Thyroid growth and function is partly regulated by growth factors binding to receptors on the cell surface. In the present thesis, the transforming growth factor-β (TGF-β) superfamily members have been studied for their role in regulation of growth and differentiation of both normal and neoplastic thyroid epithelial cells. TGF-β1 is a negative regulator of thyrocyte growth and function. However, the importance of other TGF-β superfamily members has not been fully investigated. TGF-β1, activin A, bone morphogenetic protein (BMP)-7 and their receptors were found to be expressed in porcine thyrocytes. In addition to TGF-β1, activin A was also found to be a negative regulator of thyroid growth and function, and both stimulated phosphorylation and nuclear translocation of Smad proteins. Furthermore, TGF-β1 and epidermal growth factor (EGF) demonstrated a synergistic negative effect on thyrocyte differentiation. Simultaneous addition of the two factors resulted in a loss of the transepithelial resistance and expression of the epithelial marker E-cadherin. This was followed by a transient expression of N-cadherin. Despite the extremely malignant character of anaplastic thyroid carcinoma (ATC) tumor cells, established cell lines are still responsive to TGF-β1. A majority of the cell lines were also found to be growth inhibited by BMP-7. BMP-7 induced cell cycle arrest of the ATC cell line HTh 74 in a dose- and cell density-dependent manner. This was associated with upregulation of p21CIP1 and p27KIP1, decreased cyclin-dependent kinase (Cdk) activity and hypophosphorylation of the retinoblastoma protein (pRb). TGF-β1, and to some extent also BMP-7, induced the expression of N-cadherin and matrix metalloproteinase (MMP)-2 and -9. Stimulation of HTh 74 cells with TGF-β1 increased the migration through a reconstituted basement membrane indicating an increased invasive phenotype of the cells. Taken together, these data show that TGF-β superfamily members not only affect growth and function of normal thyroid follicle cells but may also, in combination with EGF, play a role in cell dedifferentiation. This study additionally suggests that the TGF-β superfamily members may be important for the invasive properties of ATC cells.

<p>Cancer or malignant tumors has a high death frequency in many countries. Nowadays many research facilities are dedicated to find new substances and techniques which would lead to better cancer therapies. Seven years ago a research team from Finland made a remarkable connection between vitamin D deficiencies and an increased chance of getting prostate cancer. The research investigating this statement has lead to findings of a new non-classical effect of the calcium controlling vitamin, 1,25(OH)2D3. This effect involves anti-proliferatory effects and more importantly apoptotic effects resulting in the hope of finding a new drug that can cure prostate cancer with the smallest amount of harm to the body.</p><p>In an attempt to find out if the signalling pathway of this apoptotic effect is fast or slow, an experiment designed to detect when the apoptotic protein caspase-3 is induced has been performed. Cells from the cell line LNCaP has been cultured and incubated with 1,25(OH)2D3 and after 0min - 48h an assay was performed to detect the relative amounts of caspase-3 present in every sample. The optimal time period (48h) was then subjected to three different concentrations of 1,25(OH)2D3 and read in the same way as the previous samples. The results showed an increase in caspase-3 expression as early as 2 min, but disappear to be seen again at 24h and are more profound in 48h samples. The caspase-3 expression was also seen to form a possible exponential curve in dose-response.</p>

Made available in DSpace on 2016-03-04T13:55:10Z (GMT). No. of bitstreams: 2 3.pdf: 1209769 bytes, checksum: 5ca426f3d62b4023c66df6040fc8d22e (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2015 / Fundação Oswaldo Cruz. Instituto de Tecnologia em Fármacos/Farmanguinhos. Rio de Janeiro, RJ, Brasil. / Atualmente é notório o crescimento da Gestão da Qualidade e, com esta, desenvolvem-se também as Boas Práticas de Fabricação e Controle, que são ferramentas que auxiliam na obtenção de produtos de qualidade. Ao falar de qualidade na indústria farmacêutica, fala-se, sobretudo da qualidade físico-química e microbiológica tanto das matérias-primas empregadas na fabricação como do produto terminado obtido após as diversas etapas produtivas. Com objetivo de alcançar esta qualidade este projeto buscou verificar as metodologias empregadas no dia a dia da Divisão de Controle de Especificação do Laboratório Farmacêutico da Marinha (LFM). As técnicas empregadas no controle microbiológico, em sua maioria, são as mesmas, consistindo na realização do ensaio limite (contagem de micro-organismos) e na pesquisa e identificação de patógenos. No entanto deve-se verificar se o produto analisado não afeta o crescimento microbiano, inibindo-o e fazendo com que se tenha resultados falso-negativos, o que acarretaria em desvios da qualidade podendo levar a danos para a saúde do usuário e prejuízos para a imagem da Instituição. Elegeram-se as seguintes formulações, todas de uso oral, para serem avaliadas: aciclovir 200 mg comprimidos, isoniazida 100 mg comprimidos, pirazinamida 500 mg comprimidos, ofloxacino 400 mg comprimidos, pirazinamida suspensão 3%, bromexina xarope, prednisona 5 mg comprimidos e complexo vitamínico e minerais comprimidos. Estas formulações foram avaliadas frente às cepas de referência, conforme procedimentos preconizados pela Farmacopeia Brasileira 5ª Ed. Durante o ensaio verificou-se que todas as formulações, exceto o aciclovir e a pirazinamida suspensão, inibiram o crescimento das cepas testadas. Foram testados métodos de neutralização da atividade inibitória do crescimento microbiano, tendo sido selecionados os seguintes procedimentos: diluição para as formulações de isoniazida 100 mg, prednisona 5 mg e complexo vitamínico, uso de neutralizante, polissorbato 80, para bromexina xarope e filtração por membrana para pirazinamida 500 mg comprimidos, logrando-se êxito para o ensaio do limite. Somente para o ofloxacino não foi possível recuperar os micro-organismos e no caso da pirazinamida comprimidos, a mesma não foi susceptível à pesquisa de Escherichia coli, nas condições preconizadas pela Farmacopeia Brasileira 5ª Ed. O presente trabalho identificou que das oito formulações testadas, seis inibem o crescimento microbiano e, portanto interferem na análise. Após adequações, os métodos responderam aos testes e foram desta forma considerados validados, podendo ser utilizados de forma segura na rotina do laboratório. / Nowadays it is remarkable the development of the Quality Management, together with it the Good Manufacturing Practices and Control, which are tools that help to afford products with high quality. Concerning to quality issues in the Pharmaceutical Industry, the main objective is to achieve high physical-chemical and microbiological quality of the raw materials used for manufacturing, as well of the final product after the several processing steps. Aiming to succeed in attaining this quality parameter, this project has attempted to verify the methodologies daily employed by the Specification Control Division of Brazilian Navy Pharmacautical Laboratory (LFM). The techniques employed for the microbiological quality control are usually the same, and consist of performing the limit assay (microorganism counting) and the search and identification of pathogens. Nevertheless, it must be checked if the product under analysis does not affect the microbial growth, causing an inhibition and leading to false-negative results, which might drive to quality deviance, ultimately harming the final user and bringing damage to the institution image. In this project, the following oral formulations have been selected to be evaluated: aciclovir 200 mg tablets, isoniazid 100 mg tablets, pyrazinamide 500mg tablets, ofloxacin 400 mg tablets, pyrazinamide 3% suspension, bromexine syrup, prednisone 5 mg tablets and tablets containing vitamin complex and minerals. These formulations have been evaluated against the growth of reference strains, in accordance to the procedures described in the Brazilian Pharmacopeia 5th Edition. During the assay, it has been found all formulations, exemption given to aciclovir and pyrazinamide suspension, inhibited the growth of the assayed strains. Methods for neutralizing the microbial growth inhibition activity have been assessed and the selected procedures were: diluition for isoniazid 100mg, prednisone 5 mg and vitamin complex; use of the neutralizer polysorbate 80 for bromexine syrup; and membrane filtration for pyrazinamide 500 mg tablets, which allowed the recovery of all microorganisms. Only for ofloxacin it was not possible to recover the microorganisms and for pyrazinamide tablets, the formulation was not susceptible to the Escherichia coli assay, pursuant to the Brazilian Pharmacopeia 5th Edition. The present study has identified that six out of the eight assayed formulations have inhibited microbial growth, therefore interfering in the analysis outcome . After adjustments, the methods have trustworthy worked and were thus considered validated, and now can be applied safely in the laboratory's routine.

Biologiska toxicitetstester utförs genom att exponera en testorganism för olika koncentrationer av kemikalier under en bestämd period. Det finns akuta toxicitetstester och kroniska. Resultat från akuta studier presenteras som EC50-värde (Effect Concentration, affecting 50 % of the population). Tester som används som underlag för riskbedömningar ska utföras på kvalitetsmässigt acceptabelt sätt som grundas på International Organization for Standardization (ISO) och Good Labaratory Practice (GLP). Syftet med studien var att studera toxisk inverkan av kaliumdikromat på encellig sötvattenalg, R. subcapitata, genom att räkna cellantal med två olika instrument: flödescytometer och automatisk cellräknare. Vidare att jämföra testernas EC50 medelvärde mot ISO 8692 angivet värde i precisions syfte och att utvärdera de båda räknemetoderna gällande precision och analystid. Kaliumdikromat användes för tillväxtinhibering vid toxicitetstest. EC50-resultaten visade ingen statistiskt signifikant skillnad mellan de båda instrumenten (p=0,47). Den akuta toxicitetsanalysens precision kunde bekräftas som giltig då båda mätmetoders EC50 medelvärden vid jämförelse med ISO 8692 värde befanns inom bestämda 95% konfidensintervallet. Vid jämförelse av studiens två mätningsmetoder, observerades större spridning kring medelvärdet i cellräknarens resultat, där tre EC50 värden hamnade utanför 95% CI. Däremot visade resultatet från flödescytometern mindre spridning och högre noggrannhet jämfört med cellräknarens. Studien visade att flödescytometer skulle kunna användas i framtida toxikologiska tester med encelliga alger, men det krävs flera upprepade försök för att bekräfta fördelar med analysen i flödescytometern. / Biological toxicity tests are performed by exposing a test organism to different concentrations of chemicals over a certain period of time. Results from acute studies are presented as EC50 (Effect Concentration, affecting 50% of the population). Tests used as a basis for risk assessments shall be performed in a quality acceptable way based on the International Organization for Standardization (ISO) and Good Laboratory Practice (GLP). The aim of this study was to study the toxic effect of potassium dichromate on unicellular green algae R. subcapitata, by counting cells with two different apparatus: flow cytometer and automatic cell counter. Additionally, to compare the EC50 mean values against the ISO 8692 value for control of test precision and to compare accuracy and analytical time of two methods. Potassium dichromate was used for growth inhibition in toxicity tests. The EC50 results showed no statistically significant difference between the two instruments (p = 0.47). The accuracy of acute toxicity analysis was confirmed as valid as both EC50 average measurement values compared to ISO 8692 value were found within the 95% confidence interval. When comparing the two methods of the study, greater spread was observed around the mean value in the cell count's results, where three EC50 values were outside 95% CI. The result of the flow cytometer had less spread and higher accuracy compared to the cell count. The study showed that flow cytometers could be used in future toxicological tests with algae, but several repeated tests are required to confirm the benefits of analysis with the flow cytometer.

Realizou-se a pesquisa de anticorpos aglutinantes (AcA) anti-leptospira, através da técnica de soroaglutinação microscópica (SAM) e tentativas de isolamento do agente etiológico em 29 cães com suspeita clínica de leptospirose. Foi também realizada a pesquisa de material genético de Leptospira spp., utilizando-se a técnica de reação em cadeia de polimerase (PCR) em 24 amostras de urina dos mesmos cães. Com o objetivo de determinar a proteção cruzada entre os sorovares icterohaemorrhagiae e copenhageni, 24 cães adultos foram avaliados antes e após a vacinação com uma dose de vacina contendo os antígenos icterohaemorrhagiae, canicola, grippotyphosa e pomona, utilizando-se o teste de inibição de crescimento in vitro (TIC) dos sorovares canicola, copenhageni e icterohaemorrhagiae. Os títulos de AcA anti-copenhageni foram os mais freqüentemente observados nos cães com suspeita clínica de leptospirose, havendo entretanto, reação cruzada entre diferentes sorovares. Foram isoladas quatro amostras de leptospira, das quais três foram caracterizadas por anticorpos policlonais e por Variable Number Tandem Repeat (VNTR) como sorovar canicola. A quarta amostra isolada reagiu em alto título com o anti-soro policlonal anti-sorovar copenhageni (51.200), não tendo sido testado com o anti-soro anti-icterohaemorrhagiae. Pela técnica de VNTR, essa amostra foi classificada como pertencente ao sorogrupo icterohaemorrhagiae e, finalmente, pelo uso dos anticorpos monoclonais F70 C24, F70 C14-10, F12 C3-11 e F89 C12, para a diferenciação dos representantes do sorogrupo icterohaemorrhagiae, essa amostra isolada apresentou o comportamento imunológico do sorovar copenhageni (cepa padrão L1 130, FIOCRUZ - Bahia). Considerando-se como critério sorológico de confirmação do diagnóstico clínico de leptospirose, títulos maiores ou iguais a 800 em amostra única de soro, ou o aumento ou declínio de quatro vezes os títulos de AcA (duas diluições) em duas amostras pareadas de soro, houve a confirmação do diagnóstico etiológico em 9 de 24 cães (37,5%) pela SAM. Por outro lado, 11 das 24 amostras de urina (45,8%) foram positivas à PCR. A associação das duas técnicas permitiu a confirmação diagnóstica em 15 cães (62,5%). Os títulos de anticorpos neutralizantes (AcN) (TL50) pré-vacinais contra os sorovares icterohaemorrhagiae, canicola e copenhageni foram respectivamente de 1,444±0,278, 0,725±0,317 e 0,583±0,322, e os títulos pós-vacinais foram respectivamente de 1,455±0,287, 1,475±0,270 e 0,510±0,304. Considerando-se o título de AcN maior ou igual a 1 como título protetor contra a infecção leptospírica, no momento pré-vacinal, os cães ainda apresentavam AcN contra o sorovar icterohaemorrhagiae capazes de protegê-los contra a infecção natural, não tendo havido também uma resposta adicional ao estímulo vacinal. Com relação ao sorovar canicola, houve aumento significativo dos títulos de AcN após a imunização (p=0,001) quando comparado ao momento pré-vacinal, tendo sido desenvolvida uma resposta protetora. Embora os animais não tenham sido vacinados contra o sorovar copenhageni, a presença de AcN pré-vacinal e pós-vacinal pode ser justificada pela reatividade cruzada entre ambos, copenhageni e icterohaemorrhagiae, pertencentes ao mesmo sorogrupo; entretanto os títulos pré- e pós-vacinais não foram da mesma magnitude dos produzidos contra o sorovar icterohaemorrhagiae. Portanto, a vacina contendo bacterina do sorovar icterohaemorrhagiae não é capaz de eliciar resposta protetora contra o sorovar heterólogo copenhageni. / A research on agglutinating antibodies (AAc) anti-leptospira has been performed, through microscopic agglutination test (MAT) and attempts of isolation of the etiologic agent in 29 dogs with clinical suspicious of leptospirosis. There was also made a research of Leptospira spp.´s genetic material, using polimerase chain reaction (PCR) in 24 urine samples of the same dogs. With the aim to determine the cross protection between serovars icterohaemorrhagiae and copenhageni, 24 adult dogs were evaluated before and after vaccination with one dose of a vaccine containing icterohaemorrhagiae, canicola, grippotyphosa and pomona antigens, by the in vitro inhibition growth test (GIT) of serovars canicola, icterohaemorrhagiae and copenhageni. The AAc anti-copenhageni titers were the most frequently obseeved in the dogs with clinical suspicious of leptospirosis, existing however, cross reaction among different serovars. There were isolated four samplas of leptospira, of witch three were all characterizated by polyclonal antibodies and Variable Nunber Tandem Repeat (VNTR) as serovar canicola. The fourth isolated sample reacted in high titers to polyclonal antisera anti-copenhageno (51.200), but is was not tested with antisera anti-icterohaemorrhagiae. By VNTR technique, this sample was classified as belonging to the serogroup icterohaemorrhagiae, and finally by the use of monoclonal antibodies F70 C24, F70 C14-10, F12 C3-11 and F89 C12, for differentiation of the representatives of serogroup icterohaemorrhagiae. This isolated sample presented the immunological behavior of serovar copenhageni (standard strain LI 130, FIOCRUZ - Bahia). Considering the sorologic criteria confirmation of clinical diagnosis of leptospirosis, titers higher or equal than 800 in a unique serum sample, or the increase or decrease of four times of AAc titers (two dilutions) in two paired serum samples, there was the conformation of etiologic diagnosis in 9 of the 24 dogs (37,5%) by MAT. However, 11 out of 24 urine samples (45,8%) were positive at PCR. The association of both techniques allowed the diagnostic conformation in 15 dogs (62,5%). The prevaccinal neutralizing antibodies (NAc) titers (TL50) were respectively 1,444±0,278, 0,725±0,317 and 0,583±0,322. And the postvaccinal titers were respectively 1,455±0,287, 1,475±0,270 and 0,510±0,304. Considering the NAc titer higher than 1 as a protective titer against leptospiral infection, at prevaccinal moment the dogs still presented NAc against serovar icterohaemorrhagiae capable to protect them against natural infection, an adictional response to the vaccinal stimulus had not occurred. Concerning serovar canicola, there was a significant increase of NAc titers after immunization (p=0,001) when compared to prevaccinal moment, and a protective response was developed. Although the animals were not vacinated against serovar copenhageni, the presence of prevaccinal and postvaccinal NAc can be explained by cross reactivity between both, copenhageni and icterohaemorrhagiae, belonging to same serogroup; however, the pre- and postvaccinal titers were not of the same magnitude of those produced against serovar icterohaemorrhagiae. Therefore, the vaccine containing bacterins of serovar icterohaemorrhagiae is not capable of eliciting protective response against the heterologous serovar copenhageni.

Cancer or malignant tumors has a high death frequency in many countries. Nowadays many research facilities are dedicated to find new substances and techniques which would lead to better cancer therapies. Seven years ago a research team from Finland made a remarkable connection between vitamin D deficiencies and an increased chance of getting prostate cancer. The research investigating this statement has lead to findings of a new non-classical effect of the calcium controlling vitamin, 1,25(OH)2D3. This effect involves anti-proliferatory effects and more importantly apoptotic effects resulting in the hope of finding a new drug that can cure prostate cancer with the smallest amount of harm to the body. In an attempt to find out if the signalling pathway of this apoptotic effect is fast or slow, an experiment designed to detect when the apoptotic protein caspase-3 is induced has been performed. Cells from the cell line LNCaP has been cultured and incubated with 1,25(OH)2D3 and after 0min - 48h an assay was performed to detect the relative amounts of caspase-3 present in every sample. The optimal time period (48h) was then subjected to three different concentrations of 1,25(OH)2D3 and read in the same way as the previous samples. The results showed an increase in caspase-3 expression as early as 2 min, but disappear to be seen again at 24h and are more profound in 48h samples. The caspase-3 expression was also seen to form a possible exponential curve in dose-response.

Antifouling paints are applied on vessels to prevent growth of fouling organisms such hasbarnacles. Presently, there are a number of different paints available on the Swedish marketwith different strategies and active substances. The paints might work by either continuouslyreleasing biocides or physically by peeling off or provide an easily cleansed surface whereorganisms cannot attach. The physically working paints do not need to register an activesubstance since its purpose is not to affect living organisms by a chemical or biological modeof action. In this study, two commercially available paints, the copper-based Fabi 3959(International Paint Ltd) and physically eroding, biocide-free labelled Mille Light (HempelFärg AB) were compared to Hard Racing superior, containing copper and the forbiddensubstance Tributyltin. Fabi International is only allowed to be used on the Swedish west coastdue to 6% added as active substance while the biocide-free Mille Light is eligible for eastcoast usage. The toxic effect from respective paint was investigated by assembling a growthinhibition test with the red macro alga Ceramium tenuicorne. The results show that all thestudied paints had a negative effect on growth and therefore leaked substances inconcentrations high enough to be harmful to the alga. The toxic response differed with theeffect on growth being in the following order, Hard racing superior&gt;Fabi &gt;Mille Light.Implications regarding the current legalization involving biocide-free labelled antifoulingpaints are discussed.

The sterol biosynthetic pathway is essential for growth of all eukaryotic cells and the main target of antifungal agents. The emergence of resistance to these antifungals in an already ill patient population indicates a need to develop drugs that have a broad spectrum of activity among pathogenic fungi and have minimal patient toxicity. Squalene synthase is the first committed step in the sterol pathway and has been studied intensively for development of antifungal agents. While the overall architecture of this enzyme is identical throughout eukaryotes, it was shown that plant and animal genes cannot complement a squalene synthase knockout mutation in yeast unless the carboxy-terminal domain is swapped for one of fungal origin. This implies that there is a component of the fungal carboxy-terminal domain that is responsible for the complementation phenotype and that is unique to the fungal kingdom of life. To determine the role of the carboxy-terminal domain of squalene synthase in the sterol pathway, we used the yeast Saccharomyces cerevisiae with a squalene synthase knockout mutation and expressed squalene synthases originating from fungi, plants, and animals. In contrast to previous observations, all enzymes tested could partially complement the knockout mutation when the genes were weakly expressed. When induced, non-fungal squalene synthases could not complement the knockout mutation and instead led to the accumulation of carboxysterol intermediates, suggesting an interaction between squalene synthase and the downstream sterol C4-decarboxylase. Overexpression of a sterol C4-decarboxylase from any kingdom of life both decreased the accumulation of carboxysterol intermediates and allowed non-fungal squalene synthases to complement the squalene synthase knockout mutation. Using chimeric squalene synthases from each kingdom of life, the motif in the C-terminal domain responsible for preventing this toxicity was mapped to a kingdom-specific 26-amino acid hinge motif adjacent to the catalytic domain. Furthermore, over-expression of the carboxy-terminal domain alone containing a hinge motif from fungi, not from animals or plants, led to growth inhibition of wild-type yeast. Since this hinge region is unique to and highly conserved within each kingdom of life, this data provides evidence for the development of an antifungal therapeutic as well as for tools to develop an understanding of triterpene catalytic activity and identify similar motifs in other biosynthetic pathways.

The following contains two projects focused on the fungal pathogen, Fusarium oxysporum. The first project was purely computational in the examination of transposable elements (TEs), which are mobile sequences with the ability to multiply and move in their host genome. In F. oxysporum, TEs such as miniature impala elements are associated with the secreted in xylem gene that are related to its virulence over its host. The F. oxysporum species complex can be utilized as a model system for the examination of TE content and TE expression during the infection cycle. To find whether TEs play a role in the infection process and if their expression changes when fungi are in planta, a comparison was made using RNA-seq data from a pathogenic (Fo5176) and a non-pathogenic strain (Fo47) of F. oxysporum interacting with the model plant Arabidopsis thaliana. Complementary to this, the copy numbers of the same TEs were calculated in the two aforementioned strains and in F. oxysporum f.sp. lycopersici 4287 (Fo4287) to find if there was a correlation between expression and copy number. Using these two different datasets together showed that TE expression and copy number are lower in the non-pathogenic strain and unlinked in the infection course. The second project examined the growth inhibition of Fusarium oxysporum isolates Fo32931 (the isolate pathogenic to immunocompromised humans) and Fo4287 with the use of extracts from chilies of Capsicum chinense. Pepper plants were grown from seed and the peppers were harvested for an ethanol (100%) extraction. After preparation, the optical density of growth of the F. oxysporum isolates was measured for a 48-hour period with 96-well plate containing varying concentrations of the extracts and controls. Growth curves were analyzed and normalized to a growth control. After doing High Performance Liquid Chromatography, an estimated concentration of capsaicin (the causal agent of the burning sensation from hot chilis) was established. A correlation between the amount of growth inhibition and the concentration of capsaicin was made. Taken together, the data suggests that an increase of capsaicin concentration in extracts is correlated with reduced growth for the two tested isolates of F. oxysporum.

Das Peptid Endothelin-1 (ET-1) hat neben seiner vasokonstriktorischen Wirkung auch wachstumsinduzierende Eigenschaften. Um seine Bedeutung für Tumorwachstum zu untersuchen wurde das ET-System des experimentellen Lebertumors Morris-Hepatom (MH)-7777 in vitro und in vivo zunächst charakterisiert. Erstmals wurde dann versucht, Tumorwachstum auch in vivo durch Behandlung mit einem ET-Rezeptorantagonisten zu inhibieren. METHODEN: Im Kulturüberstand von MH-7777-Zellen wurde die Menge des synthetisierten irET-1 gemessen. Über Proliferationsassays erfolgte die Untersuchung des Zellwachstums bei Inkubation mit ET-1 sowie den ET-Rezeptorantagonisten BQ 123, LU 135252 und LU 302872. Zur Charakterisierung des ET-Systems im MH-7777 in vivo wurden ir(Big-)ET-1-Plasma- und Gewebekonzentrationen bestimmt. Die Messung der ET-Rezeptordichte und der Rezeptoraffinität erfolgte in Scatchard-Rezeptor-Bindungsstudien. Die Hälfte einer Gruppe von 44 hepatomtagenden Buffaloratten wurde über 28 Tage mit dem kombinierten ETA/B-Rezeptorantagonisten LU 302872 behandelt (orale Applikation). DIE ERGEBNISSE zeigen eine endogene irET-1-Produktion der MH-7777-Zellen. Exogene ET-1-Stimulation der Zellen bewirkt eine signifikante Proliferationssteigerung. Die Proliferationshemmung durch die beiden ETA-Rezeptorantagonisten ist schwächer ausgeprägt als die in zwei verschiedenen Proliferationsassays bestätigte Hemmung (p / The peptide endothelin-1 (ET-1) has growth-promoting properties besides its vasopressor characteristic. In order to gain information about its importance for tumor growth the ET system of the experimental liver tumor Morris hepatoma (MH)-7777 was characterized in vitro and in vivo. For the first time it was then tried to inhibit tumor growth in vivo by treatment with an ET receptor antagonist. METHODS: The endogenously produced immunoreactive (ir) ET-1 was quantified in the supernatant of MH-7777 cells. Cell growth at incubation with different concentrations of ET-1 and the ET receptor antagonists BQ 123, LU 135252 and LU 302872 was evaluated performing cell proliferation assays. In order to characterize the ET system in MH-7777 in vivo ir(big-)ET-1 concentrations were determined in plasma and tissue. ET receptor density and affinity in hepatoma was determined performing Scatchard receptor binding assays. Half of 44 hepatoma-bearing Buffalo rats received the combined ETA/B receptor antagonist LU 302872 for 28 days orally. THE RESULTS show an endogenous irET-1 production by MH-7777 cells. Exogenous ET-1 stimulation causes a significant increase in cell proliferation. Growth inhibitory action of ETA-receptor antagonists is not as strong as the inhibition (p