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Biomedical subjects

D Y Liu

Publications and source records attributed to D Y Liu.

At least 127 records · Page 7Linked to original sources
PubMed1986

Seminal transferrin, an index of Sertoli cell function: is it of clinical value?

To determine the clinical value of seminal transferrin measurements, transferrin concentrations in seminal plasma were determined by single radial immunodiffusion. Men with various disorders of spermatogenesis had significantly lower mean values than those with normal semen (170 micrograms/ejaculate, s.e.m. = 18.4), oligospermia (40.5 micrograms, s.e.m. = 7.2) or azoospermia due to primary seminiferous tubule failure (65.9 micrograms, s.e.m. = 29.1). In these subjects with patent genital tracts, seminal transferrin was directly correlated with sperm concentration and indirectly correlated with serum FSH levels. Seminal transferrin increased following gonadotrophin treatment of men with gonadotrophin deficiency from 19.6 micrograms (s.e.m. = 5.5) to 108.6 micrograms (s.e.m. = 31.7). Patients with genital tract obstructions also had low levels; vasal agenesis (21.8 micrograms, s.e.m. = 5.6), vasectomy (48.5 micrograms, s.e.m. = 21.0), epididymal obstruction (46.6 micrograms, s.e.m. = 7.1). These results confirm that most seminal transferrin comes from the testes and reflects Sertoli cell function. However, there is a very wide range of transferrin levels in normal semen and a number of normospermic samples have low values similar to those seen with abnormal Sertoli cell function or obstruction. Thus, measurement of seminal transferrin is of limited diagnostic value.

Genital Diseases, Male↗
PubMed1986

Regulation of human monocyte surface antigen expression. I. Up-modulation of Mo3e antigen expression on U-937 and HL-60 cells stimulated by pharmacologic activators of protein kinase C.

Mo3e is a protein (p 50,80) that is expressed on the surface of human monocytic cells after exposure in vitro to soluble activating factors that include bacterial lipopolysaccharide, muramyl dipeptide, and phorbol myristate acetate (PMA). The surface expression of Mo3e may represent a cellular event that occurs in response to the formation of "secondary messengers" that include diacylglycerol, inositol trisphosphate, and calcium ions. This postulate is based on the stimulatory effect of agents that can mimic the activity of endogenous diacylglycerol (PMA and other biologically active phorbol compounds, mezerein, and L-alpha-1,2 dioctanoylglycerol) and inositol trisphosphate (ionomycin) on Mo3e expression by U-937 and HL-60 cells. The inhibitory effect of phospholipid-active calmodulin inhibitors (trifluoperazine, chlorpromazine, and dibucaine), calcium antagonists (nicardipine and TMB-8), and EGTA further support the involvement of phospholipid- and calcium-dependent protein kinase (protein kinase C) and calcium ions in the up-modulation of Mo3e surface expression.

Antigens, Surface↗
PubMed1985

Glycolipid receptor for human migration inhibitory factor: fucose and sialic acid are important for the human monocyte response to migration inhibitory factor.

The role of carbohydrate in the interaction of human migration inhibitory factor (MIF) with human peripheral blood monocytes was investigated by studying the effects of different exoglycosidases on the cellular response to MIF. When monocytes were pretreated with neuraminidase, an exoglycosidase specific for sialic acid, they became unresponsive to MIF. Other glycosidases, such as beta-galactosidase and alpha-mannosidase, were inactive in this respect. The effect of neuraminidase was reversible since the response to MIF was restored to normal levels after 24 hr. In parallel studies, a glycolipid-enriched extract from U937 cells, a human macrophage-like cell line, known to enhance the monocyte response to MIF, lost this activity when treated with neuraminidase and alpha-L-fucosidase, but not with beta-galactosidase. This suggests the importance of terminal sialic acid and fucose residues for the interaction between monocyte membrane glycolipids and MIF.

Cell Line↗
PubMed1985

Macrophage glycolipid receptors for human migration inhibitory factor (MIF): differentiated HL-60 cells exhibit MIF responsiveness and express surface glycolipids which both bind MIF and convert nonresponsive cells to responsiveness.

The human promyelocytic leukemia line HL-60 when treated with a phorbol diester (TPA) differentiates into cells (HL60-TPA) that respond to human migration inhibitory factor (MIF). Unresponsive HL-60 cells became responsive to MIF when preincubated with a glycolipid-enriched preparation extracted from HL60-TPA cells, human monocytes, human macrophage-like (U937) cell line, or with the purified glycolipid receptor for MIF from guinea pig peritoneal macrophages. Human blood monocytes exhibited an increased response to MIF when preincubated with glycolipids from HL60-TPA and U937 cells but not from HL-60 cells. Finally, glycolipids from HL60-TPA cells but not from HL-60 cells were able to reversibly bind MIF when covalently coupled to agarose. These studies suggest that TPA induces the differentiation of HL-60 cells into MIF-responsive cells through the expression of a glycolipid receptor for MIF.

Cell Differentiation↗
PubMed1985

Bacterial lipopolysaccharide, phorbol myristate acetate, and muramyl dipeptide stimulate the expression of a human monocyte surface antigen, Mo3e.

Exposure of mononuclear phagocytes to bacterial lipopolysaccharide (LPS), phorbol myristate acetate (PMA), or muramyl dipeptide (MDP) is known to stimulate a variety of cellular activities that include increases in phagocytosis, oxidative metabolism, synthesis and secretion of monokines, and cytotoxicity of microbes and tumor cells. We now report that culture of human peripheral blood monocytes in medium containing LPS, phorbol compounds, or MDP also results in the acquired expression of a plasma membrane antigen. Mo3e, as identified by a murine monoclonal antibody. Mo3e is barely detectable (by immunofluorescence flow cytometry) on freshly isolated monocytes, but is expressed in high antigen density after exposure of cells to E. coli, Salmonella minnesota, or Serratia marcescens LPS (at concentrations exceeding 0.1 ng/ml), PMA (and other biologically active phorbol compounds) (0.5 to 1 X 10(-8) M), or MDP (0.01 to 1 X 10(-6) M). Mo3e expression stimulated by LPS is prevented by pretreatment of LPS with polymyxin B, suggesting that the lipid A portion of LPS is responsible for Mo3e induction (polymyxin B has no effect on Mo3e expression stimulated by PMA or MDP). Culture of monocytes in medium containing protein synthesis inhibitors (or at 4 degrees C) blocks the acquisition of Mo3e. Recombinant IFN-gamma, which is also known to "activate" mononuclear phagocytes, does not stimulate Mo3e expression, although both LPS and IFN induce enhanced expression of monocyte Ia antigen. Analogous to their stimulatory effect on monocytes, LPS and PMA induce Mo3e expression by the human monocytic cell line, U-937. On the basis of these observations, Mo3e may represent an immunologic marker for monocyte activation stimulated in vitro by LPS, PMA (and related compounds), and MDP.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1984

Glycolipid-dependent interaction between human migration-inhibitory factor and mononuclear phagocytes.

It has been previously established in the guinea pig that the response of peritoneal macrophages to migration inhibitory factor (MIF) is enhanced by a macrophage glycolipid and that gangliosides reversibly bind MIF. This suggests that glycolipids function as cell surface receptors for MIF. In this report, it is demonstrated that the response of human peripheral blood monocytes to human MIF is augmented by preincubation of these cells with glycolipid-enriched material extracted from the human macrophage-like cell line U937 or human peripheral blood monocytes and with a purified glycolipid from guinea pig peritoneal macrophages. In addition, a mixed ganglioside preparation from bovine brain shows the same effect. In contrast, the pure gangliosides, GM1 and GD1a, and glycolipids from the HL-60 cell line, which is a MIF-unresponsive cell line, were not able to enhance the response to human MIF. The specificity of enhancement by particular glycolipids could not be attributed to an increased uptake of only enhancing glycolipids since there was no significant difference between the association of monocytes with radioactive liposomes containing biologically active or inactive glycolipids. Pronase treatment did not affect the enhancing activity of the U937 glycolipid-enriched material. Incubation of cells with glycolipids results in enhancement only if done at 37 degrees C and not at 4 degrees C. Therefore, the association of lipid with the monocyte surface appears to be dependent on temperature. Further evidence for the receptor nature of these enhancing glycolipids is provided by experiments involving affinity purification experiments. Coupling of bovine brain mixed gangliosides to agarose resulted in a matrix capable of reversibly binding MIF. GD1a-agarose was inactive in this respect.

Animals↗
PubMed1984

Fetal weight estimation from lengths and volumes found by three-dimensional ultrasonic measurements.

A custom-built computer system combined with a commercial real-time ultrasonic scanner was used to predict fetal weight. A special three-dimensional (3D) locating system provided 3D coordinates of fetal surface points imaged on multiple ultrasound scans. The 3D coordinates were used to develop length and volume variables that are not available with commercial instruments. Multiple regressions were used to compare these lengths and volumes with more conventional diameters and circumferences for their ability to predict fetal weight. Measurements were made on 41 live fetuses within 48 hours prior to delivery (weight range 1,985-4,734 g, mean weight 3,421 g). Combinations of 19 measured variables were analyzed against birth weight and the natural log of birth weight. The correlation between log birth weight and combinations including lengths from 3D measurements was R = .93, SE = 73 g/kg. When volumes from 3D measurements (which are much more difficult to obtain) were added, the correlation was R = .94, SE = 69 g/kg. These results suggest that lengths from 3D measurements have the potential to improve fetal weight prediction by 25-30 per cent over current methods, which have an approximate error of 100 g/kg. The relative lack of improvement with volumes from 3D measurements is probably the result of technical problems which may be overcome with further research.

Birth Weight↗
PubMed1982

Fetal weight estimation from ultrasonic three-dimensional head and trunk reconstructions: evaluation in vitro.

The theoretical usefulness of volume as a predictor of fetal weight was assessed on 25 dead neonates with weight ranges between 364 and 3,650 gm. The correlation between volume, measured by water displacement, and weight was r = 0.999, with a standard error of 37 gm. A method is described for using volume, calculated from three-dimensional ultrasonic head and trunk reconstructions, to predict fetal weight. For the dead neonates, the correlation between measured weight and calculated head plus trunk volume was r = 0.985, with a standard error of 190 gm. The regression coefficient was 1.73, thus indicating that head and trunk volumes underestimate weight, as might be expected since limbs were not included. We conclude from this "ideal" situation that volume measurements will eventually provide the best estimates of fetal weight, and that three-dimensional head trunk reconstructions are reasonably accurate measures of overall volume.

Body Weight↗
PubMed1982

Isolation of a guinea pig macrophage glycolipid with the properties of the putative migration inhibitory factor receptor.

We have previously established that preincubation of guinea pig macrophages with crude preparations of macrophage glycolipids enhances their response to a mediator of cellular immunity, migration inhibitory factor. This biologically active moiety found in the extracted material was attributed to a single glycolipid component. This component was purified to homogeneity by phase partition, ion exchange, adsorption, and thin layer chromatography. It migrates in the ganglioside region on thin layer plates, contains sialic acid and sphingosine. There is no apparent identity with any of the common gangliosides possessing the gangliotetraose structure. Homogeneity was demonstrated by rechromatography in four additional solvent systems. These results are discussed in the context of their implications for a deeper understanding of the putative receptor function of this glycolipid.

Animals↗