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At least 451 records · Page 25Linked to original sources
PubMed1993

Biochemical and immunological characterization of X-linked ichthyosis.

An immunoquantification protocol based on an enzyme-linked immunosorbent assay was developed to measure the abundance of the microsomal enzyme steroid sulphatase (STS). The two-step sandwich immunoassay is sufficiently sensitive to detect 100-200 pg purified steroid sulphatase in a 50-microliters sample. The steroid sulphatase content in fibroblast, leukocyte and placental extracts correlates with the steroid sulphatase activity in these extracts. No steroid sulphatase protein was found in approximately 350 micrograms plasma proteins from a normal person. In three of four X-linked ichthyosis patients a complete gene deletion was found by Southern hybridization with the full-length STS cDNA as probe. Neither steroid sulphatase protein nor enzymatic activity was found in fibroblast extracts of these three patients. In a fibroblast extract of another X-linked ichthyosis patient, which had a normal Southern blotting pattern, no immunoreactive protein was detected. Residual activity of steroid sulphatase was also not found after prolonged incubation of this fibroblast extract with the natural substrate oestrone sulphate.

Arylsulfatases↗
PubMed1986

Binding of pregnancy-associated plasma protein-A (PAPP-A) to placental subfractions.

Pregnancy-associated plasma protein-A (PAPP-A) has been shown to exert immunosuppressive effects both on complement and on lymphoblastogenesis. It was of interest to see whether this protein could bind to syncytiotrophoblast microvillous membranes since these represent the effective interface between fetal tissue and the immunocompetent mother. Placental subfractions were prepared according to established techniques. PAPP-A was purified from different sources (pregnancy serum and plasma, retroplacental serum, placental extracts) and labelled with radioactive iodine. It could be shown that radioactive PAPP-A, irrespective of its biological origin was primarily binding to brush border membrane preparations but that significant binding was also seen with plasma membrane preparations. The binding was specific since alpha 2-macroglobulin (a structurally related protein to PAPP-A) was unable to displace bound radioactive PAPP-A. Scatchard plot representation of the data indicated that the affinity of PAPP-A for its binding site was of the same order of magnitude as reported for the insulin or GnRH receptors of the trophoblast (Ka 2 10(7)-2.5 10(8) M-1). These results are in agreement with the immunohistochemical localization of PAPP-A on the trophoblast providing that the small binding to plasma membrane preparations is due to contamination.

Cell Membrane↗
PubMed1981

Studies on human phenylalanine Mono-oxygenase. I. Restricted expression.

Enzyme assays for phenylalanine mono-oxygenase have been performed on a variety of non-hepatic human cell types under varying conditions. The cell types studied were cultured fibroblasts, short-term lymphocyte cultures, long-term lymphoblastoid cultures, cultured amniotic fluid cells, hair roots and placental extracts. The cultured cells were assayed after growth under standard conditions and in the presence of a high concentration of substrate, a low concentration of end-product, added hydrocortisone or dexamethasone and under combinations of these conditions. In no instance was a significant enzyme activity obtained.

Amniotic Fluid↗
PubMed1990

A baboon model for pregnancy-associated antigens (PAPP-A, PP5, PP14).

By radioimmunoassays established on human derived antigens, PAPP-A, PP5 and PP14 immunoreactivity was detected in placental extracts and blood of pregnant baboons. None of the serial dilution curves suggested parallelism between respective human and baboon samples. Based on slopes of regressed logit-log transformed binding data, PAPP-A demonstrated the greatest degree of interspecies immunological crossreactivity. PP14 showed the least conservation of antigenic determinants. Physicochemical characterization on heparin, zinc chelate and bovine thrombin affinity matrices could not distinguish human from baboon-derived antigens. As in the human, baboon PAPP-A and PP5 were not detected in blood of male or non-pregnant animals. PP14 was detected in baboon follicular fluid, and only PP5 immunoreactivity was measured in culture media of baboon embryos. Of the three antigens, PAPP-A was detected in pregnant baboons at about 61 days gestation, that is, 4 weeks before PP5 and PP14. With the exception of PP14 which attained peak concentration at 118 days of pregnancy, PAPP-A and PP5 concentrations were greatest at term. In conjunction with physicochemical and immunological criteria, these physiological kinetics clearly support a role for developing a baboon model to serve for further studies into feto-maternal signals, particularly antigens such as PAPP-A and PP5.

Animals↗
PubMed1977

[Aminoacid-p-nitroanilides splitting activities in the mouse human placenta (author's transl)].

Proteolytic activities of human placental extract are determined with the aid of a sensitive micromethod, based upon the Bratton-Marshall-reaction, and aminoacid-p-nitroanilides as substrates. The activities are differentiated by using 19 substrates, by adding 10 effectors, and by incubating the assays within the pH-range from 6.0--8.4. Besides Oxitocinase- and Aminopeptidase-like activities, a very active neutral peptidase, so far unknown in human placenta, an acid peptidase, e.g. Cathepsin C or Dipeptide-aminopeptidase II, and some other enzymes, not yet indentified by us, are demonstrated.

Amino Acids↗
PubMed1975

Resistance to Levamisole (R12456) in heat-stable alkaline phosphatases.

The inhibitory effect of Levamisole (R12456) on human alkaline phosphatases has been studied. At a concentration of 0.1 mM it is possible to differentiate the source of the enzyme. Enzyme activity relatively resistant to Levamisole (less than 20 percent loss) is present in serum with the Regan isoenzyme, in placental extracts, in the intestinal "B" preparation and in heat-stable alkaline phosphatases "unmasked" after treatment at high ionic strength.

Alkaline Phosphatase↗
PubMed1991

Aminopeptidase A in human placenta and pregnant serum.

The activities of serum aminopeptidases (APs) derived from the placenta rise during pregnancy. To confirm the localization of AP-A, which liberates N-terminal acidic amino acids, in placental tissue and to identify it in the serum of pregnant women, chromatographic separation was performed. When a placental extract was subjected to DEAE cellulose column chromatography, the Glu-MCA degradative activity, or AP-A, was separated into two entities. Inhibition testing revealed that the enzyme eluted in Fraction No. 20 from the DEAE-cellulose column consisted of typical AP-A with a molecular weight of approximately 500,000. When the Glu-MCA degradative activity was observed by filtering pregnant serum through HPLC TSK G3000 gel, the activity was found to be due to serum CAP rather than AP-A. What had been thought to be a biochemicophysiological action inherent in blood AP-A raised additional questions.

Aminopeptidases↗
PubMed1990

Do the major human glutathione S-transferases have fatty acid ethyl ester synthase activity?

Two fatty acid ethyl ester (FAEE) synthase isoenzymes purified from human myocardium were reported to be glutathione S-transferases (GST) [(1989) Proc. Natl. Acad. Sci. USA 86, 4470-4473; and (1989) J. Clin. Invest. 84, 1942-1946]. In the present study, the FAEE synthase activity of several purified and well characterized human GSTs were examined with ethanol and [14C]oleic acid as substrates. Three isoenzymes, GST1, GST2 and GST3 which are members of the evolutionary classes mu, alpha, and pi, respectively, were studied and failed to show any significant synthesis of FAEE after 45 min incubation at 37 degrees C. FAEE synthase activity and GST3 activity in human placental extracts can be readily separated by ion exchange chromatography on DEAE cellulose. Thus the results show that FAEE synthase activity is not a feature of the major GSTs found in human tissues. The two FAEE synthase isoenzymes isolated by Bora et al. may have been co-purified with GST isoenzymes or these FAEE synthases may be members of the GST super family that have low specific activity in conventional GST assays and have not been previously described.

Acyltransferases↗
PubMed1987

Interaction with lectin of kappa opioid binding sites solubilized from human placenta.

Kappa opioid binding sites from human placenta, prelabeled with 3H-etorphine and solubilized, were retained on wheat germ agglutinin (WGA) agarose and specifically eluted with N-acetylglucosamine. No significant retention was found with other immobilized lectins, including Concanavalin A (Con A), soybean seed lectin (SBA), Pisum sativum lectin (PsA), Lens culinaris Medik. lectin (LcA), and Lathyrus tingitanus lectin(LtA). About 23% of applied kappa sites were specifically eluted from WGA agarose, less than half of the proportion of rat brain opioid binding sites eluted from the same lectin (55%). Receptors from placental extracts were compared with those from other tissues enriched in either kappa or mu sites. The proportion of applied kappa sites from guinea pig cerebellum eluted specifically from WGA agarose was 36%, whereas elution of binding sites from rat thalamus and rabbit cerebellum (enriched in mu sites) was at a level of 55%. This difference in the level of retention on and elution from WGA may reflect differences in the sugar composition of the glycoproteins of the two types of receptors. Succinylation of WGA abolished its ability to retain opioid binding sites, consistent with involvement of sialic acid. However, currently available evidence suggests that differences in retention on WGA between kappa and mu sites may be due to differences in either sialic acid or N-acetylglucosamine content or both.

Acetylglucosamine↗
PubMed1987

Elevation of plasma 7B2 (a novel pituitary protein) in cord blood at obstetrical delivery and the possible correlation with GH.

Plasma 7B2-immunoreactivity (7B2-IR) concentrations in umbilical artery (UA), umbilical vein (UV) and maternal vein (MV) were measured by RIA at the time of obstetrical delivery at term. Plasma 7B2-IR concentrations (Mean +/- SEM) in UA (N = 12), UV (N = 16) and MV (N = 16) were 725 +/- 69, 699 +/- 64 and 116 +/- 4.5 pg/ml, respectively. Plasma 7B2-IR concentrations in UA and UV were much higher than those in MV. There was no arterio-venous gradient between UA and UV. A trace amount of 7B2-IR (Mean +/- SEM, 226 +/- 16.8 pg/g tissue) was detected in the placental extracts. A statistically significant positive correlation (r = 0.7595, p less than 0.005) was found between plasma 7B2-IR and GH in the UV. Significant negative correlations between body weight of the neonates and plasma levels of GH (r = -0.6836, p less than 0.01) and 7B2-IR (r = -0.4939, p less than 0.05) were also apparent. When analyzing cord blood plasma using gel permeation chromatography and SDS-polyacrylamide gel electrophoresis, a major peak with an apparent molecular weight of 20,000 was observed. These findings suggest that 7B2-IR in UA and UV originates from the fetus and that 7B2-IR does not permeate through the placenta. The possibility of involvement of 7B2 in fetal growth warrants attention.

Chromatography, Gel↗
PubMedDate not supplied

Corticotrophin-releasing hormone production by the placenta and fetal membranes.

Maturation of the fetal hypothalamic-pituitary-axis may be an important factor in the stimulation of the onset of parturition. Recent studies have found that corticotrophin-releasing hormone (CRH), the hypothalamic component of this axis is also present in the placenta and the fetal membranes. We review the evidence demonstrating that glucocorticoids stimulate the production of CRH by these tissues towards term, and this is manifest by increases in CRH concentrations in maternal and fetal plasma and in placental extracts, and by increased abundance of CRH mRNA in the placenta. We discuss how CRH secretion by the placenta and fetal membranes is controlled. We hypothesize that CRH may be an important signal in initiating of the onset and maintenance of term labour and may also be a factor in the etiology of premature labour, through stimulation of the fetal HPA axis, and through paracrine/autocrine interactions within the placenta, fetal membranes and decidua.

Corticotropin-Releasing Hormone↗
PubMed1987

In vitro immunomodulatory effects of placental substances on preparatory MLR and resulting modifications of lymphocyte reactivities.

The immunomodulatory effects of murine placental extracts (PE) were studied in vitro using mixed lymphocyte culture (MLC) and resulting cell-mediated lympholysis (CML). The results showed that preparative cultures in the presence of PE syngeneic to the responding cells led to a low secondary MLR response with a concomitant generation of suppressor cells. At the efferent phase, cells from the same preparative culture showed a weaker cytotoxic activity than controls cultured in the absence of extract. Furthermore, the induction of regulatory cells able to inhibit CTL in vitro activity was also observed. The active substances can be found in the 30% ammonium sulphate precipitate as well as in some gel filtration fractions showing several main bands from 115 to 43 kDa in SDS-PAGE.

Animals↗
PubMed1983

Distribution and metabolism of the teratogen nitrofen (2,4-dichloro-4'-nitro diphenyl ether) in pregnant rats.

Oral exposure of pregnant Long-Evans rats on day 11 of gestation to the teratogen, nitrofen (2,4-dichloro-4'-nitro diphenyl ether), which was uniformly labeled with 14C in the nitrophenyl ring, resulted in the accumulation of radioactivity in maternal fat with lesser amounts found in liver, kidney, other tissues, and in the embryonic compartment. The peak concentration of radioactivity occurred 7-9 h after dosing and the half-life of the label in maternal blood was approximately 8 days. In the embryonic compartment, radioactivity was first detected at 2 h after dosing, peaked at 4-6 h, and declined to half of that initially seen by 24 h. High performance liquid chromatography of embryo-placental extracts revealed 4 metabolites in addition to the parent compound: 4'-amino and 4'-acetylamino derivatives plus 2 hydroxylated derivatives. A similar metabolic profile was observed in maternal blood and liver. In another experiment, purified 4'-amino metabolite was found to have no adverse effect on neonatal survival when administered orally on day 11 of gestation at doses up to 215 mg/kg. These results suggest that the teratogenicity of nitrofen cannot be readily explained by preferential distribution of the compound in the embryo or by a unique profile of stable, extractable metabolites in the embryonic compartment.

Animals↗
PubMedDate not supplied

Conservative treatment of placenta accreta.

Prolonged retained placenta causing a delayed postpartum hemorrhage is a relatively common occurrence. However, there is a dearth of medical literature describing fertility-preserving treatments when standard therapy fails. We present two cases in which protracted retained placenta due to placenta accreta was successfully treated by hysteroscopic resection. Two nulliparous women had spontaneous vaginal deliveries requiring manual placental extraction. Both experienced delayed postpartum hemorrhage and underwent suction curettage with ultrasound guidance. Both patients were found to have persistent products of conception with imaging consistent with placenta accreta. Both patients failed expectant management and subsequently underwent hysteroscopic resection with complete resolution of their symptoms. We conclude that hysteroscopic resection is a conservative therapeutic option for placenta accreta in stable patients.

Adult↗
PubMed1986

Human placental opioid peptides: correlation to the route of delivery.

The levels of opioid peptides in placental extracts were determined by means of a radioreceptor assay with two prototypical opioid ligands, 3H-ethylketocyclazocine and 3H-D-ala2-enkephalinamide. Opioid peptide levels were significantly higher in the placentas obtained by the vaginal route than in those by the abdominal route. The different peptides in the extract were detected by reverse phase high-performance liquid chromatography and a radioreceptor assay for all fractions. The presence of dynorphin-like peptides in several fractions suggests that one or more could be the "natural" ligand of the opioid receptors in the human placenta. A role for these peptides in parturition is a viable possibility.

Animals↗