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Biomedical subjects

G Dorval

Publications and source records attributed to G Dorval.

At least 19 recordsLinked to original sources
PubMed1979

Immunofluorescence assay for antinuclear factor: a nonspecific test in hospitalized medical patients.

Serum from 149 randomly selected hospitalized medical patients was tested for the presence of antinuclear factor (ANF) by the conventional immunofluorescence technique. Patients with positive and negative results were then compared as to clinical history, particularly previous drug exposure, physical findings, and levels of C-reactive protein and immune complexes in the serum. The frequency of ANF positivity was found to be very high (23%). Although the presence of ANF was significantly correlated (P less than 0.02) with a higher age, it was not significantly related to any other clinical or laboratory feature assessed. It was concluded that ANF testing cannot serve as a blind diagnostic screening tool for connective tissue diseases because of its nonspecificity.

Adolescent↗
PubMed1979

Comparative studies on the expression of Fc-receptors, Ia antigens, and beta 2-microglobulin following in vitro herpes simplex virus infection of human lymphoid cells.

Characteristics of the specificity and affinity of surface Fc-receptors induced on Raji (a Burkitt's lymphoma derived B cell line) and Molt-4 (a T cell line derived from a leukaemic patient) after herpes simplex virus (HSV) infection were studied, together with the expression of other surface markers. Inhibition experiments of EA-rosetting suggested that Raji cells infected by HSV had a higher affinity for soluble aggregated IgG than for IgG serologically adsorbed onto erythrocytes; an opposite pattern was noted with Molt-4, a non-Burkitt's lymphoma cell line. Using radiometric and microspectrofluorometric techniques, the expression of Fc-receptors, as detected by their capacity to fix aggregated IgG, paralleled the expression of serologically detectable Fc-receptors and Ia determinants. In contrast to beta 2-microglobulin, both Fc-receptor and Ia antigen expression increased following Hsv infection: this suggests a specific induction of these markers on human lymphoid cells following HSV infection. To our knowledge, this is the first report showing a specific induction of both Fc-receptors and Ia antigens by HSV following in vitro infection of human lymphoid cells.

Antigens, Surface↗
PubMed1978

Immune complexes in psoriasis with and without arthritis.

Two different assays were employed to detect soluble immune complexes in the serum of a large group of patients with psoriasis and psoriatic arthritis. Using a Raji cell assay no evidence of complexes was found. However, with the Clq deviation method, sera from 29% of the patients with psoriasis alone and 35% of those with associated arthritis, exhibited Clq reacting material.

Antigen-Antibody Complex↗
PubMed1977

Staphylococcal protein A in immunoferritin techniques.

Protein A (pA) of Staphylococcus aureus, by virtue of its reactivity with the Fc portion of a variety of mammalian immumoglobulins (IgG), can be used for electron-microscopical immunoferritin techniques. The conjugation of pA with ferritin (pA-F) by means of bis(4-fluoro-3-nitrophenyl) sulfone results in a highly specific marker for IgG in indirect labeling experiments. Native pA can be used as a noncovalent bridging agent between specific antibodies and antiferritin capturing the marker molecule. The use of pA and pA-F is demonstrated with a model system involving human erythrocytes and two rabbit antisera directed against different surface antigens of the human erythrocyte membrane.

Antibodies, Bacterial↗
PubMed1977

Quantitation of beta2-microglobulin and HLA on the surface of human cells. I. T and B lymphocytes and lymphoblasts.

Relative amounts of beta2-microglobulin (beta2m) and of HLA specificities were analysed on the surface of resting unfractionated peripheral human lymphocytes, enriched B and T cells, and on in-vivo- and in-vitro-stimulated lymphoblasts. Single-cell cytofluorometry and a very sensitive radioimmunoassay were used to determine as closely as possible the absolute amounts of membrane-bound beta2m/HLA antigens. B and T "resting" and "stimulated" lymphoid cells express very similar numbers of beta2m and HLA antigenic determinants, respectively, per unit of surface area when compared with each group, although beta2m was found to exist in two- to three-fold excess of HLA.

Antibodies, Anti-Idiotypic↗
PubMed1977

Quantitation of beta2-microglobulin and HLA on the surface of human cells. II. In vitro cell lines and their hybrids.

Beta2-microglobulin (beta2m) participates as an integral part in molecules of the major histocompatibility complex (MHC) type. Absence of beta2m makes the residual heavy MHC chain largely inactive as antigen. Striking reductions in the density per unit surface area of beta2m in seven out of nine malignant lymphoid tumour lines in comparison with normal lymphocytes or "immortalized" Epstein-Barr-virus-transformed lymphoblastoid lines were found is this study. This would seemingly represent a specific reduction in the ability of the malignant cells to express actively produced beta2m, since their HLA antigenic determinants were not reduced to the same extent and no indications were obtained suggesting that free beta2m could transfer from one cell to another. However, that beta2m is important in conveying serological specificities of MHC type to cells was shown by fusion of beta2m-negative and beta2m-positive cells, yielding hybrid cells with synergistically increased numbers of detectable, HLA-related determinants. Whether the reduction of beta2m on malignant versus nonmalignant lymphoid cells bears any relevance as to emergence of the malignant clones and resistance to possible anti-tumour reactions would now be an issue for study.

B-Lymphocytes↗
PubMed1976

Tumor-bound immunoglobulins. I. Further analysis of the characteristics of binding of immunoglobulins to in vivo-grown tumor cells.

Immunoglobulin (Ig) "coating" on different in vivo growing mouse tumors was investigated using several approaches. Radioiodine-labelled purified protein A from Staphylococcus aureus, a specific reagent for Fc of IgG, and/or iodinated purified antibodies against mouse immunoglobulins, were fixed by various in vivo-grown mouse tumor cells, but not by the corresponding in vitro-cultivated tumor cells. Removal of host macrophages from the in vivo tumor-cell preparations did not affect the fixation of anti-mouse Ig reagents by the tumor cells. After an initial lag period in vivo, the intensity of the Ig coating of tumor cells increased with time after tumor inoculation. Conversely, the detectable coating decreased rapidly as a function of time after ascites tumor cells were explanted in vitro at 37 degrees C. Iodoacetamide did partially block this 37 degree C in vitro-induced "uncoating process". Surface-bound Ig could also be released from in vivo-coated tumor cells treated at low pH in vitro. Analysis of the behavior of tumor-bound Ig indicated a composite pattern. At the membrane level, uncoating was best shown with in vitro incubation favorable to cellular metabolism; however IgG was detected equally well in the supernatants of the cells, whether they were incubated at 37 degrees C or at 4 degrees C, and so far has failed to display antibody activity towards uncoated tumor cells. This was in contrast to the case of IgG released from ascites tumor cells cultured at low pH in vitro: such eluted Ig, when neutralized, could rebind to the "same" uncoated tumor cells. Under favorable metabolic conditions, the fate of tumor-bound Ig might be one of internalization and/or of degradation.

Animals↗
PubMed1976

Analysis of cell-surface markers with staphylococcal protein A: fluorescence studies on mammalian lymphoid determinants.

Membrane antigens including different classes of immunoglobulins, transplantation antigens, beta2-microglobulin, T lymphocyte specific antigens, and virally determined surface components were investigated using fluorescein-labeled Staphylococcal protein A in combination with cytofluorometric studies. Lymphocytes of seven species: mouse, rat, guinea pig, pig, cow, monkey, and human, and of ten human lymphoma-derived lines were tested. Analysis of the differential expression of surface markers revealed a reproducible reaction of protein A with cell-surface Fc of IgG actively produced by lymphoid cells from human, monkey, guinea pig, and pig, and with passively attached IgG molecules in the form of antibodies, directed against cell surface antigens of all lymphoid cells tested. No surface Ig was detected on so-called T lymphocytes. The distribution of cell-bound Ig density among surface Ig-positive cells was found to be different depending upon the origin of the cells with regard to lymphoid organ; it was parallel among the lymphoma lines tested and on peripheral blood cells from human, monkey, and pig, although large variations in fluorescence intensity among individual cells and among the different lines were recorded. Beta2-microglobulin determinants were found equally well on enriched human T and B cells. Transplantation, and T lymphocyte-specific antigens were detected on the majority of the lymphoid cells and on a restricted population respectively.

Animals↗
PubMed1976

Tumor-bound immunoglobulins: an in vivo phenomenon of masked specificity.

We examined the specificity of the lg "coating" on murine tumor cells grown in vivo. Cells were treated in vitro for release of cell-bound lg from ascites tumors. Such uncoated cells showed an increased expression of tumor-associated antigens and a parallel decrease in intensity of the lg coat, but displayed no changes in the expressions of other normal membrane antigens. This was shown by a complement-dependent cytotoxicity assay and radioimmunoassay. These changes were attenuated if the tumor originated from animals that had been irradiated before tumor inoculation. No alterations were found with corresponding cells propaged in vitro and submitted to the same treatments. Our findings and others suggest tumor-specific antibodies among the lg coats detected on tumor cells grown in vivo.

Animals↗
PubMed1976

Epstein-Barr virus interactions with human lymphocyte subpopulations: virus adsorption, kinetics of expression of Epstein-Barr virus-associated nuclear antigen, and lymphocyte transformation.

In order to further understand Epstein-Barr virus (EBV)-lymphocyte interactions, we investigated a chain of events including: (i) EBV binding to human lymphocyte subpopulations; (ii) the earliest appearance of EBV-determined nuclear antigen (EBNA) in the lymphocytes after EBV infection; and (iii) establishment of continuous lymphoblastoid cell lines (LCL) by infecting with EBV different types of lymphocyte preparations from the same as well as from different donors. By using direct membrane immunofluorescence assay, we found that only a small fraction of human peripheral blood and cord blood lymphocytes (CBL), and possibly less than 31% of the T cell-depleted lymphocyte population, carry receptors for P3HR-1 strain of EBV. The number of cells carrying receptors for EBV did not vary considerably among different blood lymphocyte populations from several normal donors. EBV adsorption on lymphocyte subpopulations showed that purified thymus-dependent (T) cells and thymocytes did not adsorb EBV, in contrast to T cell-depleted lymphocyte populations and lymphoid cells from fetal liver and spleen. In CBL infected with EBV strain B95-8, EBNA was detected by anti-complement immunofluorescence as early as 18 h after infection. This indicates that EBNA is the earliest detectable EBV-determined intracellular antigen to appear after infection and before or during lymphocyte transformation by EBV. Transformation was observed only in lymphocyte cultures containing detectable thymus-independent B cells but not in cultures of purified T cells. With one exception (es-b-1), all the EBV-transformed LCL from different origins carried surface-bound immunoglobulins (a B cell marker). These included also the 10 LCL obtained by infecting cultures of adherent cells from different donors. With regard to its surface markers, ES-B-1 appeared to be an exceptional EBV genome-carrying line, and it also lacked the ability to form spontaneous rosettes with sheep erythrocytes (a T cell marker). Therefore, it is possible that ES-B-1 was derived from an atypical B cell or B cell precursor or from a so-called "null cell" transformed by EBV.

Adsorption↗
PubMed1975

A radioimmunoassay of cellular surface antigens on living cells using iodinated soluble protein A from Staphylococcus aureus.

Soluble protein A from Staphylococcus aureus does carry great promise as a marker for cellular surface determinants, due to its specific reaction with, and high affinity for, most subclasses of mammalian IgG. In this article we present the different parameters involved in a radioimmunoassay using 125-I-labelled protein A. Using such an approach the actual technical procedures involved are reported in detail together with tests for mammalian alloantigens, including HL-A in the human, H-2 in the mouse and AgB antigenic sites in the rat, as this presents an unique opportunity to compare them with already widely used assays for transplantation antigens. The different parameters of the assay are analysed in view of measuring with precision quantities of cell-surface IgG molecules, thereby allowing possible determinations of antigenic site numbers in a new and simplified manner.

Animals↗
PubMedDate not supplied

Rosette formation by human lymphoid cells with monkey red blood cells.

The present paper describes a study on rosette formation by human lymphoid cells with monkey erythrocytes (MRBC) obtained from two species: African green monkey (Cercopithecus aethiops) and rhesus monkey (Macaca mulata). All the lymphocyte preparations obtained from peripheral blood, tonsils, thymocytes, bone-marrow and spleen biopsies formed rosettes in variable proportions with erythrocytes obtained from these two monkey species tested. Cells of established lymphoblastoid cell lines characterized as being of either B- or T-cell origin also formed rosettes with MRBC. Taken together, the data obtained suggest that the MRBC-rosette assay cannot be reliably used for identifying lymphocyte subpopulations presently known to us, thus largely contradicting the observations previously reported by others on the use of this assay. In addition, we found that the binding sites for MRBC on the above lymphoid cells are highly sensitive to trypsin treatment and can fully be regenerated within 14-15 h when these treated cells are cultured at 37 degrees.

Animals↗
PubMedDate not supplied

[Allergy has no age].

Even though allergic reactions to local anesthesia are rare and even more so among elderly people, the present case demonstrates that a medication can be tolerated for a significant period of time before causing an accident. This illustrative case details the true nature of complications observed following local anesthesia and suggests a way of approaching the same to arrive at a definitive diagnosis. This method consists of a rigorous analysis of the clinical manifestations and allergologic testing. Local anesthesia is indispensable for both the dentist and the patient and anyone with allergies is at risk at being allergic to general anesthesia as well.

Aged↗