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Biomedical subjects

J F Bach

Publications and source records attributed to J F Bach.

At least 667 records · Page 37Linked to original sources
PubMed1976

[Immunosuppressive agents and infection (author's transl)].

Immunosuppressive agents often cause severe infection sometimes due to organisms rarely encountered in other circumstances. Virus and parasitic infections, together with tuberculosis and salmonella may be particularly frequent during treatments which depress. T lymphocytes. Gram positive bacterial infections are mainly caused by substances inducing cell B immune deficeincy. In the light of this data, verified both by animal experiments and clinical experience, it is important to determine the target cell of the main immunodepressive agents used in clinical medicine. Azathioprine and antilymphocyte serum act mainly on T lymphocytes whereas alkylating agent are at least as active on B lymphocytes as on T lymphocytes. The mode of action of corticosteroids is particularly obscure. T cells appear, on the whole, to be resistant to corticosteroids, whereas monocytes and macrophages are very sensitive.

Animals↗
PubMed1975

[Immunologic study of subacute infectious endocarditis through the search for circulating immune complexes. Preliminary results apropos of 13 cases].

The detection of circulating immune complexes by precipitation by polyethylene glycol represents a valuable technique of study in sub-acute bacterial endocarditis. In a series of 13 patients, this measurement was carried out, confirming the quasi-constant presence of circulating immune complexes in active S.B.E. This might be of diagnostic value in forms with negative blood culture and, further, make it possible, subsequently, to find the antigen responsible by dissociation of the circulating immune complexes.

Adult↗
PubMed1975

[A correlation between histocompatibility antigens HL-A 1 and 8 and an improved defense in the chronic uremic patient against hepatitis B virus].

Histocompatibility antigens have been studied in 328 uraemic patients treated by chronic haemodialysis, of whom 201 were contaminated by hepatitis-B virus associated antigen (HBs Ag). The frequency of the phenotypes HL-A 1 (36.2%), HL-A 8 (29.8%) and the HL-A 1,8 (23.4%) was significantly higher in the group of 47 patients who were able to eliminate HBs Ag after a transient antigenemia, than in the group of 154 patients who became chronic carriers of this antigen (P less than 0.01 for HL-A 1,8 association). These frequencies were also higher than the corresponding ones in the normal French population (P less than 0.01 for HL-A 8; P less than 0.001 for HL-A 1,8 association). In contrast, the HL-A frequencies observed in the group of patients with persistent antigenemia were not different from those observed in healthy controls. In conclusion, the presence of HL-A 1,8 phenotype seems to be correlated, in uraemic haemodialyzed patients, with a better immunological response against hepatitis B virus and hence, with the ability to elminate HBs Ag.

Antigens, Viral↗
PubMed1975

Regulation of theta-antigen expression by agents altering cyclic AMP level and by thymic factor.

Thymic factor, cyclic AMP, and products increasing its cellular level, such as Prostaglandin E1, induce the appearance of the theta-antigen on T-cell precursors whether assessed by a rossette-inhibition assay or a cytotoxic assay after cell fractionation on BSA discontinuous gradiet. Synergism has been demonstrated between cyclic AMPT and TF for that effect. Conversely, decrease of theta expression has been obtained by altering cyclic AMP level in theta-positive cells either increasing it by dibutyryl cAMP treatment or decreasing it by indomethacin treatment. Finally, these data suggest the involvement of cyclic AMP in the regulation of theta expression under thymic hormone control.

Acetylcholine↗
PubMed1975

Binding of autologous erythrocytes to immature T-cells.

A small percentage of normal mouse thymus and spleen lymphocytes form rosettes with autologous erythrocytes. The number of these autologous rosettes increases 15- to 20-fold after adult thymectomy and to a lesser degree with aging. Autologous rosette level is also abnormally high in nude (congenitally athymic) mice. The high level of autologous rosette-forming cells found after adult thymectomy is normalized by injecting ng amounts of purified circulating thymic factor. Autologous rosette-forming cells adhere to nylon, belong to the less dense spleen cells, are in majority steroid-resistant in the thymus. All these properties suggest that autologous rosette-forming cells might belong to immature T-cell (thymic-dependent cell) precursors.

Animals↗
PubMed1975

Evaluation of serum thymic hormone and of circulating T cells in rheumatoid arthritis and in systemic lupus erythematosus.

The presence of a serum factor secreted by the thymus has been demonstrated in the serum of mice and man using a rosette inhibition assay. This factor is a peptide with a molecular weight close to 1,000. Its level is age dependent, being stable until the age of 6 months in mice and until 20 years in man. New Zealand Black mice show a premature cessation of thymic hormone secretion preceeding the onset of other T cell abnormalities and auto-immunity. Before any treatment the serum thymic hormone level is abnormally low in most cases of SLE even in patients under 25, an age where control subjects still show high hormone levels. Conversely, normal or high levels are found in RA, PARTICularly in patients over 40 who showed in 60% of cases a hormone level significantly higher than normal controls of the same age. In keeping with this data T cells evaluated by SRBC spontaneous rosette formation show low figures in some patients with active SLE and normal or high values in most cases of RA.

Adolescent↗
PubMed1975

Characteristic immunohistochemical and ultrastructural glomerular lesions in Nude mice.

Kidney glomerular lesions were studied by light microscopy and immunofluorescence in 17 congenitally athymic Nude mice and 25 of their phenotypically normal littermates. The 3-month-old mice had glomerular deposits of total IgG, IgG2, IgM, and C3, but IgG1 was consistently absent and IgA was present in only 30 per cent of cases. Conversely, the 6-month-old littermates showed no deposits. However, the 9- and 12-month-old littermates had glomerular deposits of all of the immunoglobulins and C3. Kidney tissue from five Nude mice was studied by electron microscopy. In three of these five mice the mesangial and subendothelial deposits contained characteristic double layered lamellar structures approximately 130 A wide. Antinuclear antibodies were found in the serum of 3 or 10 Nude mice and 1 of 12 littermates. Different hypotheses on the origin of the characteristic lamellar structures are proposed. The significance of the early development of autoimmunity and glomerular lesions in Nude mice is discussed.

Animals↗
PubMed1975

Studies on B- and T-cell receptors for lysozyme.

BALB/c mice have been immunized by intravenous administration of native or reduced and alkylated lysozyme. Primary immune response to these antigens was studied at the humoral level (by the Farr assay) and at the cellular level (by the rosette and the plaque assays using lysozyme coupled to sheep or pigeon erythrocytes). Antibodies and theta-negative RFC were specific for the antigen used for immunization. Specific inhibition of theta-negative RFC after incubation with the soluble immunizing antigen confirmed this specificity. Conversely, most theta-positive RFC had double specificity both to native and denatured lysozyme and showed lower avidity for the immunizing antigen, as shown by inhibition studies with soluble antigen. These data suggest that T cells have a broader specificity for lysozyme than B cells and also that, in this particular system, cytophilic antibodies are probably not responsible for the formation of theta-positive rosettes.

Animals↗
PubMed1975

In vitro culture of functional human thymic epithelium.

Cultures of pure epithelial cells have been obtained from human thymus. Incubation of spleen cells from adult thymectomized mice on these cultures rendered RFC sensitive to inhibition by anti-theta serum, whereas no effect was obtained with fibroblasts or spleen cell cultures. The fact that theta conversion was obtained when spleen cells were incubated in the thymic culture placed within a Millipore chamber indicates that theta conversion was due to the effect of a humoral factor.

Animals↗