Biomedical subjects

B C Chang

Publications and source records attributed to B C Chang.

At least 37 records · Page 2Linked to original sources

PubMed1998

Implementation of a low-cost PACS/CR for clinical use in Yonsei Cardiovascular Center.

The PACS/CR for clinical use in Yonsei Cardiovascular Center has been designed and implemented. Our system is open architecture to comply with emerging standards such as DICOM. database SQL, TCP/IP and to reduce operational and maintenance costs, PC-based low cost workstations running Microsoft Windows, database as Microsoft SQL based on Client/Server, Long-term storage using CD-ROM Jukebox are developed. Also, auto routing and image pre-fetching are implemented.

Ambulatory Care Facilities↗

PubMed1997

Design of a medical image processing software for clinical-PACS.

Software modules for interactive display, manipulation and retrieval of medical images have been designed for a Picture Archiving and Communications System (PACS). The target of these modules is not for a high-end diagnostic workstation for radiologists, but for a PC-based low cost clinical workstation for a referring physician. This software is constructed based on a concept of an object-oriented language which is designed to be modular and expandable. It consists of several functional modules: (a) a communication module for image retrieval, (b) a standard module for the interpretation of the DICOM images, (c) a user interface module for the non-computer oriented clinicians and (d) a tool module for viewing and manipulating images as well as editing the annotation.

Image Processing, Computer-Assisted↗

PubMed1997

Adenocarcinoma combined with malignant peripheral nerve sheath tumor of the gallbladder.

Adenocarcinoma of the gallbladder combined with a malignant peripheral nerve sheath tumor (MPNST) in the gallbladder in an 81-year-old woman is reported. The resected gallbladder showed two distinct tumor components, the epithelioid type of MPNST and adenocarcinoma with areas of mucin production. Although the immediate postoperative course was uneventful, a pathologic fracture of her right upper femur developed 4 months after the cholecystectomy. The pathology was determined to be a feature of metastatic MPNST rather than of adenocarcinoma. A whole body bone scan revealed multiple metastases, including the left parietal skull, left ninth rib, seventh thoracic vertebra, and right upper third of the femur. Despite cholecystectomy and postoperative irradiation therapy, she died 6 months after diagnosis of the tumor. Without an autopsy the primary site of the MPNST was unknown. We found that the prognosis was very poor in patients with distal metastatic MPNST, especially in older patients.

Adenocarcinoma, Mucinous↗

PubMed1996

Bilateral tubo-ovarian actinomycosis in the presence of an intrauterine device: a case report.

An uncommon case of actinomycosis found in bilateral tubo-ovarian abscess is presented. Preoperatively, bilateral ovarian tumors were initially suspected by pelvic examination and ultrasonography. The patient received total abdominal hysterectomy and bilateral salpingo-oophorectomy. The initial pathology frozen section report showed abscess without evidence of malignancy. The final pathological finding revealed actinomycosis in bilateral tubo-ovarian abscess. In addition, an intrauterine contraceptive device, Copper-T, was found in the uterine cavity. The radiologic findings, gross pathological feature, histopathological pictures and treatment of pelvic actinomycosis are discussed, with review of the literature in English.

Actinomycosis↗

PubMed1996

Mesial temporal dysembryoplastic neuroepithelial tumor mimicking oligodendroglioma: a case report and review of the literature.

Dysembryoplastic neuroepithelial tumor (DNT) is an uncommon congenital tumor occurring in children. We report a 12-year-old boy who had a focal motor seizure involving his left face 6 months prior to admission. Preoperative computed tomography of the brain demonstrated a focal calcified tumor measuring 2.5 cm in diameter in the right temporal lobe. Initial pathological diagnosis was oligodendroglioma, and postoperative radiotherapy with a total dose of 5000 cGy in 28 fractions over 5&1/2 weeks was given. At follow-up 8 months later, neither clinical nor radiological recurrence was found. Because of the benign clinical course, a review of the surgical specimen was made, which led to the diagnosis of DNT. It is important to distinguish DNT from other tumors that have a worse prognosis. Correct diagnosis may prevent unnecessary radiotherapy or chemotherapy. The pathologic and radiologic diagnostic criteria of DNT are discussed, with a review of the literature.

Brain Neoplasms↗

PubMed1995

Use of a 64 channel computerized cardiac mapping system in arrhythmia surgery.

A multipoint and computerized intraoperative mapping system has been known to be of value in improving the results of surgery for cardiac arrhythmia. It shows great potential as a new tool in the surgical intervention of the more common and lethal types of supraventricular tachyarrhythmias such as atrial flutter and atrial fibrillation. In addition, it also enhances the ability of the investigators to map and ablate the sometimes fleeting automatic atrial tachycardia. The authors developed a 64 channel computerized cardiac mapping system using a microcomputer (Macintosh IIx) and this has been used for basic research in cardiac electrophysiology as well as in arrhythmia surgery. In this system, bipolar electrograms are obtained from 64 different cardiac sites simultaneously at a sampling rate of 1 Ksample/sec and with a continuous and total data storage of up to 30 seconds. When the reference electrode is selected, delay time from the reference point is displayed on a two dimensional diagram of the heart. This system was used in one patient who underwent a surgical ablation of a ventricular tachycardia in whom we observed a ventricular activation sequence involving a variety of rhythms over several minutes. The system design permits easy expansion to a simultaneous sampling from 256 sites. This 64-channel mapping appeared to have the potential to be of great help in our understanding of cardiac arrhythmia as well as in its diagnosis and surgical treatment.

Arrhythmias, Cardiac↗

PubMed1994

In vitro pressure drop comparison between two mechanical valve prostheses.

An hemodynamic evaluation of two mechanical heart valves is presented. A tilting disc valve and a bileaflet valve were incorporated in a mock circulatory system which consists of a closed flow loop with a pneumatically driven flexible diaphragm to simulate the physiologic pulsatile flow. Comparisons between the valves were made on the aortic pressure, ventricular pressure, as well as mean pressure gradient at a systolic duration of 45% and a heart rate of 90 beats per minute. The results showed that the tilting disc valve has higher ventricular pressure and mean pressure gradient than that of the bileaflet valve. This indicates that the tilting disc valve has higher transvalvular flow resistance and energy loss than that of the bileaflet valve. From this study it is demonstrated that the mock circulatory system can be a very useful device to evaluate the prosthetic heart valves in vitro.

Heart Valve Prosthesis↗

PubMed1994

In vitro sound spectral analysis of prosthetic heart valves by mock circulatory system.

A comparative study was made of the sounds produced by normal prosthetic valves (St. Jude Medical, Bjork-Shiley, polymer) with those produced by the same valves but having simulated thrombosis at the stent, hinge, or strut. Comparisons of the closing sound were made for the power frequency spectra associated with individual valves. We used periodogram approach to obtain the spectral characteristics of the valve prostheses. The closing sound of the abnormal mechanical valves displayed lower apparent peak frequency. But the abnormal polymer valve produced higher apparent peak frequency. The results showed that frequency spectra gave information pertinent to the simulated malfunction. Sound spectral analysis is believed to be a simple and a good diagnostic tool for detection of prosthetic valve malfunction. Also it seemed to be superior to other methods such as phonocardiography and echocardiography.

Fourier Analysis↗

PubMed1993

Recurrent ascending myelitis: an unusual presentation of herpes simplex virus type 1 infection.

We report on a healthy female with a unique relapsing transverse myelitis accompanied by herpes simplex virus type 1 (HSV-1) infection. Magnetic resonance imaging showed cord enlargement and increased signal intensity on T1-weighted image with gadolinium enhancement from T-4 to T-10 during the first attack and from C-1 to C-2 during the second episode. She was not diagnosed during the first attack. During the second episode, laboratory studies disclosed IgM and IgG antibodies to HSV at the outset with greater than fourfold increases in antibody levels in the serum and cerebrospinal fluid (CSF). Cells cultured from the CSF were positive for HSV-1 according to the immunofluorescence method. The presence of HVS-1 DNA in CSF was documented by polymerase chain reaction (PCR) technique. Acyclovir was given with a partial recovery. We anticipate that PCR assay of CSF will assist early diagnosis of herpetic central nervous system disorders.

Aged↗

PubMed1991

The surgical treatment of atrial fibrillation. III. Development of a definitive surgical procedure.

On the basis of the known electrophysiologic mechanisms of atrial fibrillation, multiple surgical procedures were designed and tested in dogs to determine the feasibility of developing a surgical cure for human atrial fibrillation. These experimental studies culminated in a surgical approach that effectively creates an electrical maze in the atrium. The atrial incisions prevent atrial reentry and allow sinus impulses to activate the entire atrial myocardium, thereby preserving atrial transport function postoperatively. Since September 1987, this surgical procedure has been applied in seven patients, five with paroxysmal atrial fibrillation of 2 to 9 years' duration and two with chronic atrial fibrillation of 3 and 10 years' duration. All seven patients have been cured of atrial fibrillation and none is receiving any postoperative antiarrhythmic medications.

Adult↗

PubMed1990

Computerized activation sequence mapping of the human atrial septum.

To delineate the propagation of electrical activation in the atrial septum, atrial epicardial and atrial septal maps were recorded intraoperatively using a 156-channel computerized mapping system in 12 patients during sinus rhythm (n = 10), supraventricular tachycardia associated with septal pathways in Wolff-Parkinson-White syndrome (n = 3), atrioventricular (AV) node reentrant tachycardia (n = 4), and atrial flutter (n = 5). The epicardial and septal data were recorded simultaneously from 156 atrial electrodes, digitized, analyzed, and displayed as isochronous maps on a two-dimensional diagram of the atria. During sinus rhythm, the activation wave fronts propagated most rapidly along the large muscle bundles of the atrial septum. During supraventricular tachycardia associated with Wolff-Parkinson-White syndrome, the earliest site of retrograde atrial activation usually corresponded to the position of atrial insertion of the septal pathways. However, the earliest site of activation during orthodromic supraventricular tachycardia was different from that during ventricular pacing in 1 patient with a posterior septal accessory pathway localized by the epicardial mapping study. The data document the rationale for dividing the ventricular end of the accessory pathways (ie, the endocardial technique) rather than the atrial end (ie, the epicardial technique) in patients with Wolff-Parkinson-White syndrome. During AV node reentrant tachycardia, atrial activation data suggested that atrial tissue lying outside the confines of the anatomical AV node is a necessary link in this common arrhythmia. Thus, these atrial septal maps explain why surgical dissection, or properly positioned small cryolesions placed in the region of the AV node, can ablate AV node reentrant tachycardia without altering normal AV node function. The maps recorded during atrial flutter suggest the importance of the atrial septum as one limb of a macroreentrant circuit responsible for the arrhythmia, and imply that atrial flutter is amenable to control by surgical techniques. These studies demonstrate the details of normal atrial septal activation, the importance of the atrial septum in a variety of different atrial arrhythmias, and the basis of and potential for surgical ablation of the most common types of supraventricular arrhythmias.

Adolescent↗

PubMed1989

Surgery for atrial fibrillation.

The observations made under controlled experimental conditions provided us with a clearer understanding of the mechanisms involved in the generation and perpetuation of atrial fibrillation. The magnitude and rapidity of change that occurs in the activation patterns during atrial fibrillation were not appreciated, however, until the arrhythmia was studied in similar detail in humans. These studies provided the scientific basis for devising a surgical treatment for atrial fibrillation that has been successful in three patients. By converting the atrial fibrillation to normal sinus rhythm, all three of the detrimental sequelae of atrial fibrillation have been alleviated in each of these patients. Despite the fact that these clinical results are preliminary at this point, our experience documents that atrial fibrillation can be cured by surgical means. In the absence of other effective forms of therapy and in view of the devastating complications of the arrhythmia, surgical intervention should be considered a viable option for the treatment of atrial fibrillation.

Animals↗

PubMed1985

The constant plasma 18-hydroxycorticosterone to aldosterone ratio: an expression of the efficacy of corticosterone methyloxidase type II activity in disorders with variable aldosterone production.

Aldosterone and 18-hydroxycorticosterone (18-OHB) are produced by the adrenocortical zona glomerulosa. Under normal conditions, plasma 18-OHB levels parallel and are influenced by the same trophic factors that regulate aldosterone production. To evaluate corticosterone-methyl-oxidase II activity, the final step of aldosterone biosynthesis, in conditions associated with chronic derangements of the pituitary-adrenal and/or renal-adrenal axis, we measured the plasma 18-OHB to aldosterone ratio, cortisol, PRA or plasma renin concentration, and potassium (K) in 104 such patients and 15 normal subjects. The 18-OHB to aldosterone ratios in the pituitary-adrenal group were not significantly different from normal regardless of elevated or reduced ACTH and/or cortisol levels [patients with Cushing's syndrome, 3.55 +/- 0.68 (+/-SE); ACTH deficiency, 2.03 +/- 0.34; 21-hydroxylase deficiency, 3.09 +/- 0.23; normal subjects, 2.50 +/- 0.15]. The renal-adrenal group also had normal ratios regardless of plasma renin concentration and K levels [patients with aldosterone-producing adenomas, 2.85 +/- 0.15; idiopathic hyperaldosteronism, 2.14 +/- 0.19; salt-losing nephropathy, 3.06 +/- 0.54; Bartter's syndrome, 2.89 +/- 0.20; isolated (hyporeninemic) hypoaldosteronism, 3.20 +/- 0.39]. Only in patients with 17 alpha-hydroxylase deficiency (230.1 +/- 118.6) was the ratio abnormally high. Chronic perturbations of aldosterone production by ACTH, the renin-angiotensin system, and/or K did not alter this last step of aldosterone biosynthesis (corticosterone-methyloxidase II), as defined by their plasma concentrations. Any influence of these trophic factors must be proximal to the site of 18-OHB production.

18-Hydroxycorticosterone↗

PubMed1980

Thermal dependence of apolipoprotein A-I-phospholipid recombination.

Studies of the recombination of apolipoprotein A-I (apo A-I), the major protein constituent of human high-density lipoprotein, and various synthetic phospholipids, both alone and in mixtures, have been performed. Pure diacyl phospholipids containing homologous fatty acids of the C12, C13, C14, and C15 series, as well as the two positional isomers containing C14 and C16 fatty acids in positions 1 and 2, undergo reaction with the apo A-I protein only near their gel-liquid-crystalline transition temperatures; the degree of reactivity of these phospholipids toward recombination was observed to decrease as the transition temperature increased. The presence of lysolecithin in the incubation mixtures at proportions of 5 mol/mol of protein or lower was not found to have a significant effect on the rate of recombination. Binary mixtures of dimyristoylphosphatidylcholine and dipalmitoylphosphatidylcholine at various proportions react maximally with apo A-I at the onset of the phase transition, as judged by comparison with published phase diagrams; in this case also, the rate of recombination was observed to decline for mixtures with higher phase transition temperatures. These results are interpreted in terms of protein insertion at lattice defects arising from the presence of phospholipid clusters undergoing the phase transition; these clusters are derived from the cooperative and simultaneous melting of a number of molecules, the cooperativity being dependent upon the nature of the phospholipid. It is postulated that phospholipids which melt in a more highly cooperative fashion are more capable of interacting with the apolipoproteins since these phospholipids will possess larger lattice defects during the phase transition.

Apolipoprotein A-I↗

PubMed1979

Synthesis and characterization of a new fluorescent phospholipid.

A novel fluorescent phospholipid, whose structure was tentatively assigned as 1-(2'-thio-1'-hydroxyethyl)-2-(ethylphosphatidyl)isoindole), was synthesized by reacting O-phthalaldehyde and beta-mercaptoethanol with phosphatidylethanolamine. The fluorescent lipid product was purified by silicic acid chromatography. The purity was demonstrated by thin-layer chromatography. This fluorescent phospholipid could not form stable lipid vesicles. However, a mixture of phosphatidylcholine and this fluorescent phospholipid did form stable vesicles after sonication, as demonstrated by Sepharose 4B column chromatography and electron microscopy. The absorption and fluorescence properties of this lipid, both as aqueous micelles or incorporated into vesicles, have been determined. The potential usage of this new fluorescent phospholipid in membrane studies is discussed.

Fluorescent Dyes↗

PubMed1976

Circadian rhythm and effect of posture on plasma aldosterone concentration in primary aldosteronism.

The effect of circadian rhythm and alterations in posture on plasma aldosterone concentration was studied in 13 patients with primary aldosteronism (six adenoma, five idiopathic hyperplasia, two carcinoma) to define the regulatory mechanism in each of these pathologic subtypes. Blood samples for aldosterone, cortisol, renin, and potassium concentrations were obtained every 4 h during prolonged recumbency (32 h) and upright posture (16 h). During recumbency, aldosterone and cortisol followed a normal circadian pattern in patients with adenoma and hyperplasia, with peak values at 0400-0800 h and the nadir at 1600-2400 h. Normalized aldosterone and cortisol values correlated significantly in both groups (adenoma r=+0.66, P less than 0.001; hyperplasia r=+0.42, P less than 0.01). With upright posture, aldosterone levels declined parallel to the normal circadian fall in cortisol in patients with adenoma (r=+0.68, P less than 0.001); whereas aldosterone levels increased in patients with hyperplasia parallel to small increments in renin (r=+0.65, P less than 0.001) and potassium (r=+0.64, P less than 0.001). During the administration of dexamethasone, aldosterone no longer correlated with cortisol in patients with adenoma but continued to correlate with renin during upright studies in patients with hyperplasia (r=+0.77, P less than 0.01). Aldosterone circadian rhythm was abnormal in patients with carcinoma and no effect of posture was noted. Unilateral adrenalectomy restored the normal postural relationship in four patients with adenoma. These studies suggest that aldosterone secretion is under continuous ACTH control regardless of posture in patients with adenoma, whereas persistent adrenal responsiveness to small increments in renin and/or potassium mediate the postural increase in plasma aldosterone in patients with hyperplasia. True adrenal autonomy occurs only in patients with adrenal carcinoma and when ACTH is suppressed in those with adenoma.

Adult↗

PubMedDate not supplied

The use of high-resolution computed tomography in the evaluation of pulmonary hemodynamics in patients with congenital heart disease: in pulmonary vessels larger than 1 mm in diameter.

High-resolution computed tomography (HRCT) was carried out in 36 patients with congenital left-to-right shunt disease and 10 normal control subjects to assess the feasibility of CT in the evaluation of pulmonary hemodynamics. The patients had a left-to-right or a bidirectional shunt and the hemodynamic data obtained by cardiac catheterization in these patients were compared to the information obtained by CT imaging. The pulmonary/systemic blood flow (Q(p)/Q(s)) ratio and pulmonic/systemic resistance (R(p)/R(s)) ratio had a significant correlation with the pulmonary artery/bronchus (PA/Br) ratio (r = 0.54 and r = -0.37, respectively) and pulmonary vein/bronchus (PV/Br) ratio (r = 0.66 and r = -0.66, respectively), and the R(p)/R(s) and mean PA pressure also showed a significant correlation with the PA/PV ratio (r = 0.53 and r = -0.61, respectively) in the mid-lung field when accompanying bronchi were 4. 0-5.9 mm in diameter. There was no correlation between the hemodynamic data and the size of the central and hilar PA or with the rate of PA tapering. With HRCT, it is possible to evaluate pulmonary hemodynamics in patients with congenital heart disease with a left-to-right or bidirectional shunt, particularly R(p)/R(s) and mean PA pressure, which have been very difficult to obtain noninvasively. The small-sized pulmonary vessel/Br ratio or the small-sized PA/PV ratio could offer very useful information, but the dimension of the central PA provided the least useful information.

Adolescent↗

PubMedDate not supplied

Volume reduction surgery for end-stage heart failure: experience in Korea.

Partial left ventriculectomy (PLV) is regarded as one of the alternatives to heart transplantation for idiopathic dilated cardiomyopathy (d-CMP). Between June 1996 and March 2000, 20 patients underwent left ventricular volume reduction surgery at five major cardiac centers in Korea. PLV was performed in 16 patients with d-CMP and in 1 patient with ischemic CMP. The modified Dor procedure was performed in three patients; two patients with d-CMP and one patient with ischemic CMP. Median age was 35 years (range 3-64 years). There were 13 male and 7 female patients; there were 4 patients in Class III and 16 patients in Class IV. Among the 16 patients in Class IV, 5 patients were inotropic dependent, 2 patients were resuscitated from cardiac arrest or shock in hospital, and 1 patient was treated with intra-aortic balloon pumping. Operative technique for PLV was the same as described by Batista and colleagues. For the modified Dor procedures, the apical left ventricle was opened and a circumferential pursestring suture was placed at the base of both papillary muscles to reduce the diameter of the left ventricle concomitant with mitral annuloplasty. Mitral valve repair was performed in 15 patients and mitral valve replacement was performed in 1 patient. Moderate-to-severe tricuspid regurgitation was noted in 12 patients (with tricuspid annuloplasty in 11 of these patients and replacement in 1 patient). Postoperatively, there were seven operative deaths after PLV and one death after the modified Dor procedure. Cause of death after PLV was right heart failure in four of the seven cases, sepsis in one case, and ventricular tachyarrhythmia in the remaining two cases. After the modified Dor procedure, there was one operative death with left ventricular failure. Postoperatively, mean ventricular end-diastolic dimension markedly decreased from 75.3 mm to 50.9 mm. However, this dimension had increased slightly to 58.2 mm, an average observed 22 months later. Mean left ventricular ejection fraction (LVEF) improved significantly from 20.6% to 33.5% (p < 0.0001), but decreased to 28.5% on average 22 months later (p = 0.058). Eleven patients were discharged from the hospital and followed-up for a mean of 20.2 months (range 1-41 months). During the early postoperative period, most were in good condition. However, heart failure progressed with mitral regurgitation in four patients, two of whom underwent heart transplantation. In conclusion, PLV for d-CMP seems to be an effective alternative surgical procedure to heart transplantation in Korea. The modified Dor procedure may be another alternative to transplantation for left ventricular volume reduction. However, in patients showing progression of heart failure, early intervention with ventricular assist or heart transplantation will be necessary. Also, further studies will be necessary for selection criteria and for prevention of ventricular tachyarrhythmia.

Adolescent↗