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At least 631 records · Page 35Linked to original sources
PubMed1980

Placental beta-endorphin-like peptides.

Acid extract of human placental tissue contain, by both radioimmunoassay and radioreceptor assay, beta-endrophin-like material. Half of this material will not go through a 5000-dalton filter and on Sephadex G-200 has a molecular size between 25,00 and 50,000 daltons. Of the material going through a 5000-dalton ultrafilter, 80 percent is excluded on Sephadex G-25 and held back, very slightly, on Bio-Rad P6, indicating a molecular size of approximately 4500 to 4800 daltons. Thus, placenta appears to have macromolecular precursors from which a beta-endorphin-like material is released, with a size approximately 12 amino acids longer than half of the pituitary hormone.

Endorphins↗
PubMed1979

Human placental cell surface antigens:expression by cultured cells of diverse phenotypic origin.

The present work examined the expression of cell surface glycoprotein antigens in cultured human cell lines. The set of glycoproteins studied was defined by their immunoreactivity with antiserum developed to Triton-solubilized extracts of placental brush border membranes. Studies were performed using cell lines of trophoblastic (BeWo, JEG-3) and nontrophoblastic (Chang liver cells) origin, as well as diploid fibroblast cell lines (WI-38, GM-38). Antiplacental brush border antiserum reacts with at least 19 distinct antigens present in placental membrane preparations, each of which can be resolved and identified in two-dimensional electrophoresis. The subunit molecular weight and isoelectric point for all components were defined by their positions in the two-dimensional matrix. Thirteen of these could be detected among the five cell lines examined by lactoperoxidase-catalyzed cell surface iodination. One of these 13 antigens has been identified as the placental isoenzyme of alkaline phosphatase (PAP). The expression of this component is limited to choriocarcinoma cells and Chang liver cells and it is not present in diploid fibroblasts. Under normal circumstances expression of PAP is unique to the differentiated placenta but has been frequently demonstrated in both trophoblastic and nontrophoblastic neoplasms. Two other antigens are variably expressed among the different cell types examined in the present study and their presence or absence was independent of the trophoblastic, epithelial nontrophoblastic, or fibroblastic origin of the cells. Ten surface antigens were expressed in all five cell lines. Six of these had previously been found common to membranes from three adult differentiated tissues, including liver and kidney, as well as placenta (Wada et al, J Supramol Struc 10(3): 287-305, 1979). The presence of this set of antigens in cultured cells as well extends the possibility that these are ubiquitously expressed on human cell surfaces. Two other antigens observed in all cultured cells had been found in both placental and either kidney or liver membranes and may represent common functions shared by many tissues which are also necessary for growth in vitro. The two remaining placental antigens seen in all cultured cells have previously been shown to be absent in adult tissues. Their presence in cultured cells but not in the membranes of resting differentiated tissues may signify the expression of glycoproteins characteristic of trophoblasts in all cells adapted to growth in culture.

Alkaline Phosphatase↗
PubMed1998

The role of deoxyribonuclease I in amniotic fluid during pregnancy and labour.

The purpose of this study was to detect the presence, and determine the normal values and the significance of DNase I in the amniotic fluid and in human placentas. Fifty-one pregnant women at 16-22 weeks of gestation and 89 women in spontaneous labour at term were recruited to the study. DNase I activity was measured in amniotic fluid and cytoplasmic extracts from the fetal portion of placentas by using a spectrophotometric technique (DNA precipitation assay) and nucleic acid electrophoresis, following degradation of the DNA by the enzyme. DNase I activity was undetectable in the placental cytoplasmic extracts. In the second trimester of pregnancy DNase I activity was detectable in amniotic fluid (2.3+/-0.64x10(5) U/l). During labour DNase I activity was also detectable, but reduced levels were observed in the presence of clear amniotic fluid, compared to second trimester levels, (1.9+/-0.44x10(5) U/l, P<0.001), whereas higher levels were found in the presence of meconium-stained amniotic fluid compared to both second trimester and clear amniotic fluid at labour (11.4+/-4.1x10(5) U/l, P<0.001 and P<0.001, respectively). Three out of 17 fetuses with meconium-stained amniotic fluid (18%) developed perinatal infection. In conclusion, the detection of DNase I activity in the amniotic fluid of second and third trimester indicates a physiological role in human pregnancy. DNase I activity normally decreases at term, compared to second trimester levels, but increases significantly in the presence of meconium.

Amniotic Fluid↗
PubMed1990

Measurement of parathyroid hormone-related protein in extracts of fetal parathyroid glands and placental membranes.

A radioimmunoassay based on an antiserum to human parathyroid hormone-related protein PTHrP(1-16) was used with PTHrP(1-34) standard to measure the concentration of immunoreactive PTHrP in extracts of fetal parathyroid glands from lambs and calves and also placental membranes obtained from several species, including man. Dilution curves from these sources were parallel to those obtained for PTHrP(1-34) standard. It was demonstrated that this parallelism was not the result of tracer damage caused by enzymic activity in the tissue extracts. Extracts of human placental membranes were subjected to high-pressure liquid chromatography with a linear acetonitrile gradient. Co-elution of cytochemical biological activity with 125I-labelled PTHrP(1-34) was noted. These results provide further evidence for both the fetal parathyroid glands and the placenta containing material resembling PTHrP which may be responsible for sustaining the activity of the placental calcium pump which maintains the fetus hypercalcaemic relative to its mother.

Animals↗
PubMed1996

Characterization and quantitation of the active polynucleotide fraction (PDRN) from human placenta, a tissue repair stimulating agent.

The polydeoxyribonucleotide (PDRN) fraction is an extract which forms the active component in a new formulation of the drug Placentex (a tissue repair stimulating agent), obtained from human placenta through an original proprietory extraction method. From a comparison of the UV, NMR and IR spectra of this fraction (before and after nuclease treatment) with that of a similar standard (Sigma D1501), it was shown that the active substances in the PDRN fraction mainly consist of a mixture of DNA fragments. By gel electrophoresis, the molecular weights of the DNA fragments were shown to range from 50 to 2000 base pairs. Finally, an HPLC method is described, based on an anion-exchange material capable of determining the amount of PDRN in different batches of the extract, which varied from 80 to 90%.

Chromatography, High Pressure Liquid↗