1,006 research outputs found
Elucidation of the activity, pharmacokinetics, and toxicity profiles of fasciocidal drug candidates 1,2,4-trioxolane OZ78 and 1,2,4,5-tetraoxane MT04
No full textAbstract: Fascioliasis is a disease belonging to the most neglected tropical diseases. Causative agents are the food borne trematodes Fasciola hepatica and Fasciola gigantica, whereas F. hepatica is especially of human concern. F. hepatica and F. gigantica are setteled in the liver, bile ducts, and gallbladder and are therefore termed as liver flukes.
About 2.4 to 17 million people are infected worldwide with F. hepatica leading to a global burden of about 35’206 disability-adjusted life years (DALYs). Fascioliasis is a disease not only of human concern, but affects also farm animals, especially sheep and cattle.
Triclabendazole is the only known drug active against juvenile and adult F. hepatica infection. There are no alternative drugs available characterized by a similar activity and safety profile as triclabendazole. Resistance against triclabendazole has already been described in sheep and is spreading over the world. However, to date no resistance in humans has been detected. Nonetheless, screening for new drugs is urgent.
OZ78 was originally synthesized for malaria drug discovery and is a peroxidic compound. This synthetic peroxide has shown promising in vitro and in vivo activity against juvenile and adult F. hepatica. Moreover, OZ78 has shown to be active against a triclabendazole resistant F. hepatica strain (Oberon isolate).
In the framework of this PhD thesis preclinical investigations were carried out to further strengthen our knowledge on the potential of the synthetic compounds OZ78 and the related derivative MT04 for the treatment of F. hepatica infection. The aim was to find a lead candidate for further studies and to get a better understanding of the drug properties (pharmacokinetic / pharmacodynamic) of these substances.
Different promising trioxanes and tetraoxanes were tested in vitro and in vivo in more detail with regard to F. hepatica activity and results compared to OZ78 (1,2,4-trioxolane). MT04 (1,2,4,5-tetraoxane) was found to be even more active in vitro and in vivo (in rats) against adult and juvenile F. hepatica infection than OZ78. In contrast to OZ78, MT04 has two peroxide bridges. A dose of 50 mg/kg was enough to reach a complete worm burden reduction of 100% against adult F. hepatica in rats, and for juvenile treatment, a dose of 100 mg/kg was required.
In parallel, OZ78 has been tested in sheep according to activity, tolerability, and pharmacokinetic profiles. OZ78 failed to cure fascioliasis in sheep after an application of 50 mg/kg orally or subcutaneously - no reduction in faecal egg count or worm burden could be measured.
To elucidate pharmacokinetic parameters of OZ78 in sheep plasma, a liquid chromatography mass spectrometry (LC/MS) method was developed and validated in terms of accuracy, precision, stability, and selectivity. OZ78 and OZ352 (Internal standard, I.S.) had to be detected in negative mode, according to the mass of deprotonated parent compounds. Protein precipitation was used for sample clean up, recoveries of three concentrations of OZ78 (5, 1.25, and 0.3125 µg/ml) and I.S. (2 µg/ml) were 84.4%, 69.6%, 78.6% and 85.8%, respectively. Calibration line ranged from 5 µg/ml to 0.15625 µg/ml. The developed method demonstrated to be accurate, precise, and selective.
The pharmacokinetic profile of OZ78 following oral application was characterised by a maximal plasma concentration (Cmax) of 45.8±13 µg/ml after 1 h (Tmax). An estimated elimination half-life (t1/2) of 1.0±0.1 h and a mean area under the plasma time curve (AUC) of 116.2±47 µg h/ml were calculated for the oral administration. On the other hand, following subcutaneous treatment with OZ78, Cmax and Tmax were 13.7±6.1 µg/ml and 0.9±0.4 h, respectively. The α and β half-lives were 4.5±4.3 h and 56.5±36 h, respectively and the mean AUC was 219.1±74 µg h/ml.
Further studies were needed to determine the difference in therapeutic outcomes between rats and sheep. The LC/MS method for OZ78 in sheep plasma was adapted and validated for rat plasma measurements. In addition the OZ78 LC/MS method could be approximated, validated, and used for MT04 measurement in sheep and in rat plasma.
OZ78 and MT04 were applied at a dose of 50 mg/kg to rats, and after different time-points, samples were collected. Studies with MT04 according to efficacy and pharmacokinetics in sheep are outstanding, but are planned.
Following oral administration of 50 mg/kg in rats, the Cmax of MT04 and OZ78 were 49.8±9.1 and 70.1±19.1 µg/ml after 2.7±1.2 h and 1.6±1.6 h (Tmax), respectively. The AUCs were estimated at 31’258.8±6’232.7 and 29’794.1±3’990.6 µg min/ml for MT04 and OZ78, respectively. Mean elimination half-lives (t1/2) of MT04 and OZ78 were 6.4±5.7 h and 2.5±1.5 h, respectively.
Toxicity of OZ78 and MT04 was determined on a liver cell line (HepG2). Different viability and toxicity assays were done with OZ78 or MT04 combined with different iron containing solutions (haemin, Fe(II), and Fe(III)) to get a better understanding of the toxicity profiles of these substances. Reactive oxygen species (ROS) production of MT04 and OZ78 was measured in combination with these iron-solutions. OZ78 was only moderately toxic combined with iron, whereas the combination of MT04 with iron resulted in a significant toxicity. Additionally, a high ROS signal could be measured especially in combination with haemin for both substances.
In summary, OZ78 and MT04 are promising lead candidates for the development of anti-Fasciola drugs. OZ78 and MT04 were active against juvenile and adult infection in rats. The therapy failure in sheep after oral treatment can be explained by a too short exposure of the flukes to the drug. Another application has to be tested in sheep. To date, it is not clear if the applied doses are toxic and, more studies especially in animals are needed. However, ROS formation seems to be responsible for activity of these substances. ---------- Zusammenfassung: Fasziolose ist eine Erkrankung, die zu den vernachlässigten Tropenkrankheiten zählt. Verursacher sind die durch Ernährung übertragbaren Trematoden Fasciola hepatica und Fasciola gigantica, wobei F. hepatica besonders für Menschen Besorgnis erregend ist.
F. hepatica und F. gigantica leben in der Leber, Gallengängen und Gallenblase, und werden deshalb auch als Leberegel bezeichnet.
Etwa 2.4 bis 17 Millionen Menschen sind weltweit mit F. hepatica infiziert, was zu einer weltweiten Bürde von etwa 35'206 behinderungsbedingten Lebensjahren führt. Fasziolose ist nicht nur eine Erkrankung von Menschen, sondern auch landwirtschaftliche Nutztiere wie Schafe und Rinder sind betroffen.
Triclabendazol ist die einzige Substanz, die gegen juvenile und adulte F. hepatica Infektion wirkt. Es gibt keine alternativen Medikamente mit gleicher Aktivität und gleichem Sicherheitsprofil wie Triclabendazol. Resistenzen gegen Triclabendazol sind bereits in Schafen vorhanden und verbreiten sich über die Welt. Bis jetzt sind aber noch keine Resistenzen im Menschen beschriebe worden. Trotzdem ist es wichtig nach neuen Medikamenten zu suchen.
OZ78 wurde ursprünglich für die Malariabehandlung synthetisiert und gehört zu den Peroxiden. Dieses synthetische Peroxid hat versprechende Aktivitäten in vitro und in vivo gegen juvenile und adulte F. hepatica gezeigt. Überdies war OZ78 auch gegen einen Triclabendazol resistenten Stamm (Oberon Isolat) aktiv.
Im Rahmen meiner Dissertation, wurden präklinische Untersuchungen durchgeführt um das Wissen über die versprechenden Substanzen OZ78 und MT04 in der Behandlung von F. hepatica Infektion zu erweitern. Das Ziel war eine neue Leitsubstanz für weitere Studien zu finden und die Wirkweise der Substanzen besser zu verstehen (Pharmakokinetik / Pharmakodynamik).
In einer in vitro und in vivo Studie wurden verschiedene Trioxane und Tetraoxane auf ihre F. hepatica Aktivität im Detail getestet und mit OZ78 (1,2,4-Trioxolan) verglichen. Aus dieser Studie kam hervor, dass MT04 (1,2,4,5-Tetraoxan) noch aktiver in vitro und in vivo (in Ratten) gegen adulte und juvenile F. hepatica Infektionen war als OZ78. Im Unterschied zu OZ78, hat MT04 zwei Peroxid-Brücken. Eine Dosis von 50 mg/kg genügte um eine komplette Reduktion der Wurmbelastung von 100% gegen adulte F. hepatica in Ratten zu erreichen, für eine juvenile Behandlung war eine Dosis von 100 mg/kg nötig.
Parallel wurde OZ78 im Schaf getestet und Aktivität, Toleranz und Pharmakokinetik untersucht. Aber OZ78 schaffte es nicht Fasziolose im Schaf nach einer Anwendung von 50 mg/kg OZ78 oral oder subkutan zu heilen, keine Reduktion von Stuhleiern oder Würmern konnte gemessen werden.
Um die pharmakokinetischen Parameter von OZ78 im Plasma zu bestimmen, musste eine Flüssigchromatographische Massenspektrometrische (LC/MS) Methode entwickelt und auf Genauigkeit, Präzision, Stabilität, und Selektivität validiert werden. OZ78 und OZ352 (interner Standard, I.S.) musste im Negativ-Modus nach der Masse der deprotonierten Muttersubstanz detektiert werden. Eine Proteinfällung wurde zur Probenvorbereitung angewendet. Die Wiederfindungen von OZ78 (5, 1.25, und 0.3125 µg/ml) und von I.S. (2 µg/ml) waren 84.4%, 69.6%, 78.6%, und 85.8%. Kalibrationskurve reichte von 5 µg/ml zu 0.15625 µg/ml. Die entwickelte Methode war genau, präzis, und selektiv.
Das Pharmakokinetik-Profil von OZ78 nach oraler Injektion zeigte eine maximale Plasma Konzentration von (Cmax) 45.8±13 µg/ml nach 1 h (Tmax) auf. Die Halbwertszeit (t1/2) betrug 1.0±0.1 h und eine mittlere Fläche unter der Plasma Zeit Kurve (AUC) von 116.2±47 µg h/ml wurde für die orale Anwendung berechnet. Auf der anderen Seite, nach subkutaner Injektion mit OZ78, wurden ein Cmax und ein Tmax von 13.7±6.1 µg/ml und 0.9±0.4 h berechnet. Die α und β Halbwertszeit waren 4.5±4.3 h und 56.5±36 h, und die mittlere AUC war 219.1±74 µg h/ml.
Weitere Studien waren nötig um den Unterschied im Behandlungsergebnis zwischen Ratte und Schaf zu erklären. Die LC/MS Methode von OZ78 für Schafplasma wurde für Rattenplasma angepasst und validiert. Zusätzlich konnte die OZ78 LC/MS Methode modifiziert, validiert und für MT04 Messung in Schaf und Ratten Plasma verwendet werden.
OZ78 und MT04 wurden in einer Dosis von 50 mg/kg Ratten verabreicht und nach verschiedenen Zeitpunkten wurden Samples gezogen. Studien mit MT04 betreffend Aktivität und Pharmakokinetik im Schaf sind noch ausstehend, sind aber in Planung.
Nach oraler Applikation von 50 mg/kg in Ratten, wurden Cmax Werte von MT04 und OZ78 49.8±9.1 und 70.1±19.1 µg/ml nach 2.7 h±1.2 und 1.6±1.6 h (Tmax) gemessen. Die berechnete AUC ergab 31’258.8±6’232.7 und 29’794.1±3’990.6 µg min/ml für MT04 und OZ78. Mittlere Halbwertszeiten (t1/2) für MT04 und OZ78 waren 6.4 ±5.7 h und 2.5±1.5 h.
Zuletzt wurde die Toxizität von OZ78 und MT04 mit einer Leberzelllinie (HegG2) bestimmt. Verschiedene Toxizitäts- und Viabilitäts Assays wurden mit OZ78 oder MT04 kombiniert mit verschiedenen Einsenlösungen (Hämin, Fe(II) und Fe(III)) angewandt um das Toxizitätsprofil besser zu verstehen. Reaktive Sauerstoffspezies (ROS) Produktion von MT04 und OZ78 wurden in Kombination mit diesen Eisenlösungen gemessen. OZ78 war nur mässig toxisch kombiniert mit Eisen, wobei eine signifikante Toxizität für MT04 in Kombination mit Eisen gefunden werden konnte. Ein hohes ROS Signal wurde für beide Substanzen vor allem in Kombination mit Haemin gemessen.
Zusammengefasst, OZ78 und MT04 sind vielversprechende „Lead“-Kandidaten in der Entwicklung eines Medikaments gegen Fasziola Infektionen. OZ78 und MT04 waren aktiv gegen juvenile und adulte Infektion in der Ratte. Das Therapieversagen in Schafen kann durch eine zu geringe Exposition der Saugwürmer im Schaf mit der Substanz erklärt werden. Eine andere Applikation im Schaf ist noch ausstehend. Bis jetzt lässt sich nicht sagen, wie toxisch die verwendeten Dosen sind, mehr Studien im Tier werden dafür benötigt. Die Aktivität der Substanzen scheint von der ROS Produktion abhängig zu sein
Repurposing of anticancer drugs: in vitro and in vivo activities against Schistosoma mansoni
No full textBACKGROUND: Drug discovery for the neglected tropical disease schistosomiasis has a high priority. Anticancer drugs, especially protein kinase inhibitors, might serve as a starting point for drug discovery owing to the importance of protein kinases in helminth growth and development. Furthermore, the Schistosoma mansoni genome encodes several genes for targets of drugs marketed for human use, including several anticancer drugs.
METHODS: In this study, we screened the approved oncology drug set of the National Cancer Institute's Developmental Therapeutic Program for antischistosomal activity. Drugs were tested in vitro against the larval and adult stage of S. mansoni. IC50 values and albumin binding were determined for active compounds. Lead compounds were tested in the chronic S. mansoni mouse model.
RESULTS: Eleven of the 114 compounds tested revealed IC50 values ≤ 10 μM against both S. mansoni stages. Five of these lost activity against adult S. mansoni in the presence of serum albumin. Of 6 compounds studied in vivo, the highest activity was observed from two kinase inhibitors trametinib, and vandetanib, which reduced worm burden by 63.6 and 48.1% respectively, after a single oral dose of 400 mg/kg body weight.
CONCLUSION: Our study has confirmed that oncology drugs possess antischistosomal activity. There is space for further investigation, including elucidation of the mechanisms of action of schistosome-active cancer drugs, application of different treatment courses, and structure-activity relationship studies for improving drug potency
Thrips Control/Variety Test in Cotton with Temik, Keiser, Ar, 1993
No full textAbstract
Cotton was planted on 14 May at the University of Arkansas Northeast Research and Extension Center in Keiser, AR. Plots were treated with Terrachlor + Temik or Terrachlor + No Temik using Gandy boxes. Plots were 4, 38-inch rows, 50 ft long arranged in a RCB design with 4 replications. Ratings were made on 27 May & 3, 9, & 17 Jun. Visual ratings were made on a scale of 1—10 with 10 = severe damage.</jats:p
Efficacy and safety of artemether against a natural Fasciola hepatica infection in sheep
No full textTriclabendazole is the current drug of choice against Fasciola spp. infections in livestock, but resistance has become a major problem. In this study, we assessed the efficacy and safety of artemether, a derivative of artemisinin, in sheep with a low natural Fasciola hepatica infection. Artemether was administered orally or intramuscularly; sheep were monitored for 8 h posttreatment and then once daily for adverse events, and drug efficacy was estimated by fecal egg count reductions and worm burden reductions. Single 40- and 80-mg/kg oral doses of artemether showed no effect on F. hepatica egg and worm burden. Treatment with a single 160-mg/kg intramuscular dose of artemether significantly reduced the egg burden (64.9%) and worm burden (91.3%). At half this dose, a worm burden reduction of 65.3% was obtained, which was still statistically significant (P > 0.05). The lowest intramuscular dose of artemether investigated (40 mg/kg) yielded no effect on egg counts and worm burden. There were no adverse events due to artemether; however, two abortions were observed 7 days posttreatment. In conclusion, artemether shows interesting fasciocidal properties in sheep, but embryotoxicity is of concern. Further studies are warranted to assess the potential of additional artemisinin derivatives and other peroxidic compounds for the treatment of Fasciola spp. infections in different ruminants
In vitro and in vivo antischistosomal activity of ferroquine derivatives
No full textSchistosomiasis is a neglected tropical disease and drug-repurposing is a useful strategy to fill its exhausted drug development pipeline. The ferrocenyl analogue of chloroquine, ferroquine, is an antimalarial in late-stage drug development. The aim of the present work was to study the antischistosomal activity of ferroquine against Schistosoma mansoni adult worms and newly transformed schistosomula (NTS) in vitro and in vivo. Hydroxyl-ferroquine and ruthenoquine were included to study the potential role of reactive oxygen species in the antischistosomal activity. Chloroquine and mefloquine, the later described for its antischistosomal properties, served as comparators.; All metal complexes were shown to be moderately cytotoxic on human cervix HeLa cancer cells and human fetal lung fibroblasts MRC-5. 72 hours post-incubation NTS exposed to 33.3 µM ruthenoquine had died, while ferroquine and hydroxyl-ferroquine treated worms were strongly affected. No activity was observed treating NTS with chloroquine at 33.3 µM. Incubation of adult S. mansoni with 33.3 µM of the organometallic derivatives were highly affected in viability but were still alive 72 hours post-incubation. Mefloquine showed the highest activity against NTS and adult S. mansoni. Low total worm burden reductions of 0-36% were observed following oral administration of 200-800 mg/kg of the ferroquine derivatives to S. mansoni-infected mice.; The organometallic compounds evaluated in this study revealed moderate in vitro activity against both larval and adult stages of S. mansoni but low in vivo activity. No correlation can be drawn between the antimalarial and antischistosomal activity of chloroquine analogues and oxidative shock does not seem to play a role in the activity of these compounds against S. mansoni
Post 'Celtic Tiger' Ireland, Silver Vigilantes and Public Sociology: Protesting Against Global Neoliberalisation
No full textIt is not just publicly funded universities that are facing a cold and hard future in the aftershock of the 2008 global banking crisis. Nations, such as Ireland, are similarly affected as states seek to appease 'the markets' and cover private banks' losses at the public's expense. As this wave of neoliberalisation, or market fundamentalism, proceeds we may ask: what is the role of sociology? Drawing from an exploratory study of financial activism, notably silver vigilantism and the Crash JP Morgan Campaign, this paper endorses global public sociology among threatened publics. As per Michael Burawoy's calls for public sociology, this entails promoting reflexive knowledge and democratic dialogue in the defence of civil society. After outlining the core tenets, strengths and weaknesses of silver vigilantism, the role of public sociology and the need for further research are underscored as the economic crisis continues in post 'Celtic Tiger' Ireland and beyond.Public Sociology; Neoliberalisation; Money; Protest; the Internet
Development of an in vitro drug sensitivity assay for Trichuris muris first-stage larvae
No full textTrichuriasis represents a major public health problem in the developing world and is regarded as a neglected disease. Albendazole and mebendazole, the two drugs of choice against trichuriasis display only moderate cure rates, hence alternative drugs are needed. To identify candidate compounds, in vitro drug sensitivity testing currently relies on the adult Trichuris muris motility assay. The objective of the present study was to develop a simple and cost-effective drug sensitivity assay using Trichuris muris first-stage larvae (L1).; Several potential triggers that induce hatching of T. muris were studied, including gastrointestinal enzymes, acidic environment and intestinal microflora. Next, optimal culture conditions for T. muris L1 were determined assessing a wide range of culture media. T. muris L1 were incubated in the presence of mebendazole, ivermectin, nitazoxanide, levamisole or oxantel pamoate at 37°C. The viability of the parasites was evaluated microscopically after 24 hours. The usefulness of fluorescent markers (resazurin, calcein AM, ethidium homodimer-1 or fluorescein-conjugated albumin) in drug sensitivity testing was also assessed.; The established L1 motility assay provided accurate and reproducible drug effect data in vitro. IC50 values for oxantel pamoate, levamisole and nitazoxanide were 0.05, 1.75 and 4.43 μg/mL, respectively. Mebendazole and ivermectin failed to show any trichuricidal effect on L1. No correlation was found between data from the four fluorescent markers and the comparative motility assay.; The motility assay based on L1 was found suitable for drug sensitivity screening. It is rather simple, cost-effective, time-saving and sustains medium-throughput testing. Furthermore, it greatly reduces the need for the animal host and is therefore more ethical. None of the viability markers assessed in this study were found to be satisfactory
Lung cancer in the Swiss HIV Cohort Study: role of smoking, immunodeficiency and pulmonary infection
No full textBACKGROUND: Immunodeficiency and AIDS-related pulmonary infections have been suggested as independent causes of lung cancer among HIV-infected persons, in addition to smoking. METHODS: A total of 68 lung cancers were identified in the Swiss HIV Cohort Study (SHCS) or through linkage with Swiss Cancer Registries (1985-2010), and were individually matched to 337 controls by centre, gender, HIV-transmission category, age and calendar period. Odds ratios (ORs) were estimated by conditional logistic regression. RESULTS: Overall, 96.2% of lung cancers and 72.9% of controls were ever smokers, confirming the high prevalence of smoking and its strong association with lung cancer (OR for current vs never=14.4, 95% confidence interval (95% CI): 3.36-62.1). No significant associations were observed between CD4+ cell count and lung cancer, neither when measured within 1 year (OR for <200 vs ≥500=1.21, 95% CI: 0.49-2.96) nor further back in time, before lung cancer diagnosis. Combined antiretroviral therapy was not significantly associated with lung cancer (OR for ever vs never=0.67, 95% CI: 0.29-1.52), and nor was a history of AIDS with (OR=0.49, 95% CI: 0.19-1.28) or without (OR=0.53, 95% CI: 0.24-1.18) pulmonary involvement. CONCLUSION: Lung cancer in the SHCS does not seem to be clearly associated with immunodeficiency or AIDS-related pulmonary disease, but seems to be attributable to heavy smoking
A Decade of HAART: The Development and Global Impact of Highly Active Antiretroviral Therapy. Edited by José M. Zuninga, Alan Whiteside, Amin Ghaziani, and John G. Bartlett. New York: Oxford University Press, 2008.
No full textOutcomes of antiretroviral therapy in the Swiss HIV Cohort Study: Latent class analysis
No full textAn in-depth understanding of the different groups that make up the HIV-infected population should inform prevention and care. Using latent class analysis (LCA) we identified seven groups with similar socio-demographic and behavioral characteristics at enrolment in the Swiss HIV Cohort Study: older gay men, younger gay men, older heterosexual men, injection drug users, single migrants, migrant women in partnerships and heterosexual men and women. Outcomes of combination antiretroviral therapy (ART) were analyzed in 1,633 patients starting ART. Compared to older gay men, the probability of a virologic response to ART was reduced in single migrants, in older heterosexual men and in IDUs. Loss to follow-up was higher in single migrants and IDUs, and mortality was increased in older heterosexual men and IDUs. Socio-behavioral groups identified by LCA allow insights above what can be gleaned from traditional transmission groups, and may identify patients who could benefit from targeted interventions
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