Search PubMed⌕ Search

Biomedical subjects

G Dorval

Publications and source records attributed to G Dorval.

29 records · Page 2Linked to original sources
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↗
PubMedDate not supplied

[Profile of aged traffic victims on the road to Sherbrooke (Quebec)].

This article draws a portrait of the victims, 65 years of age and over, of road accidents in a mid-size Quebec town. By examining four variables--age, sex, condition of the victims and the type of road users--we measured the magnitude and severity of road accident injuries in senior citizens, and identified those road users most at risk. Results indicate that, in the city of Sherbrooke as elsewhere in Quebec, road accident injuries are increasing slowly but constantly in this age group. Analysis of the severity of injuries and of the category of road users, shows that senior citizens have a high degree of vulnerability and are over-represented in statistics dealing with pedestrians who are victims of accidents. We discuss these results and their impact on public health.

Accidents, Traffic↗
PubMedDate not supplied

[Studies on tumour--associated immunoglobulins in human cancer].

Human sarcomas, carcinomas and brain tumours were assayed for the presence of immunoglobulins IgG. Among 16 tumours tested, 14 had detectable amount of IgG that could be released when incubated in culture conditions. Addition of iodoacetamide--a metabolic inhibitor--inhibited this " uncoating process ". The uncoated cells rebound IgG if incubated subsequently with any of the cancer sera tested. However, when the autologous serum was present during the uncoating incubation, subsequent rebinding at 4 degree C of IgG from the same or other cancer sera was significantly decreased compared to alquots pre-incubated in other sera.

Biopsy↗
PubMedDate not supplied

[Abnormal specificities of immune alloantisera].

Sera from repeatedly immunized with allogenic lymphocytes contain IgG that can be fixed by syngenic tumour cells. When compared to the specific anti-H-2 immune response, the paradoxical tumour reactivity is often very high, suggesting an active immunization process. Selective absorptions have demonstrated that the majority of these "anomalous" IgG are directed against membrane components of tumour cells. The nature of the detected tumour-associated determinants is not well elucidated: they are not found on normal embryonnic or adult tissue, but are highly expressed by all in vitro murine malignant cell lines thus far tested, and to a lesser extent by the corresponding in vitro maintained tumours.

Animals↗