Biomedical subjects

H Chang

Publications and source records attributed to H Chang.

At least 19 recordsLinked to original sources

PubMed1992

Molecular cloning and characterization of catechol 2,3-dioxygenases from biphenyl/polychlorinated biphenyls-degrading bacteria.

Catechol 2,3-dioxygenases were cloned from Alcaligenes sp. KF711, Pseudomonas putida KF715, and Achromobacter xylosoxidans KF701 which are biphenyl/polychlorinated biphenyls-degrading bacteria. All of the cloned enzymes were purified by preparative polyacrylamide gel electrophoresis (PAGE). The purified catechol 2,3-dioxygenases were significantly different from one another in ring-fission activities to catechol and its derivatives. The catechol 2,3-dioxygenase from Alcaligenes sp. KF711 exhibited higher ring-fission activity to 4-chlorocatechol than those from P. putida KF715 and A. xylosoxidans KF701. In electrophoretic mobilities, the three enzymes were different from one another on nondenaturing PAGE but the same on SDS-PAGE.

Alcaligenes↗

PubMed1992

Synthesis and anticonvulsant activity of enaminones.

A new series of novel enaminones has been synthesized from cyclic beta-dicarbonyl precursors which were condensed with morpholine, pyrrolidine, phenethylamine, hydrazines, substituted benzyl amines, and substituted anilines. These compounds were subsequently evaluated for anticonvulsant activity in a variety of anticonvulsant models by the National Institute of Neurological and Communicative Disorders and Stroke and in our laboratory. Several of these compounds exhibited potent anticonvulsant activity with a remarkable lack of neurotoxicity. The most active analog, methyl 4-[(p-chlorophenyl)amino]-6-methyl-2-oxo-cyclohex-3-en-1-oate++ + (27), was protective in the maximal electroshock (MES) seizure test in the rat with an oral ED50 of 5.8 mg/kg with no toxicity noted at doses up to 380 mg/kg, thus providing a protective index (TD50/ED50) of greater than 65.5. A similar protective index for 27 was noted upon intraperitoneal (ip) administration in mice. The anticonvulsant effect of 27 occurred within 15 min of administration and the compound remained active beyond 4 h. Compound 27 was also active in the rat corneal kindled model. The application of Free-Wilson analysis to structure-activity correlation in this series is discussed.

Amines↗

PubMed1992

Association of a 59-kilodalton immunophilin with the glucocorticoid receptor complex.

Immunophilins, a family of proteins that exhibit rotamase (peptidyl-prolyl cis-trans isomerase) activity in vitro, are expressed in many organisms and most tissues. Although some immunophilins can mediate the immunosuppressive actions of FK506, rapamycin, and cyclosporin A, the physiological role of the unligated proteins is not known. A 59-kilodalton member of the FK506- and rapamycin-binding class was found to associate in the absence of these drugs with two heat shock proteins (hsp90 and hsp70) and the glucocorticoid receptor (GR). Together, these proteins make up the inactive GR, thus biochemically linking two families of proteins proposed to be involved in protein folding and assembly as well as two potent immunosuppressive modalities.

Amino Acid Isomerases↗

PubMed1992

Characterization of catechol 2,3-dioxygenases.

Three catechol 2,3-dioxygenases for biphenyl, naphthalene/salicylate, and toluene/xylene oxidation were cloned from Achromobacter xylosoxidans KF701, Pseudomonas putida (NAH7), and Pseudomonas sp. (pWWO). The cloned catechol 2,3-dioxygenases were identified by enzymatic activity assay in addition to yellow bands on polyacrylamide gel after electrophoresis and activity staining. All of the cloned catechol 2,3-dioxygenases exhibited their highest activities on catechol as a substrate compared with catechol derivatives including 4-chlorocatechol, 3-methylcatechol, and 4-methylcatechol. The cloned catechol 2,3-dioxygenases are not fused proteins but were significantly different from one another in their electrophoretic mobilities on nondenaturing 7.5%-polyacrylamide gel.

Alcaligenes↗

PubMed1992

Dynamic response of the occipito-atlanto-axial (C0-C1-C2) complex in right axial rotation.

The torque-angular deformation in right axial rotation until failure of the ligamentous occipito-atlanto-axial complex subjected to variable loading rate (dynamic) axial torque was characterized using a biaxial MTS system. A special fixture and gear box that permitted right axial rotation of the specimen until failure without imposing any additional constraints were used to obtain the data. The specimens were divided into three groups and tested until failure at three different dynamic loading rates: 50, 100, and 400 degrees/s. A previous study by the authors provided data for quasi-static (4 degrees/s) loading conditions. The torque versus rotation curves can be divided into two straight regions and two transition zones. The plots clearly indicated that at loading rates higher than 4 degrees/s, the specimens became stiffer in the region of steadily increasing resistance prior to failure. The increase in stiffness was maximum at 100 degrees/s. The stiffness decreased somewhat at 400 degrees/s in comparison with 100 degrees/s, but this decrease was not significant. The resulting torque-right axial rotation curves were also examined to estimate the magnitude of maximum resistance (torque) and the corresponding angular rotation value. The average maximum resistance torque increased from 13.6 Nm at 4 degrees/s to 27.8 Nm at 100 degrees/s. The corresponding right angular rotation data (65-78 degrees), however, did not show any significant variation with loading rate. Posttest dissection of the specimens indicated that the type of injury observed was related to the rate of axial loading imposed on a specimen during testing.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

PubMed1992

Development of a computer model to predict strains in the individual fibers of a ligament across the ligamentous occipito-atlanto-axial (C0-C1-C2) complex.

A fresh ligamentous occipito-atlanto-axial (C0-C1-C2) complex was appropriately prepared and serially sectioned into thin slices along the transverse planes. The bony outlines from these slices were digitized and assembled in the proper manner to obtain a three-dimensional model of the complex using the AutoCAD system. Various ligaments were identified on the model and strains in individual fibers of a ligament were predicted based on the principles of rigid body mechanics. The ligament behaviors in axial rotation, flexion, and extension modes were analyzed. The capsular ligament fibers were predicted to undergo strains in all modes. Furthermore, these ligaments experienced the largest strain among the ligaments analyzed. Fibers within a ligament were found to respond differently; some were more active than the others and some did not experience any strain at all. A differential behavior in the right and left side alar ligament fibers was also found in axial rotation. The transverse ligament was predicted to wrap around the dens during axial rotation. The strain within a fiber was found to be a function of the initial length (ligament laxity) and its distance from the center of rotation.

Atlanto-Axial Joint↗

PubMed1992

Meniscus-like synovial fold in the atlantoaxial (C1-C2) joint.

Some of the synovial joints in the human body have a fibrocartilaginous disc interposed between the joint surfaces to absorb or evenly distribute loads. Examples of fibrocartilagenous discs include the intervertebral disc, knee joint meniscus, and triangular fibrocartilages in the distal radioulnar joint and the acromioclavicular joints. The joint capsule and the surrounding tissue from nine cervical spines (18 C1-C2 joints) were dissected and prepared for gross examination and histology. We found meniscus-like synovial folds in 13 of the 18 atlantoaxial joints. These folds were located at the anteromedial and posteromedial aspect of the joint. Each synovial fold was of semilunar shape, with a thickened outer edge and thin inner edge giving a wedge-shape cross section. In one case, the synovial fold was grossly similar in appearance to a knee joint meniscus, and on histological examination there was evidence of cartilagenous metaplasia in part of the fold. The findings are compared with the limited data reported in the literature.

Aged↗

PubMed1992

A human lymphoma cell line with multiple immunoglobulin rearrangements.

The development of a cell culture system efficient in the establishment of lymphoma cell lines has made it possible to dissect basic biological and molecular aspects of lymphoma cells. We have established a lymphoma cell line from a patient with B cell lymphoma. The cell line has a complex karyotype with translocations involving bands 8q24, 14q32, and 18q21. Molecular analysis revealed that the Myc gene was rearranged; we were unable to demonstrate rearrangement of the Bcl-2 gene. Evaluation of the structure of the heavy chain Ig genes revealed that the cell line carried the same rearrangements as the cells from which the cell line was derived. The pattern of rearrangement, however, was unusual in that there were at least four rearranged bands when DNA cut with HindIII was probed with a fragment of the heavy chain joining region. To further characterize the cell line, subclones were derived. Individual subclones had the same pattern of rearrangement as the parent cell line. The results of these studies provide evidence that multiple rearranged Ig genes may be present in a single clone of cells.

Gene Rearrangement↗

PubMed1992

Constitutive production of the interleukins IL-5 and IL-6 by the lymphoma cell line OCI-Ly 17 derived from a patient with malignant lymphoma and hypereosinophilia.

Peripheral blood cells of a patient with diffuse large cell non-Hodgkin's lymphoma presenting with hypereosinophilia were used to establish an EBV negative lymphoma cell line termed OCI-Ly17. Cells of the line stained positive for CD2 and CD5 determinants and demonstrated rearrangement of the T-cell receptor beta chain. The immunoglobulin heavy chain gene was found to be in germ line configuration. Northern blot studies using probes for IL-1 alpha, IL-3, IL-4, IL-5, IL-6, and GM-CSF showed message for IL-5 and IL-6. Supernatants of the cell line were evaluated on normal non-adherent, E-rosette depleted bone marrow cells to determine the presence of growth promoting activities for clonogenic eosinophilic progenitors. Eosinophilic colonies were observed. Their frequency depended upon the amount of supernatant added to the cultures. The growth promoting activity in the supernatant was reduced in a dose dependent manner by preincubation with increasing concentrations of anti-IL-5 antibodies. The supernatants of the cell line were also tested on the IL-6 sensitive human myeloma line OCI-My4 and myeloma colonies grew in response. This stimulatory activity within the supernatant was neutralized by addition of increasing concentrations of anti-IL-6 antibodies. Although producing IL-5 and IL-6 constitutively, the lymphoma line did not increase proliferation in response to either interleukin, nor did it show a reduced proliferative rate when antibodies to IL-5 or IL-6 were added to the cultures.

Aged↗

PubMed1992

Growth of human lymphoma cells in SCID mice.

Two EBV-negative human lymphoma cell lines raised in this laboratory and peripheral blood cells of a patient with large cell lymphoma in leukemic phase were injected intravenously or intraperitoneally into C.B.17 SCID mice. One line (OCI-LY18) was derived from the pleural fluid of a patient with a large cell, immunoblastic malignant lymphoma. Cells of this line are of B cell origin and characterized by multiple rearrangements of the JH locus. The second line (OCI-LY17) was grown from the peripheral blood of a patient with a large cell lymphoma of T-cell phenotype which has characteristic rearrangement of the T-cell receptor beta chain. The cells directly obtained from a patient with large cell non-cleaved malignant lymphoma were of B-cell origin. Animals carrying OCI-LY18 developed large tumor masses within 6-8 weeks of inoculation. The tumors were detected in the intestine, mesentery, retroperitoneum, lymph nodes, spleen, lung and kidney. The masses resembled the primary tumor with respect to histological appearance and immunological phenotype. It was possible to generate secondary cell lines from the tumors found in the inoculated SCID mice. Injection of one of these secondary cell lines into SCID mice resulted in the rapid development of lymphoma and as few as 10 cells were sufficient to establish the disease in the inoculated animals. In contrast cells of OCI-LY17 produced small tumor aggregates that did not appear to progress over time and did not cause death of the animals.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1992

T lymphocyte changes in open heart surgery.

To investigate the effect of open heart surgery on T lymphocytes and their subpopulations, 20 patients, who had undergone moderate- to high-dose fentanyl anesthesia and a cardiopulmonary bypass (CPB), were studied using flow cytometry techniques and monoclonal antibodies during and after surgery. The ages of these patients ranged from four to 61 years with eight being male and 12 being female. The disease entity consisted of four with coronary, six with congenital and 10 with valvular heart disease. No cyanotic patients were included in this study. Peripheral blood samples were collected before anesthesia, immediately before the surgical incision, on the first postoperative day (POD1) and on the second postoperative day (POD2), respectively. We found no significant changes in the percentage of total T cells (T3), or helper (T4) and suppressor (T8) T cells during anesthesia before the surgical incision. On POD1, all T lymphocyte subset percentages decreased significantly when compared to pre-operative values (total T cells: 58.4 +/- 12.6 vs 24.4 +/- 8.4, helper T cells: 33.3 +/- 10.1 vs 15.4 +/- 6.3, suppressor T cells: 23.0 +/- 6.4 vs 10.0 +/- 4, all p less than 0.001) but returned to preoperative levels on POD2. Throughout the study period, there were no significant changes in the T helper cell to T suppressor cell ratio. In spite of the transient decrease in T lymphocytes and their subpopulations, no clinical evidence of infection was noted in any patient.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1992

Effects of fibrin glue on hemostasis.

In order to decrease complications following incomplete hemostasis, we tried to make a safe, efficient and highly concentrated fibrin glue by thawing single-donor fresh frozen plasma. Using a unique animal model, in which arterial bleeding was created, fibrin glue and some related hemostatic agents were tested to evaluate their hemostatic effectiveness. The results demonstrated that: 1) the concomitant use of cryoprecipitate-thrombin tissue glue with adjuvant (aprotinin or calcium chloride) had a better hemostatic effect than the use of cryoprecipitate-thrombin tissue glue alone (p < 0.05); 2) impregnation of fibrin glue with a suitable vehicle was advisable to accelerate the coagulation plug formation and to enhance the mechanical strength of the adhesive plug; 3) Gelform, used as a vehicle to hold the fibrin glue, had a more efficient hemostatic effect than gauze, collagen fleece and Surgicel (p < 0.05); 4) systemic heparinization attenuated the effectiveness of the hemostatic agents and aggravated the bleeding problem, but a low hematocrit level did not; 5) fibrin glue had its own limitations, especially under systemic heparinization, on hemostatic effectiveness in a high-pressure system. Understanding the characteristics of fibrin glue, as mentioned above, definitely improved the hemostatic effectiveness of the glue, especially after failure of the usual methods of controlling bleeding.

Animals↗

PubMed1992

The role of endothelin-1 during ischemia-reperfusion injury.

In order to investigate the role of endothelin-1 during ischemia-reperfusion injury, 80 adult male Wistar rats were subjected to three hours of ischemia and one hour of reperfusion. Animals were evenly divided into eight groups. The rats in group 1 served as the normal control group, while the rats in group 2 received an intravenous infusion of endothelin-1 in a dosage of 0.5 ng/kg/min, group 3 in a dosage of 5 ng/kg/min, and group 4 in a dosage of 50 ng/kg/min. The rats in group 5 were infused with angiotensin II (10 ng/kg/min). The rats in group 6 received an intravenous infusion of 10,000 units of superoxide dismutase and 10,000 units of catalase. Group 7 rats were infused with endothelin-1 (50 ng/kg/min), superoxide dismutase (10,000 units), and catalase (10,000 units). Group 8 rats received an infusion of angiotensin II (10 ng/kg/min), superoxide dismutase (10,000 units) and catalase (10,000 units). The infusions were given during the reperfusion period. After one hour of reperfusion, the gastrocnemius and soleus muscles of the experimental animals were excised and assayed for ischemia-reperfusion injury by measuring triphenyltetrazolium chloride (TTC) reduction. The results showed that the limb activity of the ischemic extremity was 40.33 +/- 2.75% in group 1, 41.62 +/- 4.08% in group 2, 14.42 +/- 3.14% in group 3, 4.43 +/- 1.05% in group 4, 23.81 +/- 3.51% in group 5, 57.23 +/- 4.52% in group 6, 31.79 42- 3.63% in group 7, and 27.39 +/- 3.95% in group 8. Endothelin-1 reduced the limb activity in a dose-dependent manner.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1992

Hyperamylasemia following cardiopulmonary bypass.

In order to study the occurrence of postbypass hyperamylasemia, 75 patients undergoing cardiopulmonary bypass (CPB) were studied from March 1989 to January 1990. There were 49 males and 26 females. Among them, 27 had congenital heart disease, 30 had valvular disease, and 18 had coronary artery disease. There were 27 patients with at least one elevated serum amylase sample after operation. Thus, the overall incidence of hyperamylasemia was 36%. As compared with the preoperative data (1.3%), there was a statistically significant difference in the occurrence of hyperamylasemia (p less than 0.05). Three patients had overt clinical pancreatitis postoperatively. There was no positive correlation between the serum amylase level and the occurrence of pancreatitis (p greater than 0.05). Forty-two cases had a significant elevation of the amylase creatinine clearance ratio (ACCR) after CPB. However, there was no significant difference between the groups with pulsatile and nonpulsatile CPB (p greater than 0.05). Three patients (4%) died in our series. The causes of death were heart failure in two and fulminant pancreatitis associated with low cardiac output in one. Although our experience in dealing with pancreatitis improved survival, mortality was still high (33.3%) in our series. Nevertheless, there was no apparent correlation between mortality and postbypass hyperamylasemia (p greater than 0.05). Logistic regression analysis was used to analyze the risk factors of the occurrence of hyperamylasemia, and the analysis revealed that patients with coronary artery disease were susceptible to postbypass hyperamylasemia. Our studies indicate that the use of total serum amylase or ACCR to monitor for the occurrence of pancreatitis in postbypass patients is inadequate.(ABSTRACT TRUNCATED AT 250 WORDS)

Amylases↗

PubMed1992

Health care use by human immunodeficiency virus-infected students at a California student health service.

We report characteristics of 16 college students with human immunodeficiency virus (HIV) infection but without the acquired immunodeficiency syndrome who received care at a student health center at a major university in California. Sociodemographic and clinical data and medical expenditures were obtained retrospectively from medical charts and computerized billing records. All 16 students were men who had sex with men, and 3 had also used intravenous drugs. Dermatologic conditions, upper respiratory tract infections, gastrointestinal conditions, anemia, lymphadenopathy, sexually transmitted diseases, and ophthalmologic conditions were more frequent among HIV-infected students than among the general student population using the health center. On average, HIV-infected students visited the student health service about 3 times more often and incurred charges about 10 times higher than the general population of students visiting the health center. Student health centers, which have been at the forefront of developing strategies for HIV prevention, education, and counseling, must also develop treatment programs for HIV-infected students.

Adult↗

PubMed1991

Ion channel activities of cultured rat mesangial cells.

We used the patch-clamp technique to clarify the nature of ion channels in renal mesangial cells in culture. In the cell-attached mode most patches were silent in the absence of agonists. In some patches a 25-pS nonselective channel was observed. This 25-pS cation channel was consistently observed in inside-out patches, and it was activated by intracellular Ca2+. Excised patch experiments also revealed the existence of a 40-pS K+ channel, which was activated by intracellular Ca2+. This 40-pS K+ channel was observed infrequently in the cell-attached mode. The activities of both channels were increased by arginine vasopressin or angiotensin II, resulting from an increase in intracellular Ca2+ concentration.

Angiotensin II↗

PubMed1991

Concomitant occurrence of subchondral cyst and ruptured anterior crucial ligament at knee joint: new findings by MRI.

The magnetic resonance imaging (MRI) in 4 cases of subchondral cyst at the knee joint region, were acquired from a 1.5 Tesla imager. We found a high incidence of concomitant occurrence of subchondral cysts with a ruptured anterior cruciate ligament (ACL) in all of these cases. The 2 men and 2 women, had an average age of 35. Clinically, they complained of dull knee pain and mild instability. Conventional radiography detected subchondral cysts in 3 of them, while MRI disclosed that all of the subchondral cysts were at the tibial plateau, close to the intercondyloid eminence. To date, MRI is the only imaging modality which can depict the concomitant occurrence of a subchondral cyst and a ruptured anterior cruciate ligament at the knee joint. Whether these subchondral cysts were the consequences of the ruptured anterior cruciate ligaments as one of the causes in addition to synovial fluid intrusion and bony contusion, need further clinical observation and investigation.

Adult↗

PubMed1991

Surgical treatment of thoracoabdominal aortic aneurysm with graft inclusion technique.

Two male patients with huge thoracoabdominal aortic aneurysms were treated surgically at the National Taiwan University Hospital (NTUH) during the last 6 years. Case 1 was 70 years old with a case of malignant lymphoma. A huge thoracoabdominal aortic aneurysm was found which ruptured suddenly during the course of chemotherapy for malignant lymphoma. An emergency operation was performed because the patient suffered from profound shock. Case 2 was 34 years old and was referred to our hospital with a huge pulsating mass over his abdomen and progressive dysphagia. Both had atherosclerosis, thought to be the underlying etiology. The surgical technique we employed was the graft inclusion technique with major branch vessel reattachment to the side holes of the graft. Postoperative surgical results were excellent. Neither spinal cord complications nor visceral organ failure was found in either case. Case 1 unfortunately died 3 months after surgery because of advanced lymphoma with many organs being involved and upper GI bleeding. Case 2 is doing well and being followed up at our OPD at present.

Adult↗