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Biomedical subjects

S Yagel

Publications and source records attributed to S Yagel.

At least 127 records · Page 7Linked to original sources
PubMed1991

Increased middle cerebral artery blood flow impedance in fetal subdural hematoma.

This case describes the prenatal diagnosis at 30 weeks' gestation of a posterior fossa subdural hematoma. Doppler velocimetry studies of the middle cerebral artery at that time showed an abnormally high resistance pattern with reverse end-diastolic flow. Ultrasonic assessment of the fetus indicated that there was associated quadriplegia. No cause for the lesion was demonstrated. A fetal blood sample, obtained by cordocentesis, revealed a normal karyotype. Fetal blood gas analysis was also normal. The pregnancy was terminated at the parents' request.

Journal Article↗
PubMed1990

Characterization and localization of human placental mononuclear phagocytes by monoclonal antibodies and other cell markers.

Human first-trimester placental macrophages were identified in frozen tissue sections and following cultivation as single-cell suspensions. In placental sections, the placental macrophages were shown to be the main cell type of the stromal zone. They clearly expressed macrophage-specific antigen, identified by EBM 11 monoclonal antibody; all were positive for nonspecific esterase (NSE), and 40-60% of them expressed the HLA-DR antigen. These cells were negative to anti-alpha-human chorionic gonadotropin (HCG) monoclonal antibody. After preparation of the placental single-cell suspension, the macrophages comprised about 15% of the total cell population. This fact was established by the following findings: 15% of the placental cell suspension expressed the antigen recognized by the OKM5 antibody, 16% expressed the EBM 11 antigen, 13% expressed the HLA-DR antigen, 5.5% were positive for NSE, and 24% phagocytosed Staphylococcus albus. Thirty percent of the cells were positive to anti-alpha-HCG antibody. After 48 h of cultivation in defined tissue culture conditions, the macrophages comprised more than 95% of the culture cell population. In the 48-h cultures, 98% of the cells expressed the macrophage antigens identified by OKM5 and EBM 11 monoclonal antibodies, and 75% expressed the HLA-DR antigen; 95% were positive for NSE, 88% of the cells had Fc receptors, and 95% of them were able to phagocytose S. albus. Only 0.1% of the culture cell population were positive to anti-alpha-HCG monoclonal antibody. These assays showed that the placental macrophages are the main cells in the placental stroma. In our tissue culture conditions, incubation time was shown to be the dominant factor in selecting macrophages over other cell types, most probably because the macrophages are the only placental cells that have the ability to adhere to plastic dishes. This observation might also explain the contradictory results in various studies over the last decade, regarding the incidence of the placental mononuclear macrophages.

Antibodies, Monoclonal↗
PubMed1989

Evidence that beta 1-6 branched Asn-linked oligosaccharides on metastatic tumor cells facilitate invasion of basement membranes.

In previous studies we have shown that the ability of murine tumor cells to metastasize in situ is directly linked to expression of -GlcNAc beta 1-6Man alpha 1-6Man beta 1-branched complex-type Asn-linked oligosaccharides in tumor-cell glycoproteins. Here we demonstrate that cell-surface expression of beta 1-6 branched oligosaccharides in metastatic tumor cells is specifically associated with increased invasion of human amnion basement membranes in vitro. Compared to nonmetastatic SP1 murine mammary carcinoma cells, 2 metastatic sublines expressed higher levels of beta 1-6 branched oligosaccharides and were found to be invasive but poorly adhesive on the amnion basement membrane. Swainsonine, a non-toxic inhibitor of Asn-linked oligosaccharide processing which blocks the pathway prior to initiation of the beta 1-6 linked antenna, blocked metastatic tumor-cell invasion and increased adhesiveness. Swainsonine and the metalloprotease inhibitor O-phenanthroline inhibited invasion, apparently via independent mechanisms. O-phenanthroline did not affect tumor-cell adhesion to the amnion basement membrane and swainsonine did not block secretion of metalloproteases, beta-hexosaminadase or tissue plasminogen activator activity by the tumor cells. These results suggest that tumor-cell invasion of basement membranes requires both secretion of hydrolase activities and expression of beta 1-6 branched complex-type oligosaccharides at the tumor cell surface, such oligosaccharides being associated with reduced tumor-cell adhesion to extracellular matrix.

Alkaloids↗
PubMed1989

Suppression by cathepsin L inhibitors of the invasion of amnion membranes by murine cancer cells.

Cysteine proteinases, particularly cathepsins B and L, have been strongly implicated in fostering metastasis in mice. In this work four different inhibitors of cysteine proteinases have been shown to inhibit the invasion of the human amnion by murine melanoma and mammary carcinoma cells in vitro. Two of the inhibitors are synthetic peptides [ZPhePheCHN2 (benzyloxycarbonyl-L-phenylalanyl-L-phenylalanyldiazomethane) and ZPheAlaCH2F [3-(N-benzyloxycarbonylphenylalanylamido)-DL-1-fluoro-2-butanone]] and two are thiol protease inhibitors (TPIn, TPId) isolated from the skeletal muscle of the hind limbs of normal and dystrophic mice, respectively. The inhibitors (ZPhePheCHN2, TPId), with apparent selectivity for cathepsin L, blocked invasion as effectively as inhibitors (ZPheAlaCH2F, TPIn) effective on both cathepsins. The data reveal that in these cell lines the cysteine proteinases contribute significantly to the invasive capacity of the cells, but to a lesser extent than do the metalloproteinases. We suggest that the cysteine proteinases facilitate the action of metalloproteinases (collagenase, gelatinase, and stromelysin), possibly by activating them, by inactivating the tissue inhibitor of metalloproteinases, and/or by making basement membrane matrix more accessible.

Amnion↗
PubMed1989

Mechanisms of cellular invasiveness: a comparison of amnion invasion in vitro and metastatic behavior in vivo.

We employed a sensitive in vitro amnion invasion assay to examine the relationship of the invasive ability of numerous mouse and human tumor cell lines and their variants to their ability to spontaneously or artificially metastasize; we also studied possible enzymatic activities involved in the in vitro invasion process. In vitro invasive ability of tumor cells was strongly correlated with spontaneous metastatic ability from the subcutaneous site, regardless of the ability of tumor cells to form artificial metastases when introduced intravenously. However, normal nontumorigenic human trophoblast cells were also highly invasive. Various collagenase inhibitors totally abrogated amnion penetration by all invasive cells; various inhibitors of plasmin, plasminogen, and plasminogen activators prevented invasion in most, but not all, cases. Thus, amnion penetration provides a rigorous test for tumor cell invasiveness required for spontaneous metastasis in vivo, and invasiveness is strongly dependent on metalloproteinase activity, which usually follows plasmin activation.

Amnion↗
PubMed1989

PGE2-mediated immunosuppression by first trimester human decidual cells blocks activation of maternal leukocytes in the decidua with potential anti-trophoblast activity.

We have earlier shown that first trimester human decidual cells and decidual macrophages suppress T lymphocyte alloreactivity in an MHC-unrestricted manner by secreting PGE2, which blocks the generation of IL-2 receptors (IL-2R) and production of IL-2 by lymphocytes but does not interfere with the interaction between IL-2 and IL-2R or the lytic function of CTL, once generated. The present study examined whether these events constituted a physiological, immunoprotective mechanism in situ against the activation of maternal decidua-infiltrating leukocytes with potential anti-trophoblast cytocidal function. We examined (1) whether there was IL-2R expression, IL-2 production, or anti-trophoblast killer activity in short-term (0-3 day) cultures of collagenase-dispersed first trimester human decidua inclusive of leukocytes; (2) if not, whether any of these parameters could be stimulated in these cultures by blocking PGE2 synthesis with indomethacin, or neutralizing PGE2 with anti-PGE2 antibody; (3) whether exogenously added recombinant IL-2 in the presence or absence of indomethacin stimulated IL-2R expression or anti-trophoblast killer function in these cultures. IL-2R (as defined by Tac antigen) was measured in the whole cell population by a radioimmunoassay and further examined at the cellular level with radioautography. IL-2 production in culture supernatants was measured from the proliferative response (3HTdR uptake) of an IL-2-dependent (CTLL) cell line. Killer activity in fresh or cultured decidua-associated cells as well as PBL of normal or pregnant subjects was measured against 51Cr-labeled targets inclusive of autologous cytotrophoblast cells or long-term human trophoblast cell lines, K562 and Daudi cells. Results revealed a complete absence of IL-2R expression, IL-2 production, or anti-trophoblast killer activity in the untreated cultures of the decidua, but all these parameters were significantly stimulated in the presence of indomethacin or anti-PGE2 antibody. The indomethacin-stimulated killer cells had NK-like activity. Presence of high dose exogenous IL-2 alone in these cultures strongly stimulated IL-2R expression and anti-trophoblast killer function, which were augmented further in the additional presence of indomethacin. The resultant killer cells had LAK cell-like activity. These findings suggest that PGE2 secretion by first trimester human decidual cells blocks activation of maternal leukocytes in the decidua with potential anti-trophoblast killer function, by inhibiting IL-2 receptor generation and IL-2 production in situ.

Cytotoxicity, Immunologic↗
PubMed1989

Antisense RNA-induced reduction in murine TIMP levels confers oncogenicity on Swiss 3T3 cells.

Mouse 3T3 cell lines capable of constitutively synthesizing an RNA complementary to the messenger RNA encoding TIMP, tissue inhibitor of metalloproteinases, were constructed by transfection with appropriate plasmid constructs. Many of the lines were down-modulated for TIMP messenger RNA levels and secreted less TIMP into the culture medium. In comparison to noninvasive, nontumorigenic controls, these cells not only were invasive in a human amnion invasion assay, but also were tumorigenic and metastatic in athymic mice. These results indicate that TIMP suppresses oncogenicity, at least in immortal murine 3T3 cells.

Animals↗
PubMed1989

Characterization of pure human first-trimester cytotrophoblast cells in long-term culture: growth pattern, markers, and hormone production.

Pure long-term cytotrophoblast cultures were established from human first-trimester placentas by growing chorionic villus explants without enzymatic digestion. Cytoplasmic human chorionic gonadotropin was detectable in all (100%) cells in culture when labeled with a polyclonal anti-human chorionic gonadotropin antibody and in 71% to 83% of cells labeled with a monoclonal anti-alpha-human chorionic gonadotropin antibody. Most of the cells expressed cytokeratin and surface Trop-1 and Trop-2 antigens (89% to 95%), but none expressed cytoplasmic vimentin or surface 63D3 antigens. Study of the ultrastructure of the cells demonstrated epithelial morphologic features. The average doubling time of the trophoblast was 48 to 96 hours. Some of the lines have been continuously propagated for 8 months. They produced variable amounts of human chorionic gonadotropin (50 to 710 mIU/ml per 10(5) cells per 24 hours). The basal level of progesterone secreted by trophoblast (444.4 +/- 32.4 pg/ml per 10(5) cells per 24 hours) doubled in the presence of pure human chorionic gonadotropin (100 ng/ml). They produced small amounts of 17 beta-estradiol (less than 20 pg/ml per 10(5) cells per 24 hours); human chorionic gonadotropin had no effect on the estradiol production. Trophoblast-derived human chorionic gonadotropin acted as a growth factor because trophoblast proliferation (measured by uptake of thymidine labeled with tritium) was reduced by 60% in the presence of an anti-human chorionic gonadotropin antibody. Availability of pure, functionally competent human cytotrophoblast in long-term cultures is relevant for further studies in reproduction biology.

Antigens↗
PubMed1989

Trophic effects of first-trimester human trophoblasts and human chorionic gonadotropin on lymphocyte proliferation.

We examined the effects of pure first-trimester human trophoblast cells grown in long-term cultures or their secreted products on the proliferation of human peripheral blood lymphocytes cultured alone, under allogeneic stimulation, or in the presence of concanavalin A. Both trophoblasts and their culture supernatants stimulated lymphocyte proliferation. Culture supernatant had a moderate enhancing effect on lymphocyte mitogenesis in mixed lymphocyte cultures and in the presence of concanavalin A. Anti-human chorionic gonadotropin antibody suppressed the proliferative effect of trophoblast cells and their supernatants in the above experiments in a dose-dependent manner. At physiologic concentrations, both pure and impure forms of human chorionic gonadotropin enhanced (in a dose-dependent manner) proliferation of lymphocytes cultured alone (peak stimulation index, 6 to 7.8 at approximately 7 IU/ml). At higher concentrations (20 to 400 IU/ml) the proliferative effect was abolished. Trophoblast culture supernatant induced the expression of interleukin-2 receptors on lymphocytes after 48 hours of incubation. The supernatant also stimulated proliferation of human colon carcinoma cells. Thus trophoblast or trophoblast-derived human chorionic gonadotropin has a lymphocytotrophic function that may have implications for fetal survival.

Carcinoma↗
PubMed1989

Interleukin-1 stimulates human chorionic gonadotropin secretion by first trimester human trophoblast.

Interleukin-1 (IL-1) has been reported to stimulate LH, GH, ACTH, and TSH release from cultured pituitary cells. IL-1 also has been found to be secreted in significant amounts by placental macrophages. To determine the possible role of IL-1 within the placenta, we studied the effects of human recombinant IL-1 on hCG release by long term cultures of human first trimester trophoblast and the JAR (human choriocarcinoma) cell line. IL-1 in concentrations ranging from 10(-11)-10(-9) mol/L stimulated hCG release from trophoblast cultures. This stimulatory effect was not mediated by prostaglandin E2 (PGE2), as indicated by the inability of indomethacin to block this stimulation as well as a lack of IL-1 effect on PGE2 release by trophoblast cells. At these doses, IL-1 exerted no effect on hCG release by JAR cells. PGE2, when used in high concentrations (10(-6)-10(-5) mol/L), stimulated the release of hCG by the trophoblasts as well as by the JAR cells. Neither IL-1 nor PGE2 stimulated the proliferation, [3H]thymidine incorporation, or differentiation (syncytium formation) of trophoblast or JAR cells. These results suggest that IL-1 may be an important local regulator of hCG secretion by first trimester trophoblasts.

Cell Division↗
PubMed1989

Studies of normal and prematurely ruptured human amniotic membranes: low calcium and magnesium in prematurely ruptured membranes.

Prematurely ruptured amniotic membranes at term, and membranes from normal term pregnancies were studied. The membranes were analyzed for neutral sugars, hexosamines, sialic acid, uronic acid, DNA, RNA, cholesterol, phospholipids, calcium, magnesium, sodium and potassium. The only significant difference found between the normal and the prematurely ruptured membranes was a significantly lower concentration of calcium and magnesium in the latter group. (Calcium 0.32 +/- 0.07, vs. 0.24 +/- 0.07, p less than 0.05; Magnesium 0.30 +/- 0.19 vs. 0.15 +/- 0.04, p less than 0.05; in mg/100 mg protein). The possible metabolic effects of low calcium and magnesium may be of relevance to the pathogenesis of premature rupture of the amniotic membranes.

Calcium↗
PubMed1989

Asparagine-linked oligosaccharides associated with metastatic cancer.

Malignant transformation and tumor progression are often accompanied by structural changes in the carbohydrate components of glycoproteins and glycolipids. Studies with tumor cell glycosylation mutants and specific inhibitors of glycosylation indicate that expression of sialylated and beta (1-6) branched asparagine (Asn)-linked oligosaccharides are required for tumor cell invasion and metastasis. The initiation of the beta (1-6) antenna appears to be oncodevelopmentally regulated and may be associated with the aberrant expression of blood group and embryonic carbohydrate sequences in Asn-linked oligosaccharides of tumors. Although the function of these oligosaccharides in the metastatic process remains unclear, there is some evidence that expression of these structures on certain cell-surface glycoproteins may reduce tumor cell adhesion to extracellular matrix. These observations suggest that low-toxicity drugs that inhibit the biosynthesis of these structures may be useful in the treatment of metastatic cancers.

Animals↗