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H J Chang

Publications and source records attributed to H J Chang.

At least 55 records · Page 3Linked to original sources
PubMed1997

A case of intraductal papillary tumor of pancreas associated with mucinous ductal ectasia.

Intraductal papillary neoplasm associated with mucinous ductal ectasia is an uncommon cystic disease of the pancreas. This tumor is characterized by the multilocular cyst lined by mucin producing cells with variable degrees of atypia and ductal ectasia. In addition, this tumor has a favorable prognosis in contrast to other mucinous cystic tumor of the pancreas. Reports on intraductal mucin producing tumor are quite limited and most of them are found in Japanese literature. We report a case of intraductal papillary adenocarcinoma with marked dilatation of the pancreatic duct filled with mucin in a 72-year-old female patient.

Adenocarcinoma, Mucinous↗
PubMed1996

Ochrobactrum anthropi meningitis in pediatric pericardial allograft transplant recipients.

An epidemiologic investigation was done after 3 patients contracted Ochrobactrum anthropi meningitis at one hospital in October 1994. Neurosurgical patients with pericardial tissue implants were at greater risk of infection than other neurosurgical patients (3/14 vs. 0/566; P<.001). Cultures of implants removed from 2 case-patients, an implant at implantation, a nonimplanted pericardial tissue, and an unwrapped but unopened bottle of Hank's balanced salt solution (HBSS) grew O. anthropi. Patient and tissue isolates had identical genotypes; the isolate from the HBSS bottle had a unique genotype. Culture samples from an unopened HBSS bottle and from pericardial tissue grew Pseudomonas stutzeri of the same genotype; however, no P. stutzeri infections were detected. The investigation documented intrinsic P. stutzeri contamination of HBSS. O. anthropi contamination of tissues occurred during processing, possibly due to extrinsic contamination of HBSS. Active surveillance is needed to detect infection in patients receiving transplanted tissues, and rigorous infection control practice are necessary during tissue harvesting and processing to ensure sterility.

Alcaligenes↗
PubMed1995

Canadian physicians considering a move to US can face complicated immigration process.

American recruiters are busily trying to coax Canadian physicians to move south of the border to practise, but Canadians must remember that the immigration process can be both lengthy and complicated. In this article, immigration lawyer Henry Chang looks at the requirements that must be met before permanent-resident status is granted by the US.

Canada↗
PubMed1995

Multiplane transesophageal echocardiography in the diagnosis of congenital coronary artery fistula.

The purpose of this study was to examine the advantages of multiplane transesophageal echocardiography in the diagnosis of congenital coronary artery fistula, specifically in depicting the origin, the course, and the drainage site. Seven consecutive patients ranging in age from 20 to 72 years with a suspected coronary artery fistula underwent conventional transthoracic and multiplane transesophageal echocardiographic studies between March 1993 and July 1994. When a coronary artery fistula was noted, the origin, the course, and the drainage site were carefully searched for. All patients then underwent a cardiac catheterization with the performance of coronary angiography. A large right coronary artery fistula was detected in three patients; one of them had a drainage to the posterior left ventricle, one to the lateral right ventricle, and the other to the medial aspect of the right ventricle just below the insertion of the septal leaflet of the tricuspid valve. A small coronary artery fistula arising from the left coronary artery was noted in four patients, two from the left anterior descending artery and the other two from the left circumflex artery. Three of these four patients had a drainage to the main pulmonary artery and one to the left ventricle. The drainage site was clearly depicted in all seven patients, whereas the origin and the course were precisely defined in five patients by using multiplane transesophageal echocardiographic examination. The multiplane transesophageal echocardiography provides a panoramic view of the coronary artery and the fistulous vessel with a precise definition of the origin, the course, and the drainage site of the fistula. Therefore it is the noninvasive diagnostic mode of choice.

Adult↗
PubMed1995

HLA and ethnic associations among systemic sclerosis patients with anticentromere antibodies.

SSc with ACAs is characterized by limited cutaneous involvement and, in most patients, a mild protracted course. We have studied 104 SSc patients, 47 with ACAs and 57 who were negative for both ACAs and anti-topo I antibodies, for HLA-DR and -DQ associations using DNA typing techniques. Normal controls consisted of 181 healthy individuals. A significant association was observed in the ACA-positive patients with DQB1-0501 (p = 0.001, RR 2.6). There was also a significant decrease in the frequency of DQB1-0201 (p = 0.01, RR 0.33). In addition, the ACA-positive SSc patients were significantly different ethnically from both the other SSc patients and the normal controls (p = 0.004). When patients were stratified according to their ethnic origin and the analysis of HLA associations was repeated, the HLA associations persisted. These results strongly suggest that the development of SSc with ACAs is associated with particular DQB1 alleles, and also that ethnic origin plays a role in disease susceptibility.

Adult↗
PubMed1995

Diagnosis of coronary artery dissection following blunt chest trauma by transesophageal echocardiography.

How to differentiate relevant from trivial cardiac injury in blunt chest trauma has been an ongoing debate. In a 32-year-old victim of a motorcycle crash, the electrocardiographic pattern of an acute anterior wall myocardial infarction was identified as being due to a dissection, after an intimal flap in the proximal left anterior descending artery was noted on transesophageal echocardiography.

Adult↗
PubMed1994

Alteration in multijoint dynamics in patients with bilateral knee osteoarthritis.

OBJECTIVE: To document the alterations of joint motion and torque in patients with bilateral knee osteoarthritis (OA), using a well-defined functional maneuver, the sit-to-stand (STS) task. METHODS: Twelve patients with bilateral knee OA and 12 age-, sex-, and height-matched control subjects performed the STS maneuver from a stool of a standard height at their natural speeds. A motion analysis system and 2 force platforms were employed to determine the dynamic joint motion and the resultant joint torques at the ankle, knee, and hip joints. RESULTS: The results showed that OA patients exhibited substantially reduced knee extension torques, accompanied by other alterations in initial sitting posture (more extended knee and more plantar-flexed ankle), movement duration (increased), dynamic range of motion at the knee (reduced), and extension torques at the hip (increased). CONCLUSION: The alterations in joint dynamics among patients with knee OA may have revealed an adaptive motor behavior characterized by redistributing the load from impaired to less-impaired or nonimpaired joints through multijoint dynamics. Two major potential pitfalls of such a movement strategy have subsequently been postulated.

Aged↗
PubMed1994

Severe systemic sclerosis with anti-topoisomerase I antibodies is associated with an HLA-DRw11 allele.

SSc is an autoimmune connective tissue disease in which strong HLA associations have not been described. Anti-topo I antibodies are recognized, in general, in SSc patients with diffuse cutaneous involvement, whereas anti-ACAs are found in individuals with limited cutaneous involvement. We studied 95 Caucasian SSc patients, 44 with anti-topo I antibodies and 51 with neither anti-topo I nor ACA, for HLA-DR associations by using DNA typing techniques. We analyzed 181 normal Caucasian individuals in the same fashion. A significant association was observed in the anti-topo-I-positive patients with DRw11 (p = 1.7 x 10(-6), RR 4.2). The distribution of DRw11 alleles in these patients was significantly different from that observed in controls and could be accounted for by an increase in the frequency of the DRB1*1104 allele (p = 1.2 x 10(-9), RR 9.5). The DRw11 alleles were also associated with SSc with more tendon friction rubs (p = 0.006), which is a marker of more severe disease. In addition, a strong association was observed with anti-topo I antibodies and a particular sequence (aa 71-77) of the DQB1 chain (p = 0.02, RR 2.2). HLA associations in the case of SSc patients with anti-topo I antibodies are complex and involve at least two genes: HLA-DRw11, which appears to play a major role in determining the severity of the disease, and a DQ sequence, which associates with the development of the anti-topo I antibodies.

Adult↗
PubMed1994

Use of transesophageal echocardiography for evaluation of resectability of lung cancer.

BACKGROUND: When patients with lung cancer are to undergo surgical resection, chest x-ray and computed tomography (CT) are widely used for evaluation of staging and of the resectability of the lesion. Unfortunately, the above methods cannot always provide sufficient information about resectability and some patients undergo unnecessary operations. Transesophageal echocardiography (TEE) has opened a new window for viewing cardiac structure and function. By TEE, one can also image the surrounding tissues and great vessels under continuous monitoring. MATERIALS AND METHODS: We pre-operatively applied the awake TEE method in twenty whose chest CT showed suspected invasion of the heart by the tumor. RESULTS: Our experience showed the following: (1) TEE can clearly identify whether lung cancer has invaded the heart and/or great vessels and therefore avoiding unnecessary operation; (2) Two patients had tumor seen abutting epicardium and/or aorta without invasion (under continuous imaging). Two patients had tumor compressing the right and left atrium with intact but not invading pericardium, and underwent successful surgical resection. CONCLUSION: We concluded that it is useful to apply TEE preoperatively in evaluating the resectability of the lung cancer especially when a chest CT shows suspicion of local invasion of the heart and great vessels; thus unnecessary thoracotomy can be avoided.

Adult↗
PubMed1993

Midkine that promotes survival of fetal human neurons is produced by fetal human astrocytes in culture.

Midkine (MK), a retinoic acid responsive gene product, is a novel heparin-binding growth factor with an apparent molecular weight of 14-kDa. In fetal human neuron cultures, addition of recombinant human MK (10-100 ng/ml) resulted in a 3-fold increase in the number of surviving neurons under the serum-free culture condition. Production of MK was identified in the conditioned medium of astrocyte-enriched cultures by immunoblotting but not in the medium of neuron-enriched cultures. The level of MK production was not affected by treatment with retinoic acid. These results indicate that in the developing human central nervous system, astrocytes secrete MK that exhibits potent trophic activity to neurons.

Animals↗
PubMed1993

Pattern association and retrieval in a continuous neural system.

This paper studies the behavior of a large body of neurons in the continuum limit. A mathematical characterization of such systems is obtained by approximating the inverse input-output nonlinearity of a cell (or an assembly of cells) by three adjustable linearized sections. The associative spatio-temporal patterns for storage in the neural system are obtained by using approaches analogous to solving space-time field equations in physics. A noise-reducing equation is also derived from this neural model. In addition, conditions that make a noisy pattern retrievable are identified. Based on these analyses, a visual cortex model is proposed and an exact characterization of the patterns that are storable in this cortex is obtained. Furthermore, we show that this model achieves pattern association that is invariant to scaling, translation, rotation and mirror-reflection.

Animals↗
PubMed1992

Nature of dual atrioventricular node pathways and the tachycardia circuit as defined by radiofrequency ablation technique.

OBJECTIVES: A comprehensive electrophysiologic study followed by selective radiofrequency ablation from three sites was performed in patients with atrioventricular (AV) node reentrant tachycardia to better delineate the nature of the tachycardia circuit. BACKGROUND: We postulated that the retrograde fast pathway is the anterior superficial group of transitional cells and the slow pathway is the compact node with its posterior input of transitional cells. Twenty-three consecutive patients were studied. In nine, the atria could be dissociated from the tachycardia by delivery of an atrial extrastimulus during tachycardia. METHODS: Radiofrequency ablation was performed with three approaches. The anterior approach was designed to interrupt the anterior superficial atrial input to the compact node, the posterior approach to interrupt the posterior atrial input to the compact node and the inferior approach to destroy the compact node itself. RESULTS: Selective ablation of the retrograde fast pathway was achieved in seven patients, six with the anterior and one with the inferior approach. Anterograde fast pathway conduction was not affected, whereas retrograde fast pathway conduction was either abolished or markedly depressed. None had induction of echoes or tachycardia after ablation. Selective ablation of the slow pathway was successful in 13 patients, 1 with anterior, 3 with posterior and 9 with inferior approaches. In these 13 patients, both anterograde and retrograde fast pathway conduction were not affected, the dual pathway physiology was abolished and the tachycardia was not inducible after ablation. Ablation of both the retrograde fast pathway and the slow pathway occurred with the inferior approach in three patients. CONCLUSIONS: We conclude that the retrograde fast pathway is likely to be the anterior superficial group of transitional cells, whereas the slow pathway is the compact node and its posterior input of transitional cells. A barrier seems to exist between the atrium and the tachycardia circuit. In a broad view of the AV node structure, the tachycardia circuit is confined to the node.

Atrial Function↗
PubMed1992

Rehabilitation and biomechanics.

Advances in our understanding of disability is important to the development of new rehabilitation ideas for patients with rheumatic disease. Large epidemiologic and focused clinical and laboratory studies that deal with risk factors and treatment for physical and social disability, exercise, gait analysis, and biomechanics are reviewed.

Arthritis↗
PubMed1992

Effect of fibrin matrix on growth of glomerular cells.

Rat glomerular cells were grown either in or on fibrin clots prepared from rat plasma to assess the effect of native fibrin on the growth of glomerular epithelial and mesangial cells. Progressive fibrinolysis was observed in glomerular explant cultures without epsilon-aminocaproic acid (EACA), an inhibitor of plasminogen activation. The lytic areas extended as the cell number of glomerular explant outgrowths increased. Glomerular cultures containing 0.5% EACA showed complete inhibition of fibrinolysis. Under this condition, the glomerular outgrowths developed only when the glomerular explants were seeded on the surface of fibrin matrix. While the explants were embedded in the fibrin matrix, few cells could grow out of explants. The more prosperous growth of glomerular epithelial cells in the lytic areas and the lack of intimate binding of glomerular epithelial cell membrane with fibrin fibers implied that fibrin might hinder the outgrowth of glomerular epithelial cells. The mesangial cells, whether growing on the surface of or embedded in the fibrin matrix, showed no fibrinolytic activity. Inhibition of fibrinolysis did not alter the growth pattern of mesangial cells. In addition, mesangial cells exhibited extensive binding of fibrin fibers on their cell surface and developed conspicuous arborization of their cell processes. These features suggested a close affinity between mesangial cells and fibrin matrix. These experiments have addressed our attention to the particular roles of the visceral epithelial cells and mesangial cells in the pathogenesis of fibrin-related glomerulonephritis.

Animals↗
PubMed1990

Interfacial strengths of various alloy surface treatments for resin-bonded fixed partial dentures.

A practical method for bonding or rebonding the resin-bonded retainer is eagerly being sought by general practitioners. This research introduces a new test apparatus for evaluating bond strength of base metal alloys after various alloy surface treatments. Five commercial base metal alloys and a resin luting cement for resin-bonded fixed partial dentures were examined. Sandblasting, oxidation, or etching treatment were determined to be effective in increasing the adhesive strength for the tested alloys. No statistical differences between various surface treatments were found for bonding of Unitbond metal. Inexpensive sandblasting, along with ultrasonic washing, provided superior bonding strengths for Biobond II and Litecast B materials. Electrochemical treatment was suitable for Wiron 77 and Lab metals.

Acid Etching, Dental↗
PubMed1990

Cell therapy in children with Down syndrome: a retrospective study.

Cell therapy, the administration of freeze-dried or lyophilized cells derived from fetal tissue of animals, has been suggested and accepted by some parents as a treatment for Down syndrome. Such therapy regimens have been purported to ameliorate dysmorphic features and to result in improvement in IQ, motor skills, social behavior, height, language, and memory. Interest in this therapy continues despite a lack of empirical support for its use and its illegality in the United States. In this study, 190 subjects of whom 21 had received cell therapy (from sources external to this study) were studied for 18 variables in the areas of growth, motor development, cognitive development, and adaptive/social status. Comparing the cell-treated group with a control group matched for sex, age, socioeconomic status, and cardiac history showed no statistically significant differences for any of the developmental or growth variables measured. These findings fail to support continued claims of improved functioning following cell therapy in persons with Down syndrome.

Adolescent↗