Epothilones as lead structures for the synthesis-based discovery of new chemotypes for microtubule stabilization

Epothilones are macrocyclic bacterial natural products with potent microtubule-stabilizing and antiproliferative activity. They have served as successful lead structures for the development of several clinical candidates for anticancer therapy. However, the structural diversity of this group of clinical compounds is rather limited, as their structures show little divergence from the original natural product leads. Our own research has explored the question of whether epothilones can serve as a basis for the development of new structural scaffolds, or chemotypes, for microtubule stabilization that might serve as a basis for the discovery of new generations of anticancer drugs. We have elaborated a series of epothilone-derived macrolactones whose overall structural features significantly deviate from those of the natural epothilone scaffold and thus define new structural families of microtubule-stabilizing agents. Key elements of our hypermodification strategy are the change of the natural epoxide geometry from cis to trans, the incorporation of a conformationally constrained side chain, the removal of the C3-hydroxyl group, and the replacement of C12 with nitrogen. So far, this approach has yielded analogs 30 and 40 that are the most advanced, the most rigorously modified, structures, both of which are potent antiproliferative agents with low nanomolar activity against several human cancer cell lines in vitro. The synthesis was achieved through a macrolactone-based strategy or a high-yielding RCM reaction. The 12-aza-epothilone ("azathilone" 40) may be considered a "non-natural" natural product that still retains most of the overall structural characteristics of a true natural product but is structurally unique, because it lies outside of the general scope of Nature's biosynthetic machinery for polyketide synthesis. Like natural epothilones, both 30 and 40 promote tubulin polymerization in vitro and at the cellular level induce cell cycle arrest in mitosis. These facts indicate that cancer cell growth inhibition by these compounds is based on the same mechanistic underpinnings as those for natural epothilones. Interestingly, the 9,10-dehydro analog of 40 is significantly less active than the saturated parent compound, which is contrary to observations for natural epothilones B or D. This may point to differences in the bioactive conformations of N-acyl-12-aza-epothilones like 40 and natural epothilones. In light of their distinct structural features, combined with an epothilone-like (and taxol-like) in vitro biological profile, 30 and 40 can be considered as representative examples of new chemotypes for microtubule stabilization. As such, they may offer the same potential for pharmacological differentiation from the original epothilone leads as various newly discovered microtubule-stabilizing natural products with macrolactone structures, such as laulimalide, peloruside, or dictyostatin.

Natural products as leads for anticancer drug discovery: discovery of new chemotypes of microtubule stabilizers through reengineering of the epothilone scaffold

Epothilones are bacterial macrolides with potent microtubule-stabilizing and antiproliferative activity, which have served as successful lead structures for the discovery of several clinical candidates for cancer treatment. Overall, seven epothilone-type agents have been advanced to clinical evaluation in humans so far and one of these has been approved by the FDA in 2007 for clinical use in breast cancer patients. Notwithstanding these impressive numbers, however, the structural diversity represented by the collection of epothilone analogs that have been (or still are) investigated clinically is rather limited and their individual structures show little divergence from the original natural product leads. In contrast, we have elaborated a series of epothilone-derived macro-lactones, whose overall structural features significantly deviate from those of the natural epothilone scaffold and thus define new structural families of microtubule-stabilizing agents. Key elements of our hypermodification strategy are the change of the natural epoxide geometry from cis to trans, the incorporation of conformationally constrained side chains, the removal of the C(3)-hydroxyl group, and the replacement of C(12) with nitrogen. The latter modification leads to aza-macrolides that may be described as 'non-natural natural products'.

Development of PCR/dot blot assay for specific detection and differentiation of taeniid cestode eggs in canids

We report the development of a colourimetric PCR/dot blot assay targeting the mitochondrial gene NADH dehydrogenase subunit 1 (nad1) for differential diagnosis of taeniid eggs. Partial sequences of the cestode nad1 gene were aligned and new primers were designed based on conserved regions. Species-specific oligonucleotide probes (S-SONP) for canine taeniid cestodes were then designed manually based on the variable region between the conserved primers. Specifically, S-SONP were designed for the Taenia crassiceps, T. hydatigena, T. multiceps, T. ovis, T. taeniaeformis, Echinococcus granulosus (genotype 1), E. multilocularis and E. vogeli. Each probe showed high specificity as no cross-hybridisation with any amplified nad1 fragment was observed. We evaluated the assay using 49 taeniid egg-positive samples collected from dogs in Zambia. DNA from 5 to 10 eggs was extracted in each sample. Using the PCR/dot blot assay, the probes successfully detected PCR products from T. hydatigena in 42 samples, T. multiceps in 3 samples, and both species (mixed infection) in the remaining 4 samples. The results indicate that the PCR/dot blot assay is a reliable alternative for differential diagnosis of taeniid eggs in faecal samples.

[Complement--a phylogenetically old system as a new player in the development of atherosclerosis]

Atherosclerotic diseases such as coronary artery disease and ischaemic stroke are caused by chronic inflammation in arterial vessel walls. The complement system is part of the innate immune system. It is involved in many processes contributing to onset and development of atherosclerotic plaques up to the final stage of acute thrombotic events. This is due to its prominent role in inflammatory processes. In addition, there is increasing evidence that interactions between complement and coagulation provide a link between inflammation and thrombosis. On the other hand, the complement system also has an atheroprotective function through the clearance of apoptotic material. The knowledge of these complex mechanisms will become increasingly important, also for clinicians, since it may lead to novel therapeutic and diagnostic options. Therapies targeting the complement system have the potential to reduce tissue damage caused by acute ischaemic events. Whether early anti-inflammatory and anti-complement therapy may be able to prevent atherosclerosis, remains a hot topic for research.

Anticancer drugs from nature--natural products as a unique source of new microtubule-stabilizing agents

This review article provides an overview on the current state of research in the area of microtubule-stabilizing agents from natural sources, with a primary focus on the biochemistry, biology, and pharmacology associated with these compounds. A variety of natural products have been discovered over the last decade to inhibit human cancer cell proliferation through a taxol-like mechanism. These compounds represent a whole new range of structurally diverse lead structures for anticancer drug discovery.

The HeartQoL: Part I. Development of a new core health-related quality of life questionnaire for patients with ischemic heart disease

Background: Evaluation of health-related quality of life (HRQL) is important in improving the quality of patient care. Methods: The HeartQoL Project, with cross-sectional and longitudinal phases, was designed to develop a core ischemic heart disease (IHD) specific HRQL questionnaire, to be called the HeartQoL, for patients with angina, myocardial infarction (MI), or ischemic heart failure. Patients completed a battery of questionnaires and Mokken scaling analysis was used to identify items in the HeartQoL questionnaire. Results: We enrolled 6384 patients (angina, n = 2111, 33.1%; MI, n = 2351, 36.8%; heart failure, n = 1922, 30.1%) across 22 countries and 15 languages. The HeartQoL questionnaire comprises 14-items with 10-item physical and 4-item emotional subscales which are scored from 0 (poor HRQL) to 3 (better HRQL) with a global score if needed. The mean baseline HeartQoL global score was 2.2 (±0.5) in the total group and was different (p < 0.001) by diagnosis (MI, 2.4 ± 0.5; angina, 2.2 ± 0.6; and heart failure, 2.1 ± 0.6). Conclusion: The HeartQoL questionnaire, with global and subscale scores, has the potential to allow clinicians and researchers to (a) assess baseline HRQL, (b) make between-diagnosis comparisons of HRQL, and (c) evaluate change in HRQL in patients with angina, MI, or heart failure with a single IHD-specific HRQL instrument.

Rat lungs show a biphasic formation of new alveoli during postnatal development

Roughly 90% of the gas-exchange surface is formed by alveolarization of the lungs. To the best of our knowledge, the formation of new alveoli has been followed in rats only by means of morphological description or interpretation of semiquantitative data until now. Therefore, we estimated the number of alveoli in rat lungs between postnatal days 4 and 60 by unambiguously counting the alveolar openings. We observed a bulk formation of new alveoli between days 4 and 21 (17.4 times increase from 0.8 to 14.3 millions) and a second phase of continued alveolarization between days 21 and 60 (1.3 times increase to 19.3 million). The (number weighted) mean volume of the alveoli decreases during the phase of bulk alveolarization from ∼593,000 μm(3) at day 4 to ∼141,000 μm(3) at day 21, but increases again to ∼298,000 μm(3) at day 60. We conclude that the "bulk alveolarization" correlates with the mechanism of classical alveolarization (alveolarization before the microvascular maturation is completed) and that the "continued alveolarization" follows three proposed mechanisms of late alveolarization (alveolarization after microvascular maturation). The biphasic pattern is more evident for the increase in alveolar number than for the formation of new alveolar septa (estimated as the length of the free septal edge). Furthermore, a striking negative correlation between the estimated alveolar size and published data on retention of nanoparticles was detected.

The new bern PET cyclotron, its research beam line, and the development of an innovative beam monitor detector

The new Bern cyclotron laboratory aims at industrial radioisotope production for PET diagnostics and multidisciplinary research by means of a specifically conceived beam transfer line, terminated in a separate bunker. In this framework, an innovative beam monitor detector based on doped silica and optical fibres has been designed, constructed, and tested. Scintillation light produced by Ce and Sb doped silica fibres moving across the beam is measured, giving information on beam position, shape, and intensity. The doped fibres are coupled to commercial optical fibres, allowing the read-out of the signal far away from the radiation source. This general-purpose device can be easily adapted for any accelerator used in medical applications and is suitable either for low currents used in hadrontherapy or for currents up to a few μA for radioisotope production, as well as for both pulsed and continuous beams.

Development of a new real-time polymerase chain reaction assay to detect Duck adenovirus A DNA and application to samples from Swiss poultry flocks.

Between 2008 and 2012, commercial Swiss layer and layer breeder flocks experiencing problems in laying performance were sampled and tested for infection with Duck adenovirus A (DAdV-A; previously known as Egg drop syndrome 1976 virus). Organ samples from birds sent for necropsy as well as blood samples from living animals originating from the same flocks were analyzed. To detect virus-specific DNA, a newly developed quantitative real-time polymerase chain reaction method was applied, and the presence of antibodies against DAdV-A was tested using a commercially available enzyme-linked immunosorbent assay. In 5 out of 7 investigated flocks, viral DNA was detected in tissues. In addition, antibodies against DAdV-A were detected in all of the flocks.