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D Y Liu

Publications and source records attributed to D Y Liu.

At least 109 records · Page 6Linked to original sources
PubMed1988

Evidence for an intracellular pool of a migration inhibitory factor-associated, activation antigen of human mononuclear phagocytes, Mo3e.

Mo3e is a protease-sensitive Ag (p75,50) selectively expressed by human monocytic cells stimulated in vitro by exposure to various activating factors including PMA. Here, we report the existence of a large intracellular pool of Mo3e Ag in addition to that expressed on the surface of activated U-937 cells. As detected by quantitative immunofluorescence analysis, permeabilization of unstimulated and PMA-stimulated U-937 cells revealed a latent pool of Mo3e Ag that was 75-fold and 9-fold greater, respectively, than the magnitude of Mo3e Ag expressed on the surface. PMA stimulation not only induced an increase in the relative proportion of Mo3e antigen expressed on the surface membrane, but also stimulated a 1.8-fold increase in "total" Mo3e detectable in permeabilized cells. Trypsin treatment of intact PMA-stimulated U-937 cells eliminated surface Mo3e expression but had little measureable effect on the total Mo3e pool. Permeabilization also uncovered a sequestered compartment of Mo3e Ag in I-937 cells, a variant of U-937 that is surface Mo3e negative. Although the PMA-induced surface Mo3e expression of U-937 was abrogated by cycloheximide, the total pool of Mo3e detectable in permeabilized PMA-stimulated cells was only partially reduced; cycloheximide treatment caused no reduction in the intracellular Mo3e compartment of unstimulated U-937 cells. Detergent lysates of PMA-stimulated U-937 cells exhibited undiminished quantities (relative to untrypsinized cells) of p75 and p50 proteins immunoreactive with anti-Mo3e mAb as detected by Western blotting. This trypsin-sequestered intracellular Mo3e Ag may serve as a reservoir for the up-regulated surface expression of Mo3e that occurs as a result of mononuclear phagocyte activation.

Antibodies, Monoclonal↗
PubMed1988

Expression of Mo3e antigen by cultured human umbilical vein endothelial cells (HUVEC) stimulated by phorbol myristate acetate (PMA) and related pharmacological inducers of protein kinase C.

Mo3e is a protease-sensitive membrane antigen (p75,50) selectively expressed by human monocytic cells (monocytes and U-937 cells) stimulated in vitro by exposure to a variety of activating factors, including phorbol diester compounds, bacterial lipopolysaccharide (LPS), and muramyl dipeptide (MDP)(R.F. Todd et al., J. Immunol. 135, 3869, 1985). Here we report that primary and multiply-passaged cultures of HUVEC also express the Mo3e determinant after stimulation by phorbol myristate acetate (PMA) and related inducers of protein kinase C. As measured in a radioimmunoassay of anti-Mo3e antibody binding to monolayer cultures of HUVEC, unstimulated cells bore little if any Mo3e. After culture for 4-120 hr in medium containing PMA, 4 beta-phorbol dibutyrate, 4 beta-phorbol didecanoate, or mezerein (each at a concentration of 81 nM), or 1-oleoyl-2-acetoyl-sn-3-glycerol (1 mM), HUVEC were found to selectively express the Mo3e determinant. The magnitude of expression was dependent upon the concentration of the stimulus, maximal by 24 hr, and inhibited by cycloheximide. The combination of PMA and the calcium ionophore, ionomycin, had an additive or synergistic effect on HUVEC Mo3e expression. The biologically inactive phorbol compounds 4 beta-phorbol and 4 alpha-phorbol didecanoate failed to stimulate Mo3e expression. Also inactive as inducers of HUVEC Mo3e expression were crude lymphokine and monokine supernatants, recombinant human lymphokines (interferon-gamma and interleukin-2), recombinant human monokines (interleukin-1 and tumor necrosis factor), bacterial cell wall products including LPS and MDP, pharmacologic agents that increase intracellular cyclic adenosine monophosphate (prostaglandin E2, cholera toxin, theophylline, isoproterenol and isobutylmethylxanthine), lectins (Con A and PHA), and heparin. These results indicate that Mo3e is an inducible plasma membrane antigen of not only mononuclear phagocytes but also cultured HUVEC.

Animals↗
PubMed1988

The use of in vitro fertilization to evaluate putative tests of human sperm function.

Results of 106 in vitro fertilization procedures were used to evaluate the usefulness of tests of human sperm function for predicting fertilization rates. Sperm tests included concentration, motility, morphology, vitality (eosin Y exclusion), nuclear immaturity (aniline blue stain), and hypo-osmotic swelling. Only the number of sperm in the insemination medium, percentage normal morphology, and vitality were statistically significant in logistic regression models of fertilization rates. The other tests, such as the hypo-osmotic swelling test, did not give additional information about fertilization rates in this study. It is concluded that logistic regression analysis of factors affecting results of fertilization in vitro provides a powerful tool for evaluating some clinical tests of sperm function.

Female↗
PubMed1988

The proportion of human sperm with poor morphology but normal intact acrosomes detected with Pisum sativum agglutinin correlates with fertilization in vitro.

Sperm acrosomes were examined with fluorescein-labeled pisum sativum agglutinin in 137 in vitro fertilization treatments. The percentage of sperm with normal intact acrosomes in semen was correlated with sperm concentration, morphology, viability, and motility. The proportion of sperm with normal intact acrosomes was significantly increased by the "swim up" selection from semen. Fertilization rates in the whole group studied were significantly related to percentage normal morphology, concentration of sperm inseminated and cause of infertility. However, with normal morphology less than 30%, the proportion of sperm with normal intact acrosomes in the insemination medium was the only significant factor related to fertilization rate in the logistic regression analysis. Thus, assessment of acrosomes may be of clinical value for predicting the fertility of men with poor sperm morphology.

Acrosome↗
PubMed1988

A human sperm-zona pellucida binding test using oocytes that failed to fertilize in vitro.

A test for human sperm binding to the zona pellucida (ZP) was developed using oocytes which failed to fertilize in vitro. Heterospermic insemination with equal numbers of test and fertile donor sperm differentially labeled with fluorescein isothiocyanate or tetra-methylrhodamine B isothiocyanate controlled for variability in ZP-sperm binding capacity. The number of sperm bound to the ZP was independent of previous sperm binding in in vitro fertilization (IVF), preservation of the ZP in salt solution, and fluorochrome labeling but increased linearly with time and sperm concentration. Sperm from men who had one or more failed attempts at IVF with no or few oocytes fertilized usually displayed very low ZP binding ratios of test to normal sperm. This test may predict the ability of sperm to fertilize human oocytes in vitro and should be useful in studies of human gamete interaction.

Female↗
PubMed1988

Mutagenicity of gossypol analyzed by induction of meiotic micronuclei in vitro.

Chromosome breakage caused by mutagens in male germ cells can be analyzed by micronucleus induction during meiotic division. This can be followed in vitro by culturing seminiferous tubular segments from stages of the epithelial cycle that contain late pachytene and diakinetic primary spermatocytes. We studied the mutagenic potential of a male contraceptive, gossypol, in this test system using adriamycin (10 ng/ml) as a reference mutagen. A small but significant increase in the frequency of micronuclei was induced with concentrations of 10 and 20 micrograms/ml of gossypol, while cytotoxic effects appeared at concentration of 20 micrograms/ml and were evident at 50 micrograms/ml. Analysis of meiotic micronucleus induction in vitro seems to be a sensitive test system of male germ-cell mutagenesis, but further studies on the possible mutagenic effects of gossypol are needed.

Animals↗
PubMed1987

Expression of an activation antigen, Mo3e, associated with the cellular response to migration inhibitory factor by HL-60 promyelocytes undergoing monocyte-macrophage differentiation.

HL-60 promyelocytic cells acquire the surface expression of the Mo3e antigenic determinant after exposure to PMA or compounds that raise intracellular concentrations of cyclic AMP (dibutyryl cyclic AMP or a combination of cholera toxin and IBMX). The expression of Mo3e by these stimulated HL-60 cells coincides with the development of features of monocyte-macrophage differentiation (characteristic morphology, nonspecific esterase activity, and respiratory burst activity). During in vitro monocyte-macrophage differentiation, HL-60 cells become responsive to migration inhibitory factor (MIF); the MIF responsiveness of differentiated HL-60 cells is blocked by anti-Mo3e monoclonal antibody. These findings further support the relationship between the expression of Mo3e and the cellular response to MIF.

Antibodies, Monoclonal↗
PubMed1987

Spermatozoal nuclear chromatin decondensation in vitro: a test for sperm immaturity. Comparison with results of human in vitro fertilisation.

Human sperm immaturity was tested by nuclear chromatin decondensation (NCD) in 1% sodium dodecylsulphate (SDS) of spermatozoa used in 74 consecutive IVF treatments. NCD was significantly higher in the presence of 2 mmol/l dithiothreitol (DTT) and after washing sperm from semen with 6 mmol/l ethylenediaminetetraacetic acid (EDTA). NCD was significantly less in insemination suspensions prepared by the swim-up technique than in the original semen. NCD with DTT was inversely correlated with sperm motility and motility index but there were no significant relationships between NCD and other semen analysis variables. There was no significant correlation between any NCD test and the proportion of oocytes fertilised in vitro. The only factors being significantly correlated with the fertilisation rate were proportion of sperm with normal morphology (Kendall correlation, tau = 0.36, P less than 0.001) and sperm concentration (tau = 0.14, P less than 0.05). Logistic regression analysis of fertilisation rates showed that only percentage normal sperm morphology was significant. It is concluded that NCD does not provide additional useful clinical information about sperm fertilising ability in vitro.

Cell Nucleus↗
PubMed1986

A monoclonal antibody specific for a monocyte-macrophage membrane component blocks the human monocyte response to migration inhibitory factor.

In our study of the human monocyte response to migration inhibitory factor (MIF), we screened murine anti-monocyte monoclonal antibodies (MAb) for their ability to affect the MIF response. When blood monocytes were preincubated for 30 min at 37 degrees C with MAb of various cell specificities, it was found that Mo3e-MAb could inhibit the monocyte response to MIF. This effect was observed at an antibody concentration of 0.37 microgram/10(6) monocytes. This blocking activity appeared to be specific for Mo3e-MAb, since MAb specific for Mo1, Mo2, Mo4, alveolar macrophage (PAM-1), and platelet (Plt-1) antigens were unable to block the MIF response. Specificity was also shown by experiments performed with MAb similar to Mo3e-MAb in their immunofluorescence staining patterns. Two MAb of this type were not able to block the MIF response. All of these MAb are of the IgM isotype, and therefore it is unlikely that the blocking activity of Mo3e-MAb is mediated by the Fc receptor. These studies suggest that Mo3e-MAb may represent an anti-MIF receptor antibody. Mo3e-MAb recognizes a protease-sensitive antigen of 80 kD and 50 kD that is weakly expressed on fresh blood monocytes but is up-modulated by stimulation of monocytes with bacterial lipopolysaccharide, muramyl dipeptide, or phorbol compounds. Mo3e is also expressed by human myeloid cell lines, U-937 and HL-60, that have been stimulated in culture by biologically active phorbol diester compounds.

Antibodies, Monoclonal↗
PubMed1986

The effect of serum on motility of human spermatozoa in culture.

The motility of spermatozoa was higher at 6-22 h in Ham's F10 culture medium supplemented with 20-30% human serum than with lower proportions of serum or with 1% human serum albumin. Heat treatment (56 degrees C, 1 h), charcoal extraction and dialysis (18,000 molecular weight cut-off) of the serum did not reduce sperm motility suggesting that high molecular weight components are responsible for maintenance of motility. Renewing the medium (Ham's F10 with 30% serum) at 7 h resulted in better sperm motility and velocity at 22 h. At 22 h the pO2, pCO2, pH and sodium concentrations were not different in replenished and control cultures, but the concentration of glucose was higher and that of potassium lower if the medium was changed. These results suggest that addition of 20-30% human serum and renewal of medium at intervals is beneficial for sperm culture and may be of use in in vitro fertilization.

Blood↗
PubMed1986

Mononuclear phagocyte activation: activation-associated antigens.

Mononuclear phagocyte activation is characterized by alterations in cellular metabolism and plasma membrane composition. In rodent and human systems, antibodies (conventional heteroantibodies or monoclonal reagents) that identify plasma membrane antigens selectively expressed by activated macrophages and monocytes have been generated. Among these activation-associated determinants is Mo3e (p50,80), a protease-sensitive antigen that is expressed by human monocytes activated in culture by exposure to bacterial lipopolysaccharide, muramyl dipeptide, or phorbol myristate acetate (PMA) (as well as other biologically active phorbol compounds). Mo3e is also expressed by the monoblastic cell line U-937 after culture in medium containing PMA and other pharmacological activators of protein kinase C (4 beta-phorbol-12,13-dibutyrate, 4 beta-phorbol-12,13-didecanoate, mezerein, and cell-permeable 1,2-diacylglycerol). The human promyelocytic cell line HL-60 becomes Mo3e positive after exposure in vitro to certain inducers of monocytic differentiation (PMA, dibutyryl cyclic AMP, and cholera toxin plus 3-isobutyl-1-methylxanthine). The surface expression of Mo3e is blocked by inhibitors of protein synthesis, N-linked glycosylation, and protein kinase activation, as well as by ethylene glycol bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid and calcium antagonists. These data suggest the involvement of glycoprotein synthesis, protein kinase activation, and calcium ions in the stimulated expression of Mo3e by activated human mononuclear phagocytes. Anti-Mo3e antibody blocks the human monocyte response to migration inhibitory factor (MIF), which indicates an association between the expression of Mo3e antigen and responsiveness to MIF.

Animals↗