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S K Law

Publications and source records attributed to S K Law.

5 recordsLinked to original sources
PubMed1979

Action of the C3b-inactivator on the cell-bound C3b.

The action of C3bINA and beta 1H on cell-bound C3b is described in this paper. The alpha-polypeptide of C3b that binds covalently to cell surfaces is cleaved by the C3bINA and beta 1H into two fragments: one of 60,000 (C3b alpha-60) and another of 40,000 (C3b alpha-40) daltons. The beta-chain of C3b is unaffected by the C3bINA and beta 1H. The three polypeptides, C3b alpha-60, C3b alpha-40, and C3 beta, are held together as a single unit by disulfide bonds. This unit, referred to as C3b' is covalently bound to cell surfaces via the C3b alpha-60 polypeptide. The conversion of C3b to C3b' by C3bINA and beta 1H abolishes the ability of the C3b-bearing cells to adhere to human erythrocytes as well as the ability to form, on the cell surface, the B, D, and properdin-dependent amplification C3-convertase. However, the agglutinability of the cells with either anti-C3c or anti-C3d is not affected. Treatment of the C3b'-bearing cells with trypsin releases fragments of C3b' into solution, leaving a polypeptide of 32,000 daltons covalently linked to the membrane. Since the trypsinized cells are agglutinable by anti-C3d but not by anti-C3c, the 32,000 dalton polypeptide appears to correspond antigenically to C3d.

Animals↗
PubMed1978

Urban-rural differences in student mental health: the Hong Kong scene.

Student mental health of Hong Kong urban and rural fifth formers and sixth-formers was assessed by examining their scores obtained from the General Health Questionnaire twice administered. The first administration was done soon after commencement of a school term and served as a baseline measure, and the second was done six weeks before the fifth-formers took an important public examination, a significantly stressful event. The results indicated that all groups of fifth-formers showed an increase in mean scores, reaching statistical significance only in urban boys and rural girls. The latter finding was used to explain urban-rural differences in mean scores. The significance of severe examination distress and its possible late psychiatric sequelae remained unanswered.

Achievement↗
PubMed1977

Interaction between the third complement protein and cell surface macromolecules.

The activated form of the third complement protein, C3b, forms a stable complex with components of plasma membranes and particulate entities such as zymosan. The complex resists the action of detergents and protein denaturants as well as extremes of temperature, salt concentration, and pH. It can, however, be broken by exposure to hydroxylamine or by ammonolysis followed by incubation with sodium dodecyl sulfate. Thus, the complex appears to result from a hydrophobic interaction as well as a bond susceptible to nucleophilic attack.

Complement C3↗