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Biomedical subjects

T H Chan

Publications and source records attributed to T H Chan.

At least 37 records · Page 2Linked to original sources
PubMed1993

Coping process theory: a tool to reduce stress and cardiovascular disease.

1. Associations exist between stress and cardiovascular disease. This article presents the coping process theory as a possible strategy to reduce the incidence of cardiovascular disease. 2. The occurrence of coronary heart disease may be reduced by using the coping process to manage stress in the workplace. If the disease is present, coping with the stress of having the disorder diminishes its recurrence. 3. Social support is a valuable coping resource; its association with cardiovascular disease is demonstrated.

Adaptation, Psychological↗
PubMed1985

Adenosine deaminase binding protein, a new diagnostic marker for kidney disease.

This enzyme immunoassay detects adenosine deaminase binding protein (ABP), a glycoprotein that is shed from the brush border of the proximal tubule in kidney damage. Two monoclonal antibodies, URO-4 and URO-4a, each react with different epitopes on ABP and are used as the "sandwich" pair of antibodies. A linear standard curve can be generated by using partly purified ABP isolated from the urine of patients with kidney disease. Release of ABP into the urine appears to reflect the severity of the insult to the nephron. Therefore, measurement of ABP in urine may help distinguish between tubular disease and glomerular disease and indicate renal allograft rejection in renal-transplant patients.

Antibodies, Monoclonal↗
PubMed1977

The isolation and further characterization of the bilirubin tetrapyrroles in bile-containing human duodenal juice and dog gall-bladder bile.

Bilirubin and its conjugates were extracted from either dog gall-bladder bile or bile-containing human duodenal juice into chloroform containing 10mm-tetraheptylammonium chloride. The intact bilirubin tetrapyrroles were then separated by t.l.c. Structural elucidation was made after coupling of the individual pigments with diazonium salts. Four azopigments were detected: azopigment alpha(o) or dipyrrolic azobilirubin; azopigment delta or dipyrrolic azobilirubin monoglucuronide; azopigment alpha(3) or dipyrrolic azobilirubin monoglucoside; and, from dog gall-bladder bile, azopigment alpha(2). The last conjugate required further verification of its structure. After methanolysis, it was shown by combined g.l.c.-mass spectrometry to contain xylose in a 1:1 molar ratio with the azopigments of bilirubin. Human bile contained 86% bilirubin diglucuronide, 7% bilirubin monoglucuronide monoglucoside diester, 4% bilirubin monoglucuronide and 3% bilirubin. Dog gall-bladder bile had a considerably different composition; it contained 47% bilirubin diglucuronide, 40% bilirubin monoglucuronide monoglucoside diester, 8% bilirubin monoglucuronide, 4% bilirubin diglucoside, 1-2% bilirubin and traces of conjugates containing xylose. The total bilirubin content and proportions of the conjugates did not change in bile that was frozen and stored at -20 degrees C under N(2), whereas in the chloroform/tetraheptylammonium chloride extract, similarly stored, total pigment was slowly lost and the diglucuronide conjugate converted into the monoglucuronide.

Animals↗
PubMed1975

Biologically active substances in oak gall extracts. Part 1: Isolation and chemical identification of a substance exerting antihistamine-like activity (KC-18).

The previously reported antihistamine-like activity of partially purified oak gall extracts has been confirmed. Isolation of the active principle was achieved through the use of organic solvent extractions and column chromatographic (Sephadex LH-20 and silica gel) procedures. Preliminary investigation on the structure of this chemically pure substance using mass spectrometry, thin layer chromatography, base hydrolysis and electrophoresis indicated that it is most probably an ester of piperonylic acid. KC-18, given intraperitoneally in doses of 4 mg/kg to guinea pigs 5 hours prior to an exposure to a 0.15 per cent histamine aerosol, significantly reduced the bronchoconstrictor effect of histamine.

Animals↗
PubMed1974

The isolation of an azobilirubin beta-D-monoglucoside from dog gall-bladder bile.

An ethyl anthranilate azopigment of bilirubin conjugated to beta-d-monoglucoside was isolated from dog gall-bladder bile. Glucose was cleaved from the azopigment by treatment with beta-glucosidase and beta-glucuronidase. Mild alkaline hydrolysis of the compound by sodium methoxide yielded two kinds of compounds, water-soluble and organic-soluble. The former were shown, by enzymic analysis, t.l.c., nuclear magnetic resonance, and combined g.l.c. and mass spectrometry, to contain glucose. No evidence was obtained from these data that a disaccharide was present in this fraction. The organic-soluble compounds formed during this methanolysis were shown, by t.l.c. and mass spectrometry, to be the isomeric dipyrrole azopigments of bilirubin. These findings contribute further evidence to the controversy surrounding the nature of conjugated bilirubin.

Animals↗
PubMed1973

Hypertensive action of 18-hydroxydeoxycorticosterone.

18-Hydroxydeoxycorticosterone is an adrenal steroid hormone causing salt and water retention and is secreted in greatly increased amounts in response to the pituitary hormone adrenocorticotropic hormone. Its production is abnormally high in some forms of hypertension in man and rat. Direct proof that 18-hydroxydeoxycorticosterone is capable of causing hypertension is present. Daily subcutaneous injections of 200 micrograms, a low physiological dose, significantly increase the blood pressure of unilaterally nephrectomized saline-treated rats after 2 weeks. This strengthens the hypothesis that 18-hydroxydeoxycorticosterone contributes to the etiology of hypertension, possibly by a mechanism involving stressinduced release of adrenocorticotropic hormone.

Adrenocorticotropic Hormone↗