SEARCH · PubMed Health
Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
JC human papovavirus was found to replicate in primary human amnion cells. The virus has undergone eight passages in amnion cells and was identified by serological methods as JC virus. By restriction endonuclease analysis of the viral DNA, the fragments observed were identical to those previously reported for the prototype strain.
Sixteen established cell lines of simian virus 40 (SV40)-transformed human amnion cells were examined for SV40 production. Many of these lines produced SV40 for extensive periods. Virus production had not ceased for 2 lines after 18 months, for 3 lines after 12 months, and for 3 lines at 3 months after recovery from "crisis". Three lines became virus-free in the first month, 1 line in the second month, 1 in the third month, and 1 in the fourth month, and 2 lines stopped virus production between 6 and 11 months after recovery. The virus titers were relatively low. Inclusion body-containing cells were infrequent. In contrast, in most cultures of SV40-transformed human fibroblasts rescued from crisis, no infectious virus was demonstrated, although exceptions have been reported. Virus was produced after heterokaryon formation of cells of the virus-free amnion lines with CV-1 cells in the presence of inactivated Sendai virus, as observed for SV40-transformed human fibroblasts. During the crisis period, some of the SV40-transformed amnion cells produced substantial amounts of virus. Titers decreased during the later periods of crisis. The most pronounced decrease in titers was in cultures from which established lines were recovered.
Human cytomegalovirus (CMV), known to replicate in vitro in human fibroblastic cells, was found to replicate in epithelial human amnion (HA) cells. Large syncytia formed in these cells after infection with CMV; inclusion bodies were observed in the nuclei, and CMV antigens were demonstrated in both the cytoplasm and the nucleus by indirect immunofluorescence techniques. The synthesis of virus DNA was also detected, and the production of infectious virus was followed. The titers were lower (from 10(4) to 6 X 10(5) using different isolates of CMV) than those obtained in human embryo fibroblast (HEF) cells, and the replication cycle was slower in HA than in HEF cells.
It was found that a human hepatoma-associated ALP (orthophosphoric monoester phosphohydrolase, E.C. 3.1.3.1) shared electrophoretic mobility, inactivation by urea, inhibition by inorganic phosphate, ethylenediaminetetraacetate, and amino acids (L-phenylalanine, L-leucine and L-homoarginine), heat stability, sensitivity to neuraminidase, pH optimum, Km value, and antigen site with fast moving ALP isozymes of FL cell strain derived from human amniotic membrane. However, 40-week-old fresh amniotic membrane lacked this isozyme. Instead, it had a placental type ALP consisting of minor components. The other ALP isozyme of FL cells had properties common to hepatoma ALP with regard to L-phenylalanine sensitivity, inhibition by ethylenediaminetetraacetate, inactivation by urea, and antigen site, but differed from it in electrophoretic mobility, sensitivity to L-leucine and L-homoarginine, and the presence of another antigen site. It was more heat stable and more sensitive to inhibition by inorganic phosphate than Hepatoma AP. The possible regulatory mechanism between the hepatoma-type ALP and the placental type ALP in the amnion cells is considered.
The ultrastructure of the surface of primary human amnion monolayer cells undergoing cytopathology induced by Clostridium difficile toxin was examined by scanning electron microscopy. Our observations indicated that the type and distribution of cell surface projections were altered dramatically by this toxin. The patterns of such surface changes were specific for the two different types of cells found in this cell culture. Cells with demarcated borders showed rearrangement of microvilli into globular chains or ridges which lined up with the branching membrane. Cells without demarcated borders exhibited studlike microvilli, all arranged into ridges or globular chains. These changes were noted after 1 h of toxin exposure and persisted without further progression, in spite of continued toxin exposure, up to 48 h. These data indicate that C. difficile produces a cytolytic toxin and that scanning electron microscopy may be useful in determining toxin-cell interactions.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Primary human amnion cell monolayers which had been treated with DEAE-dextran, washed, and then inoculated with sonicated cells of the EB3 line of Burkitt's lymphoma cells developed foci of transformed amnion cells 7 to 14 days later. When either the DEAE-dextran or the sonicate was omitted, no significant transformation was found. The foci consisted of enlarging mounds of rapidly dividing cells, which upon subculturing continued their high miotic activity; and strains or lines of the transformed amnion cells were thus readily established. The modal number of chromosomes in such lines was 65 instead of the normal 46. Not all human amnions yielded cells transformable by EB3 cell sonicate, as determined by direct comparisions using the same cultural conditions and testing with the same fresh sonicate preparation in the same experiment. Overall, it appeared that only about 40 to 50% of the amnions yielded transformable cell monolayers; the rest gave monolayers apprently completely refractory to the transformation. The transformed amnion cells contained nuclear and cytoplasmic Epstein-Barr virus (EBV) antigen(s), as revealed by indirect immunofluorescence tests. EB3 cell sonicate also caused the appearance of rapidly growing transformed cell foci on secondary rat embryo cell monolayers which had been sensitized with DEAE-dextran. Calcium in the cell maintenance medium decreased the number of transformed foci found, both on the human and on the rat cell monlayers. Sonicates of cultured normal human leucocytes had no such transforming activity for either the human or the rat cells. The transforming agent in EB3 cell sonicate was completely destructible by either deoxyribonuclease or trypsin, but not by ribonuclease, and was not neutralizable by anti-EBV serum. The simplest interpretation of these results is that the transforming agent is part of all of the EBV DNA plus some necessary protein, with both the DNA and the protein accessible to hydrolytic enzyme action.
Vesicular stomatitis virus forms discrete, microscopic plaques in stationary cultures of the WISH amnion cell line. Microplaque formation is rapid, reproducible, and easily quantitated, occurs at temperatures ranging from 33 to 40 degrees C, and does not require a semisolid overlay. WISH cells, however, are less sensitive to vesicular stomatitis virus than are chicken embryo, 3T6, or Vero cells. WISH amnion cells also are highly sensitive to the antiviral effects of human interferon, and a quantitative human interferon assay, based on vesicular stomatitis virus plaque reduction in WISH cells, is described. This interferon assay can be performed within 1 day, uses a liquid overlay medium, does not require a vital stain, is as sensitive as other methods that use diploid cell strains, and is performed in a microtiter system.
Hypotonic treatment of amnion fluid cell-nuclei was found to enhance demonstration of Y chromatin and of autosomal fluorescence in interphase cell-nuclei following quinacrine mustard staining. In contrast, visualization of the Barr body was not improved by this treatment. Nuclear sex determination on cellular material from 200 samples of amniotic fluid was unequivocal in 197 cases; in only 3 cases were the findings uncertain. There were no erroneous determinations. In one instance maternal cellular tissue was observed in smear preparations. Nuclear sex determination presents a simple method of supplementing and substantiating prenatal chromosomal diagnosis.
Neutralizing antibodies were raised in mice that had been inoculated repeatedly with moderate quantities of human leukocyte interferon highly purified by affinity chromatography on immobilized anti-interferon globulins. Interferon preparations of lesser purity sensitized the mice to subsequent inoculations of interferon and almost invariably caused death before anti-interferon titers developed. Antibody-purified interferon stabilized by sodium dodecyl sulfate was a superior antigen to interferon that had received mouse serum albumin as an additive. The amount of antibody could be augmented by experimental induction of ascites. The antibodies specifically neutralized leukocyte and lymphoblastoid interferons but not those interferons obtained cultures of human foreskin fibroblasts, embryonic kidney cells, and amnion cells.
Early increase in RNA synthesis induced in human amnion U cells by infection with poliovirus is accompanied by an increased incorporation of amino acids into non-histone nuclear proteins with an approximate molecular weight of 40 000. These proteins are the main polypeptides of the 30-S nuclear ribonucleoprotein particles. After fractionation of nuclear proteins by extraction with solutions of different ionic strength, these polypeptides are present in the fraction of nuclear sap proteins soluble in 0.1 M Tris - HCl buffer, pH 7.6, and in the fraction of non-histone chromosomal proteins which are soluble in 0.35 M NaCl. The increase in synthesis of non-histone nuclear proteins with an approximate molecular weight of 40 000, observed in the infected cells, represents an increase in the synthesis of proteins concerned with post-transcriptional events and, therefore, is the result and not the cause of gene activation.
The receptor specificity of the plant seed toxin ricin, which ordinarily binds to galactose-containing receptors, has been altered by coupling monophosphopentamannose residues to ricin by reductive amination and by reversibly binding lactose to the modified ricin. The added monophosphopentamannose residues provide ricin with the recognition factor common to fibroblast lysosomal hydrolases and enable the modified ricin (Man6P-ricin) to bind to the fibroblast Man6P receptor and inhibit protein synthesis in the cells via this receptor. The addition of lactose to Man6P-ricin saturates the galactose site on Man6P-ricin and prevents the binding of Man6P-ricin to cells via galactose-containing ricin receptors. The Man6P receptor-mediated toxicity of Man6P-ricin, identified in human fibroblasts by competition by Man6P and blockade by alkaline phosphatase treatment, was not detected in HeLa cells or human amnion cells. Consequently, in the presence of lactose, the fibroblasts were 8 and 13 times more sensitive than amnion and HeLa cells, respectively. These results show that highly toxic cell-type-specific reagents can be made by the proper alteration of toxin receptor specificities. An attempt to construct a highly toxic altered toxin by adding Man6P residues to diphtheria toxin fragment A was unsuccessful. A possible explanation is that in Man6P-ricin the ricin B chain performs some entry function, even though the initial binding step occurs at the Man6P receptor.
1. Control human sera had no effect on human amnion cell culture. 2. The sera from nineteen of twenty-one patients with ulcerative colitis had a marked cytopathic effect on cell cultures, suggesting an autoimmune effect. The sera of three of these showed an additional cytopathic effect on human amnion cell culture, suggesting a viral-like quality. 3. The sera from patients after total colectomy and protectomy for ulcerative colitis had no effect on cell cultures. 4. Rabbit antisera did not produce demonstrable antibodies or protect against the cytopathic effect in cell culture.
About 40 of the genetically induced metabolic defects in humans which are known today can be diagnosed prenatally. The diagnosis of some diseases is possible from the amnionic liquor itself or from uncultivated amnion cells. But in many cases it is necessary to perform the tests for prenatal diagnosis of a biochemical defect with cultivated amnion cells. Of the numerous test procedures, 4 methods, different in principle, will be described here. They all permit a reliable prenatal diagnosis with a minimum of time and cell material.
The effect of human leukocyte interferon on the cytoplasma membrane of cultured homologous cells has been investigated. U-amnion cells were labelled with (1-14C) alpha-aminoisobutyric acid (AIB), a low-molecular-weight non-metabolizable amino acid. Following uptake, the AIB is released spontaneously from the cells. Treatment of cells with interferon reduced the AIB release. This effect was dosedependent, was neutralized by anti-interferon serum and was strongly reduced by trypsin treatment.
U cells (a permanent, human amnion cell line) were protected against infection with Semliki Forest Virus (SFV) by human interferon (HIF) from peripheral leukocytes. Despite the usual genus-specific action of interferons, mouse L929 cultures (a permanent mouse fibroblast cell line) were also protected by HIF. The antiviral action of HIF in six other primate cell cultures was also examined. It is of interest that two lymphoblastoid cell lines, RPMI1788 and Kaplan, were insensitive to HIF. The sensitivity of ten different viruses against HIF in primary African green monkey kidney cell cultures was compared. Among the viruses tested SFV was the most sensitive whereas two strains of vaccinia virus were barely inhibited. In contrast, type 1 herpes simplex virus was relatively sensitive to the action of HIF.
In HEp-2 and amnion cell cultures infected with type 1 adenovirus the DNase activity of cell extracts was measured on 32P-labelled Escherichia coli DNA substrate. Enzyme activity was demonstrated by the acid soluble nucleotides released from the 32P-DNA and by the decreased sedimentation rate of labelled DNA. High DNase activity was measured in both adenovirus infected and in untreated HEp-2 cell extracts. Nuclease activity of the amnion host cells being much lower than that of HEp-2 cells, virus-associated endonuclease activity was successfully demonstrated in them. Purified type 1 adenovirus decreased the sedimentation rate of 32P-labelled E. coli DNA. The phenomenon is explained by the virion-associated endonuclease activity. Trypsin inactivated and anti HEp-2 IgG failed to inhibit the virion nuclease. An association between endonuclease and trypsin sensitive penton is assumed.