Search PubMed⌕ Search

Biomedical subjects

Z Liu

Publications and source records attributed to Z Liu.

At least 1,405 records · Page 78Linked to original sources
PubMed1984

Separation of four glucuronides in a single sample by high-pressure liquid chromatography and its use in the determination of UDP glucuronosyltransferase activity toward four aglycones.

A single-solvent, reverse-phase HPLC system that separates glucuronides has been developed, and its applicability to the separation of glucuronides of four substrates (1-naphthol, morphine, testosterone, and estrone), representative of different UDP-glucuronosyltransferase enzymes, has been demonstrated. The combined supernatants from four separate microsomal incubations from which the protein has been precipitated can be used directly for the quantitation of the glucuronides formed. Variations in the four enzyme activities, upon treatment of rats with microsomal enzyme-inducing agents, after liver trauma and in the Gunn strain of rats have been investigated.

Animals↗
PubMedDate not supplied

Identification of a W variant outbreak of Mycobacterium tuberculosis via population-based molecular epidemiology.

CONTEXT: Typing of Mycobacterium tuberculosis could provide a more sensitive means of identifying outbreaks than use of conventional surveillance techniques alone. Variants of the New York City W strain of M tuberculosis were identified in New Jersey. OBJECTIVE: To describe the spread of the W family of M tuberculosis strains in New Jersey identified by molecular typing and surveillance data. DESIGN: Population-based cross-sectional study. SETTING AND SUBJECTS: All incident culture-positive tuberculosis cases reported in New Jersey from January 1996 to September 1998, for which the W family was defined by insertion sequence (IS) IS6110 DNA fingerprinting, polymorphic GC-rich repetitive sequence (PGRS) typing, spacer oligotyping (spoligotyping), and variable number tandem repeat (VNTR) analysis. MAIN OUTCOME MEASURE: Identification and characterization of W family clones supplemented by surveillance data. RESULTS: Isolates from 1207 cases were analyzed, of which 68 isolates (6%) belonged to the W family based on IS6110 and spoligotype hybridization patterns. The IS6110 hybridization patterns or fingerprints revealed that43 patients (designated group A) shared a unique banding motif not present in other W family isolates. Strains collected from the remaining 25 patients (designated group B), while related to W, displayed a variety of IS6110 patterns and did not share this motif. The PGRS and VNTR typing confirmed the division of the W family into groups A and B and again showed group A strains to be closely related and group B strains to be more diverse. The demographic characteristics of individuals from groups A and B were specific and defined. Group A patients were more likely than group B patients to be US born (91 % vs 24%, P<.001), black (76% vs 16%, P<.001), human immunodeficiency virus positive (40% vs 0%, P = .007), and residents of urban northeast New Jersey counties (P<.001). Patients with group B strains were primarily non-US born, of Asian descent, and more dispersed throughout New Jersey. No outbreak had been detected using conventional surveillance alone. CONCLUSIONS: The implementation of multiple molecular techniques in conjunction with surveillance data enabled us to identify a previously undetected outbreak in a defined geographical setting. The outbreak isolates comprise members of a distinct branch of the W family phylogenetic lineage. The use of molecular strain typing provides a proactive approach that may be used to initiate, and not just augment, traditional surveillance outbreak investigations.

Adult↗
PubMedDate not supplied

Fine mapping of the antigen-antibody interaction of scFv215, a recombinant antibody inhibiting RNA polymerase II from Drosophila melanogaster.

A bacterially expressed single chain antibody (scFv215) directed against the largest subunit of drosophila RNA polymerase II was analysed. Structure and function of the antigen binding site in scFv215 were probed by chain shuffling and by site-specific mutagenesis. The entire variable region of either the heavy or light chain was replaced by an unrelated heavy or light chain. Both replacements resulted in a total loss of binding activity suggesting that the antigen binding site is contributed by both chains. The functional contributions of each complementarity determining region (CDR) were investigated by site specific mutagenesis of each CDR separately. Mutations in two of the CDRs, CDR1 of light chain and CDR2 of heavy chain, reduced the binding activity significantly. Each of the amino acids in these two CDRs was replaced individually by alanine (alanine walking). Seven amino acid substitutions in the two CDRs were found to reduce the binding activity by more than 50%. The data support a computer model of scFv215 which fits an epitope model based on a mutational analysis of the epitope suggesting an alpha-helical structure for the main contact area.

Alanine↗
PubMedDate not supplied

Cytochrome P-450 metabolic-intermediate complex formation from p-aminobenzoic acid esters and other arylamines.

Metabolism of a series of p-aminobenzoic acid esters by rat liver microsomal fractions resulted in the formation of cytochrome P-450 metabolic - intermediate complexes. With conditions that allowed complex formation to proceed to completion, about 20% of control rat cytochrome P-450 was sequestered as a complex. Phenobarbital, but not beta-naphthoflavone induced additional cytochrome P-450, which with specific esters could be complexed to about 60%. For other esters, the induced cytochrome maximally complexed to about 20%, as was seen in uninduced rats. The two groups of p-aminobenzoic acid esters could not be readily delineated by lipid/water partition coefficients or steric factors.

4-Aminobenzoic Acid↗
PubMedDate not supplied

Infectious tolerance mediated by CD8+ T-suppresor cells after UV-B-irradiated donor-specific transfusion and rat heart transplantation.

AIMS: CD8+CD28- human T-suppressor cells (Ts), which can be generated in vitro, act directly on APC rendering them tolerogenic to unprimed and primed CD4+ T cells. The aim of this study was to investigate the possibility that CD8+ T cells mediate the induction of tolerance in a heart transplantation model in rodents. MATERIALS AND METHODS: Blood from Lewis rats was UV-B-irradiated and transfused into ACI recipients on days -21, -14, and -7 before heart allograft transplantation on day 0. CD4(+) and CD8(+) T cells were positively selected from ACI rats, which had tolerated Lewis heart allografts for more than 100 days and were adoptively transferred to naive ACI rats pretreated (day -1) with gamma irradiation. These ACI rats underwent transplantation with Lewis hearts 24 hours after adoptive transfer of putative T-suppressor cells. RESULTS: Adoptive transfer of CD8(+) T cells from tolerant ACI to naive ACI rats significantly prolonged Lewis heart mean allograft survival time (MST +/- SD) to 69 +/- 13 days as compared with 15 +/- 1 and 14 +/- 1 days in animals adoptively transferred with CD4+ T cells or untreated controls, respectively (P < .001). Similarly, adoptive transfer of CD8(+) T cells from secondary ACI recipients to naive syngeneic animals also significantly prolonged survival of heart allografts to MST +/- SD of 72 +/- 4 for CD8(+) and 15 +/- 4 days for CD4(+) T cells (P < .001). CONCLUSIONS: These data demonstrate that allogeneic tolerance induced in ACI recipients by treatment with UV-B-irradiated blood from Lewis donors is mediated by CD8+ T-suppressor cells.

Adoptive Transfer↗