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Biomedical subjects

J H Chang

Publications and source records attributed to J H Chang.

13 recordsLinked to original sources
PubMed1992

Possible mechanism of immunosuppressive effect of scoparone (6,7-dimethoxycoumarin).

The possible mechanism of the immunosuppressive effect of scoparone (6,7-dimethoxycoumarin) was investigated. Human peripheral blood mononuclear cells (10(6) cells/ml) were stimulated with 0.25% phytohemagglutinin (PHA) and the proliferative response was determined from the uptake of tritiated thymidine. Scoparone (10(-6) to 3 x 10(-4) M) reduced the proliferative response in a dose-dependent manner. The proliferative response of mononuclear cells to mixed lymphocyte reaction was also reduced by scoparone (10(-5) to 10(-4) M). Interleukin-1, interleukin-2 production and interleukin-2 receptor expression were all reduced in the presence of scoparone. Scoparone (10 and 30 microM) significantly reduced the suppression elicited by the diabetogenic drug, alloxan (10 mM). The suppressive activity of scoparone was significantly reduced by quinacrine (a phospholipase A2 inhibitor), indomethacin (a cyclooxygenase inhibitor) and nordihydroguaiaretic acid (a lipoxygenase inhibitor). The levels of prostaglandin E2, prostaglandin F2 alpha, leukotriene B4 and 2,3-dinor-thromboxane B2 in culture medium of PHA-stimulated mononuclear cells, measured with an enzyme immunoassay, were elevated by scoparone treatment. We compared the effect of scoparone on the mononuclear cell response to genistein, a specific inhibitor of protein tyrosine kinase and demonstrated the non-additivity and cross-desensitization of the two compounds. Our results suggest that the immunosuppressive effect of scoparone may be exerted in part through inhibition of protein tyrosine kinase and release of arachidonic acid metabolites.

Alloxan↗
PubMed1992

Immunosuppressive effect of emodin, a free radical generator.

The possible mechanism of immunosuppressive effect of emodin (1,3,8-trihydroxy-6-methylanthraquinone) was investigated in this study. Human mononuclear cells (10(6) cells/ml) were stimulated with 0.25% phytohemagglutinin for 24, 48 and 72 h, and the proliferative response was determined by the uptake of tritiated thymidine. In the presence of emodin (10(-6) to 3 x 10(-5) M), the proliferative response was reduced in a dose-dependent manner. Emodin (3 x 10(-7) to 3 x 10(-5) M) also dose dependently reduced the proliferative response to mixed lymphocyte reaction. After 72 h exposure to emodin (10 microM), interleukin-1 (IL-1), interleukin-2 (IL-2) production and IL-2 receptor expression were all reduced. The structure-activity relationship of emodin and 10 other anthraquione derivatives indicates that the free hydroxyl group at the beta-position of the anthraquinone nucleus plays an important role in the immunosuppressive effect. The suppressive activity of emodin was significantly inhibited by catalase (a scavenger of hydrogen peroxide), but little affected by superoxide dismutase (a scavenger of superoxide radical) and mannitol (a scavenger of hydroxyl radical). Methylene blue and hemoglobin, guanylate cyclase inhibitors, did not significantly affect the suppressive activity of emodin. Nordihydroguaiaretic acid (a lipoxygenase inhibitor) significantly potentiated the suppressive activity whereas quinacrine (a phospholipase A2 inhibitor) and indomethacin (a cyclooxygenase inhibitor) did not significantly affect it. The results suggest that the immunosuppressive effect of emodin may be partly mediated through hydrogen peroxide generated from semiquinone and regulated by arachidonic acid metabolites or byproducts.

Anthraquinones↗
PubMed1992

Antibodies of different immunoglobulin isotypes in serum and bile of patients with clonorchiasis.

Specimens of serum and bile from patients were assayed by an enzyme-linked immunosorbent assay to reveal antibodies specific to antigens from adult Clonorchis sinensis. Antibodies of the IgG isotype showed the greatest elevation during infection (Student's t-test, P < 0.001), whereas serum IgA and IgE and secretory IgA in bile were moderately elevated (P < 0.05). Major differences in the distribution of antibodies among the IgG subclasses were observed between patients who were and those who were not infected. IgG4 antibody levels were elevated in the serum and bile of infected patients, and there were significant correlations between the levels of IgG and IgG4 antibodies and the intensity of infection.

Adult↗
PubMed1992

Fatty acid composition and fatty acid elongase and stearoyl-CoA desaturase activities in tissues of steers fed high oleate sunflower seed.

The effects of a high oleate sunflower seed diet on tissue composition and on fatty acid elongation and desaturation enzyme activities were investigated. Three Simmental calves were fed a standard corn-based diet (2.6% fat); three others were fed the corn-based diet containing 20% high oleate sunflower seed (10.4% fat). Blood samples and perianal adipose tissue samples were obtained at 7, 90 and 180 d on trial. Samples of liver, longissimus dorsi muscle and intestinal mucosa were obtained at the termination of the experiment (195 d on trial). Plasma oleate was higher (P < 0.05) in the cattle fed the sunflower seed, and oleate, myristate (P < 0.05) and stearate (P < 0.06) were elevated in perianal adipose tissue in response to the greater lipid content of the dietary sunflower seed. Dietary sunflower seed decreased the concentration of stearate (P < 0.05) in liver. The high oleate diet significantly (P < 0.05) increased the activity of stearoyl-CoA desaturase activity in muscle, and numerical increases in desaturase activity were observed in liver, adipose and small intestine samples. Elongase activity was unaffected by diet. Because stearate is the primary fatty acid available for absorption in ruminants, elevated oleate in plasma and depressed stearate in liver of cattle fed sunflower seed may have reflected an adaptive response of stearoyl-CoA desaturase in their tissues.

Acetyltransferases↗
PubMed1992

Tuberculosis of the ribs: a recurrent attack of rib caries.

Rib tuberculosis is an extremely rare condition with the incidence not exceeding 3 percent of all skeletal tuberculosis. The authors experienced a recalcitrant case of pulmonary tuberculosis accompanied by chest wall cold abscesses involving ribs recurring at a new site in approximately 10 months despite of medical and surgical treatment. The patient has twice taken thoracotomy for abscess drainage and during the second thoracotomy, a partial resection of involved ribs was performed.

Adolescent↗
PubMed1979

Acquired aganglionosis.

A documented case of acquired aganglionosis is presented in which transrectal biopsies taken 4 mo apart first showed the presence then subsequently the absence of ganglion cells. Colostomy followed by a Soave procedure was curative.

Colostomy↗
PubMed1979

Obstruction of the suprahepatic inferior vena cava as a complication of giant omphalocele repair.

Obstruction of the inferior vena cava with resultant Budd-Chiari syndrome after giant omphalocele repair has not previously been reported. Such a case is presented. We hypothesize the mechanism of this blockage to be posterior displacement of the inferior vena cava during reduction of the viscera and closure of the anterior abdominal wall, thereby creating angulation and mechanical blockage of the inferior vena cava at the diaphragmatic hiatus.

Budd-Chiari Syndrome↗
PubMed1977

Recognizing and referring neonatal surgical emergencies.

Ultimate survival of the neonate with a surgical emergency depends upon early recognition by the family physician, who may refer the infant to a pediatric surgical center. The family physician must prevent infectious and metabolic insults to the critically ill neonate while preparing him for safe and rapid transport to a specialty institution. In many cases, the final outcome is as often determined by the initial care received at the referring hospital and during transport as it is by the surgical procedures and postoperative management.

Abdominal Muscles↗
PubMed1977

Imperforate Anus: a five to thirty year follow-up perspective.

A twenty-five year experience with 284 patients with imperforate anus has been reviewed, with a 5 to 30 year assessment after surgical intervention. The following conclusions seem to be suggested by the study: 1. There was a 20% mortality overall, with the greatest number of these occurring in the Type III high lesions. Eighty per cent of the deaths were unrelated to imperforate anus and resulted from associated anomalies. 2. Eighty-eight per cent of the overall series achieved socially acceptable continence. Four out of five poor results occurred in the Type III high lesions. 3. Functional results achieved in imperforate anus surgery seem more closely related to the anatomy presented to the surgeon than by his choice of operative procedure. 4. Continence is more slowly achieved in an imperforate anus patient than in a normal child. It is an evolutionary process which seems to improve with age, being especially influenced by the social motivation that comes with puberty. 5. An appreciable number of patients with poor musculature for continence remain clean by promptly heeding the defection signals, by avoiding laxative foods, and by enforced constipation. 6. Secondary surgery when the levator sling muscles have been missed or partially bypassed seems to improve continence in a high percentage of patients.

Adolescent↗
PubMed1976

Differentiation of mouse neuroblastoma cells in vitro and in vivo induced by cyclic adenosine monophosphate (cAMP).

The murine neuroblastoma appears to be a useful model for elucidating the mechanism of cellular differentiation. In tissue culture, MNB cells were induced to "irreversibly" differentiate into neuronal-like cells by DBcAMP alone or in combination with cAMP phosphodiesterase inhibitors: papaverine (Pap) and theophylline (Theo). Cells differentiated by DBcAMP, Pap, and Theo were no longer tumorgenic when reinoculated into animals of the host strain. In vivo, DBcAMP, Pap, and Theo caused a reduced tumor volume growth rate in animals with established tumors. Morphologically, this effect appears to be secondary to an arrest of cellular mitoses. Cells insensitive to these agents emerged after 3 to 4 days, and tumor growth accelerated to parallel the rate of the untreated tumors.

Adenosine Monophosphate↗