA size, morphology or age of the patient is suboptimal for definitive surgery. METHODS: From June 1994 to May 1999, balloon angioplasty for obstructed systemic-to-PA shunts was performed in 46 patients, with ages ranging from 1 month to 7.4 years (2.2 +/- 1.9 years). Among the 46 patients, 32 had modified BT shunts, 5 had bilateral shunts, 7 had modified central shunts, and 2 had both modified BT and central shunts. Stenoses were seen in 27 main branch PAs, and interruption was present in three. A concurrent balloon angioplasty was attempted in 28 main branch PAs, but it was performed in only 25 vessels. RESULTS: Balloon dilation for obstructed modified shunts was considered to be effective in 42 patients (91%), while angioplasty for PA stenosis was effective in 14 vessels and not effective in 11 vessels. After balloon dilation angioplastv, oxygen saturation in the aorta increased from 74.4 +/- 4.3% to 80.8 +/- 3.6% (p < 0.01) in these 46 patients. One patient died of pneumonia. Eight patients required an additional modified BT shunt soon after the procedure because of severe stenosis or interruption at main branch PA. After a mean follow-up period of 11.6 +/- 5.4 months, 29 patients underwent a repeated imaging study to evaluate the morphology and size of the PAs. Of these 29 patients, 26 underwent open-heart surgery, with two mortalities. CONCLUSIONS: When a second shunt is under consideration because of obstruction of the modified shunt, balloon angioplasty is a possible alternative procedure. Pulmonary artery stenosis, if present, can be simultaneously dilated.

Angioplasty, Balloon↗
PubMed2001

Macrophage arginase promotes tumor cell growth and suppresses nitric oxide-mediated tumor cytotoxicity.

Macrophages use L-arginine to synthesize nitric oxide (NO) and polyamines through the inducible NO synthase (iNOS) and arginase, respectively. The released NO contributes to the tumoricidal activity of macrophages, whereas polyamines may promote the growth of tumor cells. Both the tumoricidal and growth-promoting activities from macrophages have been reported; however, the underlying mechanisms for switching between this dual function of macrophages remain unclear. Here, we test the hypothesis that arginase participates in the switching between the cytotoxic and growth-promoting activities of macrophages toward tumor cells. To alter arginase activity in macrophages, cells (murine macrophage cell line J774A.1) were transfected with the rat liver arginase gene or treated with an arginase inhibitor, L-norvaline. The effects of macrophage arginase activity on the growth-promoting and cytotoxic activities of macrophages toward breast tumor cells (ZR-75-1) were investigated in a coculture system. The results demonstrated that overexpression of arginase in macrophages enhanced L-ornithine and putrescine production and consequently promoted tumor cell proliferation. This proliferative effect was down-regulated by the arginase inhibitor L-norvaline. Furthermore, increases in arginase activity also attenuated NO production by the lipopolysaccharide-activated macrophages and thus reduced the cytotoxic effect on cocultured tumor cells. Inhibiting arginase activity by L-norvaline effectively reversed the suppression of NO-mediated tumor cytotoxicity. Together, these results suggest that arginase induction in macrophages can enhance tumor cell growth by providing them with polyamines and suppress tumor cytotoxicity by reducing NO production. It appears that L-arginine metabolism through the arginase and iNOS pathways in macrophages can have very different influences on the growth of nearby tumor cells depending on which pathway is prevailing.

Adenocarcinoma↗
PubMed2001

The assessment of the proximal left pulmonary artery by transesophageal echocardiography and computed tomography in neonates and infants: a case series.

IMPLICATIONS: Transesophageal echocardiography (TEE) is often used during surgical repair of congenital heart disease. In our case series of 256 newborns and infants, we found that a left paracarinal view of TEE could visualize the proximal left pulmonary artery, a frequent blind spot for TEE, in most patients, except in a few cases with anatomic variations of the esophagus in the right lateral to the vertebra.

Cardiac Surgical Procedures↗
PubMed2001

Preoperative diagnosis by electron beam computed tomography and perioperative management of primary tracheal anomalies in tetralogy of Fallot.

PURPOSE: To investigate the usefulness of electron beam computed tomography (EBCT) in the preoperative detection and perioperative management of insidious concomitant primary tracheobronchial anomalies in patients with tetralogy of Fallot (TF). METHODS: From July 1995 to October 1999, 88 children (38 girls, 50 boys) with TF were enrolled in this study. EBCT examinations provided information needed to plan management. The final diagnoses of airway abnormalities were correlated with the findings of bronchoscopy in five patients and confirmed during surgery. RESULTS: Fourteen (16%) of the 88 patients had associated primary tracheobronchial anomalies. Nine patients had tracheal bronchi, which were combined with tracheobronchial stenosis in two patients and with tracheal stenosis in one patient. Two patients had tracheal diverticulum, which was combined with lower tracheal stenosis in one patient. Two patients had congenital tracheal stenosis. Tracheomalasia was found in one patient. Three patients with ventilation difficulties died postoperatively. Special attention was given to the care of the diseased airways perioperatively, and the remaining 11 patients had a smooth course of hospitalization and discharge. CONCLUSIONS: Our results show that EBCT provides good delineation of both cardiac and tracheobronchial anomalies and suggest that it should be used perioperatively to detect associated airway anomalies in TF, to facilitate the design of an appropriate ventilation care strategy.

Adolescent↗
PubMed2000

Use of prawn blood agar hemolysis to screen for bacteria pathogenic to cultured tiger prawns Penaeus monodon.

A newly developed prawn blood agar consisting of 1 ml of tiger prawn hemolymph in medium containing 200 ppm Rose Bengal was used to determine the hemolytic activity of 35 isolates of bacteria obtained from cultured tiger prawns Penaeus monodon and their rearing water. For comparison, the hemolytic activity of these isolates was also determined in sheep blood agar. Nine isolates (25.7% of total) showed different hemolytic reactions on prawn blood agar and sheep blood agar. From the 35 isolates, 8 with various hemolytic characteristics were selected and the relationship between the type of hemolytic activity and pathogenicity was determined and compared. Four isolates that showed hemolytic activity in prawn blood agar caused high mortality to cultured tiger prawns. By contrast, a significantly lower mortality rate was observed for tiger prawns injected with 4 isolates that did not exhibit hemolytic activity on prawn blood agar. Results further showed that mortality did not correlate with hemolytic activity determined using sheep blood agar. Prawn blood agar containing P. monodon hemocytes was faster and more accurate for determining prawn hemolytic activity of bacterial isolates.

Agar↗
PubMed2000

The involvement of tyrosine kinases, cyclic AMP/protein kinase A, and p38 mitogen-activated protein kinase in IL-13-mediated arginase I induction in macrophages: its implications in IL-13-inhibited nitric oxide production.

In macrophages, L-arginine can be used by NO synthase and arginase to form NO and urea, respectively. Therefore, activation of arginase may be an effective mechanism for regulating NO production in macrophages through substrate competition. Here, we examined whether IL-13 up-regulates arginase and thus reduces NO production from LPS-activated macrophages. The signaling molecules involved in IL-13-induced arginase activation were also determined. Results showed that IL-13 increased arginase activity through de novo synthesis of the arginase I mRNA and protein. The activation of arginase was preceded by a transient increase in intracellular cAMP, tyrosine kinase phosphorylation, and p38 mitogen-activated protein kinase (MAPK) activation. Exogenous cAMP also increased arginase activity and enhanced the effect of IL-13 on arginase induction. The induction of arginase was abolished by a protein kinase A (PKA) inhibitor, KT5720, and was down-regulated by tyrosine kinase inhibitors and a p38 MAPK inhibitor, SB203580. However, inhibition of p38 MAPK had no effect on either the IL-13-increased intracellular cAMP or the exogenous cAMP-induced arginase activation, suggesting that p38 MAPK signaling is parallel to the cAMP/PKA pathway. Furthermore, the induction of arginase was insensitive to the protein kinase C and p44/p42 MAPK kinase inhibitors. Finally, IL-13 significantly inhibited NO production from LPS-activated macrophages, and this effect was reversed by an arginase inhibitor, L-norvaline. Together, these data demonstrate for the first time that IL-13 down-regulates NO production through arginase induction via cAMP/PKA, tyrosine kinase, and p38 MAPK signalings and underline the importance of arginase in the immunosuppressive activity of IL-13 in activated macrophages.

Animals↗
PubMed2000

Podocarpane-type trinorditerpenes from the bark of Taiwania cryptomerioides.

Five new podocarpane-type trinorditerpenes were isolated from the bark of Taiwania cryptomerioides. Structures of 1beta, 14-dihydroxy-13-methoxy-6,8,11,13-podocarpatetraene (1), 1beta, 14-dihydroxy-13-methoxy-8,11,13-podocarpatriene (2), 13-hydroxy-12-methoxy-8,11,13-podocarpatrien-3-one (3), 14-hydroxy-13-methoxy-1,8,11,13-podocarpatetraen-3-one (4), and 13-methoxy-8,12-podocarpatriene-11,14-dione (5) were determined by NMR, MS, and other spectral and chemical evidence.

Diterpenes↗
PubMed2000

Quantitative study of mucosal wave via videokymography in canine larynges.

OBJECTIVES: Vocal fold mucosal wave movements are thought to be important in determining voice characteristics and quality. To see these movements, high-speed cinematography and videostroboscopy have been used clinically; however, these techniques have disadvantages that make them impractical for quantitative measurement of mucosal wave movements. This study explored the feasibility of using line-scan cameras for mucosal wave analysis. METHODS: An excised larynx bench model was used to examine the effects of elongation and changes in subglottal pressure on the amplitude, frequency, and phase difference of vocal fold mucosal movements as calculated from line-scan images. RESULTS: The data showed a positive and linear relationship between an increase in subglottal pressure and amplitude of the mucosal wave; elongation of the vocal folds appeared to decrease the amplitude of mucosal wave upheaval at each level of subglottal pressure. Similarly, increase in subglottal pressure had a positive and linear relationship with increase in frequency of vibration; elongation of the vocal folds further increased the frequency at any given subglottal pressure. Phase difference between the movements of the upper and lower margins of the mucosal lips was estimated and did not appear to be significantly affected by changes in subglottal pressure and elongation. CONCLUSION: The data presented in this study are consistent with relationships that we would expect to be true from currently accepted models of vocal fold vibration.

Animals↗
PubMed2000

Six new compounds from the heartwood of Diospyros maritima.

Six new compounds, diospyrolide (1), diospyrolidone (2), diethyl (2R)-malate (3), 3-(E)-coumaroylbetulin-28-yl ethyl nonanedioate (4), 3-(E)-coumaroylbetulin-28-yl ethyl succinate (5), and 3-(E)-coumaroylbetulin-28-yl ethyl (2R)-2-hydroxysuccinate (6), have been isolated from the heartwood of Diospyros maritima. Compounds 1 and 2 are novel trinorlupanes, and 4, 5 and 6 are lupane derivatives. Their structures were determined using spectral and chemical methods.

Magnetic Resonance Spectroscopy↗
PubMed2000

Six podocarpane-type trinorditerpenes from the bark of Taiwania cryptomerioides.

Six podocarpane-type trinorditerpenes were isolated from the bark of Taiwania cryptomerioides. Their structures, 14-hydroxy-13-methoxy-8,11,13-podocarpatrien-7-one (1), 13-hydroxy-12-methoxy-8,11,13-podocarpatriene (2), 12-hydroxy-13-methoxy-8,11,13-podocarpatriene (3), 14-hydroxy-13-methoxy-8,11,13-podocarpatriene (4), 13-hydroxy-8,11,13-podocarpatriene (5), and 13,14-dihydroxy-8,11,13-podocarpatrien-7-one (6), were determined principally from spectral evidence.

Diterpenes↗
PubMed2000

Fibrinofibrous pericarditis mimicking a pericardial tumor.

Primary pericardial disease is rare in children. The clinical features usually reflect limited venous return and cardiac output. Tuberculous pericarditis is the leading cause of pericardial disease in developing nations. A definitive diagnosis in children is frequently difficult and the manifestations are protean. We report a 10-month-old girl with fibrinofibrous pericarditis that manifested as constrictive pericarditis with prolonged fever, hepatomegaly, edema, and poor appetite. Echocardiography showed a solid mass that originated from the thickened pericardium and compressed the whole heart. In contrast, computed tomography revealed pericardial thickening with fluid collection. The symptoms and signs dramatically improved after surgical pericardiectomy. Pathologic analysis confirmed the diagnosis of tuberculous fibrinofibrous pericarditis. The patient received a 1-year course of antituberculosis therapy and has remained symptom free for 2 years. We suggest that a discrepancy between echocardiography and computed tomography (CT) findings might indicate a diagnosis of fibrinofibrous pericarditis.

Diagnosis, Differential↗
PubMed2000

Use of extracorporeal membrane oxygenation to rescue a child with acute respiratory distress syndrome.

Acute respiratory distress syndrome (ARDS) carries a high mortality of about 60%. The results of conventional treatments for ARDS are poor. We report the use of extracorporeal membrane oxygenation (ECMO) to rescue a child with ARDS. The patient, a 7-year-old boy, underwent a Ross procedure and mitral valvuloplasty because of severe aortic and mild mitral regurgitation. ARDS due to massive transfusion and prolonged cardiopulmonary bypass developed in the early postoperative period. Hypoxemia persisted despite conventional treatments, including pressure-controlled ventilation and high-frequency ventilation. Finally, venovenous ECMO was used to rescue the patient. With ECMO support, gas exchange was well maintained with a lower ventilator setting, and ventilator-induced lung injuries were avoided. ECMO was used for 183 hours, at which point the boy was weaned without complications. His recovery was uneventful. At the latest follow-up, 6 months after the operation, he was in New York Heart Association function class I and had no complaints of lung disease. This case suggests that venovenous ECMO can be a rescue method for patients with ARDS that is refractory to conventional treatments.

Child↗
PubMed1999

Outcomes of transcatheter valvotomy in patients with pulmonary atresia and intact ventricular septum.

The results of transcatheter valvotomy in pulmonary atresia with intact ventricular septum (PA-IVS) patients are presented with an attempt to identify the predictive factors for pulmonary valvotomy alone as definitive treatment. Between June 1995 and December 1997, 14 PA-IVS neonates with tripartite right ventricle underwent an attempted pulmonary valvotomy. For perforation of the pulmonary valve, a guidewire was used in 4, and a radiofrequency guidewire in 10 patients. Two outcome groups were identified. Group I included those in whom transcatheter treatment achieved a definitive success; group II patients required surgery despite an initial successful valvotomy. The attempt failed in 3 patients, 1 of whom had pericardial effusion. Perforation of the pulmonary valve was achieved in 11 patients: 2 with a guidewire and 9 with a radiofrequency guidewire. A subsequent balloon valvuloplasty was performed in these 11 patients. After valvuloplasty, mean right ventricular pressure decreased from 124 +/- 24 to 60 +/- 15 mm Hg (p <0.01). One died of heart failure and infection 10 days later, despite successful weaning from prostaglandin E1. Group I patients (n = 6) were treated with transcatheter valvotomy alone. Group II patients (n = 4) required right ventricular outflow patch. Significant differences between the 2 groups (group I vs II) were identified in tricuspid valve Z value (0.52 +/- 0.37 vs -1.25 +/- 0.48, p <0.05), pulmonary valve Z value (-3.47 +/- 0.59 vs -5.43 +/- 0.94, p <0.05), and ratio of right-to-left ventricular area on the apical 4-chamber view (0.73 +/- 0.06 vs 0.49 +/- 0.03, p <0.05). There were no significant differences in hemodynamic characteristics between the 2 groups. After a follow-up period ranging from 7 to 35 months (mean 18 +/- 10.3), the most recent echocardiograms in the 10 patients showed a mean pressure gradient across the pulmonary valve of 17 +/- 15 mm Hg. All 10 patients had an oxygen saturation of >92%. Transcatheter valvotomy using a radiofrequency guidewire is a safe and effective treatment in selected patients with PA-IVS. Transcatheter valvotomy can be a definitive treatment in PA-IVS patients with a tricuspid valve Z value > or = -0.1, pulmonary valve Z value > or = -4.1 and ratio of right-to-left ventricular area > or = 0.65.

Catheterization↗
PubMed1998

Clinical implications of isolated double aortic arch and its complex with intracardiac anomalies.

From July 1, 1989 to June 30, 1996, a total of six patients, four male and two female, with double aortic arch (DAA) were registered. They aged 16 days to 6.5 years. There were two patients with isolated DAA, and four complicated with intracardiac anomalies. All six patients presented respiratory distress and feeding problem early in life. However, cyanosis, owing to decreased pulmonary blood flow, predominated the clinical picture in each patient having DAA intricated with tetralogy of Fallot (TOF) and pulmonary stenosis, TOF with absent pulmonary valve syndrome, and type II-A tricuspid atresia. DiGeorge syndrome was documented in one patient with TOF and pulmonary stenosis. Expiratory wheezing was remarkable in the patient with TOF and absent pulmonary valve syndrome. Mild cyanosis and heart failure was noted in one patient with ventricular septal defect (VSD), and bicuspid pulmonary valve with mild valvular stenosis. Barium esophagogram showed indentations on esophagus in five patients. Echocardiography was yielding in three infants. Four patients, two isolated and two complex DAA, survived the surgical division of the smaller left aortic arch. One-stage and two-stage operation was performed in patients having DAA intricated with VSD and TOF, respectively. The other two patients with complex DAA remained in close observation owing to the tolerance of symptoms related to intracardiac anomalies.

Aorta, Thoracic↗
PubMed1998

Usefulness of electron beam computed tomography in children with heterotaxy syndrome.

Children with heterotaxy syndrome frequently have complex cardiac and noncardiac malformations requiring detailed diagnostic evaluation for management planning. Direct delineation of these structures by electron beam computed tomography (EBCT) is validated as a means of diagnosis. From July 1995 to March 1997, 32 patients (16 girls, 16 boys) with clinically impressed heterotaxy syndrome were enrolled in this study. After evaluation by echocardiography, EBCT studies were performed. Interpretation of cardiac anomalies was performed by sequential analysis based on these cross-sectional images. The diagnoses were subsequently confirmed by angiocardiography and surgical findings. Twenty-eight patients had bilateral trifurcated bronchi, and most of these (24 of 28) did not have a spleen. Four patients had bilateral bifurcated bronchi, 2 patients had polysplenia, and the other 2 patients had a lobulated single spleen. We found that laterality could be identified by EBCT in all patients. Comparison of diagnostic yield between echocardiography, catheterization, and EBCT showed that EBCT is superior to echocardiography and catheterization in demonstration of pulmonary venous anatomy and presence of a very small rudimentary ventricle. In addition, associated visceral, bronchopulmonary, mediastinal, and intracardiac anomalies could all be clearly delineated by EBCT at the same time. Thus, EBCT is a promising complementary modality for an overall understanding of heterotaxy syndrome.

Abnormalities, Multiple↗
PubMed1998

Successful arterial switch operation in a low-birth-weight neonate who had transposition of the great arteries and advanced necrotizing enterocolitis.

A low-birth-weight (LBW; 1,940 g) girl was born at the gestational age of 36 weeks without any perinatal insult. Transposition of the great arteries (TGA) with a large patent ductus arteriosus (PDA) and interatrial shunt was detected. Stage IIIB necrotizing enterocolitis (NEC) developed 46 hours after birth. She received ileostomy and drainage. Arterial switch operation was successfully performed at 23 days of age when her weight was 1,900 g. The enterostomy was successfully repaired at 104 days of age.

Ductus Arteriosus, Patent↗
PubMed1998

An automatic diagnostic system for CT liver image classification.

Computed tomography (CT) images have been widely used for liver disease diagnosis. Designing and developing computer-assisted image processing techniques to help doctors improve their diagnosis has received considerable interests over the past years. In this paper, a CT liver image diagnostic classification system is presented which will automatically find, extract the CT liver boundary and further classify liver diseases. The system comprises a detect-before-extract (DBE) system which automatically finds the liver boundary and a neural network liver classifier which uses specially designed feature descriptors to distinguish normal liver, two types of liver tumors, hepatoma and hemageoma. The DBE system applies the concept of the normalized fractional Brownian motion model to find an initial liver boundary and then uses a deformable contour model to precisely delineate the liver boundary. The neural network is included to classify liver tumors into hepatoma and hemageoma. It is implemented by a modified probabilistic neural network (PNN) [MPNN] in conjunction with feature descriptors which are generated by fractal feature information and the gray-level co-occurrence matrix. The proposed system was evaluated by 30 liver cases and shown to be efficient and very effective.

Algorithms↗