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J Ng

Publications and source records attributed to J Ng.

148 records · Page 9Linked to original sources
PubMedDate not supplied

HLA-B alleles associated with the B15 serologically defined antigens.

Cells expressing HLA molecules in the B15 family were identified by serologic typing in routine testing of volunteer donors of various ethnic backgrounds for a bone marrow registry. DNA sequencing was used to identify HLA-B15 alleles associated with each serologic type and to examine the diversity within the B15 antigen family. Alleles which appeared predominantly in each B15 serologic cluster included: B15 with no defined serologic subdivision (B*1501), B62 (B*1501), B63 (B*1516, B*1517), B75 (B*1502, B*1521), and B76/77 (B*1513). Other B*15 alleles were also found associated with the serotypes and some of these alleles (e.g., B*1501 and B*1516) were found in two or more serologic clusters illustrating the complexity of this family. The B15 unsplit and B75 groups were the most complex exhibiting 16 and 7 alleles, respectively, within each serotype. Five new B*15 alleles (B*1530, B*1531, B*1533, B*1534, B*1535) and 5 other new HLA-B alleles (B*38022, B*3910, B*4010, B*51012, and B*5108) were also identified.

Alleles↗
PubMedDate not supplied

SI units and the clinical practice of infectious diseases: application to the usage of antimicrobial agents.

Over the next few years, le Système international d'Unités or SI units may replace the presently used metric system in reporting laboratory data. The change to SI units will likely result in some confusion among clinicians who are not well versed in the new system. Application of SI units to the clinical practice of infectious diseases is discussed, including changes in drug dosages, serum drug levels, and minimum inhibitory concentrations. A table is presented to facilitate conversion of metric units to SI units and vice versa.

Anti-Bacterial Agents↗
PubMedDate not supplied

Mechanism of the antiproliferative action of leflunomide. A77 1726, the active metabolite of leflunomide, does not block T-cell receptor-mediated signal transduction but its antiproliferative effects are antagonized by pyrimidine nucleosides.

BACKGROUND: Leflunomide, a novel immunosuppressive drug, prolongs experimental graft survival effectively and has been well tolerated in patients with rheumatoid arthritis. A77 1726, the active metabolite of leflunomide, inhibits lymphocyte proliferation in vitro. This study was conducted in Jurkat T cells to investigate the effects of A77 1726 on signal transduction pathways initiated by ligands of the T-cell receptor CD3 complex and to evaluate the effects of A77 1726 on nucleotide biosynthesis. METHODS: Tritiated thymidine incorporation and cell counts quantitated cell proliferation. Spectrofluorescence of Indo/AM dye measured intracellular Ca2+ mobilization. A luciferase assay quantitated interleukin-2 gene promoter activity in stimulated cells transfected with an interleukin-2 promoter-luciferase gene construct. Pyrimidine and purine nucleosides were used to assess antagonism of the antiproliferative activity of A77 1726. RESULTS: (1) A77 1726 dose-dependently inhibited the proliferation of Jurkat T cells (inhibitory concentration of 50% = 6 mumol/L); (2) A77 1726 did not decrease mobilization of intracellular Ca2+ stimulated by phytohemagglutinin or anti-CD3 monoclonal antibody; (3) A77 1726 did not inhibit interleukin-2 gene promoter activity in cells stimulated with ionomycin plus phorbol myristate acetate; (4) inhibition of cell proliferation by A77 1726 was antagonized by addition of uridine, cytidine, or 2(+)-deoxycytidine; (5) addition of uridine 24 hours after treatment with A77 1726 antagonized inhibition of proliferation; (6) A77 1726 was not antagonized by 2'-deoxyuridine, thymidine, adenosine, or guanosine. CONCLUSIONS: (1) A77 1726 inhibited Jurkat T-cell proliferation without inhibiting T-cell receptor-mediated signal transduction events, including tyrosine kinase-dependent intracellular Ca2+ mobilization and activation of the interleukin-2 gene promoter; (2) the antiproliferative effects of A77 1726 on Jurkat T cells are primarily due to interruption of de novo pyrimidine nucleotide biosynthesis. These data provide evidence for a novel in vitro mechanism of the antiproliferative action of this immunosuppressant.

Aniline Compounds↗