Search PubMed⌕ Search

Biomedical subjects

C Fernandez

Publications and source records attributed to C Fernandez.

At least 181 records · Page 10Linked to original sources
PubMed1984

Role of antigen in the regulation of the immune response to dextran B512.

Dextranase mixed with dextran in vitro or injected into mice before the antigen abolished the immunogenicity of both thymus-dependent and thymus-independent forms of dextran. Dextranase could degrade dextran in vivo even when given 6-15 days after the antigen. Dextranase injected after the antigen suppressed the immune response when given 24 h, but not 48 h, after the antigen, indicating that the antigen must interact with the immune system for 48 h to initiate a response. Thereafter , the B cells are independent of further antigen stimulation. The induction of autoanti -idiotypic anti-dextran antibodies was abolished if dextranase was given 24 h, but not 48 h, after the antigen, indicating that anti-idiotypic antibodies can be induced in the absence of antigen or immune complexes once anti-dextran antibodies have been synthesized.

Antibody Formation↗
PubMed1984

[Chronicity, chronicization, systematization of delusions].

Chronicity in psychopathology is indicative of a term, a decay. Chronicization only leads the way to this term. Here, chronicization is taken literally as an inscription in the time course of delusions. The mechanism of systematization seems to be a central mark in the approach to chronic delusions. It is not an alienation or an irreversible closing but an attempted accommodation with reality in the life of psychotic subjects, irrespective of the delusional structure. The role of therapy and drug treatment as a follow-up may in that case assume another meaning.

Antipsychotic Agents↗
PubMed1984

Gonococcal perihepatitis: diagnostic and therapeutic value of laparoscopy.

Two patients with pelvic and right hypochondrial pain and with purulent vaginal exudate in which Neisseria gonorrhoeae was isolated, are presented. Laparoscopy was used in both cases. A diagnosis of perihepatitis was made by demonstrating the typical adhesions in "violin string" shape and by obtaining clinical improvement after breaking up those adhesions. Our conclusion is that laparoscopy is a useful diagnostic and therapeutic procedure in young women with pain in the right upper quadrant of the abdomen and with signs of lower genital infection.

Adult↗
PubMed1983

Mechanism of unresponsiveness to the alpha 1-6 epitope of dextran B512 in a C57BL substrain.

C57BL/10ScCr mice are low responders to the alpha 1-6 epitope of dextran B512, although other C57BL mice are high responders. Both thymus-independent and thymus-dependent forms of dextran failed to induce an immune response in C57BL/10ScCr mice, but dextran functioned as a good carrier for antihapten responses in this strain. Dextran is a potent polyclonal B cell activator for cells from C57BL/10ScCr mice, although such cells are not activated by LPS. The C57BL/10ScCr mice possess the Igh-V gene coding for antibodies against dextran and the antidextran antibodies induced in (A X C57BL/10ScCr)F1 hybrids share an idiotype with antidextran antibodies produced in C57BL/10 mice. Bone marrow cells from C57BL/10ScCr mice do not respond to dextran when transferred into lethally irradiated C57BL/10 mice and C57BL/10 cells transferred into C57BL/10ScCr mice give a strong antidextran response. Thus, B cells having both the Igh-V gene coding for antibodies against dextran and activation receptors for dextran cannot be activated into antibody synthesis against any form of this immunogen. This determinant specific immunodeficiency suggests the existence of as yet unknown regulatory influences on Igh-V gene expression or B cell activation.

Animals↗
PubMed1983

Genetic analysis of the low responsiveness to dextran B512 in CBA/N and C57BL/10ScCr mice.

CBA/N and C57BL/10ScCr mice are low responders to the antigen dextran B512. This is due to the Xid gene in CBA/N mice and to unknown genes in C57BL/10ScCr mice, although this strain is unresponsive to lipopolysaccharide (LPS) due to a defective gene in the fourth chromosome. The female F1 hybrids (C57BL/10ScCr X CBA/N) and (CBA/N X C57BL/10ScCr) were low responders to dextran, although the Xid gene is not expressed in these hybrids, indicating lack of genetic complementation. In contrast, female F1 hybrids between the dextran high-responder strains CBA or C57BL/10 as one parental strain and the low-responder strains CBA/N or C57BL/10ScCr as the other parental strain, respectively, were responders to dextran. The C57BL/10ScCr mice did not appear to have an X-linked gene determining low responsiveness to dextran. The findings suggest that the only defect in CBA/N mice cannot be the Xid gene and the only defect in C57BL/10ScCr mice cannot be the gene determining unresponsiveness to LPS.

Animals↗
PubMed1983

The polyclonal lipopolysaccharide response is accessory-cell-dependent.

Different concentrations of spleen cells from C57BL.10 mice were activated with lipopolysaccharide (LPS), and DNA synthesis and IgM and IgG secretion were measured. The dilution curve was sigmoid, and the response was rapidly lost below a certain cell concentration. In the presence of thymocytes or spleen cells from the LPS-non-responder strain C57BL.10/ScCr the dilution curve for the LPS response of cells from C57BL.10 mice became linear, and the overall response was increased. Irradiated cells could not restore the response at suboptimal cell concentrations. In addition, enriched T cells restored the response as well as normal spleen cells, whereas enriched B cells did not. We compared the restoring capacity of different filler cells for the LPS response with that of a plasmacytoma cell line cultured at suboptimal cell concentrations. The results are compatible with the idea that the filler cells provide growth-stimulating activity to LPS-responsive cells but growth-supporting activity to the tumour cells. Furthermore, highly enriched B-cell populations respond poorly to LPS, but the response can be partly restored by filler cells. These data suggest that the LPS response is accessory-cell-dependent.

Animals↗
PubMed1983

Direct determination of inorganic phosphorus in serum with a single reagent.

Estimation of inorganic phosphate in serum based on the formation of "molybdenum blue" may be simplified by eliminating the reduction stage. The yellow complex formed by the reaction of phosphate with molybdate in an acid medium is measured at 390 nm. The yellow complex behaves in accordance with Beer's law over a wide concentration range (to at least 80 mg of P per liter in the initial sample); its molar absorptivity at 390 nm is 2.51 X 10(3) L mol-1 cm-1. Sensitivity is increased in the presence of a detergent (triethanolamine lauryl sulfate), which is also used to dissolve the proteins. Because only one reagent is used (a stable combination of, per liter, 20 mmol of sodium molybdate, 82 mmol of nitric acid, and 100 mg of the detergent), the method is simple and rapid. We describe a manual procedure and an automated one. Within-run precision was 1.9%, and day-to-day precision less than 7%. Results by the automated method compare favorably (r = 0.96) with those obtained by Drewes's method (Clin Chim Acta 39: 81-88, 1972).

Detergents↗
PubMed1982

Development and continuous growth in culture of interleukin 2-producer lymphocytes from athymic nu/nu mice.

Splenocytes of nu/nu mice treated with serum thymic factor (FTS) for 3 or more days followed by stimulation with either phorbol myristate acetate (PMA) or concanavalin A (Con A) produced interleukin 2 (IL 2) as determined in two indicator systems, namely, support of growth of IL 2-dependent T cells and promotion of Con A-initiated mitogenesis of thymocytes. However, neither mitogens nor FTS alone could induce nude mice cells to product IL 2. Supernatants derived from the tumor cell line WEHI-3 (WEHI-3 conditioned media) induced and supported continuous growth in culture of Thy-1.2+, Lyt-1+2- lymphocytes from athymic nude mice capable of producing IL 2 after their stimulation by either PMA or Con A. The growth of these IL 2-producer cell lines strickly depends on the presence of WEHI-3 conditioned media, as in the absence of it they die 24-48 h later. In addition, WEHI-3 conditioned media have been supporting the growth of IL 2-producer cell lines derived from nude mice for 3 1/2 months. The helper factor contained in WEHI-3 conditioned media responsible for the above biological activity has an apparent mol. wt. of approximately 40 000 as determined by Sephadex G-100 chromatography and lacks IL 1 and IL 2 activities, but efficiently supports the growth of IL 2-producer cells derived from nude mice and the peripheral blood of normal human volunteers. These results indicate that the helper factor in WEHI-3 conditioned media which enables the generation and continuous proliferation in culture of IL 2-producer cells in nude mice is distinct from interleukin 1, IL 2 and FTS (mol. wt. 864). Finally, the possibly functional relationship of FTS and the helper factor produced by WEHI-3 cells is discussed.

Animals↗
PubMed1982

Accessory function of human tumor cell lines. I. Production of interleukin 1 by the human histiocytic lymphoma cell line U-937.

The established human histiocytic lymphoma cell line U-937 spontaneously produced a factor with biological activity similar to that ascribed to interleukin 1 (IL 1). Actually, supernatants from U-937 cells promoted proliferation of thymocytes initiated by concanavalin A (Con A) and replaced the requirement of accessory cells for activation of highly purified circulating T lymphocytes induced by Con A. Phorbol myristate acetate (PMA) significantly increased the titers of the helper factor produced by U-937 cells as compared to that secreted by non-PMA-treated U-937 cells or PMA-stimulated P388D1 murine macrophage tumor cells. Generally U-937 cells did not secrete detectable IL 1 activity during the first 24-48 h of culture. However, after this initial period the level of IL 1 activity increased and reached a maximum at 5-6 days of culture. Finally, the helper factor released by U-937 cells had an apparent mol. wt. of 12000-15000 as determined by Sephadex G-100 chromatography and lacked interleukin 2 activity as shown by its inability to support growth of IL 2-addicted T cell lines. To our knowledge this is the first report of an established human cell line capable of producing IL 1.

Animals↗
PubMed1982

Studies on the selection of streptomycetes in the rhizoplane of sugar-cane.

The overwhelming majority of species of Streptomyces (S. aburaviensis, S. chromofuscus, S. collinus, S. tenebrarius, S. galilaeus, etc.) and Streptoverticillium aureoversales indigenous in the cultivated horizon of the red ferralitic tropical soil of an investigated sugar-cane plantation, were completely lacking in the root surface region of this plant. Only two species (S. griseorubiginosus and S. viridochromogenes) characterized by very broad C- and N-source utilization spectra, proved capable of colonizing the roots of sugar-cane under natural circumstances. They are not stable members of the rhizoplane but, in contrast to many other species of Streptomyces, are very successful occasional root colonizers. S. viridochromogenes occurred also in the root far soil region but S. griseorubiginosus could only be detected in the rhizoplane.

Ecology↗
PubMed1982

Cyclosporin A inhibits thymus-dependent but not thymus-independent immune responses induced by dextran B512.

We have compared previous studies of the immune response to dextran (Dx) B512 in thymus-deficient nu/nu and thymectomized, lethally irradiated, and bone marrow-reconstituted mice with those obtained with cyclosporin A (CyA) as a T-cell-inhibiting drug. Our data show that only immune responses to TD forms of Dx B512 are susceptible to suppression by CyA, whereas anti-alpha 1-6 and anti-DNP antibodies induced by high molecular weight dextran and DNP-native Dx, respectively, were not inhibited. Similar results were obtained when polyclonal responses were studied. The polyclonal response induced by another dextran preparation, the polyanion dextran sulphate (DxS), was inhibited by CyA to the same extent as polyclonal T-cell activation by T-cell mitogens.

Animals↗
PubMed1982

Ontogenic development of the suppressed secondary response to native dextran.

The ontogenic development of the plaque-forming cell (PFC) response to the thymus-independent (TI) antigen alpha 1-6 native dextran B512 was studied to determine when the first minimal amounts of anti-dextran antibodies are formed. Substantial antibody responses to certain other TI polysaccharide antigens arise during the first month of life, whereas the development of the response to native dextran has been found to be conspicuously delayed in high-responder mice. Results indicated that CBA mice began to produce minimal amounts of anti-dextran antibodies between 15 and 21 days of age, and the development continued progressively until peak levels were reached at 90 days of age. The alpha 1-6 native dextran system is also one of the few murine models in which endogenous anti-idiotypic antibodies are formed subsequent to anti-dextran production. It has been shown that the anti-idiotypic antibodies are responsible for specific inhibition of secondary PFC responses to dextran. Suppression of the secondary response was used here to ascertain whether the initial low level of anti-dextran antibodies elicited in 15-day-old animals was sufficient to lead to inhibition of the secondary response. The approach confirmed the initiation of anti-dextran production at 15-21 days of age and indicated that the small amount of anti-dextran antibodies produced at this age was sufficient to induce the mechanism leading to suppression of the secondary response.

Age Factors↗
PubMed1982

Potentiation of the PFC response to thymus-independent antigens by heterologous erythrocytes.

Immunization with horse erythrocytes (HRBC) and a thymus-independent (TI) antigen of the TI-2 category, such as a native dextran, dinitrophenyl-dextran (DNP-dextran), or DNP-Ficoll, resulted in a three- to four-fold enhancement of the plaque-forming cell response to the TI antigen. The effect was found to be T-cell associated, since cyclosporin A abrogated enhancement. The T cells of T-cell factor involved were elicited early in the response to HRBC and acted on the initial stages of the TI response. The HRBC-induced potentiation affected only B cells activated by the TI antigen; it could not induce a TI response when TI-2 antigen was given under nonresponsive conditions; and it had only a slight effect on the response to a thymus-dependent (TD) antigen. A soluble TD antigen, bovine serum albumin-coupled dextran (BSA-dextran), did not have potentiating ability equivalent to that of the particulate HRBC. It was concluded that non-specific T-cell help can influence TI-2 responses when they are present simultaneously.

Adjuvants, Immunologic↗