Biomedical subjects

Hartmut Zehender

Publications and source records attributed to Hartmut Zehender.

3 recordsLinked to original sources

PubMed2005

A chemoinformatics analysis of hit lists obtained from high-throughput affinity-selection screening.

The high-throughput affinity-selection screening platform SpeedScreen was recently reported by the Novartis Institutes for BioMedical Research as a homogeneous, label-free screening technology with mass-spectrometry readout. SpeedScreen relies on the screening of compound mixtures with various target proteins and uses fast size-exclusion chromatography to separate target-bound from unbound substances. After disintegration of the target-binder complex, the binder molecules are identified by their molecular masses using liquid chromatography/mass spectrometry. The authors report an analysis of the molecular properties of hits obtained with SpeedScreen on 26 targets screened within the past few years at Novartis using this technology. Affinity-based SpeedScreen is a robust high-throughput screening technology that does not accumulate frequent hitters or potential covalent binders. The hits are representative of the most commonly identified scaffold classes observed for known drugs. Validated SpeedScreen hits tend to be enriched on more lipophilic and larger-molecular-weight compounds compared to the whole library. The potential for a reduced SpeedScreen screening set to be used in case only limited protein quantities are available is evaluated. Such a reduced compound set should also maximize the coverage of the high-performing regions of the chemical property and class spaces; chemoinformatics methods including genetic algorithms and divisive K-means clustering are used for this aim.

Chromatography, High Pressure Liquid↗

PubMed2004

A locally active antiinflammatory macrolide (MLD987) for inhalation therapy of asthma.

One of the characteristic features of asthma is a persistent pulmonary inflammation, with increased numbers of eosinophils and activated T-lymphocytes in the airways. T-helper cells of the Th2 phenotype play a pivotal role in the pathogenesis of asthma, and they are believed to orchestrate the asthmatic response by releasing a wide repertoire of cytokines. Herein, we describe the design, synthesis, and evaluation in models of allergic asthma of a locally active T-cell modulator, MLD987 (1). Compound 1 is a potent immunosuppressant that inhibits the activation, proliferation, and release of cytokines from T-cells with IC(50) values in the low nanomolar range. In a Brown-Norway rat model of allergic asthma, 1, when given into the airways by intratracheal administration (ED(50) = 1 mg/kg) or by inhalation (ED(50) = 0.4 mg/kg), potently reduced the influx of leukocytes into bronchoalveolar lavage fluid samples obtained from antigen-challenged animals. In contrast, 1 had an appreciably weaker activity in this model when given orally or intravenously. Pharmacokinetic evaluation in rat and rhesus monkey showed that 1 had both a low oral (2-4%) and a low pulmonary (7%, monkey) bioavailability. These findings are consistent with a local site of action of the compound and rule out that its antiinflammatory activity in the lung was caused by systemically absorbed material, which had been swallowed during inhalation or which had entered the circulation via the airways. Local administration and the metabolically soft structure of 1, which favors rapid systemic metabolism to less immunosuppressive metabolite 2, are the main reasons for the low exposure and weak systemic activity of the compound. Administration of a locally active compound such as 1, by inhalation, should reduce systemic side effects. Our results indicate that 1 has the potential to serve as an alternative to inhaled glucocorticosteroids for the long-term therapy of asthma of all grades of severity.

Administration, Inhalation↗

PubMed2004

SpeedScreen: The "missing link" between genomics and lead discovery.

SpeedScreen is a novel, label-free, in-solution, affinity-based selection methodology for high-throughput screening (HTS) developed at Novartis Pharma. The SpeedScreen protocol comprises in-solution affinity selection, followed by size exclusion chromatography in combination with microbore-liquid-chromatography/electrospray-ionization mass spectrometry (micro-LC/ESI-MS). The authors describe the basic concept behind assay development, HTS, and data analysis with the SpeedScreen technology. Advantages and limitations of SpeedScreen compared to alternative screening technologies are discussed, and an example is given from a SpeedScreen campaign applying this innovative affinity selection concept in HTS.

Chromatography, Gel↗