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At least 739 records · Page 41Linked to original sources
PubMed1987

A 5'----3' exoribonuclease of human placental nuclei: purification and substrate specificity.

An exoribonuclease that hydrolyzes single-stranded RNA by a 5'----3' mode yielding 5'-mononucleotides has been purified from human placental nuclei. Chromatographic studies of crude placental nuclear extracts suggest that the enzyme is a relatively abundant nuclear RNase. Poly(A) is degraded by a processive mechanism while rRNA is degraded in a partially non-processive manner, possibly because of its secondary structure. The enzyme has an apparent molecular weight of 113,000, derived from determinations of the Stokes radius (43 A) and sedimentation coefficient (6.3 S). Substrates with 5'-phosphomonoester end groups are 10-20 times better than 5'-dephosphorylated substrates. The locale of the enzyme in nuclei of normal human cells as well as its mode of action suggest a role in nuclear RNA processing or turnover.

Cell Nucleus↗
PubMed1988

Pregnancy-specific beta 1 glycoprotein in rat: tissue distribution of the mRNA and identification of testicular cDNA clones.

A partial cDNA of pregnancy-specific beta 1 glycoprotein isolated from human term placenta was used as probe for slot-blot analysis of total RNA extracted from placental and non-placental tissues in the rat. RNA hybridization with the probe was observed in rat placenta, indicating the presence of mRNA highly homologous to human SP1. The quantity of hybridizing RNA increased with increasing gestational age. In non-pregnant rats, SP1-hybridizing mRNAs were found in uterus, intestine and testis, while no hybridizing material was detected in liver or muscle. The amount of rat SP1 mRNA, based on percentage of total tissue RNA, was greatest in the testis followed by intestine, uterus and placenta. Using the same probe, six clones were obtained by screening a rat testis cDNA library. These clones carried cDNA inserts ranging in size from 1530 to 1983 bp. An internal EcoRI site was present in all cDNA clones. Southern blot analysis confirmed that the cDNA insert of all the clones was homologous to human placental SP1 cDNA. These results suggest a possible origin for the trace quantities of SP1 detected in non-pregnant individuals. It also confirms that the rat is an appropriate model for studying the physiological functions of SP1.

Animals↗
PubMed2001

Canine relaxin-like factor: unique molecular structure and differential expression within reproductive tissues of the dog.

Employing postpubertal testicular tissue, we determined the cDNA coding sequence of a truncated canine relaxin-like factor (RLF) consisting of a signal peptide of 28 amino acids (aa), a B-domain of 23 aa, a truncated C-domain of 34 aa, and an A domain of 26 aa, respectively. Within the B-domain of canine RLF, the putative relaxin receptor binding motif contained a single substitution with the C-terminal arginine replaced by a serine residue, and the putative RLF receptor binding motif was truncated. Leydig cells specifically expressed RLF in the normal postpubertal and cryptochid testis as well as in testicular Leydig cell adenoma. The epididymis was an additional source of RLF in the dog. In the female reproductive tract, expression of immunoreactive RLF and relaxin were compared. Within the ovary, RLF, but not relaxin, was detected in follicular theca interna and granulosa cells and the corpus luteum. In the nonpregnant uterus, luminal and glandular epithelium coexpressed RLF and relaxin. Uteroplacental tissue at early stages of gestation revealed RLF expression in the proliferative fetal villous cytotrophoblast and in maternal uterine cells. In the mature canine placenta, the trophoblast surrounding the maternal blood vessels and the hemophagous cytotrophoblast of the paraplacental zone expressed RLF. Canine relaxin was absent in the paraplacental areas. Western analysis of placental tissue extracts revealed the presence of specific immunoreactive bands likely resembling unprocessed and enzymatically cleaved RLF. Differential expression of RLF and relaxin appears to reflect distinct autocrine and paracrine functions of RLF in canine reproductive tissues.

Amino Acid Sequence↗
PubMed1979

Inhibition of lymphocyte cytotoxicity and mitogen-induced transformation of lymphocytes by human skin homogenates.

Limitation of the inflammatory cascade has been demonstrated in man by an inhibitor(s) of the prostaglandin system and by inhibitor(s) for chemotaxis of leukocytes. Other factors may exist in vivo that inhibit other inflammatory sequences. In this report, homogenates from human skin interfered with 2 standard assays of lymphocyte function, mitogen-induced transformation and cytotoxicity while homogenates of human placenta did not. Differential centrifugation studies located inhibitory factor(s) primarily in the nuclear fractions. Therefore, reversible transitory depressions of the cell-mediated immune response that are observed concomitantly with chronic dermatoses may reflect release of inhibitory material dermatitic skin in vivo.

Cytotoxicity, Immunologic↗
PubMed1982

Soluble HLA antigens in normal human immunoglobulin preparations.

Nine lots of normal human immunoglobulin produced in Bulgaria and India, prepared from venous or placental blood, were assayed for the presence of HLA antigens by the inhibition of cytotoxicity of HLA alloantisera using two different absorption procedures. The results indicate that the normal human immunoglobulin preparations tested here contain soluble HLA antigens as demonstrated by the inhibition of HLA alloantisera. Most of the higher frequency antigens of the HLA-A, B, C and DR locus appear to be present in the Ig-preparations. In samples from India there appears to be a lack of HLA-A3 antigen, which corresponds to the low frequency of A3 in this population. Immunoglobulins produced from different raw materials contain different amounts of soluble HLA antigens.

Absorption↗
PubMed1998

Incidence of rat-soluble placental factors on IgE and IgG2a synthesis.

PROBLEM: The in vivo effect of soluble factors present in placental culture supernatants (PCSs) on the synthesis of rat immunoglobulin E (IgE) and IgG2a isotypes was investigated. METHOD OF STUDY: Batches of Wistar SPF rats immunized with a 10-microgram dose of ovalbumin and Al(OH)3 were used: group I, consisted of virgin rats; group II, virgin females injected simultaneously with PCSs; and group III, pregnant females. As controls, nonimmunized batches were included. Serum samples were collected at days 0 (basal) and 10 after antigen challenge, determining levels of total and specific antiovalbumin of both IgE and IgG2a by enzyme-linked immunoadsorbent assay (ELISA). RESULTS: In vivo and at least at the doses administered, PCSs exert an inhibitory effect on the synthesis of specific and total anti-ovalbumin IgE during the course of immune response to such challenge. However, PCSs did not modify serum values of total and specific IgG2a. CONCLUSIONS: These results suggest that PCSs exert selective influence on the synthesis of diverse immunoglobulin isotypes during immune response, through the balance of cytokines synthesized by placental cells.

Animals↗