Pulmonary arteriovenous malformation in two adult alpacas (Vicugna pacos)

Two cases of pulmonary vascular anomaly in unrelated adult alpacas (Vicugna pacos) are described. In the first case, a 9-year-old intact male alpaca presented at Oregon State University Veterinary Teaching Hospital with bilateral epistaxis and died the subsequent day following severe hemorrhage from the mouth and nostrils. At necropsy, a tortuous vascular lesion was identified in the right cranial lung lobe, associated with hemorrhage into airways. In the second case, a 2-year-old female alpaca presented with postpartum anorexia, opisthotonus, and recumbency. In this second case, a similar vascular lesion was identified in the right cranial lung lobe but without associated hemorrhage. Histopathological examination of the lesion in both cases revealed numerous dilated, irregular blood vessels with marked variation in wall thickness within vessels, surrounded by foci of extramedullary hematopoiesis. Diagnoses of locally extensive pulmonary vascular anomalies (arteriovenous malformations) were made.Keywords: Arteriovenous fistula, Lung, Histopathology, Vicugna pacos, Alpacas, Epistaxi

Transplacental Carcinogenesis with Dibenzo[def,p]chrysene (DBC): Timing of Maternal Exposures Determines Target Tissue Response in Offspring

Dibenzo[def,p]chrysene (DBC) is a transplacental carcinogen in mice (15 mg/kg; gestation day (GD) 17). To mimic residual exposure throughout pregnancy, dams received 4 smaller doses of DBC (3.75 mg/kg) on GD 5, 9, 13 and 17. This regimen alleviated the previously established carcinogenic responses in the thymus, lung, and liver. However, there was a marked increase in ovarian tumors (females) and hyperplastic testes (males). [¹⁴C]-DBC (GD 17) dosing revealed transplacental distribution to fetal tissues at 10-fold lower concentrations than in paired maternal tissue and residual [¹⁴C] 3 weeks post dose. This study highlights the importance of developmental stage in susceptibility to environmental carcinogens.This is the author's peer reviewed final manuscript as accepted by the publisher. The published article is copyrighted by Elsevier and can be found here: http://www.elsevier.com/wps/find/journaldescription.cws_home/506050/description#descriptio

Coibamide A Induces mTOR-Independent Autophagy and Cell Death in Human Glioblastoma Cells

Coibamide A is an N-methyl-stabilized depsipeptide that was isolated from a marine cyanobacterium as part of an International Cooperative Biodiversity Groups (ICBG) program based in Panama. Previous testing of coibamide A in the NCI in vitro 60 cancer cell line panel revealed a potent anti-proliferative response and "COMPARE-negative" profile indicative of a unique mechanism of action. We report that coibamide A is a more potent and efficacious cytotoxin than was previously appreciated, inducing concentration-and time-dependent cytotoxicity (EC₅₀<100 nM) in human U87-MG and SF-295 glioblastoma cells and mouse embryonic fibroblasts (MEFs). This activity was lost upon linearization of the molecule, highlighting the importance of the cyclized structure for both anti-proliferative and cytotoxic responses. We show that coibamide A induces autophagosome accumulation in human glioblastoma cell types and MEFs via an mTOR-independent mechanism; no change was observed in the phosphorylation state of ULK1 (Ser-757), p70 S6K1 (Thr-389), S6 ribosomal protein (Ser-235/236) and 4EBP-1 (Thr-37/46). Coibamide A also induces morphologically and biochemically distinct forms of cell death according to cell type. SF-295 glioblastoma cells showed caspase-3 activation and evidence of apoptotic cell death in a pattern that was also seen in wild-type and autophagy-deficient (ATG5-null) MEFs. In contrast, cell death in U87-MG glioblastoma cells was characterized by extensive cytoplasmic vacuolization and lacked clear apoptotic features. Cell death was attenuated, but still triggered, in Apaf-1-null MEFs lacking a functional mitochondria-mediated apoptotic pathway. From the study of ATG5-null MEFs we conclude that a conventional autophagy response is not required for coibamide A-induced cell death, but likely occurs in dying cells in response to treatment. Coibamide A represents a natural product scaffold with potential for the study of mTOR-independent signaling and cell death mechanisms in apoptotic-resistant cancer cells

Comparative benefits and harms of second generation antidepressants and cognitive behavioral therapies in initial treatment of major depressive disorder: systematic review and meta-analysis

Study question What are the benefits and harms of second generation antidepressants and cognitive behavioral therapies (CBTs) in the initial treatment of a current episode of major depressive disorder in adults?Methods This was a systematic review including qualitative assessment and meta-analyses using random and fixed effects models. Medline, Embase, the Cochrane Library, the Allied and Complementary Medicine Database, PsycINFO, and the Cumulative Index to Nursing and Allied Health Literature were searched from January1990 through January 2015. The 11 randomized controlled trials included compared a second generation antidepressant CBT. Ten trials compared antidepressant monotherapy with CBT alone; three compared antidepressant monotherapy with antidepressant plus CBT.Summary answer and limitations Meta-analyses found no statistically significant difference in effectiveness between second generation antidepressants and CBT for response (risk ratio 0.91, 0.77 to 1.07), remission (0.98, 0.73 to 1.32), or change in 17 item Hamilton Rating Scale for Depression score (weighted mean difference, −0.38, −2.87 to 2.10). Similarly, no significant differences were found in rates of overall study discontinuation (risk ratio 0.90, 0.49 to 1.65) or discontinuation attributable to lack of efficacy (0.40, 0.05 to 2.91). Although more patients treated with a second generation antidepressant than receiving CBT withdrew from studies because of adverse events, the difference was not statistically significant (risk ratio 3.29, 0.42 to 25.72). No conclusions could be drawn about other outcomes because of lack of evidence. Results should be interpreted cautiously given the low strength of evidence for most outcomes. The scope of this review was limited to trials that enrolled adult patients with major depressive disorder and compared a second generation antidepressant with CBT, and many of the included trials had methodological shortcomings that may limit confidence in some of the findings.What this study adds Second generation antidepressants and CBT have evidence bases of benefits and harms in major depressive disorder. Available evidence suggests no difference in treatment effects of second generation antidepressants and CBT, either alone or in combination, although small numbers may preclude detection of small but clinically meaningful differences.Funding, competing interests, data sharing This project was funded under contract from the Agency for Healthcare Research and Quality by the RTI-UNC Evidence-based Practice Center. Detailed methods and additional information are available in the full report, available at http://effectivehealthcare.ahrq.gov/

Polycyclic aromatic hydrocarbons as skin carcinogens: Comparison of benzo[a]pyrene, dibenzo[def,p]chrysene and three environmental mixtures in the FVB/N mouse

The polycyclic aromatic hydrocarbon (PAH), benzo[a]pyrene (BaP), was compared to dibenzo[def,p]chrysene (DBC) and combinations of three environmental PAH mixtures (coal tar, diesel particulate and cigarette smoke condensate) using a two stage, FVB/N mouse skin tumor model. DBC (4 nmol) was most potent, reaching 100% tumor incidence with a shorter latency to tumor formation, less than 20 weeks of 12-O-tetradecanoylphorbol-13-acetate (TPA) promotion compared to all other treatments. Multiplicity was 4 times greater than BaP (400 nmol). Both PAHs produced primarily papillomas followed by squamous cell carcinoma and carcinoma in situ. Diesel particulate extract (1 mg SRM 1650b; mix 1) did not differ from toluene controls and failed to elicit a carcinogenic response. Addition of coal tar extract (1 mg SRM 1597a; mix 2) produced a response similar to BaP. Further addition of 2 mg of cigarette smoke condensate (mix 3) did not alter the response with mix 2. PAH-DNA adducts measured in epidermis 12 h post initiation and analyzed by ³²P post‐labeling, did not correlate with tumor incidence. PAH‐dependent alteration in transcriptome of skin 12 h post initiation was assessed by microarray. Principal component analysis (sum of all treatments) of the 922 significantly altered genes (p < 0.05), showed DBC and BaP to cluster distinct from PAH mixtures and each other. BaP and mixtures up-regulated phase 1 and phase 2 metabolizing enzymes while DBC did not. The carcinogenicity with DBC and two of the mixtures was much greater than would be predicted based on published Relative Potency Factors (RPFs).Keywords: PAHs, Relative potency factor, Adducts, Cyp1b1, Cyp1a1, Ski

Viral testing of 10 cases of Theiler's disease and 37 in-contact horses in the absence of equine biologic product administration: A prospective study (2014-2018)

Background A novel equine parvovirus (EqPV-H) was recently discovered in the equine liver with Theiler's disease. Objectives To determine the prevalence of EqPV-H infection in naturally occurring Theiler's disease cases and in-contact horses in the absence of historical equine biologic product administration. Animals Ten cases of Theiler's disease from 6 separate properties were included in the study, based on the criteria of acute onset of clinical signs of liver failure with laboratory or histopathologic findings characteristic of Theiler's disease and no history of receiving an equine biologic product within the preceding 4 months. In addition, 37 in-contact horses from 4 of the 6 properties were screened for EqPV-H infection and hepatitis. Methods In prospective case series, cases were diagnosed with Theiler's disease by the attending veterinarian and were tested for EqPV-H by PCR of liver or serum. In-contact horses were assessed via serum chemistry and PCR at the attending veterinarian's discretion. Hepatitis was defined as serum gamma-glutamyltransferase activity above reference interval. The association of EqPV-H with hepatitis was determined by Fisher's exact test. Results Nine of 10 (90%) Theiler's disease cases and 54% of tested in-contact horses were EqPV-H positive. Hepatitis was significantly associated with EqPV-H infection (P = .036). Conclusions and Clinical Importance Although further study is required to identify EqPV-H as the causative agent of Theiler's disease, EqPV-H appears strongly associated with cases of fatal Theiler's disease and subclinical hepatitis in horses in contact with those cases. The prevalence of EqPV-H infection on affected properties can be high

Effects of Polychlorinated Dibenzo-p-Dioxins, Polychlorinated Dibenzofurans, and Polychlorinated Biphenyls in Human Liver Cell Models (in vitro) and in Mice (in vivo)

Polychlorinated dibenzo-p-dioxins, dibenzofurans, and polychlorinated biphenyls are persistent environmental pollutants which ubiquitously occur as complex mixtures and accumulate in the food and feed chain due to their high lipophilic properties. Of the 419 possible congeners, only 29 share a common mechanism of action and cause similar effects, the so called dioxin-like compounds. Dioxin-like compounds evoke a broad spectrum of biochemical and toxic responses, i.e. enzyme induction, dermal toxicity, hepatotoxicity, immunotoxicity, carcinogenicity as well as adverse effects on reproduction, development, and the endocrine system in laboratory animals and in humans. Most, if not all, of the aforementioned responses, are mediated by the aryl hydrocarbon receptor. In the present work, the elicited biochemical effects of a selection of dioxin-like compounds and the non dioxin-like PCB 153 were examined in mouse (in vivo) and in human liver cell models (in vitro). Emphasis was given to the main contributors to the total toxic equivalents in human blood and tissues TCDD, 1-PnCDD, 4-PnCDF, PCB 118, PCB 126, and PCB 156, which likewise contribute about 90 % to the dioxin-like activity in the human food chain. Three mouse in vivo studies were carried out aiming to characterize the alterations in hepatic gene expression as well as the induction of hepatic xenobiotic metabolizing enzymes after single oral dose. Based on the results obtained from mouse 3-day and 14-day studies, the seven test compounds can be categorized into three classes; the ones which are 'pure' AhR ligands (TCDD, 1-PnCDD, 4-PnCDF, and PCB 126) or solely CAR inducers (PCB 153), and the ones which are AhR/CAR mixed-type inducers (PCB 118, PCB 156). Moreover, the analysis of hepatic gene expression patterns after a single oral dose of either TCDD or PCB 153 revealed that the altered genes fundamentally differed. Profiling of significantly altered genes led to the conclusion that changes in gene expression were associated with different signalling pathways, in fact by AhR and CAR. For investigating the role of the AhR in mediating biological responses, several experimental approaches were carried out, such as the analysis of blood plasma metabolites in Ahr knockout and wild-type mice. Genotype specifics and similarities were determined by HPLC-MS/MS analysis. Several plasma metabolites could be identified in both genotypes, but also differences were detected. Furthermore, an in vivo experiment was performed aiming to characterize AhR-dependent and -independent effects in female Ahr knockout and wild-type mice. For this purpose, mice received a single oral dose of TCDD and were killed 96 h later. Microarray analysis of mouse livers revealed that although the Ahr gene was knocked out in Ahr-/- mice, the quantity of affected genes were in the same order of magnitude as for Ahr+/+ mice, but the pattern of altered genes distinctly differed. In addition, the relative liver weights of TCDD-treated Ahr+/+ mice were significantly increased which led to the conclusion, that TCDD induced the development of hepatic steatosis in female Ahr wild-type. The performed in vitro experiments aimed to characterize the effects elicited by selected DLCs and PCB 153 in human liver cell models by the use of HepG2 cells and primary human hepatocytes. In general, primary human hepatocytes were less responsive than HepG2 cells. This was not only observed in EC values derived from EROD assay, but also regarding microarray analysis in terms of differently regulated genes. In vitro REPs gained from both liver cell models widely confirmed the current TEFs, but some deviations occurred. The comparison of the TCDD-altered genes in both human cell types revealed that only a considerably small number of genes was in common up regulated by both human liver cell models, such as the established AhR-regulated highly inducible cytochrome P450s 1A1, 1A2, and 1B1 as well as other AhR target genes. Although the overlap was rather small, the TCDD-induced genes could be consistently associated with the broad spectrum of established dioxin-related biological responses. The gene expression pattern in primary human hepatocytes after treatment with selected DLCs (TCDD, 1-PnCDD, 4-PnCDF, and PCB 126) and PCB 153 was additionally characterized by microarray analysis. The highest response in terms of significantly altered genes was determined for TCDD, followed by 4-PnCDF, 1-PnCDD, and PCB 126, whereas exposure to PCB 153 did not evoke any significant changes in gene expression. The pattern of significantly altered genes was very homogenous among the four congeners. Genes associated with well-established DLC-related biological responses as well as novel dioxin-inducible target genes were identified, whereby an extensive overlap in terms of up regulated genes by all four DLCs occurred. In conclusion, the results from the in vitro experiments performed in primary human hepatocytes provided fundamental insight into the congeners' potencies and caused alterations in gene expression patterns. The obtained findings implicate that although the extent of enzyme inducibilities varied, the gene expression patterns are coincidental. Microarray analysis identified species-specific (mouse vs. human) as well as model-specific (in vitro vs. in vivo and transformed cells vs. untransformed cells) differences. In order to identify novel biomarkers for AhR activation due to treatment with dioxin-like compounds, five candidates were selected based on the microarray results i.e. ALDH3A1, TIPARP, HSD17B2, CD36, and AhRR. Eventually, ALDH3A1 turned out to be the most reliable and suitable marker for exposure to DLCs in both human liver cell models eliciting the highest mRNA inducibility among the five chosen candidates. In which way these species- and cell type-specific markers are involved in the dioxin-elicited toxic responses should be further characterized in vivo and in vitro.Polychlorierte Dibenzo-p-Dioxine, Dibenzofurane und polychlorierte Biphenyle sind persistente Umweltkontaminaten, welche als komplexe Gemische ubiquitär vorkommen und sich aufgrund ihrer lipophilen Eigenschaften in der Nahrungskette anreichern. Von den 419 möglichen Kongeneren teilt nur eine verhältnismäßig kleine Gruppe von 29 Verbindungen den gleichen Wirkmechanismus und das gleiche biologische Wirkspektrum, die sogenannten Dioxin-artigen Verbindungen. Dioxin-artige Verbindungen verursachen eine Vielzahl von biochemischen und toxischen Effekten, z. B. die Induktion von Enzymen, dermale Toxizität, Lebertoxizität, Immuntoxizität, und Kanzerogenität. Aber auch die Beeinträchtigung der Fortpflanzung, der normalen Entwicklung und des Hormonhaushalts konnten im Tiermodell und am Menschen beobachtet werden. Die meisten, wenn nicht sogar alle Wirkungen werden durch die Bindung der Dioxin-artigen Kongenere an den Arylhydrocarbon Rezeptor hervorgerufen. In der vorliegenden Arbeit, wurden die biochemischen Effekte durch Behandlung mit einer Auswahl Dioxin-artiger Verbindungen sowie von PCB 153, ein nicht Dioxin-artiges polychloriertes Biphenyl, im Mausmodell (in vivo) und in humanen Leberzellmodellen (in vitro) untersucht. Im Mittelpunkt standen sieben Kongenere, TCDD, 1-PnCDD, 4-PnCDF, PCB 118, PCB 126, PCB 153 und PCB 156, welche mit ca. 90 % den größten Anteil zur gesamten Dioxin-Aktivität in der Nahrungskette beisteuern. Im Vordergrund der in vivo Mausstudien stand die Untersuchung der Veränderungen in der Expression hepatischer Gene sowie die Überprüfung der möglichen Induktion hepatischer fremdstoffmetabolisierender Enzyme nach einmaliger oraler Gabe der Testsubstanzen. Die sieben getesteten Kongenere können aufgrund der erhaltenen Resultate aus den 3-Tage und 14-Tage Mausstudien in drei Klassen eingeteilt werden: „reine“ AhR Liganden (TCDD, 1-PnCDD, 4-PnCDF, PCB 126), CAR Induktoren (PCB 153) sowie diejenigen, die sowohl den AhR als auch CAR aktivieren können (PCB 118, PCB 156). Zusätzlich wurde der mögliche Einfluss auf die Expression hepatischer Gene nach einmaliger oraler Gabe von TCDD und PCB 153 mit Hilfe der Microarrays untersucht. Es konnte gezeigt werden, dass die Art und die Anzahl der beeinflussten Gene sich grundlegend unterscheiden und unterschiedlichen Signalwegen (AhR und CAR) zugeordnet werden konnten. Des Weiteren wurde die physiologische Rolle des AhR sowie dessen Einfluss auf die TCDD-induzierten Veränderungen des Genexpressionsmusters in der Mausleber näher untersucht. Durch die HPLC-MS/MS-gestützte Untersuchung des Blutplasmas von Ahr Wild-Typ und Knockout Mäusen konnten Genotyp-spezifische Besonderheiten und Gemeinsamkeiten bestimmt werden. Mit Hilfe der etablierten Analysemethode war es möglich einige Plasmametabolite in beiden Genotypen zu identifizieren, aber auch spezifische Unterschiede konnten nachgewiesen werden. Darüber hinaus, wurde eine in vivo Mausstudie durchgeführt, um AhR-abhängige und AhR-unabhängige Effekte zu charakterisieren. Ahr Knockout und Wild-Typ Mäusen wurde TCDD einmalig oral verabreicht und die Tiere nach 96-stündiger Exposition getötet. Die anschließende Microarrayanalyse der Mauslebern zeigte, dass obwohl das Ahr Gen in den Ahr Knockout Mäusen nicht exprimiert war die Anzahl der durch TCDD- Behandlung beeinflussten Gene in derselben Größenordnung lag als bei den Wild-Typ Mäusen, jedoch das Genexpressionsmuster in der Leber sich grundlegend unterschied. Die TCDD-induzierten Veränderungen auf hepatischer Genexpressionsebene von Ahr Wild-Typ Mäusen sowie das erhöhte relative Lebergewicht der Tiere ließen die Schlussfolgerung zu, dass TCDD im vorliegenden Fall zu Entwicklung einer Fettleber in Wild-Typ Mäusen geführt hat. In den in vitro Versuchen sollten die Auswirkungen einer Reihe Dioxin-artiger Verbindungen und PCB 153 in menschlichen Leberzellmodellen (HepG2 Zellen und primäre humane Hepatozyten) untersucht werden. Allgemein konnte gezeigt werden, dass primäre humane Hepatozyten weniger sensitiv auf die Behandlung mit den Testsubstanzen reagiert haben als die immortalisierte Leberkarzinomzelllinie HepG2. Das wurde nicht nur anhand der EC-Werte aus dem EROD Assay beobachtet, sondern auch anhand der Anzahl veränderter Gene, welche mittels Microarray analysiert wurden. Die in vitro REPs, abgeleitet aus den Versuchen in den Leberzellmodellen, bestätigten überwiegend die aktuellen TEFs, jedoch wurde in einigen Fällen Abweichungen beobachtet. Der Vergleich TCDD-induzierter Veränderungen auf Genexpressionsebene in beiden Leberzellmodellen zeigte, dass nur eine verhältnismäßig kleine Anzahl von Genen übereinstimmend hoch reguliert wurde u. a. die etablierten AhR-regulierten, hoch induzierbaren Cytochrom P450 1A1, 1A2, und 1B1 sowie weitere etablierte AhR Zielgene. Diese hoch regulierten Gene konnten mit den vielfältigen etablierten biologischen Wirkungen von Dioxinen in Verbindung gebracht werden. Weiterhin wurde die Veränderungen der Genexpression in primären humanen Hepatozyten nach Behandlung mit ausgewählten Kongeneren (TCDD, 1-PnCDD, 4-PnCDF und PCB 126) sowie PCB 153 untersucht. TCDD verursachte die größte Anzahl an Veränderungen auf Gen-expressionsebene, gefolgt von 4-PnCDF, 1-PnCDD und PCB 126, wohingegen die Behandlung mit PCB 153 keinen Einfluss auf die Genexpression zeigte. Ein Vergleich der durch die vier Kongenere hoch regulierten Gene lieferte ein homogenes Bild mit einer großen Anzahl übereinstimmend induzierter Gene, wobei sowohl Gene, welche mit den biologischen und toxischen Wirkungen von Dioxinen in Zusammenhang gebracht werden, als auch neue Dioxin-induzierbare Gene identifiziert werden konnten. Zusammenfassend konnte gezeigt werden, dass obwohl das Ausmaß der CYP1A1 Induzierbarkeit abhängig vom Leberspender interindividuell stark variierte, die Veränderungen auf Ebene der Genexpression eine enorme Übereinstimmung aufwiesen. Weiterhin konnten mittels Microarrayanalyse Spezies-Abhängigkeiten (Maus vs. Mensch), als auch Modell-Abhängigkeiten (in vitro vs. in vivo sowie transformierte Zellen vs. nicht-transformierte Zellen) nachgewiesen werden. Die Suche nach neuen Biomarkern für die Exposition gegenüber Dioxin-artigen Verbindungen bildete einen weiteren Schwerpunkt der vorliegenden Arbeit. Der Vergleich der Microarrays führte zu fünf Spezies- und Zelltyp-spezifischen potentiellen Biomarker-Kandidaten, ALDH3A1, TIPARP, HSD17B2, CD36 und AhRR. Von diesen, stellte sich ALDH3A1 als der am besten geeignete Marker gegenüber der Exposition mit Dioxin-artigen Verbindungen in beiden humanen Leberzellmodellen heraus, welcher die höchste mRNA Induzierbarkeit unter den ausgewählten Kandidaten besaß. Auf welche Weise diese spezifischen Marker möglicherweise zu den Dioxin-vermittelten toxischen Wirkungen beitragen, sollte anhand weiterer in vivo und in vitro Experimente untersucht werden

Effects of Polychlorinated Dibenzo-p-Dioxins, Polychlorinated Dibenzofurans, and Polychlorinated Biphenyls in Human Liver Cell Models (in vitro) and in Mice (in vivo)

Polychlorinated dibenzo-p-dioxins, dibenzofurans, and polychlorinated biphenyls are persistent environmental pollutants which ubiquitously occur as complex mixtures and accumulate in the food and feed chain due to their high lipophilic properties. Of the 419 possible congeners, only 29 share a common mechanism of action and cause similar effects, the so called dioxin-like compounds. Dioxin-like compounds evoke a broad spectrum of biochemical and toxic responses, i.e. enzyme induction, dermal toxicity, hepatotoxicity, immunotoxicity, carcinogenicity as well as adverse effects on reproduction, development, and the endocrine system in laboratory animals and in humans. Most, if not all, of the aforementioned responses, are mediated by the aryl hydrocarbon receptor. In the present work, the elicited biochemical effects of a selection of dioxin-like compounds and the non dioxin-like PCB 153 were examined in mouse (in vivo) and in human liver cell models (in vitro). Emphasis was given to the main contributors to the total toxic equivalents in human blood and tissues TCDD, 1-PnCDD, 4-PnCDF, PCB 118, PCB 126, and PCB 156, which likewise contribute about 90 % to the dioxin-like activity in the human food chain. Three mouse in vivo studies were carried out aiming to characterize the alterations in hepatic gene expression as well as the induction of hepatic xenobiotic metabolizing enzymes after single oral dose. Based on the results obtained from mouse 3-day and 14-day studies, the seven test compounds can be categorized into three classes; the ones which are 'pure' AhR ligands (TCDD, 1-PnCDD, 4-PnCDF, and PCB 126) or solely CAR inducers (PCB 153), and the ones which are AhR/CAR mixed-type inducers (PCB 118, PCB 156). Moreover, the analysis of hepatic gene expression patterns after a single oral dose of either TCDD or PCB 153 revealed that the altered genes fundamentally differed. Profiling of significantly altered genes led to the conclusion that changes in gene expression were associated with different signalling pathways, in fact by AhR and CAR. For investigating the role of the AhR in mediating biological responses, several experimental approaches were carried out, such as the analysis of blood plasma metabolites in Ahr knockout and wild-type mice. Genotype specifics and similarities were determined by HPLC-MS/MS analysis. Several plasma metabolites could be identified in both genotypes, but also differences were detected. Furthermore, an in vivo experiment was performed aiming to characterize AhR-dependent and -independent effects in female Ahr knockout and wild-type mice. For this purpose, mice received a single oral dose of TCDD and were killed 96 h later. Microarray analysis of mouse livers revealed that although the Ahr gene was knocked out in Ahr-/- mice, the quantity of affected genes were in the same order of magnitude as for Ahr+/+ mice, but the pattern of altered genes distinctly differed. In addition, the relative liver weights of TCDD-treated Ahr+/+ mice were significantly increased which led to the conclusion, that TCDD induced the development of hepatic steatosis in female Ahr wild-type. The performed in vitro experiments aimed to characterize the effects elicited by selected DLCs and PCB 153 in human liver cell models by the use of HepG2 cells and primary human hepatocytes. In general, primary human hepatocytes were less responsive than HepG2 cells. This was not only observed in EC values derived from EROD assay, but also regarding microarray analysis in terms of differently regulated genes. In vitro REPs gained from both liver cell models widely confirmed the current TEFs, but some deviations occurred. The comparison of the TCDD-altered genes in both human cell types revealed that only a considerably small number of genes was in common up regulated by both human liver cell models, such as the established AhR-regulated highly inducible cytochrome P450s 1A1, 1A2, and 1B1 as well as other AhR target genes. Although the overlap was rather small, the TCDD-induced genes could be consistently associated with the broad spectrum of established dioxin-related biological responses. The gene expression pattern in primary human hepatocytes after treatment with selected DLCs (TCDD, 1-PnCDD, 4-PnCDF, and PCB 126) and PCB 153 was additionally characterized by microarray analysis. The highest response in terms of significantly altered genes was determined for TCDD, followed by 4-PnCDF, 1-PnCDD, and PCB 126, whereas exposure to PCB 153 did not evoke any significant changes in gene expression. The pattern of significantly altered genes was very homogenous among the four congeners. Genes associated with well-established DLC-related biological responses as well as novel dioxin-inducible target genes were identified, whereby an extensive overlap in terms of up regulated genes by all four DLCs occurred. In conclusion, the results from the in vitro experiments performed in primary human hepatocytes provided fundamental insight into the congeners' potencies and caused alterations in gene expression patterns. The obtained findings implicate that although the extent of enzyme inducibilities varied, the gene expression patterns are coincidental. Microarray analysis identified species-specific (mouse vs. human) as well as model-specific (in vitro vs. in vivo and transformed cells vs. untransformed cells) differences. In order to identify novel biomarkers for AhR activation due to treatment with dioxin-like compounds, five candidates were selected based on the microarray results i.e. ALDH3A1, TIPARP, HSD17B2, CD36, and AhRR. Eventually, ALDH3A1 turned out to be the most reliable and suitable marker for exposure to DLCs in both human liver cell models eliciting the highest mRNA inducibility among the five chosen candidates. In which way these species- and cell type-specific markers are involved in the dioxin-elicited toxic responses should be further characterized in vivo and in vitro.Polychlorierte Dibenzo-p-Dioxine, Dibenzofurane und polychlorierte Biphenyle sind persistente Umweltkontaminaten, welche als komplexe Gemische ubiquitär vorkommen und sich aufgrund ihrer lipophilen Eigenschaften in der Nahrungskette anreichern. Von den 419 möglichen Kongeneren teilt nur eine verhältnismäßig kleine Gruppe von 29 Verbindungen den gleichen Wirkmechanismus und das gleiche biologische Wirkspektrum, die sogenannten Dioxin-artigen Verbindungen. Dioxin-artige Verbindungen verursachen eine Vielzahl von biochemischen und toxischen Effekten, z. B. die Induktion von Enzymen, dermale Toxizität, Lebertoxizität, Immuntoxizität, und Kanzerogenität. Aber auch die Beeinträchtigung der Fortpflanzung, der normalen Entwicklung und des Hormonhaushalts konnten im Tiermodell und am Menschen beobachtet werden. Die meisten, wenn nicht sogar alle Wirkungen werden durch die Bindung der Dioxin-artigen Kongenere an den Arylhydrocarbon Rezeptor hervorgerufen. In der vorliegenden Arbeit, wurden die biochemischen Effekte durch Behandlung mit einer Auswahl Dioxin-artiger Verbindungen sowie von PCB 153, ein nicht Dioxin-artiges polychloriertes Biphenyl, im Mausmodell (in vivo) und in humanen Leberzellmodellen (in vitro) untersucht. Im Mittelpunkt standen sieben Kongenere, TCDD, 1-PnCDD, 4-PnCDF, PCB 118, PCB 126, PCB 153 und PCB 156, welche mit ca. 90 % den größten Anteil zur gesamten Dioxin-Aktivität in der Nahrungskette beisteuern. Im Vordergrund der in vivo Mausstudien stand die Untersuchung der Veränderungen in der Expression hepatischer Gene sowie die Überprüfung der möglichen Induktion hepatischer fremdstoffmetabolisierender Enzyme nach einmaliger oraler Gabe der Testsubstanzen. Die sieben getesteten Kongenere können aufgrund der erhaltenen Resultate aus den 3-Tage und 14-Tage Mausstudien in drei Klassen eingeteilt werden: „reine“ AhR Liganden (TCDD, 1-PnCDD, 4-PnCDF, PCB 126), CAR Induktoren (PCB 153) sowie diejenigen, die sowohl den AhR als auch CAR aktivieren können (PCB 118, PCB 156). Zusätzlich wurde der mögliche Einfluss auf die Expression hepatischer Gene nach einmaliger oraler Gabe von TCDD und PCB 153 mit Hilfe der Microarrays untersucht. Es konnte gezeigt werden, dass die Art und die Anzahl der beeinflussten Gene sich grundlegend unterscheiden und unterschiedlichen Signalwegen (AhR und CAR) zugeordnet werden konnten. Des Weiteren wurde die physiologische Rolle des AhR sowie dessen Einfluss auf die TCDD-induzierten Veränderungen des Genexpressionsmusters in der Mausleber näher untersucht. Durch die HPLC-MS/MS-gestützte Untersuchung des Blutplasmas von Ahr Wild-Typ und Knockout Mäusen konnten Genotyp-spezifische Besonderheiten und Gemeinsamkeiten bestimmt werden. Mit Hilfe der etablierten Analysemethode war es möglich einige Plasmametabolite in beiden Genotypen zu identifizieren, aber auch spezifische Unterschiede konnten nachgewiesen werden. Darüber hinaus, wurde eine in vivo Mausstudie durchgeführt, um AhR-abhängige und AhR-unabhängige Effekte zu charakterisieren. Ahr Knockout und Wild-Typ Mäusen wurde TCDD einmalig oral verabreicht und die Tiere nach 96-stündiger Exposition getötet. Die anschließende Microarrayanalyse der Mauslebern zeigte, dass obwohl das Ahr Gen in den Ahr Knockout Mäusen nicht exprimiert war die Anzahl der durch TCDD- Behandlung beeinflussten Gene in derselben Größenordnung lag als bei den Wild-Typ Mäusen, jedoch das Genexpressionsmuster in der Leber sich grundlegend unterschied. Die TCDD-induzierten Veränderungen auf hepatischer Genexpressionsebene von Ahr Wild-Typ Mäusen sowie das erhöhte relative Lebergewicht der Tiere ließen die Schlussfolgerung zu, dass TCDD im vorliegenden Fall zu Entwicklung einer Fettleber in Wild-Typ Mäusen geführt hat. In den in vitro Versuchen sollten die Auswirkungen einer Reihe Dioxin-artiger Verbindungen und PCB 153 in menschlichen Leberzellmodellen (HepG2 Zellen und primäre humane Hepatozyten) untersucht werden. Allgemein konnte gezeigt werden, dass primäre humane Hepatozyten weniger sensitiv auf die Behandlung mit den Testsubstanzen reagiert haben als die immortalisierte Leberkarzinomzelllinie HepG2. Das wurde nicht nur anhand der EC-Werte aus dem EROD Assay beobachtet, sondern auch anhand der Anzahl veränderter Gene, welche mittels Microarray analysiert wurden. Die in vitro REPs, abgeleitet aus den Versuchen in den Leberzellmodellen, bestätigten überwiegend die aktuellen TEFs, jedoch wurde in einigen Fällen Abweichungen beobachtet. Der Vergleich TCDD-induzierter Veränderungen auf Genexpressionsebene in beiden Leberzellmodellen zeigte, dass nur eine verhältnismäßig kleine Anzahl von Genen übereinstimmend hoch reguliert wurde u. a. die etablierten AhR-regulierten, hoch induzierbaren Cytochrom P450 1A1, 1A2, und 1B1 sowie weitere etablierte AhR Zielgene. Diese hoch regulierten Gene konnten mit den vielfältigen etablierten biologischen Wirkungen von Dioxinen in Verbindung gebracht werden. Weiterhin wurde die Veränderungen der Genexpression in primären humanen Hepatozyten nach Behandlung mit ausgewählten Kongeneren (TCDD, 1-PnCDD, 4-PnCDF und PCB 126) sowie PCB 153 untersucht. TCDD verursachte die größte Anzahl an Veränderungen auf Gen-expressionsebene, gefolgt von 4-PnCDF, 1-PnCDD und PCB 126, wohingegen die Behandlung mit PCB 153 keinen Einfluss auf die Genexpression zeigte. Ein Vergleich der durch die vier Kongenere hoch regulierten Gene lieferte ein homogenes Bild mit einer großen Anzahl übereinstimmend induzierter Gene, wobei sowohl Gene, welche mit den biologischen und toxischen Wirkungen von Dioxinen in Zusammenhang gebracht werden, als auch neue Dioxin-induzierbare Gene identifiziert werden konnten. Zusammenfassend konnte gezeigt werden, dass obwohl das Ausmaß der CYP1A1 Induzierbarkeit abhängig vom Leberspender interindividuell stark variierte, die Veränderungen auf Ebene der Genexpression eine enorme Übereinstimmung aufwiesen. Weiterhin konnten mittels Microarrayanalyse Spezies-Abhängigkeiten (Maus vs. Mensch), als auch Modell-Abhängigkeiten (in vitro vs. in vivo sowie transformierte Zellen vs. nicht-transformierte Zellen) nachgewiesen werden. Die Suche nach neuen Biomarkern für die Exposition gegenüber Dioxin-artigen Verbindungen bildete einen weiteren Schwerpunkt der vorliegenden Arbeit. Der Vergleich der Microarrays führte zu fünf Spezies- und Zelltyp-spezifischen potentiellen Biomarker-Kandidaten, ALDH3A1, TIPARP, HSD17B2, CD36 und AhRR. Von diesen, stellte sich ALDH3A1 als der am besten geeignete Marker gegenüber der Exposition mit Dioxin-artigen Verbindungen in beiden humanen Leberzellmodellen heraus, welcher die höchste mRNA Induzierbarkeit unter den ausgewählten Kandidaten besaß. Auf welche Weise diese spezifischen Marker möglicherweise zu den Dioxin-vermittelten toxischen Wirkungen beitragen, sollte anhand weiterer in vivo und in vitro Experimente untersucht werden

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Between the years of 2006 and 2011, 183 marine mammal strandings were recorded and analyzed by the Veterinary Diagnostics Laboratory at Oregon State University. Most of the strandings were of pinnipeds and porpoises. The species represented were California sea lion (69 animals), Steller sea lion (18 animals), harbor seal (42 animals), northern elephant seal (11 animals), northern fur seal (3 animals), Guadalupe fur seal (2 animals), harbor porpoise (27 animals), Dall’s porpoise (1 animal), northern right whale dolphin (1 animal), common dolphin (2 animals), grey whale (2 animals), sperm whale (2 animals), minke whale (1 animal), and Cuvier’s beaked whale (2 animals). Most of the stranding events were of adults and sub-adults with fewer cases of neonates and yearlings. Necropsies were performed on 48 of the stranded animals at Oregon State University by Veterinary Pathologists, and 135 were on site by biologists. Most of the necropsies performed in the diagnostic laboratories were of pinnipeds while the on-site necropsies included the majority of the cetacean strandings. There was clear seasonality in the stranding events with most occurrences in the summer months (June-August) with a late spike of strandings in October. Important zoonotic diseases were confirmed in several of the stranded species. Leptospirosis was confirmed in 34 pinnipeds (California Sea Lion, Stellar Sea Lion, and Harbor Seal) with the majority of the deaths occurring in the years of 2009 and 2010. Encephalitis was found in 11 pinnipeds, 8 of which were seals with meningoencephalitis. Cryptococcosis, a disease known to afflict porpoises in British Columbia, was found in 4 porpoises (harbor porpoises and Dall’s Porpoise). Other notable causes of death were domoic acid toxicity, Clostridium infection, and Streptococcus infection. Other putative causes of mortality were toxoplasmosis in seals, and Otariid herpesvirus in Sea Lions. The high frequency of zoonotic disease found in animals off the Oregon Coast underscore the necessity for public education regarding the dangers of contact with stranded marine mammals.Keywords: Oregon Coast, Marine Mammal StrandingsKeywords: Oregon Coast, Marine Mammal Stranding