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J Abel

Publications and source records attributed to J Abel.

At least 37 records · Page 2Linked to original sources
PubMed2000

mRNA expression patterns in different stages of asbestos-induced carcinogenesis in rats.

Human malignant mesotheliomas are induced almost exclusively by fibrous dusts. The nature of interactions between fibers and target cells, and the molecular mechanisms leading to tumorigenesis, are not yet understood. Here, the mRNA expression patterns at different stages of asbestos-induced carcinogenesis in rats were monitored by suppression subtractive hybridization (SSH) and array assay. Several genes were upregulated in pretumorous tissues from asbestos-treated rats, in asbestos-induced tumors and in cells treated with asbestos in vitro. The upregulation of the proto-oncogene c-myc, fra-1 and egfr in fiber-induced carcinogenesis was demonstrated at different stages of carcinogenesis. A possible role of Fra-1 as one of the dimeric proteins generating the AP-1 transcription factor was substantiated by its dose-dependent expression in mesothelial cells treated with asbestos in vitro. The upregulation of osteopontin (an extracellular matrix protein) and of zyxin and integrin-linked kinase (intracellular proteins associated with the focal adhesion contact), indicate that fibers may affect integrin-linked signal transduction and extracellular matrix proteins.

Animals↗
PubMed1999

Transforming growth factor-beta1 inhibits expression of selenoprotein P in cultured human liver cells.

The effect of cytokines on the expression of selenoprotein P (SeP) in the human liver cell line HepG2 was investigated. Treatment with interleukin-1beta, interferon-gamma, and tumor necrosis factor-alpha had no effect on SeP levels in culture media or on SeP mRNA expression. Conversely, Western analysis revealed a dose-dependent reduction of SeP content in culture medium after treatment with transforming growth factor (TGF)-beta1 with an 1C50 of 31 pM. Treatment with 100 pM TGF-51 for 48 h led to a decrease to 21 +/- 9% of controls. RT-PCR analysis of SeP mRNA expression demonstrated an inhibition of SeP transcription to 40+/-2% of control levels after 24 h. The expression of a luciferase reporter construct under control of the human SeP promoter was downregulated by TGF-beta1 treatment in a dose-dependent fashion indicating a transcriptional regulation of the SeP gene by TGF-beta1.

Cycloheximide↗
PubMed1999

Polymorphisms of the xenobiotic-metabolizing enzymes CYP1A1 and NAT-2 in systemic sclerosis and lupus erythematosus.

The etiology of systemic autoimmune diseases, such as systemic lupus erythematosus (SLE) and systemic sclerosis (SSc) is still unknown. In several cases, however, xenobiotics (i.e. drugs and occupational agents) were identified as etiologic agents and associations with certain polymorphic alleles of xenobiotic-metabolizing enzymes have been reported. Cytochrome P4501A1 (CYP1A1) and N-acetyltransferase 2 (NAT-2) are xenobiotic-metabolizing enzymes of phase 1- and phase 2-metabolism, respectively. CYP1A1 may activate drugs and other chemicals to reactive metabolites. NAT-2 is the most important enzyme in acetylation of aromatic amines, and thus may be responsible for detoxification of many of these compounds. Two polymorphisms of the human CYP1A1 gene, a point mutation in the 3' flanking region of the gene (Msp1) and a mutation in exon 7 leading to an isoleucine-valine-exchange in the heme-binding region of the enzyme, have been described and may lead to a higher basal and inducible enzyme activity. With respect to NAT-2, several alleles which combine for the two phenotypes "fast" and "slow" acetylators have been described. We analyzed the gene frequencies of the CYP1A1 polymorphisms and the phenotypes of NAT-2 in patients suffering from idiopathic SLE or SSc. CYP1A1 polymorphisms were analyzed in genomic DNA by PCR, whereas NAT-2 phenotypes were measured by the caffeine method. For CYP1A1 polymorphisms, 106 patients have been typed until now. The SLE group (n = 68) exhibited a significant increase (p < 0.05) in the mutant Val-allele (OR = 2.59) when compared to controls (n = 184). However, no significant differences in allele frequencies for MspI in the SLE group and for both CYP1A1 polymorphisms in the SSc group could be observed. Regarding the NAT-2 phenotype, patients suffering from SLE (n = 88) 75% and SSc (n = 26) 80.2%, respectively, were slow acetylators compared to 55% slow acetylators in the healthy German population (p < 0.05). The observed increased frequencies of the CYP1A1 mutant Val-allele and the slow actylator phenotype in idiopathic autoimmune disease support our concept that in slow acetylators non-acetylated xenobiotics may accumulate and are subsequently metabolized by other enzymes into reactive intermediates. Thus, enhanced formation of reactive metabolites could alter self-proteins presented to the immune system thus stimulating autoreactive T cells which induce autoimmunity.

Alleles↗
PubMed1999

Real-time PCR-analysis of the cytochrome P450 1B1 codon 432-polymorphism.

The aim of the present study was to develop and validate a rapid assay for genotyping of CYP1B1 codon 432-polymorphism. The described method is a single tube assay and combines both rapid-cycle polymerase chain reaction (PCR) with real-time monitoring by amplification and generation of the melting profiles of an allele-specific fluorescent probe. With this method 300 samples were analysed from healthy, unrelated Germans. Genotype frequency determined for the mutated allele CYP1B1*2 was 0.40. The results show that genotyping of CYP1B1 codon 432-polymorphism with a real-time fluorescence PCR method is a rapid and reliable assay for the analysis of large numbers of samples.

Alleles↗
PubMed1999

Procainamide, a drug causing lupus, induces prostaglandin H synthase-2 and formation of T cell-sensitizing drug metabolites in mouse macrophages.

Procainamide (PA) may cause drug-induced lupus, and its reactive metabolites, hydroxylamine-PA (HAPA) and nitroso-PA, are held responsible for this. Here, we show that N-oxidation of PA to these metabolites can take place in macrophages and lead to formation of neoantigens that sensitize T cells. Murine peritoneal macrophages (PMvarphi), exposed to PA in vitro, generated neoantigens related to HAPA as indicated by (1) their capacity to elicit a specific recall response of HAPA-primed T cells in the adoptive transfer popliteal lymph node (PLN) assay and (2) the appearance of metabolite-bound protein in PA-pulsed PMvarphi, as determined by Western blot. Analysis of five phase I enzymes that might be responsible for HAPA formation by PMvarphi pointed to prostaglandin H synthase-2 (PGHS-2) as a likely candidate. Experimental evidence that PA can be oxidized to HAPA by PGHS was obtained by exposing PA to PGHS in vitro. The resulting metabolites were identified by mass spectral analysis and covalent protein binding in ELISA. In vitro, PA exposure of PMvarphi of slow acetylator A/J and fast acetylator C57BL/6 mice failed to show significant strain differences in enzyme mRNA expression, enzyme activities, or formation of HAPA-related neoantigens. By contrast, after long-term PA treatment in vivo only in slow acetylators the PMvarphi harbored HAPA-related neoantigens and T cells were sensitized to them. PMvarphi of fast acetylator C57BL/6 mice only contained HAPA-related neoantigens, and their T cells were only sensitized to them if, in addition to long-term PA treatment, their donors had received injections of phorbol myristate acetate (PMA), a known enhancer of oxidative enzymes in phagocytes. In conclusion, PA treatment leads to N-oxidation of PA by enzymes, in particular PGHS-2, present in antigen-presenting cells (APC) and, hence, to generation of neoantigens which sensitize T cells. The enhanced neoantigen formation and T cell sensitization seen in slow acetylators might be explained by their higher concentration of PA substrate that is available for extrahepatic N-oxidation in APC.

Animals↗
PubMed1999

A malignant transformation of human cells by 2,3,7,8-tetrachlorodibenzo-p-dioxin exhibits altered expressions of growth regulatory factors.

The neoplastic transformation of human cells in culture with exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) has recently been reported. In this study, expressions of growth regulatory factors were analyzed to examine their possible roles in TCDD-induced malignant transformation of human cells. Reverse transcription-polymerase chain reaction (RT-PCR) and immunoblot analysis were performed to detect altered expressions of genes associated with dioxin responses. The RT-PCR analysis showed that expressions of the growth regulatory factors, such as transforming growth factor-beta1 (TGF-beta1), plasminogen activator inhibitor-2 (PAI-2) and tumor necrosis factor-alpha (TNF-alpha), were significantly changed in the transformed cells as compared with the parental cells. Whereas parental cells showed a dose-dependent increase of PAI-2 mRNA levels following TCDD exposure, the transformed cells did not show any significant induction. In addition, constitutive levels of PAI-2 mRNA were 25 times lower in the transformed cells than in the parental cells. The mRNA stability assay suggests that downregulation of PAI-2 mRNA in the transformed cells may be associated with the posttranscriptional control. Expression of TGF-beta1 mRNA in the transformed cells was also four times lower than the parental cells. However, levels of TNF-alpha mRNA in the transformed cells were increased 3-fold. These results suggest that dysregulation of growth regulatory factors may be involved in TCDD-induced cellular transformation. Whereas plenty of studies demonstrated a number of immediate toxic effects by TCDD, this study revealed an initial evidence that altered expression of growth regulatory genes, such as PAI-2, TGF-beta1 or TNF-alpha, are some of the genetic events fixed in the genome following the successive cell divisions of TCDD-damaged cells. It is suggested that these changes may be associated with TCDD-induced malignant transformation of human cells.

Aryl Hydrocarbon Receptor Nuclear Translocator↗
PubMed1998

A novel method for the purification of selenoprotein P from human plasma.

Selenoprotein P was purified from human plasma using conventional chromatographic methods featuring metal-chelate-affinity chromatography as the final step. Two distinct isoforms with different selenium content were isolated and identified by N-terminal sequencing and immunoblot analysis. Their molecular mass is 61 and 51 kDa, respectively. Both isoforms could be detected in fresh plasma from five individuals. This rules out the possibility of the second isoform being an artifact which results from degradation of full-length selenoprotein P during purification.

Blood Proteins↗
PubMed1998

Modulation of prostaglandin H synthase-2 mRNA expression by 2,3,7,8-tetrachlorodibenzo-p-dioxin in mice.

Prostaglandin endoperoxide H synthases (PGHS-1 and PGHS-2) catalyze an intermediate step in the biosynthesis of prostaglandins and thromboxanes. Recently, it was observed that 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) modulates the expression of PGHS-2 mRNA in different cell lines. The main aim of this study was to examine whether PGHS-2 mRNA expression can be changed by acute TCDD in vivo and, second, we were also interested in whether modulation of PGHS-2 is mediated by the aryl hydrocarbon receptor (AhR) which is known to be involved in the transcriptional control of TCDD-induced phase 1 and phase 2 enzymes. Initially C57BL/6J mice were treated with a single dose of 10,000 ng TCDD/kg and the PGHS-1 and PGHS-2 mRNAs were analyzed in liver, lung, thymus, kidney, and spleen. In all tissues examined the expression of PGHS-1 mRNA was not affected by TCDD. However, TCDD treatment enhanced the PGHS-2 mRNA levels in lung and spleen. No effect of TCDD on PGHS-2 expression was found in liver and kidney. For dose-response studies C57BL/6J and DBA/2J mice were treated for 24 h with various doses of TCDD (1-50,000 ng/kg) and the PGHS-2 mRNA increases were analyzed in lungs and spleens. A significant increase of PGHS-2 mRNA in lungs of C57BL/6J mice was found at a dose of 100 ng TCDD/kg, whereas a nearly 100-fold higher TCDD dose was needed to increase PGHS-2 in DBA/2J mice. A similar dose-dependent induction of PGHS-2 was found in spleens of C57BL/6J mice; however, no significant increase of PGHS-2 was found in spleens of DBA/2 mice. These results indicate an involvement of AhR in TCDD-mediated changes of PGHS-2 expression. This suggestion is supported by studies in AhR-deficient animals which showed that TCDD had no effect on PGHS-2 mRNA. When changes of PGHS-2 mRNA expression are compared with those of CYP1A1 between 4 and 72 h after TCDD, it is noteworthy that TCDD led to a delayed and more transient increase of PGHS-2. These data suggest that the mechanism of modulation of both genes by TCDD may be different.

Animals↗
PubMed1998

The diagnostic importance of eosinophil granulocytes in the CSF of children with ventricular-peritoneal shunt systems.

We investigated the occurrence of cerebrospinal fluid (CSF) eosinophilia in patients with ventriculo-abdominal shunt systems with regard to possible infection. For this purpose, we examined the CSF of 83 children at the time of shunt obstruction or malfunction. In 32 children (38.6%) we found more than 4% of eosinophil granulocytes in the CSF with a maximum of 76%. In 15 of these 32 children the CSF was sterile, whereas in 17 patients bacterial infection was present. In the CSF of 16 of those 17 children, Staph. epidermidis was cultivated. There was statistically significant correlation between positive Staph. epidermidis culture and the occurrence of CSF eosinophilia (P<0.05). The occurrence of CSF eosinophilia in patients with ventriculo-peritoneal shunts is well known and was mostly attributed to an allergic reaction. Our findings support the theory of an infectious etiology of the eosinophilia and are thus in line with new American and French studies. We believe that CSF eosinophilia indicates a persistent infection of the central nervous system by the contaminated shunt system. As the organism which is the most common cause we cultured Staph. epidermidis.

Child↗
PubMed1997

Transforming growth factor-beta1 coregulates mRNA expression of aryl hydrocarbon receptor and cell-cycle-regulating genes in human cancer cell lines.

Transforming growth factor (TGF)-beta1 down-regulates mRNA expression of the aryl hydrocarbon receptor (AhR) and of AhR-inducible genes in A549 cells. Here, we describe a dose-dependent inhibition of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-induced cytochrome P450 (CYP) 1A1, CYP1B1 and NADPH-quinone-oxidoreductase (NMO-1) mRNA expression as well as TCDD-induced 7-ethoxyresorufin-O-deethylase (EROD) activity in MDA-MB 231 cells. The AhR mRNA expression was not affected by TGF-beta1. TGF-beta-responsiveness was investigated by examining the effect on the expression of responsive genes. While TGF-beta1 up-regulates mRNA expression of TGF-beta1 and TIEG (TGF-beta-inducible early gene) as well as luciferase activity of a responsive reporter plasmid in both cell lines, a down-regulation of c-myc and cyclin A mRNA expression was only found in A549 cells. Furthermore, TGF-beta1 inhibits only cell proliferation of A549 but not of MDA-MB 231 cells. The results show a coregulation of mRNA expression of AhR and cell-cycle regulating genes, and further indicate that the AhR may be involved in regulation of cell proliferation.

Aryl Hydrocarbon Hydroxylases↗
PubMed1997

Usefulness of coronary stenting for cardiogenic shock.

Coronary stenting was performed in 15 selected patients with cardiogenic shock, with favorable clinical and angiographic outcomes. This experience suggests that coronary stenting may play an important adjunctive role in the management of cardiogenic shock and may improve outcome beyond that achieved with balloon angioplasty alone.

Aged↗
PubMed1997

Effect of subchronic 2,3,7,8-tetrachlorodibenzo-p-dioxin exposure on immune system and target gene responses in mice: calculation of benchmark doses for CYP1A1 and CYP1A2 related enzyme activities.

The dose-effect relationships were analysed for several noncarcinogenic endpoints, such as immunological and biochemical responses at subchronic, low dose exposure of female C57BL/6 mice to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). The animals were treated i.p. with TCDD according to the initial- and maintenance-dose principal for a period of 135 days. The initial doses were 1, 10 and 100 ng TCDD/kg, the weekly maintenance doses were 0.2, 2 and 20 ng TCDD/kg, respectively. At days 23, 79 and 135 of TCDD/kg, treatment 10 animals of each dose group were killed. As immunological parameters the number of thymocytes and the pattern of thymocyte subpopulations were determined. In liver, lung and thymus, mRNA expression of TGF-alpha, TGF-beta(1), TGF-beta(2), TGF-beta(3), TNF-alpha, IL-1 beta and different CYP1 isoforms (CYP1A1, CYP1A2, CYP1B1) was analysed. In the livers, activities of 7-ethoxyresorufin-O-deethylase (EROD) and 7-methoxyresorufin-O-demethylase (MROD) were measured. TCDD content in the liver was determined. The main results are summarized as follows: (1) The TCDD doses were not sufficient to elicit dose-dependent changes of pattern of thymocyte subpopulation. (2) TCDD failed to change the mRNA expression of TGF-alpha, TGF-beta and TNF-alpha, but led to an increase of IL-1 beta mRNA expression in liver, lung and thymus. The results show that the TCDD induced IL-1 beta mRNA increase is at least as sensitive a marker as the induction of CYP1A isoforms. (3) The expression of CYP1B1 mRNA remained unchanged at the doses tested, while CYP1A1 and CYP1A2 mRNA expression was dose-dependently enhanced. EROD and MROD activities in the liver paralleled the increases of CYP1A1 and CYP1A2 mRNA expression. (4) Regression analysis of the data showed that most of the parameters tested fit a linear model. (5) From the data, a benchmark dose for EROD/MROD activities in the livers of female C57BL/6 mice of about 0.03 ng TCDD/kg per day was calculated.

Animals↗
PubMed1997

Reliability audit of a regional cardiac surgery registry.

OBJECTIVE: The British Columbia Provincial Cardiac Registry collects demographic and clinical data on all patients who undergo cardiac surgery procedures in the province. The purpose of this study was to compare the reliability of data contained in Registry with data contained in hospital charts. METHODS: Registry and hospital charts were compared for 480 cases. Thirty cases were randomly selected for the province's 16 cardiac surgeons. For each case, 10 distinct fields were selected for analysis and classified as consistent, inconsistent, or rejected (data unavailable in one or other source). RESULTS: The overall rate of consistency between charts and the Registry was 86.4%, with an inconsistency rate of 9.9% and a rejection rate of 3.7%. Consistency rates varied significantly across the 10 fields and among the 16 surgeons. Pairwise comparisons of rates between fields indicated that specific field types were problematic and should be targeted for improvement. In addition, pairwise comparisons of rates between surgeons indicated that further education on Registry use is required. CONCLUSIONS: Recommendations for database design and management include provision of standard definitions for all fields; education of users; extension of the number of mandatory fields; revision of check-off box fields to yes/no/unsure fields; and collection of data close to the time that it is generated.

British Columbia↗
PubMed1997

Effect of transforming growth factor-beta1 on expression of aryl hydrocarbon receptor and genes of Ah gene battery: clues for independent down-regulation in A549 cells.

An inhibitory effect on both constitutive and inducible expression of cytochrome P450 isoenzymes has been shown for different cytokines and growth factors. We previously described an inhibition of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-induced CYP1A1 mRNA and enzyme activity by transforming growth factor-beta1 (TGF-beta1) in human lung cancer A549 cells. In the present study, we report that not only TCDD-induced expression of CYP1A1 but also basal mRNA expression of CYP1A1, CYP1B1, and aryl hydrocarbon receptor (AHR) was down-regulated by TGF-beta1 in cells not treated with TCDD. In contrast, mRNA expression of the AHR partner protein Arnt (aryl hydrocarbon receptor nuclear translocator) was not influenced. Furthermore, TCDD-induced expression of CYP1B1 and NMO-1 was inhibited, and the IC50 values of 5-10 pM TGF-beta1 were in the same range as observed for inhibition of CYP1A1 and AHR mRNA expression. Transfection studies with a plasmid containing a luciferase reporter gene under control of two dioxin-responsive elements indicate an effect on AHR protein expression. Results of time-course studies revealed a parallel inhibition of AHR and CYP1 mRNA expression, indicating that TGF-beta1 is a direct negative regulator of transcription of these genes. The treatment of cells with cycloheximide led to a superinduction of TCDD-induced CYP1A1 and CYP1B1 mRNA expression and abolished the inhibitory effect of TGF-beta1 on basal as well as TCDD-induced CYP1 and AHR mRNA expression. TGF-beta1 seems not to influence the stability of AHR mRNA. The results suggest that TGF-beta1 induces rapid transcription and translation of an as-yet-unknown negative regulatory factor or factors that may directly regulate expression of AHR and genes of Ah gene battery.

Cell Line↗