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J Varga

Publications and source records attributed to J Varga.

At least 55 records · Page 3Linked to original sources
PubMed2000

Antagonistic regulation of type I collagen gene expression by interferon-gamma and transforming growth factor-beta. Integration at the level of p300/CBP transcriptional coactivators.

Among the extracellular signals that modulate the synthesis of collagen, transforming growth factor-beta (TGF-beta) and interferon-gamma (IFN-gamma) are preeminent. These two cytokines exert antagonistic effects on fibroblasts, and play important roles in the physiologic regulation of extracellular matrix turnover. We have shown previously that in normal skin fibroblasts, TGF-beta positively regulates alpha2(I) procollagen gene (COL1A2) promoter activity through the cellular Smad signal transduction pathway. In contrast, IFN-gamma activates Stat1alpha, down-regulates COL1A2 transcription, and abrogates its stimulation induced by TGF-beta. The level of integration of the two pathways mediating antagonistic collagen regulation is unknown. We now report that IFN-gamma abrogates TGF-beta-stimulated COL1A2 transcription in fibroblasts by inhibiting Smad activities. IFN-gamma appears to induce competition between activated Stat1alpha and Smad3 for interaction with limiting amounts of cellular p300/CBP. Overexpression of p300 restored COL1A2 stimulation by TGF-beta in the presence of IFN-gamma, and potentiated IFN-gamma-dependent positive transcriptional responses. In contrast to fibroblasts, in U4A cells lacking Jak1 and consequently unable to activate Stat1alpha-mediated responses, IFN-gamma failed to repress TGF-beta-induced transcription. These results indicate that as essential coactivators for both Smad3 and Stat1alpha, nuclear p300/CBP integrate signals that positively or negatively regulate COL1A2 transcription. The findings implicate a novel mechanism to account for antagonistic interaction of Smad and Jak-Stat pathways in regulation of target genes. In fibroblasts responding to cytokines with opposing effects on collagen transcription, the relative levels of cellular coactivators, and their interaction with regulated transcription factors, may govern the net effect.

Antineoplastic Agents↗
PubMed2000

Mutations of serine 236-237 and tyrosine 302 residues in the human lipoxin A4 receptor intracellular domains result in sustained signaling.

Lipoxin A(4) (LXA(4)) is a potent negative modulator of the inflammatory response. The antiinflammatory activities of LXA(4), such as inhibition of agonist-induced polymorphonuclear cell (PMN) chemotaxis and upregulation of beta-2 integrins, require the expression of a G-protein-coupled, high-affinity LXA(4) receptor (LXA(4)R). We now report that stimulation of PMN with proinflammatory agonist N-formyl peptides (FMLP), calcium ionophore A(23187), or phorbol mirystate acetate (PMA) is followed by marked downregulation of LXA(4) binding (B(max) decrease of approximately 45%) and decreased activation of phospholipases A(2) (PLA(2)) and D (PLD). Elucidation of the mechanisms underlying these effects was addressed by structure-function analyses of the intracellular domains of LXA(4)R. Mutant molecule, S236/S237 --> A/G (LXA(4)R(pk)) and Y302 --> F (LXA(4)R(tk)) were obtained by site-directed mutagenesis to yield receptors lacking the putative targets for serine/threonine kinase- or tyrosine kinase-dependent phosphorylation. Expression of wild-type and mutated LXA(4)R sequences in CHO and HL-60 cells was used to examine LXA(4) ligand-receptor interactions and signal transduction events. Results indicated that cells expressing LXA(4)R(pk) or LXA(4)R(tk) displayed sustained activation of PLA(2) and PLD in contrast to the transient ones obtained with LXA(4)R(wt) (peak activation at 2-3 min). Moreover, inhibition of LXA(4)-dependent PLA(2) activity by PMA in LXA(4)R(wt) transfected CHO cells was not observed in cells expressing LXA(4)R(pk). Phosphopeptide immunoblotting revealed that the functional differences between wild-type and mutant LXA(4) receptors are accompanied by distinct changes in the receptor protein phosphorylation pattern. Further characterization of these and related LXA(4)R intracellular domains will help to better understand specific events that regulate the antiinflammatory activities of LXA(4).

Animals↗
PubMed2000

Modulation of endogenous Smad expression in normal skin fibroblasts by transforming growth factor-beta.

Transforming growth factor-beta (TGF-beta) stimulation of collagen synthesis plays a fundamental role in physiological tissue repair as well as pathological fibrosis. Members of the SMAD family of intracellular proteins are phosphorylated by TGF-beta receptors and convey signals to specific TGF-beta-inducible genes. Ligand binding initiates signaling through the SMAD pathway, but it is unknown how signaling is terminated. The expression and regulation of Smads have been characterized mostly in transformed cells using transient expression systems. In this study, we investigated the physiological regulation of endogenous Smads by TGF-beta in nontransformed normal skin fibroblasts in vitro. Treatment with TGF-beta resulted in time- and dose-dependent translocation of SMAD3 and SMAD4 from the cytoplasm to the nucleus. The levels of SMAD3 and Smad3 mRNA were profoundly down-regulated by TGF-beta1 or TGF-beta3 in a time-dependent manner, whereas expression of antagonistic Smad7 was rapidly and transiently induced. The stability of Smad3 mRNA transcripts was unaffected by TGF-beta. Cycloheximide prevented the inhibition of Smad3, but not the induction of Smad7, mRNA expression by TGF-beta1, identifying Smad7 as an immediate-early gene target of TGF-beta in fibroblasts. In Smad4-deficient breast cancer cells, TGF-beta failed to modulate Smad expression, suggesting that SMADs mediate their own regulation in response to ligand. These results demonstrate that TGF-beta not only triggers functional activation of the SMAD signaling cascade in primary skin fibroblasts, but also simultaneously exerts potent effects on endogenous SMAD expression and intracellular trafficking. Taken together with recent reports implicating ubiquitination in SMAD turnover, these findings indicate the existence of multiple levels of control for modulating SMAD-mediated TGF-beta signaling in fibroblasts.

Adult↗
PubMed2000

Degradation of ochratoxin A by Aspergillus species.

Mycotoxin contamination of agricultural products is a serious health hazard throughout the world. Besides attempts to eliminate mycotoxins from contaminated substrates by physical and chemical methods, the ability of microbes to degrade mycotoxins is now being widely examined. In this study, several Aspergillus species were examined for their ability to degrade ochratoxin A. A. fumigatus and black Aspergillus strains were found to detoxify ochratoxin A in culture media. The kinetics of ochratoxin A detoxification by an atoxigenic A. niger strain was examined by thin layer chromatography, high-performance liquid chromatography and an immunochemical technique. A. niger CBS 120.49 was found to effectively eliminate ochratoxin A from both liquid and solid media, and the degradation product, ochratoxin alpha, was also decomposed.

Animals↗
PubMed2000

Smad-dependent stimulation of type I collagen gene expression in human skin fibroblasts by TGF-beta involves functional cooperation with p300/CBP transcriptional coactivators.

Transforming growth factor-beta (TGF-beta) stimulation of Type I collagen gene (COL1A2) transcription involves the Smad signal transduction pathway, but the mechanisms of Smad-mediated transcriptional activation are not fully understood. We now demonstrate that the ubiquitous transcriptional coactivators p300 and CREB-binding protein (CBP) enhanced basal as well as TGF-beta- or Smad3-induced COL1A2 promoter activity, and stimulated the expression of endogenous Type I collagen. The adenoviral E1A oncoprotein abrogated stimulation of COL1A2 activity in transfected fibroblasts, and reduced the basal level of collagen gene expression. This effect was due to specific interaction of E1A with cellular p300/CBP because (a) a mutant form of E1A defective in p300 binding failed to abrogate stimulation, and (b) forced expression of p300/CBP restored the ability of TGF-beta to stimulate COL1A2 promoter activity in the presence of E1A. The effect of p300 on COL1A2 transcription appeared to be due, in part, to its intrinsic acetyltransferase activity, as stimulation induced by a histone acetyltransferase-deficient mutant p300 was substantially reduced. Transactivation of COL1A2 by p300 involved the Smad signaling pathway, as Smad4-deficient cells failed to respond to p300, and stimulation was rescued by overexpression of Smad4. Furthermore, minimal constructs containing only the Smad-binding CAGACA element of COL1A2 were transactivated by p300 in the presence of TGF-beta. These results indicate, for the first time, that the multifunctional p300/CBP coactivators play a major role in Smad-dependent TGF-beta stimulation of collagen gene expression in fibroblasts. Oncogene (2000) 19, 3546 - 3555

Adenovirus E1A Proteins↗
PubMed2000

Lipoxin A4 inhibits IL-1 beta-induced IL-6, IL-8, and matrix metalloproteinase-3 production in human synovial fibroblasts and enhances synthesis of tissue inhibitors of metalloproteinases.

Lipoxins are a novel class of endogenous eicosanoid mediators that potently inhibit inflammatory events by signaling via specific receptors expressed on phagocytic cells. Animal models have shown that lipoxin A4 (LXA4) down-regulates inflammation in vivo. Here we demonstrate, for the first time, the expression of LXA4 receptors, and their up-regulation by IL-1 beta, in normal human synovial fibroblasts (SF). We examined whether exogenous LXA4 abrogated IL-1 beta stimulation of SF in vitro. IL-1 beta induced the synthesis of IL-6, IL-8, and matrix metalloproteinases (MMP)-1 and -3. At nanomolar concentrations, LXA4 inhibited these IL-1 beta responses with reduction of IL-6 and IL-8 synthesis, by 45 +/- 7% and 75 +/- 11%, respectively, and prevented IL-1 beta-induced MMP-3 synthesis without significantly affecting MMP-1 levels. Furthermore, LXA4 induced a 2-fold increase of tissue inhibitor of metalloproteinase (TIMP)-1 and a approximately 3-fold increase of TIMP-2 protein levels. LXA4 inhibitory responses were dose dependent and were abrogated by pretreatment with LXA4 receptor antiserum. LXA4-induced changes of IL-6 and TIMP were accompanied by parallel changes in mRNA levels. These results indicate that LXA4 in activated SF inhibits the synthesis of inflammatory cytokines and MMP and stimulates TIMP production in vitro. These findings suggest that LXA4 may be involved in a negative feedback loop opposing inflammatory cytokine-induced activation of SF.

Cells, Cultured↗
PubMed2000

Interaction of smad3 with a proximal smad-binding element of the human alpha2(I) procollagen gene promoter required for transcriptional activation by TGF-beta.

Transcription of the alpha2(I) collagen gene (COL1A2) in fibroblasts is potently induced by transforming growth factor-beta (TGF-beta). Smad family proteins function as intracellular signal transducers for TGF-beta that convey information from the cell membrane to the nucleus. In the present study, we establish the functional requirement for endogenous Smad3 and Smad4 in TGF-beta-stimulated COL1A2 transcription in human skin fibroblasts in vitro. Furthermore, using transfections with a series of 5' deletions of the human COL1A2 promoter, we identify a proximal region between -353 and -148 bp, which is required for full stimulation of transcription by a constitutively active TGF-beta type I receptor. This region of the COL1A2 promoter contains a CAGA motif also found in the promoter of the plasminogen activator inhibitor-1. Substitutions disrupting this sequence decreased the binding of nuclear extracts or recombinant Smad3 to the CAGACA oligonucleotide, and markedly reduced the transcriptional response to TGF-beta or overexpressed Smad3 in transient transfection assays. The insertion of tandem repeats of CAGACA conferred TGF-beta stimulation to a heterologous minimal promoter-reporter construct. Inhibition of endogenous Smad expression in fibroblasts by antisense oligonucleotides or cDNA against Smad3 or Smad4, and transfection of COL1A2 promoter constructs into Smad4-deficient breast adenocarcinoma cells, indicated the critical role of Smads for the full TGF-beta response. The importance of Smad binding to the CAGACA box of COL1A2 was further established by transcriptional decoy oligonucleotide competition. Taken together, the results identify a functional Smad-binding element of the COL1A2 promoter harboring a CAGACA consensus sequence that is both necessary and sufficient for stimulation by TGF-beta, and demonstrate that interaction of this Smad-binding element with endogenous Smads is required for the full TGF-beta response in fibroblasts.

Adenocarcinoma↗
PubMed2000

Skin thickness score as a predictor and correlate of outcome in systemic sclerosis: high-dose versus low-dose penicillamine trial.

OBJECTIVE: To study the clinical implications of a skin thickness score > or =20 at first visit and of softening of sclerodermatous skin in a cohort of systemic sclerosis (SSc) patients with diffuse cutaneous scleroderma. METHODS: Skin and visceral involvement were assessed in 134 SSc patients with diffuse scleroderma (mean +/- SD duration of SSc 10 +/- 4 months) as they entered a multicenter drug trial and again at 2 years of followup. Advent of mortality and scleroderma renal crisis (SRC) were assessed during a followup of 4.0 +/- 1.1 years (mean +/- SD). Logistic and linear regression were used to examine the relationship of baseline skin score to morbidity, mortality, and visceral involvement and the relationship of changes in skin score to changes in physical examination, laboratory, and functional variables over 2 years. RESULTS: A baseline skin score > or =20 was associated with heart involvement at baseline (odds ratio [OR] 3.10, 95% confidence interval [95% CI] 1.25-7.70) and was predictive of mortality (OR 3.59, 95% CI 1.23-10.55) and SRC (OR 10.00, 95% CI 2.21-45.91) over 4 years. Multivariate linear regression demonstrated that a model with skin score at baseline (P = 0.0078) and changes in large joint contractures (P = 0.0072), tender joint counts (P = 0.0119), handspread (P = 0.0242), and Health Assessment Questionnaire disability index (HAQ-DI) (P = 0.0244) explained the change in skin score over 2 years (R2 = 0.567). Multivariate logistic regression demonstrated that the investigator's global assessment of improvement was best explained by a model with skin score and HAQ-DI (R2 = 0.455). CONCLUSION: A baseline skin score > or =20 was associated with heart involvement at baseline and predicted mortality and SRC over the subsequent 4 years. Improvement in skin score in these patients with diffuse cutaneous scleroderma was associated with improvement in hand function, inflammatory indices, joint contractures, arthritis signs, overall functional ability, and the examining investigator's global assessment of improvement.

Adult↗
PubMed2000

Phylogenetic analysis of Aspergillus section Circumdati based on sequences of the internal transcribed spacer regions and the 5.8 S rRNA gene.

Phenotypic features and sequences of the internal transcribed spacer (ITS) regions and the 5.8 S rRNA gene of type or neotype strains and other isolates of the 17 species currently assigned to Aspergillus section Circumdati and some potentially related species were analyzed. Parsimony analysis of sequence data indicated that Aspergillus section Circumdati is paraphyletic. Aspergillus campestris, A. lanosus, and A. dimorphicus with A. sepultus were found to be more closely related to Aspergillus sections Candidi, Flavi, and Cremei, respectively. These results were also supported by phenotypic data. A. robustus and A. ochraceoroseus were found not to be related to any of the species examined. Species of the proposed revised Aspergillus section Circumdati formed two main clades, which could also be distinguished based on phenotypic methods. Phylogenetic analysis of sequence data of other isolates assigned to species of the revised section indicates that either some of these isolates were misidentified or species concepts of A. ochraceus, A. melleus, and A. petrakii should be reconsidered.

Aspergillus↗
PubMed2000

Genetic variability within the Aspergillus viridinutans species.

The intraspecific variability of the Aspergillus viridinutans species was examined using various techniques including morphological examinations, carbon-source-utilization tests, restriction-enzyme analysis of the mitochondrial and nuclear DNA, and sequence analysis of part of the beta-tubulin gene. Although the genetic distances between the isolates were higher than between, e.g., A. fumigatus and Neosartorya fischeri, most A. viridinutans isolates, together with N. aureola and N. udagawae strains, were found to belong to a single cluster based on sequence data. Strain FRR 1266, which was earlier classified as a highly divergent A. fumigatus isolate, was found to belong to the A. viridinutans species. The ochratoxin A producing A. viridinutans strain IMI 306135 was most closely related to an asexual isolate. These two latter strains were more closely related to A. fumigatus and N. fischeri than to any A. viridinutans strains, and possibly represent a new species in the Aspergillus section Fumigati. The dendrogram based on carbon source utilization data and results of restriction analysis of the mitochondrial and nuclear DNA of the strains supported most of the evolutionary relationships observed on the basis of sequence data. The results indicate that the presence or absence of nodding conidial heads is not an unequivocal morphological character for the identification of species within the Aspergillus section Fumigati.

Animals↗
PubMed2000

Analysis of genetic variability within the genus Petromyces.

Phenotypic and genotypic features of three teleomorphic species, Petromyces alliaceus, P. albertensis and P. muricartus and some related anamorphic Aspergillus species were compared. The dendrogram based on carbon source utilisation data revealed a close relationship between P. muricarus and the A. ochraceus strains examined. P. alliaceus and P. albertensis strains were very closely related to each other. A dendrogram with similar topology was obtained by analysing sequences of the intergenic transcribed spacer regions of representatives of these species. P. alliaceus and P. albertensis strains could only be distinguished by the random amplified polymorphic DNA technique. These strains possibly represent a single species closely related to Aspergillus section Flavi, while the anamorph of P. turicatus is a member of Aspergillus section Circumdati. Our results indicate that Aspergillus section Circumdati is in need of taxonomic revision.

Ascomycota↗
PubMed2000

Phylogenetic analysis of newly described Neosartorya species.

Isolates representing newly described Neosartorya species, and isolates with abnormal morphologies from Aspergillus section Fumigati were examined by phylogenetic analysis of sequences of part of their beta-tubulin gene. Phylogenetic analyses supported the earlier suggestions that heterothallism is a derived character, and that sexuality was lost several times during the evolution of Aspergillus section Fumigati. The heterothallic N. fennelliae and N. udagawae strains were found to be closely related to the homothallic Neosartorya sp. NRRL 4179 and N. aureola, respectively. Aspergillus sp. FRR 1266, which was earlier described as a variant of A. fumigatus, was found to be closely related to A. viridinutans. Another abnormal asexual isolate was found to be closely related to A. fumigatus and N. fischeri. Phylogenetic relationships among newly described Neosartorya species and other taxa were successfully established based on phylogenetic analysis of beta-tubulin sequences.

DNA, Fungal↗
PubMed2000

Eosinophil granule-derived major basic protein induces IL-8 expression in human intestinal myofibroblasts.

Eosinophil infiltration occurs in a variety of allergic and inflammatory diseases. The release of preformed mediators from eosinophils may contribute to inflammatory responses. We investigated the ability of eosinophil-derived major basic protein and eosinophil-derived neurotoxin to stimulate production of IL-8 from intestinal myofibroblasts. Intestinal myofibroblasts (18-Co cells) were incubated with major basic protein, eosinophil-derived neurotoxin, or a synthetic analogue of major basic protein, poly-L-arginine. Immunoreactive IL-8 was measured by ELISA and IL-8 mRNA levels were analysed by Northern blot or reverse transcription-polymerase chain assay. Major basic protein induced IL-8 mRNA production and release of significant levels of IL-8 immunoreactive protein. By contrast, eosinophil-derived neurotoxin stimulated little IL-8 release. The induction of IL-8 mRNA by poly-L-arginine was significantly inhibited by actinomycin D. These findings demonstrate a novel interaction between eosinophils and intestinal fibroblasts that may be involved in the pathogenesis of diseases associated with tissue eosinophilia.

Blood Proteins↗
PubMed2000

Efficacy evaluations of the use of oral tilmicosin in pneumonic calves.

The therapeutic effect of oral tilmicosin was compared with enrofloxacin, and the efficacy of three doses of the drug was examined in two fully randomized blinded field trials. Pneumonic milk-fed calves between 3 days and 2.5 months of age were allocated into two groups in trial 1 (50 animals) and into three groups in trial 2 (69 calves). In the first trial, the animals were treated with 25 mg/kg/day tilmicosin or 2.5 mg/kg/day enrofloxacin in milk for 5 days. In the second trial, the calves received either 25 mg/kg/day tilmicosin for 5 days or 3 days, or else 12.5 mg/kg tilmicosin for 5 days. All calves were clinically examined for 10 days. In the first trial, oral tilmicosin at a dose of 25 mg/kg/day for 5 days proved to be effective for the treatment of endemic pasteurellosis of milk-fed calves. The efficacy was the same as that of enrofloxacin. All three doses in the second trial were effective and were statistically equivalent to the original dose tested.

Administration, Oral↗
PubMed2000

The clinical usefulness of the fingers-to-palm ratio in different hand microcirculatory abnormalities.

A non-invasive nuclear medicine technique was developed to screen patients with painful hands so as to separate patients with a normal from those with an abnormal microcirculation of the hands in different clinical conditions. Such a technique is important, as the other methods available are either subjective or rather complicated. The study population consisted of 10 healthy individuals, 23 patients with Raynaud's syndrome and 15 patients with mixed connective tissue disease (MCTD). Sixty gamma-camera images of the hands (1 s each) were recorded after a bolus injection of 99Tcm-DTPA via a dorsal foot vein. Regions of interest were drawn on the summed images around the fingers and the palmar region. The fingers-to-palm ratio was then calculated from the total counts inside these regions of interest separately for each hand. The mean fingers-to-palm ratio was 0.94+/-0.18 (0.71-1.25) for the healthy group, 0.57+/-0.22 (0.21+/-1.11) for the MCTD group and 0.40+/-0.14 (0.18-0.77) for the Raynaud's patients. Analysis of variance showed these differences to be highly significant (P < 0.001). There were also significant differences between 6 MCTD patients in an active (mean 0.48) and nine patients in an inactive (mean 0.66) clinical state (two-sample t-test: P < 0.05). There were no significant differences between the fingers-to-palm ratios of the left and right hands of the same patients (one-sample t-test). Of the 23 primary Raynaud's patients, capillary microscopic data were pathological in only eight (34%). We conclude that our method is able to differentiate between patients with normal and those with abnormal microcirculation of the hands. Although measurement of the fingers-to-palm ratio is not a specific method, it is useful both for staging and in the follow-up of patients.

Adolescent↗