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Biomedical subjects

E R Barnea

Publications and source records attributed to E R Barnea.

At least 19 recordsLinked to original sources
PubMed2001

Embryo maternal dialogue: From pregnancy recognition to proliferation control.

Embryo-maternal dialogue starts shortly after fertilization and is exerted through both local and systemic signaling. We have discovered specific embryo derived pre-implantation factors (PIF), novel peptides that are secreted already at the two cell stage and which modulate cellular immunity. In the fallopian tube the embryo, a partial allograft, is tolerated by the mother. Embryo derived peripheral signaling (PIF) is also detected prior to implantation in maternal sera. This signal may also help prime the endometrium to facilitate implantation. Upon implantation, embryo-endometrial communication becomes direct and highly amplified. When the immune privilege appears to be secured, embryogenesis proper initiates. This requires proliferation/differentiation to be tightly controlled. Knowledge of proliferation promoters is ample while the factors involved in its control remain less understood. We have identified a class of novel proteins/peptides, developmental proteins (DPs), that are present in the embryo before a mature immune system has developed. Their role is to create a balance between pro and antiproliferative forces, to promote normal proliferation while controlling abnormal cell proliferation (i.e. due to carcinogens, toxins, viruses, and ionic radiation). DPs, may also redirect growth towards functionality through differentiation. DPs appear to act through a specific receptor negating growth factors action through promotion of tumor suppressors and inhibition of tumor promoters at 2 minutes, blocking DNA synthesis at ~24 hours, and promoting apoptosis at ~48 hours. When an embryo becomes incompatible with life, DPs may lead to growth arrest, PIF-like compounds decline, the immune system to be restored and the pregnancy is rejected. Final identification and use of PIF and DPs is likely to help both managing early pregnancy disorders and aid in treatment of proliferative disorders due to cancer and viral infection.

Abortion, Spontaneous↗
PubMed1999

Progress in characterization of pre-implantation factor in embryo cultures and in vivo.

PROBLEM: Pre-implantation factor (PIF), a small, embryo-derived peptide is detected in the maternal serum prior to implantation and is associated with successful pregnancy outcome. However, its identity is not known. METHOD OF STUDY: PIF was isolated from mouse embryo conditioned media and from pregnant porcine sera, using high-performance liquid chromatography (HPLC) followed by mass spectrometry. RESULTS: Conditioned culture media was separated by gel filtration chromatography followed by reversed phase chromatography. At each step, PIF activity was determined by the lymphocyte/platelet binding autorosette assay (LPBA). Mass spectrometry yielded a single peak with a mass of 1300 Da. The peptide is, however, present in very low concentrations (fM), which has so far precluded complete identification. Pregnant porcine sera that exhibit potent PIF activity were deproteinated by acetone and further fractionated by reversed phase HPLC. Active fractions contain peptides of molecular masses 523 and 551 Da. CONCLUSION: PIF, likely to be peptides, represents a novel substance related to pregnancy initiation and maintenance.

Animals↗
PubMed1996

Response of human ovarian carcinoma cell lines to antiprogestin mifepristone.

The effects of antiprogestin mifepristone (MF) on the growth, progesterone receptor expression and cell cycle kinetics of several human ovarian epithelial carcinoma (OEC) cell lines were evaluated. MF, a synthetic antiprogestin, has been shown to have some antiproliferative activity in breast tumors and in the endometrium, but its efficacy in ovarian carcinomas has not been explored previously. Continuous exposure of OEC cells to MF resulted in a dose- and time-dependent growth inhibition, as determined by MTT assay. Growth inhibition was apparent by day three following addition of MF to cultures in vitro. All cell lines used in this study expressed a progesterone receptor (PR). MF down regulated PR expression on these cells. Changes in the cell cycle kinetics of OEC cells exposed to MF correlated with the observed antiproliferative effects. MF blocked cells in a G0/G1 phase of the cell cycle and thus reduced the number of cells in the S phase. The efficacy of MF was compared with that of taxol and tamoxifen in the same human OEC cell lines. Continuous exposure of OEC cells to tamoxifen resulted in a varied cytostatic response and a transient change in the cell cycle. Taxol inhibited growth of some but not all of the cell lines. These results indicate that PR-positive human OEC cells are sensitive to MF in vitro and that MF may be an active agent against ovarian epithelial tumors.

Antineoplastic Agents, Hormonal↗
PubMed1996

Embryonic origin of preimplantation factor (PIF): biological activity and partial characterization.

Preimplantation factor (PIF) is detected in the serum of women shortly after fertilization; its origin, however, has not been established. In this study, the embryonal origin of PIF was investigated and partial characterization of the factor was carried out. Culture media from viable human 2-8-cell stage embryos and mouse 2-cell-blastocyst stage embryos were analysed using the lymphocyte/platelet binding assay (LPBA). The assay was performed by combining culture media with donor O+ type blood-derived lymphocytes/platelets, complement and an antibody against CD2. Increased autorosette formation between lymphocytes and platelets (> 9%) was an indication for the presence of PIF. In addition, the effect of platelet-activating factor (PAF) and chaperonin 10 on PIF activity was determined. Partial purification of PIF was carried out using gel filtration and reverse-phase high purification liquid chromatography (HPLC), followed by mass spectrometry. Culture media of single human viable fertilized oocytes were negative for PIF; however, the 10-fold concentrated medium was positive for PIF. In medium in which five or more mouse embryos were cultured, PIF activity was observed starting at the morula stage and was higher by the blastocyst stage. Addition of PAF or chaperonin 10 to the PIF assay did not elicit a specific effect on PIF activity. Chromatographic data suggest that PIF activity is due to low molecular weight proteins. PIF appears to be a low molecular weight protein which is derived from viable preimplantation embryos. It is different from PAF or chaperonin 10. Its final characterization will be valuable for better understanding of maternal recognition of pregnancy and implantation.

Animals↗
PubMed1996

Development and validation of an assay for measuring preimplantation factor (PIF) of embryonal origin.

PROBLEM: Tests to determine presence of embryos prior to implantation are needed. METHODS: Sera from women after embryo transfer were tested for preimplantation factor (PIF) using the lymphocyte/platelet binding assay. Autorosettes were counted using blood type O+ donor lymphocytes and platelets incubated with blinded serum in the presence of antiCD2 antibody and rabbit complement. Human chorion gonadotropin (hCG) concentrations were determined 7 days later and compared with results of the lymphocyte/platelet assay. Implantation was confirmed by ultrasonographic evidence of presence of an intrauterine gestational sac. The roles of platelet activating factor (PAF) and chaperonin 10 in the observed phenomena were studied experimentally. RESULTS: Significantly more lymphocyte/platelet rosette formations were observed when sera from women who successfully implanted were compared to sera from women who failed to implant. Neither PAF nor chaparonin added to the tested sera controls influenced the percentage of lymphocyte/platelets rosettes. CONCLUSIONS: PIF is a likely candidate to be the next frontier of diagnosing the presence of viable preimplantation embryos in vivo.

Biological Factors↗
PubMed1996

Control of cell proliferation by embryonal-origin factors.

Embryogenesis can be paralleled and contrasted with cancerous cell proliferation; both embryogenesis and cancer are associated with extremely rapid cell proliferation. However, unlike cancer, embryogenesis is characterized by a delicate balance of proliferative and anti-proliferative processes. We have found two chromatographically separated fractions derived from human embryonal neural tissue extracts that significantly suppress the proliferation of human breast cancer cells. The reduction in cell number was time dependent, with maximal inhibition (70%) observed after 4 days of incubation while maintaining cell viability. The anti-proliferative effect was also evidenced by decreased [3H]-thymidine incorporation. Significant inhibition of proliferation of osteosarcoma, fibrosarcoma, and Balb/c 3T3 cell lines was also obtained with a low concentration of the active fractions. Embryonal factors inhibited mouse and rat cell lines, indicating cross-species effectiveness. The SDS-PAGE of the biologically active approximately 10.7 kDa region revealed several protein bands, while the biologically active approximately 4.5 kDa fraction contained only weakly stainable bands. Thus, the embryo contains factors that control the proliferation of malignant cells. These potent and possibly novel compounds should be investigated for their potential therapeutic role in cancer and other proliferative disorders.

3T3 Cells↗
PubMed1995

First-trimester villous placenta has high prorenin and active renin concentrations.

OBJECTIVE: Term villous placental concentrations of prorenin are known to be very low, whereas those of decidua and fetal membranes are high. It has been demonstrated that prorenin synthesis is modulated by hormones in other reproductive tissues, thus suggesting a means for paracrine regulation in the placenta. This study was performed to test the hypothesis that placental tissue prorenin concentrations may be influenced by gestational age and are temporally related to alterations in the hormonal milieu. STUDY DESIGN: Decidua and villous placental tissue were obtained from term and first-trimester human pregnancies, and concentrations of prorenin, active renin, prolactin, and human chorionic gonadotropin were measured. Values were compared between gestational periods, and relationships between renin and hormone values were analyzed. RESULTS: Prorenin concentrations in first-trimester placenta were nearly 200-fold higher than at term. The proportion of active renin was higher with early gestation. Decidual prorenin and active renin concentrations were similar in both groups. Placental prorenin correlated with chorionic gonadotropin but not prolactin in both groups. CONCLUSIONS: This study demonstrates large differences in placenta prorenin and active renin in villous placental tissue between first-trimester and term gestation tissues, yet these differences were not observed in decidual tissues. The contrast in placental prorenin values observed at the extremes of pregnancy parallel those of placental human chorionic gonadotropin.

Chorionic Gonadotropin↗
PubMed1995

Expression of quinone reductase activity in embryonal and adult porcine tissues.

Quinone reductase (QR; EC 1.6.99.2) is recognized as a major antimutagenic/anticarcinogenic enzyme in the organism. Our recent studies demonstrated the presence of significant QR activity in the early human placenta; whether this enzyme is expressed by the mammalian embryo is not known at present. In the investigation reported here, we sought to determine whether or not QR activity is detected in porcine embryonal tissues and if so, how early this expression takes place. In addition, the enzyme activity in the embryo was compared to that present in adult porcine tissue. Enzyme activity was determined by a colorimetric method with menadione as substrate in the presence of tetrazolium salt (MTT). NADH was a preferable cofactor in the embryo, whereas in the adult tissues NADPH was a better cofactor. Results show that the enzyme is present in all the embryonal organs tested from a very early age (30 days of gestation). Among the organs tested, activity was highest in the porcine embryo liver, and the specific activity remained unchanged until Day 70. Activity in the embryonal kidney increased with advancing gestation. The enzyme activity in embryonal tissues was much lower than that measured in the adult liver (30-40-fold). These findings suggest that the embryo has the potential for inactivating carcinogens/mutagens that will subsequently be eliminated by the maternal organism, thus protecting against adverse environmental impacts during the most critical period of development.

Animals↗
PubMed1995

Preimplantation factor (PIF) predicts subsequent pregnancy loss.

PROBLEM: To evaluate the ability of preimplantation factor (PIF) measured in the lymphocyte/platelet binding assay (LPBA) to predict subsequent spontaneous abortion. METHOD: Serum from 57 women experiencing first trimester pregnancy losses were studied using the LPBA (46 women conceived after in vitro fertilization and embryo transfer for treatment of infertility and 11 with a history of unexplained recurrent spontaneous abortion conceived spontaneously). The assay employs a combination of heat inactivated sera with donor O+ lymphocytes and platelets, complement and an antibody against CD2. Chromosome analysis was performed on 32 of the abortuses. Results of PIF assay were compared between karyotypically normal and abnormal abortuses. RESULTS: PIF assay was negative in all 57 women at the time of abortion. Among 12 karyotypically normal abortuses only 1 woman (8%) had an initial positive PIF, 11 (92%) had negative PIF. Serial PIF assays were performed on 15 women. PIF assay became negative a minimum of two weeks prior to demonstration of intrauterine demise at a time when hCG concentrations remained elevated. A trend to subnormal was seen in women with normal when compared to those with abnormal abortus karyotype, but the numbers were too small to reach statistical significance (P = 0.09). CONCLUSION: Measurement of PIF throughout the first trimester of pregnancy predicts subsequent pregnancy loss.

Abortion, Habitual↗
PubMed1995

A novel bioassay for detection of preimplantation factor (PIF).

PROBLEM: To identify the presence of vital preimplantation embryos in vivo in humans, a newly observed phenomenon based on autorosette formation between lymphocytes and platelets, when treated with pregnant sera, was used as a marker. METHOD: Serum samples were obtained from 65 patients on the fourth day after embryo transfer (ET). Sera from 10 healthy males and 47 nonpregnant women were used as controls. The preimplantation factor (PIF) was detected by using blood group O+ donor lymphocytes and platelets incubated with blinded serum in the presence of anti-CD2 antibody and rabbit complement. Human chorion gonadotropin (hCG) concentrations were determined 7 days later and compared with results of the lymphocyte-platelets assay. Implantation was confirmed by ultrasonographic evidence of presence of an intrauterine gestational sac. The role of platelet activating factor (PAF) in the observed phenomena was studied experimentally. RESULTS: Significantly more lymphocyte-platelet rosette formations were observed when sera from women who successfully implanted were compared to sera from women who failed to implant. This assay yielded a specificity of 95%, sensitivity of 88%, positive predictive value of 94%, and negative predictability of 90%. PAF added directly to the cell suspension and tested sera controls did not influence the percentage of lymphocyte/platelets rosettes. CONCLUSION: The application of PIF assay will enable the identification and study of early pregnancy events before the implantation occur. PAF by itself is not responsible for the rosette formation.

Biological Assay↗
PubMed1995

Peroxidase activity and glutathione content in the human first-trimester placenta and decidua.

OBJECTIVE: Recently, a novel pathway of xenobiotic oxidation by peroxidase in the placenta at term was described. Herein, we aim to determine the potential of the first-trimester placenta and decidua to activate carcinogens and mutagens by peroxidase and to scavenge free radicals by glutathione. METHODS: Placental and decidual peroxidase activity was measured using a sensitive, quantitative colorimetric kinetic assay, with O-phenylenediamine dihydrochloride (OPD) as substrate and H2O2 as co-substrate. Glutathione levels were measured using a colorimetric assay. RESULTS: Peroxidase activity in cytosolic and CaCl2-extracted (membrane-bound) fractions was inhibited by a specific inhibitor, NaN3. The membrane-bound peroxidase activity was maximal at 12 weeks of gestation while cytosolic peroxidase activity did not change. Placental glutathione content remained unchanged during the first trimester. Decidual and placental peroxidase activities were similar; however decidual glutathione content was 15-fold lower, resulting in a higher decidual peroxidase activity/glutathione ratio (p < 0.03). CONCLUSIONS: We report for the first time that peroxidase may be an important pathway for xenobiotic activation at the maternal-embryonal interface. It remains to be established whether the low glutathione content limits the ability of the decidua but not placenta to protect against genomic damage induced through xenobiotic oxidation.

Calcium Chloride↗