Search PubMed⌕ Search

Biomedical subjects

Y S Liu

Publications and source records attributed to Y S Liu.

At least 55 records · Page 3Linked to original sources
PubMed1991

[Histopathological and ultrastructural changes in the liver and their pathogenesis in burns of rabbits].

48 health male rabbits were randomly divided into two groups: a napalm burn group and a healthy control group. The total area of burn was 30% TBSA full-thickness burn. Blood and liver tissue specimens were taken at 2, 6, 12, 24, 48, 72 and 168 hours postburn for quantitative analysis of serum enzymes, protein and histopathological, subcellular examination of the liver. Results indicated that hepatic pathological changes were characterized by an early onset, severity in extent, wide distribution and diversified morphology. Basic pathological changes in the liver included: (1) degeneration and necrosis of the hepatic cells and their transitional changes; (2) infiltration of inflammatory cells in parenchyma and interstices; (3) proliferation and swelling of Kupffer cells with active phagocytosis and subsequent degeneration. The overall course of changes observed in the liver specimens was divided into four phases: (1) congestive and anoxia phase, (2) inflammation phase, (3) degeneration and necrosis phase, (4) repair phase. The causes and pathogenesis of the four phases were analysed and discussed. Three possibilities of their pathogenesis were suggested according to morphological features and the course of the development of focal intracytoplasmic degeneration (FCD) and lytic necrosis (FCLY).

Alanine Transaminase↗
PubMed1991

[Synthesis and cerebral vasodilating effects of tetrahydro-pyrido [1,2-a] indole derivatives].

A series of 2-substituted-6-oxo-10-[2-(N-substituted)carbamoyl]ethyl- 6,7,8,9-tetrahydro-pyrido[1,2-a]indole compounds were synthesized for studying the relation between structures and cerebrovascular activities. The structures of compounds synthesized were confirmed by means of 1HNMR, MS, IR, UV and elemental analysis. Preliminary pharmacological experiments showed that all these new compounds were effective for cerebral vasodilation. Compound I7 was the best of all. The beta-diethylaminoethylamine moiety seems to be better than beta-dimethylaminoethylamine.

Animals↗
PubMed1990

Calmodulin-binding proteins of Saccharomyces cerevisiae.

The subcellular distribution of calmodulin-binding proteins in the soluble, plasma membrane, and nuclear fractions of Saccharomyces cerevisiae was analyzed with a gel binding assay using 125I-labeled calmodulin. Over 20 binding proteins were detected. The calmodulin-binding protein profiles were markedly different among the fractions. Calmodulin-binding proteins were most abundant in the nuclear fraction, followed by the membrane fraction and the soluble fraction in decreasing order. The amounts of certain calmodulin-binding proteins increased after treatment with alpha-mating factor.

Calmodulin↗
PubMed1989

Heterogeneity of the Ro/SSA antigen. Different molecular forms in lymphocytes and red blood cells.

Ro(SSA) is an intracellular ribonucleoprotein against which autoantibodies are found in a portion of patients with Sjögren's syndrome and systemic lupus erythematosus. A form of Ro(SSA) is described in red blood cells that shares a line of identity with purified Ro(SSA) from bovine spleen and human lymphocytes in counterimmunoelectrophoresis, but has different molecular properties. Ro(SSA) from red blood cells exists in association with only two small RNAs as opposed to four in other cell types, as determined by RNA extraction of protein A-assisted immunoprecipitates. In addition to the common 60-kD Ro(SSA) protein, Western blot analysis revealed an additional 52-kD protein in lymphocytes and a 54-kD protein in red blood cells. The 60-kD form of Ro(SSA) in red cells was found to be antigenically distinct from that in the lymphocyte, because sera were identified that bound each exclusively. Finally, a rabbit antibovine Ro(SSA) serum distinguished red cell from lymphocyte Ro(SSA). These results suggest two distinctive populations of Ro(SSA) proteins and distributions of Ro(SSA) RNAs in the lymphocyte and red blood cell.

Animals↗
PubMed1988

A quantitative nitrocellulose enzyme immunoassay and its application to the screening of hybridomas for the detection of uncharacterized tumor-associated antigens in sera of cancer patients.

An enzyme-linked immunosorbent assay on nitrocellulose based microtiter plates for the detection of uncharacterized tumor associated antigens in squamous cell carcinoma and adenocarcinoma cancer patients' sera is described. Nitrocellulose microtiter plates are more sensitive than the plastic plates of polystyrene and polyvinyl chloride for the detection of antigens in serum. Monoclonal antibodies were selected for their net reactivities toward cancer patients' sera as compared to normal sera. Sera from benign liver and kidney disease patients and activated human peripheral blood leukocyte supernatant were used to reduce potential false positives toward inflammatory and benign diseases. Using this system, fourteen antibodies were selected out of over eight hundred antibodies for their potential serodiagnostic application.

Adenocarcinoma↗
PubMed1987

Reactivity of monoclonal antibody 17.13. with human squamous cell carcinoma and its application to tumor diagnosis.

Monoclonal antibody 17.13., derived from a fusion of splenocytes of a BALB/c mouse immunized with a surgically resected poorly differentiated human laryngeal recurrent squamous cell carcinoma (SCC) with mouse Sp2/0 cells, is an IgM-K which recognizes a cytoplasmic component of basal cells. Tissue sections of malignant and normal squamous epithelium, tumors of nonsquamous origin, and normal and malignant cytological specimens were tested with an immunoperoxidase assay. Seventy-nine of 81 (98%) SCC of the head and neck, 26 of 26 (100%) SCC of the cervical and female gynecological tract, 29 of 30 (97%) SCC of the lung, 19 of 19 (100%) SCC of the oral cavity, and 17 of 17 (100%) SCC-involved neck lymph nodes reacted strongly. Various carcinomas from breast, colon, ovary, and others were unreactive. In normal squamous epithelial tissues, monoclonal antibody 17.13. reacts only with basal cells but not the cells above the basal layers. Normal tissues from heart, liver, spleen, kidney, bladder, colon, ovary, stomach, pancreas, breast, lung, prostate, thyroid, and lymph nodes were unreactive with the exception of myoepithelial cells. Monoclonal antibody 17.13. may be useful in the diagnosis and management of SCC.

Animals↗
PubMed1985

A monoclonal-antibody enzyme immunoassay for detection of hepatitis B surface antigen with use of a biotin-avidin system.

In this solid-phase two-site enzyme immunoassay for hepatitis B surface antigen (HBsAg), three monoclonal anti-HBs are used: 5D3 (IgM) is immobilized on plastic beads; 5C3 (IgG2a) and 5C 11 (IgG1), labeled with biotin, are used as the first conjugate. Horseradish peroxidase covalently linked to avidin is the second conjugate. First, serum or plasma is incubated with the antibody-coated bead and biotin-labeled antibodies, simultaneously, at 45 degrees C for 1 h ("stat" procedure), 3 h ("standard" procedure), or 18 h ("overnight" procedure), during which HBsAg forms a complex with the solid-phase antibody and the biotinylated antibodies. The enzyme-conjugated avidin is then bound to the biotin on the antigen-antibody complex at 45 degrees C for 15 min ("stat") or 30 min (standard and overnight procedures). The beads are incubated with enzyme-substrate solution (H2O2 and o-phenylenediamine). Color developed is measured at 492 nm. All procedures satisfied third-generation HBsAg tests required by the FDA Office of Biologics, being sensitive both to ad and ay subtypes in subnanogram amounts. The assay is reactive with adw2, adw4, adr, ayw2, ayw3, and ayr subtypes and can detect viral determinants in HBsAg-anti-HBs immune complex form. Thus it provides a sensitive, simple, and reproducible alternative to radioimmunoassay.

Antibodies, Monoclonal↗
PubMed1985

A more specific, simpler radioimmunoassay for carcinoembryonic antigen, with use of monoclonal antibodies.

A solid-phase, two-site monoclonal antibody radioimmunoassay for carcinoembryonic antigen in serum or plasma has been developed. Two monoclonal antibodies are used: 3d6, which is immobilized on polystyrene beads, reacts with high-molecular-mass CEA; the other, C4, with apparently restricted reactivity toward gastrointestinal tract and mammary carcinomas, is labeled with 125I. The assay consists of incubating 0.2 mL of serum both with 3d6-coated beads and 125I-labeled C4 at room temperature for 18 h. The CEA standard is calibrated against WHO international standard (73/601). Advantages of this assay include: (a) no heat or acid pre-treatment of samples; (b) linear response over a wider functional range, 0 to 150 micrograms/L, requiring fewer calibration points; and (c) no interference by glycosaminoglycans. Average inter- and intra-assay reproducibilities (CVs) are less than 10%; analytical recovery of CEA was 94 to 107%. CEA of less than 0.5 micrograms/L can be detected. The mean concentration of CEA in serum from healthy individuals is 0.97 (SD 1.18) micrograms/L; only 3% of the sera tested had concentrations greater than 3.0 micrograms/L. On comparing this assay with a polyclonal RIA, we found similar assay sensitivity for colorectal carcinoma but fewer false-positive results for sera from patients with benign liver and bowel diseases.

Adult↗
PubMed1982

Bluetongue virus: comparative evaluation of enzyme-linked immunosorbent assay, immunodiffusion, and serum neutralization for detection of viral antibodies.

Comparative studies on the detection of bovine serum immunoglobulin G antibodies to bluetongue virus with an enzyme-linked immunosorbent assay, an immunodiffusion method, and a serum neutralization assay demonstrated complete concordance between the enzyme-linked immunosorbent assay and the serum neutralization assay results. However, the immunodiffusion method failed to detect bluetongue virus antibody in a substantial number of sera found to possess bluetongue virus immunoglobulin G with the enzyme-linked immunosorbent assay.

Animals↗
PubMed1979

Primary structure of a human IgA1 immunoglobulin. I. Isolation, composition, and amino acid sequence of the chymotryptic peptides.

As the initial phase of the determination of the complete covalent structure of a human immunoglobulin A, 52 chymotryptic peptides, ranging in length from 2 to 37 residues, were isolated and characterized from the reduced and carboxymethylated alpha1 heavy chain of the myeloma IgA protein Bur. The peptides were subjected to sequence analysis by the dansylation technique, manual and automatic Edman degradation, and carboxypeptidase digestion. The results, in conjunction with the data on the tryptic and thermolysin peptides and the cyanogen bromide fragments reported in the accompanying papers, established the complete primary structure of a human IgA chain.

Amino Acid Sequence↗
PubMed1979

Primary structure of a human IgA1 immunoglobulin. IV. Streptococcal IgA1 protease, digestion, Fab and Fc fragments, and the complete amino acid sequence of the alpha 1 heavy chain.

In order to establish the complete amino acid sequence of the human IgA alpha1 chain Bur, IgA1 protease from Streptococcus sanguis was employed to generate Fabalpha and Fcalpha fragments in the final stage of this investigation. Cyanogen bromide cleavage of the Fabalpha fragment followed by reduction and aminoethylation produced the Fd' fragment (residues 84 to 227); this contains part of the variable region (VR), the whole first constant domain (Calpha1), and part of the hinge region of this heavy chain. The tryptic peptides of the Fd' fragment were isolated, characterized, and sequenced. The results together with the data in the preceding papers on chymotryptic, tryptic, and thermolysin peptides permitted the complete amino acid sequence of the human IgA alpha1 chain to be established.

Amino Acid Sequence↗
PubMed1979

Primary structure of a human IgA1 immunoglobulin. II. Isolation, composition, and amino acid sequence of the tryptic peptides of the whole alpha1 chain and its cyanogen bromide fragments.

As part of the strategy for determining the covalent structure of a human IgA1 molecule (Bur), a tryptic digest was prepared of the reduced and carboxymethylated alpha1 heavy chain. In addition to the main experiment, tryptic peptides were prepared from the succinylated aminoethylated alpha1 chain and from fragments obtained by CNBr scission of the alpha1 chain. Complete recovery of the peptides was impeded by the large size of some of the tryptic peptides and of the principal CNBr fragment, and difficulty in separating other glycopeptides. Twenty-eight tryptic peptides of the reduced and carboxymethylated alpha1 chain were purified and sequenced, accounting for more than 300 residues. Additional information was obtained by sequence analysis of trypudies described in this series of papers contributed to the complete sequence analysis of the alpha1 chain.

Amino Acid Sequence↗
PubMed1979

Primary structure of a human IgA1 immunoglobulin. III. Isolation, composition, and amino acid sequence of the thermolysin peptides.

As part of the strategy for determination of the complete covalent structure of a human IgA immunoglobulin, 66 peptides were isolated from a thermolysin digest of reduced and carboxymethylated IgA alpha1 chain Bur and were purified. They range in length from 2 to 24 residues. Some of the peptides have been characterized and sequenced in order to supply needed information that was not obtained from the chymotryptic and tryptic peptides. These thermolysin peptides provide much necessary data to produce a rigorous proof for the primary structure of the human alpha1 chain. The remaining peptides from the thermolysin digest whose amino acid composition and NH2-terminal residues were sufficient to identify them unequivocally have also been assigned in the structure. They supply additional information that helps remove ambiguity in the structure, and they provide useful data about the profile of the peptide bonds that are susceptible to thermolysin digestion.

Amino Acid Sequence↗
PubMed1977

Location and structural significance of the oligosaccharides in human Ig-A1 and IgA2 immunoglobulins.

The location, number, and kinds of oligosaccharides in human IgA1 and IgA2 immunoglobulins have been determined by amino acid sequence analysis of the alpha heavy chains. Both A2m allotypes of the alpha2 chain of IgA2 have two GlcN oligosaccharides that are absent in the alpha1 chain, but they lack GalN. The A2m(2) allotype has a fifth GlcN oligosaccharide. The alpha chains of IgA proteins also have subclass-specific and allotype-specific differences in amino acid sequence. Although other classes of human immunoglobulins differ in the number and kind of oligosaccharides, the sites are often homologous and are related to the immunoglobulin domain structure. Evolutionary preservation of the tripeptide acceptor sequence for GlcN probably indicates both a structural and biological role for carbohydrate.

Amino Acid Sequence↗