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V Daniel

Publications and source records attributed to V Daniel.

At least 37 records · Page 2Linked to original sources
PubMed1995

Role of quinone-mediated generation of hydroxyl radicals in the induction of glutathione S-transferase gene expression.

Induction of glutathione S-transferase (GST) Ya gene expression by a variety of chemical agents is mediated by a regulatory element composed of two adjacent AP-1-like binding sites and activated by the Fos/Jun heterodimeric complex (AP-1). We have previously shown that the induction of GST Ya gene expression and of AP-1 binding activity is regulated by intracellular glutathione (GSH) levels. To study the role of reactive oxygen species in the induction of AP-1 activity and GST Ya gene expression and their effect on intracellular GSH levels, we have exposed hepatoma cells to adriamycin and two synthetic quinones, Qcb and Qn, with different capacities to generate oxygen radicals. The kinetics of quinone-mediated generation of hydroxyl radicals were monitored in intact cells by a spin trapping technique and EPR spectral measurements. We find that quinones which can chelate Fe(III) ions, adriamycin and Qcb, are more effective in hydroxyl radical production than the nonchelating quinone Qn. Furthermore, we show that the induction of AP-1 binding activity and GST Ya gene expression by these quinones correlates with their oxygen radical production, adriamycin and Qcb being stronger inducers that Qn. The present study indicates that the AP-1-mediated induction of GST Ya gene expression is part of the response to oxidative stress. A transient increase by 2.5-fold in the intracellular GSH level was observed 30 min after exposure of cells to quinone and was followed by a rapid depletion of GSH. This increase in the GSH level represents an induction of GSH synthesis since it was blocked by buthionine sulfoximine, an inhibitor of gamma-glutamylcysteine synthetase.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

In vitro cytokine treatment of B cell defects in HIV-infected hemophilia patients.

HIV-infected patients exhibit defects in B cell differentiation and in the IL-6 response of B cells, in association with autoantibody formation against T cells. These autoantibodies have been implicated as important factors in the development of immunodeficiency disease. As the restoration of defective B cell responses might prevent autoantibody formation and the resulting immunosuppression, we studied whether in vitro treatment with recombinant IL-2 (rIL-2), recombinant IL-4 (rIL-4) or recombinant IL-6 (rIL-6) might restore the response of B cells of HIV-infected patients. B cells of 6 HIV-negative hemophilia patients, 4 HIV-positive patients at CDC stage II, III, 4 HIV-positive patients at CDC stage IV, and 6 healthy controls were tested in Staphylococcus aureus Cowan I (SAC-I)-stimulated B cell cultures and Pokeweed mitogen (PWM)-stimulated allogeneic B and T cell cocultures. B cell differentiation was assessed in a reverse hemolytic plaque assay and by ELISA determination of IgM, IgG and IL-6 in culture supernatants. In vitro application of rIL-6 resulted in suppression of both elevated unstimulated and mitogen-stimulated B cell responses in a dose-dependent manner which was in part due to feedback inhibition. PWM- and SAC-I-stimulated IgG and IgM responses, respectively, could be restored after addition of 10 U/ml rIL-2 in HIV-negative patients, but not in HIV-positive patients. Addition of rIL-4 to cultures resulted in suppression of both unstimulated and mitogen-stimulated IL-6 secretion and B cell responses. Severely depressed B cell responses in CDC IV patients were not significantly affected by cytokine application. These results indicate that defective Ig responses in HIV-negative patients may be restored by rIL-2 treatment whereas HIV-induced B cell defects are not corrected by supply of T cell help or cytokines promoting B cell growth and differentiation.

Autoantibodies↗
PubMed1995

[Cellular immune defect caused by postoperative irradiation in patients with squamous epithelial carcinomas of the upper aerodigestive tract].

The effect of locoregional postoperative radiation therapy on cellular immunity was investigated in 11 patients with head and neck cancer. During the course of the radiation therapy, total lymphocyte counts, CD8+ lymphocyte counts and especially CD4+ lymphocyte counts decreased significantly. The mean CD4+ lymphocyte counts dropped from 739/microliters to 183/microliters (p < 0.001) and the average CD4+/CD8+ ratio also decreased significantly. In addition all patients showed impaired in vitro lymphocyte stimulation responses to several mitogens, with reductions found to be 10% to 50% of normal responses. Within 3-4 weeks after radiation therapy there was a slight increase of CD4+ lymphocyte counts and the in vitro lymphocyte stimulation responses showed a tendency to normalization. These results indicate that locoregional postoperative radiation therapy in patients with head and neck cancer can induce a severe impairment of cellular immunity.

CD4 Lymphocyte Count↗
PubMed1994

Complement activation by recombinant HIV-1 glycoprotein gp120.

The mechanism of CD4+ cell depletion in HIV-infected patients is poorly understood. In this study we investigated whether rgp120 can activate the complement system in the absence of anti-gp120 Abs. We found that the complement proteins C4, C3d, C5b-9, and properdin bind to rgp 120-coated CD4+ T cells of healthy individuals when incubated in autologous serum. Activation of the complement system occurred primarily via the classical pathway and was abolished in sera deficient in C1q and C4 as well as in the presence of EDTA. No cell lysis was observed in a lymphocytotoxicity assay using human serum, possibly because of homologous restriction of complement lysis. In contrast, addition of rabbit sera induced lysis of the rgp 120-precoated cells. Cell lysis by rabbit serum was found to be because of naturally occurring IgM anti-gp 120 Abs. The rgp 120, which was immobilized on the surface of microtiter plates activated complement in the absence of lymphocytes. Complement activation by cell-bound HIV-1 envelope glycoprotein gp120 with subsequent opsonization may be relevant for the elimination of noninfected CD4+ T cells in HIV-infected patients.

Amino Acid Sequence↗
PubMed1994

Cooperative interaction between Ets and AP-1 transcription factors regulates induction of glutathione S-transferase Ya gene expression.

Induction of mouse glutathione S-transferase (GST) Ya gene expression by a variety of chemical agents is mediated by a regulatory element, EpRE, composed of an Ets and two adjacent AP-1-like binding sites. In this report we present evidence that the basal and inducible activity of EpRE is mediated by AP-1 transcription factor and that the cooperative interaction between AP-1 and an Ets protein contributes to enhance the EpRE inducibility. We also show that EpRE, similar to a single AP-1 site, when ligated to GST Ya gene promoter, is transactivated by c-Fos/c-Jun or c-Fos/Jun-B heterodimer and that c-Jun/c-Jun homodimer is an activator of an AP-1 site only in the context of collagenase gene promoter.

Animals↗
PubMed1994

Production of IL-10 by melanoma cells: examination of its role in immunosuppression mediated by melanoma.

Previous studies have shown that IL-10 may modulate immune responses towards the humoral arm by inhibiting production of cytokines involved in cell-mediated responses. In the present studies, we found that mRNA to IL-10 could be demonstrated in 66% of melanoma cell lines by PCR amplification of reverse-transcribed mRNA and in supernatants of the cell lines by ELISA. Release into the supernatants increased approximately 2-fold each day up to 3 days. The MW of 35S-labelled IL-10 secreted by melanoma cells was similar to that reported in previous studies. In the present studies we also examined whether IL-10 may be responsible for some of the immunosuppressive effects of the melanoma cell supernatants observed in previous studies, by testing whether MAbs against IL-10 could reverse the inhibitory effects of these supernatants. Recombinant IL-10 and melanoma supernatants were found to inhibit production of TNF-alpha, IFN-gamma, IL-2 and mixed lymphocyte reactions but reversal of these effects of melanoma supernatants by MAbs against IL-10 was only seen in the case of TNF-alpha production. These results extend the range of cell types known to produce IL-10 and indicate that malignancy of certain cell types may lead to unregulated production of IL-10 that could have the potential to modulate immune responses against the tumor.

Base Sequence↗
PubMed1994

Intracellular glutathione levels regulate Fos/Jun induction and activation of glutathione S-transferase gene expression.

Induction of glutathione S-transferase Ya and NAD(P)H:quinone reductase gene expression by a variety of chemical agents is mediated by regulatory elements, EpRE and ARE, composed of two adjacent AP-1-like binding sites and activated by Fos/Jun heterodimeric complex (AP-1). Recent studies show that chemical induction of glutathione S transferase Ya and quinone reductase gene expression is associated with an induction of c-fos and c-jun gene expression and AP-1 binding activity. In this report we present evidence that the AP-1 binding activity and the expression of chloramphenicol acetyltransferase activity from an EpRE Ya-cat gene construct are induced by an increase in intracellular oxidant levels. We observe that lowering the glutathione levels with buthionine sulfoximine, an inhibitor of gamma-glutamylcysteine synthetase, or diamide, a thiol-oxidizing agent, stimulates both basal and chemical-inducible expression of chloramphenicol acetyltransferase activity from EpRE Ya-cat and the AP-1 binding activity. Furthermore, we observe that the induction of these activities by a variety of chemical agents is inhibited by thiol compounds N-acetylcysteine and glutathione. These findings suggest that diverse chemicals that induce the AP-1 complex, leading to the AP-1-mediated transcriptional activation of glutathione S-transferase Ya gene expression, may act through a common mechanism involving the production of reactive oxygen species and depletion of reduced glutathione.

Buthionine Sulfoximine↗
PubMed1994

Fate and biocompatibility of three types of microspheres implanted into the brain.

The implantation of polymer devices in the brain that release neuroactive drugs locally and in a controlled manner is gaining increasing interest. The fates and tissue reactions of poly(epsilon-caprolactone), ethylcellulose, and polystyrene microspheres, prepared by the solvent evaporation method, radiosterilized by gamma-irradiation, and stereotactically implanted in rat brain have been studied by routine staining and immunohistochemistry. During the first few days after implantation, a nonspecific astrocytic brain tissue reaction was observed along with a macrophagous-microglial cell reaction typically found following any damage in the central nervous system, except in the presence of certain foreign body giant cells. Nine months into the experiment, microspheres appeared to be engulfed by histiocytic cells. The microsphere cluster was surrounded by a sheath composed of collagen and astrocytic cells. No necrosis was observed, suggesting the absence of toxicity. In some animals, however, an hydrocephalus developed as a result of obstruction of the medial ventricle by some microspheres.

Animals↗
PubMed1994

Comparative study of antibodies that are associated with disease progression in HIV disease.

Two types of antibodies which previously were found to be inversely associated with CD4+ cell counts and which may contribute to the progression of HIV disease were measured in parallel in 55 serum samples of 7 longitudinally tested HIV-infected patients (4 homosexual men, 3 haemophilic men) and in 15 serum samples from 15 patients with advanced AIDS. HIV-infection enhancing antibodies were determined in the presence of near-physiologic human complement concentration using a complement receptor type 2 (CR2) carrying HIV-target cell line. IgG and IgA class autoantibodies directed against human IgG-Fab fragments were measured in specific ELISA assays. In agreement with our previous studies obtained in HIV-seropositive haemophilic patients, significant negative correlations were found between CD4+ cell counts and IgG anti-Fab and IgA anti-Fab antibodies (Spearman correlation coefficient r = -0.587, P < 0.0001; and r = -0.269, P = 0.024, respectively). A significant positive correlation was observed between complement-dependent enhancing antibodies and IgA anti-Fab antibodies (r = 0.408, P = 0.003), whereas the correlation with IgG anti-Fab antibodies was only weak (r = 0.288, P = 0.034). Serum samples with high titres of complement-dependent enhancing antibodies had almost 3 times higher IgA anti-Fab autoantibody activity than sera with low titres (P = 0.0038). Our findings indicate that the two disease markers in HIV disease, enhancing antibodies and autoantibodies directed against the Fab moiety of IgG, are not identical. However, anti-Fab antibodies may contribute to complement-dependent HIV infection enhancement.

Acquired Immunodeficiency Syndrome↗
PubMed1994

IL-6 independent monocyte/B cell defect in renal transplant recipients with long-term stable graft function.

We showed previously that the B cell response in renal transplant recipients with long-term stable graft function (ST patients) is significantly affected by T suppressor activity. To further assess the role of the monocyte/B cell compartment in B cell regulation, we tested B cell responses in 30 ST patients (> 1 year after transplant) and 15 patients with chronic rejection (CR patients). PWM was used for T cell-dependent B cell stimulation in an allogeneic coculture system, and SAC I for T cell- and monocyte-independent B cell stimulation. B cell responses were assessed in a reverse hemolytic plaque assay and by ELISA determination of IgM, IgG, and IL-6 in culture supernatants. In PWM-stimulated cultures of ST patients, we found a diminished immunoglobulin-secreting cell (ISC) formation (P < 0.0001 and P < 0.05, compared with controls and CR patients, respectively) and diminished IgM secretion (P = 0.06 and P < 0.01, respectively), whereas CR patients and controls were not significantly different. Two of 35 (6%) controls and 3 of 15 (20%) CR patients, in contrast to 20 of 30 (67%) ST patients, displayed defective ISC formation (P < 0.0001). This defective B cell response may be the result of reduced CD36+ monocyte counts in ST patients (P < 0.005), as PWM-stimulated B cell responses and CD36+ cell counts were significantly associated (P < 0.05, ISC and IgM response). A role of monocytes in the impairment of B cell function is further supported by decreased plasma neopterin levels in ST compared with CR patients (P = 0.0001), a significant association between plasma neopterin and PWM-stimulated B cell responses (P < 0.05, ISC response; P = 0.0001, IgM response), and by the finding that B cell responses in ST patients after monocyte-independent stimulation with SAC I were unaffected. ST and CR patients showed no significant differences in B cell subsets, plasma IL-6, or IL-6 responses of mitogen-stimulated cultures. Our data indicate that an IL-6-independent monocyte or B cell defect plays a role in the maintenance of stable transplant function.

Adult↗
PubMed1994

Isotypes and IgG subclasses of anti-Fab antibodies in human immunodeficiency virus-infected hemophilia patients.

We reported recently that anti-Fab autoantibodies of the IgG isotype are associated with the decrease of helper/inducer (CD4+) lymphocytes in human immunodeficiency virus-infected (HIV+) hemophilia patients with acquired immunodeficiency syndrome (AIDS) or AIDS-related complex (ARC). In the present study we investigated the subclass distribution of IgG-anti-Fab autoantibodies, and whether anti-Fab antibodies of the IgA and IgM isotypes also are associated with the development of AIDS. Sera of HIV+ patients with AIDS had significantly higher IgA-anti-Fab activity than HIV+ patients with ARC (p < 0.02), HIV+ patients without AIDS/ARC (p < 0.0001), HIV-negative (HIV-) patients (p < 0.001), or healthy controls (p < 0.0001). An inverse association was found between IgA-anti-Fab activity and CD4+ cell counts (r = -0.396, p < 10(-6)). In contrast, no association of CD4+ cell counts was observed with IgM-anti-Fab. However, IgM-anti-Fab was significantly increased in patients with thrombocytopenia. We found a significant association between IgA-anti-Fab activity and serum neopterin concentrations (r = 0.310, p < 10(-5)). IgG-anti-Fab activity was detected mainly in the IgG3 fraction, although in HIV+ patients with AIDS/ARC various IgG subclasses were present. Affinity-purified anti-Fab antibodies isolated from sera of AIDS patients bound to rgp120-preincubated CD4+ cells of a healthy individual, supporting our hypothesis that anti-Fab antibodies and free circulating gp120 molecules are involved in the elimination of uninfected CD4+ cells. Removal of anti-Fab autoantibodies from the circulation by immune adsorbance might be a useful approach in the treatment of AIDS.

AIDS-Related Complex↗
PubMed1994

Induction of AP-1 (Fos/Jun) by chemical agents mediates activation of glutathione S-transferase and quinone reductase gene expression.

A regulatory element, EpRE, was found to be responsible for the induction of mouse glutathione S-transferase (GST) Ya gene expression by a variety of chemical agents such as planar aromatic hydrocarbons, diphenols, phorbol ester, phenobarbital and electrophilic compounds. The EpRE is composed of two adjacent AP-1-like binding sites and was recently found to be activated by Fos/Jun heterodimeric complex (AP-1). In this report we show that regulatory elements ARE, previously demonstrated to mediate the chemical induction of rat GST Ya and quinone reductase genes, have a similar structure with EpRE and are activated by Fos/Jun complex. The activation of GST Ya and quinone reductase genes by a variety of chemical inducers is found to be associated with an increase in AP-1 binding activity. We present evidence that chemical agents induce expression of c-fos and c-jun proto-oncogenes and an enhanced synthesis of protein components of AP-1 complex. We suggest that the increased synthesis of AP-1 complex followed by an AP-1-mediated transcriptional activation of GST Ya and quinone reductase genes may provide a molecular mechanism for the induction of these drug-metabolizing enzymes by chemical agents.

Arsenates↗
PubMed1993

A new method for determining anti-B cell antibodies and their specificity using flow cytometry.

We describe a new flow cytometric B cell crossmatch method with improved sensitivity and specificity. It is based on the coating of B cell surface immunoglobulins with an unconjugated polyvalent anti-human immunoglobulin antibody. The method also provides a means for determining the specificity of anti-B cell antibodies and, potentially, for anti-HLA class II antibody specificity differentiation (DR, DQ or DP) in a binding inhibition test using mouse monoclonal antibodies directed against human HLA class II antigens.

Antibody Specificity↗
PubMed1993

Sequence analysis suggests a recent duplication of the growth hormone-encoding gene in Tilapia nilotica.

The sequence of two growth hormone(GH)-encoding genes from tilapia fish (Tilapia nilotica) is reported. Our data indicate that the presence of two GH in the tilapia genome is a consequence of a relatively recent duplication event. The two genes are highly homologous, having a similar intron (five)/exon (six) arrangement, and both encode an identical polypeptide. Sequence similarity extends up to bp -628 upstream to the transcription start point, after which the sequences of the two genes are not related to each other. The presence of two GH in the tilapia genome is supported both by the nucleotide sequence and by genomic DNA blot hybridization analysis. Tilapias, like salmonids, contain an extra intron compared with the mammalian GH structure. We suggest that within the superorder Teleostei, the insertion of intron 5 into GH took place after the evolutionary separation of Cyprinoidea, but before Isospondyli (salmonids) and Acanthopterygii (tilapias) were separated. Thus, the additional intron which is probably present in many teleost fish GH may provide an excellent natural marker for evolution and classification studies.

Amino Acid Sequence↗
PubMed1993

Phenobarbital induction of AP-1 binding activity mediates activation of glutathione S-transferase and quinone reductase gene expression.

Phenobarbital is an inducer of xenobiotic-metabolizing enzymes, such as cytochrome P-450, glutathione S-transferases (GSTs) and NAD(P)H:quinone reductase, as well as being a promoter of hepatocarcinogenesis. The molecular mechanisms regulating these biological activities are, however, unknown. In this paper we show that induction by phenobarbital of GST Ya and quinone reductase gene expression is mediated by regulatory elements, EpRE and ARE respectively, which are composed of two adjacent AP-1-like binding sites. EpRE was recently found to be activated by a Fos/Jun heterodimeric complex (AP-1). Here we show that phenobarbital induces an increase in AP-1 binding activity in nuclear extracts of cultured hepatoma cells. Furthermore, we observe that the induction of chloramphenicol acetyltransferase (CAT) activity from an EpRE Ya-cat gene construct and of AP-1 binding activity by phenobarbital is inhibited by the thiol compounds N-acetyl-L-cysteine and glutathione. These results suggest that the phenobarbital induction of AP-1 activity, leading to the AP-1-mediated transcriptional activation of the GST Ya and quinone reductase genes, may involve production of reactive oxygen species and an increase in intracellular oxidant levels, which is prevented by thiol compounds. In view of the involvement of AP-1 in the control of cell proliferation and transformation, the induction by phenobarbital of AP-1 binding activity observed here provides a possible molecular mechanism for the tumour-promoting activity of this drug.

Acetylcysteine↗