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Biomedical subjects

G Florent

Publications and source records attributed to G Florent.

At least 19 recordsLinked to original sources
PubMed1990

An IgM specific ELISA for the serodiagnosis of viral bovine respiratory infections.

A capture ELISA for the detection of IgM antibodies to Infectious Bovine Rhinotracheitis (IBR) and to Bovine Respiratory Syncytial (BRS) viruses was developed. In these assays, the first monoclonal antibody to bovine IgM is used as the catching antibody while the second monoclonal detects specific antiviral antibodies. The test was evaluated on serum samples originating from both experimentally and naturally infected animals. From these studies, it has been shown that primary IBR and BRS virus infections can be confirmed using serum samples collected 5-10 days after the appearance of the clinical signs of disease.

Animals↗
PubMed1988

Modulation of the urokinase receptor in human colon cell lines by N,N-dimethylformamide.

The present study documents the effect of the planar, polar differentiation promoter N,N-dimethylformamide (DMF) on urokinase binding to colon carcinoma cells. Exposure of the colon carcinoma cell lines to the agent resulted in enhanced specific binding of radioactive urokinase to all cells tested. Insulin binding to the cells was, however, unaffected by DMF. A DMF exposure period of 45 h was required to observe maximum urokinase binding to two representative cell lines FET and RKO. Optimal stimulation of both cell lines occurred with 0.8% DMF. Scatchard analysis revealed the dissociation constants to be unchanged by the agent with the increased binding of radioactive plasminogen activator reflecting an up-regulation of binding sites. In this regard, the cell line RKO upon exposure to DMF, displayed approx. 700,000 receptors/cell, the highest value published, to date, for any cell line.

Cell Line↗
PubMed1988

Determination of the levels of urokinase and its receptor in human colon carcinoma cell lines.

At present, there is a lack of availability of differentiation markers for colon carcinoma. This may, in part, be a consequence of the diversified function of the normal human colon. This study addresses the possibility that the expression of urokinase and its receptor is inversely related to differentiation in colon carcinoma. Six colon carcinoma cell lines including three well-differentiated (CBS, GEO, FET) and three poorly differentiated ones (HCT116, HCT116b, RKO) were screened for urokinase receptor display and secretion of the plasminogen activator. A radioreceptor assay was used to determine receptor levels. Binding of radioactive urokinase to colon cells was saturable, specific, and time dependent. Cell-bound 125I-labeled protease was unaffected by the presence of epidermal growth factor, low-molecular-weight urokinase, plasminogen, or transferrin. Time course studies revealed that maximum amounts of radioactive tracer were bound in a 30-min period with no change occurring over the course of a 90-min incubation. Scatchard analysis of ligand binding indicated that the well-and poorly differentiated cells could be separated on the basis of receptor display; the aggressive RKO, HCT116, and HCT116b expressed in excess of 10(5) sites per cell, while the more indolent CBS, GEO, and FET possessed less than 1.5 X 10(4) receptors per cell. The colon carcinoma cells were also analyzed for urokinase in the conditioned medium. Low levels of the plasminogen activator (0.8 to 1.3 ng/ml/10(6) cells/72 h) were associated with the more "mature" cells. This was in contrast to the elevated levels of the protease (3.9 to 11.4 ng/ml/10(6) cells/72 h) present in the medium derived from the more aggressive cells (HCT 116, HCT116b, RKO). Thus, secreted urokinase and/or the expression of cellular receptor for the plasminogen activator may provide useful measurements of the degree of undifferentiation of in vitro colon carcinoma.

Binding, Competitive↗
PubMed1988

Alterations of the biological characteristics of a colon carcinoma cell line by colon-derived substrata material.

This study documents the ability of substrata material derived from well but not poorly differentiated colon carcinoma cells to alter the biological characteristics of a separate colon carcinoma cell line (MOSERSF). To assess changes induced by the presence of these substrata, MOSERSF cells were screened for (a) morphological features, (b) secretion of carcinoembryonic antigen (CEA), (c) alteration of urokinase levels, and (d) sensitivity to the growth-inhibitory peptide transforming growth factor beta. Morphologically, MOSERSF cells grown on plastic displayed a rounded shape and could be detached by agitation. Subculturing of these cells onto substrata laid down by well differentiated (mature) colon carcinoma cells resulted in cell attachment and spreading. These changes did not manifest themselves when cells were plated on material derived from poorly differentiated (primitive) colon cells. Conditioned medium from MOSERSF cells grown on plastic or on colon-derived material from the well and poorly differentiated colon cells were compared for CEA levels. Substrata derived from undifferentiated cells were without effect on assayable CEA (substrata absent, 1.4 ng/ml/10(6) cells/72 h; substrata present, 1.4-1.7 ng/ml/10(6) cells/72 h). However, growth of MOSERSF cells on material deposited by well differentiated colon cells resulted in a 3-fold increase in the level of CEA. Spent medium was also analyzed for urokinase. A high level of the protease (20.3 ng/ml/10(6) cells/72 h) was expressed by MOSERSF cells. The concentration of the enzyme was reduced by over 50% when MOSERSF cells were propagated on substrata laid down by well differentiated cells. An enhanced sensitivity to the growth-retarding effects of transforming growth factor beta was seen with certain substrata. On plastic, transforming growth factor beta inhibited proliferation of MOSERSF cells with a median effective concentration of 0.65 ng/ml. However, on substrata from mature but not primitive cells, MOSERSF cells exhibited an increased sensitivity to the peptide (median effective concentration, 0.16 ng/ml). Colon-derived material obtained from both well differentiated and poorly differentiated colon carcinoma cells was compared after [35S]-methionine metabolic labeling. More [35S]methionine was incorporated into the material from the "mature" colon cells. The substrata could also be distinguished by quantitative differences in a number of high molecular weight proteins. Immunofluorescence of colon-deposited material revealed the presence of laminin and fibronectin.

Carcinoembryonic Antigen↗
PubMed1988

Alteration in the behavior of a colon carcinoma cell line by extracellular matrix components.

It was previously demonstrated that substrata derived from well differentiated colon carcinoma cell lines induced a more benign program in a separate malignant colon cell line, MOSERsf. This study attempts to define a role for extracellular matrix components in the biological events of MOSERsf cells. Alterations in morphology, secreted carcinoembryonic antigen (CEA) and urokinase brought about by individual components were determined. Laminin induced similar changes to colon-derived substrata in that there was increased cell attachment and spreading, a 4-fold elevation in CEA and a 45% reduction in urokinase. Fibronectin stimulated cell attachment without altered morphology and reduced the amount of plasminogen activator. CEA values, however, remained unchanged. Growth of MOSERsf cells on all types of collagen failed to elicit any change in cell shape or CEA. However, type I/III collagen raised urokinase levels by 40%. Transforming growth factor beta (TGF-beta) induces cellular laminin and fibronectin, promotes cell attachment, and spreading, elevates CEA and diminishes urokinase. These data argue for a role for laminin and possibly fibronectin in the governing of biological events culminating in a more mature colon cell.

Carcinoembryonic Antigen↗
PubMed1988

Detection of antibodies to bovine leukemia virus in bovine milk samples with an ELISA involving two monoclonal antibodies.

An indirect enzyme-linked immunosorbent assay was used to detect antibody to bovine leukemia virus (BLV). In the assay the gp51 antigen was selectively adsorbed to the solid phase using a monoclonal capture antibody. Specific antibodies in milk or serum samples were revealed by the addition of a monoclonal antibovine IgG 1 conjugated to peroxidase. All milk samples from animals found positive by serum testing were shown to be positive. BLV-positive milk samples were detected when added to pools of negative samples.

Animals↗
PubMed1986

Enzyme linked immunosorbent assay used to monitor serum antibodies to bovine respiratory disease viruses.

An enzyme linked immunosorbent assay (ELISA) was applied to the detection of serum antibodies against infectious bovine rhinotracheitis (IBR), parainfluenza-3 (PI3), adenovirus type 3 (adeno 3) and bovine respiratory syncytial (BRS) viruses. Paired serum samples from calves vaccinated with live attenuated virus vaccines were tested. The ELISA compared favorably with the virus neutralization test for detecting serologic responses to IBR, BRS, and adeno 3 viruses or with the hemagglutination inhibition test for PI3 virus. The simplicity, sensitivity and rapidity of the ELISA test makes it a useful tool for immunological studies with respiratory viruses.

Adenoviridae↗
PubMed1984

Clinical evaluation of a temperature-sensitive bovine viral diarrhea vaccine strain.

A naturally occurring strain of bovine viral diarrhea (BVD) virus was chemically treated to produce a genetically stable, temperature-sensitive mutant, designated RIT 4350. The RIT 4350 strain had a restrictive growth temperature of 39.5 C, so that systemic replication or fetal infection was not detected after parenteral administration in cattle. The RIT 4350 strain was tested as a cell culture-adapted vaccine in healthy heifers, immunodepressed calves, and pregnant cows. In a pathogenicity test in 5 healthy heifers, vaccination with 10 times the field dose resulted in seroconversion, but produced no clinical signs of disease or leukopenia. In a pathogenicity test in immunodepressed calves, 7 test animals were treated with dexamethasone and inoculated with 10 times the field dose. The calves developed mild enteric signs, but virus isolation attempts were negative. Following vaccination, the immunodepressed vaccinated calves were challenge exposed with the Osloss strain of BVD virus; all these vaccinated calves remained healthy. Two of 68 postchallenge serum samples from vaccinated calves were positive for BVD virus, compared with 9 of 20 samples from control calves. In another pathogenicity test, 7 pregnant cows vaccinated with 4 times the field dose seroconverted, remained clinically healthy, and delivered healthy calves.

Animals↗
PubMed1983

Evaluation in young children of the Urabe Am 9 strain of live attenuated mumps vaccine in comparison with the Jeryl Lynn strain.

Urabe Am 9, a new strain of mumps vaccine, originally developed in Japan, was evaluated in children 14 to 20 months of age in a comparative trial with the Jeryl Lynn strain. Both vaccines performed well. The antibody responses were measured using a neutralization test and a haemolysis-in-gel test. The seroconversion rates at six weeks, as detected with either one or both tests, were 55/58 (94.8%) after the Urabe Am 9 and 58/60 (96.7%) after the Jeryl Lynn vaccine. Only mild infrequent adverse reactions were observed. It is concluded that both strains of live attenuated mumps vaccine are immunogenic and well-tolerated in this age group.

Antibodies, Viral↗
PubMed1983

Comparison of the Urabe Am 9-Schwarz and Jeryl Lynn-Moraten combinations of mumps-measles vaccines in young children.

Two mumps-measles vaccine combinations were evaluated for their reactogenicity and immunogenicity in children aged 14 to 20 months. The Urabe Am 9-Schwarz combination vaccine was given to 108 double seronegative children. The seroconversion rate at six weeks after vaccination was 99.1% for measles (haemagglutination-inhibition test) and 92.6% for mumps (neutralization and haemolysis-in-gel tests). The Jeryl Lynn-Moraten vaccine was administered to 85 double seronegative children; the seroconversion rates were 95.3% for measles and 83.5% for mumps. The reported post-vaccination signs and symptoms resembled those seen after monovalent measles vaccine but were more accentuated. Fever over 37.5 C degrees was reported in 66.7% and unusual restlessness and irritability in 68.5% of the Urabe Am 9-Schwarz double seronegative vaccines compared to 55.3% (p less than 0.05) and 54.1% (p less than 0.05), respectively, in the recipients of the Jeryl Lynn-Moraten vaccine. These relatively high reaction rates probably reflect the close observation of the children by their parents during the study. Nevertheless, the tendency towards increased reaction rate and, possibly, reduced immunogenicity of bivalent mumps-measles vaccines as compared to the corresponding single vaccines should be taken into account in the planning of large scale vaccination of young children.

Antibodies, Viral↗
PubMed1981

Decrease of the lymphoproliferative response to varicella-zoster virus antigen in the aged.

Humoral antibodies and specific cellular immune reactions (proliferative immune response in the lymphocyte transformation test) to varicella-zoster virus antigen were measured in children, young adults, and elderly people. In children and young adults, the humoral varicella-zoster-specific antibodies and the virus-specific cellular immune response generally coincided. In the over-60 age group, however, a discrepancy was often observed between these parameters. Ninety percent of the elderly subjects showed humoral antibodies, but only 64% still had a measurable varicella-zoster-specific immune response. There was no correlation between the magnitude of the virus antigen-specific immune response and the mitogen-induced lymphoproliferative response (phytohemagglutinin stimulation). One in three elderly people, therefore, showed no cellular immune response to the varicella-zoster virus antigen, and this person could probably be regarded as a potential herpes zoster patient.

Adolescent↗
PubMed1979

Genotypic characterization and clinical evaluation of an influenza A/Texas/1/77 (H3N2)-like recombinant: RIT 4199.

The RIT 4199 (H3N2) strain was obtained by recombination of PR/8/34 (H0N1) and A/Alaska/5/77 (H3N2) isolates. Its genetic composition was determined by RNA-RNA hybridization and by identification by gel electrophoresis of the double-standard RNA formed. The RIT 4199 was inoculated intranasally to 27 seronegative volunteers at a dose of 10(7.3)EID50. The results show that it is suitable for live vaccine strain.

Adult↗